| 摘要 |
PURPOSE:To perform ultraprecise positioning feedback by selecting the driving frequency which can perform low-speed stable operation. CONSTITUTION:In case that the target value inputted into a CPU6, that is, the set quantity of shifting of a rotor is large, the frequency selecting command information 6a outputted from PI10b and 10D selects V1 as the input to be inputted into VCO5. At that time, a piezoelectric element is supplied with an AC signal of frequency F1 in the vicinity of the resonance frequency of the stator of a motor and besides on high frequency side. Moreover, the AC signals of A phase and B phase outputted from power amplifiers 3a and 3b become ones f1 in frequency and large in amplitude. Accordingly, the rotor of the motor 1 comes up to the target value at high speed. When the rotor reaches the vicinity of the target value, CPU6 changes over the switch by the signal from a detector 2 thereby putting it in such condition that voltage V2 is applied to VCO5, so the frequency of A phase and B phase become f2, and it becomes smaller than frequency f1. Accordingly, the motor comes up to the target value at low speed, and it stops accurately at target value. |
