US 7,212,364 B1Granted

Servo writing a disk drive by synchronizing a servo write clock in response to a sync mark reliability metric

AssigneeWestern Digital Technologies, Inc.

InventorTehri S. Lee

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Abstract

A method of writing product servo sectors to a disk of a disk drive is disclosed. A plurality of spiral tracks are written to the disk, wherein each spiral track comprises a high frequency signal interrupted at a predetermined interval by a sync mark. During the product servo writing process, the sync marks in the spiral tracks are detected and a sync mark reliability metric is generated, wherein the sync mark reliability metric represents a probability that the sync mark was detected accurately. A timing recovery measurement is generated in response to the detected sync marks and the sync mark reliability metrics. A servo write clock is synchronized in response to the timing recovery measurement and used to write the product servo sectors to the disk while serving on the spiral tracks.

Claims10

Dependent claims

A method of writing product servo sectors to a disk of a disk drive, the disk drive comprising control circuitry and a head disk assembly (HDA) comprising the disk, an actuator arm, a head connected to a distal end of the actuator arm, and a voice coil motor for rotating the actuator arm about a pivot to position the head radially over the disk, the disk comprising a plurality of spiral tracks, wherein each spiral track comprises a high frequency signal interrupted at a predetermined interval by a sync mark, the method comprising the steps of:

(a) using the head internal to the disk drive to read the spiral tracks to generate a read signal;
(b) processing the read signal to detect a sync mark in a spiral track and generating an associated sync mark reliability metric, the sync mark reliability metric representing a probability that the sync mark was detected accurately;
(c) generating a timing recovery measurement in response to the detected sync mark and the sync mark reliability metric;
(d) synchronizing a servo write clock in response to the timing recovery measurement;
(e) processing the read signal representing the high frequency signal in the spiral track to generate a position error signal (PES) used to maintain the head along a substantially circular target path;
and
(f) using the servo write clock and the head internal to the disk drive to write the product servo sectors along the circular target path.

4 more elements

(a) using the head internal to the disk drive to read the spiral tracks to generate a read signal;
(b) processing the read signal to detect a sync mark in a spiral track and generating an associated sync mark reliability metric, the sync mark reliability metric representing a probability that the sync mark was detected accurately;
(c) generating a timimg recovery measurement in response to the detected sync mark and the sync mark relaibility metric;
(d) synchronizing a servo write clock in response to the timing recovery measurement;
(e) processing the read signal representing the high frequency signal in the spiral track to generate a position error signal (PES) used to maintain the head along a substantially circular target path;
and
(f) using the servo write clock and the head internal to the disk drive to write the product servo sectors along the circular target path wherein the step of generating the timing recovery measurement comprises the steps of:
(i) comparing the sync mark reliability metric to a threshold;
(ii) if the sync mark reliability metric is above the threshold, generating the timing recovery measurement in response to the detected sync mark;
(iii) if the sync mark reliability metric is below the threshold, ignoring the detected sync mark,
(iv) accumulating the consecutive number of ignored sync marks;
and
(v) if the accumulation exceeds a predetermined number and the sync mark reliability metric is below the threshold, generating the timing recovery measurement in response to the detected sync mark.

10 more elements

A disk drive comprising:

(a) a disk comprising a plurality of spiral tracks, wherein each spiral track comprises a high frequency signal interrupted at a predetermined interval by a sync mark;
(b) an actuator arm;
(c) a head connected to a distal end of the actuator arm;
(d) a voice coil motor for rotating the actuator arm about a pivot to position the head radially over the disk;
and
(e) control circuitry for writing a plurality of product servo sectors to the disk to
define a plurality of radially spaced, concentric data tracks by:
using the head internal to the disk drive to read the spiral tracks to generate a read signal;
processing the read signal to detect a sync mark in a spiral track and generating an associated sync mark reliability metric, the sync mark reliability metric representing a probability that the sync mark was detected accurately;
generating a timing recovery measurement in response to the detected sync mark and the sync mark reliability metric;
synchronizing a servo write clock in response to the timing recovery measurement;
processing the read signal to representing the high frequency signal in the spiral track to generate a position error signal used to maintain the head along a substantially circular target path;
and
using the servo write clock and the head internal to the disk drive to write the product servo sectors along the circular target path.

11 more elements

A disk drive comprising:

(a) a disk comprising a plurality of spiral tracks, wherein each spiral track comprises a high frequency signal interrupted at a predetermined interval by a sync mark;
(b) an actuator arm;
(c) a head connected to a distal end of the actuator arm;
(d) a voice coil motor for rotating the actuator arm about a pivot to position the head radially over the disk;
and
(e) control circuitry for writing a plurality of product servo sectors to the disk to define a plurality of radially spaced, concentric data tracks by;
using the head internal to the disk drive to read the spiral tracks to generate a read signal;
processing the read signal to detect a sync mark in a spiral track and generating an associated sync mark reliability metric, the sync mark reliability metric representing a probability that the sync mark was detected accurately;
generating a timing recovery measurement in response to the detected sync mark and the sync mark reliability metric;
synchronizing a servo write clock in response to the timing recovery measurement;
processing the read signal to representing the high frequency signal in the spiral track to generate a position error signal used to maintain the head along a substantially circular target path;
and
using the servo write clock and the head internal to the disk drive to write the product servo sectors along the circular target path wherein the control circuitry for generates the timing recovery measurement for writing the plurality of product servo sectors by:
(i) comparing the sync mark reliability metric to a threshold;
(ii) if the sync mark reliability metric is above the threshold, generating the timing recovery measurement in response to the detected sync mark;
(iii) if the sync mark reliability metric is below the threshold, ignoring the detected sync mark
(iv) accumulating the consecutive number of ignored sync marks;
and
(v) if the accumulation exceeds a predetermined number and the sync mark reliability metric is below the threshold, generating the timing recovery measurement in response to the detected sync mark.

16 more elements

Dependencies are inferred from the claim text.