JP3028380B2 - Magnetic quality detection method and magnetic quality detection device using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[Object of the invention]

[0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic material detecting method and a magnetic material detecting device using the same, and more particularly to the detection of magnetic material of a magnetic material contained in printing ink such as banknotes.

[0003]

2. Description of the Related Art In recent years, the progress of copying technology has been remarkable, and a problem has arisen that securities such as banknotes and checks are misused by copying.

[0004] Therefore, research for identifying such paper sheets is being rapidly promoted.

For example, two types of bills are distinguished by light and magnetism.

[0006] Among them, the magnetic discrimination utilizes the fact that magnetic ink is used for a banknote in some form, and detects the distribution of the magnetic ink to identify the banknote.

For example, conventionally, a magnetic field is applied to a banknote in advance using a magnet, and an intrinsic magnetic material, a magnetic pencil, a magnetic copy, or the like is used depending on the residual magnetic flux density after removing the magnetic field. There is a method of determining whether or not. (JP-A-52-152793)

[0008]

However, in the above-described method, since only the residual magnetic flux density is observed, the residual magnetic flux density becomes almost the same as that of the magnetic ink when it is lightly painted with a magnetic pencil or the like. There was a problem that identification was not possible.

In general, a measuring device for a magnetic material can measure a residual magnetic flux density, a coercive force, etc., but the object to be measured must be kept stationary, and the measurement takes a certain amount of time. However, when it is desired to determine only whether or not the magnetic material has a specific magnetic property, the operation is complicated, and it is impossible to measure without a certain amount of mass. There was a problem that measurement was not possible.

The present invention has been made in view of the above circumstances, and has as its object to provide a method for easily detecting the magnetic quality of a magnetic material with a simple device.

[Structure of the Invention]

[0012]

Therefore, in the method of the present invention, a bias magnetic field set according to the magnetic properties of the magnetic substance to be detected is applied to the magnetic sensor, and the target magnetic substance passes therethrough. At times, the output from the magnetic sensor is prevented from being output to detect whether or not the magnetic body has a desired magnetic quality.

[0013] A magnetic material detecting apparatus according to the present invention is provided with a magnetic sensor for measuring a change in magnetic flux distribution, and an absolute value of a magnetic substance to be detected, which is disposed on the upstream side of the magnetic sensor and whose coercive force is smaller than its coercive force. A first magnet for applying a large saturation magnetic field;
A second magnet disposed in the vicinity of the magnetic sensor and configured to apply a magnetic field having a polarity opposite to that of the first magnet and having a value equal to the coercive force of the magnetic substance to be detected; When the magnetic material passes, the output from the magnetic sensor is prevented from being output, thereby detecting whether or not the magnetic material has a desired magnetic quality.

[0014]

The coercive force Hc of the magnetic material is, as shown in FIG. 8 (a), the point of intersection between the H axis and the loop in the magnetic flux density-magnetic field strength (BH) curve. Take. At this time, that is, when the magnetic field strength H is Hc or -Hc,
The magnetic flux density passing through the inside of the magnetic body is zero. When a magnetic material having a residual magnetic flux density of -Br enters a magnetic field of + Hc, the absolute value of the residual magnetic flux density of the magnetic material decreases to zero.

Even if the device in the state of Br = 0 moves on the differential type magnetoresistive element as shown in FIG. 8 (b), no change occurs in the magnetic field and no change occurs in the differential output.

Conversely, when the magnetic material of + Br enters the magnetic field of + Hc, the magnetic flux distribution is changed due to the residual magnetic flux density of Br ', and a change appears in the differential output.

The same applies to the case of a magnetic flux distribution of -Hc.

The present invention has been made in view of this point, and utilizes the fact that when the magnetic field strength H is Hc or -Hc, the magnetic flux density of the coercive force Hc passing through the inside of the magnetic material becomes zero. When the magnetic material passes, whether or not the magnetic material has a coercive force Hc is detected based on whether or not the magnetic flux density becomes zero, that is, whether or not the magnetic flux distribution changes.

According to the above configuration, it is possible to detect while scanning, and it is possible to easily and immediately determine whether or not the magnetic material has a specific magnetic property.

It should be noted that the magnetic body may be moved or the detection device may be moved. In short, the magnetic material may be moved relatively to the measuring device.

For example, when it is desired to detect the magnetic quality of a bill,
When the magnetic field strength at the detection position of the magnetic material is set to the magnitude of the coercive force of the magnetic ink of the banknote, the magnetic material having a coercive force other than the magnetic ink of the banknote passes through the magnetoresistive element because the residual magnetic flux density is not zero. A change is detected in the distribution of the magnetic flux, which is detected.

Although a non-magnetized piece is judged to be a genuine bill, a pattern can be judged by using it together with a conventional magnetic pattern sensing.

[0023]

Embodiments of the present invention will be described below in detail with reference to the drawings.

Embodiment 1 FIGS. 1 (a) and 1 (b) are a schematic explanatory view and a cross-sectional view of a main part of a bill validator according to an embodiment of the present invention.

This discriminating apparatus is sequentially arranged at predetermined intervals in the traveling direction a of the banknote 1, and generates a negative magnetic field -Hm at a position where a magnetic material to be detected passes.
, A second magnet 20 that emits a positive magnetic field Hc which is a magnetic field of the reverse polarity of the first magnet, and a second magnet 20 that is disposed near the second magnet 20. A differential type magnetoresistive element 30 as a magnetic sensor biased to a positive magnetic field Hc, and a judging means for judging whether it is a genuine note or a magnetic copy based on the output of the differential type magnetoresistive element 30 40. As shown in FIG. 1 (b), the bill 1 is configured to travel on a top glass G of the main body of the detection device by a transfer means (not shown). The first and second magnets are disposed on the back surface of a support substrate 50 installed below and parallel to the top glass G, and the differential type magnetoresistive element 30 is provided.
Are provided on the surface of the support substrate 50. The differential type magnetoresistive element 30 is constituted by a thin film magnetoresistive element 32 disposed on the surface of an insulating substrate 31. Here, the positive magnetic field Hc by the second magnet 20 is set to the coercive force of the magnetic ink of the bill. The absolute value of the negative magnetic field −Hm is
It is assumed to be sufficiently larger than the absolute value of the positive magnetic field Hc.

Next, a method of recognizing bills using the bill recognizing device will be described.

The banknote 1 is caused to travel in the direction of arrow a, and as shown in FIG. 2, first, the magnetic material to be measured is negatively saturated with the first magnet, and then the magnetoresistance biased by the second magnet is performed. The element determines whether it is a genuine note or a magnetic copy.

Here, the differential magnetic resistance element 30 detects a magnetic field change when a magnetic material having a negative residual magnetic flux density -Br is passed through a magnetic field of + Hc by an applied magnetic field of -Hm. . After a genuine bill having a magnetic pattern composed of magnetic ink having a coercive force of + Hc is negatively saturated by the applied magnetic field, it passes through the magnetic field of -Hm and remains in the state of the residual magnetic flux density -Br in the applied magnetic field of + Hc. , The residual magnetic flux density becomes 0 in this + Hc magnetic field, and the distribution of the applied magnetic field does not change, so that no change appears in the differential type magnetoresistive element. In the case of a magnetic material having a coercive force different from Hc, the residual magnetic flux density does not become 0 in the magnetic field of + Hc, a change occurs in the distribution of the applied magnetic field, and a change appears in the differential magnetoresistive element.

Therefore, if no change is detected in the differential type magnetoresistive element, it is determined that it is a genuine note, and the operation proceeds to the next operation. If a change is detected in the differential type magnetoresistive element, it is not a genuine note. Judgment is made and the transport direction of the bill is reversed to return to the bill insertion slot.

Thus, according to the bill validator of the present invention, bills can be distinguished very easily in a short time.

Embodiment 2 Next, a bill discriminating apparatus according to a second embodiment of the present invention will be described.

This discriminating device is characterized in that a magnetic pattern detecting device is added to the magnetic discriminating device shown in the first embodiment. This device is shown in FIG.
As shown in FIG. 4, three differential magnetic resistances as magnetic sensors for detecting magnetic properties are sequentially arranged at predetermined intervals on the surface of the support substrate 500 along the width direction b of the banknote 1. The element 300, a magnetic pattern detecting magnetoresistive element array 600 disposed upstream of the differential type magnetoresistive elements 300 with respect to the traveling direction a of the banknote 1, and a back side of the magnetoresistive element array 600. A first magnet 100 that emits a negative magnetic field -Hm at a position where the magnetic substance to be detected passes, and a reverse polarity of the first magnet that is disposed on the back side of the magnetoresistive element 300. And a second magnet 200 which emits a positive magnetic field Hc which is a magnetic field of the differential type and the magnetoresistive element array 600.
And determination means 400 for determining whether the copy is a genuine note or a magnetic copy based on the output.

The banknote 1 is caused to travel in the direction of arrow a, and a change in the magnetic field distribution when the banknote 1 passes through the region of the applied magnetic field of -Hm by the first magnet 100 is detected by a differential type magnetoresistive element array. , Detect the magnetic pattern. The denomination and authenticity of the magnetic pattern can be determined by a known method.

On the other hand, the banknote 1 passes through the region of the applied magnetic field of -Hm by the first magnet 100, and after being negatively saturated, exits the magnetic field of -Hm and remains in the state of the residual magnetic flux density -Br.
, The magnetic resistance element 300 biased by the second magnet detects whether or not there is a change in the magnetic field distribution, thereby determining whether or not the ink is intrinsic magnetic ink.

Here, as in the first embodiment, -Hm
The magnetic field change when the magnetic material once saturated by the applied magnetic field and having a residual magnetic flux density of -Br passes through the magnetic field of + Hc is detected by the differential magnetoresistive element 30. When a genuine bill having a magnetic pattern composed of magnetic ink having a coercive force of + Hc is negatively saturated by an applied magnetic field of -Hm, passes through the magnetic field of -Hm, and passes with a residual magnetic flux density of -Br. , -Hc, this + Hc
Since the residual magnetic flux density becomes 0 in the magnetic field of No. 1 and the distribution of the applied magnetic field does not change, no change appears in the differential type magnetoresistive element. In the case of a magnetic material having a coercive force different from Hc of the magnetic ink, the residual magnetic flux density does not become 0 in this + Hc magnetic field, and the distribution of the applied magnetic field changes.
A change appears in the differential type magnetoresistive element. The determination unit determines both the magnetic pattern and the magnetic quality to determine whether the denomination is true or false.

Thus, according to the bill validator of the present invention, bills can be recognized very easily in a short time.

Forms that do not have magnetism can not be detected by detection using only the magnetic material detection sensor, and cannot be detected. However, this device also has a magnetic pattern detection device. Is gone. Further, the first magnet is used as a magnetic field for magnetic pattern detection, and is used as a magnetic field for negative saturation in the magnetic quality detection sensor, and can be detected without increasing the size of the device. .

In the above embodiment, permanent magnets were used for both the first and second magnets as the bias magnets. However, as shown in FIG.
When the magnetic body to be detected is changed, the strength of the bias magnetic field may be adjusted by changing the coil current.

Further, as shown in FIG.
And the yoke 20 magnetized by the first magnet 100
2, and the yoke 202 may be replaced as necessary.

Further, as shown in FIG.
A permanent magnet is used as the magnet, but the bias magnetic field may be changed by attaching a position adjusting means 204 to the second magnet 203 and adjusting the height. Further, even when the first magnetic field is applied in a direction opposite to that of the embodiment such as + Hm and the second magnetic field is applied in a direction opposite to that of -Hc, the detection can be performed in exactly the same manner.

[0041]

As described above, according to the present invention, a bias magnetic field set according to the magnetic properties of the magnetic material to be detected is applied to the magnetic sensor, and the desired magnetic material is applied. When passing through, the output from the magnetic sensor is not output to detect the desired magnetic quality, so it is easy and immediate to determine whether or not it has a specific magnetic quality. Becomes

[Brief description of the drawings]

FIG. 1 is a diagram showing a bill validator according to an embodiment of the present invention.

FIG. 2 is a diagram showing a hysteresis curve of a bill to be identified by the apparatus according to the embodiment of the present invention.

FIG. 3 is a view showing a bill validator according to a second embodiment of the present invention.

FIG. 4 is a view showing a bill validator according to a second embodiment of the present invention.

FIG. 5 is a view showing a modification of the magnetic sensor of the bill discriminating apparatus of the present invention.

FIG. 6 is a diagram showing a modification of the magnetic sensor of the bill validator of the present invention.

FIG. 7 is a diagram showing a modification of the magnetic sensor of the bill validator of the present invention.

FIG. 8 is a diagram illustrating the principle of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 1st magnet 20 2nd magnet 30 Differential type magnetoresistive element 40 Judgment means 100 1st magnet 200 2nd magnet 300 Differential type magnetoresistive element 400 Judgment means 500 Support substrate 600 Magnetoresistive element array

Claims (4)

(57) [Claims] A first magnetic field required to saturate a magnetic substance to be detected is set according to a saturation magnetic field applying step of applying the first magnetic field to a detection target, and the magnetic property of the magnetic substance to be detected; A second magnetic field having a polarity opposite to that of the first magnetic field is applied as a bias magnetic field to the magnetic sensor, and is passed through the object to which the first magnetic field is applied; A detection step of detecting a change, and detecting whether the object to be detected is a magnetic substance having a desired magnetic quality. 2. A magnetic sensor for measuring a change in magnetic flux distribution, and a saturation magnetic field having an absolute value larger than its coercive force is applied to a magnetic body disposed upstream of the magnetic sensor and to be detected. A first magnet disposed in the vicinity of the magnetic sensor and having a polarity opposite to that of the first magnet and applying a magnetic field having a value equal to a coercive force of a magnetic body to be detected; And the output from the magnetic sensor
A magnetic material detecting device for detecting whether a magnetic material has a desired magnetic quality. 3. The magnetic substance detecting device according to claim 2, wherein the second magnet is detachably configured. 4. A magnetic sensor for measuring a change in magnetic flux distribution, and a saturation magnetic field having an absolute value larger than its coercive force is applied to a magnetic body disposed upstream of the magnetic sensor and to be detected. A first magnet, a magnetic pattern detecting means disposed near the first magnet and detecting a magnetic pattern, and a magnetic pattern detecting means disposed near the magnetic sensor and having a polarity opposite to that of the first magnet and detected. A second magnet for applying a magnetic field having a value equal to the coercive force of the magnetic material to be obtained.