JPS55106378A - Driving circuit for watch pulse motor - Google Patents

Abstract

PURPOSE:To reduce the power consumption by changing the phase of the driving pulse at the steady time and the abnormal time each of the driving circuit which applies the different driving pulses to the coil of the step motor at the steady time and the abnormal time each. CONSTITUTION:At the abnormal time with application of the load, the rotational speed is decreased for the rotor of the pulse mortor. And then the induction voltage amplitude decreases for driving coil 227 in driving circuit 110, and detection inverters 228 and 229 of detection circuit 113 generate no detection output. Thus switch pulse phi27 is generated from gate circuit 238, and output phi18 of pulse switching FF239 turns to 0. And the output of selection gates 219 and 220 of waveform conversion circuit 109 are shifted right to have the phase shift of about 0-20m.sec. Thus the same polarity is secured between the last driving pulse of the steady time and the first driving pulse of the abnormal time, and the motor is driven in the high-output torque and by the first driving pulse of the abnormal time. As a result, the power consumption can be reduced at the steady time, thus realizing the reduction for the mean power consumption.