Method and apparatus for transporting a recording medium with an adaptive velocity change profile
First Claim
1. A method of controlling the transport of a tape relative to a reference point along a path of said tape, said tape being transported by a tape transport mechanism in accordance with a velocity change profile which changes with a changing distance separating said reference point from a selected location on said tape, said velocity change profile being determined by a selected parameter of the tape transport mechanism, comprising the steps of:
- providing and storing sets of velocity change profile values, each set pertaining to one velocity profile determined by a different value of said selected parameter;
monitoring an actual value of said selected parameter when the tape is being transported on said transport mechanism; and
selecting one set of said velocity change profile values corresponding to said monitored value of said selected parameter to control the speed of said transport mechanism for transporting the selected location on said tape to said reference point.
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Accused Products
Abstract
An adaptive velocity change profile for control of a video tape transport apparatus during a cue mode. The tape transport apparatus moves the video tape to a cue point in the shortest time available by adapting a deceleration velocity change profile to the actual ballistics of transport of the tape. When in a cue mode, the transport uses a commanded velocity signal generator to produce digital numbers which are applied as a reference speed signal to a velocity servo driving the takeup reel of the transport. For distances separating a selected frame location on the tape from the cue point greater than a predetermined distance, the commanded velocity is the maximum available from the transport. For distances to the cue point less than the predetermined distance, the commanded velocity is generated from an adaptive cue profile which decelerates the transport of the tape quickly as the selected frame location approaches the cue point without overshooting the mark. The deceleration velocity change profile is optimized as according to the distance separating the selected frame location from the cue point and the measured ballastics of transport of the tape. The measured ballistics of transport of tape varies according to variances in inertial loading represented by transport direction, tape reel size, and cue location with respect to tape pack distribution. The difference between velocity values for optimized profiles of the maximum and minimum inertial loading is proportioned depending upon the measured inertial loading to generate the commanded velocity.
121 Citations
27 Claims
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1. A method of controlling the transport of a tape relative to a reference point along a path of said tape, said tape being transported by a tape transport mechanism in accordance with a velocity change profile which changes with a changing distance separating said reference point from a selected location on said tape, said velocity change profile being determined by a selected parameter of the tape transport mechanism, comprising the steps of:
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providing and storing sets of velocity change profile values, each set pertaining to one velocity profile determined by a different value of said selected parameter; monitoring an actual value of said selected parameter when the tape is being transported on said transport mechanism; and selecting one set of said velocity change profile values corresponding to said monitored value of said selected parameter to control the speed of said transport mechanism for transporting the selected location on said tape to said reference point. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method of controlling a tape transport mechanism for moving a tape relative to a reference point along a path of said tape to a cue point location on the tape during a cue mode of operation, using a signal recorded at regular intervals along the length of said tape, said tape being moved in accordance with a velocity change profile which changes with a changing distance separating said reference point from said cue point location, said velocity change profile being determined by a selected parameter of the tape transport mechanism, comprising the steps of:
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selecting a cue point location on the tape; determining a distance along the tape separating the cue point location from the reference point; providing and storing sets of velocity change profile values, each set pertaining to one velocity profile determined by a different value of said selected parameter, said velocity change profile values of each set changing with a distance separating said cue point location from said reference point; monitoring an actual value of said selected parameter when said tape is being transported by said transport mechanism; and moving the tape along said path at a velocity determined by a changing distance separating said selected location from said reference point and by a set of velocity change profile values determined by said monitored value of said selected parameter and stopping said tape when said cue point location reaches said reference point.
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12. A method of controlling the velocity of transport of a video tape having video information recorded thereon in the form of consecutive frames, comprising the steps of:
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selecting a desired frame location recorded on the tape, representing a cue point which is to be moved during a cue mode of operation to a reference location along a path of said tape and stopped; determining a distance along said path separating said cue point from said reference location; providing a command indicative of desired speed of said transport mechanism to effect a change in said desired speed when said distance reaches a predetermined value; providing and storing sets of velocity change profile values, each set pertaining to one velocity profile determined by a different value of a selected parameter of the tape transport mechanism, said velocity change profile values of each set changing with said distance; monitoring an actual value of said selected parameter when said tape is being transported by said transport mechansim; and
whereinsaid command is provided in accordance with a set of velocity change profile values determined by said monitored value of said selected parameter.
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13. A control apparatus for controlling a transport mechanism for transporting a tape relative to a reference point along a path of said tape, in accordance with a velocity change profile which changes with a changing distance separating said reference point from a selected location on said tape, said velocity change profile being determined by a selected parameter of the tape transport mechanism, comprising;
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means for providing and storing sets of velocity change profile values, each set pertaining to one velocity profile determined by a different value of said selected parameter; means for monitoring an actual value of said selected parameter during the transport of said tape by said transport mechanism; and means for controlling the speed of said transport mechanism in accordance with a set of velocity change profile values corresponding to said monitored value of said selected parameter, for transporting the selected location on said tape to said reference point. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26)
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27. An apparatus for controlling a transport mechanism for transporting a tape having video information recorded thereon, relative to a reference point along a path of said tape, in accordance with a velocity change profile which changes with a changing distance separating said reference point from a selected cue point location on the tape, said velocity change profile being determined by an inertial load provided by a total amount of tape on said transport mechanism, comprising:
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means for determining a distance along said path separating said selected cue point location from said reference point; means for generating for said detected distances a set of minimum speed reference signal values corresponding to a maximum inertial load, provided by a largest total amount of tape, and storing said minimum values in a first memory means; means for generating for said detected distances a set of incremental speed reference signal values corresonding to a known increment in said inertial load, provided by a known increment in said total amount of tape, and storing said incremental values in a second memory means; means for monitoring an actual total amount of tape on said transport mechanism correponding to an actual inertial load; and means for combining said stored minimum speed reference signal values with a proportion of said stored incremental speed reference signal values, where said proportion corresponds to ratio of a difference between said maximum inertial load and said actual inertial load to said known increment in said inertial load, to obtain a set of velocity profile values corresponding to said actual inertial load.
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Specification