JPH08293012A - Information recording medium - Google Patents

Abstract

PURPOSE: To provide an information recording medium which can much increase the information quantity to be treated. CONSTITUTION: An amorphous magnetostrictive ribbon 12 is provided with the load means 14, 15 and 16 which control the magnetostrictive vibrations and vary the resonance frequency. Therefore, the different levels of resonance frequency are secured among ribbons 12 and many resonance point peaks can be used as data.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an information recording medium for reading information in a non-contact manner by detecting a higher resonance frequency of magnetostrictive vibration of an amorphous magnetostrictive ribbon, and more particularly to information to be recorded. It relates to a technique for increasing the amount.

[0002]

2. Description of the Related Art In recent years, information recording media capable of exchanging information in a contactless manner have been widely used in social life. For example, using an IC as an information recording medium,
A module for exchanging information between the IC and the antenna by electromagnetic waves in the RF band has been developed, and such a module is used for reading an individual identification (ID) card, a lift ticket, or the like, or physical distribution management. However, the IC-based system can handle a plurality of bits of information, but has a drawback of high manufacturing cost.

On the other hand, as the above information recording medium,
It is also known to use an amorphous magnetostrictive ribbon. Since magnetic materials are generally cheaper than semiconductors, the above information recording media are being widely used, for example, as shoplifting prevention tags attached to products displayed in stores. The shoplifting prevention tag is an information recording medium that handles 1-bit information, but in recent years, a tag that can handle multiple bits of information has been proposed (for example, International Publication WO92 / 12402).

FIG. 9 shows an example of the information recording medium according to the above proposal. In the information recording medium shown in this figure, an amorphous magnetostrictive ribbon 2 is arranged in a cavity 1a inside a casing 1 in a vibrating state. A magnetized semi-hard magnetic material (a material having a coercive force intermediate between the soft magnetic material and the hard magnetic material) 3 is attached to one side of the casing 1. In such an information recording medium, a bias magnetic field of the semi-hard magnetic material 3 is applied to the amorphous magnetostrictive ribbon 2, and when an alternating magnetic field is applied in that state, the amorphous magnetostrictive ribbon 2 vibrates.

That is, as shown in FIG. 10, when the alternating magnetic field AH is applied to the amorphous magnetostrictive ribbon 2 while the bias magnetic field BH is applied, the magnitude of the magnetostriction of the amorphous magnetostrictive ribbon 2 changes at a predetermined cycle. This causes magnetostrictive vibration. Then, the vibration of the amorphous magnetostrictive ribbon 2 is received as a signal S by the receiver. The receiver detects the resonance frequency existing in the signal S from the peak of the received signal (resonance point peak). In this case, since the detected resonance point peak depends on the length of the amorphous magnetostrictive ribbon, the information recording medium can be specified by detecting the resonance point peak.

The above is the basic principle of the information recording medium using the amorphous magnetostrictive ribbon 2. However, in the information recording medium according to the above proposal, a plurality of resonance frequencies included in the vibration of the amorphous magnetostrictive ribbon are used, It handles multiple bits of information. That is, in the proposed information recording medium, a predetermined portion along the longitudinal direction of the semi-hard magnetic material 3 is magnetized to write magnetic recording, thereby changing the bias magnetic field applied to the amorphous magnetostrictive ribbon 2, Select the order of the resonance peaks detected by the receiver. For example, if the receiver is tuned to detect signals at the first to fourth resonance frequencies,
Depending on the pattern to be written on the semi-hard magnetic material 3, a certain information recording medium detects only signals of primary and quaternary resonance frequencies, and a certain information recording medium detects only signals of primary and secondary resonance frequencies. In this way, it is possible to read 4-bit information from the first to fourth orders, even if they are separated by about 1 m.

[0007]

However, even in the above information recording medium, the information recording density is considerably smaller than that of the information recording medium using the IC. Therefore, the information recording medium has been considerably limited in its operation due to its low information amount. Therefore, it is possible to construct an information recording medium in which the resonance frequencies of the amorphous magnetostrictive ribbons are slightly different from each other by using a plurality of amorphous magnetostrictive ribbons. With this structure, if the number of amorphous magnetostrictive ribbons is n, the number of bits of information is n times as large as the above, and the recording density of the information recording medium is increased.

As described above, there has been a strong demand for increasing the recording density of the information recording medium, and the present invention aims to provide a new technique to meet such a demand.

[0009]

An information recording medium according to a first aspect of the present invention includes a support, a plurality of amorphous magnetostrictive ribbons oscillatingly provided on the support, and the amorphous material provided on the support. In an information recording medium comprising magnetic field applying means for applying a bias magnetic field to a magnetostrictive ribbon, and capable of reading data by detecting a plurality of resonance frequencies of magnetostrictive vibration of the amorphous magnetostrictive ribbon in an AC magnetic field. , On the amorphous magnetostrictive ribbon,
A load means for controlling the magnetostrictive vibration to change the resonance frequency is provided.

According to a second aspect of the present invention, in addition to the features of the first aspect, the load means suppresses the magnetostrictive vibration and reduces the resonance frequency. Further, the information recording medium according to claim 3 is characterized in that, in addition to the features according to claim 1 or 2, the loading means applies a different amount of load to each of the amorphous magnetostrictive ribbons.

[0011]

Next, the operation of the present invention will be described together with the characteristics of the magnetostrictive vibration of the amorphous magnetostrictive ribbon. The magnetostrictive vibration of the amorphous magnetostrictive ribbon has a plurality of resonance frequencies starting from the first order, and the relationship between the resonance frequency f _n and the order n is expressed by the following equation (1). However, in the equation (1), L is the length of the amorphous magnetostrictive ribbon, and v is the speed of sound transmitted through the amorphous magnetostrictive ribbon. f _n = nv / 2L (1)

FIG. 11 (b) is a diagram showing the relationship of the above equation (1). The resonance frequency f increases as the order n increases.
_n shows that it increases linearly. FIG. 11B
In the above, as an example, the order n is up to 4, but when using the resonance frequencies f _n from the 1st order to the 4th order, 4-bit information can be recorded.

Here, the sound velocity v in the equation (1) can be further expressed by the following equation (2). However, in the formula (2), E is the Young's modulus of the amorphous magnetostrictive ribbon, and ρ is the density. These values are unique to the material of the amorphous magnetostrictive ribbon, but by changing these two values, the resonance frequency f _n in equation (1) can be changed.
Can be changed. v = (E / ρ) ^1/2 (2)

In the information recording medium according to the first aspect, the amorphous magnetostrictive ribbon is provided with a load means for controlling the magnetostrictive vibration of the amorphous magnetostrictive ribbon to change the resonance frequency f _n. There is a way to make it bigger. For example, when the load is fixed to the amorphous magnetostrictive ribbon and its weight is increased, the resonance frequency f _n can be reduced. FIG. 11A shows the relationship between the order n and the resonance frequency f _n when the load is uniformly provided on the amorphous magnetostrictive ribbon and when it is not provided.

As shown in FIG. 11A, when a load is uniformly provided on the amorphous magnetostrictive ribbon, the resonance frequency f _n
Decreases at a constant rate, and the rate of decrease increases as the weight of the load increases. That is, the heavier the load, the more the resonance frequency f _n decreases. Thus, claim 1
In the above information recording medium, the resonance frequency f _n of the amorphous magnetostrictive ribbon can be controlled. By thus providing the amorphous magnetostrictive ribbons having different resonance frequencies f _n , it is possible to construct an information recording medium having many resonance point peaks that can be used as data. In the case of FIG. 11A, 4 × 2 = 8
It has a bit data capacity.

In the information recording medium according to a third aspect of the present invention, by applying different amounts of loads to the amorphous magnetostrictive ribbons, the resonance frequencies in the respective orders of the amorphous magnetostrictive ribbons are made different from each other. The number of data can be further increased.

[0017]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a side sectional view showing an information recording medium of an embodiment, and FIG. 2 is a sectional view taken along the line II-II in FIG. In FIG. 1, reference numeral 1 is a casing (support). Casing 1
Reference numeral 0 is made of synthetic resin such as plastic and has three recesses 10a, ... The openings of the recesses 10a, ... Are closed by semi-hard magnetic materials (magnetic field applying means) 11, ..., and the spaces formed by the semi-hard magnetic material 11 and the recesses 10a ,.
An amorphous magnetostrictive ribbon 12 slightly smaller than the shape of the concave portions 10a, ... Is accommodated in a freely vibrating state.

A predetermined magnetization pattern is recorded on the semi-hard magnetic material 11, which allows the amorphous magnetostrictive ribbon 1 to be recorded.
Bias magnetic field BH is applied to 2 (see FIG. 10). Then, in that state, the amorphous magnetostrictive ribbon 1
When the AC magnetic field AH is applied to 2, ..., Magnetostrictive vibration is generated in the amorphous magnetostrictive ribbon 12, and the vibration of the amorphous magnetostrictive ribbon 12 is transmitted as a signal S. The transmitted signal S is received by the receiver, which detects the resonance frequency present in the signal S by the peak of the received signal.

Here, as the semi-hard magnetic material 11, C
u-Ni-Fe alloy, Cu-Ni-Co alloy, Fe-C
r-Co alloy, Fe-Co-V alloy, Fe-Ni-Cr
A magnetic alloy such as an alloy, an Fe-Mn alloy, or a Co-Pt alloy drawn in a plate shape can be used. Also,
Rare earth-cobalt magnets such as R-Co5, Ba-ferrite magnets, Sr-ferrite magnets, alnico magnets, etc. can also be used. Further, magnetic powders used for magnetic tapes such as Ba-ferrite powder and Sr-ferrite powder are dispersed in a binder to form a liquid, which is coated on a plastic base material, or such a base. A material obtained by vapor deposition / sputtering of a magnetic material can also be used.

The semi-hard magnetic material 11 has a coercive force intermediate between those of the soft magnetic material and the hard magnetic material, so that the semi-hard magnetic material 11 can be magnetized and demagnetized partially or wholly. It is composed of materials that can In order to obtain the stability of magnetic recording, the coercive force of the semi-hard magnetic material is preferably 300 Oe or more, and is preferably 5000 Oe or less so that the magnetic recording can be easily erased. A more desirable range of coercive force is 1000 to 3000 Oe.

Next, the amorphous magnetostrictive ribbons 12, ...
Has a high magnetic permeability and is susceptible to magnetostriction Fe—Ni—Mo—
B system, Fe-B-Si system, Fe-B-Si-C system, Fe
It is manufactured by making an alloy such as —Co—B—Si system amorphized by a super-quenching method and forming it into a ribbon shape having a thickness of 10 to 50 μm. In this case, in order to improve the detection accuracy of the signal generated by the magnetostrictive vibration of the amorphous magnetostrictive ribbons 12, ..., Annealing in a magnetic field may be performed after the rapid cooling.

As shown in FIG. 2, the load bodies 14, ... Are fixed to one surface of the amorphous magnetostrictive ribbons 12 ,. In this embodiment, the load bodies 14, ... Are made of a plastic sheet having the same shape and size as the amorphous magnetostrictive ribbon 12, and are adhered to one surface of the amorphous magnetostrictive ribbon 12 by an adhesive material. The load bodies 14, ... Are selected to have a weight and Young's modulus that do not interfere with the magnetostrictive vibration of the amorphous magnetostrictive ribbon 12. For the same reason, the adhesive material is selected such that it does not cure and its hardness does not change depending on the ambient temperature.

The load body 14 fixed to the second amorphous magnetostrictive ribbon 12 from the top in FIG. 2 is composed of one plastic sheet, and the third load body 15 is two plastic sheets and the fourth. The load body 16 is composed of three plastic sheets. The load 1
As a method of providing 4, ..., A well-known surface treatment method such as a sputtering method or a vacuum deposition method can be used, or a coating material made of a synthetic resin can be applied.

In the information recording medium having the above structure, since the weights of the amorphous magnetostrictive ribbons 12, ... Are all different, their resonance frequencies are all different from the first order to the higher order. Therefore, a lot of data can be exchanged by processing the presence / absence of a peak of the received signal at those resonance frequencies as an on / off signal. Further, in this information recording medium, since the amorphous magnetostrictive ribbons 12 have the same length, the semi-hard magnetic material 11
The areas of the magnetization pattern to be written in are the same, and writing can be performed easily. Furthermore, since the length of the amorphous magnetostrictive ribbon that can be used is limited, the number of usable amorphous magnetostrictive ribbons is also limited when a plurality of amorphous magnetostrictive ribbons having different lengths are provided. There is no limit. Therefore, the data amount can be significantly increased by using many amorphous magnetostrictive ribbons.

Next, an experiment for confirming the operation of the present embodiment was conducted, which will be described. As an amorphous magnetostrictive ribbon, Me
tglas2826MB (made by Allied) length 80 mm, width 10
A piece cut into a size of mm and a thickness of 0.03 mm was used. A Cu—Ni—Fe alloy having a coercive force of about 350 Oe was used as the semi-hard magnetic material, and these were attached to a casing made of ABS resin.

Further, as the load body, a P having a thickness of 50 μm is used.
An ET sheet (manufactured by Toray) cut into a size of 80 × 10 mm was used. Then, this PET sheet was adhered to the amorphous magnetostrictive ribbon 12 with an adhesive material (Nystack NS-10S: made by Nichiban). The weight of the load consisting of the PET sheet and each one layer of the adhesive was 110 mg.
On another amorphous magnetostrictive ribbon, a PET sheet and an adhesive material each having two layers were formed. That is, PET adhered to an amorphous magnetostrictive ribbon with an adhesive material
A PET sheet was further adhered to the surface of the sheet with an adhesive material. Similarly, for other amorphous magnetostrictive ribbons,
A PET sheet and an adhesive material each having three layers were formed.
Then, an information recording medium was constructed for each amorphous magnetostrictive ribbon in this way, and the resonance frequency of the amorphous magnetostrictive ribbon was measured for each, and the results shown in Table 1 were obtained.

As is clear from the above results, the load was adhered to the amorphous magnetostrictive ribbon of the same shape, and these 4
When one information recording medium is composed of two amorphous magnetostrictive ribbons, four times as many resonance peaks as in the case of using one amorphous magnetostrictive ribbon can be used, and an information recording medium having a large amount of information can be structured. can do.

[0028]

[Table 1]

Next, FIG. 3 shows a second embodiment of the present invention in which a casing 20 is provided with various amorphous magnetostrictive ribbons 21 ,. That is,
The amorphous magnetostrictive ribbons 21 and 22 are made of the same material and have the same shape and size, but one amorphous magnetostrictive ribbon 22 is bonded with a load body 27 similar to that of the above-described embodiment. As a result, the resonance frequency of the amorphous magnetostrictive ribbon 22 is lower than the other resonance frequency. Further, the amorphous magnetostrictive ribbon 23 is made shorter than the amorphous magnetostrictive ribbons 21 and 22.
The resonance frequency of the amorphous magnetostrictive ribbon 23 is higher than the resonance frequency of the amorphous magnetostrictive ribbon 22. Further, the amorphous magnetostrictive ribbon 24 is made shorter than the amorphous magnetostrictive ribbon 23, so that the resonance frequency of the amorphous magnetostrictive ribbon 24 is higher than the resonance frequency of the amorphous magnetostrictive ribbon 23.
Also in such an information recording medium, since the resonance frequencies of the amorphous magnetostrictive ribbons 21, ... Are all different from the first order to the higher order, many resonance point peaks can be used as data, and more data can be obtained. Can interact.

The present invention is not limited to the above embodiment, but various modifications can be made as follows. As shown in FIG. 4, the load body 30 can be provided on a part of the amorphous magnetostrictive ribbon 12 in the longitudinal direction. In this case, the center of the load body 30 may be aligned with or displaced from the center of the amorphous magnetostrictive ribbon 12. As shown in FIG. 5, the load body 31 composed of a plurality of small pieces,
, May be scattered in the longitudinal direction of the amorphous magnetostrictive ribbon 12. In this case, the load bodies 31 having a uniform size may be evenly arranged on the amorphous magnetostrictive ribbon 12, or the amorphous magnetostrictive ribbon 12 may be arranged.
It is also possible to set a predetermined interval for obtaining the resonance frequency of. As shown in FIG. 6, two load bodies 32, 32 may be arranged at both ends of the amorphous magnetostrictive ribbon 12. As shown in FIG. 7, the cavity 40 of the casing 10 is filled with the liquid 40, and the liquid 40 is filled with the amorphous magnetostrictive ribbon 1.
2 may be immersed. Even with such a configuration, the vibration of the amorphous magnetostrictive ribbon 12 is suppressed, and the resonance frequency thereof can be reduced. As shown in FIG. 8A, the width of the load body 41 may be narrower than the width of the amorphous magnetostrictive ribbon 12. In that case, the position of the load body 41 may be at the center of the amorphous magnetostrictive ribbon 12, or may be arranged at a position deviated from the center of the amorphous magnetostrictive ribbon 12 as shown in FIG. Further, as shown in FIG.
The load bodies 41 may be bonded to both sides of the amorphous magnetostrictive ribbon 12.

[0031]

As described above, according to the present invention, many resonance point peaks can be used as data by controlling the vibration of the amorphous magnetostrictive ribbon.
The effect that more data can be processed is obtained.

[Brief description of drawings]

FIG. 1 is a side sectional view showing an information recording medium of a first embodiment.

FIG. 2 is a sectional view taken along line II-II of FIG.

FIG. 3 is a plan sectional view showing an information recording medium of a second embodiment.

FIG. 4 is a plan sectional view showing an information recording medium which is a first modification of the embodiment.

FIG. 5 is a plan sectional view showing an information recording medium that is a second modification of the embodiment.

FIG. 6 is a plan sectional view showing an information recording medium which is a third modification of the embodiment.

FIG. 7 is a plan sectional view showing an information recording medium which is a fourth modification of the embodiment.

FIG. 8 is a view showing a state in which a load is adhered to an amorphous magnetostrictive ribbon as viewed from the side, showing still another modified example of the embodiment.

FIG. 9 is a side sectional view showing a conventional information recording medium.

FIG. 10 is a diagram for explaining the principle of causing magnetostrictive vibration in an amorphous magnetostrictive ribbon, and is a diagram showing the strength of a magnetic field and the magnitude of magnetostriction.

FIG. 11 is a diagram showing the relationship between the order of vibration of an amorphous magnetostrictive ribbon and the resonance frequency, where (A) is a combination of an amorphous magnetostrictive ribbon with and without a load attached, and (B) is an amorphous magnetostrictive ribbon. The case of a ribbon alone is shown.

[Explanation of symbols]

 10 Casing (Support) 11 Semi-Hard Magnetic Material (Magnetic Field Applying Means) 12 Amorphous Magnetostrictive Ribbon 14, 15, 16 Load

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Ken Namikawa 4-33-9 Kugahara, Ota-ku, Tokyo

Claims (3)

[Claims] 1. A support, a plurality of amorphous magnetostrictive ribbons oscillatingly provided on the support, and magnetic field applying means provided on the support for applying a bias magnetic field to the amorphous magnetostrictive ribbon, In an information recording medium capable of detecting a plurality of resonance frequencies of magnetostrictive vibration of the amorphous magnetostrictive ribbon in an alternating magnetic field and reading data, the amorphous magnetostrictive ribbon is controlled to control the magnetostrictive vibration. An information recording medium comprising a load means for changing a resonance frequency. 2. The information recording medium according to claim 1, wherein the load means suppresses the magnetostrictive vibration to reduce the resonance frequency. 3. The information recording medium according to claim 1, wherein the loading means applies a different amount of load to each of the amorphous magnetostrictive ribbons.