Electronic system with head management mechanism and method of operation thereof

• US 9,842,617 B1
• Filed: 06/29/2015
• Issued: 12/12/2017
• Est. Priority Date: 06/29/2015
• 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: Haralson, Phillip Scott, Chia, Galvin T. P., Vasquez, Steven R., McDaniel, Mark
• Primary Examiner(s): Pendleton, Dionne H
• Application Number:
  US14/754,340
• Time in Patent Office: 897 Days
• 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 5/6011 Control of flying height
• CPC Class Codes: G11B 5/6029 Measurement using values derived from the data signal read from the disk
• CPC Class Codes: G11B 5/607 using thermal means

Abstract

An apparatus includes: a media; a heat assisted magnetic recording (HAMR) head over the media; and control circuitry, coupled to the HAMR head, the control circuitry being configured to: receive a write command to write the media; apply a dynamic flying height (DFH) control before asserting a write gate of the HAMR head; assert the write gate to the HAMR head; and enable a flying height compensation mechanism to maintain a constant value of a flying height of the HAMR head over the media during a next assertion of the write gate.

Claims

1. An apparatus comprising:

a media;

a heat assisted magnetic recording (HAMR) head over the media; and

control circuitry, coupled to the HAMR head, the control circuitry being configured to;

receive a write command to write the media;

apply a dynamic flying height (DFH) control before asserting a write gate of the HAMR head;

assert the write gate to the HAMR head; and

enable a flying height compensation mechanism to maintain a constant value of a flying height of the HAMR head over the media during a next assertion of the write gate, the flight height compensation mechanism maintaining a history of write gate information to adjust the DFH control.

2. The apparatus as claimed in claim 1 wherein the flying height compensation mechanism comprises a control to control a timing of a new write operation with the HAMR head.

3. The apparatus as claimed in claim 1 wherein the control circuitry is further configured to schedule the DFH control at a specified time from an end of a servo gate.

4. The apparatus as claimed in claim 1 wherein the flying height compensation mechanism comprises, prior to the next assertion of the write gate, applying the DFH control based on a size of a protrusion on the HAMR head from the assertion of the write gate.

5. The apparatus as claimed in claim 1 wherein the flying height compensation mechanism comprises, prior to the next assertion of the write gate, applying the DFH control based on a duration of the assertion of the write gate.

6. The apparatus as claimed in claim 1 wherein the flying height compensation mechanism comprises maintaining a history register of a count of the assertions of the write gate to adjust the DFH control.

7. The apparatus as claimed in claim 1 wherein the control circuitry is further configured to store values of the DFH control, for the write command, in a command execution memory.

8. The apparatus as claimed in claim 1 wherein the control circuitry is further configured to detect a skip mask or a media error to adjust the DFH control.

9. The apparatus as claimed in claim 1 wherein the control circuitry is further configured to monitor a closed loop circuit to measure the flying height while writing.

10. The apparatus as claimed in claim 1 wherein the control circuitry is further configured to establish a complex trigger to transfer the DFH control to a preamplifier.

11. The apparatus as claimed in claim 1 wherein the control circuitry is further configured to reorder execution of the write command including the DFH control selected for the write command.

12. The apparatus as claimed in claim 1 wherein the flying height compensation mechanism comprises a controller coupled to a preamplifier, a head-media space (HMS) detector and a DFH control in the HAMR head managed by the controller.

13. The apparatus as claimed in claim 1 further comprising a DFH timer configured to monitor the update of a preamplifier serial port, to detect a set-up exception and a write fault error.

14. A method of operating an apparatus, the method comprising:

receiving a write command for writing a media;

applying a dynamic flying height (DFH) control to a heat assisted magnetic recording (HAMR) head;

asserting a write gate to the HAMR head; and

enabling a flying height compensation mechanism for maintaining a constant value of a flying height of the HAMR head over the media during a next assertion of the write gate, the flight height compensation mechanism maintaining a history of write gate information to adjust the DFH control.

15. The method as claimed in claim 14 wherein enabling the flying height compensation mechanism comprises enabling a control for controlling a timing of a new write operation with the HAMR head.

16. The method as claimed in claim 14 further comprising scheduling the DFH control at a specified time from an end of a servo gate.

17. The method as claimed in claim 14 wherein enabling the flying height compensation mechanism comprises applying the DFH control, based on a size of a protrusion on the HAMR head from the assertion of the write gate, prior to the next assertion of the write gate.

18. The method as claimed in claim 14 wherein enabling the flying height compensation mechanism comprises applying the DFH control, based on a duration of the assertion of the write gate, prior to the next assertion of the write gate.

19. The method as claimed in claim 14 wherein enabling the flying height compensation mechanism comprises maintaining a history register of a count of the assertions of the write gate to adjust the DFH control.

20. The method as claimed in claim 14 further comprising storing values of the DFH control, for the write command, in a command execution memory.

21. The method as claimed in claim 14 further comprising detecting a skip mask or a media error for adjusting the DFH control.

22. The method as claimed in claim 14 further comprising monitoring a closed loop circuit to measure the flying height while writing.

23. The method as claimed in claim 14 further comprising establishing a complex trigger for transferring the DFH control to a preamplifier.

24. The method as claimed in claim 14 further comprising reordering execution of the write command including selecting the DFH control for the write command.

25. The method as claimed in claim 14 wherein enabling the flying height compensation mechanism includes managing a DFH control for controlling a protrusion on the HAMR head and monitoring a head-media space (HMS) detector for actively measuring a flying height of the HAMR head.

26. The method as claimed in claim 14 further comprising detecting a write fault, during the next assertion of the write gate, by a DFH timer for detecting a set-up exception of a preamplifier serial port.

27. An apparatus comprising:

control circuitry, configured to be coupled to a heat assisted magnetic recording (HAMR) head that is over a media, the control circuitry being configured to;

receive a write command to write the media;

apply a dynamic flying height (DFH) control before asserting a write gate of the HAMR head;

assert the write gate to the HAMR head; and

enable a flying height compensation mechanism to maintain a constant value of a flying height of the HAMR head over the media during a next assertion of the write gate, the flight height compensation mechanism maintaining a history of write gate information to adjust the DFH control.

28. The apparatus as claimed in claim 27 wherein the flying height compensation mechanism comprises a control to control a timing of a new write operation with the HAMR head.

29. The apparatus as claimed in claim 27 wherein the control circuitry is further configured to schedule the DFH control at a specified time from an end of a servo gate.

30. The apparatus as claimed in claim 27 wherein the flying height compensation mechanism comprises, prior to the next assertion of the write gate, applying the DFH control based on a size of a protrusion on the HAMR head from the assertion of the write gate.

31. The apparatus as claimed in claim 27 wherein the flying height compensation mechanism comprises, prior to the next assertion of the write gate, applying the DFH control based on a duration of the assertion of the write gate.

32. The apparatus as claimed in claim 27 wherein the flying height compensation mechanism comprises maintaining a history register of a count of the assertions of the write gate to adjust the DFH control.

33. The apparatus as claimed in claim 27 wherein the control circuitry is further configured to store values of the DFH control, for the write command, in a command execution memory.

34. The apparatus as claimed in claim 27 wherein the control circuitry is further configured to detect a skip mask or a media error to adjust the DFH control.

35. The apparatus as claimed in claim 27 wherein the control circuitry is further configured to monitor a closed loop circuit to measure the flying height while writing.

36. The apparatus as claimed in claim 27 wherein the control circuitry is further configured to establish a complex trigger to transfer the DFH control to a preamplifier.

37. The apparatus as claimed in claim 27 wherein the control circuitry is further configured to reorder execution of the write command including the DFH control selected for the write command.

38. The apparatus as claimed in claim 27 wherein the flying height compensation mechanism comprises a controller coupled to a preamplifier, a head-media space (HMS) detector and a DFH control in the HAMR head managed by the controller.

39. The apparatus as claimed in claim 27 further comprising a DFH timer configured to

monitor the update of a preamplifier serial port, to detect a set-up exception and a write fault error.

40. The apparatus as claimed in claim 27 wherein the apparatus is a controller for a data storage device.

41. An apparatus comprising:

a media;

a heat assisted magnetic recording (HAMR) head over the media; and

control circuitry, coupled to the HAMR head, the control circuitry being configured to;

receive a write command to write the media;

apply a dynamic flying height (DFH) control before asserting a write gate of the HAMR head;

assert the write gate to the HAMR head;

enable a flying height compensation mechanism to maintain a constant value of a flying height of the HAMR head over the media during a next assertion of the write gate; and

a DFH timer configured to monitor the update of a preamplifier serial port, to detect a set-up exception and a write fault error.