Facsimile and static presentation processing – Facsimile – Specific signal processing circuitry
Patent
1983-11-28
1986-05-13
Chin, Tommy P.
Facsimile and static presentation processing
Facsimile
Specific signal processing circuitry
358164, H04N 5202, H04N 558
Patent
active
045890226
ABSTRACT:
A video brightness control system for high performance CRT displays including a buffer amplifier for receiving high speed video information and applying it to a gain control variable resistor serving as a contrast control. An ambient light sensor drives a nonlinear amplifier to provide an ambient light signal which is in proportion to the logarithm of the ambient light level over a wide range. A manual brightness control potentiometer is adjustable to provide a constant brightness signal. The video information signal, the ambient light signal, and the manual brightness control signal are added together by a summing device, with the resultant signal approximating a logarithmic characteristic. The output of the summing device is applied to a gamma correction amplifier which drives a video driver amplifier, the video amplifier, in turn, drives the CRT. The gamma correction amplifier and video driver in combination with the video transfer function of the CRT approximates an exponential transfer function, thereby creating CRT screen brightness which is an antilogarithmic function of the total video signal appearing at the gamma correction amplifier input. This results in automatic brightness control as a function of ambient light level, minimum interaction between brightness and contrast controls, and a gamma characteristic which provides a reasonable approximation to the variation of brightness difference threshold of the eye.
REFERENCES:
patent: 4005262 (1977-01-01), Fijisawa
patent: 4415921 (1983-11-01), Mulvanny
Microelectronics-Digital and Analog Circuits and Systems, by J. Millman, McGraw-Hill Book Company, pp. 50-52, published 1979.
Variable Gamma Corrector Improves Television Video Signals, by K. Freeman, et al., Electronic Engineering, Sep. 1970, vol. 42, No. 511, pp. 90-93.
Coleman, Jr. Edward P.
Herz Harold L.
Prince John S.
Blumenfeld I. David
Chin Tommy P.
General Electric Company
LandOfFree
Brightness control system for CRT video display does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Brightness control system for CRT video display, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Brightness control system for CRT video display will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1773435