What makes LCDs shine light

Unlike typical cathode ray displays that produce images on a screen by bombarding electrons into a layer of phosphorous, liquid crystal displays can’t actually produce their light while functioning. This is because the pixels on an LCD are basically like little shutters that vary their opacity accordingly to the amount of electric current they receive.

This disadvantage is especially visible in the case of old-fashioned monochrome liquid crystal displays, which can be read only when they are lit with light coming from the environment, and become totally useless in the absence of it. In this case, light coming from the Sun or reflected by the environment enters the LCD, passes through all the layers of the display before encountering a reflective surface that sends the light back to the viewer. Read more