Patent US3236284A successfully refreshed from Google Patents.
Patent US3825673A successfully refreshed from Google Patents.
US3825673A
Expired / Lapsed
US
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Color gamut compressor
Assignee: Thomas International Corp
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Filing: 1971-03-04
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Granted: 1974-07-23
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Expires: 1991-03-04
Abstract
Abstract A gamut compressor circuit in the chroma channel of a color television receiver selectively changes the effective angle between the demodulation axes of a two axis demodulation system to visually minimize hue errors in the orange (flesh tone) and cyan regions. Apparatus is also provided to substitute a reference hue control when the gamut compressor circuit is in use.
Inventors
- 👤 J Furrey
- 👤 Crenn G Le
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 14:37
CPC Classifications
H; H04; H04N; H04N9/00; H04N9/64; H04N9/643
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
178 words
A chrominance channel for a received composite color television signal which includes a chrominance component having a phase variable with respect to a phase reference component to represent chrominance information, comprising: demodulator means with at least two demodulator stages each demodulating said chrominance component along a different demodulation axis; a reference signal means for generating a separate demodulating signal for each demodulator stage with each separate demodulating signal having a different selected phase angle with respect to said reference component, the phase difference between two of said separate demodulating signals being fixed; phase shift means effective when enabled to change the selected phase angle of at least one separate demodulating signal in a direction to change the fixed phase difference between said two separate demodulating signals; said demodulator means being responsive to said demodulating signals for demodulating said chrominance component along said phase sensitive demodulation axes directly related to the phase angles of said demodulating signals; and switch means for selectively enabling and disabling said phase shift means to selectively shift the demodulation axis of said demodulating means.
Claim 2
Dependent Claim
178 words
A chrominance channel for a received composite color television signal which includes a chrominance component having a phase variable with respect to a phase reference component to represent chrominance information, comprising: demodulator means with at least two demodulator stages each demodulating said chrominance component along a different demodulation axis; a reference signal means for generating a separate demodulating signal for each demodulator stage with each separate demodulating signal having a different selected phase angle with respect to said reference component, the phase difference between two of said separate demodulating signals being fixed; phase shift means effective when enabled to change the selected phase angle of at least one separate demodulating signal in a direction to change the fixed phase difference between said two separate demodulating signals; said demodulator means being responsive to said demodulating signals for demodulating said chrominance component along said phase sensitive demodulation axes directly related to the phase angles of said demodulating signals; and switch means for selectively enabling and disabling said phase shift means to selectively shift the demodulation axis of said demodulating means.
Claim 3
Dependent Claim
84 words
The chrominance channel of claim 1 wherein said phase shift means is effective when enabled to change the selected phase angle of a first demodulating signal to a first different phase angle with respect to said reference component and to change the selected phase angle of a second demodulating signal to a second different phase angle with respect to said reference component, the phase difference between said first different phase angle and said second different phase angle being different than said fixed phase difference.
Claim 4
Dependent Claim
70 words
The chrominance channel of claim 2 wherein said reference signal means includes a first phase shift network for phase shifting said first demodulating signal and a second phase shift network for phase shifting said second demodulating signal, and said phase shift means includes impedance means coupled in common with said first and second phase shift networks for relatively changing the phase angle of both said first and second demodulating signals.
Claim 5
Dependent Claim
65 words
The chrominance channel of claim 3 wherein said first phase shift network produces a demodulating signal phase leading said reference component and said second phase shift network produces an insertion signal phase lagging said reference component, and said common impedance means comprises impedance means having an impedance value controlled by said switch means to rotate in opposite directions the phase angles of said insertion signals.
Claim 6
Dependent Claim
72 words
The invention of claim 1 further comprising hue control means including variable impedance means having a range of impedance values for controlling the phase relationship between said demodulating signals and said chrominance signal, and a reference impedance having a predetermined impedance within said range of impedances, said switch means being effective to substitute said reFerence impedance for said variable impedance when said phase shift means is enabled to introduce a reference hue.
Claim 7
Dependent Claim
80 words
The apparatus of claim 1 further comprising a hue control means including a first variable impedance having a predetermined range of impedance values for introducing a variable phase shift in one of said chrominance signal and demodulating signals, a second impedance connectable in parallel with said variable impedance when said switch is positioned to enable said phase shift means, said switch when positioned to disable said phase to shift means also functioning to remove said second impedance from the circuit.
Claim 8
Dependent Claim
36 words
The apparatus of claim 6 wherein said switch, when positioned to disable said phase shift means, further functions to short circuit a portion of said variable impedance to thereby increase the range of obtainable impedance values.
Claim 9
Dependent Claim
164 words
In a color television system using a receiver having at least two chroma demodulator stages each sensitive along a different demodulation axis with the angular displacement therebetween having a predetermined value to reproduce an approximate linear transposition of colors transmitted by phase modulation with respect to a reference phase, the improvement for producing a color gamut compression in a selected color quadrant defined by the demodulation axes of said two chroma demodulator stages, comprising: reference means for providing a reference phase signal corresponding to said reference phase; phase shift means coupled to said reference means for generating at least two demodulating signals each having a separate phase angle with respect to said reference phase signal, the phase difference between said separate phase angles being different than said predetermined value; and means coupling said phase shift means to said demodulator stages to shift the demodulating axes in a rotational direction relative to each other to narrow the angular displacement therebetween in the selected color quadrant.
Claim 10
Dependent Claim
164 words
In a color television system using a receiver having at least two chroma demodulator stages each sensitive along a different demodulation axis with the angular displacement therebetween having a predetermined value to reproduce an approximate linear transposition of colors transmitted by phase modulation with respect to a reference phase, the improvement for producing a color gamut compression in a selected color quadrant defined by the demodulation axes of said two chroma demodulator stages, comprising: reference means for providing a reference phase signal corresponding to said reference phase; phase shift means coupled to said reference means for generating at least two demodulating signals each having a separate phase angle with respect to said reference phase signal, the phase difference between said separate phase angles being different than said predetermined value; and means coupling said phase shift means to said demodulator stages to shift the demodulating axes in a rotational direction relative to each other to narrow the angular displacement therebetween in the selected color quadrant.
Claim 11
Dependent Claim
37 words
The improvement of claim 8 wherein said phase shift means generates said two demodulating signals at separate phase angles which narrows said angular displacement in opposed color quadrants containing the generally complementary hues of cyan and orange.
Claim 12
Dependent Claim
84 words
A gamut compression circuit for the chrominance channel of a receiver adapted to receive a composite color television signal which includes a chrominance component having a phase variable with respect to a phase reference component to represent chrominance information, said gamut compression circuit comprises: means for demodulating said chrominance component along at least two different effective demodulation axes to reproduce the transmitted color imformation and means for selectively, relatively shifting said axes to change the angle therebetween to cause gamut compression in predetermined regions.
Claim 13
Dependent Claim
84 words
A gamut compression circuit for the chrominance channel of a receiver adapted to receive a composite color television signal which includes a chrominance component having a phase variable with respect to a phase reference component to represent chrominance information, said gamut compression circuit comprises: means for demodulating said chrominance component along at least two different effective demodulation axes to reproduce the transmitted color imformation and means for selectively, relatively shifting said axes to change the angle therebetween to cause gamut compression in predetermined regions.
Claim 14
Dependent Claim
113 words
The apparatus of claim 10 wherein said means for demodulating said chrominance component comprises at first and second phase sensitive demodulators and further comprising means for deriving a pair of demodulating reference signals from said phase reference component, means coupling said demodulating reference components to respective first inputs of said demodulators and said chrominance signal to respective second inputs of said demodulators to cause said first and second demodulators to demodulate said chrominance signal along different respective first and second demodulation axes and phase shift means for selectively varying the phase difference between the signals on one of said respective first and second inputs to thereby vary the angle between said demodulation axes.
Claim 15
Dependent Claim
26 words
The apparatus of claim 11 wherein said phase shift means comprises means for selectively varying the phase of at least one of said demodulating reference signals.
Claim 16
Dependent Claim
24 words
The apparatus of claim 11 wherein phase shift means comprises means to selectively phase shift both of said demodulating reference signals in opposite directions.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-07-22 | 1978-01-21 | 1978-07-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-07-22 | 1982-01-21 | 1982-07-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-07-22 | 1986-01-21 | 1986-07-23 | $7700.00 | Window Closed / Lapsed |