US4429694A
Expired / Lapsed
US
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Electrosurgical generator
Assignee: Wells Fargo Bank NA
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Filing: 1981-07-06
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Granted: 1984-02-07
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Expires: 2001-07-06
Abstract
Abstract A solid-state electrosurgical generator is disclosed which provides output waveforms that are optimized for electrosurgical fulguration. The fulguration output circuitry consists of a radio-frequency tank circuit which is periodically pulsed to produce a periodic damped-sinusoidal output waveform. However, the damping factor is sufficiently low so that many cycles of the waveform occur between periodic input pulses. Although the duty cycle is relatively high compared to prior art devices, cutting and burning effects are prevented by a high impedance output which internally limits fulguration arc current. The fulgurating arc developed by the device is longer and more consistent than that developed by previous devices thereby resulting in superior fulguration.
Inventors
- 👤 Francis T. McGreevy
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 11:20
CPC Classifications
A; A61; A61B; A61B18/00; A61B18/04; A61B18/12; A61B18/1206; A61B2018/00636; A61B2018/0066
Claims Analysis
Total Claims: 30
Claim 1
Independent Claim
158 words
An electrosurgical generator for performing surgical operations on a tissue mass comprising: an active electrode, a return electrode, means for generating a damped oscillatory open circuit output voltage waveform across said electrodes, said waveform being substantially of the form e - ζω.sbsp.n t sin (ω n √1-ζ 2 t+φ), where e is the base of the natural logarithm, ω n is the undamped, natural frequency, ζ is the damping factor and is equal to or less than 0.038, but greater than 0 and φ is a phase angle, said generating means generating a loaded output voltage waveform across said electrodes after an electrical arc forms between said tissue mass and said active electrode, said loaded waveform being substantially of the form e - ζω.sbsp.n t sin (ω n √1-ζ 2 t+φ), where e is the base of the natural logarithm, ω n is the undamped, natural frequency, ζ is the damping factor and is substantially greater than 0.038.
Claim 2
Dependent Claim
158 words
An electrosurgical generator for performing surgical operations on a tissue mass comprising: an active electrode, a return electrode, means for generating a damped oscillatory open circuit output voltage waveform across said electrodes, said waveform being substantially of the form e - ζω.sbsp.n t sin (ω n √1-ζ 2 t+φ), where e is the base of the natural logarithm, ω n is the undamped, natural frequency, ζ is the damping factor and is equal to or less than 0.038, but greater than 0 and φ is a phase angle, said generating means generating a loaded output voltage waveform across said electrodes after an electrical arc forms between said tissue mass and said active electrode, said loaded waveform being substantially of the form e - ζω.sbsp.n t sin (ω n √1-ζ 2 t+φ), where e is the base of the natural logarithm, ω n is the undamped, natural frequency, ζ is the damping factor and is substantially greater than 0.038.
Claim 3
Dependent Claim
19 words
An electrosurgical generator according to claim 1, wherein the open circuit damping factor ζ is substantially equal to 0.038.
Claim 4
Dependent Claim
19 words
An electrosurgical generator according to claim 1, where the open circuit damping factor ζ is substantially equal to 0.025.
Claim 5
Dependent Claim
21 words
An electrosurgical generator according to claim 1, wherein said generating means has sufficient internal impedance to prevent electrosurgical cutting from occurring.
Claim 6
Dependent Claim
26 words
An electrosurgical generator according to claim 4, wherein said internal impedance is substantially equal to or greater than 1000 ohms at the fundamental frequency of operation.
Claim 7
Dependent Claim
27 words
An electrosurgical generator according to claim 4, wherein said internal impedance is substantially equal to or greater than 1000 ohms at a fundamental frequency of 500 kilohertz.
Claim 8
Dependent Claim
135 words
An electrosurgical generator for performing fulguration on a tissue mass, said generator comprising, an electrical tank circuit comprising a capacitor and a transformer having a primary and a secondary winding, said capacitor being connected in parallel with said primary winding, means for repetitively exciting said tank circuit at a repetition rate substantially lower than the resonant frequency of said tank circuit to generate an open circuit damped voltage waveform having substantially the form e.sup.-ζω.sbsp.n.sup.t sin (ω.sub.n √1-ζ.sup.2 t+φ), where e is the base of the natural logarithm, ω n is the undamped, natural frequency, ζ is the damping factor and is equal to or less than 0.038, but greater than 0 and φ is a phase angle, and means connected to said secondary winding for applying the output signals generated thereby to said tissue mass.
Claim 9
Dependent Claim
135 words
An electrosurgical generator for performing fulguration on a tissue mass, said generator comprising, an electrical tank circuit comprising a capacitor and a transformer having a primary and a secondary winding, said capacitor being connected in parallel with said primary winding, means for repetitively exciting said tank circuit at a repetition rate substantially lower than the resonant frequency of said tank circuit to generate an open circuit damped voltage waveform having substantially the form e.sup.-ζω.sbsp.n.sup.t sin (ω.sub.n √1-ζ.sup.2 t+φ), where e is the base of the natural logarithm, ω n is the undamped, natural frequency, ζ is the damping factor and is equal to or less than 0.038, but greater than 0 and φ is a phase angle, and means connected to said secondary winding for applying the output signals generated thereby to said tissue mass.
Claim 10
Dependent Claim
14 words
An electrosurgical generator according to claim 7, wherein ζ is substantially equal to 0.038.
Claim 11
Dependent Claim
14 words
An electrosurgical generator according to claim 7, wherein ζ is substantially equal to 0.025.
Claim 12
Dependent Claim
21 words
An electrosurgical generator according to claim 7, wherein said generating means has sufficient internal impedance to prevent electrosurgical cutting from occurring.
Claim 13
Dependent Claim
26 words
An electrosurgical generator according to claim 10, wherein said internal impedance is substantially equal to or greater than 1000 ohms at the fundamental frequency of operation.
Claim 14
Dependent Claim
27 words
An electrosurgical generator according to claim 10, wherein said internal impedance is substantially equal to or greater than 1000 ohms at the fundamental frequency of 500 kilohertz.
Claim 15
Dependent Claim
122 words
An electrosurgical generator for performing surgical operations on a tissue mass comprising, an electrode for applying electrosurgical power to said tissue mass, an electrical oscillator circuit comprising a capacitor and a transformer having a primary and a secondary winding, said capacitor being connected in parallel with said primary winding, said oscillator circuit having an open circuit Q factor of equal to, or greater than, 13, means for repetitively exciting said oscillator circuit at a repetition rate substantially lower than the resonant frequency of said oscillator circuit to generate said electrosurgical power, and means for coupling said oscillaor circuit to said electrode, so that said generator has an output impedance equal to, or greater than, 1000 ohms at the fundamental frequency of oscillation.
Claim 16
Dependent Claim
122 words
An electrosurgical generator for performing surgical operations on a tissue mass comprising, an electrode for applying electrosurgical power to said tissue mass, an electrical oscillator circuit comprising a capacitor and a transformer having a primary and a secondary winding, said capacitor being connected in parallel with said primary winding, said oscillator circuit having an open circuit Q factor of equal to, or greater than, 13, means for repetitively exciting said oscillator circuit at a repetition rate substantially lower than the resonant frequency of said oscillator circuit to generate said electrosurgical power, and means for coupling said oscillaor circuit to said electrode, so that said generator has an output impedance equal to, or greater than, 1000 ohms at the fundamental frequency of oscillation.
Claim 17
Dependent Claim
16 words
An electrosurgical generator according to claim 13 wherein said Q factor is substantially equal to 13.
Claim 18
Dependent Claim
24 words
An electrosurgical generator according to claim 14 wherein said output impedance is substantially equal to 2789 ohms at a fundamental frequency of 500 kilohertz.
Claim 19
Dependent Claim
16 words
An electrosurgical generator according to claim 13 wherein said Q factor is substantially equal to 20.
Claim 20
Dependent Claim
24 words
An electrosurgical generaor according to claim 16 wherein said output impedance is substantially equal to 1245 ohms at a fundamental frequency of 500 kilohertz.
Claim 21
Dependent Claim
146 words
An electrosurgical generator for performing surgical operations on a tissue mass comprising, an active electrode for applying electrosurgical power to said tissue mass, a timing signal source for generating timing signals, an output transformer having a primary winding and a secondary winding, said secondary winding coupled to said active electrode, a capacitor connected to said primary winding to form a parallel capacitance/inductance oscillator, and means responsive to said timing signals for periodically exciting said oscillator at a frequency substantially less than the resonant frequency of said oscillator into open circuit damped oscillations, being substantially of the form e - ζω.sbsp.n t sin (ω n √1-ζ 2 t+φ), where e is the base of the natural logarithm, ω n is the undamped, natural frequency, ζ is the damping factor and is equal to or less than 0.038, but greater than 0 and φ is a phase angle.
Claim 22
Dependent Claim
146 words
An electrosurgical generator for performing surgical operations on a tissue mass comprising, an active electrode for applying electrosurgical power to said tissue mass, a timing signal source for generating timing signals, an output transformer having a primary winding and a secondary winding, said secondary winding coupled to said active electrode, a capacitor connected to said primary winding to form a parallel capacitance/inductance oscillator, and means responsive to said timing signals for periodically exciting said oscillator at a frequency substantially less than the resonant frequency of said oscillator into open circuit damped oscillations, being substantially of the form e - ζω.sbsp.n t sin (ω n √1-ζ 2 t+φ), where e is the base of the natural logarithm, ω n is the undamped, natural frequency, ζ is the damping factor and is equal to or less than 0.038, but greater than 0 and φ is a phase angle.
Claim 23
Dependent Claim
50 words
An electrosurgical generator according to claim 18 wherein said generator further comprises a return electrode coupled to the secondary winding and the values of said capacitor and transformer are chosen to produce a sufficient output impedance between said active electrode and said return electrode to prevent electrosurgical cutting from occurring.
Claim 24
Dependent Claim
24 words
An electrosurgical generator according to claim 19 wherein said output impedance is substantially equal to 1245 ohms at a fundamental frequency of 500 kilohertz.
Claim 25
Dependent Claim
24 words
An electrosurgical generator according to claim 19 wherein said output impedance is substantially equal to 2789 ohms at a fundamental frequency of 500 kilohertz.
Claim 26
Dependent Claim
15 words
An electrosurgical generator according to claim 18 wherein said transformer has a powdered-iron toroidal core.
Claim 27
Dependent Claim
17 words
An electrosurgical generator according to claim 18 wherein said capacitor has a value of substantially 5.4 nanofarads.
Claim 28
Dependent Claim
17 words
An electrosurgical generator according to claim 18 wherein said capacitor has a value of substantially 2.5 nanofarads.
Claim 29
Dependent Claim
17 words
An electrosurgical generator according to claim 18 wherein said transformer has a primary:secondary turns ratio of 1:5.77.
Claim 30
Dependent Claim
17 words
An electrosurgical generator according to claim 18 wherein said transformer has a primary:secondary turns ratio of 1:9.5.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1987-02-06 | 1987-08-08 | 1988-02-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-02-06 | 1991-08-08 | 1992-02-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-02-06 | 1995-08-08 | 1996-02-07 | $7700.00 | Window Closed / Lapsed |