JPS5558765A - Step motor for electronic timepiece - Google Patents

Abstract

PURPOSE:To stably reverse a step motor for a timepiece, by supplying the motor with pulses of optimal width and driving frequency adapting to the construction of the motor and the environment around it in use. CONSTITUTION:Reversing pulses are so set that a pulse is cut off at a point D on a curve which shows the rotation angle of a rotor, time and induced voltage in Fig. The reversing pulses shown in Fig. (a) are applied to a step motor. After first reversal is performed, it is judged whether the timing of the cutting-off of the pulse P3 is right or wrong, thereby effecting appropriate pulse width adjustment. The output of an oscillation circuit 90 is frequency-divided by the flip-flop of a frequency divider 91 and then entered into a wave form synthesis circuit 92. Forward and backward driving pulses are synthesized by a forward and backward driving signal circuit 98 and the wave form synthesis circuit 92 to drive the motor 96 through a driving circuit 94. After a reversing pulse width and step number control circuit 93 adjusts the width of the pulse by the motor vibration state detection output of a detector circuit 95, the pulse is applied to the driving circuit 94.