Disk drive employing overlapping servo zones to facilitate servo zone crossing
View Patent ↗A disk drive is disclosed comprising a head actuated over a disk, the disk comprising a plurality of servo sectors defining a plurality of servo tracks, wherein the servo tracks form a plurality of servo zones. A servo data rate of servo sectors in a first servo zone is different than a servo data rate of servo sectors in a second servo zone. A boundary of a first servo zone overlaps with a boundary of a second servo zone over a transition zone. The servo sectors of the first servo zone are interleaved with the servo sectors of the second servo zone within the transition zone. At least one servo parameter is adjusted when the head is over the transition zone in order to transition between the first servo zone and the second servo zone.
1. A disk drive comprising:
a disk comprising a plurality of servo sectors defining a plurality of servo tracks, wherein:
the servo tracks form a plurality of servo zones;
a servo data rate of servo sectors in a first servo zone is different than a servo data rate of servo sectors in a second servo zone;
a boundary of a first servo zone overlaps with a boundary of a second servo zone over a transition zone; and
the servo sectors of the first servo zone are interleaved with the servo sectors of the second servo zone within the transition zone;
a head actuated radially over the disk; and
control circuitry operable to adjust at least one servo parameter when the head is over the transition zone in order to transition between the first servo zone and the second servo zone.
2. The disk drive as recited in claim 1 , wherein:
the head comprises a read element and a write element separated by a radial offset; and
the transition zone is at least as wide as the radial offset.
3. The disk drive as recited in claim 1 , wherein the servo sectors of the first servo zone are offset circumferentially from the servo sectors of the second servo zone.
4. The disk drive as recited in claim 1 , wherein the servo parameter comprises a servo gate that times a circumferential location of the servo sectors.
5. The disk drive as recited in claim 1 , wherein the servo parameter comprises a sync window that times a circumferential location of a sync mark within the servo sectors.
6. The disk drive as recited in claim 1 , wherein the servo parameter comprises a center frequency for a timing control loop that synchronizes a disk locked clock to the servo data rate of the servo sectors.
7. The disk drive as recited in claim 1 , wherein the control circuitry is further operable to:
define a plurality of data tracks on the disk relative to the servo tracks;
write user data to data tracks outside the transition zone; and
not write user data within at least part of the transition zone.
8. The disk drive as recited in claim 1 , wherein:
the head comprises a read element and a write element substantially wider than the read element; and
the transition zone is at least as wide as the write element.
9. A disk drive comprising:
a disk;
a head actuated radially over the disk; and
control circuitry operable to:
write first servo sectors in a first radial direction to define servo tracks from a first diameter of the disk to substantially a middle diameter of the disk;
write second servo sectors in a second radial direction opposite the first radial direction to define servo tracks from a second diameter of the disk toward the middle diameter of the disk, wherein:
a boundary of the first servo sectors overlaps with a boundary of the second servo sectors over a transition zone; and
the first servo sectors are interleaved with the second servo sectors within the transition zone.
10. The disk drive as recited in claim 9 , wherein a servo data rate of the first servo sectors is different than a servo data rate of the second servo sectors.
11. The disk drive as recited in claim 9 , wherein a servo data rate of the first servo sectors is substantially the same as a servo data rate of the second servo sectors.
12. A method of operating a disk drive, the disk drive comprising a head actuated over a disk comprising a plurality of servo sectors defining a plurality of servo tracks, wherein:
the servo tracks form a plurality of servo zones;
a servo data rate of servo sectors in a first servo zone is different than a servo data rate of servo sectors in a second servo zone;
a boundary of a first servo zone overlaps with a boundary of a second servo zone over a transition zone; and
the servo sectors of the first servo zone are interleaved with the servo sectors of the second servo zone within the transition zone;
the method comprising adjusting at least one servo parameter when the head is over the transition zone in order to transition between the first servo zone and the second servo zone.
13. The method as recited in claim 12 , wherein:
the head comprises a read element and a write element separated by a radial offset; and
the transition zone is at least as wide as the radial offset.
14. The method as recited in claim 12 , wherein the servo sectors of the first servo zone are offset circumferentially from the servo sectors of the second servo zone.
15. The method as recited in claim 12 , wherein the servo parameter comprises a servo gate that times a circumferential location of the servo sectors.
16. The method as recited in claim 12 , wherein the servo parameter comprises a sync window that times a circumferential location of a sync mark within the servo sectors.
17. The method as recited in claim 12 , wherein the servo parameter comprises a center frequency for a timing control loop that synchronizes a disk locked clock to the servo data rate of the servo sectors.
18. The method as recited in claim 12 , further comprising:
defining a plurality of data tracks on the disk relative to the servo tracks;
writing user data to data tracks outside the transition zone; and
not writing user data within at least part of the transition zone.
19. A method of operating a disk drive, the disk drive comprising a head actuated over a disk, the method comprising:
writing first servo sectors in a first radial direction to define servo tracks from a first diameter of the disk to substantially a middle diameter of the disk;
writing second servo sectors in a second radial direction opposite the first radial direction to define servo tracks from a second diameter of the disk toward the middle diameter of the disk, wherein:
a boundary of the first servo sectors overlaps with a boundary of the second servo sectors over a transition zone; and
the first servo sectors are interleaved with the second servo sectors within the transition zone.
20. The method as recited in claim 19 , wherein a servo data rate of the first servo sectors is different than a servo data rate of the second servo sectors.
21. The method as recited in claim 19 , wherein a servo data rate of the first servo sectors is substantially the same as a servo data rate of the second servo sectors.
22. The method as recited in claim 19 , wherein:
the head comprises a read element and a write element substantially wider than the read element; and
the transition zone is at least as wide as the write element.