Abstract: An integrated circuit is shown for use as a controller for a track sensor used with document processors. The track sensor includes a light source and a light detector. The circuit monitors the signal from the light sensing portion of the sensor, comparing the signal with a standard value and providing a feedback signal to the light source to adjust the intensity of the light to compensate for the effects of aging, holes in a document, the accumulation of dirt on sensor lenses and the like. The circuit determines when the leading edge of a document arrives and when the trailing edges pass by. It includes elements which prevent false indications that the trailing edge has passed when holes go by the sensor.

Abstract: A constant spacing document feeder employs a motor control circuit which drives a feed wheel at an average speed which is dependent upon the length of a document.Since the spacing between successive documents is a function of the length of each following document, by varying the speed of the feed wheel in accordance with the length of each document, the spacing between each document can be maintained substantially constant.

Abstract: A beam-of-light (BOL) sensor having means for regulating the intensity of the sensor light source to compensate for extraneous factors in its operating environment, e.g., dust accumulation, component aging, misalignment, etc., that may affect consistent sensor operation. The BOL sensor includes a photosensor whose output signal is compared against a reference signal to determine if the light source intensity is of the proper level. The comparison signal is used to gate clock pulses to a counter to adjust its stored count upward or downward, dependent on whether the light source intensity is low or high, respectively. A filter is provided to override interruptions in the photosensor output signal below a predetermined minimum time duration.

Abstract: A beam-of-light (BOL) sensor having means for regulating the intensity of the sensor light source to compensate for extraneous factors in the operating environment, e.g. dust accumulation, that may affect consistent sensor operation. The BOL sensor includes a photosensor whose output signal is compared against a reference signal to determine if the light source intensity is of the proper level. The comparison signal is transformed into a digital pulse that adjusts the stored count of a counter upward or downward in accordance with the comparison of the photosensor signal and reference signal. The adjusted count is converted to analog form and fed back to drive the light source.A trailing edge detector enables the counter to count up or down when an object is in the sensing station defined by the light source and photosensor.