Data storage device measuring laser protrusion fly height profile

• US 9,153,266 B1
• Filed: 09/11/2014
• Issued: 10/06/2015
• Est. Priority Date: 09/11/2014
• Status: Active Grant

• Current Assignee: JP Morgan Chase Bank, N.A. (JP Morgan Chase & Co)
• Original Assignee: Western Digital Technologies Incorporated (Western Digital Corporation)
• Inventors: Chia, Galvin T., Giovenzana, Davide, Yeo, Teik Ee
• Primary Examiner(s): Sniezek, Andrew L
• Application Number:
  US14/483,397
• Time in Patent Office: 390 Days
• Field of Search: None
• US Class Current: 1/1
• CPC Class Codes: G11B 11/10515 Reproducing compensating pit shift G11B11/1053
• CPC Class Codes: G11B 2005/0021 Thermally assisted recording using an auxiliary energy source for heating the recording layer locally to assist the magnetization reversal
• CPC Class Codes: G11B 5/6052 using optical means
• CPC Class Codes: G11B 5/607 using thermal means

Abstract

A data storage device is disclosed comprising a disk comprising a plurality of tracks, where each track comprises a plurality of servo sectors and at least one data segment between consecutive servo sectors. The data storage device further comprises a head actuated over the disk, the head comprising a laser configured to heat the disk during write operations based on a laser power. During a first revolution of the disk, the laser power is first increased over a first interval to cause at least part of the head to protrude toward a first data segment of the disk. After the first interval, the laser power is decreased and a fly height pattern is read from the first data segment to first measure a fly height of the head.

Claims

1. A data storage device comprising:

a disk comprising a plurality of tracks, where each track comprises a plurality of servo sectors and at least one data segment between consecutive servo sectors;

a head actuated over the disk, the head comprising a laser configured to heat the disk during write operations based on a laser power; and

control circuitry configured during a first revolution of the disk to;

first increase the laser power over a first interval to cause at least part of the head to protrude toward a first data segment of the disk; and

after the first interval, first decrease the laser power and read a fly height pattern from the first data segment to first measure a fly height of the head.

2. The data storage device as recited in claim 1, wherein the increased laser power corresponds to a write laser power.

3. The data storage device as recited in claim 2, wherein the control circuitry is further configured to write data to the first data segment during the first interval.

4. The data storage device as recited in claim 1, wherein the head further comprises a fly height actuator and the control circuitry is further configured to adjust a control signal applied to the fly height actuator in connection with increasing the laser power.

5. The data storage device as recited in claim 1, wherein after first measuring the fly height of the head the control circuitry is further configured to:

second increase the laser power over a second interval different from the first interval to cause at least part of the head to protrude toward a second data segment of the disk; and

after the second interval, second decrease the laser power and read a fly height pattern from the second data segment to second measure a fly height of the head.

6. The data storage device as recited in claim 5, wherein the second data segment comprises the first data segment.

7. The data storage device as recited in claim 5, wherein the control circuitry is further configured to second increase the laser power, second decrease the laser power and second measure the fly height during the first revolution of the disk.

8. The data storage device as recited in claim 5, wherein the control circuitry is further configured to second increase the laser power, second decrease the laser power and second measure the fly height during a second revolution of the disk.

9. The data storage device as recited in claim 5, wherein:

the first measured fly height corresponds to a first data point of a protrusion fly height profile at the beginning of the write operations; and

the second measured fly height corresponds to a second data point of the protrusion fly height profile.

10. The data storage device as recited in claim 1, wherein:

each servo sector comprises a servo preamble recorded at a first frequency; and

the fly height pattern comprises a second frequency different from the first frequency.

11. A method of operating a data storage device, the method comprising during a first revolution of a disk:

first increasing a laser power of a head over a first interval to cause at least part of the head to protrude toward a first data segment between consecutive servo sectors of the disk; and

after the first interval, first decreasing the laser power and reading a fly height pattern from the first data segment to first measure a fly height of the head.

12. The method as recited in claim 11, wherein the increased laser power corresponds to a write laser power.

13. The method as recited in claim 12, further comprising writing data to the first data segment during the first interval.

14. The method as recited in claim 11, further comprising adjusting a control signal applied to a fly height actuator in connection with increasing the laser power.

15. The method as recited in claim 11, wherein after first measuring the fly height of the head the method further comprises:

second increasing the laser power over a second interval different from the first interval to cause at least part of the head to protrude toward a second data segment of the disk; and

after the second interval, second decreasing the laser power and read a fly height pattern from the second data segment to second measure a fly height of the head.

16. The method as recited in claim 15, wherein the second data segment comprises the first data segment.

17. The method as recited in claim 15, further comprising second increasing the laser power, second decreasing the laser power and second measuring the fly height during the first revolution of the disk.

18. The method as recited in claim 15, further comprising second increasing the laser power, second decrease the laser power and second measure the fly height during a second revolution of the disk.

19. The method as recited in claim 15, wherein:

the first measured fly height corresponds to a first data point of a protrusion fly height profile at the beginning of the write operations; and

the second measured fly height corresponds to a second data point of the protrusion fly height profile.

20. The method as recited in claim 11, wherein:

each servo sector comprises a servo preamble recorded at a first frequency; and

the fly height pattern comprises a second frequency different from the first frequency.