U.S. patent application number 12/458584 was filed with the patent office on 2010-01-21 for liquid crystal display device.
This patent application is currently assigned to Hitachi Displays, Ltd.. Invention is credited to Hitoshi Komeno, Toshiyuki Koshita.
Application Number | 20100014042 12/458584 |
Document ID | / |
Family ID | 39497554 |
Filed Date | 2010-01-21 |
United States Patent
Application |
20100014042 |
Kind Code |
A1 |
Komeno; Hitoshi ; et
al. |
January 21, 2010 |
Liquid crystal display device
Abstract
The present invention provides a liquid crystal display device
with a narrow picture frame which reduces a sealing defect by
suppressing spreading of an orientation film. In a region inside a
sealing material and outside a display region, an uneven surface
for suppressing spreading of the orientation film is formed. It is
preferable that the uneven surface is formed using an insulation
film and, at the same time, an etching stopper layer is formed
below the insulation film which forms the uneven surface. It is
more preferable that the uneven surface and the stopper layer are
simultaneously formed with a layer used for forming pixels in a
step for forming such a layer thus preventing the increase of
manufacturing steps.
Inventors: |
Komeno; Hitoshi; (Mobara,
JP) ; Koshita; Toshiyuki; (Chosei, JP) |
Correspondence
Address: |
Stanley P. Fisher;Reed Smith LLP
Suite 1400, 3110 Fairview Park Drive
Falls Church
VA
22042-4503
US
|
Assignee: |
Hitachi Displays, Ltd.
|
Family ID: |
39497554 |
Appl. No.: |
12/458584 |
Filed: |
July 16, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
11984376 |
Nov 16, 2007 |
7580104 |
|
|
12458584 |
|
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Current U.S.
Class: |
349/153 |
Current CPC
Class: |
G02F 1/1341 20130101;
G02F 1/1337 20130101; G02F 1/13415 20210101; G02F 1/1339
20130101 |
Class at
Publication: |
349/153 |
International
Class: |
G02F 1/1339 20060101
G02F001/1339 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 6, 2006 |
JP |
2006-328939 |
Claims
1. A liquid crystal display device comprising: a plurality of
projection formed between orientation film and sealing material;
wherein height of the projection is lower than that of the
orientation film and that of the sealing material.
2. A liquid crystal display according to claim 1, height of the
sealing material is higher than that of the orientation film.
3. The liquid crystal display device according to claim 2, wherein
the projection is formed on a transparent conductive film.
4. The liquid crystal display device according to claim 3, wherein
the transparent conductive film is ITO.
5. The liquid crystal display device according to claim 3, wherein
another transparent conductive film is formed on the
projection.
6. The liquid crystal display device according to claim 5, wherein
the orientation film and the sealing material is overlapped on the
another transparent conductive film.
7. The liquid crystal display device according to claim 6, wherein
the another transparent conductive film is ITO.
8. A liquid crystal display device comprising: a plurality of
projection formed between orientation film and sealing material;
wherein a part of the orientation film is overlapped with a part of
the plurality of projection, and a part of sealing material is
overlapped with a part of the plurality of projection.
9. The liquid crystal display device according to claim 8, wherein
the sealing material and the orientation film is spaced in plane
view.
10. The liquid crystal display device according to claim 9, wherein
a part of the plurality of projection is arranged at the space in
plane view.
11. The liquid crystal display device according to claim 10,
wherein the plurality of projection is arranged in line shape.
12. The liquid crystal display device according to claim 11,
wherein the plurality of projection in line shape is arranged
alternatively in plane view.
13. The liquid crystal display device according to claim 10,
wherein the plurality of projection is arranged in circle
shape.
14. The liquid crystal display device according to claim 13,
wherein the plurality of projection in circle shape is arranged
alternatively in plane view.
15. The liquid crystal display device according to claim 14,
wherein density of the plurality of projection in circle shape
arranged between the sealing material and the orientation film is
higher than a plurality of space arranged in display region in
plane view.
16. The liquid crystal display device according to claim 10,
wherein the projection is formed on a transparent conductive
film.
17. The liquid crystal display device according to claim 11,
wherein the projection is formed on a transparent conductive
film.
18. The liquid crystal display device according to claim 12,
wherein the projection is formed on a transparent conductive
film.
19. The liquid crystal display device according to claim 13,
wherein the projection is formed on a transparent conductive
film.
20. The liquid crystal display device according to claim 14,
wherein the projection is formed on a transparent conductive film.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a Continuation Application of U.S.
application Ser. No. 11/984,376 filed on Nov. 16, 2007. The present
application claims priority from U.S. application Ser. No.
11/984,376 filed on Nov. 16, 2007, which claims priority from
Japanese application 2006-328939 filed on Dec. 6, 2006, the content
of which is hereby incorporated by reference into this
application.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a liquid crystal display
device, and more particularly to a technique which is effectively
applicable to a liquid crystal display device with a narrow picture
frame region.
[0004] 2. Description of the Related Art
[0005] A liquid crystal display device has been used as display
devices of various sizes used in applications ranging from a
miniaturized mobile phone to a large-sized television receiver
set.
[0006] FIG. 16 is a plan view for explaining a conventional liquid
crystal display device. Here, a miniaturized liquid crystal display
device is illustrated as one example. In the liquid crystal display
device, a substrate SUB1 and a counter substrate SUB2 are adhered
to each other using a sealing material SL, and liquid crystal is
sandwiched between the substrate SUB1 and the counter substrate
SUB2. An end portion of a side of the counter substrate SUB2 on a
lower side of the drawing retracts from an end portion of a side of
the substrate SUB1 on the lower side of the drawing, and a drive
circuit DRV is mounted on the substrate SUB1 exposed by such
retraction of the end portion. On a surface of the substrate SUB1
which is brought into contact with the liquid crystal, an
orientation film ORI1 is formed by coating in a state that at least
a display region AR is covered with the orientation film ORI1. In
the same manner, on a surface of a counter substrate SUB2 which is
brought into contact with the liquid crystal, an orientation film
ORI2 not shown in the drawing is formed by coating in a state that
at least the display region AR is covered with the orientation film
ORI2.
[0007] Here, as a method for sealing liquid crystal, as shown in
FIG. 16, there has been known a method in which a liquid crystal
filling port is formed in a portion of the sealing material SL, the
liquid crystal is filled in a space defined by the substrate SUB1,
the counter substrate SUB2 and the sealing material SL through the
liquid crystal filling port, and the liquid crystal filling port is
sealed with a sealing material. As a method other than the
above-mentioned method, there has been known a liquid crystal
dropping sealing method in which, as described in patent document 1
(JP-A-11-38424) and patent document 2 (JP-A-2001-51282), for
example, a sealing material SL is formed in an approximately closed
rectangular shape without forming a liquid crystal filling port in
the sealing material SL and, after dropping liquid crystal, a
substrate SUB1 and a counter substrate SUB2 are adhered to each
other to seal the liquid crystal. In this liquid crystal dropping
sealing method, at the time of adhering the substrate SUB1 and the
counter substrate SUB2, the liquid crystal spreads toward the
sealing material SL and hence, in patent document 1 and patent
document 2, for example, there is described a technique which forms
a wall member in a region outside a display region AR and inside
the surrounding sealing material SL thus suppressing spreading of
the dropped liquid crystal.
[0008] Further, with respect to the sealing material SL, for
example, patent document 3 (JP-A-2001-330837) describes a technique
which forms an uneven surface on a portion which overlaps a sealing
material SL for suppressing spreading of the sealing material SL
when a substrate SUB1 and a counter substrate SUB2 are adhered to
each other.
SUMMARY OF THE INVENTION
[0009] Usually, the sealing material SL is formed after a step for
forming orientation films by coating. However, the adhesiveness
between the sealing material SL and the orientation film ORI1 is
not so high. According, as shown in FIG. 16, it is desirable that
the orientation film ORI1 and the sealing material SL do not
overlap each other.
[0010] However, since the orientation film ORI1 is formed by
coating, there arises a drawback that the orientation film ORI1
spreads to the outside of the display region AR. Here, when a
region from an end portion of the substrate SUB1 to the display
region AR, that is, a width of a region outside the display region
AR (so-called picture frame region) is large, there arises no
problem. However, along with narrowing of the width of the picture
frame region, the orientation film ORI1 spreads and extends to a
region where the sealing material SL is formed thus giving rise to
a drawback that sealing becomes defective.
[0011] Such a drawback becomes conspicuous in a miniaturized liquid
crystal display device having a narrow picture frame region,
particularly, in a liquid crystal display device in which a
shortest distance from an end portion of the substrate SUB1 to the
display region AR is 2.0 mm or less.
[0012] Here, drawbacks other than the above-mentioned drawbacks
will become apparent from the description of the whole
specification or drawings of the present application.
[0013] According to a liquid crystal display device of the present
invention, an uneven surface which suppresses spreading of an
orientation film is formed in a region inside a surrounding sealing
material and outside a display region. Here, it is preferable that
the uneven surface is constituted of an insulation film and, at the
same time, an etching stopper layer is formed below the insulation
film which forms the uneven surface. It is further preferable to
form the uneven surface and the stopper layer simultaneously with a
layer used for forming pixels in a step for forming such a layer.
In this case, the increase of manufacturing steps can be
prevented.
[0014] The present invention may be configured as follows, for
example.
[0015] (1) The present invention is directed to a liquid crystal
display device including a first substrate, a second substrate
which is arranged to face the first substrate in an opposed manner,
a sealing material which adheres the first substrate and the second
substrate to each other, and liquid crystal which is sandwiched
between the first substrate and the second substrate, wherein the
first substrate includes pixel electrodes which are formed inside a
display region, an orientation film which is formed at a position
where the orientation film is brought into contact with the liquid
crystal, a plurality of projections which is formed of a first
insulation film below the orientation film in a region inside the
sealing material and outside the display region, a second
insulation film which is arranged at a position where the second
insulation film overlaps the plurality of projections and below the
first insulation film, and is formed of a material to be etched by
an etching gas which forms the first insulation film into the
plurality of projections, and a first stopper layer which is formed
at a position where the first stopper layer overlaps the plurality
of projections and between the first insulation film and the second
insulation film, the first stopper layer being formed of a material
which possesses etching selection property for the etching gas and
protecting the second insulation film from the etching gas, and
assuming a width of the sealing material as W1 and an overlapping
width of the orientation film and the sealing material as W2, a
relationship W2.ltoreq.W1/2 is established.
[0016] (2) In the constitution (1), it is desirable that a shortest
distance from an end portion of the first substrate to the display
region is 2.0 mm or less.
[0017] (3) In the constitution (1) or (2), it is desirable that the
overlapping width W2 of the orientation film and the sealing
material is set to W2=0.
[0018] (4) In any one of the constitutions (1) to (3), it is
desirable that the first substrate includes lines which are
arranged inside the display region, and lead lines which are
arranged outside the display region and supply signals to the
lines, and the lead lines are arranged below the second insulation
film and overlap the first stopper layer.
[0019] (5) In the constitution (4), it is desirable that the first
stopper layer is formed of a conductive film.
[0020] (6) In any one of the constitutions (1) to (5), it is
desirable that the first substrate reflects a surface unevenness
formed by the plurality of projections, and includes a second
stopper layer which is formed at a position where the second
stopper layer covers the plurality of projections and is formed of
a material having a contact angle with the orientation film larger
than a contact angle of the first insulation film with the
orientation film.
[0021] (7) In the constitution (6), it is desirable that the second
stopper layer is formed of the same material as the pixel
electrodes, and is formed on the same layer as the pixel
electrodes.
[0022] (8) In any one of the constitutions (1) to (7), it is
desirable that the first substrate includes a counter electrode
which is formed of a transparent conductive film inside the display
region, and the liquid crystal is driven by an electric field which
is generated between the pixel electrodes and the counter
electrode.
[0023] (9) In the constitution (8), it is desirable that the first
stopper layer is formed of the same material as the counter
electrode, and is formed on the same layer as the counter
electrode.
[0024] (10) In any one of the constitutions (1) to (7), it is
desirable that the second substrate includes a counter electrode
which is formed of a transparent conductive film inside the display
region, and the liquid crystal is driven by an electric field which
is generated between the pixel electrodes and the counter
electrode.
[0025] (11) In the constitution (10), it is desirable that the
first substrate includes an electrode which is formed of a
transparent conductive film and is arranged below the pixel
electrodes and at a position where the electrode overlaps the pixel
electrodes, and a holding capacitance is formed between the
electrode formed of the transparent conductive film and the pixel
electrodes.
[0026] (12) In the constitution (11), it is desirable that the
first stopper layer is formed of the same material as the electrode
formed of the transparent conductive film and is formed on the same
layer as the electrode formed of the transparent conductive
film.
[0027] (13) In any one of the constitutions (1) to (12), it is
desirable that the first insulation film and the second insulation
film are formed of an inorganic insulation film.
[0028] (14) In any one of the constitutions (1) to (13), it is
desirable that the first insulation film and the second insulation
film are formed of a silicon nitride film.
[0029] (15) In any one of the constitutions (1) to (14), it is
desirable that the first stopper layer is formed of a transparent
conductive film.
[0030] (16) In any one of the constitutions (1) to (15), it is
desirable that the plurality of projections is formed in a state
that the projections surround four sides of the display region.
[0031] Here, the above-mentioned constitutions are exemplified only
as one example, and various modifications can be made without
departing from the technical concept of the present invention when
necessary. Further, examples of the constitutions of the present
invention other than the above-mentioned constitutions will become
apparent from the description of the whole specification or
drawings.
[0032] Typical advantageous effects obtained by the present
invention are as follows.
[0033] According to the present invention, it is possible to
provide a liquid crystal display device having a narrow picture
frame which can reduce a sealing defect by suppressing spreading of
an orientation film.
[0034] Other advantageous effect of the present invention will
become apparent from the whole specification.
BRIEF DESCRIPTION OF THE DRAWINGS
[0035] FIG. 1 is a view for explaining a liquid crystal display
device of an embodiment 1 according to the present invention, and
also is a cross-sectional view taken along a line A-A in FIG.
2;
[0036] FIG. 2 is a plan view for explaining the liquid crystal
display device of the embodiment 1 according to the present
invention;
[0037] FIG. 3 is a plan view for explaining one example of a layout
of wiring of the embodiment 1 according to the present
invention;
[0038] FIG. 4 is a plan view for explaining an equivalent circuit
of a pixel;
[0039] FIG. 5 is a plan view of one example of a pixel for
explaining a liquid crystal display device of an embodiment 2
according to the present invention;
[0040] FIG. 6 is a cross-sectional view taken along a line B-B in
FIG. 5;
[0041] FIG. 7 is a plan view of one example of a pixel for
explaining a liquid crystal display device of an embodiment 3
according to the present invention;
[0042] FIG. 8 is a cross-sectional view taken along a line C-C in
FIG. 7;
[0043] FIG. 9 is a view for explaining a liquid crystal display
device of an embodiment 4 according to the present invention, and
also is a cross-sectional view taken along a line A-A in FIG.
2;
[0044] FIG. 10 is a view for explaining a liquid crystal display
device of an embodiment 5 according to the present invention, and
also is a cross-sectional view taken along a line A-A in FIG.
2;
[0045] FIG. 11 is a plan view for explaining one example of a
liquid crystal display device of an embodiment 6 according to the
present invention;
[0046] FIG. 12 is a plan view for explaining another example of the
liquid crystal display device of the embodiment 6 according to the
present invention;
[0047] FIG. 13 is a plan view for explaining a liquid crystal
display device of an embodiment 7 according to the present
invention;
[0048] FIG. 14 is a cross-sectional view taken along a line D-D in
FIG. 13;
[0049] FIG. 15 is a cross-sectional view for explaining a liquid
crystal display device of an embodiment 8 according to the present
invention; and
[0050] FIG. 16 is a plan view for explaining a conventional liquid
crystal display device.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0051] Embodiments of the present invention are explained in
conjunction with drawings. Here, in all drawings and all
embodiments, identical or similar constitutional elements are given
same symbols, and their explanation is omitted.
Embodiment 1
[0052] FIG. 1 is a view for explaining a liquid crystal display
device of an embodiment 1 according to the present invention, and
also is a cross-sectional view taken along a line A-A in FIG. 2.
FIG. 2 is a plan view for explaining the liquid crystal display
device of the embodiment 1 according to the present invention. FIG.
3 is a plan view for explaining one example of a layout of wiring
of the embodiment 1 according to the present invention. FIG. 4 is a
plan view for explaining an equivalent circuit of a pixel.
[0053] As shown in FIG. 2, the liquid crystal display device of
this embodiment is configured such that liquid crystal LC not shown
in the drawing is sandwiched between a transparent insulating
substrate (first substrate) SUB1 made of glass or the like and a
transparent insulating counter substrate (second substrate) SUB2
made of glass or the like. Here, the substrate SUB1 and the counter
substrate SUB2 are adhered to each other using a sealing material
SL. The liquid crystal LC is filled in a space defined by the
substrate SUB1, the counter substrate SUB2 and the sealing material
SL through a liquid crystal filling port formed in the sealing
material SL. Then, the liquid crystal filling port is sealed with a
sealing material. Here, the present invention is not limited to
such a constitution and may manufacture the liquid crystal display
device using a liquid crystal dropping sealing method which uses a
closed sealing material SL having no liquid crystal filling
port.
[0054] An end portion of a side of the counter substrate SUB2 on a
lower side of FIG. 2 retracts from an end portion of a side of the
substrate SUB1 on the lower side of FIG. 2, and a drive circuit DRV
is mounted on the substrate SUB1 exposed by such retraction of the
end portion. On a surface of the substrate SUB1 which is brought
into contact with the liquid crystal, an orientation film ORI1 is
formed by coating in a state that the orientation film ORI1 covers
at least a display region AR. In the same manner, on a surface of
the counter substrate SUB2 which is brought into contact with the
liquid crystal, an orientation film ORI2 not shown in the drawing
is formed by coating in a state that the orientation film ORI2
covers at least the display region AR.
[0055] As shown in FIG. 3 and FIG. 4, the liquid crystal display
device of this embodiment is an active-matrix-type liquid crystal
display device, wherein a plurality of pixels is arranged in a
matrix array. The substrate SUB1 includes a plurality of scanning
signal lines GL and a plurality of video signal lines DL which
intersect the plurality of scanning signal lines GL. In the
vicinity of the respective intersecting portions, thin film
transistors TFT are formed as switching elements of the pixels.
FIG. 4 shows an equivalent circuit of a pixel region PIX
corresponding to one pixel out of the plurality of pixels arranged
in a matrix array. A gate of the thin film transistor TFT is
connected to one of the scanning signal lines GL to which a
scanning signal is applied. One electrode (drain electrode SD1 not
shown in the drawing) of the thin film transistor TFT is connected
to one of video signal lines DL to which a video signal is applied.
A pixel electrode PX not shown in the drawing is connected to
another electrode (source electrode SD2 not shown in the drawing)
of the thin film transistor TFT, and video signal is applied to
another electrode via the thin film transistor TFT. Here, although
there may be a case in which the electrode which is connected to
the video signal line DL is referred to as the source electrode,
for avoiding the confusion, the explanation is made by unifying the
above-mentioned naming in this specification.
[0056] The pixel electrode PX generates a liquid crystal
capacitance CLC between the pixel electrode PX and the counter
electrode CT not shown in the drawing via the liquid crystal LC.
Here, a display is performed by driving the liquid crystal LC with
an electric field generated between the pixel electrode PX and the
counter electrode CT. Further, the pixel electrode PX generates a
holding capacitance Cst between the pixel electrode PX and an
electrode not shown in the drawing to which a predetermined
potential is applied by way of an insulation film not shown in the
drawing.
[0057] As shown in FIG. 3, the respective scanning signal lines GL
are connected with the drive circuit DRV by way of any one of
scanning-signal-line lead lines GLP1, GLP2 which passes a picture
frame region on a left side or a right side in the drawing.
Further, the respective video signal lines DL are connected to the
drive circuit DRV by way of video-signal-line lead lines DLP. On a
lower side of the substrate SUB1, a terminal portion TM which is
connected with a flexible printed circuit board not shown in the
drawing is formed. A layout of wiring shown in FIG. 3 merely
constitutes one example and can be suitably changed. The
constitution of the drive circuit DRV and the number and positions
of the drive circuits DRV can also be suitably changed when
necessary.
[0058] Next, the structure which suppresses spreading of the
orientation film in this embodiment is explained in conjunction
with FIG. 1 and FIG. 2. As shown in FIG. 1, in a region (picture
frame region) outside the display region AR of the substrate SUB1,
the scanning-signal line lead lines GLP1 are formed. On the
scanning-signal line lead lines GLP1, the scanning-signal line lead
lines GLP2 are formed by way of the insulation film IN1. In this
manner, by forming the scanning-signal line lead lines GLP1, GLP2
into the multi-layered structure by way of the insulation film IN1,
the narrow picture frame can be acquired. The insulation film IN2
is formed on the scanning-signal line lead lines GLP2. A stopper
layer ITO1 is formed on the insulation film IN2. An insulation film
IN3 is formed on the stopper layer ITO1. A stopper layer ITO2 is
formed on the insulation film IN3. On the insulation film IN3 and
the stopper layer ITO2, the orientation film ORI1 is formed by
coating at a position where the orientation film ORI1 is brought
into contact with the liquid crystal LC. Thereafter, the sealing
material SL is formed.
[0059] Here, the insulation film IN3 is, in a region inside the
sealing material SL and outside the display region AR, formed into
a plurality of projections PJ by etching. Due to such projections
PJ, unevenness is formed on a surface of the insulation film IN3
and hence, spreading of the orientation film ORI1 can be
suppressed.
[0060] Here, it is more preferable to form the scanning-signal-line
lead lines GLP1, GLP2, the insulation films IN1, IN2, IN3 and the
stopper layers ITO1, ITO2 simultaneously with a layer used for
forming the pixels in a step for forming such a layer. This is
because such simultaneous formation can prevent the increase of
manufacturing steps. Due to such a constitution, the
scanning-signal-line lead lines GLP1, GLP2, the insulation films
IN1, IN2, IN3 and the stopper layers ITO1, ITO2 can be formed using
the same material as a material used for forming the pixels and can
also be formed on the same layer as the pixels.
[0061] For example, the explanation is made with respect to a case
in which the insulation films IN1, IN2, IN3 are formed of a silicon
nitride film which is used for forming the pixel regions PIX, and
the stopper layers ITO1, ITO2 are formed of a transparent
conductive film such as an ITO film used for forming the pixel
regions PIX. In such a case, the insulation film IN3 can be formed
into the projections PJ by dry etching using a mixed gas of sulfur
hexafluoride gas (SF.sub.6) and oxygen (O.sub.2) as an etching gas,
for example. In this case, since the insulation film IN2 arranged
below the insulation film IN3 is also formed of a material which is
etched using the same etching gas, to prevent such etching of the
insulation film IN2, the stopper layer ITO1 which is formed of a
material having etching selectivity for such an etching gas is
arranged so as to protect the insulation film IN2 from the etching
gas. Accordingly, it is possible to protect the insulation film IN2
and the scanning-signal-line lead lines GLP1, GLP2 and the
insulation film IN1 which are arranged below the insulation film
IN2 from the etching gas used for forming the projections PJ.
Accordingly, the stopper layer ITO1 is formed in a region which
overlaps a region where the projections PJ are formed.
[0062] Here, stopper layer ITO1 is formed of a conductive material
and, at the same time, is formed such that the stopper layer ITO1
overlaps at least portions of the scanning-signal-line lead lines
GLP1, GLP2 thus also acquiring an electrical shielding effect. In
this case, it is desirable to apply a predetermined potential to
the stopper layer ITO1.
[0063] Here, although the explanation is made with respect to the
portions of the scanning-signal-line lead lines GLP1, GLP2 in FIG.
1, portions of the video-signal-line lead lines DLP may also adopt
the substantially equal constitution. Further, it is desirable that
the projections PJ are formed so as to surround four sides of the
display region AR as shown in FIG. 2.
[0064] Next, a role of the stopper layer ITO2 formed at a position
where the stopper layer ITO2 covers the projections PJ is
explained. The stopper layer ITO2 is formed of a material having a
contact angle with the orientation film ORI1 larger than a contact
angle of the insulation film IN3 which constitutes the projections
PJ with the orientation film ORI1. That is, the stopper layer ITO2
is formed of the material (for example, ITO) which exhibits
wettability to the orientation film ORI1 lower than the wettability
of the insulation film IN3 (for example, silicon nitride film). Due
to such a constitution, the stopper layer ITO2 functions as a
stopper for suppressing spreading of the orientation film ORI1 more
effectively. Further, since the stopper layer ITO2 is formed to
reflect the unevenness of the projections PJ, the stopper layer
ITO2 can exhibit a high stopper effect compared to a stopper layer
having a flat surface. It is desirable that the stopper layer ITO2
is formed of the same material as the pixel electrodes PX and is
formed on the same layer as the pixel electrodes PX.
[0065] Further, the stopper layer ITO2 may also play a role of an
etching stopper. For example, in the inside of the pixel region
PIX, in forming a transparent conductive film made of ITO or the
like on the insulation film IN3 as the pixel electrode PX not shown
in the drawing, for example, it is possible to protect the stopper
layer ITO1 from an oxalic acid used for patterning the transparent
conductive film.
[0066] Heretofore, the explanation has been made with respect to
the case in which the silicon nitride film is used for forming the
insulation films IN1, IN2, IN3. However, the present invention is
not limited to such a case, and a silicon oxide film may be adopted
for partially or wholly forming the insulation films IN1, IN2, IN3.
Alternatively, an inorganic insulation film or an organic
insulation film may be adopted for partially or wholly forming
these insulation films IN1, IN2, IN3. The stopper layers ITO1, ITO2
are not always formed of the transparent conductive film, and other
conductive material, an insulation material or a semiconductor
material may be adopted for forming the stopper layers ITO1,
ITO2.
Embodiment 2
[0067] Next, the present invention is explained in conjunction with
a case in which the present invention is applied to an IPS-type
liquid crystal display device. FIG. 5 is a plan view of one example
of the pixel for explaining the liquid crystal display device of an
embodiment 2 according to the present invention. FIG. 6 is a
cross-sectional view taken along a line B-B in FIG. 5.
[0068] As shown in FIG. 5 and FIG. 6, portions of the scanning
signal lines GL which are formed on the substrate SUB1 constitute
the gate electrodes GT of the thin film transistors TFT. Here, the
scanning-signal-line lead lines GLP1 explained in the embodiment 1
are also simultaneously formed. The insulation film IN1 explained
in the embodiment 1 is formed on the scanning-signal-line lead
lines GLP1 and functions as a gate insulation film. Semiconductor
films AS made of amorphous silicon or the like, for example, are
formed on the insulation film IN1. On the semiconductor films AS,
the video signal lines DL, the drain electrodes SD1 and the source
electrodes SD2 which are integrally formed with the video signal
lines DL are formed. Here, the video-signal-line lead lines DLP and
the scanning-signal-line lead lines GLP2 explained in the
embodiment 1 are also simultaneously formed. Here, the
scanning-signal-line lead lines GLP2 are connected with the
scanning signal lines GL via contact holes not shown in the
drawing.
[0069] Then, the insulation film IN2 explained in the embodiment 1
is formed on the video signal lines DL and the like, and the
counter electrode CT is formed on the insulation film IN2. Here,
the stopper layer ITO1 explained in the embodiment 1 can be also
simultaneously formed. The counter electrode CT is formed in a
planar shape, and opening portions CTOP are formed in the counter
electrode CT in the vicinity of the contact holes CH1. At portions
of the counter electrode CT except for the opening portions CTOP,
the counter electrode CT overlaps the scanning signal lines GL and
the video signal lines DL by way of an insulation film thus
functioning also as an electrical shield. On the scanning signal
lines GL and the video signal lines DL, the insulation film IN3
explained in the embodiment 1 is formed. The pixel electrodes PX
are formed on the insulation film IN3. Here, the stopper layer ITO2
explained in the embodiment 1 can be also simultaneously formed.
The pixel electrode PX is formed in a shape having linear portions
(for example, a comb-teeth shape shown in FIG. 5) and overlaps the
counter electrode CT by way of the insulation film IN3. The pixel
electrode PX is connected to the source electrode SD2 via the
contact hole CH1. The liquid crystal LC is driven by an electric
field generated between the pixel electrode PX and the counter
electrode CT. Further, a holding capacitance Cst is generated
between the pixel electrode PX and the counter electrode CT by way
of the insulation film IN3. Further, the orientation film ORI1 is
formed on the pixel electrodes PX.
[0070] Further, on the counter substrate SUB2, a light blocking
film BM, color filters CF, an overcoat film OC and the orientation
film ORI2 are formed. On a surface of the substrate SUB1 opposite
to the liquid crystal, a polarizer POL1 is arranged. On a surface
of the counter substrate SUB2 opposite to the liquid crystal, a
polarizer POL2 is arranged.
[0071] Here, as explained in conjunction with the embodiment 1, the
insulation films IN1, IN2, IN3 may be formed of the silicon nitride
film, for example. However, a film for forming such insulation
films is not limited to the silicon nitride film. Further, in the
same manner as the embodiment 1, the pixel electrodes PX, the
stopper layer ITO1, the counter electrode CT and the stopper layer
ITO2 may be formed of the transparent conductive film such as an
ITO film or the like. However, a film for forming these parts is
not limited to such a transparent conductive film.
Embodiment 3
[0072] Next, the present invention is explained in conjunction with
a case in which the present invention is applied to a liquid
crystal display device of a vertical electrical field type. FIG. 7
is a plan view of one example of the pixel for explaining the
liquid crystal display device of an embodiment 3 according to the
present invention. FIG. 8 is a cross-sectional view taken along a
line C-C in FIG. 7. Here, in the embodiment 3, the explanation is
made only with respect to the constitution which makes this
embodiment differ from the embodiment 2, and the explanation of
parts identical with the parts in the embodiments 1, 2 is
omitted.
[0073] As shown in FIG. 7 and FIG. 8, in the embodiment 3, the
counter electrode CT is formed on the counter-substrate-SUB2 side,
for example, between the orientation film ORI2 and the overcoat
film OC. Further, the pixel electrode PX is formed on the
substantially whole area of the pixel region PIX in a planar shape.
Further, the liquid crystal LC is driven by an electric field
generated between the pixel electrodes PX formed on the substrate
SUB1 and the counter electrode CT formed on the counter substrate
SUB2.
[0074] Further, at portions where the counter electrode CT is
formed in the embodiment 2, a shield electrode SHD is formed using
a transparent conductive film made of ITO or the like, for example,
in the embodiment 3. The shield electrode SHD may be simultaneously
formed with a stopper layer ITO1. The shield electrode SHD is
formed in a planar shape and opening portions SHDOP are formed in
the shield electrode SHD in the vicinity of the contact holes CH1.
At portions of the shield electrode SHD except for the opening
portions SHDOP, the shield electrode SHD overlaps the scanning
signal line GL and the video signal line DL by way of an insulation
film thus functioning as an electric shield. Further, between the
pixel electrodes PX and the shield electrode SHD, a holding
capacitance Cst having a large area, that is, a large capacitance
is formed by way of the insulation film IN3.
Embodiment 4
[0075] Next, a modification of the embodiment 1 is explained. FIG.
9 is a view for explaining the liquid crystal display device of an
embodiment 4 according to the present invention, and also is a
cross-sectional view taken along a line A-A in FIG. 2.
[0076] The constitution which makes this embodiment differ from the
embodiment explained in conjunction with FIG. 1 lies in that the
modification omits the stopper layer ITO2 and constitutions other
than such a constitution are substantially equal to the
corresponding constitution of the embodiment 1.
[0077] When etching selection property is provided between the
films (for example, pixel electrodes PX) formed on the stopper
layer ITO1 and the stopper layer ITO1, it is unnecessary to provide
the stopper layer ITO2 as an etching stopper for protecting the
stopper layer ITO1. For example, also in using amorphous ITO at the
time of forming the stopper layer ITO1, by applying heat treatment
to the stopper layer ITO1 at a temperature of 230.degree. C. before
forming the pixel electrodes PX, it is possible to form the stopper
layer ITO1 into a polycrystalline ITO layer. Accordingly, even when
the stopper layer ITO1 is exposed at the time of etching the pixel
electrodes PX which are formed of amorphous ITO using an oxalic
acid, polycrystalline ITO is not etched by the oxalic acid and
hence, the stopper layer ITO2 can be omitted.
[0078] Also in this case, the projection PJ can suppress spreading
of the orientation film ORI1.
Embodiment 5
[0079] Next, another modification of the embodiment 1 is explained.
FIG. 10 is a view for explaining the liquid crystal display device
of an embodiment 5 according to the present invention, and also is
a cross-sectional view taken along a line A-A in FIG. 2.
[0080] The constitution which makes this embodiment differ from the
embodiment explained in conjunction with FIG. 1 lies in that the
scanning-signal-line lead lines GLP2 are omitted and constitutions
other than such a constitution are substantially equal to the
corresponding constitution of the embodiment 1.
Embodiment 6
[0081] Next, in the embodiment 6, a planar shape of the projections
PJ which is applicable to the embodiments 1 to 5 is explained.
[0082] FIG. 11 is a plan view for explaining one example of the
liquid crystal display device of an embodiment 6 according to the
present invention. In FIG. 11, the projections PJ are respectively
formed in a continuously linear shape.
[0083] FIG. 12 is a plan view for explaining another example of the
liquid crystal display device of the embodiment 6 according to the
present invention. In FIG. 12, the projections PJ are respectively
formed in an interrupted linear shape. Further, in a row
constituted of a plurality of projections PJ, by forming cut
portions in a staggered manner, spreading of the orientation film
ORI1 can be suppressed.
[0084] Here, the planar shape of the projections PJ according to
the present invention is not limited to examples shown in FIG. 11
and FIG. 12, and the projection PJ may be formed in other
shapes.
Embodiment 7
[0085] Next, the explanation is made with respect to the structure
which suppresses spreading of the orientation film ORI2 on the
counter-substrate-SUB2 side. FIG. 13 is a plan view for explaining
the liquid crystal display device of an embodiment 7 according to
the present invention. FIG. 14 is a cross-sectional view taken
along a line D-D in FIG. 13.
[0086] On the counter-substrate-SUB2 side, by forming parts
(columnar spacers SPC in FIG. 13) substantially equal to or similar
to columnar spacers SPC formed in the display region AR in a region
inside the sealing material SL and outside the display region AR,
it is possible to suppress spreading of the orientation film ORI2.
In this case, it is desirable to form such columnar spacers SPC
with density higher than density of the columnar spacers SPC in the
display region AR. For example, the columnar spacers SPC are formed
in the display region AR with the density of 5 to 150 pieces of
columnar spacers SPC per 1 mm.sup.2, while the columnar spacers SPC
are formed in the picture frame region with the density of 200 or
more pieces of columnar spacers SPC per 1 mm.sup.2.
[0087] Further, with respect to the columnar spacers SPC in the
picture frame region, it is desirable to arrange the columnar
spacers SPC in a plurality of rows as well as in a staggered manner
as shown in FIG. 13 for suppressing spreading of the orientation
film ORI2. Here, the columnar spacers SPC in the picture frame
region may be formed in a shape which differs from a shape of the
columnar spacers SPC in the display region AR. For example, the
columnar spacers SPC in the picture frame region may be formed in a
continuously linear shape, an interrupted linear shape or other
shape, for example.
Embodiment 8
[0088] Next, the explanation is made with respect to a case in
which the sealing material SL and the orientation film ORI1 overlap
each other. FIG. 15 is a cross-sectional view for explaining the
liquid crystal display device of an embodiment 8 according to the
present invention. As in the case of the respective embodiments
explained heretofore, it is desirable that the orientation film
ORI1 does not overlap the sealing material SL. However, as shown in
FIG. 15, assuming a width of the sealing material SL as W1 and a
width at which the orientation film ORI1 and the sealing material
SL overlap each other as W2, provided that a relationship of
W2.ltoreq.W1/2 is satisfied, an adhesion strength of the sealing
material SL can be ensured to some extent and hence, the
overlapping is allowable within a range that such a condition is
satisfied. Here, although the explanation has been made with
respect to the orientation film ORI1, the same goes for the
orientation film OR2.
[0089] Although the present invention has been explained in
conjunction with the embodiments heretofore, the constitutions
explained in the respective embodiments heretofore constitute
merely one example, and various modifications can be properly made
without departing from the technical concept of the present
invention. For example, when the thin film transistor TFT is formed
using polycrystalline silicon, the thin film transistor TFT may
adopt the top gate structure, or a background film may be formed
between the substrate and the semiconductor film. For example, when
the present invention is applied to a reflective or transflective
liquid crystal display device, a portion of the film may be
replaced with a reflection film or a reflection film may be
additionally provided. Besides the above-mentioned constitutions,
various modifications are conceivable. Further, the constitutions
explained in conjunction with the respective embodiments may be
used in combination provided that these embodiments do not
contradict each other.
* * * * *