Patent EP0393946A2 successfully refreshed from Google Patents.
EP0393946A2
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EP
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Video control circuit
Assignee: Technicolor USA Inc
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Filing: 1990-04-12
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Granted: —
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Expires: 2010-04-12
Abstract
Abstract A contrast control circuit (54) develops a video gain control signal for continuously varying the video gain of a video signal to adjust the contrast of the video signal and limit beam current. The contrast control circuit may comprise an auto contrast control (24) responsive to video signal peaks, a contrast limiter (70) responsive to a beam current control signal related to average picture intensity and a manual control (20). A brightness modulator (72) is also responsive to the contrast control signal for continuously adjusting the brightness of the video signal inversely with the contrast. The brightness modulation is especially useful as part of a pix-in-pix video control circuit, further comprising video sources (30, 32) for first and second video signals and a selector (34) for alternatively feeding the first and second video signals to a video amplifier (52) to form a primary picture with an inset secondary picture.
Inventors
- 👤 Charles Bailey Neal
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-09 19:31
CPC Classifications
H; H04; H04N; H04N9/00; H04N9/12; H04N9/16; H04N9/18; H04N5/00; H04N5/44; H04N5/445; H04N5/45; H04N5/57
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
119 words
A video control circuit, comprising: a circuit path having an input for receiving a video input signal and shaving an output for providing a processed video output signal; a gain controllable video amplifier (52) in said circuit path; and circuit means coupled to said path and responsive to a signal manifestation of said processed video output signal for developing a picture control signal related to dynamic variations of picture intensity represented by said signal manifestation; characterized in that : said circuit means comprises a contrast and brightness control circuit (54,56,72) coupled to said path and responsive to said picture control signal for simultaneously varying the contrast and brightness levels of said processed video output signal inversely with one another.
Claim 2
Dependent Claim
119 words
A video control circuit, comprising: a circuit path having an input for receiving a video input signal and shaving an output for providing a processed video output signal; a gain controllable video amplifier (52) in said circuit path; and circuit means coupled to said path and responsive to a signal manifestation of said processed video output signal for developing a picture control signal related to dynamic variations of picture intensity represented by said signal manifestation; characterized in that : said circuit means comprises a contrast and brightness control circuit (54,56,72) coupled to said path and responsive to said picture control signal for simultaneously varying the contrast and brightness levels of said processed video output signal inversely with one another.
Claim 3
Dependent Claim
60 words
The control circuit as recited in Claim 1 further characterized in that said contrast and brightness control circuit comprises: means (54, 72) responsive to said picture control signal for developing first and second inversely related control voltages for adjusting the video gain and brightness level, respectively, of said processed video output signal supplied to said output of said circuit path.
Claim 4
Dependent Claim
89 words
The control circuit as recited in Claim 1 further characterized in that said contrast and brightness control circuit comprises: a first circuit (54) responsive to said picture control signal for developing a video gain control signal for adjusting the contrast of said processed video output signal by varying the gain of said amplifier; and a second circuit (72) responsive to said picture control signal for 30 developing a brightness control voltage which varies inversely with said contrast control signal for varying the brightness of said processed video output signal.
Claim 5
Dependent Claim
91 words
The control circuit as recited in Claim 1 further characterized in that said contrast and brightness control circuit comprises: a contrast control circuit (54) coupled to said video amplifier (52) and responsive to said picture control signal for developing a video gain control signal to adjust the contrast of said processed video output signal by varying the gain of said video amplifier; and a brightness modulator (72) responsive to said picture control signal for adjusting the brightness of said processed video output signal inversely with changes in said contrast control signal.
Claim 6
Dependent Claim
131 words
The control circuit as recited in Claim 1 further characterized in that said contrast and brightness control circuit comprises: a contrast control circuit (54) coupled to said video amplifier and responsive to said picture control signal for developing a contrast control signal to adjust the contrast of said processed video output signal by varying the gain of said amplifier; a brightness modulator (72) responsive in a first range of beam current values of said picture control signal for adjusting the brightness of said video output signal inversely with changes in said contrast control signal; and a brightness limiter (74) responsive to a filtered (76) beam current control signal in a second range of beam current operating values for reducing the brightness of said video output signal to reduce said beam current.
Claim 7
Dependent Claim
56 words
The control circuit as recited in Claim 1 further characterized in that said contrast and brightness control circuit includes means for developing a contrast control signal comprising: a first contrast control (18, 70, 54) responsive primarily to variations in average picture intensity; and a second contrast control (24,54) responsive primarily to variations in peak picture intensity.
Claim 8
Dependent Claim
50 words
The control circuit as recited in Claim 6 further characterized in that said first contrast control (18) is responsive to beam current levels of a display device to which said processed video output signal is appliced and said second contrast control (24) is responsive to said processed video output signal.
Claim 9
Dependent Claim
58 words
The control circuit as recited in Claim 1 further characterized by: means (76) for developing a beam current control signal from which high frequency components have been removed; and a brightness limiter (74) coupled to said contrast and brightness control circuit and responsive to the beam current control signal for reducing the brightness of said video output signal.
Claim 10
Dependent Claim
77 words
The control circuit as recited in Claim 1 further characterized by: first (30) and second (32) sources for video signals; and a video source selector (34) for selectively applying first and second video signals provided by said sources to said input of said circuit path so that said processed video output signal is representative of a primary picture from one of the video sources with an inset secondary 20 picture from the other of the video sources.
Claim 11
Dependent Claim
28 words
The control circuit as recited in Claim 1 further characterized in that: said picture control signal is related to dynamic variations of both average and peak picture intensity.
References Cited (Backward Citations)
No citation records indexed.
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