JPS5856154B2 - coin sorting device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a coin sorting device that detects changes in the magnetic field based on changes in the phase of signals by placing a coin in a magnetic field that generates an alternating magnetic field to determine the type and authenticity of the coin. The purpose is to provide a coin sorting device that can sort coins with high precision.

Although this method of determining test coins by examining their magnetic properties is an extremely effective method, if a counterfeit coin that happens to exhibit approximately the same change in magnetic field at the frequency of the alternating magnetic field is inserted, it may be mistaken. There was a problem with the sorting process.

Figure 1 shows the experimental results when changes in the magnetic field are viewed in terms of phase. The logarithmic axis of the horizontal axis shows the frequency, and the vertical axis shows the voltage induced by an exciter such as an excitation coil and the voltage induced by an exciter such as a detection coil. The phase difference with the voltage detected by the detector is taken to determine the magnetic property A of the cupronickel and copper clad coin, which is a genuine coin, and the magnetic property B and A property Q of a silver coin, which is also a genuine coin. The magnetic properties C of a thin copper counterfeit coin and the magnetic properties C of a genuine cupronickel coin are shown.

From this experimental result, it can be seen that each of the magnetic properties A, B, C, and D intersects with any one of the magnetic properties.

In other words, the same phase difference occurs at these frequencies, which causes erroneous selection.

Based on these experimental results, the conventional sorting device
, B, C, and D intersect (for example, around 4KC under the conditions of this experiment).

However, when coins pass randomly through the coin passage pile, the distance between the coin surface and the detection coil is not always constant, and the distance is different every time an inspection is performed.

Figure 2 shows some interesting experimental results.
Although measurements were taken under the same conditions as in the figure (i.e., the same excitation coil and detection coil were used), the distance between the detection coil and the coin surface was set to 0 mm in Figure 1, whereas this distance was measured at 2 mm. The experiment was conducted using

Comparing these two figures, it must be mentioned that not only the phase difference is generally low, but also that the intersections of the magnetic characteristics A, B, C, and D are not at the same frequency.

This is because the degree of penetration of the magnetic flux induced by the excitation coil and causing eddy current loss inside the metal material to be inspected is inversely proportional to the resistivity of the metal material.

In other words, for materials A, B, and C with low resistivity, when the distance between the coin surface and the detection coil is short, an eddy current is generated on the coin surface, resulting in a very large phase difference, but conversely, when this distance increases, the phase difference increases. As a result of the sudden decrease in
There is a big difference between B and C.

Therefore, as mentioned above, even if the frequency is set based on one experimental result, the distance between the coin surface and the detection coil is not uniform depending on the coin insertion situation, so the value will not be constant and it will be meaningless. Recognize.

As a countermeasure for this, either set the width of the coin passage approximately equal to the thickness of the coin so that the distance between the coin surface and the detection coil is always constant, or tilt the coin passage so that the coins roll along the wall of the coin passage. There is a way to make it constant.

However, even if the distance between the coin and the detection coil is made constant in this way, various counterfeit coins may be generated.

For example, it is possible to use a material whose specific resistance is relatively similar to that of a genuine coin, make the outer diameter the same, change the plate thickness appropriately, and make the overall electrical characteristics equivalent to that of a genuine coin, or make a hole in a part with approximately the same shape. Conceivable.

As a countermeasure against these counterfeit coins, a method is known in which at least two frequencies are measured and a logic circuit is used to determine the measurement results at the three frequencies in order to more clearly distinguish the magnetic properties that differ depending on the material and shape of the coin.

Although this method allows for relatively accurate discrimination, it is a very expensive device because it applies different frequencies to at least two or more excitation coils and performs circuit processing at different frequencies. It is something.

From this point of view, the present invention proposes a method for clearly grasping magnetic characteristics using one type of frequency without using two types of shaving numbers.

From Figures 1 and 2, it is clear that the intersection frequencies of magnetic characteristics A, B, C, and D differ depending on the difference in the distance between the coin surface and the detection coil. For example, magnetic characteristics B and C differ from the coin surface. When the interval between the detection coils is set to 07IL7IL, the zero crossing frequency is 3.8KC, but when it is set to 2, it is 5KC.

Therefore, even if the frequency of the excitation coil is set to only 3.8KC, the distance between the coin surface and the detection coil will be 07ILr.
By inspecting both IL and two angles, it is possible to sufficiently confirm the difference in magnetic properties even at one type of frequency.

Utilizing such characteristics, the present invention provides a coin sorting device that uses only one type of frequency, has a simple configuration, can confirm differences in magnetic characteristics, and performs highly accurate sorting.

One embodiment will be described in detail below based on the drawings.

FIG. 3 is a schematic diagram of the device of the present invention, in which a test coin C inserted from the coin input port 4 is sequentially measured for phase difference by detectors 5 and 6 while rolling in the coin passage 3. The corresponding level setters L1.6 shown in FIG. At L2, the denomination of the test coin C is determined.

The husband's detectors 5 and 6 are composed of an excitation coil 1 and a detection coil 2 wound around cores 1' and 2', and both coils may be arranged on the same surface as the coin surface as shown in Fig. 4. Alternatively, as shown in FIG. 5, the coins may be placed on one side and the other side with the coin sandwiched between them, depending on the design of the device.

Further, the phase detection devices 15 and 16 of the detectors 5 and 6 detect the signal phase difference between the excitation coil 1 and the detection coil 2, respectively, and output a voltage level corresponding to the detected value.

The frequencies applied to the excitation coils 1 of the detectors 5 and 6 are the same, but the distance between the detection surface of the detection coil 2 and the coin surface is different between the coin passage wall 7 and the detection coil 2. The distance t between the core 2 and the core 2 must be different.

When the test coin C passes through such detectors 5 and 6, a phase difference corresponding to this interval t is detected, and the level setter L1. The denomination is determined at L2.

That is, the level setter L1 is set at a level within an allowable error range for the phase difference that the detector 5 can take with a genuine coin depending on the denomination handled by the coin sorting device, and the level setter L1 is set at a level within an allowable error range.
In the case of No. 2, the detector 6 is also set at a level within an allowable error range for the phase difference that can be obtained with the genuine coin depending on the denomination.

and both level setters L1. If the above judgments of L2 match, that is, using AND logic, this coin sorting device finally judges the denomination of the test coin C, and determines whether the coin storage cylinders 8, 9, and 10 provided for each denomination have fallen. Introduce test coin C.

For example, in this embodiment whose purpose is to distinguish between cupronickel-copper clad coins, silver coins, and cupronickel coins, the value of t of the detector 5 is set to 0.
1171 (i.e. the characteristic shown in FIG. 1) The value of t of the detector 6 is 21+! 2+1 (i.e., the characteristics shown in Figure 2), and both excitation coils 1 are connected to the oscillator 20 to generate 3.8KC.
This induces an alternating magnetic field.

Regarding the characteristics shown in FIG. 1, the level setter L1 is set with an upper limit voltage level 11 and a lower limit voltage level e2 corresponding to a phase difference of 104 degrees, and a phase difference of 36 degrees.
Upper limit voltage level 12 and lower limit voltage level e4 correspond to
is set.

Therefore, when the signal voltage output from the phase detection device 15 is within the range of 41 to e2, the level setter L1 determines that a clad coin or a silver coin whose phase difference is around 104' has passed through the detector 5. If the signal voltage output from the phase detection device 15 is within the range of 13 to 14, it is determined that the cupronickel coin has passed through the detector 5 with a phase difference of around 36°. to produce an output N.

On the other hand, regarding the characteristics shown in FIG. 2, an upper limit voltage level 15 and a lower limit type mole level 16 are set in the level setter L2 corresponding to a phase difference of 36 degrees, and an upper limit voltage level is set corresponding to a phase difference of 26 degrees. 17 and a lower limit voltage level 18 are set, and an upper limit voltage level l is set corresponding to a phase difference of 13°.
, and a lower limit voltage level 11o are set.

Therefore, when the coin passes through the detector 6, the level setter L2
, the signal voltage output from the phase detection device 16 is 12~
If it is within the range of 16, it will be determined that it is a silver coin and output O will be generated.
If it is within the range of ~18, it is determined that it is a clad coin and an output P is generated, and if it is within the range of l, ~110, it is determined that it is a cupronickel coin and an output Q is generated.

Therefore, when a coin C is inserted and the outputs M and O are generated in the level setters L1 and L2, the output of the AND gate 17 indicates that it is a silver coin, and the level setters L1 and L2 respectively output an output M and an output O. L
When output N and output Q occur at 2, respectively, the AND gate 18
The output of L1. indicates that it is a cupronickel coin, and the level setter L1. When husband output M and output P occur in L2, AND
The output of gate 19 indicates that the coin is a clad coin.

However, the phase difference detected by the detectors 5 and 6 of the test coin C is the level setter L1. If one or both of L2 does not fall within the allowable level, no output is obtained from the AND gates 17, 18, and 19°, and the coin is determined to be a counterfeit coin and is returned from the return path 11.

The introduction means for each of the coin storage cylinders 8, 9 and 10 is to use any one of the coin storage cylinder lids 12, 13 and 14 which are located at the upper end opening of the iron cylinder and form the coin passage 3 when closed.
The ND gates 17, 18, and 19 may be opened by a solenoid based on their outputs, and after confirmation of coin introduction by a well-known coin switch, the gates may be closed again.
If there is no output from the AND logic, none of the coin storage cylinder lids 12, 13, 14 is opened and the coins are introduced into the return path 11.

The present invention, which has been described in detail above, makes it possible to clearly grasp the magnetic characteristics of test coins by measuring the distance between the coin surface and the detection coil while changing the distance between the coin surface and the detection coil, and is expected to perform highly accurate sorting.

Moreover, since only a single frequency is used, the circuit is not complicated and can be manufactured at low cost.

[Brief explanation of drawings]

Figures 1 and 2 show the difference between the coin surface and the detection coil, respectively.
Fig. 3 shows the coin sorting device of the present invention, and Figs. 4 and 5 show the outline of the detector, respectively. FIG. 6 is a block diagram showing the circuit. Explanation of main drawing numbers, 1...excitation coil, 2...
...Detection coil, 3...Coin passage.

Claims (1)

[Claims] 1. At least two detectors that are connected to the excitation coil and the detection coil are sequentially arranged along the direction of movement of the coin so that the distances from each detection coil to the coin surface are different from each other, and
An oscillating magnetic field having the same frequency is formed in all of the excitation coils, and when a coin passes, the value of the signal phase difference between the excitation coil and the detection coil measured by each of the detectors is within a predetermined range. A coin sorting device that determines passing coins as appropriate.