Improvements in and relating to vibration responsive apparatus or microphones

摘要

332,723. Holman, H. E., and Clark, H. A. M. July 6,1929. Diaphragms.-In a microphone, the surface of the diaphragm in immediate contact with the carbon granules forming the variable resistance member is roughened bv a coating of non-metallic granular material, the protuberances of which are mutually united to one another and to the diaphragm. A substantially rigid or resonant diaphragm of mica or metal is coated with a film of cement, and a thin layer of carbon or carborundum granules rolled into firm contact with the film. In a modification, sand or ground glass may be substituted for the carbon.