GB487318A - Improvements in or relating to scanning devices for television and like systems - Google Patents

Abstract

487,318. Television. SCOPHONY, Ltd., and LEE, H. W. Nov. 13, 1936, No. 31010. [Class 40 (iii)] A fixedoptical system is associated with a rotating scanner, such as a mirror or lens drum, in such a way that light, after initial reflection from the scanner passes through the optical system and is returned to the scanner so that the final deflection is different from that normally obtained. The distances from the drum of the points about which the initially reflected and finally emergent rays respectively describe angular movements are approximately equal. A beam of light incident on mirrors 3, 4 would normally be deflected through the angle between extreme rays 5, 6. After passing through lens 7, prism 9 and lens 8 and reflection from mirrors 10, 11, the ray rotates through an angle whose vertex is approximately on mirrors 10, 11. This angle plus the normal obtainable angle gives the final angle of scan, its value depending on the magnification of the lens system. An inverting optical system reduces the angle of scan, Fig. 3 (not shown). For use with a lens drum, as described in Specification 443,393, Fig. 4 (not shown), reflection is used three times to bring the rays back to the drum for the second scanning operation. Various optical systems are described.