Method for calculating transducer capacitance to determine transducer temperature
First Claim
1. 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.
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Accused Products
Abstract
A method for calculating the capacitance of a transducer (C0) 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 C0 can be measured. A pre-defined frequency range is set independently of the resonance frequency of a specific transducer/blade combination. C0 of the transducer/blade is measured at several different frequencies within the pre-defined frequency range to ensure that invalid C0 measurements are disregarded, and the temperature of the transducer is calculated based on valid C0 measurements. The determined transducer temperature, based on C0 measurements, can be used to optimize performance and/or provide a safety shutdown mechanism for the generator.
604 Citations
12 Claims
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1. A method for determining temperature of a transducer of an ultrasonic hand piece, comprising the steps of:
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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. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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Specification