Control device for a high frequency surgical apparatus

Claim 1

A high frequency surgical apparatus including a neutral electrode adapted to be affixed to a patient's body, an active electrode adapted for surgical treatment of the patient's body, a high frequency current generator connected to the active and neutral electrodes, and a control circuit adapted to detect a high frequency voltage relative to the neutral electrode during treatment and to control the high frequency current generator in response thereto, comprising: (a) a control electrode adapted to be affixed to the patient's body at a large distance from said active electrode; (b) squaring means connected to said control electrode for squaring a voltage signal detected by said control electrode; (c) integrating means for integrating over time the squared voltage signal; (d) comparator means having a first input and a second input, said first input connected to an output of said integrating means; (e) a variable reference voltage source connected to said second input, for providing a predetermined reference voltage to said second input; and (f) switch means actuated by said comparator means for turning off said high frequency current generator, when the output voltage of said integrating means equals or exceeds said predetermined reference voltage.