Magnetic recording device including a thermal proximity sensor
View Patent ↗A system includes a magnetic device for writing to and reading from a magnetic medium and a sensor disposed adjacent to the magnetic device and proximate to the magnetic medium. The sensor generates signals related to thermal variations in the sensor caused by changes in a distance between the magnetic device and the magnetic medium.
1. A system comprising:
a magnetic device comprising a main pole for writing to a magnetic medium and a read element for reading from the magnetic medium;
a thermal sensor spaced from the main pole and separate from the read sensor, disposed adjacent to the magnetic device and at or near a medium confronting surface proximate the magnetic medium, wherein the sensor generates signals related to thermal variations caused by changes in a distance between the magnetic device and the magnetic medium, wherein a resistance of the sensor increases in response to the thermal variations, and wherein the increase in resistance is measured by passing a sense current through the sensor;
a heating element for heating the sensor to vary a sensitivity of the sensor to the thermal variations; wherein the sense current passes through the sensor and the heating element in series or in parallel;
an actuator separate from the sensor for varying the distance between the magnetic device and the magnetic medium; and
a controller that controls the actuator to control the distance between the magnetic device and the magnetic medium in response to the sensor signals.
2. The system of claim 1 , wherein the sense current passes though the sensor and heating element in series.
3. The system of claim 1 , wherein the sense current passes through the sensor and heating element in parallel.
4. The system of claim 1 , wherein the sensor further generates signals related to a clearance of the magnetic device from the magnetic medium.
5. The system of claim 1 , wherein the sensor is spaced at least 1.0 μm from a tip of the main pole.
6. The system of claim 1 , wherein the sensor is comprised of a material having a high thermal coefficient of resistivity and low magnetoresistance.
7. The system of claim 1 , wherein the sensor is comprised of an inert material.
8. The system of claim 1 , wherein the sensor is embedded in a metallic material.
9. A magnetic recording system comprising:
a magnetic recording device comprising a main pole for writing data to a magnetic medium and a read element for reading data from the magnetic medium, and having a medium confronting surface facing the magnetic medium;
a thermal sensor spaced from the main pole and separate from the read element, disposed adjacent to the magnetic recording device, at or near the medium confronting surface and proximate to the magnetic medium, wherein the sensor generates signals related to thermal variations caused by changes in a distance between the magnetic recording device and the magnetic medium, wherein a resistance of the sensor increases in response to the thermal variations, and wherein the increase in resistance is measured by passing a sense current through the sensor;
a heating element for heating the sensor to vary a sensitivity of the sensor to the thermal variations, wherein the sense current passes through the sensor and heating element in series or in parallel;
an actuator separate from the sensor for varying the distance between the magnetic device and the magnetic medium; and
a controller that controls the actuator to control the distance between the magnetic recording device and the magnetic medium in response to the sensor signals.
10. The magnetic recording system of claim 9 , wherein the controller is operable to map a topography of the magnetic medium based on the sensor signals.
11. The magnetic recording system of claim 9 , wherein the sensor further generates signals related to a thermal spike caused by contact between the magnetic recording device and asperities on the magnetic medium.
12. The magnetic recording system of claim 9 , wherein the distance between the magnetic recording device and the magnetic medium is controlled by heating at least a portion of the magnetic recording device.
13. The magnetic recording system of claim 9 , wherein the sensor further generates signals related to a clearance of the magnetic device from the magnetic medium.
14. The magnetic recording system of claim 9 , wherein the sense current passes through the sensor and heating element in series.
15. The magnetic recording system of claim 9 , wherein the sense current passes through the sensor and heating element in parallel.
16. The magnetic recording system of claim 9 , wherein the sensor is spaced at least 1.0 μm from a tip of the main pole.
17. The magnetic recording system of claim 9 , wherein the sensor is comprised of a material having a high thermal coefficient of resistivity and low magnetoresistance.
18. The magnetic recording system of claim 9 , wherein the sensor is comprised of a noble metal.
19. A system comprising:
a magnetic device comprising a main pole for writing to a magnetic medium and a read element for reading from the magnetic medium;
a thermal sensor spaced from the main pole and separate from the read element, disposed adjacent to the magnetic device and at or near a medium confronting surface proximate the magnetic medium, wherein the sensor generates signals related to thermal variations caused by changes in a distance between the magnetic device and the magnetic medium, wherein a resistance of the sensor increases in response to the thermal variations, wherein the increase in resistance is measured by passing a sense current through the sensor, and wherein the sensor is heated by increasing the amplitude of the sense current to increase a sensitivity of the sensor to thermal variations;
an actuator separate from the sensor for varying the distance between the magnetic device and the magnetic medium; and
a controller that controls the actuator to control the distance between the magnetic device and the magnetic medium in response to the sensor signals.
20. A magnetic recording system comprising:
a magnetic recording device comprising a main pole for writing data to a magnetic medium and a read element for reading data from the magnetic medium, and having a medium confronting surface facing the magnetic medium;
a thermal sensor spaced from the main pole and separate from the read element, disposed adjacent to the magnetic recording device, at or near the medium confronting surface and proximate to the magnetic medium, wherein the sensor generates signals related to thermal variations caused by changes in a distance between the magnetic recording device and the magnetic medium, wherein a resistance of the sensor increases in response to the thermal variations, wherein the increase in resistance is measured by passing a sense current through the sensor, and wherein the sensor is heated by increasing the amplitude of the sense current to increase a sensitivity of the sensor to thermal frictional heating;
an actuator separate from the sensor for varying the distance between the magnetic device and the magnetic medium; and
a controller that controls the actuator to control the distance between the magnetic recording device and the magnetic medium in response to the sensor signals.