JPH0990391A - Liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obviate the occurrence of the abnormality in orientation. SOLUTION: Tacky adhesive layers 20, 21 for sticking polarizing plates 22, 23 to the outside surfaces of film substrates 11, 12 consist of tacky adhesives formed by incorporating conductive particles into tacky adhesives and are, therefore, usable as conductive layers for grounding. If both of these tacky adhesive layers 20, 21 are, thereupon, held connected to the grounding potential, the charges by static electricity is allowed to escape via the tacky adhesive layers 20, 21 in spite of the generation of the static electricity in either of the two film substrates 11, 12 and, therefore, the generation of a potential difference between the two film substrates 11, 12 does not arise and eventually, the occurrence of the abnormality in the orientation is obviated.

Description

Detailed Description of the Invention

[0001]

[0001] The present invention relates to a liquid crystal display device.

[0002]

2. Description of the Related Art A liquid crystal display device has a structure in which two film substrates having transparent electrodes provided on opposite surfaces thereof are bonded to each other via a sealing material and liquid crystal is sealed between them. FIG. 5 shows a part of a film substrate which is a base of the film substrate in such a conventional liquid crystal display device. This film substrate is made of polyether sulfone,
The base film 1 is made of a transparent resin film of polyarylate, polycarbonate, polyethylene terephthalate or the like. A bonding film 2 made of acrylic resin is provided on the lower surface of the base film 1 by a method such as coating, and a transparent conductive film 3 made of ITO is provided on the lower surface of the bonding film 2 by a method such as vapor deposition or sputtering.
In this case, the bonding film 2 is for improving the adhesion between the base film 1 and the transparent conductive film 3. Then, when the transparent conductive film 3 is patterned, a transparent electrode having a predetermined pattern is formed.

[0003]

By the way, in such a conventional liquid crystal display device, when static electricity is generated on one of the film substrates due to friction or impact, the coupling film of the one film substrate is charged with static electricity. It will be. Then, in the part where the transparent electrode of one of the film substrates exists, the charge charged in the coupling film escapes through the transparent electrode,
In the portion where the transparent electrode does not exist, the electric charge charged in the binding film remains as it is. As a result, a potential difference is generated between one film substrate and the other film substrate in the portion where the electric charge charged in the binding film of the one film substrate remains, and liquid crystal molecules are generated in the portion where this potential difference occurs. There was a problem that an abnormal orientation (domain) would occur due to rising. An object of the present invention is to prevent alignment abnormalities from occurring.

[0004]

According to the present invention, in a liquid crystal display device in which liquid crystal is sealed between two film substrates, a conductive layer for grounding is provided on both front and back sides of the liquid crystal.

According to the present invention, when the grounding conductive layers provided on both front and back surfaces of the liquid crystal are both connected to the ground potential, even if static electricity occurs on one of the two film substrates. The electric charges due to the static electricity can be released through the grounding conductive layer, so that a potential difference does not occur between the two film substrates, and thus an abnormal alignment can be prevented.

[0006]

FIG. 1 shows a main part of a liquid crystal display device according to an embodiment of the present invention. This liquid crystal display device includes two film substrates 11 and 12. Transparent electrodes 13 and 14 and alignment films 15 and 16 are provided on the surfaces of the film substrates 11 and 12 which face each other. Both film substrates 11 and 12 are bonded together via a sealing material 17, and a liquid crystal 18 is sealed between both film substrates 11 and 12 inside the sealing material 17. In addition, the alignment film 1 of both film substrates 11 and 12
A spacer 19 is interposed between 5 and 16. Polarizing plates 22 and 23 are attached to the outer surfaces of both film substrates 11 and 12 via adhesive layers 20 and 21, respectively. In this case, although not shown in detail, the pressure-sensitive adhesive layers 20 and 21 are made of a conductive material having a transparent conductive film made of ITO or the like provided on the surface of transparent particles made of silicon oxide or the like by a method such as vapor deposition. It consists of a mixture of particles in an appropriate amount in a transparent adhesive. However, the particle size of the conductive particles depends on the pressure-sensitive adhesive layer 2
It is smaller than the thickness of 0 and 21.

As described above, in this liquid crystal display device, as the adhesive layers 20 and 21 for attaching the polarizing plates 22 and 23 to the outer surfaces of the film substrates 11 and 12, conductive particles are mixed in the adhesive. Since these are used, these pressure-sensitive adhesive layers 20 and 21 can be used as conductive layers. Therefore, if both the pressure-sensitive adhesive layers 20 and 21 are connected to the ground potential, even if static electricity is generated in either one of the two film substrates 11 and 12, the charge due to this static electricity is generated in the pressure-sensitive adhesive layers 20 and 21. Therefore, it is possible to prevent the potential difference between the two film substrates 11 and 12 and to prevent the alignment abnormality from occurring. As the conductive particles, transparent particles made of ITO or the like are provided on the surface of transparent particles made of silicon oxide, that is, transparent particles are used.
There is no problem on the display.

Here, FIG. 2 shows a part of the film substrate 31, which is the source of the film substrates 11 and 12.
The film substrate 31 includes a base film 32 made of a resin film similar to the conventional case. On the lower surface of the base film 32, a bonding film 3 made of acrylic resin is formed.
3 is provided by a method such as coating, and a transparent conductive film 34 made of ITO is provided on the lower surface of the coupling film 33 by a method such as vapor deposition or sputtering. Also in this case, the bonding film 33 is for improving the adhesion between the base film 32 and the transparent conductive film 34. Base film 3
A gas barrier layer 35 made of polyvinyl alcohol is provided on the upper surface of 2 by a method such as coating in order to prevent the permeation of oxygen from the outside. Gas barrier layer 35
In order to protect the gas barrier layer 35, a protective film 36 made of epoxy resin is provided on the upper surface of the substrate by a method such as coating. Then, when the transparent conductive film 34 is patterned, the transparent electrodes 13 and 14 having a predetermined pattern shown in FIG. 1 are formed.

Next, FIG. 3 shows a main part of a liquid crystal display device according to another embodiment of the present invention. In this liquid crystal display device, the film substrate 11 and the polarizing plate 22 on the front surface side
And a phase difference plate 41 is provided between the two. In this case, the pressure-sensitive adhesive layer 42 for sticking the retardation plate 41 to the outer surface of the film substrate 11 is made of a mixture of a suitable amount of transparent conductive particles in a transparent pressure-sensitive adhesive as in the case of the above embodiment. However, the pressure-sensitive adhesive layer 20 for sticking the polarizing plate 22 to the outer surface of the retardation plate 41 is made of only a normal transparent pressure-sensitive adhesive.

In the above embodiment, the case where the pressure-sensitive adhesive layer for sticking the polarizing plate or the retardation plate on the outer surface side of the film substrate is the conductive layer for grounding has been described, but the present invention is not limited to this. Absent. For example, the base film 32 shown in FIG. 2 may contain the conductive particles as described above. In this case, since the bonding film 33 made of acrylic resin provided on the lower surface of the base film 32 functions as an insulating film, there is no problem even if the base film 32 is used as the grounding conductive layer. Also, the base film 3
Instead of 2, the polarizing plate or the retardation plate may be used as the grounding conductive layer.

Next, FIG. 4 shows a main part of a liquid crystal display device according to still another embodiment of the present invention. In this liquid crystal display device, the transparent conductive layers 51 and 52 made of ITO and having a film thickness of about 500 to 1000 Å are formed on the outer surfaces of the film substrates 11 and 12 composed of the base film 32 and the coupling film 33 shown in FIG. Provided by the method. In this case, the transparent conductive layers 51, 52 have a function as a gas barrier layer that blocks permeation of oxygen from the outside, in addition to the function as a grounding conductive layer. Note that such a transparent conductive layer may be provided not on the outer surface of the film substrate but on the inner surface or the outer surface of the polarizing plate or the retardation plate.

[0012]

As described above, according to the present invention, if the grounding conductive layers provided on both front and back sides of the liquid crystal are both connected to the ground potential, either of the two film substrates will be formed. Even if static electricity is generated on one side, the electric charge due to this static electricity can be released through the grounding conductive layer, so that no potential difference is generated between the two film substrates, and thus an abnormal alignment is prevented. can do.

[Brief description of drawings]

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

FIG. 2 is a perspective view showing a part of a film substrate which is a source of the film substrate shown in FIG.

FIG. 3 is a sectional view showing a main part of a liquid crystal display device according to another embodiment of the present invention.

FIG. 4 is a sectional view showing a main part of a liquid crystal display device according to still another embodiment of the present invention.

FIG. 5 is a perspective view showing a part of a film substrate which is a base of a conventional film substrate.

[Explanation of symbols]

 11, 12 Film substrate 18 Liquid crystal 20, 21 Adhesive layer 22, 23 Polarizing plate

Claims (7)

[Claims] 1. A liquid crystal display device in which a liquid crystal is sealed between two film substrates, wherein a grounding conductive layer is provided on each of the front and back sides of the liquid crystal. 2. The invention according to claim 1, wherein the grounding conductive layer is an adhesive layer for attaching a polarizing plate or a retardation plate to the outer surface side of the film substrate, and the adhesive layer is an adhesive. A liquid crystal display device characterized by comprising conductive particles mixed therein. 3. The invention according to claim 1, wherein the grounding conductive layer comprises the film substrate, and the film substrate comprises an insulating film provided on the inner surface of a base film containing conductive particles. Characteristic liquid crystal display device. 4. The invention according to claim 1, wherein the grounding conductive layer comprises a polarizing plate or a retardation plate attached to the outer surface side of the film substrate, and the polarizing plate or the retardation plate contains conductive particles. A liquid crystal display device, characterized in that it is comprised. 5. The liquid crystal display device according to any one of claims 2 to 4, wherein the conductive particles are transparent. 6. The invention according to claim 5, wherein the conductive particles are ITO on the surface of transparent particles made of silicon oxide or the like.
A liquid crystal display device comprising a transparent conductive film made of, for example. 7. The IT according to claim 1, wherein the grounding conductive layer is provided on the outer surface side of the film substrate.
A liquid crystal display device comprising a transparent conductive layer made of O or the like.