JPH03122815A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To enable a card issuer to select and give any information as specific information to each card by providing a first magnetic layer and a second magnetic layer which has same patterns comprising the same material as a base material having low Curie temp. and rather high coercive force at room temp. CONSTITUTION:The first magnetic layer 3 formed on a nonmagnetic substrate 2 is used as a magnetic information track 4 usually used to record magnetic information. Further, the second magnetic layer 5 having different magnetic characteristics from the first layer is provided as the specific information track 6 to record specific information to the card. The second magnetic layer 5 has same patterns comprising the same material as the base material which has rather high coercive force at room temp. and low Curie temp. By performing thermomagnetic recording during heating the patterns in the second magnetic layer to near the Curie temp. of the material, specific information to the card can be recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a magnetic recording medium suitable for use in magnetic cards, etc., and in particular, a magnetic recording medium having a magnetic pattern to make counterfeiting difficult. It's about the medium.

2. Description of the Related Art In recent years, it has been proposed to form magnetic patterns on magnetic cards used for prepaid cards and the like for the purpose of determining authenticity. As an example of the conventional technology,
There is one disclosed in Japanese Patent No. 65644. In this conventional magnetic card, "1" or "0" representing binary information as card-specific information is expressed by the width of the magnetic pattern or the presence or absence of the pattern. An example of a conventional magnetic card is schematically shown in a partial perspective view. In this conventional magnetic card, the width of each magnetic pattern formed on the base 11 is
Like the magnetic pattern 12a and the magnetic pattern 12b,
It is changed according to the binarized information. For example, the wide magnetic pattern 12a corresponds to information "0", and the narrow magnetic pattern 12b corresponds to information "1".

FIG. 4 of the accompanying drawings is a diagram similar to FIG. 3 showing another example of configuring binary information using conventional magnetic patterns. In the conventional example shown in FIG. 4, a magnetic pattern 13 and a non-magnetic dummy pattern 14 are formed on a base 11.
The array is changed according to the binarized information. For example, the magnetic pattern 13 is made to correspond to information "1", and the dummy pattern 14 is made to correspond to information "0".

Problems to be Solved by the Invention However, if card-specific information is constructed using magnetic patterns as in the past, a pattern with a different shape and position must be formed for each card, which complicates the manufacturing process. It had drawbacks. In addition, not only when changing the width of the pattern, but also when combining a magnetic pattern and a dummy pattern, the material of each pattern is different and misalignment is likely to occur during pattern formation, so it is necessary to visually check the unique information. can be confirmed, which poses a problem in terms of security.

On the other hand, since the unique information is specified at the time of card manufacture, there is also an operational problem in that the card issuer cannot arbitrarily select a code as the unique information for each card.

An object of the present invention is to provide a magnetic recording medium that can solve the conventional problems as described above.

Means for Solving the Problems A magnetic recording medium according to the present invention includes a non-magnetic substrate, a first magnetic layer for recording magnetic information provided on the surface of the non-magnetic substrate, and a first magnetic layer provided at a specific position with respect to the non-magnetic substrate. The second magnetic layer is formed of the same material and patterned in the same shape and has a relatively high coercive force and a low Curie point at room temperature. When used as a magnetic card, when the card is issued, information specific to the card is given to each pattern of the second magnetic layer by performing thermomagnetic recording while heating the card to a temperature near its Curie point. It is something that can be done.

Embodiments The present invention will now be described in more detail with reference to embodiments of the invention, based on FIGS. 1 and 2 of the accompanying drawings.

FIG. 1 shows, in plan, a magnetic card as an embodiment of the magnetic recording medium of the present invention. The magnetic card l of this embodiment has a first magnetic layer 3 formed on the surface of a non-magnetic substrate 2, and this first magnetic layer 3 is used for recording normal magnetic information. This is used as track 4.

This magnetic card 1 is further provided with a second magnetic layer 5 having different magnetic properties from the first magnetic layer 3;
The magnetic layer 5 is used as a unique information track 6 for recording card-specific information, as will be described later.

The nonmagnetic substrate 2 may be plastic, paper, or a nonmagnetic metal plate. In particular, when plastic is used as the substrate 2, it is desirable to use a substrate made of polyethylene terephthalate (PET) or polyimide, which has excellent heat resistance. The first magnetic layer 3 has a coercive force of 2 at room temperature.
Barium ferrite powder with a Curie point of 450° C. is dispersed in a suitable resin to form an ink, and the ink is formed by gravure printing, offset printing, nozzle coating, hot stamping, or the like.

It is desirable that the coercive force of the magnetic material used for the second magnetic layer 5 at room temperature is so high that writing cannot be performed using a magnetic head used for writing in ordinary high coercive force magnetic cards.

Generally speaking, the strength of the recording magnetic field required to saturate write on a magnetic medium is said to be at least twice the coercive force of the medium, but the strength of the recording magnetic field required to write to saturation on a magnetic medium is said to be at least twice the coercive force of the medium. Since the magnetic flux density is about 10 KG, the coercive force of a medium that can be saturated with a Sendust head is 50,000 e or less. Therefore, the coercive force of the magnetic material used for the second magnetic layer 5 of the magnetic recording medium according to the present invention at room temperature must be greater than 50,000e.

On the other hand, when plastic is used as the card base, the Curie point of the magnetic material used for the second magnetic layer 5 of the magnetic recording medium according to the present invention is preferably 200° C. or lower in view of the heat resistance of the base. In this example, the coercive force at room temperature is 800
00e, gallium-substituted barium ferrite powder with a Curie point of 160°C is dispersed in a suitable resin and made into ink, which is then printed into a uniform rectangular pattern by screen printing, offset printing, letterpress printing, gravure printing, etc. They are formed in rows with a pitch.

One square pattern is one piece of unique information that identifies a card.
If n rectangular patterns are formed in the unique information track 6, n bits of information can be recorded. In this rectangular pattern, a state where the pattern is magnetized in one direction corresponds to "l", and a state where the pattern is magnetized in the opposite direction corresponds to mi "0".

In order to protect the magnetic information track 4 and the unique information track 6, a protective layer made of colored ink or the like may be provided on the magnetic information track 4 and the unique information track 6.

Next, an example of a method for recording the unique information of this magnetic card when issuing the card will be described. In order to write unique information for identifying the card into the unique information track 6 of the magnetic card according to the present invention, a writing device schematically shown in FIG. 2 is used. As shown in FIG. 2, the writing device includes a thermal head 7 for heating the second magnetic layer 5 of the magnetic card l to a temperature near the Curie point, and a thermal head 7 for heating the second magnetic layer 5 to a temperature near the Curie point. A bias electromagnet 8 that generates a magnetic field capable of saturation magnetization is provided. In addition,
In FIG. 2, arrows indicate the running direction of the magnetic card 1. In a writing device having such a configuration, the magnetic card 1 is conveyed in the direction of the arrow, and the unique information track 6 is
When one of the rectangular patterns on the top is directly above the bias electromagnet 8, a direct current is applied in a certain direction to the electromagnet 8, and at the same time, a current is applied to the thermal conductor 7 to bring the temperature of the rectangular pattern near the Curie point. Heat to reach. When the square pattern reaches around the Curie point, the current flowing through the thermal head 7 is cut off, and the temperature of the square pattern is lowered to around room temperature. During this time, if a current is passed through the bias electromagnet 8 and a constant magnetic field is applied to the rectangular pattern, the rectangular pattern is thermomagnetically recorded in one direction. When each rectangular pattern is recorded thermomagnetically while changing the direction of the current flowing through the bias electromagnet 8 while conveying the card, each pattern is
It is magnetized in a direction that corresponds to the direction of the current.

By making the direction of magnetization correspond to the binary values "0" and "1", unique information that specifies the card can be written in the unique information track 6.

When the temperature of the rectangular pattern returns to room temperature, the coercive force recovers to 80,000e, so in this state it is impossible to rewrite the fixed information with a normal high coercive force card league.

In this embodiment, the binary values "0" and "l" are made to correspond to the direction of magnetization of each rectangular pattern, but they can also be made to correspond to those with magnetization and those without magnetization. In this case, the method of magnetizing the rectangular pattern is as described above, but in order to demagnetize the rectangular pattern, no current is passed through the bias electromagnet 8, that is, without applying a bias magnetic field to the rectangular pattern. After passing a current through the Rad 7 and heating it to a temperature near the Curie point, the current is turned off and the temperature is lowered to near room temperature.

In this embodiment, a thermal head is used as the heating means of the writing device, but a laser beam may also be used. Further, although an electromagnet is used as the bias magnetic field generating means, a magnetic head or a permanent magnet may also be used.

In this way, different card specific information can be recorded on the specific information track 6 for each card.

Further, in this embodiment, the first magnetic layer 3 is formed only on the magnetic information track 4, but it is formed on the entire surface of the base 2 of the magnetic card 1, and the unique information is placed on or below the first magnetic layer 3. Tracks 6 may also be formed.

Effects of the Invention According to the present invention, card-specific information that can be detected by a magnetic sensor can be added to a magnetic card in a simple manner, and it is difficult to rewrite the unique information with a normal magnetic card writing device. Therefore, highly secure magnetic cards can be supplied at low cost. Furthermore, according to the configuration of the magnetic recording medium of the present invention, the magnetic layer for recording unique information on the card may be made of the same material and patterned in the same shape. The manufacturing process is extremely simple, and the cost can be reduced accordingly. And the information specific to the magnetic card is
There is no need to give it during the manufacturing process, and the issuer of the magnetic card can choose to give it at the time of issue.
It is considered to be extremely flexible.

[Brief explanation of drawings]

FIG. 1 is a plan view schematically showing a magnetic card as an embodiment of the magnetic recording medium of the present invention, and FIG. 2 is a schematic diagram showing an example of a writing device for the magnetic card of FIG. FIG. 3 is a partial perspective view showing an example of a conventional magnetic card, and FIG. 4 is a partial perspective view showing another example of a conventional magnetic card. DESCRIPTION OF SYMBOLS 1...Magnetic card, 2...Nonmagnetic substrate, 3...First magnetic layer, 4...Magnetic information track, 5...・Second magnetic layer, 6...
Specific information track, 7... Thermal head, 8...
...Bias electromagnet. Figure 1 Figure 4 Figure 2

Claims (4)

[Claims] (1) A non-magnetic substrate, a first magnetic layer for recording magnetic information provided on the surface of the non-magnetic substrate, and a first magnetic layer provided at a specific position with respect to the non-magnetic substrate and having a relatively high coercive force at room temperature. and a second magnetic layer patterned in the same shape and made of the same material and having a low Curie point. (2) Binarized information is recorded in the second magnetic layer by a magnetized state and a demagnetized state for each pattern (
1) The magnetic recording medium described above. (3) The magnetic recording medium according to claim 1, wherein binary information is recorded in the second magnetic layer based on a difference in the magnetization direction of each pattern. (4) The second magnetic layer has a coercive force of 50 at 25°C.
3. The magnetic recording medium according to claim 1, wherein the magnetic recording medium is made of a magnetic material having a temperature of 00 Oe or more and a Curie point of 200° C. or less.