Character reader with hand held scanner - contains light source and photodetector network responsive to reflected light

摘要

The character reader uses a hand-held scanner, which is moved across the document being read. This scanner has a light source, for directing light onto the zone of the document being scanned and a photodetector network, for detecting the light reflected by the document surface. The photodetector network is connected to a recognition circuit, providing a control signal, when no light is reflected back to the photodetector network, e.g. in the absence of the document. This control signal is supplied to a timing circuit, for reducing the excitation of the lamp, after a given interval, with the timing circuit re-set in response to an alteration in the control signal.