Patent ID: 8184396
Filing Date: 2012-05-22
Classification: G11B

Abstract:
1. A disk drive device comprising: a hub on which at least one recording disk is to be mounted; a base rotatably supporting the hub through a bearing unit; a stator core fixed to the base, the stator core having a ring portion and a plurality of teeth that extend radially from the ring portion; coils wound around the plurality of teeth; and a drive magnet fixed to the hub, the drive magnet being magnetized for driving and arranged to radially face the plurality of teeth, wherein the hub includes, around the circumference, an outside bank of which the center is a rotational axis, and a support surface of the outside bank on which the recording disk is to sit where, when the hub rotates, the fourth harmonic of the rotational frequency of the axial run-out on the support surface is smaller than 0.1 μm.