US7077853B2
Expired / Lapsed
US
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Method for calculating transducer capacitance to determine transducer temperature
Assignee: Ethicon Endo Surgery Inc
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Filing: 2001-10-10
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Granted: 2006-07-18
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Expires: 2021-10-10
Abstract
Abstract A method for calculating the capacitance of a transducer (C 0 ) without knowing the exact resonance frequency of a transducer/blade combination is achieved by sweeping across a broad frequency range which contains resonant and non-resonant frequencies where C 0 can be measured. A pre-defined frequency range is set independently of the resonance frequency of a specific transducer/blade combination. C 0 of the transducer/blade is measured at several different frequencies within the pre-defined frequency range to ensure that invalid C 0 measurements are disregarded, and the temperature of the transducer is calculated based on valid C 0 measurements. The determined transducer temperature, based on C 0 measurements, can be used to optimize performance and/or provide a safety shutdown mechanism for the generator.
Inventors
- 👤 Kenneth S. Kramer
- 👤 Eitan T. Wiener
- 👤 William T. Donofrio
- 👤 Kevin Houser
- 👤 Foster B. Stulen
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 15:08
CPC Classifications
A; A61; A61B; A61B17/00; A61B17/32; A61B17/320068; A61B2017/00017; A61B2017/00022; A61B2017/00084; A61B2017/00115; A61B2017/00119; A61B2017/320069; A61B2017/320071; A61B2017/320089
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
186 words
A method for determining temperature of a transducer of an ultrasonic hand piece, comprising the steps of: determining a shunt capacitance of the transducer comprising the steps of; applying an ultrasonic drive signal to the transducer across a pre-defined frequency range; measuring the hand piece impedance at fixed frequency intervals to obtain a measured impedance at each frequency interval; performing a curve fit based on each measured impedance at each frequency interval to obtain a curve fit equation; solving the curve fit equation at equally spaced frequency values to obtain a group of distinct impedance values; calculating a shunt capacitance based on each distinct impedance value; discarding a maximum and a minimum calculated shunt capacitance value to obtain a residual group of shunt capacitances; and averaging the residual group of shunt capacitances to obtain a final shunt capacitance value of the hand piece; calculating the temperature of the transducer based on the shunt capacitance of the transducer; and providing a warning to a user of the hand piece if one of the temperature of the transducer and a rate of change of the temperature is excessive.
Claim 2
Independent Claim
186 words
A method for determining temperature of a transducer of an ultrasonic hand piece, comprising the steps of: determining a shunt capacitance of the transducer comprising the steps of; applying an ultrasonic drive signal to the transducer across a pre-defined frequency range; measuring the hand piece impedance at fixed frequency intervals to obtain a measured impedance at each frequency interval; performing a curve fit based on each measured impedance at each frequency interval to obtain a curve fit equation; solving the curve fit equation at equally spaced frequency values to obtain a group of distinct impedance values; calculating a shunt capacitance based on each distinct impedance value; discarding a maximum and a minimum calculated shunt capacitance value to obtain a residual group of shunt capacitances; and averaging the residual group of shunt capacitances to obtain a final shunt capacitance value of the hand piece; calculating the temperature of the transducer based on the shunt capacitance of the transducer; and providing a warning to a user of the hand piece if one of the temperature of the transducer and a rate of change of the temperature is excessive.
Claim 3
Dependent Claim
169 words
The method of claim 1 , wherein said determining step comprises the steps of: applying an ultrasonic drive signal to the hand piece/blade across a pre-defined frequency range; measuring a first hand piece shunt capacitance when a user first activates the hand piece/blade; measuring a second hand piece/blade shunt capacitance when the surgeon deactivates the hand piece/blade; calculating a time difference between when the hand piece/blade is activated and deactivated using a time when the first measured hand piece/blade shunt capacitance is obtained and a time when the second measured hand piece/blade shunt capacitance is obtained; computing a rate of change value of the hand piece/blade shunt capacitance using the calculated time difference; determining whether the rate of change value of the hand piece/blade shunt capacitance is greater than a predetermined threshold above a value stored in memory; and providing a warning to the user, if the rate of change value of the hand piece/blade shunt capacitance is greater than the predetermined threshold above the value stored in memory.
Claim 4
Dependent Claim
19 words
The method of claim 2 , wherein the predefined frequency range is from approximately 34 kHz to 44 kHz.
Claim 5
Dependent Claim
60 words
The method of claim 2 , wherein said computing step comprises the step of: dividing a difference between the first measured hand piece/blade shunt capacitance and the second measured hand piece/blade shunt capacitance by a difference in time between when the first measured hand piece/blade shunt capacitance is obtained and when the second measured hand piece/blade shunt capacitance is obtained.
Claim 6
Dependent Claim
21 words
The method of claim 2 , wherein the predetermined threshold is a shunt capacitance rate of change value stored in memory.
Claim 7
Dependent Claim
13 words
The method of claim 5 , wherein the predetermined threshold is 120 pF/min.
Claim 8
Dependent Claim
62 words
The method of claim 1 , wherein the curve fit is performed in accordance with the relationship: C 0 = 1 2 π f Z HP , where a, b and c are constants which are calculated via the curve fit and f 0 is a fixed frequency at which the hand piece impedance is measured.
Claim 9
Dependent Claim
19 words
The method of claim 1 , wherein the pre-defined frequency range is from approximately 34.5 kHz to 44.5 kHz.
Claim 10
Dependent Claim
14 words
The method of claim 1 , wherein the fixed frequency Interval is 50 Hz.
Claim 11
Dependent Claim
169 words
The method of claim 1 , wherein the shunt capacitance is calculated in accordance with the relationship: C o = - ( 1 f o ) * ( Z HP 2 - 1 R p 2 ) 1 2 - ( C v1 * C v2 ) ( C v1 + C v2 ) + 1 ( f 0 z ≠ L t ) - C c - C pcb , where C 0 is the shunt capacitance, f 0 is a fixed frequency at which the hand piece impedance is measured, Z HP is the hand piece impedance at the fixed frequency F 0 , R p is a value of a limiting resistor, C v1 and C v2 are values of voltage dividing capacitors, L t is a value stored in memory of the generator which represents a transducer tuning inductor, C c is a capacitance of a hand piece cable and C pcb is a contribution of capacitance from a printed circuit board in the generator.
Claim 12
Dependent Claim
17 words
The method of claim 1 , wherein the group of distinct impedance values comprises eleven impedance values.
Claim 13
Dependent Claim
19 words
The method of claim 1 , wherein the equally spaced frequency values are spaced apart at 1000 Hz intervals.
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| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 2009-07-17 | 2010-01-16 | 2010-07-18 | $2000.00 | Window Closed / Lapsed |
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