Transformer coupled power transmitting and isolated switching circuit

• US 3,897,788 A
• Filed: 01/14/1974
• Issued: 08/05/1975
• Est. Priority Date: 01/14/1974
• Status: Expired due to Term

• Current Assignee: David W. Newton
• Original Assignee: David W. Newton
• Inventors: Newton, David W.
• Primary Examiner(s): Gaudet, Richard A.
• Assistant Examiner(s): Cohen, Lee S.
• Application Number:
  US05/433,059
• Time in Patent Office: 568 Days
• Field of Search: 128/303.14,303.17,303.13,303.1 323/6,8,22T,22SC,62
• US Class Current: 606/37
• CPC Class Codes: A61B 18/12 by passing a current through the tissue to be heated, e.g. high-frequency current
• CPC Class Codes: A61B 18/1206 Generators therefor
• CPC Class Codes: A61B 2018/0066 without feedback, i.e. open loop control
• CPC Class Codes: Y10S 128/908 Patient protection from electric shock
• CPC Class Codes: Y10S 323/911 Medical electronics

Abstract

A transformer coupled power transmitting and isolated switching circuit is disclosed for use in an electrosurgical apparatus to transmit power from a power generator to a utilization instrument for enabling electrosurgery and to transmit mode information from the utilization instrument to the power generator for enabling control of the operational mode of the generator. The electrosurgical power generator is coupled to the utilization instrument through an isolating transformer. The isolating transformer is loaded in a preselected manner under the control of a logic circuit with the load on the isolating transformer then being sensed and the sensed loading information utilized to control the mode of operation of the power generator to assure that power generator operates in the desired mode for the electrosurgery function then required.

Claims

1. In an electrosurgical apparatus having a power generator and a utilization instrument, a power transmitting and isolating control circuit to transmit power from the power generator to the utilization instrument and to transmit mode information from the utilization instrument to the power generator, the said transmitting and isolating control circuit comprising:

mode control means at said utilization instrument;

transformer means;

transformer loading means connected with said transformer means to load the same;

load control means responsive to said mode control means and connected with said transformer loading means for establishing a predetermined loading on said transformer means by said transformer loading means;

power generating means connected with said transformer means;

sensing means connected with said power generating means to sense the loading of said transformer means; and

power generating control means connected with said sensing means and responsive to said loading sensed by said sensing means to thereby control the mode of operation of said power generAting means.

2. The power transmitting and isolating control circuit of claim 1 wherein said mode control means has two different settings, wherein said load control means establishes different predetermined loadings of said transformer means responsive to said different settings of said mode control means, and wherein said power generating control means controls said power generating means to operate in different preselected modes depending upon the setting of said mode control means.

3. The power transmitting and isolating control circuit of claim 2 wherein said mode control means has a first setting for electrosurgical cutting and a second setting for electrosurgical coagulation, and wherein said power generating means operates in a cut mode when said mode control means is in said first setting and operates in a coagulation mode when said mode control means in said second setting.

4. The power transmitting and isolating control circuit of claim 1 wherein said sensing means includes demodulator means for sensing loading of said transformer means.

5. The power transmitting and isolating control circuit of claim 4 wherein said demodulator means includes an integrated circuit having a precisely selected resistance means connected therewith.

6. The power transmitting and isolating control circuit of claim 5 wherein said integrated circuit includes a selection circuit for precise selection of said resistance means to be utilized in said demodulator means.

7. The power transmitting and isolating control circuit of claim 6 wherein said selection circuit includes a selector switch, a plurality of resistances selectively introduceable into said selection circuit by said selector switch, a meter, and signal processing circuitry including an operational amplifier and series connected transistor connecting opposite sides of said meter with predetermined points in said power transmitting and isolating control circuit and with said selector switch of said selection circuit.

8. In an electrosurgical apparatus, a power generating and isolating control circuit comprising:

isolating transformer means;

transformer loading means connected with said transformer means to load the same;

load control means connected with said transformer loading means for establishing at least one predetermined loading on said transformer means by said transformer loading means;

said transformer loading means including a first transistor the conductive state of which is controlled by said load control means;

power generating means connected with said transformer means; and

power generating control means connected with said power generating means to sense at least said predetermined loading of said transformer means and responsive thereto controlling operation of said power generating means, said power generating control means including demodulator means for sensing loading of said transformer means and decoding and control means for establishing operation of said power generating means in response to said sensed loading of said transformer means, said decoding and control means including a second transistor the conductive state of which is responsive to the conductive state of said first transistor in said transformer loading means, and said decoding and controlling means also including first and second signal processing means connected with said second transistor in said decoding and control means to provide an output for only one of said signal processing means depending upon the sensed loading of said transformer means.

9. In an electrosurgical apparatus, a power generating and isolating control circuit comprising:

an isolating transformer having primary and secondary windings;

a first transistor across the secondary winding of said isolating transformer for loading said isolating transformer;

a logic circuit means for controlling conduction of said first transistor to thereby establish two predetermined different loadings of saId transformer;

an oscillator means for generating an RF signal and coupling the same to the primary winding of said isolating transformer;

a demodulator means connected with said oscillator for sensing the loading of said isolating transformer;

a decoder means connected with said demodulator means, said decoder means including a second transistor the conduction of which is dependent upon the conduction of said first transistor, said decoder means also including first and second processing circuits connected with said second transistor in a manner such that said first signal processing circuit provides an output signal when a first of said predetermined transformer loadings is sensed by said demodulator means and said second signal processing circuit provides an output signal when the second of said predetermined transformer loadings is sensed by said demodulator means whereby separate modes of operation of said oscillator means can be established.

10. The power generating and isolating control circuit of claim 9 wherein said logic circuit means also includes a switch means to establish a cut mode and a coagulation mode, said switch means controlling said logic circuit means to effect loading of said transformer in a different predetermined manner for each said mode, and wherein said circuit means further includes control means connected with said signal processing circuits to cause said oscillator means to operate in the mode selected at said switch means.

11. The power generating and isolating control circuit of claim 10 wherein said first transistor is caused to continuously conduct to load said transformer continuously when said switch means is positioned for coagulation mode, said continuous loading of said transformer being sensed by said demodulator means to cause said second transistor to be continuously non-conductive so that said first signal processing circuit produces an output to establish said coagulation mode and wherein said first transistor is caused to be repeatedly alternated between conductive and nonconductive states to pulse load said transformer, when said switch means is positioned for cut mode, said pulse loading being sensed by said demmodulator means to cause said second transistor to repeatedly alternate between conductive and nonconductive states so that said second signal processing circuit provides an output to establish said cut mode.

12. In an electrosurgical apparatus, a power generating and isolating control circuit comprising:

isolating transformer means;

transformer loading means connected with said transformer means to load the same;

load control means connected with said transformer loading means for establishing at least one predetermined loading of said transformer means by said transformer loading means;

said transformer loading means including a first valve means the conductive state of which is controlled by said load control means;

power generating means connected with said transformer means; and

power generating control means connected to said power generating means to sense at least said predetermined loading of said transformer means and responsive thereto controlling operation of said power generating means, said power generating control means including demodulator means for sensing loading of said transformer means and decoding and control means for establishing operation of said power generating means in response to said sensed loading of said transformer means, said decoding and control means including a second valve means the conductive state of which is responsive to the conductive state of said first valve means in said transformer loading means, and said decoding and controlling means also including first and second signal processing means connected with said second valve means in said decoding and control means to provide an output for only one of said signal processing means depending upon the sensed loading of said transformer means.