| 摘要 |
PROBLEM TO BE SOLVED: To ensure electromagnetic shield on the rear surface side of a unit case in a condenser microphone unit for which an FET (impedance converter) is built inside the unit case, to eliminate the leakage of sound waves, and to apply almost uniform and stable internal stress to built-in components. SOLUTION: The condenser microphone unit 1A is constituted so that an acoustoelectric converter 3 composed by oppositely disposing a diaphragm 31 and a fixed pole 33 through a spacer member 35 and the FET 4 are housed inside a unit case 2 provided with a front acoustic terminal hole 21 on the front end face side and opened on the rear end face side, a circuit board 5 is disposed at an opening part 22 on the rear end face side of the unit case 2, and the built-in components 3 and 5 are fixed inside the unit case 2 by caulking of the end edge 221 of the opening part 22. Between the rear surface side of the acoustoelectric converter 3 and the circuit board 5, an elastic disk-shape gel-like ferrite sheet 8 whose outer diameter is roughly equal to the inner diameter of the unit case 2 is clamped. COPYRIGHT: (C)2011,JPO&INPIT |
