Electric step micromotor for watches - has non ferromagnetic stator and rotor made from two discs having facing alternating magnetic poles

摘要

The motor comprises a rotor rotating in bearings and made as two discs. Opposite alternating magnetic poles have their field axially directed to face one another. A stator has a control winding placed between the rotor discs and a locking device for stopping the rotor in specific angular positions w.r.t. deenergised stator. The stator is made of a non-ferromagnetic material and the locking device is provided with a gear wheel arranged in the stray or scattering field of the rotor magnets near the butt end of the stator winding. This permits reduction of influence of inaccuracies in assembly upon the motor torque, localization of the magnetic flux within the motor volume and decrease of effects of external magnetic fields upon the operation of the micrometer. The stator winding is made as a series of small circular coils, or as a single coil whose shape is oval or triangular.