| 摘要 |
PURPOSE:To get rid of a residual displacement due to hysteresis, by securing the application of the output of an oscillating circuit to a piezoelectric element and then applying the AC voltage of the same oscillating frequency as the resonance frequency of the piezoelectric element for a certain period to the piezoelectric element. CONSTITUTION:Piezoelectric elements 21 and 22 are attached to the bases of the rotary heads 19 and 20 which are set at the outer circumference of a rotary head substrate 23. It is possible to apply selectively the output an oscillating circuit 24 and the output of a sawtooth wave generating circuit 12 to the elements 21 and 22. The oscillating frequency of the circuit 24 is set at the resonance frequency of the element 21 and 22. The elements 21 and 22 have the resonance point in terms of the displacement-frequency characteristics. Thus the residual amount of DC displacement due to the hysteresis can be eliminated by applying the AC voltage obtained at a point where the displacement is large. |
