JP5842495B2 - Information recording medium - Google Patents

Description

  The present invention relates to an information recording medium to which a forgery prevention technique is applied.

  Generally, forgery prevention technology is applied to securities such as banknotes, gift certificates and checks, and certificates such as passports. Such anti-counterfeiting techniques include, for example, an overt technique that enables visual determination of authenticity and a covert technique that requires a verifier for authenticity determination.

  While the overt technique has the advantage of not requiring a verifier, it is easy to realize that the anti-counterfeiting technique is applied. Therefore, the overt technique is not necessarily effective in preventing forgery.

  Some covert techniques use birefringence. In such a covert technique, for example, a retardation layer including a plurality of regions having different optical axis directions is formed. These regions cannot be distinguished from each other when observed with the naked eye, but constitute a latent image that can be distinguished from each other by observing through a polarizer.

  While this technology has the advantage that it is difficult to realize that anti-counterfeiting technology is applied, it requires a verifier for authenticity determination. Therefore, in the situation where the verifier is not possessed, the authenticity determination cannot be performed.

  Patent Document 1 describes an information recording medium in which a polarizer and an optical element are attached to a flexible support having light transmission properties while being separated from each other. This optical element includes a transparent or light-scattering support, and a polarizer, an alignment film, and a retardation layer sequentially formed thereon. The retardation layer is made of a liquid crystal polymer and includes a plurality of regions having different optical axis directions. When this information recording medium is bent so that the retardation layer is interposed between the polarizers, the latent image recorded on the retardation layer is visualized.

Special table 2001-525080 gazette

The above information recording medium provides the visual effect described above. However, more complicated visual effects are desired to achieve a high anti-counterfeit effect.
An object of the present invention is to enable a complicated visual effect to be realized.

  The first aspect of the present invention is a support layer having a first surface and a second surface which is the back surface thereof, and includes first and second portions having light transparency, The first and second parts are overlapped by folding or bending so that the first surface is inward, and the first and second parts are folded by bending or bending so that the second surface is inward. A support layer capable of overlapping portions, a first linear polarizer provided to face the first portion in a state where the support layer is expanded, and a state in which the support layer is expanded A first reflective layer provided to face the second portion, and the first linear polarizer in a state where the support layer is spread, and the support layer faces the first surface inside. Folding or bending and overlapping the first and second parts, the first linear deviation A first retardation layer provided so as to be positioned between a child and the first reflective layer, and the support layer facing the first reflective layer in a state where the support layer is spread, and the support layer is A second portion is provided so as to be positioned between the first linear polarizer and the first reflective layer in a state where the first and second portions are overlapped with each other folded or bent so that the surface is inward. An information recording medium comprising a retardation layer.

  The second aspect of the present invention is the information recording medium according to the first aspect, wherein the first reflective layer is provided with a relief type diffraction grating or hologram.

  According to a third aspect of the present invention, the support layer is rectangular, and the first and second portions overlap when the support layer is folded so that a crease parallel to the short side is formed. An information recording medium according to the first or second aspect.

  According to a fourth aspect of the present invention, the first retardation layer includes first and second regions having different optical axis directions, and the second retardation layer has third and different optical axis directions. An information recording medium according to any one of the first to third aspects including a fourth area.

  In the fifth aspect of the present invention, the pattern formed by the first or second region is different from the pattern formed by the third region and the pattern formed by the fourth region. This is an information recording medium according to four aspects.

  In a sixth aspect of the present invention, one optical axis of the first and second regions is parallel or orthogonal to the transmission axis of the first linear polarizer, and the first and second The other optical axis of the region is the information recording medium according to the fourth or fifth side surface that is inclined with respect to the transmission axis of the first linear polarizer.

  In the seventh aspect of the present invention, one optical axis of the third and fourth regions is parallel or perpendicular to the transmission axis of the first linear polarizer, and the third and fourth The other optical axis of the region is the information recording medium according to any one of the fourth to sixth side surfaces that are oblique to the transmission axis of the first linear polarizer.

  In an eighth aspect of the present invention, the first linear polarizer and the first retardation layer are at least a part of a first laminated structure supported on the first or second surface at the position of the first portion. The first reflective layer and the second retardation layer constitute at least a part of the second laminated structure supported on the first or second surface at the position of the second portion. An information recording medium according to any one of the first to seventh aspects.

  According to a ninth aspect of the present invention, the first to eighth aspects further include a second linear polarizer facing the second retardation layer with the first reflective layer interposed therebetween with the support layer being spread. An information recording medium according to any one of the aspects.

  The tenth aspect of the present invention further comprises a second linear polarizer facing the second retardation layer with the first reflective layer sandwiched between the support layers, and the first straight line. The polarizer and the first retardation layer constitute at least part of the first laminated structure supported on the first or second surface at the position of the first portion, and the first reflective layer and the first retardation layer The second retardation layer and the second linear polarizer constitute at least a part of the second laminated structure supported by the first or second surface at the position of the second portion. An information recording medium according to any one of the aspects.

  The eleventh aspect of the present invention faces the first retardation layer with the first linear polarizer interposed therebetween, or is interposed between the first linear polarizer and the first retardation layer, The information recording medium according to any one of the first to tenth aspects, further comprising a second reflective layer having optical transparency, wherein the second reflective layer is configured to emit diffracted light.

  According to the present invention, it is possible to realize a complicated visual effect.

  Whether the information recording medium according to the first aspect is optically anisotropic or isotropic when each of the first and second retardation layers is observed with the naked eye with the support layer spread. I do n’t know. However, in this information recording medium, the support layer is folded or bent so that the first retardation layer is interposed between the first linear polarizer and the reflection layer, and in this state, the observation is made with the naked eye from the first portion side. Then, a first image having different brightness is displayed according to an angle formed by the transmission axis of the first linear polarizer and the optical axis of the first retardation layer. Further, in this information recording medium, the support layer is folded or bent so that the second retardation layer is interposed between the first linear polarizer and the reflective layer, and in this state, the first portion side is observed with the naked eye. Then, a second image with different brightness is displayed according to the angle formed by the transmission axis of the first linear polarizer and the optical axis of the second retardation layer. The brightness of the first and second images changes according to the orientation, thickness, refractive index, and the like of the optical axes of the first and second retardation layers, respectively. That is, the brightness of the first and second images can be set independently of each other. Therefore, for example, the brightness of the first and second images can be made different.

  The information recording medium according to the second aspect is the information recording medium described above, wherein a relief type diffraction grating or hologram is provided on the reflective layer. The image displayed by the diffraction grating or hologram makes it difficult to recognize the presence of the second retardation layer.

  An information recording medium according to a third aspect of the present invention is the information recording medium, wherein the support layer is rectangular, and the first and second portions are formed with folds parallel to the short side of the support layer. In this way, it is provided so as to overlap when folded. Such an information recording medium is easy to align for displaying the first and second images.

  In the information recording medium according to the fourth aspect, in the information recording medium, the first retardation layer is provided with first and second regions having different optical axis directions, and the optical axis direction is provided in the second retardation layer. Are provided with third and fourth regions different from each other. That is, latent images are recorded on each of the first and second retardation layers. Such a structure is difficult to manufacture as compared with a retardation layer having the same optical characteristics throughout. In addition, some information such as characters, symbols, patterns, or figures is displayed on each of the first pattern formed by the first or second region and the second pattern formed by the third or fourth region. be able to. Therefore, this information recording medium can achieve a higher forgery prevention effect.

  In the information recording medium according to the fifth aspect, in the information recording medium according to the fourth aspect, the pattern formed by the first or second region is formed by the pattern formed by the third region and the fourth region. Make the pattern different. In this case, the difference between the patterns can be used for confirming the difference between the first and second images.

  The information recording medium according to the sixth aspect is the information recording medium according to the fourth or fifth aspect, wherein one optical axis of the first and second regions is parallel to the transmission axis of the first linear polarizer. Or the other optical axis of the first and second regions is inclined with respect to the transmission axis of the first linear polarizer. Such a structure is advantageous in maximizing the contrast ratio of the first image.

  The information recording medium according to the seventh aspect is the information recording medium according to any one of the fourth to sixth aspects, wherein one optical axis of the third and fourth regions is set to the transmission axis of the first linear polarizer. The optical axes of the third and fourth regions are inclined with respect to the transmission axis of the first linear polarizer. Such a structure is advantageous in maximizing the contrast ratio of the second image, for example, when the structure defined in the third aspect is adopted.

  An information recording medium according to an eighth aspect is the information recording medium according to the first laminated structure, wherein the first linear polarizer and the first retardation layer are supported on the first or second surface at the position of the first portion. The reflection layer and the second retardation layer constitute at least a part of the second laminated structure supported on the first or second surface at the position of the second part. Such an information recording medium is easy to manufacture.

  An information recording medium according to a ninth aspect further comprises a second linear polarizer facing the second retardation layer with the reflective layer sandwiched between the information recording medium and the support layer being expanded. is there. In this information recording medium, when the support layer is folded or bent so that the first retardation layer is interposed between the first and second linear polarizers and the transmitted light is observed in this state, the second linearly polarized light is obtained. A third image whose brightness changes in accordance with the angle formed by the transmission axis of the child and the optical axis of the first retardation layer is displayed. Then, this information recording medium has a structure in which the support layer is folded or bent so that the second retardation layer is interposed between the first and second linear polarizers, and the transmitted light is observed in this state. A fourth image whose brightness changes according to the angle formed by the transmission axis of the linear polarizer and the optical axis of the second retardation layer is displayed.

  The information recording medium according to the tenth aspect is the information recording medium according to any one of the first to seventh aspects, wherein the first linear polarizer is opposed to the second linear polarizer with the support layer being expanded and the reflective layer interposed therebetween. Two linear polarizers are further provided, and the first linear polarizer and the first retardation layer constitute at least a part of the first laminated structure supported on the first or second surface at the position of the first portion. The reflection layer, the second retardation layer, and the second linear polarizer constitute at least a part of the second laminated structure supported on the first or second surface at the position of the second portion. Such an information recording medium is easy to manufacture.

  An information recording medium according to an eleventh aspect is the information recording medium according to any one of the first to tenth aspects, facing the first retardation layer with a first linear polarizer interposed therebetween, or a first straight line. It further includes a second reflective layer that is interposed between the polarizer and the first retardation layer and has optical transparency, and the second reflective layer is configured to emit diffracted light. . The diffracted light emitted from the second reflective layer makes it difficult to recognize the presence of the first retardation layer.

1 is a plan view schematically showing an information recording medium according to one embodiment of the present invention. The top view which looked at the information recording medium shown in FIG. 1 from the back surface side. Sectional drawing along the III-III line of the information recording medium shown in FIG. Sectional drawing along the IV-IV line of the information recording medium shown in FIG. FIG. 2 is a cross-sectional view schematically showing a state where the information recording medium shown in FIG. 1 is bent so that the front surface thereof is inside. FIG. 6 is a plan view schematically showing an image displayed when the information recording medium shown in FIG. 1 is bent as shown in FIG. 5. FIG. 2 is a cross-sectional view schematically showing a state where the information recording medium shown in FIG. 1 is bent so that the back surface is inside. FIG. 8 is a plan view schematically showing an image displayed when the information recording medium shown in FIG. 1 is bent as shown in FIG. 7. Sectional drawing which shows roughly the structure employable in the information recording medium which concerns on one modification. Sectional drawing which shows schematically the structure employable in the information recording medium which concerns on another modification. Furthermore, sectional drawing which shows schematically the structure employable in the information recording medium which concerns on another modification. Furthermore, sectional drawing which shows schematically the structure employable in the information recording medium which concerns on another modification. The top view which shows roughly an example of the image displayed when the information recording medium which employ | adopted the structure shown in FIG. 12 is observed from the surface side. The top view which shows roughly an example of the image displayed when the information recording medium which employ | adopted the structure shown in FIG. 12 is observed from the back side.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In addition, the same referential mark is attached | subjected to the component which exhibits the same or similar function through all drawings, and the overlapping description is abbreviate | omitted.

  FIG. 1 is a plan view schematically showing an information recording medium according to an aspect of the present invention. FIG. 2 is a plan view of the information recording medium shown in FIG. 1 as viewed from the back side. 3 is a cross-sectional view of the information recording medium shown in FIG. 1 taken along line III-III. 4 is a cross-sectional view taken along line IV-IV of the information recording medium shown in FIG.

  1 to 4, an X direction, a Y direction, and a Z direction are a length direction, a width direction, and a thickness direction of the information recording medium, respectively. Here, for the sake of convenience, the surface depicted in FIG. 1 is the front surface and the surface depicted in FIG. 2 is the back surface. However, the surface depicted in FIG. 2 is the front surface, and the surface depicted in FIG. May be.

  The information recording medium 1 shown in FIGS. 1 to 4 is, for example, securities such as banknotes, gift certificates, and checks, or certificates such as a passport. The information recording medium 1 includes a support layer 10, a first retardation layer 210, a first linear polarizer 220, a second retardation layer 310, and a first reflection layer 320.

  The support layer 10 has a first surface S1 and a second surface S2 that is the back surface thereof. The support layer 10 includes first and second portions each having light transparency. The support layer 10 is folded or bent so that the first surface S1 is inward, and the first and second portions are overlapped, and the support layer 10 is bent or bent so that the second surface S2 is inward. It is possible to overlap the first and second parts. Here, the support layer 10 has a rectangular shape, and the first and second portions overlap when the support layer 10 is folded so that a crease parallel to the short side is formed. The support layer 10 may have a shape other than a rectangle.

  The support layer 10 includes a light transmission layer 110 and printing layers 120a and 120b.

  The light transmission layer 110 has a rectangular shape extending in the X direction. The light transmission layer 110 is, for example, a resin film that is transparent to light having any wavelength in the visible range, and typically to light having almost all wavelengths in the visible range. Alternatively, the light transmission layer 110 is a resin film that exhibits light transmission and light scattering properties with respect to light of any wavelength in the visible range, typically light of almost all wavelengths in the visible range. is there.

  As the resin film, for example, an unstretched film produced by extrusion molding or a casting method, or a stretched film obtained by subjecting this to a stretch treatment can be used. As the stretched film, a uniaxially stretched film or a biaxially stretched film may be used. In addition, since a stretched film can have birefringence, it is preferable to use an unstretched film from a viewpoint of making a design easy.

  Examples of the resin film include cellophane, polycarbonate (PC) film, polyethylene (PE) film, polypropylene (PP) film, polyolefin (PO) film, ethylene vinyl alcohol (EVOH) film, polyvinyl alcohol (PVA) film, polychlorinated A vinyl film, a polyethylene naphthalate (PEN) film, a polyethylene terephthalate (PET) film, a nylon film, an acrylic resin film, or a triacetyl cellulose (TAC) film can be used. The resin film may have a single layer structure or a multilayer structure.

  The print layer 120 a is formed on the surface of the light transmission layer 110. The surface on the printed layer 120a side of the support layer 10 is the first surface S1 described above.

  The print layer 120 a partially covers the surface of the light transmission layer 110. Here, the printing layer 120a includes a pair of edges along a side parallel to the Y direction on the surface of the light transmission layer 110, and a central part located between the edges and spaced from each of the edges. Is covered.

  The print layer 120 b is formed on the back surface of the light transmission layer 110. The surface of the support layer 10 on the printed layer 120b side is the above-described second surface S2.

  The print layer 120 b partially covers the back surface of the light transmission layer 110. Here, the printed layer 120b includes a pair of edges along the side parallel to the Y direction on the back surface of the light transmission layer 110, and a central part located between the edges and spaced from each of the edges. Is covered.

  Typically, at least one of the print layers 120a and 120b holds information that can be optically read. For example, information is recorded as a print pattern on at least one of the print layers 120a and 120b.

  The print layers 120a and 120b may not hold information that can be optically read. For example, the print layers 120a and 120b may be used as a base for recording optically readable information by a method other than printing such as handwriting.

  One of the print layers 120a and 120b may be omitted. Alternatively, both the print layers 120a and 120b may be omitted.

  The portion of the light transmission layer 110 where the print layer 120a or 120b is not provided includes the first and second portions described above. Here, each of the first and second portions has a band shape extending in the Y direction, and is arranged in the X direction. Here, the first and second portions are in a line-symmetric relationship with respect to an axis parallel to the Y direction. In this case, the first and second portions overlap when the support layer 10 is folded so that a fold parallel to the short side is formed.

  The first and second portions may have a shape other than the band shape. Further, the first and second portions may be different in at least one of shape and size as long as they overlap at least partially when the support layer 10 is folded or bent at any position. The first and second portions may be arranged at any position as long as the support layer 10 is folded or bent at any position and at least partially overlaps. Further, the first and second portions may be spaced apart from each other or may be adjacent.

  The first linear polarizer 220 is provided so as to face the first portion with the support layer 10 spread. Here, the first linear polarizer 220 is a layer provided on the first surface S1 and at the position of the first portion.

  As the first linear polarizer 220, for example, an absorptive polarizer can be used. As an absorption type polarizer, for example, a polarizer obtained by impregnating a polyvinyl alcohol (PVA) film with iodine or a dichroic dye and stretching the film, or a dichroic dye is oriented on an alignment film. Can be used.

  As the first linear polarizer 220, another polarizer such as a reflective polarizer may be used. For example, a reflective polarizer formed by combining a cholesteric liquid crystal layer and a quarter-wave plate may be used. Alternatively, as the first linear polarizer 220, the birefringence is used at each interface for the reflectance with respect to the first linearly polarized light and the reflectance with respect to the second linearly polarized light in which the vibration direction of the electric field vector is orthogonal. Different multilayer films may be used. Alternatively, the first linear polarizer 220 has a shape extending in the first direction, each having a plurality of lenses or prisms arranged in a direction intersecting the first direction, and a large amount of light incident from the front. You may use the film which designed each lens or prism so that the incident angle of this may become a Brewster angle or more. Alternatively, as the first linear polarizer 220, a birefringent diffractive polarizer in which a region made of a material having birefringence and a region made of an optically isotropic material are arranged in a stripe shape. May be used. Alternatively, a diffractive polarizer including a diffractive structure with deep grooves may be used. In addition, any element that can obtain linearly polarized light as transmitted light can be used as the first linear polarizer 220.

  Here, as an example, it is assumed that the first linear polarizer 220 is an absorptive polarizer having a transmission axis parallel to the Y direction.

  The first retardation layer 210 faces the first linear polarizer 220 in a state in which the support layer 10 is spread, and the first and second layers are bent or bent so that the first surface S1 is inside. It is provided so as to be positioned between the first linear polarizer 220 and the first reflective layer 320 in a state where the two portions are overlapped. Here, the first retardation layer 210 faces the first portion with the first linear polarizer 220 interposed therebetween.

  The first retardation layer 210 includes a region having birefringence. The first retardation layer 210 may have a uniform optical characteristic over the entirety thereof, and may include a plurality of regions having different optical characteristics. In the latter case, the first retardation layer 210 may include a plurality of regions having different optical axis directions, and may include a plurality of regions having different refractive index anisotropy.

  For example, the first retardation layer 210 may include two or more regions each acting as a uniaxial crystal having an optical axis substantially perpendicular to the Z direction. Moreover, the phase difference which each area | region produces | generates between the linearly polarized light with the vibration direction of an electric field vector parallel to the optical axis, and perpendicular | vertical polarized light is arbitrary. For example, each region can serve as a quarter-wave plate or a half-wave plate for light of any wavelength within the visible range.

  Here, as an example, the first retardation layer 210 includes a first region 210 a whose slow axis is parallel or perpendicular to the transmission axis of the first linear polarizer 220, and a slow axis that is the first linear polarizer. And a second region 210b having an angle of + 45 ° or −45 ° with respect to 220 transmission axes. In addition, here, the second region 210b serves as a quarter-wave plate for light of any wavelength in the visible range.

  For the first retardation layer 210, a material having birefringence, for example, a liquid crystal material can be used. In this case, for example, the first retardation layer 210 is prepared with a base subjected to alignment treatment such as rubbing treatment and photo-alignment treatment corresponding to the slow axis of the regions 210a and 210b, and a liquid crystal material is applied thereon. It can be obtained by curing.

  When using the rubbing treatment, first, a coating film made of a solution containing a polymer such as polyimide and PVA is formed. Next, the coating film is dried, and the surface of the coating film is rubbed with a rubbing cloth. When a liquid crystal material is applied on the alignment film thus obtained, the liquid crystal molecules are aligned in the rubbing direction.

  Here, since the regions 210a and 210b having different slow axis directions are formed, the rubbing process is performed twice as described below. First, a coating film made of a polymer is formed, and a part of the surface is covered with a mask. In this state, a rubbing process is performed on the surface of the coating film that is not covered with a mask. Next, the mask is removed from the coating film, the rubbing-treated area on the surface of the coating film is covered with a mask, and the other areas are subjected to rubbing treatment. After removing the mask, a liquid crystal material is applied on the alignment film thus obtained, and the coating film is cured. If the rubbing directions are made different between the first rubbing process and the second rubbing process, regions 210a and 210b having different slow axis directions are obtained.

  In the photo-alignment treatment, for example, photoisomerization of an azobenzene derivative, photodimerization or photocrosslinking of a derivative such as cinnamic acid ester, coumarin, chalcone and benzophenone, or photolysis of polyimide or the like is used. Specifically, first, a coating film containing the photosensitive material is formed. Then, this coating film is irradiated with linearly polarized light or irradiated with natural light from an oblique direction. This induces an anisotropic rearrangement or chemical reaction of the molecules in the coating. When a liquid crystal material is applied on the alignment film thus obtained, the liquid crystal molecules are aligned corresponding to the anisotropic arrangement of the molecules in the alignment film.

  Here, since the regions 210a and 210b having different slow axis directions are formed, the photo-alignment process is performed as described below. First, a coating film containing a photosensitive material is formed, and a part thereof is exposed to linearly polarized light through a photomask. Next, the other part of the coating film is exposed to linearly polarized light through a photomask. Thereafter, a liquid crystal material is applied on the alignment film thus obtained, and the coating film is cured. If the vibration direction of the electric field vector of linearly polarized light is made different between the first exposure and the second exposure, regions 210a and 210b having different slow axis directions can be obtained.

  Alternatively, first, a coating film containing a photosensitive material is formed, and a part thereof is exposed with natural light from an oblique direction through a photomask. Next, the other part of the coating film is exposed with natural light from an oblique direction through a photomask. Thereafter, a liquid crystal material is applied on the alignment film thus obtained, and the coating film is cured. If the natural light irradiation direction is made different between the first exposure and the second exposure, regions 210a and 210b having different directions of the slow axis are obtained.

  In any of the methods of irradiating linearly polarized light and natural light, the first exposure may be performed on the entire coating film.

  For the application performed to form the alignment film and the liquid crystal layer, for example, a gravure coating method or a micro gravure coating method can be used.

  As the liquid crystal material, for example, a mixture containing a main chain monomer containing a reactive functional group such as an acrylic group at both ends of a mesogenic group and a photopolymerization initiator, a polymerizable functional group contained at one end of the mesogenic group Uses a mixture containing a side chain monomer and a photopolymerization initiator, or a mixture containing a side chain monomer containing a reactive functional group at one end of a mesogenic group, a reactive polymer, and a photopolymerization initiator. can do. When such a liquid crystal material is irradiated with, for example, an electron beam or ultraviolet light, a side chain type or main chain type polymer liquid crystal is obtained. In addition, if the coating film made of these liquid crystal materials is heat-treated at a temperature slightly lower than the phase transition point (NI point) between the nematic phase and the isotropic phase before irradiation with electron beams or ultraviolet rays, the orientation of mesogenic groups is promoted. Can be done.

  The first reflective layer 320 is provided so as to face the second portion described above in a state where the support layer 10 is spread. Here, the first reflective layer 320 is a layer provided on the second surface S2 and at the position of the second portion.

  As the first reflective layer 320, for example, a metal material layer made of a single metal or an alloy can be used. As the single metal or alloy, for example, Al, Sn, Cr, Ni, Cu, Au, Ag, or an alloy containing one or more of them can be used. The first reflective layer 320 may have a single layer structure or a multilayer structure. When using a metal material layer, the 1st reflective layer 320 may have a light transmittance, and may be light-shielding.

  As the first reflective layer 320, a transparent layer that exhibits a relatively high transmittance for light propagating in the Z direction and a relatively high reflectivity for light propagating obliquely to the Z direction is used. It is also possible to do. Such a transparent layer may have a single layer structure or a multilayer structure formed by laminating layers having different refractive indexes.

As the material of the transparent layer or the layer it contains, for example, ceramics or polymers can be used. Examples of ceramics include Fe ₂ O ₃ , TiO ₂ , CdS, CeO ₂ , ZnS, PbCl ₂ , CdO, WO ₃ , SiO, Si ₂ O ₃ , In ₂ O ₃ , PbO, Ta ₂ O ₃ , ZnO, ZrO ₂ , MgO, SiO ₂ , MgF ₂ , CeF ₃ , CaF ₂ , AlF ₃ , Al ₂ O ₃ or GaO can be used. As the polymer, for example, polyethylene, polypropylene, polytetrafluoroethylene, polymethyl methacrylate, or polystyrene can be used.

  When the above transparent layer is used as the first reflective layer 320, a design in which one or more lights having wavelengths in the visible range are repeatedly reflected and interfered may be employed for the transparent layer. When this design is adopted, the first reflective layer 320 can emit interference light. The interference color displayed by the first reflective layer 320 makes it difficult to recognize the presence of the second retardation layer 310.

  The first reflective layer 320 can be formed by, for example, a vapor deposition method such as a vacuum evaporation method, a sputtering method, or a chemical vapor deposition (CVD) method. The first reflective layer 320 may be formed by printing an ink having a light reflecting effect when high accuracy is not required for the thickness.

  The first reflective layer 320 can be provided with a relief type diffraction grating or hologram. If a relief type diffraction grating or hologram is provided on the first reflective layer 320, the presence of the second retardation layer 310 is difficult to be realized.

  The first reflective layer 320 provided with the relief type diffraction grating or hologram is formed by the following method, for example. First, a diffraction structure forming layer (not shown) having a relief structure as a diffraction grating or hologram is formed on the surface by using transfer using a mold. Next, the first reflective layer 320 is formed on the diffractive structure forming layer by the method described above. When a printing method is used to form the first reflective layer 320, the relief structure is transferred to the surface of the first reflective layer 320 that is in contact with the diffractive structure forming layer. In addition, when the vapor deposition method is used for forming the first reflective layer 320, the relief structure described above is formed on the opposite surface of the first reflective layer 320 in addition to the surface in contact with the diffractive structure forming layer. Is transcribed. In this way, the first reflective layer 320 provided with the relief type diffraction grating or hologram is obtained.

  As the material for the diffractive structure forming layer, it is preferable to use a material that has good moldability by heat and the like, is less likely to cause press unevenness, and provides a bright reproduced image. For example, thermoplastic resins such as acrylic resins, epoxy resins, cellulose resins, and vinyl resins; urethane resins, melamine resins, and phenol resins that are crosslinked by adding polyisocyanate as a crosslinking agent to acrylic polyols or polyester polyols having reactive hydroxyl groups Or a thermosetting resin such as epoxy (meth) acrylic or urethane (meth) acrylate, or other ultraviolet or electron beam curable resin can be used.

  Here, as an example, it is assumed that the first reflective layer 320 is a light-shielding metal material layer not provided with a relief type diffraction grating or hologram.

  The second retardation layer 310 faces the first reflective layer 320 in a state in which the support layer 10 is spread, and the support layer 10 is folded or bent so that the second surface S2 is on the first and second layers. It is provided so as to be positioned between the first linear polarizer 220 and the first reflective layer 320 in a state where the portions are overlapped. Here, the second retardation layer 310 faces the second portion with the first reflective layer 320 interposed therebetween.

  The second retardation layer 310 includes a region having birefringence. The second retardation layer 310 may have a uniform optical characteristic over the entirety thereof, and may include a plurality of regions having different optical characteristics. In the latter case, the second retardation layer 310 may include a plurality of regions having different optical axis directions, or may include a plurality of regions having different refractive index anisotropy.

  For example, the second retardation layer 310 may include two or more regions each acting as a uniaxial crystal having an optical axis substantially perpendicular to the Z direction. Moreover, the phase difference which each area | region produces | generates between the linearly polarized light with the vibration direction of an electric field vector parallel to the optical axis, and perpendicular | vertical polarized light is arbitrary. For example, each region can serve as a quarter-wave plate or a half-wave plate for light of any wavelength within the visible range.

  Here, as an example, the second retardation layer 310 has a slow axis when the support layer 10 is folded or bent so that the second surface S2 is inside and the first and second portions are overlapped. Is in parallel or perpendicular to the transmission axis of the first linear polarizer 220 and the slow axis forms an angle of + 45 ° or −45 ° with respect to the transmission axis of the first linear polarizer 220. The fourth region 310b is included. In addition, here, the fourth region 310b serves as a quarter-wave plate for light of any wavelength within the visible range.

  For the second retardation layer 310, a material having birefringence, for example, a liquid crystal material can be used. In this case, the second retardation layer 310 can be obtained by the same method as described above for the first retardation layer 210, for example.

  In the information recording medium 1, the first laminated structure 20 including the first retardation layer 210 and the first linear polarizer 220 is provided on the first surface S 1 of the support layer 10, and the second layer of the support layer 10 is provided. A second stacked structure 30 including the second retardation layer 310 and the first reflective layer 320 is provided on the surface S2. Such a structure is obtained, for example, by attaching the laminated structures 20 and 30 to the support layer 10.

  Reference numerals 20a and 20b represent portions corresponding to the regions 210a and 210b in the first stacked structure 20, respectively. Reference numerals 30a and 30b represent portions of the second stacked structure 30 that correspond to the regions 310a and 310b, respectively.

  Next, an image displayed by the information recording medium 1 will be described. First, an image displayed in a state where the information recording medium 1 is spread will be described with reference to FIGS.

  When the information recording medium 1 is expanded as shown in FIGS. 1 and 2, the portion corresponding to the first laminated structure 20 appears transparent. In this state, the portion corresponding to the second laminated structure 30 of the information recording medium 1 looks like a specular reflection layer.

  Next, an image displayed on the information recording medium 1 in a state where the first surface S1 is bent will be described with reference to FIGS. 5 and 6. FIG.

  FIG. 5 is a cross-sectional view schematically showing a state in which the information recording medium shown in FIG. 1 is bent so that the front surface is inward. FIG. 6 is a plan view schematically showing an image displayed when the information recording medium shown in FIG. 1 is bent as shown in FIG.

  FIG. 5 illustrates a state in which the information recording medium 1 is bent so that the first surface S1 is inside and the first and second portions are overlapped. In FIG. 5, LS represents a light source, and OB represents an observer.

  When the information recording medium 1 shown in FIG. 5 is illuminated with natural light such as white light from the first laminated structure 20 side and the reflected light is observed, the information recording medium 1 is positioned at a position corresponding to the first laminated structure 20 as shown in FIG. The image I1 shown in FIG. The image I1 has a brightness distribution corresponding to the areas 210a and 210b. Here, the image I1 includes a black background and a silver-white foreground having a star shape.

  When the information recording medium 1 shown in FIG. 5 is illuminated with natural light such as white light from the second laminated structure 30 side and the reflected light is observed, the portion corresponding to the second laminated structure 30 of the information recording medium 1 is: Like the case where the information recording medium 1 is spread, it looks like a specular reflection layer.

  Next, an image displayed on the information recording medium 1 in a state where the second surface S2 is bent will be described with reference to FIGS. 7 and 8. FIG.

  FIG. 7 is a cross-sectional view schematically showing a state in which the information recording medium shown in FIG. 1 is bent so that the back surface is inside. FIG. 8 is a plan view schematically showing an image displayed when the information recording medium shown in FIG. 1 is folded as shown in FIG.

  FIG. 7 illustrates a state in which the information recording medium 1 is bent so that the second surface S2 is inside and the first and second portions are overlapped. In FIG. 7, LS represents a light source, and OB represents an observer.

  When the information recording medium 1 shown in FIG. 7 is illuminated with natural light such as white light from the first laminated structure 20 side and the reflected light is observed, the information recording medium 1 is positioned at a position corresponding to the first laminated structure 20 as shown in FIG. An image I2 shown in FIG. The image I2 has a brightness distribution corresponding to the areas 310a and 310b. Here, the image I2 includes a black background and a silver-white foreground having a circular shape.

  When the information recording medium 1 shown in FIG. 7 is illuminated with natural light such as white light from the second laminated structure 30 side and the reflected light is observed, the portion corresponding to the second laminated structure 30 of the information recording medium 1 is: Like the case where the information recording medium 1 is spread, it looks like a specular reflection layer.

  As described above, when the information recording medium 1 is bent and observed under specific conditions, the latent image recorded in the retardation layer 210 or 310 is visualized. Different latent images are visualized when the information recording medium 1 is folded so that the first surface S1 is inside and when the information recording medium 1 is folded so that the second surface S2 is inside. Can do. That is, when the above-described structure is employed, a complicated visual effect can be realized.

  Moreover, it is not easy for those who try to counterfeit to reproduce this complicated visual effect. Therefore, the above-described structure achieves a high anti-counterfeit effect.

  Further, no verification tool is required to confirm this complicated visual effect. Therefore, authenticity determination can be performed at various stages in which the information recording medium 1 is distributed.

The information recording medium 1 can be variously modified.
For example, as the support layer 10, a plurality of windows are provided in an opaque or translucent layer such as paper instead of the light transmitting layer 110, and the light transmitting layer is supported by the opaque or translucent layer at the positions of these windows. You may use the thing containing a structure.

  Various modifications can be made to the arrangement of the first retardation layer 210, the first linear polarizer 220, the second retardation layer 310, and the first reflective layer 320.

  FIG. 9 is a cross-sectional view schematically showing a structure that can be employed in an information recording medium according to a modification. FIG. 10 is a cross-sectional view schematically showing a structure that can be employed in an information recording medium according to another modification.

  In the structure shown in FIG. 9, the first laminated structure 20 is provided on the second surface S2. In this structure, the first retardation layer 210 is interposed between the light transmission layer 110 and the first linear polarizer 220. The information recording medium 1 described with reference to FIGS. 1 to 4 may employ the structure shown in FIG. 9 instead of the structure shown in FIG.

  In the structure shown in FIG. 10, the second laminated structure 30 is provided on the first surface S1. In this structure, the second retardation layer 310 is interposed between the light transmission layer 110 and the first reflection layer 320. The information recording medium 1 described with reference to FIGS. 1 to 4 may employ the structure shown in FIG. 10 instead of the structure shown in FIG.

  Further, the information recording medium 1 described with reference to FIGS. 1 to 4 employs the structure shown in FIG. 9 instead of the structure shown in FIG. 3, and instead of the structure shown in FIG. The structure shown may be employed.

  Instead of providing the first stacked structure 20 on the first surface S1 or the second surface S2, the first retardation layer 210 and the first linear polarizer 220 are provided on the first surface S1 and the second surface S2, respectively. May be. Similarly, instead of providing the second laminated structure 30 on the first surface S1 or the second surface S2, the first reflective layer 320 and the second retardation layer 310 are respectively formed on the first surface S1 and the second surface S2. May be provided.

  FIG. 11 is a cross-sectional view schematically showing a structure that can be employed in an information recording medium according to still another modification.

  In the structure shown in FIG. 11, the second stacked structure 30 further includes a second linear polarizer 330. The second linear polarizer 330 faces the second retardation layer with the support layer 10 spread and the first reflective layer 320 interposed therebetween. As the 2nd linear polarizer 330, what was mentioned above about the 1st linear polarizer 220 can be used, for example.

  The direction of the transmission axis of the second linear polarizer 330 is arbitrary. For example, in a state where the information recording medium 1 is bent so that the first and second portions overlap, the transmission axis of the first linear polarizer 220 and the transmission axis of the second linear polarizer 330 may be parallel. , May be orthogonal.

  In the information recording medium 1 adopting this structure, when the support layer 10 is folded or bent so that the first retardation layer 210 is interposed between the linear polarizers 220 and 330 and the transmitted light is observed in this state, A third image whose brightness changes in accordance with the angle formed by the transmission axis of the two linear polarizers 330 and the optical axis of the first retardation layer 210 is displayed. The information recording medium 1 is formed by bending or bending the support layer 10 so that the second retardation layer 310 is interposed between the linear polarizers 220 and 330 and observing the transmitted light in this state. A fourth image whose brightness changes according to an angle formed by the transmission axis of the polarizer 220 and the optical axis of the second retardation layer 310 is displayed.

  That is, when this structure is employed, display using transmitted light is possible in addition to display using reflected light. Therefore, when this structure is adopted, a more complicated visual effect can be realized, and therefore a higher forgery prevention effect can be achieved.

  This structure can be applied to any of the information recording medium 1 described with reference to FIGS. 1 to 4 and the information recording medium according to the modification described with reference to FIGS. 9 and 10. . That is, in the information recording medium 1 described with reference to FIGS. 1 to 4 and the information recording medium according to the modification described with reference to FIGS. 9 and 10, FIG. The structure described with reference may be adopted.

  FIG. 12 is a cross-sectional view schematically showing a structure that can be employed in an information recording medium according to still another modification.

  In the structure shown in FIG. 12, the first stacked structure 20 further includes a second reflective layer 230. The second reflective layer 230 faces the first retardation layer 210 with the first linear polarizer 220 interposed therebetween. The second reflective layer 230 may be interposed between the first linear polarizer 220 and the first retardation layer 210.

  The second reflective layer 230 is a transparent layer having a single layer structure or a multilayer structure. As this transparent layer, what was illustrated about the 1st reflective layer 320 can be used, for example.

  The second reflective layer 230 employs a design in which one or more lights having wavelengths in the visible range are repeatedly reflected and interfered. Alternatively, the second reflective layer 230 is provided with a relief type diffraction grating or hologram. Alternatively, the second reflective layer 230 employs a design in which one or more lights whose wavelengths are in the visible range are repeatedly reflected and interfered, and a relief type diffraction grating or hologram is provided. Here, as an example, the second reflective layer 230 is provided with a relief type diffraction grating.

  FIG. 13 is a plan view schematically showing an example of an image displayed when the information recording medium employing the structure shown in FIG. 12 is observed from the front side. FIG. 14 is a plan view schematically showing an example of an image displayed when the information recording medium employing the structure shown in FIG. 12 is observed from the back side.

  In the example shown in FIGS. 13 and 14, relief type diffraction gratings are provided in both the first reflective layer 320 and the second reflective layer 230. Specifically, a diffraction grating whose length direction is parallel to the X direction is provided in a part of the first reflective layer 320, and the length of the groove is provided in the other part of the first reflective layer 320. A diffraction grating whose direction is parallel to the Y direction is provided. Further, a diffraction grating whose groove length direction is parallel to the X direction is provided in a part of the second reflective layer 230, and the groove length direction is Y in the other part of the second reflective layer 230. A diffraction grating parallel to the direction is provided.

  When such a structure is adopted, for example, when the information recording medium 1 is illuminated from a direction perpendicular to the X direction and inclined with respect to the Z direction, and the information recording medium 1 is observed from the front, the length of the groove A diffraction grating whose direction is parallel to the X direction emits diffracted light toward the observer, and a diffraction grating whose groove length direction is parallel to the Y direction does not emit diffracted light toward the observer. Therefore, the information recording medium 1 displays the images shown in FIGS. 13 and 14, for example.

  Thus, if the structure which inject | emits a diffracted light to the 2nd reflective layer 230 is employ | adopted, the presence of the 1st phase difference layer 210 can be made hard to understand.

  Examples of the present invention will be described below.

  The information recording medium 1 described with reference to FIGS. 1 to 4 was manufactured by the following method. However, in this example, the printing layers 120a and 120b are omitted.

  First, a rectangular unstretched triacetyl cellulose (TAC) film was prepared as the support layer 10, and the first linear polarizer 220 was attached to the first surface S 1 of the support layer 10. As the first linear polarizer 220, a belt-like film obtained by impregnating iodine in a PVA film and uniaxially stretching in the length direction was used. The first linear polarizer 220 was pasted so that its length direction was parallel to the Y direction.

  Next, a solution obtained by dissolving a resin as a material for the alignment film in a solvent was applied onto the first linear polarizer 220 by a microgravure method. After drying, a mask having a star shape was placed on the coating film, and in this state, the coating film was rubbed. Here, the rubbing direction is a direction that forms an angle of 45 ° with respect to the Y direction. After removing the star-shaped mask from the coating film, a mask having a star-shaped opening was placed on the coating film, and in this state, the coating film was rubbed. Here, the rubbing direction was parallel to the Y direction.

  Next, a liquid crystal material was applied on the alignment film obtained as described above by a microgravure method. As a liquid crystal material, UV curable liquid crystal UCL-008 manufactured by DIC Corporation was used. The first retardation layer 210 was obtained by curing this coating film by irradiation with ultraviolet rays in an oxygen atmosphere. The first retardation layer 210 was formed in a thickness such that the retardation for light having a wavelength λ of 550 nm was λ / 4 in each of the regions 210a and 210b.

Next, a transfer foil including a base material and a transfer material layer was prepared.
Specifically, first, a PET film was prepared as a base material. On this base material, a solution obtained by dissolving a resin as a material for the alignment film in a solvent was applied by a microgravure method. After drying, a mask having a circular shape was placed on the coating film, and in this state, the coating film was rubbed. After the mask having a circular shape was removed from the coating film, a mask with a circular opening was placed on the coating film, and in this state, the coating film was rubbed. Here, these rubbing was performed so that their rubbing directions form an angle of 45 °.

  Next, a liquid crystal material was applied on the alignment film obtained as described above by a microgravure method. As a liquid crystal material, UV curable liquid crystal UCL-008 manufactured by DIC Corporation was used. This coating film was cured by ultraviolet irradiation in an oxygen atmosphere to obtain a retardation layer. This retardation layer has a retardation of λ / 4 for light having a wavelength λ of 550 nm in each of a region where a circular mask is arranged and a region where a mask provided with a circular opening is placed. The thickness was such that

  Next, a thermoplastic resin layer having a thickness of 0.8 μm was formed on the retardation layer by gravure printing. Next, the relief structure was transferred to the surface of the thermoplastic resin layer by a roll embossing method. In this roll embossing method, a nickel mold provided with a pattern corresponding to the grooves of the diffraction grating was used, and the mold was heated to 165 ° C.

  Subsequently, on the diffractive structure forming layer obtained in this way, aluminum was deposited to a thickness of 80 nm by a vacuum evaporation method to obtain a reflective layer.

  Further, an adhesive made of a thermoplastic resin was applied on the reflective layer by a microgravure method to obtain an adhesive layer having a thickness of 2 μm. As the adhesive, a resin containing a copolymer of vinyl chloride and vinyl acetate was used.

  As described above, the transfer material layer was formed by sequentially laminating the retardation layer, the diffraction structure forming layer, the reflective layer, and the adhesive layer made of the thermoplastic resin from the base material side.

  Next, a part of the transfer material layer was thermally transferred from the transfer foil base material onto the second surface S2 of the support layer 10 using a roll transfer machine. Specifically, the transfer foil and the previous support layer 10 are arranged so that the adhesive layer of the transfer foil faces the second surface S2 of the support layer 10, and the transfer foil is heated while applying heat in this state. It pressed against 2nd surface S2, and the base material was removed from the support body layer 10 after that. As a result, the portion of the transfer material layer to which heat and pressure were applied was transferred from the substrate to the support layer 10. This transfer was performed so that the rubbing direction in the region where the circular mask was arranged in the retardation layer included in the transfer material layer was parallel to the Y direction. By this transfer, the reflective layer 320 and the second retardation layer 310 were provided on the second surface S2 of the support layer 10.

  The information recording medium 1 obtained in this manner corresponds to the areas 210a and 210b, although the diffracted light from the reflective layer 320 can be perceived when the first surface S1 side is observed with the naked eye in the spread state. Parts 20a and 20b could not be distinguished from each other. Similarly, in the information recording medium 1, when the second surface S2 side is observed with the naked eye in the spread state, the diffracted light from the reflective layer 320 can be perceived, but the portions 20a and 210b corresponding to the regions 210a and 210b, respectively. 20b could not be distinguished from each other.

  Next, as shown in FIG. 5, the information recording medium 1 was bent so that the first surface S1 was inside, and observed with the naked eye from the first laminated structure 20 side. As a result, the information recording medium 1 displayed the first image I1 shown in FIG. 6 at the position of the first laminated structure 20.

  Subsequently, as shown in FIG. 7, the information recording medium 1 was bent so that the second surface S2 was inside, and observed with the naked eye from the first laminated structure 20 side. As a result, the information recording medium 1 displayed the second image I2 shown in FIG. 8 at the position of the first laminated structure 20.

  DESCRIPTION OF SYMBOLS 1 ... Information recording medium, 10 ... Support layer, 110 ... Light transmission layer, 120a ... Print layer, 120b ... Print layer, 210 ... 1st phase difference layer, 210a ... 1st area | region, 210b ... 2nd area | region, 220 ... First linear polarizer, 230 ... second reflective layer, 310 ... second retardation layer, 320 ... first reflective layer, I1 ... first image, I2 ... second image, LS ... light source, OB ... observer, S1 ... 1st surface, S2 ... 2nd surface.

Claims (10)

A support layer having a first surface and a second surface that is the back surface of the support layer. The support layer includes first and second portions having optical transparency, and the first surface is on the inside. It is possible to overlap the first and second parts by folding or bending the first and second parts, and to overlap the first and second parts by folding or bending the second surface to be inside. A support layer,
  A first linear polarizer provided on the first surface of the support layer and at the position of the first portion;
  A first retardation layer provided on the first linear polarizer;
  A first reflective layer on the second surface of the support layer and provided at a position of the second portion;
  A second retardation layer provided on the first reflective layer;
An information recording medium comprising:
  The first retardation layer includes first and second regions having different optical axis directions, and the second retardation layer includes third and fourth regions having different optical axis directions. Medium. The information recording medium according to claim 1, further comprising a second linear polarizer between the second portion of the support layer and the first reflective layer. A second reflective layer is further provided between the first portion of the support layer and the first linear polarizer, or between the first linear polarizer and the first retardation layer. Item 3. The information recording medium according to Item 1 or 2. A support layer having a first surface and a second surface that is the back surface of the support layer. The support layer includes first and second portions having optical transparency, and the first surface is on the inside. It is possible to overlap the first and second parts by folding or bending the first and second parts, and to overlap the first and second parts by folding or bending the second surface to be inside. A support layer,
  A first retardation layer provided on the second surface of the support layer and at the position of the first portion;
  A first linear polarizer provided on the first retardation layer;
  A second retardation layer provided on the first surface of the support layer and at the position of the second portion;
  A first reflective layer provided on the second retardation layer;
An information recording medium comprising:
  The first retardation layer includes first and second regions having different optical axis directions, and the second retardation layer includes third and fourth regions having different optical axis directions. Medium. 5. The information recording medium according to claim 1, wherein a relief type diffraction grating or a hologram is provided on the first reflective layer. The said support body layer is rectangular shape, The said 1st and 2nd part overlaps when the said support body layer is folded so that a crease | fold parallel to the short side may be formed . The information recording medium described in 1. Pattern the first or the second region is formed, in any one of claims 1 to 6, which is different from the pattern the pattern and the fourth region and the third region is formed is formed The information recording medium described. One optical axis of the first and second regions is parallel or perpendicular to the transmission axis of the first linear polarizer, and the other optical axis of the first and second regions is The information recording medium according to claim 1 , wherein the information recording medium is inclined with respect to a transmission axis of the first linear polarizer. One optical axis of the third and fourth regions is parallel or orthogonal to the transmission axis of the first linear polarizer, and the other optical axis of the third and fourth regions is The information recording medium according to claim 1 , wherein the information recording medium is inclined with respect to a transmission axis of the first linear polarizer. The first linear polarizer and the first retardation layer constitute at least a part of a first laminated structure supported on the first or second surface at the position of the first portion, and the first reflection 10. The layer according to claim 1, wherein the layer and the second retardation layer constitute at least a part of a second laminated structure supported by the first or second surface at the position of the second portion . The information recording medium described in 1.

Images