IP Library › Granted Patent US 9,111,572
Granted Patent B2
US 9,111,572 · App. 14/287,412 · Granted Aug 18, 2015

Asperity and head-media contact detection using multi-stage temperature coefficient of resistance sensor

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Quick Facts
Patent No.
US 9,111,572
App. No.
14/287,412
Granted
Aug 18, 2015
Kind
B2
Abstract

A multi-stage sensor is situated on the head transducer and configured to interact with a magnetic recording medium. A first sensor stage of the multi-stage sensor has a temperature coefficient of resistance. A second sensor stage of the multi-stage sensor is coupled to the first sensor and has a temperature coefficient of resistance. The first sensor stage is configured to preferentially sense asperities of the media relative to the second sensor stage, and the second sensor stage configured to preferentially sense proximity to, and contact with, a surface of the media relative to the first sensor stage. The first and second sensor stages may be connected in series or in parallel.

Claims (40)

1. An apparatus, comprising:

a slider supporting a transducer configured to interact with a magnetic recording medium, the slider comprising an airbearing surface having an actuatable close point; and

a sensor at or near the close point, the sensor comprising:

a first resistive temperature sensor; and

a second resistive temperature sensor coupled to the first sensor;

the first sensor configured to preferentially sense asperities of the medium relative to the second sensor; and

the second sensor configured to preferentially sense contact with a surface of the medium relative to the first sensor.

2. The apparatus of claim 1 , wherein the second sensor is connected in series with the first sensor.

3. The apparatus of claim 1 , wherein the first sensor operates at a temperature higher than that of the second sensor.

4. The apparatus of claim 1 , wherein:

the first sensor is sensitive to changes in heat flow across a small sensing area relative to that of the second sensor; and

the second sensor is sensitive to changes in heat flow across a large sensing area relative to that of the first sensor.

5. The apparatus of claim 1 , wherein:

the first sensor has a length, a width, and a depth; and

the second sensor has a length, a width, and a depth, where the length and the width of the second sensor is greater than the length and the width of the first sensor.

6. The apparatus of claim 1 , wherein the first and second sensors are configured to operate alternately.

7. The apparatus of claim 1 , wherein the first and second sensors define a unitary structure, and at least a portion of the first sensor is situated between portions of the second sensor.

8. The apparatus of claim 1 , wherein;

the first and second sensors each comprise a leading edge and a trailing edge; and

the leading edge of the first sensor is recessed relative to the leading edge of the second sensor.

9. The apparatus of claim 1 , wherein the first sensor comprises a plurality of spaced-apart first sensor portions, and the second sensor comprises a plurality of spaced-apart second sensor portions.

10. The apparatus of claim 1 , wherein each of the first and second sensors is configured to operate independently.

11. The apparatus of claim 1 , wherein the second sensor is connected in parallel with the first sensor.

12. The apparatus of claim 11 , wherein a resistance of the second sensor is greater than that of the first sensor.

13. The apparatus of claim 11 , wherein the second sensor comprises at least two spaced-apart portions configured to concurrently measure contact with at least two spaced-apart locations of the surface of the medium.

14. An apparatus, comprising:

a slider supporting a transducer configured to interact with a magnetic recording medium, the slider comprising a thermal actuator and an airbearing surface having a thermally actuatable close point; and

a sensor at or near the close point, the sensor comprising:

a first resistive temperature sensor; and

a second resistive temperature sensor coupled to the first sensor;

the first sensor configured to preferentially sense asperities of the medium relative to the second sensor; and

the second sensor configured to preferentially sense contact with a surface of the medium relative to the first sensor.

15. The apparatus of claim 14 , wherein the thermal actuator comprises a heater.

16. The apparatus of claim 14 , wherein the thermal actuator comprises a writer.

17. The apparatus of claim 14 , wherein the second sensor is connected in series with the first sensor.

18. The apparatus of claim 14 , wherein the second sensor is connected in parallel with the first sensor.

19. The apparatus of claim 14 , wherein the first sensor operates at a temperature higher than that of the second sensor.

20. The apparatus of claim 14 , wherein:

the first sensor is sensitive to changes in heat flow across a small sensing area relative to that of the second sensor; and

the second sensor is sensitive to changes in heat flow across a large sensing area relative to that of the first sensor.