| 摘要 |
PROBLEM TO BE SOLVED: To precisely detect the abnormality of a non-repeatable run out of a spindle motor. SOLUTION: In a track following control mode in which a head is positioned at a target position of a target track on a disk, head positional error signals that indicate the positional error of the head with respect to the target position are generated every time the location of the head is detected (S1 and S2). In parallel with track following control based on the signals (S3 and S4), a process is conducted to detect the specific frequency components of non-repeatable run out (NRRO) of a spindle motor (SPM) included in the signals. When the amplitudes of the components are deviated from a reference range, it is judged that an NRRO abnormality exists and a write operation is prohibited (S11 to S13).
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