JPH0218A - Orientation device and orientation method for liquid crystal display element - Google Patents

Abstract

PURPOSE:To easily form the monodomain of homogeneous orientation by locally heating the ferroelectric liquid crystal of a display cell and moving the heating region thereof. CONSTITUTION:The element 9 subjected to a rubbing treatment by forming an oriented film on one side is placed on a base 9 which is movable in a uniaxial direction at an assigned speed by a stepping motor 7 controlled by a computer 6. A bar-shaped heater 10 longer than the width of a picture element region is brought into line contact with the rubbing terminal side. Zigzag defects 2 before the treatment are eliminated and the area of the state II can be widened over the entire part of the picture element region if the temp. is set near the chiral smetic C phase-smetic A phase transition point in this state. The display at unequal densities is thus obviated.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a liquid crystal display device, and more particularly to an apparatus and method for aligning ferroelectric liquid crystal in a ferroelectric liquid crystal display element.

(Prior art) A liquid crystal exhibiting ferroelectricity in the chiral smecti 7 C phase and the chiral smecti H phase, and a ferroelectric liquid crystal are described by Mayer et al. (J-de, Phys, 36+69s 1975)
) was first synthesized and its existence was proven.

Clark and Lagerval (App1.Phys, Iet
t, 36°899.1980), an element consisting of a cell formed by encapsulating this ferroelectric liquid crystal in a cell with a narrow interval of about 1 to 2 pm and orienting it and two polarizing plates can be used at high speed. It has superior characteristics compared to conventional liquid crystal elements, such as response characteristics, memory effect, and high contrast ratio.

In order to develop such excellent properties not found in conventional liquid crystal electro-optical molecules, it is necessary to create homogeneously oriented seven domains in which all molecules in the liquid crystal cell are aligned in the same direction. Until now, some methods have been proposed as orientation methods.

For example, 1. 2. A method of gradually cooling from an isotropic phase to a liquid crystal phase while applying a magnetic field. A method of applying shear near the temperature at which the isotropic phase transitions to the liquid crystal phase, and ferroelectric liquid crystals are aligned in parallel along the cut surface of the polymer film during the transition from the 3° isotropic phase to the liquid crystal phase. Therefore, a method of applying an appropriate temperature gradient to epitaxially align the liquid crystal phase from the cut surface; 4. Control methods using alignment films (rubbing method, etc.), etc. Especially from the practical point of view, 4. This method is useful.

In order to achieve alignment by controlling the alignment film, the thermotropic ferroelectric liquid crystal is heated to bring the entire liquid crystal to an isotropic phase, and then slowly cooled to form the liquid crystal phase. By selecting an appropriate alignment film for the liquid crystal used, monodomains can be obtained relatively easily.

(Problem to be Solved by the Inventionff) However, in the monodomain thus obtained, a linear pattern of zigzag canes called a zigzag defect is often observed.

This defect may form an island-like loop (1) as shown in Figure 1 (a), or it may form a boundary as shown in Figure 1 (b), but in both cases, the zigzag is steep. A type (hereinafter referred to as lightning type C) and a gentle type (hereinafter referred to as hairpin type (3)) form a pair.

Further, the shading, color tone, etc. may differ under crossed nicol conditions on both sides of the boundary, and the overall appearance appears uneven, which causes a loss in quality as a display element.

(Means for Solving the Problems) The present invention makes it possible to eliminate zigzag defects that cause such display unevenness.

The principle is based on the difference in behavior with respect to local heating between the lightning type (2) and the hairpin type (3). That is, when heating the vicinity of each, the lightning-shaped zigzag (C) approaches the heated part (5), whereas the hairpin-shaped zigzag (3)
moves away. Further, when a portion away from the zigzag is heated, a new defect (4) is generated with the heating point as the boundary of the lightning pattern (2), as shown in FIG. Also, along with the zigzag movement, changes in color tone, etc. also move.

Therefore, the zigzag can be moved by appropriately selecting the setting position for quick cutting of the FA 4 and the direction of its movement. For example, the area of state H shown in FIG. 3 is expanded by the movement of the heated part (5), i! The entire i-area can be in state ■. Therefore, it is possible to eliminate the zigzag defect (a) from the pixel area.

(Detailed Description of the Invention) The present invention comprises means for locally heating the ferroelectric liquid crystal of a ferroelectric liquid crystal display element, and means for dragging and moving a heated portion on the element.

As the heating means, contact between the source and the element, or radiation can be used. As the contacting heat source, means capable of controlling heating, such as a heated gas such as air or a solid such as nitrates, can be used.

Further, as a radiation source, laser scanning, infrared rays, etc. can be used. However, the heating means are not limited to those listed above.

As a result of heating due to gas←, the temperature of the gas is determined by the temperature of the liquid crystal phase that exhibits ferroelectricity, such as the chiral smectic C phase and chiral smectific H phase of the ferroelectric liquid crystal used in the device, and its high-temperature side. Heating is controlled to a range near the transition point with the existing phase or higher than the transition point.

In this case, in addition to a hot air outlet that blows out air in the heating range to locally heat the element, a suction port whose main purpose is to suck in heated air is provided.

Further, if necessary, a means for cooling areas other than the heated portion may be provided.

In this case, in order to maintain the temperature difference between the non-heated part and the heated part and to make the non-heated region a liquid crystal phase exhibiting ferroelectricity, a cold air outlet is provided for blowing air at a temperature range below room temperature.

As a means for moving the heated part on the element, a heating means,
Alternatively, either or both of the elements may be moved.

(Example) (Example 1) A platform (8) movable in one axis direction at a specified speed by a stepping motor (7) controlled by a computer (6).
), a device (9) with a cell gap of 2 pm, which has been subjected to rubbing treatment with an alignment film formed on one substrate, is placed so that the rubbing direction and the moving direction are parallel, and a rod-shaped heater QOI that is longer than the width of the pixel area is placed on top of the substrate. was brought into line contact with the rubbing end side.

After fixing the heater 01 so that it does not move, set the temperature near the transition point of the chiral smectic C phase to the smectic human phase, and move the table (8) in the same direction as the rubbing direction. When it was moved, the zigzag defects and uneven display of shading that existed before processing disappeared and the entire image became uniform.

(Example-2) The alignment treatment of the liquid crystal display element was carried out in the same manner as in Example 1, except that the heater in Example 1 (1 (1) was a hot air heating mechanism Go having a cooling and suction mechanism). When we performed the process, the zigzag defects and uneven display of shading that existed before the treatment disappeared and the entire display became uniform.

(Effects of the Invention) It is possible to remove zigzag defects in a ferroelectric liquid crystal display element and unevenness caused by differences on both sides thereof, and a homogeneously aligned monodomain can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing a zigzag defect. FIG. 1 (a) shows an island-like defect, and FIG. 1 (b) shows a boundary case. FIG. 2 is a schematic diagram showing the effect of local heating. FIG. 3 is a schematic diagram showing the principle of the present invention. FIG. 4 is a diagram showing an orientation device. FIG. 5 is an explanatory cross-sectional view of the air heating mechanism 001. (1)... Island-shaped zigzag defect (2)... Lightning-shaped zigzag defect (3)...
・Hairpin-shaped zigzag defect (4)・・Newly generated zigzag defect (5)・・Heating part (6)・・Control computer ■・・Stepping motor <<8>>・・...Element installation stand (9)...Ferroelectric liquid crystal display element am...Heater, heating mechanism 03)...Hot air outlet 0 leak, 09--Suction port

Claims (1)

[Claims] 1) A ferroelectric device characterized by comprising a heating means for locally heating the ferroelectric liquid crystal of a ferroelectric liquid crystal display element, and a means for moving a heated portion on the element. Orientation device for liquid crystal display elements. 2) The apparatus for aligning a ferroelectric liquid crystal display element according to claim 1, wherein the heating means is gas. 3) Claim 1 characterized by comprising a cooling means for forcibly cooling an area other than the portion to be heated by the heating means.
An alignment device for a ferroelectric liquid crystal display element as described above. 4) A method for aligning a ferroelectric liquid crystal display element, which comprises locally heating the ferroelectric liquid crystal of the ferroelectric liquid crystal display element and further moving the heated region.