US3571499A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Automatic saturation control for a color television receiver
Assignee: Motorola Solutions Inc
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Filing: 1969-04-01
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Granted: 1971-03-16
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Expires: 1989-04-01
Abstract
Abstract A color television receiver using direct demodulation of the color and brightness signals is provided with an automatic chroma control circuit for controlling the gain of the color IF amplifier stage in order to prevent the saturation of the demodulated color signals from exceeding the peak brightness signals. The output of the video amplifier is supplied through a peak detector to one input of a differential amplifier, the other input to which is obtained through a second peak detector from the outputs of the color demodulators. The output of the differential amplifier is used to control a switching transistor, which supplies D.C. control signals to the color IF amplifier to control the bias on the final stage thereof. A pair of comparison circuits of the same type are provided, with the second circuit being responsive to the peak blackness signals and the saturation of the color components occurring during the black-going portions of the video signals, while the first comparison circuit compares the white-going peak portions of the video signal with the saturated color appearing during the white-going portions. The blanking circuit operates to disable the comparison circuits during the blanking intervals, so that the automatic chroma control circuit is responsive only to the video signals present during the trace portion of the video signal.
Inventors
- 👤 Robert B Hansen
- 👤 William H Slavik
- 👤 Arthur F Seymour
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 14:44
CPC Classifications
H; H04; H04N; H04N9/00; H04N9/64; H04N9/68
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
161 words
In a color television receiver for a composite signal comprising brightness signal components of a television image and a subcarrier signal phase-modulated by color difference signals to represent hue and amplitude-modulated to represent saturation, said receiver having a brightness signal component processing channel and a color signAl component processing channel including a demodulator for obtaining at least one signal representing one hue, an automatic saturation control circuit including in combination: first means for obtaining a signal representative of the peak brightness of the brightness signal components; second means for obtaining a signal representative of the peak saturation of at least one phase of the demodulated color signal; means for comparing the outputs of the first and second means for providing a control signal indicative of the relative amplitudes of the output signals from the first and second means; and control means for applying the control signal obtained from the comparing means to the color processing channel for controlling the operation thereof.
Claim 2
Dependent Claim
161 words
In a color television receiver for a composite signal comprising brightness signal components of a television image and a subcarrier signal phase-modulated by color difference signals to represent hue and amplitude-modulated to represent saturation, said receiver having a brightness signal component processing channel and a color signAl component processing channel including a demodulator for obtaining at least one signal representing one hue, an automatic saturation control circuit including in combination: first means for obtaining a signal representative of the peak brightness of the brightness signal components; second means for obtaining a signal representative of the peak saturation of at least one phase of the demodulated color signal; means for comparing the outputs of the first and second means for providing a control signal indicative of the relative amplitudes of the output signals from the first and second means; and control means for applying the control signal obtained from the comparing means to the color processing channel for controlling the operation thereof.
Claim 3
Dependent Claim
49 words
The combination according to claim 1 wherein the comparing means is a differential amplifier having a pair of inputs, with the output of the first means being applied to one of the inputs and with the output of the second means being applied to the other of the inputs.
Claim 4
Dependent Claim
20 words
The combination according to claim 1 wherein the first and second means each include peak detectors having integrating circuits therein.
Claim 5
Dependent Claim
42 words
The combination according to claim 1 wherein the color processing channel of the television receiver includes an IF amplifier stage and where the control signal is applied to the IF amplifier stage to vary the operating bias for the color IF amplifier.
Claim 6
Dependent Claim
66 words
The combination according to claim 4 wherein the control means includes an additional integrating circuit and wherein the comparing means is a differential amplifier providing a first output whenever the magnitude of the brightness signal components exceeds the magnitude of the demodulated color signal and for providing a second output whenever the magnitude of the demodulated color signal exceeds the magnitude of the brightness signal components.
Claim 7
Dependent Claim
93 words
The combination according to claim 1 further including first and second inverter circuits, a second comparing means connected to the outputs of the first and second signal obtaining means through the first and second inverter circuits, respectively, for providing a second control signal indicative of the relative amplitudes of the inverted output signals from the first and second means, said first and second comparing means being similar, and a second control means for applying the control signal obtained from the second comparing means to the color processing channel for controlling the operation thereof.
Claim 8
Dependent Claim
28 words
The combination according to claim 6 wherein the control means each include an integrating circuit for providing respective control signals representative of the outputs of the comparing means.
Claim 9
Dependent Claim
141 words
The combination according to claim 7 wherein the comparing means each are differential amplifiers, each having a pair of inputs to which the outputs of the first and second means are applied and each providing a first outputs signal whenever the amplitude of the applied output of the first means exceeds the amplitude of the applied output of the second means, and each providing a second output signal whenever the amplitude of the applied output of the second means exceeds the amplitude of the applied output of the first means, and further including switching means, in each of said control means, with the output of the switching means being controlled by the control signal obtained from the respective differential amplifier and being applied through the integrating circuits in said control means to the color processing channel for controlling the operation thereof.
Claim 10
Dependent Claim
63 words
The combination according to claim 8 wherein each of the switching means is rendered conductive whenever the second output is obtained from the corresponding differential amplifier and is rendered nonconductive whenever the first output is obtained from the corresponding differential amplifier to thereby vary the signal level applied through the integrating circuits to the color processing channel to vary the gain thereof accordIngly.
Claim 11
Dependent Claim
25 words
The combination according to claim 9 wherein the outputs of the first and second comparing means both are combined for controlling the color processing channel.
Claim 12
Dependent Claim
215 words
In a color television receiver for a composite television signal comprising brightness signal components of a television image and a subcarrier signal modulated by color difference signals representing hue and saturation of the image at different phases of the subcarrier, said receiver having a brightness signal processing channel including a video amplifier and a color signal processing channel including a color IF amplifier, said receiver further including at least one demodulator circuit for demodulating the subcarrier signal of one phase to develop a signal representative of the saturation of one hue, an automatic color control circuit including in combination: a first peak detecting circuit connected to the output of the video amplifier for providing an output signal representative of the peak amplitude of the brightness signal components; a second peak detector connected to the output of the demodulator for providing an output signal representative of the peak saturation of said one hue; a differential amplifier circuit having first and second inputs, with the output of the first peak detector being connected to one of the inputs and with output of the second peak detector being connected to the other of the inputs; and means responsive to the output of the differential amplifier for controlling the gain of the IF amplifier in the color processing channel.
Claim 13
Dependent Claim
215 words
In a color television receiver for a composite television signal comprising brightness signal components of a television image and a subcarrier signal modulated by color difference signals representing hue and saturation of the image at different phases of the subcarrier, said receiver having a brightness signal processing channel including a video amplifier and a color signal processing channel including a color IF amplifier, said receiver further including at least one demodulator circuit for demodulating the subcarrier signal of one phase to develop a signal representative of the saturation of one hue, an automatic color control circuit including in combination: a first peak detecting circuit connected to the output of the video amplifier for providing an output signal representative of the peak amplitude of the brightness signal components; a second peak detector connected to the output of the demodulator for providing an output signal representative of the peak saturation of said one hue; a differential amplifier circuit having first and second inputs, with the output of the first peak detector being connected to one of the inputs and with output of the second peak detector being connected to the other of the inputs; and means responsive to the output of the differential amplifier for controlling the gain of the IF amplifier in the color processing channel.
Claim 14
Dependent Claim
32 words
The combination according to claim 11 wherein the peak detectors each include an integrating circuit having a long time constant, said time constant extending over several frames of a received television signal.
Claim 15
Dependent Claim
59 words
The combination according to claim 11 wherein the received signal has trace and retrace intervals and wherein the television receiver further includes a blanking circuit for blanking the cathode ray tube during retrace intervals of the received television signal, further including means responsive to the blanking circuit for disabling erroneous operation of the differential amplifier during the blanking intervals.
Claim 16
Dependent Claim
54 words
The combination according to claim 11 wherein said color television receiver includes a plurality of demodulator circuits for demodulating each of a plurality of different phases of the subcarrier signal, further including OR gate circuits responsive to the outputs of all of said demodulators for providing the input signal to the second peak detector.
References Cited (Backward Citations)
US3267210A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-03-15 | 1974-09-14 | 1975-03-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-03-15 | 1978-09-14 | 1979-03-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-03-15 | 1982-09-14 | 1983-03-16 | $7700.00 | Window Closed / Lapsed |