Spindle motor and magnetic disk drive

摘要

A rotational member and a stationary member included in a spindle motor provided with air bearings are electrically connected while the bearing is rotating, and abrasion of the rotational member and the stationary member at stages of starting and stopping and damaging the rotational member and the stationary member by external shocks that may be exerted thereon during transportation and handling are avoided. In one embodiment, a sleeve is formed integrally with a motor base. The sleeve has an inside surface serving as a radial-bearing surface that forms a radial bearing together with the outside surface of a rotational shaft, and a thrust-bearing surface that forms thrust bearing together with a thrust plate attached to the rotational shaft. The radial-bearing surface of the sleeve is provided with a recess (groove) for holding lubricating oil while the rotational shaft is rotating. A gap not forming a bearing is formed between the circumference of the thrust plate and the inside surface of the sleeve to hold the lubricating oil while the rotational shaft is rotating.