charge-coupled device

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charge-coupled device (CCD) Type of silicon chip designed to capture images. The CCD is divided into a number of microscopic areas (pixels), arranged in rows. When a photon hits a pixel, it knocks off an electron from a silicon atom, which becomes charged. An opposite charge in a layer on the base of the CCD confines this charged silicon atom, and in this way a charge builds up in each pixel relative to the number of photons hitting it 50 times a second. The contents of each pixel are read off, a row at a time, forming an electrical signal that can be used to create television pictures. CCDs are found in video cameras, fax machines, and digital cameras.

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