Demodulation of servo tracking signals printed with a lithographically patterned master disk

Demodulation of the servo tracking signals magnetically printed on hard disks by using a lithographically patterned master disk has been studied. Position signal decoded from the printed servo pattern was successfully demonstrated on a spin stand. Position error evaluated in a prototype drive was 30% track pitch. Pulse timing shift control by compensating the pattern dimension, and introduction of a more sophisticated servo control system for actively controlling the printed pattern eccentricity would be key issues for further improvements.