US3662097A
Expired / Lapsed
US
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Chroma processing circuitry with selectable color correction mode
Assignee: Zenith Electronics LLC
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Filing: 1970-05-18
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Granted: 1972-05-09
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Expires: 1990-05-18
Abstract
Abstract Chroma processing circuitry for a color television receiver wherein nominally derived primary color signals in accordance with extracted reference information in a first selectable mode of operation may be suitably modified in a second selectable mode of operation to minimize the effect of any phase errors otherwise readily discernible as undesirable departures in fleshtone hues. The referenced modification comprises a predetermined reduction in green-purple color information relative to derived luminance and orange-cyan information. Three embodiments are disclosed. In one such embodiment employing I and Q demodulation techniques, the chroma signal as applied to the input of the included Q demodulator is selectively reduced by associated control circuitry; the signal information along the Q axis or demodulation angle representing essentially green-purple color information. In another embodiment, employing convention (R-Y) and (B-Y) color difference demodulators, the desired reduction in green-purple information is provided by suitable alteration of the respective phase delays effected in components of the reference signal selectively applied to the demodulators which in turn alters each of the demodulation angles at which such demodulators operate. In still another embodiment, appropriate modification of the final primary color signals is accomplished by selected changes in the circuit parameters of an output matrix network associated with the color difference demodulators.
Inventors
- 👤 John L Rennick
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 18:37
CPC Classifications
H; H04; H04N; H04N9/00; H04N9/64; H04N9/643
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
170 words
In a color television receiver including an image reproducer and signal processing circuitry for extracting luminance iNformation from a main carrier and respective color reference signals from a subcarrier modulated with essentially orange-cyan color information along a first axis and essentially green-purple color information along a second axis in quadrature with said first axis, chroma processing apparatus for producing an image in color having selectable modes of operation, including in combination: circuit means for deriving a plurality of primary color signals from said luminance and color information signals for utilization by the image reproducer, and control means having a selectable position defining a first mode of operation in which the relative magnitudes of said primary color signals are substantially as determined by said extracted luminance and color information signals, and a further and additional selectable position defining a second mode of operation in which said green-purple color information in said derived primary color signals is reduced to a predetermined but finite amount relative to the luminance and orange-cyan color information.
Claim 2
Dependent Claim
170 words
In a color television receiver including an image reproducer and signal processing circuitry for extracting luminance iNformation from a main carrier and respective color reference signals from a subcarrier modulated with essentially orange-cyan color information along a first axis and essentially green-purple color information along a second axis in quadrature with said first axis, chroma processing apparatus for producing an image in color having selectable modes of operation, including in combination: circuit means for deriving a plurality of primary color signals from said luminance and color information signals for utilization by the image reproducer, and control means having a selectable position defining a first mode of operation in which the relative magnitudes of said primary color signals are substantially as determined by said extracted luminance and color information signals, and a further and additional selectable position defining a second mode of operation in which said green-purple color information in said derived primary color signals is reduced to a predetermined but finite amount relative to the luminance and orange-cyan color information.
Claim 3
Dependent Claim
77 words
Improved chroma processing apparatus for a color television receiver in accordance with claim 1 wherein said circuit means includes respective I and Q demodulators and associated matrix network means coupled to said demodulators to utilize the outputs therefrom and wherein said control means includes additional circuit means to selectively alter the level of color information as applied to said I and Q demodulators when changing from one selectable mode of operation to the other of said modes.
Claim 4
Dependent Claim
44 words
Improved chroma processing apparatus for a color television receiver in accordance with claim 2 wherein said control means comprises switch means which when actuated to define said second mode of operation selectively reduces the level of color information as applied to said Q demodulator.
Claim 5
Dependent Claim
81 words
Improved chroma processing apparatus for a color television receiver in accordance with claim 1 wherein said circuit means includes respective (R-Y) and (B-Y) color difference demodulators and associated matrix network means coupled to said demodulators to utilize the outputs therefrom and wherein said control means includes means for operating said demodulators along given demodulation angles, respectively, in said first selectable mode of operation and along predetermined demodulation angles, respectively, in said second mode of operation differing from said given demodulation angles.
Claim 6
Dependent Claim
111 words
Improved chroma processing apparatus for a color television receiver in accordance with claim 4 wherein said means for selectively establishing said selectable demodulation angles comprises a phase shift network having a plurality of interconnected reactive circuit elements forming first and second signal paths therethrough of predetermined phase delays to define said first mode of operation, and a further and additional reactive circuit element which when actively coupled to said phase shift network provides a predetermined alteration in the phase delay through each of said first and second signal paths, and switch means for detachably interconnecting said additional reactive circuit element in said phase shift network in said second mode of operation.
Claim 7
Dependent Claim
99 words
Improved chroma processing apparatus for a color television receiver in accordance with claim 1 wherein said circuit means includes a demodulation system developing (R-Y), (B-Y) and (G-Y) color difference signals and an associated video matrix means having respective matrix amplifiers which collectively exhibit given gain and matrix transfer constants and which individually utilize said respective color difference signals in conjunction with the extracted luminance information to derive primary color signals, and wherein said control means in defining said second mode of operation is effective to selectively alter the gain and matrix transfer constants for each of said matrix amplifiers.
Claim 8
Dependent Claim
97 words
Improved chroma processing apparatus for a color television receiver in aCcordance with claim 6 wherein said plurality of matrix amplifiers includes first, second and third semiconductor devices each having input, output and common electrodes and wherein said control means includes switch means having a first switch portion which when actuated provides a signal path between the common electrodes of said semiconductor devices serving as red and blue matrix amplifiers and a second switch portion which when actuated reduces by a predetermined amount the level of each of said color difference signals as developed by said demodulator system.
Claim 9
Dependent Claim
139 words
Improved chroma processing apparatus for a color television receiver in accordance with claim 1 wherein said control means in said one selectable position defining said first mode of operation provides red, green and blue color signals of given relative magnitudes and having an angular displacement of approximately 105* between said red and blue primary color signals and between said blue and green primary signals, and an angular displacement of approximately 150* between said green and red primary color signals, and wherein said other selectable position defining said second mode of operation provides an angular displacement between said red and blue primary color signals on the order of 135* to 145*, and which further reduces the magnitude of said derived green primary color signal by a predetermined amount relative to the magnitudes of said red and blue primary color signals.
Claim 10
Dependent Claim
182 words
In a color television receiver with signal translating circuitry and an image reproducer for reproducing a televised image in color, chroma processing apparatus, comprising in combination: means for extracting luminance information from a main carrier and for extracting respective color reference information from a subcarrier along first and second reference axes in phase quadrature; fleshtone tint stabilizing means including selectable control means which upon actuation modifies the extracted color reference information along one of said reference axis by de-emphasizing the same relative to that along said other reference axis and said luminance information; and circuit means for utilizing said modified color reference information and said other unmodified color reference information and said luminance information substantially as extracted to form a plurality of particularized primary color signals for application to the image reproducer wherein color signal information at respective angular intervals between said reference axes is progressively diminished in magnitude in a direction toward said reference axis representing said modified color reference information and which is effectively shifted in phase in a direction toward said reference axis representing said unmodified color reference information.
Claim 11
Dependent Claim
182 words
In a color television receiver with signal translating circuitry and an image reproducer for reproducing a televised image in color, chroma processing apparatus, comprising in combination: means for extracting luminance information from a main carrier and for extracting respective color reference information from a subcarrier along first and second reference axes in phase quadrature; fleshtone tint stabilizing means including selectable control means which upon actuation modifies the extracted color reference information along one of said reference axis by de-emphasizing the same relative to that along said other reference axis and said luminance information; and circuit means for utilizing said modified color reference information and said other unmodified color reference information and said luminance information substantially as extracted to form a plurality of particularized primary color signals for application to the image reproducer wherein color signal information at respective angular intervals between said reference axes is progressively diminished in magnitude in a direction toward said reference axis representing said modified color reference information and which is effectively shifted in phase in a direction toward said reference axis representing said unmodified color reference information.
Claim 12
Dependent Claim
49 words
Improved chroma processing apparatus for a color television receiver in accordance with claim 9 wherein said first and second reference axes represent nominal I and Q axes, respectively, and wherein said modified color reference information represents essentially green-purple information and said unmodified color reference information represents essentially orange-cyan information.
References Cited (Backward Citations)
US2888514A
Cited
US3525802A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-05-09 | 1975-11-08 | 1976-05-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-05-09 | 1979-11-08 | 1980-05-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-05-09 | 1983-11-08 | 1984-05-09 | $7700.00 | Window Closed / Lapsed |