Measurement of a reversed side shield magnetization condition

Patent metadata

Field	Value
Publication number	US-9928858-B1
Application number	US-201715702571-A
Country	US
Kind code	B1
Filing date	Sep 12, 2017
Priority date	Sep 12, 2017
Publication date	Mar 27, 2018
Grant date	Mar 27, 2018

Abstract

A method that includes supplying a predetermined signal to a write head having side shields. The method also includes performing, by the write head, a recording operation on a surface of a data storage medium, when the predetermined signal is supplied to the write head, to provide a recorded magnetization pattern. The method further includes carrying out measurements on a portion of the recorded magnetization pattern influenced by a magnetization of the side shields. The measurements are employed to determine whether a reversed side shield magnetization condition is present in the write head.

First claim

What is claimed is:

1. A method comprising:
supplying, by a controller, a predetermined signal to a write head having side shields;
when the predetermined signal is supplied to the write head, performing, by the write head, a recording operation on a surface of a data storage medium to provide a recorded magnetization pattern;
carrying out measurements on a portion of the recorded magnetization pattern influenced by a magnetization of the side shields; and
determining whether a reversed side shield magnetization condition is present in the write head from the measurements.

2. The method of claim 1 and wherein the predetermined signal is a single-frequency alternating current signal.

3. The method of claim 1 and further comprising performing a first direct current (DC) erase operation on the surface of the data storage medium prior to performing the recording operation on the surface of the data storage medium.

4. The method of claim 3 and further comprising performing a second DC erase operation to erase portions of the recorded magnetization pattern not substantially influenced by the magnetization of the side shields before carrying out the measurements on the portion of the recorded magnetization pattern influenced by the magnetization of the side shields.

5. The method of claim 4 and wherein the recording operation on the surface of the data storage medium is carried out on a single track of the data storage medium.

6. The method of claim 5 and wherein the DC erase operation is carried out on the single track, and wherein the DC erase operation covers a width that is about 1.4 to about 1.6 times a width of the single track.

7. The method of claim 5 and wherein the measurements on the portion of the recorded magnetization pattern influenced by the magnetization of the side shields is carried out at a track distance of about 2 tracks away from the single track on which the magnetization pattern is recorded.

8. The method of claim 7 and wherein the measurements comprise a first measurement on a first side of the single track on which the magnetization pattern is recorded and a second measurement on a second side of the single track on which the magnetization pattern is recorded.

9. The method of claim 8 and further comprising computing a ratio of the first measurement to the second measurement.

10. The method of claim 9 and further comprising determining that the reversed side shield magnetization condition is present in the write head if the computed ratio is above a predetermined value.

11. A data storage device comprising:
a data storage medium;
a write head having side shields;
a controller operably coupled to the data storage medium and the write head, the controller is configured to:
direct the write head to record a test magnetization pattern on the data storage medium;
carry out measurements on a portion of the recorded test magnetization pattern influenced by a magnetization of the side shields; and
determine whether a reversed side shield magnetization condition is present in the write head from the measurements.

12. The data storage device of claim 11 and wherein the controller is further configured to supply the write head with a predetermined signal when the write head records the test magnetization pattern on the data storage medium.

13. The data storage device of claim 12 and wherein the predetermined signal is a single-frequency alternating current signal.

14. The data storage device of claim 12 and wherein the data storage device comprises a hard disc drive.

15. The data storage device of claim 12 and wherein the data storage device comprises a test device configured to test a plurality of write heads.

16. A method comprising:
writing, by a write head having side shields, a test magnetization pattern on a data storage medium;
carrying out measurements on a portion of the test magnetization pattern influenced by a magnetization of the side shields; and
determining whether a reversed side shield magnetization condition is present in the write head from the measurements.

17. The method of claim 16 and further comprising supplying the write head with a predetermined signal when the write head records the test magnetization pattern on the data storage medium.

18. The method of claim 16 and wherein the predetermined signal is a single-frequency alternating current signal.

19. The method of claim 16 and further comprising performing a first direct current (DC) erase operation on the data storage medium prior to writing the test magnetization pattern on the data storage medium.

20. The method of claim 19 and further comprising performing a second DC erase operation to erase on portions of the test magnetization pattern not substantially influenced by the magnetization of the side shields before carrying out the measurements on the portion of the test magnetization pattern influenced by the magnetization of the side shields.

Assignees

• Seagate Technology Llc

Inventors

• Shen Zhe
• Lin Zuxuan
• Lu Lei
• Zhong Jian

Classifications

• G11B5/1278

  specially adapted for magnetisations perpendicular to the surface of the record carrier · CPC title

• G11B5/3166

  Testing or indicating in relation thereto, e.g. before the fabrication is completed · CPC title

• G11B5/315

  Shield layers on both sides of the main pole, e.g. in perpendicular magnetic heads · CPC title

• G11B5/3196

  of thin magnetic films, e.g. functional testing of the transducing properties (G11B5/455 takes precedence) · CPC title

• G11B5/3116 Primary

  Shaping of layers, poles or gaps for improving the form of the electrical signal transduced, e.g. for shielding, contour effect, equalizing, side flux fringing, cross talk reduction between heads or between heads and information tracks (G11B5/3113, G11B5/245 take precedence) · CPC title