Software controllable hardware CRT dimmer
AssigneeIntel Corporation
InventorGregory W. Ledenbach
Life of this patent
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Abstract
An apparatus for controlling a video display on a viewing screen such that it will not burn in the screen when the image is left unchanged for a prolonged period of time. A software controlled dimming circuit implements a shifting operation to the digital signal when activated. The shifting results in a lowering of intensity of the screen, yet retaining the original image on the screen.
Claims15
An apparatus for controlling a video display comprising:
- a memory for storing digital signals representative of video data;
- a dimming circuit coupled to receive an output from said memory, said dimming circuit passing said stored digital signals from said memory as first output digital signals representing a video image when a dimming function is not used and said dimming circuit converting said stored digital signals by shifting said stored digital signals a predetermined number of bit position, wherein said shifted stored digital signals provide second output digital signals representing a lower intensity image when said dimming function is used;
- a digital-to-analog converter (DAC) coupled to said dimming circuit for receiving and converting said output digital signals to analog video signals;
- control means coupled to control said memory, dimming circuit and DAC, and to activate said dimming function;
- whereby said video display shows said lower intensity image when said dimming function is activated.
An apparatus for controlling a display of a video viewing screen comprising:
- a memory for storing digital signals representative of video data and which control pixels of said display;
- addressing means coupled to said memory for accessing said memory;
- a dimming circuit coupled to receive an output from said memory, said dimming circuit passing said stored digital signals from said memory as first output digital signals representing a video image when a dimming function is not used and said dimming circuit converting said stored digital signals by shifting said stored digital signals a predetermined number of bit position wherein said shifted stored digital signals provide second output digital signals representing a lower intensity image when said dimming function is used;
- a plurality of digital-to-analog converters (DACs) coupled to said dimming circuit for receiving and converting said output digital signals to analog red-green-blue (R,G,B) video signals;
- control means coupled to control said memory, dimming circuit and DACs, for activating said dimming function of said dimming circuit;
- whereby said video display shows said lower intensity image on said screen when said dimming function is activated.
A method of providing a dimmed image to prevent permanent retention of such image on a video display screen, comprising the steps of:
- storing digital signals representative of a video image in a memory;
- accessing said stored digital signals for displaying said image;
- converting said stored digital signals to a lower binary weighted value by shifting bits to a lesser significant bit position a predetermined number of bit positions and padding vacated more significant bit positions with zeroes when dimming is desired;
- converting said digital signals to analog video signals;
- whereby lower intensity image represented by said analog video signals is displayed.
Dependencies are inferred from the claim text.