US3877067A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Peak chroma control circuit
Assignee: Thomas International Corp
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Filing: 1973-03-26
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Granted: 1975-04-08
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Expires: 1993-03-26
Abstract
Abstract An Automatic Chroma Control Circuit for a color television receiver includes an integrated circuit chroma amplifier having a gain controlled by a DC voltage at a bias input. The output of the chroma amplifier is coupled through a chroma bandpass filter to the base of a transistor. A diode-resistor biasing network drives the transistor conductive in proportion to positive peaks of the chroma signal. A capacitor means in shunt with the transistor develops a proportional DC voltage. A switch selectively connects the transistor chroma control to the bias input and in shunt with a manual chroma control potentiometer, restricting the range of the manual chroma control.
Inventors
- 👤 John H Furrey
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 21:54
CPC Classifications
H; H04; H04N; H04N9/00; H04N9/64; H04N9/68
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
247 words
In a color television receiver having a chroma channel for processing a chroma video component of a composite color television signal, the chroma channel having a bias input for controlling the gain of the chroma channel in proportion to a DC voltage at the bias input, an automatic chroma control circuit for generating the DC voltage to control the gain of the chroma channel, comprising: a controllable semiconductor device having at least a control electrode and an output electrode; peak circuit means for directly driving the control electrode of the semiconductor device by peaks of the chroma video component from the output of the chroma channel to develop in the output electrode a current proportional to the peaks of the chroma video component; integrating means coupled to the output electrode for developing said DC voltage with a magnitude proportional to the peaks of the chroma video component; a manual chroma control means connected at all times to the bias input for developing an adjustable DC voltage having a magnitude proportional to a desired gain for the chroma channel; and means including a switch actuable for selectively coupling said integrating means and said controllable semiconductor device in shunt across said manual chroma control to form a shunt regulator means which decreases the range of the adjustable DC voltage developed by the manual chroma control while the switch is actuated, whereby deactuation of the switch increases the range of the adjustable DC voltage developed by the manual chroma control.
Claim 2
Dependent Claim
247 words
In a color television receiver having a chroma channel for processing a chroma video component of a composite color television signal, the chroma channel having a bias input for controlling the gain of the chroma channel in proportion to a DC voltage at the bias input, an automatic chroma control circuit for generating the DC voltage to control the gain of the chroma channel, comprising: a controllable semiconductor device having at least a control electrode and an output electrode; peak circuit means for directly driving the control electrode of the semiconductor device by peaks of the chroma video component from the output of the chroma channel to develop in the output electrode a current proportional to the peaks of the chroma video component; integrating means coupled to the output electrode for developing said DC voltage with a magnitude proportional to the peaks of the chroma video component; a manual chroma control means connected at all times to the bias input for developing an adjustable DC voltage having a magnitude proportional to a desired gain for the chroma channel; and means including a switch actuable for selectively coupling said integrating means and said controllable semiconductor device in shunt across said manual chroma control to form a shunt regulator means which decreases the range of the adjustable DC voltage developed by the manual chroma control while the switch is actuated, whereby deactuation of the switch increases the range of the adjustable DC voltage developed by the manual chroma control.
Claim 3
Dependent Claim
47 words
The automatic chroma control circuit of claim 1 wherein the peak circuit means includes a source of supply potential, diode means, and resistive means connecting said diode means between the supply potential and one of the electrodes of the semiconductor device to establish a peak set-up voltage.
Claim 4
Dependent Claim
22 words
The automatic chroma control circuit of claim 2 wherein said resistive means includes a variable resistor which forms a peak set-up control.
Claim 5
Dependent Claim
38 words
The automatic chroma control circuit of claim 1 wherein said peak circuit means includes chroma bandpass filter means coupled between the output of the chroma channel and the control electrode, said filter including at least one series capacitor.
Claim 6
Dependent Claim
159 words
In a color television receiveer having a chroma channel for processing a chroma video component of a composite color television signal to produce at an output an AC chroma signal having positive and negative excursions, an automatic chroma control circuit for generating a control voltage to control the gain of the chroma channel, comprising: a controllable semiconductor device having at least a control electrode and an output electrode; peak circuit means for directly driving the control electrode of the semiconductor device by peaks of only one of the excursions of the AC chroma signal from the output of the chroma channel to develop in the output electrode a current proportional to the peaks of the chroma video component, including a biasing network having a plurality of resistors and a diode coupled between said resistors and said control electrode for conducting on one of the excursions of the AC chroma signal to provide DC restoration for the AC chroma signal;
Claim 7
Dependent Claim
159 words
In a color television receiveer having a chroma channel for processing a chroma video component of a composite color television signal to produce at an output an AC chroma signal having positive and negative excursions, an automatic chroma control circuit for generating a control voltage to control the gain of the chroma channel, comprising: a controllable semiconductor device having at least a control electrode and an output electrode; peak circuit means for directly driving the control electrode of the semiconductor device by peaks of only one of the excursions of the AC chroma signal from the output of the chroma channel to develop in the output electrode a current proportional to the peaks of the chroma video component, including a biasing network having a plurality of resistors and a diode coupled between said resistors and said control electrode for conducting on one of the excursions of the AC chroma signal to provide DC restoration for the AC chroma signal;
Claim 8
Dependent Claim
33 words
The automatic chroma control circuit of claim 5 wherein said integrating means comprises capacitor means to integrate the current flow in the controllable semiconductor device in order to develop said DC control voltage.
References Cited (Backward Citations)
US3740462A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-04-07 | 1978-10-07 | 1979-04-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-04-07 | 1982-10-07 | 1983-04-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-04-07 | 1986-10-07 | 1987-04-08 | $7700.00 | Window Closed / Lapsed |