Optoelectronic detector for a glass cullet sorter

A sorter of impurities, or colors, in glass cullet is a key device in waste-glass recycling plants. The arrangement of an optical sensor for a detector in the sorter, based on pairs of infrared LED and photodiode, is examined. The issues of tolerance of the optoelectronic components and their temperature dependence are resolved. The design of key electronic circuits of the detector is outlined. The main functions of the microcontroller firmware (multiplexing, ranging, impurity detection, filtering, detection of soiling, event timing), their solution and communication protocols are described. PC control software is briefly mentioned. The detectors work successfully in a Czech recycling plant.