Patent ID: 7446442
Filing Date: 2008-11-04
Classification: H02K

Abstract:
1. A stepping motor, comprising: a rotatable cylindrical magnet circumferentially divided to be alternately magnetized with different magnetic poles; a first cylindrical coil and a second cylindrical coil disposed in positions where the first cylindrical coil and the second cylindrical coil are concentric with the magnet and axially hold the magnet therebetween; a first stator having a first outer magnetic pole portion axially extending to face one outer peripheral surface side of the magnet at a predetermined interval and excited by the first coil; a second stator having a second outer magnetic pole portion axially extending to face the other outer peripheral surface side of the magnet and excited by the second coil; an output shaft having an inner magnetic pole portion made of a soft magnetic material and fixed to an inner diameter portion of the magnet, the inner magnetic pole portion facing at least one of the first outer magnetic pole portion and the second outer magnetic pole portion within a predetermined axial range and excited by at least one of the first coil and the second coil; and a cylindrical bobbin made of an insulator on which at least one of the first coil and the second coil is wound, wherein the bobbin includes an engaging portion engaged with the axially extending first magnetic pole portion and the axially extending second magnetic pole portion such that a predetermined positional relation is established between relative circumferential positions of the first stator and the second stator.