Parallel servo with ultra high bandwidth off-track detection

• US 6,266,205 B1
• Filed: 05/06/1998
• Issued: 07/24/2001
• Est. Priority Date: 03/10/1998
• Status: Expired due to Term

• Current Assignee: Maxtor Corporation (Seagate Technology Holdings Plc)
• Original Assignee: Maxtor Corporation (Seagate Technology Holdings Plc)
• Inventors: Schreck, Erhard T., Guo, Lin
• Primary Examiner(s): Hudspeth, David
• Assistant Examiner(s): DAVIDSON, DAN
• Application Number:
  US09/073,600
• Time in Patent Office: 1,175 Days
• Field of Search: 360/77.08, 360/77.06, 360/77.02, 360/77.05, 360/77.11, 360/78.05
• US Class Current: 360/77.06
• CPC Class Codes: B82Y 10/00 Nanotechnology for information processing, storage or transmission, e.g. quantum computing or single electron logic
• CPC Class Codes: B82Y 25/00 Nanomagnetism, e.g. magnetoimpedance, anisotropic magnetoresistance, giant magnetoresistance or tunneling magnetoresistance
• CPC Class Codes: G11B 2005/0016 of magnetoresistive transducers
• CPC Class Codes: G11B 2005/3996 large or giant magnetoresistive effects [GMR], e.g. as generated in spin-valve [SV] devices
• CPC Class Codes: G11B 5/00813 magnetic tapes
• CPC Class Codes: G11B 5/012 Recording on, or reproducing or erasing from, magnetic disks G11B17/00, G11B19/00 take precedence
• CPC Class Codes: G11B 5/09 Digital recording
• CPC Class Codes: G11B 5/3948 the sensitive elements being active read-out elements
• CPC Class Codes: G11B 5/488 Disposition of heads G11B5/49, G11B5/52 take precedence
• CPC Class Codes: G11B 5/4886 relative to rotating disc
• CPC Class Codes: G11B 5/4969 Details for track selection or addressing
• CPC Class Codes: G11B 5/4992 Circuits
• CPC Class Codes: G11B 5/5534 Initialisation, calibration, e.g. cylinder "set-up"
• CPC Class Codes: G11B 5/59622 Gain control; Filters
• CPC Class Codes: G11B 5/59627 Aligning for runout, eccentricity or offset compensation G11B5/5534, G11B5/59677, G11B5/59688 take precedence
• CPC Class Codes: G11B 5/59644 Acquisition or selection of servo format from a system reference after track seek G11B5/5556
• CPC Class Codes: G11B 5/59683 for magnetoresistive heads

Abstract

A magnetic storage system having one or more rotating disks is disclosed. In a preferred embodiment, each rotating disk has two magnetic surfaces which each contain a number of tracks. Each track has one or more data regions and one or more embedded servo sectors. First and second transducers are respectively suspended over first and second tracks corresponding to first and second magnetic surfaces. The second transducer determines an off-track position with respect to the second track by reading from the data region of the second track. Once the off-track position is determined for the second transducer, that information is used to position the first transducer with respect to the first track and position the second transducer with respect to the second track as the first transducer writes to the first track. Furthermore, the first transducer is positioned at a correction rate that exceeds the rate at which the first transducer encounters embedded servo sectors in the first track. As a result, the first transducer reduces or avoids flying-blind as it writes to the disk.

Claims

1. A magnetic storage system having one or more rotating disks, comprising:

a plurality of tracks on each rotating disk;

one or more embedded servo sectors within each of the plurality of tracks;

a first transducer suspended above one of the plurality of tracks;

a second transducer; and

a circuit that provides a correction rate at which the position of the first transducer is adjusted, wherein the correction rate exceeds a rate at which the first transducer encounters the embedded servo sectors, and the correction rate is responsive to user data read by the second transducer.

2. The magnetic storage system of claim 1, wherein the first transducer is a dual-purpose transducer for both reading and writing.

3. The magnetic storage system of claim 1, wherein the first transducer includes multiple offset read elements.

4. The magnetic storage system of claim 1, wherein the first transducer includes one or more read elements and the read elements include magnetoresistive material.

5. The magnetic storage system of claim 1, further including:

two magnetic surfaces on each rotating disk, wherein there is at least a first magnetic surface and a second magnetic surface;

the first transducer operatively engaged with the first magnetic surface; and

the second transducer operatively engaged with the second magnetic surface, wherein the second transducer reads the user data from a data region of the second magnetic surface to provide positioning information to the first transducer as it writes to the first magnetic surface.

6. The magnetic storage system of claim 1, wherein:

each rotating disk has two magnetic surfaces;

the plurality of tracks are on both magnetic surfaces for each rotating disk;

the plurality of tracks are grouped to form a plurality of zones; and

each zone is paired with a corresponding zone on another magnetic surface.

7. The magnetic storage system of claim 6, wherein each zone is paired by comparing a geometry of a first zone matching track on a first magnetic surface with a geometry of a second zone matching track on a second magnetic surface, wherein the first zone matching track and the second zone matching track are generally located at a same radial distance from a center of the rotating disk.

8. The magnetic storage system of claim 1, wherein the rotating disks are magneto-optical disks.

9. A magnetic storage system having one or more rotating disks, comprising:

a first track and a second track, each including;

a data region, and

one or more embedded servo sectors;

a first transducer suspended over the first track; and

a second transducer suspended over the second track, wherein;

the second transducer determines an off-track position with respect to the second track by analyzing the data region of the second track without analyzing any other tracks, and the position of the first transducer with respect to the first track is adjusted based upon the off-track position determined by the second transducer.

10. The magnetic storage system of claim 9, wherein the second transducer is a dual-purpose transducer used for both reading and writing.

11. The magnetic storage system of claim 9, wherein the second transducer includes multiple offset read elements.

12. The magnetic storage system of claim 9, further including:

a first magnetic surface operatively engaged with the first transducer; and

a second magnetic surface operatively engaged with the second transducer.

13. The magnetic storage system of claim 9, further including a correction rate at which the position of the first transducer is adjusted, wherein the correction rate exceeds a rate at which the first transducer encounters embedded servo sectors.

14. The magnetic storage system of claim 9, wherein:

each rotating disk has two magnetic surfaces;

a plurality of tracks are on both magnetic surfaces for each rotating disk;

the plurality of tracks are grouped to form a plurality of zones; and

each zone is paired with a corresponding zone on another magnetic surface.

15. The magnetic storage system of claim 14, wherein each zone is paired by comparing a geometry of a first zone matching track on a first magnetic surface with a geometry of a second zone matching track on a second magnetic surface, wherein the first zone matching track and the second zone matching track are generally located at a same radial distance from a center of the rotating disk.

16. A magnetic storage system having one or more rotating disks, comprising:

a first track and a second track, the first track having a first data region and the second track having a second data region, the second data region having a magnetic center;

a first transducer; and

a second transducer suspended above the second track which determines a position for the second transducer relative to the magnetic center of the second track in response to only the second data region;

wherein the first transducer is positioned relative to the first track based upon analysis of the position of the second transducer with respect to the magnetic center of the second track, and the first transducer is positioned at a correction rate that exceeds a rate at which the first transducer encounters embedded servo sectors on the first track.

17. The magnetic storage system of claim 16, wherein the first transducer is positioned relative to the first track as it writes to the first data region based upon the analysis of the position of the second transducer with respect to the magnetic center of the second track.

18. The magnetic storage system of claim 16, further including:

a first magnetic surface operatively engaged with the first transducer; and

a second magnetic surface operatively engaged with the second transducer.

19. The magnetic storage system of claim 16, wherein the second transducer includes multiple offset read elements.

20. The magnetic storage system of claim 16, wherein the correction rate is a uniform pulse rate.

21. The magnetic storage system of claim 16, wherein:

each rotating disk has two magnetic surfaces;

a plurality of tracks are on both magnetic surfaces for each rotating disk;

the plurality of tracks are grouped to form a plurality of zones; and

each zone is paired with a corresponding zone on another magnetic surface.

22. The magnetic storage system of claim 16, wherein the magnetic center of the second track corresponds to a portion of the data region with a strongest magnetic signal.

23. A magnetic storage system having one or more rotating disks, comprising:

a first track and a second track, the first track having a first data region and the second track having a second data region, the second data region having a magnetic center;

a first transducer;

a second transducer suspended above the second track which determines a position for the second transducer relative to the magnetic center of the second track in response to only the second data region; and

a memory that stores a pairing of the first and second tracks in a look-up table;

wherein the first transducer is positioned relative to the first track based upon analysis of the position of the second transducer with respect to the magnetic center of the second track, each rotating disk has two magnetic surfaces, a plurality of tracks are grouped to form a plurality of zones, each zone is paired with a corresponding zone on another magnetic surface, each zone is paired by comparing a geometry of a first zone matching track on a first magnetic surface with a geometry of a second zone matching track on a second magnetic surface, and the first zone matching track on the first magnetic surface and the second zone matching track on the second magnetic surface are generally located at a same radial distance from a center of the rotating disk.

24. A method for positioning two or more transducers within a magnetic storage disk drive, comprising the steps of:

providing one or more disks, wherein each disk has two magnetic surfaces;

providing one or more tracks for each surface of each disk, wherein each track includes a data region;

grouping the plurality of tracks on each magnetic surface into a plurality of zones;

comparing a geometry of a first zone matching track within a first zone on the first magnetic surface to a geometry of a second zone matching track within a second zone on the second magnetic surface;

pairing a first transducer which writes to a first track on a first surface to a second transducer which reads from a second track on a second surface;

storing a pairing of the first and second tracks in a look-up table; and

positioning the first transducer, as it writes to the data region of the first track, based upon positioning information determined by the second transducer, as it reads from the data region of the second track without reading from any other track on the second surface.

25. The method for positioning two or more transducers of claim 24, further comprising a step of determining which two magnetic surfaces have most similar track geometries within the corresponding zone.

26. The method for positioning two or more transducers of claim 25, wherein the determining step resolves a pairing for the first transducer to the second transducer in the pairing step.

27. The method for positioning two or more transducers of claim 24, wherein the second transducer includes multiple read elements that are both laterally and longitudinally offset from one another.

28. A method for positioning two or more transducers within a magnetic storage disk drive, comprising the steps of:

providing one or more disks, wherein each disk has two magnetic surfaces;

providing one or more tracks for each surface of each disk, wherein each track includes a data region;

pairing a first transducer which writes to a first track on a first surface to a second transducer which reads from a second track on a second surface; and

positioning the first transducer, as it writes to the data region of the first track, based upon positioning information determined by the second transducer, as it reads from the data region of the second track using a read element that the second transducer uses during normal read operations and without reading from any other track on the second surface.

29. A method for positioning two or more transducers within a magnetic storage disk drive, comprising the steps of:

providing one or more disks, wherein each disk has two magnetic surfaces;

providing one or more tracks for each surface of each disk, wherein each track includes a data region;

pairing a first transducer which writes to a first track on a first surface to a second transducer which reads from a second track on a second surface; and

positioning the first transducer, as it writes to the data region of the first track, based upon positioning information determined by the second transducer, as it reads from the data region of the second track without reading from any other track on the second surface, wherein the first track and the second track are located at a same radial distance from a center of the one or more disks.

30. A magnetic storage device, comprising:

a magnetic media;

a first transducer for reading information from the magnetic media;

a second transducer; and

a circuit that adjusts a position of the first transducer at a correction rate that exceeds a rate at which the first transducer encounters embedded servo sectors on the magnetic media in response to user data read by the second transducer.

31. The magnetic storage device of claim 30, wherein the circuit adjusts the position of the first transducer at least three times while the first transducer is between adjacent ones of the embedded servo sectors on the magnetic media.

32. The magnetic storage device of claim 31, wherein the second transducer encounters second embedded servo sectors on a second magnetic media at the same rate that the first transducer encounters the embedded servo sectors on the magnetic media.

33. The magnetic storage device of claim 30, wherein the user data read by the second transducer is located in a data region on a single track on the second magnetic media.

34. The magnetic storage device of claim 30, wherein the correction rate is responsive to a read signal based on first and second analog read signals obtained from first and second laterally and longitudinally offset read elements, respectively, in the second transducer.

35. A magnetic storage device, comprising:

a first transducer that writes to a first data region on a first magnetic media, wherein the first data region is between first embedded servo sectors on the first magnetic media;

a second transducer that reads from a second data region on a second magnetic media to provide a read signal, wherein the second data region is between second embedded servo sectors on the second magnetic media; and

a circuit that positions the first transducer in response to the read signal while the first transducer writes to the first data region.

36. The magnetic storage device of claim 35, wherein the first and second magnetic media are located on opposing surfaces of a single disk.

37. The magnetic storage device of claim 35, wherein the circuit positions the first transducer multiple times while the first transducer continuously writes to the first data region.

38. The magnetic storage device of claim 37, wherein the second transducer reads from only the second data region to provide the read signal, and the second data region is only on a single track on the second magnetic media.

39. The magnetic storage device of claim 38, wherein the circuit simultaneously positions the first and second transducers in response to the read signal while the first transducer writes to the first data region.

40. A disk drive, comprising:

first and second disk surfaces, wherein the first disk surface includes a first track with first embedded servo sectors and first data regions, and the second disk surface includes a second track with second embedded servo sectors and second data regions;

a first transducer for reading from and writing to the first track;

a second transducer for reading from and writing to the second track, wherein the second transducer includes;

a first read element that provides a first read signal in response to information on the second track; and

a second read element that provides a second read signal in response to the information on the second track, wherein the first and second read elements are both laterally and longitudinally offset from each other; and

a circuit that compares the first and second read signals, adjusts the first and second read signals in response to the comparison, provides a combined read signal in response to the adjusted first and second read signals, and positions the first transducer in response to the combined read signal.

41. The disk drive of claim 40, wherein the circuit positions the first transducer as the first transducer writes to one of the first data regions.

42. The disk drive of claim 40, wherein the circuit positions the first transducer multiple times as the first transducer writes to one of the first data regions without encountering any of the first embedded servo sectors.

43. The disk drive of claim 40, wherein the circuit simultaneously positions the first and second transducers in response to the combined read signal.

44. The disk drive of claim 40, wherein the first and second read elements include magnetoresistive material.

45. The disk drive of claim 40, wherein the first and second read elements overlap laterally but do not overlap longitudinally.

46. The disk drive of claim 40, wherein the first and second read elements have identical dimensions.

47. The disk drive of claim 40, wherein the first and second read elements are located on an air bearing surface of a slider.

48. The disk drive of claim 40, further including means for positioning the first and second transducers in response to the first and second read signals.

49. The disk drive of claim 40, wherein the second transducer includes a third read element that provides a third read signal in response to the information on the second track, and the circuit provides the combined read signal in response to the first, second and third read signals.

50. The disk drive of claim 40, wherein the circuit adjusts the first and second read signals in response to detected lateral positions of the first and second read elements with respect to a magnetic center of the second track.

51. The disk drive of claim 50, wherein the circuit adjusts the first and second read signals by changing respective gains of the first and second read signals.

52. The disk drive of claim 50, wherein a transducer center is defined as a center of a sum of a lateral distance covered by the first and second read elements, a majority of the first read element and a minority of the second read element are on a first side of the transducer center, and a majority of the second read element and a minority of the first read element are on a second side of the transducer center opposite the first side.

53. The disk drive of claim 52, wherein the circuit increases a gain of the first read signal when the magnetic center is on the first side of the transducer center.

54. The disk drive of claim 53, wherein the circuit increases a gain of the second read signal when the magnetic center is on the second side of the transducer center.

55. The disk drive of claim 54, wherein the circuit decreases a gain of the first read signal when the magnetic center is on the second side of the transducer center.

56. The disk drive of claim 55, wherein the circuit decreases a gain of the second read signal when the magnetic center is on the first side of the transducer center.

57. The disk drive of claim 52, wherein the circuit increases a gain of the first read signal when the magnetic center is on the first side of the transducer center, and the circuit decreases a gain of the first read signal when the magnetic center is on the second side of the transducer center.

58. The disk drive of claim 57, wherein the circuit increases a gain of the second read signal when the magnetic center is on the second side of the transducer center, and the circuit decreases a gain of the second read signal when the magnetic center is on the first side of the transducer center.

59. The disk drive of claim 58, wherein the circuit combines the gain-adjusted first and second read signals to provide the combined read signal which is processed by a read channel in the disk drive.

60. A disk drive, comprising:

a first disk surface for storing data;

a second disk surface for storing data, wherein the first disk surface is separated from and substantially parallel to the second disk surface, and the first and second disk surfaces have substantially the same radius and, during operation, rotate about a common axis;

a first transducer for transferring data between the first disk surface and an exterior environment;

a second transducer for transferring data between the second disk surface and the exterior environment;

a multi-stage actuator for positioning the first and second transducers at desired locations over the first and second disk surfaces, wherein the multi-stage actuator includes a primary actuator for simultaneously moving the first and second transducers, a first microactuator for moving the first transducer without moving the second transducer, and a second microactuator for moving the second transducer without moving the first transducer; and

a circuit that positions the first transducer while the first transducer writes to the first disk surface in response to a read signal that the second transducer provides as the second transducer reads user data from the second disk surface, wherein the circuit positions the first transducer but not the second transducer in response to the read signal.

61. The disk drive of claim 60, wherein the circuit positions the first transducer multiple times while the first transducer continuously writes to a data region on the first disk surface between embedded servo sectors on the first disk surface.

62. The disk drive of claim 60, wherein the read signal is obtained from a single track on the second disk surface.

63. The disk drive of claim 60, wherein the first and second disk surfaces are opposing surfaces of a single magnetic disk.

64. A disk drive, comprising:

a first disk surface for storing data;

a second disk surface for storing data, wherein the first disk surface is separated from and substantially parallel to the second disk surface, and the first and second disk surfaces have substantially the same radius and, during operation, rotate about a common axis;

a first transducer for transferring data between the first disk surface and an exterior environment;

a second transducer for transferring data between the second disk surface and the exterior environment;

a multi-stage actuator for positioning the first and second transducers at desired locations over the first and second disk surfaces, wherein the multi-stage actuator includes a primary actuator for simultaneously moving the first and second transducers, a first microactuator for moving the first transducer without moving the second transducer, and a second microactuator for moving the second transducer without moving the first transducer; and

a circuit that positions the first transducer while the first transducer writes to the first disk surface in response to a read signal that the second transducer provides as the second transducer reads user data from the second disk surface, wherein the circuit positions the first transducer multiple times while the first transducer continuously writes to a data region on the first disk surface between embedded servo sectors on the first disk surface.

65. A method of positioning a transducer in a disk drive, comprising:

providing a first transducer for writing to a first disk surface;

providing a second transducer for reading from a second disk surface; and

positioning the first transducer as it writes to a first data region between first embedded servo regions on a first track on the first disk surface in response to a read signal provided by the second transducer as it reads from a second data region between second embedded servo sectors on a second track on the second disk surface.

66. The method of claim 65, including:

comparing geometries of the first and second tracks; and

selecting the second track in response to the comparing step.

67. The method of claim 66, wherein the comparing step is performed during manufacture of the disk drive.

68. The method of claim 66, wherein the comparing step is performed periodically after manufacture of the disk drive.

69. The method of claim 66, including:

storing an association between the first and second tracks in a look-up table in response to the comparing step;

determining that the first transducer shall be writing to the first track;

accessing the look-up table in response to the determining step; and

performing the selecting step in response to the accessing step.

70. A method of positioning a transducer in a disk drive, comprising:

providing a first transducer for reading and writing to and from a first disk surface that includes first and second zones of tracks;

providing a second transducer for reading and writing to and from a second disk surface that includes first and second zones of tracks;

providing a third transducer for reading and writing to and from a third disk surface that includes first and second zones of tracks;

positioning the first transducer as it writes to a track in the first zone on the first disk surface in response to a read signal provided by the second transducer as it reads from a track on the first zone on the second disk surface using a read element that the second transducer uses during normal read operations from the second disk surface and without reading from any other track on the second disk surface; and

positioning the first transducer as it writes to a track in the second zone on the first disk surface in response to a read signal provided by the third transducer as it reads from the second zone on the third disk surface using a read element that the third transducer uses during normal read operations from the third disk surface and without reading from any other track on the third disk surface.

71. The method of claim 70, wherein the first zones on the first, second and third disk surfaces are radially aligned with one another, and the second zones on the first, second and third disk surfaces are radially aligned with one another.

72. A method of positioning a transducer in a disk drive, comprising:

providing a first transducer for reading and writing to and from a first disk surface that includes first and second zones of tracks;

providing a second transducer for reading and writing to and from a second disk surface that includes first and second zones of tracks;

providing a third transducer for reading and writing to and from a third disk surface that includes first and second zones of tracks;

comparing geometries of tracks in the first zones on the first, second and third disk surfaces and selecting the first zone on the second disk surface to provide positioning information for the first zone on the first disk surface in response thereto;

comparing geometries of tracks in the second zones on the first, second and third disk surfaces and selecting the second zone on the third disk surface to provide positioning information for the second zone on the first disk surface in response thereto;

positioning the first transducer as it writes to a track in the first zone on the first disk surface in response to a read signal provided by the second transducer as it reads from a track on the first zone on the second disk surface; and

positioning the first transducer as it writes to a track in the second zone on the first disk surface in response to a read signal provided by the third transducer as it reads from the second zone on the third disk surface;

wherein the comparing steps are performed during manufacture of the disk drive.

73. A method of positioning a transducer in a disk drive, comprising:

providing a first transducer for reading and writing to and from a first disk surface that includes first and second zones of tracks;

providing a second transducer for reading and writing to and from a second disk surface that includes first and second zones of tracks;

providing a third transducer for reading and writing to and from a third disk surface that includes first and second zones of tracks;

comparing geometries of tracks in the first zones on the first, second and third disk surfaces and selecting the first zone on the second disk surface to provide positioning information for the first zone on the first disk surface in response thereto;

comparing geometries of tracks in the second zones on the first, second and third disk surfaces and selecting the second zone on the third disk surface to provide positioning information for the second zone on the first disk surface in response thereto;

positioning the first transducer as it writes to a track in the first zone on the first disk surface in response to a read signal provided by the second transducer as it reads from a track on the first zone on the second disk surface; and

positioning the first transducer as it writes to a track in the second zone on the first disk surface in response to a read signal provided by the third transducer as it reads from the second zone on the third disk surface;

wherein the comparing steps are performed periodically after manufacture of the disk drive.

74. A method of positioning a transducer in a disk drive, comprising:

providing a first transducer for reading from and writing to first tracks on a first disk surface, wherein the first tracks each contain servo sectors interspersed between data regions;

providing a second transducer for reading from and writing to second tracks on a second disk surface, wherein the second tracks each contain servo sectors interspersed between data regions; and

a positioning the first transducer multiple times as it writes to one of the data regions on one of the first tracks in response to multiple periodic correction signals responsive to the second transducer as it reads from one of the data regions on one of the second tracks without reading from any other tracks in the disk drive.

75. The method of claim 74, including positioning the first and second transducers simultaneously in response to the correction signals.

76. The method of claim 74, including positioning the first transducer without positioning the second transducer in response to the correction signals using a multi-stage actuator that includes first and second microactuators associated with the first and second transducers, respectively.

77. The method of claim 74, including providing the second transducer with first and second read elements that are both laterally and longitudinally offset from one another and providing the correction signals in response to first and second gain-adjusted read signals in response to the first and second read elements in response to the one of the data regions on the one of the second tracks.

78. The method of claim 74, including selecting the second transducer to provide the correction signals in response to a look-up table.

79. A magnetic storage system having one or more rotating disks, comprising:

a first track and a second track, each including;

a data region, and

one or more embedded servo sectors;

a first transducer suspended over the first track; and

a second transducer suspended over the second track, wherein;

the second transducer determines an off-track position with respect to the second track by analyzing the data region of the second track, and the position of the first transducer with respect to the first track is adjusted based upon the off-track position determined by the second transducer at a correction rate that exceeds a rate at which the first transducer encounters embedded servo sectors.

80. A magnetic storage system having one or more rotating disks, comprising:

a first track and a second track, the first track having a first data region and the second track having a second data region, the second data region having a magnetic center;

a first transducer; and

a second transducer suspended above the second track which determines a position for the second transducer relative to the magnetic center of the second track in response to user data on the second track;

wherein a position for the first transducer is adjusted at a correction rate that exceeds a rate at which the first transducer encounters embedded servo sectors on the first track in response to the user data.