Stepping motor for electronic timepiece - has permanent magnetic rotor enclosed by two pairs of curved stator pole shoes

摘要

The stepping motor for an electronic timepiece has a stator winding, supplied with current pulses by the electronic circuit, the stator field causing rotation of a permanent magnetic rotor (1), enclosed between two facing stator pole shoes (3, 4). The rotor (1) is cylindrical and divided into six alternating segmental poles (N.S.). The stator pole shoes (3, 4) have two opposing pairs of curved edges (7a, 8a; 7b, 8b) extending around the rotor (1), with a recessed face (7, 8) between them. The length of the cuved edges of one opposing pair (7a, 8a) is double the length of the curved edges of the other pair (7b, 8b), the former extending over approx. 40 degrees and the latter over approx 20 degrees.