JPH01147431A - Display device - Google Patents

Abstract

PURPOSE:To obtain a lightweight and high-capacity display device of a black and white display with a high contrast at a low cost by disposing a film or sheet consisting of chitin or chitosan in parallel with a liquid crystal cell for display. CONSTITUTION:A phase plate 3 of the film or sheet consisting of the chitin or chitosan is used as an optical compensator. The incident light past a polarizer 1 is made to linearly polarized light. This light is made to elliptically or circularly polarized light by a double refraction effect when the light passes the liquid crystal cell 2 for display. Furthermore, the light is made to the linearly polarized light in the same polarization direction as the polarization direction right after passage through the polarizer 1 when the light passes the phase plate 3. This linearly polarized light cannot pass an analyzer 4 and a black display is obtd. as the display. The liquid crystal cell 2 for display does not exhibit the double refraction effect when a signal voltage is impressed thereto; therefore, the light passes the cell in the state of the linearly polarized light and is made into the linearly polarized light changed in the axis of polarization by 90 deg. from the initial axis of the polarization by the phase plate 3 and the analyzer 4. The white display is thus obtd. as the display. The display device of the high contrast and low cost is thereby obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a display device using a chitin or chitosan film or sheet as an achromatic optical compensator in an SBE cell or an STN cell.

[Conventional technology]

As a display device, liquid crystals start from the dynamic scattering mode and T
Devices using the N effect have features such as low power consumption, and have been widely used in watches, TVs, etc. However, the T)i effect type liquid crystal display device has the disadvantage that when the number of scanning lines is increased in order to improve the resolution, the foot last decreases and the viewing angle also becomes narrow. As a way to solve this problem, super
w1g+t8(L Birefringence
Ifeat(SBB), 5uper Twiate
d Nematic (8TN) was devised, and the luminance-applied 'trL8E characteristic became much steeper, and a display device with high capacity, high contrast, and wide viewing angle was obtained without using a switching element.

[Problem that the invention seeks to solve]

However, even in 5BIC and STH, the degree of elliptical polarization of the liquid crystal cell varies depending on the wavelength of light, resulting in coloration of yellow or dark blue. Therefore, it is difficult to see as a display device, and since complete white color cannot be obtained, when it is passed through a filter, only a murky color is obtained, making colorization impossible.

In order to solve this problem, methods such as 1. using the OM mode, using the Z guest-host mode, and using a pentagonal compensator were devised.

Method 1, using OM emode, has a single layer panel structure, so it can be manufactured using almost the same process as SBK and STN, and is also reflective and low cost. However, the black and white tone is insufficient.

The method of using Party B's guest host mode is 1. It has a single-layer panel structure similar to that of , and is a transmissive structure using dichroic dyes. This is not bright enough, and the black tone changes drastically depending on the viewing direction.

The method using an optical compensator (5) has a normal two-layer panel structure, and display quality such as contrast, brightness, and black-and-white color tone is close to that of CRT, and black coloring on a white background can be obtained.
So-called paper white display is possible. By combining this with a color filter, high-quality color display is also possible. Method 5 shows the best performance as a display device. In this method, a liquid crystal cell having the effect of a phase plate as an optical compensator is used in a structure in which the same liquid crystal material, the same cell gap, and the same twist direction but the same twist angle as the display liquid crystal cell are used. In the method of using this liquid crystal cell as a phase plate, manufacturing is difficult because control of the cell gap becomes delicate in order to match the liquid crystal cell for display and the liquid crystal cell for phase plate. Moreover, the number of liquid crystal cells is double the usual number, and the display device suffers from color changes depending on the viewing angle, and the weight of the unit becomes heavy, resulting in an increase in cost.

The present invention solves the above-mentioned problems and provides a simple, low-cost, high-contrast, lightweight, high-capacity display device with monochrome display.

[Means for solving problems]

The display device of the present invention is a display device that utilizes the birefringence of liquid crystal, and is characterized in that a chitin or chitosan film or sheet is disposed parallel to a display liquid crystal cell. In other words, chitin is a type of mucopolysaccharide, a natural polymer that is the main component of the hard shells of crustaceans such as crabs and shrimp. It consists of a long unbranched molecule consisting of βN acetyl-D glucosamine and exhibits optical activity. Chitosan is a deacetylated product of chitin.

Chitin and chitosan exhibit birefringence when formed into a film or sheet by dissolving it in an acetic acid aqueous solution and casting it, or by mixing it with PTA or the like and extruding it.

When this is combined with a liquid crystal display, it becomes SBE.

It can be used as an optical compensator, ie, a phase plate, to prevent coloring of STN.

To explain the present invention with the help of drawings, in Fig. 1, 1 is a polarizing plate serving as a polarizer, 2 is a liquid crystal cell for display, 3 is a chitin film phase plate for compensation or a chitosan film phase plate for compensation, and 4 is a detection plate. It is a polarizing plate that becomes photons. The polarization axis of polarizer 1 and the polarization axis of analyzer 4 are orthogonal,
When the signal IElIE is not applied, the display is black, which is a normally black display. As is clear from the figure, the present invention uses a chitin or chitosan film or sheet as a phase plate, unlike the conventional system in which a liquid crystal cell is used as an optical compensator. The incident light that passes through the polarizer 1 becomes linearly polarized light, and then passes through the display liquid crystal cell 2.
When the light passes through the liquid crystal, a phase difference occurs due to the birefringence effect of the liquid crystal, and the light becomes elliptically polarized light or circularly polarized light. Further, when the light passes through the optical compensation chitin film or chitosan film phase plate 3, it becomes linearly polarized light in the same polarization direction as that immediately after passing through the polarizer 1. This linearly polarized light cannot pass through the analyzer 4 whose polarization axis is in a crossed nicol state with the polarizer 1, and the display is black.

When a signal voltage is applied, the incident light that passes through the polarizer 1 becomes linearly polarized light, and since the display liquid crystal cell 2 does not exhibit a birefringence effect, it passes through as linearly polarized light, and chitin and chitosan for optical compensation are used. Only when the film reaches the m plate 3 does it become circularly polarized light or elliptically polarized light. This light passes through the analyzer 4 as linearly polarized light whose polarization axis is changed by 90 degrees from the original, and the display becomes white.

In the method of the present invention, since the chitin or chitosan phase plate for optical compensation does not utilize optical rotation, it is possible to obtain completely circularly polarized light, especially when displaying white when a signal voltage is applied, and in particular, Δ
If le x d is adjusted to π/4, a complete white display will be obtained. (Δl is the amount of birefringence of the chitin/chitosan film, and d is the thickness of the chitin/chitosan film.) While SBE and STN use 1M elliptically polarized light, the method of the present invention can use completely circularly polarized light. Since this is a display method, a completely white display, that is, paper white, can be obtained.

When a conventional liquid crystal cell was used as a phase plate for optical compensation, optical rotational dispersion remained and coloring was observed. In order to correct this, the optical rotation of the display liquid crystal cell and the optical compensation liquid crystal cell must be perfectly matched in manufacturing, which is extremely difficult to manufacture. On the other hand, since the chitin/chitosan film phase plate of the present invention has only a simple birefringence effect, completely circularly polarized light can be obtained, and the light that has passed through the analyzer becomes completely white light. Complete white light is 0N-OIF according to the present invention? Therefore, by combining it with a color filter, pure color display can be easily obtained, making full color display and multicolor display possible.

By completely displaying white color, a light pulp which is effective as a light pulp, has a high light transmission efficiency of 0N-07F, and has a high speed was obtained.

〔Example〕

Example 1 A liquid crystal cell with a twist angle of 180 degrees was used as a display cell, and a chitin film was superimposed on this to form a cross-niffle polarizer and analyzer, which was sandwiched between two polarizing plates.
By arranging a backlight behind it, a display device with a white display was obtained. The duty ratio was 200:1, and the viewing angles were +40 degrees and -30 degrees, respectively, with the left and right sides being +30 degrees, and no coloring due to changes in viewing angles was observed.

Example 2 A liquid crystal cell with a twist angle of 240 degrees was used as a display cell, and a chitosan film with ΔzXd of [1B was used as an optical compensation phase plate to obtain a monochrome display device. The contrast was 15:1 and the duty ratio was 400:1.

Example 3 A liquid crystal cell with a twist angle of 270 degrees was used as a display cell, and the casting direction of a chitin film as an optical compensation phase plate was shifted by 45 degrees from a polarizer and an analyzer to produce a black and white display device. Obtained. The duty ratio was 400:1.

Example 4 A monochrome display device was obtained by setting the polarization axes of a polarizer and an analyzer to be parallel, and using a chitosan film with Δn×d smaller than α8 as an optical compensation phase plate. The contrast ratio was 20:1.

Example 5 A reflective display device with black and white display was obtained with the configuration of 2 polarizers, a liquid crystal cell for display, a chitin film phase plate for optical compensation, and 2 reflectors for analyzer.

Example 6 A reflective display device with black and white display was obtained with the configuration of a polarizing plate, a chitosan sheet phase plate for optical compensation, a liquid crystal cell for display, and a metal reflecting plate.

Example 7 A full color display device was obtained with the configuration of a cold cathode tube backlight, a polarizer, a color film 2, a chitin film phase plate for optical compensation, and an analyzer. Use this to create a flat color TV
was also produced.

Example 8 An optical shutter anode comprising a polarizer, a liquid crystal cell array, a chitin film phase plate for optical reinforcement, and an analyzer was manufactured, and a DOS printer capable of high-speed response and high-contrast printing was manufactured.

〔Effect of the invention〕

According to the present invention, a display device with high contrast, high duty ratio, wide viewing angle, no color change due to viewing angle, light unit weight, easy manufacture, and low cost has been obtained. This not only has a paper white display performance comparable to that of a CRT, but also allows for full-color and multi-color display devices, making it possible to use it as a "wall-mounted TV." In addition, LOS printers, etc., which are effective not only as display devices but also as light valves, have high speed, and high contrast, have also been obtained.

[Brief explanation of the drawing]

FIG. 1 is a diagram explaining the present invention. 1...Polarizer 2...Liquid crystal cell for display 3...Chitin/chitosan film phase plate for optical compensation 4... ...Analyzer Figure 1

Claims (1)

[Claims] 1. A display device utilizing birefringence of liquid crystal, characterized in that a film or sheet of chitin or chitosan is disposed in parallel with a display liquid crystal cell.