| 摘要 |
PROBLEM TO BE SOLVED: To provide a capacitor microphone that is not deteriorated in manufacturing efficiency even if a metallic diaphragm is employed and does not cause a rise in cost. SOLUTION: A diaphragm for constituting an electret capacitor has a vibrating membrane (11) of a primary electrodeposition layer, a diaphragm frame (12) of a secondary electrodeposition layer formed at a peripheral edge on the vibrating membrane, and a reinforcing frame (13), the vibrating membrane, a diaphragm frame, and a reinforcing frame are made of metal different in composition and formed in one body by electrocasting, and the diaphragm frame supports the vibrating membrane against its tension. A metal film is used as the vibrating membrane, so that a microphone is provided which has stable sensitivity and frequency characteristics against temperature and humidity variations. The vibrating membrane, the diaphragm frame, and the reinforcing frame are formed in one body by electrocasting, so that a trouble to tense and stick the metallic vibrating membrane on a diaphragm ring is eliminated and diaphragms having uniform characteristics are easily mass-produced. Further, the reinforcing frame reduces the strain of the vibrating membrane in the frame, so that the strain of the diaphragm frame is hardly transmitted to the whole vibrating membrane. COPYRIGHT: (C)2007,JPO&INPIT
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