| 摘要 |
PURPOSE:To simplify resonance characteristics and improve motor efficiency by a method wherein the vibration system of an ultrasonic wave motor is divided into the inside part and the outside part of a stator and an ultrasonic vibration is induced by a sheet of piezoelectric material. CONSTITUTION:The electrode part of a piezoelectric sheet 13 is divided into an inside part and an outside part so as to create two sets of ultrasonic vibration mode. Combinations of electrodes 21 and 22 and combinations of electrodes 23 and 24 are arranged along the circumference with a phase difference of 90 deg. between each group. A vibration, whose one wavelength corresponds to the one combination of the electrodes 21 and 22, is created and a voltage is also applied to the electrodes 23 and 24 at the identical frequency. The combined mode of the inside ultrasonic wave and the outside ultrasonic wave makes a progressive wave rotate along the circumference direction and this rotation works as the driving force of an ultrasonic wave motor and makes the rotor rotate. |
