Near-field transducer efficiency monitoring system

Patent metadata

Field	Value
Publication number	US-9396750-B2
Application number	US-201514852755-A
Country	US
Kind code	B2
Filing date	Sep 14, 2015
Priority date	Feb 20, 2014
Publication date	Jul 19, 2016
Grant date	Jul 19, 2016

Abstract

A system may have a data storage medium that contains at least one data bit that is accessed by a transducing head that has a near-field transducer. A controller can be connected to the transducing head and store a plurality of near-field transducer operating currents in a memory. The controller may identify a change in efficiency of the near-field transducer from the plurality of near-field transducer operating currents.

First claim

What is claimed is:

1. A method comprising:
connecting a controller to a transducing head having a laser and a near-field transducer;
storing a plurality of laser operating currents with the controller;
decreasing an initial laser operating current to a first adjusted laser operating current in response to a measured bit error rate being lower than a maximum bit error rate;
selecting a second adjusted laser operating current from the plurality of laser operating currents in response to a detected device operating temperature, the second adjusted laser operating current being lower than the first adjusted laser operating current; and
accessing a data bit stored on a data storage medium with the second adjusted laser operating current.

2. The method of claim 1 , wherein the controller stores a drive temperature in a local memory for each of the plurality of laser operating currents.

3. The method of claim 1 , wherein the data storage medium comprises a reference data track with at least one reference data bit, the controller identifies the measured maximum bit error rate as a comparison between a first bit error rate of the reference data track and a second bit error rate of a user data track.

4. The method of claim 1 , wherein the controller selects the second adjusted laser operating current in to reduce the detected device operating temperature.

5. The method of claim 1 , wherein the second adjusted laser operating current is sufficient to raise the data storage medium above a Curie temperature for at least one constituent layer.

6. The method of claim 1 , wherein the controller forms an operating current map that correlates the plurality of laser operating currents with data storage device temperatures.

7. The method of claim 1 , wherein the controller suspends operation of the laser and near-field transducer in response to passing over a servo section of the data storage medium.

8. The method of claim 1 , wherein the controller directs scheduled tests of different laser operating currents prior to user data being stored on the data storage medium and after user data is stored on the data storage medium.

9. The method of claim 1 , wherein the controller selects the second adjusted laser operating current in response to a change in a real-time bit error rate.

10. An apparatus comprising a controller connected to a transducing head having a laser and a near-field transducer, the controller configured to store a plurality of laser operating currents and access a data bit stored on a data storage medium subsequent to an initial laser operating current decreasing to a first adjusted laser operating current then to a second adjusted laser operating current, the first and second laser operating currents each being selected from the plurality of laser operating currents, the first adjusted laser operating current corresponding with a measured bit error rate being lower than a maximum bit error rate, the second adjusted laser operating current selected in response to a detected device operating temperature.

11. The apparatus of claim 10 , wherein the laser is positioned to interact with the near-field transducer.

12. The apparatus of claim 10 , wherein the data storage medium comprises a plurality of layers to magnetically store a plurality of data bits.

13. The apparatus of claim 10 , wherein the transducing head, data storage medium, and controller comprise a heat assisted magnetic recording system.

14. The apparatus of claim 10 , wherein a laser preamp is connected to the controller and provides the plurality of laser operating currents.

15. A method comprising:
connecting a controller to a transducing head having a laser and a near-field transducer;
storing a plurality of laser operating currents with the controller;
comparing an initial laser operating current to a first adjusted laser operating current based on a measured bit error rate;
decreasing the initial laser operating current to the first adjusted laser operating current in response to the measured bit error rate being lower than a maximum bit error rate;
selecting a second laser operating current in response to a detected device operating temperature, the second adjusted laser operating current being lower than the first laser operating current; and
accessing a data bit stored on a data storage medium with the second adjusted laser operating current.

16. The method of claim 15 , wherein the plurality of laser operating currents comprises a range of different laser current values.

17. The method of claim 16 , wherein a bit error rate is measured and stored by the controller for each different laser current value.

18. The method of claim 15 , wherein at least one laser operating current is applied with a write enable preamp disabled.

19. The method of claim 15 , wherein a register control bit is set by the controller to enable detection of the first and second detected bit error rates without writing data to the data bit.

20. The method of claim 15 , wherein the controller identifies a minimum laser operating current that alters the data bit.

Assignees

• Seagate Technology Llc

Inventors

• Chu Alfredo
• Haapala Kenneth Arthur
• Burnett Paul William
• Chow Siew Kin

Classifications

• G11B2005/0021

  Thermally assisted recording using an auxiliary energy source for heating the recording layer locally to assist the magnetization reversal · CPC title

• G11B5/4866

  the arm comprising an optical waveguide, e.g. for thermally-assisted recording · CPC title

• G11B5/09

  Digital recording · CPC title

• G11B5/314

  where the layers are extra layers normally not provided in the transducing structure, e.g. optical layers (G11B5/3196 takes precedence) · CPC title

• G11B13/08 Primary

  using near-field interactions or transducing means and at least one other method or means for recording or reproducing · CPC title