Patent ID: 6841919

Claim:
A drive circuit for a piezoactuator, comprising: at least one piezoelectric element having a first oscillation mode and a second oscillation mode, the at least one piezoelectric element being adapted to oscillate when an AC signal is applied to it, the second oscillation mode having a different oscillation direction than that of the first oscillation mode; a driver for applying an AC drive voltage signal to the at least one piezoelectric element; and a frequency control unit for detecting a first electrical signal from the at least one piezoelectric element indicative of oscillation in the first oscillation mode, for detecting a second electrical signal from the at least one piezoelectric element indicative of oscillation in the second oscillation mode, and for controlling the frequency of the AC drive voltage signal to optimize the phase difference between the first and second electrical signals for a particular operating condition of the at least one piezoelectric element.