U.S. patent number RE36,711 [Application Number 09/195,076] was granted by the patent office on 2000-05-23 for method of fabricating a liquid crystal display.
This patent grant is currently assigned to LG Electronics Inc.. Invention is credited to Zvi Yaniv.
United States Patent |
RE36,711 |
Yaniv |
May 23, 2000 |
**Please see images for:
( Certificate of Correction ) ** |
Method of fabricating a liquid crystal display
Abstract
A light influencing element and the process of fabricating the
same is disclosed, wherein the light influencing element is
fabricated by disposing a layer of a substantially opaque material
upon a transparent substrate. One or more openings or wells may
then be cut or formed in the surface of the layer of opaque
material. Into such openings a light influencing material is then
disposed, preferable said materials are injected thereinto as by
ink-jet type injection heads. Liquid crystal displays and
subassemblies formed upon the light influencing elements of the
instant invention are also provided.
Inventors: |
Yaniv; Zvi (Austin, TX) |
Assignee: |
LG Electronics Inc. (Seoul,
KR)
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Family
ID: |
25397227 |
Appl.
No.: |
09/195,076 |
Filed: |
November 18, 1998 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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068305 |
May 28, 1993 |
5281450 |
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890855 |
Jun 1, 1992 |
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Reissue of: |
150788 |
Nov 12, 1993 |
05576070 |
Nov 19, 1996 |
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Current U.S.
Class: |
427/510; 156/108;
156/145; 156/310; 156/99; 427/165; 427/169; 427/269; 427/270;
427/272; 427/289; 427/389.7; 427/393.5; 427/512; 427/514; 427/521;
427/555; 427/557; 427/595; 427/596 |
Current CPC
Class: |
G02F
1/133512 (20130101); G02F 1/133516 (20130101) |
Current International
Class: |
G02F
1/1335 (20060101); G02F 1/13 (20060101); C08J
007/04 () |
Field of
Search: |
;156/99,108,145,310
;427/165,169,269,270,272,289,389.7,393.5,512,514,521,555,557,595,596,510 |
References Cited
[Referenced By]
U.S. Patent Documents
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59-123670 |
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63-205607 |
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2-287427 |
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3-10220 |
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JP |
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3-280002 |
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Dec 1991 |
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JP |
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4-30118 |
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Feb 1992 |
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JP |
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4-86801 |
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Mar 1992 |
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JP |
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4-123007 |
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Apr 1992 |
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JP |
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4-106502 |
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Apr 1992 |
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JP |
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4-123005 |
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Apr 1992 |
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JP |
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4-123006 |
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Apr 1992 |
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JP |
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59-84206 |
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May 1998 |
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JP |
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Primary Examiner: Pianalto; Bernard
Attorney, Agent or Firm: Loeb & Loeb
Parent Case Text
.Iadd.This application is the parent of a copending application,
filed Nov. 16, 1999, for Reissue of U.S. Pat. No. 5,576,070.
Issuance into two separate patents of this application and the
Reissue Continuation Application is thus being sought..Iaddend.
This application is a continuation of application Ser. No.
08/068,305 filed May 28, 1993, U.S. Pat. No. 5,281,450, which is
itself a continuation of application Ser. No. 07/890,855 filed on
Jun. 1, 1992, now abandoned.
Claims
I claim:
1. A method of fabricating a liquid crystal display subassembly,
said method comprising the steps of:
providing a substantially transparent substrate member;
disposing a layer of substantially opaque material upon one side of
said substrate, said substantially opaque material being a black
polyimide material;
forming at least one opening through said layer of substantially
opaque material;
disposing a light influencing material in said at least one
opening;
disposing a continuous layer of a transparent, passivating material
atop said layer of opaque material and said light influencing
material; and
disposing a layer of transparent, conductive material atop said
passivating layer.
2. A method as in claim 1, wherein the step of providing a
substantially transparent substrate member includes the further
step of selecting said member from the group of materials
consisting of glass, plastic, and combinations thereof.
3. A method as in claim 1, wherein the step of disposing a layer of
substantially opaque material upon said substrate includes the
further step of disposing said material to a thickness of between
0.10 and 100.0 .mu.m.
4. A method as in claim 3, wherein the opaque material is disposed
to a thickness of between 1.0 and 10.0 .mu.m.
5. A method as in claim 1, wherein the step of forming at least one
opening through said layer of substantially opaque material is
accomplished by employing a method selected from the group of a
high power laser, a photolithographic etch process, and
combinations thereof.
6. A method as in claim 5, wherein the step of forming at least one
opening includes the further steps of:
providing a high power excimer laser capable of at least micron
scale resolution;
placing said substrate with said layer of opaque material in close
proximity to said laser;
providing means for achieving relative movement between said laser
and said substrate; and
employing said laser to cut at least one opening in said layer of
opaque material.
7. A method as in claim 1, wherein the step of forming at least one
opening includes the further step of forming a plurality of
similarly sized and shaped openings, arranged in a densely packed,
uniformly spaced array.
8. A method as in claim 1, wherein the step of disposing a light
influencing material into said at least one opening includes the
further steps of:
providing a light influencing material in a non-solid phase having
the optical characteristics thereof optimized for a desired
application; injecting a sufficient amount of said light
influencing material into said openings so as to achieve a desired
light influencing effect; and
curing said non-solid light influencing material to the solid
phase.
9. A method as in claim 8, wherein the step of injecting light
influencing material into said openings includes the further steps
of:
providing at least one nozzle for injecting said materials, in
close proximity to one of said openings;
providing means for achieving relative movement between said nozzle
and said opaque material coated substrate, for disposing light
influencing material into preselected ones of said openings.
10. A method as in claim 9, wherein the step of curing said light
influencing material includes the further steps of:
providing infrared oven means; and
disposing said substrate, layer of opaque material, and light
influencing material into said oven means so as to solidify said
light influencing material.
11. A method as in claim 1, including the further step of selecting
a light influencing material adapted Lo color white light.
12. A method as in claim 11, wherein said light influencing
material is adapted to color light into the group of colors
consisting of red, green, blue, and combinations thereof.
13. A method of fabricating a liquid crystal display, said method
comprising the steps of:
providing a substantially transparent first substrate member;
disposing a layer of substantially opaque material upon one side of
said first substrate;
forming at least one opening through said layer of substantially
opaque material;
disposing a light influencing material in said at least one
opening;
disposing a continuous layer of a transparent, passivating material
atop said layer of opaque material and said light influencing
material;
disposing a layer of transparent, conductive material atop said
passivating layer;
providing a second substantially transparent substrate member
having a continuous layer of a transparent conductive material
disposed on one surface thereof, said second substrate being
spacedly disposed from said first substrate and arranged so that
the layer of transparent conductive material of the second
substrate faces the layer of transparent conductive material of the
first substrate; and
disposing a layer of liquid crystal material between said first and
said second substrates. .Iadd.
14. A method of fabricating a liquid crystal display, said method
comprising the steps of:
providing a substantially transparent first substrate member;
disposing a layer of substantially opaque material upon one side of
said first substrate;
forming at least three openings through said layer of substantially
opaque material;
injecting a light influencing material including first, second, and
third colors in said at least three openings directly on the first
substrate the first, second and third colors being injected
substantially simultaneously in the three openings,
respectively;
disposing a continuous layer of transparent, passivation material
atop said layer of opaque material and said light influencing
material, the continuous layer of transparent, passivation material
providing a substantially flat, level surface;
disposing a layer of transparent, conductive material atop said
substantially flat, level surface of the passivation layer;
providing a second substantially transparent substrate member
having a continuous layer of a transparent conductive material
disposed on one surface thereof, said second substrate being
spacedly disposed from said first substrate and arranged so that
the layer of transparent conductive material of the second
substrate faces the layer of transparent conductive material of the
first substrate; and
disposing a layer of liquid crystal material between said first and
second substrates. .Iaddend..Iadd.15. The method according to claim
14, wherein at least one of the first and second transparent
substrates includes a
plastic material. .Iaddend..Iadd.16. The method according to claim
14, wherein the openings are formed without using a
photolithography process. .Iaddend..Iadd.17. The method according
to claim 14, wherein the openings are optically formed.
.Iaddend..Iadd.18. The method according to claim 14, further
including the step of selecting a light influencing material
adapted to color white light. .Iaddend..Iadd.19. The method
according to claim 18, wherein said light influencing material is
adapted to color light into the group of colors consisting of red,
green, blue, and combinations thereof. .Iaddend..Iadd.20. A method
of fabricating a liquid crystal display, said method comprising the
steps of:
providing a substantially transparent first substrate member;
disposing a layer of substantially opaque material upon one side of
said first substrate;
forming an opening through said layer of substantially opaque
material, the opening having a first depth;
injecting a light influencing material in said opening directly on
the first substrate, the light influencing material filling the
opening to a level less than the first depth so as to prevent any
spill over of the light influencing material;
disposing a continuous layer of transparent, passivation material
atop said layer of opaque material and said light influencing
material, the continuous layer of transparent, passivation material
providing a substantially flat, level surface;
disposing a layer of transparent, conductive material atop said
substantially flat, level surface of the passivation layer;
providing a second substantially transparent substrate member
having a continuous layer of a transparent conductive material
disposed on one surface thereof, said second substrate being
spacedly disposed from said first substrate and arranged so that
the layer of transparent conductive material of the second
substrate faces the layer of transparent conductive material of the
first substrate; and
disposing a layer of liquid crystal material between said first and
second substrates. .Iaddend..Iadd.21. The method according to claim
20, wherein at least one of the first and second transparent
substrates includes a plastic material. .Iaddend..Iadd.22. The
method according to claim 20, wherein the openings are formed
without using a photolithography process. .Iaddend..Iadd.23. The
method according to claim 20, wherein the openings are optically
formed. .Iaddend..Iadd.24. The method according to claim 20,
further including the step of selecting a light influencing
material adapted to color white light. .Iaddend..Iadd.25. The
method according to claim 24, wherein said light influencing
material is adapted to color light into the group of colors
consisting of red, green, blue, and combinations thereof.
.Iaddend..Iadd.26. A method of fabricating a liquid crystal display
said method comprising the steps of:
providing a substantially transparent first substrate member;
disposing a layer of substantially opaque material upon one side of
said first substrate;
forming an opening through said layer of substantially opaque
material;
injecting a light influencing material in said opening;
disposing a layer of transparent conductive material over said
light influencing material;
providing a second substantially transparent substrate member
having a continuous layer of a transparent conductive material
disposed on one surface thereof, said second substrate being
spacedly disposed from said first substrate and arranged so that
the layer of transparent conductive material of the second
substrate faces the layer of transparent conductive material of the
first substrate; and
disposing a layer of liquid crystal material between said first and
second substrates;
wherein the method does not use a photolithography process to form
the opening in the light influencing material. .Iaddend..Iadd.27.
The method according to claim 26, wherein at least one of the first
and second
transparent substrates includes a plastic material.
.Iaddend..Iadd.28. The method according to claim 26, wherein the
openings are optically formed. .Iaddend..Iadd.29. The method
according to claim 26, wherein the light influencing material fills
the opening to a level less than a depth of the opening so as to
prevent any spill over of the light influencing material.
.Iaddend..Iadd.30. The method according to claim 26, further
including the step of selecting a light influencing material
adapted to color white light. .Iaddend..Iadd.31. The method
according to claim 30, wherein said light influencing material is
adapted to color light into the group of colors consisting of red,
green, blue, and combinations thereof. .Iaddend..Iadd.32. A method
of fabricating a liquid crystal display, said method comprising the
steps of:
providing a substantially transparent first substrate member;
disposing a layer of substantially opaque material upon one side of
said first substrate;
forming at least three openings through said layer of substantially
opaque material;
injecting a light influencing material including first, second, and
third colors in said at least three openings directly on the first
substrate;
disposing a continuous layer of transparent, passivation material
atop said layer of opaque material and said light influencing
material, the continuous layer of transparent, passivation material
providing a substantially flat, level surface; and
disposing a layer of transparent, conductive material atop said
substantially flat, level surface of the passivation layer.
.Iaddend..Iadd.33. The method according to claim 32, wherein the
openings are formed without using a photolithography process.
.Iaddend..Iadd.34. The method according to claim 32, wherein the
openings are optically formed. .Iaddend..Iadd.35. The method
according to claim 32, wherein the light influencing material fills
the opening to a level less than a depth of the opening so as to
prevent any spill over of the light influencing material.
.Iaddend..Iadd.36. The method according to claim 32, further
including the step of selecting a light influencing material
adapted to color white light. .Iaddend..Iadd.37. The method
according to claim 36, wherein said light influencing material is
adapted to color light into the group of colors consisting of red,
green, blue, and combinations thereof. .Iaddend.
Description
FIELD OF THE INVENTION
The present invention relates generally to the field of light
influencing elements for use in high resolution optical systems,
and particularly to a method of making such elements. The invention
more particularly relates to light influencing elements adapted to
act as a color filter for optical systems such as image scanning
systems and active or passive liquid crystal display devices. In
it's most specific form, the instant invention relates to high
resolution color filter elements, and methods of making the same,
which are adapted to all or pan of a liquid crystal display device,
such as an active matrix liquid crystal display, disposed
thereupon.
BACKGROUND OF THE INVENTION
Efficient production of full color systems for use in cameras,
television, etc. have been contemplated since at least as early as
the late 1950's and are generally discussed in an article which
appeared in the May 1959 edition of Scientific American. Reference
may also be made to U.S. Pat. Nos. 3,382,317, 3,443,023 and
3,443,025. As optical system technology evolved, so too did the
technology employed in providing full color thereto.
High resolution electronic optical systems, such as for example,
either active or passive liquid crystal displays, and contact image
scanning systems are today well known in the commercial fields.
While systems of the type described above have been generally
successful in fulfilling their intended purposes and have found
commercial acceptance, these systems exhibit several deficiencies.
The deficiency specifically addressed herein relates to the fact
that heretofore, the light influencing elements used in high
resolution optical systems, to, for example, polarize or color
filter light passing therethrough, have been very difficult to
fabricate, often requiring up to ten or more fabrication steps. The
result of having so many fabrication steps is that the
manufacturing process is very costly, and further that the process
is susceptible to producing high amounts of unacceptable or scrap
light influencing elements. This of course further increases the
cost of the light influencing elements.
As noted above, color liquid crystal display devices are well known
in the art, and one exemplary such device is set forth in U.S. Pat.
No. 4,632,514 to Ogawa et al, entitled "COLOR LIQUID CRYSTAL
DISPLAY APPARATUS". The '514 patent describes a color, twisted
nematic type display wherein the layer of liquid crystal material
is varied depending upon the color imparted to each picture element
of the display. Ogawa. et al describe the need to terrace the
layers of filter materials, which, as will be noted in greater
detail hereinbelow, require additional fabrication steps in the
manufacture of a display.
The commonly accepted method of fabricating light influencing
elements for high resolution optical systems, particularly liquid
crystal displays, is set forth in an article entitled Multicolored
Liquid Crystal Displays, published in Optical Engineering, Vol. 23
No. 3, May/June 1984. More particularly, FIG. 11 thereof
illustrates in a step-by-step manner, the conventional
photolithographic method of fabricating color filter elements for
liquid crystal display. As a perusal of said article teaches, a
color filter element is fabricated by depositing a layer of
transparent gelatine glue, known in the art as "fish glue" atop the
display electrodes, which have already been formed upon a
transparent substrate. A photomask is then applied so that the
transparent gelatine glue is removed from all ares other than atop
a display electrode. Thereafter, a layer of photoresist material is
disposed atop the entire device substrate and a photomask is
applied so that, assuming a red-green-blue color filter
arrangement, all electrodes and gelatine layers to be colored red
are exposed, while the electrodes to be colored blue or green
remain covered by photoresist. The exposed gelatine glue is then
dyed red and the dye is cured. Thereafter, the photoresist is
removed from the electrodes to be dyed green and blue, and a new
layer of photoresist is applied over the entire device substrate,
and a photomask is applied to expose the electrodes to be colored
blue. The exposed gelatine glue is then dyed blue and the dye is
cured. The same process is then repeated to provide the green dyed
electrodes.
An alternative, dry-etching technique is set forth in an article
entitled Fabrication of mosaic color filters by dry-etching
dielectric stacks, Journal of Vacuum Science Technology, A4(1),
Jan/Feb 1986. The approach is illustrated fully in FIG. 3 thereof,
which clearly illustrates the need to etch, mask and re-etch the
deposited materials in order to achieve the desired color
configuration. Moreover, this approach is limited to certain color
combinations and arrangements as two or more filter layers may be
needed to produce a single color.
A third commonly accepted method of providing color filter
materials is set forth in an article entitled Multicolor Graphic
LCD with tricolor layers formed by electrodeposition, and published
in the 1984 Society for Information Display Digest. In this
article, the authors set forth an electrodeposition method for
depositing and patterning color filter layers. In this method,
certain electrode layers were activated so as to cause dyed
pigments to be electrochemically deposited thereupon. Thereafter, a
second set of electrodes is activated so that a second color can be
deposited, and so on for all subsequent colors to be deposited.
While this method does not require the deposition and patterning of
filter material layers, it does require the deposition and
patterning of electrode layers, and the subsequent
electrodeposition steps for each color.
In addition to the deficiencies inherent in the multistep
deposition/etch processes discussed hereinabove, none of such
methods of fabricating a
light influencing element provide a light barrier around each color
filter so as to eliminate the presence of stray, non-filtered
light. Such stray, non-filtered light has the effect of washing out
the color of the light that is being transmitted through the color
filter. The result is that the color image looses sharpness and
intensity. A light blocking layer around color filters or display
picture elements is commonly called a black matrix in the field.
The provision of a black matrix has heretofore involved the
subsequent deposition of a light blocking layer of material around
the filters or the picture elements after such elements have been
formed. The result is the need to provide additional photoresist
deposition, mask and etch steps in order to provide the black
matrix, with the most often result being greater expense
attributable to more costly processing and greater losses cause by
the manufacturing process itself.
These and other limitations of the prior art are obviated by the
invention disclosed and claimed herein.
BRIEF DESCRIPTION OF THE INVENTION
It is an object of the present invention to provide a light
influencing element for high resolution electronic optical systems,
and a method of fabricating the same which avoids the need to
employ repeated photolithographic steps.
It is a further object of the instant invention to provide a light
influencing element which also includes a black matrix layer for
improving the contrast, resolution and sharpness of optically
enhanced light passing therethrough.
It is a further object of the instant invention to provide liquid
crystal display devices and subassemblies thereof which may be
fabricated upon the light influencing element of the instant
invention.
These and other objects are achieved by fabricating light
influencing elements which by a comprising the steps of: providing
a substantially transparent substrate member; disposing a layer of
a substantially opaque material upon one side of said substrate;
forming at least one opening through said layer of substantially
opaque material; and disposing a light influencing material in said
at least one opening. The substantially transparent substrate
member is typically selected from the group of materials consisting
of glass, plastic and combinations thereof.
The layer of substantially opaque material is disposed to a
thickness of between 0.10 and 100.0 .mu.m, and preferably between
1.0 and 10.0 .mu.m. This opaque material may be fabricated from a
deposit of materials such as a polymeric material, metallic
materials, semiconductor materials and combinations thereof, though
in a preferred embodiment, the material is a black polyimide
material.
One or more openings or wells are formed through said layer of
substantially opaque material. The formation of such openings is
accomplished by employing a method such as a high power laser, or a
photolithographic etch process to cut or eat away the opaque
material. When the embodiment of a laser is employed, a high power
excimer laser capable of at least micron scale resolution is
required to be placed in close proximity to said substrate and
layer of opaque material. Depending upon the application desired
for the light influencing element, a plurality of similarly sized
and shaped vias arranged in a densely packed, uniformly spaced
M.times.N array may be provided. Alternatively, the array of vias
may be arranged into a series of interlocking triangles or
"triads", or elongated stripes.
Into the opening or openings is disposed a light influencing
materials as by providing a light influencing material in non-solid
phase having the optical characteristics thereof optimized for the
desired application, which material is injected in a sufficient
amount so as to achieve a desired light influencing effect.
Thereafter, the material is curing from the non-solid to the solid
phase.
In one embodiment, the light influencing element is adapted to
function as a color filter element for a liquid crystal display or
a subassembly thereof. In this application, the light influencing
material is adapted to color white light into the group of colors
consisting of red, green, blue and combinations thereof.
These and other objects and advantages of the subject invention
will become apparent from a perusal of the detailed description of
the invention, the drawings and the claims which follow.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 illustrates in perspective view, the light influencing
element of the instant invention;
FIGS. 2A, 2B and 2C illustrate, in a partial cross-sectional side
view taken along line 2--2 of FIG. 1, the inventive method of
fabricating the light influencing element of FIG. 1;
FIGS. 3A, 3B and 3C illustrate in cross-sectional, partial side
view, the processing steps involved in fabricating a liquid crystal
display subassembly, from the light influencing element of FIGS. 1
and 2; and
FIG. 4 illustrates in cross-sectional, partial side view the
processing steps required in order to fabricate a liquid crystal
display from the liquid crystal subassembly and light influencing
element of FIGS. 1, 2 and 3.
DETAILED DESCRIPTION OF THE INVENTION
A. Light Influencing Element
Referring now to FIG. 1, there is illustrated therein, in
perspective view, the light influencing element of the instant
invention, identified generally by the reference numeral 10. The
light influencing element 10 will typically be employed as a color
filter element, as is explained in greater detail hereinbelow,
though it is to be understood that such an element may be employed
in a number of different applications including, but not limited
to, a light diffuser, a light collimator, a light polarizer or a
light rotating element. Alternatively, the light influencing
element may be adapted to provide an optical effect upon radiation
not in the range of visible light. Hence, said element may be
adapted to filter certain wavelengths of radiation such as
infra-red or ultra violet.
The light influencing element 10 includes a transparent substrate
12, which serves as the base upon which subsequent structures are
formed. The substantially transparent substrate 12, is typically
fabricated from a device quality, high temperature sheet of glass,
which is free from defects and optical inclusions. Alternatively,
the substrate may be formed from other substantially transparent
materials such as a clear plastic or other polymeric material which
may be either rigid, as glass, or flexible as would be the case for
a thin, polymeric material such as a layer of kapton, or
polycarbonate materials of the type that are currently used in
numerous applications wherein considerations such as hardness and
optical clarity are of paramount importance.
Disposed upon said substrate 12 is a layer of substantially opaque
material 14. The layer of substantially opaque material 14 may
typically be formed of a polymeric material such as a black
polyimide material deposited to a thickness of between 0.10 and
100.0 .mu.m, and preferably between 1.0 and 10.0 .mu.m.
Alternatively, the layer of substantially opaque material 14 may be
formed of a metallic material, such as, but not limited to, tin,
chromium, molybdenum or tantalum deposited to a thickness
sufficient to substantially prevent the transmission of light
therethrough. The layer of substantially opaque material 14 may
otherwise be formed from a layer of a non-metallic, and
non-polymeric material, such as a layer of amorphous silicon or an
amorphous silicon alloy material, again deposited to a thickness
sufficient to prevent the transmission of light therethrough. In
one preferred embodiment, the layer of substantially opaque
material is a layer of black polyimide material deposited to a
depth of between 1.0 and 10.0 .mu.m.
Formed in said layer of substantially opaque material 14 is at
least one opening 16 which extends through said layer 14 to the
substrate 12. The number and spacing of the at least one opening,
in the event that there are more than one, will depend upon the
ultimate application in which the light influencing element is to
be used employed. For example, if the clement 10 is to be used as a
color filter in a liquid crystal display, then the size, packing
density, number and pitch of the picture elements (or pixels) of
the display will determine the size, packing density, number and
pitch of the openings 16 in the light influencing clement 10.
Alternatively, the openings may be formed as one or more elongated
strips in the layer of substantially opaque material.
The openings 16 themselves may be formed by any one of a number of
techniques, such as a conventional photolithographic and etch
technique. In one preferred embodiment of the method of the instant
invention, which is described in greater detail hereinbelow, the
openings 16 are formed by employing a high resolution i.e., capable
of at least micron scale resolution, high power laser device, such
as an excimer laser adapted to cut a plurality of similarly sized
and shaped openings in the layer of substantially opaque material
14. The element 10 of FIG. 1 may be adapted, as mentioned above to
use in conjunction with a liquid crystal display. Hence, the
excimer laser should be able to form a plurality of openings 16
formed in a highly packed N.times.M matrix of rows and columns. In
FIG. 1, the element 10 is arranged as a matrix of 3.times.3
openings, though it is to be understood that the element 10 may be
arranged to include any number of openings arranged in rows and
columns, or in any other fashion, such as a series of interlocking
triangles or "triads", or elongated stripes.
Disposed in each of the openings 16 is a light influencing material
selected to provide a desired optical effect. For example, if the
light influencing material is to be employed as a color filter
element, dye, ink such as the ink used in so-called ink-jet
technology or other color pigments may be disposed in said openings
16. The dyes or pigments, which may be either of the additive or
subtractive variety, would be disposed in a manner and to a
thickness sufficient to, for example, color white light red as it
passed therethrough. Having appropriately prepared the light
influencing element 10 so as to provide a desired optical effect,
the element 10 may then be adapted to serve as the foundation upon
which an entire electronic optical device, or some subassembly
thereof, is fabricated.
Turning now to FIGS. 2A, 2B and 2C, there is illustrated therein,
in a partial cross-sectional side view taken along line 2--2 of
FIG. 1, a light influencing element fabricated according to the
instant invention. More particularly, FIG. 2A illustrates the
substrate 12, having a layer of substantially opaque material 14
deposited on one surface thereof. As noted hereinabove, the
substantially opaque material 14 may be fabricated of a metal,
semiconductor or a polymeric material, though in one preferred
embodiment, the layer of substantially opaque material 14 is a
layer of black polyimide material, deposited by, for example, spin
coating or blade application, to a depth of between 1.0 and 10.0
.mu.m, so as to prevent the passage of light therethrough.
Referring now to FIG. 2B, the substrate 12 and layer of opaque
material 14 are placed in relatively close proximity to and arc
exposed to a high power, high resolution laser device such as an
excimer laser 100. The high power, high resolution laser 100 is
employed to form, as by cutting, at least one opening in the layer
of opaque material 14. In FIG. 2B, the laser has formed six (6)
openings 16a, 16b, 16c, 16d, 16e and 16f in layer 14. The excimer
laser 100 must be capable of at least micron resolution, and thus
should be able to form a plurality of openings in a highly packed
N.times.M matrix of rows and columns. In FIG. 1, the element 10 is
arranged as a matrix of 3.times.3 openings of which FIG. 2
illustrates but six openings in a row of 8, though it is to be
understood that the element 10 may be arranged to include any
number of openings arranged in rows and columns, or in any other
fashion, such as triads or stripes.
In order to form more than one opening in the layer of opaque
material 14, it is necessary to effect some type of relative
movement between the substrate and the laser. As the laser is
capable of very high resolutions, the tolerances for any movement
must be very precise so as to not upset the resolution and
patterning of the openings. It is therefore necessary to provide a
precise raster-type or other conventionally known step and repeat
type device for scanning the laser across the surface of the
substrate 12 and layer 14. Alternatively, the substrate 12 and
layer 14 may be scanned across a stationary laser source 100.
Turning now to FIG. 2C, the substrate 12 with the layer of opaque
material 14 having a plurality of openings 16a-16f formed therein
is placed in relatively close proximity to means for injecting a
light influencing material into said openings. Further, in one
preferred embodiment of the invention, these injection means
comprise three injection nozzles 21a, 21b, and 21c which are
adapted to inject, for example, dye, ink or color pigments into the
openings 16a-16f, in so called "ink-jet" fashion. The nozzles
21a-21c or the substrate 12 may either be fitted with apparatus to
effect relative movement therebetween so that one or more nozzles
may be used to fill each opening. Hence, in the application wherein
the light influencing element 10 of FIG. 1 is a color filter
element having red, green and blue filters, nozzle 21a may be
adapted to inject red dye, ink or pigment into opening 16a to
create red filter 18a, nozzle 21b may be adapted to inject blue
dye, ink or pigment into opening 16b to create blue filter 20a, and
nozzle 21c may be adapted to inject green dye, ink or pigment into
opening 16c to create green filter 22a. Thereafter, either the
substrate 12 or the nozzles 21a-21c may be moved over to the next
untilled openings 16d-16f, wherein nozzle 21a injects red dye, ink
or pigment into opening 16d to create red filter 18b, nozzle 21b
injects blue dye, ink or pigment into opening 16e to create blue
filter 20b, and nozzle 21c injects green dye, ink or pigment into
opening 16f to create green filter 22b. This step and repeat
process is continued until all of the openings have been
filled.
The light influencing material disposed in each opening can be any
one of several materials which are initially in a non-solid state,
i.e, a liquid, an aqueous solution, a suspension, an emulsion or
even a rapidly condensing gas. The non-solid material will possess
the optical characteristics necessary to accomplish a desired task
such as polarization or color filtering of light passing
therethrough Moreover, the physical characteristics of the
material, such as viscosity, color coordinates, etc. are to be
optimized for a desired application and performance when injected
in ink-jet fashion from nozzles 21a-21c. Preferred materials to be
used in the openings of the light influencing element 10, include
ink, dyes or pigmented inks, gelatins, organic materials and water
soluble materials and such other materials that can be made
susceptible to injection as by ink-jet technology.
After injecting said non-solid light influencing materials into
said openings 16a-16f, it is necessary to cure said injected
materials to the solid state. This may be accomplished by any one
of a number of means ranging from allowing the materials to harden
by exposure to ambient conditions, to placing the substrate and
materials disposed thereon into an oven, such as an autoclave or
infra-red oven, and exposing said materials to those conditions
until cured to the solid state. In this manner, it is possible to
fabricate a light influencing element, such as a color filter for
use in conjunction with a high resolution liquid crystal display
device, without encountering the limitations of the prior art
methods.
B. Liquid Crystal Subassembly
A liquid crystal display subassembly may be obtained by employing
the light influencing element 10 of FIGS. 1 and 2. More
particularly, FIGS. 3A, 3B and 3C illustrate in cross-sectional,
partial side view, the processing steps involved in fabricating a
liquid crystal display subassembly, such as the so-called passive
plate, from the light influencing element of FIGS. 1 and 2. The
subassembly, fully illustrated in FIG. 3C as 300, is fabricated by
disposing a continuous layer of a transparent, passivating material
26 atop the color filters 18a, 18b, 20a, 20b, 22a and 22b and black
polyimide layer 14 of the light influencing element 10 of FIGS. 1
and 2. The passivating material 26 is adapted to, and must be is
deposited
to a depth sufficient to perform at least two critical functions:
1) to level the underlying filter and opaque layers to a
continuous, flat surface to serve as a base upon which subsequent
layers may be formed; 2) to electrically insulate the light
influencing element 10 from any electrically conductive layers that
may be disposed upon the passivating layer; and 3) to provide a
flat, level surface so as to assure a uniform thickness for any
layer of liquid crystal material disposed thereon. As light must be
able to pass through the element and subassembly, it is necessary
for the passivating layer 26 to be formed from a layer of material
that is also transparent. In one preferred embodiment of the
instant invention, the transparent, insulating, passivating
material 26 is formed from a transparent, organic material such as
a transparent resin, SiN, SiO, polyimides and combinations
thereof.
Thereafter, a layer of a transparent, conductive material, such as
a transparent conductive oxide material 30 of FIG. 3B, is disposed
upon the passivation layer 26. Preferred transparent conductive
oxides include indium oxide, tin oxide, indium tin oxide, cadmium
sulfate and combinations thereof. Thereafter, employing
photolithographic techniques well know in the an, the layer of
transparent conductive material 30 is patterned to form a plurality
of electrodes 32a-32f, which electrodes are formed directly above
the openings 16a-16f, which define color filters 18a, 18b, 20a,
20b, 22a and 22b, though are separated therefrom by the passivation
layer 26. Alternatively, the layer of transparent conductive
material 30 may be left unpatterned to achieve a so-called common
electrode. Accordingly, the subassembly 300 would include a
plurality of aligned color filters and electrodes arranged in an
N.times.M matrix array. In this way, it is possible to fabricate a
liquid crystal display subassembly which avoids the limitations
inherent in the prior art.
C. Liquid Crystal Display Device
A liquid crystal display device may be obtained by employing the
liquid crystal subassembly of FIGS. 3A, 3B and 3C. More
particularly, FIG. 4 illustrates in cross-sectional, partial side
view the processing steps required in order to fabricate a liquid
crystal display 400 from the liquid crystal subassembly 300 and
light influencing element 10 of the instant invention. The liquid
crystal subassembly 300 is employed to fabricate a liquid crystal
display by providing a second substrate 40, which substrate 40 is
typically fabricated from a device quality, high temperature sheet
of glass, which is free from defects and optical inclusions.
Alternatively, the substrate 40 may be formed from other
substantially transparent materials such as a clear plastic or
other polymeric material which may be either rigid, as glass, or
flexible as would be the case for a thin, polymeric material such
as a layer of kapton, or polycarbonate materials of the type that
are currently used in numerous applications wherein considerations
such as hardness and optical clarity are of paramount
importance.
The second substrate 40 has disposed thereupon a layer of
transparent conductive material such as a transparent conductive
oxide material 42. Preferred transparent conductive oxides include
indium oxide, tin oxide, indium tin oxide cadmium sulfate and
combinations thereof. The layer of transparent conductive material
42 may be either a continuous layer or may be a patterned layer of
display electrodes formed by conventional photolithographic
processes. The second substrate 40 may also have disposed thereon
other micro-electronic devices such as transistors or diodes which
enhance the switching and other performance of the display. The
second substrate 40 is arranged so that the second layer of
transparent conductive material 42 is spacedly disposed from and
facing the patterned layer of transparent conductive material
disposed on the first substrate 12. A layer of liquid crystal
material, such as a twisted nematic, cholesteric or other liquid
crystal is disposed between said first and second substrate 12 and
40, which layer of material will effect a change in optical
characteristic from transparent to opaque upon application of an
electrical charge thereto. By employing the light influencing
element of FIGS. 1 and 2 as a color filter element upon which a
liquid crystal display is fabricated as described herein, it is
possible to achieve a full color liquid crystal display device free
from the processing limitations inherent in the prior art.
As may be readily appreciated by those skilled in the art, the
present invention can be practiced other than as is specifically
disclosed herein. Thus, while the instant invention has been
described with respect to certain preferred embodiments thereof, it
is to be understood that the foregoing and other modifications and
variations may be made without departing from the spirit or scope
thereof.
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