Patent GB-272521-A (GB)
Title: Device for mechanically sorting natural and artificial products according to their colour and gradations of colour
IPC: B07C5/342
Filed: 1927-06-09
Abstract: 272,521. Weigl, A. June 9, 1926, [Convention date]. Light radiations, control of apparatus by; thermionic amplifiers.- Relates to apparatus for sorting coffee beans and other objects according to gradations of colour comprising a photo-electric cell in circuit with amplifying valves, the light reflected from a fixed area of the objects in succession being used to vary the current in the photoelectric circuit and to actuate corresponding electromagnets controlling the openings of a series of receptacles and consists in the means for feeding and presenting the articles in succession to the inspection device. The beans &c. are contained in a hopper 1, Fig. 1, which may be supplied by a main hopper, and is divided into two compartments 3a, 3<b> by an adjustable regulating plate 2, and are lifted from the forward compartment 3b in small quantities by a vertically-reciprocating cup 5 and presented to a nozzle 6 which is connected alternately to a suction pipe 7 for picking up one bean and to a compressed air pipe 8 for discharging it. The discharge is aided and the jet kept clear by a reciprocating pin 10 and the bean falls into a shoot 11 which is rocked to avoid the cup 5 in its upward movement. A hinged flap 14 holds the bean and is rocked to drop it into the rear compartment 18 of a cage 15, Fig. 1<b>, which has a central hinged and spring controlled flap 17 and is mounted in a fixed position over a reciprocating bar 13. The rear side of the cage is formed by a door which is reciprocated by a spring and detent connection 20 with the bar 13 to transfer the bean from the compartment 18 to the compartment 19 of the cage. Two centring jaws 24, 25, Fig. 2, take the bean from the compartment 19 and place it over a bar 21 from which it is raised and clamped under an aperture 23 in a fixed bar 22. In this position the bean is subjected to a beam of light from a lamp 35, Fig. 3, and the reflected light passed into the photo-electric cell 41 actuates one of the electromagnets 61, 66 &c. and opens the corresponding trap door 32 in a shoot 31. The bean is then released and discharged into the shoot by a blast of air from the pipe 30 and falls into the corresponding collecting shoot 34. The current induced in the photo-electric cell is amplified and used to operate a relay by which an electromagnetic circuit is opened. In the circuit shown in Fig. 3, the amplifying system comprises a two-grid thermionic valve 44, the filament 49 of which is heated by a battery 48. The grid 47 is .connected to the anode 46 of the photo-electric cell and to the negative side of the filament through a high resistance 50. The light-sensitive coating 40 of the cell is connected to the negative pole of a battery 45 of which the positive pole is connected to the negative pole of the battery 48. The anode 51 and the second grid 52 of the valve are connected in parallel in the circuit of a battery 53 and differentially energize the two coils 55, 56 of a re- Jay by which the current from a battery 62 is caused to energize one or other of the electromagnets 61, 66 &c. A contact 68 in the electromagnet circuit is opened after each exposure, and .during the setting of the relay contacts. In a modification, the amplifying valve is a three-electrode valve, the anode current being used to .operate a galvanometer, the arm of which moves over a succession of contacts.