| 摘要 |
PURPOSE:To provide a method of driving an ultrasonic motor which gets stable start and stationary property by applying a voltage higher than that at steady state at start, and seeing that it does not pass an unstable region in the middle of the start. CONSTITUTION:When a start signal is provided, a sweep indicator 14 outputs a voltage signal Cv, and an oscillation controller 13 outputs a frequency signal Cf to a voltage control oscillator 7, and sets the frequency f0 and the voltage value V1 of the voltage to be applied to an ultrasonic motor 11 to a value higher than the frequency that the motor shows instability and the value higher than the stationary voltage to drive the motor stably, respectively. Next, the sweep indicator 14 sweeps f0 and V1 toward lower values, and starts the motor, and at the point of time when the current flowing to the driving electrode has reached the specified value i1, it stops the sweep, and after that, it controls f0 and V1 so that the current may keep V1 and operates the motor stably. |
