Software controllable hardware CRT dimmer
First Claim
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1. 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.
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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.
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Citations
15 Claims
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1. An apparatus for controlling a video display comprising:
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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. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. An apparatus for controlling a display of a video viewing screen comprising:
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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. - View Dependent Claims (9, 10, 11, 12, 13, 14)
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15. A method of providing a dimmed image to prevent permanent retention of such image on a video display screen, comprising the steps of:
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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.
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Specification