JPH02264905A - Method of manufacturing optical compensation plate - Google Patents

Abstract

PURPOSE:To easily produce the optical compensation plate by using a high-polymer film which forms a refractive index anisotropic body exhibiting positive double refractiveness when stretched and biaxially stretching this film. CONSTITUTION:The molecules of the high-polymer film, such as polycarbonate film or polyethylene film, which forms the refractive index anisotropic body exhibiting the positive double refractiveness when stretched elongate in the main chain direction and since the groups, such as benzene rings, to increase the refractive index exist in the main chains, the refractive index in the main chain direction is larger than the refractive index in the direction perpendicular thereto if the main chains are uniformed in the stretching direction by stretching the film. The optically anisotropic body 13 exhibiting the positive double refractiveness in the stretching direction is, therefore, obtd. if the film is stretched. Such high-polymer film 11 is consequently stretched in an arrow direction 12 and is then stretched in the direction perpendicular to the direction 12. The refractive index anisotropic body 13 is then increased in the refractive index in the stretching direction by the 2nd stretching so as to have the refractive index of about the same degree as the refractive index in the direction perpendicular to the stretching direction. The optically negative uniaxial optically anisotropic body is eventually formed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for manufacturing an optical compensator that widens the viewing angle range of a liquid crystal electro-optical element.

[Prior Art] A method of expanding the viewing angle range of a liquid crystal electro-optical element p that uses a voltage-controlled birefringence effect and is made by sandwiching a homeotropically aligned liquid crystal between two electrode substrates. As proposed in Japanese Patent Application No. 62-210423, there is a method of using an optically anisotropic body having optically negative uniaxiality as a viewing angle compensation plate.

The method of manufacturing the viewing angle compensation plate disclosed in Japanese Patent Application No. 62-210423 is as follows.

5tJRLY from Dupont de Nemours
The thermoplastic resin Puylum sold under the product name N.
Place it between two glass plates and apply uniform pressure to each plate in this state. In this method, as shown in FIG. 2, an assembly consisting of a film 23 and plates 21 and 22 is placed in a plastic bag 24, the inside of the bag is evacuated, the bag is sealed with heat, and a uniform pressure equal to atmospheric pressure is applied to each bag. Pour onto a plate. The bag containing the assembly is then heated in an oven to change the thermoplastic material from a glassy state to an isotropic state, after which the bag is removed and opened.

The material is then allowed to cool and shrink. Since the material then contracts only in one direction perpendicular to the plane of the plate, a negative uniaxial optical anisotropy containing the extraordinary refractive index of the medium in a direction subperpendicular to the layer is obtained.

[Problems to be Solved by the Invention] However, in the conventional method for manufacturing an optical compensation plate, the process of evacuating and heat-sealing the bag containing the assembly is cumbersome;
The problem was that it was not suitable for mass production.

The present invention is intended to solve these problems, and its purpose is to provide a simple method for manufacturing an optical compensation plate.

[Means for Solving the Problems] The method for producing an optical compensator of the present invention is characterized by biaxially stretching a polymer film that forms a refractive index anisotropic body exhibiting positive birefringence upon stretching. shall be.

[Function] Polymer films such as bocker carbonate film and Bois ethylene film that form refractive index anisotropic bodies exhibiting positive birefringence by normal stretching have molecules extending in the direction of the main chain, and the refraction of benzene rings, etc. Since groups that increase the index are also present in the main chain, when the main chains are aligned in the stretching direction by stretching, the refractive index in the main chain direction becomes larger than the refractive index in the direction perpendicular to the main chain. Therefore, when stretched, it becomes an optically anisotropic body that exhibits positive birefringence in the stretching direction. In the method for producing an optical compensator of the present invention, by biaxially stretching such a polymer film, the refractive index in the stretching direction is made larger than the refractive index in the direction perpendicular to the stretching direction. An optically negative refractive index anisotropic body can be formed.

Hereinafter, the details of the present invention will be shown by examples.

[Example] FIGS. 1(a) to 1(b) are diagrams showing a method for manufacturing an optical compensator of the present invention. The manufacturing method is first shown in Figure 1(a).
As shown in the figure, a transparent polymer film 11 was heated to 170'C and stretched at a speed of 0.5 mm/sec in the direction indicated by 12 in the figure.

As the polymer film, a polycarbonate film manufactured by Sumitomo Chemical Co., Ltd. and having a thickness of 110 μm was used here. When the polycarbonate was stretched, it formed a refractive index anisotropic body 13 exhibiting positive birefringence in the stretching direction.

Next, as shown in FIG. 1(b), this polymer film was stretched at a rate of 0.5 mm/sec in a direction perpendicular to the initial stretching direction while being heated to 170°C. In the refractive index anisotropic body 3 of the boso carbonate film, the refractive index in the stretching direction increased by the second stretching, and the refractive index became approximately the same as that in the direction perpendicular to the stretching direction. Therefore, by stretching twice, the polycarbonate film became a negative uniaxial optically anisotropic body containing the extraordinary refractive index of the medium in the direction perpendicular to the stretching direction (that is, the direction perpendicular to the film surface).

The optical compensator thus obtained has a refractive index in the direction perpendicular to the film surface N5e=1.5832, a refractive index in the direction horizontal to the film surface N1o=1.5953, and N2o=1.5.
It was 948.

[Effects of the Invention] As described above, according to the present invention, a uniform optical compensator plate can be manufactured by a method simpler than the conventional method.

FIGS. 1(a) to 1(b) are diagrams showing a method for manufacturing the optical compensator of the present invention.

FIG. 2 is a diagram showing a conventional method of manufacturing an optical compensator.

11...Polymer film 12...Stretching direction 13...Refractive index anisotropic body 21, 22... plate 23...Thermoplastic film 24・・・Plastic bag that's all Applicant: Seiko Epson Corporation Agent: Patent attorney: Kisanbe Meiki (1 other person)

[Brief explanation of drawings]

figure

Claims (1)

[Claims] A method for producing an optical compensator, which comprises biaxially stretching a polymer film that forms a refractive index anisotropic body exhibiting positive birefringence upon stretching.