Method and apparatus to detect and mitigate contamination between a read/write head and a recording medium

Patent metadata

Field	Value
Publication number	US-9542963-B2
Application number	US-201514661522-A
Country	US
Kind code	B2
Filing date	Mar 18, 2015
Priority date	Mar 18, 2015
Publication date	Jan 10, 2017
Grant date	Jan 10, 2017

Abstract

A first adaptive fly height measurement is performed between a read/write head and a recording medium during a stage of qualification testing of a magnetic disk drive. A second adaptive fly height measurement of the read/write head is performed during a subsequent stage of the qualification testing. In response to determining that a fly height decrease between the first and second adaptive fly height measurements is above a threshold value, a mitigation operation is performed to remove a contaminant from a media-facing surface of the read/write head.

First claim

What is claimed is:

1. A method, comprising:
performing a first adaptive fly height measurement between a read/write head and a recording medium during a stage of qualification testing of a magnetic disk drive;
performing a second adaptive fly height measurement of the read/write head during a subsequent stage of the qualification testing; and
in response to determining that a fly height decrease between the first and second adaptive fly height measurements is above a threshold value, performing a mitigation operation to remove a contaminant from a media-facing surface of the read/write head.

2. The method of claim 1 , wherein the mitigation operation comprises:
defining an extra amount of power to be applied to a fly height actuator that controls an adaptive fly height of the read/write head, the extra amount of power sufficient to induce head-media contact without damaging the read/write head or the recording medium; and
applying the extra amount of power to the fly height actuator while the recording medium moves relative to the read/write head.

3. The method of claim 2 , wherein the extra amount of power is defined based on an amount of the fly height decrease.

4. The method of claim 2 , wherein the extra amount of power is applied while the read/write head is held over at least one track of the recording medium.

5. The method of claim 4 , wherein the at least one track comprises at least three tracks at an inner diameter, a middle diameter, and an outer diameter of the recording medium.

6. The method of claim 5 , wherein the amount of power is specific to each of the three tracks.

7. The method of claim 1 , wherein the first and second adaptive fly height measurements are taken over a plurality of zones of the recording medium, and wherein the fly height decrease is determined collectively over the plurality of zones.

8. The method of claim 1 , wherein if the fly height decrease is above a second threshold value, failing the magnetic disk drive without attempting the mitigation operation.

9. The method of claim 1 , further comprising after the mitigation operation:
performing at least the second adaptive fly height measurement of the read/write head a second time;
determining a second fly height decrease between the first adaptive fly height measurement and the second performance of the second adaptive fly height measurement; and
in response to the second fly height decrease being below the threshold value, passing the magnetic disk drive.

10. The method of claim 9 , further comprising failing the magnetic disk drive in response to the second fly height decrease being above a second threshold value.

11. A testing apparatus comprising:
an interface configured to communicate with a hard disk drive device; and
a processor coupled to the interface and configured to:
perform a first adaptive fly height measurement between a read/write head and a recording medium during a stage of qualification testing of a magnetic disk drive;
perform a second adaptive fly height measurement of the read/write head during a subsequent stage of the qualification testing; and
in response to determining that a fly height decrease between the first and second adaptive fly height measurements is above a threshold value, perform a mitigation operation to remove a contaminant from a media-facing surface of the read/write head.

12. The testing apparatus of claim 11 , wherein the mitigation operation comprises:
defining an extra amount of power to be applied to a fly height actuator that controls an adaptive fly height of the read/write head, the extra amount of power sufficient to induce head-media contact without damaging the read/write head or the recording medium; and
applying the extra amount of power to the fly height actuator while the recording medium moves relative to the read/write head.

13. The testing apparatus of claim 12 , wherein the extra amount of power is defined based on an amount of the fly height decrease.

14. The testing apparatus of claim 12 , wherein the extra amount of power is applied while the read/write head is held over at least one track of the recording medium.

15. The testing apparatus of claim 14 , wherein the at least one track comprises at least three tracks at an inner diameter, a middle diameter, and an outer diameter of the recording medium.

16. The testing apparatus of claim 15 , wherein the amount of power is specific to each of the three tracks.

17. The testing apparatus of claim 11 , wherein the first and second adaptive fly height measurements are taken over a plurality of zones of the recording medium, and wherein the fly height decrease is determined collectively over the plurality of zones.

18. The testing apparatus of claim 11 , wherein if the fly height decrease is above a second threshold value, failing the magnetic disk drive without attempting the mitigation operation.

19. The testing apparatus of claim 11 , wherein the processor is further configured to, after the mitigation operation:
perform at least the second adaptive fly height measurement of the read/write head a second time;
determine a second fly height decrease between the first adaptive fly height measurement and the second performance of the second adaptive fly height measurement; and
in response to the second fly height decrease being below the threshold value, pass the magnetic disk drive.

20. The testing apparatus of claim 19 , wherein the processor is further configured to fail the magnetic disk drive in response to the second fly height decrease being above a second threshold value.

Assignees

• Seagate Technology Llc

Inventors

• Zang Qun
• Amaria Meherab
• Lin Ying
• Jacobs Aaron
• Brown Daniel

Classifications

• G11B5/41 Primary

  Cleaning of heads {(of record carriers G11B23/50)} · CPC title

• G11B5/6029

  Measurement using values derived from the data signal read from the disk · CPC title

• G11B5/6076

  Detecting head-disk contact · CPC title

• G11B5/6011

  Control of flying height · CPC title

• G11B5/607

  using thermal means · CPC title