Resistance temperature sensors for head-media and asperity detection
View Patent ↗A temperature sensor of a head transducer measures temperature near or at the close point. The measured temperature varies in response to changes in spacing between the head transducer and a magnetic recording medium. A detector is coupled to the temperature sensor and is configured to detect a change in a DC component of the measured temperature indicative of onset of contact between the head transducer and the medium. Another head transducer configuration includes a sensor having a sensing element with a high temperature coefficient of resistance to interact with asperities of the medium. Electrically conductive leads are connected to the sensing element and have a low temperature coefficient of resistance relative to that of the sensing element, such thermally induced resistance changes in the leads have a negligible effect on a response of the sensing element to contact with the asperities.
1. An apparatus, comprising:
a head transducer; and
a sensor situated on the head transducer to interact with asperities of a magnetic recording medium, the sensor comprising:
a sensing element having a high temperature coefficient of resistance; and
electrically conductive leads connected to the sensing element, the leads having a low temperature coefficient of resistance relative to that of the sensing element such that thermally induced resistance changes in the leads have a negligible effect on a response of the sensing element to asperities.
2. The apparatus of claim 1 , wherein the response of the sensing element to asperities is not confounded by temperature induced resistance changes in the leads.
3. The apparatus of claim 1 , wherein the leads are formed of a material having a near-zero temperature coefficient of resistance.
4. The apparatus of claim 1 , wherein the leads comprise a NiCu alloy film.
5. The apparatus of claim 1 , wherein the leads comprise a NiCu50% alloy film having a thickness of about 100 nm.
6. The apparatus of claim 1 , wherein the sensing element is formed of a material comprising NiFe, Ni, Ru or Cr.
7. The apparatus of claim 1 , further comprising a detector coupled to the sensor and configured to detect asperities.
8. A method, comprising:
moving a magnetic recording medium relative to a head transducer:
sensing for asperities of the medium using a sensor comprising a sensing element having a high temperature coefficient of resistance coupled to electrically conductive leads having a low temperature coefficient of resistance relative to that of the sensing element such that thermally induced resistance changes in the leads have a negligible effect on a response of the sensing element to asperities.
9. The method of claim 8 , wherein leads are formed of a material having a near-zero temperature coefficient of resistance.
10. An apparatus, comprising:
a slider that supports a transducer configured to interact with a magnetic recording medium, the slider comprising an airbearing surface; and
a sensor situated on the slider and configured to sense asperities of the medium, the sensor comprising:
a sensing element disposed at or proximate the airbearing surface and having a high temperature coefficient of resistance; and
a lead arrangement electrically connected to the sensing element, the lead arrangement having a low temperature coefficient of resistance relative to that of the sensing element such that thermally induced resistance changes in the lead arrangement have a negligible effect on a response of the sensing element to asperities.
11. The apparatus of claim 10 , wherein the sensing element has a longitudinal axis aligned approximately parallel with the airbearing surface.
12. The apparatus of claim 10 , wherein:
the sensing element has a cross-track length (L), an into-slider body depth (D), and a down track width (W); and
the cross-track length (L) is greater than the into-slider body depth (D) by a factor of at least about 8.
13. The apparatus of claim 10 , wherein the sensing element has a generally gull wing shape.
14. The apparatus of claim 10 , wherein:
the lead arrangement comprises:
a first lead connected to a first distal portion of the sensing element; and
a second lead connected to a second distal portion of the sensing element; and
the first and second distal portions of the sensing element are disposed between the airbearing surface and at least a portion of the first and second leads.
15. The apparatus of claim 10 , wherein:
the lead arrangement comprises:
a first lead connected to a first distal portion of the sensing element; and
a second lead connected to a second distal portion of the sensing element;
the sensing element comprises a thinned section between the first and second distal portions; and
the thinned section of the sensing element is situated within a gap between the first and second leads.
16. The apparatus of claim 10 , wherein leads of the lead arrangement are formed of a material having a zero or near-zero temperature coefficient of resistance.
17. The apparatus of claim 10 , wherein leads of the lead arrangement comprise a NiCu alloy film.
18. The apparatus of claim 10 , wherein leads of the lead arrangement comprise a NiCu50% alloy film having a thickness of about 100 nm.
19. The apparatus of claim 10 , wherein the sensing element is formed of a material comprising NiFe, Ni, Ru or Cr.
20. The apparatus of claim 10 , further comprising a detector coupled to the sensor and configured to detect asperities.
21. The apparatus of claim 10 , wherein leads of the lead arrangement have a resistivity greater than a resistivity of the sensor.
22. The apparatus of claim 10 , wherein leads of the lead arrangement have a resistivity greater than a resistivity of the sensor.