JP2011123722A - Security thread, security paper sheet and verification method - Google Patents

Abstract

[PROBLEMS] To record not only a security thread having an optical function such as a hologram but also magnetic information, and recording the optical information possessed by the hologram or the like as magnetic information on the security thread, It is an object to provide a security thread that is more difficult to forge by making it possible to read and compare optical information and magnetic information.
A security thread comprising a reflective layer, a hologram, or a diffraction grating on one surface of a base material, and a magnetic layer containing a magnetic material as a main component on the other surface.
[Selection] Figure 1

Description

  The present invention relates to a security thread for preventing counterfeiting used in banknotes, securities and the like, a security paper using the security thread, and a verification method thereof.

  Conventionally, a security thread has been used as security for preventing counterfeiting in banknotes and securities by encroaching on the paper. For example, if a hologram is used for the security thread, it is adopted as a forgery prevention technique by taking advantage of the fact that it is difficult to reproduce by color copy or image capture by a scanner. This is mainly used for visual authenticity determination.

  On the other hand, as a method for performing verification by a reader provided in ATM or the like, there is a method of providing a magnetic layer on a security thread. For example, Patent Document 1 proposes a method of providing a magnetic bar code on a security thread. Patent Documents 2 and 3 propose a method for determining authenticity by using a plurality of layers of magnetic material or providing a plurality of security threads and reading the magnetic information.

  However, with the above-described technology, for example, even with a copy-preventing hologram, if a recent digital color copier with improved performance is difficult to reproduce a deep image peculiar to the hologram, the metallic luster is reproduced well. On top of that, you may get an elaborate copy that can be mistaken for the real thing at first glance. In addition, due to the recent improvement in technology, it is not possible to obtain a hologram with almost the same appearance as the real thing, so it is possible to forge without relying on a copy, just by making it a security thread with a hologram, Effective anti-counterfeiting measures are becoming difficult.

  In addition, in the method of providing magnetic information on the security thread for machine reading, it is only necessary to provide a bar code, but using multiple layers of magnetic material or providing multiple security threads is very structural. This is a complicated and expensive factor. Also, some magnetic materials are readily available, and it is not impossible to create something that is not similar unless it really has special magnetic properties. On top of that, even if an image such as a hologram is simply provided on the surface, it can be said that there is essentially no significant difference from a security thread based on visual judgment using a conventional hologram if it is simply used for visual verification. .

Japanese Patent Laid-Open No. 11-245569 JP 2002-266290 A JP-A-2005-232617

  In order to solve the above problems, the present invention adds a function capable of recording magnetic information to a security thread having an optical function such as a hologram, thereby converting the optical information possessed by the hologram into magnetic information. It is an object of the present invention to provide a security thread that is more difficult to forge by recording in a security thread and comparing the optical information and magnetic information to determine authenticity.

  In order to solve the above problems, the invention according to claim 1 is provided with a hologram or a diffraction grating on one surface on a base material and a magnetic layer mainly composed of a magnetic material on the other surface. This is a security thread characterized by that.

  According to a second aspect of the present invention, a reflective layer is provided on one surface of a substrate, a magnetic layer mainly composed of a magnetic material is provided on the other surface, and a part of the reflective layer is provided. It is a security thread characterized by removing.

  According to a third aspect of the present invention, in the security thread according to the first or second aspect, information synchronized with the hologram, the diffraction grating, or the reflective layer is recorded in the magnetic layer. It is.

  The invention according to claim 4 is characterized in that the magnetic layer is provided in a pattern in a state of being synchronized with the hologram, the diffraction grating, or the reflective layer. Security thread.

  According to a fifth aspect of the present invention, information that can be converted into reflected light information by the same or an arbitrary algorithm as the reflected light information by the hologram, the diffraction grating, or the reflective layer is recorded on the magnetic layer. The security thread according to any one of claims 1 to 4, wherein the security thread is provided.

  According to a sixth aspect of the present invention, there is provided a security sheet comprising the security thread according to any one of the first to sixth aspects.

  The invention according to claim 7 is the security thread according to any one of claims 1 to 5 or the security paper verification method according to claim 6, wherein the hologram or the diffraction grating or the A signal obtained by irradiating reflected light (including diffracted light) obtained by irradiating light to the reflective layer and converted by reflected light information obtained by the same or arbitrary algorithm, and magnetic information recorded on the magnetic layer This is a verification method characterized in that a true / false determination is performed on the reflected signal by determining the constancy of the phase difference between them and the coincidence of the periods.

  According to the present invention, since the hologram, diffraction grating, or reflection layer and the portion from which the hologram, diffraction grating, or reflection layer has been removed are provided on the surface, it is possible to reproduce reflected light information depending on the presence or absence of the reflected light or diffracted light. In addition, since information converted by an arbitrary algorithm based on reflected light information is recorded as magnetic information in the magnetic layer on the back surface, and this can be determined by reading and comparing, High security can be imparted.

Sectional drawing which shows an example of a structure of a security thread | sled. Sectional drawing which shows an example of a structure of a security thread | sled. Sectional drawing which shows an example of a structure of a security thread | sled. Sectional drawing which shows an example of a structure of a security thread | sled. Sectional drawing which shows an example of a security paper. Sectional drawing which shows an example of a security paper. The conceptual diagram which shows the reading method of the reflected light information and magnetic information at the time of using a reflection layer. The conceptual diagram which shows the reading method of the reflected light information and magnetic information at the time of using a hologram or a diffraction grating. Explanatory drawing which shows an example of a verification system. Explanatory drawing which shows an example of the state of the front and back of a security thread. Explanatory drawing which shows an example of the state of the front and back of a security thread (when magnetic information is recorded). An example of a measurement result of magnetic information and reflected light information from a reflective layer (when magnetic information is recorded). An example of a measurement result of magnetic information and reflected light information from a reflective layer (when magnetic information is not recorded). An example of magnetic information and reflected light information from a hologram or diffraction grating (when magnetic information is recorded). An example of magnetic information and reflected light information from a hologram or diffraction grating (when magnetic information is recorded). An example of magnetic information and reflected light information from a hologram or diffraction grating (when magnetic information is not recorded).

Hereinafter, the invention will be described in detail with reference to the drawings.
FIG. 1 is a cross-sectional view showing an example of the configuration of a security thread 1 according to the present invention. The security thread 1 is provided with a magnetic layer 3 on one surface of a substrate 2 and a reflective layer 4 on the other surface. Since the reflective layer 4 is partially provided, the reflective part 5 and the non-reflective part 6 exist on the same plane.

  The base material 2 serves as a support for the reflective layer 4 and the magnetic layer 3, and conventionally known plastic materials and paper materials can be used. In general, however, availability, cost, strength, etc. In consideration of the surface, it is preferable to use a polyethylene terephthalate (hereinafter abbreviated as PET) film having a thickness of about 3 to 50 μm, but it is not limited thereto. In order not to adversely affect the reflective layer 4, the surface of the substrate 2 is preferably smooth. However, if the smoothness is low, a smooth layer may be used in combination as appropriate. Moreover, in order to make the adhesiveness of the base material 2, the magnetic layer 3, and the reflection layer 4 favorable, a conventionally well-known anchor layer may be provided or the surface of the base material 2 may be corona-treated.

  The magnetic layer 3 is formed with a conventionally known magnetic powder and a binder resin as main components. As the magnetic powder, for example, hard magnetic materials such as iron, γ-iron oxide, magnetite, Co-deposited γ-iron oxide, barium ferrite, strontium ferrite, and alnico can be used.

  The reflective layer 4 is usually provided on the surface. As a method of providing the reflective layer 4, a method of forming a metal thin film such as aluminum is common, but is not limited thereto. Of course, a protective layer for imparting durability and an anchor layer for improving the adhesion between the metal thin film and the resin may be provided on the reflective layer 4.

  Such a reflective layer 4 is provided not partially but partially. Therefore, as shown in FIG. 1, the hue of the base material 2 or the magnetic layer 3 serving as a base is observed in a portion where the reflective layer 4 is not present. In addition, since there is almost no reflection of the reflective layer 4 at that portion, it is possible to record information with or without reflection by utilizing the fact that sufficient intensity of reflected light cannot be obtained by irradiation light from an appropriate light source. As a method of partially providing the reflective layer 4, for example, a method of performing partial vapor deposition, a method of performing etching by mask printing, a method of destroying with a light beam such as a laser, a method of thermally destroying with a thermal head, etc., gloss There is a method of partially providing a certain ink, etc., which can be selected as necessary.

FIG. 2 is also a cross-sectional view showing an example of the configuration of the security thread. A magnetic layer 3 is provided on one surface of the substrate 2 and a reflective layer 4 is provided on the other surface. The reflective layer 4 is composed of a vapor deposition anchor layer 11, a metal vapor deposition layer 12, and a mask layer 13. An example is shown. The vapor deposition anchor layer 11 is unnecessary if the adhesion between the metal vapor deposition layer 12 and the substrate 2 is sufficient. The metal vapor deposition layer 12 is once provided on the entire surface, and a mask layer 13 having a desired shape is provided thereon. The mask layer refers to an etching mask, and is a layer that functions as an etching mask when the metal vapor deposition layer underneath is etched away. As a method of providing the mask layer 13, for example, a normal printing method can be used. For example, a gravure printing method, a screen printing method, an offset printing method, a flexographic printing method, or the like is selected as necessary. When the mask layer 13 is provided and then immersed in an etching solution to dissolve the exposed portion of the metal vapor-deposited layer 12, the metal vapor-deposited layer 12 can be left along the shape of the mask layer 13.

  FIG. 3 is also a cross-sectional view showing an example of the configuration of the security thread 1 according to the present invention. The security thread 1 is provided with a hologram or diffraction grating 4 ′ on one surface of a substrate 2 and a magnetic layer 3 on the other surface. Since the hologram or diffraction grating 4 ′ is partially provided, a portion with the hologram or diffraction grating and a portion without it corresponding to the reflection portion 5 and the non-reflection portion 6 exist on the same plane. The diffraction grating may be an assembly of minute diffraction gratings, and by setting the direction of the minute diffraction gratings, an image or a character can be displayed or information to be set can be reflected. FIG. 3 shows an example in which the hologram or diffraction grating 4 ′ is partially provided, but it may be formed on the entire surface or in a wide range. This is because a hologram is a diffraction grating reflecting image information, and therefore contains information reflecting image information. In the case of a diffraction grating, when information such as images, characters, patterns, and the like are included by combining fine diffraction gratings having different diffraction directions, the same as in the case of a hologram.

  The base material 2 serves as a support for the hologram or diffraction grating 4 'and the magnetic layer 3, and conventionally known plastic materials and paper materials can be used. In view of strength, a polyethylene terephthalate (hereinafter abbreviated as PET) film having a thickness of about 3 to 50 μm is preferably used, but is not limited thereto. The substrate 2 preferably has a smooth surface, but the smoothness may be low to some extent, for example, by providing a smoothing layer for smoothing.

  As a method of providing the hologram or diffraction grating 4 ′, a method of forming a metal thin film such as aluminum by copying (transferring) the shape of the hologram or diffraction grating previously formed on the stamper onto the resin via hot pressure is generally used. But not limited to this. Of course, a protective layer for imparting durability and an anchor layer for improving the adhesion between the metal thin film and the resin may be provided on the hologram or the diffraction grating 4 '. In addition to the hologram or diffraction grating 4 'used for reading, other hologram images or other diffraction gratings may be provided within a range that does not interfere with reading. For example, those having different spatial frequencies and diffraction directions often do not affect reading, and can be provided on the same surface.

Diffraction of the hologram or diffraction grating 4 ′ is made up of an incident angle α (angle formed between the normal line and the incident light), a diffraction angle β (angle formed between the normal line and the diffracted light), the wavelength λ of the incident light, and the distance d between the diffraction gratings. It is shown by the relationship of Formula 1. Here, if the incident angle is taken in the normal direction, since α = 0 and sin α = 0, for example, when incident from the normal direction to a diffraction grating with a 1 μm interval with a laser beam of 635 nm, the angle is approximately θ = ± 40 degrees. Since diffracted light appears, it may be received at this angle.
(Formula 1) d = mλ / (sin α−sin β) (m = ± 1, ± 2, ± 3...)

  The magnetic layer 3 is formed with a conventionally known magnetic powder and a binder resin as main components. Examples of magnetic powder include hard magnetic materials such as iron, γ-iron oxide, magnetite, Co-coated γ iron oxide, barium ferrite, strontium ferrite, and alnico, as well as nickel, permalloy, sendust, and carbonyl iron. A soft magnetic material can also be used, and the material is not limited to this. In the case of a hard magnetic material, magnetic recording can be performed on itself, and in the case of a soft magnetic material, reading can be performed with a magnetic bias provided in a pattern.

  FIG. 4 is also a cross-sectional view showing an example of the configuration of the security security thread 1. In the case of using the above-described soft magnetic material or a hard magnetic material, the example is shown in which the magnetic layer 3 is provided in a pattern.

  FIG. 5 is a cross-sectional view showing an example of the security paper 21 in a state where the above-described security thread 1 is inserted into paper. A state is shown in which the security thread 1 is sandwiched between the interleaving paper 22 and the window opening 23 is provided in a part of the paper on the side where the reflective layer 4 is formed.

  FIG. 6 is also a cross-sectional view showing an example of the security paper 21 in a state where the security thread 1 is rolled into the paper. The security thread 1 is sandwiched between crease paper 22, and a window opening 23 is provided on a part of the paper on the side where the hologram or diffraction grating 4 'is formed.

  FIG. 7 is an explanatory diagram showing the concept of a method for recording magnetic information on the magnetic layer 3. A reflected light 32 is obtained for the incident light 31 to the reflecting portion 5. On the other hand, with respect to the incident light 33 on the non-reflecting part 6, the reflected light 34 of the non-reflecting part 6 cannot provide sufficient intensity necessary for detection. Therefore, when the incident light 31 to the reflecting portion 5 is scanned from the left to the right in FIG. 7, information on the presence of reflected light → none → yes → no → yes is obtained. At this timing, if the magnetic recording on the magnetic layer 3 on the back surface is magnetically recorded using the magnetic head 35 with the reflection portion facing right and the non-reflection portion magnetically recording leftward, the same information as the reflected light information on the front surface Can be magnetically recorded. Furthermore, instead of such direct recording, it is also possible to encode several reflected light information collectively and record this code on the magnetic layer 3. Furthermore, information obtained by further converting the encoded reflected light information by an arbitrary algorithm can be recorded in the magnetic layer 3.

  FIG. 8 is an explanatory diagram showing a concept of a method of reading reflected light information and magnetic information from a hologram or diffraction grating. In order to read information on the hologram or diffraction grating 4 ′, an irradiation unit 40 and a light receiving unit 41 are provided so that reflected light (diffracted light) from the hologram or diffraction grating can be received. A magnetic reading unit 42 for reading magnetic information is installed on the back surface. A magnetic head 35 or a magnetic sensor can be used as the magnetic reading unit 42. However, since the distance between the magnetic reading unit 42 and the security thread 1 becomes relatively long when the paper is inserted into paper, a magnetic sensor with higher sensitivity is used. Is preferred. However, when performing magnetic recording with a hard magnetic material, it is necessary to use a magnetic material having a coercive force that does not erase the recording with a permanent magnet in the magnetic sensor. The output signals of both the light receiving unit 41 and the magnetic reading unit 42 are sent to the verification unit for verification.

  FIG. 9 is an explanatory diagram showing an example of the verification method. The reflected light information obtained from the reflective layer 4 and the magnetic information obtained from the magnetic layer 3 are compared by a predetermined algorithm, and it is determined as true or false depending on whether they match. Specifically, the signal reflecting the reflected light information is compared with the signal reflecting the magnetic information recorded in the magnetic layer to determine how constant the phase difference between the two is, and how much the period between the two is equal. Determine if you are doing it. Magnetic information is originally information in which reflected light information is recorded on the magnetic layer, but the reflected light information is read, converted into a drive current for the magnetic head reflecting the signal, and recorded in the magnetic layer with a time delay. Therefore, even if the original signals are in phase, a phase difference is inevitably produced before they are recorded on the magnetic layer. However, as long as the magnetic information is information in which the reflected light information is recorded, the phase difference is constant and the periods must match. Conversely, if the magnetic information is information that does not reflect the reflected light information, the phase difference is not constant and the periods do not match, so it can be determined to be false.

Information obtained by reading may be determined immediately at the same time, or may be determined after being compared once through computation. Even if it is analog information, it can be judged after conversion to digital information. In addition, when the window opening 23 in FIG. 6 is partially applied to the hologram or diffraction grating 4 ′, the information of the hologram or diffraction grating in that part cannot be read accurately. It is also possible to set a criterion for determining true if partial matches.

As a base material, a PET film having a thickness of 25 μm, Lumirror 25T60 (manufactured by Toray Industries, Inc.) was used. On this surface, an ink having the following vapor deposition anchor layer ink composition was applied with a wire bar to a thickness of 1 μm, and then aluminum was vapor deposited by a vapor deposition method to a thickness of 40 nm. Further, an ink composed of a mask ink composition was provided at a thickness of 2 μm at intervals of 5 mm to form a mask layer. This was etched with a 2N aqueous sodium hydroxide solution for about 10 minutes to obtain a reflective layer.
(Vapor deposition anchor layer ink composition)
・ Vinyl chloride resin Solvain A (Nisshin Chemical Industry Co., Ltd.) 20 parts by weight ・ Isocyanate curing agent Duranate 24A100 (Asahi Kasei Co., Ltd.)
5 parts by weight ・ 75 parts by weight of methyl ethyl ketone / toluene (mask ink composition)
・ Vinyl vinyl chloride resin sorbine A (manufactured by Nissin Chemical Industry Co., Ltd.) 30 parts by weight ・ Cyclohexanone / isophorone 70 parts by weight

Next, the ink which consists of the following magnetic layer ink composition was printed on the back surface with the thickness of 15 micrometers with the wire bar, and the magnetic orientation was performed by the orientation magnetic field of 300 mT. This was aged at 60 ° C. for 72 hours to obtain the magnetic layer 3. The coercive force of the magnetic powder used this time was about 220 kA / m. The squareness ratio in the easy axis direction was 0.85.
(Magnetic layer ink composition)
・ Barium ferrite magnetic powder MC-127 (manufactured by Toda Kogyo Co., Ltd.) 25 parts by weight ・ Vinyl vinyl chloride resin sorbine A (manufactured by Nissin Chemical Industry Co., Ltd.) 10 parts by weight ・ Methyl ethyl ketone / toluene 65 parts by weight ・ Isocyanate curing agent Duranate 24A100 (Asahi Kasei Corporation)
5 parts by weight

  From the raw material thus obtained, the easy axis of magnetization was taken as the longitudinal direction, and the security thread was cut out by slitting to a width of 5 mm. The front and back of this security thread is shown in FIG. The reflective layers are provided at intervals of 5 mm. First, magnetic recording was performed on the entire magnetic layer in the direction of the left arrow shown in FIG. Next, the reflection layer is irradiated with a 635 nm semiconductor laser, the specular reflection is received by a photodetector, a recording current is passed through the magnetic head using the output as a switch, and light is incident on the photodetector on the back magnetic layer. Magnetic recording was performed in the direction of the right arrow 7 to obtain a security thread on which the same magnetic recording as in FIG. 7 was performed.

  Using this security thread, paper was made by hand so that the size of the window opening was 10 mm wide and 30 mm high, and was sufficiently dehydrated and dried to obtain a security paper. The final security paper size was 15 cm × 5 cm. For ease of reading the information on the front and back, the security thread was taken in the longitudinal direction of the security paper.

  Reading of the reflective layer was performed by irradiating a 635 nm semiconductor laser, placing a photodetector in the regular reflection direction, and connecting an oscilloscope to the output. For reading the magnetic layer, a magnetoresistive sensor MR-F-21 (manufactured by Nikkoshi Co., Ltd.) was placed on the back side of the security paper, and the output amplified 1000 times with an OP amplifier was connected to an oscilloscope.

Each output waveform is shown in FIG. From this output, two waveforms were obtained that were equally spaced and timed. It is considered possible to determine the authenticity by taking in this waveform.

(Comparative Example 1)
FIG. 13 shows the result of the measurement made with the oscilloscope except that no magnetic recording was performed on the magnetic layer. In this case, no output is obtained because there is no change in the magnetic field lines of the magnetic layer. Since there is no output, it can be clearly judged as false.

As a base material, a PET film having a thickness of 25 μm, Lumirror 25T60 (manufactured by Toray Industries, Inc.) was used. On this surface, an ink composed of the following diffraction grating layer ink composition was coated with a wire bar to a thickness of 2 μm, and then aluminum was deposited to a thickness of 40 nm by a vapor deposition method. Further, a diffraction grating pattern was formed on the aluminum deposition layer by using a stamper having a diffraction grating pattern of 1 μm with a grating interval of 5 mm. This was aged at 60 ° C. for 72 hours to cure the diffraction grating layer ink. Further thereon, an ink having the same composition as the diffraction grating layer ink composition was provided in a thickness of 1 μm and aged at 60 ° C. for 72 hours to form a protective layer.
Thus, a diffraction grating was obtained.
(Diffraction grating layer ink composition)
・ Acrylic polyol resin MCA4039 (manufactured by DIC Corporation) 30 parts by weight ・ Isocyanate curing agent Duranate 24A100 (manufactured by Asahi Kasei Corporation)
10 parts by weight ・ Methyl ethyl ketone / toluene 60 parts by weight

Next, an ink having the following magnetic layer ink composition was printed on the back surface by a screen printing method at a pattern thickness of 3 μm at intervals of 5 mm and aged at 60 ° C. for 72 hours to obtain a magnetic layer. The coercive force of the magnetic powder used this time was about 10 kA / m.
(Magnetic layer ink composition)
・ Magnetite magnetic powder MG-7000 (Mitsui Metal Mining Co., Ltd.) 15 parts by weight ・ Urethane-based screen ink medium SS16
(Toyo Ink Manufacturing Co., Ltd.) 70 parts by weight ・ Isocyanate curing agent Duranate 24A100 (Asahi Kasei Co., Ltd.)
15 parts by weight

  A security thread was cut out from the raw material thus obtained by slitting to a width of 5 mm. The state of the front and back of this security thread is shown in FIG. The diffraction grating on the surface can obtain diffracted light in the width direction. Both the diffraction grating and the magnetic layer are provided at intervals of 5 mm. Using this security thread, paper was made by hand so that the size of the window opening was 10 mm wide and 30 mm high, and was sufficiently dehydrated and dried to obtain a security paper. The final security paper size was 15 cm × 5 cm. Note that the security thread 1 was taken in the longitudinal direction of the security paper for easy reading of the information on the front and back.

  Reading of the diffraction grating was performed by irradiating a semiconductor laser of 635 nm from the normal direction, placing a photodetector at a direction of 40 degrees from the normal, and connecting an oscilloscope to the output. For reading the magnetic layer, a magnetoresistive sensor MR-F-21 (manufactured by Nikkoshi Co., Ltd.) was placed on the back side of the security paper, and the output amplified 1000 times with an OP amplifier was also connected to an oscilloscope.

  Each output waveform is shown in FIG. Although it can be determined from these output waveforms that the phases of the two signals are out of phase but the periods are the same, it is considered that this waveform can be taken in and the authenticity can be determined.

(Comparative Example 2)
FIG. 15 shows the result of measurement similar to that of the example except that the interval between the magnetic layers was changed to 3 mm and measured with an oscilloscope. In this case, since the phase and the period of the two signals are inconsistent, it can be determined to be false.
(Comparative Example 3)
FIG. 16 shows the result of manufacturing in the same manner as in Example 2 and measuring with an oscilloscope except that the magnetic layer was not provided. In this case, since there is no output of the magnetic layer, it can be clearly judged as false.

DESCRIPTION OF SYMBOLS 1 ... Security thread 2 ... Base material 3 ... Magnetic layer 4 ... Reflective layer 4 '... Hologram or diffraction grating 5 ... Reflection part 6 ... Non-reflection part 7 ... The surface of a security thread 8 ... The back surface of a security thread 9 ... Diffraction direction 11 ... Deposition anchor layer 12 ... Metal deposition layer 13 ... Mask layer 21 ... Security paper 22 ... Plain paper 23 ... Window opening part 31 ... Light incident on reflection part 32 ... Reflection light 33 from reflection part ... Injection on non-reflection part Light 34 ... Reflected light from non-reflecting part (not present)
35 ... Magnetic head 36 ... Magnetic information 37 ... Waveform of reflected light information from reflection layer 38 ... Waveform of magnetic information 39 ... Waveform of reflected light information from hologram or diffraction grating 40 ... Irradiation unit 41 ... Light receiving unit 42 ... Magnetic reading Part

Claims (7)

  A security thread comprising a hologram or a diffraction grating on one surface of a base material and a magnetic layer mainly composed of a magnetic material on the other surface.   A security characterized in that a reflective layer is provided on one surface of a substrate, a magnetic layer mainly composed of a magnetic material is provided on the other surface, and a part of the reflective layer is removed. thread.   3. The security thread according to claim 1, wherein information that is synchronized with the hologram, the diffraction grating, or the reflective layer is recorded in the magnetic layer.   3. The security thread according to claim 1, wherein the magnetic layer is provided in a pattern in a state of being synchronized with the hologram, the diffraction grating, or the reflective layer.   5. Information that can be converted into reflected light information by the same or an arbitrary algorithm as the reflected light information by the hologram, the diffraction grating, or the reflective layer is recorded on the magnetic layer. The security thread according to any one of the above.   7. A security sheet in which the security thread according to claim 1 is inserted.   The security thread according to any one of claims 1 to 5, or the security paper verification method according to claim 6, wherein the reflection is obtained by irradiating the hologram, the diffraction grating, or the reflective layer with light. A constant phase difference between the reflected light information obtained by receiving light (including diffracted light) and the signal converted by the same or an arbitrary algorithm and the signal reflecting the magnetic information recorded in the magnetic layer A verification method characterized in that authenticity determination is performed by determining the coincidence between a property and a period.

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