GB340977A - Improvements in or relating to a manner of and machinery for the extraction of stalk from tea - Google Patents

Abstract

340,977. Separating solid materials. ABBOTT, T. E., and BURN, H. H., 28, Dalhousie Square, Calcutta, India. June 17, 1929, No. 18643. Convention date, May 10. Void [Published under Sect. 91 of the Acts]. [Class 117.] Apparatus for separating tea from stalk by utilizing the difference in colour comprises means for feeding the particles in succession to a position in which they are examined by a light-sensitive device which selectively operates mechanical separating means. In the construction described, a series of lightsensitive devices 5, Fig. 1, is arranged transversely above an endless conveyer 4 consisting of a corresponding number of rows of pivoted flaps 26, Fig. 7, each adapted to support a particle and retained in its normal position by a spring latch 30 having a depending lug 32. Beneath each row of flaps is mounted a pin 10 forming part of the armature of a solenoid and adapted to be moved by the current in the photo-electric circuit into the path of the latch 30 so as to release the corresponding flap and allow it to discharge its content into a chute 11. A series of loose discs 12 resets the flaps in their normal position. The feeding device consists of a hopper 1 mounted on spring arms 2 and oscillated by a crank and connecting-rod. An adjustable discharge slot permits the particles to fall in a thin sheet on an inclined plate 3 which may have ridges and grooves to arrange them in rows in alignment with the flaps. The lightsensitive device may be in the form of an evacuated tube 34, Fig. 8, with an inner coating of silver 35 over which is deposited a coating 36, one atom thick, of cµsium, rubidium, selenium, potassium, sodium or lithium, which is exposed at one end 37 by omitting the silver layer. Alternatively, a metal, preferably copper, plate 41, Fig. 9, is coated with selenium 42 covered with gold leaf 43 cut away at the centre. The current passing in the circuit of the light-sensitive device is preferably amplified by the use of transformers and thermionic valves, the output current being utilized to energize the solenoid actuating the pins 10.