Electromagnetic void-sensing probes and position control systems
View Patent ↗In one aspect, an electromagnetic or capacitive sensing position system for determining the relative position of at least one void in a conductive material is provided. In one example, the system includes a sensor (or probe) having at least two probe elements (e.g., tips or plates). The position of the probe relative to the at least one void is determined in response to an electrical signal (e.g., a differential signal) measured across the two probe elements that varies in response to interaction of the probe elements with the at least one void. The system may be used, e.g., to servo a magnetic head assembly relative to a magnetic storage tape.
1. A system for sensing a position of a conductive material having at least one void formed therein, comprising:
a sensor having a two-dimensional array of probe elements, wherein the sensor generates a signal in response to an electrical measurement across at least two of the probe elements that varies in response to an interaction of the at least two probe elements with the at least one void.
2. The system of claim 1 , further including a transducer head having at least one magnetic read element.
3. The system of claim 2 , wherein the position sensor and the transducer head are positioned adjacent each other on one side of an expected position of the conductive material.
4. The system of claim 2 , wherein the position sensor and the transducer head are positioned opposing each other on opposite sides of an expected position of the conductive material.
5. The system of claim 2 , further including a controller configured to adjust the position of the transducer head relative to the conductive material in response to one or more signals from the position sensor.
6. The system of claim 2 , wherein the transducer head includes a read/write head having at least one active island.
7. The system of claim 1 , wherein the probe elements include tips.
8. The system of claim 7 , wherein the tips have a diameter of approximately 6 μm and are spaced at a pitch of approximately 12 μm.
9. The system of claim 1 , wherein the at probe elements include plates.
10. The system of claim 1 , wherein the signal is associated with a difference in current through at least a portion of the probe elements.
11. The system of claim 1 , wherein the signal is associated with a difference in potential of at least a portion of the probe elements.
12. The system of claim 1 , wherein the signal is associated with a change in capacitance of at least a portion of the probe elements.
13. The system of claim 1 , further including a second position sensor having at least two probe elements.
14. The system of claim 13 , wherein the position sensor and second position sensor are positioned at least partially offset with respect to each other along a direction of motion of the conductive material to produce at least partially orthogonal signals associated with the relative position of the conductive material with respect to the position sensor and the second position sensor.
15. The system of claim 1 , wherein the at least two probe elements are driven by a frequency source in the range of 10 MHz to 2 GHz.
16. A servo system for positioning a transducer head relative to a magnetic storage tape having at least one void formed therein, comprising:
a head assembly including a data transducer;
a sensor having a two dimensional array of probe elements, wherein the sensor gene rates a signal in response to an electrical measurement across the probe elements that varies in response to an interaction of at least two of the probe elements with the at least one void formed in a magnetic storage medium; and
a controller for adjusting the data transducer relative to the magnetic storage medium in response to the signal.
17. The system of claim 16 , wherein the probe elements include tips.
18. The system of claim 17 , wherein the tips have a diameter of approximately 6 μm and are spaced at a pitch of approximately 12 μm.
19. The system of claim 16 , wherein the probe elements include plates.
20. The system of claim 16 , wherein the signal is associated with a difference in current through at least a portion of the probe elements.
21. The system of claim 16 , wherein the signal is associated with a difference in potential of at least a portion of the probe elements.
22. The system of claim 16 , wherein the signal is associated with a change in capacitance of at least a portion of the probe elements.
23. The system of claim 16 , further including a second position sensor having at least two probe elements.
24. The system of claim 23 , wherein the position sensor and second position sensor are positioned at least partially offset with respect to each other along a direction of motion of the conductive material to produce at least partially orthogonal signals associated with the relative position of the conductive material with respect to the position sensor and the second position sensor.
25. The system of claim 16 , wherein the at least two probe elements are driven by a frequency source in the range of 10 MHz to 2 GHz.
26. A method for sensing the position of a conductive material having at least one void formed therein, the method comprising:
generating a signal associated with a measure across a two-dimensional array of probe elements positioned adjacent a conductive material having at least one void formed therein, wherein the signal is associated with the interaction of at least two of the probe elements with the conductive material and the at least one void;
determining a relative position of the conductive material with respect to the probe elements in response to the signal.
27. The method of claim 26 , wherein the conductive material includes a layer of a magnetic storage medium.
28. The method of claim 26 , wherein the voids are patterned longitudinally along the magnetic storage medium.
29. The method of claim 26 , wherein the probe is coupled to a recording head of a media drive.
30. The method of claim 26 , wherein the at least one void includes circular shaped depressions on the surface of the conductive material.
31. The method of claim 26 , wherein multiple voids are disposed on the surface of the conductive material with a pitch of approximately 24 μm and a diameter of 12 μm.
32. The method of claim 26 , wherein the at least one void includes a stripe on the surface of the conductive material.
33. The method of claim 26 , wherein the signal is associated with a difference in current through at least a portion of the probe elements.
34. The method of claim 26 , wherein the signal is associated with a difference in potential across at least a portion of the probe elements.
35. The method of claim 26 , wherein the signal is associated with a change in capacitance of at least a portion of the probe elements.
36. The method of claim 26 , wherein the probe elements include a first probe including at least two probe elements and a second probe including at least two probe elements.
37. The method of claim 36 , wherein the first probe and the second probe are positioned at least partially offset with respect to each other along a direction of motion of the conductive material to produce at least partially orthogonal signals associated with the relative position of the first probe and the second probe and the conductive material.
38. The method of claim 26 , wherein the at least two probes are driven by a frequency source in the range of 10 MHz to 2 GHz.
39. A method for positioning a transducer head relative to a magnetic storage tape having at least one void formed therein, the method comprising:
generating a signal associated with a measure across at least two probe elements of a two dimensional array of probe elements positioned adjacent a magnetic storage tape having at least one void formed therein, wherein the signal is associated with the interaction of the at least two probe elements with the magnetic storage tape and the at least one void; and
positioning a transducer head relative to the magnetic storage tape in response to the signal.
40. The method of claim 39 , wherein the at least one void form a servo track longitudinally along the magnetic storage tape.
41. The method of claim 39 , wherein the at least one void are disposed longitudinally along the magnetic storage tape at a pitch of approximately 24 μm and a diameter of approximately 12 μm.
42. The method of claim 39 , wherein the signal is associated with a difference in current through at least a portion of the probe elements.
43. The method of claim 39 , wherein the signal is associated with a difference in potential across at least a portion of the probe elements.
44. The method of claim 39 , wherein the signal is associated with a change in capacitance of at least a portion of the probe elements.
45. The method of claim 39 , wherein the probe elements include a first probe including at least two probe elements and a second probe including at least two probe elements.
46. The method of claim 45 , wherein the first probe and the second probe are positioned at least partially offset with respect to each other along a direction of motion of the conductive material to produce at least partially orthogonal signals associated with the relative position of the first probe and the second probe and the conductive material.