Hard disk drive servo technology for media-level servo track writing

Hard disk drive (HDD) servo technology for media-level servo track writing (MLSTW) is developed. MLSTW is the process of writing servo signals on magnetic disks before they are assembled in drives. It supplies a solution to achieve low-cost and accurate means of servo-signal writing. The HDD servo controller for MLSTW drives compensates for radial and rotational distortions of the servo signals (e.g., track-address, eccentricities, and servo-signal timing) that are inherent in the MLSTW method. The authors prove that the positioning accuracy is improved and the seek time is unchanged by using the new servo controller for HDDs with MLSTW disks. Index Terms--Calibration, delay effects, disk drives, distortion, feedforward systems, magnetic disk recording, position control, STW.