| 摘要 |
PURPOSE: To accurately know the rotational speed of an ultrasonic motor easily and at low cost. CONSTITUTION: A part where the rigidness is unequal is made by such a method as to form grooves 160 or 162, or a hole 164 at one part of a rotor 101, or bond an additional mass 166, or to do the like (by such a method in which a section where friction is unequal does not occur for the contact between the rotor 10a and a resonator). The output corresponding to the rotational speed of the rotor is obtained from the change of resonation frequency by detecting the change of resonation frequency of the resonation system composed of the resonator and the rotor which occurs by the formation of this section where the rigidity is unequal. |
