Magnetic duplication for precise servo writing on magnetic disks

A servo pattern of a 20 Gbit/in/sup 2/ level was directly duplicated on hard disks by using a magnetic duplication method, and the accuracy of the signal and the following performance on the duplicated servo pattern were evaluated. The phase servo pattern was composed of straight lines and was lithographically formed on a mastering disk. The period accuracy of the readback signal was very high. The repeatable position error for adjacent tracks in a prototype drive was measured, and the difference between two adjacent RPE trajectories was sufficiently small. The magnetic duplication method showed the possibility of precise servo-track writing for high-density hard disk drives.