| 摘要 |
<p>A detection electrode 82C having substantially rhombus shapes is substantially formed at the center of a piezoelectric element 82. Since the detection electrode 82C is formed at a location including the node of the oscillation in a longitudinal primary oscillation mode and the node of the oscillation in a flexural secondary oscillation mode, the strain due to the oscillation in the flexural secondary oscillation mode becomes minimized. Accordingly, when a phase difference between a drive signal and a detection signal is taken, an influence on the phase difference due to the oscillation in the flexural secondary oscillation mode can be suppressed to the minimum, and thus a drive frequency with respect to a predetermined phase difference is determined to a single value. Therefore, the phase difference is controlled to have a predetermined value, and thus an oscillating member 66 can be oscillated with a predetermined drive frequency. Further, since each of the oscillation modes excites an oscillation with a predetermined oscillation component, the reliability of the drive performance can be improved.</p> |
