The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
May. 13, 1986
Filed:
Nov. 28, 1983
John S Prince, Vestal, NY (US);
Harold L Herz, Binghamton, NY (US);
Edward P Coleman, Jr, Binghamton, NY (US);
General Electric Company, Binghamton, NY (US);
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.