JPH11264987A - Liquid crystal display - Google Patents

Abstract

(57) [Summary] In a liquid crystal display device, generation and progress of a progressive bubble, which is a factor that significantly deteriorates display quality, are prevented. A pair of substrates is kept convex by reducing the diameter of a spacer in a sealing material to be smaller than the spherical diameter of a gap material in a liquid crystal layer, and the substrates return to a flat surface. A positive pressure is always applied to the liquid crystal layer 2 by the force. The conditions for selecting the gap material 5 and the spacer 3 are as follows. 0 μm <XG−XS ≦ 0.3 μm (where XG is the sphere diameter of the gap material and XS is the diameter of the spacer.)

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a liquid crystal display device, and more particularly to a condition of a gap material between substrates in a liquid crystal display.

[0002]

2. Description of the Related Art In a liquid crystal display device, a gap material is dispersed between a pair of substrates having electrodes, and a sealing material with spacers is arranged around the periphery of the substrates to form a uniform cell gap. Liquid crystal is sealed in this cell.

As a liquid crystal display device having such a structure, there is, for example, a device disclosed in Japanese Patent Application Laid-Open No. 3-80224. Hereinafter, the structure of a conventional liquid crystal display device will be described with reference to the drawings.

FIG. 4 is a sectional view of a conventional liquid crystal display device using a gap material and a sealing material with a spacer.

As shown in FIG. 1, in this liquid crystal display device, a gap material 5 is dispersed between a pair of substrates 1 having pixel electrodes 8, and a sealing material having a spacer 3 is provided around the periphery of the substrate 1. 4, the cell gap is formed uniformly, and the liquid crystal 2 is sealed in the cell.

In the above-mentioned conventional liquid crystal display device, XG = XS (where XG is the sphere diameter of the gap material and XS is the diameter of the spacer) as a selection condition of the gap material and the spacer.

FIG. 5 shows a liquid crystal display device in which a gap material is dispersedly arranged between a pair of substrates having a color filter formed on at least one glass substrate, and a sealing material with a spacer is provided around the periphery of the substrate. Is shown.

As shown in FIG. 1, a color filter 7 is formed on at least one glass substrate 1, a gap material 5 is dispersedly arranged on one of the substrates, and a sealing material 4 with a spacer 3 is provided around the periphery. Are arranged to form a uniform cell gap, and the liquid crystal 2 is sealed in this cell. In addition, the color filter 7 often has a different thickness for each of the RGB colors or is formed such that the black matrix 6 protrudes, and the color filter 7 has an uneven shape.

In a liquid crystal display device having such a color filter 7, the cell thickness in the display area is determined by the thickness of the most convex portion 6, which is the thickest part of the color filter 7, and the spherical diameter of the gap material. Is determined by the sum of Therefore,
In the above-mentioned conventional liquid crystal display device, the selection conditions of the gap material and the spacer are as follows: XG + hBM = XS (where XG is the ball diameter of the gap material, XS is the diameter of the spacer, and hBM is the glass substrate of the most convex portion 6 of the color filter 7. Height from the surface).

[0010]

As described above, in the conventional liquid crystal display device, the cell thickness in the display area is designed to be equal to the cell thickness of the sealing material portion including the spacer. . Therefore, the cross-sectional shape of the liquid crystal display device is ideally such that the pair of substrates are parallel as shown in FIG. In this case, since there is no deformation of the substrate,
No internal pressure is generated in the liquid crystal cell due to the deformation of the substrate.

Further, as shown in FIG. 3C, the pair of substrates constituting the liquid crystal display device is formed into a concave shape due to a pressure at the time of bonding the pair of substrates or a manufacturing error of the spacer, the gap material, and the color filter. May be.
When the pair of substrates becomes concave as described above, a force acts to return the substrates from the concave to a flat surface, so that the pressure inside the liquid crystal cell becomes a negative pressure.

In a liquid crystal display device, minute bubbles may be generated due to distortion of the liquid crystal display cell due to external pressure, pressurization by attaching a polarizing plate, various repairs, various pressures or vibrations applied to the device. is there. As long as these minute bubbles exist alone, there is often no problem in display quality.

However, when the internal pressure in the liquid crystal cell is 0 or negative pressure as described above, the fine bubbles generated as described above expand as progressive bubbles, and when the size becomes such that it can be visually checked, The display quality deteriorates significantly,
The production yield of the liquid crystal display device is reduced. In addition, since the bubbles have a progressive property, the reliability of the liquid crystal display device is also significantly reduced.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to maintain the internal pressure of a liquid crystal cell at a positive pressure by optimally selecting dimensions of a spacer and a gap material in a liquid crystal display device. Another object of the present invention is to provide a liquid crystal display device capable of reducing the generation of progressive bubbles.

[0015]

According to a first aspect of the present invention, there is provided a liquid crystal display device comprising: a gap material disposed between a pair of substrates; In a liquid crystal display device provided with a sealing material having a spacer at a peripheral portion, as a selection condition of the gap material and the spacer, 0 μm <XG−XS ≦ 0.3 μm (where XG is the ball diameter of the gap material and XS is And a spacer that satisfies the following condition.

According to this means, the cell thickness in the effective area of the liquid crystal cell becomes larger than the cell thickness of the sealing material portion in the peripheral portion of the substrate, and the pair of substrates is formed in a convex shape. . According to the above configuration, the pair of substrates are formed in a convex shape, and the internal pressure of the liquid crystal cell is maintained at a positive pressure by using a force acting to return the substrate from the convex shape to a flat surface,
It has the effect of reducing the generation of progressive bubbles.

Further, in the liquid crystal display device according to the present invention, a gap material is dispersedly arranged between a pair of glass substrates having a color filter formed on at least one of the glass substrates, and a sealing material with a spacer is provided around the periphery. In the liquid crystal display device provided with, as the selection conditions of the gap material and the spacer, 0 μm <XG + hBM-XS ≦ 0.3 μm (where XG is the sphere diameter of the gap material, XS is the diameter of the spacer, and hBM is the most convex of the color filter. (The height of the portion from the glass substrate surface) is used.

According to this means, even when a color filter having irregularities is used, the cell thickness in the effective area of the liquid crystal cell becomes thicker than the cell thickness of the peripheral sealing material portion, and a pair of the liquid crystal cells is formed. The substrate is made convex. According to the above configuration, a pair of substrates in which a color filter is arranged on at least one of the substrates is arranged in a convex shape, and the liquid crystal cell uses a force acting to return the substrate from the convex shape to a flat surface. This has the effect of maintaining the internal pressure at a positive pressure and reducing the generation of progressive bubbles.

[0019]

Embodiments of the present invention will be described below with reference to the drawings. The present invention relates to TN type, STN type, GH
Various types of known liquid crystal display devices such as molds, watches, calculators, etc., used for a relatively small area display, to a large capacity panel used for a personal computer display, a small television, etc. Applicable.

FIG. 1 is an enlarged sectional view of a part of the liquid crystal display device according to the first embodiment of the present invention.

As shown in FIG.
A pair of substrates 1 opposed to each other, a liquid crystal layer 2 sandwiched between the pair of substrates 1, a sealing material 4 arranged to surround the liquid crystal layer 2, a spacer 3 existing in the sealing material 4, And a gap material 5 existing in the layer 2. In addition,
Depending on the liquid crystal display device, a polarizing plate may be arranged outside the substrate 1.

The substrate 1 is generally made of glass.
The pixel electrode 8 is mainly provided on each of the opposing surfaces
Formed by a method such as thin film formation and photolithography. Further, a driving element such as a transistor or a diode may be formed in addition to the pixel electrode 8.

As the sealing material 4, an epoxy-based adhesive or a UV-curable adhesive is generally used. The sealing material 4 is formed on one of the opposing substrates 1 by, for example, a printing method, thereby defining the area of the liquid crystal layer 2 together with the opposing substrate 1.

A spacer 3 is mixed in the sealing material 4 in order to keep the cell gap of the opposing substrate 1 constant. The spacer 3 is generally made of glass as a material, and has a shape such as a ball shape or a fiber shape.

The gap member 5 is generally a resin ball, and is mainly made of a divinylbenzene polymer. The gap material 5 is the substrate 1 on which the sealing material 4 is printed, or
The sealing material 4 is scattered on one or both of the substrates 1 on which no printing is performed. As a method of distributing the gap material 5, an electrostatic dispersing method of charging the gap material 5 with one of positive and negative charges is generally used.
The gap material 5 exists in the liquid crystal layer 2, and is intended to maintain a constant gap between the substrates 1 facing each other similarly to the spacer 3.

Here, the spacer 3 in the sealing material 4 is
It is arranged at the position where the sealing material 4 is arranged, that is, at the periphery of the substrate 1, thereby maintaining the cell gap at the periphery of the substrate 1. On the other hand, gap material 5
Is provided in the display area of the liquid crystal display device so as to maintain a gap between the pair of substrates 1, and thus is disposed in a region inside the seal material 4 of the substrate 1. In the liquid crystal display device according to the present embodiment, the diameter of the spacer 3 disposed in the peripheral portion of the substrate 1 is smaller than the spherical diameter of the gap material 5 disposed in the region of the liquid crystal layer 2 of the substrate 1, The cell gap in the region of the liquid crystal layer 2 is larger than the cell gap in the peripheral portion of the substrate 1. As a result, FIG.
As shown in (A), the central region of the substrate is formed in a convex shape, and a stress returning to the plane of the substrate can be generated. That is, it is possible to generate a stress that compresses the liquid crystal layer 2 sandwiched between the pair of substrates 1, thereby keeping the internal pressure of the liquid crystal cell at a positive pressure and reducing the generation of progressive bubbles.

It is desirable that the diameter of the spacer 3 and the spherical diameter of the gap member 5 satisfy the following expression.

0 μm <XG−XS ≦ 0.3 μm (where XG is the diameter of the sphere of the gap material and XS is the diameter of the spacer.) This is a condition of XG−XS ≦ 0 μm. 3 (B) and FIG.
As shown in (C), the internal pressure of the liquid crystal cell does not become a positive pressure, and the effect on the progressive bubbles cannot be expected. On the other hand, under the condition of XG-XS> 0.3 μm, it is possible to make the internal pressure of the liquid crystal cell a positive pressure, but display unevenness around the display area of the liquid crystal display device becomes remarkable, and the display quality becomes poor. This is because it may cause deterioration. Therefore, by using the spacer 3 and the gap material 5 that satisfy the above equation, it is possible to reduce the generation of advancing bubbles without deteriorating display quality due to display unevenness.

The number of the gap members 5 to be scattered in this embodiment is desirably 50 pieces / mm ² or more as the density per panel area. More preferably, 1
It is not less than 00 pieces / mm ^{2 and not} more than 300 pieces / mm ² . This is because when the number of dispersal is 50 pieces / mm ² or less, the sectional shape of the panel of the liquid crystal display device is as shown in FIG.
As shown in (C), the effect on progressive bubbles cannot be expected. On the other hand, when the scattering number is 300 pieces / mm ² or more, the presence of the gap material is visually confirmed, which may cause deterioration of the display quality of the liquid crystal display device.

FIG. 2 is an enlarged sectional view of a part of a liquid crystal display device according to a second embodiment of the present invention. The liquid crystal display device according to the second embodiment is obtained by forming a color filter 7 on one of the substrates 1 in the first embodiment.

When the color filter 7 has a different film thickness for each color of RGB, when a black matrix (light-shielding portion) is formed of a resin-based material, or when a light-shielding portion is formed by overlapping of RGB, this color filter is used. The convex portion in the filter 7 is formed to be thicker. In FIG. 2, reference numeral 6 denotes the most convex portion of the color filter 7 having the unevenness, which is the portion having the largest film thickness.

In the present embodiment, the diameter of the spacer 3 is smaller than the sum of the spherical diameter of the gap member 5 and the height of the most convex portion 6 from the surface of the substrate 1. Thereby, similarly to the first embodiment, a stress returning to the plane of the substrate 1 can be generated. Therefore, the internal pressure of the liquid crystal cell can be maintained at a positive pressure, and the generation of progressive bubbles can be reduced.

It is desirable that the gap material 5 and the spacer 3 satisfy the following equations.

0 μm <XG + hBM−XS ≦ 0.3 μm (where XG is the sphere diameter of the gap material, XS is the diameter of the spacer, and hBM is the substrate 1 of the most convex portion 6 of the color filter 7.
Height from the plane. ).

As described in the first embodiment, by satisfying the above expression, in a liquid crystal display device using a color filter, generation of advancing bubbles can be prevented without deteriorating display quality due to display unevenness. Can be reduced.

As in the first embodiment, the number of the gap members 5 to be scattered in the present embodiment is similar to that in the first embodiment, from the viewpoint of the effect on the progressive bubbles and the prevention of the deterioration of the display quality of the liquid crystal display device. The density per area is desirably 50 pieces / mm ² or more. More preferably,
It is 100 pieces / mm ² or more and 300 pieces / mm ² or less.

[0037]

According to the present invention, by forming a pair of substrates into a convex shape, the internal pressure of the liquid crystal cell is made positive by utilizing the force acting to return the substrates from the convex shape to a flat surface. Keep,
This has the effect of reducing the generation of progressive bubbles.

[Brief description of the drawings]

FIG. 1 is an enlarged sectional view of a part of a liquid crystal display device according to a first embodiment of the present invention.

FIG. 2 is an enlarged sectional view of a part of a liquid crystal display device according to a second embodiment of the present invention.

3A is a conceptual diagram of a cross-sectional shape of a liquid crystal display device according to the present invention, and FIGS. 3B and 3C are conceptual diagrams of a cross-sectional shape of a conventional liquid crystal display device.

FIG. 4 is an enlarged sectional view of a part of a conventional liquid crystal display device.

FIG. 5 is an enlarged sectional view of a part of a conventional liquid crystal display device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Substrate 2 ... Liquid crystal layer 3 ... Spacer 4 ... Sealing material 5 ... Gap material 6 ... Most convex part 7 ... Color filter 8 ... Pixel electrode

Claims (2)

[Claims] 1. A liquid crystal display device comprising: a gap material dispersedly arranged between a pair of substrates; and a sealing material having a spacer at a peripheral portion of the substrate, wherein a selection condition of the gap material and the spacer is 0 μm < A liquid crystal display device using a gap material and a spacer that satisfies XG-XS ≦ 0.3 μm (where XG is the ball diameter of the gap material and XS is the diameter of the spacer). 2. A liquid crystal display device comprising: a gap material dispersedly arranged between a pair of glass substrates each having a color filter formed on at least one glass substrate; and a sealing material provided with a spacer around a periphery of the glass substrate. The selection conditions of the gap material and the spacer are as follows: 0 μm <XG + hBM-XS ≦ 0.3 μm (where XG is the sphere diameter of the gap material, XS is the diameter of the spacer, and hBM is the distance from the glass substrate surface of the most convex portion of the color filter. A liquid crystal display device using a gap material and a spacer satisfying the following condition.