International Business Machines Corporation

Akihiro Ohyama

Naoyuki Kagami

Kiyoshi Satoh

Akira Tokizono

Shinichi Matsuzaki

Koichi Takeuchi

Yasuhito Shimizu

A bearing mechanism of the present invention has a first bearing and a second bearing disposed at different positions in an axial direction. Each bearing has an inner race, an outer race, and balls. A shaft holds the inner races of both bearings in an axially separated manner, while a supporting member holds the outer races of both bearings in an axially separated manner. The balls of the bearings have a different coefficient of linear expansion than that of the inner and outer races. The inner and outer races of each of the bearings are fixed in an axially shifted manner, whereby pre-loaded pressures are applied between both the inner race and the balls, and between both the outer race and the balls. As the temperature changes, the supporting member has a compensation member that can change a distance between the outer races in a changing ratio different from a changing ratio of the distance between the inner races.

Spindle motor structure using ceramic ball bearing for hard disk drive

A spindle motor start up method wherein a torque balance between the stator and rotor is broken so as to avoid startup malfunctions, and thereby improve motor startup time in spindle motors prone to startup malfunctions, such as hard disk drive motors having a 4:3 ratio of the number of rotor magnetic poles to the number of stator slots. Processes for breaking a torque balance according to the present invention include: (1) gradually decreasing an initial commutation (switching of each phase) frequency at the startup timing from a frequency higher than a commutation frequency in a conventional startup; (2) gradually decreasing an initial commutation frequency at the startup timing from a frequency higher than a commutation frequency in a conventional startup to a low frequency, and next, gradually increasing the initial frequency from the low frequency; (3) changing a drive current of the spindle motor so as to break a torque balance between the spindle motor stator and rotor; (4) monitoring a back electromotive force detection signal while commutating, and restarting commutation when the back electromotive force detection signal is not detected; and (5) monitoring a back electromotive force detection signal while commutating, resetting the commutation at a time in a commutation sequence after an initial commutation from a first phase to a second phase, and restarting the commutation from the first phase to the second phase.

Spindle motor startup method and apparatus

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Tokyo-to, Japan

Akihiro Ohyama