JP2000011229A - Method and device for coin discrimination - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coin discrimination method and device therefore which can surely discriminate a clad coin from any other coins and is highly reliable. SOLUTION: This device consists of exciting coils 20 and 21 and an eddy current loss detection type magnetic sensor 100 of a coil structure which has a reflection detection coil 23 on the same side as a detection object coin. Here, the exciting coils 20 and 21 are excited by synthesizing of, at least, more than three kinds of plural frequencies, an output difference of the reflection detection coil 23 when there is or is not a coin in each of the frequencies is divided by an output when there is no coin, a rate of attenuation is obtained and the coin is discriminated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is suitable for a coin processing machine such as a coin sorter, a coin depositing machine, a coin wrapping machine and the like, and has a very reliable coin type and authenticity. High coin identification method and apparatus.

[0002]

2. Description of the Related Art As a prior art, there is a coin discriminating apparatus as disclosed in Japanese Patent Publication No. 2567654. This coin discriminating device excites an oscillation coil at a high frequency and a low frequency, and obtains a sum of output attenuation at each frequency output from a receiving coil, thereby forming a clad coin (bimetal coin) having the same surface material as a single-piece structure. The coins are identified based on the fact that different outputs are obtained from the coins.
Here, the clad coin is a coin having a three-layer structure made of different materials such as aluminum (Al) or copper as a core material and white copper (CuNi) layered on both surfaces as shown in FIG. The output level of the signal is different between the output of a normal white copper coin and the output of a clad coin whose surface is only white copper.

[0003]

However, the above-mentioned conventional apparatus has a disadvantage that clad coins cannot be reliably identified. This is because there may be other single-material coins having the same output level as that of the clad coin whose surface is made of white copper.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a highly reliable coin discriminating method and a highly reliable coin discriminating method capable of reliably discriminating a clad coin from any coin. It is to provide a device.

[0005]

SUMMARY OF THE INVENTION The present invention relates to a coin discrimination (method and apparatus), and an object of the present invention is to provide an eddy current having a coil configuration in which an exciting coil and a reflection detecting coil are on the same side of a coin to be detected. It consists of a loss detection type magnetic sensor, excites the excitation coil by synthesizing at least three or more types of multiple frequencies, and divides the output difference of the reflection detection coil when there is a coin at each frequency by the output when there is no coin. This is achieved by obtaining an attenuation rate, or by further normalizing the attenuation rate at each frequency by dividing by an attenuation rate at a specific frequency so as to identify the coin. This is more effectively achieved by further identifying the coin based on the output of the transmission detection coil provided opposite the excitation coil and the reflection detection coil.

[0006] The object of the present invention is to provide at least 3
An exciting coil that is excited by synthesizing a plurality of different frequencies,
A reflection detection coil wound around the same core as the excitation coil, separation means for separating the plurality of frequency components from the output of the reflection detection coil, and the plurality of frequency components separated by the separation means; The output difference of the reflection detection coil in the presence or absence of a coin at each of the frequencies is divided by the output without the coin to obtain an attenuation rate, or the attenuation rate at each of the frequencies is normalized by dividing by the specific attenuation rate at the frequency. This is achieved by providing identification means for identifying the coin, wherein the separation means comprises a band-pass filter, a full-wave rectifier circuit, a low-pass filter, and an A / D converter, and the identification means is operated by a digital value. This is achieved more effectively.

Further, the above object of the present invention is to provide at least three objects.
An exciting coil that is excited by synthesizing a plurality of different frequencies,
The reflection detection coil wound around the same excitation core as the excitation coil, the transmission detection coil wound around the detection core facing the excitation core, and the component of the plurality of frequencies separated from the output of the reflection detection coil Separating means, and by the components of the plurality of frequencies separated by the separating means, while obtaining the attenuation rate by dividing the output difference of the reflection detection coil when there is a coin at each frequency by the output when there is no coin,
This is achieved by providing an identification means for detecting the outer shape of the coin based on the output of the transmission detection coil and identifying the coin.

[0008]

FIG. 1 shows a magnetic sensor 100 according to the present invention.
The transmission detection coil 11 is wound around a plate-shaped detection core 10 as shown in FIG.
The transmission detection coil 11 outputs a detection signal DT1. An exciting coil 21 is wound around a plate-shaped exciting core 20 having a notch at two central portions on the upper side as shown in FIG. A reflection detection coil 23 is wound around the projection 22, and a detection signal D is output from the reflection detection coil 23.
T2 is output. Magnetic sensor 100
A passage 1 through which a coin to be detected is conveyed and passed is provided at the center of the eddy current sensor, and an excitation coil 21 and a reflection detection coil 23 form an eddy current loss type magnetic sensor. This detection is called reflection detection in the present invention. Name. The excitation coil 21 is excited by an excitation power supply 30, and a detection signal D is transmitted from the transmission detection coil 11.
At T1, the reflection detection coil 23 outputs a detection signal DT2. FIG. 3 shows that a transmission detection coil 11 is wound around a detection core 10, and an excitation coil 21 is
The reflection detection coils 23 are respectively wound around the protrusions 22.

FIG. 4 shows a permalloy shield plate 12.
And 24 are mounted outside the detection core 10 and the excitation core 20, and the shield plates 12 and 24 block external magnetism. Further, the magnetic sensor 100 of the present invention is disclosed in Japanese Patent Application Laid-Open No. 9-7356 by the present applicant.
As shown in FIG. 5, a passage 1 made of a wear-resistant material 2 is formed between the upper and lower sensor portions by molding (3) as shown in FIG. An excitation core 20 is provided under the sensor molded into a U-shape.
(The excitation coil 21 and the reflection detection coil 23) are housed therein, and the detection core 10 (the transmission detection coil 11) is housed above the molded rectangular sensor. The sensor case is made of ceramic, PPS resin, or the like, and the lower part of the sensor and the upper part of the sensor are detachable by, for example, screws. FIG. 6 shows a coin detection state of the magnetic sensor 100, in which the coin 200 passes through the passage 1 by the transport belt 4, and during this passage, the coin 200
Is to be identified.

FIG. 7 shows an example of the excitation power supply 30 of the magnetic sensor 100 and a detection circuit (reflection detection). The excitation power supply 30 includes four oscillators 31, 32, 3 having different oscillation frequencies.
3 and 34, and each frequency (in this example, 2 KHz, 10 K
Hz, 50 KHz, and 200 KHz) are added and amplified by the addition amplifier 35, and the driving circuit 36
To excite the exciting coil 21 of the magnetic sensor 100 via the. The detection signal DT2 output from the reflection detection coil 23 of the magnetic sensor 100 is input to four kinds of bandpass filters (BPF) 41, 42, 43, and 44 via the amplifier 40, and is separated into the above-mentioned respective frequency components. The signals separated into the respective frequency components are respectively applied to the full-wave rectifier circuits (5
1,52,53,54) and low-pass filter (LP
F) The DC level is passed through (61, 62, 63, 64) and further through A / D converters (71, 72, 73, 74), and digital detection signals SG1, SG2, SG3, SG4
Is output as The detection signals SG1, SG2, SG3,
SG4 is input to the operation identification means described later to identify coins. Also, the detection signal D from the transmission detection coil 11
T1 is also input to the identification means, and is used to detect the outer shape (diameter) of the coin. In this example, four kinds of frequencies are used, but three kinds of frequencies may be used.
Hz, 10 KHz, and 50 KHz.

An operation example of the above configuration will be described. FIG. 8 and FIG. 9 show waveform examples of the excitation signal and the detection signal. Here, for simplicity, description is made with two kinds of frequencies.

FIG. 8 shows a process from the excitation of the magnetic sensor 100 by combining a plurality of frequencies to the separation of the frequency component of the detection signal. FIG. 8A shows a low-frequency excitation signal. B) shows a high frequency excitation signal. The plurality of excitation signals are combined by the addition amplifier 35 and applied to the excitation coil 21 of the magnetic sensor 100 via the drive circuit 36. Accordingly, the combined signal applied to the exciting coil 21 is as shown in FIG. The detection signal DT2 output from the reflection detection coil 11 of the magnetic sensor 100 is as shown in FIG. 8D, and has a waveform corresponding to the excitation signal.
44, where only low-frequency signals such as those shown in FIG. 11E are extracted according to each band-pass frequency. Here, the synthesis and separation of two types of frequency signals are described, but the same applies to the case of four types.

On the other hand, FIG. 9 shows an example of processing of a high-frequency signal after frequency separation of the detection signal DT2 from the magnetic sensor 100. FIGS. 9 (F), 9 (G) and 9 (H) show no coins. The waveform example at the time (standby) is shown in FIG.
(J) and (K) show waveform examples when a coin is present (during detection). 9 (F) and 9 (I) show examples of output waveforms from the band-pass filters (41-44), respectively, and FIGS. 9 (G) and 9 (J) show full-wave rectifier circuits (51-54), respectively. (H) and (K) show examples of output waveforms of the low-pass filters (61-64), respectively. Output signals indicated by (H) and (K) in FIG. 9 are converted into digital detection signals (SG1-SG4) by A / D converters (71-74) and used for coin identification by the identification means. You. Here, FIG. 9 (K ′) is an enlarged view of the vertical axis of FIG. 9 (K). When the output signal level at the time of standby is a and the minimum value of the output signal level at the time of detection is b, the output attenuation by coins The value obtained by normalizing (ab) with the output signal level a during standby is an attenuation rate (= (ab)
/ A), which is a feature amount of coin identification. The identification means identifies the coin based on the standardized value. Although the output signal level varies due to the variation in the magnetic sensor 100 and the signal processing circuit, the signal variation can be absorbed by normalizing the output signal level a as described above. The discriminating means compares each feature value with a judgment frame provided in advance for each coin to discriminate the authenticity of the coin.

FIG. 10 shows three-layer coins and A coins of a monometal structure (single structure) of Al coin and CuNi coin, and a bimetal structure (cladding structure) of CuNi / Al / CuNi.
An example of an attenuation rate by reflection detection (detection signal DT2) of a coin having four types of structures, including a three-layer coin of l / CuNi / Al, is shown. The coin has a diameter of 26 mm and a thickness of 2 mm. In the case of a clad structure, the thickness of each of the front and back layers is 0.5 m.
m, the thickness of the intermediate layer is 1 mm. Although FIG. 10 experimentally shows a plot with six types of frequencies, the identification device does not need to have six types of frequencies. Here, the attenuation rate is determined by the material of the surface layer at a high frequency, and is affected by the material of the intermediate layer at a low frequency. Therefore, the above four frequencies (2 KHz, 10 KHz, 50 KHz, and 200 KHz)
The four types of coins can be identified by comparing the decay rate in the above with a predetermined criterion. still,
If the decay rate changes with temperature, see Japanese Unexamined Patent Publication No. 9-73.
As described in Japanese Patent No. 568, the ambient temperature may be detected by temperature detection utilizing a change in electric resistance due to the temperature of the exciting coil, and correction may be made based on the ambient temperature. FIG.
Shows an example of the attenuation rate based on the detection of penetration (detection signal DT1) of coins having the four types of structures shown in FIG. In the case of transmission detection, the two types of cladding structure cannot be distinguished because the output attenuation factor does not depend on the order of the layers.

FIGS. 12 and 13 show examples of attenuation factors by reflection detection and transmission detection of a coin having a ferromagnetic material sandwiched in the second layer. In FIG. 12, when a ferromagnetic material is sandwiched in the second layer, the output increases without attenuating in a low frequency range (comes into a negative region), and thus it can be seen that the ferromagnetic material is used. In FIG. 13, even when the ferromagnetic material is sandwiched between the second layers, the output in the low frequency range is attenuated (the positive region in the figure), so it cannot be understood that the ferromagnetic material is detected only by transmission detection. .

As described above, the transmission detection cannot detect the difference in the order of the layers of the clad-structured coins and the ferromagnetic material.
This is possible with reflection detection. In reflection detection, when a coin floats during transport, the attenuation rate decreases, so the judgment frame (threshold) must be widened to cope with the coin float, but this reduces the accuracy of identification. Become. In order to identify coins without lowering the accuracy, the coins may be identified by a standard value obtained by dividing the attenuation rate at each frequency by the attenuation rate at an arbitrary frequency.
Furthermore, instead of discrimination at discrete frequencies as described above, the continuous output level for each frequency when the excitation frequency is swept during standby is stored, and the excitation frequency is stopped by stopping coins on the magnetic sensor. By performing a sweep and calculating the detected continuous output level for each frequency, a continuous attenuation rate waveform for each frequency may be obtained, and identification may be performed based on this waveform shape.

FIG. 14 shows a modified example (100A) of the magnetic sensor used in the present invention. In order to easily install the belt 4 for transporting coins through the passage 1, the detection core 2 is provided.
The transmission detection coils 11A and 11B are wound around the two divided cores.

When the above-described reflection detection is combined with transmission detection (for example, an attenuation rate at 200 KHz) for detecting a diameter (outer shape), coin identification accuracy is further improved. Further, in order to stabilize the signal, a preamplifier may be built in the magnetic sensor.

[0019]

As described above, according to the coin identification method and apparatus of the present invention, not only the material of the coin but also the layer structure can be detected, so that the authenticity identification of the coin is further improved. Therefore, it is possible to reliably identify the clad coin.

[Brief description of the drawings]

FIG. 1 is a connection structure diagram schematically illustrating an example of a magnetic sensor used in the present invention.

FIG. 2 is an arrangement structural view showing an example of a detection core and an excitation core used for a magnetic sensor.

FIG. 3 is a diagram showing how a transmission detection coil, an excitation coil, and a reflection detection coil are wound around a detection core and an excitation core.

FIG. 4 is a diagram showing an example of the arrangement of a shield plate provided on a magnetic sensor.

FIG. 5 is an external configuration diagram of a magnetic sensor.

FIG. 6 is a state diagram showing a state of coin recognition by a magnetic sensor.

FIG. 7 is a block diagram illustrating a circuit configuration example of the coin identification device of the present invention.

FIG. 8 is a waveform chart showing an operation example of the present invention.

FIG. 9 is a waveform chart showing an operation example of the present invention.

FIG. 10 is a diagram illustrating a characteristic example of reflection detection.

FIG. 11 is a diagram illustrating a characteristic example of transmission detection.

FIG. 12 is a diagram illustrating a characteristic example of reflection detection.

FIG. 13 is a diagram illustrating a characteristic example of transmission detection.

FIG. 14 is a connection structure diagram showing another example of the magnetic sensor of the present invention.

FIG. 15 is an external view showing an example of a clad coin.

[Explanation of symbols]

 Reference Signs List 1 passage 10 detection core 11 transmission detection coil 20 excitation core 21 excitation coil 23 reflection detection coil 100, 100A magnetic sensor 200 coin

Claims (7)

[Claims] 1. An eddy current loss detection type magnetic sensor having a coil configuration in which an excitation coil and a reflection detection coil are on the same side of a coin to be detected, and exciting the excitation coil by combining at least three or more types of plural frequencies. The coin discrimination method is characterized in that the output difference of the reflection detection coil in the presence or absence of a coin at each of the frequencies is divided by the output in the absence of a coin to obtain an attenuation rate to identify the coin. 2. An eddy current loss detection type magnetic sensor having a coil configuration in which an excitation coil and a reflection detection coil are on the same side with respect to a coin to be detected, and exciting the excitation coil by synthesizing at least three or more types of plural frequencies. Then, the output difference of the reflection detection coil when there is a coin at each frequency is divided by the output at the time of no coin to obtain an attenuation rate, and the attenuation rate at each frequency is normalized by dividing by the attenuation rate at a specific frequency. A coin identification method, wherein a coin is identified. 3. The coin identification method according to claim 1, wherein the coin is further identified based on the output of a transmission detection coil provided opposite to the excitation coil and the reflection detection coil. 4. An excitation coil which is excited by synthesizing at least three or more types of plural frequencies, a reflection detection coil wound around the same core as the excitation coil, and an output of the reflection detection coil which detects the plural frequencies. Separation means for separating components,
According to the components of the plurality of frequencies separated by the separating unit, the output difference of the reflection detection coil in the presence or absence of a coin at each frequency is divided by the output in the absence of a coin to obtain an attenuation rate, and the coin is identified. A coin identification device, comprising: identification means. 5. An excitation coil which is excited by synthesizing at least three or more types of plural frequencies, a reflection detection coil wound around the same core as the excitation coil, and an output of the reflection detection coil which detects the plural frequencies. Separation means for separating components,
According to the components of the plurality of frequencies separated by the separating unit, an output difference of the reflection detection coil when there is a coin at each frequency is divided by an output when no coin is present to obtain an attenuation rate, and an attenuation rate at each frequency is obtained. And a discriminating means for discriminating the coin by dividing and standardizing the coin by an attenuation factor at a specific frequency. 6. The apparatus according to claim 4, wherein said separating means comprises a band-pass filter, a full-wave rectifier circuit, a low-pass filter, and an A / D converter, and said discriminating means operates on a digital value. The coin identification device according to the above. 7. An exciting coil excited by combining at least three or more types of plural frequencies, a reflection detecting coil wound around the same exciting core as the exciting coil, and a winding wound around a detecting core facing the exciting core. The rotated transmission detection coil, separation means for separating the plurality of frequency components from the output of the reflection detection coil, and the plurality of frequency components separated by the separation means, the presence or absence of a coin at each frequency. The output difference of the reflection detection coil is divided by the output when there is no coin to obtain the attenuation rate, and the outer shape of the coin is detected by the output of the transmission detection coil to identify the coin. A coin identification device characterized by the above-mentioned.