Patent ID: 8737017
Filing Date: 2014-05-27
Classification: G11B,H02K

Abstract:
1. A spindle motor of a disk drive apparatus, comprising: a base unit; a stator that includes a stator core and a plurality of coils mounted to the stator core and is disposed above the base unit; a covered cylindrical rotor hub that includes a cover portion positioned above the stator and a side wall portion extending downward from an outer edge of the cover portion; a rotor magnet that is positioned outside the stator in a radial direction thereof and is fixed to an inner circumferential surface of the side wall portion of the rotor hub; and a bearing mechanism that supports the rotor hub and the rotor magnet to be rotatable with respect to the base unit and the stator; wherein a height of the stator core in an axial direction is about 50% or more and about 70% or less than a height of the stator; a torque constant Kt of torque generated between the stator and the rotor magnet is about 4 mN·m/A or more and about 6 mN·m/A or less; and a motor constant Km is about 2 mN·m/(A·√Ω) or more and about 4 mN·m/(A·√Ω) or less.