JPH05333435A - Screen for projection by hologram - Google Patents

Abstract

PURPOSE:To provide the screen which is simple in both construction and production and has wide visual field angles and specific reflection directivity by constituting the screen of a hologram which reflects only the light entering from a specific direction to a specific direction at a specific visual field angle. CONSTITUTION:The hologram photosensitive material is constituted of cellulose acetate butyrate as a base polymer, N vinyl carbazole and phenoxyethyl acrylate as monomers, mercaptobenzothiazole as a radial generating agent, hexaaryl bis-imidazole as an initiator, cyclopentanone bis-diethylaminophenyl methylene as a sensitizer and triethylene glycol diacetate as a plasticizer. This photosensitive material 6 is disposed in an exposing device and is exposed by using an Ar laser 1. One of two luminous fluxes of this time is the light having 20 deg. stereoscopic angle having its vertex on the surface of the photosensitive agent and another is light having 40 deg. stereoscopic angle having its vertex on the surface of the photosensitive agent.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a screen used as a projection surface such as a liquid crystal projector, an overhead projector and a slide projector.

[0002]

2. Description of the Related Art Overhead projectors and slide projectors have long been frequently used in the field of viewing images by a specific large number of people. However, in recent years
With the advent of large TV receivers and the appearance of high-definition high-definition images, large displays are needed.
Liquid crystal projectors, CRTs, plasma displays and the like are mentioned. When a liquid crystal display is used, a screen is required, and the screen is required to be bright and to reflect only specific light. Various devices have been devised to meet such demands,
Some of them are described below.

(A) Rolled aluminum foil method This is a stripped rolled aluminum foil rolled by a two-rolling method in which the rolling direction is positioned horizontally, and has an overall flat and slender unevenness of the aluminum foil sheet. The rough surface is used as the projection surface.

(B) Porous fine particle system This is a rotating body composed of fine wires on one surface of a heat-resistant polyester film, and scratches having a myriad of irregular irregularities in the longitudinal direction are formed in a hairline shape. And a diffuse reflection layer formed by vapor-depositing aluminum or the like on the back surface of the film, and another diffusion reflection layer formed by coating a thin film of the porous fine particle substance diffused in a transparent solution on the scratched surface. The diffusive reflector consisting of is a screen. (JP-A-57-19725)

(C) Bead coating method This is a method in which minute transparent beads are dispersed and coated on the surface of a reflecting layer, and is widely used. In addition, a viewing angle improved product in which a scattering layer is coated on the surface of fine transparent beads has also been proposed (USP 3,637,285). The above is an example of a reflection type, but in addition to this,
For the transmissive type, many screens with the same structure have been proposed.

[0006]

Each of the above-mentioned methods has various problems as described below. Next, each problem will be specifically described.

(A) Rolled Aluminum Foil Method In this method, the viewing range of the screen is relatively narrow, for example, 20 degrees to the left and right of the central axis of the projected light.
Moreover, it is necessary that the rolling direction of the aluminum foil and the horizontal direction of the screen be the same.Furthermore, this screen is a slender, dense and generally extending unevenness that generally occurs in one direction, which is inevitable in the aluminum foil manufacturing process. Since it uses a pattern, it is difficult to adjust its unique reflection directivity,
It is not possible to obtain the optimum angle range for the usage condition.

(B) Porous fine particle method This method can obtain an excellent viewing angle, but scratches are formed on the film surface, the back surface is vacuum-deposited, and the porous fine particle material is applied to a thin layer. Since there are many steps such as forming, there is a drawback that manufacturing is very troublesome.

(C) Bead coating method Although this method is widely used and can obtain a good image, it has a narrower viewing angle than the method of (b) described above and the surrounding environment. When it is bright, there is a drawback that it is difficult to appreciate.

[0010]

The present invention has a simple structure, a simple manufacturing method, a wide viewing angle, a high reflectance, and is used for a projector having a specific reflection directivity. It provides a screen. That is, the present invention relates to a screen used as a projection surface in a liquid crystal projector, an overhead projector, or the like, in which the screen has only a light incident from a specific direction and a specific viewing angle in a specific direction. It is a hologram projection screen characterized in that it is a hologram that is reflected and reflected.

The types of holograms used in the present invention are
There is no particular limitation, and either an embossed type or a Lippmann type may be used, but a Lippmann type having good diffraction efficiency is preferable. Also, the material used for the hologram may be any material as long as it can realize a good hologram, but considering the environment resistance, the material using the photopolymer is more preferable than the dichromated gelatin. preferable.

The viewing angle of the screen of the present invention can be freely controlled by the angle formed by the two light beams during the exposure of the hologram serving as the screen, and it is possible to realize a very bright screen with a wide viewing angle. . Furthermore, light incident from directions other than the time of exposure is not reflected on the screen, and it is possible to exclude light in directions other than the necessary direction.

Examples are shown below, but the materials and manufacturing methods used here are not particularly limited.

Example 1 The following were used as hologram photosensitive materials for screens. Cellulose acetate butyrate as a base polymer, N vinylcarbazole and phenoxyethyl acrylate as a monomer, mercaptobenzothiazole as a radical generator, hexaallyl bisimidazole as an initiator, and cyclopentanone bisdiethylaminophenyl as a sensitizer. Methylene, triethylene glycol diacetate as a plasticizer. The respective compounding ratios are shown below. Materials Weight ratio (%) Cellulose acetate butyrate 53.00 N vinylcarbazole 15.05 Phenoxyethyl acrylate 21.97 Mercaptobenzothiazole 1.79 Hexaallyl bisimidazole 1.03 Cyclopentanone bisdiethylaminophenylmethylene 0.16 Triethylene Glycol diacetate 7.00

The above materials were dissolved in a solvent and applied on a PET film having a thickness of 100 μm to obtain a photosensitive layer having a thickness of about 25 μm. The manufactured light-sensitive material was placed in an exposure device as shown in FIG. 1 and exposed using an Ar laser. At this time 2
One of the light fluxes is a light having a solid angle of 20 ° with the vertex on the surface of the photosensitizer, and the other is a light having a solid angle of 40 ° with the vertex on the surface of the photosensitizer. It is a bright light. The exposure apparatus performed the exposure while gradually moving the photosensitive material, and repeated the exposure over an area of 1 m in length and 2 m in width.

After exposing all the areas, the whole surface was exposed by using a low pressure mercury lamp to polymerize all the monomers remaining in the photosensitive material. When a slide photograph was projected with a projector using the manufactured screen, a reflectance of 80% or more was obtained. In addition, since the manufactured screen has the property of reflecting only the light coming from the direction of the slide projector, it is less affected by ambient light and can be viewed well even in bright surroundings. It was

[0016]

According to the present invention, a screen having a simple structure, a simple manufacturing method, a wide viewing angle, a high reflectance, and a projector having a specific reflection directivity is manufactured. I was able to.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a hologram exposure apparatus for a screen used in a first embodiment.

[Explanation of symbols]

 1: Ar laser 2 Half mirror 3 Mirror 4 Beam expander 5 Photosensitive material feed roller 6 Photosensitive material

Claims (1)

[Claims] 1. A screen used for a projection such as a liquid crystal projector or an overhead projector, which is a hologram, wherein the screen is a hologram.