OPTICAL INSPECTION SYSTEM

摘要

In an optical inspection system for edible natural products, the products are passed through an inspection region in which light is directed onto the products from optical units (61 and 62) during passage of the products through the inspection region. A sensor (66, 67) detects light returned from the products passing through the inspection region. The invention provides an optical system consisting of lenses (84, 85, 86) for directing light from source units (61, 62) onto the products passing through the inspection region substantially at a specified target region (69) within the inspection region. The light sources (61, 62) comprise light emitting diodes (81, 82, 83) and the focussing is achieved by outer rows of diodes (82, 83) being displaced outwardly relative to the axes of respective cylindrical lenses (84, 85) of the optical system so that light originating from the outer rows of diodes (82, 83) converges towards that passing along the central axis (68) extending from a central row of diodes (81) through central lens (86) to the target region (69), light from all three rows of diodes (81, 82, 83) being therefore focussed substantially at the target region (69). Suitably the system comprises two lens assemblies (61, 62) working in association with a centrally located sensor assembly (66, 67). Advantages are reduction in the number of LEDs required at an inspection station, reduction of dirt build-up on sensor window (71) by virture of the target region (69) being located at a greater spacing than in constructions using unfocussed light, and substantial elimination of responsiveness to spurious signals originating beyond the target zone (69).