JP2713370B2 - Reading method of magnetic recording medium - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording medium, and more particularly to a card type magnetic recording medium having an identification pattern indicating a code for authenticity identification.

[0002]

2. Description of the Related Art A magnetic recording medium is provided with an identification pattern indicating a code for identifying that the medium is a legitimate magnetic recording medium. In a conventional magnetic recording medium, this identification pattern includes a predetermined arrangement of one or more magnetic layers formed using magnetic ink and one or more nonmagnetic layers formed using non-magnetic ink. They may be formed in combination. This is to prevent the identification code from being decrypted by a third party and being used illegally, thereby ensuring the safety of the magnetic recording medium. The magnetic materials to be mixed in the magnetic ink for forming the magnetic layer include magnetite (Fe ₃ O ₄ ) powder and maghemite (γ-Fe ₂ O ₃ ).
Powder, iron powder and the like are generally used.

[0003]

However, in the case of a conventional identification pattern containing a magnetic material as described above, when a magnetic recording medium is scanned by a reading magnetic head in order to identify the authenticity of the magnetic recording medium, In some cases, an accurate output signal cannot be obtained, and the accuracy of the authenticity determination is not sufficient.

An object of the present invention is to provide a magnetic recording medium having an identification pattern that can obtain an accurate and reproducible output signal when authenticating a magnetic recording medium.

[0005]

A magnetic recording medium according to the present invention has a magnetic recording layer provided on one surface of a substrate and a magnetic layer for authenticity identification provided in a predetermined pattern on the magnetic recording layer. Wherein the magnetic layer is made of a high magnetic permeability material that is magnetically saturated in a magnetic field formed by the read magnetic head.

In the present invention, as the magnetic material constituting the magnetic layer for authenticity discrimination, a high magnetic permeability material having a significantly higher magnetic permeability than a magnetic material conventionally used for the same purpose is used. . A magnetic layer made of a magnetic ink containing such a high magnetic permeability material is formed in front of a magnetic gap of the magnetic head when the magnetic layer is scanned by a reading magnetic head to identify the magnetic recording medium. The magnetic head is magnetically saturated by the strength of the magnetic field, and therefore always provides a stable output signal without being affected by external factors such as the contact state of the magnetic head.

The principle of the present invention will be described with reference to FIG. FIG. 1 shows MH curves in the first quadrant of two magnetic permeability materials having mutually different magnetic permeability, wherein curve I is for a high magnetic permeability material and curve II is for a low magnetic permeability material. As can be seen, the magnetic field applied is increased, the low permeability material, connection only the magnetization increases, while in high-permeability material, while the magnetic field H is small magnetization is proportionally increased But
When the magnetic field reaches a certain value, it saturates and does not increase any further. Namely the curve II showing the characteristics of a low permeability material, as the applied magnetic field is increased, the value of magnetization, M
1, M2, M3, and M4. However, as for the curve I showing the characteristics of the high magnetic permeability material, the value of the magnetization reaches M4 when the applied magnetic field increases to H1, and the value of the magnetization is almost constant even when the applied magnetic field further increases. At this time, the magnetization of the low magnetic permeability material is M1 lower than M4. When a magnetic recording medium is scanned by a reading magnetic head for identification, the magnetic flux density generated by the magnetic material due to the magnetic field applied by the magnetic head is substantially proportional to the output voltage output from the magnetic head. It is known that there is. Therefore, under the condition that a magnetic field of value H1 or more is applied by the magnetic head, the output signal voltage of the magnetic head is always constant, and the identification signal corresponding to the magnetic printing pattern given in advance can be obtained stably. become.

In the present invention, the term "high-permeability material" refers to a material which can be easily magnetically saturated by a magnetic field applied under a normal use condition in a current magnetic recording medium reader, generally a magnetic field of about 3 kOe. Means In particular,
Sendust (Fe-Al-Si), Permalloy (Ni-
Fe-Mo), permender (Co-Fe) and amorphous magnetic materials. These high-permeability materials are used to form a magnetic ink by being mixed with a binder in the form of fine particles having an easy magnetization axis such as needle-like or scale-like.

The binder mixed with the fine particles of the high magnetic permeability material is composed of a mixture of a resin and a solvent. Examples of preferable resins include polyester resin, alkyd resin, vinyl resin, polyurethane resin, and acrylic resin, and an appropriate resin is selected according to a printing method to be applied. The solvent is appropriately selected from solvents for these resins. The magnetic ink may contain, as necessary, a surfactant, a colorant, and other additives generally used in this field, in addition to the resin, the solvent, and the fine particles of the high magnetic permeability material.

The mixing ratio of the resin and the fine particles of the high magnetic permeability material is not particularly limited. However, in consideration of the adhesion to the printing surface, the strength of the coating film, the magnetic properties of the coating film, etc., the weight ratio is preferably 1: 1. :
0.1 to 1:10, optimally in the range of 1: 1 to 1: 8.

In the magnetic recording medium of the present invention, the number, shape and arrangement pattern of the magnetic layers included in the authenticity discrimination pattern are not limited, but most commonly, a bar code is used. The authenticity discrimination pattern may be formed only by an arbitrary number of magnetic layers, or a dummy non-magnetic layer may be combined.

[0012]

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

FIG. 2 is a schematic perspective view of a magnetic recording medium according to an embodiment of the present invention. In the figure,
As shown in detail in FIG. 3, a magnetic card 1 as a magnetic recording medium includes a magnetic recording layer 11, a magnetic layer 2, a non-magnetic magnetic layer 3, It has a configuration in which a silver ink layer 12 and an overcoat layer 13 are provided. The magnetic layer 2 and the non-magnetic layer 3 are in the form of a barcode provided by a suitable means such as screen printing, and form a code for authenticity determination.

As the base material 11, PET, PVC, PC
Or a synthetic resin film or paper.

As the magnetic material used to form the magnetic layer 2, the above-described high-permeability material is used. In order to obtain good properties as a magnetic ink, it is 200 μm or less, preferably 0.1 to 0.1 μm. Those having a particle size of 50 μm are used.

In this example, the magnetic material has an average particle size of 20
50 μm flaky permalloy, polyester resin 10
, A mixed solution consisting of 20 parts of cyclohexanone and 20 parts of butyl cellosolve is kneaded with a roll mill for about 1 hour to obtain a uniformly dispersed mixture. Subsequently, the mixture was diluted with a solvent in which cyclohexanone and butyl cellosolve were mixed at a ratio of 1: 1.
Adjust the viscosity to 100 poise. The magnetic ink thus obtained was applied on the base material 11 in a pattern of 1 mm in width and 5 mm in length by silk screen printing (Tetron # 250), and cut into predetermined dimensions to produce a magnetic card 1.

FIG. 4 shows the MH characteristics of the permalloy magnetic ink used in this example in comparison with the characteristics of a conventional magnetic ink using iron powder as a magnetic material. FIG. 5 shows the characteristics of a magnetic ink using Sendust instead of Permalloy as a high-permeability magnetic material.

The identification of the authenticity of the magnetic card 1 having such a configuration is performed by, for example, relatively moving a magnetic head to which a DC bias current has flowed along an arrow A shown in FIG. FIG. 6 shows a relationship between a relative positional relationship between the magnetic layer 3 and the magnetic head 4 and a detection voltage obtained from the detection coil 4 a of the magnetic head 4. FIG. 6
1, the bias coil of the magnetic head 4 is omitted.

In FIG. 6, the magnetic card 1 of the present embodiment
Is inserted into the reader and transported in the direction of arrow A,
Scanning is performed by the magnetic head 4 in which a constant magnetic flux is generated by a direct current flowing through the bias coil, and information is read. When the magnetic head 4 passes over the magnetic layer 2, magnetic coupling occurs with the magnetic layer 2 and the magnetic flux changes, so that pulse voltages in opposite directions are generated at the start and end of the magnetic layer 2. On the other hand, since no change occurs in the magnetic flux on the nonmagnetic pattern 3, no voltage is generated in the magnetic head 4.

When an oriented magnetic recording layer is formed on the surface of the base material and the AC recording is not demagnetized, detection signals in opposite directions are sent to the magnetic head 4 at the beginning and end of the magnetic card 1, respectively. Occur.

In reading the authenticity identification code, the voltages + V and -V of the detection signal obtained when the magnetic head 4 passes over the respective magnetic layers 2 vary depending on the contact state of the magnetic head 4 with the magnetic card 1. , And a stable output signal can always be obtained without being affected by the fluctuation of the bias current applied to the bias coil of the magnetic head 4.

[0022]

As described above, according to the present invention, the magnetic layer included in the authenticity discrimination pattern is made of a high magnetic permeability material that is magnetically saturated in the magnetic field applied by the read magnetic head. It is formed by magnetic ink containing. Therefore, when the magnetic head is scanned for reading the identification code, the output voltage may not fluctuate due to external factors such as a fluctuation in a relative positional relationship with the magnetic head in a range of normal use conditions. Therefore, it is possible to always perform stable authenticity identification.

[Brief description of the drawings]

FIG. 1 is an MH curve diagram for explaining the principle of a magnetic recording medium according to the present invention.

FIG. 2 is a perspective view of a magnetic recording medium according to one embodiment of the present invention.

FIG. 3 is a partial longitudinal sectional view of the magnetic recording medium of FIG. 2;

FIG. 4 is an MH curve diagram showing the magnetic characteristics of a permalloy magnetic layer used in the magnetic recording medium of FIG. 2 in comparison with a conventional magnetic layer.

FIG. 5 is an MH curve diagram showing the magnetic characteristics of a sendust magnetic layer in comparison with a conventional magnetic layer.

FIG. 6 is an explanatory diagram showing a relationship between a relative positional relationship between a magnetic layer and a magnetic head and a detection voltage of the magnetic head in a true / false determination operation.

[Explanation of symbols]

 1 Magnetic card. 2 Magnetic layer. 3 Non-magnetic layer. 4 Magnetic head. 4a Detection coil 10 Base material. 11 Magnetic recording layer. 12 Silver ink layer. 13 Overcoat layer.

Claims (4)

(57) [Claims] To 1. A magnetic recording layer provided on one surface of the substrate, in the reading method of a magnetic recording medium having a magnetic layer for authenticity identification in a predetermined pattern, the magnetic layer is high permeability A method for reading a magnetic recording medium , wherein the method is performed by applying a magnetic field that magnetically saturates the magnetic layer and is formed using a material. 2. The method for reading a magnetic recording medium according to claim 1, wherein the high-permeability material is magnetically saturated by a magnetic field of 3 k Oe. 3. The high-permeability material is fine particles having a needle-like or scale-like shape and an easy magnetization axis.
3. The method for reading a magnetic recording medium according to claim 1 . 4. The high-permeability material is sendust (Fe
-Al-Si), permalloy (Ni-Fe (-M
The method for reading a magnetic recording medium according to any one of claims 1 to 3, wherein the method is selected from the group consisting of o)), permender (Co-Fe), and an amorphous magnetic material.