US3921206A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of and system for generating video signals in color television
Assignee: Canon Inc
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Filing: 1973-12-28
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Granted: 1975-11-18
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Expires: 1993-12-28
Abstract
Abstract A photosensitive pick-up screen of a color-television camera is overlain by a strip mask through which light from an object is projected onto the screen for scanning, as by an electron beam, to produce electrical output signals in the form of discrete pulses representative of successive image dots. The strips of the mask, intersecting the lines of scan, are alternately transparent and color-selective, the latter strips suppressing alternately two additive primary colors such as red and blue so as to provide luminance signals Y and color-difference signals Y-R, Y-B in a recurrent four-pulse sequence Y / Y-R / Y / Y-B. The pulses of this sequence, separated from one another by means of timercontrolled switches, are individually delayed by one pulse length Tau in a storage circuit from which they are fed to subtractors deriving first and second chrominance signals R1, B1 or R2, B2 from each color-difference signal and the immediately preceding or succeeding luminance signal. The chrominance signals R and B, besides being delivered to an outgoing transmission channel via an output matrix deriving therefrom a signal (G) for the third primary color, are combined in an adder with complementary colordifference signals Y-R and Y-B, respectively, to reconstitute the luminance signal Y during pulse periods when this signal is not directly available from the screen output so that the brightness pulses recur with a period Tau . A threshold circuit monitors the passing of color boundaries, appearing as sharp changes in signal strength during a pulse period, and thereupon causes the adder to switch from the first chrominance signal R1 or R2 to the second chrominance signal B1 or B2.
Inventors
- 👤 Kurt Bohm
- 👤 Robert Scheiber
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 03:47
CPC Classifications
H; H04; H04N; H04N23/00; H04N23/10; H04N23/12
Claims Analysis
Total Claims: 19
Claim 1
Independent Claim
308 words
A system for generating luminance and color signals for the transmission of color-television images over an outgoing video channel, comprising: a photosensitive screen adapted to receive the projected image of an object; a mask interposed between said screen and the location of said object, said mask being subdivided into a multiplicity of parallel strips of different light transmissivity, said strips being divided into groups of four with an invariable sequence of a first transparent strip passing all three additive primary colors of the visible spectrum, a first filter strip suppressing one of said primary colors, a second transparent strip substantially identical with said first transparent strip, and a second filter strip suppressing another of said primary colors; electronic reading means provided with sweep means for scanning said screen along lines transverse to said strips to produce an electrical output signal composed of luminance pulses from said transparent strips alternating with color-difference pulses from said filter strips, each of said pulses lasting for a predetermined period; distributor means synchronized with said sweep means and connected to said reading means for successively extracting said pulses frOm said output signal; storage means connected to said distributor means for delaying certain of said pulses to obtain coincidence between each color-difference pulse and an adjoining luminance pulse; subtractor means connected to said distributor means and said storage means for differentially combining the coincident color-difference and luminance pulses to produce chrominance pulse representing the suppressed primary colors of the respective color-difference pulses; adder means with input connections to said reading means and said substractor means for combining said chrominance pulses with complementary color-difference pulses to produce reconstituted luminance pulses during intervals between luminance pulses directly obtained from said output signal; and switch means connected to said adder means and said reading means for interleaving said directly obtained luminance pulses with said reconstituted luminance pulses.
Claim 2
Independent Claim
308 words
A system for generating luminance and color signals for the transmission of color-television images over an outgoing video channel, comprising: a photosensitive screen adapted to receive the projected image of an object; a mask interposed between said screen and the location of said object, said mask being subdivided into a multiplicity of parallel strips of different light transmissivity, said strips being divided into groups of four with an invariable sequence of a first transparent strip passing all three additive primary colors of the visible spectrum, a first filter strip suppressing one of said primary colors, a second transparent strip substantially identical with said first transparent strip, and a second filter strip suppressing another of said primary colors; electronic reading means provided with sweep means for scanning said screen along lines transverse to said strips to produce an electrical output signal composed of luminance pulses from said transparent strips alternating with color-difference pulses from said filter strips, each of said pulses lasting for a predetermined period; distributor means synchronized with said sweep means and connected to said reading means for successively extracting said pulses frOm said output signal; storage means connected to said distributor means for delaying certain of said pulses to obtain coincidence between each color-difference pulse and an adjoining luminance pulse; subtractor means connected to said distributor means and said storage means for differentially combining the coincident color-difference and luminance pulses to produce chrominance pulse representing the suppressed primary colors of the respective color-difference pulses; adder means with input connections to said reading means and said substractor means for combining said chrominance pulses with complementary color-difference pulses to produce reconstituted luminance pulses during intervals between luminance pulses directly obtained from said output signal; and switch means connected to said adder means and said reading means for interleaving said directly obtained luminance pulses with said reconstituted luminance pulses.
Claim 3
Dependent Claim
43 words
A system as defined in claim 1 wherein the delay of said storage means is of such magnitude that a given color-difference pulse fed jointly with a luminance pulse to said subtractor means reaches said adder means together with the resulting chrominance pulse.
Claim 4
Dependent Claim
39 words
A system as defined in claim 2 wherein said subtractor means is connected to receive said luminance pulses from said distributor means through said storage means with a delay enabling differential combination thereof with the immediately following color-difference pulse.
Claim 5
Dependent Claim
82 words
A system as defined in claim 3, further comprising monitoring means connected to said reading means for detecting the occurrence of a substantial amplitude change in said output signal, indicative of a color boundary in the projected image, and switchover means controlled by said monitoring means for temporarily modifying the connections from said distributor means and said storage means to said subtractor means for differentially combining a delayed color-difference pulse with an immediately following luminance pulse to produce the next chrominance pulse.
Claim 6
Dependent Claim
45 words
A system as defined in claim 4, further comprising a delay network with a delay equal to at least one pulse period inserted between said reading means and said distributor means, said monitoring means being connected to said reading means upstream of said delay network.
Claim 7
Dependent Claim
15 words
A system as defined in claim 1 wherein said filter strips are cyan and yellow.
Claim 8
Dependent Claim
42 words
A system as defined in claim 1, further comprising an output matrix connected to said switch means and said subtractor means for receiving said luminance and chrominance pulses and for deriving therefrom chrominance signals for the third one of said primary colors.
Claim 9
Dependent Claim
27 words
A system as defined in claim 7 wherein the connection between said substractor means and said output matrix includes low-pass filter means for integrating said chrominance pulses.
Claim 10
Dependent Claim
35 words
A system as defined in claim 8 wherein the connection between said switch means and said output matrix includes a storage network with a delay period substantially equaling the recurrence period of said chrominance pulses.
Claim 11
Dependent Claim
41 words
A system as defined in claim 1 wherein said sweep means comprises a deflection circuit, a high-frequency oscillator, phase-comparison means connected to said reading means and to said oscillator, and control means for said deflection circuit connected to said phase-comparison means.
Claim 12
Independent Claim
228 words
A method of generating luminance and color signals for the transmission of color-television images over an outgoing video channel, comprising the steps of: a. projecting the image of an object upon a photosensitive screen through a mask subdivided into a multiplicity of parallel strips of different light transmissivitiy, said strips being divided into groups of four with an invariable sequence of a first transparent strip passing all three additive primary colors of the visible spectrum, a first filter strip suppressing one of said primary colors, a second transparent strip substantially identical with said first transparEnt strip, and a second filter strip suppressing another of said primary colors; b. electronically scanning said screen along lines transverse to said strips to produce an electrical output signal composed of luminance pulses from said transparent strips alternating with color-difference pulses from said filter strips, each of said pulses lasting for a predetermined period; c. delaying certain of said pulses obtaining coincidence between each color-difference pulse and an adjoining luminance pulses; d. differentially combining the coincident color-difference and luminance pulses to produce chrominance pulses representing the suppressed primary colors of the respective color-difference pulses; e. additively combining said chrominance pulses with complementary color-difference pulses to produce reconstituted luminance pulses during intervals between luminance pulses directly obtained from said output signal; and f. interleaving said directly obtained luminance pulses with said reconstituted luminance pulses.
Claim 13
Independent Claim
228 words
A method of generating luminance and color signals for the transmission of color-television images over an outgoing video channel, comprising the steps of: a. projecting the image of an object upon a photosensitive screen through a mask subdivided into a multiplicity of parallel strips of different light transmissivitiy, said strips being divided into groups of four with an invariable sequence of a first transparent strip passing all three additive primary colors of the visible spectrum, a first filter strip suppressing one of said primary colors, a second transparent strip substantially identical with said first transparEnt strip, and a second filter strip suppressing another of said primary colors; b. electronically scanning said screen along lines transverse to said strips to produce an electrical output signal composed of luminance pulses from said transparent strips alternating with color-difference pulses from said filter strips, each of said pulses lasting for a predetermined period; c. delaying certain of said pulses obtaining coincidence between each color-difference pulse and an adjoining luminance pulses; d. differentially combining the coincident color-difference and luminance pulses to produce chrominance pulses representing the suppressed primary colors of the respective color-difference pulses; e. additively combining said chrominance pulses with complementary color-difference pulses to produce reconstituted luminance pulses during intervals between luminance pulses directly obtained from said output signal; and f. interleaving said directly obtained luminance pulses with said reconstituted luminance pulses.
Claim 14
Dependent Claim
31 words
A method as defined in claim 11 wherein said complementary color-difference pulses are the same from which the chrominance pulses combined therewith in step (e) have been derived in step (d).
Claim 15
Dependent Claim
34 words
A method as defined in claim 12 wherein said luminance pulses are delayed in step (c) for a sufficient time to enable their differential combination with the immediately following color-difference pulses in step (d).
Claim 16
Dependent Claim
61 words
A method as defined in claim 13, comprising the further step of (g) monitoring said output signal to detect the occurrence of a substantial amplitude change signifying a color boundary in the prejected image and, upon detecting such amplitude change, differentially combining in step (d) a delayed color-difference pulse with an immediately following luminance pulse to produce the next chrominance pulse.
Claim 17
Dependent Claim
36 words
A method as defined in claim 14 wherein the output signal is delayed, after the monitoring step (g), for at least on pulse period before extraction of said luminance and color-difference pulses therefrom in step (b).
Claim 18
Dependent Claim
19 words
A method as defined in claim 11 wherein the primary colors suppressed in step (a) are red and blue.
Claim 19
Dependent Claim
39 words
A method as defined in claim 11, comprising the further step of deriving chrominance signals for the third one of said primary colors from the chrominance pulses produced in step (d) and the interleaved luminance pulses of step (f).
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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) | 1978-11-17 | 1979-05-19 | 1979-11-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-11-17 | 1983-05-19 | 1983-11-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-11-17 | 1987-05-19 | 1987-11-18 | $7700.00 | Window Closed / Lapsed |