Piezoelectric actuator and device

Abstract

Detection electrodes 82D and 82E are formed at positions that include an antinode of a flexural oscillation mode. The strain of flexural oscillation reaches a maximum and the effects on the phase difference in the longitudinal oscillation mode can be cancelled out. The detection electrodes 82D and 82E are formed at the positions of drive electrodes 82B and 82C used to excite the flexural oscillation mode. A phase difference in the flexural oscillation mode opposite in sign relative to the longitudinal oscillation mode is created making it is easy to classify based on the phase difference between a frequency at which the longitudinal oscillation mode is dominant and a frequency at which the flexural oscillation mode is dominant. Thus, reliable control can be achieved based on the oscillation behaviors at each frequency ensuring a satisfactory drive force based on oscillation in the longitudinal oscillation mode.

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