Patent ID: 7570007
Filing Date: 2009-08-04
Classification: H02P

Abstract:
1. A method of controlling a 2-phase stepping motor including A-phase and B-phase magnetic pole sets arranged with a phase difference corresponding to an electrical angle of 90 degrees and driving coils wound around each of the two magnetic pole sets, the method comprising: if a stop position of a rotor is referred to as a 2-phase excitation stop position when the stepping motor is driven in a 2-phase excitation mode in which the rotor is theoretically rotated at a step angle of 90 degrees in electrical angle, a predetermined rotation range of the rotor including the 2-phase excitation stop position is referred to as a first rotation range, and a predetermined rotation range of the rotor other than the first rotation range is referred to as a second rotation range, performing a driving control of driving the stepping motor in an excitation mode in which the rotor is theoretically rotated at a step angle of (360/2 performing a stop control of stopping the rotor by setting the sum of currents supplied to the driving coils to stop the rotor at a target stop position within the second rotation range to be larger than the sum of currents supplied to the driving coils to stop the rotor at a target stop position within the first rotation range, wherein the first rotation range is an electrical angle range of about −30° to about +30° from the 2-phase excitation stop position in a rotation direction of the rotor.