Edge effect compensating bar code reader

摘要

Apparatus and method for reading a luminescent bar code on a background surface whose reflectance may vary over the coded area, including a light source for providing light to scan, and to excite luminescence in the bar code or to reflect from the background surface of the coded area; a first detector responsive to reflected non-luminescent light for providing a first signal; a second detector responsive to luminescent light for providing a second signal; and memory having stored calibration indicia of reflectance and luminescence, the memory responsive to the first and second signals for providing an output signal substantially independent of background reflectance, and substantially free of bar code edge distortion.