JP2000182113A - Device for discriminating coin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To discriminate a coin based on recessed and projected patterns formed on the front and back surfaces of a coin while using a coil sensor capable of resisting to stain and a disturbance light. SOLUTION: Coil sensors 1 and 2 using a pot core arranged to face each side surface part of a coin carrier path 3 are arranged and the coin is discriminated by permitting a high frequency current to flow in the coil sensors and comparing the pattern of amplitude change when the coin 4 passes in front of the coil sensors with a reference pattern in a coin identifying device. In the device, the core gap width and core center diameter of the pot cores 1 and 2 are made to be smaller than the diameter of the recessed and projected patterns formed on the front and back surfaces of the coin 4 to be a detection object.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coin discriminating apparatus for discriminating coins based on patterns formed on the front and back surfaces of the coins.

[0002]

2. Description of the Related Art In recent years, crimes involving altered coins made to resemble 500-yen coins by using drills or the like on foreign coins made of a copper-based material for vending machines have been rapidly increasing. With current sensors, the thickness and material of coins are averaged to identify them, so that such altered coins cannot be completely excluded. Under such circumstances, there is a demand for the development of a coin discriminating apparatus having higher discrimination accuracy, such as accurately discriminating between a genuine coin and a falsified coin based on a pattern formed on the front and back surfaces of the coin. For that purpose, it is necessary to determine the irregularities (pictures, drill marks, cutting marks, etc.) formed on the front and back surfaces of the coin.

[0003] Among the conventional coin discriminating apparatuses, those which can detect irregularities formed on the front and back surfaces of coins are disclosed in Japanese Patent Application Laid-Open No. H2-259982 (G07D 5/02). There is. The coin identification device identifies the authenticity of a coin by collating data extracted by optically reading the irregularities on the front and back surfaces of the coin with an optical sensor against data of a genuine coin registered in advance. It is.

[0004]

However, in the above-mentioned optical coin discriminating apparatus, if the light emitting portion or the light receiving portion of the optical sensor becomes dirty with the elapse of the use period, the level of the detection data changes, and Even if light leaks in from the outside,
There is a problem that the detection data is susceptible to dirt and disturbance light such as disturbance of the detection data.

[0005] On the other hand, a magnetic coin discriminating apparatus using a coil sensor is not affected by dirt or disturbance light. Nothing was able to detect the irregularities formed on the front and back surfaces.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and to make it possible to identify coins based on an uneven pattern formed on the front and back surfaces of the coins while using a coil sensor resistant to dirt and disturbance light. It is intended for.

[0007]

According to a first aspect of the present invention, there is provided a coin discriminating apparatus comprising: a coil sensor using a pot core disposed to face a side surface of a coin transport path; And a signal processing circuit for discriminating the coin by comparing a pattern of amplitude change when the coin passes in front of the coil sensor with a reference pattern, wherein the pot core Are characterized in that the core gap width and the core center diameter are smaller than the diameters of the irregularities formed on the front and back surfaces of the coin to be detected. By doing so, coins can be identified based on the concavo-convex pattern formed on the front and back surfaces of the coin while using a coil sensor that is resistant to dirt and disturbance light.

[0008] A coin discriminating apparatus according to a second aspect is characterized in that a plurality of pairs of the coil sensors are provided in a vertical line in accordance with the diameter of a coin to be detected. By doing so, the detection area is increased and the detection accuracy is further improved.

Further, the coin identification device according to claim 3 is
It is characterized in that output signals of coil sensors adjacent to the coil sensors provided in one column are differentially amplified to be detection signals. This makes it possible to detect the concavo-convex of the neighbors, reduce the number of components of the signal processing circuit, and reduce the cost.

[0010]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is an arrangement diagram of a core sensor with respect to a coin transport path. In FIG. 1, reference numerals 1 and 2 denote pot core sensors, 3 denotes a coin transport path, and 4 denotes a coin.

The pot core sensors 1 and 2 are disposed on both sides of the coin transport path 3 at positions facing the front and back of the coin 4 transported therein. The pot core sensors 1 and 2 are configured by incorporating a coil (not shown) in a core gap 6 around a core center 5 of the pot core as shown in FIG. A high-frequency current is passed through the pot core sensors 1 and 2, and the coins are identified by comparing a pattern of amplitude change when the coin 4 passes between the pot core sensors 1 and 2 with a reference pattern.

FIG. 3 is a circuit diagram of the signal processing circuit. Reference numerals 1 and 2 correspond to those in FIG. 1, 11 is a coil oscillation / reception unit, 12 is a DC cut unit, 13 is an AC amplification unit, 14 is a half-wave rectification and peak hold unit, and 15 is a DC smoothing unit. And an impedance conversion unit. In the coil oscillation / reception unit 11, high frequency (for example, 280 kHz) is applied to the pot core sensors 1 and 2 while being controlled to start and stop the oscillation by the microcomputer 10 through the terminal C.
Of current. And the coin 4 is the pot core sensor 1,
The change in amplitude when the signal passes between the two is supplied to a half-wave rectifier and peak hold unit 14 via a DC cut unit 12 and an AC amplifier unit 13 each composed of a capacitor.

FIG. 4A shows a waveform at point X when the coin 4 is not present, and FIG. 4B shows a waveform at point X when the coin 4 passes between the pot core sensors 1 and 2. Is shown. In the half-wave rectification and peak hold unit 14, the input high-frequency signal is half-wave rectified by the diode D1, and peak-held by the capacitor C4. As a result, the waveform at the point X is shown in FIG.
Then, the waveform at the point Y is as shown in FIG.

The signal is smoothed by a DC smoothing and impedance conversion unit 15 and impedance conversion is performed according to the low impedance of the A / D input of the microcomputer 10. In response, the microcomputer 10 compares the pattern of the input signal with the reference pattern stored therein, and determines that the coin is a genuine coin if the two patterns match.

In such a coin discriminating apparatus, the relationship between the size of the pot core sensors 1 and 2 and the size of the pattern on the front and back of the coin will be examined.

As a test sample, a test gauge in which a circular concave portion was formed in the center of the front and back of a stainless steel disk as shown in FIG. 5 was used instead of a coin. The gauge prepares four disks of diameter 26.5mm and thickness 1.85mm, 0.3mm in depth at the center of the front and back of those disks.
And the diameters are 4.0mm, 3.0mm, 2.0mm,
A circular recess of 1.0 mm was formed. On the other hand, as the pot core sensors 1 and 2, small-diameter cores having the size shown in FIG. 6 were used. A to F in FIG. 6 indicate the size of each part shown in FIG. 2 in mm.

When the gauge was inserted into the coin discriminating apparatus, output waveforms as shown in FIGS. 8A to 8D were obtained at the A / D input terminals of the microcomputer 10 in FIG. . 8A shows a gauge provided with a recess having a diameter of 4.0 mm, FIG. 8B shows a gauge provided with a recess having a diameter of 3.0 mm, and FIG. The provided gauge, FIG. 8 (d), shows a state in which a gauge provided with a concave portion having a diameter of 1.0 mm is supplied.

As is apparent from FIG. 8, the waveform of the chevron at the center changes according to the size of the concave portion of the gauge. That is, in the concave portion having a core center diameter of 2.0 mm of the pot core and 4.0 mm larger than the core gap width of 1.0 mm, a peak corresponding to the concave portion clearly appears, but the concave portion is 3.0 mm.
Below the peak, no peak can be detected, and in the case of FIG. 8C in which the core center diameter C and the recess diameter match, the peak has been reduced in reverse. In FIG. 8D, the diameter of the concave portion is further reduced to the same size as the width of the core gap F, and the concave portion can hardly be detected.

Further, as the pot core sensors 1 and 2,
A similar experiment was performed using a core having a size larger than the small-diameter core and having a size shown as a comparative core in FIG. FIG. 7 shows the height ΔV of the central waveform in each case. As can be seen from these figures, the smaller the core diameter A, the core center diameter D, and the core gap F, the larger ΔV can be obtained, which is advantageous for the unevenness resolution of the front and back surfaces of the coin. This is the same for the convex. This is the core diameter A
, The core center diameter D and the core gap F
This is because the magnetic resistance decreases as much as. Next, it will be described by an equation.

FIG. 9 is an explanatory diagram of a magnetic circuit of the pot core, and dotted lines indicate lines of magnetic force. The magnetomotive force of the magnetic circuit is N
Assuming that I [AT], the magnetic flux is φ [Wb], the magnetic resistance is Rm, the magnetic permeability of the core is μ [H / m], the core magnetic path length is L, and the core sectional area is Sc, a gap is formed in the magnetic circuit. If not,

## EQU1 ## φ = NI / Rm [Wb]

## EQU2 ## Rm = L / μSc

On the other hand, if there is a gap in the magnetic circuit such as a pot core, the width of the gap is G, the permeability of the gap is μ ₀ , and the cross-sectional area of the gap is Sg. , The magnetic flux density B in the gap
g and the magnetic field Hg in the gap are

Rm = L / μSc + G / μ ₀ Sg

## EQU4 ## Bg = φ / Sg

Hg = Bg / μ ₀

Then, Equation 3 is substituted for Rm in Equation 1, and
Substituting the φ into Equation 4 and further substituting the Bg into Equation 5, eventually yields:

Hg = NI / [(μ ₀ / μ) (Sg / Sc) L + G]

From the equation (6), to increase the magnetic field Hg in the gap, the magnetomotive force NI, the core permeability μ and the core cross-sectional area Sc must be increased, and the gap width G and the gap cross-sectional area Sg must be reduced. It is understood that it is necessary to shorten the magnetic path length L of the core.

Usually, μ >> μ ₀ , and the magnetic resistance of the core portion can be almost neglected.

Hg = NI / G

On the other hand, according to Ampere's law, the magnetic field Hr on the circumference r away from the gap is

[Mathematical formula-see original document] An equal magnetic field of Hr = Hg / πr is obtained.

Therefore, the stronger the magnetic field Hg in the gap, the stronger the magnetic field Hr on the circumference distant from the gap, and consequently, the smaller the core center diameter and the core gap, the better the unevenness resolution of the coin front and back. You can see that.

As described above, according to the present invention, the core center diameter and the core gap width of the pot core sensors 1 and 2 are defined as: core center diameter <diameter of irregularities to be detected; The relationship of gap width ≦ diameter of unevenness to be detected is set. In particular, the core center diameter
It is desirable that the diameter be not more than の of the diameter of the unevenness to be detected.

Using the small diameter core pot core sensors 1 and 2 shown in FIG. 6, a plurality of drill holes were drilled on the surface of a 500-yen coin and a modified coin which is often used in place of the 500-yen coin. When the output waveform was examined using a 500 won coin, a waveform as shown in FIG. 10 was obtained. FIG. 10A shows a 500-yen coin, and FIG. 10B shows a modified 500-won coin.

As apparent from FIG. 10, the 500-yen coin shows a relatively gradual change, while the modified 500-won coin has a waveform fluctuating corresponding to the drilled hole. It clearly appears, and both can be clearly distinguished.

The connection of the pot core sensors 1 and 2 is achieved by connecting a pair of pot core sensors 1 and 2 disposed on both sides of the coin transport path 3 with opposite polarities that the magnetic fields in the coin transport path 3 cancel each other out and weaken. Connect to phase. If you connect like that,
Since the magnetic flux flows only through the surface without deeply penetrating into the coin, the unevenness of the surface tends to appear in the output, and even if the coin may rattle left and right in the coin transport path, the output due to rattling Variation can be reduced.

When the size of the pot core sensors 1 and 2 is reduced, the detection area for coins is reduced.
A pair of pot core sensors 1 and 2 disposed on opposite sides of the coin transport path 3 are vertically aligned as shown in FIG. 11A in accordance with the diameter of a 500-yen coin, the largest coin in Japan. If it arrange | positions, a detection area will expand and detection accuracy will improve more. At this time, if the output signals of adjacent ones of the pot core sensors provided in a vertical line are differentially amplified and used as a detection signal, unevenness of the adjacent ones can be detected, and the number of parts of the signal processing circuit can be reduced. And cost can be reduced.

When the cores are arranged vertically in a row, as shown in FIG.
Is an oscillating elliptical pot core large enough to cover the other vertical row of pot cores, oscillate at a low frequency of about 100 kHz, increase the skin depth of the eddy current, transmit the magnetic flux, and Irregularities may be detected collectively.

In order to detect the irregularities on the front and back surfaces of the coin, it is more advantageous to increase the oscillation frequency of the pot core sensors 1 and 2, set the eddy current penetration of the coin to be shallow, and make the coin more sensitive to the surface portion of the coin. There is a suitable oscillation frequency of about 300 kHz.

[0034]

Since the present invention is configured as described above, it has the following effects. That is, in the coin discriminating apparatus according to the first aspect, the core gap width and the core center diameter of the pot core are smaller than the diameters of the irregularities formed on the front and back surfaces of the coin to be detected.
While using a coil sensor that is resistant to dirt and disturbance light, coin identification based on the concavo-convex pattern formed on the front and back surfaces of the coin becomes possible.

In the coin discriminating device according to the second aspect, since a plurality of pairs of coil sensors are provided in a vertical line in accordance with the diameter of the coin to be detected, the detection area is widened and the detection accuracy is further improved.

Further, the coin identification device according to claim 3 is
Differential amplification of the output signal of the coil sensor adjacent to the coil sensor arranged in a vertical line enables detection of unevenness between adjacent sensors, reducing the number of parts of the signal processing circuit and reducing cost. Will be possible.

[Brief description of the drawings]

FIG. 1 is a layout diagram of a core sensor with respect to a coin transport path.

FIG. 2 is a view showing a pot core.

FIG. 3 is a circuit diagram of a signal processing circuit.

FIG. 4 is a waveform diagram of each part of the circuit.

FIG. 5 is a diagram showing a test gauge.

FIG. 6 is a diagram showing the size of a test core.

FIG. 7 is a diagram showing test results.

FIG. 8 is a test waveform diagram.

FIG. 9 is an explanatory diagram of a magnetic circuit of the pot core.

FIG. 10 is a waveform diagram of a true coin and a false coin.

FIG. 11 is another arrangement example of the core sensor.

[Explanation of symbols]

 1, 2, pot core sensor 3, coin transport path 4, coin 10, microcomputer 11, coil oscillation / reception section 12, DC cut section 13, AC amplifier section 14, half-wave rectification and peak hold section 15, DC smoothing and Impedance converter

Claims (3)

[Claims] 1. A coil sensor using a pot core disposed opposite to a side surface of a coin conveying path, and a high-frequency current is applied to the coil sensor, and a pattern of an amplitude change when a coin passes in front of the coil sensor is described. A coin discriminating device comprising a signal processing circuit for discriminating coins by comparing with a reference pattern, wherein a core gap width and a core center diameter of the pot core are formed on the front and back surfaces of coins to be detected. A coin discriminating device characterized by having a diameter smaller than the diameter of the irregularities. 2. A coin discriminating apparatus according to claim 1, wherein a plurality of pairs of said coil sensors are provided in a vertical line in accordance with the diameter of a coin to be detected. 3. The coin discriminating apparatus according to claim 2, wherein the output signals of the coil sensors adjacent to the coil sensors provided in a vertical line are differentially amplified to obtain a detection signal.