TD detection with enhanced HDIs signal

Patent metadata

Field	Value
Publication number	US-10839843-B1
Application number	US-201916556691-A
Country	US
Kind code	B1
Filing date	Aug 30, 2019
Priority date	Aug 30, 2019
Publication date	Nov 17, 2020
Grant date	Nov 17, 2020

Abstract

A method of operating an HDD having a slider-mounted read/write head that is configured for dynamic fly-height operation (DFH) and includes at least one head-disk interference sensor (HDIs). By operating the DFH to lower the head and subjecting the HDIs signal to a power-law enhancement, a consistent and accurate determination of the touchdown power (TDP) can be obtained. Combining absolute TDP determination with a method for measuring relative changes of FH, an absolute determination of FH can be determined.

First claim

What is claimed is:

1. A method for operating a dynamic flying height (DFH)-configured read/write head to determine a touchdown power (TDP, or TD power), comprising:
providing a slider-mounted DFH-configured, read/write head operationally installed in a system wherein said read/write head is configured to controllably approach the surface of a rotating recording medium; wherein
said slider-mounted DFH-configured read/write head is mounted on a slider aerodynamically configured to support said DFH-configured read/write head at a stable flying height (FH) above a rotating magnetic recording medium; wherein
said slider-mounted read/write head includes at least one head/disk interference sensor (HDIs) and associated electronic equipment for receiving and processing signals generated by said HDIs; wherein
said slider-mounted read/write head further includes DFH apparatus to raise and lower said slider-mounted read/write head relative to a surface of said rotating recording medium;
generating an HDIs signal, x(t), as power is applied to said DFH apparatus and said slider-mounted read/write head approaches said surface of said rotating recording medium; then
enhancing said HDIs signal, x(t), by applying a power-law signal processing formula to x(t) to obtain y(t): y(t)=(abs(x(t))){circumflex over ( )}np, np=2, 3, . . . ,

while said approach occurs; and
determining a TDP using said enhanced signal y(t).

2. The method of claim 1 wherein said TDP provides an absolute reference point whereby a method of determining relative changes in slider height can be combined with said absolute reference point to create a method to determine a flying height (FH) of said slider-mounted read/write head.

3. The method of claim 1 wherein in said signal processing formula:
y ( t )=(abs( x ( t ))){circumflex over ( )} np, np= 2,3, . . . ,

np can be chosen to produce an optimal comparison with an independent measuring device.

4. The method of claim 3 wherein np is an even integer and the absolute value of x(t) is its positive value.

5. The method of claim 3 wherein said independent measuring device is a laser doppler vibrometer (LDV).

6. The method of claim 1 wherein said signal processing further includes a step of filtering, either before or after said enhancement of the signal.

7. The method of claim 1 wherein said signal processing further includes a step of signal amplification either before or after said enhancement of the signal.

8. The method of claim 1 applied to the manufacture of active HDD components, said components including a slider and/or a head gimbal assembly (HGA) and said application occurring during electric or dynamic electric test (ET, or DET) during manufacturing of said HDD components (slider and/or HGA).

9. A dynamic flying height (DFH)-configured read/write head having an absolutely determined touchdown point (TDP), comprising:
a slider-mounted DFH-configured, read/write head operationally installed in a system wherein said read/write head is configured to controllably approach the surface of a rotating recording medium; wherein
said slider-mounted DFH-configured read/write head is mounted on a slider aerodynamically configured to support said DFH-configured read/write head at a stable flying height (FH) above a rotating magnetic recording medium; wherein
said slider-mounted DFH-configured read/write head comprises at least one head/disk interference sensor (HDIs) and associated electronic equipment for receiving and processing signals generated by said HDIs; wherein
said slider-mounted read/write head further comprises a DFH apparatus configured to raise and lower said slider-mounted read/write head relative to a surface of said rotating recording medium; wherein
said HDIs is configured to generate a signal, x(t), as power is applied to said DFH apparatus and said slider-mounted read/write head approaches said surface of said rotating recording medium; wherein
said HDIs signal is configured to be processed and enhanced signal y(t) while said approach occurs and a TDP is determined using y(t); and
wherein said read/write head is configured to apply the following power-law transformation to said HDIs signal x(t) to obtain y(t): y(t)=(abs(x(t))){circumflex over ( )}np, np=2, 3, . . . , .

10. The DFH-configured read/write head claim 9 wherein said TDP provides an absolute reference point wherein, by combining said absolute TDP with a method of determining relative changes in slider height a flying height (FH) of said slider-mounted read/write head is obtained.

11. The DFH-configured read/write head of claim 9 wherein in the use of the power-law signal processing formula:
y ( t )=(abs( x ( t ))){circumflex over ( )} np, np= 2,3, . . . ,

np can be chosen to produce an optimal comparison with an independent measuring device.

12. The DFH-configured read/write head of claim 11 wherein said independent measuring device is a laser doppler vibrometer (LDV).

13. The DFH-configured read/write head of claim 9 wherein said signal processing further includes a step of filtering, either before or after said enhancement of the signal.

14. The DFH-configured read/write head of claim 9 wherein said signal processing further includes a step of signal amplification either before or after said enhancement of the signal.

15. A head-gimbal assembly, comprising:
the DFH-configured read/write head of claim 9 ; a suspension that elastically supports said DFH-configured read/write head;
a flexure affixed to said suspension and a load beam having one end attached to said flexure and another end attached to a base plate.

16. A hard disk drive (HDD), comprising:
said head gimbal assembly of claim 15 ;
a magnetic recording medium positioned opposite to said DFH-configured read/write head;
a spindle motor that rotates and drives said magnetic recording medium;
a device that positions said DFH-configured read/write head relative to said magnetic recording medium.

Assignees

• Sae Magnetics Hk Ltd
• Headway Tech Inc

Inventors

• Zeng Qinghua
• Ka Soramany
• Cha Ellis

Classifications

• G11B2005/0018

  by current biasing control or regulation · CPC title

• G11B5/6076 Primary

  Detecting head-disk contact · CPC title

• G11B5/6052

  using optical means · CPC title

• G11B5/5534

  Initialisation, calibration, e.g. cylinder "set-up" · CPC title

• G11B5/4555 Primary

  by using a spin-stand, i.e. a spinning disc or simulator · CPC title