JPH01105912A - Liquid crystal electro-optic element - Google Patents

Abstract

PURPOSE:To obtain a light crystal electro-optic element which is bright and has a high contrast by using a high-polymer compd. as the orientation-treated layers for a liquid crystal on the surface of base bodies having electrodes. CONSTITUTION:This liquid crystal electro-optic element consists of the base bodies 1 having the transparent electrodes, the rubbing-treated layers 2 consisting of the high-polymer compd. such as polyimide, liquid crystal 3, spacers 4 and layers 5 of the oriented high-polymer compds. The four embodiments consisting of such constitution and the two reference examples by the conventional method are compared. Then, the opening angle at the time of memory is about 30 deg. in the case of using the oriented films formed by orienting the high-polymer compd. by the rubbing treatment as the orientation-treated layers as with this liquid crystal element, while the opening angle at the time of memory in the conventional case of adopting the rubbing treatment of the high-polymer compd., i.e., polyimide as the orientation treatment method is about 15 deg.. The liquid crystal electro-optic element which is bright and has the high contrast is thus obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a liquid crystal device, and particularly to a liquid crystal device using chiral smectic liquid crystal.

[Conventional technology]

The liquid crystal element is at least transparent (1!) as shown in FIG. Substrate with poles 1. Rubbing layer such as polyimide 2. Enclosed liquid crystal 3. In particular, the rubbing layer 2 is an essential component for controlling the initial orientation of the sealed liquid crystal 3.

Conventionally, in liquid crystal elements using nematic liquid crystals, in order to control the initial alignment of liquid crystals, alignment treatment methods include:
Generally used methods include coating an organic material such as polyimide on the upper and lower substrates and performing a rubbing treatment, or performing oblique evaporation of SiO or the like on the upper and lower substrates.

[Problem that the invention seeks to solve]

However, in ferroelectric smectic liquid crystals,
The state of molecular aggregation is different from that of nematic liquid crystals, and while it is difficult to obtain uniform monodomains with good smectic liquid crystals using current alignment processing methods, even if monodomains are obtained, it is difficult to obtain alignments with good memory properties. Not necessarily. That is, the memory effect peculiar to ferroelectric smectic liquid crystals is greatly influenced not only by the orientation of liquid crystal molecules but also by the energy level resulting from the interaction between the liquid crystal and the substrate surface.

Moreover, the steep threshold characteristic is not only caused by the liquid crystal, but also by the condition of the substrate surface in contact with the liquid crystal. we,
As previously stated in Japanese Patent Application Laid-Open No. 59-214824, -
A liquid crystal electro-optical device was manufactured by applying polyimide to the surface of the substrate and subjecting it to a rubbing treatment, and using the surface of the substrate with the transparent electrode as it was left untreated. . However, although the orientation was very good, the above-mentioned effect and steepness of the threshold value were not sufficient.

There is another big problem with the rubbing method for polyimide films, which is a simple method for aligning ferroelectric liquid crystals. The reason is that the apparent opening angle in the bistable state becomes smaller due to rubbing.

The rubbing method imparts uniaxiality to the liquid crystal cell, and the liquid crystal molecules move from the position of the liquid crystal's original opening angle (which is twice the tilt angle of the molecule, hereinafter abbreviated as 2θ) in the direction of the rubbing axis. It has been reported by Wakita et al. that this is a result of attraction.

(National Technical Rep.
ort.

Vo135. No. 1 11'e'b, 1987) Furthermore, in JP-A No. 61-42618, we showed a method for aligning ferroelectric liquid crystals using a polymer compound exhibiting liquid crystallinity as an alignment film. When a magnetic field is used in the process, it takes a considerable amount of time to orient the polymer compound, resulting in poor productivity. Another problem is that the yield rate during mass production is also poor.

The present invention is intended to solve the above-mentioned problems, and its purpose is to provide a liquid crystal electro-optical element with good productivity that exhibits stable memory properties and good threshold characteristics.

[Means for solving problems]

The present invention is characterized in that a polymer compound is used as a liquid crystal alignment treatment layer on the surface of a substrate having electrodes. More specifically, the polymer compound is a polymer compound exhibiting liquid crystallinity, and the liquid crystal polymer is oriented by rubbing, and the liquid crystal polymer is used as an alignment film. There is.

〔Example〕

The present invention will be specifically explained with reference to Examples below, but the effects of the present invention will be demonstrated by the compounds used in the Examples.

The present invention is not limited to liquid crystal materials, and similar effects can be obtained using other polymer compounds or other liquid crystal materials.

In addition, FIG. 1 shows a cross-sectional view of an example of the liquid crystal "d!" of the present invention and an air optical element. 1 is a substrate having a transparent electrode, 2 is a rubbing treatment of a polymer compound such as polyimide j-13 is a liquid crystal , 4 is a spacer, 5 is 1- of the oriented polymer compound
represents.

Example 1 Polyimide was coated on the surfaces of two substrates having transparent electrodes using a spinner, and baked at 270° C. for 30 minutes. Thereafter, a rubbing treatment was performed on the surface of one of the substrates.

A polymeric liquid crystal compound with the following structural formula ("0-o-0(CH2)s O+0-O-o-0(O
H2) A 7wt% α7wt% tetrahydrofuran solution on the order of o−+n was prepared and applied to the surface of the first substrate subjected to the rubbing treatment using a spinner. Heat treatment was performed at 150° C. for 15 minutes, and tetrahydro 7 run was blown off to maintain the present polymer compound in a liquid crystal state and align it in the rubbing direction.

The two thus obtained oriented substrates were adhesively sealed via a spacer, and ferroelectric liquid crystal was injected under pressure or under reduced pressure to produce a liquid crystal 'tjL' pneumatic optical element. In this cell, the ferroelectric liquid crystal is in the rubbing direction, i.e.
It was oriented in the long axis direction of the molecules of the polymeric liquid crystal compound, forming a uniform monodomain. The ferroelectric liquid crystal compound used was
It is O3-1011 manufactured by Chisso Corporation. ±1 for this liquid crystal cell
When the memory property was evaluated by applying a pulse of 5 cm, the opening angle at the time of memory was 31 degrees.

Example 2 Polyimide was coated on the surfaces of two substrates having transparent electrodes using a spinner, and baked at 270° C. for 60 minutes. Thereafter, rubbing treatment was performed on the surfaces of the two substrates.

A 0.7 wt % tetrahydrofuran solution of a polymer compound having the structural formula shown below was prepared and applied to the surfaces of the two substrates subjected to the rubbing treatment using a spinner. A heat treatment was performed at 160° C. for 15 minutes to remove the tetrahydrofuran, and the polymer compound was kept in a liquid crystal state and oriented in the rubbing direction. The two thus obtained aligned substrates were adhesively sealed via a spacer, and ferroelectric liquid crystal was injected under pressure or under reduced pressure to produce a liquid crystal electro-optical element. In this cell, the ferroelectric liquid crystal was oriented in the rubbing direction, that is, in the long axis direction of the molecules of the polymeric liquid crystal compound, forming a uniform monodomain. The ferroelectric liquid crystal compound used was C! manufactured by Chisso Corporation. 3-1
It is 011. When we applied a ±15V pulse to this liquid crystal cell and evaluated its memory properties, the opening angle in the memory state was 3.
It was 0 degrees.

Example 3 Polyimide was coated on the surface of one substrate having a transparent electrode using a spinner, and baked at 270'O for 30 minutes. Thereafter, the surface of the substrate was subjected to a rubbing treatment.

Polymer compound with the following structural formula +0-@-coo-@-000(OH,)a co-)
, α5% of .

A form solution was prepared and applied to the second surface of the first substrate subjected to the rubbing treatment using a spinner.

A heat treatment was performed at 80° C. for 15 minutes to evaporate chloroform, and the polymer compound was kept in a liquid crystal state and oriented in the rubbing direction. A liquid crystal electro-optical device was prepared in the same manner as in Example 1 using the two alignment-treated substrates thus obtained.

In this cell as well, the ferroelectric liquid crystal was oriented in the rubbing direction, that is, in the long axis direction of the molecules of the polymeric liquid crystal compound, forming a uniform monodomain. The ferroelectric liquid crystal compound used was O3-1011 manufactured by Chisso Corporation. ± to this liquid crystal cell
When a 15V pulse was applied and the memory property was evaluated, the opening angle during memory was 29 degrees.Example 4 The polymer compounds in Examples 1 and 2 were polymers with the following structural formula (% formula %) When a liquid crystal electro-optical device was produced in the same manner as in Examples 1 and 2 except for the compound, the same effects as in Examples 1 and 2 were obtained.

Reference Example 1 L-imide was applied to the surfaces of two substrates having transparent electrodes using a spinner, and baked at 270° C. for 30 minutes. Thereafter, the surfaces of the two substrates were subjected to a rubbing treatment. The two thus obtained aligned substrates were adhesively sealed via a spacer, and ferroelectric liquid crystal was sealed under pressure or under reduced pressure to produce a liquid crystal electro-optical device. In this cell, the ferroelectric liquid crystal molecules were aligned in the rubbing direction and exhibited uniform monodomain properties. The liquid crystal used was C5-101 manufactured by Chisso Corporation.
It is 1. When a pulse of ±15 V was applied to this liquid crystal cell to evaluate the memory property, the opening angle during memory was 13 degrees.

Reference Example 2 Polyimide was coated on the surfaces of two substrates having transparent electrodes using a spinner, and baked at 270° C. for 30 minutes. Thereafter, the surface of one substrate was subjected to a rubbing treatment. In this way, the two substrates obtained after alignment treatment are adhesively sealed via a spacer, and ferroelectric liquid crystal is sealed under pressure or under reduced pressure to form a liquid crystal! A pneumatic optical element was created. In this cell, the ferroelectric liquid crystal molecules were aligned in the rubbing direction and exhibited uniform monodomain properties. The liquid crystal used was O3-1011 manufactured by Chip Co., Ltd.
It is. When a pulse of ±15 V was applied to this liquid crystal cell to evaluate the memory property, the opening angle during memory was 15 degrees.

〔Effect of the invention〕

The effects of the present invention will become clear with reference to the above-mentioned Examples and Reference Examples. In other words, the opening angle when memory is conventionally oriented by rubbing kerimide on a polymer compound is around 15 degrees, whereas in the present invention, the opening angle is around 15 degrees when a polymer compound is oriented by rubbing with kerimide. When used as a layer, the opening angle during memory is approximately 30 degrees, making it possible to provide a bright, high-contrast liquid crystal electro-optical element.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of an example of the liquid crystal electro-optical element of the present invention. FIG. 2 is a diagram showing an example of a cross-sectional view of a conventional liquid crystal electro-optical element. 1... Substrate 2 having a transparent uA electrode
Rubbing layer of zariimide etc. 3 Enclosed liquid crystal 4 Spacer 5 Layer plate of oriented polymer compound Applicant Seiko Epson Co., Ltd. Agent Patent attorney Mogami (1 other person) t:), (,+,',,9...

Claims (4)

[Claims] (1) A liquid crystal electro-optical element characterized in that a polymer compound is used as an alignment treatment layer for liquid crystal on the surface of a substrate having electrodes. (2) The liquid crystal electro-optical element according to claim 1, wherein the polymer compound is a polymer compound exhibiting liquid crystallinity. (3) Claim 1 or 2, characterized in that the long molecular axes of the polymer compound are aligned in one direction.
The liquid crystal electro-optical device described in 2. (4) The liquid crystal according to any one of claims 1, 2, or 3, wherein a rubbing method is used as a means for aligning the long molecular axes of the polymer compound in one direction. Electro-optical element.