GB473268A - Improvements in or relating to sound-film reproducing apparatus - Google Patents

Abstract

473,268. Optical sound - reproducing apparatus. ARNDT, M. Feb. 4, 1936, Nos. 3293 and 3295. Convention dates, March 18, 1935 and June 27, 1935. [Class 40 (ii)] [Also in Group XL] Relates to apparatus for reproducing sounds from films or strip record carriers bearing a number of parallel sound records in which a lamellar barrier layer cell is provided behind each record, the surface of each cell being disposed at right angles to the surface of the film with its edge normal to the direction of movement of the film and the boundary surface of the counter electrode and the cuprous oxide or semi-conductive layer of the cell being illuminated by light directed upon it from the far side of the film or record carrier. According to the invention, the illumination of the film or record carrier, which illumination may take the form of an extended band of light or a large spot of light, extends over all the cells and their counter electrodes simultaneously and a switch, preferably of the rotary type, is provided which connects to the amplifier only the particular cell corresponding to the sound record that is required to be reproduced. The transfer from one sound record to the next is preferably effected mechanically or electrically in an automatic manner and during such transfer there may be simultaneously a reversal of the direction of movement of the film or record carrier. The cells may be arranged in alignment and in the same plane or stepwise and in different planes. Specification 286,768, [Class 40 (ii)], is referred to. The Specification as open to inspection under Sect. 91 comprises also an arrangement in which the counter electrode, which is preferably smaller than the cell electrode, extends up to or even beyond the edge of the cell electrode and in which the point of convergence of the impinging light is made to fall a short distance in front of or in the record carrier. In order to avoid unpleasant crackling, if switching over from one cell to the next is effected by hand, the transitions between the several positions of the switch can be bridged by resistances and condensers. The layer of metallic oxide in the cell is preferably made very thin and has a maximum thickness of from 0À2 to 0À3 mm. The reduction of this layer to the desired thickness is preferably effected by chemical means, such as by etching with potassium cyanide or acids. The efficiency of the cell may be improved by applying an adjustable auxiliary voltage thereto. This subject-matter does not appear in the Specification as accepted.