GB450502A - Improvements in or relating to the reproduction of recorded sound - Google Patents

Abstract

450,502. Optical sound-reproducing apparatus. RADIO CORPORATION OF AMERICA, 30, Rockefeller Plaza, New York, U.S.A. Nov. 11, 1935, No. 31186. Convention date, Jan. 19. [Class 40 (ii)] An apparatus for reproducing sound from sound records comprises means for producing a plurality of light beams acoustically modulated by the sound record, a light sensitive device provided with a plurality of cathodes and means operable to cause said beams to be applied selectively to the same or to different cathodes of said device according to whether the negative and positive sound impulses are recorded on the same or different tracks or areas. As shown, light from a source 10 after passing through an optical system 12 is modulated by the film 11 and is then transmitted through lenses 13 and is split by lenses 14, 15 into two separate beams, one of which is applied to the stationary reflector 16 and the other to an adjustable reflector 17. When reproducing a record of the kind described in Specification 406,872 in which the negative and positive impulses are separately recorded on tracks spaced from one another, the reflectors 16, 17 are arranged in the full-line position when one of the acoustically modulated light beams is reflected by the reflector 16 on to the cathode 18 of the light sensitive device 19 and the other light beam is reflected by reflector 17 on to the cathode 21 of the device 19. When, however, it is desired to reproduce a record having all the sound components recorded on a single track, the reflector 17 is shifted to the dotted line position when both light beams are reflected on to the cathode 18.