Patent US 3,944,979

A light source in an optical character recognition system is automatically controlled to operate at a plurality of light intensities. A relatively high light intensity is used to illuminate an object bearing indicia to be read. A relatively low light intensity is used at all other times. A plurality of detectors sense reflected or ambient light and produce output signals indicative of the intensity of the reflected or ambient light. First and second signals are generated to indicate whether the detector output is greater than or less than a predetermined threshold. The number of first and second signals generated in response to the outputs of the detectors are summed separately. If the number of first signals equals or exceeds a first predetermined number, the object is illuminated at a high light intensity. If the number of first signals is less than the first predetermined number, or if the number of second signals generated equals or exceeds a second predetermined number, the light source is switched to a low level light intensity.