Food sorting by reflection of periodically scanned laser beam

US5448363A · kind A · utility

Inventor

• Horst Hager · Paderborn, DE

Key dates

• Filing date: Aug 9, 1993
• Grant date: Sep 5, 1995
• Expiry date: Aug 9, 2013

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y10S209/908
• WIPO field: Chemical engineering
• WIPO sector: Chemistry

Abstract

In a machine for sorting food pieces such as potatoes the pieces are dropped one at a time through scanned laser beams that sequentially scan over its surface on all sides. Detectors measure laser light reflected from the food as the beam scans over the surface; variations indicate bad spots. To determine when the beam is not shining directly onto the food piece, a ribbon-like direct light detector is circumferentially deployed about the test zone. The reflected light is changed to electric signals and is analyzed by the microprocessor to decide if the food piece is to be deflected by an air jet. When the direct-light detector registers an un-interrupted laser beam, the microprocessor ignores the reflected light signals; that is, the direct light signal gates the reflected light signal. The reflected-light detector may be a bundle of up to 50 optical fibers having the fiber ends regularly disposed about the ring, so as to detect the light intensity at various evenly-spaced angles around the test zone. The direct-light detector may be a ribbon-like bundle of parallel fibers presenting an interior cylindrical surface. Each fiber is partially ground down on the back side so that laser…