| 摘要 |
PROBLEM TO BE SOLVED: To provide a condenser microphone unit which is surely shielded by caulking ends of a microphone unit case to press an earth wire pattern of a printed wiring board thereby surely shielding the intrusion of an electromagnetic wave and preventing the mixing of noise in a sound signal. SOLUTION: A diaphragm 20 vibrated by a sound, a fixed electrode 22 opposed to the diaphragm 20, an insulation member, and a circuit board 30 are deposited in a cylindrical unit case 10, the opening end of the unit case 10 is caulked to press the outer circumferential edge of the circuit board 30, and built-in components are fixed in the unit case 10. An earth wire pattern exists at the outer circumferential edge of the circuit board 30, a plurality of parts of the circumferential edge of the earth wire pattern pressed by a caulking part 14 of the unit case are extracted to provide the plurality of parts depressed by the caulking part 14. COPYRIGHT: (C)2006,JPO&NCIPI
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