High-frequency power supply device and electrosurgical device

An electrosurgical device comprising:

• a treatment tool for performing a treatment on a biological tissue;
• and
• a high-frequency power supply device which outputs a high-frequency voltage on the basis of an instruction signal outputted from an operation instruction unit capable of outputting the instruction signal for causing the output of a high-frequency current to the biological tissue, and which outputs the high-frequency current based on the high-frequency voltage via the treatment tool,
• the electrosurgical device further comprising:
• a phase detection unit for detecting respective phases of the high-frequency voltage and the high-frequency current outputted from the high-frequency power supply device;
• an impedance calculation unit for calculating the impedance of the biological tissue on the basis of the voltage magnitude of the high-frequency voltage outputted from the high-frequency power supply device and the current magnitude of the high-frequency current outputted from the high-frequency power supply device;
• a phase difference calculation unit for calculating the phase difference between the high-frequency voltage and the high-frequency current outputted from the high-frequency power supply device on the basis of the respective phases detected by the phase detection unit;
• and
• a control unit for performing a control on the high-frequency power supply device to output a high-frequency voltage and a high-frequency current having a predetermined waveform on the basis of at least one of the impedance and the phase difference and the output state of the instruction signal, wherein
• immediately after the output of the instruction signal, the control unit further performs a first control on the high-frequency power supply device to output a high-frequency voltage and a high-frequency current having a first waveform, and when the instruction signal continues to be outputted, and upon detection that the phase difference has increased from 0°, the control unit further performs, subsequent to the first control, a second control on the high-frequency power supply device to output a high-frequency voltage and a high-frequency current having a second waveform with a lower crest factor than that of the first waveform.