Patent ID: 6548922
Filing Date: 2003-04-15
Classification: G04C,H02K

Abstract:
A two-pole step motor for a timepiece comprising: a stator including a high-permeability material, and having a rotor hole; a rotor, installed in the rotor hole, the rotor including a rotor magnet and a rotor axle; and a field coil for excitation, including a magnetic core comprising a high-permeability material and a conductor wound around the high-permeability material, opposite ends of the magnetic core being magnetically bonded to opposite ends of the stator;wherein the stator includes a plurality of holding torque setting means disposed on an inner periphery of the rotor hole at installation angles differing in a direction of the inner periphery, and an initial phase angle &thgr;1 formed by a magnetic field direction line in a direction of a magnetic field produced inside the rotor hole and a magnetizing direction line of the rotor magnet at a standstill position of the rotor based on the respective installation angles of the plurality of the holding torque setting means is in a range of 50 mechanical degrees to 70 mechanical degrees.