JP3084143B2 - screen - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a screen used mainly in a projection television having a liquid crystal display.

[0002]

2. Description of the Related Art In a liquid crystal display device, when linearly polarized light is obtained from non-polarized light source light, a polarizing plate is used to absorb and remove obstructive light components. Since the opaque portions are present in the liquid crystal pixels that generate the light, the efficiency of using the light from the light source is low due to a low aperture ratio of the liquid crystal panel. Liquid crystal display devices have advantages such as small size, light weight, and non-polluting waste products compared with CRT display devices, and are highly evaluated for their future potential. When an image on the screen is projected on the screen, the luminance is insufficient, and it is necessary to view the image in a dark room where external light is blocked. Therefore, while focusing on the fact that the projection light emitted from the liquid crystal display device is linearly polarized light, the outside light that impairs the sharpness of the image projected on the screen is usually unpolarized light, 2. Description of the Related Art There is known a technique of removing a light to clearly view a projected image even in a bright environment. For example, a technique has been proposed in which a light-absorbing polarizing filter oriented in a direction that transmits linearly polarized projection light is mounted on the surface of a screen to reduce the amount of reflection of non-polarized external light. See JP-A-62-266980 and JP-A-64-77085. In addition, a technique has been proposed in which an illumination light source is covered with a light absorption type polarizing filter oriented in a direction orthogonal to a polarizing filter on a screen to sharpen a linearly polarized projected image (Japanese Patent Laid-Open No. 2-267536). Gazette). Here, instead of the polarization filter, a polarization-generating substance is added to a transparent material, stretched, and produced by arranging the polarization-generating substance in the longitudinal direction of the fiber. A polarizing woven fabric obtained by arranging a number of parallel polarizing fibers that transmit light having the same and absorb light having a vibration direction of an electric field perpendicular to the polarizing fiber and weaving the polarizing fibers and the non-polarizing transparent fibers is used. Can be.

[0003]

The projection type screen includes a front screen that uses projection light as reflected light and a rear screen that uses projection light as transmitted light.
In the bright environment, it is not enough to remove the non-polarized external light by the above technology to clarify the projected image of linearly polarized light, and it is necessary to distribute the projected light uniformly within an appropriate viewing angle. is there. In the above polarizing screen, the image viewing angle in a plane perpendicular to the fiber axis can be easily adjusted by optimizing the cross-sectional structure of the fiber, but the image viewing angle in a plane parallel to the fiber axis can be adjusted. It is not easy to do.

[0004] It is an object of the present invention to provide a screen capable of obtaining a clear and uniform brightness projected image within an appropriate viewing angle even in a bright environment.

[0005]

In order to achieve the above object, the screen of the present invention absorbs light having an electric field vibration direction parallel to the fiber axis (hereinafter, the electric field vibration direction is referred to as a polarization direction). And a polarizing fiber having a property of transmitting light having a polarization direction orthogonal to the fiber axis and a non-polarizing transparent fiber, the polarizing fiber and the non-polarizing transparent fiber are arranged so as to intersect each other, A light scattering substance is added to at least one of the fiber and the non-polarized transparent fiber.

[0006]

At least one of the polarizing fiber and the non-polarizing transparent fiber constituting the screen of the present invention contains a light scattering substance, and the light incident on the screen is scattered. Since they have a shape and have a function similar to a cylindrical lens, a wide viewing angle in the horizontal direction and a wide viewing angle in the vertical direction can be obtained. The cross-sectional shape of the polarizing fiber and the non-polarizing transparent fiber may be various shapes such as a circle, an ellipse, and a square, and the concentration of the light diffusing substance added to at least one of the polarizing fiber and the non-polarizing transparent fiber may be changed. Thereby, the viewing angle can be adjusted.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a schematic perspective view of an example of the screen of the present invention. The screen 1 shown in FIG. 1 is woven with a polarizing fiber 2 to which a light scattering substance is added and a non-polarizing transparent fiber 3. The polarizing fiber 2 has a property of transmitting light having a polarization direction D1 orthogonal to the fiber axis and absorbing light having a polarization direction D2 parallel to the fiber axis, and the non-polarizing transparent fiber 3 does not absorb light. Here, by arranging the screen 1 of the present invention such that the polarization direction D1 orthogonal to the fiber axis of the polarizing fiber 2 and the polarization direction of the projection light 4 from a liquid crystal display or the like match, the projection light 4 becomes Since all of them pass through the screen, the brightness of the image is kept high. On the other hand, of the external light 5 having various polarization directions, the light other than the component having the above-mentioned polarization direction D1 is absorbed by the polarizing fibers 2 of the screen 1, and a decrease in contrast due to the external light 5 is prevented. Video is obtained.

FIG. 2 shows a schematic diagram of a polarizing fiber according to the present invention. The polarizing fiber 2 is made of a polyvinyl alcohol, ethylene-vinyl alcohol copolymer (hereinafter, referred to as eval) in which a polarization-expressing substance composed of iodine, dichroic organic dye, or the like has affinity. ) Is added to a fiber made of such a material as described above, and the fiber is stretched in the longitudinal direction L. The presence of the iodine cluster or the dichroic organic dye C in the stretched material in the stretching direction L of the fiber causes the polarizing function to be exhibited. As a result, the polarizing fiber has its fiber axis (longitudinal direction L).
And transmits light having a polarization direction D2 which is parallel to the light, and absorbs light having a polarization direction D2 which is parallel to the light. An example of a method for producing a polarizing fiber to which the light scattering substance S (FIG. 2) is added is as follows. First, the EVAL chip before spinning is heated to a temperature equal to or higher than the melting point, and a light scattering substance such as titanium oxide is kneaded. After spinning, it is immersed in, for example, an aqueous solution of iodine and an alkali iodide. Then, it is stretched 1.5 to 15 times to obtain a polarizing fiber. On the other hand, the polarizing fiber can be obtained by spinning the evar, stretching the film first, and then immersing it in an aqueous solution of iodine and an alkali iodide.
In order to prevent iodine from falling off and suppress light reflection on the fiber surface, the polarizing fiber is immersed in a solution such as triacetyl cellulose after the addition of the above-mentioned iodine and the drawing is completed, so that a film is adhered to the fiber surface. be able to. The polarizing fiber can also be prepared using another polymer instead of Evar, and a dichroic organic dye such as benzene instead of iodine. In addition, as the non-polarized transparent fiber in the present invention, a fiber made of a general-purpose polymer such as nylon or polyester can be used. As the light scattering substance to be added to at least one of the above-mentioned polarizing fiber and non-polarizing transparent fiber, those having an affinity with the constituent material of the fiber to be added, and those which are hardly affected by alteration by the constituent material of the fiber. For example, fine particles of an inorganic oxide such as titanium oxide can be used.

The cross-sectional shapes of the polarizing fiber and the non-polarizing transparent fiber can be variously set such as a circle, an ellipse, and a square. The diameters of the polarizing fiber 1 and the non-polarizing transparent fiber may be set from the viewpoints of weaving properties, flexibility required for winding the screen, resolution of a projected image, prevention of moire based on a periodic arrangement of liquid crystal pixels and fibers, and the like. , Generally 10 to several hundred μ
The range of m is preferred.

[0010] The screen of the present invention may be a front screen or a rear screen. The rear screen can be manufactured by, for example, attaching a screen base having a reflector provided on the front surface of a base material such as a vinyl chloride sheet to one surface of a woven fabric composed of a polarizing fiber and a non-polarizing transparent fiber. .

[0011]

According to the screen of the present invention, a clear and uniform brightness projected image can be obtained within an appropriate viewing angle even in a bright environment.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view of an example of a screen of the present invention.

FIG. 2 is a schematic diagram of a polarizing fiber according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Screen 2 Polarizing fiber 3 Non-polarizing transparent fiber 4 Projection light 5 External light D1 Polarizing direction orthogonal to the fiber axis of the polarizing fiber D2 Polarizing direction parallel to the fiber axis of the polarizing fiber

Claims (1)

(57) [Claims] A polarizing fiber having a property of absorbing light having a vibration direction of an electric field parallel to the fiber axis and transmitting light having a vibration direction of an electric field perpendicular to the fiber axis, and a non-polarizing transparent fiber; A screen, wherein the polarizing fiber and the non-polarizing transparent fiber are arranged so as to intersect each other, and a light scattering substance is added to at least one of the polarizing fiber and the non-polarizing transparent fiber.