Dynamic fluid pressure bearing, spindle motor, disk drive apparatus and method for manufacturing the dynamic fluid pressure bearing

摘要

A fluid dynamic pressure bearing includes a shaft arranged along a central axis, an annular member fixed to the shaft, a sleeve, a lubricant, and a lubricating film. A stepped surface is provided on the outer circumferential surface of the shaft. The annular member preferably includes a lower surface extending radially with respect to the central axis and arranged to make contact with the stepped surface in the inner edge portion of the lower surface. The sleeve preferably includes an upper surface axially opposed to the lower surface of the annular member. The lubricant is provided between the shaft and the sleeve and between the annular member and the sleeve. The lubricating film is provided on the lower surface of the annular member at least over a region lying radially outwardly of the inner edge portion of the lower surface.