Patent ID: 8466648
Filing Date: 2013-06-18
Classification: H02P

Abstract:
1. A motor control device for a stepping motor including at least two phase coils, in which coil currents having different phases flow, respectively, and a rotor configured to rotate by periodically switching a phase of the coil current flowing in each phase coil, the motor control device comprising: a control unit which applies a pulse voltage subjected to pulse width modulation, to each of the at least two phase coils of the stepping motor; a back electromotive voltage measuring unit which provides a halt period to temporarily halt the application of the pulse voltage to one of the phase coils when a direction of the coil current flowing in the one phase coil is switched, and which measures a back electromotive voltage induced in the one phase coil during the halt period; an out-of-step detecting unit which detects an out-of-step of the stepping motor if the measured back electromotive voltage satisfies a predetermined out-of-step determination criterion; and a voltage control unit which sets a voltage for all phase coils other than the one phase coil, for which the back electromotive voltage is measured, to a constant voltage during the halt period, wherein the voltage control unit sets a voltage level of the constant voltage to one of a power-supply voltage level and a ground (GND) level, for the all other phase coils.