Electrosurgical generator

Claim 1

A generator for electrosurgery comprising first and second command switches for selecting command status of operation; a command control means coupled to said first and second command switches for preventing simultaneous activation of said first and second command switches; a first mode switch for selecting a mode of operation when the first command switch is activated; a second mode switch for selecting a mode of operation when the second command switch is activated; a mode control means coupled to said first and second mode switches for determining the mode of operation indicated by said first and second command switches and said first and second mode switches, said command control means being coupled to said mode control means by first and second command lines; first, second, third and fourth voltage amplifiers, each said voltage amplifier being coupled to said mode control means so that one of said voltage amplifiers corresponding to the mode of operation indicated by said first and second mode switches and said first and second command switches is activated by said mode control means; a first NAND gate having two inputs, the inputs of said first NAND gate being coupled respectively to the said first and second command lines; high frequency oscillator means and low frequency oscillator means coupled to the output of said first NAND gate so that said high and low frequency oscillator means are activated by said first NAND gate when either command line is activated; a three-input NAND gate, the output of said high frequency oscillator means being coupled to a first input of said three-input NAND gate, the output of said low frequency oscillator means comprising a duty cycle interrupt signal and being coupled to a second input of said three-input NAND gate, variable frequency divider means, the output of said high frequency oscillator means also being coupled to said variable frequency divider means, said variable frequency divider means also being coupled to the output of said mode control means, the output of said variable frequency divider means being coupled to the third input of said three-input NAND gate and comprising a waveform interrupt signal comprised of a high voltage portion and a low voltage portion, the wave-length of said waveform interrupt signal being an integer multiple of the wave-length of the output of said high frequency oscillator means, the ratio of the length of said high voltage portion to the length of said low voltage portion being altered by said variable frequency divider means corresponding to the mode of operation indicated by said first and second mode switches and said first and second command switches; a voltage controlled main amplifier means, the output of said three-input NAND gate being coupled to the input of said voltage controlled main amplifier means and comprising groups of pulses, said voltage controlled main amplifier means including means for selectively increasing the amplitude of a pulse of each said group of pulses from said three-input NAND gate, said voltage controlled main amplifier means being coupled to said first, second, third and fourth voltage amplifiers so that said voltage amplifiers control the output level of said voltage controlled main amplifier means; a DC voltage supply and an isolation transformer means, the output of said voltage controlled main amplifier means being coupled through the primary winding of said isolation transformer means to said DC voltage supply, said isolation transformer means having first and second secondary windings, the side taps of said first secondary winding being coupled through first and second blocking capacitors, respectively, to first and second output terminals for monopolar operation, one side tap of said second secondary winding being coupled through a third blocking capacitor to a third terminal for bipolar operation, the other side tap of said second secondary winding being coupled directly to a fourth output terminal for bipolar operation.