Per wedge preheat DFH to improve data storage device performance

• US 9,230,585 B1
• Filed: 01/31/2014
• Issued: 01/05/2016
• Est. Priority Date: 01/31/2014
• 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: Ruan, Huanxiang
• Primary Examiner(s): Sniezek, Andrew L
• Application Number:
  US14/169,514
• Time in Patent Office: 704 Days
• Field of Search: None
• US Class Current: 1/1
• CPC Class Codes: G11B 5/5521 across disk tracks spiral track following G11B5/596
• CPC Class Codes: G11B 5/5547 "Seek" control and circuits therefor G11B5/5556 takes precedence
• CPC Class Codes: G11B 5/596 for track following on disks G11B5/5526, G11B5/5552, G11B5/5565, G11B5/5582 take precedence
• 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

A disk drive is disclosed including a disk having a plurality of tracks, wherein each track comprises a plurality of data sectors and a plurality of servo sectors. The disk drive further comprises a spindle motor for rotating the disk, and a head actuated radially over the disk, wherein the head comprises a dynamic fly height (DFH) heater. Control circuitry within the disk drive is operable to position the head over one of the tracks; determine a number of servo sectors to pass under the head before a target location over the track is reached, apply an initial amount of power to the DFH heater that is dependent at least in part on the determined number of servo sectors, and decrease the initially-applied amount of power applied to the DFH heater until a predetermined target power is reached.

Claims

1. A data storage device comprising:

a disk comprising a plurality of tracks, each track comprising a plurality of data sectors and a plurality of servo sectors;

a spindle motor for rotating the disk;

a had actuated radially over the disk, the head comprising a dynamic fly height (DFH heater; and

control circuitry configured to;

position the head over one of the tracks;

determine a number of servo sectors to pass under the head before a target location over the track is reached;

apply an initial amount of power to the DFH heater that is dependent at least m part on the determined number of servo sectors; and

decrease the initially-applied amount of power before the target location comes under the head until a predetermined target power is reached.

2. The data storage device of claim 1, wherein the initially-applied amount of power is greater than a constant amount of power necessary for the bead to reach the target location at a predetermined height without decreasing the applied power.

3. The data storage device of claim 2, wherein the initially-applied amount of power is between about 10% and about 100% greater than the constant amount of power.

4. The data storage device of claim 1, wherein the control circuitry is further configured to decrease the power applied to the DFH heater after each of the determined number of servo sectors passes under the head.

5. The data storage device of claim 1, wherein the power applied to the DFH heater is maintained substantially constant during at least a portion of a time between next adjacent servo sectors pass under the head.

6. A method of operating a data storage device, the disk drive comprising a disk comprising a plurality of tracks, each track comprising a plurality of data sectors and a plurality of servo sectors, a spindle motor for rotating the disk, and a head actuated radially over the disk, the head comprising a dynamic fly height (DFH) heater, the method comprising:

positioning the head over one of the tracks;

determining a number of servo sectors to pass under the head before a target location over the track is reached;

applying an initial amount of power to the DFH heater that is based at least in part on the determined number of servo sectors; and

decreasing the initially-applied amount of power applied to the DFH heater before the target location comes under the head until a predetermined target power is reached.

7. The method of claim 6, wherein the initially-applied amount of power is greater than a constant amount of power necessary for the head to reach the target location at a predetermined height without decreasing the applied power.

8. The method of claim 7, wherein the initially-applied amount of power is between about 10% and about 100% greater than the constant amount of power.

9. The method of claim 6, wherein decreasing decreases the power applied to the DFH heater monotonically.

10. The method of claim 6, further comprising maintaining the power applied to the DFH heater substantially constant during, at least a portion of a time between next adjacent servo sectors pass under the head.

11. A data storage device comprising:

a disk comprising a plurality of tracks, each track comprising a plurality of data sectors and a plurality of servo sectors;

a spindle motor for rotating the disk;

a head actuated radially over the disk the head comprising a dynamic fly height (DFH) heater; and

control circuitry configured to;

position the head over a given one of the tracks;

determine a period of time before the head reaches a target location over the given track;

apply an initial amount of power, while the head is over the given track, to the DFH heater that is dependent at least in part on the determined period of time, the initially-applied amount of power being an amount of power of a plurality of amounts of power that are each dependent upon an amount of time before the head reaches a tartlet location on a track being followed; and

decrease, while the head is over the given track, the initially-applied amount of power applied to the DFH heater during the period of time until a predetermined target power is reached, the predetermined target power being associated with a height, of the head over the given track, that is suitable for read and/or write operations.

12. The disk drive of claim 11, wherein the control circuitry is further configured to determine the period of time by at least measuring a wedge-to-wedge time between two of the servo sectors.

13. A method, comprising:

providing a disk drive, the disk drive comprising a disk comprising a plurality of tracks, each track comprising a plurality of data sectors and a plurality of servo sectors, a spindle motor for rotating the disk, and a head actuated radially over the disk, the head comprising a dynamic fly height (DFH) heater;

positioning the head over a then one of the tracks;

determining a period of time before the head reaches a target location on the given track;

applying, while the bead is over the given track an initial amount of to the DFH heater that is dependent at least in part on the determined period of time, the initially-applied amount of power being an amount of power of a plurality of amounts of power that are each dependent upon an amount of time before the head reaches a target location on a track being followed; and

decreasing, while the head is over the given track, the initially-applied amount of power applied to the DFH heater doting the period of time until a predetermined target power reached, the predetermined target power being associated with a height of the head over the given track that is suitable for read and/or write operations.

14. The method of claim 13, wherein determining the period of time comprises at least measuring a wedge-to-wedge time between two of the servo sectors.

15. A data storage device comprising:

a disk comprising a plurality of tracks, each track comprising a plurality of data sectors and a plurality of servo sectors;

a spindle motor for rotating the disk;

a head actuated radially over the disk, the head comprising a dynamic fly height (DFH) heater; and

control circuitry configured to;

position the head over one of the tracks;

determine a number of servo sectors to pass under the head before a target location over the track is reached;

apply an initial amount of power to the DFH heater that is dependent at least in part on the determined number of servo sectors; and

before the target location comes under the head, decrease the initially-applied amount of power after each or the determined number of servo sectors, until a predetermined target power is reached.

16. A method of operating a data storage device, the data storage device comprising a disk comprising a plurality of tracks, each track comprising a plurality of data sectors and a plurality of servo sectors, a spindle motor for rotating the disk, and a head actuated radially over the disk, the head comprising a dynamic fly height (DFH) heater, the method comprising:

positioning the head over one of the tracks;

determining a number of servo sectors to pass under the head before a target location over the track is reached;

applying an initial amount of power to the DFH heater that is based at least in part on the determined number of servo sectors; and

before the target location comes under the head and until a predetermined target power is reached, decreasing the initially-applied amount of power applied to the DFH heater after each or the determined number of servo sectors passes under the head.