Methods and apparatus for sorting workpieces according to their color signature
First Claim
1. A method of sorting workpieces according to their colour, wherein positive colour determination is difficult for certain workpiece colours, comprising the steps of:
- (a) advancing a workpiece to be sorted towards a workstation;
(b) directing a beam of light at said workpiece to illuminate the same while said workpiece is positioned at said workstation;
(c) measuring the amplitude of three different spectral components in the light which is diffusely reflected off said workpiece, the first and second ones of said components respectively corresponding to the first and second colours of any set of three colours which satisfy the Tristimulus Theory, said third component corresponding to at least the major lobe of the third one of said set of three colours, which satisfy the Tristimulus Theory;
(d) synthesizing an amplitude which substantially corresponds to the amplitude of the spectral component that would have been measured for the third one of said set of three colours which satisfy the Tristimulus Theory, by adding the amplitude of said third component to a moiety of the amplitude of said first component;
(e) comparing the amplitudes of said first and second spectral components, and said synthesized spectral component, to successive ones of a plurality of sets of spectral component amplitudes each set of which defines a possible colour for said workpiece, thereby to determine the colour of said workpiece when the results of the comparison indicate a match;
(f) summing the amplitudes of said first and second spectral components, and said synthesized spectral component;
(g) additionally comparing the sum of the amplitudes obtained in said summing step to the sum of the amplitudes in those ones of said plurality of sets of spectral component amplitudes of greatest interest, thereby to positively determine the colour of said workpiece when the results of said additional comparison indicate a match;
(h) moving a discharge member, in accordance with the results of steps (c) through (g) until said discharge member is aligned with the receptacle assigned to receive workpieces of said determined colour; and
then,(i) releasing said workpiece from said workstation so that said workpiece traverses said discharge member and is received within said receptacle.
1 Assignment
0 Petitions
Accused Products
Abstract
Workpieces (10; FIG. 7), differing from each other only in their color, are optically sorted by illuminating the workpieces with a light beam (13) of stable color temperature. The diffuse reflection from the workpieces is analyzed by three photo-detectors, each of which is filtered to respond to a different color. Two of the colors are primary colors, as defined by the Tristimulus Theory. The third color is not a true primary color but, when added to a percentage of one of the other two colors, effectively synthesizes the third primary color. A workpiece is identified by comparing the set of Tristimulus signals it generates with a look-up table stored in the memory (25) of a microprocessor (17).
-
Citations
26 Claims
-
1. A method of sorting workpieces according to their colour, wherein positive colour determination is difficult for certain workpiece colours, comprising the steps of:
-
(a) advancing a workpiece to be sorted towards a workstation; (b) directing a beam of light at said workpiece to illuminate the same while said workpiece is positioned at said workstation; (c) measuring the amplitude of three different spectral components in the light which is diffusely reflected off said workpiece, the first and second ones of said components respectively corresponding to the first and second colours of any set of three colours which satisfy the Tristimulus Theory, said third component corresponding to at least the major lobe of the third one of said set of three colours, which satisfy the Tristimulus Theory; (d) synthesizing an amplitude which substantially corresponds to the amplitude of the spectral component that would have been measured for the third one of said set of three colours which satisfy the Tristimulus Theory, by adding the amplitude of said third component to a moiety of the amplitude of said first component; (e) comparing the amplitudes of said first and second spectral components, and said synthesized spectral component, to successive ones of a plurality of sets of spectral component amplitudes each set of which defines a possible colour for said workpiece, thereby to determine the colour of said workpiece when the results of the comparison indicate a match; (f) summing the amplitudes of said first and second spectral components, and said synthesized spectral component; (g) additionally comparing the sum of the amplitudes obtained in said summing step to the sum of the amplitudes in those ones of said plurality of sets of spectral component amplitudes of greatest interest, thereby to positively determine the colour of said workpiece when the results of said additional comparison indicate a match; (h) moving a discharge member, in accordance with the results of steps (c) through (g) until said discharge member is aligned with the receptacle assigned to receive workpieces of said determined colour; and
then,(i) releasing said workpiece from said workstation so that said workpiece traverses said discharge member and is received within said receptacle. - View Dependent Claims (2, 3, 4, 5, 6, 8, 9, 18, 19)
-
-
7. A method of determining the colour of a workpiece, wherein positive colour determination is difficult for certain workpiece colours, comprising the steps of:
-
(a) directing a beam of light at said workpiece to illuminate the same; (b) measuring the amplitude of three different spectral components in the light which is diffusely reflected off said workpiece, the first and second ones of said components respectively corresponding to the first and second colours of any set of three colours which satisfy the Tristimulus Theory, said third component corresponding to at least the major lobe of the third one of said three colours which satisfy the Tristimulus Theory; (c) synthesizing an amplitude which substantially corresponds to the amplitude of the spectral component that would have been measured for the third one of said set of three colours which satisfy the Tristimulus Theory, by adding the amplitude of said third component to a moiety of the amplitude of said first component; (d) comparing the amplitude of said first and second spectral components, and said synthesized spectral component, to successive ones of a plurality of sets of spectral component amplitudes each set of which defines a possible colour for said workpiece, thereby to determine the colour of said workpiece when the results of the comparison indicate a match; (e) summing the amplitudes of said first and second spectral coomponents, and said synthesized spectral component; and
then(f) additionally comparing the sum of the amplitudes obtained in said summing step to the sum of the amplitudes in those ones of said plurality of sets of spectral component amplitudes of greatest interest, thereby to positively determine the colour of said workpiece when the results of said additional comparison indicate a match. - View Dependent Claims (10, 11, 12, 13)
-
-
14. An apparatus for sorting workpieces according to their colour, wherein positive colour determination is difficult for certain workpiece colours, comprising:
-
(a) means for advancing a workpiece to be sorted towards a workstation; (b) means for directing a beam of light at said workpiece to illuminate the same while said workpiece is positioned at said workstation; (c) means for measuring the amplitude of three different spectral components in the light which is diffusely reflected off said workpiece, the first and second ones of said components respectively corresponding to the first and second colours of any set of three colours which satisfy the Tristimulus Theory, said third component corresponding to at least the major lobe of the third one of said set of three colours, which satisfy the Tristimulus Theory; (d) means for synthesizing an amplitude which substantially corresponds to the amplitude of the spectral component that would have been measured for the third one of said set of three colors which satisfy the Tristimulus Theory, by adding the amplitude of said third component to a moiety of the amplitude of said first component; (e) means for comparing the amplitudes of said first and second spectral components, and said synthesized spectral component, to successive ones of a plurality of sets of spectral component amplitudes each set of which defines a possible colour for said workpiece, thereby to determine the colour of said workpiece when the results of the comparison indicate a match; (f) means for summing the amplitudes of said first and second spectral components, and said synthesized spectral component; (g) means for additionally comparing the sum of the amplitudes to the sum of the amplitudes in those ones of said plurality of sets of spectral component amplitudes of greatest interest, thereby to positively determine the colour of said workpiece when the results of said additional comparison indicate a match; (h) means for moving a discharge member until said discharge member is aligned with the receptacle assigned to receive workpieces of said determined colour; and (i) means for releasing said workpiece from said workstation so that said workpiece traverses said discharge member and is received within said receptacle. - View Dependent Claims (15, 16, 17, 21, 22)
-
-
20. An apparatus for of determining the colour of a workpiece wherein colour determination is difficult for certain workpiece colours, comprising:
-
(a) means for directing a beam of light at said workpiece to illuminate the same (b) means for measuring the amplitude of three different spectral components in the light which is diffusely reflected off said workpiece, the first and second ones of said components respectively corresponding to the first and second colours of any set of three colours which satisfy the Tristimulus Theory, said third component corresponding to at least the major lobe of the third one of said three colours which satisfy the Tristimulus Theory; (c) means for synthesizing an amplitude which substantially corresponds to the amplitude of the spectral component that would have been measured for the third one of said set of three colours which satisfy the Tristimulus Theory, by adding the amplitude of said third component to a moiety of the amplitude of said first component; (d) means for comparing the amplitude of said first and second spectral components, and said synthesized spectral components, to successive ones of a plurality of sets of spectral component amplitudes each set of which defines a possible colour for said workpiece, thereby to determine the colour of said workpiece when the results of the comparison indicate a match; (e) means for summing the amplitudes of said first and second spectral components, and said synthesized spectral component; and (f) means for additionally comparing the sum of the amplitudes to the sum of the amplitudes in those ones of said plurality of sets of spectral component amplitudes of greatest interest, thereby to positively determine the colour of said workpiece when the results of said additional comparison indicate a match. - View Dependent Claims (23, 24, 25, 26)
-
Specification