PROBLEM TO BE SOLVED: To provide an active silencer in which a response characteristic is improved.
SOLUTION: A speaker section is constituted of: a diaphragm 110 for generating sound, a voice coil 120 for driving the diaphragm; and a distance sensor 130 for detecting motion of the diaphragm. Reflection light which is generated from a light emitting diode (LED) 132 and reflected by the diaphragm 110 is detected by a photo-transistor 134, and motion of the diaphragm 110 is detected by measuring a distance from the diaphragm. In a circuit of Fig (b), a signal having a phase opposite to noise is generated from the noise detected by a microphone 140 by an anti-phase generation section 150. Difference between the signal of the anti-phase from the anti-phase generation section 150, and the distance signal of the speaker from the distance sensor 130 is calculated by a difference amplifier 170, and input to a PID control section 160. The difference (deviation e) indicates delay of motion of the speaker. Feedback control is performed in a direction canceling the difference by the PID control section 160.
- 国立大学法人九州工業大学 イノベーション推進機構 グローバル産学連携センター 知的財産部門
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