| 摘要 |
PURPOSE:To shorten a reverberation time by constituting the titled device of a pair of ultrasonic transmitter-receiver having different antiresonance (resonance) frequencies and disposed electrically in parallel and an oscillation driving circuit generating a frequency corresponding to a part between the antiresonance (resonance) frequencies of the transmitter-receiver. CONSTITUTION:When the two ultrasonic transmitter-receivers T1, T2 having the different antiresonance (resonance) frequencies f1, f2 are driven by the input signal of an intermediate frequency F therebetween, one transmitter-receiver is temporarily forcibly oscillated by the intermediate frequency F, however, after an input signal is impressed, it is freely oscillated by the set antiresonance (resonance) frequency f1 and attenuated. Since the two ultrasonic transmitter- receivers T1, T2 are connected electrically in parallel, an entire synthesized and oscillating waveform is rapidly damped according to a mutual denial and the reverberation time is shortened. |
