Method and system for tracking magnetic media with embedded optical servo tracks
View Patent ↗A method and system for tracking storage media is provided that includes directing light through a first major side of a magnetic recording tape, wherein the tape includes optically detectable indicia embedded within the tape during formation of the indicia. At least a portion of the light may be detected after passing through the first side of the tape, and a change in the position of the tape based on the detected light may be determined.
1. A method for tracking storage media, comprising:
directing light through a first major side of a magnetic recording tape, wherein the tape includes optically detectable indicia embedded within the tape, the indicia formed by a laser directed through a first layer to a servo layer of the tape, the first layer disposed on a side of the servo layer opposite a magnetic storage layer of the tape;
detecting at least a portion of the light after passing through the first side of the tape; and
determining a change in the position of the tape based on the detected light.
2. The method of claim 1 , wherein a change in the position of the tape is determined by measuring the intensity of the detected light.
3. The method of claim 1 , wherein a change in the position of the tape is determined by measuring a change in the phase of the detected light.
4. The method of claim 1 , wherein a change in the position of the tape is determined by measuring a change in the transmission of the light through the first side of the tape and an opposite second side of the tape.
5. The method of claim 1 , wherein a change in the position of the tape is determined by measuring a change in the reflection of the light from the optical indicia.
6. The method of claim 1 , wherein light is detected from a second major side of the tape opposite the first side of the tape.
7. The method of claim 1 , further including at least one of reading or writing data to a magnetic recording layer from the first side of the tape.
8. The method of claim 1 , wherein the light includes an ultra violet light source.
9. The method of claim 1 , wherein the light includes an infrared light source.
10. The method of claim 1 , wherein the light produces a beam of light with a cross-sectional size smaller than a cross-sectional size of the indicia.
11. The method of claim 1 , wherein the light includes two or more beams of light.
12. The method of claim 11 , wherein the two or more beams of light overlay at least partially the indicia.
13. The method of claim 11 , wherein the two or more beams of light are detected separately.
14. The method of claim 11 , further including producing a control signal associated with detection of the two or more beams of light, wherein the control signal indicates movement of the tape.
15. The method of claim 1 , further including producing a control signal associated with the change in the position of the tape.
16. The method of claim 15 , wherein the control signal controls a servomechanism to adjust a magnetic recording head.
17. The method of claim 1 , wherein the indicia include a plurality of marks aligned with substantially equal spacing along a linear length of the tape.
18. The method of claim 1 , wherein the indicia include a plurality of marks aligned in tracks with substantially equal spacing along a linear dimension of the tape and substantially equal spacing between the tracks in the lateral dimension of the tape.
19. The method of claim 18 , wherein the indicia in the lateral dimension are off-set with respect to each other.
20. The method of claim 18 , wherein the indicia in the lateral dimension are off-set with respect to each by approximately 7 degrees.
21. A method for reading storage media including a magnetic data track and optically detectable indicia, comprising:
moving a magnetic tape with optically detectable indicia embedded within the tape, the indicia formed by a laser directed through a first layer to a servo layer of the tape during formation, the first layer disposed on a side of the servo layer opposite a magnetic storage layer of the tape;
projecting light through a portion of said magnetic tape to the indicia;
detecting at least a portion of the light transmitted through a portion of the magnetic tape;
producing a signal associated with the detected light; and
moving the position of the magnetic recording head in response to the signal.
22. The method of claim 21 , wherein the projected light is reflected from the indicia to a greater degree than the surrounding tape.
23. The method of claim 21 , wherein a change in the position of the tape is determined by measuring a change in the transmission of the light through a first major side of the tape and an opposite second major side of the tape.
24. The method of claim 21 , wherein a change in the position of the tape is determined by measuring a change in the reflection of the light from the optical indicia.
25. The method of claim 21 , wherein the phase of the projected light is changed by the indicia.
26. The method of claim 21 , further including measuring the intensity of the detected light transmitted through a portion of the magnetic tape.
27. The method of claim 21 , wherein the signal is used as feedback in a servo control system to determine the direction to move the magnetic recording head.
28. The method of claim 21 , wherein the signal is used as feedback in a servo control system to determine the magnitude to move the magnetic recording head.
29. The method of claim 21 , wherein the light includes three optical beams that overlay selected portions of the indicia.
30. The method of claim 29 , further including detecting the intensity of the three optical beams and operating a servo control system in a push-pull tracking mode.
31. The method of claim 21 , further including positioning the magnetic head and an optical head on opposites sides of the tape, wherein the magnetic head and the optical head are in a fixed relationship.
32. The method of claim 21 , further including positioning the magnetic head and an optical head on the same side of the tape, wherein the magnetic head and the optical head are in a fixed relationship.
33. A system for at least one of reading and writing data to one or more tracks on a magnetic recording medium comprising:
a magnetic recording medium including optically detectable indicia embedded within the tape, the indicia formed by a laser directed through a first layer to a servo layer of the tape during formation of the indicia, the first layer disposed on a side of the servo layer opposite a magnetic storage layer of the tape;
a magnetic data head for at least reading or writing data to the recording medium;
a light source positioned to project a pattern of light through said recording medium to the indicia;
a detector capable of detecting the pattern of light generated from said laser light source; and
a servo controller, wherein the servo controller moves the magnetic data head based on a change in the pattern of light detected by the detector.
34. The system of claim 33 , wherein said recording medium includes a magnetic recording tape.
35. The system of claim 33 , wherein the light source includes a laser.
36. The system of claim 33 , wherein the light source includes an ultraviolet laser.
37. The system of claim 33 , wherein the light source includes an infrared laser.
38. The system of claim 33 , wherein the magnetic head and the detector are in a fixed relationship with respect to each other.
39. The system of claim 33 , wherein the magnetic head and the detector are positioned on the same side of the recording medium.
40. The system of claim 33 , wherein the magnetic head and the detector are positioned on opposite sides of the recording medium.
41. The system of claim 33 , wherein the detector produces a signal associated with the detected light.
42. The system of claim 41 , wherein the signal is used as feedback in a servo control system to determine the direction to move the magnetic recording head.
43. The system of claim 33 , wherein the detected light includes a pattern of spots.
44. The system of claim 43 , wherein the detector produces a signal associated with the pattern of spots.
45. The system of claim 44 , wherein the signal is used as feedback in a servo control system to determine the direction to move the magnetic recording head.
46. The system of claim 44 , wherein the signal is used as feedback in a servo control system in a push-pull tracking mode.
47. The system of claim 33 , wherein the detector produces a signal as a function of the intensity of the light incident thereon.