JPH0437715A - Liquid crystal display device - Google Patents

Abstract

PURPOSE:To eliminate a display irregularity generated at he discharging path trace of the liquid crystal display device owing to electrostatic charging and discharging and to obtain the liquid crystal display device of high quality and high-definition by setting the volume resistivity of a substrate below a specific value. CONSTITUTION:In the liquid crystal display device 10, a transparent common electrode 13 and segment electrodes which are formed by vapor deposition or sputtering are adhered on the lamination-directionally internal surfaces of substrates 11 and 12 which are made of transparent glass or plastic. Resistance substrates whose volume resistivity is less than 10<9> OMEGAcm are used as the substrates 11 and 12. The manufacture of the resistance substrates 11 and 12 is performed by varying the composition rate in a transparent material such as glass and plastic and adding other materials. Thus, the volume resistivity of the substrates is set to <= 10<9> OMEGAcm at room temperature and then static electricity is prevented from being charged excessively.

Description

[Detailed description of the invention] Industrial applications The present invention relates to improvements in liquid crystal display devices.

Prior Art FIG. 2 is a sectional side view of a typical prior art liquid crystal display device. In the figure, 1 is a substrate made of glass or the like, 2 is a transparent electrode made of an ITO film of tin-added transparent electrode that is coated on the substrate 1 by vapor deposition, sputtering, etc., and 3 is a transparent electrode that is coated on the transparent electrode 2. 4 is a spacer, 5 is a liquid crystal, 6 is a sealing material, and 7 is a light control plate provided on the outer surface of the substrate 1. In the liquid crystal display device as described above, the polarizing plate 7 has a laminated structure of insulating films and has a tendency to be easily charged.For example, the polarizing plate 7 and the protective film f! It is well known that several hundred to several thousand volts of electrification is generated in the 11 release process.

During the manufacturing of liquid crystal display devices, there are many opportunities for static electricity to be generated, such as during the alignment process, the process for attaching the backlight plate, the process for peeling off the polarizing plate protective film, and the process for connecting the drive circuit.

Problems to be Solved by the Invention When the above-described polarizing plate 7 is charged with static electricity, charging is induced on the inner surface of the substrate 1 due to the electric double layer effect. The induced static electricity is accumulated without being discharged because the resistance of the substrate 1 is large. If this charging is excessive, the transparent substrate 2 will be charged, and the charges will remain accumulated between the opposing electrodes.

The static electricity charged inside the liquid crystal display device is discharged to the outside when the terminal portion comes into contact with metal. When this discharge occurs, the charged state of the orientation M3 and the spacer 4 located on the electrode that became the discharge path changes locally, and this works to locally vary the voltage of the liquid crystal 5. . Therefore, the traces of the discharge path are recognized as display unevenness corresponding to the transparent electrodes, resulting in a problem that the display quality of the liquid crystal display device is significantly deteriorated.

The present invention solves these problems and eliminates local electrostatic charging.
It is an object of the present invention to provide a liquid crystal display device that can avoid discharge and prevent display unevenness from occurring.

Means for Solving the Problems To achieve the above object, the present invention provides a liquid crystal display device in which transparent electrodes are formed on opposing surfaces of a pair of transparent substrates, and liquid crystal is sealed between these electrodes. , the liquid crystal display device is characterized in that the substrate has a volume resistivity of less than 109 Ωcm. 6 Functions Even if static electricity is generated on the surface of the liquid crystal display device, it is dispersed by the substrate having a low volume resistivity. By avoiding local charging and discharge teeth; preventing the occurrence of display unevenness on high display devices.

Embodiment FIG. 1 is a side sectional view showing a schematic configuration of an embodiment of a liquid crystal display device according to the present invention. As shown in FIG. 1, in the liquid crystal display device 10 of the present invention, substrates 11 and 12 made of transparent glass or plastic have transparent layers formed on their inner surfaces in the stacking direction by means such as vapor deposition or sputtering. Common electrode 13 and segment electrode 14 are deposited. Furthermore, each transparent electrode]
Alignment films 15 and 16 are formed so as to cover the entire inner surfaces of substrates 11 and 11 and 12 in the stacking direction, and an alignment process is performed. Between each substrate 11.12 is the electrode 13.14.
A single TN (Twisted Nematic) type liquid crystal, for example, is filled inside the spacer 17, which is separated by an alignment film 15, 16, and whose periphery is sealed with a sealant 18.Substrate 11, 12 Polarizing plates 20 and 21 are disposed on the outside in the stacking direction, respectively.

According to the invention, the substrate], 1. , 12, a low resistance substrate having a volume resistivity of 109 Ωcm or less is used. The production of the second resistive substrate 11, 12 is achieved by changing the composition ratio in a transparent material such as glass or phosphor, or by adding other substances.

Generally, the composition of soda lime glass is 5102-70~75
°19, entering a, ○-10~15%, Ca○7~8°6,
M g O-4-5%, A' l 20. It is produced by adding -1 to 2% and about 0.5% B2O3 to it, and 1
It has a volume resistivity of 0.9 Ωcm or more (at room temperature).

The low resistance substrate 11.12 according to the present invention has a volume resistivity of, for example, 10 at room temperature by increasing the mixing ratio of Na 203 or adding K ions to the above composition ratio.
It is set to be less than 9 Ωcm.

In addition, when a transparent plastic material such as polyester is used as the substrate 11, 12, a charge transfer material such as tetracyanoquinodimethane TCNQ or polysulfone nitride (SN2) is mixed into the transparent plastic.
Conductive particles such as metal particles and carbon particles '5 are mixed.

By setting the volume resistivity of the substrate to less than 10''Ωcm Kl at room temperature, excessive accumulation of static electricity is prevented.

As shown in 2, when the substrate 11.1.2 is a low-resistance substrate, the alignment treatment process (and rubbing treatment) for the crystal display device, the process of attaching the polarizing plate, and the process of protecting the polarizing plate. During the Funorum peeling process or the drive circuit connection process (:I), even if you rub your finger, cloth, etc. on the surface of the polarizing plate 20.21 and static electricity is generated, the charge will be dispersed on the substrate 11.12. , local excessive charging does not occur.Also, even if static electricity occurs as described in 1., the volume resistivity of the substrates 11 and 12 is small, so the charge is dissipated from the substrate surface to the outside air, and the charge is not generated on the substrate surface. Due to the accumulation of static electricity, the phenomenon of display unevenness in electrical path traces caused by discharge of accumulated static electricity, which occurs in the prior art, does not occur.

Regarding the lower limit of the resistivity of the low resistance substrate 11 at room temperature, a volume resistivity of 10'' to 105 Ωcm is considered to be electrostatic. Although there is no accumulation of static electricity since the discharge is carried out through the electrode, conductive leaks are likely to occur, so it is preferable to set the volume resistivity to 10 5 Ωcm or more.

The low resistivity substrate of the present invention is also effective when used as one of a pair of opposing substrates.

Further, in the low resistance substrate of the present invention, the shape of the transparent electrode does not have to be linear, but may have a configuration corresponding to the shape of the character to be displayed, and may have other shapes. .

Effects of the Invention As described above, the present invention reduces the volume resistivity of the substrate to 109 at room temperature.
Since it is less than Ωcm, display unevenness that occurs in the discharge path trace of the liquid crystal display device due to static electricity charging and discharging does not occur, and a high quality and high quality liquid crystal display device can be obtained.

[Brief explanation of drawings]

FIG. 1 is a simplified cross-sectional view of one embodiment of the present invention, and FIG. 2 is a simplified cross-sectional view of the prior art. 1112 Substrate, 13... Common electrode, 14 Segment electrode, 15.16 Alignment film, 17... Spacer, 18
・Sealing material, 19 ・Liquid crystal, 20.21 ・Polarizing plate agent Patent attorney Keiichiichi

Claims (1)

[Claims] In a liquid crystal display device in which transparent electrodes are formed on opposing surfaces of a pair of transparent substrates, and liquid crystal is sealed between these electrodes, the volume resistivity of the substrates is set to 10^9Ωc.
A liquid crystal display device characterized in that it is less than m.