JP4461234B2 - Authentic printed material - Google Patents

Description

  The present invention relates to a printed matter capable of authenticating authenticity applied to valuables such as banknotes, passports, securities, cards, stamps, product tags, toll roads and various valuable tickets.

  With the recent development of digital devices such as scanners, printers, and color copiers, it has become possible to easily produce 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 of visual discrimination of precious printed matter using metameric pair ink utilized the characteristic that the ink looks the same color or looks different due to the type of illumination light source and the filter that transmits a specific wavelength. Is. In the printed matter that requires anti-counterfeiting technology, a method of utilizing the optical characteristics due to the ink metamerism is conventionally performed.

  Usually, a printed matter printed with colored metameric pair ink has two wavelengths, a wavelength region A which is a visible total wavelength of 400 to 700 nm and a wavelength region B which is a predetermined wavelength transmitted by a predetermined filter or the like to be used. Observed in the area.

  The printed matter A1 shown in FIG. 1A forms a visible image 2 on the substrate 1, and the visible image 2 is printed with the first region 3 printed with the first ink and the second ink. 2 regions 4. When the printed matter A1 is observed with the naked eye under normal light such as sunlight, fluorescent light or incandescent light bulb, the first region 3 and the first region 3 printed with the first ink as shown in FIG. The second region 4 printed with the second ink is visually recognized in the same color, and only the visible image 2 can be confirmed. When the printed matter A1 is observed with the naked eye through a predetermined filter or the like, as shown in FIG. 1C, the first region 3 printed with the first ink and the second printed with the second ink are used. Since the color of the region 4 is visually recognized differently, it can be confirmed as a latent image. The printed matter A1 is judged to be genuine when there is a color difference between the first region 3 and the second region 4 through the predetermined filter 10 or the like with respect to the visible image 2, and when there is no color difference. Judged to be fake.

  Further, as a method for determining the authenticity of a printed matter using another metameric pair ink, there is a method using a change in contrast between the pair inks. In this method, since the specific wavelength region is set to a region limited to a range of about several tens of nanometers, the hue changes only slightly, but there is a difference in reflection and absorption characteristics in the specific wavelength region between the paired inks. Since it appears more conspicuously, only the density of the first region 3 in FIG. 1 is reduced, the second region 4 in FIG. 1 is emphasized, and the second region 4 appears to appear as a latent image. As described above, there is also a method for authenticating whether a latent image appears through a filter and performing authenticity determination.

  In any case, in each method of authenticating the presence or absence of a hue change or the appearance of a latent image, authenticity determination using a metameric pair ink can be performed by measuring differences in ink reflection and absorption characteristics in a specific wavelength region. It is what you use.

  For example, it looks the same color under normal light such as sunlight, fluorescent light or incandescent light bulb, but it can be viewed under a light source having a predetermined spectral energy distribution, through a predetermined filter, or passed through a predetermined filter. An image forming body characterized in that a pattern is formed on a substrate so that a pattern can be observed in contrast to each other by two kinds of colorants having a metameric property that one looks like a different hue when viewed under bright light Is disclosed (see Patent Document 1).

  In addition, the present applicant assigns metameric pair inks with different near-infrared characteristics, and prints using the two types of metameric pair inks can reflect or transmit light of two different wavelengths in the near-infrared region. An application has been filed for a true / false discrimination method and apparatus for reading in voltage conversion (see Patent Document 2).

Japanese Examined Patent Publication No. 60-58711 (page 1-4, FIG. 1-11) Japanese Patent No. 3709539 (page 1-6, FIG. 1-6)

  However, the printed matter printed with the conventional metameric pair ink is generally printed with a solid printing pattern when authenticating the presence or absence of a hue change or a latent image, and FIG. As shown in the figure, the latent image is given by using a so-called "extract" configuration in which a part of the visible image is blanked and the latent image is superposed and replaced with the blanked portion. Is almost. This is because multiple colors are not used, so the color is poor.In addition, there is a possibility that the latent image embedded in the visible image may be viewed under normal light, and there is no degree of design freedom. Below, a visible image that looks the same color and a latent image that appears when observed through a predetermined filter or the like are simple characters or marks. That is, there is no one that forms a visible image having a density gradation or a latent image having a density gradation. Japanese Patent Publication No. 60-58711 and Japanese Patent No. 3709539 do not describe the formation of density gradation.

  Assuming that the visible image 2 printed with the metameric pair ink, which is visually recognized under normal light, is used for the printed material using the metameric pair ink, at least two images, not just the solid image. In the case of the printed matter A2 having two density gradations, for example, a density gradation as shown in FIG. 2A, a highlight area, a halftone area, and a shadow area, the second area 4 appears through a predetermined filter 10 or the like. There is a problem that the visibility of the latent image consisting of is inferior as shown in FIG. This means that the gradation of the visible image 2 needs to be reflected in the latent image composed of the second region 4 in order to express the gradation in the visible image 2 that is visually recognized under normal light. For this reason, when the image is observed through a predetermined filter 10 or the like, the gradation of the visible image 2 appears in the latent image formed of the second region 4, and the latent image formed of the second region is light. A region is formed and the visibility is inferior. In addition, the visible image 2 itself is often changed to such an extent that the gradation representation area is slightly lost when the filter is passed through, so that the gradation of the visible image 2 itself appears to the extent that it can be visually observed. Mixing with the latent image composed of the region 4 is also one of the causes of poor visibility of the latent image when the gradation is given to the visible image 2.

  An object of the present invention is to solve such a conventional problem. Under visible light, a plurality of first areas and second areas are alternately arranged adjacent to each other. A visible image having a density gradation in which the third region is arranged by hair removal is visually recognized, and further, under visible light, the third region is concealed by the second region, and is a latent image composed of the third region. Is in a state where it is difficult to be visually recognized or is not visually recognized. When observed with the naked eye through a predetermined filter or the like, the latent image formed of the third area is visually recognized, and the latent image does not reflect the density gradation of the area having the density gradation visible under visible light. In addition, since the latent image formed of the third area is visually recognized with a clear density difference from the first area and the second area, it is possible to easily determine whether the image is true or false. Further, it is possible to give density gradation to the latent image composed of the third region as needed, and there is no design restriction.

  An object of the present invention is to propose a printed material printed with a metameric pair ink having the above-described gradation image and capable of authenticating authenticity.

  In the present invention, a plurality of first regions and second regions are alternately arranged adjacent to each other on the base material, and a third region is arranged in the second region by tweezers to have a density gradation. A visible image is formed, an image having a density gradation is formed by the first region, a latent image is formed by the third region, and the second region is a camouflaging region of the latent image, The first region and the second region are printed with a first printing ink, the third region is printed with a second printing ink, and the spectral reflection of the first printing ink and the second printing ink. The rate is approximated in the range of the first wavelength in the visible region, and the printed matter is printed with a metameric pair ink having a different value in the second wavelength range in the visible region. It is.

  Further, the halftone dot area ratio of the visible image having the density gradation of the present invention is formed at 40 to 80% or less, the halftone dot area ratio of the latent image is formed at 40% or less, and the camouflage region The halftone dot area ratio is a printed matter capable of authenticating authenticity, characterized by being formed at 40% or less.

  Moreover, the integral value of the spectral reflection spectrum between 640-700 nm of the said 1st printing ink of this invention has 2 times or more of the integral value of the spectral reflection spectrum between 640-700 nm of the said 2nd printing ink. The integral value of the spectral reflection spectrum between 400 and 600 nm of the first printing ink is substantially the same as the integral value of the spectral reflection spectrum between 400 and 600 nm of the second printing ink. It is a printed matter that can be falsely identified.

  In addition, the present invention is a printed matter capable of authenticating authenticity, wherein the latent image has a density gradation.

  According to the present invention, it is possible to obtain a printed material having a gradation image that can be applied to a valuable product printed with a metameric pair ink that is not restricted by a design, and that has a gradation image. Of course, it can be applied to printed materials other than valuables.

  A visible image having a density gradation is visually recognized on the authenticity determination printed matter under visible light. Further, under visible light, the latent image is in a state where it is difficult to see or not visible. However, when observed with the naked eye through a predetermined filter or the like, the latent image is visually recognized. The latent image does not reflect the density gradation of the area having the density gradation, and the latent image is visually recognized with a clear density difference between the latent image and other areas. Therefore, it is possible to easily determine whether or not the latent image is visually recognized, and to determine whether the latent image is true or false.

  The second region and the third region formed with the metameric pair ink are paired with each other, and the concealability of the latent image under visible light is improved as compared with the conventional case by making the overall density constant. Further, by appropriately setting the lowest halftone dot area ratio and the highest halftone dot area ratio of the first region, the second region, and the third region, the concealability of the latent image under visible light is improved, When observed with the naked eye through a predetermined filter or the like, the latent image is clearly visible.

  Further, it is possible to give density gradation to both the visible image and the latent image. Further, a camouflage pattern is formed on a visible image having a density gradation with at least one color ink (for example, magenta ink and / or yellow ink) having a high spectral reflectance between 640 and 700 nm, and a plurality of colors. And the concealability of the latent image under visible light can be improved.

  The best mode for carrying out the present invention will be described with reference to the drawings. However, the present invention is not limited to the embodiments described below, and includes various other embodiments within the scope of the technical idea described in the claims.

  Usually, an image composed of a metameric pair ink is observed in two wavelength regions, a wavelength region A having a visible total wavelength of 400 to 700 nm and a wavelength region B having a predetermined wavelength transmitted by a predetermined filter to be used. The The printed matter capable of authenticating in the embodiment of the present invention is produced by printing on a substrate using two or more kinds of ink.

  FIG. 3 (a) shows a printed matter B that can be determined authenticity. An image having a density gradation is formed in a first halftone area of m × m pixels, and a latent image and a camouflage area that hides the latent image are formed in a second halftone area of n × n pixels. . This special halftone dot configuration is obtained by combining the technique for directly defining two types of halftone dot data in the Postscript halftone dot generation method and the two types of halftone dot images proposed in Japanese Patent Laid-Open No. 2001-205917. It is generated by an image processing method that is uniformly arranged on the top.

  As shown in FIG. 3 (a), a plurality of first regions 2 and second regions 3 are alternately arranged adjacent to each other on the base material 1, and the third region 4 is tipped in the second region 3. A visible image 5 having a density gradation is formed by arranging them together. In this hair removal, the third region 4 is formed in the non-printing region 3a of the second region 3 as shown in FIG. Furthermore, as shown in FIG. 4, the position where the third region 4 is formed in the non-printing region 3a of the second region 3 is not particularly limited. Further, as shown in FIG. 5, the boundary between the second region 3 and the third region 4 is printed without overlapping as shown in FIG. 5A, or as shown in FIG. 5B. Alternatively, the second region 3 and the third region 4 may have a region 6 in which a part thereof overlaps. In the partially overlapped region 6, the third region 4 may be printed on the second region, or the second region 4 may be printed on the third region. In this case, it is preferable to adjust the density such as gradation in the overlapping region of one or both of the second region 3 and the third region 4. Further, the first region 2 and the second region 3 are alternately adjacent to each other here, but the regions themselves are adjacent to each other, but an image having a density gradation is formed in the first region 2. Therefore, large and small halftone dots are generated, and areas where the halftone dots of the first region 2 and the second region 3 are not in contact with each other are generated.

  Next, the sizes of the first region 2 and the second region 3 will be described. In FIG. 3, a plurality of sets of one first region 2 and one second region 3 adjacent to the first region 2 are arranged, and the periphery of the second region 3 is formed by the plurality of first regions 2. The first region 2 is surrounded and has a larger area than the second region 3, and the third region is formed in the second region 3 by hair removal. The present invention is not limited to this, and a plurality of sets of one first region 2 and one second region 3 adjacent to the first region 2 are arranged as shown in FIG. The first region 2 is surrounded by a plurality of second regions 3, and the second region 3 has a larger area than the first region 2, and the second region 3 includes a third region. These regions may be formed by tapping. Further, as shown in FIG. 6B, a plurality of sets of one first region 2 and one second region 3 adjacent to the first region 2 are arranged as shown in FIG. 6A. The first region 2 is surrounded by a plurality of second regions 3, the second region 3 is surrounded by a plurality of first regions 2, and the first region 2 is a second region The area may be the same as that of the region 3, and the third region may be formed in the second region 3 by tapping.

  As shown in FIG. 7, an image 7 having a density gradation is formed by the first region 2, a latent image 8 is formed by the third region 4, and the second region 3 is a camouflaged region of the latent image 8. 9

  The image 7 having the density gradation composed of the first region 2 and the camouflaged region 9 composed of the second region 3 are made of the first printing ink, and the latent image composed of the third region 4 is made of the second printing ink. Printed.

  The relationship between the first printing ink and the second printing ink will be described. The spectral reflectances of the first printing ink and the second printing ink are approximated in the first wavelength range in the visible region, and are different values in the second wavelength range in the visible region. That is, the first printing ink and the second printing ink have a relationship of metameric pair ink. Further, the integral value of the spectral reflection spectrum between 640 and 700 nm of the first printing ink has more than twice the integral value of the spectral reflection spectrum between 640 and 700 nm of the second printing ink. The integral value of the spectral reflection spectrum between 400 and 600 nm of the ink is preferably substantially the same as the integral value of the spectral reflection spectrum between 400 and 600 nm of the second printing ink.

  FIG. 8 is an example of a spectral reflectance curve of the first printing ink and the second printing ink that are the metameric pair inks used in the present invention. As shown in FIG. 8, the relationship between the spectral reflectances of the first printing ink and the second printing ink is designed to produce a spectral reflectance difference of 30% or more between 640 to 700 nm, and 20% at 400 to 600 nm. The first printing ink and the second printing ink are produced with a design that produces the following spectral reflectance difference. The first printing ink and the second printing ink having the spectral reflectance curve shown in FIG. 8 are tea-based color inks. However, in the present invention, the description is given using a metameric pair ink of tea color, but the metameric which is excellent in color matching under normal light and excellent in color difference in a specific wavelength range. If it is assumed that pair ink is used, there is no restriction on the color.

  The relationship between the first printing ink and the second printing ink, which are the metameric pair inks shown in FIG. 8, is designed so that a large difference occurs in the spectral reflectance of 640 nm or more, and the wavelength region B is the highest visible from 640 nm. The wavelength range is 700 nm. In FIG. 8, there is a more noticeable difference in spectral reflectance at 660 nm or more. However, when a sharp cut filter or the like that transmits light of 660 to 700 nm is used, the amount of light transmitted by the indoor light source is insufficient. No matter how excellent the reflection and absorption characteristics are, the entire image itself will darken and become almost invisible, so a strong light source is often required. From the above, the wavelength region B is set to 640 to 700 nm. Regarding the setting of the wavelength region B, it is only necessary to determine the authentication wavelength desired by the user, select an ink material according to the authentication wavelength, and produce a metameric pair ink, and is not particularly limited to this wavelength region. .

  Next, the halftone dot area ratio of the image 7 having the density gradation formed by the first area 2, the halftone dot area ratio of the latent image 8 formed by the third area 4, and the second area 3. The relationship of the dot area ratio of the camouflaged region 9 of the latent image 8 to be formed will be described.

  The visible image 5 having the density gradation printed by the first region 2, the second region 3, and the third region 4 is printed with a halftone dot area ratio in the first predetermined range, and the first region 2 is printed. The image 7 having the density gradation printed by is printed with the halftone dot area ratio in the second predetermined range, and the camouflage area 9 printed by the second region 3 is the halftone dot area in the third predetermined range. The latent image 8 printed at the rate and printed by the third region 4 needs to be printed at the dot area rate in the fourth predetermined range.

  The visible image 5 having the density gradation composed of the first region 2, the second region 3, and the third region 4 printed with the first printing ink and the second printing ink has a halftone dot area within a predetermined range. The latent image 8 composed of the third region 4 printed at a rate and printed with the second printing ink needs to be printed below the minimum halftone dot area rate of the visible image 5 having a density gradation.

The halftone dot area ratio of the first predetermined range of the visible image 5 having the density gradation printed by the first region 2, the second region 3, and the third region 4 is printed at 40 to 80% or less, The halftone dot area ratio of the second predetermined range of the image 7 having the density gradation printed by the first region 2 is printed at 0 to 40 % or less, and the camouflage region 9 printed by the second region 3 is printed. The halftone dot area ratio of the third predetermined range is printed at 40% or less, and the halftone dot area ratio of the fourth predetermined range of the latent image 8 printed by the third region 4 is printed at 40% or less. It is preferable.

  Next, a visible image 5 having a density gradation composed of a first region 2, a second region 3, and a third region 4 printed with the first printing ink and the second printing ink, FIG. 9 shows the relationship between the camouflaged area 9 composed of the second area 3 printed with the printing ink and the density gradation area of the latent image 8 composed of the third area 4 printed with the second printing ink. I will explain.

  As a means for concealing the latent image, the halftone dots of the third region 4 printed with the second printing ink that forms the latent image 8 and the camouflage region 9 that forms a pair with the halftone dots are formed. The sum of the halftone dot area ratios combining the halftone dots of the second region 3 printed with one printing ink is set to a constant value.

  In the wavelength region A, the region printed with the first printing ink and the region printed with the second printing ink expressed with a specific reflection density are good in each region in the wavelength region B. A difference can be obtained. A maximum dot area ratio for obtaining a high density difference in the wavelength region B is defined as a dot area ratio A. This is because if the density of the visible image 5 having density gradation is too high, the visible image 5 having density gradation will be visually recognized even in the wavelength region B, so that it is preferable to provide a certain gradation restriction.

  As shown in FIG. 9, in the wavelength region A, the density gradation composed of the first region 2, the second region 3, and the third region 4 printed with the first printing ink and the second printing ink is changed. A density image of a latent image 8 having a visible image 5, a camouflaging region 9 composed of a second region 3 printed with a first printing ink, and a third region 4 printed with a second printing ink. The relationship between the key areas will be described with reference to FIG.

The visible image 5 having the density gradation composed of the first region 2, the second region 3, and the third region 4 printed with the first printing ink and the second printing ink is obtained from the third region 4. A third area printed with the second printing ink and having a halftone dot area ratio (for example, 40%) or more and a halftone dot area ratio A (for example, 80%) or less expressing the latent image 8 The density gradation area of the latent image 8 made up of is composed of the lowest halftone dot area ratio of the visible image 5 having the density gradation, for example, 0 to 40%. The camouflage region 9 composed of the second region 3 printed with the first printing ink is configured with a maximum halftone dot area ratio (for example, 80%) or less, for example, 0 to 40%. The density gradation area of the image 7 having the density gradation composed of the first area 2 printed with the first printing ink has a halftone dot area ratio (for example, 40) obtained by dividing the halftone dot area ratio A by the maximum halftone dot area ratio. %). The halftone dot area ratio of the camouflage area 9 is a constant value (for example, 40%), which is the sum of the halftone dot area ratios combining the halftone dots constituting the latent image 8 and the halftone dots of the camouflage area 9 paired with the halftone dots. ). For example, when the halftone dot area ratio of the latent image 8 is 0, the halftone dot area ratio of the camouflage region 9 to be paired is 40, and when the halftone dot area ratio of the latent image 8 is 20, it becomes a pair. When the halftone dot area ratio of the camouflage area 9 is 20 and the halftone dot area ratio of the latent image 8 is 40, the halftone dot area ratio of the camouflage area 9 to be paired is zero.

  When using the metameric pair ink, the latent image viewed with a filter or the like uses only the light in the wavelength region B out of the light existing in the observation environment. Even in an image that feels like this, in the wavelength region B, the amount of light itself is greatly reduced. Therefore, the reflection and absorption characteristics of the light in the wavelength region B are reflected more strongly, and the density is higher than the density obtained in the wavelength region A. It can be made to feel visually. That is, when the reflection and absorption characteristics of the ink in the wavelength region B are excellent, even if the concentration is only visible as a highlight level in the wavelength region A, the concentration of shadow from the middle when observed through a filter. It is possible to make the observer recognize.

  The printed material B that can be determined as authenticity is a visible image 5 having a density gradation as shown in FIG. 10 (a) under normal light such as sunlight, fluorescent light, or incandescent light having a specific wavelength A, and a latent image. Image 8 cannot be confirmed. The latent image 8 is arranged in the visible image with a fine structure that is invisible to the visible image with a reflection density equal to or lower than that of the visible image 5 having the density gradation. It is completely hidden inside.

  When the printed material B capable of authenticity determination is observed through different light sources in the wavelength region B or through a predetermined filter 10, a latent image 8 is confirmed as shown in FIG. As if the image 7 having the density gradation composed of the first region 2 printed with the first printing ink and the camouflaged region 9 composed of the second region 3 printed with the first printing ink were erased. Thus, it appears that only the latent image 8 is visually recognized. The latent image 8 is composed of the first printing ink in the wavelength region B, although the latent image 8 is composed of a reflection density equal to or lower than the visible image 5 having the density gradation composed of the first region 2 printed with the first printing ink. Since the image 7 having the density gradation to be printed and the camouflage area 9 having the second area 3 are converged to a constant density, the latent image 8 and the first area 2 are By increasing the density difference between the image 7 having the density gradation and the camouflaging area 9 composed of the second area 3, it is possible to develop a latent image having high visibility. The image 7 having the density gradation composed of the first region 2 and the latent image 8 overlap in design, but when observed in the wavelength region B, the latent image 8 has a density composed of the first region 2. The density gradation of the image 7 having gradation is hardly reflected, and the latent image 8, the image 7 having density gradation and the camouflaged area 9 are visually recognized with a clear density difference. It becomes possible to make a false determination.

  Consists of an image 7 having a density gradation composed of a first region 2 printed by the first printing ink used for the printed material B that can be determined as authenticity, and a second region 3 printed by the first printing ink. As an easy procedure for producing the first plate surface 12 of the camouflaged area 9 and the second plate surface 13 of the latent image 8 composed of the third area printed with the second printing ink, FIG. A camouflage region 9 shown in a) and a latent image 8 shown in FIG. 11B are formed, and an image 11 having a constant density shown in FIG. 11C is formed by combining the camouflage region 9 and the latent image 8. Form. In this case, the density is lowered to a level equal to or lower than the lowest halftone dot area ratio of the visible image 5 having density gradation. Next, only the camouflage area 9 is extracted from the latent image 8 and the camouflage area 9 shown in FIG. 11C with respect to the image 7 having the density gradation shown in FIG. Is added to the image 7 having the dot density, and the halftone dot area ratio A is lowered to produce the first printing plate 12 from the image 7 having the density gradation shown in FIG. 11E and the image of the camouflage region 9. For the second printing plate 13, only the latent image 8 is extracted from the latent image 8 and the camouflaged area 9 shown in FIG. However, it goes without saying that the present invention is not limited to this procedure.

  In a printed matter capable of authenticating authenticity, a camouflage pattern is formed on the visible image 5 having a density gradation with at least one color ink (for example, magenta ink and / or yellow ink) having a high spectral reflectance between 640 and 700 nm. By overprinting, a plurality of colors can be provided. Even if it is such a structure, the effect | action mentioned above at the time of observing with a filter etc. is not impaired. This is because when a visible image 5 having a density gradation is overprinted with an ink (for example, magenta ink and / or yellow ink) having a wavelength longer than that of a predetermined filter (for example, SC64 manufactured by FUJI FILM), the filter is applied to the printed matter. This is because the overprinted ink cannot be visually recognized even if it is repeatedly observed. Further, the latent image 8 embedded in the visible image 5 having the density gradation is not visually recognized under normal light.

  The halftone dot shape used in the present invention is not limited to a circular dot, but a random dot or a special halftone dot generation method proposed in Japanese Patent Application Laid-Open No. 11-268228 filed earlier by the present applicant. It is also possible to use a special halftone dot shape having a degree of freedom obtained by converting an input image taking design characteristics into a continuous tone halftone dot composed of a halftone screen.

  The first region 2, the second region 3, and the third region 4 are preferably printed at 60 to 700 line / inch.

  Moreover, the base material used for the printed matter capable of authenticating authenticity of the present invention is not particularly limited, and paper sheets or films such as high-quality paper, coated paper, and art paper can be used.

  The printing method of the printed matter capable of authenticating authenticity of the present invention is not particularly limited, such as an offset printing method, a gravure printing method, a screen printing method, a flexographic printing method, an ink jet printer, or a laser printer. The offset printing method is particularly preferable because it is often required. When actually producing printed matter, in most printing methods, the dot area ratio is expected to increase due to dot gain between the printed matter and the plate surface. It goes without saying that there is a need to do.

  Note that the visible image having the density gradation, the image having the density gradation, and the latent image may be a simple binary image such as a character, a number, or a symbol, or may be a gradation image.

  EXAMPLES Hereinafter, although this invention is demonstrated further in detail using an Example, the content of this invention is not limited to the range of these Examples.

  The printed matter of Example was produced using the 1st printing ink and the 2nd printing ink which have the spectral reflectance curve shown in FIG. The image 7 and the camouflaged area 9 having the density gradation shown in the example were printed with the first printing ink, and the latent image 8 was printed with the second printing ink.

  In carrying out the invention, according to the characteristics of the first printing ink and the second printing ink shown in FIG. 8, first, the dot area ratio A, the camouflaged area 9 and the density of the composite area of the latent image 8 are changed. Made a decision. First, the gradation scales of the first printing ink and the second printing ink to be used were respectively printed, and the reflection density characteristics of both inks in the wavelength region A were confirmed as shown in FIG. In the wavelength region A, it is important that the halftone dot area ratio and the reflection density of the first printing ink and the second printing ink are in a substantially proportional relationship, and as a result of the measurement, it was confirmed that they are in a proportional relationship. Next, in the wavelength region B, the density difference between the first printing ink and the second printing ink was determined by visual inspection through a sharp cut filter. It is also possible to calculate the integral value in the wavelength region B of the spectral spectrum based on the dot area ratio of each of the first printing ink and the second printing ink.

It was confirmed that the latent image 8 has a sufficient gradation in the wavelength region B when it is printed with the second printing ink in a range where the halftone dot area ratio is 0 to 40% or less. The camouflage area 9 printed with the first printing ink is formed with a halftone dot area ratio of 0 to 40% or less, and the halftone dots constituting the latent image 8 and the camouflage area 9 paired with the halftone dots are formed. The sum of the halftone dot area ratios combining the halftone dots was set to a constant value (40%). Since the halftone dot area ratio printed with the first printing ink was confirmed to be in a range where 80% or less of continuous gradations are within a certain gradation in the wavelength region B, a visible image having density gradations. No. 5 was formed with a dot area ratio of 80% or less. Therefore, the visible image 5 having the density gradation printed with the first printing ink and the second ink was formed with a halftone dot area ratio of 40 to 80% or less.

  The latent image 8 and the image 7 having density gradation preferably have a gradation representation area of 25% or more due to a difference in the dot area ratio.

  Using the first printing ink and the second printing ink, a printed material C that can be determined by an offset proofing printing machine was prepared.

  As shown in FIG. 13, the printed material C capable of authenticating authenticity includes a plurality of first regions 2 and second regions 3 that are alternately adjacent to each other on the substrate 1, and a third region 3 in the second region 3. The region 4 is arranged by hair removal to form a visible image 5 having a density gradation. The dot area ratio of the visible image 5 having the density gradation is formed in the range of 40 to 80% or less. An image 7 having a density gradation is formed by the first region 2, a latent image 8 is formed by the third region 4, and a camouflaged region 9 is formed by the second region 3. The halftone dot area ratio of the latent image 8 is formed in a range of 0 to 40% or less, and the halftone dot area ratio of the camouflage area 9 is formed in a range of 0 to 40% or less. The halftone dot area ratio of the composite region of 8 was adjusted to be 40%.

  As shown in FIG. 14 (a), only the visible image 5 having a density gradation is confirmed in the printed material C that can be determined as authenticity under normal light from sunlight, a fluorescent light, an incandescent light bulb, or the like having a specific wavelength A. . The latent image 8 could not be confirmed.

  As shown in FIG. 14B, the printed material C capable of authenticating authenticity has a density gradation when observed with light in the wavelength region B (640 nm to 700 nm) through the sharp cut filter 10 (SC64 manufactured by FUJI FILM). A latent image 8 was confirmed.

It is a figure which shows the conventional metameric pair printed matter. It is a figure which shows the problem of the conventional metameric pair printed matter. This is a printed matter B of the present invention capable of authenticating authenticity. It is a figure which shows the positional relationship of tweezers. FIG. 3 is a diagram illustrating a boundary between a second region 3 and a third region 4. FIG. 4 is a diagram illustrating a relationship between a first region 2, a second region 3, and a third region 4. It is explanatory drawing of the printed matter B which can authenticate authenticity of this invention. It is a figure which shows an example of the spectral reflectance curve of the 1st printing ink which is a metameric pair ink used by this invention, and a 2nd printing ink. A visible image 5 having a density gradation composed of a first region 2, a second region 3, and a third region 4 printed with the first printing ink and the second printing ink, and the first printing ink. It is explanatory drawing about the relationship between the camouflage area | region 9 which consists of the 2nd area | region 3 printed, and the density gradation area | region of the latent image 8 which consists of the 3rd area | region printed with 2nd printing ink. It is explanatory drawing about the effect | action of the printed matter B which can authenticate authenticity of this invention. It is explanatory drawing which shows the method for producing the 1st printing plate and the 2nd printing plate. It is a figure which prints the gradation scale of 1st printing ink and 2nd printing ink, respectively, and shows the reflection density characteristic in the wavelength range A. FIG. It is explanatory drawing of the printed matter C which can authenticate authenticity of an Example. It is a figure which shows the effect | action of the printed matter C which can authenticate authenticity of an Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Base material 2 1st area | region 3 2nd area | region 3a Non-printing area | region 4 3rd area | region 5 Visible image 6 which has density gradation Overlapping area 7 Image having density gradation 8 Latent image 9 Camouflage area 10 Filter 11 Image with constant density 12 First printing surface 13 Second printing surface A Printed material B, C Printed material with authenticity discrimination

Claims (3)

A plurality of first areas and second areas are alternately arranged adjacent to each other on the base material, and a third area is arranged by hair removal in the second area to form a visible image having a density gradation. An image having a density gradation is formed by the first region, a latent image is formed by the third region, the second region becomes a camouflage region of the latent image, and the first region The area and the second area are printed with the first printing ink, the third area is printed with the second printing ink, and the spectral reflectance of the first printing ink and the second printing ink is visible. The first wavelength range in the region is approximated and the second wavelength range in the visible region is printed with different values of the metameric pair ink;
The halftone dot area ratio of the image having the density gradation is formed with 0 to 80% or less, the halftone dot area ratio of the latent image is formed with 40% or less, and the halftone dot area ratio of the camouflage region is , And the halftone dot area ratio is a sum of the halftone dot area ratios in which the halftone dots constituting the latent image and the halftone dots of the camouflage area paired with the halftone dots are combined. And a visible image having the density gradation formed by the first region, the second region, and the third region in the second region is a halftone dot area. A printed matter capable of authenticating authenticity, characterized by being configured with a rate of 80% or less. The integral value of the spectral reflection spectrum between 640 and 700 nm of the first printing ink has at least twice the integral value of the spectral reflection spectrum between 640 and 700 nm of the second printing ink. 2. The true value of the spectral reflection spectrum of the printing ink between 400 and 600 nm is substantially the same as the integral value of the spectral reflection spectrum of the second printing ink between 400 and 600 nm. Prints that can be falsely identified 3. The printed matter capable of authenticating authenticity according to claim 1, wherein the latent image has a density gradation.

Images