JP3499054B2 - Authenticity determination device for safety paper - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a genuine / counterfeit determination device for security paper such as securities, which requires authenticity prevention.

[0002]

2. Description of the Related Art In a safety protection paper prepared by embedding a safety wire made of a ferromagnetic material in a sheet to prevent forgery, it is practical to write data on the safety wire in order to improve safety assurance. It is being converted. In addition, a material having unique magnetic properties may be used in order to enhance safety. (JP-A-7-327 filed by the same applicant as the present application)
(See No. 78 “Safety protection paper and its authenticity determination device”)

[0003]

It has been found that the structure utilizing the unique magnetic characteristics of the material is extremely effective in terms of safety measures. However, in the conventional authenticity determination device shown in FIG. 10, since the exciting coil 3 excited by the exciting power supply 2 is used as the exciting magnetic field applying means and the magnetic head is used as the magnetic sensor 4, the exciting coil 3 is excited. Even if the magnetic field does not exist in the magnetic body 1 to be measured, there is a drawback that the S / N ratio deteriorates when the magnetic field enters the magnetic sensor 4 and the change in magnetic flux density of the magnetic body 1 to be measured is minute. Reference numeral 5 is an amplifier that amplifies the output from the magnetic sensor 4 and extracts a detection signal. Further, depending on the material, there is a drawback that the magnetic anisotropy greatly depends on the direction of the exciting magnetic field and the magnetic characteristics can be detected only in a fixed direction. For the convenience of inserting the magnetic thread used for the safety wire into the safety paper, generally, the thinner the magnetic thread is, the less uncomfortable the safety paper is, which is preferable. In this case, a highly sensitive magnetic sensor is required to detect the magnetic characteristics of an extremely thin magnetic material used as a safety wire. Further, the authenticity determination device is preferably inexpensive, and it is more economically advantageous if the data detection magnetic sensor and the magnetic characteristic detection magnetic sensor can be used in common.

It is an object of the present invention to detect the characteristics of a safety protection sheet economically and reliably even if the safety protection sheet is made of an extremely thin magnetic material and is embedded in the safety protection sheet. An object of the present invention is to provide an authenticity determination device for safety protection paper that can make a determination.

[0005]

In order to solve this object, the present invention uses a magnetic sensor having a structure in which an exciting coil, a magnetic flux detecting coil and a compensating coil are integrated as data and magnetic characteristic detecting means. , And a comparison circuit for comparing predetermined safety line information and magnetic characteristics. That is, the security according to the present invention
The authenticity determination device for paper protectors uses an exciting magnetic field whose magnetic field strength changes.
Made of a ferromagnetic material that exhibits unique magnetic hysteresis characteristics
So that the magnetic flux density changes with an externally applied magnetic field.
Have meaningful retention information in the processed part of the ferromagnetic material
We handle safety protection paper with embedded safety wires
The target is the excitation coil, the magnetic flux detection coil, and the compensation coil.
And a magnetic sensor having a structure in which
Strong magnetic force forming the safety wire detected by the sensor
The magnetic sensor is used to detect the hysteresis characteristics of the magnetic material.
Waveform distortion analysis result of the detected waveform and the genuine safety line
Detected in advance corresponding to the unique magnetic history characteristics
Waveform distortion analysis results of the waveform are properly matched, and
The sensors read out simultaneously from the safety line by the sensor.
The above-mentioned meaning that the information held is predetermined for the safety line
The security paper is authentic when it matches the stored information.
It is determined that there is a detection waveform corresponding to the magnetic history characteristics.
About the agreement about the waveform analysis result and the retention information
If you don't get a match, you can judge that it is a forgery.
And a determination means configured as described above.
The determination means is for measuring the harmonics included in the detected waveform.
Waveform distortion analysis result of the detected waveform depending on the level of a predetermined component
Can be configured to obtain

[0006]

With the apparatus of the present invention as described above, the authenticity of the safety protection sheet can be surely executed even when the safety line has an abnormal state such as a crack.

[0007]

Embodiments of the present invention will be described below. First, the principle of the magnetic sensor with a compensation coil used in the present invention,
The structure and operation will be described with reference to FIGS. The magnetization characteristic of a ferromagnetic material is expressed as follows.

## EQU00001 ## B = .mu.H (1) B: magnetic flux density, H: magnetic field strength, .mu .: permeability, .mu., However, is generally not linear but has a non-linear characteristic peculiar to a magnetic material.

This characteristic is obtained by measuring the magnetic flux density while changing the strength of the magnetic field. When measuring the magnetic properties of extremely thin (thickness of 1 μm or less) magnetic tape, magnetic tape thinly coated with magnetic material, magnetic ink, etc., it is difficult to measure because the magnetization of the magnetic material in this case is extremely small. is there. Expression (1) can be rewritten as Expression (2) below.

[Equation 2] B = μ ₀ H + J (2) H: strength of magnetic field, J: strength of change of magnetic substance, μ ₀ :
Vacuum permeability Here, μ ₀ is extremely small, so that B≈J can be set.

The voltage e detected by the detection coil is

[Equation 3] e = -dφ / dt (3) φ: Magnetic flux penetrating the detection coil

Since φ = ∫Jdv (4), it can be seen that the detection voltage from the magnetic substance having a minute volume dv is extremely small.

On the other hand, as shown in FIG. 1, a voltage V _e generated in the detection coil 6 having a circuit configuration in which the compensation coil 7 is connected.
Is represented as follows.

Equation 5] _{V e = V b -V d (} 5) V b: voltage detection coil, V _d: as if there is no voltage measured magnetic substance 1 of the compensation coil will V _b = V _d Since it is adjusted, V _e = 0. If there is a magnetic substance 1 to be measured,

[Equation 6] V _e = N _b · S _b · dB / dt (6) N _{b is} the number of turns of the sensor coil, S _{b is} the cross-sectional area of the sensor coil, and B is the magnetic flux density inside the coil.

Here, as shown in the equation (2), B = μ ₀
H has been canceled

[Equation 7] V _e = N _b · S _b · dj / dt (7) and the magnetic characteristic J due to the magnetic material to be measured is obtained.
As described above, the magnetic material 1 to be measured having a small magnetization such as a thin film can be measured with high sensitivity.

Next, characteristic detection irrelevant to magnetic anisotropy will be described. If the magnetic sensor with a compensation coil 4A used in the present invention shown in FIG. 2 is used, since the excitation coil 3, the detection coil 6, and the compensation coil 7 are wound around the circular bobbin 4a, the near magnetic field 9 at the end face a is As shown in the arrow of FIG. 3, it is projected uniformly in all directions, and FIG.
Even with the magnetic substance 1 to be measured having anisotropy as shown in FIG. 5, magnetic characteristics can be obtained at any place of the magnetic sensor 4.

FIGS. 5A and 5B show waveforms of detection signals from the safety wire 21 used as the magnetic body 1 to be measured having magnetic anisotropy, and FIG. 5B shows 1 of FIG. It is an enlarged view of an individual waveform. In (b), a large amplitude portion has a large amount of distortion. According to the device of the present invention as described above, even if the safety wire 21 made of a magnetic material is cracked by a crack or the like, it is possible to obtain a detection signal that can ignore the influence of the crack.

Next, an explanation will be given of the dual function of the data reading sensor and the magnetic characteristic detecting sensor. According to the above equation (6), the detection voltage Ve is proportional to the dJ / dt term. Further, the magnetization J can be written as the following expression (8).

[Equation 8] J = xH (8) x: magnetic susceptibility, H = applied magnetic field strength Since the data written in the safety wire 21 has a different magnetic susceptibility at a portion corresponding to 1/0, it is proportional to the magnetic susceptibility. It appears as a difference in detection voltage. In addition, since the excitation intensity has a characteristic that it gradually decreases from the center distance due to the magnetic field distribution 9 created by the circular excitation coil 3, the detection signal has the amplitude modulation portion and the magnetic field depending on the data position as shown in the detection signal waveform of FIG. The waveform distortion portion due to the magnetic hysteresis characteristic of the body appears at the same time. By analyzing this waveform, data and unique magnetic properties can be obtained simultaneously.

Next, the overall structure of the apparatus of the present invention using such a magnetic sensor 4A with a compensation coil will be described. FIG. 6 shows an embodiment of an authenticity determination device according to the present invention using a magnetic sensor. Reference numeral 22 is a safety protection paper in which a safety line 21 made of a ferromagnetic material is embedded. Reference numeral 10 is a transporting machine for transporting the safety protection paper. 4A is a magnetic sensor with a compensation coil. Reference numeral 2 is an exciting power source for exciting an exciting coil integrated with the magnetic sensor 4A. 8 is a differential amplifier for amplifying the signal detected by the magnetic sensor 4A, 1
Reference numeral 1 is a data reproducing circuit, and 12 is a magnetic characteristic detecting circuit.
Reference numeral 13 is a genuine / counterfeit determination circuit that determines the authenticity from the reproduced data and the output result from the magnetic characteristic detection circuit.

FIG. 7A shows an example of the data reproducing circuit 11, which comprises a detecting circuit 14 and a digitizing circuit 15.
As shown in FIG. 7B, it has a function of detecting a detection waveform Sb from the signal Sa amplitude-modulated by the excitation power supply 2 and converting it into a meaningful 1/0 digital signal Sc.

FIG. 8 shows an example of the magnetic characteristic detection circuit 12, in which a bandpass filter group 16 for separating odd harmonic frequency components based on the excitation frequency and a portion for converting each filter output into a power value are converted. The A / D converter 17 converts an analog value into a digital value. This circuit can be realized by a combination of an A / D converter that directly digitally converts an input signal and a spectrum analyzer.

FIG. 9 shows an example of the authenticity judgment circuit 13. The signals from the data reproduction circuit 11 and the magnetic characteristic detection circuit 12 and the true data and characteristic values stored in the ROMs 18a and 18b are read out and compared by the comparison circuits 19a and 19b.
If they match, the output of the AND circuit 20 determines that the safety protection paper 22 is true, and if they do not match, it determines that it is false. The result is sent to, for example, a display device that performs GO / NO display or a determination processor MH that rejects the safety protection paper 22, and can be effectively used.

[0019]

As described in detail above, according to the present invention, when the authenticity of the safety protection paper is judged by the safety protection wire embedded in the safety protection paper, the data written in the safety protection wire is determined. The magnetic characteristics can be determined by the single magnetic sensor 4A, and the determination can be performed with high accuracy. Therefore, the reliability and the economical effect are extremely excellent.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an example of a magnetic sensor detection circuit with a compensation coil used in the present invention.

FIG. 2 is a schematic perspective view showing an example of a magnetic sensor with a compensation coil used in the present invention.

FIG. 3 is a schematic perspective view for explaining the near magnetic field strength of the magnetic sensor used in the present invention.

FIG. 4 is a lateral direction (a) of the magnetic sensor used in the present invention.
2A and 2B are schematic conceptual perspective views for explaining the measurement of the magnetization characteristics of the magnetic anisotropic magnetic body in the vertical direction (b).

FIG. 5 is a diagram showing a detection signal waveform (a) and its enlarged waveform (b) by the device of the present invention.

FIG. 6 is a connection system diagram showing an embodiment of an authenticity determination device according to the device of the present invention.

7 is a block diagram (a) showing an example of a data reproducing circuit used in the embodiment of FIG. 6 and a diagram (b) showing waveforms of respective parts.

8 is a block diagram showing an example of a magnetic characteristic detection circuit used in the embodiment of FIG.

9 is a block diagram showing an example of a true / false determination circuit used in the embodiment of FIG.

FIG. 10 is an array diagram showing an example of a conventional authenticity determination device.

[Explanation of symbols]

1 Magnetic material to be measured 2 Excitation power supply 3 Excitation coil 4 Magnetic sensor 5 amplifier 6 detection coil 7 compensation coil 8 differential amplifier 9 magnetic vector 10 carrier 11 Data recovery circuit 12 Magnetic characteristic detection circuit 13 True / False Judgment Circuit 14 Detection circuit 15 Digitization circuit 16 Basic band filter 17 A / D converter 18 ROM 19 Comparison circuit 20 AND circuit 21 Safety Lines 22 Safety paper

Front Page Continuation (72) Inventor Ichiro Mizukami 1-741 Kugayama, Suginami-ku, Tokyo Iwasaki Communication Equipment Co., Ltd. (56) References JP-A-8-338864 (JP, A) JP-A-7-32778 (JP, A) JP-A-61-72387 (JP, A) JP-A-61-288181 (JP , A) (58) Fields investigated (Int.Cl. ⁷ , DB name) G07D 7/04 G01R 33/00-33/26

Claims (2)

(57) [Claims] 1. A Ri Do a ferromagnetic material that exhibits a peculiar magnetic hysteresis characteristic to the excitation magnetic field strength of the magnetic field changes, external
The ferromagnetic material so that the magnetic flux density changes with an applied magnetic field
Exciting coils, magnetic flux detecting coils, and compensating coils are integrated to handle safety protection paper in which all the filaments embedded in the processed part of the material have meaningful retention information. A magnetic sensor having a different structure and the safety line detected by the magnetic sensor .
The magnetic sensor is adapted to the hysteresis characteristics of ferromagnetic materials .
Waveform distortion analysis result of detected waveform detected by
The waveform distortion analysis result of the detection waveform obtained in advance corresponding to the peculiar magnetic hysteresis characteristic of the filament is properly matched , and,
Simultaneously read from the safety line by the magnetic sensor
The retained information that has been previously set for the safety line
When it matches with the meaningful holding information, it is determined that the safety protection paper is authentic, and the detection corresponding to the magnetic history characteristic is performed.
Correspondence between the waveform analysis results and the retention information
The authenticity determination device for the safety protection paper, comprising a determination means configured to determine that the image is counterfeit when no match is obtained . 2. The determination means is included in the detection waveform.
Of the detected waveform depending on the level of the predetermined component of the harmonic
Characterized by being configured to obtain waveform distortion analysis results
The authenticity determination device for the safety protection paper according to claim 1.