Granted Patent B1

US 8,953,271 · App. 13/928,845 · Granted Feb 10, 2015

Abstract

Claims (63)

1. A disk drive comprising:

a disk comprising a plurality of servo tracks, wherein each servo track comprises a plurality of servo sectors;

a head actuated over the disk; and

control circuitry operable to:

define a plurality of zones, wherein each zone comprises a plurality of the servo tracks;

generate a metric for each zone;

when the metric for a first zone exceeds a first threshold, generate feedback compensation values for at least two servo tracks, wherein the feedback compensation values compensate for a written-in error of the servo sectors of each servo track;

when the metric for a second zone does not exceed the first threshold, skip generating feedback compensation values for the second zone;

generate a position error signal (PES) representing a difference between a measured position of the head and a target position;

generate a repeatable disturbance for each of a plurality of tracks in each zone based on the PES; and

generate the metric for each zone as an average magnitude of the repeatable disturbance generated for the plurality of tracks.

2. The disk drive as recited in claim 1 , wherein the control circuitry is further operable to write the feedback compensation values generated for each servo track to each servo track.

3. The disk drive as recited in claim 1 , wherein the control circuitry is further operable to:

average the metrics generated for the zones to generate an average metric; and

when the metric for the second zone does not exceed the first threshold and the average metric exceeds a second threshold, generate feedback compensation values for the second zone.

4. A method of operating a disk drive comprising a head actuated over a disk comprising a plurality of servo tracks, wherein each servo track comprises a plurality of servo sectors, the method comprising:

defining a plurality of zones, wherein each zone comprises a plurality of the servo tracks;

generating a metric for each zone;

when the metric for a first zone exceeds a first threshold, generating feedback compensation values for at least two servo tracks, wherein the feedback compensation values compensate for a written-in error of the servo sectors of each servo track;

when the metric for a second zone does not exceed the first threshold, skipping generating feedback compensation values for the second zone;

generating a position error signal (PES) representing a difference between a measured position of the head and a target position;

generating a repeatable disturbance for each of a plurality of tracks in each zone based on the PES; and

generating the metric for each zone as an average magnitude of the repeatable disturbance generated for the plurality of tracks.

5. The method as recited in claim 4 , further comprising writing the feedback compensation values generated for each servo track to each servo track.

6. The method as recited in claim 4 , further comprising:

averaging the metrics generated for the zones to generate an average metric; and

when the metric for the second zone does not exceed the first threshold and the average metric exceeds a second threshold, generating feedback compensation values for the second zone.

7. A disk drive comprising:

a disk comprising a plurality of servo tracks, wherein each servo track comprises a plurality of servo sectors;

a head actuated over the disk; and

control circuitry operable to:

define a plurality of zones, wherein each zone comprises a plurality of the servo tracks;

generate a metric for each zone;

when the metric for a first zone exceeds a first threshold, generate feedback compensation values for at least two servo tracks, wherein the feedback compensation values compensate for a written-in error of the servo sectors of each servo track;

when the metric for a second zone does not exceed the first threshold, skip generating feedback compensation values for the second zone;

generate a position error signal (PES) representing a difference between a measured position of the head and a target position;

generate a non-repeatable disturbance for each of a plurality of tracks in each zone based on the PES; and

generate the metric for each zone as an average magnitude of the non-repeatable disturbance generated for the plurality of tracks.

8. A method of operating a disk drive comprising a head actuated over a disk comprising a plurality of servo tracks, wherein each servo track comprises a plurality of servo sectors, the method comprising:

defining a plurality of zones, wherein each zone comprises a plurality of the servo tracks;

generating a metric for each zone;

when the metric for a first zone exceeds a first threshold, generating feedback compensation values for at least two servo tracks, wherein the feedback compensation values compensate for a written-in error of the servo sectors of each servo track;

when the metric for a second zone does not exceed the first threshold, skipping generating feedback compensation values for the second zone;

generating a position error signal (PES) representing a difference between a measured position of the head and a target position;

generating a non-repeatable disturbance for each of a plurality of tracks in each zone based on the PES; and

generating the metric for each zone as an average magnitude of the non-repeatable disturbance generated for the plurality of tracks.

9. A disk drive comprising:

a disk comprising a plurality of servo tracks, wherein each servo track comprises a plurality of servo sectors;

a head actuated over the disk; and

control circuitry operable to:

define a plurality of zones, wherein each zone comprises a plurality of the servo tracks;

generate a metric for each zone;

when the metric for a first zone exceeds a first threshold, generate feedback compensation values for at least two servo tracks, wherein the feedback compensation values compensate for a written-in error of the servo sectors of each servo track;

when the metric for a second zone does not exceed the first threshold, skip generating feedback compensation values for the second zone;

average the metrics generated for the zones to generate an average metric; and

when the metric for the second zone does not exceed the first threshold and the average metric exceeds a second threshold, generate feedback compensation values for the second zone.

10. A method of operating a disk drive comprising a head actuated over a disk comprising a plurality of servo tracks, wherein each servo track comprises a plurality of servo sectors, the method comprising:

defining a plurality of zones, wherein each zone comprises a plurality of the servo tracks;

generating a metric for each zone;

when the metric for a first zone exceeds a first threshold, generating feedback compensation values for at least two servo tracks, wherein the feedback compensation values compensate for a written-in error of the servo sectors of each servo track;

when the metric for a second zone does not exceed the first threshold, skipping generating feedback compensation values for the second zone;

averaging the metrics generated for the zones to generate an average metric; and

when the metric for the second zone does not exceed the first threshold and the average metric exceeds a second threshold, generating feedback compensation values for the second zone.

Assignments (7)