JPH0368925A - Liquid crystal display device - Google Patents

Abstract

PURPOSE:To prevent the degradation in display grade by the electrification of spacers by setting the specific resistance on the surfaces of the spherical spacers between a pair of substrates at about the same level as the specific resistance of a liquid crystal. CONSTITUTION:The spacers 6 are formed by mixing carbon of about 0.01mum grain size at the time of reaction of the suspension polymn. of the crosslinked polymer of divinyl benzene. The specific resistance of the spacers is about 10<10>OMEGAcm with respect to 2X10<10>OMEGAcm specific resistance of the liquid crystal. The specific resistance of at least the surface thereof may be about the same level as the specific resistance of the liquid crystal. The transparent substrates 2a, 2b are sealed by a sealing member 5 and the liquid crystal 7 is packed therebetween. The specific resistance of at least the surface of the spacers is about the same level as the specific resistance of the liquid crystal and, therefore, static electricity generated at the time of applying a driving voltage to this liquid crystal display device disperses uniformly without being electrified on the spacers alone and is discharged through the electrodes. The drop of the threshold voltage by the liquid crystal around the spacers is, therefore, prevented and the degradation in the display grade is prevented.

Description

[Detailed description of the invention] Industrial applications The present invention relates to a liquid crystal display device.

Conventional technology FIG. 3 is a typical prior art cross-sectional view.

Transparent electrodes 3a, 3b are formed in a matrix on the opposing surfaces of the pair of transparent substrates 2a, 2b.
Orientations M4a and M4b are formed by covering M4a and M4b.

A spacer 6 is interposed between the pair of light-transmitting substrates to keep the cell thickness constant. Glass fiber is used as the material for the spacer 6.

However, as liquid crystal display devices become larger, highly accurate cell thickness uniformity is required, and large dot matrix liquid crystal display devices such as super twisted nematic type and 2N type super twisted nematic type , spacers that are plastic beads are used.

This spacer is a sphere with a particle size of 6 to 10 μm and a particle size accuracy of about 3σ=0.35 μm. In order to obtain a uniform cell thickness, 5 to 20 spacers are dispersed per pixel with a width of about 3 mm.

Divinylbenzene crosslinked polymers and benzoguanamine-formaldehyde condensation monomers are currently widely used as spacer materials.

Transparent substrates 2a and 2b are sealed with a seal member 5 and filled with liquid crystal 7. Polarizing plates 1a and lb are disposed on the outer surfaces of the transparent substrates 2a and 2b.

Problems to be Solved by the Invention In this prior art, the spacer 6 is made of an organic compound and has a high specific resistance, so it is easily charged by static electricity.

For example, static electricity is generated when the protective films of the polarizing plates 1a and lb disposed on the outer surfaces of the transparent substrates 2a and 2b are peeled off. This static electricity is discharged through conductors such as metals and human hands.

At this time, the spacer located in the static electricity discharge path is charged with static electricity without being discharged.

Since the spacer is charged in this way, when a driving voltage is applied to the liquid crystal display device, the electric field around the spacer changes and the threshold voltage of the liquid crystal around the spacer decreases. Therefore, the liquid crystal around the spacer is driven at a lower voltage than other liquid crystals.

As a result, a problem arises in that display quality is degraded in the liquid crystal around the spacer located in the electrostatic discharge path.

An object of the present invention is to provide a liquid crystal display device that prevents deterioration in display quality due to charging of spacers.

Means for Solving the Problems The present invention provides a liquid crystal display device in which a plurality of granular spacers are interposed between a pair of substrates to form a space, and this space is filled with liquid crystal. This is a liquid crystal display device characterized in that the specific resistance of the surface is approximately the same as that of the liquid crystal.

Function According to the present invention, the specific resistance of at least the surface of the spacer and the specific resistance of the liquid crystal are approximately the same. Therefore, the generated static electricity does not charge only the spacer, but is dispersed in a negative manner.The dispersed static electricity is discharged through the electrodes and the like. This prevents the threshold voltage from decreasing in the liquid crystal around the spacer as in the conventional case.

Example FIG. 1 is a sectional view of one embodiment of the present invention.

In this liquid crystal display device, transparent electrodes 3a, 3b are formed in a matrix on the opposing surfaces of a pair of transparent substrates 2a, 2b, and alignment films 4a, 3b are formed by covering the transparent electrodes 3a, 3b.
b is formed.

A spacer 6 is interposed between the pair of light-transmitting substrates to keep the cell thickness constant. This spacer 6 is made by mixing a conductor into the material of the spacer 6 during manufacture so that its resistivity is approximately the same as that of the liquid crystal. First, a spherical spacer is produced by mixing carbon with an organic compound such as a divinylbenzene crosslinked heavy body or a benzoguanamine-formaldehyde condensate. For example, during suspension polymerization of divinylbenzene crosslinked polymer, a few percent of the particle size is 0.
．． It is manufactured by mixing carbon with a diameter of about 0.01 μm. While the specific resistance of the liquid crystal filled in the liquid crystal display device is 2×101oΩcm, the specific resistance of this spacer is 101oΩc.
It is about m. In this way, in addition to a spacer having a similar resistivity to the inside, a spacer may be used in which the resistivity at least on the surface is approximately the same as that of the liquid crystal.

The transparent substrates 2a and 2b are sealed with a sealing member 5 and the liquid crystal 7
is filled. Polarizing plates 1a and lb are disposed on the outer surfaces of the transparent substrates 2a and 2b.

Static electricity was applied to the thus produced liquid crystal display device according to an embodiment of the present invention and a typical prior art liquid crystal display device using a static electricity generator, and the display quality was compared. The results are shown in Table 1.

Table 1 In Table 1, cases in which no deterioration in display quality was observed are indicated by a reference mark O, and cases in which a deterioration in display quality was observed are indicated by a reference mark x.

As shown in Table 1, in typical prior art liquid crystal display devices, the specific resistance of the spacer is large, so when a voltage of 300 V is applied, the display quality is already affected by the liquid crystal around the spacer, which is located in the electrostatic discharge path. Deterioration was detected. On the other hand, in the liquid crystal display device of one example of the present invention, since the specific resistance of the spacer and the specific resistance of the liquid crystal were approximately the same, no deterioration in display quality occurred even when 10 kV of static electricity was applied.

2 and 4 are diagrams created based on 100x am mirror photographs showing the display state of the liquid crystal display device when the electrostatic applied voltage is 5 kV. FIG. 4 is a diagram showing the display quality of the liquid crystal display device of the prior art.

In FIGS. 2 and 4, the spacer is indicated by reference numeral 6, and the electrostatic charge applying section is indicated by reference numeral A. As shown in FIG. 4, in the prior art liquid crystal display device, the spacer is charged and the electric field around the spacer is changes and lowers the threshold voltage of the liquid crystal around the spacer, resulting in a reduction in display quality along the electrostatic discharge path. On the other hand, as shown in FIG. 2, in the liquid crystal display device of the present invention, the display quality is significantly improved.

Effects of the Invention As described above, according to the present invention, since the specific resistance of the spacer is approximately the same as the specific resistance of the liquid crystal, the spacer is prevented from being charged with static electricity. Therefore, the threshold voltage of the liquid crystal around the spacer is prevented from dropping, and display quality is prevented from deteriorating.

[Brief explanation of drawings]

Figure 1 is a sectional view of an embodiment of the present invention, Figure 2 is a diagram showing display quality of an embodiment of the present invention, Figure 3 is a sectional view of the prior art, and Figure 4 is the display quality of the prior art. FIG. la, lb...polarizing plate, 2a, 2b...transparent substrate.

Claims (1)

[Scope of Claims] A liquid crystal display device configured by interposing a plurality of granular spacers to form a space between a pair of substrates, and filling this space with liquid crystal, wherein the specific resistance of at least the surface of the spacer is A liquid crystal display device characterized by having a resistivity that is approximately the same as that of a liquid crystal.