Patent GB-950653-A (GB)
Title: Improvements in or relating to apparatus for checking and sorting sheet material
Inventor: THOMPSON JACK EVANS
IPC: G01N21/89
Filed: 1960-02-16
Abstract: 950,653. Sheet-delivery apparatus. SIMMONS & THOMPSON (AUTOMATION) Ltd., and R. D. H. THOMPSON & CO. Ltd. Feb. 16, 1961 [Feb 16, 1960], No. 5521/60. Heading B6H. [Also in Division G1] Sheets of material are examined and sorted by means of a photo-electric scanning unit which scans the sheets by reflected light as they pass over a surface of a colour which the scanning unit can distinguish from the sheet material, and a faulty sheet having for example a hole, or a dark-patch is rejected by means operated by a signal generated in the scanning unit in response to a flaw in the sheet material. For a sheet of a light colour, the surface is preferably black, and vice versa for dark or black sheets, and in each respective case, e.g. a hole or a dark patch in a white sheet, is similarly detected. The above scanning unit is supplemented by two further photo-electric scanning units which examine the thicknesses and surface gloss of the sheets. In the system shown in Fig. 1, sheets 5 of paper are fed by an oscillating suction device 10, 11 to a fixed metal platform by a conveyer member comprising spaced chains 1 driven by two pairs of sprockets 2 and carrying laterally disposed gripping members 4 spaced along the chains. The right-hand sprockets 2 are driven by a motor 8 and the shaft 3 of the left-hand sprockets is driven through gearing and a lay shaft, indicated at 49 in Fig. 2. Surface gloss is examined by a light source 23 and a photo-cell 24 connected to a comparator unit 25 which also receives the output from a photo-cell 29 of an auxiliary scanning unit having a light source 28 incident on a sheet 27 of normal gloss on a drum 26, the sheet 27 being of a size identical with a sheet 5, and the drum speed being such that the sheets 5, 27 are scanned simultaneously. For a faulty surface the output of the comparator 25 is fed to a memory unit 30 which also receives a signal from the photo-cell 34 illuminated by a source 33, if the sheet thickness is incorrect. A hole or patch of faulty (dark) colour is detected by a scanning unit 35 as a sheet 5 is traversed past a beam from a light source 36 by a rotating drum 9 carrying a sheet 15 of dark or black material retained on the drum by a rod 16 located in an axial slot 14 and tension springs 17. A flaw detected by the unit 35 also provides a signal for the memory device 30. Sorting and sheet-delivery arrangements.- Sheets 5 having imperfectness detected by any of the units 22, 32 or 35 are fed to a reject hopper 18, whilst acceptable sheets are deposited in small batches, e.g. of 10 sheets, alternately in two hoppers 19 and 20, each of the hoppers being provided with a base member 40 supported by chains 41 looped around pulleys 42 and linked to a driving motor for each hopper, and each base 40 carries a detachable stillage 43 supported on legs 44. The forward sides of the hoppers carry a mechanism for guiding and facilitating the passage of the rear end of a sheet into its hopper and comprises jogger members 48, Fig. 2, carried on screw-threaded shafts 54, 60 mounted in carriages 52, 62 supported on shafts 51, 51A and having gear-wheels 56, 58 on a telescopic shaft 57 engaging gears 55, 59 on the threaded shafts. The normal positions of the joggers 48 can be adjusted according to the width of the sheets, and during operation they are oscillated in the width direction of the sheet by eccentric cams 50, 50A on the layshaft 49. A sheet is released from its gripping member 4 for deposition in a hopper when its leading edge is approaching a rake member 45, adjustably positioned in accordance with the length of the sheets 5, by operation of a solenoid 90, Fig. 3, which actuates a toggle mechanism 92, 93 to the position shown in full lines in which an arm 95 engages a roller 100 on an arm 79 pivoted on the base 97 of the gripper member 4 to rock a spring biased flap 98 to release the sheet. Suction applied from a pipe 46, Fig. 1, underlying the rake 45 draws the landing edge of the sheet downwardly, and simultaneously with the operation of the solenoid 90, the rocking of a shaft 68, Fig. 2, engages the trailing edge of the sheet between rubber rollers 70 and metal rollers 67 to position the sheet to fall into its associated hopper. Suction units 66 also assist the arrest of the trailing edge to allow the sheet to fall into the hopper. The passage of the acceptable sheets to the hoppers 19, 20 is controlled by a light source 83 and photo-cell 84 detecting the leading edges of the sheets and passing pulses to a memory and counting device 85 controlling the electromagnets 90 associated with the hoppers 19, 20. In a preferable arrangement, a number of sheets e.g. 10 are deposited in the hopper 19 followed by a like number in the hopper 20. An air-brush comprising pulleys 80, Fig. 1, and a chain 81 carrying tubes 82 to which air is supplied under pressure can be associated with each of the hoppers 19 and 20, and the operation can be controlled from the memorycounting device 85 so that, for example, after five sheets have been fed to hopper 19, the airbrush associated with hopper 20 is operated until a total of ten sheets have been fed to the hopper 19. Sheets are then fed to hopper 20, and after five sheets have been deposited the air-brush associated with hopper 19 is operated until a further five sheets have been fed to the hopper 20. The counting device 85 may operate to insert tags into the respective piles of sheets in the hoppers when each has received, for example, five hundred sheets. The base plate 40 and stillage 43 may be lowered in steps as sheets are fed into the hoppers 19, 20 under control of a light-source 75 and photo-cell 76 which operates when light is reflected from edges of the sheets at the top of the hopper to actuate a switch 77 controlling a motor to lower the base 40. A similar control may, if necessary, be added to the reject hopper. In a modification, Fig. 4 (not shown), the sheets after leaving the drum 9 may be examined by units similar to the units 32 and 35, also associated with the memory 30, before they approach the reject hopper 18. The circuit 30 may be arranged so that it does not operate unless a predetermined minimum number of faults has been detected by the detector units 22, 32 and 35 individually or in combination. Alternatively, the signals from the detector units may be applied to an oscilloscope having an adjustable hair line or mark so that flaws giving rise to small output from the respective photo-cells do not operate the reject mechanism.