JPH1130788A - Liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a leakage current between an upper and lower substrates, without increase in the driving voltage or deterioration of the image display performance, by forming an insulation film selectively in the prescribed area only of the counter electrode. SOLUTION: On the oppositely facing substrate 110, a color filter is formed consisting of a color part 109 and a black matrix 115; on the color filter, successively, the counter electrode 116 comprising ITO is formed, as are an insulation film 117 for preventing leakage between the electrodes provided on the upper and lower substrates, and an oriented film 118. In this case, the counter electrode 116 and the oriented film 118 are provided on the entire surface, but the insulation film 117 are only on the part oppositely facing the source electrode 105 and the drain electrode 106 on a TFT array substrate 101. Thus, by providing the insulation film 17 selectively in the area other than the pixel opening part, problems can be avoided such as increase in the driving voltage or deterioration of the display characteristic, and also a leakage current between the substrates can be effectively prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a liquid crystal display device, and more particularly, to a liquid crystal display device having a narrow cell gap.

[0002]

2. Description of the Related Art A smectic liquid crystal material having a large spontaneous polarization, such as a ferroelectric liquid crystal and an antiferroelectric liquid crystal, has characteristics of exhibiting high-speed response and a wide viewing angle in a surface stabilized display mode. Therefore, it is expected as a material for a next-generation liquid crystal display device. Particularly in recent years, many attempts have been made to display moving images in combination with an active matrix.

However, a liquid crystal material having such a large spontaneous polarization has a dielectric constant of several tens to several thousands, which is very large as compared with a nematic material, so that a conventional nematic liquid crystal material is used. It has been found that the thickness of the alignment film, which has almost no effect on the liquid crystal display element, greatly affects the display performance. That is, when an electric field is applied between the pixel electrode and the counter electrode, the electric field is applied not only to the liquid crystal layer itself, but also to the alignment film and the insulating film constituting the liquid crystal cell.
The voltage is divided by all the peripheral members electrically arranged in series between the pixel electrode and the counter electrode.

In the case of a nematic liquid crystal material, an organic polymer material often used for an alignment film and an oxide / inorganic material constituting an insulating film have a dielectric constant of almost the same order as that of the liquid crystal material, but the thickness of the liquid crystal layer is small. Is about 50 times as large as the total thickness of the alignment film and the insulating film, it can be said that there is almost no influence. However, in the case of a smectic material having a large dielectric constant, a partial pressure on a peripheral member such as an alignment film cannot be ignored.

On the other hand, when a liquid crystal material having such a large spontaneous polarization is used for a liquid crystal display device, the surface stability (S
(urface Stabilized) state. This is to forcibly unwind the helical structure derived from the material by reducing the cell gap. In this case, the cell gap is often set to about 2 μm in consideration of the display performance in the birefringence mode. For this reason, a general TFT-TN cell (cell gap 5 μm)
(around m), there was no problem at all. Leakage current occurred between the cell upper and lower substrates due to the protrusion of the color filter, dust in the cell assembling process, and loss of array wiring by spacers, etc. Resulting in.

In order to prevent the leakage current between the upper and lower substrates, an insulating film made of an inorganic material is generally provided on the entire surface of the counter electrode on the color filter side. FIG. 4 shows a cross section of the structure of such a conventional liquid crystal cell.

In the conventional liquid crystal cell shown in FIG. 4, a semiconductor film 304 is formed on a substrate 301 made of glass or plastic via a gate electrode 302 and a gate insulating film 303.
Is formed, and the source electrode 30 is formed on the semiconductor film 304.
5 and a drain electrode 306 are formed.
The FT is configured. The drain electrode 30 of this TFT
6 is ITO (Indium Tin Oxide)
Is connected. Further, an alignment film 308 is formed on the TFT and the pixel electrode 307.
Are formed.

A color filter composed of a color portion 309 and a black matrix 315 is formed on the opposing substrate 310, and a color filter 31 made of ITO is formed thereon in that order.
6. An insulating film 317 and an alignment film 318 made of an inorganic material for preventing leakage between electrodes provided on the upper and lower substrates are formed on the entire surface.

The above-described TFT array substrate 301 and color filter substrate 310 are arranged to face each other with a spacer 312 interposed therebetween, and a liquid crystal layer 311 having a large spontaneous polarization is sandwiched between them. Polarizers 313 and 314 are arranged in a crossed Nicols state on the surfaces of the TFT substrate 301 and the color filter substrate 310 opposite to the opposing surfaces.

In the liquid crystal cell configured as described above, the insulating film 317 is formed on the entire surface of the color filter substrate 310.
Is provided. The insulating film 317 is effective in preventing short circuit between the two substrates, but since the pixel potential applied to the pixel electrode is also divided into the insulating film 317, an effective voltage is applied to the liquid crystal layer 311. Cannot be applied, resulting in a problem that the driving voltage is increased.

In recent years, a liquid crystal display device utilizing selective reflection of cholesteric liquid crystal also tends to set a narrow cell gap in order to reduce the driving voltage. In this liquid crystal display device having memory characteristics, since it is not necessary to apply an electric field during the display image holding period, although the drive voltage is expected to be reduced,
A rewriting voltage requires a higher voltage than a general TFT-TN panel. In order to efficiently apply the rewriting voltage, it is not preferable to provide an insulating film on the entire surface of the counter electrode.

As a method for solving this problem, a method has been proposed in which a counter electrode facing the first signal line is patterned (Japanese Patent Application No. 7-92489). FIG. 5 shows a cross section of a liquid crystal cell having this structure. In this liquid crystal cell,
The source electrode 305 and the drain electrode 30 having a convex structure
By patterning the opposing electrode 316 facing 6, a short circuit between both substrates is prevented.

In addition, in the liquid crystal cell shown in FIG. 5, in addition to this, the portion of the counter electrode 316 facing a signal line (not shown) having a convex structure is often patterned. The counter electrode facing the signal line can be patterned by removing ITO by a technique such as etching using a resist. However, such a counter electrode has a high resistance value, and often causes problems on image display such as crosstalk.

[0014]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and has been made in view of the above-mentioned problem. It is an object of the present invention to provide a liquid crystal display device in which a leak current is prevented.

[0015]

Means for Solving the Problems In order to solve the above problems, the present inventors have made intensive studies and as a result, have selectively insulated only a predetermined region of the counter electrode, not the entire surface of the counter electrode. It has been found that by forming a film, even if the cell gap is narrow, it is possible to prevent a leak current between the upper and lower substrates without increasing the driving voltage or lowering the image display performance. The present invention is based on such findings.

That is, according to the present invention (claim 1), a plurality of scanning lines, a plurality of signal lines, a plurality of switching elements formed near intersections of the scanning lines and the signal lines, and the switching elements are connected to the switching elements. A first substrate having a pixel electrode, a counter electrode, and an insulating film formed on the counter electrode; a second substrate disposed opposite to the first substrate; A liquid crystal layer sandwiched between a first substrate and a second substrate, wherein the insulating film is selectively formed in a region on the counter electrode not facing the pixel electrode. Provide equipment.

Further, according to the present invention (claim 2), a plurality of scanning lines, a plurality of signal lines, a plurality of switching elements formed near intersections of the scanning lines and the signal lines, and a plurality of switching elements connected to the switching elements. A first substrate having a pixel electrode, a counter electrode, and an insulating film formed on the counter electrode; a second substrate disposed opposite to the first substrate; A liquid crystal layer sandwiched between a first substrate and a second substrate, wherein the insulating film is selectively formed in a region on the counter electrode facing the switching element. Provide equipment.

Further, according to the present invention (claim 3), a plurality of scanning lines, a plurality of signal lines, a plurality of switching elements formed near the intersection of the scanning lines and the signal lines, and the switching elements are connected. A first substrate having a pixel electrode, a counter electrode, and an insulating film formed on the counter electrode; a second substrate disposed opposite to the first substrate; A liquid crystal layer sandwiched between first and second substrates, wherein the insulating film is selectively formed in a region on the counter electrode facing the signal line or the scanning line. To provide a liquid crystal display device.

In the liquid crystal display device of the present invention, the region on the counter electrode where the insulating film is formed is a region facing the convex portion on the first substrate, that is, the array substrate. This area is
This corresponds to a region other than the opening of the color filter. More specifically, this region is a region on the counter electrode facing the switching element and the signal line or in the vicinity thereof, or is a region on the counter electrode facing the switching element or in the vicinity thereof.

The insulating film may be an inorganic insulating film such as SiO ₂ or SiN or an organic insulating film such as a resist. The film thickness is not particularly limited, but is generally preferably 0.05 to 0.5 μm.

The method for selectively forming the insulating film is not particularly limited, and various methods can be used. For example, after the film is formed by sputtering or CVD, it can be selectively formed by patterning by photolithography. Alternatively, it can be selectively formed by a mask sputtering method in which sputtering is performed using a predetermined mask.

According to the present invention, the thickness is preferably 4.5 μm or less, and
The present invention is particularly suitably applicable to a liquid crystal display device having a narrow cell gap of μm or less. The liquid crystal material is not particularly limited, but among liquid crystal display devices that require a narrow cell gap, an effect is obtained when a smectic liquid crystal having a large spontaneous polarization is used and when selective reflection of a cholesteric liquid crystal is used. This is particularly preferable in that a voltage can be applied to the liquid crystal layer.

[0023]

Embodiments of the present invention will be described below. For simplicity, a liquid crystal display element using a smectic liquid crystal material having a large spontaneous polarization will be described.

In a liquid crystal display device using a smectic liquid crystal material having a large spontaneous polarization, the cell gap is usually set to about 2 μm in order to take the SS state.
Accordingly, in order to prevent leakage between the first substrate provided with the active element and the wiring and the second substrate provided with the counter electrode facing the pixel electrode, an insulating film is formed on the counter electrode of the second substrate. Provision has been found to be effective.

Further, as a result of the study of the present inventors, it has been found that a large amount of leakage is caused by a chute between the convex electric wiring portion on the first substrate and the counter electrode of the second substrate. Specifically, it often occurs between a TFT having an inverted stagger structure and a counter electrode or between a signal line and a counter electrode. Further, the insulating film provided in a portion facing the pixel electrode causes a partial pressure of a pixel voltage to be applied to the liquid crystal layer,
It was also confirmed that the driving voltage was increased.

FIG. 1 is a view of the liquid crystal display device of the present invention as viewed from the film surface of the first substrate. In the structure shown in FIG. 1, a pixel electric potential is supplied to the pixel electrode 1 from the signal line 2 via the active element. Switching of the active element is performed by a potential supplied from the gate line 3. Here, the active element is a thin film transistor (TFT) composed of a source 4, a drain 5, and a gate 6. Since the TFT has an inverted staggered structure, the source 4 and the drain 5 among the structures provided on the first substrate have a particularly convex structure, and the signal line 2 follows the structure. .

According to the present invention, an insulating film is provided on the counter electrode facing the structurally convex portion. FIG. 2 shows a cross section of the structure of the liquid crystal display device according to one embodiment of the present invention. This cross section corresponds to a cross section taken along line AA ′ of the first substrate in FIG. 1 and a corresponding cross section of the second substrate.

In the liquid crystal display element shown in FIG. 2, a semiconductor film 104 is formed on a substrate 101 made of glass or plastic via a gate electrode 102 and a gate insulating film 103, and a source electrode is formed on the semiconductor film 104. 105
And a drain electrode 106 are formed.
T is configured. The drain electrode 106 of this TFT
Is connected to a pixel electrode 107 made of ITO. Further, an alignment film 108 is formed on the TFT and the pixel electrode 107.

A color filter composed of a color portion 109 and a black matrix 115 is formed on an opposite substrate 110, and a counter electrode 11 made of ITO is formed thereon in that order.
6. An insulating film 117 for preventing leakage between electrodes provided on the upper and lower substrates and an alignment film 118 are formed. In this case, the counter electrode 116 and the alignment film 118 are provided on the entire surface, but the insulating film 117 is formed on the TFT array substrate 1.
01 is provided only in a portion facing the source electrode 105 and the drain electrode 106.

The TFT array substrate 101 and the color filter substrate 110 as described above are opposed to each other with a spacer 112 interposed therebetween, and a liquid crystal layer 111 having a large spontaneous polarization is sandwiched between them. Polarizers 113 and 114 are arranged in a crossed Nicols state on the surface of the TFT substrate 101 and the color filter substrate 110 on the surface opposite to the facing surface.

Here, the spacers 112 are spacer balls dispersed on the substrate in order to keep the cell gap constant, but may be columnar spacers. However,
The spacer ball density is preferably 100 balls / mm ² or less. Spacer balls have a diameter of 1.5 μm
A material having a thickness of not less than 2.5 μm is used.

In the liquid crystal display element shown in FIG. 2 configured as described above, the insulating film provided in the conventional liquid crystal display element shown in FIG. It is provided only in a portion facing the electrode 105 and the drain electrode 106. Since this structure does not perform patterning of the counter electrode, it does not cause a problem in display performance due to insufficient charge supply capability such as crosstalk.

The insulating film 117 can be basically provided not only on the counter electrode facing the signal line 2 shown in FIG. 1 but also in a region excluding the pixel opening. The insulating film 117 thus formed is effective in preventing a short circuit between the two substrates. According to such a structure, FIG.
5 can be avoided, and the problem of display performance deterioration caused by the structure shown in FIG. 5 can be avoided.

Hereinafter, various types of the liquid crystal display device of the present invention using a smectic liquid crystal material having a large spontaneous polarization and providing an insulating film only on a portion of the counter electrode facing the convex structure on the TFT substrate. An example will be described. These embodiments are described for the purpose of facilitating understanding of the present invention, and various changes and modifications can be made without departing from the spirit of the present invention.

(Embodiment 1) FIG. 3 shows an outline of a pixel constituting an active matrix provided on an array substrate according to a first embodiment of the present invention. Note that, in the figure, the auxiliary capacitance is omitted.

The array substrate used in this embodiment conforms to the VGA specification, in which 640 pixel electrodes 201 composed of ITO are arranged vertically and (480 × 3) horizontally. Each pixel electrode is provided with a TFT which is a switching element,
A gate line 202 for supplying a gate voltage to the TFT;
Signal lines 203 for supplying signal voltages are arranged in a matrix. The TFT includes three terminals, a source 204, a gate 205, and a drain 206.

A liquid crystal cell as shown in FIG. 2 is constructed by combining the above array substrate and the color filter substrate so as to face each other. In FIG. 2, the black matrix 115 is provided at a position corresponding to the TFT.
In FIG. 3, a dotted line 207 indicates a black matrix end.

The liquid crystal display device shown in FIG. 2 was manufactured as follows. A color filter composed of a color part 109 and a black matrix 115, and a counter electrode 11 composed of ITO
6 (color filter substrate 11)
0) is prepared, and the black matrix end 207 shown in FIG.
An insulating film 117 made of SiO ₂ was formed in a region 3 μm inside (a region smaller than the region of the black matrix) by a mask sputtering method so as to have a thickness of 2000 Å.

On the other hand, a TFT comprising a gate electrode 102, a gate insulating film 103 made of silicon oxide or the like, a semiconductor film 104 made of amorphous silicon or the like, a source electrode 105 and a drain electrode 106 in contact with the semiconductor film 104, and an ITO A glass substrate (array substrate) 101 having a pixel electrode 107 made of was prepared.

On one surface of each of the array substrate 101 and the color filter substrate 110, a polyimide resin film (Optomer AL-1) serving as both an insulating film and an alignment film is provided.
051: Nippon Synthetic Rubber Co., Ltd.)
A film was formed by printing to a thickness of nm. After baking this in an oven, an orientation treatment by a cross rubbing operation was performed. Next, an epoxy adhesive for bonding was applied to predetermined positions of the array substrate 101 and the color filter substrate 110 by a conventional method.

Next, a resin-coated spacer ball 112 having a diameter of 2 μm is sprayed on the color filter forming surface of the color filter substrate 110 at a density of 100 pieces / mm ² so that the pixel portion and the electrode portion overlap. To
The two substrates 101 and 110 were joined together and bonded to form a liquid crystal cell.

Thereafter, the liquid crystal cell is placed in a vacuum container, and the liquid crystal cell is heated to 70 ° C. or more under vacuum, and a thresholdless antiferroelectric liquid crystal material MLC
0076 (manufactured by Mitsui Petrochemical Co., Ltd.)
The liquid crystal material 111 was filled in the liquid crystal cell by closing the injection port and returning the pressure outside the cell to atmospheric pressure. The melting point of this liquid crystal material is 70 ° C.

Next, when the liquid crystal cell was made into a module by a conventional method and the obtained liquid crystal display device was driven, each wiring and TFT formed on the array substrate were formed despite the narrow cell gap of 2 μm. Short-circuiting did not occur between the counter electrode formed on the color filter and the threshold value type antiferroelectric liquid crystal display device.

Comparative Example 1 Using the same color filter substrate and array substrate as in Example 1, a liquid crystal display device was produced as follows.

A color filter composed of a color part 309 and a black matrix 315 and a counter electrode 31 composed of ITO
6 on which the color filter substrate 31 is formed.
0) is prepared, and the entire surface of the display area of the counter electrode 316 of the color filter substrate 310 is coated with Si by a sputtering apparatus.
An insulating film 317 made of O ₂ was formed to have a thickness of 2000 Å.

On the other hand, a TFT comprising a gate electrode 302, a gate insulating film 303 made of silicon oxide or the like, a semiconductor film 304 made of amorphous silicon or the like, a source electrode 305 and a drain electrode 306 in contact with the semiconductor film 304, and an ITO A glass substrate (array substrate) 301 having a pixel electrode 307 made of was prepared.

On one surface of each of the array substrate 301 and the color filter substrate 310, a polyimide resin film (Optomer AL-1) which also serves as an insulating film and an alignment film is provided.
051: Nippon Synthetic Rubber Co., Ltd.)
A film was formed by printing to a thickness of nm. After baking this in an oven, an orientation treatment by a cross rubbing operation was performed. Next, an epoxy adhesive for bonding was applied to predetermined positions of the array substrate 301 and the color filter substrate 310 by a conventional method.

Next, a resin-coated spacer ball 312 having a diameter of 2 μm is sprayed on the color filter forming surface of the color filter substrate 310 so as to have a density of 100 / mm ² so that the pixel portion and the electrode portion overlap. To
The two substrates 301 and 310 were joined together and bonded to form a liquid crystal cell.

Thereafter, the liquid crystal cell is placed in a vacuum vessel, and the liquid crystal cell is heated to 70 ° C. or more under vacuum to form a thresholdless antiferroelectric liquid crystal material MLC as a liquid crystal material 311.
0076 (manufactured by Mitsui Petrochemical Co., Ltd.)
Then, the liquid crystal material 311 was filled in the liquid crystal cell by closing the injection port and returning the pressure outside the cell to atmospheric pressure. The melting point of this liquid crystal material is 70 ° C.

Next, when the liquid crystal cell was modularized by a conventional method and the obtained liquid crystal display device was driven, it was found that each wiring and TFT element formed on the array substrate had a small cell gap of 2 μm. Although no short circuit occurred with the counter electrode formed on the color filter substrate, the drive voltage increased about 1.8 times.

Example 2 Using the same color filter substrate and array substrate as in Example 1, a liquid crystal display device was manufactured as follows.

A color filter composed of a color part 109 and a black matrix 115 and a counter electrode 11 composed of ITO
6 (color filter substrate 11)
0) was prepared, and an insulating film made of TiO ₂ was formed to a thickness of 1800 nm on the counter electrode 116 of the color filter substrate 110 by a sputtering film forming apparatus.

Next, a phenol resin-based positive resist was applied so as to cover the entire surface of the insulating film. In addition to the signal lines 203 (width 10 μm) of the array substrate, a region facing 3 μm on both sides thereof and a region where the source 204, gate 205, and drain 206 constituting the TFT overlap each other are vertically arranged. After exposing with UV light having a center wavelength of 436 nm, except for a region opposed to a range (21 μm × 31 μm) where 3 μm is added to both the left and right, NMD-3 (manufactured by Tokyo Ohka Co., Ltd.) is used as a developing solution, The resist was removed.

Further, the insulating film exposed by the development was etched by dry etching using an RIE apparatus. Thereafter, the resist is removed by using a resist stripper (Hake-104: manufactured by Tokyo Ohka Co., Ltd.). Source 20 that constitutes
4, a range in which 3 μm is added to the area overlapping with the gate 205 and the drain 206 in both the upper, lower, left and right directions (21 μm)
(m × 31 μm) only.

On the other hand, a TFT comprising a gate electrode 102, a gate insulating film 103 made of silicon oxide or the like, a semiconductor film 104 made of amorphous silicon or the like, a source electrode 105 and a drain electrode 106 in contact with the semiconductor film 104, and an ITO A glass substrate (array substrate) 101 having a pixel electrode 107 made of was prepared.

On one surface of each of the color filter substrate 110 and the array substrate 101, polyimide resin films (RN1024: manufactured by Nissan Chemical Co., Ltd.) 108 and 118 serving both as an insulating film and an alignment film are formed to a thickness of 50 nm. The film was formed by printing. After baking this in an oven, it was rubbed in an anti-parallel manner to perform an orientation treatment. Next, an epoxy adhesive for bonding was applied to predetermined positions of the color filter substrate 110 and the array substrate 101 by a conventional method.

Next, spacer balls 112 made of silica having a diameter of 1.8 μm and having a density of 100 /
mm ² and the substrates 101 and 110 were bonded together so that the pixel portion and the electrode portion were overlapped to form a liquid crystal cell.

Thereafter, the liquid crystal cell is placed in a vacuum container, and a nematic liquid crystal material BL is used as the liquid crystal material 111.
035 (manufactured by Merck), the inlet is closed with the liquid crystal 111, and the pressure outside the cell is returned to the atmospheric pressure.
The liquid crystal material 111 was filled in the liquid crystal cell.

Next, when the liquid crystal cell was made into a module by a conventional method and the obtained liquid crystal display device was driven, the wirings and TFTs formed on the array substrate were formed despite the narrow cell gap of 1.8 μm. There was no short circuit between the device and the counter electrode formed on the color filter substrate, and a Pi twist type liquid crystal display device could be realized.

Example 3 Using the same color filter substrate as in Example 1 and an array substrate having an improved performance of the insulating film on the TFT, a liquid crystal display device was manufactured as follows.

A color filter composed of a color part 109 and a black matrix 115 and a counter electrode 11 composed of ITO
6 (color filter substrate 11)
0) was prepared, and an insulating film made of SiO ₂ was formed to a thickness of 2000 nm on the counter electrode 116 of the color filter substrate 110 by a CVD film forming apparatus.

Next, a phenolic resin-based positive resist was applied so as to cover the entire surface of the insulating film. Then, in addition to the signal line 203 (width 10 μm) of the array substrate, the center wavelength 43
After exposure with 6 nm UV light, NMD-3 was used as a developer.
(Tokyo Ohkasha Co., Ltd.), the exposed portion of the resist was removed.

Further, by treating with hydrofluoric acid, the insulating film exposed by the development was etched. Thereafter, the resist is removed using a resist stripper (Hake-104: manufactured by Tokyo Ohka Co., Ltd.), and the signal lines 203 (width 10 μm) on the array substrate are removed.
In addition to m), an insulating film was formed only in a region opposed to a range where 3 μm on both sides thereof was added.

On the other hand, a TFT comprising a gate electrode 102, a gate insulating film 103 made of silicon oxide or the like, a semiconductor film 104 made of amorphous silicon or the like, a source electrode 105 and a drain electrode 106 in contact with the semiconductor film 104, and an ITO A glass substrate (array substrate) 101 having a pixel electrode 107 made of was prepared. In the present array substrate, in particular, the thickness of an insulating film (not shown) formed on the TFT by using SiN _x or the like is set to be larger than normal.
By setting it to 0 nm, the insulation performance was improved.

On one surface of each of the color filter substrate 110 and the array substrate 101, a polyimide resin film (Optomer AL-1) which also serves as an insulating film and an alignment film is provided.
051: Nippon Synthetic Rubber Co., Ltd.)
A film was formed by printing to a thickness of nm. After firing in an oven, orientation was performed by a cross-rubbing operation. Next, an epoxy adhesive for bonding was applied to predetermined positions of the color filter substrate 110 and the array substrate 101 by a conventional method.

Next, a spacer ball 112 made of silica having a diameter of 2 μm was formed on the surface of the color filter substrate 110 and the array substrate 101 on which the alignment film was formed, at a density of 100 / mm.
² and the substrates 101 and 110 were bonded together so that the pixel portion and the electrode portion overlapped, thereby forming a liquid crystal cell.

Then, the liquid crystal cell is placed in a vacuum container, and the liquid crystal cell is heated to 70 ° C. or more under vacuum, and as a liquid crystal material 111, a thresholdless antiferroelectric liquid crystal material MLC is used.
0076 (manufactured by Mitsui Petrochemical Co., Ltd.)
The liquid crystal material 111 was filled in the liquid crystal cell by closing the injection port and returning the pressure outside the cell to atmospheric pressure. The melting point of this liquid crystal material is 70 ° C.

Next, when the liquid crystal cell was modularized by a conventional method and the obtained liquid crystal display device was driven, it was found that each wiring and TFT element formed on the array substrate had a small cell gap of 2 μm. In addition, no short-circuit occurred between the counter electrode formed on the color filter substrate and the thresholdless antiferroelectric liquid crystal display device could be realized.

Example 4 Using the same color filter substrate and array substrate as in Example 1, a liquid crystal display device was manufactured as follows.

A color filter composed of a color part 109 and a black matrix 115 and a counter electrode 11 composed of ITO
6 (color filter substrate 11)
0) was prepared, and an insulating film made of Ta ₂ O ₅ was formed to a thickness of 2000 nm on the counter electrode 116 of the color filter substrate 110 by a CVD film forming apparatus.

Next, a phenolic resin-based positive resist was applied so as to cover the entire surface of the insulating film. The source 204 and the gate 20 constituting the TFT of the array substrate
5. In the overlapping area of the drain 206,
A range with 3 μm added to both the top, bottom, left and right (21 μm × 31 μm)
m), after exposing with UV light having a center wavelength of 436 nm, using NMD-3 (manufactured by Tokyo Ohka Co., Ltd.) as a developing solution,
The exposed portion of the resist was removed.

Further, the insulating film exposed by the development was etched by dry etching using a CDE apparatus. Thereafter, the resist is removed using a resist stripper (Hake-104, manufactured by Tokyo Ohkasha Co., Ltd.)
Source 204, gate 205, drain 2 constituting T
In the area overlapping with 06, 3μ
The insulating film was formed only in the range (21 μm × 31 μm) to which m was added.

On the other hand, a TFT composed of a gate electrode 102, a gate insulating film 103 made of silicon oxide or the like, a semiconductor film 104 made of amorphous silicon or the like, a source electrode 105 and a drain electrode 106 in contact with the semiconductor film 104, and an ITO A glass substrate (array substrate) 101 having a pixel electrode 107 made of was prepared.

On one surface of each of the color filter substrate 110 and the array substrate 101, polyimide resin films (LX-1400: manufactured by Hitachi Chemical Co., Ltd.) 108 and 118, both serving as an insulating film and an alignment film, are provided with a thickness of 30 nm. A film was formed by printing. After baking this in an oven, orientation by parallel rubbing was performed. Next, an epoxy adhesive for bonding was applied to predetermined positions of the color filter substrate 110 and the array substrate 101 by a conventional method.

Next, resin spacer balls 112 having a diameter of 2 μm were formed on the surface of the color filter substrate 110 and the array substrate 101 on which the alignment films were formed, at a density of 100 / mm ^2.
The substrates 101 and 110 were bonded together so that the pixel portion and the electrode portion overlapped to form a liquid crystal cell.

Thereafter, the liquid crystal cell is placed in a vacuum container, and the nematic liquid crystal material ZL is used as the liquid crystal material 111.
Using I-5080 (manufactured by Merck), the liquid crystal material 111 was filled in the liquid crystal cell by closing the injection port with the liquid crystal 111 and returning the pressure outside the cell to atmospheric pressure.

Next, when the liquid crystal cell was modularized by a conventional method and the obtained liquid crystal display device was driven, it was found that each wiring and TFT element formed on the array substrate had a small cell gap of 2 μm. In addition, there was no short circuit between the counter electrode formed on the color filter substrate and the electric field control birefringence liquid crystal display device could be realized.

[0078]

As described above, according to the present invention,
In a liquid crystal display device having a narrow cell gap of 4.5 μm or less, such as a smectic liquid crystal material having a large spontaneous polarization or a liquid crystal display device using selective reflection of cholesteric liquid crystal, it is possible to selectively cover a region other than the pixel opening. By providing an insulating film, it is possible to avoid problems such as an increase in drive voltage and a decrease in display characteristics, and to effectively prevent a short circuit between substrates.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram of a liquid crystal display device according to one embodiment of the present invention, as viewed from a film surface of an array substrate.

FIG. 2 is a cross-sectional view illustrating a liquid crystal display device according to one embodiment of the present invention.

FIG. 3 is a plan view showing a relationship between a pixel electrode provided on an array substrate and a black matrix end of a color filter substrate.

FIG. 4 is a cross-sectional view showing a conventional liquid crystal display device.

FIG. 5 is a sectional view showing another example of a conventional liquid crystal display device.

[Explanation of symbols]

1,201 ... pixel electrode, 2,203 ... signal line, 3,202 ... gate line, 4,105,204,305 ... source electrode, 5,106,206,306 ... drain electrode, 6,102,205, 302 gate electrode, 101, 110, 301, 310 substrate, 103, 303 gate insulating film, 104 semiconductor film, 108, 118, 308, 318 alignment film, 109, 309 color part (color filter), 111, 311: liquid crystal material, 112, 312: spacer, 113, 114, 313, 314: polarizing plate, 115, 315: black matrix (color filter), 116, 316: counter electrode, 117, 317: insulating film.

Claims (4)

[Claims] A first substrate having a plurality of scanning lines, a plurality of signal lines, a plurality of switching elements formed near intersections of the scanning lines and the signal lines, and pixel electrodes connected to the switching elements; And a second substrate having a counter electrode and an insulating film formed on the counter electrode, the second substrate being opposed to the first substrate, and being sandwiched between the first and second substrates. A liquid crystal layer, wherein the insulating film is selectively formed in a region on the counter electrode that does not face the pixel electrode. 2. A first substrate having a plurality of scanning lines, a plurality of signal lines, a plurality of switching elements formed near an intersection of the scanning lines and the signal lines, and a pixel electrode connected to the switching elements. And a second substrate having a counter electrode and an insulating film formed on the counter electrode, the second substrate being opposed to the first substrate, and being sandwiched between the first and second substrates. A liquid crystal display device, wherein the insulating film is selectively formed in a region on the counter electrode facing the switching element. 3. A first substrate having a plurality of scanning lines, a plurality of signal lines, a plurality of switching elements formed near intersections of the scanning lines and the signal lines, and a pixel electrode connected to the switching elements. And a second substrate having a counter electrode and an insulating film formed on the counter electrode, the second substrate being opposed to the first substrate, and being sandwiched between the first and second substrates. A liquid crystal layer, wherein the insulating film is selectively formed in a region on the counter electrode facing the signal line or the scanning line. 4. The semiconductor device according to claim 1, wherein a gap between said first and second substrates is 4.5 μm or less.
3. The liquid crystal display device according to any one of items 3.