Patent US3715524A successfully refreshed from Google Patents.
US3715524A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Electro-optical groove tracking apparatus for video reproducing system
Assignee: Zenith Electronics LLC
•
Filing: 1972-04-20
•
Granted: 1973-02-06
•
Expires: 1992-04-20
Abstract
Abstract Video information is stored optically along a helical track on a rotating disc over which an optical pick-up moves radially in correspondence with progressive displacement of a monitored portion of the track. To maintain constant alignment between the pick-up and the track regardless of deviations in the intended radial progression of either, a control signal is applied to an electromechanical transducer in order to vary the position of the pick-up transversely relative to the monitored track portion. Spaced parallel from the disc is a mask to span a plurality of track segments. All of the slits are oriented generally along those segments, and the number of slits is slightly different from the number of the segments in the width of the span. A generally collimated beam of light is projected through the slits and the portion of the disc which carries the segment. A balanced photodetector system responds to a moire'' pattern in the light which is projected through both the slits and the disc portion in order to develop a pair of signals which represent relative departure of the pick-up laterally from the monitored track length. A differential amplifier combines these signals into a control signal which is applied to the transducer to effect a compensatory variation in the position of the pick-up.
Inventors
- 👤 R Adler
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 12:13
CPC Classifications
G; G11; G11B; G11B7/00; G11B7/08; G11B7/09; G11B7/0901; H; H04; H04N; H04N5/00; H04N5/76; H04N5/84; H04N5/85
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
206 words
In a video reproducing system wherein video information is stored optically along a helical track on a rotating disc and an optical pick-up is moved radially of said disc in correspondence with progressive generally uniform radial displacement of a monitored portion of said track, guidance apparatus comprising: adjusting means responsive to a control signal for varying the position of said pick-up transversely relative to said monitored portion of track; a mask physically linked to said pick-up, parallel spaced from said disc and having a plurality of optical slits laterally spaced apart to span a plurality of segments of said track and all oriented generally along said segments, the number of said slits being slightly different from the number of said segments in the width of said span; means for projecting a generally collimated beam of light through said slits and the region of said disc carrying said segments; detection means responsive to a moire'' pattern in said light projected through said slits and disc region for developing signals representive of relative departure of said pickup laterally from said monitored track portion; and means responsive to said signals for developing said control signal in a manner to effect a compensatory variation in the position of said pickup.
Claim 2
Dependent Claim
206 words
In a video reproducing system wherein video information is stored optically along a helical track on a rotating disc and an optical pick-up is moved radially of said disc in correspondence with progressive generally uniform radial displacement of a monitored portion of said track, guidance apparatus comprising: adjusting means responsive to a control signal for varying the position of said pick-up transversely relative to said monitored portion of track; a mask physically linked to said pick-up, parallel spaced from said disc and having a plurality of optical slits laterally spaced apart to span a plurality of segments of said track and all oriented generally along said segments, the number of said slits being slightly different from the number of said segments in the width of said span; means for projecting a generally collimated beam of light through said slits and the region of said disc carrying said segments; detection means responsive to a moire'' pattern in said light projected through said slits and disc region for developing signals representive of relative departure of said pickup laterally from said monitored track portion; and means responsive to said signals for developing said control signal in a manner to effect a compensatory variation in the position of said pickup.
Claim 3
Dependent Claim
206 words
In a video reproducing system wherein video information is stored optically along a helical track on a rotating disc and an optical pick-up is moved radially of said disc in correspondence with progressive generally uniform radial displacement of a monitored portion of said track, guidance apparatus comprising: adjusting means responsive to a control signal for varying the position of said pick-up transversely relative to said monitored portion of track; a mask physically linked to said pick-up, parallel spaced from said disc and having a plurality of optical slits laterally spaced apart to span a plurality of segments of said track and all oriented generally along said segments, the number of said slits being slightly different from the number of said segments in the width of said span; means for projecting a generally collimated beam of light through said slits and the region of said disc carrying said segments; detection means responsive to a moire'' pattern in said light projected through said slits and disc region for developing signals representive of relative departure of said pickup laterally from said monitored track portion; and means responsive to said signals for developing said control signal in a manner to effect a compensatory variation in the position of said pickup.
Claim 4
Dependent Claim
206 words
In a video reproducing system wherein video information is stored optically along a helical track on a rotating disc and an optical pick-up is moved radially of said disc in correspondence with progressive generally uniform radial displacement of a monitored portion of said track, guidance apparatus comprising: adjusting means responsive to a control signal for varying the position of said pick-up transversely relative to said monitored portion of track; a mask physically linked to said pick-up, parallel spaced from said disc and having a plurality of optical slits laterally spaced apart to span a plurality of segments of said track and all oriented generally along said segments, the number of said slits being slightly different from the number of said segments in the width of said span; means for projecting a generally collimated beam of light through said slits and the region of said disc carrying said segments; detection means responsive to a moire'' pattern in said light projected through said slits and disc region for developing signals representive of relative departure of said pickup laterally from said monitored track portion; and means responsive to said signals for developing said control signal in a manner to effect a compensatory variation in the position of said pickup.
Claim 5
Dependent Claim
37 words
A video reproducing system as defined in claim 1 in which said adjusting means is a piezoelectric transducer mechanically coupled to said optical pick-up and responsive to said control signal for effecting physical movement of said pick-up.
Claim 6
Dependent Claim
28 words
A video reproducing system as defined in claim 1 in which said slits each have a radius approximately the same as the average radius of said helical track.
Claim 7
Dependent Claim
131 words
A video reproducing system as defined in claim 1 in which: said mask is spaced along said monitored portion of track from said pick-up; a beam of substantially collimated light is projected along a path generally parallel to said disc and in spatial alignment with said mask and said optical pick-up; said projecting means includes a partially reflecTive mirror disposed in the path of said beam for projecting a portion of said beam through said slits and the region of said disc carrying said segments; an optical element is disposed in the path of said beam for directing another portion thereof toward said monitored portion of said track; and a lens is included in said system for focusing said other portion of said beam upon said monitored portion of said track.
References Cited (Backward Citations)
US3245307A
Cited
US3361873A
Cited
US3391255A
Cited
US3454777A
Cited
US3530258A
Cited
US3673412A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-02-06 | 1976-08-07 | 1977-02-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-02-06 | 1980-08-07 | 1981-02-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-02-06 | 1984-08-07 | 1985-02-06 | $7700.00 | Window Closed / Lapsed |