The control system of LED normally by advocate accuse box, scanning board and show charge unit 3 major composition. Advocate the data of brightness of of all kinds that dominates box to get one screen to resemble element from inside the indication card of the computer, next reapportion gives a certain number of piece scanning board, a certain number of travel that every scanning board is in charge of controlling LED screen to go up (row) , and each (row) on of LED show accuse signal to be used serial means is deferent. Have the kind of signal of two kinds of serial and deferent indication control at present: One kind is the concentration on scanning board control resembles element to nod gray scale each, the resembles element all right each brightness value that scanning board will control box oneself undertakes decomposing (namely wide modulation of arteries and veins) , will go each next the enlightened signal of LED with pulse form (illume for 1, not bright for 0) by transmit corresponding LED to go up with serial means all right, control its to whether illume. Use parts of an apparatus of this kind of means is less, but serial transmission data bulk is greater, inside the cycle that because repeat in,illumes, every elephant element needs 16 pulse below 16 class gray scale, 256 pulse need below 256 class gray scale, because frequency of job of parts of an apparatus is restricted, can make LED screen accomplishs 16 class gray scale only commonly.
Another kind of method is scanning board serial the switch signal that transmission content is not every LED however a brightness value of 8 binary systems. Every LED has wide modulator of his arteries and veins to dominate bit of bright time. Such, illuming cycle repeats in inside, dot of every elephant element falls to need 4 pulse only in 16 class gray scale, 256 class gray scale falls to need 8 pulse only, reduced serial transmission frequency greatly. The method that controls LED gray scale dispersedly with this kind is OK very realize control of 256 class gray scale conveniently
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