JPH0561014A - Liquid crystal display element - Google Patents

Abstract

PURPOSE:To excellently display a moving picture and to make display quality excellent. CONSTITUTION:A coloring compensating liquid crystal layer 22 is arranged on the one surface of a liquid crystal display cell 21, and the twist angle of the liquid crystal 12 of the liquid crystal layer 22 is made the same as the twist angle of the liquid crystal 7 of the liquid crystal display cell 21, the direction of the twist of the liquid crystal 12 of the liquid crystal layer 22 is reverse to that of the liquid crystal 7 of the display cell 21, and the retardation value of the display cell 21 is made >=1mum and the retardation value of the liquid crystal layer 22 is made 55-75% of the retardation value of the display cell 21.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION This invention has a liquid crystal twist angle of 1
The present invention relates to an STN (Super Twisted Nematic) type liquid crystal display device having an angle of 80 degrees or more.

[0002]

2. Description of the Related Art A STN type liquid crystal display device has a particularly excellent time-division driving characteristic because the transmittance-voltage characteristic has a steep threshold voltage value. Since the transmittance differs depending on the type, the transmitted light is colored.

In order to prevent such coloring, in a conventional liquid crystal display device, a color compensating liquid crystal layer is overlaid on a liquid crystal display cell as disclosed in Japanese Patent Laid-Open No. 130532/1990, and Japanese Patent Laid-Open Publication No. Sho. As shown in Japanese Patent Publication No. 61-89521, a liquid crystal display cell is overlaid with a phase plate.

[0004]

However, in such a liquid crystal display device, since the driving voltage is low, the response time is as slow as several hundred ms, so that the moving image display cannot be performed well and the contrast is not good. Since it is low, the display quality is not good.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a liquid crystal display device which can display a moving image well and has a good display quality.

[0006]

In order to achieve this object, in the present invention, in the STN type liquid crystal display element in which an optically anisotropic body is arranged on at least one surface of the liquid crystal display cell, the retardation of the liquid crystal display cell is used. Value is 1 μm
As described above, the retardation value of the optically anisotropic body is set to 55 to 75% of the retardation value of the liquid crystal display cell.

In this case, the optically anisotropic substance is used as a color compensating liquid crystal layer, the twist angle of the liquid crystal of the color compensating liquid crystal layer is set to be the same as the twist angle of the liquid crystal of the liquid crystal display cell, and the liquid crystal of the liquid crystal of the color compensating liquid crystal layer is The twist direction may be opposite to the twist direction of the liquid crystal of the liquid crystal display cell.

The optically anisotropic body may be a uniaxially stretched film, and the stretching axis of the uniaxially stretched film and the rubbing axis of the liquid crystal display cell on the side where the uniaxially stretched film is arranged may be substantially orthogonal to each other.

Further, the absorption axes of the polarizing plates of the liquid crystal display cell may be orthogonal to each other.

Further, the difference between the retardation value of the liquid crystal display cell and the retardation value of the optically anisotropic body is 250.
It is preferably set to 350 nm.

Further, the difference between the retardation value of the liquid crystal display cell and the retardation value of the optically anisotropic body is 550.
It is preferably set to ˜700 nm.

[0012]

In this liquid crystal display element, the driving voltage can be increased and the contrast can be increased.

Further, when the absorption axes of the polarizing plates of the liquid crystal display cell are made orthogonal to each other, the contrast can be further increased.

Further, the difference between the retardation value of the liquid crystal display cell and the retardation value of the optically anisotropic substance is 250 to 350.
When it is set to nm, it becomes a bright state when no voltage is applied.

Further, the difference between the retardation value of the liquid crystal display cell and the retardation value of the optically anisotropic body is 550 to 700.
When the thickness is set to nm, the state becomes dark when no voltage is applied.

[0016]

1 is a diagram showing a liquid crystal display device according to the present invention. In the figure, 1 and 2 are glass plates, 3 and 4 are transparent electrodes formed on the glass substrates 1 and 2, 5 and 6 are alignment films formed on the transparent electrodes 3 and 4, and 7 is glass substrates 1 and 2. With the liquid crystal enclosed between them, the retardation value Δnd of the liquid crystal 7
Is 1.74 μm, and the liquid crystal display cell 21 is composed of the glass substrates 1 and 2, the liquid crystal 7, and the like. Reference numerals 8 and 9 are glass substrates, 10 and 11 are alignment films formed on the glass substrates 8 and 9, and 12 is liquid crystal enclosed between the glass substrates 8 and 9.
The retardation value Δnd of the liquid crystal 12 is 1.14 μm, and the glass substrate 8, 9 and the liquid crystal 12 constitute the color compensation liquid crystal layer 22. 13 and 14 are liquid crystal display cells 2
1. A polarizing plate provided outside the color compensation liquid crystal layer 22.

FIG. 2 is a diagram showing the relationship of axes of the components of the liquid crystal display device shown in FIG. In the figure, 15 is a rubbing axis of the alignment film 5, 16 is a rubbing axis of the alignment film 6, and 17 is a rubbing axis.
Is the rubbing axis of the alignment film 10, 18 is the rubbing axis of the alignment film 11, 19 is the absorption axis of the polarizing plate 14, 20 is the absorption axis of the polarizing plate 13, the twist angle A of the liquid crystal 7 is 240 degrees, and the liquid crystal 12 is
The twist angle B of is 240 degrees in the reverse direction, the rubbing shaft 16,
The angle C formed by 17 is 90 degrees, the rubbing shaft 15 and the absorption shaft 20.
The angle D formed by and is 45 degrees, and the angle E formed by the rubbing axis 18 and the absorption axis 19 is 45 degrees.

In the liquid crystal display element shown in FIG.
As shown in FIG. 3, which shows the voltage-transmittance characteristic when a voltage is applied to the transparent electrodes 3 and 4 at a duty of / 200, a bright state is obtained at the point a and a dark state is obtained at the point b. Since the drive voltage can be increased, the response time is as fast as 80 ms for rising and 200 ms for falling, so moving images can be displayed well, and the display can be achieved when scrolling the word processor or personal computer, and when operating the mouse. Can be satisfactorily displayed.
Also, since the contrast ratio can be set to 17,
The display quality is good.

FIG. 4 is a diagram showing another liquid crystal display element according to the present invention. In the figure, reference numerals 26 and 27 denote transparent electrodes formed on the glass substrates 8 and 9, and the alignment films 10 and 11 are formed on the transparent electrodes 26 and 27.
The configuration is the same as that of the liquid crystal display element shown in FIG.

In the liquid crystal display element shown in FIG. 4, a voltage of 2.44 Vrms is applied between the transparent electrodes 26 and 27, and a voltage is applied to the transparent electrodes 3 and 4 at 1/200 duty. As is clear from FIG. 5 showing the rate characteristic, since the driving voltage can be increased and the response time is fast, the moving image can be displayed well and the contrast ratio can be set to 25. The display quality is good. Further, since the maximum transmittance is improved by 10% as compared with the liquid crystal display device shown in FIG. 1, it is possible to perform more excellent black and white display.

FIG. 6 is a diagram showing another liquid crystal display element according to the present invention. In the figure, 28 is a uniaxially stretched film made of polycarbonate, the retardation value Δnd of the uniaxially stretched film 28 is 1.14 μm, and the uniaxially stretched film 28 is arranged between the liquid crystal display cell 21 and the polarizing plate 14.

FIG. 7 is a diagram showing the relationship of axes of the constituent elements of the liquid crystal display element shown in FIG. In the figure, 29 is a stretching axis of the uniaxially stretched film 28, the rubbing axis 16 and the stretching axis 29 are orthogonal to each other, and the absorption axis 19 and the absorption axis 20 are orthogonal to each other.

In the liquid crystal display device shown in FIG. 6, as is apparent from FIG. 8 showing the voltage-transmittance characteristic, the driving voltage can be increased, so that the response time is fast.
Since the moving image can be displayed well and the contrast ratio can be set to 10, the display quality is good.

FIG. 9 shows that the retardation value Δnd of the liquid crystal display cell 21 is 1.22 μm and the retardation value Δnd of the uniaxially stretched film 28 is 0.92 μm, which is 1/200.
6 is a graph showing voltage-transmittance characteristics in the case of duty driving. As is clear from this graph, the display quality is good because the contrast ratio can be set to 8. Further, in such a liquid crystal display device, the response time is as fast as 80 ms for rising and 200 ms for falling, so that good moving image display can be performed. Also, since it is possible to make the light state when no voltage is applied,
Bright display can be obtained in positive mode.

FIG. 10 is a diagram showing another liquid crystal display element according to the present invention. In the figure, 30 and 31 are uniaxially stretched films made of polycarbonate, the retardation value Δnd of the uniaxially stretched films 30 and 31 is 0.57 μm, and the uniaxially stretched films 30 and 31 are the liquid crystal display cell 21.
And between the polarizing plates 13 and 14.

FIG. 11 is a diagram showing the relationship of axes of the components of the liquid crystal display device shown in FIG. In the figure, 32,
Reference numeral 33 is a stretching axis of the uniaxially stretched films 30 and 31, and the rubbing axis 16 and the stretching axis 33 are orthogonal to each other.
5 and the stretching axis 32 are orthogonal to each other.

In the liquid crystal display element shown in FIG. 10,
Display characteristics similar to those of the liquid crystal display element shown in FIG. 6 can be obtained.

In the above-mentioned embodiments, the color compensating liquid crystal layer 21, the uniaxially stretched films 28 and 3 are used as the optically anisotropic body.
Although 0 and 31 are used, other optically anisotropic bodies may be used.

[0029]

As described above, in the liquid crystal display device according to the present invention, since the driving voltage can be increased, the response time is fast, so that the moving image can be displayed well and the contrast can be improved. Since it can be increased, the display quality is good.

Further, when the absorption axes of the polarizing plates of the liquid crystal display cell are made orthogonal to each other, the contrast can be further increased, so that the display quality is further improved.

As described above, the effect of the present invention is remarkable.

[Brief description of drawings]

FIG. 1 is a diagram showing a liquid crystal display element according to the present invention.

FIG. 2 is a diagram showing a relationship between axes of components of the liquid crystal display device shown in FIG.

3 is a graph showing voltage-transmittance characteristics of the liquid crystal display element shown in FIG.

FIG. 4 is a diagram showing another liquid crystal display element according to the present invention.

5 is a graph showing voltage-transmittance characteristics of the liquid crystal display element shown in FIG.

FIG. 6 is a diagram showing another liquid crystal display element according to the present invention.

7 is a diagram showing the relationship of axes of the constituent elements of the liquid crystal display element shown in FIG.

8 is a graph showing voltage-transmittance characteristics of the liquid crystal display element shown in FIG.

FIG. 9 is a graph showing voltage-transmittance characteristics of another liquid crystal display element according to the present invention.

FIG. 10 is a diagram showing another liquid crystal display element according to the present invention.

11 is a diagram showing the relationship of axes of the constituent elements of the liquid crystal display element shown in FIG.

[Explanation of reference numerals] 13, 14 ... Polarizing plate 21 ... Liquid crystal display cell 22 ... Color compensation liquid crystal layer 28 ... Uniaxially stretched film 30, 31 ... Uniaxially stretched film

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Shinji Hasegawa, 3300 Hayano, Mobara, Chiba, Chiba Prefecture, within the Mobara Plant, Hitachi, Ltd. (72) Yoshio Hanada, 3300, Hayano, Mobara, Chiba, Hitachi, Ltd., within the Mobara Plant, Hitachi, Ltd.

Claims (1)

[Claims] 1. A STN type liquid crystal display device in which an optically anisotropic body is arranged on at least one surface of a liquid crystal display cell, wherein the liquid crystal display cell has a retardation value of 1 μm or more,
A liquid crystal display device, wherein the retardation value of the optically anisotropic body is 55 to 75% of the retardation value of the liquid crystal display cell.