JP5909856B2 - Display and labeled goods - Google Patents

Description

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

  In recent years, there has been an increasing demand for applying anti-counterfeiting technology for proving authenticity to securities such as gift certificates and credit cards, or generally expensive items such as branded items and luxury items. Such anti-counterfeiting technology can be broadly divided into two types. One is an overt technique in which a general user can recognize that the anti-counterfeiting technology is applied only by observing the appearance with the naked eye, and can determine the authenticity. The other is a covert technique in which only a specific user knows the existence of a forgery prevention technique and can confirm that the forgery prevention technique has been applied by performing some special verification to determine whether the forgery prevention technique is applied.

  As the overt technique, for example, OVD [Optical (ly) Variable Device] is used. As OVD, for example, holograms and diffraction gratings that can express stereoscopic images and decorative images that cause special color changes using interference or dispersion of reflected light, and thin films with different optical properties are stacked in multiple layers There is a multilayer thin film that has a structure and causes a change in display color (color shift) with a change in viewing angle. A synonym for OVD is DOVID [Differential Optical (ly) Variable Imaging Device].

  OVD has features such as requiring advanced manufacturing technology, providing unique visual effects, and being able to judge authenticity with a glance. Credit cards, securities, and certifications are effective anti-counterfeiting measures. It is formed on the entire surface of a document or a part thereof. Recently, OVD is affixed to articles other than securities, for example, electrical products such as sporting goods and computer parts, and recording media on which software is recorded or its package to prove the authenticity of the product. It has come to be widely used as an authentication sticker or seal sticker.

  In addition, as described above, OVD is generally a forgery prevention means that is difficult to elaborate and is easy to confirm that it is a genuine product. However, OVD is applied to paper media such as gift certificates, banknotes, passports, and stock certificates. In many cases, the OVD is used in the form of a transfer foil which is more difficult to replace the OVD than the adhesive label. When the OVD thermally transferred from the support of the transfer foil onto the article is peeled off from the article, the optical thin film contained in the OVD is physically destroyed, and the original visual effect is impaired. Therefore, unauthorized use of the OVD due to rewriting or tampering can be prevented.

  Examples of the covert technique include fluorescent printing, line latent image, polarized latent image, and specific wavelength absorption printing. These still play an important role in preventing counterfeiting.

  A typical example of fluorescent printing is fluorescent printing in which a printing ink containing a phosphor that is excited by ultraviolet rays and emits visible fluorescence is printed. The phosphor contained in the printing ink is difficult to visually recognize under a normal visible light source and emits fluorescence in the visible region when irradiated with ultraviolet rays. The wavelength of this ultraviolet light can be variously selected according to the type of phosphor used. In general, black light that emits ultraviolet light having a wavelength of 365 nm is used. As a recent technique related to fluorescent printing, for example, there is a technique that makes it difficult to reproduce color for those who try to cheat by mixing two or more phosphors (for example, see Patent Document 1).

  A typical example of a line latent image is line latent image printing using intaglio printing. In multiline latent image printing, a plurality of thin lines each having a length direction equal to each other, a plurality of patterns having different length directions from each other, each thin line having several tens of microns, and the preceding pattern are adjacent to each other To be formed. When the line widths are formed with the same line width and pitch, it is difficult to distinguish the patterns from each other when observed from a direction perpendicular to the surface on which the patterns are formed. When observed from a direction perpendicular to the fine line of a certain pattern and inclined with respect to the surface on which the pattern is formed, the apparent density of the fine line is higher in the previous pattern than in the other patterns. Become. In this way, the latent image is visualized. According to the line latent image, for example, the width and density of fine lines in a certain pattern are set to be higher than the resolution of the copying machine, and the width and density of thin lines in other patterns are set to be lower than the resolution of the copying machine. Even if these patterns cannot be distinguished from each other when observed with the naked eye, those patterns obtained using a copying machine such as an electrophotographic apparatus can distinguish the previous patterns from each other by observation with the naked eye. Recent technologies related to line latent images include, for example, the addition of functions by mixing fluorescent pigments with ink, and the enhancement of copy restraint by performing more precise and fine printing (for example, patent documents). 2).

  A typical example of a polarization latent image is one using liquid crystal. Liquid crystal materials are mainly used in liquid crystal displays. With the recent increase in demand for liquid crystal displays, various advanced polarization technologies have been developed, and these polarization technologies have begun to be applied in various forms as covert technologies in anti-counterfeiting devices. For example, there is a display body in which a latent image visualized by observing through a polarizer is recorded using a birefringence of a nematic liquid crystal or a plastic film having a birefringence (for example, a patent document). 3 and Patent Document 4).

Japanese Patent Laid-Open No. 10-250214 JP 11-291609 A JP 2005-091786 A Japanese translation of PCT publication No. 2002-530687

  In the anti-fake image prevention technique for forming a polarization latent image using liquid crystal, the anti-counterfeiting effect is enhanced by improving the polarization characteristics and improving the precision and definition of the pattern. However, when liquid crystal is used, the cost becomes high.

  An object of the present invention is to provide a display technology capable of forming a polarization latent image without using a liquid crystal.

The first aspect of the present invention has a light-transmitting base material, a first surface facing the base material, and a second surface opposite to the first surface, and the second surface is one-dimensional. Or a birefringent member including a concavo-convex structure region each provided with a plurality of convex portions and / or concave portions arranged two-dimensionally and periodically, the concavo-convex structure region having a fast axis and a slow axis. The relief structure region has a relief structure forming layer having a cross-sectional shape perpendicular to the fast axis and a cross-sectional shape perpendicular to the slow axis, and a metal reflecting layer provided on the second surface. And the concavo-convex structure region has an oscillation direction of an electric field vector parallel to the fast axis when light having a certain wavelength in the visible light region is incident from a direction perpendicular to the second surface. and the reflected light of the linearly polarized light component such, the reflected light of the linearly polarized light component parallel to the vibration direction is the slow axis of the electric field vector By providing a phase difference of one half wavelength between the functions as a half-wave plate of a reflection type, a reflectivity for linearly polarized light component parallel vibration direction with respect to the fast axis of the electric field vector The display body functions as a linear polarizer when the vibration direction of the electric field vector is different from the reflectance with respect to the linearly polarized light component parallel to the slow axis.

The second aspect of the present invention, the period of the slow axis direction of the plurality of protrusions and / or recesses is a display body according to the first side surface is 400nm or less.

The third aspect of the present invention, each of the plurality of protrusions and / or recesses, a cross-section perpendicular to the fast axis is a display body according to the first or the second side surface has a tapered shape.

According to a fourth aspect of the present invention, in any one of the first to third side surfaces, each of the plurality of convex portions and / or concave portions has a height or depth within a range of 40 to 300 nm. Such a display body.

According to a fifth aspect of the present invention, the second surface includes a plurality of the concavo-convex structure regions, and two or more of the plurality of the concavo-convex structure regions include a shape of the plurality of convex portions and / or concave portions, and the plurality of convex portions. And / or the display according to any one of the first to fourth side surfaces in which at least one of the period of the recesses, the height or depth of the plurality of protrusions and / or recesses, and the direction of the fast axis is different. Is the body.

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

  According to the present invention, a display technique capable of forming a polarization latent image without using liquid crystal is provided.

The perspective view which shows roughly an example of the transmissive | pervious structural birefringent member which a convex part or a recessed part arranges one-dimensionally, and the cross section of an uneven | corrugated structure area | region is a rectangular wave shape. The perspective view which shows roughly an example of the reflective structural birefringent member which a convex part or a recessed part arranges one-dimensionally, and the cross section of an uneven | corrugated structure area | region is a rectangular wave shape. The graph which shows the example of the phase difference which the structural birefringent member of FIG.1 and FIG.2 gives. The perspective view which shows roughly an example of the reflective structural birefringent member which a convex part or a recessed part arranges one-dimensionally, and the cross section of an uneven | corrugated structure area | region is a sine wave shape. The perspective view which shows roughly an example of the reflective structural birefringent member in which the convex part or the recessed part was arranged two-dimensionally. The graph which shows the example of the influence which the height of a convex part or the depth of a recessed part has on the intensity | strength reflectance regarding a TE wave and TM wave. The graph which shows an example of the influence which the angle which the transmission axis of a polarizer makes with respect to a fast axis exerts on an intensity | strength reflectance when arrange | positioning the polarizer and the display body of FIG. The graph which shows the example of the influence which the height of a convex part or the depth of a recessed part has on the phase difference which a transmissive | pervious structural birefringent member and a reflective structural birefringent member give. The top view which shows an example of a display body roughly. Sectional drawing along the XX line of the display body of FIG. The graph which shows the example of the influence which the height of a convex part or the depth of a recessed part has on the intensity | strength reflectance regarding the TE wave and TM wave of a reflection type structural birefringent member. The top view which shows the other example of a display body roughly. The top view which shows an example of a labeled article schematically. The figure which shows an example of the authenticity determination method roughly.

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

  As described above, the display body according to the first side surface is formed with a relief structure having a light transmissive base material, a first surface facing the base material, and a second surface opposite to the first surface. And a metal reflective layer provided on the second surface. The second surface includes one or more concavo-convex structure regions each having a plurality of convex portions and / or concave portions arranged one-dimensionally or two-dimensionally and periodically. A portion corresponding to each of the concavo-convex structure regions functions as a birefringent member having a fast axis and a slow axis. Each concavo-convex structure region has a different cross-sectional shape perpendicular to the fast axis and a cross-sectional shape perpendicular to the slow axis.

First, a display technique used in the display body according to the first aspect will be described.
The display technique used here is a polarization latent image technique that visualizes a latent image that cannot be confirmed with the naked eye under normal illumination conditions by using a polarizer.

  Specifically, in this technique, an uneven structure is provided on the reflective surface of the display body, that is, the interface between the relief structure forming layer and the reflective layer, to cause structural birefringence described later. Then, using this structural birefringence, for example, information such as characters, pictures and designs is recorded. The latent image recorded in this way can be perceived as a visible image having a brightness distribution by observing with a polarizer. This visible image may be read with the naked eye or may be machine read.

  In this technique, for example, when a display is observed using a linear polarizer, the brightness of the portion of the display corresponding to the latent image is the angle formed by the transmission axis of the polarizer with respect to the fast axis or the slow axis. It changes according to. The fast axis or slow axis in the display body can be set in an arbitrary direction by appropriately designing the concavo-convex structure region, which is a region causing structural birefringence.

  Therefore, for example, when the angle of the fast axis is set to 0 ° for a certain concavo-convex structure region and the angle of the fast axis is set to 45 ° for another concavo-convex structure region, when the display body is observed through a linear polarizer, Of the display body, a portion corresponding to one concavo-convex structure region may appear bright, and a portion corresponding to the other concavo-convex structure region may appear dark. Then, the brightness and darkness thereof are reversed by rotating the polarizer.

  Further, the angle of the fast axis is set to 0 ° for a certain concavo-convex structure region, the angle of the fast axis is set to 45 ° for the other concavo-convex structure region, and the fast axis of the concavo-convex structure region is set to the two previous ones. When the display body is observed through a linear polarizer, the display body displays a gradation image when the display body is inclined with respect to the fast axis.

  The function described above for the concavo-convex structure region is manifested by providing a plurality of convex portions and / or concave portions on the second surface of the relief structure forming layer. Therefore, this technique is easy to use in combination with a relief type diffraction grating or hologram.

Here, “structural birefringence” will be described.
When a ridge-shaped convex portion or a groove-shaped concave portion is disposed at the interface between two transparent materials having different refractive indexes for light of a certain wavelength with a period equal to or shorter than the previous wavelength, this structure is obtained by the length of the convex portion or the concave portion. It may have different effective refractive indexes in the width direction and the width direction. The structural birefringence is birefringence due to the birefringence thus manifested.

For example, as shown in FIG. 1, a first transparent material layer 21 and a second transparent material layer 22 are laminated, and a plurality of rectangular grooves are formed on the surface of the first transparent material layer 21 in contact with the second transparent material layer 22. Consider a case in which natural light 40 having a certain wavelength is irradiated to a transmission type optical element in which a ridge-shaped convex portion or a groove-shaped concave portion 30 is arranged at a predetermined period on the interface thereof. . In this case, this structure has the refractive index n _TE and the vibration direction of the electric field vector in the width direction of the groove with respect to linearly polarized light (hereinafter referred to as TE wave) in which the vibration direction of the electric field vector is parallel to the length direction of the groove. Refractive index n _TM shown for parallel linearly polarized light (hereinafter referred to as TM wave) is expressed by the following formulas (1) and (2) (BORN AND WOLF “PRINCIPLES OF OPTICS Fourth edition” P705 (PERGAMON PRESS). )).

In the above formulas (1) and (2), n ₁ and n ₂ are the refractive indexes of the transparent material layers 21 and 22 at a certain wavelength λ, respectively. t ₁ is the distance between adjacent rectangular grooves, t ₂ is the width of the rectangular grooves, and H is the height of the convex part or the depth of the concave part. The relationship shown in the above equations (1) and (2) is established when the dimensions t ₁ and t ₂ are sufficiently smaller than the wavelength λ.

From the above formulas (1) and (2), it can be seen that the refractive indexes n ₁ and n ₂ satisfy the relationship represented by the inequality n _TE > n _TM . That is, the structure shown in FIG. 1 has a groove length direction 41 and a width direction 42 as a fast axis and a slow axis, respectively, and behaves equivalently to an optically anisotropic material. Although FIG. 1 shows an example in which the recess is a simple rectangular groove, structural birefringence can be realized even when the recess has another shape. For example, a plurality of convex portions or concave portions each having an elliptic cylinder shape are arranged at the interface of two transparent materials having different refractive indexes for light of a certain wavelength so that the major axes of the ellipses are parallel to each other. Structural birefringence can also be realized when arranged with a period shorter than the previous wavelength.

By the way, in order to realize a large refractive index difference n _TE −n _TM in the structure including the rectangular groove, a material having a refractive index n ₂ of about 1.5 as one of two transparent materials, for example, transparent Resin, glass or quartz is used, and air having a refractive index n ₁ of 1.0 is often used as the other transparent material. However, even if the refractive index difference is so large, in order to use the above structure as a half-wave plate for visible light, for example, when the dimensions t ₁ and t ₂ are 150 nm, the height or depth The thickness should be about 2700 nm. That is, a concave or convex portion having a large aspect ratio must be formed. It is difficult to form a groove or a protrusion having a large aspect ratio.

  In the display body according to the first aspect, structural birefringence is realized as follows. That is, the metal reflective layer 20 is used instead of the transparent material layer 22 as in the structure 10 shown in FIG.

When the transmission type is changed to the reflection type, the phase difference δ [rad] between the TE wave and the TM wave can be increased. That is, a sufficiently large refractive index difference n _TE −n _TM is realized by a recess or projection having a relatively small aspect ratio, for example, a recess or projection having an aspect ratio in the range of 0.5 to 1.5. be able to.

  FIG. 3 is a graph showing an example of the phase difference provided by the transmissive structural birefringent member in FIG. 1 and the phase difference provided by the reflective structural birefringent member in FIG. In the figure, the horizontal axis represents the height H of the convex portion (or the depth of the concave portion), and the vertical axis represents the phase difference δ obtained by simulation.

In this simulation, an FDTD (Finite Difference Time Domain) method was used. Here, the wavelength λ is 532 nm, the period P of the rectangular groove is 300 nm, and the interval t1 and the width t2 are both 150 nm. For the transmissive structural birefringent member, the transparent material layer 21 is made of a transparent resin having a refractive index n ₂ of 1.5, and the transparent material layer 22 is made of air having a refractive index n ₁ of 1.0. As for the reflective structural birefringent member, the transparent material layer 21 is made of a transparent resin having a refractive index n ₂ of 1.5, and the metal reflective layer 20 is made of aluminum having a refractive index n ₃ of 0.887-6.26i. It was decided to consist of.

  As shown in FIG. 3, in the reflective structural birefringent member, the increase in the phase difference δ with respect to the height H is much larger than that in the transmissive structural birefringent member. Therefore, according to the reflective structural birefringent member, even when the aspect ratio of the convex portion or the concave portion is relatively small, for example, the phase delay δ = π necessary for the half-wave plate or 1 / The phase delay δ = π / 2 necessary for the four-wave plate can be realized.

  In the reflective structural clothing refracting member, any material may be used as the transparent material as long as it is transparent to light of wavelength λ. As the transparent material, for example, air, transparent resin, or quartz can be used. As the metal material, various materials such as aluminum (Al), gold (Au), silver (Ag), and nickel (Ni) can be used. The metal material is desirably a material having a high reflectance with respect to light having a wavelength λ.

  In the reflective structural birefringent member, the convex portion or the concave portion may have various shapes. For example, as shown in FIG. 4, the convex portion or the concave portion is a bowl-shaped convex portion or a groove-shaped concave portion arranged in the width direction and having a cross section perpendicular to the length direction having a tapered shape. May be. Here, the “tapered shape” means a shape in which the cross-sectional area parallel to the second surface of the convex portion or the concave portion decreases as the distance from the second surface increases.

  Alternatively, as shown in FIG. 5, the convex portion or concave portion 32 has a shape extending in one direction when viewed from the height or depth direction, and is two-dimensional so that the length direction is substantially parallel. They may be arranged in order.

  Even in these cases, substantially the same effect as described above for the structure of FIG. 2 can be obtained.

  Of course, if the refractive index of the transparent material, the type of the metal material, the shape of the convex portion or the concave portion, and the like are different, the height H of the convex portion or the depth of the concave portion necessary to realize a certain phase difference δ is also different. . However, in any case, according to the reflective structural birefringent member, the desired phase difference δ is achieved with a much smaller height H or depth than the transmissive structural birefringent member. be able to.

  As is apparent from the above, the display body according to the first side surface has a concavo-convex structure region in the laminate of the relief structure forming layer and the metal reflection layer without excessively increasing the aspect ratio of the convex part or the concave part. A function as a birefringent member having a fast axis 41 and a slow axis 42 can be imparted to the portion corresponding to. Therefore, the display body according to the first aspect can hold the polarization latent image visualized by observing through the polarizer relatively easily.

  Moreover, in this display body, the reflectance with respect to the TE wave can be made different from the reflectance with respect to the TE wave.

  FIG. 6 is a graph showing an example of the influence of the height H of the convex portion (or the depth of the concave portion) on the intensity reflectance related to the TE wave and the TM wave. In the figure, the horizontal axis represents the height H of the convex portion (or the depth of the concave portion), and the vertical axis represents the intensity reflectance obtained by the simulation. This simulation was performed under the same method and conditions as the simulation described with reference to FIG.

  As shown in FIG. 6, the reflectivity with respect to the TE wave gradually decreases as the height H increases. On the other hand, the reflectance with respect to the TM wave decreases with vibration as the height H increases. Therefore, by setting the height H of the convex portion (or the depth of the concave portion) so that the difference between the reflectivity for the TE wave and the reflectivity for the TM wave is sufficiently large, A function as a linear polarizer can be imparted.

  Therefore, for example, when the angle of the fast axis is set to 0 ° for a certain concavo-convex structure region and the angle of the fast axis is set to 90 ° for another concavo-convex structure region, when the display body is observed through a linear polarizer, Of the display body, a portion corresponding to one concavo-convex structure region may appear bright, and a portion corresponding to the other concavo-convex structure region may appear dark. Then, the brightness and darkness thereof are reversed by rotating the polarizer.

  Further, the angle of the fast axis for a certain concavo-convex structure region is set to 0 °, the angle of the fast axis is set to 90 ° for another concavo-convex structure region, and the fast axis of the concavo-convex structure region for the other one or more When the display body is observed through a linear polarizer, the display body displays a gradation image when the display body is inclined with respect to the fast axis.

  As described above, the display body according to the second aspect employs the following configuration in the display body according to the first aspect. That is, in the display body according to the second side surface, the birefringent member has an oscillation direction of the electric field vector as a fast axis when light having a certain wavelength in the visible light region is incident from a direction perpendicular to the second surface. A phase difference of a half wavelength is given between the linearly polarized light component parallel to the linearly polarized light component and the linearly polarized light component whose electric field vector oscillation direction is parallel to the slow axis.

  For example, when the display body and the linear polarizer are overlapped so that the transmission axis of the linear polarizer forms an angle of 45 ° with respect to the fast axis, and the display body is observed through the linear polarizer, the display body Of these, the portion corresponding to the concavo-convex structure region appears dark. For example, a portion of the display body corresponding to the concavo-convex structure region appears black.

  Thus, the part corresponding to the concavo-convex structure region in the display body can function as a half-wave plate. In addition, as described above, the portion of the display body corresponding to the concavo-convex structure region can function as a linear polarizer by setting the height H of the convex portion (or the depth of the concave portion). Therefore, display using both the function as a wave plate and the function as a polarizer is possible.

  For example, when the structure described with reference to FIGS. 2 and 3 is adopted, as shown in FIG. 3, when the height H of the convex portion (or the depth of the concave portion) is 40 nm, the phase difference δ is π. That is, the function of a half-wave plate can be imparted to the portion corresponding to the concavo-convex structure region. In this case, as shown in FIG. 6, the reflectance for the TE wave is 86% and the reflectance for the TM wave is 30%, that is, the function as a linear polarizer in the portion corresponding to the concavo-convex structure region. Can be granted. Therefore, in this case, the display bodies can exhibit optical characteristics corresponding to them.

  FIG. 7 is a graph showing an example of the influence of the angle formed by the transmission axis of the polarizer with respect to the fast axis on the intensity reflectance when the polarizer and the display body of FIG. In the figure, the horizontal axis represents the angle formed by the transmission axis of the polarizer with respect to the fast axis, and the vertical axis represents the intensity reflectance obtained by simulation. This simulation was performed under the same method and conditions as the simulation described with reference to FIG.

  If a function corresponding to a half-wave plate and a function as a linear polarizer are given to the portion corresponding to the uneven structure region, for example, as shown in FIG. 7, the transmission axis of the polarizer is parallel to the fast axis. In this case, the intensity reflectance becomes maximum, and when the transmission axis of the polarizer is perpendicular to the fast axis, the intensity reflectance becomes smaller, and the angle formed by the transmission axis of the polarizer with respect to the fast axis is 45. The intensity reflectance is minimized when the angle is in the range of 60 ° to 60 °. That is, if a function corresponding to a half-wave plate and a function as a linear polarizer are imparted to a portion corresponding to the concavo-convex structure region, complicated optical characteristics can be achieved.

  As described above, the display body according to the third aspect employs the following configuration in the display body according to the first or second aspect. That is, in the display body according to the third aspect, the period in the direction parallel to the slow axis of the convex part and / or the concave part is 400 nm or less.

  In this way, when visible light is incident on the display body at an incident angle of about 0 °, the display body does not emit diffracted light. That is, in this case, it is possible to prevent the presence of the concavo-convex structure region from being perceived without a polarizer due to the portion of the display body corresponding to the concavo-convex structure region emitting diffracted light.

  In addition, the period of the direction parallel to the slow axis of a convex part and / or a recessed part is 100 nm or more, for example. Protrusions and / or recesses arranged with a small period are difficult to form with high accuracy.

  As described above, the display body according to the fourth aspect adopts the following configuration in the display body according to any one of the first to third side surfaces. That is, in the display body according to the fourth side surface, each of the convex part and / or the concave part has a tapered shape in a cross section perpendicular to the fast axis, as shown in FIG.

  When this structure is employed, the relationship between the height H of the convex portion or the depth of the concave portion and the phase difference δ can be made close to linear. Therefore, when an error occurs in the height H of the convex portion or the depth of the concave portion, it is possible to prevent the phase difference δ from greatly deviating from the design value.

  FIG. 8 is a graph showing an example of the influence of the height of the convex portion or the depth of the concave portion on the phase difference given by the reflective structural birefringent member shown in FIG. In the figure, the horizontal axis represents the height H of the convex portion or the depth of the concave portion, and the vertical axis represents the phase difference δ obtained by simulation. This simulation is similar to the simulation described with reference to FIG. 3 except that the shape of the projections or depressions is changed so that the cross section perpendicular to the length direction forms a sinusoidal array. Performed under conditions.

  As is clear from the comparison between FIG. 3 and FIG. 8, when the structure shown in FIG. 4 is adopted, the height H of the convex portion or the depth and position of the concave portion are compared with the case where the structure shown in FIG. 2 is adopted. The relationship with the phase difference δ can be made close to linear.

  Further, when the cross section perpendicular to the fast axis of each of the convex portion or the concave portion has a tapered shape, the substantial aspect ratio can be lowered, and the desired phase difference δ can be reduced with a smaller aspect ratio, for example, 0. An aspect ratio in the range of 3 to 1 can be realized. Therefore, in this case, when the concavo-convex structure is formed by transferring from the stamper to the resin, high releasability can be realized. That is, excellent mass productivity can be achieved.

  As described above, the display body according to the fifth aspect employs the following configuration in the display body according to any one of the first to fourth side surfaces. That is, in the display body according to the fifth aspect, each of the convex portion and / or the concave portion has a height or depth within a range of 40 to 300 nm. This structure is advantageous in reducing the aspect ratio of the convex portion or the concave portion.

  As described above, the display according to the sixth aspect employs the following configuration in the display according to any one of the first to fifth aspects. That is, in the display body according to the sixth side surface, the second surface includes a plurality of uneven structure regions. Two or more of these concavo-convex structure regions have at least one of the shape of the convex portion and / or the concave portion, the period of the convex portion and / or the concave portion, the height or depth of the convex portion and / or the concave portion, and the direction of the fast axis. Is different.

  The shape of the convex part and / or the concave part, the period of the convex part and / or the concave part, and the height or depth of the convex part and / or the concave part are the phase difference δ between the TE wave and the TM wave and the reflectance with respect to the TE wave and It affects the reflectivity for TM waves. Therefore, if one or more of these are different between the concavo-convex structure regions, portions corresponding to the concavo-convex structure regions appear to have different brightness when observed through a polarizer. As described above, when the display body is observed through the polarizer, the brightness of the portion corresponding to the concavo-convex structure region changes according to the angle formed by the transmission axis of the polarizer with respect to the fast axis.

Also, when observing the display body through a polarizer, the brightness of the portion corresponding to the concavo-convex structure region changes according to the angle formed by the transmission axis of the polarizer with respect to the fast axis. Are different between the concavo-convex structure regions, portions corresponding to the concavo-convex structure regions appear to have different brightness when observed through a polarizer.
Therefore, when the above configuration is adopted, a complicated visual effect can be achieved.

  As described above, the labeled article according to the seventh aspect includes the display body according to any one of the first to sixth aspects and the article that supports the display. Since this labeled article is provided with the above-described display body, it can exhibit a high anti-counterfeiting effect.

  Examples of the present invention will be described below.

(Example 1)
FIG. 9 is a plan view schematically showing an example of the display body. 10 is a cross-sectional view of the display body of FIG. 9 taken along line XX.

  The display body 100 shown in FIGS. 9 and 10 includes a transparent substrate 110, a relief forming layer 111, a metal reflective layer 113, and a protective layer 23. The relief structure forming layer 111, the metal reflective layer 113, and the protective layer 23 are sequentially formed on the transparent substrate 110. Here, the metal reflective layer 113 was formed by evaporating aluminum. Note that an adhesive layer may be formed instead of the protective layer 23 so that the display body 100 can be attached to the article.

  Regions TP1 to TP3 are provided at the interface between the relief structure forming layer 111 and the metal reflective layer 113. The regions TP1 and TP2 are uneven structure regions, and the region TP3 is a flat region.

  The regions TP1 and TP2 have the same structure as described with reference to FIG. 4 except for the following points. That is, here, in each of the regions TP1 and TP2, the period P of the convex portion or the concave portion is set to 240 nm. In region TP1, the fast axis is parallel to the y direction, the height H of the convex portion or the depth of the concave portion is 110 nm, and the phase difference δ given to the TE wave and the TE wave having a wavelength λ of 532 nm is π. It was made to become. On the other hand, in the region TP2, when the fast axis is parallel to the x direction, the height H of the convex portion or the depth of the concave portion is 220 nm, the phase difference δ given to the TE wave and the TE wave having a wavelength λ of 532 nm is 2π was set. The x direction and the y direction are parallel to the interface between the relief structure forming layer 111 and the metal reflective layer 113 and are perpendicular to each other.

  FIG. 11 is a graph showing an example of the influence of the height of the convex portion or the depth of the concave portion on the intensity reflectance related to the TE wave and TM wave of the reflective structural birefringent member. In the figure, the horizontal axis represents the height H of the convex portion (or the depth of the concave portion), and the vertical axis represents the intensity reflectance obtained by the simulation. This simulation was performed in the same manner as the simulation described with reference to FIG. 3 except that the conditions described with reference to FIGS. 9 and 10 were applied.

  According to FIG. 11, in both cases where the height H of the convex portion or the depth of the concave portion is 110 nm and 220 nm, the reflectance for the TE wave is about 90%, and the reflectance for the TM wave is about 90%. 62%.

  Therefore, when the display body 100 described with reference to FIGS. 9 and 10 is observed with the naked eye, the regions TP1 and TP2 look almost the same brightness and cannot be distinguished from each other. That is, in this case, the display body 100 displays a rectangular image.

  In addition, when a linear polarizer is overlaid on the display body 100 so that the transmission axis thereof is parallel to the x or y direction, the regions TP1 and TP2 appear to have almost the same brightness. It cannot be distinguished from each other. That is, also in this case, the display body 100 displays a rectangular image.

  However, when the linear polarizer is superimposed on the display body 100 so that the transmission axis forms an angle of 45 ° with respect to the x or y direction, the phase difference given by the portions corresponding to the regions TP1 and TP2 Due to the difference in δ, the portion corresponding to the region TP1 appears darker than the portion corresponding to the region TP2. That is, in this case, the portion corresponding to the region TP1 displays the character “T”, and the portion corresponding to the region TP2 displays the background of the character “T”.

(Example 2)
FIG. 12 is a plan view schematically showing another example of the display body.

  The display body 100 shown in FIG. 12 is the same as the display body 100 described with reference to FIGS. 9 and 10 except that the following configuration is adopted.

  That is, in the display body shown in FIG. 12, regions AR1 to AR7 are provided at the interface between the relief structure forming layer 111 and the metal reflective layer 113 instead of the regions TP1 to TP3. The areas AR1 to AR6 are uneven structure areas, and the area AR7 is a flat area.

  The regions AR1, AR2, AR3, AR4, AR5, and AR6 have their fast axes at angles of 0 °, 30 °, 60 °, 90 °, 120 °, and 150 ° with respect to the x direction, respectively. Except this, it has the same structure. The phase difference δ that each of the regions AR1 to AR6 gives to the TE wave and the TE wave having a wavelength of 532 nm is π.

  When a linear polarizer is overlaid on the display body 100 so that the transmission axis forms an angle of 15 ° with respect to the x direction, the portions corresponding to the areas AR3 and AR6 appear black, and the areas AR1 and AR2 , Portions corresponding to AR4 and AR5 appear brighter. When a linear polarizer is superimposed on the display body 100 so that the transmission axis forms an angle of 45 ° with respect to the x direction, the portions corresponding to the areas AR1 and AR4 appear black, and the area AR2 , Portions corresponding to AR3, AR5 and AR6 appear brighter. When the linear polarizer is superimposed on the display body 100 so that the transmission axis forms an angle of 75 ° with respect to the x direction, the portions corresponding to the areas AR2 and AR5 appear black, and the area AR1. , AR3, AR4 and AR6 appear brighter.

  As apparent from the above, when the linear polarizer is rotated in a state where the linear polarizer is overlaid on the display body 100, the place where it looks black also changes accordingly. That is, an animation-like display is possible.

  In Examples 1 and 2, a polarizer is stacked on the display body 100, but the polarizer may be separated from the display body 100.

(Example 3)
FIG. 13 is a plan view schematically showing an example of a labeled article.
The labeled article shown in FIG. 13 is a printed matter. The printed matter includes a display body 100 as a label and an article 101 to which the display body 100 is attached. The display body 100 has the structure described with reference to Example 1 or Example 2. Here, the article 101 is an information printed matter that requires anti-counterfeiting technology such as an ID card.

  FIG. 14 is a diagram schematically illustrating an example of a true / false determination method. In FIG. 14, reference numerals 130 and VW1 represent a linear polarizer and an observer, respectively.

  The labeled article described with reference to FIG. 13 includes the display body 100 described with reference to Example 1 or Example 2. The display body 100 provides the visual effect described with reference to Example 1 or Example 2 when the viewer VW1 observes through the polarizer 130. Therefore, by confirming this visual effect, it can be determined that the labeled article is genuine.

  As described above, when the display body 100 of Example 1 or Example 2 is supported by the article 101, it is possible to impart an anti-counterfeit effect to the article 101 or to enhance the anti-counterfeit effect of the article 101.

  In addition, although the ID card is illustrated as the labeled article in FIG. 13, the labeled article is not limited to this. For example, the labeled article may be a magnetic card, a wireless card, an IC (integrated circuit) card, or another card such as a passport. Alternatively, the labeled article may be securities such as gift certificates and stock certificates. Alternatively, the labeled article may be a tag to be attached to an article to be verified as authentic. Alternatively, the labeled article may be a package or a part thereof that contains an article to be confirmed to be genuine.

  In the labeled article shown in FIG. 13, the display body 100 is attached to the article 101. However, the display body 100 can be supported by the article 101 by other methods. For example, when paper is used as the article 101, the display body 100 may be rolled into the paper and the paper may be opened at a position corresponding to the display body 100. Alternatively, when a light-transmitting material is used as the article 101, the display body 100 may be embedded therein, or the display body 100 may be fixed to the back surface of the article, that is, the surface opposite to the display surface.

  Moreover, the labeled article may not be a printed material. That is, the display body 100 may be supported on an article that does not include a printed layer. For example, the display body 100 may be supported by a luxury product such as a work of art.

  The above embodiment is given for the purpose of facilitating understanding of the present invention, and it goes without saying that various modifications can be made without departing from the gist of the present invention.

  DESCRIPTION OF SYMBOLS 10 ... Structural birefringent member, 20 ... Metal reflecting layer, 21 ... Transparent material layer, 22 ... Transparent material layer, 23 ... Protective layer, 30 ... Convex part or concave part, 31 ... Convex part or concave part, 32 ... Convex part or Concave part, 40 ... natural light, 41 ... fast axis, 42 ... slow axis, 100 ... display body, 101 ... article, 110 ... base material, 111 ... relief structure forming layer, 113 ... metal reflection layer, 130 ... polarizer, AR1 ... Uneven structure region, AR2 ... Uneven structure region, AR3 ... Uneven structure region, AR4 ... Uneven structure region, AR5 ... Uneven structure region, AR6 ... Uneven structure region, AR7 ... Flat region, TP1 ... Uneven structure region, TP2 ... Uneven structure Area, TP3 ... flat area, VW1 ... observer.

Claims (6)

A light transmissive substrate;
A first surface facing the substrate and a second surface opposite to the first surface, wherein the second surface includes a plurality of convex portions arranged one-dimensionally or two-dimensionally and periodically; Each of which includes a concavo-convex structure region provided with a recess, the concavo-convex structure region functioning as a birefringent member having a fast axis and a slow axis, and the concavo-convex structure region has a cross section perpendicular to the fast axis. A relief structure forming layer having a shape different from that of the cross section perpendicular to the slow axis,
A metal reflective layer provided on the second surface;
When the light having a certain wavelength in the visible light region is incident on the concavo-convex structure region from a direction perpendicular to the second surface, reflection of the linearly polarized light component in which the vibration direction of the electric field vector is parallel to the fast axis is reflected. and light, by the vibration direction of the electric field vector gives a phase difference of one half wavelength between the reflected light of the linearly polarized light component parallel to the slow axis, functions as a half-wave plate for reflection-type In addition, the reflectance for the linearly polarized light component whose vibration direction of the electric field vector is parallel to the fast axis is different from the reflectance for the linearly polarized light component whose vibration direction of the electric field vector is parallel to the slow axis. A display body that functions as a linear polarizer.   The display body according to claim 1, wherein a period of the plurality of convex portions and / or concave portions in a direction parallel to the slow axis is 400 nm or less.   The display body according to claim 1, wherein each of the plurality of convex portions and / or concave portions has a taper shape in a cross section perpendicular to the fast axis.   The display body according to any one of claims 1 to 3, wherein each of the plurality of convex portions and / or concave portions has a height or a depth in a range of 40 to 300 nm.   The second surface includes a plurality of the concavo-convex structure regions, and two or more of the concavo-convex structure regions include a shape of the plurality of convex portions and / or concave portions, a period of the plurality of convex portions and / or concave portions, The display body according to any one of claims 1 to 4, wherein at least one of a height or depth of a plurality of convex portions and / or concave portions and a direction of the fast axis is different.   A labeled article comprising the display according to any one of claims 1 to 5 and an article supporting the display.

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