EP0078060A1
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Method and apparatus for recovering information from a selected track on a record disc
Assignee: Discovision Associates
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Filing: 1982-10-27
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Granted: —
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Expires: 2002-10-27
Abstract
Abstract A method and apparatus for rapidly moving a reading beam of light radially relative to a rotating record disc, to impinge on a selected target track on the disc and recover information recorded on it. The apparatus first radially translates an optical system that directs the beam onto the disc at a relatively high speed until it is within a prescribed radial distance of the target track. Thereafter, an element of the optical system is controllably deflected such that the beam moves incrementally across a prescribed plurality of tracks during each disc revolution, until reaching the target track. The information recorded on each track includes a unique address signal, and movement of the beam relative to the disc is controlled according to the difference between the respective addresses of the track currently being scanned and the target track. If the apparatus fails to properly recover a track address signal, it estimates the address of the track currently being scanned, and updates its control of the beam's radial movement based on that estimate.
Inventors
- 👤 Gary Michael Giddings
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-29 12:05
CPC Classifications
G; G11; G11B; G11B19/00; G11B19/20; G11B21/00; G11B21/02; G11B21/08; G11B19/02; G11B19/04; G11B21/081; G11B21/083; G11B21/085; G11B25/00; G11B25/04; G11B27/00; G11B27/10; G11B27/102; G11B27/105; G11B27/19; G11B27/28; G11B27/30; G11B27/3027; G11B27/3036; G11B27/3054; G11B7/00; G11B7/08; G11B7/085; G11B7/08505; G11B7/08517; G11B7/09; G11B2220/00; G11B2220/20
Claims Analysis
Total Claims: 19
Claim 1
Independent Claim
124 words
Apparatus for recovering information from a selected target track of a plurality of substantially circular and concentric recording tracks on a record disc, the apparatus comprising: means for rotating the disc in a prescribed fashion; means for scanning the rotating disc to recover information recorded thereon; coarse positioning means for moving the scanning means at a prescribed radial velocity relative to the disc, toward the target track; and fine positioning means, operable after the coarse positioning means has moved the scanning means into the vicinity of the target track, for moving the scanning means incrementally across a prescribed plurality of tracks during each revolution of the disc, until reaching the target track, the scanning means then recovering the information recorded on the target track.
Claim 2
Dependent Claim
124 words
Apparatus for recovering information from a selected target track of a plurality of substantially circular and concentric recording tracks on a record disc, the apparatus comprising: means for rotating the disc in a prescribed fashion; means for scanning the rotating disc to recover information recorded thereon; coarse positioning means for moving the scanning means at a prescribed radial velocity relative to the disc, toward the target track; and fine positioning means, operable after the coarse positioning means has moved the scanning means into the vicinity of the target track, for moving the scanning means incrementally across a prescribed plurality of tracks during each revolution of the disc, until reaching the target track, the scanning means then recovering the information recorded on the target track.
Claim 3
Dependent Claim
67 words
Apparatus as defined in Claim l, wherein the fine positioning means includes: means for radially accelerating the scanning means relative to the disc, in the direction of the target track; means for counting the number of tracks crossed by the scanning means; and means for terminating radial movement of the scanning means relative to the disc, after the scanning means has crossed a prescribed plurality of tracks.
Claim 4
Dependent Claim
57 words
Apparatus as defined in Claim 2, wherein: the means for terminating operates during each revolution of the disc, after the scanning means has crossed a prescribed maximum number of tracks; and the means.for radially accelerating, means for counting, and means for terminating operate successively a prescribed number of times, until the scanning means reaches the target track.
Claim 5
Dependent Claim
68 words
Apparatus as defined in Claim 2, wherein the means for counting includes: a presettable decrementing counter; means for presetting a prescribed number into the decrementing counter; means for detecting when the scanning means'moves across a track and for decrementing the counter by one count at a time; and means for coupling a termination signal to the means for terminating when the count in the decrementing counter reaches zero.
Claim 6
Dependent Claim
48 words
Apparatus as defined in Claim 1, and further including means for determining when the scanning means is positioned within a prescribed number of tracks of the target track, and for terminating operation of the coarse positioning means and initiating operation of the fine positioning means at that time.
Claim 7
Dependent Claim
68 words
Apparatus as defined in Claim 5, wherein: the scanning means periodically produces a current track address signal indicating the address of the track currently being scanned; and the means for determining includes means for comparing the current track address signal with a signal indicating the target track address, to determine whether or not the scanning means is positioned within the prescribed number of tracks of the target track.
Claim 8
Dependent Claim
80 words
Apparatus as defined in Claim 1, wherein: the scanning means includes means for directing a beam of light at the rotating disc, to produce a modulated beam having an intensity that varies in accordance with the recorded information; the coarse positioning means includes motor means for moving the disc radially relative to the beam of light; and the fine positioning means includes beam deflection means for controllably deflecting the beam and thereby adjusting its point of impingement on the disc.
Claim 9
Dependent Claim
51 words
Apparatus as defined in Claim 7, wherein: the scanning means produces a tracking error signal indicating deviation of the beam of light from a selected track; and the fine positioning means is further selectively responsive to the tracking error signal, to controllably align the beam of light with the selected track.
Claim 10
Independent Claim
172 words
A method for recovering a video signal from a selected target track of a plurality of substantially circular and concentric recording tracks on a rotatable recording disc, the method comprising steps of: rotating the recording disc in a prescribed fashion; directing a reading beam of light onto a selected track on the rotating disc using an optical device, to produce a modulated beam having an intensity modulated by the video signal recorded on it; monitoring the modulated beam and producing a playback signal corresponding to its modulated intensity; radially moving the optical means at a relatively high velocity relative to the rotating disc, in the direction of the target track; terminating the step of radially moving after the reading beam has been moved to within a prescribed radial distance of the target track; and controllably deflecting the reading beam such that it moves incrementally across a prescribed plurality of tracks during each revolution of the disc, until reaching the target track, the step of monitoring thereafter recovering the video signal recorded thereon.
Claim 11
Independent Claim
172 words
A method for recovering a video signal from a selected target track of a plurality of substantially circular and concentric recording tracks on a rotatable recording disc, the method comprising steps of: rotating the recording disc in a prescribed fashion; directing a reading beam of light onto a selected track on the rotating disc using an optical device, to produce a modulated beam having an intensity modulated by the video signal recorded on it; monitoring the modulated beam and producing a playback signal corresponding to its modulated intensity; radially moving the optical means at a relatively high velocity relative to the rotating disc, in the direction of the target track; terminating the step of radially moving after the reading beam has been moved to within a prescribed radial distance of the target track; and controllably deflecting the reading beam such that it moves incrementally across a prescribed plurality of tracks during each revolution of the disc, until reaching the target track, the step of monitoring thereafter recovering the video signal recorded thereon.
Claim 12
Dependent Claim
64 words
A method as defined in Claim 9, wherein the step of controllably deflecting includes steps of: radially accelerating the reading beam relative to the disc, in the direction of the target track; counting the number of tracks crossed by the reading beam; and terminating radial movement of the reading beam relative to the disc, after the beam has crossed a prescribed plurality of tracks.
Claim 13
Dependent Claim
55 words
A method as defined in Claim 10, wherein: the step of terminating occurs during each revolution of the disc, after the reading beam has crossed a prescribed maximum number of tracks; and the steps of radially accelerating, counting, and terminating occur successively a prescribed number of times, until the reading beam reaches the target track.
Claim 14
Dependent Claim
62 words
A method as defined in Claim 10, wherein the step of counting includes steps of: presetting a prescribed number into a decrementing counter; detecting when the reading moves across a track and for decrementing the counter by one count at that time; and generating a termination signal to trigger the step of terminating when the count in the decrementing counter reaches zero.
Claim 15
Dependent Claim
78 words
A method as defined in Claim 9, wherein: each track on the recording disc records a video signal representing one video frame, with a unique track address signal located in the vertical interval; and the method further includes a step of determining when the reading beam has been moved to a position within a prescribed number of tracks of the target track, and terminating the step of radially moving and initiating the step of deflecting at that time.
Claim 16
Dependent Claim
79 words
A method as defined in Claim 13, wherein: the method further includes a step of monitoring the playback signal, to detect periodically a current track address signal indicating the address of the track currently being scanned; and the step of determining includes a step of comparing the current track address signal with a signal indicating the target track address, to determine whether or not the reading beam is positioned within the prescribed number of tracks of the target track.
Claim 17
Dependent Claim
190 words
In a method for recovering information from a selected target track of a plurality of substantially circular and concentric recording tracks on a record disc, wherein the information recorded on each track includes a unique track address signal, and wherein the method includes steps of rotating the disc in a prescribed fashion, moving an information recovery device radially relative to the disc, in the direction of the target track, updating a current track address register each time the information recovery device detects a track address signal, and adjusting the radial speed of the device in accordance with the difference between the target address and the address stored in the current track address register, an improvement comprising steps of: determining when the information recovery device fails to recover a recorded track address signal; monitoring the radial speed of the information recovery device relative to the disc; using the monitored radial speed to produce an estimate of the address of the track being scanned by the information recovery device when it is determined to fail to recover a recorded track address; and updating the current track address register with the address estimate.
Claim 18
Dependent Claim
190 words
In a method for recovering information from a selected target track of a plurality of substantially circular and concentric recording tracks on a record disc, wherein the information recorded on each track includes a unique track address signal, and wherein the method includes steps of rotating the disc in a prescribed fashion, moving an information recovery device radially relative to the disc, in the direction of the target track, updating a current track address register each time the information recovery device detects a track address signal, and adjusting the radial speed of the device in accordance with the difference between the target address and the address stored in the current track address register, an improvement comprising steps of: determining when the information recovery device fails to recover a recorded track address signal; monitoring the radial speed of the information recovery device relative to the disc; using the monitored radial speed to produce an estimate of the address of the track being scanned by the information recovery device when it is determined to fail to recover a recorded track address; and updating the current track address register with the address estimate.
Claim 19
Dependent Claim
95 words
An improvement as defined in Claim 15, wherein: the information recorded on the record disc includes a video signal, with each track recording one video frame, and with the target address signals located in the successive vertical intervals of the video signal; the information recovery device produces a playback signal corresponding to the information recovered from the disc; and the step of determining includes steps of detecting data in the successive vertical interval portions of the playback signal, and evaluating the detected data to determine whether or not it corresponds to a track address signal.,
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