| 摘要 |
PROBLEM TO BE SOLVED: To provide a piezoelectric actuator small and thin size and capable of high efficient and stable driving. SOLUTION: A drive circuit 500A computes a differential signal Vc of detection signals Va, Vb in response to the distortion of a vibration plate 10 from detection poles 34A, 34B by a subtraction circuit 501, and generates a delay signal 502 delayed by a predetermined time tp by a delay circuit 502. A comparator 503 is input by the differential signal Vc and a delay signal Vd, and a signal Ve resulting in comparison of a large and small voltages is supplied to a voltage adjustment circuit 504. The voltage adjustment circuit 504, VCO 504, and driver circuit 506 generates a drive signal Vh of frequency based on this comparison result signal Ve. Therefore, the drive circuit 500A detects distortion of the vibration plate 10 and controls the frequency of the drive signal Vh so that the vibration plate 10 is always vibrated in maximum with this distortion. |
