5
1
DES C RIP T ION
Title of Invention:
COLOR FILTER SUBSTRATE FOR OBLIQUE
ELECTRIC FIELD LIQUID CRYSTAL DISPLAY
DEVICES, AND LIQUID CRYSTAL DISPLAY DEVICE
Technical Field
The present invention relates to a color filter
10 substrate for a liquid crystal display device, and a
liquid crystal display device equipped with the same.
Particularly, the present invention relates to a color
filter substrate which is optimal for driving of liquid
crystals by means of an oblique electric field that is
15 generated when a voltage is applied between a third
electrode, which is a transparent conductive film
including a color filter substrate, and first and
second electrodes including an array substrate side,
and a liquid crystal display device equipped with this
20 color filter substrate.
Background Art
In recent years, there has been a demand for a
further enhancement of image quality, price reduction,
and electric power saving of a thin display device such
25 as a liquid crystal display device. In regard to a
color filter for a liquid crystal display device, there
is a demand for sufficient color purity, high contrast,
flatness and the like, suited to a display with higher
image quality.
2
In regard to a liquid crystal display with high
image quality, an alignment mode of liquid crystals or
a liquid crystal driving system such as VA (Vertically
Alignment), HAN (Hybrid-Aligned Nematic), TN (Twisted
5 Nematic), OCB (Optically Compensated Bend), or CPA
(Continuous Pinwheel Alignment) has been suggested, and
thereby, a display with wide viewing angle and highspeed
response has been put to practical use.
In a liquid crystal display device of the VA mode
10 in which liquid crystal molecules are aligned in
parallel to a plane of a substrate formed of glass or
the like, and it is easy to cope with high speed
response at a high viewing angle; the HAN mode which is
effective for a wide viewing angle; or the like, higher
15 level of flatness (uniformity of a film thickness, or
reduction of surface asperities at a color filter
surface) and an electrical characteristic such as a
dielectric constant are required for a color filter.
In such a high image quality liquid crystal display,
20 due to a decrease in coloration upon viewing in an
oblique direction, a technology for making a liquid
crystal cell thickness (thickness of a liquid crystal
layer) small are considered as an important object.
Regarding such a technology, in the VA mode, a
25 development of various improved modes such as a MVA
(Multi-Domain Vertically Alignment), PVA (Patterned
Vertically Alignment), VAECB (Vertically Alignment
3
Electrically Controlled Birefringence), VAHAN (Vertical
Alignment Hybrid-Aligned Nematic) and VATN (Vertically
Alignment Twisted Nematic) is underway.
Furthermore, in a liquid crystal display device of
5 a longitudinal electric field mode in which a driving
voltage is applied in a thickness direction of liquid
crystals, such as the VA mode, higher speed response of
liquid crystals, a wider viewing angle, and a higher
transmittance have been considered as important object.
10 The MVA technology is a technology for securing a wide
viewing angle, in order to solve a problem of unstable
vertical alignment of liquid crystal molecules at the
time of an application of a voltage for driving liquid
crystals (problem that a direction in which the liquid
15 crystals that are initially aligned vertically to the
substrate surface would tilt at a time of a voltage
application, is not easily determined), by providing
plural structures for liquid crystal alignment
regulation called ribs or slits, and forming liquid
20 crystal domains between these ribs while forming
domains with plural directions of alignment at the same
time. Japanese Patent No. 2947350 discloses a
technology of forming liquid crystal domains by using
first and second alignment regulating structures
25 (ribs) .
When the liquid crystals exhibit negative
dielectric constant anisotropy, specifically, liquid
4
crystal molecules located between two plastic ribs that
are formed above a color filter or the like, tend to
tilt in a direction, for example, perpendicular to
these ribs in a planar view and to align in parallel to
5 a substrate plane, when a driving voltage is applied.
However, the liquid crystal molecules at a center of
these two ribs do not have the direction of tilt
definitively determined despite the voltage
application, and may adopt a splay alignment or a bend
10 alignment. Such an alignment disorder of liquid
crystals has led to a rough texture in the liquid
crystal display or display unevenness. Furthermore, in
the case of the MVA mode, in addition to the problems
described above, it has been difficult to finely
15 control the amount of tilt of the liquid crystal
molecules by means of the driving voltage, and there
has been difficulty in achieving a half-tone display.
In order to solve such problems, a technology of
using a transparent conductive film (a transparent
20 electrode, a display electrode, or a third electrode)
of the color filter substrate side and first and second
electrodes of the array substrate side, and controlling
liquid crystals in a vertical alignment by means of an
oblique electric field that is generated when a voltage
25 is applied to these electrodes, has been disclosed in
Japanese Patent No. 2859093 and Japanese Patent
No. 4459338. In Japanese Patent No. 2859093, liquid
5
crystals exhibiting negative dielectric constant
anisotropy are used, and in Japanese Patent
No. 4459338, liquid crystals exhibiting positive
dielectric anisotropy are described.
5 The technique of controlling the liquid crystal
alignment by the oblique electric field by using first,
second and third electrodes as disclosed in Japanese
Patent No. 2859093 or Japanese Patent No. 4459338, is
very effective. The oblique electric field allows the
10 direction of tilt of the liquid crystals to be decided.
Also, it is easy to control the amount of tilt of the
liquid crystals by the oblique electric field, and a
significant effect is obtained in a half-tone display.
However, even in these technologies, a measure for
15 disclination of the liquid crystals is insufficient.
Disclination is a problem that regions with different
light transmittances occur in a pixel (a pixel is a
minimum unit of liquid crystal display, and in the
present specification, the pixel has the same meaning
20 as a rectangular pixel as indicated) due to unintended
alignment disorder or non-alignment of liquid crystals.
Japanese Patent No. 2859093 describes a liquid
crystal display device based on an electrically
controlled birefringence (ECB) mode with improved
25 screen roughness. This liquid crystal display device
described in Japanese Patent No. 2859093 is provided
with an alignment control window where there is no
6
transparent conductive film at a center of the pixel of
a counter electrode (third electrode), due to fixing of
a disclination at the center of the pixel. However,
the patent document does not disclose any remedial
5 measure for the disclination in a periphery of the
pixel. Furthermore, the fixing of the disclination at
the center of the pixel can be achieved, but tilting of
the liquid crystals at the center of a display
electrode is insufficient, and it is difficult to
10 expect a high transmittance. Furthermore, there is no
description on a technology for improving a
responsiveness of the liquid crystals, and there is no
disclosure related to a color filter technology.
In Japanese Patent No. 4459338, as more dielectric
15 layers are laminated above a transparent conductive
film (transparent electrode), an effect of the oblique
electric field is increased, which is preferable.
However, as shown in FIG. 7 of Japanese Patent
No. 4459338, there is a problem that vertically aligned
20 liquid crystals remain at the center of the pixel and
edges of the pixel even after application of a voltage,
and this lead to a decrease in the transmittance or
numerical aperture. Furthermore, in the case of using
liquid crystals which exhibit positive dielectric
25 constant anisotropy (in Japanese Patent No. 4459338,
there is no disclosure regarding liquid crystals which
exhibit negative dielectric constant anisotropy), since
7
a control of the liquid crystals at a midsection of the
pixel is insufficiently achieved, it is difficult to
increase the transmittance. Therefore, this is a
technology that is difficult to employ in a
5 transflective (semi-transmissive) type liquid crystal
display device.
Usually, a basic configuration of a liquid crystal
display device of VA mode, TN mode or the like is a
configuration in which liquid crystals are interposed
10 between a color filter substrate equipped with a common
electrode, and an array substrate equipped with plural
pixel electrodes (for example, a transparent electrode
that is electrically connected to a TFT element and is
formed in a comb-shaped pattern) that drive liquid
15 crystals. In this configuration, a driving voltage is
20
25
applied between the common electrode of the color
filter and the pixel electrodes formed for the array
substrate side, and thereby the liquid crystals are
driven. Regarding the transparent conductive film as
the pixel electrode or the common electrode on the
surface of the color filter, usually a thin film of an
electrically conductive metal oxide such as an ITO
(indium tin oxide), IZO (indium zinc oxide) or IGZO
(indium gallium zinc oxide) is used.
A configuration of a color filter in which a blue
pixel, a green pixel and a red pixel are formed above a
transparent conductive film is disclosed in FIG. 2 of
8
Jpn. Pat. Appln. KOKOKU Publication No. 5-26161.
Furthermore, a technology for forming a color filter
above a transparent electrode (transparent conductive
film), which is a technology of using plural stripe
5 electrodes and liquid crystals that exhibit positive
dielectric constant anisotropy, is described in the
foregoing Japanese Patent No. 4459338 (for example,
FIG. 7 and FIG. 9 of the relevant document) .
Furthermore, as a technology for increasing a
10
15
20
25
luminance or brightness in order to obtain a dynamic
display with a higher image quality, or for extending a
chromaticity range, a technology of adding a yellow
pixel or a white pixel in addition to the red pixel,
green pixel and blue pixel, and thereby configuring a
four-color display, is disclosed in Jpn. Pat. Appln.
KOKAI Publication No. 2010-9064, Japanese Patent
No. 4460849, and Jpn. Pat. Appln. KOKAI Publication
No. 2005-352451.
However, regarding these technologies, there is a
need to provide a separate pixel such as a yellow pixel
or a white pixel in addition to the existing red pixel,
green pixel and blue pixel, and an active element (TFT)
for driving this separate pixel and one more color
layer for forming a color filter are needed. Thus, an
increase in a cost caused by an increase in the number
of processes is unavoidable. Furthermore, in a
gradation display range in where a yellow display or a
9
white display with high brightness intensity is not
necessary, there is a problem that it is necessary to
suppress the display of the white pixel or the yellow
pixel, or to have a light turned off, and this does not
5 quite lead to an effective increase in the luminance.
Furthermore, it has been necessary to adjust a color
temperature of a backlight or pixels areas for
different colors, in order to take white balance. In
addition, in a reflection type display, there is a
10 problem that a display takes on an emphasized yellow
tinge in all cases (in order to suppress the yellow
tinge, for example, a special blue filter disclosed in
Jpn. Pat. Appln. KOKAI Publication No. 2005-352451 is
required) .
15
20
Summary of Invention
Technical Problem
It is an object of the present invention to
provide a color filter substrate for an oblique
electric field liquid crystal display device capable of
higher luminance display (hereinafter, dynamic display)
or capable of transflective display by achieving a
balance between a gradation display and an improvement
in responsiveness, and an oblique electric field liquid
crystal display device equipped with this color filter
25 substrate.
It is an object of an embodiment of the present
invention to provide a liquid crystal display substrate
10
which has reduced disclination, is bright, has
satisfactory responsiveness, and is adequate for
driving of liquid crystals by an oblique electric
field, and a liquid crystal display device equipped
5 with the substrate.
Solution to the Problems
In a first aspect of the present invention, a
color filter substrate for an oblique electric field
liquid crystal display device is provided. The color
10 filter substrate includes a transparent substrate, a
black matrix that is formed above the transparent
substrate and includes openings having a polygonal
shape in which opposite sides are parallel to each
other, a transparent conducive film that is provided
15
20
25
above the black matrix and the transparent substrate
within the openings, color pixels of plural colors each
having a polygonal shape in which opposite sides are
parallel to each other, each of the color pixels being
provided above the transparent conductive film and
including, within each of the openings, a region that
is partitioned into two regions respectively having
different transmittances, and a first transparent resin
layer that is provided so as to cover the color pixels.
In a second aspect of the present invention, a
color filter substrate for an oblique electric field
liquid crystal display device is provided. The color
filter substrate includes a transparent substrate, a
11
transparent conductive film that is formed above the
transparent substrate, a black matrix that is provided
above the transparent conductive film and includes
openings having a polygonal shape in which opposite
5 sides are parallel to each other, color pixels of
plural colors each having a polygonal shape in which
opposite sides are parallel to each other, each of the
color pixels being provided above the black matrix and
above the transparent conductive film within the
10
15
20
25
openings and comprising, within each of the openings, a
region that is partitioned into two regions
respectively having different transmittances, and a
first transparent resin layer that is provided so as to
cover the color pixels. The black matrix is formed of
a material having a higher relative permittivity than
relative permittivities of the color pixels.
In a third aspect of the present invention, a
color filter substrate for an electric field liquid
crystal display device is provided. The color filter
substrate includes a transparent substrate, a
transparent conductive film that is formed above the
transparent substrate, a black matrix that is provided
above the transparent conductive film and includes
openings having a polygonal shape in which opposite
sides are parallel to each other, and color pixels of
plural colors each having a polygonal shape in which
opposite sides are parallel to each other, each of the
12
color pixels being provided above the black matrix and
above the transparent conductive film within each of
the openings. The transparent conductive film has, at
a central area of each of the openings, a linear slit
5 that is parallel to a side in a longitudinal direction
of the opening.
In a fourth aspect of the present invention, a
color filter substrate for an electric field liquid
crystal display device is provided. The color filter
10
15
20
substrate includes a transparent substrate, a black
matrix that is formed above the transparent substrate
and includes openings having a polygonal shape in which
opposite sides are parallel to each other, a
transparent conductive film that is provided above the
black matrix and above the transparent substrate within
the openings, and color pixels of plural colors each
having a polygonal shape in which opposite sides are
parallel to each other, and the color pixels being
provided above the transparent conductive film. The
transparent conductive film has, at a central area of
each of the openings, a linear slit that is parallel to
a side in a longitudinal direction of the opening.
In a fifth aspect of the present invention, an
oblique electric field liquid crystal display device is
25 provided. The oblique electric field liquid crystal
display device includes the color filter substrate
according to anyone of the first to fourth of the
13
present invention as described above; an array
substrate disposed to face the color filter substrate,
the array substrate having elements for driving liquid
crystals arranged in a matrix form; and a liquid
5 crystal layer interposed between the color filter
substrate and the array substrate. The array substrate
includes a first electrode and a second electrode, to
which different potentials are applied in order to
drive liquid crystals, correspondingly in each of the
10 color pixels of the color filter substrate in a planar
view.
In a sixth aspect of the present invention, an
oblique electric field liquid crystal display device is
provided. The oblique electric field liquid crystal
15 display device includes: a color filter substrate
including a transparent substrate, a black matrix that
is formed above the transparent substrate and includes
openings having a polygonal shape in which opposite
sides are parallel to each other, a transparent
20 conductive film that is provided above the black matrix
and above the transparent substrate within the
openings, and color pixels of plural colors that are
formed above the transparent conductive film and each
have a polygonal shape in which opposite sides are
25 parallel to each other, with the transparent conductive
film having, at a center of each of the openings, a
linear slit that is parallel to a side in a
14
longitudinal direction of the opening; an array
substrate that is disposed to face the color filter
substrate and includes a first electrode having a combshaped
pattern that is connected to an active element
5 for driving liquid crystals, and a second electrode
having a comb-shaped pattern that is provided with an
insulating layer interposed between the first electrode
and the second electrode, and protrudes from an end of
the first electrode in a direction that becomes distant
10 from a center that bisects the opening in a planar
view; and a liquid crystal layer that is interposed
between the color filter substrate and the array
substrate.
In a seventh aspect of the present invention, an
15 oblique electric field liquid crystal display device is
provided. The oblique electric field liquid crystal
display device includes: a color filter substrate
including a transparent substrate, a transparent
conductive film formed above the transparent substrate,
20 a black matrix that is formed above the transparent
conductive film and includes openings having a
polygonal shape in which opposite sides are parallel to
each other, and color pixels of plural colors that are
formed above the black matrix and above the transparent
25 conductive film within the openings and each have a
polygonal shape in which opposite sides are parallel to
each other, with the transparent conductive film
15
having, at a center of each of the openings, a linear
slit that is parallel to a side in a longitudinal
direction of the opening; an array substrate that is
disposed to face the color filter substrate and
5 includes a first electrode having a comb-shaped pattern
that is connected to an active element for driving
liquid crystals, and a second electrode having a combshaped
pattern that is provided with an insulating
layer interposed between the first electrode and the
10 second electrode, and protrudes from an end of the
first electrode in a direction that becomes distant
from a center that bisects the opening in a planar
view; and a liquid crystal layer that is interposed
between the color filter substrate and the array
15 substrate.
In an eighth aspect of the present invention, an
oblique electric field liquid crystal display device is
provided. The oblique electric field liquid crystal
display device includes: an array substrate including a
20
25
first electrode having a comb-shaped pattern that is
connected to an active element for driving liquid
crystals, and a second electrode having a comb-shaped
pattern that is provided with an insulating layer
interposed between the first electrode and the second
electrode, and protrudes from an end of the first
electrode in a direction that becomes distant from a
center that bisects the opening in a planar view; a
16
color filter substrate that is disposed to face the
array substrate and includes a transparent substrate, a
transparent conductive film formed above the
transparent substrate, a black matrix that is formed
5 above the transparent conductive film and includes
openings having a polygonal shape in which opposite
sides are parallel to each other, color pixels of
plural colors that are formed above the black matrix
and above the transparent conductive film within the
10 openings and each have a polygonal shape in which
opposite sides are parallel to each other, a first
transparent resin layer provided so as to cover the
color pixels, and a set of linear conductors formed
from a transparent conductive film, the linear
15 conductors being disposed above the first transparent
resin layer and being disposed symmetrically with
respect to a center of the pixel and in parallel to the
comb-shaped pattern of the second electrode on an inner
side of the second electrode that is closest to a pixel
20 center in a planar view; and a liquid crystal layer
that is interposed between the array substrate and the
color substrate.
Brief Description of Drawings
FIG. 1 is a cross-sectional diagram illustrating a
25 color filter substrate according to a first embodiment
of the present invention.
FIG. 2 is a cross-sectional diagram illustrating
5
10
17
the color filter substrate according to the first
embodiment of the present invention.
FIG. 3 is a cross-sectional diagram illustrating
the color filter substrate according to the first
embodiment of the present invention.
FIG. 4 is a cross-sectional diagram illustrating
the color filter substrate according to the first
embodiment of the present invention.
FIG. 5 is a cross-sectional diagram illustrating
the color filter substrate according to the first
embodiment of the present invention.
FIG. 6 is a diagram illustrating an operation of
liquid crystals of a liquid crystal display device
according to a second embodiment of the present
15 invention.
FIG. 7 is a diagram illustrating an operation of
the liquid crystals of the liquid crystal display
device according to the second embodiment of the
present invention.
20
25
FIG. 8 is a diagram illustrating an operation of
the liquid crystals of the liquid crystal display
device according to the second embodiment of the
present invention.
FIG. 9 is a diagram illustrating an operation of
the liquid crystals of the liquid crystal display
device according to the second embodiment of the
present invention.
18
FIG. 10 is a cross-sectional diagram of a liquid
crystal display device equipped with the color filter
substrate according to the first embodiment of the
present invention.
5 FIG. 11 is a cross-sectional diagram of a liquid
crystal display device according to a third embodiment
of the present invention.
FIG. 12 is a cross-sectional diagram of a liquid
crystal display device according to a fourth embodiment
10 of the present invention.
FIG. 13 is a cross-sectional diagram of the liquid
crystal display device according to the fourth
embodiment of the present invention.
FIG. 14 is a cross-sectional diagram of the liquid
15 crystal display device according to the fourth
embodiment of the present invention.
FIG. 15 is a cross-sectional diagram of the liquid
crystal display device according to the fourth
embodiment of the present invention.
20 FIG. 16 is a cross-sectional diagram of the liquid
crystal display device according to the fourth
embodiment of the present invention.
FIG. 17 is a cross-sectional diagram of the liquid
crystal display device according to the fourth
25 embodiment of the present invention.
FIG. 18 is a cross-sectional diagram of a liquid
crystal display device according to a fifth embodiment
5
20
19
of the present invention.
FIG. 19 is a cross-sectional diagram of the liquid
crystal display device according to the fifth
embodiment of the present invention.
FIG. 20A is a diagram illustrating an example of a
pattern shape in a planar view of a first electrode
applicable to the embodiments of the present invention.
FIG. 20B is a diagram illustrating an example of a
pattern shape in a planar view of the first electrode
10 applicable to the embodiments of the present invention.
FIG. 21A is a diagram illustrating an example of a
pattern shape in a planar view of the first electrode
applicable to the embodiments of the present invention.
FIG. 21B is a diagram illustrating an example of a
15 pattern shape in a planar view of the first electrode
applicable to the embodiments of the present invention.
FIG. 22A is a diagram illustrating an example of a
pattern shape in a planar view of the first electrode
applicable to the embodiments of the present invention.
FIG. 22B is a diagram illustrating a portion of
pattern shapes in a planar view of the first electrode
and a second electrode applicable to the embodiments of
the present invention.
FIG. 23A is a diagram illustrating a pixel
25 arrangement in a case where pixel openings are
parallelogram-shaped.
FIG. 23B is a diagram illustrating a pattern shape
20
of the first electrode in the case where the pixel
openings are parallelogram-shaped.
FIG. 23C is a diagram illustrating a pattern shape
of the first electrode in the case where the pixel
5 openings are parallelogram-shaped.
FIG. 24 is a diagram illustrating a transflective
liquid crystal display device using a reflective
polarizing plate.
Embodiments for Carrying Out the Invention
10 Hereinafter embodiments of the present invention
will be described.
A color filter substrate for an oblique electric
field liquid crystal display device according to a
first embodiment of the present invention includes a
15 transparent substrate; a black matrix that is formed
above the transparent substrate and includes openings
having a polygonal shape in which opposite sides are
parallel to each other; a transparent conductive film
provided above the black matrix and the transparent
20 substrate within the openings; color pixels of plural
colors that are provided above the transparent
conductive film and have a polygonal shape in which
opposite sides are parallel to each other; and a first
transparent resin layer provided so as to cover the
25 color pixels, the color pixels each including, within
the opening, a region that is partitioned into two
regions respectively having different transmittances.
21
These two regions respectively having different
transmittances may be partitioned by a transparent
resin layer (second transparent resin layer) formed at
a midsection of pixel region above the transparent
5 conductive film, and/or a slit formed at the midsection
of the pixel region of the transparent conductive film.
When the two regions respectively having different
transmittances are partitioned by the transparent resin
layer (second transparent resin layer) formed at the
10 midsection of the pixel region above the transparent
conductive film, the two regions respectively having
different transmittances are partitioned into a region
of a thin color layer which covers a stripe(band)shaped
second transparent resin layer that lies above
15 the transparent conductive film within the opening and
passes through a central area of the opening, and a
region of a color layer other than that. In this case,
the second transparent resin layer may be configured to
pass through a center of the polygon-shaped opening and
20 to be disposed in parallel to one side of the polygon.
Furthermore, the relative permittivity of the second
transparent resin layer may be adjusted to be lower
than the relative permittivity of the color layer.
In the color filter substrate for the oblique
25 electric field liquid crystal display device according
to the first embodiment of the present invention as
described above, the polygon-shaped opening may be made
22
rectangular in shape in a planar view. Furthermore,
the polygon-shaped opening may be configured to have a
rectangular shape having long sides and short sides,
and to be folded in the form of the "symbol <" in a
5 planar view near the center in the direction of the
long side. Furthermore, the polygon-shaped opening may
be made to have a parallelogram shape in a planar view,
and may be made such that the respective one-halves of
the number of color pixels of the same color have
10 parallelogram shapes with two kinds of different angles
of inclination.
The color pixels of plural colors may be
configured to include pixels of three colors, namely,
red pixels, green pixels and blue pixels, and may be
15 configured such that respective relative permittivities
of the color pixels measured at a frequency for driving
the liquid crystals are in the range of from 2.9 to
4.4, and the relative permittivity of each of the color
pixels may be adjusted to be in a range of ±0.3 with
20 respect to an average relative permittivity of the red
pixels, green pixels and blue pixels.
Furthermore, the color pixels of plural colors may
be configured to include pixels of three colors,
namely, red pixels, green pixels and blue pixels, and
25 may be configured such that the magnitudes of the
respective relative permittivities of the color pixels
as measured at the frequency for driving the liquid
5
23
crystals are in a relation of red pixel > green pixel >
blue pixel.
A halogenated zinc phthalocyanine pigment may be
used as the primary coloring agent of the green pixels.
FIG. 1 is a cross-sectional diagram illustrating a
color filter substrate according to the first
embodiment of the present invention. In FIG. 1, a
black matrix 5 which is a light shielding layer having
openings that partition predetermined pixel regions is
10 formed above a transparent substrate lOa, and a
transparent conductive film 3 is formed above the
transparent substrate including this black matrix 5. A
second transparent resin layer 8 is formed at a center
of the pixel region above this transparent conductive
15 film 3 in a longitudinal direction of the openings of
the black matrix 5.
Color layers formed from green pixels 14, red
pixels 15 and blue pixels 16 are formed in the
respective pixel regions, the first transparent resin
20 layer 7 is formed thereon, and thereby a color filter
substrate 10 is constructed. Meanwhile, a reference
numeral 6 denotes an overlapping section of the color
layer.
A configuration of laminating color pixels above
25 the transparent conductive film 3 that can be used as a
common electrode has an effect that when an electric
field is formed between the transparent electrode 3 and
24
the first electrode which is a comb-shaped pixel
electrode of an array substrate that will be described
below, an equipotential line can be extended in a
thickness direction of the color pixels. By extending
5 the equipotential line, a transmittance of the liquid
crystal display device can be increased.
The opening of one pixel region can be divided, as
illustrated in FIG. 1, into a region A61 and a region
A'63, which are regions of a same transmittance, and a
10 region B62, which is a region of a different
transmittance. Examples of means for varying the
transmittance include changing of a concentration of an
organic pigment that is used as a coloring material in
these two kinds of regions with different
15 transmittances, or replacing a portion of the color
pixels with the transparent resin layer 8 so as to be
the same as the region 862. Furthermore, for example,
a technique of providing a depression in advance at the
area corresponding to the region B62 in a color pixel,
20 and filling the depression with a transparent resin to
flatten the area, may also be used. It is desirable
that these two kinds of regions with different
transmittances are flattened with a film thickness
difference of, for example, ±0.3 pm or less.
25 A height H of the overlapping section 6 of the
color layer from the surface of the pixel region is
desirably in the range of from 0.5 pm to 2 pm, which is
25
a height that affects a control of the liquid crystal
alignment (inclination of liquid crystals).
FIG. 2 illustrates a first modification example of
the color filter substrate 10 shown in FIG. 1, in which
5 the transparent conductive film 3 is formed above the
transparent substrate lOa before the formation of the
black matrix 5, and the black matrix 5 is provided
above the transparent conductive film 3. FIG. 3
illustrates a second modification example of the color
10 filter substrate 10 shown in FIG. 1, in which in the
color filter substrate 10 shown in FIG. 2, the second
transparent resin layer 8 is not formed, but a slit 18
is formed for the transparent conductive film 3.
FIG. 4 illustrates a third modification example of the
15 color filter substrate 10 shown in FIG. 1, in which in
the color filter substrate 10 shown in FIG. 1, the
second transparent resin layer 8 is not formed, but a
slit 18 is formed for the transparent conductive film
3. FIG. 5 is another modification example of the color
20 filter substrate 10 shown in FIG. 1, in which in the
color filter substrate 10 shown in FIG. 1, a slit 18 is
formed together with the second transparent resin layer
8 •
A second embodiment of the present invention
25 relates to an oblique electric field liquid crystal
display device which uses liquid crystals that exhibit
a vertical alignment as an initial alignment, is
26
intended for a liquid crystal display device of
normally black display as a primary target, and is
configured such that the color filter substrate
according to the first embodiment of the present
5 invention described above and an array substrate
including a liquid crystal driving element such as a
TFT formed thereon are disposed to face each other and
sealed, with a liquid crystal layer interposed
therebetween. Therefore, A technology according to the
10 present embodiment can be applied to a liquid crystal
display device which uses liquid crystals that exhibit
a vertical alignment as an initial alignment, and tilts
in a substrate planar direction when a voltage is
applied. In addition, in the present embodiment,
15 utilization is made of an oblique electric field
generated in an electrode configuration in which a
transparent conductive film, which is a third
electrode, is provided for a color filter substrate
with respect to a first electrode, which is a pixel
20 electrode provided for the array substrate side, and a
second electrode which has a potential different from
that of this first electrode.
In regard to such an oblique electric field liquid
crystal display device, when a driving voltage is
25 applied between the first electrode, and the second
electrode as well as the third electrode which is the
transparent conductive film, liquid crystal molecules
27
in a region of liquid crystals corresponding to the
opening move so as to tilt in opposite directions that
are axially symmetric with respect to a straight line
which passes through a center of the opening and
5 bisects the opening in a planar view.
The first electrode and the second electrode can
adopt a shape having a linear pattern such as a combshaped
pattern. Longitudinal directions of patterns of
these first electrode and second electrode may be
10 divided in two directions, or in four or more
directions, within a pixel that is formed for the
polygon-shaped opening of the black matrix.
As shown in a schematic cross-sectional diagram of
the liquid crystal display device of FIG. 6 or FIG. 14
15 to which the present embodiment is applied, the linear
pattern of the second electrode can be made to protrude
in a width direction from the linear pattern of the
first electrode. The protrusion section 2a, which will
be described in detail below, has an action of setting
20 a direction of tilt of liquid crystals (direction of an
alignment at a time of liquid crystal display) after a
driving voltage is applied to the liquid crystals 17.
Those liquid crystals located close to the surface on
the color filter substrate are operated by an oblique
25 electric field extending from the first electrode
toward the direction of the third electrode which is a
transparent conductive film. By adjusting the
28
direction in which the liquid crystals would tilt under
the action of this oblique electric field, to match the
direction of the protrusion section 2a described above,
liquid crystal molecules in one liquid crystal domain
5 within a pixel can be caused to tilt at a high speed in
the same direction. When two, or four or more of the
liquid crystal domains are formed within in one pixel,
a wide field of vision can be secured.
The TFT of the liquid crystal display device may
10 be formed from silicon, but when the TFT is formed
from, for example, a complex metal-oxides
semiconductor, the aperture ratio of the pixels can be
increased. Representative examples of the channel
material for a complex metal-oxides semiconductor TFT
15 include complex metal-oxides of indium, gallium and
zinc called IGZO.
Furthermore, among the liquid crystals that can be
applied to the present embodiment, liquid crystals
which exhibit negative dielectric constant anisotropy
20 and have an initial vertical alignment can be suitably
applied. In this case, a vertically aligned film is
used; however, an alignment treatment such as a photoalignment
or rubbing can be omitted by using the
technology according to the present embodiment. As
25 will be described below, in the present embodiment,
strict control of the tilt angle to 89° that is
required in conventional VA (vertical alignment) is
29
unnecessary, and the liquid crystals having the initial
vertical alignment of 90 0 can be used. Furthermore, in
the case of the initial vertical alignment, unlike a
liquid crystal display device of initial horizontal
5 alignment, strict optical axis alignment of a
polarizing plate or retardation plate that is attached
to one surface or both surfaces of a liquid crystal
display device is not required. In the case of initial
vertical alignment, the retardation upon no voltage
10 application is 0 nm, and for example, even if there is
a slight shift from a slow axis of the polarizing
plate, a light leakage does not easily occur, and an
almost perfect black display can be obtained. In the
liquid crystals in the initial horizontal alignment
15 state, a light leakage occurs if there is an optical
axis shift of several degrees from the polarizing
plate, and it is disadvantageous from a viewpoint of a
contrast of the liquid crystal display device.
In the liquid crystal display device according to
20 the second embodiment of the present invention, a
movement of the liquid crystal molecules on the color
filter substrate and the liquid crystal molecules above
the array substrate that is disposed to face the color
filter substrate will be described with reference to
25 FIG. 6, FIG. 7, FIG. 8, FIG. 9.
FIG. 6 is a schematic cross-sectional diagram of a
liquid crystal display device according to the second
30
embodiment of the present invention. Regarding the
color filter substrate 10, the substrate illustrated in
FIG. 5 is used. FIG. 7 is a partially magnified
diagram of FIG. 6.
5 As illustrated in FIG. 7, liquid crystals that
exhibit initial vertical alignment, except for a liquid
crystal molecule 17a in the vicinity of the shoulders
of the black matrix 5 and the color layer overlapping
section 6, is aligned vertically at a surface of the
10 colo~ filter substrate 10 and a surface of the array
substrate 20 (liquid crystal molecules 17b to 17f). A
liquid crystal molecule 17a is obliquely aligned in an
initial alignment state at the shoulder of the color
layer overlapping section 6.
15 As illustrated in FIG. 8, when a voltage is
applied to the first electrode 1 which is a pixel
electrode, the liquid crystal molecule 17a in the
vicinity of the shoulder of the color layer overlapping
section 6 starts to tilt in a direction of an arrow so
20 as to be perpendicular to a line of electric force 30a
that is directed from the first electrode 1 toward a
direction of the third electrode 23, which is a common
electrode. As the third electrode 3 at the color layer
overlapping section 6 is formed above the black matrix
25 5, the third electrode is closer to the first electrode
1, and thus, a stronger effective voltage is applied to
the liquid crystal molecule 17a than to other liquid
31
crystal molecules 17d, 17e and 17f. Furthermore, the
liquid crystal molecules in the areas other than the
vicinity of the surface of the color filter substrate
10 tilt in the horizontal direction of the substrate
5 surface as the tilting of the liquid crystal molecule
17a propagates in the planar direction. Furthermore,
the liquid crystal molecules 17e and 17f that are
distant from the first electrode 1 at the center of the
pixel tilt similarly so as to be vertical to the
10 direction of the lines of electric force 30e and 30f
from the first electrode 1. However, since the liquid
crystal molecules 17e and 17f are at positions slightly
distant from the first electrode 1, and the angle of
tilt decreases in accordance with this distance.
15 FIG. 9 illustrates a final state of alignment of the
liquid crystal molecules. In the diagram, a reference
numeral 2c represents a second electrode (common
electrode) that is positioned below the black matrix 5.
Meanwhile, in a configuration in which the black matrix
20 5 is formed above the third electrode, the liquid
crystal molecule 17a in the vicinity of the shoulder of
the color layer overlapping section 6 can be subjected
to a strong electric field by using a material having a
high dielectric constant as the black matrix base
25 material.
On the other hand, in regard to the liquid crystal
molecules that are in contact with the array substrate
~..•. .,
32
20 side, liquid crystal molecules 17g and 17h in the
vicinity of the first electrode 1, which is a pixel
electrode, and the second electrode 2, which is a
common electrode, particularly above the protruding
5 section of the second electrode 2 tilt significantly
and very quickly immediately after voltage application,
so as to be perpendicular to the lines of electric
force 30g and 30h. The reason why the movement of the
liquid crystal molecules 17g and 17h is so fast is that
10 the distances from the first electrode 1 and the second
electrode 2 are extremely short, and therefore, these
liquid crystal molecules are subjected to the strongest
electric field. When triggered by a movement of the
liquid crystal molecules 17g and 17h, the liquid
15 crystals within the pixel (strictly speaking, one
liquid crystal domain) tilt all at once in the same
direction in a manner synchronized with the movement of
the liquid crystal molecule 17a and the like in the
vicinity of the shoulder. However, as described above,
20 the angles of inclination at the liquid crystals above
the third electrode 3 and of the liquid crystal
molecules at positions that are distant from the first
electrode 1 become smaller.
Meanwhile, in order to make tilting of the liquid
25 crystal molecules above the protruding section easier
for orientation, processing such as tapering of an end
of the first electrode, increasing a film thickness of
33
the first electrode, etching of an area of an
insulating layer below the first electrode, or
decreasing a thickness of the insulating layer, can
also be applied.
5 After the application of a driving voltage to the
liquid crystals, as illustrated in FIG. 8, the liquid
crystals 17 tilt symmetrically under the effect of the
first electrode 1, second electrode 2, and third
electrode 3 that are disposed symmetrically with
10 respect to the center of the pixel, as illustrated in
FIG. 6. Due to this symmetry, the viewing angle can be
widened at the time of liquid crystal display.
In a normal display region shown in FIG. 6, a
gradation display is carried out according to the
15 magnitude of the voltage applied between the first
electrode, and the second and third electrodes. In a
dynamic display region, a light transmission is
initiated at a voltage higher than that for the normal
display region. In FIG. 8, as a light is transmitted
20 through an area of thin color layer 19 above the second
transparent resin layer 8, a brighter display can be
achieved. That is, by applying a voltage that is
higher than the driving voltage applied between the
first electrode and the second and third electrodes, a
25 bright dynamic display is enabled.
In addition, the brightness of the dynamic display
can be independently adjusted by providing two active
34
elements (TFT elements) in one pixel, and for example,
separately driving a set of the first electrodes on the
inner side close to the dynamic display region shown in
FIG. 9 by using one TFT element.
5 FIG. 10 shows a schematic cross-sectional diagram
of a liquid crystal display device using the color
filter substrate 10 shown in FIG. 1. The movement of
the liquid crystal molecules of this liquid crystal
display device is also similar to that of the liquid
10 crystal display device described above.
A schematic cross-sectional diagram of a
transflective type liquid crystal display device, which
is a third embodiment of the present invention, is
shown in FIG. 11. The array substrate 30 of the liquid
15 crystal display device illustrated in FIG. 11 includes,
at the center of the pixel, a light reflective film 21
based on an aluminum alloy thin film. The light
reflective film is electrically independent.
The liquid crystal display in a transmission
20 region is a normal gradation display region based on
transmission, similarly to the normal display region
shown in FIG. 6 and FIG. 7. In a reflection region, by
adjusting the inclination of the liquid crystal
molecules in this region, the retardation (~nd) is
25 reduced approximately a half of the retardation of the
transmission region, and thereby, a reflective display
utilizing external light is enabled. Liquid crystals
35
28 in the reflection region are such that since the
liquid crystals are at positions distant from the first
electrode 1, a change in alignment of the liquid
crystal molecules associated with a change in the
5 applied voltage becomes mild. An applied voltage
dependencies of a transmitted light and reflected light
can be made analogous by utilizing the difference
between the reflective display region and the
transmissive display region where a change in alignment
10 of the liquid crystal molecules is steep. Accordingly,
a satisfactory liquid crystal display may be obtained,
in which the reflective display and the transmissive
display can be driven under the same driving conditions
at a high contrast and without any tone reversal. In
15 the present embodiment, the liquid crystal cell
thickness adjusting layer needed in the reflection
region (a thickness adjusting layer that makes the
thickness to 1/2 of the thickness of liquid crystals at
the transmission region) can be made unnecessary.
,I
i
20 Next, an action of a slit formed in the
transparent conductive film (a fine line-shaped opening
where the transparent conductive film is not formed) of
the color filter substrate of the liquid crystal
display device according to a fourth embodiment of the
25 present invention will be explained with reference to
FIG. 12, FIG. 13, FIG. 14, FIG. 15, and FIG. 16.
FIG. 14 to FIG. 16 are partially magnified diagrams of
36
FIG. 11, and are explanatory diagrams for movements of
various liquid crystals above the color filter
substrate 40 and above the array substrate 50.
FIG. 12 and FIG. 13 are schematic cross-sectional
5 diagrams of a liquid crystal display device according
to a fourth embodiment of the present invention. The
first electrode 1 and the second electrode 2 of the
protrusion electrode configuration are disposed
symmetrically with respect to the center of the pixel.
10 At the center of the pixel of the color filter
substrate 40, a slit 18 at which a transparent
conductive film is not formed is formed in a direction
perpendicular to the paper face.
The alignment and operation of the liquid crystals
15 17 in the vicinity of the color filter substrate
surface will be described by using FIG. 14 and FIG. 15.
As illustrated in FIG. 14, when no voltage is applied,
the liquid crystals 17 except for the liquid crystal
molecule 17a are aligned perpendicularly to the surface
20 of the color filter substrate 10. As illustrated in
FIG. 15, when a voltage is applied between the first
electrode 1 and the third electrode 3, the liquid
crystal molecule 17a in the vicinity of the shoulder of
the color layer overlapping section 6 starts to tilt in
25 a direction of an arrow so as to be perpendicular to a
line of electric force 41a. The liquid crystal 17f in
the vicinity of the slit 18 at the center of the pixel
37
starts to tilt in a direction of an arrow so as to be
perpendicular to a line of electric force 41f. When
triggered by these liquid crystals, liquid crystals on
the side of the color filter substrate surface tilt
5 respectively in symmetrically opposite directions with
respect to the center of the pixel.
An alignment and operation of the liquid crystals
17 in the vicinity of the array substrate surface will
be described by using FIG. 16 and FIG. 17. FIG. 16
10 illustrates liquid crystals of an initial vertical
alignment. FIG. 17 illustrates liquid crystal
molecules 17g, 17h and 17i that start to tilt above the
protruding section 2a of the first electrode 1 and the
second electrode after voltage application. On the
15 array substrate side, when triggered by these liquid
crystals, the liquid crystals tilt all at once
respectively in symmetrically opposite directions with
respect to the center of the pixel.
FIG. 18 and FIG. 19 are partially magnified
20 diagrams explaining a liquid crystal display device
according to a fifth embodiment of the present
invention, in which a color filter substrate 60
provided with a set of linear conductors 4 in the
vicinity of the center of the pixel at the first
25 transparent resin layer 7 is used. FIG. 19 illustrates
movements of the liquid crystal molecules after voltage
application. The liquid crystal molecule 17f in the
38
vicinity of the center of the pixel tilts more rapidly
and more significantly in a direction of an arrow than
the liquid crystal molecule 17f in FIG. 17 as shown
above. This is because, since linear conductors 4
5 having the same common potential as that of the third
electrode are formed at a position closer to the first
electrode 1, the liquid crystal molecule 17f shown in
FIG. 19 is subjected to a stronger electric field, and
therefore, response becomes faster. Meanwhile, in
10 FIG. 18 and FIG. 19, a slit is formed for the
transparent conductive film 3, which is a third
electrode; however, the slit may not be formed. Also,
in the embodiment described above, the overlapping
section 2b of the first electrode and the second
15 electrode can be used as a supplementary capacity.
Here, technical terms used herein will be
described briefly.
The black matrix is a light shielding pattern
provided along a periphery of a pixel, which is the
20 smallest unit of display, or on two sides of the pixel,
in order to increase a contrast of the liquid crystal
display. The light shielding layer is a light
shielding coating film in which a light shielding
pigment is dispersed in a transparent resin, is
25 generally imparted with photosensitivity, and is
obtained by forming a pattern by a photolithographic
technique including exposure and development.
39
The color layer refers to a coating film of a
coloring composition in which an organic pigment is
dispersed in a transparent resin. A pattern formed
such that the color layer is superimposed with a
5 portion of the black matrix by a known
photolithographic technique is called a color pixel.
An effective size of the color pixel is almost the same
as that of the opening of the black matrix.
Regarding the polygon in which sides that face
10 each other are parallel, for example, a quadrilateral
shape such as a rectangular shape, a parallelogram
shape, a hexagonal shape, and the polygon that is
folded at the center of the pixel as shown in FIG. 20B
can be used.
15 In the present embodiment, liquid crystals having
negative dielectric constant anisotropy can be used.
For example, as the liquid crystals having negative
dielectric constant anisotropy, nematic liquid crystals
having a birefringence of about 0.1 at near room
20 temperature can be used. It is not necessary to
particularly limit the thickness of the liquid crystal
layer, but ~nd of the liquid crystal layer that can be
effectively used in the present embodiment is
approximately in the range of 250 nm to 500 nm in the
25 transmissive display region or in transmissive display.
An average value of ~nd of the liquid crystal layer at
the semi-reflection section can be adjusted to 125 nm
40
to 250 nm which is one-half by adjusting the
inclination of the liquid crystal molecules in the
reflective display region.
In the Examples of the present invention that will
5 be described in detail below, a liquid crystal material
having fluorine atoms in the molecular structure
(hereinafter, described as a fluorine-based liquid
crystal) can be used as the liquid crystal material.
Furthermore, at the time of the application of a
10 voltage for liquid crystal driving, since a
substantially strong electric field is generated at the
protruding section of the first electrode and the
second electrode, liquid crystal driving can be
achieved by using a liquid crystal material having a
15 lower dielectric constant (having lower dielectric
constant anisotropy) than that of the liquid crystal
materials used in conventional vertical alignment. In
general, a liquid crystal material having low
dielectric constant anisotropy has lower viscosity, and
20 when an electric field intensity of the same extent is
applied, response may be obtained at a higher speed.
Furthermore, since a fluorine-based liquid crystal has
a low dielectric constant, incorporation of ionic
impurities occurs less, deterioration of performance
25 such as a decrease in the voltage maintain rate caused
by impurities occurs at a lower level, and display
unevenness does not easily occur.
41
In the present invention, liquid crystals of
horizontal alignment can also be applied. In the case
of the liquid crystals of initial horizontal alignment,
the liquid crystals stand in a direction perpendicular
5 to the substrate surface when a driving voltage is
applied, and thus, a light is transmitted. Application
of liquid crystals having positive dielectric constant
anisotropy and having initial horizontal alignment is
also technically possible. However, in order to secure
10 initial horizontal alignment, an alignment treatment
such as a rubbing for an alignment film is needed to
definitively determine a direction of alignment of the
liquid crystals. In the case of liquid crystals having
an initial alignment which is vertical, a rubbing
15 treatment or a photo-alignment treatment can be
omitted. From this viewpoint, in the present
invention, it is preferable to apply liquid crystals of
vertical alignment.
Regarding a material of the first electrode 1 and
20 the second electrode 2 of the array substrate side of
the liquid crystal display device according to the
present embodiment, a conductive metal oxide such as
ITO described above can be used. Alternatively, a
metal having higher conductivity than a metal oxide can
25 be employed. Furthermore, in the case of a reflective
type or transflective type liquid crystal display
device, a thin film of aluminum or an aluminum alloy
42
may be used in any of the first electrode 1 and the
second electrode 2.
As shown in FIG. 6 or the like, the first
electrode 1, the second electrode 2, and a metal wiring
5 of an active element, and the like are formed by
inserting therebetween an insulating layer 22 formed of
silicon nitride (SiNx) or silicon oxide (SiOx). A film
thickness of the insulating layer 22 is not
particularly limited since the film thickness depends
10 on driving conditions for liquid crystals, but the film
thickness can be selected from, for example, the range
of 100 nm to 600 nm. In FIG. 7, graphic illustration
of a TFT element or a metal wiring connected to a TFT
element is omitted.
15 In addition, a technology for forming,
respectively, a gate wiring or a source wiring by using
a single layer of an aluminum alloy having a low
contact property for ITO, which is an electrically
conductive metal oxide, is disclosed in, for example,
20 Jpn. Pat. Appln. KOKAI Publication No. 2009-105424.
Furthermore, further laminating an insulating layer
above the first electrode has an effect of alleviating
burn-in of liquid crystals (affected by deviation or
accumulation of electric charge) at the time of liquid
25 crystal driving, which is preferable. Furthermore, a
light reflective film may also be provided as
illustrated in FIG. 11, by using a thin film of an
43
aluminum alloy. The reflective film may be made
electrically independent, or an active element that is
connected to the reflective film can be separately
formed in addition to the active element that is
5 connected to the first electrode, and a different
voltage can be applied thereto.
In the comb-shaped electrode pattern, two or more
linear conductors each having a width of from 2 ~m to
20 ~m may be electrically connected, and the connection
10 area may be either on one side or on both sides. The
interval of the comb-shaped pattern may be selected
approximately in the range of 3 ~m to 100 ~m, in
accordance with the liquid crystal cell conditions and
the liquid crystal material. The comb-shaped pattern
15 can be formed by varying the formation density or pitch
of the comb-shaped pattern and the electrode width
within one pixel.
The second electrode 2 can be formed, for example,
as illustrated in FIG. 6 or the like, so as to protrude
20 in one direction of the electrode width of the first
electrode 1. The protruding direction becomes axially
symmetric or point-symmetric with respect to the center
of the pixel. The amount of protrusion can be adjusted
in a wide variety with the liquid crystal material or
25 driving conditions used, or a dimension such as the
liquid crystal cell thickness. The protrusion section
2a is sufficient even with a small amount of from 1 ~m
44
to 5 pm. The overlapping section 2b can be used as a
supplementary capacity related to the liquid crystal
driving.
Meanwhile, a direction of protrusion of the second
5 electrode 2 (hereinafter, a protrusion configuration of
the first electrode 1 and the second electrode 2 may be
simply referred to as a protruding electrode
configuration) is desirably in opposite directions in
point symmetry or axial symmetry with respect to the
10 center of the pixel. Furthermore, a pattern protruding
to a direction opposite to the direction facing toward
the second transparent resin layer 8 in a planar view
is desirable.
The comb-shaped electrode pattern may be V-shaped
15 or in an oblique direction in a planar view.
Alternatively, the first electrode 1 and the second
electrode 2 may have, as illustrated in FIG. 22A and
FIG. 22B, a comb-shaped pattern in which the direction
is changed by 90° in every 1/4 pixel unit. Thereby,
20 when a voltage for driving the liquid crystals is
applied, movements are partitioned into four directions
in point symmetry in a planar view, and the display
region of a pixel is partitioned into four movement
regions. In this case, the comb-shaped electrode can
25 be inclined in the direction of 45° with respect to the
center line of the pixel. These electrode patterns are
desirably point-symmetric or axially symmetric as
45
viewed from the center of the pixel. The numbers of
the first electrode 1 and the second electrode 2, the
electrode pitch, and the electrode width can be
appropriately selected.
5 Examples of a pattern shape in a planar view of
the first electrode 1 that can be applied to the
embodiments described above are presented in FIG. 20A,
FIG. 20B, FIG. 21A, FIG. 21b, FIG. 22A, and FIG. 22B.
In the first electrode 1, a voltage for driving the
10 liquid crystals is applied, but the second electrode 2
and the third electrode, which is the transparent
conductive film 3 disposed on the color filter
substrate side, can have a common potential (common).
Meanwhile, in FIG. 20A, FIG. 20B, FIG. 21A, FIG. 21B,
15 FIG. 22A, and FIG. 22B, a reference numeral 25
represents an opening (polygonal color pixel) of the
black matrix 5, and a reference numeral 9 represents
the direction in which the liquid crystal molecules
would tilt.
20 Among the technical features related to the
embodiments described above, the movement or action of
liquid crystals in a liquid crystal display device
equipped with a protruding electrode configuration may
be summarized as follows.
25 (1) Alignment treatments that are conventionally
required can be omitted by using liquid crystals having
initial vertical alignment and having negative
46
dielectric constant anisotropy as liquid crystals.
(2) The formation of a domain of liquid crystals
for an extension of viewing angle is subject to the
protruding electrode configuration. That is, by
5 configuring the protruding electrode configuration into
an inclined pattern in two different directions or four
or more different directions within one pixel, liquid
crystal domains can be formed after applying a driving
voltage to the liquid crystals, and the viewing angle
10 can be widened.
(3) The liquid crystal molecules on the color
filter substrate side have an initial alignment that is
vertical, but an oblique electric field at the time of
application of a driving voltage to the liquid crystal
15 molecules can be used in the tilt of the liquid crystal
molecules (direction of alignment of the liquid
crystals after voltage application) .
(4) By adjusting the tilt of the liquid crystals
on the color filter substrate side to be in line with
20 the protrusion direction of the protruding electrode
configuration, declination of the liquid crystals is
decreased, and also, a high-speed liquid crystal
display with a high transmittance is enabled.
The movement and action of the liquid crystals
25 described above are common in the embodiments described
above and in the Examples that will be described below.
In the embodiment described above, the relative
47
permittivity of the color layer is a relative important
characteristic; however, since the relative
permittivity is almost definitely determined by the
ratio of the organic pigment that is added as a
5 coloring agent with respect to the transparent resin
(color reproduction as a color filter), it is difficult
to greatly change the relative permittivity of the
color layer. In other words, the kind or content of
the organic pigment in the color layer is set based on
10 the color purity required for a liquid crystal display
device, and accordingly, the relative permittivity of
the color layer is also almost determined. Meanwhile,
the relative permittivity can be adjusted to 4 or
greater by increasing the ratio of the organic pigment
15 and thereby reducing the color layer into a thin film.
Furthermore, the relative permittivity can be slightly
increased by using a high refractive index material as
the transparent resin. The relative permittivity of a
color layer that uses an organic pigment falls
20 approximately in the range of from 2.9 to 4.5.
The relative permittivity of the color layer or
light shielding layer in the Examples that will be
described below was measured by using an Impedance
Analyzer Model 1260 manufactured by Solartron ISA under
25 the conditions of a voltage of 3 V at frequencies of
120, 240 and 480 Hz. The measurement sample is a
product obtained by applying and curing a color layer
48
or a light shielding layer (the film thickness is the
same as that used in Examples that will be described
below) above a glass substrate on which a conductive
film formed from an aluminum thin film has been formed
5 patternwise, and a conductive film pattern formed from
an aluminum thin film is formed on this color layer.
Hereinafter, the relative permittivity of the color
layer may be referred to as a relative permittivity of
a color pixel.
10 In regard to the relative permittivity of a color
pixel of the color filter, in order to avoid color
unevenness or light leakage in the liquid crystal
display, the difference in the values of relative
permittivity between color pixels of different colors
15 can be adjusted to ±0.3. In a liquid crystal display
device in the driving mode according to the present
invention or a Fringe-Field Switching (FFS) mode, if
the difference in the relative permittivity between
color pixels is larger than 0.8 or 1.0, color
20 unevenness or light leakage in the liquid crystal
display may occur.
As will be described in detail in the Examples
given below, the inventors of the present invention
conducted an investigation and found that the relative
25 permittivity of a color pixel can be suppressed to 4.4
or less by means of the selection of an organic pigment
as a coloring agent, and the selection of the pigment
49
proportion, and materials other than the resin or the
dispersant material for the parent material. As will
be described below, for the organic pigment for a green
pixel, a halogenated zinc phthalocyanine green pigment
5 is preferred to a halogenated copper phthalocyanine
green pigment. When the latter is used as a primary
coloring agent for a green pixel, the relative
permittivity of the green pixel can be made small, and
it is easy to make the relative permittivity of the
10 green pixel even with the values of the relative
permittivity of a red pixel and a blue pixel.
Alternatively, in the case where the rise of liquid
crystals during liquid crystal driving is faster on the
shorter wavelength light side (blue pixel) and slower
15 on the longer wavelength light side (red pixel), the
magnitudes of the relative permittivity of color pixels
can be adjusted in order of the wavelength of light.
Meanwhile, using a halogenated zinc phthalocyanine
green pigment as a primary coloring material for a
20 green pixel means that in the case of using two or more
pigments as a mixture, the amount of addition of the
halogenated zinc phthalocyanine green pigment is the
largest.
Furthermore, conditions that do not impede the
25 liquid crystal driving can be provided by making the
values of the relative permittivity of the color filter
constituent members to be smaller than the value of
50
dielectric constant anisotropy 62 of the liquid crystal
used in a liquid crystal display device. For the
formation of color pixels of the color filter,
photosensitive acrylic resins are usually used. In
5 general, the relative permittivities of transparent
resins such as acrylic resins are approximately close
to 2.8. As the inventors of the present invention
conducted a study, they found that the lower limit of
the relative permittivity of color pixels, which are
10 dispersion systems of organic pigments, is
approximately 2.9. In regard to the light shielding
layer used in the formation of the black matrix, the
relative permittivity value thereof can be set to 6 or
greater, for example 16, by adjusting the amount of
15 addition of carbon as a black coloring agent to the
transparent resin. When the coloring agents used in
the light shielding layer are all selected from organic
pigments, the relative permittivity values can be
adjusted to small values of 4.4 or less.
20 In a liquid crystal display device in an In-Plane
Switching (IPS) mode or an FFS mode, which are both
representative modes for liquid crystal driving with
high contrast and a wide viewing angle, a liquid
crystal having dielectric constant anisotropy values of
25 approximately 4.5 is frequently used for the purpose of
high speed response, or in order to decrease the
threshold value of the driving voltage. In the case of
51
applying these liquid crystals to the embodiments of
the present invention, the relative permittivity of the
color layer or the transparent resin layer in the color
filter configuration is desirably 4.4 or less. At
5 least, if the relative permittivity of the color layer
or the transparent resin layer is equal to the value of
dielectric constant anisotropy of the liquid crystal in
use, a color filter which poses less hindrance on the
formation of an electric field between the first
10 electrode and the third electrode can be provided. In
the case of a liquid crystal having vertical
orientation and negative dielectric constant
anisotropy, since reliability is affected depending on
the driving conditions, a liquid crystal having an
15 absolute value of the dielectric constant anisotropy of
3.8 or less may be selected. The relative permittivity
of the color layer or transparent resin layer in the
color filter configuration of the present invention is
more preferably 3.8 or less. In addition, when a resin
20 material having a low relative permittivity is used for
the first and second transparent resin layers, the
apparent relative permittivity as a pixel of a color
filter can be made lower than that of the simple
material of a color layer.
25 Hereinafter, examples of transparent resins,
organic pigments and the like that can be used in the
color filter substrate according to the embodiments
52
discussed above will be described.
(Transparent resin)
The photosensitive color composition used in the
formation of the light shielding layer or the color
5 layer further contains, in addition to the pigment
dispersion, a polyfunctional monomer, a photosensitive
resin, a non-photosensitive resin, a polymerization
initiator, a solvent, and the like. Highly transparent
organic resins that can be used in the embodiments of
10 the present invention, such as photosensitive resins
and non-photosensitive resins, are collectively called
transparent resin.
Transparent resins include thermoplastic resins,
thermosetting resins, and photosensitive resins.
15 Examples of the thermoplastic resins include a butyral
resin, a styrene-maleic acid copolymer, a chlorinated
polyethylene, chlorinated polypropylene, polyvinyl
chloride, a vinyl chloride-vinyl acetate copolymer, a
polyvinyl acetate, a polyurethane-based resin, a
20 polyester resin, an acrylic resin, an alkyd resin, a
polystyrene resin, a polyamide resin, a rubber-based
resin, a cyclized rubber-based resin, a cellulose,
polybutadiene, polyethylene, polypropylene, and a
polyimide resin. Furthermore, examples of the
25 thermosetting resins include an epoxy resin, a
benzoguanamine resin, a rosin-modified maleic acid
resin, a rosin-modified fumaric acid resin, a melamine
53
resin, a urea resin, and a phenolic resin. Regarding
the thermosetting resin, a product produced by allowing
a melamine resin to react with a compound containing an
isocyanate group, may also be used.
5 (Alkali-soluble resin)
In the formation of a light shielding layer, a
light scattering layer, a color layer, and a cell gap
control layer that are used in the embodiments
described above, it is preferable to use a
10 photosensitive resin composition capable of forming a
pattern by photolithography. The transparent resin
contained in this photosensitive resin composition is
desirably a resin imparted with alkali solubility. The
alkali-soluble resin is not particularly limited as
15 long as it is a resin containing a carboxyl group or a
hydroxyl group. Examples thereof include an epoxy
acrylate-based resin, a novolac-based resin, a
polyvinylphenol-based resin, an acrylic resin, a
carboxyl group-containing epoxy resin, and a carboxyl
20 group-containing urethane resin. Among them, an epoxy
acrylate-based resin, a novolac-based resin, and an
acrylic resin are preferred, and particularly, an epoxy
acrylate-based resin or a novolac-based resin is
preferred.
25 (Acrylic resin)
Representative examples of the transparent resins
that can be employed in the above embodiments include
54
the following acrylic resins.
Examples of the acrylic resin include polymers
obtained by using, as monomers, (meth)acrylic acid;
alkyl (meth)acrylates such as methyl (meth) acrylate,
5 ethyl (meth) acrylate, propyl (meth) acrylate, butyl
(meth) acrylate, t-butyl (meth) acrylate, pentyl
(meth) acrylate, and lauryl (meth) acrylate; hydroxyl
group-containing (meth)acrylates such as hydroxyethyl
(meth)acrylate and hydroxypropyl (meth) acrylate; ether
10 group-containing (meth)acrylates such as ethoxyethyl
(meth)acrylate and glycidyl (meth) acrylate; and
alicyclic (meth)acrylates such as cyclohexyl
(meth) acrylate, isobornyl (meth) acrylate, and
dicyclopentenyl (meth) acrylate.
15 Meanwhile, the monomers listed above can be used
singly, or two or more kinds can be used in
combination. Furthermore, copolymers with compounds
capable of copolymerizing with these monomers, such as
styrene, cyclohexylmaleimide and phenylmaleimide, may
20 also be used.
Furthermore, a resin having photosensitivity can
be obtained by allowing, for example, a copolymer
obtained by copolymerizing a carboxylic acid having an
ethylenically unsaturated group, such as (meth)acrylic
25 acid, to react with a compound containing an epoxy
group and an unsaturated double bond, such as glycidyl
methacrylate; or adding a carboxylic acid-containing
55
compound such as (meth)acrylic acid to a polymer of an
epoxy group-containing (meth)acrylate such as glycidyl
methacrylate, or a copolymer thereof with another
(meth) acrylate.
5 Furthermore, a resin having photosensitivity can
be obtained by allowing, for example, a polymer having
hydroxyl groups, of a monomer such as hydroxyethyl
methacrylate, to react with a compound having an
isocyanate group and an ethylenically unsaturated
10 group, such as methacryloyloxyethyl isocyanate.
Furthermore, as described above, a resin having
carboxyl groups can be obtained by allowing a copolymer
of hydroxyethyl methacrylate or the like, having plural
hydroxyl groups, to react with a polybasic acid
15 anhydride, and introducing carboxyl groups into the
copolymer. The method for producing a resin having
carboxyl groups is not intended to be limited to this
method only.
Examples of the acid anhydride used in the
20 reaction described above include, for example, malonic
anhydride, succinic anhydride, maleic anhydride,
itaconic anhydride, phthalic anhydride,
tetrahydrophthalic anhydride, hexahydrophthalic
anhydride, methyltetrahydrophthalic anhydride, and
25 trimellitic anhydride.
The solid component acid value of the acrylic
resin described above is preferably 20 mg KOH/g to
56
180 mg KOH/g. If the acid value is less than
20 mg KOH/g, the development rate of the photosensitive
resin composition is so slow that the time required for
development increases, and thus productivity tends to
5 deteriorate. Furthermore, if the solid component acid
value is larger than 180 mg KOH/g, on the contrary, the
development rate is so fast that inconveniences such as
peeling of the pattern and chipping of the pattern
after development tend to occur.
10 Furthermore, when the acrylic resin has
photosensitivity, the double bond equivalent of this
acrylic resin is preferably 100 or greater, more
preferably 100 to 2000, and most preferably 100 to
1000. If the double bond equivalent is greater than
15 2000, sufficient photocurability may not be obtained.
(Photopolymerizable monomer)
Examples of the photopolymerizable monomer include
various acrylic acid esters and methacrylic acid esters
such as 2-hdyroxyethyl (meth) acrylate, 2-hydroxypropyl
20 (meth) acrylate, cyclohexyl (meth) acrylate, polyethylene
glycol di(meth)acrylate, pentaerythritol
tri(meth)acrylate, trimethylolpropane
tri(meth)acrylate, dipentaerythritol
hexa(meth)acrylate, tricyclodecanyl (meth) acrylate,
25 melamine (meth) acrylate, and epoxy (meth) acrylate;
(meth)acrylic acid, styrene, vinyl acetate,
(meth)acrylamide, N-hydroxymethyl (meth)acrylamide, and
57
acrylonitrile.
Furthermore, it is preferable to use a
polyfunctional urethane acrylate having (meth)acryloyl
group, which is obtainable by allowing (meth)acrylate
5 having a hydroxyl group to react with a polyfunctional
isocyanate. Meanwhile, the combination of
(meth)acrylate having a hydroxyl group and a
polyfunctional isocyanate is arbitrary, and is not
particularly limited. Furthermore, one kind of a
10 polyfunctional urethane acrylate may be used alone, or
two or more kinds may also be used in combination.
(Photopolymerization initiator)
Examples of the photopolymerization initiator
include acetophenone-based compounds such as 4-
15 phenoxydichloroacetophenone, 4-tbutyldichloroacetophenone,
diethoxyacetophenone, 1-(4isopropylphenyl)-
2-hydroxy-2-methylpropan-1-one, 1hydroxycyclohexyl
phenyl ketone, and 2-benzyl-2dimethylamino-
1-(4-morpholinophenyl)-butan-1-one;
20 benzoin-based compounds such as benzoin, benzoin methyl
ether, benzoin ethyl ether, benzoin isopropyl ether,
and benzyl dimethyl ketal; benzophenone-based compounds
such as benzophenone, benzoylbenzoic acid, methyl
benzoylbenzoate, 4-phenylbenzophenone,
25 hydroxybenzophenone, acrylated benzophenone, and 4benzoyl-
4'-methyldiphenyl sulfide; thioxanthone-based
compounds such as thioxanthone, 2-chlorothioxanthone,
58
2-methylthioxanthone, isopropylthioxanthone, and 2,4diisopropylthioxanthone;
triazine-based compounds such
as 2,4,6-trichloro-s-triazine, 2-phenyl-4,6bis(
trichloromethyl)-s-triazine, 2-(p-methoxyphenyl)-
5 4,6-bis(trichloromethyl)-s-triazine, 2-(p-tolyl)-4,6bis(
trichloromethyl)-s-triazine, 2-biphenyl-4,6bis(
trichloromethyl)-s-triazine, 2,4bis(
trichloromethyl)-6-styryl-s-triazine, 2-(naphth-lyl)-
4,6-bis(trichloromethyl)-s-triazine, 2-(4-
10 methoxynaphth-l-yl)-4, 6-bis (trichloromethyl)-striazine,
2,4-trichloromethyl-(piperonyl)-6-triazine,
and 2,4-trichloromethyl(4'-methoxystyryl)-6-triazine;
oxime ester-based compounds such as 1,2-octanedione, 1[
4-(phenylthio)-,2-(O-benzoyloxime)], and O-(acetyl)-N-
15 (1-phenyl-2-oxo-2-(4'-
methoxynaphthyl) ethylidene) hydroxylamine; phosphinebased
compounds such as bis(2,4,6trim~
thylbenzoyl)phenylphosphineoxide and 2,4,6trimethylbenzoyldiphenylphosphine
oxide; quinone-based
20 compounds such as 9,10-phenanthrenequinone, camphorquinone,
and ethylanthraquinone; borate-based
compounds; carbazole-based compounds; imidazole-based
compounds; and titanocene-based compounds. For an
enhancement of sensitivity, oxime derivatives (oxime-
25 based compounds) are effective. These can be used
singly, or two or more kinds can be used in
combination.
59
(Sensitizer)
The photopolymerization initiator is preferably
used in combination with a sensitizer. As the
sensitizer, compounds such as ~-acyloxy ester,
5 acylphosphine oxide, methylphenyl glyoxylate, benzyl9,10-
phenanthrenequinone, camphor-quinone,
ethylanthraquinone, 4,4'-diethylisophthalophenone,
3,3',4,4'-tetra(t-butylperoxycarbonyl)benzophenone, and
4,4'-diethylaminobenzophenone can be used in
10 combination.
The sensitizer can be incorporated in an amount of
from 0.1 parts by mass to 60 parts by mass relative to
100 parts by mass of the photopolymerization initiator.
(Ethylenically unsaturated compound)
15 The photopolymerization initiator described above
is preferably used together with an ethylenically
unsaturated compound. An ethylenically unsaturated
compound means a compound having one or more
ethylenically unsaturated bonds in the molecule. Among
20 others, a compound having two or more ethylenically
unsaturated bonds in the molecule is preferred from the
viewpoints of polymerizability, crosslinkability, and
the consequent possibility to increase the difference
in the developing liquid solubility between an exposed
25 area and a non-exposed area. Furthermore, a
(meth)acrylate compound in which the unsaturated bond
originates from a (meth)acryloyloxy group is
60
particularly preferred.
Examples of the compound having one or more
ethylenically unsaturated bonds in the molecule include
unsaturated carboxylic acids such as (meth)acrylic
5 acid, crotonic acid, isocrotonic acid, maleic acid,
itaconic acid and citraconic acid, and alkyl esters
thereof; (meth) acrylonitrile; (meth)acrylamide; and
styrene. Representative examples of the compound
having two or more ethylenically unsaturated bonds in
10 the molecule include esters between unsaturated
carboxylic acids and polyhydroxy compounds,
(meth)acryloyloxy group-containing phosphates, urethane
(meth)acrylates between hydroxyl (meth) acrylate
compounds and polyisocyanate compounds, and epoxy
15 (meth)acrylates between (meth)acrylic acid or
hydroxy(meth)acrylate compounds and polyepoxy
compounds.
The photopolymerizable initiator, sensitizer and
ethylenically unsaturated compound may be added to a
20 composition containing a polymerizable liquid crystal
compound used in the formation of a retardation layer
that will be described below.
(Polyfunctional thiol)
In the photosensitive color composition, a
25 polyfunctional thiol that functions as a chain transfer
agent can be incorporated. The polyfunctional thiol
may be a compound having two or more thiol groups, and
61
examples thereof include hexanedithiol, decanedithiol,
1,4-butanediol bisthiopropionate, 1,4-butanediol
bisthioglycolate, ethylene glycol bisthioglycolate,
ethylene glycol bisthiopropionate, trimethylolpropane
5 tristhioglycolate, trimethylolpropane
tristhiopropionate, trimethylolpropane tris(3mercaptobutyrate),
pentaerythritol
tetrakisthioglycolate, pentaerythritol
tetrakisthiopropionate, trimercaptopropionic acid
10 tris (2-hydroxyethyl) isocyanurate, 1,4dimethylmercaptobenzene,
2,4,6-trimercapto-s-triazine,
and 2-(N,N-dibutylamino)-4,6-dimercapto-s-triazine.
Such polyfunctional thiols can be used singly or
as mixtures of two or more kinds. The polyfunctional
15 thiol can be used in an amount of preferably 0.2 parts
to 150 parts by mass, and more preferably 0.2 parts to
100 parts by mass, relative to 100 parts by mass of the
pigment.
(Storage stabilizer)
20 In the photosensitive color composition, a storage
stabilizer can be incorporated in order to stabilize
the viscosity of the composition over time. Examples
of the storage stabilizer include benzyltrimethyl
chloride; quaternary ammonium chlorides such as
25 diethylhydroxyamine; organic acids such as lactic acid
and oxalic acid, and methyl ethers thereof; organic
phosphines such as t-butylpyrocatechol,
62
triethylphosphine, and triphenylphosphine; and
phosphorous acid salts.
(Adhesion enhancing agent)
In the photosensitive color composition, an
5 adhesion enhancing agent such as a silane coupling
agent can be incorporated in order to increase the
adhesiveness to a substrate.
(Solvent)
In the photosensitive color composition, a solvent
10 such as water or an organic solvent is incorporated in
order to enable uniform application on a substrate.
Furthermore, when the composition used in the present
embodiment is a color layer of a color filter, the
solvent also has a function of uniformly dispersing the
15 pigment. Examples of the solvent include
cyclohexanone, ethylcellosolve acetate, butylcellosolve
acetate, 1-methoxy-2-propyl acetate, diethylene glycol
dimethyl ether, ethylbenzene, ethylene glycol diethyl
ether, xylene, ethylcellosolve, methyl n-amyl ketone,
20 propylene glycol monomethyl ether, toluene, methyl
ethyl ketone, ethyl acetate, methanol, ethanol,
isopropyl alcohol, butanol, isobutyl ketone, and
petroleum-based solvents. These can be used singly or
as mixtures. The solvent can be incorporated in an
25 amount of from 800 parts to 4000 parts by mass, and
preferably from 1000 parts to 2500 parts, relative to
100 parts by mass of the pigment.
63
(Organic pigment)
Examples of red pigments that can be used include
C.l. Pigment Red 7, 9, 14, 41, 48:1, 48:2, 48:3, 48:4,
81:1, 81:2, 81:3, 97, 122, 123, 146, 149, 168, 177,
5 178, 179, 180, 184, 185, 187, 192, 200, 202, 208, 210,
215, 216, 217, 220, 223, 224, 226, 227, 228, 240, 242,
246, 254, 255, 264, 272, and 279.
Examples of yellow pigments include C.l. Pigment
Yellow 1, 2, 3, 4, 5, 6, 10, 12, 13, 14, 15, 16, 17,
10 18, 20, 24, 31, 32, 34, 35, 35:1, 36, 36:1, 37, 37:1,
40, 42, 43, 53, 55, 60, 61, 62, 63, 65, 73, 74, 77, 81,
83, 86, 93, 94, 95, 97, 98, 100, 101, 104, 106, 108,
109, 110, 113, 114, 115, 116, 117, 118, 119, 120, 123,
125, 126, 127, 128, 129, 137, 138, 139, 144, 146, 147,
15 148, 150, 151, 152, 153, 154, 155, 156, 161, 162, 164,
166, 167, 168, 169, 170, 171, 172, 173, 174, 175, 176,
177, 179, 180, 181, 182, 185, 187, 188, 193, 194, 199,
213, and 214.
Examples of blue pigments that can be used include
20 C.l. Pigment Blue 15, 15:1, 15:2, 15:3, 15:4, 15:6, 16,
22, 60, 64, and 80, and among these, C.l. Pigment Blue
15:6 is preferred.
Examples of violet pigments that can be used
include C.l. Pigment Violet 1, 19, 23, 27, 29, 30, 32,
25 37, 40, 42, and 50, and among these, C.l. Pigment
Violet 23 is preferred.
Examples of green pigments that can be used
64
include C.I. Pigment Green 1, 2, 4, 7, 8, 10, 13, 14,
15, 17, 18, 19, 26, 36, 45, 48, 50, 51, 54, 55, and 58,
and among these, C.I. Pigment Green 58 which is a
halogenated zinc phthalocyanine green pigment is
5 preferred.
Hereinafter, in regard to the description of
pigment kinds of the C.I. Pigments, the pigments may be
simply described in abbreviations such as PB (Pigment
Blue), PV (Pigment Violet), PR (Pigment Red), PY
10 (Pigment Yellow), and PG (Pigment Green) .
(Coloring material of light shielding layer)
The light shielding coloring material that is
included in the light shielding layer or the black
matrix is a coloring material which exhibits a light
15 shielding function by having absorption in the visible
light wavelength region. Examples of the light
shielding coloring material in the present embodiment
include organic pigments, inorganic pigments, and dyes.
Examples of the inorganic pigments include carbon black
20 and titanium oxide. Examples of the dyes include azobased
dyes, anthraquinone-based dyes, phthalocyaninebased
dyes, quinoneimine-based dyes, quinoline-based
dyes, nitro-based dyes, carbonyl-based dyes, and
methine-based dyes. In regard to the organic pigments,
25 those organic pigments described above can be employed.
Meanwhile, regarding the light shielding components,
one kind may be used, or two or more kinds may be used
65
together in any arbitrary combinations and ratios.
Furthermore, an increase in volume resistivity caused
by resin coating of the surfaces of these coloring
materials, or on the contrary, a decrease in volume
5 resistivity caused by imparting slight conductivity by
increasing the content ratio of the coloring material
with respect to the parent material of the resin, may
be carried out. However, since the volume resistivity
value of such a light shielding material is
10 approximately in the range of 1 x 10 8 to 1 x 10 1 5 Q·cm,
the volume resistivity value is not at a level of
affecting the resistivity value of the transparent
conductive film. Similarly, the relative permittivity
of the light shielding layer can also be adjusted to
15 the range of 3 to 11 by means of the selection or
content ratio of the coloring material. The relative
permittivities of the light shielding layer, the first
transparent resin layer, and the color layer can be
adjusted according to the design conditions for the
20 liquid crystal display device, or the conditions for
driving the liquid crystals.
(Dispersant/dispersion aid)
When a polymer dispersant is used as a pigment
dispersant, it is preferable because dispersion
25 stability over time is excellent. Examples of the
polymer dispersant include a urethane-based dispersant,
a polyethyleneimine-based dispersant, a polyoxyethylene
66
alkyl ether-based dispersant, a polyoxyethylene glycol
diester-based dispersant, a sorbitan aliphatic esterbased
dispersant, and an aliphatic-modified polyesterbased
dispersant. Among them, particularly, a
5 dispersant formed from a graft copolymer containing
nitrogen atoms is preferred for the light shielding
photosensitive resin composition used in the present
embodiment containing a large amount of a pigment, from
the viewpoint of developability.
10 Specific examples of these dispersants include, as
listed under product names, EFKA (manufactured by EFKA
BV), DISPERBYK (manufactured by BYK Chemie GmbH),
DISPARLON (manufactured by Kusumoto Chemicals, Ltd.),
SOLSPERSE (manufactured by Lubrizol, Inc.), KP
15 (manufactured by Shin-Etsu Chemical Co., Ltd.), and
POLY FLOW (manufactured by Kyoeisha Chemical Co., Ltd.).
These dispersants may be used singly, or two or more
kinds can be used together in arbitrary combinations
and ratios.
20 Regarding a dispersion aid, for example, a
colorant derivative and the like can be used. Examples
of the colorant derivative include azo-based,
phthalocyanine-based, quinacridone-based,
benzimidazolone-based, quinophthalone-based,
25 isoindolinone-based, dioxazine-based, anthraquinonebased,
indanthrene-based, perylene-based, perinonebased,
diketopyrrolopyrrole-based, and dioxazine-based
67
derivatives, but among these, quinophthalone-based
colorant derivatives are preferred.
Regarding the substituent of the colorant
derivative, for example, a sulfonic acid group, a
5 sulfonamide group and quaternary salts thereof, a
phthalimidomethyl group, a dialkylaminoalkyl group, a
hydroxyl group, a carboxyl group, an amide group and
the like being bonded to the pigment skeleton directly
or through an alkyl group, an aryl group, a
10 heterocyclic group or the like, may be used. Among
these, a sulfonic acid group is preferred. Regarding
these substituents, plural substituents may be
substituted in one pigment skeleton.
Specific examples of the colorant derivative
15 include sulfonic acid derivatives of phthalocyanine,
sulfonic acid derivatives of quinophthalone, sulfonic
acid derivatives of anthraquinone, sulfonic acid
derivatives of quinacridone, sulfonic acid derivatives
of diketopyrrolopyrrole, and sulfonic acid derivatives
20 of dioxazine.
The dispersion aids and colorant derivatives
described above may be used singly, or two or more
kinds may be used together in any arbitrary
combinations and ratios.
25 Hereinafter, various Examples of the present
invention will be described.
68
[Example 1]
A color filter substrate 10 as illustrated in
FIG. 1 was produced in the following manner.
[Formation of black matrix]
5 (Black matrix-forming dispersion liquid)
20 parts by mass of carbon pigment #47
(manufactured by Mitsubishi Chemical Corp.), 8.3 parts
by mass of polymer dispersant BYK-182 (manufactured by
BYK Chemie GmbH), 1.0 part by mass of a copper
10 phthalocyanine derivative (manufactured by Toyo Ink
Manufacturing Co., Ltd.), and 71 parts by mass of
propylene glycol monomethyl ether acetate were stirred
in a bead mill dispersing machine, and thus a carbon
black dispersion liquid was prepared.
15 (Black matrix-forming photoresist)
As a material for the liquid shielding layer, a
black matrix-forming resist 1 was prepared by using the
following materials.
Carbon black dispersion liquid: Pigment #47
20 (manufactured by Mitsubishi Chemical Corp.)
Transparent resin: V259-ME (manufactured by Nippon
Steel Chemical Co., Ltd.) (solids content: 56.1% by
mass)
Photopolymerizable monomer: DPHA (manufactured by
25 Nippon Kayaku Co., Ltd.)
Initiator: OXE-02 (manufactured by Ciba Specialty
Chemicals Corp.)
69
OXE-01 (manufactured by Ciba Specialty
Chemicals Corp.)
Solvent: Propylene glycol monomethyl ether acetate
Ethyl 3-ethoxypropionate
5 Leveling agent: BYK-330 (manufactured by BYK
Chemie GmbH)
The above materials were mixed and stirred at the
following composition ratio, and thus a black matrixforming
resist 1 (pigment concentration in the solids
10 content: about 20%) was obtained.
Carbon black dispersion liquid
3.0 parts by mass
Transparent resin 1.4 parts by mass
Photopolymerizable monomer 0.4 parts by mass
15 Photopolymerization initiator OXE-01
0.67 parts by mass
Photopolymerization initiator OXE-02
0.17 parts by mass
Propylene glycol monomethyl ether acetate
20 14 parts by mass
Ethyl 3-ethoxypropionate 5.0 parts by mass
Leveling agent 1.5 parts by mass
(Conditions for forming black matrix)
The black matrix-forming resist 1 was spin coated
25 on a transparent substrate 1 which was an alkali-free
glass plate, and the resist was dried. Thus, a coating
film having a film thickness of 1.5 pm was produced.
70
Such a coating film was dried for 3 minutes at 100°C,
and then was irradiated at a dose of 200 mJ/cm2 by
using a photomask for exposure having openings with a
pattern width of the black matrix (corresponding to the
5 image line width of the black matrix) of 24.5 pm, and
using an ultrahigh pressure mercury lamp as a light
source.
Next, the pattern was developed with a 2.5%
aqueous solution of sodium carbonate for 60 seconds,
10 and after development, the pattern was thoroughly
washed with water and was further dried. Subsequently,
the pattern was heat treated for 60 minutes at 230°C to
cure, and thus a black matrix 5 was formed. The image
line width of the black matrix 5 was about 24 pm, and
15 the image lines were formed along the periphery of a
rectangular pixel (four sides). The angle of
inclination of an edge of the black matrix image line
from the surface of the transparent conductive film was
adjusted to about 45 degrees.
20 (Formation of transparent conductive film)
Subsequently, a transparent conductive film 3
(third electrode) formed from ITO (a metal oxide thin
film of indium and tin) was formed to have a film
thickness of 0.14 pm by using a sputtering apparatus.
25 [Formation of second transparent resin layer]
(Synthesis of resin A)
In a separable flask, 686 parts by mass of
71
propylene glycol monomethyl ether acetate, 332 parts
by mass of glycidyl methacrylate, and 6.6 parts by
mass of azobisisobutyronitrile were introduced, and
the mixture was heated for 6 hours at 80°C in a
5 nitrogen atmosphere. Thus, a resin solution was
obtained.
Next, 168 parts by mass of acrylic acid, 0.05
parts by mass of methoquinone, and 0.5 parts by mass of
triphenylphosphine were added to the resin solution
10 thus obtained, and the mixture was heated for 24 hours
at 100°C while air was blown. Thus, an acrylic acidadded
resin solution was obtained.
Furthermore, 186 parts by mass of
tetrahydrophthalic anhydride was added to the acrylic
15 acid-added resin solution thus obtained, and the
mixture was heated for 10 hours at 70°C. Thus, a resin
A solution was obtained.
(Preparation of photosensitive resin liquid A)
A negative type photosensitive resin liquid A at
20 the following composition was prepared.
Resin A 200 parts by mass
Photopolymerizable monomer
Dipentaerythritol hexaacrylate
20 parts by mass
25 Photopolymerization initiator
(manufactured by Ciba Specialty Chemicals
Corp., IRGACURE 907) 10 parts by mass
72
Solvent (propylene glycol monomethyl ether
acetate) 280 parts by mass
A second transparent resin layer 8 was formed by a
known photolithographic technique, by using the
5 photosensitive resin solution A, and a photomask having
the pattern (openings) of the second transparent resin
layer. The film thickness of the second transparent
resin layer 8 was adjusted to 1.3 ~m, and the second
transparent resin layer 8 was formed to have a line
10 width of 20 ~m, at the center of the pixel and along
the longitudinal direction of the opening of the black
matrix.
[Formation of color pixel]
«Color layer-forming dispersion liquid»
15 As the organic pigments that were dispersed in the
color layers, the following pigments were used.
Pigment for red: C.I. Pigment Red 254 ("IRGA FOR
RED B-CF" manufactured by Ciba Specialty Chemicals
Corp.), C.I. Pigment Red 177 ("CHROMOPHTAL RED A2B"
20 manufactured by Ciba Specialty Chemicals Corp.)
Pigment for green: C.I. Pigment Green 58
(manufactured by DIC, Inc.), C.I. Pigment Yellow 150
("FANCHON FAST YELLOW Y-5688" manufactured by Bayer AG)
Pigment for blue: C.I. Pigment Blue 15 ("LIANOL
25 BLUE ES" manufactured by Toyo Ink Manufacturing Co.,
Ltd. )
C.I. Pigment Violet 23
73
("VARIOGEN VIOLET 5890" manufactured by BASF SE)
Dispersion liquids for the respective colors of
red, green and blue were prepared by using the pigments
described above.
5
Red pigment: C.I. Pigment Red 254
18 parts by mass
Red pigment: C.I. Pigment Red 177
2 parts by mass
10 Acrylic varnish (solid content: 20% by mass)
108 parts by mass
The mixture of the foregoing composition was
uniformly stirred, subsequently dispersed with a sand
mill for 5 hours by using glass beads, and filtered
15 through a 5-~m filter. Thus, a red pigment dispersion
liquid was prepared.

Green pigment: C.I. Pigment Green 58
16 parts by mass
20 Green pigment: C.I. Pigment Yellow 150
8 parts by mass
Acrylic varnish (solids content: 20% by mass)
102 parts by mass
A green pigment dispersion liquid was prepared
25 from the mixture of the foregoing composition, by using
the same preparation method as that used for the red
pigment dispersion liquid.
74

Blue pigment: C.l. Pigment Blue 15
50 parts by mass
Blue pigment: C.l. Pigment Violet 23
5 2 parts by mass
Dispersant ("SOLSPERSE 20000" manufactured by
Zeneca Group PLC) 6 parts by mass
Acrylic varnish (solids content: 20% by mass)
200 parts by mass
10 A blue pigment dispersion liquid was prepared from
the mixture of the foregoing composition, by using the
same preparation method as that used for the red
pigment dispersion liquid.
«Formation of color pixels»
15 Color layers were formed by using color resists
for forming color pixels of the mixing compositions
indicated in the following Table 1.
e
Table 1
Color resist For red pixels For green pixels For blue pixels
Pigment dispersion liquid Red dispersion liquid Green dispersion liquid Blue dispersion liquid
______________ ~~_~~ _J?~~~~) ______________ 42.5 43.5 35 ----------------------------------- -------------------------------------- ------------------------------------
Acrylic resin solution 6.7 5.7 14.2
Monomer 4.0 4.8 5.6
Photopolymerization initiator 3.4 2.8 2.0
Sensitizer 0.4 0.2 0.2
Organic solvent 43.0 43.0 43.0
Total 100 100 100
--..I
U1
~-------~---~-~ " '""- -GLL__""._" LSO _U_A- -" S __
76
In regard to the formation of color layers, first,
as illustrated in FIG. 1, a color resist for forming
red pixels was applied by spin coating on the substrate
1 having the black matrix 5, the transparent conductive
5 film 3, and the second transparent resin layer 8 formed
thereon, such that the finished film thickness would be
2.5 ~m. The color resist was dried for 5 minutes at
90°C, and then was irradiated through a photomask for
forming color pixels with the light of a high pressure
10 mercury lamp at an exposure dose of 300 mJ/cm2. The
color resist was developed for 60 seconds with an
alkali developing liquid, and thus stripe-shaped color
pixels 15 of red were formed on the pixel region so as
to overlap with the second transparent resin layer 8.
15 Thereafter, the color resist was baked at 230°C for
30 minutes.
Meanwhile, as the photomask, a photomask provided
with half-tone sections at the positions corresponding
to the second transparent resin layer 8 was used, such
20 that the film thickness of the thin color layer on the
second transparent resin layer 8 would become
approximately 1.3 pm after exposure and development,
and the entire pixel would become roughly flat after
film curing. For the photomasks for forming green
25 pixels and blue pixels as described below, similarly,
photomasks provided with half-tone sections in the
midsection of the pixels.
77
Next, the resist for forming green pixels was also
applied by spin coating in the same manner such that
the finished film thickness would be 2.5 ~m, and the
resist for forming green pixels would cover the second
5 transparent resin layer 8. The resist was dried for
5 minutes at 90°C, and then was exposed through a
photomask and developed so that a pattern would be
formed at positions adjacent to the red pixels 15.
Thus, green pixels 14 were formed. Meanwhile, the
10 production of the color filter substrate, including the
present Example, was carried out by using a well known
photolithographic technology.
Furthermore, a resist for forming blue pixels was
also completed in the same manner as in the case of red
15 and green pixels, and blue pixels 16 having a film
thickness of 2.5 ~m and positioned adjacent to the red
pixels and the green pixels were obtained. Thereby,
color pixels of three colors, namely, red, green and
blue, were formed on the substrate 1. Thereafter, the
20 assembly was subjected to a heat treatment at 230°C for
30 minutes to cure the films.
[Formation of first transparent resin layer]
(Synthesis of resin B)
In a l-liter five-necked flask, 75 g of n-butyl
25 methacrylate, 30 g of methacrylic acid, 25 g of 2hydroxyethyl
methacrylate, and 300 g of propylene
glycol monomethyl ether acetate were introduced, and
78
2 g of AIBN was added thereto in a nitrogen atmosphere.
The mixture was allowed to react for 8 hours at 80°C to
85°C. Furthermore, the reaction mixture was prepared
with propylene glycol monomethyl ether acetate so that
5 the non-volatile component fraction of this resin would
be 20% by mass, and thus a solution of resin B (alkalisoluble
resin B) was obtained.
(Resin coating liquid B)
The following material was prepared as a resin
10 coating liquid B for forming the first transparent
resin layer.
32 g of cyclohexanone and 38 g of diethylene
glycol dimethyl ether were introduced into a sample
bottle. While the content was stirred, 13 g of an
15 epoxy resin: ESF-300 (manufactured by Nippon Steel
Chemical Co., Ltd.), 7 g of an alicyclic polyfunctional
epoxy resin: EHPE3150 (manufactured by Daicel Chemical
Industries, Ltd.), and 5 g of an alicyclic epoxy resin:
CELLOXIDE 2021P (manufactured by Daicel Chemical
20 Industries, Ltd.) were added to the sample bottle, and
the mixture was completely dissolved. Subsequently,
3.0 g of an acid anhydride: trimellitic anhydride was
added thereto, and the mixture was sufficiently stirred
and dissolved. Subsequently, 1.2 g of a silane
25 coupling agent (S-510 manufactured by Chisso Corp.) and
0.11 g of a surfactant (FLUORAD FC-430 manufactured by
Sumitomo 3M, Ltd.) were added thereto, and the
79
resulting mixture was sufficiently stirred. This was
filtered, and thus a resin coating liquid B was
obtained.
The resin coating liquid B was applied on the
5 color layers 14, 15 and 16, and the assembly was
prebaked for 120 seconds at 90°C. The resin coating
liquid B was exposed at predetermined areas, developed,
and baked for 30 minutes at 230°C, and thereby, a first
transparent resin layer 7 was formed. Thus, a color
10 filter substrate 10 was obtained.
The height H of the color layer overlapping
section 6, which was an overlapping section of the
black matrix 5, transparent conductive film 3, color
layers 14, 15 and 16, and the first transparent resin
15 layer 7, was adjusted to 0.7 ~m as a difference from
the surface of the first transparent resin layer 8
within the pixel. The areas of the transparent
conductive film 3 arranged on the black matrix 5 in the
present Example can shorten the inter-electrode
20 distance from the first electrode, which is a pixel
electrode when used in a liquid crystal display device,
and therefore, there is an advantage that the movement
of the liquid crystals present between these electrodes
can be made faster.
25 [Example 2]
In the present Example, a color filter substrate
10 shown in FIG. 2 was produced. The color filer
80
substrate 10 according to the present Example has a
configuration in which, as illustrated in FIG. 2, the
order of formation of the black matrix 5 and the
transparent conductive film 3 is changed, and the
5 materials used herein and the technology related to the
process are the same as in Example 1.
At the color layer overlapping section 6 of
Example 2, as the black matrix 5 is arranged on the
transparent conductive film 3, the inter-electrode
10 distance from the first electrode, which is a pixel
electrode when used in a liquid crystal display device,
becomes larger as compared with Example 1. However,
since the black matrix 5 uses carbon having a high
relative permittivity as a coloring agent for the light
15 shielding layer, a decrease in the voltage can be
complemented.
[Example 3]
In the present Example, a color filter substrate
10 illustrated in FIG. 3 was produced.
20 As illustrated in FIG. 3, a transparent conductive
film 3 (third electrode) formed from ITO (a metal oxide
thin film of indium and tin) was formed to have a film
thickness of 0.14 ~m in an amorphous state at room
temperature, on a transparent substrate 1 which was an
25 alkali-free glass plate, by using a sputtering
apparatus. The amorphous ITO film formed at room
temperature can easily form a fine pattern.
81
Subsequently, slits 18 each having a width of 8 pm
were formed in the ITO film by a known
photolithographic technique, by using a photomask
having a line-shaped light shielding pattern having a
5 line width of 9 pm in the longitudinal direction at the
center of the pixels. The slit 18 is a pattern of
opening where an ITO film is not formed. Meanwhile,
the slits in the ITO film can also be formed by direct
processing using a laser light of high intensity.
10 Next, a black matrix 5 was formed by using the
black matrix-forming resist 2 described below, and
subsequently, color layers 14, 15 and 16 were formed by
using the color resists described below. A first
transparent resin layer 7 was further formed by using
15 the same material as that used in Example 1, and thus
the color filter substrate 10 illustrated in FIG. 3 was
obtained.
[Preparation of carbon black dispersion liquid]
A mixture of the composition described below
20 was uniformly stirred and mixed, and then the
mixture was stirred with a bead mill dispersing
machine. Thus, a carbon black dispersion liquid was
prepared.
Carbon pigment (#47 manufactured by Mitsubishi
25 Chemical Corp.) 20 parts
Dispersant 8.3 parts
82
("DISPERBYK-161 manufactured by BYK Chemie GmbH)
Copper phthalocyanine derivative (manufactured by
Toyo Ink Manufacturing Co., Ltd.) 1.0 part
Propylene glycol monomethyl ether acetate
5 71 parts
[Preparation of black matrix-forming resist 2]
A mixture of the composition described below was
stirred and mixed to be uniform, and then the mixture
was filtered through a filter having a pore size of
10 5 ~m. Thus, a black matrix-forming resist 2 was
obtained.
Carbon black dispersion liquid 25.2 parts
Acrylic resin solution 18 parts
Dipentaerythritol penta- and hexa-acrylate
15 ("M-4 02 II manufactured by Toagosei Co., Ltd.)
5.2 parts
Photopolymerization initiator 1.2 parts
("IRGACURE aXE 02" manufactured by Ciba Geigy
Corp. )
20 Sensitizer 0.3 parts
("EAB-F" manufactured by Hodogaya Chemical Co.,
Ltd. )
25
Leveling agent 0.1 parts
("DISPERBYK-163" manufactured by BYK Chemie GmbH)
Cyclohexanone 25 parts
Propylene glycol monomethyl ether acetate
25 parts
83
The compositions of the respective dispersion
liquids for the resists for forming red pixels, green
pixels and blue pixels and the color resists used in
the present Example will be described below.
5 [Preparation of red pigment 2]
A dispersion of the red pigment 2 was prepared by
the same method as that used for the red pigment 1, by
using a mixture of the composition described below.
Red pigment: C.I. Pigment Red 254 11 parts
10 (" IRGA FOR RED B-CF" manufactured by Ciba
Specialty Chemicals Corp.)
Red pigment: C.I. Pigment Red 177 9 parts
("CHROMOPHTAL RED A2B" manufactured by Ciba
Specialty Chemicals Corp.)
15 Dispersant ("AJISPER PB821" manufactured by
Ajinomoto Fine-Techno Co., Inc.) 2 parts
Acrylic varnish (solids content: 20% by mass)
108 parts
[Preparation of red composition 2]
20 Thereafter, a mixture of the composition described
below was stirred and mixed so as to be uniform, and
then the mixture was filtered through a filter having a
pore size of 5 pm. Thus, a red composition was
obtained.
25 Red pigment 2
Acrylic resin solution
42 parts
18 parts
84
Dipentaerythritol penta- and hexa-acrylate
4.5 parts
("M-402" manufactured by Toagosei Co., Ltd.)
Photopolymerization initiator 1.2 parts
5 ("IRGACURE 907" manufactured by Ciba Specialty
Chemicals Corp.)
Sensitizer ("EAB-F" manufactured by Hodogaya
Chemical Co., Ltd.) 2.0 parts
Cyclohexanone 32.3 parts
10 [Preparation of green pigment 2]
A dispersion of the green pigment 2 was prepared
by the same method as that used for the green pigment
1, by using a mixture of the composition described
below.
15 Green pigment: C.I. Pigment Green 58
("Phthalocyanine Green A1 lO" manufactured by Dainippon
Ink & Chemicals, Inc.) 10.4 parts
Yellow pigment: C.I. Pigment Yellow 150 ("E4GN-GT"
manufactured by Lanxess AG) 3.2 parts
20 Yellow pigment: C.I. Pigment Yellow 138
7.4 parts
Dispersant ("DISPERBYK-163" manufactured by BYK
Chemie GmbH) 2 parts
Acrylic varnish (solids content: 20% by mass)
25 66 parts
[Preparation of green composition 2]
Thereafter, a mixture of the composition described
85
below was stirred and mixed so as to be uniform, and
then the mixture was filtered through a filter having a
pore size of 5 ~m. Thus, a red composition was
obtained.
5 Green pigment 2 46 parts
Acrylic resin solution 8 parts
Dipentaerythritol penta- and hexa-acrylate ("M-
402" manufactured by Toagosei Co., Ltd.) 4 parts
Photopolymerization initiator ("lRGACURE aXE 02"
10 manufactured by Ciba Geigy Corp.) 1.2 parts
Photopolymerization initiator ("lRGACURE 907"
manufactured by Ciba Specialty Chemicals Corp.)
3.5 parts
Sensitizer ("EAB-F" manufactured by Hodogaya
15 Chemical Co., Ltd.) 1.5 parts
Cyclohexanone 5.8 parts
Propylene glycol monomethyl ether acetate
30 parts
[Preparation of blue pigment 2]
20 A mixture of the composition described below was
uniformly stirred and mixed, and then the mixture was
dispersed with a sand mill for 5 hours by using glass
beads having a diameter of 1 mm. Subsequently, the
dispersion was filtered through a filter having a pore
25 size of 5 ~m, and thus a dispersion of a blue pigment
was prepared.
Blue pigment: C.l. Pigment Blue 15:6
86
("LIONOL BLUE ES" manufactured by Toyo Ink
Manufacturing Co., Ltd.) 49.4 parts
Dispersant ("S0LSPERSE 20000" manufactured by
Zeneca Group PLC) 6 parts
5 Acrylic varnish (solids content: 20% by mass)
200 parts
The violet dye powder described below was added to
this dispersion, and the mixture was thoroughly
stirred. Thus, a blue pigment 2 was obtained.
10 Violet dye: NK-9402 (manufactured by Hayashibara
Biochemical Laboratories, Inc.) 2.6 parts
[Preparation of blue composition 2]
Thereafter, a mixture of the composition described
below was stirred and mixed so as to be uniform, and
15 then the mixture was filtered through a filter having a
pore size of 5 pm. Thus, a blue composition was
obtained.
Blue pigment 2 16.5 parts
Acrylic resin solution 25.3 parts
20 Dipentaerythritol penta- and hexa-acrylate ("M-
402" manufactured by Toagosei Co., Ltd.) 1.8 parts
Photopolymerization initiator 1.2 parts
("IRGACURE 907" manufactured by Ciba Specialty
Chemicals Corp.)
25 Sensitizer ("EAB-F" manufactured by Hodogaya
Chemical Co., Ltd.) 0.2 parts
Cyclohexanone 25 parts
87
Propylene glycol monomethyl ether acetate
30 parts
[Relative permittivities of coating films of
various colors]
5 Each of the color resists used in Example 3 and
Example 1 was processed into a sample for measuring the
relative permittivity (the film thickness of the color
coating film was adjusted to 2.8 pm), and the relative
permittivity was measured by using an impedance
10 analyzer.
The values of relative permittivity together with
the values of measurement frequency are presented in
the following Table 2.
Table 2
Example 1 Example 3
Red Green Blue Red Green Blue Light
Measurement
frequency
layer layer layer layer layer layer shielding layer
(R) (G) (B) (R) (G) (B) (BM)
120 Hz 3.6 3.8 3.6 3.2 3.5 3.1 16.2
Relative
240 Hz 3.5 3.7 3.6 3.2 3.4 3 16.1
permittivity
480 Hz 3.5 3.7 3.6 3.2 3.4 3 15.5
co
co
fJ
89
For the pigment of the green resist used in
Example 1, Example 2 and Example 3, a halogenated zinc
phthalocyanine green pigment (number of bromination:
14.1) was used. Meanwhile, the relative permittivity
5 of a green layer obtained by substituting this pigment
with a halogenated copper phthalocyanine green pigment
that has been traditionally used is 4.5, which is
higher by 0.9 than the relative permittivity of the red
layer indicated in the Table 1. Thus, there may be a
10 hindrance in arranging red pixels, green pixels and
blue pixels on the third electrode and achieving a
uniform color display. When a green pixel having a
relative permittivity of 4.5 is used, the electric
field is different from the electric field in which the
15 liquid crystal layers of the red pixel and the blue
pixel and the liquid crystal layer of the green pixel
are different. Therefore, a shift of subtle gradation
tends to easily occur at the same liquid crystal
driving voltage. As described above, it is preferable
20 to adjust the difference in the relative permittivity
of different color pixels to to.3 or less with respect
to the average relative permittivity of those pixels.
As discussed above, since the color filter
substrate according to the present Example is equipped
25 with color layers having uniform relative
permittivities for various colors and low relative
permittivities on a transparent conductive film which
90
is a third electrode, a uniform electric field can be
formed between the first electrode and the third
electrode, and the liquid crystal display quality can
be enhanced.
5 The configuration in which the black matrix is
formed on the third electrode is preferable from the
viewpoint that since the relative permittivity is high,
it is easy to apply a voltage to the liquid crystal
molecules that are located at the shoulder of the color
10 layer overlapping section 6. The configuration in
which the third electrode is laminated on the black
matrix as shown in Example 1 is preferable from the
viewpoint that the configuration exerts a stronger
effect on the liquid crystal molecules located at the
15 shoulder.
[Example 4]
In the present Example, the color filter substrate
10 illustrated in FIG. 4 was produced as follows.
On a transparent substrate 1 which was an alkali-
20 free glass plate, the black matrix-forming resist used
in Example 1 was spin coated and dried, and thus a
coating film having a film thickness of 1.5 pm was
produced. Such a coating film was dried for 3 minutes
at 100 o e, and then the coating film was irradiated at a
25 dose of 200 mJ/cm2 by using a photomask for exposure
having a pattern width of the black matrix
(corresponding to the image line width of the black
91
matrix) of 24.5 ~m and having openings, and by using an
ultrahigh pressure mercury lamp as a light source.
After development, the color filter substrate was
thoroughly washed with water, further dried, and then
5 heat treated for 60 minutes at 230°C to cure the
pattern. Thus, the black matrix 5 was formed on the
transparent substrate. Meanwhile, the shape of the
opening of the black matrix was made into a polygon
having the shape of "symbol <" as shown in FIG. 20B,
10 the image line width of the black matrix 5 was about
24 ~m, and the black matrix was formed in the periphery
of the openings of the polygonal pixels.
Next, a transparent conductive film 3 (third
electrode) formed from ITO (a metal oxide thin film of
15 indium and tin) was formed to have a film thickness of
0.14 ~m in an amorphous state at room temperature, on
the substrate 1 having the black matrix 5 formed
thereon, by using a sputtering apparatus. The
amorphous ITO film formed at room temperature has an
20 advantage that a fine pattern can be easily formed.
Next, a slit 18 having the shape of "symbol <" and
having a width of 8 ~m was formed in the ITO film by a
known photolithographic technique, by using a photomask
provided with a linear light shielding pattern having
25 the shape of "symbol <" with a width of 9 ~m at the
center of the pixel in the longitudinal direction. The
slit 18 is an opening pattern where an ITO film is not
92
formed.
Next, a pattern having the shape of "symbol <" was
formed at a film thickness of 2.8 ~m at each of the
polygon-shaped openings of the black matrix 5 by a
5 known photolithographic technique by using the red
resist, green resist and blue resist used in Example 3.
Furthermore, a first transparent resin layer 7
having a film thickness of 0.7 ~m was formed, and thus
a color filter substrate 10 was obtained.
10 [Example 5]
In the present Example, a color filter substrate
10 illustrated in FIG. 5 was produced as follows.
On a transparent substrate 1 which was an alkalifree
glass plate, the black matrix-forming resist used
15 in Example 1 was spin coated and dried, and thus a
coating film having a film thickness of 1.5 ~m was
produced. Such a coating film was dried for 3 minutes
at 100°C, and then the coating film was irradiated at a
dose of 200 mJ/cm2 by using a photomask for exposure
20 having a pattern width of the black matrix
(corresponding to the image line width of the black
matrix) of 24.5 ~m and having openings, and by using an
ultrahigh pressure mercury lamp as a light source.
After development, the color filter substrate was
25 thoroughly washed with water, further dried, and then
heat treated for 60 minutes at 230°C to cure the
pattern. Thus, the black matrix 5 was formed on the
93
transparent substrate. Meanwhile, the shape of the
opening of the black matrix was made into a polygon
having the shape of "symbol <" as shown in FIG. 20B,
the image line width of the black matrix 5 was about
5 24 pm, and the black matrix was formed in the periphery
of the openings of the polygonal pixels.
Next, a transparent conductive film 3 (third
electrode) formed from ITO (a metal oxide thin film of
indium and tin) was formed to have a film thickness of
10 0.14 pm in an amorphous state at room temperature, on
the substrate 1 having the black matrix 5 formed
thereon, by using a sputtering apparatus. The
amorphous ITO film formed at room temperature has an
advantage that a fine pattern can be easily formed.
15 Next, a slit 18 having the shape of "symbol <" and
having a width of 8 pm was formed in the ITO film by a
known photolithographic technique, by using a photomask
provided with a linear light shielding pattern having
the shape of "symbol <" with a width of 9 pm at the
20 center of the pixel in the longitudinal direction. The
slit 18 is an opening pattern where an ITO film is not
formed.
Next, a second transparent resin layer 8 was
formed by a known photolithographic technique by using
25 a photosensitive resin solution A and using a photomask
having the pattern (openings) of the "symbol <" shape
of the second transparent resin layer. The film
94
thickness of the second transparent resin layer 8 was
adjusted to 1.3 pm, and the second transparent resin
layer was formed in the midsection of the pixel with a
line width of 20 pm and at the center of the black
5 matrix opening in the longitudinal direction.
Next, a pattern having the shape of "symbol <" was
formed at a film thickness of 2.8 pm at each of the
polygon-shaped openings of the black matrix 5 by a
known photolithographic technique by using the red
10 resist, green resist and blue resist used in Example 3.
Furthermore, a first transparent resin layer 7
having a film thickness of 0.7 pm was formed, and thus
a color filter substrate was obtained.
[Example 6]
15 In the present Example, a liquid crystal display
device as illustrated in FIG. 6 was produced as
follows.
As illustrated in FIG. 6, the color filter
substrate 10 according to Example 5 and an array
20 substrate 20 having an active element such as TFT
formed thereon were sealed together, and a liquid
crystal 17 having negative dielectric constant
anisotropy was encapsulated therebetween. A polarizing
plate (not shown in the diagram) was sealed to each of
25 the two surfaces of the assembly, and thus a liquid
crystal display device was obtained. On the sides
where the color filter substrate 10 and the array
95
substrate 20 were in contact with the liquid crystals
17, a vertically aligned film had been applied in
advance to be formed. Meanwhile, in the array
5
substrate 20 where an active element was formed, combshaped
electrodes 1 and 2 in the form of "symbol <" as
illustrated in FIG. 20B were formed.
In addition, the alignment film for vertical
orientation is not shown in the diagram. A strict
15
orientation treatment (for example, an orientation
10 treatment in plural directions for forming plural
domains, with the tilt angle being set to 89°) that is
required in liquid crystal display devices of vertical
orientation, such as MVA or VATN, was not carried out,
and vertical orientation at almost 90° was achieved.
The first electrode 1 is electrically connected to
the active element (TFT) of the array substrate 20.
The second electrode and the third electrode served as
common electrode at a common potential (common). In
FIG. 6, the comb-shaped electrode 2c located below the
20 black matrix 5 in a planar view is also a common
electrode.
[Example 7]
In the present Example, a pixel arrangement in
which the pixel opening is parallelogram-shaped, as
25 illustrated in FIG. 23A, FIG. 23B and FIG. 23C, will be
described.
FIG. 23A illustrates an arrangement of color
96
pixels of three colors, namely, R, G and B, and
FIG. 23B and FIG. 23C illustrate the openings 25 of two
kinds of pixels having different angles of inclination.
The liquid crystals in these pixels are divided into
5 one-half pixel units which respectively have different
liquid crystal tilt directions 9. Furthermore, pixels
with different inclinations of the parallelograms, for
example, the directions in which four different liquid
crystal tilt directions as shown in FIG. 23B and
10 FIG. 23C, can be set, and thus, a liquid crystal
display device having a wide viewing angle can be
provided.
[Example 8]
In the present Example, a liquid crystal display
15 device illustrated in FIG. 12 was produced as follows.
As illustrated in FIG. 12, the color filter
substrate 10 according to Example 3 and an array
substrate 20 having an active element such as TFT
formed thereon were sealed together, and a liquid
20 crystal 17 having negative dielectric constant
anisotropy was encapsulated between the two substrates.
A polarizing plate was sealed to each of the two
surfaces of the assembly, and thus a liquid crystal
display device was obtained. On the surfaces of the
25 color filter substrate 10 and the array substrate 20, a
vertically aligned film had been applied in advance to
be formed. Meanwhile, in the array substrate 20 where
97
an active element was formed, comb-shaped electrodes 1
and 2 that were parallel to the long sides of the
rectangular opening shown in FIG. 218 were formed.
The alignment film for vertical orientation is not
5 shown in the diagram. A strict orientation treatment
(for example, an orientation treatment in plural
directions for forming plural domains, with the tilt
angle being set to 89°) that is required in liquid
crystal display devices of vertical orientation, such
10 as MVA or VATN, was not carried out, and vertical
orientation at almost 90° was achieved.
[Example 9]
In the present Example, a liquid crystal display
device illustrated in FIG. 13 was produced as follows.
15 On a transparent substrate la, a black matrix 5
was formed by using the same black matrix-forming
resist 1 as that used in Example 1. On this
transparent substrate 1a having a black matrix 5 formed
thereon, a transparent conductive film 3 formed from
20 ITO was formed by using a sputtering apparatus, and
then a slit was formed in the ITO film by the same
process as that used in Example 3. This served as a
third electrode.
Subsequently, a red pixel 15, a green pixel 14, a
25 blue pixel 16, and a first transparent resin layer 7
were formed in the same manner as in Example 3, and
thus a color filter substrate 10 was obtained.
98
Meanwhile, for the green composition and the blue
composition, the same color resists as those used in
Example 3 were used, but for the formation of the red
pixel 15, a red composition 3 such as described below
5 was used. The film thickness of each of the color
layers was set to 2.5 pm.
[Preparation of red pigment 3]
A mixture of the composition described below was
uniformly stirred and mixed, and then the mixture was
10 dispersed with a sand mill for 5 hours by using glass
beads having a diameter of 1 mm. Subsequently, the
dispersion was filtered through a filter having a pore
size of 5 pm, and thus a dispersion of a red pigment 3
was produced.
15 Red pigment: C.I. Pigment Red 254 8 parts
("IRGA FOR RED B-CF" manufactured by Ciba
Specialty Chemicals Corp.)
Red pigment: C.I. Pigment Red 177 12 parts
("CHROMOPHTAL RED A2B" manufactured by Ciba
20 Specialty Chemicals Corp.)
Dispersant ("AJISPER-PB821" manufactured by
Ajinomoto Fine-Techno Co., Inc.) 2 parts
Acrylic varnish (solids content: 20% by mass)
108 parts
25 [Preparation of red composition 3]
Thereafter, a mixture of the composition described
below was stirred and mixed so as to be uniform, and
99
then the mixture was filtered through a filter having a
pore size of 5 pm. Thus, a red composition was
obtained.
5
Red pigment 3
Acrylic resin solution
45 parts
18 parts
Dipentaerythritol penta- and hexa-acrylate ("M402"
manufactured by Toagosei Co., Ltd.) 4.5 parts
Photopolymerization initiator 1.2 parts
("IRGACURE 907" manufactured by Ciba Specialty
10 Chemicals Corp.)
Sensitizer ("EAB-F" manufactured by Hodogaya
Chemical Co., Ltd.)
Cyclohexanone
2.0 parts
32.3 parts
As shown in the following Table 3, the magnitudes
15 of relative permittivity of the respective color layers
were in a relation of red pixel > green pixel > blue
pixel.
Table 3
Example 9
Red Green Blue
Measurement
frequency
layer layer layer
(R) (G) (B)
120 Hz 3.7 3.5 3.1
Relative
240 Hz 3.6 3.4 3.0
permittivity
480 Hz 3.6 3.4 3.0
20
The color filter substrate 10 and the array
substrate 20 having the same configuration as that of
Example 8 were sealed in the form of a liquid crystal
having negative dielectric constant anisotropy being
100
interposed therebetween, and a polarizing plate and a
retardation plate were attached thereto. Thus, a
liquid crystal display device was obtained. On the
surfaces of the color filter substrate and the array
5 substrate, a vertically aligned film had been applied
in advance.
This liquid crystal display device was driven, and
the pixels of the various colors exhibited almost the
same rise at the same driving voltage. Thus, a
10 satisfactory display that was homogeneous could be
obtained.
[Example 10]
In the present Example, a liquid crystal display
device illustrated in FIG. 18 was produced.
15 As illustrated in FIG. 18 or FIG. 19, a color
filter substrate 60 and an array substrate 50 having an
active element such as a TFT formed thereon were sealed
together, and a liquid crystal 17 having negative
dielectric constant anisotropy was encapsulated between
20 the two substrates. A polarizing plate was further
attached on each of the two faces, and thus a liquid
crystal display device was obtained. On the surfaces
of the color filter substrate and the array substrate,
a vertically aligned film had been applied and formed
25 in advance. The array substrate 60 was arranged such
that an array substrate with the same openings and
comb-shaped electrodes as those used in Example 6 was
101
used.
Regarding the color filter substrate 60, a product
obtained by further forming a linear conductor 4 as a
transparent conductive film on the color filter
5 substrate of Example 4 was used. The linear conductor
4 had an image line width of 6 pm, and a spacing width
of 8 pm. The third electrode 3, linear conductor 4 and
second electrode 2 were all used as cornmon electrodes.
Meanwhile, since the linear conductor 4 was
10 formed, from the viewpoint of liquid crystal driving,
the slit 18 shown in FIG. 18 or FIG. 19 may not be
formed.
[Example 11J
In the present Example, a liquid crystal display
15 device illustrated in FIG. 11 was produced as follows.
Regarding the color filter substrate 10, the same
color filter substrate as that used in Example 5 was
used.
The array substrate 30 includes a light reflective
20 film 21 formed from an aluminum alloy thin film at the
same position in a planar view as that of the second
transparent resin layer 8. The reflective film 21 is
electrically independent, and no voltage is applied
thereto.
25 The color layer on the second transparent resin
layer 8 is formed thinly, and the light transmittance
at the reflection region illustrated in FIG. 11 is
102
higher than the transmittance at the transmission
region. That is, regions having two different
transmittances, which are partitioned into a reflection
region and a transmittance region, are included on the
5 color filter substrate.
As illustrated in FIG. 11, at the time of applying
a driving voltage to the liquid crystals, the liquid
crystals 28 in the reflection region have an angle of
inclination different from that of the liquid crystals
10 in the transmission region. A reflective display can
be achieved by adjusting the retardation of the liquid
crystals 28 in the reflection region to approximately a
half of the retardation of the transmission region.
Furthermore, there is no height difference in a section
15 view between the reflection region and the transmission
region in the present Example, and a decrease in the
display characteristics caused by a height difference
(for example, light leakage) does not occur. The
liquid crystal display device illustrated in FIG. 11
20 can be used as a transflective liquid crystal display
device.
When it is said that there is no height difference
between the reflection region and the transmission
region in a section view, it implies that the
25 reflection region and the transmission region are
flattened with a film thickness difference of ±0.3 pm
or less. Furthermore, for example, it is desirable
103
that the surface within one pixel opening be flattened
with a film thickness difference of ±0.135 pm or less,
which corresponds to A/4 of the wavelength of green,
535 nm.
5 [Example 12]
In the present Example, a liquid crystal display
device illustrated in FIG. 24 was produced as follows.
The liquid crystal display device according to the
present Example is a transflective liquid crystal
10 display device using a reflective polarizing plate.
Regarding the reflective polarizing plate, for example,
a reflective polarizing plate described in Japanese
Patent No. 4177398 can be used.
The color filter substrate 10 used in the present
15 Example is, for example, the color filter substrate of
Example 4 illustrated in FIG. 4. The array substrate
20 having an active element (TFT) formed thereon was
prepared as, for example, an array substrate having
comb-shaped electrodes as illustrated in FIG. 22.
20 A color filter substrate 10 and an array substrate
20 were disposed to face each other, and the two
substrates were sealed together, with a liquid crystal
17 having negative dielectric constant anisotropy being
interposed therebetween. On the side of the color
25 filter substrate 10 opposite to the liquid crystal 17,
an optical compensation layer 31a and a polarizing
plate 32a are disposed. Furthermore, on the side of
• 104
the array substrate 20 opposite to the liquid crystal
17, a polarizing plate 32b, a light diffusion layer
33a, a reflective polarizing plate 34, an optical
compensation layer 31b, a prism sheet 35, a light
5 diffusion layer 33b, a light guide plate 36, and a
light reflective plate 37 are provided in sequence.
The light guide plate 36 is provided with a light
source, for example, an LED light source 38.
The LED light source 38 is preferably an RGB
10 individual light emitting element, but a pseudo-white
LED may also be used. Also, instead of an LED< a cold
cathode ray tube or a fluorescent lamp that are
conventionally used for general purposes may also be
used. When an RGB individual light emitting element is
15 employed as the LED light source 38, since the
respective luminescence intensities can be adjusted
individually for the various colors, an optical color
display can be achieved. Furthermore, the liquid
crystal display device can also be applied to a
20 stereoscopic image display or to the control of the
viewing angle. The technique of local dimming, which
is a technology of adjusting the brightness of the
backlight by controlling the area of the display screen
and enhancing the contrast, can be easily applied to
25 LED light sources, and as an normal display region and
a dynamic display region according to the present
invention are used in combination, an enhancement of
105
image quality that has never been observed can be
obtained. In the technique of local dimming, not the
edge light system as shown in FIG. 24, but a nearsource
type backlight system in which the LED light
5 source for RGB individual light emission is disposed on
the back surface of the liquid crystal display device,
can achieve a high image quality display with a finer
area control.
According to the embodiments of the present
10 invention described above, a color filter substrate for
a liquid crystal display device in which a balance is
achieved between a gradation display and an improvement
in responsiveness, and a liquid crystal display device
equipped with this color filter substrate are provided.
15 Particularly, a liquid crystal display device having a
high transmittance which has solved the problem of
disclination can be provided. According to an
embodiment of the present invention, a color filter
substrate for a liquid crystal display device which
20 does not destroy the color balance and enables a
display with a dynamic feeling by particularly
emphasizing brightness, without increasing the number
of TFT elements, and a liquid crystal display device
equipped with this color filter substrate can be
25 provided.
Furthermore, according to an embodiment of the
present invention, there is provided a liquid crystal
• 106
display device which enables a reflective display with
a satisfactory color balance, without exhibiting a
yellow tinge, even when applied to a transflective or
reflective type liquid crystal display.
5 Also, according to an embodiment of the present
embodiment, since a dynamic bright display can be
obtained without increasing the number of pixels such
as white pixels or yellow pixels, there is provided a
liquid crystal display device in which there are no
10 dead pixels as in the case of white pixels occurring at
the time of conventional gradation display, the problem
of disclination that decreases the transmittance of the
liquid crystals is solved, and a brighter display than
conventional displays is enabled.
15 Furthermore, since a configuration can be adopted
in which a transparent conductive film is laminated so
as to cover the effective display pixels of the color
filter, a liquid crystal display device which, as a
side effect, is not easily affected by an external
20 electric field, unlike an IPS (liquid crystals are
driven in a lateral electric field) system or an FFS
(liquid crystals are driven in an electric field that
is generated in the fringe of a comb-shaped electrode),
can be provided.
25 In addition, the rectangular pixel of the liquid
crystal display device according to an embodiment can
be partitioned into 1/2 pixels or 1/4 pixels by axial
107
symmetry or point symmetric with respect to the pixel
center at the first transparent resin layer. However,
when a driving system is adopted in which two or four
TFT elements are formed in one pixel and different
5 voltages are applied to different TFT elements,
adjustment of the viewing angle or a stereoscopic image
display can be achieved.

5
108
We Claim:
1. A color filter substrate for an oblique
electric field liquid crystal display device, the color
filter substrate characterized by comprising:
a transparent substrate;
a black matrix that is formed above the
transparent substrate and comprises openings having a
polygonal shape in which opposite sides are parallel to
each other;
10 a transparent conducive film that is provided
above the black matrix and the transparent substrate
within the openings;
color pixels of plural colors each having a
polygonal shape in which opposite sides are parallel to
15 each other, each of the color pixels being provided
above the transparent conductive film and comprising,
within each of the openings, a region that is
partitioned into two regions respectively having
different transmittances; and
20
25
a first transparent resin layer that is provided
so as to cover the color pixels.
2. A color filter substrate for an oblique
electric field liquid crystal display device, the color
filter substrate characterized by comprising:
a transparent substrate;
a transparent conductive film that is formed above
the transparent substrate;
109
a black matrix that is provided above the
transparent conductive film and comprises openings
having a polygonal shape in which opposite sides are
parallel to each other;
5 color pixels of plural colors each having a
polygonal shape in which opposite sides are parallel to
each other, each of the color pixels being provided
above the black matrix and above the transparent
conductive film within the openings and comprising,
10 within each of the openings, a region that is
partitioned into two regions respectively having
different transmittances; and
a first transparent resin layer that is provided
so as to cover the color pixels,
15 wherein the black matrix is formed of a material
having a higher relative permittivity than relative
permittivities of the color pixels.
3. The color filter substrate for the oblique
electric field liquid crystal display device according
20 to claim 1, characterized in that the two regions
respectively having different transmittances are
partitioned into a region of a thin color layer which
covers a stripe-shaped second transparent resin layer
that passes through a central area of the opening; and
25 a region of the color layer other than that, above the
transparent conductive film within the opening.
4. The color filter substrate for the oblique
110
electric field liquid crystal display device according
to claim 3, characterized in that the second
transparent resin layer passes through a center of the
opening having the polygonal shape and is disposed in
5 parallel to one side of the polygonal shape.
5. The color filter substrate for the oblique
electric field liquid crystal display device according
to claim 4, characterized in that a relative
permittivity of the second transparent resin layer is
10 lower than relative permittivities of the color layers.
6. The color filter substrate for the oblique
electric field liquid crystal display device according
to claim 1, characterized in that the transparent
conductive film passes through a center of the opening
15 having the polygonal shape and has a linear slit that
is parallel to one side of the polygonal shape.
7. A color filter substrate for an oblique
electric field liquid crystal display device, the color
filter substrate characterized by comprising:
20 a transparent substrate;
a transparent conductive film that is formed above
the transparent substrate;
a black matrix that is provided above the
transparent conductive film and comprises openings
25 having a polygonal shape in which opposite sides are
parallel to each other; and
color pixels of plural colors each having a
111
polygonal shape in which opposite sides are parallel to
each other, each of the color pixels being provided
above the black matrix and above the transparent
conductive film within each of the openings,
5 wherein the transparent conductive film has, at a
central area of each of the openings, a linear slit
that is parallel to a side in a longitudinal direction
of the opening.
8. A color filter substrate for an electric field
10 liquid crystal display device, the color filter
substrate characterized by comprising:
a transparent substrate;
a black matrix that is formed above the
transparent substrate and comprises openings having a
15 polygonal shape in which opposite sides are parallel to
each other;
a transparent conductive film that is provided
above the black matrix and above the transparent
substrate within the openings; and
20 color pixels of plural colors each having a
polygonal shape in which opposite sides are parallel to
each other, the color pixels being provided above the
transparent conductive film,
wherein the transparent conductive film has, at a
25 central area of each of the openings, a linear slit
that is parallel to a side in a longitudinal direction
of the opening.
112
9. The color filter substrate for the oblique
electric field liquid crystal display device according
to claim 1, characterized in that the opening having
the polygonal shape has a rectangular shape in a planar
5 view.
10. The color filter substrate for the oblique
electric field liquid crystal display device according
to claim 1, characterized in that the opening having
the polygonal shape has a quadrilateral shape having
10 long sides and short sides, and is folded in a form of
the "symbol <" in a planar view near a center in a
direction of the long side.
11. The color filter substrate for the oblique
electric field liquid crystal display device according
15 to claim 1, characterized in that the opening having
the polygonal shape has a parallelogram shape in a
planar view, and respective one-halves of the number of
color pixels of same color have parallelogram shapes
with two kinds of different angles of inclination.
20 12. The color filter substrate for the oblique
electric field liquid crystal display device according
to claim 1, characterized in that the color pixels of
plural colors comprise color pixels of three colors of
red pixels, green pixels and blue pixels, and
25 respective relative permittivities of the color pixels
measured at a frequency for driving liquid crystals are
in a range of from 2.9 to 4.4, while the relative
113
permittivity of each of the color pixels is in a range
of ±0.3 with respect to an average relative
permittivity of the red pixels, green pixels and blue
pixels.
5 13. The color filter substrate for the oblique
electric field liquid crystal display device according
to claim 1, characterized in that the color pixels of
plural colors comprise color pixels of three colors of
red pixels, green pixels and blue pixels, and
10 magnitudes of respective relative permittivities of the
color pixels measured at a frequency for driving liquid
crystals are in a relation of red pixel > green pixel >
blue pixel.
14. The color filter substrate for the oblique
15 electric field liquid crystal display device according
to claim 13, characterized in that a primary coloring
agent for the green pixels is a halogenated zinc
phthalocyanine pigment.
15. An oblique electric field liquid crystal
20 display device, characterized by comprising:
the color filter substrate according to claim 1;
an array substrate disposed to face the color
filter substrate, the array substrate having elements
for driving liquid crystals arranged in a matrix form;
25 and
a liquid crystal layer interposed between the
color filter substrate and the array substrate,
114
wherein the array substrate comprises a first
electrode and a second electrode, to which different
potentials are applied in order to drive liquid
crystals, correspondingly in each of the color pixels
5 of the color filter substrate in a planar view.
16. The oblique electric field liquid crystal
display device according to claim 15, characterized in
that when a driving voltage is applied between the
first electrode, and the second electrode and a third
10 electrode which is the transparent conductive film,
liquid crystal molecules in a region of liquid crystals
corresponding to the opening move so as to tilt in
opposite directions that are axially symmetric with
respect to a straight line which passes through a
15 center of the opening and bisects the opening in a
planar view.
17. The oblique electric field liquid crystal
display device according to claim 15, characterized in
that in a region of liquid crystals corresponding to
20 the opening, directions in which liquid crystal
molecules would tilt when a voltage for driving the
liquid crystals is applied, are partitioned into four
different regions with respect to a center of the
opening in a planar view.
25 18. The oblique electric field liquid crystal
display device according to claim 15, characterized in
that the first electrode has a comb-shaped pattern that
115
is connected to an active element for driving the
liquid crystals, the second electrode has a comb-shaped
pattern provided below the first electrode across an
insulating layer, and the second electrode protrudes
5 from an end of the first electrode in a direction that
becomes distant from a center that bisects the opening
in a planar view.
19. The oblique electric field liquid crystal
display device according to claim 15, characterized in
10 that the first electrode is not provided above the
array substrate at a position in a planar view where
the second transparent resin layer is provided.
20. The oblique electric field liquid crystal
display device according to claim 15, characterized in
15 that a light reflective film is provided above the
array substrate at a position in a planar view where
the second transparent resin layer is provided.
21. An oblique electric field liquid crystal
display device, characterized by comprising:
20 a color filter substrate comprising a transparent
substrate, a black matrix that is formed above the
transparent substrate and comprises openings having a
polygonal shape in which opposite sides are parallel to
each other, a transparent conductive film that is
25 provided above the black matrix and above the
transparent substrate within the openings, and color
pixels of plural colors that are formed above the
116
transparent conductive film and each have a polygonal
shape in which opposite sides are parallel to each
other, with the transparent conductive film having, at
a center of each of the openings, a linear slit that is
5 parallel to a side in a longitudinal direction of the
opening;
an array substrate that is disposed to face the
color filter substrate and comprises a first electrode
having a comb-shaped pattern that is connected to an
10 active element for driving liquid crystals, and a
second electrode having a comb-shaped pattern that is
provided with an insulating layer interposed between
the first electrode and the second electrode, and
protrudes from an end of the first electrode in a
15 direction that becomes distant from a center that
bisects the opening in a planar view; and
a liquid crystal layer that is interposed between
the color filter substrate and the array substrate.
22. An oblique electric field liquid crystal
20 display device, characterized by comprising:
a color filter substrate comprising a transparent
substrate, a transparent conductive film formed above
the transparent substrate, a black matrix that is
formed above the transparent conductive film and
25 comprises openings having a polygonal shape in which
opposite sides are parallel to each other, and color
pixels of plural colors that are formed above the black
117
matrix and above the transparent conductive film within
the openings and each have a polygonal shape in which
opposite sides are parallel to each other, with the
transparent conductive film having, at a center of each
5 of the openings, a linear slit that is parallel to a
side in a longitudinal direction of the opening;
an array substrate that is disposed to face the
color filter substrate and comprises a first electrode
having a comb-shaped pattern that is connected to an
10 active element for driving liquid crystals, and a
second electrode having a comb-shaped pattern that is
provided with an insulating layer interposed between
the first electrode and the second electrode, and
protrudes from an end of the first electrode in a
15 direction that becomes distant from a center that
bisects the opening in a planar view; and
a liquid crystal layer that is interposed between
the color filter substrate and the array substrate.
23. An oblique electric field liquid crystal
20 display device, characterized by comprising:
an array substrate comprising a first electrode
having a comb-shaped pattern that is connected to an
active element for driving liquid crystals, and a
second electrode having a comb-shaped pattern that is
25 provided with an insulating layer interposed between
the first electrode and the second electrode, and
protrudes from an end of the first electrode in a
118
direction that becomes distant from a center that
bisects the opening in a planar view;
a color filter substrate that is disposed to face
the array substrate and comprises a transparent
5 substrate, a transparent conductive film formed above
the transparent substrate, a black matrix that is
formed above the transparent conductive film and
comprises openings having a polygonal shape in which
opposite sides are parallel to each other, color pixels
10 of plural colors that are formed above the black matrix
and above the transparent conductive film within the
openings and each have a polygonal shape in which
opposite sides are parallel to each other, a first
transparent resin layer provided so as to cover the
15 color pixels, and a set of linear conductors formed
from a transparent conductive film, the linear
conductors being disposed above the first transparent
resin layer and being disposed symmetrically with
respect to a center of the pixel and in parallel to the
20 comb-shaped pattern of the second electrode on an inner
side of the second electrode that is closest to a pixel
center in a planar view; and
a liquid crystal layer that is interposed between
the array substrate and the color substrate.
25 24. An oblique electric field liquid crystal
display device characterized by comprising a reflection
region and a transmission region,
119
the liquid crystal display device comprising:
an array substrate comprising a first electrode
having a comb-shaped pattern that is connected to an
active element for driving liquid crystals, a second
5 electrode having a comb-shaped pattern that is provided
with an insulating layer interposed between the first
electrode and the second electrode, and protrudes from
an end of the first electrode in a direction that
becomes distant from a center that bisects the opening
10 in a planar view, and a light reflective film in the
reflection region;
a color filter substrate comprising a transparent
substrate, a transparent conductive film formed above
the transparent substrate, a second transparent resin
15 layer that is provided above the transparent conductive
film and provided in the reflection region in a planar
view, color pixels of plural colors that are provided
above the transparent conductive film and each have a
polygonal shape in which opposite sides are parallel to
20 each other, and a first transparent resin layer that is
provided so as to cover the color pixels, wherein there
is no height difference in a section view between the
reflection region and the transmission region within
the opening; and
25 a liquid crystal layer that is interposed between
the array substrate and the color filter substrate.
25. The oblique electric field liquid crystal
5
120
display device according to claim 21, characterized in
that the first electrode and the second electrode are
formed from a conductive metal oxide that is
transparent to a visible light region.
26. The oblique electric field liquid crystal
display device according to claim 21, characterized in
that the liquid crystals have negative dielectric
constant anisotropy.
Dated this \ 4~ day of June 2013
Of Anand and Anand Advocates
Agent for the Applicant