JPH0618891A - Liquid crystal element - Google Patents

Abstract

PURPOSE:To uniformly orient liquid crystal molecules and to obtain a good display free from unequal display by forming horizontally oriented films of silk fibroin protein. CONSTITUTION:A pair of transparent substrates 1, 2 consisting of glass, etc., are joined via a frame-shaped sealant 3 and a liquid crystal is encapsulated in the region enclosed by the sealant 3 between the two substrates 1 and 2. Transparent electrodes 4, 5 are respectively formed on the surfaces facing each other of the substrates 1, 2. The electrode forming surfaces of the substrates 1, 2 are coated with transparent insulating films 6, 7 consisting of silicon oxide, etc., and the horizontally oriented films 8, 9 for orienting the liquid crystal molecules A in a horizontal direction are formed on these insulating films 6, 7. The horizontally oriented films 8, 9 are formed of the silk fibroin protein obtd from cocoons of silkworms and the film surfaces thereof are subjected to an orientation treatment by rubbing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal device in which liquid crystal molecules are horizontally aligned.

[0002]

2. Description of the Related Art A liquid crystal device in which liquid crystal molecules are aligned in a horizontal direction has a TN (Twisted Nematic) mode,
There are STN (super twisted nematic) mode, horizontal alignment type of ECB (electric field control type birefringence) mode, and one using ferroelectric liquid crystal or antiferroelectric liquid crystal.

In these liquid crystal elements, a transparent electrode and a horizontal alignment film for horizontally aligning liquid crystal molecules are formed on the surfaces of a pair of transparent substrates facing each other across a liquid crystal layer. Has become.

The horizontal alignment film provided on the substrate of these liquid crystal elements is conventionally formed by applying a horizontal alignment material of polyimide on the substrate to form a film and rubbing the film surface in one direction. Has been done.

[0005]

However, in the conventional liquid crystal device in which the horizontal alignment film is formed of the above polyimide-based alignment material, the alignment state of the liquid crystal molecules is not uniform, which causes display unevenness. Had a problem. An object of the present invention is to provide a liquid crystal element capable of uniformly aligning liquid crystal molecules to obtain a good display without display unevenness.

[0006]

The liquid crystal device of the present invention is characterized in that the horizontal alignment film is formed of silk fibroin protein.

[0007]

The horizontal alignment film made of the silk fibroin protein has an alignment property for uniformly aligning the liquid crystal molecules over the entire alignment film. Therefore, the liquid crystal molecules are uniformly aligned to obtain a good display without display unevenness. be able to.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view of a liquid crystal element. In this liquid crystal element, a pair of transparent substrates 1 and 2 made of glass or the like are bonded via a frame-shaped sealing material 3, and liquid crystal is sealed in a region surrounded by the sealing material 3 between the substrates 1 and 2. The transparent electrodes 4 and 5 are formed on the surfaces of the substrates 1 and 2 that face each other. The electrode forming surfaces of the substrates 1 and 2 are covered with transparent insulating films 6 and 7 made of silicon oxide (SiO ₂ ), and the liquid crystal molecules A are formed on the insulating films 6 and 7. Horizontal alignment films 8 and 9 for horizontally aligning the are formed. The horizontal alignment films 8 and 9 are
Each of them is formed of silk fibroin protein obtained from silkworm cocoons, and its film surface is subjected to orientation treatment by rubbing.

The silk fibroin protein is prepared by scouring silkworm cocoons by the sodium carbonate soap method to remove sericin,
It can be obtained by dissolving the remaining silk fiber material in a mixed solvent of benzene: methanol = 2: 1 and extracting and removing lipid. In addition, a horizontal alignment film (hereinafter referred to as a silk fibroin alignment film) composed of the above silk fibroin protein,
9 is formed by the following method.

First, silk fibroin protein obtained from silkworm cocoons is dissolved in a scoured 8 mol LiBr aqueous solution, and the solution is filtered through a filter to remove insolubles and impurities. The solution is placed in a tube and dialyzed against distilled water, and the dialysis is terminated a few days after the Br ions in the dialysate are exhausted. Note that this dialysis is performed with care so as not to gel the fibroin.

Next, the concentration of the silk fibroin aqueous solution obtained by the above dialysis is adjusted according to the thickness of the alignment films 8 and 9 to be formed, and the silk fibroin aqueous solution is spin-coated to rotate the substrate at 100 to 5000 rpm. Are coated on the substrates 1 and 2, and the coated film is dried to form a silk fibroin film, and then the film surface of the silk fibroin film is rubbed in one direction to form alignment films 8 and 9. .

The silk fibroin alignment films 8 and 9 formed in this manner have the alignment irregularities found in the conventional horizontal alignment film made of a polyimide-based alignment material, and the liquid crystal molecules A are uniformly aligned over the entire alignment film. It has an orientation.

In the liquid crystal device of this embodiment, since the silk fibroin alignment films 8 and 9 having a uniform alignment property are formed on both substrates 1.2, the liquid crystal molecules A are uniformly distributed over the entire liquid crystal layer. Therefore, a good display without display unevenness can be obtained.

When the liquid crystal element is an active matrix element having a thin film transistor or the like as an active element, a conventional liquid crystal element in which a horizontal alignment film is formed of a polyimide-based alignment material has a poor voltage holding characteristic of the alignment film. hand,
Although flicker occurred on the display, the silk fibroin alignment films 8 and 9 had a larger surface energy than the conventional horizontal alignment film made of a polyimide-based alignment material, and therefore the change in the holding voltage of the pixel was different. Since the size is small, a good display without flicker can be obtained.

Further, when the liquid crystal element uses a ferroelectric liquid crystal or an antiferroelectric liquid crystal, in the above-mentioned conventional liquid crystal element, since the dielectric constant and surface energy of the polyimide-based alignment film are small, the alignment state of the liquid crystal However, the silk fibroin alignment films 8 and 9 have the problem that flicker occurs due to poor stability (stability of ferroelectric liquid crystal for bistability and stability of antiferroelectric liquid crystal for three alignment states). ,
Since its dielectric constant and surface energy are large, it is possible to improve the stability of the alignment state of the liquid crystal, improve the alignment memory property, and obtain a good display without flicker.

[0017]

According to the liquid crystal element of the present invention, since the horizontal alignment film is formed of silk fibroin protein, it is possible to uniformly align the liquid crystal molecules and obtain a good display without display unevenness.

[Brief description of drawings]

FIG. 1 is a sectional view of a liquid crystal element showing an embodiment of the present invention.

[Explanation of symbols]

 1, 2 ... Substrate 4,5 ... Electrode 6,7 ... Insulating film 8,9 ... Silk fibroin alignment film A ... Liquid crystal molecule

Claims (1)

[Claims] 1. A liquid crystal device in which liquid crystal is enclosed between a pair of transparent substrates provided with transparent electrodes and a horizontal alignment film, wherein the horizontal alignment film is formed of silk fibroin protein.