Patent ID: 6836388
Filing Date: 2004-12-28
Classification: F16C,G11B

Abstract:
A spindle motor, comprising:a shaft; a sleeve formed with a through-hole for rotary-play insertion of the shaft; a rotor having a round top plate in the rotational center of which the shaft is constituted integrally, and a circular cylindrical wall depending from the top plate along its outer rim; a cover member for closing over one end of the through hole formed in the sleeve; micro-gaps formed continuing between an upper-end face of said sleeve and a bottom face of said rotor top plate, an inner circumferential surface of said sleeve and an outer circumferential surface of said shaft, and an inner face of said cover member and an end face of said shaft; oil retained continuously without interruption within said micro-gaps throughout their entirety; a radial dynamic pressure bearing section configured between said sleeve inner-circumferential surface and said shaft outer-circumferential surface, for inducing hydrodynamic pressure into said oil when said rotor spins; a thrust bearing section configured on at least one of either said sleeve upper-end face or said top plate bottom face, and furnished with dynamic-pressure-generating striations for imparting to said oil radially inward-heading pressure when said rotor spins; herringbone grooves being a contiguous pair of spiral grooves for generating essentially equal pressure, provided as dynamic-pressure-generating striations in said radial dynamic-pressure bearing section; and an axial support section, formed between said cover member inner face and said shaft end face, having pressure essentially balancing radially inward-heading pressure generated in said thrust bearing section, wherein said rotor is lifted through cooperation of said thrust bearing section and said axial support section.