Electro-optic barcode reader

摘要

An optical assembly and electronic reader circuit cooperate to provide a highly-efficient and low-cost electro-optic barcode reader. The optical assembly includes a shielded housing, a photo detector and optical elements disposed about an un-folded optical path that provide a virtual reading window at one end of the housing whose field of view, which is focused to a point at the photo detector, is shaped to be no wider than constitutive barcode indicia. The electronic reader circuit includes a pulse amplifier and manual-adjustment-free average D.C. offset negative feedback and A.C. information peak detect negative feedback loops that respectively maintain the electrical pulse stream input to the pulse amplifier within the dynamic range thereof and eliminate electrical pulse stream peak noise. A circuit is coupled to a comparator with hysteresis square-up stage to deactivate the comparator in the state of no input signal.