| 摘要 |
PROBLEM TO BE SOLVED: To provide a speaker which maintains constant sound pressure, regardless of the humidity by reducing the influence due to the humidity on the sound pressure, without increasing the man-hours for processing. SOLUTION: A control unit 40 performs control to complement a bias voltage, applied to a diaphragm 14 when the insulation resistance between an electrode plate 11 and an electrode plate 12, and the diaphragm 14 decreases, as the humidity increases. Namely, the control unit 40 keeps the bias voltage applied to the diaphragm 14 constant, even if the insulation resistance between the electrode plate 11 and electrode plate 12, and the diaphragm 14 varies due to the change in the humidity around the speaker 10. Consequently, variations in the sound pressure of a sound generated by the speaker 10 are reduced, even if the humidity varies. COPYRIGHT: (C)2008,JPO&INPIT
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