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I'm having some trouble understanding how a color LCD display works. Kayvon mentioned the colors being filtered so that the resulting color is perceived as the full range of colors, but what is the mechanism for actually tuning the red, green, or blue light escaping the pixel?


The previous slide and the upper-left of this slide show how the screen is broken into red, green, and blue areas. The backlight is white (contains red, green, and blue wavelengths) but as it leaves the screen it is filtered to be either red, green, or blue depending on which color of pigment dispersion fluid it passed through (see the upper-left of this slide). Now we need to actually "tune" the amount of each color escaping in order to represent different colors. This is shown in the bottom-right of this slide: in the on state all the light from the backlight escapes, so that spot on the screen is bright, and in the off state it's completely dark (it can also be in-between to make the screen dim). Notice in the upper-left of this slide that each color in the pixel has its own liquid crystals below, so we have individual control of exactly how bright each color should be. Since we can individually tune the amount of red, green, and blue in each pixel we can represent the full range of colors that humans can perceive.