GB307734A - Electrostatic acoustic device - Google Patents

Abstract

307,734. Newcombe - Hawley, Inc., (Assignees of Kyle, C.). March 12, 1928, [Convention date]. Condenser telephones diaphragms; loudspeakers.-Relates to electrostatic transmitters or reproducers of the type comprising a rigid perforated metallic plate, a thin flexible metallic plate and an intermediate flexible diedectric diaphragm and consists in inserting a soft or yielding buffer material between the diaphragm and rigid plate so as to allow of the use of hard materials such as paper, celluloid, mica &c. for the diaphragm. The buffer material may comprise a thin rubber coating, granulated rubber, soft gelatine substance &c. In the construction shown, a rigid perforated plate A, provided with an annuar rim 2, serves as a support for buffer material B, a flexible diaphragm C and a flexible metallic plate D. In assembling the device, a thin coating of rubber B is first applied to one side of the diaphragm, the coating being preferably partially vulcanized and the surface treated with soapstone &c. The diaphragm is then strertched over the plate A and clamped by the band 3, after which the flexible metallic plate D is formed on the exterior surface of the diaphragm by pasting gold leaf &c. thereon applying a thin coating of metal, or by metallic spray, electrolytic deposition, plating, &c. Alternatively, the buffer may be formed by applying a thin coating of rubber cement to the inner face of the diaphragm and then sprinkling on a thin t coating of granulated rubber.