Optical servo system for a tape drive

• US 6,236,529 B1
• Filed: 05/22/2000
• Issued: 05/22/2001
• Est. Priority Date: 12/01/1997
• Status: Expired due to Term

• Current Assignee: Storage Technologies Corporation (Oracle Corporation)
• Original Assignee: Storage Technologies Corporation (Oracle Corporation)
• Inventors: Leonhardt, Michael Lawrence, Wilson, Scott David
• Primary Examiner(s): Hudspeth, David
• Assistant Examiner(s): HABERMEHL, JAMES LEE
• Application Number:
  US09/577,017
• Time in Patent Office: 365 Days
• Field of Search: 360/77.12, 360/78.02, 360/75, 360/77.03, 369/44.11, 369/44.14
• 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 and wherein said second side of said tape is devoid of data fields for writing data thereon, said system comprising:

means for reflectively illuminating said optical servo features from said second side of said tape;

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. 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 and wherein said second side of said tape is devoid of data fields for writing data thereon, said system comprising the steps of:

reflectively illuminating said optical servo features from said second side of said tape;

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.

3. In combination:

a tape having regions of differing reflectivity on a side thereof;

a tape head having regions of differing reflectivity; and

an optical servo system that views an image of the tape and tape head to effectuate alignment between the tape and tape head, wherein the image is reflected from at least a portion of both the tape and the tape head.

4. 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 and wherein said second side of said tape is devoid of data fields for writing data thereon, said system comprising:

a light source positioned to reflect light off the second side of said tape;

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.

5. In combination:

a tape having regions of differing phase on a side thereof;

a tape head having regions of differing phase; and

an optical servo system that views an image of the tape and tape head to effectuate alignment between the tape and tape head, wherein the image is reflected from at least a portion of both the tape and the tape head.