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

Claim 1

A method of positioning a read/write head of a magnetic data storage apparatus reading and/or writing an information data on and from a magnetic disk along a track defined thereon such that the read/write head is positioned exactly on the center of a desired track, comprising steps of: defining an inside reference track and an outside reference track on the magnetic disk, each of which having a predetermined track width and 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 said 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, said predetermined rotational angles being different in the inside reference track and in the outside reference track, and (c) a third servo control data further retarded from said 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; scanning the inside reference track and the outside reference track periodically each time a predetermined time interval has elapsed by the read/write head; reproducing the second and third servo control data by the read/write head; re-positioning the read/write head by moving the head such that the level of reproduced signals corresponding to the second servo control data and the third servo control data substantially coincide each other; obtaining an amount of offset in position of the read/write head when the read/write head is re-positioned in the re-positioning step, said amount of offset being the amount of movement of the read,,write head achieved in the re-positioning step; calculating another amount of offset for a desired track located between the inside and outside reference tracks on the basis cf the aforementioned offset for the inside reference track and the outside reference track; and correcting the position of the read/write head for the desired track by said amount of offset obtained in the calculating step.

Claim 2

A method of positioning a read/write head of a magnetic data storage apparatus reading and/or writing an information data on and from a magnetic disk along a track defined thereon such that the read/write head is positioned exactly on the center of a desired track, comprising steps of: defining an inside reference track and an outside reference track on the magnetic disk, each of which having a predetermined track width and 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 said 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, said predetermined rotational angles being different in the inside reference track and in the outside reference track, and (c) a third servo control data further retarded from said 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; scanning the inside reference track and the outside reference track periodically each time a predetermined time interval has elapsed by the read/write head; reproducing the second and third servo control data by the read/write head; re-positioning the read/write head by moving the head such that the level of reproduced signals corresponding to the second servo control data and the third servo control data substantially coincide each other; obtaining an amount of offset in position of the read/write head when the read/write head is re-positioned in the re-positioning step, said amount of offset being the amount of movement of the read,,write head achieved in the re-positioning step; calculating another amount of offset for a desired track located between the inside and outside reference tracks on the basis cf the aforementioned offset for the inside reference track and the outside reference track; and correcting the position of the read/write head for the desired track by said amount of offset obtained in the calculating step.