JP2012159589A - Display body and article with label - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a display body which exhibits high forgery prevention effect.SOLUTION: The display body has a first interface part comprising a plurality of sub-regions including a first relief structure comprising a plurality of projections or recesses arrayed regularly at center-to-center distances of 200 nm or more and 500 nm or less. The plurality of projections or recesses constitute a projection array or a recess array which is orderly arranged. The first relief structure displays an achromatic color which is black to charcoal gray when observed at right angles to the first interface part. The projection array or the recess array functions as what is called a diffraction grating, and the first relief structure can emit diffracted light under a certain observation condition. The display body has the plurality of sug-regions differing in extension direction of the projection array or the recess array, so that the diffracted light by the first relief structure can be emitted to a plurality of directions to widen an observation region of the diffracted light.

Description

  The present invention relates to an image display technique that can be used, for example, to prevent forgery.

  Generally, securities such as gift certificates and checks, cards such as credit cards, cash cards and ID cards, and certificates such as passports and licenses must be printed with ordinary printed materials to prevent counterfeiting. The display body which has a different visual effect is affixed. In recent years, the distribution of counterfeit goods has become a social problem for articles other than these. Therefore, the opportunity to apply the same forgery prevention technology to such articles is increasing.

  As a display body having a visual effect different from that of a normal printed material, a display body including a diffraction grating in which a plurality of grooves are arranged is known. For example, the display body can display an image that changes according to the observation condition, or can display a stereoscopic image. Further, the spectral color shining in rainbow colors expressed by the diffraction grating cannot be expressed by a normal printing technique. Therefore, a display body including a diffraction grating is widely used for articles that require anti-counterfeiting measures.

  For example, Patent Document 1 describes that a pattern is displayed by arranging a plurality of diffraction gratings having different groove length directions or lattice constants (that is, groove pitches). When the relative position of the observer or the light source with respect to the diffraction grating changes, the wavelength of the diffracted light that reaches the eyes of the observer changes. Therefore, when the above configuration is adopted, an image that changes to a rainbow color can be expressed.

  In a display body using a diffraction grating, a relief type diffraction grating formed with a plurality of grooves is generally used. The relief type diffraction grating is usually obtained by duplicating from an original plate manufactured using photolithography.

  In Patent Document 1, as a method for producing an original plate of a relief type diffraction grating, a flat substrate coated with a photosensitive resist on one main surface is placed on an XY stage, and the stage is moved under computer control. A method for pattern exposure of a photosensitive resist by irradiating the photosensitive resist with an electron beam is described. In addition, the master of the diffraction grating can be formed using two-beam interference.

  In the manufacture of a relief type diffraction grating, usually, an original plate is first formed by such a method, and a metal stamper is prepared therefrom by a method such as electroforming. Next, using this metal stamper as a matrix, a relief type diffraction grating is duplicated. That is, first, for example, a thermoplastic resin or a photocurable resin is applied on a thin transparent substrate in the form of a film or sheet made of polyethylene terephthalate (PET) or polycarbonate (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 metal stamper is peeled from the cured resin to obtain a replica of the relief type diffraction grating.

  Generally, this relief type diffraction grating is transparent. Therefore, usually, a reflective layer is formed on a resin layer provided with a relief structure by depositing a metal such as aluminum or a dielectric in a single layer or multiple layers by vapor deposition.

  Then, the display body obtained in this way is affixed on the base material which consists of paper or a plastic film through an adhesive layer or an adhesion layer, for example. As described above, a display body with anti-counterfeit measures is obtained.

  An original plate used for manufacturing a display including a relief type diffraction grating is difficult to manufacture. Further, the transfer of the relief structure from the metal stamper to the resin layer must be performed with high accuracy. That is, high technology is required for manufacturing a display body including a relief type diffraction grating.

  However, as a result of the use of display bodies including relief-type diffraction gratings in many articles that require anti-counterfeiting measures, this technology has become widely recognized, and along with this, the occurrence of counterfeit products tends to increase. is there. For this reason, it has become difficult to achieve a sufficient anti-counterfeit effect using a display body that is characterized only by exhibiting rainbow light by diffracted light.

US Pat. No. 5,058,992

  An object of the present invention is to provide a display body that exhibits a characteristic visual effect and achieves a sufficient anti-counterfeit effect.

  1st side surface of this patent is provided with the 1st interface part divided into several sub-regions arranged regularly, and each of these sub-regions is 200 nm or more and average center distance of 500 nm or less A first relief structure comprising a plurality of convex portions or concave portions regularly arranged at a plurality of convex portions, or a convex row formed by the plurality of convex portions or a concave row formed by the plurality of concave portions. It is a display body having the plurality of sub-regions in which the extension direction of the convex portion row or the concave portion row of the relief structure is different.

  According to a second aspect of the present patent document, the plurality of sub-regions in which the extension direction of the convex portion row or the concave portion row of the first relief structure is different is the absolute value of the azimuth difference in the extension direction of the convex row or the concave row. The display body according to claim 1, wherein the display elements are continuously arranged adjacent to each other within 10 °.

  3. The third aspect of the present invention is characterized in that the average center-to-center distance is different for each of the plurality of sub-regions in which the extending direction of the convex portion row or the concave portion row of the first relief structure is different. Or it is a display of 2 description.

  According to a fourth aspect of the present patent, the plurality of sub-regions having different extending directions of the convex or concave rows of the first relief structure are arranged in a checkered pattern or a striped pattern at intervals of 3 μm or more and 300 μm or less. 4. The display body according to claim 1, wherein the display body is disposed.

  According to a fifth aspect of the present patent document, when a portion corresponding to the first interface portion is observed under a condition in which diffracted light from the first relief structure can be perceived, a convex row or a concave row of the first relief structure. The display body according to claim 4, configured to display a multicolor image having a different color corresponding to the difference in the average center distance for each of the plurality of sub-regions having different extension directions.

  A sixth side surface of the present patent is a display body according to a fifth side surface including a plurality of sub-regions having a first relief structure in which the extending direction of the convex portion row or the concave portion row of the first relief structure differs by approximately 45 °.

  According to the seventh aspect of the present patent, the average height or average depth of the plurality of convex portions or concave portions is greater than the average center-to-center distance of the plurality of convex portions or concave portions. It is the display body which concerns on either of the side surfaces.

  The eighth aspect of the present invention is a labeled article comprising the display according to any one of the first to seventh aspects and an article that supports the display.

  According to the present invention, a display body showing a characteristic visual effect is provided.

In the display according to the first aspect, each sub-region includes a first relief structure including a plurality of convex portions or concave portions regularly arranged with an average center distance of 200 nm or more and 500 nm or less. Therefore, when observed from the normal direction of the first interface portion, the reflectance is small regardless of the illumination conditions, and no diffracted light is emitted or viewed in the direction perpendicular to the first interface portion. Only short-wavelength light with low sensitivity is emitted as diffracted light. Therefore, the first relief structure displays a black to dark gray achromatic color when observed perpendicular to the first interface. Further, the plurality of convex portions or concave portions are regularly arranged to form a convex portion row or a concave portion row. The convex row or the concave row functions as a so-called diffraction grating, and the first relief structure can emit diffracted light under certain observation conditions. Since the display body has a plurality of sub-regions having different extension directions of the convex row or the concave row, the diffracted light by the first relief structure can be emitted in a plurality of directions, thereby widening the observation region of the diffracted light. be able to.
As described above, the display body according to the first side surface has a characteristic visual effect, and the diffracted light can be easily visually recognized compared to the display body in which the protrusion portion or the recess portion has a single extension direction. The catching effect (the eye-catching effect) is high, and authenticity determination can be easily performed.

  In the display according to the second aspect, the plurality of sub-regions in which the extension direction of the convex portion row or the concave portion row of the first relief structure is different has an absolute value of the azimuth difference in the extension direction of the convex portion row or the concave row. Contiguously arranged within °. Therefore, by observing this display body from the direction in which the diffracted light emitted from one of the sub-regions can be observed, and gradually changing the relative positional relationship between the illumination light and the display body and the observer, The sub-region where the diffracted light reaches the observer moves to the adjacent sub-region, and a visual effect as if the bright line by the diffracted light is moving can be exhibited. As a result, it is possible to display a color rich in movement by diffracted light.

  In the display according to the third aspect, the average distance between the centers of the convex portions or the concave portions is different for each of the plurality of sub-regions in which the extending directions of the convex portion rows or the concave portion rows of the first relief structure are different. For this reason, the wavelength of the diffracted light reaching the observer changes with respect to a fixed point where the diffracted light can be visually recognized according to the average center-to-center distance between the convex portions or the concave portions, and different colors can be displayed.

  In the display body according to the fourth aspect, a plurality of sub-regions having different extension directions of the first relief structure convex portion rows or concave portion rows are arranged in a checkered pattern or a stripe shape at intervals of 3 μm or more and 300 μm or less ( It is arranged in a band shape. It is difficult or impossible to distinguish between the sub-regions arranged at intervals of 3 μm or more and 300 μm or less when observed with the naked eye. For this reason, the sub-regions having the first relief structure in which the extending direction of the convex portion row or the concave portion row is different are arranged at such intervals, so that diffracted light can be emitted from any region on the display body in multiple directions. It is possible to inject. The observer can easily confirm the diffracted light without being conscious of the azimuth angle of the display body, and can easily determine the authenticity.

In the display body according to the fifth aspect, the sub-regions having the first relief structure in which the extending direction of the convex portion rows or the concave portion rows are different from each other at intervals of 3 μm or more and 300 μm or less are checkered or striped ) When the portion corresponding to the first interface portion is observed under the condition where the diffracted light from the first relief structure is visible, the extending direction of the convex row or the concave row For each of the sub-regions having different first relief structures, multi-color images having different colors corresponding to the difference in the average center-to-center distance are displayed.
The sub-region where the diffracted light reaching the observer is emitted by the sub-region having the first relief structure in which the extending direction of the convex portion row or the concave portion row is different varies depending on the illumination condition and the position of the observer and the display body. Therefore, for each sub-region having the first relief structure in which the direction of extension of the convex portion row or the concave portion row is different, a convex portion or a concave portion having a different average center-to-center distance is displayed so as to display a multicolor image. Accordingly, it is possible to realize a display body that can display different images depending on the situation. That is, this display body shows a characteristic visual effect. Further, it is more difficult to forge a display body that displays a multicolor image.

  The display body according to the sixth side surface is the display body according to the fifth side surface, and includes a sub-region having a first relief structure in which the extending direction of the convex portion row or the concave portion row differs by approximately 45 °. Since the extending direction of the convex portion row or the concave portion row is approximately 45 ° different, the emission direction of the diffracted light emitted from each sub-region can be furthest away, and the average center represented by each sub-region is between One image is visually recognized at a certain fixed point, and other images are visually recognized at a certain fixed point, without displaying a mixture of multi-color images due to convex portions or concave portions having different distances, and one image is clearly perceived. It becomes possible to do.

  In the display according to the seventh aspect, in each sub-region, the average center distance is in the range of 200 to 500 nm, and the average height or average depth of the protrusions or recesses is compared with the average center distance. Greater than. Such a display body enables black display with lower brightness with respect to the normal direction of the first interface portion.

  The labeled article according to the eighth aspect includes the display according to any one of the first to seventh aspects and an article that supports the display. Therefore, this labeled article exhibits a characteristic visual effect derived from the display body. This visual effect is useful, for example, in suppressing counterfeiting and unauthorized use of the article. This visual effect can also provide an aesthetic appearance to the article.

The top view which shows schematically the display body which concerns on 1 aspect of this invention. Sectional drawing along the II-II line of the display body of FIG. The perspective view which shows an example of the structure employable as the 1st relief structure of the display body shown in FIG. 1 thru | or FIG. FIG. 4 is a plan view of the structure of FIG. 3. The perspective view which shows an example of another structure employable as the 1st relief structure of the display body shown in FIG. 1 thru | or FIG. The top view of the structure of FIG. The figure which shows a mode that the diffraction grating which has a big grating constant inject | emits + 1st-order diffracted light. The figure which shows a mode that the diffraction grating which has a small grating constant inject | emits + 1st-order diffracted light. The top view which shows roughly the modification of the display body shown in FIG. 1 thru | or FIG. The top view which shows roughly the display body which concerns on another modification. The top view which shows an example of a labeled article schematically. Sectional drawing along the XII-XII line of the labeled article shown in FIG.

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

FIG. 1 is a plan view schematically showing a display body according to one aspect of the present invention. 2 is a cross-sectional view taken along the line II-II of the display body of FIG.
1 and 2, the X1 direction and the Y1 direction are parallel to the display surface of the display body 1 and intersect each other. The Z1 direction is a direction perpendicular to the X1 direction and the Y1 direction. Here, as an example, it is assumed that the X1 direction and the Y1 direction are orthogonal to each other.

  As shown in FIG. 2, the display body 1 includes a laminated body of a light transmission layer 11 and a reflection layer 12. Here, the light transmission layer 11 side is the front side, and the reflection layer 12 side is the back side. The light transmission layer 11 side may be the back side, and the reflection layer 12 side may be the front side.

The light transmission layer 11 is a layer having a light transmission property. The light transmission layer 11 is typically made of a transparent material.
The light transmissive layer 11 includes a light transmissive substrate 111 and a light transmissive resin layer 112. The light transmissive substrate 111 and the light transmissive resin layer 112 form a laminate. The light transmission layer 11 may have a single layer structure. Alternatively, the light transmission layer 11 may have a multilayer structure of three or more layers.

  The light transmissive substrate 111 is a film or sheet that can be handled by itself. As a material of the light transmissive substrate 111, for example, a resin having light transmissive properties such as polycarbonate and polyester can be used. The light transmissive substrate 111 can be omitted.

The light transmissive resin layer 112 is a layer formed on the light transmissive substrate 111. In this example, the surface of the light transmissive resin layer 112 serves as a reflecting surface. A relief structure is provided on the reflecting surface. These relief structures will be described in detail later.
The light transmissive resin layer 112 is obtained, for example, by applying a resin onto the light transmissive substrate 111 and curing the resin while pressing a stamper against the coating film. As the resin, for example, a thermoplastic resin, a thermosetting resin, or a photocurable resin can be used.

The reflective layer 12 covers the main surface on which the relief structure of the light transmissive resin layer 112 is provided. The reflective layer 12 may cover only a part of the main surface on which the relief structure of the light transmissive resin layer 112 is provided, or may cover the entire main surface.
As the reflective layer 12, for example, a metal layer made of a metal material such as aluminum, silver, gold, and alloys thereof can be used. Alternatively, a dielectric layer having a refractive index different from that of the light transmission layer 11 may be used as the reflective layer 12. Alternatively, as the reflective layer 12, a laminate of dielectric layers having different refractive indexes between adjacent ones, that is, a dielectric multilayer film may be used. The refractive index of the dielectric layer included in the dielectric multilayer film that is in contact with the light transmission layer 11 is preferably different from the refractive index of the light transmission layer 11. Examples of the material used for the dielectric multilayer film include zinc sulfide, titanium dioxide, and tantalum oxide as high refractive index materials, and silicon dioxide and magnesium fluoride as low refractive index materials.

  The reflective layer 12 can be formed by, for example, a vapor deposition method such as a vacuum evaporation method or a sputtering method. The reflection layer 12 that is entirely or partially covered with one main surface of the light transmissive resin layer 112 is formed by, for example, forming a thin film by a vapor deposition method and dissolving a part thereof in a chemical or the like, or The thin film can be obtained by peeling off a part of the thin film with an adhesive material that exhibits an adhesive strength stronger than that of the thin film and the light-transmitting resin layer 112 with respect to the previous thin film. The reflective layer 12 partially covering one main surface of the light transmissive resin layer 112 can also be formed by a vapor deposition method using a mask.

  One of the light transmission layer 11 and the reflection layer 12 can be omitted. However, when the display body 1 includes both the light transmission layer 11 and the reflection layer 12, compared with the case where only one of them is included, the previous interface is less likely to be damaged, and the visibility is superior. An image can be displayed.

  The display body 1 can further include other layers such as an adhesive layer, an adhesive layer, and a resin layer.

  For example, the adhesive layer or the adhesive layer is provided so as to cover the reflective layer 12. When the display body 1 includes both the light transmission layer 11 and the reflection layer 12, the shape of the surface of the reflection layer 12 is usually almost equal to the shape of the interface between the light transmission layer 11 and the reflection layer 12. When the adhesive layer or the adhesive layer is provided, it is possible to prevent the surface of the reflective layer 12 from being exposed. Therefore, it is difficult to duplicate the relief structure for the purpose of counterfeiting.

  When the light transmission layer 11 side is the back side and the reflection layer 12 side is the front side, the adhesive layer or the adhesive layer is formed on the light transmission layer 11, for example. When the main surface opposite to the light transmission layer 11 of the reflection layer 12 is used as the reflection surface, a light shielding layer is provided on the back side of the reflection layer 12 in addition to the light transmission layer 11 or instead of the light transmission layer 11. May be installed.

  For example, the resin layer is provided on the front side with respect to the laminated body of the light transmission layer 11 and the reflection layer 12. For example, in the case where the light transmission layer 11 side is the back side and the reflection layer 12 side is the front side, if the reflection layer 12 is covered with a resin layer, damage to the reflection layer 12 can be suppressed, and for the purpose of counterfeiting Reproduction of the relief structure can be made difficult. The resin layer is, for example, a hard coat layer that prevents the display surface from being scratched during use, an antifouling layer that suppresses the adhesion of dirt, and prevents reflection of light on the substrate surface Antireflection layer, antistatic layer and the like.

  The display body 1 is, for example, in front of the reflective layer 12, on the main surface of the light transmissive layer 11 on the viewer side, between the light transmissive substrate 111 and the light transmissive resin layer 112, or the light transmissive resin layer. A printed layer may be further included between the 112 and the reflective layer 12. When the print layer is provided, a complicated image can be displayed on the display body 1, and in addition, the information displayed on the display body 1 can be easily added.

  Next, the relief structure provided on the reflecting surface will be described.

  As described above, the interface between the light transmission layer 11 and the reflection layer 12 is a reflection surface. This reflecting surface includes the first interface portion 10 shown in FIG. The first interface portion 10 is a continuous region. The previous reflecting surface includes only one first interface portion 10 in the example illustrated in FIG. 1, but may include a plurality of first interface portions 10.

  The first interface portion 10 is partitioned into a plurality of regularly arranged sub-regions SA. Here, the sub-regions SA are arranged in the X1 direction and the Y1 direction, and form a square lattice-like arrangement structure. The subregion SA may form another arrangement structure. For example, the sub-region SA may form an array structure such as a rectangular lattice shape, a triangular lattice shape, or a combination thereof. By adopting a plurality of arrangement structures in the display body, the arrangement structure of all areas must be accurately reproduced, so that the forgery prevention effect can be further improved.

Typically, the sub-region SA is a virtual region, and the display body 1 does not include a structure corresponding to the rectangle shown by the solid line in FIG.
Each sub-region SA includes any one of the first relief structures DS1 to DS5 including a plurality of convex portions or concave portions. Further, each sub-region SA may be filled with the first relief structure, or may have a flat surface with no structure.

  In the example shown in FIG. 1, the sub-region SA has a square shape, and each of the relief structures DS1 to DS5 is filled in the sub-region SA. Each of the relief structures DS1 to DS5 may be arranged in another shape when viewed from the normal direction of the display body 1, that is, the Z1 direction. For example, each of the relief structures DS1 to DS5 may be formed in a circular region when viewed from the Z1 direction, or formed in a polygonal shape other than a square shape, for example, a triangular or quadrangular region. May be.

  Each of the relief structures DS1 to DS5 usually has a small dimension. For example, when the relief structures DS1 to DS5 are observed with the naked eye, it is impossible or difficult to distinguish one of the relief structures from the adjacent relief structure. Typically, each of the relief structures DS1 to DS5 has a maximum length in the range of 3 μm to 300 μm when viewed from the Z1 direction. When the maximum length is 300 μm or less, it is possible to prevent the observer from recognizing the shapes of the relief structures DS1 to DS5 when the display body 1 is observed with the naked eye. When the maximum length is 3 μm or less, it is difficult to form convex portions or concave portions described later with sufficiently high density and shape accuracy. When the maximum length is 300 μm or more, it is impossible to prevent the observer from recognizing the shapes of the relief structures DS1 to DS5 when the display body 1 is observed with the naked eye.

  Each of the relief structures DS1 to DS5 includes a plurality of convex portions or concave portions. That is, a plurality of convex portions or concave portions are provided on the surface of the reflective layer 12 on the viewer side. Here, as shown in FIG. 3, each of the relief structures DS1 to DS5 includes a plurality of convex portions. Note that the items described below with respect to the convex portions also apply to the concave portions except that “height” and “convex row” described with respect to the convex portions should be read as “depth” and “concave row” with respect to the concave portions. It is the same.

  FIG. 3 is a perspective view showing an example of a relief structure that can be employed in the display body shown in FIGS. FIG. 4 is a plan view of the relief structure shown in FIG. FIG. 3 illustrates the first relief structure as viewed from the light transmission layer 11 side. The dotted lines shown in FIG. 3 to FIG. 4 indicate a convex part row composed of a plurality of convex parts. That is, the extension direction of the convex portion row of the relief structure shown in FIGS. 3 to 4 coincides with the directions of the X1 axis and the Y1 axis.

  FIG. 5 is a perspective view showing another example of a relief structure that can be employed in the display body shown in FIGS. 6 is a plan view of the relief structure shown in FIG. FIG. 5 also shows the first relief structure as viewed from the light transmission layer 11 side. The relief structure shown in FIGS. 5 and 6 is different from the relief structure shown in FIGS. 3 and 4 in the extending direction of the projections. The extension direction of the convex portion row of the relief structure shown in FIGS. 5 and 6 is parallel to a straight line that intersects the X1 axis and the Y1 axis at 45 °.

  The first relief structures DS1 to DS5 described with reference to FIGS. 1 and 2 are, for example, the relief structures DS shown in FIGS. 3 and 4 or FIGS. The relief structure DS includes a plurality of convex portions PR regularly arranged with an average center distance AD of 200 nm or more and 500 nm or less. The convex part PR may form a convex part row extending in an orientation other than the orientations shown in FIGS. 3 and 4 or FIGS. 5 and 6.

  Each convex part PR typically has a tapered shape. The tapered shape is, for example, a semi-spindle shape, a cone shape such as a cone and a pyramid, or a truncated cone shape such as a truncated cone and a truncated pyramid. The side surface of the convex part PR may be composed only of an inclined surface or may be stepped. The taper shape is useful for reducing the reflectance of light incident on the relief structure DS, as will be described later. Note that when the light transmissive resin layer 112 is formed using a stamper, the tapered shape facilitates removal of the cured light transmissive resin layer 112 from the stamper and contributes to an improvement in productivity. A part of the convex part PR may not have a tapered shape.

  As described above, the protrusions PR are regularly arranged. Therefore, the relief structure DS can function as a diffraction grating. Specifically, the relief structure DS shown in FIG. 3 and FIG. 4 or FIG. 5 and FIG. 6 functions in substantially the same manner as a diffraction grating in which grooves are arranged as indicated by dotted lines.

  However, the highly diffracted light emitted from the relief structure DS can only be observed under special conditions. This will be described below.

  As described above, the first relief structure DS functions as a diffraction grating. When the diffraction grating is illuminated, the diffraction grating emits strong diffracted light in a specific direction with respect to the traveling direction of the illumination light that is incident light.

The exit angle β of the m-order diffracted light (m = 0, ± 1, ± 2,...) is expressed by the following equation (1) when the light travels in a plane perpendicular to the length direction of the diffraction grating groove. It can be calculated from

d = mλ / (sin α−sin β) (1)

In Expression (1), d represents the grating constant of the diffraction grating, m represents the diffraction order, 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. In other words, the absolute value of α is equal to the incident angle of the illumination light, and in the case of a reflective diffraction grating, the incident direction of the illumination light and the emission direction of the specularly reflected light are the method of the interface where the diffraction grating is provided. Symmetric with respect to the line.

  When the diffraction grating is a reflection type, the angle α is 0 ° or more and less than 90 °. In addition, when illumination light is irradiated to the interface provided with the diffraction grating from an oblique direction, and the angle in the normal direction, that is, two angle ranges having a boundary value of 0 °, the angle β is determined as follows. A positive value is obtained when the exit direction and the exit direction of the specularly reflected light are within the same angular range, and a negative value when the exit direction of the diffracted light and the incident direction of the illumination light are within the same angular range. Hereinafter, an angle range including the emission direction of the specularly reflected light is referred to as a “positive angle range”, and an angle range including the incident direction of the illumination light is referred to as a “negative angle range”.

  When the diffraction grating is observed from the normal direction, the diffracted light contributing to the display is only diffracted light having an exit angle β of 0 °. Therefore, in this case, if the lattice constant d is larger than the wavelength λ, there exists a wavelength λ and an incident angle α satisfying the relationship shown in the above equation (1). That is, in this case, the observer can observe diffracted light having a wavelength λ that satisfies the relationship shown in the above equation (1).

  On the other hand, when the lattice constant d is smaller than the wavelength λ, there is no incident angle α that satisfies the relationship shown in the equation (1). Therefore, in this case, the observer cannot observe the diffracted light.

  As is clear from this description, the relief structure DS having a small average center distance AD of the protrusions PR does not emit diffracted light in the normal direction unlike a normal diffraction grating. Alternatively, the diffracted light emitted from the relief structure DS in the normal direction has only low visibility. That is, a black or dark gray achromatic color is observed by the observer.

This will be described in more detail with reference to the drawings.
FIG. 7 is a diagram schematically showing how a general diffraction grating emits first-order diffracted light. FIG. 8 is a diagram schematically showing a state in which a diffraction grating having a small lattice constant emits first-order diffracted light.

7 and 8, IF indicates the interface on which the diffraction grating GR is formed, and NL indicates the normal line of the interface IF. IL indicates white illumination light composed of light of a plurality of wavelengths, and RL indicates specular reflection light or zero-order diffracted light. DLr, DLg, and DLb indicate first-order diffracted light having wavelengths corresponding to red, green, and blue, respectively, obtained by spectrally dividing the white illumination light IL.
The interface IF shown in FIG. 7 is provided with a diffraction grating GR having a grating constant larger than the shortest wavelength of visible light, for example, 400 nm. On the other hand, the interface IF shown in FIG. 8 is provided with a diffraction grating GR whose lattice constant is smaller than the shortest wavelength of visible light.

  As apparent from the equation (1), when the grating constant d of the diffraction grating is larger than the shortest wavelength of visible light, for example, larger than 400 nm, the illumination light IL is irradiated from an oblique direction to the interface IF. Then, as shown in FIG. 7, the diffraction grating emits the first-order diffracted beams DLr, DLg, and DLb at the emission angles βr, βg, and βb within the positive angle range, respectively. Although not shown, this diffraction grating emits first-order diffracted light in the same manner for light of other wavelengths.

  On the other hand, when the grating constant d of the diffraction grating is larger than ½ of the shortest wavelength of visible light and less than the shortest wavelength of visible light, when the illumination light IL is irradiated from an oblique direction to the interface IF, As shown in FIG. 8, the diffraction grating emits the first-order diffracted beams DLr, DLg, and DLb at the emission angles βr, βg, and βb within the negative angle range, respectively. For example, considering the case where the angle α is 50 ° and the grating constant d is 330 nm, the diffraction grating diffracts light having a wavelength λ of 540 nm (green) in the white illumination light IL, and converts the first-order diffracted light DLg. Injection is performed at an injection angle βg of about −60 °.

  As is clear from this explanation, the relief structure DS emits diffracted light only in the negative angle range without emitting diffracted light in the positive angle range. Alternatively, the relief structure DS emits only diffracted light with low visibility within a positive angle range, and emits diffracted light with high visibility within a negative angle range. That is, unlike the normal diffraction grating, the relief structure DS emits diffracted light with high visibility only within a negative angle range.

  In general, when observing an article, particularly when observing a light-absorbing article having a small light reflection ability and light scattering ability, the article and the light source are relative to the observer's eyes so that regular reflection light can be perceived. Align. Therefore, when the configuration described with reference to FIG. 7 is adopted in each of the relief structures DS1 to DS5, the observer perceives diffracted light with a relatively high probability even if the observer does not know the fact itself. On the other hand, when the configuration described with reference to FIG. 8 is adopted in each of the relief structures DS1 to DS5, an observer who does not know the fact cannot perceive diffracted light in many cases. Therefore, it is difficult for the display 1 to realize that the first interface portion can emit diffracted light.

  Further, as described above, the convex part PR typically has a tapered shape. When such a structure is adopted, if the average center-center distance AD is sufficiently short, the relief structure DS can be regarded as having a refractive index that continuously changes in the Z1 direction. Therefore, the reflectance for the regular reflection light of the relief structure DS is small no matter what angle is observed.

  As described above, the relief structure DS does not substantially emit diffracted light to the front surface (normal direction) of the display body.

  Therefore, for example, a portion corresponding to the relief structure DS in the display body 1 displays, for example, black to dark gray when observed from the normal direction. Note that “black” means that, for example, when the portion of the display body 1 corresponding to the relief structure DS is irradiated with light from the normal direction and the intensity of specular reflection light is measured, the wavelength is within a range of 400 nm to 700 nm. This means that the reflectance is 10% or less for all the light components. Here, “dark gray” means that, for example, when the portion of the display body 1 corresponding to the relief structure DS is irradiated with light from the normal direction and the intensity of specular reflection light is measured, the wavelength is visible light. This means that the reflectance is about 25% or less for all the light components in the range of 400 nm to 700 nm which is the wavelength of.

  Thus, the relief structure DS displays, for example, black to dark gray when observed from the front. Accordingly, the portion of the display body 1 corresponding to the first interface portion 10 looks like, for example, a black or dark gray print layer when observed from the front.

  As described above, the relief structure DS displays, for example, black to dark gray when observed from the front. The relief structure DS displays a chromatic color derived from diffraction when the observation angle is within a negative angle range.

  The average center-to-center distance of the relief structure is 500 nm or less, and is preferably less than the shortest wavelength of visible light, for example, 400 nm or less. Furthermore, a structure that has a function of emitting the first-order diffracted light by being set to 1/2 or more of the shortest wavelength of visible light, that is, 200 nm or more and 400 nm or less, and looks like a black or dark gray printed layer is obtained. When the average center-center distance is set to less than 200 nm, a structure that looks like a black or dark gray printed layer can be obtained, but the function of emitting the first-order diffracted light cannot be obtained.

  In general, as the average center distance decreases, the brightness and saturation decrease, enabling a blacker display, and as the average center distance increases, the brightness increases slightly and dark gray It becomes a structure perceived by.

  In addition, as the height of the convex portion is larger, a black display is possible, and as the height is reduced, the luminance is increased and perceived as dark gray. Typically, it is desirable that the height of the convex portion be 1/2 or more of the average center distance. Specifically, for example, when the average center distance is 500 nm, dark gray can be displayed by setting the height to 250 nm or more, and further, the height is 500 nm or more which is larger than the average center distance. This enables a blacker display. If the structure is much higher than the average center-to-center distance, sufficient blackness can be obtained, and more accurate manufacturing technology is required, so that the forgery prevention effect can be further improved. About the height of the convex part, it may take a different value for each convex part, and may be formed with a uniform height, but it is observed that it is formed with a uniform height. In particular, unevenness due to slight fluctuations in blackness due to unevenness in the height of the projections is less likely to occur, which is desirable.

Next, the visual effect by the display body 1 shown in FIG. 1 is demonstrated.
In the display body 1 shown in FIG. 1, the first relief structures DS1 to DS5, each having a different extension direction of the convex row, are regularly arranged in stripes in parallel with the Y1 axis. The plurality of convex portions formed in the first relief structures DS1 to DS5 are all arranged with an average center distance of 200 nm or more and 500 nm or less. Therefore, when the display body 1 is observed from the vertical direction, the first interface portion 10 looks black or dark gray.

  On the other hand, since the extending directions of the convex rows are different in the first relief structures DS1 to DS5, the directions in which the diffracted light is emitted are also different. Since the diffracted light emitted by the first relief structure DS1 is emitted in directions parallel to the X1 axis and the Y1 axis based on the extending direction of the convex row, it is from a point on the X1 axis to the Y1 axis. Although the diffracted light can be seen by observing the display body 1, since the diffracted light from the other relief structures DS2 to DS4 is emitted in different directions, an observer on the X1 axis to the Y1 axis observes the diffracted light. Can not do it. Similarly, the diffracted light from the relief structures DS1 and DS3 to DS5 cannot be observed from the direction in which the diffracted light from the relief structure DS2 can be observed.

  As described above, the diffracted light reaching the fixed point can be selectively controlled by changing the direction of the convex row formed in the first relief structure.

  FIG. 9 shows an example of the display body 1 constituted by the first relief structures DS1 and DS2 in which the extending directions of the convex portion rows are different from each other. The structure formed in the first relief structure DS1 is, for example, that shown in FIGS. 3 to 4, in which the convex portions are arranged in a direction parallel to the X1 axis and the Y1 axis, and the convex row is also the X1 axis. Parallel to the Y1 axis. In addition, the structure formed in the first relief structure DS2 is, for example, as shown in FIGS. 5 to 6, and the convex portions are arranged in a direction different from the X1 axis and the Y1 axis, and the convex row is also X1. It extends in a direction different from the axis and the Y1 axis. In FIG. 9, the description of the extending directions of the protrusions and the protrusion rows formed in the first relief structures DS1 to DS2 is omitted.

  When the display body 1 is observed from the normal direction of the display body, the first interface portion 10 looks like a black or dark gray printed layer. Further, when the display body is observed under the condition where the diffracted light from the first relief structure DS1 is observed (for example, a fixed point on the X1 axis), the alphabet “A” appears to shine on the display body 1 due to the diffracted light. Further, when the display body is observed under the condition in which the diffracted light from the first relief structure DS2 is observed, the portion around the alphabet “A” appears to be lit by the diffracted light.

  In this way, by changing the extension direction of the convex portion row formed of a plurality of convex portions formed inside the first relief structure, the emission direction of the diffracted light can be changed, and the diffracted light can be observed. The possible observation area can be increased.

  In addition, in the first interface portion composed only of the first relief structure in which the extending direction of the convex row composed of a plurality of convex portions is the same, the direction in which the diffracted light can be observed is limited. By arranging a plurality of substructures having different extension directions, a display body in which diffracted light can be visually recognized at various angles can be realized.

  In addition, when the plurality of sub-regions having the first relief structure having different extension directions of the convex portion rows are continuously arranged adjacent to each other with an absolute value of a difference in azimuth angle in the extension direction of the convex row within 10 °. Observe the display body from the direction in which the diffracted light emitted from one of the sub-regions can be observed, and gradually change the illumination light and the relative positional relationship between the display body and the observer. The sub-region where the diffracted light reaches the person moves to the adjacent sub-region, and a visual effect as if the bright line by the diffracted light is moving can be exhibited. As a result, it is possible to display a color rich in movement by diffracted light.

  The smaller the difference in the azimuth angle in the extension direction of the convex row, the smoother the diffracted light can be observed. The difference in the azimuth angle in the direction of extension of the convex row increases, and for example, under general observation conditions in which a display body in which sub-regions having a size of 100 μm are regularly arranged is visually observed from a distance of 30 cm. When the absolute value of the difference in azimuth in the extension direction of the partial row exceeds 10 °, the diffracted light reaches the observer from a certain sub-region, and from there, the relative relationship between the illumination light source or the display and the observer While the positional relationship gradually changes and the diffracted light from another sub-region where the absolute value of the azimuth difference in the extension direction of the convex row adjacent to the sub-region exceeds 10 ° reaches the observer, A situation in which the diffracted light does not reach the observer occurs, the display of the continuous bright line of the diffracted light by the plurality of sub-regions is interrupted, and it is difficult to realize a visual effect in which the bright line moves smoothly. FIG. 1 shows a display body 1 composed of a plurality of sub-regions including relief structures DS1 to DS5 in which the extending directions of the convex portion rows are gradually different.

  By differentiating the average center-to-center distance of the convex portions formed in each sub-region having the first relief structure in which the extending direction of the convex portion rows is different, the relative relationship between the illumination light source and the display body and the observer can be changed. Based on the positional relationship, the sub-region that emits the observable diffracted light changes, and the wavelength of the diffracted light that reaches the observer at that time also changes, allowing the observer to perceive different colors. Thereby, a display rich in color by diffracted light is possible, and the eye catching effect can be improved. Even with the first relief structure having such a configuration, black or dark gray is uniformly observed when observed from the vertical direction of the display body.

  FIG. 10 shows an example of a display body in which a plurality of sub-regions having the first relief structure with different extending directions of the convex row are arranged in a checkered pattern. In FIG. 10, two types of first relief structures DS1 and DS2 having different extending directions of the convex row are arranged adjacent to each other. Here, the first relief structures DS1 to DS2 typically have a maximum length in the range of 300 μm or less when observed from the Z1 direction. When the maximum length is 300 μm or less, it is possible to prevent the viewer from recognizing the shapes of the relief structures DS1 to DS2 when the display body 1 is observed with the naked eye.

  When the display body having such a configuration is observed under conditions in which diffracted light from the relief structure DS1 can reach, it is perceived that the entire surface of the display body 1 is shining. However, the amount of diffracted light is approximately halved corresponding to the proportion of the area of the relief structure DS1 in the display body 1. Further, when this display body is observed under a condition where the diffracted light from the relief structure DS2 can reach, it is similarly perceived that the entire surface of the display body 1 is shining. That is, by using the display body having such a configuration, it is possible to widen an observation area where diffracted light can be observed. It becomes possible to observe the diffracted light in a larger number of observation areas by setting a larger number of types in the extending direction of the convex row.

  Here, by controlling the average center-to-center distance of the protrusions so that different images can be displayed depending on the difference in the wavelength of the diffracted light, for each sub-region consisting of a relief structure in which the extension direction of the protrusions is different, As the viewing direction and illumination angle with respect to the display body 1 gradually change, different images can be viewed. A display body in which an image changes in accordance with a change in observation direction or illumination angle has a high eye catching effect, and at the same time, it is extremely difficult to accurately forge all display images, and a high forgery prevention effect can be realized.

  When realizing a display body capable of displaying different images by diffracted light for each sub-region having a relief structure in which the extension direction of the convex part row is different, the first relief in which the extension direction of the convex part row is different by about 45 ° It is more preferable that the sub-regions having the structure are arranged in a checkered pattern or a stripe pattern since visibility is further improved when a display image is displayed. By arranging the sub-regions having different extension directions of the convex row in a checkered or striped manner, the area occupied by each region can be made one-to-one, so that the amount of diffracted light constituting each display image can be reduced. Can be even. A typical arrangement example of convex portions that can be adopted as the first relief structure of this patent is a configuration in which squares are arranged as shown in FIGS. 3 and 5, and in this case, the convex row is, for example, as shown in FIG. It extends in two directions parallel to the X1 axis and the Y1 axis. For this reason, by arranging the sub-regions having the first relief structures that differ by approximately 45 °, the emission directions of the diffracted lights can be most distant from each other in the sub-regions in which the extension direction of the convex row is different. Thereby, it is possible to prevent the display image from being deteriorated such that the respective display images are mixed and the visibility is lowered, and to display each image clearly and separately.

Next, an example of how to use the display body 1 will be described.
The display body 1 described above can be affixed as a label to a printed material or an article outside the printed material through an adhesive material or the like for the purpose of preventing counterfeiting, for example. As described above, the display body 1 is difficult to counterfeit or imitate itself. Therefore, when this label is supported on an article, it is difficult to counterfeit or imitate the genuine article with label.
FIG. 11 is a plan view schematically showing an example of a labeled article. 12 is a cross-sectional view taken along line XII-XII of the labeled article shown in FIG.

In FIGS. 11 and 12, a printed matter 100 is depicted as an example of a labeled article. The printed material 100 is an IC (integrated circuit) card and includes a base material 60. The substrate 60 is made of plastic, for example. A concave portion is provided on one main surface of the substrate 60, and the IC chip 50 is fitted in the concave portion. Electrodes are provided on the surface of the IC chip 50, and information can be written into the IC and information recorded in the IC can be read through these electrodes. A printed layer 40 is formed on the substrate 60. The display body 1 mentioned above is being fixed to the surface in which the printing layer 40 of the base material 60 was formed through the adhesion layer, for example. For example, the display body 1 is prepared as an adhesive sticker or a transfer foil, and is fixed to the substrate 60 by sticking the display body 1 to the printing layer 40.
The printed material 100 includes the display body 1. Therefore, forgery or imitation of the printed material 100 is difficult. Moreover, since the printed material 100 further includes the IC chip 50 and the printed layer 40 in addition to the display body 1, it is possible to adopt anti-counterfeiting measures using them.

  11 and 12 exemplify an IC card as a printed material including the display body 1, the printed material including the display body 1 is not limited to this. For example, the printed matter including the display body 1 may be another card such as a magnetic card, a wireless card, and an ID (identification) card. Alternatively, the printed matter including the display body 1 may be securities such as gift certificates and stock certificates. Alternatively, the printed matter including the display body 1 may be a tag to be attached to an article to be confirmed as a genuine product. Alternatively, the printed matter including the display body 1 may be a package body that contains an article to be confirmed to be genuine or a part thereof.

  Moreover, in the printed matter 100 shown in FIG.11 and FIG.12, although the display body 1 is affixed on the base material 60, the display body 1 can be supported on a base material by another method. For example, when paper is used as the base material, the display body 1 may be rolled into the paper and the paper may be opened at a position corresponding to the display body 1. Alternatively, when a light-transmitting material is used as the base material, the display body 1 may be embedded therein, or the display body 1 may be fixed to the back surface of the base material, that is, the surface opposite to the display surface. .

  Moreover, the labeled article may not be a printed material. That is, the display body 1 may be supported on an article that does not include a printed layer. For example, the display body 1 may be supported by a luxury product such as a work of art.

  Furthermore, you may use the display body 1 for purposes other than forgery prevention. For example, the display body 1 can be used as a toy, a learning material, or a decoration.

  DESCRIPTION OF SYMBOLS 1 ... Display body, 10 ... 1st interface part, 11 ... Light transmission layer, 12 ... Reflection layer, 40 ... Printing layer, 50 ... IC chip, 60 ... Base material, 100 ... Printed material, 111 ... Light transmission base material, 112 ... light-transmitting resin layer, AD ... average center distance, DLb ... first order diffracted light, DLg ... first order diffracted light, DLr ... first order diffracted light, DS ... first relief structure, DS1 ... first relief structure, DS2 ... first 1 relief structure, DS3 ... 1st relief structure, DS4 ... 1st relief structure, DS5 ... 1st relief structure, GR ... diffraction grating, IF ... interface, IL ... white illumination light, NL ... normal, PR ... convex part, RL: specularly reflected light or 0th order diffracted light, SA: sub-region, α: incident angle, βb: exit angle, βg: exit angle, βr: exit angle.

Claims (8)

A first interface section partitioned into a plurality of regularly arranged sub-regions;
Each of the plurality of sub-regions is
A plurality of convex portions or concave portions regularly arranged with an average center-to-center distance of 200 nm or more and 500 nm or less, and a convex portion row formed by the plurality of convex portions or a concave portion row formed by the plurality of concave portions A first relief structure having
A display body comprising the plurality of sub-regions having different extending directions of the convex portion rows or the concave portion rows of the first relief structure. The plurality of sub-regions having different extension directions of the convex row or the concave row of the first relief structure,
The display body according to claim 1, wherein an absolute value of a difference in azimuth angle in the extension direction of the convex row or the concave row is continuously arranged adjacent to each other within 10 °. For each of the plurality of sub-regions in which the extension direction of the convex portion row or the concave portion row of the first relief structure is different,
The display body according to claim 1, wherein the average center distance is different. The plurality of sub-regions having different extension directions of the convex row or the concave row of the first relief structure,
4. The display body according to claim 1, wherein the display bodies are regularly arranged in a checkered pattern or a stripe pattern at intervals of 3 μm or more and 300 μm or less. When the portion corresponding to the first interface portion is observed under a condition where diffracted light from the first relief structure can be perceived,
For each of the plurality of sub-regions in which the extension direction of the convex portion row or the concave portion row of the first relief structure is different,
The display body according to claim 4, wherein the display body is configured to display a multicolor image having different colors corresponding to the difference in the average center-to-center distance.   The display body according to claim 5, comprising a plurality of sub-regions in which the extending direction of the convex portion row or the concave portion row of the first relief structure differs by approximately 45 °.   The display according to any one of claims 1 to 6, wherein an average height or an average depth of the plurality of protrusions or recesses is larger than the average center-to-center distance of the plurality of protrusions or recesses. body.   A labeled article comprising the display body according to any one of claims 1 to 7 and an article supporting the display body.

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