PURPOSE: To accurately obtain synchronization of forward and reverse rotation by arranging the first detecting element between the first/second set vibrators further the second detecting element in both ends of the first detecting element.
CONSTITUTION: Voltage in accordance with a deflection amount of a stator part 12 is generated by a detecting element 50, and its output is input to an oscillating circuit OSC through a smoothing circuit SC1 of a driving circuit 100. Voltage in accordance with a traveling wave is generated in the detecting element 50 by a traveling wave, generated in the stator part 12, and fed back to the oscillating circuit OSC through the smoothing circuit SC1. When the voltage is low generated in the detecting element 50 (when amplitude of the traveling wave is small), the amplitude of the traveling wave is controlled in a direction of increasing by oscillating a frequency by the oscillating circuit OSC to approach a resonance frequency of the stator part 12. On the other hand, when the voltage is high generated in the detecting element 50 (when the amplitude of the traveling wave is large), the amplitude of the traveling wave is decreased by separating the frequency, oscillated by the oscillating circuit OSC, from the resonance frequency of the stator part 12.
AOYAMA MUTSUO
UMEMURA CHIAKI
KUWABARA YASUO
SAGARA SHINJI
FUKOKU KK