U.S. patent application number 15/170029 was filed with the patent office on 2016-09-22 for liquid crystal display device.
The applicant listed for this patent is NLT Technologies, Ltd.. Invention is credited to Shinichi NISHIDA, Naoyuki TAGUCHI, Takahiko WATANABE.
Application Number | 20160274424 15/170029 |
Document ID | / |
Family ID | 49134475 |
Filed Date | 2016-09-22 |
United States Patent
Application |
20160274424 |
Kind Code |
A1 |
NISHIDA; Shinichi ; et
al. |
September 22, 2016 |
LIQUID CRYSTAL DISPLAY DEVICE
Abstract
A transverse electric field-type liquid crystal display device
displays by rotating homogeneous-aligned liquid crystals by a
transverse electric field substantially parallel to a substrate,
applied across a pixel electrode and a common electrode, assuring
sufficient storage capacitance while enlarging the area of driving
the liquid crystal molecules in a sub pixel. A source pixel
electrode connected to a source electrode extends along the data
line, a storage capacitance electrode formed by the same layer as
the data line is formed above an adjacent scan line so as to
overlap the adjacent scan line, the source pixel electrode is
disposed so as to be connected to the storage capacitance electrode
and a pixel along one side, an interlayer film is formed over the
source pixel electrode, and a pixel electrode and a common
electrode formed by a transparent conductive film are formed over
the interlayer film.
Inventors: |
NISHIDA; Shinichi;
(Kanagawa, JP) ; TAGUCHI; Naoyuki; (Kanagawa,
JP) ; WATANABE; Takahiko; (Kanagawa, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
NLT Technologies, Ltd. |
Kanagawa |
|
JP |
|
|
Family ID: |
49134475 |
Appl. No.: |
15/170029 |
Filed: |
June 1, 2016 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
13826388 |
Mar 14, 2013 |
9389464 |
|
|
15170029 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G02F 1/133528 20130101;
G02F 1/1368 20130101; G02F 2001/133519 20130101; G02F 2001/134345
20130101; G02F 1/13439 20130101; G02F 1/133345 20130101; G02F
1/136213 20130101; G02F 1/134363 20130101; G02F 2001/133302
20130101; G02F 1/133784 20130101; G02F 1/136286 20130101; G02F
1/13394 20130101; G02F 1/133514 20130101; G02F 1/133516 20130101;
G02F 1/1341 20130101; G02F 1/133753 20130101; G02F 1/134336
20130101; G02F 1/133512 20130101; G02F 2001/133531 20130101 |
International
Class: |
G02F 1/1343 20060101
G02F001/1343; G02F 1/1337 20060101 G02F001/1337; G02F 1/1368
20060101 G02F001/1368; G02F 1/1333 20060101 G02F001/1333; G02F
1/1339 20060101 G02F001/1339; G02F 1/1362 20060101 G02F001/1362;
G02F 1/1335 20060101 G02F001/1335; G02F 1/1341 20060101
G02F001/1341 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 14, 2012 |
JP |
2012-058037 |
Claims
1. A liquid crystal display device of a transverse electric field
type performing display by rotating horizontal-aligned liquid
crystals by a transverse electric field which is applied across a
pixel electrode and a common electrode and is substantially
parallel to a substrate, comprising: a substrate having a plurality
of data lines disposed in parallel and a plurality of scan lines
disposed substantially perpendicular to the data lines and in
parallel to one another, and having thin film transistors
corresponding to respective sub pixels aligned in a matrix
surrounded by the data lines and the scan lines and disposed around
intersections between the data lines and the scan lines; an
electric potential supply line extending along the data line in the
sub pixel region and connected to a source electrode of the thin
film transistor; and a storage capacitance electrode continued to
the electric potential supply line, disposed above the scan line
via an insulating layer, and generating capacitance between the
scan line and itself, wherein the pixel electrode has pixel
electrode first parts and a pixel electrode second part, the pixel
electrode first parts are disposed in a layer upper than the
electric potential supply line in the sub pixel region and linearly
formed in substantially parallel to the scan line, the pixel
electrode second part is continued to the pixel electrode first
parts, formed in parallel to the data line, and connected to the
electric potential supply line, the common electrode has common
electrode first parts and a common electrode second part, the
common electrode first parts are aligned opposed to the pixel
electrode first parts, apart from the pixel electrode first parts
at same distance, and generate an electric field substantially
parallel to the substrate, and the common electrode second part is
continued to the common electrode first parts and provided above
the storage capacitance electrode via an insulating film.
2. The liquid crystal display device according to claim 1, wherein
the electric potential supply line and the storage capacitance
electrode are continued and formed in a substantially L shape
around an intersection of the data line and the scan line.
3. The liquid crystal display device according to claim 1, wherein
the storage capacitance electrode covers the scan line, and the
common electrode second part covers the storage capacitance
electrode.
4. The liquid crystal display device according to claim 1, wherein
an interval of the plurality of data lines is set to be larger than
an interval of the plurality of scan lines.
5. A liquid crystal display device of a transverse electric field
type performing display by rotating horizontal-aligned liquid
crystals by a transverse electric field which is applied across a
pixel electrode and a common electrode and is substantially
parallel to a substrate, comprising: a substrate having a plurality
of data lines disposed in parallel and a plurality of scan lines
disposed substantially perpendicular to the data lines and in
parallel to one another, and having thin film transistors
corresponding to respective sub pixels aligned in a matrix
surrounded by the data lines and the scan lines and disposed around
intersections between the data lines and the scan lines; an
electric potential supply line extending along the data line in the
sub pixel region and connected to a source electrode of the thin
film transistor; and a storage capacitance electrode continued to
the electric potential supply line, disposed above the scan line
via an insulating layer, and generating capacitance between the
scan line and itself, wherein the pixel electrode expands in a
plane shape above the electric potential supply line within the sub
pixel region and is connected to the electric potential supply
line, the common electrode has common electrode first parts and a
common electrode second part, the common electrode first parts are
aligned facing the pixel electrode above the pixel electrode via an
insulating layer and generate, between the pixel electrode and
themselves, an electric field substantially parallel to the
substrate, and the common electrode second part is continued to the
common electrode first parts and provided above the storage
capacitance electrode via an insulating film.
6. The liquid crystal display device according to claim 5, wherein
the electric potential supply line and the storage capacitance
electrode are continued and formed in a substantially L shape
around an intersection of the data line and the scan line.
7. The liquid crystal display device according to claim 5, wherein
the storage capacitance electrode covers the scan line, and the
common electrode second part covers the storage capacitance
electrode.
8. The liquid crystal display device according to claim 5, wherein
an interval of the plurality of data lines is set to be larger than
an interval of the plurality of scan lines.
9. A liquid crystal display device of a transverse electric field
type performing display by rotating horizontal-aligned liquid
crystals by a transverse electric field which is applied across a
pixel electrode and a common electrode and is substantially
parallel to a substrate, comprising: a substrate having a plurality
of data lines disposed in parallel and a plurality of scan lines
disposed substantially perpendicular to the data lines and in
parallel to one another, and having thin film transistors
corresponding to respective sub pixels aligned in a matrix
surrounded by the data lines and the scan lines and disposed around
intersections between the data lines and the scan lines; an
electric potential supply line extending along the data line in the
sub pixel region and connected to a source electrode of the thin
film transistor; and a storage capacitance electrode continued to
the electric potential supply line, disposed above the scan line
via an insulating layer, and generating capacitance between the
scan line and itself, wherein the common electrode expands in a
plane shape above the electric potential supply line within the sub
pixel region and is connected to the electric potential supply
line, the pixel electrode has pixel electrode first parts and a
pixel electrode second part, the pixel electrode first parts are
aligned facing the common electrode above the common electrode via
the insulating layer and generate, between the common electrode and
themselves, an electric field substantially parallel to the
substrate, and the pixel electrode second part is continued to the
pixel electrode first parts and provided above the electric
potential supply line via an insulating film.
10. The liquid crystal display device according to claim 9, wherein
the electric potential supply line and the storage capacitance
electrode are continued and formed in a substantially L shape
around an intersection of the data line and the scan line.
11. The liquid crystal display device according to claim 9, wherein
an interval of the plurality of data lines is set to be larger than
an interval of the plurality of scan lines.
Description
TECHNICAL FIELD
[0001] The present invention relates to a liquid crystal display
device and, more particularly, to an active-matrix-type liquid
crystal display device in which liquid crystal molecules are driven
with an electric field substantially perpendicular to a thin film
transistor substrate.
BACKGROUND ART
[0002] A liquid crystal display device of a TN (Twisted Nematic)
type being widely used has high contrast but, on the other hand,
has a problem of high visual angle dependence since the molecular
axis of the liquid crystal rises due to the vertical electric
field. Since demand for a large-sized monitor of a TV or the like
is increasing in recent years, a so-called
transverse-electric-field-type liquid crystal panel such as the IPS
(In-Plane Switching) type or FFS type is being spread, in which an
electric field substantially parallel to a substrate for which thin
film transistors (hereinafter, called TFTs) are provided is applied
to liquid crystal molecules to drive the molecules. A
transverse-electric-field-type liquid crystal display panel of, for
example, the IPS type has a plurality of pixel electrodes
substantially parallel to a data line or scan line on a substrate,
and a common electrode which is paired with the pixel electrodes.
By an electric field substantially parallel to the substrate formed
between the pixel electrodes and the common electrode, the liquid
crystal molecules are turned in a plane parallel to the substrate,
thereby controlling display. By driving the liquid crystal
molecules in this manner, the visual angle dependency with respect
to the rise angle of the molecular axis is eliminated. The visual
angle characteristic is more advantageous as compared with that of
the TN type.
[0003] In such a liquid crystal display device, it is preferable to
drive liquid crystal molecules in a wider range. For example,
patent literature 1 discloses a technique of driving a liquid
crystal material in a wider area, provided as a layer between a
substrate for which a TFT is provided and an opposed substrate
which is opposed to the substrate and has a color filter. In the
patent literature 1, for example, a technique of shortening the
interval of neighboring pixel electrodes to be smaller than the
limit determined by the conventional process margin and preventing
short-circuit of the neighboring pixel electrodes. Patent
literature 2 discloses a liquid crystal display device of a
transverse electric field type with improved brightness by
disposing a pixel electrode and an opposed electrode substantially
parallel to a scan line, making a data line and a source pixel
electrode adjacent to each other, and forming a storage capacitance
electrode on the scan line (FIG. 10). On the other hand, patent
literature 3 discloses s liquid crystal display device of the
transverse electric field type with improved aperture ratio in
which a scan line and a data line are covered with a common
electrode via an interlayer insulating film.
Patent Literature 1: Japanese Unexamined Patent Application
Publication No. 2004-212436
Patent Literature 2: Japanese Unexamined Patent Application
Publication No. 2002-122876
Patent Literature 3: Japanese Unexamined Patent Application
Publication No. 2004-062145
SUMMARY OF THE INVENTION
[0004] In the patent literature 1, to generate an electric field
substantially parallel to a substrate, a pixel electrode and a
common electrode have to be disposed on the substrate. For example,
between a data line and the pixel electrode, a clearance has to be
provided to prevent a delay in transmission of a data signal. The
electrode has to be disposed apart from the data line for the
clearance, the range of driving the liquid crystal molecules cannot
be widened in the sub pixel, and it causes a problem that the
aperture ratio cannot be increased.
[0005] In the patent literature 2, in a liquid crystal display
device of a transverse electric field type, between a data line and
a pixel electrode, a clearance has to be provided to prevent a
delay in transmission of a data signal. For example, in the liquid
crystal display device, the data line and the pixel electrode are
in the same layer, so that the connecting part of the pixel
electrode has to be disposed apart from the data line, and there is
a problem such that the range of driving the liquid crystal
molecules cannot be widened in the sub pixel.
[0006] On the other hand, in the patent literature 3, the storage
capacitance is generated between the pixel electrode and the common
electrode line and between the pixel electrode and the common
electrode in the liquid crystal display device. Since the storage
capacitance is generated on the short side of a pixel in structure,
large area cannot be assured, and there is a problem such that
sufficient storage capacitance cannot be assured.
[0007] The present invention has been made in consideration of the
above circumstances and an object of the invention is to
sufficiently assure storage capacitance while enlarging an area of
driving liquid crystal molecules in a sub pixel.
[0008] To solve the problem, the present invention provides a
liquid crystal display device of a transverse electric field type
performing display by rotating horizontal-aligned liquid crystals
by a transverse electric field which is applied across a pixel
electrode and a common electrode and is substantially parallel to a
substrate, including: a substrate having a plurality of data lines
disposed in parallel and a plurality of scan lines disposed
substantially perpendicular to the data lines and in parallel to
one another, and having thin film transistors corresponding to
respective sub pixels aligned in a matrix surrounded by the data
lines and the scan lines and disposed around intersections between
the data lines and the scan lines; an electric potential supply
line extending along the data line in a sub pixel region and
connected to a source electrode of the thin film transistor; and a
storage capacitance electrode continued to the electric potential
supply line, disposed above the scan line via an insulating layer,
and generating capacitance between the scan line and itself. The
pixel electrode has pixel electrode first parts and a pixel
electrode second part, the pixel electrode first parts are disposed
in a layer upper than the electric potential supply line in the sub
pixel region and linearly formed in substantially parallel to the
scan line, the pixel electrode second part is continued to the
pixel electrode first parts, formed in parallel to the data line,
and connected to the electric potential supply line, the common
electrode has common electrode first parts and a common electrode
second part, the common electrode first parts are aligned opposed
to the pixel electrode first parts, apart from the pixel electrode
first parts at same distance, and generate an electric field
substantially parallel to the substrate, and the common electrode
second part is continued to the common electrode first parts and
provided above the storage capacitance electrode via an insulating
film.
[0009] The present invention also provides a liquid crystal display
device of a transverse electric field type performing display by
rotating horizontal-aligned liquid crystals by a transverse
electric field which is applied across a pixel electrode and a
common electrode and is substantially parallel to a substrate,
including: a substrate having a plurality of data lines disposed in
parallel and a plurality of scan lines disposed substantially
perpendicular to the data lines and in parallel to one another, and
having thin film transistors corresponding to respective sub pixels
aligned in a matrix surrounded by the data lines and the scan lines
and disposed around intersections between the data lines and the
scan lines; an electric potential supply line extending along the
data line in a sub pixel region and connected to a source electrode
of the thin film transistor; and a storage capacitance electrode
continued to the electric potential supply line, disposed above the
scan line via an insulating layer, and generating capacitance
between the scan line and itself. The pixel electrode expands in a
plane shape above the electric potential supply line within the sub
pixel region and is connected to the electric potential supply
line, the common electrode has common electrode first parts and a
common electrode second part, the common electrode first parts are
aligned facing the pixel electrode above the pixel electrode via an
insulating layer and generate, between the pixel electrode and
themselves, an electric field substantially parallel to the
substrate, and the common electrode second part is continued to the
common electrode first parts and provided above the storage
capacitance electrode via an insulating film.
[0010] Further, the present invention provides a liquid crystal
display device of a transverse electric field type performing
display by rotating horizontal-aligned liquid crystals by a
transverse electric field which is applied across a pixel electrode
and a common electrode and is substantially parallel to a
substrate, including: a substrate having a plurality of data lines
disposed in parallel and a plurality of scan lines disposed
substantially perpendicular to the data lines and in parallel to
one another, and having thin film transistors corresponding to
respective sub pixels aligned in a matrix surrounded by the data
lines and the scan lines and disposed around intersections between
the data lines and the scan lines; an electric potential supply
line extending along the data line in the sub pixel region and
connected to a source electrode of the thin film transistor; and a
storage capacitance electrode continued to the electric potential
supply line, disposed above the scan line via an insulating layer,
and generating capacitance between the scan line and itself. The
common electrode expands in a plane shape above the electric
potential supply line in the sub pixel region and is connected to
the electric potential supply line, the pixel electrode has pixel
electrode first parts and a pixel electrode second part, the pixel
electrode first parts are aligned facing the common electrode above
the common electrode via the insulating layer and generate, between
the common electrode and themselves, an electric field
substantially parallel to the substrate, and the pixel electrode
second part is continued to the pixel electrode first parts and
provided above the electric potential supply line via an insulating
film.
[0011] According to the present invention, when viewed from a
direction perpendicular to the substrate, the pixel electrode or
the common electrode can be disposed closer to the data line side,
and while generating an electric field for driving liquid crystal
molecules more widely in the sub pixel, the storage capacitance can
be sufficiently assured.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] FIG. 1 is a plan view illustrating the configuration of one
sub pixel in a liquid crystal display device as a first embodiment
of the present invention.
[0013] FIG. 2 is a cross section taken along line A-A' of FIG. 1,
illustrating the liquid crystal display device as the first
embodiment of the invention.
[0014] FIG. 3 is a cross section of a substrate, taken along a
plane substantially perpendicular to the extension direction of the
data line in the liquid crystal display device as the first
embodiment of the invention.
[0015] FIG. 4 is an explanatory diagram illustrating a mode of
arranging three sub pixels of FIG. 1 in the liquid crystal display
device as the first embodiment of the invention.
[0016] FIG. 5 is a plan view illustrating the configuration of one
sub pixel in a liquid crystal display device as a second embodiment
of the present invention.
[0017] FIG. 6 is a cross section taken along line A-A' in FIG. 5 of
the liquid crystal display device as the second embodiment of the
present invention.
[0018] FIG. 7 is a plan view illustrating the configuration of one
sub pixel in a liquid crystal display device as a third embodiment
of the present invention.
[0019] FIG. 8 is a cross section taken along line A-A' of FIG. 7,
of the liquid crystal display device as the third embodiment of the
present invention.
[0020] FIG. 9 is a cross section of a substrate, taken along plane
perpendicular to the extension direction of a data line in the
liquid crystal display device as the third embodiment of the
present invention.
[0021] FIG. 10 is a plan view of a conventional liquid crystal
display device.
DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION
[0022] Embodiments of the present invention will be described.
First Embodiment
[0023] As illustrated in FIG. 1, in a liquid crystal display
device, a plurality of data lines 1 are disposed in parallel to one
another on a transparent substrate (first substrate). A plurality
of scan lines 2 are disposed substantially perpendicular to the
data lines 1. By the plurality of data lines 1 and the scan lines
2, a plurality of sub pixel regions arranged in a matrix are
defined.
[0024] A gate electrode is provided on the scan line 2 near a part
crossing the data line 1, and the drain electrode is connected from
the data line 1 crossing the scan line 2. With such a structure, a
thin film transistor can be formed near the crossing part of the
data line 1 and the scan line 2.
[0025] On one of the sides of the data line 1, a source pixel
electrode (an electric potential supply line connected to the
source electrode) is disposed along the data line 1, and the source
electrode of the TFT is connected to the source pixel electrode
[0026] Pixel electrodes are disposed in a layer upper than the
source pixel electrode 9 and formed in a comb-teeth shape.
[0027] For example, the pixel electrode is constructed by a
plurality of first parts 3 (first parts of a pixel electrode)
substantially parallel to the scan lines, and a second part 4 (a
second part of the pixel electrode) continued to the first parts
3.
[0028] In correspondence to the pixel electrode, a common electrode
also has a plurality of first parts 5 (first parts of the common
electrode) substantially parallel to the scan lines, and third and
second parts 7 and 6 (third and second parts of a common electrode)
continued to the first parts 5.
[0029] The first parts 5 of the common electrode and the first
parts 3 of the pixel electrode are disposed at predetermined
intervals and can generate an electric field substantially parallel
to the substrate.
[0030] The pixel of the first embodiment illustrated in FIGS. 1 and
2 will be described in detail in fabricating order.
[0031] First, on a glass substrate as a first insulating substrate
12, the scan line 2 is formed by a first metal layer made by 2500 A
of Cr.
[0032] As a gate insulating film 13, 5000 A of SiNx and a thin film
semiconductor layer made of 2000 A of a-Si and 500 A of n-a-Si are
formed. A thin film semiconductor layer 10 is patterned while
leaving only a TFT part provided as a switching element of the
pixel. By a second metal layer made by 2500 A of Cr, the data line
1, source/drain electrodes of the TFT, the source pixel electrode 9
connected to the source electrode of the TFT, and a storage
capacitance electrode 8 are formed.
[0033] Using the source/drain electrodes of the TFT as a mask,
n-a-Si in the TFT channel part is removed.
[0034] 6000 A of SiNx is formed as a protection insulating film 14,
and a through hole 25 for connecting the pixel electrode is
formed.
[0035] On the protection insulating film 14, a pattern is formed by
a transparent electrode made by 800 A of ITO, which is made of the
first part 3 of the pixel electrode, the second part 4 connecting
the first parts of the pixel electrodes, the first part 5 of the
common electrode, the second part 6 of the common electrode which
shields the data line, and the third part 7 of the common electrode
which shields the data line. The pixel electrode made by ITO is
connected to the source pixel electrode 9 formed by the second
metal layer via the through hole 25 in the second part 4.
[0036] A TFT array is formed according to the above-described
method.
[0037] Subsequently, a method of manufacturing a color filter
substrate will be described. On the back face of a second
transparent insulating substrate 22, 200 A of an ITO film 23 is
formed. A black matrix 34 is formed on the surface and, after that,
a pattern is formed in order of a green (G) layer 19, a red (R)
layer 20, and a blue (B) layer 21. Further, an overcoat layer 18 is
formed and, on the overcoat layer 18, a pillar spacer 35 is
formed.
[0038] Alignment films 15 and 16 are formed on the surface of the
array substrate and the surface of the color filter substrate
fabricated as described above, and rubbing process is performed in
the direction of 32. The substrates are adhered to each other, a
liquid crystal material is injected in the space between the
substrates, and the resultant is sealed. Liquid crystals 17 are
aligned in the direction of an initial alignment 32 of the liquid
crystals.
[0039] Further, on the outer sides of the glass substrates on both
sides, polarizers 11 and 24 are adhered so that their polarization
axes are orthogonal to each other. The direction of the absorption
axis of the incident-side polarizer on the TFT array substrate side
is matched with the direction of the initial alignment of the
liquid crystals.
[0040] By providing the liquid crystal display panel fabricated as
described above with a backlight and a drive circuit, an active
matrix liquid crystal display device of the transverse electric
field type of the first embodiment is completed.
[0041] The first part 3 of the pixel electrode and the first part 5
of the common electrode constructing the comb-shaped electrode, and
the second part 6 of the common electrode shielding the scan line
are formed substantially in parallel to one another and are bent in
a center part of the pixel. The right half of the first part 3 of
the pixel electrode tilts only by .theta. in the clockwise
direction from the liquid crystal alignment direction, and the
lower part of the left half tilts only by -.theta..
[0042] Since the scan line 2 and the pixel electrodes 3 and the
common electrodes 5 constructing the comb-shaped electrode
extending in the extension direction of the scan line 2 are bent
symmetrically with respect to the liquid crystal alignment
direction, the electric field in the direction turned from the
perpendicular direction (the extension direction of the data line)
only by .theta. in the clockwise direction is applied on the right
half side in the diagram of the pixel, and the electric field in
the direction turned from the perpendicular direction only by
.theta. in the counterclockwise direction is applied on the left
half side in the diagram of the pixel.
[0043] By the electric fields, the liquid crystal molecules on the
right and left sides of the pixel turn in the opposite directions.
The liquid crystal molecules optically compensate with one another,
so that a wide view angle characteristic without tone inversion and
coloring can be obtained. In the embodiment, .theta. is set to
15.degree..
[0044] The source pixel electrode 9 made by the second metal layer
which is the same as the data line 1 extends along the data line 1
and is connected to the storage capacitance electrode 8 made by the
second metal layer formed on the scan lines 2 which are neighboring
each other and serving as sides of the sub pixel.
[0045] The storage capacitance electrode 8 made by the second metal
layer formed on the scan line 2 generates capacitance between the
scan line 2 and itself and functions as a storage capacitor.
[0046] The storage capacitance electrode 8 is covered also with the
second part 6 of the common electrode, so that storage capacitance
is formed also between the storage capacitance electrode 8 and the
second part 6 of the common electrode. With the configuration,
larger storage capacitance can be formed in small area.
[0047] Preferably, the storage capacitance electrode 8 made by the
second metal layer is wider than the scan line 2 and covers the
scan line 2. In such a manner, the storage capacitance electrode 8
made by the second metal layer has the same potential as that of
the pixel electrode 3, and the function of shielding the electric
field from the scan line 2. Consequently, the second part 6 of the
common electrode shielding the scan line 2 does not have to be so
wide.
[0048] In the case where there is no storage capacitance electrode
6 made by the second metal layer, the common electrode 6 for
shielding the electric field of the scan line 2 has to be projected
from the edge of the scan line 2 by 7 .mu.m. By covering the scan
line 2 with the storage capacitance electrode 8 made by the second
metal layer, the width of the projection can be reduced to 6
.mu.m.
[0049] From the above description, it is understood that by
applying the first invention of the application, high aperture
ratio can be obtained in a sub pixel which is long in the scan line
direction.
[0050] By providing the pixel electrode above the source pixel
electrode 9 as illustrated in FIG. 3, the pixel electrode can be
disposed closer to the data line 1 side, and the electric field for
driving the liquid crystal can be generated in a wider area.
[0051] By making the source pixel electrode 9 connected to the
source electrode of the thin film transistor extend along the data
line 1, the source pixel electrode 9 is formed in the short side of
the sub pixel, and the length can be minimized, so that the area of
the part can be also minimized. As a result, the aperture ratio can
be improved.
[0052] By forming the source pixel electrode 9 and the storage
capacitance electrode 8 in a substantially L shape, the aperture
ratio can be increased.
[0053] In the pixel structure, the entire common electrode
potential is generated by the ITO film in the uppermost layer. By
forming the ITO in the uppermost layer in a matrix, it is connected
to the common electrode potential in the periphery. In the sub
pixel, there is no electrode connected to the common electrode
potential in the other layers. Since an electrode which disturbs
improvement in the aperture ratio does not have to be formed, the
aperture ratio can be improved.
[0054] With such a configuration, without forming an extra
electrode which disturbs improvement in the aperture ratio,
sufficiently large storage capacitance can be formed in a small
area, and the electric field from the scan line 2 and the data line
1 can be sufficiently shielded. Consequently, the excellent liquid
crystal display with high aperture ratio and high transmissivity
can be obtained.
[0055] FIG. 4 illustrates an example of forming one pixel by
arranging, along the extension direction of the data line, three
sub pixels shown in FIG. 1. The three sub pixels correspond to the
color layer 20 of R, the color layer 19 of G, and the color layer
21 of B. Like in the case of disposing the sub pixels of R, G, and
B so that they are connected to the same data line, the pixel
structure having sub pixels which are horizontally long has high
aperture ratio. By connecting the sub pixels of R, G, and B to the
same data line, the number of driver ICs for driving the data line
can be decreased, and the liquid crystal display device can be
fabricated at lower cost.
[0056] By disposing the black matrix 34 in the extension direction
of the data line, the part near the data line 1 and opposed to the
TFT is shielded. As a pattern in which the color layers of R, G and
B extend in the extension direction of the scan line 2, at the
border of the color layers, a color-overlap shield part 36 is
disposed so that the color layers of about 6 .mu.m overlap. Since
the part above the scan line 2 is shielded with the storage
capacitance electrode 8 made by the second metal layer and the
third part 6 of the common electrode formed of ITO, the liquid
crystal is not moved by the electric field from the scan line 2.
Consequently, it is unnecessary to increase the light shield
performance so much. By setting the width of the color-overlap
shield part 36 to 6 .mu.m, mixture of colors between the color
layers can be prevented and the light shield part does not extend
to the opening part. Thus, high transmissivity can be
maintained.
Second Embodiment
[0057] A second embodiment of the present invention will be
described with reference to FIGS. 5 and 6. FIG. 5 is a plan view
illustrating the configuration of one sub pixel in a liquid crystal
display device as a second embodiment of the present invention.
FIG. 6 is a cross section taken along line A-A' of HG 5.
[0058] The pixel of the second embodiment illustrated in FIGS. 5
and 6 will be described in detail in fabricating order.
[0059] First, on a glass substrate as the first insulating
substrate 12, the scan line 2 is formed by a first metal layer made
by 2500 A of Cr.
[0060] As the gate insulating film 13, 5000 A of SiNx and a thin
film semiconductor layer made of 2000 A of a-Si and 500 A of n-a-Si
are formed. The thin film semiconductor layer 10 is patterned while
leaving only a TFT part provided as a switching element of the
pixel. By a second metal layer made by 2500 A of Cr, the data line
1, source/drain electrodes of the TFT, the source pixel electrode 9
connected to the source electrode of the TFT, and the storage
capacitance electrode 8 are formed.
[0061] Using the source/drain electrodes of the TFT as a mask,
n-a-Si in the TFT channel part is removed.
[0062] Subsequently, a pixel electrode 41 having a plane shape is
formed by 800 A of a transparent electrode made of ITO.
[0063] As the protection insulating film 14, 6000 A of SiNx is
formed. The through hole 25 connecting the pixel electrode is
formed.
[0064] On the protection insulating film 14, a pattern is formed by
a transparent electrode made by 800 A of ITO, which is made of the
first part 5 of the common electrode, the second part 6 of the
common electrode shielding the scan line, and the third part 7 of
the common electrode shielding the data line.
[0065] A TFT array is formed according to the above-described
method.
[0066] Subsequently, a method of manufacturing a color filter
substrate will be described. On the back face of the second
transparent insulating substrate 22, 200 A of the ITO film 23 is
formed. The black matrix 34 is formed on the surface and, after
that, a pattern is formed in order of the green (G) layer 19, the
red (R) layer 20, and the blue (B) layer 21. Further, the overcoat
layer 18 is formed and, on the overcoat layer 18, the pillar spacer
35 is formed.
[0067] The alignment films 15 and 16 are formed on the surface of
the array substrate and the surface of the color filter substrate
fabricated as described above, and rubbing process is performed in
the direction of 32. The substrates are adhered to each other, a
liquid crystal material is injected in the space between the
substrates, and the resultant is sealed. The liquid crystals 17 are
aligned in the direction of the initial alignment 32 of the liquid
crystals.
[0068] Further, on the outer sides of the glass substrates on both
sides, the polarizers 11 and 24 are adhered. The direction of the
absorption axis of the incident-side polarizer on the TFT array
substrate side is matched with the direction of the initial
alignment 32 of the liquid crystals.
[0069] By providing the liquid crystal display panel fabricated as
described above with a backlight and a drive circuit, an
active-matrix liquid crystal display device of the transverse
electric field type of the second embodiment is completed.
[0070] The first part 5 of the common electrode and the second part
6 of the common electrode shielding the scan line are formed
substantially in parallel to each other and are bent in a center
part of the pixel. Since the scan lines 2 and the common electrodes
5 constructing the comb-shaped electrode extending in the extension
direction of the scan line are bent symmetrically with respect to
the liquid crystal alignment direction, across the pixel electrode
41 and the common electrodes 5, a fringe electric field in the
direction turned from the perpendicular direction (the extension
direction of the data line) only by .theta. in the clockwise
direction is applied on the right half side in the diagram of the
pixel, and the electric field in the direction turned from the
perpendicular direction only by .theta. in the counterclockwise
direction is applied on the left half side in the diagram of the
pixel.
[0071] By the electric fields, the liquid crystal molecules on the
right and left sides of the pixel turn in the opposite directions.
The liquid crystal molecules optically compensate with one another,
so that a wide view angle characteristic without tone inversion and
coloring can be obtained. In the embodiment, .theta. is set to
8.degree..
[0072] The source pixel electrode 9 made by the second metal layer
which is the same as the data line 1 extends along the data line 1
and is connected to the storage capacitance electrode 8 made by the
second metal layer formed on the scan lines 2 which are neighboring
each other and serving as sides of the sub pixel.
[0073] By making the source pixel electrode 9 connected to the
source electrode of the thin film transistor extend along the data
line 1, the source pixel electrode 9 is formed in the short side of
the sub pixel, and the length can be reduced the most, so that the
area of the part can be minimized. It can improve the aperture
ratio.
[0074] The storage capacitance electrode 8 made by the second metal
layer formed on the scan line 2 generates capacitance between the
scan line 2 and itself and functions as a storage capacitor.
[0075] The storage capacitance electrode 8 is covered also with the
second part 6 of the common electrode, so that storage capacitance
is formed also between the storage capacitance electrode 8 and the
third part 6 of the common electrode. With the configuration,
larger storage capacitance can be formed in small area.
[0076] Preferably, the storage capacitance electrode 8 made by the
second metal layer is wider than the scan line 2 and covers the
scan line 2. In such a manner, the storage capacitance electrode 8
made by the second metal layer has the same potential as that of
the pixel electrode 41, and the function of shielding the electric
field from the scan line 2. Consequently, the second part 6 of the
common electrode shielding the scan line 2 does not have to be so
wide.
[0077] In the case where there is no storage capacitance electrode
8 made by the second metal layer, the common electrode 6 for
shielding the electric field of the scan line 2 has to be projected
from the edge of the scan line 2 by 7 .mu.m. By covering the scan
line 2 with the storage capacitance electrode 8 made by the second
metal layer, the width of the projection can be reduced to 6
.mu.m.
[0078] The third part 7 of the common electrode which shields the
data line 1 is formed so as to shield the region between the data
line 1 and the source pixel electrode 9 made by the second metal
layer. Consequently, the liquid crystal is deformed by the electric
field applied across the data line 1 and the pixel electrode 41,
and a cross talk can be suppressed by light leakage from the
deformed part.
[0079] The pillar spacer 35 is disposed in a position which is on
the black matrix of the sub pixel of B and is in contact with a
part near the source pixel electrode 9 on the array substrate. In
such a manner, high aperture ratio can be maintained without
exerting influence on the aperture.
[0080] As described above, by applying the second invention of the
present application, high aperture ratio can be obtained in a sub
pixel which is long in the scan line direction.
[0081] In the pixel structure, the entire common electrode
potential is generated by the ITO film in the uppermost layer. By
forming the ITO in the uppermost layer in a matrix, it is connected
to the common electrode potential in the periphery. In the sub
pixel, there is no electrode connected to the common electrode
potential in the other layers. Since an electrode which disturbs
improvement in the aperture ratio does not have to be formed, the
aperture ratio can be improved.
[0082] With such a configuration, without forming an extra
electrode which disturbs improvement in the aperture ratio,
sufficiently large storage capacitance can be formed in a small
area, and the electric field from the scan line 2 and the data line
1 can be sufficiently shielded. Consequently, the excellent liquid
crystal display with high aperture ratio and high transmissivity
can be obtained.
Third Embodiment
[0083] A third embodiment of the present invention will be
described with reference to FIGS. 7, 8, and 9. FIG. 7 is a plan
view illustrating the configuration of one sub pixel in a liquid
crystal display device as a third embodiment of the present
invention. FIG. 8 is a cross section of a TFT substrate, taken
along line A-A' in FIG. 7.
[0084] The pixel of the second embodiment illustrated in FIGS. 7 to
9 will be described in detail in fabricating order.
[0085] First, on a glass substrate as the first insulating
substrate 12, the scan line 2 is formed by a first metal layer made
by 2500 A of Cr.
[0086] As the gate insulating film 13, 5000 A of SiNx and a thin
film semiconductor layer made of 2000 A of a-Si and 500 A of n-a-Si
are formed. The thin film semiconductor layer 10 is patterned while
leaving only a TFT part provided as a switching element of the
pixel. By a second metal layer made by 2500 A of Cr, the data line
1, source/drain electrodes of the TFT, the source pixel electrode 9
connected to the source electrode of the TFT, and the storage
capacitance electrode 8 are formed.
[0087] Using the source/drain electrodes of the TFT as a mask,
n-a-Si in the TFT channel part is removed.
[0088] As the protection insulating film 14, 6000 A of SiNx is
formed.
[0089] On the protection insulating film 14, a plane-shaped common
electrode 43 is formed by a transparent electrode made of 800 A of
ITO. In the plane-shaped common electrode 43, a through hole 44 for
connecting a pixel electrode is formed.
[0090] As a second protection insulating film 45, 3000 A of SiNx is
formed.
[0091] The through hole 25 is formed in the gate insulating film
13, the protection insulating film 14, and the second protection
insulating film 45.
[0092] Further, on the resultant, a pattern made of a plurality of
stripe-shaped pixel electrodes 42 and the second part 46 of the
pixel electrode coupling the pixel electrodes 42 is formed by a
transparent electrode made of 800 A of ITO. The pattern is
connected to the source pixel electrode 9 via the through holes 25
and 44 in the second part 46 of the pixel electrode.
[0093] A TFT array is formed according to above-described
method.
[0094] A method of manufacturing a color filter substrate will be
described (refer to FIG. 4). On the back face of the second
transparent insulating substrate 22, 200 A of the ITO film 23 is
formed. The black matrix 34 is formed on the surface and, after
that, a pattern is formed in order of the green (G) layer 19, the
red (R) layer 20, and the blue (B) layer 21. Further, the overcoat
layer 18 is formed and, on the overcoat layer 18, the pillar spacer
35 is formed.
[0095] The alignment films 15 and 16 are formed on the surface of
the array substrate and the surface of the color filter substrate
fabricated as described above, and rubbing process is performed in
the direction of 32. The substrates are adhered to each other, a
liquid crystal material is injected in the space between the
substrates, and the resultant is sealed. The liquid crystals 17 are
aligned in the direction of the initial alignment 32 of the liquid
crystals.
[0096] Further, the polarizers 11 and 24 are adhered on the outer
sides of the glass substrates on both sides so that polarization
axes are orthogonal to each other. The direction of the absorption
axis of the incident-side polarizer on the TFT array substrate side
is matched with the direction of the initial alignment 32 of the
liquid crystals.
[0097] By providing the liquid crystal display panel fabricated as
described above with a backlight and a drive circuit, an
active-matrix liquid crystal display device of the transverse
electric field type of the third embodiment is completed.
[0098] Since the scan lines 2 and the stripe-shaped pixel
electrodes 42 extending in the extension direction of the scan
lines 2 are bent symmetrically with respect to the liquid crystal
alignment direction, across the stripe-shaped pixel electrodes 42
and the plane-shaped common electrode 43, a fringe electric field
in the direction turned from the perpendicular direction (the
extension direction of the data line) only by .theta. in the
clockwise direction is applied on the right half side in the
diagram of the pixel, and the electric field in the direction
turned from the perpendicular direction only by .theta. in the
counterclockwise direction is applied on the left half side in the
diagram of the pixel.
[0099] By the electric fields, the liquid crystal molecules on the
right and left sides of the pixel turn in the opposite directions.
The liquid crystal molecules optically compensate with one another,
so that a wide view angle characteristic without tone inversion and
coloring can be obtained. In the embodiment, .theta. is set to
8.degree..
[0100] The source pixel electrode 9 made by the second metal layer
which is the same as the data line 1 extends along the data line 1
and is connected to the storage capacitance electrode 8 made by the
second metal layer formed on the scan lines 2 which are neighboring
each other and serving as sides of the sub pixel.
[0101] By making the source pixel electrode 9 connected to the
source electrode of the thin film transistor extend along the data
line 1, the source pixel electrode 9 is formed in the short side of
the sub pixel, and the length can be reduced the most, so that the
area of the part can be minimized. It can improve the aperture
ratio.
[0102] The storage capacitance electrode 8 made by the second metal
layer formed on the scan line 2 generates capacitance between the
scan line 2 and itself and functions as a storage capacitor.
[0103] The storage capacitance electrode 8 is covered also with the
common electrode 43, so that storage capacitance is formed also
between the storage capacitance electrode 8 and the common
electrode 43. With the configuration, larger storage capacitance
can be formed in small area.
[0104] Preferably, the storage capacitance electrode 8 made by the
second metal layer is wider than the scan line 2 and covers the
scan line 2. In such a manner, the storage capacitance electrode 8
made by the second metal layer has the same potential as that of
the pixel electrode 41, and the function of shielding the electric
field from the scan line 2.
[0105] As described above, by applying the third invention of the
present application, high aperture ratio can be obtained in a sub
pixel which is long in the scan line direction.
[0106] In the pixel structure, the common electrode potential is
generated by the ITO layer as a component of the plane-shaped
common electrode 43. By forming the common electrode in a matrix,
it is connected to the common electrode potential in the periphery.
In the sub pixel, there is no electrode connected to the common
electrode potential in the other layers. Since an electrode which
disturbs improvement in the aperture ratio does not have to be
formed, the aperture ratio can be improved.
[0107] With such a configuration, without forming an extra
electrode which disturbs improvement in the aperture ratio,
sufficiently large storage capacitance can be formed in a small
area.
[0108] The present invention can be used for an active-matrix
liquid crystal display device of a transverse electric field type
and arbitrary equipment using the liquid crystal display device as
a display device.
* * * * *