US 6,943,978 B1Granted

Servo writing a disk drive by synchronizing a servo write clock to a high frequency signal in a spiral track

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 read to generate a coarse timing recovery measurement, and the high frequency signal in the spiral tracks is read to generate a fine timing recovery measurement. The coarse and fine timing recovery measurements are processed to synchronize a servo write clock used to write the product servo sectors to the disk. In one embodiment the control circuitry within the disk drive synchronizes the servo write clock by reading the spiral tracks, and in an alternative embodiment an external product servo writer synchronizes the servo write clock by reading the spiral tracks.

Claims14

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 high frequency signal in the spiral tracks to generate a position error signal used to maintain the head along a substantially circular target path;
(b) using the head internal to the disk drive to read the sync marks in the spiral tracks to generate a spiral sync mark detect signal;
(c) generating a coarse timing recovery measurement in response to the spiral sync mark detect signal;
(d) generating a fine timing recovery measurement in response to the high frequency signal in the spiral tracks;
(e) synchronizing a servo write clock in response to the coarse timing recovery measurement and the fine timing recovery measurement;
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

Dependencies are inferred from the claim text.