Magnetic disk device and method for read/write offset error correction

摘要

A magnetic disk device according to an embodiment includes a head and a disk with a recording surface, the head including a reader configured to perform data reading, and a writer configured to write data. A method of correcting a read/write offset, according to the embodiment, is applied to the above magnetic disk device. This method includes reconstructing position data read by the reader, using a spline function, and correcting a read/write offset due to the distance between the writer and the reader, using the reconstructed position data.

主权项

1. A method of correcting a read/write offset, for a magnetic disk device including a head and a disk with a recording surface, the head including a reader configured to perform data reading, and a writer configured to write data, the method comprising:
reconstructing position data read by the reader, using a spline function; correcting a read/write offset due to a distance between the writer and the reader, using the reconstructed position data; estimating a track deviation from a position error signal; acquiring coefficients which define the spline function used to obtain a correction value of a read/write offset in each of tracks as position error measurement objects, using the estimated track deviation; providing each of servo sectors in each track with a target offset value which varies according to a sine wave path; measuring a position error signal obtained when the head is controlled to follow a target path that is obtained by adding the target offset value to a value assumed in each of widthwise central points of each track; processing the position error signal corresponding to each track, using a filter having inverse characteristics of a sensitivity function for a following control system; subtracting the target offset value in each servo sector; adding a value obtained by subtracting the target offset value in each servo sector, to a sum in each track of a track number obtained by adding the target offset value in each sector; and acquiring an estimated value by dividing the sum by a number of times of addition performed in each track.