| US 7,333,280 B1 | ||
| Servo writing a disk drive by synchronizing a servo write clock to a reference pattern on the disk and compensating for repeatable phase error | ||
| Yakov M. Lifchits, San Jose, Calif. (US); Wing Ying, Fremont, Calif. (US); Yilin Cai, Fremont, Calif. (US); and Siri S. Weerasooriya, Campbell, Calif. (US) | ||
| Assigned to Western Digital Technologies, Inc., Lake Forest, Calif. (US) | ||
| Filed on Aug. 03, 2004, as Appl. No. 10/911,039. | ||
| This patent is subject to a terminal disclaimer. | ||
| Int. Cl. G11B 21/02 (2006.01) | ||
| U.S. Cl. 360—51 [360/75] | 16 Claims |
| 1. A method of writing product servo sectors on 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 coupled 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
reference pattern having a plurality of sync marks written around the disk, the method comprising the steps of:
(a) using the head internal to the disk drive to read the reference pattern to generate a read signal;
(b) detecting the sync marks from the read signal to generate a sync mark detect signal;
(c) generating a timing recovery measurement in response to the sync mark detect signal;
(d) generating a frequency control signal in response to the timing recovery measurement;
(e) generating a servo write clock in response to the frequency control signal;
(f) generating a feed-forward compensation value in response to the timing recovery measurement and the frequency control
signal;
(g) adjusting the timing recovery measurement in response to the feed-forward compensation value to compensate for a repeatable
phase error in the timing recovery measurement; and
(h) using the servo write clock and the head internal to the disk drive to write the product servo sectors to the disk.
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