JP2006268469A - Authentication method for metameric image forming body, and metameric image forming body - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide forgery preventive printed matter and authentication method, having metamerism effect excellent in a mechanical authentication property. <P>SOLUTION: In this authentication method for a metameric image forming body produced by use of a metameric pair ink comprising a first ink and a second ink visually looking like the same color, a visible light area of a wavelength less than 650 nm is set as a first wavelength area, a visible light area of a wavelength not less than 650 nm and less than 780 nm is set as a second wavelength area, and a near infrared area of a wavelength not less than 780 nm is set as a third wavelength area to a reflectance characteristic of the metameric pair ink, arbitrary main wavelengths respectively selected from the first, second and third wavelength areas are acquired, and a difference between reflectance characteristics of the acquired main wavelengths and a previously stored difference between reflectance characteristics of the main wavelengths of a genuine article are compared to distinguish genuineness. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a machine discrimination method for printed matter using metameric ink that can be applied to valuables such as banknotes, passports, securities, cards, stamps, product tags, toll roads, various tickets, and the like. It relates to printed matter.

  With the recent development of digital devices such as scanners, printers, and color copies, it has become possible to easily make elaborate copies of precious printed matter. As one of the countermeasures, many methods using a metameric pair ink applying metamerism as a visual identification method have been tried. The method for visual recognition of precious printed matter using metameric pair ink utilized the characteristics that the ink looks the same color or looks different due to the type of light source to illuminate and the presence of a filter that transmits a specific wavelength. Is. Conventionally, a method of utilizing optical properties due to ink metamerism in printed matter that requires anti-counterfeiting technology has been used.

  As an image forming body using such a metameric property for anti-counterfeiting, a method for preventing forgery of an image forming body and an image forming body subjected to a forgery preventing measure are known. This is an anti-counterfeiting method and an image forming body formed by using two or more kinds of color materials having a metameric property so that a pattern can be recognized when viewed under a specific light source or a specific wavelength transmission filter. . In addition, it looks the same color when viewed with normal effects, but it uses two or more types of color materials having a metameric property so that the pattern can be recognized when viewed under a specific light source or a specific wavelength transmission filter. The anti-counterfeiting method and the image forming body are formed (for example, refer to Patent Document 1).

  In addition, the applicant assigns each of the metameric pair inks different near-infrared characteristics, and prints using the two types of metameric pair inks are reflected or transmitted in two wavelengths in the near-infrared region. As a true / false discrimination method and device for reading the image by voltage conversion, a mechanical discrimination method and device for true / false discrimination printed matter have been filed (for example, see Patent Document 2).

JP 54-159004 A JP 2000-293729 A

  However, in the image forming body subjected to the anti-counterfeiting method and the anti-counterfeiting measure of the image forming body described above, by visually observing the printed matter using the metameric pair ink using a difference in light source or a specific wavelength transmission filter, The color can be recognized differently, and cannot be used for machine authentication.

  The true / false discrimination printed matter mechanical discrimination method and apparatus described above are used for machine authentication, but the same reflectivity curve in the visible light region is used, and true / false discrimination in the near infrared region of 800 nm or more is performed. Machine authentication was performed. In recent years, azomethine-based pigments are commercially available as black pigments that transmit in the near-infrared region. By combining with carbon black and ITO that absorb in the near-infrared region, the reflectance curve of metameric pair inks in the near-infrared region. It has become easier to give different characteristics to the image, and there is room for improvement in machine authentication of precious printed matter to determine authenticity only in the near infrared region.

  In addition, the machine authentication method using the function of the near-infrared region of the ink makes the ink that absorbs infrared light invisible or concealed on the base material, and the characteristics are detected by the machine and the authenticity is recognized by the same color. However, IR pair inks having different reflectance curves and transmittances in the infrared region are known. However, the machine authentication method based only on the detection of the infrared region has become easier to analyze due to recent technological advancement, and it has become possible to produce printed matter having a similar metamerism effect. The fear of becoming.

  In addition, recent ink jet toners use pigment-based colorants to improve light resistance, and have the property of absorbing in the infrared region, and conventional dye-based toners are transparent in the infrared region. Therefore, it is possible to easily produce a reflectance curve and a transmittance characteristic approximated from the visible light region to the infrared region by using different printers. In view of the above current situation, the method for determining authenticity only in the infrared region is not perfect.

  In view of such a situation, the present invention is a metameric pair ink used for anti-counterfeit prints that exhibits a metamerism effect suitable for machine authenticity. In the visible light region having a wavelength of 400 nm or more and less than 780 nm, Furthermore, the same reflectance curve is shown in the near-infrared region having a wavelength of 780 nm or more and less than 2000 nm, which is the same color, and used in conventional machine discrimination, and a wavelength of 650 nm or more and less than 780 nm corresponding to a visible light region close to the near-infrared region. An image using a metameric pair ink in which a difference in reflectance curve is given to the ink at a specific wavelength, and one or more of the metameric pair inks are blended with a magnetic material that reflects or transmits in the infrared region. The formed body has a specific wavelength between 400 nm and less than 650 nm in the visible region, and 650 n The measurement points in two arbitrary wavelength ranges of 780 nm or more and less than 780 nm, the measurement points of an arbitrary wavelength range between 780 nm or more and less than 2000 nm in the near infrared region, and the presence / absence of magnetic characteristics or the difference in magnetic quantity are used for machine discrimination. Another object of the present invention is to provide a printed matter using a metameric pair ink that can be used and a method for determining authenticity.

  The present invention relates to a method for discriminating authenticity of a metameric image formed body produced using a metameric pair ink composed of a first ink and a second ink that appear to be the same color visually, and the reflection of the metameric pair ink With respect to the rate characteristic, the wavelength of visible light region less than 650 nm is the first wavelength region, the wavelength of visible light region is 650 nm or more and less than 780 nm is the second wavelength region, and the near infrared region wavelength of 780 nm or more is the third wavelength region. The arbitrary main wavelength selected from each of the first, second and third wavelength regions is acquired, and the difference in reflectance characteristics of the acquired main wavelength and the reflection of the genuine main wavelength stored in advance are acquired. This is a method for determining the authenticity of a metameric image forming body that determines authenticity by comparing the difference in rate characteristics.

  According to the present invention, there is provided a metameric image forming body, wherein at least one of the first ink and the second ink of the metameric pair ink has a magnetic property, and authenticity is discriminated from the magnetic property. This is a true / false discrimination method.

  According to the present invention, the authenticity of the metameric image forming body is characterized by acquiring at least one of the presence / absence of magnetism, the amount of magnetism, the magnetic detection voltage, and the magnetic detection waveform, and determining the authenticity. Is the method.

  In addition, the present invention is a metameric image forming body using a metameric pair ink composed of a first ink and a second ink that appear to be the same color by visual observation, wherein the first and second inks of the metameric pair ink are used. A first ink and a second ink obtained from an arbitrary dominant wavelength selected from a wavelength of less than 650 nm in the visible light region, a wavelength of from 650 nm to less than 780 nm in the visible light region, and a wavelength of 780 nm or more in the near infrared region; The metameric image forming body is characterized in that a difference in reflectance characteristics is provided at least at one or more of the reflectance characteristics at the dominant wavelength of the ink.

  Further, according to the present invention, the difference in reflectance between the first and second inks of the metameric pair ink is less than 10% in the wavelength of the visible light region of less than 650 nm and the dominant wavelength in the near infrared region of 780 nm or more. In the above-mentioned metameric image forming body, the difference in reflectance of an arbitrary dominant wavelength in the visible light region having a wavelength of 650 nm or more and less than 780 nm is 30% or more.

  Further, the present invention provides a color of a dioxazine-based color material or a cobalt chloride compound which is a condensate of chloranil and 3-amino-9-carbazole in either the first ink or the second ink of the metameric pair ink. A metameric image forming body characterized by containing a material.

  In addition, the present invention is a metameric image forming body characterized in that any one or more of the first ink and the second ink of the metameric pair ink has a magnetic property.

  Further, according to the present invention, at least one of the first ink and the second ink of the metameric pair ink is a near-infrared transmissive soft magnetic material, a near-infrared transmissive semi-hard magnetic material, or a near-infrared transmissive hard magnetic material. Or a near-infrared reflective soft magnetic material, a near-infrared reflective semi-hard magnetic material, or a near-infrared reflective hard magnetic material.

  Since there is a difference in reflectance in an arbitrary visible light region, and also in the presence or absence of magnetism and the amount of magnetism, an anti-counterfeiting effect can be expected for color copying and copying with a printer. Moreover, as a kind of ink, it can respond to any plate type such as offset ink, letterpress ink, gravure ink, intaglio ink, and screen ink.

  Measure the difference in reflectivity at any wavelength selected from the visible light region of 400 nm or more and less than 650 nm, the near infrared region of 780 nm or more, and the visible light region of 650 nm or more and less than 780 nm, and magnetic properties other than optical properties In addition, by using the method as the true / false discrimination means, it is possible to improve the machine authentication and to accurately discriminate true / false from the conventional measurements at two different wavelengths in the near infrared region.

  Since a printed matter having a special metamerism effect can be produced only by changing the ink material, the printing cost is almost the same as the conventional one and the cost performance is excellent.

  Embodiments of the present invention will be described. The printed matter in the embodiment of the present invention is produced by printing on a substrate using two or more kinds of inks, and can be visually recognized as the same color, but the visible light region of 400 nm or more and less than 650 nm and the vicinity of 780 nm or more. It has a metamerism effect in which the reflectance in the infrared region is the same, and a different reflectance curve is expressed at 650 nm or more and less than 780 nm. The difference is less than 10% at 780 nm or more, and they have substantially the same reflectance (see FIG. 2).

  For the production of printed matter, a metameric ink using a dioxazine-based or cobalt chloride compound such as a condensate of chloranil and 3-amino-9-carbazole, which is a color material that transmits at 600 nm or more, as a color material, and this metameric Use the same color as the ink, and the same color pair ink that does not have a metameric effect.

Also, at least one of the paired inks is an ink containing an oxide magnetic material having a property of transmitting light in the infrared region and having a remanent magnetization of 25 to 35 emu / g. The true discrimination print using this pair ink (see FIG. 1) is irradiated with three light sources that have passed through bandpass filters with center wavelengths of 550 nm, 725 nm, and 860 nm, for example, and the difference in reflectance is read and the amount of change This is a method for determining authenticity of reading by using an MR (Magneto Resistance) magnetic sensor for reading the magnetic field, a differential sensor for reading the magnetic quantity, or the like.
Note that the center wavelength referred to here is the center having a range of about ± 5 nm at a half value (a value of 50%) of the transmittance of 100%. In the present embodiment, since the band pass filter is used, the center wavelength is the center of the range of about ± 5 nm, but this is not limited depending on the filter used.

  In the present invention, as shown in FIG. 3, the reflectance curve of the metameric pair ink has a wavelength of less than 650 nm in the visible light region as the first wavelength region, and a wavelength of from 650 nm to less than 780 nm in the visible light region. The wavelength region of 2 and the wavelength of 780 nm or more in the near infrared region were set as the third wavelength region.

  The authenticity determination method will be described with reference to the flowchart shown in FIG. In the first step, for example, light having a central wavelength of 550 nm of the first wavelength is irradiated from the light source, and the first print region X and the second print region Y are determined from the obtained reflectance of the main wavelength of the first wavelength. The difference is measured, and if there is a difference exceeding the allowable value in the measured value, it is judged as a counterfeit product. If the difference is within the allowable value of 10% or less, the process proceeds to the second step (S1). In the second step, the light having the center wavelength of 725 nm of the second wavelength is irradiated, and from the obtained reflectance of the main wavelength of the second wavelength, the first printing region X and the second printing region Y are similarly detected. The difference is measured, and if the difference is less than the set allowable value, it is judged as a counterfeit product, and if the measured value has a difference of 30% or more, the process proceeds to the third step (S2). Subsequently, in the third step, the third wavelength light having the center wavelength of 860 nm is irradiated, the difference in the reflectance of the main wavelength of the acquired third wavelength is read, and the first print region X and the second print The difference in the area Y is measured, and if the measured value exceeds the allowable value, it is determined to be a counterfeit product. If the difference is within the allowable value of 10% or less, the process proceeds to the fourth step (S3). In addition to authenticity determination based on the difference in reflectance so far, magnetic characteristics are detected in the fourth step. In the fourth step, the magnetic characteristics such as the presence or absence of magnetism or the difference in magnetic quantity are inspected, and the determination is made appropriately according to the set value to determine true / false. For example, in the case of a printed matter in which “true” is set to indicate that there is a difference in magnetic quantity, a product having no difference is determined to be a counterfeit product, and a product having a difference is finally determined to be a genuine product (S4). ).

  Here, generally, when magnetic materials are classified based on magnetic properties, they are roughly classified into soft magnetic materials and hard magnetic materials. In this specification, soft magnetic materials, semi-hard magnetic materials and hard magnetic materials are classified according to the characteristics of magnetic properties. Subdivide and define. The soft magnetic material is a magnetic material represented by nickel ferrite, manganese zinc ferrite, etc., having a high magnetic permeability, a small residual magnetization, and a coercive force of less than 1 A / m to several kA / m. The semi-hard magnetic material refers to a magnetic material having a certain degree of residual magnetization and a coercive force of less than 20 kA / m, typified by magnetite, meghematite, and cobalt-based iron oxide. The hard magnetic material refers to a magnetic material having a large remanent magnetization typified by permanent magnets such as arconi-based magnets and barium helite and having a large coercive force and 20 kA / m or more.

  As a method for reading magnetic characteristics, an external magnetic field is applied to a printed matter using ink containing a magnetic material (hereinafter referred to as a magnetic printed matter) to retain the magnetic flux, and the magnetic field is removed after removing the external magnetic field. Using a magnetic sensor to which a bias magnetic field is applied according to the holding power of the contained ink, for example, an MI sensor (magneto impedance), when the target magnetic material-containing printed matter passes, the output from the magnetic sensor is not output. There is a way. This technology discriminates that a genuine magnetic material is used based on the residual magnetic flux density after the magnetic sensor gives magnetism to the magnetic printed matter and the magnetic field is removed. By applying magnetic bias to the printed material, removing the magnetic field, applying an appropriate bias magnetic field and measuring using a magnetic sensor, the magnetic discriminating reading method enables output when the magnetic ink is authentic. is there.

  Various magnetic sensors magnetize a magnetic material on a printed matter with a magnetic field (bias) of a certain magnitude, and detect a magnetic field response corresponding to the magnetic characteristics of the magnetic material. The magnitude of the bias magnetic field and the detection mechanism vary depending on the type of sensor. Sensors used for magnetic reading are broadly classified into those that detect changes in magnetic flux using electromagnetic dielectrics and those that directly detect magnetic fields using physical properties of specific elements such as magnetoresistance and skin effect of thin films. Can do. The detected waveform can be divided into a differential type corresponding to the amount of change in magnetic flux and a quantitative type corresponding to the density of the print area. The ring-type sensor or MR sensor detection waveform becomes differential, the ring-type sensor is a method of detecting a change in magnetic flux by electromagnetic induction, and the MR sensor is a method of using the magnetoresistance change of the InSb thin film. As a sensor for reading the magnetic quantity, there are a differential sensor and an MI sensor. The detection waveform of the differential sensor is quantitative, and is a method in which an alternating magnetic field is applied to detect a change in resistance of the detection magnetic circuit due to magnetization of the detected object and eddy current. Although the MI sensor also has a quantitative detection waveform, it is a method of detecting a magnetic field using the magnetic impedance effect of the magnetic thin film.

  Hereinafter, examples of the authenticity determination method and production method for printed matter having metamerism characteristics and magnetism according to the present invention will be described in detail with reference to the drawings. However, the content of the present invention is limited to these examples. It also includes technical categories that are easily analogized.

Example 1
FIG. 1 shows a schematic diagram of the authenticity printed matter A1 of the present invention. A first printing region X is formed on the paper 1 of the authenticity printed matter A1 using the first ink a containing a dioxazine-based color material such as a condensate of chloranil and 3-amino-9-carbazole, and is visible In the light region, the second printing is performed using the second ink b which has the characteristic of visually observing the same color and transmitting light in the infrared region and containing an oxide magnetic material having a residual magnetization of 25 to 35 emu / g. The pattern 4 in which the region Y is formed is printed. A reflectance curve of the pattern 4 at 200 nm to 2000 nm is shown in FIG. On the printed pattern 4, three light sources that have passed through bandpass filters having a center wavelength of 550 nm as a first wavelength, a center wavelength of 725 nm as a second wavelength, and a center wavelength of 860 nm as a third wavelength are sequentially provided. Irradiate and read the reflectance. As shown in FIG. 3, the reflectance curve at 400 nm to 1000 nm in which the difference in reflectance curve is noticeable, the first printing region X and the second printing region Y have no difference in reflectance curve at the first wavelength. At the second wavelength, since the first printing region X contains a dioxazine-based color material such as a condensate of chloranil and 3-amino-9-carbazole, it exhibits a high reflectance of 35% or more. In the second print region Y, a remarkably high reflectance curve as in the first print region X cannot be obtained, and a difference of 25 to 30% occurs as a difference in reflectance. Further, at the third wavelength, the printed matter has almost no reflectance curve difference of less than 10%.

  FIG. 4 shows the detection voltage when the MR magnetic sensor for detecting the presence or absence of magnetism is scanned in the direction of the arrow in FIG. A magnetic waveform is obtained in the second print region Y, but no magnetic waveform is obtained on the first print region X. Similarly, the detection voltage when scanning in the direction of the arrow in FIG. 1 with a differential sensor that detects the amount of magnetism is as shown in FIG. 5 in the first printing region X using the first ink a. In the second printing region Y using the second ink b, it is not detected as magnetism, and can be detected as a magnetic amount by voltage.

  As described above, the presence or absence of magnetism or the amount of magnetism is detected on the pattern 4 of the authenticity discrimination printed matter A1 by the reflectance curves of three wavelengths and the magnetic sensor, thereby reflecting the three wavelengths of genuine products stored in advance. This is a method of determining authenticity by comparing the rate curve and the value of the presence or absence of magnetism or the amount of magnetism detected by a magnetic sensor, and its flowchart is shown in FIG. Based on the flowchart of FIG. 6, the authenticity determination printed matter A1 can be accurately determined by detecting the optical characteristics from the first step to the third step and the magnetic characteristics of the fourth step. In addition, as a method for determining the machine, even if the sensors are fixed and the authenticity determination printed matter A1 travels, the light source, the light receiving sensor, and the magnetic sensor including the filter may travel.

The ink composition of Example 1 is shown below. The colored pigment here is a general pigment such as an offset ink. The first ink a and the second ink b are inks that appear to be the same color visually.
First ink a (purple)
Colored pigment (yellow) 5 parts by weight Colored pigment (red) 10 parts by weight Colored pigment (black) 0.5 part by weight Dioxazine pigment 10 parts by weight Varnish 67.4 parts by weight Desiccant 0.1 part by weight Auxiliary agent 7 parts by weight Second ink b (purple)
Color pigment (red 1) 10 parts Color pigment (red) 10 parts Color pigment (blue) 5 parts Color pigment (black) 0.5 parts Magnetic material 5 parts Varnish 61.4 parts by weight Desiccant 0. 1 part by weight Auxiliary agent 8 parts by weight

(Comparative Example 1)
Here, the authenticity determination printed matter A1 described in the first embodiment is used and compared according to the authenticity determination flowchart of FIG. A first printed area using a replica X of the pattern 4 of FIG. 1 of the same color visually produced by a printer using dye-type ink, and the first ink a and the second ink b shown in FIG. FIG. 7 shows the reflectance curve of the authenticity discrimination printed matter A1 at 400 nm to 1000 nm in X and the second printing region Y. As shown in FIG. 7, there is no difference at the first wavelength of 550 nm, but there is a difference of 30% or more in the reflectance at the third wavelength of 860 nm, which is judged to be a counterfeit product from the flowchart of FIG. Is done.

(Comparative Example 2)
In addition, a duplicate Y of the pattern 4 of the same color visually produced by a printer using pigment-type ink, and the first printing region X using the first ink a and the second ink b shown in FIG. And the reflectance curve of the authenticity discrimination | determination printed matter A1 in 400 nm-1000 nm of the 2nd printing area | region Y is shown in FIG. As shown in FIG. 8, the reflectance curve of the pattern 4 produced by the printer using the second ink b and the pigment type ink is the same reflectance curve. However, in comparison with the first ink a, there is a difference of 30% or more at the second wavelength of 725 nm, and the first printing area X and the second printing area Y in FIG. Are considered counterfeit because they have the same reflectance curve.

(Comparative Example 3)
The first ink a was duplicated with a dye-type printer, and the second ink b was duplicated with a pigment-type printer. Reflectance at 400 nm to 1000 nm of the duplicate Z of the pattern 4 of the same color and the authenticity discrimination printed matter A1. The curve is shown in FIG. As shown in FIG. 9, the difference between the reflectance curves at three wavelengths of the replica Z is almost the same as that of the genuine authenticity discrimination printed matter A1, and if only the reflectance curve is used as a determination element, It will be judged. However, since the second ink b contains a magnetic pigment, the first ink a (first printing region X) and the second ink b (second printing) as shown in FIG. Since no magnetism is detected in region Y), it is determined to be a counterfeit product.

(Example 2)
The first ink a containing a dioxazine-based color material such as a condensate of chloranil and 3-amino-9-carbazole and an oxide magnetic material having a remanent magnetization of 50 to 70 emu / g on the sheet 1 of the authenticity printed matter A1. ′ Is used to form the first print region X, and in the visible light region, the oxide magnetic material has a characteristic of transmitting the light in the infrared region and the same color under visual observation and having a residual magnetization of 25 to 35 emu / g The pattern 4 in which the second printing region Y is formed using the second ink b ′ containing the is printed.

  The printed pattern 4 is sequentially irradiated with three light sources that have passed through bandpass filters having a first wavelength of 550 nm and a second wavelength of 725 nm and a third wavelength of 860 nm, and the reflectance is determined. read.

  The first printing region X and the second printing region Y have no difference in reflectance at the first wavelength, and the dioxazine-based material such as a condensate of chloranil and 3-amino-9-carbazole in the region at the second wavelength. Since it contains an oxide magnetism that transmits light in the color material and the infrared region, it exhibits a high reflectance, but a high reflectance curve cannot be obtained in the second printing region Y, and the reflectance is 20-30. % Difference occurs. Further, at the third wavelength, the printed matter has almost no reflectance difference of less than 10%. In addition, by scanning in the direction of the arrow in FIG. 1 with an MR magnetic sensor that reads the amount of change. Since the magnetic strengths of the first ink a ′ and the second ink b ′ are different, the authenticity determination is performed by detecting the three-wavelength reflectivity and magnetic sensor on the pattern of the authenticity determination printed matter. . In addition, as a method for determining the machine, a sensor may be fixed and an authenticity determination printed material may travel, or a light source, a light receiving sensor, and a magnetic sensor including a filter may travel.

The ink composition of Example 2 is shown below.
1st ink a '(purple)
Color pigment (yellow) 3 parts Color pigment (red) 8 parts Color pigment (black) 0.5 parts Dioxazine pigment 10 parts Magnetic material 5 parts Varnish 68.4 parts Drying agent 0.1 parts by weight Auxiliary agent 10 parts by weight second ink b '(purple)
Color pigment (red 1) 10 parts Color pigment (red 2) 10 parts Color pigment (blue) 3 parts Color pigment (black) 0.5 parts Magnetic material 3 parts Varnish 63.4 parts by weight Desiccant 0 .1 part by weight Auxiliary agent 10 parts by weight

(Example 3)
Dioxazine-based color material such as chloranil and 3-amino-9-carbazole condensate and oxide magnetism having a remanent magnetization of 25 to 35 emu / g and ferrite having a remanent magnetization of 1 to 15 emu / g The first printing region X is formed by using the first ink a ″ containing, and has a characteristic of transmitting the light in the infrared region and the same color in the visible light region with the same color under visual observation, and having a residual magnetization of 25 to 35 emu. The pattern 4 in which the second print region Y is formed is printed using the second ink b ″ containing the oxide magnetic body having / g and the gamma iron oxide having the remanent magnetization of 1 to 15 emu / g.

  The printed pattern 4 is sequentially irradiated with three light sources that have passed through a bandpass filter having a first wavelength of 550 nm, a second wavelength of 725 nm, and a third wavelength of 860 nm, and the reflectance is determined. read.

  The first printing region X and the second printing region Y have no difference in reflectance curve at the first wavelength, and the dioxazine such as a condensate of chloranil and 3-amino-9-carbazole is present in the region at the second wavelength. Since it contains an oxide magnetism that transmits light in the infrared region and a coloring material, a high reflectance curve is shown, but a high reflectance curve cannot be obtained in the second printing region Y. A difference of 20-30% occurs. Further, at the third wavelength, the printed matter has no difference in reflectance curve. In addition, by scanning in the direction of the arrow in FIG. 1 with an MR magnetic sensor that reads the amount of change. Since the magnetic strengths of the first ink a ″ and the second ink b ″ are different, the authenticity determination is performed by detecting the pattern 4 of the authenticity determination printed matter A1 with the reflectance curves of three wavelengths and the magnetic sensor. Is the method. In addition, as a method for determining the machine, the authenticity determination printed matter A1 may travel with the sensors fixed, or the light source, the light receiving sensor, and the magnetic sensor including the filter may travel.

The ink composition of Example 3 is shown below.
First ink a ″ (purple)
Color pigment (yellow) 3 parts by weight Color pigment (red) 8 parts by weight Color pigment (black) 0.5 parts by weight Dioxazine pigment 10 parts by weight Magnetic material 1 3 parts by weight Magnetic material 2 3 parts by weight Varnish 64.4 parts by weight Desiccant 0.1 part by weight Auxiliary agent 10 part by weight Second ink b ″ (purple)
Color pigment (red 1) 10 parts Color pigment (red 2) 10 parts Color pigment (blue) 3 parts Color pigment (black) 0.1 parts Magnetic material 1 3 parts Magnetic material 4 3 parts Varnish 60 .8 parts by weight Desiccant 0.1 parts by weight Auxiliary agent 10 parts by weight

It is the schematic of the authenticity determination printed matter in this invention. It is an example of the graph of the spectral reflectance curve in 200 nm-2000 nm of the authenticity determination printed material in this invention. It is an example of the graph of the spectral reflectance curve in 400 nm-1000 nm of the authenticity determination printed matter in this invention. It is an example of the magnetic detection graph by MR sensor of the authenticity determination printed matter in this invention. It is an example of the magnetic detection graph by the differential type sensor of the authenticity determination printed matter in this invention. It is a truth determination flowchart in the Example of this invention. 6 is a graph of a reflectance curve in Comparative Example 1 of Example 1. 10 is a graph of a reflectance curve in Comparative Example 2 of Example 1. 10 is a graph of a reflectance curve in Comparative Example 3 of Example 1. 10 is a magnetic detection graph by an MR sensor in Comparative Example 3 of Example 1.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Paper 4 Printing pattern A1 Authenticity discrimination | determination printed matter X The 1st printing area Y by the 1st ink a The 2nd printing area Z by the 2nd ink b The reproduction by the comparative example with this invention

Claims (8)

A method for determining the authenticity of a metameric image formed body produced by using a metameric pair ink composed of a first ink and a second ink that appear to be the same color visually,
With respect to the reflectance characteristics of the metameric pair ink, a wavelength of less than 650 nm in the visible light region is the first wavelength region, a wavelength of the visible light region is not less than 650 nm and less than 780 nm is the second wavelength region, and a wavelength in the near infrared region is 780 nm. The above is the third wavelength region, an arbitrary main wavelength selected from each of the first, second and third wavelength regions is acquired, and the difference in reflectance characteristics of the acquired main wavelength is stored in advance. A method for determining the authenticity of a metameric image forming body, wherein the authenticity is determined by comparing the difference in reflectance characteristics at the main wavelength of a genuine product. 2. The metameric image formation according to claim 1, wherein at least one of the first ink and the second ink of the metameric pair ink has a magnetic characteristic, and authenticity is determined from the magnetic characteristic. How to determine the authenticity of the body. 3. The metameric image forming body according to claim 1, wherein the magnetic property is obtained by determining at least one of presence / absence of magnetism, a magnetic amount, a magnetic detection voltage, and a magnetic detection waveform, and determining whether the magnetic property is true or false. Authenticity discrimination method. A metameric image forming body using a metameric pair ink composed of a first ink and a second ink that appear to be the same color visually,
The first ink and the second ink of the metameric pair ink may be any one selected from a wavelength of less than 650 nm in the visible light region, a wavelength of from 650 nm to less than 780 nm in the visible light region, and a wavelength of 780 nm or more in the near infrared region. A metameric image characterized by having a difference in reflectance characteristic at least at one or more principal wavelengths among the reflectance characteristics of the principal wavelengths of the first ink and the second ink obtained from the principal wavelength. Formed body. The first ink and the second ink of the metameric pair ink are visible with a difference in reflectance of less than 10% at an arbitrary dominant wavelength of a wavelength of less than 650 nm in the visible light region and a wavelength of 780 nm or more in the near infrared region. The metameric image forming body according to claim 4, wherein a difference in reflectance at an arbitrary principal wavelength of a wavelength of 650 nm or more and less than 780 nm in the optical region is 30% or more. Either the first ink or the second ink of the metameric pair ink contains a dioxazine-based color material or a cobalt chloride compound color material, which is a condensate of chloranil and 3-amino-9-carbazole. The metameric image forming body according to claim 4 or 5, 7. The metameric image forming body according to claim 4, wherein at least one of the first ink and the second ink of the metameric pair ink has a magnetic property. One or more of the first ink and the second ink of the metameric pair ink is a near-infrared transmissive soft magnetic material, a near-infrared transmissive semi-hard magnetic material, a near-infrared transmissive hard magnetic material, or a near-infrared light. 8. The metameric image forming body according to claim 4, comprising any one of a reflective soft magnetic material, a near-infrared reflective semi-hard magnetic material, and a near-infrared reflective hard magnetic material.

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