JP2008275740A - Display body and laminate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a display body provided with a higher visual effect, hardly forged, facilitating authentication by obtaining characteristics with human eyes and a reading machine, and having a high eye-catch effect based on a new visual effect which can not be expressed by a conventional display body. <P>SOLUTION: The display body 10 is provided with a fine relief area 13 having a fine relief structure 14. In the fine relief area 13, a visible light reflectance of the display body is low and primary diffracted light is emitted. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a display body and a laminated body including the display body, and more particularly to a display body and a laminated body suitable for security applications.

  Conventionally, as a means for preventing counterfeiting, a fine structure or color tone change that cannot be easily imitated, or an optical phenomenon that is only in combination with another optical functional film as a discriminator is observed. Various aspects have been put into practical use with the advancement of technology, such as a configuration in which a certain pattern or the like can be read only by a dedicated reader.

Among them, a hologram and a diffraction grating image are given as one of the most utilized because of practical ease of operation.
A hologram is produced by providing a fine concavo-convex pattern and a refractive index distribution by an optical photographing method such as two-beam interference. On the other hand, the diffraction grating image is produced using a pixel in which a diffraction grating is arranged in a minute area.
Both holograms and diffraction grating images are difficult to counterfeit, difficult to copy with color copiers, etc., and are excellent in design, so they are widely used for credit cards, ID cards, various securities, certificates, etc. ing.
However, in actual operation, the authenticity of holograms and diffraction grating images is left to the human eye, so even if it is a microscopically fake product, all people can accurately and accurately authenticate with the naked eye. It is not easy to make a false determination.

Further, as the holograms and diffraction grating images as described above are distributed and popularized, the forgery technique is also advanced, so that a display body that is more difficult to forge is being demanded.
For example, a hologram or diffraction grating having a surface relief structure may be duplicated by contact exposure.
In order to prevent forgery, for example, Patent Document 1 describes that a fine pattern having a diffraction effect is devised. In this security device, information cannot be read by human eyes, making it difficult to understand the presence or absence of security information. Therefore, it is difficult to determine whether or not the product is genuine, and a reading machine is used for the determination.
In addition, the accuracy of holograms and diffraction gratings replicated by the contact exposure method can be confirmed to be reduced compared to the original. However, since normally replicated products are distributed only as replicated products, they are genuine for non-professional general consumers. There was a problem that it was difficult to judge whether the product was a product.

<Prior art>
It is known that a substrate provided with fine irregularities suppresses reflection of incident light. For example, some types of anti-reflection films give fine distribution of the refractive index of the film by embossing fine irregularities on the surface of the film base material, or by mixing a filler into the film forming resin itself. Unevenness is formed. In recent years, it has been disclosed that the unevenness can be made finer and the period of the protrusions can be made equal to or less than the wavelength of light, thereby preventing reflection of light and controlling incident light (see, for example, Patent Document 2). In this technique, the period of the protrusions is set to be equal to or less than the wavelength of light, particularly about 50 to 250 nm, so that reflection of light is suppressed and applied to the light control sheet. However, as in the present invention, a fine convex portion is provided at a center-to-center distance equal to or less than the wavelength of light, and a reflective layer is provided on this to provide a display body that can control diffracted light and observe diffracted light. Is not yet known.
JP-T-2002-505774 JP 2007-48688 A

  The present invention aims to solve the above problems. That is, the first object of the present invention is to provide a display body that has a higher visual effect and is difficult to counterfeit. A second object of the present invention is to provide a display body that can easily recognize the characteristics of human eyes and a reading machine and can easily determine the authenticity. A third object of the present invention is to provide a display body having a high eye-catching effect due to a novel visual effect that cannot be expressed by a conventional display body.

  A first aspect of the present invention is a display body having a fine relief region having a fine relief structure, wherein the fine relief region has low visible light reflectance and emits first-order diffracted light. It is the display body characterized by this. By this configuration, it is not a metallic luster when viewed from the front direction, it looks like a dull printed surface, and it is not known that it is an optical element that can confirm diffracted light. Become. In addition, since it is possible to observe the diffracted light when tilted, it is easy to determine the authenticity with both human eyes and machines. In addition, when viewed from the front direction, the fine relief area can be expressed as black or gray with no gloss and low brightness and saturation as if it were a printed surface, and thus a design different from the conventional security pattern is possible.

In addition to the above structure, the fine relief structure of the display body of the present invention includes a reflective layer.
Further, the thickness of the reflective layer (t) satisfies the following formula.
t> 1 / α,
α = 4πk / λ _min
k: extinction coefficient, α: absorption coefficient, λ _min : shortest wavelength in the visible light region Further, the reflective layer is a metal. By adopting such a configuration, transmission of light is prevented, and the image appears black when observed from the normal direction. Moreover, the diffracted light can be strengthened.
In addition to the above structure, the visible light reflectance of the fine relief region is 10% or less. By adopting such a configuration, it looks almost black when viewed from the normal direction, and it is easy to distinguish from a conventional security pattern.

  Furthermore, in addition to the above configuration, the display body of the present invention is characterized in that the first-order diffracted light emitted from the fine relief region includes only a part of the visible light wavelength range. Further, the first-order diffracted light emitted from the fine relief region does not include a wavelength longer than 700 nm. By adopting such a configuration, the observable wavelength is different from that of a conventional hologram or diffraction grating, and a visual effect different from the conventional one can be obtained.

Furthermore, in addition to the above configuration, the display body of the present invention includes a fine relief non-formation region not having a fine relief structure, and the visible light reflectance of the fine relief non-formation region is 60% or more.
In addition to the above structure, the display body includes a diffraction grating region having a diffraction grating structure, the visible light reflectance of the diffraction grating region is 60% or more, and emits diffracted light.
By making the display body provided with a region having a high visible light reflectance at the same time, a difference in visible light reflectance can be relatively observed, so that it is easy to determine an authentic product. In addition, the variety of design choices makes the decoration effect great and attracts attention.

  Furthermore, the 2nd aspect of this invention is a laminated body provided with such a display body and the base material which has arrange | positioned the said display body. The laminate of the present invention can be used for various authentication applications such as ID cards and quality assurance seals. Moreover, it can use suitably also for the use as which a designability is calculated | required, such as a card | curd, a seal | sticker, a book, and product packaging.

  According to this invention, it can be set as the display body and laminated body which are provided with a more advanced visual effect and are hard to forge. In addition, it is possible to obtain a display body and a laminated body that are easy to determine the authenticity by grasping the characteristics by human vision or by a reading machine. Furthermore, a novel visual effect that cannot be expressed by a conventional hologram or diffraction grating can provide a display body and a laminated body having high design properties and a high eye-catching effect.

Hereinafter, the present invention will be specifically described with reference to the drawings.
1 to 6 are diagrams for explaining a first aspect of the present invention.
7 and 8 are diagrams illustrating the second aspect of the present invention.
FIG. 1 is a cross-sectional view schematically showing a first embodiment of a display body of the present invention.
In the first embodiment of the present invention, the display body 10 includes a first base material 11, a reflective layer 12, and a second base material 18. In addition, the display body 10 includes a fine relief region 13. The fine relief region has a fine relief structure 14. The fine relief structure 14 is located at the interface between the first base material 11 and the second base material 18 and includes a reflective layer 12 having a shape along the fine relief.

<First base material / second base material>
The first base material 11 and / or the second base material 18 are layers for holding the fine relief structure 14 constituting the fine relief region 13. Examples of the material of the first base material 11 and the second base material 18 include thermoplastic or photo-curable resins. For example, when a thermoplastic resin or a photo-curing resin is used, the first substrate 11 or the second substrate 18 having a concave structure and / or a convex structure on one main surface can be easily transferred by transfer using an original plate. Can be formed. The first base material 11 and the second base material 18 may use the same material. By using a light-transmitting material, it can be observed as a display element through each base material. Each of the first base material 11 and the second base material 18 may be a laminate of a plurality of types of resins. Further, one of the first base material 11 and the second base material 18 can be omitted. Or in order to arrange | position the display body of this invention to another base material and to use it as a laminated body, any one can also be made into an adhesive layer.

<Fine relief structure>
The fine relief structure 14 can be formed by, for example, a method of drawing a pattern with an electron beam on a photosensitive resin material. Alternatively, it is formed by the so-called hot embossing method in which a master plate with fine irregularities corresponding to fine irregularities is pressed against a thermoplastic resin laminated on a film, for example, as in the production of a surface relief hologram can do.

It is also possible to apply a UV curable resin to a transparent substrate such as a film, press the original plate against it, and then irradiate ultraviolet rays from the substrate side to cure the UV curable resin and then remove the original plate. The first base material 11 or the second base material 18 provided with the relief structure 14 can be obtained. At this time, a diffraction grating structure 17 described later can be formed together.
An original plate with fine irregularities can be obtained, for example, by a method in which a resin in which a hologram pattern is recorded using a two-beam interference method, a resin in which a pattern is drawn by an electron beam is used as a matrix, or a metal is cut by a cutting tool. It can be obtained by electroforming the mother die obtained.
Here, the fine relief structures 14 forming the fine relief regions 13 do not necessarily have the same size and shape as long as the regularity of the arrangement is maintained. Further, the cross-sectional shape is not particularly limited as long as it exhibits the above-described effect of reducing the reflectance with respect to visible light.

FIG. 3 is an enlarged perspective view showing an example of a pattern that can be selected as the fine relief structure 14. FIG. 3A shows a case where the convex portion 31 has a shape in which cones are arranged. FIG. 3B is a schematic diagram showing the case where FIG. 3A is viewed from the back side.
The height of the convex portion (depth of the concave portion) h should be ½ or more of the center-to-center distance, and is typically 0.3 μm or more and 0.5 μm or less.

Examples of the shape of the convex portion that can be selected as the fine relief structure include a pyramid including a pyramid and a cone, a frustum including a pyramid and a truncated cone, a pillar, a hemisphere, a semi-ellipsoid, and the like. Any shape may be used as long as the cross-sectional area decreases continuously or stepwise from the base end to the top. The effect of the present invention can be obtained even if the top of the convex portion is not sharp, such as a truncated cone. The shape of the convex portion is preferably a cone or a frustum because the horizontal cross-sectional area continuously changes.
The arrangement of the convex portions is preferably regular. For example, they may be arranged in a matrix, and it is particularly preferable to select an arrangement method that can be arranged most densely in accordance with the cross-sectional shape in the horizontal direction of the protrusion base end. In particular, it is preferable that the base end portion of the convex portion is formed in contact with the adjacent convex portion without leaving an interval. FIG. 4 illustrates some selectable sequences. Even if the regularity is partially broken, it is possible to obtain the configuration of the display body of the present invention that suppresses regular reflection to some extent and emits diffracted light.
When the fine relief structure 14 is a set of a plurality of convex portions as shown in FIG. 3, the display body is configured such that the base end side is the observer side and the observer side has a hole. Then, the deformation | transformation and damage of a convex-part top part can be prevented, and it is preferable.

<Reflective layer>
As the reflective layer 12, a metal film that does not transmit visible light and has a high visible light reflectivity, for example, a metal material such as aluminum, silver, and alloys thereof can be used. In this case, when the fine relief region 13 is observed from the normal direction, it looks black or gray achromatic.
Further, since the reflective layer 12 is made of a metal film, the difference in reflectance between the fine relief region 13 and the fine relief non-formation region 15 described later becomes clear, so that each region is recognized visually or by a reading machine. It becomes easy to do.

In particular, it is desirable to set the film thickness (t) of the metal reflective film so as to satisfy the following formula.
t> 1 / α,
α = 4πk / λ _min
k: extinction coefficient, α: absorption coefficient, λ _min : shortest wavelength in the visible light range Each of the metal and its compound exhibits intrinsic light absorption, but almost all of the visible light range is satisfied as long as the above film thickness conditions are satisfied. A high reflectivity can be obtained. For example, in the case of aluminum, if the shortest wavelength in the visible light region is 380 nm, the extinction coefficient k is about 4.6, and the film thickness may be 6 to 7 nm or more from the above formula.

It should be noted here that the apparent film thickness of the metal reflective film varies depending on the viewing angle. In particular, when the metal reflective film is formed on the fine relief structure 14, as shown in FIG. 4, the thickness (t ₁ ) of the reflective layer 12 when observed from the normal direction to the display body of the present invention, The film thickness when observed from the direction is different. In order to obtain a sufficient effect, it is desirable that the film thickness (t _min ) in the direction perpendicular to the tangent of the outline forming the fine relief structure satisfy the above equation.

The reflective layer can be formed by a thin film forming method such as vapor deposition or sputtering (FIG. 6A). The reflective layer 12 may be on the observer side or the back side with respect to the fine relief structure 14 as long as it follows the shape of the fine relief structure 14.
Alternatively, in addition to the reflective layer 12, a laminate of dielectric layers having different refractive indexes between adjacent ones, that is, a dielectric multilayer film may be provided. If a multilayer dielectric film is used, wavelength selectivity can be imparted to the fine relief region 13, so that a visual effect different from that obtained when a metal or single-layer dielectric film is used as a reflective layer can be obtained.
For example, the multilayer dielectric film 61 alternately deposits a high refractive index material 62 such as zinc sulfide and a low refractive index material 63 such as magnesium fluoride on the first base material 11 on which the fine relief structure 14 is formed. Can be obtained. At this time, as shown in FIGS. 6B and 6C, the metal film 65 may be on the first base material 11 side or the second base material 18 side.

The reflective layer provided in the fine relief structure is preferably a reflective layer having a visible light reflectance of 60% or more when a smooth surface (a surface on which the fine relief structure is not formed) is formed. When the visible light reflectance is 60% or more, the transmission of incident light is prevented, and the image appears black when observed from the normal direction. In addition, strong diffracted light can be observed.
When the display body of the present invention includes the fine relief non-formation region 15, a reflective layer can be provided also in the fine relief non-formation region. The reflective layer at this time is also preferably a reflective layer having a visible light reflectance of 60% or more, more preferably the same reflective layer provided in the fine relief region can be provided at the same time. With such a configuration, when the display body of the present invention is observed from the normal direction, the fine relief region 13 has a dull black or gray, and the fine relief non-formation region 15 has strong reflected light and metallic luster. It can be observed, and the difference between each region becomes remarkable. In particular, when the fine relief non-formation region 15 is the diffraction grating region 16 provided with the diffraction grating structure 17, this effect is even more remarkable because diffracted light can be observed in addition to the regular reflection light in the direction close to the front. Yes, high designability can be obtained.

  The display element of the present invention is manufactured, for example, by providing the first base material 11 with the fine relief structure 14, forming the reflective layer 12 covering the fine relief structure 14, and forming the second base material 18 thereon. can do. For example, a laminated body in which an embossed layer having a thickness of 1 μm is provided on a light-transmitting film having a thickness of 100 μm as the first substrate 11, a fine relief structure 14 is provided on the embossed layer, and a reflective layer 12 having a thickness of 100 nm is formed by aluminum vapor deposition. Provide. Thereafter, the second substrate 18 can be formed by laminating a resin film on the reflective layer 12 via an adhesive. Moreover, if the second substrate is a laminate of an adhesive material and release paper, the display body of the present invention can be used as a seal.

<Fine relief non-formation area>
The display body 10 further includes a fine relief non-formation region 15. FIG. 1 shows a case where the fine relief non-formation region 15 is a diffraction grating region 16 having a diffraction grating structure 17. The diffraction grating structure also includes a reflective layer as in the fine relief structure.
The diffraction grating structure 17 constituting the diffraction grating region 16 is provided with a reflective layer in an assembly in which linear or curved protrusions or grooves are arranged in parallel at a distance d of about the wavelength of visible light or more. For example, when white light is used as incident light, the first-order diffracted light appears mainly at different angles for each wavelength. Moreover, the diffraction grating area | region 16 is visually recognized as a silver white area | region provided with metallic luster in the angle which cannot observe diffracted light.
In the diffraction grating region 16, a desired color image is obtained by appropriately setting the spatial frequency, azimuth angle, diffraction efficiency, depth, height, etc. of the diffraction grating structure to be configured for each minute area in the region. be able to. In addition, by appropriately setting the material and configuration of the reflective layer, desired visual effects such as wavelength selectivity and visibility / invisibility of the lower layer can be obtained.

<Visual effects of display>
The visual effect of the display body 10 will be described in more detail.
First, the visual effect resulting from the diffraction grating structure 17 which is a normal diffraction grating will be described.

  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 most representative diffracted light is first-order diffracted light. The emission angle β of the first-order diffracted light can be calculated from the following equation (1) when the light travels in a plane perpendicular to the grating line of the diffraction grating.
d = λ / (sin α−sin β) (1)
In equation (1), d represents the grating constant of the diffraction grating, 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 the incident angle is symmetric with respect to the Z axis (in the case of a reflective diffraction grating). For α and β, the clockwise direction from the Z axis is the positive direction.

  As is apparent from equation (1), the exit angle β of the first-order diffracted light changes according to the wavelength λ. That is, the diffraction grating has a function as a spectroscope. Accordingly, when the illumination light is white light, the color perceived by the observer changes when the observation angle is changed in a plane perpendicular to the grating line of the diffraction grating.

In addition, the color perceived by the observer under a certain observation condition changes according to the lattice constant d.
As an example, it is assumed that the diffraction grating emits first-order diffracted light in the normal direction. That is, the exit angle β of the first-order diffracted light is assumed to be 0 °. Assume that the observer perceives this first-order diffracted light. If the emission angle of the 0th-order diffracted light at this time is αN, equation (1) can be simplified to equation (2) below.

d = λ / sin αN (2)
As is clear from equation (2), in order for the observer to perceive a specific color, the wavelength λ corresponding to the color, the incident angle | αN | of the illumination light, and the lattice constant d are equal to each other. What is necessary is just to set so that the relationship shown in (2) may be satisfied. For example, white light including all light components having a wavelength in the range of 400 nm to 700 nm is used as illumination light, and the incident angle | αN | of the illumination light is set to 45 °. It is assumed that a diffraction grating having a spatial frequency (reciprocal of the grating constant) distributed within a range of 1000 / mm to 1800 / mm is used. In this case, when the diffraction grating is observed from the normal direction, a portion with a spatial frequency of about 1600 lines / mm looks blue, and a portion with a spatial frequency of about 1100 lines / mm looks red.

  Note that the diffraction grating is easier to form when the spatial frequency is smaller. Therefore, in a normal display body, the majority of diffraction gratings are diffraction gratings having a spatial frequency of 500 lines / mm to 1600 lines / mm.

  As described above, the color perceived by the observer under a certain observation condition can be controlled by the grating constant d (or spatial frequency) of the diffraction grating. When the observation angle is changed from the previous observation condition, the color perceived by the observer changes.

Next, the visual effect resulting from the fine relief structure 14 will be described.
FIG. 2A is a diagram schematically showing how the diffraction grating structure emits diffracted light. FIG. 2B is a diagram schematically illustrating how the fine relief structure emits diffracted light. 2 (a) and 2 (b), 21a and 21b indicate illumination light, 22a and 22b indicate regular reflection light or zero-order diffracted light, and 23a and 23b indicate first-order diffracted light.

  As described above, the plurality of concave portions 32 or convex portions 31 provided in the fine relief structure 14 has a smaller center distance than the minimum center distance of the grooves provided in the diffraction grating structure, that is, the lattice constant of the diffraction grating. They are arranged two-dimensionally with w. For this reason, even if the concave portions 32 or the convex portions 31 are regularly arranged and the fine relief structure 14 emits the diffracted light 23b, the observer can observe the diffracted light 23b and the diffraction grating structure 17 having the same wavelength. The diffracted light 23a is not perceived at the same time. If the difference between the grating constant d of the diffraction grating and the distance w between the centers of the concave or convex portions is sufficiently large, the observer can observe the diffracted light 23a from the diffraction grating structure 17 and the fine relief regardless of the wavelength. The diffracted light 23b from the structure 14 is not perceived at the same time. That is, in this case, the observer does not visually recognize the diffracted light 23b from the fine relief structure 14 within an observation angle range in which the diffracted light 23a from the diffraction grating structure 17 can be visually recognized.

  Moreover, each recessed part 32 or the convex part 31 has a forward taper shape. Therefore, the reflectance of the regular reflection light of the fine relief structure 14 is small no matter what angle is observed.

  Therefore, for example, when the display 10 is observed from the normal direction, the fine relief region 13 looks darker than the diffraction grating region 16 including the diffraction grating structure 17. In this case, typically, the fine relief region 13 appears black. Here, “black” refers to the reflectance for all light components having a wavelength in the range of 400 nm to 700 nm when the intensity of specular reflection light is measured based on a visible light reflectance measurement method described later. Means 10% or less. Therefore, the fine relief region 13 looks like a black printed layer formed so as to overlap with a part of the diffraction grating in the display body shown in FIG. 1, for example.

  Further, if the emission angle of the first-order diffracted light 23b from the fine relief structure 14 is larger than −90 °, the observer can set a fine relief by appropriately setting the angle formed by the normal direction of the display body 10 and the observation direction. The first-order diffracted light 23b from the structure 14 can be perceived. Therefore, in this case, it can be visually confirmed that the fine relief structure 14 is different from the black printed layer.

When this configuration is adopted, the distance (center-to-center distance) w between the center of a certain convex portion and the center of the convex portion closest thereto is preferably equal to or less than the visible light wavelength, and is preferably 400 nm or less, more preferably 350 nm. It is as follows. In such a case, as is clear from the above equation (2), the fine relief structure 14 has a long wavelength region (for example, red to yellow) in the diffracted light of visible light even if the incident angle α of the incident light is changed. Theoretically diffracted light is emitted below the plane of the display element. That is, diffracted light having a wavelength corresponding to the long wavelength region near red is not emitted. On the other hand, only diffracted light in a short wavelength region (for example, purple to green) can be emitted above the plane. Therefore, diffracted light in a narrow wavelength range can be observed by observing from an angle close to the plane formed by the display element, which is inclined more than the viewing angle of a normal micron-order hologram or diffraction grating image.
Further, as is clear from the above formula (1), a certain wavelength region (for example, a green region having a wavelength of 520 to 570 nm) with respect to a certain incident light angle to the fine relief region 13 included in the display body of the present invention. Since the diffracted light emission angle range is theoretically wider than that of ordinary holograms and diffraction grating images, diffracted light close to a single color tone can be observed.

  The center distance w is preferably 200 nm or more. If it is smaller than this range, all the diffracted light in the visible region has an emission angle of 90 degrees or more, which is below the plane of the display element, so that no so-called visible light is emitted and the diffracted light can be confirmed visually with the naked eye. It will disappear. In order to confirm well with the naked eye, it is preferably larger than 250 nm. In the case of machine reading, since a light beam having a wavelength below the visible region can be confirmed within a range that can be detected by a light receiving element such as a CCD, the center-to-center distance can be further reduced according to the purpose.

  On the other hand, since the diffraction grating structure 17 is 1600 lines / mm even if the spatial frequency is large, the wavelength corresponding to red when the incident angle α of the incident light exceeds about 20 degrees, as is clear from the equation (1). And diffracted light of all wavelengths in the visible region. Therefore, in this case, it is easier to confirm that the display body 10 is genuine as compared with the case where the diffraction grating structure 17 emits diffracted light having a wavelength corresponding to red.

  When the fine relief structure 14 is formed by arranging a plurality of pixels, the shape, depth or height of the concave portion 32 or the convex portion 31, the average center distance, If at least one of the arrangement patterns is made different, the appearance of the diffracted light from these pixels can be made different. Therefore, by utilizing this, gradation display can be performed with the fine relief structure 14.

  As an example of the second aspect of the present invention, FIG. 7 shows a display of the present invention that includes a fine relief region 13 that is observed as black during frontal observation and a fine relief non-formation region 15 that includes a diffraction grating region 16. The top view in which the body 70 is laminated | stacked on the base material (not shown) and comprises the laminated body 75 is shown. The display body 70 does not cover the entire upper surface of the substrate, and a light absorption region 72 by printing is formed in the gap. In the laminated body 75, two types of images, ie, a grating image with a black background (image by a diffraction grating) and an image formed in the light absorption region 72 are observed during frontal observation. Here, the background of the grating image is a fine relief region 13. Of course, when the light-absorbing area 72 is printed in a black color similar to the color of the fine relief area 13 when viewed from the front, the fine relief area 13 and the light-absorbing area 72 are against human eyes. It will be perceived almost equally and only the grating image will be observed.

On the other hand, during oblique observation, a color mainly due to light diffraction in the fine relief region 13 is observed. Under this condition, since the observation angle is too large, the diffracted light cannot be observed in the diffraction grating region 16.
That is, in the laminated body 75 according to the present invention as illustrated in FIG. 7, three kinds of unique color changes that differ depending on the observation angle can be simultaneously realized in the same plane.

  Although the fine relief structure 14 included in the fine relief region 13 constituting the display body of the present invention includes the reflective layer 12, the regular reflection of visible light is kept low and the scattering of visible light is also kept low. Therefore, when the fine relief area is irradiated with white light and observed from the normal direction of the display body, reflection and scattering are suppressed, and the area is observed as a black or gray area with no gloss and low brightness and saturation. And the fine relief area | region 13 and the fine relief non-formation area | region 15 are provided with the combination which each differs about the visible light reflectance, the presence or absence of diffracted light, the visual recognition angle area | region of a diffracted light, and a wavelength. Therefore, if the pattern is such that it can be recognized by the naked eye or a machine reading device based on these differences, even if there is a counterfeit product, it can be immediately determined.

  While the size of the grating pattern provided in a general diffraction grating or hologram image is on the order of microns, the fine relief structure provided in the display of the present invention is very fine, and therefore it can be said that replication is difficult compared to conventional techniques. .

<Visible light reflectance>
The visible light described in the present invention is similar to the visible radiation defined in JIS Z 8113 (1998), and refers to radiation that can cause visual sensation immediately after entering the human eye.
The visible light reflectance or simply reflectance described in the present invention is a measurement of 20-degree specular gloss, and indicates the maximum ratio of the specularly reflected light flux to the incident light flux in the entire visible light wavelength band. Is. In this specification, the wavelength of the visible light wavelength region is set to 400 nm to 700 nm, and the value of the wavelength having the maximum value is used for the 20-degree specular gloss calculated by measurement using the UV-3101PC type manufactured by Shimadzu Corporation.

  In the fine relief region provided in the display body of the present invention, the visible light reflectance is very low, 10% or less, even though the fine relief structure has a reflective layer. Therefore, it can be confirmed at a glance that it is greatly different from a hologram or the like produced with a normal size grating pattern. At this time, even if the first base material 11 provided on the observation surface side is a general transparent material (for example, an acrylic resin), the reflectance due to this is also several percent. You can safely ignore the rate measurement. Moreover, there is little light scattering. Therefore, when the display body of the present invention is irradiated with white light and the fine relief area is observed from the normal direction of the display body, the brightness is low and the black or gray color is achromatic.

  In this way, the display body of the present invention can be set so that the diffracted light cannot be confirmed unless observed from a direction that is considerably inclined as compared with a normal hologram or diffraction grating. It is difficult to counterfeit because it is unaware of its existence. On the other hand, for those who have knowledge about the properties of the display body of the present invention, it can be easily discriminated whether visually or with a reading machine.

  In addition, the fine relief structure of the fine relief region provided in the display body of the present invention has a center-to-center distance of the concave or convex portions smaller than that of the visible wavelength region, and the diffracted light emission angle depends on the relief shape and pattern density. , Adjusted to suppress reflection and scattering of incident light. Therefore, even if an object noticed to be the display body of the present invention is to be copied, light is scattered in copying (contact exposure method) that does not use the original plate, and becomes whitish when viewed from the front. Since human vision is more sensitive to lightness of achromatic color than diffracted light, it is easy to notice abnormalities when it is not a genuine product and can easily determine authenticity. If a reading machine is used, authenticity can be compared with specific brightness, so that authenticity can be determined more easily.

  Further, the display body of the present invention is a black having low gloss and low brightness and saturation as if the fine relief area of the display body is a printed surface at an angle where diffracted light cannot be confirmed, particularly in the front direction. Alternatively, since gray can be expressed, a visual effect and a design that are not found in other display bodies such as a conventional hologram and diffraction grating can be obtained by itself. Further, by combining with a conventional optical display having a known optical effect such as a hologram or a diffraction grating, it is possible to obtain a display that is more easily noticed by human eyes and remains in the impression (high eye catching power).

  As another embodiment of the second aspect of the present invention, FIG. 8 shows an example in which a display body 82 of the present invention is disposed on a plastic substrate 81 to form a laminate 80. As the display body 82, not only the first to fourth embodiments can be selected, but also a display body with a combination other than this can be freely selected. As the base material 81, it is only necessary to hold the display body, and paper, plastic card, film, or the like can be selected according to the use of the laminate. For example, a pressure-sensitive adhesive or an adhesive can be provided as a bonding layer on the display body side or the base material side, and the display body can be arranged at an arbitrary position on the base material through this.

  Since the present invention has an unprecedented visual effect and is difficult to counterfeit, in addition to security applications such as anti-counterfeiting, certification, etc., it has a high design, so it can be used as a decoration card for play cards, postcards, product packaging, books It can also be used together with printed matter such as.

1 schematically shows a part of a cross section of a display body according to the present invention. It is explanatory drawing which shows the behavior of the light which injected into the display body which concerns on this invention. (A) It is sectional drawing which shows a mode that a diffraction grating structure inject | emits a diffracted light schematically. (B) It is sectional drawing which shows a mode that a fine relief structure inject | emits a diffracted light. It is a perspective view which expands and shows an example of the fine relief structure with which the display body of this invention is provided. (A) It is the perspective view seen from the convex part side. (B) It is the perspective view seen from the recessed part side. It is explanatory drawing which illustrates the arrangement | sequence of the fine relief structure which the display body of this invention can be equipped. 1 schematically shows a partially enlarged cross section of a relief structure forming region of a display body according to the present invention. 1 schematically shows a part of a cross section of a display body according to the present invention. 1 schematically shows an embodiment of a laminate according to the present invention. The other form of the laminated body which concerns on this invention is shown roughly.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10, 70, 82: Display body 11: 1st base material 12: Reflective layer 13: Fine relief area | region 14: Fine relief structure 15: Fine relief non-formation area | region 16: Diffraction grating area 17: Diffraction grating structure 18: Second group Materials 21a, 21b: Illumination light 22a: Regular reflection light 22b: 0th order diffracted light 23a, 23b: 1st order diffracted light 31: Convex part 32: Concave part 61: Multilayer dielectric film 62: High refractive index material 63: Low refractive index material 65 : Metal film 72: Light absorption region 75, 80: Laminate 81: Base material

Claims (10)

  A display body comprising a fine relief region having a fine relief structure, wherein the fine relief region has a low visible light reflectance and emits first-order diffracted light.   The display body according to claim 1, wherein the fine relief structure includes a reflective layer. The display body according to claim 2, wherein the reflective layer has a thickness (t) satisfying the following formula.
t> 1 / α,
α = 4πk / λ _min
k: extinction coefficient, α: absorption coefficient, λ _min : shortest wavelength in the visible light region   4. The display body according to claim 2, wherein the reflective layer is a metal.   The display body according to claim 1, wherein the visible light reflectance of the fine relief region is 10% or less.   6. The display body according to claim 1, wherein the first-order diffracted light emitted from the fine relief region includes only a part of the visible light wavelength range.   The display body according to claim 6, wherein the first-order diffracted light emitted from the fine relief region does not include a wavelength longer than 700 nm.   The fine relief non-formation area | region which does not have a fine relief structure is provided in addition to the said fine relief area | region, The visible light reflectance of the said fine relief non-formation area | region is 60% or more, It is characterized by the above-mentioned. The display in any one.   A diffraction grating region having a diffraction grating structure is provided in addition to the fine relief region, the visible light reflectance of the diffraction grating region is 60% or more, and the first-order diffracted light is emitted. The display body according to any one of 8.   A laminate comprising the display body according to any one of claims 1 to 9 and a base material on which the display body is disposed.