JPS6157926A - Liquid crystal display element - Google Patents

Abstract

PURPOSE:To enlarge drivable voltage width in a liquid crystal display element that makes display utilizing nematic-cholesteric phase transition by forming thin polypyrrole films by electrochemical oxidative polymerization on glass substrates in which transparent electrodes are formed. CONSTITUTION:Transparent electrodes 2a and 2b are provided on the inner side of two opposing glass substrates 1a and 1b. Thin polypyrrole films 3a and 3b are formed as orientation films on the glass substrates 1a and 1b in which transparent electrodes 2a and 2b are formed. When voltage is applied to a display element manufactured by using the orientation film, liquid crystal and glass substrate, its drivable voltage width is about 5.0V. This is larger than conventional voltage widths, about 2.0V, by about 3.0V.

Description

DETAILED DESCRIPTION OF THE INVENTION Industrial Applicability The present invention relates to a nematic-cholesteric phase change type crystal display element, and more particularly to a liquid crystal display element that exhibits high contrast and stable operation.

2. Description of the Related Art A liquid crystal display device is known in which transparent electrodes are formed on the inner walls of opposing glass substrates, and a nematic-cholesteric mixed liquid crystal is hermetically sealed in the gap between the substrates. The change in transmittance versus voltage of a nematic-cholesteric phase transition type liquid crystal display element shows a hysteresis loop as shown in Figure 3. In this figure, there are voltages (Vo) at which light transmission blockage greatly differs at the same voltage. , there is a method of displaying the melancholy part and the background part using such a voltage vo. This type of display method uses electric field effects, so there are variations in the size of the energy knobs, as shown in Figure 3.The tiger hysteresis loop maintains the same shape and moves to the higher voltage side, and at the same time moves to the lower voltage side. I will have to move. The panel gap is influenced by the alignment film.

In order to produce a desired molecular alignment on the glass substrate on which the transparent electrode is formed, an alignment film for the liquid crystal display panel is formed to prevent deterioration during use of the panel. Refuga,
The alignment film has conventionally been made of organic polymers such as polyimide, polyvinyl alcohol, etc.

Inorganic substances such as WO2, coupling agents such as silane force/twisting agents, nathanate coupling agents, etc. are known. However, these oriented films are difficult to form due to their formation method, namely spin-coding method.

In vacuum evaporation, etc., irregularities occur on the surface of the film.

Problems to be Solved by the Invention In the present invention, due to the unevenness of the surface of the alignment film in the liquid crystal display element, the hysteresis loop has a large difference in light transmission blockage at the same voltage. This solves the problem of poor display contrast and difficulty in viewing when manufacturing a display element with a size of about A5 size.

Means for Solving the Problems According to the present invention, the above-mentioned problems are solved by a liquid crystal display element that displays by utilizing nematic co-cholesteric phase transition by interposing a liquid crystal between opposing glass substrates on which transparent electrodes are formed. The problem is solved by a liquid crystal display panel characterized in that a polypyrrole thin film is formed by electrochemical oxidative polymerization on a glass substrate on which the transparent electrode is formed.

Function: Since the polypyrrole thin film described above is formed by electrochemical oxidation, its thickness and surface condition are maintained uniform.

Example Embodiments of the present invention will be described below based on the drawings.

FIG. 1 is a schematic cross-sectional view for explaining a liquid crystal display element according to the present invention.

As shown in FIG. 1, transparent electrodes 2a and 2b are provided on the inner surfaces of two opposing glass substrates 1a and 1b, and the transparent electrodes 2a and 2b are formed on the glass substrate 1a.
and polypyrrole thin films 3a and 3 as alignment films on 1b.
b is formed.

In this figure, 4 and 5 indicate a liquid crystal and a spacer, respectively.

below! A method for manufacturing an alignment film for the display element will be described with reference to FIG.

As shown in FIG.
Prepare the π acetonitrile solution 8 and add the glass group 1fi (I
TO substrate) Using the transparent electrode 2a formed on Ia and the platinum electrode 7 as both electrodes, gas decomposition was performed at 1.0 volts using a battery 9, and electrochemical oxidation polymerization was performed for 30 minutes to form a polypyrrole thin film as shown in Fig. 1. Form as shown. The thickness of the thin film is preferably 1000 to 2000, and the transparent electrode 2a is made to cover the glass substrate.

The liquid crystal according to the present invention is Nr2 as a nematic liquid crystal.
A netic-cholesteric phase change shielding crystal was prepared by mixing 90% by weight of N.801 and 10% by weight of CB-15 as a cholesteric liquid crystal.

When a voltage was applied to a display element (Fig. 1) manufactured using the above-mentioned alignment film, crystal, and glass substrate, and a light transmission voltage curve was obtained, the voltage width that could be driven was approximately 5.Ov.
It happened.

FIG. 3 is a diagram showing a light transmission couple voltage curve (hysteresis loop), in which ■-■ indicates the voltage range that can be driven.

In order to compare with the example of the present invention, a nematic-cholesteric phase change type liquid crystal display element was manufactured in the same manner as in the example except that a polyimide film was formed as an alignment film on an ITO substrate using a spin cord V. . As a result, the voltage width that can be driven to 1 is about 2. Ov, about 3.0% compared to the example. It was small.

DETAILED DESCRIPTION OF THE INVENTION As described in L7, the nematic-cholesteric phase change display element using a polypyrrole thin film as an alignment film can be driven over a wide voltage range, making it possible to achieve stable multi-mode display only with high contrast. .

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view for explaining a tube crystal display hexagon according to the present invention. Figure 2 (1) is a diagram showing a method for manufacturing the alignment film of the display element in Figure 1, and Figure 3 is a light transmission couple voltage curve diagram, which is used to disguise the voltage range that can be operated at 91%. 1a, 1b...Glass substrates, 2a, 2b...
...Transparent〒1wL, 3...Polypyrrole thin film (alignment film), 4...Liquid crystal, 5...
...Spacer, 6...Container, 7...
...Silver t! Fi? , EL=...Acetonitrile solution of polypyrrole, 9...Battery. Margin below

Claims (1)

[Scope of Claims] 1. In a liquid crystal display element that displays using nematic-cholesteric phase transition by interposing a liquid crystal between opposing glass substrates on which transparent electrodes are formed, the liquid crystal display element comprises: 1. A liquid crystal display element comprising a polypyrrole thin film formed by electrochemical oxidative polymerization.