US3555176A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Color demodulator
Assignee: Motorola Solutions Inc
•
Filing: 1968-05-31
•
Granted: 1971-01-12
•
Expires: 1988-05-31
Abstract
Abstract A color demodulator for a color television receiver uses three separate demodulators each having a pair of diodes to separately demodulate the three color signals. The polarity of the pair of diodes used to demodulate one color is reversed from the polarity of the diodes used the other two colors in order to provide the proper phase angles necessary to carry out the demodulation.
Inventors
- 👤 Gildo Cecchin
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 07:40
CPC Classifications
H; H04; H04N; H04N9/00; H04N9/64; H04N9/66
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
223 words
A demodulator circuit for a color television receiver including in combination, chrominance signal input means adapted to receive a chrominance signal, reference signal input means adapted to receive a reference signal, first, second and third demodulator means, first phase-shifting means coupling one of said reference signal input means or said chrominance signal input means to said first demodulator means for shifting the relative phase of said reference signal and said chrominance signal by a first predetermined amount, the other signal input means being coupled directly to said first demodulator means, second phase shifting means coupling one of said reference signal input means or said chrominance signal input means to said second demodulator means for shifting the relative phase of said reference signal and said chrominance signal by a second predetermined amount, the other signal input means being coupled directly to said second demodulator means, and circuit means coupling said reference signal input means and said chrominance signal input means directly to said third demodulator means for applying said reference signal and said chrominance signal thereto, each of said first, second and third demodulator means including switching means, said switching means being so arranged that the polarity of said switching means of said third demodulator means is reversed with respect to the polarity of said switching means of said first and second demodulator means.
Claim 2
Dependent Claim
223 words
A demodulator circuit for a color television receiver including in combination, chrominance signal input means adapted to receive a chrominance signal, reference signal input means adapted to receive a reference signal, first, second and third demodulator means, first phase-shifting means coupling one of said reference signal input means or said chrominance signal input means to said first demodulator means for shifting the relative phase of said reference signal and said chrominance signal by a first predetermined amount, the other signal input means being coupled directly to said first demodulator means, second phase shifting means coupling one of said reference signal input means or said chrominance signal input means to said second demodulator means for shifting the relative phase of said reference signal and said chrominance signal by a second predetermined amount, the other signal input means being coupled directly to said second demodulator means, and circuit means coupling said reference signal input means and said chrominance signal input means directly to said third demodulator means for applying said reference signal and said chrominance signal thereto, each of said first, second and third demodulator means including switching means, said switching means being so arranged that the polarity of said switching means of said third demodulator means is reversed with respect to the polarity of said switching means of said first and second demodulator means.
Claim 3
Dependent Claim
75 words
The demodulator circuit of claim 1 wherein, each of said switching means includes a pair of diodes arranged to receive said chrominance and said reference signals to demodulate said chrominance signal, the polarity of said pair of diodes in said switching means of said third demodulator means being reversed with respect to the polarity of corresponding ones of said pair of diodes in each of said switching means of said first and second demodulator means.
Claim 4
Dependent Claim
135 words
The demodulator circuit of claim 1 wherein, said chrominance signal input means includes first and second output means, with the phase of said chrominance signal appearing at said first output means being 180* from the phase of said chrominance signal appearing at said second output means, each of said demodulator switching means including a first diode coupled to said first output means and a second diode coupled to said second output means, the polarity of said first diode of said third demodulator means being reversed with respect to the polarity of said first diode in each of said first and second demodulator means, and the polarity of said second diode in said third demodulator means being reversed with respect to the polarity of said second diode in each of said first and second demodulator means.
Claim 5
Dependent Claim
43 words
The demodulator circuit of claim 3 wherein, the phase angle of the demodulated output of said third demodulator means has a particular phase angle, said reference signal applied to said third demodulator means having a phase angle 180* from said particular phase angle.
Claim 6
Dependent Claim
118 words
The demodulator circuit of claim 3 wherein, said chrominance signal has R-Y, B-Y and G-Y phase angles, said first demodulator is an R-Y demodulator, said second demodulator is a B-Y demodulator and said third demodulator is a G-Y demodulator, said reference signal having a phase angle equal to minus said G-Y phase angle, said first phase shifting means coupling said reference signal to said first demodulator means with said reference signal shifted to said R-Y phase angle, said second phase shifting means coupling said reference signal to said second demodulator means with said rEference signal shifted to said B-Y phase angle, the amount of said first and second predetermined amounts of phase shift each being less than 90*.
Claim 7
Dependent Claim
72 words
The demodulator circuit of claim 5 wherein, said chrominance signal input means is further adapted to receive a brightness signal, and couple the same to said first, second and third demodulator means, each of said demodulator means including demodulator output impedance means, said brightness signal combining with said demodulated chrominance signals across said output impedance means of said first, second and third demodulators to develop red, blue and green chroma signals respectively.
Claim 8
Dependent Claim
173 words
A demodulator circuit for a color television receiver including in combination, chrominance signal input means adapted to receive a chrominance signal, reference signal input means adapted to receive a reference signal, first, second and third demodulator means each coupled to said reference signal input means, first phase shifting means coupling said chrominance signal input means to said first demodulator means for shifting the phase of said chrominance signal by a first predetermined amount, second phase shifting means coupling said chrominance signal input means to said second demodulator means for shifting the phase of said chrominance signal by a second predetermined amount, and circuit means coupling said chrominance signal input means directly to said third demodulator means for applying said chrominance signal thereto, each of said first, second and third demodulator means including diode means, said diode means being so arranged that the polarity of said diode means of said third demodulator means is reversed with respect to the polarity of corresponding ones of said diode means of said first and second demodulator means.
Claim 9
Dependent Claim
173 words
A demodulator circuit for a color television receiver including in combination, chrominance signal input means adapted to receive a chrominance signal, reference signal input means adapted to receive a reference signal, first, second and third demodulator means each coupled to said reference signal input means, first phase shifting means coupling said chrominance signal input means to said first demodulator means for shifting the phase of said chrominance signal by a first predetermined amount, second phase shifting means coupling said chrominance signal input means to said second demodulator means for shifting the phase of said chrominance signal by a second predetermined amount, and circuit means coupling said chrominance signal input means directly to said third demodulator means for applying said chrominance signal thereto, each of said first, second and third demodulator means including diode means, said diode means being so arranged that the polarity of said diode means of said third demodulator means is reversed with respect to the polarity of corresponding ones of said diode means of said first and second demodulator means.
Claim 10
Dependent Claim
75 words
The demodulator circuit of claim 7 wherein, each of said switching means includes a pair of diodes arranged to receive said chrominance and said reference signals to demodulate said chrominance signal, the polarity of said pair of diodes in said switching means of said third demodulator means being reversed with respect to the polarity of corresponding ones of said pair of diodes in each of said switching means of said first and second demodulator means.
References Cited (Backward Citations)
US3133987A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-01-11 | 1974-07-13 | 1975-01-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-01-11 | 1978-07-13 | 1979-01-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-01-11 | 1982-07-13 | 1983-01-12 | $7700.00 | Window Closed / Lapsed |