Patent US5638135A successfully refreshed from Google Patents.
US5638135A
Expired / Lapsed
US
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Digital color encoder with improved circuitry
Assignee: Ricoh Co Ltd
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Filing: 1996-04-04
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Granted: 1997-06-10
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Expires: 2016-04-04
Abstract
Abstract A digital encoder includes a matrix circuit for synthesizing chrominance signals R-Y and B-Y based on RGB signals sampled at a predetermined sampling frequency which is an integral multiple of a chrominance subcarrier; low-pass filters; a delay circuit; a switch circuit for reducing a frequency of an output from the low-pass filters; a digital modulator for subjecting a chrominance subcarrier to quadrature two-phase balanced modulation using an output signal from the switch circuit so as to output a chrominance signal having a sampling frequency 1/m that of the predetermined sampling frequency; a sampling frequency conversion circuit for multiplying the sampling frequency of the chrominance signal by a factor of m so as to output a chrominance signal having the predetermined sampling frequency; and an adder for computing a sum of the luminance signal delayed by the delay circuit, the chrominance signals output by the sampling frequency conversion circuit and a composite synchronizing signal so as to synthesize a composite video signal. In another construction, a digital color encoder of the present invention includes a matrix circuit for producing a luminance signal and chrominance signals by blending RGB signals using a predetermined ratio assigned to each color component; a trap filter for rejecting transmission of luminance signal components that correspond to a chrominance subcarrier frequency; a modulator for producing a chrominance signal having an arbitrary phase, based on the chrominance signals; an adder for producing a composite color signal by computing a sum of the luminance signal processed by the trap filter and the chrominance signal produced by the modulator.
Inventors
- 👤 Takuo Mukai
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 18:17
CPC Classifications
H; H04; H04N; H04N9/00; H04N9/64; H04N9/65; H04N11/00; H04N11/06; H04N11/12; H04N11/14; H04N11/143
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
155 words
A digital color encoder for producing a composite color signal from RGB signals, comprising: input means for importing RGB signals sampled at a sampling frequency which is an integral multiple of a chrominance subcarrier frequency; signal synthesizing means for blending the RGB signals imported by the input means using a predetermined ratio assigned to each color component so to produce a luminance signal and color difference signals; a low-pass filter receiving the luminance signal for subjecting said color difference signals to band rejection; a band-reject digital filter for rejecting transmission of luminance signal components that correspond to the chrominance subcarrier frequency; modulating means for producing a chrominance signal having an arbitrary phase, based on the color difference signals outputted from the low-pass filter; and adding means for synthesizing a composite color signal by computing a sum of the luminance signal processed by the band-reject digital filter and the chrominance signal produced by the modulating means.
Claim 2
Dependent Claim
155 words
A digital color encoder for producing a composite color signal from RGB signals, comprising: input means for importing RGB signals sampled at a sampling frequency which is an integral multiple of a chrominance subcarrier frequency; signal synthesizing means for blending the RGB signals imported by the input means using a predetermined ratio assigned to each color component so to produce a luminance signal and color difference signals; a low-pass filter receiving the luminance signal for subjecting said color difference signals to band rejection; a band-reject digital filter for rejecting transmission of luminance signal components that correspond to the chrominance subcarrier frequency; modulating means for producing a chrominance signal having an arbitrary phase, based on the color difference signals outputted from the low-pass filter; and adding means for synthesizing a composite color signal by computing a sum of the luminance signal processed by the band-reject digital filter and the chrominance signal produced by the modulating means.
Claim 3
Dependent Claim
21 words
The digital color encoder as claimed in claim 1, wherein said band-reject digital filter is embodied by a linear-phase moving-average filter.
Claim 4
Dependent Claim
21 words
The digital color encoder as claimed in claim 1, wherein said band-reject digital filter is embodied by a linear-phase notch-type filter.
Claim 5
Dependent Claim
51 words
The digital color encoder as claimed in claim 1, further comprising, in addition to a terminal for outputting the composite color signal, a signal terminal for outputting the luminance signal not processed by the band-reject digital filter; and a signal terminal for outputting the chrominance signal output by the modulating means.
Claim 6
Dependent Claim
41 words
The digital color encoder as claimed in claim 1, further comprising a switch means for selectively feeding to the adding means the luminance signal not processed by the band-reject digital filter or the luminance signal processed by the band-reject digital filter.
Claim 7
Dependent Claim
187 words
A digital color encoder connected to a color television set, comprising: signal synthesizing means for blending RGB signals sampled at a predetermined sampling frequency which is a/b times a chrominance subcarrier frequency, where a and b are integers, so as to produce a luminance signal and two color difference signals; low-pass filters for subjecting said color difference signals to band rejection; switch means for reducing a size of color difference data in said color difference signals subjected to band-rejection by the low-pass filters so as to convert a sampling frequency of said color difference signals into 1/m of said sampling frequency of said color difference signals, where m is an integer; modulating means for synthesizing a chrominance signal having an arbitrary phase, based on the two color difference signals have the converted sampling frequency; sampling frequency conversion means for converting a frequency of said chrominance signal into said predetermined sampling frequency; and adding means for synthesizing a composite video signal by computing a sum of said luminance signal, the chrominance signal having said predetermined sampling frequency and a composite synchronizing signal that conforms to a predetermined standard.
Claim 8
Dependent Claim
187 words
A digital color encoder connected to a color television set, comprising: signal synthesizing means for blending RGB signals sampled at a predetermined sampling frequency which is a/b times a chrominance subcarrier frequency, where a and b are integers, so as to produce a luminance signal and two color difference signals; low-pass filters for subjecting said color difference signals to band rejection; switch means for reducing a size of color difference data in said color difference signals subjected to band-rejection by the low-pass filters so as to convert a sampling frequency of said color difference signals into 1/m of said sampling frequency of said color difference signals, where m is an integer; modulating means for synthesizing a chrominance signal having an arbitrary phase, based on the two color difference signals have the converted sampling frequency; sampling frequency conversion means for converting a frequency of said chrominance signal into said predetermined sampling frequency; and adding means for synthesizing a composite video signal by computing a sum of said luminance signal, the chrominance signal having said predetermined sampling frequency and a composite synchronizing signal that conforms to a predetermined standard.
Claim 9
Dependent Claim
31 words
The digital color encoder as claimed in claim 6, wherein said modulating means includes two multipliers operated at 1/m of said predetermined sampling frequency in processing said two color difference signals.
Claim 10
Dependent Claim
33 words
The digital color encoder as claimed in claim 6, wherein said modulating means includes a multiplier operated at said predetermined sampling frequency in processing said two color difference signals using a time-division scheme.
Claim 11
Dependent Claim
85 words
The digital color encoder as claimed in claim 6, wherein said sampling frequency conversion means multiplies the sampling frequency of said chrominance signal by a factor of n instead of m, where n is an integer, said digital color encoder further comprising luminance signal frequency conversion means for multiplying the sampling frequency of said luminance signal by a factor of n/m so that the sampling frequencies of said luminance signal and said chrominance signal are harmonized before the sum is produced by the adding means.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2000-06-09 | 2000-12-09 | 2001-06-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2004-06-09 | 2004-12-09 | 2005-06-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2008-06-09 | 2008-12-09 | 2009-06-10 | $7700.00 | Window Closed / Lapsed |