JP3121153B2 - Method for correcting output waveform and method for determining authenticity of information recording medium using identification information thereof - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the identification of an information recording medium such as a prepaid card using a base material in which conductive materials are mixed at random by the distribution of the conductive material in the medium. The present invention also relates to a method for correcting an output waveform used as information for identification and a method for determining the authenticity of an information recording medium using the identification information.

[0002]

2. Description of the Related Art Credit cards, cash cards,
In the case of a card-shaped information recording medium such as an identification card or a telephone card, the information recording medium must be a genuine information recording medium in order to prevent unauthorized use, forgery, and tampering of the information recording medium. Identification information for recognition is provided.

As an information recording medium suitable for such a purpose, fine metal fibers made of a conductor are randomly dispersed as identification information in a base material of an information recording medium made of paper, synthetic paper or synthetic resin. Are known (for example, Japanese Patent Application Laid-Open No. 50-69999,
-108172, JP-A-3-27489, etc.).

In this conventional technique, identification of an information recording medium is obtained by emitting a microwave to a predetermined area when the medium is used, and reading the reflected wave of the metal fiber using a microwave sensor to read the distribution of the metal fiber. The identification information is compared with the identification information previously read by the microwave sensor in the area when the medium is issued, and when the identification information matches within a certain reference value, the medium is determined to be authentic. And
The information recording medium is being identified. The information for identification is provided on the information recording medium as described above, and the identification information obtained by reading the area with a microwave sensor when the medium is issued is recorded on the magnetic recording layer in advance.

[0005]

The characteristics of the information recording medium provided with the above-mentioned metal fiber are that the distribution of the metal fiber is random, so that it is difficult to forge the base material itself. It does not exist.

Therefore, when these conventional techniques are used for the above-mentioned card-shaped information recording medium (hereinafter, referred to as a card), extremely high security can be obtained.

However, such a card has a structure in which a plurality of layers having different properties such as a magnetic recording layer, a concealing layer, and a protective layer are laminated on a base material made of a single or laminated body of paper, synthetic paper or synthetic resin. Therefore, the card itself naturally has some warping, bending, twisting and bending (hereinafter referred to as "warping"), and also has a warping depending on the storage condition of the card user.

When a card having such a warp is read by a sensor according to a conventional method and the distribution of the conductive material is read as a reflected wave, an output waveform thereof corresponds to a warp of the card in a signal waveform unique to the card. It becomes a waveform in which the waveform components overlap.

Therefore, the output waveform obtained from the card at this time is different from the information recorded on the magnetic recording layer in order to identify the card when the card is issued.
In spite of being a genuine card, it is determined that the card is forged or falsified.

At this time, if the card is mechanically held in the card information reading device so as to eliminate the warpage of the card, such a determination result will not be obtained, but the mechanical reading is actually performed in the card information reading device. It is difficult to hold the card flat at the same time, and it must be affected by a certain amount of warping.

Further, even if a mechanism for mechanically holding the card flat is provided, the internal mechanism of the information reading device becomes complicated, and the cost of the information reading device increases, and the system using the above-mentioned authenticity determination method is increased. Will hinder the spread of

[0012]

According to the present invention, in an information recording medium using a base material on which a randomly distributed conductive material is mixed, the randomly distributed conductive material is used for identifying information of the information recording medium. And a frequency analysis of an output waveform obtained by reading a randomly distributed conductive material with a sensor, and correcting the output waveform by removing low frequency components below a predetermined frequency. Is provided. In addition, by using the identification information generated by the correction method, in an information recording medium using a base material in which conductive materials randomly distributed are mixed, the information recording medium includes an information recording layer, and information recording is performed in advance. The conductive material randomly distributed in the information recording layer of the medium is recorded as medium information of the information recording medium, and the conductive material randomly distributed is subjected to frequency analysis of an output waveform obtained by reading with a sensor, and a predetermined frequency or less. An information recording medium for correcting an output waveform by removing a low frequency component, and comparing medium information recorded on an information recording layer of the information recording medium with identification information after the output signal is corrected. Is provided.

That is, according to the output waveform correction method of the present invention, the output waveform obtained by reading the distribution of the conductive material mixed in the base material of the information recording medium with the sensor is subjected to frequency analysis, and the information recording medium is warped. By reproducing the identification information by removing the low frequency components corresponding to the waveform components of the above, it is possible to obtain the identification information that does not depend on the warpage of the information recording medium, and it is possible to significantly improve the accuracy of the identification of the information recording medium. It becomes possible.

According to the method of the present invention for determining the authenticity of an information recording medium using the identification information corrected by the correction method, the distribution of the conductive material mixed in the base material of the information recording medium is read by a sensor. The frequency of the output waveform is analyzed, and the identification information reproduced by removing the low frequency component corresponding to the waveform component of the warpage of the information recording medium is compared with the medium information recorded in the information recording layer of the information recording medium in advance. Since the authenticity is determined, the accuracy of identification of the information recording medium can be significantly improved, and the forged or falsified information recording medium can be easily identified.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a correcting means for removing a low frequency component corresponding to a warp component of an information recording medium according to the present invention will be described below.

In this embodiment, a metal fiber is used as the conductive material randomly distributed in the base material of the information recording medium, and a microwave sensor is used as a sensor for reading the metal fiber.

One of effective means for removing a low frequency component corresponding to a warp component of an information recording medium is obtained by digitally converting (A / D converting) an output waveform read by a microwave sensor. This is to remove the low-frequency component corresponding to the warpage of the information recording medium by developing the signal obtained by Fourier series or performing frequency analysis by a method such as Fourier transform.

The following equations 1 to 4 are relational expressions when the output waveform read by the microwave sensor is expanded by a Fourier series, assuming that the output waveform is a function of a repetitive and continuous cycle.

[0019]

(Equation 1)

[0020]

(Equation 2)

[0021]

(Equation 3)

[0022]

(Equation 4) (Where f is the output waveform, t is time, ω is the fundamental angular frequency,
T is the period and n is the order. ) Removal of low frequency components
Waveform components An and Bn having small values of order (n) in the above equation
You only have to remove. This is because when the frequency component of the warpage of the information recording medium itself is compared with the frequency component due to the distribution of the metal fibers, the frequency component of the warpage of the information recording medium itself has a lower frequency, and the value of the order (n) in the above equation Can remove the frequency components corresponding to the warpage of the information recording medium itself, except for the waveform components An and Bn corresponding to n = 2.

By performing the processing of the output waveform in this manner, even if the information recording medium is warped, the distribution of the metal fibers can be read by using a conventional information reading device having a built-in microwave sensor. It is possible to easily obtain identification information that does not depend on the warpage of the information recording medium.

Therefore, the accuracy of the collation in the authenticity determination of the information recording medium is improved, and the security of the information recording medium against forgery and tampering is higher.

Next, an embodiment in a case where the method for determining the authenticity of an information recording medium of the present invention is applied to a card will be described below with reference to the drawings.

In FIG. 1, a card denoted by reference numeral 1 has a structure in which a magnetic recording layer 3, a concealing layer 4 and a protective layer 5 are laminated on one surface of a substrate 2, and the substrate 2 has Fine metal fibers are mixed.

As such a base material 2, a metal fiber of an appropriate length is mixed in a resin such as polyester, polypropylene, polycarbonate, polyethylene, polyvinyl chloride, polyimide, polyvinylidene chloride or the like, and this is generally known. It is obtained by molding into a film or sheet by a known method.

The substrate 2 thus obtained has metal fibers randomly distributed in the resin, and this distribution differs for each card.

For the magnetic recording layer 3, a generally known magnetic recording material can be used.

Next, with respect to the card 1 shown in FIG. 1, a method for issuing a card using the apparatus shown in FIG.

In FIG. 2, reference numeral 11 denotes a microwave sensor for reading a predetermined area of the card 1 when the authenticity of the card 1 is determined. Reference numeral 12 denotes a magnetic sensor on which information on the authenticity of the card (medium information) is recorded. The magnetic head reads the track T.

The output waveform of the microwave sensor 11 is A /
After being converted into a digital signal by the D converter 13, it is input to the frequency analysis circuit 14. This frequency analysis circuit 14
Expands the input signal with the above-described Fourier series, and obtains each frequency component up to n (order) of a sufficient magnitude.

The output of the frequency analyzing circuit 14 is supplied to a waveform synthesizing circuit 16 after a low frequency component caused by the warpage of the card is removed by the next filter 15. The waveform synthesizing circuit 16 has a function of synthesizing waveforms on the time axis based on the signals of the respective frequency components supplied from the filter 15. Is input to the input terminal.

On the other hand, on the magnetic track T of this card,
Medium information (magnetic signal) corresponding to the output waveform of the microwave sensor 11 obtained in advance (or having undergone correction processing) without warpage is recorded.

This magnetic signal is read by the magnetic head 12 and the obtained signal is demodulated by the demodulation circuit 17.
The other input terminal of the comparison circuit 18 is input as medium information.

The comparison circuit 18 uses the two inputs (identification information obtained by correcting the waveform read from the card by the microwave sensor 11) and a magnetic signal recorded in advance on the magnetic recording layer of the card by the demodulation circuit 17. The similarity of the demodulated media information) is compared, and if the correlation coefficient is equal to or more than a certain reference, the card 1 is determined to be positive. It judges that the card 1 is not authentic and outputs a judgment output.

FIG. 3 (a) shows a force waveform obtained by simply reading a warped card by the microwave sensor 11, and FIG.
The output waveform read at 1 is shown in FIG.

Usually, the criterion for this type of correlation coefficient is about 0.5.
The correlation coefficient between the two is about 0.72, which is a genuine card.
It is determined to be "false".

The reference for the correlation coefficient can be arbitrarily set depending on the type of information to be compared and the accuracy of the reading device.

FIGS. 3 (c) and 3 (d) show output waveforms from FIGS. 3 (a) and 3 (b), respectively.
With the apparatus shown in FIG. 2, n (order) =
The figure shows the identification information synthesized by the waveform synthesis circuit 16 after obtaining the frequency components 1 to 16 and removing the low frequency components corresponding to n = 1.

The correlation coefficient of the waveforms shown in FIGS. 3C and 3D is about 0.92, and the card is determined to be "true" according to the above-described criteria. Is done.

In the method of determining the authenticity of an information recording medium using the identification information obtained by the above-described method of correcting the output waveform, in the embodiment in which the correlation coefficient was obtained, the above-mentioned low frequency component was removed. Subsequently, the comparison result of the identification information synthesized by the waveform synthesis circuit 16 and the medium information obtained by demodulating the magnetic signal read from the magnetic track T by the magnetic head 12 by the demodulation circuit 17 is also shown in FIGS. The description is omitted because it is the same as d).

In the above-described embodiment, the case where the output waveform of the microwave sensor obtained without warping is recorded as it is on the magnetic track T in the form of each component on the time axis has been described. It is also possible to record with a signal (waveform) indicating the level of each frequency, which is the output of. However, in this case, at the time of authenticity determination, waveform synthesis is performed based on the magnetic signal reproduced from the magnetic recording layer 3, and the synthesized waveform is input to the comparison circuit 18 to determine the authenticity.

[0044]

As described above, according to the present invention, in an information recording medium in which conductive materials are mixed at random, a conductive material which is randomly distributed is used as identification information of the information recording medium. Analyze the frequency of the output waveform obtained by reading the conductive material distributed in the sensor,
Since the output waveform is corrected by removing a low frequency component below a predetermined frequency, the identification information of the warped information recording medium can be accurately read. Since the determination is performed, accurate true / false determination can be performed even for a warped card, and the safety and reliability of the information recording medium are greatly improved.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional view of an example of a card in which an output waveform is corrected according to the method of the present invention and the authenticity is determined based on the corrected identification information.

FIG. 2 is a block diagram of an apparatus for performing a true / false judgment according to the method of the present invention.

FIGS. 3A and 3B show output waveforms of a microwave sensor, wherein FIGS. 3A and 3C show a warped card, FIG. 3B shows a warped card, and FIG. 3D shows a correction method according to the present invention. It is an output waveform from which a component corresponding to warpage has been removed.

[Description of Signs] 1 Card 2 Base material 3 Magnetic recording layer 4 Hiding layer 5 Protective layer 11 Microwave sensor 12 Magnetic head 13 A / D converter 14 Frequency analysis circuit 15 Filter 16 Waveform synthesis circuit 17 Demodulation circuit 18 Comparison circuit

Continuation of the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) G06K 17/00 B42D 15/10 501 G06K 7/08

Claims (4)

(57) [Claims] 1. An information recording medium using a base material on which a randomly distributed conductive material is mixed, wherein the randomly distributed conductive material is used as identification information of the information recording medium, and the random distribution is performed. Performing a frequency analysis of an output waveform obtained by reading the conductive material with a sensor, and correcting the output waveform by removing low-frequency components below a predetermined frequency. 2. The method according to claim 1, wherein the frequency analysis uses Fourier series expansion. 3. An information recording medium using a base material in which conductive materials distributed at random are mixed, wherein the information recording medium includes an information recording layer, and the information recording layer of the information recording medium has a random number. The conductive material distributed in the medium is recorded as medium information of the information recording medium, and a frequency analysis of an output waveform obtained by reading the conductive material randomly distributed by a sensor is performed. And correcting the output waveform by comparing the medium information recorded on the information recording layer of the information recording medium with the corrected identification information of the output waveform. A method for determining the authenticity of an information recording medium. 4. The method according to claim 3, wherein the information recording layer of the information recording medium is a magnetic recording layer.