JP2014046667A - Information display medium, and authenticity determination method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an information display medium with counterfeit prevention effect, and to provide an authenticity determination method thereof.SOLUTION: An information display medium has a first micropattern area for displaying an enlarged image by the moire effect generated by superposition with a lens array on a portion of a surface of a substrate, and has a second micropattern area for displaying the enlarged image by the moire effect generated by the superposition with the lens array on a portion of a back side of the substrate.

Description

  The present invention relates to an information display medium using a forgery prevention capability provided with a lens array, and an authenticity determination method thereof.

  In order to prevent forgery, a display body on which a latent image is recorded, or a display body that causes a color change depending on an observation angle or the like may be used. The latent image can be formed using, for example, a line moire. In addition, a color change according to an observation angle or the like can be generated using a diffraction grating or a hologram.

  Such a display body with a color change caused by a hologram cannot be reproduced by a normal printing technique, and is therefore effective in preventing counterfeiting of information display media such as banknotes and securities to which the display body is attached and various articles (patents) Reference 1).

  However, as this technology has been used in many information display media and other goods that require anti-counterfeiting measures, this technology has become widely recognized, and along with this, the occurrence of counterfeit products tends to increase. Yes, further progress is desired.

  In addition, a display body using a lens array is known as a display body that changes an image according to an observation angle or the like, and a microlens array and a fine print pattern are bonded together with high accuracy, and an enlargement caused by a moire effect. It is possible to display an image. In this display body, display with a stereoscopic effect and a sense of depth is possible, for example, an enlarged image appears to move as the observation angle changes (Patent Document 2).

  However, as a result of the use of such technology not only in information display media and other articles that require anti-counterfeiting measures, but also in toys and stationery, further progress is desired as anti-counterfeiting applications. .

JP-A-10-123919 Special table 2009-536885 gazette

  The objective of this invention is providing the information display medium provided with the high forgery prevention effect, and its authenticity determination method.

As a means for solving the above problems, the invention according to claim 1 is an information display medium in which a planar substrate is provided with a light-transmitting lens array structure that can be observed from the front and back,
A first micro pattern region that displays an enlarged image due to the moire effect generated by superimposing with the lens array on a part of the surface of the substrate;
An information display medium having a second micro pattern region for displaying an enlarged image by a moire effect generated by superimposing with the lens array on a part of the back surface of the substrate.

  According to a second aspect of the present invention, in the information display according to the first aspect, the planar base material has an opening window, and the lens array is provided in the opening window. It is a medium.

  The invention according to claim 3 is characterized in that at least a part of the planar substrate has a light-transmitting region, and the lens array is provided in the light-transmitting region. The information display medium according to claim 1.

  According to a fourth aspect of the present invention, the lens array is a microlens array having a cross-sectional structure composed of a circle or a part of a circle, and the lenses are arranged in a square matrix or a triangular matrix. The information display medium according to any one of claims 1 to 3.

  The invention according to claim 5 is the information display medium according to any one of claims 1 to 3, wherein the lens array is a prism lens array having a triangular cross section. .

  The invention according to claim 6 is the information according to any one of claims 1 to 5, wherein a top portion of the structure of the lens array does not protrude from a surface of the planar substrate. It is a display medium.

  In the invention according to claim 7, any one of the first micro pattern and the second micro pattern, or the first micro pattern and the second micro pattern is formed of printing ink. It is an information display medium as described in any one of Claims 1-6 characterized by the above-mentioned.

  In the invention according to claim 8, any one of the first micropattern and the second micropattern, or the first micropattern and the second micropattern is any one of diffraction, light scattering, and light absorption. The information display medium according to any one of claims 1 to 7, wherein the information display medium is formed from a fine structure having the following functions.

The invention according to claim 9 is an enlarged image by a moire effect generated by superimposing the first micro pattern and the lens array;
9. The information display medium according to claim 1, wherein the same information is displayed by an enlarged image by a moire effect generated by superimposing the second micropattern and the lens array. is there.

The invention according to claim 10 is an enlarged image by a moire effect generated by superimposing the first micro pattern and the lens array;
9. The information display medium according to claim 1, wherein the enlarged image due to the moire effect generated by superimposing the second micropattern and the lens array displays different information. .

The invention according to claim 11 is an enlarged image by a moire effect generated when the information display medium is bent and the lens array and the first micro pattern are overlapped with each other.
The information display medium according to any one of claims 1 to 10, wherein the information display medium is bent by the opposite side and an enlarged image by a moire effect generated when the lens array and the second micropattern are overlapped. An authenticity determination method characterized by determining authenticity.

  With the configuration of the present invention, according to the first invention, the information display medium has a light-transmitting lens array structure that can be observed from the front and back on a part of the planar substrate, and further information A part of one main surface of the base material of the display medium has a first micro pattern region in which an enlarged image can be displayed by a moire effect generated by superposition with the lens array.

  Further, on the surface opposite to the main surface on which the first micropattern region is formed, that is, the back surface, a second micropattern region capable of displaying an enlarged image by a moire effect caused by superimposition with the lens array is further provided. Have. The information display medium is folded by, for example, overlapping the lens array and the first micro pattern, and the authenticity of the information display medium is determined based on the magnified image by the moire effect, and further enlarged by overlapping the lens array and the second micro pattern in the same manner. By performing authenticity determination using an image, it is possible to perform more reliable authenticity determination by performing multiple verifications on one information display medium.

  According to the second invention, the information display medium has an opening window in at least a part of the planar substrate, and the opening window has a light-transmitting lens array structure. By providing the lens array with such a configuration, it is possible to provide a lens array that can be used on the front and back surfaces even if the information display medium itself is made of an opaque material.

  According to the third aspect of the invention, at least a part of the planar substrate of the information display medium has a light transmitting property, for example, a plastic film, and the lens transmitting region is provided in the light transmitting region. doing. Since the lens array itself has a light-transmitting configuration, it is not necessary to provide an opening window in the information display medium by adopting a light-transmitting planar base material as the information display medium, and the base and lens A lens array that can be used on the front and back surfaces can be provided by, for example, attaching the array with a light-transmitting adhesive material.

  According to the fourth aspect of the invention, the lens array is composed of a microlens array having a circular or a cross-sectional structure consisting of a part of a circle, and each microlens is arranged in a square matrix or a triangular matrix. .

  By employing the lens array having such a configuration, when the first micro pattern or the second micro pattern and the lens array are overlapped, an enlarged image due to the moire effect can be easily found and authentication can be easily performed. It is done. When a microlens array is used as the lens array, the degree of image formation by the lens changes depending on the orientation of the microlens with respect to the micropattern.

  Therefore, when a microlens array is employed, enlarged images with different effects can be obtained between the first micropattern and the second micropattern.

  According to the fifth aspect of the invention, the lens array is composed of a prism lens array having a triangular cross section. Since the prism lens array with a triangular cross section exhibits the same optical effect when observed from both the front and back sides, the prism lens array is arranged on the first micro pattern and the prism lens array on the second micro pattern. The same optical effect can be expected in the case of the above. When the first micro pattern and the second micro pattern are the same pattern, the same enlarged image can be reproduced by placing the prism lens array.

  According to the sixth invention, the top of the lens array structure does not protrude from the surface of the planar substrate of the information display medium. With this configuration, even when a large number of information display media are stacked, the thickness of the lens array does not exceed the thickness of the banknote, so the total thickness of the information display medium does not change, However, there will be no problems such as collapse.

  According to the seventh invention, the first micro pattern or the second micro pattern is formed by printing ink. By forming a micropattern with printing ink, high-definition image expression can be realized, and at the same time, color expression can be realized. In addition, when other areas of the information display medium are similarly processed by printing, it is possible to express a design having high affinity with these areas.

  According to the eighth invention, at least one of the first micro pattern and the second micro pattern is formed of a fine structure that exhibits one of the functions of diffraction, light scattering, and light absorption. Microstructures with diffraction, light scattering, and light absorption are used alone as anti-counterfeiting media, but by adopting those microstructures as micropatterns, images can be captured only by overlapping lens arrays separately. Since it becomes visible, a higher anti-counterfeit effect can be realized.

  According to the ninth invention, the first enlarged image displayed by the superposition of the first micro pattern and the lens array, and the second enlarged image displayed by the superposition of the second micro pattern and the lens array, Displays the same information. In order to display the same information by the first enlarged image and the second enlarged image, it is necessary to process the first micro pattern and the second micro pattern with the same precision, and the same lens effect is exhibited on both sides. The lens array to be processed must be processed with high accuracy. Therefore, the difficulty of production is high and the forgery prevention effect is high.

In addition, if the same information is confirmed on both sides, the judgment criterion that the information display medium is authentic is easy for the judge to understand, and also has the advantage that it is easy for the judge to judge the authenticity. In addition, according to the tenth invention, the first enlarged image displayed by superimposing the first micro pattern and the lens array, and the second enlarged image displayed by superposing the second micro pattern and the lens array. Display different information. In order to display different information depending on the first enlarged image and the second enlarged image, it is necessary to perform different processing on the first micro pattern and the second micro pattern.

  Therefore, even when a person who tries to counterfeit the information display medium appears, it is possible to increase the time for counterfeiting. Moreover, the fact that different enlarged images can be adopted according to the information and design on the front and back of the information display medium contributes to an increase in the amount of information and an improvement in the eye catching effect.

  According to the eleventh aspect of the invention, the information display medium is folded, the enlarged image generated by the moire effect is visually observed by superimposing the lens array and the first micropattern, and the information display medium is further bent to the opposite side, There is provided an authenticity determination method for determining authenticity of the information display medium by visually observing the enlarged image by superimposing the second micropattern and the second micropattern.

  For example, an information display medium made of paper or a thin plastic substrate such as banknotes and various tickets can be easily folded and one surface of the information display medium can be overlaid so that the lens array is aligned on the micropattern. Thus, it is possible to easily display an enlarged image and to perform reliable authentication. Also, in the authenticity determination using the second micropattern arranged on the back surface, since the authenticity determination can be performed similarly by simply folding the information display medium to the opposite side, the authenticity determination can be performed a plurality of times in the same procedure.

1 is a plan view schematically showing an information display medium according to an aspect of the present invention. It is an expanded sectional view of the display body which followed the II-II line shown in FIG. It is a conceptual diagram which shows the principle of the enlarged image generation based on the moire effect by a lens array and a micro pattern. It is a perspective view which shows an example of the diffraction grating employable as a micro pattern. It is a perspective view which shows an example of the light-scattering structure employable as a micro pattern. It is a perspective view which shows an example of the light absorption structure employable as a micro pattern. It is sectional drawing which shows a mode that the lens array (micro lens array) and the micro pattern were piled up. It is sectional drawing which shows a mode that the lens array (micro lens array) and the micro pattern were piled up. It is sectional drawing which shows a mode that the lens array (micro lens array) and the micro pattern were piled up. It is sectional drawing which shows a mode that the lens array (micro lens array) and the micro pattern were piled up. It is sectional drawing which shows a mode that the lens array (prism lens array) and the micro pattern were piled up.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings. Note that, throughout all the drawings, the same reference numerals are given to components that exhibit the same or similar functions, and redundant descriptions are omitted.

<Configuration of information display medium>
FIG. 1 is a plan view schematically showing an information display medium according to an aspect of the present invention. 2 is a cross-sectional view of the information display medium shown in FIG. 1 taken along line II-II. 1 and 2, the X direction and the Y direction are parallel to the surface of the information display medium and are perpendicular to each other. The Z direction is a direction perpendicular to the X direction and the Y direction.

  As shown in FIG. 1, the information display medium 1 includes a lens array 20, a first micropattern region 30, and a second micropattern region 31. In FIG. 1, the first micropattern region 30 is provided on the surface 11 side of the planar substrate 10 of the information display medium 1. Moreover, since the 2nd micro pattern 31 is provided in the back surface 12 side of the planar base material 10 which is not shown in figure, it has shown with the dotted line. As shown in FIG. 2, the lens array 20 is configured by an opening window portion 13 partially provided on the information display medium 1.

  The planar substrate 10 is made of, for example, paper, a thin plastic substrate, or a composite material in which they are laminated, which can be folded and overlapped. Examples of the plastic substrate include a film or sheet made of a resin such as polyethylene terephthalate (PET) and polycarbonate (PC).

  The planar substrate 10 may have a light transmitting property or may be an opaque material that does not have a light transmitting property. By providing the opening window 13 on a part of the planar substrate, the lens array 20 can be provided even if the planar substrate 10 is made of an opaque material. On the other hand, if at least a part of the planar substrate 10 is light transmissive, the lens array 20 can be provided without providing the opening window portion 13. In this case, a method of sticking the lens array 20 to the planar substrate 10 or a method of processing the planar substrate 10 itself into a lens array shape can be employed.

The planar substrate 10 may have a single layer structure or a multilayer structure. Further, the planar substrate 10 may be subjected to antifouling treatment or antistatic treatment. When the planar substrate 10 is made of a plastic substrate, it may be further subjected to antireflection treatment, hard coat treatment, or the like. Good.

  The planar substrate 10 may be separately provided with a printing layer, a magnetic stripe region for performing machine reading, and an information transmitting / receiving member such as an IC chip.

<Configuration of Lens Array 20>
The lens array 20 has a light collecting function or an imaging function. Typical examples of structures that can be employed in the lens array 20 include micro structures such as a micro lens array 25, a prism lens array 26, a lenticular lens array, and a Fresnel lens array. Further, it is possible to employ a hologram in which the light condensing function or the imaging function is realized in an array by controlling the refractive index distribution in the material.

  As shown in FIG. 2, the lens array 20 includes a light transmissive substrate 21 and a plurality of lens elements 22. The light transmissive substrate 21 is, for example, a film or sheet made of a resin such as PET or PC. The light transmissive substrate 21 can be omitted.

  The lens element 22 is, for example, a microlens (spherical lens) having a circular cross section or a partial shape of a circle. The lens element 22 may be an aspheric lens or a rectangular lens. A spherical lens is defined as a lens having a surface formed of a part of a spherical surface. An aspheric lens is a lens having a surface composed of a part of a spherical surface whose shape is slightly shifted. The rectangular lens is a lens having a rectangular or square cross section parallel to the Z direction, and forms, for example, a lattice or striped lens array when observed from a direction parallel to the Z direction.

  When the lens element 22 is a convex lens such as a spherical lens or an aspherical lens, when the information display medium is bent and the lens element and the surface of the micropattern described later are overlapped, the focal point of the lens element to the surface of the micropattern When the distance is shortened, a clearer image can be displayed. The distance from the focal point of the lens element to the surface of the micropattern is, for example, the focal length of the lens element, the thickness or refractive index of the light-transmitting substrate, or the focal length of the lens element and the thickness or refraction of the light-transmitting substrate. Can be controlled by rate.

  When the lens element 22 is a rectangular lens and these constitute a lens array having a lattice shape or a stripe shape when observed from a direction parallel to the Z direction, there is no focal point. Therefore, in this case, it is not necessary to strictly control the distance from the lens array to the surface of the micropattern.

  When a microlens is employed as the lens element 22, a typical example is a microlens having a diameter of 20 to 200 μm and a structural height of about 10 to 100 μm arranged regularly in a square matrix or a triangular matrix. If it has an imaging function, it does not stay in this range.

In addition, a prism lens array 26 may be employed as the lens element 22. The prism lens array 26 has a configuration in which a plurality of elongated structures having a triangular cross section having a pitch of about 10 to 200 μm and a structure height of about 10 to 200 μm are arranged adjacent to each other. You can also. The lenticular lens array has a configuration in which a plurality of elongated structures each having a pitch of 10 to 200 μm and a structural height of about 10 to 200 μm and having a semi-cylindrical cross section are arranged.

When the prism lens array 26 or the lenticular lens array is employed as the lens element 22, a three-dimensional image that produces a sense of depth can be displayed in combination with a micro pattern. In addition, the visual effect can be changed by partially modulating the size and arrangement interval of the lens elements or by partially changing the focal length of the lens elements.

  Further, a Fresnel lens can be adopted as the lens element 22. A Fresnel lens is a lens in which a normal convex lens is divided into concentric circular regions to reduce the thickness, and a Fresnel lens array in which a plurality of such lenses are arranged in an array.

  The lens array 20 can be formed, for example, by pressing a mold having a plurality of lens structures against a resin. For example, the lens array 20 is a method in which a mold provided with a shape to be paired with the lens element 22 is pressed against a thermoplastic resin formed on a light-transmitting substrate 21 while heating, that is, heat embossing. Obtained by law.

  Alternatively, the lens array 20 applies an ultraviolet curable resin to the light transmissive substrate 21, and cures the ultraviolet curable resin by irradiating ultraviolet rays from the light transmissive substrate 21 side while pressing a mold on the resin. It can be formed by a method of removing the mold.

  Further, the lens array 20 may be directly attached on the planar substrate 10 of the information display medium. By providing the lens array 20 directly on the planar substrate, the light transmissive substrate 21 can be omitted. Further, the lens array 20 may directly process the planar substrate 10. A light-transmitting material is used as the planar substrate 10, and the surface of the planar substrate 10 is directly made into a lens shape by heat and / or pressure with a mold provided with a plurality of lens structures, for example. Also good.

  As a material of the lens array 20, for example, a thermoplastic resin material such as an acrylic resin, a polycarbonate resin, a styrene resin, and an acrylic / styrene copolymer resin or an ultraviolet curable resin can be used. As a material of the lens array 20, an inorganic material containing a silicate may be used instead of using a resin.

<About the structure of the micro pattern area>
In the micro pattern area 30, as shown in FIG. 3, unit images 32 are regularly arranged corresponding to the unit areas 33. A plurality of circles shown in FIG. 3 is a virtual illustration of the lens element 22 when a microlens array 25 composed of microlenses arranged in a square matrix is placed on the micropattern region 30 as a lens array. . The arrangement interval of the lens elements 22 and the arrangement interval of the unit regions 33 are equal, and the moiré effect is generated between the micropattern and the lens array 20 by making the column of the unit images 32 slightly different from the column of the lens elements 22. As a result, it is possible to display an enlarged image obtained by combining the plurality of unit images 32 and enlarging the lens array 20.

  The enlargement ratio of the enlarged image changes according to the angle α formed between the row of unit images 32 and the row of lens elements 22. The smaller the angle α, the larger the enlargement factor, and the larger the angle α, the smaller the enlargement factor. Here, when the angle α is set to 0 °, the enlarged image becomes infinite and the entire image cannot be observed. When displaying an enlarged image by the moire effect on the information display medium, the angle α may be set to several degrees, typically about 2 °.

  The unit image formed in the micro pattern area 30 can be processed by printing. By forming micropatterns with printing ink, high-definition image expression is possible, and color expression can be realized. In addition, when other areas of the information display medium are similarly processed by printing, it is possible to express a design having high affinity with these areas.

Further, it is possible to construct a unit image by adopting a micro structure that exhibits at least one of the functions of diffraction, light scattering, and light absorption in the micro pattern region 30.

  Examples of the fine structure that can be employed in the micropattern region 30 include a diffraction grating 40 having a concavo-convex structure with a periodic cross section as shown in FIG. The diffraction grating emits a rainbow-colored spectral color by diffraction, and can realize a function of displaying an image whose color or pattern changes according to the observation conditions such as the position of the light source and the observation angle of the observer.

  Another structure that can be employed in the micropattern region 30 is a light scattering structure. As shown in the perspective view of FIG. 5, the light scattering structure 41 is typically one in which a plurality of irregular shapes having different sizes, shapes, and structure heights are irregularly arranged. The light incident on the light scattering structure 41 is irregularly reflected in all directions and appears white or cloudy when observed. The light scattering structure 41 typically has a width of 3 μm or more and a height of 1 μm or more, and is larger than the diffraction grating 40 or a light absorption structure 42 described later. Moreover, the size, arrangement interval, and shape are not uniform. Therefore, the effect of scattering light is obtained.

  Further, as a structure that can be employed in the micropattern region 30, there is a light absorption structure 42 having a fine concavo-convex structure. The light absorbing structure 42 is typically a conical structure as shown in the perspective view of FIG. 6 or a structure in which pyramidal structures are regularly arranged, and the structure has a wavelength less than the wavelength of visible light (for example, The light absorption effect is higher when the height of the structure is, for example, 300 μm or more and higher. The light absorbing structure 42 formed in the above specifications has a function of preventing or reducing the reflection of incident visible light, and looks black or dark gray when observed.

The micropattern region 30 in which these fine structures are formed may have a form in which the fine structure is exposed to the air interface, or a form in which the surface is covered with a light-transmitting embedding resin or the like. Also good. These fine structures are further made of a light reflecting layer made of a metal such as gold, silver, aluminum or copper, or a dielectric such as titanium oxide (TiO ₂ ) or zinc sulfide (ZnS) so as to follow the surface of the fine structure. Visibility can be improved by providing about 10 to 100 nm, for example.

  In order to realize these fine structures, for example, a photolithography process can be used. It is possible to obtain a desired fine structure by exposing and developing a photosensitive resist coated substantially uniformly on a planar substrate (a glass substrate is generally used) by a charged particle beam such as an electron beam or a laser. it can.

  If the photosensitive resist is called a positive resist, the portion irradiated with the charged particle beam dissolves after development, and if the photosensitive resist is called a negative resist, the portion irradiated with the charged particle beam remains after development. The unirradiated part dissolves. The substrate is placed on an XY stage whose position can be adjusted with high accuracy, and the position where the charged particle beam is irradiated is determined while moving the stage under computer control.

  Since the fine structure by the photosensitive resist is fragile, the substrate thus obtained is not suitable as a stamper for mass production, and a metal stamper is produced from this substrate as an original plate by a method such as electroforming. . Electroforming is a type of surface treatment technology that forms a metal film by reducing the power of electrons by immersing an electroformed object in a predetermined aqueous solution and energizing it. By using such a method, The fine concavo-convex structure provided on the surface of the original plate can be transferred and molded as a metal plate with high accuracy.

The surface of the object of electroforming needs to be able to be energized. Generally, the photosensitive resist does not conduct electricity. Therefore, before electroforming, metal is deposited on the surface of the structure by vapor deposition such as sputtering or vacuum evaporation. A thin film is provided in advance.

  The metal stamper is then used as a matrix to replicate the microstructure. That is, first, a thermoplastic resin or a photocurable resin is applied onto a transparent substrate made of, for example, PET or PC. Next, a metal stamper is brought into close contact with the coating film, and heat or light is applied to the resin layer in this state. After the resin is cured, the microstructure can be replicated by peeling the metal stamper from the cured resin.

  Generally, the base material and the resin material for formation are transparent. Therefore, usually, a reflective layer is formed on a resin layer provided with a fine structure by depositing a metal such as aluminum or a dielectric in a single layer or multiple layers by vapor deposition or the like.

  The micro-pattern region 30 composed of the fine structure can be formed by pasting the fine structure produced by such a process onto a planar base material of the information display medium via an adhesive material, for example.

  The fine structure realized by such a process can realize a fine pattern with extremely high resolution as compared with printing, and is suitable for use as a micro pattern. In addition, since the microstructure itself exhibits special optical effects that are not displayed by ordinary printing inks such as diffraction, light scattering, and light absorption, the magnified image displayed by the lens array is also highly effective in preventing counterfeiting. The catch effect is high.

  Note that the micropattern region 30 may have a structure in which a plurality of fine structures accompanied with printing, diffraction, light scattering, light absorption, and the like are combined.

<About the embodiment>
FIG. 7 is a cross-sectional view showing a state in which the planar substrate 10 is bent and held so that the lens array 20 is placed on the first micropattern region 30 in the information display medium 1 of the present invention. Here, the lens array 20 is a microlens array 25 as an example, and the lens element 22 has a convex shape on the back surface 12 side of the planar substrate. Here, in FIG. 7, the lens array 20 is provided inside the opening window 13 which is a through hole provided in the planar substrate 10.

  When the planar substrate 10 is composed of a light-transmitting material, the lens array 20 is configured by adhering to the planar substrate 10 via an adhesive material or the like as shown in FIG. You can also. Furthermore, as shown in FIG. 9, the lens array 20 can also be realized by directly processing the planar substrate 10 having optical transparency.

  A first enlarged image due to the moire effect by superimposing a plurality of unit images 32 provided on the first micropattern area 30 by placing the lens array 20 on the first micropattern area 30 and the microlens array 25. And the observer can perceive the image. Since the magnification ratio of the first magnified image shown in FIG. 3 is determined by the angle α formed by the columns of the plurality of unit images 32 and the columns of the microlens array 25, the observer appropriately selects the first micropattern region 30. By sliding the lens array 20 on the upper side, it is possible to easily find the overlapping angle α that provides an enlargement ratio at which the enlarged image is easily visible.

FIG. 10 is a conceptual diagram when the information display medium 1 is bent in the direction opposite to that in FIG. 7 and held so that the lens array 20 is placed on the second micropattern region 31. In this case, the microlens array 25 is opposite to that in FIG. 7 and is convex on the back surface 12 side of the planar substrate. In this case, the focal position is changed by changing the direction of the lens with respect to the micropattern, and the enlarged image to be displayed is changed by changing the action of the lens. Here, even if the first micro pattern area 30 and the second micro pattern area 31 have the same pattern, the images displayed are not the same because the lens element 22 is in the reverse direction.

  Since the micro pattern areas are on both sides of the information display medium, different enlarged images can be obtained by one lens array, and authenticity determination can be performed a plurality of times. Here, since the information display medium is provided with a lens array, it is not necessary to prepare a special verification instrument or the like, and there is also an advantage that authentication can be performed.

  FIG. 11 shows an example in which the lens array 20 is composed of a prism lens array 26 composed of lenses having a triangular cross section. The prism lens array 26 is composed of two types of resins 27 and 28 having different refractive indexes, and the surface thereof is smooth. When the lens array has such a configuration, the same optical effect is expected whether the lens array is placed on the front surface side of the planar substrate or the lens array is placed on the back surface side of the planar substrate. it can. Here, when the same image is used for the first micro pattern region 30 and the second micro pattern region 31, it is possible to display the same enlarged image on both the front and back sides.

  Thus, depending on the configuration and material, it is possible to adopt a lens array having smooth surfaces. By adopting a lens with a smooth surface, it is possible to prevent dust and foreign matters from being mixed even during long-term use, and it is possible to prevent lens loss due to external factors.

DESCRIPTION OF SYMBOLS 1 ... Information display medium 10 ... Planar base material 11 ... Front surface 12 (planar base material) ... Back surface (planar base material) 13 ... Opening window part 20 ... Lens array 21 ... Light transmissive substrate 22 ... Lens element 25 ... Micro lens array 26 ... Prism lens array 27 ... Resin 28 ... Resin 30 ... First micro pattern area 31 ... Second micropattern region 32 ... Unit image 33 ... Unit region 40 ... Diffraction grating 41 ... Light scattering structure 42 ... Light absorption structure

Claims (11)

An information display medium provided with a light-transmitting lens array structure that can be observed from the front and back on a planar substrate,
A first micro pattern region that displays an enlarged image due to the moire effect generated by superimposing with the lens array on a part of the surface of the substrate;
An information display medium having a second micro pattern region for displaying an enlarged image by a moire effect generated by superimposing with the lens array on a part of the back surface of the substrate.   The information display medium according to claim 1, wherein the planar substrate has an opening window portion, and the lens array is provided in the opening window portion.   2. The information display medium according to claim 1, wherein at least a part of the planar substrate has a light-transmitting region, and the lens array is provided in the light-transmitting region.   4. The lens array according to claim 1, wherein the lens array is a microlens array having a cross-sectional structure composed of a circle or a part of a circle, and each lens is arranged in a square matrix or a triangular matrix. The information display medium according to claim 1.   The information display medium according to claim 1, wherein the lens array is a prism lens array having a triangular cross section.   The information display medium according to claim 1, wherein a top portion of the lens array structure does not protrude from a surface of the planar substrate.   Any one of the first micropattern and the second micropattern, or the first micropattern and the second micropattern is formed of printing ink. The information display medium according to one item.   Any one of the first micropattern and the second micropattern, or the first micropattern and the second micropattern is formed from a fine structure having a function of diffraction, light scattering, or light absorption. The information display medium according to claim 1, wherein the information display medium is a display medium. An enlarged image by a moire effect generated by superimposing the first micropattern and the lens array;
9. The information display medium according to claim 1, wherein the same information is displayed by an enlarged image by a moire effect generated by superimposing the second micropattern and the lens array. An enlarged image by a moire effect generated by superimposing the first micropattern and the lens array;
9. The information display medium according to claim 1, wherein different information is displayed in an enlarged image due to a moire effect generated by superimposing the second micropattern and the lens array. Bending the information display medium, an enlarged image due to a moire effect that occurs when the lens array and the first micropattern are superimposed,
The information display medium according to any one of claims 1 to 10, wherein the information display medium is bent by the opposite side and an enlarged image by a moire effect generated when the lens array and the second micropattern are overlapped. An authenticity determination method characterized by determining authenticity.

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