JP3044124B2 - Magnetic card and method for preventing unauthorized use thereof - 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 card suitable for use in a prepaid card, and more particularly to a magnetic card and a method for preventing unauthorized use such as falsification of magnetic signals and forgery. is there.

[0002]

2. Description of the Related Art In recent magnetic cards, a prepaid card called a prepaid card has been widely used. However, since this prepaid card is treated like a voucher in the market, data tampering,
Unauthorized use such as forgery must be prevented, and various devices have been devised so far.

For example, there is a method disclosed in Japanese Patent Application Laid-Open No. 62-35992 in which two types of information, magnetic information and punching information, are collated. According to this method, for example, information such as the expiration date of a magnetic card is recorded as a magnetic signal, and the same information is provided with a perforation at a predetermined position on the magnetic card, thereby providing two types of information, magnetic information and perforation information. The information is recorded as information, the magnetic information is read by a magnetic head, and the perforation information is read by an optical sensor for comparison and judgment, thereby performing a double check to prevent falsification and forgery.

[0004]

However, such a conventional method requires a cost because a punching device is installed in a magnetic card reader, and also makes it impossible to punch a punching information portion with a tape or the like. The perforations can be drilled at different locations by piercing. In addition, since the magnetic layer can be easily falsified as long as it is recorded and reproduced with a normal magnetic head, it is not sufficient as a method for preventing unauthorized use.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to propose a magnetic card which makes it difficult to falsify or forge a magnetic signal and a highly effective method for preventing unauthorized use. According to the present invention, there is provided a magnetic card having a magnetic layer on a non-magnetic substrate and a thermosensitive coloring layer on the magnetic layer, wherein the magnetic layer has a relatively high coercive force at room temperature, and has a low It has a Curie temperature, and the coloring temperature of the thermosensitive coloring layer is equal to or lower than the Curie temperature of the magnetic layer. More specifically, the magnetic card of the present invention is a magnetic card having a magnetic layer on a non-magnetic substrate and a thermosensitive coloring layer on the magnetic layer, wherein the magnetic layer has substantially no writing at room temperature. It has a relatively high coercive force that cannot be obtained and has a relatively low coercive force that can be written with a heat-resistant magnetic head at a heating temperature below the Curie temperature, and the coloring temperature of the thermosensitive coloring layer is not more than the Curie temperature of the magnetic layer And at least the heating temperature. When using this magnetic card, in an atmosphere at a temperature lower than the coloring temperature of the thermosensitive coloring layer and as high as possible,
A magnetic signal is recorded on the magnetic layer. The magnetic card having the magnetic recording in a state where the thermosensitive coloring layer thus obtained is not colored is delivered to the user.

When a user uses this magnetic card in a telephone, for example, the machine heats a magnetic signal portion corresponding to a used value among magnetic signals recorded on the magnetic layer while heating the magnetic signal portion to a temperature higher than the Curie temperature of the magnetic layer. Erase, and at the same time, color the thermosensitive coloring layer on the erased magnetic signal portion. The erased portion of the magnetic signal recorded on the magnetic layer and the colored portion of the thermosensitive coloring layer are positionally equal, and by comparing this, the authenticity of the value information of the magnetic card is determined.

[0007]

Next, embodiments of the present invention will be described in detail. FIG. 1 is a sectional view of a magnetic card as one embodiment of the present invention. In this embodiment, a magnetic layer 2 having a relatively high coercive force at room temperature and a low Curie temperature is formed on a non-magnetic substrate 1, and the magnetic layer 2 is formed on the magnetic layer 2.
The thermosensitive coloring layer 3 having a coloring temperature lower than the Curie temperature is formed.

The non-magnetic substrate 1 may be made of plastic, paper or a non-magnetic metal plate. Particularly, when plastic is used, polyethylene terephthalate, polyethylene naphthalate, polyetherimide, polyamide having excellent heat resistance is used. Alternatively, it is preferable to use a polyimide resin substrate. The magnetic layer 2 needs to have a relatively high coercive force at room temperature and a low Curie temperature.

The coercive force of the magnetic layer 2 used in the present invention needs to be large enough that a normal magnetic head used for a normal high coercivity magnetic card cannot sufficiently record saturation. The coercive force of a normal high coercivity magnetic card is 3000O
e, the coercive force of the magnetic layer 2 is preferably 5000 Oe or more in order to achieve the present invention, and the Curie temperature is set to 200 ° C. for easy thermal demagnetization with a thermal head or the like.
The following is preferred. Examples of the magnetic material that enables such a magnetic layer 2 include oxide-based materials such as barium ferrite substituted with Ga, Al, Cr and the like, and Sr-ferrite substituted with Ga, Al, Cr and the like. Other Sm-Co system,
Nd—Fe—B based metal materials are also possible.

The thermosensitive recording layer 3 needs to develop a color below the Curie temperature of the magnetic layer 2. The heat-sensitive coloring layer is not particularly limited as long as it forms a color below the Curie temperature of the magnetic layer. A leuco dye-based heat-sensitive coloring layer is preferably used as having a relatively low temperature and high sensitivity coloring property.

Next, the features of the magnetic card of the present invention will be described in more detail with reference to embodiments. First, a magnetic layer made of a Ga-substituted barium ferrite magnetic material having a coercive force of 7.2 kOe and a Curie temperature of 140 ° C. was formed on a polyetherimide substrate having a thickness of 250 μm. As a method for forming a magnetic layer, a magnetic material pulverized to an average particle size of 1 μm or less is prepared into a coating material having the following composition, and this is coated on a substrate with a thickness of 10 μm.
By applying so as to be μm, the flexibility is improved,
A magnetic layer suitable for a magnetic card could be formed. Magnetic material 100 parts by weight Surfactant 3 Vinyl chloride resin 15 Urethane resin 10 Solvent 200 A thermosensitive coloring layer having a coloring temperature of 120 ° C. was formed on the magnetic layer.

As a method for forming the thermosensitive coloring layer, a coating material was prepared with the following composition, applied to a thickness of 5 μm, and punched into a card shape. Leuco dye 2.5 parts by weight Acid developer 7.5 Acrylic resin 10.0 Distilled water 50.0 Figure 2 shows Fe-A of magnetic card produced in this way.
Recording current characteristics at room temperature with an l-Si alloy head and F
This is a graph showing recording current characteristics of an e-Co alloy head in an atmosphere at 80 ° C. According to FIG. 2, the Fe--Al--Si alloy head cannot record a magnetic signal sufficiently at room temperature. This means that the magnetic card of the present invention has a high coercive force at room temperature of 7.2 kOe, so that it is not possible to perform sufficient recording with a magnetic head that is normally used. However, Fe-C
If an o-alloy head is used, a magnetic signal can be recorded. This is because the coercive force of the magnetic layer decreases as the temperature approaches the Curie temperature, so that the coercive force of the magnetic layer is lowered in an atmosphere at a temperature as high as possible, lower than the coloring temperature of the thermosensitive coloring layer. Co alloy, PB
A magnetic signal is recorded by a special magnetic head having a high saturation magnetic flux density such as a permalloy alloy. That is, the recording of the signal of the magnetic card of the present invention requires a specific temperature condition, and is achieved only by using a special magnetic head which is generally difficult to obtain.

FIG. 3 shows the thermal demagnetization characteristics of the magnetic card. When heated above the Curie temperature of 140 ° C., the magnetic signal is erased. FIG. 4 shows the coloring characteristics of this magnetic card. The thermosensitive coloring layer does not develop color at the temperature of 80 ° C. used for recording magnetic signals, but develops color when heated to 120 ° C. or higher. By setting the coloring temperature of the thermosensitive coloring layer to be equal to or lower than the Curie temperature of the magnetic layer, and applying heat above the Curie temperature to erase the magnetic signal, the thermosensitive coloring layer will develop color. With the magnetic card of the present invention, it is extremely difficult to falsify data at room temperature. If the magnetic card is heated and data is to be tampered with, the data must be heated to around the Curie temperature of the magnetic layer and the coercive force must be sufficiently reduced in order to rewrite the data with a commonly available magnetic head. Under such conditions, the thermosensitive coloring layer develops a color and cannot be used. FIG. 5 schematically shows a cross-sectional view of a magnetic card when a part of a magnetic signal is erased by a thermal head and a thermal coloring layer is simultaneously colored. 4 is a magnetic layer having magnetic recording, 5 is an uncolored thermosensitive coloring layer, 6 is a thermally demagnetized magnetic recording layer, and 7 is a colored thermosensitive coloring layer.

[0014]

Since the magnetic card shown above has a relatively high coercive force at room temperature, the recording head,
And the setting of recording conditions are special. Further, since the coloring temperature of the thermosensitive coloring layer is lower than the Curie temperature of the magnetic layer, the erasing of the magnetic signal and the display of the balance can be easily and simultaneously performed by a thermosensitive head or the like, so that the cost can be reduced. Further, since the erased portion of the magnetic signal and the balance display portion are equal in position, it is extremely difficult to tamper with or forge the magnetic signal by collating and authenticating the magnetic signal.

[Brief description of the drawings]

FIG. 1 is a sectional view of a magnetic card according to the present invention.

FIG. 2 shows that the magnetic card of the present invention is Fe-Al-Si at room temperature.
Fe-Co in an 80 ° C atmosphere with an alloy head
4 is a graph showing recording current characteristics when an alloy head is used.

FIG. 3 is a graph showing the thermal demagnetization characteristics of the magnetic card of the present invention.

FIG. 4 is a graph showing the thermal coloring characteristics of the magnetic card of the present invention.

FIG. 5 is a cross-sectional view when a signal is recorded on the magnetic card of the present invention, a part is erased by a thermal head, and color is simultaneously developed.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Non-magnetic base 2 Magnetic layer 3 Thermal coloring layer 4 Magnetic signal recording part 5 Thermal coloring layer before coloring 6 Magnetic layer after thermal erasing 7 Thermal coloring layer after coloring

Claims (4)

(57) [Claims] 1. A magnetic card having a magnetic layer on a non-magnetic substrate and a thermosensitive coloring layer on the magnetic layer, wherein the magnetic layer has a relatively high coercive force which cannot be substantially written at room temperature. And has a relatively low coercive force that allows writing at a heating temperature equal to or lower than the Curie temperature, and the coloring temperature of the thermosensitive coloring layer is equal to or lower than the Curie temperature of the magnetic layer and equal to or higher than the heating temperature. Magnetic card. 2. The magnetic layer according to claim 1, wherein:
A recording method, wherein a magnetic signal is recorded in an atmosphere at a temperature lower than the coloring temperature of the thermosensitive coloring layer and as high as possible. 3. The magnetic card according to claim 1, wherein a magnetic signal portion corresponding to a used value among magnetic signals recorded on the magnetic layer is erased while heating the magnetic layer to a temperature equal to or higher than the Curie temperature. A method of erasing and displaying a balance, characterized in that a thermosensitive coloring layer on an erased magnetic signal portion is colored. 4. The method according to claim 1, wherein the authenticity of the monetary value of the magnetic card is determined by comparing an erased portion of a magnetic signal recorded on the magnetic layer with a colored portion of the thermosensitive coloring layer. Characteristic judgment method.