Photodetector for use in reading optical information symbols

摘要

A bar code reader capable of working over a wider range of working angle and for a wider range of bar code densities, using improved optics and sensing elements. The optics and sensing elements and/or the associated circuitry are arranged to provide two channels of data derived from the scanned bar code. The two channels have differing resolutions. Analysis of the data from the two channels provides a single decoded result. As the working angle and density vary at least one of the resolutions will be appropriate for sensing all or most of the bar coded data. The data from the channel producing a valid result can be used, or if neither channel produces a valid result by itself, data from each channel can be analyzed and valid portions of the data from both channels combined to produce the single decoded result. The different resolution of the two channels can be provided using different size photodetection areas, e.g., small and large groups of active areas on a sensor array.