JP2911066B2 - Multi-pulse magnetic marker - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-pulse type magnetic marker attached to an article for detecting its presence, and more particularly, as a marker for managing the distribution of articles or as a security tag for preventing theft in stores. The present invention relates to a multi-pulse magnetic marker used.

[0002]

2. Description of the Related Art It is common practice to attach a marker to an article and use the marker to detect the quantity of the article or to prevent theft of the article.

Conventionally, magnets and microwaves have been applied to this type of marker, for example, a marker that applies a magnetic field to an amorphous thin body or a thin wire, or a marker that irradiates an aluminum foil with a microwave. In particular, in the case of using an amorphous magnetic material as a marker, when a target product to be detected having the marker attached is placed in an AC magnetic field, the magnetization of the amorphous magnetic material is reversed by the AC magnetic field, and a high-frequency signal is emitted into space. The presence of the article can be recognized by detecting the high frequency radiated into the space.

[0004] Amorphous magnetic materials have superior magnetic properties as compared to conventional materials. Therefore, by utilizing this magnetic characteristic of the amorphous magnetic material, a highly sensitive and small magnetic marker can be realized.

[0005]

As described above, a highly sensitive and small magnetic marker can be realized by using an amorphous magnetic material. However, a marker using an amorphous magnetic material is still as follows. Had a serious problem.

That is, this type of marker generally outputs a single pulse in an AC magnetic field, and can only detect an article based on the presence or absence of the pulse, and cannot confirm the type of the article. It was possible.

In order to solve such a problem, there has been proposed a marker using a plurality of soft magnetic materials having different coercive forces in order to identify an article (for example, Japanese Patent Application Laid-Open No. Hei 2-2).
03295).

Although the use of such a marker makes it possible to identify an article, it has a problem in production and a problem in use. That is, in order to obtain a plurality of independent pulses from a plurality of soft magnetic materials, it is necessary to prepare the soft magnetic materials having sufficiently different coercive forces. In order to detect a sufficiently large signal when the soft magnetic material is excited, the excitation frequency must be increased (> 1 kHz).
There is a need to.

However, when the excitation frequency is increased, the pulse width becomes large, and it becomes necessary to greatly change the coercive force of each magnetic material in order to separate the pulses. As described above, it is difficult to obtain a plurality of magnetic materials having greatly different coercive forces, and even if such a magnetic material is obtained, a material having a large coercive force will be excited, and a strong magnetic material will be obtained. A magnetic field, that is, a strong excitation device is required. Of course, it is necessary to consider the influence of a strong magnetic field on the surroundings.

An object of the present invention is to make use of the large Barkhausen effect, so that the structure is simple and easy to manufacture
An object is to provide a multi-pulse magnetic marker whose operation is reliable.

[0011]

A large Barkhausen jump is a special phenomenon of an amorphous wire produced by a super-quenching technique or an amorphous ribbon heat-treated under twisting stress, and the magnetization reversal is a switch. It is characteristic that it progresses in a regular manner. Therefore, the magnitude (peak value and half width) of the pulse detected by the magnetization reversal accompanied by the large Barkhausen jump is independent of the excitation frequency and the excitation magnetic field intensity, and a sharp pulse can be obtained even when excited at a low frequency.

For this reason, the invention according to claim 1 of the present application is:
In a magnetic marker having a structure in which a plurality of magnetic wires or magnetic bands having a large Barkhausen effect are arranged in parallel, the individual magnetic materials constituting the marker are mutually magnetized in an externally applied excitation magnetic field. The magnetic bodies are arranged so as to be close to each other, and the magnetic bodies magnetically interfere with each other to output a pulse train corresponding to each of the magnetic bodies.

The invention according to claim 2 of the present application is characterized in that the plurality of magnetic bodies constituting the marker are magnetic bodies having substantially the same magnetic characteristics.

[0014]

The magnetic marker according to the present invention is made of a magnetic material having a large Barkhausen effect, and the magnetic material having the same effect takes only a binary state of magnetization. When they are arranged close to each other, the timing of the magnetization reversal is shifted due to magnetic interaction, and a plurality of pulses separated reliably are output by the number of magnetic bodies.

The magnetic interaction described here is explained as follows. As shown in FIG. 5, two magnetic bodies 1 and 2 having the same magnetic characteristics are arranged adjacent to each other, and as an initial state, the magnetic bodies 1 and 2 are magnetized from right to left in FIG. And When the external magnetic field Hex is applied from left to right in FIG. 5 and gradually increases in strength, at a certain critical point, one of the magnetic bodies 1 of the magnetic bodies 1 and 2 undergoes magnetization reversal to be in the state of FIG. .

In the state shown in FIG. 6, the magnetic flux leaking from the magnetic bodies 1 and 2 is closed between the magnetic bodies 1 and 2, and becomes metastable in energy. A larger external magnetic field Hex is required for the magnetic bodies 1 and 2 in the metastable state to reverse the magnetization to the state shown in FIG. That is, in order to reverse the magnetization of the magnetic body 2, a larger external magnetic field is required than when the magnetic body 2 exists alone.

The above is a description of the magnetic interaction used in the present invention. Due to this effect, the timing of the magnetization reversal can be reduced even in a magnetic material having very similar or the same coercive force. A magnetic marker having a shift and a plurality of pulses can be easily realized.

On the other hand, in a magnetic body having no large Barkhausen effect, when the magnetic bodies are arranged adjacent to each other, the magnetization advances as a single magnetic body, and the pulse is not separated.
It just grows.

[0019]

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

FIG. 1 shows an example of the configuration of a multi-pulse magnetic marker according to the present invention. Magnetic material 1 used for magnetic marker 11
Are amorphous wires made of FeSiB, which are magnetic materials that cause a typical large Barkhausen jump. Hereinafter, the magnetic material 12 is referred to as an iron-based wire 12.

Example 1 In Example 1, an iron-based wire having a diameter of 125 μm was used for 89 mm.
The two iron-based wires 12 are cut, and each iron-based wire 12 is brought into close contact with one magnetic marker 11.
Was configured. Similarly, three magnetic iron wires 12 cut as described above were used, and each magnetic iron wire 12 was adhered to form one magnetic marker 11. FIG. 2 shows the measurement results of the output signals of these two magnetic markers 11 and 11.

The excitation conditions are sine wave excitation with a frequency of 50 Hz and an amplitude of 80 A / m. As can be seen from FIG. 2, each magnetic marker 11 outputs two or three pulses according to the number of iron-based wires 12 constituting the magnetic marker.

Embodiment 2 In Embodiment 2, a two-pulse output type marker is formed by using the same two iron-based wires 12 as in Embodiment 1. FIG. 3 shows the result of examining the change in magnetic interaction by changing the distance d between the two iron-based wires 12.

The vertical axis in FIG. 3 represents the time interval Δt between the two output pulses. As the distance d between the two iron-based wires 12 increases, the effect of the interaction decreases.
The time interval Δt between the pulses is small. In the second embodiment, when the distance d between the iron-based wires 12, 12 exceeds 3 mm, the interaction between the iron-based wires 12, 12 decreases, and the number of pulses output from the magnetic marker 11 becomes one, It was output very close.

Comparative Example As a comparative example, FIG. 4 shows a measurement result of a magnetic marker constituted by using a wire having no large pulse Hausen jump. As is apparent from FIG. 4, the pulse is not separated in the comparative example, and the shape of the pulse increases as the number of wires increases.

The magnetic material used in the comparative example is an amorphous wire made of CoFeSiB, a high magnetic permeability material having a relative magnetic permeability exceeding 20,000, and does not have a large Barkhausen effect. The arrangement and dimensions of the magnetic material were adjusted so as to be the same as in the example.

As described above, a multi-pulse magnetic marker can be easily formed by using magnetic materials having a large Barkhausen effect adjacent to each other.

The present invention can be applied to a magnetic marker used for article detection in addition to an article identification magnetic marker having a large amount of information to improve the article detection accuracy (decrease the false detection rate).

[0029]

According to the present invention, by utilizing the large Barkhausen effect, a multi-bit magnetic marker having a simple structure and easy manufacture can be realized. Further, according to the present invention, since the magnetic wire or the magnetic band does not need to intentionally increase the coercive force of the magnetic material due to its characteristics,
Driving of the magnetic marker is enabled by a relatively small exciting magnetic field, and a magnetic marker which is easy to use can be obtained. Further, according to the present invention, it is not necessary to prepare a plurality of types of magnetic materials having clearly different coercive forces, and therefore, it is possible to easily configure a marker capable of identifying an article by counting the number of pulses. it can.

[Brief description of the drawings]

FIG. 1 is a partially cutaway perspective view showing a configuration of a multi-pulse magnetic marker according to the present invention.

FIG. 2 is a first embodiment of a multi-pulse magnetic marker according to the present invention.
FIG.

FIG. 3 is a second embodiment of the multi-pulse magnetic marker according to the present invention.
FIG.

FIG. 4 is a characteristic diagram of a comparative example.

FIG. 5 is an explanatory diagram for explaining an operation of the present invention.

FIG. 6 is an explanatory diagram for explaining the operation of the present invention.

FIG. 7 is an explanatory diagram for explaining the operation of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Magnetic body 2 Magnetic body 11 Magnetic marker 12 Magnetic material

Claims (2)

(57) [Claims] 1. A magnetic marker having a structure in which a plurality of magnetic lines or magnetic bands having a large Barkhausen effect are arranged in parallel, and each of the markers constituting the marker in an externally applied excitation magnetic field is provided. The multi-pulse type, wherein the magnetic bodies are arranged close to each other at a magnetically influenced distance, and the magnetic bodies magnetically interfere with each other to output a pulse train corresponding to each of the magnetic bodies. Magnetic marker. 2. The multi-pulse magnetic marker according to claim 1, wherein the plurality of magnetic materials constituting the marker are magnetic materials having substantially the same magnetic characteristics.