U.S. patent application number 13/733091 was filed with the patent office on 2013-06-06 for light turning device with prismatic light turning features.
This patent application is currently assigned to Qualcomm Mems Technologies, Inc.. The applicant listed for this patent is Qualcomm Mems Techologies, Inc.. Invention is credited to Ion Bita, Kasra Khazeni, Manish Kothari, Kollengode S. Narayanan, Gang Xu.
Application Number | 20130141938 13/733091 |
Document ID | / |
Family ID | 41724666 |
Filed Date | 2013-06-06 |
United States Patent
Application |
20130141938 |
Kind Code |
A1 |
Khazeni; Kasra ; et
al. |
June 6, 2013 |
LIGHT TURNING DEVICE WITH PRISMATIC LIGHT TURNING FEATURES
Abstract
A light guide device includes a light guide body and two or more
pluralities of spaced-apart slits. The slits are formed by
undercuts in the light guide body. Sidewalls of the slits form
facets that redirect light impinging on the facets. In some
embodiments, the light guide body is attached to a light source.
The light source emits light that is injected into the light guide
body and the slits redirect the light out of the light guide body
and towards a desired target. In some embodiments, the target is a
display and a first plurality of slits directs light from the light
source across the light guide body and over the face of the
display. A second plurality of slits then directs light out of the
light guide body and towards the display.
Inventors: |
Khazeni; Kasra; (San Jose,
CA) ; Kothari; Manish; (Cupertino, CA) ; Xu;
Gang; (Cupertino, CA) ; Bita; Ion; (San Jose,
CA) ; Narayanan; Kollengode S.; (Cupertino,
CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Qualcomm Mems Techologies, Inc.; |
San Diego |
CA |
US |
|
|
Assignee: |
Qualcomm Mems Technologies,
Inc.
San Diego
CA
|
Family ID: |
41724666 |
Appl. No.: |
13/733091 |
Filed: |
January 2, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
12552124 |
Sep 1, 2009 |
8358266 |
|
|
13733091 |
|
|
|
|
61093695 |
Sep 2, 2008 |
|
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Current U.S.
Class: |
362/608 ;
264/1.37 |
Current CPC
Class: |
G02B 6/0035 20130101;
G02B 6/0015 20130101; G02B 6/0065 20130101; B29D 11/00663 20130101;
G02B 6/0028 20130101 |
Class at
Publication: |
362/608 ;
264/1.37 |
International
Class: |
F21V 8/00 20060101
F21V008/00 |
Claims
1. A method for manufacturing an illumination device, comprising:
providing a body of light propagating material, the material
supporting propagation of light through a length of the body; and
forming first and second pluralities of spaced-apart undercuts in
different sides the body.
2. The method of claim 1, wherein the different sides include a
first edge and a major side of the body.
3. The method of claim 2, wherein the second plurality of undercuts
are configured to redirect light, propagating from a second edge
crossing the first edge, across the body of light propagating
material towards a third edge opposite the first edge; and wherein
the first plurality of undercuts is configured to redirect the
light redirected by the second plurality of undercuts out through a
second major side.
4. The method of claim 1, wherein the different sides include a
first major side of the body and a second major side of the
body.
5. The method of claim 4, wherein the first and second pluralities
of undercuts are configured to redirect light, propagating from a
direction of a first edge, out through the second major side.
6. The method of claim 1, further comprising depositing an
anti-reflective coating on surfaces of the undercuts.
7. The method of claim 1, wherein forming the plurality of
spaced-apart undercuts includes extruding the light propagating
material through a die.
8. The method of claim 1, wherein forming the plurality of
spaced-apart undercuts includes casting the light propagating
material in a mold.
9. The method of claim 1, wherein forming the plurality of
spaced-apart undercuts includes injection molding light propagating
material through a mold.
10. The method of claim 1, wherein forming the plurality of
spaced-apart undercuts includes embossing the body of light
propagating material.
11. The method of claim 1, wherein forming the plurality of
spaced-apart undercuts includes machining or laser ablating the
body of light propagating material.
12. The method of claim 1, further including affixing a display,
the display including a plurality of pixels, to the body of light
propagating material.
13. The method of claim 1, wherein a density of at least one of the
first or second spaced-apart undercuts increases with increasing
distance from a light input edge of the body light propagating
material.
14. The method of claim 1, wherein a surface area of at least one
of the first or second spaced-apart undercuts increases with
increasing distance from a light input edge of the body light
propagating material.
15. The method of claim 1, wherein an angle formed between an
undercut and the side in which the undercut is formed varies among
at least one of the first or second plurality of undercuts.
16. The method of claim 1, wherein an angle formed between an
undercut and the side in which the undercut is formed varies
between the first and second pluralities of undercuts.
17. The method of claim 1, wherein a surface area of the undercuts
varies between the first and second pluralities of undercuts.
18. The method of claim 1, wherein the undercuts define
spaced-apart concentric semicircles.
19. A illumination device fabricated by the method of claim 1.
Description
REFERENCE TO RELATED APPLICATION
[0001] This application is a divisional of U.S. patent application
Ser. No. 12/552,124, filed Sep. 1, 2009, entitled "LIGHT TURNING
DEVICE WITH PRISMATIC LIGHT TURNING FEATURES," which claims
priority under 35 U.S.C. .sctn.119(e) of U.S. Provisional Patent
Application No. 61/093,695, filed Sep. 2, 2008, both of which are
assigned to the assignee hereof. The disclosures of the prior
applications are considered part of this disclosure and are
incorporated by reference in their entireties.
BACKGROUND
[0002] 1. Field of the Invention
[0003] This invention relates generally to light turning devices.
More particularly, this invention relates to light turning devices
utilizing prismatic structures to guide light to, for example,
illuminate a display. This invention also relates to methods of use
and fabrication of these devices.
[0004] 2. Description of Related Technology
[0005] Microelectromechanical systems (MEMS) include micro
mechanical elements, actuators, and electronics. Micromechanical
elements may be created using deposition, etching, and/or other
micromachining processes that etch away parts of substrates and/or
deposited material layers or that add layers to form electrical and
electromechanical devices. One type of MEMS device is called an
interferometric modulator. As used herein, the term interferometric
modulator or interferometric light modulator refers to a device
that selectively absorbs and/or reflects light using the principles
of optical interference. In certain embodiments, an interferometric
modulator may comprise a pair of conductive plates, one or both of
which may be transparent and/or reflective in whole or part and
capable of relative motion upon application of an appropriate
electrical signal. In a particular embodiment, one plate may
comprise a stationary layer deposited on a substrate and the other
plate may comprise a metallic membrane separated from the
stationary layer by an air gap. As described herein in more detail,
the position of one plate in relation to another can change the
optical interference of light incident on the interferometric
modulator. Such devices have a wide range of applications, and it
would be beneficial in the art to utilize and/or modify the
characteristics of these types of devices so that their features
can be exploited in improving existing products and creating new
products that have not yet been developed.
SUMMARY
[0006] In some embodiments, a light guide apparatus is provided.
The apparatus comprises a light guide body formed of a light
propagating material that supports the propagation of light through
a length of the light guide body. The light guide body is defined
by a plurality of exterior surfaces. A first of the exterior
surfaces comprises a first plurality of spaced-apart slits
configured to redirect light incident on the light guide body, with
each slit formed by an undercut in the first exterior surface. A
second of the exterior surfaces comprises a second plurality of
spaced-apart slits configured to redirect light incident on the
light guide body, with each slit formed by an undercut in the
second exterior surface.
[0007] In some other embodiments, an illumination apparatus is
provided. The apparatus comprises a first means for generating
light and directing the light to propagate through a light turning
body; a second means for redirecting the light propagating through
the light turning body; and a third means for redirecting the light
propagating through the light turning body.
[0008] In yet other embodiments, a method for illumination is
provided. The method comprises propagating light through a light
turning body. Light propagating through the body is redirected by
impinging the light on facets of a first and a second plurality of
slits. The pluralities of slits are formed by undercuts in two
surfaces of the light turning body.
[0009] In some other embodiments, a method for manufacturing an
illumination device is provided. The method comprises providing a
body of light propagating material that supports the propagation of
light through a length of the body. First and second pluralities of
spaced-apart undercuts are formed in different sides of the body.
In some other embodiments, the illumination device formed by this
method is provided.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1 is an isometric view depicting a portion of one
embodiment of an interferometric modulator display in which a
movable reflective layer of a first interferometric modulator is in
a relaxed position and a movable reflective layer of a second
interferometric modulator is in an actuated position.
[0011] FIG. 2 is a system block diagram illustrating one embodiment
of an electronic device incorporating a 3.times.3 interferometric
modulator display.
[0012] FIG. 3 is a diagram of movable mirror position versus
applied voltage for one exemplary embodiment of an interferometric
modulator of FIG. 1.
[0013] FIG. 4 is an illustration of a set of row and column
voltages that may be used to drive an interferometric modulator
display.
[0014] FIG. 5A illustrates one exemplary frame of display data in
the 3.times.3 interferometric modulator display of FIG. 2.
[0015] FIG. 5B illustrates one exemplary timing diagram for row and
column signals that may be used to write the frame of FIG. 5A.
[0016] FIGS. 6A and 6B are system block diagrams illustrating an
embodiment of a visual display device comprising a plurality of
interferometric modulators.
[0017] FIG. 7A is a cross section of the device of FIG. 1.
[0018] FIG. 7B is a cross section of an alternative embodiment of
an interferometric modulator.
[0019] FIG. 7C is a cross section of another alternative embodiment
of an interferometric modulator.
[0020] FIG. 7D is a cross section of yet another alternative
embodiment of an interferometric modulator.
[0021] FIG. 7E is a cross section of an additional alternative
embodiment of an interferometric modulator.
[0022] FIG. 8 is a cross section of a display device.
[0023] FIG. 9 is an enlargement of a portion of the cross section
of FIG. 8.
[0024] FIG. 10A is a cross section of an embodiment of a light
turning feature.
[0025] FIG. 10B is a cross section of another embodiment of a light
turning feature.
[0026] FIG. 10C is a cross section of yet another embodiment of a
light turning feature.
[0027] FIG. 11A is a top plan view of an embodiment of a display
device.
[0028] FIG. 11B is a cross section of the display device of FIG.
11A.
[0029] FIGS. 11C-11E are top plan views of embodiments of display
devices.
[0030] FIGS. 12A-12B are cross sections of embodiments of display
devices.
[0031] FIGS. 13A-13C are top plan views of embodiments of display
devices.
DETAILED DESCRIPTION
[0032] The following detailed description is directed to certain
specific embodiments. However, the teachings herein can be applied
in a multitude of different ways. In this description, reference is
made to the drawings wherein like or similar parts are designated
with like numerals throughout. The embodiments may be implemented
in any device that is configured to display an image, whether in
motion (e.g., video) or stationary (e.g., still image), and whether
textual or pictorial. More particularly, it is contemplated that
the embodiments may be implemented in or associated with a variety
of electronic devices such as, but not limited to, mobile
telephones, wireless devices, personal data assistants (PDAs),
hand-held or portable computers, GPS receivers/navigators, cameras,
MP3 players, camcorders, game consoles, wrist watches, clocks,
calculators, television monitors, flat panel displays, computer
monitors, auto displays (e.g., odometer display, etc.), cockpit
controls and/or displays, display of camera views (e.g., display of
a rear view camera in a vehicle), electronic photographs,
electronic billboards or signs, projectors, architectural
structures, packaging, and aesthetic structures (e.g., display of
images on a piece of jewelry). MEMS devices of similar structure to
those described herein can also be used in non-display applications
such as in electronic switching devices.
[0033] Some embodiments disclosed herein include a light guide
having undercuts in the body of the light guide. The undercuts form
prismatic features, also referred to as slits, that turn or
redirect light propagating through the light guide body. For
example, the walls of the undercuts form facets that reflect light
in a desired direction. In some embodiments, a light source is
connected to the light guide body. Light from the light source is
injected into the light guide body, propagates through the body and
contacts the facets of the undercuts. The facets of the slits
redirect the light out of the light guide body, e.g., to a display
formed of, e.g., interferometric modulators. In some embodiments,
first and second pluralities of slits are provided on opposite
major surfaces of the light guide body. The slits are configured to
redirect the light out of a common major surface.
[0034] In some other embodiments, a plurality of slits is formed in
a line light source. For example, the slits are positioned and
angled to turn light injected into the line light source from a
point light emitter at the end of the line light source. The turned
light can, e.g., be expelled out of the line light source along the
length of the light source or, in some other embodiments, to an
area containing a second plurality of slits. The second plurality
of slits can turn the light towards a display.
[0035] One interferometric modulator display embodiment comprising
an interferometric MEMS display element is illustrated in FIG. 1.
In these devices, the pixels are in either a bright or dark state.
In the bright ("relaxed" or "open") state, the display element
reflects a large portion of incident visible light to a user. When
in the dark ("actuated" or "closed") state, the display element
reflects little incident visible light to the user. Depending on
the embodiment, the light reflectance properties of the "on" and
"off" states may be reversed. MEMS pixels can be configured to
reflect predominantly at selected colors, allowing for a color
display in addition to black and white.
[0036] FIG. 1 is an isometric view depicting two adjacent pixels in
a series of pixels of a visual display, wherein each pixel
comprises a MEMS interferometric modulator. In some embodiments, an
interferometric modulator display comprises a row/column array of
these interferometric modulators. Each interferometric modulator
includes a pair of reflective layers positioned at a variable and
controllable distance from each other to form a resonant optical
gap with at least one variable dimension. In one embodiment, one of
the reflective layers may be moved between two positions. In the
first position, referred to herein as the relaxed position, the
movable reflective layer is positioned at a relatively large
distance from a fixed partially reflective layer. In the second
position, referred to herein as the actuated position, the movable
reflective layer is positioned more closely adjacent to the
partially reflective layer. Incident light that reflects from the
two layers interferes constructively or destructively depending on
the position of the movable reflective layer, producing either an
overall reflective or non-reflective state for each pixel.
[0037] The depicted portion of the pixel array in FIG. 1 includes
two adjacent interferometric modulators 12a and 12b. In the
interferometric modulator 12a on the left, a movable reflective
layer 14a is illustrated in a relaxed position at a predetermined
distance from an optical stack 16a, which includes a partially
reflective layer. In the interferometric modulator 12b on the
right, the movable reflective layer 14b is illustrated in an
actuated position adjacent to the optical stack 16b.
[0038] The optical stacks 16a and 16b (collectively referred to as
optical stack 16), as referenced herein, typically comprise several
fused layers, which can include an electrode layer, such as indium
tin oxide (ITO), a partially reflective layer, such as chromium,
and a transparent dielectric. The optical stack 16 is thus
electrically conductive, partially transparent and partially
reflective, and may be fabricated, for example, by depositing one
or more of the above layers onto a transparent substrate 20. The
partially reflective layer can be formed from a variety of
materials that are partially reflective such as various metals,
semiconductors, and dielectrics. The partially reflective layer can
be formed of one or more layers of materials, and each of the
layers can be formed of a single material or a combination of
materials.
[0039] In some embodiments, the layers of the optical stack 16 are
patterned into parallel strips, and may form row electrodes in a
display device as described further below. The movable reflective
layers 14a, 14b may be formed as a series of parallel strips of a
deposited metal layer or layers (orthogonal to the row electrodes
of 16a, 16b) to form columns deposited on top of posts 18 and an
intervening sacrificial material deposited between the posts 18.
When the sacrificial material is etched away, the movable
reflective layers 14a, 14b are separated from the optical stacks
16a, 16b by a defined gap 19. A highly conductive and reflective
material such as aluminum may be used for the reflective layers 14,
and these strips may form column electrodes in a display device.
Note that FIG. 1 may not be to scale. In some embodiments, the
spacing between posts 18 may be on the order of 10-100 um, while
the gap 19 may be on the order of <1000 Angstroms.
[0040] With no applied voltage, the gap 19 remains between the
movable reflective layer 14a and optical stack 16a, with the
movable reflective layer 14a in a mechanically relaxed state, as
illustrated by the pixel 12a in FIG. 1. However, when a potential
(voltage) difference is applied to a selected row and column, the
capacitor formed at the intersection of the row and column
electrodes at the corresponding pixel becomes charged, and
electrostatic forces pull the electrodes together. If the voltage
is high enough, the movable reflective layer 14 is deformed and is
forced against the optical stack 16. A dielectric layer (not
illustrated in this Figure) within the optical stack 16 may prevent
shorting and control the separation distance between layers 14 and
16, as illustrated by actuated pixel 12b on the right in FIG. 1.
The behavior is the same regardless of the polarity of the applied
potential difference.
[0041] FIGS. 2 through 5B illustrate one exemplary process and
system for using an array of interferometric modulators in a
display application.
[0042] FIG. 2 is a system block diagram illustrating one embodiment
of an electronic device that may incorporate interferometric
modulators. The electronic device includes a processor 21 which may
be any general purpose single- or multi-chip microprocessor such as
an ARM.RTM., Pentium.RTM., 8051, MIPS.RTM., Power PC.RTM., or
ALPHA.RTM., or any special purpose microprocessor such as a digital
signal processor, microcontroller, or a programmable gate array. As
is conventional in the art, the processor 21 may be configured to
execute one or more software modules. In addition to executing an
operating system, the processor may be configured to execute one or
more software applications, including a web browser, a telephone
application, an email program, or any other software
application.
[0043] In one embodiment, the processor 21 is also configured to
communicate with an array driver 22. In one embodiment, the array
driver 22 includes a row driver circuit 24 and a column driver
circuit 26 that provide signals to a display array or panel 30. The
cross section of the array illustrated in FIG. 1 is shown by the
lines 1-1 in FIG. 2. Note that although FIG. 2 illustrates a
3.times.3 array of interferometric modulators for the sake of
clarity, the display array 30 may contain a very large number of
interferometric modulators, and may have a different number of
interferometric modulators in rows than in columns (e.g., 300
pixels per row by 190 pixels per column).
[0044] FIG. 3 is a diagram of movable mirror position versus
applied voltage for one exemplary embodiment of an interferometric
modulator of FIG. 1. For MEMS interferometric modulators, the
row/column actuation protocol may take advantage of a hysteresis
property of these devices as illustrated in FIG. 3. An
interferometric modulator may require, for example, a 10 volt
potential difference to cause a movable layer to deform from the
relaxed state to the actuated state. However, when the voltage is
reduced from that value, the movable layer maintains its state as
the voltage drops back below 10 volts. In the exemplary embodiment
of FIG. 3, the movable layer does not relax completely until the
voltage drops below 2 volts. There is thus a range of voltage,
about 3 to 7 V in the example illustrated in FIG. 3, where there
exists a window of applied voltage within which the device is
stable in either the relaxed or actuated state. This is referred to
herein as the "hysteresis window" or "stability window." For a
display array having the hysteresis characteristics of FIG. 3, the
row/column actuation protocol can be designed such that during row
strobing, pixels in the strobed row that are to be actuated are
exposed to a voltage difference of about 10 volts, and pixels that
are to be relaxed are exposed to a voltage difference of close to
zero volts. After the strobe, the pixels are exposed to a steady
state or bias voltage difference of about 5 volts such that they
remain in whatever state the row strobe put them in. After being
written, each pixel sees a potential difference within the
"stability window" of 3-7 volts in this example. This feature makes
the pixel design illustrated in FIG. 1 stable under the same
applied voltage conditions in either an actuated or relaxed
pre-existing state. Since each pixel of the interferometric
modulator, whether in the actuated or relaxed state, is essentially
a capacitor formed by the fixed and moving reflective layers, this
stable state can be held at a voltage within the hysteresis window
with almost no power dissipation. Essentially no current flows into
the pixel if the applied potential is fixed.
[0045] As described further below, in typical applications, a frame
of an image may be created by sending a set of data signals (each
having a certain voltage level) across the set of column electrodes
in accordance with the desired set of actuated pixels in the first
row. A row pulse is then applied to a first row electrode,
actuating the pixels corresponding to the set of data signals. The
set of data signals is then changed to correspond to the desired
set of actuated pixels in a second row. A pulse is then applied to
the second row electrode, actuating the appropriate pixels in the
second row in accordance with the data signals. The first row of
pixels are unaffected by the second row pulse, and remain in the
state they were set to during the first row pulse. This may be
repeated for the entire series of rows in a sequential fashion to
produce the frame. Generally, the frames are refreshed and/or
updated with new image data by continually repeating this process
at some desired number of frames per second. A wide variety of
protocols for driving row and column electrodes of pixel arrays to
produce image frames may be used.
[0046] FIGS. 4 and 5A and 5B illustrate one possible actuation
protocol for creating a display frame on the 3.times.3 array of
FIG. 2. FIG. 4 illustrates a possible set of column and row voltage
levels that may be used for pixels exhibiting the hysteresis curves
of FIG. 3. In the FIG. 4 embodiment, actuating a pixel involves
setting the appropriate column to -V.sub.bias, and the appropriate
row to +.DELTA.V, which may correspond to -5 volts and +5 volts
respectively Relaxing the pixel is accomplished by setting the
appropriate column to +V.sub.bias, and the appropriate row to the
same +.DELTA.V, producing a zero volt potential difference across
the pixel. In those rows where the row voltage is held at zero
volts, the pixels are stable in whatever state they were originally
in, regardless of whether the column is at +V.sub.bias, or
-V.sub.bias. As is also illustrated in FIG. 4, voltages of opposite
polarity than those described above can be used, e.g., actuating a
pixel can involve setting the appropriate column to +V.sub.bias,
and the appropriate row to -.DELTA.V. In this embodiment, releasing
the pixel is accomplished by setting the appropriate column to
-V.sub.bias, and the appropriate row to the same -.DELTA.V,
producing a zero volt potential difference across the pixel.
[0047] FIG. 5B is a timing diagram showing a series of row and
column signals applied to the 3.times.3 array of FIG. 2 which will
result in the display arrangement illustrated in FIG. 5A, where
actuated pixels are non-reflective. Prior to writing the frame
illustrated in FIG. 5A, the pixels can be in any state, and in this
example, all the rows are initially at 0 volts, and all the columns
are at +5 volts. With these applied voltages, all pixels are stable
in their existing actuated or relaxed states.
[0048] In the FIG. 5A frame, pixels (1,1), (1,2), (2,2), (3,2) and
(3,3) are actuated. To accomplish this, during a "line time" for
row 1, columns 1 and 2 are set to -5 volts, and column 3 is set to
+5 volts. This does not change the state of any pixels, because all
the pixels remain in the 3-7 volt stability window. Row 1 is then
strobed with a pulse that goes from 0, up to 5 volts, and back to
zero. This actuates the (1,1) and (1,2) pixels and relaxes the
(1,3) pixel. No other pixels in the array are affected. To set row
2 as desired, column 2 is set to -5 volts, and columns 1 and 3 are
set to +5 volts. The same strobe applied to row 2 will then actuate
pixel (2,2) and relax pixels (2,1) and (2,3). Again, no other
pixels of the array are affected. Row 3 is similarly set by setting
columns 2 and 3 to -5 volts, and column 1 to +5 volts. The row 3
strobe sets the row 3 pixels as shown in FIG. 5A. After writing the
frame, the row potentials are zero, and the column potentials can
remain at either +5 or -5 volts, and the display is then stable in
the arrangement of FIG. 5A. The same procedure can be employed for
arrays of dozens or hundreds of rows and columns. The timing,
sequence, and levels of voltages used to perform row and column
actuation can be varied widely within the general principles
outlined above, and the above example is exemplary only, and any
actuation voltage method can be used with the systems and methods
described herein.
[0049] FIGS. 6A and 6B are system block diagrams illustrating an
embodiment of a display device 40. The display device 40 can be,
for example, a cellular or mobile telephone. However, the same
components of display device 40 or slight variations thereof are
also illustrative of various types of display devices such as
televisions and portable media players.
[0050] The display device 40 includes a housing 41, a display 30,
an antenna 43, a speaker 45, an input device 48, and a microphone
46. The housing 41 is generally formed from any of a variety of
manufacturing processes, including injection molding, and vacuum
forming. In addition, the housing 41 may be made from any of a
variety of materials, including but not limited to plastic, metal,
glass, rubber, and ceramic, or a combination thereof. In one
embodiment the housing 41 includes removable portions (not shown)
that may be interchanged with other removable portions of different
color, or containing different logos, pictures, or symbols.
[0051] The display 30 of exemplary display device 40 may be any of
a variety of displays, including a bi-stable display, as described
herein. In other embodiments, the display 30 includes a flat-panel
display, such as plasma, EL, OLED, STN LCD, or TFT LCD as described
above, or a non-flat-panel display, such as a CRT or other tube
device,. However, for purposes of describing the present
embodiment, the display 30 includes an interferometric modulator
display, as described herein.
[0052] The components of one embodiment of exemplary display device
40 are schematically illustrated in FIG. 6B. The illustrated
exemplary display device 40 includes a housing 41 and can include
additional components at least partially enclosed therein. For
example, in one embodiment, the exemplary display device 40
includes a network interface 27 that includes an antenna 43 which
is coupled to a transceiver 47. The transceiver 47 is connected to
a processor 21, which is connected to conditioning hardware 52. The
conditioning hardware 52 may be configured to condition a signal
(e.g. filter a signal). The conditioning hardware 52 is connected
to a speaker 45 and a microphone 46. The processor 21 is also
connected to an input device 48 and a driver controller 29. The
driver controller 29 is coupled to a frame buffer 28, and to an
array driver 22, which in turn is coupled to a display array 30. A
power supply 50 provides power to all components as required by the
particular exemplary display device 40 design.
[0053] The network interface 27 includes the antenna 43 and the
transceiver 47 so that the exemplary display device 40 can
communicate with one ore more devices over a network. In one
embodiment the network interface 27 may also have some processing
capabilities to relieve requirements of the processor 21. The
antenna 43 is any antenna for transmitting and receiving signals.
In one embodiment, the antenna transmits and receives RF signals
according to the IEEE 802.11 standard, including IEEE 802.11(a),
(b), or (g). In another embodiment, the antenna transmits and
receives RF signals according to the BLUETOOTH standard. In the
case of a cellular telephone, the antenna is designed to receive
CDMA, GSM, AMPS, W-CDMA, or other known signals that are used to
communicate within a wireless cell phone network. The transceiver
47 pre-processes the signals received from the antenna 43 so that
they may be received by and further manipulated by the processor
21. The transceiver 47 also processes signals received from the
processor 21 so that they may be transmitted from the exemplary
display device 40 via the antenna 43.
[0054] In an alternative embodiment, the transceiver 47 can be
replaced by a receiver. In yet another alternative embodiment,
network interface 27 can be replaced by an image source, which can
store or generate image data to be sent to the processor 21. For
example, the image source can be a digital video disc (DVD) or a
hard-disc drive that contains image data, or a software module that
generates image data.
[0055] Processor 21 generally controls the overall operation of the
exemplary display device 40. The processor 21 receives data, such
as compressed image data from the network interface 27 or an image
source, and processes the data into raw image data or into a format
that is readily processed into raw image data. The processor 21
then sends the processed data to the driver controller 29 or to
frame buffer 28 for storage. Raw data typically refers to the
information that identifies the image characteristics at each
location within an image. For example, such image characteristics
can include color, saturation, and gray-scale level.
[0056] In one embodiment, the processor 21 includes a
microcontroller, CPU, or logic unit to control operation of the
exemplary display device 40. Conditioning hardware 52 generally
includes amplifiers and filters for transmitting signals to the
speaker 45, and for receiving signals from the microphone 46.
Conditioning hardware 52 may be discrete components within the
exemplary display device 40, or may be incorporated within the
processor 21 or other components.
[0057] The driver controller 29 takes the raw image data generated
by the processor 21 either directly from the processor 21 or from
the frame buffer 28 and reformats the raw image data appropriately
for high speed transmission to the array driver 22. Specifically,
the driver controller 29 reformats the raw image data into a data
flow having a raster-like format, such that it has a time order
suitable for scanning across the display array 30. Then the driver
controller 29 sends the formatted information to the array driver
22. Although a driver controller 29, such as a LCD controller, is
often associated with the system processor 21 as a stand-alone
Integrated Circuit (IC), such controllers may be implemented in
many ways. They may be embedded in the processor 21 as hardware,
embedded in the processor 21 as software, or fully integrated in
hardware with the array driver 22.
[0058] Typically, the array driver 22 receives the formatted
information from the driver controller 29 and reformats the video
data into a parallel set of waveforms that are applied many times
per second to the hundreds and sometimes thousands of leads coming
from the display's x-y matrix of pixels.
[0059] In one embodiment, the driver controller 29, array driver
22, and display array 30 are appropriate for any of the types of
displays described herein. For example, in one embodiment, driver
controller 29 is a conventional display controller or a bi-stable
display controller (e.g., an interferometric modulator controller).
In another embodiment, array driver 22 is a conventional driver or
a bi-stable display driver (e.g., an interferometric modulator
display). In one embodiment, a driver controller 29 is integrated
with the array driver 22. Such an embodiment is common in highly
integrated systems such as cellular phones, watches, and other
small area displays. In yet another embodiment, display array 30 is
a typical display array or a bi-stable display array (e.g., a
display including an array of interferometric modulators).
[0060] The input device 48 allows a user to control the operation
of the exemplary display device 40. In one embodiment, input device
48 includes a keypad, such as a QWERTY keyboard or a telephone
keypad, a button, a switch, a touch-sensitive screen, a pressure-
or heat-sensitive membrane. In one embodiment, the microphone 46 is
an input device for the exemplary display device 40. When the
microphone 46 is used to input data to the device, voice commands
may be provided by a user for controlling operations of the
exemplary display device 40.
[0061] Power supply 50 can include a variety of energy storage
devices as are well known in the art. For example, in one
embodiment, power supply 50 is a rechargeable battery, such as a
nickel-cadmium battery or a lithium ion battery. In another
embodiment, power supply 50 is a renewable energy source, a
capacitor, or a solar cell, including a plastic solar cell, and
solar-cell paint. In another embodiment, power supply 50 is
configured to receive power from a wall outlet.
[0062] In some implementations control programmability resides, as
described above, in a driver controller which can be located in
several places in the electronic display system. In some cases
control programmability resides in the array driver 22. The
above-described optimization may be implemented in any number of
hardware and/or software components and in various
configurations.
[0063] The details of the structure of interferometric modulators
that operate in accordance with the principles set forth above may
vary widely. For example, FIGS. 7A-7E illustrate five different
embodiments of the movable reflective layer 14 and its supporting
structures. FIG. 7A is a cross section of the embodiment of FIG. 1,
where a strip of metal material 14 is deposited on orthogonally
extending supports 18. In FIG. 7B, the moveable reflective layer 14
of each interferometric modulator is square or rectangular in shape
and attached to supports at the corners only, on tethers 32. In
FIG. 7C, the moveable reflective layer 14 is square or rectangular
in shape and suspended from a deformable layer 34, which may
comprise a flexible metal. The deformable layer 34 connects,
directly or indirectly, to the substrate 20 around the perimeter of
the deformable layer 34. These connections are herein referred to
as support posts. The embodiment illustrated in FIG. 7D has support
post plugs 42 upon which the deformable layer 34 rests. The movable
reflective layer 14 remains suspended over the gap, as in FIGS.
7A-7C, but the deformable layer 34 does not form the support posts
by filling holes between the deformable layer 34 and the optical
stack 16. Rather, the support posts are formed of a planarization
material, which is used to form support post plugs 42. The
embodiment illustrated in FIG. 7E is based on the embodiment shown
in FIG. 7D, but may also be adapted to work with any of the
embodiments illustrated in FIGS. 7A-7C as well as additional
embodiments not shown. In the embodiment shown in FIG. 7E, an extra
layer of metal or other conductive material has been used to form a
bus structure 44. This allows signal routing along the back of the
interferometric modulators, eliminating a number of electrodes that
may otherwise have had to be formed on the substrate 20.
[0064] In embodiments such as those shown in FIG. 7, the
interferometric modulators function as direct-view devices, in
which images are viewed from the front side of the transparent
substrate 20, the side opposite to that upon which the modulator is
arranged. In these embodiments, the reflective layer 14 optically
shields the portions of the interferometric modulator on the side
of the reflective layer opposite the substrate 20, including the
deformable layer 34. This allows the shielded areas to be
configured and operated upon without negatively affecting the image
quality. For example, such shielding allows the bus structure 44 in
FIG. 7E, which provides the ability to separate the optical
properties of the modulator from the electromechanical properties
of the modulator, such as addressing and the movements that result
from that addressing. This separable modulator architecture allows
the structural design and materials used for the electromechanical
aspects and the optical aspects of the modulator to be selected and
to function independently of each other. Moreover, the embodiments
shown in FIGS. 7C-7E have additional benefits deriving from the
decoupling of the optical properties of the reflective layer 14
from its mechanical properties, which are carried out by the
deformable layer 34. This allows the structural design and
materials used for the reflective layer 14 to be optimized with
respect to the optical properties, and the structural design and
materials used for the deformable layer 34 to be optimized with
respect to desired mechanical properties.
[0065] Light incident on an interferometric modulator is either
reflected or absorbed due to constructive or destructive
interference, depending on the distance between the optical stack
16 and the reflective layer 14. The perceived brightness and
quality of a display using interferometric modulators is dependent
on the light incident on the display, since that light is reflected
to produce an image in the display. In some circumstances, such as
in low ambient light conditions, an illumination system may be used
to illuminate the display to produce an image.
[0066] FIG. 8 is a cross section of a display device including an
illumination system that includes a light guide panel 80 disposed
adjacent a display 81. The light guide panel 80 includes a light
turning film 89 having light turning features 82. A light source 92
injects light into the panel 80. The light turning features 82
direct the light propagating through the light guide panel 80 onto
the display 81.
[0067] With reference to FIG. 9, it has been found that the light
turning features 82 are susceptible to light loss, which can reduce
the amount of light redirected to the display 81. The features 82
are formed by facets 82a and 82b, which form angles .theta..sub.1
and .theta..sub.2 of greater than 90.degree. with surfaces 83a,
83b, respectively. Typically, light incident the facet 82a is
reflected either towards a display 81 or may continue to propagate
inside the light guide panel 80 by total internal reflection.
However, light incident the facet 82a at close to the angle of the
normal to that surface is not reflected and can propagate out of
the light guide panel 80, thereby causing light loss. In display
light applications, this light loss can result in reduced display
brightness and/or uniformity.
[0068] With reference to FIG. 10A, some embodiments of the
invention provide slits 100 for redirecting light propagating
through a light guide body 180, which can be a panel of optically
transmissive material. Advantageously, the slits 100 reduce light
loss by recycling light that propagates out of the panel 180. For
example, the ray 103 propagates out of the panel 180, but is then
re-injected into the panel 180, where it continues to propagate
until redirected as desired out of the panel 180 by contact with a
facet 104.
[0069] It will be appreciated that the slits 100 are undercuts in
the light guide body 180 and are defined by facets 104 and 106. The
volume defined by the "undercut" extends at least partly directly
over the surface 108 of the light guide body 180, when the surface
108 is positioned facing downwards. In some embodiments, the facet
106 and the surface 108 are contiguous through and define an angle
110, which is less than 90.degree.. It will be appreciated that,
while devoid of the material forming the light guide body 180, the
slits 100 can be filled with another material that facilitates
total internal reflection in the body 180. In other embodiments,
the slits 100 can have an open volume and be completely devoid of
solid material.
[0070] The facets 104 are angled to redirect or reflect, in a
desired direction, light propagating through the panel 180. In some
embodiments, light is injected into the light guide body by the
light source 192, impinges on the facet 104 and is redirected
towards the display 81.
[0071] With reference to FIG. 10B, the slits 100 are lined with an
anti-reflective coating 112 in some embodiments. The
anti-reflective coating 112 has advantages for reducing undesired
light reflections. For example, for light exiting the facet 104,
the coating 112 can minimize the reflection of light off of the
facet 106, thereby facilitating the re-injection of light into the
panel 180. Examples of anti-reflective coatings include, without
limitation, silicon oxide (SiO.sub.2), silicon nitride (SiN.sub.4)
and aluminum oxide (Al.sub.2O.sub.3) coatings.
[0072] In some embodiments, the slits 100 form a volume that is
open to the surface 108. In some other embodiments, with reference
to FIG. 10C, the slits 100 can be disposed completely within the
light guide body 180. For example, the slits 100 can be formed
under the surface 108 and a narrow connecting part 114 at an end of
each slit 100 can be sealed, e.g., by the natural resiliency of the
material forming the panel 180, or by application of a sealant or
adhesive on those parts. The sealing of the parts 114 can reduce
contamination of or damage to the slits 100 by protecting against
external objects that may contact with the surfaces or edges of
facets 104 and 106 of the slits 100. In some other embodiments, the
narrow parts 114 are not sealed, but the opening defined by that
part is relatively narrow compared to the illustrated transverse
cross-sectional area of the slits 100, thereby also providing
protection for the slits 100.
[0073] It will be appreciated that the illustrated slits 100 are
not necessarily drawn to scale and their relative sizes can differ.
Moreover, the relative angles of the facets 104 and 106 can differ
from that illustrated. For example, the cross-sectional areas of
the slits 100 can vary and the relative orientations and angles
defined by the facets 104, 106 can vary from slit to slit.
[0074] With reference to FIGS. 10A-10C, in some embodiments, the
facets 104 and 106 can be substantially parallel opposite one
another, and can be joined by a single slit sidewall 105 that is
parallel to the surface 108. The slit 100 can thus define a volume
having the shape of a parallelogram. The parallel orientation of
the slit sidewall 105 advantageously facilitates total internal
reflection of light within the body 102, since the parallel
sidewall 105 reflects light at similar angles to the surface
108.
[0075] The slits 100 can be utilized in various devices in which
light turning, or redirection, is desired. In some embodiments, the
slits 100 are utilized as light turning features in illumination
devices. Such illumination devices can include wide area lights for
indoor or outdoor use. For example, illumination devices can
provide overhead lighting for rooms and other indoor spaces.
[0076] FIG. 11A is a top plan view of a display device having a
light guide body 180 and an illumination system including a light
bar 190 utilizing the slits 100 as light turning features. FIG. 11B
is a cross section of the display device. The light bar 190 and
light guide body 180 are formed of substantially optically
transmissive material that can support the propagation of light
through the lengths of those structures. For example, the light bar
190 and light guide body 180 can be formed of glass, plastic or
other highly transparent materials.
[0077] With reference to both FIGS. 11A and 11B, the light guide
body 180 is disposed adjacent and faces a display 181. The slits
100 are configured to turn light from the light bar 190 towards the
display 181. In some embodiments, the illumination system acts as a
front light. Light reflected from the display 181 is transmitted
back through and out of the light guide body 180 towards the
viewer. The display 181 can include various display elements, e.g.,
a plurality of spatial light modulators, interferometric
modulators, liquid crystal elements, electrophoretic, etc., which
can be arranged parallel the major surface of the panel 180. The
display 181 is the display 30 (FIGS. 6A and 6B) in some
embodiments.
[0078] With continued reference to FIG. 11A, the light bar 190 has
a first end 190a for receiving light from a light emitter 192. The
light bar 190 and the light emitter 192 together form a line light
source. The light emitter 192 may include a light emitting diode
(LED), although other light emitting devices are also possible.
Light emitted from the light emitter 192 propagates into the light
bar 190. The light is guided therein, for example, via total
internal reflection at sidewalls thereof, which form interfaces
with air or some other surrounding fluid or solid medium. For
example, where the light bar 190 is formed of a material with a
similar refractive index as the light guide body 180, the light bar
190 can be separated from the light guide body 180 by air, fluid or
solid medium to promote total internal reflection within the light
bar 190.
[0079] The light bar 190 includes slits 100 on at least one side,
for example, the side 190b that is substantially opposite the light
guide body 180. The slits 100 are configured to turn light incident
on that side 190b of the light bar 190 and to direct that light out
of the light bar 190 (e.g., out side 190c) into the light guide
body 180. It will be appreciated that the slits 100 shown in FIG.
11A are schematic. The sizes, shapes, densities, position, etc. of
the slits 100 can vary from that depicted to achieve the desired
light turning effect. For example, in some embodiments, the slits
100 extend further into the body of the light bar 190 with
increasing distance from the side 190a.
[0080] In certain embodiments, the illumination apparatus further
includes a coupling optic (not shown) between the light bar 190 and
the light guide body 180. For example, the coupling optic may
collimate, magnify, diffuse, change the color, etc., of light
propagating from the light bar 190.
[0081] Accordingly, light travels from the first end 190a in the
direction of a second end 190d of the light bar 190, and can be
reflected back again towards the first end 190a. Along the way, the
light impinging on the slits 100 is turned towards the adjacent
light guide body 180. The light guide body 180 is disposed with
respect to the light bar 190 so as to receive light that has been
turned by the slits. The light guide body 180, in turn, redirects
light out of the light guide body 180 and towards the display
181.
[0082] While shown for ease of discussion and illustration on one
side of the light bar 190 (FIG. 11A), in some embodiments, the
slits 100 are formed along multiple surfaces of the light bar 190.
With reference to FIG. 11C, the slits 100 are formed along the
sides 190b and 190c of the light bar 190. Forming slits 100 on
multiple sides can have advantages for more efficiently turning
light, per unit length of the light bar 190. In addition, the
spacing between slits 100 on each side 190b, 190c can be increased
for a given density of the slits 100 per unit length of the light
bar 190, which can have advantages for facilitating the
manufacturing of dense slit patterns. It will be appreciated that
the slits in the surfaces 108 and 109 can differ in one or more of
total number, transverse cross-sectional shape, dimensions, and
angles formed between the slits and the major surfaces.
[0083] With reference to FIG. 11D, a light bar such as the light
bar 190 can be integrated into a light guide body, thereby forming
a single light guide body/light bar structure 182. The integrated
light guide body/light bar structure 182 has advantages for
manufacturing and for reducing the number of components in a
display device. It will be appreciated that the light turning
features can take various forms, including prismatic features such
as the slits 100 (as discussed further herein), holographic
features, or various other light turning features known in the
art.
[0084] It will be appreciated that the light guide body 182 or 180
(FIGS. 10A-11C) is defined by first and second opposite edges. As
illustrated, the slits 100 may be formed in one of these edges and
redirect light in a direction towards the opposite edge. Third and
fourth edges further define the light guide body 182, with light
entering into the light guide body by impinging, e.g., the third
edge (the lower edge in FIG. 11E). The light guide body 182 also
contains upper and lower major sides or surfaces (stretching from
the first to the second edge and from the third to the fourth
edge).
[0085] Light is injected into the light guide body 182 from the
light emitter 192. The light can be collimated and is redirected by
the slits 100 towards the display area 183, where light turning
features redirect the light towards a display (not shown).
[0086] With continued reference to FIG. 11D, slits 100 closer to
the light emitter 192 can block light from reaching the surfaces of
other slits 100 farther from the light emitter 192. With increasing
distance from the light emitter 192 along the Y-axis, the slits 100
extend further along the X-axis, to allow contact with light from
the light emitter 192. In some embodiments, the slits 100 farthest
from the light emitter 192 can span substantially the entire length
of the emitter 192 along the X-axis.
[0087] It will be appreciated that the pitch or density of the
slits 100 along the Y-axis, the length of the slits 100 along the
X-axis and the angles of the slits can be uniform or can vary to
achieve a desired light turning effect. For example, in some
embodiments, the exposed surface area of the slits 100 for
contacting and turning light are substantially equal per unit
length along the Y-axis, thereby facilitating a uniform flux of
turned light per unit length along the Y-axis.
[0088] To further increase the efficiency of the light extraction
(i.e., to increase the proportion of the emitted light that is
turned towards the display area 183), light from the light emitter
192 is angled towards an edge 184 of the illustrated light guide
body 182, along which the slits 100 are formed. The light can be
angled by, e.g., attaching the light emitter 192 to the light guide
body 182 at an angle, or by use of an appropriate optical component
or film to direct the light in the desired direction.
Advantageously, the light that is not turned can be recycled,
thereby increasing the efficiency of the light extraction relative
to arrangements in which the light is not directed along the edge
in which the slits 100 are formed.
[0089] With reference to FIG. 11E, as noted above, in some
embodiments, additional slits 100 are provided in an area 182
corresponding to a display. Light is emitted from the light emitter
192, the light is then turned by the slits 100 on the edge 184, and
the turned light is turned towards a display (not shown) by the
slits 100 in the display area 182.
[0090] In some other embodiments, the slits 100 can be provided in
a light guide body without slits 100 that form the light turning
features of a light bar. FIG. 12A shows a cross section of a
display device including a light guide body 180 having slits 100.
The light bar 190 injects light into a first end 180a of the light
guide body 180. The light travels from the first end 180a in the
direction of a second end 180d of the light guide body 180, and can
be reflected back again towards the first end 180a by total
internal reflection. As it propagates through the light guide body
180, some of the light impinges on the slits 100 and is turned
towards the display 181.
[0091] With continued reference to FIG. 12A, the slits 100 are
formed along the major side or surface 180b, which faces the
display 181. In some other embodiments, with reference to FIG. 12B,
the slits 100 can be disposed along both major surfaces of the
light guide body 180, e.g., along both major sides 180b and 180c.
As noted above, forming slits 100 along multiple surfaces can have
advantages for efficiently turning light and for ease of
manufacture, where a high density of slits is desired for a unit
length of the light guide body 180. While shown separated from the
end 180a in the FIGS. 12A and 12B for ease of illustration, it will
be appreciated that the light bar 190 can form an integrated
structure with the light guide body 180, or can be separated. For
example, the light bar 190 of FIGS. 12A and 12B can form a unitary
light guide body, with slits in the light bar 190 and a major
surface of the light guide body.
[0092] The slits 100 can be distributed in the light bar 190, the
light turning light guide body 180 and the integrated light guide
body/light bar structure 182 in various patterns to achieved
desired light turning properties. It will be appreciated that
uniformity of power per area is desired in many applications to
uniformly light the display 181 (FIGS. 11B, 12A and 12B). The slits
100 may be arranged to achieve good uniformity in power per
area.
[0093] With reference to FIGS. 13A, 13B and 13C, the density of the
slits 100 increases with increasing distance from the light bar 190
(FIG. 13A), the point light emitter 192 (FIG. 13B) or the edge 184
(FIG. 13C). With reference to FIG. 13A, the number of slits 100 per
unit area (in one or both of the top and bottom major sides of the
light guide body 180) increases with increasing distance from the
edge of the light guide body 180 directly adjacent the light bar
190. The slits 100 extend in substantially straight lights parallel
to the light bar 190.
[0094] With reference to FIG. 13B, the number of slits 100 per unit
area (in one or both of the top and bottom major sides of the light
guide body 180) increases with distance from the point light source
192. The slits 100 for semicircular segments centered on the point
light source 192.
[0095] With reference to FIG. 13C, the number of slits 100 per unit
area (in one or both of the top and bottom major sides of the light
guide body 180) increases with distance from the edge 184. The
additional slits 100 along that edge turn light and allow that side
of the light guide body 182 to function as a line light source.
[0096] In some embodiments, the varying density of the slits 100
allows the flux of light redirected per unit area to be highly
uniform over the area of the light turning light guide body 180,
182 corresponding to the display 181. As light propagates through
the light turning light guide body 180, 182, some amount of light
contacts the slits 100 and is redirected out of the light guide
body 180, 182. Thus, the remaining light propagating through the
light guide body 180, 182 decreases with distance from the light
source, as more and more light is redirected by contact with the
slits 100. To compensate for the decreasing amounts of light
propagating through the light guide body 180, 182, the density of
the slits 100 increases with distance from a light point source or
line light source.
[0097] It will be appreciated that the density of the slits refers
to the area occupied by the slits 100 per unit area of a body of
material in which the slits are formed. A single large slit 100 or
a plurality of smaller slits 100 in a given area may have the same
density. Thus, the density may be changed due to, e.g., changes in
the sizes and/or numbers of the slits 100 per area.
[0098] The slits 100 can be formed by various methods. In some
embodiments, the slits 100 are formed as a body of light
propagating material, such as a light guide body or light bar, is
formed. For example, the body of light propagating material can be
formed by extrusion through a die having an opening corresponding
to a cross-sectional shape of a light guide body or light bar and
also having projections in the die corresponding to the slits 100.
The material forming the body is pushed and/or drawn through the
die in the direction in which the slits 100 extend, thereby forming
a length of material having the desired cross-sectional shape and
having the slits 100. The length of material is then cut into the
desired dimensions for a light guide body or light bar.
[0099] In another example, the body of light propagating material
can be formed by casting, in which material is placed in a mold and
allowed to harden. The mold contains extensions corresponding to
the slits. Once hardened, the body of light propagating material is
removed from the mold. The mold can correspond to a single light
guide body or light bar, such that the removed body of light
propagating material can be used as a single light turning light
guide body or light bar. In other embodiments, the mold produces a
large sheet of material, which is cut into desired dimensions for
one or more light turning light guide bodys and/or light bars.
[0100] In yet another example, the body of light propagating
material is formed by injection molding, in which a fluid material
is injected into a mold and then ejected from the mold after
hardening. Where the mold corresponds to a single light guide body
or light bar, the removed body of light propagating material can be
used as a single light turning light guide body or light bar. The
mold may also produce a large sheet of material, and the sheet is
cut into desired dimensions for one or more light turning light
guide bodys and/or light bars.
[0101] In some other embodiments, the slits 100 are formed after
formation of a light turning body. For example, the slits 100 can
be formed by embossing, in which a die, having protrusions
corresponding to the slits 100, is pressed against a body of light
propagating material to form the slits 100 in the body. The body
can be heated, making the body sufficiently malleable to take the
shape of the slits 100.
[0102] In another example, material is removed from the body of
light propagating material to form the slits 100. For example, the
slits 100 can be formed by machining or cutting into the body. In
other embodiments, material is removed from the body by laser
ablation.
[0103] It will be appreciated that the methods disclosed herein can
be utilized to form light bars and/or light guide bodys. In some
embodiments, the light bars can be formed after formation of the
light guide body. For example, after forming a sheet of material
having slits (e.g., by extrusion, casting, injection molding, or
removal of material from a body of light propagating material), the
sheet of material can be cut or stamped into a desired shape. In
this cutting or stamping process, slits 100 can be formed at an
edge of a light guide body.
[0104] In some other embodiments, a light guide body is formed in
sections that are later combined. The sections can be formed using
the methods disclosed herein. The sections are glued or otherwise
attached together with a refractive index matching material to form
a single light guide body. Section by section formation of a light
guide body allows the formation of curved slits 100 that may
otherwise be difficult for a particular method to form as a single
continuous structure.
[0105] In some embodiments, the light guide body is attached to a
display after being formed. The light guide body is also attached
to a light source to form a display device having an illumination
system.
[0106] It will be understood by those skilled in the art that,
although this invention has been disclosed in the context of
certain preferred embodiments and examples, the present invention
extends beyond the specifically disclosed embodiments to other
alternative embodiments and/or uses of the invention and obvious
modifications and equivalents thereof. In addition, while several
variations of the invention have been shown and described in
detail, other modifications, which are within the scope of this
invention, will be readily apparent to those of skill in the art
based upon this disclosure. It is also contemplated that various
combinations or sub-combinations of the specific features and
aspects of the embodiments may be made and still fall within the
scope of the invention. It should be understood that various
features and aspects of the disclosed embodiments can be combined
with, or substituted for, one another in order to form varying
modes of the disclosed invention. Thus, it is intended that the
scope of the present invention herein disclosed should not be
limited by the particular disclosed embodiments described above,
but should be determined only by the claims that follow.
* * * * *