| 摘要 |
PURPOSE:To decrease noise produced from a pulse motor, by a method wherein fall time of phase current is varied corresponding to a load and smooth rotation is obtained. CONSTITUTION:CPU detects degree of time lapse increase of current flowing through an exciting coil from variation of potential V1 produced in a phase current detecting resistor R5, and estimates load torque of a pulse motor. The CPU transmits three sorts of outputs corresponding to the load torque, and performs control so that any of photo-couplers PC2-PC4 is rendered ON. Consequently, back electromotive force generated at OFF state of exciting signal of each phase is eliminated through any of zener diodes ZD2, ZD3, ZD4. thus the CPU selects a zener diode having optimum zener voltage corresponding to amount of the load torque, and therefore controls the fall time of phase current. |
