Patent ID: 7514830

Claim:
A spindle motor for use in holding and rotating a data storage disk, the spindle motor comprising: a rotor assembly supported in the motor so as to be rotatable about a center axis extending in the axial direction of the motor, the rotor assembly including a rotor magnet comprising an annular arrangement of magnetic poles, and a disk mounting portion to which the disk is to be mounted, the annular arrangement of magnetic poles having opposite ends in the axial direction of the motor, and the disk mounting portion constituting an outer peripheral portion of the rotor assembly; a stator opposing an outer peripheral portion of the rotor magnet and spaced radially therefrom such that a gap is present therebetween, the stator including a stator core having a plurality of teeth which are arrayed about the center axis, and an annular core back from which the plurality of teeth extend radially inwardly such that tip ends of the teeth are oriented towards the center axis, and at least one winding in the form of a conductor wire wound around the teeth of the stator core; and a shield sheet of a soft magnetic material, the shield sheet being located between the disk mounting portion of the rotor assembly and the winding in the axial direction of the motor as disposed at the same level in the axial direction as at least a portion of the rotor magnet, the shield sheet having an inner peripheral edge located radially across from and encircling the rotor magnet at a level in the axial direction of the motor between respective outer peripheral edges of the opposite ends of the annular arrangement of magnetic poles, and the outer diameter of the shield sheet being equal to or smaller than that of the annular core back.