| 摘要 |
PURPOSE:To enable a constantly stable and excellent ultrasonic therapy with effects of high frequency signals on ultrasonic signals avoided by applying ultrasonic signals to an ultrasonic oscillator and output signals of modulation means to the ultrasonic transmitter. CONSTITUTION:Ultrasonic signals emitted from an ultrasonic signal generator 9 are supplied by an amplifier 8: voltage of output signals of the amplifier 8 is detected by a voltage detector 10, and current of the output signals by a current detector 11; and phases of detected voltage and current are compared by a phase comparator 12. In this case, high frequency signals supplied to the handpiece 1 penetrate the voltage detector 10 and the current detector 11: the penetrating high frequency signals come out of a vicinity of the zero-cross point of ultrasonic signal voltage by the modulation effect of a window comparator 23 and a gate circuit 24, so that only phases of ultrasonic signals are precisely detected. This way of precise detection and then feedback rejects malfunction doe to high-frequency signals and enables a constantly stable and excellent ultrasonic therapy. |
