Box detector in barcode environment

Abstract

A system where boxes ( ) move along a conveyor belt and a bar code scanner reads bar codes ( ) on the boxes and detects the presence of a box (with or without a readable barcode), which facilitates establishing a box detector that detects the leading edge of a box. The bar code scanner has a scanning laser beam source ( ) that directs a scanning laser beam ( ) at the path of bar codes on the boxes, and a sensor ( ) that detects reflections of the laser beam, so the output from the sensor can be used by a bar code reader ( ) to read bar codes. Instead of setting up a separate box detector, the output from the laser reflection sensor is delivered to a container detecting circuit ( ) that uses the output of the laser reflection sensor to detect the leading edge of the box. The container detecting circuit detects a rapid increase in output from the sensor from a level ( ) obtained when no box is present to a level B commonly exceeded by an ordinary box surface, with the circuit constructed to avoid false detections resulting from black or brown bars elements interspersed with highly reflective space elements of a bar code.