Patent ID: 7535153
Filing Date: 2009-05-19
Classification: H02N

Abstract:
1. A drive control method for driving a piezoelectric actuator by a drive signal being supplied to said piezoelectric actuator to drive a driven body, said drive control method comprising: detecting a phase difference between said drive signal and a detection signal showing an oscillation state of said piezoelectric actuator; acquiring an optimum phase difference, which is the phase difference that realizes a prescribed drive state of the piezoelectric actuator by sweeping a drive frequency of said drive signal; detecting a phase difference inversion which the phase difference reaches the optimum phase difference again except for the optimum phase difference acquired by said acquiring, by sweeping said drive frequency in a prescribed range including a prescribed drive state frequency corresponding to said prescribed drive state and in a prescribed direction; setting a clamping frequency to a frequency in the side of said prescribed drive state frequency from a phase difference inversion frequency corresponding to the phase difference inversion; prohibiting said drive frequency of said drive signal from reaching said clamping frequency; and making said drive frequency of said drive signal track an optimum phase difference frequency corresponding to said optimum phase difference, so that the phase difference reaches said optimum phase difference, by changing said drive frequency of said drive signal based on a difference size between said phase difference and said optimum phase difference.