US 8,619,381 B2Granted

System and method for improving head positioning

AssigneeWD Media, LLC

InventorsAndreas Moser, Harold H. Gee, Steven E. Lambert, Dragos I. Mircea

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Abstract

Systems and methods for improving accuracy of head positioning using existing servo patterns are provided. In one embodiment, a method for improving read head positioning is provided that comprises: writing a series of tracks over a range of read offsets to be calibrated; measuring a set of raw track profiles from the series of tracks; sampling the set of raw track profiles at a series of signal amplitude levels; constructing a reference track profile from the set of sampled track profiles; calculating a set of read offset deltas from each sampled track profile; merging the sets of read offset deltas into a set of average read offset deltas; and converting the set of average read offset deltas into a read offset correction table. A similar method for improving disk write head positioning is also provided which utilizes such a read offset correction table to eventually create write offset correction table.

Claims30

Dependent claims

A method for calibrating a read offset for a read-write head, comprising:

writing a series of tracks onto a disk over a range of read offsets to be calibrated, wherein each track has a different offset with respect to a designated track on the disk;
measuring a set of raw track profiles from the series of tracks, wherein each track in the series of tracks has a corresponding raw track profile in the set of raw track profiles, and the corresponding raw track profile comprises a series of signal amplitude measurements acquired at uncorrected read offsets;
sampling the set of raw track profiles at a series of signal amplitude levels, thereby producing a set of sampled track profiles;
constructing a reference track profile from the set of sampled track profiles;
calculating a set of read offset deltas for each sampled track profile in the set of sampled track profiles, wherein each set of read offset deltas contains differences between the reference track profile and a sampled track profile in the set of raw track profiles;
merging the sets of read offset deltas into a set of average read offset deltas;
and
converting the set of average read offset deltas into a read offset correction table.

5 more elements

A method for calibrating a write offset for a read-write head, comprising:

writing a series of tracks on to a disk over a range of write offsets to be calibrated, wherein the series of tracks includes a reference track written at a predetermined offset, and wherein each track has a different offset with respect to a designated track on the disk;
measuring a set of raw track profiles from the series of tracks, wherein the set of raw track profiles includes a reference track profile for the reference track, and wherein each track in the series of tracks has a corresponding raw track profile in the set of raw track profiles, and the corresponding raw track profile comprises a series of signal amplitude measurements acquired at uncorrected read offsets;
correcting the set of raw track profiles using a read offset correction table, thereby producing a set of corrected track profiles;
sampling the set of corrected track profiles at a series of predetermined signal amplitude levels, thereby producing a set of sampled track profiles;
calculating a set of write offset deltas for each sampled track profile in the set of sampled track profiles, wherein each set of write offset deltas contains differences between the reference track profile and a sampled track profile in the set of sampled track profiles;
for each sampled track profile, averaging all the write offset deltas in the set of write offset deltas of the sampled track profile, thereby producing a set of corrected write offsets where each corrected write offset corresponds to a sampled track profile in the set of sampled track profiles;
and
converting the set of corrected write offsets into a write offset correction table.

5 more elements

Dependencies are inferred from the claim text.