| 摘要 |
PROBLEM TO BE SOLVED: To provide a unidirectional capacitor microphone unit imparted with the same function as that of a rear acoustic terminal hole without forming the rear acoustic terminal hole at a printed circuit board. SOLUTION: An acoustic path 61 is allowed to exhibit the function as the rear acoustic terminal, the acoustic path 61 composed of a thin air layer in which a first gap 39 formed in a portion other than a flat washer 28 and a ground side pattern layer 37 and a second gap 50 formed between a conductive sleeve 27 and a base material exposing surface 49 communicate with each other via a cutout 34 formed on a peripheral edge 33a side of the printed circuit board 33 in caulking and sealing the printed circuit board 33 interposed by the flat washer 28 on a peripheral edge 38 of one side surface 35. Thus, the unidirectional capacitor microphone unit 11 excellent in directional frequency response and having no unwanted substance such as a solder ball can be obtained. COPYRIGHT: (C)2009,JPO&INPIT
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