Magnetically biased tilting roller bearing tape guidance

• US 8,270,114 B2
• Filed: 02/08/2008
• Issued: 09/18/2012
• Est. Priority Date: 02/08/2008
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Argumedo, Armando Jesus, Bui, Nhan Xuan, Dyer, William Marvin, Hancock, Reed Alan, Harper, David Howard Flores, Imaino, Wayne Isami, Judd, Kevin Bruce
• Primary Examiner(s): Renner, Craig A.
• Assistant Examiner(s): POLO, GUSTAVO D
• Application Number:
  US12/028,649
• Publication Number:
  US 20090201608A1
• Time in Patent Office: 1,684 Days
• Field of Search: 360/93, 360/95, 360/130.21, 242/346, 242/615, 242/615.2, 242/615.3, 242/615.4, 226/190, 226/191, 226/194, 226/196.1
• US Class Current: 360/130.21
• CPC Class Codes: G11B 15/60 Guiding record carrier guiding devices structurally associated with magazines or cassettes G11B23/04

Abstract

In one embodiment, a tape movement constraint for a tape drive system, comprises a tiltable tape roller bearing having a roller barrel biased in a first position on a pivot axis, using magnetic attraction between a movable magnet and a return path structure of magnetically permeable material. The roller barrel is pivoted on the pivot axis by conducting current through a fixed coil to generate a magnetic field which is conducted by the return path structure to interact with the magnetic field of the magnet. At least a portion of any air bearing between the moving tape and the barrel surface is quenched using grooves formed in the barrel surface. Other embodiments are described and claimed.

Claims

1. A tape movement constraint for a tape drive system for a tape, comprising:

a base having a first support frame;

a coil supported by said first support frame and adapted to conduct an electric current to generate a magnetic field wherein said first support frame includes a return path structure formed of a magnetically permeable material, and positioned adjacent said coil to conduct said magnetic field generated by said coil;

a second support frame pivotally coupled to said first support frame;

a first permanent magnet supported by said second support frame wherein said magnet is positioned facing said return path structure; and

a tape roller barrel rotatably supported by said second support frame, said roller barrel being positioned along a tape path;

wherein magnetic attraction between said magnet and said return path structure biases said second support frame and said roller barrel in a first position relative to said first support frame and wherein current conducted through said coil generates a magnetic field which is conducted by said return path structure to interact with the magnetic field of said magnet which causes said second support frame and said roller barrel to pivot relative to said first support frame as a function of the magnitude and direction of said current through said coil.

2. The constraint of claim 1 wherein said tape drive system is adapted to move said tape along said tape path in a longitudinal direction across a tape head, said tape having tracks extending in said longitudinal direction, said tape subject to transient movement in a lateral direction with respect to said longitudinal direction, said constraint further comprising:

a tape position sensor positioned to detect the lateral position of the tape; and

a controller responsive to the tape position sensor and adapted to control the current through said coil to tilt the roller barrel to control the lateral position of the tape in response to the tape position sensor.

3. The constraint of claim 2 wherein said roller barrel has a grooved surface adapted to contact and engage a surface of the tape as said roller barrel rotates.

4. The constraint of claim 1 further comprising a second permanent magnet supported by said second support frame wherein said second magnet is positioned facing said return path structure and wherein said second support frame is pivotally coupled to said first support frame at a pivot point located between the first and second magnets.

5. The constraint of claim 1 wherein said second support frame includes a magnet holder adapted to hold said magnet, said constraint further comprising a roller bearing track positioned around and supported by said magnet holder and engaging said roller barrel, wherein said roller barrel is adapted to rotate on said roller bearing track around said magnet holder of said second support frame.

6. The constraint of claim 4 wherein said second support frame includes a magnet holder adapted to hold said first and second magnets, said constraint further comprising first and second roller bearing tracks positioned around and supported by said magnet holder and engaging said roller barrel with said pivot point located between said first and second roller bearing tracks, wherein said roller barrel is adapted to rotate on said roller bearing tracks around said magnet holder of said second support frame.

7. The constraint of claim 4 wherein said roller barrel has a center position in a lateral direction and said pivot point defines a pivot axis aligned with said center position.

8. The constraint of claim 6 wherein said return path structure formed of a magnetically permeable material includes a core around which said coil is wound, and first and second parallel members, each member being disposed at an end of said core, said permanent magnets and said magnet holder extending between said members of said return path structure.

9. The constraint of claim 6 wherein each roller bearing track defines an interior opening, and wherein said return path structure formed of a magnetically permeable material includes a core around which said coil is wound, and first and second parallel members, each member being disposed at an end of said core, and extending through the openings of said roller bearing tracks, said permanent magnets and said magnet holder extending between said members of said return path structure.

10. The constraint of claim 9 wherein said second support frame structure includes a swing arm extending around said first support frame and having two ends, each end being pivotally coupled to said first support frame, said magnet holder being coupled to said swing arm to pivot with said swing arm.

11. The constraint of claim 10 wherein each magnet has a face facing said magnetic return structure, each face being divided into portions of opposite magnetic polarity.

12. The constraint of claim 10 further comprising first and second magnet assemblies, each magnet assembly having a plurality of magnets and a face facing said magnetic return structure, each face being divided into portions of opposite magnetic polarity wherein said first magnet assembly includes said first permanent magnet and said second magnet assembly includes said second permanent magnet.

13. A method, comprising:

rotating a tape roller barrel by engaging a surface of the tape roller barrel with a longitudinally moving magnetic tape;

biasing said roller barrel in a first position on a pivot axis relative to a base support frame, using magnetic attraction between a first permanent magnet and a return path structure of magnetically permeable material wherein said magnet is coupled to said roller barrel and said return path structure is coupled to said base support frame;

sensing the lateral position of the moving tape; and

tilting the rotating roller barrel on said pivot axis relative to said base support frame in response to the sensed lateral position of the moving tape to control the lateral position of the moving tape, said tilting including conducting current through a coil to generate a magnetic field which is conducted by said return path structure to interact with the magnetic field of said magnet which causes said roller barrel to pivot on said pivot axis as a function of the magnitude and direction of said current through said coil.

14. The method of claim 13 further comprising quenching at least a portion of any air bearing between the moving tape and the barrel surface using grooves formed in the barrel surface.

15. The method of claim 13 wherein said coil of said current conducting is at least partially disposed within said roller barrel.

16. The method of claim 15 wherein said rotating includes using a roller bearing track positioned around and supported by a magnet holder adapted to hold said magnet and engaging said roller barrel, wherein said roller barrel is adapted to rotate on said roller bearing track around said magnet holder in response to engagement of the surface of the tape roller barrel with the longitudinally moving magnetic tape.

17. The method of claim 13 wherein said pivot axis is aligned with a center position of said roller barrel surface in a lateral direction.

18. The method of claim 13 wherein said biasing further includes using magnetic attraction between a second permanent magnet and said return path structure of magnetically permeable material wherein said second magnet is coupled to said roller barrel and wherein said tilting further includes conducting current through said coil to generate a magnetic field which is conducted by said return path structure to interact with the magnetic field of said second magnet which causes said roller barrel to pivot on said pivot axis located between said first and second magnets, as a function of the magnitude and direction of said current through said coil.

19. The method of claim 18 wherein each magnet has a face facing said return path structure, each face being divided into portions of opposite magnetic polarity.

20. The method of claim 18 wherein said first and second magnets are assembled into first and second magnet assemblies, respectively, each magnet assembly having a plurality of magnets and a face facing said magnetic return structure, each face being divided into portions of opposite magnetic polarity.