JPS5913222A - Color liquid crystal display element - Google Patents

Abstract

PURPOSE:To provide a liquid crystal display element of a negative display TN type having low transmittance of light and providing a sharp black color by incorporating a dye having a supplementary relation with the color shown by said element in a liquid crystal. CONSTITUTION:A liquid crystal 10 which is incorporated with a dye and is twist-oriented is sealed via a sealant 4 between two sheets of parallel transparent substrates 3 with transparent conductive films to form the cell of the element. A color filter 6 and a light diffusion plate 7 are further laminated on the outside surface of the substrates 3. The actual sealing of the liquid crystal is accomplished by (1) measuring the color coordinates of the liquid crystal display element of a TN type negative display by a color difference meter, (2) selecting a dye having the complementary relation with the measured color coordinates and incorporating the same into the liquid crystal, and (3) sealing the prepaired liquid crystal into the cell of the TN type. If a voltage is impressed to the display element and an observer 1 observes the same with the illumination from a light source 8, the display part having the hue shown by the display element and the background part showing a sharp black color by the dye are observed to the observer.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a color liquid crystal display element in which the background portion (non-voltage applied portion) is black.

Color liquid crystal display elements are constructed in such a way that the initial molecular arrangement of liquid crystal is changed to a different arrangement state by an external field such as an electric field, and the change in the optical properties of the liquid crystal cell accompanying this change in molecular arrangement is perceived as a color change. It is what was done. There are color liquid crystal display devices that display a display part in a predetermined color and a background part in black, such as those shown in FIGS. 1a and 1b, for example. The display element shown in FIG. 1a consists of two diagonal plates 8 of a cell in which twistedly oriented liquid crystal 5 is sealed between two transparent substrates 8 with transparent conductive films held in parallel with each other via a sealing material 4. A polarizing plate 2 is laminated on the outer surface, and the polarizing plate 2 on the light source 8 side
This is an exploded view of a TN type display element, in which a color filter 6 and a light diffusing plate 7 are further laminated in this order on the outer surface. When an electric field is applied to this display element and observed with illumination from a light source 8, the observer 1 can see that the color of the color filter 6 appears in the display area, but the color of the polarizing plate 2 itself appears in the background area. It has the disadvantage that the color is conspicuous and it looks dark or brownish.

The display element shown in Figure 1A is a disassembled display element made of the same parts as Figure 1A, except that it does not have the polarizing plate 2 on the light source side and uses a liquid crystal mixed with black pigment. In this case, the distance between the transparent substrates 8 is 10
Because it is narrow, about μ, there is a limit to mixing a large amount of black pigment into it, and it may be too bright and the background will not be black enough, so a color filter connected between the liquid crystal display element and the light source is inserted. When displaying multiple colors on a black background, there were problems such as the black being not vivid and the boundaries of the color filters appearing to be blurred.

In addition, there is a guest-host type liquid crystal display device in which liquid crystal molecules are homeotropically aligned or inclinedly aligned, and includes a dichroic dye, so that the display area is the color of the dye and the background area is colorless and transparent. In this case, the color of the dye mixed in the background appears, so in order to make the background an achromatic color and improve the contrast between the display area and the background, a pale yellow color filter, which has a complementary color relationship with the dye, is placed in the liquid crystal layer. A guest-host type liquid crystal display device stacked on the lower side is disclosed in Japanese Utility Model Application No. 57-22725. However, in this case, although the background part is made achromatic, there is a problem in that the display part is affected by the color of the color filter and the colors appear slightly different.

The present invention was developed by focusing on these conventional problems, and involves mixing into liquid crystal a pigment that is complementary to the hue exhibited by a TN type liquid crystal display element as a light shutter, thereby creating a bright black background in the background. The present invention will be described below with reference to the drawings, with the aim of solving the above problems by producing the following.

FIG. 2 shows a color display element as an example of the present invention.

The cell of this device has a liquid crystal 10 mixed with a dye and oriented in a twisted manner sealed between two transparent substrates 3 with transparent conductive films that are maintained in parallel with each other via a sealing material 4. A polarizing plate 2 is laminated on the outer surface, and a color filter 6 and a light diffusing plate 7 are laminated in this order on the outer surface of the polarizing plate 2 on the light source 8 side, but these are shown disassembled for explanation. When actually enclosing the liquid crystal, (1) measure the color coordinates of the TN-type negative display liquid crystal display element using a color difference meter, (2) select a dye that has a complementary color relationship to the measured color coordinates, and mix all the liquid crystals. (3) The prepared liquid crystal is sealed in a TN type cell.

For example, when measuring the color coordinates of the background part of a TN type negative display element using polarizing plate L-82-188 manufactured by Sanritsu Electric Co., Ltd.,
The hue was evening, as shown by point A in the chromaticity diagram of FIG. Therefore, 0.8% by weight of a dichroic dye G143 manufactured by Nippon Kanko Shiki Co., Ltd. corresponding to the complementary color yellow was mixed into the liquid crystal. As a result, the color coordinates are approximately the white point W, as shown by point B.
It started to overlap. Furthermore, the brightness decreased from 3.5 (point A) to 0.88 (point B), confirming the above effect.

The chromaticity diagram shown in FIG. 3 is originally three-dimensional, and the white point W represents the achromatic portion as the white point, which is actually black. It is obvious that complementary colors can be created by mixing several types of pigments. Since the amount of this dye is small and it is dichroic, the display area is not affected by this dye.

Therefore, when a voltage is applied to the display element shown in Fig. 2 and the display element is observed under illumination from the light source 8, the viewer 1 sees a display area having the hue exhibited by the display element and a background exhibiting a bright black color due to the pigment mixed in the liquid crystal. part is observed. In this case, the black color is sufficiently deep that the color filter reduces the transmittance of light and increases the blackness, and the color of the filter cannot be black. Therefore, even if filters of different colors are connected, it is not obvious that there are any filters of different colors, let alone the seams, so that multicolor display is possible.

In the 1611 drawing, the color filter 6 is shown to be laminated on the outside of the polarizing plate 2, but if a dye is added to the polarizing plate 4 and it also has properties as a color filter 6, a separate color filter 6 can be used. There's no need.

As explained above, in the present invention, the negative display T
By mixing into the liquid crystal a pigment that is complementary to the color exhibited by an N-type negative display element, it is possible to create a bright black color with low light transmittance, which has the effect of allowing it to be used as a high-performance light shutter. can get.

[Brief Description of the Drawings] The explanatory diagram, FIG. 8, is a chromaticity diagram. 1... Observer 2... Polarizing plate 8... Transparent substrate with transparent conductive film 4... Sealing material 5... Twisted oriented liquid crystal 6... Color filter 7... Light diffusing plate 8...Light source 9...Liquid crystal mixed with black dye IO...Liquid crystal mixed with dye and twisted and oriented. Patent applicant Nissan Motor Co., Ltd.

Claims (1)

[Claims] L In a color display element equipped with a TN type liquid crystal display element and a color filter for coloring the display part, the background part is made black by mixing a dye having a complementary color to the hue exhibited by the TN type liquid crystal display element into the liquid crystal. A color liquid crystal display element characterized by: