Method and apparatus for recovering information from a videodisc
First Claim
1. A method for manipulating a track reader for recovering information from a selected target track of a plurality of spiralling and substantially circular information tracks or concentric circular information tracks on a record disc, each said track containing at least in part a unique track identifying code, said method comprising the steps of:
- (a) generating a target track identifying code that matches the track identifying code of said target track;
(b) rotating the disc in a prescribed fashion;
(c) scanning the disc with the track reader at a prescribed radial velocity relative to the disc, toward the target track to recover information recorded thereon including track identifying codes;
(d) comparing recovered track identifying codes with said target track identifying code and detecting the difference therebetween;
(e) scanning continuously toward said target track until said comparing and detecting step indicates that the recovered track identifying code is within a fixed range of the target track identified code;
(f) thereafter moving the track reader incrementally within said range relative to said disc across a prescribed number of tracks during each revolution of the disc, toward the target track;
(g) upon passing the target track by detection in said comparing and detection step, that the difference between the recovered track identifying code and the target track identifying code is increasing, reversing the radial scanning direction;
(h) continuing said incremental scanning while continuing to detect the difference between the recovered track identifying code and the target track identifying code, and continuing to reverse the radial direction of movement upon each detection of an increasing difference between the recovered track identifying code and the target track identifying code until a match is made therebetween, and in the absence of a match in a first prescribed period of time, incrementing the target track identifying code by a fixed value;
(i) continuing said incremental scanning toward said target track until a match between the recovered track identifying code and the incremented target track identifying code is found; and
(j) after a match is found, ceasing the relative radial movement across the disc and recovering the information from the arrived at track.
1 Assignment
0 Petitions
Accused Products
Abstract
A system for recovering information from a videodisc and performing special functions which enhance the operational character of the system. To increase the reliability of landing at or near a target track, provisions are made to search for a track adjacent a target track whose track identifier has been obliterated. Further, a method and means for stepping forward or reverse one field at a time is disclosed. Another aspect of the invention concerns a capability to respond to a random command instruction resulting in subsequent functioning of the system in a random manner. Yet a further aspect of the invention is related to controlled jumping of one or more tracks during vertical blanking time to produce unique forward or backward motions; multiples of playing speed, both forward and reverse, and visual special effects can be realized using the multiple track jumping feature. Finally, a method and means are described which permit synchronous transmission of video from a videodisc to an external using device.
68 Citations
10 Claims
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1. A method for manipulating a track reader for recovering information from a selected target track of a plurality of spiralling and substantially circular information tracks or concentric circular information tracks on a record disc, each said track containing at least in part a unique track identifying code, said method comprising the steps of:
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(a) generating a target track identifying code that matches the track identifying code of said target track; (b) rotating the disc in a prescribed fashion; (c) scanning the disc with the track reader at a prescribed radial velocity relative to the disc, toward the target track to recover information recorded thereon including track identifying codes; (d) comparing recovered track identifying codes with said target track identifying code and detecting the difference therebetween; (e) scanning continuously toward said target track until said comparing and detecting step indicates that the recovered track identifying code is within a fixed range of the target track identified code; (f) thereafter moving the track reader incrementally within said range relative to said disc across a prescribed number of tracks during each revolution of the disc, toward the target track; (g) upon passing the target track by detection in said comparing and detection step, that the difference between the recovered track identifying code and the target track identifying code is increasing, reversing the radial scanning direction; (h) continuing said incremental scanning while continuing to detect the difference between the recovered track identifying code and the target track identifying code, and continuing to reverse the radial direction of movement upon each detection of an increasing difference between the recovered track identifying code and the target track identifying code until a match is made therebetween, and in the absence of a match in a first prescribed period of time, incrementing the target track identifying code by a fixed value; (i) continuing said incremental scanning toward said target track until a match between the recovered track identifying code and the incremented target track identifying code is found; and (j) after a match is found, ceasing the relative radial movement across the disc and recovering the information from the arrived at track. - View Dependent Claims (2, 3, 4, 5, 6)
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7. Apparatus for recovering information from a selected target track of a plurality of spiralling and substantially circular information tracks or concentric circular information tracks on a record disc, each said track containing at least in part a unique track identifying code, said apparatus comprising:
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means for generating a target track identifying code that matches the track identifying code of said target track; means for rotating the disc in a prescribed fashion; a track reader for scanning the rotating disc to recover information recorded thereon; coarse positioning means for moving the track reader at a prescribed radial velocity relative to the disc, toward the target track; means for comparing recovered track identifying codes with said target track identifying code; means for detecting the difference between said recovered track identifying codes and said target track identifying code; fine positioning means, responsive to said detecting means and operable after the coarse positioning means has moved the track reader into within a number L of tracks from the target track, for moving the track reader incrementally across a prescribed number of tracks during each revolution of the disc, toward the target track; means for reversing the radial direction of radial scanning movement upon said detecting means detecting that the difference between the recovered track identifying code and the target track identifying code is increasing, said means for reversing the radial direction of scanning movement continuing to reverse the radial direction of scanning movement upon each detection of an increasing difference between the recovered track identifying code and the target track identifying code until a match is made therebetween by said comparing means; means for incrementing the target track identifying code by a fixed value in the absence of a match between the recovered track identifying code and the target track identifying code in a first prescribed period of time; said fine positioning means continuing to move said track reader incrementally across said prescribed number of tracks during each revolution of the disc toward said target track, whereupon said means for comparing compares recovered track identifying codes with the incremented target track identifying code until a match is made therebetween; said apparatus including terminating means for ceasing said relative radial movement when a match is made, said track reader operable to then recover the information recorded on the track whose identifying code matches the incremented target track identifying code. - View Dependent Claims (8, 9, 10)
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Specification