| 摘要 |
PURPOSE:To improve rotation characteristics of a rotor by mounting an electromagnet on either a rotor or a stator, mounting a magnetic substance on the other, bringing the rotor into magnetic pressure contact with the stator, and controlling a current to be supplied to the electromagnet to adjust the magnetic force. CONSTITUTION:When a current flows through a control circuit 20 for an electromagnet and a controller 13 for a high frequency drive voltage, a progressive wave is generated in a stator 1 and a detected signal is simultaneously input from a feed-back electrode 16 to the controller 13 for a high frequency drive voltage and the control circuit 20 for the electromagnet. The control circuit 20 for the electromagnet compares an input signal with the reference signal and, based on a difference between the signals, supplies a suitable current to the electromagnet so that it can generate a suitable pressure-contact force between a rotor 4 and the stator 1. On the other hand, the controller 13 for the high frequency drive voltage adjusts the amplitude and the frequency of the current to be supplied to a piezoelectric substance 3 based on an input signal. |
