From the name it may sound like LED display is made with LED diods and uses them to show image. LED display isn't exactly the best name for this kind of display. LED displays work based on LCD technology but use LED light for backlight. The LED light are on if display is on. The color is shown by pixels, very small tri-color plates in display that allow only so much Red, Green and Blue light that it will make desired color. There are liquid crystals behind these pixels that either allow light to pass or not. If you have black color on your display its is probably created not by allowing no light through pixels but by not allowing any light through liquid crystal. If you want to know more about this topic I suggest you to go to You Tube and find video about LCD monitor teardown. There are some LED displays created only by LED diods but these are used only for big screens on stadiums and squares. These displays, however, have very poor quality and that is intentional. If those were in some Full HD quality people wouldn't buy their own TVs and therefore big companies wouldn't earn enough money.