Patent ID: 6674200
Filing Date: 2004-01-06
Classification: F16C,G11B,H02K

Abstract:
A spindle motor comprising:a shaft; a round cone portion being a part of said shaft, and whose diameter changes evenly along said shaft longitudinally; an approximately disk-shaped hub mounted on one end of, for rotating together with, said shaft said hub having a disk-mounting portion on one side thereof: a rotor magnet mounted on the peripherally outer margin of said hub opposite the disk-mounting side; a stator installed opposing a radial edge face of said rotor magnet; a conical cavity whose opening changes in diameter evenly along said shaft longitudinally, to correspond in contour to said cone portion, for accommodating said cone portion, said conical cavity having a base corresponding to the narrower end of said cone portion and an inner peripheral surface opposing a lateral surface of said cone portion across an approximately uniform gap; a member including said conical cavity; oil filling a clearance, including the approximately uniform gap, between said cone portion and said conical cavity, wherein said oil is retained continuously without interruption; and one and only one dynamic-pressure bearing formed in said gap, between the lateral surface of said cone portion and the inner peripheral surface of said conical cavity opposing the lateral surface, said dynamic-pressure bearing including, on at least either said lateral surface of said cone portion or said inner peripheral surface of said conical cavity, grooves provided in one and only one set unbroken axially and in unbalanced herringbone or spiral form, configured so as to heighten pressure heading toward the base of said conical cavity.