Spindle motor and rotator device

摘要

A spindle motor having a simplified construction with reduced axial and radial deflection while avoiding the half whirl phenomenon includes a motor frame, a rotating shaft supporting a rotor, a stator and stator coil, a permanent magnet opposing the stator, and a liquid dynamic pressure bearing. Magnetic centers of the permanent magnet and stator coil, in the axial direction of the rotating shaft, are substantially matched. The liquid dynamic pressure bearing comprises opposing surfaces of the rotating shaft and the housing. The rotating shaft has a disk-shaped thrust bearing portion disposed in a first portion of a cylindrical hole of the housing, and a radial bearing portion disposed in a second portion of the cylindrical hole. Lubricating oil fills a space between the cylindrical hole and the thrust bearing portion and radial bearing portion, and a presser ring is pressed and fixed into a third portion of the cylindrical hole to seal the bearing. A boss portion of the rotor is fixed to a rotor supporting portion of the rotating shaft so that an inner peripheral surface of the boss portion mates with an outer peripheral surface of the rotor supporting portion. The rotating shaft has three axially-spaced portions, with the disk-shaped thrust bearing portion formed between and having a larger diameter than the other portions. A stage is provided between the thrust bearing portion and the rotor supporting portion to serve as a seat for installation of the boss portion.