| 摘要 |
PURPOSE:To obtain stabilized oscillating condition and improve efficiency, by providing an oscillation detecting electrode annularly along the circumference of a piezoelectric element. CONSTITUTION:The stator of an ultrasonic motor is provided with a piezoelectric element 1 and an elastic body 2. In the piezoelectric element 1, polarization units 1c, 1d are arranged so that the directions of polarization are different by 1/2lambda wave length with each other while non-polarization units la, lb are also arranged. Two sheets of oscillation exciting electrodes 5a, 5b are provided on the inner peripheral surface of the piezoelectric element 1, which is not contacted with the elastic body 2, so as to be opposed to the left and right polarization units 1c, 1d while oscillation detecting electrodes 6 are provided annularly on the outer periphery with a space. Further, an earth side electrode 5c is provided annularly along the whole periphery of the same commonly. According to this constitution, the oscillating condition of the whole of the stator may be detected correctly to control a signal impressed on the piezoelectric element 1, whereby the oscillating condition of the stator may be controlled. |
