EP1035519A1 - Coin recognition device - Google Patents

Abstract

The device includes a transmitter unit (1), and a receiver unit (2) for detecting electromagnetic radiation reflected from a coin. A wavelength selective measuring and evaluation signal (12) is generated in the receiver unit (2) and an evaluation unit (6). The evaluation unit generates control signals according to a comparison of the wavelength selective evaluation signal, in given wavelength selective comparison signal bands. The transmitter may be a luminescent diode. An Independent claim is included for a method of testing coins.

Description

The invention relates to a device for coin recognition, with a transmitter element for electromagnetic Radiation, with a receiver element for electromagnetic Radiation with which according to the on it radiated an electrical Measurement signal can be generated, the arrangement of the Sender element and the receiver element with the Provided that radiated from the transmitter element electromagnetic radiation on an in a coin placed in a test position and that at least part of one emitted by the coin Reflection radiation from the incident electromagnetic Radiates radiation onto the receiver element, and with one with the receiver element connected electronic evaluation unit, by means of which according to a comparison of that of the receiver element generated and possibly processed electronically electrical measurement signal with a predetermined Comparison signal alternatively a "false" control signal or a "real" control signal can be generated. - One Device for coin recognition is used to remove incorrect ones to distinguish real coins from real but different ones Distinguish coins from each other. As incorrectly recognized coins are kept in a separate collection fed. Real but different coins sorted. Both functions can of course can be combined with each other. In the case of sorting corresponds in the simplest case, for example "real" control signal a "correct" control signal regarding a coin to be sorted out and that "false" control signal referred to unsorted Coin types. In case of sorting you can of course also more than two alternative comparison signals and control signals are present, where then one control signal each for one coin type or is assigned to a coin type group. The term of electromagnetic radiation for example, wavelength ranges from the cm range to in the nm range. In particular, the area of visible light, near UV light and near and far IR light can be used. Meets electromagnetic Radiation on an interface, for example on a solid surface, the radiation enters Interaction with the solid. Depending on that Irradiation angle and the dielectric properties of the solid is at least a part, in In the case of total reflection, practically the whole radiated power reflected, the degree of reflection also from the angle of the irradiation to Surface normal of the solid depends. To do this in addition to basic physical publications referred for reflection.

A device of the above construction is known from the literature DE 195 07 482 A1. At The device known in this respect becomes visible Light shone onto a surface of a coin and that reflected light with a lens optical system figuratively as an electrical signal or as a data set detected. The electrical signal corresponding to an image or its data record is marked with a Reference data record compared and so a comparison between a "target image" and an "actual image". In the event of deviations, a "false" signal is generated generated. In other words, it works previously known device with an optical pattern recognition system, which is a comparison with target patterns carries out. This procedure is data-related or very expensive in terms of software. In addition, with geometric operations based on the detected optical patterns be carried out as the position of a Coin is not easily reproducible during pattern recognition is definable. It is also difficult a criterion for the allowable degree of pattern deviation to find which is still reliable Selection or classification of coins allowed. In the mentioned reference is also an evaluation of brightness values to differentiate alloys addressed, but this is in itself little reliable due to, for example, the different Degree of oxidation of coin surfaces.

In contrast, the invention is the technical problem based on a device for coin recognition create which is simpler but with high reliability works.

To solve this problem, the invention teaches that in the receiver element and the evaluation unit a wavelength selective Measurement and evaluation signal can be generated and that the control signals with the evaluation unit according to a comparison of the wavelength selective Evaluation signals with predefined wavelength selective Comparison signal bands can be generated. - With the term wavelength selective means that not a wide range of electromagnetic Radiation is detected, but only a narrow band. In the case of light, this means that, for example, only a color is detected, which corresponds to a line width Δλ / λ (λ = Wavelength with maximum radiation power, Δλ = Line width at 0.5 of the maximum radiation power) less than 0.4, preferably less than 0.2, for example, approximately 0.1-0.06. On Wavelength selective measurement signal can in the receiver element in the way of wavelength selective radiation from the transmitter element and / or the wavelength selective Detection takes place in the receiver unit. On Wavelength-selective measurement signal can be on the detection side preserved in various ways become. For example, the receiver element can have wavelength-selective sensor or with a a wavelength selective filter upstream of a sensor be equipped. Then the transmitter unit needs not to work wavelength selective. It is also possible, a wavelength selective emitted by the transmitter element electromagnetic radiation too modulate and not by demodulation in one or only slightly wavelength-selective receiver element or in one of these evaluation units a specific assignment to the radiated to hit electromagnetic radiation. As a comparison signal band is a given measurement and Evaluation signal area, in particular a signal intensity area, designated, which is a coin condition "wrong" or "real" is associated with being outside measurement and evaluation signals lying in this signal range assigned to the other coin condition are. Basically, the two limits of the comparison signal band sharp, it can on the borders however, sub-areas can also be provided, which one Coin status "unsafe" are assigned. The comparison signal band or its borders or border areas can be easily experimented with determine real and false coins. Corresponding applies to an embodiment with (possibly additional) Sort function.

The invention is based first on the knowledge that on metallic surfaces not always and regardless of wavelength a real total reflection takes place in the sense that the reflectance is exactly 100% is. Rather, there are various absorption processes instead, these absorption processes depending on the wavelength are. For this, on the one hand responsible for the wavelength dependencies of the dielectric constant the hull material, in particular but also the electronic ones Properties of surface layers, such as Oxide layers. The latter influence the reflectivity to a considerable extent wavelength-dependent, and depending on the chemical composition. The Absorption and consequently also the reflection in a The predetermined wavelength is therefore considerably determined from the coin material. Thus, by voting of wavelength and, if applicable, angle of incidence to a specific one Coin alloys make a particularly secure distinction compared to other chemical coins Composition to be taken, and also practical regardless of the "degree of tarnishing" of the coin. in the Result works the optical according to the invention Device particularly simple (no pattern recognition required) and yet particularly reliable.

In principle, a wavelength-selective measurement signal can be obtained if electromagnetic radiation can be emitted in a wavelength-selective manner with the transmitter element and / or electromagnetic radiation can be recorded in a wavelength-selective manner with the receiver element. A particularly simple and reliable embodiment of the invention is characterized in that the transmitter element has a luminescent diode. Luminous diodes are pn semiconductor elements with a material-dependent band gap. The measure of the band gap determines the wavelength of the emitted radiation. Examples are: GaAs, Si doped: IR; GaP, Zn-, O-doped: red; GaAs _0.6 P _0.4 : red; GaAs _0.35 P _0.65 , N-doped: orange; GaAs _0.15 P _0.85 , N-doped: yellow; GaP, N-doped: green; SiC, Al-, N-doped: blue; GaN, Zn-doped: blue. The line width is typically approximately 40 nm.

A special embodiment of the invention is characterized in that the transmitter element several has wavelength-selective transmitter units, where the radiation spectra of the transmitter units are not overlapping and that in Receiver element preferably separate, each Measurement signals assignable to a transmitter unit can be generated are. Non-overlapping means that the wavelengths of the Radiant power maxima are more than half Differentiate line width. For example, from the aforementioned luminescent diodes two different colors Types, i.e. with different band gaps, if necessary in a structural unit.

Because simultaneously at two different wavelengths is worked on, will be further improved Functional safety created because the wavelength-specific Reflective properties of a particular Materials at different wavelengths each for find oneself. But also with one only with regard to the measurement signals Evaluation unit to be worked, i.e. no separate measurement signals are generated.

The transmitter element is preferably for radiation modulated electromagnetic waves. Modulated means amplitude-modulated, for example with a rectangular or sinusoidal Envelope. The modulation frequency can range from 50 Hz to 20 MHz, preferably from 50 Hz to 1 MHz, most preferably from 200 Hz to 20 kHz. In the embodiment with, for example, two different colors Luminescent diodes can be the different Luminous diodes with different and in the receiver element or the evaluation unit to be provided with discriminatory modulations, for example different modulation frequencies. By means of the modulation in each embodiment Influences of extraneous light or daylight are practical locked out.

The receiver element can be a photoresistor, a pn photodiode, a pin photodiode, an avalanche photodiode or have a phototransistor. At the latter two components are Internal gain detectors. The spectral sensitivity the aforementioned components is opposite the emission spectrum of luminescent diodes, for example relatively wavelength-selective.

The transmitter element and the receiver element are like this aligned that the directions are maximum Radiation intensity as well as maximum sensitivity each identical or different at an angle of 0 - 50 °, preferably 5 - 30 °, most preferably 14 - 16 °, stand normal on a main coin surface. The latter angular range is particularly recommended in the case of leaded coins and in combination with yellow or orange light. For others Coin metals can combine other angular ranges can be attached with other colors and by simple experiments metal-specific or alloy-specific be optimized.

A special embodiment of the invention is characterized in that the transmitter element a Oscillator for modulating the emitted electromagnetic Has radiation, and that the Evaluation unit for an AC voltage amplifier Amplification of the measurement signal, preferably with a filter, a detector for demodulating the measurement signal, preferably a rectifier, and a DC amplifier to reinforce the demodulated Signal and a comparator for comparing the demodulated Signal with a predetermined DC voltage range having. The specified DC voltage range is coin-specific or alloy-specific and can, for example, by measurements Reference coins can be determined. The output signal The comparator can be used directly as a "false" or "real" control signal be used. It is also possible the comparator signal (usually a binary signal, i.e. For example, "1" for inside of the given DC voltage signal Measurement signal, otherwise "0") to control a to use sample / hold circuit. This can come from a (further) rectifier detector and the actual one sample / hold electronics made by the comparator is controlled. The former is that Comparator upstream rectifier detector on the input side connected in parallel. The possibly reinforced The output signal is then a (further) comparator to generate the "false" or "real" control signal fed.

The invention also relates to a method for testing of coins, being electromagnetic with a transmitter element Radiation is irradiated onto a coin the radiated electromagnetic radiation is reflected from the surface of the coin and being the reflected electromagnetic radiation caught with a receiver element and into one electrical measurement signal is converted, the Measurement signal supplied to an evaluation unit and with a predetermined comparison signal is compared, and according to the result of the comparison alternatively, a "false" control signal or a "real" control signal is generated and is characterized by that preferably the radiated electromagnetic Radiation has a line width Δλ / λ of less than 0.4 and that in the evaluation unit wavelength-selective evaluation signal, preferably in Area of the line width of the irradiated electromagnetic radiation, generated and with wavelength selective Comparison signal bands compared becomes. The above for the device according to the invention functional explanations made are on to apply the method according to the invention accordingly. In particular, it is preferred if the Line width less than 0.2, preferably less than 0.1, most preferably less than 0.07.

Fig. 1:

eine schematische Darstellung einer erfindungsgemäßen Vorrichtung,

Fig. 2a - 2d:

typische Eingangssignale für einen ein "falsch"- und "echt"-Steuersignal erzeugenden Komparator und

Fig. 3:

eine gegenständliche Ausführungsform von Senderelement und Empfängerelement.

In the following the invention will be explained with reference to drawings showing only one embodiment. Show it:

Fig. 1:

1 shows a schematic representation of a device according to the invention,

2a-2d:

typical input signals for a "false" and "real" control signal generating comparator and

Fig. 3:

a physical embodiment of the transmitter element and receiver element.

1 schematically shows an inventive Device for coin recognition. This Device is usually part of a usual Coin counter or / or coin sorting machine set up his. These machines are well known. For the Understanding of Fig. 1 is only important to know that isolated coins with such machines and driven past facilities by means of transport devices be what coins to recognize in the Location. In the context of such machines are wrong Coins that are not of a given coin type belonging coins sorted out and collected separately. 1 shows a transmitter element 1 for electromagnetic radiation, and a receiver element 2 for electromagnetic radiation, with which according to the irradiated on it Radiation an electrical measurement signal can be generated. The transmitter element 1 is a luminescent diode, which shines yellow or orange. Hereby can be special good brass or bronze colored coins 4 detect. The receiver element 2 is a phototransistor.

3 that the arrangement the transmitter element 1 and the receiver element 2 with the proviso that the transmitter element 1 radiated electromagnetic radiation 3 a coin 4 brought into a test position shines and that the reflection radiation emitted by the coin 4 5 radiates onto the receiver element 2. The Sender element 1 and the receiver element 2 are in the individual aligned so that the directions are maximum Radiation intensity as well as maximum sensitivity each at an angle of 15 ° to the Normals stand on a main coin surface 13.

In Fig. 1 it can also be seen that a with the receiver element 2 connected electronic Evaluation unit 6 is provided, by means of which after Provided a comparison of that of the receiver element 2 generated and processed into an evaluation signal 12 electrical measurement signal with a predetermined comparison signal 7 alternatively a "false" control signal or a "real" control signal can be generated. In order to a modulated luminescent diode is irradiated, is the measurement and evaluation signal, after demodulation, wavelength selective. In the evaluation unit 6 the control signals according to a comparison of the wavelength-selective evaluation signals 12 with predetermined Wavelength-selective comparison signal bands 7 generated. In particular, the transmitter element 1 has one Oscillator 8 for modulating the emitted electromagnetic Radiation 3. The evaluation unit 6 comprises an AC amplifier 9 for amplification the measurement signal, preferably with a filter, a detector 10 for demodulating the measurement signal, preferably a rectifier, and a DC amplifier 11 to reinforce the demodulated Signals and one in Fig. 1 of clarity for the sake of comparison, not shown, for comparison of the demodulated evaluation signal 12 with a predetermined one DC voltage range (7). Here it should be noted that in the embodiment shown Output signal of the DC voltage amplifier 11 is not immediately forms the evaluation signal 12. Rather it will this output signal for controlling a comparator used, which in turn a combination 14 one (another and the above detector 10 detector connected in parallel on the input side) and controlled by a sample / hold electronics. The output signal the sample / hold electronics, if necessary after DC voltage amplification, the evaluation signal 15.

2 are various evaluation signals 12 and specific comparison signal bands for a specific coin type 7 shown. Fig. 2a shows the Signals for a real mono coin, since that Evaluation signal 12 after "catching" the sample / hold electronics is in the comparison signal band 7. A downstream one Comparator then produces a "real" control signal. Has become below that according to FIG. 2a Checking coin type is a wrong coin or coin mixed with another variety, for example Evaluation signal 7 according to FIG. 2b obtained with the consequence of a "false" control signal. With the invention Device can also be bicolor coins check as can be seen in Figures 2c and 2d. Here the explanations given for FIGS. 2a and 2b apply corresponding. In the embodiment while checking the outer part of the coin switched off.

Claims (12)

Device for coin recognition, with a transmitter element (1) for electromagnetic radiation, with a receiver element (2) for electromagnetic radiation, with which an electrical measurement signal can be generated in accordance with the radiation irradiated thereon, the arrangement of the transmitter element (1) and the receiver element ( 2) with the proviso that electromagnetic radiation (3) emitted by the transmitter element (1) radiates onto a coin (4) brought into a test position and that at least part of a reflection radiation (5) emitted by the coin (4) of the radiated electromagnetic radiation (3) onto the receiver element (2), and with an electronic evaluation unit (6) connected to the receiver element (2), by means of which an evaluation signal (12 ) processed electrical measurement signal with a predetermined comparison signal (7) al alternatively, a "false" control signal or a "real" control signal can be generated,
characterized, that a wavelength-selective measurement and evaluation signal (12) can be generated in the receiver element (2) and the evaluation unit (6), and that the control unit can be generated with the evaluation unit (6) in accordance with a comparison of the wavelength-selective evaluation signal (12) with predetermined wavelength-selective comparison signal bands (7). Device according to claim 1, characterized in that with the transmitter element (1) electromagnetic Radiation can be radiated selectively and / or with the receiver element (2) electromagnetic Radiation selectively recordable is. Device according to claim 1 or 2, characterized in that that the transmitter element (1) is a luminescent diode having. Device according to one of claims 1 to 3, characterized in that the transmitter element (1) several wavelength-selective transmitter units has, the radiation spectra of Transmitter units are not overlapping and that in Receiver element (2) separate, one each Assignable measurement signals can be generated from the transmitter unit. Device according to one of claims 1 to 4, characterized in that the transmitter element (1) two luminescent diodes with different band gaps having. Device according to one of claims 1 to 5, characterized in that the transmitter element (1) for the emission of modulated electromagnetic Waves is set up. Device according to one of claims 1 to 6, characterized in that the receiver element (2) a photoresistor, a pn photodiode, a pin photodiode, an avalanche photodiode or has a phototransistor. Device according to one of claims 1 to 7, characterized in that the transmitter element (1) and the receiver element (2) are aligned that the directions of maximum radiation intensity and maximum sensitivity are the same or different at an angle of 0 - 50 °, preferably 5 - 30 °, most preferably 14 - 16 °, for Stand normals on a main coin surface (13). Device according to one of claims 1 to 8, characterized in that the transmitter element (1) an oscillator (8) for modulating the radiated has electromagnetic radiation (3), and that the evaluation unit (6) one AC voltage amplifier (9) for amplifying the Measurement signal, preferably with a filter, a detector (10) for demodulating the measurement signal, preferably a rectifier, and a DC amplifier (11) to reinforce the demodulated Signal and a comparator for comparing the demodulated Evaluation signals (12) with a predetermined DC voltage range (7). Method for checking coins (4), electromagnetic radiation (3) being radiated onto a coin using a transmitter element (1), the radiated electromagnetic radiation (3) being reflected by the surface of the coin (4) and the reflected electromagnetic radiation Radiation (5) is collected with a receiver element (2) and converted into an electrical measurement signal, the measurement signal being fed to an evaluation unit (6) and compared with a predetermined comparison signal, and alternatively a "wrong" according to the result of the comparison - Control signal or a "real" control signal is generated,
characterized, that in the evaluation unit (6) a wavelength-selective evaluation signal (12) is generated and compared with wavelength-selective comparison signal bands (7). A method according to claim 10, characterized in that the line width is less than 0.2, preferably less than 0.1, most preferably less than 0.07. A method according to claim 10 or 11, characterized characterized in that a device according to a of claims 1 to 9 is used.

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