Abstract: Method and apparatus for sorting objects according to the degree to which they possess a required characteristic. Objects are moved in a line on a conveyor belt past a line of detectors each responsive to the required characteristic. Each detector produces a time sequence of output signals and the signals from successive detectors are accumulated. The objects are projected from the downstream end of the conveyor belt in a free flight path past an optical scanner and a series of air blast nozzles. The scanner determines the portions and sizes of the objects and objects selected on a comparison of the detector signals and signals from the scanner are blasted with air jets from appropriate nozzles so as to be deflected from their free flight trajectory. Deflected and undeflected objects are caught in separate collection bins.

Abstract: A tracking system for a sorting apparatus for sorting pieces of material moving through a sorting zone in a wide path random stream has a light scanning device which makes repeated scans across the sorting zone to detect light reflected from the pieces of material, and downstream of the scanning device a plurality of deflection devices extending across the sorting zone. An electronic control generates timing signals which, in effect, represent a plurality of overlapping analyzing channels extending in the direction of movement of the pieces of material and overlapping one another across the sorting zone. An electrical circuit arrangement for each analyzing channel receives signals from the scanning device and accumulates information relating to pieces of material in that channel and provides a decision signal based on the accumulated information.