JP4983899B2 - Display and labeled goods - Google Patents

Description

  The present invention relates to a display technology that provides an anti-counterfeit effect.

  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, Non-Patent Document 1 describes the principle that incident light (white light) changes to a rainbow-colored spectral color by the diffraction grating.

In a display body using a diffraction grating, a relief type diffraction grating formed with a plurality of grooves is generally used. A relief type diffraction grating is usually obtained by replicating an original plate produced using photolithography as a mother die. For example, Patent Document 1 and Patent Document 2 display a picture by appropriately changing the grating angle and the grating interval (grating pitch) of the diffraction grating by utilizing the spectral color that the diffraction grating shines in rainbow colors. Is described. In the display formed by a plurality of diffraction grating structures with different grating angles and intervals, the wavelength of the diffracted light that reaches the eyes of the observer gradually changes as the position of the observer and the position of the light source change. Thus, an image that changes to a rainbow color can be expressed.
In addition, in these documents, 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 controlled under computer control. Describes a method of exposing the photosensitive resist to a pattern by irradiating the photosensitive resist with an electron beam while moving. Non-Patent Document 2 describes a method of forming a diffraction grating using two-beam interference. In the manufacture of the relief type diffraction grating, the original stamp obtained in this way is usually used, and a metal stamper is produced 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 to a film or sheet-like thin transparent substrate 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.

JP-A-2-72320 US Pat. No. 5,058,992

Edited by Junpei Takiuchi, "Holographic Display", Sangyo Tosho Co., Ltd. Junpei Takiuchi, "Holography", Maruzen Co., Ltd.

  The present invention solves the above-described conventional problems, and an object thereof is to provide a display body and a labeled article that exhibit a high anti-counterfeit effect.

In order to achieve the above object, the present invention covers a light-transmitting base material, a concavo-convex structure forming layer provided on one surface side of the base material, and at least a part of the concavo-convex structure forming layer. A display body comprising a reflective layer, wherein the concavo-convex structure forming layer has a plurality of convex portions whose top surface is substantially parallel to the base material surface, or a plurality of concave portions whose bottom surface is substantially parallel to the base material surface. And at least one region formed by arranging a flat portion substantially parallel to the substrate surface, and the plurality of convex portions or concave portions each have a long side and a short side length of 5 μm or more and 50 μm or less, an average arrangement interval of adjacent convex portions or concave portions is 5 μm or more and 50 μm or less, and an occupation area of the convex portions or concave portions in the region is 20% or more and 80% or less, The height of the recess is 0.1 μm or more and 0.5 μm or more. , And the height of the plurality of projections or recesses is a display body, wherein different for each region.
Moreover, 2nd invention is a display body of Claim 1 from which the height of the some convex part or recessed part arrange | positioned in the said area | region differs, respectively.
Moreover, 3rd invention is the display body in any one of Claim 1 or 2 characterized by the same shape and area of the some convex part or recessed part arrange | positioned in the said area | region. .
In addition, according to a fourth aspect of the present invention, the plurality of convex portions or concave portions arranged in the region are regularly arranged at regular intervals in an arbitrary direction. It is a display body.
A fifth aspect of the present invention is characterized in that the height of the plurality of projections or recesses arranged in the area, or the shape or at least one of the surfaces product is, are different from each projection or each recess The display body according to claim 1.
Further, the sixth invention is characterized in that an arrangement interval between the convex portion or the concave portion arranged in the region and the peripheral convex portion or concave portion adjacent to the convex portion or the concave portion is random at least in a part of the region. The display body according to claim 5.
Moreover, 7th invention is a display body in any one of Claims 1-6 characterized by the shape of the said convex part or a recessed part being a polygon which has a circle or five or more vertices.
The eighth invention is the display body according to any one of claims 1 to 7 , wherein the area occupied by the plurality of convex portions or concave portions in the region is approximately 50%.
The ninth invention is a labeled article comprising the display according to any one of claims 1 to 8 and an article supporting the display.

By setting it as the structure of this invention, the display body which displays the color comprised from the light of a several wavelength in the direction near the regular reflection direction of illumination light is obtained. Unlike a relief type diffraction grating pattern, this display body hardly changes its color to iridescent according to changes in the position of the illumination or the position of the observer, and is different from conventional display bodies for the purpose of preventing counterfeiting. Visual effects can be realized. As a result, it is possible to obtain a display body that has a high eye-catching effect (eye-catching effect) and exhibits a high anti-counterfeit effect.
Further, according to the second invention, for example, light incident on a display body in which a plurality of irregular shapes having different structure heights are irregularly arranged is a so-called mixed color in which a plurality of diffracted lights having different strengths are mixed. Display is possible, and it is possible to express a color of a hue that is more difficult to reproduce than an uneven shape having a constant structure height.
In addition, according to the third invention, the same shape can suppress the generation of light other than diffracted light (stray light such as scattered light), and can prevent a decrease in the saturation of the display color. Further effects can be obtained.
In addition, according to the fourth invention, when a plurality of convex portions or concave portions are regularly arranged in a given interval with respect to an arbitrary direction, the effect of obtaining diffracted light with less stray light can be obtained due to the periodicity of the structure. Obtainable.
Further, according to the fifth and sixth inventions, the arrangement of the structures such as staggering the structures of different shapes by at least one of the height, shape, area or arrangement interval of the plurality of protrusions being different. Can have a specific meaning. And since minute unevenness | corrugation shape is a special arrangement | sequence, it cannot be confirmed visually. Therefore, what is counterfeited is very effective in restraining the production of counterfeit products because it is necessary to counterfeit not only the appearance similarity but also the uneven shape. It becomes possible to improve the difficulty of creation.
In addition, according to the first invention, a different color can be displayed for each region by changing the height of the convex portion (or the depth of the concave portion) for each first region. That is, a display body capable of displaying a plurality of colors can be realized.
According to the seventh invention, a circle or a polygon having many vertices exhibits a substantially uniform optical effect with respect to the azimuthal direction of the display body surface. Therefore, by forming these shapes in the first region, there is an effect that the same display color can be obtained relatively stably even when the viewing direction of the display body and the position of the light source are changed.
Further, according to the eighth invention, from the formula (2), the diffraction efficiency becomes the highest when the width of the convex portion or the concave portion (corresponding to the lattice line width L of the formula (2)) is half of the pitch d. Therefore, the remarkable effect that the brightest display image can be obtained when the area occupied by the convex portion or the concave portion is about 50% can be obtained.
According to the ninth invention, it is possible to give a high anti-counterfeiting effect to a conventional article by bonding or combining the display body of the present invention to a printed matter, a card, or other articles.

The top view which showed roughly the display body which concerns on 1 aspect of this invention. The expanded sectional view of the display body which follows the II-II line of FIG. The figure which showed a mode that the diffraction grating inject | emitted + 1st-order diffracted light. The figure which showed a mode that the display body of this invention inject | emitted + 1st-order diffracted light. The top view which shows an example of the structure which can be employ | adopted as the 1st area | region of the display body of this invention. The expanded sectional view of the display body which follows the III-III line of FIG. The top view which shows another example of the structure employable as a 1st area | region. The top view which shows another example of the structure employable as a 1st area | region. The top view which shows another example of the structure employable as a 1st area | region. The top view which shows another example of the structure employable as a 1st area | region. Schematic which shows the mode of the diffracted light inject | emitted from a diffraction grating. Schematic which shows the mode of the diffracted light inject | emitted from the display body of this invention. The top view which shows an example of the structure which consists of several convex parts from which the shape and area which can be employ | adopted as the 1st area | region of the display body shown in FIG.1 and FIG.2 differ. The perspective view which shows an example of the antireflection structure which is a structure employable as the 2nd area | region of the display body shown in FIG.1 and FIG.2. The perspective view which shows an example of the light-scattering structure which is a structure employable as the 2nd area | region of the display body shown in FIG.1 and FIG.2. The top view which shows roughly an example of the labeled article formed by making an anti-counterfeit label supported on the article. Sectional drawing along the IV-IV line of the labeled article shown in FIG.

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

  FIG. 1 is a plan view schematically showing a display according to an aspect of the present invention, and an example of a display that displays a color composed of light of a plurality of wavelengths in a direction close to the regular reflection direction of the present invention. Is shown. 2 is a cross-sectional view taken along the line II-II of the display shown in FIG. The display body 10 includes a laminated body of the light transmission layer 11 and the reflection layer 13. In this example, the light transmission layer 11 is a relief structure forming layer. In the example shown in FIG. 2, the light transmission layer 11 side is the front side (observer side), and the reflection layer 13 side is the back side.

  The display body 10 shown in FIGS. 1 and 2 has a plurality of convex portions whose upper surface is substantially parallel to the base material surface, or a plurality of bottom surfaces that are substantially parallel to the base material surface on the surface of the concavo-convex structure forming layer. And at least one region formed by arranging a flat portion substantially parallel to the substrate surface. In the figure, the first region 15 is a region where minute irregularities are formed, and the second region 25 is defined as a region having a structure and optical properties different from those of the first region 15. The second region 25 may be a region where a concavo-convex structure different from that of the first region 15 is formed, or may be a region formed of a flat portion where no structure is formed. In addition, at least one or more first regions 15 are present in the display body 10, but a plurality of second regions 25 may be present in the display body 10, or none may be present. . A plurality of regions may be combined to form a display body.

  As a material of the light transmission layer 11, for example, a resin having light permeability such as a thermoplastic resin or a photocurable resin can be used. When a thermoplastic resin or a photo-curing resin is used, for example, from a metal stamper in which a convex structure or a concave structure of the display body is formed, a light transmission layer 11 having a convex structure or a concave structure provided on one main surface. Can be transfer molded.

  In FIG. 2, as an example, the light transmissive layer 11 constituted by a laminate of a light transmissive substrate 111 and a light transmissive resin layer 112 is depicted. The light-transmitting substrate 111 is a film or sheet that can be handled by itself, and for example, polyethylene terephthalate (PET) or polycarbonate (PC) can be used. The light transmissive resin layer 112 is a layer formed on the light transmissive substrate 111. The light transmissive layer 11 shown in FIG. 2 is obtained, for example, by applying a thermoplastic resin or a photocurable resin on a light transmissive substrate 111 and curing the resin while pressing a stamper against the coating film. .

  As the reflective layer 13, 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 13. Alternatively, as the reflective layer 13, a laminate of dielectric layers having different refractive indexes between adjacent ones, that is, a dielectric multilayer film may be used. Of the dielectric layers included in the dielectric multilayer film, those in contact with the light transmission layer 11 desirably have a refractive index different from that of the light transmission layer 11. The reflective layer 13 can be formed by, for example, a vapor deposition method such as a vacuum evaporation method or a sputtering method.

  The display body 10 can further include other layers such as an adhesive layer and a resin layer. For example, the adhesive layer is provided so as to cover the reflective layer 13. When the display body 10 includes both the light transmissive layer 11 and the reflective layer 13, the shape of the surface of the reflective layer 13 is usually almost equal to the shape of the interface between the light transmissive layer 11 and the reflective layer 13. When the adhesive layer is provided, it is possible to prevent the surface of the reflective layer 13 from being exposed, so that it is difficult to duplicate the convex structure or concave structure of the previous interface for the purpose of counterfeiting. The resin layer is made of, for example, a hard coat layer intended to prevent the surface of the display body from being scratched during use, or a resin ink that is provided on a part of the display body and is cured by light or heat. A printed layer.

  When the light transmission layer 11 side is the back surface side and the reflection layer 13 side is the front surface side, the adhesive layer is formed on the light transmission layer 11.

  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 13. For example, when the light transmission layer 11 side is the back side and the reflection layer 13 side is the front side, by covering the reflection layer 13 with a resin layer, damage to the reflection layer 13 can be suppressed, It is possible to make it difficult to duplicate the convex or concave structure on the surface for the purpose of counterfeiting.

(Description of the first area)
In describing the first region according to the present invention, first, the relationship between the pitch of the diffraction grating and the wavelength of the illumination light, and the illumination light incident angle and the emission angle of the diffracted light will be described.

  When the illumination light is irradiated onto the diffraction grating using the illumination light source, the diffraction grating emits strong diffracted light in a specific direction corresponding to the traveling direction of the illumination light that is incident light.

The exit angle β of m-order diffracted light (m = 0, ± 1, ± 2,...) can be calculated from Equation 1 when the light travels in a plane perpendicular to the grating line of the diffraction grating.
d = mλ / (sin α−sin β) (Formula 1)
In Equation 1, d represents the grating constant (grating period, pitch) of the diffraction grating, m represents the diffraction order, and λ represents the wavelength of incident light and diffracted light. Α represents the exit angle of the 0th-order diffracted light, that is, the regular reflection light RL. 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 line NL.

  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.

  FIG. 3 is a diagram schematically showing the state in which the diffraction grating emits the + 1st order diffracted light, and shows the relationship between the illumination light incident angle and the emission angle of the + 1st order diffracted light with respect to the diffraction grating having the pitch d. When the illumination light is white light including a plurality of wavelength components, the exit angle of the diffracted light varies depending on the wavelength. As a result, when the diffraction grating is observed under a white illumination light source such as the sun or a fluorescent lamp, white light is dispersed, and light of a single wavelength is emitted at different angles. In FIG. 3, white light IL (here, it is assumed that the wavelength components constituting the white light are three wavelengths of R, G, and B) are incident from the point light source LS, and the diffracted light of the wavelength component R by the diffraction grating GR. It shows a state where light is split into DL_r, diffracted light DL_g of wavelength component G, and diffracted light DL_b of wavelength component B. At this time, the exit angle β_r of the diffracted light of the wavelength component R, the exit angle β_g of the diffracted light of the wavelength component R, and the exit angle β_b of the diffracted light of the wavelength component R take different values for each wavelength (in FIG. , Only the exit angle of DL_r is described as β_r). Other orders of diffracted light are also emitted at angles derived from Equation 1, but are not shown in FIG.

  FIG. 4 is a diagram schematically showing a state in which the display body of the present invention emits + 1st order diffracted light, and a state in which a diffraction grating having a wider pitch emits + 1st order diffracted light compared to FIG. Show. A state in which white light is incident on a diffraction grating having a pitch d larger than that in FIG. 3 is shown. When the pitch d is large, as is clear from Equation 1, the diffracted light is emitted in a direction closer to the specularly reflected light RL as compared with the diffraction grating having a narrow pitch, and the emission angles of the separated single-wavelength light beams. The difference between is small.

  Next, the relationship between the pitch of the diffraction grating and the wavelength of the illumination light and the intensity (diffraction efficiency) of the diffracted light in the direction of the emission angle of the diffracted light will be described.

Illumination light that is incident on the diffraction grating of pitch d at an incident angle of α emits diffracted light in the direction of angle β based on Equation 1. At this time, the emission intensity of the light having the wavelength λ, that is, the diffraction efficiency, varies depending on the pitch and height of the diffraction grating and is derived by Equation 2.

  Here, η is the diffraction efficiency (having a value of 0 to 1), r is the height of the diffraction grating, L is the grating line width of the diffraction grating, d is the pitch of the grating line, θ is the incident angle of the illumination light, λ Is the wavelength of incident light and diffracted light. This equation holds for a shallow rectangular diffraction grating having a concavo-convex structure.

  As is clear from Equation 2, the diffraction efficiency varies depending on the height r of the diffraction grating, the pitch d of the grating lines, the incident angle θ of incident light, and the wavelength λ. In practice, the diffraction efficiency tends to gradually decrease as the diffraction order m becomes higher.

  Next, the structure and optical properties of the first region will be described.

  The first region has a flat portion substantially parallel to the base material surface, and a plurality of convex portions or concave portions are formed at intervals from each other, and the plurality of convex portions or concave portions are long sides and short sides. Are 5 μm or more and 50 μm or less, and an average arrangement interval between adjacent ones of the plurality of convex portions or concave portions is 5 μm or more and 50 μm or less. The area occupied by the protrusions or recesses in the first region is 20% or more and 80% or less. Further, the height of the convex portion or the depth of the concave portion is 0.1 μm or more and 0.5 μm or less.

  FIG. 5 is a plan view showing an example of a structure that can be employed in the first region of the display body of the present invention, and is a partially enlarged plan view of the first region 15 provided on the display body 10 of FIG. It is. 6 is a cross-sectional view taken along line III-III in FIG. In FIG. 5, the convex part 16 has a circular shape.

  In addition, the above-described orderly arrangement means that the convex portions or the convex portions are arranged at equal intervals or regularity, for example, a square lattice, a rectangular lattice, or a triangular lattice. By controlling the arrangement of these concave portions or convex portions, there is an advantage that diffracted light with less stray light can be obtained.

  7 to 10 are plan views showing other examples of structures that can be employed in the first region. As other examples of the convex portion or the concave portion, polygons such as an ellipse (FIG. 7), an octagon (FIG. 8), a star (FIG. 9), a cross (FIG. 10), etc. can be arbitrarily adopted.

  Moreover, the structure of the convex part or recessed part which can be employ | adopted as a 1st area | region is 5 micrometers or more and 50 micrometers or less in length of a long side and a short side, respectively, and a long side and a short side are respectively as shown in FIG. The longest part of the convex part or the concave part is defined as the long side 28 and the shortest part is defined as the short side. That is, a convex part or a recessed part is a shape enclosed in the rectangle which has a side of 5 micrometers or more and 50 micrometers or less.

  FIG. 11 is a schematic diagram showing a state of diffracted light emitted from the diffraction grating. In the diffraction grating GR formed by a plurality of grating lines parallel to the y-axis as shown in FIG. 11, the direction (x-axis) orthogonal to the y-axis (longitudinal direction of the grating lines) when the illumination light IL is incident. Diffracted light DL_r, DL_g, DL_b is emitted in the direction).

  On the other hand, FIG. 12 is a schematic view showing the state of diffracted light emitted from a display body adopting the present invention. When illumination light enters the structure as shown in FIGS. 5 and 6, the first region is shown. The diffracted light is emitted by the periodicity of the plurality of convex portions 16 formed in 15 and the surrounding flat portion 17. In the structure in which the protrusions 16 are spaced apart from each other in the first region 15 by adopting the structure of the present invention, the diffraction is not limited to the x-axis direction but is diffracted with respect to many azimuth angles on the XY plane. Light is emitted. The diffracted light emitted here is diffracted light DL_r having a long wavelength on the side closer to the incident light as in the case where the light is incident on the diffraction grating as shown in FIG. DL_g and further DL_b are emitted in the direction of moving away. FIG. 12 shows a state in which light is incident on one point in the first region. Actually, light is incident on the first region in a planar shape, not incident on one point.

  As described above, when the pitch is as large as about 5 to 50 μm and the exit angle of the diffracted light is close to the regular reflection angle of the incident light, the difference in the exit angle for each order of the diffracted light is not so large, and the display body is at a close distance. In visual observation, a plurality of orders of diffracted light enter the eye together. Further, each order of diffracted light is composed of light of a plurality of wavelengths, but since the plurality of wavelength components also have a small difference in the emission angle, the observer can select light of a plurality of orders and of a plurality of wavelengths. Can be perceived simultaneously. For example, if the wavelength components of the diffracted light reaching the eyes of the observer are red (wavelength 630 nm) and green (wavelength 540 nm), the observed color is yellow, and green and blue (wavelength 460 nm). Then, the observed color is cyan (light blue).

  Furthermore, normally, when we observe the display body under illumination such as the sun or a fluorescent lamp, the light source itself is not an ideal point light source as shown in FIG. Since the light reflected by the fine particles, the ground, the wall, etc. reaches the display body, the illumination light incident on the display body is composed of various directional components. Therefore, even when there is a light source vertically above the display body, when the display body is observed at a fixed point, the diffracted light emitted from the first region is not light of a single wavelength but from a plurality of angles. The incident light reaches the observer's eyes with light in which a plurality of wavelength components are mixed.

  Here, as shown in Expression 2, the amount of light of the diffracted light emitted from the diffractive structure, that is, the diffraction efficiency changes according to the wavelength. Therefore, even when the display body (first region) is observed from a fixed point, the wavelength component of visible light does not reach the eyes evenly, and is specified according to the height of the convex portion provided in the first region. As a result, the light reaching the observer becomes light having a reduced characteristic wavelength component in the incident white illumination light. Therefore, when observing the first region, the observer can perceive light having a plurality of wavelengths having different light amounts at an angle close to the regular reflection direction of the incident light.

  In the conventional diffraction grating, the color at which the wavelength of the diffracted light that reaches the eyes of the observer changes depending on the position of the light source and the viewing direction changes, but the structure employed in the first region of the present invention is as follows. As shown in FIG. 12, since diffracted light is emitted with respect to many azimuth angles on the XY plane, a color composed of a plurality of wavelengths is observed even if the position of the light source and the observation direction are slightly changed. Is possible. For this reason, it is possible to avoid or reduce the phenomenon that the display color changes to iridescent as in the conventional diffraction grating. The longer side and the shorter side of the convex portion or concave portion provided in the first region are closer to the same value, so that the same color can be seen stably regardless of the position of the light source and the viewing direction.

  In addition, since the wavelength at which the diffraction efficiency is lowered is changed by changing the height of the convex portion, when displaying different colors, the height of the convex portion provided in the first region (or the depth of the concave portion). ) May be changed.

(Structures and effects that can be used in the first area)
As a structure that can be adopted in the first region, the lengths of the long side and the short side of the plurality of convex portions or concave portions are 5 μm or more and 50 μm or less, respectively, and the arrangement interval (pitch) between adjacent ones is It is 5 μm or more and 50 μm or less. From the concavo-convex structure with periodicity having such a pitch, diffracted light is emitted within a range of about ± 8 ° of regular reflected light with respect to the incidence of white illumination light. If the illumination light is dispersed in such a narrow range, the spread due to the spectrum is small, and the observer can easily perceive the color due to light of a plurality of wavelengths.
Here, when the pitch of the convex part or the concave part is smaller than 5 μm, the difference in the emission angle of the light of each wavelength separated becomes large, so that it may appear iridescent like the conventional diffraction grating. Get higher. Therefore, the pitch of the convex part or the concave part is preferably 5 μm or more. Further, when the pitch of the convex portions or the concave portions is larger than 50 μm, the diffraction phenomenon itself does not occur or becomes weak, so that it is difficult to display light in which a plurality of wavelength components are mixed.

Moreover, it is preferable that the occupied area of the convex part or the concave part in the first region is 20% or more and 80% or less. From Equation 2, the diffraction efficiency is highest when the width of the convex portion or the concave portion (corresponding to the lattice line width L of Equation 2) is half of the pitch d. Therefore, the brightest display image can be obtained when the area occupied by the convex portion or the concave portion is about 50%, and it is most desirable. If it is about 20% or more and 80% or less, the diffraction efficiency decreases as the distance from 50% increases. Although the image becomes dark, it is possible to visually recognize a display image composed of light of a plurality of wavelengths. Note that the diffraction efficiency when the occupied area is 20% and 80% is about 30% of the brightness of 50% from Equation 2.
If the area occupied by the protrusions or recesses is less than 20% or greater than 80%, sufficient brightness cannot be obtained, and it becomes difficult to obtain a sufficient eye-catching effect.

  Moreover, it is preferable that the optimal value of the height of a convex part or the depth of a recessed part is the range of 0.1 micrometer or more and 0.5 micrometer or less. In Formula 2, assuming that the pitch d and the grating line width L are constant, when the light having a wavelength in the visible light range is incident at an incident angle θ (a range greater than 0 ° and less than 90 °), the diffraction efficiency is highest. The height of the convex portion or the depth value of the concave portion is in the range of 0.1 μm to 0.5 μm. Note that, from Equation 2, the conditions for the highest diffraction efficiency are repeated even when the diffraction efficiency is larger than that, but for manufacturing, it is easier to manufacture when the height of the convex portion or the depth of the concave portion is as shallow as possible. Therefore, the conditions of 0.1 μm or more and 0.5 μm or less that can obtain high diffraction efficiency at a shallower value are desirable.

  In addition, when the height of the convex part or the depth of the concave part is less than 0.1 μm, the same quality is stable due to external factors during manufacturing (variation in machine and environmental conditions, slight changes in material composition, etc.) It is difficult to fabricate the product, and when it is deeper than 0.5 μm, it becomes difficult to precisely transfer and mold a fine and deep structure.

  In addition, the plurality of convex portions or concave portions arranged in the first region have the following advantages when their shapes and areas are the same.

  1stly, the process of a concavo-convex structure becomes easy when a some convex part or a recessed part is the same shape. An original plate on which a plurality of convex portions or concave portions provided in the first region is formed can be manufactured by using a photolithography process in the same manner as a conventional relief diffraction grating manufacturing process. By exposing and developing a photosensitive resist applied to a substrate on a plane with a charged particle beam such as an electron beam or a laser, a desired uneven shape is processed. When processing the concavo-convex shape in such a process, the height (depth) of the structure is controlled by adjusting the intensity and irradiation time of the charged particle beam. At this time, if the shape and area of the concavo-convex shape are different, it is difficult to obtain a structure having a uniform height (depth) even if the intensity and irradiation time of the charged particle beam are adjusted. If the plurality of convex portions or concave portions have the same shape, a convex portion or concave portion having a uniform height (depth) can be obtained under the same processing conditions. Further, not only the photolithography process but also a process using a cutting tool such as a diamond cutting tool with a fine tip, a process of corroding the surface of a metal or the like by etching, and the like can be realized.

  Second, when the plurality of convex portions or concave portions have the same shape, the design can be facilitated and the optical characteristics of the first region can be stabilized. Since the multiple protrusions or recesses have the same shape, optical design and optical simulation can be performed more accurately, and stable and high-quality masters can be produced, so the difference in optical performance between the design and the actual product (Displacement) can be minimized. In particular, since the shapes are the same, generation of light other than diffracted light (stray light such as scattered light) can be suppressed, and a reduction in the saturation of the display color can be prevented.

  In addition, even if a plurality of convex portions or concave portions are regularly arranged in an arbitrary direction at a constant interval, there is an advantage that diffracted light with less stray light can be obtained due to the periodicity of the structure.

  When the plurality of convex portions or concave portions have the same shape and are regularly arranged at a constant interval in an arbitrary direction, a color with higher saturation can be obtained.

  On the other hand, there are the following advantages because the plurality of convex portions or concave portions arranged in the first region have different shapes, areas, or arrangement intervals.

  First, the plurality of convex portions have different shapes, areas, or arrangement intervals, so that a specific meaning can be given to the arrangement of the structures, such as arranging the structures having different shapes alternately. The convex portions or the concave portions each have a very small size of 5 μm or more and 50 μm or less, but when the magnification is observed using an optical microscope or the like, the arrangement of the structure can be seen. At that time, if the characteristic shape and arrangement only known by the party who manufactured the genuine product are provided in the first area, the authenticity of the counterfeit product is determined by reading that part. Can be done more strictly. Forgers need to counterfeit not only the visual similarity but also all the irregular shapes, which is effective in restraining the production of counterfeit products.

  Second, although the shape, area, or arrangement interval of the plurality of convex portions is different, the difficulty of production increases, but at the same time, counterfeiting becomes difficult.

  Thus, the forgery prevention effect of the display body or the article to which the display body is affixed can be further enhanced by the shape, area, or arrangement interval of the plurality of protrusions or recesses being different. FIG. 13 is an example of a first region in which a plurality of convex portions having different shapes, areas, and arrangement intervals are formed.

  When there are a plurality of first regions in the display body 10, a different color is displayed for each region by changing the height of the convex portion (or the depth of the concave portion) for each first region. be able to. That is, a display body capable of displaying a plurality of colors can be realized.

  On the other hand, by providing a plurality of convex portions (or concave portions having different depths) in one first region, the first region having a structure with a constant height (or depth) is provided. Colors that are difficult to realize and difficult to reproduce can be realized, and the forgery prevention effect of the display body can be further improved.

  As the shape of the convex portion or the concave portion that can be employed in the first region, a circle or a polygon having five or more vertices is more desirable. A circle or a polygon having many vertices exhibits a substantially uniform optical effect with respect to the azimuthal direction of the display body surface. Therefore, by forming these shapes in the first region, the same display color can be obtained relatively stably even when the direction of observing the display body or the position of the light source changes.

  In the first region, it is desirable that the area occupied by the convex portion or the concave portion is about 50%. From Equation 2, the diffraction efficiency is highest when the width of the convex portion or the concave portion (corresponding to the lattice line width L of Equation 2) is half of the pitch d. Therefore, the brightest display image can be obtained when the area occupied by the convex portion or the concave portion is about 50%.

(Explanation of the second area)
Next, the second area will be described.
The second region 25 is a region that is different in structure and optical properties from the first region 15. The second region 25 may have a concavo-convex structure different from that of the first region 15, or may be a flat surface on which no structure is formed. In addition, a plurality of second regions 25 may exist in the display body 10, or one may not exist.

  An example of a structure that can be used for the second region 25 is a diffraction grating. The diffraction grating is formed by repeatedly forming a linear concavo-convex structure (grating line) as shown in the perspective view of FIG. 11 and has a pitch of about 0.5 to 3 μm and a height of the structure of 0.1 to 0. 0. About 5 μm is a typical specification. The diffraction grating emits a rainbow-colored spectral color due to diffraction, and displays an image that changes in color and pattern according to the observation conditions such as the position of the light source and the observation angle of the observer, or displays a three-dimensional image Can do.

  Another structure that can be employed in the second region 25 is an antireflection structure. The antireflection structure is typically a conical structure 26 as shown in the perspective view of FIG. 14 or a pyramidal structure 27 arranged in an orderly manner, and the structure has a wavelength equal to or smaller than the wavelength of visible light ( For example, the higher the structure height is 300 μm or more, the higher the antireflection function is. The antireflection structure formed according to the specifications as described above has a function of preventing or reducing the reflection of incident visible light, and looks black or dark gray when observed.

  Further, as a structure that can be employed in the second region 25, a light scattering structure can be cited. As shown in the perspective view of FIG. 15, the light scattering structure is typically one in which a plurality of irregular shapes 27 having different sizes, shapes, and structure heights are irregularly arranged. The light incident on the light scattering structure is irregularly reflected in all directions and appears white or cloudy when observed.

  Further, the second region 25 may be a flat surface on which no concavo-convex structure is formed. When the second region 25 is a flat surface, the second region 25 looks like a mirror surface by the light reflecting layer 13.

  By combining the second region 25 and the first region 15, an image or design that can be visually observed can be displayed. A structure other than the structure described above may be formed in the second region.

(How to use the display)
The display body 10 described above can be used, for example, by sticking it to a printed matter or an article other than that through an adhesive or the like as an anti-counterfeit label. The display body 10 can display colors of a plurality of wavelengths in the front direction of the display body due to the fine uneven structure, and the colors change by changing the height of the structure, so that forgery is difficult. When this label is supported on an article, it is also difficult to forge or imitate the genuine article with label.

  FIG. 16 is a plan view schematically showing an example of a labeled article in which an anti-counterfeit label is supported on the article. 17 is a cross-sectional view of the labeled article shown in FIG. 16 taken along line IV-IV.

  16 and 17 illustrate a printed matter 100 as an example of a labeled article. This printed material 100 is an IC (integrated circuit) card and includes a base material 20. The base material 20 is made of plastic, for example. A concave portion is provided on one main surface of the substrate 20, and the IC chip 30 is fitted into the concave portion. Electrodes are provided on the surface of the IC chip 30, and information can be written to the IC and information recorded on the IC can be read through these electrodes. A printed layer 40 is formed on the substrate 20. The display body 10 mentioned above is being fixed to the surface in which the printing layer 40 of the base material 20 was formed through the adhesion layer, for example. For example, the display body 10 is prepared as an adhesive sticker or a transfer foil, and is fixed to the base material 20 by being attached to the printing layer 40.

  The printed material 100 includes a display body 10 having a fine uneven structure. Therefore, it is difficult to counterfeit or imitate the same printed product 100. Moreover, since the printed material 100 further includes the IC chip 30 and the printed layer 40 in addition to the display body 10, it is possible to adopt a forgery prevention measure using them.

  16 and 17 illustrate an IC card as a printed material including the display body 10, but the printed material including the display body 10 is not limited to this. For example, the printed matter including the display body 10 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 10 may be securities such as gift certificates and stock certificates. Alternatively, the printed matter including the display body 10 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 10 may be a package body that contains an article to be confirmed to be genuine or a part thereof.

  Moreover, in the printed material 100 shown in FIG.16 and FIG.17, although the display body 10 is affixed on the base material 20, the display body 10 can be supported on a base material by another method. For example, when paper is used as the base material, the display body 10 may be rolled into the paper and the paper may be opened at a position corresponding to the display body 10. Alternatively, when a light-transmitting material is used as the base material, the display body 10 may be embedded therein, or the display body 10 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 10 may be supported on an article that does not include a printed layer. For example, the display body 10 may be supported by a luxury product such as a work of art.

  The display body 10 may be used for purposes other than forgery prevention. For example, the display body 10 can be used as a toy, a learning material, or a decoration.

  The plurality of convex portions 16 are regularly arranged in the first region 15 so as not to contact each other. In FIG. 5, the diameter of the convex portion is about 10 μm. Further, the area occupied by the convex portion 16 in the first region 15 is about 50%, and the flat portion 17 in the first region 15 is about 50%. The height of the convex part 16 shall be 0.2 micrometer.

  Here, considering the directions indicated by the dotted lines A and B in FIG. 5, it can be considered that a diffraction structure having a pitch of about 14 μm is formed by the plurality of convex portions 16. Assuming that white illumination light is incident perpendicularly to the surface of the display body, for example, light having a wavelength of 630 nm is emitted as + 1st order diffracted light at an angle β≈2.58 ° according to Equation 1. Further, light having a wavelength of 540 nm has an angle of 2.21 °, and light having a wavelength of 460 nm has an angle of 1.88 °. Also in other directions (for example, dotted line C), diffracted light is emitted based on Equation 1 due to the periodicity of the plurality of convex portions 16. Thus, a diffraction structure with a sufficiently large pitch compared to the wavelength of the incident light takes a value close to the exit angle of the regular reflection light of the incident light (in this example, 0 °).

  Similarly, by using Equation 1 for + 2nd order diffracted light, the diffraction angle of each wavelength is 630 nm, the diffracted light is 5.16 °, 540 nm is 4.42 °, and 460 nm is 3 .77 °. These values are also close to the exit angle (0 ° in this example) of the regular reflection light of the incident light.

  As a result, when the display body of this example was observed, it was confirmed that light in which a plurality of wavelength components were mixed could be observed.

DESCRIPTION OF SYMBOLS 10 ... Display body, 11 ... Light transmission layer, 13 ... Reflection layer, 15 ... 1st area | region, 16 ... Projection part, 17 ... Flat part, 25 ... 2nd area | region, 26 ... Antireflection structure, 27 ... Light Scattering structure, 28 ... long side, 29 ... short side, 30 ... IC chip, 40 ... printed layer, 50 ... substrate, 100 ... printed material, 111 ... light transmissive substrate, 112 ... light transmissive resin layer, d ... Pitch of diffraction grating, DL ... + 1st order diffracted light, DL_r ... + 1st order diffracted light (red), DL_g ... + 1st order diffracted light (green), DL_b ... + 1st order diffracted light (blue), GR ... Diffraction grating, IL ... Illumination light, LS ... light source, NL ... normal, RL ... 0th-order diffracted light (regular reflection light), α ... incident angle, β ... exit angle, β_r ... exit angle of diffracted light of wavelength component R, β_g ... diffracted light of wavelength component G Emission angle, β_b: Emission angle of diffracted light of wavelength component B

Claims (9)

A light transmissive substrate;
A concavo-convex structure forming layer provided on one surface side of the substrate;
A display body comprising a reflective layer covering at least a part of the concavo-convex structure forming layer,
The concavo-convex structure forming layer includes a plurality of convex portions whose upper surface is substantially parallel to the base material surface, or a plurality of concave portions whose bottom surface is substantially parallel to the base material surface, and a flat portion substantially parallel to the base material surface. Is provided with at least one region configured and arranged,
The plurality of convex portions or concave portions have long sides and short sides of 5 μm or more and 50 μm or less,
The average arrangement interval between adjacent convex portions or concave portions is 5 μm or more and 50 μm or less,
The area occupied by the protrusions or recesses in the region is 20% or more and 80% or less,
The height of the convex part or the concave part is 0.1 μm or more and 0.5 μm or less,
The display body, wherein heights of the plurality of convex portions or concave portions are different for each region.   The display body according to claim 1, wherein heights of the plurality of convex portions or concave portions arranged in the region are different from each other.   The display body according to claim 1, wherein the plurality of convex portions or concave portions arranged in the region have the same shape and area.   The display body according to any one of claims 1 to 3, wherein a plurality of convex portions or concave portions arranged in the region are regularly arranged in an arbitrary direction at a constant interval. A plurality of projections or recesses of a height that is disposed in the area, or the shape or at least one of the surfaces product is displayed according to claim 1, characterized in that different respective projections or each recess, body. 6. The display body according to claim 5, wherein an arrangement interval between a convex portion or a concave portion arranged in the region and a peripheral convex portion or concave portion adjacent to the convex portion or concave portion is random at least in a part of the region. . Display body according to any one of claims 1 to 6, the shape of the projections or recesses, characterized in that a polygon having a circular or five or more vertices. Display body according to any one of claims 1 to 7, wherein the area occupied by the plurality of projections or recesses in the region is approximately 50%. A labeled article comprising the display according to any one of claims 1 to 8 and an article supporting the display.