Automatic chroma control circuits

Claim 2

In a color television receiver of the type employing a circuit for responding to and selecting from a composite television signal an oscillatory burst signal representative of a chroma subcarrier signal and transmitted with said composite signal during a color television transmission, in combination therewith comprising: a. A filter network having a relatively narrow frequency response characteristic permitting propagation therethrough of signal frequencies including noise components about said chroma subcarrier frequency, said filter network having an input terminal coupled to said circuit, and an output terminal for providing thereat a filtered signal; b. an oscillator circuit, including said filter network disposed in an AC feedback path of said oscillator for determining the frequency of oscillations, said oscillator providing an output signal whose magnitude varies in accordance with said magnitude of said filtered frequency signal components, c. detector circuit means having an input responsive to said varying magnitude oscillator signal for providing at an output thereof a control voltage in accordance with the peak amplitude of said oscillator signal, including any such peaks as produced by said noise components, d. a gain controllable amplifier responsive to said composite signal for providing at an output thereof a predetermined band of frequency components, including said oscillatory burst frequency signal, determinative of color information present in said composite signal, and e. means coupling said detector circuit means to said amplifier for controlling the gain thereof in accordance with the magnitude of said control voltage.

Claim 3

The color television receiver according to claim 1 wherein said filter network comprises, a. a crystal having a center frequency in the vicinity of said chrominance subcarrier frequency and, b. a variable capacitor in series with said crystal for adjusting the exact center frequency of said filter about said chrominance subcarrier frequency, whereby said frequency as adjusted determines the frequency of said oscillations.

Claim 4

a first off-chip, tuned circuit having a first given band-pass characteristic within said range of said chrominance information signal components, coupled to said first chip terminal, for providing chrominance selectivity for said first chroma stage,

Claim 5

a first off-chip, tuned circuit having a first given band-pass characteristic within said range of said chrominance information signal components, coupled to said first chip terminal, for providing chrominance selectivity for said first chroma stage,

Claim 6

a second off-chip tuned circuit having a second given band-pass characteristic within said range coupled to said second chip terminal for providing chrominance selectivity for said third chroma stage,

Claim 7

a second off-chip tuned circuit having a second given band-pass characteristic within said range coupled to said second chip terminal for providing chrominance selectivity for said third chroma stage,

Claim 8

Automatic chroma control apparatus for a television receiver comprising, a. a gain controllable amplifier responsive to chrominance frequency signal components transmitted with a composite television signal, to provide at an output thereof a predetermined band of chrominance frequency components, including an oscillatory burst frequency signal transmitted with said composite signal, determinative of color informations, b. first means responsive to said composite signal for selectively providing at an output thereof an amplified version of said oscillatory burst signal, c. an oscillator circuit, including a crystal filter coupled between an input and output terminal thereof, for providing AC feedback to said oscillator for determining the frequency of oscillations, said input terminal coupled to said first means for applying to said oscillator said oscillatory burst signal and any other signal frequencies including noise components, within the band-pass determined by said crystal, for locking said oscillator in phase and frequency to said burst signal, said oscillator providing an output signal whose magnitude varies in accordance with said magnitude of said crystal filtered frequency signal components, d. detector circuit means having an input responsive to said varying magnitude oscillator signal for providing at an output thereof a control voltage in accordance with the peak amplitude of said oscillator signal, including any such peaks as produced by said noise components, e. means coupling said detector circuit means to said amplifier for controlling the gain thereof in accordance with the magnitude of said control voltage.

Claim 9

Automatic chroma control apparatus for a television receiver comprising, a. a gain controllable amplifier responsive to chrominance frequency signal components transmitted with a composite television signal, to provide at an output thereof a predetermined band of chrominance frequency components, including an oscillatory burst frequency signal transmitted with said composite signal, determinative of color informations, b. first means responsive to said composite signal for selectively providing at an output thereof an amplified version of said oscillatory burst signal, c. an oscillator circuit, including a crystal filter coupled between an input and output terminal thereof, for providing AC feedback to said oscillator for determining the frequency of oscillations, said input terminal coupled to said first means for applying to said oscillator said oscillatory burst signal and any other signal frequencies including noise components, within the band-pass determined by said crystal, for locking said oscillator in phase and frequency to said burst signal, said oscillator providing an output signal whose magnitude varies in accordance with said magnitude of said crystal filtered frequency signal components, d. detector circuit means having an input responsive to said varying magnitude oscillator signal for providing at an output thereof a control voltage in accordance with the peak amplitude of said oscillator signal, including any such peaks as produced by said noise components, e. means coupling said detector circuit means to said amplifier for controlling the gain thereof in accordance with the magnitude of said control voltage.

Claim 10

a third off-chip, tuned circuit having a third given band-pass characteristic, relatively wider than said first and second band-pass characteristic within said range and coupled to said third one of said chip terminals for providing selectivity for said burst amplifier,

Claim 11

a third off-chip, tuned circuit having a third given band-pass characteristic, relatively wider than said first and second band-pass characteristic within said range and coupled to said third one of said chip terminals for providing selectivity for said burst amplifier,

Claim 12

The automatic control apparatus according to claim 3 wherein said detector circuit means, comprises, a. a transistor having a base, collector and emitter electrode, b. means for applying said output signal of said oscillator to said base electrode, c. a capacitor and a resistor coupling said emitter electrode to a point of reference potential, and selected to provide an RC time constant for operating with said base to emitter junction of said transistor at said oscillator frequency in a peak detecting circuit, and d. means coupled to said collector electrode for applying a source of operating potential thereto.

Claim 13

an off-chip filter network, comprising a crystal in series with a variable capacitor, coupled between said third and said fourth terminals for sustaining oscillations in said oscillator circuit while providing a narrow band-pass to said burst signal as selectively amplified by said burst amplifier, said feedback voltage due to said filter network being relatively small compared to the magnitude of said burst signal applied thereto, to cause said oscillator to vary in amplitude in accordance with signals at said third terminal within the band-pass of said crystal,

Claim 14

an off-chip filter network, comprising a crystal in series with a variable capacitor, coupled between said third and said fourth terminals for sustaining oscillations in said oscillator circuit while providing a narrow band-pass to said burst signal as selectively amplified by said burst amplifier, said feedback voltage due to said filter network being relatively small compared to the magnitude of said burst signal applied thereto, to cause said oscillator to vary in amplitude in accordance with signals at said third terminal within the band-pass of said crystal,

Claim 15

Chroma processing circuitry for use in a color television receiver for responding to chrominance information signal components contained in a composite video signal provided by said receiver during a color transmission, comprising, a. a gain-controllable chroma amplifier, including a first resonant circuit, of a first band-pass characteristic to permit selective amplification of said chrominance information signal components, when said composite signal if applied to said amplifier, b. gain determining biasing means coupled to said amplifier for providing a reference biasing level thereto, determining a first gain condition of said amplifier, c. a burst amplifier including a second resonant circuit having a second band-pass characteristic, coupled to said gain controllable chroma amplifier for providing at an output an oscillatory burst signal contained in said chrominance information signals during a color transmission, d. an oscillator having an output terminal coupled to said burst amplifier and an input terminal, e. a narrow band crystal filter coupled between the output and input terminal of said oscillator for providing a given amplitude AC feedback signal for said oscillator sufficient to sustain oscillations, while permitting said burst amplifier output signal as developed at said output terminal to couple to said input terminal to lock said oscillator and vary the oscillator signal amplitude in accordance with the signals coupling through said crystal filter, f. a peak detector, including a resistor, capacitor time constant network, having an input responsive to said varying amplitude oscillator signal, for providing at an output terminal a control voltage proportional to the highest peak value of said oscillator signal, g. means coupling said output terminal of said peak detector to said gain determining baising means for varying said reference biasing level and therefore said chroma amplifier gain in accordance with said amplitude variation of said oscillator Signal.

Claim 16

Chroma processing circuitry for use in a color television receiver for responding to chrominance information signal components contained in a composite video signal provided by said receiver during a color transmission, comprising, a. a gain-controllable chroma amplifier, including a first resonant circuit, of a first band-pass characteristic to permit selective amplification of said chrominance information signal components, when said composite signal if applied to said amplifier, b. gain determining biasing means coupled to said amplifier for providing a reference biasing level thereto, determining a first gain condition of said amplifier, c. a burst amplifier including a second resonant circuit having a second band-pass characteristic, coupled to said gain controllable chroma amplifier for providing at an output an oscillatory burst signal contained in said chrominance information signals during a color transmission, d. an oscillator having an output terminal coupled to said burst amplifier and an input terminal, e. a narrow band crystal filter coupled between the output and input terminal of said oscillator for providing a given amplitude AC feedback signal for said oscillator sufficient to sustain oscillations, while permitting said burst amplifier output signal as developed at said output terminal to couple to said input terminal to lock said oscillator and vary the oscillator signal amplitude in accordance with the signals coupling through said crystal filter, f. a peak detector, including a resistor, capacitor time constant network, having an input responsive to said varying amplitude oscillator signal, for providing at an output terminal a control voltage proportional to the highest peak value of said oscillator signal, g. means coupling said output terminal of said peak detector to said gain determining baising means for varying said reference biasing level and therefore said chroma amplifier gain in accordance with said amplitude variation of said oscillator Signal.

Claim 17

Chroma processing circuitry for use in a color television receiver, for responding to chrominance information signal components transmitted with a composite signal during a color transmission, comprising,

Claim 18

Chroma processing circuitry for use in a color television receiver, for responding to chrominance information signal components transmitted with a composite signal during a color transmission, comprising,

Claim 19

an off-chip time constant network comprising a capacitor in shunt with a resistor coupled to said fifth one of said chip terminals to operate said peak detector at said chrominance subcarrier frequency, to develop a voltage across said capacitor in accordance with said varying amplitude oscillator signal.

Claim 20

an off-chip time constant network comprising a capacitor in shunt with a resistor coupled to said fifth one of said chip terminals to operate said peak detector at said chrominance subcarrier frequency, to develop a voltage across said capacitor in accordance with said varying amplitude oscillator signal.

Claim 21

The chroma processing circuitry according to claim 6 wherein a direct coupling path between said first chroma stage and said second chroma stage comprises, a. an avalanche diode mounted on said chip and coupled between said first output terminal, coupled to said first off-chip tuned circuit, and an on-chip input terminal of said second chroma amplifying stage.

Claim 22

Automatic chroma control circuitry for use in a color television receiver, capable of responding to and processing a transmitted signal having color information components contained therein for providing therefrom a composite video signal including said color information components and an oscillatory burst signal together with undesired noise components of a random nature, comprising, a. a filter network having a relatively narrow frequency response characteristic sufficient to permit pRopagation therethrough of signal frequencies including said noise components about a predetermined color subcarrier frequency, said filter having an input terminal responsive to said composite video signal, and an output terminal for providing narrow band color information frequency signals consisting of the oscillatory burst signal and the undesired noise components. b. oscillator circuit means including said filter network coupled between an input and output terminal for providing AC feedback to said oscillator means for determining the frequency of oscillations, said oscillator providing an output signal whose magnitude varies in accordance with the magnitude of said filtered frequency signal components as permitted to propagate through said filter network including said noise components, c. a peak detector circuit having an input responsive to said varying magnitude oscillator signal for providing at an output thereof a control voltage in accordance with the peak amplitude of said oscillator signal which may include any such peaks as produced by said noise components, d. a gain controllable amplifier responsive to said composite signal for providing at an output thereof a predetermined band of frequency components determinative of said color information present in said composite signal, and e. means coupling said detector circuit to said amplifier for controlling the gain thereof in accordance with the magnitude of said control voltage according to said varying amplitude oscillator signal whereby the gain as controlled may be substantially equal for low amplitude color information signals and high amplitude noise components, as that gain for low amplitude noise components and high amplitude color information signals.

Claim 23

Automatic chroma control circuitry for use in a color television receiver, capable of responding to and processing a transmitted signal having color information components contained therein for providing therefrom a composite video signal including said color information components and an oscillatory burst signal together with undesired noise components of a random nature, comprising, a. a filter network having a relatively narrow frequency response characteristic sufficient to permit pRopagation therethrough of signal frequencies including said noise components about a predetermined color subcarrier frequency, said filter having an input terminal responsive to said composite video signal, and an output terminal for providing narrow band color information frequency signals consisting of the oscillatory burst signal and the undesired noise components. b. oscillator circuit means including said filter network coupled between an input and output terminal for providing AC feedback to said oscillator means for determining the frequency of oscillations, said oscillator providing an output signal whose magnitude varies in accordance with the magnitude of said filtered frequency signal components as permitted to propagate through said filter network including said noise components, c. a peak detector circuit having an input responsive to said varying magnitude oscillator signal for providing at an output thereof a control voltage in accordance with the peak amplitude of said oscillator signal which may include any such peaks as produced by said noise components, d. a gain controllable amplifier responsive to said composite signal for providing at an output thereof a predetermined band of frequency components determinative of said color information present in said composite signal, and e. means coupling said detector circuit to said amplifier for controlling the gain thereof in accordance with the magnitude of said control voltage according to said varying amplitude oscillator signal whereby the gain as controlled may be substantially equal for low amplitude color information signals and high amplitude noise components, as that gain for low amplitude noise components and high amplitude color information signals.

Claim 24

The automatic chroma control circuitry according to claim 8 further comprising, a. means coupled to said oscillator circuit for varying the quiescent peak-to-peak voltage swing of said output signal, to provide a reference level for said peak detector circuit.

Claim 25

Chroma processing circuitry for use in a color television receiver for responding to chrominance information signal components contained in a composite video signal provided by said receiver during a color transmission, comprising, a. an integrated circuit totem pole amplifier including first and second monolithic transistors deposited on a substrate, each having a base, collector and emitter electrode, said collector electrode of said first transistor coupled to said emitter electrode of said second transistor, said collector electrode of said second transistor coupled to a first terminal on said substrate, and said base electrode of said first transistor coupled to a second terminal on said substrate, for application of a video signal to said second terminal, b. an off-substrate parallel resonant circuit having a first band-pass characteristic within said chrominance information range coupled to said first terminal on said substrate for providing chrominance selectivity for said totem pole amplifier, c. an integrated circuit biasing network including a third monolithic follower transistor configuration mounted on said substrate and having a base electrode, including means coupled thereto for operating said follower stage at a voltage reference level, said emitter electrode of said monolithic follower transistor being resistively coupled to said base electrode of said second transistor for supplying an operating bias current thereto, d. a burst amplifier including a fourth monolithic transistor mounted on said substrate having a base electrode coupled to said collector electrode of said second transistor for applying said chrominance information components thereto, and a collector electrode coupled to a third terminal on said substrate, e. a second off-substrate parallel resonant circuit having a wider band-pass characteristic than said first within said range coupled to said third terminal for providing selectively for said bursT amplifier about said chrominance subcarrier frequency, f. oscillator circuit means, included on said substrate, having an output terminal coupled to said third terminal and an input terminal coupled to a fourth terminal on said substrate, g. an off-substrate narrow band filter network, including, a crystal coupled between said third and fourth terminals for providing a given amplitude AC feedback signal for said oscillator circuit means, sufficient to sustain oscillations, while permitting said burst amplifier output signal as developed at said third terminal to vary the oscillator signal amplitude in accordance with the signal applied through said crystal to said oscillator input terminal, h. a fifth monolithic transistor arranged in a follower configuration and having a base electrode directly connected to an on-substrate terminal of said oscillator, and having an emitter electrode coupled to a fifth terminal on said substrate, i. an off-substrate RC network coupled to said fifth terminal, having a time constant associated therewith to operate said base to emitter junction of said fifth monolithic transistor in a peak detector circuit, to cause said capacitor to charge to a peak voltage value of a magnitude in accordance with said varying oscillator amplitude, and j. means including a sixth monolithic transistor, on said substrate having a base electrode coupled to said fifth terminal and a collector electrode coupled between said base electrode of said second transistor and said resistively coupled emitter electrode of said third monolithic follower transistor to bypass a portion of said base operating biasing current as supplied to said second transistor in accordance with said peak voltage value developed across said capacitor.

Claim 26

Chroma processing circuitry for use in a color television receiver for responding to chrominance information signal components contained in a composite video signal provided by said receiver during a color transmission, comprising, a. an integrated circuit totem pole amplifier including first and second monolithic transistors deposited on a substrate, each having a base, collector and emitter electrode, said collector electrode of said first transistor coupled to said emitter electrode of said second transistor, said collector electrode of said second transistor coupled to a first terminal on said substrate, and said base electrode of said first transistor coupled to a second terminal on said substrate, for application of a video signal to said second terminal, b. an off-substrate parallel resonant circuit having a first band-pass characteristic within said chrominance information range coupled to said first terminal on said substrate for providing chrominance selectivity for said totem pole amplifier, c. an integrated circuit biasing network including a third monolithic follower transistor configuration mounted on said substrate and having a base electrode, including means coupled thereto for operating said follower stage at a voltage reference level, said emitter electrode of said monolithic follower transistor being resistively coupled to said base electrode of said second transistor for supplying an operating bias current thereto, d. a burst amplifier including a fourth monolithic transistor mounted on said substrate having a base electrode coupled to said collector electrode of said second transistor for applying said chrominance information components thereto, and a collector electrode coupled to a third terminal on said substrate, e. a second off-substrate parallel resonant circuit having a wider band-pass characteristic than said first within said range coupled to said third terminal for providing selectively for said bursT amplifier about said chrominance subcarrier frequency, f. oscillator circuit means, included on said substrate, having an output terminal coupled to said third terminal and an input terminal coupled to a fourth terminal on said substrate, g. an off-substrate narrow band filter network, including, a crystal coupled between said third and fourth terminals for providing a given amplitude AC feedback signal for said oscillator circuit means, sufficient to sustain oscillations, while permitting said burst amplifier output signal as developed at said third terminal to vary the oscillator signal amplitude in accordance with the signal applied through said crystal to said oscillator input terminal, h. a fifth monolithic transistor arranged in a follower configuration and having a base electrode directly connected to an on-substrate terminal of said oscillator, and having an emitter electrode coupled to a fifth terminal on said substrate, i. an off-substrate RC network coupled to said fifth terminal, having a time constant associated therewith to operate said base to emitter junction of said fifth monolithic transistor in a peak detector circuit, to cause said capacitor to charge to a peak voltage value of a magnitude in accordance with said varying oscillator amplitude, and j. means including a sixth monolithic transistor, on said substrate having a base electrode coupled to said fifth terminal and a collector electrode coupled between said base electrode of said second transistor and said resistively coupled emitter electrode of said third monolithic follower transistor to bypass a portion of said base operating biasing current as supplied to said second transistor in accordance with said peak voltage value developed across said capacitor.