Electro-surgical apparatus

Claim 2

Electro-surgical apparatus comprising: a utilization circuit including a conductive surgical instrument, said utilization circuit being susceptive of alternatively constituting relatively low and high impedance electrical loads as the area of the interface between said instrument and tissue varies between large and small values under differing conditions of use, a source of high frequency electrical signals, a transistorized power amplifier having an input circuit responsive to said high frequency electrical signals and an output circuit, and a transformer having a core, a secondary winding wound on said core and connected to said utilization circuit, and a primary winding wound on said core and responsive to said output circuit of said transistorized amplifier, said transformer being a step-up transformer in which the number of turns of the secondary winding substantially exceeds the number of turns of the primary winding, said transformer being characterized by having said windings tightly coupled and by having said core fabricated of high magnetic permeability material for reflecting back to said primary winding the impedance of said secondary winding and utilization circuit, thereby enabling said transistor amplifier to supply useful current to said instrument when said utilization circuit is in its low load impedance condition without producing damaging currents in said amplifier when said utilization circuit is in its high load impedance condition.

Claim 3

The apparatus of claim 1 wherein the magnetic permeability of said core is approximately 2,000 and wherein said core is configured in the form of a hollow cylinder having closed ends internally connected by a rod about which said primary and secondary windings are wound.

Claim 4

The apparatus of claim 2 wherein said high frequency signal source includes a transistorized high frequency pulse generator and a differentiating circuit for converting output pulses from said generator to signals having a high ratio of peak current to average current.

Claim 5

The apparatus of claim 3 further including: a transistor switch connected between said pulse generator and a source of supply potential, and a low frequency oscillator having an output circuit connected to control said transistor switch for alternately de-energizing and energizing said pulse generator to enable successive trains of high frequency pulses to be input to said differentiating circuit during successive oscillations of said low frequency oscillator, thereby facilitating the application of a coagulating current level to said instrument.

Claim 6

The apparatus of claim 4 further including selectively operable switch means shunting said transistor switch for selectively contiNuously energizing said pulse generator, thereby facilitating the application of a cutting current level to said instrument.

Claim 7

The apparatus of claim 4 further including a capacitor interconnecting said low frequency oscillator and said transistor switch for damping the high frequency pulses of said trains.

Claim 8

Electro-surgical apparatus comprising: a utilization circuit including a conductive surgical instrument, said utilization circuit being susceptive of alternatively constituting relatively low and high impedance electrical loads as the area of the interface between said instrument and tissue varies between large and small values under differing conditions of use, a source of high frequency electrical signals, a source of signal trains including a high frequency oscillator and a low frequency oscillator connected to provide low frequency trains of high frequency signals, a power amplifier having an input circuit responsive to said signal trains and an output circuit, and a transformer having a core, a secondary winding wound on said core and connected to said utilization circuit, and a primary winding wound on said core and responsive to said output circuit of said amplifier, said transformer being a step-up transformer in which the number of turns of the secondary winding substantially exceeds the number of turns of the primary winding, said transformer being characterized by having said windings tightly coupled and having a core fabricated of material having a magnetic permeability of approximately 2,000 and configured in the form of a hollow cylinder having closed ends connected by a rod about which said windings are wound, thereby reflecting back to said primary winding the load impedance of said secondary winding and utilization circuit to enable said amplifier to supply useful current to said instrument when said utilization circuit is in its low load impedance condition without producing damaging currents in said amplifier when said utilization circuit is in its high load impedance condition.

Claim 9

Electro-surgical apparatus comprising: a utilization circuit including a conductive surgical instrument, said utilization circuit being susceptive of alternatively constituting relatively low and high impedance electrical loads as the area of the interface between said instrument and tissue varies between large and small values under differing conditions of use, a source of high frequency electrical signals, a source of signal trains including a high frequency oscillator and a low frequency oscillator connected to provide low frequency trains of high frequency signals, a power amplifier having an input circuit responsive to said signal trains and an output circuit, and a transformer having a core, a secondary winding wound on said core and connected to said utilization circuit, and a primary winding wound on said core and responsive to said output circuit of said amplifier, said transformer being a step-up transformer in which the number of turns of the secondary winding substantially exceeds the number of turns of the primary winding, said transformer being characterized by having said windings tightly coupled and having a core fabricated of material having a magnetic permeability of approximately 2,000 and configured in the form of a hollow cylinder having closed ends connected by a rod about which said windings are wound, thereby reflecting back to said primary winding the load impedance of said secondary winding and utilization circuit to enable said amplifier to supply useful current to said instrument when said utilization circuit is in its low load impedance condition without producing damaging currents in said amplifier when said utilization circuit is in its high load impedance condition.