| 摘要 |
The device has a sensor unit (5) to detect a resonance vibration of an acoustic signal generator (1) e.g. piezoelectric plate. A modulation unit modulates amplitude and frequency of a carrier wave of the generator. The modulated frequency of the carrier wave corresponds to the resonance frequency of the signal generator. The resonant and stationary phases of the signal generator are changed with the frequency of a modulation wave. |
