JPS6356625A - Liquid crystal device - Google Patents

Abstract

PURPOSE:To prevent electrons from malfunctioning and to improve the stability and durability of an element by making the outside surface of at least one transparent substrate conductive. CONSTITUTION:A display device 100 is constituted by sandwiching liquid crystal 2 between two transparent substrates 1a and 1b, and forming transparent conductive films 6a and 6b on the outside surfaces of the substrates 1a and 1b so as to make the surfaces conductive. Those transparent conductive films 6a and 6b discharge static electricity generated on the surfaces of the transparent substrates 1a and 1b and in dust in the outside air, etc. Consequently, the adverse influence of the static electricity upon the liquid crystal is reduced and the stability and durability of the element are improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a liquid crystal device, and particularly to a liquid crystal device whose substrate is surface-treated.

[Summary of the Disclosure] This specification and drawings disclose that in a liquid crystal device in which a liquid crystal is sandwiched between two substrates, the influence of static electricity is reduced by applying conductive treatment to the outer surface of at least one transparent substrate. The present invention discloses a technology that prevents malfunctions caused by the device and improves the stability and durability of the device.

[Background Art] In recent years, liquid crystals have made remarkable advances in the field of display devices. A typical example of this type of liquid crystal display device is shown in FIG. 3. In FIG. 3, a liquid crystal display device 10 includes a liquid crystal 2 sandwiched between two transparent substrates 1a and 1b, and A polarizing plate 3 is attached to the panel, and an electrode 4 and an alignment film 5 are formed on the inner side in contact with the liquid crystal 2. Conventionally, no treatment has been applied to the outer surface of the transparent substrate 1 or the outer surface of the polarizing plate 3. On the other hand, when trying to improve the purity of the liquid crystal 2, the electrical resistance increases. The electrical resistance of liquid crystals used in calculators, etc. is approximately IQIOΩ.
cm, but recently IQII~1QI2Ω
Liquid crystal materials having a resistance value of Cm are also commercially available and are actually used.

[Problems to be Solved by the Invention] When static electricity is applied from the outside to a liquid crystal display device as described above, the surface of the polarizing plate 3 or, if the polarizing plate 3 is not used, the surface of the transparent substrate l becomes charged. However, static charges gather on the surface of the polarizing plate 3 or the surface of the transparent substrate 1, and the lines of electric force penetrate the liquid crystal layer. Normally, a liquid crystal display device uses a nematic liquid crystal with positive dielectric anisotropy aligned horizontally on a substrate, so even if no electric field is applied between the pair of electrodes 4, this static electricity alone can cause the liquid crystal to flow. There was a problem with it not working.

This will be explained quantitatively with reference to FIG. FIG. 4 is an equivalent circuit diagram when a high impedance exists between the pair of electrodes 4. In FIG. 4, if the capacitance of the transparent substrate l is Cg, the capacitance of the alignment film 5 is G+, and the capacitance and resistance of the liquid crystal 2 are CtC and RLC, the voltage VtC applied to the liquid crystal is the static electricity applied to the transparent substrate l. For the voltage VST, the following equation is obtained.

However, here, it is assumed that 10 KV of static electricity is generated on the glass, the glass thickness is 1.1 am, its dielectric constant is 2.5, the alignment film thickness is 1000 A, its dielectric constant is 3, the liquid crystal layer thickness is 1107 p, and its dielectric constant is 10. In this case, a DC voltage of approximately 45 V will be applied to the liquid crystal portion, which will not only cause malfunction of the device but also have an adverse effect on performance. In addition, the electric field caused by static electricity disappears due to the resistance RLC in Figure 4, or in other words, due to the migration of positive and negative ions in the liquid crystal, and the liquid crystal returns to a state where there is no electric field. However, when the electrical resistance of the liquid crystal increases, this migration is caused Since the amount of ionic material that is present decreases, the electric field remains for a long time, and the liquid crystal continues to operate. Therefore, this static electricity is added to the drive signal, resulting in a malfunction.

The present invention has been made in view of these problems, and an object of the present invention is to provide a liquid crystal display device in which the adverse effects of static electricity on liquid crystals are reduced and the stability and durability of the elements are improved.

[Means for Solving the Problems] In the present invention, a device devised to solve the above problems has a liquid crystal sandwiched between two substrates, and at least one of the substrates is a transparent substrate. This is a liquid crystal display device characterized in that the outer surface of a transparent substrate or the surface of a polarizing plate attached to the outer surface is subjected to conductive treatment.

[Function] When not using a polarizing plate, conductive treatment is applied to the outside of the substrate glass, and when a polarizing plate is used, conductive treatment is applied to the surface of the polarizing plate to release static electricity.Their surface resistance is The resistance is suppressed to 107 ohms or less to prevent deterioration due to high level direct current application.

[Example] FIG. 1 is a longitudinal sectional view showing an example of the structure of a liquid crystal display device embodying the present invention. In FIG. 1, a liquid crystal display device 1
In 00, a liquid crystal 2 is sandwiched between two transparent substrates 1a and 1b, and transparent conductive films 6a and 6b are formed on the outer surfaces of the transparent substrates 1a and 1b as conductive treatment.
The transparent conductive films 6a and 6b release static electricity generated on the surfaces of the transparent substrates 1a and 1b and dust in the air outside thereof. In the figure, 4 is an electrode, 5 is an alignment film, 7 is a sealing material, and 8 is a conductive paste.

FIG. 2 is a longitudinal sectional view showing another example of the structure of a liquid crystal display device embodying the present invention. In the figure, a liquid crystal display device 101 has a liquid crystal 2 sandwiched between two transparent substrates 1a and 1b, and polarizing plates 3a and 3b are attached to the outer surfaces of the transparent substrates 1a and 1b. Transparent conductive films 6a and 6b are formed on the surfaces of 3a and 3b as conductive treatment. The transparent conductive films 6a and 6b release static electricity generated on the surfaces of the polarizing plates 3a and 3b and on dust in the air outside. Note that the transparent conductive film 6a.

If the formation of the polarizing plates 6b is performed before attaching the polarizing plates 3a and 3b to the substrate, it is very effective as a countermeasure against static electricity during the attaching operation.

Furthermore, in the embodiments shown in FIGS. 1 and 2, one of the substrates may not be a transparent substrate. In that case, the polarizing plate is normally provided only on the side of the transparent substrate, but it is desirable that the conductive treatment of the present invention be applied to the outside of both sides.

Furthermore, in the embodiments shown in FIGS. 1 and 2, the conductive treatment may be applied by spraying a surfactant, or by applying an inorganic antistatic agent having a hydroxyl group. But that's fine. However, the electrical resistance of one surface should be about 107 ohms or less.

[Effects of the Invention] As described above, according to the present invention, it is possible to obtain a liquid crystal display device in which the negative influence of static electricity on liquid crystal is reduced and the stability and durability of the element are improved. #: It is effective for liquid crystal elements having electrically floating electrodes, such as LCDs equipped with active elements such as TFTs and MIX.

[Brief explanation of the drawing]

FIG. 1 is a vertical cross-sectional view of an embodiment of the liquid crystal display device of the present invention;
FIG. 2 is a longitudinal sectional view of another embodiment of the present invention, FIG. 3 is a longitudinal sectional view of the structure of a conventional liquid crystal display device, and FIG. 4 is an equivalent circuit diagram between electrodes. la, lb: transparent substrate, 2: liquid crystal, 3.3a, 3
b: polarizing plate, 4: electrode, 5: alignment film, 6a, 6b: conductive treatment section.

Claims (6)

[Claims] (1) A liquid crystal device in which a liquid crystal is sandwiched between two substrates, and at least one of the substrates is a transparent substrate, wherein the outer surface of the transparent substrate is subjected to conductive treatment. Device. (2) The liquid crystal device according to claim 1, wherein a polarizing plate is attached to the outer surface of the transparent substrate, and the surface is subjected to conductive treatment. (3) The liquid crystal device according to claim 1 or 2, wherein the conductive treatment is a transparent conductive film. (4) The liquid crystal device according to claim 1 or 2, wherein the conductive treatment is performed using a surfactant. (5) The liquid crystal device according to claim 1 or 2, wherein the conductive treatment is performed using an inorganic material having a hydroxyl group on the surface. (6) The electrical resistance of the surface that has been subjected to conductive treatment is 1
The liquid crystal device according to any one of claims 1 to 5, characterized in that the resistance is 0^7 ohm or less.