GB492035A - Improvements relating to sorting apparatus - Google Patents

Abstract

492,035. Photo-electric sorting apparatus. ELECTRIC SELECTORS, Ltd., and HORSFIELD, W. R. Feb. 9, 1938, No. 7017 /37. [Class 40 (iii)] Relates to photo-electric apparatus for scanning objects one at a time and sorting them in accordance with their albedo, colour, or transparency. According to the invention, the objects to be sorted are thrown one at a time across a free space and scanned by a photo-electric device while traversing that space, and the objects that are to be rejected are subjected to a jet of air which alters their trajectory. In the apparatus shown for sorting rice grains and other cereal grains, the grains are fed by the centrifugal apparatus described in Specification 492,037, [Group XXX], comprising a rotating disc, which throws off the grains in succession across a free space between a white background plate 12 and a mercury vapour lamp 14 in the form of a ring. The plate 12 is carried by a vertical rod 16 adjustably secured by a set-screw 18. The light reflected from the background plate and the grain is thrown on a photo-electric cell 28, an objective 20 being provided to focus the image of the grain on a slit 22, through which the light passes to the cell. The cell 28 is arranged in a casing 34 attached to another casing 44 containing an amplifier and mounted on the base plate of the apparatus. The slit 22 and the objective 20 are carried by a tube 26 adjustably secured to the casing 34 by a set-screw 36. The mercury vapour lamp 14 is in a casing 38 adjustably secured to the tube 26 by a set-screw 42. The bottom of the casing 38 is closed by a glass plate 54 and two half-plates 56, 58, one of which is slotted to form a passage 62 leading to a slot 64. A valve casing 74 is attached by tubes 72, 70 to the casing 38, and is fed with compressed air by a pipe 76. When a defective grain is scanned, the amplifier causes an electromagnet 82 to attract its armature 80 carrying a valve ball 78, which opens and allows a jet of air to issue at the slot 64. This slot is situated sufficiently away from the optical scanning axis to allow for the time lag of the apparatus, so that the defective grain is deflected downwards by this jet and falls in a hopper 88 by a trajectory 86, while the good grain follows a trajectory 82 and falls in a hopper 84. Grains accidentally deflected laterally miss a slit 92 in a baffle plate 90 and drop in a hopper 94, from which they are again supplied to the apparatus. The photo-electric device may be adapted to reject objects of wrong colour for example red or green objects from blue ones. The light may be thrown on the object from below as well as from above to cause ejection of unduly opaque objects.