Hitachi Global Storage Technologies Netherlands B.v.

Hgst Netherlands, B.v.

Indukumar Kalahasthi

Kris Victor Schouterden

Douglas Michael Zuercher

Quan-chiu Harry Lam

David H Jen

Christopher David Wiederholt

Joseph Silva

Guo Mian

Approaches for adjusting the recording density of a recording medium in a circumferential direction are disclosed. A hard-disk drive includes one or more electronic components configured to divide a track, of a plurality of concentric tracks on a magnetic-recording disk, into a plurality of portions, and write data to each of the plurality of portions at a recording density that is independent of the recording density used for any of the other portions. Data may be written to a first portion of a track at a different frequency than to a second portion of the same track. The frequency at which data is written may be adjusted for different portions of the same track to allow the frequency to be reduced at certain portions shown to have relatively higher soft error rate while increasing the frequency for other portions to achieve a desired average error rate for the track.

Adjusting recording density in a circumferential direction

A method is presented for writing data to a surface of a magnetic disk in a disk drive. The method includes determining a number of sector groups into which sectors of the data to be written will be grouped, loading registers with current values, kick-latching values, and precompensation values for each of said sector groups, and applying the current values, kick-latching values, and precompensation values for each of the sector groups to the write head while writing data to the sector groups of the recording media.

Method for precompensation/write-current latching to improve error rate

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San Jose, CA, United States of America

Indukumar Kalahasthi