Patent ID: 6965489

Claim:
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 method comprising the steps of: (a) inserting a head positioning pin of an external spiral servo writer into the HDA, the head positioning pin for engaging the actuator arm; (b) using the external spiral servo writer to derive a radial location of the head; (c) actuating the head positioning pin in response to the radial location of the head in a closed loop system to rotate the actuator arm about the pivot in order to position the head radially over the disk while: writing a plurality of reference servo sectors in a substantially circular reference path, each reference servo sector comprising a sync mark and a plurality of servo bursts; and writing a plurality of spiral tracks, each spiral track comprising a high frequency signal interrupted at a predetermined interval by a sync mark; (d) removing the head positioning pin from the HDA; (e) synchronizing a servo write clock by: using the head internal to the disk drive to read the servo bursts in the reference servo sectors to generate a position error signal used to maintain the head along the circular reference path; using the head internal to the disk drive to read the sync marks in the reference servo sectors to generate a reference sync mark detect signal; and synchronizing the servo write clock in response to the reference sync mark detect signal; and (f) writing the 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 high frequency signal in the spiral tracks to generate a position error signal used to maintain the head along a substantially circular target path; 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; maintaining synchronization of the servo write clock in response to the spiral sync mark detect signal; 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.