HAMR thermal sensor with fast response time

Patent metadata

Field	Value
Publication number	US-10175122-B2
Application number	US-201615160325-A
Country	US
Kind code	B2
Filing date	May 20, 2016
Priority date	May 20, 2016
Publication date	Jan 8, 2019
Grant date	Jan 8, 2019

Abstract

Embodiments disclosed herein generally relate to a method for monitoring optical power in a HAMR device. In one embodiment, the method includes enhancing a thermal sensor bandwidth through advanced electrical detection techniques. The advanced electrical detection techniques include obtaining calibration waveform data for a thermal sensor by calibrating the thermal sensor, obtaining real-time waveform data for the thermal sensor that may deviate from the calibration waveform data, updating the calibration waveform data to include the real-time waveform data, repeating obtaining real-time waveform data and updating the calibration waveform data during writing operations. By updating the calibration waveform data, the bandwidth of the thermal sensor is determined by a fixed sampling time interval, and the thermal sensor rise time to steady state would not be a limitation to its response time.

First claim

What is claimed is:

1. A method, comprising:
obtaining calibration waveform data for a resistance of a thermal sensor;
measuring real-time waveform data for the resistance of the thermal sensor by sampling the resistance of the thermal sensor at a predetermined time interval, wherein the predetermined time interval corresponds to a bandwidth greater than a bandwidth of the thermal sensor;
determining deviated real-time waveform data;
updating the calibration waveform data to include the deviated real-time waveform data; and
repeating the measuring real-time waveform data, determining deviated real-time waveform data and updating the calibration waveform data.

2. The method of claim 1 , wherein the deviated real-time waveform data is greater than a predetermined threshold value.

3. The method of claim 2 , wherein the predetermined threshold value is at most one percent deviation from a resistance in the calibration waveform data.

4. The method of claim 1 , wherein the predetermined time interval ranges from about 5 nano seconds to about 20 nano seconds.

5. The method of claim 1 , wherein the deviated real-time waveform data is caused by a power fluctuation in a laser diode.

6. A method, comprising:
heating a thermal sensor to a predetermined temperature greater than an operating temperature of the thermal sensor;
maintaining the temperature of the thermal sensor at the predetermined temperature while the thermal sensor is operating at a steady state;
measuring and tracking a resistance value of the thermal sensor; and
maintaining the resistance value of the thermal sensor at a substantially constant value.

7. The method of claim 6 , wherein the predetermined temperature ranges from about 30 degrees Celsius to about 40 degrees Celsius.

8. The method of claim 6 , wherein the heating of the thermal sensor is performed by resistive heating.

9. The method of claim 6 , further comprising measuring and tracking a resistance of a reference sensor.

10. The method of claim 6 , wherein the maintaining the resistance value of the thermal sensor at the substantially constant value comprises increasing or decreasing a current flowing through the thermal sensor.

11. The method of claim 10 , wherein the increasing or decreasing the current flowing through the thermal sensor is performed by a preamplifier.

12. A method, comprising:
heating a thermal sensor to a predetermined temperature greater than an operating temperature of the thermal sensor;
obtaining calibration waveform data for a resistance of the thermal sensor;
obtaining real-time waveform data for the resistance of the thermal sensor;
updating the calibration waveform data to include the real-time waveform data;
repeating the obtaining real-time waveform data and updating the calibration waveform data;
maintaining the temperature of the thermal sensor at the predetermined temperature while the thermal sensor is operating at a steady state;
measuring and tracking a resistance value of the thermal sensor; and
maintaining the resistance value of the thermal sensor at a substantially constant value.

13. The method of claim 12 , wherein a deviation of the real-time waveform data from the calibration waveform data is greater than a predetermined threshold value.

14. The method of claim 13 , wherein the predetermined threshold value is at most one percent deviation from a resistance shown in the calibration waveform data.

15. The method of claim 12 , wherein the real-time waveform data is obtained by sampling the resistance of the thermal sensor at a predetermined time interval.

16. The method of claim 15 , wherein the predetermined time interval ranges from about 5 nano seconds to about 20 nano seconds.

17. The method of claim 12 , wherein the predetermined temperature ranges from about 30 degrees Celsius to about 40 degrees Celsius.

18. The method of claim 12 , wherein the heating of the thermal sensor is performed by resistive heating.

19. The method of claim 12 , wherein the maintaining the resistance value of the thermal sensor at the substantially constant value comprises increasing or decreasing a current flowing through the thermal sensor.

Assignees

• HGST Netherlands BV
• Western Digital Tech Inc

Inventors

• Contreras John T
• Huang Lidu
• Ren Shen
• Schreck Erhard
• Zakai Rehan A

Classifications

• G01K7/16

  using resistive elements · CPC title

• G01K15/005 Primary

  Calibration · CPC title

• G11B5/5534

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

• G11B2005/0021

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