| 摘要 |
PURPOSE:To drive a motor under optimum conditions by disposing a piezoelectric plate polarized circumferentially between a supporting plate at the center of a stator and a torsional vibration exciting piezoelectric ceramic element, and leading resonance state detecting electrodes from the main surface of the plate. CONSTITUTION:A disc-like or annular piezoelectric ceramic plate 13 polarized circumferentially for detecting a torsional vibration state is disposed between a supporting plate 15 and a torsional vibration exciting piezoelectric ceramic element 12. Resonance state detecting metal electrodes are formed on both side surfaces of the plate 13, and electric terminals 131, 132 are led therefrom. Accordingly, since whether the torsional vibration state is resonant or nonresonant can be detected, a motor can be driven in a state that its driving frequency is always resonance frequency of the torsional vibration. Thus, even if environments such as temperature, etc., is varied, it can be always continuously driven under optimum conditions. |
