| 摘要 |
Elliptical vibrations are generated by combining longitudinal primary resonance vibrations resulting from expansion and contraction of a vibrator in a direction of a central axis and torsional secondary resonance vibrations or torsional tertiary resonance vibrations resulting from twisting of the vibrator around the central axis. A dimension ratio of a rectangle of the vibrator is set such that a resonance frequency of the longitudinal primary resonance vibrations and a resonance frequency of the torsional secondary resonance vibrations or the torsional tertiary resonance vibrations almost match. The vibrator includes a plurality of piezoelectric sheets. The longitudinal primary resonance vibrations and the torsional secondary resonance vibrations or the torsional tertiary resonance vibrations are generated because of formation of activation regions by polarization in a thickness direction of the piezoelectric sheets. |
