JPH01275193A - Magnetic card and discrimination method - Google Patents

Abstract

PURPOSE:To enable accurate discrimination to be performed when unfair alternation is performed, by a method wherein a second magnetic layer having less coercive force than coercive force of a magnetic layer is established in a specific area. CONSTITUTION:A second magnetic layer 6 is firstly magnetized in the same direction as a magnetized direction of a magnetic layer 3 in a discrimination track with a recording head. When this part is reproduced with a reproducing head at that time, a large output in which both are collected is generated. Then, when the second magnetic layer 6 is magnetized reversely to the magnetized direction of the magnetic layer 3, only a slight output 10 is generated even though said part is reproduced with the reproducing head. For a judging method for justification of this card, the second magnetic layer 6 is magnetized in the same direction as the magnetized direction of the magnetic layer 3, and the number of output pulses reproduced at that time and time when said pulse appears are read, which are referred to information thereof recorded in an information recording track 4. Thereafter, the second magnetic layer 6 is reversely magnetized and is reproduced with the reproducing head. At that time, in the case of a card of a formal structure, no output pulse is detected.

Description

DETAILED DESCRIPTION OF THE INVENTION According to the present invention, when the second magnetic layer is magnetized in the same direction as the first magnetic layer, the leakage magnetic flux from the perforated portion is detected as the sum of one magnetic flux from both magnetic layers. On the other hand, when the second magnetic layer is magnetized in the opposite direction, the leakage magnetic fluxes from the perforated portion cancel each other out, resulting in a small output. Therefore, by comparing the forces of both rivers, it is possible to reliably read out the perforated portion.

Now, even if a non-magnetic mask is placed over the perforation area with the intention of tampering, the presence of the perforation will be easily detected. On the other hand, even if a magnetic mask such as a magnetic tape is applied to this area, the presence of perforations can be easily detected because a normal magnetic tape has a low coercive force. These points will be explained in detail later.

(Explanation of Examples) The present invention will be described in detail below with reference to Examples.

FIG. 1 is a plan view of a magnetic card as an embodiment of the present invention, and FIG. 2 is a cross-sectional view taken along line AA' in FIG. 1. This magnetic card 1 has a substrate 2 made of polyethylene terephthalate film having a thickness of 188 μm, and a magnetic layer 3 having a coercive force of 3000 oersteds is uniformly coated on one side of the entire surface of the substrate 2. At the specified position of the magnetic layer 3, an information recording track 4 is provided for magnetically recording and reproducing information such as card issuer information, card type, amount of money spent, and number of times of use. Further, at another specified position of the magnetic layer 3, an identification track 5 is provided which is DC magnetized in one direction over its entire length. Such DC magnetization may be done by magnetizing the identification track 5 with a recording head, or
The magnetic field orientation when the magnetic layer 3 is applied may be used.

On the identification track 5, a second magnetic layer 6 having a coercive force lower than that of the magnetic layer N3, for example, 300 oersted, is formed in a stripe shape. The magnetic layer 6 may be applied in stripes, magnetically printed using an offset or screen printer, or formed by hot stamping. A colored layer 7 is provided on the magnetic layer 3 and the second magnetic layer 6 to hide the color of the magnetic layer, that is, the brown or black hue. A magnetic discontinuity is provided along the center of the identification track 5 by a through hole 8 having a diameter of 2 mm.

Next, the operation when using this magnetic card will be explained.

When this magnetic card is inserted into a terminal, the data is reproduced on the information recording track 4, but at this time, the validity of the card is simultaneously determined using the identification track 5 without immediately processing the reproduced data. .

That is, in the identification track 5, the recording head first records the second
The magnetic layer 6 is magnetized in the same direction as the magnetization direction of the magnetic layer 3. FIG. 3 shows the state of magnetization in the cross section of the discontinuous portion of the identification track 5 at this time.

As shown in the figure, in the discontinuous part, the magnetic layer 3 and the second magnetic layer 6
are each magnetized in the same direction, creating magnetic poles of the same polarity. Therefore, when this portion is reproduced with a reproducing head, a large output 9 is generated, which is the sum of both. Next, the direction of the current flowing through the recording head is reversed to magnetize the second magnetic layer 6 in the opposite direction to the magnetization direction of the magnetic layer 3. At this time, the strength H of the magnetic field generated from the recording head is set to satisfy H6x<H<Hc+, where the coercive force of the magnetic layer 3 is Hc and the coercive force of the second magnetic layer is HC2. That is, the strength is set so that only the second magnetic layer can be magnetized. FIG. 4 shows the state of magnetization in the cross section of the discontinuous portion of the identification track 5 at this time. magnetic layer 3
Since the direction of magnetization of the second magnetic layer 6 is reversed, magnetic poles of opposite polarity are generated at the discontinuous portion of the magnetic layer due to the through hole, as shown in the figure, and a closed magnetic path is established at that portion. Since this portion is formed, almost no magnetic flux leaks to the outside, and even if this portion is reproduced with a reproducing head, only a small output of 10 is generated.

The method for determining the validity of this card is to first magnetize the second magnetic layer 6 in the same direction as the magnetization direction of the magnetic layer 3, and then check the number of output pulses reproduced and the time at which the pulses appear. The information is read and compared with the information recorded on the information recording track 4. After that, the magnetic layer 6 of the cylinder 2 is replaced with the magnetic layer 3.
It is magnetized in the opposite direction to the direction of magnetization and reproduced by a reproducing head. At this time, if the card has a normal structure, no output pulse will be detected. Next, a description will be given of the operation when a magnetic material such as a commercially available cassette tape is pasted on the identification track 5 of this card to mask the perforations, and then the magnetically recorded information is tampered with. FIG. 5 shows a cross-sectional view of a discontinuous portion caused by perforation of an altered card, and in the figure, reference numeral 1 denotes the magnetic card according to the present invention explained in FIGS. 1 and 2. 13 is a commercially available magnetic tape such as a cassette tape, 14 is a polyester film base having a thickness of 12 μm, and 15 is a magnetic layer having a coercive force of about 360 oersteds. The magnetic tape 13 and the magnetic card 1 are bonded together with an adhesive (not shown). When such an altered card is inserted into a terminal, the recording head magnetizes the magnetic layer 15 of the magnetic tape 13 in the same direction as the magnetization direction of the magnetic layer 3 of the magnetic card 1 in the identification track. FIG. 6 shows the state of magnetization in the cross section of the discontinuous portion due to the perforation of the identification track 5 at this time. The magnetic layer 15, the magnetic layer 3 and the second magnetic layer N6 of the magnetic tape 13 are each magnetized in the direction of the arrow, but the distance from the magnetic layer 3 and the second magnetic layer 6 to the card surface is colored M7, magnetic The total thickness of the base 14 of the tape 13 and the magnetic layer 15 is about 20 to 30 μm, and the magnetic flux due to the magnetization of the magnetic layer 3 and the second magnetic layer 6 does not reach the card surface.

Therefore, when this discontinuous portion is reproduced by the reproducing head, an output voltage 16 exceeding the threshold level 11 is generated due to the magnetic flux caused by the magnetic layer 15 of the magnetic tape 13, so that a reproducing pulse 17 is obtained. In the same figure, the direction of magnetization of the second magnetic layer 6 is the same as that of the magnetic layer 3, but even if it is reversed, the output voltage of the reproducing head does not change for the reason mentioned above.

Next, the direction of the current flowing through the recording head is reversed, and the magnetic J'i 15 of the magnetic tape 13 is magnetized in the opposite direction to the magnetization direction of the magnetic layer 3. A cross-sectional view of the discontinuous portion of the identification track 5 at this time is shown in FIG. At the discontinuous portion caused by the through hole, a magnetic pole of the opposite polarity to that shown in FIG. 6 is generated in the magnetic layer 15 of the magnetic tape 13, as shown in the figure. When this part is reproduced with a reproducing head, the output voltage 1 has a different polarity from that shown in Figure 6, but the peak value is the same.
8 is generated and a reproducing pulse 19 is obtained.6 In other words, unlike when reading a regular card, a reproducing pulse is also generated when the direction of the current flowing through the recording head is reversed, so it is easy to detect a counterfeit card. can. In this method, after determining the validity of the card in identification track 5,
Since various processes are performed and the information recording track is rewritten, counterfeiting of the card becomes difficult and security can be improved.

In this embodiment, the identification track 5 is read after the second magnetic layer 6 is magnetized in the positive and negative directions by the recording head, but it may be carried out while generating a DC magnetic field from the read head. In this case, the DC magnetic field H6 is also HC2
Set so that < Hs < Hc+ is satisfied. In addition, in this embodiment, the second magnetic layer 6 having a lower coercive force than the recording layer 3 is laminated only on the identification track 5 portion of the magnetic card l, but the coercive force of the entire card including the information recording track 4 is laminated. A two-layer structure covered with a low second magnetic layer results in a magnetic card with higher safety, as disclosed in Japanese Patent Application Laid-Open No. 63-34727.

Further, the magnetic discontinuity of the identification track 5 may also be used as a perforation for displaying the amount spent, the remaining amount, the number of uses, the remaining number of uses, etc. as visual information, depending on the usage status of the card.

(Effects of the Invention) In the magnetic card of the present invention, even if it is forged by pasting magnetic tape on the identification track or filling the through hole with the magnetic member of another magnetic card, the presence of a discontinuous portion can be detected very easily. , it is possible to prevent counterfeiting of magnetic cards.

The magnetic material laminated on the identification track can be an inexpensive material such as gamma iron oxide, and the processing method can be a method that is easy to mass produce, such as printing, so the cost of the card does not increase.

[Brief explanation of the drawing]

FIG. 1 is a plan view of the magnetic cart of the present invention, FIG. 2 is a sectional view taken along line A-A in FIG. 1, FIG. 3 is a diagram explaining the first stage of identification of the magnetic cart of the present invention, and FIG. 5 is a cross-sectional view of a tampered magnetic card, and FIG. 6 is a diagram illustrating the first step of tampered magnetic card identification. and FIG. 7 are diagrams illustrating the second stage of identifying a falsified magnetic card. f'--2. Name of agent Motohiro Kurauchi Go-shi- /''\X Hiroshi Kazama1,;\,-1-
/ Figure 5 Date Figure 6: Knee - Yarn Dai I Uho Masagi Arrival (Method) July 29, 1988

Claims (4)

[Claims] (1) A magnetic card in which a first magnetic layer for recording magnetic information is provided by applying a magnetic material, and in which a discontinuous portion is formed by perforating a specific area of the magnetic card. A magnetic card characterized in that the region is provided with a second magnetic layer having a coercive force smaller than that of the magnetic layer. (2) The magnetic card according to item 1, wherein the first magnetic layer is magnetized in one direction in advance in the specific area. (3) The magnetic card according to item 1 above, wherein the perforations are formed according to the number of times of use. (4) The second magnetic layer of the magnetic card according to item 2, in which the first magnetic layer is magnetized in one direction in advance, is magnetized in the direction, and then the second magnetic layer is magnetized in the opposite direction. 1. A method for identifying a magnetic card, characterized by detecting a change in magnetic flux in a perforated part when the card is pressed.