Coding systems

Details Coding systems Coding systems

2000-03-13

2002-05-21

Frech, Karl D. (Department: 2876)

Registers

Coded record sensors

Particular sensor structure

C235S462090, C235S494000

Reexamination Certificate

active

06390368

ABSTRACT:

This invention relates to coding systems, and is concerned in particular with novel forms of coding useful for identifying articles, methods of applying identification codes to articles, and the purpose for which the codes so applied may be used.
It is now commonplace to recycle materials rather than merely throwing them away. Indeed, in a number of Countries it is, or it soon will be, a legal requirement that articles made of paper, plastic, glass and/or metal be retrieved and recycled, and that new articles made from such substances contain a minimum amount of “old” material recovered from objects that would otherwise be disposed of in dumps, landfill sites and the like. The recycling schemes utilised may require the householder, say, to separate rubbish into different waste containers—glass in one, plastic in another, and so on—but invariably further separation is required before the relevant material can efficiently be recycled. For example, not only is there a myriad different types of plastic commonly in use, most of which are most certainly not interchangeable as regards their properties (and thus their intended use), but even such a simple object as a plastic bottle comes in many different colours and with many different sorts of contents, and a subsequent User will not wish to have a batch of new bottles of one colour discoloured by some retrieved material of another, or risk a batch of new bottles for containing, say, a drink or foodstuff being contaminated by retrieved material from bottles that had previously held engine oil or weedkiller. It is therefore important, if a recycling scheme is to be a success, to separate into quite narrowly defined groups the various materials being retrieved; this, though, requires an accurate identification of the material, which in many cases is difficult if not actually impossible.
At present most separation of retrieved materials is done by hand—that is to say, the collected waste is carried on a conveyor past a number of sorting stations at each of which a human operator visually observes what is passing, and sorts it further on the basis of experience. This, though, is difficult, and in the limited time available it is easy to mistake one type of material for another—a polyethylene plastic for a polypropylene, or enamel-coated steel for resin-painted aluminium. As a result, much effort is being devoted to some sort of machine-based identification and separation arrangement, in which the significant properties—mass/density, conductivity, magnetism, light—scattering/reflectivity, for instance—of the materials forming the articles are tested and detected by appropriate specialised apparatus. Obviously some sort of gross separation can be achieved quite easily this way; articles of light materials like paper can be “blown” away from heavier objects made of metals, and magnetic materials such as steel can be attracted away from non-magnetic materials like aluminium. It becomes more difficult, though, when trying to sort things like plastics. It is possible to identify certain plastics quite easily—PolyVinyl Chloride, for example, can be detected by the spectral and other properties of the chlorine atoms—but in general, and with the extremely broad range of possible material types, there is as yet no satisfactory way of achieving the sort of extremely narrow group separation, down to colour and even previous contents, that is really desired.
The present invention relates to an alternative way of allowing the automatic, machine-based identification of certain sorts of materials—in particular the difficult materials such as plastics, and specifically the plastics (most commonly polyethylene, polypropylene, polystyrene, polyvinyl chloride and PolyEthylene Terephthalate, or PET) used in the manufacture of containers such as bottles. More specifically, the invention concerns the use of machine-readable coded markings carried by the containers to identify not only what they are made of but also what colour they are and what they were previously used for (what they contained).
It is well-known to provide an article—a bottle, say—with machine-readable coded markings that permit a determination of some fact of interest about the article (or, if it is a container, about its contents). Thus, practically every commercial product carries on its label (or on something like a price ticket attached to the product, or even as a special marking printed directly onto the product) a bar code that identifies the product (using one or other of the several internationally-agreed and approved coding systems), and practically every large shop or supermarket has a bar code reader of some description, either hand-held or stationary, that can be used to scan the code and then interface with a stock database computer that matches the code to its stock list and then outputs an indication of what that product is and what it costs. It would undoubtedly be possible to have a waste identification and retrieval system that made use of similar codes similarly applied. However, there are significant problems involved when using coded labels in a “waste” situation. For example, they will not necessarily be in a “standard” position on the article. Moreover, they will invariably either be dirty, damaged or actually missing, and so the reader (or the Operator, in the case of a hand-held system) may be unable to find them, or, if it can, may be either unable to read them at all or may confuse one code for another. Moreover, even if, say, the regulations were to require the use of a special label in a standard place, the sheer extra cost of making that label and then applying it could well be unacceptable. The invention suggests that these problems could be overcome—or, at least, mitigated—by the use of a coding system in which the product-defining codes are integral with the article itself, conveniently being formed therein during the manufacture of the article.
It is already known to employ integral coding systems with objects such as bottles, and specifically glass bottles, in order to identify the mould from which each bottle came (so that if faulty bottles are found in the output of a multiple-mould manufacturing plant it is easier to determine where the fault is likely to have originated). The codes usually take the form of raised or recessed areas moulded into the bottle on its base or on its heel (the curved area where the base joins the wall), and these require rather specialised equipment to read them. While these types of coding might be elaborated into a system that could be utilised to define the material from which a plastic bottle is made, none of them seems capable of providing reliable readability in a waste-retrieval situation. The invention therefore proposes a quite different way in which a coded marking could be formed integrally of the article—a container such as a bottle, say—itself, and that is one where the marking takes the form of a sequence (or similar arrangement) of areas having significantly contrasting light reflecting/scattering properties actually incorporated on/in the article's surface. The contrast may be achieved in one or more of several different ways—such as by the surface being relatively rough or smooth, or being relatively raised or lowered. Such a sequence can then be scanned and read, much in the way a bar code is scanned and read, by a scanner/reader device the output of which can be fed to a suitable database and there matched to provide an identification of at least the material from which the bottle is made, and possibly also the colour of that bottle and its previous contents.
In one aspect, therefore, the invention provides a method of enabling a moulded plastics article, and especially a container such as a bottle, to carry coded markings identifying some property of that article (or its contents), in which method there is formed integrally of the article, on or in the article's surface, a code-defining sequence (or similar arrangement) of areas having significantly contrasting light reflecting/scattering proper

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