Method and apparatus for near-infrared sorting of recycled plastic waste
First Claim
1. A method of distinguishing samples of at least a first plastic material and a second plastic material having different electromagnetic energy reflection, absorption and penetration characteristics, comprising the steps of:
- conveying samples of plastic materials to be distinguished from at least one inlet toward at least one outlet through an electromagnetic energy illumination zone;
illuminating the samples with electromagnetic energy while transiting the illumination zone;
receiving electromagnetic energy passing through the samples while transiting the illumination zone;
splitting the received electromagnetic energy passing through the samples into a first stream and a second stream;
passing the electromagnetic energy of said first stream through a bandpass filter having a preselected bandwidth characterized in that the first plastic material exhibits an absorptive peak of the electromagnetic energy passing through a sample of the first plastic material, and for which the second plastic material exhibits a higher level of electromagnetic energy passing through a sample of the second plastic material than a sample of said first plastic material;
passing the electromagnetic energy of said second stream through a bandpass filter having a second preselected band characterized in that the level of electromagnetic energy passing through the second plastic material is about equal to the level of electromagnetic energy passing through the second plastic material passed by said first bandpass filter;
measuring the level of the electromagnetic energy of an illuminated sample passed by said first bandpass filter;
measuring the level of the electromagnetic energy of said illuminated sample passed by said second bandpass filter; and
comparing the respective levels of electromagnetic energy of said illuminated sample passed by said first bandpass filter and said second bandpass filter.
6 Assignments
0 Petitions
Accused Products
Abstract
Method and apparatus for sorting plastic materials on a recycling operation wherein near and infrared energy illuminates particles of flake plastic including such as PET, PVC and PS transported along a conveyer line and the contaminant ingredients are identified and ejected from the stream of preferred particles. More accurate sorting, and thus a higher quality sort may be performed where the contaminant materials and the preferred materials are identified by comparing ratios of levels of signals of energy transmitted through or reflected from the particles, the levels of signal being obtained by filtering the energy from the particles through bandpass filters, one filter of which is centered on the absorptive peak of a contaminant and another filter is centered on a frequency exhibiting the energy level of the preferred material equal to that occurring at the center of the filter for the contaminant absorptive peak. Collateral method and apparatus include placing the fiber optic energy receivers of the transmitter and received information at a distance from the receiver a factor or five or more of the ratio of the field of view of a fiber at the particle stream to the maximum offset of the receiving fibers in the faceplate, as those opposite each other on a diameter of the faceplate.
37 Citations
30 Claims
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1. A method of distinguishing samples of at least a first plastic material and a second plastic material having different electromagnetic energy reflection, absorption and penetration characteristics, comprising the steps of:
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conveying samples of plastic materials to be distinguished from at least one inlet toward at least one outlet through an electromagnetic energy illumination zone;
illuminating the samples with electromagnetic energy while transiting the illumination zone;
receiving electromagnetic energy passing through the samples while transiting the illumination zone;
splitting the received electromagnetic energy passing through the samples into a first stream and a second stream;
passing the electromagnetic energy of said first stream through a bandpass filter having a preselected bandwidth characterized in that the first plastic material exhibits an absorptive peak of the electromagnetic energy passing through a sample of the first plastic material, and for which the second plastic material exhibits a higher level of electromagnetic energy passing through a sample of the second plastic material than a sample of said first plastic material;
passing the electromagnetic energy of said second stream through a bandpass filter having a second preselected band characterized in that the level of electromagnetic energy passing through the second plastic material is about equal to the level of electromagnetic energy passing through the second plastic material passed by said first bandpass filter;
measuring the level of the electromagnetic energy of an illuminated sample passed by said first bandpass filter;
measuring the level of the electromagnetic energy of said illuminated sample passed by said second bandpass filter; and
comparing the respective levels of electromagnetic energy of said illuminated sample passed by said first bandpass filter and said second bandpass filter. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. Apparatus for distinguishing samples of at least a first plastic material and a second plastic material having different electromagnetic energy absorption and penetration characteristics, comprising the steps of:
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conveying means moving samples of plastic materials from an inlet end to an outlet end having an electromagnetic energy illumination zone intermediate the inlet end and outlet end;
an electromagnetic energy source disposed adjacent the illumination zone; and
receiving means for receiving electromagnetic energy passing through samples of plastic materials illuminated by said electromagnetic energy source;
a beamsplitter for separating the received electromagnetic energy passing through a sample into a first stream and a second stream;
a bandpass filter for filtering the electromagnetic energy of said first stream, said filter having a preselected bandwidth characterized in that the first plastic material exhibits an absorptive peak of the electromagnetic energy passing through the sample, and for which a the second plastic material exhibits a higher level of electromagnetic energy passing therethrough;
a second bandpass filter for filtering the electromagnetic energy of said second stream, said filter having a second preselected band width characterized in that the level of electromagnetic energy passing through the second plastic material is about equal to the level of electromagnetic energy passing through the second plastic material passed by said first bandpass filter;
means for measuring the level of the electromagnetic energy of an illuminated sample of plastic material passed by said first bandpass filter;
means for measuring the level of the electromagnetic energy of an illuminated sample of plastic material passed by said second bandpass filter; and
means for comparing the respective levels of electromagnetic energy of said illuminated sample passed by said first bandpass filter and said second bandpass filter. - View Dependent Claims (9, 10, 11, 12, 13, 14, 15)
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16. A method of distinguishing samples of at least a first plastic material and a second plastic material having different electromagnetic energy reflection, absorption and penetration characteristics, comprising the steps of:
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conveying samples of plastic materials to be distinguished from at least one inlet toward at least one outlet through an electromagnetic energy illumination zone;
illuminating the samples with electromagnetic energy while transiting the illumination zone;
receiving electromagnetic energy reflected from the samples while transiting the illumination zone;
splitting the received electromagnetic energy reflected from the samples into a first stream and a second stream;
passing the electromagnetic energy of said first stream through a bandpass filter having a preselected bandwidth characterized in that the first plastic material exhibits an absorptive peak of the electromagnetic energy passing through a sample of the first plastic material, and for which the second plastic material exhibits a higher level of electromagnetic energy reflected from a sample of the second plastic material than a sample of said first plastic material;
passing the electromagnetic energy of said second stream through a bandpass filter having a second preselected band characterized in that the level of electromagnetic energy reflected from through the second plastic material is about equal to the level of electromagnetic energy reflected from the second plastic material passed by said first bandpass filter;
measuring the level of the electromagnetic energy of an illuminated sample passed by said first bandpass filter;
measuring the level of the electromagnetic energy of said illuminated sample passed by said second bandpass filter; and
comparing the respective levels of electromagnetic energy of said illuminated sample passed by said first bandpass filter and said second bandpass filter. - View Dependent Claims (17, 18, 19, 20, 21, 22)
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23. Apparatus for distinguishing samples of at least a first plastic material and a second plastic material having different electromagnetic energy absorption and penetration characteristics, comprising the steps of:
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conveying means moving samples of plastic materials from an inlet end to an outlet end having an electromagnetic energy illumination zone intermediate the inlet end and outlet end;
an electromagnetic energy source disposed adjacent the illumination zone; and
receiving means for receiving electromagnetic energy reflected from samples of plastic materials illuminated by said electromagnetic energy source;
a beamsplitter for separating the received electromagnetic energy reflected from a sample into a first stream and a second stream;
a bandpass filter for filtering the electromagnetic energy of said first stream, said filter having a preselected bandwidth characterized in that the first plastic material exhibits an absorptive peak of the electromagnetic energy reflected from the sample, and for which a the second plastic material exhibits a higher level of electromagnetic energy reflected therefrom;
a second bandpass filter for filtering the electromagnetic energy of said second stream, said filter having a second preselected band width characterized in that the level of electromagnetic energy reflected from the second plastic material is about equal to the level of electromagnetic energy reflected from the second plastic material passed by said first bandpass filter;
means for measuring the level of the electromagnetic energy of an illuminated sample of plastic material passed by said first bandpass filter;
means for measuring the level of the electromagnetic energy of an illuminated sample of plastic material passed by said second bandpass filter; and
means for comparing the respective levels of electromagnetic energy of said illuminated sample passed by said first bandpass filter and said second bandpass filter. - View Dependent Claims (24, 25, 26, 27, 28, 29, 30)
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Specification