JP2006060025A - Anti-counterfeit body comprising amorphous magnetic thin film and method for determining authenticity of anti-counterfeit body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To have a unique magnetic characteristic, difficult to forge, and simplify authenticity determination.
SOLUTION: An anti-counterfeit body 2 in which an amorphous magnetic thin film is formed is inserted or embedded in a safety protective paper 1 on a resin base material. The anti-counterfeiting material has a low coercive force and a large saturation magnetic flux density Bm, and can be formed in a short time. When an alternating magnetic field is applied from the exciting coil 3 of the authenticity determination device I to the anti-counterfeit film of the magnetic stripe 2, the magnetic head 4 detects the change in magnetic flux density, and the frequency analyzer 6 outputs the output voltage at a multiple of the exciting frequency. Get the frequency spectrum where The determination circuit 7 determines authenticity by comparing the frequency distribution position of the frequency spectrum of the genuine magnetic thin film and its output value. Since the magnetic anisotropy is small, a detection output is generated regardless of the direction of excitation in authenticity determination.
[Selection] Figure 1

Description

  The present invention relates to an anti-counterfeit body made of an amorphous magnetic thin film that is used by being inserted into or pasted on a security sheet that requires anti-counterfeiting such as securities, and a method for discriminating the anti-counterfeit body.

  Conventionally, as an anti-counterfeiting measure for security papers such as securities, optical change elements such as holograms that are generally difficult to forge, anti-counterfeiting materials by special printing technology, anti-counterfeiting materials by magnetic ink, forgery that reacts to ultraviolet rays or infrared rays There are prevention materials. Furthermore, it is generally known to embed resin, thread or hologram in paper as a forgery prevention material, and these are particularly called safety filaments.

To determine the authenticity of securities with these anti-counterfeiting materials, the method of detecting the amount of reflection or absorption by irradiating ultraviolet rays or infrared rays, or the amount of reflection or absorption of electromagnetic waves is detected. And a method for detecting a magnetic change are known.
In addition, a safety protection paper using the magnetic properties of a material that has been used to store safety assurance data using a ferromagnetic foil, thread, or thin film on the safety filament previously filed by the present applicants, etc. And its true / false discrimination device (see, for example, Patent Document 1).

  In addition, the anti-counterfeit film is excited from the outside so that the magnetic field strength changes in multiple steps, and the magnetic history characteristics of the excited anti-counterfeit film are displayed, or the frequency spectrum included in the magnetic flux density change detected from the anti-counterfeit film There is a method (for example, see Patent Document 2) for determining authenticity by measuring.

  On the other hand, a Co—Zr—Nb-based magnetic material is already known (see, for example, Patent Document 3), and its use is a magnetic core. The alloy composition is Zr of 7 to 15 atomic%, Cr, One or two or more selected from Mo, W, V, Nb, and Ta are 5 to 20 atomic%, and the balance is Co.

  When the anti-counterfeit material using the magnetic material is detected with a predetermined structure and reading conditions (see, for example, Patent Document 4), not all of these composition ranges have unique magnetic characteristics. For example, permalloy, It was difficult to distinguish it from magnetic materials such as Sendust.

  Further, the method of determining authenticity by measuring the frequency spectrum is to apply an AC magnetic field to the anti-counterfeit film from the outside and detect the frequency spectrum included in the magnetic flux density change of the anti-counterfeit film, and the frequency spectrum is Outputs at a ratio of multiples of the excitation frequency of the external AC magnetic field due to the non-linearity of the magnetic history curve of the anti-counterfeit film, and uses the point that the magnitude of each frequency component in each order has a value inherent to the anti-counterfeit film It is. In the method of determining authenticity by measuring the frequency spectrum, since the magnetic thin film of ternary alloy or quaternary alloy has magnetic anisotropy, the frequency depends on the application direction of the excitation magnetic field at the time of authenticity determination. There is a problem that a difference occurs in the spectrum output voltage, the authenticity determination apparatus becomes complicated, and the authenticity determination becomes complicated.

JP-A-7-32778 Japanese Patent Application Laid-Open No. 8-99489 JP 56-84439 A Japanese Patent Application No. 7-18343

  The present invention solves the above-mentioned problems, and the object of the present invention is to provide a forgery prevention material that is very difficult and has a simple configuration in the anti-counterfeiting material that can be used for the safety protection paper and its authenticity determination device. It is an object of the present invention to provide an anti-counterfeiting material having unique magnetic characteristics that can be determined by an authenticity determination device.

  In general, a method of discriminating the material of a ferromagnetic material using a hysteresis curve is performed. However, this method has a problem that it is extremely difficult to discriminate a substance having a very similar history curve. Therefore, in order to solve this problem, in the present invention, the material determination method of the ferromagnetic material is performed by the frequency spectrum analysis method included in the change in magnetic flux density due to the external AC magnetic field. In this discrimination method, the non-linearity of the hysteresis curve is output as a ratio of a multiple of the external AC excitation frequency, and the magnitude of each frequency component in each order has a specific value for each ferromagnet. By knowing the value of the body in advance, it can be easily and accurately determined that the substance is the substance.

1 The present invention is a forgery prevention body comprising a flexible resin substrate and an amorphous magnetic thin film formed on the resin substrate, wherein the amorphous magnetic thin film has a coercive force H _c. Is a magnetic material having a small saturation magnetic flux density Bm and a small magnetic anisotropy, and its composition is represented by Ma-Nb-Xc-Yd-Ze, where M is Co, and N is Fe and Ni. At least one element selected, X is Zr, Y is at least one element selected from the group consisting of W, Nb, Ta and Mo, Z is Cr, V, Ti, Pt, Au and Cu It is an anti-counterfeiting body characterized by being at least one element selected from the group.

  2 According to the present invention, in the amorphous magnetic thin film, the a, b, c, d, and e represent atomic percent, and a + b + c + d + e = 100, 75 ≦ a, 2 ≦ b, 3 ≦ c, 6 ≦ d ≦ 12. The anti-counterfeiting body according to 1 above, wherein 1 is 1 ≦ e.

3. The present invention provides a forgery prevention body comprising a flexible resin base material and an amorphous magnetic thin film formed on the resin base material, wherein the amorphous magnetic thin film has a coercive force H _c. Is a magnetic material having a small saturation magnetic flux density Bm and a small magnetic anisotropy, and its composition is made of Co, Fe, Ni, Zr, Ta, and Cr, and its atomic percentage is Co + Fe + Ni + Zr + Ta + Cr = 100, and 75 ≦ The anti-counterfeit body is characterized in that Co, 2 ≦ Fe + Ni, 3 ≦ Zr, 6 ≦ Ta ≦ 12, and 1 ≦ Cr.

  4 The present invention is characterized in that a frequency spectrum of harmonics included in a change in magnetic flux density generated in response to an alternating magnetic field applied to the amorphous magnetic thin film of the anti-counterfeiting body is unique to the amorphous magnetic thin film. 4. The anti-counterfeiting body according to the above 1, 2 or 3, characterized by exhibiting a unique magnetic history characteristic having a value of

  5. In the present invention, the thickness of the flexible resin substrate is 4 to 30 microns, and the thickness of the amorphous magnetic thin film formed thereon is 0.1 to 0.5 microns. It is a forgery prevention body of said 1, 2, or 3 characterized by the above-mentioned.

  6 In the present invention, an alternating magnetic field is applied to a magnetic thin film provided on the anti-counterfeit body that is the object of authenticity determination, and a frequency spectrum of harmonics included in a change in magnetic flux density generated in response thereto, The anti-counterfeiting material according to any one of 1 to 5 above, wherein authenticity determination is performed by coincidence / non-coincidence with the harmonic frequency spectrum of the genuine amorphous magnetic thin film according to any one of 1 to 5. This is a true / false discrimination method.

  The present invention provides an anti-counterfeit body made of an amorphous magnetic thin film having a unique magnetic hysteresis characteristic that generates a harmonic spectrum of an AC frequency when an AC magnetic field is applied to the inside and / or surface of a paper layer. Therefore, counterfeiting is difficult and safety is extremely high. In addition, the authenticity determination device according to the present invention can easily and quickly determine the authenticity of the safety protection paper provided with the anti-counterfeit body of the present invention, with a simple device configuration. The handling and reliability of safety protective paper can be remarkably enhanced.

  In general, when trying to discriminate the material of a ferromagnetic material with one history curve, if the history curve is a very similar substance, it is very difficult to discriminate by using a material whose material to be inspected is adjusted. However, by using the frequency spectrum analysis method included in the magnetic flux density change due to the external AC magnetic field according to the present invention, the nonlinearity of the hysteresis curve is output at a ratio of a multiple of the external AC excitation frequency. Since the magnitude in each order has a value specific to each ferromagnet, knowing the value of a ferromagnet having a certain eigenvalue in advance makes it possible to easily and accurately discriminate the substance. It becomes like this.

The present invention relates to a safety protective paper in which an anti-counterfeit body in which an amorphous magnetic thin film having unique magnetic properties is formed on a flexible resin substrate is inserted, and a method for determining the authenticity of the safety protective paper.
As shown in FIG. 1 (a), the safety protection paper 1 with the anti-counterfeit body inserted therein is an anti-counterfeit body (magnetic line, A magnetic thread) 2 is inserted or embedded, and as shown in FIG. 1B, an amorphous magnetic material having specific magnetic properties on a flexible resin substrate 2B (for example, a polyester film). A thin film 2A is formed.

The amorphous magnetic thin film 2A is represented by Ma-Nb-Xc-Yd-Ze, where M is Co, N is at least one element selected from the group consisting of Fe and Ni, X is Zr, Y is at least one element selected from the group consisting of W, Nb, Ta and Mo, Z is at least one element selected from the group consisting of Cr, V, Ti, Pt, Au and Cu, , A, b, c, d, and e represent atomic percent, and a + b + c + d + e = 100, 75 ≦ a, 2 ≦ b, 3 ≦ c, 6 ≦ d ≦ 12, and 1 ≦ e. Amorphous magnetic thin film 2A has a small coercive force H _c, large saturation magnetic flux density Bm, it is desirable magnetic anisotropy is small. The film thickness of the amorphous magnetic thin film 2A is desirably 0.1 microns or more and 0.5 microns or less. As the flexible resin substrate 2B, a polyester film (PET) or the like is suitable, and the thickness of the substrate is desirably 4 microns or more and 30 microns or less.

As the amorphous magnetic thin film 2A, in the present invention, Co, Fe, Ni, Zr, Ta, Cr (component ratio (atomic percent): 75 ≦ Co, 2 ≦ Fe + Ni, 3 ≦ Zr, 6 ≦ Ta ≦ 12) A hexagonal alloy amorphous magnetic thin film made of 1 ≦ Cr) was employed.
The amorphous magnetic thin film, by coercivity H _c is small, it is possible spectrum detected by field intensity alternating magnetic field is hardly applied during the authenticity discrimination, it facilitates discrimination between other magnetic material. Further, since the transmission magnetic flux density Bm on the target of the sputtering apparatus is large and the magnetic anisotropy is small, the frequency spectrum output voltage can be detected regardless of the direction of the alternating magnetic field applied to the amorphous magnetic thin film. it can. When an amorphous magnetic thin film is formed by a magnetron sputtering method, considering that the magnetic flux density on the target causes thermal damage to the film formation efficiency and the polyester film (PET) that is the film formation target, It is necessary that the transmitted magnetic flux density is large.

It is desirable that the magnetic alloy serving as a target easily transmits magnetic flux (the transmitted magnetic flux density Bm is large). The basis for this will be described below.
In the magnetron sputtering method, a magnet is placed on the back surface of a target to form an orthogonal electromagnetic field, thereby causing electrons to perform a cycloidal motion and confined in the vicinity of the target. As a result, high-density plasma is generated, and electrons and plasma are prevented from colliding with the resin base material, thereby improving the sputtering rate, preventing the temperature rise of the resin base material, and preventing damage to the resin base material. It can be realized at the same time. However, since the magnetic metal target is difficult to transmit magnetism, it is difficult to obtain the electromagnetic field strength necessary for confining electrons in the vicinity of the target as compared with the nonmagnetic alloy target. It is desirable that it is easy to transmit (the transmitted magnetic flux density Bm is large).

As shown in FIG. 2, when Co is less than 75%, the saturation magnetic flux density (Bm) decreases, so 75% ≦ Co is desirable.
As shown in FIG. 3, when at least one element selected from the group consisting of Fe and Ni is less than 2%, the magnetic anisotropy becomes strong, so 2% ≦ Fe + Ni is desirable.
As shown in FIG. 4, if Zr is less than 3%, the coercive force (H _c ) increases, so 3% ≦ Zr is desirable.
As shown in FIG. 5, when at least one element selected from the group consisting of W, Nb, Ta and Mo is less than 6%, the coercive force (H _c ) increases, and when it is 12% or more, the melting method is used. 6% ≦ Ta ≦ 12% is desirable because wrinkles and the like frequently occur on the target and cause abnormal discharge during deposition.
As shown in FIG. 6, when the content of at least one element selected from the group consisting of W, Au, and Cu is less than 1%, the transmitted magnetic flux density (kG) on the target is small, and a flexible resin substrate is used. Since certain polyester films (PET) are damaged by heat, 1% ≦ Cr is desirable.

  The unique magnetic history characteristic is that when an external AC magnetic field is applied to a magnetic thin film (anti-counterfeiting film), a magnetic substance is included in the frequency component of the frequency spectrum included in the magnetic flux density change of the anti-counterfeit film corresponding to the magnetic field. An output value peculiar to a thin film is generated. Hereinafter, a true / false discrimination method using such a unique magnetic history characteristic is referred to as a true / false discrimination method using a frequency spectrum. In the authenticity determination method using the frequency spectrum, the frequency spectrum is output at a ratio of a multiple of the excitation frequency of the external AC magnetic field due to the non-linearity of the magnetic history curve of the anti-counterfeit film, and the magnitude of the output value at each order of this frequency component In other words, the frequency component and its output value (hereinafter referred to as a frequency spectrum pattern) have a value unique to each magnetic thin film.

  In general, when trying to discriminate the material of a ferromagnetic material with one history curve, if the history curve is a very similar substance, it is very difficult to discriminate by using a material whose material to be inspected is adjusted. In the present invention, the authenticity determination method based on the frequency spectrum is adopted. The frequency / frequency spectrum pattern unique to the genuine ferromagnet set in advance and the frequency spectrum pattern measured by the frequency spectrum authenticity discrimination method are compared and verified. Or whether it is a fake.

FIG. 7 is a conceptual diagram of the authenticity determination device 9 employing the frequency spectrum analysis method.
An anti-counterfeiting body in which an exciting current flows from the AC power source V ₀ to the exciting coil 3 through the current adjusting resistor 9 (R ₁ , R ₂ , R ₃ ) and the exciting current control switch S and is inserted or buried in the safety protective paper 1 An alternating magnetic field is applied to the magnetic thin film 2A of 2 (magnetic wire, magnetic thread). If necessary, the number of switch switching stages may be increased or a variable resistor may be used, and the same effect can be obtained by changing the voltage Vo of the AC power supply V ₀ . An instruction IC for current control is given from the number of determinations 7 so that the intensity of excitation can always be monitored. In order to excite the anti-counterfeit body 2 (magnetic wire, magnetic thread) efficiently in the exciting coil 3, a core having a large magnetic permeability is inserted in the center of the coil. A magnetic head 4 is provided on the side facing the exciting coil 3 (not shown) across the magnetic thin film 2A (not shown) or on the same side (not shown) as the exciting coil 3, and from the magnetic thin film 2A excited by the magnetic head 4 Changes in magnetic flux density are detected. Similar effects can be obtained by using a Hall element, MR element, magnetic coil, or the like as long as it can detect a change in magnetic flux density other than the magnetic head 4. A voltage proportional to the change in magnetic flux density detected by the magnetic head 4 is amplified by the amplifier 5. The detection voltage amplified by the amplifier 5 is subjected to frequency analysis by the frequency analyzer 6 and then determined by the determination circuit 7. The determination circuit 7 uses the frequency component obtained from the magnetic thin film 2A to be analyzed and its output value (frequency spectrum pattern) as a preset reference (genuine) frequency component of the magnetic thin film and its output value ( If it matches with the frequency spectrum pattern), it is determined that the anti-counterfeiting body 2 (magnetic wire, magnetic thread) including the inspected magnetic thin film 2A is authentic or authentic. If it is different, it is judged to be counterfeit. In this way, the determination circuit 7 determines whether the frequency spectrum pattern is in proportion to the true material value and matches or does not match. This determination circuit 7 generally uses a microcomputer, and has a function of reading the analysis result of the frequency analyzer 6 described above, a function of controlling the excitation current, and a function of previously storing the spectrum intensity of the true material. The function of the frequency analyzer 6 can be performed by this microcomputer.

  FIG. 8 is a configuration diagram of the frequency analyzer 6. The magnetic detection signal from the safety filament 2 input through the amplifier 5 is cut by the low-pass filter 62 over the frequency for analysis. The band-limited analog signal is converted into a digital signal by the A / D converter 63. The digitized signal is stored in the temporary memory 64. Information stored in the memory 64 is Fourier-transformed by the FFT calculator 65 and converted into frequency spectrum components. The converted frequency spectrum component is stored in the memory 66 and is referred to at the time of determination as an analysis result. These controls are performed by the main control unit 61.

In the present invention, as the amorphous magnetic thin film 2A formed on the anti-counterfeiting body 2 (magnetic wire, magnetic thread) inserted or embedded in the safety protective paper 1, the following 6-element alloy amorphous magnetic material is used. It was clarified that the body thin film is the optimal material.
The ternary alloy amorphous magnetic thin film of the present invention is composed of Co, Zr, Ni, Ta, Fe, Cr (hexent alloy) (component ratio (%): 75 ≦ Co, 2 ≦ Fe + Ni, 3 ≦ Zr, 6 ≦ Ta ≦ 12, 1 ≦ Cr).

A quaternary alloy amorphous magnetic thin film of the present invention and a quaternary alloy magnetic thin film made of Co, Zr, Ni, and Cu (quaternary alloy) conventionally employed (conventional example) Comparison of the material properties of
FIG. 9 and FIG. 10 show the results of analysis by frequency spectrum analysis for two types of ferromagnetic materials having similar magnetic properties such as magnetic permeability. The horizontal axis represents the frequency (Hz), and the vertical axis represents the spectrum output value (V). In the drawing, the excitation spectrum is omitted for easy comparison. FIG. 9 shows a ternary alloy amorphous magnetic thin film, and FIG. 10 shows a quaternary alloy amorphous magnetic thin film. As shown in FIG. 11, since the ternary alloy amorphous magnetic thin film has no magnetic anisotropy, the output voltage of the frequency spectrum can be detected regardless of the direction of the alternating magnetic field applied to the thin film. In other words, in the case of a strip-shaped ternary alloy amorphous magnetic thin film, there is no significant difference in the output value (V) of the spectrum in both the longitudinal direction and the width direction. On the other hand, since the quaternary alloy amorphous magnetic thin film has magnetic anisotropy, the direction of the AC magnetic field applied to the thin film is particularly related, and the voltage output of the frequency spectrum can be detected only in a specific direction. That is, in the case of a strip-like quaternary alloy amorphous magnetic thin film, there is a characteristic that a voltage output value (V) of a frequency spectrum is obtained only when excitation is performed in either the longitudinal direction or the width direction.

The characteristics of the ternary alloy amorphous magnetic thin film of the present invention and the conventional quaternary alloy amorphous magnetic thin film are compared at the film forming stage.
In both cases, a 4-inch RF sputtering apparatus was used, and the sputtering conditions were set as follows to form a film.
Temperature: 24 ° C., Humidity: 60%, AC power supply, ultimate pressure: 5 × 10 ⁻⁴ Pa, sputtering pressure: 3 × 10 ⁻¹ Pa, Ar flow rate: 20 SCCM, sputtering power: 500 W, pre-sputtering time: 10 minutes Sputtering time: 12 minutes 30 seconds (assuming a film thickness of 0.25 μm). As a result of measuring the film thickness (μm) of the formed magnetic thin film, the quaternary alloy amorphous magnetic thin film of the present invention is 0.2681 μm as shown in FIG. The amorphous magnetic thin film was 0.2437 μm.
As a result, it has been found that the ternary alloy amorphous magnetic thin film has higher film forming efficiency than the quaternary alloy amorphous magnetic thin film, and a thick film can be obtained in the same sputtering time. . Moreover, if it is the thing of the same film thickness, a 6-element alloy amorphous magnetic thin film can be formed in a shorter time than a 4-element alloy amorphous magnetic thin film.

  Further, the comparison result of the transmitted magnetic flux density (kG) on the target between the ternary alloy amorphous magnetic thin film and the quaternary alloy amorphous magnetic thin film of the present invention is as shown in FIG. It was proved that the alloy amorphous magnetic thin film had a higher transmission magnetic flux density on the target than the quaternary alloy amorphous magnetic thin film.

As described above, the 6-way alloy amorphous magnetic thin film of the present invention has a small coercive force H _c, large saturation magnetic flux density Bm, it anisotropy is small has been demonstrated from the experimental results.

  In an embodiment of the present invention, an amorphous magnetic thin film (hexent alloy) made of Co, Fe, Ni, Zr, Ta, and Cr (component ratio (%): 75 ≦ Co, 2 ≦ Fe + Ni, 3 ≦ Zr, 6 ≦ Ta ≦ 12, 1 ≦ Cr), but as the amorphous magnetic thin film, at least one element selected from the group consisting of Fe and Ni instead of Fe + Ni is replaced with Ta. At least one element selected from the group consisting of W, Nb, Ta and Mo, and at least one element selected from the group consisting of Cr, V, Ti, Pt, Au and Cu instead of Cr Amorphous magnetic thin films can also obtain similar characteristics.

  The present invention provides an anti-counterfeit body made of an amorphous magnetic thin film having a unique magnetic hysteresis characteristic that generates a harmonic spectrum of an AC frequency when an AC magnetic field is applied to the inside and / or surface of a paper layer. Therefore, counterfeiting is difficult and safety is extremely high. In addition, the authenticity determination device according to the present invention can easily and quickly determine the authenticity of the safety protection paper provided with the anti-counterfeit body of the present invention, with a simple device configuration. The handling and reliability of safety protective paper can be remarkably enhanced.

  In general, when trying to discriminate the material of a ferromagnetic material with one history curve, if the history curve is a very similar substance, it is very difficult to discriminate by using a material whose material to be inspected is adjusted. However, by using the frequency spectrum analysis method included in the magnetic flux density change due to the external AC magnetic field according to the present invention, the nonlinearity of the hysteresis curve is output at a ratio of a multiple of the external AC excitation frequency. Since the magnitude in each order has a value unique to each ferromagnet, knowing the value of a ferromagnet having a certain eigenvalue in advance makes it possible to easily and accurately discriminate the substance. It becomes like this.

(A) It is a block diagram of the forgery prevention body (a magnetic filament, a magnetic thread) which consists of a ternary alloy amorphous magnetic thin film of this invention. (B) It is a block diagram of the forgery prevention body by which the forgery prevention body (magnetic filament, magnetic thread) of this invention was inserted or embed | buried. It is a figure which shows the relationship (measurement result) of content of Co and saturation magnetic flux density (Bm) in the 6-element (multi-element) alloy amorphous magnetic thin film of this invention. It is a figure which shows the relationship (measurement result) of content of Fe and signal output (mV) in the 6-element (multi-element) alloy amorphous magnetic thin film of this invention. It is a figure which shows the relationship (measurement result) of content of Zr and coercive force (Hc) in the 6-element (multi-element) alloy amorphous magnetic thin film of this invention. It is a figure which shows the relationship (measurement result) of content of Nb and coercive force (Hc) in the 6-element (multi-element) alloy amorphous magnetic thin film of this invention. It is a figure which shows the relationship (measurement result) of content of Cr and transmitted magnetic flux density (kG) in the 6-element (multi-element) alloy amorphous magnetic thin film of this invention. It is a block diagram of the forgery prevention body of this invention and the authenticity determination apparatus of this forgery prevention body. It is a block diagram of the frequency analyzer in the authenticity determination apparatus of the forgery prevention body of this invention. It is a figure which shows the analysis result (frequency spectrum pattern) by the frequency spectrum analysis method of the ternary alloy amorphous magnetic thin film (film-formed by the sputtering method) of this invention. It is a figure which shows the analysis result (frequency spectrum pattern) by the frequency spectrum analysis method of the conventional quaternary alloy amorphous magnetic thin film (formed by sputtering method). The direction of application of an alternating magnetic field in the ternary alloy amorphous magnetic thin film (formed by sputtering) of the present invention and the conventional quaternary alloy amorphous magnetic thin film (formed by sputtering) ( It is the figure which compared the output signal (mV) characteristic with respect to the width direction and the length direction). It is the figure which compared the quaternary alloy amorphous magnetic thin film of this invention, and the conventional quaternary alloy amorphous magnetic thin film about the film thickness formed by the sputtering method. It is the figure which compared the ternary alloy amorphous magnetic thin film of this invention, and the conventional quaternary alloy amorphous magnetic thin film about the permeation | transmission magnetic flux density on the target of a sputtering device.

Explanation of symbols

1 Safety protection paper 1A Paper (or sheet)
2 Anti-counterfeit body (magnetic wire, magnetic thread)
2A Magnetic thin film 2B Resin substrate 3 Excitation coil 4 Magnetic head 5 Amplifier 6 Frequency analyzer 61 Main controller 62 Low pass filter 63 A / D converter 64 Memory 65 FFT calculator 66 Memory 7 Determination circuit

Claims (6)

A forgery prevention member consisting of an amorphous magnetic thin film formed on the resin substrate and the resin base material on a flexible, the amorphous magnetic thin film has a small coercive force H _c, saturation magnetic flux A magnetic material having a high density Bm and a small magnetic anisotropy, the composition of which is represented by Ma-Nb-Xc-Yd-Ze, where M is Co, and N is at least one selected from Fe and Ni Kinds of elements, X is Zr, Y is at least one element selected from the group consisting of W, Nb, Ta and Mo, Z is selected from the group consisting of Cr, V, Ti, Pt, Au and Cu An anti-counterfeit body comprising at least one element. In the amorphous magnetic thin film, a, b, c, d and e represent atomic percent, and a + b + c + d + e = 100, 75 ≦ a, 2 ≦ b, 3 ≦ c, 6 ≦ d ≦ 12, 1 ≦ e. The anti-counterfeit body according to claim 1, wherein A forgery prevention member consisting of an amorphous magnetic thin film formed on the resin substrate and the resin base material on a flexible, the amorphous magnetic thin film has a small coercive force H _c, saturation magnetic flux A magnetic material having a large density Bm and a small magnetic anisotropy, the composition of which is made of Co, Fe, Ni, Zr, Ta, and Cr, the atomic percentage of which is Co + Fe + Ni + Zr + Ta + Cr = 100, 75 ≦ Co, 2 ≦ An anti-counterfeiting body characterized by Fe + Ni, 3 ≦ Zr, 6 ≦ Ta ≦ 12, 1 ≦ Cr. A frequency spectrum of harmonics included in a change in magnetic flux density generated in response to an alternating magnetic field applied to the amorphous magnetic thin film of the anti-counterfeit body has a unique value that is unique to the amorphous magnetic thin film. The anti-counterfeiting body according to claim 1, wherein the anti-counterfeiting body exhibits excellent magnetic history characteristics. The thickness of the flexible resin substrate is 4 to 30 microns, and the thickness of the amorphous magnetic thin film formed thereon is 0.1 to 0.5 microns. The forgery prevention body according to claim 1, 2, or 3. 6. An AC magnetic field is applied to the magnetic thin film provided on the anti-counterfeit body that is the object of authenticity determination, and a frequency spectrum of harmonics included in a change in magnetic flux density generated in response thereto, 6. The authenticity of the anti-counterfeiting material according to any one of claims 1 to 5, wherein the authenticity determination is performed by matching or mismatching with a harmonic frequency spectrum of the genuine amorphous magnetic thin film described above. How to determine.

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