Title:
【発明の名称】ESU漏れ電流制御のための装置及び関連の方法
Document Type and Number:
Japanese Patent JP2671965
Kind Code:
B2
Abstract:
Apparatus and method find leakage due to tissue load or transients and has active and return electrodes for RF energy sensed by transformers for a circuit that finds leakage at more than two thousand times per second or a frequency dependent on the phase shift between voltage and current. Software and feedback manage Vrms to reduce the voltage or increase the crest factor, which is Vrms divided by peak voltage, by pulse width modulation of the RF drive. Voltage and current phase shift changes, angle theta , are compared to a threshold, and when greater, the frequency at which the differences between the active and return current signals are examined is increased. The differences between the active and return currents are examined and when greater than maximum leakage while in coagulation mode, the RF drive pulse width is reduced to maintain voltage wave peaks at a preset value and reduce Vrms thereby reducing leakage to the allowable maximum. Reducing the duty cycle or the pulse width of the output wave increases the crest factor. When the differences between active and return currents are greater than a maximum for leakage while in cut or bipolar mode, the Vrms is reduced to limit leakage to a maximum level. When the phase angle theta is less than a threshold, the frequency with which leakage is examined is reduced.
Inventors:
Chrisek, Michael Es
William G. Patterson
William G. Patterson
Application Number:
JP52037094A
Publication Date:
November 05, 1997
Filing Date:
April 26, 1994
Export Citation:
Assignee:
Valley Love Incorporated
International Classes:
A61B18/12; (IPC1-7): A61B17/39
Other References:
【文献】米国特許3897787(US,A)
Attorney, Agent or Firm:
Kyozo Yuasa (5 people outside)