US3566025A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Device for the automatic gain control and clamping of the black level for television receivers
Assignee: US Philips Corp
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Filing: 1968-02-01
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Granted: 1971-02-23
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Expires: 1988-02-01
Abstract
Abstract In a circuit for generating an automatic gain control voltage and for clamping the black level of television signals, a diode has one electrode connected to a video input circuit. Line flyback pulses are applied to the other electrode of the diode by way of a resistor, and an automatic gain control voltage is derived from the other electrode of the diode. A blocking circuit is provided to prevent conduction of the diode during the line synchronizing signal. A video output circuit capacitively coupled to the input circuit is clamped by a line flyback pulses which are also blocked during the line synchronizing period.
Inventors
- 👤 Marcel Rognon
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 15:19
CPC Classifications
H; H04; H04N; H04N5/00; H04N5/14; H04N5/16; H04N5/18; H04N5/185; H04N5/44; H04N5/52; H04N5/53
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
129 words
An automatic gain control circuit for a television receiver that receives television signals, comprising means for receiving video signals from said television signals; a gate circuit having a first input coupled to said receiving means, a second blocking input and an output; means for generating an automatic gain control signal coupled to the output of said gate circuit; a source of line flyback signals; means for blocking said gate comprising a transistor having at least base and collector electrodes, said collector being coupled to said flyback signal source and being coupled to said blocking input and means for preventing the operation of said generating means during the occurrence of synchronization pulses comprising means for deriving a synchronization signal from said television signal coupled to said base of said transitor.
Claim 2
Dependent Claim
129 words
An automatic gain control circuit for a television receiver that receives television signals, comprising means for receiving video signals from said television signals; a gate circuit having a first input coupled to said receiving means, a second blocking input and an output; means for generating an automatic gain control signal coupled to the output of said gate circuit; a source of line flyback signals; means for blocking said gate comprising a transistor having at least base and collector electrodes, said collector being coupled to said flyback signal source and being coupled to said blocking input and means for preventing the operation of said generating means during the occurrence of synchronization pulses comprising means for deriving a synchronization signal from said television signal coupled to said base of said transitor.
Claim 3
Dependent Claim
20 words
A circuit as claimed in claim 1 further comprising a differentiating network coupled between said blocking input and said transistor.
Claim 4
Dependent Claim
33 words
A circuit as claimed in claim 1 wherein said gate circuit further comprises a diode having a cathode coupled to said first gate input and an anode coupled to said second blocking input.
Claim 5
Dependent Claim
28 words
A circuit as claimed in claim 1 further comprising a clamping circuit coupled to said blocking means, and means for adjusting the clamping level of said clamping means.
Claim 6
Dependent Claim
21 words
A circuit as claimed in claim 4 further comprising a differentiating network coupled between said clamping circuit and said blocking means.
Claim 7
Dependent Claim
14 words
A circuit as claimed in claim 4 wherein said adjusting means comprises a potentiometer.
Claim 8
Dependent Claim
48 words
A circuit as claimed in claim 6 wherein said clamping circuit comprises a series cirCuit including a capacitor and oppositely poled diodes, the junction of one of said diodes and said capacitor being coupled to said potentiometer, the junction of said diodes being coupled to said blocking means.
Claim 9
Dependent Claim
52 words
A circuit as claimed in claim 6 wherein said clamping means comprises a second transistor having emitter, base, and collector electrodes, and a capacitor coupled in series with said emitter-collector path of said second transistor, one of said electrodes being coupled to said potentiometer, the base being coupled to said blocking means.
References Cited (Backward Citations)
US3288926A
Cited
US3305637A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-02-22 | 1974-08-24 | 1975-02-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-02-22 | 1978-08-24 | 1979-02-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-02-22 | 1982-08-24 | 1983-02-23 | $7700.00 | Window Closed / Lapsed |