Digitizer for a bar code reader utilizing a first derivative signal and an analog ground comparison signal

摘要

A system for digitizing an analog electric signal generated from the photoelectronic conversion of reflected light when scanning indicia having spatially-separated, light-reflective portions, the system including a differentiator circuit for generating a first derivative signal representing a first derivative of the analog signal. An analog ground comparison circuit compares the first derivative signal and an analog ground comparison signal to generate an output signal indicating a change in the intensity of the reflected light. An output circuit generates a digital output signal corresponding to the digital signal.