JP2000292797A - Liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase uniformity of a cell gap when external pressure is added and to prevent the production of vacuum bubbles at a low temp. in a liquid crystal display device having columnar spacers formed to keep the cell gap uniform. SOLUTION: This liquid crystal display device is equipped with a first substrate 1, a second substrate 2 facing the first substrate 1, a plurality of columnar spacers 22 almost homogeneously distributed between the first and second substrates to maintain the gap, a sealing material to seal and fix the periphery of the gap between the first and second substrates, and a liquid crystal layer 4 held between the first and second substrates. As for the columnar spacers 22, columnar spacers 22B having high hardness are disposed near and in the center region and columnar spacers 22A having low hardness are disposed in the peripheral region between the first and second substrates.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device, and more particularly, to a liquid crystal display device having a spacer for maintaining a uniform substrate gap.

[0002]

2. Description of the Related Art In general, a liquid crystal display element has a structure in which liquid crystal is held between a pair of electrode substrates which are arranged to face each other with a sealing material interposed therebetween. In such a liquid crystal display device, it is important to maintain a uniform substrate gap (cell gap) for obtaining good display characteristics. For this reason, conventionally, spacer particles have been dispersed on one substrate. Then, the other substrate is bonded on this.

However, in the case where such spacer particles are dispersed, the uniformity of the cell gap that can be secured is limited because the spacer particles are easily aggregated and uniform dispersion is difficult. there were. Further, depending on the position where the spacer particles are scattered, there is a problem that light leakage occurs and the contrast is reduced.

In order to solve these problems, there has been proposed a liquid crystal display device in which columnar spacers are arranged between substrates instead of spacer particles.

That is, in this liquid crystal display element, a columnar spacer made of, for example, an acrylic resin having a hardness of 70 durometer C is provided in a non-pixel portion on one substrate, for example, 50 to 50 μm.
100 mm ² uniformly arranged, the other substrate is pasted on it with a sealing material, and the liquid crystal is held between the substrates. The uniformity of the cell gap compared to the one where the spacer particles are scattered. And the contrast can be improved.

[0006]

In recent years, liquid crystal display elements have been widely used in various fields, taking advantage of the features of light weight, thinness, and low power consumption. 2. Description of the Related Art There is a device that includes a touch panel or the like on a screen and inputs signals with a pen or the like. In a liquid crystal display element used for such an application,
It is required that the uniformity of the cell gap be sufficiently ensured even when an external pressure is applied.

However, a liquid crystal display device using the above-mentioned columnar spacer has a sealing material for sealing between the substrates.
The use of a high-hardness resin material mixed with fibers causes a change in the cell gap when an external pressure is applied to the central part of the display screen from the peripheral part to the outside. is there. In other words, due to the effect of the high-hardness sealing material, the cell gap in the peripheral portion hardly changes even when an external pressure is applied, but the central portion is hardly affected by the sealing material. As a result, the uniformity of the cell gap is impaired.

As a countermeasure, it is conceivable to increase the arrangement density of the spacers.
At low temperatures, the shrinkage of the liquid crystal does not always coincide with the shrinkage of the spacer, so that a vacuum bubble is likely to be generated, causing a problem of deteriorating the display quality.

The present invention has been made in view of the above-mentioned circumstances, and a liquid crystal in which even when an external pressure is applied, the uniformity of the cell gap is sufficiently ensured and the generation of vacuum bubbles at low temperatures is prevented. It is an object to provide a display element.

[0010]

According to a first aspect of the present invention, there is provided a liquid crystal display device comprising: a first substrate; and a second substrate opposed to the first substrate. ,
A plurality of spacers that are disposed approximately evenly between the first and second substrates and maintain a gap therebetween; a seal member that seals and fixes a periphery between the first and second substrates; In a liquid crystal display device having a liquid crystal layer held between the first and second substrates, a spacer having a higher hardness than the peripheral portion is disposed near a center between the first and second substrates. It is characterized by having.

According to the liquid crystal display device having the above-described structure, the spacer having a higher hardness than the peripheral portion is disposed near the center between the first and second substrates. , The change in the cell gap when an external pressure is applied can be made substantially the same between the central portion that is hardly affected by the sealing material and the peripheral portion that is affected by the sealing material. Therefore, the uniformity of the cell gap during the action of the external pressure is sufficiently ensured, and the generation of vacuum bubbles at a low temperature is also prevented.

[0012]

Embodiments of the present invention will be described below in detail with reference to the drawings. In the following embodiments, the same elements will be denoted by the same reference symbols, without redundant description.

FIG. 1 is a view schematically showing a sectional structure of an active matrix type liquid crystal display device according to a first embodiment of the present invention, and FIG. 2 is an enlarged view of a part of the liquid crystal display device. FIG.

As shown in these figures, the liquid crystal display device according to this embodiment has an array substrate 1 and an array substrate 1.
And a sealing material 3 made of a fiber-filled epoxy resin having a hardness of 85 durometer C for sealing and fixing the periphery between these substrates, and a liquid crystal layer 4 held between the substrates. It has. Although not shown, the liquid crystal display element is electrically connected to a drive circuit unit and has a surface light source device on the array substrate 1 side.

The array substrate 1 has a rectangular transparent glass substrate (370 mm × 470 mm × 0.7 mm) 5 on which a number of signal lines 6 parallel to each other and these signal lines A large number of scanning lines (not shown) substantially orthogonal to 6 are provided in a matrix. The deflection amount of the glass substrate 5 due to its own weight is about 10 mm when the holding width is 550 mm and about 20 mm when the holding width is 550 mm.

In each area surrounded by the signal lines 6 and the scanning lines, a transparent pixel electrode 7 made of indium tin oxide (hereinafter, referred to as ITO) is formed. In the vicinity of the intersection between the scanning line 6 and each scanning line, a thin film transistor (hereinafter, referred to as TFT) 8 having an inverted staggered structure using the scanning line itself as a gate electrode 7 as a switching element is provided.

More specifically, in the TFT 8, the gate electrode 7 formed on the glass substrate 5 is covered with a gate insulating film 9 made of a silicon nitride (SiNx) film, and hydrogenated amorphous silicon (a-Si: H) A structure in which a semiconductor layer 10 made of a thin film is formed, and a channel protective film 11 made of a silicon nitride (SiNx) film is formed thereon. A semiconductor layer made of an a-Si: H thin film is formed on the channel protective film 11 and the semiconductor layer 10 via a semiconductor layer 12 made of a phosphorus-doped low-resistance hydrogenated amorphous silicon (n ⁺ a-Si: H) thin film. A source electrode 13 electrically connected to 10 and a drain electrode 14 integrated with the signal line 6 are arranged. The source electrode 13 is also electrically connected to the pixel electrode 7.

Although not shown, auxiliary capacitance lines are arranged on the glass substrate 4 substantially in parallel with the scanning lines, and these auxiliary capacitance lines and the pixel electrodes 7 are arranged to face each other via the gate insulating film 9. And constitute an auxiliary capacity.

The TFTs 8, the pixel electrodes 7, the scanning lines, the signal lines 6 and the like having the above structure are covered with a transparent alignment film 15 made of polyimide or the like.

On the other hand, the counter substrate 2 includes a transparent glass substrate (370 mm × 470 mm × 0.7 mm) 16, and the color filter 17 covers the entire inner surface of the glass substrate 16.
And a transparent counter electrode 18 made of ITO in this order, and a transparent alignment film 19 made of polyimide or the like is further formed thereon. 2, 21 in FIG.
Indicates a polarizing plate.

A rectangular column having a rectangular cross section of 14 μm in length and 8 μm in width, which holds a cell gap between the array substrate 1 and the counter substrate 2, is provided between the array substrate 1 and the counter substrate 2. Column spacer 22 consisting of 952
The pixels are uniformly arranged at a density of μm ² / mm ² , one for every four pixels.

More specifically, each columnar spacer 22 has a columnar body 23 protruding from the inner surface of the counter electrode 18 of the counter substrate 2, and the surface thereof is covered with an alignment film 19. Further, the tip of the columnar body 23 contacts the alignment film 15 on the array substrate 1 side via the alignment film 19 and faces the scanning line.

In the present embodiment, of these columnar spacers 22, the columnar body 23A of the columnar spacer 22A located within approximately 30 mm from the inner end of the sealing material 3 is used.
Is formed of an acrylic resin having a hardness of 70 durometer C, and the columnar body 23B of the columnar spacer 22B located on the inner side thereof is formed of an acrylic resin having a hardness of 85 durometer C.

In the liquid crystal display device having such a configuration, the columnar spacers 22B having a higher hardness than the peripheral columnar spacers 22A are arranged at the center, so that the cell gap when an external pressure is applied is increased. However, there is almost no change between the peripheral portion near the sealing material 3 and the central portion away from the sealing material 3, and the uniformity of the cell gap is sufficiently ensured, and good display quality is maintained. Moreover, the columnar spacer 2 at the center
Since it is not necessary to increase the arrangement density of 2B than the arrangement density of the columnar spacers 22A in the peripheral part, it is possible to prevent the generation of vacuum bubbles at low temperatures.

The columnar spacers 22 arranged at the peripheral portion
The hardness and the arrangement region of A and the columnar spacers 22B arranged at the center are appropriately set according to the substrate area, the type of the sheath material 3, and the like, and are not particularly limited to the above examples. In the present invention, the columnar spacer 2
It is also possible to further subdivide the arrangement region 2 so that the hardness gradually increases from the outside toward the center.

The material for forming the columnar spacer 22 is not particularly limited to the above-mentioned acrylic resin, and the shape of the columnar spacer 22 may be circular or elliptical in cross section parallel to the glass substrates 5 and 16. Or a polygon such as a square, a rectangle, or a triangle.

[0027] The arrangement density of the columnar spacer ^22, 5 0 0
The range of 3000 μm ² / mm ² is desirable, and within such a range, the cell gap can be kept uniform and the generation of vacuum bubbles at low temperatures can be sufficiently suppressed. That is, the density of the columnar spacers 22 is 5
When it is less than 00μm ² / mm ^2, it becomes difficult to maintain a uniform cell gap, 3000μm ² / mm ² in the opposite
If it exceeds 300, vacuum bubbles may be generated. A more desirable range of the arrangement density is 700 to 2000 μm ² / mm ^2.
Range.

And, such a columnar spacer 22 is
In order not to damage the effective display area, it is desirable to dispose it in a non-display area such as on a wiring of a substrate and to arrange as evenly as possible.

Further, in the above-described embodiment, the columnar body 23 constituting the columnar spacer 22 is provided on the inner surface of the counter electrode 18 of the counter substrate 2, but may be provided on the inner surface of the color filter 17. Good. Further, the columnar body 23 may not be separately provided, but may be configured by a laminate of each color of the color filter 17.

In the above-described embodiment, the column spacer 22 is provided on the counter substrate 2 side.
It may be configured to be arranged on the side. Further, the array substrate 1
The column spacer 22 may be arranged on each of the counter substrate 2 and the counter substrate 2. In this case, the columnar spacer 22A and the columnar spacer 22B in the peripheral portion may be provided on different substrates. Further, the columnar spacers 2 provided on each substrate are provided.
2 may be superimposed to keep the cell gap.

Further, the above-described embodiment is an example in which the present invention is applied to an active matrix type liquid crystal display device having an inverted staggered structure TFT. It goes without saying that the present invention can be applied to various liquid crystal display elements including the element.

Hereinafter, an example in which the present invention is applied to an active matrix type liquid crystal display device having a TFT having a positive stagger structure will be described as a second embodiment with reference to the drawings.

FIG. 3 is a diagram schematically showing a cross-sectional structure of an active matrix type liquid crystal display device according to a second embodiment of the present invention, and FIG. 4 is an enlarged view of a part of the liquid crystal display device. FIG.

As shown in these figures, the liquid crystal display element according to this embodiment has an array substrate 1 and an array substrate 1.
And a sealing material 3 made of a fiber-filled epoxy resin having a hardness of 85 durometer C for sealing and fixing the periphery between these substrates, and a liquid crystal layer 4 held between the substrates. In that the liquid crystal display element is electrically connected to the drive circuit section and the array substrate 1
In the point that the surface light source device is provided on the side and the polarizing plates 20 and 21 are provided outside the two substrates 1 and 2,
This is the same as the embodiment.

In this embodiment, the opposing substrate 2 is formed with a transparent opposing electrode 18 made of ITO over the entire inner surface of a transparent glass substrate (370 mm × 470 mm × 0.7 mm) 16 and made of polyimide or the like. It has a configuration in which a transparent alignment film 19 is formed.

On the other hand, the array substrate 1 is formed by forming a silicon oxide (SiO 2) film and a silicon nitride (SiNx) on a rectangular transparent glass substrate (370 mm × 470 mm × 0.7 mm) 5.
An undercoating layer 30 having a two-layer structure of a film is disposed, and a TFT 31 having a positive stagger structure is provided thereon as a switching element.

More specifically, the TFT 31
Is a semiconductor active layer (channel) 3 made of a polysilicon (p-Si) thin film on the undercoating layer 30.
2. A high-concentration impurity region 33 made of a low-resistance phosphorus-doped polysilicon (n + p-Si) thin film serving as a source / drain was formed, these were covered with a gate oxide film 34, and a gate electrode 35 was further provided thereon. Having a structure. Note that the scanning lines (not shown) are formed in the same step as the gate electrode 35. Scan line and gate oxide film 34
A signal line 36 having a two-layer structure of Mo and Al is arranged thereon, and the signal line 36 is formed through a first contact hole 38 penetrating through an interlayer insulating film 37 and a gate oxide film 34. 33.

On the signal line 36, an inorganic insulating film 39 having a two-layer structure of a silicon oxide (SiO 2) film and a silicon nitride (SiNx) film, and a stripe-shaped organic resin of three colors of red, blue and green are provided. Are provided in order, and a second contact hole 40 is formed in the inorganic insulating film 39 and the color filter 17. Further, a transparent pixel electrode 7 made of ITO is arranged on the color filter 17, and the pixel electrode 7 is electrically connected to the signal line 36. These pixel electrodes 7
The color filter 17 is covered with a transparent alignment film 15 made of polyimide or the like.

In a region where the pixel electrode 7 is not formed between the array substrate 1 and the counter substrate 2, a columnar spacer for maintaining a cell gap between the array substrate 1 and the counter substrate 2 is provided. 22 are evenly arranged at a density of 1400 μm ² / mm ² .

More specifically, each columnar spacer 22 is formed by a columnar body 2 protruding from the color filter 17 of the array substrate 1.
3, the surface of which is covered with an alignment film 15.

In the present embodiment, of these columnar spacers 22, the columnar members 23A of the columnar spacers 22A located within approximately 30 mm from the inner end of the sealing material 3 are used.
Is formed of an acrylic resin having a hardness of 70 durometer C, and the columnar body 23B of the columnar spacer 22B located on the inner side thereof is formed of an acrylic resin having a hardness of 85 durometer C.

In the liquid crystal display device thus constructed, similarly to the first embodiment, the columnar spacer 22B having a higher hardness than the peripheral columnar spacer 22A at the center is arranged. , The cell gap when external pressure is applied is
There is almost no change between the peripheral portion near the sealing material 3 and the central portion away from the sealing material 3, so that the uniformity of the cell gap is sufficiently ensured and good display quality can be obtained. Moreover,
Since it is not necessary to increase the arrangement density of the columnar spacers 22B in the central part more than the arrangement density of the columnar spacers 22A in the peripheral part, it is possible to prevent the occurrence of vacuum bubbles at low temperatures.

[0043]

As described above, according to the liquid crystal display device of the present invention, the change in the cell gap when an external pressure is applied can be reduced without increasing the arrangement density of the spacers. Since the central part that is hardly affected and the peripheral part affected by the sealing material can be almost the same,
The uniformity of the cell gap at the time of the external pressure can be sufficiently ensured, and the generation of vacuum bubbles at a low temperature can be prevented.

[Brief description of the drawings]

FIG. 1 is a view schematically showing a cross-sectional structure of an active matrix type liquid crystal display device according to a first embodiment of the present invention.

FIG. 2 is an enlarged sectional view showing a part of the liquid crystal display device of FIG. 1;

FIG. 3 is a diagram schematically showing a cross-sectional structure of an active matrix type liquid crystal display device according to a second embodiment of the present invention.

FIG. 4 is an enlarged cross-sectional view showing a part of the liquid crystal display element of FIG. 3;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Array board 2 ... Counter board 3 ... Sealing material
4: Liquid crystal layer 5, 16: Glass substrate 6, 36: Signal line 7: Pixel electrode 8, 31: TFT 22: Columnar spacer 22A ...
Low hardness column spacer 22B… High hardness column spacer Applicant Toshiba Corporation Attorney Patent Attorney Su
Saichi Yama

Continued on the front page F-term (reference) 2H089 JA11 LA09 LA16 MA04X MA05Y NA14 NA24 NA37 NA56 NA60 PA06 PA08 QA14 RA05 TA05 TA09 2H092 JA26 JA29 JA38 JA42 JA44 JB13 JB23 JB32 JB33 JB38 JB58 KA05 KA07 KA12 MA18 MA18 MA05 MA08 MA27 MA35 MA41 NA04 NA25 NA27 PA02 PA03 5C058 AA08 AB06 BA35 5C094 AA03 AA36 AA47 AA48 AA54 AA55 AA60 BA03 BA43 CA19 DA12 EA04 EA05 EA07 EB02 EC02 EC03 FB01 FB15 GB10 JA01 JA20

Claims (8)

[Claims] 1. A first substrate, a second substrate opposed to the first substrate, and a plurality of substrates distributed substantially uniformly between the first and second substrates to maintain a gap therebetween. A liquid crystal display element comprising a spacer, a sealing material for sealing and fixing the periphery between the first and second substrates, and a liquid crystal layer held between the first and second substrates; A liquid crystal display device, wherein a spacer having a higher hardness is disposed near a center between the first and second substrates than at a peripheral portion thereof. 2. The liquid crystal display device according to claim 1, wherein the sealing material has a durometer C hardness of 80 to 90. 3. The durometer C hardness of the high-hardness spacer disposed closer to the center between the first and second substrates is 80 to 90. Liquid crystal display element. 4. The spacer according to claim 1, wherein the spacer is a columnar spacer integrally formed on at least one inner surface of the first and second substrates. 2. The liquid crystal display device according to claim 1. 5. The columnar spacer is 500 to 3000.
5. The liquid crystal display device according to claim 4, wherein the liquid crystal display device is arranged at a density of μm ² / mm ² . 6. The columnar spacer pair is 700 to 200.
5. The liquid crystal display device according to claim 4, wherein the liquid crystal display device is arranged at a density of 0 μm ² / mm ² . 7. At least one of the pair of substrates includes a plurality of signal lines and scanning lines arranged in a matrix and pixel electrodes arranged via switching elements. The liquid crystal display device according to claim 1. 8. The liquid crystal display device according to claim 7, wherein the pair of columnar spacers is disposed so as to overlap any one of the signal line, the scanning line, and the switching element.