Patent ID: 7077853
Filing Date: 2006-07-18
Classification: A61B

Abstract:
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.