Patent ID: 8368282

Claim:
A disk drive device comprising: a hub on which a recording disk is to be mounted; a base configured to rotatably support the hub via a bearing; a core that is fixed to the base and includes a circular portion and S salient poles extending from the circular portion in the diameter direction, where S is a natural number greater than or equal to 3; a three-phase coil formed by each of the S salient poles being wound; and a magnet that is fixed to the hub and faces the S salient poles in the diameter direction, and that is provided with P driving magnetic poles in the circumferential direction, where P is a natural number greater than or equal to 2, wherein the peak-to-peak value of a fundamental frequency component of cogging torque based on the LCM of S and P, where S is the number of the salient poles of the core and P is the number of the driving magnetic poles of the magnet, is less than or equal to 0.2 (mN·m).