Patent ID: 7446441

Claim:
An outer rotor type hybrid stepping motor comprising: a stator; a rotor; a magnet disposed axially in one of the stator and the rotor; and a stator core disposed inward of from a gap formed between the stator and the rotor; wherein a stator winding wound around the stator core and the rotor is disposed outside the gap; and assuming A is a cross sectional area in the axial direction of the magnet, D is a gap diameter, L is an aggregate lamination thickness of the stator core in the axial direction, Br is a residual magnetic flux density of the magnet, and K is a coefficient expressed in units of (1/T) (T representing Tesla), the lamination thickness L and the residual magnetic flux density Br are selected such that in the following equation, D×L/A=k×Br, the coefficient k is maintained within a range of 0.56-0.66(1/T).