U.S. patent application number 14/192384 was filed with the patent office on 2014-06-26 for liquid crystal display device.
This patent application is currently assigned to Panasonic Liquid Crystal Display Co., Ltd.. The applicant listed for this patent is Japan Display Inc., Panasonic Liquid Crystal Display Co., Ltd.. Invention is credited to Hirotaka Imayama, Kimitoshi OUGIICHI.
Application Number | 20140176889 14/192384 |
Document ID | / |
Family ID | 45972758 |
Filed Date | 2014-06-26 |
United States Patent
Application |
20140176889 |
Kind Code |
A1 |
OUGIICHI; Kimitoshi ; et
al. |
June 26, 2014 |
Liquid Crystal Display Device
Abstract
A liquid crystal display device includes a pixel electrode, a
common electrode, and an insulating layer which is formed between
the pixel electrode and the common electrode. The pixel electrode
or the common electrode includes at least one strip shaped portion
which is extended in a first direction. A first thickness of the
insulating layer between the pixel and common electrodes at a first
portion extending from a vicinity of end of the at least one strip
shaped portion in the first direction toward the end of the at
least one strip shaped portion is thicker than a second thickness
of the insulating layer between the pixel and the common electrodes
at a second portion extending from the vicinity of end of the at
least one strip shaped portion in the first direction toward a
center of the at least one strip shaped portion.
Inventors: |
OUGIICHI; Kimitoshi;
(Mobara, JP) ; Imayama; Hirotaka; (Mobara,
JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Panasonic Liquid Crystal Display Co., Ltd.
Japan Display Inc. |
Hyogo-ken
Tokyo |
|
JP
JP |
|
|
Assignee: |
Panasonic Liquid Crystal Display
Co., Ltd.
Hyogo-ken
JP
Japan Display Inc.
Tokyo
JP
|
Family ID: |
45972758 |
Appl. No.: |
14/192384 |
Filed: |
February 27, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
13272304 |
Oct 13, 2011 |
8670095 |
|
|
14192384 |
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Current U.S.
Class: |
349/138 |
Current CPC
Class: |
G02F 2001/134372
20130101; G02F 1/133345 20130101 |
Class at
Publication: |
349/138 |
International
Class: |
G02F 1/1333 20060101
G02F001/1333 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 21, 2010 |
JP |
2010-236077 |
Claims
1. A liquid crystal display device comprising: a pixel electrode; a
common electrode generating an electric field to align liquid
crystal molecules in cooperation with the pixel electrode; and an
insulating layer which is formed between the pixel electrode and
the common electrode; wherein one of the pixel electrode and the
common electrode includes at least one strip shaped portion formed
therein which is extended in a first direction; and wherein a first
thickness of the insulating layer between the pixel electrode and
the common electrode at a first portion of the insulating layer
extending from a vicinity of end of the at least one strip shaped
portion in the first direction toward the end of the at least one
strip shaped portion is thicker than a second thickness of the
insulating layer between the pixel electrode and the common
electrode at a second portion of the insulating layer extending
from the vicinity of end of the at least one strip shaped portion
in the first direction toward a center of the at least one strip
shaped portion.
2. The liquid crystal display device according to claim 1, wherein
one of the pixel electrode and the common electrode includes a
plurality of strip shaped portions which have the at least one
strip shaped portion and are extended in the first direction.
3. The liquid crystal display device according to claim 1, wherein
a difference between the first thickness and the second thickness
of the insulating layer is formed by a first lamination number of
the insulating layer at the first portion being larger than a
second lamination number of the insulating layer at the second
portion.
4. The liquid crystal display device according to claim 1, wherein
the first portion is a domain generating region.
5. A liquid crystal display device comprising: a pixel electrode; a
common electrode generating an electric field to align liquid
crystal molecules in cooperation with the pixel electrode; and an
insulating layer which is formed between the pixel electrode and
the common electrode; wherein one of the pixel electrode and the
common electrode includes at least one strip shaped portion,
wherein the at least one strip shaped portion includes a first
extended portion which is extended in a first direction, a second
extended portion which is extended in a second direction differing
from the first direction, and an inflected portion which is
arranged between the first extended portion and the second extended
portion; and wherein a first thickness of the insulating layer
between the pixel electrode and the common electrode at the first
extended portion is thinner than a second thickness of the
insulating layer between the pixel electrode and the common
electrode at the inflected portion.
6. The liquid crystal display device according to claim 5, wherein
one of the pixel electrode and the common electrode includes a
plurality of strip shaped portions which have the at least one
strip shaped portion, each of the plurality of strip shaped
portions having the first extended portion, the second extended
portion, and the inflected portion.
7. The liquid crystal display device according to claim 5, wherein
a difference between the first thickness and the second thickness
of the insulating layer is formed by a first lamination number of
the insulating layer at the first extended portion being smaller
than a second lamination number of the insulating layer at the
inflected portion.
8. The liquid crystal display device according to claim 5, wherein
the inflected portion is a domain generating region.
9. The liquid crystal display device according to claim 5, wherein
a third thickness of the insulating layer between the pixel
electrode and the common electrode at the second extended portion
is thinner than the second thickness of the insulating layer.
10. A liquid crystal display device comprising a pixel electrode; a
common electrode generating an electric field to align liquid
crystal molecules in cooperation with the pixel electrode; and an
insulating layer which is stacked between the pixel electrode and
the common electrode; wherein one of the pixel electrode and the
common electrode includes at least one strip shaped portion,
wherein the at least one strip shaped portion includes a first
extended portion which is extended in a first direction, a second
extended portion which is extended in a second direction differing
from the first direction, and an inflected portion which is
arranged between the first extended portion and the second extended
portion; wherein a first thickness of the insulating layer between
the pixel electrode and the common electrode at the first extended
portion is thinner than a second thickness of the insulating layer
between the pixel electrode and the common electrode at the
inflected portion; and wherein a third thickness of the insulating
layer between the pixel electrode and the common electrode at a
first portion of the first extended portion from a vicinity of end
of the at least one strip shaped portion in the first direction
toward the end of the at least one strip shaped portion is thicker
than the first thickness of the insulating layer between the pixel
electrode and the common electrode at a second portion of the first
extended portion from the vicinity of end of the at least one strip
shaped portion in the first direction toward a center of the at
least one strip shaped portion.
11. The liquid crystal display device according to claim 10,
wherein one of the pixel electrode and the common electrode
includes a plurality of strip shaped portions which have the at
least one strip shaped portion, each of the plurality of strip
shaped portions having the first extended portion, the second
extended portion, and the inflected portion.
12. The liquid crystal display device according to claim 10,
wherein a difference between the first thickness and the second
thickness of the insulating layer is formed by a first lamination
number of the insulating layer at the first extended portion being
smaller than a second lamination number of the insulating layer at
the inflected portion, and a difference between the first thickness
and the third thickness of the insulating layer is formed by the
first lamination number of the insulating layer at the second
portion of the first extended portion being smaller than a third
lamination number of the insulating layer at the first portion of
the first extended portion.
13. The liquid crystal display device according to claim 10,
wherein each of the inflected portion and the first portion of the
first extended portion is a domain generating region.
14. The liquid crystal display device according to claim 10,
wherein a fourth thickness of the insulating layer between the
pixel electrode and the common electrode at the second extended
portion is thinner than the second thickness of the insulating
layer.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is a continuation of U.S. application Ser.
No. 13/272,304, filed Oct. 13, 2011, the contents of which are
incorporated herein by reference.
[0002] The present application claims priority from Japanese
application JP 2010-236077 filed on Oct. 21, 2010, the content of
which is hereby incorporated by reference into this
application.
BACKGROUND OF THE INVENTION
[0003] 1. Field of the Invention
[0004] The present invention relates to a liquid crystal display
device in which liquid crystal molecules are aligned by an electric
field generated by two electrodes stacked via an insulating
layer.
[0005] 2. Description of the Related Art
[0006] Conventionally, liquid crystal display devices are
classified into ones of a vertical electric field system and ones
of a horizontal electric field system. A liquid crystal display
device of the horizontal electric field system may obtain wider
viewing angle characteristics compared with those of a liquid
crystal display device of the vertical electric field system. Among
liquid crystal display devices of the horizontal electric field
system, ones in which a pixel electrode and a common electrode are
stacked via an insulating layer, one of the electrodes having slits
formed therein and the other of the electrodes being in the shape
of an even plane without an opening, are used when high
transmittance is required. This is because an arc-like electric
flux is distributed to the vicinity of the center of the electrode
having the slits formed therein so as to connect the pixel
electrode and the common electrode which are in different
layers.
[0007] By the way, examples of the electrode having slits formed
therein include a comb electrode in which one ends of the slits are
closed while the other ends are open, and an electrode in which
both the ends of the slits are closed. Further, in a multi-domain
liquid crystal display device, such slits in the electrode are
inflected. When an electric field is generated by an electrode
having slits formed therein and an electrode in the shape of an
even plane without an opening, an electric field in the vicinity of
ends in a longitudinal direction of the slits or in the vicinity of
inflected portions of the slits is distributed in such a way that
control of the alignment of the liquid crystal molecules is
difficult. Therefore, a region in which the alignment of the liquid
crystal molecules cannot be controlled (hereinafter, referred to as
domain) is generated in the vicinity of the ends in the
longitudinal direction of the slits or in the vicinity of the
inflected portions of the slits. The domain is responsible for
lowering the transmittance in the liquid crystal display device.
Accordingly, as disclosed in, for example, Japanese Patent
Application Laid-open No. 2008-276172, a liquid crystal display
device which reduces such a domain has been proposed.
SUMMARY OF THE INVENTION
[0008] In the liquid crystal display device disclosed in Japanese
Patent Application Laid-open No. 2008-276172, the number of ends of
slits is reduced by providing the slits so as to extend
continuously over a plurality of pixels. In other words, in the
liquid crystal display device, the domain is reduced by reducing
the number of ends of slits which are responsible for generation of
the domain.
[0009] However, in the liquid crystal display device disclosed in
Japanese Patent Application Laid-open No. 2008-276172, not all the
ends of slits are eliminated, and thus, the problem that a domain
generated in the vicinity of ends of slits lowers the transmittance
is not solved.
[0010] The present invention has been made in view of the above,
and an object of the present invention is to provide a liquid
crystal display device which improves the transmittance.
[0011] In order to solve the above-mentioned problem and to achieve
the object, according to a first aspect of the present invention,
there is provided a liquid crystal display device, including a
pixel electrode; and a common electrode generating an electric
field to align liquid crystal molecules in cooperation with the
pixel electrode; and an insulating layer which is stacked between
the pixel electrode and the common electrode; wherein one of the
pixel electrode and the common electrode included slits formed
therein, and the insulating layer is formed so as to increase in
thickness from a vicinity of ends in a longitudinal direction of
the slits toward the ends.
[0012] Further, in the liquid crystal display device according to
the first aspect of the present invention, the insulating layer may
be formed so as to gradually increase in thickness from the
vicinity of the ends in the longitudinal direction of the slits
toward the ends.
[0013] Further, in the liquid crystal display device according to
the first aspect of the present invention, the insulating layer may
be processed to be inclined in advance so as to increase in
thickness from the vicinity of the ends in the longitudinal
direction of the slits toward the ends.
[0014] Further, in the liquid crystal display device according to
the first aspect of the present invention, the vicinity of the ends
in the longitudinal direction of the slits may be a domain
generating region.
[0015] Further, in order to solve the above-mentioned problem and
to achieve the object, according to a second aspect of the present
invention, there is provided a liquid crystal display device,
including a pixel electrode; a common electrode generating an
electric field to align liquid crystal molecules in cooperation
with the pixel electrode; and an insulating layer which is stacked
between the pixel electrode and the common electrode; wherein one
of the pixel electrode and the common electrode includes slits
formed therein, and the slits are inflected, and the insulating
layer is formed so as to increase in thickness from a vicinity of
inflected portions of the slits toward the inflected portions.
[0016] Further, in the liquid crystal display device according to
the second aspect of the present invention, the insulating layer
may be formed so as to gradually increase in thickness from the
vicinity of the inflected portions of the slits toward the
inflected portions.
[0017] Further, in the liquid crystal display device according to
the second aspect of the present invention, the insulating layer
may be processed to be inclined in advance so as to increase in
thickness from the vicinity of the inflected portions of the slits
toward the inflected portions.
[0018] Further, in the liquid crystal display device according to
the second aspect of the present invention, the vicinity of the
inflected portions may be a domain generating region.
[0019] Further, in order to solve the above-mentioned problem and
to achieve the object, according to a third aspect of the present
invention, there is provided a liquid crystal display device,
including a pixel electrode; a common electrode generating an
electric field to align liquid crystal molecules in cooperation
with the pixel electrode; and an insulating layer which is stacked
between the pixel electrode and the common electrode; wherein one
of the pixel electrode and the common electrode includes slits
formed therein the slits are inflected, and the insulating layer is
formed so as to increase in thickness from a vicinity of ends in a
longitudinal direction of the slits toward the ends and is formed
so as to increase in thickness from a vicinity of inflected
portions of the slits toward the inflected portions.
[0020] Further, in the liquid crystal display device according to
the third aspect of the present invention, the insulating layer may
be formed so as to gradually increase in thickness from the
vicinity of the ends in the longitudinal direction of the slits
toward the ends and so as to gradually increase in thickness from
the vicinity of the inflected portions of the slits toward the
inflected portions.
[0021] Further, in the liquid crystal display device according to
the third aspect of the present invention, the insulating layer may
be processed to be inclined in advance so as to increase in
thickness from the vicinity of the ends in the longitudinal
direction of the slits toward the ends and so as to increase in
thickness from the vicinity of the inflected portions of the slits
toward the inflected portions.
[0022] Further, in the liquid crystal display device according to
the third aspect of the present invention, the vicinity of the ends
in the longitudinal direction of the slits and the vicinity of the
inflected portions may be domain generating regions.
[0023] Further, in the liquid crystal display device according to
the present invention, the one of the pixel electrode and the
common electrode including the slits formed therein may be a comb
electrode, and one of the ends in the longitudinal direction of the
slits may be open while another end is closed.
[0024] Further, in the liquid crystal display device according to
the present invention, the ends in the longitudinal direction of
the slits may be closed.
[0025] In the liquid crystal display device according to the
present invention in which the pixel electrode and the common
electrode are stacked via the insulating layer, the slits are
formed in one of the pixel electrode and the common electrode, and
the liquid crystal molecules are aligned by an electric field
generated by the pixel electrode and the common electrode, the
insulating layer is formed so as to increase in thickness from the
vicinity of the ends in the longitudinal direction of the slits
toward the ends, to thereby lower the intensity of the electric
field in the vicinity of the ends in the longitudinal direction of
the slits. Because of the lowered intensity of the electric field,
the liquid crystal molecules are normally aligned around the ends
in the longitudinal direction of the slits and thus suppress
enlargement of a domain which is generated by the electric field in
the vicinity of the ends in the longitudinal direction of the
slits. Therefore, the domain reduces, and, as a consequence, the
transmittance may be improved.
[0026] Further, in the liquid crystal display device according to
the present invention in which the pixel electrode and the common
electrode are stacked via the insulating layer, the slits are
formed in one of the pixel electrode and the common electrode, and
the liquid crystal molecules are aligned by an electric field
generated by the pixel electrode and the common electrode, the
slits are formed so as to be inflected, and the insulating layer is
formed so as to increase in thickness from the vicinity of the
inflected portions of the slits toward the inflected portions, to
thereby lower the intensity of the electric field in the vicinity
of the inflected portions of the slits. Because of the lowered
intensity of the electric field, the liquid crystal molecules are
normally aligned around the inflected portions of the slits and
thus suppress enlargement of a domain which is generated by the
electric field in the vicinity of the inflected portions of the
slits. Therefore, the domain reduces, and, as a consequence, the
transmittance may be improved.
[0027] Further, in the liquid crystal display device according to
the present invention in which the pixel electrode and the common
electrode are stacked via the insulating layer, the slits are
formed in one of the pixel electrode and the common electrode, and
the liquid crystal molecules are aligned by an electric field
generated by the pixel electrode and the common electrode, the
slits are formed so as to be inflected, the insulating layer is
formed so as to increase in thickness from the ends in the
longitudinal direction of the slits toward the ends, and the
insulating layer is formed so as to increase in thickness from the
vicinity of the inflected portions of the slits toward the
inflected portions, to thereby lower the intensity of the electric
field in the vicinity of the ends in the longitudinal direction of
the slits and in the vicinity of the inflected portions. Because of
the lowered intensity of the electric field, the liquid crystal
molecules are normally aligned around the ends in the longitudinal
direction of the slits and around the inflected portions and thus
suppress enlargement of a domain which is generated by the electric
field in the vicinity of the ends in the longitudinal direction of
the slits and in the vicinity of the inflected portions. Therefore,
the domain reduces, and, as a consequence, the transmittance may be
improved.
BRIEF DESCRIPTION OF THE DRAWINGS
[0028] In the accompanying drawings:
[0029] FIG. 1 is a schematic view illustrating a structure of a
liquid crystal display device according to a first embodiment of
the present invention;
[0030] FIG. 2 is a detailed explanatory diagram of a structure of a
liquid crystal display panel illustrated in FIG. 1;
[0031] FIG. 3 is a cross-sectional view of the liquid crystal
display panel taken along the line A1-A2 of FIG. 2;
[0032] FIG. 4 is a detailed explanatory diagram of a structure of a
liquid crystal display panel of a liquid crystal display device
according to a second embodiment of the present invention;
[0033] FIG. 5 is a cross-sectional view of the liquid crystal
display panel taken along the line B1-B2-B3 of FIG. 4;
[0034] FIG. 6 is a detailed explanatory diagram of a structure of a
liquid crystal display panel of a liquid crystal display device
according to a third embodiment of the present invention;
[0035] FIG. 7 is a cross-sectional view of the liquid crystal
display panel taken along the line C1-C2-C3 of FIG. 6;
[0036] FIG. 8 is a detailed explanatory diagram of a structure of a
liquid crystal display panel of a liquid crystal display device
according to a fourth embodiment of the present invention; and
[0037] FIG. 9 is a cross-sectional view of the liquid crystal
display panel taken along the line D1-D2-D3 of FIG. 8.
DETAILED DESCRIPTION OF THE INVENTION
[0038] Liquid crystal display devices according to preferred
embodiments of the present invention are described in detail in the
following with reference to the attached drawings.
First Embodiment
[0039] FIG. 1 is a schematic view illustrating a structure of a
liquid crystal display device 100 according to a first embodiment
of the present invention. FIG. 2 is a detailed explanatory diagram
of a structure of a liquid crystal display panel 10 illustrated in
FIG. 1. In FIG. 2, the part of a liquid crystal display panel 10 is
enlarged to explain the structure of pixels. FIG. 3 is a
cross-sectional view of the liquid crystal display panel 10 taken
along the line A1-A2 of FIG. 2. The liquid crystal display device
100 is of the horizontal electric field system, and includes the
liquid crystal display panel 10, a data driver 2, a scanning driver
3, a backlight unit 4, and a control unit 5.
[0040] As illustrated in FIG. 1, the liquid crystal display panel
10 includes a plurality of video signal lines DL (DL.sub.1, . . . ,
DL.sub.n, where n is a natural number) which extend in a Y
direction and a plurality of scanning signal lines GL (GL.sub.1, .
. . , GL.sub.m, where m is a natural number) which extend in an X
direction. Further, in the liquid crystal display panel 10, the
plurality of scanning signal lines GL are formed so as to be in
parallel to one another, and each of the plurality of video signal
lines DL is formed so as to cross the scanning signal lines GL. A
pixel D is formed in a region surrounded by those video signal
lines DL and scanning signal lines GL.
[0041] As illustrated in FIG. 3, a liquid crystal material 40
containing liquid crystal molecules is sealed between a TFT
substrate 20 and a counter substrate 30 in the liquid crystal
display panel 10. The TFT substrate 20 is a substrate including an
insulating substrate such as a glass substrate, and the scanning
signal lines GL, the video signal lines DL, thin film transistors
TFTs, a common electrode CT, and pixel electrodes Px provided
thereon. More specifically, the TFT substrate 20 has the scanning
signal lines GL provided on an insulating substrate SUB1 such as a
glass substrate. The scanning signal lines GL are formed by, for
example, etching a film of a conductor such as aluminum.
[0042] The video signal line DL (source electrode SD1) and a drain
electrode SD2 of the thin film transistor TFT are provided above
the scanning signal line GL via a first insulating layer PAS1.
[0043] The common electrode CT is provided above the video signal
line DL and the like via a second insulating layer PAS2. The common
electrode CT is formed by etching a film of a conductor having high
light transmittance such as ITO, and is formed in the shape of an
even plane without an opening in a region which overlaps the pixel
electrode Px in plan view. The pixel electrode Px is provided above
the common electrode CT via a third insulating layer PAS3.
[0044] The pixel electrode Px is formed by etching a film of a
conductor having high light transmittance such as ITO. The pixel
electrode Px is connected to the drain electrode SD2 via a through
hole TH. The pixel electrode Px has a plurality of slits SL formed
in the region overlapping the common electrode CT in plan view, the
slits SL having the long sides in a direction in which the video
signal lines DL extend. The pixel electrode Px is a comb electrode,
and one ends of the slits SL are open while the other ends of the
slits SL are closed.
[0045] As illustrated in FIG. 2, the pixel electrode Px has a
plurality of strip-like portions 11 formed in stripes and a joining
portion 12 for joining one ends of the plurality of strip-like
portions 11 together. The joining portion 12 is connected to the
drain electrode SD2. The slits SL of the pixel electrode Px are
formed by the strip-like portions 11 and the joining portion
12.
[0046] The slits SL each have a closed end 13a and an open end 13b.
The closed end 13a is an end closed by the joining portion 12 of
the ends in the longitudinal direction of the slit SL. The
distribution of an electric field in the vicinity of the closed
ends 13a is affected not only by the strip-like portions 11 but
also by the joining portion 12. Specifically, the vicinity of the
closed ends 13a is a domain generating region. The open end 13b is
an open end of the ends in the longitudinal direction of the slit
SL. The distribution of an electric field in the vicinity of the
open ends 13b is affected by tip portions of the strip-like
portions 11. Specifically, the vicinity of the open ends 13b is a
domain generating region.
[0047] As illustrated in FIG. 3, in the counter substrate 30, a
light shielding film BM called a black matrix and a color filter CF
are provided on a surface of an insulating substrate SUB2 such as a
glass substrate. The light shielding film BM is formed by, for
example, etching a conductive film or an insulating film having a
light transmittance of almost zero to form a lattice-like pattern
for separating the respective pixels D from one another. The color
filter CF is formed by, for example, etching or exposing to light
and developing an insulating film and periodically arranging a
filter for displaying red (R), a filter for displaying green (G),
and a filter for displaying blue (B) in an aperture region of the
light shielding film. Further, an alignment film ORI2 is provided
above the light shielding film BM and the color filter CF via, for
example, an overcoating layer OC.
[0048] The data driver 2 generates video signals (gradation
voltages) to be input to the plurality of video signal lines DL,
respectively.
[0049] The scanning driver 3 sequentially inputs scanning signals
to the plurality of scanning signal lines GL. The data driver 2 and
the scanning driver 3 are electrically connected to the liquid
crystal display panel 10 via a flexible board or the like (not
shown) connected to an outer peripheral portion of the liquid
crystal display panel 10.
[0050] The backlight unit 4 is materialized by a light-emitting
diode or the like, and irradiates light from a back surface side of
the liquid crystal display panel 10.
[0051] The control unit 5 is materialized by a CPU or the like, and
is electrically connected to respective portions of the liquid
crystal display device 100 including the data driver 2, the
scanning driver 3, and the backlight unit 4, for controlling the
overall operation of the liquid crystal display device 100. The
control unit 5 includes a memory or the like (not shown) for
temporarily holding video data which is input from an external
system.
[0052] Here, the third insulating layer PAS3 is specifically
described. As illustrated in FIG. 3, the third insulating layer
PAS3 has a first inclination layer PAS31 and a second inclination
layer PAS32.
[0053] The first inclination layer PAS31 is an insulating layer
formed on the common electrode CT. The first inclination layer
PAS31 has an inclined portion TP. The inclined portion TP is a
portion of the first inclination layer PAS31 which is processed so
as to form an inclined surface. The first inclination layer PAS31
starts its inclination at a bottom end TPb of the inclined portion
TP and ends its inclination at a top end TPt. The inclined portion
TP is processed in advance before the second inclination layer
PAS32 is stacked thereon.
[0054] The inclined portion TP is inclined at a predetermined
inclination angle with respect to a surface of the common electrode
CT. For example, the inclined portion
[0055] TP is inclined at an inclination angle of 10 degrees with
respect to the surface of the common electrode CT. Note that, the
inclination angle of the inclined portion TP is not limited to 10
degrees. In other words, the inclination angle may be appropriately
set depending on the domain generating region. The first
inclination layer PAS31 is processed to be inclined so as to
gradually increase in thickness from the vicinity of the closed
ends 13a toward the closed ends 13a and so as to gradually increase
in thickness from the vicinity of the open ends 13b toward the open
ends 13b.
[0056] The second inclination layer PAS32 is an insulating layer
formed on the first inclination layer PAS31 after the first
inclination layer PAS31 is processed to be inclined as described
above.
[0057] The third insulating layer PAS3 is formed by the first
inclination layer PAS31 which is processed to be inclined and the
second inclination layer PAS32 which is stacked on the first
inclination layer PAS31, so as to gradually increase in thickness
from the vicinity of the closed ends 13a toward the closed ends 13a
and so as to gradually increase in thickness from the vicinity of
the open ends 13b toward the open ends 13b. Therefore, in the
vicinity of the closed ends 13a and in the vicinity of the open
ends 13b, that is, in the domain generating regions, the intensity
of the electric field generated by the pixel electrode Px and the
common electrode CT becomes lower. Further, the intensity of the
electric field changes so as to be gradually lowered toward the
closed ends 13a and toward the open ends 13b, and thus, control of
the alignment of the liquid crystal molecules is not adversely
affected.
[0058] Note that, it is desired that the third insulating layer
PAS3 gradually increase in thickness, but it is enough that the
control of the alignment of the liquid crystal molecules is not
adversely affected. For example, it is enough that the third
insulating layer PAS3 increases in thickness from the vicinity of
the closed ends 13a toward the closed ends 13a and from the
vicinity of the open ends 13b toward the open ends 13b,
respectively.
[0059] In the first embodiment of the present invention, the third
insulating layer PAS3 is formed so as to gradually increase in
thickness from the vicinity of the closed ends 13a toward the
closed ends 13a and is formed so as to gradually increase in
thickness from the vicinity of the open ends 13b toward the open
ends 13b, to thereby lower the intensity of the electric field in
the vicinity of the closed ends 13a and in the vicinity of the open
ends 13b. Because of the lowered intensity of the electric field,
liquid crystal molecules are normally aligned in the vicinity of
the closed ends 13a and in the vicinity of the open ends 13b and
thus suppress enlargement of a domain which is generated by the
electric field in the vicinity of the closed ends 13a and in the
vicinity of the open ends 13b. Therefore, the domain reduces, and,
as a consequence, the transmittance may be improved.
[0060] Further, in the first embodiment of the present invention,
the liquid crystal molecules which are normally aligned in the
vicinity of the closed ends 13a and in the vicinity of the open
ends 13b due to the lowered intensity of the electric field in the
vicinity of the closed ends 13a and in the vicinity of the open
ends 13b suppress the enlargement of the domain which is generated
by the electric field in the vicinity of the closed ends 13a and in
the vicinity of the open ends 13b, and thus, even when the screen
of the liquid crystal display panel 10 is pressed, the enlargement
of the domain may be suppressed and time necessary for the screen
to return to its original state may be shortened.
Second Embodiment
[0061] Next, a second embodiment of the present invention is
described with reference to FIG. 4 and FIG. 5. FIG. 4 is a detailed
explanatory diagram of a structure of a liquid crystal display
panel 60 of a liquid crystal display device 200 according to the
second embodiment of the present invention. FIG. 5 is a
cross-sectional view of the liquid crystal display panel 60 taken
along the line B1-B2-B3 of FIG. 4. In the first embodiment of the
present invention, the slits SL are in the shape of straight lines,
but, in the second embodiment, the slits SL each have a inflected
portion 13c. The third insulating layer PAS3 is formed so as to
gradually increase in thickness from the vicinity of the inflected
portions 13c toward the inflected portions 13c. Other structures in
the second embodiment are the same as those in the first
embodiment, and like reference symbols are used to designate like
structural elements.
[0062] As illustrated in FIG. 4, a pixel electrode Px has a
plurality of strip-like portions 11 formed in stripes and a joining
portion 12 for joining one ends of the plurality of strip-like
portions 11 together. The strip-like portions 11 are inflected so
as to be V-shaped. In the pixel electrode Px, the slits SL which
are inflected to be V-shaped are formed by the strip-like portions
11 and the joining portion 12.
[0063] The inflected portions 13c correspond to the inflected shape
of the pixel electrode Px. Such V-shaped slits SL are widely
employed in multi-domain liquid crystal display devices. The
distribution of an electric field in the vicinity of the inflected
portions 13c is affected by the inflected shape. Specifically, the
vicinity of the inflected portions 13c is a domain generating
region. As illustrated in FIG. 5, an alignment film ORI1 is
provided on the pixel electrode Px. Note that, the shape of the
slits SL is not limited to being inflected so as to be V-shaped. It
is enough that the slits SL have inflected portions which
accommodate a multi-domain liquid crystal display device.
[0064] Here, the third insulating layer PAS3 is specifically
described. As illustrated in FIG. 5, the third insulating layer
PAS3 has a first inclination layer PAS33 and a second inclination
layer PAS34.
[0065] The first inclination layer PAS33 is an insulating layer
formed on the common electrode CT. The first inclination layer
PAS33 is processed to be inclined so as to gradually increase in
thickness from the vicinity of the inflected portions 13c of the
slits SL toward the inflected portions 13c.
[0066] The second inclination layer PAS34 is an insulating layer
formed on the first inclination layer PAS33 after the first
inclination layer PAS33 is processed to be inclined as described
above.
[0067] The third insulating layer PAS3 is formed by the first
inclination layer PAS33 which is processed to be inclined and the
second inclination layer PAS34 which is stacked on the first
inclination layer PAS33, so as to gradually increase in thickness
from the vicinity of the inflected portions 13c of the slits SL
toward the inflected portions 13c. Therefore, in the vicinity of
the inflected portions 13c, that is, in the domain generating
region, the intensity of the electric field generated by the pixel
electrode Px and the common electrode CT becomes lower. Further,
the intensity of the electric field changes so as to be gradually
lowered toward the inflected portions 13c, and thus, control of the
alignment of the liquid crystal molecules is not adversely
affected.
[0068] In the second embodiment of the present invention, the third
insulating layer PAS3 is formed so as to gradually increase in
thickness from the vicinity of the inflected portions 13c toward
the inflected portions 13c, to thereby lower the intensity of the
electric field in the vicinity of the inflected portions 13c.
Because of the lowered intensity of the electric field, liquid
crystal molecules are normally aligned in the vicinity of the
inflected portions 13c and thus suppress enlargement of a domain
which is generated by the electric field in the vicinity of the
inflected portions 13c. Therefore, the domain reduces, and, as a
consequence, the transmittance may be improved.
[0069] Further, in the second embodiment of the present invention,
the pixel electrode Px is inflected, and thus, restrictions on the
viewing angle may be eased.
Third Embodiment
[0070] Next, a third embodiment of the present invention is
described with reference to FIG. 6 and FIG. 7. FIG. 6 is a detailed
explanatory diagram of a structure of a liquid crystal display
panel 70 of a liquid crystal display device 300 according to the
third embodiment of the present invention. FIG. 7 is a
cross-sectional view of the liquid crystal display panel 70 taken
along the line C1-C2-C3 of FIG. 6. In the second embodiment of the
present invention, the third insulating layer PAS3 is formed so as
to gradually increase in thickness from the vicinity of the
inflected portions 13c toward the inflected portions 13c. In the
third embodiment, further, the third insulating layer PAS3 is
formed so as to gradually increase in thickness from the vicinity
of the closed ends 13a toward the closed ends 13a and is formed so
as to gradually increase in thickness from the vicinity of the open
ends 13b toward the open ends 13b. Other structures in the third
embodiment are the same as those in the second embodiment, and like
reference symbols are used to designate like structural
elements.
[0071] Here, the third insulating layer PAS3 is specifically
described. As illustrated in FIG, 7, the third insulating layer
PAS3 has a first inclination layer PAS35 and a second inclination
layer PAS36.
[0072] The first inclination layer PAS35 is processed to be
inclined so as to gradually increase in thickness from the vicinity
of the closed ends 13a toward the closed ends 13a and so as to
gradually increase in thickness from the vicinity of the open ends
13b toward the open ends 13b. Further, the first inclination layer
PAS35 is processed to be inclined so as to gradually increase in
thickness from the vicinity of the inflected portions 13c toward
the inflected portions 13c.
[0073] The second inclination layer PAS36 is an insulating layer
formed on the first inclination layer PAS35 after the first
inclination layer PAS35 is processed to be inclined as described
above.
[0074] The third insulating layer PAS3 is formed by the first
inclination layer PAS35 which is processed to be inclined and the
second inclination layer PAS36 which is stacked on the first
inclination layer PAS35, so as to gradually increase in thickness
from the vicinity of the closed ends 13a toward the closed ends 13a
and so as to gradually increase in thickness from the vicinity of
the open ends 13b toward the open ends 13b. Further, the third
insulating layer PAS3 is formed so as to gradually increase in
thickness from the vicinity of the inflected portions 13c toward
the inflected portions 13c. Therefore, in the vicinity of the
closed ends 13a, in the vicinity of the open ends 13b, and in the
vicinity of the inflected portions 13c, that is, in the domain
generating regions, the intensity of the electric field generated
by the pixel electrode Px and the common electrode CT becomes
lower. Further, the intensity of the electric field changes so as
to be gradually lowered toward the closed ends 13a, toward the open
ends 13b, and toward the inflected portions 13c, and thus, control
of the alignment of the liquid crystal molecules is not adversely
affected.
[0075] In the third embodiment of the present invention, the third
insulating layer PAS3 is formed so as to gradually increase in
thickness from the vicinity of the inflected portions 13c toward
the inflected portions 13c, to thereby obtain the same effect as
that in the second embodiment, and is formed so as to gradually
increase in thickness from the vicinity of the closed ends 13a
toward the closed ends 13a and so as to gradually increase in
thickness from the vicinity of the open ends 13b toward the open
ends 13b, to thereby lower the intensity of the electric field in
the vicinity of the closed ends 13a and in the vicinity of the open
ends 13b. Because of the lowered intensity of the electric field,
liquid crystal molecules are normally aligned in the vicinity of
the closed ends 13a and in the vicinity of the open ends 13b and
thus suppress enlargement of a domain which is generated by the
electric field in the vicinity of the closed ends 13a and in the
vicinity of the open ends 13b. Therefore, the domain reduces, and,
as a consequence, the transmittance may be improved.
Fourth Embodiment
[0076] Next, a fourth embodiment of the present invention is
described with reference to FIG. 8 and FIG. 9. FIG. 8 is a detailed
explanatory diagram of a structure of a liquid crystal display
panel 80 of a liquid crystal display device 400 according to the
fourth embodiment of the present invention. FIG. 9 is a
cross-sectional view of the liquid crystal display panel 80 taken
along the line D1-D2-D3 of FIG. 8. In the third embodiment, the
pixel electrode Px of the liquid crystal display panel 70 is a comb
electrode in which one ends of both ends in the longitudinal
direction of the slits SL are open, but, in the fourth embodiment,
the pixel electrode Px of the liquid crystal display panel 80 is an
electrode in which both ends in the longitudinal direction of the
slits SL are closed.
[0077] As illustrated in FIG. 8, the pixel electrode Px has a
plurality of strip-like portions 14 formed in stripes and joining
portions 15 each for joining ends of the plurality of strip-like
portions 14 together on one side. The slits SL of the pixel
electrode Px are formed by the strip-like portions 14 and the
joining portions 15.
[0078] The slits SL each have closed ends 70a and 70b and a
inflected portion 70c. The closed ends 70a and 70b are ends closed
by the joining portions 15. The distribution of an electric field
in the vicinity of the closed ends 70a and 70b is affected not only
by the strip-like portions 14 but also by the joining portions 15.
Specifically, the vicinities of the closed ends 70a and 70b are
domain generating regions. The inflected portions 70c correspond to
the inflected shape of the pixel electrode Px. The distribution of
an electric field in the vicinity of the inflected portions 70c is
affected by the inflected shape. Specifically, the vicinity of the
inflected portions 70c is a domain generating region. Further, as
illustrated in FIG. 9, the third insulating layer PAS3 has a first
inclination layer PAS37 and a second inclination layer PAS38. Other
structures in the fourth embodiment are the same as those in the
third embodiment, and like reference symbols are used to designate
like structural elements.
[0079] As illustrated in FIG. 9, the first inclination layer PAS37
is processed to be inclined so as to gradually increase in
thickness from the vicinity of the closed ends 70a toward the
closed ends 70a and so as to gradually increase in thickness from
the vicinity of the closed ends 70b toward the closed ends 70b.
Further, the third insulating layer PAS3 is processed to be
inclined so as to gradually increase in thickness from the vicinity
of the inflected portions 70c toward the inflected portions 70c.
The second inclination layer PAS38 is an insulating layer formed on
the first inclination layer PAS37 after the first inclination layer
PAS37 is processed to be inclined as described above.
[0080] The third insulating layer PAS3 is formed by the first
inclination layer PAS37 which is processed to be inclined and the
second inclination layer PAS38 which is stacked on the first
inclination layer PAS37, so as to gradually increase in thickness
from the vicinity of the closed ends 70a toward the closed ends 70a
and so as to gradually increase in thickness from the vicinity of
the closed ends 70b to the closed ends 70b. Further, the third
insulating layer PAS3 is processed to be inclined so as to
gradually increase in thickness from the vicinity of the inflected
portions 70c toward the inflected portions 70c.
[0081] In the fourth embodiment of the present invention, the
insulating layer PAS3 is formed so as to gradually increase in
thickness from the vicinity of the closed ends 70a toward the
closed ends 70a, so as to gradually increase in thickness from the
vicinity of the closed ends 70b toward the closed ends 70b, and
further so as to gradually increase in thickness from the vicinity
of the inflected portions 70c toward the inflected portions 70c, to
thereby lower the intensity of the electric field in the vicinities
of the closed ends 70a and 70b and in the vicinity of the inflected
portions 70c. Because of the lowered intensity of the electric
field, liquid crystal molecules are normally aligned in the
vicinities of the closed ends 70a and 70b and in the vicinity of
the inflected portions 70c and thus suppress enlargement of a
domain which is generated by the electric field in the vicinities
of the closed ends 70a and 70b and in the vicinity of the inflected
portions 70c. Therefore, even when the pixel electrode Px is a
pixel electrode in which both ends of the slits SL are closed, the
transmittance may be improved.
[0082] Note that, in the first to fourth embodiments of the present
invention, the longitudinal direction of the slits SL is the
direction in which the video signal lines DL extend, but the
present invention is not limited thereto. For example, the
longitudinal direction of the slits SL may be a direction in which
the scanning signal lines GL extend.
[0083] Further, in the first to fourth embodiments of the present
invention, the pixel electrode Px is provided above the common
electrode CT, but the present invention is not limited thereto. For
example, the arrangement may be upside down in which the pixel
electrode Px is provided below the common electrode CT.
[0084] Further, in the first to fourth embodiments of the present
invention, the pixel electrode Px has the slits SL formed therein
and the common electrode CT is in the shape of an even plane
without an opening, but the present invention is not limited
thereto. For example, the pixel electrode Px may be in the shape of
an even plane without an opening and the common electrode CT may
have the slits SL formed therein.
[0085] Further, in the first to fourth embodiments of the present
invention, the third insulating layer PAS3 is gradually increased
in thickness by processing the first inclination layer PAS31,
PAS33, PAS35, or PAS37 to be inclined in advance, but the present
invention is not limited thereto. It is enough that the third
insulating layer PAS3 gradually increases in thickness from the
vicinities of ends of the slits SL toward the ends of the slits SL
or from the vicinity of the inflected portions of the slits SL
toward the inflected portions. For example, the third insulating
layer PAS3 may have a single-layer structure and the
single-layer-structured third insulating layer PAS3 may be
processed to be inclined in advance.
[0086] Further, in the first, second, and fourth embodiments of the
present invention, the third insulating layer PAS3 is gradually
increased in thickness toward both the ends of the slits SL, but
the present invention is not limited thereto. For example, the
third insulating layer PAS3 may gradually increase in thickness
only toward one ends of the slits SL.
[0087] Further, in the fourth embodiment of the present invention,
the slits SL are inflected, but the present invention is not
limited thereto, and the slits SL may be in the shape of straight
lines.
[0088] Note that, the present invention is not limited to the first
to fourth embodiments of the present invention.
[0089] While there have been described what are at present
considered to be certain embodiments of the invention, it will be
understood that various modifications may be made thereto, and it
is intended that the appended claims cover all such modifications
as fall within the true spirit and scope of the invention.
* * * * *