Patent ID: 8416523

Claim:
A disk drive device, comprising: a hub on which a recording disk is to be mounted; a base rotatably supporting the hub through a bearing unit; a core fixed to the base, the 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 plurality of magnetic poles fixed to the hub, the plurality of magnetic poles being arranged to be along the circumferential direction and arranged to radially face the plurality of teeth, wherein at least a majority of the core is a powder-bonding body formed from a magnetic powder, wherein at least one of (a) the surfaces of particles of the magnetic powder and (b) the surfaces of the core is insulated, and at least one of the plurality of teeth includes: a middle portion that extends radially from the ring portion and around which the coil is wound; and an end portion being arranged at an opposite side of the middle portion from the ring portion, and wherein the core is formed so that the thickness of the ring portion in the radial direction is less than or equal to 40 percent of the width of the middle portion in the circumferential direction.