GB250692A - Improvements in and relating to diaphragms for loud speakers, telephones, gramophones, phonographs, or any sound reproducing machine - Google Patents

Abstract

250,692. Foweraker, A. M. Jan. 21, 1925. Diaphragms.-A multiple diaphragm for a telephone, loud-speaker, gramophone, or other acoustical instrument comprises a number of superimposed members or surfaces of Y-shaped vertical section fastened together so as to form a continuous surface of spiral or similar transverse section, the convolutions of which include a continuous expanding cavity between them, and are fastened together at their apices so as to vibrate in unison, the cavity providing an impedance. It may be used with or without a horn or ear-piece. The diaphragm may be formed by fastening together along a radial cut two or more circular discs of paper &c. and then twisting the discs about their common centre until they take up the form shown. The apices are glued together and the edges are spaced apart and secured by paper strips i, some of which may be fastened to a circular frame h. The system may be mounted on a shallow cone or flat diaphragm g, and the apex reinforced by a wooden or papier-mÔchÚ plug i projecting through the diaphragm g to receive the applied vibrations. The transverse section of the, multiple diaphragm may be in the form of an open figure approximating to that of a spiral and made up of a succession of straight or curved lines connected together. According to the Provisional Specification the multiple diaphragm may be made up of a number of curved or conical surfaces having cavities between them, the surfaces being of successively diminishing curvature or angle of expansion, and the transverse section being of any regular form, such as circular, curvilinear, or multilateral, or a combination of curvilinear and multilateral.