CA1114452A - Control circuit for an electrical device - Google Patents

Control circuit for an electrical device

Info

Publication number
CA1114452A
CA1114452A CA306,294A CA306294A CA1114452A CA 1114452 A CA1114452 A CA 1114452A CA 306294 A CA306294 A CA 306294A CA 1114452 A CA1114452 A CA 1114452A
Authority
CA
Canada
Prior art keywords
switch
photovoltaic cell
relay
control circuit
lead
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
CA306,294A
Other languages
French (fr)
Inventor
Donald I. Gonser
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Dentsply Sirona Inc
Original Assignee
Dentsply International Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Dentsply International Inc filed Critical Dentsply International Inc
Priority to CA306,294A priority Critical patent/CA1114452A/en
Application granted granted Critical
Publication of CA1114452A publication Critical patent/CA1114452A/en
Expired legal-status Critical Current

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  • Surgical Instruments (AREA)

Abstract

ABSTRACT OF THE ENCLOSURE
A control circuit for an electrical device which includes a switch that is electrically isolated from other components. The switch is connected in series with a photovoltaic cell and relay means. The photovoltaic cell is illuminated so that closing of contacts of the switch causes actuation of the relay means. The relay means is connected to actuate the electrical de-vice. Voltage at the switch is limited by the voltage produced by the photo-voltaic cell.

Description

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This invention relates to electrical switching devices, More par-ticularly, this invention relates to remote controlled switch devices.
In many types of electrical apparatus, it is necessary to isolate a switch from circuits controlled by the swit;ch, and an object of this invent-ion is to provide a switch device in which apparatus controlled by the switch is electrically isolated from the switch.
In radiofrequency electrosurgical devices and the like, it can be desirable to have a switch close to an active electrode as in a handpiece.
However, if conventional switch leads carrying substantial currents extend to the handpiece, there is a danger of leakage of current from the s~itch leads to a switch actuator to cause burns and the like. A further object of this invention is to provide a switch for an electrosurgical device in which current in switch leads is limited to prevent such burning.
A further object of this invention is to provide a switch operated system which inherently limlts the current which circulates in switch leads.
A further object of this invention is to provide a switch circuit in which power is supplied by circuits of the device controlled thereby but in which circuits of ~he device are fully isolated from the switch circuit.
In accordance with ou~ invention there is provided a control cir-cuit for an electrical device which comprises photovoltaic cell means, s~itch means, and relay means, means for illuminating the photovoltaic cell means, , closing of contacts of the switch means causing actuation of the relay means, and ~eans connected to the relay means for actuating the electrical device, voltage at the switch means being limited by the voltage produced by the photovoltaic cell means.
Briefly, this invention provides a switch circuit in which a cur-rent for operating a relay or the like is supplied by a photovoltaic cell.
The relay actuates auxillary contacts which actuate a device controlled by the switch circuit. The ~hotovoltaic cell can be powered by a radiating .: :

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source or lamp which, in turn, can be powered by an appropriate electrical power source, which can be a portion of the device controlled by the switch circuit. The power circu:its of the device are fully isolated from the photo-voltaic cell because there is no direct connection therebetween~ and the power circuits are similarly isolated from the leads which sxtend to the switch.
The current supplied by the photovoltaic cell is limited by the electrical characteristics of the photovoltaic cell and inherently cannot exceed a given output voltage at optical saturation, which can be sufficiently low that there is limited potential danger if the vol~age at the switch contacts reaches an operator. When the device controlled by the switch is an electrosurgical de-vice, and the switch is in a handpiece, an active lead of the electrosurgical device can be shielded and can be closely related to ground so that there can be no substantial leakage of radiofrequency current from the active lead to the switch leads.
The above and other objects and features of the invention will be apparent to those skilled in the art to which this invention pertains from the following detailed description and the drawing, which is a schematic view show-ing a switch circl~t constructed in accordance with an embodiment of this in-vention, the switch circui~ being shown in conjunction with a radiofrequency electrosurgical device~
In the drawing is ~hown a circuit for a radiofrequency electro-surgical device which includes a radiofrequency generator 10 (not shown in de-tail). The radiofrequency generator 10 is coupled through a condenser 12 to a primary winding 13 of a coupling transformer 14. One side of a secondary winding 15 of the coupling transformer 14 is coupled to an active power lead 16 thrq~h a condenser 17. The active power lead 16 can be the inner or shielded conductor of a coaxial cable 18. The outer conductor or shield of the coaxial cable 18 is connected to a return side o~ the secondary winding 15 and through a condenser 19 and a monitor device 21 to ground. The monitor de-c~

: ~ . . ,: , ' ' vice can be of the t-ype shown in my co-pending Canadian applica-tion Serial No.240,630 D.I. Gonser filed Movember 27, L975 and provides a low impedance path from the shield of the coaxial cable 18 to ground.
The active power lead 16 powers an active electrode 22. A passive electrode 23 is coupled to the return side of the secondary winding 15 through a condenser 24.
Operation of the radiofrequency generator 10 is controlled by a switch assembly 26 mounted in a handpiece 27 which supports the acti~e elec~
trode 22. The switch assembly 26 includes switch arms 28 and 29, which are carried on a shaft 31. The shaft 31 is pivotally mounted in appropriate bear-ings (not shown). When a push button 32 is depressed, the switch armi~129 en-gages a contact 33 to which a lead 34 is attached. When a push blltton 36 is depressed, the switch arm 28 engages a contact 37 to which a lead 38 is at-tached. A lead 39 is attached to the switch arms 28 and 29. The lead 39 is also attached to a tubular~electrical shield 41~ The leads 34 and 38 extend through the electrical shield 41~
The leads 34 and 38 are connected through radiofrequency inductances 47 and 48 to relay coils 44 and 46, respectively. The relay 44 includes con-tacts 44A and 44B, which are attached to leads 51 and 52, respectively. The leads 51 and 52 can be part of the control circuitry of the radiofrequency generator 10 (not shown in detail), which leads 51 and 52, when connected ~o-gether, permit the radiofrequency generator to deliver a selected radiofre-quency electrosurgical current, such as a ¢utting current, to the transformer 14, the a~t~e pQwer lead 16 and the active electrode 22. The relay 46 in-cludes contacts 46A and 4~8, which are attached to leads 54 and 56~ respecti~e-. . .
ly, Tho leads 54 and 56 can ba part of the control c1rcuitry of the radio-frequency generator ~, which leads 54 and 56, when connected together, permit the radiofrequency generator to deliver another selected radiofrequency elec_ trosurgical current, such as a coagulating current, to the transformer 14, the ~--:~

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.2 active power lead 16 and the active electrode 22.
Power for actuating the relay coils 44 and 46 is supplied by a photovoltaic cell 58. A lead 59 connects the photovoltaic cell 58 to the re-lay coils 44 and 46. A lead 61 connects the photovoltaic cell 58 to ground and to the shield 41. Capacitors 63 and 64 are connected between the lead 34 and the leads 38 and 61~ respectively, and permit radiofrequency current which may reach the leads 34 and 3B to return to ground without passing through the photovoltaic cell 58 and the relay coils 44 and 46. The radio-frequency inductances 47 and 48 prevent such radiofrequency current pass:ing through the photovoltaic cell 58 and the sensitive relay coils 44 and 46.
The photovoltaic cell 58 can be illuminated by an appropriate lamp 66, which can be powered by leads 59 and 61. The leads 59 and 61 can be con-nected to an appropriate portion of the circuitry of the radiofrequency gen-erator to provide the necessary voltage to operate the lamp 66. The photo-voltaic cell 58 can be designed to have an output of 0.6 volts D.C. and a cur-rent of 60 milliamperesD Such a cell can operate a sensiti~e relay such as a 7~Potter-Brumfield relay ~P-2109. The lamp 66 can be a low voltage annuncia-tor incandescent tungsten filament lamp such as a 7~Sylvania 6~B or 12R~ annun- :
ciator.lamp. Such a lamp, when operated at 5q~ of full output rating, has a very long life and supplies sufficient radiant energy to optically saturate the photovoltaic cell.
.
The voltage at the contacts of the switch operating push buttons 32 and 36 is limited by the characteristi.cs of the photovoltaic cell 58 and cannot exceed the output voltage of the photovoltaic cell 58 at optical satu-ration~ whlch can be sufficiently low that there is no.3ubstantial danger of radiofrequency burns to the operator at the push buttons. The switching leads .
34 and 38 are isolated from the active power lead 16 by the shield 18 of the coaxial cable which sur:rounds the active power lead 16 and the shield 41 sur- ~ -rounding the gwitching leads 34 and 38 to prevent le.a~a~ of radiofrequency Trade Mark ~4~

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current between the active power lead -L6 and the .switching leads 34 and 38.
The switch operating circuit illustrated in the drawing and des-cribed above is subject to modification without departing from the spirit and scope of the appended claims.

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Claims (9)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A control circuit for a radiofrequency electrosurgical device in-cluding a radiofrequency generator, a handpiece, an active electrode means supported on the handpiece, and switch means mounted in the handpiece which comprises photovoltaic cell means and relay means connected in series with the switch means, means for illuminating the photovoltaic cell means, whereby closing of contacts of the switch means causes actuation of the relay means, and means connected to the relay means for causing the radiofrequency genera-tor to power the active electrode, voltage at the switch means being limited by the voltage produced by the photovoltaic cell means.
2. A control circuit as in claim 1 wherein there is an active power lead powered by the radiofrequency generator and connected to the handpiece to power the active electrode, switch lead means connecting the switch means with the relay means and the photovoltaic cell, and an electrical shield separating the active power lead from the switch lead means.
3. A control circuit as in claim 2 wherein the electrical shield sur-rounds the active power lead.
4. A control circuit as in claim 2 wherein the electrical shield sur-rounds the switch lead means.
5. A control circuit as in claim 2 wherein the electrical shield in-cludes first shield means surrounding the active power lead and second shield means surrounding the switch lead means.
6. A control circuit as in claim 1 wherein there is radiofrequency in-ductance means in series with the switch means, the relay means, and the photo-voltaic cell to protect the photovoltaic cell and the relay means from radio-frequency current.
7. A control circuit as in claim 1 wherein there is switch lead means connecting the switch means with the relay means and the photovoltaic cell and there is capacitor means coupling the switch lead means to ground to direct radiofrequency current from the photovoltaic cell and the relay means.
8. A control circuit for an electrical device which comprises photovoltaic cell means, switch means, and relay means, means for illuminat-ing the photovoltaic cell means, closing of contacts of the switch means causing actuation of the relay means, and means connected to the relay means for actuating the electrical device, voltage at the switch means being lim-ited by the voltage produced by the photovoltaic cell means.
9. A control circuit for an electrical device including a handpiece and switch means mounted in the handpiece which comprises photovoltaic cell means and relay means connected in series with the switch means, means for illuminating the photovoltaic cell means, whereby closing of contacts of the switch means causes actuation of the relay means, and means connected to the relay means for causing actuation of the electrical device, voltage at the switch means being limited by the voltage produced by the photovoltaic cell means.
CA306,294A 1978-06-27 1978-06-27 Control circuit for an electrical device Expired CA1114452A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CA306,294A CA1114452A (en) 1978-06-27 1978-06-27 Control circuit for an electrical device

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CA306,294A CA1114452A (en) 1978-06-27 1978-06-27 Control circuit for an electrical device

Publications (1)

Publication Number Publication Date
CA1114452A true CA1114452A (en) 1981-12-15

Family

ID=4111781

Family Applications (1)

Application Number Title Priority Date Filing Date
CA306,294A Expired CA1114452A (en) 1978-06-27 1978-06-27 Control circuit for an electrical device

Country Status (1)

Country Link
CA (1) CA1114452A (en)

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