U.S. patent application number 11/856916 was filed with the patent office on 2008-03-20 for liquid crystal display element.
This patent application is currently assigned to FUJITSU LIMITED. Invention is credited to Masaki NOSE, Tomohisa SHINGAI, Junji TOMITA.
Application Number | 20080068553 11/856916 |
Document ID | / |
Family ID | 37023410 |
Filed Date | 2008-03-20 |
United States Patent
Application |
20080068553 |
Kind Code |
A1 |
TOMITA; Junji ; et
al. |
March 20, 2008 |
LIQUID CRYSTAL DISPLAY ELEMENT
Abstract
A liquid crystal layer sandwiched by a lower substrate 1 and an
upper substrate comprises cross-shaped supports, a wall surface
structure, and a seal member. The supports 15 are provided at the
four sides of each pixel. Contiguous pixels are linked via openings
between supports. The wall surface structure is provided in the
periphery of the supports arranged in the form of a grid. The
supports and the wall surface structure are a same member having
adhesiveness. A portion of the wall surface structure is an inlet
of liquid crystal. A seal member is provided at the perimeter of
the wall surface structure 17. The liquid crystal poured from the
inlet is poured into all of pixels via openings. A black matrix in
the form of a grid, which covers the top side of all of the
supports, is provided on the upper substrate.
Inventors: |
TOMITA; Junji; (Kawasaki,
JP) ; NOSE; Masaki; (Kawasaki, JP) ; SHINGAI;
Tomohisa; (Kawasaki, JP) |
Correspondence
Address: |
WESTERMAN, HATTORI, DANIELS & ADRIAN, LLP
1250 CONNECTICUT AVENUE, NW
SUITE 700
WASHINGTON
DC
20036
US
|
Assignee: |
FUJITSU LIMITED
1-1, Kamikodanaka 4-chome, Nakahara-ku,
Kawasaki-shi
JP
211-8588
|
Family ID: |
37023410 |
Appl. No.: |
11/856916 |
Filed: |
September 18, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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PCT/JP2005/004925 |
Mar 18, 2005 |
|
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11856916 |
Sep 18, 2007 |
|
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Current U.S.
Class: |
349/153 |
Current CPC
Class: |
G02F 1/134327 20130101;
G02F 1/133305 20130101; G02F 1/13718 20130101; G02F 1/13394
20130101; G02F 1/1341 20130101; G02F 1/133512 20130101 |
Class at
Publication: |
349/153 |
International
Class: |
G02F 1/1339 20060101
G02F001/1339 |
Claims
1. A liquid crystal display unit comprising: a first substrate on
which a first electrode is arranged; a second substrate on which a
second electrode is arranged; a liquid crystal layer provided
between the first substrate and the second substrate and having a
plurality of pixels; and a first wall surface structure arranged
along each side of said each pixels; wherein the first wall surface
structure has at least two openings which link contiguous pixels in
the first wall surface structure, and has a width narrower than
that of the first wall surface structure.
2. The liquid crystal display element according to claim 1, wherein
a cross-section of the first wall surface structures is
cross-shaped.
3. The liquid crystal display element according to claim 1, wherein
the plurality of pixels are rectangular.
4. The liquid crystal display element according to claim 1, wherein
the openings are formed on sides of the first wall surface
structures.
5. The liquid crystal display element according to claim 1, wherein
the openings are arranged nonlinearly in a column electrode
direction or a row electrode direction.
6. The liquid crystal display element according to claim 1, wherein
the openings are arranged nonlinearly in a column electrode
direction and a row electrode direction.
7. The liquid crystal display element according to claim 1 further
comprising a second wall surface structure that is comprised to
enclose the first wall surface structures.
8. The liquid crystal display element according to claim 1, wherein
part of the first wall surface structures contacts the first or the
second electrode.
9. A liquid crystal display unit comprising: a first substrate on
which a first electrode is arranged; a second substrate on which a
second electrode is arranged; a liquid crystal layer provided
between the first substrate and the second substrate and having a
plurality of pixels; and a first wall surface structure arranged
along each side of said each pixels; wherein the first wall surface
structure has at least two openings which link contiguous pixels in
the first wall surface structure, and has a width narrower than
that of the first wall surface structure.
10. The liquid crystal display element according to claim 9,
wherein the first wall surface structures have at least two
openings that link contiguous pixels.
11. The liquid crystal display element according to claim 9,
wherein a cross-section of the first wall surface structures is
cross-shaped.
12. The liquid crystal display element according to claim 9,
wherein the plurality of pixels are rectangular.
13. The liquid crystal display element according to claim 10,
wherein the openings are formed on sides of the first wall surface
structures.
14. The liquid crystal display element according to claim 10,
wherein the openings are arranged nonlinearly in a column electrode
direction or a row electrode direction.
15. The liquid crystal display element according to claim 10,
wherein the openings are arranged nonlinearly in a column electrode
direction and a row electrode direction.
16. The liquid crystal display element according to claim 9,
further comprising a second wall surface structure that is
comprised to enclose the first wall surface structures.
17. A liquid crystal display unit comprising: a first substrate on
which a first electrode is arranged; a second substrate on which a
second electrode is arranged; a liquid crystal layer provided
between the first substrate and the second substrate and having a
plurality of pixels; and a first wall surface structure arranged
along each side of said each pixels; wherein the first wall surface
structure has at least two openings which link contiguous pixels in
the first wall surface structure, and has a width narrower than
that of the first wall surface structure.
18. The liquid crystal display element according to claim 17,
wherein liquid crystal within a pixel enclosed by the first wall
surface structures in the liquid crystal layer is dripped.
19. The liquid crystal display element according to claim 17,
wherein a seal member is arranged at an outer perimeter of the
second wall surface structure.
20. The liquid crystal display element according to claim 17,
wherein liquid crystal poured into the liquid crystal layer is
poured only into a region enclosed by the second wall surface
structure.
21. The liquid crystal display element according to claim 17,
wherein a seal member is not arranged at the outer perimeter of the
second wall surface structure.
22. The liquid crystal display element according to claim 17,
wherein the first and the second substrates are adhered and secured
by the first and the second wall surface structures.
23. The liquid crystal display element according to claim 1,
wherein a black matrix for shielding light is not comprised.
24. The liquid crystal display element according to claim 1,
wherein liquid crystal of the liquid crystal layer is liquid
crystal having a memory property.
25. The liquid crystal display element according to claim 24,
wherein the liquid crystal having the memory property is
cholesteric liquid crystal.
26. A color liquid crystal display element comprising: the liquid
crystal display elements according to claim 1 that is stacked by a
plural number.
27. The color liquid crystal display element according to claim 26,
wherein the liquid crystal display element in an uppermost layer
displays a blue color.
28. An electronic information appliance equipped with the liquid
crystal display element according to claim 1.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is a continuation of PCT application of
PCT/JP2005/004925, which was filed Mar. 18, 2005.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a liquid crystal display
element of dot matrix system, and more particularly, to a liquid
crystal display element that is superior in flexibility.
[0004] 2. Description of the Related Art
[0005] In the future, electronic paper that can hold a display
without a power supply and can electrically rewrite contents of the
display is expected to become rapidly widespread. Electronic paper
implements a book, a magazine, newspaper, etc., which are
conventionally paper printed matters, by using an apparatus that
can electrically rewrite a display, and has superior
characteristics of paper printed matters, such as thinness,
lightweight, and easiness to look. Electronic paper is superior to
paper printed matters in a point that contents of a display can be
rewritten. Accordingly, electronic paper is not discarded like
paper printed matters. Therefore, electronic paper greatly
contributes to reductions in the consumption of paper resources if
it becomes widespread as an alternative to paper printed matters.
This is considered to be very useful also from the viewpoint of
environmental protection.
[0006] As applications of electronic paper, an electronic book, an
electronic newspaper, an electronic poster, an electronic
dictionary, etc. are considered. As characteristics demanded for
electronic paper, the following (1) to (5) and the like exist.
(1) electrical rewritability of display data
(2) ultra-low consumption power
(3) easy on the eyes, and difficult to be tired (very easy to
look)
(4) easy to carry (lightweight and easy to tote)
(5) as thin as paper and bendable (lightweight and flexible)
[0007] Electronic paper has been studied and developed by using an
electrophoresis system, a twist ball system, a liquid crystal
display, an organic EL(electro-luminessance) display, etc.
[0008] The electrophoresis system is a system for moving charged
particles in the air or a liquid. The twist ball system is a system
for rotating two-color-coded charged particles. The organic EL
display (organic electro-luminescence display) is a self-luminous
display unit having a structure where a plurality of thin films
made of an organic material are sandwiched by negative and positive
electrodes. The liquid crystal display is a non-self-luminous
display unit having a structure where a liquid crystal layer is
sandwiched by a pixel electrode and an opposed electrode.
[0009] Electronic paper implemented with the liquid crystal display
has been studied and developed by using cholesteric liquid crystal
of selective reflection type having bistability. Here, the
bistability is a nature that a liquid crystal exhibits stability in
two different alignment states, and the cholesteric liquid crystal
has a nature that two stable states such as planar and focal conic
states are maintained for a long time even after an electric field
is removed. For the cholesteric liquid crystal, incident light is
interfered and reflected in the planar state, whereas incident
light is transmitted in the focal conic state. Accordingly, a
liquid crystal panel using the cholesteric liquid crystal as a
liquid crystal layer, the lightness/darkness of light can be
displayed with the selective reflection of incident light in the
liquid crystal layer. This eliminates the need for a polarization
plate. The cholesteric liquid crystal is also called chiral nematic
liquid crystal.
[0010] Since the cholesteric liquid crystal reflects a color with
the interference of liquid crystal, a color display can be made
only by stacking the liquid crystals. Therefore, a liquid crystal
display system using the cholesteric liquid crystal (here, referred
to as a cholesteric liquid crystal system for the sake of
convenience) is overwhelmingly superior in a color display to other
systems such as the above described electrophoresis system, etc.
With the other systems, color filters tinted in three colors must
be arranged for each pixel. Therefore, its brightness is one-third
of the cholesteric liquid crystal system. Accordingly, for the
other systems, improving the brightness is a significant challenge
to implement electronic paper.
[0011] As described above, the cholesteric liquid crystal has an
advantage that a color display is easy, but its most significant
challenge is to impart flexibility, which is the characteristic of
electronic paper.
[0012] For a liquid crystal display element, a uniform cell of a
gap of several .mu.m is required. Normally, a cell is formed by
sandwiching a liquid crystal layer (several .mu.m) between upper
and lower glass substrates. For a normal liquid crystal panel of TN
(Twisted Nematic) type or STN (Super Twisted Nematic) type, also
some liquid crystal display element (plastic liquid crystal) using
a film substrate made of transparent special resin is implemented.
The plastic liquid crystal element can be reduced in thickness and
weight compared with the liquid crystal of a glass substrate, and
also has high endurance and a high strength against bending.
Accordingly, the plastic liquid crystal is freely bendable like
paper, and suitable for electronic paper.
[0013] Here, a conventional configuration for implementing a
uniform cell gap of a liquid crystal panel is described.
[0014] FIG. 1 is an exploded view of the cell structure of a liquid
crystal display element of a dot matrix structure, which implements
a uniform cell gap by using a support spacer.
[0015] The liquid crystal display element shown in this figure has
a structure where a liquid crystal layer is sandwiched between a
first substrate (lower substrate) 1 and a second substrate (upper
substrate) 2. The liquid crystal layer is composed of a seal member
3, adhesive supports 5, etc. On the surface of the first substrate
1, a plurality of transparent column electrodes (not shown) are
formed. Additionally, on the back of the second substrate 2, a
plurality of transparent row electrodes (not shown), which
vertically intersect the column electrodes, are formed. On the side
of the liquid crystal layer on the first substrate 1 on which the
column electrodes are formed, the seal member 3 is formed.
[0016] The seal member 3 is an adhesive of thermal hardening type
or UV(ultraviolet) hardening type manufactured in a printing
process, and configures the periphery of the liquid crystal layer.
In the center of one side 3a of the seal member 3, an opening is
provided, and both of its ends extend to form an inlet 4 of liquid
crystal. Namely, a portion of the seal member 3 is the inlet 4 of
the liquid crystal, via which the liquid crystal is poured into a
region enclosed by the seal member 3.
[0017] Within the region enclosed by the seal member 3, a plurality
of adhesive supports 5, which serve as spacers of the liquid
crystal layer, are formed. These adhesive supports 5 are formed at
the four corners of each pixel of the liquid crystal layer.
[0018] The adhesive supports 5 are members that take the shape of a
cylinder, and can be bonded to the second substrate 2. Therefore,
if the first substrate 1, on which the seal member 3 and the
adhesive supports 5 are formed, and the second substrate 2 are
stacked, the first substrate 1 and the second substrate 2 are
adhered with the seal member 3 and the adhesive supports 4. The
seal member 3 is, for example, a member that is hardened by being
heated.
[0019] With the liquid crystal display element having the above
described configuration using the cholestric liquid crystal of
selective reflection type for the liquid crystal layer, a portion
between pixels, in which an electrode is not provided in an upper
or lower opposed position, stays lit up. Therefore, to improve the
contrast of a pixel by preventing the portion from staying lit up,
a black matrix 6 is formed on the second substrate 2. This black
matrix 6 is a grid-shaped pattern corresponding to portions (four
sides of a pixel) of a liquid crystal layer, in which an electrode
(row or column electrode) is not arranged downward or upward.
[0020] In the liquid crystal display element having the above
described configuration, the adhesive supports 5 serve as spacers,
whereby a width (cell gap) between the first substrate 1 and the
second substrate 2 is kept uniform.
[0021] A support like the adhesive support 5 can be formed, for
example, with patterning using a photolithography disclosed by
Japanese Unexamined Utility Model Application Publication No.
58-13515, or Japanese Unexamined Patent Application Publication No.
H8-76131.
[0022] In the liquid crystal display element having the above
described configuration, cholesteric liquid crystal is poured from
the inlet 4, whereby a cholesteric liquid crystal display element
of selective reflection type can be implemented. However, to the
cholesteric liquid crystal display element of selective reflection
type, flexibility cannot be imparted only by implementing a uniform
cell gap.
[0023] Because liquid crystal is a liquid, it flows by force
applied by operations such as bending of a liquid crystal panel, or
pressing of its display surface, and a display state varies. Since
the display of the liquid crystal panel of TN type or STN type
continues to be electrically driven, its display state can
immediately revert to the original state even if it varies.
However, for the cholesteric liquid crystal having the memory
property of a display, its display does not revert to the original
state until it is again driven.
[0024] A method for forming a support like the adhesive support 5
shown in FIG. 5 in the cholesteric liquid crystal display element
is disclosed, for example, by Japanese Published Unexamined Patent
Application Publication No. 2000-146527. The invention disclosed by
this publication mainly aims at ensuring the uniformity of cell
gaps, and does not aim at holding the memory property of a
cholesteric liquid crystal display element when a liquid crystal
panel is bent or its display surface is pressed.
[0025] To apply the cholesteric liquid crystal of selective
reflection type to electronic paper, implementing a structure with
which a display does not vary even if electronic paper is pressed
or bent was the greatest challenge.
[0026] As a result of creating a liquid crystal cell having the
support structure shown in FIG. 1 with a film substrate of 0.125
.mu.m, its display varied only by being held by hand. To prevent
the display from varying, a robust housing was required for the
support structure of the liquid crystal cell, and it was impossible
to apply this liquid crystal cell to electronic paper having
flexibility.
[0027] The present inventor ascertained the mechanism, with which
the display of a liquid crystal cell using cholesteric liquid
crystal having a conventional support structure varies with the
pressing force of its display surface, by experiment. This
mechanism is disclosed by PCT Application No. PCT/JP2004/013380
previously filed by the present inventor.
[0028] The cause of the above described display variance is the
fluidity of liquid crystal (cholesteric liquid crystal), which is
resultant from pressing force applied to a display surface, or the
bending of a liquid crystal cell, and the problem of the display
variance can be solved by suppressing this fluidity. A spacer
structure using a cylinder or a square support cannot suppress the
fluidity of liquid crystal. Also a support having a stripe
structure for the uniformity of cell gaps is proposed. With this
structure, however, liquid crystal easily flows.
SUMMARY OF THE INVENTION
[0029] According to one aspect of the present invention, there is
provided a liquid crystal display unit having a first substrate
being arranged a first electrode on the first substrate; a second
substrate being arranged a second electrode on the second
substrate; a liquid crystal layer being configured between the
first substrate and the second substrate; a plurality of pixels
being provided in the liquid crystal display; a first wall surface
structure being arranged on a side face of each side of said each
pixels; and a openings having at least two openings that link
contiguous pixels in the first wall surface structure, being narrow
than a width of the first wall surface structure.
[0030] According to one aspect of the present invention, there is
provided a liquid crystal display unit having a first substrate
being arranged a first electrode on the first substrate; a second
substrate being arranged a second electrode on the second
substrate; a liquid crystal layer being configured between the
first substrate and the second substrate; a plurality of pixels
being provided in the liquid crystal display; and a first wall
surface structure being arranged on a side face of each side of
said each pixels; wherein a part of the first wall surface
structure connects the first electrode or the second electrode.
[0031] According to one aspect of the present invention, there is
provided a liquid crystal display unit having a first substrate
being arranged a first electrode on the first substrate; a second
substrate being arranged a second electrode on the second
substrate; a liquid crystal layer being configured between the
first substrate and the second substrate; a plurality of pixels
being provided in the liquid crystal display; a first wall surface
structure being arranged on a side face of each side of said each
pixels; and a second wall surface structure being arranged to
surrounding of the first wall surface structure; wherein the first
wall surface structure encloses all of side faces of said each
pixels.
BRIEF DESCRIPTION OF DRAWINGS
[0032] FIG. 1 is an exploded view showing a cell structure of a
liquid crystal display element of a conventional dot matrix
structure, which implements a uniform cell gap by using a support
spacer.
[0033] FIG. 2 is an exploded view showing the entire configuration
of a liquid crystal display element according to a preferred
embodiment of the present invention.
[0034] FIG. 3 is a schematic showing the arrangement configuration
of supports in the liquid crystal display element according to the
preferred embodiment.
[0035] FIG. 4 shows the arrangement configuration of openings of a
pixel, which are provided between supports, in the liquid crystal
display element according to the preferred embodiment.
[0036] FIG. 5 shows the arrangement pattern of supports in a liquid
crystal layer in an implementation example 1 of the liquid crystal
display element according to the preferred embodiment.
[0037] FIG. 6 shows the arrangement pattern of supports in a liquid
crystal layer in an implementation example 2 of the liquid crystal
display element according to the preferred embodiment.
[0038] FIG. 7 shows the arrangement pattern of supports in a liquid
crystal layer in an implementation example 3 of the liquid crystal
display element according to the preferred embodiment.
[0039] FIG. 8 shows the arrangement pattern of supports in a liquid
crystal layer in an implementation example 4 of the liquid crystal
display element according to the preferred embodiment.
[0040] FIG. 9 shows the arrangement pattern of supports in a liquid
crystal layer in an implementation example 5 of the liquid crystal
display element according to the preferred embodiment.
[0041] FIG. 10 shows the arrangement pattern of supports in a
liquid crystal layer in an implementation example 6 of the liquid
crystal display element according to the preferred embodiment.
[0042] FIG. 11 shows the arrangement pattern of supports in a
liquid crystal layer in an implementation example 7 of the liquid
crystal display element according to the preferred embodiment.
[0043] FIG. 12 shows the arrangement pattern of supports in a
liquid crystal layer in an implementation example 8 of the liquid
crystal display element according to the preferred embodiment.
[0044] FIG. 13 shows the arrangement pattern of supports in a
liquid crystal layer in an implementation example 9 of the liquid
crystal display element according to the preferred embodiment.
[0045] FIG. 14 is an exploded view showing the entire configuration
of the liquid crystal display element according to the preferred
embodiment, which has the liquid crystal layer of an implementation
example 10.
[0046] FIG. 15 shows the pattern of wall surface structures in the
liquid crystal layer of the implementation example 10.
[0047] FIG. 16 is a cross-sectional view of a color liquid crystal
display element using cholesteric liquid crystal of selective
reflection type, which is an implementation example 11 of the
present invention.
[0048] FIG. 17A to 17C respectively show the arrangement patterns
of supports of a B (blue) display panel, a G (green) display panel,
and an R (red) display panel in the color liquid crystal display
element of the implementation example 11.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0049] Preferred embodiments according to the present invention are
described below with reference to the drawings.
[0050] FIGS. 2 and 3 show the cell structure of a liquid crystal
display element of matrix system using cholesteric liquid crystal,
which is one preferred embodiment of the present invention. FIG. 2
is an exploded view showing the entire configuration of the liquid
crystal display element according to the preferred embodiment, FIG.
3 is a schematic showing the arrangement configuration of supports
in the liquid crystal display element according to the preferred
embodiment, and FIG. 4 shows the arrangement configuration of
openings provided between supports in the liquid crystal display
element according to the preferred embodiment.
[0051] Initially, the entire configuration of the liquid crystal
display element of matrix system (hereinafter referred to simply as
a liquid crystal display element) according to this preferred
embodiment is described with reference to FIG. 2. In FIG. 2, the
same constituent elements as those of FIG. 1 are denoted with the
same reference numerals.
[0052] The most distinguished characteristic, which is different
from a conventional liquid crystal display element of matrix
system, of the cell structure of the liquid crystal display element
10 of matrix system according to this preferred embodiment shown in
FIG. 2 is the shape of a support 15 (adhesive support) 15 in a
liquid crystal layer.
[0053] The support 15 provided in the liquid crystal layer of the
liquid crystal display element 10 is a wall surface structure
(first wall surface structure) the cross-section of which is
cross-shaped, and manufactured, for example, with photolithography.
This support is of a material having a property adhering to an
opposed second substrate 2. Supports 15 are provided at the four
sides (corners?) of each pixel. Additionally, as a spacer of the
liquid crystal layer, this wall surface structure and a
conventional spherical spacer or a square support spacer may be
used together.
[0054] FIG. 3 is a schematic showing the arrangement form
(arrangement pattern) of the supports 15.
[0055] A portion where a column electrode 21 and a row electrode
(scanning electrode) 23 intersect is a pixel 25. At the four sides
of this pixel 25, the supports 15 are provided. At the perimeters
of all of the supports 15, a wall surface structure (second wall
surface structure) 17 that stipulates the outer frame of a region
(liquid crystal pouring region), into which liquid crystal is
poured, is arranged. The entire shape of the wall surface structure
17 is nearly rectangular, and an inlet 14 of the liquid crystal is
provided at the center of one side 17a. Namely, this inlet 14 is a
portion of the wall surface structure 17. This wall surface
structure 17 is a member having adhesiveness. The supports 15 and
the wall surface structure 17 may be a same member. In this case,
they can be simultaneously formed in a photolithography
process.
[0056] Outside the wall surface structure 17, a seal member 13 is
arranged apart by a predetermined distance. This seal member 13 is
arranged at the perimeter of a liquid crystal display element cell.
This preferred embodiment is configured so that the wall surface
structure 17 having adhesiveness can be used along with the seal
member 13 when the substrates 1 and 2 are bonded.
[0057] As described above, the cholesteric liquid crystal of
selective reflection type stays lit up in a gap between pixels, in
which no electrode exists. Therefore, a black matrix must be
provided. Accordingly, the black matrix 6 is provided on the back
of the second substrate 2 (see FIG. 2). As shown in FIG. 3, the
black matrix 6 is provided in a position overlapping the supports
15 in a vertical direction (direction vertical to the display
surface).
[0058] As shown in FIG. 4, contiguous pixels 25 are linked via an
opening 27 provided between the supports 15. This opening 27 is
provided to pour the liquid crystal into all of pixels 25 in the
liquid crystal layer. The liquid crystal is poured, for example,
with a vacuum infusion method, etc.
[0059] In the meantime, in the cell structure of the liquid crystal
display element 10 according to this preferred embodiment, the
support 15 is cross-shaped. Therefore, the opening 27 that links
pixels 25 can be made infinitesimal. The support 15 can be used as
a replacement for the black matrix when the opening 27 is made
infinitesimal as described above, whereby the black matrix 6 can be
also omitted.
[0060] In the liquid crystal display element 10 according to this
preferred embodiment shown in FIGS. 2 to 4, the perimeter of a
pixel is enclosed by supports 51, which are cross-shaped wall
surface structures, except for infinitesimal gaps (openings 27) at
the centers of four sides. Therefore, the flow of the liquid
crystal poured into the pixel is restricted. Therefore, even if
pressing force is applied to the display surface or the element is
bent, a display of the pixel can be prevented from varying.
[0061] Actually, the liquid crystal display element 10 according to
this preferred embodiment was created as a cholesteric liquid
crystal display element the pixel pitch of which is 0.24 mm, the
opening 27 of which is 0.03 mm, the display size of which is 3.8
inches, the film substrate of which has a thickness of 0.125 mm,
and the liquid crystal layer of which has a thickness of 4.0 .mu.m,
and a practical test was conducted for this element. As a result,
it was verified that the display of the cholesteric liquid crystal
display element does not vary even if it is bent with a curvature
radius of 60 mm. For the conventional cholesteric liquid crystal
display element shown in FIG. 1, its display varied only by holding
the element by hand.
[0062] As described above, with the liquid crystal display element
10 according to this preferred embodiment, a liquid crystal display
element of selective reflection type having flexibility (which is
applicable to electronic paper) can be implemented.
[0063] Additionally, the liquid crystal display element 10
according to this preferred embodiment has the structure where the
wall surface structure 17 is arranged along with the seal member on
the inner side of the seal member 13 as shown in FIG. 2. Therefore,
in the liquid crystal display element 10 according to this
preferred embodiment, the liquid crystal does not leak outside the
wall surface structure 17, and the seal member 13 and the liquid
crystal do not contact unlike a conventional liquid crystal display
element. For the conventional liquid crystal display element, an
expensive material must be used for a seal member in order to
prevent the liquid crystal from contacting the seal member and
being contaminated by impurities. Besides, it is difficult to
select a material having high adhesiveness as the seal member.
[0064] For the liquid crystal display element 10 according to this
preferred embodiment, its wall surface structure 17 is of a
material having adhesiveness. Therefore, the liquid crystal display
element 10 can be also configured by omitting the seal member 13.
Even when the liquid crystal display element 10 is configured by
using the seal member, there is no need to restrict the seal member
13 due to the above described reason. Accordingly, a low-cost
liquid crystal display element can be implemented with the liquid
crystal display element 10 according to this preferred
embodiment.
Implementation Example 1
[0065] FIG. 5 shows the arrangement pattern (a support arrangement
pattern) of supports 15 in the above described liquid crystal
display element 10. In the liquid crystal display element 10, a
pixel 25 is linked to all of its contiguous pixels via openings 27.
Although the openings 27 are required to pour the liquid crystal
into each pixel 25, they are not required to be provided between
contiguous pixels 25 in all cases (there is no need to link a pixel
25 to all of its four contiguous pixels via openings 27).
Implementation Example 2
[0066] FIG. 6 exemplifies another configuration of the support
arrangement pattern in the liquid crystal display element 10. In
the example shown in FIG. 6, a pixel 25 is linked to its three
contiguous pixels via openings 27. Accordingly, for example, pixels
25a and 25b are not linked via an opening 27. A support structure
shown in FIG. 6 is formed by patterning contiguous supports 15,
which are contiguous right and left, to be alternately linked in
the liquid crystal display element of the implementation example 1.
At this time, supports 15 to be linked are shifted right or left by
1 in odd- and even-numbered rows.
Implementation Example 3
[0067] FIG. 7 exemplifies a further configuration of the support
arrangement pattern in the liquid crystal display element 10.
[0068] In the example shown in FIG. 7, a pixel 25 is linked to its
two contiguous pixels via openings 27. A support structure shown in
FIG. 7 is formed by patterning supports, which are contiguous
upward and downward, to be alternately linked in the liquid crystal
display element of the implementation example 1. At this time,
supports 15 to be linked are shifted upward or downward by 1 in
odd- and even-numbered columns.
[0069] In a fundamental structure of the liquid crystal display
element in this implementation example, the fluidity of liquid
crystal poured into a pixel 25 is restricted stronger as the number
of openings 27 becomes smaller. Therefore, the endurance of a
display variance against the bending of the element or pressing
force applied to the display surface becomes high. Additionally, as
a gap width of an opening 27 is smaller, the above described
endurance of the display variance is improved. Note that, however,
the amount of time required in the liquid crystal pouring process
increases as the gap of an opening 27 is smaller. Furthermore, it
is desirable to heat the liquid crystal in the liquid crystal
pouring process because the viscosity of the liquid crystal becomes
low at a high temperature. Also pressurization is effective at
shortening the amount of time.
Implementation Example 4
[0070] FIG. 8 exemplifies a still further configuration of the
support arrangement pattern in the liquid crystal display element
according to this preferred embodiment.
[0071] There are four types of supports shown in this figure. One
type is a nearly L-shaped support 35-1, the three other types have
shapes implemented by rotating the support 35-1 clockwise by 90,
180, and 270 degrees respectively. The support 35-2 is a support
implemented by rotating the support 35-1 by 90 degrees, the support
35-3 is a support implemented by rotating the support 35-1 by 180
degrees, and the support 35-4 is a support implemented by rotating
the support 35-1 by 270 degrees.
[0072] In this implementation example, these four types of supports
35-1 to 35-4 are arranged at four corners of a pixel 25. Namely,
the supports 35-1, 35-2, 35-3, and 35-4 are respectively arranged
at an upper left corner, an upper right corner, a lower right
corner, and a lower left corner.
[0073] The perimeter of a pixel 25 is configured by being enclosed
with these four types of supports 35 (35-1 to 35-4). Therefore, an
opening 37 in this implementation example is arranged in a position
obtained by moving the opening 27 of the implementation example 1
upward, downward, right, or left.
[0074] In the pattern configuration of the supports 15 in the
implementation example 1, the openings 27 are aligned in a linear
manner vertically or horizontally. Therefore, the liquid crystal
within a pixel 25 is easy to flow in this linear direction.
Actually, as a result of prototyping the liquid crystal display
element 10 of the implementation example 1 and conducting an
experiment, a display was proved to vary from a portion where the
openings 27 are aligned in a linear manner.
[0075] Therefore, a display variance, which is problematic in the
liquid crystal display element 10 of the implementation example 1,
can be prevented by patterning the supports 37 not to align the
openings 37 in a linear manner as shown in FIG. 8.
Implementation Example 5
[0076] FIG. 9 shows a still further example of the support
arrangement pattern in the liquid crystal display element according
to this preferred embodiment.
[0077] In the implementation example 5, contiguous supports 35 of
the implementation example 4 are linked with a method similar to
that of the implementation example 2. As a result, a pixel 25a is
linked to its right and left pixels 25c and 25d, and a downward
pixel 25e via openings 37, but it is not linked to its upward pixel
25b.
[0078] As described above, each pixel 25 is linked to three pixels
among four pixels, which are contiguous upward, downward, right,
and left, via openings 37 in the implementation example 5.
Implementation Example 6
[0079] FIG. 10 shows a still further example of the support
arrangement pattern in the liquid crystal display element according
to this preferred embodiment.
[0080] In the implementation example 6, contiguous supports 35 of
the implementation example 4 are linked with a method similar to
that of the implementation example 3. As a result, a pixel 25a is
linked to its left pixel 25c and downward pixel 25e via openings
37, but it is not linked to its upward pixel 25b and right pixel
25d.
[0081] As described above, each pixel 25 is linked to two pixels
among four pixels, which are contiguous upward, downward, right,
and left, via openings 37 in the implementation example 6.
[0082] In the liquid crystal display elements of the implementation
examples 5 and 6, the flow of the liquid crystal within a pixel 25
can be suppressed more effectively than that in the liquid crystal
display element of the implementation example 4.
[0083] For the liquid crystal layers of the above described
implementation examples 4 to 6, a portion (such as a slim portion)
of the pattern is sometimes lost in a photolithography process if a
support is infinitesimal, and the deterioration of process yield
becomes a concern. For example, if the width and the length of a
slim portion are approximately 10 .mu.m and 150 .mu.m respectively
in a support, there is a high probability that the support formed
in the photolithography process is easy to topple over and peel
off.
[0084] Accordingly, as a result of transforming the support to a
shape shown in FIG. 11, a loss caused by peel-off can be prevented
at the time of development in the photolithography process.
Implementation Example 7
[0085] FIG. 11 shows a still further example of the support
arrangement pattern in the liquid crystal display element according
to this preferred embodiment.
[0086] A liquid crystal layer of the implementation example 7 has a
pattern configuration where two types of supports 45a and 45b are
alternately arranged. The support 45b has a shape obtained by
rotating the support 45a clockwise by 180 degrees with its center
as an axis.
[0087] In the liquid crystal layer of the implementation example 7,
openings 47 of contiguous pixels 25 are not aligned in a linear
manner, whereby the fluidity of the liquid crystal within a pixel
25 can be suppressed. Additionally, since each support 45 (45a,
45b) has a highly symmetrical shape (the shape symmetrical with
respect to a point), it is proved that the support is difficult to
peel off in the photolithography process.
Implementation Example 8
[0088] FIG. 12 shows a still further example of the support
arrangement pattern in the liquid crystal display element according
to this preferred embodiment.
[0089] In a liquid crystal layer of the implementation example 8,
the two types of supports 45a and 45b in the liquid crystal layer
of the implementation example 7 are linked by a rule similar to
that of the liquid crystal layer of the implementation example 5.
Namely, the liquid crystal layer of the implementation example 8
has a configuration where horizontally contiguous two supports (the
supports 45a and 45b) in the liquid crystal layer of the
implementation example 7 are linked and integrated.
[0090] The linkage and the integration of these two contiguous
supports 45 (the supports 45a and 45b) are shifted by 1 in odd- and
even-numbered rows. As a result, all of odd-numbered lines have the
same arrangement pattern (a first arrangement pattern) of supports
451. In the meantime, all of even-numbered lines have the same
pattern (a second arrangement pattern) of supports 451.
[0091] In the liquid crystal layer of the implementation example 8,
each pixel has three openings 47, and is linked to three contiguous
pixels, which exist right, left, and upward or downward, via the
openings 47. However, the arrangement positions of the openings 47
in odd- and even-numbered rows differ. Therefore, the openings 47
of the pixels 25 are not aligned in a linear manner. Accordingly,
the fluidity of liquid crystal within each pixel 25 is suppressed
more than that in the implementation example 7.
Implementation Example 9
[0092] FIG. 13 shows a still further example of the support
arrangement pattern in the liquid crystal display element according
to this preferred embodiment.
[0093] In a liquid crystal layer of the implementation example 9,
the two types of supports 45a and 45b in the liquid crystal layer
of the implementation example 7 are linked with a rule similar to
that of the liquid crystal layer of the implementation example 6.
The liquid crystal layer of the implementation example 9 is
configured by linking and integrating the two types of supports
(the supports 45a and 45b) in the liquid crystal layer of the
implementation example 7 in both of vertical and horizontal
directions. Specifically, every other opening 47t arranged in the
vertical direction is linked, and every other opening 47y arranged
in the horizontal direction is linked.
[0094] As a result of linking the openings 47t and 47y as described
above, a pixel 25 of the liquid crystal layer of the implementation
example 9 has two openings 47 (the openings 47t and 47y). The pixel
25 in the liquid crystal layer of the implementation example 9 is
linked to two pixels such as its left or right contiguous pixel,
and its upward or downward contiguous pixel via the openings (the
openings 47t and 47y). However, these openings 47 are not aligned
in a linear manner. Accordingly, the fluidity of the liquid crystal
in a pixel of the liquid crystal layer of the implementation
example 9 is suppressed more than that in a pixel of the liquid
crystal layer of the implementation example 7. Additionally, the
number of openings in a pixel of the implementation example 9 is
smaller than that in a pixel of the implementation example 8.
Therefore, the fluidity of the poured liquid crystal in a pixel of
the implementation example 9 is lower than that in a pixel of the
implementation example 8.
Implementation Example 10
[0095] FIG. 14 is an exploded view showing the entire structure of
the liquid crystal display element according to this preferred
embodiment, which has a liquid crystal layer of another
configuration.
[0096] In the liquid crystal display element 50 shown in FIG. 14,
constituent elements having the same structures as those of the
constituent elements comprised by the liquid crystal display
element 10 of FIG. 2 are denoted with the same reference
numerals.
[0097] The liquid crystal display element 50 is characterized in
that pixels 55 are not linked with openings in a liquid crystal
layer. Namely, as shown in FIG. 15, in the liquid crystal display
element 50, the four sides of a pixel 55 of the liquid crystal
layer 55 are sealed by an adhesive wall surface structure (a first
wall surface structure) 59. Namely, all of side faces at the
perimeter of each pixel 55 are covered with the wall surface
structure (the first wall surface structure) 59, and each pixel is
not linked to its contiguous pixels. Accordingly, the fluidity of
the liquid crystal within the pixel 55 is completely suppressed.
Additionally, a rectangular second wall surface structure 57 is
arranged at the perimeter of the first wall surface structure 59.
Also the second wall surface structure 57 has adhesiveness. The
first wall surface structure 59 and the second wall surface
structure 57 are a same member, and formed in the same process.
Additionally, a rectangular seal member 54 is arranged at the
perimeter of the second wall surface structure 57. A same member
can be used as the first and the second wall surface structures
(59, 57) and the seal member 54, and can be formed in the same
process.
[0098] In the manufacturing process of the liquid crystal display
element 50 of the implementation example 10, the liquid crystal is
poured into a pixel 55, for example, by being dripped into the
pixel 55. Upon completion of the pouring of the liquid crystal into
the pixel 55, a liquid crystal cell is manufactured by bonding the
substrates 1 and 2 with the use of the wall surface structures 57
and 59, and the seal member 54.
[0099] Also the implementation example 10 has a configuration where
the liquid crystal poured into a pixel does not contact the seal
member 54. This is because the liquid crystal is dripped into only
the first and the second wall surface structures 59 and 57, or the
first wall surface structure 59. Therefore, a low-cost material and
a material having high adhesiveness can be used for the seal member
54. Furthermore, since the first and the second wall surface
structures (59, 57) have adhesiveness, the seal member 54 can be
also omitted.
[0100] In the meantime, air bubbles can be possibly contained in
the liquid crystal at the time of the process for dripping the
liquid crystal (cholesteric liquid crystal) into the pixel, and for
bonding the two substrates thereafter. Accordingly, it is desirable
to drip the liquid crystal and to bond the substrates in a
vacuum.
[0101] The liquid crystal display element 50 of the implementation
example 10 can be manufactured also by adding a new process to the
process for manufacturing the liquid crystal display elements of
the implementation examples 1 to 9. For example, a process for
closing openings is executed after the liquid crystal is poured
into a pixel in the process for manufacturing the liquid crystal
display elements of the implementation examples 1 to 9. In this
case, for example, the size of an opening is reduced to a minimum,
and a wall surface structure is widened (expanded) by heating and
pressurizing the liquid crystal until the opening is closed, after
the liquid crystal is poured.
Implementation Example 11
[0102] FIGS. 16 and 17 show the principal portions of a color
liquid crystal display element, which is an implementation example
11 of the present invention. FIG. 16 is a cross-sectional view of
the color liquid crystal display element using the cholesteric
liquid crystal of selective reflection type.
[0103] As shown in this figure, the color liquid crystal display
element of the implementation example 11 is configured by
sequentially stacking an R (red) display panel (liquid crystal
panel) 610, a G (green) display panel (liquid crystal panel) 620,
and a B (blue) display panel (liquid crystal panel) 630, among
which the B display panel 630 is the uppermost layer.
[0104] The R display panel 610, the C display panel 620, and the B
display panel 630 respectively have the support arrangement
patterns shown in FIGS. 17A to C. Namely, the R display panel 610,
the G display panel 620, and the B display panel 630 have the
support arrangement pattern of the implementation example 1 (see
FIG. 5), the support arrangement pattern of the implementation
example 4 (see FIG. 8), and the support arrangement pattern of the
implementation example 4 respectively. Note that the support
pattern of the B display panel 630 is a structure implemented by
transforming the support pattern of the implementation example 4.
As a result, between the G display panel 620 and the B display
panel 630, openings between supports are configured not to be
arranged in a linear manner in a vertical direction (direction
vertical to the display surface).
[0105] The reason of adopting such a structure is that the openings
of each of the RGB panels, which are contiguous in the vertical
direction, are arranged in a linear manner if all of the support
arrangement patterns of the three panels 610 to 630 are implemented
as the configuration of the implementation example 1. Since the
liquid crystal existing at an opening between supports stays lit
up, all of the three RGB colors are viewed as being lit up to user
eyes, and the contrast of the display deteriorates. For this
reason, the need for providing a black matrix in the positions of
openings arises. This implementation example is devised so that the
openings of the G display panel 620 and those of the R display
panel 630 are not aligned in a linear manner in the vertical
direction as described above, thereby eliminating the need for a
black matrix.
[0106] Namely, as shown in FIG. 16, this display element is
configured so that an opening 617 between pixels 25R of the R
display panel 610, an opening 627 between pixels 25G of the G panel
620, and an opening 637 between pixels 25B of the B panel 630 are
not arranged in a linear manner in the vertical direction.
Accordingly, if a support is not completely transparent, noise
light, which is caused by the lit-up state at the openings (617,
627) of the lower layer panels (the R display panel 610 and the G
display panel 620 in this implementation example), is reduced. If
the transparency of a support is low, only the openings 637 of the
uppermost layer panel (the B display panel 630 in this
implementation example) may be configured not to be arranged in
positions in a direction (immediately above) vertical to the
openings (617, 627) of the lower layer panels (610, 620).
[0107] If the display element is configured without providing the
black matrix, the openings of the pixels on the uppermost layer
panel are lit up. In this implementation example, the uppermost
layer panel is implemented as the B (blue) display panel 630 which
makes the sensitivity characteristic of human eyes to an optical
wavelength low. Accordingly, with the color liquid crystal display
element of this implementation example, deterioration of the
display characteristic of the color liquid crystal display element
can be reduced even if a black matrix is omitted, and its display
performance becomes a level which is not practically problematic.
Therefore, a low-cost color liquid crystal display element from
which a black matrix is omitted can be implemented with the color
liquid crystal display element of this implementation example.
[0108] In the above described implementation examples, the amount
of time required to pour the liquid crystal is expected to become
longer as the number of openings decreases. However, if the
viscosity of the liquid crystal is reduced by raising the
temperature of the liquid crystal when being poured, the liquid
crystal display element can be manufactured for an amount of time,
which is not problematic from the viewpoint of a process.
[0109] As described above, according to the preferred embodiment of
the present invention, in the cholesteric liquid crystal display
element having bistability, a variance in a display state, which is
a problem and caused by applying pressing force to a display
surface, can be prevented. Additionally, resistance to pressing
force or a strength against bending are improved, whereby
flexibility can be imparted to the cholesteric liquid crystal
display element. Additionally, a black matrix becomes unnecessary,
whereby a low-cost cholesteric liquid crystal display element can
be implemented. Furthermore, since liquid crystal does not contact
a seal member, a low-cost material can be used for the seal member.
Still further, the seal member can be also omitted by enhancing the
adhesiveness of a wall surface structure existing at the perimeter
of supports. In this way, a lower-cost cholesteric liquid crystal
display element can be provided. Besides, the second wall surface
structure is a nearly rectangular enclosing structure. However, if
the seal member is used together, the second wall surface structure
may not be an enclosing structure. Still further, in that case, the
shape of the second wall surface structure may be made identical to
that of the first structure arranged for each pixel. It is
desirable that the first wall surface structure for a pixel in an
end column and the second wall surface structure at the perimeter
of the pixel contact although this is not shown. With the second
wall surface structure, the fluidity of the liquid crystal can be
reduced even in a pixel in the end column.
[0110] In the meantime, all of the supports in the implementation
examples have shapes based on a cross, which can maximize an
aperture ratio. However, the shapes of the supports of the present
invention are not limited to those referred to in the
implementation examples. Various shapes such as a shape obtained by
transforming a cross, etc. can be considered. Additionally, the
number of openings for a contiguous pixel may not be necessarily
one. A plurality of small openings may be provided between a pixel
and its contiguous pixel. Furthermore, a cylinder or a square
support may be arranged together within a pixel. With such a
configuration, liquid crystal can be prevented from flowing, and
also a synergistic effect of being able to reducing the
transformation of a pixel can be expected.
[0111] Additionally, a wall surface structure and a conventional
spacer may be used together.
[0112] Furthermore, the above described implementation examples are
the liquid crystal display elements of a simple matrix system.
However, the present invention is easily applicable also to a
liquid crystal display element of an active matrix system. Besides,
the shape of a pixel in the implementation examples is rectangular.
However, the shape of a pixel of the present invention is not
limited to a rectangle, and may take another shape.
[0113] Still further, the present invention is applicable not only
to the cholesteric liquid crystal display element but also to a
liquid crystal display element using another liquid crystal having
a memory property of display.
[0114] The present invention is superior in flexibility,
shock-resistance, and resistance to pressing force against a
display surface. Therefore, the present invention is preferable as
a display element of electronic paper.
[0115] The present invention is preferable also for an electronic
book, an electronic newspaper, an electronic poster, a portable
terminal such as a PDA (Personal Data Assistant), etc., and a
display element of portable appliances such as a wrist watch, etc.,
for which flexibility is required, in addition to the display
element of electronic paper. Furthermore, the present invention is
applicable also to a display element of a display unit of a
computer of paper type, which is expected to be realized in the
future, and to display devices in various fields such as a display
decorated in a store, etc.
* * * * *