US4947253A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Brightness modulator for closed loop compensation of black level
Assignee: RCA Licensing Corp
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Filing: 1989-04-18
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Granted: 1990-08-07
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Expires: 2009-04-18
Abstract
Abstract A contrast control circuit 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 responsive to video signal peaks, a contrast limiter responsive to a beam current control signal related to average picture intensity and a manual control. A brightness modulator 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 for first and second video signals and a selector for alternatively feeding the first and second video signals to a video amplifier to form a primary picture with an inset secondary picture.
Inventors
- 👤 Charles B. Neal
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 02:27
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: 25
Claim 1
Independent Claim
131 words
A pix in pix video control circuit, comprising: first and second sources for video signals; a gain controllable video amplifier for the video signals; a video source selector for feeding the first and second video signals to the video amplifier to form a primary picture from one of the video sources with an inset secondary picture from the other of the video sources; means for developing a contrast control signal related to picture intensity; a contrast control circuit coupled to the video amplifier and responsive to the contrast control signal for developing a video gain control signal to adjust the contrast of the video signal by varying the gain; and, a brightness modulator responsive to the contrast control signal for adjusting the brightness of the video signal inversely with the contrast.
Claim 2
Dependent Claim
131 words
A pix in pix video control circuit, comprising: first and second sources for video signals; a gain controllable video amplifier for the video signals; a video source selector for feeding the first and second video signals to the video amplifier to form a primary picture from one of the video sources with an inset secondary picture from the other of the video sources; means for developing a contrast control signal related to picture intensity; a contrast control circuit coupled to the video amplifier and responsive to the contrast control signal for developing a video gain control signal to adjust the contrast of the video signal by varying the gain; and, a brightness modulator responsive to the contrast control signal for adjusting the brightness of the video signal inversely with the contrast.
Claim 3
Dependent Claim
14 words
The control circuit of claim 1, further comprising means for manually adjusting the brightness.
Claim 4
Dependent Claim
41 words
The control circuit of claim 1, wherein the means for developing the contrast control signal comprises: a first contrast control responsive primarily to variations in average picture intensity; and, a second contrast control responsive primarily to variations in peak picture intensity.
Claim 5
Dependent Claim
27 words
The control circuit of claim 3, wherein: the first contrast control is responsive to beam current; and, the second contrast control is responsive to the video signals.
Claim 6
Dependent Claim
24 words
The control circuit of claim 1, further comprising means for manually adjusting the contrast coupled to the contrast control circuit and the video amplifier.
Claim 7
Dependent Claim
122 words
A video control circuit, comprising: a gain controllable video amplifier for a video signal; means for developing a contrast control signal related to picture intensity; a contrast control circuit coupled to the video amplifier and responsive to the contrast control signal for developing a video gain control signal to adjust the contrast of the video signal by varying the gain; a brightness modulator responsive in a first range of beam current values to the contrast control signal for adjusting the brightness of the video signal inversely with the contrast; and, a brightness limiter responsive to a filtered beam current control signal in a second range of beam current operating values for reducing the brightness of the video signal to reduce beam current.
Claim 8
Dependent Claim
122 words
A video control circuit, comprising: a gain controllable video amplifier for a video signal; means for developing a contrast control signal related to picture intensity; a contrast control circuit coupled to the video amplifier and responsive to the contrast control signal for developing a video gain control signal to adjust the contrast of the video signal by varying the gain; a brightness modulator responsive in a first range of beam current values to the contrast control signal for adjusting the brightness of the video signal inversely with the contrast; and, a brightness limiter responsive to a filtered beam current control signal in a second range of beam current operating values for reducing the brightness of the video signal to reduce beam current.
Claim 9
Dependent Claim
14 words
The control circuit of claim 6, further comprising means for manually adjusting the brightness
Claim 10
Dependent Claim
20 words
The control circuit of claim 6, further comprising means for manually adjusting the contrast coupled to the contrast control circuit.
Claim 11
Dependent Claim
41 words
The control circuit of claim 6, wherein the means for developing the contrast control signal comprises: a first contrast control responsive primarily to variations in average picture intensity; and, a second contrast control responsive primarily to variations in peak picture intensity.
Claim 12
Dependent Claim
82 words
A video control circuit, comprising: a gain controllable video amplifier for a video signal; means for developing a contrast control signal related to picture intensity; a contrast control circuit coupled to the video amplifier and responsive to the contrast control signal for developing a video gain control signal to adjust the contrast of the video signal by varying the gain; and, a brightness modulator responsive to the contrast control signal for adjusting the brightness of the video signal inversely with the contrast.
Claim 13
Dependent Claim
82 words
A video control circuit, comprising: a gain controllable video amplifier for a video signal; means for developing a contrast control signal related to picture intensity; a contrast control circuit coupled to the video amplifier and responsive to the contrast control signal for developing a video gain control signal to adjust the contrast of the video signal by varying the gain; and, a brightness modulator responsive to the contrast control signal for adjusting the brightness of the video signal inversely with the contrast.
Claim 14
Dependent Claim
55 words
The control circuit of claim 10, further comprising: first and second sources for video signals; and, a video source selector for feeding the first and second video signals to the video amplifier to form a primary picture from one of the video sources with an inset secondary picture from the other of the video sources.
Claim 15
Dependent Claim
14 words
The control circuit of claim 10, further comprising: means for manually adjusting the brightness
Claim 16
Dependent Claim
18 words
The control circuit of claim 10, means for manually adjusting the contrast coupled to the contrast control circuit.
Claim 17
Dependent Claim
41 words
The control circuit of claim 10, wherein the means for developing the contrast control circuit comprises: a first contrast control responsive primarily to variations in average picture intensity; and, a second contrast control responsive primarily to variations in peak picture intensity.
Claim 18
Dependent Claim
53 words
A video control circuit, comprising: a gain controllable video amplifier for a video signal; means for developing a first control signal related to dynamic variations of picture intensity; and, a contrast and brightness control circuit responsive to the first control signal for simultaneously varying the contrast and brightness levels inversely with one another.
Claim 19
Dependent Claim
53 words
A video control circuit, comprising: a gain controllable video amplifier for a video signal; means for developing a first control signal related to dynamic variations of picture intensity; and, a contrast and brightness control circuit responsive to the first control signal for simultaneously varying the contrast and brightness levels inversely with one another.
Claim 20
Dependent Claim
41 words
The control circuit of claim 15, wherein the means for developing the contrast control signal comprises: a first contrast control responsive primarily to variations in average picture intensity; and, a second contrast control responsive primarily to variations in peak picture intensity.
Claim 21
Dependent Claim
43 words
The control circuit of claim 15, further comprising: means for developing a beam current control signal from which high frequency components have been removed; and, a brightness limiter responsive to the beam current control signal for reducing the brightness of the video signal.
Claim 22
Dependent Claim
63 words
The control circuit of claim 15, wherein the contrast and brightness control circuit comprises: a first circuit responsive to the first control signal for developing a video gain control signal for adjusting the contrast by varying the gain; and, a second circuit responsive to the contrast control signal for developing a brightness control voltage which varies inversely with the video gain control signal.
Claim 23
Dependent Claim
33 words
The control circuit of claim 15, wherein the contrast and brightness control circuit comprises means for developing first and second inversely related control voltages for adjusting the video gain and brightness level, respectively.
Claim 24
Dependent Claim
28 words
The control circuit of claim 16, wherein: the first contrast control is responsive to beam current levels; and, the second contrast control is responsive to the video signals.
Claim 25
Dependent Claim
23 words
The control circuit of claim 15, wherein the first control signal is related to dynamic variations of both average and peak picture intensity.
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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) | 1993-08-06 | 1994-02-05 | 1994-08-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-08-06 | 1998-02-05 | 1998-08-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-08-06 | 2002-02-05 | 2002-08-07 | $7700.00 | Window Closed / Lapsed |