Resistive temperature sensors for improved asperity, head-media spacing, and/or head-media contact detection
View Patent ↗A sensor supported by a head transducer has a temperature coefficient of resistance (TCR) and a sensor resistance. The sensor operates at a temperature above ambient and is responsive to changes in sensor-medium spacing. Conductive contacts connected to the sensor have a contact resistance and a cross-sectional area adjacent to the sensor larger than that of the sensor, such that the contact resistance is small relative to the sensor resistance and negligibly contributes to a signal generated by the sensor. A multiplicity of head transducers each support a TCR sensor and a power source can supply bias power to each sensor of each head to maintain each sensor at a fixed temperature above an ambient temperature in the presence of heat transfer changes impacting the sensors. A TCR sensor of a head transducer can include a track-oriented TCR sensor wire for sensing one or both of asperities of the medium.
1. An apparatus, comprising:
a head transducer configured to write and read data respectively to and from a magnetic recording medium;
a sensor provided at the head transducer and having a temperature coefficient of resistance and a sensor resistance, the sensor configured to operate at a temperature above an ambient temperature and responsive to changes in spacing between the sensor and the medium; and
electrically conductive contacts connected to the sensor and having a contact resistance, the contacts having a cross-sectional area adjacent to the sensor larger than that of the sensor such that the contact resistance is small relative to the sensor resistance and negligibly contributes to a signal generated by the sensor.
2. The apparatus of claim 1 , wherein the contact resistance is negligible relative to the sensor resistance.
3. The apparatus of claim 1 , wherein:
the sensor has an effective size and a physical size; and
a contribution to the sensor signal by the effective size of the sensor is substantially the same as a contribution to the sensor signal by the physical size of the sensor.
4. The apparatus of claim 1 , wherein the sensor signal is not confounded by a component of the signal contributed by the contacts.
5. The apparatus of claim 1 , wherein:
a region of the contacts is exposed to thermal energy produced by one or both of the sensor and a heater of the head transducer; and
the contact resistance of the contact regions is small relative to the sensor resistance and negligibly contributes to the signal generated by the sensor.
6. The apparatus of claim 1 , wherein:
the sensor comprises a sensor element and opposing ends between the sensor element;
the opposing ends of the sensor have a cross-sectional area larger than that of the sensor element; and
the sensor contacts comprise the opposing ends of the sensor.
7. The apparatus of claim 1 , wherein the contacts have a cross-sectional area adjacent to the sensor which is larger than that of the sensor by a factor ranging between 1 and 1000.
8. The apparatus of claim 1 , wherein the contact resistance is smaller than the sensor resistance by a factor ranging between 1 and 1000.
9. The apparatus of claim 1 , wherein;
the each of the contacts and the sensor comprises a leading edge and a trailing edge; and
the leading edge of the sensor is recessed relative to the leading edge of the contacts.
10. The apparatus of claim 1 , wherein the sensor is configured to operate at a temperature of about 0° C. to 300° C.
11. The apparatus of claim 1 , wherein the sensor is situated at or near a close point of the head transducer.
12. The apparatus of claim 1 , wherein the sensor is dimensioned to sense for asperities of the medium.
13. A method, comprising:
with a magnetic recording medium moving relative to a head transducer configured to write and read data respectively to and from the magnetic recording medium:
sensing temperature at a close point of the head transducer using a sensor having a temperature coefficient of resistance connected to electrically conductive contacts having a contact resistance, the contacts having a cross-sectional area adjacent to the sensor larger than that of the sensor such that the contact resistance is small relative to a resistance of the sensor and negligibly contributes to a signal generated by the sensor;
outputting the sensor signal; and
detecting asperities of the medium using the sensor signal.
14. The method of claim 13 , wherein the sensor signal is not confounded by a component of the signal contributed by the contacts.
15. The method of claim 13 , wherein the contact resistance is negligible relative to the sensor resistance.
16. The method of claim 13 , wherein:
the sensor has an effective size and a physical size; and
a contribution to the sensor signal by the effective size of the sensor is substantially the same as a contribution to the sensor signal by the physical size of the sensor.
17. The method of claim 13 , wherein:
a region of the contacts is exposed to thermal energy produced by one or both of the sensor and a heater of the head transducer; and
the contact resistance of the contact regions is small relative to the sensor resistance and negligibly contributes to the signal generated by the sensor.
18. The method of claim 13 , wherein:
the sensor comprises a sensor element and opposing ends between the sensor element;
the opposing ends of the sensor have a cross-sectional area larger than that of the sensor element; and
the sensor contacts comprise the opposing ends of the sensor.
19. The method of claim 13 , wherein the sensor is situated at or near a close point of the head transducer.
20. The method of claim 13 , wherein;
the each of the contacts and the sensor comprises a leading edge and a trailing edge; and
the leading edge of the sensor is recessed relative to the leading edge of the contacts.