| 摘要 |
PROBLEM TO BE SOLVED: To provide spindle rotation control technology for a magnetic disk unit by which spindle rotation control is not affected even if a write-in position of servo information is different for each head, head switching is performed at any timing, falling of a carriage supporting the head is caused afterward, and an index period in switching of the head becomes longer ot shorter than a normal value. SOLUTION: The magnetic disk unit adopts a system in which rotation control of a spindle motor is performed based on an index period, in an index period measuring counter circuit 30 measuring an index period every period, when head switching in which a rotation period of a spindle motor 18 becomes abnormal is performed, a measured result of the index period is not updated, but rotation control of the spindle motor is performed with the index period measured before head switching, and rotation control is performed in accordance with switching/non-switching of the head in continuation. COPYRIGHT: (C)2004,JPO
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