U.S. patent application number 13/988476 was filed with the patent office on 2014-02-20 for light emitting device comprising a lightguide film and aligned coupling lightguides.
The applicant listed for this patent is Zane Coleman, Anthony John Nichol. Invention is credited to Zane Coleman, Anthony John Nichol.
Application Number | 20140049983 13/988476 |
Document ID | / |
Family ID | 46084436 |
Filed Date | 2014-02-20 |
United States Patent
Application |
20140049983 |
Kind Code |
A1 |
Nichol; Anthony John ; et
al. |
February 20, 2014 |
LIGHT EMITTING DEVICE COMPRISING A LIGHTGUIDE FILM AND ALIGNED
COUPLING LIGHTGUIDES
Abstract
A light emitting device includes a film-based lightguide and
coupling lightguides having ends stacked and aligned. In one
embodiment, the light emitting device comprises a relative position
maintaining element that extends beyond the light input surface
defined by the stacked ends of an array of coupling lightguides. In
another embodiment, a light emitting device comprises an alignment
guide or cavity.
Inventors: |
Nichol; Anthony John;
(Chicago, IL) ; Coleman; Zane; (Elmhurst,
IL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Nichol; Anthony John
Coleman; Zane |
Chicago
Elmhurst |
IL
IL |
US
US |
|
|
Family ID: |
46084436 |
Appl. No.: |
13/988476 |
Filed: |
November 18, 2011 |
PCT Filed: |
November 18, 2011 |
PCT NO: |
PCT/US11/61528 |
371 Date: |
August 9, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61415250 |
Nov 18, 2010 |
|
|
|
Current U.S.
Class: |
362/610 |
Current CPC
Class: |
G02B 6/0053 20130101;
G02B 27/0101 20130101; G02B 6/0036 20130101; G02B 27/0172 20130101;
G02B 6/0043 20130101; G02B 6/0028 20130101; G02B 6/0018 20130101;
G02B 6/0061 20130101 |
Class at
Publication: |
362/610 |
International
Class: |
F21V 8/00 20060101
F21V008/00 |
Claims
1. A light emitting device comprising: a light source having an
optical axis; a relative position maintaining element; and a
lightguide comprising a film having a thickness not greater than
0.5 millimeters, the lightguide having a lightguide region and an
array of coupling lightguides continuous with the lightguide
region, wherein each coupling lightguide of the array of coupling
lightguides terminates in an edge and at least one of the array of
coupling lightguides is folded at least partially around the
relative position maintaining element such that the edges of the
array of coupling lightguides form a stack defining a light input
surface, wherein light from the light source enters into the light
input surface and propagates by total internal reflection within
each coupling lightguide to the lightguide region and the relative
position maintaining element extends past the light input surface
in a direction parallel to the optical axis.
2. The light emitting device of claim 1 wherein the relative
position maintaining element extends past the light source in a
direction parallel to the optical axis.
3. The light emitting device of claim 1 wherein the relative
position maintaining element comprises an array of guide members
and the at least one of the array coupling lightguide is folded at
least partially around a guide member.
4. The light emitting device of claim 1 further comprising a light
redirecting optical element positioned to direct the light from the
light source to the light input surface.
5. The light emitting device of claim 4 wherein at least one of the
light source and the light redirecting optical element is coupled
to the relative position maintaining element.
6. A display comprising the light emitting device of claim 1 and a
spatial light modulator wherein the light emitting device
illuminates the spatial light modulator.
7. A light emitting device comprising: a light source; a lightguide
comprising a film having a thickness not greater than 0.5
millimeters, the lightguide having a lightguide region and an array
of coupling lightguides continuous with the lightguide region,
wherein each coupling lightguide of the array of coupling
lightguides terminates in an edge and at least one of the array of
coupling lightguides is folded such that the edges of the array of
coupling lightguides form a stack defining a light input surface;
and a light redirecting optical element positioned to direct light
from the light source to the light input surface such that the
light propagates by total internal reflection within each coupling
lightguide to the lightguide region, wherein the light redirecting
optical element comprises an alignment guide configured to align
the light redirecting optical element to the light input
surface.
8. The light emitting device of claim 7 wherein the alignment guide
aligns the light redirecting optical element to the light input
surface in a direction of the stack.
9. The light emitting device of claim 7 wherein the alignment guide
constrains the edges of the coupling lightguides in a direction of
the stack.
10. The light emitting device of claim 7 wherein the light
redirecting optical element is a secondary optic for the light
source.
11. The light emitting device of claim 10 wherein the light
redirecting optical element collimates the light from the light
source such that the light incident on the light input surface has
an angular full-width at half maximum intensity less than 60
degrees in a plane orthogonal to the light input surface.
12. The light emitting device of claim 7 further comprising a
relative position maintaining element comprising an array of guide
members and the at least one of the array of coupling lightguide is
folded at least partially around the array of guide members.
13. A display comprising the light emitting device of claim 7 and a
spatial light modulator wherein the light emitting device
illuminates the spatial light modulator.
14. A light emitting device comprising: a light source; a
lightguide formed from a film having a thickness not greater than
0.5 millimeters, the lightguide having a lightguide region and an
array of coupling lightguides continuous with the lightguide
region, wherein each coupling lightguide of the array of coupling
lightguides terminates in an edge and at least one of the array of
coupling lightguides is folded such that the edges of the array of
coupling lightguides form a stack defining a light input surface;
and an alignment guide defining a cavity, wherein the light input
surface is positioned within the cavity and light from the light
source propagates into the light input surface such that that the
light propagates by total internal reflection within each coupling
lightguide to the lightguide region.
15. The light emitting device of claim 14 wherein the alignment
guide redirects light from the light source such that the
redirected light is more collimated in a first plane orthogonal to
an optical axis of the light from the light source.
16. The light emitting device of claim 15 wherein the first plane
is parallel to direction of the stack.
17. The light emitting device of claim 14 wherein the light
incident on the light input surface has an angular full-width at
half maximum intensity less than 60 degrees in a plane orthogonal
to the light input surface.
18. A display comprising the light emitting device of claim 14 and
a spatial light modulator wherein the light emitting device
illuminates the spatial light modulator.
19. A method of manufacturing a light emitting device, said method
comprising: separating a plurality of regions in a film with a
thickness less than 0.5 millimeters to form a plurality of coupling
lightguides continuous with a lightguide region of the film;
folding at least one coupling lightguide of the plurality of
coupling lightguides such that ends of the plurality of coupling
lightguides form a stack defining a light input surface; and
positioning a light redirecting optical element to receive light
from a light source and transmit the light to the light input
surface such that the light propagates within each coupling
lightguide to the lightguide region, wherein the light redirecting
optical element comprises one of an alignment guide and a cavity
defined within the light redirecting optical element configured to
align the light input surface with the light redirecting optical
element.
20. The method of claim 19 wherein positioning a light redirecting
optical element comprises positioning the light input surface
within the cavity.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application claims the benefit of U.S. Provisional
Application No. 61/415,250, entitled "Light emitting device
comprising a lightguide film and light turning optical element,"
filed Nov. 18, 2010, the entire contents of which is incorporated
by reference herein.
TECHNICAL FIELD
[0002] The subject matter disclosed herein generally relates to
light emitting devices such as light fixtures, backlights,
frontlights, light emitting signs, passive displays, and active
displays and their components and method of manufacture.
BACKGROUND
[0003] Conventionally, in order to reduce the thickness of displays
and backlights, edge-lit configurations using rigid lightguides
have been used to receive light from the edge of and direct light
out of a larger area face. These types of light emitting devices
are typically housed in relatively thick, rigid frames that do not
allow for component or device flexibility and require long lead
times for design changes. The volume of these devices remains large
and often includes thick or large frames or bezels around the
device. The thick lightguides (typically 2 millimeters (mm) and
larger) limit the design configurations, production methods, and
illumination modes.
[0004] The ability to further reduce the thickness and overall
volume of these area light emitting devices has been limited by the
ability to couple sufficient light flux into a thinner lightguide.
Typical LED light sources have a light emitting area dimension of
at least 1 mm, and there is often difficulty controlling the light
entering, propagating through, and coupled out of the 2 mm
lightguide to meet design requirements. The displays incorporating
the 2 mm lightguides are typically limited to small displays having
a diagonal dimension of 33 centimeters (cm) or less. Many system
sizes are thick due to designs that use large light sources and
large input coupling optics or methods. Some systems using one
lightguide per pixel (such as fiber optic based systems) require a
large volume and have low alignment tolerances. In production, thin
lightguides have been limited to coatings on rigid wafers for
integrated optical components.
SUMMARY
[0005] In one embodiment, a light emitting device comprises a light
source having an optical axis; a relative position maintaining
element; and a lightguide comprising a film having a thickness not
greater than 0.5 millimeters. The lightguide includes a lightguide
region and an array of coupling lightguides continuous with the
lightguide region. Each coupling lightguide of the array of
coupling lightguides terminates in an edge and at least one of the
array of coupling lightguides is folded at least partially around
the relative position maintaining element such that the edges of
the array of coupling lightguides form a stack defining a light
input surface. Light from the light source enters into the light
input surface and propagates by total internal reflection within
each coupling lightguide to the lightguide region. The relative
position maintaining element extends past the light input surface
in a direction parallel to the optical axis.
[0006] In another embodiment, a light emitting device comprises a
light source and a lightguide comprising a film having a thickness
not greater than 0.5 millimeters. The lightguide includes a
lightguide region and an array of coupling lightguides continuous
with the lightguide region. Each coupling lightguide of the array
of coupling lightguides terminates in an edge and at least one of
the array of coupling lightguides is folded such that the edges of
the array of coupling lightguides form a stack defining a light
input surface. The light emitting device also comprises a light
redirecting optical element positioned to direct light from the
light source to the light input surface such that the light
propagates by total internal reflection within each coupling
lightguide to the lightguide region. The light redirecting optical
element comprises an alignment guide configured to align the light
redirecting optical element to the light input surface.
[0007] In another embodiment, a light emitting device comprises a
light source and a lightguide formed from a film having a thickness
not greater than 0.5 millimeters. The lightguide includes a
lightguide region and an array of coupling lightguides continuous
with the lightguide region. Each coupling lightguide of the array
of coupling lightguides terminates in an edge and at least one of
the array of coupling lightguides is folded such that the edges of
the array of coupling lightguides form a stack defining a light
input surface. The light emitting device also comprises an
alignment guide defining a cavity, wherein light input surface is
positioned within the cavity and light from the light source
propagates into the light input surface such that that the light
propagates by total internal reflection within each coupling
lightguide to the lightguide region.
[0008] In another embodiment, a method of manufacturing a light
emitting device comprises separating a plurality of regions in a
film with a thickness less than 0.5 millimeters to form a plurality
of coupling lightguides continuous with a lightguide region of the
film, folding at least one coupling lightguide of the plurality of
coupling lightguides such that ends of the plurality of coupling
lightguides form a stack defining a light input surface, and
positioning a light redirecting optical element to receive light
from a light source and transmit the light to the light input
surface such that the light propagates within each coupling
lightguide to the lightguide region, wherein the light redirecting
optical element comprises one of an alignment guide and a cavity
defined within the light redirecting optical element configured to
align the light input surface with the light redirecting optical
element.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] FIG. 1 is a top view of one embodiment of a light emitting
device comprising a light input coupler disposed on one side of a
lightguide.
[0010] FIG. 2 is a perspective view of one embodiment of a light
input coupler with coupling lightguides folded in the -y
direction.
[0011] FIG. 3 is a top view of one embodiment of a light emitting
device with three light input couplers on one side of a
lightguide.
[0012] FIG. 4 is a top view of one embodiment of a light emitting
device with two light input couplers disposed on opposite sides of
a lightguide.
[0013] FIG. 5 is a top view of one embodiment of a light emitting
device with two light input couplers disposed on the same side of a
lightguide wherein the optical axes of the light sources are
oriented substantially toward each other.
[0014] FIG. 6 is a cross-sectional side view of one embodiment of a
light emitting device with a substantially flat light input surface
comprised of flat edges of a coupling lightguide disposed to
receive light from a light source.
[0015] FIG. 7 is a cross-sectional side view of one embodiment of a
light emitting device with a light input coupler with a light input
surface with refractive and flat surface features on the light
input surface wherein light totally internal reflects on some outer
surfaces similar to a hybrid refractive-TIR Fresnel lens.
[0016] FIG. 8 is a cross-sectional side view of one embodiment of a
light emitting device wherein the coupling lightguides and the
light input surface are optically coupled to the light source.
[0017] FIG. 9 is a cross-sectional side view of one embodiment of a
light emitting device wherein the coupling lightguides are held in
place by a sleeve and the edge surfaces are effectively planarized
by an optical adhesive or material such as a gel between the ends
of the coupling lightguides and the sleeve with a flat outer
surface adjacent the light source.
[0018] FIG. 10 is a top view of one embodiment of a backlight
emitting red, green, and blue light.
[0019] FIG. 11 is a cross-sectional side view of one embodiment of
a light emitting device comprising a light input coupler and
lightguide with a reflective optical element disposed adjacent a
surface.
[0020] FIG. 12 is a cross-sectional side view of a region of one
embodiment of a display illuminated by red, green, and blue
lightguides wherein the locations of the pixels of the display
correspond to light emitting regions of the lightguide separated by
color.
[0021] FIG. 13 is a cross-sectional side view of a region of one
embodiment of a color sequential display.
[0022] FIG. 14 is a cross-sectional side view of a region of one
embodiment of a spatial display (such as a liquid crystal
display).
[0023] FIG. 15 is a cross-sectional side view of a region of one
embodiment of a display comprising a white light source
backlight.
[0024] FIG. 16 is a cross-sectional side view of a region of one
embodiment of a display comprising a wavelength converting
backlight.
[0025] FIG. 17 is a cross-sectional side view of a region of one
embodiment of a display with a backlight comprising a plurality of
lightguides emitting different colored light in predetermined
spatial patterns.
[0026] FIG. 18 is a top view of one embodiment of a light emitting
device comprising two light input couplers with light sources on
the same edge in the middle region oriented in opposite
directions.
[0027] FIG. 19 is a top view of one embodiment of a light emitting
device comprising one light input coupler with coupling lightguides
folded toward the -y direction and then folded in the +z direction
toward a single light source.
[0028] FIG. 20 is a cross-sectional side view of one embodiment of
a display optically coupled to a film lightguide.
[0029] FIG. 21 is a cross-sectional side view of one embodiment of
a spatial display comprising a film-based lightguide frontlight
optically coupled to a reflective spatial light modulator.
[0030] FIG. 22 is a cross-sectional side view of one embodiment of
a spatial display comprising a front-lit film lightguide disposed
adjacent to a reflective spatial tight modulator.
[0031] FIG. 23 is a cross-sectional side view of one embodiment of
a spatial display comprising a front-lit film lightguide optically
coupled to a reflective spatial light modulator with light
extraction features on a side of the lightguide nearest the
reflective spatial light modulator.
[0032] FIG. 24 is a cross-sectional side view of one embodiment of
a spatial display comprising a front-lit film lightguide disposed
within a reflective spatial light modulator.
[0033] FIG. 25 is a cross-sectional side view of one embodiment of
a light emitting device comprising a light input coupler disposed
adjacent a light source with a light collimating optical
element.
[0034] FIG. 26 is a perspective view of one embodiment of a light
emitting device comprising light coupling lightguides and a light
source oriented at an angle to the x, y, and z axis.
[0035] FIG. 27 is a perspective view of one embodiment of a light
emitting device wherein the coupling lightguides are optically
coupled to a surface of a lightguide.
[0036] FIG. 28 is a perspective view of one embodiment of a light
emitting device wherein the coupling lightguides are optically
coupled to the edge of a lightguide.
[0037] FIG. 29a is a perspective view of one embodiment for
manufacturing a light input coupler comprising an array of coupling
lightguides that are substantially within the same plane as the
lightguide and the coupling lightguides are regions of a light
transmitting film comprising two linear fold regions.
[0038] FIG. 29b is a perspective view of one embodiment for
manufacturing an input coupler and lightguide comprising
translating one of the linear fold regions of FIG. 29a.
[0039] FIG. 29c is a perspective view of one embodiment for
manufacturing an input coupler and lightguide comprising
translating one of the linear fold regions of FIG. 29b.
[0040] FIG. 29d is a perspective view of one embodiment for
manufacturing an input coupler and lightguide comprising
translating one of the linear fold regions of FIG. 29c.
[0041] FIG. 29e is a perspective view of one embodiment for
manufacturing an input coupler and lightguide comprising
translating one of the linear fold regions of FIG. 29d.
[0042] FIG. 30 is a cross-sectional side view of a region of one
embodiment of a reflective display comprising a backlight disposed
between the light modulating pixels and the reflective element.
[0043] FIG. 31 is a top view of one embodiment of an input coupler
and lightguide wherein the array of coupling lightguides has
non-parallel regions.
[0044] FIG. 32 is a perspective top view of a portion of the input
coupler and lightguide of FIG. 31 with the coupling lightguides
folded.
[0045] FIG. 33 is a perspective view of one embodiment of a light
input coupler and lightguide comprising a relative position
maintaining element disposed proximate a linear fold region.
[0046] FIG. 34 is a top view of one embodiment of a light input
coupler and lightguide comprising bundles of coupling lightguides
that are folded twice and recombined in a plane substantially
parallel to the film-based lightguide.
[0047] FIG. 35a is a top view of one embodiment of a light input
coupler and lightguide comprising bundles of coupling lightguides
that are folded upwards (+z direction) and combined in a stack that
is substantially perpendicular to the plane of the film-based
lightguide.
[0048] FIG. 35b is a magnification of the region of FIG. 35a
comprising the upward folds of the coupling lightguides.
[0049] FIG. 36 is a top view of one embodiment of a light emitting
device comprising a lenticular lens array film.
[0050] FIG. 37 is a cross-sectional side view of one embodiment of
a lenticular lens array film comprising light extraction
features.
[0051] FIG. 38 is a cross-scetional side view of a section of one
embodiment of a display comprising a multi-layer lenticular lens
array film.
[0052] FIG. 39 is a top view of one embodiment of a light emitting
device with an un-folded lightguide comprising fold regions.
[0053] FIG. 40 is a perspective view of the light emitting device
of FIG. 39 with the lightguide being folded.
[0054] FIG. 41 is a perspective view of the light emitting device
of FIG. 39 folded with the lightguide comprising overlapping folded
regions. FIG. 42 is an elevated view of one embodiment of a
film-based lightguide comprising a first light emitting region
disposed to receive light from a first set of coupling lightguides
and a second light emitting region disposed to receive light from a
second set of coupling lightguides.
[0055] FIG. 43 is an elevated view of the film-based lightguide of
FIG. 42 with the lightguides folded.
[0056] FIG. 44 is a cross-sectional side view of one embodiment of
a light emitting device with optical redundancy comprising two
lightguides stacked in the z direction.
[0057] FIG. 45 is a cross-sectional side view of one embodiment of
a light emitting device with a first light source and a second
light source thermally coupled to a first thermal transfer
element.
[0058] FIG. 46 is a top view of one embodiment of a light emitting
device comprising coupling lightguides with a plurality of first
reflective surface edges and a plurality of second reflective
surface edges within each coupling lightguide.
[0059] FIG. 47 is an enlarged perspective view of the input end of
the coupling lightguides of FIG. 46.
[0060] FIG. 48 is a cross-sectional side view of the coupling
lightguides and light source of one embodiment of a light emitting
device comprising index matching regions disposed between the core
regions of the coupling lightguides.
[0061] FIG. 49 is a top view of one embodiment of a film-based
lightguide comprising an array of tapered coupling lightguides.
[0062] FIG. 50 is a perspective top view of a light emitting device
of one embodiment comprising the film-based lightguide of FIG. 49
and a light source.
[0063] FIG. 51 is a perspective top view of an embodiment of a
light emitting device comprising the light emitting device of FIG.
50 wherein the tapered coupling lightguides and light source are
folded behind the light emitting region.
[0064] FIG. 52 is a top view of one embodiment of a film-based
lightguide comprising an array of angled, tapered coupling
lightguides.
[0065] FIG. 53 is a perspective top view of a light emitting device
of one embodiment comprising the film-based lightguide of FIG.
52.
[0066] FIG. 54 is a top view of one embodiment of a film-based
lightguide comprising a first and second array of angled, tapered
coupling lightguides.
[0067] FIG. 55 is a perspective top view of a light emitting device
of one embodiment comprising the film-based lightguide of FIG.
54.
[0068] FIG. 56 is a top view of one embodiment of a light emitting
device comprising a lightguide, coupling lightguides and a curved
mirror.
[0069] FIG. 57 is a top view of one embodiment of a light emitting
device comprising a lightguide, coupling lightguides, and a curved
mirror with two curved regions.
[0070] FIG. 58 is a top view of one embodiment of a light emitting
device comprising a lightguide and two light input couplers
comprising coupling lightguides that have been folded behind the
light emitting region of the light emitting device.
[0071] FIG. 59 is a top view of one embodiment of a light emitting
device comprising a lightguide with coupling lightguides on two
orthogonal sides.
[0072] FIG. 60 is a cross-sectional side view of a portion of a
light emitting device of one embodiment comprising a lightguide and
a light input coupler wherein a low contact area cover is
physically coupled to the light input coupler.
[0073] FIG. 61 shows an enlarged portion of FIG. 60 of the region
of the lightguide in contact with the low contact area cover.
[0074] FIG. 62 is a side view of a portion of a light emitting
device of one embodiment comprising a lightguide and a light input
coupler protected by a low contact area cover.
[0075] FIG. 63 is a perspective view of a portion of a film-based
lightguide of one embodiment comprising coupling lightguides
comprising two flanges on either side of the end region of the
coupling lightguides.
[0076] FIG. 64 is a perspective view of one embodiment of a
film-based lightguide comprising a light input coupler and
lightguide comprising a relative position maintaining element
disposed proximal to a linear fold region.
[0077] FIG. 65 is a perspective view of one embodiment of relative
position maintaining element comprising rounded angled edge
surfaces.
[0078] FIG. 66 is a perspective view of one embodiment of relative
position maintaining element comprising rounded angled edge
surfaces and a rounded tip.
[0079] FIG. 67 is a perspective view of a portion of a film-based
lightguide of one embodiment comprising coupling lightguides
comprising two flanges on either side of the end region of the
coupling lightguides.
[0080] FIG. 68 is a perspective view of a portion of the light
emitting device of the embodiment illustrated in FIG. 62.
[0081] FIG. 69 is a top view of one embodiment of a light emitting
device with two light input couplers, a first light source, and a
second light source disposed on opposite sides of a lightguide.
[0082] FIG. 70 is a perspective view of one embodiment of a light
emitting device comprising a lightguide, a light input coupler, and
a light reflecting film disposed between the light input coupler
and the light emitting region.
[0083] FIG. 71 is a top view of a region of one embodiment of a
light emitting device comprising a stack of coupling lightguides
disposed to receive light from a light collimating optical element
and a light source.
[0084] FIG. 72 is a cross-sectional side view of the embodiment
shown in FIG. 71.
[0085] FIG. 73 is a top view of a region of one embodiment of a
light emitting device comprising a stack of coupling lightguides
physically coupled to a collimating optical element.
[0086] FIG. 74 is a top view of a region of one embodiment of a
light emitting device comprising a light source adjacent a light
turning optical element optically coupled to a stack of coupling
lightguides.
[0087] FIG. 75a is a top view of a region of one embodiment of a
light emitting device comprising a light source disposed adjacent a
lateral edge of a stack of coupling lightguides with light turning
optical edges.
[0088] FIG. 75b is a top view of a region of one embodiment of a
light emitting device comprising a light source disposed adjacent
the light input surface edge of the extended region of a stack of
coupling lightguides with light turning optical edges.
[0089] FIG. 76 is a top view of a region of one embodiment of a
light emitting device comprising a light source disposed to couple
light into two light turning optical elements that are optically
coupled to two stacks of coupling lightguides using an optical
adhesive.
[0090] FIG. 77 is a top view of a region of one embodiment of a
light emitting device comprising a light source disposed to couple
light into a bi-directional light turning optical element optically
coupled to two stacks of coupling lightguides.
[0091] FIG. 78 is a top view of a region of one embodiment of a
light emitting device comprising two light sources disposed to
couple light into a bi-directional light turning optical element
optically coupled to two stacks of coupling lightguides.
[0092] FIG. 79 is a top view of a region of one embodiment of a
light emitting device comprising a light source disposed to couple
light into two stacks of coupling lightguides with light turning
optical edges.
[0093] FIG. 80 is a top view of a region of one embodiment of a
light emitting device comprising a light source disposed to couple
light into two overlapping stacks of coupling lightguides with
light turning optical edges.
[0094] FIG. 81 is a top view of a region of one embodiment of a
light emitting device comprising a light source disposed to couple
light into a stack of coupling lightguides with light turning
optical edges wherein the coupling lightguides have tabs with tab
alignment holes.
[0095] FIG. 82 is a top view of a region of one embodiment of a
light emitting device comprising a light source disposed to couple
light into a stack of coupling lightguides with light turning
optical edges and registration holes in a low light flux density
region.
[0096] FIG. 83 is a top view of a region of one embodiment of a
light emitting device comprising a light source disposed to couple
light into a stack of coupling lightguides with a light source
overlay tab region for light source registration.
[0097] FIG. 84 is a top view of one embodiment of a lightguide
comprising coupling lightguides with light turning optical
edges.
[0098] FIG. 85 is a top view of one embodiment of a light emitting
device comprising the lightguide of FIG. 84 with the coupling
lightguides folded such that they extend past a lateral edge.
[0099] FIG. 86 is a top view of one embodiment of a lightguide
comprising a non-folded coupling lightguide.
[0100] FIG. 87 is a top view of one embodiment of a light emitting
device comprising the lightguide of FIG. 86 wherein the coupling
lightguides are folded.
[0101] FIG. 88 is a top view of one embodiment of a lightguide
comprising coupling lightguides with light collimating optical edge
regions and light turning optical edge regions.
[0102] FIG. 89 is a top view of one embodiment of a light emitting
device comprising the film-based lightguide of FIG. 88 wherein
coupling lightguides are folded.
[0103] FIG. 90 is a top view of one embodiment of a lightguide
comprising coupling lightguides with extended regions.
[0104] FIG. 91 is a top view of one embodiment of the lightguide of
FIG. 90 with the coupling lightguides folded.
[0105] FIG. 92 is a top view of one embodiment of a lightguide
comprising coupling lightguides with light turning optical edges
turning light in two directions and a non-folded coupling
lightguide.
[0106] FIG. 93 is a perspective top view of one embodiment of a
light emitting device comprising the film-based lightguide of FIG.
92 with the coupling lightguides from each side grouped
together.
[0107] FIG. 94 is a perspective top view of one embodiment of a
light emitting device comprising the film-based lightguide of FIG.
92 with the coupling lightguides from the sides interleaved in a
stack.
[0108] FIG. 95 is a top view of one embodiment of a film-based
lightguide comprising coupling lightguides with light turning
optical edges extended in shapes inverted along a first
direction.
[0109] FIG. 96 is a perspective view of a lightguide comprising one
embodiment of the lightguide of FIG. 95 folded to form two stacks
of coupling lightguides.
[0110] FIG. 97 is a top view of one embodiment of a film-based
lightguide comprising coupling lightguides with light turning
optical edges, light collimating optical edges, and light source
overlay tab regions comprising alignment cavities.
[0111] FIG. 98 is a top view of one embodiment of a light emitting
device comprising the film-based lightguide of FIG. 97 folded to a
stack of coupling lightguides positioned over alight source and
guided in the z direction by an alignment guide.
[0112] FIG. 99 is a side view of the light emitting device
embodiment of FIG. 98 in the region near the light source.
[0113] FIG. 100 is a side view of a region of one embodiment of a
light emitting device with coupling lightguides with alignment
cavities that do not extend to fit completely over the alignment
guide.
[0114] FIG. 101 is a cross-sectional side view of a region of one
embodiment of a light emitting device comprising coupling
lightguides with interior light directing edges.
[0115] FIG. 102 is a cross-sectional side view of one embodiment of
a light emitting display comprising a reflective spatial light
modulator and a film-based lightguide frontlight adhered to a
flexible connector.
[0116] FIG. 103 is a cross-sectional side view of one embodiment of
a light emitting display comprising a lightguide that further
functions as a top substrate for a reflective spatial light
modulator.
[0117] FIG. 104 is a perspective view of one embodiment of a light
emitting device comprising a film-based lightguide that further
functions as a top substrate for the reflective spatial light
modulator with the light source disposed on a circuit board
physically coupled to the flexible connector.
[0118] FIG. 105 is a perspective view of one embodiment of a light
emitting display comprising a reflective spatial light modulator
and a film-based lightguide adhered to a flexible connector with
the light source physically coupled to a flexible connector.
[0119] FIG. 106 is a cross-sectional side view of one embodiment of
a display comprising the light emitting device of FIG. 104 further
comprising a flexible touchscreen.
[0120] FIG. 107 is a perspective view of one embodiment of a light
emitting device with the flexible touchscreen between the
film-based lightguide and the reflective spatial light
modulator.
[0121] FIG. 108 is a perspective view of one embodiment of a
reflective display comprising a flexible display driver connector
and a flexible film-based lightguide frontlight.
[0122] FIG. 109 is a perspective view of one embodiment of a
reflective display comprising a flexible display driver connector
and a flexible film-based lightguide frontlight with a light source
disposed on a flexible touchscreen film.
[0123] FIG. 110 is a top view of one embodiment of a film-based
lightguide comprising an array of coupling lightguides wherein each
coupling lightguide further comprises a sub-array of coupling
lightguides.
[0124] FIG. 111 is a perspective top view of one embodiment of a
light emitting device comprising the film-based lightguide of FIG.
110 wherein the coupling lightguides are folded.
[0125] FIG. 112 is a cross-sectional side view of a region of one
embodiment of a light emitting device comprising a stacked array of
coupling lightguides with core regions comprising vertical light
turning optical edges.
[0126] FIG. 113 is a cross-sectional side view of a region of one
embodiment of a light emitting device comprising a stacked array of
coupling lightguides with core regions comprising vertical light
turning optical edges and vertical light collimating optical
edges.
[0127] FIG. 114 is a cross-sectional side view of a region of one
embodiment of a light emitting device comprising a stacked array of
coupling lightguides with a cavity and core regions comprising
vertical light turning optical edges and light collimating optical
edges
[0128] FIG. 115 is a perspective view of a region of one embodiment
of a light emitting device comprising a stacked array of coupling
lightguides disposed within an alignment cavity of a thermal
transfer element.
[0129] FIG. 116 is a side view of a region of one embodiment of a
light emitting device comprising a stacked array of coupling
lightguides disposed within an alignment guide with an extended
alignment arm and an alignment cavity.
[0130] FIG. 117 is a perspective view of one embodiment of a light
emitting device comprising film-based lightguide and a light
reflecting optical element that is also a light collimating optical
element and light blocking element.
DETAILED DESCRIPTION
[0131] The features and other details of several embodiments will
now be more particularly described. It will be understood that
particular embodiments described herein are shown by way of
illustration and not as limitations. The principal features can be
employed in various embodiments without departing from the scope of
any particular embodiment. All parts and percentages are by weight
unless otherwise specified.
DEFINITIONS
[0132] "Electroluminescent sign" is defined herein as a means for
displaying information wherein the legend, message, image or
indicia thereon is formed by or made more apparent by an
electrically excitable source of illumination. This includes
illuminated cards, transparencies, pictures, printed graphics,
fluorescent signs, neon signs, channel letter signs, light box
signs, bus-stop signs, illuminated advertising signs, EL
(electroluminescent) signs, LED signs, edge-lit signs, advertising
displays, liquid crystal displays, electrophoretic displays, point
of purchase displays, directional signs, illuminated pictures, and
other information display signs. Electroluminescent signs can be
self-luminous (emissive), back-illuminated (back-lit), front
illuminated (front-lit), edge-illuminated (edge-lit),
waveguide-illuminated or other configurations wherein light from a
light source is directed through static or dynamic means for
creating images or indicia.
[0133] "Optically coupled" as defined herein refers to coupling of
two or more regions or layers such that the light passing from one
region to the other is not substantially reduced by Fresnel
interfacial reflection losses due to differences in refractive
indices between the regions. "Optical coupling" methods include
methods of coupling wherein the two regions coupled together have
similar refractive indices or using an optical adhesive with a
refractive index substantially near or between the refractive index
of the regions or layers. Examples of "optical coupling" include,
without limitation, lamination using an index-matched optical
adhesive, coating a region or layer onto another region or layer,
or hot lamination using applied pressure to join two or more layers
or regions that have substantially close refractive indices.
Thermal transferring is another method that can be used to
optically couple two regions of material. Forming, altering,
printing, or applying a material on the surface of another material
are other examples of optically coupling two materials. "Optically
coupled" also includes forming, adding, or removing regions,
features, or materials of a first refractive index within a volume
of a material of a second refractive index such that light
propagates from the first material to the second material. For
example, a white light scattering ink (such as titanium dioxide in
a methacrylate, vinyl, or polyurethane based binder) may be
optically coupled to a surface of a polycarbonate or silicone film
by inkjet printing the ink onto the surface. Similarly, a light
scattering material such as titanium dioxide in a solvent applied
to a surface may allow the light scattering material to penetrate
or adhere in close physical contact with the surface of a
polycarbonate or silicone film such that it is optically coupled to
the film surface or volume.
[0134] "Light guide" or "waveguide" refers to a region bounded by
the condition that light rays propagating at an angle that is
larger than the critical angle will reflect and remain within the
region. In a light guide, the light will reflect or TIR (totally
internally reflect) if the angle (.alpha.) satisfies the
condition
a > sin - 1 ( n 2 n 1 ) , ##EQU00001##
where n.sub.1 is the refractive index of the medium inside the
light guide and n.sub.2 is the refractive index of the medium
outside the light guide. Typically, n.sub.2 is air with a
refractive index of n.apprxeq.1; however, high and low refractive
index materials can be used to achieve light guide regions. The
light guide may comprise reflective components such as reflective
films, aluminized coatings, surface relief features, and other
components that can re-direct or reflect light. The light guide may
also contain non-scattering regions such as substrates. Light can
be incident on a lightguide region from the sides or below and
surface relief features or light scattering domains, phases or
elements within the region can direct light into larger angles such
that it totally internally reflects or into smaller angles such
that the light escapes the light guide. The light guide does not
need to be optically coupled to all of its components to be
considered as a light guide. Light may enter from any face (or
interfacial refractive index boundary) of the waveguide region and
may totally internally reflect from the same or another refractive
index interfacial boundary. A region can be functional as a
waveguide or lightguide for purposes illustrated herein as long as
the thickness is larger than the wavelength of light of interest.
For example, a light guide may be a 5 micron region or layer of a
film or it may be a 3 millimeter sheet comprising a light
transmitting polymer.
[0135] "In contact" and "disposed on" are used generally to
describe that two items are adjacent one another such that the
whole item can function as desired. This may mean that additional
materials can be present between the adjacent items, as long as the
item can function as desired.
[0136] A "film" as used herein refers to a thin extended region,
membrane, or layer of material.
[0137] A "bend" as used herein refers to a deformation or
transformation in shape by the movement of a first region of an
element relative to a second region, for example. Examples of bends
include the bending of a clothes rod when heavy clothes are hung on
the rod or rolling up a paper document to fit it into a cylindrical
mailing tube. A "fold" as used herein is a type of bend and refers
to the bend or lay of one region of an element onto a second region
such that the first region covers the second region. An example of
a fold includes bending a letter and forming creases to place it in
an envelope. A fold does not require that all regions of the
element overlap. A bend or fold may be a change in the direction
along a first direction along a surface of the object. A fold or
bend may or may not have creases and the bend or fold may occur in
one or more directions or planes such as 90 degrees or 45 degrees.
A bend or fold may be lateral, vertical, torsional, or a
combination thereof.
Light Emitting Device
[0138] In one embodiment, a light emitting device comprises a first
light source, a light input coupler, a light mixing region, and a
lightguide comprising a light emitting region with a light
extraction feature. In one embodiment, the first light source has a
first light source emitting surface, the light input coupler
comprises an input surface disposed to receive light from the first
light source and transmit the light through the light input coupler
by total internal reflection through a plurality of coupling
lightguides. In this embodiment, light exiting the coupling
lightguides is re-combined and mixed in a light mixing region and
directed through total internal reflection within a lightguide or
lightguide region. Within the lightguide, a portion of incident
light is directed within the light extracting region by light
extracting features into a condition whereupon the angle of light
is less than the critical angle for the lightguide and the directed
light exits the lightguide through the lightguide light emitting
surface.
[0139] In a further embodiment, the lightguide is a film with light
extracting features below a light emitting device output surface
within the film and film is separated into coupling lightguide
strips which are folded such that they form a light input coupler
with a first input surface formed by the collection of edges of the
coupling lightguides.
[0140] In one embodiment, the light emitting device has an optical
axis defined herein as the direction of peak luminous intensity for
light emitting from the light emitting surface or region of the
device for devices with output profiles with one peak. For optical
output profiles with more than one peak and the output is
symmetrical about an axis, such as with a "batwing" type profile,
the optical axis of the light emitting device is the axis of
symmetry of the light output. In light emitting devices with
angular luminous intensity optical output profiles with more than
one peak which are not symmetrical about an axis, the light
emitting device optical axis is the angular weighted average of the
luminous intensity output. For non-planar output surfaces, the
light emitting device optical axis is evaluated in two orthogonal
output planes and may be a constant direction in a first output
plane and at a varying angle in a second output plane orthogonal to
the first output plane. For example, light emitting from a
cylindrical light emitting surface may have a peak angular luminous
intensity (thus light emitting device optical axis) in a light
output plane that does not comprise the curved output surface
profile and the angle of luminous intensity could be substantially
constant about a rotational axis around the cylindrical surface in
an output plane comprising the curved surface profile, and thus the
peak angular intensity is a range of angles. When the light
emitting device has a light emitting device optical axis in a range
of angles, the optical axis of the light emitting device comprises
the range of angles or an angle chosen within the range. The
optical axis of a lens or element is the direction of which there
is some degree of rotational symmetry in at least one plane and as
used herein corresponds to the mechanical axis. The optical axis of
the region, surface, area, or collection of lenses or elements may
differ from the optical axis of the lens or element, and as used
herein is dependent on the incident light angular and spatial
profile, such as in the case of off-axis illumination of a lens or
element.
Light Input Coupler
[0141] In one embodiment, a light input coupler comprises a
plurality of coupling lightguides disposed to receive light
emitting from a light source and channel the light into a
lightguide. In one embodiment, the plurality of coupling
lightguides are strips cut from a lightguide film such that they
remain un-cut on at least one edge but can be rotated or positioned
(or translated) substantially independently from the lightguide to
couple light through at least one edge or surface of the strip. In
another embodiment, the plurality of coupling lightguides are not
cut from the lightguide film and are separately optically coupled
to the light source and the lightguide. In one embodiment, the
light input coupler comprises at least one light source optically
coupled to the coupling lightguides which join together in a light
mixing region. In another embodiment, the light input coupler is a
collection of strip sections cut from a region film which are
arranged in a grouping such that light may enter through the edge
of a grouping or arrangement of strips. In another embodiment, the
light emitting device comprises a light input coupler comprising a
core region of a core material and a cladding region or cladding
layer of a cladding material on at least one face or edge of the
core material with a refractive index less than the core material.
In other embodiment, the light input coupler comprises a plurality
of coupling lightguides wherein a portion of light from a light
source incident on the face of at least one strip is directed into
the lightguide such that it propagates in a waveguide condition.
The light input coupler may also comprise at least one selected
from the group: a strip folding device, a strip holding element,
and an input surface optical element.
Light Source
[0142] In one embodiment, a light emitting device comprises at
least one light source selected from a group: fluorescent lamp,
cylindrical cold-cathode fluorescent lamp, flat fluorescent lamp,
light emitting diode, organic light emitting diode, field emissive
lamp, gas discharge lamp, neon lamp, filament lamp, incandescent
lamp, electroluminescent lamp, radiofluorescent lamp, halogen lamp,
incandescent lamp, mercury vapor lamp, sodium vapor lamp, high
pressure sodium lamp, metal halide lamp, tungsten lamp, carbon arc
lamp, electroluminescent lamp, laser, photonic bandgap based light
source, quantum dot based light source, high efficiency plasma
light source, microplasma lamp. The light emitting device may
comprise a plurality of light sources arranged in an array, on
opposite sides of lightguide, on orthogonal sides of a lightguide,
on 3 or more sides of a lightguide, or on 4 sides of a
substantially planer lightguide. The array of light sources may be
a linear array with discrete LED packages comprises at least one
LED die. In another embodiment, a light emitting device comprises a
plurality of light sources within one package disposed to emit
light toward a light input surface. In one embodiment, the light
emitting device comprises 1, 2, 3, 4, 5, 6, 8, 9, 10, or more than
10 light sources.
[0143] In one embodiment, a light emitting device comprises at
least one broadband light source that emits light in a wavelength
spectrum larger than 100 nanometers. In another embodiment, a light
emitting device comprises at least one narrowband light source that
emits light in a narrow bandwidth less than 100 nanometers. In
another embodiment, a light emitting device comprises at least one
broadband light source that emits light in a wavelength spectrum
larger than 100 nanometers or at least one narrowband light source
that emits light in a narrow bandwidth less than 100 nanometers. In
one embodiment a light emitting device comprises at least one
narrowband light source with a peak wavelength within a range
selected from the group: 300 nm-350 nm, 350 nm-400 nm, 400 nm-450
nm, 450 nm-500 nm, 500 nm-550 nm, 550 nm-600 nm, 600 nm-650 nm, 650
nm-700 nm, 700 nm-750 nm, 750 nm-800 nm, and 800 nm-1200 nm. The
light sources may be chosen to match the spectral qualities of red,
green and blue such that collectively when used in a light emitting
device used as a display, the color gamut area is at least one
selected from the group: 70% NTSC, 80% MSC, 90% NTSC, 100% NTSC,
and 60%, 70%, 80%, 90%, and 95% of the visible CAE u' v' color
gamut of a standard viewer. In one embodiment, at least one light
source is a white LED package comprising a red, green, and blue
LED.
[0144] In another embodiment, at least two light sources with
different colors are disposed to couple light into the lightguide
through at least one light input coupler. In another embodiment, a
light emitting device comprises at least three light input
couplers, at least three light sources with different colors (red,
green and blue for example) and at least three lightguides. In
another embodiment, a light source further comprises at least one
selected from the group: reflective optic, reflector, reflector
cup, collimator, primary optic, secondary optic, collimating lens,
compound parabolic collimator, lens, reflective region, and input
coupling optic. The light source may also comprise an optical path
folding optic such as a curved reflector that can enable the light
source and possibly heat-sink) to be oriented along a different
edge of the light emitting device. The light source may also
comprise a photonic bandgap structure, nano-structure or other
three-dimensional arrangement that provides light output with an
angular FWHM less than one selected from the group: 120 degrees,
100 degrees, 80 degrees, 60 degrees, 40 degrees, and 20
degrees.
[0145] In another embodiment, a light emitting device comprises a
light source emitting light in an angular full-width at half
maximum intensity of less than one selected from 150 degrees, 120
degrees, 100 degrees, 80 degrees, 70 degrees, 60 degrees, 50
degrees, 40 degrees, 30 degrees, 20 degrees, and 10 degrees. In
another embodiment, the light source further comprises at least one
selected from the group: primary optic, secondary optic, and
photonic bandgap region, and the angular full-width at half maximum
intensity of the light source is less than one selected from 150
degrees, 120 degrees, 100 degrees, 80 degrees, 70 degrees, 60
degrees, 50 degrees, 40 degrees, 30 degrees, 20 degrees, and 10
degrees.
LED Array
[0146] In one embodiment, the light emitting device comprises a
plurality of LEDs or LED packages wherein the plurality of LEDs or
LED packages comprises an array of LEDs. The array components (LEDs
or electrical components) may be physically (and/or electrically)
coupled to a single circuit board or they may be coupled to a
plurality of circuit boards that may or may not be directly
physically coupled (i.e. such as not on the same circuit board). In
one embodiment, the array of LEDs is an array comprising at least
two selected from the group: red, green, blue, and white LEDs. In
this embodiment, the variation in the white point due to
manufacturing or component variations can be reduced. In another
embodiment, the LED array comprises at least one cool white LED and
one red LED. In this embodiment, the CRI, or Color Rendering Index,
is higher than the cool white LED illumination alone. In one
embodiment, the CRI of at least one selected from the group: a
light emitting region, the light emitting surface, light fixture,
light emitting device, display driven in a white mode comprising
the light emitting device, and sign is greater than one selected
from the group: 70, 75, 80, 85, 90, 95, and 99. In another
embodiment, the NIST Color Quality Scale (CQS) of at least one
selected from the group: a light emitting region, the light
emitting surface, light fixture, light emitting device, display
driven in a white mode comprising the light emitting device, or
sign is greater than one selected from the group: 70, 75, 80, 85,
90, 95, and 99. In another embodiment, a display comprising the
light emitting device has a color gamut greater than 70%, 80%, 85%,
90%, 95%, 100%, 105%, 110%, 120%, and 130% that of the NTSC
standard. In another embodiment, the LED array comprises white,
green, and red LEDs. In another embodiment, the LED array comprises
at least one green and blue LED and two types of red LEDs with one
type having a lower luminous efficacy or a lower wavelength than
the other type of red LED. As used herein, the white LED may be a
phosphor converted blue LED or a phosphor converted UV LED.
[0147] In another embodiment, the input array of LEDs can be
arranged to compensate for uneven absorption of light through
longer verses shorter lightguides. In another embodiment, the
absorption is compensated for by directing more light into the
light input coupler corresponding to the longer coupling
lightguides or longer lightguides. In another embodiment, light
within a first wavelength band is absorbed within the lightguide
more than light within a second wavelength band and a first ratio
of the radiant light flux coupled into the light input coupler
within the first wavelength band divided by the radiant light flux
coupled into the light input coupler within the second wavelength
band is greater than a second ratio of the radiant light flux
emitted from the light emitting region within the first wavelength
band divided by the radiant light flux emitted from the light
emitting region within the second wavelength band.
LED Array Location
[0148] In one embodiment, a plurality of LED arrays are disposed to
couple light into a single light input coupler or more than one
light input coupler. In a further embodiment, a plurality of LEDs
disposed on a circuit board are disposed to couple light into a
plurality of light input couplers that direct light toward a
plurality of sides of a light emitting device comprising a light
emitting region. In a further embodiment, a light emitting device
comprises an LED array and light input coupler folded behind the
light emitting region of the light emitting device such that the
LED array and light input coupler are not visible when viewing the
center of the light emitting region at an angle perpendicular to
the surface. In another embodiment, a light emitting device
comprises a single LED array disposed to couple light into at least
one light input coupler disposed to direct light into the light
emitting region from the bottom region of a light emitting device.
In one embodiment, a light emitting device comprises a first LED
array and a second LED array disposed to couple light into a first
light input coupler and a second light input coupler, respectively,
wherein the first light input coupler and second light input
coupler are disposed to direct light into the light emitting region
from the top region and bottom region, respectively, of a light
emitting device. In a further embodiment, a light emitting device
comprises a first LED array, a second LED array, and a third LED
array, disposed to couple light into a first light input coupler, a
second light input coupler, and a third light input coupler,
respectively, disposed to direct light into the light emitting
region from the bottom region, left region, and right region,
respectively, of a light emitting device. In another embodiment, a
light emitting device comprises a first LED array, a second LED
array, a third LED array, and a fourth LED array, disposed to
couple light into a first light input coupler, a second light input
coupler, a third light input coupler, and a fourth light input
coupler, respectively, disposed to direct light into the light
emitting region from the bottom region, left region, right region,
and top region, respectively, of a light emitting device.
Wavelength Conversion Material
[0149] In another embodiment, the LED is a blue or ultraviolet LED
combined with a phosphor. In another embodiment, a light emitting
device comprises a light source with a first activating energy and
a wavelength conversion material which converts a first portion of
the first activating energy into a second wavelength different than
the first. In another embodiment, the light emitting device
comprises at least one wavelength conversion material selected from
the group: a fluorophore, phosphor, a fluorescent dye, an inorganic
phosphor, photonic bandgap material, a quantum dot material, a
fluorescent protein, a fusion protein, a fluorophores attached to
protein to specific functional groups (such as amino groups (active
ester, carboxylate, isothiocyanate, hydrazine), carboxyl groups
(carbodiimide), thiol (maleimide, acetyl bromide), azide (via click
chemistry or non-specifically (glutaraldehyde))), quantum dot
fluorophores, small molecule fluorophores, aromatic fluorophores,
conjugated fluorophores, a fluorescent dye, and other wavelength
conversion material.
[0150] In one embodiment, the light source comprises a
semiconductor light emitter such as an LED and a wavelength
conversion material that converts a portion of the light from the
emitter to a shorter or longer wavelength. In another embodiment,
at least one selected from the group: light input coupler, cladding
region, coupling lightguide, input source optic, coupling optic,
light mixing region, lightguide, light extraction feature or
region, and light emitting surface comprises a wavelength
conversion material.
Light Input Coupler Input Surface
[0151] In one embodiment, the light input coupler comprises a
collection of coupling lightguides with a plurality of edges
forming a light coupler input surface. In another embodiment, an
optical element is disposed between the light source and at least
one coupling lightguide wherein the optical element receives light
from the light source through a light coupler input surface. In
some embodiments, the input surface is substantially polished,
flat, or optically smooth such that light does not scatter forwards
or backwards from pits, protrusions or other rough surface
features. In some embodiments, an optical element is disposed to
between the light source and at least one coupling lightguide to
provide light redirection as an input surface (when optically
coupled to at least one coupling lightguide) or as an optical
element separate or optically coupled to at least one coupling
lightguide such that more light is redirected into the lightguide
at angles greater than the critical angle within the lightguide
than would be the case without the optical element or with a flat
input surface, in another embodiment, the input surface is curved
to refract light more light received from the light source into
angles within the lightguide greater than the critical angle within
the lightguide than would occur with a flat input surface. In
another embodiment, the optical element comprises radial or linear
Fresnel lens features which refract incident light. In another
embodiment, the optical element comprises a refractive-TIR hybrid
Fresnel lens (such as one having a low F/# of less than 1.5). In a
further embodiment, the optical element is a reflective and
refractive optical element. In one embodiment, the light input
surface may be formed by machine, cutting, polishing, forming,
molding, or otherwise removing or adding material to the lightguide
couplers to create a smooth, curved, rounded, concave, convex,
rigged, grooved, micro-structured, nano-structured, or
predetermined surface shape. In another embodiment, the light input
coupler comprises an optical element designed to collect light from
the light source and increase the uniformity. Such optical elements
can include fly's eye lenses, microlens arrays, integral lenses,
lenticular lenses holographic or other diffusing elements with
micro-scale features or nano-scale features independent of how they
were formed. In another embodiment, the light input coupler is
optically coupled to at least one lightguide and at least one light
source. In another embodiment, the optical element is at least one
selected from the group: diffractive element, holographic element,
lenticular element, lens, planar window, refractive element,
reflective element, waveguide coupling element, anti-reflection
coated element, planar element, and formed portion or region of at
least one selected from the group: coupling lightguide, optical
adhesive, UV cured adhesive, and pressure sensitive adhesive. The
light coupler or an element therein may be comprised of at least
one light transmitting material. In another embodiment, an element
of the light input coupler or the light input window, lens or
surface is a silicone material wherein the ASTM D1003 luminous
transmittance change due to exposure to 150 degrees centigrade for
200 hours is less than one selected from the group: 0.5%, 1%, 2%,
3%, 4%, and 5%. In another embodiment, the input surface of the
coupling lightguides, the coupling lightguides, or the window
optically coupled to the input surface is optically coupled using a
light transmitting optical adhesive to one or more selected from
the group: an optical window, a light source, the outer surface of
an LED, a light collimating optical element, a light redirecting
optical element, a light turning optical element, an intermediate
lens, or a light transmitting optical element.
[0152] When light propagating in air is incident to a planar light
input surface of a light transmitting material with a refractive
index higher than 1.3 at high angles from the normal to the
interface, for example, much of the light is reflected from the
air-input surface interface. One method of reducing the loss of
light due to reflection is to optically couple the input surface of
the light input coupler to the light source. Another method to
reduce this loss is to use a collimation optic or optic that
directs some of the light output from the light source into angles
closer to the optical axis of the light source. The collimating
optic, or optical element, may be optically coupled to the light
source, the coupling lightguides, an adhesive, or other optical
element such that it directs more light into the coupling
lightguides into a total internal reflection condition within the
coupling lightguides. In another embodiment, the light input
surface comprises a recessed cavity or concave region such that the
percentage of light from a light source disposed adjacent to the
cavity or concave region that is reflected from the input surface
is less than one selected from the group: 40%, 30%, 20%, 10%, 5%,
3%, and 2%.
[0153] In another embodiment, the total input area ratio, defined
as the total area of the input surface of all of the light input
couplers of the light emitting device receiving more than 5% of the
total light flux from any light source divided by the total light
emitting surface areas of the light sources is greater than one
selected from the group: 0.9, 1, 1.5, 2, 4, and 5. In another
embodiment, the individual input area ratio, defined as the area of
the input surface of a light input coupler of the light emitting
device receiving more than 5% of the total light flux received from
a light source divided by the light emitting surface area of the
light source is greater than one selected from the group: 0.9, 1,
1.5, 2, 4, and 5. The individual input area ratios of a light
emitting device may vary for different input couplers and the
individual input area ratio for a particular input coupler may be
greater or less than the total input area ratio.
Input Surface Position Relative to Light Source
[0154] In one embodiment, the distance between the outer surface of
the light source and the input surface of the light input coupler
is less than one selected from the group: 3 millimeters, 2
millimeters, 1 millimeter, 0.5 millimeters, and 0.25 millimeters
over a time period between just before powering on the light source
and the time for a substantially steady-state junction temperature
of the light source at a maintained ambient temperature for the
light emitting device of 20 degrees Celsius.
[0155] In one embodiment, an elastic object used to store
mechanical energy is disposed to force the outer surface of the
light source to be in contact or a predetermined distance from the
input surface of the light input coupler. In one embodiment, the
elastic object is one selected from the group: tension spring,
extension spring, compression spring, torsion spring, wire spring,
coiled spring, flat spring, cantilever spring, coil spring, helical
spring, conical spring, compression spring, volute spring,
hairspring, balance spring, leaf spring, V-spring, Belleville
washer, Belleville spring, constant-force spring, gas spring,
mainspring, rubber band, spring washer, a torsion bar twisted under
load, torsion spring, negator spring, and wave spring. In one
embodiment, the elastic object is disposed between the light source
or LED array and the housing or other element such as a thermal
transfer element such that a force is exerted against the light
source or LED array such that the relative distance between the
outer light emitting surface of the light source or LED array and
the input surface of the light input coupler remains within 0.5
millimeters of a fixed distance over a time period between just
before powering on the light source and the time for a
substantially steady-state junction temperature of the light source
at a maintained ambient temperature for the light emitting device
of 20 degrees Celsius.
[0156] In a further embodiment, a spacer comprises a physical
element that substantially maintains the minimum separation
distance of at least one light source and at least one input
surface of at least one light input coupler. In one embodiment, the
spacer is one selected from the group: a component of the light
source, a region of a film (such as a white reflective film or low
contact area cover film), a component of an LED array (such as a
plastic protrusion), a component of the housing, a component of a
thermal transfer element, a component of the holder, a component of
the relative position maintaining element, a component of the light
input surface, a component physically coupled to the light input
coupler, light input surface, at least one coupling lightguide,
window for the coupling lightguide, lightguide, housing or other
component of the light emitting device.
[0157] In a further embodiment, at least one selected from the
group: the film, lightguide, light mixing region, light input
coupler, and coupling lightguide comprises a relative position
maintaining mechanism that maintains the relative distance between
the outer light emitting surface of the light source or LED array
and the input surface of the light input coupler remains within 0.5
millimeters of a fixed distance over a time period between just
before powering on the light source and the time for a
substantially steady-state junction temperature of the light source
at a maintained ambient temperature for the light emitting device
of 20 degrees Celsius. In one embodiment, the relative position
maintaining mechanism is a hole in the lightguide and a pin in a
component (such as a thermal transfer element) physically coupled
to the light source. For example, pins in a thin aluminum sheet
thermal transfer element physically coupled to the light source are
registered into holes within the light input coupler (or a
component of the light input coupler such as a coupling lightguide)
to maintain the distance between the input surface of the light
input coupler and the light emitting surface of the light source.
In another embodiment, the relative position maintaining mechanism
is a guide device.
Stacked Strips or Segments of Film Forming a Light Input
Coupler
[0158] In one embodiment, the light input coupler is region of a
film that comprises the lightguide and the light input coupler
which comprises strip sections of the film which form coupling
lightguides that are grouped together to form a light coupler input
surface. The coupling lightguides may be grouped together such the
edges opposite the lightguide region are brought together to form
an input surface comprising of their thin edges. A planar input
surface for a light input coupler can provide beneficial refraction
to redirect a portion of the input light from the surface into
angles such that it propagates at angles greater than the critical
angle for the lightguide. In another embodiment, a substantially
planar light transmitting element is optically coupled to the
grouped edges of coupling lightguides. One or more of the edges of
the coupling lightguides may be polished, melted, adhered with an
optical adhesive, solvent welded, or otherwise optically coupled
along a region of the edge surface such that the surface is
substantially polished, smooth, flat, or substantially planarized.
This polishing can aide to reduce light scattering, reflecting, or
refraction into angles less than the critical angle within the
coupling lightguides or backwards toward the light source. The
light input surface may comprise a surface of the optical element,
the surface of an adhesive, the surface of more than one optical
element, the surface of the edge of one or more coupling
lightguides, or a combination of one or more of the aforementioned
surfaces. The light input coupler may also comprise an optical
element that has an opening or window wherein a portion of light
from a light source may directly pass into the coupling lightguides
without passing through the optical element. The light input
coupler or an element or region therein may also comprise a
cladding material or region.
[0159] In another embodiment, the cladding layer is formed in a
material wherein under at least one selected from the group: heat,
pressure, solvent, and electromagnetic radiation, a portion of the
cladding layer may be removed. In one embodiment, the cladding
layer has a glass transition temperature less than the core region
and pressure applied to the coupling lightguides near the light
input edges reduces the total thickness of the cladding to less
than one selected from the group: 10%, 20%, 40%, 60%, 80% and 90%
of the thickness of the cladding regions before the pressure is
applied. In another embodiment, the cladding layer has a glass
transition temperature less than the core region and heat and
pressure applied to the coupling lightguides near the light input
edges reduces the total thickness of the cladding regions to less
than one selected from the group: 10%, 20%, 40%, 60%, 80% and 90%
of the thickness of the cladding regions before the heat and
pressure is applied. In another embodiment, a pressure sensitive
adhesives functions as a cladding layer and the coupling
lightguides are folded such that the pressure sensitive adhesive or
component on one or both sides of the coupling lightguides holds
the coupling lightguides together and at least 10% of the thickness
of the pressure sensitive adhesive is removed from the light input
surface by applying heat and pressure.
Guide Device for Coupling the Light Source to the Light Input
Surface of the Light Input Coupler
[0160] The light input coupler may also comprise a guide that
comprises a mechanical, electrical, manual, guided, or other system
or component to facility the alignment of the light source in
relation to the light input surface. The guide device may comprise
an opening or window and may physically or optically couple
together one or more selected from the group: light source (or
component physically attached to a light source), a light input
coupler, coupling lightguide, housing, and electrical, thermal, or
mechanical element of the light emitting device. In one embodiment
of this device an optical element comprises one or more guides
disposed to physically couple or align the light source (such as an
LED strip) to the optical element or coupling lightguides. In
another embodiment, the optical element comprises one or more guide
regions disposed to physically couple or align the optical element
to the light input surface of the input coupler. The guide may
comprise a groove and ridge, hole and pin, male and corresponding
female component, or a fastener. In one embodiment, the guide
comprises a fastener selected from the group: a batten, button,
clamp, clasp, clip, clutch (pin fastener), flange, grommet, anchor,
nail, pin, peg, clevis pin, cotter linchpin, R-clip, retaining
ring, circlip retaining ring, c-ring retaining ring, rivet, screw
anchor, snap, staple, stitch, strap, tack, threaded fastener,
captive threaded fasteners (nut, screw, stud, threaded insert,
threaded rod), tie, toggle, hook-and-loop strips, wedge anchor, and
zipper. In another embodiment, one or more guide regions are
disposed to physically couple or align one or more films, film
segments (such as coupling lightguides), thermal transfer elements,
housing or other components of the light emitting device
together.
Light Redirecting Optical Element
[0161] In one embodiment, a light redirecting optical element is
disposed to receive light from at least one light source and
redirect the light into a plurality of coupling lightguides. In
another embodiment, the light redirecting optical element is at
least one selected from the group: secondary optic, mirrored
element or surface, reflective film such as aluminized PET, giant
birefringent optical films such as Vikuiti.TM. Enhanced Specular
Reflector Film by 3M Inc., curved mirror, totally internally
reflecting element, beamsplitter, and dichroic reflecting mirror or
film.
[0162] In another embodiment, a first portion of light from a light
source with a first wavelength spectrum is directed by reflection
by a wavelength selective reflecting element (such as a dichroic
filter) into a plurality of coupling lightguides. In another
embodiment, a first portion of light from a light source with a
first wavelength spectrum is directed by reflection by a wavelength
selective reflecting element (such as a dichroic filter) into a
plurality of coupling lightguides and a second portion of light
from a second light source with a second wavelength spectrum is
transmitted through the wavelength selective reflecting element
into the plurality of coupling lightguides. For example, in one
embodiment, a red light from an LED emitting red light is reflected
by a first dichroic filter oriented at 45 degrees and reflects
light into a set of coupling lightguides. Green light from an LED
emitting green light is reflected by a second dichroic filter
oriented at 45 degrees and passes through the first dichroic filter
into the set of coupling lightguides. Blue light from a blue LED is
directed toward and passes through the first and second dichroic
filters into the coupling lightguides. Other combinations of light
coupling or combining the output from multiple light sources into
an input surface or aperture are known in the field of projection
engine design and include methods for combining light output from
color LEDs onto an aperture such as a microdisplay. These
techniques may be readily adapted to embodiments wherein the
microdisplay or spatial light modulator is replaced by the input
surface of coupling lightguides.
Light Collimating Optical Element
[0163] In one embodiment, the light input coupler comprises a light
collimating optical element. A light collimating optical element
receives light from the light source with a first angular
full-width at half maximum intensity within at least one input
plane orthogonal to the input surface and redirects a portion of
the incident light from the light source such that the angular
full-width at half maximum intensity of the light is reduced in the
first input plane. In one embodiment, the light collimating optical
element is one or more of the following: a light source primary
optic, a light source secondary optic, a light input surface, and
an optical element disposed between the light source and at least
one coupling lightguide. In another embodiment, the light
collimating element is one or more of the following: an injection
molded optical lens, a thermoformed optical lens, and a
cross-linked lens made from a mold. In another embodiment, the
light collimating element reduces the angular full-width at half
maximum (FWHM) intensity within a first input plane and a second
plane orthogonal to the first input plane.
Light Turning Optical Element
[0164] In one embodiment, a light input coupler comprises a light
turning optical element disposed to receive light from a light
source with a first optical axis angle and redirect the light to
having a second optical axis angle different than the first optical
axis angle. In one embodiment, the light turning optical element
redirects light by about 90 degrees. In another embodiment, the
light turning optical element redirects the optical axis of the
incident light by an angle selected from within the range of 75
degrees and 90 degrees within at least one plane. In another
embodiment, the light turning optical element redirects the optical
axis of the incident light by an angle selected from within the
range of 40 degrees and 140 degrees. In one embodiment, the light
turning optical element is optically coupled to the light source or
the light input surface of the coupling lightguides. In another
embodiment, the light turning optical element is separated in the
optical path of light from the light source or the light input
surface of the coupling lightguides by an air gap. In another
embodiment, the light turning optical element redirects light from
two or more light sources with first optical axis angles to light
having second optical axis angles different than the first optical
axis angles. In a further embodiment, the light turning optical
element redirects a first portion of light from a light source with
a first optical axis angle to light having a second optical axis
angle different than the first optical axis angle. In another
embodiment, the light turning optical element redirects light from
a first light source with a first optical axis angle to light
having a second optical axis angle different from the first optical
axis angle and light from a second light source with a third
optical axis angle to light having a fourth optical axis angle
different from the third optical axis angle.
Bi-Directional Light Turning Optical Element
[0165] In another embodiment, the light turning optical element
redirects the optical axis of light from one or more light sources
into two different directions. For example, in one embodiment, the
middle coupling lightguide of a light input coupler is a non-folded
coupling lightguide and the light input ends of two arrays of
stacked, folded coupling lightguides are directed toward the middle
coupling lightguide. A bi-directional light turning optical element
is disposed above the middle coupling lightguide such that a first
portion of light from a light source enters the middle coupling
lightguide, a second portion of light from the light source is
directed in a first direction parallel and toward the input surface
of the first stacked array of folded coupling lightguides by the
bi-directional light turning optical element, and a third portion
of light from the light source is directed in a second direction
parallel and toward the input surface of the second stacked array
of folded coupling lightguides by the bi-directional light turning
optical element. In this embodiment, the light source may be
disposed between the lateral edges of the light emitting region or
light emitting device and the non-folded coupling lightguide
eliminates an otherwise dark region (where there is insufficient
room for a folded coupling lightguide) or eliminates the
requirement for multiple bends in the coupling lightguides that can
introduce further light loss and increase volume requirements.
[0166] In one embodiment, the bi-directional light turning optical
element splits and turns the optical axis of one light source into
two different directions. In another embodiment, the bi-directional
light turning optical element rotates the optical axis of a first
light source into a first direction and rotates the optical axis of
a second light source into a second direction different that the
first direction. In another embodiment, an optical element, such as
an injection molded lens, comprises more than one light turning
optical element and light collimating element that are configured
to receive light from more than one light source. For example, an
injection molded lens comprising a linear array of optical light
turning surfaces and light collimating surfaces may be disposed to
receive light from a strip comprising a linear array of LEDs such
that the light is directed into a plurality of light input couplers
or stacks of coupling lightguides. By forming a single optical
element to perform light turning and light collimating for a
plurality of light sources, fewer optical elements are needed and
costs can be reduced, in another embodiment, the bi-directional
light turning element may be optically coupled to the light source,
the coupling lightguides, or a combination thereof.
Light Turning and Light Collimating Optical Element
[0167] In another embodiment, the light turning optical element
turns the optical axis of the light from the light source in a
first plane within the light turning element and collimates the
light in the first plane, in a second plane orthogonal to the first
plane, or a combination thereof. In another embodiment, the light
turning optical element comprises a light turning region and a
collimating region. In one embodiment, by collimating input light
in at least one plane, the light will propagate more efficiently
within the lightguide and have reduced losses in the bend regions
and reduced input coupling losses into the coupling lightguides. In
one embodiment, the light turning optical element is an injection
molded lens designed to redirect light from a first optical axis
angle to a second optical axis angle different from the first
optical axis angle. The injection molded lens may be formed of a
light transmitting material such as poly(methyl methacrylate)
(PMMA), polycarbonate, silicone, or any suitable light transmitting
material. In a further embodiment, the light turning element may be
a substantially planar element that redirects light from a first
optical axis angle to a second optical axis angle in a first plane
while substantially maintaining the optical axis angle in a second
plane orthogonal to the first plane. For example, in one
embodiment, the light turning optical element is a 1 millimeter
(mm) thick lens with a curved profile in one plane cut from a 1 mm
sheet of PMMA using a carbon dioxide (CO.sub.2) laser cutter,
[0168] In one embodiment, the light input coupler comprises a light
turning optical element or coupling lightguides with light turning
edges that permit a light source to be disposed between the
extended bounding regions of the sides of the light emitting
surface adjacent to the input side of the light from the light
source into the lightguide region. In this embodiment, the turning
optical element or light turning edges permit the light source to
be disposed on the light input side region of the lightguide region
without substantially extending beyond either side. Additionally,
in this embodiment, the light source may be folded behind the light
emitting region of the lightguide such that the light source does
not substantially extend beyond an edge of the light emitting
region or outer surface of the light emitting device comprising the
light emitting region. In another embodiment, the light source is
substantially directed with its optical axis oriented toward the
light emitting region and the turning optical element or turning
edges of the coupling lightguides permit the light to be turned
such that it can enter the stacked array of coupling lightguides
that are stacked substantially parallel to the input side of the
lightguide region and substantially orthogonal to the light source
optical axis.
Light Coupling Optical Element
[0169] In one embodiment, a light emitting device comprises a light
coupling optical element disposed to receive light from the light
source and transmit a larger flux of light into the coupling
lightguides than would occur without the light coupling element. In
one embodiment, the light coupling element refracts a first portion
of incident light from a light source such that it is incident upon
the input surface of one or more coupling lightguides or sets of
coupling lightguides at a lower incidence angle from the normal
such that more light flux is coupled into the coupling lightguides
or sets of coupling lightguides (less light is lost due to
reflection). In another embodiment, the light coupling optical
element is optically coupled to at least one selected from the
group: the light source, a plurality of coupling lightguides, a
plurality of sets of coupling lightguides, a plurality of light
sources.
Thermal Stability of Optical Element
[0170] In another embodiment, the light coupling optical element or
light redirecting optical element contains materials with a
volumetric average glass transition temperature higher than the
volumetric average glass transition temperature of the materials
contained within the coupling lightguides. In another embodiment,
the glass transition temperature of the coupling lightguides is
less than 100 degrees Centigrade and the glass transition
temperature of the light coupling optical element or the light
redirecting optical element is greater than 100 degrees Centigrade.
In a further embodiment, the glass transition temperature of the
coupling lightguides is less than 120 degrees Centigrade and the
glass transition temperature of the light coupling optical element
or the light redirecting optical element is greater than 120
degrees Centigrade. In a further embodiment, the glass transition
temperature of the coupling lightguides is less than 140 degrees
Centigrade and the glass transition temperature of the light
coupling optical element or the light redirecting optical element
is greater than 140 degrees Centigrade. In a further embodiment,
the glass transition temperature of the coupling lightguides is
less than 150 degrees Centigrade and the glass transition
temperature of the light coupling optical element or the light
redirecting optical element is greater than 150 degrees Centigrade.
In another embodiment, the light redirecting optical element or the
light coupling optical element comprises polycarbonate and the
coupling lightguides comprise poly(methyl methacrylate). In another
embodiment, at least one of the light redirecting optical element
and the light coupling optical element is thermally coupled to a
thermal transfer element or the housing of the light emitting
device.
Coupling Lightguides
[0171] In one embodiment, the coupling lightguide is a region
wherein light within the region can propagate in a waveguide
condition and a portion of the light input into a surface or region
of the coupling lightguides passes through the coupling lightguide
toward a lightguide or light mixing region. The coupling
lightguide, in some embodiments, may serve to geometrically
transform a portion of the flux from a light source from a first
shaped area to a second shaped area different from the first. In an
example of this embodiment, the light input surface of the light
input coupler formed from the edges of folded strips (coupling
lightguides) of a planar film has the dimensions of a rectangle
that is 3 millimeters by 2.7 millimeters and the light input
coupler couples light into a planar section of a film in the light
mixing region with a cross-sectional dimensions of 40.5 millimeters
by 0.2 millimeters. In one embodiment, the input area of the light
input coupler is substantially the same as the cross-sectional area
of the light mixing region or lightguide disposed to receive light
from one or more coupling lightguides. In another embodiment, the
total transformation ratio, defined as the total light input
surface area of the light input couplers receiving more than 5% of
the light flux from a light source divided by the total
cross-sectional area of the light mixing region or lightguide
region disposed to receive light from the coupling lightguides is
one selected from the group: 1 to 1.1, 0.9 to 1, 0.8 to 0.9, 0.7 to
0.8, 0.6 to 0.7, 0.5 to 0.6, 0.5 to 0.999, 0.6 to 0.999, 0.7 to
0.999, less than 1, greater than 1, equal to 1. In another
embodiment, the input surface area of each light input coupler
corresponding to the edges of coupling lightguides disposed to
receive light from a light source is substantially the same as the
cross-sectional area of the light mixing region or lightguide
region disposed to receive light from each corresponding coupling
lightguides. In another embodiment, the individual transformation
ratio, defined as the total light input area of a single light
input surface of a light input coupler (corresponding to the edges
of coupling lightguides) divided by the total cross-sectional area
of the light mixing region or lightguide disposed to receive light
from the corresponding coupling lightguides is one selected from
the group: 1 to 1.1, 0.9 to 1, 0.8 to 0.9, 0.7 to 0.8, 0.6 to 0.7,
0.5 to 0.6, 0.5 to 0.999, 0.6 to 0.999, 0.7 to 0.999, less than 1,
greater than 1, equal to 1.
[0172] In another embodiment, a coupling lightguide is disposed to
receive light from at least one input surface with a first input
surface longest dimension and transmit the light to a lightguide
with a light emitting surface with a light emitting surface longest
dimension larger than the first input surface largest dimension. In
another embodiment, the coupling lightguide is a plurality of
lightguides disposed to collect light from at least one light
source through edges or surfaces of the coupling lightguides and
direct the light into the surface, edge, or region of a lightguide
comprising a light emitting surface. In one embodiment, the
coupling lightguides provide light channels whereby light flux
entering the coupling lightguides in a first cross sectional area
can be redistributed into a second cross sectional area different
from the first cross sectional area at the light output region of
the light input coupler. The light exiting the light input coupler
or light mixing region may then propagate to a lightguide or
lightguide region which may be a separate region of the same
element (such as a separate region of the same film). In one
embodiment, a light emitting device comprises a light source and a
film processed to form a lightguide region with light extraction
features, a light mixing region wherein light from a plurality of
sources, light input couplers, or coupling lightguides mixes before
entering into the lightguide region. The coupling lightguides,
light mixing region, and light extraction features may all be
formed from, on, or within the same film and they may remain
interconnected to each other through one or more regions.
[0173] In one embodiment, at least one coupling lightguide is
disposed to receive light from a plurality of light sources of at
least two different colors, wherein the light received by the
coupling lightguide is pre-mixed angularly, spatially, or both by
reflecting through the coupling lightguide and the 9-spot sampled
spatial color non-uniformity, .DELTA.u'v', of the light emitting
surface of the light emitting device measured on the 1976 u', v'
Uniform Chromaticity Scale as described in VESA Flat Panel Display
Measurements Standard Version 2.0, Jun. 1, 2001 (Appendix 201, page
249) is less than one selected from the group: 0.2, 0.1, 0.05,
0.01, and 0.004 when measured using a spectrometer based spot color
meter.
Coupling Lightguide Folds and Bends
[0174] In one embodiment, light emitting device comprises a light
mixing region disposed between a lightguide and strips or segments
cut to form coupling lightguides, whereby a collection of edges of
the strips or segments are brought together to form a light input
surface of the light input coupler disposed to receive light from a
light source. In one embodiment, the light input coupler comprises
a coupling lightguide wherein the coupling lightguide comprises at
least one fold or bend in one plane such that at least one edge
overlaps another edge. In another embodiment, the coupling
lightguide comprises a plurality of folds or bends wherein edges of
the coupling lightguide can be abutted together in region such that
the region forms a light input surface of the light input coupler
of the light emitting device.
[0175] In one embodiment, a light emitting device comprises a light
input coupler comprising at least one coupling lightguide that is
bent or folded such that light propagating in a first direction
within the lightguide before the bend or fold is propagating in a
second direction different that the first within the lightguide
after the bend or fold.
[0176] In one embodiment, at least one coupling lightguide
comprises a strip or segment that is bent or folded to radius of
curvature of less than 75 times the thickness of the strip or
segment. In another embodiment, at least one coupling lightguide
comprises a strip or segment that is bended or folded to radius of
curvature greater than 10 times the times the thickness of the
strip or segment. In another embodiment, at least one coupling
lightguide is bent or folded such that longest dimension in a
cross-section through the light emitting device or coupling
lightguide in at least one plane is less than without the fold or
bend. Segments or strips may be bent or folded in more than one
direction or region and the directions of folding or bending may be
different between strips or segments.
Optical Efficiency of the Light Input Coupler
[0177] In an embodiment, the optical efficiency of the light input
coupler, defined as the percentage of the original light flux from
the light source that passes through the light input coupler light
input surface and out of the light input coupler into a mixing
region, lightguide, or light emitting surface, is greater than one
selected from the group: 50%, 60%, 70%, 80%, 90%, and 95%. The
degree of collimation can affect the optical efficiency of the
light input coupler.
Collimation of Light Entering the Coupling Lightguides
[0178] In one embodiment, at least one selected from the group:
light source, light collimating optical element, light source
primary optic, light source secondary optic, light input surface,
optical element disposed between the light source and at least one
selected from the group: coupling lightguide, shape of the coupling
lightguide, shape of the mixing region, shape of the light input
coupler, and shape of an element or region of the light input
coupler provides light incident to the light input surface or
within the coupling lightguide with an angular full-width of half
maximum intensity chosen from the group: less than 80 degrees, less
than 70 degrees, less than 60 degrees, less than 50 degrees, less
than 40 degrees, less than 30 degrees, less than 20 degrees, less
than 10 degrees, between 10 degrees and 30 degrees, between 30
degrees and 50 degrees, between 10 degrees and 60 degrees and
between 30 degrees and 80 degrees within a first plane orthogonal
to the input surface. In some embodiments, light which is highly
collimated (FWHM of about 10 degrees or less) does not mix
spatially within a lightguide region with light extracting features
such that there may be dark bands or regions of non-uniformity. In
this embodiment, the light, however, will be efficiently coupled
around curves and bends in the lightguide relative to less
collimated light and in some embodiments, the high degree of
collimation enables small radii of curvature and thus a smaller
volume for the fold or bend in a light input coupler and resulting
light emitting device. In another embodiment, a significant portion
of light from a light source with a low degree of collimation (FWHM
of about 120 degrees) within the coupling lightguides will be
reflected into angles such that it exits the coupling lightguides
in regions near bends or folds with small radii of curvature. In
this embodiment, the spatial light mixing (providing uniform color
or luminance) of the light from the coupling lightguides in the
lightguide in areas of the light extracting regions is high and the
light extracted from lightguide will appear to have a more uniform
angular or spatial color or luminance uniformity.
[0179] In one embodiment, light from a light source is collimated
in a first plane by a light collimating optical element and the
light is collimated in a second plane orthogonal to the first plane
by light collimating edges of the coupling lightguide. In another
embodiment, a first portion of light from a light source is
collimated by a light collimating element in a first plane and the
first portion of light is further collimated in a second plane
orthogonal to the first plane, the first plane, or a combination
thereof by collimating edges of one or more coupling lightguides.
In a further embodiment, a first portion of light from a light
source is collimated by a light collimating element in a first
plane and a second portion of light from the light source or first
portion of light is collimated in a second plane orthogonal to the
first plane, the first plane, or a combination thereof by
collimating edges of one or more coupling lightguides.
[0180] In another embodiment, one or more coupling lightguides is
bent or folded and the optical axis of the light source is oriented
at a first redirection angle to the light emitting device optical
axis, oriented at a second redirection angle to a second direction
orthogonal to the light emitting device optical axis, and oriented
at a third redirection angle to a third direction orthogonal to the
light emitting device optical axis and the second direction. In
another embodiment, the first redirection angle, second redirection
angle, or third redirection angle is about one selected from the
group: 0 degrees, 45 degrees, 90 degrees, 135 degrees, 180 degrees,
0-90 degrees, 90-180 degrees, and 0-180 degrees.
[0181] Each light source may be oriented at a different angle. For
example, two light sources along one edge of a film with a
strip-type light input coupler can be oriented directly toward each
other (the optical axes are 180 degrees apart). In another example,
the light sources can be disposed in the center of an edge of a
film and oriented away from each other (the optical axes are also
180 degrees apart).
[0182] The segments or strips may be once folded, for example, with
the strips oriented and abutting each other along one side of a
film such that the light source optical axis is in a direction
substantially parallel with the film plane or lightguide plane. The
strips or segments may also be folded twice, for example, such that
the light source optical axis is substantially normal to the film
plane or normal to the waveguide.
[0183] In one embodiment, the fold or bend in the coupling
lightguide, region or segment of the coupling lightguide or the
light input coupler has a crease or radial center of the bend in a
direction that is at a bend angle relative to the light source
optical axis. In another embodiment, the bend angle is one selected
from the group: 0 degrees, 45 degrees, 90 degrees, 135 degrees, 180
degrees, 0-90 degrees, 90-180 degrees, and 0-180 degrees.
[0184] The bend or fold may also be of the single directional bend
(such as vertical type, horizontal type, 45 degree type or other
single angle) or the bend or fold or be multi-directional such as
the twisted type wherein the strip or segment is torsional. In one
embodiment, the strip, segment or region of the coupling lightguide
is simultaneously bent in two directions such that the strip or
segment is twisted.
[0185] In another embodiment, the light input coupler comprises at
least one light source disposed to input light into the edges of
strips (or coupling lightguides) cut into a film wherein the strips
are twisted and aligned with their edges forming an input surface
and the light source output source area is substantially parallel
with the edge of the coupling lightguide, lightguide, lightguide
region, or light input surface or the optical axis of the light
source is substantially perpendicular to the edge of the coupling
lightguide, lightguide, lightguide region, or light input surface.
In another embodiment, multiple light sources are disposed to
couple light into a light input coupler comprising strips cut into
a film such that at least one light source has an optical axis
substantially parallel to the lightguide edge, coupling lightguide
lateral edge or the nearest edge of the lightguide region. In
another embodiment, two groupings of coupling lightguides are
folded separately toward each other such that the separation
between the ends of the strips is substantially the thickness of
the central strip between the two groupings and two or more light
sources are disposed to direct light in substantially opposite
directions into the strips. In one embodiment, two groupings of
coupling lightguides are folded separately toward each other such
and then both folded in a direction away from the film such that
the edges of the coupling lightguides are brought together to form
a single light input surface disposed to receive light from at
least one light source. In this embodiment, the optical axis of the
light source may be substantially normal to the substantially
planar film-based lightguide.
[0186] In one embodiment, two opposing stacks of coupling
lightguides from the same film are folded and recombined at some
point away from the end of the coupling apparatus. This can be
accomplished by splitting the film into one or more sets of two
bundles, which are folded towards each other. In this embodiment,
the bundles can be folded at an additional tight radius and
recombined into a single stack. The stack input can further be
polished to be a flat single input surface or optically coupled to
a flat window and disposed to receive light from a light
source.
[0187] In one embodiment, the combination of the two film stacks is
configured to reduce the overall volume. In one embodiment, the
film is bent or folded to a radius of curvature greater than
10.times. the film thickness order to retain sufficient total
internal reflection for a first portion of the light propagating
within the film.
[0188] In another embodiment, the light input coupler comprises at
least one coupling lightguide wherein the coupling lightguide
comprises an arcuate reflective edge and is folded multiple times
in a fold direction substantially parallel to the lightguide edge
or nearest edge of the lightguide region wherein multiple folds are
used to bring sections of an edge together to form a light input
surface with a smaller dimension. In another embodiment, the light
coupling lightguide, the strips, or segments have collimating
sections cut from the coupling lightguide which directs light
substantially more parallel to the optical axis of the light
source. In one embodiment, the collimating sections of the coupling
lightguide, strips or segments direct light substantially more
parallel to the optical axis of the light source in at least one
plane substantially parallel to the lightguide or lightguide
region.
[0189] In a further embodiment, a light input coupler comprises at
least one coupling lightguide with an arc, segmented arc, or other
light redirect edge cut into a film and the light input coupler
comprises a region of the film rolled up to form a spiral or
concentric-circle-like light input edge disposed to receive light
from a light source.
Coupling Lightguide Lateral Edges
[0190] In one embodiment, the lateral edges, defined herein as the
edges of the coupling lightguide which do not substantially receive
light directly from the light source and are not part of the edges
of the lightguide. The lateral edges of the coupling lightguide
receive light substantially only from light propagating within the
coupling light guide. In one embodiment, the lateral edges are at
least one selected from the group: of uncoated, coated with a
reflecting material, disposed adjacent to a reflecting material,
and cut with a specific cross-sectional profile. The lateral edges
may be coated, bonded to or disposed adjacent to a specularly
reflecting material, partially diffusely reflecting material, or
diffuse reflecting material. In one embodiment, the edges are
coated with a specularly reflecting ink comprising nano-sized or
micron-sized particles or flakes which substantially reflect the
light in a specular manner when the coupling lightguides are
brought together from folding or bending. In another embodiment, a
light reflecting element (such as a multi-layer mirror polymer film
with high reflectivity) is disposed near the lateral edge of at
least one region of a coupling lightguide disposed, the multi-layer
mirror polymer film with high reflectivity is disposed to receive
light from the edge and reflect it and direct it back into the
lightguide. In another embodiment, the lateral edges are rounded
and the percentage of incident tight diffracted out of the
lightguide from the edge is reduced. One method of achieving
rounded edges is by using a laser to cut the strips, segments or
coupling lightguide region from a film and edge rounding through
control of the processing parameters (speed of cut, frequency of
cut, laser power, etc.). Other methods for creating rounded edges
include mechanical sanding/polishing or from chemical/vapor
polishing. In another embodiment, the lateral edges of a region of
a coupling lightguide are tapered, angled serrated, or otherwise
cut or formed such that light from a light source propagating
within the coupling lightguide reflects from the edge such that it
is directed into an angle closer to the optical axis of the light
source, toward a folded or bent region, or toward a lightguide or
lightguide region.
Width of Coupling Lightguides
[0191] In one embodiment, the dimensions of the coupling
lightguides are substantially equal in width and thickness to each
other such that the input surface areas for each edge surface are
substantially the same. In another embodiment, the average width of
the coupling lightguides, w, is determined by the equation:
w=MF*W.sub.LES/NC,
[0192] where W.sub.LES is the total width of the light emitting
surface in the direction parallel to the light entrance edge of the
lightguide region or lightguide receiving light from the coupling
lightguide, NC is the total number of coupling lightguides in the
direction parallel to the light entrance edge of the lightguide
region or lightguide receiving light from the coupling lightguide,
and MF is the magnification factor. In one embodiment, the
magnification factor is one selected from the group: 0.7, 0.8, 0.9,
1, 1.1, 1.2, 1.3, 1.4, 0.7-1.3, 0.8-1.2, and 0.9-1.1. In another
embodiment, at least one selected from the group: coupling
lightguide width, the largest width of a coupling waveguide, the
average width of the coupling lightguides, and the width of each
coupling lightguides is selected from the group: 0.5 mm-1 mm, 1
mm-2 mm, 2 mm-3 mm, 3 mm-4 mm, 5 mm-6 mm, 0.5 mm-2 mm, 0.5 mm-25
mm, 0.5 mm-10 mm, 10-37 mm, and 0.5 mm-5 mm. In one embodiment, at
least one selected from the group: the coupling lightguide width,
the largest width of a coupling waveguide, the average width of the
coupling lightguides, and the width of each coupling lightguides is
less than 20 millimeters.
Shaped or Tapered Coupling Lightguides
[0193] The width of the coupling lightguides may vary in a
predetermined pattern. In one embodiment, the width of the coupling
lightguides varies from a large width in a central coupling
lightguide to smaller width in lightguides further from the central
coupling lightguide as viewed when the light input edges of the
coupling lightguides are disposed together to form a light input
surface on the light input coupler. In this embodiment, a light
source with a substantially circular light output aperture can
couple into the coupling lightguides such that the light at higher
angles from the optical axis are coupled into a smaller width strip
such that the uniformity of the light emitting surface along the
edge of the lightguide or lightguide region and parallel to the
input edge of the lightguide region disposed to receive the light
from the coupling lightguides is greater than one selected from the
group: 60%, 70%, 80%, 90% and 95%.
[0194] Other shapes of stacked coupling lightguides can be
envisioned, such as triangular, square, rectangular, oval, etc.
that provide matched input areas to the light emitting surface of
the light source. The widths of the coupling lightguides may also
be tapered such that they redirect a portion of light received from
the light source. The lightguides may be tapered near the light
source, in the area along the coupling lightguide between the light
source and the lightguide region, near the lightguide region, or
some combination thereof.
[0195] In some embodiments, one light source will not provide
sufficient light flux to enable the desired luminance or light
output profile desired for a particular light emitting device. In
this example, one may use more than one light input coupler and
light source along the edge or side of a lightguide region or
lightguide mixing region. In one embodiment, the average width of
the coupling lightguides for at least one light input coupler are
in a first width range selected from the group: 1-3, 1.01-3,
1.01-4, 0.7-1.5, 0.8-1.5, 0.9-1.5, 1-2, 1.1-2, 1.2-2, 1.3-2, 1.4-2,
0.7-2, 0.5-2, and 0.5-3 times the largest width of the light output
surface of the light source in the direction of the lightguide
coupler width at the light input surface.
[0196] In one embodiment, the coupling lightguide dimensional
ratio, the ratio of the width of the coupling lightguide (the width
is measured as the average dimension orthogonal to the general
direction of propagating within the coupling lightguide toward the
light mixing region, lightguide, or lightguide region) to the
thickness of the coupling lightguide (the thickness is the average
dimension measured in the direction perpendicular to the
propagating plane of the light within the coupling lightguide) is
greater than one selected from the group: 5:1, 10:1, 15:1, 20:1,
25:1, 30:1, 40:1, 50:1, 60:1, 70:1, and 100:1. In one embodiment,
the thickness of the coupling lightguide is less than 600 microns
and the width is greater than 10 millimeters. In one embodiment,
the thickness of the coupling lightguide is less than 400 microns
and the width is greater than 3 millimeters. In a further
embodiment, the thickness of the coupling lightguide is less than
400 microns and the width is greater than 10 millimeters. In
another embodiment, the thickness of the coupling lightguide is
less than 300 microns and the width is less than 10 millimeters. In
another embodiment, the thickness of the coupling lightguide or
light transmitting film is less than 200 microns and the width is
less than 20 millimeters. Imperfections at the lateral edges of the
coupling lightguides (deviations from perfect planar, flat surfaces
due to the cutting of strips, for example) can increase the loss of
light through the edges or surfaces of the coupling lightguides. By
increasing the width of the coupling lightguides, one can reduce
the effects of edge imperfections since the light within the
coupling lightguide bounces (reflects) less off of the lateral edge
surfaces (interacts less with the surface) in a wider coupling
lightguide than a narrow coupling lightguide for a give range of
angles of light propagation. The width of the coupling lightguides
is a factor affecting the spatial color or luminance uniformity of
the light entering the lightguide region, light mixing region, or
lightguide, and when the width of the coupling lightguide is large
compared to the width (in that same direction) of the light
emitting region, then spatially non-uniform regions can occur.
[0197] In another embodiment, the ratio of width of the light
emitting surface area disposed to receive at least 10% of the light
emitted from a grouping of coupling lightguides forming a light
input coupler in a direction parallel to the width of the coupling
lightguides to the average width of the coupling lightguides is
greater than one selected from the group: 5:1, 15:1, 20:1, 25:1,
30:1, 40:1, 50:1, 60:1, 70:1, 100:1, 150:1, 200:1, 300:1, 500:1,
and 1000:1. In another embodiment, the ratio of the total width of
the total light emitting surface disposed to receive the light
emitted from all of the coupling lightguides directing light toward
the light emitting region or surface along the width to the average
coupling lightguide width is greater than one selected from the
group: 5:1, 15:1, 20:1, 25:1, 30:1, 40:1, 50:1, 60:1, 70:1, 100:1,
150:1, 200:1, 300:1, 500:1, and 1000:1.
[0198] In one embodiment, the width of the coupling lightguide is
greater than one of the following: 1.1, 1.2, 1.3, 1.5, 1.8, 2, 3,
4, and 5 times the width of the light output surface of the light
source disposed to couple light into the coupling lightguide. In
another embodiment, the larger coupling lightguide width relative
to the width of the light output surface of the light source allows
for the a higher degree of collimation (lower angular full-width at
half maximum intensity) by the light collimating edges of the
coupling lightguides.
Light Turning Edges of the Coupling Lightguides
[0199] In one embodiment, one or more coupling lightguides have an
edge shape that optically turns by total internal reflection a
portion of light within the coupling lightguide such that the
optical axis of the light within the coupling lightguide is changed
from a first optical axis angle to a second optical axis angle
different than the first optical axis angle. More than one edge of
one or more coupling lightguides may have a shape or profile to
turn the light within the coupling lightguide and the edges may
also provide collimation for portions of the light propagating
within the coupling lightguides. For example, in one embodiment,
one edge of a stack of coupling lightguides is curved such that the
optical axis of the light propagating within the lightguide is
rotated by 90 degrees. In one embodiment, the angle of rotation of
the optical axis by one edge of a coupling lightguide is greater
than one of the following: 10 degrees, 20 degrees, 40 degrees, 45
degrees, 60 degrees, 80 degrees, 90 degrees, and 120 degrees. In
another embodiment, the angle of rotation of the optical axis by
more than one edge region of a coupling lightguide is greater than
one of the following: 10 degrees, 20 degrees, 40 degrees, 45
degrees, 60 degrees, 80 degrees, 90 degrees, 120 degrees, 135
degrees, and 160 degrees. By employing more than one specifically
curved edge, the light may be rotated to a wide range of angles. In
one embodiment, the light within the coupling lightguide is
redirected in a first direction (+theta direction) by a first edge
profile and rotated in a section direction (+theta 2) by a second
edge profile. In another embodiment, the light within the coupling
lightguide is redirected from a first direction to a second
direction by a first edge profile and rotated back toward the first
direction by a second edge profile region further along the
coupling lightguide. In one embodiment, the light turning edges of
the coupling lightguide are disposed in one or more regions
including, without limitation, near the light source, near the
light input surface of the coupling lightguides, near the light
mixing region, near the lightguide region, between the light input
surface of the coupling lightguides, near the light mixing region,
near the region between the coupling lightguides and the lightguide
region, and near the lightguide region.
[0200] In one embodiment, one lateral edge near the light input
surface of the coupling lightguide has a light turning profile and
the opposite lateral edge has a light collimating profile. In
another embodiment, one lateral edge near the light input surface
of the coupling lightguide has a light collimating profile followed
by a light turning profile (in the direction of light propagate
away from the light input surface within the coupling
lightguide).
[0201] In one embodiment, two arrays of stacked coupling
lightguides are disposed to receive light from a light source and
rotate the optical axis of the light into two different directions.
In another embodiment, a plurality of coupling lightguides with
light turning edges may be folded and stacked along an edge of the
lightguide region such that light from a light source oriented
toward the lightguide region enters the stack of folded coupling
lightguides, the light turning edges redirect the optical axis of
the light to a first direction substantially parallel to the edge
and the folds in the stacked coupling lightguides redirect the
light to a direction substantially toward the lightguide region. In
this embodiment, a second array of stacked, folded coupling
lightguides can be stacked above or below (or interleaved with) the
first array of stacked, folded coupling lightguides along the same
edge of the lightguide region such that light from the same light
source oriented toward the lightguide region enters the second
array of stacked, folded coupling lightguides, the light turning
edges of the second array of stack folded coupling lightguides
redirect the optical axis of the light to a second direction
substantially parallel to the edge (and opposite the first
direction) and the folds in the stacked coupling lightguides
redirect the light to a direction substantially toward the
lightguide region, in another embodiment, the coupling lightguides
from two different arrays along an edge of a lightguide region may
be alternately stacked upon each other. The stacking arrangement
may be predetermined, random, or a variation thereof. In another
embodiment, a first stack of folded coupling lightguides from one
side of a non-folded coupling lightguide are disposed adjacent one
surface of the non-folded coupling lightguide and a second stack of
folded coupling lightguides from the other side of the non-folded
coupling lightguide are disposed adjacent the opposite surface of
the non-folded coupling lightguide. In this embodiment, the
non-folded coupling lightguide may be aligned to receive the
central (higher flux) region of the light from the light source
when there are equal numbers of coupling lightguides on the top
surface and the bottom surface of the non-folded coupling
lightguide. In this embodiment, the non-folded coupling lightguide
may have a higher transmission (less light loss) since there are no
folds or bends, thus more light reaches the lightguide region.
[0202] In another embodiment, the light turning edges of one or
more coupling lightguides redirects light from two or more light
sources with first optical axis angles to light having a second
optical axis angles different than the first optical axis angles.
In a further embodiment, the light turning edges of one or more
coupling lightguides redirects a first portion of light from a
light source with a first optical axis angle to a portion of light
having second optical axis angle different than the first optical
axis angle. In another embodiment, the light turning edges of one
or more coupling lightguides redirects light from a first light
source with a first optical axis angle to light having a second
optical axis angle different from the first optical axis angle and
light from a second light source with a third optical axis angle to
light having a fourth optical axis angle different from the third
optical axis angle.
[0203] In one embodiment, the light turning profile of one or more
edges of a coupling lightguide has a curved shape when viewed
substantially perpendicular to the film. In another embodiment, the
curved shape has one or more conic, circular arc, parabolic,
hyperbolic, geometric, parametric, or other algebraic curve
regions. In another embodiment, the shape of the curve is designed
to provide improved transmission through the coupling lightguide by
minimizing bend loss (increased reflection) for a particular light
input profile to the coupling lightguide, light input surface,
light profile modifications before the curve (such as collimating
edges for example), refractive indexes for the wavelengths of
interest for the coupling lightguide material, surface finish of
the edge, and coating or cladding type at the curve edge (low
refractive index material, air, or metallized for example). In one
embodiment, the light lost from the light turning profile of one or
more edge regions of the coupling lightguide is less than one of
the following: 50%, 40%, 30%, 20%, 10%, and 5%.
Vertical Light Turning Edges
[0204] In one embodiment, the vertical edges of the coupling
lightguides (the edges tangential to the larger film surface) or
the core regions of the coupling lightguides have a
non-perpendicular cross-sectional profile that rotates the optical
axis of a portion of incident light. In one embodiment, the
vertical edges of one or more coupling lightguides or core regions
of the coupling lightguides comprise a curved edge. In another
embodiment, the vertical edges of one or more coupling lightguides
or core regions comprise an angled edge wherein the angle to the
surface normal of the coupling lightguide is greater than one of
the following: 10 degrees, 20 degrees, 30 degrees, 40 degrees, 50
degrees and 60 degrees. In one embodiment, the use of vertical
light turning edges of the core regions or coupling lightguides
allows light to enter into the coupling lightguides from the
coupling lightguide film surface where it is typically easier to
obtain an optical finish as it can be the optically smooth surface
of a film. In another embodiment, the coupling lightguides (or core
regions of the coupling lightguides) are brought in contact and the
vertical edges are cut at an angle to the surface normal. In one
embodiment, the angled cut creates a smooth, continuous, angled
vertical light turning edge on the edges of the coupling
lightguides. In another embodiment, the angled, curved, or
combination thereof vertical light turning edges are obtained by
one or more of the following: laser cutting, polishing, grinding,
die cutting, blade cutting or slicing, and hot blade cutting or
slicing. In one embodiment, the vertical light turning edges are
formed when the coupling lightguides are cut into the lightguide
film and the coupling lightguides are aligned to form a vertical
light turning edge.
[0205] In another embodiment, the light input surface of the
coupling lightguides is the surface of one or more coupling
lightguides and the surface comprises one or more surface relief
profiles (such as an embossed Fresnel lens, microlens array, or
prismatic structures) that turns, collimates or redirects a portion
of the light from the light source. In a further embodiment, a
light collimating element, light turning optical element, or light
coupling optical element is disposed between the light source and
the light input film surface of the coupling lightguide (non-edge
surface). In one embodiment, the light input film surface is the
surface of the cladding region or the core region of the coupling
lightguide. In a further embodiment, the light collimating optical
element, light turning optical element, or light coupling optical
element is optically coupled to the core region, cladding region,
or intermediate light transmitting region between the optical
element and the coupling lightguide.
Vertical Light Collimating Edges
[0206] In one embodiment, the vertical edges of the coupling
lightguide (the edges tangential to the larger film surface) or the
core regions of the coupling lightguides have a non-perpendicular
cross-sectional profile that collimate a portion of incident light.
In one embodiment, the vertical edges of one or more coupling
lightguides or core regions of the coupling lightguides comprise a
curved edge that collimates a portion of incident light. In another
embodiment, the vertical edges of one or more coupling lightguides
or core regions comprise an angled edge wherein the angle to the
surface normal of the coupling lightguide is greater than one of
the following: 10 degrees, 20 degrees, 30 degrees, 40 degrees, 50
degrees and 60 degrees.
Non-Folded Coupling Lightguide
[0207] In a further embodiment, the film-based lightguide comprises
a non-folded coupling lightguide disposed to receive light from the
light input surface and direct light toward the lightguide region
without turning the light. In one embodiment, the non-folded
lightguide is used in conjunction with one or more light turning
optical elements, light coupling optical elements, coupling
lightguides with light turning edges, or coupling lightguides with
collimating edges. For example, a light turning optical element may
be disposed above or below a non-folded coupling lightguide such
that a first portion of light from a light source substantially
maintains the direction of its optical axis while passing through
the non-folded coupling lightguide and the light from the source
received by the light turning optical element is turned to enter
into a stacked array of coupling lightguides. In another
embodiment, the stacked array of coupling lightguides comprises
folded coupling lightguides and a non-folded coupling
lightguide.
[0208] In another embodiment, the non-folded coupling lightguide is
disposed near an edge of the lightguide. In one embodiment, the
non-folded coupling lightguide is disposed in the middle region of
the edge of the lightguide region. In a further embodiment, the
non-folded coupling lightguide is disposed along a side of the
lightguide region at a region between the lateral sides of the
lightguide region. In one embodiment, the non-folded coupling
lightguide is disposed at various regions along one edge of a
lightguide region wherein a plurality of light input couplers are
used to direct light into the side of a lightguide region.
[0209] In another embodiment, the folded coupling lightguides have
light collimating edges, substantially linear edges, or light
turning edges. In one embodiment, at least one selected from the
group: the array of folded coupling lightguides, light turning
optical element, light collimating optical element, and light
source are physically coupled to the non-folded coupling
lightguide. In another embodiment, folded coupling lightguides are
physically coupled to each other and to the non-folded coupling
lightguide by a pressure sensitive adhesive cladding layer and the
thickness of the unconstrained lightguide film comprising the light
emitting region and the array of coupling lightguides is less than
one of the following: 1.2 times, 1.5 times, 2 times, and 3 times
the thickness of the array of coupling lightguides. By bonding the
folded coupling lightguides only to themselves, the coupling
lightguides (when un-constrained) typically bend upward and
increase the thickness of the array due to the folded coupling
lightguides not being physically coupled to a fixed or relatively
constrained region. By physically coupling the folded coupling
lightguides to a non-folded coupling lightguide, the array of
coupling lightguides is physically coupled to a separate region of
the film which increases the stability and thus reduces the ability
of the elastic energy stored from the bend to be released.
[0210] In one embodiment, the non-folded coupling lightguide
comprises one or more of the following: light collimating edges,
light turning edges, angled linear edges, and curved light
redirecting edges. The non-folded coupling lightguide or the folded
coupling lightguides may comprise curved regions near bend regions,
turning regions, or collimating regions such that stress (such as
resulting from torsional or lateral bending) does not focus at a
sharp corner and increase the likelihood of fracture. In another
embodiment, curved regions are disposed where the coupling
lightguides join with the lightguide region or light mixing region
of the film-based lightguide.
[0211] In another embodiment, at least one selected from the group:
non-folded coupling lightguide, folding coupling lightguide, light
collimating element, light turning optical element, light
redirecting optical element, light coupling optical element, light
mixing region, lightguide region, and cladding region of one or
more elements is physically coupled to the relative position
maintaining element. By physically coupling the coupling
lightguides directly or indirectly to the relative position
maintaining element, the elastic energy stored from the bend in the
coupling lightguides held within the coupling lightguides and the
combined thickness of the unconstrained coupling lightguides
(unconstrained by an external housing for example) is reduced.
Interior Light Directing Edge
[0212] In one embodiment, the interior region of one or more
coupling lightguides comprises an interior light directing edge.
The interior light redirecting edge may be formed by cutting or
otherwise removing an interior region of the coupling lightguide.
In one embodiment, the interior light directed edge redirects a
first portion of light within the coupling lightguide. In one
embodiment, the interior light redirecting edges provide an
additional level of control for directing the light within the
coupling lightguides and can provide light flux redistribution
within the coupling lightguide and within the lightguide region to
achieve a predetermined light output pattern (such as higher
uniformity or higher flux output in a specific region).
Cavity Region within the Coupling Lightguides
[0213] In one embodiment, one or more coupling lightguides or core
regions of coupling lightguides comprises at least one cavity. In
another embodiment, the cavity is disposed to receive the light
source and the vertical edges of the core regions of the coupling
lightguides are vertical light collimating optical edges. In one
embodiment, a higher flux of light is coupled within the coupling
lightguides with a cavity in at least one coupling lightguide than
is coupled into the coupling lightguides without the cavity. This
may be evaluated, for example, by measuring the light flux out of
the coupling lightguides (when cut) or out of the light emitting
device with an integrating sphere before and after filling the
cavity with a high transmittance (>90% transmittance) light
transmitting material (with the light source disposed adjacent the
corresponding surface of the material) that is index-matched with
the core region. In another embodiment, the cavity region provides
registration or alignment of the coupling lightguides with the
light source and increased light flux coupling into the coupling
lightguides. In one embodiment, an array of coupling lightguides
with vertical light collimating edges and a cavity alleviates the
need for a light collimating optical element.
Coupling Lightguides Comprising Coupling Lightguides
[0214] In one embodiment, at least one coupling lightguide
comprises a plurality of coupling lightguides. For example, a
coupling lightguide may be further cut to comprise a plurality of
coupling lightguides that connect to the edge of the coupling
lightguide. In one embodiment, a film of thickness T comprises a
first array of N number of coupling lightguides, each comprising a
sub-array of M number of coupling lightguides. In this embodiment,
the first array of coupling lightguides is folded in a first
direction such that the coupling lightguides are aligned and
stacked, and the sub-array of coupling lightguides is folded in a
second direction such that the coupling lightguides are aligned and
stacked. In this embodiment, the light input edge surface
comprising the sub-array of coupling lightguides has a width the
same as each of the more narrow coupling lightguides and the light
input surface has a height, H, defined by H=T.times.N.times.M. This
can, for example, allow for the use of a thinner lightguide film to
be used with a light source with a much larger dimension of the
light output surface. In one embodiment, thin film-based
lightguides are utilized, for example, when the film-based
lightguide is the illuminating element of a frontlight disposed
above a touchscreen in a reflective display. A thin lightguide in
this embodiment provides a more accurate, and responsive
touchscreen (such as with capacitive touchscreens for example) when
the user touches the lightguide film. Alternatively, a light source
with a larger dimension of the light output surface may be used for
a specific lightguide film thickness.
[0215] Another advantage of using coupling lightguides comprising a
plurality of coupling lightguides is that the light source can be
disposed within the region between the side edges of the lightguide
region and thus not extend beyond an edge of the display or light
emitting region when the light source and light input coupler are
folded behind the light emitting surface, for example.
Number of Coupling Lightguides in a Light Input Coupler
[0216] In one embodiment, the total number of coupling lightguides,
NC, in a direction parallel to the light entrance edge of the
lightguide region or lightguide receiving light from the coupling
lightguide is NC=MF*W.sub.LES/w, where W.sub.LES is the total width
of the light emitting surface in the direction parallel to the
light entrance edge of the lightguide region or lightguide
receiving light from the coupling lightguide, w is the average
width of the coupling lightguides, and MF is the magnification
factor. In one embodiment, the magnification factor is one selected
from the group: 0.7, 0.8, 0.9, 1, 1.1, 1.2, 1.3, 1.4, 0.7-1.3,
0.8-1.2, and 0.9-1.1. In another embodiment, the number of coupling
lightguides in a light input coupler or the total number of
coupling lightguides in the light emitting device is selected from
the group: 2, 3, 4, 5, 6, 8, 10, 11, 20, 30, 50, 70, 80, 90, 100,
2-50, 3-50, 4-50, 2-500, 4-500, greater than 10, greater than 20,
greater than 30, greater than 40, greater than 50, greater than 60,
greater than 70, greater than 80, greater than 90, greater than
100, greater than 120, greater than 140, greater than 200, greater
than 300, greater than 400, greater than 500.
Coupling Lightguides Directed into More than One Light Input
Surface
[0217] In a further embodiment, the coupling lightguides
collectively do not couple light into the light mixing region,
lightguide, or light mixing region in a contiguous manner. For
example, every other coupling lightguide may be cut out from the
film-based lightguide while still providing strips or coupling
lightguides along one or more edges, but not continuously coupling
light into the lightguide regions. By using fewer lightguides, the
collection of light input edges may be reduced in size. This
reduction in size, for example, can be used to combine multiple
sets of coupling lightguides optically coupled to different regions
of the same lightguide or a different lightguide, better match the
light input surface size to the light source size, use a smaller
light source, or use a thicker lightguide film with a particular
light source where the dimension of the set of contiguous coupling
lightguides in the thickness direction would be one selected from
the group: 10%, 20%, 40%, 50%, and 100% greater than light emitting
surface of the light source in the thickness direction when
disposed to couple light into the light input surface.
[0218] In a further embodiment, coupling lightguides from a first
region of a lightguide have light input edges collected into two or
more light input surfaces. For example, the odd number coupling
lightguides may be directed to a first white light source and the
even number coupling lightguides may be coupled to a red, green,
and blue light source. In another embodiment, the coupling
lightguides from a first region of a lightguide are coupled to a
plurality of white light sources to reduce visibility of color
variations from the light source. For example, the even number
coupling lightguides may couple light from a white light source
with a first color temperature and the odd number coupling
lightguides may couple light from a white light source with a
second color temperature higher than the first such that the color
non-uniformity, .DELTA.u'v', along a direction parallel to an edge
of the lightguide region along the light emitting surface is less
than one selected from the group: 0.2, 0.1, 0.05, 0.01, and
0.004.
[0219] Similarly, three or more light input surfaces may also be
used to couple light from 1, 2, 3 or more light sources. For
example, every alternating first, second, and third coupling
lightguide from a first region of a lightguide are directed to a
first, second, and third light source of the same or different
colors.
[0220] In a further embodiment, coupling lightguides from a first
region of a lightguide have light input edges collected into two or
more light input surfaces disposed to couple light into the
lightguide for different modes of operation. For example, the first
light input surface may be coupled to at least one light source
suitable for daylight compatible output and the second light input
surface may be coupled to at least one light source for NVIS
compatible light output.
[0221] The order of the coupling lightguides directed to more than
one light input surface do not need to be alternating and may be of
any predetermined or random configuration. For example, the
coupling lightguides from the top and bottom region of the
lightguide may be directed to a different light input surface than
the middle region. In a further embodiment, the coupling
lightguides from a region of the lightguide are disposed together
into a plurality of light input surfaces, each comprising more than
one light input edge, arranged in an array, disposed to couple
light from a collection of light sources, disposed within the same
housing, disposed such that the light input surfaces are disposed
adjacent each other, disposed in an order transposed to receive
light from a collection of light sources, disposed in a
non-contiguous arrangement wherein neighboring light input surfaces
do not couple light into neighboring regions of the lightguide,
lightguide region, or light mixing region.
[0222] In a further embodiment, a plurality of sets of coupling
lightguides are arranged to provide a plurality of sets of light
input surface along the same side, edge, the back, the front or
within the same housing region of the light emitting device wherein
the plurality of light input surfaces are disposed to receive light
from one or a plurality of LEDs.
Order of Coupling Lightguides
[0223] In one embodiment, the coupling lightguides are disposed
together at a light input edge forming a light input surface such
that the order of the strips in a first direction is the order of
the coupling lightguides as they direct light into the lightguide
or lightguide region. In another embodiment, the coupling
lightguides are interleaved such that the order of the strips in a
first direction is not the same as the order of the coupling
lightguides as they direct light into the lightguide or lightguide
region. In one embodiment, the coupling lightguides are interleaved
such that at least one coupling lightguide receiving light from a
first light source of a first color is disposed between two
coupling lightguides at a region near the lightguide region or
light mixing region that receive light from a second light source
with a second color different from the color of the first light
source. In one embodiment, the color non-uniformity, .DELTA.u'v',
along a direction parallel to the edge of the lightguide region
along the light emitting surface is less than one selected from the
group: 0.2, 0.1, 0.05, 0.01, and 0.004. In another embodiment, the
coupling lightguides are interleaved such that at least one pair of
coupling lightguides adjacent to each other at the output region of
the light input coupler near the light mixing region, lightguide,
or lightguide region, are not adjacent to each other near the input
surface of the light input coupler. In one embodiment, the
interleaved coupling lightguides are arranged such that the
non-uniform angular output profile is made more uniform at the
output of the light input coupler by distributing the coupling
lightguides such that output from the light input coupler does not
spatially replicate the angular non-uniformity of the light source.
For example, the strips of a light input coupler could alternate
among four different regions of the lightguide region as they are
combined at the light input surface so that the middle region would
not have very high luminance light emitting surface region that
corresponds to the typically high intensity from a light source at
0 degrees or along its optical axis.
[0224] In another embodiment, the coupling lightguides are
interleaved such that at least one pair of coupling lightguides
adjacent to each other near the light mixing region, lightguide, or
lightguide region, do not receive light from at least one of the
same light source, the same light input coupler, and the same
mixing region. In another embodiment, the coupling lightguides are
interleaved such that at least one pair of coupling lightguides
adjacent to each other near a light input surface do not couple
light to at least one of the same light input coupler, the same
light mixing region, the same lightguide, the same lightguide
region, the same film, the same light output surface. In another
embodiment, the coupling lightguides are interleaved at the light
input surface in a two-dimensional arrangement such that at least
two neighboring coupling lightguides in a vertical, horizontal or
other direction at the input surface do not couple light to a
neighboring region of at least one selected from the group: the
same light input coupler, the same light mixing region, the same
lightguide, the same lightguide region, the same film, and the same
light output surface.
[0225] In a further embodiment, coupling lightguides optically
coupled to the lightguide region, light mixing region, or light
emitting region near a first input region are arranged together in
a holder disposed substantially along or near a second edge region
which is disposed along an edge direction greater than one selected
from the group: 30 degrees, 40 degrees, 50 degrees, 60 degrees, 70
degrees, 80 degrees and 85 degrees to first edge region. For
example, light input couplers may couple light from a first light
source and coupling lightguide holder disposed along the bottom
edge of a liquid crystal display and direct the light into the
region of the lightguide disposed along a side of the display
oriented about 90 degrees to the bottom edge of the display. The
coupling lightguides may direct light from a light source disposed
along the top, bottom, or both into one or more sides of a display
such that the light is substantially propagating parallel to the
bottom and top edges within the lightguide region.
Coupling Lightguides Bonded to the Surface of a Lightguide
Region
[0226] In one embodiment, the coupling lightguides are not
segmented (or cut) regions of the same film which comprises the
lightguide or lightguide region. In one embodiment, the coupling
lightguides are formed and physically or optically attached to the
lightguide, light mixing region, or lightguide region using at
least one selected from the group: optical adhesive, bonding method
(solvent welding, thermally bonding, ultrasonic welding, laser
welding, hot gas welding, freehand welding, speed tip welding,
extrusion welding, contact welding, hot plate welding, high
frequency welding, injection welding, friction welding, spin
welding, welding rod), and adhesive or joining techniques suitable
for polymers. In one embodiment, the coupling lightguides are
formed and optically coupled to the lightguide, mixing region, or
lightguide region such that a significant portion of the light from
the coupling lightguides is transferred into a waveguide condition
within the mixing region, lightguide region, or lightguide. The
coupling lightguide may be attached to the edge or a surface of the
light mixing region, lightguide region, or lightguide. In one
embodiment, the coupling lightguides are disposed within a first
film wherein a second film comprising a lightguide region is
extruded onto a region of the first film such that the coupling
lightguides are optically coupled to the lightguide region. In
another embodiment, the coupling lightguides are tapered in a
region optically coupled to the lightguide. By separating out the
production of the coupling lightguides with the production of the
lightguide region, materials with different properties may be used
for each region such as materials with different optical
transmission properties, flexural modulus of elasticity, impact
strength (Notched Izod), flexural rigidity, impact resistance,
mechanical properties, physical properties, and other optical
properties. In one embodiment, the coupling lightguides comprise a
material with a flexural modulus less than 2 gigapascals and the
lightguide or lightguide region comprises a material with a
flexural modulus greater than 2 gigapascals measured according to
ASTM D790. In one embodiment, the lightguide is a relatively stiff
polycarbonate material and the coupling lightguides comprise a
flexible elastomer or polyethylene. In another embodiment, the
lightguide is an acrylic material and the coupling lightguides
comprise a flexible fluoropolymer, elastomer or polyethylene. In
one embodiment, the average thickness of the lightguide region or
lightguide is more than 0.1 mm thicker than the average thickness
of at least one coupling lightguide.
[0227] In one embodiment, at least one coupling lightguide is
optically coupled to at least one selected from the group: surface,
edge, or interior region, of an input light coupler, light mixing
region, lightguide region, and lightguide. In another embodiment, a
film comprising parallel linear cuts along the a direction of a
film is bonded to a surface of a film in the extrusion process such
that the strips are optically coupled to the lightguide film and
the cut regions can be cut in the transverse direction to "free"
the strips so that they can be brought together to form a light
input surface of a light input coupler.
Coupling Lightguides Ending within the Lightguide Region
[0228] In one embodiment, a film comprising parallel linear cuts
along the machine direction of a film is guided between two
extrusion layers or coatings such that the ends of the strips are
effectively inside the other two layers or regions. In another
embodiment, one or more edges of the coupling lightguide are
optically couple to a layer or coating (such as an adhesive) within
a lightguide to reduce scattering and increase light coupling into
the lightguide. This could be done in a single step or in
sequential steps. By having strips or coupling lightguides
terminate within a lightguide, lightguide region, or light mixing
region, there are fewer back reflections from the air-end edge
interface as there would be on a simple surface bonding because the
edge would effectively be optically coupled into the volume of the
light transmitting material forming the light mixing region,
lightguide region or lightguide (assuming the material near the
edge could flow or deform around the edge or another material is
used (such as an adhesive) to promote the optical coupling of the
edge and potentially surfaces.
Strip or Coupling Lightguide Registration Securing Feature
[0229] In one embodiment, at least one strip near the central
region of a light input coupler is used to align or guide the
coupling strips or to connect the coupling lightguides to a
lightguide or housing. In a fold-design wherein the coupling
lightguides are folded toward the center of the light input
coupler, a central strip or lightguide may not be folded to receive
light from the light source due to geometrical limitations on the
inability to fold the central strip or coupling lightguide. This
central strip or coupling lightguide may be used for one selected
from the group: aligning the light input coupler or housing to the
strips (or lightguide), tightening the fold of the strips or
coupling lightguide stack to reduce the volume, registering,
securing or locking down the position of the light input coupler
housing, provide a lever or arm to pull together components of a
folding mechanism which bend or fold the coupling lightguides,
coupling lightguides, lightguide or other element relative to one
of the aforementioned elements.
Tab Region
[0230] In one embodiment, one or more of the strips or coupling
lightguides comprises a tab or tab region that is used to register,
align, or secure the location of the strip or coupling lightguide
relative to the housing, folder, holder, lightguide, light source,
light input coupler, or other element of the light emitting device.
In another embodiment, at least one strip or coupling lightguide
comprises a pin, hole, cut-out, tab, or other feature useful for
registering, aligning, or securing the location of the strip or
coupling lightguide. In one embodiment, the tab region is disposed
at a side of one or more light sources when the light source is
disposed to couple light into a coupling lightguide. In a further
embodiment, the tab region may be removed, by tearing for example,
after the stacking of the coupling lightguides. For example, the
coupling lightguides may have an opening or aperture cut within the
coupling lightguides that align to form a cavity within which the
light emitting region of the light source may be disposed such that
the light from the light source is directed into the light input
surfaces of the coupling lightguides. After physically constraining
the coupling lightguides (by adhering them to each other or to
another element or by mechanical clamping, alignment guide or other
means for example), all or a portion of the tab region may be
removed by tearing without reducing the optical quality of the
light input surface disposed to receive light from the light
source. In another embodiment, the tab region comprises one or more
perforations or cut regions that promote the tearing or removal of
the tab region along a predetermined path.
[0231] In another embodiment, the tab region or region of the
coupling lightguides comprising registration or alignment openings
or apertures are stacked such that the openings or apertures align
onto a registration pin or post disposed on or physically coupled
to the light turning optical element, light collimating optical
element, light coupling element, light source, light source circuit
board, relative position maintaining element, light input coupler
housing, or other element of the light input coupler such that the
light input surfaces of the coupling lightguides are aligned and
disposed to receive light from the element or light source.
[0232] The tab region may comprise registration openings or
apertures on either side of the openings or apertures forming the
cavity in coupling lightguide such that registration pins assist in
the aligning and relative positioning of the coupling lightguides.
In another embodiment, one or more coupling lightguides (folded
non-folded) comprise low light loss registration openings or
apertures in a low light flux region. Low light loss registration
openings or apertures in low light flux regions of the coupling
lightguides are those wherein less than one of the following: 2%,
5%, 10% and 20% of the light flux from a light source reaches the
opening or aperture directly or indirectly within a coupling
lightguide. This can be measured by filling the openings or
apertures with a black light absorbing material such as a black
latex paint and measuring the loss in light output from the light
emitting region using an integrating sphere.
[0233] In another embodiment, the tab regions of the coupling
lightguides allow for the light input surface of the stacked array
of coupling lightguides to be formed after stacking the coupling
lightguides such that an improved optical finish of the light input
surface can be obtained. For example, in one embodiment, the array
of coupling lightguides is stacked with a tab region extended from
the input region of the coupling lightguides. The stacked array is
then cut in the tab region (and optionally mechanically, thermally,
chemically or otherwise polished) to provide a continuous smooth
input surface.
Holding the Coupling Lightguide Position Relative to the Light
Source or Optical Element
[0234] In another embodiment, the tab region may be cut to provide
a physically constraining mechanism for an optical element or the
light source. For example, in one embodiment, the tab region of the
coupling lightguides comprises one or more arms or ridges such that
when the coupling lightguides are stacked in an array, the arms or
ridges form a constraining groove or cavity to substantially
maintain the optical element or light source in at least one
direction. In another embodiment, the stacked array of coupling
lightguides form a cavity that allows an extended ridge of a light
collimating optic to be positioned within the cavity such that the
light collimating optic substantially maintains its position
relative to the coupling lightguides. Various forms of grooves,
ridges, interlocking shapes, pins, openings, apertures and other
constraining shapes may be used with the optical element (such as
the light turning optical element or light collimating optical
element) or the light source (or housing of the light source) and
the shape cut into the coupling lightguides to constrain the
element or light source when placed into the interlocking
shape.
Extended Coupling Lightguides
[0235] In one embodiment, the coupling lightguides are extended
such that the coupling lightguides may be folded in an organized
fashion by using a relative position maintaining element. By
extending the coupling lightguides, the relative position and order
of the coupling lightguides may be maintained during the aligning
and stacking process such that the coupling lightguides may be
stacked and aligned in an organized fashion. For example, in one
embodiment, the coupling lightguides are extended with an inverted
shape such that they are mirrored along a first direction. In one
embodiment, the folding operation creates two stacked arrays of
coupling lightguides which may be used to form two different light
emitting devices or two illuminated regions illuminated by the same
light source. In another embodiment, a first relative position
maintaining element substantially maintains the relative position
of the coupling lightguides near a first lightguide region and a
second relative position maintaining element substantially
maintains the relative position of the extended regions of the
coupling lightguides (which may form the coupling lightguides of a
second light emitting device or region).
Varying Coupling Lightguide Thickness
[0236] In one embodiment, at least one coupling lightguide or strip
varies in the thickness direction along the path of the light
propagating through the lightguide. In one embodiment, at least one
coupling lightguide or strip varies in the thickness direction
substantially perpendicular to the path of the light propagating
through the lightguide. In another embodiment, the dimension of at
least one coupling lightguide or strip varies in a direction
parallel to the optical axis of the light emitting device along the
path of the light propagating through the lightguide. In one
embodiment, the thickness of the coupling lightguide increases as
the light propagates from a light source to the light mixing
region, lightguide, or lightguide region. In one embodiment, the
thickness of the coupling lightguide decreases as the light
propagates from a light source to the light mixing region,
lightguide, or lightguide region. In one embodiment, the thickness
of a coupling lightguide in a first region divided by the thickness
of the coupling lightguide in a second region is greater than one
selected from the group: 1, 2, 4, 6, 10, 20, 40, 60 and 100.
Light Turning Optical Elements or Edges for Light Source
Placement
[0237] In one embodiment, the light turning optical elements or
light turning coupling lightguide edges may be used to position the
light source on the same side of the lightguide region as the
coupling lightguides. In another embodiment, the light turning
optical elements or light turning coupling lightguide edges may be
used to position the light source within the extended boundaries of
the coupling lightguides such that the light source does not extend
past an edge of the lightguide, light emitting region, edges of the
display area, lightguide region or bevel. For example, a film-based
lightguide with coupling lightguides folded along one edge may have
angled edges or a region of the lightguide region not to be
directly illuminated from a coupling lightguide in order to
position the light source within the region bounded by the edges of
the lightguide region. Alternatively, the stack of coupling
lightguides along one edge may have light turning edges near the
light source ends such that the light source can be disposed with
light directed toward the lightguide region. This can allow the
light to be turned and directed into the coupling lightguides and
when the light source is folded behind the display, the light
source does not extend past the outer display edges.
Light Mixing Region
[0238] In one embodiment, a light emitting device comprises a light
mixing region disposed in an optical path between the light input
coupler and the lightguide region. The light mixing region can
provide a region for the light output from individual coupling
lightguides to mix together and improve at least one of the spatial
luminance uniformity, spatial color uniformity, angular color
uniformity, angular luminance uniformity, angular luminous
intensity uniformity or any combination thereof within a region of
the lightguide or of the surface or output of the light emitting
region or light emitting device. In one embodiment, the width of
the light mixing region is selected from a range from 0.1 mm (for
small displays) to more than 3.048 meters (for large billboards).
In one embodiment, the light mixing region is the region disposed
along an optical path near the end region of the coupling
lightguides whereupon light from two or more coupling lightguides
may inter-mix and subsequently propagate to a light emitting region
of the lightguide. In one embodiment, the light mixing region is
formed from the same component or material as at least one of the
lightguide, lightguide region, light input coupler, and coupling
lightguides. In another embodiment, the light mixing region
comprises a material that is different than at least one selected
from the group: the lightguide, lightguide region, light input
coupler, and coupling lightguides. The light mixing region may be a
rectangular, square or other shaped region or it may be a
peripheral region surrounding all or a portion of the light
emitting region or lightguide region. In one embodiment, the
surface area of the light mixing region of a light emitting device
is one selected from the group: less than 1%, less than 5%, less
than 10%, less than 20%, less than 30%, less than 40%, less than
50%, less than 60%, less than 70%, greater than 20%, greater than
30%, greater than 40% greater than 50%, greater than 60%, greater
than 70%, greater than 80%, greater than 90%, 1-10%, 10-20%,
20-50%, 50-70%, 70-90%, 80-95% of the total outer surface area of
the light emitting surface or the area of the light emitting
surface from which light is emitted.
[0239] In one embodiment, a film-based lightguide comprises a light
mixing region with a lateral dimension longer than a coupling
lightguide width and the coupling lightguides do not extend from
the entire edge region corresponding to the light emitting region
of the lightguide. In one embodiment, the width of the gap along
the edge without a coupling lightguide is greater than one of the
following: 1 times, 2 times, 3 times, or 4 times the average width
of the neighboring coupling lightguides. In a further embodiment,
the width of the gap along the edge without a coupling lightguide
is greater than one of the following: 1 times, 2 times, 3 times, or
4 times the lateral width of the light mixing region. For example,
in one embodiment, a film-based lightguide comprises coupling
lightguides with a width of 2 centimeters disposed along a light
mixing region that is 4 centimeters long in the lateral direction
(such as can readily be the case if the light mixing region folds
behind a reflective display for a film-based frontlight), except in
a central region where there is a 2 centimeter gap without a
coupling lightguide extension. In this embodiment, the light within
the neighboring coupling lightguides may spread into the gap region
of the light mixing region not illuminated by a coupling lightguide
directly and mix together such that the light in the light emitting
area is sufficiently uniform. In a further embodiment, a light
mixing region comprises two or more gaps without coupling
lightguides extending therefrom. In a further embodiment, a light
mixing region comprises alternating gaps between the coupling
lightguide extensions along an edge of a film-based lightguide.
Cladding Layer
[0240] In one embodiment, at least one of the light input coupler,
coupling lightguide, light mixing region, lightguide region, and
lightguide comprises a cladding layer optically coupled to at least
one surface. A cladding region, as used herein, is a layer
optically coupled to a surface wherein the cladding layer comprises
a material with a refractive index, n.sub.ciad, less than the
refractive index of the material, n.sub.m, of the surface to which
it is optically coupled. In one embodiment, n.sub.m-n.sub.clad is
one selected from the group: 0.001-0.005, 0.001-0.01, 0.001-0.1,
0.001-0.2, 0.001-0.3, 0.001-0.4, 0.01-0.1, 0.1-0.5, 0.1-0.3,
0.2-0.5, greater than 0.01, greater than 0.1, greater than 0.2, and
greater than 0.3. In one embodiment, the cladding is one selected
from the group: methyl based silicone pressure sensitive adhesive,
fluoropolymer material (applied with using coating comprising a
fluoropolymer substantially dissolved in a solvent), and a
fluoropolymer film. The cladding layer may be incorporated to
provide a separation layer between the core or core part of a
lightguide region and the outer surface to reduce undesirable
out-coupling (for example, frustrated totally internally reflected
light by touching the film with an oily finger) from the core or
core region of a lightguide. Components or objects such as
additional films, layers, objects, fingers, dust etc. that come in
contact or optical contact directly with a core or core region of a
lightguide may couple light out of the lightguide, absorb light or
transfer the totally internally reflected light into a new layer.
By adding a cladding layer with a lower refractive index than the
core, a portion of the light will totally internally reflect at the
core-cladding layer interface. Cladding layers may also be used to
provide the benefit of at least one of increased rigidity,
increased flexural modulus, increased impact resistance, anti-glare
properties, provide an intermediate layer for combining with other
layers such as in the case of a cladding functioning as a tie layer
or a base or substrate for an anti-reflection coating, a substrate
for an optical component such as a polarizer, liquid crystal
material, increased scratch resistance, provide additional
functionality (such as a low-tack adhesive to bond the lightguide
region to another element, a window "cling type" film such as a
highly plasticized PVC). The cladding layer may be an adhesive,
such as a low refractive index silicone adhesive which is optically
coupled to another element of the device, the lightguide, the
lightguide region, the light mixing region, the light input
coupler, or a combination of one or more of the aforementioned
elements or regions. In one embodiment, a cladding layer is
optically coupled to a rear polarizer in a backlit liquid crystal
display. In another embodiment, the cladding layer is optically
coupled to a polarizer or outer surface of a front-lit display such
as an electrophoretic display, e-book display, e-reader display,
MEMs type display, electronic paper displays such as E-Ink.RTM.
display by E Ink Corporation, reflective or partially reflective
LCD display, cholesteric display, or other display capable of being
illuminated from the front. In another embodiment, the cladding
layer is an adhesive that bonds the lightguide or lightguide region
to a component such as a substrate (glass or polymer), optical
element (such as a polarizer, retarder film, diffuser film,
brightness enhancement film, protective film (such as a protective
polycarbonate film), the light input coupler, coupling lightguides,
or other element of the light emitting device. In one embodiment,
the cladding layer is separated from the lightguide or lightguide
region core layer by at least one additional layer or adhesive.
[0241] In one embodiment, a region of cladding material is removed
or is absent in the region wherein the lightguide layer or
lightguide is optically coupled to another region of the lightguide
wherein the cladding is removed or absent such that light can
couple between the two regions. In one embodiment, the cladding is
removed or absent in a region near an edge of a lightguide,
lightguide region, strip or region cut from a lightguide region, or
coupling lightguide such that light nearing the edge of the
lightguide can be redirected by folding or bending the region back
onto a region of the lightguide wherein the cladding has been
removed where the regions are optically coupled together. In
another embodiment, the cladding is removed or absent in the region
disposed between the lightguide regions of two coupling lightguides
disposed to receive light from a light source or near a light input
surface. By removing or not applying or disposing a cladding in the
region between the input ends of two or more coupling lightguides
disposed to receive light from a light source, light is not
directly coupled into the cladding region edge.
Cladding Location
[0242] In one embodiment, the cladding region is optically coupled
to at least one selected from the group: lightguide, lightguide
region, light mixing region, one surface of the lightguide, two
surfaces of the lightguide, light input coupler, coupling
lightguides, and outer surface of the film. In another embodiment,
the cladding is disposed in optical contact with the lightguide,
lightguide region, or layer or layers optically coupled to the
lightguide and the cladding material is not disposed on one or more
coupling lightguides. In one embodiment, the coupling lightguides
do not comprise a cladding layer between the core regions in the
region near the light input surface or light source. In another
embodiment, the core regions may be pressed or held together and
the edges may be cut and/or polished after stacking or assembly to
form a light input surface or a light turning edge that is flat,
curved, or a combination thereof. In another embodiment, the
cladding layer is a pressure sensitive adhesive and the release
liner for the pressure sensitive adhesive is selectively removed in
the region of one or more coupling lightguides that are stacked or
aligned together into an array such that the cladding helps
maintain the relative position of the coupling lightguides relative
to each other. In another embodiment, the protective liner is
removed from the inner cladding regions of the coupling lightguides
and is left on one or both outer surfaces of the outer coupling
lightguides. In another embodiment, the protective liner of at
least one outer surface of the outer coupling lightguides is
removed such that the stack of coupling lightguides may be bonded
to one of the following: a circuit board, a non-folded coupling
lightguide, a light collimating optical element, a light turning
optical element, a light coupling optical element, a flexible
connector or substrate for a display or touchscreen, a second array
of stacked coupling lightguides, a light input coupler housing, a
light emitting device housing, a thermal transfer element, a heat
sink, a light source, an alignment guide, a registration guide or
component comprising a window for the light input surface, and any
suitable element disposed on and/or physically coupled to an
element of the light input surface or light emitting device. In one
embodiment, the coupling lightguides do not comprise a cladding
region on either planar side and optical loss at the bends or folds
in the coupling lightguides is reduced. In another embodiment, the
coupling lightguides do not comprise a cladding region on either
planar side and the light input surface input coupling efficiency
is increased due to the light input surface area having a higher
concentration of lightguide received surface relative to a
lightguide with at least one cladding. In a further embodiment, the
light emitting region has at least one cladding region or layer and
the percentage of the area of the light input surface of the
coupling lightguides disposed to transmit light into the lightguide
portion of the coupling lightguides is greater than one of the
following: 70%, 80%, 85%, 90%, 95%, 98% and 99%. The cladding may
be on one side only of the lightguide or the light emitting device
could be designed to be optically coupled to a material with a
refractive index lower than the lightguide, such as in the case
with a plasticized PVC film (n=1.53) (or other low-tack material)
temporarily adhered to a glass window (n=1.51).
[0243] In one embodiment, the cladding on at least one surface of
the lightguide is applied (such as coated or co-extruded) and the
cladding on the coupling lightguides is subsequently removed. In a
further embodiment, the cladding applied on the surface of the
lightguide (or the lightguide is applied onto the surface of the
cladding) such that the regions corresponding to the coupling
lightguides do not have a cladding. For example, the cladding
material could be extruded or coated onto a lightguide film in a
central region wherein the outer sides of the film will comprise
coupling lightguides. Similarly, the cladding may be absent on the
coupling lightguides in the region disposed in close proximity to
one or more light sources or the light input surface.
[0244] In one embodiment, two or more core regions of the coupling
lightguides do not comprise a cladding region between the core
regions in a region of the coupling lightguide disposed within a
distance selected from the group: 1 millimeter, 2 millimeters, 4
millimeters, and 8 millimeters from the light input surface edge of
the coupling lightguides. In a further embodiment, two or more core
regions of the coupling lightguides do not comprise a cladding
region between the core regions in a region of the coupling
lightguide disposed within a distance selected from the group: 10%,
20%, 50%, 100%, 200%, and 300% of the combined thicknesses of the
cores of the coupling lightguides disposed to receive light from
the light source from the light input surface edge of the coupling
lightguides. In one embodiment, the coupling lightguides in the
region proximate the light input surface do not comprise cladding
between the core regions (but may contain cladding on the outer
surfaces of the collection of coupling lightguides) and the
coupling lightguides are optically coupled together with an
index-matching adhesive or material or the coupling lightguides are
optically bonded, fused, or thermo-mechanically welded together by
applying heat and pressure. In a further embodiment, a light source
is disposed at a distance to the light input surface of the
coupling lightguides less than one selected from the group: 0.5
millimeter, 1 millimeter, 2 millimeters, 4 millimeters, and 6
millimeters and the dimension of the light input surface in the
first direction parallel to the thickness direction of the coupling
lightguides is greater than one selected from the group: 100%,
110%, 120%, 130%, 150%, 180%, and 200% the dimension of the light
emitting surface of the light source in the first direction. In
another embodiment, disposing an index-matching material between
the core regions of the coupling lightguides or optically coupling
or boding the coupling lightguides together in the region proximate
the light source optically couples at least one selected from the
group: 10%, 20%, 30%, 40%, and 50% more light into the coupling
lightguides than would be coupled into the coupling lightguides
with the cladding regions extending substantially to the light
input edge of the coupling lightguide. In one embodiment, the
index-matching adhesive or material has a refractive index
difference from the core region less than one selected from the
group: 0.1. 0.08, 0.05, and 0.02. In another embodiment, the
index-matching adhesive or material has a refractive index greater
by less than one selected from the group: 0.1, 0.08, 0.05, and 0.02
the refractive index of the core region. In a further embodiment, a
cladding region is disposed between a first set of core regions of
coupling lightguides for a second set of coupling lightguides an
index-matching region is disposed between the core regions of the
coupling lightguides or they are fused together. In a further
embodiment, the coupling lightguides disposed to receive light from
the geometric center of the light emitting area of the light source
within a first angle of the optical axis of the light source have
cladding regions disposed between the core regions, and the core
regions at angles larger than the first angle have index-matching
regions disposed between the core regions of the coupling
lightguides or they are fused together. In one embodiment, the
first angle is selected from the group: 10 degrees, 20 degrees, 30
degrees, 40 degrees, 50 degrees, and 60 degrees. In the
aforementioned embodiments, the cladding region may be a low
refractive index material or air. In a further embodiment, the
total thickness of the coupling lightguides in the region disposed
to receive light from a light source to be coupled into the
coupling lightguides is less than n times the thickness of the
lightguide region where n is the number of coupling lightguides. In
a further embodiment, the total thickness of the coupling
lightguides in the region disposed to receive light from a light
source to be coupled into the coupling lightguides is substantially
equal to n times the thickness of the lightguide layer within the
lightguide region.
Cladding Layer Materials
[0245] In one embodiment, the cladding layer comprises an adhesive
such as a silicone-based adhesive, acrylate-based adhesive, epoxy,
radiation curable adhesive. UV curable adhesive, or other light
transmitting adhesive. The cladding layer material may comprise
light scattering domains and may scatter light anisotropically or
isotropically. In one embodiment, the cladding layer is an adhesive
such as those described in U.S. Pat. No. 6,727,313. In another
embodiment, the cladding material comprises domains less than 200
nm in size with a low refractive index such as those described in
U.S. Pat. No. 6,773,801. Other low refractive index materials,
fluoropolymer materials, polymers and adhesives may be used such as
those disclosed U.S. Pat. Nos. 6,887,334 and 6,827,886 and U.S.
patent application Ser. No. 11/795,534.
[0246] Fluoropolymer materials may be used as a low refractive
index cladding material and may be broadly categorized into one of
two basic classes. A first class includes those amorphous
fluoropolymers comprising interpolymerized units derived from
vinylidene fluoride (VDF) and hexafluoropropylene (HFP) and
optionally tetrafluoroethylene (TFE) monomers. Examples of such are
commercially available from 3M Company as Dyneon.TM.
Fluoroelastomer FC 2145 and FT 2430. Additional amorphous
fluoropolymers that can be used in embodiments are, for example,
VDF-chlorotrifluoroethylene copolymers. One such
VDF-chlorotrifluoroethylene copolymer is commercially known as
Kel-F.TM. 3700, available from 3M Company. As used herein,
amorphous fluoropolymers are materials that contain essentially no
crystallinity or possess no significant melting point as determined
for example by differential scanning calorimetry (DSC). For the
purpose of this discussion, a copolymer is defined as a polymeric
material resulting from the simultaneous polymerization of two or
more dissimilar monomers and a homopolymer is a polymeric material
resulting from the polymerization of a single monomer.
[0247] The second significant class of fluoropolymers useful in an
embodiment are those homo and copolymers based on fluorinated
monomers such as TFE or VDF which do contain a crystalline melting
point such as polyvinylidene fluoride (PVDF, available commercially
from 3M company as Dyneon.TM. PVDF, or more preferable
thermoplastic copolymers of TEE such as those based on the
crystalline microstructure of TFE-HFP-VDE Examples of such polymers
are those available from 3M under the trade name Dyneon.TM.
Fluoroplastics THV.TM. 200.
[0248] A general description and preparation of these classes of
fluoropolymers can be found in Encyclopedia Chemical Technology,
Fluorocarbon Elastomers, Kirk-Othmer (1993), or in Modern
Fluoropolymers, J. Scheirs Ed, (1997), J Wiley Science, Chapters 2,
13, and 32. (ISBN 0-471-97055-7).
[0249] In one embodiment, the fluoropolymers are copolymers formed
front the constituent monomers known as tetrafluoroethylene
("TFE"), hexafluoropropylene ("HFP"), and vinylidene fluoride
("VdF," "VF2,"). The monomer structures for these constituents are
shown below as (1), (2) and (3):
TFE: CF2=CF2 (1)
VDF: CH2=CF2 (2)
HFP: CF2=CF--CF3 (3)
[0250] In one embodiment, the preferred fluoropolymer consists of
at least two of the constituent monomers (HFP and VDF), and more
preferably all three of the constituents monomers in varying molar
amounts. Additional monomers not depicted above but may also be
useful in an embodiment include perfluorovinyl ether monomers of
the general structure: CF 2=CF OR f, wherein R f can be a branched
or linear perfluoroalkyl radical of 1-8 carbons and can itself
contain additional heteroatoms such as oxygen. Specific examples
are perfluoromethyl vinyl ether, perfluoropropyl vinyl ether, and
perfluoro(3-methoxy-propyl) vinyl ether. Additional monomer
examples are found in WO00/12754 to Worm, assigned to 3M, and U.S.
Pat. No. 5,214,100 to Carlson. Other fluoropolymer materials may be
used such as those disclosed in U.S. patent application Ser. No.
11/026,614.
[0251] In one embodiment, the cladding material is birefringent and
the refractive index in at least a first direction is less than
refractive index of the lightguide region, lightguide core, or
material to which it is optically coupled.
[0252] Collimated light propagating through a material may be
reduced in intensity after passing through the material due to
scattering (scattering loss coefficient), absorption (absorption
coefficient), or a combination of scattering and absorption
(attenuation coefficient). In one embodiment, the cladding
comprises a material with an average absorption coefficient for
collimated light less than one selected from the group: 0.03
cm.sup.-1, 0.02 cm.sup.-1, 0.01 cm.sup.-1, and 0.005 cm.sup.-1 over
the visible wavelength spectrum from 400 nanometers to 700
nanometers. In another embodiment, the cladding comprises a
material with an average scattering loss coefficient for collimated
light less than one selected from the group: 0.03 cm.sup.-1, 0.02
cm.sup.-1, 0.01 cm.sup.-1, and 0.005 cm.sup.-1 over the visible
wavelength spectrum from 400 nanometers to 700 nanometers. In
another embodiment, the cladding comprises a material with an
average attenuation coefficient for collimated light less than one
selected from the group: 0.03 cm.sup.-1, 0.02 cm.sup.-1, 0.01
cm.sup.-1, and 0.005 cm.sup.-1 over the visible wavelength spectrum
from 400 nanometers to 700 nanometers.
[0253] In a further embodiment, a lightguide comprises a hard
cladding layer that substantially protects a soft core layer (such
as a soft silicone or silicone elastomer).
[0254] In one embodiment, a lightguide comprises a core material
with a Durometer Shore A hardness (JIS) less than 50 and at least
one cladding layer with a Durometer Shore A hardness (BS) greater
than 50. In one embodiment, a lightguide comprises a core material
with an ASTM D638-10 Young's Modulus less than 2 MPa and at least
one cladding layer with an ASTM D638-10 Young's Modulus greater
than 2 MPa at 25 degrees Celsius. In another embodiment, a
lightguide comprises a core material with an ASTM D638-10 Young's
Modulus less than 1.5 MPa and at least one cladding layer with an
ASTM D638-10 Young's Modulus greater than 2 MPa at 25 degrees
Celsius. In a further embodiment, a lightguide comprises a core
material with an ASTM D638-10 Young's Modulus less than 1 MPa and
at least one cladding layer with an ASTM D638-10 Young's Modulus
greater than 2 MPa at 25 degrees Celsius.
[0255] In one embodiment, a lightguide comprises a core material
with an ASTM D638-10 Young's Modulus less than 2 MPa and the
lightguide film has an ASTM D638-10 Young's Modulus greater than 2
MPa at 25 degrees Celsius. In another embodiment, a lightguide
comprises a core material with an ASTM D638-10 Young's Modulus less
than 1.5 MPa and the lightguide film has an ASTM D638-10 Young's
Modulus greater than 2 MPa at 25 degrees Celsius. In one
embodiment, a lightguide comprises a core material with an ASTM
D638-10 Young's Modulus less than 1 MPa and the lightguide film has
an ASTM D638-10 Young's Modulus greater than 2 MPa at 25 degrees
Celsius.
Reflective Elements
[0256] In one embodiment, at least one of the light source, light
input surface, light input coupler, coupling lightguide, lightguide
region, and lightguide comprises a reflective element or surface
optically coupled to it, disposed adjacent to it, or disposed to
receive light from it wherein the reflective region is one selected
from the group: specularly reflecting region, diffusely reflecting
region, metallic coating on a region (such as an ITO coating,
Aluminized PET, Silver coating, etc.), multi-layer reflector
dichroic reflector, multi-layer polymeric reflector, giant
birefringent optical films, enhanced specular reflector films,
reflective ink or particles within a coating or layer, and a white
reflective film comprising at least one selected from the group:
titanium dioxide, barium sulfate, and voids. In another embodiment,
a light emitting device comprises a lightguide wherein at least one
light reflecting material selected from the group: a light
recycling element, a specularly reflective tape with a diffuse
reflectance (specular component included) greater than 70%, a
retroreflective film (such as a corner cube film or glass bead
based retroreflective film), white reflecting film, and aluminum
housing is disposed near or optically coupled at least one edge
region of the lightguide disposed to receive light from the
lightguide and redirect a first portion of light back into the
lightguide. In another embodiment, a light emitting device
comprises a lightguide wherein at least one light absorbing
material selected from the group: a light absorbing tape with a
diffuse reflectance (specular component included) less than 50%, a
region comprising a light absorbing dye or pigment, a region
comprising carbon black particles, a region comprising light
absorbing ink, paint, films or surfaces, and a black material is
disposed near or optically coupled at least one edge region of the
lightguide disposed to receive light from the lightguide and
redirect a first portion of light back into the lightguide. In a
further embodiment, a light reflecting material and a light
absorbing material of the aforementioned types is disposed near or
optically coupled at least one edge region of the lightguide
disposed to receive light from the lightguide and redirect a first
portion of light back into the lightguide and absorb a second
portion of incident light. In one embodiment, the light reflecting
or light absorbing material is in the form of a line of ink or tape
adhered onto the surface of the lightguide film. In one embodiment,
the light reflecting material is a specularly reflecting tape
adhered to the top surface, edge, and bottom surface of the
lightguide near the edge of the lightguide. In another embodiment,
the light absorbing material is a light absorbing tape adhered to
the top surface, edge, and bottom surface of the lightguide near
the edge of the lightguide. In another embodiment, the light
absorbing material is a light absorbing ink or paint (such as a
black acrylic based paint) adhered to at least one selected from
the group: edge, top surface near the edge, and bottom surface near
the edge of the lightguide
[0257] In one embodiment, the light emitting device is a backlight
illuminating a display or other object to be illuminated and the
light emitting region, lightguide, or lightguide region is disposed
between a reflective surface or element and the object to be
illuminated. In another embodiment, the reflective element is a
voided white PET film such as TETORON.RTM. film UX Series from THIN
(Japan). In one embodiment, the reflective element or surface has a
diffuse reflectance d/8 with the specular component included
(DR-SCI) measured with a Minolta CM508D spectrometer greater than
one selected from the group: 60%, 70%, 80%, 90%, and 95%. In
another embodiment, the reflective element or surface has a diffuse
reflectance d/8 with the specular component excluded (DR-SCE)
measured with a Minolta CM508D spectrometer greater than one
selected from the group: 60%, 70%, 80%, 90%, and 95%. In another
embodiment, the reflective element or surface has a specular
reflectance greater than one selected from the group: 60%, 70%,
80%, 90%, and 95%. The specular reflectance, as defined herein, is
the percentage of light reflected from a surface illuminated by a
532 nanometer laser that is within a 10 degree (full angle) cone
centered about the optical axis of the reflected light. This can be
measured by using an integrating sphere wherein the aperture
opening for the integrating sphere is positioned at a distance from
the point of reflection such that the angular extent of the
captured light is 10 degrees full angle. The percent reflection is
measured against a reflectance standard with a known specular
reflectance, a reflectance standard, film, or object that have
extremely low levels of scattering.
Light Reflecting Optical Element is Also a Second Element
[0258] In addition to reflecting incident light, in one embodiment,
the light reflecting element is also at least one second element
selected from the group: light blocking element, low contact area
covering element, housing element, light collimating optical
element, light turning optical element and thermal transfer
element. In another embodiment, the light reflecting optical
element is a second element within a region of the light reflecting
optical element. In a further embodiment, the light reflecting
optical element comprises a bend region, tab region, hole region,
layer region, or extended region that is, or forms a component
thereof, a second element. For example, a diffuse light reflecting
element comprising a voided PET diffuse reflecting film may be
disposed adjacent the lightguide region to provide diffuse
reflection and the film may further comprise a specular reflecting
metallized coating on an extended region of the film that is bent
and functions to collimate incident light from the light source. In
another embodiment, the second element or second region of the
light reflecting optical element is contiguous with one or more
regions of the light reflecting optical element. In a further
embodiment, the light reflecting optical element is a region,
coating, element or layer physically coupled to a second element.
In another embodiment, the second element is a region, coating,
element or layer physically coupled to a light reflecting optical
element. For example, in one embodiment, the light reflecting
optical element is a metalized PET film adhered to the back of a
transparent, low contact area film comprising polyurethane and a
surface relief profile wherein the film combination extends from
beneath the lightguide region to wrap around one or more coupling
lightguides. In a further embodiment, the light reflecting optical
element is physically and/or optically coupled to the film-based
lightguide and is cut during the same cutting process that
generates the coupling lightguides and the light reflecting optical
element is cut into regions that are angled, curved or subsequently
angled or curved to form a light collimating optical element or a
light turning optical element. The size, shape, quantity,
orientation, material and location of the tab regions, light
reflecting regions or other regions of the light reflecting optical
element may vary as needed to provide optical (efficiency, light
collimation, light redirection, etc.), mechanical (rigidity,
connection with other elements, alignment, ease of manufacture
etc.), or system (reduced volume, increased efficiency, additional
functionality such as color mixing) benefits such as is known in
the art of optical elements, displays, light fixtures, etc. For
example, the tab regions of a light reflecting optical element that
specularly reflects incident light may comprise a parabolic,
polynomial or other geometrical cross-sectional shape such that the
angular FWHM intensity, light flux, orientation, uniformity, or
light profile is controlled. For example, the curved
cross-sectional shape of one or more tab regions may be that of a
compound parabolic concentrator. In another embodiment, the light
reflecting optical element comprises hole regions, tab regions,
adhesive regions or other alignment, physical coupling, optical
coupling, or positioning regions that correspond in shape, size, or
location to other elements of the light emitting device to
facilitate at least one selected from the group: alignment,
position, adhesion, physically coupling, or optically coupling with
a second element or component of the light emitting device. For
example, the light reflecting optical element may be a specularly
reflecting or mirror-like metallized PET that is disposed beneath a
substantially planar light emitting region and extends into the
region near the light source and comprises extended tabs or folding
regions that fold and are optically coupled to at least one outer
surface of a light collimating element. In this embodiment, the
light reflecting optical element is also a component of a light
collimating optical element. In another embodiment, the light
reflecting optical element is a specularly reflecting metallized
PET film that is optically coupled to a non-folded coupling
lightguide using a pressure sensitive adhesive and is extended
toward the light source such that the extended region is optically
coupled to an angled surface of a light collimating optical element
that collimates a portion of the light from the light source in the
plane perpendicular to the plane comprising the surface of the
non-folded coupling lightguide optically coupled to the light
reflecting optical element.
[0259] In one embodiment, the light reflecting element is also a
light blocking element wherein the light reflecting element blocks
a first portion of light escaping the light input coupler, coupling
lightguide, light source, light redirecting optical element, light
collimating optical element, light mixing region, lightguide
region. In another embodiment, the light reflecting element
prevents the visibility of stray light, undesirable light, or a
predetermined area of light emitting or redirecting surface from
reaching the viewer of a display, sign, or a light emitting device.
For example, a metallized specularly reflecting PET film may be
disposed to reflect light from one side of the lightguide region
back toward the lightguide region and also extend to wrap around
the stack of coupling lightguide using the PSA optically coupled to
the coupling lightguides (which may be a cladding layer for the
lightguides) to adhere the metallized PET film to the stack and
block stray light escaping from the coupling lightguides and
becoming visible.
[0260] In one embodiment, the light reflecting element is also a
low contact area covering. For example, in one embodiment, the
light reflecting element is a metallized PET film comprising a
methacrylate based coating that comprises surface relief features.
In this embodiment, the light reflecting element may wrap around
the stack without significantly extracting light from the coupling
lightguides when air is used as a cladding region. In another
embodiment, the reflective element has non-planar regions such that
the reflective surface is not flat and the contact area between the
light reflecting film and one or more coupling lightguides or
lightguide regions is a low percentage of the exposed surface
area.
[0261] In another embodiment, the light reflecting element is also
a housing element. For example, in one embodiment, the light
reflecting element is a reflective coating on the inner wall of the
housing for the coupling lightguides. The housing may have
reflective surfaces or reflect light from within (such as an
internal reflecting layer or material). The light reflecting
element may be the housing for the lightguide region or other
lightguide or component of the light emitting device.
[0262] In a further embodiment, the light reflecting element is
also a light collimating optical element disposed to reduce the
angular full-width at half maximum intensity of light from a light
source before the light enters one or more coupling lightguides. In
one embodiment, the light reflecting optical element is a
specularly reflecting multilayer polymeric film (such as a giant
birefringent optical film) disposed on one side of the light
emitting region of lightguide film and extended in a direction
toward the light source with folds or curved regions that are bent
or folded to form angled or curved shapes that receive light from
the light source and reflect and collimate light toward the input
surface of one or more coupling lightguides. More than one fold or
curved region may be used to provide different shapes or
orientations of light reflecting surfaces for different regions
disposed to receive light from the light source. For example, an
enhanced specularly reflecting multilayer polymer film (such as a
giant birefringent optical film) disposed and optically coupled to
the lightguide region of a film-based lightguide using a low
refractive index PSA cladding layer may extend toward the light
source and comprise a first extended region that wraps around the
cladding region to protect and block stray light and further
comprise an extended region that comprises two tabs that are folded
and a cavity wherein the light source may be disposed such that
light from the light source within a first plane is collimated by
the extended region tabs. In one embodiment, the use of the light
reflecting element that is physically coupled to another component
in the light emitting device (such as the film-based lightguide or
coupling lightguides) provides an anchor or registration assistance
for aligning the light collimating optical element tabs or
reflective regions of the light reflecting element.
[0263] In a further embodiment, the light reflecting element is
also a light turning optical element disposed to redirect the
optical axis of light in a first plane. In one embodiment, the
light reflecting optical element is a specularly reflecting
multilayer polymer film (such as a giant birefringent optical film)
disposed on one side of the light emitting region of lightguide
film and extended in a direction toward the light source with folds
or curved regions that are bent or folded to form angled or curved
shapes that receive light from the light source and reflect and
redirect the optical axis of the incident light toward the input
surface of one or more coupling lightguides. More than one fold or
curved region may be used to provide different shapes or
orientations of light reflecting surfaces for different regions
disposed to receive light from the light source. For example, a
specularly reflecting multilayer polymer film disposed and
optically coupled to the lightguide region of a film-based
lightguide using a low refractive index PSA cladding layer may
extend toward the light source and comprise an first extended
region that wraps around the cladding region to protect and block
stray light and further comprise an extended region that comprises
two tabs that are folded and a cavity wherein the light source may
be disposed such that optical axis of the light from the light
source within a first plane in a first direction is redirected by
the extended region tabs into a second direction different than the
first direction. In one embodiment, the use of the light reflecting
element that is physically coupled to another component in the
light emitting device (such as the film-based lightguide or
coupling lightguides) provides an anchor or registration assistance
for aligning the light turning optical element tabs or reflective
regions of the light reflecting element.
[0264] In a further embodiment, the light reflecting element is
also a thermal transfer element that transfers heat away from the
light source. For example, in one embodiment, the light reflecting
element is a reflective aluminum housing disposed on one side of
the lightguide region and extending to and thermally coupled to a
circuit board that is thermally coupled to the light source such
that heat from the light source is thermally transferred to the
aluminum. In a another example, the light reflecting optical
element is a high reflectance polished region of an aluminum sheet
that further comprises (or is thermally coupled to) an extrusion
region with fins or heat sink extensions, in another embodiment,
the thermal transfer element is an aluminum extrusion comprising
the coupling lightguide in an interior region wherein the inner
surface of the extrusion is a light reflecting optical element
disposed to reflect light received from the coupling lightguides
back toward the coupling lightguides. In another embodiment, the
thermal transfer element is an aluminum extrusion comprising
coupling lightguides in an interior region wherein the extrusion
further comprises a light collimating reflective surface disposed
to collimate light from the light source.
Protective Layers
[0265] In one embodiment, at least one selected from the group:
light input surface, light input coupler, coupling lightguide,
lightguide region, and lightguide comprises a protective element or
layer optically coupled to it, physically coupled to it, disposed
adjacent to it, or disposed between it and a light emitting surface
of the light emitting device. A protective film element can have a
higher scratch resistance, higher impact resistance, hardcoating
layer, impact absorbing layer or other layer or element suitable to
protect at least one selected from the group: light input surface,
light input coupler, coupling lightguide, lightguide region, and
lightguide from scratches, impacts, dropping the device, and
interaction with sharp objects, etc.
Coupling Light into the Surface of the Coupling Lightguide
[0266] In one embodiment, the light input surface of the light
input coupler is at least one surface of at least one coupling
lightguide. In one embodiment, light is coupled into a coupling
lightguide such that it remains in the lightguide for multiple
total internal reflections by at least one optical element or
feature on at least one surface or optically coupled to at least
one surface comprising an optical region selected from the group:
lens, prismatic lens, prismatic film, diffraction grating,
holographic optical element, diffractive optical element, diffuser,
anisotropic diffuser, refractive surface relief features,
diffractive surface relief features, volumetric light re-directing
features, micro-scale volumetric or surface relief features,
nano-scale volumetric or surface relief features, and
total-internal-reflection volumetric or surface features. The
optical element or feature may be incorporated on one or several
coupling lightguides in a stacked or predetermined physically
arranged distribution of coupling lightguides. In one embodiment,
the optical element or feature is arranged spatially in a pattern
within or on one coupling lightguide or across multiple coupling
lightguides. In one embodiment, the coupling efficiency of an
optical element or feature is greater than one selected from the
group: 50%, 60%, 70%, 80%, and 90% for a wavelength range selected
from one selected from the group: 350 nm-400 nm, 400 nm-700 nm, 450
nm-490 nm, 490 nm-560 nm, and 635 nm-700 nm. The coupling
efficiency as defined herein is the percent of incident light from
a light source disposed to direct light onto at least one coupling
lightguide which is coupled into the at least one coupling
lightguide disposed to receive light from the light source which
remains within the coupling lightguide at an angle greater than the
critical angle further along in the region of the lightguide just
past the light input surface region. In one embodiment, two or more
coupling lightguides are stacked or bundled together wherein they
each have an optical element or feature disposed to couple light
into the coupling lightguide and the optical element or feature has
a coupling efficiency less than one selected from the group: 50%,
60%, 70%, 80%, and 90% for a wavelength range selected from one
selected from the group: 350 nm-400 nm, 400 nm-700 nm, 450 nm-490
nm, 490 nm-560 nm, and 635 nm-700 nm. By stacking a group of
coupling lightguides, for example, one can use lower coupling
efficiencies to enable a portion of the incident light to pass
through a first coupling lightguide onto a second coupling
lightguide to allow light to be coupled into the second coupling
lightguide. In one embodiment, the coupling efficiency is graded or
varies in a first direction through an arrangement of coupling
lightguides and a light reflecting element or region is disposed on
the opposite side of the arrangement of coupling lightguides
disposed to reflect a portion of incident light back through the
coupling lightguides.
Coupling Light into Two or More Surfaces
[0267] In one embodiment, light is coupled through light input
couplers, coupling lightguides, optical elements, or a combination
thereof to at least two surfaces or surface regions of a at least
one lightguide in a light emitting device. In another embodiment,
the light coupled through the surface of a lightguide or lightguide
region is directed by the light extraction features into an angular
range different than that of the light directed by the same or
different light extraction features from light coupled through a
second surface or second surface region of a lightguide or
lightguide region of a light emitting device. In another
embodiment, a first light extracting region comprising a first set
of light re-directing features or light extraction features that
directs light incident through a first surface or edge into a first
range of angles upon exiting the light emitting surface of the
lightguide and a second light extracting region comprises a second
set of light re-directing or light extraction features that direct
light incident through a second surface or edge into a second range
of angles upon exiting the light emitting surface of the
lightguide. Variations in the light re-directing features include,
but are not limited to, feature height, shape, orientation,
density, width, length, material, angle of a surface, location in
the x, y, and z direction and include dispersed phase domains,
grooves, pits, micro-lenses, prismatic elements, air cavities,
hollow microspheres, dispersed microspheres, and other known light
extraction features or elements. In another embodiment, a light
emitting device comprises at least one lightguide and a first light
source disposed to couple light through a surface of at least one
lightguide and a second light source disposed to couple light
through the edge of at least one lightguide wherein the coupling
mechanism is at least one selected from the group: light input
couplers, optical element, coupling lightguide, optical components
or coupling lightguides optically coupled to a surface or edge,
diffractive optics, holographic optical element, diffraction
grating, Fresnel lens element, prismatic film, light redirecting
optic, and other optical element.
Light Input Couplers Disposed Near More than One Edge of a
Lightguide
[0268] In one embodiment, a light emitting device comprises a
plurality of light input couplers disposed to couple light into a
lightguide from at least two input regions disposed near two
different edges of a lightguide. In another embodiment, two light
input couplers are disposed on opposite sides of a lightguide. In
another embodiment, light input couplers are disposed on three or
four sides of a film-type lightguide. In a further embodiment, more
than one light input coupler, housing, or light input surface is
disposed to receive light from a single light source, light source
package, array of light sources or light source strip (such as a
substantially linear array of LEDs). For example, two housing for
two light input couplers disposed to couple light to two different
regions of a lightguide are disposed to receive light from a
substantially linear array of LEDs. In another embodiment a first
input surface comprising a first collection of coupling lightguides
optically coupled to a first region of a lightguide and a second
input surface comprising a second collection of coupling
lightguides optically coupled to a second region of a lightguide
different than the first region are disposed to receive light from
one selected from the group: the same light source, a plurality of
light sources, light sources in a package, an array or collection
of light sources, a linear array of light sources, one or more
LEDs, an LED package, a linear array of LEDs, and LEDs of multiple
colors.
Strip Folding Device
[0269] In one embodiment, the light emitting device comprises frame
members which assist in at least one of the folding or holding of
the coupling lightguides or strips. Methods for folding and holding
coupling lightguides such as film-based lightguides using frame
members are disclosed in International (PCT) Publication No. WO
2009/048863 and PCT application entitled "Illumination via flexible
thin films" filed on Jan. 26, 2010 by Anthony Nichols and Shawn
Pucylowski, and US Provisional patent applications serial numbers
61/147,215 and 61/147,237. In one embodiment, the coupling
lightguide folding (or bending) and/or holding (or housing) element
is formed from at least one selected from the group: rigid plastic
material, black colored material, opaque material, semi-transparent
material, metal foil, metal sheet, aluminum sheet, and aluminum
foil. In one embodiment, the folding or holding material has a
flexural rigidity or (flexural modulus) at least twice the flexural
rigidity (or modulus) of the film or coupling lightguides which it
folds or holds.
Housing or Holding Device for Light Input Coupler
[0270] In one embodiment, a light emitting device comprises a
housing or holding device that holds or contains at least part of a
light input coupler and light source. The housing or holding device
may house or contain within at least one selected from the group:
light input coupler, light source, coupling lightguides,
lightguide, optical components, electrical components, heat sink or
other thermal components, attachment mechanisms, registration
mechanisms, folding mechanisms devices, and frames. The housing or
holding device may comprise a plurality of components or any
combination of the aforementioned components. The housing or
holding device may serve one or more of functions selected from the
group: protect from dust and debris contamination, provide
air-tight seat, provide a water-tight seal, house or contain
components, provide a safety housing for electrical or optical
components, assist with the folding or bending of the coupling
lightguides, assist in the alignment or holding of the lightguide,
coupling lightguide, light source or light input coupler relative
to another component, maintain the arrangement of the coupling
lightguides, recycle light (such as with reflecting inner walls),
provide attachment mechanisms for attaching the light emitting
device to an external object or surface, provide an opaque
container such that stray light does not escape through specific
regions, provide a translucent surface for displaying indicia or
providing illumination to an object external to the light emitting
device, comprise a connector for release and interchangeability of
components, and provide a latch or connector to connect with other
holding devices or housings.
[0271] In one embodiment, the coupling lightguides are terminated
within the housing or holding element. In another embodiment, the
inner surface of the housing or holding element has a specular or
diffuse reflectance greater than 50% and the inner surface appears
white or mirror-like. In another embodiment, the outer surface of
the housing or holding device has a specular or diffuse reflectance
greater than 50% and the outer surface appears white or
mirror-like. In another embodiment, at least one wall of the
housing or holding device has a specular or diffuse reflectance
less than 50% and the inner surface appears gray, black or like a
very dark mirror. In another embodiment, at least one wall or
surface of the housing or holding device is opaque and has a
luminous transmittance measured according to ASTM D1003 of less
than 50%. In another embodiment, at least one wall or surface of
the housing or holding device has a luminous transmittance measured
according to ASTM D1003 greater than 30% and the light exiting the
wall or surface from the light source within the housing or holding
device provides illumination for a component of the light emitting
device, illumination for an object external to the light emitting
device, or illumination of a surface to display a sign, indicia,
passive display, a second display or indicia, or an active display
such as providing backlight illumination for an LCD.
[0272] In one embodiment, the housing or holding device comprises
at least one selected from the group: connector, pin, clip, latch,
adhesive region, clamp, joining mechanism, and other connecting
element or mechanical means to connect or hold the housing or
holding device to one or more selected from the group: another
housing or holding device, lightguide, coupling lightguide, film,
strip, cartridge, removable component or components, an exterior
surface such as a window or automobile, light source, electronics
or electrical component, the circuit board for the electronics or
light source such as an LED, heat sink or other thermal control
element, frame of the light emitting device, and other component of
the light emitting device.
[0273] In a another embodiment, the input ends and output ends of
the coupling lightguides are held in physical contact with the
relative position maintaining elements by at least one selected
from the group: magnetic grips, mechanical grips, clamps, screws,
mechanical adhesion, chemical adhesion, dispersive adhesion,
diffusive adhesion, electrostatic adhesion, vacuum holding, or an
adhesive.
Curved or Flexible Housing
[0274] In another embodiment, the housing comprises at least one
curved surface. A curved surface can permit non-linear shapes or
devices or facilitate incorporating non-planer or bent lightguides
or coupling lightguides. In one embodiment, a light emitting device
comprises a housing with at least one curved surface wherein the
housing comprises curved or bent coupling lightguides. In another
embodiment, the housing is flexible such that it may be bent
temporarily, permanently or semi-permanently. By using a flexible
housing, for example, the light emitting device may be able to be
bent such that the light emitting surface is curved along with the
housing, the light emitting area may curve around a bend in a wall
or corner, for example. In one embodiment, the housing or
lightguide may be bent temporarily such that the initial shape is
substantially restored (bending a long housing to get it through a
door for example). In another embodiment, the housing or lightguide
may be bent permanently or semi-permanently such that the bent
shape is substantially sustained after release (such as when it is
desired to have a curved light emitting device to provide a curved
sign or display, for example).
Housing Including a Thermal Transfer Element
[0275] In one embodiment, the housing comprises a thermal transfer
element disposed to transfer heat from a component within the
housing to an outer surface of the housing. In another embodiment,
the thermal transfer element is one selected from the group: heat
sink, metallic or ceramic element, fan, heat pipe, synthetic jet,
air jet producing actuator, active cooling element, passive cooling
element, rear portion of a metal core or other conductive circuit
board, thermally conductive adhesive, or other component known to
thermally conduct heat. In one embodiment, the thermal transfer
element has a thermal conductivity (W/(mK)) greater than one
selected from the group: 0.2, 0.5, 0.7, 1, 3, 5, 50, 100, 120, 180,
237, 300, and 400.
Size of the Housing or Coupling Lightguide Holding Device
[0276] In one embodiment, the sizes of the two smaller dimensions
of the housing or coupling lightguide holding device are less than
one selected from the group: 500, 400, 300, 200, 100, 50, 25, 10,
and 5 times the thickness of the lightguide or coupling
lightguides. In another embodiment, at least one dimension of the
housing or lightguide holding device is smaller due to the use of
more than one light input coupler disposed along an edge of the
lightguide. In this embodiment, the thickness of the housing or
holding device can be reduced because for a fixed number of strips
or coupling lightguides, they can be arranged into multiple smaller
stacks instead of a single larger stack. This also enables more
light to be coupled into the lightguide by using multiple light
input couplers and light sources.
Low Contact Area Cover
[0277] In one embodiment, a low contact area cover is disposed
between at least one coupling lightguide and the exterior to the
light emitting device. The low contact area cover or wrap provides
a low surface area of contact with a region of the lightguide or a
coupling lightguide and may further provide at least one selected
from the group: protection from fingerprints, protection from dust
or air contaminants, protection from moisture, protection from
internal or external objects that would decouple or absorb more
light than the low contact area cover when in contact in one or
more regions with one or more coupling lightguides, provide a means
for holding or containing at least one coupling lightguide, hold
the relative position of one or more coupling lightguides, and
prevent the coupling lightguides from unfolding into a larger
volume or contact with a surface that could de-couple or absorb
light.
[0278] In another embodiment, the low contact area cover is
disposed between the outer surface of the light emitting device and
the regions of the coupling lightguides disposed between the fold
or bend region and the lightguide or light mixing region. In a
further embodiment, the low contact area cover is disposed between
the outer surface of the light emitting device and the regions of
the coupling lightguides disposed between the light input surface
of the coupling lightguides and the lightguide or light mixing
region, in another embodiment, the low contact area cover is
disposed between the outer surface of the light emitting device and
a portion of the regions of the coupling lightguides not enclosed
by a housing, protective cover, or other component disposed between
the coupling lightguides and the outer surface of the light
emitting device. In one embodiment, the low contact area cover is
the housing, relative position maintaining element, or a portion of
the housing or relative positioning maintaining element.
Film-Based Low Contact Area Cover
[0279] In one embodiment the low contact area cover is a film with
at least one of a lower refractive index than the refractive index
of the outer material of the coupling lightguide disposed near the
low contact area cover, and a surface relief pattern or structure
on the surface of the film-based low contact area cover disposed
near at least one coupling lightguide. In one embodiment, the low
contact area comprises convex or protruding surface relief features
disposed near at least one outer surface of at least one coupling
lightguide and the average percentage of the area disposed adjacent
to an outer surface of a coupling lightguide or the lightguide that
is in physical contact with the surface relief features is less
than one of the following: 70%, 50%, 30%, 10%, 5%, and 1%. In one
embodiment, a convex surface relief profile designed to have a low
contact area with a surface of the coupling lightguide will at
least one selected from the group: extract, absorb, scatter, or
otherwise alter the intensity or direction of a lower percentage of
light propagating within the coupling lightguide than a flat
surface of the same material in one embodiment, the surface relief
profile is at least one selected from the group: random,
semi-random, ordered, regular in one or 2 directions, holographic,
tailored, comprise cones, truncated polyhedrons, truncated
hemispheres, truncated cones, truncated pyramids, pyramids, prisms,
pointed shapes, round tipped shapes, rods, cylinders, hemispheres,
and other geometrical shapes. In one embodiment, the low contact
area cover material or film is at least one selected from the
group: transparent, translucent, opaque, light absorbing, light
reflecting, substantially black, substantially white, has a diffuse
reflectance specular component included greater than 70%, has a
diffuse reflectance specular component included less than 70%, has
an ASTM D1003 luminous transmittance less than 30%, has an ASTM
D1003 luminous transmittance greater than 30%, absorbs at least 50%
of the incident light, absorbs less than 50% of the incident light,
has an electrical sheet resistance less than 10 ohms per square,
and have an electrical sheet resistance greater than 10 ohms per
square.
[0280] In another embodiment, the low contact area cover is a film
with a thickness less than one selected from the group: 600
microns, 500 microns, 400 microns, 300 microns, 200 microns, 100
microns, and 50 microns.
Wrap Around Low Contact Area Cover
[0281] In a further embodiment, the low contact area cover is the
inner surface or physically coupled to a surface of a housing,
holding device, or relative position maintaining element. In a
further embodiment, the low contact area cover is a film which
wraps around at least one coupling lightguide such that at least
one lateral edge and at least one lateral surface is substantially
covered such that the low contact area cover is disposed between
the coupling lightguide and the outer surface of the device.
[0282] In another embodiment, a film-based lightguide comprises a
low contact area cover wrapped around a first group of coupling
lightguides wherein the low contact area cover is physically
coupled to at least one selected from the group: lightguide,
lightguide film, light input coupler, lightguide, housing, and
thermal transfer element by a low contact area cover physical
coupling mechanism. In another embodiment, the light emitting
device comprises a first cylindrical tension rod disposed to apply
tension to the low contact area cover film and hold the coupling
lightguides close together and close to the lightguide such that
the light input coupler has a lower profile. In another embodiment,
the low contact area cover can be pulled taught after physically
coupling to at least one selected from the group: lightguide,
lightguide film, light input coupler, lightguide, housing, thermal
transfer element, and other element or housing by moving the first
cylindrical tension rod away from a second tension bar or away from
a physical coupling point of the mechanism holding the tension bar
such as a brace. Other shapes and forms for the tension forming
element may be used such as a rod with a rectangular cross-section,
a hemispherical cross-section, or other element longer in a first
direction capable of providing tension when translated or
supporting tension when held stationary relative to other
components. In another embodiment, a first cylindrical tension rod
may be translated in a first direction to provide tension while
remaining in a brace region and the position of the cylindrical
tension rod may be locked or forced to remain in place by
tightening a screw for example. In another embodiment, the tension
forming element and the brace or physical coupling mechanism for
coupling it to the another component of the light input coupler
does not extend more than one selected from the group: 1
millimeter, 2 millimeters, 3 millimeters, 5 millimeters, 7
millimeters and 10 millimeters past at least one edge of the
lightguide in the direction parallel to the longer dimension of the
tension forming element.
Low Hardness Low Contact Area Cover
[0283] In another embodiment, the low contact area cover has an
ASTM D3363 pencil hardness under force from a 300 gram weight less
than the outer surface region of the coupling lightguide disposed
near the low contact area cover. In one embodiment, the low contact
area cover comprises a silicone, polyurethane, rubber, or
thermoplastic polyurethane with a surface relief pattern or
structure. In a further embodiment, the ASTM D3363 pencil hardness
under force from a 300 gram weight of the low contact area cover is
at least 2 grades less than the outer surface region of the
coupling lightguide disposed near the low contact area cover.
Physical Coupling Mechanism for Low Contact Area Cover
[0284] In one embodiment, the low contact area cover is physically
coupled in a first contact region to the light emitting device,
light input coupler, lightguide, housing, second region of the low
contact area cover, or thermal transfer element by one or more
methods selected from the group: sewing (or threading or feeding a
fiber, wire, or thread) the low contact area cover to the
lightguide, light mixing region, or other component, welding
(sonic, laser, thermo-mechanically, etc.) the low contact area
cover to one or more components, adhering (epoxy, glue, pressure
sensitive adhesive, etc.) the low contact area cover to one or more
components, fastening the low contact area cover to one or more
components. In a further embodiment, the fastening mechanism is
selected from the group: a batten, button, clamp, clasp, clip,
clutch (pin fastener), flange, grommet, anchor, nail, pin, peg,
clevis pin, cotter pin, linchpin, R-clip, retaining ring, circlip
retaining ring, e-ring retaining ring, rivet, screw anchor, snap,
staple, stitch, strap, tack, threaded fastener, captive threaded
fasteners (nut, screw, stud, threaded insert, threaded rod), tie,
toggle, hook-and-loop strips, wedge anchor, and zipper.
[0285] In another embodiment, the physical coupling mechanism
maintains the flexibility of at least selected from the group:
light emitting device, lightguide and coupling lightguides. In a
further embodiment, the total surface area of the physical coupling
mechanism in contact with at least one selected from the group: low
contact area cover, coupling lightguides, lightguide region, light
mixing region, and light emitting device is less than one selected
from the group: 70%, 50%, 30%, 10%, 5%, and 1%. In another
embodiment, the total percentage of the cross sectional area of the
layers comprising light propagating under total internal reflection
comprising the largest component of the low contact area cover
physical coupling mechanism in a first direction perpendicular to
the optical axis of the light within the coupling lightguides,
light mixing region or lightguide region relative to the
cross-sectional area in the first direction is less than one
selected from the group: 10%, 5%, 1%, 0.5%, 0.1%, and 0.05%. For
example, in one embodiment, the low contact area cover is a
flexible transparent polyurethane film with a surface comprising a
regular two-dimensional array of embossed hemispheres disposed
adjacent and wrapping around the stack of coupling lightguides and
is physically coupled to the light mixing region of the lightguide
comprising a 25 micron thick core layer by threading the film to
the light mixing region using a transparent nylon fiber with a
diameter less than 25 microns into 25 micron holes at 1 centimeter
intervals. In this example, the largest component of the physical
coupling mechanism is the holes in the core region which can
scatter light out of the lightguide. Therefore, the aforementioned
cross sectional area of the physical coupling mechanism (the holes
in the core layer) is 0.25% of the cross sectional area of the core
layer. In another embodiment, the fiber or material threaded
through the holes in one or more components comprises at least one
selected from the group: polymer fiber, polyester fiber, rubber
fiber, cable, wire (such as a thin steel wire), aluminum wire, and
nylon fiber such as used in fishing line. In a further embodiment,
the diameter of the fiber or material threaded through the holes is
less than one selected from the group: 500 microns, 300 microns,
200 microns, 100 microns, 50 microns, 25 microns, and 10 microns.
In another embodiment, the fiber or threaded material is
substantially transparent or translucent.
[0286] In another embodiment, the physical coupling mechanism for
the low contact area cover comprises holes within lightguide
through which an adhesive, epoxy or other adhering material is
deposited which bonds to the low contact area cover, in another
embodiment, the adhesive, epoxy, or other adhering material bonds
to the low contact area cover and at least one selected from the
group: core region, cladding region, and lightguide. In another
embodiment, the adhesive material has a refractive index greater
than 1.48 and reduces the scatter out of the lightguide from the
hole region over using an air gap or an air gap with a fiber,
thread, or wire through the hole. In a further embodiment, an
adhesive is applied as a coating on the fiber (which may be UV
activated, cured, etc. after threading, for example) or an adhesive
is applied to the fiber in the region of the hole such that the
adhesive wicks into the hole to provide reduced scattering by at
least one selected from the group: optically coupling the inner
surfaces of the hole, and optically coupling the fiber to the inner
surfaces of the hole.
[0287] The physical coupling mechanism in one embodiment may be
used to physically couple together one or more elements selected
from the group: film-based lightguide, low contact area cover film,
housing, relative position maintaining element, light redirecting
element or film, diffuser film, collimation film, light extracting
film, protective film, touchscreen film, thermal transfer element,
and other film or component within the light emitting device.
[0288] Lightguide Configuration and Properties
[0289] The use of plastic film with thickness less than 0.5 mm for
edge lit lightguides can hold many advantages over using plastic
plate or sheets. A flexible film may be able to be shaped to
surfaces, be folded up for storage, change shape as needed, or wave
in the air. Another advantage may be lower cost. The reduction in
thickness helps reduce the cost for material, fabrication, storage
and shipping for a lightguide of a given width and length. Another
reason may be that the decreased thickness makes it able to be
added to surfaces without appreciable change in the surface's
shape, thickness and or appearance. For example, it can be added to
the surface of a window easily without changing the look of the
window. Another advantage may be that the film or lightguide can be
rolled up. This helps in transportability, can hold some
functionality, and may be particularly useful for hand-held devices
where a roll-out screen is used. A fifth reason is that the film
can weigh less, which again makes it easier to handle and
transport. A sixth reason may be that film is commonly extruded in
large rolls so larger edge-lit signage can be produced. Finally, a
seventh reason may be that there are many companies set up to coat,
cut, laminate and manipulate film since film is useful for many
other industries. Plastic films are made by blown or cast-extrusion
in widths up to 6.096 meters or longer and in rolls thousands of
meters long. Co-extrusion of different materials from two to 100
layers can be achieved with special extrusion dies.
Thickness of the Film or Lightguide
[0290] In one embodiment, the thickness of the film, lightguide or
lightguide region is within a range of 0.005 mm to 0.5 mm. In
another embodiment, the thickness of the film or lightguide is
within a range of 0.025 millimeters to 0.5 millimeters. In a
further embodiment, the thickness of the film, lightguide or
lightguide region is within a range of 0.050 millimeters to 0.175
millimeters. In one embodiment, the thickness of the film,
lightguide or lightguide region is less than 0.2 millimeters or
less than 0.5 millimeters. In one embodiment, the average thickness
of the lightguide or core region is less than one selected from the
group: 150 microns, 100 microns, 60 microns, 30 microns, 20
microns, 10 microns, 6 microns, and 4 microns. In one embodiment,
at least one selected from the group: thickness, largest thickness,
average thickness, greater than 90% of the entire thickness of one
or more selected from the group: film, lightguide, and lightguide
region is less than 0.2 millimeters. In another embodiment, the
size to thickness ratio, defined as the largest dimension of the
light emitting region in the plane of the light emitting region
divided by the average thickness within the light emitting region
is greater than one selected from the group: 100; 500; 1,000;
3,000; 5,000; 10,000; 15,000; 20,000; 30,000; and 50,000.
Optical Properties of the Lightguide or Light Transmitting
Material
[0291] With regards to the optical properties of lightguides or
light transmitting materials for embodiments, the optical
properties specified herein may be general properties of the
lightguide, the core, the cladding, or a combination thereof or
they may correspond to a specific region (such as a light emitting
region, light mixing region, or light extracting region), surface
(light input surface, diffuse surface, flat surface), and direction
(such as measured normal to the surface or measured in the
direction of light propagation through the lightguide). In one
embodiment, the average luminous transmittance of the lightguide
measured within at least one selected from the group: light
emitting region, light mixing region, and lightguide according to
ASTM D1003 with a BYK Gardner haze meter is greater than one
selected from the group: 70%, 80%, 88%, 92%, 94%, 96%, 98%, and
99%. In another embodiment, the average luminous transmittance of
the lightguide measured within the major light emitting area (the
area comprising greater than 80% of the total light emitted from
the lightguide) according to ASTM D1003 with a BYK Gardner haze
meter is greater than one selected from the group: 70%, 80%, 88%,
92%, 94%, 96%, 98%, and 99%.
[0292] In another embodiment, the average haze of the lightguide
measured within at least one selected from the group: light
emitting region, light mixing region, and lightguide measured with
a BYK Gardner haze meter is less than one selected from the group:
70%, 60%, 50%, 40%, 30%, 20%, 10%, 5% and 3%. In another
embodiment, the average clarity of the lightguide measured within
at least one selected from the group: light emitting region, light
mixing region, and lightguide according to the measurement
procedure associated with ASTM D1003 with a BYK Gardner haze meter
is greater than one selected from the group: 70%, 80%, 88%, 92%,
94%, 96%, 98%, and 99%.
[0293] In a further embodiment, the diffuse reflectance of the
lightguide measured within at least one selected from the group:
light emitting region, light mixing region, and lightguide using a
Minolta CM-508d spectrophotometer is less than one selected from
the group: 30%, 20%, 10%, 7%, 5%, and 2% with the spectral
component included or with the spectral component excluded when
placed above a light absorbing 6''.times.6''.times.6'' box
comprising Light Absorbing Black-Out Material from Edmund Optics on
the inner walls. In another embodiment, the diffuse reflectance of
the lightguide measured within the major light emitting area (the
area comprising greater than 80% of the total light emitted from
the lightguide) using a Minolta CM-508d spectrophotometer is less
than one selected from the group: 30%, 20%, 10%, 7%, 5%, and 2%
with the spectral component included or with the spectral component
excluded when placed above a light absorbing
6''.times.6''.times.6'' box comprising Light Absorbing Black-Out
Material from Edmund Optics Inc. on the inner walls.
[0294] In another embodiment, the average clarity of the lightguide
measured within at least one selected from the group: light
emitting region, light mixing region, and lightguide measured with
a BYK Gardner haze meter is greater than one selected from the
group: 70%, 80%, 88%, 92%, 94%, 96%, 98%, and 99%.
[0295] Factors which can determine the transmission of light
through the film (in the thickness direction) include inherent
material absorption, refractive index (light loss due to Fresnel
reflections), scattering (refraction, reflection, or diffraction)
from particles or features within the volume or on a surface or
interface (size, shape, spacing, total number of particles or
density in two orthogonal directions parallel to the film plane and
the plane orthogonal to the
absorption/scattering/reflection/refraction due to other materials
(additional layers, claddings, adhesives, etc.), anti-reflection
coatings, surface relief features.
[0296] In one embodiment, the use of a thin film for the lightguide
permits the reduction in size of light extraction features because
more waveguide modes will reach the light extraction feature when
the thickness of the film is reduced. In a thin lightguide, the
overlap of modes is increased when the thickness of the waveguide
is reduced.
[0297] In one embodiment, the film-based lightguide has a graded
refractive index profile in the thickness direction. In another
embodiment, the thickness of the lightguide region or lightguide is
less than 10 microns and the lightguide is a single mode
lightguide.
[0298] In one embodiment, the light transmitting material used in
at least one selected from the group: coupling lightguide,
lightguide, lightguide region, optical element, optical film, core
layer, cladding layer, and optical adhesive has an optical
absorption (dB/km) less than one selected from the group: 50, 100,
200, 300, 400, and 500 dB/km for a wavelength range of interest.
The optical absorption value may be for all of the wavelengths
throughout the range of interest or an average value throughout the
wavelengths of interest. The wavelength range of interest for high
transmission through the light transmitting material may cover the
light source output spectrum, the light emitting device output
spectrum, optical functionality requirements (IR transmission for
cameras, motion detectors, etc., for example), or some combination
thereof. The wavelength range of interest may be a wavelength range
selected from the group: 400 nm-700 nm, 300 nm-800 nm, 300 nm-1200
nm, 300 nm-350 nm, 300-450 nm, 350 nm-400 nm, 400 nm-450 nm, 450
nm-490 nm, 490 nm-560 nm, 500 nm-550 nm, 550 nm-600 nm, 600 nm-650
nm, 635 nm-700 nm, 650 nm-700 nm, 700 nm-750 nm, 750 nm-800 nm, and
800 nm-1200 nm.
[0299] Collimated tight propagating through light transmitting
material may be reduced in intensity after passing through the
material due to scattering (scattering loss coefficient),
absorption (absorption coefficient), or a combination of scattering
and absorption (attenuation coefficient). In one embodiment, the
core material of the lightguide has an average absorption
coefficient for collimated light less than one selected from the
group: 0.03 cm.sup.-1, 0.02 cm.sup.-1, 0.01 cm.sup.-1, and 0.005
cm.sup.-1 over the visible wavelength spectrum from 400 nanometers
to 700 nanometers. In another embodiment, the core material of the
lightguide has an average scattering loss coefficient for
collimated light less than one selected from the group: 0.03
cm.sup.-1, 0.02 cm.sup.-1, 0.01 cm.sup.-1, and 0.005 cm.sup.-1 over
the visible wavelength spectrum from 400 nanometers to 700
nanometers. In one embodiment, the core material of the lightguide
has an average attenuation coefficient for collimated light less
than one selected from the group: 0.03 cm.sup.-1, 0.02 cm.sup.-1,
0.01 cm.sup.-1, and 0.005 cm.sup.-1 over the visible wavelength
spectrum from 400 nanometers to 700 nanometers. In another
embodiment, the lightguide is disposed to receive infrared light
and the average of at least one selected from the group: absorption
coefficient, scattering loss coefficient, and attenuation
coefficient of the core layer or cladding layer for collimated
light is less than one selected from the group: 0.03 cm.sup.-1,
0.02 cm.sup.-1, 0.01 cm.sup.-1, and 0.005 cm.sup.-1 over the
wavelength spectrum from 700 nanometers to 900 nanometers.
[0300] In one embodiment, the lightguide has a low absorption in
the UV and blue region and the lightguide further comprises a
phosphor film or wavelength conversion element. By using a blue or
UV light source and a wavelength conversion element near the output
surface of the lightguide for generation of white light, the light
transmitting material can be optimized for very high blue or UV
light transmission. This can increase the range of materials
suitable for lightguides to include those that have high absorption
coefficients in the green and red wavelength regions for
example.
[0301] In another embodiment, the lightguide is the substrate for a
display technology. Various high performance films are known in the
display industry as having sufficient mechanical and optical
properties. These include, but are not limited to polycarbonate,
PET, PMMA, PEN. COC, PSU, PFA, FIT, and films made from blends and
multilayer components. In one embodiment, the light extraction
feature is formed in a lightguide region of a film before or after
the film is utilized as a substrate for the production or use as a
substrate for a display such as an OLED display, MEMs based
display, polymer film-based display, bi-stable display,
electrophoretic display, electrochromic display, electro-optical
display, passive matrix display, or other display that can be
produced using polymer substrates.
Refractive Index of the Light Transmitting Material
[0302] In one embodiment, the core material of the lightguide has a
high refractive index and the cladding material has a low
refractive index. In one embodiment, the core is formed from a
material with a refractive index (n.sub.D) greater than one
selected from the group: 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0,
2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, and 3.0. In another
embodiment, the refractive index (n.sub.D) of the cladding material
is less than one selected from the group: 1.1, 1.2, 1.3, 1.4, 1.5,
1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, and 2.5.
[0303] The core or the cladding or other light transmitting
material used within an embodiment may be a thermoplastic,
thermoset, rubber, polymer, silicone or other light transmitting
material. Optical products can be prepared from high index of
refraction materials, including monomers such as high index of
refraction (meth)acrylate monomers, halogenated monomers, and other
such high index of refraction monomers as are known in the art.
High refractive index materials such as these and others are
disclosed, for example, in U.S. Pat. Nos. 4,568,445; 4,721,377;
4,812,032; 5,424,339; 5,183,917; 6,541,591; 7,491,441; 7,297,810,
6,355,754, 7,682,710; 7,642,335; 7,632,904; 7,407,992; 7,375,178;
6,117,530; 5,777,433; 6,533,959; 6,541,591; 7,038,745 and U.S.
patent application Ser. Nos. 11/866,521; 12/165,765; 12/307,555;
and 11/556,432. High refractive index pressure sensitive adhesives
such as those disclosed in U.S. patent application Ser. No.
12/608,019 may also be used as a core layer or layer component.
[0304] Low refractive index materials include sol gels,
fluoropolymers, fluorinated sol-gels, PMP, and other materials such
fluoropolyether urethanes such as those disclosed in U.S. Pat. No.
7,575,847, and other low refractive index material such as those
disclosed in U.S. patent application Ser. Nos. 11/972,034;
12/559,690; 12/294,694; 10/098,813; 11/026,614; and U.S. Pat. Nos.
7,374,812; 7,709,551; 7,625,984; 7,164,536; 5,594,830 and
7,419,707.
[0305] Materials such a nanoparticles (titanium dioxide, and other
oxides for example), blends, alloys, doping, sol gel, and other
techniques may be used to increase or decrease the refractive index
of a material.
[0306] In another embodiment the refractive index or location of a
region of lightguide or lightguide region changes in response to
environmental changes or controlled changes. These changes can
include electrical current, electromagnetic field, magnetic field,
temperature, pressure, chemical reaction, movement of particles or
materials (such as electrophoresis or electrowetting), optical
irradiation, orientation of the object with respect to
gravitational field, MEMS devices, MOEMS devices, and other
techniques for changing mechanical, electrical, optical or physical
properties such as those known in the of smart materials. In one
embodiment, the light extraction feature couples more or less light
out of the lightguide in response to an applied voltage or
electromagnetic field. In one embodiment, the light emitting device
comprises a lightguide wherein properties of the lightguide (such
as the position of the lightguide) which change to couple more or
less light out of a lightguide such as those incorporated in MEMs
type displays and devices as disclosed in U.S. patent application
Ser. Nos. 12/511,693; 12/606,675; 12/221,606; 12/258,206;
12/483,062; 12/221,193; 11/975,411 11/975,398; 10/31/2003;
10/699,397 and U.S. Pat. Nos. 7,586,560; 7,535,611; 6,680,792;
7,556,917; 7,532,377; and 7,297,471.
Edges of the Lightguide
[0307] In one embodiment, the edges of the lightguide or lightguide
region are coated, bonded to or disposed adjacent to a specularly
reflecting material, partially diffusely reflecting material, or
diffuse reflecting material. In one embodiment, the lightguide
edges are coated with a specularly reflecting ink comprising
nano-sized or micron-sized particles or flakes which reflect the
light substantially specularly. In another embodiment, a light
reflecting element (such as a specularly reflecting multi-layer
polymer film with high reflectivity) is disposed near the
lightguide edge and is disposed to receive light from the edge and
reflect it and direct it back into the lightguide. In another
embodiment, the lightguide edges are rounded and the percentage of
light diffracted from the edge is reduced. One method of achieving
rounded edges is by using a laser to cut the lightguide from a film
and achieve edge rounding through control of the processing
parameters (speed of cut, frequency of cut, laser power, etc.). In
another embodiment, the edges of the lightguide are tapered, angled
serrated, or otherwise cut or formed such that light from a light
source propagating within the coupling lightguide reflects from the
edge such that it is directed into an angle closer to the optical
axis of the light source, toward a folded region, toward a bent
region, toward a lightguide, toward a lightguide region, or toward
the optical axis of the light emitting device. In a further
embodiment, two or more light sources are disposed to each couple
light into two or more coupling lightguides comprising light
re-directing regions for each of the two or more light sources that
comprise first and second reflective surfaces which direct a
portion of light from the light source into an angle closer to the
optical axis of the light source, toward a folded or bent region,
toward a lightguide region, toward a lightguide region, or toward
the optical axis of the light emitting device.
Surfaces of the Lightguide
[0308] In one embodiment, at least one surface of the lightguide or
lightguide region is coated, bonded to or disposed adjacent to a
specularly reflecting material, partially diffusely reflecting
material, or diffuse reflecting material. In one embodiment, at
least on lightguide surface is coated with a specularly reflecting
ink comprising nano-sized or micron-sized particles or flakes which
reflect the light substantially specularly. In another embodiment,
a light reflecting element (such as a specularly reflecting
multi-layer polymer film with high reflectivity) is disposed near
the lightguide surface opposite the light emitting surface and is
disposed to receive light from the surface and reflect it and
direct it back into the lightguide. In another embodiment, the
outer surface of at least one lightguide or component coupled to
the lightguide comprises a microstructure to reduce the appearance
of fingerprints. Such microstructures are known in the art of
hardcoatings for displays and examples are disclosed in U.S. patent
application Ser. No. 12/537,930.
Shape of the Lightguide
[0309] In one embodiment, at least a portion of the lightguide
shape or lightguide surface is at least one selected from the
group: substantially planar, curved, cylindrical, a formed shape
from a substantially planar film, spherical, partially spherical,
angled, twisted, rounded, have a quadric surface, spheroid, cuboid,
parallelepiped, triangular prism, rectangular prism, ellipsoid,
ovoid, cone pyramid, tapered triangular prism and other known
geometrical solids or shapes. In one embodiment, the lightguide is
a film which has been formed into a shape by thermoforming or other
forming technique. In another embodiment, the film or region of the
film is tapered in at least one direction. In a further embodiment,
a light emitting device comprises a plurality of lightguides and a
plurality of light sources physically couple or arranged together
(such as tiled in a 1.times.2 array for example). In another
embodiment, the lightguide region of the film is substantially in
the shape of one selected from the group: rectangular, square,
circle, doughnut shaped (elliptical with a hole in the inner
region), elliptical, linear strip, tube (with a circular,
rectangular, polygonal, or other shaped cross-section).
[0310] In one embodiment, a light emitting device comprises a
lightguide formed from a film into a hollow cylindrical tube
comprises coupling lightguide strips branching from the film on a
short edge toward the inner portion of the cylinder. In another
embodiment, a light emitting device comprises a film lightguide
with coupling lightguides cut into the film so that they remain
coupled to the lightguide region and the central strip is not
optically coupled to the lightguide and provides a spine with
increased stiffness in at least one direction near the central
strip region or lightguide region near the strip. In a further
embodiment, a light emitting device comprises lightguides with
light input couplers arranged such that the light source is
disposed in the central region of the edge of the lightguide and
that the light input coupler (or a component thereof) does not
extend past the edge and enables the lightguides to be tiled in at
least one of a 1.times.2, 2.times.2, 2.times.3, 3.times.3 or larger
array. In another embodiment, a light emitting device comprises
light emitting lightguides wherein the separation between the
lightguides in at least one direction along the light emitting
surface is less than one selected from the group: 10 mm, 5 mm, 3
mm, 2 mm, 1 mm, and 0.5 mm.
[0311] In another embodiment, the lightguide comprises single fold
or bend near an edge of the lightguide such that the lightguide
folds under or over itself. In this embodiment, light which would
ordinarily be lost at the edge of a lightguide may be further
extracted from the lightguide after the fold or bend to increase
the optical efficiency of the lightguide or device. In another
embodiment, the light extraction features on the lightguide
disposed in the optical path of the light within the lightguide
after the fold or bend provide light extraction features that
increase at least one selected from the group: the luminance,
luminance uniformity, color uniformity, optical efficiency, and
image or logo clarity or resolution.
Edges Fold Around Back onto the Lightguide
[0312] In one embodiment, at least one edge region of one or more
selected from the group: lightguide, lightguide region, and
coupling lightguides folds or bends back upon itself and is
optically coupled to the lightguide, lightguide region or coupling
lightguide such that a portion entering the edge region is coupled
back into the lightguide, lightguide region, or coupling lightguide
in a direction away from the edge region. The edge regions may be
adhered using an adhesive such as PSA or other adhesive, thermally
bonded, or otherwise optically coupled back onto the lightguide,
lightguide region, or coupling lightguide. In one embodiment,
folding the edge regions of the lightguide redirects light that
would normally exit the edge of the film back into the lightguide,
and the optical efficiency of the system is increased.
[0313] In another embodiment, the thickness of the lightguide,
lightguide region, or coupling lightguide is thinner in the region
near an edge than the average thickness of the lightguide in the
light emitting region or lightguide region. In another embodiment,
the thickness of the lightguide, lightguide region, or coupling
lightguide is less than one selected from the group: 90%, 80%, 70%,
60%, 50%, 40%, 30%, 20%, 10%, and 5% of the average thickness of
the lightguide in the light emitting region or lightguide
region.
[0314] In one embodiment, the thickness of the lightguide,
lightguide region, or coupling lightguide is tapered in the region
near an edge. In one embodiment, tapering the thickness in the
region near edge permits more light to couple back into the
lightguide when it is optically coupled to the surface of the
lightguide or lightguide region.
[0315] In one embodiment, the light emitting device has an optical
efficiency, defined as the luminous flux of the light exiting the
light emitting device in the light emitting region divided by the
luminous flux of the light exiting the light source disposed to
direct light into the input coupler, greater than one selected from
the group: 50%, 60%, 70%, 80%, and 90%.
[0316] In another embodiment, the edge region of a lightguide not
disposed to receive light directly from a light source or light
input coupler is formed or coupled into a light output coupler
comprising coupling lightguides which are folded or bent to create
a light output surface. In another embodiment, the light output
surface is optically coupled to or disposed proximal to a light
input surface of a light input coupler for the same lightguide or
film or a second lightguide or film. In this embodiment, the light
reaching the edge of a lightguide may be coupled into coupling
strips which are folded and bent to direct light back into the
lightguide and recycle the light.
Lightguide Material
[0317] In one embodiment, a light emitting device comprises a
lightguide or lightguide region formed from at least one light
transmitting material. In one embodiment, the lightguide is a film
comprising at least one core region and at least one cladding
region, each comprising at least one light transmitting material.
In one embodiment, the core material is substantially flexible
(such as a rubber or adhesive) and the cladding material supports
and provides at least one selected from the group: increased
flexural modulus, increased impact strength, increased tear
resistance, and increased scratch resistance for the combined
element. In another embodiment, the cladding material is
substantially flexible (such as a rubber or adhesive) and the core
material supports and provides at least one selected from the
group: increased flexural modulus, increased impact strength,
increased tear resistance, and increased scratch resistance for the
combined element.
[0318] The light transmitting material used within an embodiment
may be a thermoplastic, thermoset, rubber; polymer, high
transmission silicone, glass, composite; alloy, blend, silicone,
other light transmitting material, or a combination thereof.
[0319] In one embodiment, a component or region of the light
emitting device comprises a light transmitting material selected
from the group: cellulose derivatives (e.g., cellulose ethers such
as ethylcellulose and cyanoethylcellulose, cellulose esters such as
cellulose acetate), acrylic resins, styrenic resins (e.g.,
polystyrene), polyvinyl-series resins(e.g., poly(vinyl ester) such
as poly(vinyl acetate), polyvinyl halide) such as poly(vinyl
chloride), polyvinyl alkyl ethers or polyether-series resins such
as poly(vinyl methyl ether), poly(vinyl isobutyl ether) and
poly(vinyl t-butyl ether)], polycarbonate-series resins (e.g.,
aromatic polycarbonates such as bisphenol A-type polycarbonate),
polyester-series resins(e.g., homopolyesters, for example,
polyalkylene terephthalates such as polyethylene terephthalate and
polybutylene terephthalate, polyalkylene naphthalates corresponding
to the polyalkylene terephthalates; copolyesters containing an
alkylene terephthalate and/or alkylene naphthalate as a main
component; homopolymers of lactones such as polycaprolactone),
polyamide-series resin (e.g., nylon 6, nylon 66, nylon 610),
urethane-series resins (e.g., thermoplastic polyurethane resins),
copolymers of monomers forming the above resins [e.g., styrenic
copolymers such as methyl methacrylate-styrene copolymer (MS
resin), acrylonitrile-styrene copolymer (AS resin),
styrene-(meth)acrylic acid copolymer, styrene-maleic anhydride
copolymer and styrene-butadiene copolymer, vinyl acetate-vinyl
chloride copolymer, vinyl alkyl ether-maleic anhydride copolymer].
Incidentally, the copolymer may be whichever of a random copolymer,
a block copolymer, or a graft copolymer.
Lightguide Material Comprises Glass
[0320] In one embodiment, the coupling lightguides comprise a core
material comprising an glass material. In one embodiment, the glass
material is one selected from the group: fused silica, ultraviolet
grade fused silica (such as JGSI by Dayoptics Inc., Suprasil.RTM. 1
and 2 by Heraeus Quartz America, LLC., Spectrosil.RTM. A and B by
Saint-Ciobain Quartz PLC, and Corning 7940 by Corning Incorporated,
Dynasil.RTM. Synthetic Fused Silica 1100 and 4100 by Dynasil
Corporation), optical grade fused quartz, full spectrum fused
silica, borosilicate glass, crown glass, and aluminoborosilicate
glass.
[0321] In another embodiment, the core material comprises a glass
which is coated, or has an organic material applied to at least one
selected from the group: edge, top surface, and bottom surface. In
one embodiment, the coating on the glass functions to at least one
selected from the group: provide a cladding region, increase impact
resistance, and provide increased flexibility. In another
embodiment, the coupling lightguides comprising glass, a polymeric
material, or a rubber material are heated to a temperature above
their glass transition temperature or VICAT softening point before
folding in a first direction.
Multilayer Lightguide
[0322] In one embodiment, the lightguide comprises at least two
layers or coatings. In another embodiment, the layers or coatings
function as at least one selected from the group: a core layer, a
cladding layer, a tie layer (to promote adhesion between two other
layers), a layer to increase flexural strength, a layer to increase
the impact strength (such as Izod, Charpy, Gardner, for example),
and a carrier layer. In a further embodiment, at least one layer or
coating comprises a microstructure, surface relief pattern, light
extraction features, lenses, or other non-flat surface features
which redirect a portion of incident light from within the
lightguide to an angle whereupon it escapes the lightguide in the
region near the feature. For example, the carrier film may be a
silicone film with embossed light extraction features disposed to
receive a thermoset polycarbonate resin. In another embodiment, the
carrier film is removed from contact with the core material in at
least one region. For example, the carrier film may be an embossed
FEP film and a thermoset methacrylate based resin is coated upon
the film and cured by heat, light, other radiation, or a
combination thereof. In another embodiment, the core material
comprises a methacrylate material and the cladding comprises a
silicone material. In another embodiment, a cladding material is
coated onto a carrier film and subsequently, a core layer material,
such as a silicone, a PC, or a PMMA based material, is coated or
extruded onto the cladding material. In one embodiment, the
cladding layer is too thin to support itself in a coating line and
therefore a carrier film is used. The coating may have surface
relief properties one the side opposite the carrier film, for
example.
[0323] In one embodiment, the lightguide comprises a core material
disposed between two cladding regions wherein the core region
comprises a polymethyl methacrylate, polystyrene, or other
amorphous polymer and the lightguide is bent at a first radius of
curvature and the core region and cladding region are not fractured
in the bend region, wherein the same core region comprising the
same polymethyl methacrylate without the cladding regions or layers
fractures more than 50% of the time when bent a the first radius of
curvature. In another embodiment, a lightguide comprises
substantially ductile polymer materials disposed on both sides of a
substantially brittle material of a first thickness such as PMMA or
polystyrene without impact modifiers and the polymer fracture
toughness or the ASTM D4812 un-notched Izod impact strength of the
lightguide is greater than a single layer of the brittle material
of a first thickness.
Core Region Comprising a Thermoset Material
[0324] In one embodiment, a thermoset material is coated onto a
thermoplastic film wherein the thermoset material is the core
material and the cladding material is the thermoplastic film or
material. In another embodiment, a first thermoset material is
coated onto a film comprising a second thermoset material wherein
the first thermoset material is the core material and the cladding
material is the second thermoset plastic.
[0325] In one embodiment, an epoxy resin that has generally been
used as a molding material may be used as the epoxy resin (A).
Examples include epoxidation products of novolac resins derived
from phenols and aldehydes, such as phenol novolac epoxy resins and
ortho-cresol novolac epoxy resins; diglycidyl ethers of bisphenol
A, bisphenol F, bisphenol S, alkyl-substituted bisphenol, or the
like; glycidylamine epoxy resins obtained by the reaction of a
polyamine such as diaminodiphenylmethane and isocyanuric acid with
epichlorohydrin; linear aliphatic epoxy resins obtained by
oxidation of olefin bonds with a peracid such as peracetic acid;
and alicyclic epoxy resins. Any two or more of these resins may be
used in combination. Examples of thermoset resins further include
bisphenol A epoxy resins, bisphenol F epoxy resins, bisphenol S
epoxy resins, diglycidyl isocyanurate, and triglycidyl
isocyanurate, P(MMA-d8) material, fluorinated resin, deuterated
polymer, poly(fluoroalkyl-MA), poly(deuterated fluoroalkyl-MA),
trideutero hexafluorobutyl-pentadeutero methacylate, and triazine
derived epoxy resin.
[0326] In another embodiment, the thermosetting resin is a
thermosetting silicone resin. In a father embodiment, the
thermosetting silicone resin composition comprises a condensation
reactable substituent group-containing silicon compound and an
addition reactable substituent group-containing silicon compound.
In another embodiment, the thermosetting silicone resin composition
comprises a dual-end silanol type silicone oil as the condensation
reactable substituent group-containing silicon compound; an alkenyl
group-containing silicon compound; an organohydrogensiloxane as the
addition reactable substituent group-containing silicon compound; a
condensation catalyst; and a hydrosilylation catalyst. In one
embodiment, the thermosetting resin is a methylphenyl dimethyl
copolymer or comprises a silicone based material such as disclosed
in U.S. Pat. No. 7,551,830. In another embodiment, the
thermosetting resin comprises a polydiorganosiloxane having an
average, per molecule, of at least two aliphatically unsaturated
organic groups and at least one aromatic group; (B) a branched
polyorganosiloxane having an average, per molecule, of at least one
aliphatically unsaturated organic group and at least one aromatic
group; (C) a polyorganohydrogensiloxane having an average per
molecule of at least two silicon-bonded hydrogen atoms and at least
one aromatic group, (D) a hydrosilylation catalyst, and (E)
silylated acetylenic inhibitor. In another embodiment, the
thermosetting comprises a silicone, polysiloxane, or silsesquioxane
material such as disclosed in U.S. patent application Ser. Nos.
12/085,422 and 11/884,612.
[0327] In a further embodiment, the thermosetting material
comprises: a liquid crystalline thermoset oligomer containing at
least aromatic or alicyclic structural unit with a kink structure
in the backbone and having one or two thermally crosslinkable
reactive groups introduced at one or both ends of the backbone;
either a crosslinking agent having thermally crosslinkable reactive
groups at both ends thereof or an epoxy compound or both; and an
organic solvent. In a further embodiment, the thermosetting
composition comprises at least one selected from the group: an
aluminosiloxane, a silicone oil containing silanol groups at both
ends, an epoxy silicone, and a silicone elastomer. In this
thermosetting composition, it is considered that each of hydroxyl
groups of the aluminosiloxane and/or the silicone oil containing
silanol groups at both ends, and a highly reactive epoxy group of
the epoxy silicone are reacted and cross-linked, at the same time
the silicone elastomer is cross-linked by a hydrosilylation
reaction therewith. In another embodiment, the thermoset is a
photopolymerizable composition. In another embodiment, the
photopolymerizable composition comprises: a silicon-containing
resin comprising silicon-bonded hydrogen and aliphatic
unsaturation, a first metal-containing catalyst that may be
activated by actinic radiation, and a second metal-containing
catalyst that may be activated by heat but not the actinic
radiation.
[0328] In another embodiment, the thermosetting resin comprises a
silsesquioxane derivative or a Q-containing silicone. In another
embodiment, the thermosetting resin is a resin with substantially
high transmission such as those disclosed in U.S. patent
application Ser. Nos. 12/679,749, 12/597,531, 12/489,881,
12/637,359, 12/637,359, 12/549,956, 12/759,293, 12/553,227,
11/137,358, 11/391,021, and 11/551,323.
[0329] In a further embodiment, the lightguide comprises a
thermoset resin that is coated onto an element of the light
emitting device (such as a carrier film with a coating, an optical
film, the rear polarizer in an LCD, a brightness enhancing film, a
thermal transfer element such as a thin sheet comprising aluminum,
or a white reflector film) and subsequently cured or thermoset.
Lightguide Material with Adhesive Properties
[0330] In another embodiment, the lightguide comprises a material
with at least one selected from the group: chemical adhesion,
dispersive adhesion, electrostatic adhesion, diffusive adhesion,
and mechanical adhesion to at least one element of the light
emitting device (such as a carrier film with a coating, an optical
film, the rear polarizer in an LCD, a brightness enhancing film,
another region of the lightguide, a coupling lightguide, a thermal
transfer element such as a thin sheet comprising aluminum, or a
white reflector film). In a further embodiment, at least one of the
core material or cladding material of the lightguide is an adhesive
material. In a further embodiment, at least one selected from the
group: core material, cladding material, and material disposed on a
cladding material of the lightguide is at least one selected from
the group: pressure sensitive adhesive, contact adhesive, hot
adhesive, drying adhesive, multi-part reactive adhesive, one-part
reactive adhesive, natural adhesive, and synthetic adhesive. In a
further embodiment, the first core material of a first coupling
lightguide is adhered to the second core material of a second
coupling lightguide due to the adhesion properties of the first
core material, second core material, or a combination thereof. In
one embodiment, the core layer is an adhesive and is coated onto at
least one selected from the group: cladding layer, removable
support layer, protective film, second adhesive layer, polymer
film, metal film, second core layer, low contact area cover, and
planarization layer. In another embodiment, the cladding material
of a first coupling lightguide is adhered to the core material of a
second coupling lightguide due to the adhesion properties of the
cladding material. In another embodiment, the first cladding
material of a first coupling lightguide is adhered to the second
cladding material of a second coupling lightguide due to the
adhesion properties of the first cladding material, second cladding
material, or a combination thereof. In another embodiment, the
cladding material or core material has adhesive properties and has
an ASTM D3330 Peel strength greater than one selected from the
group: 929, 17.858, 35.716, 53.574, 71.432, 89, 29, 107.148,
125.006, 142.864, 160.722, 178.580 kilograms per meter of bond
width when adhered to an element of the light emitting device, such
as for example without limitation, a cladding layer, a core layer,
a low contact area cover, a circuit board, or a housing.
[0331] In another embodiment, a tie layer, primer, or coating is
used to promote adhesion between at least one selected from the
group: core material and cladding material, lightguide and housing,
core material and element of the light emitting device, cladding
material and element of the light emitting device. In one
embodiment, the tie layer or coating comprises a dimethyl silicone
or variant thereof and a solvent, hu another embodiment, the tie
layer comprises a phenyl based primer such as those used to bridge
phenylsilaxane-based silicones with substrate materials. In another
embodiment, the tie layer comprises a platinum-catalyzed,
addition-cure silicone primer such as those used to bond plastic
film substrates and silicone pressure sensitive adhesives.
[0332] In a further embodiment, at least one region of the core
material or cladding material has adhesive properties and is
optical coupled to a second region of the core or cladding material
such that the ASTM D1003 luminous transmittance of visible light
through the interface is at least one selected from the group: 1%,
2%, 3%, and 4% greater than the transmission through the same two
material at the same region with an air gap disposed between
them.
Outermost Surface of the Film or Lightguide
[0333] In one embodiment, the outermost surface of the film,
lightguide or lightguide region comprises at least one selected
from the group: cladding, surface texture to simulate a soft feel
or match the surface texture of cloth or upholstery, a refractive
element to collimate light from the light extraction features (such
as microlens array), an adhesive layer, a removable backing
material, an anti-reflection coating, an anti-glare surface, and a
rubber surface.
Light Extraction Method
[0334] In one embodiment, at least one of the lightguide,
lightguide region, or light emitting region comprises at least one
light extraction feature or region. In one embodiment, the light
extraction region may be a raised or recessed surface pattern or a
volumetric region. Raised and recessed surface patterns include
scattering material, raised lenses, scattering surfaces, pits,
grooves, surface modulations, microlenses, lenses, diffractive
surface features, holographic surface features, wavelength
conversion materials, holes, edges of layers (such as regions where
the cladding is removed from covering the core layer), pyramid
shapes, prism shapes, and other geometrical shapes with flat
surfaces, curved surfaces, random surfaces, quasi-random surfaces
or a combination thereof. The volumetric scattering regions within
the light extraction region may comprise dispersed phase domains,
voids, absence of other materials or regions (gaps, holes), air
gaps, boundaries between layers and regions, and other refractive
index discontinuities within the volume of the material different
that co-planar layers with parallel interfacial surfaces. In one
embodiment, the light extracting region comprises angled or curved
surface or volumetric light extracting features that redirect a
first redirection percentage of light into an angular range within
5 degrees of the normal to the light emitting surface of the light
emitting device. In another embodiment, the first redirection
percentage is greater than one selected from the group: 5, 10, 20,
30, 40, 50, 60, 70, 80, and 90. In one embodiment, the light
extraction features are light redirecting features, light
extracting regions or light output coupling features.
[0335] In one embodiment, the lightguide or lightguide region
comprises light extraction features in a plurality of regions. In
one embodiment, the lightguide or lightguide region comprises light
extraction features on or within at least one selected from the
group: one outer surface, two outer surfaces, two outer and
opposite surfaces, an outer surface and at least one region
disposed between the two outer surfaces, within two different
volumetric regions substantially within two different volumetric
planes parallel to at least one outer surface or light emitting
surface or plane, and within a plurality of volumetric planes. In
another embodiment, a light emitting device comprises a light
emitting region on the lightguide region of a lightguide comprising
more than one region of light extraction features,
[0336] In another embodiment, one or more light extraction features
are disposed on top of another light extraction feature. For
example, grooved light extraction features could comprise light
scattering hollow microspheres which may increase the amount of
light extracted from the lightguide or which could further scatter
or redirect the light that is extracted by the grooves. More than
one type of light extraction feature may be used on the surface,
within the volume of a lightguide or lightguide region, or a
combination thereof.
[0337] In a further embodiment, the light extraction features are
grooves, indentations, curved, or angled features that redirect a
portion of light incident in a first direction to a second
direction within the same plane through total internal reflection.
In another embodiment, the light extraction features redirect a
first portion of light incident at a first angle into a second
angle greater than the critical angle in a first output plane and
increase the angular full width at half maximum intensity in a
second output plane orthogonal to the first. In a further
embodiment, the light extraction feature is a region comprising a
groove, indentation, curved or angled feature and further comprises
a substantially symmetric or isotropic light scattering region of
material such as dispersed voids, beads, microspheres,
substantially spherical domains, or a collection of randomly shaped
domains wherein the average scattering profile is substantially
symmetric or isotropic. In a further embodiment, the light
extraction feature is a region comprising a groove, indentation,
curved or angled feature and further comprises a substantially
anisotropic or asymmetric light scattering region of material such
as dispersed elongated voids, stretched beads, asymmetrically
shaped ellipsoidal particles, fibers, or a collection of shaped
domains wherein the average scattering is profile is substantially
asymmetric or anisotropic. In one embodiment, the Bidirectional
Scattering Distribution Function (BsDr) of the light extraction
feature is controlled to create a predetermined light output
profile of the light emitting device or light input profile to a
light redirecting element.
[0338] In one embodiment, at least one light extraction feature is
an array, pattern or arrangement of a wavelength conversion
material selected from the group: a fluorophore, phosphor, a
fluorescent dye, an inorganic phosphor, photonic handgap material,
a quantum dot material, a fluorescent protein, a fusion protein, a
fluorophores attached to protein to specific functional groups,
quantum dot fluorophores, small molecule fluorophores, aromatic
fluorophores, conjugated fluorophores, and a fluorescent dye
scintillators, phosphors such as Cadmium sulfide, rare-earth doped
phosphor, and other known wavelength conversion materials.
[0339] In one embodiment, the light extraction feature is a
specularly, diffusive, or a combination thereof reflective
material. For example, the light extraction feature may be a
substantially specularly reflecting ink disposed at an angle (such
as coated onto a groove) or it may be a substantially diffusely
reflective ink such as an ink comprising titanium dioxide particles
within a methacrylate-based binder (white paint). Alternatively,
the light extraction feature may be a partially diffusively
reflecting ink such as an ink with small silver particles (micron
or sub-micron, spherical or non-spherical, plate-like shaped or
non-plate-like shaped, or silver (or aluminum) coated onto flakes)
further comprising titanium dioxide particles. In another
embodiment, the degree of diffusive reflection is controlled to
optimize at least one selected from the group: the angular output
of the device, the degree of collimation of the light output, and
the percentage of light extracted from the region.
[0340] The pattern or arrangement of light extraction features may
vary in size, shape, pitch, location, height, width, depth, shape,
orientation, in the x, y, or z directions. Patterns and formulas or
equations to assist in the determination of the arrangement to
achieve spatial luminance or color uniformity are known in the art
of edge-illuminated backlights. In one embodiment, a light emitting
device comprises a film-based lightguide comprising light
extraction features disposed beneath lenticules wherein the light
extraction features are substantially arranged in the form of
dashed lines beneath the lenticules such that the light extracted
from the line features has a lower angular FHWM intensity after
redirection from the lenticular lens array light redirecting
element and the length of the dashes varies to assist with the
uniformity of light extraction. In another embodiment, the dashed
line pattern of the light extraction features varies in the x and y
directions (where the z direction is the optical axis of the light
emitting device). Similarly, a two-dimensional microlens array film
(close-packed or regular array) or an arrangement of microlenses
may be used as a light redirecting element and the light extraction
features may comprise a regular, irregular, or other arrangement of
circles, ellipsoidal shapes, or other pattern or shape that may
vary in size, shape, or position in the x direction, y direction,
or a combination thereof.
Visibility of Light Extraction Features
[0341] In one embodiment, at least one light extraction region
comprises light extraction features which have a low visibility to
the viewer when the region is not illuminated by light from within
the lightguide (such as when the device is in the off-state or the
particular lightguide in a multi-lightguide device is not
illuminated). In one embodiment, the luminance at a first
measurement angle of at least one selected from the group:
lightguide region, square centimeter measurement area of the light
emitting surface corresponding to light redirected by at least one
light extraction feature, light emitting region, light extraction
feature, and light extracting surface feature or collection of
light extraction features is less than one selected from the group:
0.5 cd/m.sup.2, 1 cd/m.sup.2, 5 cd/m.sup.2, 10 cd/m.sup.2, 50
cd/m.sup.2, and 100 cd/m.sup.2 when exposed to diffuse illuminance
from an integrating sphere of one selected from the group: 10 lux,
50 lux, 75 lux, 100 lux, 200 lux, 300 lux, 400 lux, 500 lux, 750
lux, and 1000 lux when place over a black, light absorbing surface.
Examples of a light absorbing surface include, without limitation,
a black velour cloth material, black anodized aluminum, material
with a diffuse reflectance (specular component included) less than
5%, Light Absorbing Black-Out
[0342] Material from Edmund Optics Inc., and a window to a light
trap box (box with light absorbing black velour lining the walls).
In one embodiment, the first measurement angle for the luminance is
one selected from the group: 0 degrees, 5 degrees, 8 degrees, 10
degrees, 20 degrees, 40 degrees, 0-10 degrees, 0-20 degrees, 0-30
degrees, and 0-40 degrees from the normal to the surface. In one
embodiment, the luminance of the light emitted from a 1 cm.sup.2
measurement area of the light emitting surface corresponding to
light redirected by at least one light extracting feature is less
than 100 cd/m2 when exposed to a diffuse illuminance of 200 lux
from an integrating sphere when placed over Light Absorbing
Black-Out Material from Edmund Optics Inc. In another embodiment,
the luminance of the light emitted from a 1 cm.sup.2 measurement
area of the light emitting surface corresponding to light
redirected by at least one light extracting feature is less than 50
cd/m.sup.2 when exposed to a diffuse illuminance of 200 lux from an
integrating sphere when placed over Light Absorbing Black-Out
Material from Edmund Optics Inc. In another embodiment, the
luminance of the light emitted from a 1 cm.sup.2 measurement area
of the light emitting surface corresponding to light redirected by
at least one or an average of all light extracting features is less
than 25 cd/m.sup.2 when exposed to a diffuse illuminance of 200 lux
from an integrating sphere when placed over Light Absorbing
Black-Out Material from Edmund Optics Inc. in one embodiment, the
thin lightguide film permits smaller features to be used for light
extraction features or light extracting surface features to be
spaced further apart due to the thinness of the lightguide. In one
embodiment, the average largest dimensional size of the light
extracting surface features in the plane parallel to the light
emitting surface corresponding to a light emitting region of the
light emitting device is less than one selected from the group: 3
mm, 2 mm, 1 mm, 0.5 mm, 0.25 mm, 0.1 mm, 0.80 mm, 0.050 mm, 0040
mm, 0.025 mm, and 0.010 mm.
[0343] In one embodiment, the individual light extracting surface
features, regions or pixels are discernible as an individual pixel
when the device is emitting light in an on state and is not readily
discernible when the light emitting device is in the off state when
viewed at a distance greater than one selected from the group: 10
centimeters, 20 centimeters, 30 centimeters, 40 centimeters, 50
centimeters, 100 centimeters, and 200 centimeters. In this
embodiment, the area may appear to be emitting light, but the
individual pixels or sub-pixels cannot be readily discerned from
one another. In another embodiment, the intensity or color of a
light emitting region of the light emitting device is controlled by
spatial or temporal dithering or halftone printing. In one
embodiment, the average size of the light extracting regions in a
square centimeter of a light emitting region on the outer surface
of the light emitting device is less than 500 microns and the color
and/or luminance is varied by increasing or decreasing the number
of light extracting regions within a predetermined area.
[0344] In one embodiment, the light emitting device is a sign with
a light emitting surface comprising at least one selected from the
group: light emitting regions, light extracting regions, and light
extraction feature which is not readily discernible by a person
with a visual acuity between 0.5 and 1.5 arcminutes at a distance
of 20 cm when illuminated with 200 lux of diffuse light in front of
Light Absorbing Black-Out Material from Edmund Optics Inc.
[0345] In another embodiment, the fill factor of the light
extracting features, defined as the percentage of the surface area
comprising light extracting features in a light emitting region,
surface or layer of the lightguide or film, is one selected from
the group: less than 80%, less than 70%, less than 60%, less than
50%, less than 40%, less than 30%, less than 20%, and less than
10%. The fill factor can be measured within a full light emitting
square centimeter surface region or area of the lightguide or film
(bounded by regions all directions within the plane of the
lightguide which emit light) or it may be the average of the light
emitting areas of the lightguides. The fill factor may be measured
when the light emitting device is in the on state or in the of
state (not emitting light).
[0346] In another embodiment, the light emitting device is a sign
with a light emitting surface comprising light emitting regions
wherein when the device is not emitting light, the angle subtended
by two neighboring light extracting features that are visible when
the device is on, at a distance of 20 cm is less than one selected
from the group: 0.001 degrees, 0.002 degrees, 0.004 degrees, 0.008
degrees, 0.010 degrees, 0.015 degrees, 0.0167 degrees, 0.02
degrees, 0.05 degrees, 0.08 degrees, 0.1 degrees, 0.16 degrees, 0.2
degrees, 0.3 degrees, 0.4 degrees, 0.5 degrees, 0.6 degrees, 0.7
degrees, 0.8 degrees, 1 degree, 2 degrees, and 5 degrees. In
another embodiment, the light emitting device is a sign with a
light emitting surface comprising light emitting regions wherein
when the device is not emitting light, the angle subtended by two
neighboring light extracting features (that are which are not
easily visible when the device is off when illuminated with 200 lux
of diffuse light) at a distance of 20 cm is less than one selected
from the group: 0.3 degrees, 0.4 degrees, 0.5 degrees, 0.6 degrees,
0.7 degrees, 0.8 degrees, I degree, 2 degrees, and 5 degrees.
[0347] In a further embodiment, the light extraction features of
the light emitting device comprise light scattering domains of a
material with a different refractive index than the surrounding
material. In one embodiment, the light scattering domain has a
concentration within the continuous region having light scattering
domains (such as an inkjet deposited white ink pixel) less than one
selected from the group: 50%, 40%, 30%, 20%, 10%, 5%, 3%, 1%, 0.5%,
and 0.1% by volume or weight. The concentration or thickness of the
light scattering domains may vary in the x, y, or z directions and
the pixel or region may be overprinted to increase the thickness.
In another embodiment, the light extracting features have a light
absorbing region disposed between the light extracting feature and
at least one output surface of the light emitting device. For
example, the light extracting features could be titanium dioxide
based white inkjet deposited pixels deposited on a lightguide and
the light absorbing ink (such as a black dye or ink comprising
carbon black particles) is deposited on top of the white ink such
that 50% of the light scattered from the white pixel is transmitted
through the light absorbing ink. In this example, the ambient light
that would have reflected from the white ink if there were no light
absorbing ink is reduced by 75% (twice passing through the 50%
absorbing ink) and the visibility of the dots is reduced while
sufficient tight from the lightguide is emitted from the light
emitting device in the region near the white pixel. In another
embodiment, a low light transmission light absorbing material
absorbing at least one selected from the group: 5%, 10%, 20%, 30%,
40%, 50%, 60%, and 70% of the light emitted from a first light
extracting feature is disposed between the light extracting feature
and at least one outer surface of the light emitting device.
Multiple Lightguides
[0348] In one embodiment, a light emitting device comprises more
than one lightguide to provide at least one selected from the
group: color sequential display, localized dimming backlight, red,
green, and blue lightguides, animation effects, multiple messages
of different colors, NVIS and daylight mode backlight (one
lightguide for NVIS, one lightguide for daylight for example),
tiled lightguides or backlights, and large area light emitting
devices comprised of smaller light emitting devices. In another
embodiment, a light emitting device comprises a plurality of
lightguides optically coupled to each other. In another embodiment,
at least one lightguide or a component thereof comprises a region
with anti-blocking features such that the lightguides do not
substantially couple light directly into each other due to
touching. In some embodiments, the need for a cladding can be
reduced or alleviated by using anti-blocking materials to maintain
separation (and air gap) over regions of the lightguide surfaces.
In another embodiment, the light emitting device comprises a first
and second light emitting region disposed to receive light from a
first and second group of coupling lightguides, respectively,
wherein the bends or folds in the first group of coupling
lightguides are at angle selected from the group: 10 to 30 degrees,
25 degrees to 65 degrees, 70 to 110 degrees, 115 degrees to 155
degrees, 160 degrees to 180 degrees, and 5 to 180 degrees from the
bends or folds in the second group of coupling lightguides.
[0349] In another embodiment, a film-based lightguide has two
separate light emitting regions with a first and second group of
coupling lightguides disposed to couple light into the first light
emitting region and second light emitting region, respectively,
wherein the first and second groups of coupling lightguides fold or
bend to create a single light input coupler disposed to couple
light from a single source or source package into both light
emitting regions. In a further embodiment, the two separate light
emitting regions are separated by a separation distance (SD)
greater than one selected from the group: 0.1 millimeters, 0.5
millimeters, 1 millimeter, 5 millimeters, 10 millimeters, 1
centimeter, 5 centimeters, 10 centimeters, 50 centimeters, 1 meter,
5 meters, 10 meters, the width of a coupling lightguide, the width
of a fold region, a dimension of the first light emitting region
surface area, and a dimension of the second light emitting region
surface area.
[0350] In another embodiment, two film-based lightguides are
disposed above one another in at least one selected from the group:
lightguide region, light output region, light input coupler, light
input surface, and light input edge such that light from a light
source, a package of light sources, an array of light sources, or
an arrangement of light sources is directed into more than one
film-based lightguide.
[0351] In a further embodiment, a plurality of lightguides are
disposed substantially parallel to each other proximate a first
light emitting region and the lightguides emit light of a first and
second color. The colors may be the same or different and provide
additive color, additive luminance, white light emitting
lightguides, red, green, and blue light emitting lightguides or
other colors or combinations of lightguides emitting light near the
same, adjacent or other corresponding light emitting regions or
light extraction features. In another embodiment, a light emitting
device comprises a first lightguide and a second lightguide wherein
a region of the second lightguide is disposed beneath first
lightguide in a direction parallel to the optical axis of the light
emitting device or parallel to the normal to the light emitting
surface of the device and at least one coupling lightguide from the
first light lightguide is interleaved between at least two coupling
lightguides from the second lightguide. In a further embodiment,
the coupling lightguides from the first lightguide film are
interleaved with the coupling lightguides of the second lightguide
region. For example, two film-based lightguides with coupling
lightguide strips oriented parallel to each other along one edge
may be folded together to form a single light input surface wherein
the light input edges forming the light input surface alternate
between the lightguides. Similarly, three or more lightguides with
light input edges 1, 2, and 3 may be collected through folding into
a light input surface with alternating input edges in a
1-2-3-1-2-3-123 . . . pattern along a light input surface.
[0352] In another embodiment, a light emitting device comprises a
first lightguide and a second lightguide wherein a region of the
second lightguide is disposed beneath first lightguide in a
direction parallel to the optical axis of the light emitting device
or parallel to the normal to the light emitting surface of the
device and a first set of the coupling lightguides disposed to
couple light into the first lightguide form a first light input
surface and are disposed adjacent a second set of coupling
lightguides disposed to couple light into the second lightguide.
The first and second set of lightguides may be in the same light
input coupler or different light input coupler disposed adjacent
each other and they may be disposed to receive light from the same
light source, a collection of light sources, different light
sources, or different collections of light sources.
Multiple Lightguides to Reduce Bend Loss
[0353] In another embodiment, a light emitting device comprises a
first lightguide and a second lightguide wherein a first
overlapping region of the second lightguide is disposed beneath
first lightguide in a direction parallel to the optical axis of the
light emitting device or parallel to the normal to the light
emitting surface of the device and the first and second set of
coupling lightguides disposed to couple light into the first and
second lightguides, respectively, have a total bend loss less than
that of a set of coupling lightguides optically coupled to a
lightguide covering the same input dimension of each first and
second coupling lightguide with the same radius of curvature as the
average of the first and second set of coupling lightguides and a
core thickness equal to the total core thicknesses of the first and
second lightguides in the first overlapping region.
[0354] In a further embodiment, multiple lightguides are stacked
such that light output from one lightguide passes through at least
one region of another lightguide and the radii of curvature for a
fixed bend loss (per coupling lightguide or total loss) is less
than that of a single lightguide with the same light emitting area,
same radius of curvature; and the thickness of the combined
lightguides. For example, for a bend loss of 70%, a first
lightguide of a first thickness may be limited to a first radius of
curvature. By using a second and third lightguide with each at half
the thickness of the first lightguide, the radius of curvature of
each of the second and third lightguides can be less to maintain
only 70% bend loss due to the reduced thickness of each lightguide.
In one embodiment, multiple thin lightguides, each with a radius of
curvature less than a thicker lightguide with the same bend loss,
reduce the volume and form factor of the light emitting device. The
light input surfaces of the coupling lightguides from the different
lightguides may be disposed adjacent each other in a first
direction, on different sides of the light emitting device, within
the same light input coupler, within different light input
couplers, underneath each other, alongside each other, or disposed
to receive light from the same or different light sources.
Multiple Lightguides Connected by Coupling Lightguides
[0355] In one embodiment, two or more lightguides are optically
coupled together by a plurality of coupling lightguides. In one
embodiment a film comprises a first continuous lightguide region
and strip-like sections cut in a region disposed between the first
continuous lightguide region and a second continuous lightguide
region. In one embodiment, the strips are cut and the first and
second continuous lightguide regions are translated relative to
each other such that the strips (coupling lightguides in this
embodiment) are folding and overlapping. The resulting first and
second lightguide regions may be separate regions such as a keypad
illuminator and an LCD backlight for a cellphone which are
connected by the coupling lightguides. The first and second
lightguide regions may also both intersect a light normal to the
film surface in one or more regions such that the first and second
lightguide regions at least partially overlap. The first and second
lightguide regions may have at least one light input coupler. By
coupling the first and second lightguide regions together through
the use of coupling lightguides, the light from an input coupler
coupled into the first lightguide region is not lost, coupled out
of, or absorbed when it reaches the end of the first lightguide
region and may further propagate to the second lightguide region.
This can allow more light extraction regions for a specific region
since the lightguides overlap in a region. In one embodiment, at
least one region disposed to receive light between the first and
second lightguide regions may comprise a light absorbing filter
such that the light reaching the second lightguide region comprises
a different wavelength spectral profile and a second color can be
extracted from the second lightguide region different to the first
color extracted from the first lightguide extracting region. More
than two lightguide regions illuminated by a first input coupler
with one, two, or more than two light emitting colors may be used
and separate lightguides (or lightguide regions) with separate
light input couplers may be disposed behind, between, or above one
or more of the lightguide regions illuminated by the first input
coupler. For example, a first light input coupler directs white
light from an LED into the first lightguide region wherein the
light extracting regions extract light creating a first white
image, and the light which is not extracted passes into coupling
lightguides on the opposite end which have a striped region
optically coupled to the lightguide (such as an red colored ink
stripe) which substantially absorbs the non-red portions of the
spectrum. This light further propagates into the second lightguide
region where a portion of the light is extracted out of the
lightguide as red light in a red image. Similarly, other colors
including subtractive colors may be used to create multiple-colors
of light emitting from multiple lightguide regions and the light
extracting region may overlap to create additive color mixing. Two
or more lightguides or lightguide regions may overlap wherein the
optical axes of the light propagating within the lightguide are at
approximately 90 degrees to each other.
Lightguide Folding Around Components
[0356] In one embodiment, at least one selected from the group:
lightguide, lightguide region, light mixing region, plurality of
lightguides, coupling lightguides, and light input coupler bends or
folds such that other components of the light emitting device are
hidden from view, located behind another component or the light
emitting region, or are partially or fully enclosed. These
components around which they may bend or fold include components of
the light emitting device such as light source, electronics,
driver, circuit board, thermal transfer element, spatial light
modulator, display, housing, holder, or other components are
disposed behind the folded or bent lightguide or other region or
component. In one embodiment, a frontlight for a reflective display
comprises a lightguide, coupling lightguides and a light source
wherein one or more regions of the lightguide are folded and the
light source is disposed substantially behind the display.
Curled Edge of Lightguide to Recycle Light
[0357] In one embodiment, a lightguide edge region is curled back
upon itself and optically coupled to a region of the lightguide
such that light propagating toward the edge will follow the curl
and propagate back into the lightguide. In one embodiment, the
cladding area is removed from the lightguide from both surfaces
which are to be optically coupled or bonded together. More than one
edge may be curled or bent back upon itself to recycle light back
into the lightguide.
Registration Holes and Cavities
[0358] One embodiment, at least one selected from the group:
lightguide, lightguide region, light mixing region, light input
coupler, housing, holding device and plurality of coupling
lightguides comprises at least one opening or aperture suitable for
registration with another component of the device that contains at
least one pin or object which may pass through the at least one
opening or aperture. In another embodiment, one or more of the
light turning optical element, coupling lightguides, light
redirecting optical element, light coupling optical element,
relative position maintaining optical element, circuit board,
flexible connector, film based touchscreen, film-based lightguide,
and display film substrate comprises a registration opening,
aperture, hole, or cavity.
Alignment Guide
[0359] In another embodiment, the light turning optical element has
an alignment guide physically coupled to the light turning optical
element such that the guide directs the coupling lightguide input
surfaces to align in at least one of the following directions: a
direction perpendicular to the film surface of the coupling
lightguides, a direction parallel to the coupling lightguide film
surfaces, a direction parallel to the optical axis of the light
source, and a direction orthogonal to the optical axis of the light
source. In one embodiment, the alignment guide is physically
coupled to one or more the following: the light turning optical
element, coupling lightguides, light redirecting optical element,
light coupling optical element, relative position maintaining
optical element, circuit board, light source, light source housing,
optical element holder or housing, input coupler housing, alignment
mechanism, heat sink for the light source, flexible connector,
film-based touchscreen, film-based lightguide, and display film
substrate. In one embodiment, the alignment guide comprises an
alignment arm such as a metal or plastic bar or rod with a flexural
modulus of one of the following: 2 times, 3 times, 4 times, and 5
times that of the stacked array of coupling lightguides that it is
disposed to guide a stack of coupling lightguides (or an optical
element) in a predetermined direction. The alignment guide may have
one or more curved regions to assist in the guiding function
without scratching or damaging the coupling lightguide through
sharp edges. In another embodiment, the alignment guide is a
cantilever spring that can apply a force against one or more
coupling lightguides to maintain the position of the coupling
lightguide temporarily or permanently. In another embodiment, the
alignment guide maintains the relative position of the coupling
lightguide near the light input surface while an additional,
permanent relative position method is employed (such as
mechanically clamping, adhering using adhesives, epoxy or optical
adhesive, forming a housing around the coupling lightguides, or
inserting the coupling into a housing) which substantially
maintains the relative position of the coupling lightguides to the
light source or light input coupler. In another embodiment, a
cladding layer (such as a low refractive index adhesive) is
disposed on one or more of the following: the top surface, bottom
surface, lateral edges, and light input surface of an array of
coupling lightguides such that when the alignment guide is
thermally coupled to the array of coupling lightguides, less light
is absorbed by the alignment guide.
Alignment Cavity within the Alignment Guide
[0360] In one embodiment, the alignment guide comprises a cavity
within a mechanical coupler in which a stacked array of coupling
lightguides may be disposed to align their light input edges to
receive light from a light source. In one embodiment, the alignment
guide comprises a thermal transfer element with an extended arm or
rod to align the coupling lightguides in one dimension, apply force
vertical force to the coupling lightguides to assist holding them
at the correct lateral position and a cavity into which the input
surface of the coupling lightguides may be placed such that they
are aligned to receive light from the light source. In another
embodiment, the alignment guide comprises a thermal transfer
element with an extended arm (functioning as a cantilever spring to
apply force) and a cavity with a cross sectional vertical and width
dimension at least as large as the vertical and width dimensions,
respectively, of the cross-section of the stacked array of coupling
lightguides near their light input surfaces.
Thermally Conductive Alignment Guide
[0361] In another embodiment, the alignment guide is thermally and
physically coupled to the heat sink for the light source. For
example, the alignment guide may comprise an aluminum heat sink
disposed around and thermally coupled to the light source with an
alignment cavity opening disposed to receive the coupling
lightguide such that they are held within the cavity. In this
embodiment, the aluminum heat sink serves an alignment function and
also reduces the heat load from the light source. In another
embodiment, the alignment guide comprises an alignment cavity in a
thermally conducting material (such as a metal, aluminum, copper,
thermally conductive polymer, or a compound comprising thermally
conductive materials) thermally coupled to the coupling lightguides
such that the alignment guide removes heat from the coupling
lightguides received from the light source. When using high power
LEDs, for example, the heat from the light source could potentially
damage or cause problems with the coupling lightguides (softening,
thermal or optical degradation, etc.). By removing the heat from
the coupling lightguides, this effect is reduced or eliminated. In
one embodiment, the alignment guide is thermally coupled to one or
more coupling lightguides by physical contact or through the use of
an intermediate thermally conductive material such as a thermally
conductive adhesive or grease.
Other Components
[0362] In one embodiment, the light emitting device comprises at
least one selected from the group: power supply, batteries (which
may be aligned for a low profile or low volume device), thermal
transfer element (such as a heat sink, heat pipe, or stamped sheet
metal heat sink), frame, housing, heat sink extruded and aligned
such that it extends parallel to at least one side of the
lightguide, multiple folding or holding modules along a thermal
transfer element or heat sink, thermal transfer element exposed to
thermally couple heat to a surface external to the light emitting
device, and solar cell capable of providing power, communication
electronics (such as needed to control tight sources, color output,
input information, remote communication, Wi-Fi control, Bluetooth
control, wireless internet control, etc.), a magnet for temporarily
affixing the light emitting device to a ferrous or suitable
metallic surface, motion sensor, proximity sensor, forward and
backwards oriented motion sensors, optical feedback sensor
(including photodiodes or LEDs employed in reverse as detectors),
controlling mechanisms such as switches, dials, keypads (for
functions such as on/off, brightness, color, color temp, presets
(for color, brightness, color temp, etc.), wireless control),
externally triggered switches (door closing switch for example),
synchronized switches, and light blocking elements to block
external light from reaching the lightguide or lightguide region or
to block light emitted from a region of the light emitting device
from being seen by a viewer.
[0363] In one embodiment, a light emitting device comprises a first
set of light sources comprising a first and second light source
disposed to couple light into a first and second light input
coupler, respectively, and further comprising a second set of light
sources comprising a third and fourth light source disposed to
couple light into a first and second light input coupler,
respectively, wherein the first set of light sources are thermally
coupled to each other and the second set of light sources are
thermally coupled to each other by means of one selected from the
group metal core printed circuit board, aluminum component, copper
component, metal alloy component, thermal transfer element, or
other thermally conducting element. In a further embodiment, the
first and second set of light sources are substantially thermally
isolated by separating the light sources (or substrates for the
light sources such as a PCB) in the region proximate the light
sources by an air gap or substantially thermally insulating
material such as polymer substantially free of metallic, ceramic,
or thermally conducting components. In another embodiment, the
first and third light sources are disposed closer to each other
than the first and second light sources and more heat from the
first light source reaches the second light source than reaches the
third light source when only the first light source is emitting
light. More than two light sources disposed to couple light into
more than two coupling lightguides may be thermally coupled
together by a thermal transfer element and may be separated from a
second set of more than two light sources by an air gap or
thermally insulating material.
[0364] In another embodiment, a light emitting device comprises a
film lightguide that emits light and also detects light changes
within the lightguide and provides touch screen functionality. In
one embodiment, a film lightguide comprises coupling lightguides
disposed to receive light from a light source and direct the light
into a lightguide to provide a backlight or frontlight and at least
one coupling lightguide disposed to detect changes in light
intensity (such as lower light levels due to light being frustrated
and absorbed by coupling light into a finger in touched location).
More than one light intensity detecting lightguide may be used.
Other configurations for optical lightguide based touch screens are
known in the art and may be used in conjunction with
embodiments.
[0365] In another embodiment a touchscreen comprises at least two
film lightguides. In another embodiment, a touchscreen device
comprises a light input coupler used in reverse to couple light
from a film lightguide into a detector. In another embodiment, the
light emitting device or touch screen is sensitive to pressure in
that when a first film or first lightguide is pressed or pressure
is applied, the first film is moved into sufficient optical contact
with a second film or second lightguide wherein at least one of
light from the first lightguide or first lightguide is coupled into
is coupled into the second film or second lightguide, light from
the second film or second lightguide is coupled into the first film
or first lightguide, or light couples from each lightguide or film
into the other.
Thermal Transfer Element Coupled to Coupling Lightguide
[0366] In another embodiment, a thermal transfer element is
thermally coupled to a cladding region, lightguide region,
lightguide, coupling lightguide, stack or arrangement of coupling
lightguides, combination of folded regions in a coupling
lightguide, input coupler, window or housing component of the light
input coupler, or housing. In another embodiment, the thermal
transfer element is thermally coupled to the coupling lightguides
or folded regions of a coupling lightguide to draw heat away from
the polymer based lightguide film in that region such that a high
power LED or other light source emitting heat toward the
lightguides may be used with reduced thermal damage to the polymer.
In another embodiment, a thermal transfer element is physically and
thermally coupled to the cladding region of the light input
couplers or folded regions of a coupling lightguide. The thermal
transfer element may also serve to absorb light in one more
cladding regions by using a thermal transfer element that is black
or absorbs a significant amount of light (such as having a diffuse
reflectance spectral component included less than 50%). In another
embodiment, the top surface of the upper coupling lightguide and
the bottom surface of the bottom coupling lightguide comprise
cladding regions in the regions of the coupling lightguides or
folded regions of the coupling lightguide near the light input
edges. By removing (or not applying or disposing) the cladding
between the coupling lightguides or folded regions, more light can
be coupled into the coupling lightguides or folded regions from the
light source. Outer cladding layers or regions may be disposed on
the outer surfaces to prevent light absorption from contact with
other elements or the housing, or it may be employed on the top or
bottom surface, for example, to physically and thermally couple the
cladding region to a thermal transfer element to couple the heat
out without absorbing light from the core region (and possibly
absorbing light within the core region).
[0367] In one embodiment, a light emitting device comprises a
thermal transfer element disposed to receive heat from at least one
light source wherein the thermal transfer element has at least one
selected from the group: total thickness, average total thickness,
and average thickness, all in the direction perpendicular to the
light emitting device light emitting surface less than one selected
from the group: 10 millimeters, 5 millimeters, 4 millimeters, 3
millimeters, 2 millimeters, 1 millimeter, and 0.5 millimeters. In
one embodiment, the thermal transfer element comprises a sheet or
plate of metal disposed on the opposite side of the lightguide as
the light emitting surface of the light emitting device. In a
further embodiment, a low thermal conductivity component is
disposed between the thermal transfer element and the lightguide.
In another embodiment, the low thermal conductivity component has a
thermal conductivity, k, less than one selected from the group:
0.6, 0.5, 0.4, 0.3, 0.2, 0.1 and 0.05 Wm-1K-1 at a temperature of
296 degrees Kelvin. In a further embodiment, the low thermal
conductivity component is a white reflective polyester based film
(or PIPE based film), in a further embodiment, a light emitting
device comprises a low thermal conductivity component physically
coupled to the thermal transfer element and the light emitting
device further comprises at least one selected from the group: low
refractive index material, cladding region, and a region with an
air gap disposed between the low thermal conductivity component and
the lightguide.
[0368] In a further embodiment, the thermal transfer element is an
elongated component with a dimension in first direction at least
twice as long as the dimension in either mutually orthogonal
direction orthogonal to the first direction wherein a portion of
the thermal transfer element is disposed within the bend region of
at least one light input coupler. In another embodiment, a light
emitting device comprises a light input coupler wherein a portion
of the smallest rectangular cuboid comprising all of the coupling
lightguides within the light input coupler comprises a thermal
transfer element. In another embodiment, a light emitting device
comprises a light input coupler wherein a portion of the smallest
rectangular cuboid comprising all of the coupling lightguides
within the light input coupler comprises an elongated thermal
transfer element selected from the group: pipe from a heat pipe,
elongated heat sink, metal thermal transfer element with fins, rod
inside the thermal transfer element, and metal frame.
[0369] In another embodiment, the thermal transfer element
comprises at least one metal frame component or elongated metal
component that provides at least one selected from the group:
increased rigidity, frame support for suspension or mounting,
protection from accidental contact, and frame support for a fiat or
predefined non-planar surface. In a further embodiment, the thermal
transfer element comprises at least two regions or surfaces
oriented at an angle with respect to each other or an opening
through the volume that form at least a portion of a channel
through which air may flow through. In one embodiment, the light
emitting device comprises a plurality of air channels formed by at
least one surface of the thermal element through which air flows
and convects heat away by active or passive air convection from the
source generating the heat (such as a light source or a processor).
In one embodiment, the light emitting device comprises a plurality
of air channels along vertically oriented sides of the device
through which air flows and convects heat through (naturally or
forced air). In another embodiment, the thermal transfer element
has a thermal conductivity greater than one selected from group of
0.5, 0, 7, 1, 2, 5, 10, 50, 100, 200, 300, 400, 800, and 1000
Wm-1K-1 at a temperature of 296 degrees Kelvin.
Other Optical Films
[0370] In another embodiment, the light emitting device further
comprises a light redirecting optical film, element, or region that
redirects light incident at a first range of angles, wavelength
range, and polarization range into a second range of angles
different than the first.
Light Redirecting Optical Element
[0371] In one embodiment, the light redirecting optical element is
disposed between at least one region of the light emitting region
and the outer surface of the light emitting device (which may be a
surface of the light redirecting optical element). In a further
embodiment, the light redirecting optical element is shaped or
configured to substantially conform to the shape of the light
emitting region of the light emitting device. For example, a light
emitting sign may comprise a lightguide film that is substantially
transparent surrounding the light emitting region that is in the
shape of indicia; wherein the lightguide film comprises light
extraction features in the region of the indicia; and a light
redirecting optical element (such as a film with substantially
hemispherical light collimating surface features) cut in the shape
of the light emitting region is disposed between the light emitting
region of the lightguide film and the light emitting surface of the
light emitting device. In another embodiment, a light emitting sign
comprises a film-based lightguide and a light redirecting optical
element comprising a lens array formed from lenticules or
microlenses (such as substantially hemispherical lenses used in
integral images or 3D integral displays or photographs) disposed to
receive light from the lightguide wherein the lens array separates
light from the lightguide into two or more angularly separated
images such that the sign displays stereoscopic images or indicia.
The shape of the lens array film or component in the plane parallel
to the lightguide film may be substantially conformal to the shape
of the light emitting region or one or more sub-regions of the
light emitting regions such that sign emits angularly separated
information in the entire light emitting region or one or more
sub-regions of the light emitting region. For example, the sign may
have a first two dimensional text region and a second region with a
stereoscopic image.
Light Reflecting Film
[0372] In another embodiment, a light emitting device comprises a
lightguide disposed between a light reflecting film and the light
emitting surface of the light emitting device. In one embodiment,
the light reflecting film is a light reflecting optical element.
For example, a white reflective polyester film of at least the same
size and shape of the light emitting region may be disposed on the
opposite side of the lightguide as the light emitting surface of
the light emitting device or the light reflecting region may
conform to the size and shape of one or all of the light emitting
regions, or the light reflecting region may be of a size or shape
occupying a smaller area than the light emitting region. A light
reflecting film or component substantially the same shape as the
light emitting region or region comprising light extracting
features may maintain the transparency of the light emitting device
in the regions surrounding or between the light emitting regions or
regions comprising light extracting features while increasing the
average luminance in the region on the light emitting surface of
the light emitting device by at least one selected from the group:
20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 100%, and 110% by
reflecting a portion of the light received toward the light
emitting surface.
[0373] In one embodiment, the light redirecting optical film,
element or region comprises at least one surface or volumetric
feature selected from the group: refractive, prismatic, totally
internally reflective, specular reflective element or coating,
diffusely reflective element or coating, reflective diffractive
optical element, transmissive diffractive optical element,
reflective holographic optical element, transmissive holographic
optical element, reflective light scattering, transmissive light
scattering, light diffusing, multi-layer anti-reflection coating,
moth-eye or substantially conical surface structure type
anti-reflection coating, Giant Birefringent Optic multilayer
reflection, specularly reflective polarizer, diffusely reflective
polarizer, cholesteric polarizer, guided mode resonance reflective
polarizer, absorptive polarizer, transmissive anisotropic
scattering (surface or volume), reflective anisotropic scattering
(surface or volume), substantially symmetric or isotropic
scattering, birefringent, optical retardation, wavelength
converting, collimating, light redirecting, spatial filtering,
angular dependent scattering, electro-optical (PDLC, liquid
crystal, etc.), electrowetting, electrophoretic, wavelength range
absorptive filter, wavelength range reflective filter, structured
nano-feature surface, light management components, prismatic
structured surface components, and hybrids of two or more of the
aforementioned films or components.
[0374] Some examples of light redirecting optical films with
prismatic structured surfaces may include, but are not limited to,
Vikuiti.TM. Brightness Enhancement Film (BEF I, BEF Ii, BEF BEF III
90/50 5T, BEF III 90/50 M, BEF III 90/50 M2, BEF II 90/50 7T, BEF
III 90/50 10T, BEF III 90/50 AS), Vikuiti.TM. Transparent Right
Angle Film (TRAF), Vikuiti.TM. Optical Lighting Film (OLF or SOLE),
IDE II, TRAF II, or 3M.TM. Diamond Graderm Sheeting, all of which
are available from 3M Company, St, Paul, Minn. Other examples of
light management component constructions may include the rounded
peak/valley films described in U.S. Pat. Nos. 5,394,255 and
5,552,907 (both to Yokota et al.), Reverse Prism Film from
Mitsubishi Rayon Co., Ltd or other totally internally reflection
based prismatic film such as disclosed in U.S. Pat. Nos. 6,746,130,
6,151,169, 5,126,882, and 6,545,827, lenticular lens array film,
microlens array film, diffuser film, microstructure BEF,
nanostructure BEF, Rowlux microlens film from Rowland Technologies,
films with arrangements of light concentrators such as disclosed in
U.S. Pat. No. 7,160,017, and hybrids of one or more of the
aforementioned films.
[0375] In another embodiment, the light emitting device further
comprises an angularly selected light absorbing film, element or
region. Angularly selective light absorbing films may substantially
transmit light within a first incident angular range and
substantially absorb light within a second incident angular range.
These films can reduce glare light, absorb undesired light at
specific angles (such as desired in military applications where
stray or unwanted light can illuminate parts of the cockpit or the
windshield causing stray reflections. Louver films, such as those
manufactured by skiving a multi-layered material at a first angle
are known in the display industry and include louver films such as
3M.TM. Privacy Film by 3M Company and other angular absorbing or
redirecting films such as those disclosed in U.S. Pat. Nos.
7,467,873; 3,524,789; 4,788,094; and 5,254,388.
Angular Broadening Element
[0376] In a further embodiment, a light emitting device comprises a
light redirecting element disposed to collimate or reduce the
angular FWHM of the light from the lightguide, a spatial light
modulator, and an angular broadening element such as a diffuser or
light redirecting element disposed on the viewing side of the
spatial light modulator to increase the angular FWHM of the light
exiting the spatial light modulator. For example, light may be
collimated to pass through or onto pixels or sub-pixels of a
spatial light modulator and the light may then angularly broadened
(increase the angular FWHM) to increase the angle of view of the
device. In a further embodiment, the angular broadening element is
disposed within or on a component of the spatial light modulator.
For example, a diffuser may be disposed between the outer glass and
the polarizer in a liquid crystal display to broaden the collimated
or partially collimated light after it has been spatially modulated
by the liquid crystal layer. In a further embodiment, the light
emitting device may further comprise a light absorbing film,
circular polarizer, microlens type projection screen, or other rear
projection type screen to absorb a first portion of the ambient
light incident on the light emitting surface to improve the
contrast.
Light Absorbing Region or Layer
[0377] In one embodiment, at least one selected from the group:
cladding, adhesive, layer disposed between the lightguide or
lightguide region and the outer light emitting surface of the light
emitting device, patterned region, printed region, and extruded
region on one or more surfaces or within the volume of the film
comprises a light absorbing material which absorbs a first portion
of light in a first predetermined wavelength range. In one
embodiment, the first predetermined wavelength range includes light
from 300 nm to 400 nm and the region absorbs UV light that could
degrade or yellow the lightguide region, layer or other region or
layer. In one embodiment, the cladding region is disposed between
the light absorbing region and the lightguide such that the light
propagating through the lightguide and the evanescent portion of
the light propagating within the lightguide is not absorbed due to
the absorbing region since it does not pass through the absorbing
region unless it is extracted from the lightguide. In another
embodiment, the light absorbing region or layer is an arrangement
of light absorbing, light fluorescing, or light reflecting and
absorbing regions which selectively absorb light in a predetermine
pattern to provide a light emitting device with spatially varying
luminance or color (such as in a dye-sublimated or inject printed
overlay which is laminated or printed onto a layer of the film to
provide a colored image, graphic, logo or indicia). In another
embodiment, the light absorbing region is disposed in close
proximity to the light extracting region such that the light
emitted from the light emitting device due to the particular light
extraction feature has a predetermined color or luminous intensity.
For example, inks comprising titanium dioxide and light absorbing
dyes can be disposed on the lightguide regions such that a portion
of the light reaching the surface of the lightguide in that region
passes through the dye and is extracted due to the light extraction
feature or the light is extracted by the light extraction feature
and passes through the dye.
[0378] In one embodiment, a tight emitting device comprises a five
layer lightguide region with a UV light absorbing material disposed
in the outer layers which are both optically coupled to cladding
layers which are both optically coupled to the inner lightguide
layer. In one embodiment, a 5 layer film comprises a polycarbonate
material in the central lightguide layer with low refractive index
cladding layers of a thickness between 1 micron and 150 microns
optically coupled to the lightguide layer and a UV light absorbing
material in the outer layers of the film.
[0379] In another embodiment, alight absorbing material is disposed
on one side of the tight emitting device such that the light
emitted from the device is contrasted spatially against a darker
background. In one embodiment, a black PET layer or region is
disposed in proximity to one side or region of the light emitting
device. In another embodiment, white reflecting regions are
disposed in proximity to the light extracting region such that the
light escaping the lightguide in the direction of the white
reflecting region is reflected back toward the lightguide. In one
embodiment, a lightguide comprises a lightguide region and a
cladding region and a light absorbing layer is disposed (laminated,
coated, co-extruded, etc.) on the cladding region. In one
embodiment, light from a laser cuts (or ablates) regions in the
light absorbing layer and creates light extracting regions in the
cladding region and/or lightguide region. A white reflecting film
such as a white PET film with voids is disposed next to the light
absorbing region. The white film may be laminated or spaced by an
air gap, adhesive or other material. In this example, a portion of
the light extracted in the light extracting regions formed by the
laser is directed toward the white film and reflected back through
the lightguide where a portion of this tight escapes the lightguide
on the opposite side and increases the luminance of the region.
This example illustrates where registration of the white reflecting
region, black reflection region, and light extracting regions are
not necessary since the laser created holes in the black film and
created the light extracting features at the same time. This
example also illustrates the ability for the light emitting device
to display an image, logo, or indicia in the off state where light
is not emitted from the light source since the white reflective
regions reflect ambient light. This is useful, for example, in a
sign application where power can be saved during the daytime since
ambient light can be used to illuminate the sign. The light
absorbing region or layer may also be a colored other than black
such as red, green, blue, yellow, cyan, magenta, etc.
[0380] In another embodiment, the light absorbing region or layer
is a portion of another element of the light emitting device. In
one embodiment, the light absorbing region is a portion of the
black housing comprising at least a portion of the input coupler
that is optically coupled to the cladding region using an
adhesive.
[0381] In another embodiment, the cladding, outer surface or
portion of the lightguide of a light emitting device comprises a
light absorbing region such as a black stripe region that absorbs
more than one selected from the group: 50%, 60%, 70%, 80% and 90%
of the visible light propagating within the cladding region. In
another embodiment, the lightguide is less than 200 microns in
thickness and a light absorbing region optically coupled to the
cladding absorbs more than 70% of the light propagating within the
cladding which passes through the lightguide wherein the width of
the light absorbing region in the direction of the light
propagating within the lightguide is less than one selected from
the group: 10 millimeters, 5 millimeters, 3 millimeters, 2
millimeters, and 1 millimeter. In another embodiment, the light
absorbing region has a width in the direction of propagation of
light within the lightguide between one selected from the group:
0.5-3 millimeters, 0.5-6 millimeters, 0.5-12 millimeters, and
0.05-10 centimeters.
[0382] In one embodiment, the light absorbing region is at least
one selected from the group: a black material patterned into a
line, a material patterned into a shape or collection of shapes, a
material patterned on one or both sides of the film, cladding, or
layer optically coupled to the cladding, a material patterned on
one or more lightguide couplers, a material patterned in the light
mixing region, a material patterned in the lightguide, and a
material patterned in the lightguide region. In another embodiment,
the light absorbing region is patterned during the cutting step for
the film, coupling lightguides, or cutting step of other regions,
layers or elements. In another embodiment, the light absorbing
region covers at least one percentage of surface area of the
coupling lightguides selected from the group: 1%, 2%, 5%, 10%, 20%,
and 40%.
Adhesion Properties of the Lightguide, Film, Cladding or Other
Layer
[0383] In one embodiment, at least one selected from the group:
lightguide, light transmitting film, cladding, and layer disposed
in contact with a layer of the film has adhesive properties. In one
embodiment, the cladding is a "low tack" adhesive that allows the
film to be removed from a window or substantially planar surface
while "wetting out" the interface. By "wetting out" the interface
as used herein, the two surfaces are optically coupled such that
the Fresnel reflection from the interfaces at the surface is less
than 2%. The adhesive layer or region may comprise a polyacrylate
adhesive, animal glue or adhesive, carbohydrate polymer as an
adhesive, natural rubber based adhesive, polysulfide adhesive,
tannin based adhesive, lignin based adhesive, furan based adhesive,
urea formaldehyde adhesive, melamine formaldehyde adhesive,
isocyanate wood binder, polyurethane adhesive, polyvinyl and
ethylene vinyl acetate, hot melt adhesive, reactive acrylic
adhesive, anaerobic adhesive, or epoxy resin adhesive.
[0384] In one embodiment, the adhesive layer or region has an ASTM
D 903 (modified for 72 hour dwell time) peel strength to standard
window glass less than one selected from the group 77 N/100 mm, 55
N/100 mm, 44 N/100 mm, 33 N/100 mm, 22 N/100 mm, and 11 N/100 mm.
In another embodiment, the adhesive, when adhered to glass, will
support the weight of the light emitting device.
Removable Protective Layer
[0385] In one embodiment, the light emitting device comprises a
removable protective layer. In another embodiment, a light
transmitting film is disposed on the outer surface of the light
emitting device and the ASTM D 903 (modified for 72 hour dwell
time) peel strength to the lightguide is less than one selected
from the group 77 N/100 min, 55 N/100 mm, 44 N/1.00 mm, 33 N/100
min, 22 N/100 mm, and 11 N/100 mm. In another embodiment, when the
outer surface of the light emitting device becomes scratched,
damaged, or reduces the optical performance of the light emitting
device, the outer layer of the film may be removed. In a further
embodiment, a tag or extended region of the protective layer allows
the individual layer to be removed while maintaining the integrity
or position of the lightguide beneath which may have one or more
additional protective layers disposed thereupon. In one embodiment,
a thin film-based lightguide disposed as a frontlight for a
reflective display comprises removable protective layers. The
protective layers may be thin or thick and may comprise materials
such as those used as display screen protectors, anti-reflection
coatings, anti-glare coatings or surfaces, hardcoatings, circular
polarizers, or surface structures that reduce the visibility of
fingerprints such as those disclosed in U.S. patent application
Ser. No. 12/537,930.
Lightguide Comprising Circuitry or Electrical Components
[0386] In one embodiment, at least one electrical component is
physically disposed on the lightguide or a layer physically coupled
to the lightguide. By incorporating electrical components on the
lightguide film, a separate substrate for one or more electrical
components is not needed (thus lower volumes and component costs)
and flexible roll-to-roll processing can be employed to manufacture
or dispose the electrical component on the lightguide film. In
another embodiment, the lightguide comprises at least one
electrical component physically coupled to a cladding region, a
cladding layer, or a layer or region physically coupled to the core
material or the cladding material. In another embodiment, a light
emitting device comprises a flexible layer comprising a plurality
of electrical components and the layer is physically coupled to a
flexible lightguide film. In one embodiment, a lightguide comprises
at least one electrical component or component used with electrical
component disposed thereon, wherein the at least one component is
selected from the group: active electrical component, passive
electrical component, transistor, thin film transistor, diode,
resistor, terminal, connector, socket, cord, lead, switch, keypad,
relay, reed switch, thermostat, circuit breaker, limit switch,
mercury switch, centrifugal switch, resistor, trimmer,
potentiometer, heater, resistance wire, thermistor, varistor, fuse,
resettable fuse, metal oxide varistor, inrush current limiter, gas
discharge tube, circuit breaker, spark gap, filament lamp,
capacitor, variable capacitor, inductor, variable inductor,
saturable inductor, transformer, magnetic amplifier, ferrite
impedance, motor, generator, solenoid, speaker, microphone, RC
circuit, LC circuit, crystal, ceramic resonator, ceramic filter,
surface acoustic wave filter, transducer, ultrasonic motor, power
source, battery, fuel cell, power supply, photovoltaic device,
thereto electric generator, electrical generator, sensor, buzzer,
linear variable differential transformer, rotary encoder,
inclinometer, motion sensor, flow meter, strain gauge,
accelerometer, thermocouple, thermopile, thermistor, resistance
temperature detector, bolometer, thermal cutoff, magnetometer,
hygrometer, photo resistor, solid state component, standard diode,
rectifier, bridge rectifier, Schottky diode, hot carrier diode,
zener diode, transient voltage suppression diode, varactor, tuning
diode, varicap, variable capacitance diode, light emitting diode,
laser, photodiode, solar cell, photovoltaic cell, photovoltaic
array, avalanche photodiode, diode for alternating current, DIAC,
trigger diode, SIDAC, current source diode, Peltier cooler,
transistor, bipolar transistor, bipolar junction transistor,
phototransistor, Darlington transistor (NPN or PNP), Sziklai pair,
field effect transistor, junction field effect transistor, metal
oxide semiconductor FET, metal semiconductor FET, high electron
mobility transistor, thyristor, unijunction transistor,
programmable unijunction transistor, silicon controlled rectifier,
static induction transistor/thyristor, triode for alternating
current, composite transistor, insulated gate bipolar transistor,
hybrid circuits, optoelectronic circuit, opto-isolator,
opto-coupler, photo-coupler, photodiode, BJT, JFET, SCR, TRIAC,
open collector IC, CMOS IC, solid state relay, opto switch, opto
interrupter, optical switch, optical interrupter, photo switch,
photo interrupter, led display, vacuum fluorescent display, cathode
ray tube, liquid crystal display (preformed characters, dot matrix,
passive matrix, active matrix TFT, flexible display, organic LCD,
monochrome LCD, color LCD), diode, triode, tetrode, pentode,
hexode, pentagrid, octode, barretter, nuvistor, compactron,
microwave, klystron, magnetron, multiple electronic components
assembled in a device that is in itself used as a component,
oscillator, display device, filter, antennas, elemental dipole,
biconicat, yagi, phased array, magnetic dipole (loop), wire-wrap,
breadboard, enclosure, heat sink, heat sink paste & pads, fan,
printed circuit hoards, lamp, memristor, integrated circuit,
processor, memory, driver, and electrical leads and
interconnects.
[0387] In another embodiment, the electrical component comprises
organic components. In one embodiment, at least one electrical
component is formed on the lightguide, on a component of the
lightguide, or on a layer physically coupled to the lightguide
material using roll-to-roll processing. In a further embodiment, a
flexible lightguide film material is physically coupled to at least
one flexible electrical component or a collection of electrical
components such that the resulting lightguide is flexible and has
can emit light without temporary or permanent visible demarcation,
crease, luminance non-uniformity, MURA, or blemish when a light
emitting region is bent to a radius of curvature less than one
selected from the group: 100 millimeters, 75 millimeters, 50
millimeters, 25 millimeters, 10 millimeters and 5 millimeters.
Light Redirecting Element Disposed to Redirect Light from the
Lightguide
[0388] In one embodiment, a light emitting device comprises a
lightguide with light redirecting elements disposed on or within
the lightguide and light extraction features disposed in a
predetermined relationship relative to one or more light
redirecting elements. In another embodiment, a first portion of the
light redirecting elements are disposed above a light extraction
feature in a direction substantially perpendicular to the light
emitting surface, lightguide, or lightguide region. In a further
embodiment, light redirecting elements are disposed to redirect
light which was redirected from a light extraction feature such
that the light exiting the light redirecting elements is one
selected from the group: more collimated than a similar lightguide
with a substantially planar surface; has a full angular width at
half maximum intensity less than 60 degrees, 50 degrees, 40
degrees, 30 degrees, 20 degrees, 10 degrees, or 5 degrees in a
first light output plane; has a full angular width at half maximum
intensity less than 60 degrees, 50 degrees, 40 degrees, 30 degrees,
20 degrees, 10 degrees, or 5 degrees in a first light output plane
and second light output plane orthogonal to the first output plane;
and has a full angular width at half maximum intensity less than 60
degrees, 50 degrees, 40 degrees, 30 degrees, 20 degrees, 10
degrees, or 5 degrees in all planes parallel to the optical axis of
the light emitting device.
[0389] In one embodiment, the lightguide comprises a substantially
linear array of lenticules disposed on at least one surface
opposite a substantially linear array of light extraction features
wherein the light redirecting element collimates a first portion of
the light extracted from the lightguide by the light extraction
features. In a further embodiment, a light emitting device
comprises a lenticular lens film lightguide further comprising
coupling lightguides, wherein the coupling lightguides are disposed
substantially parallel to the lenticules at the lightguide region
or light mixing region and the lenticular lens film further
comprises linear regions of light reflecting ink light extraction
features disposed substantially opposite the lenticules on the
opposite surface of the lenticular lens film lightguide and the
light exiting the light emitting device is collimated. In a further
embodiment, the light extraction features are light redirecting
features (such as TIR grooves or linear diffraction gratings) that
redirect light incident within one plane significantly more than
light incident from a plane orthogonal to the first. In one
embodiment, a lenticular lens film comprises grooves on the
opposite surface of the lenticules oriented at a first angle
greater than 0 degrees to the lenticules.
[0390] In another embodiment, a light emitting device comprises a
microlens array film lightguide with an array of microlenses on one
surface and the film further comprises regions of reflecting ink
light extraction features disposed substantially opposite the
microlenses on the opposite surface of the lenticular lens film
lightguide and the light exiting the light emitting device is
substantially collimated or has an angular FWHM luminous intensity
less than 60 degrees. A microlens array film, for example can
collimate light from the light extraction features in radially
symmetric directions. In one embodiment, the microlens array film
is separated from the lightguide by an air gap.
[0391] The width of the light extraction features (reflecting line
of ink in the aforementioned lenticular lens lightguide film
embodiment) will contribute to the degree of collimation of the
light exiting the light emitting device. In one embodiment, light
redirecting elements are disposed substantially opposite light
extraction features and the average width of the light extraction
features in first direction divided by the average width in a first
direction of the light redirecting elements is less than one
selected from the group: 1, 0.9, 0.7, 0.5, 0.4, 0.3, 0.2, and 0.1.
In a further embodiment, the focal point of collimated visible
light incident on a light redirecting element in a direction
opposite from the surface comprising the light extraction feature
is within at most one selected from the group: 5%, 10%, 20%, 30%,
40%, 50% and 60% of the width of light redirecting element from the
light extraction feature. In another embodiment, the focal length
of at least one light redirecting element or the average focal
length of the light redirecting elements when illuminated by
collimated light from the direction opposite the lightguide is less
than one selected from the group: 1 millimeter, 500 microns, 300
microns, 200 microns, 100 microns, 75 microns, 50 microns and 25
microns.
[0392] In one embodiment, the focal length of the light redirecting
element divided by the width of the light redirecting element is
less than one selected from the group: 3, 2, 1.5, 1, 0.8, and 0.6.
In another embodiment, the f# of the light redirecting elements is
less than one selected from the group: 3, 2, 1.5, 1, 0.8, and 0.6.
In another embodiment, the light redirecting element is a linear
Fresnel lens array with a cross-section of refractive Fresnel
structures. In another embodiment, the light redirecting element is
a linear Fresnel-TIR hybrid lens array with a cross-section of
refractive Fresnel structures and totally internally reflective
structures.
[0393] In a further embodiment, light redirecting elements are
disposed to redirect light which was redirected from a light
extraction feature such that a portion of the light exiting the
light redirecting elements is redirected with an optical axis at an
angle greater than 0 degrees from the direction perpendicular to
the light emitting region, lightguide region, lightguide, or light
emitting surface. In another embodiment, the light redirecting
elements are disposed to redirect light which was redirected from a
light extraction feature such that the light exiting the light
redirecting elements is redirected to an optical axis substantially
parallel to the direction perpendicular to the light emitting
region, lightguide region, lightguide, or light emitting surface.
In a further embodiment, the light redirecting element decreases
the full angular width at half maximum intensity of the light
incident on a region of the light redirecting element and redirects
the optical axis of the light incident to a region of the light
redirecting element at a first angle to a second angle different
than the first.
[0394] In another embodiment, the angular spread of the light
redirected by the light extraction feature is controlled to
optimize a light control factor. One light control factor is the
percentage of light reaching a neighboring light redirecting
element which could redirect light into an undesirable angle. This
could cause side-lobes or light output into undesirable areas. For
example, a strongly diffusively reflective scattering light
extraction feature disposed directly beneath a lenticule in a
lenticular lens array may scatter light into a neighboring
lenticule such that there is a side lobe of light at higher angular
intensity which is undesirable in an application desiring
collimated light output. Similarly a light extraction feature which
redirects light into a large angular rage such as a hemispherical
dome with a relatively small radius of curvature may also redirect
light into neighboring lenticules and create side-lobes. In one
embodiment, the Bidirectional Scattering Distribution Function
(BSDF) of the light extraction feature is controlled to direct a
first portion of incident light within a first angular range into a
second angular range into the light redirecting element to create a
predetermined third angular range of light exiting the light
emitting device.
Off-Axis Light Redirection
[0395] In a further embodiment, at least one light extraction
feature is centered in a first plane off-axis from the axis of the
light redirecting element. In this embodiment, a portion of the
light extraction feature may intersect the optical axis of the
light extraction feature or it may be disposed sufficiently far
from the optical axis that it does not intersect the optical axis
of the light extraction feature. In another embodiment, the
distance between the centers of the light extraction features and
the corresponding light redirecting elements in first plane varies
across the array or arrangement of light redirecting elements.
[0396] In one embodiment, the locations of the light extraction
features relative to the locations of the corresponding light
redirecting elements varies in at least a first plane and the
optical axis of the light emitted from different regions of the
light emitting surface varies relative to the orientation of the
light redirecting elements. In this embodiment, for example, light
from two different regions of a planar light emitting surface can
be directed in two different directions. In another example of this
embodiment, light from two different regions (the bottom and side
regions, for example) of a light fixture with a convex curved light
emitting surface directed downwards is directed in the same
direction (the optical axes of each region are directed downwards
toward the nadir wherein the optical axis of the light redirecting
elements in the bottom region are substantially parallel to the
nadir, and the optical axis of the light redirecting elements in
the side region are at an angle, such as 45 degrees, from the
nadir). In another embodiment, the location of the light extraction
features are further from the optical axes of the corresponding
light redirecting elements in the outer regions of the light
emitting surface in a direction perpendicular to lenticules than
the central regions where the light extraction regions are
substantially on-axis and the light emitted from the light emitting
device is more collimated. Similarly, if the light extraction
features are located further from the optical axes of the light
redirecting elements in a direction orthogonal to the lenticules
from a first edge of a light emitting surface, the light emitted
from the light emitting surface can be directed substantially
off-axis. Other combinations of locations of light extraction
features relative to light redirecting elements can readily be
envisioned including varying the distance of the light extraction
features from the optical axis of the light redirecting element in
a nonlinear fashion, moving closer to the axis then further from
the axis then closer to the axis in a first direction, moving
further from the axis then closer to the axis then further to the
axis in a first direction, upper and lower apexes of curved regions
of a light emitting surface with a sinusoidal-like cross-sectional
(wave-like) profile having light extraction features substantially
on-axis and the walls of the profile having light extraction
features further from the optical axis of the light redirecting
elements, regular or irregular variations in separation distances
of the light extraction features from the optical axes of the light
redirecting elements, etc.
Angular Width Control
[0397] In one embodiment, the widths of the light extraction
features relative to the corresponding widths of the light
redirecting elements varies in at least a first plane and the full
angular width at half maximum intensity of the light emitted from
the light redirecting elements varies in at least a first plane.
For example, in one embodiment, a light emitting device comprises a
lenticular lens array lightguide film wherein the central region of
the light emitting surface in a direction perpendicular to the
lenticules comprises light extraction features that have an average
width of approximately 20% of the average width of the lenticules
and the outer region of the light emitting surface in a direction
perpendicular to the lenticules comprises light extraction features
with an average width of approximately 5% of the average width of
the lenticules and the angular full width at half maximum intensity
of the light emitted from the central region is larger than that
from the outer regions.
Off-Axis and Angular Width Control
[0398] In one embodiment, the locations and widths of the light
extraction features relative to is the corresponding locations and
widths, respectively, of the light redirecting elements varies in
at least a first plane and the full angular width at half maximum
intensity of the light emitted from the light redirecting elements
and the optical axis of the light emitted from different regions of
the light emitting surface varies in at least a first plane. By
controlling the relative widths and locations of the light
extraction features, the direction and angular width of the light
emitted from the light emitting device can be varied and controlled
to achieve desired light output profiles.
Light Redirecting Element
[0399] As used herein, the light redirecting element is an optical
element which redirects a portion of light of a first wavelength
range incident in a first angular range into a second angular range
different than the first, in one embodiment, the light redirecting
element comprises at least one element selected from the group:
refractive features, totally internally reflected feature,
reflective surface, prismatic surface, microlens surface,
diffractive feature, holographic feature, diffraction grating,
surface feature, volumetric feature, and lens. In a further
embodiment, the light redirecting element comprises a plurality of
the aforementioned elements. The plurality of elements may be in
the form of a 2-D array (such as a grid of microlenses or
close-packed array of microlenses), a one-dimensional array (such
as a lenticular lens array), random arrangement, predetermined
non-regular spacing, semi-random arrangement, or other
predetermined arrangement. The elements may comprise different
features, with different surface or volumetric features or
interfaces and may be disposed at different thicknesses within the
volume of the light redirecting element, lightguide, or lightguide
region. The individual elements may vary in the x, y, or z
direction by at least one selected from the group: height, width,
thickness, position, angle, radius of curvature, pitch,
orientation, spacing, cross-sectional profile, and location in the
x, y, or z axis.
[0400] In one embodiment, the light redirecting element is
optically coupled to the lightguide in at least one region. In
another embodiment, the light redirecting element, film, or layer
comprising the light redirecting element is separated in a
direction perpendicular to the lightguide, lightguide region, or
light emitting surface of the lightguide by an air gap. In a father
embodiment, the lightguide, lightguide region, or light emitting
surface of the lightguide is disposed substantially between two or
more light redirecting elements. In another embodiment, a cladding
layer or region is disposed between the lightguide or lightguide
region and the light redirecting element. In another embodiment,
the lightguide or lightguide region is disposed between two light
redirecting elements wherein light is extracted from the lightguide
or lightguide region from both sides and redirected by light
redirecting elements. In this embodiment, a backlight may be
designed to emit light in opposite directions to illuminate two
displays, or the light emitting device could be designed to emit
light from one side of the lightguide by adding a reflective
element to reflect light emitted out of the lightguide in the
opposite direction back through the lightguide and out the other
side.
[0401] In another embodiment, the average or maximum dimension of
an element of a light redirecting element in at least one output
plane of the light redirecting element is equal to or less than one
selected from the group: 100%, 90%, 80%, 70%, 60%, 50%, 40%, 30%,
20%, and 10% the average or maximum dimension of a pixel or
sub-pixel of a spatial light modulator or display. In another
embodiment, a backlight comprises light redirecting elements that
redirect light to within a MEM of 30 degrees toward a display
wherein each pixel or sub-pixel of the display receives light from
two or more light redirecting elements.
[0402] In a further embodiment, the light redirecting element is
disposed to receive light from an electro-optical element wherein
the optical properties may be changed in one or more regions,
selectively or as a whole by applying a voltage or current to the
device. In one embodiment, the light extraction features are
regions of a polymer dispersed liquid crystal material wherein the
light scattering from the lightguide in a diffuse state is
redirected by the light redirecting element, in another embodiment,
the light extraction feature has a small passive region and a
larger active region disposed to change from substantially clear to
substantially transmissive diffuse (forward scattering) such that
when used in conjunction with the light redirecting element, the
display can be changed from a narrow viewing angle display to a
larger viewing angle display through the application or removal of
voltage or current from the electro-optical region or material. For
example, lines of grooved light extraction features are disposed
adjacent (x, y, or z direction) a film comprising wider lines
polymer dispersed liquid crystal (PDLC) material disposed to change
from substantially clear to substantially diffuse upon application
of a voltage across the electrodes. Other electro-optical materials
such as electrophoretic, electro-wetting, electrochromic, liquid
crystal, electroactive, MEMS devices, smart materials and other
materials that can change their optical properties through
application of a voltage, current, or electromagnetic field may
also be used.
[0403] In another embodiment, the light redirecting element is a
collection of prisms disposed to refract and totally internally
reflect light toward the spatial light modulator. In one
embodiment, the collection of prisms is a linear array of prisms
with an apex angle between 50 degrees and 70 degrees. In another
embodiment, the collection of prisms is a linear array of prisms
with an apex angle between 50 degrees and 70 degrees to which a
light transmitting material has been applied or disposed between
the prisms and the lightguide or lightguide region within regions
such that the film is effectively planarized in these regions and
the collection of prisms is now two-dimensionally varying
arrangement of prisms (thus on the surface it no longer appears to
be a linear array). Other forms of light redirecting elements,
reverse prisms, hybrid elements, with refractive or totally
internally reflective features, or a combination thereof, may be
used in an embodiment. Modifications of elements such as
"wave-like" variations, variations in size, dimensions, shapes,
spacing, pitch, curvature, orientation and structures in the x, y,
or z direction, combining curved and straight sections, etc. are
known in the art. Such elements are known in the area of backlights
and optical films for displays and include those disclosed in
"Optical film to enhance cosmetic appearance and brightness in
liquid crystal displays," Lee et al., OPTICS EXPRESS, 9 Jul. 2007,
Vol. 15, No. 14, pp. 8609-8618; "Hybrid normal-reverse prism
coupler for light-emitting diode backlight systems," Aoyama et al.,
APPLIED OPTICS, 1 Oct. 2006, Vol. 45, No. 28, pp. 7273-7278;
Japanese Patent Application No. 2001190876, "Optical Sheet,"
Kamikita Masakazu; U.S. patent application Ser. No. 11/743,159; and
U.S. Pat. Nos. 7,085,060, 6,545,827, 5,594,830, 6,151,169,
6,746,130, and 5,126,882.
Backlight or Frontlight
[0404] In one embodiment, a light emitting display backlight or
frontlight comprises a light source, a light input coupler, and a
lightguide. In one embodiment, the frontlight or backlight
illuminates a display or spatial light modulator selected from the
group: liquid crystal displays (LCD's), MEMs based display,
electrophoretic displays, cholesteric display, time-multiplexed
optical shutter display, color sequential display, interferometric
modulator display, bistable display, electronic paper display, LED
display, TFT display, OLED display, carbon nanotube display,
nanocrystal display, head mounted display, head-up display,
segmented display, passive matrix display, active matrix display,
twisted nemtatic display, in-plane switching display, advanced
fringe field switching display, vertical alignment display, blue
phase mode display, zenithal bistable device, reflective LCD,
transmissive LCD, electrostatic display, electrowetting display,
bistable TN displays, micro-cup EPD displays, grating aligned
zenithal display, photonic crystal display, electrofluidic display,
and electrochromic displays.
LCD Backlight or Frontlight
[0405] In one embodiment, a backlight or frontlight suitable for
use with a liquid crystal display panel comprises at least one
light source, light input coupler, and lightguide. In one
embodiment, the backlight or frontlight comprises a single
lightguide wherein the illumination of the liquid crystal panel is
white. In another embodiment, the backlight or frontlight comprises
a plurality of lightguides disposed to receive light from at least
two light sources with two different color spectra such that they
emit light of two different colors. In another embodiment, the
backlight or frontlight comprises a single lightguide disposed to
receive light from at least two light sources with two different
color spectra such that they emit light of two different colors. In
another embodiment, the backlight or frontlight comprises a single
lightguide disposed to receive light from a red, green and blue
light source. In one embodiment, the lightguide comprises a
plurality of light input couplers wherein the light input couplers
emit light into the lightguide with different wavelength spectrums
or colors. In another embodiment, light sources emitting light of
two different colors or wavelength spectrums are disposed to couple
light into a single light input coupler. In this embodiment, more
than one light input coupler may be used and the color may be
controlled directly by modulating the light sources.
[0406] In a further embodiment, the backlight or frontlight
comprises a lightguide disposed to receive light from a blue or UV
light emitting source and further comprises a region comprising a
wavelength conversion material such as a phosphor film. In another
embodiment, the backlight comprises 3 layers of film lightguides
wherein each lightguide illuminates a display with substantially
uniform luminance when the corresponding light source is turned on.
In this embodiment, the color gamut can be increased by reducing
the requirements of the color filters and the display can operate
in a color sequential mode or all-colors-on simultaneously mode. In
a further embodiment, the backlight or frontlight comprises 3
layers of film lightguides with 3 spatially distinct light emitting
regions comprising light extraction features wherein each light
extraction region for a particular lightguide corresponds to a set
of color pixels in the display. In this embodiment, by registering
the light extracting features (or regions) to the corresponding
red, green, and blue pixels (for example) in a display panel, the
color filters are not necessarily needed and the display is more
efficient. In this embodiment, color filters may be used, however,
to reduce crosstalk.
[0407] In a further embodiment, the light emitting device comprises
a plurality of lightguides (such as a red, green and blue
lightguide) disposed to receive light from a plurality of light
sources emitting light with different wavelength spectrums (and
thus different colored light) and emit the light from substantially
different regions corresponding to different colored sub-pixels of
a spatial light modulator (such as an LCD panel), and further
comprises a plurality of light redirecting elements disposed to
redirect light from the lightguides towards the spatial light
modulator. For example, each lightguide may comprise a cladding
region between the lightguide and the spatial light modulator
wherein light redirecting elements such as microlenses are disposed
between the light extraction features on the lightguide and the
spatial light modulator and direct the light toward the spatial
light modulator with a FWHM of less than 60 degrees, a FWHM of less
than 30 degrees, an optical axis of emitted light within 50 degrees
from the normal to the spatial light modulator output surface, an
optical axis of emitted light within 30 degrees from the normal to
the spatial light modulator output surface, or an optical axis of
emitted light within 10 degrees from the normal to the spatial
light modulator output surface. In a further embodiment, an
arrangement of light redirecting elements are disposed within a
region disposed between the plurality of lightguides and the
spatial light modulator to reduce the FWHM of the light emitted
from the plurality of lightguides. The light redirecting elements
arranged within a region, such as on the surface of a film layer,
may have similar or dissimilar light redirecting features. In one
embodiment, the light redirecting elements are designed to redirect
light from light extraction features from a plurality of
lightguides into FWHM angles or optical axes within 10 degrees of
each other. For example, a backlight comprising a red, green, and
blue film-based lightguides may comprise an array of microlenses
with different focal lengths substantially near the 3 depths of the
light extraction features on the 3 lightguides. In one embodiment,
lightguide films less than 100 microns thick enable light
redirecting elements to be closer to the light extraction features
on the lightguide and therefore capture more light from the light
extraction feature. In another embodiment, a light redirecting
element such as a microlens array with substantially the same light
redirection features (such as the same radius of curvature) may be
used with thin lightguides with light extraction features at
different depths since the distance between the nearest
corresponding light extraction feature and farthest corresponding
light extraction feature in the thickness direction is small
relative to the diameter (or a dimension) of the light redirecting
element, pixel, or sub-pixel.
[0408] In one embodiment a color sequential display comprises at
least one light source, light input coupler, lightguide and a
display panel wherein the panel has a refresh rate faster than one
selected from the group: 150 hz, 230 hz, 270 hz, 350 hz, 410 hz,
470 hz, 530 hz, 590 hz, 650 hz, and 710 hz.
[0409] In another embodiment, a backlight or frontlight comprises
at least one light source, light input coupler, and lightguide
wherein lightguide comprises core regions that are substantially
thinner than the film and are printed onto a film such that the
color or flux of the light reaching light extracting regions can be
controlled.
[0410] In another embodiment, a backlight or frontlight comprises
at least one light source, light input coupler, and lightguide
wherein lightguide forms a substrate or protective region within
the display panel. In one embodiment, the lightguide is the
substrate for the liquid crystal display. In a further embodiment,
the lightguide is optically coupled to an outer surface of the
display, is disposed within the display, within the liquid crystal
cell, or between two substrates of the display.
[0411] In another embodiment, a backlight or frontlight comprises
at least one light source and a light input coupler comprising at
least one coupling lightguide optically coupled to at least one
display component (such as a substrate, film, glass, polymer or
other layer of a liquid crystal based display or other display)
wherein the component guides light received from the at least one
coupling lightguide in a waveguide condition. By optically coupling
the coupling lightguides to a display component such as an LCD
glass substrate for example, the component can function as the
lightguide and alleviate the need for additional backlighting films
or components.
[0412] In another embodiment, a light emitting device comprises
more than one lightguide or lightguide region to provide redundancy
of light output in case of difficulties with one backlight or for
increased light output. In military and critical display
applications (surgery rooms) one often desires to have redundancy
in case of electrical or light source or other component failure.
The reduced thickness of the film-based lightguide in embodiments
allow for one or more additional backlights which may include more
than one additional light source and driver and electronic control
circuitry. In a further embodiment, one or more photodetectors such
as silicon photodiodes or LEDs used in "reverse mode" detects the
light intensity (or color) of the light within a region to
determine if the redundant lightguide, color compensation
lightguide, or high brightness backlight lightguide should be
turned on. In another embodiment, multiple LEDs driven from the
same or different circuits may be used at the same or different
light input couplers to provide redundancy (or color compensation,
or high brightness mode) within a single light input coupler or
redundancy through multiple light input couplers within the same
lightguide. When using multiple light input couplers on the same
lightguide, the couplers may be arranged on the same side, the
opposite side, an orthogonal side, or at an edge different to the
first light input coupler.
Modes of the Light Emitting Device
[0413] In another embodiment, a light emitting device comprises one
or more modes selected from the group: normal viewing mode, daytime
viewing mode, high brightness mode, low brightness mode, nighttime
viewing mode, night vision or NVIS compatible mode, dual display
mode, monochrome mode, grayscale mode, transparent mode, full color
mode, high color gamut mode, color corrected mode, redundant mode,
touchscreen mode, 3D mode, field sequential color mode, privacy
mode, video display mode, photo display mode, alarm mode,
nightlight mode, emergency lighting/sign mode. The daytime viewing
mode may include driving the device (such as a display or light
fixture) at a high brightness (greater than 300 Cd/m2 for example)
and may include using two or more lightguides, two or more light
input couplers, or driving additional LEDs at one or more light
input couplers to produce the increase in brightness. The nighttime
viewing mode may include driving the device at a low brightness
(less than 50 Cd/m2 for example). The dual display mode may
comprise a backlight wherein the lightguide illuminates more than
one spatial light modulator or display. For example, in a cellphone
where there are two displays in a flip configuration, each display
can be illuminated by the same film lightguide that emits light
toward each display. In a transparent mode, the lightguide may be
designed to be substantially transparent such that one can see
through the display or backlight. In another embodiment, the light
emitting device comprises at least one lightguide for a first mode,
and a second backlight for a second mode different than the first
mode. For example, the transparent mode backlight lightguide on a
device may have a lower light extraction feature density, yet
enable see-through. For a high brightness mode on the same device,
a second lightguide may provide increased display luminance
relative to the transparent mode. The increased color gamut mode,
may provide an increased color gamut (such as greater than 100%
NTSC) by using one or more spectrally narrow colored LEDs or light
sources. These LEDs used in the high color gamut mode may provide
increased color gamut by illumination through the same or different
lightguide or light input coupler. The color corrected mode may
compensate for light source color variation over time (such as
phosphor variation), LED color binning differences, or due to
temperature or the environment. The touchscreen mode may allow one
or more lightguides to operate as an optical frustrated TIR based
touchscreen. The redundant backlight mode may comprise one or more
lightguides or light sources that can operate upon failure or other
need. The 3D mode for the light emitting device may comprise a
display and light redirecting elements or a display and
polarization based, LC shutter based, or spectrally selective based
glasses to enable stereoscopic display. The mode may, for example,
comprise one or more separate film-based backlight lightguide for
3D mode or a film-based lightguide and a display configured to
display images stereoscopically. The privacy mode, for example, may
comprise a switchable region of a polymer dispersed liquid crystal
disposed beneath a light redirecting element to increase or
decrease the viewing angle by switching to a substantially diffuse
mode, or substantially clear mode, respectively. In another
embodiment, the light emitting device further comprises a video
display mode or a photo display mode wherein the color gamut is
increased in the mode. In a further embodiment, the light emitting
device comprises an alarm mode wherein one or more lightguides is
turned on to draw attention to a region or a display. For example,
when a cellphone is ringing, the lightguide that is formed around
or on a portion of the exterior of the cellphone may be illuminated
to "light up" the phone when it is ringing. By using a film-based
lightguide, the lightguide film may be formed into a phone housing
(thermoforming for example) or it may be film-insert molded to the
interior (translucent or transparent housing) or exterior of the
housing. In another embodiment, the light emitting device has an
emergency mode wherein at least one lightguide is illuminated to
provide notification (such as displaying the illuminated word
"EXIT") or illumination (such as emergency lighting for a hallway).
The illumination in one or more modes may be a different color to
provide increased visibility through smoke (red for example).
NVIS Compatible Mode
[0414] The night vision or NVIS mode may include illuminating one
or more lightguides, two or more light input couplers, or driving
additional LEDs at one or more light input couplers to produce the
desired luminance and spectral output. In this mode, the spectrum
of the LEDs for an NVIS mode may be compatible with US Military
specifications MIL-STD-3009, for example. In applications requiring
an NVIS compatible mode, a combination of LEDs or other light
sources with different colors may be used to achieve the desired
color and compatibility in a daytime mode and nighttime mode. For
example, a daytime mode may incorporate white LEDs and blue LEDs,
and a nighttime or NVIS mode may incorporate white, red, and blue
LEDs where the relative output of one or more of the LEDs can be
controlled. These white or colored LEDs may be disposed on the same
light input coupler or different light input couplers, the same
lightguide or different lightguides, on the same side of the
lightguide, or on a different side of the lightguide. Thus, each
lightguide may comprise a single color or a mixture of colors and
feedback mechanisms (such as photodiodes or LEDs used in reverse
mode) may be used to control the relative output or compensate for
color variation over time or background (ambient) lighting
conditions. The light emitting device may further comprise an NVIS
compatible filter to minimize undesired light output, such as a
white film-based backlight lightguide with a multilayer dielectric
NVIS compatible filter where the white lightguide is illuminated by
white LEDs or white LEDs and Red LEDs, in a further embodiment, a
backlight comprises one or more lightguides illuminated by light
from one or more LEDs of color selected from the group: red, green,
blue, warm white, cool white, yellow, and amber. In another
embodiment, the aforementioned backlight further comprises a NVIS
compatible filter disposed between the backlight or lightguide and
a liquid crystal display.
Field Sequential Color Mode
[0415] In a further embodiment, a backlight or frontlight comprises
a lightguide comprising light extraction features and a light
redirecting element disposed to receive a portion of the light
extracted from the lightguide and direct a portion of this light
into a predetermined angular range. In another embodiment, the
light redirecting element substantially collimates, reduces the
angular full-width at half maximum intensity to 60 degrees, reduces
the angular full-width at half maximum intensity to 30 degrees,
reduces the angular full-width at half maximum intensity to 20
degrees, or reduces the angular full-width at half maximum
intensity to 10 degrees, a portion of light from the lightguide and
reduces the percentage of cross-talk light from one light
extraction region reaching an undesired neighboring pixel,
sub-pixel, or color filter. When the relative positions of the
light extraction features, light redirecting elements, and pixels,
sub-pixels, or color filters are controlled then light from a
predetermined light extraction feature can be controlled such that
there is little leakage of light into a neighboring pixel,
sub-pixel, or color filter. This can be useful in a backlight or
frontlight such as a color sequential backlight wherein three
lightguides (one for red, green, and blue) extract light in a
pattern such that color filters are not needed (or color filters
are included and the color quality, contrast or gamut is increased)
since the light is substantially collimated and no light or a small
percentage of light extracted from the lightguide by a light
extraction feature on the red lightguide beneath a pixel
corresponding to a red pixel will be directed into the neighboring
blue pixel.
Stereoscopic Display Mode
[0416] In another embodiment, a display capable of operating in
stereoscopic display mode comprises a backlight or frontlight
wherein at least one lightguide or light extracting region is
disposed within or on top of a film-based lightguide wherein at
least two sets of light emitting regions can be separately
controlled to produce at least two sets of images in conjunction
with a stereoscopic display. The 3D display may further comprise
light redirecting elements, parallax barriers, lenticular elements,
or other optical components to effectively convert the spatially
separated light regions into angularly separated light regions
either before or after spatially modulating the light.
[0417] In a further embodiment, a light emitting device comprises
at least one first lightguide emitting light in a first angular
range and at least one second lightguide emitting light in a second
angular range. By employing lightguides emitting lightguides
emitting light into two different angular ranges, viewing angle
dependent properties such as dual view display or stereoscopic
display or backlight can be created. In one embodiment, the first
lightguide emits light with an optical axis substantially near +45
degrees from the normal to the light output surface and the second
lightguide emits light with an optical axis substantially near 45
degrees from the normal to the light output surface. For example, a
display used in an automobile display dash between the driver and
passenger may display different information to each person, or the
display may more efficiently direct light toward the two viewers
and not waste light by directing it out normal to the surface. In a
further embodiment, the first lightguide emits light corresponding
to light illuminating first regions of a display (or a first time
period of the display) corresponding to a left image and the second
lightguide emits light corresponding to light illuminating second
regions of a display (or a second time period of the display)
corresponding to a right image such that the display is a
stereoscopic 3D display.
[0418] In one embodiment, the first lightguide emits substantially
white light in a first angular direction from a first set of light
extraction features and a second light guide beneath the first
lightguide emits substantially white light in a second angular
direction from a second set of light extraction features. In
another embodiment, the first set of light extraction features are
disposed beneath a first set of pixels corresponding to a left
display image and the second set of light extraction features are
substantially spatially separated from the first and disposed
beneath a second set of pixels corresponding to a right display
image and the display is autostereoscopic. In a further embodiment,
the aforementioned autostereoscopic display further comprises a
third lightguide emitting light toward the first and second sets of
pixels and is illuminated in a 2D display mode display full
resolution.
Field Sequential Color & Stereoscopic Mode
[0419] One or more lightguides may be illuminated by red, green,
and blue (and optionally other colors for increased color gamut
such as yellow) light which may illuminate a spatial light
modulator in a Field Sequential Color (FSC) or Color Sequential
(CS) mode. In addition, the display may be driven in a fast mode
such that when synchronized with liquid crystal based shutter
glasses, the display appears 3D through stereoscopic display. Other
methods such as passive polarizer (linear or circular) based
viewing glasses and interference filter spectrally selective 3D
methods (such as used by Dolby 3D) may also be employed with a
field sequential color based backlight comprising a film-based
lightguide. In another embodiment, the lightguides may be driven
sequentially or the light sources illuminating separate lightguides
may be driven sequentially. In one embodiment, one or more light
sources illuminating a first lightguide are pulsed on, followed by
pulsing on one or more light sources illuminating a second
lightguide, then pulsing one or more light sources in the first
lightguide. Multiple lightguides, spatial regions of one or more
lightguides, or spectrally selected elements within the lightguides
may be used in a color sequential display to increase the color
gamut, decrease the percentage of light absorbed by the color
filters, or eliminate the color filters. In another embodiment, two
separate lightguides are illuminated with red, green, and blue
light and the lightguides have two spatially separate regions
comprising light extraction features wherein the light emitting
device further comprises a light redirecting element which
redirects light from the first lightguide into a first angular
range corresponding to the left image and further redirects light
from the second lightguide into a second angular range
corresponding to the right image and a liquid crystal panel driven
to display stereoscopic information in a spatial configuration and
the display is a autostereoscopic 3D display. In a further
embodiment, two separate lightguides are illuminated with red,
green and blue light and the lightguides have two spatially
separate or overlapping regions comprising light extraction
features wherein the light emitting device further comprises a
liquid crystal panel driven at a frequency higher than 100 hz to
display stereoscopic information such that a stereoscopic display
is visible with liquid crystal shutter based glasses. In a further
embodiment, the red, green, and blue light emitted from the first
backlight have wavelength spectrums R1, G1, and B1, respectively,
and the red, green, and blue light emitted from the second
backlight have wavelength spectrums R2, G2, and B2, respectively
and R1 does not substantially overlap R2, G1 does not substantially
overlap G2, and B1 does not substantially overlap B2, and
spectrally selective viewing glasses may be used to view the
display in stereoscopic 3D such as those disclosed in embodiments
of stereoscopic viewing systems in U.S. Pat. Application Nos.
US20090316114, US20100013911, US20100067108, US20100066976,
US20100073769, and US2010006085.
[0420] Table 1 illustrates examples of embodiments comprising one
or more lightguides, one or more colored sources, 3D driving
techniques and pixel arrangements for 2D and 3D displays.
TABLE-US-00001 TABLE 1 Example modes for driving 2D & 3D
displays under embodiments. Two Light extraction feature Angular
Pixel Color Panel drive Shutter 2D/3D Light source modulation
Lightguides pattern outputs Arrangement Filters scheme Glasses
modes Continuous 1 White Standard No Standard Yes Standard No 2D
Continuous 1 White Standard No Standard Yes Left then right Yes 2D
+ 3D image Continuous 2 White Spatially separate L&R Yes
Standard + Yes Standard + 3D No 2D + 3D (L&R images) spatial
mode Continuous 1 R + G + B Standard No Standard Yes Standard No 2D
Continuous 1 R + G + B Standard No Standard Yes Left then right Yes
image Continuous 2 x R + G + B Spatially separate L&R Yes
Standard + Yes Standard + 3D No 2D + 3D (L&R images) spatial
mode Continuous 3 (R, G, & B) Standard No Standard Yes Standard
No 2D Continuous 3 (R, G, & B) Standard No Standard Yes Left
then right Yes 2D + 3D image Continuous 3 (R, G, & B) Separate
regions for No Standard None Standard No 2D R, G, & B
Continuous 3 (R, G, & B) Separate regions for No Standard None
Left then right Yes 2D + 3D R, G, & B image Source Color
Sequential 1 R + G + B Standard No Standard Optional Color Field No
2D Sequential (CFS) Source Color Sequential 1 R + G + B Standard No
Standard Optional CFS + Left then Yes 2D + 3D right image Source
color sequential 3 (R, G, & B) Standard No Standard No Color
Field No 2D Sequential Source color sequential 3 (R, G, & B)
Standard No Standard No CFS + Left then Yes 2D + 3D right image
Source color sequential 3 (R, G, & B) Separate regions for No
Standard Optional Color Field No 2D R, G, & B Sequential Source
color sequential 3 (R, G, & B) Separate regions for No Standard
Optional Left then right Yes 2D + 3D R, G, & B image Lightguide
sequential 2 White Standard or adjacent Yes Standard Yes Left then
right No 2D + 3D patterns image Lightguide Sequential 2 x (R + G +
B) Standard or adjacent Yes Standard Yes Left then right No 2D + 3D
patterns image Lightguide Sequential 2 White Separate regions for
No Standard + Yes Left then right Yes 2D + 3D Left & Right
images L&R image Lightguide Sequential 2 x (R + G + B) Separate
regions for Yes Standard + Yes Left then right Yes 2D + 3D Left
& Right images L&R image R1, R2, G1, G2, B1, B2, 2 x (R + G
+ B) Standard No Standard No Stereoscopic Yes 2D + 3D stereoscopic
CFS color Sequential R1, R2, G1, G2, B1, B2, 2 x (R + G + B)
Separate regions for No Standard + Optional Stereoscopic Yes 2D +
3D stereoscopic Left & Right images L&R CFS color
Sequential R1, R2, G1, G2, B1, B2, 2 x (R + G + B) Separate regions
for Yes Standard + Optional Stereoscopic No 2D + 3D stereoscopic
Left & Right images L&R CFS color Sequential
other displays including Field Sequential Color drive or Color
Sequential drive schemes of one or more embodiments include drive
schemes disclosed in U.S. patent application Ser. No. 12/124,317,
U.S. Pat. Nos. 7,751,663; 7,742,031; 7,742,016; 7,696,968;
7,695,180; 7,692,624; 7,731,371; 7,724,220; 7,728,810; 7,728,514;
and U.S. Pat. Application Publication Nos. US20100164856;
US20100164855; US20100164856; US20100165218; US20100156926;
US20100149435; US20100134393; US20100128050; US20100127959;
US20100118007; US20100117945; US20100117942; US20100110063;
US20100109566; US20100079366; US20100073568; US20100072900;
US20100060556; US20100045707; US20100045579; US20100039425;
US20100039359; US20100039358; US20100019999; and US20100013755.
[0421] In some embodiments shown in Table 1, the display shows
information for one image and subsequently shows information for a
second image (left and right images for example). It is understood
that regions of the display can display portions of the image for
viewing by the left eye while a different region of the display
simultaneously shows images corresponding to the right eye. The
display may provide spatial light modulation corresponding to a
first field of information in a region followed by a second field
of information (such as a first frame followed by a second frame,
progressive scanning, interlaced, etc.). Embodiment include
standard pixel arrangements and 3D backlight and pixel arrangements
such as matrix, RUB Stripes, and PenTile sub-pixel arrangements and
other arrangements such as those disclosed in U.S. Pat. Nos.
6,219,025; 6,239,783; 6,307,566; 6,225,973; 6,243,070; 6,393,145;
6,421,054; 6,282,327; 6,624,828; 7,728,846; 7,689,058; 7,688,335;
7,639,849; 7,598,963; 7,598,961; 7,590,299; 7,589,743; 7,583,279;
7,525,526; 7,511,716; 7,505,053; 7,486,304; 7,471,843; 7,460,133;
7,450,190; 7,427,734; 7,417,601; 7,404,644; 7,396,130; 7,623,141;
7,619,637; and U.S. Pat. Application Publication Nos.
US20100118045; US20100149208 US20100096617; US20100091030;
US20100045695; US20100033494; US20100026709; US20100026704;
US20100013848; US20100007637; US20090303420; US20090278867;
US20090278855; US20090262048; US20090244113; US20090081064;
US20090081063; US20090071734; US20090046108; US20090040207;
US20090033604; US20080284758; US20080278466; US20080266330; and
US20080266329.
[0422] In one embodiment, the light emitting device emits light
toward a display with reflective components such that the
illumination is directed toward the spatial light modulating pixels
from the viewing side of the pixels. In another embodiment, a
display comprises a film-based light emitting device comprising a
light source, light input coupler, and lightguide lighting a
display from the front wherein the light extracting regions of the
lightguide direct light toward an interferometric modulator or IMOD
such as those disclosed in U.S. Pat. Nos. 6,680,792; 7,556,917;
7,532,377 and 7,297,471. The lightguide may be a component external
to the display, an integral component of the display, or optical
coupled to a surface or layer of the display. In one embodiment, a
frontlight comprises a lightguide film comprising a core material
or cladding material that comprises silicone.
[0423] In another embodiment, a display comprises a film-based
light emitting device comprising a light source, light input
coupler, and lightguide lighting a display from the front wherein
the light extracting regions of the lightguide direct light toward
at least one selected from the group: reflective LCD,
electrophoretic display, cholesteric display, zenithal bistable
device, reflective LCD, electrostatic display, electrowetting
display, bistable TN display, micro-cup EPD display, grating
aligned zenithal display, photonic crystal display, electrofluidic
display, and electrochromic displays. In another embodiment, a
display comprises a film-based light emitting device comprising a
light source, light input coupler, and lightguide lighting a
display wherein the light extraction features of the lightguide
direct light toward a time-multiplexed optical shutter display such
as one disclosed in U.S. patent application Ser. Nos. 12/050,045;
12/050,032; 12/050,045; 11/524,704; 12/564,894; 12/574,700;
12/546,601; 11/766,007 and U.S. Pat. Nos. 7,522,354 and
7,450,799.
[0424] In one embodiment, the light emitting device comprises a
reflective spatial light modulator disposed between the lightguide
and the light source for the light emitting device. For example,
the lightguide could be disposed on the front of an electrophoretic
display and at least one selected from the group: lightguide,
lightguide region, light mixing region, and coupling lightguide
could wrap around the electrophoretic display and the light source
could be disposed behind the display.
[0425] In one embodiment, the lightguide serves as an illuminator
for a frustrated total internal reflection type display such as an
optical shutter display that is time-multiplexed by Unipixel Inc.
or a MEMs type display with a movable shutter such as display's by
Pixtronix Inc. or a reflective MEMS based interferometric display
such as those from Qualcomm MEMS Technologies.
[0426] In another embodiment, a display comprises a film-based
light emitting device comprising a light source, light input
coupler, and lightguide illuminating a display or providing a
lightguide for a display to perform light extraction wherein the
display or light emitting device is a type disclosed in U.S. patent
application Ser. Nos. 12/511,693; 12/606,675; 12/221,606;
12/258,206; 12/483,062; 12/221,193; 11/975,411 11/975,398;
10/31/2003; 10/699,397 or U.S. Pat. Nos. 7,586,560; 7,535,611;
6,680,792; 7,556,917; 7,532,377; 7,297,471; 6,680,792, 6,865,641;
6,961,175; 6,980,350; 7,012,726; 7,012,732; 7,035,008; 7,042,643;
7,046,374; 7,060,895; 7,072,093; 7,092,144; 7,110,158; 7,119,945;
7,123,216; 7,130,104; 7,136,213; 7,138,984; 7,142,346; 7,161,094;
7,161,728; 7,161,730; 7,164,520; 7,17,2915, 7,193,768; 7,196,837;
7,198,973; 7,218,438; 7,221,495; 7,221,497; 7,236,284; 7,242,512;
7,242,523; 7,250,315; 7,256,922; 7,259,449; 7,259,865; 7,271,945;
7,280,265; 7,289,256; 7,289,259; 7,291,921; 7,297,471; 7,299,681;
7,302,157; 7,304,784; 7,304,785; 7,304,786; 7,310,179; 7,317,568;
7,321,456; 7,321,457; 7,327,510; 7,333,208; 7,343,080; 7,345,805;
7,345,818; 7,349,136; 7,349,139; 7,349,141; 7,355,779; 7,355,780;
7,359,066; 7,365,897; 7,368,803; 7,369,252; 7,369,292; 7,369,294;
7,369,296; 7,372,613; 7,372,619; 7,373,026; 7,379,227; 7,382,515;
7,385,744; 7,385,748; 7,385,762; 7,388,697; 7,388,704; 7,388,706;
7,403,323; 7,405,852; 7,405,861; 7,405,863; 7,405,924; 7,415,186;
7,417,735; 7,417,782; 7,417,783; 7,417,784; 7,420,725; 7,420,728;
7,423,522; 7,424,198; 7,429,334; 7,446,926; 7,446,927; 7,447,891;
7,450,295; 7,453,579; 7,460,246; 7,460,290; 7,460,291; 7,460,292;
7,470,373; 7,471,442; 7,471,444; 7,476,327; 7,483,197, 7,486,429;
7,486,867; 7,489,428; 7,492,502; 7,492,503; 7,499,208; 7,502,159;
7,515,147; 7,515,327; 7,515,336; 7,517,091; 7,518,775; 7,520,624;
7,525,730; 7,526,103; 7,527,995; 7,527,996; 7,527,998; 7,532,194;
7,532,195; 7,532,377; 7,532,385; 7,534,640; 7,535,621; 7,535,636;
7,542,198; 7,545,550; 7,545,552; 7,545,554; 7,547,565; 7,547,568;
7,550,794; 7,550,810; 7,551,159; 7,551,246; 7,551,344; 7,553,684;
7,554,711; 7,554,714; 7,556,917; 7,556,981; 7,5602,99; 7,561,323;
7,561,334; 7,564,612; 7,564,613; 7,566,664; 7,566,940; 7,567,373;
7,570,865; 7,573,547; 7,576,901; 7,582,952; 7,586,484; 7,601,571;
7,602,375; 7,603,001; 7,612,932; 7,612,933; 7,616,368; 7,616,369;
7,616,781; 7,618,831; 7,619,806; 7,619,809; 7,623,287; 7,623,752;
7,625,825; 7,626,581; 7,626,751; 7,629,197; 7,629,678; 7,6301,14;
7,630,119; 7,630,121; 7,636,151; 7,636,189; 7,642,110; 7,642,127;
7,643,199; 7,643,202; 7,643,203; 7,643,305; 7,646,529; 7,649,671;
7,653,371; 7,660,031; 7,663,794; 7,667,884; 7,668,415; 7,675,665;
7,675,669; 7,679,627; 7,679,812; 7,684,104; 7,684,107; 7,692,839;
7,692,844; 7,701,631; 7,702,192; 7,702,434; 7,704,772; 7,704,773;
7,706,042; 7,706,044; 7,706,050; 7,709,964; 7,710,629; 7,710,632;
7,710,645; 7,711,239; 7,715,079; 7,715,080; 7,715,085; 7,719,500;
7,719,747; and 7,719,752,
Location of the Film-Based Lightguide Frontlight
[0427] In one embodiment, a film-based lightguide frontlight is
disposed between a touchscreen film and a reflective spatial light
modulator. In another embodiment, a touchscreen film is disposed
between the film-based lightguide and the reflective spatial light
modulator. In another embodiment, the reflective spatial light
modulator, the film-based lightguide frontlight and the touchscreen
are all film-based devices and the individual films may be
laminated together. In another embodiment, the light transmitting
electrically conductive coating for the touchscreen device or the
display device is coated onto the film-based lightguide frontlight.
In a further embodiment, the film-based lightguide is physically
coupled to the flexible electrical connectors of the display or the
touchscreen. In one embodiment, the flexible connector is a
"flexible cable", "flex cable," "ribbon cable," or "flexible
harness" comprising a rubber film, polymer film, polyimide film,
polyester film or other suitable film.
[0428] In another embodiment, the film-based lightguide frontlight
comprises at least one of a lightguide region, light mixing region,
coupling lightguide or light input coupler adhered to one or more
flexible connectors and the light input coupler is folded behind
the reflective display. For example, in one embodiment, a flexible
film-based lightguide comprising a polydimethylsiloxane (PDMS) core
and a low refractive index pressure sensitive adhesive cladding is
laminated to a polyimide flexible display connector that connects
the display drivers to the active display area in a reflective
display.
[0429] In one embodiment, a light emitting device comprising a
film-based frontlight and one or more of a light source, coupling
lightguide, non-folded coupling lightguide, input coupler housing,
alignment guide, light source thermal transfer element, and
relative position maintaining element is physically coupled to a
flexible circuit connector or circuit board physically coupled to a
flexible circuit connector for a reflective display, touchscreen,
or frontlight. For example, in one embodiment, a light source for
the film-based lightguide is disposed on and electrically driven
using the same circuit board as the drivers for a reflective
display. In another embodiment, the flexible film-based lightguide
comprises the traces, wires, or other electrical connections for
the display or frontlight, thus enabling one less flexible
connector as the film-based lightguide provides that function. In
another embodiment, a light source for the film-based frontlight is
physically coupled to or shares a common circuit board or flexible
circuit with one or more of the following: a light source driver,
display driver touchscreen driver, microcontroller, additional
light source for an indicator, alignment or registration pins,
alignment guides, alignment or registration holes, openings or
apertures, heat sink, thermal transfer element, metal core
substrate, light collimating optical element, light turning optical
element, bi-directional optical element, light coupling optical
element, secondary optic, light input coupler, plurality of light
input couplers, and light emitting device housing.
[0430] In one embodiment, the film-based lightguide is folded
around a first edge of the active area of a reflective spatial
light modulator behind a reflective spatial light modulator and one
or more selected from the group: touchscreen connector, touchscreen
film substrate, reflective spatial light modulator connector, and
reflective spatial light modulator film substrate is folded behind
the first edge, a second edges substantially orthogonal to the
first edge, or an opposite edge to the first edge. In the
aforementioned embodiment, a portion of the lightguide region,
light mixing region, or coupling lightguide comprises the bend
region of the fold and may extend beyond the reflective spatial
light modulator flexible connector, reflective spatial light
modulator substrate, touchscreen flexible connector or touchscreen
flexible substrate.
[0431] In one embodiment, the film-based lightguide frontlight
comprises two light input couplers disposed along the same or two
different sides of a flexible connector, display substrate film, or
touchscreen. In another embodiment, a display connector or
touchscreen connector is disposed between two light input couplers
of a film-based lightguide frontlight, another embodiment, coupling
lightguides of a film-based frontlight are folded and stacked in an
array, aligned in registration (using pins, cavities, or alignment
guides, for example) with a light source (which may be disposed on
the circuit or connector for a display or touchscreen) and the
film-based lightguide is subsequently laminated to the flexible
connectors and/or the reflective display or touchscreen. In another
embodiment, the film-based lightguide is laminated to the flexible
connectors and/or the reflective display or touchscreen and
subsequently the coupling lightguides of the film-based frontlight
are folded and stacked in an array, and aligned in registration
(using pins, cavities, or alignment guides, for example) with a
light source (which may be disposed on the circuit or connector for
a display or touchscreen). In a further embodiment, the lamination
and registration are performed substantially simultaneously. In a
further embodiment, the light extraction features are formed on (or
within) the film-based lightguide subsequent to laminating (or
adhering) onto the touchscreen or spatial light modulator. In this
embodiment, the registration of light extraction regions (or light
emitting area) of the film-based frontlight (or backlight) with the
spatial light modulator does not need to be performed before or
during lamination because the features can be readily registered
(such as screen printed, etched, scribed, or laser ablated) after
the lamination or adhering process.
Flexible Light Emitting Device, Backlight, or Frontlight
[0432] In another embodiment, a light emitting device such as a
display comprises a film-based light emitting device comprising a
light source, light input coupler, and lightguide wherein the
lightguide, lightguide region, or coupling lightguides can be bent
or folded to radius of curvature of less than 75 times the
thickness of lightguide or lightguide region and function similarly
to similar lightguide or lightguide region that has not been
similarly bent. In another embodiment, the lightguide, coupling
lightguide, or lightguide region can be bent or folded to radius of
curvature greater than 10 times the times the thickness lightguide
or lightguide region and function similarly to similar lightguide
or lightguide region that has not been similarly bent. In another
embodiment, a display comprises a film-based light emitting device
comprising a light source, light input coupler, and lightguide
wherein the display can be bent or folded to radius of curvature of
less than 75 times the thickness of display or lightguide region
and function similarly to similar display that has not been
similarly bent. In another embodiment, the display is capable of
being bent or folded to radius of curvature greater than 10 times
the times the thickness lightguide or lightguide region and
function similarly to similar display that has not been similarly
bent.
[0433] In one embodiment, the light emitting device or a display
incorporating a light emitting device is bent into a substantially
non-planar light emitting device or display incorporating a light
emitting device. In one embodiment, the light emitting device or
display incorporating the light emitting device has a light
emitting surface area substantially in the shape of or comprising a
portion of a shape of at least one selected from the group: a
cylinder, sphere, pyramid, torus, cone, arcuate surface, folded
surface, and bent surface. By folding the input coupler behind the
light emitting region and inside a curved or bent region of the
light emitting device or display, the input coupler can be
effectively "hidden" from view and a substantially seamless display
can be created. In another embodiment, two or more regions of a
light emitting region in a light emitting device overlap each other
in the thickness direction such that there is a continuous light
emitting region such as in the case of a cylindrical display or a
display wrapping around two or more sides of a rectangular
solid.
[0434] In another embodiment, the backlight or frontlight is
incorporated into a portable device such as a cellphone,
smartphone, personal digital assistant, laptop, tablet computer,
pad computer (such as those from Apple Inc.), ebook, e-reader, or
other computing device.
Keypad & Backlight
[0435] In another embodiment, a light emitting device provides
light as a frontlight or backlight of a display and also
illuminates an object. The lightguide, for example, may extend from
the display region to a keypad region for a laptop or cellphone. In
another embodiment, the object of illumination is one or more
selected from the group: a wall or mountable object to which the
display is affixed, the surface of the keys of a keyboard to be
pressed, other buttons, and a second display. In another
embodiment, the light emitting device provides light as a
frontlight or backlight of a display and also provides external
white or color illumination as an illuminating device such as a
light fixture or flashlight.
Lightguide is Also a Touchscreen
[0436] In one embodiment, the lightguide is also a touchscreen for
detecting haptic feedback, contact, proximity, or location of user
input by finger or stylus or other device. In one embodiment, the
lightguide carries at least one selected from the group:
illumination or light modified by the input as well as providing
frontlight, backlight, audio, or other functionality. In one
embodiment, the lightguide is an optical touchscreen. Optical based
touchscreens are known in the art and in one embodiment, the
optical based touchscreen is one disclosed in U.S. patent
application Ser. Nos. 11/826,079, 12/568,931, or 12/250,108. In
another embodiment, the lightguide is an optical touchscreen
suitable for a night vision display or night vision display mode.
In a further embodiment, the lightguide is a night vision
compatible touchscreen as describe in U.S. patent application Ser.
No. 11/826,236.
[0437] In another embodiment, the lightguide is a surface acoustic
wave based touchscreen such as disclosed in U.S. Pat. Nos.
5,784,054, 6,504,530 or U.S. patent application Ser. No.
12/315,690.
Head-up Display
[0438] In another embodiment, a head-up display comprises a
film-based light emitting device comprising a light source, light
input coupler, and lightguide. Head-up displays are used in
automobiles, aircraft and marine craft. In one embodiment, the
lightguide of a head-up display is one selected from the group:
incorporated into a windshield, an integral part of a windshield,
formed with light extracting features before becoming encapsulated
within a windshield, formed with light extracting features after
becoming encapsulated within a windshield, disposed on an inner or
outer surface a windshield, an after-market HUD, a free-standing
HUD suitable for placement on an automobile dashboard, formed where
the lightguide comprises PVB as a core or cladding material.
Small or Substantially Edgeless Light Emitting Device
[0439] In one embodiment, a light emitting device comprises a
border region between a light emitting region and the nearest edge
of the lightguide in a first direction orthogonal to the direction
orthogonal to the light emitting device output surface near the
edge with a region dimension in the first direction less than one
selected from the group: 20 millimeters, 10 millimeters, 5
millimeters, 2 millimeters, 1 millimeters, and 0.5 millimeters. The
border region may be sufficiently small such that the light
emitting device, backlight, frontlight, light fixture, or display
incorporating the light emitting device appears to be edgeless or
substantially without an edge. The light emitting device may have a
small border region along, one, two, three, four or more edges. The
border region may comprise a small frame, bevel, housing, or other
structure or component. In a further embodiment, a light emitting
device comprises a film-based lightguide wherein the light emitting
region extends around the edge of the light emitting device front
surface in a first borderless region such that the light emitting
device does not have a border or frame region in the first
borderless region. For example, in one embodiment, a light emitting
display with a substantially flat viewing surface comprises a
flexible film-based lightguide wherein a first region of a light
emitting region of the lightguide is folded around behind a second
region of the light emitting region such that the light emitting
region extends to the edge and around the edge in at least one
region of the display. By combining the flexible film-based
lightguide with a flexible spatial light modulator such as a
flexible LCD, the display and backlight comprising a film-based
lightguide can bend around a corner or edge of the display.
[0440] In one embodiment, a light emitting device comprises at
least two arrays of coupling lightguides disposed along one edge or
side of a light emitting device wherein the light within the first
array of coupling lightguides is propagating substantially in a
first direction and the light within the second array of coupling
lightguides is propagating substantially in a second direction
oriented greater than 90 degrees from the first direction. In
another embodiment, two light sources are disposed along one side
or side of a light emitting device with their optical axes oriented
in substantially opposite directions to each other such that light
is coupled into two arrays of coupling lightguides and at neither
light source is disposed past the intersection of the edge or side
and the adjacent edge or side of the light emitting device. In a
further embodiment, one light source is disposed along one side of
a light emitting device disposed to emit light in substantially
opposite directions such that light is coupled into two arrays of
coupling lightguides and the light source is not disposed past the
intersection of the edge or side and the adjacent edge or side of
the light emitting device.
[0441] In a further embodiment, the use of one or more light input
couplers disposed to receive light from a light source from a
direction oriented away from the central region of the edge or side
of the light emitting device allows the adjacent side or edge to
have a substantially small or edgeless border region since the
light source does not extend past the neighboring edge or
border.
[0442] In a further embodiment, at least one light input coupler is
folded behind at least one selected from the group: light mixing
region or light emitting region such that the distance between the
edge of the light emitting region and the light emitting device
(the border region) is less than one selected from the group: 20
millimeters, 10 millimeters, 5 millimeters, 2 millimeters, 1
millimeters, and 0.5 millimeters.
[0443] In a further embodiment, a plurality of light input couplers
are folded behind at the light mixing region and light emitting
region such that the distance between the edge of the light
emitting region and the light emitting device (the border region)
along at least two sides or edges of the light emitting device is
less than one selected from the group: 20 millimeters, 10
millimeters, 5 millimeters, 2 millimeters, 1 millimeters, and 0.5
millimeters.
[0444] In a further embodiment, a plurality of light input couplers
are folded behind at least one selected from the group: light
mixing region or light emitting region such that the distance
between the edge of the light emitting region and the light
emitting device (the border region) along all of the sides or edges
of the light emitting device is less than one selected from the
group: 20 millimeters, 10 millimeters, 5 millimeters, 2
millimeters, 1 millimeters, and 0.5 millimeters. In a further
embodiment, selected from the group: the light input surfaces
and/or the coupling lightguides are substantially folded behind at
least one selected from the group: light mixing region and light
emitting region such that the distance between the edge of the
light emitting region and the light emitting device, the border
region, along at least three sides or edges of the light emitting
device is less than one selected from the group: 20 millimeters, 10
millimeters, 5 millimeters, 2 millimeters, 1 millimeters, and 0.5
millimeters.
[0445] In another embodiment, a light emitting device comprises at
least one light input coupler disposed along one edge or side with
the light source disposed within the inner region defined by the
region between the two adjacent edges or sides of the light
emitting device. In this embodiment, the light input coupler may be
a middle input coupler wherein the light source is disposed
substantially in middle region of the inner region.
[0446] In a further embodiment, at least one portion of the array
of coupling lightguides is disposed at a first coupling lightguide
orientation angle to the edge of at least one of the light mixing
region and light emitting region which it directs light into. In
one embodiment, the first coupling lightguide orientation angle is
greater than zero degrees and the border region, along at least one
edge or side of the light emitting device is less than one selected
from the group: 20 millimeters, 10 millimeters, 5 millimeters, 2
millimeters, 1 millimeter, and 0.5 millimeters. In another
embodiment, the coupling lightguides are oriented at an angle along
one side of a light emitting device such that the light source may
be disposed within the inner region of the edge without requiring
more than one bend or fold of the coupling lightguides
[0447] In a further embodiment, a first portion of the border
region between the light emitting region and at least one edge or
side of the light emitting device adjacent the light emitting
region has a transmission greater than 80% and a haze less than
30%. In a further embodiment, a first portion of the border region
between the light emitting region and at least one edge or side of
the light emitting device adjacent the light emitting region has a
transmission greater than 85% and a haze less than 10%. In another
embodiment, the border region between the light emitting region and
at least one edge or side of the light emitting device adjacent the
light emitting region has a transmission greater than 85% and a
haze less than 10%. In another embodiment, the border region
between the light emitting region and at least three edges or sides
of the light emitting device adjacent the light emitting region has
a transmission greater than 85% and a haze less than 10%.
Luminance Uniformity of the Backlight, Frontlight, or Light
Emitting Device
[0448] In one embodiment, a light emitting device comprises a light
source, a light input coupler, and a film-based lightguide wherein
the 9-spot spatial luminance uniformity of the light emitting
surface of the light emitting device measured according to VESA
Flat Panel Display Measurements Standard version 2.0, Jun. 1, 2001
is greater than one selected from the group: 60%, 70%, 80%, 90%,
and 95%. In another embodiment, a display comprises a spatial light
modulator and a light emitting device comprising a light source, a
light input coupler, and a film-based lightguide wherein the 9-spot
spatial luminance uniformity of the light reaching the spatial
light modulator (measured by disposing a white reflectance standard
surface such as Spectralon by Labsphere Inc. in the location where
the spatial light modulator would be located to receive light from
the lightguide and measuring the light reflecting front the
standard surface in 9-spots according to VESA Flat Panel Display
Measurements Standard version 2.0, Jun. 1, 2001) is greater than
one selected from the group: 60%, 70%, 80%, 90%, and 95%. In
another embodiment, a display comprises a spatial light modulator
and a light emitting device comprising a light source, a light
input coupler, and a film-based lightguide wherein the 9-spot
spatial luminance uniformity of the display measured according to
VESA Flat Panel Display
[0449] Measurements Standard version 2.0, Jun. 1, 2001) is greater
than one selected from the group: 60%, 70%, 80%, 90%, and 95%.
Color Uniformity of the of the Backlight, Frontlight, or Light
Emitting Device
[0450] In one embodiment, a light emitting device comprises a light
source, a light input coupler, and a film-based lightguide wherein
the 9-spot sampled spatial color non-uniformity. .DELTA.u'v', of
the light emitting surface of the light emitting device measured on
the 1976 u', v' Uniform Chromaticity Scale as described in VESA.
Flat Panel Display Measurements Standard version 2.0, Jun. 1, 2001
(Appendix 201, page 2.49) is less than one selected from the group:
0.2, 0.1, 0.05, 0.01, and 0.004 when measured using a spectrometer
based spot color meter. In another embodiment, a display comprises
a spatial light modulator and a light emitting device comprising a
light source, a light input coupler, and a film-based lightguide
wherein the 9-spot sampled spatial color non-uniformity,
.DELTA.u'v', of the of the light reaching the spatial light
modulator (measured by disposing a white reflectance standard
surface such as Spectralon in the location where the spatial light
modulator would be located to receive light from the lightguide and
measuring the color of the standard surface on the 1976 u', v
Uniform Chromaticity Scale as described in VESA Flat Panel Display
Measurements Standard version 2.0, Jun. 1, 2001 (Appendix 201, page
249) is less than one selected from the group: 0.2, 0.1, 0.05,
0.01, and 0.004 when measured using a spectrometer based spot color
meter. In another embodiment, a display comprises a spatial light
modulator and a light emitting device comprising a light source, a
light input coupler, and a film-based lightguide wherein the 9-spot
sampled spatial color non-uniformity, .DELTA.u'v', of the display
measured on the 1976 u', v.degree. Uniform Chromaticity Scale as
described in VESA Fiat Panel Display Measurements Standard version
2.0, Jun. 1, 2001 (Appendix 201, page 249) is less than one
selected from the group: 0.2, 0.1, 0.05, 0.01, and 0.004 when
measured using a spectrometer based spot color meter.
Angular Profile of Light Emitting from the Light Emitting
Device
[0451] In one embodiment, the light emitting from at least one
surface of the light emitting device has an angular full-width at
half-maximum intensity (MEM) less than one selected from the group:
120 degrees, 100 degrees, 80 degrees, 60 degrees, 40 degrees, 20
degrees and 10 degrees. In another embodiment, the light emitting
from at least one surface of the light emitting device has at least
one angular peak of intensity within at least one angular range
selected from the group: 0-10 degrees, 20-30 degrees, 30-40
degrees, 40-50 degrees, 60-70 degrees, 70-80 degrees, 80-90
degrees, 40-60 degrees, 30-60 degrees, and 0-80 degrees from the
normal to the light emitting surface. In another embodiment, the
light emitting from at least one surface of the light emitting
device has two peaks within one or more of the aforementioned
angular ranges and the light output resembles a "bat-wing" type
profile known in the lighting industry to provide uniform
illuminance over a predetermined angular range. In another
embodiment, the light emitting device emits light from two opposing
surfaces within one or more of the aforementioned angular ranges
and the light emitting device is one selected from the group: a
backlight illuminating two displays on either side of the
backlight, a light fixture providing up-lighting and down-lighting,
a frontlight illuminating a display and having light output on the
viewing side of the frontlight that has not reflected from the
modulating components of the reflective spatial light modulator
with a peak angle of luminance greater than 40 degrees, 50 degrees,
or 60 degrees. In another embodiment, the optical axis of the light
emitting device is within an angular range selected from the group:
0-20, 20-40, 40-60, 60-80, 80-100, 100-120, 120-140, 140-160,
160-180, 35-145, 45-135, 55-125, 65-115, 75-105, and 85-95 degrees
from the normal to a light emitting surface. In further embodiment,
the shape of the lightguide is substantially tubular and light
substantially propagates through the tube in a direction parallel
to the longer (length) dimension of the tube and the light exits
the tube wherein at least 70% of the light output flux is contained
within an angular range of 35 degrees to 145 degrees from the light
emitting surface. In a further embodiment, the light emitting
device emits light from a first surface and a second surface
opposite the first surface wherein the light flux exiting the first
and second surfaces, respectively, is chosen from the group of
5-15% and 85-95%, 15-25% and 75-85%, 25-35% and 65-75%, 35-45% and
65-75%, 45-55% and 45-55%. In another embodiment, the first light
emitting surface emits light in a substantially downward direction
and the second light emitting surface emits light substantially in
an upward direction. In another embodiment, the first light
emitting surface emits light in a substantially upward direction
and the second light emitting surface emits light substantially in
a downward direction.
Optical Redundancy
[0452] In one embodiment, the light emitting device comprises
coupling lightguides which provide a system for optical redundancy.
Optical redundancy provides for the ability for the device to
function at acceptable illuminance uniformity, luminance
uniformity, or color uniformity levels through multiple optical
paths from different light sources that overlap in at least one
region. The optical redundancy may be achieved through stacking
lightguides, coupling light from more than one light source into a
light input coupler, or disposing light input couplers for the same
lightguide film on a plurality of sides of the lightguide (such as
on opposite sides of the lightguide). More than one method of
achieving optical redundancy may be employed, for example, by
stacking two or more lightguides that each comprises light input
couplers that are each disposed to receive light from a plurality
of light sources.
[0453] Optical redundancy may be used to increase the spatial or
angular uniformity (luminance, illuminance, or color), provide a
combination of angular or spatial light output profiles (low
angular output from one lightguide and high angular output from a
second lightguide, for example), provide increased luminance
levels, provide a backup light emitting region when component
failure causes light from the first lightguide to fall below
specification (such as color uniformity, luminance uniformity, or
luminance) in the overlapping region, increase the color gamut
(combining light output from white and red LEDs for example), or
provide color mixing (combining the output from red, green, and
blue LEDs for example).
[0454] In one embodiment, optical redundancy is used to maintain or
reduce the unwanted effects of light source failure or component
failure (such as LED driver or a solder joint failure). For
example, two lightguides may each be coupled to a separate light
input coupler with separate light sources and the lightguides may
be stacked in a light output direction and each independently
designed with light extraction features to provide uniform output
in a light emitting region. If the LED fails in the first light
input coupler, the second light input coupler may still operate and
provide uniform light output. Similarly, if the color of the first
LED within the first light input coupler changes due to temperature
or degradation, the effects (color changes such as off-white) will
be less due to the optical redundancy of a stacked system.
[0455] In another embodiment, the light output from two or more
light sources are coupled into the light input coupler of a light
emitting device comprising optical redundancy and the optical
redundancy reduces the color or luminance binning requirements of
the LEDs. In this embodiment, optical redundancy provides for the
mixing of light from a plurality of light sources within a region
(such as within the coupling lightguides) such that the color from
each source is averaged spatially with each coupling lightguide
receiving light from each light source and directing it into the
lightguide or light mixing region.
[0456] In another embodiment, a light emitting device comprises at
least one coupling lightguide disposed to receive light from at
least two light sources wherein the light from the at least two
light sources is mixed within a first region of the at least one
coupling lightguide and the first region is contained within a
distance from the light emitting region of the light emitting
device less than one selected from the group: 100%, 70%, 50%, 40%,
30%, 20%, 10%, and 5% of the largest dimension of the light
emitting device output surface or light emitting region.
[0457] In a further embodiment, a light emitting device comprising
a plurality of light sources comprises optical redundancy and the
device may be dimmed by adjusting the light output of one or more
LEDs while leaving the output driving pattern of one or more LEDs
substantially constant. For example, a light emitting device
comprising a first string of LEDs L1, L2, and L3 connected in an
electrical series and optically coupling light into light input
couplers LIC1, LIC2, and LIC3, respectively, and further comprising
a second string of LEDs L4, L5, and L6 connected in an electrical
series and optically coupling light into light input couplers LIC1,
LIC2, and LIC3, respectively, can be uniformly dimmed (dimmed while
maintaining spatial luminance uniformity of the light emitting
surface, for example) from, for example 50% to 100% output
luminance, by adjusting the current to the second string of LEDs.
Similarly, the color of the light output can be uniformly adjusted
by increasing or decreasing the electrical current to the second
string when the color of the light output of the second string is
different than the color output of the first string. Similarly,
three or more strings may be controlled independently to provide
optical redundancy or uniform adjustment of the luminance or color.
Three or more groups with different colors (red, green, and blue,
for example) may be adjusted independently to vary the output color
while providing spatial color uniformity.
Stacked Lightguides
[0458] In one embodiment, a light emitting device comprises at
least one film lightguide or lightguide region disposed to receive
and transmit light from a second film lightguide or lightguide
region such that the light from the second lightguide improves the
luminance uniformity, improves the illuminance uniformity, improves
the color uniformity, increases the luminance of the light emitting
region, or provides a back-up light emitting region when component
failure causes light from the first lightguide to fall below
specification (such as color uniformity, luminance uniformity, or
luminance) in the overlapping region.
Plurality of Light Sources Coupling into Light Input Coupler
[0459] In another embodiment, a plurality of light sources are
disposed to couple light into a light input coupler such that a
portion of the light from the plurality of light sources is coupled
into at least one coupling lightguide such that the light output is
combined. By combining the light output from a plurality of light
sources within the coupling lightguides, the light is "mixed"
within the coupling lightguides and the output is more uniform in
color, luminance, or both. For example, two white LEDs disposed
adjacent a light input surface of a collection of coupling
lightguides within a light input coupler can have substantially the
same spatial luminance or color uniformity in the light emitting
region if one of the light sources fails. In another embodiment,
light sources emitting light of two different colors are disposed
to couple light into the same light input coupler. The light input
coupler may provide the mixing within the coupling lightguides, and
furthermore, the coupling lightguides provide optical redundancy in
case one light source fails. The optical redundancy can improve the
color uniformity when light sources of two or more colors are
coupled into the same light input coupler. For example, three white
LEDs, each with different color temperatures, may be coupled into
the same light input coupler and if one of the light LEDs fails,
then the light output from the other two LEDs is still mixed and
provides more uniformity than single LEDs with different color
outputs coupled into two adjacent light input couplers. In one
embodiment, a light source comprises at least one selected from the
group: 3, 5, 10, 15, 20, 25 and 30 LED chips disposed in an array
or arrangement to couple light into a single light input coupler.
In one embodiment, a light source comprises at least one selected
from the group: 3, 5, 10, 15, 20, 25 and 30LED chips disposed in an
array or arrangement to couple light into more than one light input
coupler. In a further embodiment a light source disposed to couple
light into a light input coupler comprises a plurality of LED chips
with a light emitting surface area with a light emitting dimension
less than one selected from the group: 0.25 millimeters, 0.3
millimeters, 0.5 millimeters, 0.7 millimeters, 1 millimeter, 1.25
millimeters, 1.5 millimeters, 2 millimeters and 3 millimeters.
Light Input Couplers on Different Sides of the Lightguide
[0460] In another embodiment, a plurality of light input couplers
are disposed on two or more edge regions of a lightguide wherein
the optical axes of the light exiting the coupling lightguides are
oriented at an angle greater than 0 degrees to each other. In a
further embodiment, the light input couplers are disposed on
opposite or adjacent edges or sides of the lightguide. In one
embodiment, a light emitting device comprises a plurality of light
input couplers disposed on two or more edge regions of a lightguide
and the luminance or color uniformity of the light emitting region
is substantially the same when the light output of the first light
input coupler is increased or decreased relative to the light
output of the second light input coupler. In one embodiment, the
light extraction features are disposed within the light emitting
region such that the spatial luminance uniformity is greater than
70% when receiving light from only the first light input coupler
and receiving light from the first and second light input couplers.
In another embodiment, the light extraction features are disposed
within the light emitting region such that the 9-spot spatial color
non-uniformity is less than 0.01 when receiving light from only the
first light input coupler and receiving light from the first and
second light input couplers.
Other Applications of the Light Device
[0461] Since the present invention enables inexpensive coupling
into thin-films, there are many general illumination and
backlighting applications. The first example is general home and
office lighting using roll-out films on walls or ceiling. Beyond
that, the film can bend to shape to non-planar shapes for general
illumination. Additionally, it can be used as the backlight or
frontlight in the many thin displays that have been or are being
developed. For example, LCD and E-ink thin-film displays may be
improved using a thin back-lighting film or thin frontlighting
film; Handheld devices with flexible and scrollable displays are
being developed and they need an efficient, low-cost method for
getting light into the backlighting film. In one embodiment, the
light emitting device comprises a light input coupler, lightguide,
and light source which provide illumination for translucent objects
or film such as stained glass windows or signs or displays such as
point-of-purchase displays. In one embodiment, the thin film
enables the light extraction features to be printed such that they
overall negligibly scatter light that propagates normal to the face
of the film. In this embodiment, when the film is not illuminated,
objects can be seen clearly through the film without significant
haze. When placed behind a transparent or partially transparent
stained glass window, the overall assembly allows low-scattering
transmission of light through the assembly if desired. Furthermore,
the flexibility of the film allows for much greater positional
tolerances and design freedom than traditional plate lightguide
backlights because the film can be bent and adapted to the various
stained glass window shapes, sizes and topologies. In this
embodiment, when not illuminated, the stained glass appears as a
regular non-illuminated stained glass window. When illuminated, the
stained glass window glows.
[0462] Additional embodiments include light emitting devices
wherein the stained glass window is strictly aesthetic and does not
require viewing of objects through it (e.g. cabinet stained glass
windows or art displays), and the overall see-through clarity of
the backlight does not need to be achieved. In this embodiment, a
diffuse or specular reflector can be placed behind the film to
capture light that illuminates out of the film in the direction
away from the stained glass window. Diffusing films, light
redirecting films, reverse prism films, diffuser films (volumetric,
surface relief or a combination thereof) may be disposed between
the lightguide and the object to be illuminated. Other films may be
used such as other optical films known to be suitable to be used
within an LCD backlight.
[0463] In another embodiment, a light emitting device is used as an
overlay with indicia that can be illuminated. In one embodiment,
the lightguide region has a low degree of visibility in the
off-state, and an in the on-state can be clearly seen as
illuminated indicia. For example, the lightguide region may be
printed with light scattering dots to illuminate and display
indicia such as "Warning," "Exit," "Sale," "Enemy Aircraft
Detected," "Open," "Closed," "Merry Christmas," etc. The lightguide
region may be disposed on the viewing side of a display (such as
LCD, Plasma, Projection Screen, etc.) or it may be placed on a
store or home window, on a table surface, a road sign, on a vehicle
or air/water/land craft exterior or window, over or inside a
transparent, translucent, or opaque object, on a door, stairs, in a
hallway, within a doormat, etc. The indicia may also be icons,
logos, images, or other representations such as a cartoon-like
drawing of Santa Claus, a brand logo such as the Nike Swoosh, a
photo of a beach scene, a dithered photo of the face of a person,
etc. The indicia may be full-color, monochrome or comprise mixtures
of colored and monochrome regions and may be layered or employ
phosphors, dyes, inks or pigments to achieve colors.
[0464] By using a lightguide film which is substantially not
visible in the off-state, the display, sign, or light emitting
device can be employed in more places without substantially
interfering with appearance of the object on which it is disposed.
In another embodiment, the light emitting device provides
illumination of a space wherein the region which emits light in the
on-state is not readily discernible in the off-state. This, for
example, can provide thin light fixtures or illumination devices
that are substantially only visible in the on-state. For example,
vehicle tail lights, seasonal window film displays, ceiling mounted
light fixtures, lamps, closed signs, road hazard signs,
danger/warning signs, etc. may be substantially invisible in the
off-state. In some situations, this enables the signs to be posted
and only turned on when needed and can reduce delays incurred due
to the installation time required. In another embodiment, the light
emitting device is a light fixture which appears to be the color of
the background surface upon which it is place upon in the
off-state. In another embodiment, the light emitting area of the
light fixture is substantially black or light absorbing in the
off-state. Such displays are useful in submarines or other aircraft
under NVIS illumination conditions.
[0465] The light emitting device of one embodiment can be used for
backlighting or frontlighting purposes in passive displays, e.g.,
as a backlight or frontlight for an illuminated advertising poster,
as well as for active (changing) displays such as LCD displays.
Suitable displays include, but are not limited to, mobile phone
displays, mobile devices, aircraft display, watercraft displays,
televisions, monitors, laptops, watches (including one where the
band comprises a flexible lightguide which is capable of
illumination or "lighting up" in a predetermined pattern by an LED
within the watch or watch band), signs, advertising displays,
window signs, transparent displays, automobile displays, electronic
device displays, and other devices where LCD displays are known to
be used.
[0466] Some applications generally require compact, low-cost
white-light illumination of consistent brightness and color across
the illuminated area. It is cost-effective and energy-efficient to
mix the light from red, blue, and green LEDs for this purpose, but
color mixing is often problematic. In one embodiment, light from
red, blue, and green light sources is directed into each stack of
coupling lightguides/input areas and is sufficiently mixed that it
appears as white light when it exits the lightguide region of the
lightguide. The light sources can be geometrically situated, and
adjusted in intensity, to better provide uniform intensities and
colors across the lightguide region. A similar arrangement can be
attained by providing stacked sheets (more specifically stacked
sheet bodies or lightguides) wherein the colors in the sheets
combine to provide white light. Since some displays are provided on
flexible substrates for example, "E-ink" thin-film displays on
printed pages--the sheets provide a means for allowing backlighting
while maintaining the flexibility of the display's media.
[0467] In some embodiments, the light emitting device is a novel
LCD backlighting solution, which includes mixing multiple colors of
LEDs into a single lightguide. In one embodiment, the length and
geometry of the strips uniformly mixes light into the lightguide
region of the film lightguide without a significant are of light
mixing region located around the edge. The enhanced uniformity of
the colors can be used for a static display or a color-sequential
LCD and BLU system. One method for a color-sequential system is
based on pulsing between red, green, and blue backlight color while
synced to the LCD screen pulsing. Moreover, a layered version of
red-, green- and blue-lighted films that combine to make white
light is presented. A pixel-based display region can have multiple
pixels that are designated to be red, green or blue. Behind it are
three separate film lightguides that each have a separate color of
light coupled to them. Each of the lightguides has light extraction
features that match up with the corresponding color of the
pixel-based display. For example red light is coupled into coupling
lightguide and then into the lightguide or lightguide region and is
extracted from the feature into the red pixel. The film lightguides
are considerably thinner than the width of the pixels so that
geometrically a high percentage of the light from a given color
goes into its corresponding set of pixels. Ideally, no color filter
needs to be used within the pixels, but in case there is cross-talk
between pixels, they should be used.
[0468] It is also notable that the invention has utility when
operated "in reverse"--that is, the light-emitting face(s) of a
sheet could be used as a light collector, with the sheet collecting
light and transmitting it through the coupling lightguides to a
photosensitive element. As an example, sheets in accordance with
the invention could collect incoming light and internally reflect
it to direct it to a photovoltaic device for solar energy
collection purposes. Such an arrangement can also be useful for
environmental monitoring sensing purposes, in that the sheet can
detect and collect light across a broad area, and the detector(s)
at the coupling lightguides will then provide a measurement
representative of the entire area. A sheet could perform light
collection of this nature in addition to light emission. For
example, in lighting applications, a sheet might monitor ambient
light, and then might be activated to emit light once twilight or
darkness is detected. Usefully, since it is 15 known that LEDs can
also be "run in reverse"--that is, they can provide output
current/voltage when exposed to light if LEDs are used as an
illumination source when a sheet is used for light emission, they
can also be used as detectors when a sheet is used for light
collection. In one embodiment, the lightguide captures a portion of
incident light and directs it to a detector wherein the detector is
designed to detect a specific wavelength (such as by including a
bandpass filter, narrowband filter or a diode with a specific
bandgap used in reverse). These light detection devices have the
advantages of collecting a percentage of light over a large area
and detecting light of a specific wavelength is directed toward the
film while the film/sheet/lightguide/device remains substantially
transparent. These can be useful in military operations where one
is interested in detecting lasers or light sources (such as used in
sighting devices, aiming devices, laser-based weapons, LIDAR or
laser based ranging devices, target designation, target ranging,
laser countermeasure detection, directed energy weapon detection,
eye-targeted or dazzler laser detection) or infra-red illuminators
(that might be used with night vision goggles).
[0469] In another embodiment, a light emitting device comprises a
light source, light input coupler, and film-based lightguide
wherein the light emitting device is one selected from the group:
can light, troffer light, cove light, torch tamp, floor lamp,
chandelier, surface mounted light, pendant light, sconce, track
light, under-cabinet light, emergency light, wall-socket light,
exit light, high bay light, low bay light, strip light, garden
light, landscape light, building light, outdoor light, street
light, pathway light, bollard light, yard light, accent light,
background light, black light, flood light, safelight, safety tamp,
searchlight, security light, step light, strobe light, follow-spot
light, or wall-washer light.
[0470] In another embodiment, a light emitting device comprises a
light source, light input coupler, and film-based lightguide
wherein the light emitting device is one selected from the group:
building mounted sign, freestanding sign, interior sign, wall sign,
fascia sign, awning sign, projecting sign, sign band, roof sign,
parapet sign, window sign, canopy sign, pylon sign, joint tenant
sign, monument sign, pole sign, high-rise pole sign, directional
sign, electronic message center sign, video sign, electronic sign,
billboard, electronic billboard, interior directional sign,
interior directory sign, interior regulatory sign, interior mall
sign, and interior point-of-purchase sign.
[0471] The sheets are also highly useful for use in illuminated
signs, graphics, and other displays. For example, the film may be
placed on walls or windows without significantly changing the wall
or window appearance. However, when the sign is illuminated, the
image etched into the film lightguide would become visible. The
present invention could also be useful for coupling light into the
films that sit in front of some grocery store freezers as
insulation, Lighting applications where there is limited space,
such as in the ice at hockey rinks may also require plastic film
lighting. Since a sheet can be installed on a wall or window
without significantly changing its appearance, with the
light-emitting area(s) becoming visible when the light source(s)
are activated, the invention allows displays to be located at areas
where typical displays would be aesthetically unacceptable (e.g.,
on windows). The sheets may also be used in situations where space
considerations are paramount, e.g., when lighting is desired within
the ice of skating rinks (as discussed in U.S. Pat. No. 7,237,396,
which also describes other features and applications that could be
utilized with the invention). The flexibility of the sheets allows
them to be used in lieu of the curtains sometimes used for 15
climate containment, e.g., in the film curtains that are sometimes
used at the fronts of grocery store freezers to better maintain
their internal temperatures. The flexibility of the sheets also
allows their use in displays that move, e.g., in light emitting
flags that may move in the breeze.
Method of Manufacturing Light Input/output Coupler
[0472] In one embodiment, the lightguide and light input or output
coupler are formed from a light transmitting film by creating
segments of the film corresponding to the coupling lightguides and
translating and bending the segments such that a plurality of
segments overlap. In a further embodiment, the input surfaces of
the coupling lightguides are arranged to create a collective light
input surface by translation of the coupling lightguides to create
at least one bend or fold.
[0473] In another embodiment, a method of manufacturing a
lightguide and light input coupler comprising a light transmitting
film with a lightguide region continuously coupled to each coupling
lightguide in an array of coupling lightguides, said array of
coupling lightguides comprising a first linear fold region and a
second linear fold region, comprises the steps of: (a) increasing
the distance between the first linear fold region and the second
linear fold region of the array of coupling lightguides in a
direction perpendicular to the light transmitting film surface at
the first linear fold region; (b) decreasing the distance between
the first linear fold region and the second linear fold region of
the array of coupling lightguides in a direction substantially
perpendicular to the first linear fold region and parallel to the
light transmitting film surface at the first linear fold region;
(c) increasing the distance between the first linear fold region
and the second linear fold region of the array of coupling
lightguides in a direction substantially parallel to the first
linear fold region and parallel to the light transmitting film
surface at the first linear fold region; decreasing the distance
between the first linear fold region and the second linear fold
region of the array of coupling lightguides in a direction
perpendicular to the light transmitting film surface at the first
linear fold region; (d) such that the coupling lightguides are
bent, disposed substantially one above another, and aligned
substantially parallel to each other. These steps (a), (b), (c) and
(d) do not need to occur in alphabetical order and the linear fold
regions may be substantially parallel.
[0474] In one embodiment, the method of assembly includes
translating the first and second linear fold regions of the array
of coupling lightguides (segments) in relative directions such that
the coupling lightguides are arranged in an ordered, sequential
arrangement and a plurality of coupling lightguides comprise a
curved bend. The coupling lightguides can overlap and can be
aligned relative to one another to create a collection of coupling
lightguides. The first linear fold region of the collection of
coupling may be further bent, curved, or folded, glued, clamped,
cut, or otherwise modified to create a light input surface wherein
the surface area is suitable to receive and transmit light from a
light source into the coupling lightguides. Linear fold regions are
regions of the light transmitting film that comprise a fold after
the coupling lightguides are bent in at least one direction. The
linear fold regions have a width that at least comprises at least
one bend of a coupling lightguide and may further include the
region of the film physically, optically, or mechanically coupled
to a relative position maintaining element. The linear fold regions
are substantially co-planar with the surface of the film within the
region and the linear fold regions have a length direction
substantially larger than the width direction such that the linear
fold regions have a direction of orientation in the length
direction parallel to the plane of the film. In one embodiment, the
array of coupling lightguides are oriented at an angle greater than
0 degrees and less than 90 degrees to the first linear fold
region.
[0475] As used herein, the first linear fold region or the second
linear fold region may be disposed near or include the input or
output end of the coupling lightguides. In embodiments where the
device is used to collect light, the input end may be near the
light mixing region, lightguide region, or lightguide and the
output end may be near the light emitting edges of the coupling
lightguides such as in the case where the coupling lightguides
couple light received from the lightguide or lightguide region into
a light emitting surface which is disposed to direct light onto a
photovoltaic cell. In the embodiments and configurations disclosed
herein, the first linear fold region or second linear fold region
may be transposed to create further embodiments for configurations
where the direction of light propagation is substantially
reversed.
[0476] In one embodiment, the array of coupling lightguides have a
first linear folding region and a second linear folding region and
the method of manufacturing the light input coupler comprises
translating steps that create the overlap and bends while
substantially maintaining the relative position of the coupling
lightguides within the first and second linear folding regions. In
one embodiment, maintaining the relative position of the coupling
lightguides assists with the ordered bending and alignment and can
allow the coupling lightguide folding and overlap without creating
a disordered or tangled arrangement of coupling lightguides. This
can significantly improve the assembly and alignment and reduce the
volume required, particularly for very thin films or coupling
lightguides and/or very narrow coupling light strip widths.
[0477] In one embodiment, the aforementioned steps for a method of
manufacturing a lightguide and light input coupler comprising a
light transmitting film with a lightguide region are performed such
that at least at least one of steps (a) and (b) occur substantially
simultaneously; steps (c) and (d) occur substantially
simultaneously; and steps (c) and (d) occur following steps (a) and
(b). In another embodiment, the aforementioned steps for a method
of manufacturing a lightguide and light input coupler comprising a
light transmitting film with a lightguide region are performed such
that steps (a), (b), and (c) occur substantially simultaneously.
The relative translation first linear folding region and the second
linear folding region of the coupling lightguides may be achieved
by holding a linear folding region stationary and translating the
other linear folding region. In a further embodiment, a relative
position maintaining elements disposed at the first folding region
remains substantially stationary while a second relative position
maintaining element at the second linear folding region is
translated. The translation may occur in an arc-like pattern within
one or more planes, or in directions parallel to or at an angle to
the x, y, or z axis.
[0478] In another embodiment, the aforementioned steps are
performed while substantially maintaining the relative position of
the of the array of coupling lightguides within the first linear
fold region relative to each other in a direction parallel to the
first linear fold region and substantially maintaining the relative
position of the array of coupling lightguides within the second
linear fold region relative to each other in a direction parallel
to the first linear fold region.
[0479] In a further embodiment, the distance between the first
linear fold region and second linear fold region of the array of
coupling lightguides is increased by at least the distance, D, that
is the total width, W.sub.t, of the array of the coupling
lightguides in a direction substantially parallel to the first
linear fold region.
[0480] In another embodiment, the array of coupling lightguides
comprises a number, N, of coupling lightguides that have
substantially the same width, W.sub.s, in a direction parallel to
the first linear fold region and D=N.times.W.sub.s.
Relative Position Maintaining Element
[0481] In one embodiment, at least one relative position
maintaining element substantially maintains the relative position
of the coupling lightguides in the region of the first linear fold
region, the second linear fold region or both the first and second
linear fold regions. In one embodiment, the relative position
maintaining element is disposed adjacent the first linear fold
region of the array of coupling lightguides such that the
combination of the relative position maintaining element with the
coupling lightguide provides sufficient stability or rigidity to
substantially maintain the relative position of the coupling
lightguides within the first linear fold region during
translational movements of the first linear fold region relative to
the second linear fold region to create the overlapping collection
of coupling lightguides and the bends in the coupling lightguides.
The relative position maintaining element may be adhered, clamped,
disposed in contact, disposed against a linear fold region or
disposed between a linear fold region and a lightguide region. The
relative position maintaining element may be a polymer or metal
component that is adhered or held against the surface of the
coupling lightguides, light mixing region, lightguide region or
film at least during one of the translational steps. In one
embodiment, the relative position maintaining element is a
polymeric strip with planar or saw-tooth-like teeth adhered to
either side of the film near the first linear fold region, second
linear fold region, or both first and second linear fold regions of
the coupling lightguides. By using saw-tooth-like teeth, the teeth
can promote or facilitate the bends by providing angled guides. In
another embodiment, the relative position maintaining element is a
mechanical device with a first clamp and a second clamp that holds
the coupling lightguides in relative position in a direction
parallel to the clamps parallel to the first linear fold region and
translates the position of the clamps relative to each other such
that the first linear fold region and the second linear fold region
are translated with respect to each other to create overlapping
coupling lightguides and bends in the coupling lightguides. In
another embodiment, the relative position maintaining element
maintains the relative position of the coupling lightguides in the
first linear fold region, second linear fold region, or both the
first and second linear fold regions and provides a mechanism to
exert force upon the end of the coupling lightguides to translate
them in at least one direction.
[0482] In another embodiment, the relative position maintaining
element comprises angular teeth or regions that redistribute the
force at the time of bending at least one coupling lightguide or
maintains an even redistribution of force after at least one
coupling lightguide is bent or folded. In another embodiment, the
relative position maintaining element redistributes the force from
bending and pulling one or more coupling lightguides from a corner
point to substantially the length of an angled guide. In another
embodiment, the edge of the angled guide is rounded.
[0483] In another embodiment, the relative position maintaining
element redistributes the force from bending during the bending
operation and provides the resistance to maintain the force
required to maintain a low profile (short dimension in the
thickness direction) of the coupling lightguides.
[0484] In a further embodiment, the relative position maintaining
element is also a thermal transfer element. In one embodiment, the
relative position maintaining element is an aluminum component with
angled guides or teeth that is thermally coupled to an LED light
source.
[0485] In a further embodiment, the input ends and output ends of
the array of coupling lightguides are each disposed in physical
contact with relative position maintaining elements during the
aforementioned steps (a), (b), (c) and (d).
[0486] In one embodiment, a relative position maintaining element
disposed proximal to the first linear fold region of the array of
coupling lightguides has an input cross-sectional edge in a plane
parallel to the light transmitting film that is substantially
linear and parallel to the first linear fold region, and a relative
position maintaining element disposed proximal to the second linear
fold region of the array of coupling lightguides at the second
linear fold region of the array of coupling lightguides has a
cross-sectional edge in a plane parallel to the light transmitting
film at the second linear fold region substantially linear and
parallel to the linear fold region.
[0487] In another embodiment, the cross-sectional edge of the
relative position maintaining element disposed proximal to the
first linear fold region of the array of coupling lightguides
remains substantially parallel to the cross-sectional edge of the
relative position maintaining element disposed proximal to the
second linear fold region of the array of coupling lightguides
during steps (a), (b), (c), and (d).
[0488] In a further embodiment, the relative position maintaining
element disposed proximal to the first linear fold region has a
cross-sectional edge in a plane parallel to the light transmitting
film surface disposed proximal to the first linear fold region that
comprises a substantially linear section oriented at an angle
greater than 10 degrees to the first linear fold region for at
least one coupling lightguide. In a further embodiment, the
relative position maintaining element has saw-tooth-like teeth
oriented substantially at 45 degrees to a linear fold region of the
coupling lightguides.
[0489] In one embodiment, the cross-sectional edge of the relative
position maintaining element forms a guiding edge to guide the bend
of at least one coupling lightguide.
[0490] In another embodiment, the aforementioned method further
comprises the step of cutting through the overlapping coupling
lightguides to provide an array of input edges of the coupling
lightguides that end in substantially one plane orthogonal to the
light transmitting film surface. The coupling lightguides may be
formed by cutting the film in lines to form slits in the film. In
another embodiment, the aforementioned method of manufacture
further comprises forming an array of coupling lightguides in a
light transmitting film by cutting substantially parallel lines
within a light transmitting film. In one embodiment, the slits are
substantially parallel and equally spaced apart. In another
embodiment, the slits are not substantially parallel or have
non-constant separations.
[0491] In another embodiment, the aforementioned method further
comprises the step of holding the overlapping array of coupling
lightguides in a fixed relative position by at least one selected
from the group: clamping them together, restricting movement by
disposing walls or a housing around one or more surfaces of the
overlapping array of coupling lightguides, and adhering them
together or to one or more surfaces.
[0492] In another embodiment, a method of manufacturing a
lightguide and light input coupler comprising a light transmitting
film with a lightguide region continuously coupled to each coupling
lightguide in an array of coupling lightguides, said array of
coupling lightguides comprising a first linear fold region and a
second linear fold region substantially parallel to the first fold
region, comprises the steps: (a) forming an array of coupling
lightguides physically coupled to a lightguide region in a light
transmitting film by physically separating at least two regions of
a light transmitting film in a first direction; (b) increasing the
distance between the first linear fold region and the second linear
fold region of the array of coupling lightguides in a direction
perpendicular to the light transmitting film surface at the first
linear fold region; (c) decreasing the distance between the first
linear fold region and the second linear fold region of the array
of coupling lightguides in a direction substantially perpendicular
to the first linear fold region and parallel to the light
transmitting film surface at the first linear fold region; (d)
increasing the distance between the first linear fold region and
the second linear fold region of the array of coupling lightguides
in a direction substantially parallel to the first linear fold
region and parallel to the light transmitting film surface at the
first linear fold region; and (e) decreasing the distance between
the first linear fold region and the second linear fold region of
the array of coupling lightguides in a direction perpendicular to
the light transmitting film surface at the first linear fold
region; such that the coupling lightguides are bent, disposed
substantially one above another, and aligned substantially parallel
to each other.
[0493] In another embodiment, a method of manufacturing a
lightguide and light input coupler comprising a light transmitting
film with a lightguide region optically and physically coupled to
each coupling lightguide in an array of coupling lightguides, said
array of coupling lightguides comprising a first fold region and a
second fold region, comprises the steps of (a) translating the
first fold region and the second fold region away from each other
in a direction substantially perpendicular to the film surface at
the first fold region such that they move toward each other in a
plane parallel to the film surface at the first fold region and (b)
translating the first fold region and the second fold region away
from each other in a direction parallel to the first fold region
such that the first fold region and second fold region move toward
each other in a direction substantially perpendicular to the film
surface at the first fold region such that the coupling lightguides
are bent and disposed substantially one above another.
Stress Induced Scattering
[0494] The bending or folding of a film-based coupling lightguide
may result in stress-induced scattering in a region that caused a
portion of the light within the coupling lightguide to be scattered
into a direction such that it exits the lightguide near the region.
The stress induced scattering may be of the type stress cracking,
stress whitening, shear bands, stress crazing, or other visible
material deformation resulting in a scattering region due to
stress.
[0495] Stress induced deformations such as stress cracking, stress
whitening, shear bands, and stress crazing are described in
"Characterization and failure analysis of plastics," ASM
International (2003).
[0496] Stress cracking, as used herein, is the localized failure
that occurs when localized stresses produce excessive localized
strain. This localized failure results in the formation of
microcracks that spread rapidly throughout the local area. Brittle
materials are more prone to stress cracking that stress whitening.
Stress whitening is a generic term describing many different
microscopic phenomena that produce a cloudy, foggy, or whitened
appearance in transparent or translucent polymers in stress. The
cloudy appearance is the result of a localized change in polymer
refractive index or creation of an air void. Thus, transmitted
light is scattered. Microvoid clusters of dimension near or greater
than the wavelength of light are thought to be the primary cause of
stress whitening. The microvoids can be caused by the delamination
of tillers or fibers, or they can be localized failure around
occlusions, such as rubber particles or other impact modifiers.
Shear bands are also microscopic localized deformation zones that
propagate ideally along shear planes. Like crazes,
shear-deformation bands, or slip lines are traditionally thought to
be the mechanism of irreversible tensile deformation in ductile
amorphous polymers. Almost invariably, a compressive-stress state
will cause shear deformation in polymers. Under monotonic tensile
loading, polycarbonate is reported to deform by shear banding.
Stress crazing is a microcrack that is spanned by plastic
microfibrils, typically oriented in the direction of applied
stress. The width of a craze is of the order of 1 to 2 microns, and
it may grow to several millimeters in length, depending on its
interaction with other heterogeneities. Being dilational, crazes
grow normal to the applied tensile component of the stress
field.
[0497] In one embodiment, stress induced scattering in one or more
coupling lightguides induced by bending or folding is be reduced by
bending or folding the coupling lightguides at a higher
temperature. In another embodiment, stress induced scattering in
one or more coupling lightguides induced by bending or folding is
be reduced after bending or folding by subjecting one more coupling
lightguides or regions of coupling lightguides to a temperature
higher than one selected from the group: the glass transition
temperature, the ASTM D1525 Vicat softening temperature, the
temperature 10 degrees less than the glass transition temperature,
and the temperature equal to or higher than the melt
temperature.
Coupling Lightguides Heated while Bending
[0498] In one embodiment, the coupling lightguides are bent or
folded while heated to temperature above 30 degrees Celsius. In one
embodiment, coupling lightguides comprising at least one material
which results in stress induced scattering when bent or folded at a
first temperature less than 30 degrees Celsius are heated to a
temperature greater than 30 degrees Celsius and bent or folded to
create bend or fold regions that are substantially free of stress
induced scattering. A coupling lightguide substantially free of
stress induced scattering does not scatter more than 1% of the
light propagating within the coupling lightguide out of the
lightguide in the bend, fold or stressed region due stress induced
scattering of light out of the coupling lightguide when illuminated
with light from a light input coupler. A coupling lightguide
substantially free of stress induced scattering does not have a
scattering regions visible by eye in the area of the bend, fold, or
stressed region when the coupling lightguide is viewed in
transmission by eye at 5 degrees off-axis to the light incident to
the coupling lightguide normal to the surface from a halogen light
source collimated to less than 20 degrees at a distance of 3.048
meters.
[0499] In one embodiment, the bending or folding of the coupling
lightguides occurs at a temperature of at least one selected from
the group: greater than room temperature, greater than 27 degrees
Celsius, greater than 30 degrees Celsius, greater than 40 degrees
Celsius, greater than 50 degrees Celsius, greater than 60 degrees
Celsius, greater than the glass transition temperature of the core
material, greater than the glass transition temperature of the
cladding material, greater than the ASTM D 1525 Vicat softening
temperature of the core material, greater than the ASTM D1525 Vicat
softening temperature of the cladding material, and greater than
the ASTM D1525 Vicat softening temperature of the coupling
lightguide film or film composite.
Coupling Lightguide with Fold Regions
[0500] In one embodiment, a lightguide comprises a coupling
lightguide comprising fold regions defined by fold lines and a
reflective edge that substantially overlap such that the collection
of light input edges form a light input surface. In a further
embodiment, one or more fold regions comprise a first reflective
surface edge disposed to redirect a portion of light from a light
source input at a light input edge of the film into an angle less
than the critical such that it does not escape the coupling
lightguide at the reflective edge or the lightguide region at an
outer edge (such as the edge distal from the light source). In
another embodiment, one or more fold regions comprise a second
reflective surface edge disposed to redirect a portion of light
input from a light input edge of the film into an angle such that
it does not escape the coupling lightguide at the reflective edge.
In a further embodiment, the first and second reflected surface
edges substantially collimate a portion of the light from the light
source. In another embodiment, the first and second reflected
surface edges have a parabolic shape.
[0501] The reflective surface edge may be an edge of the film
formed through a cutting, stamping or other edge forming technique
and the reflective properties may be due to total internal
reflection or an applied coating (such as a reflective ink coating
or sputter coated aluminum coating). The reflective surface edge
may be linear, parabolic, angled, arcuate, faceted or other shape
designed to control the angular reflection of light receive from
the light input edge. The first and second reflective surface edges
may have different shapes or orientations to achieve desired
optical functions. The reflective surface edge may serve to
redirect light to angles less than the critical angle, collimate
light, or redirect light flux to a specific region to improve
spatial or angular luminance, color, or light output
uniformity.
[0502] In one embodiment, the reflective edge is angled, curved, or
faceted to direct by total internal reflection a first portion of
the light from the light source into the lightguide region. In a
further embodiment, the reflective edge comprises a reflective
coating.
[0503] In one embodiment, the fold line is angled or curved such
that the fold regions are at least one selected from the group: at
an angle to each other, at an angle to one or more edges of the
light input coupler, lightguide region, or light input surface, and
at an angle to the optical axis of a light source, wherein the
angle is greater than 0 degrees and less than 180 degrees.
[0504] One or more regions or edges of the film-based lightguide,
such as the reflective edges or the reflective surface edges may be
stacked and coated. For example, more than one lightguide may be
stacked to coat the reflective edges using sputter coating, vapor
deposition, or other techniques. Similarly, the reflective surface
edges may be folded and coated with a reflective material. Spacers,
protective films or layers or materials may be used to separate the
films or edges.
[0505] A lightguide with fold regions can reduce or eliminate the
need for cutting and folding the coupling lightguides. By forming
reflective surface edges such as collimating surfaces for light
incident from the light source which are cut from the single film,
light can be redirected such that light does not escape out of the
lightguide at the angled edge (from the light sources nearest the
lightguide region, for example) and the light from the light source
is not coupled out of the lightguide at the opposite edge (such as
light from the LEDs nearest the lightguide incident on the opposite
edge of the lightguide region at an angle less than the critical
angle). In a further embodiment, the shape of the first and second
reflective surface edges varies from the light source nearest the
lightguide region or light emitting region toward the farthest fold
region from the lightguide region or light emitting region. In one
embodiment, the light source farthest from the lightguide region or
light emitting region has a second reflective surface edge formed
by the reflective edge and the first reflective surface edge is
angled to permit light from the light source to reach the
lightguide region or light emitting region without reflecting from
the reflective edge. In a further embodiment, the second reflective
surface edges redirect light from the light source incident in a
direction away from the lightguide region or light emitting region
(in the unfolded layout) toward the reflective edge at an angle
greater than the critical angle and the first reflective surface
edges redirect light from the tight source incident in a direction
toward the lightguide region or light emitting region toward the
reflective edge at an angle greater than the critical angle or
allow light from the light source to directly propagate toward the
lightguide region or light emitting region without reflecting from
the reflective edge.
[0506] In one embodiment, the film-based lightguide with a light
input coupler comprising a coupling lightguide with fold regions is
formed by folding a lightguide film along fold lines and
overlapping the fold regions at a first light input edge. In one
embodiment, the film-based lightguide is folded prior to cutting.
By folding prior to cutting, the edges of the internal layers may
have improved surface qualities when mechanically cutting, for
example. In a further embodiment, the film-based lightguide is cut
prior to folding. By cutting prior to folding, multiple lightguide
films may be stacked together to reduce the number of cuts needed.
Additionally, by cutting prior to folding, the first and second
reflective surfaces may have different individual shapes and the
reflective edge may be angled or curved.
[0507] In a further embodiment, multiple film lightguides are
stacked or disposed one above another in the light input coupler
region and the fold regions (or plurality of coupling lightguides)
are interwoven or alternating. For example, two film-based
lightguides may be stack upon each other and the fold regions may
be simultaneously folded in both lightguides by a mechanical film
folder (such as folding machines used in the paper industry). This
can reduce the number of folding steps, and allow for multiple
lightguides to be illuminated by a single light input coupler or
light source. Interleaving the lightguides can also increase the
uniformity since the light extraction features (location, size,
depth, etc.) within each lightguide may be different and
independently controlled. Additionally, multiple lightguides
wherein the lightguide region or light emitting regions do not
overlap or only partially overlap may be illuminated by a single
light input coupler. For example, by folding two lightguides
together, the display and backlit keypad in a phone, the display
and backlit keyboard in a computer, or the frontlight and keypad in
a portable device such as an electronic book may be illuminated by
the same light source or light source package.
[0508] In a further embodiment, two separate light emitting regions
within a single lightguide film are illuminated by a folded light
input coupler (or light input coupler comprising a plurality of
coupling lightguides).
[0509] The fold regions may be folded to a similar radius of
curvature to the coupling lightguide or strips used in a light
input coupler comprising a plurality of coupling lightguides. In
another embodiment, the lightguide is held in two or more regions
and a plurality of wires are brought toward each other wherein the
wires contact the film near the fold lines in an alternating format
and form the bends in the film. The input edges of the fold regions
or regions of the fold regions may then be held or bonded together
such that the wires can be removed and the folds remain. In one
embodiment, the folds along the fold lines are not "creases" in
that they do not form visible lines or creases when the film is
unfolded. In another embodiment, teeth or plates moving in
directions toward each other press alternating fold lines in
opposite directions and create the "zigzag", accordion-like, or
bellow-like folds in the film. A housing or fold maintaining
element such as a holding device for holding a plurality of
coupling lightguides may be used to hold together, house, or
protect the coupling lightguide formed from a plurality of fold
regions. Similarly to the housing or holding device for a plurality
of coupling lightguides, the housing may comprise an optically
coupled window, refractive lenses or other features, elements or
properties used in the housing, folder, or holding device for a
plurality of coupling lightguides. In a further embodiment, the
housing, folder, or holding device comprises alternating rigid
elements on two opposing parts such that when the elements are
brought together, a film disposed between the elements is folded in
a bellow-like manner creating fold regions within a coupling
lightguide.
Packaging
[0510] In one embodiment, a kit suitable for providing illumination
comprises a light source, a light input coupler, and a
lightguide.
Roll-Up or Retractable Lightguide
[0511] In one embodiment, the flexible light emitting device can be
rolled up into a tube of a diameter less than one selected from the
group: 152.4 mm, 76.2 mm, 50.8 mm, and 25.4 mm. In another
embodiment, the flexible light emitting device comprises a spring
or elastic-based take-up mechanism which can draw a portion of the
lightguide, the light emitting region, or the lightguide region
inside the housing. For example, the light emitting region of the
film can be retracted into a cylindrical tube when a button on the
device is pressed to provide secure, protected storage.
Lamination or Use with Other Films
[0512] In one embodiment, at least one selected from the group:
lightguide, light transmitting film, light emitting device housing,
thermal transfer element, and component of the light emitting
device is laminated to or disposed adjacent to at least one
selected from the group: reflection film, prismatic film reflective
polarizer, low refractive index film, pressure sensitive adhesive,
air gaps, light absorbing films, anti-glare coatings,
anti-reflection coatings, protective film, barrier film and low
tack adhesive film.
Film Production
[0513] In one embodiment, the film or lightguide is one selected
from the group: extruded film, co-extruded film, cast film, solvent
cast film, UV cast film, pressed film, injection molded film, knife
coated film, spin coated film and coated film. In one embodiment,
one or two cladding layers are co-extruded on one or both sides of
a lightguide region. In another embodiment, tie layers, adhesion
promotion layers, materials or surface modifications are disposed
on a surface of or between the cladding layer and the lightguide
layer.
[0514] In another embodiment, at least one selected from the group:
lightguide layer, light transmitting film, cladding region,
adhesive region, adhesion promotion region, or scratch resistant
layer is coated onto one or more surfaces of the film or
lightguide.
[0515] In another embodiment, the lightguide or cladding region is
coated onto, extruded onto or otherwise disposed onto a carrier
film. In one embodiment, the carrier film permits at least one of
easily handling, fewer static problems, the ability to use
traditional paper or packaging folding equipment, surface
protection (scratches, dust, creases, etc.), assisting in obtaining
flat edges of the lightguide during the cutting operation, U'V
absorption, transportation protection, and the use of winding and
film equipment with a wider range of tension and flatness or
alignment adjustments. In one embodiment, the carrier film is
removed before coating the film, before bending the coupling
lightguide, after folding the coupling lightguides, before adding
light extraction features, after adding light extraction features,
before printing, after printing, before or after converting
processes (further lamination, bonding, die cutting, hole punching,
packaging, etc.), just before installation, after installation
(when the carrier film is the outer surface), and during the
removal process of the lightguide from installation.
[0516] In another embodiment, the carrier film is slit or removed
across a region of the coupling lightguides. In this embodiment,
the coupling lightguides can be bent or folded to a smaller radius
of curvature after the carrier film is removed from the linear fold
region.
Separate Coupling Lightguides
[0517] In another embodiment, the coupling lightguides are
discontinuous with the lightguide and are subsequently optically
coupled to the lightguide. In one embodiment, the coupling
lightguides are one selected from the group: extruded onto the
lightguide, optically coupled to the lightguide using an adhesive,
optically coupled to the lightguide by injection molding a light
transmitting material that bonds or remains in contact with the
coupling lightguides and lightguide, thermally bonded to the
lightguide, solvent bonded to the lightguide, laser welded to the
lightguide, sonic welded to the lightguide, chemically bonded to
the lightguide, and otherwise bonded, and adhered or disposed in
optical contact with the lightguide. In one embodiment, the
thickness of the coupling lightguides is one selected from the
group: less than 80%, less than 70%, less than 50%, less than 40%,
less than 20%, less than 10% of the thickness of the
lightguide.
Glass Laminate
[0518] In another embodiment, the lightguide is disposed within or
on one side of a glass laminate. In another embodiment, the
lightguide is disposed within a safety glass laminate. In a further
embodiment, at least one selected from the group: lightguide,
cladding, and adhesive layer comprises polyvinyl butyrate.
Patterned Lightguides
[0519] In another embodiment, at least one selected from the group:
lightguide or coupling lightguides is a coated region disposed on a
cladding, carrier film, substrate or other material. By using a
coated pattern for the lightguide, different pathways for the light
can be achieved for light directed into the coupling lightguides or
lightguide. In one embodiment, the lightguide region comprises
lightguide regions which direct light to separate light emitting
regions wherein the neighboring lightguide regions with light
extracting features emit light of a different color. In another
embodiment, a lightguide pattern is disposed on a cladding layer,
carrier film, or other layer which comprises regions disposed to
emit light of two or more colors from two or more light sources
coupled into input couplers with coupling lightguides disposed to
direct light from the light source to the corresponding patterned
(or trace) lightguide. For example, a red LED may be disposed to
couple light into a light input coupler with coupling lightguides
(which may be film-based or coating based or the same material used
for the pattern lightguide coating) to a lightguide pattern wherein
the light extraction features emit light in a pattern to provide
color in a pixilated color display. In one embodiment, the
lightguide pattern or the light extracting region patterns within
the lightguide pattern comprises one or more selected from the
group: curved sections, bend straight sections, shapes, and other
regular and irregular patterns. The coupling lightguides may be
comprised of the same material as the patterned lightguides or they
may be a different material.
Light Extraction Features
[0520] In one embodiment, the light extraction features are
disposed on or within a film, lightguide region or cladding region
by embossing or employing a "knurl roll" to imprint surface
features on a surface. In another embodiment, the light extraction
features are created by radiation (such as UV exposure) curing a
polymer while it is in contact with a drum, roll, mold or other
surface with surface features disposed thereon. In another
embodiment, light extraction features are formed in regions where
the cladding or low refractive index material or other material on
or within the lightguide is removed or formed as a gap. In another
embodiment, the lightguide region comprises a light reflecting
region wherein light extraction features are formed where the light
reflecting region is removed. Light extraction may comprise or be
modified (such as the percent of light reaching the region that is
extracted or direction profile of the extracted light) by adding
scattering, diffusion, or other surface or volumetric prismatic,
refracting, diffracting, reflecting, or scattering elements within
or adjacent the light extraction features or regions where the
cladding or other layer has been removed.
[0521] In one embodiment, the light extraction features are
volumetric light redirecting features that refract, diffract,
scatter, reflect, totally internally reflect, diffuse, or otherwise
redirect light. The volumetric features may be disposed within the
lightguide, lightguide region, core, cladding, or other layer or
region during the production of the layer or region or the features
may be disposed on a surface whereupon another surface or layer is
subsequently disposed.
[0522] In one embodiment, the light extraction features comprise an
ink or material within a binder comprising least one selected from
the group: titanium dioxide, barium sulfate, metal oxides,
microspheres or other non-spherical particles comprising polymers
(such as PMMA, polystyrene), rubber, or other inorganic materials.
In one embodiment, the ink or material is deposited by one selected
from the group: thermal inkjet printing, piezoelectric inkjet
printing, continuous inkjet printing, screen printing (solvent or
UV), laser printing, sublimation printing, dye-sublimation
printing, UV printing, toner-based printing, LED toner printing,
solid ink printing, thermal transfer printing, impact printing,
offset printing, rotogravure printing, photogravure printing,
offset printing, flexographic printing, hot wax dye transfer
printing, pad printing, relief printing, letterpress printing,
xerography, solid ink printing, foil imaging, foil stamping, hot
metal typesetting, in-mold decoration, and in-mold labeling.
[0523] In another embodiment, the light extraction features are
formed by removing or altering the surface by one selected from the
group: mechanical scribing, laser scribing, laser ablation, surface
scratching, stamping, hot stamping, sandblasting, radiation
exposure, ion bombardment, solvent exposure, material deposition,
etching, solvent etching, plasma etching, and chemical etching.
[0524] In a further embodiment, the light extraction features are
formed by adding material to a surface or region by one selected
from the group: UV casting, solvent casting with a mold, injection
molding, thermoforming, vacuum forming, vacuum thermoforming, and
laminating or otherwise bonding or coupling a film or region
comprising surface relief, and volumetric features.
[0525] In one embodiment, at least one selected from the group:
mask, tool, screen, patterned film or component, photo resist,
capillary film, stencil, and other patterned material or element is
used to facilitate the transfer of the light extraction feature to
the lightguide, film, lightguide region, cladding region or a layer
or region disposed on or within the lightguide.
[0526] In another embodiment, more than one light extraction layer
or region comprising light extraction features is used and the
light extraction layer or region may be located on one surface, two
surfaces, within the volume, within multiple regions of the volume,
or a combination of the aforementioned locations within the film,
lightguide, lightguide region, cladding, or a layer or region
disposed on or within the lightguide.
[0527] In another embodiment, surface or volumetric light
extraction features are disposed on or within the lightguide or
cladding or a region or surface thereon or between that direct at
least one selected from the group: 20%, 40%, 60%, and 80% of light
incident from within the lightguide to angles within 30 degrees
from the normal to the light emitting surface of the light emitting
device or within 30 degrees from the normal of a reflecting surface
such as a reflective spatial light modulator.
Folding and Assembly
[0528] In one embodiment, the coupling lightguides are heated to
soften the lightguides during the folding or bending step. In
another embodiment, the coupling lightguides are folded while they
are at a temperature above one selected from the group: 50 degrees
Celsius, 70 degrees Celsius, 100 degrees Celsius, 150 degrees
Celsius, 200 degrees Celsius, and 250 degrees Celsius.
Folder
[0529] In one embodiment, the coupling lightguides are folded or
bent using opposing folding mechanisms. In another embodiment,
grooves, guides, pins, or other counterparts facilitate the
bringing together opposing folding mechanisms such that the folds
or bends in the coupling lightguides are correctly folded. In
another embodiment, registration guides, grooves, pins or other
counterparts are disposed on the folder to hold in place or guide
one or more coupling lightguides or the lightguide during the
folding step. In one embodiment, at least one of the lightguide or
coupling lightguides comprises a hole and the holder comprises a
registration pin and when the pin is positioned through the hole
before and during the folding step, the lightguide or coupling
lightguide position relative to the holder is fixed in at least one
direction. Examples of folding coupling lightguides or strips for
lightguides are disclosed in International Patent Application
number PCT/US08/79041 entitled "Light coupling into illuminated
films,"
[0530] In one embodiment, the folding mechanism has an opening
disposed to receive a strip that is not to be folded in the folding
step. In one embodiment, this strip is used to pull the coupling
lightguides into a folded position, pull two components of the
folding mechanism together, align the folding mechanism components
together, or tighten the folding such that the radius of curvature
of the coupling lightguides is reduced.
[0531] In one embodiment, at least one selected from the group:
folding mechanism, relative position maintaining element, holder,
or housing is formed from one selected from the group: sheet metal,
foil, film, rigid rubber, polymer material, metal material,
composite material, and a combination of the aforementioned
materials.
Holder
[0532] In one embodiment, a light emitting device comprises a
folding mechanism which substantially maintains the relative
position of the coupling lightguides subsequent to the folding
operation. In another embodiment, the folder or housing comprises a
cover that is disposed over (such as slides over, folds over,
hinges over, clips over, snaps over, etc.) the coupling lightguides
and provides substantial containment of the coupling lightguides,
in a further embodiment, the folding mechanism is removed after the
coupling lightguides have been folded and the holding mechanism is
disposed to hold the relative position of the coupling lightguides.
In one embodiment, the holding mechanism is a tube with a circular,
rectangular, or other geometric shape cross-sectional profile which
slides over the coupling lightguides and further comprises a slit
where the coupling lightguides, light mixing region, or lightguide
exits the tube. In one embodiment, the tube is one selected from
the group: transparent, black, has inner walls with a diffuse
luminous reflectance greater than 70%, and has a gloss less than 50
in a region disposed proximate a coupling lightguide such that the
surface area of the inner tube in contact with the coupling
lightguide remains small.
[0533] In a further embodiment, a method of manufacturing a light
input coupler and lightguide comprises at least one step selected
from the group: holding the coupling lightguide, holding the
lightguide, cutting the regions in the film corresponding to the
coupling lightguides, and folding or bending the coupling
lightguides wherein the relative position maintaining element holds
the lightguide or coupling lightguide during the cutting and the
folding or bending step. In another embodiment, a method of
manufacturing a light input coupler and lightguide comprises
cutting the coupling lightguides in a film followed by folding or
bending the coupling lightguides wherein the same component holding
the coupling lightguides or lightguide in place during the cutting
also holds the coupling lightguide or lightguide in place during
the folding or bending.
[0534] In another embodiment, the relative position of at least one
region of the coupling lightguides are substantially maintained by
one or more selected from the group: wrapping a band, wire, string,
fiber, line, strap, wrap or similar tie material around the
coupling lightguides or a portion of the coupling lightguides,
disposing a housing tube, case, wall or plurality of walls or
components around a portion of the coupling lightguides, wrapping a
heat-shrinking material around the coupling lightguides and
applying heat, bonding the coupling lightguides using adhesives,
thermal bonding or other adhesive or bonding techniques in one or
more regions of the coupling lightguides (such as near the input
end, for example), clamping the lightguides, disposing a low
refractive index epoxy, adhesive, or material around, or between
one or more regions of the coupling lightguides, pressing together
coupling lightguides comprising a pressure sensitive adhesive (or
UV cured or thermal adhesive) on one or both sides. In one
embodiment, the coupling lightguide region of a film comprises a
pressure sensitive adhesive wherein after the coupling lightguides
are cut into the film with the adhesive, the coupling lightguides
are folded on top of one another and pressed together such that the
pressure sensitive adhesive holds them in place. In this
embodiment, the pressure sensitive adhesive can have a lower
refractive index than the film, and operate as cladding layer.
[0535] In another embodiment, the folder and/or holder has a
plurality of surfaces disposed to direct, align, bring the coupling
lightguides together, direct the coupling lightguides to become
parallel, or direct the input surfaces of the coupling lightguides
toward a light input surface disposed to receive light from an LED
when the coupling lightguides are translated in the folder or
holder. In one embodiment, the coupling lightguides are guided into
a cavity that aligns the coupling lightguides parallel to each
other and disposes the input edges of the coupling lightguides near
an input window. In one embodiment, the window is open, comprises a
flat outer surface, or comprises an optical outer surface suitable
for receiving light from a light source.
Hold-Down Mechanism
[0536] In one embodiment, at least one coupling lightguide
comprises at least one hook region disposed near the input surface
end of the coupling lightguide. The hook region allows a guide,
alignment mechanism, or pull-down mechanism to maintain at least
one selected from the group: the relative position of the ends or
regions near the ends of the coupling lightguides, the relative
separations of the coupling lightguides to each other in the
thickness direction of the coupling lightguide, the positions of
the coupling lightguides relative to the lightguide in the
thickness direction of the lightguide, and the positions of the end
regions or the ends of the coupling lightguides in one or more
directions in a plane substantially parallel to the lightguide. In
one embodiment, the hook region comprises at least selected from
the group: a flange, a barb, a protrusion, a hole, or an aperture
region in the coupling lightguide. In one embodiment, the
lightguide or a means for manufacturing a film-based lightguide
comprises a hold down mechanism comprising two hook regions
comprising flanges on either side of at least one coupling
lightguide wherein the flanges permit a strap, wire or other film
or object to be positioned against the hook region such that the
strap, strip, wire or other film or object substantially maintains
the relative position of the ends of the coupling lightguide in at
least one direction. In another embodiment, the hold down mechanism
comprises a physical restraining mechanism for holding or
maintaining the hold down mechanism or the hook region in at least
one direction relative to a temporary or permanent base or other
component such as holder, relative position maintaining element,
housing, thermal transfer element, guide, or tension forming
element. In another embodiment, the lightguide or a means for
manufacturing a film-based lightguide comprises a hold down
mechanism comprising a hook region comprising two holes on either
side of the coupling lightguides or near the input end of the
coupling lightguides, and the coupling lightguides may be stacked
on top of each other and on top of a base element comprising two
pins that align with the holes. The pins and holes register the
ends of the coupling lightguides and substantially maintain their
relative positions near the input end of the coupling lightguides.
In another embodiment, one or more coupling lightguides comprise a
hook region that can be removed after the hold-down mechanism
forces the coupling lightguides together. In another embodiment,
the hook region may be removed along with a portion of the end of
the coupling lightguides. In one embodiment, the hook regions and
the ends of the coupling lightguides are cut, peeled or town off
after the coupling lightguides have been strapped or physically
coupled to a base or other element. After the hook regions and the
coupling lightguides are cut from the remainder of the coupling
lightguides, the new ends of the coupling lightguides may form an
input surface or a surface suitable to optically couple to one or
more optical elements such as windows or secondary optics.
[0537] In another embodiment, one or more coupling lightguide
comprise a removable hook region comprising an aperture cut from
the lightguide that forms the light input surface for the coupling
lightguide after removing the hook region. For example, in one
embodiment, an array of coupling lightguides are cut into a film
wherein the end region of the coupling lightguide near the input
edge comprises shoulder-like flanges that extend past the average
width of the coupling lightguides and further comprises an aperture
cut that extends more than 20% of the width of the coupling
lightguides. In this embodiment, the lateral edges of the coupling
lightguides and aperture cut can be cut during the same process
step and they can both comprises high quality surface edges. When
the edge region is removed from the ends of the coupling
lightguides using the aperture cut as a separation guide after
stacking and aligning using the shoulder-like flanges, the stack of
coupling lightguides have a light input surface formed from the
collection of edges formed by the aperture cut. Similarly, pin and
hole type hook regions may be used and in one embodiment, the hook
region does not extend past the width of the coupling lightguides.
For example, holes near the width ends of the coupling lightguides
may be used as hook regions.
[0538] In another embodiment, one or more coupling lightguides is
physically coupled to a hold down mechanism and the hold down
mechanism is translated in a first direction substantially parallel
to the axis of the coupling lightguides such that the coupling
lightguides move closer together, closer to the lightguide, or
closer to the base. For example, in one embodiment, the end region
of the coupling lightguides comprises holes that are aligned onto a
pin under low tension. After the coupling lightguides are aligned
onto the pins, the pins and the base supporting the pins is
translated in a direction away from the coupling lightguides such
that the coupling lightguide pull closer toward each other and the
base.
Converting or Secondary Operations on the Film or Light Input
Coupler
[0539] In one embodiment, at least one selected from the group:
coupling lightguides, lightguide, light transmitting film,
lightguide region, light emitting region, housing, folder, and
holder component is stamped, cut, thermoformed, or painted. In one
embodiment, the cutting of the component is performed by one
selected from the group: knife, scalpel, heated scalpel, die
cutter, water jet cutter, saw, hot wire saw, laser cutter, or other
blade or sharp edge. One or more components may be stacked before
the cutting operation.
[0540] In one embodiment, the component is thermoformed (under a
vacuum, ambient pressure, or at another pressure) to create a
curved or bent region. In one embodiment, the film is thermoformed
into a curve and the coupling lightguide strips are subsequently
cut from the curved film and folded in a light input coupler.
[0541] In one embodiment, at least one edge selected from the
group: coupling lightguide, lightguide, light transmitting film,
collection of coupling lightguides, and edge of other layer or
material within the light emitting device is modified to become
more planar (closer to optically flat), roughened, or formed with a
predetermined structure to redirect light at the surface (such as
forming Fresnel refracting features on edges of the input coupling
lightguides in a region of the collection of coupling lightguides
to direct light into the coupling lightguides in a direction closer
to a direction parallel to the plane of the coupling lightguides at
the input surface (for example, forming a Fresnel collimating lens
on the surface of the collection of coupling lightguides disposed
near an LED). In one embodiment, the edge modification
substantially polishes the edge by laser cutting the edge,
mechanically polishing the edge, thermally polishing (surface
melting, flame polishing, embossing with a flat surface),
chemically polishing (caustics, solvents, methylene chloride vapor
polishing, etc.).
Reflective Coating or Element
[0542] In one embodiment, at least one region of at least one edge
selected from the group: coupling lightguide, film, and lightguide
comprises a substantially specularly reflecting coating or element
optically coupled to the region or disposed proximal to the edge.
In one embodiment, the substantially specularly reflecting element
or coating can redirect light a portion of the light exiting the
coupling lightguide, lightguide, or film edge back into the
coupling lightguide, lightguide or film at an angle that will
propagate by TIR within the lightguide. In one embodiment, the
specularly reflective coating is a dispersion of light reflecting
material disposed in an ink or other binder selected from the
group: dispersions of aluminum, silver, coated flakes, core-shell
particles, glass particles, and silica particles. In another
embodiment, the dispersion comprises particle sizes selected from
one of the group of less than 100 microns in average size, less
than 50 microns in average size, less than 10 microns in average
size, less than 5 microns in average size, less than 1 micron in
average size, less than 500 nm in average size. In another
embodiment, the dispersion comprises substantially planar flakes
with an average dimension in a direction parallel to the flake
surface selected from one of the group of less than 100 microns in
average size, less than 50 microns in average size, less than 10
microns in average size, less than 5 microns in average size, less
than 1 micron in average size, less than 500 nm in average size. In
another embodiment, the coupling lightguides are folded and stacked
and a light reflecting coating is applied in regions on the edges
of the lightguide. In another embodiment, the light reflecting
coating is applied to the tapered region of the collection of
coupling lightguides. In a further embodiment, the blade that cuts
through the film, coupling lightguide, or lightguide passes through
the film during the cutting operation and makes contact with a well
comprising reflective ink and the ink is applied to the edge when
the blade passes back by the edge of the film. In another
embodiment, a multilayer reflection film, such as a specularly
reflecting multilayer polymer film is disposed adjacent to or in
optical contact with the coupling lightguides in a region covering
at least the region near the edges of the coupling lightguides, and
the specularly reflecting multilayer polymer film is formed into
substantially a 90 bend forming a reflected side to the coupling
lightguide. The bending or folding of the reflective film may be
achieved during the cutting of the lightguide, coupling
lightguides, or tapered region of the coupling lightguides. In this
embodiment, the reflective film may be adhered or otherwise
physically coupled to the film, coupling lightguide, collection of
coupling lightguides, or lightguide and the fold creates a flat
reflective surface near the edge to reflect light back into the
lightguide, film, coupling lightguide or collection of coupling
lightguides. The folding of the reflective film may be accomplished
by bending, pressure applied to the film, pressing the lightguide
such that a wall or edge bends the reflective film. The reflective
film may be disposed such that it extends past the edge prior to
the fold. The folding of the reflective film may be performed on
multiple stacked edges substantially simultaneously.
[0543] The following are more detailed descriptions of various
embodiments illustrated in the Figures.
[0544] FIG. 1 is a top view of one embodiment of a light emitting
device 100 comprising a light input coupler 101 disposed on one
side of a film-based lightguide. The light input coupler 101
comprises coupling lightguides 104 and a light source 102 disposed
to direct light into the coupling lightguides 104 through a light
input surface 103 comprising one or more input edges of the
coupling lightguides 104. In one embodiment, each coupling
lightguide 104 includes a coupling lightguide terminating at a
bounding edge. Each coupling lightguide is folded such that the
bounding edges of the coupling lightguides are stacked to form the
light input surface 103. The light emitting device 100 further
comprises a lightguide region 106 comprising a light mixing region
105, a lightguide 107, and a light emitting region 108. Light from
the light source 102 exits the light input coupler 101 and enters
the lightguide region 106 of the film. This light spatially mixes
with light from different coupling lightguides 104 within the light
mixing region 105 as it propagates through the lightguide 107. In
one embodiment, light is emitted from the lightguide 107 in the
light emitting region 108 due to light extraction features (not
shown).
[0545] FIG. 2 is a perspective view of one embodiment of a light
input coupler 200 with coupling lightguides 104 folded in the -y
direction and stacked in the z direction (direction of the stack).
Light from the light source 102 is directed into the light input
surface 103 comprising input edges 204 of the coupling lightguides
104. A portion of the light from the light source 102 propagating
within the coupling lightguides 104 with a directional component in
the +y direction will reflect in the +x and -x directions from the
lateral edges 203 of the coupling lightguides 104 and will reflect
in the -z and -z directions from the top and bottom surfaces of the
coupling lightguides 104. The light propagating within the coupling
lightguides is redirected by the folds 201 in the coupling
lightguides 104 toward the -x direction.
[0546] FIG. 3 is a top view of one embodiment of a light emitting
device 300 with three light input couplers 101 on one side of the
lightguide region 106 comprising the light mixing region 105, a
lightguide 107, and the light emitting region 108.
[0547] FIG. 4 is a top view of one embodiment of a light emitting
device 400 with two light input couplers 101 disposed on opposite
sides of the lightguide 107. In certain embodiments, one or more
input couplers 101 may be positioned along one or more
corresponding sides of the lightguide 107.
[0548] FIG. 5 is a top view of one embodiment of a light emitting
device 500 with two light input couplers 101 disposed on the same
side of the lightguide region 106. The light sources 102 are
oriented substantially with the light directed toward each other in
the -y and -y directions.
[0549] FIG. 6 is a cross-sectional side view of one embodiment of a
light emitting device 600 defining a region 604 near a
substantially planar light input surface 603 comprised of planar
edges of coupling lightguides 104 disposed to receive light from a
light source 102. The coupling lightguides comprise core regions
601 and cladding regions 602. A portion of the light from the light
source 102 input into the core region 601 of the coupling
lightguides 104 will totally internally reflect from the interface
between the core region 601 and the cladding region 602 of the
coupling lightguides 104. In the embodiment shown in FIG. 6, a
single cladding region 602 is positioned between adjacent core
regions 601. In another embodiment, two or more cladding regions
602 are positioned between adjacent core regions 601.
[0550] FIG. 7 is a cross-sectional side view of one embodiment of a
light emitting device 700 defining a region 704 near a light input
surface of the light input coupler 101 having one or more planar
surface features 701 substantially parallel to stack direction (z
direction as shown in FIG. 7) of the coupling lightguides 104, one
or more refractive surface features 702, and one or more planar
input surfaces 703 and a bevel formed on an opposite surface of the
coupling lightguide 104 that totally internally reflects a portion
of incident light into the coupling lightguide 104 similar to a
hybrid refractive-TIR Fresnel lens.
[0551] FIG. 8 is a cross-sectional side view of one embodiment of a
light emitting device 800 defining a region 802 near a light input
surface of the light emitting device 800. The coupling lightguides
104 are optically coupled to the light source 102 by an optical
adhesive 801 or other suitable coupler or coupling material. In
this embodiment, less light from the light source 102 is lost due
to reflection (and absorption at the light source or in another
region) and the positional alignment of the light source 102
relative to the coupling lightguides 104 is easily maintained.
[0552] FIG. 9 is a cross-sectional side view of one embodiment of a
light emitting device 900 defining a region 903 near a light input
surface of the light emitting device 900. In this embodiment, the
coupling lightguides 104 are held in place by a sleeve 901 with an
outer coupling surface 902 and the edge surfaces of the coupling
lightguides 104 are effectively planarized by an optical adhesive
801 between the ends of the coupling lightguides and the sleeve 901
with the outer surface 902 adjacent the light source 102. In this
embodiment, the surface finish of the cutting of the coupling
lightguides is less critical because the outer surface 902 of the
sleeve 901 is optically coupled to the edges using an optical
adhesive 801 which reduces the refraction (and scattering loss)
that could otherwise occur at the air-input edge interface of the
input edge due to imperfect cutting of the edges. In another
embodiment, an optical gel, a fluid or a non-adhesive optical
material may be used instead of the optical adhesive to effectively
planarize the interface at the edges of the coupling lightguides.
In certain embodiments, the difference in the refractive index
between the optical adhesive, the optical gel, the fluid, or the
non-adhesive optical material and the core region of the coupling
lightguides is less than one selected from group of 0.6, 0.5, 0.4,
0.3, 0.2, 0.1, 0.05, and 0.01. In one embodiment, the outer surface
902 of the sleeve 901 is substantially flat and planar.
[0553] FIG. 10 is a top view of one embodiment of a light emitting
backlight 1000 configured to emit red, green, and blue light. The
light emitting backlight 1000 includes a red light input coupler
1001, a green light input coupler 1002, and a blue light input
coupler 1003 disposed to receive light from a red light source
1004, a green light source 1005, and a blue light source 1006,
respectively. Light from each of the light input couplers 1001,
1002, and 1003 is emitted from the light emitting region 108 due to
the light extraction features 1007 which redirect a portion of the
light to angles closer to the surface normal within the lightguide
region 106 such that the light does not remain within the
lightguide 107 and exits the light emitting device 1000 in a light
emitting region 108. The pattern of the light extraction features
1007 may vary in one or more of size, space, spacing, pitch, shape,
and location within the x-y plane or throughout the thickness of
the lightguide in the z direction.
[0554] FIG. 11 is a cross-sectional side view of one embodiment of
a light emitting device 1100 comprising the light input coupler 101
and the lightguide 107 with a reflective optical element 1101
disposed adjacent a the cladding region 602 and a light source 1102
with an optical axis in the +y direction disposed to direct light
into the coupling lightguides 104. Light from the light source 1102
propagates through the coupling lightguides 104 within the light
input coupler 101 and through the light mixing region 105 and the
light output region 108 within the lightguide region 106. Referring
to FIG. 11, a first portion of light 1104 reaching the light
extraction features 1007 is redirected toward the reflecting
optical element 1101 at an angle less than the critical angle such
that it can escape the lightguide 107, reflect from the reflective
optical element 1101, pass back through the lightguide 107, and
exit the lightguide 107 through the light emitting surface 1103 of
the light emitting region 108. A second portion of light 1105
reaching the light extraction features 1007 is redirected toward
the light emitting surface 1103 at an angle less than the critical
angle, escapes the lightguide 107, and exits the lightguide 107
through the light emitting surface 1103 of the light emitting
region 108.
[0555] FIG. 12 is a cross-sectional side view of one embodiment of
a light emitting display 1200 illuminated by a red lightguide 1201,
a green lightguide 1202, and a blue lightguide 1203. The locations
of the pixels of the display panel 1204 with corresponding red
pixels 12010, green pixels 1209, and blue pixels 1208 correspond to
light emitting regions of the lightguide separated by color. In
this embodiment, the light extracting features 1205 within the red
lightguide 1201 substantially correspond in the x-y plane to the
red pixels 1210 of the display panel 1204 driven to display red
information. Similarly, the green light extracting features 1206
within the green lightguide 1202 and the blue light extracting
features 1207 within the blue lightguide 1203 substantially
correspond in the x-y plane to the green pixels 1209 and the blue
pixels 1208, respectively, of the display panel 1204 driven to
display corresponding green and blue information. In another
embodiment, the display panel 1204 is a spatial light modulator
such as a liquid crystal panel, electrophoretic display, MEMS-based
display, ferroelectric liquid crystal panel, or other spatial light
modulating device such as known in the display industry. In another
embodiment, the display panel 1204 further comprises color filters
within the pixel regions to further reduce crosstalk from
lightguide illumination reaching the pixel from neighboring light
extracting features. In another embodiment, the lightguides are
optically coupled to each other and the reflecting optical element
is a specularly reflecting optical element. In a further
embodiment, the liquid crystal panel is a transparent LCD (such as
a vertical alignment type from Samsung Electronics with a
transparent cathode) and there is no reflecting optical element on
the opposite side of the lightguides than the display panel. In
this embodiment, the display and backlight are substantially
transparent and "see-through" with an ASTM D1003 total luminous
transmittance greater than one selected from the group: 20%, 30%,
40%, and 50%.
[0556] FIG. 13 is a cross-sectional side view of one embodiment of
a color sequential display 1300 comprising a color sequential
display panel 1301 and a red, green, and blue color sequential
light emitting backlight 1302 comprising a film-based lightguide.
In this embodiment, red, green, and blue light from red, green and
blue light sources (not shown in FIG. 13) is coupled into the
lightguide through one or more light input couplers (not shown in
FIG. 13). The light sources are driven in a color sequential mode
and the pixel regions of the display panel 1301 are switched
accordingly to display the desired color information. In one
embodiment, the display panel 1301 is a spatial light modulator
without color filters. FIG. 14 is a cross-sectional side view of
one embodiment of a spatial display 1400 comprising a spatial light
modulator 1401 and a film-based backlight 1402 emitting light from
light sources of different colors. In one embodiment, the spatial
display is a liquid crystal display. In another embodiment, the
spatial light modulator is a liquid crystal panel. In a further
embodiment, the film-based backlight emits light from one selected
from the group: red, green, and blue; white and red; red, green,
blue, and yellow; red, green, blue, yellow, and cyan; and cyan,
yellow, and magenta.
[0557] FIG. 15 is a cross-sectional side view of one embodiment of
a spatial display 1500 comprising a spatial light modulator 1401
and a him-based backlight 1501 emitting white light.
[0558] FIG. 16 is a cross-sectional side view of one embodiment of
a spatial display 1600 comprising a spatial light modulator 1401
and a backlight 1601 comprising a film-based lightguide 107
emitting blue light, UV light, or a combination of blue and UV
light. A portion of this light passes through a wavelength
converting layer 1602 and is converted to light of a second color.
In one embodiment, the wavelength converting layer 1602 is a
phosphor film. In another embodiment, the wavelength converting
layer 1602 is a layer comprising quantum dots. FIG. 17 is a cross
sectional side view of one embodiment of a light emitting display
1700 illuminated by a backlight 1710 comprising a plurality of
lightguides emitting different colored light in predetermined
spatial patterns. The display panel 1730 is illuminated by a red
film-based lightguide 1702, a green film-based lightguide 1703, and
a blue film-based lightguide 1704 optically coupled to each other
and the display panel 1730 by an optical adhesive 1701 with a
refractive index lower than the refractive index of the lightguide.
In one embodiment, the refractive index of the optical adhesive
1701 is less than the refractive index of the lightguides (1702,
1703, and 1704) by one selected from the group: 0.5, 0.4, 0.3, 0.2,
0.1, 0.05 and 0.01. The red pixels 1721, green pixels 1722, and the
blue pixels 1723 of the display panel 1730 correspond to the tight
emitting regions of the lightguides separated by color. In this
embodiment, the tight extracting features 1711 within the red
lightguide 1702 substantially correspond in the x-y plane to the
red pixels 1721 of the display panel 1730 driven to display red
information. Similarly, the green light extracting features 1712
within the green lightguide 1703 and the blue light extracting
features 1713 within the blue lightguide 1704 substantially
correspond in the x-y plane to the green pixels 1722 and the blue
pixels 1723, respectively, of the display panel 1730 driven to
display corresponding green and blue information. In one
embodiment, the reflective optical element 1101 is specularly
reflecting. In another embodiment, the total thickness of the red,
green, and blue lightguides (1702, 1703, 1704) and the optical
adhesive layers 1701 disposed between the red, green, and blue
lightguides (1702, 1703, 1704) is less than 100 microns. In another
embodiment, the red, green, and blue lightguides 1702, 1703, and
1704 are formed by co-extruding the lightguide film layers with low
refractive index layers 1701 between them. Similarly, a yellow
lightguide may be added, a cyan lightguide may be added or other
combinations of colors of lightguides may be used to increase the
color gamut of the display or provide a different predetermined
color gamut such as one suitable for a night vision compatible
display.
[0559] FIG. 18 is a top view of one embodiment of a light emitting
device 1800 comprising two light input couplers with two arrays of
coupling lightguides 104 and two light sources 102 on the same edge
in the middle region oriented in opposite directions. As shown in
FIG. 18, the +y and -y edges of the light emitting device 1800 may
be very close to the border of the light emitting region 108
because the light sources 102, including LEDs, do not extend past
the bottom edge of the light emitting region 108 as the light
source 102 in the embodiment shown in FIG. 1 does. Thus, a TV for
example, illuminated by the light emitting device 1800 of shown in
FIG. 18 could have a light emitting display area extending less
than 2 millimeters from the edge of the light emitting device 1800
in the +y and -y directions. In the embodiment shown in FIG. 18,
the light source 102 is disposed substantially in a middle region
of the light emitting region 108 between the +y and edges of the
light emitting device 1800.
[0560] FIG. 19 is a top view of one embodiment of a light emitting
device 1900 comprising one light input coupler with coupling
lightguides 104 folded in the +y and -y directions and then folded
in the +z direction (out of the page in the drawing) toward a
single light source 102.
[0561] FIG. 20 is a cross-sectional side view of one embodiment of
a spatial display 2000 with a rear polarizer 2002 of a liquid
crystal display panel 2001 optically coupled to a film-based
lightguide backlight 1402 using an optical adhesive 801. The liquid
crystal display panel 2001 further comprises two display substrates
2003 (glass or a polymer film for example), liquid crystal material
2004, and a front polarizer 2005. The liquid crystal display panel
may further comprise one or more of the following: other suitable
films, materials and/or layers such as compensation films,
alignment layers, color filters, coatings, transparent conductive
layers, TFTs, anti-glare films, anti-reflection films, etc. as is
commonly known in the display industry.
[0562] FIG. 21 is a cross-sectional side view of one embodiment of
a spatial display 2100 comprising a frontlight 2103 optically
coupled to a reflective spatial light modulator 2101. The
frontlight 2103 comprises a film-based lightguide 2102 with light
extracting features 1007 that direct light to the reflective
spatial light modulator 2101 at angles near the surface normal of
the reflective spatial light modulator 2101. In one embodiment, the
reflective spatial light modulator 2101 is an electrophoretic
display, a microelectromechanical systems (MEMS)-based display, or
a reflective liquid crystal display. In one embodiment, the light
extraction features 1007 direct one of 50%, 60%, 70%, 80%, and 90%
of the light exiting the frontlight 2103 toward the reflective
spatial light modulator 2101 within an angular range of 60 degrees
to 120 degrees from the light emitting surface of the frontlight
2103.
[0563] FIG. 22 is a cross-sectional side view of one embodiment of
a spatial display 2200 comprising a frontlight 2202 with an air gap
between a film-based lightguide 2201 disposed adjacent to a
reflective spatial light modulator 2101. In one embodiment, the
reflective spatial light modulator 2101 comprises one or more color
filters. In another embodiment, the reflective spatial light
modulator 2101 comprises one or more spatial regions that reflect a
wavelength bandwidth (FWHM) less than 300 nm and the spatial
regions reflect more than one color in a spatial pattern, such as
in an interferometric modulator or IMOD device. In another
embodiment, the film-based lightguide 2201 is disposed to receive
light from two or more light sources with different colors such
that the illumination is color sequential synchronized with the
reflective spatial light modulator 2101 resulting in a full-color
display.
[0564] FIG. 23 is a cross-sectional side view of one embodiment of
a spatial display 2300 comprising a frontlight 2302 with light
extraction features 1007 on a side 2303 of the lightguide 2301
nearest the reflective spatial light modulator 2101 optically
coupled to a reflective spatial light modulator 2101 using an
optical adhesive 801.
[0565] FIG. 24 is a cross-sectional side view of one embodiment of
a spatial display 2400 comprising a frontlight 2404 comprising a
film-based lightguide 107 disposed within a reflective spatial
light modulator 2401 comprising a reflective component layer 2402.
In one embodiment, the film-based lightguide 107 is a substrate for
the reflective spatial light modulator 2401. In another embodiment,
the intensity of light for the reflective spatial light modulator
24101 is controlled by frustrating the total internal reflection
occurring within the film-based lightguide 107. In another
embodiment, the intensity of light for a transmissive spatial light
modulator (not shown) is controlled by frustrating the total
internal reflection occurring within the film-based lightguide.
[0566] FIG. 25 is a cross-sectional side view of a region of one
embodiment of a light emitting device 2500 comprising a stack of
coupling lightguides 104 disposed adjacent a light source 102 with
a substrate 2502 and a light collimating optical element 2501. In
this embodiment, the light collimating optical 2501 element
collimates light from the light source in a first plane (such as
the x-z plane in the drawing) and second plane (y-x plane where the
y-direction extends into the page) orthogonal to the first plane.
In one embodiment, the collimating optical element 2501 is a lens
which refracts and totally internally reflects light to collimate
light from a light emitting diode.
[0567] FIG. 26 is a perspective view of one embodiment of a light
emitting device 2600 comprising a light source 102 and coupling
lightguides 104 oriented at an angle to the x, y, and z axes. The
coupling lightguides 104 are oriented at a first redirection angle
2601 from the +z axis (light emitting device optical axis), a
second redirection angle 2602 from the +x direction, and a third
redirection angle 2603 from the +y direction. In another
embodiment, the light source optical axis and the coupling
lightguides 104 are oriented at a first redirection angle 2601 from
the +z axis (light emitting device optical axis), a second
redirection angle 2602 from the +x direction, and a third
redirection angle 2603 from the +y direction.
[0568] FIG. 27 is a perspective view of one embodiment of a light
emitting device 2700 comprising coupling lightguides 104 that are
optically coupled to a surface of a lightguide 107. In one
embodiment, the coupling lightguides optically coupled to the
lightguide have a thickness less than one selected from the group:
40%, 30%, 20%, 10%, and 5% of the thickness of the lightguide.
[0569] FIG. 28 is a perspective view of one embodiment of a light
emitting device 2800 comprising coupling lightguides 104 that are
optically coupled to an edge 2801 of a lightguide 107. In one
embodiment, the coupling lightguides 104 optically coupled to the
edge 2801 of the lightguide 107 have a thickness less than one
selected from the group: 90%, 80%, 70%, 60%, 50%, 40%, 30%, 20%,
and 10% of the thickness of the lightguide 107.
[0570] FIGS. 29a, 29b, 29c, 29d, and 29e illustrate one embodiment
of a method of manufacturing a lightguide 107 with continuously
coupled lightguides 104 using a light transmitting film. FIG. 29a
is a perspective view of one embodiment of a lightguide 107
continuously coupled to each coupling lightguide 104 in an array of
coupling lightguides 104. The array of coupling lightguides 104
comprise linear fold regions 2902 substantially parallel to each
other which further comprise relative position maintaining elements
2901 disposed within the linear fold regions 2902. In the
configuration shown in FIG. 29a, the array of coupling lightguides
are substantially within the same plane (x-y plane) as the
lightguide 107 and the coupling lightguides 104 are regions of a
light transmitting film. The total width, W.sub.t, of the array of
the coupling lightguides in a direction substantially parallel to
the linear fold regions 2902 is shown in FIG. 29a. In the
embodiment shown in FIG. 29a, the coupling lightguides have
substantially the same width, W.sub.s, in a direction 2906 parallel
to the linear fold region. The direction 2903 normal to a film
surface 2980 at the linear fold region 2902 is shown in FIG.
29a.
[0571] As shown in FIG. 29b, the linear fold regions 2902 are
translated with respect to each other from their locations shown in
FIG. 29a. The distance between the two linear fold regions 2902 of
the array of coupling lightguides 104 in a direction 2903 (parallel
to the z direction) perpendicular to the light transmitting film
surface 2980 at the linear fold region 2902 is increased. In
addition, as shown in FIG. 29b, the distance between the linear
fold regions 2902 of the array of coupling lightguides 104 in a
direction (y direction) substantially perpendicular to the
direction 2906 of the linear fold region 2902 and parallel to the
light transmitting film surface 2980 (x-y plane) at the linear fold
region 2902 is decreased.
[0572] As shown in FIG. 29c, the linear fold regions 2902 are
translated with respect to each other from their locations shown in
FIG. 29b. In FIG. 29c, the distance between the linear fold regions
2902 of the array of coupling lightguides 104 in a direction (x
direction) substantially parallel to the direction 2906 of the
linear fold regions 2902 and parallel to the light transmitting
film surface 2980 at the linear fold regions 2902 is increased.
[0573] FIG. 29d illustrates further translation of the linear fold
regions 2902 where the distance between the linear fold regions
2902 of the array of coupling lightguides 104 in a direction (x
direction) substantially parallel to the direction 2906 of the
linear fold regions 2902 and parallel to the light transmitting
film surface 2980 at the linear fold regions 2902 is increased and
the distance between the linear fold regions 2902 of the array of
coupling lightguides 104 in a direction 2903 perpendicular to the
light transmitting film surface 2980 at the linear fold region 2902
is decreased.
[0574] As shown in FIG. 29e, the linear fold regions 2902 are
translated with respect to each other from their locations shown in
FIG. 29d. In FIG. 29e, the distance between the linear fold regions
2902 of the array of coupling lightguides 104 in a direction (x
direction) substantially parallel to the direction 2906 of the
linear fold regions 2902 and parallel to the light transmitting
film surface 2980 at the linear fold regions 2902 is further
increased from that of FIG. 29d and the distance between the linear
fold regions 2902 of the array of coupling lightguides 104 in a
direction 2903 perpendicular to the light transmitting film surface
2980 at the linear fold region 2902 is further decreased over that
of FIG. 29d.
[0575] As a result of the translations of the linear fold regions
2902 as shown FIGS. 29a-e, corresponding edges 2981 of the linear
fold regions 2902 are separated by a distance, D. In one
embodiment, the distance, D, is at least equal to the total width,
W.sub.t, of the array of the coupling lightguides 104 in a
direction substantially parallel to the linear fold region 2902 In
another embodiment, D=N.times.W.sub.s, where the array of coupling
lightguides 104 comprise a number, N, of coupling lightguides that
have substantially the same width, W.sub.s, in a direction parallel
to the linear fold region 2902. The array of coupling lightguides
104 disposed substantially one above another may be cut along a
first direction 2904 to provide an array of input edges of the
coupling lightguides 104 that end in substantially one plane
perpendicular to the linear fold regions 2902. The cut may be at
other angles and may include angled or arcuate cuts that can
provide collimation or light redirection of light from a light
source disposed to couple light into the input surface of the
coupling lightguides.
[0576] In a further embodiment, a method of manufacturing a light
input coupler and lightguide comprises cutting the coupling
lightguides such that two input couplers and two lightguides are
formed from the same film. For example, by cutting the coupling
lightguides along the direction 2904, the light transmitting film
can be divided into two parts, each comprising a light input
coupler and a lightguide.
[0577] FIG. 30 is a cross-sectional side view of a region of one
embodiment of a reflective display 3000 comprising a backlight 3028
with light extraction features 1007 within the film-based
lightguide disposed between two cladding layers 602. The backlight
3028 is disposed between the light modulating pixels 3002 and the
reflective element 3001 within the reflective display 3000. The
light modulating pixels 3002 are disposed between the red, green,
and blue color filters 2822 and the backlight 3028. Ambient light
3003 exterior to the display 3000 propagates through the substrate
2823, through the color filters 2822, through the light modulating
pixels 3002, through the backlight 3028, and reflects from the
reflective element 3001 back through the backlight 3028, the light
modulating pixels 3002, the color filter 2822, the substrate 2823,
and exits the reflective display 3000. Light 3004 propagating
within the core region 601 of the backlight 3028 is redirected by
the light extraction features 1007 toward the reflective element
3001. This light reflects back through the backlight 3028, the
light modulating pixels 3002, the color filters 2822 and the
substrate 2823 before exiting the reflective display 3000. In this
embodiment, the backlight 3028 is within a reflective spatial light
modulator 3030. In one embodiment, for example without limitation,
the light modulating pixels comprise liquid crystal materials, the
reflective display further comprises polarizers, and the reflective
layer is a reflective coating on an outer surface of the cladding
layer.
[0578] FIG. 31 is a top view of one of an input coupler and
lightguide 3100 with coupling lightguides 104 wherein the array of
coupling lightguides 104 has non-parallel regions. In the
embodiment illustrated in FIG. 31, the coupling lightguides 104
have tapered region 3101 comprising light collimating edges 3181
and linear fold regions 2902 substantially parallel to each other.
In another embodiment, the coupling lightguides 104 have
non-constant separations. In another embodiment, a method for
manufacturing a lightguide 3100 with coupling lightguides 104
having a tapered regions 3101 of the coupling lightguides 104
includes cutting the coupling lightguides in regions 3103 disposed
at or near the tapered region 3101 such that when the array of
coupling lightguides 104 are folded, the coupling lightguides 104
overlap to form a profiled, non-planar input surface that is
capable of redirecting light input through the light input surface
so that the light is more collimated.
[0579] FIG. 32 is a perspective view of a portion of the lightguide
3100 with coupling lightguides 104 shown in FIG. 31. The coupling
lightguides 104 have been cut in regions 3103 (shown in FIG. 31)
disposed near the tapered region 3101 and folded such that the
tapered regions 3101 overlap to form a profiled light collimating
edges 3181 that are capable of redirecting light input through the
light input surface 103 so that the light is more collimated in the
x-y plane within the film-based lightguide 107.
[0580] FIG. 33 is a perspective view of one embodiment of a light
input coupler and lightguide 3300 comprising a relative position
maintaining element 3301 disposed proximal to a linear fold region
2902. In this embodiment, the relative position maintaining element
3301 has a cross-sectional edge 2971 in a plane (x-y plane as
shown) parallel to the light transmitting film surface 2970
disposed proximal to the linear fold region 2902 that comprises a
substantially linear section 3303 oriented at an angle 3302 greater
than 10 degrees to the direction 2906 parallel to the linear fold
region 2902 for at least one coupling lightguide 104. In one
embodiment, a substantially linear section 3303 is disposed at an
angle of about 45 degrees to a direction parallel to the linear
fold region 2902.
[0581] FIGS. 34 and 35a are top views of certain embodiments of
light input couplers and lightguides 3400 and 3500, respectively,
configured such that a volume and/or a size of the overall device
is reduced while retaining total internal reflection (TIR) light
transfer from the light source (not shown) into the lightguide. In
FIG. 34, the light input coupler and lightguide 3400 comprises
bundles of coupling lightguides (3401a, 3401b) that are folded
twice 3402 and recombined 3403 in a plane substantially parallel to
the film-based lightguide 107.
[0582] FIG. 35a is a top view of one embodiment of a light emitting
device with a light input coupler and lightguide 3500 that
comprises bundles (3401a, 3401b) that are folded upwards 3501 (+z
direction) and combined in a stack 3502 that is substantially
perpendicular to the plane of the film-based lightguide 107.
[0583] FIG. 35b is a perspective view of the bundles (3401a, 3401b)
of coupling lightguides folded upward 3501 in the +z direction. In
another embodiment, the bundles are folded downwards (-z
direction).
[0584] FIG. 36 is a top view of one embodiment of a light emitting
device 3600 comprising a lenticular lens array film 36101 with a
linear array of lenticules 3602 wherein the lightguide region 106,
light mixing region 105, and the light input coupler 101 are formed
from the lenticular lens array film 3601
[0585] FIG. 37 is a cross-sectional side view of one embodiment of
a lenticular lens array film 3601 comprising light extraction
features 1007 disposed on the core region 601 beneath the
lenticules 3602 and the cladding layer 602. A portion of the light
3702 propagating in the x direction and the y direction within the
core region 601 is directed into angles smaller than the critical
angle for the core-cladding interface by the light extraction
feature 1007 and passes through the cladding region 602 and the
lenticules 3602 where it is refracted by the lenticule 3602
producing substantially collimated light 3701.
[0586] FIG. 38 is a cross-sectional side view of one embodiment of
a display 3800 comprising a multi-layer lenticular lens array film
3808 comprising a red lightguide core region 3801 illuminated by a
red LED (not shown), a green lightguide core region 3802
illuminated by a green LED (not shown), and a blue lightguide core
region 3803 illuminated by a blue LED (not shown) and cladding
regions 602. Red light 3804 incident on the light extraction
feature 1007 will be reflected toward the lenticules 3602 which are
light redirecting elements that substantially collimate the light
received from near their focal point and direct the light toward
the pixels or sub-pixels corresponding to the red pixels 3810 of
the display. Similarly, green light 3805 incident on the light
extraction feature 1007 will be reflected toward the lenticules
3602, collimated and directed toward the pixels or sub-pixels
corresponding to the green pixels 3811 of the display, and blue
light 3806 incident on the light extraction feature 1007 will be
reflected toward the lenticules 3602, collimated and directed by
the lenticules 3602 toward the pixels or sub-pixels corresponding
to the blue pixels 3812 of the display. The focal lengths of the
lenticules 3602 may be designed to be at the plane of the middle
light extraction feature or another plane so as to optimize
collimation of light. By using a common focal point, the lenticular
lens array film is simpler to manufacture. In another embodiment,
the focal point of the lenticular lens array film varies in the y
direction due to changing radii of curvature in the y direction. In
a further embodiment, the focal point of the lenticular lens array
film varies by height of the lenticule (constant radii of curvature
but varying the height of the lenticules). As shown in FIG. 38, the
cross section is of a lenticular lens array film 3808; however,
similar cross-sections can be envisioned for microlens arrays which
vary in two dimensional arrangements.
[0587] The display 3800 shown in FIG. 38 produces substantially
collimated light output 3807 incident upon a liquid crystal display
panel 3809 comprising red pixel regions 3810, green pixel regions
3811, and blue pixel regions 3812. In this embodiment, the close
proximity of the lightguides to the liquid crystal display panel
and the collimation can permit the elimination of color filters in
the display panel. Color filters may be used to further eliminate
any crosstalk or color filters permitting more light through may be
used. The lightguides may be formed separately and combined
together, then aligned with the liquid crystal panel, the
lightguides may be individually aligned with the panel, or the
lightguides may be formed at substantially the same time and
subsequently aligned to the panel, or the lightguides may be
coupled to the light panel and the light extraction features
subsequently formed. In an alternative embodiment, the lightguide
does not comprise a lenticular lens array film or light redirecting
element.
[0588] FIG. 39 is a top view of an embodiment of a light emitting
device 3900 comprising a light input coupler 3908 comprising a
lightguide 3903 and a single coupling lightguide comprising fold
regions 3909 defined by fold lines 3902, a reflective edge 3904 and
a light input edge 204 disposed between a first reflective surface
edge 3906 and a second reflective surface edge 3907 within a single
film. The film of the light input coupler 3908 is folded along fold
lines 3902 such that the fold regions 3909 substantially overlay
each other and the light source 102 couples light into each light
input edge 204. The optical system is shown "un-folded" in FIG. 39
and the light sources 3901 correspond to the location of the light
source 102 relative to the fold regions 3909 when the film is
folded. As shown in FIG. 39, light 3905 from the light source 102
(and the light sources 3901 when folded) totally internally
reflects from the reflective edge 3904 which is angled toward the
light emitting region 108 of the lightguide 3903. The first
reflective surface 3906 and the second reflective surface 3907 are
formed by shaped edges (angled or curved for example) in the film
and serve to redirect a portion of light from the light sources
(102 and 3901) into the lightguide at angles which totally
internally reflect from the angled edge 3904.
[0589] FIG. 40 is a perspective view of the lightguide 3903 and the
light input coupler 3908 comprising a light source 102 and coupling
lightguide of FIG. 39 as the film is being folded along the fold
lines 3902 in the direction 4001 represented in the figure. The
fold regions 3909 substantially layer upon each other such that the
light input edges 204 stack and align to receive light from the
light source 102.
[0590] FIG. 41 is a perspective view of the lightguide 3903 and the
light input coupler 3908 of FIG. 39 folded and comprising a
coupling lightguide formed from overlapping fold regions 3909 of a
film lightguide 3903. The fold regions 3909 substantially layer
upon each other such that the light input edges 204 stack and align
to receive light from the light source 102.
[0591] FIG. 42 is an elevated view of an embodiment film-based
lightguide 4205 comprising a first light emitting region 4201
disposed to receive light from a first set of coupling lightguides
4203 and a second light emitting region 4202 disposed to receive
light from a second set of coupling lightguides 4204. The light
emitting regions are separated from each other in the y direction
by a distance "SD" 4206. The free ends of the sets of coupling
lightguides 4203 and 4204 can be folded toward the -y direction
such that both sets substantially overlap as shown in FIG. 43.
[0592] FIG. 43 is an elevated view of the film-based lightguide
4205 of FIG. 42 wherein the coupling lightguides 4203 are folded
such that they substantially overlap and form a light input surface
103. In this embodiment, a single light source (not shown) may
illuminate two separate light emitting regions within the same
film. In another embodiment, two separated film-based lightguides
have separate light input couplers which are folded and the light
input edges are brought together to form a stack of coupling
lightguides disposed to receive light from a light source. This
type of configuration may be useful, for example, where the first
light emitting region backlights a LCD and the second light
emitting region illuminates a keypad on a mobile phone device.
[0593] FIG. 44 is a cross-sectional side view of one embodiment of
a light emitting device 4400 with optical redundancy comprising two
lightguides 107 stacked in the z direction. Light sources and
coupling lightguides within the holders 4402 arranged substantially
adjacent in the y direction direct light into core regions 601 such
that light 4401 is output from the light emitting region 108 from
each lightguide 107.
[0594] FIG. 45 is a cross-sectional side view of one embodiment of
a light emitting device 4500 with a first light source 4501 and a
second light source 4502 thermally coupled to a first thermal
transfer element 4505 (such as a metal core printed circuit board
(PCB)) and thermally insulated (physically separated by an air gap
in the embodiment shown) from a second thermal transfer element
4506 that is thermally coupled to a third light source 4503 and a
fourth light source 4504. The first light source 4501 and the third
light source 4503 are disposed to couple light into a first light
input coupler 4507 and the second light source 4502 and the fourth
light source 4504 are disposed to couple light into a second light
input coupler 4508. In this embodiment, the heat dissipated from
the first light source 4501 is dissipated along the first thermal
transfer element 4505 in the x direction toward the second light
source 4502 such that heat from the first light source 4501 does
not substantially increase the temperature at the third light
source 4503 by conduction.
[0595] FIG. 46 is a top view of one embodiment of a light emitting
device 4600 comprising a plurality of coupling lightguides 104 with
a plurality of first reflective surface edges 3906 and a plurality
of second reflective surface edges 3907 within each coupling
lightguide 104. In the embodiment shown in FIG. 46, three light
sources 102 are disposed to couple light into respective light
input edges 204 at least partially defined by respective first
reflective surface edges 3906 and second reflective surface edges
3907.
[0596] FIG. 47 is an enlarged perspective view of the coupling
lightguides 104 of FIG. 46 with the light input edges 204 disposed
between the first reflective surface edges 3906 and the second
reflective surface edges 3907. The light sources 102 are omitted in
FIG. 47 for clarity.
[0597] FIG. 48 is a cross-sectional side view of the coupling
lightguides 104 and the light source 102 of one embodiment of a
light emitting device 4800 comprising index matching regions 4801
disposed between the core regions 601 of the coupling lightguides
104 in the index-matched region 4803 of the coupling lightguides
104 disposed proximate the light source 102. The light source 102
is positioned adjacent the coupling lightguides 104 and the high
angle light 4802 from the light source 102 propagates through the
coupling lightguides 104 and the index matching region 4801 and is
coupled into the coupling lightguides 104 at a location distant
from the light input edge 204 of the coupling lightguides 104. In
the embodiment shown in FIG. 48, the light from the light source
102 is coupled into more coupling lightguides because the light,
for example at 60 degrees from the optical axis 4830 of the light
source 102 propagates into a core region 601 near the light source,
propagates through the index matching region 4801, and totally
internally reflects in a core region 601 further away from the
light source 102. In this embodiment, a portion of the light is
coupled into the outer coupling lightguides 104 that would not
normally receive the light if there were cladding present at or
near the light input edge 204.
[0598] FIG. 49 is a top view of one embodiment of a film-based
lightguide 4900 comprising an array of tapered coupling lightguides
4902 formed by cutting regions in a lightguide 107. The array of
tapered coupling lightguides 4902 extend in a first direction (y
direction as shown) a dimension, d1, which is less than a parallel
dimension, d2, of the light emitting region 108 of the lightguide
107. A compensation region 4901 is defined within the film-based
lightguide 4900 which does not include tapered coupling lightguides
4902 (when the tapered coupling lightguides 4902 are not folded or
bent). In this embodiment, the compensation region provides a
volume having sufficient length in the y direction to place a light
source (not shown) such that the light source does not extend past
the lower edge 4903 of the lightguide 107. The compensation region
4901 of the light emitting region 108 may have a higher density of
light extraction features (not shown) to compensate for the lower
input flux directly received from the tapered coupling lightguides
4902 into the light emitting region 108. In one embodiment, a
substantially uniform luminance or light flux output per area in
the light emitting region 108 is achieved despite the lower level
of light flux received by the light extraction features within the
compensation region 4901 of the light emitting region by, for
example, increasing the light extraction efficiency or area ratio
of the light extraction features to the area without light
extraction features within one or more regions of the compensation
region, increasing the width of the light mixing region between the
coupling lightguides and the light emitting region, decreasing the
light extraction efficiency or the average area ratio of the light
extraction features to the areas without light extraction features
in one or more regions of the light emitting region outside the
compensation region, and any suitable combination thereof.
[0599] FIG. 50 is a perspective top view of one embodiment of a
light emitting device 5000 comprising the film-based lightguide
4900 shown in FIG. 49 and a light source 102. In this embodiment,
tapered coupling lightguides 4902 are folded in the y direction
toward the light source 102 such that the light input edges 204 of
the coupling lightguides 4902 are disposed to receive light from
the light source 102. Light from the light source 102 propagating
through the tapered coupling lightguides 4902 exits the tapered
coupling lightguides 4902 and enters into the light emitting region
108 generally propagating in the +x direction while expanding in
the +y and -y directions, in the embodiment shown in FIG. 50, the
light source 102 is disposed within the region that did not
comprise a tapered coupling lightguide 4902 and the light source
102 does not extend in the y direction past a lower edge 4903 of
the light emitting device 5000. By not extending past the lower
edge 4903, the light emitting device 5000 has a shorter overall
width in the y direction. Furthermore, the light emitting device
5000 can maintain the shorter dimension, d1, in the y direction
(shown in FIG. 49) when the tapered coupling lightguides 4902 and
the light source 102 are folded under (-z direction and then +x
direction) the light emitting region 108 along the fold (or bend)
line 5001.
[0600] FIG. 51 is a perspective view of an embodiment light
emitting device 5100 comprising the light emitting device 5000
shown in FIG. 50 with the tapered coupling lightguides 4902 and
light source 102 shown in FIG. 50 folded (-z direction and then +x
direction) behind the light emitting region 108 along the fold (or
bend) line 5001. As can be seen from FIG. 51, a distance between
the lower edge of the light emitting region 108 and the
corresponding edge of the light emitting device 4903 in the -y
direction is relatively small. When this distance is small, the
light emitting region 108 can appear borderless, and for example, a
display comprising a backlight where the light emitting region 108
extends very close to the edge of the backlight can appear
frameless or borderless.
[0601] FIG. 52 is a top view of one embodiment of a film-based
lightguide 5201) comprising an array of angled, tapered coupling
lightguides 5201 formed by cutting regions in a lightguide 107 at a
first coupling lightguide orientation angle, .gamma., defined as
the angle between the coupling lightguide axis 5202 and the
direction 5203 parallel to the major component of the direction of
the coupling lightguides 5201 to the light emitting region 108 of
the lightguide 107. By cutting the tapered coupling lightguides
5201 within the lightguide 107 at a first coupling lightguide
orientation angle, the angled, tapered lightguides 5201, when
folded, provide volume with a dimension of sufficient length to
place a light source such that the light source does not extend
past the lower edge 4903 of the film-based lightguide 5200.
[0602] FIG. 53 is a perspective view of one embodiment of a light
emitting device 5300 comprising the film-based lightguide 5200
shown in FIG. 52 and a light source 102. As shown in FIG. 53, the
angled, tapered coupling lightguides 5201 are folded in the -y
direction toward the light source 102 such that the light input
surfaces 204 of the stacked coupling lightguides 5201 are disposed
to receive light from the light source 102.
[0603] FIG. 54 is a top view of one embodiment of a film-based
lightguide 5400 comprising a first array of angled, tapered
coupling lightguides 5201 formed by cutting regions in the
lightguide 107 at a first coupling lightguide orientation angle
5406 and a second array of angled, tapered coupling lightguides
5402 formed by cutting regions in the lightguide 107 at a second
coupling lightguide orientation angle 5407. By cutting the first
array of coupling lightguides 5201 and the second array of coupling
lightguides 5402 within the lightguide 107 at the first coupling
lightguide orientation angle 5406 and the second coupling
lightguide orientation angle 5407, respectively, the angled,
tapered lightguides 5201 and 5402, when folded, provide volume with
a dimension of sufficient length to place one or more light sources
102 such that the one or more light sources 102 do not extend past
the lower edge 4903 of the lightguide 107.
[0604] FIG. 55 is a perspective top view of one embodiment of a
light emitting device 5500 comprising the film-based lightguide
5400 shown in FIG. 54 and a light source 102 emitting light in the
+y direction and -y direction (such as two LEDs disposed back to
back). The first array of coupling lightguides 5201 are folded in
the -y direction toward the light source 102 such that each light
input surface 204 is disposed to receive light from the light
source 102 and the second array of coupling lightguides 5402 are
folded in the +y direction toward the light source 102 such that
each light input surface 204 is disposed to receive light from the
light source 102. The first and second array of coupling
lightguides 5201 and 5402 are angled away from the center of the
light emitting region 108 to allow the light source 102 to be
disposed in the central region of the lightguide 107 (in the y
direction) such that the light source 102 does not extend past the
lower edge 4903 or upper edge 5401 of the lightguide 107. The light
source 102, the first array of coupling lightguides 5201, and the
second array of coupling lightguides 5402 may be folded under the
light emitting region 108 along the fold (or bend) axis 5001 such
that the light emitting device 5500 is substantially edgeless or
has light emitting regions extending very close to the edges of the
light emitting device in the x-y plane.
[0605] FIG. 56 is a top view of one embodiment of a light emitting
device 5600 comprising the lightguide 107, the coupling lightguides
104 and a mirror 5601 functioning as a light redirecting optical
element including a curved or arcuate reflective surface or region
disposed to redirect light from the light source 102 into the
coupling lightguides 104. Within the coupling lightguides 104, the
light propagates through the coupling lightguides 104 into the
lightguide 107 and exits the lightguide 107 in the light emitting
region 108.
[0606] FIG. 57 is a top view of one embodiment of a light emitting
device 5700 comprising the lightguide 107, the coupling lightguides
104 and a mirror 5701. In this embodiment, mirror 5701 includes two
or more curved or arcuate surfaces or regions disposed to redirect
light from one or more light sources, such as the two light sources
102 shown in FIG. 57, into the coupling lightguides 104 where the
mirror is functioning as a bidirectional light turning optical
element. Within the coupling lightguides 104, the light propagates
through the coupling lightguides 104 into the lightguide 107 and
exits the lightguide 107 in the light emitting region 108. As shown
in FIG. 57, the light sources 102 are disposed to emit light with a
corresponding light source optical axis 5702 substantially oriented
parallel to the +x direction. The curved mirror redirects the light
into axis 5703 oriented in the +y and 5704 oriented in the -y
direction. In another embodiment, the optical axes of the light
sources 102 are oriented substantially in the -z direction (into
the page) and the curved mirror redirects the light into axes 5703
and 5704 oriented in the +y and -y directions, respectively.
[0607] FIG. 58 is a top view of one embodiment of a light emitting
device 5800 comprising the lightguide 107 and coupling lightguides
104 on opposite sides of the lightguide 107 that have been folded
behind the light emitting region 108 of the light emitting device
5800 along the lateral sides 5001 (shown by phantom lines in FIG.
58) such that the frames or border regions (5830, 5831) between the
light emitting region 108 and the corresponding edge (5001, 5832)
of the light emitting device 5800 in the +x direction, -x
direction, and +y direction are minimized and the light emitting
device 5800 can be substantially edgeless (or have a small frame)
along any desirable number of sides or edges, such as three sides
or edges as shown in FIG. 58.
[0608] FIG. 59 is a top view of one embodiment of a light emitting
device 5900 comprising the lightguide 107, with the coupling
lightguides 104 on two orthogonal sides. In this embodiment, a
light coupling optical element 5901 is disposed to increase the
light flux that couples from the light source 102 into the two sets
of coupling lightguides 104. A first portion of the light 5902 from
the light source 102 will refract upon entering the light coupling
optical element 5901 and be directed into a waveguide condition
within the coupling lightguides 104 oriented substantially parallel
to the x axis and a second portion of the light 5903 will refract
upon entering the light coupling optical element 5901 and be
directed into a waveguide condition within the coupling lightguides
104 oriented substantially parallel to the y axis.
[0609] FIG. 60 is a cross-sectional side view of a portion of one
embodiment of a light emitting device 6000 comprising the
lightguide 107 and the light input coupler 101. In this embodiment,
a low contact area cover 6001 is operatively coupled, such as
physically coupled as shown in FIG. 60, to the light input coupler
101 (or one or more elements within the light input coupler 101)
and wraps around the light input coupler 101 and is physically
coupled or maintained in a region near the lightguide 107 by a
suitable fastening mechanism, such as one or more fibers 6002 that
stitches the low contact area cover 6001 in contact or in proximity
to the lightguide 107. In the embodiment shown in FIG. 60, the
stitches pass through the low contact area cover 6001 and the
lightguide 107 and provide a very small surface area in the primary
direction (-x direction) of propagation of the light within the
light emitting portion of the lightguide 107. A physical coupling
mechanism with a small surface within the lightguide reduces the
scattering or reflection of light propagating within the lightguide
which can reduce optical efficiency or cause stray light, in the
embodiment shown in FIG. 60, the fiber (or wire, thread, etc.) 6002
provides a low contact area physical coupling mechanism that has a
small percentage of cross sectional area in the y-z plane
(orthogonal to the optical axis direction (-x direction) of the
light within the lightguide region).
[0610] FIG. 61 shows an enlarged view of a region of the lightguide
107 shown in FIG. 60 in which the lightguide 107 is in contact with
the low contact area cover 6001. In this embodiment, the low
contact area cover 6001 has convex surface features 6101 that
reduce the contact area 6102 in contact with the surface 6103 of
the lightguide 107 disposed near the low contact area cover 6101.
In other embodiments, the low contact area cover 6001 includes any
suitable feature that reduces the contact area 6102.
[0611] FIG. 62 is a side view of a portion of one embodiment of a
light emitting device 6200 comprising the lightguide 107 and
coupling lightguides 104 protected by a low contact area cover
6001. The low contact area cover 6001 is operatively coupled, such
as physically coupled as shown in FIG. 62, by a suitable fastening
mechanism, such as one or more sewn fibers 6002, to the lightguide
1007 at two or more regions of the low contact area cover 6001 such
that the low contact area cover wraps around the coupling
lightguides 104. A non-adjustable cylindrical tension rod 6205 and
an adjustable cylindrical tension rod 6201 are disposed
substantially parallel to each other in the y direction and are
operatively coupled, such as physically coupled by two braces 6202
that are substantially parallel to each other in the x direction.
The inner surface 6101 of the low contact area cover 6001 comprises
convex surface features. When the cylindrical tension rod 6201 is
translated in the +x direction, the inner surface 6101 of the low
contact area cover 6001 is pulled inward in the +z and -z
directions onto the lightguide 107 and coupling lightguide 104. The
surface relief features on the low contact area cover 6001 reduce
the amount of light lost from within the coupling lightguide 104
and/or the lightguide 107 when the cylindrical tension rod 6201 is
translated in the +x direction. Translating the tension rod in the
+x direction also reduces a height of the light emitting device
6200 parallel to the z direction by moving the coupling lightguides
104 closer together and closer to the lightguide 107. The low
contact area cover 6001 also provides protection from dust
contamination and physical contact by other components coupling
light out of the coupling lightguides 104 and/or the lightguide
film 107.
[0612] FIG. 63 is a perspective view of a portion of one embodiment
of a film-based lightguide 6300 comprising coupling lightguides
6301 including one or more flanges. In this embodiment, each
coupling lightguide 6301 includes a flange 6306 on each opposing
side of an end region 6307 of the coupling lightguides 6301 as
shown in FIG. 63. A strap 6302 is guided through two slits 6303
formed in a base 6304 and pulled by both ends in the y directions
(or in the +y direction, for example, if the region of the strap in
the -y direction is held fixed relative to the base 6304). By
tightening the strap 6302, the coupling lightguides 6301 are urged
closer together and toward the base 6304 in the z direction to
facilitate securing the coupling lightguides 6301 with respect to
the base 6304. Also, the strap 6303 and the hook regions formed by
the flanges 6306 prevent or limit the coupling lightguides 6301
from translating in the -x direction. In one embodiment, after the
coupling lightguides 6301 are urged together, the end region 6307
of the coupling lightguides 6301 and/or the flanges 6306 are cut or
otherwise removed along a cut axis 6305. The resulting new edge at
the end of the coupling lightguides 6301 along the cut axis 6305
can be an input surface or otherwise coupled to an optical element
or polished to form a new input surface for the coupling
lightguides 6301. The ends may be physically or optically coupled
to a window or an adhesive or epoxy such as an Ultraviolet (UV)
curable epoxy disposed between the ends of the coupling lightguide
6301 and a high gloss fluorinated ethylene propylene (FEP) film or
polished glass such that the film or glass can be removed, leaving
a glossy, polished input surface made of the epoxy which also helps
holds the ends of the coupling lightguides 6301 together. In
another embodiment, the holding mechanism is removed after one or
more of the coupling lightguides 6301 are adhered together or to
another component of the light emitting device 6300. In another
embodiment, the end region 6307 is not removed from the coupling
lightguides 6301 and the ends of the coupling lightguides 6301 form
the light input surface 204 as shown in FIG. 63.
[0613] FIG. 64 is a perspective view of one embodiment of a
film-based lightguide 6400 comprising a light input coupler and
lightguide 107 comprising a relative position maintaining element
3301 disposed proximal to a linear fold line or region. In this
embodiment, the relative position maintaining element 3301 has a
cross-sectional guide edge in a plane (x-y plane as shown) parallel
to the lightguide 107 that comprises a substantially linear angled
guide edge 3303 oriented at an angle 3302 about 45 degrees to the
direction 6404 (+y direction) parallel to the linear fold direction
(the -y direction). If the coupling lightguide 6401 is folded
without the relative position maintaining element 3301, the stress
point for the force of the fold or bend pulling the coupling
lightguide in the y direction is at the region 6402 near where the
coupling lightguide 6401 separates from the lightguide 107. By
using the relative position maintaining element 3301, when the
coupling lightguide 6401 is pulled in the -y direction, the force
is distributed across a length region 6403 of the angled guide edge
3303 of the relative position maintaining element 3301. In one
embodiment, the angled guide edges 3303 on the relative position
maintaining element 3301 reduce the likelihood of tearing the
coupling lightguide 6401 and enable a lower profile (reduced height
in the z direction) because the coupling lightguide 6401 can be
pulled with relatively more force. In another embodiment, the
thickness and edge profile of the relative position maintaining
element 3301 dictates a minimum bend radius for the fold in the
coupling lightguide 6401 near the length region 6403.
[0614] FIG. 65 is a perspective view of one embodiment of a
relative position maintaining element 6501 comprising rounded
angled edge surfaces 6502. By rounding the edge surfaces 6502, the
surface area of contact with a folded film is increased to the
rounded angled edge surface 6502. By spreading the force of pull in
the -y direction over a larger area of the coupling lightguide
6401, for example, the coupling lightguide 6401 is less likely to
fracture or tear.
[0615] FIG. 66 is a perspective view of one embodiment of a
relative position maintaining element 6600 comprising rounded
angled edge surfaces 6502 and rounded tips 6601. By rounding the
edge surfaces 6502, the surface area of contact with a folded film
is increased to the rounded angled edge surface 6502. By spreading
the force of pull in the -y direction over a larger area of the
coupling lightguide 6401, for example, the coupling lightguide 6401
is less likely to fracture or tear. By rounding the tips 6601 of
the relative position maintaining element 6600, the edge is less
sharp and less likely to induce a localized stress region in the
coupling lightguide 6401 as the coupling lightguide 6401 is folded
(or bent) or while maintaining the fold or bend.
[0616] FIG. 67 is a perspective view of a portion of one embodiment
of a film-based lightguide 6700 comprising coupling lightguides
6301 including one or more flanges 6306. In this embodiment, each
coupling lightguide 6301 includes a flange 6306 on each opposing
side of an end region 6307 of the coupling lightguides 6301 as
shown in FIG. 63. A strap 6302 is guided through two slits 6303 in
a base 6304 and pulled by both ends in the y directions (or in the
+y direction, for example, if the region of the strap in the -y
direction is held fixed relative to the base 6304). By tightening
the strap 6303, the coupling lightguides 6301 are urged closer
together and toward the base 6304 in the z direction to facilitate
securing the coupling lightguides 6301 with respect to the base
6304. Also, the strap 6303 and the hook regions formed by the
flanges 6306 prevent or limit the coupling lightguides 6301 from
translating in the -x direction. In one embodiment, after the
coupling lightguides 6301 are urged together, the end region 6307
of the coupling lightguides 6301 and/or the flanges 6306 are cut or
otherwise removed along an aperture cut 6701 by tearing or cutting
the regions between the aperture cut 6701 and the flanges 6306
along a cut axis 6305. An edge 6702 of the aperture cut 6701 then
becomes the light input surface of the coupling lightguides 6301.
For example, in one embodiment, the cutting device used to cut the
coupling lightguides 6301 from a film can also cut the light input
surface on the coupling lightguides and the flanges 6306 and strap
6302 assist with assembly.
[0617] FIG. 68 is a perspective view of a portion of one embodiment
of the light emitting device 6200 illustrated in FIG. 62 comprising
the lightguide 107 and light input coupler protected by a low
contact area cover 6001. In this embodiment, the low contact area
cover 6001 is physically coupled by a fiber 6002 to the lightguide
1007 in two regions of the low contact area cover 6001 by passing a
fiber 6002 through the two layers of the low contact area cover
6001 and the lightguide 107 in a sewing or threading type
action.
[0618] FIG. 69 is a top view of one embodiment of a light emitting
device 6900 with two light input couplers comprising coupling
lightguides 104 and a first light source 6902 and a second light
source 6903 disposed on opposite sides of the lightguide 107. An
aluminum bar type thermal transfer element 6901 is disposed to
thermally couple heat from the first light source 6902 and the
second light source 6903 and dissipate heat along the length of
light emitting device 6900 in the x direction, in other
embodiments, one or more suitable thermal transfer elements may be
incorporated into the light emitting device 6900 to facilitate
dissipating heat from the light emitting device 6900.
[0619] FIG. 70 is a perspective view of one embodiment of a light
emitting device 7000 comprising the lightguide 107, the light input
coupler 101, and a light reflecting film 7004 disposed between the
light input coupler 101 and the light emitting region 108. A
circuit board 7001 for the light source in the light input coupler
101 couples heat from the light source to a thermal transfer
element heat sink 7002 thermally coupled to the circuit board 7001.
In this embodiment, the thermal transfer element 7002 comprises
fins 7003 and is extended in the x-y plane behind the light
reflecting film 7004 and the light emitting region 108 to provide
an increased surface area and occupy a volume that does not extend
past the edges 7030 of the lightguide 107 to conduct heat away from
the circuit board 7001 and the light source in the light input
coupler 101.
[0620] FIG. 71 is a top view of a region of one embodiment of a
light emitting device 7100 comprising a stack 7101 of coupling
lightguides disposed to receive light from a light collimating
optical element 7102 and the light source 102. The output surface
7103 of the light collimating optical element 7102 corresponds in
shape to the light input surface 7105 of the stack 7101 of coupling
lightguides. Light 7104 from the light source 102 is collimated by
the light collimating optical element 7102 and enters the stack
7101 of coupling lightguides. For example, as shown in FIG. 71, the
output surface 7103 has a rectangular shape substantially matching
the rectangular shape of the light input surface 7105 of the stack
7101 of coupling lightguides.
[0621] FIG. 72 is a cross-sectional side view of the light emitting
device 7100 shown in FIG. 71. The light 7104 collimated by the
light collimating optical element 7102 enters the stack 7101 of
coupling lightguides 7201.
[0622] FIG. 73 is a top view of one embodiment of a light emitting
device 7300 comprising the stack 7101 of coupling lightguides
physically coupled to the light collimating optical element 7102.
The physical coupling region of the stack 7101 of coupling
lightguides defines a cavity 7331 within which the light
collimating optical element physical coupling region 7302 is
disposed. In the embodiment shown, the light collimating optical
element physical coupling region 7302 is a ridge 7330 on the light
collimating optical element 7102 and the physical coupling region
of the stack 7101 of coupling lightguides is the region 7301
partially surrounding an opening or aperture cut within each
coupling lightguide which, when stacked, forms a cavity 7331 that
substantially constrains and aligns the light collimating element
7102 in the x and y directions.
[0623] FIG. 74 is a top view of a region of one embodiment of a
light emitting device 7400 comprising a light turning optical
element 7401 optically coupled using an index matching adhesive
7402 to a stack 7101 of coupling lightguides. Light 7403 from the
light source 102 totally internally reflects off of the light
turning surface 7405 of the light turning optical element 7401,
passes through the index matching adhesive 7402 and into the stack
7101 of coupling lightguides and the optical axis of the light 7403
from the light source 102 is rotated. Light 7404 from the light
source 102 passes directly into the stack 7101 of coupling
lightguides without reflecting off of the light turning surface
7405 of the light turning optical element 7401.
[0624] FIG. 75a is a top view of a region of one embodiment of a
light emitting device 7500 comprising the light source 102 disposed
adjacent a lateral edge 7503 of a stack 7501 of coupling
lightguides with light turning optical edges 7502. The light
turning optical edges 7502 reflect a portion of the incident light
from the light source 102 with an optical axis 7504 in a first
direction (-y direction, for example) such that the optical axis
7504 is rotated from the first direction by an angle 7506 to an
optical axis 7505 in a second direction (-x direction, for
example).
[0625] FIG. 75b is a top view of a region of one embodiment of a
light emitting device 7530 comprising the light source 102 disposed
adjacent the light input surface edge 7507 of the extended region
7508 of the stack 7501 of coupling lightguides with light turning
optical edges 7502. In this embodiment, the extended region 7508
allows the light input surface edge 7507 to be cut, trimmed, and/or
polished (separately or as a collection of coupling lightguides in
a stack) or bonded to a light collimating optical element without
damaging (scratching or tearing, for example) or unnecessarily
coupling light out of the lateral edges 7503 of the stack 7501 of
coupling lightguides (with overflow adhesive, for example).
[0626] FIG. 76 is a top view of a region of one embodiment of a
light emitting device 7600 comprising the light source 102 disposed
to couple light into two light turning optical elements 7401
optically coupled using an adhesive 7402 (such as an index matching
adhesive or optical adhesive for example) to two stacks 7101 of
coupling lightguides.
[0627] FIG. 77 is a top view of a region of one embodiment of a
light emitting device 7700 comprising the light source 102 disposed
to couple light into a bi-directional light turning optical element
7701 optically coupled using index matching adhesive 7402 to two
stacks 7101 of coupling lightguides. In this embodiment, a single
bi-directional light turning optical element 7701 divides and
rotates the optical axis of light from a single light source in a
first direction (-y direction) into two different directions (-x
and +x directions), replaces two unidirectional light turning
optical elements, and reduces part count and associated costs.
[0628] FIG. 78 is a top view of a region of one embodiment of a
light emitting device 7800 comprising two light sources 102
disposed to couple light into a bi-directional light turning
optical element 7801 optically coupled using index matching
adhesive 7402 to two stacks 7101 of coupling lightguides. In this
embodiment, a single bi-directional light turning optical element
7701 is designed to divide and rotate the optical axes of light
from two light sources from a first direction (-y direction) to two
different directions (+x and -x directions).
[0629] FIG. 79 is a top view of a region of one embodiment of a
light emitting device 7900 comprising the light source 102 disposed
to couple light into two stacks 7501 of coupling lightguides with
light turning optical edges 7502. In this embodiment, the two
stacks 7501 of coupling lightguides divide and rotate the optical
axis of light from the light source from a first direction (-y
direction) to two different directions (+x and -x directions).
[0630] FIG. 80 is a top view of a region of one embodiment of a
light emitting device 8000 comprising the light source 102 disposed
to couple light into two overlapping stacks 7501 of coupling
lightguides with light turning optical edges 7502. In this
embodiment, the two stacks 7501 of coupling lightguides divide and
rotate the optical axis of light from the light source from a first
direction (-y direction) to two different directions (+x and -x
directions).
[0631] FIG. 81 is a top view of a region of one embodiment of a
light emitting device 8100 comprising the light source 102 disposed
to couple light into the stack 7501 of coupling lightguides with
light turning optical edges 7502. In this embodiment, the stack
7501 of coupling lightguides has tabs 8102 with tab alignment
openings or apertures 8101. The tab alignment openings or apertures
8101 may be used, for example, to register the stack 7501 of
coupling lightguides (and their light input surface) with a pin
extending from a circuit board comprising a light source to enable
efficient light coupling into the stack 7501 of coupling
lightguides.
[0632] FIG. 82 is a top view of a region of one embodiment of a
light emitting device 8200 comprising the light source 102 disposed
to couple light into the stack 7501 of coupling lightguides with
light turning optical edges 7502. In this embodiment, the stack
7501 of coupling lightguide has alignment openings or apertures
8201 in low light flux density regions 8202. The alignment openings
or apertures 8201 may be used, for example, to register the stack
7501 of coupling lightguides to the light source 102 and they are
located in a low light flux density region 8202 such that a tab is
not needed and any light loss due to the location of the alignment
openings or apertures 8201 within the stack 7501 of coupling
lightguides is minimized.
[0633] FIG. 83 is a top view of a region of one embodiment of a
light emitting device 8300 comprising the light source 102 disposed
to couple light into the stack 7501 of coupling lightguides with a
light source overlay tab region 8301 comprising an alignment cavity
8302 for registration of the light input surface 8303 of the stack
7501 of coupling lightguides with the light source 102. In this
embodiment, for example, the alignment cavity 7501 within the stack
7501 of coupling lightguides may be placed over the light source
102 such that a light input surface 8303 of the stack 7501 of
coupling lightguides is substantially registered and aligned in the
x and y directions with the light source 102.
[0634] FIG. 84 is a top view of one embodiment of a lightguide 8400
comprising the film-based lightguide 107 having coupling
lightguides 8401 with light turning optical edges 7502. The
coupling lightguides 8401 can be folded in the +z direction and
translated laterally in the +x direction 8402 (shown folded in FIG.
85) such that the coupling lightguides 8401 stack and align above
one another.
[0635] FIG. 85 is a top view of one embodiment of a light emitting
device 8500 comprising the lightguide 8400 shown in FIG. 84 with
the coupling lightguides 8401 folded and translated to form the
stack 7501 of coupling lightguides 8401 such that the stack 7501
extends past a lateral edge 8501 of the lightguide region 106 of
the film-based lightguide 107. Light 8502 from the light source 102
has an optical axis in the -y direction that is rotated by the
light turning optical edges 7502 of the stack 7501 of coupling
lightguides to the -x direction and the fold in the stack 7501 of
coupling lightguides 8401 redirects the coupling lightguide
orientation to the -y direction such that the light has an optical
axis exiting the coupling lightguides in the -y direction. The
light 8502 then propagates into the lightguide region 106 of the
film-based lightguide 107 and exits the film-based lightguide 107
in the light emitting region 108.
[0636] FIG. 86 is a top view of one embodiment of a lightguide 8600
comprising the film-based lightguide 107 having coupling
lightguides 8401 with light turning optical edges 7502 and a
non-folded coupling lightguide 8603. The non-folded coupling
lightguide 8603 has a width 8601 along the edge of the lightguide
region 106 from which the coupling lightguides 8401 extend and a
length 8602 in the direction perpendicular to the edge where the
coupling lightguides 8401 connect with the lightguide region
106.
[0637] FIG. 87 is a top view of one embodiment of a light emitting
device 8700 comprising the lightguide 8600 shown in FIG. 86 with
the coupling lightguides 8401 folded and translated to form the
stack 7501 of coupling lightguides 8401 that do not extend past the
lateral edge 8501 (or a plane comprising the lateral edge 8501) of
the lightguide region 106 of the film-based lightguide 107. Light
8502 from the light source 102 has an optical axis in the -y
direction that is rotated by the light turning optical edges 7502
of the stack 7501 of coupling lightguides 8401 to the -x direction,
and the fold in the stack 7501 of coupling lightguides 8401
redirects the coupling lightguide orientation to the -y direction
such that the light has an optical axis exiting the coupling
lightguides 8401 in the -y direction. The light 8502 then
propagates into the lightguide region 106 and exits the film-based
lightguide 107 in the light emitting region 108. Light 8702 from
the light source 102 has an optical axis in the -y direction and
passes through the non-folded coupling lightguide 8603 and into the
lightguide region 106 directly. In this embodiment, the non-folded
coupling lightguide 8603 permits the stack 7501 of coupling
lightguides 8401 to not extend past the lateral edge 8501 of the
lightguide region 106 of the film-based lightguide 107 because the
non-folded coupling lightguide 8603 does not need to be folded and
translated in the +x direction to receive light from the light
source 102.
[0638] FIG. 88 is a top view of one embodiment of a lightguide 8800
comprising the film-based lightguide 107 having coupling
lightguides 8801 with light turning optical edges 8803 and light
collimating optical edges 8802. The coupling lightguides 8801 can
be folded in the /z direction and translated laterally in the +x
direction 8402 (shown folded in FIG. 89) such that the coupling
lightguides 8801 stack and align above one another.
[0639] FIG. 89 is a top view of one embodiment of a light emitting
device 8900 comprising the lightguide 8800 shown in FIG. 88 with
the coupling lightguides 8801 folded and translated to form a stack
8902 of coupling lightguides 8801 such that the stack 8902 of
coupling light guides 8801 extends past a lateral edge 8501 of the
lightguide region 106 of the film-based lightguide 107. Light 8901
from the light source 102 is collimated by the light collimating
optical edges 8802 and has an optical axis in the -y direction that
is rotated by the light turning optical edges 8803 of the stack
8902 of coupling lightguides 8801 to the -x direction and the fold
in the stack 8902 of coupling lightguides 8801 redirects the
coupling lightguide orientation to the -y direction such that the
light has an optical axis exiting the coupling lightguides 8801 in
the -y direction. The light 8901 then propagates into the
lightguide region 106 of the film-based lightguide 107 and exits
the film-based lightguide 107 in the light emitting region 108.
[0640] FIG. 90 is a top view of one embodiment of a lightguide 9000
comprising the film-based lightguide 107 with coupling lightguides
9001 with light turning optical edges 8803, light collimating
optical edges 8802, and extended regions 7508. The coupling
lightguides 9001 can be folded in the +z direction and translated
laterally in the +x direction 8402 (shown folded in FIG. 91) such
that the coupling lightguides 9001 stack and align above one
another.
[0641] FIG. 91 is a top view of one embodiment of the lightguide
9000 shown in FIG. 90 with the coupling lightguides 9001 folded and
translated to form a stack 9101 of coupling lightguides 9001 such
that the stack 9101 of coupling lightguides 9001 extends past a
lateral edge 8501 of the lightguide region 106 of the film-based
lightguide 107. The extended regions 7508 of the stack 9101 of the
coupling lightguides 9001 extend past the lateral edges 7503 of the
coupling lightguides 9001 and the stack 9101 can be cut and/or
polished along a cut line 9102 (or adhered to an optical element or
light source) without damaging the lateral edge 7503.
[0642] FIG. 92 is a top view of one embodiment of a lightguide
9201) comprising the film-based lightguide 107 with a first set of
coupling lightguides 8401 and a second set of coupling lightguides
9203 with light turning optical edges 9230 oriented to turn light
in a plurality of directions, and a non-folded coupling lightguide
9201. The coupling lightguides 8401 can be folded in the +z
direction and translated laterally in the +x direction 8402 (shown
folded in FIG. 93) such that they stack and align above one
another. The coupling lightguides 9203 can be folded in the +z
direction and translated laterally in the -x direction 9202 (shown
folded in FIG. 93) such that they stack and align above one
another.
[0643] FIG. 93 is a perspective top view of one embodiment of a
light emitting device 9300 comprising the light source 102 disposed
to couple light into the lightguide 9200 shown in FIG. 92 with the
first set of coupling lightguides 8401 folded and translated in the
+x direction and the second set of coupling lightguides 9203 folded
and translated in the -x direction. In this embodiment, the first
set of coupling lightguides 8401 are folded and translated above
the second set of coupling lightguides 9203 which are folded and
translated above the non-folded coupling lightguide 9201 disposed
to receive light from the light source 102 and transmit light to
the lightguide region 106.
[0644] FIG. 94 is a top view of one embodiment of a light emitting
device 9400 comprising the light source 102 disposed to couple
light into the lightguide 9200 shown in FIG. 92 with the first set
of coupling lightguides 8401 folded and translated in the +x
direction and the second set of coupling lightguides 9203 folded
and translated in the -x direction. In this embodiment, the first
set of coupling lightguides 8401 are folded and translated such
that the first set of coupling lightguides 8401 are interleaved
with the folded and translated second set of coupling lightguides
9203 above the non-folded coupling lightguide 9201. In one
embodiment, interleaving the coupling lightguides 8401 and 9203
near the light source 102 improves the uniformity of the light
within the lightguide region 106 to facilitate preventing or
limiting undesirable variations in light source alignment and/or
light output profile.
[0645] FIG. 95 is a top view of one embodiment of a lightguide 9500
comprising the film-based lightguide 107 comprising coupling
lightguides 8401 having light turning optical edges 7502 with the
coupling lightguides extended in shapes inverted along a first
direction 9501.
[0646] FIG. 96 is a perspective view of one embodiment of folded
lightguides 9600 comprising the lightguide 9500 shown in FIG. 95.
The coupling lightguides 8401 are folded 9602 by translating one
end (the top end shown in FIG. 95) in the +z direction, -x, and -y,
then the -z direction using two relative position maintaining
elements 2901 to form a stack 7501 of coupling lightguides 8401. In
a further embodiment, the stack 7501 of coupling lightguides 8401
may be cut along cut lines 9601 to form two stacks 7501 of coupling
lightguides 8401.
[0647] FIG. 97 is a top view of one embodiment of a lightguide 9700
comprising the film-based lightguide 107 having coupling
lightguides 9702 with light turning optical edges 8803, light
collimating optical edges 8802, and light source overlay tab
regions 8301 comprising alignment cavities 8302 for registration of
the light input surface of the stack of coupling lightguides with a
light source. The lightguide 9700 also comprises a non-folding
coupling lightguide 9703 with a collimating optical edge 8802, and
a light source overlay tab region 8301 comprising an alignment
cavity 8302 for registration of the light input surface of the
non-folded coupling lightguide 9703 with a light source. The
coupling lightguides 9702 further comprise curved regions 9701 on
the edge of the coupling lightguides 9702 to reduce the likelihood
of stress (such as resulting from torsional or lateral bending, for
example) focusing at a sharp corner, thus reducing the likelihood
of film fracture. The coupling lightguides 9702 can be folded in
the +z direction and translated laterally in the +x direction 8402
(shown folded in FIG. 98) such that they stack and align above one
another.
[0648] FIG. 98 is a top view of one embodiment of a light emitting
device 9800 comprising the light source 102 (shown in FIG. 99) and
the lightguide 9700 shown in FIG. 97 with the coupling lightguides
9702 folded and translated to form a stack 9803 of coupling
lightguides 9702 aligned along one edge of the lightguide region
106. Light 9802 from the light source 102 is collimated by the
light collimating optical edges 8802 and has an optical axis in the
-y direction that is rotated by the light turning optical edges
8803 of the stack 9803 of coupling lightguides 9702 to the -x
direction and the fold in the stack 9803 of coupling lightguides
9702 redirects the coupling lightguide orientation to the -y
direction such that the light has an optical axis exiting the
coupling lightguides 9702 in the -y direction. The light 9802 then
propagates into the lightguide region 106 of the film-based
lightguide 107. Light 8702 from the light source 102 has an optical
axis in the -y direction and passes through the non-folded coupling
lightguide 9703 and into the film-based lightguide 107
directly.
[0649] FIG. 99 is an enlarged side view near the light source 102
in the y-z plane of the light emitting device 9800 illustrated in
FIG. 98. An alignment guide 9903 comprises an alignment arm 9801
that is a cantilever spring with a curved front edge disposed above
the light source 102. The alignment arm 9801 applies a force
against the stack 9803 of coupling lightguides 9702 to maintain the
position of the light input surfaces 103 of the coupling
lightguides 9702 near the light output surface 9901 of the light
source 102. In this embodiment, the alignment arm 9801 is inserted
through the alignment cavities 8302 and the coupling lightguides
9702 can be pulled in the +y direction and downward (-z direction)
such that the alignment cavities 8302 are positioned over the
opposite end of the alignment guide 9803 and the light source 102
(the free end of the alignment arm 9801 can be lifted slightly
during this movement if necessary). In this embodiment, the
alignment cavities 8302 register and substantially maintain the
position of the light input surfaces 103 of the coupling
lightguides 9702 relative to the light output surface 9901 of the
light source 102 in the x and y directions and the alignment arm
9801 on the alignment guide 9903 maintains the relative position in
the z direction by applying force in the -z direction to position
the stack 9803 of coupling lightguides 9702 against each other and
the light source base 9902 (which could be a circuit board, for
example). Light 9904 from the light source 102 exits the light
output surface 9901 of the light source 102 and propagates into the
coupling lightguides 9702 through the light input surface 103.
[0650] FIG. 100 is an enlarged side view of a region near the light
source 102 in the y-z plane of one embodiment of a light emitting
device 10000 comprising an alignment guide 9903 with an alignment
arm 9801 that is a cantilever spring with a curved edge disposed
above a light source 102 and light collimating optical element
7102. The alignment arm 9801 applies a force against a stack of
coupling lightguides 9702 to maintain the position of the light
input surfaces 103 of the coupling lightguides 9702 near the light
output surface 10002 of the light collimating optical element 7102.
In this embodiment, the alignment arm 9801 is inserted through the
alignment cavities 8302 and the coupling lightguides 9702 can be
pulled in the +y direction. In this embodiment, the alignment
cavities are not sufficient in length to cover the alignment guide
9903, and the coupling lightguides 9702 remain held in place in the
z direction by the alignment arm 9801. In this embodiment, the
alignment cavities 8302 register and substantially maintain the
position of the light input surfaces 103 of the coupling
lightguides 9702 relative to the light output surface 10002 of the
light collimating optical element 7102 in the x and +y directions
and the alignment arm 9801 on the alignment guide 9903 maintains
the relative position in the z direction by applying force in the
-z direction to position the stack 9803 of coupling lightguides
9702 against each other and the light source base 9902 (which could
be a circuit board, for example). Friction with the stack of
coupling lightguides 9702 and the light source base 9902 and the
alignment arm 9801 due to the force from the alignment arm 9801 in
the -z direction and the friction from the fit of the inner walls
of the cavities 8302 and the light collimating optical element 7102
and/or the light source 102 help prevent the coupling lightguides
9702 from translating in the -y direction. In another embodiment,
the light input surface 103 of the coupling lightguides 9702 are
optically bonded to the light output surface 10002 of the light
collimating optical element 7401 (or they are optically bonded to
the light output surface of the light source 102 or a light turning
optical element). Light 10003 from the light source 102 exits the
light output surface 9901 of the light source 102 and propagates
into the light collimating optical element 7102 where the light is
collimated in the x-y plane and exits the light output surface
10002 of the light collimating optical element 7102 and enters the
light input surface 103 of the coupling lightguides 9702 where it
propagates to the lightguide region 106 (not shown).
[0651] FIG. 101 is a cross-sectional side view of a region of one
embodiment of a light emitting device 10100 comprising a stack 7501
of coupling lightguides with interior light directing edges 10101
disposed near the input edge of the stack 7501 of coupling
lightguides and interior light directing edges 10104 disposed near
the lightguide region 106 of the film-based lightguide 107. Light
10102 from the light source 102 enters the stack 7501 of coupling
lightguides and is reflected and redirected by the interior light
directing edges 10101 disposed near the input edge surface of the
stack 7501 of coupling lightguides. Light 10103 from the light
source 102 is reflected and redirected by the interior light
directing edge 10101 disposed near the input edge of the stack 7501
of coupling lightguides and further reflected and redirected by the
interior light directing edge 10104 disposed near the lightguide
region 106 of the film-based lightguide 107.
[0652] FIG. 102 is a cross-sectional side view of an embodiment of
a light emitting display 10200 comprising a reflective spatial
light modulator 10209 and a film-based lightguide 2102 frontlight
adhered to the flexible display connector 10206 of the reflective
spatial light modulator 10209 using an optical adhesive cladding
layer 801. The film-based lightguide 2102 further comprises an
upper cladding layer 10201 on the side opposite the reflective
spatial light modulator 10209. The flexible display connector 10206
carries the electrical connection between the display driver 10205
and the active layer 10203 of the reflective spatial light
modulator 10209 and is physically coupled to the bottom substrate
10204 of the reflective spatial light modulator 10209. Light 10207
from the side emitting LED light source 10208 physically coupled to
the flexible display connector 10206 is directed into the
film-based lightguide 2102 and is redirected by light extraction
features 1007 through the optical adhesive cladding layer 801, the
top substrate 10202 of the reflective spatial light modulator
10209, reflects within the active layer 10203, passes back through
the top substrate 10202, the optical adhesive cladding layer 801,
the film-based lightguide 2102, and the upper cladding layer 10201
and exits the light emitting display 10200.
[0653] FIG. 103 is a cross-sectional side view of one embodiment a
light emitting display 10300 with a film-based lightguide 10301
physically coupled to a flexible display connector 10206 and the
film-based lightguide 10301 is a top substrate for the reflective
spatial light modulator 10209. Light 10302 from the light source
102 physically coupled to the flexible display connector 10206 is
directed into the film-based lightguide 10301 and is redirected by
light extraction features to the active layer 10203 where the light
reflects and passes back through the film-based lightguide 10301,
and the upper cladding layer 10201 and exits the light emitting
display 10300.
[0654] FIG. 104 is a perspective view of one embodiment of a light
emitting device 10400 comprising a film-based lightguide 2102
physically coupled to the flexible connector 10206 for the
reflective spatial light modulator 10209 with a light source 102
disposed on a circuit board 10401 physically coupled to the
flexible connector 10206.
[0655] FIG. 105 is a perspective view of one embodiment of a light
emitting device 10500 comprising a film-based lightguide 2102
physically coupled to the flexible connector 10206 fir the
reflective spatial light modulator 10209 with a light source 102
disposed on the flexible connector 10206.
[0656] FIG. 106 is a perspective view of one embodiment of a light
emitting display 10600 comprising the light emitting device 10400
shown in FIG. 104 further comprising a flexible touchscreen 10601
disposed on the opposite side of the film-based lightguide 2102
than the reflective spatial light modulator 10209. In this
embodiment, the film-based lightguide 2102 extends from the light
emitting region 10603 of the light emitting display 10600 in the
direction and folds behind the light emitting region 10603. The
flexible touchscreen 10601 extends in the +y direction from the
light emitting region 10603 of the light emitting display 10600 and
folds behind the light emitting region 10603. The flexible
touchscreen 10601 further comprises touchscreen drivers 10602
disposed on the flexible touchscreen 10601.
[0657] FIG. 107 is a perspective view of one embodiment of a light
emitting display 10700 comprising the light emitting device 10400
shown m FIG. 104 further comprising a flexible touchscreen 10601
disposed between the film-based lightguide 2012 and the reflective
spatial light modulator 10209. In this embodiment, the film-based
lightguide 2102 extends from the light emitting region 10603 of the
light emitting display 10600 in the -x direction and folds behind
the light emitting region 10603. The flexible touchscreen 10601
extends in the -y direction from the light emitting region 10603 of
the light emitting display 10600 and folds behind the light
emitting region 10603. The flexible touchscreen 10601 further
comprises touchscreen drivers 10602 disposed on the flexible
touchscreen 10601.
[0658] FIG. 108 is a perspective view of one embodiment of a
reflective display 10800 comprising a flexible connector 10206
connecting the reflective spatial light modulator 10209 and the
display drivers 10205 on a circuit board 10401, and further
comprising a film-based lightguide frontlight comprising a
film-based lightguide 2102 with coupling lightguides 104 folded in
a linear fold region 2902 using a relative position maintaining
element 3301 with substantially linear sections 3303. The relative
position maintaining element 3301 extends past the light input
surface 103 of the coupling lightguides 104 in a direction (-y
direction) parallel to the optical axis of the light source (+y
direction). Registration pins 10804 physically coupled to the light
source circuit board 10805 (that is physically coupled to the light
source 102) pass through alignment openings or apertures in the
relative position maintaining element 3301 and tab alignment
openings or apertures 8101 in the coupling lightguides 104. In one
embodiment, the portion of the film-based lightguide 2102 disposed
near the reflective spatial light modulator 10209 and the
reflective spatial light modulator 10209 are translated and folded
10801 along the fold line 10802 in the +z and +x directions to form
a folded light emitting display. Once folded, the film-based
frontlight 2102 directs light in the direction toward the active
display area 10803 of the reflective spatial light modulator 10209
and the reflective spatial light modulator 10209 reflects a portion
of the light in the +z direction.
[0659] FIG. 109 is a perspective view of one embodiment of a
reflective display 10900 comprising a flexible connector 10206
connecting the reflective spatial light modulator 10209 and the
display drivers 10205 on a circuit board 10401, and further
comprising a film-based lightguide frontlight comprising a
film-based lightguide 2102 with coupling lightguides 104 folded in
a linear fold region 2902 using a relative position maintaining
element 3301 with substantially linear sections 3303. The relative
position maintaining element 3301 extends past the light input
surface 103 of the coupling lightguides 104 and the light source
102 in a direction (-y direction) parallel to the optical axis of
the light source (+y direction). Registration pins 10804 physically
coupled to the relative position maintaining element 3301 pass
through the tab alignment openings or apertures 8101 in the
coupling lightguides 104. The reflective display further comprises
a flexible touchscreen film 10501 laminated to the film-based
lightguide 2102. The touchscreen drivers 10502 and the light source
are disposed on the flexible touchscreen film 10501. In one
embodiment, the portion of the film-based lightguide 2102 and
flexible touchscreen film 10501 disposed near the reflective
spatial light modulator 10209 and the reflective spatial light
modulator 10209 are translated and folded 10801 along the fold line
10802 in the +z and +x directions to form a folded light emitting
display. The film-based frontlight 2102 directs light in the -z
direction and the reflective spatial light modulator 10209 reflects
a portion of the light in the +z direction.
[0660] FIG. 110 is a top view of one embodiment of a lightguide
11000 comprising the film-based lightguide 107 comprising an array
of coupling lightguides 104. Each coupling lightguide 104 of the
array of coupling lightguides further comprises a sub-array of
coupling lightguides 11001 with a smaller width than the
corresponding coupling lightguide 104 in the y direction.
[0661] FIG. 111 is a perspective top view of one embodiment of a
light emitting device 11100 comprising the lightguide 11000 shown
in FIG. 110. The coupling lightguides 104 are folded such that they
overlap and are aligned substantially parallel to the y direction,
and the sub-array of coupling lightguides 11001 are subsequently
folded such that they overlap and are aligned substantially
parallel to the x direction and disposed to receive light from the
light source 102. The sub-array of coupling lightguides 11001
couple the light into the coupling lightguides 104 that couple the
light into the film-based lightguide 107.
[0662] FIG. 112 is a cross-sectional side view of a region of one
embodiment of a light emitting device 11200 comprising a stacked
array of coupling lightguides 104 comprising core regions 601 and
cladding regions 602. The core regions 601 comprise vertical light
turning optical edges 11201. The cladding regions 602 in the inner
regions of the stack of coupling lightguides 104 do not extend to
the vertical light turning optical edges 11201 and the core regions
601 are not separated by a cladding layer in the region near the
light source 102. The light source 102 and a light collimating
optical element 11203 are disposed at a light input surface 11206
on the stacked array of coupling lightguides 104. Light 11207 from
the light source 11).sub.2 is collimated by the reflecting surface
11202 of the light collimating optical element 11203, enters the
stack of coupling lightguides 104 and an optical axis 12130 of
light 11207 is rotated toward the +x direction by the vertical
light turning optical edges 11201 of the core regions 601 of the
coupling lightguides. Light 11207 propagates in the core regions
601 near the light source 102 and totally internally reflects in a
core region when encountering an air gap 11208 or cladding layer
602. In one embodiment, the vertical light turning optical edges
11201 are formed by cutting the stack of core regions 601 at an
angle 11205 from a normal 11204 to the surface of the stack of
coupling lightguides 104. In another embodiment, the outer cladding
region 602 near the light source 102 does not extend to the region
between the light collimating optical element 11203 and the stack
of core regions 601 near the light collimating optical element
11203. In another embodiment, the cladding region 602 near the
light collimation element 11203 is a low refractive index optical
adhesive that bonds the light collimating optical element 11203 to
the stack of coupling lightguides 104.
[0663] FIG. 113 is a cross-sectional side view of a region of one
embodiment of a light emitting device 11300 comprising a stacked
array of coupling lightguides 104 comprising core regions 601 and
cladding regions 602. The core regions 601 comprise vertical light
turning optical edges 11201 and vertical light collimating optical
edges 11301. The cladding regions 602 in the inner regions of the
stack of coupling lightguides 104 do not extend to the vertical
light turning optical edges 11201 or the vertical light collimating
optical edges 11301 and the core regions 601 are not separated by a
cladding layer in the region near the light source 102. The light
source 102 is disposed at a light input surface 11206 on the stack
coupling lightguides 104. Light 11302 from the light source 102
enters the stack of coupling lightguides 104 and is collimated by
the vertical light collimating optical edges 11301 of the core
regions 601 of the coupling lightguides 104. The light 11302 is
rotated toward the +x direction by the vertical light turning
optical edges 11201 of the core regions 601 of the coupling
lightguides 104. Light 11302 propagates in the core regions 601
near the light source 102 and totally internally reflects in a core
region 601 when encountering an air gap 11208 or cladding region
602.
[0664] FIG. 114 is a cross-sectional side view of a region of one
embodiment of a light emitting device 11400 comprising a stacked
array of coupling lightguides 104 comprising core regions 601 and
cladding regions 602. The core regions 601 comprise vertical light
turning optical edges 11201 and vertical light collimating optical
edges 11301. The cladding regions 602 in the inner regions of the
stack of coupling lightguides 104 do not extend to the vertical
light turning optical edges 11201 or the vertical light collimating
optical edges 11301 and the core regions 601 are not separated by a
cladding layer in the region near the light source 102. A coupling
lightguide 104 near the vertical light collimating optical edges
11301 defines a cavity 11401. The light source 102 is disposed
within the cavity 11401 and light 11402 from the light source 102
enters the stack of coupling lightguides 104 and is collimated by
the vertical light collimating optical edges 11301 of the core
regions 601 of the coupling lightguides 104. The light 11402 is
rotated toward the +x direction by the vertical light turning
optical edges 11201 of the core regions 601 of the coupling
lightguides. Light 11402 propagates in the core regions 601 near
the light source and totally internally reflects in a core region
when encountering an air gap 11208 or cladding region 602. In this
embodiment, the cavity 11401 facilitates registration and increases
optical efficiency of the light emitting device 11400. The cavity
11401 can also serve as an alignment cavity to position the light
source 102 at a predetermined location (x, y, and +z registration)
relative to the vertical light collimating optical edges 11301
and/or the light turning optical edges 11201. By placing the light
source 102 within the cavity 11401 of the stacked array of coupling
lightguides 104, the light flux from the light source 102 directed
into the stacked array of coupling lightguides 104 and remaining in
the stacked array of coupling lightguides 104 in a total internal
reflection condition in areas with the cladding regions 602, or
near the lightguide region (not shown) further in the +x direction,
is increased relative to a light source disposed at the larger
outer surface. In another embodiment, the cavity 11401 extends
through two or more coupling lightguides 104 or core regions 601 of
the coupling lightguides 104.
[0665] FIG. 115 is a perspective view of a region of one embodiment
of a light emitting device 11500 comprising a stacked array of
coupling lightguides 104 disposed within an alignment cavity 11501
of a thermal transfer element 7002 that is operatively coupled,
such as physically coupled, to a base 9902 for a light source (not
shown in FIG. 36). The thermal transfer element 7002 comprises
extended fins 7003. Heat from the light source disposed within the
thermal transfer element 7002 is transferred away from the light
source by the thermal transfer element 7002. The light source is
disposed to couple light into the stack of coupling lightguides
104. The alignment cavity 11501 can register the stack of coupling
lightguides 104 in the y and z directions and the light source can
provide registration in the +x direction (the coupling lightguides
104 are prevented from translating past the light source in the +x
direction). Friction or other mechanical or adhesive means can
facilitate registration and/or maintaining the position of the
stacks relative to the light source 102 in the -x direction
(prevent the stack from pulling out of the cavity). In another
embodiment, an internal ridge or an end of the cavity 11501
prevents or limits the lateral movement of the coupling lightguides
104 in the +x direction and provides a predetermined minimum
distance between the light source 102 and the stack of coupling
lightguides 104 (which can reduce the maximum operating temperature
at the ends of the coupling lightguides 104 due to heat from the
light source).
[0666] FIG. 116 is a side view of a region of one embodiment of a
light emitting device 11600 comprising a stacked array of coupling
lightguides 104 disposed within an alignment cavity 11501 of an
alignment guide 11601 comprising an extended alignment arm 11602.
The stack of coupling lightguides 104 can be inserted into the
alignment cavity that registers the light input surface of the
coupling lightguides 104 in the x and z directions. The inner end
11603 of the alignment cavity 11501 can provide a stop for the
coupling lightguides 104 that sets a minimum separation distance
for the stack of coupling lightguides 104 and the light source 102.
Light 9903 from the light source 102 is directed into the coupling
lightguide 104.
[0667] FIG. 117 is a perspective view of one embodiment of a light
emitting device 11700 comprising a film-based lightguide 11702 and
a light reflecting optical element 11701 (shown in the FIG. 20 as
transparent to illustrate the reflecting light ray) that is also a
light collimating optical element and a light blocking element. The
light reflecting optical element 11701 has a region 11705 that
extends beyond the lightguide region 106 and wraps around the stack
of coupling lightguides 104 and has tab regions 11703 that fold
toward the light source 102 to form a light collimating element
11706. Light 11704 from the light source 102 is reflected off of
the tab region 11703 of the light collimating element 11706 and
becomes more collimated (smaller angular FWHM intensity) in the y-z
and y-x planes and enters the input edges 204 of the coupling
lightguides 104. Stray light that escapes a coupling lightguide 104
is blocked (reflected or absorbed in this embodiment) from exiting
directly from the stack of coupling lightguides 104 by the light
reflecting optical element 11701 that is also a light blocking
optical element. In another embodiment, the light reflecting
optical element 11701 may be optically coupled to the film-based
lightguide 11702 by a pressure sensitive adhesive and the light
reflecting optical element 11701 may diffusely reflect, specularly
reflect, or a combination thereof, a portion of the incident light.
In a further embodiment, the light reflecting optical element 11701
is a low contact area cover or comprises surface relief features in
contact with the film-based lightguide 11702.
EXAMPLES
[0668] Certain embodiments are illustrated in the following
example(s). The following examples are given for the purpose of
illustration, but not for limiting the scope or spirit of the
invention.
[0669] In one embodiment, coupling lightguides are formed by
cutting strips at one or more ends of a film which forms coupling
lightguides (strips) and a lightguide region (remainder of the
film). On the free end of the strips, the strips are bundled
together into an arrangement much thicker than the thickness of the
film itself. On the other end, they remain physically and optically
attached and aligned to the larger film lightguide. The film
cutting is achieved by stamping, laser-cutting, mechanical cutting,
water-jet cutting, local melting or other film processing methods.
Preferably the cut results in an optically smooth surface to
promote total internal reflection of the light to improve hot
guiding through the length of the strips. A light source is coupled
to the bundled strips. The strips are arranged so that light
propagates through them via total internal reflection and is
transferred into the lightguide region. The bundled strips form a
light input edge having a thickness much greater than the film
lightguide region. The light input edge of the bundled strips
defines a light input surface to facilitate more efficient transfer
of light from the light source into the lightguide, as compared to
conventional methods that couple to the edge or top of the film.
The strips can be melted or mechanically forced together at the
input to improve coupling efficiency. If the bundle is square
shaped, the length of one of its sides I, is given by I.about.
(w.times.t) where w is the total width of the lightguide input edge
and t is the thickness of the film. For example, a 0.1 mm thick
film with 1 m edge would give a square input bundle with dimensions
of 1 cm.times.1 cm. Considering these dimensions, the bundle is
much easier to couple light into compared to coupling along the
length of the film when using typical light sources (e.g.
incandescent, fluorescent; metal halide, xenon and LED sources).
The improvement in coupling efficiency and cost is particularly
pronounced at film thicknesses below 0.25 mm, because that
thickness is approximately the size of many LED and laser diode
chips. Therefore, it would be difficult and/or expensive to
manufacture micro-optics to efficiently couple light into the film
edge from an LED chip because of the etendue and manufacturing
tolerance limitations. Also, it should be noted that the folds in
the slots are not creases but rather have some radius of curvature
to allow effective light transfer. Typically the fold radius of
curvature will be at least ten times the thickness of the film.
[0670] An example of one embodiment that can be brought to practice
is given here. The assembly starts with 0.25 mm thick polycarbonate
film that is 40 cm wide and 100 cm long. A cladding layer of a
lower refractive index material of approximately 0.01 mm thickness
is disposed on the top and bottom surface of the film. The cladding
layer can be added by coating or co-extruding a material with lower
refractive index onto the film core. One edge of the film is
mechanically cut into 40 strips of 1 cm width using a sharp cutting
tool such as a razor blade. The edges of the slots are then exposed
to a flame to improve the smoothness for optical transfer. The
slots are combined into a bundle of approximately 1 cm.times.1 cm
cross-section. To the end of the bundle a number of different types
of light sources can be coupled (e.g. xenon, metal halide,
incandescent, LED or Laser). Light propagates through the bundle
into the film and out of the image area Light may be extracted from
the film lightguide by laser etching into the film, which adds a
surface roughness that results in frustrated total internal
reflectance. Multiple layers of film can be combined to make
multi-color or dynamic signs.
[0671] An example of one embodiment a film based light emitting
device that has been brought to practice is described here. The
apparatus began with a 381 micron thick polycarbonate film which
was 457 mm wide and 762 mm long. The 457 mm edge of the film is cut
into 635 mm wide strips using an array of razor blades. These
strips are grouped into three 152.4 mm wide sets of strips, which
are further split into two equal sets that were folded towards each
other and stacked separately into 4.19 mm by 6.35 mm stacks. Each
of the three pairs of stacks was then combined together in the
center in the method to create a combined and singular input stack
of 8.38 mm by 6.35 mm size. An LED module, MCE LED module from Cree
Inc., is coupled into each of the three input stacks. Light emitted
from the LED enters the film stack with an even input, and a
portion of this light remains within each of the 15 mil strips via
total internal reflections while propagating through the strip. The
light continues to propagate down each strip as they break apart in
their separate configurations, before entering the larger
lightguide. Furthermore, a finned aluminum heat sink was placed
down the length of each of the three coupling apparatuses to
dissipate heat from the LED. This assembly shows a compact design
that can be aligned in a linear array, to create uniform light.
[0672] A method to manufacture one embodiment of a multilayer
frontlight comprising three film-based lightguides is as follows.
Three layers of thin film lightguides (<250 microns) are
laminated to each other with a layer of lower refractive index
material between them (e.g. methyl-based silicone PSA). Then, an
angled beam of light, ions or mechanical substance (i.e. particles
and/or fluid) patterns lines or spots into the film. If necessary,
a photosensitive material should be layered on each material
beforehand. The angle of the beam is such that the extraction
features on the layers have the proper offset. The angle of the
beam is dictated by the lightguide thickness and the width of the
pixels and is given by .theta.=tan.sup.-1(t/w), where .theta. is
the relative angle of light to the plane of the lightguide, t is
the lightguide and cladding thickness and w is the width of the
pixels. Ideally the extraction features direct the light primarily
in a direction toward the intended pixel to minimize cross-talk.
Light from red, green, and blue LEDs are input into three light
input couplers formed by folding the coupling lightguides each of
the three lightguides.
[0673] In one embodiment, a light emitting device includes a light
source having an optical axis, a relative position maintaining
element, and a lightguide comprising a film having a thickness not
greater than 0.5 millimeters. The lightguide includes a lightguide
region and an array of coupling lightguides continuous with the
lightguide region, wherein each coupling lightguide of the array of
coupling lightguides terminates in an edge and at least one of the
array of coupling lightguides is folded at least partially around
the relative position maintaining element such that the edges of
the array of coupling lightguides form a stack defining a light
input surface. Light from the light source enters into the light
input surface and propagates by total internal reflection within
each coupling lightguide to the lightguide region and the relative
position maintaining element extends past the light input surface
in a direction parallel to the optical axis.
[0674] In a particular embodiment, the relative position
maintaining element extends past the light source in a direction
parallel to the optical axis. 4. The light emitting device may
include a light redirecting optical element positioned to direct
the light from the light source to the light input surface. In a
further embodiment, at least one of the light source and the light
redirecting optical element is coupled to the relative position
maintaining element.
[0675] In a further embodiment, the relative position maintaining
element comprises an array of guide members and the at least one of
the array coupling lightguide is folded at least partially around a
guide member.
[0676] In one embodiment, a display comprises the light emitting
device and a spatial light modulator, wherein the light emitting
device illuminates the spatial light modulator.
[0677] In another embodiment, a light emitting device includes a
light source. A lightguide comprises a film having a thickness not
greater than 0.5 millimeters. The lightguide includes a lightguide
region and an array of coupling lightguides continuous with the
lightguide region, wherein each coupling lightguide of the array of
coupling lightguides terminates in an edge and at least one of the
array of coupling lightguides is folded such that the edges of the
array of coupling lightguides form a stack defining a light input
surface. A light redirecting optical element is positioned to
direct light from the light source to the light input surface such
that the light propagates by total internal reflection within each
coupling lightguide to the lightguide region. The light redirecting
optical element comprises an alignment guide configured to align
the light redirecting optical element to the light input
surface.
[0678] In a particular embodiment, the alignment guide aligns the
light redirecting optical element to the light input surface in a
direction of the stack. In a further embodiment, the alignment
guide constrains the edges of the coupling lightguides in a
direction of the stack. In one embodiment, the light redirecting
optical element is a secondary optic for the light source. The
light redirecting optical element collimates the light from the
light source such that the light incident on the light input
surface has an angular full-width at half maximum intensity less
than 60 degrees in a plane orthogonal to the light input surface.
In one embodiment, the light emitting device includes a relative
position maintaining element comprising an array of guide members
and the at least one of the array of coupling lightguide is folded
at least partially around the array of guide members.
[0679] In a further embodiment, a display comprises the light
emitting device and a spatial light modulator, wherein the light
emitting device illuminates the spatial light modulator.
[0680] In another embodiment, a light emitting device includes a
light source and a lightguide formed from a film having a thickness
not greater than 0.5 millimeters. The lightguide includes a
lightguide region and an array of coupling lightguides continuous
with the lightguide region, wherein each coupling lightguide of the
array of coupling lightguides terminates in an edge and at least
one of the array of coupling lightguides is folded such that the
edges of the array of coupling lightguides form a stack defining a
light input surface. The light emitting device includes an
alignment guide defining a cavity, wherein the light input surface
is positioned within the cavity and light from the light source
propagates into the light input surface such that that the light
propagates by total internal reflection within each coupling
lightguide to the lightguide region. In one embodiment, the
alignment guide redirects light from the light source such that the
redirected light is more collimated in a first plane orthogonal to
an optical axis of the light from the light source. In a particular
embodiment, the first plane is parallel to a direction of the
stack. In one embodiment, the light incident on the light input
surface has an angular full-width at half maximum intensity less
than 60 degrees in a plane orthogonal to the light input
surface.
[0681] In a further embodiment, a display comprising a light
emitting device and a spatial light modulator, wherein the light
emitting device illuminates the spatial light modulator.
[0682] In yet another embodiment, a method of manufacturing a light
emitting device includes separating a plurality of regions in a
film with a thickness less than 0.5 millimeters to form a plurality
of coupling lightguides continuous with a lightguide region of the
film, folding at least one coupling lightguide of the plurality of
coupling lightguides such that ends of the plurality of coupling
lightguides form a stack defining a light input surface, and
positioning a light redirecting optical element to receive light
from a light source and transmit the light to the light input
surface such that the light propagates within each coupling
lightguide to the lightguide region, wherein the light redirecting
optical element comprises one of an alignment guide and a cavity
defined within the light redirecting optical element configured to
align the light input surface with the light redirecting optical
element. In a particular embodiment, positioning a light
redirecting optical element comprises positioning the light input
surface within the cavity.
[0683] Exemplary embodiments of light emitting devices and methods
for making or producing the same are described above in detail. The
devices, components, and methods are not limited to the specific
embodiments described herein, but rather, the devices, components
of the devices and/or steps of the methods may be utilized
independently and separately from other devices, components and/or
steps described herein. Further, the described devices, components
and/or the described methods steps can also be defined in, or used
in combination with, other devices and/or methods, and are not
limited to practice with only the devices and methods as described
herein.
[0684] While the disclosure includes various specific embodiments,
those skilled in the art will recognize that the embodiments can be
practiced with modification within the spirit and scope of the
disclosure and the claims.
EQUIVALENTS
[0685] Those skilled in the art will recognize, or be able to
ascertain using no more than routine experimentation, numerous
equivalents to the specific procedures described herein. Such
equivalents are considered to be within the scope of the invention.
Various substitutions, alterations, and modifications may be made
to the invention without departing from the spirit and scope of the
invention. Other aspects, advantages, and modifications are within
the scope of the invention. This application is intended to cover
any adaptations or variations of the specific embodiments discussed
herein. Therefore, it is intended that this disclosure be limited
only by the claims and the equivalents thereof.
[0686] Unless otherwise indicated, all numbers expressing feature
sizes, amounts, and physical properties used in the specification
and claims are to be understood as being modified by the term
"about". Accordingly, unless indicated to the contrary, the
numerical parameters set forth in the foregoing specification and
attached claims are approximations that can vary depending upon the
desired properties sought to be obtained by those skilled in the
art utilizing the teachings disclosed herein. Unless indicated to
the contrary, all tests and properties are measured at an ambient
temperature of 25 degrees Celsius or the environmental temperature
within or near the device when powered on (when indicated) under
constant ambient room temperature of 25 degrees Celsius,
* * * * *