ES2621612T3 - Currency selection system and method - Google Patents

Abstract

Coin selector system that has a coin raceway (6) configured to define a raceway of a coin (10) between: an inlet (3) to the raceway (6) where a coin ( 10) introduced begins a journey along the raceway (6); and an end (4) of the raceway (6) where a coin (10) leaves the raceway (6) once it has traveled the raceway; the system comprising: a light signal emitting element (1), configured to emit an incident light signal on a coin edge (10) and generate a reflected light signal; a light signal receiving element (2), configured to receive a light signal reflected by the edge of the coin (10); processing means of the reflected reflected signal to obtain a plurality of parameters from said signal and compare said parameters with corresponding parameters established for valid currencies to determine if the currency is valid; where the emitting element (1) and the receiving element (2) are located on a line substantially parallel to the raceway (6) at a minimum distance from the raceway (6) greater than the diameter of the largest coin admissible; characterized in that the emitter (1) and the receiver (2) are arranged and configured and have a radiation pattern such that: the distance between emitter (1) and receiver (2) is greater than the diameter of the smallest admissible currency; the axes (E) of maximum radiation of the transmitter (1) and of maximum sensitivity of the receiver (2) are perpendicular to the rolling ramp (6) so that there is no significant direct coupling between the transmitter (1) and the receiver ( 2) without the presence of a coin (10) in the analysis zone, the analysis area of the equivalent currency being at least the distance between the issuer (1) and the receiver (2); the emitter (1) and the receiver (2) have a radiation diagram approximate to the cosine law so that a substantially flat response of the coupling between emitter (1) and the emitter is obtained, due to the light signal reflected by the song of the coin (10), during the whole tour of the analysis area.

Description

image 1

DESCRIPTION

Currency selection system and method

Object of the invention

The object of the present invention is a system that verifies the validity of coins, tokens or in

5 general, discoid elements by analyzing the singing of said element. The present invention solves the analysis of the song of the coin in a simple and economic way, being able to incorporate in the coin selectors as an additional sensor in combination with other sensors dedicated to the analysis of other characteristics, such as diameter and electrical and mechanical characteristics of the alloy .

Field of the invention.

The present invention is encompassed within the devices that prove the validity of coins, tokens or other discoid elements. To differentiate the valid elements from those that are not, these devices determine different properties thereof, such as, for example, their dimensions, electromagnetic properties, electrical properties, weight, hardness, coinage, among others.

Background of the invention.

In the current state of the art, a wide range of sensors are used for the determination of the different properties of coins, tokens or discoidal elements, such as optical, magnetic, piezoelectric or acoustic sensors that are processed by means electronics ready for this purpose.

Commonly used are systems that measure the dimensions of coins by optical procedures, and those that determine alloy properties related to electrical conductivity and

20 magnetic permeability, using one or more electromagnetic sensors. Other optical procedures are related to the examination of the stamping or embossment of the coins, some aimed at analyzing the faces of the coins and others of the edge or edge of the coins.

There are numerous examples of sensors that examine the stamping of coin faces normally based on CCD type image sensors. These systems have the problem that they exist

25 many different prints or images for the same coin, which complicates its identification extraordinarily. In addition, the sensor and associated electronics are expensive, limiting the possibilities of use.

On the other hand, the examination or identification of the song of the coin requires simpler and cheaper means. As examples of this, the following documents are in the current state of the art:

30 Thus, for example, document GB2071381 describes an optical sensor for the song of the coins composed of a pair of emitter-receiver whose optical beams are directed towards the coin, coinciding in its singing. Part of the emitted light is reflected by the coin and reaches the sensor. Depending on the intensity of light received, the current currency will be accepted or rejected. This system has the disadvantage that only a small arc of the coin's total edge is analyzed.

35 A similar provision for the analysis of the edge of the coins can be seen in document EP0416932, which presents the same problem described above.

Other examples can be seen in documents DE3335347, which examines the edge of the coin with an arrangement of sensors contained in a plane perpendicular to the passage of the coin, while in the previous case it was parallel. As in the previous case, only a small one will be analyzed

40 part of the total periphery of the coin.

Document WO09106072A1 describes a device for analyzing the edge of the coin consisting of lighting the edge by a parallel beam of light, which illuminates the edge of the coin laterally. On the vertical of the raceway there is a detector that has previously been interposed a focusing lens and a grid coinciding with the passage of the edge of the valid coin to be detected. With this arrangement, the sensor will only give a valid signal when the valid diameter of the coin (by the focusing lens) coincides and when the singing model also coincides. This sensor also presents the same problem as the previous inventions, since the analysis of the song is performed in a small arc.

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Another problem that arises is that the sensor is valid only for one type of currency (diameter and specific edge), so it would be necessary to include as many specific sensors as types of coins to be validated.

In general, the effect produced by the analysis of a small part of the 360 degrees of the edge of the coin is that it is not possible in many cases to distinguish a coin with interrupted knurling from a smooth or continuous knurling and polygonal coins from the circular. It is also not possible to distinguish coins with angularly spaced inscriptions, as is the case of the “Spanish flower” (such as € 0.20 coins) or embossed motifs of an important angular size or separation.

To solve the problem described and widen the analysis of the currency edge, some solutions have been developed that are detailed below:

The device of WO09106072A1, uses several photoreceptors oriented at different angles of the coin increasing the area of analysis. This solution, besides being expensive, has the disadvantage of the space required for its implementation.

WO09744760A1 describes an optical system based on a laser light source and an optics that illuminate the coin along a vertical and perpendicular line with respect to the raceway. On the opposite side there is a linear sensor in an upright position. The coin partially interrupts the beam and casts the shadow of the edge over the sensor. This allows to analyze a more important area of the edge of the coin, but with the disadvantage of the high cost of the emitter, optics and sensor set, which makes it unfeasible in many applications.

WO00043961A1 describes another form of song analysis. In this case the emitter is a source of collimated laser light to achieve a beam of rectangular section and stable with distance. The result is an accurate analysis of a wide area of the edge of the coin, but it has the disadvantage that the light source must be located on one side of the raceway, being a problem of difficult solution in devices of small size. In addition, the light source is expensive and not very robust in applications where a wide range of temperatures or adverse environmental conditions is required.

GB2071381A describes a coin testing device to discriminate between circular coins of substantially the same size but with different singing characteristics. However, said invention is only capable of differentiating coins with different reflectivity in its edge, but it is not capable of distinguishing coins with different periodic patterns or different slot sizes, nor differentiating circular coins from polygonal coins. In addition, you cannot distinguish periodic patterns (stamped on the edge of the coin) with a large distance between patterns.

Description of the invention

To alleviate the aforementioned problems, the system according to claim 1 is presented.

All this in such a way that there is no significant direct coupling between the sender-receiver without the presence of a currency, while there will be a coupling thanks to the interposition of the singing of a coin.

In order for this coupling to materialize during an important coin path, said emitting and receiving elements shall be located on a line substantially parallel to the raceway and at a minimum distance greater than the diameter of the coin of the largest admissible size.

The separation between sender and receiver is an important feature, since it will define the area of the raceway where the edge of the coin can be examined. It is assumed, regardless of the size of the coin, that the area of analysis of the edge of the coin is equivalent, at least, to the distance between the two elements of the transmitter-receiver set. This feature allows the examined area of the edge of the coin to be much larger than those described in the prior art and mentioned above.

An important characteristic for the emitter and the receiver is that they must have a high beamwidth, since otherwise, by moving them away, there would be no optical coupling through the reflection of the edge of the coin. That is, the transmitter and the receiver must not incorporate optical concentrators. In addition, the emitters and receivers should have a radiation diagram approximate to the cosine law, that is, with a maximum (100% of the radiation emitted for the emitter or sensitivity for the receiver) on the front axle (0º) and a minimum of radiation (0%) on the side (90º). It is also very convenient for the transmitter to work in the infrared spectrum and for the receiver to be exclusively suitable for such infrared radiation, thereby

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that the effects of ambient light that could be introduced through slots inside the device are minimized.

Another important feature of the arrangement of the emitter and receiver is that the axis of maximum radiation and sensitivity respectively, are oriented towards the raceway of the coins, that is, that both are located parallel to each other and with the optical axes perpendicular to the Raceway. Under these conditions there will be no significant coupling between them in the absence of currency, and the defined radiation diagram allows the coupling with currency during the entire journey through the analysis area. In the absence of currency, there may be a small coupling due to the reflections of the raceway that do not significantly affect the quality of the signal received in the device of the invention, which can be considered as a controlled parameter in the assembly (offset) and that it can be discriminated against the signal provided by the sensor.

By properly choosing the separation between the sensors and the height on the raceway, it is possible for a wide range of coin diameters to achieve a low dependence on the signal level depending on the relative position of the coin relative to the sensor.

The system is completed with signal processing means, which in turn includes:

(i)

a first amplifier stage in the sensor;

(ii)

a second stage of control of the radiated intensity for the emitter; Y

(iii) signal processing means.

Where it is provided that said signal processing means are based on a microcontroller, and more specifically a microcontroller of the digital signal processor or DSP type. In addition, said signal processing means includes at least:

(i)

two filters; Y

(ii)

a shunt

The sensor thus described provides a very useful safety feature to discriminate authentic currencies from other fraudulent ones, or from interference from other valid currencies of other countries.

The system object of the present invention solves the problem of the analysis of a large area of the edge of the coin. For example, in a typical selector we can multiply by a factor between two and three the arc of the song analyzed by this system, compared to the known so far, getting to analyze more than 50% of the circumference of the edge of the coins.

Brief description of the figures.

A series of drawings that help to better understand the invention and that expressly relate to an embodiment of said invention which is presented as a non-limiting example thereof is described very briefly below.

Figure 1 schematically shows the arrangement of the sensors together with the trajectory of the light beams in different positions of the coin.

Figure 2 shows the block diagram associated with the optical sensor.

Figure 3 represents the type of radiation diagram used for the transmitter and receiver of the optical sensor of the invention.

Figure 4 shows the signal obtained at the sensor output with a coin with the prior art technology.

Figure 5 shows the signal obtained with the proposed solution under the same conditions as in the previous case.

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Figure 6 shows the output of the amplifier (12) for two coins of different reflectivity.

Figure 7 corresponds to the output of the amplifier (12) for a coin presenting details in high relief at its edge.

Figure 8 corresponds to the output of the amplifier (12) for a coin similar to that shown in Figure 7 5 but with the bas-relief details.

Figure 9 shows the output of the bandpass filter (13) for the coin of Fig. 7.

Figure 10 shows the output of the bandpass filter (13) for the coin of Fig. 8.

Figure 11 corresponds to the output of the amplifier (12) for a coin with polygonal edge.

Figure 12 shows the output of the amplifier (12) for a circular edge coin.

10 Figure 13 shows the output of the low pass filter (14) for the coin of Fig. 11.

Figure 14 corresponds to the output of the low pass filter for the coin of Fig. 12.

Figure 15 shows the output of the shunt (15) for the coin of Fig. 11.

Figure 16 shows the output of the shunt (15) for the coin of Fig. 12.

Preferred embodiment of the invention.

15 As can be seen in the attached figures, and especially in Figure 1, the system object of the present invention comprises at least one emitter (1) that is preferably positioned close to the inlet mouth (3) of the coins, while the receiver (2) is mounted in the position near the end (4) of the rolling ramp (6) and approximately the same distance from that track as the transmitter (1). The distance of the optical pair to the raceway (6) will be greater than the diameter of the larger coin. By

On the other hand, the distance between the transmitter (1) and the receiver (2) is:

-always greater than the diameter of the smallest admissible currency;

-preferably similar to the length of the track and rolling (6);

-or well close to the diameter of the largest admissible currency;

The axes (E) of maximum radiation / sensitivity of the emitter (1) and the receiver (2), must be oriented towards

25 the rolling ramp (6). In this way, the optical sensor of the edge of the coin will explore the edge of the coin throughout the journey through the measurement zone.

As an example of the improvement of the area of analysis of the currency, we can see in Figure 4 that represents the aforementioned prior art technology, the shape of the obtained signal has strong lateral slopes, while the useful duration of the signal is, at most, 70ms, which at a typical speed of 30 coins equals about 14mm of travel. In addition, the start and end areas of the mentioned signal are not very useful given their low level. By comparing this signal with that represented in Figure 5, the signal provided by the proposed sensor can be seen under the same conditions as the previous case. As can be seen in the signal, the level is much more constant and the useful signal has a duration of 180ms, which is equivalent to 36mm of coin travel, that is, more than double that in the previous case, with the advantage

35 that the signal is useful from the beginning to the end.

Returning to figure 1, in this figure the path of the light emitted by the emitter (1), which is reflected in the edge of the coin (10), represented in three different positions and reaches the receiver (2) is schematically represented. . As can be deduced from this assembly, the two components, emitter (1) and receiver (2), must have the characteristic of a beamwidth such that the coupling between the two is maintained, 40 when there is a coin in the rolling ramp ( 6). A typical diagram suitable for the proposed embodiment can be seen in Figure 3 in which the beam width, at 50%, is around ± 65 °. Given this diagram, a substantially flat response of the coupling between emitter (1), currency is obtained

(10) and receiver (2), for a range of commonly used coin diameters (10). This feature

remarkably facilitates the extraction of the useful signal of the song of the coin, consisting of the variations of the

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signal with respect to a medium level, that is, the alternating modulating component that is superimposed on the average signal that is the value of the reflectivity of the coin. The alternate component that is appreciated, is due to the reflections produced by irregularities in the singing of the coins, which is the main characteristic that we intend to identify or recognize.

To optimize the results, it is convenient to use a current source (11) controlled by a microcontroller (16) to feed the emitter (1), which will preferably be a photodiode with infrared emission. To compensate for the thermal drift of the photodiodes, it is optionally possible to mount a temperature sensor, not shown, and close to the emitter (1), which may consist of a standard signal diode. Depending on the temperature it is possible to control the source of the transmitter's power supply (1)

or compensate the measure according to an inverse law to thermal variation. As for the receiving element (2) it is convenient that it is of the high sensitivity PIN photodiode type and with visible light filter (infrared transparent). The sensor output will be connected to the input of a current-voltage amplifier (transimpedance amplifier (12)) that has the advantage of using the receiver linearly (2) and optimizing the thermal behavior, as can be seen in the figure 2.

Additionally, the device may include optical barriers (7), (8) and (9) normally used to measure the diameter and position of the coin. This can be useful for analyzing the signals and relating them to the position of said coin (10) in the rolling ramp (6).

It is convenient to incorporate step-band filter media. In this way, the continuous and low frequency components disappear, leaving only the useful signal related to the fine details of the coin edge. Since the components to be filtered are unimportant, the filter is simple and it is sufficient, for example, a 2nd-order Butterworth band-band filter, which can be incorporated either by analog means, or by digital means, preferably using a structure microcontroller type digital signal processor or DSP.

The system object of the present invention further comprises a second filter, of the low-pass type, in such a way that the low frequency components related for example with the presence of interrupted knurls, reliefs, inclusions, or polygonal coins are removed. The filter output can be used directly or after passing through a shunt (15) that eliminates the DC component and defines more precisely the flanks and slopes of the signal representative of the transitions of the different areas of the coin's edge. .

The four signals, that is, the original signal plus the two filtered and the derivative of the second filter, are analyzed by the microcontroller (16) that calculates, for each of them, parameters such as average signal value, effective value ( RMS), maximum and minimum peak values, peak-to-peak value, numbers of zero crossings (transitions), Fourier transform, separation between peaks and statistical parameters such as standard deviation and variance. The calculation of the mentioned parameters can be done for the entire route of the coin (10) by the rolling ramp (6) or by sections. In this case, the optical barriers (7-9) are used to define an initial, a central and a final section.

In the system described in the present invention, the calculated parameters can be related to the instantaneous position of the coin, as for example as described in patent EP1391851 of the same applicant, thus being able to obtain data related to the actual separation of details detected in the song of the coin. Finally, the parameters obtained are compared with those established for valid currencies and, if acceptable, the microcontroller (16) will activate the intake gate (17) together with other communication signals with other devices, not shown, and otherwise the currency It will be rejected.

Examples 6 to 16 show some of the possibilities that the system presents in terms of coin discrimination based on the shape or details of the edge and its reflectivity. Thus, in figure 6 the outputs of two coins of identical shape and size but with different reflectivity in the edge are shown. This signal (12) is analyzed directly by the microcontroller (16) and parameters such as the average value of the signal or the minimum value may be sufficient to distinguish them from each other.

Another example of two similar currencies but with the difference of presenting one of them details in the high-relief and bas-relief song, we can see it respectively in Figures 7 and 8. Although the direct signal of the amplifier (12) can also be used directly, it is convenient to use the band pass filter (13), whose outputs are shown respectively in Figures 9 and 10. The microcontroller will calculate for example parameters such as effective signal value (RMS), maximum peak, minimum and peak to peak values , number of peaks that exceed a predetermined threshold, etc., being able to identify or discriminate currencies thanks to this characteristic. The calculation of the parameters can be done globally for the entire signal or as already mentioned by sections, or by calculating the size or separation of the detected details, thanks to the fact that with the same sensors it is possible to associate the signal to the position of the currency at every moment of time.

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5 A third example is shown in Figures 11 and 12, in which two coins of similar size and material are shown respectively, but the first one has a polygonal shaped edge, while the second one has it circular. Also in this case the signals can be used directly from the sensor (12), but it is more convenient to use those of the low pass filter output (14), which correspond to figures 13 and 14 and better still those of the output of the shunt (15), figures 15 and 16, which improves the analysis conditions of

10 signal, eliminating the continuous component and highlighting transitions better. As in the previous cases, the microcontroller will calculate parameters that will be used for coin discrimination based on the characteristics of its song.

Although the preferred embodiment is performed on a typical coin selector model in which the coins roll through the sensors, it can be incorporated into others of the free fall type, disc or

15 coin conveyor belt, among others.

Claims (14)

image 1 1. Coin selector system that has a coin raceway (6) configured to define a raceway of a coin (10) between: an inlet (3) to the raceway (6) where a coin (10) introduced begins a journey along the raceway (6); Y an end (4) of the raceway (6) where a coin (10) leaves the raceway (6) once it has traveled the raceway; the system comprising: a light signal emitting element (1), configured to emit an incident light signal on a edge of the coin (10) and generate a reflected light signal; a light signal receiving element (2), configured to receive a light signal reflected by the edge of the coin (10); processing means of the filtered reflected signal to obtain a plurality of parameters from said signal and compare said parameters with corresponding parameters set for coins 15 valid to determine if the currency is valid; where the emitting element (1) and the receiving element (2) are located on a line substantially parallel to the raceway (6) at a minimum distance from the raceway (6) greater than the diameter of the larger coin admissible; characterized in that the emitter (1) and the receiver (2) are arranged and configured and have a radiation pattern such that: the distance between sender (1) and receiver (2) is greater than the diameter of the smallest permissible currency; the axes (E) of maximum radiation of the emitter (1) and of maximum sensitivity of the receiver (2) are perpendicular to the rolling ramp (6) so that there is no significant direct coupling between the emitter (1) and the receiver ( 2) without the presence of a coin (10) in the analysis area, the analysis area being the edge of 25 the equivalent currency, at a minimum, at the distance between the sender (1) and the receiver (2); the emitter (1) and the receiver (2) have a radiation diagram approximate to the cosine law so that a substantially flat response of the coupling between emitter (1) and the emitter is obtained, due to the light signal reflected by the song of the coin (10), during the whole tour of the analysis area. 2. System according to claim 1, characterized in that the distance between emitter (1) and receiver (2) is substantially equal to the length of the raceway (6).

3.

System according to claim 1, characterized in that the distance between emitter (1) and receiver (2) is close to the diameter of the largest admissible coin.

Four.

System according to any of the preceding claims, characterized in that the emitting element (1)

It has a radiation diagram with a maximum of 100% of radiation on the front axle (E) and a minimum of 0% of radiation on the side. System according to any of the preceding claims, characterized in that the receiving element (2) has a radiation diagram with a maximum of 100% sensitivity on the front axis and a minimum of 0% sensitivity on the side. 6. System according to any of the preceding claims, characterized in that the emitting element (1) 40 is a photodiode with emission in the infrared spectrum.

7.

System according to any of the preceding claims, characterized in that the receiving element (2) is a PIN photodiode having a visible infrared transparent light filter.

8.

System according to any of the preceding claims, characterized in that it comprises a plurality of optical barriers (7-9) for measuring the diameter and position of the coin to calculate parameters of the reflected signal associated with the position of the coin.

9.

System according to any of the preceding claims, characterized in that the signal processing means comprise at least:

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(i)

logical means of signal processing (16);

(ii)

a current source (11) of the emitting element (1);

(iii) amplifying means (12) of the signal of the receiving element (2);

(iv)

step-band filter means (13);

(v)

low-pass filter media (14); Y

(saw)

signal derivative means (15);

such that the signal processing means (16) govern the current source (11) of the emitting element (1) and also receive the signals from the filters (13, 14), the shunt (15) and the amplified signal (12) of the receiving element (2).

10.

System according to any of the preceding claims, characterized in that it comprises a temperature sensor for detecting the thermal drift of the emitting element (1).

eleven.

System according to claims 9 or 10, characterized in that the signal amplifying means (12) comprise a transimpedance amplifier.

12.

System according to any of the preceding claims, characterized in that any of the pass-band, low-pass and bypass filtering means are implemented in a form selected from:

- analog implementation with dedicated circuitry; - digital implementation in the logical means of signal processing (16).

13.

System according to any of the preceding claims, characterized in that the signal processing means (16) comprise a digital signal processor type DSP.

14.

System according to any of the preceding claims, characterized in that the parameters obtained from the filtered reflected signal comprise at least one of the following: - average value of the signal; -effective value; -value peak peak; - minimum peak value; -value peak to peak; -number of peaks that exceed a predetermined threshold; -number of steps by zero;

-Fourier transform; -separation between peaks; 9 image3 -type deviation and variance. 10