JP3940612B2 - Magnetic card analyzer and analysis method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a magnetic card analysis apparatus and analysis method for identifying features unique to a magnetic card encoder that has written magnetic recording data based on a magnetic recording signal of the magnetic card to which magnetic recording data has been written.
[0002]
[Prior art]
In recent years, magnetic cards such as credit cards, telephone cards, transportation commuter passes and boarding cards have become widespread, and along with this, crimes using forged magnetic cards have increased. In this case, even if the suspect is arrested and the counterfeit magnetic card can be seized, the roots of the counterfeit magnetic card must be relied on the suspect's confession. I can't.
[0003]
Therefore, even if crimes by the same criminal organization are repeated, it is only possible to arrest the suspect who did the criminal act at the time the crime was discovered, and to obtain important clues to locate and destroy the criminal organization It was extremely difficult.
[0004]
Here, if it is possible to specify which manufacturer's magnetic card encoder issued the counterfeit magnetic card that was seized or used, the crime that issued the counterfeit magnetic card that was previously seized This is a powerful clue for determining whether or not there is a connection with the organization and for identifying the criminal organization from the purchaser of the magnetic card encoder.
[0005]
[Problems to be solved by the invention]
However, when the magnetic recording data is recorded by frequency modulation, the magnetic flux is “0” if there is a magnetic flux reversal at an interval equal to the magnetic flux reversal interval of the clock signal, and the magnetic flux is ½ the magnetic flux reversal interval of the clock signal. If there is inversion, it is recorded according to the standard of “1”, and the magnetic card encoders of any manufacturer have substantially the same magnetic flux inversion interval of the clock signal. Also, the magnetic field strength may change gradually during use even though it is almost equal in the initial state. Therefore, it is often impossible to specify the magnetic card encoder only by comparing the magnetic flux reversal interval and the magnetic field strength.
[0006]
For this reason, as a result of various studies, the inventor has written the same data on the magnetic card, but magnetic cards issued from the same magnetic card encoder have the same characteristics based on the characteristics of the magnetic card encoder. It was discovered that magnetic cards issued from different types of magnetic card encoders have different characteristics.
[0007]
That is, the magnetic pulse waveform is ideally a rectangular wave, but in reality, the rise and fall are dull and waveform distortion occurs. This waveform distortion depends on the magnetic head material, shape, mounting position, applied voltage, and the characteristics of each part used in the drive circuit. Waveform distortion will be different if different parts are used.
[0008]
Therefore, the waveform distortion can be said to be a fingerprint or a voiceprint of the magnetic card encoder, and appears regardless of the difference in data contents written in the magnetic card even if the magnetic flux reversal interval and the magnetic field strength are equal. For this reason, when a counterfeit magnetic card is seized, etc., it is possible to identify whether or not there is a connection with a criminal organization that previously issued a counterfeit magnetic card, and which manufacturer's model is a magnetic card issued It becomes a clue.
[0009]
Therefore, the present invention has a technical problem to identify the characteristics of the magnetic card encoder that has written the magnetic recording data from the magnetic recording signal of the magnetic card based on the knowledge of the inventors.
[0010]
[Means for Solving the Problems]
In order to solve this problem, the present invention provides a magnetic card analyzer for identifying features unique to a magnetic card encoder that has written magnetic recording data based on a magnetic recording signal of the magnetic card to which magnetic recording data has been written. A waveform reading means for reading a magnetic pulse waveform representing a change in magnetic field strength with respect to the longitudinal direction of the magnetic recording portion from a magnetic flux reversal signal recorded on the magnetic card, and a rise time and a fall time of the read magnetic pulse waveform. The present invention is characterized by comprising waveform distortion detecting means for detecting waveform distortion based on this and comparison means for comparing the detected waveform distortion with the waveform distortion of another magnetic card stored in advance .
[0011]
According to the present invention, a magnetic pulse waveform representing a change in magnetic field strength with respect to the longitudinal direction of the magnetic recording portion is read from the magnetic flux reversal signal recorded on the magnetic card, and waveform distortion is generated based on the rise time and fall time. It is detected by the strain detection means. Therefore, if the waveform distortion characteristics data of the magnetic card encoder sold by each manufacturer is known in advance, the magnetic card is issued from which manufacturer's model of the magnetic card encoder by comparing these data. Can be specified.
[0012]
In addition, since it has a comparison means for comparing the detected waveform distortion with the waveform distortion of another magnetic card stored in advance, whether two magnetic cards are issued from the same magnetic card encoder You can determine whether or not.
[0013]
The waveform distortion is determined based on the rise time and fall time of the read magnetic pulse waveform, and if it is detected as numerical data as in the invention of claim 3 , data processing is extremely easy. Comparison and collation are also simplified. As this numerical data, for example, as in the invention of claim 4 , the rise time until the magnetic field intensity reaches a positive or negative peak value from 0 and the fall time until the peak value reaches 0 are used. be able to. In the present specification, the term “rise time” and “fall time” are not limited to strictly time, but the “rise part” of the magnetic pulse waveform representing the change in magnetic field strength in the longitudinal direction of the magnetic recording part. The concept also includes “length” and “length of falling portion”. When the magnetic card is run at a constant speed and the magnetic pulse waveform is read, or when the clock pulse corresponding to the moving distance of the magnetic card is output by the roller that rolls in contact with the magnetic card, the "rise time" This is because the “down time”, “length of the rising portion”, and “length of the falling portion” are uniquely determined.
[0014]
In the invention of claim 5 , the waveform distortion is detected from the magnetic pulse waveform of the clock signal recorded before the start code or after the end code of the magnetic recording data. Arbitrary “0” and “1” data are randomly recorded in the magnetic data recording section from the start code to the end code of the magnetic card, so that it is difficult to compare the data. After that, a clock signal having a magnetic flux reversal interval equal to “0” is recorded on any magnetic card. Therefore, if the waveform distortion is detected from the magnetic pulse waveform in this portion, the waveform distortion can be accurately compared regardless of the contents of the magnetic recording data.
[0015]
In the invention of claim 6 , the waveform distortion is determined by statistically processing values detected from the magnetic pulse waveforms of a plurality of clock signals. The degree of variation in waveform distortion can be determined by obtaining the variance of the waveform distortion values measured for a plurality of clock signals recorded on the same magnetic card.
[0016]
If the variance is close to 0, there is no variation in the waveform distortion, and the same waveform distortion is generated for all measured time signals, so that it can be determined that these are waveform distortions caused by the characteristics of the magnetic card encoder. Also, the greater the variance, the more the waveform distortion varies, and different waveform distortions occur for each clock signal, so it is determined that these include waveform distortions that do not originate from the characteristics of the magnetic card encoder. it can. Therefore, in such a case, if the waveform distortion whose variance is close to 0 is detected by changing a plurality of clock signals as detection targets, only the waveform distortion caused by the characteristics of the magnetic card encoder can be detected. Will improve.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be specifically described below with reference to the drawings. 1 is a schematic explanatory view showing an example of a magnetic card analyzer according to the present invention, FIG. 2 is a graph showing a magnetic pulse waveform, FIG. 3 is a flowchart showing a processing procedure of waveform distortion detecting means, and FIG. 4 is a plurality of pulse waveforms. It is a graph which shows the case where it overlaps and compares.
[0018]
The magnetic card analyzer 1 of this example is for identifying features unique to the magnetic card encoder that has written the magnetic recording data based on the magnetic recording signal of the magnetic card 2 to which the magnetic recording data has been written by the frequency modulation method. There is a magnetic card reader (waveform reading means) 3 for reading the magnetic flux reversal signal recorded in the magnetic recording section 2a of the magnetic card 2 and outputting the magnetic pulse waveform, and preset based on the outputted magnetic pulse waveform. A personal computer 4 that performs predetermined data processing based on the program.
[0019]
The magnetic card reader 3 includes a magnetic head 6 disposed in a slit 5 through which the magnetic card 2 is inserted. Based on a magnetic flux reversal signal read by the magnetic head 6, the magnetic card reader 3 extends in the longitudinal direction of the magnetic recording unit 2 a of the card 2. A magnetic pulse waveform (see FIG. 2) representing a change in magnetic field strength is output.
[0020]
When the magnetic pulse waveform is input, the personal computer 4 compares the measured waveform distortion with the waveform distortion of another magnetic card stored in advance, and the waveform distortion detecting means 7 for detecting the waveform distortion of the magnetic pulse waveform. Comparing means 8 is provided.
[0021]
FIG. 3 is a flowchart showing the data processing procedure of the waveform distortion detection means 7. First, when a magnetic pulse waveform is input in step STP1, the process proceeds to step STP2, where the code before or after the start code of the magnetic recording data. Magnetic pulse waveforms of eight clock signals recorded later are arbitrarily selected. Then, the processing proceeds to step STP3, the eight individual pulses, the rise time T ₁ of the field strength represented by the alternating-current voltage waveform from 0 (V) positive peak voltage value (peak value) up to P, detecting a fall time T ₂ of the from the peak voltage value P down to 0 (V).
[0022]
In step STP4, based on the eight of the detected rise time for the pulse T ₁ and fall time T _2, and calculates the variance and the average rise time A ₁ and the average falling time A _2, the average ratio A ₁ / a ₂ is calculated as the characteristic value of the waveform distortion.
[0023]
In step STP5, these values and the averaged one pulse waveform are displayed on the display device 9. Here, if the variance is 0, it can be seen that there is no variation in the waveform distortion of the detected eight pulses, and an equal waveform distortion has occurred. Since these can be estimated to be waveform distortion caused only by the characteristics of the magnetic card encoder, the characteristic value of the waveform distortion and one averaged pulse waveform are stored in a predetermined recording area.
[0024]
Then, the process proceeds to step STP6, and by comparing with the characteristic value of the waveform distortion of the magnetic card issued by the magnetic card encoder of each model of each manufacturer stored in advance, which model of which manufacturer the magnetic card is It can be immediately discriminated whether it was issued by the magnetic card encoder.
[0025]
If the variance calculated in step STP5 is not 0, it can be determined that waveform distortion due to an external factor unrelated to the characteristics of the magnetic card encoder has occurred in the detected eight pulses. Therefore, since the magnetic card encoder cannot be specified by the waveform distortion characteristic value based on such an average value, the processing is interrupted, the magnetic card 2 is read again, and the same processing is performed based on eight different pulses. It is sufficient to use only waveform distortion data with a variance of zero.
[0026]
Furthermore, if the variance does not become zero after repeated, it can be determined that the signal is issued by a magnetic card encoder that cannot accurately clock the clock signal. Can be a clue.
[0027]
The comparison means 8 for comparing the magnetostrictions of the plurality of magnetic cards 2 detects the magnetostriction for each magnetic card 2 by the magnetostriction detection means 7 described above, and stores the data when the variance is 0. Place, as shown in FIG. 4, the display graph superimposed leverage these pulse waveforms to match the position of the peak voltage value, the magnetic flux inversion interval a _{1 +} a 2 _each, the average rise time a _1, the average falling The time A ₂ , the waveform distortion characteristic value A ₁ / A ₂ , and the variance σ are displayed in a list. As a result, a magnetic card issued by the same magnetic card encoder can be easily identified from among a plurality of magnetic cards.
[0028]
In FIG. 4, magnetic pulse waveforms detected for two magnetic cards issued by different magnetic card encoders are displayed in an overlapping manner. In this example, the average magnetic flux reversal interval (A ₁ + A ₂ ) of each magnetic pulse waveform S ₁ and S ₂ is 610 μs, but the average rise time A ₁ = 260 μs of the magnetic pulse waveform S ₁ is average whereas a fall time _a 2 = 350 _μs, magnetic pulse waveform _{S 2} is _a 1 = 290 _μs, because it is a 2 = 320 μs, each characteristic value of the waveform distortion 0. 743,0. 906 next The values are completely different.
[0029]
Since each magnetic card has a different waveform distortion characteristic value, it can be seen that the magnetic cards were issued by different magnetic card encoders. If each magnetic card encoder has the characteristic value of the waveform distortion of the issued magnetic card as data in advance, the magnetic card encoder can be specified by comparing the characteristic values of the waveform distortion.
[0030]
In the above description, the magnetic card reader 3 reads the magnetic card 2 to obtain a magnetic pulse waveform. For example, the magnetic pulse waveform of the magnetic card 2 is applied to a terminal device using the magnetic card 2. If stored, the waveform distortion can be detected based on the waveform signal without the magnetic card 2.
[0031]
【The invention's effect】
As described above, according to the present invention, the waveform distortion based on the characteristics of the magnetic card encoder that issued the magnetic card is generated based on the magnetic pulse waveform representing the change in the magnetic field strength with respect to the longitudinal direction of the magnetic recording portion of the magnetic card. By detecting the waveform distortion data, it is possible to determine whether or not there is a connection with the criminal organization that issued the counterfeit magnetic card that was seized before, or from the purchaser of the magnetic card encoder. There is an excellent effect that it is possible to provide powerful clues for specifying an organization.
[Brief description of the drawings]
FIG. 1 is a schematic explanatory view showing an example of a magnetic card analyzer according to the present invention.
FIG. 2 is a graph showing a magnetic pulse waveform.
FIG. 3 is a flowchart showing a processing procedure of waveform distortion detection means.
FIG. 4 is a graph showing a case where a plurality of pulse waveforms are overlaid and compared.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Magnetic card analyzer 2 ... Magnetic card 2a ... Magnetic recording part 3 ... Magnetic card reader (waveform reading means)
7 ............ Waveform distortion detection means 8 ...... Comparison means P ............ Peak voltage value (peak value)
T ₁ .... Rise time T ₂ ..... Fall time

Claims (7)

A magnetic card analyzer for identifying features unique to the magnetic card encoder that has written the magnetic recording data based on the magnetic recording signal of the magnetic card (2) to which the magnetic recording data has been written,
A waveform reading means (3) for reading a magnetic pulse waveform representing a change in magnetic field strength with respect to the longitudinal direction of the magnetic recording section (2a) from a magnetic flux reversal signal recorded on the magnetic card (2);
Waveform distortion detection means for detecting a wave Katachiibitsu based on the rise and fall times of the read magnetic pulse waveform (7),
A magnetic card analyzer comprising comparison means (8) for comparing the detected waveform distortion with the waveform distortion of another magnetic card stored in advance . A magnetic card analyzer for identifying features unique to the magnetic card encoder that has written the magnetic recording data based on the magnetic recording signal of the magnetic card (2) to which the magnetic recording data has been written,
When the magnetic pulse waveform representing the magnetic field intensity changes with respect to the longitudinal direction of the magnetic recording portion of the magnetic card (2) (2a) is inputted, detecting the waves Katachiibitsu based on the rise time and fall time of the magnetic pulse waveform Waveform distortion detecting means (7) for
A magnetic card analyzer comprising comparison means (8) for comparing the detected waveform distortion with the waveform distortion of another magnetic card stored in advance . 3. The magnetic card data analyzing apparatus according to claim 1, wherein the waveform distortion detecting means (7) detects the waveform distortion as numerical data. The waveform distortion detecting means (7) changes the waveform distortion from 0 to a rise time (T ₁ ) until the magnetic field intensity reaches 0 to a positive or negative peak value (P). The magnetic card analyzer according to any one of claims 1 to 3, wherein the magnetic card analyzer is configured to detect based on a fall time (T ₂ ). The waveform distortion detecting means (7) is, according to any one of the magnetic pulse waveform before the start code of the magnetic recording data or end clocking signal recorded after the sign of the claims 1 to 4 for detecting the waveform distortion Magnetic card analyzer. The waveform distortion detecting means (7) detects a numerical value that becomes waveform distortion from magnetic pulse waveforms of a plurality of clock signals recorded before or after the start code of the magnetic recording data, and statistically processes the value. The magnetic card analyzer according to claim 1, wherein the waveform distortion is determined by A magnetic card analysis method for identifying characteristics unique to a magnetic card encoder that has written magnetic recording data based on a magnetic recording signal of the magnetic card (2) to which magnetic recording data has been written,
The waveform distortion is detected based on the rise time and fall time of the magnetic pulse waveform representing the change in the magnetic field strength with respect to the longitudinal direction of the magnetic recording portion (2a) of the magnetic card (2), and the waveform distortion is detected in advance. A magnetic card analysis method comprising comparing or collating with a waveform distortion of a magnetic card.

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