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Optical Scanner, a computer input device that uses light-sensing equipment to scan paper or another medium, translating the pattern of light and dark (or colour) into a digital signal that can be manipulated by either optical character recognition software or graphics software. A frequently encountered type of scanner is "flatbed", meaning that the scanning device moves across or reads across a stationary document. On a flatbed scanner such as the common office copier, objects are placed face down on a flat piece of glass and scanned by a mechanism that passes under them. Another type of flatbed scanner uses a scanning element placed in a stationary housing above the document.
Other scanners work by pulling in sheets of paper, which are scanned as they pass over a stationary scanning mechanism, as in the common office fax machine. Some specialized scanners work with a standard video camera, translating the video signal into a digital signal for processing by computer software.
A very popular type of scanner is the hand-held scanner, so called because the user holds the scanner in his or her hand and moves it over the document to be scanned. Hand-held scanners have the advantage of relatively low cost; however, they are somewhat limited by their inability to scan areas more than a few inches wide.
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