Classifying – separating – and assorting solids – Sorting special items – and certain methods and apparatus for... – Condition responsive means controls separating means
Reexamination Certificate
2000-03-07
2002-07-09
Nguyen, Tuan N. (Department: 3653)
Classifying, separating, and assorting solids
Sorting special items, and certain methods and apparatus for...
Condition responsive means controls separating means
C209S587000, C209S938000, C194S328000
Reexamination Certificate
active
06417471
ABSTRACT:
SPECIFICATION
The present invention relates to a device for recognizing coins, comprising a transmitter element for electro-magnetic radiation, a receiver element for electro-magnetic radiation, by means of which an electrical measuring signal corresponding to the incoming radiation is generated, the arrangement of said transmitter and receiver elements being made such that electro-magnetic radiation emitted by said transmitter element acts on a coin brought into a test position and that at least part of the reflected radiation of the incoming electro-magnetic radiation reflected by the coin acts on said receiver element, and comprising an evaluator unit connected to said receiver element, by means of which by comparison of the electrical measuring signal generated by said receiver element and possibly electronically further processed to a given comparison signal a “false” control signal or a “true” control signal can be generated. A device for recognizing coins serves for differentiation between false and true coins and for differentiation between true, however different coins. Coins recognized as false will be fed to a separate collector system. True however different coins are sorted. Of course, both functions can be combined. In the case of sorting, in the simplest case,. the “true” control signal corresponds for instance to a “correct” control signal to be sorted, and the “false” control signal would correspond to coin types not to be sorted. In case of sorting, of course more than two alternative comparison signals, and control signals may exist, then one control signal being assigned to each coin type or group of coin types. The term electro-magnetic radiation comprises for instance wavelength ranges from the cm range to the mm range. In particular the range of the visible light, near u.v. light and near and far i.r. light can be used. If electro-magnetic radiation hits a border surface, for instance a solid body surface, the radiation will interact with the solid body. Depending of the entering angle and the di-electric properties of the solid body, at least part of the intensity, in case of a total reflection the complete incoming radiation will be reflected, the degree of reflectivity further depending on the angle between incoming radiation and surface normal of the solid body. In this context, reference is made to basic physical publications about reflection.
A device of the design referred to hereinbefore is known from document DE 195 07 482 A1. In the so far prior art device, visible light is radiated on a surface of a coin, and the reflected light is detected by means of a lens-optical system in the manner of a picture as an electrical signal or a data set, resp. The electrical signal or the data set thereof, resp., corresponding to a picture is compared to a reference data set, and thus a comparison between a “given picture” and an “actual picture” is performed. In case of deviations, a “false” signal is generated. In other words, the prior art device operates with an optical pattern recognition system performing comparisons to given patterns. This procedure is very expensive with regard to data technology or software, resp. Further, geometrical operations have to be performed with the detected optical patterns, since the position of a coin at pattern recognition cannot easily be reproducibly determined. Moreover, it is difficult to find criteria for the admissible degree of pattern deviations which will still permit reliable selections or assignments of the coins. In the reference document cited above, further an evaluation of brightness values for differentiation between alloys is mentioned, this is however per se little reliable for instance due to the different oxidation degrees of coin surfaces.
Given this prior art, it is the technical aim of the invention to provide a device for recognizing coins that operates in a simpler way however at high reliability.
For achieving this aim, the invention teaches that a wavelength-selective measuring and evaluating signal can be produced in the receiver element and the evaluator unit, and that the control signals can be produced by the evaluator unit according to a comparison of the wavelength-selective evaluating signal to given wavelength-selective comparison signal bands. The term wavelength-selective means that not a broad spectrum of electro-magnetic radiation is detected, but rather a small band only. In the case of light this means that for instance only one color is detected, corresponding to a line width &Dgr;&lgr;/&lgr;(&lgr;=wavelength with maximum radiation intensity, &Dgr;&lgr;=line width at 0.5 times maximum radiation intensity) of less than 0.4, preferably 0.2, for instance approx. 0.1 to 0.06. A wavelength-selective measuring signal can be achieved in the receiver element by way of the wavelength-selective radiation from the transmitter element and/or of the wavelength-selective detection in the receiver unit. A wavelength-selective measuring signal can be obtained on the detection side by various methods. For instance, the receiver element may include a wavelength-selective sensor or be provided with a wavelength-selective filter in front of a sensor. In this case, the receiver unit needs not to operate in a wavelength-selective manner. It is further possible to modulate a wavelength-selective electro-magnetic radiation coming from a transmitter element, and to establish by de-modulation in a not or only slightly wavelength-selective receiver element or in ad evaluator unit arranged therebehind a specific assignment to the emitted electro-magnetic radiation. A comparison signal band is a given measuring and evaluating signal range, in particular a signal intensity range, being assigned to coin conditions “false” or “true”, measuring and evaluating signals outside this signal range being assigned to the respectively other coin condition. In principle, both borders of the comparison s signal band are sharp, however there can be provided subsections at the borders being assigned to a coin condition “not sure”. The comparison signal band or its borders or border sections, resp., can easily be determined by tests with true and false coins. Corresponding conditions apply to an embodiment having a (if applicable, additional) sorting function.
The invention is initially based on the fact that total reflection will not always and in a wavelength-independent manner occur at metal surfaces in the sense that the degree of reflection is precisely 100%. Rather various absorption processes take place, said absorption processes being wavelength-dependent. On the one hand, the wavelength dependencies of the dielectric constant of the body material, in particular however, on the other hand, the electronic properties of surface layers, as for instance oxide layers, are responsible for this. Said oxide layers will affect reflectivity to a substantial extent and in a wavelength-dependent manner, depending on chemical composition. Absorption and thus also reflection are thus substantially determined by the material of the coins. Thus, by adjustment of the wavelength and maybe of the entering angle of the radiation, a particularly safe differentiation with regard to coins of different chemical composition can be achieved, and this practically independent from the degree of oxidation of the coin. As a result, the optical device according to the invention operates in a particularly simple manner (no pattern recognition required), and nevertheless in a particularly reliable manner.
In principle, a wavelength-selective measuring signal can be obtained, if the transmitter element can emit electro-magnetic radiation in a wavelength-selective manner, and/or the receiver element can receive electro-magnetic radiation in a wavelength-selective manner. A particularly simple and reliable embodiment of the invention is characterized by that the transmitter element comprises a luminescence diode. Luminescence diodes are p-n semiconductor elements with a material-dependent band gap. The measure of the band gap to determin
F. Zimmerman GmbH & Co., KG
Millen White Zelano & Branigan P.C.
Nguyen Tuan N.
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