Patent ID: 8605376
Filing Date: 2013-12-10
Classification: G02B,H02P

Abstract:
1. A motor comprising a rotor having a magnet circumferentially magnetized with a plurality of poles, a stator including two coils, and a controller configured to control an excitation to each of the two coils separately, wherein the stator further includes a first yoke excited by one of the two coils, a second yoke excited by the other of the two coils, a first rotor detector, and a second rotor detector, each of the first and second rotor detectors being configured to detect polarity changes of a magnetic flux by the magnet as the rotor rotates, wherein the first yoke includes a plurality of magnetic pole tips whose centers are spaced from each other by an electric angle of 360° in a stator circumferential direction, and the second yoke includes a plurality of magnetic pole tips whose centers shift from the centers of the magnetic pole tips of the first yoke in the same direction in the stator circumferential direction by the electric angle of 90°, wherein a center of the first rotor position detector is arranged at the same position as one of the centers of the magnetic pole tips of the first yoke in the stator circumferential direction, and a center of the second rotor position detector is arranged at the same position as one of the centers of the magnetic pole tips of the second yoke in the stator circumferential direction, wherein the controller includes a signal switching unit configured to generate an excitation switching signal used to switch the excitation to each coil, an excitation unit configured to excite a corresponding coil in accordance with the excitation switching signal, and a delay angle operator configured to obtain a first delay angle and a second delay angle whenever the excitation switching signal corresponding to each coil is generated, the first delay angle being a delay amount of the excitation switching signal based on a just past polarity change of a first signal detected by the first rotor position detector, and a second delay angle being a delay amount of the excitation switching signal based on a just past polarity change of a second signal detected by the second rotor position detector, and wherein the signal switching unit generates the excitation switching signal using the first delay angle for the first signal or the second delay angle for the second signal.