US3852807A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Automatic hue control circuit
Assignee: Motorola Solutions Inc
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Filing: 1973-09-24
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Granted: 1974-12-03
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Expires: 1993-09-24
Abstract
Abstract An automatic hue control circuit for a color television receiver operates to improve the flesh tones reproduced by the receiver by causing signals lying near the +I axis to be shifted to the +I axis if they fall within a predetermined angle on either side of the +I axis. This is accomplished with little or no effect on hues lying outside of the angle about the +I axis in which the correction occurs, so that correction is confined to the area about the +I axis where it is desired. This is accomplished by splitting the chroma signal into its I and Q constituent parts either at base-band or subcarrier frequencies and comparing the value of a predetermined fraction of +I components with the absolute value of Q voltage components EQ to control the operation of a gating circuit to prevent the passage of Q signals if the value of the +I component is greater than EQ and to permit the passage of signal components if EQ is greater than the fractional value of the +I components. The output of this gate then is combined with the I signal components to provide a reconstituted or reconstructed color signal which then is used to form the red, blue and green signals necessary to drive the cathode ray tube. The Q signal components are blocked only for signals within the angle determined by the fraction of the +I component which is compared with EQ . For signals lying outside of this angle, no modification of the color signals takes place.
Inventors
- 👤 G Caprio
- 👤 N Parker
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 06:58
CPC Classifications
H; H04; H04N; H04N9/00; H04N9/64; H04N9/643
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
375 words
In a color television receiver for receiving a composite signal comprising at least brightness signal components, a subcarrier signal component modulated in phase and amplitude to represent hue and saturation of a color image, and a burst component for phase locking the signal of an oscillator of the receiver to control color signal demodulators for the subscriber at different phases of the oscillator output signal, an automatic hue control circuit for controlling hue variations about a predetermined phase of said subcarrier signal component relative to the output signal of the oscillator, said automatic hue control circuit including in combination: first circuit means responsive to at least the subcarrier component of said composite signal for providing a first demodulated signal at said predetermined phase and having a magnitude corresponding to the magnitude of signals at said predetermined phase; second circuit means responsive to at least the subcarrier component of said composite signal for producing a first control voltage representative of the absolute magnitude of signals in quadrature with signals at said predetermined phase; means for supplying said composite signal to said first and second circuit means; comparator circuit means having first and second inputs and an output; first coupling means connecting said second circuit means with said first input of said comparator circuit means for applying said first control voltage thereto; second coupling means connecting said first circuit means with the second input of said comparator circuit means for applying a second control voltage thereto, said second control voltage having a magnitude which has a predetermined value relative to the magnitude of said first demodulated signal; gating circuit means having a signal input, an output, and a control input and operative to pass signals from the input to the output thereof in response to the application of an enabling signal on the control input thereof; means for applying said quadrature signals to the input of said gating circuit means; means coupling the output of said comparator circuit means to the control input of said gating circuit means to apply an enabling signal thereto whenever said first control voltage is greater than said second control voltage; and means for utilizing the output of said gating circuit means to produce color signals for reproduction by said television receiver.
Claim 2
Dependent Claim
375 words
In a color television receiver for receiving a composite signal comprising at least brightness signal components, a subcarrier signal component modulated in phase and amplitude to represent hue and saturation of a color image, and a burst component for phase locking the signal of an oscillator of the receiver to control color signal demodulators for the subscriber at different phases of the oscillator output signal, an automatic hue control circuit for controlling hue variations about a predetermined phase of said subcarrier signal component relative to the output signal of the oscillator, said automatic hue control circuit including in combination: first circuit means responsive to at least the subcarrier component of said composite signal for providing a first demodulated signal at said predetermined phase and having a magnitude corresponding to the magnitude of signals at said predetermined phase; second circuit means responsive to at least the subcarrier component of said composite signal for producing a first control voltage representative of the absolute magnitude of signals in quadrature with signals at said predetermined phase; means for supplying said composite signal to said first and second circuit means; comparator circuit means having first and second inputs and an output; first coupling means connecting said second circuit means with said first input of said comparator circuit means for applying said first control voltage thereto; second coupling means connecting said first circuit means with the second input of said comparator circuit means for applying a second control voltage thereto, said second control voltage having a magnitude which has a predetermined value relative to the magnitude of said first demodulated signal; gating circuit means having a signal input, an output, and a control input and operative to pass signals from the input to the output thereof in response to the application of an enabling signal on the control input thereof; means for applying said quadrature signals to the input of said gating circuit means; means coupling the output of said comparator circuit means to the control input of said gating circuit means to apply an enabling signal thereto whenever said first control voltage is greater than said second control voltage; and means for utilizing the output of said gating circuit means to produce color signals for reproduction by said television receiver.
Claim 3
Dependent Claim
27 words
The combination according to claim 1 wherein said first circuit means includes means for limiting the magnitude of said first demodulated signal to a predetermined maximum value.
Claim 4
Dependent Claim
111 words
The combination according to claim 1 Wherein said second circuit means produces said first control voltage representative of the absolute magnitude of demodulated signals in quadrature with said first demodulated signal and said means for applying said quadrature signals to the input of said gating circuit means comprises means for applying demodulated quadrature signals to such input, said combination further including third circuit means responsive to said composite signal for providing a signal representative of said brightness signal components at the output thereof and wherein said utilizing means is coupled to receive said signal representing said brightness signal components, said first demodulated signal and the output of said gating circuit means.
Claim 5
Dependent Claim
33 words
The combination according to claim 3 wherein the utilizing means comprises a matrix and said second coupling means comprises variable resistance means for enabling adjustment of the magnitude of said second control voltage.
Claim 6
Dependent Claim
275 words
An automatic hue control circuit for a color television receiver having a chrominance signal processing channel and in which the chrominance information signals applied thereto comprise a subcarrier signal modulated in phase and amplitude to represent hue and saturation of a color image, such hue and saturation being represented by signal components on first and second axes at quadrature with one another, said hue control circuit including in combination: means for separating said chrominance information into components corresponding to signals on said first and second axis; means coupled with said separating means for producing a first control signal representative of the absolute magnitude of said signals on said second axis; means coupled with said separating means for producing a second control signal having a magnitude which has a predetermined value relative to the magnitude of said signals on said first axis; a comparator having an output and first and second inputs connected to receive said first and second control signals, respectively, and producing an enabling signal on the output thereof whenever the magnitude of said first control signal is greater than the magnitude of said second control signal; a gate having a signal input, an output, and a control input; means for supplying said signal components on said second axis to the input of said gate; means coupling the output of said comparator with the control input of said gate for enabling said gate to pass signals from the input to the output thereof in response to an enabling signal from said comparator; and means for combining the output of said gate and said signals on said first axis to form a hue corrected signal.
Claim 7
Dependent Claim
275 words
An automatic hue control circuit for a color television receiver having a chrominance signal processing channel and in which the chrominance information signals applied thereto comprise a subcarrier signal modulated in phase and amplitude to represent hue and saturation of a color image, such hue and saturation being represented by signal components on first and second axes at quadrature with one another, said hue control circuit including in combination: means for separating said chrominance information into components corresponding to signals on said first and second axis; means coupled with said separating means for producing a first control signal representative of the absolute magnitude of said signals on said second axis; means coupled with said separating means for producing a second control signal having a magnitude which has a predetermined value relative to the magnitude of said signals on said first axis; a comparator having an output and first and second inputs connected to receive said first and second control signals, respectively, and producing an enabling signal on the output thereof whenever the magnitude of said first control signal is greater than the magnitude of said second control signal; a gate having a signal input, an output, and a control input; means for supplying said signal components on said second axis to the input of said gate; means coupling the output of said comparator with the control input of said gate for enabling said gate to pass signals from the input to the output thereof in response to an enabling signal from said comparator; and means for combining the output of said gate and said signals on said first axis to form a hue corrected signal.
Claim 8
Dependent Claim
21 words
The combination according to claim 5 wherein said first and second axes correspond respectively to the I and Q chrominance axes.
Claim 9
Dependent Claim
80 words
The combination according to claim 6 wherein said television receiver further includes a chroma amplifier circuit and a reference oscillator circuit with said separating means coupled to receive chrominance signals from said chroma amplifier; and wherein said means for producing said second control signal includes first demodulating means responsive to signals at a particular phase from said reference oscillator and said signals on said I axis for providing a demodulated I color representative signal corresponding to said second control signal.
Claim 10
Dependent Claim
26 words
The combination according to claim 7 wherein said demodulating means is a limiting demodulator which limits the maximum amplitude of said demodulated I color representative signal.
Claim 11
Dependent Claim
46 words
The combination according to claim 7 further including coupling circuit means connecting said demodulating means with the second input of said comparator, said coupling circuit including means for applying a predetermined fraction of said demodulated I color representative signal to the second input of said comparator.
Claim 12
Dependent Claim
16 words
The combination according to claim 9 wherein said coupling circuit means includes a variable resistance meaNs.
Claim 13
Dependent Claim
226 words
An automatic hue control circuit for a color television receiver having a chrominance signal processing channel and in which the chrominance information signals applied thereto comprise a subcarrier signal modulated in phase and amplitude to represent hue and saturation of a color image, such hue and saturation being represented by signal components on the first and second axes at quadrature with one another, said hue control circuit including in combination: means for separating said chrominance information into components corresponding to signals on said first and second axes; first means including peak detector means coupled with said separating means for producing a first control signal representative of the absolute magnitude of said signal on said second axis; second means coupled with said separating means for producing a second control signal having a magnitude which has a predetermined value relative to the magnitude of said signal components on said first axis; comparison circuit means having an output, and first and second inputs connected said first and second means to receive said first and second control signals, respectively, and producing an output signal on the output thereof indicative of the relative magnitudes of said first and second control signals; and means coupled with the output of said comparator circuit and responsive to said output signal for varying the hue of the color image reproduced by said color television receiver.
Claim 14
Dependent Claim
226 words
An automatic hue control circuit for a color television receiver having a chrominance signal processing channel and in which the chrominance information signals applied thereto comprise a subcarrier signal modulated in phase and amplitude to represent hue and saturation of a color image, such hue and saturation being represented by signal components on the first and second axes at quadrature with one another, said hue control circuit including in combination: means for separating said chrominance information into components corresponding to signals on said first and second axes; first means including peak detector means coupled with said separating means for producing a first control signal representative of the absolute magnitude of said signal on said second axis; second means coupled with said separating means for producing a second control signal having a magnitude which has a predetermined value relative to the magnitude of said signal components on said first axis; comparison circuit means having an output, and first and second inputs connected said first and second means to receive said first and second control signals, respectively, and producing an output signal on the output thereof indicative of the relative magnitudes of said first and second control signals; and means coupled with the output of said comparator circuit and responsive to said output signal for varying the hue of the color image reproduced by said color television receiver.
Claim 15
Dependent Claim
21 words
The combination according to claim 11 wherein the magnitude of said second control signal is limited to a predetermined maximum value.
Claim 16
Dependent Claim
41 words
The combination according to claim 12 wherein said second means includes a limiting demodulator, the maximum output of which is limited to a predetermined magnitude less than the maximum value which can be reached by signal components on said first axis.
References Cited (Backward Citations)
US3668306A
Cited
US3647941A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-12-02 | 1978-06-03 | 1978-12-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-12-02 | 1982-06-03 | 1982-12-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-12-02 | 1986-06-03 | 1986-12-03 | $7700.00 | Window Closed / Lapsed |