JPH0687284B2 - Method for preventing forgery of magnetic recording medium - Google Patents

Description

The present invention relates to a method for preventing forgery of a magnetic recording medium applied to a cash card of a toll collection system for toll roads.

(Prior Art) Conventionally, in order to prevent forgery of a magnetic recording medium, it is important not to transfer the magnetic recording content. As a method of solving this, the magnetic recording medium is made to have a two-layer structure of a magnetic low coercive force layer and a high coercive force layer, noise of which meaning is unknown is encoded in the low coercive force layer, and a normal coercive force layer is encoded in the high coercive force layer. It has been practiced to encode information and erase the noise of the low coercive force layer when reading the information, and then read the information of the high coercive force layer (Japanese Patent Publication No. 43-185).

In addition, a method of magnetically recording information peculiar to a card on each magnetic card, for example, information obtained by coding a fiber pattern of paper, and collating the magnetic recording contents with the information peculiar to the card has been implemented (Japanese Patent Laid-Open No. Sho 61-206). 57-97188).

(Problems to be Solved by the Invention) However, according to the conventional technology, there are the following problems. That is, in the case of a two-layer magnetic recording medium, two
It is necessary to apply a magnetic recording layer. Further, an apparatus for writing magnetic recording information on a magnetic recording medium or for reading the magnetic recording information requires an additional head for writing and reading a noise signal, resulting in high manufacturing cost.

Further, even if the recorded contents cannot be copied on the magnetic recording medium, it is possible to erase the written information and manufacture a new card, and it is not possible to reliably prevent forgery.

Further, the device for coding the information peculiar to the card described in JP-A-57-97188 has a problem that the cost is generally high.

Therefore, the object of the present invention is not to use the two-layer magnetic recording medium whose cost is high as described above.
An object of the present invention is to provide a method for preventing forgery of a magnetic recording medium which uses a layered magnetic recording medium and further prevents the recorded contents from being copied without coding a pattern.

(Means for Solving the Problems) In the present invention, in order to achieve the above object, a region where the easy axis of magnetization of the magnetic body is arranged in the plane direction of the base body and the easy axis of magnetization of the magnetic body are provided on the base body. On the other hand, in a magnetic recording medium which is arranged in a vertical direction or at a certain angle with respect to this arrangement direction and in which a plurality of areas in which the arrangement is disturbed are provided, the distance between the areas in which the arrangement is disturbed is This distance information is coded by an electric means, the coded information is recorded in an area arranged in one horizontal direction of the magnetic body, and the coded information is read when reading the information from the magnetic recording medium. It is a method for preventing forgery of a magnetic recording medium, characterized in that the information is compared and collated with the distance information, and if they match, it is judged as a genuine note.

(Operation) Therefore, in the present invention, since the magnetic recording medium of one layer is used, the manufacturing cost is reduced, and further, when a plurality of different orientation portions are provided from the horizontal direction at the time of manufacturing, they are different for each magnetic recording medium. By setting the distance, it is possible to encode different distance information on all cards, and this information is unique to the magnetic recording medium. It will be impossible. Further, measuring the distance information electrically by means is different from the pattern recognition as disclosed in Japanese Patent Laid-Open No. 57-97188 described in the conventional example, so that it is possible to accurately and accurately identify the medium by a simple method. The information of can be read.

(Embodiment) An embodiment of the present invention will be described below with reference to FIGS. 1 to 8. Here, FIG. 1 shows the shape of the magnetic recording medium,
FIG. 2 is a diagram showing a detection output waveform from the magnetic head. In the figure, 11 is a magnetic read head and 12 is a detection coil.
13 is a magnetic layer, for example barium ferrite (Ba
O.6Fe ₂ O ₃ ) is not an extremely needle-like crystal, and
A magnetic material having a relatively large magnetic anisotropy, together with a binder and a melting material, is applied onto a substrate 16 such as plastic.

Reference numeral 14 denotes a region in which the easy axis of magnetization (C axis) is arranged (oriented) in parallel with the traveling direction of the magnetic write (read) head, and 15 denotes a region in which the easy axis of magnetization is oriented in the vertical direction.
Such a magnetic recording medium is realized by applying a binder and a melting material to the substrate 16 at the same time, and then applying lines of magnetic force in a direction in which the magnetic field is desired to be magnetized by an electromagnet or the like in a relatively fluid state.

Reference numeral 21 indicates a detection output level from the magnetic read head 11, and the detection output signal is embodied by amplifying the output signal from the detection coil 12 of the read head 11. The write signal is modulated at a certain frequency, and the signal output is the direct current detection of the written signal. Therefore, in the region 15 in which the easy axis of magnetization is oriented in the vertical direction, the lines of magnetic force are orthogonal to the easy axis of magnetization, and the lines of magnetic force are the highest.
On the other hand, when the easy axis of magnetization is oriented in the direction of travel with respect to the read head (write head), the lines of magnetic force are parallel to the easy axis of magnetization, and are thus most easily magnetized.

FIG. 3 shows a coded state of the forgery prevention pattern according to the present invention. The perpendicular magnetization patterns are arranged at a distance of l ₁ and l ₂ as shown in the figure, and are XX
The distances l ₁ and l ₂ are set by the magnetic head scanning on the line, and Y
A magnetic head that scans on the -Y line encodes distance information (l ₁ → L ₁ , l ₂ → L ₂ ) and writes it on a track on the YY line.

FIG. 4 shows a control block diagram of the pattern coding apparatus of the present invention. In the figure, reference numeral 41 denotes a DC magnetizing head for scanning the XX axis shown in FIG. 3, reference numeral 42 denotes a forgery prevention pattern code reading head, which is mounted along the XX axis like the DC magnetizing head 41. .

An amplifier circuit 44 amplifies the forgery prevention pattern signal read by the read head 42. 45 is a rectifier circuit that passes only the signal of the positive component from the amplifier circuit 44, 46 is a Schmitt circuit that passes signals above a certain threshold, 47 is a monostable multivibrator, Schmitt circuit 46
The ON signal is transmitted by the set signal from. This ON signal continues to be sent until the OFF signal is received from the inverter circuit 412. 48 is a time delay circuit that delays the signal waveform from the monostable multivibrator 47 by a certain time τ ₁ , 49 is an AND gate circuit, and 410 is an amplifier circuit 44.
Rectifier circuit that passes only the signal of the negative component from
411 is a Schmitt circuit that passes a signal above a certain threshold, 412 is an inverter circuit that sends a reset signal to the monostable multivibrator 47, 413 is a rectifier circuit that passes only the signal of the positive component from the AND gate circuit 49, 414 Is the signal waveform from the rectifier circuit 413 for a certain time τ ₂
A time delay circuit for delaying by 415, a monostable multivibrator 415 which is set by the signal from the time delay circuit 414, and sends a steady signal until the reset signal from the counter circuit 423 is sent to the AND gate circuit 416, and 417 is a clock circuit , 418 is a counter circuit for counting the clock pulses from the clock circuit 417, and 419 is an AND gate 49.
Rectifier circuit that passes only the signal of the negative component from
An inverter circuit 420 sends a reset signal to the monostable multivibrator 415 and counter circuits 423 and 418. Here, the counter circuit 423 counts the signals from the time delay circuit 414, and sends out a reset signal to the monostable multivibrator 415 when the number of pulses becomes three.

Next, the operation of the pattern coding apparatus shown in FIG. 4 will be described with reference to the timing chart shown in FIG. The DC magnetizing head 41 and the read head 42 are X-type magnetic recording media.
It is arranged on the X-axis and is first DC magnetized by the DC magnetizing head 41, and then the pattern information is read by the read head 42.

After being magnetized by the DC magnetizing head 41, a pulse (i) in the positive direction is induced in the read head 42 if the read head 42 reaches the bill edge, and this signal is amplified by the amplifier circuit 44.
After that, the amplified signal a passes through the rectifier circuit 45 because it is a signal in the positive direction, but the Schmitt circuit 46 waveform-shapes only the pulse of a certain peak value and outputs the output signal b from the monostable multivibrator 47. After that, the time delay circuit 48 obtains the output signal c delayed by a constant time τ ₁ . Therefore, the plus gate pulse (i) output from the bill edge is removed from the AND gate circuit 49.

After that, the position where the vertical pattern is oriented is read head 41
Scans sequentially (ii), (iii), (iv), (v)
The waveform as shown by is output, and the waveform signal d is obtained via the rectifier circuit 413 and the time delay circuit 414. This waveform signal d
Sets the monostable multivibrator 415. Clock pulse CL while this output signal d is being output
K passes through the AND gate circuit 416 to obtain the output signal e. The output signal set due to the plus-direction pulse of the pulse waveform (ii) is reset by the minus-direction pulse of the pulse waveform (iii). That is, the output signal from the AND gate circuit 49 is rectified by the rectification circuit 419, only the minus of the signal a is passed, the signal is inverted by the inverter circuit 420, and the monostable multivibrator 41
5. Reset the counter circuit 418 and the counter circuit 423. When the counter circuit 418 is reset, the distance information is sent to the device connected to this circuit at that timing. L ₁ ′ and L ₂ ′ are vertical patterned regions I, respectively
It is the distance information of I, III and III, IV. Regarding the distance information between IV and V, the counter circuit 423 measures the output pulse d, and when the signal based on IV is counted, the counter circuit 423 sends a reset signal to the monostable multivibrator 415 (at the moment of setting). Counter circuit 418 does not count.

The example described above is a case where three vertically patterned regions (II, III, IV) are provided, but the present invention is not limited to this.

In the above description, the case of scanning only on the X-X axis has been described. Next, the case of scanning on the X-X axis and the Y-Y axis will be described with reference to FIG. FIG. 5 is a control block diagram of the pattern coding apparatus of the present invention. In the figure,
51 is a DC magnetizing head for scanning the XX axis shown in FIG.
Reference numeral 52 is an anti-counterfeit pattern code reading head, which is mounted along the XX axis like the DC magnetizing head 51. Reference numeral 53 is a write head for writing the information read by the read head 52, and is attached along the YY axis shown in FIG. 54 is an amplifier circuit that amplifies the anti-counterfeit pattern read by the read head, 55 is a rectifier circuit that allows only the positive component signal from the amplifier circuit 54 to pass, 56 is a Schmitt circuit that allows signals above a certain threshold to pass, and 57 is It is a monostable multivibrator, which sends an ON signal by the set signal of the Schmitt circuit 56 and continues to send it until an OFF signal is received from the inverter circuit 412. Reference numeral 58 is a time delay circuit that delays the signal waveform from the monostable multivibrator 57 by a certain time τ ₁ , 59 is an AND gate circuit, 510 is a rectifier circuit that allows passage of only the negative component signal from the amplifier circuit 54, 51
1 is a Schmitt circuit that passes signals above a certain threshold, 5
12 is an inverter circuit that sends a reset signal to the monostable multivibrator 57, and 513 is an AND gate circuit 5
Rectifier circuit that passes the signal of only the positive component from 9, 5
14 is a time delay circuit that delays the signal from the rectifier circuit 513 by the time τ ₂ for waveform, 515 is set by the signal from the time delay circuit 514, and the counter circuit 5 is set in the AND gate circuit 516.
Monostable multivibrator that sends reset signal from 23, 517 is clock circuit, 518 is clock circuit 51
A counter circuit that counts clock pulses from 7; 519, a rectifier circuit that passes only the negative component from the AND gate circuit 59; and 520, a monostable multivibrator 5
15, an inverter circuit that sends a reset signal to the counter circuits 523 and 518, 521 is a coding circuit that codes the count signal from the counter circuit 518, and 522 is an amplifier circuit. The counter circuit 523 counts the signals from the time delay circuit 514, and sends out a reset signal to the monostable multivibrator 515 when the number of pulses becomes three.

Next, regarding the operation of the pattern coding apparatus of FIG.
Description will be given according to the timing chart shown in FIG. The DC magnetizing head 51 and the read head 52 are arranged on the XX axis, and the magnetic recording medium is first DC magnetized by the DC magnetizing head 51, and then the pattern information is read by the read head 52.

If the read head 52 reaches the bill edge after being DC magnetized by the DC magnetizing head 51, a pulse (i) in the positive direction is induced in the read head 52, and the signal a is amplified by the amplifier circuit 54. After that, since this signal is a plus-direction signal, it passes through the rectifier circuit 55. The Schmitt circuit 56 waveform-shapes only a pulse having a certain peak value to obtain a signal output b from the monostable multivibrator 57, and then obtains an output signal c delayed by a certain time τ ₁ . Therefore, the pulse (i) in the plus direction output from the bill edge is removed from the AND gate circuit 59. After that, if the magnetizing head 52 scans the position in which the vertical pattern is oriented, it is sequentially (ii), (ii).
The waveforms shown in i), (iv), and (v) are output, and the waveform signal d is obtained via the rectifier circuit 513 and the time delay circuit 514. The same waveform signal d sets the monostable multivibrator 515. While this output signal is being output,
The clock pulse CLK passes through the AND gate circuit 516 to obtain the output signal e. The output signal set due to the plus-direction pulse of the pulse waveform (ii) is
It is reset by the negative pulse of i). That is, the output signal from the AND gate circuit 59 is the rectifier circuit 51.
The signal is rectified by 9 and only the minus of the signal a is passed, and the signal is inverted by the inverter circuit 520, and the monostable multivibrator 515, the counter circuit 518 and the counter circuit
Reset 523. When the counter circuit 518 is reset, the number of pulses counted so far is changed to the coding circuit 521.
And the coded signals L ₁ and L ₂ are output. The signals L ₁ and L ₂ are respectively generated in the vertically patterned regions II and I.
It is a coded signal according to the distance information of II, III, and IV.

For the distance information between the areas IV and V, the counter circuit 52
In order to send the reset signal from the counter circuit 523 to the monostable multivibrator 515 (to be reset at the moment when it is set), the counter circuit 523 counts the waveform signal d from 3 and counts the signal based on iV. 518 is not counted.

The coded signals L ₁ and L _{2 described above} are transmitted to the amplifier circuit 522.
Amplified by, write with write head 53, this head 53
Scans on the Y-Y axis shown in FIG. 3 to record the magnetization pattern (L ₁ , L ₂ ).

Next, a circuit for determining the authenticity of the magnetic recording medium according to the present invention will be described with reference to FIG. In the figure, 81 is a DC magnetizing head, 82 is a read head mounted on the XX axis in FIG. 3, 83 is a read head mounted on the YY axis in FIG. 3, and 84 is a read head 82. An amplifying circuit for amplifying the signal read by 1., 85 is a signal processing and coding circuit, which codes the distance information l ₁ , l ₂ shown in FIG. 3 read by the read head 82. Signal processing and coding circuit 85
Is a rectifying circuit 55 to a coding circuit 52 in the block diagram of FIG.
It is realized by the circuit shown in 1. 86 is an amplifier circuit for amplifying the information read by the read head 83, and 87 is Y shown in FIG.
A coding circuit for reading and coding the magnetic recording information L ₁ and L ₂ written on the Y axis, and 88 is distance information l ₁ and l ₂ read by the read head 82 and magnetic information read by the read head 83. It checks whether the recorded information L ₁ and L ₂ match, and if they match, sends a “true” signal to the circuit connected to this circuit, and if they do not match, connects to this circuit It is a true / false determination circuit that sends a "false" signal to the circuit.

As is clear from the above description, even if the information on the magnetic recording medium as shown in FIG. 3 is transferred, even if the information on the magnetic recording information L ₁ and L ₂ can be transferred, the distance information l ₁ and l ₂ Can be unique to the magnetic recording medium, so that it is possible to completely prevent forgery.

EFFECTS OF THE INVENTION According to the present invention described above, the region where the easy axis of magnetization of the magnetic material is arranged in the plane direction of the substrate and the easy axis of the magnetic material is in the direction perpendicular to the substrate or this arrangement. In a magnetic recording medium that is arranged at a certain angle with respect to the direction and has a plurality of regions in which this arrangement is disturbed, the distance between the regions in which the above arrangement is disturbed is measured by electrical means. The distance information is coded, the coded information is recorded in an area arranged in one horizontal direction of the magnetic body, and when the information is read from the magnetic recording medium, the read information and the distance information are combined. It is possible to provide a method for preventing forgery of a magnetic recording medium that compares and verifies, and determines that the bills are genuine if both match. According to this method, it is impossible to copy the recorded contents without using the one-layer magnetic recording medium without using the costly two-layer magnetic recording medium and further without coding the pattern. The effect of saying is obtained.

[Brief description of drawings]

FIG. 1 is a shape diagram of a magnetic recording medium according to an embodiment of the present invention, FIG. 2 is a diagram showing a detection output of a magnetic head, and FIG. 3 is a coded state of a forgery prevention pattern of the present invention. FIGS. 4, 5 and 6 are control block diagrams of the pattern coding apparatus of the present invention, FIG. 6 is a control time chart diagram of the pattern coding apparatus of the present invention, and FIG. 7 is a magnetic recording medium of the present invention. It is a truth discrimination circuit diagram. 11 ... Magnetic read head, 12 ... Detection coil, 13 ... Magnetic layer, 14,15 ... Region, 16 ... Substrate, 41,51 ... DC magnetizing head, 42, 52 ... Read head, 53 ... … Write head, 44,54
…… Amplifier circuit, 45,55 …… Rectifier circuit, 46,56 …… Schmidt circuit, 47,57 …… Monostable multivibrator, 48,58 …… Time delay circuit, 49,59 …… And gate circuit, 410,510 …… Rectifier circuit, 411,511 …… Schmidt circuit, 412,512 …… Inverter circuit, 413,513 …… Rectifier circuit, 414,514 …… Time delay circuit, 415,515 …… Monostable multivibrator, 417,517 …… Clock circuit, 4
18,518 …… Counter circuit, 419,519 …… Rectifier circuit, 420,5
20 …… Inverter circuit, 521 …… Coding circuit, 522 ……
Amplification circuit, 423, 523 ... Counter circuit.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Hideo Urata Inventor Hideo Urata 1-1-1, Wadasaki-cho, Hyogo-ku, Kobe-shi, Hyogo Mitsubishi Heavy Industries, Ltd. Kobe Shipyard (72) Inventor Masayasu Suzuki Muneba, Shizuoka-shi, Shizuoka 3-1, Machikawa, Ltd., Technical Research Laboratory, Tomoegawa Paper Co., Ltd. (56) References Japanese Patent Laid-Open No. 61-77102 (JP, A) Actual No. 57-204526 (JP, U)

Claims (1)

[Claims] 1. A region in which the easy axis of magnetization of a magnetic material is arranged in the plane direction of a substrate, and the easy axis of magnetization of the magnetic material is perpendicular to the substrate or forms a constant angle with respect to this arrangement direction. In a magnetic recording medium in which a plurality of regions are arranged in an array and the array is disturbed, the distance between the regions in which the array is disturbed is measured by electrical means, and this distance information is coded. The encoded information is recorded in an area arranged in one horizontal direction of the magnetic material, and when the information is read from the magnetic recording medium, the read information and the distance information are compared and collated, and both are coincident. For example, a method for preventing forgery of a magnetic recording medium, which is characterized by determining that the bill is genuine.