GB444824A - Improvements relating to projection screens for cinematographs - Google Patents

Abstract

444,824. Projection screens. TURNER, E. G., and WITCHALLS, F. W., 43, Higham Street, Walthamstow, London. Oct. 2, 1934, Nos. 28202/34, 13342/35, and 13655/35. [Class 97 (i)] Perforated metal screens are built up from sheets secured together at their edges in such manner that there is no material obstruction of the perforations, and little or no area of contact between the parts of the sheets providing the display surface and any member used to support the sheets ; lack of uniformity in the reflecting qualities of the coated screen surface, and reduction of the area available for sound transmission, are thus minimized. As shown in Fig. 3, the sheets A have return edges A<1> secured together by bolts and clamping strips B. The strips B are chamfered so as to have little or no surface in contact with the main portions of the sheets. A narrow filling strip C may be fitted to render the front surface of the screen substantially continuous. The structure may be mounted on a main frame having tie rods. Fig. 4 shows a modification in which the edges of the sheets A are secured by staples to wood or other supports D having front faces forming a V to reduce the area of contact; the edges of the sheets may be butted together. According to the first Provisional Specification, the sheets may be bent along a line of perforations to form the return edges, the return edges may be welded together, and reinforcing members of T-section, or of sheet metal bent to such section, may be provided at the joints. According to the second Provisional Specification, the reinforcing members may be of U- or L-section, and the joints may be filled. with plastic material containing white lead, with a welded strip, or with a soft metal strip caulked or hammered flush with the screen surface.