| 摘要 |
PURPOSE:To improve the attenuation dependent upon directions by providing a resonance body consisting of a hollow case which has plural entrances for ultrasonic waves on the circumference. CONSTITUTION:Ultrasonic wave oscillation part 2 excited by ultrasonic wave oscillator circuit 1 radiates ultrasonic waves. Since an ultrasonic wave collector is constituted as resonance body 3 which has microphone 6 internally and consists of a hollow case provided with plural holes 4 on the circumference, the reflection wave, the refracted wave, etc., of the ultrasonic wave are propagated to the inside of the resonance body from plural holes 4 on the circumference of the hollow case and are resonated to the hollow case even if the sound collector above is placed outside the range of the effective angle of ultrasonic wave oscillator 2. Then, a strong vibration is given to microphone 6, so that an efficient ultrasonic wave sound collection can be performed. |
