Importance

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Abstract

An optical scanning system is provided for producing a signal representative of a spatial distribution of indicia having different degrees of reflectivity to light, such as a bar code. The system includes an optical scanner for scanning beam of light over the spatial distribution of indicia and for producing an electrical signal corresponding to changes in the degree of reflectivity of the indicia. A digitizer, responsive to detections in a predetermined characteristic of the produced electrical signal is provided. The digitizer converts the detections into digital words, such digital signals having a plurality of bits. The digitizer includes a timing generation circuit for producing a pulse in response to each one of the detections with a time duration representative of the degree of reflectivity of the indicia as the beam of light. A decoder converts the time duration of the pulse into the digital word having a plurality of bits. An enhancement filter is also disclosed. The enhancement filter modifies pulses produced by a differentiator circuit used in the scanner. Such modification includes increasing the rise time, and peak level of, the pulses produced by the differentiator circuit 24.

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First Claim