PIEZOELECTRIC ACTUATOR AND DEVICE

摘要

At the center of a piezoelectric element (82), a detection electrode (82C) of substantially rhombic shape is formed. The detection electrode (82C) is formed by containing a vibration node of lateral primary vibration mode, which node is a vibration node of bent secondary vibration mode. Accordingly, the distortion by the vibration of the bent secondary vibration mode is minimized. Consequently, when a phase difference between the drive signal and the detection signal is obtained, it is possible to minimize the affect of the vibration of the bent secondary vibration mode on the phase difference and one drive frequency is decided for a predetermined phase difference. Thus, by controlling the phase difference to be a predetermined value, it is possible to make a vibrator (66) vibrate at a desired drive frequency. Since each vibration mode vibrates at a desired vibration component, it is possible to improve reliability of the drive performance.