US3566017A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Television color difference signal encoding system
Assignee: RCA Corp
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Filing: 1969-03-06
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Granted: 1971-02-23
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Expires: 1989-03-06
Abstract
Abstract Each of the (B-Y) and (R-Y) sideband signals of two suppressed color carrier waves derived from a camera tube having a spatial color difference signal encoding filter is envelope detected and positive and negative polarities of the detected signal are developed, the proper polarity being selected to produce an unambiguous output signal by a switch controlled by a correct polarity indicating signal. The color carrier wave derived from the camera tube also is amplitude limited, doubled in frequency and applied to a controllable phase-frequency divider to produce an unambiguous reference wave of the suppressed color carrier wave frequency which is compared in phase with the signal modulated color carrier wave derived from the camera tube to produce the correct phase indicating signal which controls the switch. The frequency divider is controlled by a correcting signal produced by comparing the divider output with a phasing pulse generated during each horizontal scanning line. The phasing pulse is generated by projecting light from an external source through a narrow strip of filter material onto the camera tube area which is scanned during each horizontal raster line.
Inventors
- 👤 Albert Macovski
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 15:42
CPC Classifications
H; H04; H04N; H04N9/00; H04N9/03
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
238 words
In a color television system in which light from a colored subject is projected onto the photosensitive electrode of a camera tube through a color difference signal encoding filter and the electrode is scanned by an electron beam in a raster of vertically spaced horizontal lines to produce at least one color difference signal in the form of an amplitude modulated suppressed color carrier wave having a polarity ambiguity because of the suppression of the carrier wave, an unambiguous encoding system, comprising: detection means responsive to a given frequency band of the sidebands of said color carrier wave for producing positive and negative polarities of said signal modulated color carrier wave envelope constituting said color difference signal; controllable selection means for selecting either one of said color carrier wave envelope polarities to produce an output color difference signal; means for generating a phasing pulse at the start of each horizontal scanning line; wave developing means responsive to said phasing pulse for producing throughout each scanning line an unmodulated constant phase unambiguous reference wave having said color carrier wave frequency; signal producing means responsive to said signal modulated color carrier wave and to said reference wave for developing an indicating signal representative of the correct phase of said signal modulated color carrier wave; and means for impressing said indicating signal upon said selection means to so control it that its produced output color difference signal is of unambiguous polarity.
Claim 2
Dependent Claim
238 words
In a color television system in which light from a colored subject is projected onto the photosensitive electrode of a camera tube through a color difference signal encoding filter and the electrode is scanned by an electron beam in a raster of vertically spaced horizontal lines to produce at least one color difference signal in the form of an amplitude modulated suppressed color carrier wave having a polarity ambiguity because of the suppression of the carrier wave, an unambiguous encoding system, comprising: detection means responsive to a given frequency band of the sidebands of said color carrier wave for producing positive and negative polarities of said signal modulated color carrier wave envelope constituting said color difference signal; controllable selection means for selecting either one of said color carrier wave envelope polarities to produce an output color difference signal; means for generating a phasing pulse at the start of each horizontal scanning line; wave developing means responsive to said phasing pulse for producing throughout each scanning line an unmodulated constant phase unambiguous reference wave having said color carrier wave frequency; signal producing means responsive to said signal modulated color carrier wave and to said reference wave for developing an indicating signal representative of the correct phase of said signal modulated color carrier wave; and means for impressing said indicating signal upon said selection means to so control it that its produced output color difference signal is of unambiguous polarity.
Claim 3
Dependent Claim
71 words
In a color television system, an unambiguous encoding system as defined in claim 1, wherein: said wave developing means includes a frequency multiplier responsive to said color carrier wave for producing an auxiliary wave having said color carrier wave frequency increased by an even number factor; and a controllable phase frequency divider coupled to the output of said frequency multiplier for producing an unmodulated wave having said color carrier wave frequency.
Claim 4
Dependent Claim
93 words
In a color television system, an unambiguous encoding system as defined in claim 2, wherein: said wave developing means also includes comparison means for comparing said unmodulated wave produced by said frequency divider with said phasing pulse to produce a phase correcting signal representative of an out-of-phase condition of said phasing pulse and said unmodulated frequency divider output wave; and means for impressing said phase correcting signal upon said frequency divider to reverse the phase of said unmodulated frequency divider output wave so as to bring it into phase with said phasing pulse.
Claim 5
Dependent Claim
77 words
In a color television system, an unaMbiguous encoding system as defined in claim 3, wherein: said wave developing means further includes a gate having (1) an input circuit coupled to receive said phasing pulse, (2) an output circuit coupled to said comparison means, and (3) a control circuit; and means for impressing a gate operating pulse upon said control circuit at the start of each horizontal scanning line to transmit said phasing pulse to said comparison means.
Claim 6
Dependent Claim
72 words
In a color television system, an unambiguous encoding system as defined in claim 4, wherein: said wave developing means additionally includes an amplitude limiter coupled to the input of said frequency multiplier to impress a constant amplitude color carrier wave upon said frequency multiplier; and wherein: said frequency multiplier is a frequency doubler; said frequency divider is a binary counter; and said comparison means and said signal producing means are synchronous detectors.
Claim 7
Dependent Claim
63 words
In a color television system, an unambiguous encoding system as defined in claim 5, wherein: said detection means includes an envelope detector responsive to said color difference signal modulated carrier wave to produce a demodulated color difference signal; and a phase splitter coupled to said envelope detector for developing at respective output terminals positive and negative polarities of said demodulated color difference signal.
Claim 8
Dependent Claim
56 words
In a color television system, an unambiguous encoding system as defined in claim 6, wherein: said selection means comprises a switch operable to effectively connect a color difference signal output terminal to either of the output terminals of said phase splitter; and means including said indicating signal derived from said comparison means for operating said switch.
Claim 9
Dependent Claim
70 words
In a color television system, an unambiguous encoding system as defined in claim 1, wherein: said means for generating a phasing signal at the start of each horizontal scanning line comprises: a narrow vertical strip in a position at one side of said raster to be scanned at the start of each horizontal scanning line; and means for illuminating said strip by light independent of light derived from said subject.
Claim 10
Dependent Claim
40 words
In a color television system, a phasing signal generating means as defined in claim 8, wherein: said vertical strip is an opaque phosphor which masks out light from said subject; and said illuminating means is a source of ultraviolet radiation.
Claim 11
Dependent Claim
105 words
In a color television system, an unambiguous encoding system as defined in claim 1, wherein said means for generating a phasing signal at the start of each horizontal scanning line comprises: means for projecting from a light source a small amount of additive light of at least one color through said color difference signal encoding filter over said photosensitive camera tube electrode; and a narrow vertical strip of filter material to pass light of said given color located between said subject and said color difference signal encoding filter at one side of said raster to be scanned at the start of each horizontal scanning line.
Claim 12
Dependent Claim
70 words
In a color television system, a phasing signal generating means as defined in claim 10, wherein: said color difference signal encoding filter is of a character to encode blue and red color difference signals on two suppressed carrier waves of respectively different frequencies; said additive light is green; and said strip filter material is of a character to pass said additive green light and any green light from said subject.
Claim 13
Dependent Claim
49 words
In a color television system, a phasing signal generating means as defined in claim 11, wherein: said light from said source is white; and said light projecting means includes a collimating lens and a green light passing filter to uniformly illuminate said photosensitive camera tube electrode with green light.
Claim 14
Dependent Claim
70 words
In a color television system, a phasing signal generating means as defined in claim 10, wherein: said color difFerence signal encoding filter is of a character to encode blue and red color difference signals on two suppressed carrier waves of respectively different frequencies; said additive light is magenta; and said strip filter material is of a character to pass said additive magenta light and any magenta light from said subject.
Claim 15
Dependent Claim
49 words
In a color television system, a phasing signal generating means as defined in claim 13, wherein: said light from said source is white; and said light projecting means includes a collimating lens and a magenta light passing filter to uniformly illuminate said photosensitive camera tube electrode with magenta light.
Claim 16
Dependent Claim
98 words
In a color television system, an unambiguous encoding system as defined in claim 1, wherein said means for generating a phasing signal at the start of each horizontal scanning line comprises: a point source of white light; a grating of alternating strips of filter material for passing complementary colors of white light in equal amounts; and means for projecting light from said point source through said grating onto the photosensitive electrode of said camera tube, the scansion of said photosensitive camera tube electrode area corresponding to the first one of said alternating grating strips producing said phasing signal.
Claim 17
Dependent Claim
66 words
In a color television system, a phasing signal generating system as defined in claims 15, wherein: the width and number of said alternating strips of filter material in said grating is such that the scansion of said photosensitive camera tube electrode produces a suppressed carrier wave of a frequency outside of the given frequency band of said color carrier wave sidebands impressed upon said detection means.
Claim 18
Dependent Claim
60 words
In a color e television system, a phasing signal generating means as defined in claim 16, wherein: said color difference signal encoding filter is of a character to encode blue and red color difference signals on two suppressed carrier waves of respectively different frequencies; and said alternating strips of filter material in said grating pass green and magenta light respectively.
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) | 1974-02-22 | 1974-08-24 | 1975-02-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-02-22 | 1978-08-24 | 1979-02-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-02-22 | 1982-08-24 | 1983-02-23 | $7700.00 | Window Closed / Lapsed |