JP7459588B2 - Information recording body and printed matter comprising information recording body - Google Patents

Description

The present invention relates to an information recording medium that is difficult to prevent counterfeiting and a printed matter that includes the same.

2. Description of the Related Art Conventionally, electronic watermarking technology has been used to embed information in printed matter at a level that humans cannot visually recognize, and to read the embedded information with a reading device without damaging the aesthetic appearance of the printed matter.

As a printed matter using digital watermark technology, Patent Document 1 below describes an information record that includes a composite image including an image printed on a glitter layer and an image formed on the image and printed as a transparent layer. Both images are printed with ink that has a different amount of reflected light depending on the viewing angle, and one of the composite images can be recognized depending on the viewing angle, and the image printed on the glitter layer is printed in the spatial frequency domain. An image is disclosed in which feature points in the spatial frequency domain have regularity, and an image printed on a transparent layer is an image in which the feature points in the spatial frequency domain are arranged at positions that interfere with the regularity.

Japanese Patent Application Publication No. 2016-93895

In this case, the image printed on the photoluminescent layer is a code pattern that cannot be visually recognized by humans, so there is a demand for anti-counterfeiting technology with a high level of design. Another example of an anti-counterfeiting medium that takes design into consideration is a hologram. Since holograms are usually formed with a fixed design, when adding individual information for anti-counterfeiting purposes, it is necessary to print, for example, a two-dimensional barcode with a printer on the outside of the design formation part of the hologram label. However, such codes are easily copied, and there is a problem in that they are not sufficiently effective at preventing counterfeiting.

The present disclosure has been made in view of the above situation, and an object of the present disclosure is to provide an information recording body in which embedded information is difficult to copy without impairing the design, and a printed matter including the information recording body.

The information recording body according to the present embodiment is an information recording body having a composite image including a first image formed on a hologram layer and a second image formed on the first image, The two images are printed with ink that has a different amount of reflected light depending on the viewing angle, and in the composite image, one image can be recognized by a reading device depending on the viewing angle, and the second image is meaningless to a person at first glance. This is an image that has regularity in feature points in the spatial frequency domain.

An information recording body according to another embodiment of the present invention is an information recording body including a composite image including a first image formed on a hologram layer and a second image formed on the first image, The second image is printed with ink that has a different amount of reflected light depending on the viewing angle, and in the composite image, one image can be recognized by a reading device depending on the viewing angle, and the one image is different from what a person sees at first glance. The second image is an image that has regularity in feature points in the spatial frequency domain, and a part of the first image includes at least one of the feature points in the spatial frequency domain. The image is an image in which one or more of the feature points are arranged at a position that obstructs the regularity.

Further, in the information recording body according to another embodiment of the present invention, the first image is visible at a first position where the observation angle is different from an output angle at the time of specular reflection with respect to an incident angle of the illumination light source, and , the first image is invisible at a second position where the second image is invisible and the observation angle is the same as the exit angle during specular reflection with respect to the incident angle of the illumination light source, and , the second image is visible and is located between the first position and the second position; the observation angle is different from the output angle at the time of specular reflection with respect to the incident angle of the illumination light source; At a third position near the second position, both the first image and the second image may be visible.

Further, in the information recording body according to another embodiment of the present invention, the first shape is represented by feature points in a spatial frequency domain of a part of the first image, and the first shape is expressed by feature points in the spatial frequency domain of the second image. The second shape may be the same shape or a similar shape.

In addition, in an information recording medium according to another embodiment of the present invention, the first shape and the second shape may be repeated shapes.

Moreover, in the information recording medium according to another embodiment of the present invention, the part of the first image and the second image may be images in which feature points in a spatial frequency domain appear at specific positions.

In addition, in an information recording medium according to another embodiment of the present invention, the second image may be formed of a transparent material to form a transparent layer, a transparent substrate may be disposed between the hologram layer and the transparent layer, and the refractive index of the transparent layer may differ from the refractive index of the substrate by 0.1 or more.

In the information recording body according to another embodiment of the present invention, the second image is formed of a transparent material to constitute a transparent layer, and a transparent layer is provided on a side of the transparent layer opposite to the hologram layer. A base material may be arranged, and the refractive index of the transparent layer may have a difference of 0.1 or more from the refractive index of the base material.

In addition, in the information recording medium according to another embodiment of the present invention, a release layer may be further disposed between the transparent layer and the substrate, and the refractive index of the transparent layer may differ from the refractive index of the release layer by 0.1 or more.

In addition, in an information recording medium according to another embodiment of the present invention, the second image may be composed of ink made of the transparent material that is excited by infrared or ultraviolet light and emits visible light.

Moreover, in the information recording medium according to another embodiment of the present invention, the second image may be formed of ink containing an infrared absorbing material.

Moreover, in the information recording medium according to another embodiment of the present invention, the second image may be formed of ink containing a polarizing material.

Further, the printed matter according to this embodiment includes the above-mentioned information recording body.

According to the present embodiment, it is possible to provide an information recording body in which embedded information is difficult to copy without impairing the design.

FIG. 2 is a cross-sectional view for explaining a layer structure of the information recording medium according to the first embodiment. 1A and 1B are diagrams illustrating a printed matter including an information recording medium according to a first embodiment and a layer structure of the printed matter. FIG. 3 is a diagram for explaining an observation mode based on the structure of the information recording body according to the first embodiment. FIG. 7 is a diagram for explaining an observation mode based on the structure of an information recording body according to a second embodiment. It is a figure which shows the example of the pattern image of the information recording body based on 1st and 2nd embodiment. FIG. 6 is a diagram for explaining a spatial frequency domain when the pattern images according to the first and second embodiments are subjected to frequency conversion. FIG. 6 is a diagram for explaining a spatial frequency domain when the pattern images according to the first and second embodiments are subjected to frequency conversion. 10A and 10B are diagrams for explaining a spatial frequency domain when a pattern image according to the first and second embodiments is frequency-converted; FIG. 6 is a diagram for explaining a spatial frequency domain when the pattern images according to the first and second embodiments are subjected to frequency conversion. FIG. 2 is a functional block diagram of a reading device according to first and second embodiments. 5 is a flowchart showing a code identification process in the reading device according to the first and second embodiments. 4 is a diagram for explaining the positional relationship between an illumination light source and a camera when copying the information recording medium according to the first and second embodiments. FIG. FIG. 3 is a diagram for explaining the positional relationship between an illumination light source and a camera when copying printed matter according to the first and second embodiments. 1A and 1B are diagrams for explaining copies of the information recording medium and the printed matter according to the first and second embodiments. 11 is a cross-sectional view for explaining a layer structure of an information recording medium according to Modification 1 and Modification 2. FIG.

Below, an example of the information recording medium of the present disclosure will be described with reference to the drawings, etc. However, the information recording medium of the present disclosure is not limited to the embodiment and examples described below.

Note that each figure shown below is shown schematically. Therefore, the size and shape of each part are appropriately exaggerated to facilitate understanding. Further, in each figure, hatching indicating a cross section of a member is omitted as appropriate. Numerical values such as dimensions and material names of each member described in this specification are examples of embodiments, and are not limited to these, and can be appropriately selected and used. In this specification, terms specifying shapes and geometrical conditions, such as terms such as parallel, perpendicular, and perpendicular, are not only meant strictly, but also include substantially the same state.

1. First embodiment A first embodiment of the information recording body of the present disclosure will be described. FIG. 1 is a cross-sectional view illustrating an information recording body 30 according to the first embodiment, and FIG. 2(a) is a plan view illustrating a printed matter 10 including an information display body 30 according to the first embodiment. Also, FIG. 2(b) is a cross-sectional view for explaining the layer structure of the printed matter 10 of FIG. 2(a). The cross-sectional view is a view of a cross section cut at a cross section perpendicular to the short side direction, passing through line A-A along the long side direction, at approximately the center of the information recording body 30 along the short side direction of the printed matter 10 of FIG. 2(a), as viewed from the lower side of the paper. Also, FIG. 3 is a view for explaining an observation mode based on the structure of the information recording body 30 according to the first embodiment.

(a) Information recording body As shown in the cross-sectional view of FIG. 1, the information recording body 30 has an adhesive layer 34, a hologram layer 31, a base material 33, and a transparent layer 32 laminated in this order from one side. . Note that the adhesive layer 34 is provided as necessary so that the information recording body 30 can be attached to another medium, and is not an essential element of the information recording body 30. The adhesive layer 34 may not be provided, or may be made of some kind of base material or resin that supports the hologram layer 31. The hologram layer 31 is, for example, a relief hologram, but may also be a volume hologram. The hologram layer 31 is formed with a design that takes aesthetics into consideration, and is designed so that the design can be clearly recognized only when the paper 11 is viewed from a predetermined viewing direction.

The information recording medium 30 can be used as an anti-counterfeiting medium by itself, or can be attached to or incorporated into other media, products, etc. as necessary to prevent the media, products, etc. from being counterfeited. In one example of this embodiment, it is used to form part of a printed matter 10, such as a ticket or admission ticket for a movie, concert, amusement park, etc., as shown in Figure 1.

(b) Hologram Layer The hologram layer 31, which is a relief hologram, is composed of a reflective layer 31b adjacent to the adhesive layer 34 and a resin layer 31a adjacent thereto. On the other hand, a transparent layer 32 is formed on the outermost surface of the information recording body 30 on the side opposite to the paper 11 with a base material 33 interposed therebetween. The transparent layer 32 is printed with ink of a transparent material whose amount of reflected light differs depending on the viewing angle, and constitutes a pattern image formed independently of the design of the hologram layer 31. However, the transparent layer 32 may constitute a pattern image related to the design of the hologram layer 31. In the plan view of the paper 11, the pattern image of the transparent layer 32 is at least partially different from the pattern image (first image) formed on the hologram layer 31 and the pattern image (second image) formed on the transparent layer 32. are arranged so that they overlap.

However, the range of directions in which the pattern image formed on the hologram layer 31 can be observed is offset from the range of directions in which the pattern image formed on the transparent layer 32 can be observed. Therefore, when the observation direction of the paper 11 is changed, there are positions where only the pattern image (first image) formed on the hologram layer 31 can be observed, positions where a composite image of the pattern images formed on the hologram layer 31 and the transparent layer 32 can be observed, and positions where only the pattern image (second image) formed on the transparent layer 32 can be observed. Therefore, by setting an observation direction in which only the pattern image formed on the transparent layer 32 can be observed, it is possible to perform visual observation and good reading of the embedded information by a reading device. The configuration of the hologram layer 31 will be described below.

(i) Resin layer The resin layer 31a may be, for example, a cured resin layer obtained by curing a transparent thermosetting resin, an ionizing radiation curable resin, or the like, a thermoplastic resin layer, a silver salt material, a dichromated gelatin emulsion, a thermoplastic, a diazo-based photosensitive material, a photoresist, a ferroelectric, a photochromic material, a thermochromic material, a photosensitive layer made of a photosensitive material such as chalcogen glass, or the like. Details of the thermosetting resin and ionizing radiation curable resin, which are the materials of the cured resin layer, as well as the thermoplastic resin, may be the same as those of the resin material of the hologram layer described in, for example, JP-A-2014-126799. In addition to the above-mentioned materials, the relief hologram may contain any material that can generally be added to a relief hologram.

The shape etc. of the relief structure of the resin layer 31a may be any shape as long as it can express a desired hologram reproduction image, and can be appropriately determined in the same manner as the relief structure of a general relief type hologram. Any material having an uneven structure corresponding to interference fringes, that is, a relief structure on its surface may be used, and any known material may be used.

(ii) Reflective layer A reflective layer 31b is provided on the surface of the resin layer 31a on which the relief structure is formed. This is because the reflective layer 31b has a unique optical design due to the action and effect of the relief structure of the resin layer 31a and the reflective layer 31b. In addition, the presence of the reflective layer 31b can increase the reflection and diffraction efficiency of the relief structure, and can produce a high-brightness hologram reproduction image. It is preferable that the reflective layer 31b is opaque. In addition, for the specific configuration of the reflective layer 31b, for example, a metal reflective layer described in JP-A-2013-014081, JP-A-2014-092646, etc. can be used. In addition, the reflective layer may have adhesiveness or thermal adhesiveness.

(c) Adhesive Layer The adhesive layer 34 is provided to firmly adhere the information recording medium 30 to the surface of the paper 11, and preferably has a strength such that when the information recording medium 30 is to be peeled off in order to replace it with a counterfeit, at least the hologram layer 31 and the transparent layer 32 described later are broken first. This is because it makes counterfeiting the information recording medium 30 even more difficult. However, unless there is a purpose to attach the information recording medium 30 to other media or products, such as forming it on the paper 11 of the printed matter 10, the adhesive layer 34 is not necessary for the information recording medium 30. In addition, in order to provide the information recording medium 30 with a certain strength, the adhesive layer 34 may be replaced with other resin materials that do not have adhesive properties.

The adhesive layer 34 may be made of a known heat-sensitive adhesive that melts or softens when heated to exert its adhesive effect. Materials that can be used include polyester resin, vinyl chloride-vinyl acetate copolymer resin, acetal resin, butyral resin, cellulose resin, acrylic resin, urethane resin, amide resin, epoxy resin, rubber-based resin, ionomer resin, etc. If necessary, various additives are added and dissolved or dispersed in an organic solvent to prepare an ink that is an adhesive layer composition, which is then applied and dried by a known coating or printing method to form the adhesive layer. The thickness of the adhesive layer 34 may be, for example, 0.1 μm or more and 50 μm or less, but is preferably 0.5 μm or more and 1.5 μm or less.

(d) Base material The base material 33 supports the transparent layer 32 formed on the outermost surface of the information recording body 30 on the side opposite to the paper 11 side, and is arranged on the side opposite to the transparent layer 32 side. It has a function of protecting the hologram layer 31. As the base material 33, film base materials may be laminated, or resin may be laminated. When the base material 33 is used as a film base material, for example, polyester films such as polyethylene terephthalate films, polyethylene films, polypropylene films, polyfluoroethylene films, polyvinylidene fluoride films, and polychloride films are used, although there are no particular limitations. Vinyl film, polyvinylidene chloride film, ethylene-vinyl alcohol film, polyvinyl alcohol film, polymethyl methacrylate film, polyether sulfone film, polyether ether ketone film, polyamide film, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer film, polyimide Examples include films.

When the base material 33 is a resin, examples of the resin include acrylic and methacrylic resins such as polymethyl acrylate and polymethyl methacrylate, polyvinyl chloride resin, cellulose resin, silicone resin, chlorinated rubber, casein, various surfactants, metal oxides, etc., or a mixture of two or more of these, epoxy modified acrylate resin, urethane modified acrylate resin, acrylic modified polyester, etc.

The thickness of the base material 33 only needs to have transparency to the extent that it does not impede the visibility of the hologram reproduced image, and can be, for example, 0.1 μm or more and 100 μm or less, and 0.5 μm or more and 50 μm or less. The following is preferable. The light transmittance of the base material 33 does not need to be defined by a strict numerical value, and can be appropriately determined within a range that does not impede the function of the information recording body 30 of this embodiment. Note that in the present disclosure, transparent includes colorless and transparent and colored and transparent to the extent that visibility is not hindered. Moreover, it is preferable that the haze value of the base material 33 is low. This is because if the haze value of the protective layer is high, the display of the hologram reproduced image may be inhibited, and the hiding effect of the image formed on the transparent layer 32, which will be described later, may be impaired. The specific haze value of the base material 33 is preferably approximately 0.5 or more and 15 or less.

(e) Transparent Layer The transparent layer 32 is a layer in which a pattern image (second image) different from the pattern image of the hologram layer 31 is printed using ink of a transparent material. The transparent layer 32 is formed on a base material 33 laminated on the surface of the hologram layer 31 opposite to the paper 11 . The transparent layer 32 is a layer in which a pattern image is formed on the base material 33 using ink of a transparent material, for example, by gravure printing. Examples of such transparent material inks include matte OP varnish, transparent varnish, ink varnish, and medium ink. Note that these inks may be any printing ink such as ultraviolet curing ink, oxidation polymerization ink, penetrating ink, superheat drying ink, evaporation drying ink, etc.

In order to make the pattern image made of the transparent ink forming the transparent layer 32 easier to see or easier to read with a reading device, it is preferable that the refractive index of the transparent layer 32 has a difference of 0.1 or more and 0.4 or less with respect to the refractive index of the substrate 33 supporting it. In particular, in this embodiment, it is preferable that the refractive index of the transparent layer 32 is smaller than the refractive index of the substrate 33 supporting it, in the range of 0.1 or more and 0.4 or less. In this case, light incident from the outside toward the transparent layer 32 is more likely to be totally reflected at the boundary surface between the transparent layer 32 and the substrate 33 below it, and the reflected light from the transparent layer 32 increases, making it easier to see the pattern image made of the transparent ink or easier to read with a reading device. This condition can also be applied to other embodiments and modified examples described later.

(f) Printed matter As described above, the printed matter 10 illustrated in FIG. 2(a) is, for example, a ticket, admission ticket, card, etc. for a movie, a concert, an amusement park, etc. The printed matter 10 itself has monetary value, but a copy of the printed matter 10, such as a color copy, naturally has no monetary value. The printed matter 10 includes a paper 11 and an information recording body 30. Here, the paper 11 is a base material for the printed matter 10, and is typically a white paper, but the paper may be high-quality paper or coated paper, or may be a plastic other than paper. Alternatively, it may be a mixed material or a laminated material of paper and plastic. In any case, the paper 11 may be any paper as long as it can support an information recording body 30, which will be described later, or bear various printed patterns indicating ticket types and the like.

The printed matter 10 including the information recording body 30 has a layer structure as shown in the cross-sectional view of FIG. 2(b). That is, the information recording body 30 is formed on one surface of the paper 11 of the printed matter 10, and an adhesive layer 34, a hologram layer 31, a base material 33, and a transparent layer 32 are laminated in this order from the side closest to the surface of the paper 11. The hologram layer 31 is exemplified by a relief type hologram, but may also be a volume type hologram. The hologram layer 31 is formed with a design that takes into consideration the design, and is designed so that the design can be clearly seen only when the paper 11 is viewed from a specified observation direction.

(g) Manufacturing method of information recording body and printed matter including the same Next, a manufacturing method of the above-mentioned information recording body 30 and printed matter 10 including the same will be briefly described. First, the information recording body 30 can be obtained by forming a transparent layer 32 by overlaying a predetermined pattern image with a transparent ink or the like on the surface of one side of a support base material such as PET that supports the information recording body 30, by gravure printing, etc., and then forming a hologram layer 31, as in the modified example 2 described later. Note that if a peeling layer is provided between the support base material and the transparent layer 32 and an adhesive layer 34 is provided on the surface of the hologram layer 31 opposite to the transparent layer 32, the part excluding the support base material and the peeling layer can be thermally transferred onto the surface of another medium such as paper 11. In addition, the printed matter 10 is obtained by preparing a paper 11 on which the contents of a ticket or the like are printed in advance, and transferring a laminate of the adhesive layer 34, the hologram layer 31, and the base material 33, which have been formed in a separate process, to a partial area on one side of the paper 11 by thermal transfer or the like. Thereafter, a predetermined pattern image is printed on the surface of the base material 33, which is the outermost surface of the laminate, by gravure printing or the like using transparent ink or the like to form a transparent layer 32, thereby completing the laminate. Alternatively, the transparent layer 32 may be formed on the laminate in advance, and then the laminate may be thermally transferred to the paper 11.

(h) Effect of information recording body First, in a printing area of a certain area printed in the printing process of the transparent layer 32 of the information recording body 30, the printing condition expressed in % as the area that can hide the base is defined as the area ratio, In particular, the printing of the transparent layer 32 will be described using the dot area ratio as the case where the underlying layer can be hidden by the dots. In FIG. 3(a), a pattern image 31p consisting of a design having design properties is formed on the hologram layer 31, and a pattern image 31p consisting of a design having design properties is formed on the transparent layer 32, and an image that does not have design properties and is meaningless to a person at first glance. It is a figure which shows the state where the pattern image 32p of a certain two-dimensional code is printed.

The transparent layer 32 has a foreground portion 32a and a background portion 32b. The foreground portion 32a is the pattern image 32p itself, and is printed with a dot area ratio of 100%. The background portion 32b is printed with a dot area ratio of 25%. However, this ratio is merely an example and is not limiting. For example, the dot area ratio of the foreground portion 32a may be less than 100%, and the dot area ratio of the background portion 32b may be greater than or less than 25% as long as there is a predetermined difference between the foreground portion 32a and the background portion 32b. The density of the foreground portion 32a and the background portion 32b may also be reversed.

In addition, the transparent layer 32 may be a pattern image consisting only of the foreground part, and in that case, the printing area of image C2, which will be described later, is printed with a halftone dot area ratio of 100%, and the printing area and the non-printing area that is not printed are printed. The pattern image can be expressed in binary values depending on the region.

The printing process for forming the transparent layer 32 is not limited to gravure printing, and may be wet offset printing, dry offset printing, letterpress printing, waterless planography, flexo printing, screen printing, intaglio printing, or the like. The recognizable image of the information recording body 30 printed in the above-described printing process changes depending on the viewing angle (observation angle).

Figure 3(b) illustrates three positional relationships between the illumination light source 21, the viewpoint 22, and the information recording medium 30 when the viewpoint 22 is at position P1, which is the reconstructed image viewing angle region of the hologram layer 31 and a non-specular reflection (mirror reflection) region of the transparent layer 32 (excluding the region near specular reflection), position P2, which is the reconstructed image viewing angle region of the hologram layer 31 and a region near specular reflection of the transparent layer 32, and position P3, which is the non-reconstructed image viewing angle region of the hologram layer 31 and a specular reflection region of the transparent layer 32. For example, the incident angle of the illumination light source 21 is α, and the observation angles of positions P1, P2, and P3 of the viewpoints 22a, 22b, and 22c are β1, β2, and β3, respectively.

When the viewpoint 22 (22a or 22b) is located at position P1 or P2 with respect to the positions of the illumination light source 21 and the information recording body 30, it means that the observation is made in the viewing angle area of the reproduced image of the hologram layer 31, and the viewing angle is at position P3. When there is a viewpoint 22 (22c), the observation is made in the specular reflection area of the transparent layer 32. Here, α=β3, and the position P3 is a position where the component of the incident light that entered the information recording body 30 from the illumination light source 21 and specularly reflected on the surface of the information recording body 30 can be observed. Further, β1 and β2 are predetermined angles different from α, and positions P1 and P2 are predetermined angles at which the incident light that has entered the information recording body 30 from the illumination light source 21 is reflected on the surface of the information recording body 30. This is the position where the reflected components can be observed. However, when the viewpoint 22 (22a) is located at the position P1, it means that the observation is made in the non-specular reflection area (excluding the region near the specular reflection) of the transparent layer 32, and when the viewpoint 22 (22b) is located at the position P2, the hologram is observed. This means that the observation was made in the non-reconstructed image viewing angle region of the layer 31. This can be achieved by designing the uneven shape and the uneven pitch of the hologram layer 31 so that the light incident at the incident angle α is reflected only in a predetermined angle range including the exit angles β1 and β2.

Theoretically, the pattern image 32p of the transparent layer 32 can be clearly seen only in the specular reflection area of the transparent layer 32, and the pattern image 32p cannot be seen at all in areas outside the specular reflection area. It is considered that this is not possible. However, in reality, due to variations in the formation of ink on the transparent material, surface irregularities of the transparent layer 32, undulations of the paper 11, etc., even areas slightly outside the specular reflection area where the incident angle and exit angle are the same It is possible to visually recognize the pattern image 32p. However, the visibility level of the pattern image 32p in this case is inferior to the visibility level of the specular reflection area. Such a region having a viewpoint angle (observation angle) that is not good but allows the pattern image 32p to be visually recognized is defined as a region near regular reflection. The region near regular reflection can generally be an angle obtained by adding or subtracting about 0° to 5° from the angle of regular reflection.

In FIG. 3(c), when the information recording body 30 consists of only the hologram layer 31, the amount of reflected light of the pattern image 31p is smaller than that of the other areas at the position P1 or P2 which is the reproduced image viewing angle area. The pattern image 31p becomes larger, and the pattern image 31p can be clearly recognized. In other words, the pattern image 31p is clearly visible (state #1). However, since the design is such that the amount of reflected light from the pattern image 31p is maximized at position P1, the amount of reflected light from the pattern image 31p at position P2 is smaller than that at position P1, and visibility is slightly reduced accordingly. (state #2). Furthermore, at position P3, which is a non-reproduced image viewing angle region, the pattern image 31p is no longer visible because it is designed so that there is no (or almost no) amount of reflected light from the pattern image 31p (state #3).

Next, when the information recording medium 30 is made of only the transparent layer 32, at position P1, which is a non-specular reflection area excluding the specular reflection area and the specular reflection vicinity area, the foreground portion 32a and the background portion 32b cannot be distinguished because they are transparent (state #4). At position P3, which is a specular reflection area, the amount of reflected light varies greatly depending on the density difference between the foreground portion 32a and the background portion 32b, so the foreground portion 32a and the background portion 32b can be clearly distinguished. In other words, the pattern image 32p is clearly visible (state #6). At position P2, which is a specular reflection vicinity area, the difference in the amount of reflected light due to the density difference between the foreground portion 32a and the background portion 32b is smaller than in the specular reflection area, but the foreground portion 32a and the background portion 32b can be barely distinguished. In other words, the pattern image 32p is visible (state #5).

When the information recording body 30 is one in which the transparent layer 32 is formed on the hologram layer 31 via the base material 33, at the position P1 which is the reproduced image viewing angle region and the non-specular reflection region. Since the pattern image 31p is visible and the foreground portion 32a and the background portion 32b cannot be distinguished, only the pattern image 31p is observed as a whole (state #7). Furthermore, at position P2, which is the reproduced image viewing angle region and the region near specular reflection, the pattern image 31p is visible and the foreground portion 32a and the background portion 32b can be distinguished, and the pattern image 31p and the pattern image as a whole are visible. A 32p composite image is observed (state #8). Here, the pattern image 31p is an image that can be visually recognized as a meaningful image by people, but it is formed so as to overlap at least a part of the pattern image 32p so as to obstruct the visibility of the pattern image 32p. There is. Furthermore, at position P3, which is a non-reconstructed image viewing angle region and a specular reflection region, the pattern image 31p is not visible, the foreground portion 32a and the background portion 32b can be distinguished, and the pattern image 32p is observed as a whole. (state #9).

In this way, by using ink for the transparent layer 32 that reflects different amounts of light depending on the observation angle, the image on the hologram layer 31 and the image on the transparent layer 32 can be displayed in a variety of ways, with the image appearing or not appearing depending on the observation angle. The method of implementing this embodiment will be described later in the explanation of the second embodiment.

2. Second embodiment (a) Configuration of information recording body of second embodiment Next, a second embodiment of the information recording body of the present disclosure will be described. The information recording body 30a according to the second embodiment has the same configuration as the information recording body 30 according to the first embodiment shown in FIG. 2. Also, FIG. 4 is a diagram for explaining the observation mode based on the structure of the information recording body 30a according to the second embodiment. The information recording body 30a according to the second embodiment is different from the first embodiment in that, as shown in FIG. 4(a), in addition to the pattern image 31r composed of a design having design, a two-dimensional code pattern image 31q, which is an image that does not have design and is meaningless at first glance, is provided adjacent to the hologram layer 31. The configuration of the transparent layer 32 and the other configurations of the information recording body 30a are the same as the configuration of the information recording body 30 according to the first embodiment.

In FIG. 4(a), for ease of explanation, the pattern formed on the hologram layer 31 is illustrated as a parallel arrangement of a pattern image 31r consisting of a design and a pattern image 31q of a two-dimensional code. However, the present invention is not limited to this configuration. For example, the pattern image 31r consisting of a design can be arranged approximately in the center, and the pattern image 31q of the two-dimensional code can be arranged outside the pattern image 31r as a background. In this way, the pattern image 31q of the two-dimensional code can be integrated with the pattern image 31r to form a design pattern with a single design. Furthermore, by forming the pattern image 31q of the two-dimensional code as a regular lattice pattern, the design can be further improved as a background image.

Figure 3(b) illustrates three positional relationships between the illumination light source 21, the viewpoint 22, and the information recording medium 30 when the viewpoint 22 is at position P1, which is the reconstructed image viewing angle region of the hologram layer 31 and, as in the first embodiment, is a non-specular reflection (mirror reflection) region of the transparent layer 32 (excluding the region near specular reflection), position P2, which is the reconstructed image viewing angle region of the hologram layer 31 and is a region near specular reflection of the transparent layer 32, and position P3, which is the non-reconstructed image viewing angle region of the hologram layer 31 and is a specular reflection region of the transparent layer 32.

In FIG. 4(b), when the information recording body 30 consists of only the hologram layer 31, at position P1 or P2 which is the reproduced image viewing angle region, the amount of reflected light from the pattern images 31q and 31r is different from that in other regions. The pattern images 31q and 31r are clearly visible. In other words, pattern images 31q and 31r are clearly visible (state #11). However, since the design is such that the amount of reflected light from the pattern images 31q and 31r is maximized at position P1, the amount of reflected light from pattern images 31q and 31r at position P2 is smaller than that at position P1, and the visual recognition is accordingly reduced. performance is slightly decreased (state #12). In addition, at position P3, which is a non-reproduced image viewing angle region, the pattern images 31q and 31r are designed so that there is no (or almost no) amount of reflected light, so the pattern images 31q and 31r are no longer visible (state # 13).

Next, when the information recording medium 30 is made of only the transparent layer 32, it is the same as the pattern image 32p of the first embodiment, and it is in states #14, #15, and #16 corresponding to states #4, #5, and #6. And when the information recording medium 30 is a hologram layer 31 on which the transparent layer 32 is formed via the substrate 33, at position P1, which is the reconstructed image viewing angle region and the non-regular reflection region, the pattern images 31q and 31r are visible, and the foreground portion 32a and the background portion 32b cannot be distinguished, so that only the pattern images 31q and 31r are observed as a whole (state #17). At position P2, which is the reconstructed image viewing angle region and the regular reflection vicinity region, the pattern images 31q and 31r are visible, and the foreground portion 32a and the background portion 32b can be distinguished, so that a composite image of the pattern images 31q, 31r, and the pattern image 32p is observed as a whole (state #18). Here, pattern image 31q is a meaningless image at first glance, and is formed to overlap at least a portion of pattern image 32p so as to impair the visibility of pattern image 32p. Furthermore, at position P3, which is a non-reconstructed image viewing angle region and a regular reflection region, pattern image 31q is not visible, and foreground portion 32a and background portion 32b can be distinguished, and pattern image 32p is observed as a whole (state #19).

In this way, the hologram layer 31 and the transparent layer 32 can be made to look different, with the image of the hologram layer 31 and the image of the transparent layer 32 being visible or invisible depending on the observation angle, by using ink for the transparent layer 32 that reflects different amounts of light depending on the observation angle. Moreover, the hologram layer 31 is provided with a pattern image 31r composed of a decorative design and a pattern image 32q of a two-dimensional code that is a meaningless image at first glance and does not have a decorative design. Therefore, in the reconstructed image viewing angle region of the hologram layer 31, the visibility of the pattern image 31r composed of a decorative design in the hologram layer 31 can be prevented from being impaired, regardless of whether the pattern image 32p of the transparent layer 32 is visible or not.

(b) Configuration of the printed matter of the second embodiment Next, a second embodiment of the printed matter of the present disclosure will be described. The printed matter 10a according to the second embodiment has the same configuration as the printed matter 10 according to the first embodiment shown in Fig. 2. That is, the only difference between the printed matter 10a and the printed matter 10 is the difference between the information recording medium 30a and the information recording medium 30 described above.

(c) Example (information recording body)
A method of implementing the information recording medium of this embodiment using the above-described technology will be described below. FIG. 5 is a diagram showing an example of a pattern image of the information recording body 30a according to this embodiment. 6 to 9 are diagrams for explaining the spatial frequency domain F when the pattern image according to the present embodiment is subjected to frequency conversion.

(i) Example 1
First, according to the method for creating a hologram layer described in Japanese Patent No. 5742518, a PET film with a thickness of 4.5 μm (Lumirror (registered trademark) manufactured by Toray Industries, Inc.) is used as a supporting base material, and one of the A laminate for an information recording medium was created by sequentially laminating a resin layer for forming a hologram and a metal reflective layer on the surface. Furthermore, the laminate is printed using a transparent medium ink by gravure printing so that the background area has a dot area ratio of 25% and the foreground area has a dot area ratio of 100%, and is heated and dried. The information record body was completed.

The hologram is designed to be a reflective relief hologram in which, when the light incidence angle is 45°, the amount of light is maximum when the reconstructed light angle is 35°, and a hologram reconstruction image can be displayed when the angle is between 30° and 40°. As described below, in addition to a decorative design, the hologram has an image C1 (first image) formed therein, which is meaningless to a person at first glance, and an image C2 (second image) similarly meaningless to a person at first glance formed in the transparent layer, and both images are created to have an overlapping area when viewed in a plane on the information recording medium.

FIG. 5A shows an enlarged view of an image C1 (first image) exemplified by the pattern image 31q of the hologram layer 31 and a region E1 that is a part of the image C1. The hologram layer 31 is a layer on which an image C1 is formed. The image C1 is a pattern image in which a foreground portion C1a and a background portion C1b are expressed in binary values, as shown in the area E1. FIG. 5B shows an enlarged image of an image C2 (second image) exemplified by the image 32p of the transparent layer 32 and a region E2 that is a part of the image C2. The transparent layer 32 is a layer on which the image C2 is printed. The image C2 is a pattern image in which a foreground portion C2a and a background portion C2b are expressed in binary values, as shown in a region E2. The dot area ratio of the foreground portion C2a and the background portion C2b is the same as that of the foreground portion 32a and the background portion 32b described in the example of FIG. In this way, since the image C1 of the hologram layer 31 and the image C2 of the transparent layer 32 of the information recording body 30a are pattern images, they are meaningless images when a person just looks at them.

6(a) shows a spatial frequency domain F1 obtained by frequency-converting an image C1 of the hologram layer 31 by performing a Fourier transform. In the spatial frequency domain F1, a shape represented by a plurality of feature points represented by the frequency conversion of the image C1 is formed as a repeating shape T1 (first shape) which is a plurality of circumferences with different radii with an origin O1. FIG. 6(b) shows a spatial frequency domain F2 obtained by frequency-converting an image C2 of the transparent layer 32 by performing a Fourier transform. In the spatial frequency domain F2, a shape represented by a plurality of feature points represented by the frequency conversion of the image C2 is formed as a repeating shape T2 (second shape) which is a plurality of circumferences with different radii with an origin O2. The repeating shape T2 is meaningful as a code. In this way, the repeating shape T1 and the repeating shape T2 are the same circumference shape. In this example, the repeating shape T2 has a wider interval between adjacent diameters than the repeating shape T1.

Figure 6(c) shows the spatial frequency domain F obtained by frequency conversion by performing a Fourier transform on the composite image of the image C1 of the hologram layer 31 shown in Figure 5(a) and the image C2 of the transparent layer 32 shown in Figure 5(b). The repeating shape T0 shown in the spatial frequency domain F shown in Figure 6(c) is a circular shape composed of the repeating shapes T1 and T2, which are multiple circumferences with different radii and have an origin O. Therefore, just by looking at the repeating shape T0, it is not possible to distinguish between the repeating shapes T1 and T2, and it is not possible to know which one it is. Therefore, it is not possible to infer the code indicated by the shape represented by the feature points that make up the repeating shape T2 from the spatial frequency domain F.

Regarding the information recording medium created under the above conditions, the incident angle α of the illumination light source 21 in FIG. 3(b) was set to 45°. In addition, β1 is set as 35° as the angle corresponding to position P1, β2 is set as 40° as the angle corresponding to position P2, and β3 is set as 45° as the angle corresponding to position P3. Visibility was confirmed visually. As a result, at position P1, the hologram design and image C1 (first image) could be seen very clearly, but the transparent layer image C2 (second image) could not be seen at all. Next, at position P2, the hologram design and image C1 (first image) were sufficiently visible, although the brightness was slightly lower than that at position P1. Furthermore, since the image C2 (second image) of the transparent layer was also visible to some extent, the image C1 and the image C2 were visually recognized as a composite image, and could not be distinguished as separate images. Furthermore, at position P3, the hologram design and image C1 (first image) were not visible at all, but on the contrary, in image C2 (second image) of the transparent layer, the contrast between the background and foreground areas was clear, I was able to clearly confirm this.

(ii) Example 2-1
In this example and subsequent examples, the description of the difference in appearance between the hologram image C1 and the transparent layer image C2 depending on the angle of the illumination light source and the position of the observation angle is the same, so the description thereof will be omitted. . FIG. 7A shows a spatial frequency region F1 that is frequency-converted by performing Fourier transform on a certain pattern image of the hologram layer 31 (not shown). In the spatial frequency domain F1, a shape (first shape) represented by a plurality of feature points D1, which is represented by frequency-converting the pattern image of the hologram layer 31, is placed on the circumferential shape T11 (specific position). It is formed. FIG. 7B shows a spatial frequency region F2 obtained by frequency-converting a pattern image of the transparent layer 32 (not shown) which is different from the pattern image of the hologram layer 31 by performing Fourier transform. In the spatial frequency domain F2, a shape (second shape) represented by a plurality of feature points D2, which is represented by frequency-converting the pattern image of the transparent layer 32, is placed on the circumferential shape T12 (specific position). It is formed. Note that the shape represented by the feature point D2 is meaningful as a code.

Figure 7 (c) shows a spatial frequency domain F obtained by frequency conversion by performing a Fourier transform on a composite image including a pattern image of the hologram layer 31 and a pattern image of the transparent layer 32. The circumferential shape T10 shown in the spatial frequency domain F shown in Figure 7 (c) is a circumference with the same radius as the circumferential shapes T11 and T12. The shape represented by the characteristic point D0 on the circumferential shape T10 is the same as the shape represented by the characteristic point D1 shown in Figure 7 (a). Therefore, as far as the circumferential shape T10 is concerned, it is not possible to determine the shape represented by the characteristic point D2, including its presence or absence. Therefore, it is not possible to estimate the code represented by the shape represented by the characteristic point D2 on the circumferential shape T12 from the spatial frequency domain F.

Note that the circumferential shapes T11, T12, and T10 shown in FIG. 7 are merely images and are not actually shown. In addition, in the above-mentioned Example 2-1, the characteristic point D2 coincides with the characteristic point D1, but this is not limited to this. The characteristic point D1 and the characteristic point D2 may not coincide.

(iii) Example 2-2
Next, cases where feature points do not match will be described.
FIG. 8(a) shows a spatial frequency domain F1 in which a certain pattern image of a hologram layer 31 (not shown) is frequency-converted by performing a Fourier transform. In the spatial frequency domain F1, a shape (first shape) represented by a plurality of feature points D1-2 represented by frequency-converting the pattern image of the hologram layer 31 is formed on a circumferential shape T11-2 (specific position). FIG. 8(b) shows a spatial frequency domain F2 in which a certain pattern image of a transparent layer 32 (not shown) different from the pattern image of the hologram layer 31 is frequency-converted by performing a Fourier transform. Here, an example will be described in which the certain pattern image is the same as the image in FIG. 7(b). In the spatial frequency domain F2, a shape (second shape) represented by a plurality of feature points D2-2 represented by frequency-converting the pattern image of the transparent layer 32 is formed on a circumferential shape T12-2 (specific position). Note that the shape represented by the feature points D2-2 is meaningful as a code.

Figure 8 (c) shows a spatial frequency domain F obtained by frequency conversion by performing a Fourier transform on a composite image including a pattern image of the hologram layer 31 and a pattern image of the transparent layer 32. The circumferential shape T10-2 shown in the spatial frequency domain F shown in Figure 8 (c) is a circumference with the same radius as the circumferential shape T11-2 and the circumferential shape T12-2. Therefore, even if the characteristic point D1-2 and the characteristic point D2-2 do not match, the characteristic point D1-2 and the characteristic point D2-2 cannot be distinguished from each other by looking at the circumferential shape T10-2. Therefore, the code indicated by the shape represented by the characteristic point D2-2 on the circumferential shape T12-2 cannot be estimated from the spatial frequency domain F. Note that the circumferential shapes T11-2, T12-2, and T10-2 shown in Figure 8 are the same as those in Figure 7, and all of them are images and are not actually represented.

(iv) Example 3
FIG. 9A shows a spatial frequency domain F1 in which a frequency conversion is performed by performing a Fourier transform on yet another pattern image of the hologram layer 31 (not shown). In the spatial frequency domain F1, a shape (first shape) represented by a plurality of feature points G1 represented by frequency conversion of the pattern image of the hologram layer 31 is formed on a lattice shape T21 (specific position). FIG. 9B shows a spatial frequency domain F2 in which a frequency conversion is performed on yet another pattern image of the transparent layer 32 (not shown), which is different from the pattern image of the hologram layer 31, is performed a Fourier transform. In the spatial frequency domain F2, a shape (second shape) represented by a plurality of feature points G2 represented by frequency conversion of the pattern image of the transparent layer 32 is formed on a lattice shape T22 (specific position). Note that the shape represented by the feature points G2 has meaning as a code.

FIG. 9C shows a spatial frequency domain F obtained by frequency-converting a composite image including a pattern image of the hologram layer 31 and a pattern image of the transparent layer 32 by performing Fourier transform. The grating shape T20 expressed in the spatial frequency domain F shown in FIG. 9(c) is the same grating shape as the grating shape T21 and the grating shape T22. The shape represented by the feature point G0 on the grid shape T20 is the shape represented by the feature point G1 shown in FIG. 9(a), and the shape represented by the feature point G2 shown in FIG. 9(b). are partially overlapped. Therefore, it is not possible to determine whether the shape represented by the feature point G0 is the shape represented by the feature point G1 or the shape represented by the feature point G2. Therefore, as long as the grid shape T20 is viewed, the shape represented by the feature point G2 cannot be determined. Therefore, from the spatial frequency domain F, the code indicated by the shape represented by the feature points G2 on the lattice shape T22 cannot be estimated.

(v) Reading Device Next, a reading device 5 that reads a code formed on the information display body 30a as exemplified in the above-mentioned Examples 1, 2-1, 2-2, and 3 will be described. Fig. 10 is a functional block diagram of the reading device 5 according to this embodiment. The reading device 5 is, for example, a personal computer to which a scanner is connected. The reading device 5 includes a control unit 50, a storage unit 60, a reading unit 65, an operation unit 67, and a display unit 68.

The control unit 50 is a CPU (Central Processing Unit) that controls the entire reading device 5. The control unit 50 reads and executes the OS (Operating System) and application programs stored in the storage unit 60 as appropriate, thereby working with the above-mentioned hardware to perform various functions.

The control unit 50 includes an image reception unit 51, a frequency conversion unit 52, an analysis unit 53 (feature point acquisition unit), and a code identification unit 54.

The image receiving unit 51 receives image data from the information recording medium 30a via the reading unit 65 as the reading unit 65 reads the information recording medium 30a.

The frequency conversion unit 52 performs frequency conversion on the image data received by the image reception unit 51 by decomposing the image data into each frequency component using Fourier transform and converting the data into a spatial frequency domain F.

The analysis unit 53 acquires feature points displayed in the spatial frequency domain F.

The code identification unit 54 refers to the code table 62 and identifies the code from the feature points acquired by the analysis unit 53.

The storage unit 60 is a storage area such as a hard disk or a semiconductor memory device for storing programs, data, etc. necessary for the control unit 50 to execute various processes.

Note that a computer refers to an information processing device equipped with a control unit, a storage device, etc., and the reading device 5 is an information processing device equipped with a control unit 50, a storage unit 60, etc., and is included in the concept of a computer. The storage unit 60 stores a conversion program 61 and a code table 62. The conversion program 61 is a program for executing each function of the control unit 50. The code table 62 is a table that associates the arrangement position of each feature point with a code. The arrangement position of each feature point corresponds to the arrangement position of the feature point that appears in the spatial frequency domain F2 obtained by frequency converting the pattern image of the transparent layer 32.

The reading unit 65 is, for example, a scanner, and is a device that reads printed content such as images and characters.

The operation unit 67 is, for example, a keyboard or mouse, and is a device for the user to input.

The display unit 68 is, for example, a liquid crystal display device. Note that the operation unit 67 and the display unit 68 may be a device having both functions, such as a touch panel display, for example.

(vi) Processing of the reading device Next, processing of the reading device 5 will be explained. FIG. 11 is a flowchart showing code identification processing in the reading device 5 according to this embodiment. In step S (hereinafter simply referred to as "S") 10, the control section 50 of the reading device 5 activates the reading section 65.

In S11, the control unit 50 (image reception unit 51) reads the image via the reading unit 65. Here, the user can read the image using the reading unit 65 from an angle that allows only the pattern image of the transparent layer 32 of the information recording body 30a to be read. Further, the user can read the image using the reading unit 65 from an angle that allows only the pattern image of the hologram layer 31 of the information recording body 30a to be read. Furthermore, the user can read the image using the reading unit 65 from an angle that allows the pattern image of both the hologram layer 31 and the transparent layer 32 of the information recording body 30a to be read.

In S12, the control unit 50 (frequency conversion unit 52) performs Fourier transformation (frequency conversion processing) on the read image.

In S13, the control unit 50 (analysis unit 53) acquires feature points in the spatial frequency domain F.

In S14, the control unit 50 (code identifying unit 54) refers to the code table 62 and determines whether the code corresponding to the acquired feature point has been identified. If there is a code in the code table 62 that matches the arrangement position of the acquired feature point, the code can be identified. If the code has been identified (S14: YES), the control unit 50 moves the process to S15. On the other hand, if the code cannot be identified (S14: NO), the control unit 50 moves the process to S16.

In S15, the control unit 50 causes the display unit 68 to display a message indicating that the code has been identified. The control unit 50 then ends this process.

On the other hand, in S16, the control unit 50 causes the display unit 68 to display an error message. After that, the control unit 50 ends this process.

Here, when the reading section 65 reads the image from an angle that allows reading only the pattern image of the transparent layer 32, the control section 50 obtains only the pattern image of the transparent layer 32. The code corresponding to the pattern image of the transparent layer 32 is stored in the code table 62. Therefore, the control unit 50 can identify the code in the process of S14 (S14: YES).

On the other hand, the reading unit 65 may read the image from an angle that allows the pattern images of both the transparent layer 32 and the hologram layer 31 to be read, or the reading unit 65 may read the image from an angle that allows only the pattern image of the hologram layer 31 to be read. In the case of reading, the control unit 50 does not obtain only a pattern image of the transparent layer 32. The code table 62 stores only the codes corresponding to the pattern images of the transparent layer 32, and the codes corresponding to the pattern images of the hologram layer 31 and the pattern images of both the transparent layer 32 and the hologram layer 31 are stored in the code table 62. Not remembered. Therefore, the control unit 50 cannot specify the code corresponding to the acquired feature point in S14 (S14: NO).

(vii) Regarding copies of information recording bodies Next, a case where the information recording body 30a is duplicated will be described. FIG. 12 is a diagram for explaining the positional relationship between the illumination light source 21 and the camera 23 when copying the information recording medium 30a according to this embodiment. FIG. 14(a) is a diagram for explaining a printed matter 45 that is a copy of the information recording body 30a according to this embodiment. 12(a) and 12(b) show the positional relationship between the illumination light source 21, camera 23, and information recording body 30a of a duplication machine such as a copying machine. An image of the information recording body 30a is captured by the camera 23 while being irradiated with light from the illumination light source 21 shown in FIG. 12(a) or FIG. 12(b).

Figure 12(a) shows a case where the illumination light source 21 and camera 23 are positioned perpendicular to the information recording medium 30a, and the camera 23 captures an image. Figure 12(b) shows a case where the illumination light source 21 illuminates the information recording medium 30a from a slightly oblique direction, and the camera 23 captures an image perpendicular to the information recording medium 30a. In either case, it can be said that the camera 23 is highly likely to capture images of both the hologram layer 31 and the transparent layer 32 of the information recording medium 30a, depending on the positional relationship between the illumination light source 21 and the information recording medium 30a.

The positional relationship between the camera 23, the illumination light source 21, and the information recording body 30a is adjusted to a non-reproduced image viewing angle region of the image of the hologram layer 31, and to a specular reflection region or a region near specular reflection of the image of the transparent layer 32. Alternatively, it is generally difficult to adjust the reproduction image viewing angle region of the image of the hologram layer 31 to the non-specular reflection region of the image of the transparent layer 32. In this way, based on the image obtained by the camera 23, the copying machine produces a printed material 45, which is a copy of the information recording material 30a.

The printed body 45, which is a copy of the information recording body 30a shown in the cross-sectional view of FIG. 14(a), has a composite image of the pattern image of the hologram layer 31 of the information recording body 30a and the pattern image of the transparent layer 32. As shown in FIG. 14(a), the printed body 45 has an ink layer 43. The ink layer 43 is a layer made of a typical black ink containing carbon. Therefore, when the printed body 45 is observed from any observation angle (reconstructed image viewing angle area, regular reflection area, etc.), only the composite image is visible.

When the printed material 45, which is a copy, is read using the above-mentioned reading device 5, no matter what reading angle the reading section 65 is set to, the control section 50 determines whether the hologram layer 31 of the information recording material 30a is A composite image of the pattern image of the transparent layer 32 and the pattern image of the transparent layer 32 is obtained. Therefore, the control unit 50 cannot read the code corresponding to the pattern image included in the transparent layer 32 of the information recording body 30a from the printed body 45.

As described above, the present embodiment has the following effects. First of all, the information recording body 30a has a composite image of the image C1 and the image C2. Then, in images C1 and C2, the regularity of the feature points expressed in the spatial frequency domain F2 obtained by frequency-converting the image C2 is obstructed by the feature points expressed in the spatial frequency domain F1 obtained by frequency-converting the image C1. It is related. Therefore, when both image C1 and image C2 can be recognized, image C2 cannot be estimated from the feature points expressed in the spatial frequency domain F obtained by frequency-converting the composite image of image C1 and image C2. You can do it like this.

Secondly, the repeating shape T1 represented by feature points represented in the spatial frequency domain F1 obtained by frequency-converting image C1 on the information recording medium 30a and the repeating shape T2 created from feature points represented in the spatial frequency domain F2 obtained by frequency-converting image C2 are similar shapes. Therefore, when both image C1 and image C2 are recognizable, it is possible to make it impossible to estimate image C2 from feature points represented in the spatial frequency domain F obtained by frequency-converting a composite image of image C1 and image C2.

Thirdly, the feature points represented in the spatial frequency domain F2 obtained by frequency-converting the image C2 of the information recording medium 30a can indicate a code. Therefore, when both the image C1 and the image C2 printed on the information recording medium 30a can be recognized, it is possible to make it impossible to infer the code from the feature points represented in the spatial frequency domain F obtained by frequency-converting the composite image of the images C1 and C2. In particular, the copy 40 obtained by copying the information recording medium 30a allows the composite image of the images C1 and C2 to be recognized from any observation angle, so it is possible to make it impossible to infer the code from the copy 40. Therefore, the information recording medium 30a can be used, for example, for authenticity determination.

Fourth, since the image C1 is possessed by the hologram layer 31 and the image C2 is possessed by the transparent layer 32, it is possible to switch between the image C1 and the image C2 for observation depending on the observation angle of the information recording body 30a. . Furthermore, since the transparent layer 32 can be produced using transparent ink or the like, it can be printed at low cost.

Fifthly, by reading information recording medium 30a with reading device 5 at an observation angle where only image C2 is visible, reading device 5 can read the code represented by feature points shown in spatial frequency domain F2 obtained by frequency-converting image C2. Furthermore, when reading printed material 45, which is a copy of information recording medium 30a where only a composite image consisting of images C1 and C2 can be observed, reading device 5 reads feature points shown in spatial frequency domain F obtained by frequency-converting the composite image, making it possible to make it impossible to read the code from the read feature points.

In addition, in the information recording body 30 of the first embodiment, the pattern image 32p of the transparent layer 32 is the same as the above-described image C2. Therefore, if the pattern image 31p based on the design of the hologram layer 31 can constitute the above-mentioned image C1, all the above-mentioned effects can be achieved in the same way. Further, even if the pattern image 31p does not constitute the above-described image C1, at least the fourth and fifth effects described above can be achieved because the transparent layer 32 has the above-mentioned image C2.

(d) Example (printed matter)
Next, a method for producing a printed matter according to the present embodiment using the above-mentioned technology will be described below, and explanations of overlapping points will be omitted as appropriate.

(i) Example 4
First, white coated paper was used as the paper. Next, in accordance with the method of creating a hologram layer described in Japanese Patent No. 5742518, a PET film (Lumirror (registered trademark) manufactured by Toray Industries, Inc.) having a thickness of 4.5 μm was used as a support substrate, and a peeling layer, a resin layer forming a hologram, a metal reflective layer, and an adhesive layer were sequentially laminated on one side of the support substrate. This was used as a transfer foil film, and the laminate other than the support substrate and the peeling layer was thermally transferred to paper by applying a hot stamping tool to a predetermined area. Furthermore, on the laminate after transfer, a medium ink made of a transparent material was printed by gravure printing so that the dot area rate of the background part was 25% and the dot area rate of the foreground part was 100%, and the laminate was heated and dried to complete a printed matter having an information recording body. That is, the information recording body according to the above-mentioned Example 1 was formed on the printed matter.

The hologram and transparent layer in the printed matter of this embodiment have the same optical characteristics as those described in the first embodiment. In addition, the effect of performing a Fourier transform on the composite image of the image C1 of the hologram layer 31 and the image C2 of the transparent layer 32 to obtain a spatial frequency domain F that is frequency-converted, and the effect of being unable to infer the code indicated by the shape represented by the feature points that constitute the repetitive shape T2 from the spatial frequency domain F, similar to the first embodiment, is also provided.

(ii) Examples 5-1, 5-2 and 6
Examples 5-1, 5-2, and 6 relate to printed materials provided with the information recording bodies according to Examples 2-1, 2-2, and 3 described above, respectively. Therefore, the various functions and effects of the information recording bodies according to Examples 2-1, 2-2, and 3 are the same as those of printed matter equipped with the information recording bodies according to Examples 5-1, 5-2, and 6. The detailed explanation will be omitted because it is the action and effect that it has.

(iii) Reading device Next, the contents and effects of the reading device 5 that reads the code in the printed matter 10a having the information display body 30a on which the code is formed as exemplified in the above-mentioned Examples 4, 5-1, 5-2 and 6 are common to the contents and effects of the reading device 5 related to the information recording body 30a described above, and therefore a detailed explanation will be omitted.

(iv) Processing of the reading device The contents and effects of the processing of the reading device 5 that reads the code from the information recording body 30a of the printed matter 10a are as follows. Since this is the same as the explanation, detailed explanation will be omitted.

(v) Regarding copies of printed matter Next, a case where the printed matter 10a is duplicated will be described. FIG. 13 is a diagram for explaining the positional relationship between the illumination light source 21 and the camera 23 when copying the printed matter 10a according to the present embodiment. FIGS. 14(b) and 14(c) are diagrams for explaining a copy 40 of the printed matter 10a according to the present embodiment. 13(a) and 13(b) show the positional relationship between the illumination light source 21, camera 23, and printed matter 10a of a duplication machine such as a copying machine. An image of the information recording body 30a of the printed matter 10a is captured by the camera 23 while being irradiated with light from the illumination light source 21 shown in FIG. 13(a) or FIG. 13(b).

FIG. 13A shows a case where the illumination light source 21 and the camera 23 are positioned perpendicularly to the information recording medium 30a, and the camera 23 acquires an image. Further, FIG. 13(b) shows a case where the illumination light source 21 irradiates the information recording body 30a from a slightly oblique direction, and the camera 23 captures the image from a direction perpendicular to the information recording body 30a. . In either case, there is a high possibility that the camera 23 will capture images of both the hologram layer 31 and the transparent layer 32 of the information recording body 30a, depending on the positional relationship between the illumination light source 21 and the information recording body 30a. I can say that.

The positional relationship between the camera 23, the illumination light source 21, and the information recording body 30a is adjusted to a non-reproduced image viewing angle region of the image of the hologram layer 31, and to a specular reflection region or a region near specular reflection of the image of the transparent layer 32. Alternatively, it is generally difficult to adjust the reproduction image viewing angle region of the image of the hologram layer 31 to the non-specular reflection region of the image of the transparent layer 32. In this way, based on the image obtained by the camera 23, the copying machine produces a copy 40 of the printed matter 10.

The copy 40 shown in FIG. 14(b) has a print 45 at a position corresponding to the information recording medium 30a (see FIG. 2(a)) of the printed matter 10a. This print 45 has a composite image of the pattern image of the hologram layer 31 of the information recording medium 30a and the pattern image of the transparent layer 32. FIG. 14(c) is a cross-sectional view of the print 45 corresponding to FIG. 2(b). As shown in FIG. 14(c), the print 45 has an ink layer 43. The ink layer 43 is a layer made of a typical black ink containing carbon. Therefore, when the print 45 is observed from any observation angle (reconstructed image viewing angle area, regular reflection area, etc.), only the composite image is visible.

When the printed material 45 of the copy product 40 is read using the above-mentioned reading device 5, no matter what reading angle the reading portion 65 is set to, the control portion 50 controls whether the hologram layer 31 of the information recording material 30 is A composite image of the pattern image of the transparent layer 32 and the pattern image of the transparent layer 32 is obtained. Therefore, the control unit 50 cannot read the code corresponding to the pattern image included in the transparent layer 32 of the information recording body 30a from the printed body 45.

In this way, the printed matter of this embodiment has various effects similar to those of the information recording medium itself described above.

3. Modifications The information recording medium of the present disclosure is not limited to the first embodiment or the second embodiment described above, and includes various modifications without departing from the gist of the present disclosure. Hereinafter, several modified examples will be described as examples thereof.

(a) Modification 1
15A is a cross-sectional view corresponding to FIG. 2 for explaining the layer structure of an information recording medium 30b according to Modification 1 of the first and second embodiments of the present disclosure. The information recording medium 30b according to Modification 1 differs from the information recording mediums 30 and 30a of the first and second embodiments in that the arrangements of the substrate 33 and the transparent layer 32 are interchanged. That is, the information recording medium 30b has a structure in which the adhesive layer 34, the hologram layer 31, the transparent layer 32, and the substrate 33 are laminated in this order from the side closest to the paper 11 of the printed matter.

In particular, in the case of this modified example, the refractive index of the substrate 33 is preferably smaller than the refractive index of the transparent layer 32 formed below it, in the range of 0.1 to 0.4. In this case, light that passes through the substrate 33 from the outside and is incident on the transparent layer 32 is likely to be totally reflected at the interface between the substrate 33 and the transparent layer 32 below it. This is because the reflected light from the transparent layer 32 increases, making the pattern image made of transparent ink easier to see or easier to read by a reading device.

It goes without saying that the information recording medium 30b according to the first modified example has the same effects as those of the first and second embodiments. Furthermore, the outermost surface of the information recording medium 30b opposite the paper 11 is the base material 33 rather than the transparent layer 32. This prevents the transparent layer 32 from being damaged by friction or external force caused by foreign matter from the outside, which can impair the visibility of the pattern image and the reading accuracy of the reading device.

In addition, in the unlikely event that an attempt is made to forge the image formed on the transparent layer 32 of the information recording medium 30b, it is necessary to first peel off the base material 33 laminated on its upper surface, and peeling off the base material 33 increases the possibility that the transparent layer 32 will be destroyed. This enhances the effect of preventing forgery in that traces of forgery are more likely to remain. On the other hand, the base material 33 may be further laminated on the upper surface of the transparent layer 32, which is the outermost surface of the information recording medium 30, 30a of the first and second embodiments. In this case as well, the protective effect of the transparent layer 32 is enhanced, and as long as the base material 33 has a certain degree of transparency, it is possible to achieve the effects of the first and second embodiments as they are.

(b) Modification 2
Next, an information recording body 30c according to a second modification of the first and second embodiments of the present disclosure will be described. FIG. 15(b) is a cross-sectional view illustrating a transfer foil film 100 for thermally transferring an information recording body 30c according to modification example 2 to a sheet of paper 11 or the like. Further, FIG. 15(c) is a cross-sectional view corresponding to FIG. 2, showing the state of the information recording body 30c after being thermally transferred onto the paper 11 using the transfer foil film 100 shown in FIG. 15(b). .

As shown in FIG. 15(b), in the transfer foil film 100, a release layer 35 having release properties such as silicone resin is formed on one side of a support base material 36, and further, adjacent to the release layer 35, a release layer 35 is formed. , a hologram layer 31 composed of a resin layer 31a and a reflective layer 31b are laminated. Further, an adhesive layer 34 is laminated on the side of the hologram layer 31 opposite to the release layer 35. Usually, in order to maintain the adhesion of the transfer foil film 100 when not in use, a release paper or the like having releasability is laminated on the exposed surface side of the adhesive layer 34.

Next, the process of transferring the information recording body 30c to the paper 11 using the above-mentioned transfer foil film 100 will be described. First, the surface of the adhesive layer 34 of the transfer foil film 100 is placed on one side of the paper 11 so that it abuts against the surface. Then, a hot stamp tool prepared in a shape corresponding to the contour shape of the information recording body 30c to be transferred is pressed against the surface of the support substrate 36 opposite the peeling layer 35, and a predetermined heat pressure is applied for a predetermined time, so that the laminate of the adhesive layer 34, the hologram layer 31, and the transparent layer 32 is thermally transferred to the paper 11 as a part of the transfer foil film 100, as shown in FIG. 15(c). Here, since the adhesive layer 34 is formed of a thermoplastic or thermosetting resin, the laminate can be easily transferred to a predetermined location on the paper 11. In addition, the untransferred area of the transfer foil film 100, the peeling layer 35, and the support substrate 36 are not transferred and are peeled off from the paper 11 side.

Note that in order to make it easier to visually recognize the pattern image composed of the ink of the transparent material forming the transparent layer 32 or to make it easier to read by a reading device, the refractive index of the peeling layer 35 is arranged on the lower layer side. It is preferable that the refractive index of the transparent layer 32 has a difference of 0.1 or more and 0.4 or less. In particular, it is preferable that the refractive index of the release layer 35 is smaller than the refractive index of the transparent layer 32 disposed below it, in the range of 0.1 or more and 0.4 or less. In this case, light that passes through the release layer 35 from the outside and enters the transparent layer 32 is likely to be totally reflected at the interface between the release layer 35 and the transparent layer 32 below it. This is because the amount of light reflected from the transparent layer 32 increases, making it easier to visually recognize the pattern image made of ink on the transparent material or to read it with a reading device.

In this way, by using a method of thermally transferring the information recording body 30c from the transfer foil film 100 to the paper 11, the thickness of the hologram layer 31 and the transparent layer 32 in particular can be made even thinner. As a result, the overall thickness of the information recording body 30c can be made thinner. This increases the likelihood of brittle fracture of the hologram layer 31 and the transparent layer 32 when forging, for example, by peeling the information recording body 30c off the paper 11 and replacing it with another information recording body, making forgery even more difficult. In addition, by forming information recording bodies on both the front and back sides of the paper 11, restrictions on the specifications and formation locations of the paper 11 can be reduced, and the freedom in the formation locations and number of information recording bodies can be increased.

(c) Modification 3
Furthermore, although not shown, an information recording medium according to the third modified example of the first and second embodiments of the present disclosure will be described. In this modified example, a material that emits visible light when excited by infrared or ultraviolet light, which is an authenticity determining material, is mixed into at least a part of the ink that forms the transparent layer 32 of the information recording medium, to form an ink of a transparent material. That is, when the ink that forms the transparent layer 32 is irradiated with light in the infrared or ultraviolet wavelength range, electrons in the illuminant contained in the ink are excited, and when the excited electrons return to the ground state, they emit excess energy as visible light. Note that the wavelength range of the infrared light referred to here can be, for example, 0.78 μm or more and 1 mm or less, and the wavelength range of the ultraviolet light can be, for example, 0.01 μm or more and 0.38 μm or less. However, even if the ink has a wavelength range longer than infrared light or shorter than ultraviolet light, there is no problem as long as it emits visible light, so it may be excited by, for example, terahertz waves, millimeter waves, X-rays, gamma rays, etc.

Materials that are excited by infrared radiation and emit visible light are also called upconversion emitters, such as erbium (Er), holmium (Ho), praseodymium (Pr), thulium (Tm), neodymium (Nd), and gadolinium. (Gd), europium (Eu), samarium (Sm), terbium (Tb), dysprosium (Dy), and cerium (Ce). Examples include those in which the base material is a halide or the like. In addition, although there are some materials that overlap with those mentioned above, examples include materials disclosed in Japanese Patent Application Laid-Open No. 7-297475.

Materials that are excited by ultraviolet light and emit visible light include, for example, dyes such as fluorescein-based fluorescent dyes, coumarin-based fluorescent dyes, and rhodamine-based fluorescent dyes, and inorganic pigments such as europium-manganese-activated barium magnesium aluminate, manganese-activated zinc silicate, europium-activated yttrium oxide, europium-activated yttrium sulfide, zinc oxide, manganese-activated zinc germanate, and europium-activated yttrium phosphovanadate.

Note that when the transparent layer 32 has a foreground portion 32a and a background portion 32b as described in the first embodiment, for example, the foreground portion 32a has a halftone area ratio of 100%, and the background portion 32b has a dot area ratio of 100%. In this case, the ink of the transparent material described above may be used for both the foreground portion 32a and the background portion 32b, such as by printing with a dot area ratio of 25%. In addition, when the transparent layer 32 is a pattern image consisting only of the foreground part, the printing area of the above-mentioned image C2 is printed with a halftone dot area ratio of 100%, and the printing area and the non-printing area are divided into two areas. The pattern image can be expressed as a value. At this time, it is possible to use the above-mentioned ink of the transparent material in the printing area of the image C2, but conversely, it is also possible to use the ink of the above-mentioned transparent material only in the non-printing area of the image C2. be.

In this way, by making the ink forming the transparent layer 32 of the information recording medium out of a transparent ink that is excited by infrared or ultraviolet light and emits visible light, it is possible to improve the accuracy of the counterfeit prevention function of the present disclosure and to complement it, utilizing the difference in appearance between the image of the hologram layer 31 and the image of the transparent layer 32 due to the relationship between the irradiation angle of visible light and the observation angle. That is, in addition to the difficulty of copying the embedded information under the condition of visible light irradiation, the visibility of the image of the transparent layer 32 can be increased only when irradiated with infrared or ultraviolet light in a specific wavelength range, with almost no influence from the image of the hologram layer 31. This can ensure one more layer of difficulty in copying the embedded information. Note that the ink of the transparent material may be made by mixing both a material that is excited by infrared light and emits visible light, and a material that is excited by ultraviolet light and emits visible light. This can ensure even more difficulty in copying the embedded information.

(d) Modification example 4
Next, although not shown in the drawings, an information recording body according to a fourth modification of the first and second embodiments of the present disclosure will be described. In this modification, an infrared absorbing material, which is an authentication material, is mixed into at least a part of the ink forming the transparent layer 32 of the information recording medium to form an ink made of a transparent material. Examples of organic dyes that absorb in the infrared wavelength region include polymethylene-based, phthalocyanine-based, azo-based, and anthraquinone-based compounds, and examples of inorganic infrared absorbers include antimony-doped tin oxide and tin-doped indium oxide. It will be done.

When the transparent layer 32 has a foreground portion 32a and a background portion 32b, or when the transparent layer 32 is a pattern image consisting of only a foreground portion, the configuration is the same as that of the above-mentioned modified example 3.

In this way, by making the ink forming the transparent layer 32 of the information recording medium out of a transparent ink containing an infrared absorbing material, as in the third modification, it is possible to improve the accuracy of the anti-counterfeiting function of the present disclosure and complement it by utilizing the difference in appearance between the image of the hologram layer 31 and the image of the transparent layer 32 due to the relationship between the irradiation angle of visible light and the observation angle. That is, in addition to the difficulty of duplicating the embedded information under visible light irradiation conditions, the image of the transparent layer 32 can be clearly recognized by a measuring means such as an infrared camera only when irradiated with infrared light in a specific wavelength range, with almost no influence from the image of the hologram layer 31. This can ensure that the embedded information is difficult to duplicate in one layer.

(e) Modification 5
Further, an information recording medium according to Modification 5 of the first and second embodiments of the present disclosure will be described. In this modification, at least a part of the ink forming the transparent layer 32 of the information recording medium is made of a transparent ink containing a polarizing material, which is an authenticity determining material. Examples of such polarizing materials include an absorption type polarizer obtained by impregnating iodine or a dichroic dye into polyvinyl alcohol and stretching and aligning it, an absorption type polarizer obtained by aligning a dichroic dye on an alignment film, a reflective type circular polarizer in which cholesteric liquid crystal is oriented on a substrate, and a reflective type polarizer formed by laminating birefringent multilayer films. In addition to these, any element having the property of being able to extract a polarized component in a specific direction from reflected light or transmitted light can be used.

Such a transparent layer 32 containing a polarizing material can be formed, for example, by the method described in Japanese Patent No. 6519582. First, an alignment film solution is prepared by dissolving an alignment film resin, and this is applied to the substrate 33 by the microgravure method while masking areas other than a predetermined pattern image to form a coating film. Next, an alignment process is performed by rubbing the coating film in a predetermined direction with a rubbing cloth, and an alignment film is obtained. Furthermore, a dichroic dye is added to a UV-curable liquid crystal to prepare a polarizer solution.

Thereafter, using a microgravure method, a polarizer solution is applied onto the alignment film to a predetermined thickness to form a coating film. Next, the coating film is annealed, and the coating film is irradiated with UV in an oxygen atmosphere to harden the coating film, thereby creating a polarizing function with a transmission axis in a predetermined direction. A transparent layer 32 can be formed. Alternatively, after forming the transparent layer 32 on the entire surface of a predetermined area of the base material 33 without masking, a laser beam in a predetermined wavelength range is irradiated to the non-patterned area to thermally destroy the liquid crystal molecules in the area. It is also possible to provide a polarization function only to the pattern image portion.

In this way, by making the ink forming the transparent layer 32 of the information recording medium out of a transparent ink containing a polarizing material, as in the third and fourth modifications, it is possible to improve the accuracy of the anti-counterfeiting function of the present disclosure and complement it by utilizing the difference in appearance between the image in the hologram layer 31 and the image in the transparent layer 32 due to the relationship between the irradiation angle of visible light and the observation angle. In other words, in addition to the difficulty of duplicating the embedded information under visible light irradiation conditions, only when a specified polarizing film is used can the image in the transparent layer 32 be clearly recognized with almost no influence from the image in the hologram layer 31. This can ensure an additional layer of difficulty in duplicating the embedded information.

Furthermore, the transparent layer 32 may be configured in a mode that includes any or all of the above-described modified examples 3, 4, and 5. For example, the ink forming the transparent layer 32 may be made of a transparent material that includes an infrared absorbing material in addition to a material that emits visible light when excited by infrared rays or ultraviolet rays. Alternatively, the ink forming the transparent layer 32 may be made of an ink of a transparent material that contains a polarizing material in addition to containing an infrared absorbing material. By doing so, it is possible to increase the number of verification methods for determining authenticity, which further contributes to making embedded information more difficult to copy.

(f) Modification 6
In addition to the above, another modification of the information recording medium according to the modifications 3, 4, and 5 of the present disclosure will be described. The information recording medium according to the modifications 3, 4, and 5 improves the verification capability of authenticity determination by mixing an additional authenticity determining material into the ink of the transparent material constituting the transparent layer 32, but such a configuration including the authenticity determining material may be provided in the paper 11 separately from the transparent layer 32 of the first and second embodiments. This modification shows an aspect in which a printed layer including the authenticity determining material according to the modifications 3, 4, and 5 is provided in an area different from the transparent layer 32 in the paper 11.

In this way, by providing a separate printing layer for authenticity verification, which is equipped with the authenticity verification material according to variants 3, 4, and 5, in the area of the paper 11 other than the transparent layer 32 where the code for authenticity verification of the information recording medium is formed as a pattern image, counterfeiting becomes even more difficult, and by providing some kind of relationship between the information on both, the verification accuracy of authenticity verification can be further improved.

5 Reading device 10, 10a Printed matter 11 Paper 21 Illumination light source 22 Viewpoint 22a Viewpoint 22b at position P1 Viewpoint 22c at position P2 Viewpoint 23 at position P3 Cameras 30, 30a, 30b, 30c Information recording body 31 Hologram layer 31a Resin layer 31b Reflective layer 31p, 31p, 31r, 32p Pattern image 32 Transparent layer 33 Base material 34 Adhesive layer 35 Peeling layer 36 Support base material 40 Copy product 41 Paper 43 Ink layer 45 Printed material 50 Control section 51 Image reception section 52 Frequency conversion section 53 Analysis section 54 Code identification section 60 Storage section 62 Code table 65 Reading section 67 Operation section 68 Display section 100 Transfer foil films C1, C2 Pattern images C1a, C2a Foreground section C1b, C2b Background section D0, D1, D2, D0-2, D1- 2, D2-2 Feature points F, F1, F2 Spatial frequency domain G0, G1, G2 Feature points T0, T1, T2 Repetitive shape T10, T11, T12, T10-2, T11-2, T12-2 Circumferential shape T20 , T21, T22 lattice shape

Claims (12)

An information recording medium having a composite image including a first image formed in a hologram layer and a second image formed on the first image,
the second image is printed with ink that reflects different amounts of light depending on an observation angle;
The composite image is recognizable by a reading device as one of the images depending on an observation angle,
the second image is an image that is meaningless to a person at first glance and has regularity in feature points in a spatial frequency domain ;
At a first position where the observation angle is different from an exit angle at the time of regular reflection with respect to an incident angle of an illumination light source, the first image is visible and the second image is not visible;
At a second position where the observation angle is equal to an exit angle at specular reflection with respect to an incident angle of an illumination light source, the first image is not visible and the second image is visible;
An information recording medium, wherein at a third position which is between the first position and the second position, the observation angle is different from the exit angle upon direct reflection relative to the incident angle of the illumination light source but is near the second position, both the first image and the second image are visible. An information recording medium having a composite image including a first image formed in a hologram layer and a second image formed on the first image,
the second image is printed with ink that reflects different amounts of light depending on an observation angle;
the composite image is such that one of the images can be recognized by a reading device depending on an observation angle, and the one of the images includes an image that is meaningless at first glance to a person;
the second image is an image having regularity in feature points in a spatial frequency domain,
the portion of the first image is an image in which at least one or more feature points among feature points in a spatial frequency domain are arranged at a position that disrupts the regularity,
At a first position where the observation angle is different from an exit angle at the time of regular reflection with respect to an incident angle of an illumination light source, the first image is visible and the second image is not visible;
At a second position where the observation angle is equal to an exit angle at specular reflection with respect to an incident angle of an illumination light source, the first image is not visible and the second image is visible;
An information recording medium, wherein at a third position which is between the first position and the second position, the observation angle is different from the exit angle upon direct reflection relative to the incident angle of the illumination light source but is near the second position, both the first image and the second image are visible. An information recording medium having a composite image including a first image formed in a hologram layer and a second image formed on the first image,
the second image is printed with ink that reflects different amounts of light depending on an observation angle;
The composite image is recognizable by a reading device as one of the images depending on an observation angle,
the second image is an image that is meaningless to a person at first glance and has regularity in feature points in a spatial frequency domain ;
the second image is formed of a transparent material to form a transparent layer;
a transparent substrate is disposed between the hologram layer and the transparent layer;
An information recording medium , wherein the difference in refractive index between the transparent layer and the substrate is 0.1 or more . An information recording body comprising a composite image including a first image formed on a hologram layer and a second image formed on the first image,
The second image is printed with ink having a different amount of reflected light depending on the viewing angle,
In the composite image, one image can be recognized by a reading device depending on the viewing angle,
The second image is an image that is meaningless to a person at first glance, and has regularity in feature points in the spatial frequency domain ,
the second image is formed of a transparent material to constitute a transparent layer;
A transparent base material is arranged on the side of the transparent layer opposite to the hologram layer,
The information recording body , wherein the refractive index of the transparent layer has a difference of 0.1 or more with respect to the refractive index of the base material . A release layer is further disposed between the transparent layer and the base material,
The information recording body according to claim 4 , wherein the refractive index of the transparent layer has a difference of 0.1 or more from the refractive index of the release layer. 3. The information recording medium according to claim 2, wherein a first shape represented by feature points in the spatial frequency domain of a portion of the first image and a second shape represented by feature points in the spatial frequency domain of the second image are the same or similar shapes. 7. The information recording medium according to claim 6 , wherein the first shape and the second shape are repeating shapes. 8. The information recording medium according to claim 2, wherein the part of the first image and the second image are images in which feature points in a spatial frequency domain appear at specific positions. . 6. The information recording medium according to claim 3 , wherein the second image is made of ink of the transparent material that is excited by infrared rays or ultraviolet rays and emits visible light. The information recording medium according to any one of claims 3 to 5 , wherein the second image is composed of ink containing an infrared absorbing material. The information recording medium according to any one of claims 3 to 5 , wherein the second image is composed of ink containing a polarizing material. A printed matter comprising the information recording body according to any one of claims 1 to 11 .