Disk recording device for writing a radially coherent reference band by measuring relative timing offsets of reference bursts

• US 8,988,809 B1
• Filed: 02/18/2014
• Issued: 03/24/2015
• Est. Priority Date: 02/18/2014
• Status: Active Grant

• Current Assignee: JP Morgan Chase Bank, N.A. (JP Morgan Chase & Co)
• Original Assignee: Western Digital Corporation
• Inventors: Lin, Enhao
• Primary Examiner(s): Dinh, Tan X
• Application Number:
  US14/183,142
• Time in Patent Office: 399 Days
• Field of Search: None
• US Class Current: 360/52
• CPC Class Codes: G11B 5/59638 Servo formatting apparatuses, e.g. servo-writers
• CPC Class Codes: G11B 5/59666 Self servo writing

Abstract

A disk recording device is disclosed comprising a disk and a head. A first plurality of reference bursts are written along a first radius of the disk, the first plurality of reference bursts comprising a first reference burst. A second plurality of reference bursts are written along a second radius of the disk circumferentially offset from the first radius, the second plurality of reference bursts comprising a second reference burst. A first segment of a reference band is written along a third radius of the disk circumferentially offset from the second radius, and at a first timing offset from the first reference burst. A second timing offset between the first reference burst and the second reference burst is measured, and a second segment of the reference band is written radially coherent with the first segment based on the first timing offset and the second timing offset.

Claims

1. A disk recording device comprising:

a disk;

a head; and

control circuitry configured to;

write a first plurality of reference bursts along a first radius of the disk, the first plurality of reference bursts comprising a first reference burst;

write a second plurality of reference bursts along a second radius of the disk circumferentially offset from the first radius, the second plurality of reference bursts comprising a second reference burst;

write a first segment of a reference band along a third radius of the disk circumferentially offset from the second radius, and at a first timing offset from the first reference burst;

measure a second timing offset between the first reference burst and the second reference burst; and

write a second segment of the reference band radially coherent with the first segment based on the first timing offset and the second timing offset.

2. The disk recording device as recited in claim 1, wherein the first plurality of reference bursts are not radially coherent and the second plurality of reference bursts are not radially coherent.

3. The disk recording device as recited in claim 1, wherein the second reference burst is radially offset from the first reference burst by less than a width of the first reference burst.

4. The disk recording device as recited in claim 1, further comprising a write element, wherein a width of the first reference burst and a width of the second reference burst correspond to a width of the write element.

5. The disk recording device as recited in claim 1, wherein the control circuitry is further operable to:

write the first segment of the reference band during a first revolution of the disk;

measure the second timing offset during a second revolution of the disk; and

write the second segment of the reference band during a third revolution of the disk.

6. The disk recording device as recited in claim 1, wherein the control circuitry is further operable to:

write a third plurality of reference bursts along a fourth radius of the disk circumferentially offset from the first and second radius, the third plurality of reference bursts comprising a third reference burst;

measure a third timing offset between the second reference burst and the third reference burst; and

write the second segment of the reference band radially coherent with the first segment based on the first timing offset, the second timing offset, and the third timing offset.

7. The disk recording device as recited in claim 6, wherein the control circuitry is further operable to:

write the first segment of the reference band during a first revolution of the disk;

measure the second timing offset during the first revolution of the disk;

write the second segment of the reference band during a second revolution of the disk; and

measure the third timing offset during the second revolution of the disk.

8. The disk recording device as recited in claim 6, wherein the control circuitry is further operable to:

write a fourth plurality of reference bursts along a fifth radius of the disk circumferentially offset from the first, second and fourth radius, the fourth plurality of reference bursts comprising a fourth reference burst;

measure a fourth timing offset between the third reference burst and the fourth reference burst; and

write a third segment of the reference band radially coherent with the second segment based on the fourth timing offset.

9. The disk recording device as recited in claim 8, wherein the control circuitry is further operable to:

write the first segment of the reference band during a first revolution of the disk;

write the second segment of the reference band during a second revolution of the disk;

measure the fourth timing offset during the second revolution of the disk; and

write the third segment of the reference band during a third revolution of the disk.

10. The disk recording device as recited in claim 8, wherein the control circuitry is further operable to measure the second offset by measuring an interval as the disk rotates.

11. A method of operating disk recording device, the method comprising:

writing a first plurality of reference bursts along a first radius of the disk, the first plurality of reference bursts comprising a first reference burst;

writing a second plurality of reference bursts along a second radius of the disk circumferentially offset from the first radius, the second plurality of reference bursts comprising a second reference burst;

writing a first segment of a reference band along a third radius of the disk circumferentially offset from the second radius, and at a first timing offset from the first reference burst;

measuring a second timing offset between the first reference burst and the second reference burst; and

writing a second segment of the reference band radially coherent with the first segment based on the first timing offset and the second timing offset.

12. The method as recited in claim 11, wherein the first plurality of reference bursts are not radially coherent and the second plurality of reference bursts are not radially coherent.

13. The method as recited in claim 11, wherein the second reference burst is radially offset from the first reference burst by less than a width of the first reference burst.

14. The method as recited in claim 11, wherein a width of the first reference burst and a width of the second reference burst correspond to a width of the write element used to write the first reference burst and the second reference burst.

15. The method as recited in claim 11, further comprising:

writing the first segment of the reference band during a first revolution of the disk;

measuring the second timing offset during a second revolution of the disk; and

writing the second segment of the reference band during a third revolution of the disk.

16. The method as recited in claim 11, further comprising:

writing a third plurality of reference bursts along a fourth radius of the disk circumferentially offset from the first and second radius, the third plurality of reference bursts comprising a third reference burst;

measuring a third timing offset between the second reference burst and the third reference burst; and

writing the second segment of the reference band radially coherent with the first segment based on the first timing offset, the second timing offset, and the third timing offset.

17. The method as recited in claim 16, further comprising:

writing the first segment of the reference band during a first revolution of the disk;

measuring the second timing offset during the first revolution of the disk;

writing the second segment of the reference band during a second revolution of the disk; and

measuring the third timing offset during the second revolution of the disk.

18. The method as recited in claim 16, further comprising:

writing a fourth plurality of reference bursts along a fifth radius of the disk circumferentially offset from the first, second and fourth radius, the fourth plurality of reference bursts comprising a fourth reference burst;

measuring a fourth timing offset between the third reference burst and the fourth reference burst; and

writing a third segment of the reference band radially coherent with the second segment based on the fourth timing offset.

19. The method as recited in claim 18, further comprising:

writing the first segment of the reference band during a first revolution of the disk;

writing the second segment of the reference band during a second revolution of the disk;

measuring the fourth timing offset during the second revolution of the disk; and

writing the third segment of the reference band during a third revolution of the disk.

20. The method as recited in claim 18, further comprising measuring the second offset by measuring an interval as the disk rotates.