| 摘要 |
PROBLEM TO BE SOLVED: To reduce wows and flutters and noises of a stepping motor by a method, wherein the drive power supply voltage level of the stepping motor is fixed and the voltage supply is turned on and off to practice the constant voltage control of the motor current, and a control mode is switched between a constant voltage control mode and a constant current control mode with predetermined timings, while the motor rotates. SOLUTION: When the level of an A/B* signal is H, the A-side of a switch 125 is closed to select a constant current control mode, and when it is L, the B-side is closed to select a constant voltage control mode. The current of a motor is converted into a voltage by a current detection resistor 111, and the voltage is compared with a current reference signal 105 from a CPU 101 by a comparator 113. When the voltage of the current reference signal 105 is higher than the voltage of the motor current signal 112, an on/off signal 114 whose level is H is outputted, and when it is lower, an on/off signal 114 whose level is L is outputted. If the constant current control mode is selected, a current at the time of motor driving is kept constant by turning on and off a switch 115. When the constant voltage control mode is selected, the current can be kept constant by turning on and off a switch 118. Wows and flutters can be reduced, and the low cost control can be practiced by switching the control mode while the motor rotates. |
