JPH05100232A - Liquid crystal display device - Google Patents

Abstract

PURPOSE:To prevent a display screen from being distorted owing to the thermal expansion of a substrate. CONSTITUTION:Interdigital electrodes 24 are formed on electrode substrates 11 and 12 by arranging plural electrode parts 25 in parallel respectively. Plural 1st spacers 13 are formed at space parts 26 between the electrode parts on the 1st electrode substrate 11 by setting resin and then 2nd spacers 14 are formed between the 1st spacers 13 or at space parts 26 on the 2nd electrode substrate 12. When the liquid crystal display device is assembled, those electrode substrates 11 and 12 are set opposite each other in specific relation and then the 2nd spacers 14 are set to adhere the substrates 11 and 12. The 1st spacers 13 are provided on the 1st electrode substrate 11, and completely set and used to prevent a nonreversible display irregularity due to the movement of the spacers, etc. When the 2nd spacers 14 are set, the electrode substrates 11 and 12 are adhered to disperse deflection due to expansion, thereby eliminating the cause of local deterioration and a defect in display performance.

Description

Detailed Description of the Invention

[Object of the Invention]

[0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device using a flexible heat resistant film on a transparent substrate, and more particularly to a spacer structure for securing a space for liquid crystal.

[0003]

2. Description of the Related Art Liquid crystal display devices have characteristics such as thinness, light weight and low power consumption, and have come to be used in various fields. And recently, as a liquid crystal device,
It has been desired to further reduce the weight and thickness of a light-transmissive substrate by using a flexible heat-resistant plastic film (hereinafter referred to as a plastic film). In addition, as for the use of such a thin liquid crystal display device, the demand is expanding from the conventional segment type to office automation.

Here, a liquid crystal display device using a plastic film as a substrate is considerably lighter than a conventional one using glass as a substrate, and since the substrate can be processed from roll to roll, the productivity is also improved. It has the advantage of being good. The plastic film used as the substrate includes polyethylene terephthalate (hereinafter PET) and polyether sulfone (hereinafter PE).
S) and the like, and liquid crystal display devices using them are known, for example, from Japanese Patent Laid-Open No. 59-37527.

By the way, the PET or PES used for such a substrate has a larger linear expansion coefficient than that of conventionally used glass. In the case of PET, the linear expansion coefficient is 1.5 to 2 as compared with glass. It is 0.0 times larger and has the property of expanding when humidity increases.

Although such a property hardly causes a problem when the display screen is small, in a large display device for office automation or the like, the electrode substrate made of a plastic film expands due to the above property, which causes a distortion of the display screen. It may appear, and display performance may be significantly reduced.
Such a problem is remarkable when one substrate is made of glass and the other substrate is made of a plastic film.

If the substrate is distorted for the above reason, the spherical spacers for securing the liquid crystal space are moved, and the spacers are locally uneven, resulting in irreversible display unevenness. Is.

[0008]

As described above, in a liquid crystal display device using a plastic film on one circuit board, when heat such as a backlight is applied during use, the substrate of the plastic film expands and a display screen is displayed. It has the problem of being distorted.

An object of the present invention is to provide a liquid crystal display device in which the display screen is not distorted in use.

[Constitution of Invention]

[0011]

A liquid crystal display device according to the present invention has first and second interdigital electrodes each having a plurality of electrode portions arranged in parallel on one surface of a transparent substrate. A heat-resistant film is used for at least one of these electrode substrates, and the first and second electrode substrates are opposed to each other in a predetermined positional relationship, and liquid crystal is sealed between these electrode substrates. In a liquid crystal display device in which these electrode substrates are sealed, fixed to each space portion between the plurality of electrode portions provided on any one of the electrode substrates and having a predetermined length along the electrode portion. The plurality of formed first spacers and the first spacers are arranged at different positions and substantially evenly distributed on the surface of the electrode substrate, and fixed to both the first and second electrode substrates. The second su It is obtained by a chromatography support.

[0012]

Here, one of the causes of the display unevenness in the large-sized liquid crystal display device is that the temperature of the display device rises due to the heat of the backlight or the like generated in the usage state. The heat-resistant film used as a substrate material of this type has a linear expansion coefficient of 1.5 to 2.0 times larger than that of glass which has been widely used as a substrate material. Further, it has the property of expanding when the humidity becomes high, and the humidity expansion coefficient shows a value close to the temperature expansion coefficient of glass. Since the thermal expansion coefficients differ greatly in this way, the generated heat causes the electrode substrate to bend.

The difference in expansion coefficient between such substrate materials is 2
Bending is likely to occur, for example, in the central portion apart from the portion where the electrode substrates are fixed. This deflection is proportional to the substrate size. When such a bending occurs, the spacers move, so that local unevenness of the spacers occurs and it appears as irreversible display unevenness. If the substrate is a heat resistant film, this bending makes it difficult to maintain a normal inter-substrate space.

Therefore, although the interdigital electrodes in which a plurality of electrode portions are arranged in parallel are formed in advance on the electrode substrate, between the plurality of electrode portions of one electrode substrate (the electrode portion is not formed). After the resin is hardened to form a plurality of first spacers in the space of the portion), the first spacers are formed.
Second spacers are formed between the spacers or in the space portion of the other electrode substrate, and at the time of assembly, these electrode substrates are opposed to each other in a predetermined relationship, and then the second spacer is cured to bond both electrode substrates. I am trying. As described above, since the spacer is directly provided on the electrode substrate and completely cured to be used as the spacer, it is possible to prevent non-reversible display unevenness due to movement of the spacer or the like. In addition, since the counter electrode substrate is adhered when the second spacer is cured, the flexure due to expansion is dispersed. Therefore, it is possible to eliminate the local deterioration of the display performance and the cause of the defect.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, 11 is a first electrode substrate, 12 is a second electrode substrate, and these first and second electrode substrates 1
The first and the second members 12 and 12 are opposed to each other by a first spacer 13 and a second spacer 14, which will be described later, with a predetermined space therebetween, and are opposed to each other in a predetermined arrangement relationship which will be described later. The liquid crystal 16 is filled in the gap formed between the first and second electrode substrates 11 and 12. Polarizing plates 17 and 18 are integrally provided on the outer surfaces of the first and second electrode substrates 11 and 12, respectively.

The first and second electrode substrates 11 and 12 are mainly composed of translucent substrates 21 and 22, and the material of the substrates 21 and 22 is the material for the second electrode substrate 12. Although glass is used for the substrate 22, the substrate 21 for the first electrode substrate 11 is used.
For this, a plastic film made of PET, PES, polyimide, or the like described above is used.

Next, a detailed structure of the electrode substrate 11 and a manufacturing method thereof will be described. On the surface of the substrate 21 (lower surface in the drawing),
A film-shaped electrode 24 is formed. As shown in FIG. 2, the electrode 24 has a so-called interdigital shape in which a plurality of electrode portions 25 are arranged in parallel with each other with a space portion 26 interposed therebetween.

Since the plastic film is used for the substrate 21 as described above, in forming the electrode, first, an ITO film is formed on the roll-shaped plastic film by sputtering to a thickness of 0.1 to 0.2 μm. To form a transparent conductive film. Next, this ITO
A photolithography method is applied to the film to continuously form the interdigital electrodes 24 parallel to the winding direction of the plastic film.

The first spacer 13 is made of an acrylic resin, an epoxy resin, a photosensitive polyimide resin or the like in the space portion 26 (between the parallel electrode portions 25) on the substrate 21 by using a printing method or photolithography. It is made of heat resistant material.

The height of the first spacer 13 is 2 to 7 μm and can be selected according to the set value of the cell gap as a liquid crystal cell. In addition, the first spacers 13 are arranged in the lateral direction in the figure along the plurality of interdigital electrode parts 25, and in order to secure a flow path of the liquid crystal composition, a length dimension of several pixels of the display device. To be cut out. Furthermore, the cross-sectional shape of the first spacer 13 is the space of the substrate 21.
It has a shape close to a trapezoid whose base is 26, and the shape of the end face cut out to secure the flow path of the liquid crystal composition is polygonal or semicircular as shown.

The first spacer 13 is provided in each space portion 26.
In order to maintain a predetermined interval that serves as a flow path for the liquid composition described above, a portion where the second spacer 14, which will be described later, is installed is left open in advance.
The installation locations of the second spacers 14 are set so as to be even with respect to the substrate surface.

In this way, the first spacers 13 are formed and completely cured, and then the alignment film 28 is applied to carry out the alignment treatment. It should be noted that a second spacer having the same shape as that of the first spacer 13 is provided at the second spacer installation location on the space 26.
The spacer 14 is formed by the same method.

Next, a detailed structure of the second electrode substrate 12 and a manufacturing method thereof will be described. The translucent substrate 22 of the second electrode substrate 12 is made of glass, for example. Similar to the first electrode substrate 13, as shown in FIG. 2, a comb-shaped electrode 24 in which a plurality of electrode portions 25 are arranged in parallel with a space portion 26 is formed on the substrate 22 by sputtering or sputtering. It is formed by the photolithography method. In addition, an alignment film 28 is applied on the interdigital electrode 24 to perform the alignment treatment.

This second electrode substrate 12 is different from the first electrode substrate 11 in the electrode portion 25 of each interdigital electrode 24.
Are arranged to face each other in a predetermined positional relationship orthogonal to each other. Then, with the first spacer 13 and the second spacer 14 maintaining a predetermined space, a sealing material 15
Then, the first and second electrode substrates 11 and 12 are integrally joined in the predetermined positional relationship. In this joining, the joining portion is pressure-welded and ultraviolet rays are radiated from the back surface to simultaneously cure the sealing portion coated with the sealing material 15 and the second spacer 14, and the first electrode substrate 11 and the second electrode substrate 11 The electrode substrate 12 and the electrode substrate 12 are integrally joined in the state where the distance is maintained.
That is, the second spacer 14 is hardened at the time of the above-mentioned joining, and adheres to both electrode substrates 11 and 12, respectively.

After bonding the first electrode substrate 11 and the second electrode substrate 12 in this manner, the liquid crystal 16 is injected into the space,
It constitutes a liquid crystal cell. The liquid crystal display device is constructed by connecting the electrodes 24 of the liquid crystal cell to control means (not shown).

Here, the first spacer 13 and the second spacer 13
The area occupied by the spacer 14 is preferably about 10% with respect to the opening. Further, the proportion occupied by the second spacer 14 is preferably 5% or less.

In the above structure, when used as a liquid crystal display device, heat is generated by a backlight or the like, and this heat is added to the liquid crystal cell formed by joining the first electrode substrate 11 and the second electrode substrate 12 together. A plastic film is used for the transparent substrate 21 of the first electrode substrate 11 of this liquid crystal cell, and glass is used for the transparent substrate 22 of the second electrode substrate 12, so When the heat is applied, the first electrode substrate 11 is bent due to the difference in linear expansion coefficient between the two. However, in the above configuration, since the spacer is directly provided on the electrode substrate 11 and is completely cured and used as the spacer, non-reversible display unevenness due to the movement of the spacer or the like does not occur unlike the conventional case. Further, since the counter electrode substrate, that is, the second electrode substrate 22 is adhered when the second spacer 14 is cured, the flexure due to expansion is dispersed.
Therefore, it is possible to eliminate the local deterioration of the display performance and the cause of the defect.

Next, another embodiment shown in FIG. 3 will be described.

This embodiment also has a first electrode substrate 11 and a second electrode substrate 12, which are kept at a predetermined distance by a first spacer 13 and a second spacer 14 and a sealing material 15. The liquid crystal 16 is bonded and sealed within this space.

Of these, the first electrode substrate 11 has basically the same structure as that described with reference to FIG. 1, and a plurality of electrode portions 25 are respectively provided on the substrate 21 made of a plastic film with a space portion 26 interposed therebetween. The interdigital electrodes 24 arranged in parallel are formed, the first spacer 13 is installed on the space portion 26, and the first spacer 13 is provided on the space portion 26 as shown in FIG. The second spacer 14 is formed at a position sandwiched by the spacers 13 and the alignment film 28 is further provided.

The second electrode substrate 12 is made of glass as the translucent substrate 22, and a plurality of signal electrodes 30 and image electrodes 31 for display pixels are formed on the upper surface thereof. ing. MIM (Metal Insulsto) is formed on each of the signal electrodes 30.
(r Metal) element 32 is connected and installed, and the signal electrode 30 is connected to the image electrode 31 via the MIM element 32. An alignment film is formed on the MIM element 32 and each image electrode 31.
33 are provided. The first electrode substrate 11 and the second electrode substrate 12 configured in this manner are joined together with a predetermined positional relationship and a predetermined gap maintained. That is, the first electrode substrate
After applying the sealing material 15 around 11 and aligning both electrode substrates 11 and 12, press them together and irradiate ultraviolet rays from the back side to bond and cure the sealing part, and then laser Light from the second electrode substrate 12 side to the first electrode substrate
The second spacer 14 on the first electrode 11 is irradiated with the first electrode substrate 11
And the second electrode substrate 12 are locally welded. Then, the liquid crystal 16 is injected into the space to form a liquid crystal cell.

With such a structure, as in the embodiment of FIG. 1, heat is applied during use as a liquid crystal display device, whereby the spacers move and the difference in the expansion coefficient of the substrate material becomes different from the conventional one. The display quality can be improved without causing display unevenness due to bending or the like. In addition, it is possible to obtain a secondary effect that the step of spraying the spacer, which is a dust source, can be omitted from the step of assembling the liquid crystal cell that dislikes foreign matters.

The first spacer 13 and the second spacer 14 may be made of the same resin, or may be made of two or more kinds of resins having different curing methods.

Further, the second spacer 14 is formed on the space portion 26 of the first electrode substrate 11 together with the first spacer 13, and both electrode substrates 11, 1 are bonded at the time of bonding with the second electrode substrate 12.
The second spacer has been described as being bonded to both sides.
It is also possible to form 14 on the second electrode substrate 12 and bond it to both of the electrode substrates 11 and 12 when the first electrode substrate 11 is bonded.

[0036]

As described above, according to the present invention, since the spacer is directly provided on the electrode substrate and completely cured to be used as the spacer, the spacer does not move. It is possible to obtain a liquid crystal display device having excellent display quality without causing screen distortion.

[Brief description of drawings]

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

FIG. 2 is a plan view showing a relationship between electrodes and spacers shown in FIG.

FIG. 3 is a sectional view showing another embodiment of the present invention.

[Explanation of symbols]

 11 First Electrode Substrate 12 Second Electrode Substrate 13 First Spacer 14 Second Spacer 16 Liquid Crystal 21,22 Translucent Substrate 24 Interdigital Electrode 25 Electrode 26 Space

Claims (1)

[Claims] 1. A first and a second electrode substrate having interdigital electrodes in which a plurality of electrode portions are arranged in parallel are provided on one surface of a translucent substrate, and at least one of these substrates is provided. A heat-resistant film is used as the material, and these first
And the second electrode substrate are opposed to each other in a predetermined positional relationship,
In a liquid crystal display device in which liquid crystal is sealed between the electrode substrates and between the electrode substrates, the liquid crystal display device is fixed to each space portion between the plurality of electrode portions provided on one of the electrode substrates, and A plurality of first spacers formed to have a predetermined length along the electrode portion, and the first spacers are arranged at positions different from the first spacers and substantially evenly distributed on the electrode substrate surface. Second
A second spacer fixed to both of the electrode substrates of 1., and a liquid crystal display device.