A signal processing circuit of a bar code reader, includes a signal input unit for optically detecting a bar code provided on a surface of goods and outputting a first signal after optical-to-electrical conversion, a differential unit connected to the signal input unit, for amplifying and differentiating...http://www.google.de/patents/US5068520?utm_source=gb-gplus-sharePatent US5068520 - Signal processing circuit of a bar code reader
