| 摘要 |
PURPOSE:To improve the durability of a rotary drum with no generation of sparks and to give no adverse effect to a magnetic circuit for record/reproduction of signals as well as to the revolving performance of a drum, by using a piezoelectric oscillator and a rectifying device at a feed part to an actuator consisting of a piezoelectric element, etc. CONSTITUTION:When a piezoelectric oscillator 3 has a distortion as shown by a broken line, the electric charge is produced by a piezoelectric phenomenon. Thus the electric charge flows into a rectifying device 4 in the form of an alternating current in case said distortion occurs repetitively. This electric charge is turned into an alternating current of frequency fr as long as the oscillator 3 is oscillated by the resonance frequency fr and rectified by the device 4 to be applied to an actuator 5. The displacement amount of the actuator 5 is varied by the applied voltage, i.e., the amplitude of the oscillator 3. Therefore the displacement of the actuator 5 can be controlled with control of the amplitude of the oscillator 3. Thus the actuator 5 for automatic tracking can be driven with no contact. This can avoid the deterioration of durability due to the friction, an evil effect to be given to the revolving performance of a drum and the generation of sparks for a rotary head drum. |
