Method and apparatus for controlling the position of a transported web

• US 4,692,819 A
• Filed: 04/16/1986
• Issued: 09/08/1987
• Est. Priority Date: 08/31/1984
• Status: Expired due to Term

• Current Assignee: Ampex Corporation (Delta Information Systems, Inc.)
• Original Assignee: Ampex Corporation (Delta Information Systems, Inc.)
• Inventors: Steele, Robert
• Primary Examiner(s): NOT, DEFINED
• Application Number:
  US06/854,711
• Time in Patent Office: 510 Days
• Field of Search: 226/27, 360/72.1, 360/72.2, 360/72.3, 360/73, 360/74.1, 360/74.4
• US Class Current: 360/72.1
• CPC Class Codes: G11B 15/18 Driving; Starting; Stopping; Arrangements for control or regulation thereof G11B15/56 takes precedence
• CPC Class Codes: G11B 15/1875 adaptations for special effects or editing signal processing or indexing therefor G11B27/00
• CPC Class Codes: G11B 15/602 for track selection, acquisition or following
• CPC Class Codes: G11B 2220/90 Tape-like record carriers
• CPC Class Codes: G11B 27/107 of operating tapes
• CPC Class Codes: G11B 27/17 using electrical sensing means see provisionally also G11B27/13
• CPC Class Codes: G11B 27/32 on separate auxiliary tracks of the same or an auxiliary record carrier
• CPC Class Codes: G11B 27/323 Time code signal, e.g. on a cue track as SMPTE- or EBU-time code
• CPC Class Codes: G11B 27/34 Indicating arrangements indicating means incorporated in magazine or cassette G11B23/046 and G11B23/0875; indicating measured values in general G01D

Abstract

An apparatus and method for controlling the position of a web containing location identifying information thereon. In particular, a means for measuring displacement of the web independent of the location information is employed to measure the displacement of the web in a cyclic manner such that the measuring cycle is in the expected displacement intervals between identifying information. A difference between a desired position of the web determined by an operator controlled reference displacement position of the web is determined, and used for controlling the position of the web to the desired position.

Claims

1. Apparatus for controlling the position of a web relative to a path along which it is transported, the web having a number of markers thereon from which positions on the web relative to the path can be determined, comprising:

first means for transporting the web along the path;

second means for detecting markers on the web as the web is transported along the path;

third means independent of the markers responsive to the transport of the web along the path for generating first signals indicative of lengths of displacement of the transported web along the path, the third means generating a number of first signals for a selected length of displacement of the transported web greater than the number of markers detected during such displacement;

fourth means responsive to the detection of markers and to first signals for generating a second signal indicative of the position of the web along the path corresponding to the length of displacement of the transported web indicated by said first signals following detection of a marker;

fifth means for generating a reference signal representative of a selected position along the web relative to the a marker;

sixth means responsive to the reference signal and the second signal for generating an error signal representative of a difference between the position of the web and the selected position; and

,

seventh means responsive to the error signal for controlling the first means to eliminate the difference between the position of the web and the selected position.

12. Apparatus as recited in claim 1, wherein said sixth means further comprises:

eighth means responsive to the magnitude of the difference between the reference signal and the second signal for generating a speed signal representative of a desired speed;

ninth means responsive to the reference signal and to the second signal for generating a sign signal indicative of the sign of the difference between the reference signal and the second signal;

counting means responsive to the sign signal for counting the occurrences of the sign signal, and generating an indication when the number of occurrences of the sign signal has not exceeded a predetermined number; and

tenth means responsive to said counting means for generating an error signal having a magnitude responsive to said first means, and a sign responsive to said second means.

13. Apparatus as recited in claim 12 wherein said seventh means further comprises means for controlling the speed of the transport means responsive to the magnitude of the error signal in a direction responsive to the sign of the error signal.

2. A method for controlling the position of a web relative to a path along which it is transported, the web having a number of markers thereon from which positions on the web relative to the path can be determined, comprising the steps of:

transporting the web along the path;

detecting markers on the web as the web is transported along the path;

generating first signals independent of the markers and indicative of lengths of displacement of the transported werb along the path, the number of first signals generated for a selected length of displacement of the transported web being greater than the number of markers detected during such displacement;

generating a second signal responsive to the detection of markers and to first signals, indicative of the position of the web along the path corresponding to the length of displacement of the transported web indicated by said first signals following detection of a marker;

generating a reference signal representative of a selected position along the web relative to a marker;

generating an error signal responsive to the reference signal and to the second signal, representative of a difference between the position of the web and the selected position; and

,

controlling the transport of the web responsive to the error signal to eliminate the difference between the positioned web and the selected position.

3. Apparatus for controlling the position of a magnetic tape relative to a path along which it is transported, the magnetic tape having a number of markers thereon from which positions on the magnetic tape relative to the path can be determined, comprising:

means for transporting the web along the path;

transducing means for detecting markers on the web as the web is transported along the path;

tachometer means independent of the markers responsive to the transport of the magnetic tape along the path for generating first signals indicative of lengths of displacement of the transported magnetic tape along the path, the tachometer means generating a number of first signals for a selected length of displacement of the transported magnetic tape greater than the number of markers detected during such displacement;

counter means responsive to the detection of markers and to first signals for generating a second signal indicative of the position of the magnetic tape along the path corresponding to the length of displacement of the transported web indicated by said first signals following detection of a marker;

means for generating a reference signal representative of a selected position along the magnetic tape relative to the a marker;

means responsive to the reference signal and the second signal for generating an error signal representative of a difference between the position of the magnetic tape and the selected position; and

,

means responsive to the error signal for controlling the first means to eliminate the difference between the position of the magnetic tape and the selected position.

4. Apparatus as recited in claim 3, wherein the markers are time code information.

5. Apparatus as recited in claim 3, wherein the markers are control track information.

6. Apparatus for controlling the position of a magnetic tape relative to a path along which it is transported with respect to a video transducing means, the magnetic tape having a number of markers thereon from which positions on the magnetic tape relative to the path can be determined, comprising:

means for transporting the web along the path;

marker transducing means for detecting markers on the magnetic tape as the magnetic tape is transported along the path;

tachometer means independent of the markers responsive to the transport of the magnetic tape along the path for generating first signals indicative of lengths of displacement of the transported magnetic tape along the path, the tachometer means generating a number of first signals for a selected length of displacement of the transported web greater than the number of markers detected during such displacement;

counter means responsive to the detection of markers and to first signals for generating a second signal indicative of the position of the magnetic tape with respect to the video transducing means along the path corresponding to the length of displacement of the transported magnetic tape indicated by said first signals following detection of a marker;

means for generating a reference signal representative of a selected position along the magnetic tape with respect to the video transducer means relative to the a marker;

means responsive to the reference signal and the second signal for generating an error signal representative of a difference between the position of the magnetic tape with respect to the video transducer means and the selected position; and

,

means responsive to the error signal for controlling the first means to eliminate the difference between the position of the magnetic tape relative to the video transducing means and the selected position.

7. Apparatus as recited in claim 6, wherein the markers are time code information.

8. Apparatus as recited in claim 6, wherein the markers are control track information.

9. Apparatus for controlling the position of a magnetic tape relative to a path along which it is transported with respect to a video transducing means, the magnetic tape having a number of markers thereon from which positions on the magnetic tape relative to the path can be determined, comprising:

means for transporting the magnetic tape along the path;

marker transducing means for detecting markers on the magnetic tape as the magnetic tape is transported along the path;

tachometer means independent of the markers responsive to the transport of the magnetic tape along the path for generating first signals indicative of lengths of displacement of the transported magnetic tape along the path, the third means generating a number of first signals for a selected length of displacement of the transported magnetic tape greater than the number of markers detected during such displacement;

counter means responsive to the detection of markers and to first signals for generating a second signal indicative of the position of the magnetic tape with respect to the video transducing means along the path corresponding to the length of displacement of the transported magnetic tape with respect to the video transducing means indicated by said first signals following detection of a marker;

means for generating a reference signal representative of a selected position along the magnetic tape with respect to the video transducing means relative to the a marker;

means responsive to the reference signal and the second signal for generating an error signal representative of a difference between the position of the magnetic tape with respect to the video transducing means and the selected position; and

,

means responsive to the error signal for controlling the transport means to eliminate the difference between the position of the magnetic tape and the selected position so that the velocity of the magnetic tape is responsive to a magnitude of the displacement of the magnetic tape relative to the transducing means from the desired position.

10. Apparatus as recited in claim 9, wherein the markers are time code information.

11. Apparatus as recited in claim 10, wherein the markers are control track information.

14. Apparatus for transporting a movable web along a path so as to position a desired location on the movable web to a fixed point along the path of the movable web, said apparatus comprising:

means for producing a first signal indicating a current location relative to the fixed point of said web according to one of a plurality of periodic location indicators located contiguously with said web;

means for producing a second signal, independently of said periodic location indicators, indicating said current location of said web relative to said periodic location indicators;

means for producing a control signal in response to said first signal and said second signal such that said control signal reflects a diference in position between said desired location and said current location; and

means for transporting said web to said desired location to the fixed point in response to said control signal.

15. Apparatus for positioning a transportable web of claim 14 wherein said second signal indicates said current position with higher resolution than said first signal.

16. Apparatus for positioning a transportable web of claim 14 wherein said second signal comprises tachometer pulses outputted by said means for positioning.

17. Apparatus for the determining a distance between a selected location on a transportable web and a fixed point along the web'"'"'s path of travel, said apparatus comprising:

means for generating a first signal indicating the distance between the selected location on the web and the fixed point according to one of a plurality of periodic location indicators located contiguously with the web;

means for generating a second signal, independently of the periodic location indicators, indicating the distance between the selected location on the web and the one of the periodic location indicators;

means for generating a location signal in response to the first signal and the second signal such that said location signal reflects the location of said web.

18. Method for the determining of a distance between a selected location on a transportable web and a fixed point along the web'"'"'s path of travel, comprising the steps of:

generating a first signal indicating the distance between the selected location on the web and the fixed point according to one of a plurality of periodic location indicators located contiguously with the web;

generating a second signal, independently of the periodic location indicators, indicating the distance between the selected location on the web and the one of the periodic location indicator;

generating a location in response t the first signal and the second signal such that said location signal reflects the location of said web.