U.S. patent application number 15/522423 was filed with the patent office on 2017-11-23 for manufacture of optical light guides.
The applicant listed for this patent is Heptagon Micro Optics Pte. Ltd.. Invention is credited to Markus ROSSI, Hartmut RUDMANN, Nicola SPRING.
Application Number | 20170336543 15/522423 |
Document ID | / |
Family ID | 55954738 |
Filed Date | 2017-11-23 |
United States Patent
Application |
20170336543 |
Kind Code |
A1 |
SPRING; Nicola ; et
al. |
November 23, 2017 |
MANUFACTURE OF OPTICAL LIGHT GUIDES
Abstract
The method for manufacturing optical light guide elements
comprises a) providing a plurality of initial bars, each initial
bar extending along a respective initial-bar direction from a first
bar end to a second bar end and having a first side face extending
from the first bar end to the second bar end, the first side face
being reflective; b) positioning the initial bars in a row with
their respective initial-bar directions aligned parallel to each
other and with their respective first surfaces facing towards a
neighboring one of the initial bars; c) fixing the plurality of
initial bars with respect to each other in the position achieved in
step b) to obtain a bar arrangement. The method further comprises
at least one of the following steps d), d'), d''): d) segmenting
the bar arrangement into bars referred to as prism bars each of
which comprises a portion of at least two different ones of the
plurality of initial bars, by conducting a plurality of cuts
through the bar arrangement; in particular wherein the cuts are
parallel cuts; d') segmenting the bar arrangement into bars
referred to as prism bars by separating the bar arrangement into
parts along cut lines, wherein the cut lines are at an angle with
the initial-bar directions; d'') segmenting the bar arrangement
into bars referred to as prism bars by separating the bar
arrangement into sections by creating cut faces which are at an
angle with respect to the initial-bar directions. And the method
further comprises e) segmenting the prism bars into parts.
Inventors: |
SPRING; Nicola;
(Ziegelbrucke, CH) ; RUDMANN; Hartmut; (Jona,
CH) ; ROSSI; Markus; (Jona, CH) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Heptagon Micro Optics Pte. Ltd. |
Singapore |
|
SG |
|
|
Family ID: |
55954738 |
Appl. No.: |
15/522423 |
Filed: |
November 11, 2015 |
PCT Filed: |
November 11, 2015 |
PCT NO: |
PCT/SG2015/050443 |
371 Date: |
April 27, 2017 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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62211436 |
Aug 28, 2015 |
|
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|
62160224 |
May 12, 2015 |
|
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62079080 |
Nov 13, 2014 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G02B 17/0856 20130101;
G02B 5/045 20130101; G02B 5/04 20130101; G02B 6/43 20130101; F21V
7/0091 20130101; G02B 3/0062 20130101; G02B 6/13 20130101; G02B
13/0065 20130101 |
International
Class: |
G02B 5/04 20060101
G02B005/04; F21V 7/00 20060101 F21V007/00; G02B 17/08 20060101
G02B017/08 |
Claims
1. A method for manufacturing optical light guide elements, the
method comprising a) providing a plurality of bars referred to as
initial bars, each initial bar extending along a respective
initial-bar direction from a first bar end to a second bar end and
having a first side face extending from the first bar end to the
second bar end, the first side face being reflective; b)
positioning the initial bars in a row with their respective
initial-bar directions aligned parallel to each other and with
their respective first surfaces facing towards a neighboring one of
the initial bars; c) fixing the plurality of initial bars with
respect to each other in the position achieved in step b) to obtain
a bar arrangement; the method further comprising at least one of
steps d), d'), d''): d) segmenting the bar arrangement into bars
referred to as prism bars each of which comprises a portion of at
least two different ones of the plurality of initial bars, by
conducting a plurality of cuts through the bar arrangement; in
particular wherein the cuts are parallel cuts; d') segmenting the
bar arrangement into bars referred to as prism bars by separating
the bar arrangement into parts along cut lines, wherein the cut
lines are at an angle with the initial-bar directions; d'')
segmenting the bar arrangement into bars referred to as prism bars
by separating the bar arrangement into sections by creating cut
faces which are at an angle with respect to the initial-bar
directions; the method further comprising e) segmenting the prism
bars into parts.
2. The method according to claim 1, wherein at least one of each of
the parts is be comprised in one of the optical light guide
elements; each of the parts comprises one of the optical light
guide elements.
3. The method according to claim 1 or claim 2, wherein each of the
first side faces comprises a first reflective coating; in
particular wherein each of the initial bars has a third side face
extending from the first bar end to the second bar end, wherein
each of the third side faces comprises a third reflective
coating.
4. The method according to claim 1 or claim 2, wherein each of the
first side faces is reflective due to total internal
reflection.
5. The method according to one of claims 1 to 4, wherein, in step
b), the initial bars are positioned in a distance to each
other.
6. The method according to one of claims 1 to 5, wherein each of
the initial bars has a first, a second, a third and a fourth side
faces, each extending from the first to the second bar end, the
first and second side faces being planar faces aligned parallel to
each other, the third and fourth side faces being separated from
each other by and arranged between the first and the second side
faces, in particular wherein the third side face is reflective.
7. The method according to one of claims 1 to 6, comprising
providing a plate having an upper face and a lower face which are
aligned parallel to each other, in particular wherein the upper
face and/or the lower face is reflective; obtaining the plurality
of initial bars by conducting a plurality of cuts through the plate
which run parallel to each other and parallel to the initial-bar
directions and which create cut faces which are aligned
perpendicularly to the upper and lower faces.
8. The method according to one of claims 1 to 7, comprising a*)
providing a plurality of bars referred to as further bars, each
further bar extending along a respective further-bar direction from
a first further bar end to a second further bar end; b*)
positioning, in step b), each of the further bars between two
neighboring ones of the initial bars with their respective
further-bar direction aligned parallel to the initial-bar
directions; c*) fixing, in step c), the plurality of further bars
with respect to each other and with respect to the initial bars in
the position achieved in step b) to obtain the bar arrangement.
9. The method according to claim 8, comprising providing a plate
referred to as further plate having an upper face and a lower face
which are aligned parallel to each other, in particular wherein the
upper face and/or the lower face is reflective; obtaining the
plurality of further bars by conducting a plurality of cuts through
the further plate which run parallel to each other and parallel to
the further-bar directions and which create cut faces which are
aligned perpendicularly to the upper and lower faces.
10. The method according to one of claims 1 to 9, comprising
accomplishing the positioning mentioned in step b) by the aid of a
jig, in particular comprising holding the initial bars in the
jig.
11. The method according to one of claims 1 to 10, wherein the
fixing mentioned in step c) comprises attaching a first substrate
to the each of the initial bars, in particular wherein the fixing
mentioned in step c) comprises, in addition, attaching a second
substrate to the each of the initial bars to sandwich the initial
bars between the first and second substrates.
12. The method according to one of claims 1 to 11, wherein the cut
lines mentioned in steps d') and d'') and the cuts mentioned in
step d), respectively, are at an angle of between 20.degree. and
75.degree. with respect to the initial bar directions, more
particularly at an angle of 45.degree. with respect to the initial
bar directions.
13. The method according to one of claims 1 to 12, comprising,
before step e), attaching the prism bars to one or more further
substrates, wherein the segmenting mentioned in step e) comprises
segmenting the one or more further substrates, in particular
wherein each of the at least two parts comprises a section of the
one or more further substrates, e.g., a section of each of two
further substrates.
14. The method according to claim 13, wherein each of the one or
more further substrates comprises a wafer on which a plurality of
lens elements are present, in particular wherein each of said parts
comprises at least one of the lens elements.
15. An optical light guide element for guiding light incident on
the optical light guide element along an incidence direction and
exiting the optical light guide element along an exit direction
inside the optical light guide element between two reflective faces
of the optical light guide element referred to as first and second
reflective faces along a main direction of the optical light guide
element, wherein the main direction is at an angle with the
incidence direction and at an angle with the exit direction, the
optical light guide element comprising two mutually parallel outer
side panels referred to as first and third outer side panels, the
main direction being aligned parallel to the first and third outer
side panels; a first prism comprising two base faces aligned
parallel to the first and third outer side panels, one attached to
the first outer side panel, the other attached to the third outer
side panel; wherein the first prism comprises, located between the
first and third outer side panels, the first reflective face shaped
and aligned for redirecting light incident on the optical light
guide element along the incidence direction into the main
direction, and wherein the optical light guide element comprises,
located between the first and third outer side panels, a second
reflective face shaped and aligned for redirecting light redirected
by the first reflective face into the main direction to exit the
optical light guide element along the exit direction, wherein the
second reflective face is comprised in the first prism; or
comprised in a second prism of the optical light guide element, the
second prism comprising two further base faces aligned parallel to
the first and third outer side panels, one attached to the first
outer side panel, the other attached to the third outer side panel,
wherein the second prism comprises, between the two further base
faces, the second reflective face.
Description
[0001] The invention relates to optical light guide elements and,
more specifically, to their manufacture. More particularly, it
relates to miniaturized optical light guide elements, e.g., for use
in electronic devices such as smart phones and other portable
computing devices such as portable computers, tablet computers. And
it relates to corresponding electronic devices containing optical
light guide elements. In particular, the invention relates to the
manufacture of (miniaturized) optical light guide elements taking
place, at least in part, on wafer-level.
[0002] One object of the invention is to create a way of
manufacturing high-precision optical light guide elements.
[0003] Another object of the invention is to create a way of
manufacturing optical light guide elements in high volumes (mass
production).
[0004] Further objects and various advantages emerge from the
description and embodiments below.
[0005] At least one of these objects is at least partially achieved
by devices and methods according to the patent claims.
[0006] In a first aspect, which is quite specific, the invention
can be described, e.g., by the following method:
[0007] A method for manufacturing optical light guide elements, the
method comprising [0008] A) providing a plate having a reflective
upper face and a reflective lower face which are aligned parallel
to each other; [0009] B) obtaining a plurality of bars referred to
as initial bars, each of which is extended along a respective
initial-bar direction, by conducting a plurality of cuts through
the plate which run parallel to each other and parallel to the
initial-bar directions and which create cut faces which are aligned
perpendicularly to the upper and lower faces; [0010] C) positioning
the initial bars at a distance to each other in a row, with their
bar directions aligned parallel to each other and with a first one
of the cut faces of each of the initial bars lying in a first plane
and a second one of the cut faces of each of the initial bars lying
in a second plane; [0011] D) obtaining a bar arrangement by
attaching a first substrate to the each of the first cut faces and
attaching a second substrate to the each of the second cut faces;
[0012] E) obtaining a plurality of bars referred to as prism bars
each of which comprises a portion of at least two different ones of
the plurality of initial bars, by conducting a plurality of
parallel cuts through the bar arrangement; [0013] F) segmenting
each of the prism bars into at least two parts.
[0014] The described method can make possible a high-volume
production of miniaturized optical light guide elements of high
optical precision. A mutual alignment of reflective faces of
optical light guide elements may this way be accomplished with very
high precision. And the manufacturing method can make possible to
manufacture optical light guide elements in which a distance
between reflective faces of optical light guide elements
contributing to an optical path length inside the optical light
guide element is defined with very high precision.
[0015] In one embodiment, the plate is coated with a reflective
coating, so as to achieve a desired reflectivity.
[0016] The coating may comprise a metal coating.
[0017] The coating may be comprise a dielectric coating.
[0018] The coating may be a multilayer coating, e.g., comprising,
in addition to a reflective layer, a protective layer.
[0019] In one embodiment, the plate is polished (before and/or
after applying an optional coating).
[0020] In one embodiment, each of the cuts mentioned in step C) are
accomplished by means of one of [0021] dicing; [0022] laser
cutting; [0023] laser-scribing and subsequent breaking-apart.
[0024] In case of dicing, it may be provided that several passes of
a dicing blade employed are conducted. This may reduce stresses in
the initial bars.
[0025] Steps A) and B) mainly describe a very efficient way of
obtaining the initial bars.
[0026] The initial bars may be congeneric initial bars. At least,
they will usually have the same height (inherited from the plate)
and width (from an equidistant cutting).
[0027] In some embodiments, the initial bars are (and optionally
also the plate is) at least in part made of a non-transparent
dielectric material. E.g., the initial bars (and optionally also
the plate) can comprise at least one electrically conductive via
for establishing an electrical connection through the
non-transparent dielectric material across the respective initial
bar (and plate, respectively).
[0028] The non-transparent dielectric material may be, e.g., a
polymer-based material.
[0029] The non-transparent dielectric material may be a fiber
reinforced material.
[0030] For example, the non-transparent dielectric material may be
a printed circuit board base material, such as FR4/G10 or
polyimide.
[0031] Each of the initial bars (and optionally also the plate) can
be at least in part constituted by a section of a printed circuit
board.
[0032] Accordingly, also the prism bars can inherit these
properties from the initial bars.
[0033] The positioning described in step C) may be understood as a
rotation by 90.degree. of each of the initial bars about the
respective initial-bar direction and providing a separation between
neighboring ones in a direction perpendicular to the initial-bar
directions. However, this does not exclude a mutual shifting of
neighboring initial bars in a direction parallel to the initial-bar
directions.
[0034] As is clear from the above, however, it will be provided
that the first plane and the second plane are usually aligned
parallel to each other.
[0035] In one embodiment, two or more plates having a reflective
upper face and a reflective lower face which are aligned parallel
to each other are stacked upon each other, wherein the cuts
mentioned in step B) are conducted through the stack. This can make
the production of the initial bars more efficient. A removable
bonding material can be applied between neighboring plates in the
stack.
[0036] In one embodiment, the positioning mentioned in step C) is
accomplished by means of a jig. In particular, the initial bars may
be held in the jig. Usually, the initial bars are removed from the
jig before step E) is accomplished, i.e. before the cuts for
producing the prism bars are conducted.
[0037] The jig may have one protrusion per initial bar on which the
respective initial bar is positioned each, e.g., the respective
second cut face facing a top of the respective protrusion. Spacers
may be inserted then between neighboring initial bars for ensuring
an equidistant positioning of the initial bars in a direction
perpendicular to the initial bar directions.
[0038] Or the jig may have one groove per initial bar in which one
initial bar is inserted each, e.g., the respective second cut face
directed into the respective groove.
[0039] In one embodiment, the initial bars are held in the jig
during the attaching of the first substrate mentioned in step D).
It may, more specifically, be provided then, that the jig is
removed from the assembly comprising the initial bars and the first
substrate, before the second substrate is attached to the initial
bars.
[0040] In step D), a mutual positioning of the initial bars is
fixed by means of the first and second substrates. Accordingly,
such a bar arrangement can also be considered a sandwich wafer or a
wafer stack. Although the provision of the two substrates may
contribute to making possible the manufacture of hermetically
closed light guides (which usually have, e.g., an increased
lifetime and/or an increased reliability), it is also possible to
dispense with one or both of the substrates, cf. also below (second
aspect of the invention).
[0041] In one embodiment, step D) comprises applying a bonding
material, such as a glue, a curable epoxy or the like, to one or
both of [0042] the first substrate; [0043] each of the first cut
faces; and to one or both of [0044] the second substrate; [0045]
each of the second cut faces.
[0046] The application of the bonding material may be accomplished,
e.g., using a dispenser (and a needle of the dispenser), or by
means of screen printing.
[0047] The bonding material may comprise a multitude of solid balls
having a common diameter in addition to a liquid or viscous
hardenable (e.g., curable) material. This can make possible to
achieve very precisely defined distances between parts attached to
each other.
[0048] The first and second substrates may be transparent or
non-transparent. Non-transparency may decrease in a simple way a
sensitivity of the light guide element to undesired external
light.
[0049] In some embodiments, at least one of the first and second
substrates is at least in part made of a non-transparent dielectric
material. E.g., the first and/or second substrates can comprise at
least one electrically conductive via for establishing an
electrical connection through the non-transparent dielectric
material across the respective substrate.
[0050] The non-transparent dielectric material may be, e.g., a
polymer-based material.
[0051] The non-transparent dielectric material may be a fiber
reinforced material.
[0052] For example, the non-transparent dielectric material may be
a printed circuit board base material, such as FR4/G10 or
polyimide.
[0053] The first substrate and/or the second substrate can be at
least in part constituted by a section of a printed circuit
board.
[0054] Accordingly, also the prism bars can inherit these
properties from the initial bars.
[0055] At the end of step D) and at the beginning of and during
step E), the initial bars have to remain in their relative
positions with high precision.
[0056] Step E) is a particularly astute step. In step E), new bars,
namely the prism bars, are produced, which have angled or tilted
reflective faces, as they are desired in typical optical light
guide elements. This may in particular be achieved by cutting at an
angle with respect to the initial-bar directions, more particularly
such that the cuts are at an angle of 45.degree..+-.10.degree. with
respect to the initial bar directions. The angle can be
45.degree..+-.5.degree., e.g., 45.degree..
[0057] Usually, it will be provided that in step E), the parallel
cuts are creating cut faces which are aligned perpendicularly to
the first and second planes. However, in general, differently
aligned cut faces may be produced.
[0058] Defining that each of the prism bars is extended along a
prism-bar direction, wherein the prism-bar directions are (during
the conducting the cuts mentioned in step E)) parallel to the cuts,
the prism-bar directions are at an angle (e.g., of
45.degree..+-.10.degree. or of 45.degree.) with the initial-bar
directions.
[0059] The prism-bar directions usually correspond to a main
direction of light propagation in a finally produced optical light
guide element.
[0060] In one embodiment, the prism-bar directions are at an angle
of 45.degree..+-.10.degree. with the initial-bar directions, or at
45.degree..+-.5.degree..degree. with the initial-bar directions, or
at 45.degree. with the initial-bar directions. This can be
particularly useful for typical optical light guide elements,
namely for optical light guide elements receiving light from a
direction of incidence and emitting light in an output direction
which is parallel to the direction of incidence, wherein a main
direction of light propagtion in the optical light guide element is
perpendicular to both, the direction of incidence and the output
direction, and the direction of incidence, the output direction and
the main direction are in a common plane.
[0061] Of course, for other optical light guide elements, other
angles, in particular angles between 20.degree. and 75.degree., may
be used.
[0062] It is thus also possible to replace step E) by the following
step E'): [0063] E') obtaining a plurality of bars referred to as
prism bars, each of which is extended along a prism-bar direction,
by conducting a plurality of parallel cuts through the bar
arrangement (e.g., through the sandwich wafer) running parallel to
the prism-bar directions, the prism-bar directions being at an
angle with the initial-bar directions.
[0064] The angle can amount to 45.degree..+-.10.degree..
[0065] The angle can amount to 45.degree..+-.5.degree..
[0066] The angle can amount to 45.degree..
[0067] (In the following, step E') will typically not be mentioned
separately--even though it may apply, as it may replace step
E).)
[0068] In one embodiment, the method comprises, between step E) and
step F), polishing the cut faces produced by conducting the
plurality of parallel cuts described in step E) (or in step E')).
This makes possible to thin the prism bars; and it can make
possible to achieve a highly precise height of the prism bars, in
particular superior to a precision achievable using typical dicing
saws. In a typical optical light guide geometry, said height
finally influences a height of a finally produced optical light
guide element in a direction perpendicular to the main direction of
light propagation in the optical light guide element within a plane
containing the directions of incident and of outputted light of the
optical light guide element.
[0069] For producing a single optical light guide element, it is
usually sufficient to provide no more than two reflective surfaces.
Accordingly, for the manufacture of one (single) optical light
guide element, only a portion of a prism bar is needed.
Accordingly, in step F), the prism bars are segmented into
parts.
[0070] It is usually provided that at least one of, typically all
of: [0071] each of the parts obtained in step F) constitutes an
optical light guide element; or each of the parts constitutes a
portion of an optical light guide element; [0072] each of the
optical light guide elements comprises one of said parts; [0073]
each of the parts has an extension along the prism-bar direction
smaller than an extension along the prism-bar direction of the
respective prism bar; [0074] each of the parts comprising a portion
of at least two different ones of the plurality of initial
bars.
[0075] The segmenting mentioned in step F) typically comprises
conducting one or more segmenting steps (e.g., dicing steps) along
a cutting line aligned perpendicular to the prism-bar
directions.
[0076] In one embodiment, the segmenting mentioned in step F)
comprises at least one of [0077] at least one dicing step, e.g.,
using a wafer saw; [0078] at least one laser cutting step;
typically a plurality of dicing steps and/or a plurality of laser
cutting steps.
[0079] For contributing to achieving an hermetically closed optical
light guide element and/or for producing an optical light guide
element with increased functionality, another step can be inserted
between steps E) and F), namely a step in which at least one
further substrate (typically two further substrates) is applied to
the prism bars. Or rather, the prism bars are attached to at least
one further substrate. Accordingly:
[0080] In one embodiment, the prism bars are attached to one or
more further substrates before step F) is carried out, and by the
segmenting mentioned in step F), also the one or more further
substrates are segmented, wherein each of the at least two parts
comprises a section of the one or more further substrates, e.g., of
both further substrates.
[0081] Therein, it may be provided that the one or more further
substrates comprise (or rather are) one or more wafers on which a
plurality of lens elements are present. Each part, in this case,
usually comprises at least one of the lens elements.
[0082] In some embodiments, at least one of the one or more further
substrates is at least in part made of a non-transparent dielectric
material. E.g., one or two further substrates can comprise at least
one electrically conductive via for establishing an electrical
connection through the non-transparent dielectric material across
the respective further substrate.
[0083] The non-transparent dielectric material may be, e.g., a
polymer-based material.
[0084] The non-transparent dielectric material may be a fiber
reinforced material.
[0085] For example, the non-transparent dielectric material may be
a printed circuit board base material, such as FR4/G10 or
polyimide.
[0086] At least one of the further substrates can be at least in
part constituted by a section of a printed circuit board.
[0087] Accordingly, also the parts (cf. step F) can inherit these
properties from the one or more further substrates.
[0088] The presence of non-transparent material does, for example,
not exclude the presence of lenses which are to be traversed by
light guided by the respective light guide element.
[0089] For example, one or more transparent portions may be
provided in a respective further substrate adjacent to and possibly
surrounded by the non-transparent dielectric material so as to
provide one or more defined areas for light passing through the
respective further substrate. It this noted that this can apply,
not only to further substrates, but also (additionally or
alternatively) to the first substrates, the second substrates,
and/or to the prism bars, the initial bars, the plate.
[0090] The one or more further substrates are typically attached to
the prism bars at one or more cut faces produced by conducting the
plurality of parallel cuts described in step E).
[0091] Thus, in a typical embodiment, after attachment of two
further substrates, two opposite side walls of the prism bars (and
of the finally manufactured optical light guide elements) are
constituted by the first and second substrates (or rather, by
sections thereof), respectively, and these two opposite side walls
are separated from each other by further two opposite side walls of
the prism bars (and of the finally manufactured optical light guide
elements) which are constituted by one of the further substrates
each (or rather, by sections thereof). The mentioned two opposite
side walls are typically aligned perpendicularly to the mentioned
further two opposite side walls.
[0092] By means of the lens elements, light incident on a
manufactured optical light guide element and/or light outputted by
the optical light guide element can be influenced, e.g.,
focused.
[0093] Even though it is usually more efficient to attach a
plurality of prism bars to one and the same further substrate, it
is generally also possible to attach no more than only one prism
bar to one and the same further substrate.
[0094] In case one or more further substrates are provided as
described above, the segmenting mentioned in step F) typically
comprises conducting one or more segmenting steps (e.g., dicing
steps) along a cutting line aligned parallel to the prism-bar
directions. By these segmenting steps, at least the one or more
further substrates are cut. Optionally, also the prism bars are cut
thereby.
[0095] At least two different types of finally manufactured optical
light guide elements, namely a type I and a type II, may be
obtained by the described method. By selecting the location of cut
lines at which the segmentation mentioned in step F) is
accomplished, it can be defined whether type I and/or type II
optical light guide elements are produced.
[0096] Light propagating in an optical light guide element along
the main direction between two reflective faces of the optical
light guide element (the two reflective faces can, e.g., originate
from the upper and lower face of the plate, respectively)
propagates [0097] for a type I optical light guide element: in a
transparent solid material of an initial bar (and thus in a
transparent solid material of the plate present between the upper
and lower face of the plate); and [0098] for a type II optical
light guide element: in vacuum or in a gas present between the two
reflective faces of the optical light guide element (i.e. in a
cavity of the optical light guide element).
[0099] Accordingly, said light propagation takes place, in case of
type I, within a section of one of the initial bars, and in case of
type II, between reflective faces of sections of two initial bars
(which were, during step D), neighboring initial bars).
[0100] When further bars are used in the manufacture of the optical
light guide elements such that each of the produced optical light
guide elements comprises a portion of at least one of the further
bars, another type optical light guide elements can be
manufactured, referred to as type III optical light guide element.
Details of further bars and related methods are described
below.
[0101] For a type III optical light guide element, light
propagating in the optical light guide element along the main
direction between two reflective faces of the optical light guide
element (the two reflective faces can, e.g., originate from the
upper and lower face of the plate, respectively) propagates in a
transparent solid material of a further bar, wherein it is
optionally possible that said light propagates, in addition, in
vacuum or in a gas present between the two reflective faces of the
optical light guide element (i.e. in at least one cavity of the
optical light guide element).
[0102] In some embodiments, the light guide elements, e.g., each of
the light guide elements, comprise at least one optoelectronic
component each.
[0103] The optoelectronic component can be accommodated in the
cavity (cf. type II and type III optical light guide elements
above).
[0104] As has been described above for several constituents of the
optical light guide elements, said constituents can be made at
least in part of a non-transparent dielectric material and/or can
be at least in part constituted by a section of a printed circuit
board. The optoelectronic component(s) can be attached, e.g., to
one of said constituents.
[0105] The optoelectronic components can, e.g., be attached to the
plate before separating the plate into the initial bars.
[0106] The optoelectronic components can, e.g., be attached to the
first and/or on the second substrate before attaching the
respective substrate to the bar arrangement.
[0107] The optoelectronic components can, e.g., be attached to the
at least one further substrate before carrying out a segmenting
step (in which the prism bars are segmented) for obtaining the at
least two parts, or even before applying the at least one further
substrate to the prism bars.
[0108] The at least one optoelectronic component can be, e.g., an
active optical component. It can be a MEMS (microelectromechanical
system), such as an array of actuable mirrors.
[0109] It can be a light emitting component, e.g., for producing
light to be emitted from the optical light guide element in
addition to light guided through the optical light guide element.
The light emitting component can be, e.g., a light emitting diode
or a laser such as VCSEL (vertical cavity surface emitting
laser).
[0110] It can be a light sensing component, e.g., for sensing light
guided through the optical device, such as for sensing a fraction
of the light guided through the optical device. The light emitting
component may be, e.g., a photodiode.
[0111] A new type of optical device can be obtained this way, e.g.,
an optical device which is an opto-electronic module having light
guide properties, or an optical light guide element including an
active optical component.
[0112] There is a second aspect of the invention, which is more
general. Several features and steps of the first aspect of the
invention may in fact be optional and thus be omitted.
[0113] E.g., steps A) and B) may be optional. The initial bars may
be obtained or manufactured in a different way.
[0114] And the initial bars do not necessarily need to have two
reflective faces, e.g., a single one may be sufficient.
[0115] And the initial bars do not need to not have a prism shape
with a rectangular base. E.g., the base may be differently shaped:
E.g., at least one side face of the initial bars may be curved.
E.g., it is possible that curved (and not flat) reflective faces
are provided.
[0116] However, if the first and second substrates are attached to
the positioned initial bars, the provision of initial bars with
planar and mutually parallel side faces may be of advantage.
[0117] It is also possible to conduct the plurality of cuts through
the plate (cf. step B)) which run parallel to each other and
parallel to the initial-bar directions in such a way that the
create cut faces which are not perpendicularly aligned to the upper
and lower faces, but, e.g., aligned at an obtuse angle with the
upper face and aligned at an acute angle with the lower face or,
vice versa aligned at an acute angle with the upper face and
aligned at an obtuse angle with the lower face. Therein, the angles
may be those which are visible in a view along the respective
initial-bar direction.
[0118] Attaching only one substrate to the positioned initial bars
may be sufficient, such that no second substrate is needed (cf.
step D)). And even further, provided that a suitable positioning
device or jig is used for positioning and fixing the initial bars,
it is possible to do without both, the first and the second
substrate.
[0119] The positioning of the initial bars in a row not necessarily
requires that they are positioned at a distance to each other. I.e.
they may be positioned adjacent to each other, e.g., in particular
if only one side face of each initial bar is reflective while an
opposite side face may be non-reflective. However, for reducing
stray light and minimizing intensity loss for light passing through
the optical light guide elements, it may be of advantage to provide
that no additional material interface (solid-to-solid, or
solid-to-gas or solid-to-vacuum) is present between two reflective
faces of the optical light guide elements between which light
propagates in the optical light guide element and by which a light
propagation direction is changed.
[0120] However, it is of course possible to provide, also in the
second aspect of the invention, any of the above-described features
and any combination of two or more of the described features.
[0121] In the second aspect, the invention can be described, e.g.,
by the following method:
[0122] A method for manufacturing optical light guide elements, the
method comprising [0123] a) providing a plurality of bars referred
to as initial bars, each initial bar extending along a respective
initial-bar direction from a first bar end to a second bar end and
having a first side face extending from the first bar end to the
second bar end, the first side face being reflective; [0124] b)
positioning the initial bars in a row with their respective
initial-bar directions aligned parallel to each other and with
their respective first surfaces facing towards a neighboring one of
the initial bars; [0125] c) fixing the plurality of initial bars
with respect to each other in the position achieved in step b) to
obtain a bar arrangement; [0126] d) segmenting the bar arrangement
into bars referred to as prism bars each of which comprises a
portion of at least two different ones of the plurality of initial
bars, by conducting a plurality of cuts through the bar
arrangement; in particular wherein the cuts can be parallel cuts;
[0127] e) segmenting the prism bars into parts.
[0128] Each of the parts may be comprised in one of the optical
light guide elements.
[0129] Each of the parts may comprise (or even be) one of the
optical light guide elements.
[0130] There are steps d') and d'') each of which may replace or
complement step d): [0131] d') segmenting the bar arrangement into
bars referred to as prism bars by separating the bar arrangement
into parts along cut lines, wherein the cut lines are at an angle
with the initial-bar directions; [0132] d'') segmenting the bar
arrangement into bars referred to as prism bars by separating the
bar arrangement into sections by creating cut faces which are at an
angle with respect to the initial-bar directions.
[0133] In one embodiment, the initial bars are positioned in a
distance to each other. But they may, however alternatively be
positioned adjacent each other, in particular if, for each of the
initial bars, a side face located opposite to the first side face
is not reflective.
[0134] In the bar arrangement, the initial bars are, in one
embodiment, positioned in a distance to each other or are, in
another embodiment, positioned adjacent to each other.
[0135] The positioning mentioned in step b) may be an equidistant
positioning of the initial bars.
[0136] In one embodiment, each of the initial bars has a third side
face extending from the first bar end to the second bar end,
wherein the first side face is reflective. The third side face can
be at a distance from the first side face. E.g., the first and the
third side faces can be non-adjacent to each other. They can be,
e.g., parallel to each other and/or mutually opposite faces of the
respective initial bar.
[0137] In one embodiment, the method comprises [0138] a*) providing
a plurality of bars referred to as further bars, each further bar
extending along a respective further-bar direction from a first
further bar end to a second further bar end; [0139] b*)
positioning, in step b), each of the further bars between two
neighboring ones of the initial bars with their respective
further-bar direction aligned parallel to the initial-bar
directions; [0140] c*) fixing, in step c), the plurality of further
bars with respect to each other and with respect to the initial
bars in the position achieved in step b) to obtain the bar
arrangement.
[0141] After segmenting the bar arrangement, each of the prism bars
can comprise a portion of at least two different ones of the
plurality of further bars.
[0142] The further bars can be, in particular, congeneric further
bars.
[0143] In one embodiment, each of the first side faces comprises a
first reflective coating. In this case, the first side faces can be
reflective due to the first reflective coatings. In particular it
can be provided that each of the initial bars has a third side face
extending from the first bar end to the second bar end. In this
case, it may be provided that each of the third side faces
comprises a third reflective coating. In this case, the third side
faces can be reflective due to the third reflective coatings.
[0144] However, the reflectivity of the first side faces (and, if
present, optionally also the reflectivity of the third side faces)
can, in some embodiments, be due to total internal reflection
(TIR). In this case, a material comprised in the initial bars has a
relatively high index of refraction, e.g., an index of refraction
of at least 1.3, or of at least 1.4, or of at least 1.5. In the
manufactured optical light guide elements, the first side faces
(and, if present, optionally also the third side faces) can be
interfacing a gas such as, e.g., air. This way, relatively low
refractive indices can be sufficient for TIR.
[0145] Each of the manufactured optical light guide elements
defines at least one light path for light entering the optical
light guide element, passing through the optical light guide
element and exiting the optical light guide element. Said at least
one light path can comprise a path along which light can propagate
along the above-mentioned main direction between two reflective
faces of the optical light guide element.
[0146] In case the reflectivity of the first side faces (and, if
present, optionally also the reflectivity of the third side faces)
is due to total internal reflection (TIR), light propagating in the
respective manufactured optical light guide element is reflected at
the respective first side face (and, if present, optionally also by
the respective third side faces) by TIR.
[0147] In one embodiment, each of the initial bars has a first, a
second, a third and a fourth side faces, each extending from the
first to the second bar end, the first and second side faces being
planar faces aligned parallel to each other, the third and fourth
side faces being separated from each other by and arranged between
the first and the second side faces. In particular, the third side
face may be reflective (in addition to the first side face).
[0148] One or more features described for the first aspect of the
invention may, of course, be provided in the second aspect of the
invention.
[0149] E.g., the various constituents such as initial bars, prism
bars, can be at least in part constituted by a section of a printed
circuit board. And/or at least one opto-electronic component can be
attached thereto.
[0150] As is obvious from the above, step C) corresponds to step
b), step D) can be understood as a specific version of step c),
step E) corresponds approximately to step d), and step F)
corresponds to step e).
[0151] The invention can furthermore relate to optical light guide
elements. Those optical light guide elements can be, e.g., optical
light guide elements manufactured as herein described.
[0152] And the optical light guide element can be, e.g., an optical
light guide element for guiding light inside the optical light
guide element between two reflective faces of the optical light
guide element referred to as first and second reflective faces
along a main direction of the optical light guide element. Said
light can in particular be light incident on the optical light
guide element along an incidence direction and exiting the optical
light guide element along an exit direction. The main direction is
at an angle with the incidence direction and at an angle with the
exit direction. And the optical light guide element comprises
[0153] two mutually parallel outer side panels referred to as first
and third outer side panels, the main direction being aligned
parallel to the first and third outer side panels; [0154] a first
prism comprising two base faces aligned parallel to the first and
third outer side panels, one attached to the first outer side
panel, the other attached to the third outer side panel.
[0155] The first prism comprises, located between the first and
third outer side panels, the first reflective face shaped and
aligned for redirecting light incident on the optical light guide
element along the incidence direction into the main direction. The
optical light guide element comprises, located between the first
and third outer side panels, a second reflective face shaped and
aligned for redirecting light redirected by the first reflective
face into the main direction to exit the optical light guide
element along the exit direction. The second reflective face is
[0156] in a first case, comprised in the first prism; or [0157] in
a second case, comprised in a second prism of the optical light
guide element, the second prism comprising two further base faces
aligned parallel to the first and third outer side panels, one
attached to the first outer side panel, the other attached to the
third outer side panel, wherein the second prism comprises, between
the two further base faces, the second reflective face.
[0158] The first and second reflective faces can be aligned
parallel to each other.
[0159] The first and second reflective faces can be at an angle of
45.degree..+-.10.degree. with the main direction.
[0160] The first and second reflective faces can be at an angle of
45.degree..+-.5.degree. with the main direction.
[0161] The first and second reflective faces can be at an angle of
45.degree. with the main direction.
[0162] In the first case, the base faces can have a parallelogram
shape.
[0163] In one embodiment, the first reflective face is reflective
due to a reflective coating.
[0164] In another embodiment, the first reflective face is
reflective due total internal reflection.
[0165] In one embodiment, the second reflective face is reflective
due to a reflective coating.
[0166] In another embodiment, the second reflective face is
reflective due total internal reflection.
[0167] In one embodiment, the optical light guide element
comprises, in addition, two mutually parallel outer side panels
referred to as second and fourth outer side panels, the main
direction being aligned parallel to the second and fourth outer
side panels. In this embodiment, at least one of the second and
fourth outer side panels can comprise at least one lens element.
The lens element can be arranged to be traversed by light incident
on the optical light guide element along the incidence direction
and exiting the optical light guide element along the exit
direction.
[0168] Of course, the optical light guide element can inherit any
feature arising from one of the described manufacturing
methods.
[0169] Further embodiments and advantages emerge from the following
description and the enclosed figures.
[0170] Below, the invention is described in more detail by means of
examples and the included drawings. The figures show:
[0171] FIG. 1 a photography of an optical light guide element of a
first type (type I);
[0172] FIG. 2 a schematical perspective illustration of an optical
light guide element of a first type (type I);
[0173] FIG. 3 a photography of an optical light guide element of a
second type (type II);
[0174] FIG. 4 a schematical perspective illustration of an optical
light guide element of a second type (type II);
[0175] FIG. 5 a schematical perspective illustration of an optical
light guide element of a first type (type I), manufactured using
further bars;
[0176] FIG. 6 a schematical perspective illustration of an optical
light guide element of a second type (type II) using total internal
reflection, and manufactured using further bars;
[0177] FIGS. 7a-7c schematical illustrations in a top view of a
manufacture of initial bars;
[0178] FIGS. 8a-8c schematical illustrations in a cross-sectional
view of a manufacture of initial bars;
[0179] FIGS. 9a-9c schematical illustrations in a cross-sectional
view of a positioning of initial bars using a jig;
[0180] FIGS. 10a-10b schematical illustrations in a cross-sectional
view of a positioning of initial bars using another jig;
[0181] FIGS. 11a-11c schematical illustrations in a top view of a
manufacture of a bar arrangement;
[0182] FIGS. 12a-12c schematical illustrations in a cross-sectional
view of the manufacture of a bar arrangement illustrated in FIGS.
11a-11c;
[0183] FIG. 13 a schematical illustration in a top view of a
manufacture of prism bars from the bar arrangement of FIGS. 11c,
12c;
[0184] FIG. 14 a schematical illustration in a cross-sectional view
of the manufacture of prism bars illustrated in FIG. 13;
[0185] FIG. 15 a schematical cross-sectional view of a prism bar as
obtained according to FIGS. 13, 14;
[0186] FIG. 16 a schematical illustration in a cross-sectional view
of the prism bar of FIG. 15;
[0187] FIG. 17 a schematical cross-sectional view of a prism
bar;
[0188] FIG. 18 a schematical illustration in a cross-sectional view
of an attaching of the prism bar of FIG. 17 to a lens wafer for
manufacturing a type I optical light guide element;
[0189] FIG. 19 a schematical cross-sectional view of the prism bar
of FIG. 17 sandwiched between the lens wafer illustrated in FIG. 18
and another lens wafer;
[0190] FIG. 20 a schematical cross-sectional view of the wafer
stack of FIG. 19, with diffractive optical elements attached;
[0191] FIG. 21 a schematical cross-sectional view of an optical
light guide element of type I obtained by separating the wafer
stack of FIG. 20;
[0192] FIG. 22 a schematical cross-sectional view of a prism
bar;
[0193] FIG. 23 a schematical illustration in a cross-sectional view
of a wafer stack for manufacturing a type I optical light guide
element, comprising the prism bar of FIG. 22 attached to a lens
wafer;
[0194] FIG. 24 a schematical cross-sectional view of the wafer
stack of FIG. 23 with another lens wafer attached;
[0195] FIG. 25 a schematical cross-sectional view of the wafer
stack of FIG. 24, with diffractive optical elements attached;
[0196] FIG. 26 a schematical cross-sectional view of an optical
light guide element of type II obtained by separating the wafer
stack of FIG. 25;
[0197] FIGS. 27a-27c schematical illustrations in a top view of a
manufacture of a bar arrangement comprising initial bars and
further bars;
[0198] FIGS. 28a-28c schematical illustrations in a cross-sectional
view of the manufacture of a bar arrangement illustrated in FIGS.
27a-27c;
[0199] FIG. 29 a schematical illustration in a top view of a
manufacture of a prism bar from the bar arrangement of FIGS. 27c,
28c;
[0200] FIG. 30 a schematical illustration in a cross-sectional view
of the manufacture of a prism bar illustrated in FIG. 29;
[0201] FIG. 31 a schematical cross-sectional view of a prism bar as
obtained according to FIGS. 29, 30;
[0202] FIG. 32 a schematical cross-sectional illustration of the
prism bar of FIG. 31, with separation lines illustrated for
producing type I optical light guide elements with further bars as
filler bars;
[0203] FIG. 33 a schematical cross-sectional illustration of the
prism bar of FIG. 31, with separation lines illustrated for
producing type I optical light guide elements with initial bars as
filler bars;
[0204] FIG. 34 a schematical illustration of a bar arrangement
comprising further bars and, at a distance thereto, initial bars
which are not coated;
[0205] FIG. 35 a schematical cross-sectional illustration of the
bar arrangement of FIG. 35 sandwiched between two substrates;
[0206] FIG. 36 a schematical cross-sectional illustration of a
prism bar obtained from the bar arrangement of FIG. 35, with
separation lines illustrated for use as a type I optical light
guide element with reflectivity by total internal reflection and
with further bars as filler bars;
[0207] FIG. 37 a schematical cross-sectional illustration of a
prism bar obtained from a bar arrangement with filler bars at a
distance to the initial bars, with separation lines illustrated for
use as a type III optical light guide element with initial bars as
filler bars;
[0208] FIG. 38 a schematical cross-sectional view of an optical
light guide element of type II including in the cavity an
opto-electronic component at a side panel;
[0209] FIG. 39 a schematical cross-sectional view of an optical
light guide element of type II including in the cavity an
opto-electronic component at a prism.
[0210] The described embodiments are meant as examples or for
clarifying the invention and shall not limit the invention.
[0211] FIG. 1 is a photography of an optical light guide element 1
of a first type (type I); FIG. 2 a schematical perspective
illustration of an optical light guide element of a first type
(type I). Since the optical light guide elements 1 of FIGS. 1 and 2
are, to a large extent, identical (they differ mainly in some
dimensions), they are described together, in the following.
[0212] The optical light guide element 1 includes a prism 40 having
two reflective faces 51, 52 embodied, e.g., by two reflective
coatings 21r, 23r. Light entering the optical light guide element 1
through lens element 15 is reflected by reflective face 52 along a
main direction of the optical light guide element 1 onto reflective
face 51 which again redirects the light out of optical light guide
element 1, e.g., through another lens element (which would be not
visible in FIGS. 1, 2).
[0213] Optical light guide element 1 includes first and third outer
side panels 61, 63 which are aligned parallel to base faces 71, 72
of prism 40, and to which base faces 71, 72 are fixed.
[0214] Optical light guide element 1 further includes second and
fourth outer side panels 62, 64, which are sections 13a and 14a,
respectively, of a lens wafer (cf. below).
[0215] Optical light guide element 1 has, within a cuboid described
by the outer side panels 61, 62, 63, 64, two cavities 9, 9'.
[0216] In the same way as FIGS. 1 and 2, FIGS. 3 and 4 illustrate
an optical light guide element 1 of a second type (type II). Since
many features of the illustrated type II optical light guide
element 1 of FIGS. 3, 4 are identical with features of the optical
light guide element 1 of FIGS. 1, 2, mainly the differences will be
explained in the following.
[0217] In this optical light guide element 1 of FIGS. 3, 4, the
optical light guide element 1 includes two prisms 41, 42 which are
at a distance. Between prisms 41, 42, there is a cavity 9''. Cavity
9'' can be enclosed, in particular hermetically enclosed, by outer
side panels 61, 62, 63, 63 and prisms 41, 42, as it is the case in
the embodiment of FIGS. 3, 4.
[0218] Prism 41 has base faces 71, 72, and prism 42 has base face
73 and another base face not visible in FIGS. 3, 4. Each of the
base faces is aligned parallel to and is fixed to one of outer side
panels 61, 62.
[0219] Light entering optical light guide element 1 through lens
element 15 is reflected by first and second reflective faces 51, 52
and propagates between first and second reflective faces 51, 52
inside cavity 9'' along the main direction.
[0220] FIG. 5 is a schematical perspective illustration of an
optical light guide element 1 of the first type (type I), which is
manufactured using further bars (cf. below).
[0221] In this case, optical light guide element 1 includes three
prisms 40, 41, 42 which roughly correspond to prisms 40, 41, 42 of
FIGS. 1 through 4. As illustrated in FIG. 5, prism 40 can be
adjacent to both, prism 41 and prism 42. In this case, it can be
provided that optical light guide element 1 comprises no
cavity.
[0222] There are different ways of manufacturing a light guide as
illustrated in FIG. 5. In one way, both, first and second
reflective faces 51, 52 (which may be realized by reflective
coatings 21r and 23r, respectively), are included in prism 40. In
this case, a reflective coating of one of the other prisms 41, 42
can be dispensed with. And in this case, the optical light guide
element 1 is of type I.
[0223] In another way, reflective face 51 is realized by prism 41,
e.g., by a reflective coating 21r, and reflective face 52 is
realized by prism 42, e.g., by a reflective coating 23r. In this
case, the optical light guide element 1 is of type III, because
light propagating inside optical light guide element 1 along the
main direction does not propagate through a prism bearing the
reflective faces (which would be obtained from an initial bar, cf.
below).
[0224] And still in another way, reflective face 52 is realized by
prism 42, and reflective face 51 is realized by prism 40; or
reflective face 52 is realized by prism 40, and reflective face 51
is realized by prism 41. This way, optical light guide element 1
could be a type I optical light guide element.
[0225] The base faces of the prisms are, also in case of FIG. 3,
fixed at the inner side of outer side panels 61 and 63,
respectively.
[0226] FIG. 6 is a schematical perspective illustration of an
optical light guide element 1 of a second type (type II) using
total internal reflection (TIR), and manufactured using further
bars (cf. below).
[0227] In this case, optical light guide element 1 includes three
prisms 40, 41, 42 which roughly correspond to prisms 40, 41, 42 of
FIGS. 1 through 5. However, prism 40 is free of a reflective
coating at reflective faces 51, 52. Between prism 40 and prism 41
and between prism 40 and prism 42, cavities 9 and 9', respectively,
are present. The transparent material from which prism 40 is made
has a relatively high index of refraction, such that light entering
optical light guide element 1 through lens 15 will be reflected
towards reflective face 52 by reflective face 51 by TIR. E.g., the
index of refraction of prism 40 can be 1.5 or higher. In the
cavities 9, 9', there can be a vacuum or a gas such as air.
[0228] Prisms 41, 42 can protect reflective faces 51, 52 from dirt
and damage.
[0229] In another embodiment based on FIG. 6, prisms 41, 42 can be
dispensed with.
[0230] In the following, ways of manufacturing optical light guide
elements, such as optical light guide elements 1 of one or more of
FIGS. 1 through 6, are explained. In many of the Figures, small
coordinate systems are symbolized for explaining the orientation of
the illustrated parts. Therein, x, y, z designate coordinates
related to the initial bars, while x', y', z' designate coordinates
related to prism bars.
[0231] The manufacturing can be accomplished on wafer level, thus
making possible to manufacture high numbers of high precision parts
within a relatively small period of time and/or by means of a
relatively low number of processing steps.
[0232] FIGS. 7a-7c are schematical illustrations in a top view of a
manufacture of initial bars 2. FIGS. 8a-8c are schematical
illustrations in a cross-sectional view of the manufacture of
initial bars 2.
[0233] FIGS. 7a, 8a illustrate a plate 6 having an upper face 6a
and a lower face 6b, wherein a first reflective coating 21r is
present at face 6a, and a second reflective coating 23r is present
at face 6b. Between coatings 21r, 23r, an optically transparent
material 6c can be present.
[0234] As is clear from the above and from the below, reflective
coatings, such as coatings 21r, 23r, can, in some instances, be
dispensed with.
[0235] Plate 6 is, in some instances further below, also referred
to as "P/C wafer".
[0236] In FIGS. 7b, 8b, separation lines are indicated by dashed
lines, which are also symbolized in the coordinate systems. By
separating plate 6 along these lines, a plurality of initial bars 2
is obtained, as illustrated in FIGS. 7c, 8c.
[0237] Each initial bar 2 has a first bar end 28 and a second bar
end 29 and four side faces 21, 22, 23, 24, wherein reflective
coating 21r is at side face 21, and reflective coating 23r is at
side face 23.
[0238] In order to produce a bar arrangement 20 (cf., e.g., FIGS.
11a, 12a), the initial bars 2 have to be positioned suitably.
Therein, reflective faces of the initial bars 2 face each other.
I.e. with respect to the mutual orientation the initial bars have
during separation of plate 6 (cf. FIGS. 7c, 8c), each initial bar
is rotated by 90.degree. about the y axis corresponding to an
initial-bar direction D, cf. FIG. 7c.
[0239] One way of positioning the initial bars 2 is to use a jig 8
as illustrated in FIGS. 9a-9c.
[0240] FIGS. 9a-9c are schematical illustrations in a
cross-sectional view of a positioning of initial bars 2 using a jig
8.
[0241] Jig 8 has a plurality of protrusions 81 on which an initial
bar 2 can be positioned each. After attaching initial bars 2 to
protrusions 81, spacers 8a are inserted between the initial bars 2
(cf. FIG. 9b). The spacers 8a can also be considered shims.
[0242] By application of a force, e.g., by a spring or by applying
a vacuum, a suitable, e.g., equidistant, spacing of the initial
bars 2 is achieved, cf. FIG. 9c.
[0243] Also other jigs may, alternatively, be used, e.g., jig 8' as
illustrated in FIGS. 10a, 10b.
[0244] FIGS. 10a-10b are schematical illustrations in a
cross-sectional view of a positioning of initial bars 2 using
another jig 8'.
[0245] Jig 8' has grooves 8b into which initial bars 2 can be
inserted, thus ensuring a precise mutual alignment of the initial
bars 2.
[0246] A jig is used for the positioning only and will be removed
later.
[0247] Positioning the initial bars alone or together with further
bars (cf. below) without using a jig is possible, too, e.g., by
simply pushing the bars against each other, each one against its
one or two neighboring ones, cf., e.g., FIGS. 27a, 28a below.
[0248] FIGS. 11a-11c are schematical illustrations in a top view of
a manufacture of a bar arrangement 20, e.g., based on bars
positioned as described above. FIGS. 12a-12c are schematical
illustrations in a cross-sectional view of the manufacture of a bar
arrangement illustrated in FIGS. 11a-11c.
[0249] FIGS. 11a, 12a show the bars positioned as required for the
desired bar arrangement. A jig possibly used for the positioning of
the initial bars 2 is not illustrated in FIGS. 11a, 12a.
[0250] The initial bars 2 can be fixed relative to each other by
attaching one or two substrates to the bar arrangement 20. After
attachment to a first substrate, a jig, if applied before, can be
removed from the bar arrangement. However, the positioned initial
bars as illustrated, e.g., in FIGS. 11a, 12a can represent a bar
arrangement, too.
[0251] FIGS. 11b, 12b illustrate attaching a first substrate 11 to
bar arrangement 20.
[0252] FIGS. 11c, 12c illustrate attaching a second substrate 12 to
bar arrangement 20.
[0253] Now, the initial bars 2 are sandwiched between first and
second substrates 11, 12. A wafer stack is obtained in which the
initial bars 2 are mutually positioned with high precision.
[0254] In a next step, the obtained wafer stack of FIGS. 11c, 12c
is separated into bars referred to as prism bars. Therein, cut
lines C of the separation are at an angle with the initial-bar
lines D, e.g., at an angle of 45.degree., as illustrated below.
[0255] FIG. 13 is a schematical illustration in a top view of a
manufacture of prism bars 4 from the bar arrangement 20 of FIGS.
11c, 12c; and FIG. 14 is a schematical illustration in a
cross-sectional view of the manufacture of prism bars 4 illustrated
in FIG. 13.
[0256] FIG. 15 is a schematical cross-sectional view of a prism bar
4 as obtained according to FIGS. 13, 14; and FIG. 16 is a
schematical illustration in a cross-sectional view of the prism bar
of FIG. 15. Note the coordinate systems. FIG. 15 is basically a
detail of FIG. 13.
[0257] In the coordinate system of the prism bar 4, x' is a
coordinate along the extension of the prism bar 4--which runs
somewhere (depending on the cutting angle) between the x and y
coordinates of the initial bar coordinate system. It corresponds,
in the produced optical light guide element to the main direction M
of the optical light guide element. And z' is a height coordinate
of the prism bar 4--which corresponds to the opposite direction of
the y coordinate.
[0258] FIG. 17 is a schematical cross-sectional view of a prism bar
4, illustrated in a way slightly different from FIG. 15. Reflective
coatings are symbolized by thick lines.
[0259] FIG. 18 is a schematical illustration in a cross-sectional
view of an attaching of the prism bar 4 of FIG. 17 to a lens wafer
13 for manufacturing a type I optical light guide element. Lens
wafer 13--which may also be considered a "further
substrate"--includes a plurality of lens elements 15. It is
possible to position a plurality of prism bars 4 on such a lens
wafer 13, e.g., using pick-and-place.
[0260] FIG. 19 is a schematical cross-sectional view of the prism
bar of FIG. 17 sandwiched between the lens wafer illustrated in
FIG. 18 and another lens wafer 14 (which may also be considered a
"further substrate").
[0261] FIG. 20 is a schematical cross-sectional view of the wafer
stack of FIG. 19, with diffractive optical elements 18 attached,
e.g., by pick-and-place on wafer level. The dashed lines indicate
dicing lines, for a next step in which the wafer stack is
singulated into parts.
[0262] FIG. 21 is a schematical cross-sectional view of an optical
light guide element 1 of type I obtained by separating the wafer
stack of FIG. 20 in parts as indicated in FIG. 20. A light path
into, through and out of the optical light guide element 1 is
illustrated by the dotted line designated L. From this, it is
readily understood how the properties of initial bars 2 and prism
bars 4 and their constituents translate into properties of the
optical light guide element 1.
[0263] FIGS. 22 to 25 illustrate, in the same way as FIGS. 17 to 20
do, the manufacture of a wafer stack with prism bars 4 and two
further wafers 13, 14 such as the illustrated lens wafers 13,
14.
[0264] FIG. 26 is a schematical cross-sectional view of an optical
light guide element of type II obtained by separating the wafer
stack of FIG. 25 into parts. A light path into, through and out of
the optical light guide element 1 is illustrated by the dotted line
designated L. From this, it is clear how the properties of initial
bars 2 and prism bars 4 and their constituents translate into
properties of the optical light guide element 1.
[0265] The addition of one or more further substrates such as lens
wafers 13 and/or 14 as described above is generally an option. It
is, accordingly, also possible to separate a prism bar 4 (such as
the one of FIGS. 15, 16) into parts--without attaching further
substrates beforehand.
[0266] As has been mentioned before, it is possible to make use of
"further bars", in addition to the initial bars 2, in the
manufacture of optical light guide elements. This opens up the
possibility to realize further embodiments.
[0267] The initial bars 2 can, in some embodiments, be congeneric,
as illustrated in the examples above.
[0268] And, the further bars can, in some embodiments, be
congeneric, as illustrated in the examples below.
[0269] FIGS. 27a-27c are schematical illustrations in a top view of
a manufacture of a bar arrangement 20 comprising initial bars 2 and
further bars 3. FIGS. 28a-28c are schematical illustrations in a
cross-sectional view of the manufacture of a bar arrangement
illustrated in FIGS. 27a-27c. Further bars 3 can be manufactured in
the same way as initial bars 2 are manufactured. They may be
obtained by separating a plate, referred to as further plate, into
bars. Such a further plate can, e.g., be provided with a reflective
coating on one of its large faces or with reflective coatings on
both of its large faces. But in some embodiments, the further plate
does not have a reflective coating.
[0270] FIG. 29 is a schematical illustration in a top view of a
manufacture of a prism bar 4 from the bar arrangement of FIGS. 27c,
28c; and FIG. 30 is a schematical illustration in a cross-sectional
view of the manufacture of a prism bar illustrated in FIG. 29.
[0271] The method steps illustrated in FIGS. 27 through 30 are
clear, at least when taking FIGS. 11 through 14 into
consideration.
[0272] FIG. 31 is a schematical cross-sectional view of a prism bar
4 as obtained according to FIGS. 29, 30.
[0273] Depending on where the prism bar 4 is separated into parts,
different type I optical light guide elements can be obtained.
[0274] FIG. 32 is a schematical cross-sectional illustration of the
prism bar 4 of FIG. 31, with separation lines illustrated for
producing type I optical light guide elements with further bars 3
as filler bars. The light path is referenced L.
[0275] FIG. 33 is a schematical cross-sectional illustration of the
prism bar 4 of FIG. 31, with separation lines illustrated for
producing type I optical light guide elements with initial bars 2
as filler bars.
[0276] FIG. 34 is a schematical illustration in a top view of a bar
arrangement 20 comprising further bars 3 and, at a distance
thereto, initial bars 2 which are not coated. FIG. 35 is a
schematical cross-sectional illustration of the bar arrangement 20
of FIG. 35 sandwiched between two substrates 11, 12. The space
between neighboring initial bars 2 and further bars 3 is referenced
99.
[0277] Separating the bar arrangement 20 of FIGS. 34, 35 like in
the embodiments described above, results in prism bars 4 such as
the one illustrated in FIG. 36.
[0278] FIG. 36 is a schematical cross-sectional illustration of a
prism bar 4 obtained from the bar arrangement of FIG. 35, with
separation lines illustrated for producing type I optical light
guide elements with reflectivity at reflective faces by total
internal reflection and with further bars 3 as filler bars.
[0279] FIG. 37 is a schematical cross-sectional illustration of a
prism bar 4 obtained from a bar arrangement with filler bars 3 at a
distance to the initial bars 2 (spaces referenced 99), with
separation lines illustrated for producing type III optical light
guide elements with initial bars 2 as filler bars.
[0280] FIG. 38 is a schematical cross-sectional view of an optical
light guide element 1 of type II including in the cavity 9'' an
opto-electronic component 90 at side panel 64. Side panel 64 is, in
part, made of a non-transparent dielectric material. Side panel 64
can be, at least in part, a PCB.
[0281] Opto-electronic component 90 is attached to contact pads
which are in electrical contact to further contact pads 99 outside
cavity 9'' by vias 95. By providing electrical contacts across the
non-transparent dielectric material, optical light guide element 1
can be supplied with power and/or be controlled from outside
optical light guide element 1.
[0282] In the illustrated example, optoelectronic component 90 is a
light emitter. This way, light produced by optical light guide
element 1 (more specifically: by optoelectronic component 90) can
propagate along a path similar to (e.g., parallel to) the path of
light guided through optical device 1.
[0283] In panel 62, a transparent region 62a is provided to which
lens element 15 is attached. Panel 64 comprises a transparent
region, too, for letting light pass through the otherwise
non-transparent panel.
[0284] Considering the manufacturing steps and methods above (cf.
also, e.g., FIGS. 23, 24), it is clear that the optical light guide
element 1 can be produced when a printed circuit board is combined
with the prism bars, i.e. the printed circuit board (with
transparent regions) can be used as a further substrate which
replaces or is a lens wafer. E.g., the further substrates to be
used can be printed circuit boards to which opto-electronic
components are attached. Accordingly, printed circuit board
assemblies can be used as the further substrates.
[0285] FIG. 39 is a schematical cross-sectional view of an optical
light guide element 1 of type II including in the cavity 9'' an
opto-electronic component 90 at prism 42. This can be understood as
an example for the possibility to produce a superposition of
diffuse light (diffuse light produced by optical device 1, more
specifically by opto-electronic component 90) and directed light
(guided through optical light guide element 1).
[0286] FIG. 39 also illustrates that more than one passive optical
component may be included in optical device 1. E.g., one (15) may
be present at a panel (62) through which light exits optical light
guide element 1, and another one (15') may be present at panel 64,
attached to transparent region 64a through which light enters
optical light guide element 1.
[0287] Considering the manufacturing steps and methods above (cf.
also, e.g., FIGS. 7a-c, 8a-c), it is clear that the optical light
guide element 1 can be produced when printed circuit boards are
used as the initial bars. E.g., the plates 6 used to produce the
initial bars 2 can be printed circuit boards, and opto-electronic
components can be placed thereon. Accordingly, printed circuit
board assemblies can be used as the plates 6.
[0288] As has been mentioned above, it is also possible to use
initial bars 2 which are reflective only at one side (but not at
the opposite side). They can be positioned, e.g., parallel to each
other, to produce a bar arrangement, optionally with further bars 3
between the initial bars, wherein the further bars 3 can optionally
have no reflective face, one reflective face, or two (oppositely
arranged) reflective faces. Spaces 99 between neighboring bars can
optionally be provided.
[0289] An exemplary method is described in detail in the following.
The enclosed Figures illustrate and partially also comment details
of that and of possible further methods.
1. Start with smooth (e.g., polished), coated wafer (herein "p/c
wafer"--which corresponds to the "plate" described before). The
first coating may be comprised of a highly reflective metal such as
aluminum, silver, and/or gold or a dielectric material and may
further comprise an additional coating material (e.g. Silflex) to
enhance the optical properties of the metal coating and/or provide
environmental protection. For example, when a silver coating is
used the additional coating could prevent or reduce tarnishing. 2.
The p/c wafer is further coated with a protective coating. The
protective coating, e.g. a resin and/or photoresist, prevents
damage to the first coating (e.g. a silver, Silflex coating) in the
following step. 3. The p/c wafer is put into contact with a first
dicing substrate (e.g. UV dicing tape). 4. The p/c wafer above is
segmented into bars (herein "p/c bars"--which correspond to the
"initial bars" described before). Segmentation may be accomplished
via dicing, laser cutting and/or laser-scribe-and-break. In some
cases when dicing, several passes of the dicing blade may be
employed in order to reduce stresses in the p/c bars. 5. The p/c
bars are released from the first dicing substrate (e.g. if UV
dicing was employed, the assembly above is exposed to UV radiation
in order to remove the UV dicing tape). 6. Alternative/additional
step to the above, following 3: An easily removable adhesive (e.g.
a wax or resin) is applied to the p/c wafer and an additional p/c
wafer is put into contact with the first p/c wafer via the easily
removable adhesive. Force may be applied to better adhere, spread
the adhesive. This step may be repeated such that a multiple p/c
wafer stack may be made. Following segmentation (as in step 4) each
p/c bar is removed, the easily removable adhesive removed, e.g. via
solvent, and the process continues with step 7. 7. The p/c bars
above are rotated 90.degree. about the p/c bar long axis (also
referred to as "initial-bar direction") and placed into a
positioning jig, e.g. by pick-and-place technology. The positioning
jig is employed to position p/c bars precisely with respect to each
other. Several versions of positioning jigs may be employed. A
precisely machined/polished component of the positioning jig is
common to each version. The precisely machined/polished component
positions p/c bars with respect to each other (with a high degree
of accuracy). Compression, vacuum, or easily removable adhesive
is/are employed to hold the bars in place. Additional positioning
jig details are disclosed in the attached figures and in the
description. 8. After the p/c bars are fixed in place in the
positioning jig, an adhesive (e.g. an adhesive that is UV or
thermally curable, or both) is dispensed onto a first surface of
the p/c bars and/or a first substrate. When adhesive is dispensed
onto p/c bars, the adhesive is dispensed onto the long surface
perpendicular to the coated surface. The adhesive may be dispensed
via needle dispensing/jetting, or screen printing (onto the p/c
bars, first substrate, or both). The first substrate may be
transparent (e.g. a glass substrate) or may be substantially
non-transparent (e.g. PCB material such as FR4/G10 or a silicon
substrate). 9. The p/c bars (within the positioning jig) are
brought into contact with the first substrate (via the adhesive).
Force may be applied to better adhere, spread the adhesive. The
adhesive is cured with UV radiation, heat or both UV radiation and
heat, or partially cured e.g. via UV radiation alone. The form of
curing energy depends on the type of substrate material used. For
example, if the substrate is comprised of glass, UV radiation may
be used, however, if the substrate is comprised of PCB or other
non-transparent material heat may be used for curing. 10. Following
curing (or partial curing) in the previous step the positioning jig
is removed. 11. Adhesive is applied to a second surface of the p/c
bars and/or a second substrateas above (e.g. via needle
dispensing/jetting and/or screen printing). When adhesive is
dispensed onto p/c bars, the adhesive is dispensed on a surface
parallel to the first surface of the p/c bars (the surface with
adhesive); that is, on a long surface perpendicular to a coated
(metal) surface). 12. The p/c bars (adhered to the first substrate)
are brought into contact with the second substrate via the
adhesive. Force may be applied to better adhere, spread the
adhesive. 13. The adhesive applied in the previous step (step 12)
is cured with UV radiation, heat or both UV radiation and heat, or
partially cured e.g. via UV radiation alone. 14. In some instance
when previously applied adhesive is partially cured (as in steps 9
and/or 13), the adhesive may be fully cured e.g. by applying heat,
additional heat. In some cases there may be advantages to full
curing both wafers in the same step (e.g. better dimensional
stability). 15. The first substrate+p/c bars+second substrate
assembly (resulting from the previous steps--also referred to as
"sandwich wafer" or "wafer stack" before) is segmented into bars
(herein "prism bars"). Segmentation occurs at 45.degree. relative
to the p/c bars long axis and perpendicular to the plane of the
first substrate+p/c bars+second substrate. Segmentation may occur
as in the previous steps, e.g. by dicing. In some cases, many
passes may be made with the dicing blade (in which successive
amounts of material are cut away) in order to reduce stress, in
other instances, the first substrate+p/c bars+second substrate may
be diced partially from either side of the plane. 16. As the
precision/accuracy of the segmentation techniques typically
employed (as disclosed in previous steps) is not sufficient (e.g.
for dicing may be +/-50 .mu.m), the cut surface (the surface cut in
step 15) may be polished in order to obtain well defined dimensions
(e.g. +/-10 .mu.m), in some instances when such accuracy/precision
is required. These surfaces are particularly important as they
define the z-height (and the optical path of the module, i.e. the
light path inside the optical light guide element). 17. The prisms
bars generated in the previous step may be attached to a lens wafer
via adhesive and cured or partially cured (as disclosed above,
within the spirit of the above). The lens wafer may be comprised of
a transparent substrate (such as a glass wafer) or other
transparent or non-transparent material (such as a PCB material;
PCB=printed circuit board). In other cases where thermal
dissipation may be critical (e.g. for optical quality) the
substrate material may be a high (relatively high) thermal
conductivity material (e.g. sapphire). In other instances the
substrate material may be a low thermal expansion material (e.g.
sapphire or other inorganic composites). The lens wafer is further
comprised of lenses (lens elements). The lenses may be previously
formed, cured on aforementioned wafer by known wafer level
techniques. In other instances where improved lens quality is
required pick-and-place technology may be used to position
injection-molded lenses onto the aforementioned substrate (adhesive
would have been previously applied by known technologies). 18. In
some instances, additional lens wafers may be added to the lens
wafer (via adhesive) where the adhesive is cured or partially cured
as above. 19. An additional lens wafer may be added to the opposite
side (within the spirit of steps 17 and 18). Further other optical
elements may be added, and need not be added by wafer-level
technology. E.g. pick and place may be used to position diffractive
optical elements (DOEs) or other optical elements onto the lens
wafers attached above. 20. After all lens wafers and optical
elements have been added, the module is diced perpendicular to the
lens wafer plane and long axis of the prism bars.
[0290] Note in any of the previous steps when adhesive is used to
join components where their height is critical, a special adhesive
may be used that is comprised of typical adhesive material and
plastic or glass balls/spheres of a particular diameter. The
spheres precisely define the ultimate thickness of the adhesive
layer.
[0291] The various methods and embodiments described may, in some
instances, permit the manufacture of light pipes (optical light
guide elements) with a very low z height. Additionally, in some
instances, very high precision alignment of and distancing between
parts (constituents) of the light pipe and/or very high precision
alignment of the light pipe and distancing between the light pipe
and further items may be achievable. The described processes can
employ smooth (e.g., polished) material (e.g., glass or other
transparent material; or--in particular for type II light pipes,
cf. above--also non-transparent material), which may be coated with
a highly reflective coating. By smooth material we mean in the
present context material having a planar surface, typically at
least from micron scale to millimeter scale (the surface having a
low roughness), e.g., like an ordinary mirror does. The provision
of such material may make possible to overcome various technical
challenges. The smooth material can be of importance for the light
pipes. The smooth (e.g., polished and coated) sides effect that the
entire smooth material can have a very well defined thickness. This
thickness translates into a very well-defined optical path. In some
cases, the smooth material is transparent (e.g., polished glass or
a polished transparent polymer--e.g., having an index of refraction
enabling total internal reflection), and in some other cases, the
smooth material is a non-transparent (and possibly also
non-reflective) material such as PCB material (e.g.,
fiber-reinforced epoxy), and in still some other cases, the smooth
material is a reflective (in particular highly reflective)
non-transparent material such as a metal, e.g., polished
aluminium.
[0292] The smooth material (e.g., polished glass) mentioned above
provides a well defined space/optical path 1.) directly (as in FIG.
1, type I), where the smooth material defines a prism, or 2.)
indirectly (as in FIG. 3, type II), where an intervening jig with
smooth sides is used in conjunction with two smooth material wafers
to provide a well-defined optical path (the jig is only temporarily
placed between the two prisms, then removed during processing).
* * * * *