Efficient feedforward compensation for repeatable runout in a disc drive
AssigneeSeagate Technology LLC
InventorsBrent Jay Harmer, Jianbo J. He, Khalil B. Dizaji, Hai Thanh Ho, Reed David Hanson
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Abstract
Method and apparatus for more accurate track following. Control circuitry rotates a data storage surface containing thousands of annular tracks. A “measured” subset of the tracks is selected so as to be interspersed with an “unmeasured” subset. The calibration profile is derived based on position error signals each obtained by reading from the measured subset and not from the unmeasured subset. Data from the unmeasured subset of tracks is ignored, in generating and/or updating the profile.
Claims30
A method of making a disc drive comprising steps of:
- (a) rotating a disc stack comprising at least one data storage surface having thousands of annular tracks, the thousands of tracks comprising first and second interspersed subsets thereof;
- (b) deriving a calibration profile for the data storage surface based on several position error signals each obtained by reading from the first subset and not by reading from the second subset;
- and
- (c) configuring the disc drive to use the calibration profile in a normal operating mode.
A disc drive comprising:
- a disc stack including at least one data storage surface having thousands of annular tracks, each track having several raw servo marks;
- and
- following means for using a calibration profile to follow a selected one of the tracks without reading any anti-follow adjustment factors from the selected track.
A disc drive comprising:
- a disc stack including at least one data storage surface having thousands of annular tracks, the thousands of tracks including first and second interspersed subsets thereof;
- and
- means for using a calibration profile derived from several position error signals each obtained by reading from the first subset and not by reading from the second subset.
Dependencies are inferred from the claim text.