Patent ID: 8288900

Claim:
A stepping motor comprising: a rotor assembly comprising a magnet and rotatably disposed around a rotation axis as center; and a stator assembly disposed around the rotor assembly and comprising two stator units which are axially coupled to each other and which each comprise a pair of yokes including a first yoke and a second yoke, respectively, and a winding to excite the pair of yokes, wherein the pair of yokes each comprise an annular ring shaped base portion and a plurality of pole teeth bent up from an inner circumference of the base portion and disposed such that the pole teeth of the first yoke and the pole teeth of the second yoke are arranged alternately in a circumferential direction, wherein each of the pole teeth of the pair of yokes comprises a pair of slant sides which are inclined such that a width of the pole tooth decreases in accordance with an increase of distance from the base portion, and wherein at least a part of the slant side of the first yoke is located close to at least a part of the slant side of the second yoke, and wherein a ratio of a dimension of mutually opposing parts of the slant sides with respect to a maximum possible dimension of the slant sides ranges from 0.2 to 0.8.