Optical: systems and elements – Projection screen – Embedded particles
Patent
1993-11-22
1994-11-01
Wintercorn, Richard A.
Optical: systems and elements
Projection screen
Embedded particles
264 19, 359459, G03B 2156
Patent
active
053611632
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to projection screens, specifically a reflection type screen for projecting thereon a moving picture such as a motion picture, to a production process thereof, and to a production apparatus thereof.
BACKGROUND ART
A screen used for projection of a slide or OHP, or, for projection of a movie or video is generally a lamination of a dark backing sheet and a white polyvinyl chloride (PVC) film. Conventional screens have low reflectivities and therefore dark projected images, so that the projected images cannot be watched except in a dark room. In addition, the conventional screens have low diffusing powers, so that the projected images cannot be watched except within a limited range of angle to the screen surface.
There is a screen in which glass beads are bonded to the PVC film to enhance the reflectivity and the diffusing power. Such a screen, however, has unevenness on its surface and is easily contaminated. Therefore, the glass beads are readily scraped off when the contaminants are wiped off from the surface thereof, which is a defect of such a screen. If such a screen is used as a screen of wind-up type, the glass beads will gradually drop off while the screen is wound and unwound many times, which is also a problem.
There is proposed ( in Japanese Laid-open Utility Model Publication No. Sho 64-40835) a screen comprising the dark backing sheet and the white PVC film as described above, in which a metallized layer is provided as a reflection layer on the white PVC film, in which a translucent PVC film containing a pearl pigment is laminated thereon, and in which a specific emboss is provided on the outer surface thereof.
A screen having a reflection layer of metal has a too high light reflectivity and too many components of specular reflection (where incidence angle =reflection angle), so that a halation is caused to present a dull image projected. In addition, while a plastic sheet (mainly a polyester sheet) must be used with a strong adhesivity to the metallized layer in order to form the metallized layer as a reflection layer, there is a defect in that such a plastic sheet is likely to have creases. In other words, there remain folds caused upon transfer or wind-up of the screen, and the high reflectivity makes the folds outstanding. These problems are serious if a screen should be of a big picture plane, for example, of 100 inches.
DISCLOSURE OF THE INVENTION
It is a first object of the present invention to provide a reflection type screen having a diffusing power and a reflectivity suitable for a projection screen, which is free of creases and easy in handling.
It is a second object of the present invention to provide a reflection type projection screen which has high contrast even in a bright place to secure a clear image while restraining disturbance of stray lights.
It is a third object of the present invention to provide a reflection type projection screen which, solving the problems as described, provides a beautiful image and can enhance a sound effect.
It is a fourth object of the present invention to provide a reflection type projection screen which can always assure a clear image, solving the above-mentioned problems.
It is a fifth object of the present invention to provide a process for producing a reflection type projection screen having desired optical properties, which is advantageous in productivity in an industrial application.
It is a sixth object of the present invention to provide a process for readily producing a reflection type projection screen having an emboss and light absorbing stripes.
(1) A first feature of the present invention is a reflection type projection screen provided in order with a light absorbing layer of a dark plastic sheet, a fibrous sheet of glass fibers, a base material sheet of a white, opaque, flexible plastic, and a light diffusing layer of a translucent, flexible plastic into which a lustrous pigment or calcite powder is incorporated, wherein a convexo-concave emboss is formed on the outer surface of th
REFERENCES:
patent: 2928131 (1960-03-01), Mahler
patent: 4140369 (1979-02-01), Howland
patent: 4165153 (1979-08-01), Land
patent: 4354738 (1982-10-01), Forehand et al.
Hanamoto Keiji
Matsuda Noriaki
Dai Nippon Printing Co. Ltd.
Wintercorn Richard A.
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