Patent GB-881161-A (GB)
Title: Method of and apparatus for sorting articles
IPC: B07C5/342
Filed: 1959-05-04
Abstract: 881,161. Photo-electric sorting apparatus. FOOD MACHINERY & CHEMICAL CORPORATION. May 4, 1959 [May 5, 1958], No. 15152/59. Class 40(3). A sorting apparatus comprises means for distributing articles in a number of paths, the paths being arranged in an annular inspection zone, means for receiving light reflected from the. articles in said paths and means, actuated by the receiving means, for sorting the articles in accordance with their light reflecting properties. In a first embodiment, Fig. 1, grains of rice pass from an annular hopper 11 to a multi-channel shoot 15. Unless deflected each grain falls along path b. A bank of lamps 38, together with reflecting and diffusing surfaces, ensures that the full surface of each grain is illuminated as it falls through the inspection zone A. It is arranged that only one grain from each  channel is in the inspection zone at any time  and during its fall through this zone each grain is inspected by a photo-cell 68 mounted in a rotary inspecting device 50. Light reflected from a rice grain passes to the cell  68 via the lens and mirror optical system of the device, which includes a slit 65 so that only one grain can be viewed at a time. The output of photocell 68 is amplified and an output which corresponds to a dirty rice  grain triggers a pulse generator 82, Fig. 4. The resultant pulse causes discharge at the end of a brush 83, Figs. 1 and 4, which is rotated with the inspection device 50, and passes to a segment of a spark commutator 110. This fires a trigger tube 115 which causes a relay to operate a valve 118 to pass an air jet into zone A thus deflecting the dirty grain along path c. A commutator segment and an associated trigger tube and valve are provided for each channel. The inspection device 50 is rotated by a motor 58 and rotates once in the time taken for a grain to pass through the inspection zone. A colour filter 67 may be provided in the device 50. In a second embodiment, Fig. 5 (not shown), light reflected from the rice grain is passed to two photo-cells which respond to different parts of the spectrum. When a clean grain is viewed by the inspection device the outputs of the two photocells, 201, 202, Fig. 7, are balanced but when a dirty grain is inspected the outputs are unequal. A comparator circuit, comprising valve 229, triggers a multivibrator 250 when the photocell outputs are unequal. The multivibrator is reset on conduction of a  photo-tube 262 of a synchronizer unit which comprises a disc mounted on the motor shaft of the sorting machine, Figs. 5 and 6 (not shown). The disc has a number of peripheral holes, a light shining through these holes on to the photo-tube. When the photo-tube 262 conducts, the brush 83 and the commutator segment 114 associated within the channel from which the dirty grain has fallen are adjacent and the multivibrator triggers the pulse generator 270. The latter pulses and charges in turn the brush 83 and the associated commutator segment 114, and a trigger tube 115 conducts causing a pneumatic valve to be opened and a jet of air to blow the dirty grain into the correct path. The conducting tube is extinguished by means of a transformer 283 and three phase bower source. In yet a further embodiment, Fig. 8 (not shown), the bank of lamps 38, Fig. 1, is replaced by a single lamp mounted on the axis of rotation of the inspection device. At the top of the inspection device is a mirror and lens system so that a beam of light is projected into the inspection zone, the beam rotating with the device. In this case the brush and commutator are mounted beneath the casing of the apparatus instead of, as in Fig. 1, under the multi-channel shoot.