Method and apparatus for sorting materials using electromagnetic sensing

Abstract

An automated interrupt driven system which employs a circular buffer is used to sort materials based on differing electromagnetic radiation absorption and penetration characteristics. The system has a conveyor and a source of electromagnetic radiation which radiates materials travelling along the conveyor. A controller samples detector outputs at various times to evaluate the absorption and penetration characteristics of the materials to be sorted, based on a plurality of samples. Portions of the materials are ignored to obtain accurate readings from the detectors. Based on the detected penetration and absorption characteristics, the controller activates ejection mechanisms causing materials of different compositions to be deposited into different bins. The controller executes interrupts to cause detection, ejection, testing, and system history maintenance at required times. The circular buffer contains indices which point to various locations which are programmed in memory to trigger and perform specific events. The location of the indices in the circular buffer is used to control event timing, such as activating and deactivating the ejection mechanisms. This configuration, allows several events to be executed simultaneously by moving to the next location in the circular buffer while the event indicated by the index in the previous location continues in progress.

Description

The disclosed invention classifies materials by utilizing the tendency of penetrating electromagnetic radiation to pass through differing materials with differing levels of attenuation within the materials according to their chemical properties. The invention provides for separation of the differing materials from each other according to the amount of radiation passing through them. More specifically, penetrating electromagnetic radiation is used to simultaneously scan multiple material items as they pass through a region of radiation. Analysis of the measured radiation passed through differing portions of the body of each item is used to classify each item and activate means for separating from each other items which have differing chemical properties.It is well known that for materials having similar thicknesses, those materials comprised of elements having a lesser atomic number generally allow a greater degree of penetrating electromagnetic radiation to pass through them then do...

AI Technical Summary

Benefits of technology

It has been found that the disclosed invention surmounts the above mentioned limitations and provides efficient high volume separations by allowing plastic materials to be fed multiply and in a continuous manner without regard to orientation into a common region of penetrating electromagnetic radiation. Simultaneous measurements are made on all items as they move through the region of radiation, in order to distinguish and classify each plastic

Problems solved by technology

Accordingly, placement of an item between a radiation source and a radiation detector, such that radiation passing through only a relatively thin cross section is measured, requires sophisticated and expensive materials handling means.

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