Method and system for tracking magnetic media with embedded optical servo tracks

• US 7,187,515 B2
• Filed: 02/05/2003
• Issued: 03/06/2007
• Est. Priority Date: 02/05/2003
• Status: Expired due to Term

• Current Assignee: Quantum Corporation (Chi Ko Investment Co., Ltd.)
• Original Assignee: Quantum Corporation (Chi Ko Investment Co., Ltd.)
• Inventors: Saliba, George
• Primary Examiner(s): TZENG, FRED
• Application Number:
  US10/359,365
• Publication Number:
  US 20050057846A1
• Time in Patent Office: 1,490 Days
• Field of Search: 360/77.03, 360/69, 360/77.12, 360/134, 360/135, 360/291, 360/53.1, 428/156, 428/323
• US Class Current: 360/77.12
• CPC Class Codes: G11B 5/58 with provision for moving the head for the purpose of maintaining alignment of the head relative to the record carrier during transducing operation, e.g. to compensate for surface irregularities of the latter or for track following spacing means incorporated in the head structure G11B5/187, G11B5/255, G11B5/3106
• CPC Class Codes: G11B 5/584 for track following on tapes

Abstract

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.

Claims

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.