DEEP FIELD OPTICAL LABEL READER INCLUDING MEANS FOR CERTIFYING THE VALIDITY OF A LABEL READING

摘要

A label reader includes a rotating faceted mirror which scans a beam from a low power gas laser repetitively across a conveyor. The beam path is within the viewing angle of a phototransducer. A package having a specially marked label thereon which passes through the beam excites the phototransducer in response to the label markings. The light received by the photosensor will thus be modulated in accordance with the label markings as scanned. The output of the phototransducer is thus a pulse train which is analyzed in a logic circuit to determine first that a label is being read and second to determine the validity of informational content on the label. Extreme depth of the reader field is provided by the laser which provides a coherent non-dispersive light source and additionally by a sensor which detects the distance of the label being read from the label reader and modifies the logic circuitry in accordance therewith.