JP3258068B2 - Method for manufacturing ferroelectric liquid crystal device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a liquid crystal device, and more particularly to a method for injecting liquid crystal into a ferroelectric liquid crystal device.

[0002]

2. Description of the Related Art Ferroelectric liquid crystal devices are expected to be put to practical use in large-capacity displays and high-speed optical shutter heads for printers because of their memory properties and high-speed response in the order of microseconds. When a ferroelectric liquid crystal element is put into practical use, there is a technical problem in the orientation of liquid crystal.

Attempts to align ferroelectric liquid crystals at present are roughly divided into a method of rubbing an organic thin film and a method of obliquely depositing an inorganic insulator such as a metal oxide. In general, in the alignment method by the rubbing treatment, since the linear alignment defects due to the difference in the layer structure appear innumerably in the rubbing direction and the direction substantially perpendicular to the axial direction, the contrast ratio between the black level and the white level is significantly reduced. Also, it is difficult to have a memory characteristic, which is a great feature of ferroelectric liquid crystals.

On the other hand, the oblique deposition method can provide an alignment state with few alignment defects as described above, and in particular, a method in which a pair of substrates are opposed to each other as disclosed in JP-A-62-192724. By adopting a configuration of reverse tilt alignment in which SiO oblique deposition films having tilts opposite to each other are formed on a surface, a liquid crystal element having a memory property and a high contrast ratio can be obtained.

[0005] However, it has been found that uniform orientation cannot be obtained over the entire surface of a ferroelectric liquid crystal element based on reverse tilt alignment using a SiO obliquely deposited alignment film when the size of the liquid crystal element is increased. For example, a liquid crystal display element having a display area of about 10 cm square or a strip-shaped liquid crystal shutter element having a length of 25 cm and a width of 1 cm is described in JP-A-61-132926. With the conventional method of injecting a nodule into a low-viscosity liquid crystal state simply by heating the nodule, scratches on the outer periphery of the liquid crystal element, scratches on the alignment film surface, poor alignment, etc. are likely to occur, and production of ferroelectric liquid crystal elements Reducing the yield significantly.

Accordingly, it is an object of the present invention to provide a method for manufacturing a large-sized ferroelectric liquid crystal element which can improve the uniform alignment of the liquid crystal element and can be put to practical use.

[0007]

According to the present invention, an alignment film is formed on each of opposing surfaces of a pair of substrates having electrodes .
In the cell, the liquid crystal phase transition series is an isotropic-cholesteric-smectic A-chiral smectic C phase .
A method of injecting a certain ferroelectric liquid crystal cell, the cell
Cholesteric smectic and ferroelectric liquid crystal
The cell is heated at a constant temperature to the A phase transition temperature,
It is characterized by injecting into.

[0008]

The operation of the present invention will be described below with reference to the drawings. FIG. 4 shows that the phase transition series of the liquid crystal which changes with temperature is isotropic-cholesteric-smectic A-.
Each phase state of the liquid crystal, which is a chiral smectic C phase, is shown.
The liquid crystal molecules 43 sandwiched between 1 show a random state in the isotropic phase state (a), show a twisted arrangement between the upper and lower glass substrates in the cholesteric phase state (b), and decrease the twist pitch as the temperature increases. . In the smectic A phase state (c) and the chiral smectic C phase state (d), they are arranged almost uniformly along the surface pattern formed by the obliquely deposited alignment film.

Therefore, at the time of liquid crystal injection in which the liquid crystal molecules come into contact with the alignment film for the first time and are adsorbed, the smectic A phase and the chiral smectic C phase in which the direction along the surface pattern of the alignment film and the alignment direction of the liquid crystal molecules almost coincide. Ideally, the liquid crystal is heated to the state temperature, and the defect rate in the liquid crystal alignment state can be minimized.

On the other hand, in order to inject a large liquid crystal element into the whole element in a short time, it is desirable that the liquid crystal has low viscosity. However, in the smectic A phase and the chiral smectic C phase, the liquid crystal molecules form a layer state and are arranged. Therefore, the viscosity is as high as 1,000 centipoise or more, and poor injection is likely to occur. By the way, the viscosity of the liquid crystal decreases with an increase in temperature, but decreases with a rapid change to several tens of centipoise in the vicinity of the cholesteric-smectic A phase transition temperature, and the cholesteric pitch becomes infinite because the cholesteric pitch becomes infinite. It can be said that it is optimal as the injection temperature of the ferroelectric liquid crystal in which the liquid crystal phase transition sequence is an isotropic-cholesteric-smectic-A-chiral smectic-C phase, which is aligned in one direction almost coincident with the surface pattern of the oblique deposition alignment film. .

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic view showing a method of injecting a ferroelectric liquid crystal element according to an embodiment of the present invention, and shows a cell 11 before liquid crystal injection.
Is heated to a cholesteric-smectic A phase transition temperature between a heater plate 13 and a heat conducting plate 12 made of aluminum, and the liquid crystal material 14 in the liquid crystal reservoir 15 is also heated by the heater plate 16. Is heated to a constant cholesteric-smectic A phase transition temperature, and the exhaust port 17 is connected to a vacuum pump to reduce the pressure inside the bell jar.

When the inside of the bell jar 18 is sufficiently decompressed to a substantially vacuum state, the position of the heater plate 16 is raised and the liquid crystal injection port of the cell 11 is immersed in the liquid crystal. And the liquid crystal material 15 is injected into the device over about three hours. During that time, the cell 11 and the liquid crystal material 15 are kept constant near the cholesteric-smectic A phase transition temperature.

FIG. 2 is a schematic cross-sectional view of the cell used in the embodiment. The upper and lower glass substrates 21 to which a 1000 Å thick indium oxide transparent electrode 23 and an 800 Å thick SiO oblique deposition film 24 are attached. 22 is fixed by an epoxy resin seal 25 with a gap of 2.5 .mu.m, and a liquid crystal material is injected from the direction of 26 to produce a ferroelectric liquid crystal element.

FIG. 3 is a schematic plan view of the above-mentioned cell. The epoxy resin seal 35 has a strip shape of 1 cm in width and 25 cm in length according to the shape of a high-speed shutter for a printer.

A large number of the cells described above were manufactured, and the ferroelectric liquid crystal CS-1014, CZ-C100, and CZ-C manufactured by Chisso, whose liquid crystal phase transition series was an isotropic-cholesteric-smectic A-chiral smectic C phase.
C101, Hoechst liquid crystal CHC-005, CHC-0
06 and CHC-007 were injected into the cell near the cholesteric-smectic A phase transition temperature of the present invention to produce a ferroelectric liquid crystal device. % Or more. For comparison, Table 1 also shows the yield rate of ferroelectric liquid crystal devices manufactured at injection temperatures other than the present invention. From Table 1, 60% ~
The yield was only about 80%, indicating that the method of the present invention was extremely excellent.

[0016]

[0017]

As described in the above embodiments, according to the present invention, the direction along the surface pattern of the alignment film and the orientation of the liquid crystal molecule during the injection of the liquid crystal in which the liquid crystal molecule comes into contact with the alignment film for the first time are adsorbed. Since the alignment direction is almost the same, and the liquid crystal phase has a sufficiently low viscosity, it is possible to perform defect-free uniform alignment over a wide area, and to obtain a large number of ferroelectric liquid crystal elements at a high production yield. It is possible to provide a large-sized ferroelectric liquid crystal element which is possible and practical.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a liquid crystal injection method of the present invention.

FIG. 2 is a schematic sectional view of a cell used in an example of the present invention.

FIG. 3 is a schematic plan view of a cell used in an example of the present invention.

FIG. 4 is a schematic diagram showing a state of a liquid crystal phase.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Cell 12 Heat conductive plate 13 Heater plate 14 Liquid crystal material 15 Liquid crystal reservoir 16 Heater plate 17 Exhaust port 18 Bell jar 21 Lower glass substrate 22 Upper glass substrate 23 Transparent electrode 24 Oblique deposition alignment film 25 Epoxy resin Seal 26 Injection direction 31 Lower glass substrate 32 Upper glass substrate 35 Epoxy resin seal 36 Injection direction 41 Glass substrate 42 Oblique deposition alignment film 43 Liquid crystal molecules

Claims (1)

(57) [Claims] 1. A cell having an alignment film formed on opposite surfaces of a pair of substrates having electrodes and inclined with respect to the substrate surface.
In addition, the liquid crystal phase transition series is isotropic-cholesteric.
In a method of manufacturing a ferroelectric liquid crystal device in which a ferroelectric liquid crystal which is a cubic smectic A-chiral smectic C phase is injected , both the cell and the ferroelectric liquid crystal are cholesteric.
By heating to a constant temperature of the smuxic smectic A phase transition temperature,
Method for producing a ferroelectric liquid crystal device, characterized in that the injected from the direction along the inclination of the ferroelectric liquid crystal alignment film in the cell.