Patent ID: 7046477

Claim:
A disk drive which performs seek control for moving a head to a target position on a disk rotated by a spindle motor and track following control for settling the head within a target range for the target position, the disk drive comprising: a position error detector configured to detect a position error between a position of the head and the target position; an adaptive learning device configured to acquire, through adaptive learning, a runout component of a disk runout which may occur as the disk rotates, the runout component being contained in the detected position error; a nonvolatile storage device to which a learned value for the runout component acquired by the adaptive learning device through the adaptive learning during manufacture of the disk drive is pre-saved; a main controller which controls relearning of the runout component by the adaptive learning device to acquire a relearned value for the runout component during activation of the disk drive, the learned value for the runout component saved to the nonvolatile storage device being used as an initial value for the adaptive learning during the relearning of the runout component; and a calculating device configured to calculate a disk shift amount on the basis of the relearned value and the original learned value corresponding to the relearned value, the disk shift amount representing a shift in a center of the disk from a rotation center of the spindle motor and from the center of the disk set during the manufacture of the disk drive, wherein the learned value contains a first order component of the runout component that is separated into a sine component and a cosine component such that the calculating device calculates the disk shift amount in accordance with the following relationship: d=α{(k sin 1−k sin 0) 2 +(k cos 1−k cos 0) 2 } 1/2 where: k sin 1 and k cos 1 represent the first order sine component and cosine component of the relearned value, respectively, k sin 0 and k cos 0 represent the first order sine component and cosine component of the original learned value, respectively, and α represents a proportional coefficient.