US 2002/0165680 A1 · Output displacement control using phase margin in an ultrasonic surgical hand piece

Abstract

An ultrasonic surgical hand piece is caused to be driven with an output displacement that is correlated with the phase margin, which is the difference of the resonant frequency and the anti-resonant frequency of the hand piece. A frequency sweep is conducted to find the resonant frequency and the anti-resonant frequency for the hand piece. The resonant frequency is measured at a point during the frequency sweep where the impedance of the hand piece is at its minimum. The anti-resonant frequency is measured at a point during the frequency sweep where the impedance of the hand piece is at its maximum. Using a target or specific output displacement, a drive current is calculated based on the phase margin which is the difference between the resonant frequency and the anti-resonant frequency. The hand piece is caused to be driven with the output displacement, by accordingly controlling the current output from a generator console for driving the hand piece.

Claims20

Dependent claims

A method for operating an ultrasonic surgical hand piece comprising the steps of:

measuring a resonant frequency of the hand piece;
measuring an anti-resonant frequency of the hand piece;
calculating a phase margin which is the difference of the resonant frequency and the anti-resonant frequency;
correlating the phase margin with an output displacement;
calculating a drive current based on the correlation of the phase margin with the output displacement;
and
driving the hand piece with the drive current.

4 more elements

Dependencies are inferred from the claim text.

Output displacement control using phase margin in an ultrasonic surgical hand piece

Life of this patent

Output displacement control using phase margin in an ultrasonic surgical hand piece

Life of this patent

Abstract

Claims20