JPS5945125B2 - Liquid crystal cell orientation control method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a liquid crystal cell, and more particularly to a method for controlling the alignment of a liquid crystal cell with improved heat resistance.

Conventionally, liquid crystal cells used for earth play, light control devices, decorative boards, etc. have a pair of electrode plates facing each other at a predetermined interval, the periphery is sealed with a sealing material, and the liquid crystal is sandwiched between the electrode plates. Are known.

As a method for sealing these liquid crystal cells, there are two methods: sealing with an inorganic sealant such as low melting point glass, or sealing with an organic sealant such as epoxy resin or Natsumachi plastic resin. be. For such liquid crystal cells, various surface treatment methods are known in order to orient liquid crystal molecules in a certain direction on the surface of the electrode plate. Vapor deposition and rubbing methods are known as methods for controlling the orientation of electrode plates, and methods for controlling orientation by vapor deposition include SIO, SlO2, MgF2, Ca
An oriented material such as F2, Au, Cr, etc. is formed in a direction perpendicular or oblique to the surface of the electrode plate by vacuum evaporation, sputtering, or other ordinary evaporation methods. This orientation control method using vapor deposition has sufficient heat resistance and can withstand heat treatment conditions such as low melting point glass seals, but vapor deposition has disadvantages such as complicated cell manufacturing processes and poor workability. be. On the other hand, in the orientation control method using a rubbing method, the surface of the electrode plate is rubbed in a certain direction with gauze, felt, paper, special chemical fiber, etc. to form an orientation control surface. Although this rubbing method has good workability and is suitable for industrial use, it has the drawback that it cannot be used for sealing with highly reliable fluoropolymers or low-melting glass because the heat resistance of the orientation control force is insufficient. be. Recently, a method has been proposed as a heat-resistant rubbing method in which the surface of an electrode plate is rubbed with powders of boron nitride, molybdenum sulfide, or tungsten sulfide interposed therein to coat the surface with a thin film.

Such known documents include JP-A-50-117452, JP-A-51-26562, and JP-A-51121.
There is a publication No. 353. The orientation control surfaces obtained by these known methods are heat resistant, but because they use powder, the orientation is not uniform, and the powder scatters during work, causing problems in the work environment. However, because it was difficult to maintain a constant supply of powder, there were problems with workability and reproducibility.

As a result of repeated studies based on recognition of the above-mentioned problems, the present inventor found that the shape of the solid lubricant improves the workability of orientation control.
We have come to the conclusion that this is related to stability.

The present invention has been made based on the above study results, and the solid lubricant is supplied in the form of a block, the solid lubricant in the form of a block is wrapped by a wrapping roller, and the wrapping roller to which the solid lubricant is attached is used to form an electrode. It is characterized by wrapping the board.

Examples of the solid lubricants used include boron nitride, molybdenum sulfide, tungsten sulfide, sekiboku, ummo, talc, stonestone, and zinc white.

Since the orientation control method of the present invention uses block-shaped solid lubricant, it is possible to supply a constant supply of solid lubricant over a long period of time, and it is reproducible and has excellent workability without powder scattering. In addition, an excellent product with stable orientation force can be obtained.
This is because when the wrapping roller wraps the block-shaped solid lubricant, interlayer peeling of the solid lubricant occurs uniformly over a wide area, and the solid lubricant adheres to the wrapping roller and then wraps the electrode plate. It is believed that good orientation is obtained because uniform coating is applied through the rollers. Next, it will be explained based on the drawings.

FIG. 1a shows a conventional wrapping method for supplying a powder solid lubricant.

In this method, the electrode plate 2 is fixed on the wrapping table 1, the wrapping roller 14 is rotated, and the wrapping table 1 is moved from side to side while supplying the powder solid lubricant 5 to perform wrapping. . When wrapping is performed using this method, a heat-resistant orientation control surface is formed, but when the electrode plates whose orientation has been controlled using this method are assembled so that the wrapping directions are perpendicular to each other, P-type liquid crystal is injected, and observed using a polarizing microscope. As shown in Figure 1b, there are dot-like and meteor-like alignment defects, and the reproducibility is poor. FIG. 2 shows an example of the present invention, in which a wrapping table 1
A groove is provided in the groove, and the electrode plate 2 is fixed in the groove in a predetermined direction, and a block of solid lubricant 3 is fixed in a part of the groove.

A wrapping roller 4 wrapped with cloth such as gauze is rotated in a fixed direction, and the wrapping table 1 is moved left and right. When the wrapping roller 14 wraps the solid lubricant 3, a thin layer of the solid lubricant 3 is applied to the wrapping roller 14.
When the wrapping table 1 moves and wraps the electrode plate 2, the solid lubricant is transferred to the surface of the electrode plate 2 and forms an orientation control surface. The block-shaped solid lubricant of the present invention is not limited to a plate-like shape, and may have an irregular shape such as a columnar shape, and is not limited in shape.

Further, the installation position of the block-like solid lubricant is not limited to the lapping table, but may be any position as long as it comes into contact with the lapping roller as shown in FIG. In the present invention, after wrapping the electrode plate with a wrapping roller coated with a solid lubricant as described above, the uniformity of the orientation control surface can be further improved by wrapping the electrode plate with a wrapping roller coated with no solid lubricant. This results in highly desirable results.

As explained above, the liquid crystal cell of the present invention uses the above-mentioned orientation control method, and as a result, it is a heat-resistant wrapping and has significantly improved workability, stability, and reproducibility, and in turn, significantly improves the reliability of the liquid crystal cell. can do. Example: An electrode plate was prepared by forming a film of patterned indium oxide on a glass plate with a thickness of 2.5 mm. After cleaning, the electrode plate was deposited at 6 to 8 x 10 -5 t0r by electron beam evaporation.
A SiO2 film was evaporated at 2,000λ under the conditions of r and heated at 5000C.
Firing was performed for 30 minutes.

After cleaning this electrode plate, it was fixed on a lapping table to which boron nitride was fixed as shown in FIG. 2, and lapped back and forth 5 times. Next, this electrode plate was washed by wrapping it three times with a new wrapping roller. A low melting point glass was printed around the electrode plate whose orientation was controlled in this manner, and another electrode plate was stacked so that the wrapping directions were perpendicular to each other, and heat sealed at 520° C. for 30 minutes to purchase a cell. When P-type liquid crystal was injected into this cell and observed under a polarizing microscope, a liquid crystal cell with a uniform twisted orientation without defects was obtained. As a result of subjecting this liquid crystal cell to a 60°C, 90% humidity test, it was found that
There was no change in the orientation characteristics even after the passage of time.

[BRIEF DESCRIPTION OF THE DRAWINGS] FIG. 1a is an explanatory diagram of a conventional orientation control method, FIG. 1b is a diagram showing nonuniformity of orientation, and FIG. 2 is an illustration of an orientation control method according to an embodiment of the present invention. The explanatory diagram, FIG. 3, is an explanatory diagram of an orientation control method according to another embodiment of the present invention. 1... Lapping table, 2... Electrode plate, 3
...Protect solid lubricant, 4...Wrapping roller 1, 5...Powder solid lubricant.

Claims (1)

[Scope of Claims] 1. In a liquid crystal cell in which a liquid crystal is sandwiched between a pair of electrode plates, when controlling the orientation of the surface of the electrode plate in contact with the liquid crystal by a rubbing method, a block-shaped solid lubricant is rubbed with a rubbing roller, A method for controlling the alignment of a liquid crystal cell, comprising rubbing an electrode plate with a rubbing roller coated with the solid lubricant. 2. The method for controlling alignment of a liquid crystal cell according to claim 1, wherein the solid lubricant is a block-shaped solid lubricant fixed to the same rubbing table on which the electrode plate is fixed. 3. The liquid crystal cell according to claims 1 to 2, wherein the solid lubricant is selected from boron nitride, molybdenum sulfide, tungsten sulfide, sulfur, talc, soap, etc., and zinc white. Orientation control method. 4. Orientation of a liquid crystal cell according to claim 1, characterized in that after rubbing the electrode plate with a rubbing roller to which a solid lubricant is attached, further rubbing is performed with a rubbing roller to which no solid lubricant is attached. Control method. 5. The method for controlling alignment of a liquid crystal cell according to claim 1, wherein the peripheral sealing material of the liquid crystal cell is a fluorine-based polymer or a low melting point glass.