How do flat-panel displays differ from traditional screens?

Flat-panel screens are different because they do not use the cathode-ray tube. Cathode-ray tube monitors-the monitors that are nearly omnipresent around the world-work by bombarding a phosphorescent screen with a ray of electrons. The electrons illuminate "phosphors" on the screen into the reds, greens, and blues that form the picture. In contrast, flat-panel displays use a grid of electrodes, crystals, or vinyl polymers to create the small dots that make up the picture. Flat-panel screens are not a new idea: LCD (short for liquid crystal display) watches and calculators going back decades have relied on crystal-based flat-panel displays. The newest flat-panel screens found on laptop computers use plasma display panels (or "PDPs"). They can be very wide-over a meter-but only a few centimeters thick. A PDP screen is made of a layer of picture elements in the three primary colors. Electrodes from a grid behind produce a charge that create ultraviolet rays. These rays illuminate the various picture elements and form the picture.

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