GB699263A - Improvements in scanning head for color sorting apparatus - Google Patents

Abstract

699,263. Sorting photo-electrically. BICKLEY, E. H. May 7, 1951, No. 10700/51. Class 40 (iii). When sorting articles photo-electrically, those having only a small defective spot of a different colour from the rest of the article are detected by using two photo-cells in a normally balanced circuit, one responsive to the background colour and the other to the defect colour. The invention is described with reference to a system for rejecting peanut kernels which have a piece of skin adhering to them. As shown (Fig. 2), kernels are brought by a conveyer belt to a position immediately below the axis of a tube 11. There, light from a source (not shown) is reflected from the kernel and focused by lenses 21, 22 through an aperture in a mask 23. A second mask 24 cuts off stray light. After passing through mask 23 the beam strikes two photo-cells 14, 15 arranged side by side. Cell 14 is more sensitive to red rays, cell 15 to blue. The relative sensitivity of the two cells is determined by the position of a pivoted flap 31, polished on both sides and adjustable from outside the cell housing. The lamp is provided with a reflector and a shutter to adjust the total illumination. It is stated that the arrangement is applicable to control. ling the flow of liquid in transparent pipes. Circuit and operation (Fig. 3).-The red sensitive cell 14 is connected between the H.T. supply and grid of a triode 26 while the blue sensitive cell 15 is connected across the grid resistor 27 of the same tube. In the anode circuit is connected the primary coil 30 of transformer feeding a magnetic valve which controls a jet of air to eject defective kernels. The shutter is so adjusted that the presence of a piece of red skin operates the valve. Specification 615,996 is referred to.