Patent ID: 6822351
Filing Date: 2004-11-23
Classification: H02K

Abstract:
A low-profile stepping motor comprisinga first stator unit including: a first upper stator yoke having a plurality of pole teeth which are formed along its semicircular inner circumference; a first lower stator yoke having a plurality of pole teeth which are formed along its semicircular inner circumference and which mesh with the pole teeth of the first upper stator yoke with a shift by an electrical angle of 180 degrees; and a first coil unit fixedly sandwiched between the first upper and lower stator yokes, a second stator unit including: a second upper stator yoke formed as one piece integrally with the first upper stator yoke, and having a plurality of pole teeth which are formed along its semicircular inner circumference; a second lower stator yoke formed as one piece integrally with the first lower stator yoke, and having a plurality of pole teeth which are formed along its semicircular inner circumference and which mesh with the pole teeth of the second upper stator yoke with a shift by an electrical angle of 180 degrees; and a second coil unit fixedly sandwiched between the second upper and lower stator yokes and arranged horizontally flush with the first coil unit, wherein any two pole teeth adjacent to each other with one thereof being formed on the first upper stator yoke and the other formed on the second upper stator yoke are shifted from each other by an electrical angle of either 90 degrees or 270 degrees, and any two pole teeth adjacent to each other with one thereof being formed on the first lower stator yoke and the other formed on the second lower stator yoke are shifted from each other by an electrical angle of either 90 degrees or 270 degrees, and a rotor assembly including a cylindrical magnet and rotatably disposed in a circular open space defined by the pole teeth of the first and second stator units.