Servoing and formatting magnetic recording tape in an arcuate scanner system

• US 5,847,892 A
• Filed: 10/21/1997
• Issued: 12/08/1998
• Est. Priority Date: 11/13/1995
• Status: Expired due to Fees

• Current Assignee: Certance LLC (Chi Ko Investment Co., Ltd.)
• Original Assignee: Seagate Technology plc (Seagate Technology Holdings Plc)
• Inventors: Goker, Turguy
• Primary Examiner(s): Sniezek, Andrew L.
• Application Number:
  US08/955,022
• Time in Patent Office: 413 Days
• Field of Search: 360/71, 360/73.01, 360/73.04, 360/75, 360/77.01, 360/77.12, 360/83, 360/84, 360/76, 360/77.13, 360/77.15, 360/73.09, 360/73.12, 360/48
• US Class Current: 360/76
• CPC Class Codes: G11B 15/125 conditioned by the operating function of the apparatus
• CPC Class Codes: G11B 15/4677 using auxiliary signals, i.e. pilot signals
• CPC Class Codes: G11B 21/04 Automatic feed mechanism producing a progressive transducing traverse of the head in a direction which cuts across the direction of travel of the recording medium, e.g. helical scan , e.g. by lead-screw G11B19/20, G11B21/08 and G11B21/10 take precedence
• CPC Class Codes: G11B 21/086 on tapes
• CPC Class Codes: G11B 21/24 Head support adjustments
• CPC Class Codes: G11B 5/537 with all the heads disposed in a plane substantially parallel to the plane of the tape, e.g. for circular scanning
• 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

An arcuate scanner in accord with the invention records information on a longitudinal tape in a predetermined format. The format includes a top servo region and a lower servo region approximately twice as wide as one data track width. The top servo region contains a burst of recorded servo signal at a predetermined location. The lower servo region contains another burst of recorded servo signal at a predetermined location. Between each pair of top and lower servo regions, the information format includes two arcuate data tracks, containing a series of data blocks of a specified format. The locations of the servo bursts in the respective servo regions alternate between two lateral positions in adjacent servo tracks. During reading operations, a read head centered over one data track will pass both the servo regions around that data track and a portion of each of the servo regions around an adjacent track. A circuit samples the amplitude of the servo signal, taken during different time windows corresponding to passage over the various servo bursts in the two tracks. One or more relationships between the amplitudes of predetermined pairs of samples are used to produce one or more position error signals. Control elements, such as a tape drive motor and a position alignment controller (e.g. tilt motor) adjust the operation of the scanner system in response to the position error signal(s).

Claims

1. A method of controlling operations of a scanner system scanning a moving recording medium comprising the steps of:

passing a read head over a predetermined track recorded on the medium and partially overlapping a track adjacent the predetermined track on the medium;

determining a first time window and a second time window based on a detected passage of the read head over a detectable stripe that is prerecorded substantially along a length of the medium;

during the first time window in which the read head completely passes over a servo burst region of the predetermined track taking a first sample amplitude of servo burst signal from the read head;

during the second time window in which when the read head completely passes over a servo burst region of the adjacent track, taking a second sample amplitude of servo burst signal from the read head, wherein passage of the read head over the servo burst region of the adjacent track is excluded during the first time window and passage of the read head over the servo burst region of the predetermined track is excluded during the second time window; and

controlling a parameter of operation of the scanner system in response to a relationship of the first sample amplitude to the second sample amplitude.

2. A method as in claim 1, wherein the medium comprises a recording tape.

3. A method as in claim 1, wherein the step of controlling comprises adjusting the speed of the moving recording medium relative to a scanner head assembly containing at least the read head in response to the relationship of the first sample amplitude to the second sample amplitude.

4. A method as in claim 1, wherein the step of controlling comprises adjusting a positional alignment of an arcuate scanner head assembly comprising at least the read head relative to the moving recording medium.

5. A method as in claim 4, wherein the step of adjusting a positional alignment of the arcuate scanner head assembly comprises adjusting a tilt angle of the arcuate scanner head assembly.

6. A method as in claim 1, wherein the first time window precedes the second time window.

7. A method as in claim 1, wherein the second time window precedes the first time window.

8. A method as in claim 1, wherein the first and second time windows precede a time window during which the read head is expected to pass over a data region of the predetermined track.

9. A method as in claim 1, wherein the first and second time windows follow a time window during which the read head is expected to pass over a data region of the predetermined track.

10. A method as in claim 1, wherein the moving recording medium comprises a longitudinally moving magnetic tape.

11. A method as in claim 1, wherein:

the step of taking a first sample amplitude comprises sampling signals from the read head within one predetermined passband frequency range; and

the step of taking a second sample amplitude comprises sampling signals from the read head within said one predetermined passband frequency range.

12. A method as in claim 1, further comprising the steps of:

determining a third time window and a fourth time window based on the detected passage of the read head over the detectable stripe;

during the third time window when the read head passes over a second servo burst region of the predetermined track, taking a third sample amplitude of servo burst signal from the read head;

during the fourth time window when the read head passes over a servo burst region of the adjacent track, taking a fourth sample amplitude of servo burst signal from the read head; and

controlling a parameter of operation of the scanner system in response to a relationship of the third sample amplitude to the fourth sample amplitude.

13. A method as in claim 1, further comprising the steps of:

passing another read head over another predetermined track recorded on the medium and partially overlapping a track adjacent said another predetermined track on the medium;

during a third predetermined time window when said another read head passes over a servo burst region of said another predetermined track, taking a third sample amplitude of servo burst signal from said another read head;

during a fourth predetermined time window when said another read head passes over a servo burst region of the track adjacent said another track, taking a fourth sample amplitude of servo burst signal from said another read head; and

controlling a parameter of operation of the scanner system in response to a relationship of the third sample amplitude to the fourth sample amplitude.

14. An arcuate scanning system, comprising:

an arcuate scanner having a plurality of scanner heads, the arcuate scanner performing read and write operations on a recording tape;

a circuit responsive to read signals from one of the heads for detecting signals of a predetermined frequency;

a circuit responsive to read signals from the head for detecting a passage of the head over a detectable stripe that is prerecorded substantially along a length of the recording tape, and determining a first time window and a second time window based on the detected passage of the head over the detectable stripe;

a circuit for (1) sampling amplitude of the detected signals of a predetermined frequency during the first time window to produce a first sample amplitude and (2) sampling amplitude of the detected signals of a predetermined frequency during the second time window to produce a second sample amplitude, wherein the signals detected during the first time window, in which the read head completely passes over the servo burst region of the predetermined track, are excluded from being detected during the second time window, in which the read head completely passes over the servo burst region of the adjacent track, and wherein the signals detected during the second time window are excluded from being detected during the first time window;

a circuit responsive to a relationship between the first and second sample amplitudes for generating a position error signal; and

a control circuit for controlling at least one operational parameter of the arcuate scanning system in response to the position error signal.

15. A system as in claim 14, wherein the control circuit comprises:

a tape drive motor; and

a circuit controlling the speed of the tape drive motor in response to the position error signal.

16. A system as in claim 14, wherein the control circuit comprises:

a position alignment system coupled to the arcuate scanner to selectively align the arcuate scanner with regard to the recording tape; and

a circuit controlling the position alignment system in response to the position error signal.

17. A system as in claim 16, wherein the position alignment system comprises a tilt motor coupled to the arcuate scanner for selectively tilting the arcuate scanner at an angle with regard to the recording tape.