| 摘要 |
PURPOSE:To facilitate an easy fine adjustment to a control position by securing such a constitution where a control bit is held by a drive part only at the time of controlling the revolution and then released from the drive part concurrently with stop of revolutions to be held as it is in a state where no force is transferred with an object to be controlled. CONSTITUTION:The rotational frequency of a bit 3, i.e., a motor 1 that is needed to set the target value with a CPU 12 is calculated and the motor 1 is driven. Here the voltage is impressed to a piezoelectric element 8 via a timing control circuit 11 and a drive power supply 9 immediately before the motor 1 is driven. Thus the bit 3 is locked. An object 4 to be controlled is controlled to its target value with the prescribed rotational frequency of bit control part 3A. Then the drive of the motor 1 is stopped via a motor control circuit 10 as soon as the prescribed rotational frequency is attained. At the same time, the impression of voltage is stopped to the element 8 and the bit 3 is unlocked. Thus the object 4 is automatically held at its reset position with no resistance to the restoring force even through the object 4 is liable to reverse the revolutions by its restoring force. Then the object 4 has a contact with the part 3A with no resistance.
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