GB932635A - Improvements in or relating to machines for sorting articles of different grades - Google Patents

Abstract

932,635. Photo-electric inspection devices P. L. DURAN. Jan. 15, 1962 [Jan. 14, 1961], No. 1473/62. Class 40 (3). [Also in Group XXX] A machine for the high-speed inspection and sorting of small objects such as coffee beans, comprises a drum 1 mounted for rotation about a horizontal axis 2 in the direction indicated by the arrow. Mounted on the drum are a plurality of article pick-up cups arranged in curvilinear rows 4 along the length of the drum and in radial planes 4<SP>1</SP> round the drum. Suction is applied through the drum interior to the cups to cause beans 6 to be picked up from a hopper 7. If the machine is starting up this is prevented, until the correct running speed is reached, by shoe 60. Another shoe 61 cuts off suction so that bean clusters drop back into the hopper and only single beans properly seated in the cups are carried on and are allowed to fall only when their cup reaches line 19 and suction is once more cut off by shoe 62. The beans then drop in sequence along a series of paths 18 to intercept a photo-electric inspection path 17 scanned by rotation of disc 11 around axis 12 at a speed related to the movement of the drum. The speed of movement and the arrangement of the pick-up cups are so arranged that each bean passes through the inspection path 17 as one of the disc arms 13, 14 is positioned to inspect it. Radiation from a lamp 27 is collimated and reflected by prism 30 to two-slit beam splitter 31. One of the beams passes to prism 25 and is directed back across the inspection path to reference background surface 20, the other is deflected by prism 26 and directed across the inspection path to reference surface 21. Both sides of the bean are thus inspected. Light reflected from the bean and the background surfaces is returned to prism 32 and then directed towards mirror 34 which allows blue wavelengths to pass to photo-cell 37 and reflects other colours, the green component is separated by another mirror and directed to cell 38 whilst a third cell 39 receives the remaining (red) component. The light 27 also illuminates a reference surface 44 and light reflected from this is similarly split into blue, green and red components directed to photo-cells 40, 41 and 42. Each pair of cells detecting components of the same colour are arranged in a bridge circuit and the amplified outputs of the three bridge circuits combined and applied through a distributer to energize the coil of the appropriate one of a series of deflector plates- 55 causing it to move to deflect the unsatisfactory bean into a reject bin when the signal received by any of the inspection path cells differs from that received by the corresponding reference cell. Units 20, 21 and 44 are fitted so that they can be readily changed for others with different characteristics when required. The areas viewed by the system may be sub-divided to assist in the detection of surface spots.