US3647946A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Single-tube color tv camera using 120{20 {0 phase separation
Assignee: AT&T Inc
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Filing: 1969-12-10
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Granted: 1972-03-07
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Expires: 1989-12-10
Abstract
Abstract An optical system spatially modulates three individual primarycolor images onto a common spatial carrier frequency with 120* phase separation. Electron beam scanning of a single tube converts the spatially modulated image to an electrical output signal composed of an average value and a chrominance signal consisting of three modulated waves at a single electrical color carrier frequency separated in phase by 120*. Since the scan velocity varies, the frequency of the electrical color carrier is modulated by the velocity. A signal having the same modulation is used as a reference for phase demodulation of the chrominance signal to produce three individual components. The average value of the output signal, which represents the monochrome, is combined with each of the individual components to form three independent signals, each representative of one of the primary images. The phase demodulation technique requires substantially lower spatial resolution than time sequential or frequency separation schemes, and the specific 120* spatial phase separation of the image components insures against hue shift due to variations in the tube''s aperture response.
Inventors
- 👤 Louis H Enloe
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 11:08
CPC Classifications
H; H04; H04N; H04N9/00; H04N9/01
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
300 words
A color television camera cOmprising: optical means for focusing on a plane a composite image of a subject consisting of three primary color images superimposed and registered such that each of said primary images is spatially modulated onto a carrier at a common frequency, said carriers being mutually separated by a phase of 120 spatial degrees, means for passing light through a transparent periodic grating having a frequency below said common frequency to form a light pattern, means for superposing said light pattern on said composite image, a single electron beam pickup tube having a target in said plane and electron beam means for scanning said target to produce a signal consisting of a low-frequency component proportional to the monochrome of said composite image, a high-frequency component proportional to the chrominance of said composite image, said high-frequency component being composed of three modulated waves at a single carrier frequency with a mutual phase separation of 120 electrical degrees, and reference components derived from said superposed light pattern, each of said primary color images being focused on said plane by said optical means in a pattern of stripes so that at least one of said color stripes overlaps spatially with at least one other of said stripes, the area which is exclusively said one primary color being substantially narrower than the resolution capability of said electron beam means, means for generating from said reference components a reference signal which tracks the scan velocity of said electron beam, demodulation means for combining said reference signal with said high-frequency signal to separate said high-frequency component into three individual signals according to the phase differences among said individual signals, and means for algebraically combining each separated signal with said low-frequency component to produce three independent modulated outputs containing the color information of said subject.
Claim 2
Dependent Claim
300 words
A color television camera cOmprising: optical means for focusing on a plane a composite image of a subject consisting of three primary color images superimposed and registered such that each of said primary images is spatially modulated onto a carrier at a common frequency, said carriers being mutually separated by a phase of 120 spatial degrees, means for passing light through a transparent periodic grating having a frequency below said common frequency to form a light pattern, means for superposing said light pattern on said composite image, a single electron beam pickup tube having a target in said plane and electron beam means for scanning said target to produce a signal consisting of a low-frequency component proportional to the monochrome of said composite image, a high-frequency component proportional to the chrominance of said composite image, said high-frequency component being composed of three modulated waves at a single carrier frequency with a mutual phase separation of 120 electrical degrees, and reference components derived from said superposed light pattern, each of said primary color images being focused on said plane by said optical means in a pattern of stripes so that at least one of said color stripes overlaps spatially with at least one other of said stripes, the area which is exclusively said one primary color being substantially narrower than the resolution capability of said electron beam means, means for generating from said reference components a reference signal which tracks the scan velocity of said electron beam, demodulation means for combining said reference signal with said high-frequency signal to separate said high-frequency component into three individual signals according to the phase differences among said individual signals, and means for algebraically combining each separated signal with said low-frequency component to produce three independent modulated outputs containing the color information of said subject.
Claim 3
Dependent Claim
77 words
A color television camera as claimed in claim 1 wherein said optical means includes three primary dichroic mirrors positioned to split a subject image beam into three primary color images and a lenticular lens plate for focusing each of said primary color images on said plane in a pattern of primary color strip sets, said lenticular lens plate being positioned so that the image of said transparency is superimposed upon said plane with said three primary images.
Claim 4
Dependent Claim
91 words
A color television camera as claimed in claim 2 wherein said reference components produced by said scanning means consists of a component proportional to the frequency of said transparency and a component proportional to the frequency of the difference between the frequency of said lenticular lens and said transparency, and wherein said reference signal generating means includes means for separately passing said difference frequency component and said transparency frequency component and means for mixing said difference and said transparency frequency components to produce a sum frequency which is said reference signal.
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) | 1975-03-07 | 1975-09-06 | 1976-03-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-03-07 | 1979-09-06 | 1980-03-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-03-07 | 1983-09-06 | 1984-03-07 | $7700.00 | Window Closed / Lapsed |