Permanent magnet step motor with a shiftable rotor

摘要

A step motor for an electronic wristwatch is provided wherein the load on the rotor is reduced. The reduction in the load on the rotor is provided by the configuration of a rotor pinion supporting the rotor and the manner in which same is supported by the rotor support assembly. The rotor pinion includes first and second trunions respectively disposed in first and second bearings. The rotor pinion includes first and second shoulders axially recessed from the ends of the trunions by a predetermined distance so as to define a clearance between the respective shoulders and the respective bearings for each rotary position of the rotor.