JPS58103577A - Color liquid crystal display element - Google Patents

Abstract

PURPOSE:To provide the titled display element which gives positive display with high display contrast and is capable of lowering and steepening threshold value, by adding a dichroic dye, an ionic material and a specified optically active material to a host liquid crystal having a negative dielectric anisotropy. CONSTITUTION:Substrates 1, 2 are apposed to each other at a given distance therebetween. Each of transparent electrodes 3, 4 is provided on an opposing side of each of the substrate. A liquid crystal 5 is enclosed in the space between the both electrodes. Said liquid crystal 5 is obtd. by adding a dichroic dye, an ionic material and further an optically active material of the formula to a host liquid crystal having a negative dielectric anisotropy. The opposing surfaces of the substrates 1, 2 are previously subjected to a vertical orientation treatment. Hence, no color is developed when no voltage is applied to the electrodes. When voltage is applied to the electrodes 3, 4, the dipole moment of the liquid crystal molecules is inclined to rotate in the direction of the electrical field, the molecules are revolved by the action of the ionic additive, and the dichroic dye as well as the liquid crystal molecules are brought into a disturbed state. Thus, positive display which has high contrast and is easy to observe from any directions can be obtd. By adding the optically active material, it is possible to steepen threshold value at a low voltage.

Description

DETAILED DESCRIPTION OF THE INVENTION A variety of color display modes using liquid crystals have been known. The example is related to places.

wh-Taylor! In the liquid crystal called Ml,
A nematic material having positive four-electron anisotropy containing an optically active monomer and a dichroic dye is interposed between nine substrates and is processed to be horizontally aligned or vertically aligned.

In the display mode of Jin's liquid crystal, when the voltage is OFF (no electric field) [
When the voltage is turned on (when an electric field is applied), the molecules are oriented perpendicular to the substrate surface, and a negative display with white spots is produced. This display mode has advantages such as bright color display without the need for a polarizing plate and a wide viewing angle. However, since it is a negative display, it is somewhat difficult to display. 1. In terms of display quality. There are some drawbacks such as some disadvantages.

Another display mode is one in which nematic liquid crystal, which has negative dielectric anisotropy including dichroic dyeing, is aligned obliquely to the substrate surface, and a polarizing plate is placed in front of the substrate surface. be. In this case, when the voltage is turned off, the molecules are arranged in a tilted arrangement with respect to the substrate surface, resulting in a slightly colored white outline. When the voltage is turned on, the molecules become horizontal to the substrate surface, resulting in a colored state due to the polarizing effect of the polarizing plate. This display Mobini 1. Because it is a Po9 display.

It has the advantage that the display is easy to read, but it requires a polarizing plate, which increases the cost.Under conditions of l1li temperature and high humidity, the gi roughness of the display element is determined by the durability of the polarizing plate.When the voltage is turned off, the molecular Because they are arranged at an angle with respect to the substrate surface, they are slightly colored, resulting in disadvantages such as poor display contrast as a whole.

Alternatively, the above-mentioned whtt.-Taylor type display mode can also be used in an inverted mode, that is, by interposing a nematic liquid crystal containing a dichroic dye and having a negative electromagnetic property between vertically aligned substrates. The positive type display mode is also misleading. However, if you try to keep the coloration low when the voltage is OFF by using a regular reflective sheet with a flat surface made of vinyl chloride, etc., there is a fee to make the dye density Wt extremely low, and the display contrast at a voltage of 5N will decrease. I can't make it too big. This is considered to be correlated with the inability to increase the cholesteric pitch generated when the voltage is turned on.

This invention was made in view of the points of the present invention, and its purpose is to utilize the change in the molecular arrangement of dichroic dyes generated from the m scattering mode (D8M) K to use the nine-table mode. By doing so, the display contrast tube can be sufficiently sharpened when the voltage is ON, and the threshold value can be maintained even when the voltage is applied. To provide a steepened Kafu liquid crystal display tube.

The display mode of the DAM of the present invention will be explained.

As shown in FIG. 1, the glass substrates *i11 and 121 are opposed to each other with a gap between the legs, and transparent electrodes +31 and 141 are formed on the opposing surfaces. Further, the substrate (i
A liquid crystal (5) is sealed in the gap of +21.C, the liquid crystal (5) is a mother liquid crystal with negative dielectric anisotropy, an optical oil substance, and a dichroic material. It contains a dye and an ionic substance. Also, one board 111, 12)
Vertical alignment treatment is applied to the facing surfaces of the substrates (11, +21), so that when no current is applied, the long axes of the liquid crystal molecules and the dichroic dye are aligned perpendicularly to the substrates (11, +21) as shown in Figure 1a). There is.

For this reason, it has high light transmittance, making it bright and beautiful on the base. In this state, the color of the dichroic dye does not appear. Therefore,
When voltage is applied between the electric images 131 and 141 by the power supply (6), the liquid crystal (5) in the form 11 of the same figure 1bl
As shown in Figure 2, the twin moment of the liquid crystal molecules tries to rotate in the direction of the first field, and the ionic additive added to the liquid crystal generates ions gt-, which causes the molecules to rotate. This will result in a chaotic state. Since the dichroic dye is also in a disordered state together with the liquid crystal molecules, the incident light is absorbed by the dichroic dye to produce a colored display. Since the dichroic dye is tilted at various angles in the above state, the colored display is easy to see from any direction, resulting in a positive display with high contrast.

Hereinafter, the present invention will be explained in more detail based on examples.

〔Example〕

An indium oxide-based transparent electrode film 1 is formed into a regular shape on a glass substrate, and then a silane coupling agent is applied and a vertically aligned tube is applied. Next, two glass substrates t are pressed against each other with a gap t of 10 μm maintained, thereby producing a g-crystal cell tube. Next, a liquid crystal material having the composition shown below was placed in a liquid crystal cell and sealed to produce a color liquid crystal display.

Mother liquid crystal 98.67-1% Negative dielectric anisotropy cyclohexa/carboxylic acid ester optically active material 0.65 t% Represented by the following formula 411. Alkyl base tube bed end with asymmetric carbon Phenyl ester cast conductor prepared for (*marked is asymmetric carbon) Dichroic dye 0.5”1%1.4-
7. Ionic substance 0.3"t%f trabutylammonium bromide as tyrene cast material The basic quality of the resulting color liquid crystal display element is shown in Figure 2. In the figure, the horizontal axis shows the liquid crystal display element. The voltage applied to the electrodes of the side panels, the vertical direction, and the vertical direction indicate the brightness of the finished display element, and the graph (graph) is that of the above example.

Graph (b) shows Example 1 in which no WjI scientific active substance was added to the above Example 1. Note that the brightness was detected by the voltage generated in the phototransistor.

As is clear from the figure, by adding an optically active substance, the threshold value can be made steeper at a lower voltage.

Therefore, as the optically active substance addition *W, the optically active substance '
The cholesteric pitch (P) (levorotatory) of the liquid crystal cell due to the addition of Jm′lj[
It is determined by the value of the ratio with dl, as shown in the table below.
, 0.64d/p 40.8. Good results were obtained by setting the additive concentration t by one step so as to obtain a range of 40.8.

In Table 1, the added concentration ffH, dichroic dye and ionic substance are expressed in -t% with respect to the mother liquid crystal.

(Table) As shown in the above, the present invention has the remarkable effect of using the 08M display mode, which makes the positive display with high 1 display contrast inferior, and also makes the threshold voltage lower and steeper. play.

[Brief explanation of the drawing]

FIG. 1 shows one color liquid crystal display according to the present invention. The same figure (&1 is a cross-sectional side view of the main part when no voltage is applied, the same figure (bl is a cross-sectional side view of the main part when voltage is applied, and Figure 2 shows the case where the optical oil-based substance is separated and the case where it is not separated. FIG. 3 is an explanatory diagram illustrating an optical change tube of a color crystal display system.

Claims (1)

[Claims] At least 10,000 of the two substrates are subjected to vertical alignment treatment,
In the color liquid crystal display element in which a liquid crystal substance is sealed in the chamber of the substrate, the quasi-crystalline material adds a dichroic dye and an ionic substance to the mother liquid crystal having jiL casting anisotropy,
Furthermore, an optically active substance we having the following structural formula. A color liquid crystal display element that is made of additives.