JP2001160202A - SYSTEM OF PROCESSING MAGNETIC CARD USING MnBi MAGNETIC POWDER AND OTHER MAGNETIC POWDER EXCEPT IT, READ-OUT DEVICE AND PROCESSING METHOD - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a system of processing a magnetic card using MnBi magnetic powder and the other magnetic powder except it and capable of preventing accidents or unauthorized use and facilitating recording and reproduction. SOLUTION: The magnetic card processing system which consists of a recording device recording magnetic signals onto the magnetic card provided with at least one magnetic layer including MnBi magnetic powder and the other magnetic powder except it on a substrate and a read-out device reproducing the magnetic signals recorded on the magnetic card, is characterized in that the recording device is provided with a recording means for recording unrewritable fixed signals onto the MnBi magnetic powder which is in a demagnetized state and a recording means for recording rewritable signals onto the other magnetic powder except the MnBi magnetic powder and the read-out device is provided with a reproducing means for reproducing both the fixed signals recorded onto the MnBi magnetic powder and the rewritable signals recorded onto the other magnetic powder except the MnBi magnetic powder.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic card processing system, a reader and a processing method using MnBi magnetic powder and other magnetic powder.

[0002]

2. Description of the Related Art Magnetic recording media are easy to record and reproduce, so that they can be used for video tapes, floppy disks,
It is widely used as credit cards and prepaid cards. On the other hand, the feature that recording and reproduction are easy causes problems that the recorded data is easily erased by mistake and that the data can be easily falsified. In the case of a card, accidents such as erasure by a magnet with a strong magnetic field, which has recently been used for various doors and handbags, and data on a magnetic card being rewritten and misused, etc. Crimes are occurring frequently.

As a countermeasure, for example, an irreversible change is caused in a recording medium by a laser beam, such as an optical card, and once recorded, the recording medium cannot be rewritten, and it is difficult to falsify data. High security IC car
However, in the case of an optical card, an optical card is proposed.
An expensive device dedicated to an optical card for recording and reproducing a card is required, and an IC card has a drawback that the cost is high because a semiconductor is used. It has not been replaced with a magnetic card recording / reproducing device, and has not yet spread as expected.

For this reason, various measures have been proposed to prevent tampering of the magnetic card. For example, hologram printing or printing using advanced printing techniques is performed on the magnetic card. Although it can be effective in preventing the appearance of the card from forgery, the magnetic card
In the case of falsification of data written on the magnetic stripe of the card, the falsification may be performed, for example, by reading the data read from the credit card of another person into a regular credit card obtained by unauthorized means. This is performed by a method such as writing, and the written data is legitimate, so this cannot be prevented.

On the other hand, it is known that a magnetic recording medium using MnBi magnetic powder as a recording element has a feature that once recorded, it cannot be easily rewritten at room temperature (JP-B-52-46801; Kosho 54
-19244, JP-B-54-33725, JP-B-5
No. 7-38962, JP-B-57-38963, JP-B-59-31764), especially when magnetic card readers have become widespread throughout the world, data is accidentally erased. In credit cards, prepaid cards, etc., in which accidents and crimes frequently occur, such as being accidentally rewritten or intentionally rewritten, attention has been paid to prevent accidents and unauthorized use.

[0006]

In view of such circumstances, the present invention is characterized in that accidents and unauthorized use can be prevented by using other magnetic powders together with the above-mentioned MnBi magnetic powder. It is another object of the present invention to provide a magnetic card processing system, a reading device, and a processing method having a feature that recording and reproduction are easy.

[0007]

Means for Solving the Problems Mn used in the present invention
Bi magnetic powder is mainly composed of MnBi and has an average particle diameter of 0.
The coercive force measured by applying a magnetic field of 1 to 20 μm and 16 KOe is 3000 to 1500 at 300 K.
50-1000 Oe at 80 K at 0 Oe, 300 K
The magnetization amount measured by applying a magnetic field of 16 KOe is 20 emu / g to 60 emu / g at a temperature of 60 emu / g.
When left in an environment of 90 ° C. and a relative humidity of 90% for 7 days, the rate of decrease in the amount of magnetization is 40% or less, and the amount of metal Bi is expressed by the formula metal Bi / (MnBi + metal Bi) <0.5 Is the peak area from the (012) plane in the X-ray diffraction peak of Bi, and MnBi is M
It is the peak area from the (101) plane in the X-ray diffraction peak of nBi. ), And an MnBi magnetic powder in which an inorganic film is formed near the surface of the magnetic particles. The magnetic powder other than the MnBi magnetic powder used in the present invention includes gamma iron oxide magnetic powder, cobalt-containing iron oxide magnetic powder, Ba-ferrite magnetic powder, Sr-ferrite magnetic powder or metal mainly composed of Fe. Those having a coercive force at room temperature of about 250 to 3000 Oe, such as magnetic powder, are preferably used.

In the present invention, the magnetic recording medium using the MnBi magnetic powder contains the above MnBi magnetic powder in a magnetic layer and applies a magnetic field of 16 KOe to measure a coercive force of 5,000 to 16,000 Oe at 300K.
The magnetic flux density measured by applying a magnetic field of 100 to 1500 Oe at 0K and 16 KOe at 300K is 500
Magnetic recording in which the longitudinal squareness is 0.60 to 0.95 and the reduction rate of the magnetic flux density when left for 7 days in an environment of a temperature of 60 ° C. and a relative humidity of 90% is 50% or less. The magnetic recording medium is a medium further including a binder resin having a basic functional group and an additive having a basic functional group in the magnetic layer. Further, the magnetic recording medium is provided with a water-repellent layer, if necessary, on the surface of the magnetic layer or between the magnetic layer and the substrate. Further, in the present invention,
The magnetic recording medium using the MnBi magnetic powder and the other magnetic powder is a magnetic recording medium having a magnetic layer containing the normal magnetic powder together with the MnBi magnetic powder. In the present invention, these magnetic recording media are magnetic cards.

In the present invention, a magnetic card processing system using MnBi magnetic powder and other magnetic powder comprises the recording device and the reading device described in the embodiment, and cools the magnetic recording medium to a low temperature. Then, a signal is recorded using a magnetic head. When the magnetic recording medium is cooled to a low temperature to be in a demagnetized state, the magnetic recording medium is cooled to a low temperature or immediately after cooling.
An alternating magnetic field is applied to the magnetic layer to bring it into a demagnetized state. By this means, a non-rewritable fixed signal is recorded on the MnBi magnetic powder. Further, after recording the fixed signal, a rewritable signal is recorded on magnetic powder other than MnBI by means such as a method of recording again.

Further, according to the present invention, there is provided a magnetic recording medium recording / reproducing apparatus comprising: a magnetic recording medium reproducing apparatus for reproducing a signal magnetically recorded on the magnetic recording medium by a magnetic head; A magnetic recording medium reproducing apparatus provided with a magnetic field applying means for applying a direct current or an alternating magnetic field smaller than the coercive force of the MnBi magnetic powder in the magnetic layer. As shown in the examples, using this apparatus, a non-rewritable fixed signal and a rewritable signal are reproduced in advance, and after applying the magnetic field, the fixed signal is recorded on the MnBi magnetic powder by the reproducing means. The non-rewritable fixed signal and the rewritable signal recorded on the magnetic powder other than the MnBi magnetic powder can be reproduced.

In the present invention, a magnetic recording medium such as a magnetic card having a magnetic layer using a normal magnetic powder together with the above MnBi magnetic powder has a feature that once recorded, it is not easily erased at room temperature. By employing the processing system, the reading apparatus and the processing method of the present invention, it is possible to prevent tampering, which is a major problem in the magnetic card. That is, the present invention for recording and reproducing a fixed signal that cannot be rewritten on the MnBi magnetic powder and a signal that can be rewritten on other magnetic powders other than the MnBi magnetic powder has the ordinary magnetic property that recording and reproduction is easy. A magnetic card processing system, a reading device, and a processing method having both the characteristics of a recording medium and the characteristics of preventing accidents and unauthorized use.

More specifically, the magnetic recording medium containing the MnBi magnetic powder of the present invention has a coercive force of 10 at room temperature.
Although it is extremely high at about 000 Oe or more, at a temperature of about 100 K or less, it exhibits a peculiar property that the coercive force is reduced to about 1500 Oe or less. At room temperature, signals can be recorded using a magnetic head so that the recorded data cannot be easily rewritten at room temperature. Further, recording is performed by using a magnetic recording medium reproducing apparatus provided with a magnetic field applying means for applying a direct current or an alternating magnetic field smaller than the coercive force of the magnetic layer to the magnetic layer on the upstream side of the magnetic head of the magnetic recording medium reproducing apparatus. By reproducing, the data of the falsified magnetic recording medium obtained by copying the data of the magnetic recording medium cannot be reproduced, and only the data of the genuine magnetic recording medium can be reproduced. That is, M
Since a fixed signal that cannot be rewritten can be recorded / reproduced on the nBi magnetic powder, falsification becomes impossible.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail. As is clear from FIG. 1 showing the temperature dependency of the coercive force of MnBi magnetic powder as an example, the coercive force at room temperature is as high as about 12000 Oe, but decreases as the temperature decreases.
At 00K, it is 1500 Oe or less. Therefore, it can be demagnetized by cooling to a low temperature utilizing this property, and can be easily magnetized at room temperature after demagnetization.

FIG. 2 shows the initial magnetization curve of the magnetic recording medium using the MnBi magnetic powder. As shown in FIG.
It can be easily magnetized with a magnetic field as low as Oe. However, once the magnetic recording medium is magnetized, it becomes 140
It exhibits a high coercive force of about 00 Oe, making it almost impossible to erase or rewrite data thereafter.

FIG. 3 illustrates the erasing characteristics of a magnetic card using such a magnetic recording medium.
When a magnetic field of about 1000 Oe is applied, the magnetic field is almost completely demagnetized and the reproduction output becomes almost zero, indicating that the data of a normal magnetic card can be easily rewritten. That is, signals written in magnetic powders other than the MnBi magnetic powder can be rewritten.
On the other hand, in the magnetic card using MnBi magnetic powder, the output is 30% even when a magnetic field of about 5000 Oe is applied.
Even when a magnetic field of about 8000 Oe is applied, the output still remains about 50%, indicating that it is extremely difficult to rewrite data once it has been recorded. I have. That is, the signal written in the MnBi magnetic powder cannot be rewritten.

The MnBi magnetic powder used in the present invention is:
MnBi ingot is manufactured by powder metallurgy, arc furnace melting, high frequency melting, melt quenching, and the like, and is manufactured by pulverization. For example, in the case of manufacturing by powder metallurgy, an ingot is prepared. It is manufactured by dividing into a pulverizing step and a stabilizing step. It should be noted that MnBi magnetic powder may be used instead of the pulverization method.

The MnBi magnetic powder used in the present invention comprises:
The average particle diameter is in the range of 0.1 μm to 20 μm,
And the coercive force measured by applying a magnetic field of 16 kOe is 3
In the range of 3000-15000 Oe at 00K, 8
In the range of 50-1000 Oe at 0K and 3
The saturation magnetization measured by applying a magnetic field of 16 kOe at 00K is in the range of 20 to 60 emu / g.

The MnBi magnetic powder used in the present invention exhibits excellent corrosion resistance.
Even after holding for 7 days in an environment of 90 ° C and 90% relative humidity,
The deterioration rate is 40% or less. Further, Mn due to moisture
X-ray diffraction analysis of this magnetic powder, reflecting that decomposition into Bi and Bi was prevented, gave a temperature of 60 ° C. and a relative humidity of 90 ° C.
% After being maintained for 7 days in an environment of 0.5% or less, expressed as metal Bi / (MnBi + metal Bi). Furthermore, this magnetic powder not only shows excellent corrosion resistance under high temperature and high humidity, but also shows little deterioration of saturation magnetization even when immersed in a corrosive solvent such as sodium chloride solution or acetic acid solution. Show. Therefore, this M
A magnetic recording medium using nBi magnetic powder has high reliability.

In the present invention, MnBi as described above is used.
A magnetic recording medium using a magnetic powder is prepared in accordance with a conventional method. For example, a magnetic paint is prepared by mixing and dispersing a MnBi magnetic powder with a binder resin, an organic solvent, and the like, and applying the magnetic paint on a substrate. It is manufactured by drying to form a magnetic layer.

As the binder resin used herein, any of those generally used for magnetic recording media can be used. For example, a vinyl chloride-vinyl acetate copolymer, a polyvinyl butyral resin, a cellulose resin Resins, fluorine resins, polyurethane resins, isocyanate compounds, radiation-curable resins and the like are used.

The MnBi magnetic powder is easily corroded and decomposed in the presence of water, and is particularly prominent when the water is acidic. Therefore, when the MnBi magnetic powder is uniformly dispersed in the magnetic layer, the above binder resin is sufficient. However, in order to further improve the stability to moisture, the binder resin contains a basic functional group. Preferably. In particular, the MnBi magnetic powder improves the corrosion resistance by performing the above-described treatment, but the corrosion resistance can be further improved by further including a basic functional group in the binder resin. As the basic functional group, for example, imine, amine, amide, thiourea, thiazole, ammonium salt or phosphonium compound are suitable.

As a means for including a basic functional group in the magnetic layer, it is also effective to add an additive having a basic functional group. As the basic functional group contained in the additive, imine, amine, amide, thiourea, thiazole, ammonium salt, phosphonium compound and the like are suitable similarly to the binder resin.

Specifically, methylamine, ethylamine, propylamine, isopropylamine, butylamine, amylamine, hexylamine, heptylamine,
Octylamine, nonylamine, decylamine, undecylamine, dodecylamine, tridecylamine, tetradecylamine, pentadecylamine, cetylamine,
Aliphatic primary amines such as stearylamine, aliphatic secondary amines such as dimethylamine, diethylamine, dipropylamine, diisopropylamine, dibutylamine and diamylamine, trimethylamine, triethylamine, tripropylamine, tributylamine, triamylamine, triamylamine Aliphatic tertiary amines such as dodecylamine, as well as aliphatically unsaturated amines, alicyclic amines, aromatic amines and the like are preferably used. Furthermore, Si
Also, those obtained by modifying coupling agents such as Al and Ti with various amines can be used as suitable ones.

Generally, as the amount of the additive containing a basic functional group increases, the effect on the improvement of the corrosion resistance increases. However, when the amount is too large, the magnetic flux density of the magnetic layer decreases. Therefore, usually, the weight ratio to the magnetic powder is 1 to 1
The content is preferably about 5%, but it is particularly preferable to add about 4 to 10% by weight as a range that is highly effective in improving the corrosion resistance without significantly lowering the magnetic flux density of the magnetic layer.

As the organic solvent, conventionally used organic solvents such as toluene, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, tetrahydrofuran, and ethyl acetate are used alone or in combination of two or more. In addition, for the reasons described above, it is preferable to remove water dissolved in these organic solvents as much as possible before use. preferable.

In the magnetic coating material, various commonly used additives such as a dispersant, a lubricant, an antistatic agent and the like may be optionally added and used. However, if an acidic substance is present, MnBi may be used. The magnetic powder tends to deteriorate. Therefore, it is preferable from the viewpoint of corrosion resistance that the amount of the acidic lubricant that is generally used for the magnetic recording medium is reduced as much as possible.

The content ratio of the magnetic powder must be such that the volume ratio of the magnetic powder in the magnetic layer is 5 to 60%, and if this ratio is small, the output of the magnetic recording medium is low. And at the same time, the corrosion resistance is reduced.
If the volume ratio of the magnetic powder is too small, the cause of the decrease in corrosion resistance is unknown. Expected to decline. On the other hand, if the volume ratio of the magnetic powder is too large, the dispersibility of the magnetic powder becomes poor and the orientation of the magnetic powder decreases, and at the same time, the effect of embedding the magnetic powder with the binder resin becomes insufficient and the corrosion resistance decreases. . As described above, the occupied volume ratio of the MnBi magnetic powder in the coating film not only affects the magnetic characteristics and recording characteristics as in the case of the ordinary magnetic recording medium, but also has a problem unique to the coating film using this magnetic powder. It also affects the point of corrosion resistance.
Therefore, in order to obtain a coating film excellent not only in magnetic properties and recording properties but also in corrosion resistance, the volume ratio of the magnetic powder is 5 to 60.
%, It is necessary to design it to be 10% to 50%, and it is more effective to improve the corrosion resistance.

As described above, the MnBi magnetic powder is mixed and dispersed together with a binder resin, an organic solvent and the like to prepare a magnetic paint, and the magnetic paint is applied to a substrate such as a polyester film by an arbitrary application means, and dried. When forming a magnetic layer by applying a magnetic coating material onto a substrate, it is preferable to perform magnetic field orientation parallel to the magnetic layer surface, and the magnetic field strength is preferably about 500 to 3000 Oe.

When the magnetic layer is formed in this manner, 16
The coercive force measured by applying a magnetic field of kOe is 300K
At a temperature of 5000 to 16000 Oe,
When the magnetic flux density Bm measured by applying a magnetic field of 16 kOe at a temperature of 0 K in a range of 100 to 1500 Oe and applying a magnetic field of 16 kOe at 300 K is in a range of 500 to 2500 G,
A magnetic recording medium having a rectangular shape Br / Bm in the longitudinal direction of 0.60 to 0.95 is obtained.

When applied to a magnetic card, it is applied on a substrate on which a release layer has been applied in advance. The release layer is made of a conventional resin such as a silicone resin.
Synthetic resin materials having poor surface activity used for release layers such as tapes, seals and sheets can be used. As the thickness
0.1 to 2.0 μm is appropriate.

In order to further improve the corrosion resistance and chemical resistance of the magnetic layer containing the MnBi magnetic powder, it is preferable to further provide a water-repellent layer made of a water-repellent resin between the release layer and the magnetic layer. As the water repellent resin, polyvinylidene chloride resin, ethylene-vinyl alcohol-based polymer,
A fluorine resin, a vinylidene fluoride resin, an acrylic resin, or the like can be used. The thickness of the water-repellent layer is preferably 0.5 to 10 μm. If the thickness is smaller than this, a sufficient water-repellent effect cannot be obtained. On the other hand, if the thickness is too large, the spacing loss increases. Output decreases.

The magnetic recording medium produced in this manner exhibits excellent corrosion resistance, and has a temperature of 60 ° C. and a relative humidity of 90%.
The reduction rate of the magnetic flux density when left for 7 days in the above environment is 50% or less. Further, even when immersed for 24 hours in a 5% acetic acid aqueous solution under extremely severe corrosion conditions, the reduction rate of the magnetic flux density becomes 80% or less. Further, the magnetic recording medium is cooled to a low temperature, demagnetized, and
The magnitude of the magnetic flux density when a magnetic field of 500 Oe is applied is 50% or more of the saturation magnetic flux density at 300K.

By using such MnBi magnetic powder in combination with other magnetic powders, that is, other magnetic powders other than MnBi magnetic powder, there is no conventional magnetic recording medium utilizing the properties of MnBi magnetic powder. It is possible to provide a magnetic recording medium having unique characteristics.

In this case, the magnetic powder other than the MnBi magnetic powder to be mixed includes gamma iron oxide magnetic powder, cobalt-containing iron oxide magnetic powder, Ba-ferrite magnetic powder, Sr
-Ferrite magnetic powder or metallic magnetic powder mainly composed of Fe, having a coercive force at room temperature of about 250 to 3000 Oe is preferably used. The advantages of using these magnetic powders mixed with the MnBi magnetic powder are roughly divided into the following four points.

Since these magnetic powders generally have a higher saturation magnetization than the MnBi magnetic powder, the magnetic recording medium has a higher magnetic flux density than when the MnBi magnetic powder is used alone, and a high output is easily obtained. . When the oxide magnetic powder is mixed, these magnetic powders have no problem of corrosion, so that the corrosion resistance of the magnetic recording medium is further improved. By mixing the MnBi magnetic powder with another magnetic powder having a low coercive force, it is possible to maintain the characteristic that data falsification is difficult,
The data write current value can be reduced. As will be described in detail later, when recording data, different data is overwritten on the same rack, and a filter is used during reproduction.
The data can be multiplex-recorded by separating and reproducing the data.

Even when the MnBi magnetic powder and the above-mentioned magnetic powder are mixed and used, the preparation of the magnetic paint is basically the same as when the MnBi magnetic powder is used alone. However, it is preferable to adjust the dispersion means of the magnetic powder, the magnetic field orientation strength, and the like to some extent depending on the type and mixing amount of the magnetic powder to be mixed. The mixing ratio of MnBi magnetic powder and these magnetic powders is 1: 9 to
7: 3, and when the mixing ratio of the MnBi magnetic powder and the other magnetic powder is larger than this ratio, MnBi
The advantages described above are less likely to be exhibited as compared with the case where the i-magnetic powder is used alone, and when the i-magnetic powder is too small, once the data is recorded, it is the most significant feature of the magnetic recording medium using the MnBi magnetic powder. Features that are not erased are lost.

Further, as a magnetic recording medium, a magnetic layer using MnBi magnetic powder, a gamma iron oxide magnetic powder,
Containing iron oxide magnetic powder, Ba-ferrite magnetic powder, Sr
-A magnetic layer using ferrite magnetic powder or metal magnetic powder mainly composed of Fe may be laminated. The advantage of such lamination is basically that the above-described MnBi magnetic powder and other magnetic It is the same as the case of mixing and using a powder.

In particular, a magnetic recording medium having such a laminated magnetic layer has a rewritable data on one magnetic recording medium.
There is a feature that two types of data can be written, that is, data that is extremely difficult to rewrite once data is written.

For example, a magnetic layer using MnBi magnetic powder is formed in a stripe shape, and gamma iron oxide magnetic powder, Co-containing iron oxide magnetic powder, Ba-ferrite magnetic powder, Sr-ferrite When a magnetic layer using a magnetic powder or a metal magnetic powder mainly composed of Fe is applied, the portion where the magnetic layer using the MnBi magnetic powder is not laminated is rewritten in the same manner as a normal magnetic recording medium. Can be. However, MnBi
Although data can be easily written in a portion where a magnetic layer using a magnetic powder and a magnetic layer using another magnetic powder are stacked, rewriting becomes extremely difficult. Such features cannot be realized with conventional magnetic recording media,
Such a configuration using MnBi magnetic powder can be realized only for the first time.

The thickness of the magnetic layer in the case of laminating in this manner is, for example, about 2 to 20 μm for both upper and lower layers when applied to a magnetic card, and the total thickness is 3 to 3 μm.
It is preferably about 0 μm. If the thickness is too small, the output will be small, resulting in low card reliability. On the other hand, if the thickness is too large, it becomes difficult to record uniformly on the entire magnetic layer, and the error rate increases during data reproduction. In this case, it is also possible to use a combination of the above-described various methods, such as forming the above-described water-repellent resin layer on the surface of the magnetic layer or inserting the layer between two kinds of laminated magnetic layers. .

When a magnetic card is manufactured as a magnetic recording medium formed in this manner, the above magnetic paint is applied while magnetically orienting on a base film on which a release layer has been applied in advance. And dry. If necessary, an adhesive layer is applied on the magnetic layer thus produced. As the adhesive layer, usually a heat-fusible adhesive such as urethane resin and acrylic resin is preferably used,
Adhesives such as isocyanate-curable and UV-curable adhesives can also be used. Even without using this adhesive, it is also possible to heat-seal the card substrate using the resin of the magnetic layer.

When a water repellent layer is provided for the purpose of further improving the corrosion resistance and water resistance of the magnetic layer, a water repellent layer made of a water repellent resin is further provided between the release layer and the magnetic layer.
When this water-repellent layer is used, the general structure is a base-base film, a release layer, a water-repellent layer, a magnetic layer, and an adhesive layer. Of course, it is of course possible to use a combination of techniques commonly used for magnetic cards, such as forming an opaque layer such as a color layer between the release layer and the magnetic layer.

After slitting the magnetic tape of the magnetic recording medium formed as described above to a predetermined width, the adhesive layer side is overlaid on a magnetic card substrate or the like, and the heating roll is placed thereon. The adhesive layer is temporarily adhered to the card substrate surface by a method such as pressing with a stirrer, and then the base film is peeled off. The adhesive layer, the magnetic layer, Embedding the release layer in the substrate,
It is also produced by punching into the shape of a card.

The magnetic recording medium manufactured in this manner is initialized and recorded / reproduced. First, the magnetic recording medium using MnBi magnetic powder is initialized when the MnBi magnetic powder is extremely large at room temperature. While having coercive force, 1
The coercive force is remarkably reduced when cooled to a low temperature of about 00K or less.
At a temperature of about K or less, 300 to 30
In this step, a magnetic recording medium is demagnetized by applying an alternating magnetic field of 00 Oe. Such initialization may be performed while the tape is running in the state of a magnetic tape, or may be performed in a batch manner while being wound on a reel. Of course, it is also possible to perform the operation as a magnetic card.

The data recording method itself is not particularly different from a normal magnetic recording method. For example, when applied to a magnetic card, an encoder for a magnetic card or a magnetic card can be used. Data can be recorded using a card writer. A magnetic recording medium using MnBi magnetic powder, unlike other magnetic recording media, makes it extremely difficult to erase or rewrite data once data is recorded. That is, a fixed signal that cannot be rewritten can be recorded and reproduced.

At this time, when the MnBi magnetic powder and the other magnetic powder are mixed and used, or when the magnetic layer using the MnBi magnetic powder and the magnetic layer using the other magnetic powder are laminated and used, In the case of multiplex recording, data recording is performed at least twice.

The order is as follows. First, fixed data that cannot be rewritten (A: fixed signal that cannot be rewritten) is recorded using a writer (recording device). In this state, the same data (A: non-rewritable fixed signal) is recorded on the MnBi magnetic powder and on the magnetic powder other than the MnBi magnetic powder. The recording magnetic field at this time depends on the coercive force of another magnetic powder used together with the MnBi magnetic powder.
It is preferable that the recording magnetic field be as high as possible as long as the magnetic powder other than the magnetic powder does not demagnetize. This is a phenomenon peculiar to the magnetic recording medium using the MnBi magnetic powder, and is based on a phenomenon that the higher the recording magnetic field, the higher the coercive force of the magnetic recording medium.

Next, rewritable data (B: rewritable signal) is recorded over the same track. At this time, non-rewritable fixed data (A: non-rewritable fixed signal) and rewritable data (B: rewritable signal) are recorded at different recording densities. As the recording density at this time, generally, rewritable data requires a larger recording capacity than fixed data, so that rewritable data can be used for fixed data. It is preferable to increase the recording density of the data by 3 to 100 times. In addition,
The magnetic field from the data (A: fixed signal that cannot be rewritten) and the magnetic field from the data (B: rewritable signal) are prevented from interfering with each other, and the data is separated and reproduced using a filter or the like. For this purpose, it is necessary to make the recording density different in this way. In terms of separability, the larger the difference in recording density is, the more preferable. However, in order to increase the amount of data (A: non-rewritable fixed signal), the difference is preferably about 100 times or less.

In general, it is preferable to form low-density data in a lower layer of a magnetic recording medium and high-density data in an upper layer. This is because the higher the recording density, the greater the effect of the spacing loss between the magnetic head and the magnetic recording medium. Therefore, it is preferable that the data with a higher recording density be arranged closer to the magnetic head.

By such multiplex recording, first, data (A: non-rewritable fixed signal) is recorded over the entire magnetic layer, and then data (B: rewritable signal) is overwritten. Then, magnetic powder other than the MnBi magnetic powder or a magnetic layer using the magnetic powder is rewritten into data (B: rewritable signal). On the other hand, M
A magnetic layer using nBi magnetic powder or MnBi magnetic powder has a coercive force of 100 at room temperature once data is recorded.
Since it is extremely large, ie, 00 Oe or more, data recorded later
The data (B: rewritable signal) is not recorded, and only the previously recorded fixed data (A: non-rewritable fixed signal) remains recorded.

When a non-rewritable (A: non-rewritable fixed signal) is recorded and then a DC magnetic field is applied,
This (A: non-rewritable fixed signal) is further stabilized against an external magnetic field. The magnetic field at this time is 3000
It is preferably about 10,000 to 10,000 Oe. After that, the data (B:
By recording the rewritable signal) by the above-described method, the fixed data (A: non-rewritable fixed signal) and the rewritable data (B: rewritable signal) are recorded on the same track. be able to.

Further, when a magnetic layer using MnBi magnetic powder and a magnetic layer using another ordinary magnetic powder are laminated,
Two types of data can be written on one magnetic recording medium: rewritable data and data that is extremely difficult to rewrite once it has been written.

For example, a magnetic layer using MnBi magnetic powder is partially formed in a stripe shape, and gamma iron oxide magnetic powder, Co-containing iron oxide magnetic powder, and Ba-ferrite magnetic powder are covered so as to cover the magnetic layer. Then, a magnetic layer using Sr-ferrite magnetic powder or metallic magnetic powder mainly composed of Fe is applied. Data written in a portion where a magnetic layer using MnBi magnetic powder and a magnetic layer using another magnetic powder are stacked becomes extremely difficult to rewrite.
Data can be rewritten in the non-laminated portions in the same manner as in a normal magnetic recording medium.

As a data recording method, first, fixed data that cannot be rewritten (a: fixed signal that cannot be rewritten)
Is recorded by a usual method in a portion where a magnetic layer using MnBi magnetic powder and a magnetic layer using another magnetic powder are laminated. Even if the recorded data (a: fixed signal that cannot be rewritten) is to be rewritten with other data (b: falsified signal) for falsification, the data is recorded on the magnetic layer using MnBi magnetic powder. Since the data (a: fixed signal that cannot be rewritten) cannot be rewritten, the data of (a: fixed signal that cannot be rewritten) and (b: falsified signal) are reproduced during reproduction.
The two types of signals coming from the data are mixed, so that the data is destroyed and cannot be reproduced by a normal reader. The fixed data (a: non-rewritable fixed signal) includes, for example, the date of card issuance when applied to a magnetic card.
Record data that should not be rewritten, such as the issuer and card owner ID.

On the other hand, a portion consisting of only a magnetic layer using a magnetic powder other than the MnBi magnetic powder has a rewritable data.
(C: rewritable signal). This data (c: rewritable signal) can be arbitrarily rewritten each time it is used, as in a normal magnetic recording medium.

The above description has been given by taking as an example a mixed magnetic layer using MnBi magnetic powder and another magnetic powder, and a magnetic layer in which magnetic layers using these magnetic powders are laminated, respectively. Of course, various combinations can be used. For example, when applied to a magnetic card, the above laminated magnetic layer is formed on one side of the card, and a normal magnetic layer using iron oxide magnetic powder or barium ferrite magnetic powder is formed on the other side. Forming is also possible.

The reproduction of data is not particularly different from a normal magnetic recording medium reproducing method, and can be reproduced using a normal magnetic head. For example, a magnetic card can be reproduced using a magnetic card reader.

On the other hand, the reproduction of the multiplex-recorded data described above will be described in detail in the embodiment. However, a signal read by a magnetic head is passed through a band-pass filter and passed through a band-pass filter to obtain two types of data (different in recording density). A: A (non-rewritable fixed signal) and (B: a rewritable signal) are separated and reproduced.
The band width of the band-pass filter is set to +100 around the frequency corresponding to the recording density to be normally reproduced.
%, It is preferable to set the width to about -50%, but it is possible to change this width according to the required S / N.

The case where the present invention is applied to a magnetic card has been described above as an example.
Data that can be rewritten in the same manner as a normal magnetic recording medium.
It is needless to say that the present invention can be applied not only to a magnetic card but also to all magnetic recording media such as a magnetic tape and a floppy disk as an application in which data is recorded on a single magnetic recording medium by multiplex recording.

As described above, a magnetic recording medium (for example, a magnetic card) using MnBi magnetic powder has a property that once data is recorded, it is not easily erased at room temperature, that is, the recorded data is easily falsified. However, the data recorded on this magnetic card can be easily read by the same method as a normal magnetic card.
It is conceivable that the data of this magnetic card is copied to another normal magnetic card, and this card is illegally used as an intrinsic card.

For this reason, a reproducing method and an apparatus for reproducing data only from an intrinsic magnetic recording medium using MnBi magnetic powder are required.
Data recorded on a magnetic recording medium using nBi magnetic powder
Before reproducing the data, a DC or alternating magnetic field smaller than the coercive force of the magnetic layer is applied to the magnetic layer by, for example, a permanent magnet or a magnetic head for applying a magnetic field.

A case where the present invention is applied to a magnetic card will be described as an example. A magnetic card using MnBi magnetic powder is not easily erased at room temperature once data is recorded. Even if a magnetic field is applied, the data can be reproduced with almost no influence. On the other hand, a normal magnetic car
In magnetic recording, the data is erased or destroyed by the magnetic field and cannot be read. Therefore, even if the card using the MnBi magnetic powder is copied, the data of the copied card cannot be reproduced. Absent.

The strength of the magnetic field needs to be smaller than the coercive force of the magnetic layer using the MnBi magnetic powder and larger than the coercive force of the magnetic layer using the ordinary magnetic powder. The strength of the magnetic field is determined by applying a magnetic field of 500 to 1000 Oe to a magnetic layer using, for example, gamma iron oxide magnetic powder or Co-containing iron oxide magnetic powder.
Card data is almost erased and cannot be read. On the other hand, data is almost erased by applying a magnetic field of about 3000 Oe to a magnetic layer using Ba-ferrite magnetic powder or Sr-ferrite magnetic powder. Therefore, it is preferable that the range of the applied magnetic field be 500 to 5000 Oe. Even if a magnetic field within this range is applied,
The data recorded on the magnetic layer using the MnBi magnetic powder is hardly affected, so that the data can be read accurately.

Such a magnetic field may be either a DC magnetic field or an alternating magnetic field, and the means is not particularly limited as long as the magnetic field having the above-mentioned strength is generated. For example, when applying a DC magnetic field, a permanent magnet may be provided between the magnetic head for data reproduction and the card insertion slot. When an alternating magnetic field is applied, the magnetic head for reproduction is
A magnetic head for applying an alternating magnetic field may be provided between the insertion holes. It is also possible to apply a direct current or an alternating magnetic field to the magnetic card using a reproducing magnetic head, insert the magnetic card again, and read the data with this magnetic head.

On the other hand, when the reproducing method and the reproducing apparatus of the present invention are used, not only the magnetic card intended for unauthorized use but also the data of the ordinary magnetic card may be erased by mistake. . However, such troubles are usually caused by magnetic cards.
Do not insert the card, or take measures such as ejecting the magnetic card before applying a magnetic field.
This can be prevented by adding identification information to the password.

This identification information can be realized, for example, by providing a cutout or a small hole in a part of the magnetic card to make it different in shape from a normal magnetic card. When inserted into the reproducing apparatus, the notch or the pore is detected, for example, optically or mechanically, and the magnetic card having the notch or the pore is permitted to be inserted, and the notch or the pore is detected. The missing magnetic card is ejected from the playback device.

Further, the card surface is printed with an ink containing a phosphor excited by infrared rays or ultraviolet rays, the phosphor is excited by infrared rays or ultraviolet rays, and the fluorescence emitted from the identification mark is detected. Can also be identified.

The magnetic card processing system of the present invention comprises:
A recording device for recording a magnetic signal on a magnetic card provided with at least one magnetic layer containing a MnBi magnetic powder and another magnetic powder on a substrate, and a reading device for reproducing the recorded magnetic signal. What is claimed is: 1. A magnetic card processing system, wherein said recording device is a demagnetized MnBi.
Recording means for recording a non-rewritable fixed signal on the magnetic powder; and recording means for recording a rewritable signal on another magnetic powder other than the MnBi magnetic powder, and the above-described reading device reads the MnBi magnetic powder. A reproducing means for reproducing both the recorded fixed signal and the rewritable signal recorded on magnetic powder other than the MnBi magnetic powder is provided.

In the present invention, particularly, the magnetic layer
A magnetic card processing system comprising a magnetic layer containing only MnBi magnetic powder and a magnetic layer containing magnetic powder other than MnBi magnetic powder;
A magnetic card processing system comprising a magnetic layer containing both nBi magnetic powder and another magnetic powder, and a non-rewritable fixed signal and a rewritable signal are recorded on the same or different tracks. And the recording density of the rewritable signal is 3 to 3 times the recording density of the non-rewritable fixed signal.
And a processing system for the magnetic card which is 100 times larger.

A magnetic card reader according to the present invention is a magnetic card reader having at least one magnetic layer containing MnBi magnetic powder and other magnetic powder on a substrate. Reproducing means (reading means) for reproducing a non-rewritable fixed signal recorded on the magnetic powder, and reproducing means (reading means) for reproducing a rewritable signal recorded on magnetic powder other than the MnBi magnetic powder. ).

In the present invention, particularly, the magnetic layer
The magnetic card reader having a configuration in which a magnetic layer containing only MnBi magnetic powder and a magnetic layer containing magnetic powder other than MnBi magnetic powder are stacked;
A reading device for the magnetic card, comprising a magnetic layer containing both nBi magnetic powder and another magnetic powder, and a non-rewritable fixed signal and a rewritable signal recorded on the same or different tracks. And the recording density of the rewritable signal is 3 to 3 times lower than the recording density of the non-rewritable fixed signal.
It is possible to provide a magnetic card reader having a magnification of 100 times.

Further, the method for treating a magnetic card according to the present invention is a method for treating a magnetic card in which at least one magnetic layer containing a MnBi magnetic powder and another magnetic powder on a substrate is provided. A non-rewritable fixed signal is recorded on the magnetic powder, and a rewritable signal is recorded on other magnetic powders other than the MnBi magnetic powder, and the authenticity of the magnetic card is determined based on the fixed signal, Another signal different from the rewritable signal is newly recorded in the area where the rewritable signal is recorded after the determination of the authenticity.

In the present invention, particularly, the magnetic layer
The magnetic card processing method described above, wherein a magnetic layer containing only MnBi magnetic powder and a magnetic layer containing other magnetic powders other than MnBi magnetic powder are laminated.
The magnetic card processing method comprising a magnetic layer containing both i-magnetic powder and other magnetic powder, and a non-rewritable fixed signal and a rewritable signal are recorded on the same or different tracks. And a method for processing the magnetic card wherein the recording density of a rewritable signal is 3 to 100 times the recording density of a fixed signal which cannot be rewritten. .

[0074]

Next, an embodiment of the present invention will be described in more detail. Example 1 << Synthesis of MnBi magnetic powder >> For producing a magnetic card, MnBi magnetic powder synthesized by the following method was used.

(1) Preparation of MnBi Ingot Mn flake (purity: 99.9%, manufactured by Furuuchi Chemical Co., Ltd.)
An i-shot (Fluuchi Chemical Co .; purity 99.9%) was pulverized using a mortar, and the particle size of each of Mn and Bi was 1
Mn and B sieved to 00 mesh
i powder was prepared. Next, these Mn and Bi powders were converted to M
The mixture was weighed so that the molar ratio of n to Bi was 55:45, and was sufficiently mixed using a ball mill.

Next, these mixtures were molded into a 6 mmφ × 6 mm column using a pressure press at a pressure of 3 t / cm ² . Put this molded body in a sealed aluminum container,
After evacuation, nitrogen gas was introduced at 0.5 atm. Next, the container was placed in an electric furnace and heat-treated at a temperature of 265 ° C. for 3 days. After the heat treatment, it was taken out into the air, crushed lightly in a mortar, and its magnetic properties were measured. As magnetic properties, the maximum magnetic field is 1
The coercive force when a magnetic field of 6 kOe was applied and the amount of magnetization at 16 kOe were measured. Coercive force is 500-1000
In the range of Oe, the amount of magnetization was 53.4 emu / g.

(2) Pulverization of MnBi Ingot The obtained MnBi ingot is coarsely pulverized using a mortar in an inert (nitrogen) atmosphere using a glove box, and then finely pulverized using a ball mill. did. Regarding ball mill pulverization, a planetary ball mill was used to obtain MnBi1.
100 parts by weight of toluene was added to 0 parts by weight and pulverized. As a pulverizing method, a zirconia ball having a diameter of 1.0 mm was used.
rpm), the first stage of pulverization is performed under mild pulverization conditions, and the rotation speed (150 rpm) is further increased using a zirconia ball having a small ball diameter of 0.5 mm. A second stage of grinding was performed. MnBi obtained
The magnetic powder has an average particle size of 2.5 μm and a coercive force of 980.
0 Oe, the magnetization amount was 48.6 emu / g.

Thus, in ball mill pulverization,
When a non-polar solvent such as toluene is used as the solvent, the decrease in the amount of magnetization due to pulverization is small, and when the ball diameter is reduced as the pulverization proceeds, particles having a more uniform particle size distribution can be obtained. . As a result, high saturation magnetization was obtained despite the small particle size. This is because the generation of fine powder that causes a decrease in the amount of magnetization is small.

<< Stabilizing Treatment of MnBi Magnetic Powder >> According to the above-mentioned method, a MnBi magnetic powder having a desired shape and characteristics can be obtained. However, the MnBi magnetic powder in this state is unstable and corrosion due to the presence of moisture is caused. Then, the amount of magnetization decreases. Therefore, stabilization is performed by the heat treatment described below.

After ball milling, the MnBi magnetic powder was first taken out in a state of being immersed in toluene, transferred to a heat treatment vessel and vacuum-dried at room temperature (25 ° C.) for about 2 hours. Next, while being kept in the same container, first as a first stage heat treatment, 3
Heat treatment was performed at 0 ° C. for 24 hours. The heat treatment atmosphere is oxygen 1
Nitrogen gas containing 000 ppm was used. Further, as a second stage heat treatment, after the oxygen mixed gas filled in the container is evacuated and removed, about 0.3 torr of nitrogen gas is introduced so as not to exceed 1 torr during heating. And
Heat treatment was performed at 350 ° C. for 2 hours.

The magnetic powder subjected to the first and second heat treatments had a magnetization of 50.4 emu / g, a coercive force of 9,500 Oe, and a deterioration rate of the magnetization of 8%. In addition, the deterioration rate of the magnetization amount was measured by the following method.

<Degradation Rate of Magnetization Amount>
The glass was held in an atmosphere of 90 ° C. and a humidity of 90% in a glass dish for 7 days, and the deterioration rate of the saturation magnetization was determined from the change of the saturation magnetization after the holding to the saturation magnetization before the holding.

As described above, M which has been subjected to the heat treatment of the present invention
Even if the nBi magnetic powder is left for 7 days at a high temperature and humidity of 60 ° C. and a humidity of 90%, the deterioration rate of the saturation magnetization is 8%, and the deterioration rate without the stabilization treatment is 90%. It was found that the corrosion resistance was remarkably improved as compared with that of the above.

FIG. 4 shows, for reference, a magnetic card was prepared by using the MnBi magnetic powder obtained as described above in accordance with the method described later, and the magnetic flux density was changed according to the volume ratio of the magnetic powder. , The magnetic flux density of the magnetic card at 300K is in the range of 1200G to 1800G,
5 shows the result of examining the function of preventing the rewriting of the magnetic card in which the coercive force is changed. The rewrite prevention function was examined as follows. That is, after the magnetic card is demagnetized, the signal of 210 FCI is saturated-recorded (DC current 250 mA) at 300 K and reproduced, and the reproduced output is set as the initial value. Next, a DC current (500 mA) corresponding to a magnetic field of about 7000 Oe was applied to demagnetize the DC using the same magnetic head as that on which recording was performed, and thereafter, a signal output of 210 FCI was reproduced. As can be seen from FIG. 4, the rewriting prevention function has a close relationship with the coercive force at 300K, and it can be seen that the function is more exhibited when the coercive force is 5000 Oe or more.

<< Preparation of Magnetic Card Mixed with Multilayer and Magnetic Powder >> As described above, a magnetic recording medium using MnBi magnetic powder has a characteristic that once recorded, it cannot be easily rewritten at room temperature. When used in combination with another magnetic recording medium, a magnetic recording medium having novel features not found in conventional magnetic recording media can be obtained.

For example, when applied to a magnetic card, a magnetic layer using MnBi magnetic powder and a Co-γ-F
When formed at different positions on de surface, once de - - two kinds of magnetic layers of the magnetic layer using a conventional magnetic powder for magnetic recording, such as e ₂ O ₃ months fixed des which can not be rewritten and writing data - Data and data that can be freely rewritten by the user
A magnetic card having different kinds of data can be obtained.

The fixed data records the ID and password of the cardholder who must not be forged or tampered with, the card issuance location, the date of issuance, etc., and as rewritable data. For example, a usage method such as recording a card usage history each time it is used is conceivable.

Further, a magnetic layer using MnBi magnetic powder and a magnetic layer using another magnetic powder such as Co-γ-Fe ₂ O ₃ are laminated, or MnBi magnetic powder and Co
When other magnetic powders such as -γ-Fe ₂ O ₃ are mixed and used, two types of data, fixed data that cannot be rewritten and data that can be rewritten, can be multiplex-recorded on the same track. Will be possible.

In particular, when multiplex recording is performed in this manner, not only can data be recorded without reducing the print area of the magnetic card, but also it becomes extremely difficult to decode the written data. Thus, a magnetic card having extremely high security can be obtained.

A magnetic layer using MnBi magnetic powder and Co
-When two types of magnetic layers, such as magnetic layers using other magnetic powders such as γ-Fe ₂ O _3, are formed at different positions on the card surface, a MnBi magnetic coating and a magnetic recording medium This can be realized by forming magnetic layers at different positions using the magnetic paint used for the above.

Therefore, in this embodiment, MnBi magnetic powder
A magnetic layer using Co-γ-Fe _Two O_Three Other magnets such as
Magnetic layers using conductive powder at different positions on the card surface
The magnetic layer using MnBi magnetic powder and Co-γ
-Fe_Two O_Three Laminated magnetic layers using other magnetic powders
And MnBi magnetic powder and Co-γ-Fe _Two 
O_Three For example, when mixing other magnetic powders
I will explain it.

<< Laminated / Single Layer Mixed Card >> A magnetic layer using MnBi magnetic powder is formed in a stripe shape, and Co-γ-Fe ₂ O ₃ or barium ferrite magnetic powder or the like is covered so as to cover this magnetic layer. An example in which a magnetic layer using a normal magnetic powder used for a magnetic recording medium of the above type is formed on the entire surface of the card will be described.

Example 2 (1) Preparation of paint for magnetic layer which cannot be rewritten The paint for magnetic layer which cannot be rewritten is the MnBi magnetic powder obtained in Example 1 (average particle diameter 2.5 μm, coercive force 9
500 Oe, saturation magnetization of 50.4 emu / g) to give a coating for a magnetic layer having the following composition. MnBi magnetic powder 100 parts by weight MPR-TAO (manufactured by Nissin Chemical Co .; amine-modified vinyl chloride 25 ビ ニ ル -vinyl acetate copolymer) stearylamine 6 ア リ ル cyclohexanone 50〃toluene 50〃

(2) Preparation of rewritable paint for magnetic layer As a rewritable magnetic paint for normal magnetic recording,
Co-γ-Fe ₂ O ₃ magnetic powder having a coercive force of 640 Oe, a saturation magnetization of 74.5 emu / g, and an average particle length of 0.3 μm was used.

Co-γ-Fe ₂ O ₃ magnetic powder 80 parts by weight Vinyl chloride-vinyl acetate copolymer (UCC; VAGH) 10〃 Polyurethane resin (T-5250, manufactured by Dainippon Ink and Chemicals, Inc.) 6〃 Cyclohexanone 75 {Toluene 75} This composition was sufficiently kneaded and dispersed by a sand grinder mill, and then 5 parts by weight of a polyfunctional polyisocyanate compound (manufactured by Nippon Polyurethane Industry Co., Ltd .; Colonate L) was added. And

(3) Preparation of Magnetic Layer First, a magnetic paint using MnBi magnetic powder was applied to a thickness of 190 μm.
It was applied on a PET base film of μm in a stripe shape while applying a longitudinal orientation magnetic field of 1500 Oe so that the thickness after drying was 5 μm. This stripe was 5 mm in width, and was formed such that when formed into a magnetic card, the stripe was parallel to the long side of the magnetic card. Continue C
A longitudinal orientation magnetic field of 1500 Oe was applied to the coating using the o-γ-Fe ₂ O ₃ magnetic powder over the entire surface of the PET base film so as to cover the stripes so that the thickness after drying was 10 μm. While applying.

(4) Preparation of Magnetic Card The above-mentioned PET base film on which two types of magnetic layers were formed was punched into a card shape to obtain a magnetic card.

(5) Initialization and Recording / Reproduction Initialization was performed by cooling the magnetic card by immersing it in liquid nitrogen, and then immediately applying an AC magnetic field of 1000 Oe to initialize. The signal was recorded by the following method.

A magnetic layer using MnBi magnetic powder and a magnetic layer using Co-γ-Fe ₂ O ₃ magnetic powder using a magnetic card reader / writer (manufactured by Sanwa Newtech; CRS-700). In the portion where is stacked, first, as fixed data that cannot be rewritten, (0,
A sequence of numbers (1, 2, 3, 4,) was recorded. Next, as a rewritable signal, a recording current of 100 mA was applied to a portion where only a magnetic layer using Co-γ-Fe ₂ O ₃ magnetic powder was formed using the same magnetic card reader / writer.
The digit string (5, 6, 7, 8, 9) was recorded.

Next, the recorded data was reproduced using the same magnetic card reader / writer as used for recording. As a result, the same sequence of numbers (0, 1, 2, 3, 4,) as in the recording was reproduced from the laminated portion. From the portion where only the magnetic layer using Co-γ-Fe ₂ O ₃ magnetic powder is formed,
The number string of (5, 6, 7, 8, 9) could be reproduced. Next, assuming tampering, the recording current is 100 mA, and the number sequence of (5, 6, 7, 8, 9) is indicated by Co-γ-Fe ₂ in the laminated portion.
A numerical string of (0, 1, 2, 3, 4,) was overwritten in a portion where only the magnetic layer using the O ₃ magnetic powder was formed.

As a result of the reproduction using the same card reader / writer again, (0, 1, 2, 2) was obtained from the portion where only the magnetic layer using the Co-γ-Fe ₂ O ₃ magnetic powder was formed.
The data of (3) and (4) were reproduced, and it was confirmed that the data was correctly rewritten.

On the other hand, a reading error occurs in the laminated portion,
Data could not be reproduced. This is because the data once written in the magnetic layer using the MnBi magnetic powder cannot be rewritten, so that the data (0,1,2,3,4) written first in the magnetic layer using the MnBi magnetic powder can be used. Data and C
The magnetic layer using o-γ-Fe ₂ O ₃ magnetic powder has an overcoat.
This is because (5, 6, 7, 8, 9) of the written data are mixed, resulting in a reading error.

The magnetic layer using the MnBi magnetic powder and another magnetic powder such as Co-γ-Fe ₂ O ₃ (Mn
2 of magnetic layer using magnetic powder other than Bi magnetic powder)
By forming different types of magnetic layers at different positions on the card surface, there are two types: fixed data that cannot be rewritten once data has been written, and data that can be freely rewritten by the user.
A card having various kinds of data can be obtained. That is, the magnetic card processing system and the reading device of the present invention provide a MnBi magnetic powder that combines the characteristics of a normal magnetic recording medium that facilitates recording and reproduction with the characteristics of preventing accidents and unauthorized use. A magnetic card processing system and a reading device using another magnetic powder can be provided.

Example 3 In Example 2, a coercive force of 2800 Oe and a saturation magnetization of 64.5 emu / were used in place of the Co-γ-Fe ₂ O ₃ magnetic paint.
g, a magnetic card was produced in the same manner as in Example 2 except that barium ferrite magnetic powder having an average particle length of 0.6 μm was used. With respect to this card, the same data as in Example 2 was recorded and reproduced except that the recording current was set to 200 mA. As a result, as in Example 2, the portion where the magnetic layer using the MnBi magnetic powder and the magnetic layer using the barium ferrite magnetic powder were stacked resulted in a read error, and only the magnetic layer using the barium ferrite magnetic powder was read. It was confirmed that the formed portion was correctly rewritten.

<< Use of Mixed Magnetic Powder and Magnetic Layer-Laminated Magnetic Card >> MnBi magnetic powder, gamma iron oxide magnetic powder,
Co-containing iron oxide magnetic powder, Ba-ferrite magnetic powder,
By mixing and using other magnetic powders having a coercive force of 250 to 3000 Oe at room temperature, such as Sr-ferrite magnetic powder or Fe-based metal magnetic powder,
Alternatively, MnBi can be obtained by laminating a magnetic layer using MnBi magnetic powder and a magnetic layer using the above magnetic powder.
As in the case of the magnetic layer using only the i-magnetic powder, it is possible to exhibit the characteristic that data falsification is difficult. That is, MnB
Even if the magnetic powder other than i or the data of the magnetic layer using the magnetic powder is rewritten, the data of the MnBi magnetic powder or the magnetic layer using the MnBi magnetic powder is not rewritten. Types of signals are mixed and cannot be read by a normal reader.

The advantage of the magnetic recording medium having such a structure is that, as described above, since the above magnetic powder generally has a larger saturation magnetization than the MnBi magnetic powder, only the MnBi magnetic powder was used. As compared with the case, the magnetic flux density of the magnetic recording medium is increased, and high output is easily obtained. When an oxide-based magnetic powder is used in combination, these magnetic powders have no problem of corrosion, so that the corrosion resistance of the magnetic recording medium is further improved. By using the MnBi magnetic powder in combination with another low coercivity magnetic powder, it is possible to reduce the data write current value while maintaining the feature that data falsification is difficult. Multiple data can be recorded by overwriting different data on the same track during data recording and separating and reproducing the data through a filter or the like during reproduction. 4 points.

Among these advantages, the advantage of is MnB
The characteristics are basically the same as those of the magnetic recording medium using the i-magnetic powder. However, the advantage of Mn
Mixing and using Bi magnetic powder and other magnetic powder,
Alternatively, it can be realized only by laminating magnetic recording media using these magnetic powders, and multiplex recording of two types of data, fixed data that cannot be rewritten and data that can be rewritten, on the same track. It is possible to do. Magnetic recording media to realize the advantages there,
And its recording / reproducing characteristics will be described.

Example 4 (Preparation of Laminated Magnetic Card) Fixed data which cannot be rewritten by laminating a magnetic recording medium using MnBi magnetic powder and a magnetic recording medium using another magnetic powder.
An example of a magnetic card capable of multiplex-recording two types of data, that is, data and rewritable data, on the same track will be described.

(1) Preparation of Non-rewritable Magnetic Layer Paint The paint using the MnBi magnetic powder shown in Example 2 was used as the magnetic paint for the non-rewritable magnetic layer.

(2) Preparation of rewritable paint for magnetic layer As a typical rewritable magnetic paint for magnetic recording,
Co-γ-Fe ₂ O ₃ magnetic powder having a coercive force of 640 Oe, a saturation magnetization of 74.5 emu / g, and an average particle length of 0.3 μm was used.

Co-γ-Fe ₂ O ₃ magnetic powder 80 parts by weight Vinyl chloride-vinyl acetate copolymer (VACH, manufactured by UCC) 10 樹脂 Polyurethane resin (T-5250, manufactured by Dainippon Ink and Chemicals, Inc.) 6〃 Cyclohexanone 75 {Toluene 75} This composition was sufficiently kneaded and dispersed by a sand grinder mill, and then 5 parts by weight of a polyfunctional polyisocyanate compound (manufactured by Nippon Polyurethane Industry Co., Ltd .; Colonate L) was added. And

(3) Preparation of Magnetic Layer First, a magnetic paint for the upper layer using Co-γ-Fe ₂ O ₃ magnetic powder was applied on a 30 μm-thick PET base film on which a release layer was formed, after drying. The coating was performed while applying a longitudinal orientation magnetic field of 15000e so that the thickness became 10 μm.
Subsequently, a paint using MnBi magnetic powder was coated on the surface of this coating film so as to have a thickness of 1500 μm after drying so as to have a thickness of 10 μm.
e was applied while applying a longitudinal orientation magnetic field.

(4) Preparation of Magnetic Card After the magnetic layer was slit into a magnetic tape, it was embedded in a PVC substrate by heating and pressing to form a magnetic card. That is, the magnetic layer of the magnetic tape slit to a width of 6 mm was superposed on a vinyl chloride substrate for a magnetic card having a thickness of 0.76 mm, and pressed with a heating roller from above to adhere to the vinyl chloride substrate. After this bonding, the PET film is peeled off,
The magnetic layer was embedded in a vinyl chloride substrate by heating and pressing with a press plate, and then punched into a card size to produce a magnetic card.

(5) Initialization and Recording / Reproduction Initialization was performed by the same method as described above. The signal was recorded by the following method. First, using a magnetic card writer (manufactured by Sanwa Newtech Co., Ltd .; CRS-700), a sine wave having a recording current of 200 mA and a bit length of 400 μm is recorded as fixed data that cannot be rewritten. did. This signal was designated as (A) signal. Next, as a rewritable signal, a sine wave of 100 μm in terms of bit length was recorded at a recording current of 100 mA using the same magnetic card reader / writer.

For reproducing signals, a reproduced signal voltage was obtained by using the same magnetic card reader / writer as used for recording. In order to separate the upper and lower signals, the output from the magnetic head was taken into an oscilloscope via a band-pass filter, and the reproduced output was obtained from the amplitude of the reproduced waveform. As the bandpass filter, the frequencies of the low-pass filter and the high-pass filter were set so as to pass + 100% and -50% of the frequency around the frequency to be measured.

Example 5 In Example 4, the magnetic powder used for the rewritable magnetic layer was changed from Co-γ-Fe ₂ O ₃ magnetic powder to coercive force 2
800 Oe, saturation magnetization 64.5 emu / g, average particle length
In the same manner as in Example 4 except that the barium ferrite magnetic powder of 0.6 μm was used, a magnetic card having a magnetic layer composed of an upper layer composed of barium ferrite magnetic powder and a magnetic layer composed of a lower layer composed of MnBi magnetic powder was used. It was manufactured and signals were recorded and reproduced by the same method as in Example 4.

Example 6 In Example 4, the magnetic powder used for the rewritable magnetic layer was changed from Co-γ-Fe ₂ O ₃ magnetic powder to coercive force 3
00Oe, saturation magnetization 74.3 emu / g, average grain length 0.
Except for changing the magnetic powder γ-Fe ₂ O ₃ of 5 [mu] m, in the same manner as in Example 4, magnetic layer upper is made of γ-Fe ₂ O ₃ magnetic powder, the lower layer of the magnetic layer consisting of MnBi magnetic powder A magnetic card having the above configuration was manufactured, and signals were recorded and reproduced in the same manner as in Example 4.

Example 7 (Preparation of Magnetic Card Using Mixed Powder) By mixing and using MnBi magnetic powder and other magnetic powder, two types of fixed data that cannot be rewritten and data that can be rewritten are used. An example of a card capable of multiplex-recording the above data on the same track will be described.

In Example 4, in the composition of the magnetic coating material for the rewritable magnetic layer, the magnetic powder was changed to Co-γ-F
A magnetic paint was prepared using a magnetic powder in which Co-γ-Fe ₂ O ₃ magnetic powder and MnBi magnetic powder were mixed in a weight ratio of 7: 3 instead of e ₂ O ₃ magnetic powder. This magnetic paint was placed on a 30 μm-thick PET base film on which a release layer was formed, so that the thickness after drying was 20 μm.
The coating was performed while applying a longitudinal orientation magnetic field of 500 Oe. Thereafter, the magnetic layer was slit into a magnetic tape in the same manner as in Example 4, and then embedded in a PVC substrate by heating and pressing to form a magnetic card. Recording and reproduction of signals were performed in the same manner as in Example 4.

Example 8 In Example 7, Co-γ-Fe ₂ O ₃ magnetic powder and M
The mixing ratio of the nBi magnetic powder is 7: 3 to 5: 5 by weight.
A magnetic coating material was prepared in the same manner as in Example 7, except that the magnetic recording medium was prepared, and a magnetic card was prepared for recording and reproducing signals.

Example 9 In Example 7, the magnetic powder to be mixed was Co-γ-Fe
Γ-Fe ₂ O ₃ from ₂ O ₃ magnetic powder and MnBi magnetic powder
A magnetic paint was prepared in the same manner as in Example 7 except that the magnetic powder and the MnBi magnetic powder were changed to a mixing ratio of 7: 3 by weight, and a magnetic card was prepared to record and reproduce signals. Was done.

Comparative Example 1 Using only the magnetic paint using the Co-γ-Fe ₂ O ₃ magnetic powder described in Example 4, this magnetic paint was coated on a 30 μm thick PET base film having a release layer formed thereon. 1500 Oe so that the thickness after drying becomes 20 μm.
Was applied while applying a longitudinal orientation magnetic field to produce a magnetic card, and recording and reproduction of signals were performed.

Comparative Example 2 Using only the magnetic paint using the barium ferrite magnetic powder described in Example 5, this magnetic paint was applied to a 30 μm-thick PET base film on which a release layer was formed.
Coating was performed while applying a longitudinal orientation magnetic field of 3000 Oe so that the thickness after drying became 20 μm, and a magnetic card was prepared to record and reproduce signals.

Table 1 shows the results of examining the reproduction output of the magnetic cards obtained in Examples 4 to 9 and Comparative Examples 1 and 2.
At the same time, in order to examine the stability of the recording data, the results of examining the change in the reproduction output by applying a DC magnetic field of 4000 Oe after recording the signal are also shown.

[0125]

As is clear from Table 1, in the magnetic cards of Examples 4 to 6 in which a magnetic layer using MnBi magnetic powder and a magnetic layer using another magnetic powder were laminated, the fixed signal (A) It can be seen that even when the rewritable signal (B) is overwritten, both the fixed signal (A) and the rewritable signal (B) can be separated and reproduced with high output. In other words, the magnetic card processing system and the reading apparatus of the present invention combine the characteristics of a normal magnetic recording medium, which facilitates recording and reproduction, with the characteristics of preventing accidents and unauthorized use.
It is possible to provide a magnetic card processing system and reader using a magnetic powder and another magnetic powder. In addition, according to the magnetic card processing method of the present invention, the authenticity can be determined. Further, in Examples 4 to 6 above, the magnetic layers were laminated, but similar results were obtained with the mixed systems of Examples 7 to 9.

That is, a card using a mixture of MnBi magnetic powder and another magnetic powder as the magnetic powder (Example 7)
9), both the fixed signal (A) and the rewritable signal (B) can be separated and reproduced with high output. On the other hand, in the card using only the Co-γ-Fe ₂ O ₃ magnetic powder and the barium ferrite magnetic powder (Comparative Examples 1 and 2), when the signal (B) is overwritten, (A)
The signal has been erased and cannot be reproduced.

Regarding the magnetic field stability, the cards using the MnBi magnetic powder (Examples 4 to 9) were all 400
Even after the application of a magnetic field of 0 Oe, the initially recorded signal (A) remains without being erased, indicating that it functions as fixed data. On the other hand, Co-γ-F
In a card using only e ₂ O ₃ magnetic powder and barium ferrite magnetic powder (Comparative Examples 1 and 2), 4000 Oe
It can be seen that when the magnetic field is applied, not only the initially recorded signal (A) but also the subsequently recorded signal (B) are erased to a level at which reproduction is impossible. That is, in the state where the fixed signal (A) and the rewritable signal (B) are overwritten, the authenticity can be determined by applying an erasing magnetic field (application of a 4000 Oe magnetic field). For example, in Examples 4 to 9, since the fixed signal (A) remains even after the application of the erasing magnetic field, it is determined that the signal is genuine.

Further, when a mixed magnetic powder of MnBi magnetic powder and another magnetic powder is used, Examples 7 and 8 were used.
As can be seen from the comparison, when the mixing ratio of the MnBi magnetic powder is increased, the output ratio of the fixed signal (A) recorded earlier becomes larger than the output of the rewritable signal (B).

In this embodiment, the magnetic layer using MnBi magnetic powder was also used as the magnetic recording medium having the magnetic layers laminated thereon.
An example was described in which the thickness of each of the magnetic layers using magnetic powders other than the Bi magnetic powder was 10 μm. But,
It is of course possible to arbitrarily change the output ratio of the fixed signal (A) and the rewritable signal (B) by changing the thickness of both magnetic layers.

In this embodiment, the basic structure in the case of laminating the magnetic layers and the case of using the mixed magnetic powder is described. The front surface and the back surface of the magnetic layer and the space between the magnetic layers to be further laminated are described. It is of course possible to form other magnetic layers, water-repellent layers, and the like according to the purpose.

As described above, the magnetic layer containing the MnBi magnetic powder and the magnetic layer using a magnetic powder other than the MnBi magnetic powder may be laminated, or the MnBi magnetic powder and the MnBi magnetic powder may be laminated.
When a magnetic layer is formed by forming a magnetic layer containing a mixed magnetic powder with other magnetic powders other than the magnetic powder, there are various forms, such as a stripe form as described above. − May be provided on the entire surface.

Also, as shown in FIG. 5, a magnetic layer 2 containing MnBi magnetic powder in a stripe shape is embedded on a card substrate 1, and the magnetic layer 2 containing the MnBi magnetic powder is embedded on the card substrate 1. A magnetic layer 3 using a magnetic powder other than the MnBi magnetic powder may be laminated. Further, as shown in FIG. 6, a magnetic layer 2 containing a striped MnBi magnetic powder is formed on a card substrate 1. M is formed so as to cover the magnetic layer 2.
The magnetic layer 3 using a magnetic powder other than the nBi magnetic powder may be formed on the card substrate 1.

As shown in FIG. 7, MnBi is formed on the magnetic layer 2 containing the MnBi magnetic powder such that the magnetic layer 2 containing the MnBi magnetic powder in a stripe shape is sandwiched on the card substrate 1.
The magnetic layer 3 using a magnetic powder other than the magnetic powder may be formed.

[0135] Further, as shown in FIG.
A magnetic layer 2 containing stripe-shaped MnBi magnetic powder is buried on the surface of the substrate, and a stripe-shaped magnetic layer 3 using other magnetic powder than MnBi magnetic powder is formed on the back surface of the card substrate 1.
May be buried, and as shown in FIG.
A magnetic layer 2 containing a striped MnBi magnetic powder and a striped magnetic layer 3 using a magnetic powder other than the MnBi magnetic powder may be buried and formed on the surface of the substrate 1.

Further, as shown in FIG. 10, a magnetic layer 2 containing MnBi magnetic powder is formed on the entire front surface of the card substrate 1, and other magnetic layers other than the MnBi magnetic powder are formed on the entire back surface of the card substrate 1. The magnetic layer 3 using powder may be formed. As shown in FIG. 11, a magnetic layer 2 containing MnBi magnetic powder is formed on the entire front and back surfaces of the card substrate 1, and these magnetic layers 2 are formed. A magnetic layer 3 using a magnetic powder other than the MnBi magnetic powder may be further formed thereon.

<< Magnetic Recording Medium Reproducing Apparatus >> As described above, a magnetic recording medium (for example, a magnetic card) using MnBi magnetic powder can be easily erased at room temperature once data is recorded. It is characterized by the fact that recorded data cannot be falsified easily. On the other hand, data reading does not require a special device, and one of the major features is that a normal card reader can be used. The feature that the data written on the card is difficult to falsify is combined with advanced printing technology to prevent the forgery of the card itself, thereby providing strong security. Demonstrate.

On the other hand, data recorded on this magnetic card is read by a general-purpose reader in the same manner as a normal magnetic card.
The feature which can be read by using this allows the data of this magnetic card to be copied to another conventional magnetic card.
In applications where the card is used without the human eye,
Even if it is a forged card, if the recorded data is correct data, the data is read as an intrinsic card.

Therefore, a reproducing method and a reproducing apparatus which can prevent reproduction by such a copy card and can reproduce data only with a genuine magnetic card using MnBi magnetic powder will be described. .

Embodiment 10 FIG. 12 shows a reproducing apparatus. This reproducing apparatus 10 is provided with a reproducing head 13 for reading out data recorded on a magnetic card 12 inserted from a card insertion port 11, and the reproducing head 13 and the card insertion are provided. 5 between mouths 11
The permanent magnet 14 having a magnetic field strength of 00 to 5000 Oe is provided.

The reproducing apparatus 10 shown in FIG. 13 has a magnetic head 15 for applying an AC magnetic field instead of the permanent magnet 14 of the apparatus shown in FIG. Before reproducing by the reproducing head 13, a magnetic field can be applied to the card by the magnetic head.

In the reproducing apparatus shown in FIG. 14, a DC bias power supply 16 is connected to the reproducing head 13 of the apparatus shown in FIG. 12, and the reproducing head 13 applies a DC bias magnetic field to reproduce data. Has become.

When the reproducing method and the reproducing apparatus of this embodiment are used, there is a possibility that not only the magnetic card intended for unauthorized use but also the data of the ordinary magnetic card may be erased by mistake. However, such a trouble is caused by the fact that a normal magnetic card cannot be inserted, or that the shape of the card is devised so that the magnetic card is ejected before applying a magnetic field, or that the magnetic data cannot be inserted.
This can be prevented by adding identification information other than data.

FIG. 15 shows an example in which a notch 17 or a small hole is provided in a part of the magnetic card 12 to make it different in shape from a normal magnetic card. When inserted into the reproducing apparatus, the notch 17 or the pore is detected, for example, optically or mechanically, and the magnetic card having the notch 17 or the pore is permitted to be inserted, and the notch 17 or the pore is detected. Cards without pores are immediately discharged from the regenerator.

FIG. 16 shows an example in which an identification mark 18 is provided by printing on the surface of the magnetic card 12 with, for example, an ink containing an infrared or ultraviolet excitation type phosphor. Since 18 is almost transparent, the appearance of the magnetic card 12 is not impaired. When this magnetic card is inserted into the reproducing apparatus, the identification mark 18 is irradiated with infrared rays or ultraviolet rays to excite the fluorescent material, and the fluorescence emitted from the identification mark 18 is detected, whereby the identification mark is detected. The magnetic card 12 with the mark 18 is distinguished from the magnetic card 12 which is not.

Next, a description will be given of the result of recording and reproduction of a magnetic card using the present apparatus. For measurement, M
A magnetic card using nBi magnetic powder or another magnetic powder was applied. That is, the magnetic car of Reference Example 1
The magnetic card using MnBi magnetic powder was used as the magnetic card, and the magnetic cards of Comparative Examples 1 and 2 were made of Co-γ- magnetic powder used in the above-described ordinary magnetic recording medium.
This is a magnetic card using Fe ₂ O ₃ and barium ferrite magnetic powder.

First, a card using MnBi magnetic powder was initialized and data was recorded. The initialization was performed by immersing the card in liquid nitrogen for cooling as described above, and then immediately applying an alternating magnetic field of 1000 Oe. Next, using a magnetic card writer, a rectangular wave was recorded at a recording current of 200 mA and a recording density of 210 FCI. The cards using Co-γ-Fe ₂ O ₃ and barium ferrite magnetic powder of Comparative Examples 1 and ₂ are as follows.
Data was recorded in the same manner except that the initialization step was omitted.

Regarding data reproduction, first, an initial reproduction output was obtained by using a reader / writer used for recording a signal. This reader / writer has a gap length of 2 as a magnetic head.
A 0 micron MnZn ferrite head is used.

Next, the reproducing apparatus (A) having the configuration shown in FIG.
Was used to measure the reproduction output of each card. The magnetic field at the card surface by the permanent magnet 14 of this device is about 2500
Oe. The value of the playback output measured by this playback device is
The value was obtained as a relative value to the value of the initial reproduction output measured using the reader / writer. The value of the reproduced output was determined from the amplitude of the reproduced waveform observed with an oscilloscope.

Next, the same measurement was carried out using a reproducing apparatus (B) having a ring-type magnetic head having a gap length of 40 μm, instead of the permanent magnet 14 shown in FIG. This head has a frequency of 1 kHz and a recording current of 1
A magnetic field was applied by passing a current of 00 mA. The value of the magnetic field at this time was about 2000 Oe at the position of the magnetic layer. Table 2 shows the measurement results of the reproduction output using these two types of devices.

[0151]

As is apparent from Table 2, when a magnetic field smaller than the coercive force of the magnetic card using the MnBi magnetic powder is applied to the magnetic layer before reproducing the signal with the magnetic head,
It can be seen that the reproduction output of the magnetic card using Bi magnetic powder hardly changes, whereas the reproduction output of the card using the magnetic powder for normal magnetic recording is extremely low.

This means that the data recorded on the genuine magnetic card using the MnBi magnetic powder is copied to the magnetic card using the normal magnetic powder.
It can be seen that the data has been erased or destroyed and cannot be read. Therefore, only data of a genuine magnetic card using MnBi magnetic powder cannot be reproduced,
It can be seen that irregular use due to the copy card can be prevented.

[0154]

As described above, according to the present invention, recording for recording a magnetic signal on a magnetic card having at least one magnetic layer containing a MnBi magnetic powder and another magnetic powder on a substrate is provided. A magnetic card processing system comprising a device and a reading device for reproducing a recorded magnetic signal, wherein the recording device is a demagnetized Mn.
Recording means for recording a non-rewritable fixed signal on the Bi magnetic powder, and recording means for recording a rewritable signal on a magnetic powder other than the MnBi magnetic powder; And a reproducing means for reproducing both the fixed signal recorded on the recording medium and the rewritable signal recorded on magnetic powder other than the MnBi magnetic powder. According to the present invention, there is provided a magnetic card reader, wherein the reproducing means reproduces a non-rewritable fixed signal recorded on the MnBi magnetic powder, and the reproducing means reproduces a fixed signal recorded on the MnBi magnetic powder. And reproducing means for reproducing a rewritable signal that is provided by applying a magnetic card reader, Unauthorized use of the gas card can be prevented.

Further, in the present invention, Mn is formed on the substrate.
A method for processing a magnetic card provided with at least one magnetic layer containing a Bi magnetic powder and another magnetic powder, wherein a fixed signal that cannot be rewritten is recorded in the MnBi magnetic powder, A rewritable signal is recorded on the other magnetic powder, and the authenticity of the magnetic card is determined based on the fixed signal, and an area where a rewritable signal is recorded after the determination of the authenticity is recorded.
By applying a magnetic card processing method characterized in that another signal different from the rewritable signal is newly recorded, unauthorized use of the magnetic card can be prevented, and There is also an effect that updating can be performed.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of the temperature dependence of the coercive force of a MnBi magnetic powder.

FIG. 2 is a diagram showing an example of an initial magnetization curve and a hysteresis curve of a magnetic recording medium using MnBi magnetic powder.

FIG. 3 MnBi magnetic powder and Co-γ-Fe ₂ O ₃
FIG. 4 is a diagram showing the magnetic field stability of the reproduction output of a magnetic card using magnetic powder.

FIG. 4 is a diagram showing a relationship between a coercive force of a magnetic recording medium using MnBi magnetic powder and a falsification preventing function.

FIG. 5 is an enlarged sectional view showing an example of a magnetic card obtained by the present invention.

FIG. 6 is an enlarged sectional view showing another example of the magnetic card obtained by the present invention.

FIG. 7 is an enlarged sectional view showing another example of the magnetic card obtained by the present invention.

FIG. 8 is an enlarged sectional view showing another example of the magnetic card obtained by the present invention.

FIG. 9 is an enlarged sectional view showing another example of the magnetic card obtained by the present invention.

FIG. 10 is an enlarged sectional view showing another example of the magnetic card obtained by the present invention.

FIG. 11 is an enlarged sectional view showing another example of the magnetic card obtained by the present invention.

FIG. 12 is a schematic configuration diagram of a playback device according to an embodiment of the present invention.

FIG. 13 is a schematic configuration diagram of a playback device according to another embodiment of the present invention.

FIG. 14 is a schematic configuration diagram of a playback device according to still another embodiment of the present invention.

FIG. 15 is a plan view of a card-shaped magnetic recording medium according to an embodiment of the present invention.

FIG. 16 is a plan view of a card-shaped magnetic recording medium according to another embodiment of the present invention.

[Description of Signs] 1 Card substrate 2, 3 Magnetic layer 10 Reproducing device 12 Magnetic card 13 Reproducing head 14 Permanent magnet 15 Magnetic head 16 Bias power supply 17 Notch 18 Identification mark

 ──────────────────────────────────────────────────続 き Continuation of the front page (31) Priority claim number Japanese Patent Application No. 6-192902 (32) Priority date July 25, 1994 (July 25, 1994) (33) Priority claim country Japan (JP) (31) Priority claim number Japanese Patent Application No. 6-222418 (32) Priority date August 24, 1994 (Aug. 24, 1994) (33) Priority claim country Japan (JP) (31) Priority claim number Japanese Patent Application No. 6-247117 (32) Priority date September 14, 1994 (September 14, 1994) (33) Priority claiming country Japan (JP) (31) Priority claim number Japanese Patent Application No. Hei 6-247118 ( 32) Priority Date September 14, 1994 (September 14, 1994) (33) Priority Country Japan (JP) (72) Inventor Shinichi Kitahata 1-1-88 Ushitora, Ibaraki City, Osaka Hitachi Maxell Inside (72) Inventor Toshinobu Sueyoshi 1-88 Ushitora, Ibaraki-shi, Osaka Inside Hitachi Maxell Co., Ltd. (72) Inventor Noriaki Otani 1-88 Ushitora, Ibaraki-shi, Osaka Hitachi Maxell Co., Ltd. (72) Inventor Hirofumi Tagawa 1-88 Ushitora, Ibaraki-shi, Osaka Pref.

Claims (15)

[Claims] 1. A recording device for recording a magnetic signal on a magnetic card provided with at least one magnetic layer containing a MnBi magnetic powder and another magnetic powder on a substrate, and reproducing the recorded magnetic signal. What is claimed is: 1. A magnetic card processing system comprising: a reading device, wherein the recording device records a non-rewritable fixed signal on a demagnetized MnBi magnetic powder; and a magnetic powder other than the MnBi magnetic powder. Recording means for recording a rewritable signal on the MnBi magnetic powder and the rewritable signal recorded on another magnetic powder other than the MnBi magnetic powder. A magnetic card processing system comprising a reproducing unit for reproducing both of the signals. 2. The magnetic card processing system according to claim 1, wherein the magnetic layer has a structure in which a magnetic layer containing only MnBi magnetic powder and a magnetic layer containing other magnetic powder than MnBi magnetic powder are laminated. . 3. A magnetic layer comprising a magnetic layer containing both MnBi magnetic powder and another magnetic powder.
A magnetic card processing system according to claim 1. 4. The magnetic card processing system according to claim 1, wherein the non-rewritable fixed signal and the rewritable signal are recorded on the same or different tracks. 5. The magnetic card processing system according to claim 1, wherein the recording density of the rewritable signal is 3 to 100 times the recording density of the non-rewritable fixed signal. 6. A magnetic card reader comprising a substrate provided with at least one magnetic layer containing a MnBi magnetic powder and another magnetic powder, the rewritable information recorded on the MnBi magnetic powder. A reading device for a magnetic card, comprising: reproducing means for reproducing a fixed signal; and reproducing means for reproducing a rewritable signal recorded on a magnetic powder other than the MnBi magnetic powder. 7. The magnetic card reader according to claim 6, wherein the magnetic layer has a configuration in which a magnetic layer containing only MnBi magnetic powder and a magnetic layer containing other magnetic powder than MnBi magnetic powder are laminated. . 8. The magnetic layer comprises a magnetic layer containing both MnBi magnetic powder and another magnetic powder.
The magnetic card reader according to claim 1. 9. The magnetic card reader according to claim 6, wherein the non-rewritable fixed signal and the rewritable signal are recorded on the same or different tracks. 10. The magnetic card reader according to claim 6, wherein the recording density of the rewritable signal is 3 to 100 times the recording density of the non-rewritable fixed signal. 11. A method for processing a magnetic card having a substrate provided with at least one magnetic layer containing MnBi magnetic powder and another magnetic powder on a substrate, wherein the MnBi magnetic powder has a fixed signal which cannot be rewritten. A rewritable signal is recorded on the magnetic powder other than the MnBi magnetic powder, and the authenticity of the magnetic card is determined based on the fixed signal. A new signal different from the rewritable signal is newly recorded in an area where is recorded. 12. The magnetic card processing method according to claim 11, wherein the magnetic layer has a configuration in which a magnetic layer containing only MnBi magnetic powder and a magnetic layer containing other magnetic powder other than MnBi magnetic powder are laminated. . 13. The magnetic card processing method according to claim 11, wherein the magnetic layer comprises a magnetic layer containing both MnBi magnetic powder and another magnetic powder. 14. The magnetic card processing method according to claim 11, wherein the non-rewritable fixed signal and the rewritable signal are recorded on the same or different tracks. 15. The magnetic card processing method according to claim 11, wherein the recording density of the rewritable signal is 3 to 100 times the recording density of the non-rewritable fixed signal.