| 摘要 |
A diaphragm for sensing sound pressure faces a back plate including a plate portion and a fixed electrode film to form a capacitance type acoustic sensor. The back plate is opened with acoustic holes for passing vibration, and is arranged with a plurality of stoppers in a projecting manner on a surface facing the diaphragm. The stopper arranged in an outer peripheral area of the back plate has a small diameter, and the stopper arranged in an internal area has a large diameter. Thus, sticking of the diaphragm is prevented, and the diaphragm is less likely to break by impact when the sensor is dropped.
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