Classifying – separating – and assorting solids – Sorting special items – and certain methods and apparatus for... – Condition responsive means controls separating means
Patent
1988-07-12
1990-03-20
Hajec, Donald T.
Classifying, separating, and assorting solids
Sorting special items, and certain methods and apparatus for...
Condition responsive means controls separating means
209587, 209639, 209939, B07C 500
Patent
active
049099302
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
This invention relates to a foreign object separator including a multi zone detection system, and means for providing a fluid blast controlled by said detection system to remove foreign objects from a single flowing stream of material. In a known apparatus one of a series of fluid valves allocated to a number of detection zones may be operated on detection of a foreign particle. By appropriate timing the valve is actuated at the moment the particle arrives opposite an air blast nozzle connected to the valve.
A problem arises where an object which may be as large as a tag or label, extends beyond a single detection zone since due to the fall-off of air velocity at the zone edges the blast may be insufficient to remove the object. It is known that zone overlap can be provided by mechanical means, but with this fixed overlap a system cannot be easily optimised.
SUMMARY OF THE INVENTION
An object of the invention is to provide an apparatus in which the detection zones may be programmed so that each may overlap an adjacent zone. Furthermore, the zone positions, zone sizes and the extent of overlap may be determined.
According to the invention there is provided a foreign object separation apparatus comprising a feed conveyor for delivering material to be processed to an inspection region where the material descends, means for illuminating the material in the inspection region, a plurality of fluid blast nozzles, a plurality of solenoid controlled valves connected respectively to said nozzles, a camera for scanning the material descending in the inspection region, a background compensation and video comparator connected to said camera to receive pixel data therefrom, a reject position decoder for receiving reject data from the comparator, a programmable zone boundary decoder, the outputs of said reject position decoder and said boundary decoder being synchronized by clock signals outputed by said camera, and a zone decoder logic circuit connected to the outputs of said reject position decoder and said boundary decoder to produce outputs signals which actuate said solenoid controlled valves, said zone decoder logic circuit being programmable so that when a reject data signal from said comparator representing a position falling wholly within a main zone but outside an overlap zone is decoded in the zone decoder logic circuit the corresponding valve only will be actuated, whereas when a reject data signal from said comparator representing a position falling wholly or partly within a main zone and also wholly or partly within an overlap zone is decoded in the zone decoder logic, the valves controlling the nozzle on each side of the reject position will be actuated.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will now be described by way of example with reference to the accompanying drawing in which:
FIG. 1 is a perspective view of the apparatus with the cover broken away,
FIG. 2 is a block diagram of the apparatus,
FIG. 3 is a circuit of a background compensation and video comparator, and
FIG. 4 is a schematic diagram showing main zones and overlap zones covered by the camera.
DESCRIPTION OF THE PREFERRED EMBODIMENT
The separator system of the present invention comprises an optical pneumatic system comprising a feed conveyor 8 for delivering tobacco to an inspection region 9 where the tobacco descends, lamps 10, 11 which provide a high level of illumination (13,000 LUX), a 1024 element solid state camera 12, a control interface cubicle 13, and a solenoid operated pneumatic reject assembly shown generally at 14.
The camera view is separated electronically into eight main (1-8) zones and seven overlap zones (9-15), each main zone being 128 mm wide, and each overlap zone being 42 mm wide (see FIG. 4).
In operation the camera views a horizontal strip 1 mm by 1 meter, this view is converted by a lens, filter, and CCD assembly into a quantity of electrical charge. The quantity of charge is proportional to the reflectance of the object in view, and its spectral position, the charge
REFERENCES:
patent: 3472375 (1969-10-01), Mathews
patent: 3581888 (1971-06-01), Kelly
patent: 3977526 (1976-08-01), Gordon et al.
patent: 4352430 (1982-10-01), Maier et al.
patent: 4561545 (1985-12-01), Carlow
patent: 4657144 (1987-04-01), Martin et al.
GBE International plc
Hajec Donald T.
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