English Dictionary

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English Dictionary

light pen



  1. (computing)
    1. a rodlike device which, when applied to the screen of a cathode-ray tube, can detect the time of passage of the illuminated spot across that point thus enabling a computer to determine the position on the screen being pointed at
    2. a penlike device, used to read bar codes, that emits light and determines the intensity of that light as reflected from a small area of an adjacent surface


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