Optical servo system for a tape drive

• US 20010006437A1
• Filed: 02/05/2001
• Published: 07/05/2001
• Est. Priority Date: 12/01/1997
• Status: Active Grant

• Current Assignee: Storage Technologies Corporation (Oracle Corporation)
• Original Assignee: Storage Technologies Corporation (Oracle Corporation)
• Inventors: Leonhardt, Michael Lawrence, Wilson, Scott David
• Granted Patent: US 6,480,351 B2
• Time in Patent Office: Days
• US Class Current: 360/77.12
• CPC Class Codes: G11B 15/08 by photoelectric sensing G11B15/07 takes precedence
• CPC Class Codes: G11B 15/602 for track selection, acquisition or following
• CPC Class Codes: G11B 20/00086 Circuits for prevention of unauthorised reproduction or copying, e.g. piracy indicating unauthorised use of record carriers in general G11B23/28; scrambling for television signal recording H04N5/913; network architectures or network protocols for network security H04L63/00; cryptographic mechanisms or cryptographic arrangements for secret or secure communication H04L9/00
• CPC Class Codes: G11B 20/0021 involving encryption or decryption of contents recorded on or reproduced from a record carrier
• CPC Class Codes: G11B 21/085 with track following of accessed part
• CPC Class Codes: G11B 21/103 on tapes
• CPC Class Codes: G11B 2220/90 Tape-like record carriers
• CPC Class Codes: G11B 27/107 of operating tapes
• CPC Class Codes: G11B 27/26 by photoelectric detection, e.g. of sprocket holes
• CPC Class Codes: G11B 27/36 Monitoring, i.e. supervising the progress of recording or reproducing for digital recording G11B20/00 and s.gr.; for monitoring, testing or measuring of TV recorders of the type covered by H04N5/76 and subgroups, see H04N17/06
• CPC Class Codes: G11B 5/5508 Control circuits therefor G11B5/5513 takes precedence
• CPC Class Codes: G11B 5/584 for track following on tapes
• CPC Class Codes: G11B 5/588 by controlling the position of the rotating heads by controlling the speed of the record carrier G11B15/467; by controlling speed of the heads G11B15/473; by moving the transducing part of the head relative to the headwheel, in the direction of the scanning movement G11B15/1841

Abstract

The optical servo system for a tape drive that functions to align a read/write head with the data tracks written on a recording surface of a tape by reading optical servo tracks that are formed on the back side of the tape. This process decouples the magnetic recording of data on the recording surface of the tape from the optical servo system which makes use of servo tracks formed on the back side of the tape. The data storage capacity of the tape is increased since the entire recording surface of the tape is filled with data tracks and the precise alignment of the read/write head makes it possible to place the data tracks closer together. Regions of contrasting reflectivity or phase are also provided on a surface of the read/write head to enable the optical servo system to view an image of both the read/write head and the entire back side of the tape to thereby align the movable read/write head with the data tracks.

Claims

1. In a tape drive, a system for aligning a read/write head with a selected set of a plurality of data tracks written on a first side of a tape as said tape passes over said read/write head, wherein said tape also includes optical servo features formed on a second side of said tape, said system comprising:

means for reading said optical servo features from said second side of said tape; and

means, responsive to said read optical servo features, for aligning said read/write head with said selected set of a plurality of data tracks on said first side of said tape.

2. The system of

claim 1

, wherein said read/write head has a plurality of optical features formed thereon or affixed thereto, further comprising:

means for reading said optical features from said read/write head; and

wherein said means for aligning is responsive to said read optical servo features from said second side of said tape and said read optical features from said read/write head.

3. The system of

claim 2

wherein said means for reading said optical servo features and said means for reading said optical features comprise:

means for illuminating said optical servo features on said second side of said tape and said optical features of said read/write head;

means for reading an image of said optical servo features on said second side of said tape and said optical features of said read/write head;

means for generating electrical signals indicative of said optical servo features on said second side of said tape and said optical features on said read/write head from said read image.

4. The system of

claim 3

wherein said means for reading said optical servo features and said means for reading said optical features further comprise:

means for focusing said optical servo features on said second side of said tape and said optical features on said read/write head on to an imaging device to obtain electrical signals indicative of said image.

5. The system of

claim 3

, wherein said means for aligning comprises:

means, responsive to data track position data received from a controller of said tape drive, for identifying a position of said selected set of said plurality of data tracks in said plurality of data tracks;

means, responsive to said generated electrical signals, for determining a position offset between said read/write head and said selected set of said plurality of data tracks.

6. The system of

claim 5

, wherein said means for aligning further comprises:

means, responsive to said means for determining, for generating a position error signal to indicate a direction and magnitude of said position offset.

7. The system of

claim 6

wherein said means for aligning further comprises:

means, responsive to said position error signal, for moving said read/write head to adjust said alignment of said selected set of said plurality of data tracks of said tape and said read/write head.

8. The system of

claim 1

, wherein said second side of said tape has formed thereon auxiliary information from the class of tape auxiliary information including but not limited to:

encryption/authentication data, tape identification data, maintenance information, read only data, said system further comprising;

means for reading said auxiliary information from said second side of said tape; and

means for transmitting said read auxiliary data to a controller of said tape drive.

9. In a tape drive, a method for aligning a read/write head with a selected set of a plurality of data tracks written on a first side of a tape as said tape passes over said read/write head, wherein said tape also includes optical servo features formed on a second side of said tape, said system comprising the steps of:

reading said optical servo features from said second side of said tape;

aligning, in response to said read optical servo features, said read/write head with said selected set of a plurality of data tracks on said first side of said tape.

10. The method of

claim 9

, wherein said read/write head has a plurality of optical features formed thereon or affixed thereto, further comprising the step of:

reading said optical features from said read/write head; and

wherein said step of aligning is responsive to said read optical servo features from said second side of said tape and said read optical features from said read/write head.

11. The method of

claim 10

wherein said step of reading said optical servo features and said step of reading said optical features comprise:

illuminating said optical servo features on said second side of said tape and said optical features of said read/write head;

reading an image of said optical servo features on said second side of said tape and said optical features of said read/write head; and

generating electrical signals indicative of said optical servo features on said second side of said tape and said optical features on said read/write head from said read image.

12. The method of

claim 11

wherein said step of reading said optical servo features and said step of reading said optical features further comprise:

focusing said optical servo features on said second side of said tape and said optical features on said read/write head on to an imaging device to obtain electrical signals indicative of said image.

13. The method of

claim 11

, wherein said step of aligning comprises:

identifying, in response to data track position data received from a controller of said tape drive, a position of said selected set of said plurality of data tracks in said plurality of data tracks; and

determining, in response to said generated electrical signals, a position offset between said read/write head and said selected set of said plurality of data tracks.

14. The method of

claim 13

, wherein said step of aligning further comprises:

generating, in response to said step of determining, a position error signal to indicate a direction and magnitude of said position offset.

15. The method of

claim 14

wherein said step of aligning further comprises:

moving, in response to said position error signal, said read/write head to adjust said alignment of said selected set of said plurality of data tracks of said tape and said read/write head.

16. The method of

claim 9

, wherein said second side of said tape has formed thereon auxiliary information from the class of tape auxiliary information including but not limited to:

encryption/authentication data, tape identification data, maintenance information, read only data, said method further comprising the steps of;

reading said auxiliary information from said second side of said tape;

transmitting said read auxiliary data to a controller of said tape drive.