Patent ID: 6967799
Filing Date: 2005-11-22
Classification: G11B

Abstract:
1. 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 with sync mark detection circuitry to detect the sync marks in the spiral tracks; (c) generating a time-stamped sync mark detect signal when one of the sync marks is detected, wherein the time-stamped sync mark detect signal represents a time when the sync mark was detected relative to a servo write clock; (d) computing in firmware a difference between the time-stamped sync mark detect signal and an expected time to thereby generate a coarse timing recovery measurement used to synchronize the servo write clock; and (e) using the servo write clock and the head internal to the disk drive to write the product servo sectors along a substantially circular target path.