| 摘要 |
PROBLEM TO BE SOLVED: To automatically work a restart circuit in case an out-of-step should occur so as to restart a motor, by automatically increasing the frequency a little from the automatic start frequency of a motor to desired frequency for a given time, according to the output of a speed judging means. SOLUTION: A speed judging circuit 106 compares analog voltage I with set reference voltage K with a comparator 213, and outputs output J the instant the analog voltage I gets over the set reference voltage K. The pulse of the output J is a signal corresponding to the matter that the step out has occurred. What is more, the value of the set reference voltage K is the quantity corresponding to the rated number of revolutions. By driving a spindle motor 7 that way, the detection of the step out of the motor 7 is performed without fail, and in case that the out-of-step should occur, the motor 7 can be restarted in a short time without fail by automatically switching the revolution command into the output on the side of a restart pattern generator 201. |
