JPS58152221A - Color liquid crystal display - Google Patents

Abstract

PURPOSE:To obtain a sharp color display by sealing a liquid crystal compsn. having a smetic phase and dichromatic dyes between a pair of substrates which are provided with transparent electrodes serving also as heating resistors on at least one substrate and have vertically oriented surfaces, and acting heat and an electric field thereto. CONSTITUTION:An element wherein a mixture of a liquid crystal compsn. 3 consisting of >=50wt% a liquid crystal having a chiral smetic liquid crystal phase C (SmC) exhibiting a smetic phase A or hexagonal smetic phase B at around an ordinary temp and the balance nematic liquid crystal compsn. 3 of negative dielectric anisotropy and dichromatic dyes 4 is sealed into a cell provided with transparent electrode 6 serving also as heating resistors on at least one substrate 2 and provided with ordinary transparent electrodes 5 on the other substrate 1 and are applied with vertical orientation on both substrates is made. When electric pulses are applied to the electrodes 6, the liquid crystal molecules and dyes in said parts change to an isotropic or nematic phase, and are thus displayed in a color. When the electric pulses are eliminated, the temp. decreases quickly and the original colorless phase is restored. If the display is held colored and is cooled under application of an electric field between the same and the counter electrodes, the SmC state is formed, and in this state the colored display remains even if the application of the electric field is ceased.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a color liquid crystal display element that is produced by injecting a mixture of compounds exhibiting liquid crystallinity into a liquid crystal cell formed by special treatment on a glass substrate. , In detail, the liquid crystal compound is smectic (Smectl).
c) It relates to a color liquid crystal display element which is a compound having a phase.

In general, the operating principle of a liquid crystal display element is that an electric field*1 is applied to a liquid crystal layer formed between two or more glass substrates arranged in parallel and facing each other. This change is based on a change in properties, and this change is caused by the special initial orientation of the liquid crystal when no electric field is applied being deformed or disturbed when an electric field is applied.

The main methods of electro-optical devices using liquid crystal display elements include D.
8 (Dynamic 8 catterlng), D
AP (Deformation of vertica)
EYA gned Phasesl, TN (Tw1st
edNematlc), and PO (Phase Oh
The D8%DAP and TN methods mainly utilize the characteristics of the nematic (Nematlc) phase of liquid crystals, while the latter PC method mainly uses the nematic phase and cholesterol phase. Reick (Oholes)
This method utilizes the phase transition phenomenon of the tarlc) phase. In addition, the Guest-Host3 method, which combines these methods with the addition of dichroic dyes, has recently been studied.In this way, the liquid crystal phase studied in the conventional method is The target phases are the nematic phase and the cholesteric phase.These liquid crystal phases have lower viscosity than the other liquid crystal phase, the smectic phase, and are more likely to enter the liquid crystal state near room temperature, and are more sensitive to electric fields, etc. Because it has characteristics such as high sensitivity, it has become a center of applied interest.

However, for example, when adding the dichroic dye, in either method, it can be in a single colored state, or it can be oriented perpendicularly to a substrate such as glass to utilize a nematic state, and a non-colored state (
Strictly speaking, the display is performed by controlling both the layer state (slightly colored and layered state) using an electric field, but those with good contrast are
The current situation is that nothing has been achieved. There are many reasons for this, but one problem with the liquid crystal itself is that there is a limit to the order parameter (degree of order) of nematic liquid crystal. In other words, due to the low order parameter, all molecules are not perfectly aligned perpendicularly to the glass substrate in terms of molecular order, and what would normally be in a state close to uncolored becomes colored. However, due to this, the contrast may be reduced. One possible way to solve this problem is to apply smectic liquid crystals with a high degree of order, but there is little active research.
The current situation is that nothing that is practically satisfactory has yet been announced.

The present invention has been carefully designed to solve the above-mentioned problems.Chiralus At least near room temperature, it is a smectic (amA) phase or a hexagonal smectic B (H-8m B) phase, while at high temperatures it is a nematic phase, a rim phase. By injecting a liquid crystal composition that is a mixture of a liquid crystal (N1) with negative pyrogenic anisotropy and a dichroic dye, and displaying using heat and an electric field, a color liquid crystal with a high contrast positive display is created. The present invention provides a display element.

Hereinafter, the uninvented color liquid crystal display device will be celebrated with reference to the drawings. First, in Figure 'IJ41 (a) K, in the initial state, the glass substrate m, (21 surface VC is given vertical alignment, the liquid crystal molecules (3) are held at 8 mA or ■ mother state). , and the dye (4) also follows this.Therefore, in this state, the state is extremely close to being uncolored.

Next, in Figure 1(b), one glass substrate +21
In the 1c setting, it is easy to apply a short current pulse to the electrode (6) which also serves as a heating resistor, and selectively bring the liquid crystal molecules (3) into an isotropic liquid state only in that part. Since the dye (4) in is isotropic, it is colored and becomes a layer state. When the current pulse is erased, the temperature suddenly drops f5 and the liquid crystal molecules (3) become an isotropic liquid state. is the first
The substrates (1;, (21) in Figure (c) are oriented horizontally with f
After passing through the nematic phase (next to Nn liquid crystal), it immediately returns to the 8mA or H-8mB dimension shown in Figure 1 (a) and becomes an uncolored state. Here, when the liquid crystal molecules (3) are in an isotropic liquid or nematic phase state, the electrodes (6
) and the friend electrode (5) facing it, and continuing to connect the cooling tube while applying an electric field to that part, it returns to the smectic state while remaining horizontal, and the 8 mO state ( The liquid crystal molecules (3) are in a layered state, and the substrate (11, (2+) is in a spiral shape in the direction parallel to it).The current flowing through the electrode (6) is minute, so it does not generate heat, and this state erases the voltage. Therefore, the colored state 1!! remains and is memorized.In other words, depending on whether or not a voltage is applied during the cooling process, memory property can be imparted to the display. Needless to say, the 0 display contrast that can be achieved is better than that of conventional types because the 8mA or H-8mB phase, which has a higher degree of order than nematic liquid crystal in the initial state, is used.

Hereinafter, a more detailed explanation will be given based on examples.

Example 1゜ITO was applied to the opposing surfaces of a pair of glass substrates using a general method.
A film consisting of indium chloride and oxide) is formed into a desired shape, and serves as a transparent electrode that also serves as a heating resistor, and a normal transparent electrode opposite to this.

Next, these ITOIIs are placed on the surface of the glass substrate.
0 Mushroom - Ingot - A transparent coating consisting of sOs-based oxide was applied, and further, vertical alignment treatment was performed with myristic acid polynuclear Affi complex, and 10 μm thick was applied using epoxy adhesive.
Create a gap liquid crystal cell. Liquid crystals of various mixed compositions containing dichroic dyes are injected into this to create a color liquid crystal display element.

Therefore, in the color liquid crystal display element, the display effect of the composition ratio of the liquid crystal to be injected was investigated. The mixed liquid crystals studied are as follows.

Liquid crystal containing smectic physiognomy and chiral smectic 0 phase ÷000be>R
'(R,R'-alkyl group or alkoxy group, etc.) dichroic dye 1 wt 1.5-diano 4.8-dihydrogen 2-P-bentroxybenzyl NH* 0 0H Results are below (table) As shown.

(Table) *As is clear from the (Table), when the amount of added liquid crystal having 8 mA and 8 mO is 50 wt 4 or more, it has memory properties. Moreover, it was found that the color liquid crystal display element has a high display contrast, and only the conventional nematic liquid crystal (
It can be seen that it exhibits extremely superior properties compared to those of X-OqG). In addition, a similar study was carried out for the case where the number of carbon atoms in the structural formula of smectic liquid crystal was changed from 3 to 12, but results were almost the same, although there was a slight change in the amount of addition that indicates memory properties. is obtained.

Example 2 A liquid crystal cell similar to that in Example 1 was prepared, and a similar study was conducted using a liquid crystal with the following structural formula that outputs 8 mA and *8 mO. Almost the same results were obtained. to 0 meeting H violence

[Brief explanation of the drawing]

131(a) to (d) are explanatory diagrams showing the operating principle of the color liquid crystal display element of the present invention. (11, (2) Glass substrate, (3) Liquid crystal molecules, (4
) Dichroic dye, (5) Electrode, (6) Electrode that also serves as a heating resistor Figure 1 (C) Procedural amendment (method) % formula % 1. Case display axis Sho 57-34622 No. 3 Amendment Relationship with the case of the person who filed the patent application Patent applicant: 1-7 Yukitani Otsuka-cho, Ota-ku, Higashijuto, 1-7, Yukitani Otsuka-cho, Ota-ku, Higashijuto, June 11, 1980, Figure 1, F: Attached to 4 t; Correct as shown in the drawing. Figure 1 (Qn (
b (C) (d) Procedural amendment (voluntary) November 19, 1980 Patent Office Ryomiya 1, case indication patent application No. 1983-34622 2, name of Akira Hamaguri color liquid crystal display device 3, amendment Relationship with cases involving persons who engage in
+ 1 (representative) 4 correction target gates m 5, 工,. ,,, Jyo 〆1.7° As per attached sheet
' The scope of the claims is amended as follows. In a liquid crystal display element in which an alignment agent is added and a liquid crystal composition is injected between the two layers, the liquid crystal composition It has a C phase, exhibits a smectic physiognomy or hexagonal smectic Ba at around room temperature, and has a nematic phase with negative anisotropy,
Furthermore, a color liquid crystal display element characterized by adding a dichroic dye and consisting of f:

Claims (1)

[Claims] (1; At least one of a pair of substrates such as glass,
In a liquid crystal display element, a heating resistor is provided, a direct aligning agent is applied to the opposing surfaces of both substrates, and a liquid crystal composition is injected into a tube between both substrates. It has a smectic physiognomy or a hexagonal smectic B phase in the vicinity of normal current and has a nematic phase with negative electrocasting anisotropy, and furthermore, it has a dichroic color X added. A color liquid If & display element characterized by being defeated from. (21 enemy am parabola, in the initial state, uncolored due to smectic physiognomy or hexagonal smectic B phase,
Colored by a directional liquid phase by heating, a directional liquid phase,
Alternatively, the color liquid crystal display element according to item 1 of the patent claim, characterized in that a layered color form is memorized by a chiral smectic zero phase that emerges by cooling while applying an electric field in the nematic phase.