JPH0248949B2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a method for preventing counterfeiting of magnetic cards.

In recent years, as the use of magnetic cards such as cash cards and credit cards has become widespread, crimes such as counterfeiting and misuse of cards have occurred. Here, an example of a method for forging a card in the case of a cash card is as follows.

1) Forgery by someone inside the bank The magnetic recording medium of the cash card (usually formed in the form of a stripe, commonly known as a magnetic stripe) contains the bank code number, deposit account number, and PIN number. Magnetically recorded as user information. Card counterfeiting is extremely easy for people inside the bank, especially those involved in card issuance, because they can obtain the user information.
In other words, forgery can be easily carried out by erasing the user information of the card owned by the forger by putting it into a magnetic recording device, and then magnetically recording the user information on the card of another person to be forged using the device. . In this case, the recording conditions such as the position of the first magnetic recording number (barcode) (distance from the edge of the magnetic recording medium to the first magnetic recording number) and magnetic recording density (number of bits) may be determined by the person in charge of card issuing. Since he is very knowledgeable, he can forge it without any problem.

2) In the case of forgery by an external party: User information cannot be easily obtained by an external party. However, by secretly monitoring the operation of a person withdrawing cash from an automatic teller machine, they learned the PIN number of the withdrawer's card, and also learned the PIN number of the withdrawer's card (the balance statement sent out from the payment machine along with the cash). (often thrown away)
You can find out the bank code number and deposit account number written on the statement. Therefore, the card owned by the forger can be erased from his or her own user information by using a magnetic recording device, and another person's user information obtained as described above can be newly recorded magnetically to perform forgery. In this case, when the counterfeiter's card is immersed in developer, the magnetic recording symbol (barcode) will appear as an image, and if you look at it, you can see the location of the first magnetic recording symbol, the magnetic recording density (number of bits), etc. Since the conditions can be determined, magnetic recording can be performed exactly the same as on another person's card.

As described above, since information on magnetic cards can be easily erased or newly recorded, no effective means for preventing counterfeiting has been established so far.

In view of the above points, it is an object of the present invention to provide a card counterfeit prevention method that can accurately prevent card counterfeiting.

That is, in the present invention, the coercive force of the magnetic material in the card base material is 3.
A magnetic card is constructed by forming a multilayer magnetic recording medium in which a low coercive force magnetic layer and a high coercive force magnetic layer that are different by a factor or more are laminated, and a magnetic card is provided in a card specific information recording area of the recording medium of the magnetic card. After the manufacturer records card-specific information that differs for each card using a high-field magnetic recording device that can perform magnetic recording on the high coercive force magnetic layer, magnetic recording is possible on the low coercive force magnetic layer, but the high coercive force magnetic layer The card specific information recorded on the low coercive force magnetic layer is erased using a low magnetic field magnetic recording device that cannot perform magnetic recording, thereby producing a magnetic card in which the card specific information is recorded only on the high coercive force magnetic layer. On the other hand, the card issuer records user information in the user information recording area of the low coercive force magnetic layer using a low-field magnetic recording device that can magnetically record on the low coercive force magnetic layer but not on the high coercive force magnetic layer. At the same time, it is registered in advance in a magnetic reader so that card users can be identified by a combination of card-specific information that differs for each magnetic card and user information unique to the card user, thereby preventing card counterfeiting. In addition to preventing the person from erasing the card-specific information, the card-specific information of the magnetic card of the magnetic person and the user information are used to record this information on a card with different card-specific information using a low-field magnetic recording device. 1. A method for preventing counterfeiting of a magnetic card, characterized in that even if the card is used, different card-specific information overlaps and becomes unreadable by a magnetic reader, thereby preventing counterfeiting. The gist is:

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

In FIG. 1, reference numeral 1 denotes a magnetic card used for carrying out the method of the present invention, and this magnetic card 1 includes a multilayer magnetic recording medium 4 consisting of a low coercive force magnetic layer 2 and a high coercive force magnetic layer 3 on a card base material 5. The coercive force of the magnetic material differs by at least three times between the low coercive force magnetic layer 2 and the high coercive force magnetic layer 3. That is, the coercive force in the high coercive force magnetic layer 3 has a value more than three times the coercive force in the low coercive force magnetic layer 2. The planar shape of the magnetic card 1 is shown in FIG. 8, and as shown in the figure, the recording medium 4 is formed in a striped shape. Although FIG. 1 is shown as a longitudinal cross-sectional view taken along the line X-X in FIG. 8, FIG. It is. Therefore, the hatching representing the cross section is also omitted. This situation is shown in Figure 2.
The same applies to FIG. In the present invention,
The recording medium 4 is not limited to the above-mentioned stripe shape, and the area of the recording medium 4 can be arbitrarily selected, and the longitudinal end of the recording medium 4 and the end of the card base material 5 are not aligned. It may be a composition.

The coercive forces of the magnetic layers 2 and 3 can be arbitrarily selected, and various combinations of the two are possible. Generally, the coercive force of the magnetic layer standardized in magnetic recording systems is 300 Oe, 650 Oe, 1050 Oe, and 3000 Oe, and 650 Oe is currently used in the case of cash cards. Therefore, also in the present invention, the magnetic layer 2
A magnet with a coercive force of 650 Oe can be used. In this case, the magnetic layer 3 has the coercive force of the magnetic layer 2.
Since it is necessary to have a coercive force three times or more than 650 Oe, the magnetic layer 3 may have a coercive force of 3000 Oe, for example. An example in which the coercive force of the magnetic layer 2 is 650 Oe and the coercive force of the magnetic layer 3 is 3000 Oe will be described below.

Magnetic card 1 having the above multilayer magnetic recording medium 4
After manufacturing the magnetic card 1, the magnetic card manufacturer magnetically records the card specific information a onto the recording medium 4 by applying the magnetic card 1 to a magnetic recording device. In this case, a card specific information recording area 6 is provided in the recording medium 4 in advance, and the information a is recorded in the recording area 6. For example, in FIG. 8, the area to the right of the dotted line 7 shown on the recording medium 4 is given as the card specific information recording area 6. The magnetic layer on which the card specific information a is to be recorded is not the low coercive force magnetic layer 2 but the high coercive force magnetic layer 3. Generally, when performing magnetic recording on a magnetic layer, it is necessary to apply a magnetic field that is at least three times the coercive force of the magnetic layer. Therefore, in the case of this embodiment, in order to record the card specific information a on the magnetic layer 3,
It is necessary to apply a magnetic field of 9000Oe to 10000Oe.
At this time, information a is also recorded on the magnetic layer 2 at the same time (FIG. 1B). The card specific information a to be recorded can be any card number, card symbol, etc., but must be information that specifies the card. Therefore, a certain card-specific information a is given only to a certain card, and other card-specific information is given to other cards.

Next, the magnetic card manufacturer erases the information a recorded on the magnetic layer 2 using a magnetic recording device. Generally, in order to erase information recorded on a magnetic layer, it is necessary to apply a magnetic field at least three times the coercive force of the magnetic layer, as in the case of recording. Therefore, in the case of this embodiment, it is necessary to apply a magnetic field of 2000 Oe to erase information a from the magnetic layer 2. now,
Assume that information a is erased from the magnetic layer 2 by applying a magnetic field of 2000 Oe. Here, information a of the magnetic layer 3
Since a magnetic field of at least 9000 Oe is required to erase the information, the information a of the magnetic layer 3 is not erased, and only the information a of the magnetic layer 2 is erased. In this case, if the coercive force of the magnetic layer 3 is less than three times the coercive force of the magnetic layer 2, the magnetic layer 3 will be affected and may be demagnetized. In the present invention, since the coercive force of the magnetic layer 3 is three times or more greater than the coercive force of the magnetic layer 2, such a problem does not occur. However, the magnetic layer 3
A magnetic card 1 is obtained in which the card specific information a is recorded only on the card (FIG. 1C).

Next, the magnetic card issuer (for example, a bank, credit card company, etc.) places the magnetic card 1 on a magnetic recording device to magnetically record the user information b as before, and also records the card user's identification using the card unique information a.
and the user information b are registered in the magnetic reading device. In this case, recording medium 4
Recording is performed in the user information recording area 8 of . In FIG. 8, the area to the left of the dotted line 7 shown on the recording medium 4 is given as the user information recording area 8. Currently, the magnetic recording devices installed in banks, credit card companies, etc. have a magnetic field of about 2000 Oe, so when magnetic card issuers record user information, the information b is recorded only on the magnetic layer 2, and the magnetic 3 is not recorded. The user information b may be of the same type as conventional ones; for example, in the case of a cash card, a bank code number, deposit account number, PIN number, etc. are used as the user information b. Thus, a magnetic card 1 is issued in which card specific information a is recorded in the high coercive force magnetic layer 3 of the card specific information recording area 6 and user information b is recorded in the low coercive force magnetic layer 2 of the user information recording area 8. (Figure 1D).

Next, we will discuss the principles of counterfeit prevention using cash cards as an example.

First, we will discuss a case where someone inside the bank uses an unissued card to forge a card. In an unissued card, as shown in FIG. 2A, no user information is recorded in the magnetic layer 2, but card specific information a is recorded in the magnetic layer 3. Here, it is assumed that "1" is recorded as the card specific information a. It is assumed that the card counterfeiter uses this card to record the unique card information and user information of another person, which the card forger came to know in the course of his/her work. Here, it is assumed that the other person's card specific information a is "2". in this case,
As mentioned above, the magnetic recording devices installed in banks have a magnetic field of about 2000 Oe, so the card specific information a and user information b are recorded only on the magnetic layer 2, and are not pre-recorded on the magnetic layer 3. It is also not possible to delete the card-specific information. Therefore, card unique information "2" and "1" are recorded in the card unique information recording area 6 in a vertically overlapping manner (FIG. 2B). When a counterfeiter attempts to withdraw cash by using this counterfeit card from an automatic teller machine installed at a bank, the waveforms of the card-specific information "1" and "2" are synthesized in the magnetic reader, causing noise. occurs, and as a result, the device is unable to read the card-specific information and no cash is withdrawn. Also recording area 6
If the card specific information “2” is not recorded in
Since the combination of card specific information a and user information b becomes different, the device generates an unsuitable signal, and cash withdrawal is also not performed.
In addition, as mentioned above, the magnetic recording devices that card counterfeiters can usually use are low-field magnetic recording devices that can magnetically record on the low coercive force magnetic layer but cannot magnetically record on the high coercive force magnetic layer. It is not possible to erase the card specific information "1" previously recorded in the magnetic magnetic layer.

Next, we will discuss the case where someone inside the bank or someone outside the bank uses their own card to forge a card.
Card-specific information a and user information b are recorded on the card owned by the forger, as shown in FIG. 3A, and it is assumed here that card-specific information a is "3". A counterfeiter attempts to erase the information recorded on his own card and newly record information on another person's card. Here, as mentioned above, since the magnetic recording device that can be used by bank officials or outsiders has a magnetic field of about 2000 Oe, the user information b recorded in the magnetic layer 2 can be erased, but the Recorded card specific information “3”
remains without being erased (Figure 3B). On this card,
Assume that card unique information a and user information b of another person's card, which were known through some means, are recorded. Here, it is assumed that the card unique information a of the other person is "2" as described above. For the same reason as mentioned above, the information a and b are recorded only on the magnetic layer 2, and the card specific information "2" and "3" are recorded vertically overlapping each other (FIG. 3C). Even if this card is used, a magnetic reader cannot read it for the same reason as mentioned above, so crimes are prevented.

Also, if only the user information of another person's card is recorded, the combination of card-specific information and user information will be different, so if this card is used, the magnetic reader will generate an inappropriateness signal and crime will be prevented. Ru.

Next, one of the card manufacturing methods applied to the present invention
Let me give an example.

Figure 4 shows the case of manufacturing by the transfer method, in which a release layer 10, a low coercive force magnetic layer 2, a high coercive force magnetic layer 3, and an adhesive layer (heat seal type) 11 are sequentially laminated on a support 9. The magnetic transfer tape formed by the magnetic transfer tape is brought into close contact with the card base material 5 via the adhesive layer 11, heated and pressed to perform thermal transfer, and then the support 9 is peeled off (FIG. 4A), and further heat and pressure is applied to the card base material. 5 so that they are flush with each other (Fig. 4B). Support 9
As the release layer 10, a polyester resin or butyral resin or the like having a thickness of 1 to 3 microns can be used, and as the card base material 5, a vinyl chloride resin or the like can be used. The thickness of the adhesive layer 11 is usually 5 to 10 microns. The thickness of each of the magnetic layers 2 and 3 is usually 10 to 15μ,
And the residual magnetic flux of these magnetic layers is 1.4maxwell/
cm is usually used.

In order to prevent interaction between the magnetic layers 2 and 3 (for example, when laminating the magnetic layers 2 and 3, the surface of the lower layer is dissolved by a solvent and becomes uneven), as shown in FIG. A barrier layer 12 having a thickness of 10 μm or less is preferably interposed between the magnetic layers 2 and 3. A synthetic resin film as the barrier layer 12,
Aluminum foil or the like can be used.

FIG. 6 shows a case of manufacturing by a coating method, in which a magnetic layer 3 is provided on a card base material 5, a protective layer 13 made of, for example, a synthetic resin film.
are sequentially coated and heated and pressed to embed them in the card base material 5 so that they are flush with each other.

FIG. 7 shows a case of manufacturing by a lamination method, in which a magnetic layer 3, a magnetic layer 2, and a protective layer 13 are sequentially laminated on a base film 14, with the base film 14 facing the card base material 5. It is attached to the card base material 5 via the adhesive layer 15 so as to become flush with each other by heating and pressurizing it and embedding it in the card base material 5. The barrier layer 12 can also be provided between the magnetic layers 2 and 3 in the structures shown in FIGS. 6 and 7. In addition, Figures 4B to 7 are Y-Y in Figure 8.
A line longitudinal cross-sectional view is shown.

As explained above, the present invention has a multilayer magnetic layer, which is separated into a low coercive force magnetic layer and a high coercive force magnetic layer, and the magnetic card manufacturer magnetically records card-specific information on the high coercive force magnetic layer. As before, the magnetic card issuer records user information magnetically on the low coercive force magnetic layer, and the card user is identified by the combination of user information and card-specific information. In addition to the conventional user information, card specific information is also checked, and since it looks like there is a single magnetic layer, this is useful in preventing card forgery. Moreover, since the coercive force between the low coercive force magnetic layer and the high coercive force magnetic layer is more than three times different, card-specific information recorded on the high coercive force magnetic layer can be counterfeited using a commonly used magnetic recording device. Since it is impossible for a person to erase the card and, therefore, it is impossible to change the card-specific information, it is possible to reliably prevent card forgery.

Next, specific examples of the present invention will be shown.

Example After magnetically recording predetermined card specific information in the card specific information recording area of a multilayer magnetic recording medium of a magnetic card using a magnetic recording device with a magnetic field of 10000 Oe, the card specific information of the low coercive force magnetic layer is recorded with a magnetic field of 2000 Oe. was deleted. Then 2000Oe
Predetermined user information was recorded in the user information recording area using a magnetic field. The user information was erased using a magnetic field of 2000 Oe, and user information and card specific information different from the user information and card specific information were recorded using the same 2000 Oe magnetic field. When this magnetic card was placed in a magnetic reader, noise was observed and the card could not be read.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention; FIG. 1 is an explanatory diagram showing the process of magnetic recording, FIGS. 2 and 3 are explanatory diagrams showing the process of card forgery, and FIGS. FIG. 8 is a longitudinal sectional view showing various configuration examples of a magnetic card used in carrying out the method of the present invention, and FIG. 8 is a plan view thereof. 1...Magnetic card, 2...Low coercive force magnetic layer, 3
...High coercive force magnetic layer, 4...Multilayer magnetic recording medium,
5... Card base material, 6... Card specific information recording area, 8... User information recording area, a... Card specific information, b... User information.

Claims (1)

[Claims] 1. Construct a magnetic card by forming a multilayer magnetic recording medium in which a low coercive force magnetic layer and a high coercive force magnetic layer, each of which has a different coercive force of magnetic materials by three times or more, are laminated on a card base material, and After a magnetic card manufacturer records card-specific information that differs for each card in the card-specific information recording area of the recording medium using a high-field magnetic recording device that can perform magnetic recording on a high-coercive force magnetic layer, a low-coercive-force magnetic layer is recorded. Card-specific information recorded in the low coercive force magnetic layer is erased using a low-field magnetic recording device that can magnetically record on the layer but not on the high coercive force magnetic layer, thereby leaving only the high coercive force magnetic layer. The card issuer manufactures a magnetic card with card-specific information recorded on it, and the card issuer uses a low-field magnetic recording device that can record magnetically in the low-coercivity magnetic layer but not in the high-coercive-force magnetic layer. User information is recorded in the user information recording area of the magnetic layer, and the card user is identified by a combination of card-specific information that differs for each magnetic card and user information specific to the card user. It is registered in advance in a magnetic reader to prevent a card counterfeiter from erasing the card-specific information, and the card-specific information and user information of another person's magnetic card are used to store this information in a low-field magnetic recording device. A method for preventing counterfeiting of a magnetic card, characterized in that even if unique card information is recorded on different cards and used, the different card unique information overlaps and becomes unreadable by a magnetic reader, thereby preventing counterfeiting. Method.