JPH11306275A - Article with identifying function and its identifying method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an article with an identifying function having many pieces of identification information to be used for identification, and its identifying method. SOLUTION: An article 5 to be identified is provided with magnetic element 1a, 1b, 1c and 2a, 2b. The magnetic elements 1a, 1b, 1c are constituted of a material to show large Barkhausen reversal, whereas the magnetic elements 2a, 2b are constituted of a material to show non-large Barkhausen reversal. Each of these magnetic elements is constituted by using a material with a different magnetic field intensity with which magnetism is reversed. An external magnetic field for identification is applied on the article 5 from a magnetic field applying means 3 and signals from each of the magnetic elements 1a, 1b, 1c and 2a, 2b are detected by a detecting means 4. Two kinds of external magnetic fields for identification with a different frequency are applied from the magnetic field applying means 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an article having an identification function such as a non-contact type IC card which can be identified in a non-contact manner using magnetism, and an identification method thereof.

[0002]

2. Description of the Related Art In recent years, as an alternative to a magnetic card, an IC card having a built-in integrated circuit such as a microcomputer and a memory has been used in various fields such as transportation, finance, medical care, and services. In particular, recently, a non-contact IC card which enables data transmission and reception with a data processing terminal device in a non-contact manner has been developed, and is expected to be extremely convenient.

[0003] With the widespread use of these IC cards, their unauthorized use has become a problem. I
As a method for preventing unauthorized use of the C card, a so-called software method for encrypting data has been mainly used, but a device that emits a special optical or electronic signal is built in. Things are also being developed.

As one of such systems, the inventors of the present application disclosed in Japanese Patent Application No. Hei 9-157512 that an article was measured by measuring the intensity of a magnetization reversal magnetic field of each magnetic element incorporated in the article. A method of identification was proposed. This is because a magnetic element that emits a signal that is not generally available and difficult to imitate is built into a small portable terminal such as an IC card, and when using it, an inquiry is made by applying an alternating magnetic field, By detecting a unique signal generated by a steep magnetization reversal by a magnetic element incorporated in a portable terminal, a small portable terminal is identified and security is ensured.

[0005] Since this device uses a magnetic element, it is advantageous in that signals can be detected in a non-contact manner, and can be used as a data carrier, an ID tag, and a transponder other than an IC card. Furthermore, lift tickets for ski resorts, management tags for sports clubs, access control of people,
It can be used for livestock management, sorting in production and sales, etc.

[0006]

By the way, in the above-described apparatus for detecting an abrupt magnetization reversal of a magnetic element and identifying an article, the intensity of a magnetization reversal magnetic field of each magnetic element incorporated in the article is measured. As a result, an article is identified, and a signal unique to each article can be obtained by combining a plurality of magnetic elements having different magnetization reversal magnetic field intensities. Therefore, in the above-described conventional device, the number of usable data depends on how many types of magnetic elements having different magnetization switching magnetic field intensities can be prepared. In common technology, this is 5
The number of usable data is not always sufficient, and there is a problem that applications are limited.

An object of the present invention is to provide an article having an identification function having a lot of identification information for identification.

Another object of the present invention is to provide an article identification method which can identify an article easily and without contact with high reliability.

[0009]

In order to achieve the above object, the invention according to claim 1 is directed to a magnetic element exhibiting a large Barkhausen inversion when an external magnetic field for identification is applied and a magnetic element for applying an external magnetic field for identification. And a magnetic element that does not exhibit large Barkhausen reversal.

Articles provided with the above magnetic element include I
A C card, a transponder, an ID tag, a data carrier, and the like are suitable, and are particularly suitable for wirelessly used articles such as a non-contact IC card.

The magnetic element may be in the form of a thin wire, a ribbon, a thin film, or the like. As the size, for example, in the case of a thin wire, a wire diameter of 10 μm to 200 μm is preferable, and a wire diameter of 20 μm to 100 μm can be more suitably used. For a thin ribbon, the thickness is preferably 5 μm to 50 μm, and more preferably 15 μm to 30 μm. 0.1μm for thin film
To 10 μm is preferable, and 0.5 to 5 μm is more preferable. Regarding the length of the magnetic element,
A length of 5 mm or more is suitable, but any length less than the length of the article to be identified is acceptable. As these magnetic elements, a magnetic material exhibiting large Barkhausen inversion and a magnetic material exhibiting no large Barkhausen inversion are used.

A magnetic material exhibiting a large Barkhausen reversal is:
It has a magnetic domain structure in which the magnetization is extremely stable in specific positive and negative directions. When the applied magnetic field intensity reaches a certain threshold, the magnetization is reversed all or part of the material at once. Therefore, in a large Barkhausen reversal magnetic field, an extremely steep magnetic pulse is radiated to the surroundings, and if a pickup coil or the like is arranged in the vicinity, a sharp voltage pulse with high intensity is induced. The major difference between the large Barkhausen reversal material and the general magnetic material is that the speed of the magnetization reversal at the moment when the applied magnetic field strength exceeds the threshold is hardly influenced by the change speed of the applied magnetic field. In the case of the inverted material, a large voltage is generated in the pickup coil even when excited at a low frequency.

[0013] Whether the magnetization reversal is a large Barkhausen reversal is generally determined based on analysis by magnetic measurement or dynamic domain observation in each frequency band from DC or extremely low frequency to high frequency. Is done.

However, depending on, for example, the degree of stability of the magnetic domain structure, even in a material exhibiting a pseudo-magnetization behavior that cannot be strictly described as a large Barkhausen inversion,
When a sharp magnetic pulse is generated around the periphery by the magnetization reversal and the intensity is hardly changed with respect to the frequency of the applied magnetic field, the material is also included in the large Barkhausen inversion material according to the present invention. Therefore, a series of materials generally called Wiegand wires can also be used as the large Barkhausen inversion material.

As a large Barkhausen reversal material, Ni
Fe alloys and their composites (Wiegand wires) can also be used, but amorphous alloy materials are particularly preferred. Among them, a linear amorphous alloy is preferable, and an amorphous alloy thin wire having Fe-based magnetostriction is one of particularly preferable ones.

As the non-large Barkhausen reversal material that does not exhibit large Barkhausen reversal, a magnetic material having a coercive force of at least 10 times or less the magnetization reversal threshold of the simultaneously used large Barkhausen reversal material is suitable. A so-called high-permeability material that reverses magnetization is suitable.

As such a material, a crystalline alloy such as iron, silicon steel, permalloy or alpalm can be used, but an amorphous alloy is preferable. As the form, a thin wire, a thin strip, or a thin film is used, but when the thin strip or the thin film is arranged close to the large Barkhausen inversion material, the effect of contributing to the improvement of the characteristics of large Barkhausen inversion is also obtained. is there.

According to a second aspect of the present invention, a magnetic element which exhibits large Barkhausen reversal when an external magnetic field for identification is applied and a magnetic element which does not exhibit large Barkhausen inversion when an external magnetic field for identification is applied are arranged on an article. In the meantime, a magnetic field having at least two kinds of frequencies is applied to the article as the external magnetic field for identification, thereby detecting a signal emitted to the surrounding when each of the magnetic elements reverses magnetization, and based on the signal, It is characterized by identifying the article.

That is, an article is identified by utilizing a difference in frequency dependence of magnetization reversal between the large Barkhausen reversal material and the non-large Barkhausen reversal material. The large Barkhausen reversal material has a threshold value for reversing the magnetization, and the magnetization reversal rapidly occurs at the moment the applied magnetic field strength exceeds the threshold value. Therefore, the change is discontinuous, the rate of change of the applied magnetic field,
That is, it does not depend much on the frequency. On the other hand, a non-large Barkhausen inversion material, which is a general magnetic material, largely depends on a change speed (frequency) of an applied magnetic field.

For this reason, in the case of high-frequency excitation, both the large Barkhausen inversion material and the non-large Barkhausen inversion material emit a large magnetic pulse signal, but the signal output of the non-large Barkhausen inversion material is low in low-frequency excitation. Because it drops. FIG. 1 shows the results of measuring the excitation frequency dependence of the signal output of the large Barkhausen inversion material and the non-large Barkhausen inversion material.

In this measurement, Co ₃₉ Fe having a wire diameter of 100 μmφ and a length of 80 mm was used as a large Barkhausen inversion material.
_As a non-large Barkhausen reversal material, a Co _68.15 Fe _4.35 Si _12.5 B ₁₅ (at.%) Amorphous material having a wire diameter of 123 μmφ and a length of 80 mm was used using a ₃₉ Si ₇ B ₁₅ (at.%) Amorphous metal thin wire. A thin metal wire was used. And 300m in length
These amorphous metal thin wires were inserted into the center of a measuring device in which a solenoid-type detection coil having a length of 150 mm and a number of turns of 567 was arranged at the center of a solenoid-type exciting coil having m and 560 turns.

An alternating current is supplied to the exciting coil from an HP-3324A synthesized function sweep generator manufactured by Hewlett-Packard Company.
At a frequency of 0 Hz to 50 kHz, 4 Oersted (O
e) A sinusoidal magnetic field was generated. The signal from the detection coil was amplified by a high-speed amplifier, and the pulse voltage induced in the detection coil by the magnetization reversal of the sample was measured using an HP-54110 digitizing oscilloscope manufactured by Hewlett-Packard Company.

FIG. 1 shows that the large Barkhausen reversal material and the non-large Barkhausen reversal material have greatly different dependencies on the excitation frequency, and the signal intensity difference between the two is extremely large especially at low frequencies.

From the above, at least two types of alternating magnetic fields having different frequencies are applied to the large Barkhausen inversion material and the non-large Barkhausen inversion material, and the signal output at each frequency is compared. It is possible to distinguish the signals of the inverted material and the non-large Barkhausen inverted material. That is, a signal derived from the large Barkhausen inversion element is detected by low-frequency excitation by setting an appropriate threshold value for the signal output intensity and discarded, and the large Barkhausen inversion element and the non-large Barkhausen inversion element are excited by high-frequency excitation. Signals from both sources can be detected.

In order to arrange the magnetic element as described above on an article, for example, the magnetic element may be sandwiched between adhesive labels, and the magnetic label may be attached to the article to be identified. Further, the above-described magnetic element may be incorporated in advance at the time of manufacturing the article to be identified.

[0026]

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

(First Embodiment) FIG. 2 shows one embodiment of the present invention. The article 5 to be identified includes a magnetic element 1
a, 1b and 1c and magnetic elements 2a and 2b are built in.
The magnetic elements 1a, 1b, 1c are made of a material exhibiting a large Barkhausen reversal.
Is composed of a material exhibiting non-large Barkhausen inversion. These have different magnetic field strengths for magnetization reversal. The article 5 from the magnetic field applying means 3
The detection means 4 detects signals from the magnetic elements 1a, 1b, 1c and the magnetic elements 2a, 2b. From the magnetic field applying means 3,
Two types of identification external magnetic fields having different frequencies are applied.
These two types of external magnetic fields for identification may be applied from the same magnetic field applying means, or may be separate magnetic field applying means.

These external magnetic fields for identification are alternately applied to the article 5 in different time zones. When applying from the same magnetic field applying means 3, frequency modulation may be performed. The signals detected by the detection means 4 are analyzed in time divisions tuned to the excitation frequency, and are compared for each frequency.

FIG. 3 is a schematic diagram of a signal captured by the detecting means 4. FIG. 3A shows the output voltage of the detecting means 4 in the time interval excited at a low frequency, and FIG.
Indicates the output voltage of the detection means 4 within the time interval excited at a high frequency.

In FIG. 3A, there are three distinct voltage pulses and two indistinct and extremely small voltage changes. The former is due to the magnetization reversal of the magnetic elements 1a, 1b, 1c made of a large Barkhausen inversion material, and the latter is due to the magnetic elements 2a, 2 made of a non-large Barkhausen inversion material.
This is due to the magnetization reversal of b.

On the other hand, in FIG. 3B excited at a high frequency, the magnetic element 2 made of a non-large Barkhausen inversion material is used.
Since the signal intensities from the signals a and 2b increase and become clear, five voltage pulses are observed. in this way,
By using a plurality of excitation frequencies, different identification codes can be generated.

(Second Embodiment) Another embodiment of the present invention is shown in FIG. In the present embodiment, as shown in FIG. 4A, a thin strip-shaped non-large Barkhausen inversion element 2 is disposed at both ends of a thin line-shaped large Barkhausen inversion element 1. The configuration as shown in FIG. 4A is in principle exactly the same as the first embodiment. Adopting such a configuration has an advantage that the performance of the large Barkhausen inversion material is improved.

That is, the large Barkhausen inversion is sensitively affected by the shape of the material, and if the length of the material is too short, the large Barkhausen inversion may be difficult to occur. However, if the configuration as shown in FIG. 4A is adopted, the large Barkhausen inversion element 1 having a short element length so that large Barkhausen inversion does not occur alone, but the soft magnetic non-large Barkhausen inversion element 2 Are arranged in close proximity,
Since large Barkhausen inversion is induced, the device can be downsized to improve performance.

In this embodiment, as shown in FIG. 4B, the large Barkhausen inversion element 1 in the form of a thin line is arranged on the non-large Barkhausen inversion element 2 in the form of a thin film. Is also good. In this case, when the easy magnetization direction of the non-large Barkhausen inversion element crosses the easy magnetization direction of the large Barkhausen inversion element at an angle close to perpendicular, the performance of the large Barkhausen inversion material is improved. When the second embodiment is compared with the first embodiment, the pulse generation characteristics of the non-large Barkhausen inversion material tend to be slightly inferior in the second embodiment. That is, in FIG. 4A, the demagnetizing field is increased due to the shape of the non-large Barkhausen inversion element, and in FIG. 4B, the easy magnetization direction of the non-large Barkhausen inversion material is changed to the easy magnetization direction of the large Barkhausen inversion material. Therefore, the steepness of the magnetization reversal tends to be slightly impaired. Therefore, when it is desired to generate a sharp voltage pulse from the non-large Barkhausen inversion material, the aspect ratio of the non-large Barkhausen inversion material is preferably equal to or more than の of the aspect ratio of the large Barkhausen inversion material.
Also, the intersection angle between the easy magnetization direction of the non-large Barkhausen inversion material and the easy magnetization direction of the large Barkhausen inversion material is 0
It is desired that the angle is not less than 40 ° and less than 40 °. 4A and 4B, the large Barkhausen inversion element 1
Has shown one, but it may have a plurality of large Barkhausen inversion elements.

[0035]

Embodiments of the present invention will be described below.

(Example 1) First, three amorphous metal thin wires were prepared as a large Barkhausen inversion type magnetic element provided for generating an identification signal on an article. These are Co ₃₉ Fe ₃₉ S having a wire diameter of 30 μmφ and a length of 15 mm.
i ₇ B ₁₅ are amorphous thin metal wire (atomic%) was achieved, thereby generating a large Barkhausen reversal in switching field intensity of each 0.6,1.4,2.5 Oersted (Oe). The large Barkhausen reversal field strength of these fine wires was measured as follows.

At the center of a solenoid type exciting coil having a length of 300 mm and 560 turns, a length of 150 mm and 5 turns
Each thin wire was inserted into the center of the measuring device in which the 67-turn solenoid type detection coil was arranged. An alternating current was supplied to the exciting coil from an HP-3324A synthesized function sweep generator manufactured by Hewlett-Packard Company, and a triangular magnetic field of 50 Hz, 4 Oersted (Oe) was generated. In the detection coil,
A Hewlett-Packard HP-54110 digitizing oscilloscope was connected, and the pulse voltage induced in the detection coil by the magnetization reversal of the sample was measured. As a non-large Barkhausen reversal type magnetic element, a wire diameter of 3
Co _68.15 Fe _4.35 Si _{12.5 with 0 μmφ} and 15 mm length
An amorphous metal fine wire of B ₁₅ (atomic%) was prepared.

Then, the adhesive was applied to one side and the length was 21 m.
m, width 10mm, thickness 25μm, thickness of adhesive 20μm
Between the two polyethylene terephthalate (PET) films of the above, the above-mentioned four amorphous metal fine wires are laminated,
A sample in the form of a label was prepared.

The label-like sample obtained as described above was measured by the above-described measuring system. Table 1 below shows the intensity of the induced voltage pulse accompanying the magnetization reversal of the element captured by the detection coil when a low-frequency magnetic field of 50 Hz was applied from the excitation solenoid coil.

[0040]

[Table 1] Excitation frequency = 50 Hz Magnetic field (Oe) Voltage pulse intensity (mV) 0.15 0.8 24 1.7 27 3.6 3.6 18

The applied magnetic field strength at which three sharp voltage pulses were generated almost coincided with the magnetization reversal threshold of each large Barkhausen reversal material. Also, a smaller magnetic field of 0.1
In (Oe), a low strength bump was observed, corresponding to the coercive force of the non-large Barkhausen inversion material. Thus, when excited at a low frequency, the intensity of the non-large Barkhausen inverting element is very weak as compared with that of the large Barkhausen inverting element, and if an appropriate trigger is set, three large Barkhausen inverting elements are used. It was easy to select and detect only the pulse signal of the inversion element.

Table 2 below shows induced voltage pulses associated with the reversal of the magnetization of the element captured by the detection coil when a high-frequency magnetic field of 5 kHz is applied.

[0043]

Table 2 Excitation frequency = 5 kHz Magnetic field (Oe) Voltage pulse intensity (mV) 0.1 248 0.9 243 1.8 288 3.8 210

As the excitation frequency became higher, the intensity of the voltage pulse accompanying the magnetization reversal of the non-large Barkhausen reversal material sharply increased, and became larger than that of the large Barkhausen reversal element. As described above, when excitation was performed at a high frequency, a signal from a non-large Barkhausen inversion element as well as a signal from a large Barkhausen inversion element could be detected.

As described above, by using a plurality of frequencies for excitation, a plurality of identification codes can be generated using the same element.

[0046]

As described above, according to the present invention, according to the present invention, the magnetic element arranged on the article is made of a special magnetic material, and the distinctive characteristic of the magnetic element is distinguished by the application of the external magnetic field for identification. Since a signal having a characteristic is output, it is difficult not only to forge a magnetic element but also to imitate a signal, and to secure high security against fraud and the like.

The first code is constituted by a signal from a magnetic element made of a large Barkhausen inversion material by low-frequency excitation, and the first code is constituted by a signal from a large Barkhausen inversion element and a non-large Barkhausen inversion element by high-frequency excitation. By adopting a method of configuring the two codes and combining them, the number of identifiable data can be dramatically increased.

Further, a low frequency excitation type identification system,
Prepare two types of high frequency excitation type identification system,
By generating two types of different signals from the same magnetic element by appropriately using them according to the application, it can be used for a plurality of applications.

According to the present invention, since the identification code of an article can be magnetically identified in a non-contact manner, it can be applied to a wide range of applications and has great industrial significance.

[Brief description of the drawings]

FIG. 1 is a measurement diagram showing a change in a voltage pulse depending on an excitation frequency of an amorphous thin line showing large Barkhausen inversion and an amorphous thin line not showing it.

FIG. 2 is an explanatory diagram of a first embodiment of an article having an identification function according to the present invention.

3A and 3B are schematic diagrams showing a difference in output waveform depending on an excitation frequency of the article of the embodiment shown in FIG. 2, wherein FIG. 3A is an output waveform when excited at a low frequency, and FIG. It is an output waveform when excited.

FIG. 4 is an explanatory view of a second embodiment of an article having an identification function according to the present invention, in which (a) shows two magnetic elements made of a thin-line large Barkhausen inversion material and a non-large Barkhausen inversion material; (B) shows an example in which a single thin film is used as a magnetic element made of a thin line-shaped large Barkhausen inversion material and a non-large Barkhausen inversion material.

[Explanation of symbols]

1, 1a, 1b, 1c Magnetic element made of large Barkhausen inversion material 2, 2a, 2b Magnetic element made of non-large Barkhausen inversion material 3 Magnetic field applying means 4 Detecting means 5 Article

Claims (2)

[Claims] 1. An identification comprising a magnetic element exhibiting a large Barkhausen inversion when an external magnetic field for identification is applied, and a magnetic element not exhibiting a large Barkhausen inversion when applied with an external magnetic field for identification. Articles with functions. 2. A magnetic element exhibiting a large Barkhausen reversal upon application of an external magnetic field for identification and a magnetic element not exhibiting a large Barkhausen reversal upon application of an external magnetic field for identification are arranged on an article. Applying a magnetic field having at least two types of frequencies as the external magnetic field for identification, thereby detecting a signal emitted to the surrounding when each of the magnetic elements reverses magnetization, and identifying the article based on the signal. An article identification method characterized by the following.