Method for centering a read/write head of a magnetic data storage apparatus on a track of a magnetic disk

摘要

A method of centering a read/write head of a magnetic data storage apparatus on a desired track comprises steps of defining an inside reference track and an outside reference track on the magnetic disk, each of which being recorded with (a) a first servo control data at a center thereof, (b) a second servo control data retarded in time corresponding to a predetermined rotational angle of the disk with respect to the first data at a position offset towards either one of the inner side of the disk and the outer side of the disk by a half width of the track, the predetermined rotational angles being different in the inside reference track and the outside reference track, and (c) a third servo control data retarded from the second data at a position offset towards the other one of the inner side of the disk and the outer side of the disk by a half width of the track. The center of the track is detected by comparing levels of reproduced second and third servo control data, and the position of the head is corrected accordingly. Such a correction is repeated periodically.