Title: Color filter substrate, electrooptic device and electronic apparatus, and methods for manufacturing color filter substrate and electrooptic device
Abstract: A liquid crystal device 1 has liquid crystal 110 provided between a counter substrate 2a and a color filter substrate 2b. The liquid crystal device 1 has a pixel region 100, a first peripheral region 101 surrounding this pixel region 100, and a second peripheral region 102 surrounding the first peripheral region 101. In the first peripheral region 101, a color layer 120 is disposed which is formed of the same color material as that for a reflective blue color layer 150B disposed in the pixel region 100. In the second peripheral region 102, a laminate film 140 composed of color layers 140B, 140R, and 140B is disposed, these color layers described above being formed of the same color materials as those for a non-reflective blue color layer 160B, a non-reflective red color layer 160R, and a non-reflective green color layer 160G, respectively.
Patent Number: 6,992,737 Issued on 01/31/2006 to Kaneko, et al.
| Inventors:
|
Kaneko; Hideki (Shiojin, JP);
Takizawa; Keiji (Hotaka-machi, JP);
Nakano; Tomoyuki (Toyoshina-machi, JP)
|
| Assignee:
|
Seiko Epson Corporation (JP)
|
| Appl. No.:
|
361033 |
| Filed:
|
February 6, 2003 |
Foreign Application Priority Data
| Mar 08, 2002[JP] | 2002-063852 |
| Current U.S. Class: |
349/106; 349/111; 349/114; 349/64 |
| Current Intern'l Class: |
G02F 1/13.35 (20060101) |
| Field of Search: |
349/106,110,113,64,112,111
|
References Cited [Referenced By]
U.S. Patent Documents
| 5910829 | Jun., 1999 | Shimada et al.
| |
| 6281952 | Aug., 2001 | Okamoto et al.
| |
| 6384882 | May., 2002 | Nagayama et al.
| |
| 6445432 | Sep., 2002 | Yamamoto et al.
| |
| 6608660 | Aug., 2003 | Okamoto et al.
| |
| Foreign Patent Documents |
| 6-33133 | Apr., 1994 | JP.
| |
| 10-062768 | Mar., 1998 | JP.
| |
| 11-242226 | Sep., 1999 | JP.
| |
| 11-305248 | Nov., 1999 | JP.
| |
| 2000/-029014 | Jan., 2000 | JP.
| |
| 2000/-111894 | Apr., 2000 | JP.
| |
| 2000/-267077 | Sep., 2000 | JP.
| |
| 2000/-298271 | Oct., 2000 | JP.
| |
| 2001/-033768 | Feb., 2001 | JP.
| |
Primary Examiner: Chowdhury; Tarifur R.
Assistant Examiner: Duong; Tai
Attorney, Agent or Firm: Harness, Dickey & Pierce, P.L.C.
Claims
What is claimed is:
1. A color filter substrate comprising:
a substrate comprising a pixel region and a first peripheral region surrounding
the pixel region on a first surface of the substrate;
a plurality of pixel region color layers disposed on the first surface of the
substrate in the pixel region; and
a peripheral color layer disposed in the first peripheral region, said peripheral
color layer being composed of the same material as one pixel region color layer,
the peripheral color layer having a single layer structure;
wherein the substrate further comprises a second peripheral region surrounding
the first peripheral region, said second peripheral region including a laminate
film which is formed of the same materials as the materials used for at least two
of the pixel region color layers.
2. A color filter substrate according to claim 1 wherein the height of the laminate
film from the first surface is lower than the height of said plurality of pixel
region color layers.
3. A color filter substrate according to claim 2, further comprising a reflective
film disposed in the pixel region.
4. A color filter substrate according to claim 3, further comprising a light
scattering resin layer disposed in the pixel region, and wherein the reflective
film is provided on the light scattering resin layer.
5. A color filter substrate according to claim 4, further comprising a plurality
of pixels in the pixel region, wherein the pixels each have reflective regions
on which the reflective film is disposed and non-reflective regions on which the
reflective film is not disposed.
6. A color filter substrate according to claim 5, wherein the reflective regions
are each disposed so as to surround the non-reflective regions.
7. A color filter substrate according to claim 6, wherein the thicknesses of
the color layers disposed in the reflective regions are different from those of
the color layers disposed in the non-reflective regions.
8. A color filter substrate according to claim 7, wherein said peripheral region
color layer is composed of the same material as that for one color layer of said
color layers disposed in the reflective regions.
9. A color filter substrate according to claim 7, wherein the laminate film is
composed of the same materials as those materials used for at least two color layers
of said color layers disposed in the non-reflective regions.
10. A color filter substrate according to claim 9, wherein the peripheral region
color layer is blue in color.
11. An electrooptic device comprising:
a color filter substrate including:
a substrate having a pixel region and a first peripheral region surrounding the
pixel region on a first surface of the substrate;
a plurality of pixel region color layers disposed on the first surface of the
substrate in the pixel region;
a peripheral region color layer which is disposed in the first peripheral region
and which is composed of the same material as one pixel region color layer;
a counter substrate disposed to oppose the color filter substrate;
an electrooptic material provided between the color filter substrate and the
counter substrate; and
a metal film on the counter substrate so as to correspond to the first peripheral
region of the color filter substrate.
12. An electrooptic device according to claim 11, wherein the metal film comprises tantalum.
13. An electrooptic device according to claim 12, further comprising a backlight
which emits light to the color filter substrate and the counter substrate with
the electrooptic material provided therebetween.
14. An electrooptic device according to claim 13, wherein the electrooptic material
comprises liquid crystal.
15. An electrooptic device according to claim 14 which is incorporated into electronic apparatus.
Description
TECHNICAL FIELD OF THE INVENTION
The present invention relates to color filter substrates for use in electrooptic
devices performing color display, to electrooptic devices and electronic apparatuses,
both using the color filter substrates, and to methods for manufacturing a color
filter substrate and an electrooptic device.
DESCRIPTION OF THE RELATED ART
An active matrix color liquid crystal device using switching elements, which
is
one example of an electrooptic device, is formed of liquid crystal used as an electrooptic
material provided between a color filter substrate and a counter substrate opposing thereto.
In liquid crystal devices using, for example, TFD (Thin Film Diode) elements
as
a switching element, a plurality of line wires arranged in a stripe pattern are
disposed on the counter substrate, and pixel electrodes are connected to the line
wires via the TFD elements. In addition, on the color filter substrate, a plurality
of electrodes arranged in a stripe pattern are provided so as to perpendicularly
intersect the line wires on the counter substrate and to oppose the pixel electrodes.
Furthermore, on the color filter substrate, red color layers (R), blue color layers
(B), and green color layers (G) are disposed for performing color display. In this
type of liquid crystal device, each point at which the pixel electrode and the
electrode on the color filter substrate intersects each other forms one dot, and
one of picture elements R, G, and B is disposed for each dot thus formed. Three
color dots R, G and B form one unit functioning as one pixel.
Heretofore, a shading region made of a metal film is provided to surround
a pixel region in which the pixels are formed, so that the periphery of the pixel
region is darkened, that is, the light transmittance is decreased. Accordingly,
the contrast of the pixel region is enhanced, and the display quality is improved thereby.
However, in the liquid crystal devices having the structure described above,
since it is not necessary to dispose the color layers R, G, and B in the shading
region which has no contribution to display performance, the change in thickness
becomes large in the vicinity of the boundary between the pixel region and the
shading region. Accordingly, the change in cell gap becomes large in the vicinity
of the boundary between the pixel region and the shading region, resulting in orientation
defect of the liquid crystal in the peripheral region of the display screen. As
a result, shading cannot be sufficiently performed only by the metal film, and
a problem occurs in that the display quality is degraded.
The present invention was made to solve the problem described above, and an object
of the present invention is to provide a color filter substrate which has high
display quality obtained by superior shading properties at the periphery of a display
screen; an electrooptic device and an electronic apparatus; and methods for manufacturing
a color filter substrate and an electrooptic device.
SUMMARY OF THE INVENTION
To these ends, a color filter substrate of the present invention comprises: a
substrate comprising a pixel region and a first region surrounding the pixel region
on a first surface of the substrate; a plurality of color layers disposed on the
first surface of the substrate in the pixel region; and a color layer which is
disposed in the first region and which is composed of the same material as that
for one color layer of said plurality of color layers disposed on the first surface
of the substrate.
According to this structure, since the color layer disposed in the first
region is composed of the same layer as that for one of the color layers disposed
in the pixel region, a step is not formed by the difference in thickness of the
film in the vicinity of the boundary between the pixel region and the first region.
Accordingly, in the vicinity of the boundary between the pixel region and the first
region, the film formed on the color filter substrate is continuous, and the change
in thickness thereof is decreased. Hence, when the color filter substrate formed
as described above is incorporated in an electrooptic device, the change in cell
gap in the vicinity of the boundary between the pixel region and the first region
can be reduced, and as a result, degradation of display quality, which is caused
by orientation defect of liquid crystal used as an electrooptic material, can be prevented.
In addition, the substrate may further comprise a second region surrounding the
first region, and the color filter substrate may further comprise a laminate film
which is disposed in the second region and which is formed of the same materials
as those for at least two color layers of said plurality of color layers disposed
on the first surface of the substrate.
According to this structure, since the laminate film composed of the color
layers is formed in the second region surrounding the first region, this portion
serves as a shading region. Accordingly, when the color filter substrate as described
above is incorporated in an electrooptic device, the contrast of the pixel region
can be enhanced, and as a result, a liquid crystal device having high display quality
can be obtained.
The height of the laminate film disposed in the second region from the first
surface may be lower than that of said plurality of color layers in the pixel region
from the first substrate.
According to this structure, when the color filter substrate formed as
described above is bonded to a counter substrate to form an electrooptic device,
a holding material such as spacers, which hold the distance between the two substrates,
may not move, and the distance between the substrates can be held constant, so
that the display quality of the electrooptic device may not be degraded.
In addition, the color filter substrate may further comprise a reflective film
disposed in the pixel region.
According to this structure, this color filter substrate may be used as
a color filter substrate for an electrooptic device, such as a reflective liquid
crystal device or a transflective liquid crystal device, which performs display
using outside light.
In addition, the color filter substrate may further comprise a light scattering
resin layer disposed in the pixel region, wherein the reflective film is provided
on the light scattering resin layer.
As described above, the structure in which the reflective film is formed on the
light scattering resin layer may be used. In this case, for example, irregularities
are provided on the surface of the light scattering resin layer, and the reflective
film is formed in conformity with the irregularities mentioned above, thereby forming
irregularities on the surface of the reflective film. As a result, outside light
is reflected from this reflective film and is then scattered, thereby increasing
the brightness of the reflected light.
The color filter substrate described above may further comprise a plurality of
pixels in the pixel region, and the pixels each have reflective regions in which
the reflective film is disposed and non-reflective regions in which the reflective
film is not disposed.
According to the structure described above, when the non-reflective regions,
in other words, transmissive regions, are formed in the reflective film, the color
filter substrate described above may be used as a color filter substrate for a
transflective liquid crystal device that is an electrooptic device capable of performing
transmissive and reflective displays. In the present invention, the pixel means
a unit forming a display screen of an electrooptic device and corresponds to one
unit composed of three dots in embodiments described later.
Each of the reflective regions may be disposed so as to surround the corresponding
non-reflective region. As described above, both the reflective regions and the
non-reflective regions may be likewise disposed.
In addition, the thicknesses of the color layers disposed in the reflective regions
are different from those of the color layers disposed in the non-reflective regions.
As described above, when the color filter substrate in which the thicknesses
of
the color layers disposed in the reflective regions are different from those of
the color layers disposed in the transmissive regions is incorporated in an electrooptic
device, the same color display quality can be obtained in both transmissive and
reflective display.
In addition, the color layer disposed in the first region is preferably composed
of the same material as one color layer of the color layers disposed in the reflective region.
According to the structure described above, a step formed by the difference
in thickness of the color layer may not be generated in the vicinity of the boundary
between the pixel region and the first peripheral region. That is, since the structure
is formed so that color layers disposed in the reflective regions are each formed
so as to surround a corresponding color layer disposed in the non-reflective region,
when the entire pixel region is observed, the color layers disposed in the reflective
regions are disposed at the periphery of the pixel region. Accordingly, when the
color layer in the first region is formed of the same material and by the same
step as those for the color layers disposed in the reflective regions, the step
formed by the difference in thickness of the color layer may not be generated in
the vicinity of the boundary between the pixel region and the first region. Hence,
when the color filter substrate as described above is incorporated in an electrooptic
device, the change in cell gap in the vicinity of the boundary between the pixel
region and the first peripheral region can be reduced, and hence degradation of
display quality caused by orientation defect of liquid crystal can be prevented.
In addition, the laminate film disposed in the second region may be composed
of
the same materials as those for at least two color layers of said color layers
disposed in the non-reflective regions.
According to this structure, since the color layers disposed in the non-reflective
regions have high shading properties compared to those disposed in the reflective
regions, a laminate film having higher shading properties can be obtained.
In addition, the color layer disposed in the first region is preferably blue
in color.
As described above, blue may be used for the color layer. In general, as the
color
layers, three primary colors, that is, blue, green, and red, are used, and among
those colors, blue has the highest shading properties. Accordingly, by using blue
for the color layer disposed in the first region, a shading function can be obtained.
An electrooptic device of the present invention comprises the color filter substrate
described above, a counter substrate disposed to oppose the color filter substrate,
and an electrooptic material provided between the color filter substrate and the
counter substrate.
According to the structure of the present invention, the change in cell
gap in the vicinity of the boundary between the pixel region and the first region
can be reduced, and degradation of display quality caused by orientation defect
of liquid crystal used as an electrooptic material can be prevented, thereby forming
an electrooptic device having high display quality.
In addition, the electrooptic device described above may further comprise a metal
film on the counter substrate so as to correspond to the first region of the color
filter substrate. According to this structure, the shading function in the first
region can be further enhanced, and the contrast of the pixel region is also enhanced,
thereby forming an electrooptic device having higher display quality.
In addition, the metal film may comprise tantalum. As described above, as the
metal film, a film containing tantalum, such as a tantalum film, a tantalum alloy
film, or a tantalum oxide film, may be used. In addition, the electrooptic device
described above may further comprise a backlight which emits light to the color
filter substrate and the counter substrate with the electrooptic material provided
therebetween. As described above, transmissive display may be performed by the
backlight thus disposed.
In addition, the electrooptic material may comprise liquid crystal. As described
above, as the electrooptic material, liquid crystal may be used. An electronic
apparatus of the present invention comprises the electrooptic device described
above. Accordingly, the electrooptic devices described above may be applied to
various electronic apparatuses.
A method of the present invention for manufacturing a color filter substrate
is
a method for manufacturing a color filter substrate having a substrate which comprises
a pixel region and a first region surrounding the pixel region on a first surface
of the substrate. The method described above comprises a step of forming first
color layers on the first surface of the substrate in the first region and a part
of the pixel region; and a step of forming second color layer on the first surface
of the substrate in the pixel region except at least said part of the pixel region.
According to the structure of the present invention, since the color layer
in the first region is formed of the same material and by the same step as those
for the color layers disposed in the pixel region, an additional step of forming
the color layer in the first region is not necessary, and in the color filter substrate
manufactured by the method described above, a step is not formed by the difference
in thickness of the film in the vicinity of the boundary between the pixel region
and the first region. Accordingly, in the vicinity of the boundary between the
pixel region and the first region, the film formed on the color filter substrate
is continuous, and the change in thickness is decreased. Hence, when the color
filter substrate as described above is incorporated in an electrooptic device,
the change in cell gap in the vicinity of the boundary between the pixel region
and the first region can be reduced, and as a result, degradation of display quality,
which is caused by orientation defect of liquid crystal used as an electrooptic
material, can be prevented.
In addition, the substrate may further comprise a second region surrounding the
first region, and the steps of forming the first color layer and the second color
layer may form a first color layer and a second color layer, respectively, in the
second region so that a laminate film is formed on the first surface of the substrate.
According to the structure described above, since the color layers in the
second region are each formed of the same material and by the same step as those
for the corresponding color layer disposed in the pixel region, additional steps
of forming the color layers in the second region are not necessary, and in the
color filter substrate manufactured by the method described above, the second region
serves as a shading region. Hence, when the color filter substrate as described
above is incorporated in an electrooptic device, the contrast in the pixel region
can be enhanced, and a liquid crystal device having high display quality can be obtained.
In addition, the substrate may further comprise a second region surrounding the
first region, and the method described above may further comprise a step of forming
third color layers on the first surface of the substrate in the pixel region at
which the first color layers and the second color layers are not formed, wherein
the steps of forming the first color layers, the second color layers, and the third
color layers form a first color layer, a second color layer, and a third color
layer, respectively, in the second region so that a laminate film is formed on
the first surface of the substrate.
According to the structure described above, the laminate film may be formed
by the same steps as those for the color layers in the pixel region, and hence
a laminate film having a shading function can be formed without increase in the
number of manufacturing steps. In addition, the height of the laminate film in
the second region from the first surface is preferably lower than the color layers
in the pixel region from the first surface.
When the color filter substrate thus formed is bonded to a counter substrate
with a predetermined gap therebetween to form an electrooptic device, a holding
material such as spacers which hold the distance between the two substrates may
not move, and the distance between the substrates can be held constant, so that
the display quality of the electrooptic device is not degraded.
In addition, the method described above may further comprise a step of forming
a reflective film on the first surface of the substrate in the pixel region, wherein
after the step of forming of the reflective film, the color layers are formed.
The color filter substrate thus formed may be used as a color filter substrate
for an electrooptic device performing display using outside light, such as a reflective
liquid crystal device or a transflective liquid crystal device. In addition, the
method described above may further comprise a step of forming a light scattering
resin layer on the first surface of the substrate in the pixel region, wherein
after the step of forming the light scattering resin layer, the reflective film
is formed.
As described above, a color filter substrate may also be used having the reflective
film formed on the light scattering resin layer. In this case, for example, irregularities
are formed on the surface of the light scattering resin layer, and the reflective
film is formed in conformity with the irregularities mentioned above, thereby forming
irregularities on the surface of the reflective film. As a result, outside light
is reflected from the reflective film and is then scattered, thereby increasing
the brightness of the reflected light.
In addition, the first color layers are preferably blue in color. As described
above, blue may be used for the first color layers. In general, as the color layers,
three primary colors, blue, green, and red, are used, and among those colors, blue
has the highest shading properties. Accordingly, by using blue for the color layer
disposed in the first region, a shading function can be obtained.
In addition, the second color layers are preferably red in color. As described
above, red may be used for the second color layer. In general, as the color layers,
three primary colors, blue, green, and red, are used, and in terms of the shading
properties, red is second best to blue. Accordingly, when a two-layered laminate
film is formed in the second region, blue and red, having higher shading properties
among the three color layers, are preferably used for the color layers, and hence
a more effective shading function can be obtained thereby.
Another method for manufacturing a color filter substrate is a method for
manufacturing a color filter substrate having a substrate which comprises a pixel
region, in which pixels each having reflective regions and non-reflective regions
are disposed, and a first region surrounding the pixel region on a first surface
of the substrate. The method described above comprises a step of forming first
reflective color layers on the first surface of the substrate in the first region
and some of the reflective regions; a step of forming second reflective color layers
on the first surface of the substrate in the reflective regions except at least
said some of the reflective regions; a step of forming first non-reflective color
layers on the first surface of the substrate in said some of the non-reflective
regions; and a step of forming second non-reflective color layers on the first
surface of the substrate in the non-reflective regions except at least said some
of the non-reflective regions.
According to the structure of the present invention, since the color layer
in the first region is formed of the same material and by the same step as those
for the color layers disposed in the pixel region, an additional step of forming
the color layer in the first region is not necessary. In addition, the color filter
substrate manufactured by the method as described above may be used for a transflective
liquid crystal device. In the case described above, when the thickness of the non-reflective
color layer used for transmissive display and the thickness of the reflective color
layer used for reflective display are different from each other, and in addition,
when the reflective color layer is disposed so as to surround the non-reflective
color layer, a step is not formed by the difference in thickness of color layer
in the vicinity of the boundary between the pixel region and the first peripheral
region. That is, when the overall pixel region is observed, since the reflective
color layer is disposed at the periphery of the pixel region, by providing the
color layer in the first region which is formed of the same material and by the
same step as those of the reflective color layers described above, a step is not
formed by the difference in thickness of the color layer in the vicinity of the
boundary between the pixel region and the first peripheral region. Hence, when
the color filter substrate as described above is incorporated in an electrooptic
device, the change in cell gap in the vicinity of the boundary between the pixel
region and the first region can be reduced, and as a result, degradation of display
quality, which is caused by orientation defect of liquid crystal, can be prevented.
In addition, the substrate may further comprise a second region surrounding the
first region, and the steps of forming the first non-reflective color layers and
the second non-reflective color layers may form a first non-reflective color layer
and a second non-reflective color layer, respectively, in the second region so
that a laminate film is formed on the first surface of the substrate.
According to the structure described above, the laminate film can be formed
by the same steps as those for the color layers in the pixel region, and hence
a laminate having a shading function can be formed without increase in the number
of manufacturing steps.
In addition, the substrate may further comprise a second region surrounding the
first region, and the method described above may further comprise a step of forming
third reflective color layers on the first surface of the substrate in the reflective
regions at which the first reflective color layers and the second reflective color
layers are not formed, and a step of forming third non-reflective color layers
on the first surface of the substrate in the non-reflective regions at which the
first non-reflective color layers and the second non-reflective color layers are
not formed, wherein the steps of forming the first non-reflective color layers,
the second non-reflective color layers, and the third non-reflective color layers
form a first non-reflective color layer, a second non-reflective color layer, and
a third non-reflective color layer in the second region so that a laminate is formed
on the first surface of the substrate film.
According to the structure described above, a three-layered laminate film
can be formed by the same steps of forming the color layers in the pixel region,
and without increase in the number of manufacturing steps, a laminate film having
a shading function can be formed.
In addition, the reflective regions are each formed so as to surround the corresponding
non-reflective region, and the method described above may further comprise a step
of forming a reflective film on the first surface of the substrate in the reflective
regions, wherein after the step of forming the reflective film, the color layers
are formed.
As described above, as a reflection mechanism, the reflective film may be formed.
The method described above may further comprise a step of forming a light scattering
resin layer on the first surface of the substrate in the pixel region, wherein
after the step of forming the light scattering resin layer, the reflective film
is formed.
As described above, the light scattering resin layer may be formed. The thicknesses
of the reflective color layers disposed in the reflective regions are preferably
different from those of the non-reflective color layers disposed in the non-reflective regions.
As described above, when the color filter substrate in which the thicknesses
of
the color layers disposed in the reflective regions are different from those of
the color layers disposed in the non-reflective regions, that is, the transmissive
regions, is incorporated in an electrooptic device, the same color display quality
can be obtained in both transmissive and reflective displays.
In addition, the first reflective color layers are preferably blue in color.
Blue
may be used for the first color layer, and hence the color layer formed in the
first region is blue. In general, as the color layers, three primary colors, blue,
green, and red, are used, and among those colors, blue has the highest shading
properties. Accordingly, by using blue for the color layer disposed in the first
region, a shading function can be obtained.
A method of the present invention for manufacturing an electrooptic device is
a
method for manufacturing an electrooptic device comprising an electrooptic material
provided between a color filter substrate and a counter substrate, and in the method
described above, the color filter substrate is manufactured in accordance with
the methods for manufacturing the color filter substrates described above.
According to the structure of the present invention described above, an
electrooptic device having high display quality can be obtained.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a partly exploded plan view of a liquid crystal device of a first
embodiment according to the present invention.
FIG. 2 is a plan view for illustrating the positional relationship among a pixel
region, a first peripheral region, and a second peripheral region of the liquid
crystal device shown in FIG. 1.
FIG. 3 is a partial cross-sectional view showing the structure of the liquid
crystal device taken along the line III—III in FIG. 1.
FIG. 4 is a partial cross-sectional view showing the structure of the liquid
crystal device taken along the line IV—IV in FIG. 1.
FIG. 5 is a partial cross-sectional view showing the structure of the liquid
crystal device taken along the line V—V in FIG. 1.
FIG. 6 is a schematic, perspective view for illustrating the positional relationship
among a reflective film, color layers, and second electrodes of a color filter
substrate of the liquid crystal device shown in FIG. 1.
FIG. 7 is an enlarged perspective view showing a TFD element indicated by the
arrow VII in FIG. 1.
FIG. 8 includes partial cross-sectional views showing a manufacturing process
(part 1) for a color filter substrate of the liquid crystal device shown in FIG. 1.
FIG. 9 includes partial cross-sectional views showing a manufacturing process
(part 2) for the color filter substrate of the liquid crystal device shown in FIG. 1.
FIG. 10 is a partial, cross-sectional view of a liquid crystal device according
to another embodiment of the present invention, and corresponds to the cross-sectional
view taken along the line III—III in FIG. 1.
FIG. 11 is a partial, cross-sectional view of a liquid crystal device according
to another embodiment, and corresponds to the cross-sectional view taken along
the line IV—IV in FIG. 1.
FIG. 12 is a partial, cross-sectional view of a liquid crystal device according
to another embodiment, and corresponds to the cross-sectional view taken along
the line V—V in FIG. 1.
FIG. 13 includes partial, cross-sectional views showing a manufacturing process
for a color filter substrate of a liquid crystal device according to another embodiment.
FIG. 14 is a perspective view showing a mobile computer according to another
embodiment of an electronic apparatus of the present invention.
FIG. 15 is a perspective view showing a mobile phone according to still another
embodiment of an electronic apparatus of the present invention.
FIG. 16 is a perspective view showing a digital still camera according to still
another embodiment of an electronic apparatus of the present invention.
FIG. 17 is a block diagram showing an embodiment of an electronic apparatus
of the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
(First Embodiment)
Hereinafter, the present invention will be described with reference
to drawings about the case in which the present invention is applied to an active
matrix transflective liquid crystal device of the COG-type using TFD elements as
switching elements, which is an example of an electrooptic device. In the drawings,
in order to easily recognize individual constituent elements, the reduction scales,
the number of elements, and the like are differ from those of the actual structure.
FIG. 1 is a plan view showing a liquid crystal device according to an embodiment,
and FIG. 2 is a plan view for illustrating the positional relationship among a
pixel region, a first peripheral region, and a second peripheral region of the
liquid crystal device shown in FIG. 1.
A liquid crystal device
1 shown in FIG. 1 is formed by bonding, that is,
adhering, a counter substrate
2a disposed at the front side of this
figure to a color filter substrate
2b disposed at the rear side of
this figure with a sealing material.
A region surrounded by a sealing material
3, the counter substrate
2a,
and the color filter substrate
2b forms a gap having a predetermined
height, in other words, a so-called cell gap is formed. In addition, a liquid crystal
inlet
3a is formed in a part of the sealing material
3. Into
the cell gap described above, liquid crystal is injected via the liquid crystal
inlet
3a, and after the injection is performed, the liquid crystal
inlet
3a is sealed with a resin or the like.
As shown in FIG. 1, the counter substrate
2a has a substrate protruding
portion
2c which protrudes outside from the color filter substrate
2b, and on this substrate protruding portion
2c, liquid
crystal drive ICs
4a and
4b are mounted with a conductive
adhesive such as an ACF (Anisotropic Conductive Film)
6. The liquid crystal
drive ICs
4a and
4b have different properties from
each other, and the reason the two different types of liquid crystal drive ICs
are used is that one type IC cannot control operation of both the counter substrate
2a and the color filter substrate
2b since voltages
used for scanning lines drive system and signal line drive system are different
from each other.
The structure of each substrate will be described later in detail; however, as
shown in FIGS. 1 and 2, the liquid crystal device
1 has a pixel region
100
having a size approximately equivalent to that of a display screen, a first peripheral
region
101 surrounding this pixel region
100, and a second peripheral
region
102 further surrounding this first peripheral region
101.
Both the first and the second peripheral regions serve as a shading region. The
second peripheral region
102 is disposed so that the outer edge portion
thereof overlaps the inner edge portion of the sealing material
3.
FIG. 3 is a partial cross-sectional view of the liquid crystal device structure
taken along the line III—III in FIG. 1. FIG. 4 is a partial cross-sectional
view of the liquid crystal device structure taken along the line IV—IV in
FIG. 1. The liquid crystal device
1 is formed of liquid crystal
110,
functioning as an electrooptic material, provided between the counter substrate
2a and the color filter substrate
2b. The distance
between the counter substrate
2a and the color filter substrate
2b
is fixed by spacers
111. In addition, at the rear side (lower side of
the structure shown in FIGS. 3 and 4) of the color filter substrate
2b,
a lighting device
10 having a light source
7 and a light guide
8
is provided as a backlight.
As shown in FIGS. 3 and 4, the counter substrate
2a has a substrate
9a, and on the surface of the substrate
9a, that is,
on the surface at the liquid crystal
110 side, a plurality of pixel electrodes
14a are disposed. In addition, as shown in FIG. 1, on the internal
surface of the counter substrate
2a, a plurality of linear line wires
32 are disposed parallel to each other so as to form a stripe pattern, TFD
elements
33 are formed so as to be connected to these line wires
32,
and the plurality of pixel electrodes
14a are disposed in a matrix
via these TFD elements
33. In addition, on the pixel electrodes
14a,
the TFD elements
33, and the line wires
32, as shown in FIGS. 3 and
4, an alignment film
16a is disposed. In addition, a retardation
film
17a is disposed on the external surface of the substrate
9a,
and a polarizer
18a is further disposed on the retardation film
17a.
The structure of one TFD element and the vicinity thereof indicated by the arrow
VII in FIG. 1 is shown in FIG. 7 by way of example. A TFD element shown in FIG.
7 has a so-called back-to-back structure. As shown in FIG. 7, the line wire
32
has a three-layered structure formed of a first layer
32a made of
TaW (tantalum tungsten) or the like, a second layer
32b made of an
anodized Ta
2O
5 (tantalum oxide) film or the like, and a third
layer
32c made of Cr or the like.
In addition, the TFD element
33 is formed by connecting a first TFD portion
33a and a second TFD portion
33b in series. The first
TFD portion
33a and the second TFD portion
33b are
each have a three-layered structure formed of a first metal layer
36 made
of TaW, an insulating layer
37 made of Ta
2O
5 by anodization,
and a second metal layer
38 made of Cr, which is formed of the same layer
as that for the third layer
32c of the line wire
32.
The first TFD portion
33a has a laminate structure in which current
from the line wire
32 side flows through the second metal layer
38,
the insulating layer
37, and the first metal layer
36 in that order.
On the other hand, the second TFD portion
33b has a laminate structure
in which current from the line wire
32 side flows through the first metal
layer
36, the insulating layer
37, and the second metal layer
38
in that order. As described above, by connecting the pair of the TFD portions
33a
and
33b to each other in series so that the electrical directions
thereof are opposite to each other, a TFD element having the back-to-back structure
is formed, and hence stability of switching properties of the TFD element can be
obtained. The pixel electrode
14a is formed, for example, of ITO
so as to be electrically connected to the second metal layer
38 of the second
TFD portion
33b.
In addition, on the counter substrate
2a, a picture-frame shaped
metal film
130 is formed to oppose the first peripheral region
101.
This metal film
130 may have a laminate structure formed, for example, of
the first layer
32a made of TaW (tantalum tungsten) and the second
layer
32b made of an anodized Ta
2O
5 (tantalum
oxide) film of the line wire
32, and the metal film
130 may be formed
in the same steps as those for forming the TFD element. In addition, as the metal
film
130, a single layer may be used which is made of a TaW (tantalum tungsten)
layer formed in the same step as that for the first layer
32a forming
the TFD element.
As shown in FIGS. 3 and 4, the color filter substrate
2b has a
substrate
9b having a first surface
109b. On the first surface
109b of the substrate
9b, that is, on the surface at
the liquid crystal
110 side, a light scattering resin layer
81, having
a thickness of 1.4 to 2.6 μm and being formed, for example, of an acrylic
or epoxy resin, is disposed, and on this light scattering resin layer
81,
a reflective film
11 having a thickness of 160 to 260 nm and being formed
of a material having a light reflective property, such as Al, is further disposed.
Although not shown in the figure, the light scattering resin layer
81 has
an irregular or roughened surface at the side to be brought into contact with the
reflective film
11, and the reflective film
11 is formed in conformity
with this irregularities, thereby forming irregularities on the surface of the
reflective film
11. In addition, the reflective film
11 has an opening
11a in each dot, which allows light to pass therethrough. That is,
when display is performed in accordance with the function of a reflective liquid
crystal device using outside light, outside light incident on the liquid crystal
device
1 is reflected from the reflective film
11, and display is
performed using this reflected light, and when display is performed in accordance
with the function of a transmissive liquid crystal device using a backlight
10,
light emitted from the backlight
10 passes through the openings
11a
formed in the reflective film
11, so that display is performed. In this
embodiment, the transflective function is obtained by forming the openings in parts
of the reflective film
11; however, for example, when the reflective film
is thinned so as to allow light to pass therethrough, the transflective function
can also be obtained. In addition, in this embodiment, in order to efficiently
scatter outside light, the reflective film
11 is formed on the light scattering
resin layer
81 having irregularities on the surface thereof so as to form
irregularities on the surface of the reflective film
11; however, without
the light scattering resin layer
81, after irregularities are formed on
the surface of the substrate
9b by frost treatment or the like, the
reflective film
11 may be formed on the irregular region of the substrate
9b so as to form irregularities on the surface of the reflective
film
11. Alternatively, without the light scattering resin layer
81,
the structure may be formed in which the reflective film
11 is provided
on a flat surface of the substrate
9b to form a flat surface of the
reflective film
11, and a light scattering layer for light scattering is
provided at the external surface side of the substrate
9a.
Furthermore, on the reflective film
11, a color filter film and
an overcoat layer
13 having a thickness of 1.4 to 2.6 μm are disposed,
second electrodes
14b are disposed on the overcoat layer, and an
alignment film
16b is further disposed on those mentioned above.
In addition, on the external surface of the substrate
9b, a retardation
film
17b is formed, and on that film mentioned above, a polarizer
18b is further disposed.
As shown in FIG. 1, the second electrodes
14b are formed of a great
number of linear electrodes disposed in parallel to each other in a stripe pattern
so as to intersect the line wires
32. In FIG. 1, to facilitate understanding
of the electrode pattern, the second electrodes
14b having exaggerated
large spaces therebetween are shown schematically; however, in practice, the spaces
between the second electrodes
14b are formed to be very small in
accordance with dot pitches of the pixel electrodes
14a.
The intersections between the pixel electrodes
14a and the second
electrodes
14b are arranged in a dot matrix, each intersection forms
one dot, and each color layer pattern of the color filter film shown in FIGS. 3
and 4 corresponds to one dot described above.
In the color filter film described above, one unit is composed of three primary
colors R (red), G (green), B (blue), and this unit forms one pixel. That is, three
dots form one unit functioning as one pixel. The color filter film of this embodiment
is formed of reflective blue color layers
150B as a first reflective color
layer, reflective red color layers
150R as a second reflective color layer,
reflective green color layers
150G as a third reflective color layer, non-reflective
blue color layers
160B as a first non-reflective color layer, non-reflective
red color layers
160R as a second non-reflective color layer, and non-reflective
green color layers
160G as a third non-reflective color layer.
Next, referring to FIGS. 3,
4, and
6, the positional relationship
between the color filter film and the reflective film, and the structures thereof
will be described. FIG. 6 is a schematic perspective view for illustrating the
positional relationship among the reflective film
11, the color layers,
and the second electrodes on the color filter substrate
2b of the
liquid crystal device
1 shown in FIG. 1. As shown in the figure, the liquid
crystal device
1 has the structure in which one opening
11a of
the reflective film
11 is provided in each dot. A part of the reflective
film
11, which corresponds to one dot, is formed in the reflection region
171 used for reflection display to surround the opening
11a located
in a non-reflection region
170 used for transmission display. In addition,
the reflective blue color layers
150B, reflective red color layers
150R,
and reflective green color layers
150G are formed approximately along the
second electrodes
14b so as to form a stripe pattern, and at positions
corresponding to the openings
11a of the reflective film
11,
the reflective color layers are not provided. In addition, the non-reflective blue
color layers
160B, non-reflective red color layers
160R, and non-reflective
green color layers
160G are formed at positions corresponding to the openings
11a and approximately along the second electrodes
14b so
that the same color layers are disposed linearly. For the reflective color layers
150 and non-reflective color layers
160, in other words, transmissive
color layers, coloring materials and the thicknesses thereof are different from
each other. In particular, although an organic resin, such as an acrylic, epoxy,
or polyimide resin, is used for both the reflective color layers
150 and
the non-reflective color layers
160, amounts of pigment dispersed therein
or the like are different from each other. In addition, in this embodiment, the
reflective color layer
150 is formed to have a thickness of 1 μm,
and on the other hand, the non-reflective color layer
160 is formed to have
a thickness of 1.5 μm. In addition, among the reflective color layers
150
and the non-reflective color layers
160, each blue color layer has the highest
shading property, and each red color layer is second best to the blue color layer
in shading property. In the figure, the opening
11a formed in the
reflective film
11 is shown as if a space is present therein; however, since
the reflective film
11 has a significantly small thickness compared to that
of the color layers
150 and
160, the openings
11a are
filled with the color layers
160 in practice.
In this embodiment, as shown in FIGS. 3,
4, and
5, FIG. 5 which
is a cross-sectional view taken along the line V—V in FIG. 1, in the first
peripheral region
101 of the color filter substrate
2b, as
a first peripheral color layer, a first peripheral blue color layer
120
in a picture-frame shape is disposed which is formed of the same material and by
the same step as those for the reflective blue color layer
150B disposed
in the pixel region
100. Accordingly, the step of forming the color layer
may be omitted in the vicinity of the boundary between the pixel region
100
and the first peripheral region
101. That is, in this embodiment, since
the color layer in each dot is formed so that the reflective color layer
150
surrounds the non-reflective color layer
160, when the overall pixel region
is observed, the reflective color layer
150 is disposed at the periphery
of the pixel region. Accordingly, when the first peripheral color layer
120,
which is formed of the same material and by the same step as those for this reflective
color layer
150, is provided in the first peripheral region
101,
the step of generating a difference in the thickness of the color layer may not
be omitted in the vicinity of the boundary of the pixel region
100 and the
first peripheral region
101. In addition, in this embodiment, the light
scattering resin layer
81 and the reflective film
11 are formed so
as to overlap at least the inner edge portion of the first peripheral region
101,
and the overcoat layer
13 and the alignment film
16b are also
formed so as to overlap at least the inner edge portion of the first peripheral
region
101. Hence, in the vicinity of the boundary between the pixel region
100 and the first peripheral region
101, the film formed on the color
filter substrate
2b becomes continuous, and hence the change in thickness
is decreased. As a result, compared to traditional structures, the change in cell
gap in the vicinity of the boundary between the pixel region
100 and the
first peripheral region
101 can be reduced, and degradation of display quality
caused by orientation defects of the liquid crystal material can be reduced.
In addition, in this embodiment, since the color layer is disposed in the first
peripheral region
101, light leakage from the backlight can be shaded, and
also in this embodiment, since blue color having high shading property is used
as the first peripheral color layer, light leakage from the backlight can be efficiently
shaded as compared to the case in which another color such as red or green is used.
In this embodiment, blue color is used as the first peripheral color layer; however,
red color or green color may be used, and preferably, blue color or red color having
high shading property is used. Furthermore, as described above, since the metal
film
130 is formed on the counter substrate
2a so as to correspond
to the first peripheral region
101, light leakage from the backlight can
be further shaded, and the contrast of the pixel region can be enhanced, thereby
forming a liquid crystal device having high display quality.
In the second peripheral region
102 of the color filter substrate
2b,
a picture-frame shaped laminate film
140 composed of three color layers
having three different colors from each other, that is, a second peripheral blue
color layer
140B, a second peripheral red color layer
140R, and a
second peripheral green color layer
140G, is disposed, these three color
layers being formed of the same materials and by the same steps as those for the
non-reflective blue color layer
160B, non-reflective red color layer
160R,
and non-reflective green color layer
160G, respectively, which are disposed
in the pixel region
100. As described above, by further forming a shading
film of the laminate film
140 in the second peripheral region
102
surrounding the first peripheral region
101, light leakage from the backlight
can be further shaded, and hence a liquid crystal device having higher display
quality can be obtained. Related to this, in this embodiment, the color layers
having three different colors are used to form the laminate film
140; however,
two color layers having different colors may be used, and in this case, a blue
color layer and a red color layer are preferably formed for forming a laminate
film in order of higher shading ability. In addition, height "a" of the laminate
film
140 from the first surface
109b of the color filter substrate
2b is preferably smaller than height "b" of the color filter film
from the first surface
109b of the color filter substrate
2b.
The reason for this is that when height a is larger than height b, the spacers
111 move when the liquid crystal device
1 is formed, and as a result,
the cell gap in the substrate surface may become nonuniform in some cases.
The substrates
9a and
9b described above are formed,
for example, of glass or plastic. In addition, the electrodes
14a and
14b described above having a desired pattern may be formed by a known
film-forming method, such as sputtering or vacuum deposition, using ITO (Indium
Tin Oxide) or the like and a subsequent photolithographic method.
The alignment films
16a and
16b are formed, for example,
by an offset printing method or a method in which a polyimide solution is applied
and then baked.
As shown in FIG. 1, on the substrate protruding portion
2c of the
counter substrate
2a, wires
19a are formed which are
connected to the third layers
32c of the line wires
32, and
wires
19b are also formed which are connected to the second electrodes
14b on the color filter substrate
2b via a conductive
material
21 (see FIG. 5) dispersed in the sealing material
3. As
the structure of the wire
19a, for example, a laminate structure
may be used which is composed of a Cr (chromium) layer formed by the same step
as that for the third layer
32c and an ITO (Indium Tin Oxide) layer
formed by the same step as that for the second electrodes
14b. In
addition, as the structure of the wire
19a, for example, a laminate
structure may be used which is composed of a Cr (chromium) layer formed by the
same step as that for the third layer
32c and one of a TaW (tantalum
tungsten) layer formed by the same step as that for the first layer
32a
of the TFD element, a Ta
2O
5 (tantalum oxide) layer formed
by the same step as that for the second layer
32b of the TFD element,
and an ITO (Indium Tin Oxide) layer formed by the same step as that for the second
