GB360942A - Improvements in or relating to television and like apparatus - Google Patents

Abstract

360,942. Television transmitters. BAIRD, J. L. and TELEVISION, Ltd., 133, Long Acre, London. Aug. 6, 1930, Nos. 23608/30 and 11354/31. [Class 40 (iii).] Relates to television transmitters employing a mirror drum simultaneously scanning an object in a plurality of contiguous zones. According to one feature of the invention, a lens 19, Fig. 3, is placed at a distance equal to its focal length from the mirrors 14 so that should the distance between the object 10 and the drum 13 alter, no alteration need be made in the distance between the screen 17 and the drum 13, or in the size and the distance apart of the apertures 18 associated with the cells 15. The lens 19 may be placed between the drum and the screen. The object 10 may be floodlighted or, according to another feature of the invention, spots 20, 21, 22 or strips 25 of light may illuminate the elemental areas being scanned by the drum 13. This may be achieved by using a second drum rotating synchronously with the first to reflect light on to the picture, or, as illustrated, the scanning drum may be employed in conjunction with a suitably shaped light source 24. According to a further feature of the invention, the object may be scanned by a plurality of mirror drums, preferably synchronously rotated, each associated with a lens, a cell, and an apertured screen. A practical embodiment of apparatus according to the invention comprises a mirror drum 13, Fig. 4, partially enclosed by a shield 29 ; a lens 19 mounted in an adjustable casing 30 containing the apertured screen 17 and the cells 15; and a mask 34 limiting the solid angle over which exploration is effected. The individual mirrors may be adjustably mounted between suitable springs and three screws, Figs. 6 and 7 (not shown). According to the first Provisional Specification the object may be spot-lighted by a rotating disc. Specification 348,638 is referred to.