JP2009276518A - Optical element, adhesive label, transfer foil, article with label and discrimination device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technology for obtaining better forgery prevention effect. <P>SOLUTION: An optical element 10 comprises: a light transmission layer in which one major face contains an interface section in which a plurality of concave or convex sections arranged in one dimension or two dimensions are prepared with a distance between centers of 200 to 500 nm; and a light transmission reflection layer of a single layer structure, in which at least a part of the interface section is covered. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a forgery prevention technique.

  It is desirable that authentication items such as cash cards, credit cards and passports, and securities such as gift certificates and stock certificates are difficult to counterfeit. Therefore, conventionally, a label that is difficult to forge or counterfeit and easily distinguishable from counterfeit or counterfeit is attached to such an article in order to prevent counterfeiting. Such a label is described in Patent Document 1, for example.

In recent years, the distribution of counterfeit products has been regarded as a problem for items other than certified items and securities. Therefore, the opportunity to apply the above-described anti-counterfeiting technology with respect to certified articles and securities is increasing.
JP 2005-91699 A

  By the way, many optical elements used as anti-counterfeit labels have a problem that it is relatively easy for an observer to recognize that anti-counterfeit technology is applied. If the application of the anti-counterfeiting technology is realized, there is a high possibility that the optical element is illegally copied or altered. That is, an excellent anti-counterfeit effect cannot be achieved.

  Accordingly, an object of the present invention is to realize a better anti-counterfeit effect.

  According to the first aspect of the present invention, one principal surface includes an interface portion in which a plurality of concave or convex portions arranged one-dimensionally or two-dimensionally are provided at a center-to-center distance of 200 nm to 500 nm. And an optical element comprising a light-transmissive reflective layer having a single-layer structure covering at least a part of the interface.

  According to a second aspect of the present invention, there is provided an adhesive label comprising the optical element according to the first aspect and an adhesive layer provided on the optical element.

  According to a third aspect of the present invention, there is provided a transfer foil comprising the optical element according to the first aspect and a support layer that releasably supports the optical element.

  According to a fourth aspect of the present invention, there is provided a labeled article characterized by comprising the optical element according to the first aspect and an article supporting the optical element.

  According to a fifth aspect of the present invention, there is provided a discrimination device for discriminating a discrimination object between a genuine product and a non-genuine product, a light source that emits illumination light, a photodetector, and the photodetector An output unit that outputs discrimination information according to the output of the output, wherein the output unit is parallel to a first plane perpendicular to the surface of the discrimination target and is normal to the normal of the first surface The illumination light is irradiated from a first direction inclined and the orthographic projection onto the first plane is defined as an angle range on the first direction side with respect to the normal line in an angular range in the first plane. When the light detector does not detect light under a first measurement condition in which the light detector detects light emitted from the discrimination target in a second direction within a negative angle range, A first operation for outputting, as discrimination information, information indicating that the discrimination object is a non-genuine product; When the light detector detects light under measurement conditions, at least one of a second operation of outputting information indicating that the discrimination target is a genuine product is executed as the discrimination information. Is provided.

  According to the present invention, it is possible to realize a better anti-counterfeit effect.

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

  FIG. 1 is a plan view schematically showing an optical element according to an aspect of the present invention. FIG. 2 is a sectional view taken along line II-II of the optical element shown in FIG.

  The optical element 10 includes a laminate of a light transmission layer 100 and a light transmission reflection layer 200 having a single layer structure. In the example shown in FIG. 2, the light transmissive layer 100 side is the front side, and the light transmissive reflective layer 200 side is the back side. The interface between the light transmissive layer 100 and the light transmissive reflective layer 200 includes a first interface portion IA and a second interface portion IB. As will be described later, the first interface portion IA is provided with a plurality of concave portions or convex portions. These concave portions or convex portions emit diffracted light in a specific direction when irradiated with light. The second interface part IB is a flat surface.

  In the following description, a portion of the optical element 10 corresponding to the first interface portion IA is referred to as a first portion 10A, and a portion of the optical element 10 corresponding to the second interface portion IB is referred to as a second portion 10B.

  The term “light transmittance” means that the total light transmittance is 80% or more. The total light transmittance is measured in accordance with Japanese Industrial Standard JIS K7361-1: 1997 (ISO13468-1: 1996) “Plastics—Testing method of total light transmittance of transparent material—Part 1: Single beam method”. Value.

  Furthermore, the term “transparent” means that the total light transmittance is 85% or more and the haze value is 10% or less. In addition, a haze value is a measured value based on Japanese Industrial Standard JIS K7136: 2000 (ISO14782: 1999) "How to determine haze of plastic-transparent material".

  The light transmission layer 100 is typically transparent or nearly transparent. However, the light transmission layer 100 may have a slight light scattering property in a range where the visibility or detection sensitivity of the diffracted light is not insufficient.

  As a material of the light transmission layer 100, for example, a resin having a light transmission property can be used. For example, when a thermoplastic resin or a photocurable resin is used, the light transmission layer 100 in which a concave portion or a convex portion is provided on one main surface can be easily formed by transfer using an original plate.

  The light transmissive reflective layer 200 has a single layer structure.

  The light transmissive reflective layer 200 is typically transparent or nearly transparent. The light transmissive reflective layer 200 may have a slight light scattering property in a range where the visibility or detection sensitivity of diffracted light is not insufficient.

  The light transmissive reflective layer 200 has a refractive index different from that of the light transmissive layer 100. Therefore, the interface between the light transmissive reflective layer 200 and the light transmissive layer 100 has light reflectivity.

  The total light transmittance of the light transmissive reflective layer 200 is typically 80% or more. Further, the reflectance at the interface between the light transmission layer 100 and the light transmission reflection layer 200 is typically in the range of 1.5% to 20%.

  The light transmissive reflective layer 200 is made of an inorganic material, for example. As this inorganic substance, a metal, a metal compound, or a nonmetallic compound can be used, for example. As the metal, for example, aluminum can be used. As the metal compound, for example, an alloy, a metal oxide such as titanium oxide and alumina, a metal sulfide such as zinc sulfide, or a metal nitride can be used. As the nonmetallic compound, for example, a nonmetallic oxide such as silica can be used.

  In this case, the light transmissive reflective layer 200 is formed, for example, by vapor deposition of the inorganic material. As the vapor deposition method, for example, a vacuum vapor deposition method, a sputtering method, or an ion plating method can be used.

  A resin may be used as the material of the light transmissive reflective layer 200. In this case, the light transmissive reflective layer 200 can be formed more easily than when the light transmissive reflective layer 200 is formed by vapor deposition of an inorganic substance.

  Alternatively, as the material of the light transmissive reflective layer 200, a material in which granular inorganic substances are uniformly dispersed in a resin may be used. In this case, the total light transmittance of the light-transmissive reflective layer 200 and the reflectance at the previous interface can be optimized by adjusting the size and density of the inorganic substance in the resin. As this inorganic substance, for example, the materials listed above can be used.

  The refractive index of the light transmissive reflective layer 200 is typically about 0.25 or more smaller than the refractive index of the light transmissive layer 100 or about 0.4 or larger than the refractive index of the light transmissive layer 100. . Thus, the reflectance at the interface between the light transmissive layer 100 and the light transmissive reflective layer 200 is about 2% or more, and a bright display on the optical element 10 is possible.

  When a material having a large light absorption rate such as a metal or an alloy is used, a sufficient total light transmittance can be achieved by forming a thin film. When a material having a large light absorption rate is used, the thickness of the light transmissive reflective layer 200 is, for example, in the range of 10 nm to 200 nm. On the other hand, when a transparent material is used, the thickness of the light transmissive reflective layer 200 is, for example, in the range of 500 nm to 50 μm.

  As described above, the light transmission layer 100 and the light transmission reflection layer 200 are typically transparent or almost transparent. That is, the light transmissive layer 100 and the light transmissive reflective layer 200 do not emit scattered light with such a high intensity as to affect the visual recognition or detection of the diffracted light emitted from the concave portion or the convex portion.

  Further, as will be described in detail later, the concave portions or convex portions included in the first interface portion IA are regularly arranged with a small center distance. Therefore, the first interface IA emits diffracted light only in a specific direction and angle, and does not emit diffracted light in other directions and angles. Therefore, under the condition where the diffracted light is not visually recognized or detected, the first portion 10A including the first interface portion IA is observed in substantially the same manner as the second portion 10B including the second interface portion IB which is a flat surface. Is done. That is, under this condition, it is difficult to distinguish the first portion 10A and the second portion 10B from each other. Therefore, under this condition, it is difficult to distinguish the optical element 10 from a layer provided for the purpose other than forgery prevention such as a transparent protective layer. Therefore, it is difficult to realize that the first interface portion IA has a concave portion or a convex portion, that is, the forgery prevention technology is applied to the optical element 10.

  In addition, when the reflective layer which does not have a light transmittance is used instead of the light transmissive reflective layer 200, the 1st part 10A looks black or gray. In this case, the first portion 10A and the second portion 10B are easily distinguished from each other. Therefore, it is relatively easy to realize that the first interface portion IA has a concave portion or a convex portion, that is, the forgery prevention technology is applied to the optical element 10. In this case, there may be a limitation on the design of the optical element 10 and the article that supports the optical element 10.

  Further, as described above, the light transmissive reflective layer 200 has a single layer structure. Therefore, the optical element 10 is less likely to generate interference light due to repeated reflection interference as compared with the case where the light transmissive reflective layer 200 is a multilayer film. In other words, the light transmissive reflective layer 200 hardly generates interference light that adversely affects the visual recognition or detection of the diffracted light emitted from the first interface IA. Further, the light transmissive reflective layer 200 has little adverse effect on the optical element 10 and the design of the article supporting the optical element 10.

  The optical element 10 may further include a printing layer. This printed layer may be patterned or unpatterned. In the case of using a patterned print layer, the print layer is, for example, the front side of the light transmissive layer 100, between the light transmissive layer 100 and the light transmissive reflective layer 200, or the back side of the light transmissive reflective layer 200. To form. When using an unpatterned printed layer, the printed layer is typically formed on the back side of the light transmissive reflective layer 200.

  In these cases, the optical element 10 looks like a normal printed material under the condition where the above-described diffracted light is not visually recognized or detected. Moreover, compared with the case where the optical element 10 does not include the printing layer, the boundary between the first portion 10A and the second portion 10B is more difficult to understand, and it is more difficult to distinguish between the two. Therefore, by providing a printing layer on the optical element 10, it is more appreciated that the first interface portion IA is provided with a concave portion or a convex portion, that is, that the anti-counterfeit technology is applied to the optical element 10. It becomes possible to make it difficult.

  Further, as described above, the concave portion or the convex portion is formed in the first interface portion IA. Therefore, compared with the case where the concave portion or the convex portion is exposed on the surface, the damage is less likely to occur. In this case, it becomes more difficult to duplicate the concave portion or the convex portion.

  Hereinafter, structures that can be employed in the first interface IA will be described. As described above, the first interface portion IA is provided with a plurality of concave portions or convex portions.

  As described above, the second interface part IB is a flat surface. The second interface part IB can be omitted.

  FIG. 3 is an enlarged perspective view showing an example of a structure that can be employed in the first interface portion of the optical element shown in FIGS. 1 and 2. In the example shown in FIG. 3, the recesses or projections RP are two-dimensionally arranged.

  The concave portions or the convex portions RP are regularly arranged. Therefore, the 1st interface part IA provided with the recessed part or the convex part RP can inject | emit diffracted light, when irradiating illumination light. The concave portion or the convex portion RP has, for example, a square lattice, a rectangular lattice, or a triangular lattice. By controlling the arrangement of the concave portions or the convex portions RP, it is possible to arbitrarily adjust the emission angle and the emission direction of the diffracted light emitted from the first interface portion IA. In FIG. 3, as an example, a case where the concave portions or the convex portions are two-dimensionally arranged in the X direction and the Y direction orthogonal to each other to form a square lattice is illustrated.

  In addition, each of the concave portion or the convex portion RP can have various shapes.

  For example, each of the concave portion or the convex portion RP may have a forward tapered shape such as a pyramid, a cone, and a semi-spindle shape. In this case, at least a part of the light incident on the concave portion or the convex portion RP is reflected a plurality of times on the surface of the concave portion or the convex portion RP. In each of these reflections, at least a part of the incident light is transmitted through the surface of the concave portion or the convex portion RP, and is absorbed by the concave portion or the convex portion RP, or is absorbed by the structure located on the back side thereof. Accordingly, in this case, the reflectance of the first interface portion IA can be kept low based on the repeated reflection.

  Alternatively, each of the concave portion or the convex portion RP may have a columnar shape such as a prismatic shape or a cylindrical shape. In this case, each of the concave portion or the convex portion RP has a flat surface substantially parallel to the second interface portion IB. Therefore, the difference between the reflectance at the first interface IA and the reflectance at the second interface IB can be kept low. Therefore, in this case, it becomes more difficult to distinguish the first portion 10A and the second portion 10B under normal observation conditions. Therefore, it can be made difficult to realize that the first interface portion IA includes the concave portion or the convex portion RP, that is, the forgery prevention technique is applied to the optical element 10.

  Thus, the reflectance of the first interface portion IA and the like can be appropriately adjusted by appropriately selecting the shape of each of the concave portion or the convex portion RP.

  FIG. 4 is an enlarged perspective view showing another example of a structure that can be employed in the first interface portion of the optical element shown in FIGS. 1 and 2. In the example shown in FIG. 4, the concave portion or the convex portion RP is a relief type diffraction grating in which a plurality of grooves are arranged one-dimensionally.

  In this case, it is possible to arbitrarily adjust the emission angle and emission direction of the diffracted light emitted from the first interface IA by controlling the lattice constant, orientation, depth, etc. of the plurality of grooves. it can.

  The term “diffraction grating” means a structure that generates a diffracted wave when irradiated with illumination light such as natural light, and is recorded on a hologram in addition to a normal diffraction grating in which a plurality of grooves are arranged in parallel and at equal intervals. Interference fringes are also included.

  The concave portion or the convex portion RP is arranged with a center-to-center distance of 200 nm to 500 nm. In this case, as will be described later, it is relatively easy to distinguish between genuine products and non-genuine products by visually observing or detecting diffracted light emitted from the first interface IA.

  Further, the depth or height of the concave portion or the convex portion RP is set to be substantially constant in order to suppress light scattering. The depth or height of the concave portion or convex portion RP is typically 100 nm or more.

  Thus, the first interface IA has a fine structure. Therefore, it is relatively difficult to accurately analyze the structure provided in the first interface portion IA from the completed optical element 10. Even if the previous structure can be analyzed from the completed optical element 10, it is difficult to forge or imitate the optical element including this fine structure.

  Next, the visual effect of the optical element 10 will be further described.

  FIG. 5 is a diagram schematically showing how the first interface emits diffracted light. In FIG. 5, L1 indicates illumination light, L2 indicates regular reflection light or zero-order diffracted light, and L3 indicates first-order diffracted light.

  In the first interface portion IA, the concave portions or the convex portions RP are regularly arranged. Therefore, when the first interface IA is illuminated, strong diffracted light is emitted in a specific direction with respect to the traveling direction of the illumination light that is incident light.

  The most representative diffracted light is first-order diffracted light. The second-order or higher-order diffracted light has a significantly lower intensity than the first-order diffracted light. For this reason, the influence of higher-order diffracted light on visual recognition and detection is negligible.

  The emission angle β of the first-order diffracted light can be calculated from the following equation (1) when the light travels in a plane parallel to the normal line N of the first interface IA.

d = λ / (sin α−sin β) (1)
In this formula (1), d represents the distance between the centers of the concave or convex portions RP, and λ represents the wavelengths of incident light and diffracted light. Α represents the exit angle of 0th-order diffracted light, that is, transmitted light or specularly reflected light.

  The angles α and β define a clockwise direction from the normal N as a positive direction. An angle range of −90 ° to 0 ° with respect to the normal N is referred to as a “negative angle range”, and an angle range of 0 ° to 90 ° is referred to as a “positive angle range”. Further, it is assumed that the emission angle α belongs to a positive angle range. That is, it is assumed that 0 ° <α <90 °.

  As is clear from the equation (1), the emission angle β of the first-order diffracted light changes according to the wavelength λ. That is, the concave portion or the convex portion RP has a function as a spectroscope. Therefore, when the illumination light is white light, when the observation angle is changed in a plane parallel to the normal line N, the color visually recognized by the observer changes.

  As can be seen from the equation (1), when the center-to-center distance d is smaller than the wavelength λ of the incident light, the emission angle β can be a negative value with respect to an arbitrary incident angle −α. That is, in this case, when the incident light L1 belongs to the negative angle range, the first-order diffracted light L3 also belongs to the negative angle range. Therefore, as will be described below, the first interface IA does not emit the first-order diffracted light having a visible light wavelength in the positive angle range, or the first-order diffracted light emitted in this angle range has a low visibility. It can be light only.

  As described above, the concave portion or the convex portion RP is arranged at the center distance d within the range of 200 nm to 500 nm.

  First, let us consider a case where the center-to-center distance d is not more than the shortest wavelength of visible light, for example, not more than 400 nm. In this case, as is apparent from the equation (1), the emission angle β is a negative value with respect to an arbitrary visible light wavelength λ and an angle α. That is, the first interface IA does not emit the first-order diffracted light having the visible light wavelength in the positive angle range.

  Therefore, in this case, even when the first portion 10A is observed under white light, the first-order diffracted light L3 is not visually recognized in the positive angle range. That is, only when the first portion 10A is observed from the light source side of the incident light L1, the diffracted light L3 from the first interface IA is visually recognized. Therefore, it is difficult to realize that the first interface portion IA is provided with the concave portion or the convex portion RP, that is, the forgery prevention technique is applied to the first interface portion IA. Further, the authenticity of the optical element can be determined by visually observing or detecting the diffracted light emitted at a specific angle and direction. That is, an excellent anti-counterfeit effect can be achieved.

  Next, consider a case where the center-to-center distance d is equal to or greater than the shortest wavelength of visible light, for example, in the range of 400 nm to 500 nm. In this case, as is apparent from the equation (1), the emission angle β may be a positive value for incident light having a wavelength shorter than 500 nm. However, in this case, the emitted first-order diffracted light L3 is only light having a wavelength shorter than 500 nm, that is, only blue light having low visibility.

  Therefore, in this case, even when the first portion 10A is observed under white light, the diffracted light L3 having a wavelength with high visibility is not visually recognized in the positive angle range. That is, the diffracted light L3 with high visibility is visually recognized only when the first portion 10A is observed from the light source side of the incident light L1. Therefore, similarly to the above case, it is difficult to realize that the forgery prevention technology is applied to the first interface portion IA. Further, the authenticity of the optical element can be determined relatively easily by visually recognizing or detecting the diffracted light with high visibility. That is, even in this case, an excellent anti-counterfeit effect can be achieved.

  The image displayed on the optical element 10 may be composed of a plurality of pixels arranged two-dimensionally. In this case, a relatively complex image can be displayed by making at least one of the shape, depth or height, center-to-center distance, and arrangement pattern of the concave portion or the convex portion RP different between these pixels. .

  FIG. 6 is a plan view schematically showing an example of an optical element having a display surface composed of a plurality of pixels arranged in a matrix.

  In the optical element 10, a display surface is configured by 25 pixels PX11 to PX15, PX21 to PX25, PX31 to PX35, PX41 to PX45, and PX51 to PX55 arranged in a matrix. PX11 to PX15, PX21, PX25, PX31, PX35, PX41, PX45, PX51 to PX55 have the same structure, PX22, PX32 to PX34, and PX42 have the same structure, PX23, PX24, PX43 and PX44 have the same structure. Then, a first pixel group consisting of PX11 to PX15, PX21, PX25, PX31, PX35, PX41, PX45, PX51 to PX55, a second pixel group consisting of PX22, PX32 to PX34 and PX42, and PX23, PX24, PX43 and The third pixel group composed of PX44 is different in the structure of the concave portion or the convex portion RP constituting each pixel.

  In FIG. 6, as an example, each pixel constituting the first pixel group is composed of concave portions or convex portions arranged in a square lattice shape, and each pixel constituting the second pixel group is a relief composed of a plurality of grooves. Each pixel which comprises a type | mold diffraction grating and comprises a 3rd pixel group has drawn the case where it consists of a recessed part or a convex part arrange | positioned at rectangular grid | lattice form.

  In this case, it is possible to display images of different colors and brightness in each of the first to third pixel groups according to the viewing angle and viewing direction of the optical element 10. That is, the optical element 10 can display a more complicated and fine image, and the forgery prevention effect can be further improved.

  The optical element 10 described with reference to FIGS. 1 to 6 may be used as a part of an adhesive label, a transfer foil, or the like.

  FIG. 7 is a cross-sectional view schematically showing an adhesive label according to one embodiment of the present invention.

  The pressure-sensitive adhesive label 20 includes an optical element 10 and an adhesive layer 300 provided on the optical element 10. As an example, FIG. 7 shows a case where an adhesive layer 300 is provided on the back surface of the light-transmissive reflective layer 200 of the optical element 10 shown in FIG.

  When the adhesive layer 300 is provided, the surface of the light transmissive reflective layer 200 can be prevented from being exposed. The shape of the surface of the light transmissive reflective layer 200 is generally substantially equal to the shape of the interface between the light transmissive layer 100 and the light transmissive reflective layer 200. Therefore, by using the optical element 10 as a part of the pressure-sensitive adhesive label 20, it is possible to make it difficult to duplicate the concave portion or convex portion of the previous interface. In the optical element 10, when the light transmissive layer 100 side is the back surface side and the light transmissive reflective layer 200 side is the front surface side, the adhesive layer 300 is formed on the light transmissive layer 100.

  For example, the adhesive label 20 is attached to an article whose authenticity is to be confirmed, or is attached to another article such as a base material of a tag to be attached to the article. Thereby, the forgery prevention effect can be provided to the said article | item.

  Note that the adhesive label 20 can be provided with an anti-sticking function by cutting the light-transmissive reflective layer 200 or further providing a brittle layer between the optical element 10 and the adhesive layer 300. Thereby, the further superior forgery prevention effect can be achieved.

  FIG. 8 is a cross-sectional view schematically showing a transfer foil according to an aspect of the present invention.

  The transfer foil 30 includes the optical element 10 and a support layer 400 that detachably supports the optical element 10. In FIG. 8, as an example, a case where a peeling protective layer 500 is provided between the light transmitting layer 100 and the support layer 400 and an adhesive layer 600 is provided on the back surface of the light transmitting reflective layer 200 is illustrated. .

  The peeling protection layer 500 plays a role of facilitating peeling of the support layer 400 when the transfer foil 30 is transferred to the transfer target. As a material of the peeling protection layer 500, for example, an acrylic resin, styrene, or nitrocellulose can be used. The peeling protective layer 500 can be formed by a known method such as a gravure coating method and a micro gravure coating method.

  The adhesive layer 600 includes, for example, a heat-sensitive adhesive that develops tackiness when heat is applied. As the heat-sensitive adhesive, for example, thermoplastic resins such as acrylic resin, vinyl chloride-vinyl acetate copolymer, epoxy resin, and ethylene-vinyl alcohol copolymer can be used. The adhesive layer 600 is obtained, for example, by applying the above-described resin onto the light transmission layer 100 using a coater such as a gravure coater, a micro gravure coater, or a roll coater.

  The transfer foil 30 is transferred to a transfer target by, for example, a roll transfer machine or a hot stamp. At this time, peeling occurs in the peeling protection layer 500, and the optical element 10 is attached to the transfer object via the adhesive layer 600.

  FIG. 9 is a plan view schematically showing an example of a labeled article in which an anti-counterfeiting or identification label is supported on the article. In FIG. 9, a printed matter 40 is depicted as an example of an article with a label.

  The printed matter 40 is a magnetic card and includes a base material 41. The base material 41 is made of plastic, for example. A printed layer 42 and a strip-shaped magnetic recording layer 43 are formed on the substrate 41. Furthermore, the optical element 10 is affixed to the base material 41 as a forgery prevention or identification label. The optical element 10 has the same structure as that described with reference to FIGS. 1 to 6 except that the displayed image is different.

  The printed matter 40 includes the optical element 10. Therefore, as described above, it is difficult to forge or imitate the printed material 40. In addition, since the printed matter 40 includes the optical element 10, it is easy to discriminate an article whose authenticity is unknown from a genuine article to a non-authentic article. Moreover, since the printed matter 40 further includes the printed layer 42 in addition to the optical element 10, it is easy to compare the appearance of the printed layer 42 with the appearance of the optical element. Therefore, compared with the case where the printed matter 40 does not include the print layer 42, it is easier to determine an article whose authenticity is unknown from the genuine product to the non-authentic product.

  In FIG. 9, a magnetic card is illustrated as a printed material including the optical element 10, but the printed material including the optical element 10 is not limited thereto. For example, the printed matter including the optical element 10 may be another card such as a wireless card, an IC (integrated circuit) card, or an ID (identification) card. Alternatively, the printed matter including the optical element 10 may be securities such as gift certificates and stock certificates. Alternatively, the printed matter including the optical element 10 may be a tag to be attached to an article to be confirmed to be genuine. Alternatively, the printed matter including the optical element 10 may be a package body that contains an article to be confirmed to be genuine or a part thereof.

  Moreover, in the printed matter 40 shown in FIG. 9, the optical element 10 is affixed to the base material 41, but the optical element 10 can be supported on the base material by other methods. For example, when paper is used as the substrate, the optical element 10 may be rolled into the paper and the paper may be opened at a position corresponding to the optical element 10.

  Moreover, the labeled article may not be a printed material. That is, the optical element 10 may be supported on an article that does not include a printed layer. For example, the optical element 10 may be supported by a luxury item such as a work of art.

  FIG. 10 is a schematic diagram illustrating an example of a determination device for determining an article whose authenticity is unknown between a genuine product and a non-authentic product. FIG. 11 is a schematic diagram illustrating another example of a determination device for determining an article whose authenticity is unknown between a genuine product and a non-authentic product.

  The determination device 50 includes a support base (not shown), a light source 51, a photodetector 52, a light shielding unit 53, and an output unit 54. In FIGS. 10 and 11, a discrimination target 60 including the optical element 10 is depicted as an article whose authenticity is to be discriminated.

  The support base plays a role of fixing the discrimination target 60 at a predetermined position. The support base may further include a mechanism for aligning the position of the optical element 10 of the discrimination target 60 and the irradiation position of the illumination light emitted from the light source 51. In this case, discrimination between genuine products and non-genuine products can be performed with higher accuracy.

  The support base may be omitted. For example, the discrimination device 50 may be a hand-held device that can discriminate between genuine products and non-genuine products by directly holding them over the discrimination object 60.

  The light source 51 plays a role of radiating illumination light to a portion of the discrimination target 60 where the optical element 10 should be provided if it is a genuine product. As the light source 51, for example, an LED (Light Emitting Diode) light source, a laser light source, a halogen lamp, or an HID (High Intensity Discharge) lamp can be used.

  However, if the wavelength dispersion of the illumination light emitted from the light source is large, the angle at which the diffracted light from the optical element 10 is emitted varies, and the discrimination accuracy may be reduced. Therefore, the illumination light emitted from the light source is preferably close to monochromatic light. Therefore, as the light source 51, an LED light source or a laser light source is typically used. Alternatively, the illumination light is monochromatic by using an optical filter or the like together.

  When monochromatic light is used as illumination light, diffracted light is emitted only in a specific emission angle and emission direction according to the wavelength λ. In this case, typically, the wavelength λ of the illumination light emitted from the light source 51 is set to be larger than the center distance d of the concave portion or the convex portion RP included in the optical element 10. This makes it possible to limit the emission angle β of the diffracted light emitted from the first interface IA to a negative value as described above with reference to FIG.

  The illumination light is preferably parallel light. Therefore, when the light from the light source 51 is a divergent light beam, it is desirable to use a lens and / or a mirror to make this light parallel light. In this way, since the illumination light can be emitted to the discrimination target 60 at a uniform angle, the exit angle and the exit direction of the diffracted light are also uniform, and the detection sensitivity can be improved.

  As shown in FIG. 11, a plurality of light sources may be used as the light source 51. In FIG. 11, as an example, the case where the light source 51 includes three types of light sources 51A to 51C is illustrated. In this case, for example, by using a light source capable of emitting illumination light having different wavelengths as the plurality of light sources, it is possible to emit a plurality of diffracted lights having different wavelengths, emission angles, and emission directions. Become. By detecting these, the authenticity of the discrimination target 60 can be discriminated with higher accuracy.

  The photodetector 52 has a role of detecting the diffracted light emitted from the optical element 10. That is, the light detector 52 plays a role of outputting information indicating whether or not the diffracted light is detected to the output unit 54 when the illumination light is emitted from the light source 51 to the discrimination target 60. Yes.

  The light shielding unit 53 plays a role of blocking light leakage between the light source 51 and the photodetector 52. By providing the light-shielding portion 53, noise in the photodetector 52 is reduced, and the accuracy of determining the authenticity of the discrimination target 60 is improved. The light shielding part 53 may be omitted.

  The output unit 54 plays a role of outputting discrimination information corresponding to the output of the photodetector 52. For example, when the light detector 52 does not detect the diffracted light from the optical element 10, the output unit 54 outputs discrimination information indicating that the discrimination target 60 is a non-genuine product. Alternatively, when the light detector 52 detects the diffracted light from the optical element 10, it outputs discrimination information indicating that the discrimination target 60 is a genuine product. This discrimination information is transmitted to the user, for example, visually, audibly, or by tactile sensation such as vibration.

  It should be noted that the inside of the discriminating apparatus 50 is preferably made difficult to be observed from the outside. This makes it difficult for a person who attempts forgery to obtain information such as the arrangement of the light source 51 and the detector 52, and can further improve the forgery prevention effect by the combination of the optical element 10 and the determination device 50.

  Hereinafter, an operation for determining authenticity by the determining device 50 will be described.

  First, the first measurement condition will be described.

  FIG. 12 is a schematic diagram showing a positional relationship in the traveling direction of light under the first measurement condition.

  Under this measurement condition, the illumination light emitted from the light source 51 is incident on the discrimination target 60 from a direction inclined with respect to the normal line N of the surface of the discrimination target 60.

  Here, a plane P1 defined by the light ray A and the normal line N of the illumination light is considered. In the plane P1, the angle range on the light ray A side with respect to the normal N is defined as a negative angle range. In this case, if the discrimination target 60 includes the optical element 10, the orthogonal projection D 'of the light beam D of the diffracted light onto the plane P1 is included in the negative angle range. Therefore, under this first measurement condition, the light detector 52 detects the diffracted light beam D emitted at a predetermined emission angle defined by the above equation (1) in the negative angle range.

  Under the first measurement condition, the output unit 54 performs, for example, the following operation.

  That is, when the light detector 52 does not detect light under this measurement condition, the output unit 54 outputs discrimination information indicating that the discrimination target 60 is a non-genuine product. On the other hand, when the photodetector 52 detects light under the same conditions, the output unit 54 outputs discrimination information indicating that the discrimination target 60 is a genuine product. Note that the output unit 54 may execute both of these two operations or only one of them.

  As described above, when the determination device 50 is used, it is possible to determine whether the determination target object 60 is a genuine product including the optical element 10 relatively easily and with high accuracy.

  Next, the second measurement condition will be described.

  FIG. 13 is a schematic diagram showing a positional relationship in the traveling direction of light under the second measurement condition. The second measurement condition is typically applied when the light detector 52 detects light in the first measurement condition.

  Even under this measurement condition, the illumination light emitted from the light source 51 is incident on the discrimination target 60 from a direction inclined with respect to the normal N of the surface of the discrimination target 60. However, the incident angle at which the illumination light is emitted may be different from that in the first measurement condition.

  Here, a plane P2 defined by the light beam B and the normal N of the illumination light under the second measurement condition is considered. In the plane P2, an angle range opposite to the angle range on the light ray B side with respect to the normal line N is defined as a positive angle range. In this case, if the discrimination target 60 includes the optical element 10, the orthogonal projection E ′ of the light beam E of the first-order diffracted light onto the plane P2 should not be included in the positive angle range. Therefore, under this second measurement condition, the light emitted in this positive angle range is detected by the photodetector 52.

  Under the second measurement condition, the output unit 54 performs, for example, the following operation.

  That is, when the light detector 52 detects light under this measurement condition, the output unit 54 outputs discrimination information indicating that the discrimination target 60 is a non-genuine product. On the other hand, when the light detector 52 does not detect light under the same conditions, the output unit 54 outputs discrimination information indicating that the discrimination target 60 is a genuine product. Note that the output unit 54 may execute both of these two operations or only one of them.

  By combining the first measurement condition and the second measurement condition, it is possible to determine whether the determination target object 60 is a genuine product or a non-genuine product with higher accuracy.

  The optical element 10 described above may be used for purposes other than prevention of forgery. For example, the optical element 10 can be used as a toy, a learning material, or a decoration.

1 is a plan view schematically showing an optical element according to one embodiment of the present invention. Sectional drawing along the II-II line of the optical element shown in FIG. The perspective view which expands and shows an example of the structure employable as the 1st interface part of the optical element shown in FIG.1 and FIG.2. The perspective view which expands and shows the other example of the structure employable as the 1st interface part of the optical element shown in FIG.1 and FIG.2. The figure which shows a mode that a 1st interface part inject | emits a diffracted light schematically. The top view which shows roughly an example of the optical element which comprised the display surface with the some pixel arranged in the matrix form. Sectional drawing which shows schematically the adhesive label which concerns on 1 aspect of this invention. Sectional drawing which shows schematically the transfer foil which concerns on 1 aspect of this invention. The top view which shows roughly an example of the labeled article formed by making an anti-counterfeiting or identification label supported by the article. Schematic which shows an example of the discrimination | determination apparatus for discriminating the articles | goods whose authenticity is unknown between a genuine article and a non-authentic article. Schematic which shows the other example of the discrimination | determination apparatus for discriminating the articles | goods whose authenticity is unknown between a genuine article and a non-authentic article. Schematic which shows the positional relationship of the advancing direction of the light in 1st measurement conditions. Schematic which shows the positional relationship of the advancing direction of the light in 2nd measurement conditions.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Optical element, 20 ... Adhesive label, 30 ... Transfer foil, 40 ... Printed matter, 41 ... Base material, 42 ... Print layer, 43 ... Magnetic recording layer, 50 ... Discrimination device, 51, 51A, 51B, 51C ... Light source, 52 ... Photodetector, 53 ... Light-shielding part, 54 ... Output part, 60 ... Discrimination object, 100 ... Light transmission layer, 200 ... Light-transmissive reflection layer, 300 ... Adhesive layer, 400 ... Support layer, 500 ... Peeling Protective layer, 600 ... adhesive layer, IA ... first interface part, IB ... second interface part, RP ... concave or convex part, L1 ... illumination light, L2 ... regular reflection light or 0th order diffracted light, L3 ... first order diffracted light.

Claims (8)

  A light-transmitting layer in which one principal surface includes an interface portion in which a plurality of concave or convex portions arranged one-dimensionally or two-dimensionally are provided at a center-to-center distance of 200 nm to 500 nm; and at least a part of the interface portion An optical element comprising a light-transmissive reflective layer having a single layer structure coated with   The optical element according to claim 1, wherein the light transmissive reflective layer is made of an inorganic material.   The interface portion is formed by arranging a plurality of pixels, and the plurality of pixels are two or more different in at least one of the shape, depth or height, distance between centers, and arrangement pattern of the plurality of recesses or projections. The optical element according to claim 1, further comprising:   An adhesive label comprising the optical element according to any one of claims 1 to 3 and an adhesive layer provided on the optical element.   A transfer foil comprising the optical element according to claim 1 and a support layer that releasably supports the optical element.   A labeled article comprising the optical element according to any one of claims 1 to 3 and an article supporting the optical element. A discrimination device for discriminating a discrimination object between a genuine product and a non-genuine product,
A light source that emits illumination light;
A photodetector;
An output unit that outputs discrimination information according to the output of the photodetector;
The output unit irradiates the illumination light from a first direction parallel to a first plane perpendicular to the surface of the discrimination target object and inclined with respect to a normal line of the surface, to the first plane. Is emitted from the discrimination target in a second direction in a negative angle range defined as an angle range on the first direction side with respect to the normal line in an angle range in the first plane. When the light detector does not detect light under the first measurement condition that the light detector detects, the information indicating that the object to be discriminated is a non-genuine product is output as the discrimination information And a second operation for outputting information indicating that the discrimination target is genuine as the discrimination information when the light detector detects light under the first measurement condition. A determination apparatus that executes at least one of the following.   The output unit is a case where the photodetector detects light under the first measurement condition, and is parallel to a second plane perpendicular to the surface and is normal to the surface. The illumination light is irradiated from a third direction inclined and the orthographic projection onto the second plane is opposite to the angular range on the third direction side with respect to the normal line in the angular range in the second plane. The light detector detects light under a second measurement condition in which the light detector detects light emitted from the discrimination target in a fourth direction within a positive angle range defined as an angle range of A third operation for outputting information indicating that the discrimination target is a non-genuine product as the discrimination information, and the light detector does not detect light under the second measurement condition. 4th operation which outputs the information which shows that the above-mentioned discrimination subject is genuine as the above-mentioned discrimination information Discriminating apparatus according to claim 7, characterized by further performing at least one of.

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