Patent ID: 7235911

Claim:
A stepping motor comprising: a rotating shaft operable to rotate continuously; a magnet including only one permanent magnet magnetized in a single pole and arranged concentrically with the rotating shaft; only one coil wound so as to be concentric with the magnet and to be opposed to the magnet, a predetermined clearance being provided between the magnet and the coil; and a magnetic member that surrounds the coil and that comprises: a magnetic pole interposed between the magnet and the coil, wherein at least one of a recessed groove and a notch is formed at a portion of the magnetic pole, which is separated from an end portion of the magnetic pole so that cogging torque is applied to the magnet, and wherein the magnetic member enables the rotating shaft to self-start from a non-excited stabilized position in which the cogging torque is applied to the magnetic member when the magnet is attracted and repulsed due to an intersection of a direction of a magnetic flux generated when the magnetic pole is excited by an energization of the coil and a polarity direction of the magnet, enables the rotating shaft to rotate to an electromagnetically stabilized position in which the attraction and the repulsive force between the magnet and the magnetic pole are balanced, and enables the rotating shaft to rotate continuously by the attraction and the repulsive force by controlling the energization of the coil at the electromagnetically stabilized position and the non-excited stabilized position.