JP2017032900A - Display body and article having display body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a display body having a fine rugged structure, appearing black or dark gray under a normal illumination and exhibiting bright colors when observed in a specific condition, the display body enabling gradation expression of higher definition of an image pattern composed of bright colors observed in the specific condition.SOLUTION: In a display body, a relief structure formation layer includes a rugged structure region having a first rugged structure part, and a second rugged structure part neighbouring the first rugged structure having a smaller center-to-center dimension than a center-to-center dimension of recesses or projections of the first rugged structure part, thus enabling gradation expression of unprecedented higher definition.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a display body that uses an optical technique to provide a decorative effect and / or an aesthetic effect from its visual characteristics, with a focus on anti-counterfeiting technology.

  For authentication items such as cash cards, credit cards, ID cards and passports, securities, certificates, etc., it is desirable that forgery is difficult. Therefore, conventionally, such an article may support a display body excellent in forgery prevention effect.

  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 anti-counterfeit technology to such articles is increasing.

  One type of such a display body includes a fine structure such as a diffraction grating, a porogram, and a lens array. These fine structures are difficult to analyze, and in order to manufacture a display body including these fine structures, an expensive manufacturing facility such as an electron beam drawing apparatus is required. It can be demonstrated.

  Patent Document 1 describes a display body formed by arranging a plurality of pixels. In this display body, each pixel includes a relief type diffraction grating in which a plurality of grooves are arranged.

  Since this display body displays an image using diffracted light, it cannot be counterfeited using a printing technique or an electrophotographic technique. Therefore, it is possible to confirm that the article is genuine by attaching the display body to the article as a label for authenticity determination or a transfer foil.

  However, the relief-type diffraction grating formed with the grooves described above can be made to be similar at first glance with a laser or other device, and therefore a method for forming a finer structure has been found. It has been.

  For example, Patent Document 2 describes a display body including a concavo-convex structure region including a plurality of concave portions and / or convex portions arranged two-dimensionally.

  This display has a fine structure as compared to a relief type diffraction grating having a conventional groove and a so-called embossed hologram, and forgery by a device such as a laser is difficult. In addition, unlike embossed holograms, it looks “black” or “dark gray” under normal illumination conditions, and a vivid color can be seen under certain conditions, that is, at a shallow angle with respect to the display surface of the display. Is.

  Further, Patent Document 3 discloses a technique for improving the display effect when observing at a shallow angle with respect to the display surface of the display body under the specific condition, that is, the display body, by combining the concavo-convex structure region and a printing technique. Have been described.

JP-A-2-72320 Japanese Patent No. 4998405 Japanese Patent No. 4420138

  An object of the present invention is to realize a higher anti-counterfeit effect, which appears to be “black” or “dark gray” under the normal lighting conditions, and has a shallow angle with respect to a specific condition, that is, the display surface of the display body. In a display that shows vivid colors when observed with, the pattern by diffracted light observed under the specific conditions such as high-definition gradation expression and fine pattern that could not be realized in combination with conventional printing technology It is intended to enable expression.

The present invention has been made to solve these problems.
That is, the invention according to claim 1 is a relief structure comprising a light-transmitting base material and a concavo-convex structure region provided on at least one surface of the base material and on a surface opposite to the surface in contact with the base material. A display layer comprising a forming layer and a reflective layer covering at least a part of the uneven structure region of the relief structure forming layer, wherein the uneven structure region of the relief structure layer is at least a first uneven structure portion; It consists of a second concavo-convex structure portion provided adjacent to this,
The first concavo-convex structure portion is composed of a plurality of recesses or projections arranged two-dimensionally, the distance between the centers of the adjacent recesses or projections is constant and 400 nm or less, and the recesses or projections The height in the direction perpendicular to the surface of the substrate is 200 nm to 600 nm, and when viewed from the normal direction under normal illumination conditions, black or dark gray is displayed and the diffracted light emission function under specific conditions Have
The second concavo-convex structure portion is composed of a plurality of concave portions or convex portions arranged two-dimensionally, the distance between the centers of the concave portions or convex portions is constant, and the distance between the centers of the concave portions or convex portions of the first concavo-convex structure portion. A color that is smaller than the distance and 250 nm or less and that is perceived as the same color as black or dark gray when viewed from the normal direction under the normal illumination condition, and diffracted light under the specific condition It is a display body characterized by not having an injection function.

  Next, the invention according to claim 2 is configured such that the concavo-convex structure region of the relief structure forming layer is formed by arranging a plurality of cells, and a single cell includes at least the first concavo-convex structure portion. Each of the plurality of cells has an arbitrary area ratio between 100% and 0% of the second concavo-convex structure portion in the single cell. It is set as a ratio and is a display body of Claim 1 characterized by the above-mentioned.

  According to a third aspect of the present invention, the concavo-convex structure region of the relief structure forming layer is formed by arranging a plurality of cells, and the plurality of cells includes at least the first concavo-convex. 2. The display body according to claim 1, wherein the display body includes a plurality of types of cells formed by either the structure portion or the second uneven structure portion, and is arranged.

  The invention according to claim 4 is an article with a display body, characterized in that the display body according to any one of claims 1 to 3 is partially or entirely provided.

  According to the present invention, it looks black or dark gray under the normal illumination conditions, and is observed with a conventional embossed hologram or the like under the specific conditions, that is, when observed at a shallow angle with respect to the display surface of the display body. Visible colors (emitted diffracted light) that could not be observed can be observed, and the light and dark gradations of the emitted diffracted light can be expressed with higher definition and richness than before, as well as fine patterns. Therefore, the effect of preventing forgery / tampering can be improved.

It is a top view which shows roughly the display body concerning one aspect | mode of this invention. It is sectional drawing which shows typically the cross section along the ZZ line of the display body shown in FIG. It is a perspective view which shows typically an example of the uneven structure area | region of the display body of this invention. It is a figure which shows roughly a mode that an uneven | corrugated structure area | region emits a diffracted light. It is a top view which shows one example which changes the area ratio of the 1st uneven structure part in the single cell of this invention, and the 2nd uneven structure part, and expresses a gradation. It is a top view which shows an example which expresses a gradation by the method of arranging the single cell which consists of the 1st uneven structure part of this invention, and the single cell which consists of a 2nd uneven structure part. It is a top view which shows the example of fine pattern creation of this invention. It is a top view which shows the card example which affixed the display body of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In each figure, the same reference numerals are assigned to calibration elements that exhibit the same or similar functions, and duplicate descriptions are omitted.

  FIG. 1 is a plan view schematically showing a display body according to one embodiment of the present invention. FIG. 2 is a cross-sectional view schematically showing a cross section taken along the line ZZ of the display body shown in FIG.

  The display body 100 includes a light-transmitting base material 101 and a relief structure forming layer 102 provided on one surface of the base material 101 and having a concavo-convex structure region 200 on a surface opposite to the surface in contact with the base material 101. And a reflective layer 103 that covers at least a part of the concavo-convex structure region 200 of the relief structure forming layer, and the concavo-convex structure region includes a first concavo-convex structure portion 201 and a second concavo-convex structure portion 202 adjacent thereto. It is made up of.

  The light transmissive substrate 101 is a film or sheet made of a light transmissive resin such as polycarbonate (PC), acrylic, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), or triacetyl cellulose (TAC). . Moreover, there is no problem even if an inorganic material such as glass is used as the material of the substrate 101. The base material 101 may have a single layer structure or a multilayer structure. Furthermore, the substrate 101 may be subjected to various processes such as an antireflection process, a low antireflection process, a hard coat process, an antistatic process and an antifouling process, or an easy adhesion process.

  As the material of the relief structure forming layer 102, for example, a resin having optical transparency can be used. By using a thermoplastic resin, a thermosetting resin, a radiation curable resin such as light or an electron beam, and the like. The concavo-convex structure region 200 composed of a plurality of concave portions or convex portions can be easily formed on one surface of the substrate 101 by a hot-pressure transfer method using an original plate. Further, the material of the base material 101 and the relief structure forming layer 102 may be the same or different, and further, a release layer or a release layer between the base material 101 and the relief structure formation 102, An intermediate layer, a printed layer, an optical functional layer, and the like can be arbitrarily provided.

  Examples of the optical functional layer include a liquid crystal material such as cholesteric liquid crystal, and an ink layer containing a pigment in which the surface of a transparent or translucent pigment is coated with a substance having a different refractive index, but is not limited thereto. Absent.

  As the light reflection layer 103, for example, a metal layer made of a metal material such as aluminum, copper, silver, chromium, and alloys thereof can be used. Alternatively, a dielectric layer having a refractive index different from that of the relief structure forming layer 102 may be used as the light reflecting layer 103. Alternatively, as the light reflecting layer 103, a laminate of dielectric layers having different refractive indexes between adjacent ones, that is, a dielectric multilayer film may be used. However, the refractive index of the dielectric layer included in the dielectric multilayer film that is in contact with the relief structure forming layer 102 is preferably different from the refractive index of the relief structure forming layer 102.

  In addition, the reflective layer is formed by a chemical etching method patterned using a mask printing layer or a photoresist, or after pattern printing is performed on the relief structure forming layer 102 with an ink made of a water-soluble resin, and then a light emitting method such as a vapor deposition method or a sputtering method. The light reflection layer may be provided in a pattern using an aqueous etching method in which a reflection layer is provided and then washed with water including a water-soluble resin.

  FIG. 3 is an enlarged perspective view showing an example of a structure that can be adopted in the concavo-convex structure region 200 of the display body shown in FIGS. 1 and 2.

  A plurality of convex portions 210 are provided in the concavo-convex structure region shown in FIG. Here, although the concavo-convex structure region 200 is formed only by the plurality of convex portions 210, this is merely an example, and in the present invention, the concavo-convex structure region 200 can be formed using a plurality of concave portions.

  1 and 2 show a concavo-convex structure region 200 and a non-recessed structure region 220, the non-recessed structure region 220 has a substantially flat structure in which no relief structure is formed. However, a diffraction grating pattern region having a fine groove structure or the like may be provided. A diffraction grating pattern display attached to securities or the like has an effect of shining iridescent light by diffracted light being emitted by a light reflecting layer such as aluminum and a diffraction grating structure. Under observation conditions in which diffracted light from the diffraction grating structure is not emitted to the viewer, only the metallic luster (for example, gold or silver) of the light reflecting layer is perceived. In the display body including the concavo-convex structure region 200 and the diffraction grating pattern region, a so-called hologram-like image composed of the diffraction grating pattern can be displayed in black or dark gray which cannot be expressed by the conventional diffraction grating pattern display body. A visual effect different from that of the conventional diffraction grating pattern display can be obtained. By providing the diffraction grating pattern region, it is possible to enhance the decorativeness at the time of observation and at the same time obtain a higher forgery prevention effect.

  The display body 100 may be provided with various layers such as an intermediate layer, a printing layer, a pressure-sensitive adhesive, and a heat-sensitive adhesive layer on the side having the reflective layer 103 according to the purpose of use.

  Next, the special visual effect of the display body 100 resulting from the uneven structure region 200 will be described.

  The surface area of a single recess or protrusion provided in the relief structure forming layer 102 in the present invention is 1.5 times the occupation area required for arranging the single recess or protrusion on the surface of the relief structure forming layer 102. The above is preferable. When the surface area of a single concave portion or convex portion is 1.5 times or more of the occupied area, good low reflectivity and low scattering properties can be obtained. That is, it becomes easy to recognize as black when visually observed. On the other hand, if the surface area of a single concave or convex portion is smaller than 1.5 times the occupied area, the reflectivity increases, which is not preferable.

  As a method for forming the plurality of concave portions or convex portions formed in the relief structure forming layer, various methods such as radiation curing molding, extrusion molding, and hot press molding can be used using a metallic stamper or the like. In addition, examples of the shape used for the plurality of concave portions or convex portions in which the relief structure forming layer is formed include, for example, a cone shape, a pyramid shape, an elliptical cone shape, a columnar shape or a cylindrical shape, a prismatic shape or a rectangular tube shape, and a wharf Conical shape, truncated pyramid shape, truncated elliptical cone shape, shape in which a cone is joined to a cylinder or cylinder, shape in which a pyramid is joined to a prism or square tube, hemisphere, semi-ellipsoid, bullet shape, bowl shape, etc. Can be mentioned.

  In particular, it is preferable that the cross sections of the plurality of concave portions or convex portions formed in the relief structure forming layer have a tapered shape. This is because, when the cross section of the plurality of concave portions or convex portions is tapered, the mold release property between the metallic stamper and the resin is high and the mass productivity is excellent. Furthermore, when the cross section of a some recessed part or a convex part is a taper shape, the low reflection property and the low scattering which are more favorable than the cross section of a some recessed part or a convex part can be obtained.

  Here, the taper shape refers to a case where the cross-sectional area parallel to the substrate surface of the concave portion or convex portion is formed so as to decrease from the proximal end to the distal end of the concave portion or convex portion.

  As shown in FIG. 3, when the center-to-center distance between adjacent recesses or protrusions is constant in the concavo-convex structure region 200, when the concavo-convex structure region 200 is irradiated with light as shown in FIG. 200 emits diffracted light in a specific direction with respect to the traveling direction of the incident light 301.

  In general, the diffracted light can be expressed by the following formula.

d (sin α ± sin β) = nλ (1)
In this equation (1), d represents the distance between the centers of the concave or convex portions, and λ represents the wavelengths of incident light and diffracted light. Further, α represents the incident angle of the incident light, β represents the exit angle of the diffracted light, n is the order, and the most typical diffracted light is the first order diffracted light, so n = 1. be able to.

Here, the incident angle α can be considered to be the same as the exit angle of the 0th-order diffracted light, that is, the specularly reflected light, and α and β are normal directions to the display body, that is, clockwise from the Z axis in FIG. The direction is the positive direction.
Thus, equation (1) becomes:

d (sin α−sin β) = λ (2)
Therefore, when the center-to-center distance d of the concave portion or the convex portion and the incident angle, that is, the exit angle α of the 0th-order diffracted light are made constant, as is apparent from equation (2), the exit angle β of the first-order diffracted light 303 is It changes according to the wavelength λ.
That is, the concavo-convex structure region 200 has a function as a spectroscope. Therefore, when the illumination light is white light, the color perceived by the observer changes when the observation angle of the concavo-convex structure region 200 is changed.

In addition, the color perceived by the observer under a certain observation condition changes according to the center distance d between the concave or convex portions. As an example, it is assumed that the uneven structure region 200 emits the first-order diffracted light 303 in the normal direction. That is, the exit angle β of the first-order diffracted light 303 is assumed to be 0 °. Assume that the observer perceives this first-order diffracted light. If the exit angle of the 0th-order diffracted light 302 at this time is α _N , equation (2) can be simplified to equation (3) below.

d = λ / sin α _N (3)
As is clear from equation (3), in order for the observer from the normal direction to perceive a specific color, the wavelength λ corresponding to the color and the incident angle | α _N | The distance d may be set so that they satisfy the relationship shown in equation (3).

  The concavo-convex structure region 200 in the present invention is composed of a first concavo-convex structure portion 201 and a second concavo-convex structure portion 202, each of which is composed of a plurality of concave or convex portions arranged two-dimensionally, The center-to-center distance of each concave or convex portion is 400 nm or less in the first concavo-convex structure portion 201, and is smaller than the first concavo-convex structure portion 201 in the second concavo-convex structure portion 201, And it is 250 nm or less.

That is, even when d = 400 nm and an incident angle α _N = 90 °, which is not normal, the wavelength of light that can be observed from the normal direction is 400 nm. Therefore, in the first uneven structure portion 201, the reflectance of the regular reflection light 302 with respect to the incident light 301 can be significantly reduced, and depending on the incident angle of the incident light 301 due to the periodicity of the structure, visible light can be reduced. The first-order diffracted light 303 can be generated in a specific direction.

  Therefore, for example, when the display body 100 is observed from the normal direction under normal illumination conditions, the first concavo-convex structure portion looks black or dark gray.

  Further, if the emission angle of the first-order diffracted light 303 from the first concavo-convex structure portion 201 is within a range of −90 ° to 90 °, an angle formed by the normal direction of the display body 100 and the observation direction is appropriately set. Thus, the observer can perceive the first-order diffracted light 303 from the first uneven structure portion 201. Therefore, in this case, it can be visually confirmed that the first uneven structure portion 201 is different from black or dark gray.

  On the other hand, in the second concavo-convex structure portion 202, the distance between the centers of the concave or convex portions is smaller than that of the first concavo-convex structure portion 201 and 250 nm or less, and more preferably, the distance between the centers of the concave or convex portions is 200 nm or less. Accordingly, the reflectance of the regular reflection light 302 with respect to the incident light 301 can be reduced in the same manner as the first concavo-convex structure portion 201, and the second concavo-convex structure portion 202 is also black when observed from the normal direction. Or it can appear dark gray. Furthermore, since the distance between the centers of the concave or convex portions of the second concavo-convex structure portion 202 is 250 nm or less, the first-order diffracted light 303 from the second concavo-convex structure portion 202 is related to the first-order diffracted light 303 with respect to the incident light 301. Even if the first diffracted structure portion 201 is under the condition that the first-order diffracted light 303 can be visually observed, the second concavo-convex structure portion 202 cannot observe the first-order diffracted light 303.

  Furthermore, by setting the distance between the centers of the recesses or projections to 200 nm or less, even if the incident angle of the irradiation light, that is, the emission angle α of the 0th-order diffracted light is 90 °, and the light wavelength is 400 nm, the first-order diffracted light 303 is It is a situation where observation is finally possible at an angle of emission | β | = 90 °. Therefore, if the distance between the centers of the concave portions or the convex portions is 200 nm or less, the first-order diffracted light 303 can hardly be observed.

  Accordingly, by providing the first concavo-convex structure portion 201 and the second concavo-convex structure portion 202 adjacent to each other in a pattern, the first concavo-convex structure portion and the second concavo-convex structure portion are provided under the normal illumination condition. Both appear black or dark gray, and when the emission state of the first-order diffracted light 303 under the specific conditions is visually observed, only the emission pattern of the first-order diffracted light 303 from the first concavo-convex structure portion is observed with high contrast. It becomes possible.

  Here, FIGS. 5 and 6 show the arrangement method of the first concavo-convex structure portion 201 and the second concavo-convex structure portion 202, thereby realizing a high-definition gradation expression that has not been conventionally achieved. .

  In FIG. 5, the concavo-convex structure region 200 is formed by an array of a plurality of cells 400, and a first concavo-convex structure portion 201 and a second concavo-convex structure portion 202 are provided in the single cell 400. The gradation is expressed by arbitrarily changing the area occupied by the second uneven structure portion 202.

  By arranging the cells 400 thus formed in an arbitrary pattern, when the display body 100 is observed from the normal direction, the portion observed uniformly in black or dark gray is By observing under specific conditions, the first-order diffracted light 303 emitted from the first concavo-convex structure portion 201 can be visually observed, and in this case, from the first concavo-convex structure portion 201 and the second concavo-convex structure 202. High-definition gradation expression can be observed according to the arrangement pattern of the cell groups.

  The effect of producing the difference between the pattern expressed in black or dark gray observed from the normal direction of the display body 100 and the pattern visually observable by the first-order diffracted light 303 under the specific condition is as follows. A similar effect can also be produced by combining a concavo-convex structure region composed of the concavo-convex structure portion 201 and a printing layer using black ink. However, according to the method of the present invention, a fine technique that is difficult to reproduce by a printing technique is obtained. The cell 400 can be formed. For example, the cell 400 having a size of 100 μm square or less, and more desirably 50 μm square or less can be arbitrarily designed. Thus, high-definition gradation expression that is difficult to express becomes possible.

  Here, FIG. 5 shows an example of the formation pattern of the second concavo-convex structure portion 202 in the cell 400, but gradation expression is possible depending on the area ratio of the second concavo-convex structure portion 202 in the cell 400. Therefore, the arrangement pattern of the second concavo-convex structure 202 in the cell 400 can be arbitrarily set.

  In FIG. 6, the concavo-convex structure region 200 is formed by an arrangement of a plurality of cells 400, and the single cell 400 includes a first concavo-convex structure portion 201 and a second concavo-convex structure portion 202. Some of these cells are arbitrarily arranged to realize high-definition gradation expression. Also in the method of FIG. 6, the size of the single cell 400 can be arbitrarily designed, and gradation expression that is difficult to express by combination with printing can be achieved.

  The image pattern having a high-definition gradation expression as described above is a latent image pattern that is difficult to recognize under the normal illumination conditions, and tilts the concavo-convex structure region 200 to a predetermined angle under the specific conditions. By observing in a state in which the first concavo-convex structure is observed, an image composed of the first concavo-convex structure portion 201 and the second concavo-convex structure 202 can be observed.

  Further, by using these techniques, as shown in FIG. 7, it is possible to incorporate fine pattern information that is difficult to confirm visually, and illumination for incident light 301 so that the specific condition can be reproduced. It is possible to determine the authenticity by a reading apparatus in which a light source is arranged and a first-order diffracted light 303 can be observed and a camera having a lens function capable of reading a fine pattern is arranged. It is possible to provide a display body having a high anti-counterfeit / tampering function.

  FIG. 8 is an explanatory view schematically showing an example of an article provided with the display body 100 of the present invention. Here, a card is illustrated as an article, but the article including the display body 100 is not limited to this.

  As the display body 100 to be affixed to a card or the like, for example, by combining with the diffraction grating pattern region, the design is high even under normal illumination conditions, and a high-definition latent image is obtained from the concavo-convex structure region 200 even under the specific conditions. Provided is a security article having a high anti-counterfeiting / tampering effect that can be confirmed by visual observation, and that can be verified by a verification device by providing a fine pattern as illustrated in FIG. It becomes possible.

DESCRIPTION OF SYMBOLS 100 ... Display body 101 ... Light-transmitting base material 102 ... Relief structure formation layer 103 ... Reflective layer 200 ... Uneven structure area 201 ... 1st uneven structure part 202 ... 2nd uneven structure part 210 ... Convex part 220 ... Non uneven | corrugated Structure region 301 ... Incident light 302 ... Regular reflection light or zero-order diffracted light 303 ... First-order diffracted light 400 ... Single cell 500 ... Card

Claims (4)

A light-transmitting base material, a relief structure-forming layer provided on at least one surface of the base material, and having a concavo-convex structure region on a surface opposite to the surface in contact with the base material, and the unevenness of the relief structure-forming layer A display body including a reflective layer covering at least a part of a structural region,
The concavo-convex structure region of the relief structure layer comprises at least a first concavo-convex structure portion and a second concavo-convex structure portion provided adjacent thereto,
The first concavo-convex structure portion is composed of a plurality of recesses or projections arranged two-dimensionally, the distance between the centers of the adjacent recesses or projections is constant and 400 nm or less, and the recesses or projections The height in the direction perpendicular to the surface of the substrate is 200 nm to 600 nm, and when viewed from the normal direction under normal illumination conditions, black or dark gray is displayed and the diffracted light emission function under specific conditions Have
The second concavo-convex structure portion is composed of a plurality of concave portions or convex portions arranged two-dimensionally, the distance between the centers of the concave portions or convex portions is constant, and the distance between the centers of the concave portions or convex portions of the first concavo-convex structure portion. A color that is smaller than the distance and 250 nm or less and that is perceived as the same color as black or dark gray when viewed from the normal direction under the normal illumination condition, and diffracted light under the specific condition A display body characterized by not having an injection function.   The concavo-convex structure region of the relief structure forming layer is formed by arranging a plurality of cells, and a single cell includes at least the first concavo-convex structure portion and the second concavo-convex structure portion, The plurality of cells are arranged such that the area ratio occupied by the second concavo-convex structure portion in the single cell is an arbitrary ratio between 100% and 0% for each cell. The display body according to claim 1.   The concavo-convex structure region of the relief structure forming layer is formed by arranging a plurality of cells, and each of the plurality of cells includes at least the first concavo-convex structure portion or the second concavo-convex structure. The display body according to claim 1, wherein the display body includes a plurality of types of cells formed by any of the sections and is arranged.   An article with a display body, wherein the display body according to any one of claims 1 to 3 is provided in part or in whole.