JPH04177320A - Liquid crystal device - Google Patents

Abstract

PURPOSE:To provide one liquid crystal device with both of high contrast characteristic and high speed response by making the component of liquid crystals sandwiched between two pairs of transparent substrates different for each, and by switching a panel driven when necessary. CONSTITUTION:The arranged film layers of substrates 11a-11d are opposed with each other, and liquid crystal particles 14 and 15 form spiral structures 16, 17 which are twisted by not less than 180 deg., while liquid crystal driving voltage can be applied to transparent electrodes 12a-12d. A light source 18, a deflector 19a, and an analyser 19b are sealings 1a-1d for sealing the liquid crystal particles. The components of the liquid crystals 14, 15 sandwiched between two pairs of transparent substrates 12a, 12b, and 12c, 12d, are different from each other, and a panel driven is switched when necessary. One liquid crystal device can thus be provided with both of high contrast characteristic and high speed response.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electro-optical device using liquid crystal used in systems such as computer terminals, image display devices, and shutters.

[Summary of the invention]

The present invention relates to a liquid crystal device, and more specifically, nematic liquid crystals having positive dielectric constant anisotropy with different twist directions are placed between two pairs of transparent substrates each having a transparent electrode and an alignment film on their surfaces. In a liquid crystal device comprising a pair of polarizing plates on the outside of the transparent substrates, which are sandwiched to form a helical structure twisted by more than 100 degrees, high contrast can be achieved by sandwiching liquid crystals of different components between the transparent substrates. A liquid crystal device characterized in that a type and a high-speed response type can be used separately.

[Conventional technology]

As a dot matrix type display device, liquid crystal display devices are attracting attention because they are thin, lightweight, and have low power consumption.

A conventional twisted nematic type liquid crystal display device has a helical structure in which the liquid crystal molecular layer is twisted at 90 degrees. In recent years, in order to sharpen the rise characteristics of liquid crystal molecules in response to changes in applied voltage, S T N (Super Twi
A sted nematic type liquid crystal display device has been devised and has been put into practical use as a large-capacity, high-contrast liquid crystal display device.

However, since the STM type liquid crystal display device utilizes the birefringence effect of liquid crystal, it has the disadvantage that the screen is colored with a characteristic yellow or dark blue color. Therefore, the 2N system, which uses two liquid crystal panels, was devised as an optical color compensation method to realize a black and white display with high visibility. This two-layer method is
Between a pair of polarizing plates, there is a driving STN panel for displaying and a compensation STN panel for eliminating coloration.
High-quality black-and-white display can be obtained by satisfying the following conditions: different heaving directions; (1) liquid crystal molecular axes of the overlapping portions intersect at right angles;

[IB to be Solved by the Invention] Even in such a two-layer STN type liquid crystal device, it is the driving STN panel that determines the optical characteristics. In other words, in order to obtain high contrast, a liquid crystal material with a steep rise characteristic with respect to the applied voltage is required, and in order to obtain high-speed response, a liquid crystal material with a thin cell thickness and a low viscosity and fast response speed is required. However, good radicalness and fast response speed are generally in a contradictory relationship, and there is currently no liquid crystal material that has both of these properties.

Therefore, if you use a liquid crystal material with a response speed that is compatible with a mouse when using it as a display screen for a personal computer, the contrast will be low enough to be used as a Japanese word processor.On the other hand, if you use a liquid crystal material with high contrast, The problem was that it couldn't keep up with the mouse's reactions.

[Means to solve the problem]

In order to solve the above problem, the present invention forms a helical structure twisted by 180 degrees or more in different positive directions between two pairs of transparent substrates each having a transparent electrode and an alignment film on their surfaces. In a liquid crystal device which is sandwiched as shown in FIG.
This allows the panel to be driven to be switched depending on the need.

〔Example〕

The details of the present invention will be explained below based on illustrated embodiments.

FIG. 1 shows a liquid crystal device according to the present invention, with reference numerals 11a and l in the figure.
lb, Ilc, and Ild are transparent substrates made of glass, plastic, etc. for sandwiching liquid crystal molecules, and transparent electrode layers 12a, 12b, 12C112d are formed on the surface, and a thin film of polyimide, Teflon, etc. Uniaxial alignment film layers 13a, 13b, and 13C113d are formed and rubbed in one direction. The alignment film layers of the substrates 11a and Ilb and IIC and lid face each other, and the liquid crystal molecules 14 and 15 are 18
It has a helical structure 16,17 twisted at an angle of 0° or more. Transparent electrode layers 12a, 12b and 12c, 1
A liquid crystal driving voltage can be applied to each of 2d. 18 is a light source, 19a is a polarizer, and 19b is an analyzer. ]a, 1b, lc, and Id are sealings for sealing liquid crystal molecules.

Here, specific examples and measurement results of the liquid crystal device according to the present invention will be described.

FIG. 2 is a diagram showing the optical axis directions in the liquid crystal device shown in FIG.
4 is the alignment direction of the substrate 11c, 25 is the alignment direction of the substrate 11d, and 26 is the lower polarizing plate transmission axis direction. 27 is the angle from the upper polarizing plate yj pass wheel axis direction to the orientation direction of the substrate 11b (hereinafter abbreviated as "A"), 28 is the angle from the lower polarizing plate transmission axis direction to the orientation direction of the substrate lid (hereinafter abbreviated as rBJ) It is. The direction of the angle was ``ten'' clockwise.

Here, an example of a negative mode is shown in which the black level of the displayed color decreases (light-shielding property decreases) as the applied voltage value increases.

The twist angle of both LCD panels used was 260”.
, Δnd=0.88. C1m, one cell thickness is 6.
5 μm and the other was 4.5 μm.

The twist directions are clockwise and counterclockwise, respectively.

"A" = ~50°, CB] = -50°.

Table 1 shows the optical characteristics of the liquid crystal device according to the present invention.
0Duty 1/15. These are the contrast and response speed when multiplex driving voltage of IBias is applied.

Table 1 Optical characteristics of the liquid crystal device of the present invention As shown in Table 1, by switching the liquid crystal panel to be driven, one liquid crystal device can have both high contrast and high speed response characteristics.

(Effects of the Invention) As explained above, according to the present invention, two pairs of transparent substrates each having a transparent electrode and an alignment film on their surfaces have positive dielectric constant anisotropy with different twist directions. In a liquid crystal device in which a nematic liquid crystal is sandwiched so as to form a twisted or twisted structure of 180° or more in the thickness direction, and a pair of polarizing plates is provided on the outside of the transparent substrate, the nematic liquid crystal is sandwiched between the two pairs of transparent substrates. By making the components of the liquid crystals different and switching the driving panel as necessary, a single liquid crystal device can have both high contrast and high-speed response characteristics.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a liquid crystal device of the present invention, and FIG. 2 is a diagram showing the optical axis direction of the liquid crystal device of the present invention. 11a, llb, llc, lid・=i! Bright substrate substrate 1
2a, 12b 2 C, 12d-! Bright electrode layer 13a, 1
3b, 13c, 13d ---Alignment film 14.15...
・・・・・・・・・Liquid crystal molecules 16.17・・・・・・
....Spiral structure 18 .....Light source 19a ......Polarizer 19b ...
・・・・・・・・・Analyzer la, Ib, 1c, ]d
...Sealing for encapsulating liquid crystal molecules and above Applicant: Seiko Electronic Industries Co., Ltd. Representative Patent Attorney: Keisuke Hayashi Figure 1

Claims (1)

[Claims] Between two pairs of transparent substrates with transparent electrodes and alignment films on their surfaces,
Nematic liquid crystals having positive dielectric constant anisotropy with different twist directions are sandwiched so as to form a helical structure twisted by 180° or more in the thickness direction, and a pair of polarizing plates is provided on the outside of the transparent substrate. 1. A liquid crystal device comprising: a liquid crystal device sandwiched between the transparent substrates, which has different components so that it can be switched between a high-contrast type and a high-speed response type.