Claw-pole synchronous motor for driving a storage device

摘要

There is provided a storage device whose cost is greatly reduced by employing a low-cost claw-pole two-phase synchronous motor as a spindle motor in which the rotation nonuniformity and vertical fluctuation of its shaft are suppressed while suppressing the leakage magnetic flux, by employing an open-loop scheme for motor control, and by mounting a drive circuit on the side of a control LSI for controlling the device to omit a motor control drive circuit (driving IC). The number of basic steps of the claw-pole two-phase synchronous motor is set to 48 steps or more. Stator pole teeth between both sub-assemblies are located within the range of 90 DEG +/-5 DEG in electrical angle. One end surface of a rotor having a field magnet is subjected to index magnetization also serving as rotor chuck magnetization. A magnetic shield plate is arranged on the surface of the rotor opposite to the magnetic head. The claw-pole two-phase synchronous motor having the above arrangement is used as a spindle motor, thereby realizing a low-cost storage device having a simple motor drive circuit by open-loop control.