| 摘要 |
PROBLEM TO BE SOLVED: To stably perform drive control of a step motor repeating acceleration and deceleration.SOLUTION: A CPU 18 controls a driver 19 so as to apply predetermined drive voltage to a drive coil 14g of a step motor 14a. A constant resistor 14h detects counter electromotive force generated in the drive coil; and a differential unit 18b outputs a differential signal that is difference between the counter electromotive force and drive voltage. A filter 18c having a frequency characteristic set according to a period of the drive voltage performs filtering on the differential signal; and a comparator 18d compares an output signal of the filter and a predetermined reference value to output a comparison result signal. A drive target value generation unit 18a adjusts the period of the drive voltage according to the comparison result signal. |
