GB349469A - Improvements in or relating to methods and apparatus for recording electrical variations for example for sound recording - Google Patents

Abstract

349,469. Recording by photographic means. PRISNER, S. and WENDER, E., 1, Mowbray Road, Kilburn, London. Feb. 25, 1930, No. 6317. [Class 106 (iv).] A method of recording electrical variations, particularly intended for recording sound, consists in mechanically acting, by means of a vibrating stylus, upon a photographic film or like surface, whereby the action of the stylus upon the sensitive material produces a record resembling one obtainable by the action of light. An electromagnetic device similar to an ordinary sound-recorder may be used, the cutting tool being replaced by a stylus which tapers to a small area having its greater dimension transverse to the film. The stylus vibrates in contact with the film in a direction at right angles to the direction of travel of the film, and so produces an effect which after development of the film appears as a trace resembling a " variable area " record made by the usual optical method. Alternatively, the recording stylus may be tapered to a rounded point, and arranged to act upon the record surface by variations of pressure thereon, so as to produce a record trace of varying intensity. Both methods of recording may be used in combination. The invention may also be applied to making records on discs, having the trace in spiral form. Reproduction from records made in accordance with the invention may be effected by means of apparatus ordinarily used with photographic records.