US3989893A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Reproducing apparatus with drop out suppression circuit for audio and video signals
Assignee: US Philips Corp
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Filing: 1974-12-04
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Granted: 1976-11-02
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Expires: 1994-12-04
Abstract
Abstract An apparatus for reading a record carrier on which a combined video signal is recorded in a single track, in particular a disc-shaped record carrier on which the signal is recorded in optically coded form. In order to reduce the disturbing effect of dropouts on the eventually obtained sound signal, a portion of the the video signal is subjected to the action of a clamping circuit. Said clamping circuit normally transfers the applied modulated video signal unmodified. During a dropout the modulated video signal consisting of the modulated sound and pilot signal is clamped at its average value by means of said clamping circuit, so that a substantial improvement is obtained in respect of the sound signal. Thus, the length of time of sound signal clamping is minimized and the sound quality is improved.
Inventors
- 👤 Hendrik Eisema
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 22:51
CPC Classifications
H; H04; H04N; H04N9/00; H04N9/79; H04N9/87; H04N9/88; H04N9/80; H04N9/82; H04N9/83; H04N9/835
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
236 words
A dropout compensation apparatus for an apparatus for reading a disc-shaped record carrier optically encoded with a combined video signal containing a first carrier wave modulated with luminance information and a second carrier wave modulated with sound information, comprising a radiation sensitive detector means for converting radiation from said carrier into an electrical video signal, a dropout detector for providing a dropout indicator control signal, first coupling means for connecting at least part of said combined video signal to said dropout detector, controlled clamping circuit means having a signal input terminal, an output terminal and a control terminal for passing unaffected any signal on the signal input terminal of said clamping circuit means to the output terminal of said clamping circuit means in response to the absence of a dropout indicating control signal at the control terminal of said clamping circuit means and for clamping the signal on the output terminal of said clamping circuit means to the average value of the signal on the signal input terminal of said clamping circuit means in response to the presence of a dropout indicating control signal on the control terminal of said clamping circuit means, second coupling means for connecting said dropout indicating control signal from said dropout detector to said control terminal of said clamping circuit means, and third coupling means for connecting said second modulated carrier wave to the signal input terminal of said clamping means.
Claim 2
Dependent Claim
236 words
A dropout compensation apparatus for an apparatus for reading a disc-shaped record carrier optically encoded with a combined video signal containing a first carrier wave modulated with luminance information and a second carrier wave modulated with sound information, comprising a radiation sensitive detector means for converting radiation from said carrier into an electrical video signal, a dropout detector for providing a dropout indicator control signal, first coupling means for connecting at least part of said combined video signal to said dropout detector, controlled clamping circuit means having a signal input terminal, an output terminal and a control terminal for passing unaffected any signal on the signal input terminal of said clamping circuit means to the output terminal of said clamping circuit means in response to the absence of a dropout indicating control signal at the control terminal of said clamping circuit means and for clamping the signal on the output terminal of said clamping circuit means to the average value of the signal on the signal input terminal of said clamping circuit means in response to the presence of a dropout indicating control signal on the control terminal of said clamping circuit means, second coupling means for connecting said dropout indicating control signal from said dropout detector to said control terminal of said clamping circuit means, and third coupling means for connecting said second modulated carrier wave to the signal input terminal of said clamping means.
Claim 3
Dependent Claim
28 words
An apparatus as recited in claim 1, wherein said third coupling means also couples said first modulated carrier wave to the signal input terminal of said clamping means.
Claim 4
Dependent Claim
25 words
Apparatus as recited in claim 1, wherein said first coupling means comprises a filter passing only said first modulated carrier wave to said dropout detector.
Claim 5
Dependent Claim
25 words
Apparatus as recited in claim 2, wherein said first coupling means comprises a filter passing only said first modulated carrier wave to said dropout detector.
Claim 6
Dependent Claim
39 words
Apparatus as recited in claim 1, wherein said dropout detector comprises a peak detector for providing said dropout indicating control signal in response to a rise in the amplitude of the signal applied thereto exceeding a certain absolute value.
Claim 7
Dependent Claim
39 words
Apparatus as recited in claim 2, wherein said dropout detector comprises a peak detector for providing said dropout indicating control signal in response to a rise in the amplitude of the signal applied thereto exceeding a certain absolute value.
Claim 8
Dependent Claim
39 words
Apparatus as recited in claim 4, wherein said dropout detector comprises a peak detector for providing said dropout indicating control signal in response to a rise in the amplitude of the signal applied thereto exceeding a certain absolute value.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1979-11-02 | 1980-05-03 | 1980-11-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-11-02 | 1984-05-03 | 1984-11-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-11-02 | 1988-05-03 | 1988-11-02 | $7700.00 | Window Closed / Lapsed |