| 摘要 |
PROBLEM TO BE SOLVED: To provide a fixed electrode unit reduced in a stray capacity of a microphone, having a structure which can be incorporated in a unit case and is applicable to a large-diameter unit having many holes forming openings of a fixed electrode as a constituent member of an electret micrphone unit having respective members disposed by a pressing force by a folded-back portion of the unit case. SOLUTION: The fixed electrode unit 10 has the fixed electrode 15 having an electret material 31 stuck on the surface opposed to a diaphragm 13, an insulating ring 32 having an opening that the fixed electrode enters and defining a radial size in the unit case to fix the fixed electrode at a predetermined position, and a fixing means of uniting the fixed electrode and an insulating ring so that the fixed electrode entering the opening portion of the insulating ring forms a plane at the same height as the insulating ring. Further, the fixed electrode has its external diameter D1 smaller than the internal diameter D2 of a diaphragm holder 12. COPYRIGHT: (C)2008,JPO&INPIT
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