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LCD is a flat panel display technology commonly used in TVs and computer monitors. It is also used in screens for mobile devices, such as laptops, tablets, and smartphones.
LCD displays don’t just look different from bulky CRT (Cathode Ray Tube) monitors, the way they operate is significantly different as well. Instead of firing electrons at a glass screen, an LCD has a backlight that provides light source to individual pixels arranged in a rectangular grid. Each pixel has a RGB (Red, Green, and Blue) sub-pixel that can be turned on or off. When all of a pixel’s sub-pixels are turned off, it appears black.
When all the sub-pixels are turned on 100%, it appears white. By adjusting the individual levels of red, green, and blue light, millions of color combinations are obtained.
How LCDs are Constructed
An LCD screen includes a thin layer of liquid crystal material sandwiched between two electrodes on glass substrates, with two polarizers on each side. A polarizer is an optical filter that lets light waves of a specific polarization pass through while blocking light waves of other polarizations. The electrodes need to be transparent, so the most popular material is ITO (Indium Tin Oxide).
As LCD can’t emit light itself, normally a backlight is placed behind an LCD screen in order to be seen during the dark environment. The light sources for backlight can be LED (Light Emitting Diode) or CCFL (Cold Cathode Fluorescent Lamps). The LED backlight is most popular. Of course, if you like to have a color display, a layer of color filter can be made into an LCD cell. The color filter consists of RGB color. You can also add a touch panel in front of an LCD.
