Classifying – separating – and assorting solids – Sorting special items – and certain methods and apparatus for... – Condition responsive means controls separating means
Patent
1997-06-20
1999-09-21
Milef, Boris
Classifying, separating, and assorting solids
Sorting special items, and certain methods and apparatus for...
Condition responsive means controls separating means
209587, 209639, B03B 524
Patent
active
059542063
DESCRIPTION:
BRIEF SUMMARY
This invention relates to optical inspection systems and/or sorting systems. The invention is especially directed to optical inspection systems for use in the control of fruit or vegetable sorting systems and harvesters, in packing houses or in canning factories.
Systems of this kind are used to inspect typically the ripeness of the fruit or vegetable and/or the presence of dirt clods or other foreign materials and/or the presence of colour defects and to establish criteria for separating good product from defective product or other unwanted matter.
Specific examples are checking the ripeness of tomatoes or fruit. In a known system, light incident upon tomatoes is reflected and the reflected light monitored to establish the degree of ripeness of the product and/or the presence of dirt and/or product defects. In particular arrangements, light emitting diodes, LEDs, are used, to direct light onto product typically falling past the light sources. A number of disadvantages are however apparent in existing systems of this kind, in particular associated with build-up of dirt on windows through which the light is usually directed and behind which the light sources and also the light sensors are located.
A further problem is adherence of product portions or other extraneous material to whatever feature defines the rear boundary of the target region, typically a curtain, as such unwanted matter or dirt may reflect light back thereby giving spurious indications. A still further problem arising out of illuminating an inspection zone or region with LEDs is that the illumination across the inspection region may be patchy or non-uniform, which leads to non-uniform inspection sensitivity.
It is an object of the invention to provide an optical-light product inspection system overcoming at least in part certain of the disadvantages identified above.
According to the invention, there is provided an optical inspection system for edible natural products comprising an inspection region through which said products pass, means for directing light onto said products during their passage through said inspection region, and means for detecting light returned from said products, wherein said means for directing light onto the products comprises an optical system for focussing light substantially at a specified target region within said inspection region.
The system of the invention may comprise a plurality of said light directing means, in particular two said light directing means.
The or each light directing means suitably comprises a multiplicity of light emitting sources and a lens system for focussing light emanating from said sources substantially at said target region. Preferably, said multiplicity of light emitting sources comprises a first multiplicity of said sources for emitting light of at least one first wavelength and at least one further multiplicity of said sources for emitting light of at least one second wavelength, said at least one first wavelength and said at least one second wavelength being selected in dependence on optical characteristics of the products to be inspected, and the number of said first multiplicity of said sources of said at least one first wavelength may be balanced against or matched to the number of said further multiplicity of said sources of said at least one second wavelength, so that substantially similar processing may be applied to signals provided by said returned light detecting means substantially independently of the wavelength of the returned light. Said at least one second wavelength is suitably different from said at least one first wavelength, but where a multiplicity of first and second wavelengths are used, so that the first multiplicity of sources includes sources of a variety of wavelengths as also does the second multiplicity, then at least some of the second wavelengths may be the same as some of the first wavelengths. Thus partial overlap of wavelengths may exist in certain circumstances.
In a favoured embodiment of the system of the invention, said light emitting sources
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Mallon John
Moynihan Maurice
Milef Boris
Oseney Limited
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