Method and device for sorting products

摘要

The invention concerns a method and apparatus for sorting a stream of products by scanning this stream of products with a bundle of concentrated light and analyzing the light originating from the scanned products and a background element, wherein this background element is chosen such that the corresponding detected light signal differs from the light signals originating from the products to be sorted in at least one parameter and wherein one or more control signals are generated by shifting the background level of the observed light signals to a signal level chosen such that, in the thus obtained signal, the signal level of the signal of a scanned product to be accepted distinguishes itself from the signal level of the signal of a scanned product to be rejected.

主权项

1. A method for sorting a product stream into products to be accepted and products to be rejected comprising:
moving the product stream through a scanning zone, with the product stream extending over a predetermined width W and having a thickness of substantially a single layer of products; linearly scanning across the width W of the product stream in the scanning zone with one or more concentrated light beams to illuminate the product stream and a background element positioned behind the product stream and extending over the width W, whereby the one or more concentrated light beams produce reflected light signals from scanned products and reflected light signals from the scanned background element, and wherein the background element is chosen such that the corresponding detected reflected light signal from the scanned background element differs in at least one parameter from the reflected light signals from both the scanned products to be accepted and the scanned products to be rejected; detecting the reflected light signals and converting the reflected light signals into electric signals; after detecting and converting the reflected light signals into electric signals, shifting a background level of the electric signals, wherein the background level is obtained from converting reflected light signals from the background element, to a new background level, to obtain a signal D, wherein said new background level is chosen such that an electrical signal level of the signal D corresponding to a scanned product to be accepted differs from an electrical signal level of the signal D corresponding to a scanned product to be rejected, and wherein the new background level is not identified as a product to be rejected; after shifting the background level of the electric signals, generating one or more control signals based on the electric signals whereby the control signals allow making a selection between the scanned products to be accepted and the scanned products to be rejected; and sorting the product stream using the one or more control signals.