U.S. patent application number 15/862071 was filed with the patent office on 2018-05-24 for input-capable display device.
The applicant listed for this patent is Japan Display Inc.. Invention is credited to Yoichi FUJIKAWA, Takeshi KOSHIHARA, Takeyoshi USHIKI, Sumio UTSUNOMIYA.
Application Number | 20180143476 15/862071 |
Document ID | / |
Family ID | 39322758 |
Filed Date | 2018-05-24 |
United States Patent
Application |
20180143476 |
Kind Code |
A1 |
UTSUNOMIYA; Sumio ; et
al. |
May 24, 2018 |
INPUT-CAPABLE DISPLAY DEVICE
Abstract
An input-cable display device is provided including a first
substrate on which a pair of electrodes that drive a liquid crystal
layer are provided; a second substrate wherein the liquid crystal
layer is formed within an inner surface of the second substrate
between the first substrate and the second substrate; a detection
electrode and a dielectric film that are laminated on an outer
surface of the second substrate; a detector; a light shielding
film; and a color filter layer, wherein the pair of electrodes
provided on the first substrate comprises a pixel electrode and a
common electrode, and the light shielding film and the color filter
layer are laminated on the inner surface of the second
substrate.
Inventors: |
UTSUNOMIYA; Sumio;
(Matsumoto-shi, JP) ; KOSHIHARA; Takeshi;
(Suwa-shi, JP) ; USHIKI; Takeyoshi; (Shiojiri-shi,
JP) ; FUJIKAWA; Yoichi; (Azumino-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Japan Display Inc. |
Tokyo |
|
JP |
|
|
Family ID: |
39322758 |
Appl. No.: |
15/862071 |
Filed: |
January 4, 2018 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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15177840 |
Jun 9, 2016 |
9891458 |
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15862071 |
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14723073 |
May 27, 2015 |
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15177840 |
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11957047 |
Dec 14, 2007 |
9069401 |
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14723073 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G02F 1/13338 20130101;
G02F 1/13439 20130101; G02F 1/133528 20130101; G02F 1/133784
20130101; G02F 1/134363 20130101; G06F 3/044 20130101; G02F
1/134309 20130101; G02F 1/133514 20130101; G02F 1/136286 20130101;
G02F 2001/136218 20130101; G02F 2201/123 20130101; G02F 1/1368
20130101; G02F 2201/121 20130101; G06F 3/0412 20130101; G06F 3/0443
20190501; G02F 1/133512 20130101; G02F 2001/134345 20130101 |
International
Class: |
G02F 1/1333 20060101
G02F001/1333; G06F 3/044 20060101 G06F003/044; G02F 1/1335 20060101
G02F001/1335; G06F 3/041 20060101 G06F003/041; G02F 1/1337 20060101
G02F001/1337; G02F 1/1368 20060101 G02F001/1368; G02F 1/1362
20060101 G02F001/1362; G02F 1/1343 20060101 G02F001/1343 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 30, 2007 |
JP |
2007-019138 |
Claims
1. A display device comprising: a first substrate including a pair
of electrodes provided thereon, the pair of electrodes comprising a
pixel electrode and a common electrode; a second substrate opposed
to the first substrate; a liquid crystal layer provided between the
first substrate and the second substrate; a polarizer provided on
an outer portion side of second substrate, the outer portion side
being opposite to a liquid crystal layer side of the second
substrate; a light shielding film having conductivity; and a color
filter layer, wherein an electric potential of the light shielding
film is fixed, wherein the light shielding film and the color
filter layer are stacked on the liquid crystal layer side of the
second substrate in order of the light shielding film and the color
filter layer from the side of the second substrate toward the
liquid crystal layer, and wherein the color filter layer covers the
entire light shielding film.
2. The display device according to claim 1, wherein the pair of
electrodes constitute a horizontal electric field mode
structure.
3. The display device according to claim 1, wherein the pair of
electrodes are arranged on different layers.
4. The display device according to claim 1, wherein the light
shielding film has a sheet resistance of 1 k.OMEGA./sq or
below.
5. The display device according to claim 1, wherein the light
shielding film is arranged above a thin film transistor element
that is used for switching the control of the pixel electrode.
6. The display device according to claim 1, further comprising a
detection electrode arranged between the polarizer and the second
substrate.
7. The display device according to claim 1, wherein the pixel
electrode and the common electrode are translucent.
8. The display device according to claim 3, wherein the pixel
electrode is a reflective electrode.
9. A display device comprising: a first substrate including a pair
of electrodes provided thereon, the pair of electrodes comprising a
pixel electrode and a common electrode; a second substrate opposed
to the first substrate; a liquid crystal layer provided between the
first substrate and the second substrate; a dielectric film
provided on an outer portion side of the second substrate, the
outer portion side being opposite to a liquid crystal layer side of
the second substrate; a light shielding film having conductivity;
and a color filter layer, wherein an electric potential of the
light shielding film is fixed, wherein the light shielding film and
the color filter layer are stacked on the liquid crystal layer side
of the second substrate in order of the light shielding film and
the color filter layer from the side of the second substrate toward
the liquid crystal layer, and wherein the color filter layer covers
the entire light shielding film.
10. The display device according to claim 9, wherein the pair of
electrodes constitute a horizontal electric field mode
structure.
11. The display device according to claim 9, wherein the pair of
electrodes are arranged on different layers.
12. The display device according to claim 9, wherein the light
shielding film has a sheet resistance of 1 k.OMEGA./sq or
below.
13. The display device according to claim 9, wherein the light
shielding film is arranged above a thin film transistor element
that is used for switching the control of the pixel electrode.
14. The display device according to claim 9, further comprising a
detection electrode is arranged between the dielectric film and the
second substrate.
15. The display device according to claim 9, wherein the pixel
electrode and the common electrode are translucent.
16. The display device according to claim 11, wherein the pixel
electrode is a reflective electrode.
17. A display device comprising: a base substrate including a pair
of electrodes provided thereon, the pair of electrodes comprising a
pixel electrode and a common electrode; a cover layer above the
first substrate; a polarizer provided on an outer portion side of
the cover layer, the outer portion side being opposite to the base
substrate side of the cover layer; and a light shielding film
having a conductivity arranged above a thin film transistor element
that is used for switching the control of the pixel electrode,
wherein an electric potential of the light shielding film is fixed,
and wherein the pixel electrode is surrounded by the light
shielding film.
18. The display device according to claim 17, further comprising a
detection electrode arranged between the polarizer and the cover
layer.
19. The display device according to claim 17, further comprising a
display function layer provided between the pixel electrode and the
common electrode.
20. The display device according to claim 19, wherein a
predetermined voltage for displaying an image is supplied between
the pixel electrode and the common electrode.
Description
CROSS REFERENCES TO RELATED APPLICATIONS
[0001] The present application is a continuation of U.S. patent
application Ser. No. 15/177,840, filed on Jun. 9, 2016, which
application is a continuation of U.S. patent application Ser. No.
14/723,073, filed on May 27, 2015, which application is a
continuation of U.S. patent application Ser. No. 11/957,047, filed
on Dec. 14, 2007, issued as U.S. Pat. No. 9,069,401 on Jun. 30,
2015, which claims priority to Japanese Priority Patent Application
JP 2007-019138 filed in the Japan Patent Office on Jan. 30, 2007,
the entire content of which is hereby incorporated by
reference.
BACKGROUND
1. Technical Field
[0002] The present invention relates to an input-capable display
device, such as, for example, a touch panel, to which an input
function is added.
2. Related Art
[0003] In recent years, as a compact information electronic
apparatus, such as a personal digital assistants (PDA) or a
personal computer spreads, a display device that has added a
so-called touch panel function, which is used for input operation
by bringing an object, such as a finger or a pen, into contact with
a display screen, has been widely used. In such a touch panel,
there is an electrostatic capacitance method as a method for
detecting a position at which a finger, or the like, contacts,
which is, for example, described in Japanese Unexamined Patent
Application Publication No. 2006-146895 and Japanese Unexamined
Patent Application Publication No. 2003-196023. The electrostatic
capacitance method is a method that flows a weak electric current
through an electrostatic capacitance formed by touching a display
surface with user's finger and thereby detects a position of
contact on the basis of the amount of electric current. Here, in
the electrostatic capacitance method, a detection electrode formed
in a planar manner and a dielectric film laminated on the detection
electrode are used. By touching the dielectric film with the
finger, an electrostatic capacitance is formed.
[0004] In a liquid crystal display device with a touch panel
function that uses the above electrostatic capacitance method,
there is a problem that, when an electric field generated by a
driving signal that is supplied between a pair of electrodes for
driving a liquid crystal layer reaches the detection electrode, the
accuracy of detection of a position of contact is decreased because
this electric field component acts as a noise. Here, in the above
liquid crystal display device with a touch panel function, it is
attempted to remove a noise generated due to a signal that is
generated from a driving signal.
[0005] In the above existing liquid crystal display device with a
touch panel function, however, the following problem still remains.
That is, in the existing liquid crystal display device with a touch
panel function, there is a problem that it. requires a complex
system for generating a signal that removes a noise.
SUMMARY
[0006] An advantage of some aspects of the invention is that it
provides an input-capable display device, which is capable of
suppressing an influence of noise without requiring a complex
system.
[0007] An aspect of the invention employs the following
configuration to solve the problems. That is, an aspect of the
invention provides an input-capable display device. The
input-capable display device includes a first substrate, a second
substrate, a detection electrode, a dielectric film, and a
detector. A pair of electrodes that drive a liquid crystal layer
are provided on the first substrate. The second substrate is
opposed to the first substrate through the liquid crystal layer.
The detection electrode and the dielectric film are laminated on an
outer surface of the second substrate. The detector detects a
position at which an electrostatic capacitance is formed with the
detection electrode through the dielectric film. The second
substrate includes a shield conductor that is formed on a side
adjacent to the liquid crystal layer. An electric potential of the
shield conductor is fixed.
[0008] According to the above aspect of the invention, by providing
the shield conductor in the second substrate on the side adjacent
to the liquid crystal layer, an influence of noise that is
generated due to a driving signal of the liquid crystal layer is
suppressed without excessively thickening the second substrate and
without using a complex system, thus improving the accuracy of
detection of a position of contact on the display surface. That is,
by supplying a driving signal of the liquid crystal layer to the
pair of electrodes, an electric field that is generated to be
directed toward the second substrate is blocked by the shield
conductor. For this reason, it is possible to prevent a coupling
between the pair of electrodes and the detection electrode. Here,
the pair of electrodes that drive the liquid crystal layer are
provided in the first substrate, and a sufficient distance is
ensured between the pair of electrodes and the shield conductor.
Therefore, the strength of electric field that is generated by the
driving signal of the liquid crystal layer and directed toward the
shield conductor is small as compared with the case where a
vertical electric field mode electrode structure is employed. Thus,
the shield conductor effectively blocks the electric field.
Accordingly, without providing an additional complex system and
without excessively thickening the second substrate, a coupling
between the pair of electrodes and the detection electrode is
prevented and thereby an influence of noise due to the driving
signal is suppressed. In addition, by forming the shield conductor
integrally with the second substrate to not excessively thicken the
second substrate, it is possible to ensure a sufficient
transmittance ratio. Furthermore, because the shield conductor and
the detection electrode are sufficiently spaced apart from each
other, it is possible to prevent a capacitance component from being
formed between the shield conductor and the detection
electrode.
[0009] In the input-capable display device according to the aspect
of the invention, the shield conductor may have translucency.
According to the above aspect of the invention, because the shield
conductor is formed of a translucent conductive material, it is
possible to form a shield conductor in a planar shape, and it is
possible to reliably suppress an influence of noise due to a
driving signal of the liquid crystal layer.
[0010] In the input-capable display device according to the aspect
of the invention, the shield conductor may constitute a light
shielding film. According to this aspect of the invention, because
the shield conductor also serves as a light shielding film, the
thickness of the second substrate is reduced.
[0011] In the input-capable display device according to the aspect
of the invention, the dielectric film may constitute a polarizer.
According to this aspect of the invention, because the polarizer is
formed by using a dielectric material, the number of components is
reduced and the thickness of the input-capable display device is
reduced.
[0012] Additional features and advantages are described herein, and
will be apparent from the following Detailed Description and the
figures.
BRIEF DESCRIPTION OF THE FIGURES
[0013] The invention will be described with reference to the
accompanying drawings, wherein like numbers reference like
elements.
[0014] FIG. 1 is a schematic cross-sectional view that shows an
input-capable liquid crystal display device according to a first
embodiment of the invention.
[0015] FIG. 2 is an equivalent circuit diagram of FIG. 1.
[0016] FIG. 3 is a plan configuration diagram that shows a
sub-pixel region.
[0017] FIG. 4 is a cross-sectional view that is taken along the
line IV-IV in FIG. 3.
[0018] FIG. 5 is a perspective view that shows a mobile personal
computer.
[0019] FIG. 6 is a cross-sectional view that shows an input-capable
liquid crystal display device according to a second embodiment of
the invention.
DETAILED DESCRIPTION
[0020] First Embodiment
[0021] A first embodiment of an input-capable display device
according to the invention will now be described with reference to
the accompanying drawings. Note that the scales of the drawings
used in the following description are appropriately changed in
order to make the components be recognizable. Here, FIG. 1 is a
schematic cross-sectional view that shows the input-capable liquid
crystal display device. FIG. 2 is an equivalent circuit diagram of
FIG. 1. FIG. 3 is a plan configuration diagram that shows a
subpixel region. FIG. 4 is a cross-sectional view that is taken
along the line IV-IV in FIG. 3.
[0022] Input-Capable Display Device
[0023] The input-capable liquid crystal display device
(input-capable display device) 1 is a transmissive color liquid
crystal display device, in which a single pixel is constituted of
three sub-pixels that output colored rays of R (red), G (green), B
(blue). Here, a display area that becomes a minimum unit for
forming display is termed as "sub-pixel region". Here, a display
area that becomes a minimum unit for forming display is termed as
"sub-pixel region".
[0024] First, the schematic configuration of the input-capable
liquid crystal display device 1 according to the present embodiment
will be described. The input-capable liquid crystal display device
1 according to the present embodiment, as shown in FIG. 1, includes
an element substrate (first substrate) 11, which is an active
matrix substrate, an opposite substrate (second substrate) 12 that
is opposed to the element substrate 11, and a liqu.id crystal layer
13 that is held between the element substrate 11 and the opposite
substrate 12. The input-capable liquid crystal display device 1 is
configured to irradiate illuminating light from the outer surface
side (the side away from the liquid crystal layer 13) of the
element substrate 11. In addition, the input-capable liquid crystal
display device 1 includes a seal material 14, which is
substantially rectangular and box-shaped in plan view, provided at
the outer peripheral portion of an opposed area in which the
element substrate 11 is opposed to the opposite substrate 12. By
this seal material, the element substrate 11 and the opposite
substrate 12 are adhered to each other. Then, an image display area
is formed inside the seal material 14 within the input-capable
liquid crystal display device 1. Furthermore, the input-capable
liquid crystal display device 1 includes a detection electrode 15
that is provided on the outer surface side {the side away from the
liquid crystal layer 13) of the opposite substrate 12, a polarizer
16 that is provided on the outer surface side of the element
substrate 11, a polarizer (dielectric film) 17 that is provided on
the outer surface side of the detection electrode 15, and a
detector 18 that detects a position of electrostatic capacitance
formed with the detection electrode 15 through the polarizer
17.
[0025] A plurality of sub-pixel regions are arranged in the image
display area of the input-capable liquid crystal display device 1
in a matrix, as shown in FIG. 2. In each of the plurality of
sub-pixel regions, a pixel electrode (first electrode) 21 and a TFT
(thin film transistor) element 22 that is used for switching the
control of the pixel electrode 21 are formed. In addition, in the
image display area, a plurality of data lines 23 and a plurality of
scanning lines 24 are arranged in a grid. The sources of the TFT
elements 22 are connected to the corresponding data lines 23, the
gates thereof are connected to the corresponding scanning lines 24,
and the drains thereof are connected to the corresponding pixel
electrodes 21.
[0026] The data lines 23 are configured to supply image signals S1,
S2, . . . Sn that are supplied from a driving circuit (not shown),
which is provided in the input-capable liquid crystal display
device 1, to the corresponding subpixel regions. Here, the data
lines 23 may be configured to supply the image signals S1 to Sn
sequentially in the order of lines or may be configured to supply
the image signals S1 to Sn in units of a plurality of the grouped
data lines 23 that are arranged adjacent to each other. The
scanning lines 24 are configured to supply scanning signals G1, G2,
. . . Gm, which are supplied from a driving circuit (not shown)
provided in the input-capable liquid crystal display device 1, to
the corresponding sub-pixel regions. Here, the scanning lines 24
supply the scanning signals G1 to Gm in a pulse-like manner in the
order of lines at a predetermined timing.
[0027] In addition, the input-capable liquid crystal display device
1 is configured so that, as the TFT element 22, which is a
switching element, is made into an on state only during a certain
period because of the input of the scanning signals G1 to Gm, the
image signals S1 to Sn supplied from the data lines 23 are written
to the pixel electrodes 21 at a predetermined timing. Then,
predetermined levels of image signals S1 to Sn that are written to
the liquid crystal through the pixel electrodes 21 are maintained
during a certain period between the pixel electrodes 21 and common
electrodes (second electrode) 43, which will be described
later.
[0028] A detailed configuration of the input-capable liquid crystal
display device 1 will now be described with reference to FIG. 3 and
FIG. 4. Note that the opposite substrate 12 is not shown in FIG. 3.
Note that the opposite substrate 12 is not shown in FIG. 3. In
addition, in FIG. 3, the long axis direction of the substantially
rectangular sub-pixel region in plan view is defined as X axis
direction and the short axis direction is defined as Y axis
direction. The element substrate 11, as shown in FIG. 4, includes a
substrate body 31, a base protection film 32, a gate insulating
film 33, a first interlayer insulating film 34, a second interlayer
insulating film 35, a third interlayer insulating film 36 and an
alignment layer 37. The substrate body 31 is formed of a
translucent material, such as glass, quartz or plastic, for
example. The base protection film 32, the gate insulating film 33 1
the first interlayer insulating film 34, the second interlayer
insulating film 35, the third interlayer insulating film 36 and the
alignment layer 37 are sequentially laminated on the inner surface
of the substrate body 31 (the side adjacent to the liquid crystal
layer 13). In addition, the element substrate 11 includes a
semiconductor layer 41, a scanning line 24, a data line 23, a
connection electrode 42, a common electrode 43, and a pixel
electrode 21. The semiconductor layer 41 is arranged on the inner
surface of the base protection film 32. The scanning line 24 is
arranged on the inner surface of the gate insulating film 33. The
data line 23 and the connection electrode 42 are arranged on the
inner surface of the first interlayer insulating film 34. The
common electrode 43 is arranged on the inner surface of the second
interlayer insulating film 35. The pixel electrode 21 is arranged
on the inner surface of the third interlayer insulating film
36.
[0029] The base protection film 32 is, for example, formed of a
translucent silicon oxide, such as SiO2 (oxide silicon), for
example, and covers the substrate body 31. Note that the material
of the base protection film 32 is not limited to SiO2, but it may
be formed of an insulating material, such as SiN (silicon nitride),
SiON (silicon oxynitride), or ceramics thin film. The gate
insulating film 33 is, for example, formed of a translucent
material, such as SiO2, for example, and is provided to cover the
semiconductor layer 41 that is formed on the base protection film
32. The first interlayer insulating film 34 is, for example, formed
of a translucent material, such as SiO2, and is provided to cover
the gate insulating film 33 and the scanning line 24 that are
formed on the gate insulating film 33. The second interlayer
insulating film 35 is, for example, formed of a translucent
material, such as acrylic, and is provided to cover the first
interlayer insulating film 34 and also cover the data line 23 and
the connection electrode 42 that are formed on the first interlayer
insulating film 34. The third interlayer insulating film 36 is, for
example, formed of a translucent material, such as SiN, and is
provided to cover the common electrode 43 that is formed on the
inner surface of the second interlayer insulating film 35. The
alignment layer 37 is, for example, formed of a resin material,
such as polyimide, and is provided to cover the pixel electrode 21
that is formed on the third interlayer insulating film 36. In
addition, an alignment process is treated on the surface of the
alignment layer 37 so that the short axis direction (Y axis
direction) of the sub-pixel region shown in FIG. 3 is made as an
alignment direction.
[0030] As shown in FIG. 3 and FIG. 4, the semiconductor layer 41
has a substantially L-shape in plan view and is formed to include
portion of an area that overlaps the scanning line 24 in plan view
through the gate insulating film 33. Then, a channel region 41a is
provided on an area of the semiconductor layer 41, which overlaps
the scanning line 24 in plan view through the gate insulating film
33. In addition, the semiconductor layer 41 includes a source
region 41b and a drain region 41c that are formed by injecting
impurity ion therein. Thus, the TFT element 22 is formed using the
semiconductor layer 41 as a main body. Note that the channel region
41a is formed by not injecting impurity ion into polysilicon. Here,
the semiconductor layer 41 may be formed as a LDD structure in
which a high concentration region that has a relatively high
impurity concentration in the source region and the drain region
and a low concentration (LDD (Lightly Doped Drain)) region that has
a relatively low impurity concentration are formed.
[0031] The scanning line 24 is arranged along the short axis
direction (Y axis direction) of the substantially rectangular
sub-pixel region in plan view. The scanning line 24 is, for
example, formed of a metal material, such as Al (aluminum). In
addition, portion of the scanning line 24, which is opposed to the
channel region 41a through the gate insulating film 33, functions
as the gate electrode. The data line 23 is arranged along the long
axis direction (X axis direction) of the sub-pixel region in plan
view. The data line 23 is, for example, formed of a metal material,
such as Al. In addition, the data line 23 is connected to the
source region 41b of the semiconductor layer 41 through a contact
hole H1 that extends through the gate insulating film 33 and the
first interlayer insulating film 34. That is, the data line 23
connects the TFT elements 22 that are arranged along the X axis
direction. The connection electrode 42 is connected to the drain
region 41c of the semiconductor layer 41 through a contact hole H2
that extends through the gate insulating film 33 and the first
interlayer insulating film 34.
[0032] The common electrode 43 is formed to cover the second
interlayer insulating film 35. The common electrode 43 is, for
example, formed of a translucent conductive material, such as ITO
(indium tin oxide). Then, an opening 43a is formed at a portion of
the common electrode 43, which is located in proximity to a contact
hole H3, which will be described later, that is used to conduct the
pixel electrode 21 with the connection electrode 42 in order to
ensure electrical insulation against the pixel electrode 21. In
addition, the common electrode 43 is, for example, applied with a
signal that switches periodically between a predetermined certain
voltage and 0 V, or applied with a signal that switches
periodically (every frame period or every field period) between a
first predetermined certain potential and a second predetermined
certain potential that is different from the first predetermined
certain potential, which are used for driving the liquid crystal
layer 13.
[0033] As shown in FIG. 3 and FIG. 4, the pixel electrode 21 has a
substantially ladder shape in plan view and is, for example, formed
of a translucent conductive material, such as ITO, as well as the
common electrode 43. Then, the pixel electrode 21 includes a
rectangular frame-shaped frame portion 21a in plan view and a
plurality of stripe portions 21b that extend in the substantially
short axis direction (Y axis direction) of the sub-pixel region and
are arranged at intervals in the long axis direction (X axis
direction) of the sub-pixel region.
[0034] The frame portion 21a is formed so that two pairs of stripe
electrodes are connected so as to form a substantially rectangular
frame shape in plan view. Two pairs of opposite sides respectively
extend along the long axis direction (X axis direction) and along
the short axis direction (Y axis direction). In addition, the frame
portion 21a is connected to the connection electrode 42 through the
contact hole H3 that extends through the second interlayer
insulating film 35 and the third interlayer insulating film 36. In
this way, the pixel electrode 21 is connected to the drain of the
TFT element 22. The stripe portions 21b are formed so as to be
parallel to each other. Both ends of each stripe portion 21b are
connected to the frame portion 21a at portions which extend along
the Y axis direction. In addition, the stripe portions 21b are
provided so that the extending directions of the stripe portions
21b are not parallel to the Y axis direction. That is, the
extending direction of each of the stripe portions 21b is formed so
that each strip portion 21b approaches the scanning line 24 as it
extends from one end adjacent to the data line 23 to the other end
away from the data line 23 in plan view. As described above, the
input-capable liquid crystal display device 1 is configured so that
a voltage is applied between the stripe portions 21b and the common
electrode 43 and then the liquid crystal is driven by an electric
field (lateral electric field) that is generated in a direction in
which the plane of the substrate extends. In this way, the pixel
electrode 21 and the common electrode 43 constitute a FFS
(Fringe-Field Switching) mode electrode structure.
[0035] On the other hand, as shown in FIG. 4, the opposite
substrate 12 includes a substrate body 51, a shield electrode
(shield conductor) 52, a light shielding film 53, a color filter
layer 54 and an alignment layer 55. The substrate body 51 is, for
example, formed of a translucent material, such as glass, quartz or
plastic. The shield electrode 52, the light shielding film 53, the
color filter layer 54 and the alignment layer 55 are sequentially
laminated on the inner surface of the substrate body 51 (the side
adjacent to the liquid crystal layer 13). The shield electrode 52
is formed entirely on the inner surface of the opposite substrate
12. The shield electrode 52 is, for example, formed of a
translucent conductive rr1aterial, such as ITO. Then, the shield
electrode 52 overlaps the pixel electrode 21 and the common
electrode 43 through the liquid crystal layer 13. Here, the shield
electrode 52 has a sheet resistance of 1 k.OMEGA./sq or below, for
example. In addition, the shield electrode 52 is ensured to be
conducted with a wiring portion (not shown), which is provided on
the element substrate 11 through an inter-substrate conductive
material (not shown), which is formed of a conductive material at
the end portion of the opposite substrate 12. Then, the shield
electrode 52 exhibits a substantially constant potential through
this wiring portion.
[0036] The light shielding film 53 is formed in a substantially
grid in plan view in a region in which, of the surface of the
shield electrode 52, the edge portion of the sub-pixel region
overlaps the TFT element 22, the data line 23 and the scanning line
24 through the liquid crystal layer 13 in plan view. The light
shielding film 53 edges the subpixel region. In addition, the color
filter layer 54 is arranged at a position corresponding to each
sub-pixel region so as to cover the light shielding film 53. The
color filter layer 54 is, for example, formed of acrylic and
contains a color material corresponding to the color the sub-pixel
region displays. The alignment layer 55 is, for example, formed of
a translucent resin material, such as polyimide and is provided so
as to cover the color filter layer 54. Then, a rubbing process in
the same direction as the alignment direction of the alignment
layer 55 is treated on the inner surface of the alignment layer
55.
[0037] Because the alignment process in which the short axis
direction (Y axis direction) of the sub-pixel region is defined as
an alignment direction is performed for the alignment layers 37,
55, liquid crystal molecules that forms the liquid crystal layer 13
are aligned horizontally along the Y axis direction when no voltage
is applied between the pixel electrode 21 and the common electrode
43, that is, in an off state. In addition, liquid crystal molecules
are aligned along the direction perpendicular to the extending
directions of the stripe portions 21b when voltage is applied
between the pixel electrode 21 and the common electrode 43, that
is, in an on state. Thus, in the liquid crystal layer 13, by using
a birefringent characteristic on the basis of a difference in
alignment state of liquid crystal molecules between an off state
and an on state, a phase difference is given to light that is
transmitted through the liquid crystal layer 13.
[0038] The detection electrode 15 is formed entirely over the outer
surface of the opposite substrate 12. The detection electrode 15
is, for example, formed of a translucent conductive material, such
as ITO. In addition, terminal portions (not shown) are provided at
respective four corners of the substantially rectangular detection
electrode 15 in plan view. The terminal portions are supplied with
a detection signal from the detector 18.
[0039] The polarizer 16 is, for example, formed so that a film
formed by using a dielectric material of polyvinyl alcohol (PVA) as
a base. Then, the polarizer 16 is provided so that the polarization
axis thereof extends along the long axis direction (the X axis
direction shown in FIG. 2) of the sub-pixel region. The polarizer
17 as well as the polarizer 16 is formed so that a film of
polyvinyl alcohol (PVA) is used as a base. Note that a protection
film (not shown) that protects the polarizer 17 may be provided on
the outer surface side of the polarizer 17. Then, the polarizer 17
is provided so that the polarization axis thereof extends along the
short axis direction (the Y axis direction shown in FIG. 2) of the
sub-pixel region. Thus, the polarizers 16, 17 are provided so that
their polarization axes are substantially perpendicular to each
other. Here, a quarter wavelength plate may be arranged on the
inner side of the polarizer 17. By arranging the quarter wavelength
plate, it is possible to prevent ambient light that enters from the
outer surface of the polarizer 17 from being reflected on the
element substrate 11 to exit outside. Note that, in coordination
with the quarter wavelength plate, the polarization axis of the
polarizer 17 is changed appropriately. In addition, an optical
compensation film (not shown) may be arranged on one of or both of
the inner side of the polarizers 16, 17. By arranging the optical
compensation film, it is possible to compensate for a phase
difference of the liquid crystal layer 13 when the input-capable
liquid crystal display device 1 is viewed obliquely. Also, it is
possible to increase the contrast by reducing a leakage of light.
The optical compensation film employs a medium that combines a
negative uniaxial medium and a positive uniaxial medium or a
biaxial medium having refractive indices of nx>nz>ny for
respective directions.
[0040] The detector 18 is configured to generate a uniform electric
field within the plane of the detection electrode 15 by applying
the terminal portions provided on the detection electrode 15 with
alternating voltages having the same phase and same potentials. In
addition, the detector 18 is configured to detect a position of
contact of a finger, or the like, through a measured value of the
magnitude of electric current that flows through an electrostatic
capacitance formed with the detection electrode 15 through the
polarizer 17.
[0041] Operation of Input-capable Liquid Crystal Display Device
[0042] The operation of the above configured input-capable liquid
crystal display device 1 will now be described. Light entering from
the outer surface side of the element substrate 11 is converted by
the polarizer 16 to a linearly polarized light that is parallel to
the long axis direction (X axis direction shown in FIG. 3) of the
sub-pixel region and then enters the liquid crystal layer 13. Here,
when it is in an off state, the linearly polarized light that has
entered the liquid crystal layer 13, owing to the liquid crystal
layer 13, exits from the liquid crystal layer 13 in the same
polarized state as it was when entered the liquid crystal layer 13.
Then, this linearly polarized light, because its polarized
direction is perpendicular to the polarization axis of the
polarizer 17, is blocked by the polarizer 17 and/hence, the
sub-pixel region appears to be a dark display. On the other hand,
when it is in an on state, the linear light that has entered the
liquid crystal layer 13 is given a predetermined phase difference
(1/2 wavelength) by the liquid crystal layer 13 and is converted to
a linearly polarized light that has a polarized direction
perpendicular to the polarized direction when it entered the liquid
crystal layer 13 and then exits from the liquid crystal layer 13.
Then, this linearly polarized light, because its polarized
direction is parallel to the polarization axis of the polarizer 17,
is transmitted through the polarizer 17 to be viewed as a display
light and, hence, the sub-pixel region appears to be a bright
display.
[0043] At this time, when image signals S1 to Sn are supplied from
the data lines 23 to the liquid crystal layer 13, electric fields
are generated between the pixel electrodes 21 and the corrunon
electrodes 43 that are formed on the element substrate 11. Here, a
sufficient gap is formed between the pixel electrodes 21 and common
electrodes 43 and the shield electrode 52 that is provided in the
opposite substrate 12. Therefore/the strength of electric fields
that become noise, traveling from the pixel electrodes 21 and
common electrodes 43 toward the shield electrode 52 due to the
supply of the image signals S1 to Sn becomes small as compared with
a so-called vertical electric field mode electrode structure, such
as a TN mode, for example, in which the common electrode is
provided in the opposite substrate. Thus, the electric fields that
travel from the pixel electrodes 21 and common electrodes 43 toward
the detection electrode 15 are effectively blocked by the shield
electrode 52.
[0044] Then, when user's finger touches the polarizer 17 in a state
where a uniform alternating voltage is applied within a plane of
the detection electrode 15, an electrostatic capacitance is formed
between the detection electrode 15 and the finger through the
polarizer 17. Thus, electric current flows from the terminal
portions provided on the detection electrode 15 through the
electrostatic capacitance. The detector 18 detects the magnitude of
electric current that flows by the formation of electrostatic
capacitance through, for example, the four corners of the detection
region, respectively, and then detects a position of contact of the
finger, or the like, from those pieces of information. Here,
because the substrate body 51, and the like, is provided between
the detection electrode 15 and the shield electrode 52 and a
sufficient gap is formed therebetween, a capacitance component is
prevented to be formed between the detection electrode 15 and the
shield electrode 52.
[0045] Electronic Apparatus
[0046] The above configured input-capable liquid crystal display
device 1 is used as a display portion 101 of a mobile personal
computer 100, as shown in FIG. 5, for example. This mobile personal
computer 100 includes the display portion 101 and a main body
portion 103 that has a keyboard 102.
[0047] As described above, according to the input-capable liquid
crystal display device 1 in the present embodiment, by providing
the opposite substrate 12 with the shield electrode 52, an
influence of noise generated while driving the liquid crystal layer
13 is suppressed without excessively thickening the opposite
substrate 12 and without using a complex system, thus improving the
accuracy of detection of a position of contact on the display
surface. Furthermore, a sufficient distance is ensured between the
pixel electrodes 21 and common electrodes 43 and the shield
electrode 52, so that an influence of noise generated while driving
the liquid crystal layer 13 is small as compared with the case
where a vertical electric field mode electrode structure is
employed. Thus, the shield electrode 52 effectively blocks the
noise. Then, because the shield electrode 52 and the detection
electrode 15 are sufficiently spaced apart from each other, no
capacitance component is formed between the shield electrode 52 and
the detection electrode 15. Moreover, the shield electrode 52 is
formed of a translucent conductive material, such as ITO, and the
shield electrode 52 may be formed in a planar shape, so that it is
possible to reliably block a noise. In addition, because the
polarizer 17 is formed by using a dielectric material, the number
of components is reduced.
[0048] Second Embodiment
[0049] A second embodiment of an input-capable liquid crystal
display device according to the invention will now be described
with reference to the drawings. Here, FIG. 6 is a cross-sectional
view that shows a sub pixel region. Note that, in the present
embodiment, because the configuration of the sub-pixel region
differs from that of the first embodiment, this point will be
specifically described. The same reference numerals are assigned to
the components described in the above embodiment, and a description
thereof is omitted.
[0050] In the input-capable liquid crystal display device 110, as
shown in FIG. 6, a light shielding film (shield conductor) 112 that
is provided in an opposite substrate 111 is formed of a conductive
material and also serves as a shielding conductor. That is, the
opposite substrate 111 includes the substrate body 51, the shield
electrode 112, the color filter layer 54 and the alignment layer
55. The light shielding film 112, the color filter layer 54 and the
alignment layer 55 are sequentially laminated on the inner surface
of the substrate body 51. The light shielding film 112 is, for
example, formed of a metal material, such as Cr (chrome), having a
light absorption characteristic or a conductive material, having a
light absorption characteristic, that is formed by dispersing
carbon black in a resin. Then, the light shielding film 112 is
connected to the wiring portion provided the element substrate 11
through the above described inter-substrate conductive member at
the end portion of the opposite substrate 12. Thus, an electric
potential of the light shielding film 112 is controlled to a
certain potential. Note that the light shielding film 112 has an
opening portion that is formed in correspondence with the sub-pixel
region; however, an electric field that is generated due to signals
supplied to the pixel electrodes 21 so as to be directed from the
pixel electrodes 21 and common electrodes 43 toward the detection
electrode 15 can be blocked sufficiently.
[0051] As described above, even with the input-capable liquid
crystal display device 110 in the present embodiment, the same
function and advantageous effects as those of the above described
embodiment are obtained; however, because the light shielding film
112 also serves as a shield conductor, the number of components is
reduced and thickness of the opposite substrate 111 is reduced.
[0052] Note that the invention is not limited to the embodiments
described above, but it may be modified into various forms without
departing from the spirit of the invention. For example, the
potential of the shield electrode is fixed by conducting the shield
electrode to the element substrate through the inter-substrate
conductive member provided at the end portion of the opposite
substrate; however, another method may be employed as long as the
potential of the shield electrode is fixed. In addition, the
polarizer provided on the outer surface side of the opposite
substrate constitutes a dielectric film; however, a dielectric film
may be separately provided in addition to the polarizer.
[0053] In addition, the input-capable liquid crystal display device
is configured so that the pixel electrodes and the common
electrodes have the FFS mode electrode structure; however, it may
employ another electrode structure that uses a so-called horizontal
electric field mode, such as IPS (In-Plane Switching) mode. Then,
the input-capable liquid crystal display device is a transmissive
liquid crystal device; however, it may be a configuration of
another liquid crystal display device, such as a reflective liquid
crystal display device or a transflective liquid crystal display
device. Furthermore, it is not limited to a color liquid crystal
display device.
[0054] Moreover, the electronic apparatus that is provided with the
input-capable liquid crystal display device is not limited to the
mobile personal computer, but it may be another electronic
apparatus, such as a cellular phone, a PDA (Personal Digital
Assistants), a personal computer, a laptop personal computer f a
workstation, digital still camera, an on-board monitor, a car
navigation system, a heads-up display, digital video camera, a
television; a viewfinder type or direct view type video tape
recorder a pager, a personal organizer, an electronic calculator,
an electronic book; a projector, a word processor, a video
telephone, a POS terminal, and devices provided with a touch panel
display.
[0055] It should be understood that various changes and
modifications to the presently preferred embodiments described
herein will be apparent to those skilled in the art. Such changes
and modifications can be made without departing from the spirit and
scope of the present subject matter and without diminishing its
intended advantages. It is therefore intended that such changes and
modifications be covered by the appended claims.
* * * * *