EP0441012A2
Expired / Lapsed
EP
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Method for sorting plastic articles
Assignee: Hoover Universal Inc
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Filing: 1990-12-28
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Granted: —
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Expires: 2010-12-28
Abstract
Abstract A method of sorting a mixed group of plastic articles, such as PET and PVC containers, involves individually subjecting each article to a beam of electromagnetic radiation, and detecting a change in the intensity of the beam. The measured intensity varies in a manner indicative of the crystallinity of the plastic from which the article is made, and hence identifies the type of plastic the article is made of. Each article is then sent to one of a plurality of destinations, such as recycling collection bins, according to the type of plastic. The method is particularly useful in separating PET and PVC used in containers, since these plastics are very difficult to sort by conventional methods. <IMAGE>
Inventors
- 👤 Glenn Trischan
- 👤 Louis Cartz
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-05 15:50
CPC Classifications
B; B29; B29B; B29B17/00; B29B17/02; B07; B07C; B07C5/00; B07C5/34; B07C5/3416; B07C5/342; B29B2017/0203; B29B2017/0213; B29B2017/0279; B29K; B29K2023/00; B29K2023/10; B29K2023/12; B29K2025/00; B29K2027/00; B29K2027/06; B29K2033/00; B29K2033/04; B29K2033/12; B29K2067/00; B29K2105/00; B29K2105/06; B29K2105/065; B29L; B29L2031/00; B29L2031/712; B29L2031/7158; B29L2031/744; Y; Y02; Y02W; Y02W30/00; Y02W30/50; Y02W30/62; Y10; Y10S; Y10S209/00; Y10S209/942
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
123 words
A method for sorting a mixed group of plastic articles, which group contains at least two types of articles made of different plastics and having a crystallinity indicative of each type of plastic, comprising the steps of: subjecting each one of the plastic articles in the group to a beam of electromagnetic radiation having a frequency such that transmission, reflection and diffraction of the radiation are substantially affected by the crystallinity of the plastic; then detecting the intensity of the affected portion of the beam, which intensity varies in a manner indicative of the crystallinity of the plastic from which the article is made; and then sending each article to one of a plurality of destinations according to the crystallinity of each article.
Claim 2
Independent Claim
144 words
A method for sorting a mixed group of plastic articles, which group contains at least two types of articles made of different plastics and having a birefringency indicative of each type of plastic, comprising the steps of: transporting each one of the plastic articles between a pair of spaced, opposed first and second light polarizing filters oriented for extinction of light passing therethrough; illuminating each of the articles with a beam of light directed to pass successively through the first filter, the article, and the second filter; detecting the intensity of the beam on the side of the second filter opposite the article, which intensity varies in a manner indicative of the birefringency of the plastic from which the article is made; and sending each article to one of a plurality of destinations according to the type of plastic each article is made of.
Claim 3
Independent Claim
151 words
An apparatus for sorting a mixed group of plastic articles, which group contains at least two types of articles made of different plastics and having a birefringency indicative of each type of plastic, comprising: a pair of spaced, opposed first and second light polarizing filters oriented for attenuation of light passing therethrough; means for transporting each one of the plastic articles between the filters; means for illuminating each of the articles with a beam of light directed to pass successively through the first filter, the article, and the second filter; means for detecting the intensity of the beam on the side of the second filter opposite the article, which intensity varies in a manner indicative of the birefringency of the plastic from which the article is made; and means for sending each article to one of a plurality of destinations according to the type of plastic each article is made of.
Claim 4
Independent Claim
135 words
A method for sorting transparent plastic articles of varying birefringence, comprising: feeding a series of the plastic articles to a scanning unit, the scanning unit including a light source, a detector for indicating the intensity of light from the light source, a polarizer and an analyzer, the polarizer and analyzer being disposed for extinction of light from the light source traveling along a pathway from the light source to the detector, each article being interposed in the light pathway following the polarizer and before the analyzer; detecting the intensity of light from the light source at the detector; and routing each plastic article to one of a plurality of destinations based on the intensity registered by the detector, which intensity is indicative of the birefringence of the plastic from which the plastic article is made.
Claim 5
Dependent Claim
20 words
The method of claim 4, wherein the plastic articles comprise a mixture of polyethylene terephthalate articles and polyvinyl chloride articles.
Claim 6
Dependent Claim
11 words
The method of claim 5, wherein the articles are beverage containers.
Claim 7
Dependent Claim
55 words
The method of claim 4, wherein the method further comprises: transporting the articles on a conveyer one at a time to the scanning unit; diverting a group of articles of like birefringency from the conveyer; and continuing to transport the remainder of the articles on the conveyer to a different destination than the diverted group.
Claim 8
Dependent Claim
22 words
The method of claim 4, wherein the light source produces visible light and the detector measures the intensity of such visible light.
Claim 9
Dependent Claim
29 words
The method of claim 4, wherein the plastic article is interposed between the polarizer and analyzer so that the light from the light source passes through the plastic article.
Claim 10
Dependent Claim
41 words
The method of claim 4, wherein the polarizer and analyzer, light source and detector are positioned on the same side of the plastic article so that the light from the light source reflects off of the surface of the plastic article.
Claim 11
Dependent Claim
20 words
The method of claim 6, further comprising a step of flattening the containers prior to feeding to the scanning unit.
Claim 12
Dependent Claim
20 words
The method of claim 6, further comprising a step of delabeling each container prior to feeding to the scanning unit.
Claim 13
Independent Claim
106 words
An apparatus for sorting transparent plastic articles of varying birefringence, comprising: a substantially opaque housing having a first, centrally located opening along its length, a cover for such first opening, and a second opening at one end thereof; a light source disposed within the housing at the end remote from the second opening; a polarizer disposed within the housing between the light source and the first opening; and an analyzer disposed in the housing on the side of the first opening opposite the polarizer and spaced from the polarizer to permit insertion of each transparent plastic article between the polarizer and analyzer through the first opening.
Claim 14
Independent Claim
104 words
A method for sorting plastic articles of varying crystallinity, comprising: feeding a series of the plastic articles to a scanning unit, the scanning unit including an X-ray source and an X-ray detector, the detector being positioned to measure X-rays from the source which are diffracted by the article being scanned due to Bragg scattering; detecting the intensity of diffracted X-rays from the X-ray source at the detector; and routing each plastic article to one of a plurality of destinations based on the intensity registered by the detector, which intensity is indicative of the crystallinity of the plastic from which the plastic article is made.
Claim 15
Dependent Claim
35 words
The method of claim 14, wherein the source and detector are positioned on the same side of the article to be scanned so that the diffracted X-rays reflect off of the surface of the article.
Claim 16
Dependent Claim
59 words
The method of claim 14, wherein the source and detector are located on opposite sides of the article being scanned, so that an incident X-ray beam passes entirely through the article being scanned, and a beam stopper is interposed between the article and the detector to prevent the detector from detecting X-rays diffracted by less than a predetermined angle.
Claim 17
Dependent Claim
13 words
The method of claim 14, wherein the articles are PET and PVC containers.
Claim 18
Independent Claim
148 words
An apparatus for sorting a mixed group of plastic articles, which group contains at least two types of articles made of different plastics and having a crystallinity indicative of each type of plastic, comprising: a conveyer for transporting each plastic article one after another; a scanning unit for subjecting each one of the plastic articles in the group to a beam of electromagnetic radiation having a frequency such that transmission, reflection and diffraction of the radiation are substantially affected by the crystallinity of the plastic; a detector for measuring the intensity of the affected portion of the beam, which intensity varies in a manner indicative of the crystallinity of the plastic from which the article is made; and means for selectively diverting a group of articles of like crystallinity from the conveyer to a first destination, the conveyer transporting the remainder of the articles to a second destination.
Claim 19
Dependent Claim
70 words
The apparatus of claim 18, wherein the article diverting means comprises an arm positioned to extend over the top surface of the conveyer so as to contact the article being scanned and move it off of the conveyer, means for extending and retracting the arm, and control means connected to the detector for actuating the arm extending and retracting means in response to a predetermined intensity measured by the detector.
Claim 20
Dependent Claim
22 words
The apparatus of claim 18, further comprising means for intermittently stopping the conveyer to permit the scanning unit to scan each article.
References Cited (Backward Citations)
No citation records indexed.
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