Patent US3829612A successfully refreshed from Google Patents.
US3829612A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Video disc playback eddy current speed control system
Assignee: RCA Corp
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Filing: 1972-08-29
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Granted: 1974-08-13
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Expires: 1992-08-29
Abstract
Abstract A speed control system is provided for a video disc playback system. A motor is mechanically coupled to a conductive turntable and drives the turntable to rotate and thereby establish a relative motion between a video disc record mounted on the turntable and a pickup device. The free running speed of the turntable is above the normal operating speed required for proper operation of the playback system. An error signal representative of the speed of the relative motion between the disc record and the pickup device is applied to a magnetic field generating structure. The resulting magnetic field establishes eddy currents in the conductive turntable which creates a braking force which tends to oppose the rotation of the turntable.
Inventors
- 👤 B Beyers
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 14:14
CPC Classifications
G; G11; G11B; G11B19/00; G11B19/20; G11B19/24; H; H02; H02P; H02P29/00; H02P29/0016; H02P29/0022; Y; Y10; Y10S; Y10S388/00; Y10S388/923; Y10S388/93; Y10S388/932
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
228 words
In a video disc playback system wherein a prerecorded video signal is recovered from a disc record by a pickup device when relative motion is established between said disc record and said pickup device and wherein a predetermined speed of said relative motion is required for proper operation of said system, a speed control system comprising: a turntable structure for supporting said disc record, said turntable structure having a conductive portion; means including a motor coupled to said turntable for driving said turntable to rotate and thereby establish a relative motion between said disc record and said pickup device, the free running speed of said turntable causing the speed of said relative motion to be above said predetermined speed; means for adjusting the speed of rotation of said turntable to control the speed of said relative motion between said disc record and said pickup device; said adjusting means comprising means for generating a magnetic field which establishes eddy currents in said conductive portion which create a force tending to oppose the rotation of said turntable; means responsive to deviations of the speed of said relative motion from said predetermined speed for altering the duty cycle of energization of said magnetic field generating means to vary said rotation opposing force in a sense tending to reduce said deviations of the speed of said relative motion from said predetermined speed.
Claim 2
Dependent Claim
228 words
In a video disc playback system wherein a prerecorded video signal is recovered from a disc record by a pickup device when relative motion is established between said disc record and said pickup device and wherein a predetermined speed of said relative motion is required for proper operation of said system, a speed control system comprising: a turntable structure for supporting said disc record, said turntable structure having a conductive portion; means including a motor coupled to said turntable for driving said turntable to rotate and thereby establish a relative motion between said disc record and said pickup device, the free running speed of said turntable causing the speed of said relative motion to be above said predetermined speed; means for adjusting the speed of rotation of said turntable to control the speed of said relative motion between said disc record and said pickup device; said adjusting means comprising means for generating a magnetic field which establishes eddy currents in said conductive portion which create a force tending to oppose the rotation of said turntable; means responsive to deviations of the speed of said relative motion from said predetermined speed for altering the duty cycle of energization of said magnetic field generating means to vary said rotation opposing force in a sense tending to reduce said deviations of the speed of said relative motion from said predetermined speed.
Claim 3
Dependent Claim
41 words
A speed control system as defined in claim 1 wherein said duty cycle altering means is responsive to synchronizing pulse component portions of said video signal to determine the deviation of the speed of said relative motion from said predetermined speed.
Claim 4
Dependent Claim
134 words
A speed control system as defined in claim 2 wherein aid motor is energized from a source of alternating potential, and said duty cycle altering means includes a device having a first, second and control electrode, the first and second electrodes of said device operatively connected with said magnetic field generating means and said source of alternating potential, and the control electrode of said device responsive to said synchronizing pulse components of said video signal such that said device is biased into conduction at a phase angle in each cycle of said alternating potential which establishes an average current through said magnetic field generating means to produce a force which adjusts the speed of the rotation of said turntable to reduce the deviation of the speed of said relative motion from said predetermined speed.
Claim 5
Dependent Claim
27 words
A speed control system defined in claim 1 wherein said means for generating a magnetic field is an iron core inductor positioned adjacent said turntable conducTive portion.
Claim 6
Dependent Claim
63 words
A speed control system as defined in claim 4 wherein said device comprises a silicon controlled rectifier; said first and second electrodes constitute the anode and cathode of said silicon controlled rectifier; said inductor and said alternating potential source are serially connected between said anode and said cathode; and said synchronizing pulse components comprise the vertical synchronizing pulse components of the video signal.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-08-12 | 1978-02-11 | 1978-08-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-08-12 | 1982-02-11 | 1982-08-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-08-12 | 1986-02-11 | 1986-08-13 | $7700.00 | Window Closed / Lapsed |