GB389611A - Projection screen - Google Patents

Abstract

389,611. Projection screens. SHIMIZU, T., 57, Komagome Sendagi-cho, Hongo-Ku, Tokio. Jan. 19, 1932, No. 1654. Convention date, Jan. 19, 1931. [Class 97 (i).] In a projection screen for daylight use which consists of a transparent material 1 formed on one face so as to present a large number of small lenticular surfaces 2 and, on the other face, blackened except for small transparent areas at or near the focal points of the lenticular surfaces, the blackened surface is produced by a film of photographic emulsion which is exposed through the screen surface to parallel rays of light and is then subjected to the process of development and chemical reversal. The backing thus produced may be copied by photo-lithographic processes when the front surface of the screen is of the same formation. The lenticular surface may be moulded or may be formed of two gratings of parallel cylindrical rods disposed at right-angles, in which case the back surface of each grating is blackened and provided with a system of parallel transparent lines. When the screen is used for transmitting projection, the back is provided with a translucent or light-diffusing material 6, Fig. 1. For reflecting screens, the focal plane 8 of the lenticular surface is slightly beyond the back of the screen, as shown in Fig. 2, and a coating 7 of silver or white material is applied. In both forms of screen the diffusing or reflecting layer may be in the form of small inclined surfaces.