Patent ID: 7977828

Claim:
A stepping motor comprising: a rotor having a drive magnet; and a stator having a drive coil, the drive coil being wound in a tube shape and disposed on an outer peripheral side of the drive magnet; wherein the stator comprises: a first yoke provided with a first end plate part formed in an approximate ring shape, the first end plate part being disposed so as to cover one end face of the drive coil in an axial direction of the rotor; a second yoke provided with a second end plate part formed in an approximate ring shape, the second end plate part being disposed so as to cover an other end face of the drive coil in the axial direction; a plurality of first pole teeth provided in the first yoke, formed to stand up from an inner peripheral end of the first end plate part, and disposed so as to face an outer peripheral face of the drive magnet; and a plurality of second pole teeth provided in the second yoke, formed to stand up from an inner peripheral end of the second end plate part, and disposed so as to face the outer peripheral face of the drive magnet; wherein the plurality of the first pole teeth and the plurality of the second pole teeth are alternately disposed in a circumferential direction of the rotor; wherein a narrow space part where a space becomes narrower in the circumferential direction between the first pole tooth and the second pole tooth adjacent to each other in the circumferential direction is formed at a substantially center position in the axial direction between a first tip end part which is a tip end part of the first pole tooth and a second tip end part which is a tip end part of the second pole teeth; wherein a distance between the first tip end part and the narrow space part in the axial direction is approximately ⅔ of a distance in the axial direction between a second base end part, which is a base end part of the second pole tooth that is formed at a boundary part between the second end plate part and the second pole tooth, and the narrow space part; and wherein a distance between the second tip end part and the narrow space part in the axial direction is approximately ⅔ of a distance in the axial direction between a first base end part, which is a base end part of the first pole tooth that is formed at a boundary part between the first end plate part and the first pole tooth, and the narrow space part.