Patent ID: 8211132

Claim:
An abnormality detecting method for an ultrasonic surgical apparatus including an ultrasonic vibrator which can generate ultrasonic vibrations and a probe which is connected to the ultrasonic vibrator and can transmit the ultrasonic vibrations, the method comprising the steps of: generating a drive signal for driving the ultrasonic vibrator; detecting a voltage signal and a current signal to be supplied to the ultrasonic vibrator based on the drive signal; storing voltage data for a half cycle or one cycle of the voltage signal and current data for a half cycle or one cycle of the current signal; comparing a voltage waveform represented by the voltage data for the half cycle or the one cycle of the voltage signal and a current waveform represented by the current data for the half cycle or the one cycle of the current signal and detecting a waveform distortion of the drive signal to be supplied to the ultrasonic vibrator; and identifying that the probe has an abnormality in accordance with whether or not a difference between the voltage waveform and the current waveform fits in a predetermined range.