Servo methods and systems using existing data structures and medium edge position
View Patent ↗The present invention provides servo systems and accompanying methods for determining the relative position of a transducer head to a magnetic storage tape utilizing existing data structures on the magnetic storage tape and the position of the tape edge. In one example, a method for positioning a transducer head relative to a magnetic storage medium includes sensing a read signal from a read element associated with a transducer head, the read signal in response to a reference data track stored on a magnetic storage medium, optically sensing a position of an edge of the storage medium, and repositioning the transducer head relative to the storage medium in response to the read signal and the position of the edge of the storage medium.
1. A method for positioning a transducer head relative to a magnetic storage medium, comprising:
writing data tracks to a magnetic storage medium with a transducer head;
generating a read signal from a read element of the transducer head, the read signal in response to the last previously written data track;
optically sensing a position of an edge of the storage medium; and
repositioning the transducer head relative to the storage medium in response to the read signal and the position of the edge of the storage medium.
2. The method of claim 1 , wherein a characteristic of the read signal varies as a function of offset between the reference track and the read element.
3. The method of claim 2 , wherein the characteristic includes one or more of an error signal value, noise signal, average amplitude, average energy, k-bit value, and error rate value.
4. The method of claim 1 , wherein the read signal includes a signal quality parametric that varies as a function of offset between the read element and the reference data track, and the transducer head is repositioned based on the signal quality parametric.
5. The method of claim 1 , wherein the read element is a dedicated servo read element configured to read a reference data track as the transducer head access an active data track.
6. The method of claim 1 , further comprising writing a data track adjacent the reference data track.
7. The method of claim 1 , wherein optically sensing the position of the edge of the storage medium, comprises:
illuminating a window formed by a transmissive portion of a mask and an edge of the storage medium, wherein the mask is in a fixed spatial relationship to the transducer head; and
detecting an intensity of light passing through the window.
8. The method of claim 7 , repositioning the transducer head based on the intensity of the detected light passing through the window.
9. The method of claim 7 , wherein the transmissive portion of the mask includes an aperture.
10. The method of claim 7 , further comprising illuminating a second window formed by a second transmissive portion of the mask and a second edge of the storage medium.
11. The method of claim 7 , further comprising:
illuminating a third window formed by a third transmissive portion of the mask having a width greater than the width of the storage medium and opposing edges of the storage medium; and
detecting an intensity of light passing through the third window.
12. The method of claim 1 , wherein optically sensing the position of the edge of the storage medium, comprises:
illuminating a first mask and a second mask; and
detecting an intensity of light passing through the first mask and the second mask with a detector, wherein the first mask is stationary with respect to the transducer head, and the second mask is stationary with respect to the detector.
13. The method of claim 12 , wherein the detector has at least two sensing elements.
14. The method of claim 12 , wherein one of the first mask and the second mask includes two spatially complementary patterns, and the other of the first mask and the second mask includes a pattern corresponding to one of the spatially complementary patterns.
15. The method of claim 12 , wherein one of the first mask and the second mask includes a pattern of transmissive sections and non-transmissive sections.
16. The method of claim 1 , wherein optically sensing the position of the edge of the storage medium, comprises:
illuminating an edge of the storage medium thereby creating a diffraction pattern;
imaging the diffraction pattern onto a mask; and
detecting the diffraction pattern after passing through the mask.
17. The method of claim 16 , repositioning the transducer head based on a characteristic of the detected diffraction pattern.
18. The method of claim 1 , wherein the data track comprises user data.
19. A head positioning servo system, comprising:
a transducer head including a read element and a write element;
a light source for illuminating an edge of a magnetic storage medium;
a detector for detecting light from the light source illuminating the edge of the magnetic storage medium; and
a controller for adjusting the position of the transducer head in response to the detected light and a read signal from the read element, the read signal in response to a data track stored on the magnetic storage medium, wherein the data track comprises the last previously written data track recorded by the write element of the transducer head.
20. The system of claim 19 , wherein the read element is in a spatially fixed relationship to a write element such that alignment of the read element with at least a portion of the reference data track aligns the write element adjacent the reference data track.
21. The system of claim 19 , wherein a characteristic of the read signal varies as a function of offset between the reference track and the read element.
22. The system of claim 20 , wherein the characteristic includes one or more of an error signal value, noise signal value, average amplitude, average energy, k-bit value, and error rate value.
23. The system of claim 19 , wherein the read signal includes a signal quality parametric that varies as a function of offset between the read element and the reference data track.
24. The system of claim 19 , further comprising an optically encoded mask disposed between the light source and the detector.
25. The system of claim 19 , further comprising a first mask and a second mask disposed between the light source and the detector, wherein the first mask is stationary with respect to the transducer head and the second mask is stationary with respect to the detector.
26. The system of claim 19 , further comprising a mask positioned to create a window formed by a transmissive portion of a mask and an edge of the storage medium, wherein the mask is in a fixed spatial relationship to the transducer head, and the detector detects an intensity of light passing through the window.
27. The system of claim 26 , wherein the controller adjusts the position of the transducer head in response to the intensity of the detected light passing through the window.
28. The system of claim 26 , wherein the transmissive portion of the mask includes an aperture.
29. The system of claim 26 , further comprising a second window formed by a second transmissive portion of the mask and a second edge of the storage medium.
30. The system of claim 26 , further comprising a third window formed by a third transmissive portion of the mask having a width greater than the width of the storage medium and opposing edges of the storage medium.
31. The system of claim 19 , further comprising a first mask and a second mask, wherein the first mask is stationary with respect to the transducer head, and the second mask is stationary with respect to the detector, and the detector detects light an intensity of light passing through the first mask and the second mask.
32. The system of claim 31 , wherein the detector has at least two sensing elements.
33. The system of claim 31 , wherein one of the first mask and the second mask includes two spatially complementary patterns, and the other of the first mask and the second mask includes a pattern corresponding to one of the spatially complementary patterns.
34. The system of claim 31 , wherein one of the first mask and the second mask includes a pattern of transmissive sections and non-transmissive sections.
35. The system of claim 19 , further including mask having a diffraction pattern, the detector detects light diffracted from the edge of the tape and imaged onto the mask.
36. The system of claim 19 , wherein the data track comprises user data.