U.S. patent application number 16/729952 was filed with the patent office on 2020-04-30 for liquid crystal panel and method of manufacturing thereof.
The applicant listed for this patent is SHARP KABUSHIKI KAISHA. Invention is credited to FUMIKAZU SHIMOSHIKIRYOH, SHINICHI TERASHITA, KOUICHI WATANABE.
Application Number | 20200133079 16/729952 |
Document ID | / |
Family ID | 68056077 |
Filed Date | 2020-04-30 |
![](/patent/app/20200133079/US20200133079A1-20200430-D00000.png)
![](/patent/app/20200133079/US20200133079A1-20200430-D00001.png)
![](/patent/app/20200133079/US20200133079A1-20200430-D00002.png)
![](/patent/app/20200133079/US20200133079A1-20200430-D00003.png)
![](/patent/app/20200133079/US20200133079A1-20200430-D00004.png)
![](/patent/app/20200133079/US20200133079A1-20200430-D00005.png)
![](/patent/app/20200133079/US20200133079A1-20200430-D00006.png)
![](/patent/app/20200133079/US20200133079A1-20200430-D00007.png)
![](/patent/app/20200133079/US20200133079A1-20200430-D00008.png)
![](/patent/app/20200133079/US20200133079A1-20200430-D00009.png)
![](/patent/app/20200133079/US20200133079A1-20200430-D00010.png)
View All Diagrams
United States Patent
Application |
20200133079 |
Kind Code |
A1 |
SHIMOSHIKIRYOH; FUMIKAZU ;
et al. |
April 30, 2020 |
LIQUID CRYSTAL PANEL AND METHOD OF MANUFACTURING THEREOF
Abstract
A liquid crystal panel includes: a first substrate including
multiple pixel electrodes; a liquid crystal layer; and a second
substrate. The domains in the display unit region located in an nth
row are arranged in an order of a first domain, a second domain, a
third domain, and a fourth domain. Each of the pixel electrodes is
provided with multiple fine slits parallel to the alignment vectors
of the respective domains. Each of the pixel electrodes includes a
region where the fine slits do not exist, at both ends of the pixel
electrode parallel to the row direction and at one or both of ends
of the pixel electrode parallel to the column direction. A portion
having a largest width of the region where the fine slits do not
exist is included in one or both of the ends of the pixel electrode
parallel to the row direction.
Inventors: |
SHIMOSHIKIRYOH; FUMIKAZU;
(Sakai City, JP) ; TERASHITA; SHINICHI; (Sakai
City, JP) ; WATANABE; KOUICHI; (Sakai City,
JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SHARP KABUSHIKI KAISHA |
Sakai City |
|
JP |
|
|
Family ID: |
68056077 |
Appl. No.: |
16/729952 |
Filed: |
December 30, 2019 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
16366911 |
Mar 27, 2019 |
10551681 |
|
|
16729952 |
|
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G02F 2201/121 20130101;
G02F 1/133707 20130101; G02F 2001/133757 20130101; G02F 1/134309
20130101; G02F 2201/123 20130101; G02F 1/136286 20130101; G02F
1/133788 20130101; G02F 1/134336 20130101; G02F 1/133753
20130101 |
International
Class: |
G02F 1/1337 20060101
G02F001/1337; G02F 1/1343 20060101 G02F001/1343; G02F 1/1362
20060101 G02F001/1362 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 28, 2018 |
JP |
2018-062303 |
Claims
1. A liquid crystal panel comprising, in the following order: a
first substrate including multiple pixel electrodes arranged into a
matrix form, multiple gate lines, and a first alignment film; a
liquid crystal layer containing liquid crystal molecules; and a
second substrate including a common electrode and a second
alignment film, wherein an alignment vector is defined as being
from a first substrate side long-axis end of each of the liquid
crystal molecules, a start point, to a second substrate side
long-axis end of the liquid crystal molecule, an end point, and the
first alignment film and the second alignment film having been
subjected to an alignment treatment each include multiple domains
with different alignment vectors in a column direction in each
display unit region superimposed on one of the pixel electrodes, in
at least 30 pixels consecutive in a row direction, arrays of the
domains are identical, the gate lines extend through a region
between rows of the display unit regions, the domains in the
display unit region located in an nth row, where n is any integer
of 1 or more, are arranged in an order of a first domain in which a
direction of the alignment vector is a first direction, a second
domain in which a direction of the alignment vector is a second
direction, a third domain in which a direction of the alignment
vector is a third direction, and a fourth domain in which a
direction of the alignment vector is a fourth direction, the
domains in the display unit region located in an (n+2)th row are
arranged in a same order as the domains in the display unit region
located in the nth row.
2. The liquid crystal panel according claim 1, wherein the domains
in the display unit region located in the(n+2)th row are arranged
in different order from the domains in the display unit region
located in a (n+1)th row.
3. The liquid crystal panel according claim 1, wherein the gate
lines includes at least one gate line arranged between the display
un region located in the nth row aid the display unit region
located in a (n+1)th row.
4. The liquid crystal panel according claim 1, wherein in a plan
view of the display unit region located in the nth row, the
alignment vector of the first domain and the alignment vector of
the second domain have a relationship in which the end points are
opposed to each other and the alignment vectors are orthogonal to
each other, the alignment vector of the second domain and the
alignment vector of the third domain have a relationship in which
the start points are opposed to each other and the alignment
vectors are parallel to each other, and the alignment vector of the
third domain and the alignment vector of the fourth domain have a
relationship in which the end points are opposed to each other and
the alignment vectors are orthogonal to each other.
5. The liquid crystal panel according to claim 1, wherein the
liquid crystal molecules are aligned substantially vertically to
the first substrate and the second substrate when no voltage is
applied to the liquid crystal layer, and the liquid crystal
molecules are obliquely aligned so as to be matched with the
alignment vectors of the domains when voltage is applied to the
liquid crystal layer.
6. The liquid crystal panel according to claim 1, wherein in the
domains, an inter-substrate twist angle of the liquid crystal
molecules is less than or equal to 45.degree..
7. The liquid crystal panel according to claim 1, wherein each of
the first domain, the second domain, the third domain, and the
fourth domain has a substantially rectangular shape.
8. The liquid crystal panel according to claim 1, wherein the
domains in the display unit region located in an(n+1)th row
adjacent to the nth row with at least one of the gate lines
interposed therebetween satisfy a relationship in which the first
domain and the fourth domain are located between the second domain
and the third domain.
9. The liquid crystal panel according to claim 8, wherein the
domains in the display unit region located in the(n+1)th row are
arranged in an order of the third domain, the fourth domain, the
first domain, and the second domain.
10. The liquid crystal panel according to claim 1, wherein at least
one of the first alignment film or the second alignment film is a
photo alignment film.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application is a continuation application of
U.S. patent application Ser. No. 16/366,911, filed on Mar. 27,
2019, which designated the U.S. and claims priority to Japanese
Patent Application No. 2018-062303 filed in Japan on Mar. 28, 2018.
The entire disclosure of such parent application is incorporated
herein by reference.
BACKGROUND OF THE INVENTION
Field of the Invention
[0002] The present invention relates to a liquid crystal panel and
a method of manufacturing thereof. More particularly, the present
invention relates to a liquid crystal panel having a configuration
in which one pixel is divided into multiple alignment regions
(domains) and a method suitable for manufacturing of the liquid
crystal panel.
Description of Related Art
[0003] A liquid crystal display device is a display device in which
a liquid crystal composition is used to perform display. In a
typical display system for the liquid crystal display device, the
liquid crystal composition enclosed between a pair of substrates is
irradiated with light from a backlight, and voltage is applied to
the liquid crystal composition to change alignment of liquid
crystal molecules, thereby controlling an amount of light
transmitted through the liquid crystal panel. Because the liquid
crystal display device has the features such as a low profile,
light weight, and low power consumption, the liquid crystal display
device is used in electronic products such as a smartphone, a
tablet PC, and an automotive navigation system.
[0004] Conventionally, an alignment division technique has been
studied. In the alignment division technique, one pixel is divided
into multiple alignment regions (domains), and the liquid crystal
molecules are aligned at different azimuths in different alignment
regions, thereby improving a viewing angle characteristic. JP
2015-31961 A can be cited as an example of a citation list
disclosing the alignment division technique.
[0005] A liquid crystal display device disclosed in JP 2015-31961 A
includes: a display substrate that includes multiple pixel regions
and has a curved shape bent according to a first direction; a
counter substrate that is opposed and coupled to the display
substrate and has a curved shape together with the display
substrate; and a liquid crystal layer disposed between the display
substrate and the counter substrate. In the liquid crystal display
device, multiple domains are defined in each of the pixel regions,
at least two of the domains are different from each other in a
direction in which liquid crystal molecules of the liquid crystal
layer are aligned, and the domains are arrayed in a second
direction crossing the first direction.
BRIEF SUMMARY OF THE INVENTION
[0006] Sometimes display unevenness having a viewing angle
characteristic is generated in the liquid crystal panel in which
the alignment division technique is used. Because the display
unevenness has the viewing angle characteristic, the display
unevenness can hardly be suppressed by a publicly known
conventional unevenness correction technique. For this reason,
there is a demand for a method of suppressing the display
unevenness having the viewing angle characteristic.
[0007] The present invention has been made in view of such a
current state of the art and aims to provide a liquid crystal panel
in which the display unevenness having viewing angle dependency is
suppressed and a method suitable for manufacturing of the liquid
crystal panel.
[0008] As a result of extensive studies on the cause of occurrence
of display unevenness having viewing angle dependency, the
inventors have found that in the case that a fine slit is provided
in a pixel electrode, an electric field from the gate line below
the pixel electrode influences the liquid crystal Layer to change
luminance of the liquid crystal panel. In the liquid crystal panel
in which one pixel is divided into alignment regions (domains), the
inventors have also found that display unevenness having viewing
angle dependency is generated because a degree of influence of the
electric field from the gate line varies between the domains.
Thereby, the inventors have arrived at the solution to the above
problem when a distance from to an end of a fine slit to an end of
the pixel electrode is lengthened in the domain close to the gate
line, completing the present invention.
[0009] According to one aspect of the present invention, there is
provided a liquid crystal panel including: a first substrate
including multiple pixel electrodes arranged into a matrix form,
multiple gate lines, and a first alignment film; a liquid crystal
layer containing liquid crystal molecules; and a second substrate
including a common electrode and a second alignment film, wherein
an alignment vector is defined as being from a first substrate side
long-axis end of each of the liquid crystal molecules, a start
point, to a second substrate side long-axis end of the liquid
crystal molecule, an end point, and the first alignment film and
the second alignment film having been subjected to an alignment
treatment each include multiple domains with different alignment
vectors in a column direction in each display unit region
superimposed on one of the pixel electrodes, in at least 30 pixels
consecutive in a row direction, arrays of the domains are
identical, the gate lines extend through a region between rows of
the display unit regions, the domains in the display unit region
located in an nth row, where n is any integer of 1 or more, are
arranged in an order of a first domain in which a direction of the
alignment vector is a first direction, a second domain in which a
direction of the alignment vector is a second direction, a third
domain in which a direction of the alignment vector is a third
direction, and a fourth domain in which a direction of the
alignment vector is a fourth direction, each of the pixel
electrodes is provided, in the first domain, the second domain, the
third domain, and the fourth domain, with multiple fine slits
parallel to the alignment vectors of the respective domains, each
of the pixel electrodes includes a region where the fine slits do
not exist, at both ends of the pixel electrode parallel to the row
direction and at one or both of ends of the pixel electrode
parallel to the column direction, and a portion having a largest
width of the region where the fine slits do not exist is included
in one or both of the ends of the pixel electrode parallel to the
row direction.
[0010] According to another aspect of the present invention, there
is provided a method of manufacturing the liquid crystal panel, the
method including forming the fine slits by photolithography, the
photolithography including irradiating a photosensitive resin
formed on a conductive film with light through a mask in which a
pattern corresponding to the fine slits is formed and multiple
lenses.
[0011] The present invention can provide the liquid crystal panel
in which the display unevenness having the viewing angle dependency
is suppressed and the method suitable for manufacturing of the
liquid crystal panel.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] FIG. 1 is a cross-sectional view schematically illustrating
an example of a liquid crystal display device according to an
embodiment;
[0013] FIG. 2 is a schematic plan view illustrating an arrangement
relation of an oblique azimuth of liquid crystal molecules in a
liquid crystal layer of the embodiment and a color filter of a
second substrate;
[0014] FIG. 3 is a view illustrating a relationship between the
oblique azimuth of the liquid crystal molecules and an alignment
vector;
[0015] FIG. 4 is a schematic plan view illustrating the oblique
azimuth of the liquid crystal molecules in the liquid crystal layer
of the embodiment while the oblique azimuth is superposed on an
electrode and line structure of a first substrate;
[0016] FIGS. 5A and 5B are views in which all domains included in
pixels if an nth row and pixels of an (n+1)th row are organized
based on an adjacent relationship with respect to a gate line G,
FIG. 5A illustrates a domain group that is not adjacent to the gate
line G, and FIG. 5B illustrates a domain group adjacent to the gate
line G;
[0017] FIG. 6 is a view illustrating a modification of a pixel
electrode in FIG. 5B;
[0018] FIG. 7 is a schematic plan view illustrating an arrangement
relation of the oblique azimuth of liquid crystal molecules in a
liquid crystal layer and the color filter of the second substrate
of the modification;
[0019] FIG. 8 is a view illustrating photolithography using a
multi-lens;
[0020] FIG. 9A is a schematic cross-sectional view illustrating an
arrangement relation of the lenses in the multi-lens, and FIG. 9B
is a conceptual view illustrating a pattern of luminance unevenness
generated by scanning exposure in which the multi-lens in FIG. 9A
is used when the pixel electrode including fine slits and the gate
line are formed;
[0021] FIG. 10 is a schematic diagram illustrating an example of a
photo alignment treatment device;
[0022] FIG. 11 is a view illustrating an example of a photo
alignment treatment step using the photo alignment treatment
device;
[0023] FIG. 12A is a view illustrating the photo alignment
treatment performed on a TFT substrate (first substrate), FIG. 12B
is a view illustrating the photo alignment treatment performed on a
CF substrate (second substrate), and FIG. 12C is a view
illustrating a state after bonding of the TFT substrate and the CF
substrate that are subject to the photo alignment treatment;
[0024] FIG. 13 is a waveform chart schematically illustrating an
example of a waveform of voltage applied to a general liquid
crystal panel;
[0025] FIGS. 14A and 14B are views each illustrating the case that
the liquid crystal panel of the embodiment is bent, FIG. 14A
illustrates the state in which the liquid crystal panel is not
bent, and FIG. 14B illustrates the state in which the liquid
crystal panel is bent;
[0026] FIGS. 15A and 15B are views each illustrating the state of a
dark line in a portion in which misalignment is not generated in
the liquid crystal panel of the embodiment, FIG. 15A is a plan view
of the pixel, and FIG. 15B is a cross-sectional view taken along
line A-A';
[0027] FIGS. 16A and 16B are views each illustrating the state of
the dark line in a portion in which the misalignment of a first
form is generated in the liquid crystal panel of the embodiment,
FIG. 16A is a plan view of the pixel, and FIG. 16B is a
cross-sectional view taken along line A-A';
[0028] FIGS. 17A and 17B are views each illustrating the state of
the dark line in a portion in which the misalignment of a second
form is generated in the liquid crystal panel of the embodiment,
FIG. 17A is a plan view of the pixel, and FIG. 17B is a
cross-sectional view taken along line A-A';
[0029] FIGS. 15A and 18B are views each illustrating the case that
a first conventional liquid crystal panel is bent, FIG. 18A
illustrates the state in which the first conventional liquid
crystal panel is not bent, and FIG. 18B illustrates the state in
which the first conventional liquid crystal panel is bent;
[0030] FIGS. 19A and 19B are views each illustrating the state of
the dark line in a portion in which the misalignment is not
generated in the first conventional liquid crystal panel, FIG. 19A
is a plan view of the pixel, and FIG. 19B is a cross-sectional view
taken along line A-A';
[0031] FIGS. 20A and 20B are views each illustrating the state of
the dark line in a portion in which the misalignment of the first
form is generated in the first conventional liquid crystal panel,
FIG. 20A is a plan view of the pixel, and FIG. 20B is a
cross-sectional view taken along line A-A';
[0032] FIGS. 21A and 21B are views each illustrating the state of
the dark line in a portion in which the misalignment of the second
form is generated in the first conventional liquid crystal panel,
FIG. 21A is a plan view of the pixel, and FIG. 21B is a
cross-sectional view taken along line A-A';
[0033] FIGS. 22A and 22B are views each illustrating the case that
a second conventional liquid crystal panel is bent, FIG. 22A
illustrates the state in which the second conventional liquid
crystal panel is not bent, and FIG. 22B illustrates the state in
which the second conventional liquid crystal panel is bent;
[0034] FIGS. 23A and 23B are views each illustrating the state of
the dark line in a portion in which the misalignment is not
generated in the second conventional liquid crystal panel, FIG. 23A
is a plan view of the pixel, and FIG. 23B is a cross-sectional view
taken along line A-A';
[0035] FIGS. 24A and 24B are views each illustrating the state of
the dark line in a portion in which the misalignment of the first
form is generated in the second conventional liquid crystal panel,
FIG. 24A is a plan view of the pixel, and FIG. 24B is a
cross-sectional view taken along line A-A';
[0036] FIGS. 25A and 25B are views each illustrating the state of
the dark line in a portion in which the misalignment of the second
form is generated in the second conventional liquid crystal panel,
FIG. 25A is a plan view of the pixel, and FIG. 25B is a
cross-sectional view taken along line A-A';
[0037] FIGS. 26A and 26B are views each illustrating the case that
a third conventional liquid crystal panel is bent, FIG. 26A
illustrates the state in which the third conventional liquid
crystal panel is not bent, and FIG. 26B illustrates the state in
which the third conventional liquid crystal panel is bent;
[0038] FIGS. 27A and 27B are views each illustrating the state of
the dark line in a portion in which the misalignment is not
generated in the third conventional liquid crystal panel, FIG. 27A
is a plan view of the pixel, and FIG. 27B is a cross-sectional view
taken along line A-A';
[0039] FIGS. 28A and 28B are views each illustrating the state of
the dark line in a portion in which the misalignment of the first
form is generated in the third conventional liquid crystal panel,
FIG. 28A is a plan view of the pixel, and FIG. 28B is a
cross-sectional view taken along line A-A'; and
[0040] FIGS. 29A and 29B are views each illustrating the state of
the dark line in a portion in which the misalignment of the second
form is generated in the third conventional liquid crystal panel,
FIG. 29A is a plan view of the pixel, and FIG. 29B is a
cross-sectional view taken along line A-A'.
DETAILED DESCRIPTION OF THE INVENTION
[0041] Hereinafter, an embodiment of the present invention will be
described. However, the following embodiment is not intended to
limit the scope of the present invention, and appropriate
modifications can be made within the spirit of the present
invention.
[0042] FIG. 1 is a cross-sectional view schematically illustrating
an example of a liquid crystal display device according to an
embodiment. As illustrated in FIG. 1, the liquid crystal display
device of the embodiment includes a liquid crystal panel 100 and a
backlight 110 disposed on a back side of the liquid crystal panel
100. The liquid crystal panel 100 includes a back-side polarizing
plate 20, a first substrate 30 including multiple pixel electrodes
35 and a first alignment film 71, a liquid crystal layer 40
containing liquid crystal molecules 41, a second substrate 50
including a second alignment film 72 and a counter electrode
(common electrode) 51, and a display-surface-side polarizing plate
60 in this order. The liquid crystal panel 100 includes a sealing
material 80 around the liquid crystal layer 40.
[0043] A method of displaying the liquid crystal display device of
the embodiment will be described. In the liquid crystal display
device of the embodiment, light is incident on the liquid crystal
panel 100 from the backlight 110, and an amount of light
transmitted through the liquid crystal panel 100 is controlled by
switching the alignment of the liquid crystal molecules 41 in the
liquid crystal layer 40. The alignment of the liquid crystal
molecules 41 is switched by applying voltage to the liquid crystal
layer 40 using the multiple pixel electrodes 35 and the counter
electrode 51. When the voltage applied to the liquid crystal layer
40 is less than a threshold (at time of applying no voltage), the
initial alignment of the liquid crystal molecules 41 is controlled
by the first alignment film 71 and the second alignment film
72.
[0044] At the time of applying no voltage, the liquid crystal
molecules 41 are aligned substantially vertically to the first
substrate 30 and the second substrate 50. As used herein, the term
"substantially vertically" means that the liquid crystal molecules
41 are aligned slightly oblique to the first substrate 30 and the
second substrate 50 by the alignment treatment performed on the
first alignment film 71 and the second alignment film 72. A
pre-tilt angle of the liquid crystal molecules 41 with respect to
the first substrate 30 and the second substrate 50 at the time of
applying no voltage is preferably greater than or equal to
85.degree. and less than 90.degree.. When the voltage is applied
between the pixel electrode 35 and the counter electrode 51, a
vertical electric field is generated in the liquid crystal layer
40, and the liquid crystal molecules 41 are further obliquely
aligned while an oblique azimuth is maintained from the time of
applying no voltage.
[0045] The oblique azimuth of the liquid crystal molecules 41 will
be described as appropriate using an alignment vector in which in a
plan view of the liquid crystal panel 100, a first substrate 30
side long-axis end of each liquid crystal molecule 41 is defined as
a start point (hereinafter, also referred to as "a tail of a liquid
crystal director") 41S while the second substrate 50 side long-axis
end of the liquid crystal molecule 41 is defined as an end point
(hereinafter also referred to as "a head of the liquid crystal
director") 41T. The alignment vector is in the same direction as
the oblique azimuth of the liquid crystal molecules 41 with respect
to the first alignment film 71 on the side of the first substrate
30 and is in an opposite direction to the oblique azimuth of the
liquid crystal molecules 41 with respect to the second alignment
film 72 on the side of the second substrate 50. As used herein, the
term "azimuth" means a direction in a view projected onto a
substrate surface without consideration of an inclination angle (a
polar angle, the pre-tilt angle) from a normal direction of the
substrate surface. The liquid crystal molecules 41 are aligned
substantially vertically (aligned slightly obliquely) at the time
of applying no voltage, and are largely obliquely aligned at the
time of applying the voltage while the oblique azimuth at the time
of applying no voltage is maintained, so that the start point 41S
and the end point 41T of the alignment vector may be checked while
the voltage is applied to the liquid crystal layer 40.
[0046] Preferably the first alignment film 71 and the second
alignment film 72 are each a photo alignment film in which a photo
alignment film material is deposited to exert a function of
aligning the liquid crystal molecules 41 in a specific direction by
performing a photo alignment treatment. The photo alignment film
material means a general material that generates a structural
change when irradiated with light (electromagnetic wave) such as
ultraviolet light and visible light, thereby exerting an ability of
controlling the alignment of the nearby liquid crystal molecules 41
(alignment controlling force) or changing the alignment controlling
force level and/or direction. For example, the photo alignment film
material includes a photoreactive site in which a reaction such as
dimerization (dimer formation), isomerization, photo Fries
rearrangement, and decomposition is generated by light irradiation.
Examples of the photoreactive sites (functional groups) that
dimerize and isomerize by the light irradiation include cinnamate,
cinnamoyl, 4-chalcone, coumarin, and stilbene. Azobenzene can be
cited as an example of the photoreactive site (functional group)
that isomerizes by the light irradiation. A phenol ester structure
can be cited as an example of the photoreactive site that undergoes
the photo Fries rearrangement by the light irradiation. Dianhydride
containing a cyclobutane ring such as
1,2,3,4-cyclobutanetetracarboxylic acid-1, 2: 3,4-dianhydride
(CBDA) can be cited as an example of the photoreactive site that is
decomposed by the light irradiation. Preferably the photo alignment
film material exhibits a vertical alignability that can be used in
a vertical alignment mode. Examples of the photo alignment film
materials include polyamide (polyamic acid), polyimide,
polysiloxane derivative, methyl methacrylate, and polyvinyl alcohol
that contain the photoreactive site.
[0047] FIG. 2 is a schematic plan view illustrating an arrangement
relation of the oblique azimuth of the liquid crystal molecules 41
in the liquid crystal layer 40 of the embodiment and a color filter
of the second substrate 50. As illustrated in FIG. 2, in the liquid
crystal panel 100 of the embodiment, multiple pixels 10 are
arranged into a matrix form of N rows and M columns (N and N are
integers of 1 or more). As used herein, the pixel 10 means a
display unit region superimposed on a single pixel electrode 35,
and an R pixel superimposed on a color filter of R (red), a G pixel
superimposed on a color filter of G (green), and a B pixel
superimposed on the color filter of B (blue) are provided in the
pixel 10. In FIG. 2, a portion surrounded by a one dot chain line
is one pixel. Stripe-shaped color filters extending in the column
direction are arranged on the second substrate 50 in order of R, G,
B in the row direction. That is, the arrangement order of the
pixels 10 in the row direction is repetition of the R pixel, the G
pixel, and the B pixel, and the pixels 10 having the identical
color are consecutively arranged in the column direction.
[0048] Four domains having different alignment vectors are provided
in each pixel 10. These domains can be formed by varying the
alignment treatment performed on the first alignment film 71 and
the second alignment film 72. When the voltage is applied to the
liquid crystal layer 40, the liquid crystal molecules 41 are
obliquely aligned so as to be matched with the alignment vector of
each domain.
[0049] In FIG. 2, in order to easily understand the oblique azimuth
of the liquid crystal molecules 41, the liquid crystal molecules 41
are represented by pins (cones), the bottom surface of the cone
represents the side of the second substrate 50 (observer side), and
a vertex of the cone represents the side of the first substrate 30.
FIG. 3 is a view illustrating a relationship between the oblique
azimuth of the liquid crystal molecules 41 and the alignment
vector.
[0050] The domains in the pixel located in the nth row (n is any
integer greater than or equal to 1) are arranged in the order of a
first domain 10a in which the direction of the alignment vector is
a first direction, a second domain 10b in which the direction of
the alignment vector is a second direction, a third domain 10c in
which the direction of the alignment vector is a third direction,
and a fourth domain 10d in which the direction of the alignment
vector is a fourth direction. The group of identical-color pixels
consecutive in the column direction may include the pixels 10 in
which the arrangement order of the four domains varies.
Specifically, the domains in the pixel (the (n+1)th row pixel)
located in the (n+1)th row adjacent to the nth row preferably
satisfy the relationship in which the first domain 10a and the
fourth domain 10d are located between the second domain 10b and the
third domain 10c. As illustrated in FIG. 2, more preferably the
domains in the (n+1)th row pixel are arranged in the order of the
third domain 10c, the fourth domain 10d, the first domain 10a, and
the second domain 10b. Two kinds of pixels having different
arrangement order of the four domains may be alternately and
repeatedly arranged in the group of identical-color pixels
consecutive in the column direction. In other words, pixels having
different domain arrangement order may be arranged in two row
periods. In this case, as illustrated in FIG. 2, the domains in the
pixel located in the (n+2)th row are arranged in the order of the
first domain 10a, the second domain 10b, the third domain 10c, and
the fourth domain 10d. At least one gate line G extends between the
nth row pixel and the (n+1)th row pixel.
[0051] From the viewpoint of obtaining a good viewing angle
characteristic, the alignment vectors of the first domain 10a, the
second domain 10b, the third domain 10c, and the fourth domain 10d
are a combination of four alignment vectors that face in directions
different from one another by 90.degree.. The alignment vector of
each domain can be decided by the direction of the liquid crystal
molecules 41 located in the center of the domain in a plan view and
located in the center of the liquid crystal layer in a
cross-sectional view.
[0052] From the viewpoint of suppressing a dark line generated
between the domains, in a plan view of the nth row pixel, the
alignment vectors of the first domain 10a, the second domain 10b,
the third domain 10c, and the fourth domain 10d preferably have the
following relationships (1) to (3).
[0053] (1) The alignment vectors of the first domain 10a and the
second domain 10b have a relationship, in which the end points are
opposed to each other and the alignment vectors are orthogonal to
each other (forming an angle of about 90.degree.) (hereinafter
referred to as "a domain boundary condition A").
[0054] (2) The alignment vectors of the second domain 10b and the
third domain 10c have a relationship, in which the start points are
opposed to each other and the alignment vectors are parallel to
each other (forming an angle of about 180.degree.) (hereinafter
referred to as "a domain boundary condition B").
[0055] (3) The alignment vectors of the third domain 10c and the
fourth domain 10d have the relationship (domain boundary condition
A), in which the end points are opposed to each other and the
alignment vectors are orthogonal to each other (forming the angle
of about 90.degree.).
[0056] As used herein, in the term "orthogonal (forming the angle
of about 90.degree.)", the alignment vectors may be substantially
orthogonal to each other within a range where the effect of the
present invention is obtained, specifically the term "orthogonal"
means that the alignment vectors form an angle of 75.degree. to
105.degree., preferably an angle of 80.degree. to 100.degree., more
preferably an angle of 85.degree. to 95.degree.. In the term
"parallel (forming an angle of about 180.degree.)", the alignment
vectors may be substantially parallel to each other within the
range where the effect of the present invention is obtained,
specifically the term "parallel" means that the alignment vectors
form an angle of -15.degree. to +15.degree. , preferably an angle
of -10.degree. to +10.degree., more preferably an angle of
-5.degree. to +5.degree..
[0057] The dark line is formed due to discontinuity of the
alignment of the liquid crystal molecules 41 at a boundary between
the domains having different alignment azimuths of the liquid
crystal molecules 41. In the region where the alignment of the
liquid crystal molecules 41 is discontinuous, because the liquid
crystal molecules 41 cannot be aligned in an intended direction,
the light can insufficiently be transmitted during display, and the
region is recognized as a dark portion. The dark portion formed in
a linear shape is called the dark line. When the dark line is
generated, transmittance (contrast ratio) of the pixel 10
decreases, so that light use efficiency of the liquid crystal panel
100 is degraded. In recent years, high definition of the pixel 10
has advanced and an area per pixel is reduced, but an area of the
dark line does not change even if the pixel 10 is reduced, so that
an area ratio occupied by the dark line in the pixel 10 increases,
and therefore prevention of the degradation of the light use
efficiency becomes more important. When the dark line is generated
at a different position in each pixel 10, uniformity of the display
is also degraded. On the other hand, the inventors have studied
that a generation situation of the dark line changes according to
the arrangement of the domains, and have found that the arrangement
of the domain boundary conditions A-B-A satisfying all of the
relationships (1) to (3) effectively suppresses the dark line.
[0058] In the first domain 10a, the second domain 10b, the third
domain 10c, and the fourth domain 10d, an inter-substrate twist
angle of the liquid crystal molecules 41 is preferably less than or
equal to 45.degree., more preferably about 0.degree.. That is, in
the first domain 10a, the second domain 10b, the third domain 10c,
and the fourth domain 10d, an angle formed between the oblique
azimuth of the liquid crystal molecules 41 with respect to the
first alignment film 71 on the side of the first substrate 30 and
the oblique azimuth of the liquid crystal molecules 41 with respect
to the second alignment film 72 on the side of the second substrate
50 is preferably less than or equal to 45.degree., more preferably
about 0.degree..
[0059] The planar shapes of the first domain 10a, the second domain
10b, the third domain 10c, and the fourth domain 10d are not
particularly limited. For example, the first domain 10a, the second
domain 10b, the third domain 10c, and the fourth domain 10d are
formed into a substantially rectangular shape. The rectangular
shape may be either a square or an oblong.
[0060] In the liquid crystal panel 100 of the embodiment, as
illustrated in FIG. 2, the arrangement order (domain array) of the
first domain 10a, the second domain 10b, the third domain 10c, and
the fourth domain 10d is identical in at least 30 pixels
consecutive in the row direction. The identical-domain-array pixels
arranged consecutively in the row direction preferably have at
least a ratio of one half to the total number of pixels in the row
direction of the display region, more preferably at least a ratio
of 90% to the total number of pixels in the row direction of the
display region. Further preferably the pixels arranged in the row
direction in the entire display region have the same domain array.
The pixels arranged in the row direction can have the same domain
array by performing the alignment treatment on the first alignment
film 71 and the second alignment film 72 using scanning exposure.
For example, the scanning exposure may be performed using a photo
alignment treatment device in FIG. 10.
[0061] The domain arrays of pixels arranged consecutively in the
row direction are made identical, which allows the suppression of
the generation of defects due to misalignment in a lateral
direction (row direction) of the liquid crystal panel 100.
Specifically, the generation of a display defect such as display
unevenness due to bending of the liquid crystal panel 100 can be
suppressed, and the effect that suppresses the generation of the
display defect appears notably in a higher-added-value,
large-sized, and high-definition liquid crystal panel.
Consequently, the liquid crystal panel 100 of the embodiment can
suitably be used for a higher-added-value, large-sized, and
high-definition liquid crystal display in which excellent display
quality is required. The liquid crystal panel 100 of the embodiment
can also be used for a high-designability, large-sized,
high-definition curved (non-planar) display. A method of thickening
a light shielding body is adopted as another method of improving
the display unevenness, but the transmittance decreases in this
method. In particular, because the high-definition liquid crystal
panel has the low transmittance, the further decrease in
transmittance causes a serious problem such as a loss of
marketability.
[0062] The liquid crystal panel 100 tends to become larger, lighter
(thinning of the glass substrate), and higher definition. The
liquid crystal panel 100 that becomes larger and lighter is easily
bent, and particularly easily bent in a long-side direction (row
direction). When the liquid crystal panel 100 is bent, the fitting
between the first substrate 30 and the second substrate 50 is
partially and irregularly misaligned. For a conventional liquid
crystal panel having a multi-domain structure, when the
misalignment is generated, a width and a shape of the dark line at
the domain boundary change, and the transmittance changes, so that
the display unevenness is generated. The display unevenness is a
belt-shaped unevenness extending from an upper end to a lower end
of the liquid crystal panel, and is sometimes generated at an
irregular position, which sometimes significantly degrades the
display quality of the entire liquid crystal panel. The display
unevenness tends to be easily generated in a relatively-expensive,
large-sized, and high-definition liquid crystal panel. On the other
hand, the liquid crystal panel 100 of the embodiment has the
multi-domain structure, but does not generate the changes of the
width and shape of the dark line due to the misalignment in the
lateral direction (row direction). Because the liquid crystal panel
100 of the embodiment has the identical domain array in the lateral
direction (row direction) so that the domain boundary and the dark
line do not exist in the lateral direction, this leads to an
essential measure against the display unevenness in the liquid
crystal panel 100 of the embodiment.
[0063] The generation situation of the display unevenness in the
case that the liquid crystal panel 100 is bent will be described
with reference to the drawings.
[0064] FIGS. 14A and 14B are views each illustrating the case that
the liquid crystal panel 100 of the embodiment is bent, FIG. 14A
illustrates the state in which the liquid crystal panel 100 is not
bent, and FIG. 14B illustrates the state in which the liquid
crystal panel 100 is bent. As illustrated in FIG. 14B, the display
defect is not generated in any one of a portion in which the
misalignment of a first form is generated, a portion in which the
misalignment is not generated, and a portion in which the
misalignment of a second form is generated. FIGS. 15A and 15B are
views each illustrating the state of a dark line in a portion in
which misalignment is not generated in the liquid crystal panel 100
of the embodiment, FIG. 15A is a plan view of the pixel, and FIG.
15B is a cross-sectional view taken along line A-A'. As illustrated
in FIGS. 15A and 15B, the dark line of a type A generated in a
region where the alignment changes continuously due to an influence
of the adjacent domain having different alignment is generated in a
domain boundary region. FIGS. 16A and 16B are views each
illustrating the state of the dark line in a portion in which the
misalignment of the first form is generated in the liquid crystal
panel 100 of the embodiment, FIG. 16A is a plan view of the pixel,
and FIG. 16B is a cross-sectional view taken along line A-A'. As
illustrated in FIGS. 16A and 16B, in the state in which the liquid
crystal panel 100 is bent, for example, the TFT substrate is
shifted onto the left side and the CF substrate is shifted onto the
right side, and the misalignment is generated. However, the
misalignment in the lateral direction does not influence the liquid
crystal alignment, and the dark line of the type A is generated
only in the domain boundary region. FIGS. 17A and 17B are views
each illustrating the state of the dark line in a portion in which
the misalignment of the second form is generated in the liquid
crystal panel 100 of the embodiment, FIG. 17A is a plan view of the
pixel, and FIG. 17B is a cross-sectional view taken along line
A-A'. As illustrated in FIGS. 17A and 17B, the misalignment in the
lateral direction does not influence the liquid crystal alignment,
and the dark line of the type A is generated only in the domain
boundary region.
[0065] FIGS. 18A and 18B are views each illustrating the case that
a first conventional liquid crystal panel is bent, FIG. 18A
illustrates the state in which the first conventional liquid
crystal panel is not bent, and FIG. 18B illustrates the state in
which the first conventional liquid crystal panel is bent. As
illustrated in FIG. 18B, the display defect is generated in the
portion in which the misalignment of the first form is generated
and the portion in which the misalignment of the second form is
generated. FIGS. 19A and 19B are views each illustrating the state
of the dark line in a portion in which the misalignment is not
generated in the first conventional liquid crystal panel, FIG. 19A
is a plan view of the pixel, and FIG. 19B is a cross-sectional view
taken along line A-A'. As illustrated in FIGS. 19A and 19B, the
dark line of the type A is generated only in the domain boundary
region. FIGS. 20A and 20B are views each illustrating the state of
the dark line in a portion in which the misalignment of the first
form is generated in the first conventional liquid crystal panel,
FIG. 20A is a plan view of the pixel, and FIG. 20B is a
cross-sectional view taken along line A-A'. As illustrated in FIGS.
20A and 20B, in a portion, in which the first conventional liquid
crystal panel is bent, and the TFT substrate is shifted onto the
left side while the CF substrate is shifted onto the right side,
thereby generating the misalignment of the first form, not only the
dark line of the type A is generated in the domain boundary region,
but also the dark line of a type B generated in the region where
the liquid crystal alignment becomes abnormal is generated by
mismatching of the alignment controlling regions on the TFT
substrate side and the CF substrate side due to the misalignment of
the upper and lower substrates. As a result, luminance is degraded
lower than the portion in which the misalignment is not generated.
FIGS. 21A and 21B are views each illustrating the state of the dark
line in a portion in which the misalignment of the second form is
generated in the first conventional liquid crystal panel, FIG. 21A
is a plan view of the pixel, and FIG. 21B is a cross-sectional view
taken along line A-A'. As illustrated in FIGS. 21A and 21B, in a
portion, in which the first conventional liquid crystal panel is
bent, and the TFT substrate is shifted onto the right side while
the CF substrate is shifted onto the left side, thereby generating
the misalignment of the second form, not only the dark line of the
type A is generated in the domain boundary region, but also the
dark line of the type B generated in the region where the liquid
crystal alignment becomes abnormal is generated by the mismatching
of the alignment controlling regions on the TFT substrate side and
the CF substrate side due to the misalignment of the upper and
lower substrates. As a result, luminance is degraded lower than the
portion in which the misalignment is not generated.
[0066] FIGS. 22A and 22B are views each illustrating the case that
a second conventional liquid crystal panel is bent, FIG. 22A
illustrates the state in which the second conventional liquid
crystal panel is not bent, and FIG. 22B illustrates the state in
which the second conventional liquid crystal panel is bent. As
illustrated in FIG. 22B, the display defect is generated in the
portion in which the misalignment of the first form is generated
and the portion in which the misalignment of the second form is
generated. FIGS. 23A and 23B are views each illustrating the state
of the dark line in a portion in which the misalignment is not
generated in the second conventional liquid crystal panel, FIG. 23A
is a plan view of the pixel, and FIG. 23B is a cross-sectional view
taken along line A-A'. As illustrated in FIGS. 23A and 23B, the
dark line of the type A is generated only in the domain boundary
region. FIGS. 24A and 24B are views each illustrating the state of
the dark line in a portion in which the misalignment of the first
form is generated in the second conventional liquid crystal panel,
FIG. 24A is a plan view of the pixel, and FIG. 24B is a
cross-sectional view taken along line A-A'. As illustrated in FIGS.
24A and 24B, in a portion, in which the second conventional liquid
crystal panel is bent, and the TFT substrate is shifted onto the
left side while the CF substrate is shifted onto the right side,
thereby generating the misalignment of the first form, not only the
dark line of the type A is generated in the domain boundary region,
but also the dark line of the type B generated in the region where
the liquid crystal alignment becomes abnormal is generated by the
mismatching of the alignment controlling regions on the TFT
substrate side and the CF substrate side due to the misalignment of
the upper and lower substrates. As a result, the dark line of the
type A, which is hidden while overlapping the black matrix (light
shielding body) in the state in which the misalignment is not
generated, appears outside the light shielding body, and the
luminance is degraded lower than the portion in which the
misalignment is not generated. FIGS. 25A and 25B are views each
illustrating the state of the dark line in a portion in which the
misalignment of the second form is generated in the second
conventional liquid crystal panel, FIG. 25A is a plan view of the
pixel, and FIG. 25B is a cross-sectional view taken along line
A-A'. As illustrated in FIGS. 25A and 25B, in a portion, in which
the second conventional liquid crystal panel is bent, and the TFT
substrate is shifted onto the right side while the CF substrate is
shifted onto the left side, thereby generating the misalignment of
the second form, not only the dark line of the type A is generated
in the domain boundary region, but also the dark line of the type B
generated in the region where the liquid crystal alignment becomes
abnormal is generated by the mismatching of the alignment
controlling regions on the TFT substrate side and the CF substrate
side due to the misalignment of the upper and lower substrates. As
a result, the dark line of the type A, which is hidden while
overlapping the black matrix (light shielding body) in the state in
which the misalignment is not generated, appears outside the light
shielding body, and the luminance is degraded lower than the
portion in which the misalignment is not generated.
[0067] FIGS. 26A and 26B are views each illustrating the case that
a third conventional liquid crystal panel is bent, FIG. 26A
illustrates the state in which the third conventional liquid
crystal panel is not bent, and FIG. 26B illustrates the state in
which the third conventional liquid crystal panel is bent. As
illustrated in FIG. 26B, the display defect is generated in the
portion in which the misalignment of the first form is generated
and the portion in which the misalignment of the second form is
generated. FIGS. 27A and 27B are views each illustrating the state
of the dark line in a portion in which the misalignment is not
generated in the third conventional liquid crystal panel, FIG. 27A
is a plan view of the pixel, and FIG. 27B is a cross-sectional view
taken along line A-A'. As illustrated in FIGS. 27A and 27B, the
dark line of the type A is generated only in the domain boundary
region. FIGS. 28A and 28B are views each illustrating the state of
the dark line in a portion in which the misalignment of the first
form is generated in the third conventional liquid crystal panel,
FIG. 28A is a plan view of the pixel, and FIG. 28B is a
cross-sectional view taken along line A-A'. As illustrated in FIGS.
28A and 28B, in a portion, in which the third conventional liquid
crystal panel is bent, and the TFT substrate is shifted onto the
left side while the CF substrate is shifted onto the right side,
thereby generating the misalignment of the first form, not only the
dark line of the type A is generated in the domain boundary region,
but also the dark line of the type B generated in the region where
the liquid crystal alignment becomes abnormal is generated by the
mismatching of the alignment controlling regions on the TFT
substrate side and the CF substrate side due to the misalignment of
the upper and lower substrates. As a result, the dark line of the
type A, which is hidden while overlapping the black matrix (light
shielding body) in the state in which the misalignment is not
generated, appears outside the light shielding body. Because the
dark line of the type A appears in the pixel having a specific
color, a color shift is generated as compared with the portion in
which the misalignment is not generated. FIGS. 29A and 29B are
views each illustrating the state of the dark line in a portion in
which the misalignment of the second form is generated in the third
conventional liquid crystal panel, FIG. 29A is a plan view of the
pixel, and FIG. 29B is a cross-sectional view taken along line
A-A'. As illustrated in FIGS. 29A and 29B, in a portion, in which
the third conventional liquid crystal panel is bent, and the TFT
substrate is shifted onto the right side while the CF substrate is
shifted onto the left side, thereby generating the misalignment of
the second form, not only the dark line of the type A is generated
in the domain boundary region, but also the dark line of the type B
generated in the region where the liquid crystal alignment becomes
abnormal is generated by the mismatching of the alignment
controlling regions on the TFT substrate side and the CF substrate
side due to the misalignment of the upper and lower substrates. As
a result, the dark line of the type A, which is hidden while
overlapping the black matrix (light shielding body) in the state in
which the misalignment is not generated, appears outside the light
shielding body. Because the dark line of the type A appears in the
pixel having a specific color, a color shift is generated as
compared with the portion in which the misalignment is not
generated.
[0068] An outline of the configuration of the liquid crystal
display device of the embodiment will be described below. The first
substrate 30 is an active matrix substrate (TFT substrate), and the
active matrix substrate that is commonly used in the field of the
liquid crystal panel can be used as the first substrate 30. FIG. 4
is a schematic plan view illustrating the oblique azimuth of the
liquid crystal molecules 41 in the liquid crystal layer 40 of the
embodiment while the oblique azimuth is superposed on an electrode
and line structure of the first substrate 30. A configuration in
which multiple gate lines G parallel to each other; multiple source
lines S that extend in a direction orthogonal to the gate line G
and are formed in parallel to each other; an active element such as
a TFT 13 disposed at an intersection of the gate line G and the
source line S; multiple drain lines D disposed in the region
sectioned by the gate line G and the source line S; and the pixel
electrodes 35 are provided on a transparent substrate 31 in a plan
view of the first substrate 30. A capacitance line Cs may be
disposed in parallel to the gate line G. In the cross section of
the first substrate 30, an insulating film 32 such as a gate
insulating film and an interlayer insulating film is provided
between the gate line G and the pixel electrode 35.
[0069] A TFT in which a channel is formed using an oxide
semiconductor is suitably used as the TFT 13. Examples of the oxide
semiconductors include a compound (In--Ga--Zn--O) containing indium
(In), gallium (Ga), zinc (Zn), and oxygen (O), a compound
(In--Sn--Zn--O) containing indium (In), tin (Sn), zinc (Zn), and
oxygen (O), and a compound (In--Al--Zn--O) containing indium (In),
aluminum (Al), zinc (Zn), and oxygen (O).
[0070] The pixel electrode 35 is preferably made of a transparent
conductive material. Examples of the transparent conductive
materials include indium tin oxide (ITO) and indium zinc oxide
(IZO).
[0071] Each of the pixel electrodes 35 is superimposed on the first
domain 10a, the second domain 10b, the third domain 10c, and the
fourth domain 10d. Thus, when the voltage is applied to the liquid
crystal layer 40, an electric field having the same magnitude is
applied in a thickness direction of the liquid crystal layer 40 in
the first domain 10a, the second domain 10b, the third domain 10c,
and the fourth domain 10d.
[0072] Multiple fine slits 36 parallel to the alignment vectors of
the first, second, third, and fourth domains 10a, 10b, 10c, 10d
superimposed on the pixel electrodes 35 are provided in each of the
pixel electrodes 35. As used herein, the fine slits mean multiple
pairs in each of which the slit portion (opening portion) and
electrode that extend in a direction parallel to the desired
alignment direction (alignment vector) of the liquid crystal are
paired. The fine slits 36 generate electric field distortion having
a groove-shaped equipotential surface parallel to the extending
direction of the slit portion. The electric field formed by the
fine slits 36 has a lateral electric field component that is
parallel to the substrate surface and is perpendicular to the
extending direction of the slit portion. The alignment direction of
the liquid crystal molecules 41 changes due to the lateral electric
field component, and the liquid crystal molecules 41 are aligned in
parallel to the slit.
[0073] In the first substrate 30, the pixel electrode 35 is
disposed in each pixel 10, and at least one gate line G extends
between the nth row pixel and the (n+1)th row pixel. The domains in
the nth row pixel are arranged in the order of the first domain
10a, the second domain 10b, the third domain 10c, and the fourth
domain 10d. Thus, in the nth row pixel, the first domain 10a and
the fourth domain 10d are adjacent to the gate line G. In the nth
row pixel, a region where the fine slits 36 do not exist is
provided at ends 35E1 and 35E2 parallel to the row direction of the
pixel electrode 35, and a region where the fine slits 36 do not
exist is provided at ends 35E3 and 35E4 parallel to the column
direction of the pixel electrode 35. The portion having the largest
width of the region where the fine slits 36 do not exist is
included in both the ends 35E1 and 35E2 parallel to the row
direction of the pixel electrode 35. The term "the width of the
region where the fine slits 36 do not exist" corresponds to a
distance from an end 365 in a longitudinal direction of the fine
slit 36 to an outer edge of the pixel electrode 35. The end 365 in
the longitudinal direction of the fine slit 36 is separated from
the ends 35E1 and 35E2 on the side adjacent to the gate line G of
the pixel electrode 35, whereby the influence of the voltage (gate
voltage) of the gate signal applied to the gate line G on the
inside of the liquid crystal layer 40 through the slit portion of
the fine slit 36 can be reduced to suppress the display unevenness.
In one of the first domain 10a and the fourth domain 10d, the
effect that the display unevenness is suppressed is obtained when
the end 36E in the longitudinal direction of the fine slit 36 is
disposed away from the ends 35E1 and 35E2 on the side adjacent to
the gate line G of the pixel electrode 35. As illustrated in FIG.
4, in both the first domain 10a and the fourth domain 10d, it is
more effective that the end 36E in the longitudinal direction of
the fine slit 36 is disposed away from the ends 35E1 and 35E2 on
the side adjacent to the gate line G of the pixel electrode 35.
[0074] The distance from the end 36E in the longitudinal direction
of the fine slit 36 to the ends 35E1 and 35E2 on the side adjacent
to the gate line G of the pixel electrode 35 in the first domain
10a and the fourth domain 10d ranges preferably from 5 .mu.m to 25
.mu.m inclusive. The influence of the gate voltage on the liquid
crystal layer 40 can sufficiently be reduced by setting the
distance to 5 .mu.m or more. A decrease in transmittance can be
prevented by setting the distance to 25 .mu.m or less.
[0075] In a plan view of the first substrate 30, the distance from
the end 36E in the longitudinal direction of the fine slit 36 to
the gate line G in the first domain 10a and the fourth domain 10d
ranges preferably from 5 .mu.m to 25 .mu.m inclusive. The influence
of the gate voltage on the liquid crystal layer 40 can sufficiently
be reduced by setting the distance to 5 .mu.m or more. A decrease
in transmittance can be prevented by setting the distance to 25
.mu.m or less.
[0076] Preferably a width (space) and a pitch (line+space) of the
fine slits 36 satisfy the following conditions. [0077] width
(space) of fine slit 36.ltoreq.5.1 .mu.m [0078] pitch (line+space)
of fine slit 36.ltoreq.11 .mu.m
[0079] More preferably the width (space) and the pitch (line+space)
of the fine slits 36 satisfy the following conditions. [0080] width
(space) of the fine slit 36.ltoreq.4.3 .mu.m [0081] pitch
(line+space) of fine slit 36.ltoreq.8.3 .mu.m
[0082] As illustrated in FIG. 4, the domains in the (n+1)th row
pixel satisfy the relationship in which the first domain 10a and
the fourth domain 10d are located between the second domain 10b and
the third domain 10c. Thus, in the (n+1)th row pixel, the second
domain 10b and the third domain 10c are adjacent to the gate line
G. Even in the (n+1) th row pixel, the region where the fine slits
36 do not exist is provided at the ends 35E1 and 35E2 parallel to
the row direction of the pixel electrode 35, and the region where
the fine slits 36 do not exist is provided at the ends 35E3 and
35E4 parallel to the column direction of the pixel electrode 35.
The portion having the largest width of the region where the fine
slits 36 do not exist is included in both the ends 35E1 and 35E2
parallel to the row direction of the pixel electrode 35. In one of
the second domain 10b and the third domain 10c, the effect that the
display unevenness is suppressed is obtained when the end 36E in
the longitudinal direction of the fine slit 36 is disposed away
from the ends 35E1 and 35E2 on the side adjacent to the gate line G
of the pixel electrode 35. As illustrated in FIG. 4, in both the
second domain 10b and the third domain 10c, it is more effective
that the end 36E in the longitudinal direction of the fine slit 36
is disposed away from the ends 35E1 and 35E2 on the side adjacent
to the gate line G of the pixel electrode 35.
[0083] In the domain arrangement of FIGS. 2 and 4, in the nth row
pixel, the first domain 10a and the fourth domain 10d are located
on the end side of the pixel, and the second domain 10b and the
third domain 10c are located on the center side of the pixel In the
(n+1)th row pixel, the second domain 10b and the third domain 10c
are located on the end side of the pixel, and the first domain 10a
and the fourth domain 10d are located on the center side of the
pixel. FIGS. 5A and 5B are views in which all domains included in
the nth row pixel and the (n+1)th row pixel are organized based on
an adjacent relationship with respect to the gate line G, FIG. 5A
illustrates a domain group that is not adjacent to the gate line G,
and FIG. 5B illustrates a domain group adjacent to the gate line G;
As illustrated in FIGS. 5A and 5B, each of the domain group that is
not adjacent to the gate line G and the domain group adjacent to
the gate line G is constructed with a combination of the first
domain 10a, the second domain 10b, the third domain 10c, and the
fourth domain 10d that face in directions different from one
another by 90.degree.. Consequently, the influence on the liquid
crystal voltage generated in the domains adjacent to the gate line
G can uniformly be dispersed in the first domain 10a, the second
domain 10b, the third domain 10c, and the fourth domain 10d to
suppress the generation of the display unevenness having the
viewing angle dependency.
[0084] The color filter substrate (CF substrate) can be used as the
second substrate 50. A configuration in which the black matrix
formed into a lattice shape and a lattice, namely, the color filter
formed inside the pixel 10 are provided on the transparent
substrate can be cited as the configuration of the color filter
substrate. The black matrix may be formed into the lattice shape in
each pixel so as to overlap the boundary of the pixel 10, or formed
into the lattice shape in each half pixel so as to cross the center
of one pixel along the short-side direction. When the black matrix
is formed so as to overlap the region where dark line is generated,
the dark line is hardly observed, and the influence of the dark
line on the display can be minimized.
[0085] The counter electrode 51 is disposed so as to be opposed to
the pixel electrode 35 with the liquid crystal layer 40 interposed
therebetween. The vertical electric field is formed between the
counter electrode 51 and the pixel electrode 35 and the liquid
crystal molecules 41 are inclined, which allows the display to be
performed. For example, in each column, the color filters may be
arranged in the order of red (R), green (G), and blue (B), in the
order of yellow (Y), red (R), green (G), and blue (B), or in the
order of red (R), green (C), blue (B), and green (G).
[0086] Preferably the counter electrode 51 is a planar electrode.
The counter electrode 51 may be a transparent electrode. For
example, the counter electrode 51 can be made of a transparent
conductive material such as indium tin oxide (ITO), indium zinc
oxide (IZO), zinc oxide (ZnO), and tin oxide (SnO) or an alloy
thereof.
[0087] In the liquid crystal panel 100 of the embodiment, the first
substrate 30 and the second substrate 50 are bonded together by the
sealing material 80 that is provided so as to surround the liquid
crystal layer 40, and the liquid crystal layer 40 is held in a
predetermined region. For example, an epoxy resin containing an
inorganic filler or an organic filler and a hardener can be used as
the sealing material 80.
[0088] A polymer sustained alignment (PSA) technique may be used in
the embodiment. In the PSA technique, a liquid crystal composition
containing a photopolymerizable monomer is filled between the first
substrate 30 and the second substrate 50, the liquid crystal layer
40 is irradiated with light to polymerize the photopolymerizable
monomer, a polymer is formed on the surfaces of the first alignment
film 71 and the second alignment film 72, and the initial
inclination (pre-tilt) of the liquid crystal is fixed by the
polymer.
[0089] As illustrated in FIG. 2, a polarization axis of the
back-side polarizing plate 20 and a polarization axis of the
display-side polarizing plate 60 may be orthogonal to each other.
The polarization axis may be an absorption axis or a transmission
axis of the polarizing plate. Typically, the back-side polarizing
plate 20 and the display-side polarizing plate 60 are those
obtained by adsorbing and aligning an anisotropic material such as
a dichroic iodine complex onto a polyvinyl alcohol (PVA) film.
Usually, a protective film such as a triacetyl cellulose film is
laminated on both sides of the PVA film, and put into practical
use. An optical film such as a retardation film may be disposed
between the back-side polarizing plate 20 and the first substrate
30 and between the display-side polarizing plate 60 and the second
substrate 50.
[0090] Any backlight that emits the light including visible light,
any backlight that emits the light including only the visible
light, or any backlight that emits the light including both the
visible light and ultraviolet light may be used as the backlight
110. A backlight that emits white light is suitably used in order
to perform color display on the liquid crystal display device. For
example, a light emitting diode (LED) is suitably used as a type of
the backlight 110. As used herein, the term "visible light" means
light (electromagnetic wave) having a wavelength that is greater
than or equal to 380 nm and less than 800 nm.
[0091] In addition to the liquid crystal panel 100 and the
backlight 110, the liquid crystal display device of the embodiment
includes an external circuit such as a tape-carrier package (TCP)
and a printed circuit board (PCB); an optical film such as a
viewing angle increasing film and a luminance improving film; and a
bezel (frame). Some components may be incorporated into another
component. Components other than those described above are not
particularly limited and are not described here because such
components can be those commonly used in the field of liquid
crystal display devices.
[0092] The pixel electrode 35 in FIGS. 4 and 5B is provided with
notches at four corners, but may be formed into a substantially
rectangular shape. Consequently, as in the pixel electrode 35A in
FIG. 6, the planar shapes of the first domain 10a and the fourth
domain 10d can be formed into the same substantially rectangular
shape as the planar shapes of the second domain 10b and the third
domain 10c. FIG. 6 is a view illustrating a modification of the
pixel electrode 35 in FIG. 5B.
[0093] FIG. 7 is a schematic plan view illustrating an arrangement
relation of the oblique azimuth of the liquid crystal molecules 41
in the liquid crystal layer 40 and the color filter of the second
substrate 50 of the modification. In the liquid crystal panel 100
of FIGS. 2 and 4, the domain array in the nth row pixel and the
domain array in the (n+1)th row pixel are made different from each
other, and the combination of the four domains included in the
domain group that is not adjacent to the gate line G and the
combination of the four domains included in the domain group
adjacent to the gate line G are matched with each other.
Alternatively, as illustrated in FIG. 7, the domains in all the
pixels 10 may be arranged in the order of the first domain 10a, the
second domain 10b, the third domain 10c, and the fourth domain 10d.
That is, in all the pixels 10, the first domain 10a and the fourth
domain 10d may be adjacent to the gate line G, and the second
domain 10b and the third domain 10c may not be adjacent to the gate
line G. Even in this case, in all the pixels 10, the influence of
the gate voltage on the liquid crystal voltage can be suppressed
when the end 36E in the longitudinal direction of the fine slit 36
in the first domain 10a and the fourth domain 10d is disposed away
from the ends 35E1 and 35E2 on the side adjacent to the gate line G
of the pixel electrode 35.
[0094] In the liquid crystal panel 100 of the embodiment, the
generation of the display unevenness having the viewing angle
dependency can be suppressed. The reason is as follows.
[0095] In the liquid crystal panel 100 during the display, the
voltage is applied to the liquid crystal layer 40 through the pixel
electrode 35. In the case that the fine slits 36 are provided in
the pixel electrode 35, the gate line voltage (gate voltage)
applied to the gate line G through the slit portion also influences
the inside of the liquid crystal layer 40. FIG. 13 is a waveform
chart schematically illustrating an example of a waveform of the
voltage applied to a general liquid crystal panel. As illustrated
in FIG. 13, because usually the value and the waveform of the gate
voltage (-5 V to 25 V) are largely different from the value and the
waveform of the voltage (0 V to +15 V) applied to the liquid
crystal layer 40 through the pixel electrode 35, the inside of the
liquid crystal layer 40 is influenced through the slit portion even
if the gate line G is separated from the liquid crystal layer 40 by
the insulating film 32 such as the gate insulating film and the
interlayer insulating film. Because a degree of influence by the
gate voltage varies depending on the distance from the gate line G,
the domain that is not adjacent to the gate line G and the domain
adjacent to the gate line G are different from each other in the
degree of influence by the gate voltage. In a general pixel
structure, while the domain adjacent to the gate line G is
influenced by the gate line G, the influence of the gate line G on
the domain that is not adjacent to the gate line G is negligibly
small, namely, substantially zero. In the domain adjacent to the
gate line G, because the degree of influence of the gate voltage
varies depending on the variation in line width of the slit portion
and the variation in width of the gate line, a difference in
luminance is generated, and the display unevenness is
generated.
[0096] For this reason, in the embodiment, in one of the first
domain 10a and the fourth domain 10d, the end 36E in the
longitudinal direction of the fine slit 36 is disposed away from
the ends 35E1 and 35E2 on the side adjacent to the gate line G of
the pixel electrode 35 as illustrated in FIG. 4. Consequently, the
influence on the liquid crystal voltage generated in the domain
adjacent to the gate line G can be reduced to suppress the
generation of the display unevenness having the viewing angle
dependency.
[0097] A method of manufacturing the liquid crystal panel 100 of
the embodiment will be described below. The method of manufacturing
the liquid crystal panel 100 of the embodiment is not particularly
limited, but a method usually used in the field of the liquid
crystal panel can be adopted. The gate line G and the pixel
electrode 35 that are provided on the first substrate 30 and the
color filter provided on the second substrate 50 can be formed by
photolithography.
[0098] From the viewpoints of patterning accuracy and productivity,
the photolithography is suitably used as the method of forming the
pixel electrode 35 having the fine slits 36. In the case that the
fine slits 36 are formed by the photolithography, a photosensitive
resin (photoresist) formed on the conductive film that constitutes
a material of the pixel electrode 35 is irradiated with light
through a mask having a pattern corresponding to the fine slits 36.
The photoresist may be irradiated with the light through multiple
lenses (multi-lens).
[0099] The case that the photoresist is irradiated with the light
used for the patterning of the fine slits 36 through the multi-lens
will be described with reference to the drawings. FIG. 8 is a view
illustrating the photolithography using the multi-lens. As
illustrated in FIG. 8, exposure is performed on a substrate 170
through a mask 150 including a pattern formation region 151 where a
light shielding pattern or a light transmitting pattern
corresponding to the fine slit 36 is formed and a multi-lens 160
including the lenses. A substrate on which a photoresist 172 is
formed on a conductive film 171 that constitutes the material of
the pixel electrode 35 is used as the substrate 170. An exposure
system is preferably scanning exposure that is performed while at
least one of an exposure unit including the mask 150 and the
multi-lens 160 and the substrate 170 is moved. Development of the
photoresist 172, etching of the conductive film 171, and peeling of
the photoresist 172 are sequentially performed after the
exposure.
[0100] When the exposure is performed using the multi-lens 160, a
focal point or illuminance of each lens may vary. FIG. 9A is a
schematic cross-sectional view illustrating an arrangement relation
of lenses 160A, 160B, 160C, 160D, 160E in the multi-lens 160, and
FIG. 9B is a conceptual view illustrating a pattern of the
luminance unevenness generated when the pixel electrode 35
including fine slits 36 and the gate line G are formed by the
scanning exposure in which the multi-lens 160 in FIG. 9A is used.
In the case that a difference in a focal point or illuminance
exists among the lenses 160A, 160B, 160C, 160D, 160E when the
scanning exposure is performed with the arrangement of the lenses
160A, 160B, 1600, 160D, 160E in FIG. 9A, the line width of the fine
slits 36 and the width of the gate line vary in exposure regions
172A, 172B, 172C, 172D, 172E corresponding to the lenses 160A,
160B, 160C, 160D, 160E as illustrated in FIG. 9k. As a result, the
luminance of the liquid crystal panel 100 varies in each of the
exposure regions 172A, 172B, 172C, 172D, 172E, and is sometimes
recognized as the display unevenness. In particular, because the
boundary between the adjacent exposure regions 172A, 172B, 172C,
172D, 172E is a portion in which the line width of the fine slits
36 and the width of the gate line change, the boundary is
recognized as seam-shaped display unevenness to degrade the display
quality of the liquid crystal panel 100.
[0101] On the other hand, in the liquid crystal panel 100 of the
embodiment, as described above, the voltage of the gate signal
applied to the gate line G acts in the liquid crystal layer 40
through the slit portion, whereby the generation of the display
unevenness is reduced by adjusting the arrangement of the fine
slits 36. Thus, the influence of the variation in line width of the
fine slits 36 on the display quality is also suppressed. In the
case that the domain array in the nth row pixel and the domain
array in the (n+1)th row pixel are different from each other,
because a repeating unit of the domain array is not one row (four
domains) but two rows (eight domains), the boundary between the
exposure regions 172A, 172B, 172C, 172D, 172F is hardly recognized
as the seam-shaped display unevenness as compared with the case
that the domain arrays of each row are equal to each other.
[0102] A photo alignment film can also be used for one or both of
the first alignment film 71 and the second alignment film 72. In
this case, the alignment treatment performed on the photo alignment
film can be performed by the photo alignment treatment in which the
photo alignment film is irradiated with light (electromagnetic
wave) such as ultraviolet light and visible light. For example, the
photo alignment treatment is performed using a device, which
includes a light source that emits the light to the first alignment
film 71 and the second alignment film 72 and has a function of
performing continuous scanning exposure over the pixels. Examples
of specific modes of the scanning exposure include a mode in which
a substrate surface is irradiated with the light emitted from the
light source while the substrate is moved, a mode in which the
substrate surface is irradiated with the light emitted from the
light source while the light source is moved, and a mode in which
the substrate surface is irradiated with the light emitted from the
light source while the light source and the substrate are
moved.
[0103] A specific example of the alignment treatment will be
described below. FIG. 10 is a schematic diagram illustrating an
example of the photo alignment treatment device. A photo alignment
treatment device 200 in FIG. 10 performs the photo alignment
treatment on the photo alignment film formed on the liquid crystal
panel substrate. Although the first alignment film 71 formed on the
first substrate (liquid crystal panel substrate) 30 is illustrated
in FIG. 10, the second alignment film 72 can also be processed. The
photo alignment treatment device 200 includes a light irradiation
mechanism 280 and a stage 250 on which the liquid crystal panel
substrate 30 is placed.
[0104] The light irradiation mechanism 280 includes a light source
220, a polarizer 230, and a rotation adjustment mechanism 260. The
light source 220 and the polarizer 230 may be disposed in a lamp
box 270. A type of the light source 220 is not particularly
limited, but a light source typically used in the field of the
photo alignment treatment device can be used. For example, a
low-pressure mercury lamp, a deuterium lamp, a metal halide lamp,
an argon resonance lamp, and a xenon lamp can be used.
[0105] Light 221 emitted from the light source 220 may be light
(electromagnetic wave) such as ultraviolet light and visible light,
and the light 221 preferably has a wavelength of 280 nm to 400
nm.
[0106] For example, the polarizer 230 extracts linearly polarized
light from the light emitted from the light source 220 toward the
liquid crystal panel substrate 30. The polarization axis means to
transmission axis or an absorption axis of the polarizer. Examples
of the polarizer 230 include an organic resin polarizer, a wire
grid polarizer, and a polarizing beam splitter (PBS).
[0107] A polarizer obtained by adsorbing iodine in polyvinyl
alcohol and extending polyvinyl alcohol in a sheet shape can be
cited as an example of the organic resin polarizer.
[0108] For example, the wire grid polarizer includes a light
transmission base material and multiple metal thin wires formed on
the light transmission base material, and the metal thin wires are
disposed in a period shorter than the wavelength of light incident
on the wire grid polarizer. The metal thin wire is made of a light
absorbing metal material such as chromium. When the wire grid
polarizer is irradiated with the light while superimposed on the
liquid crystal panel substrate 30, the liquid crystal molecules are
aligned at the azimuth orthogonal to an extending azimuth of the
metal thin wire. In the case that the polarizer 230 is the wire
grid polarizer, the polarization axis is the azimuth orthogonal to
the extending azimuth of the metal thin wire. Alignment division
treatment can efficiently be performed using the wire grid
polarizer having a different extending azimuth of the metal thin
wire.
[0109] A cube type polarization beam splitter or a plate type
polarization beam splitter can be cited as an example of the
polarization beam splitter. A PBS, in which slopes of two prisms
are bonded together and an optical thin film is evaporated on one
of the slopes, can be cited as an example of the cube type PBS.
[0110] The polarizer 230 may be disposed perpendicular to the light
irradiation axis. In the case that the polarizer 230 is not
disposed perpendicularly to the light irradiation axis, sometimes
the alignment of the liquid crystal molecules is influenced by a
waveguide effect in the polarizer 230. The light irradiation axis
is a direction in which the light 221 emitted from the light source
220 toward the liquid crystal panel substrate 30 propagates
linearly. The disposition of the polarizer perpendicular to the
light irradiation axis means that the polarizer is disposed such
that the light is emitted from a normal direction of the polarizer
toward the liquid crystal panel substrate, and the term
"perpendicular" means a range in which an angle formed between the
normal line of the polarizer and the light irradiation axis is less
than 0.5.degree..
[0111] A wavelength selection filter 235 may be included between
the light source 220 and the polarizer 230. A main wavelength of
the light emitted through the wavelength selection filter 235 may
range from 280 nm to 400 nm. The selection wavelength of 280 nm to
400 nm can generate a structural chance of a material, which
constitutes the first alignment film 71 and exhibits the photo
alignment characteristic, and exert the alignment controlling
force. Intensity of the light emitted from the light source may
range from 10 mJ/cm.sup.2 to 100 mJ/cm.sup.2.
[0112] The wavelength selection filter 235 is not particularly
limited, and a wavelength selection filter typically used in the
field of the photo alignment treatment device can be used. A
wavelength selection filter in which a substance absorbing a
wavelength other than the transmission wavelength is dispersed in
the filter or a wavelength selection filter in which a substance
reflecting a wavelength other than the transmission wavelength is
coated on the surface of the filter can be cited as an example of
the wavelength selection filter 235.
[0113] The light irradiation angle with respect to the liquid
crystal panel substrate 30 may range from 30.degree. to 60.degree..
The irradiation angle is represented by .theta.1 in FIG. 11, and is
an angle formed between a plane of the liquid crystal panel
substrate 30 and the light irradiation axis in the case that the
surface of the liquid crystal panel substrate 30 is set to
0.degree. and in the case that the normal line of the liquid
crystal panel substrate 30 is set to 90.degree..
[0114] An extinction ratio of the polarizer may range from 50:1 to
500:1. The extinction ratio is represented by Tmax:Tmin, where Tmax
is maximum transmittance in the case that the polarizer is
irradiated with the light and Tmin is minimum transmittance
obtained by rotating the polarizer by 90.degree.. The light in the
desired polarization axis direction is taken out with increasing
extinction ratio (a value of Tmax in the case that Tmin is set to
1), so that a variation in oblique azimuth of the liquid crystal
molecules can be reduced.
[0115] The rotation adjustment mechanism 260 rotates a polarization
axis 231 of the polarizer 230, and adjusts an exposure direction
253 on the surface of the liquid crystal panel substrate 30 so as
to substantially become 45.degree. with respect to a light
irradiation direction 252. By setting the exposure direction 253 to
substantially 45.degree. with respect to the light irradiation
direction 252, the photo alignment treatment can be performed on
the liquid crystal panel substrate 30 by scanning exposure having
excellent productivity while a movement direction 251 of the liquid
crystal panel substrate 30 is kept in parallel to the light
irradiation direction 252. As illustrated in FIG. 10, the light
irradiation direction 252 means a light traveling direction in the
case that the light 221 emitted from the light source 220 is
projected onto the surface of the liquid crystal panel substrate
30. The exposure direction 253 means a vibration direction of
polarized light emitted from the light source 220 to the surface of
the liquid crystal panel substrate 30 through the polarizer 230. A
pre-tilt azimuth that the alignment film 70 formed on the surface
of the liquid crystal panel substrate 30 provides to the liquid
crystal molecules is fixed by the exposure direction 253.
[0116] For example, the polarization axis 231 is adjusted using the
rotation adjustment mechanism 260 by the following method. The
polarizer 230 is set such that the polarization axis 231 becomes
45.degree. with respect to the light irradiation direction 252. The
azimuth of the polarization axis before the polarization axis is
adjusted by the rotation adjustment mechanism is also referred to
as "a 45.degree. azimuth". Subsequently, the rotation adjustment
mechanism 260 rotates the polarizer 230 from the 45.degree. azimuth
to adjust the azimuth of the polarization axis 231 based on data
calculated by geometric computation in consideration of the light
irradiation angle with respect to the liquid crystal panel
substrate and a refractive index of the alignment film material.
The rotation adjustment mechanism 260 can match the azimuth of the
polarization axis of the polarizer with respect to the light
irradiation direction with the exposure direction on the surface of
the liquid crystal panel substrate to set the oblique azimuth of
the liquid crystal molecules in the liquid crystal panel to a
desired angle. When the photo alignment treatment is performed with
no use of the rotation adjustment mechanism 260 while the
polarization axis 231 is fixed to the 45.degree. azimuth, sometimes
the oblique azimuth of the liquid crystal molecules deviates by
about 10.degree. from about 45.degree..
[0117] The rotation adjustment mechanism 260 may rotate the
polarization axis of the polarizer 230 in the range of -15.degree.
to +15.degree. from the 45.degree. azimuth. When the rotation
adjustment mechanism 260 rotates the polarization axis in the range
of -15.degree. to +15.degree., even if the light irradiation angle
is changed with respect to the liquid crystal panel substrate 30,
the exposure direction 253 can be adjusted to set the oblique
azimuth of the liquid crystal molecules to the desired angle. For
example, the polarization axis 231 is rotated from the 45.degree.
azimuth by +7.55.degree. and set to 52.55.degree. in order to
adjust the exposure direction 253 on the surface of the liquid
crystal panel substrate to substantial 45.degree. with respect to
the light irradiation direction 252.
[0118] The photo alignment treatment device 200 may further include
a rotation mechanism 264. The rotation mechanism 264 can rotate the
polarization axis 231 of the polarizer 230 by selecting either
substantial 45.degree. or substantial 90.degree. from the
45.degree. azimuth. In the case that the azimuth of 45.degree. is
set to the +45.degree. azimuth clockwise with respect to the light
irradiation direction 252, the rotated polarization axis 231
becomes the -45.degree. azimuth with respect to the light
irradiation direction 252 when the polarization axis 231 of the
polarizer 230 is rotated by 90.degree. from the +45.degree.
azimuth. The polarization axis 231 is rotated by 90.degree. from
the +45.degree. azimuth and adjusted by the rotation adjustment
mechanism 260, which allows the light irradiation to be performed
while the exposure direction 253 is set to substantial 45.degree.
with respect to the light irradiation direction 252 before and
after the rotation. Consequently, the embodiment is suitable for
manufacturing a liquid crystal panel having an alignment control
mode, in which four alignment regions having mutually different
oblique azimuths of the liquid crystal molecules are arranged along
a longitudinal direction of the pixel as illustrated in FIG. 2. The
liquid crystal panel having the new alignment control mode can be
manufactured by the scanning exposure, so that production
efficiency can greatly be improved. The term "substantial
45.degree. or substantial 90.degree. from the 45.degree. azimuth"
means a range of an angle of 15.degree. clockwise or
counterclockwise from 45.degree. or 90.degree. with respect to the
45.degree. azimuth, respectively. The 45.degree. azimuth and the
90.degree. azimuth refer to a range of .+-.0.5.degree. from
45.degree. and 90.degree., respectively.
[0119] The rotation mechanism 264 can also rotate the polarization
axis 231 of the polarizer 230 from the 45.degree. azimuth to
substantial 45.degree.. When the polarization axis 231 is rotated
by 45.degree. from the 45.degree. azimuth, the rotated polarization
axis 231 is parallel to the light irradiation direction, so that
the conventional photo alignment treatment in which the
polarization axis of the polarizer is matched with the light
irradiation direction can also be performed.
[0120] The stage 250 is a stage on which the liquid crystal panel
substrate 30 is placed. The liquid crystal panel substrate 30 is
fixed onto the stage 250, and the liquid crystal panel substrate 30
is irradiated with the light while the liquid crystal panel
substrate 30 is moved, or the liquid crystal panel substrate 30 is
irradiated with the light while the light source is moved with
respect to the liquid crystal panel substrate 30. The photo
alignment treatment can efficiently be performed by performing the
scanning exposure. The light irradiation direction with respect to
the liquid crystal panel substrate 30 is parallel to the movement
direction of the liquid crystal panel substrate 30 or the movement
direction of the light source 220, and an incident angle of light
incident on the substrate from the light source becomes
substantially the same in a light irradiation area of the light
source, so that a pre-tilt angle (polar angle) provided to the
liquid crystal molecules also becomes substantially the same. For
this reason, a variation in pre-tilt angle can be suppressed in the
light irradiation area to manufacture the liquid crystal panel
having excellent display quality. The photo alignment treatment
device 200 may include a stage scanning mechanism that moves the
stage 250 and/or a light source scanning mechanism that moves the
light source 220. The term "parallel" includes a range in which the
angle formed between the light irradiation direction and the
movement direction of the liquid crystal panel substrate 30 or the
movement direction of the light source 220 is less than
5.degree..
[0121] The photo alignment treatment device 200 may include a light
shielding member 240 in addition to the stage scanning mechanism
and/or the light source scanning mechanism. The alignment division
treatment can be performed by performing the photo alignment
treatment while a portion that is not irradiated with the light is
shielded by the light shielding member 240.
[0122] The use of the photo alignment treatment device can match
the azimuth of the polarization axis of the polarizer with respect
to the light irradiation direction with the exposure direction on
the surface of the liquid crystal panel substrate to set the
oblique azimuth of the liquid crystal molecules 41 in the liquid
crystal panel 100 to the desired angle.
[0123] An example of a photo alignment treatment step using the
photo alignment treatment device 200 will be described below with
reference to FIG. 11. FIG. 11 is a view illustrating an example of
the photo alignment treatment step using the photo alignment
treatment device. The photo alignment treatment step in FIG. 11 is
an example in which, using the light irradiation mechanism 280
including one polarizer 230, the polarization axis 231 of the
polarizer 230 is rotated by the rotation mechanism 264 to perform
the photo alignment treatment. In FIG. 11, in order to describe the
azimuth of the liquid crystal panel substrate 30, a notch is
illustrated in one corner. However, the actual liquid crystal panel
substrate 30 may not include the notch.
[0124] As illustrated in FIG. 11, the movement direction 251 of the
liquid crystal panel substrate 30 is set to the first direction,
the light irradiation direction 252 is set to the second direction,
and the first-time light irradiation is performed through the
wavelength selection filter 235 (not illustrated) and the polarizer
230 using the light irradiation mechanism 280. The first direction
and the second direction are parallel to each other. The region
that is not irradiated with the light is shielded by the light
shielding member 240. The polarization axis 231 of the polarizer
230 is set to the +45.degree. azimuth clockwise with respect to the
light irradiation direction 252, and then the rotation adjustment
mechanism 260 adjusts the exposure direction 253 on the surface of
the liquid crystal panel substrate 30 to substantial 45.degree.
with respect to the light irradiation direction 252 to perform the
first-time light irradiation. Subsequently, the light shielding
member 240 is moved, the polarization axis 231 of the polarizer 230
is rotated by 90.degree. from the +45.degree. azimuth by the
rotation mechanism 264 and set to the -45.degree. azimuth
counterclockwise with respect to the light irradiation direction
252, and then the polarization axis 231 is adjusted by the rotation
adjustment mechanism 260 to perform the second-time light
irradiation. Subsequently, the substrate is rotated by 180.degree.,
the light shielding member 240 is further moved, the polarizer 230
is rotated by 90.degree. from the -45.degree. azimuth by the
rotation mechanism 264 and set to the +45.degree. azimuth, and then
the polarization axis 231 is adjusted by the rotation adjustment
mechanism 260 to perform the third-time light irradiation. Finally,
the light shielding member 240 is moved, the polarizer 230 is
rotated by 90.degree. from the +45.degree. azimuth by the rotation
mechanism 264 and set to the -45.degree. azimuth, and then the
polarization axis 231 is adjusted by the rotation adjustment
mechanism 260 to perform the fourth-time light irradiation. In the
liquid crystal panel substrate 30 subjected to the light
irradiation step, a pre-tilt azimuth 253 varies in each of regions
corresponding to the four alignment regions formed in one pixel.
The movement direction 251 and the light irradiation direction 252
of the liquid crystal panel substrate 30 are the same in all the
first-time light irradiation to the fourth-time light irradiation.
In all the first-time light irradiation to the fourth-time light
irradiation, the polarization axis 231 is adjusted by the rotation
adjustment mechanism 260 such that the exposure direction 253 on
the surface of the liquid crystal panel substrate 30 becomes
substantial 45.degree. with respect to the light irradiation
direction 252.
[0125] FIG. 12A is a view illustrating the photo alignment
treatment performed on the TFT substrate (first substrate), FIG.
12B is a view illustrating the photo alignment treatment performed
on the CF substrate (second substrate), and FIG. 12C is a view
illustrating a state after bonding of the TFT substrate and the CF
substrate that, are subject to the photo alignment treatment; As
illustrated in FIG. 12A, the TFT substrate (first substrate) 30 is
subjected to the photo alignment treatment by changing the pre tilt
azimuth 253 in each domain by the first-time light irradiation to
the fourth-time light irradiation. In the same manner as in the TFT
substrate, as illustrated in FIG. 12B, the CF substrate (second
substrate) 50 is also subjected to the photo alignment treatment by
changing a pre-tilt azimuth 254 in each domain by the first-time
light irradiation to the fourth-time light irradiation. As
illustrated in FIG. 12C, the first domain 10a, the second domain
10b, the third domain 10c, and the fourth domain 10d that are
included in the liquid crystal panel 100 of the embodiment are
completed when the TFT substrate 30 and the CF substrate 50 that
are subjected to the photo alignment treatment are bonded
together.
[Additional Remarks]
[0126] According to one aspect of the present invention, there is
provided a liquid crystal panel including, in the following order:
a first substrate including multiple pixel electrodes arranged into
a matrix form, multiple gate lines, and a first alignment film; a
liquid crystal layer containing liquid crystal molecules; and a
second substrate including a common electrode and a second
alignment film, wherein an alignment vector is defined as being
from a first substrate side long-axis end of each of the liquid
crystal molecules, a start point, to a second substrate side
long-axis end of the liquid crystal molecule, an end point, and the
first alignment film and the second alignment film having been
subjected to an alignment treatment each include multiple domains
with different alignment vectors in a column direction in each
display unit region superimposed on one of the pixel electrodes, in
at least 30 pixels consecutive in a row direction, arrays of the
domains are identical, the gate lines extend through a region
between rows of the display unit regions, the domains in the
display unit region located in an nth row, where n is any integer
of 1 or more, are arranged in an order of a first domain in which a
direction of the alignment vector is a first direction, a second
domain in which a direction of the alignment vector is a second
direction, a third domain in which a direction of the alignment
vector is a third direction, and a fourth domain in which a
direction of the alignment vector is a fourth direction, each of
the pixel electrodes is provided, in the first domain, the second
domain, the third domain, and the fourth domain, with multiple fine
slits parallel to the alignment vectors of the respective domains,
each of the pixel electrodes includes a region where the fine slits
do not exist, at both ends of the pixel electrode parallel to the
row direction and at one or both of ends of the pixel electrode
parallel to the column direction, and a portion having a largest
width of the region where the fine slits do not exist is included
in one or both of the ends of the pixel electrode parallel to the
row direction.
[0127] In the above aspect, in a plan view of the display unit
region located in the nth row, the alignment vector of the first
domain and the alignment vector of the second domain may have a
relationship in which the end points are opposed to each other and
the alignment vectors are orthogonal to each other, the alignment
vector of the second domain and the alignment vector of the third
domain may have a relationship in which the start points are
opposed to each other and the alignment vectors are parallel to
each other, and the alignment vector of the third domain and the
alignment vector of the fourth domain may have a relationship in
which the end points are opposed to each other and the alignment
vectors are orthogonal to each other.
[0128] The liquid crystal molecules may be aligned substantially
vertically to the first substrate and the second substrate when no
voltage is applied to the liquid crystal layer, and the liquid
crystal molecules may obliquely be aligned so as to be matched with
the alignment vectors of the domains when voltage is applied to the
liquid crystal layer.
[0129] In the domains, an inter-substrate twist angle of the liquid
crystal molecules may be less than or equal to 45.degree..
[0130] Each of the first domain, the second domain, the third
domain, and the fourth domain may have a substantially rectangular
shape.
[0131] The domains in the display unit region located in the
(n+1)th row adjacent to the nth row with at least one of the gate
lines interposed therebetween may satisfy a relationship in which
the first domain and the fourth domain are located between the
second domain and the third domain.
[0132] The domains in the display unit region located in the
(n+1)th row may be arranged in the order of the third domain, the
fourth domain, the first domain, and the second domain.
[0133] At least one of the first alignment film and the second
alignment film may be a photo alignment film. Preferably both the
first alignment film and the second alignment film are the photo
alignment film.
[0134] According to another aspect of the present invention, there
is provided a method of manufacturing the liquid crystal panel, the
method including forming the fine slits by photolithography, the
photolithography including irradiating a photosensitive resin
formed on a conductive film with light through a mask in which a
pattern corresponding to the fine slits is formed and multiple
lenses.
* * * * *