阅读说明：本技术 光学构造体以及认证体 (Optical structure and authentication body ) 是由 笼谷彰人 屋铺一寻 于 2018-07-26 设计创作，主要内容包括：本公开的光学构造体为，在量子化相位差构造层的一个面具有量子化相位差构造的光学构造体，量子化相位差构造为，尺寸恒定的多个量子化凸部与尺寸恒定的多个量子化凹部排列，在多重衍射区域具有量子化凸部沿一个方向排列而成的肋状凸部与量子化凹部相对于上述肋状凸部并行地排列而成的槽状凹部相邻且交替地配置的量子化相位差构造，多重衍射区域对在1个方向上离散且规则地配置的多个再现点进行再现。(An optical structure according to the present disclosure is an optical structure having a quantized phase difference structure on one surface of a quantized phase difference structure layer, wherein the quantized phase difference structure has a quantized phase difference structure in which a plurality of quantized protrusions having a constant size and a plurality of quantized recesses having a constant size are arranged, a rib-shaped protrusion in which the quantized protrusions are arranged in one direction and a groove-shaped recess in which the quantized recesses are arranged in parallel to the rib-shaped protrusion are arranged adjacent to each other and alternately in a multiple diffraction region, and the multiple diffraction region reproduces a plurality of reproduction dots which are discretely and regularly arranged in 1 direction.)

1. An optical structure having a quantized retardation structure on one surface of a quantized retardation structure layer,

the quantized phase difference structure is formed by arranging a plurality of quantized convex parts with constant size and a plurality of quantized concave parts with constant size,

a multiple diffraction region having a quantized phase difference structure in which rib-shaped protrusions in which the quantized protrusions are arranged in one direction and groove-shaped recesses in which the quantized recesses are arranged in parallel to the rib-shaped protrusions are arranged adjacent to and alternately with each other,

the multiple diffraction region is a quantized phase difference structure for reproducing a plurality of reproduction points which are arranged discretely and regularly in 1 direction.

2. The optical construct of claim 1 wherein,

the surface roughness of the bottom surface of the quantization recess of the quantization phase difference structure is different from the surface roughness of the top surface of the quantization recess of the quantization phase difference structure.

3. The optical construct of claim 1 wherein,

the plurality of multiple diffraction regions are regularly arranged in the quantized phase difference structure.

4. The optical construct of claim 3 wherein,

the direction of the spatial frequency component is determined by the direction in which the inclined surface of the convex structure in the multiple diffraction region faces.

5. The optical construct of claim 4 wherein,

using the length D of the entire multiple diffraction region and the wavelength λ of light in the multiple diffraction region, the shortest distance R from the plurality of reproduction points reproduced from the spatial frequency component to a plane on which the reproduction points are arranged satisfies R > D²The relationship of/λ.

6. The optical construct of claim 5 wherein,

the vector of incident light perpendicular to the plane is

A normal vector to the inclined surface of the virtual 3D-shaped polygon formed on the plane is

the arrangement direction of the plurality of reproduction points

when θ 1 is θ 2, the plurality of reproduction points are arranged in the arrangement direction

7. The optical construct of claim 6 wherein,

the light intensity distribution of the plurality of reproduction points is determined such that the light intensity of the reproduction point existing in the direction of specular reflection of the incident light on the inclined surface of the polygon is the strongest among the plurality of reproduction points, and the light intensity is weaker as the reproduction point is shifted from the direction of specular reflection among the plurality of reproduction points.

8. The optical construct of claim 6 wherein,

the plurality of reproduction points are spatially arranged at unequal intervals.

9. The optical construct of claim 3 wherein,

the multiple diffraction regions are of the haplotype.

10. The optical construct of claim 3 wherein,

the depth of the quantized phase difference structure is different for each of the multiple diffraction regions.

11. The optical construct of claim 3 wherein,

a reflection layer is provided on the surface of the quantized phase difference structure.

12. An authentication body characterized in that a plurality of authentication units,

the optical structure of claim 1.

13. An optical structure produced by laminating a release layer, an embossed layer and a reflective layer in this order on a film,

the embossed layer has a quantized phase difference structure in which the distance from the top surface of the quantized convex portion to the bottom surface of the quantized concave portion is constant regardless of the position in the multiple diffraction region,

the quantized phase difference structure has a plurality of peak intensities of spatial frequencies which are arranged in the embossed layer so as to be separated from each other in 1 direction or a plurality of directions.

14. The optical construct of claim 13 wherein,

the surface roughness of at least one of the top surface of the quantized convex portion or the bottom surface of the quantized concave portion is not more than one tenth of the distance.

15. The optical construct of claim 13 wherein,

the direction of the unevenness of the quantized phase difference structure is perpendicular to the direction in which the rib-like recessed portions and the groove-like recessed portions formed by the top surfaces of the quantized convex portions and the bottom surfaces of the quantized recessed portions extend.

16. The optical construct of claim 13 wherein,

the optical structure further includes a protective layer for protecting the reflective layer.

17. The optical construct of claim 13 wherein,

the optical structure is dispersed in a resin and applied as a printable ink.

18. The optical construct of claim 13 wherein,

the reflective layer has magnetic properties.

19. The optical construct of claim 13 wherein,

the embossed layer and the reflective layer have structural colors whose reflection spectra have peaks at least at wavelengths of 800nm to 1000nm, and the optical structure further includes an optical layer that reflects visible light and transmits infrared light.

20. The optical construct of claim 16 wherein,

the optical structure further includes a salt adsorbent in at least one of the embossed layer and the protective layer.

21. The optical construct of claim 13 wherein,

the number of peaks of the spatial frequency of the quantized phase difference structure is set to 5 or more and 200 or less.

22. An optical structure having a quantized retardation structure on one surface of a quantized retardation structure layer,

the quantized phase difference structure is an element structure in which rib-shaped convex portions, which are quantized convex portions having a constant size as one element structure and are arranged in one direction, and groove-shaped concave portions, which are quantized concave portions having a constant size as the other element structure and are arranged in parallel with the rib-shaped convex portions, are alternately arranged adjacent to each other, and the depth from the upper surface of the rib-shaped convex portion to the bottom surface of the groove-shaped concave portion is constant, and the rib-shaped convex portions and the quantized concave portions are quantized,

the surface roughness of the bottom surface of the quantized phase difference structure is rougher than the surface roughness of the top surface,

the diffracted light of the quantized phase difference structure reproduces a plurality of reproduction points that are discrete in one direction.

Technical Field

Embodiments of the present invention relate to an optical structure applied as a forgery prevention means for improving security of securities, card media, passports, visas, and the like, and a certification body including the optical structure.

Background

Conventionally, three-dimensional representation provided by a hologram technique is applied as an anti-counterfeit means for improving security, particularly, as in a computer-synthesized hologram in which a wave surface of light is calculated by a computer.

The computer-generated hologram is a commercially excellent technique in that embossing can be performed for copying, and in this case, development processing is not required.

For example, patent document 1 (japanese patent application laid-open No. 2011-118034) discloses a method for stereoscopically displaying a virtual three-dimensional object by using anisotropic scattering of light.

Disclosure of Invention

However, according to the method disclosed in patent document 1, when light enters an inclined plane for pseudo-stereoscopic display, the brightness of the light is switched for each inclined plane, but the stereoscopic effect is poor.

Further, when the apparent light source size of the reference light to be irradiated to the hologram is large, a three-dimensional reproduced image is blurred.

In order to solve these disadvantages, it is necessary to limit observation conditions such as the size of the light source and the wavelength of the light source when observing the hologram. However, this imposes a burden on the observer.

In addition, in a calculator hologram formed from a general kinoform, when white light obtained by mixing a plurality of wavelengths is reproduced by a fine groove-shaped diffraction grating structure on the surface, color shift due to the angle of view occurs or diffraction is performed at an angle determined by the wavelength, so that iridescent diffracted light can be obtained. This is because when white incident light is incident, diffraction proceeds by the equidistant structure of the diffraction grating, and diffracted light of different wavelengths advances in different directions.

Security labels and the like that form images of holograms using iridescence are commercially available. For example, according to a conventional diffraction grating pattern, the color changes to rainbow color according to the positional relationship among the illumination, the display, and the observer.

However, in recent years, holograms that can be observed as iridescent colors can be easily produced, and sufficient forgery prevention capability cannot be achieved, and there is a market trend for demands for expression that replaces iridescent colors.

Therefore, a calculator hologram formed from a general kinoform cannot be applied to forgery prevention for securities such as gift certificates, card media such as credit cards, passports, visas, brand goods, machine parts, and the like, for example.

Furthermore, holograms are accompanied by characteristic blurring. In recent years, in order to improve such blurring, there is a technique of eliminating a dynamic visual effect, but in this case, there is a problem as follows: even if the angle of the field of view is changed, the image of the object is not changed at all, and the difference from the normal printed matter disappears.

Further, as described above, a calculator hologram formed from a general kinoform cannot be applied to forgery prevention for securities such as gift certificates, card media such as credit cards, passport, visa, brand goods, machine parts, and the like, and therefore, in order to determine authenticity of these, ink is generally used in addition to a hologram.

Such an ink is required to have high durability so that it can be used without fading even with the passage of time. Further, it is preferable that the color shift effect in a specific direction is not present so that the color does not change regardless of the direction from which the color is observed.

As a prior art relating to improvement of durability of ink, patent document 2 (specification of japanese patent No. 4916636) is disclosed. Patent document 2 discloses a pigment that provides two layers to a reflective layer and reduces the color shift effect by interference colors.

However, when the reflective layer is used by being colored and printed, the inclination angle of the pigment at the time of printing is random, and the color tone emitted in a certain direction depending on the direction in which the pigment is fixed is mixed. This makes it difficult to emit a color with high chroma.

In order to solve this problem, when printing is performed while controlling the orientation by a magnetic field, the color shift effect of the multilayer film as a film before pigmentation appears strongly, and the color gradually changes depending on the angle of emission of light, so that it is difficult to determine which color is a true color. In addition, in the case of a structural color obtained by using a general quantized phase difference structure, the color shift effect is also strong in many cases, and the same problem arises.

As summarized above, the hologram based on the diffraction grating has advantages such that an image with high brightness can be obtained and a high eye-catching effect is obtained, but has disadvantages such that the color largely changes depending on the angle of the label and a stable color development is not achieved.

Further, the following techniques are also known: the unique color development is realized by the interference between the flat upper surface of the convex portion and the plane other than the convex portion, and the stabilization of the color development is realized by scattering light at the convex portion. The color development by interference between the flat upper surface of the convex portion and the plane other than the convex portion has an advantage that a stable color development can be obtained with little color shift depending on the viewpoint and the position of the light source, but has a disadvantage that it is necessary to spread widely to stabilize the color development, and the luminance is lowered. The reduction in brightness causes a reduction in the effect of eye-robbery.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an optical structure which can realize a three-dimensional representation independent of a light source when displaying graphic information such as a pattern or character information, improve the appearance of iridescence, and obtain an appearance of glittering like a gemstone at once according to an angle of view, as an anti-counterfeit means for improving security of securities, card media, passports, visas, and the like, and an authentication body provided with the optical structure, and to provide a method for manufacturing the optical structure, which can solve the drawbacks of the conventional techniques such as diffraction and interference, that is, instability of color and reduction of brightness, using the technique of kinoform.

A second object of the present invention is to provide an optical structure which has high durability and does not have a color shift effect by applying a kinoform which can express high brightness, to an ink suitable for application to securities, card media, or printed matter such as passports and visas.

In order to achieve the above object, the following means is adopted in the embodiments of the present invention.

The optical structure for solving the first object is characterized in that the quantized phase difference structure is provided on one surface of the quantized phase difference structure layer, and the quantized phase difference structure is formed by arranging a plurality of quantized protrusions having a constant size and a plurality of quantized recesses having a constant size, the quantized phase difference structure is provided in which a rib-shaped protrusion having the quantized protrusions arranged in one direction and a groove-shaped recess having the quantized recesses arranged in parallel with the rib-shaped protrusion are adjacent to each other and alternately arranged in the multiple diffraction region, and the multiple diffraction region is a quantized phase difference structure for reproducing a plurality of reproduced dots which are arranged discretely and regularly in 1 direction.

In the optical structure, the surface roughness of the bottom surface of the quantization recess of the quantization phase difference structure is different from the surface roughness of the top surface of the quantization recess of the quantization phase difference structure.

In the optical structure, the plurality of multiple diffraction regions are regularly arranged in the quantized phase difference structure.

In the optical structure, the direction of the spatial frequency component is determined by the direction in which the inclined surface of the convex structure in the multiple diffraction region faces.

In the optical structure, the shortest distance R from a plurality of reproduction points reproduced from the spatial frequency component to the plane on which the reproduction points are arranged satisfies R > D using the length D of the entire multiple diffraction region and the wavelength λ of light in the multiple diffraction region²The relationship of/λ.

In the optical structure, the incident light vector perpendicular to the plane isA normal vector to the inclined surface of the virtual 3D-shaped polygon formed on the plane isAnd the above normal vector

The angle is theta 1, and the arrangement direction of the plurality of reproduction points is

And the above normal vector

The angle formed is θ 2, and when θ 1 is θ 2, the plurality of reproduction points are aligned in the arrangement directionThe distribution is performed.

In the optical structure, the light intensity distribution of the plurality of reproduction points is determined such that the light intensity is the strongest at a reproduction point existing in the direction in which the incident light is specularly reflected on the inclined surface of the polygon among the plurality of reproduction points, and the light intensity is weaker as the reproduction point is shifted from the direction of the specular reflection among the plurality of reproduction points.

In the optical structure, the plurality of reproduction points are spatially arranged at non-uniform intervals.

In the optical structure, the multiple diffraction region is a unit type.

In the optical structure, the depth of the quantized phase difference structure is different for each multiple diffraction region.

In the optical structure, a reflective layer is provided on the surface of the convex structure.

The authentication body further includes the optical structure.

Further, the optical structure may be configured to have a quantized phase difference structure on one surface of the quantized phase difference structure layer, the quantized phase difference structure is characterized in that rib-shaped convex portions, which are convex portions having a constant size as one element structure, and quantized convex portions, which are arranged in one direction, are adjacent to and alternately arranged with groove-shaped concave portions, which are concave portions having a constant size as the other element structure, which are quantized concave portions arranged in parallel with the rib-shaped convex portions, and the depth from the upper surface of the rib-shaped convex portions to the bottom surface of the groove-shaped concave portions is constant, and the rib-shaped convex portions and the groove-shaped concave portions are quantized into the element structure of the quantized convex portions and the quantized concave portions, the surface roughness of the bottom surface of the quantized phase difference structure is rougher than that of the upper surface, and diffracted light of the quantized phase difference structure reproduces a plurality of reproduction dots which are scattered in one.

An optical structure for solving the second object is an optical structure in which a release layer, an embossed layer, and a reflective layer are sequentially stacked on a film, wherein the embossed layer has a quantized phase difference structure, and a distance from a top surface of a quantized convex portion to a bottom surface of a quantized concave portion in the quantized phase difference structure is constant regardless of a position in a multiple diffraction region. The quantized phase difference structure has a plurality of peak intensities of spatial frequencies that are arranged in the embossed layer so as to be separated from each other in 1 direction or a plurality of directions.

In the optical structure, the surface roughness of at least one of the top surface of the quantized convex portion and the bottom surface of the quantized concave portion is one tenth or less of the distance. In the optical structure, the direction of the concavities and convexities of the quantized phase difference structure is perpendicular to the direction in which the rib-shaped concavities and groove-shaped concavities formed by the top surfaces of the quantized convex portions and the bottom surfaces of the quantized concavities extend.

In the optical structure, a protective layer for protecting the reflective layer is further laminated on the optical structure.

The optical structure is dispersed in a resin and applied as a printable ink. In the optical structure, the reflective layer has magnetic properties.

In the optical structure, the reflection spectrum of the structural color of the embossed layer and the reflective layer has a peak at least at a wavelength of 800nm or more and 1000nm or less, and the optical structure further includes an optical layer that reflects visible light and transmits infrared light.

In addition, the optical structure further includes a salt adsorbent in at least one of the embossed layer and the protective layer.

In the optical structure, the number of peaks of the spatial frequency of the quantized phase difference structure is set to 5 or more and 200 or less.

According to the present optical structure, it is possible to provide an optical structure and an authentication body provided with the optical structure, which, when graphic information such as a pattern or character information is displayed as a forgery prevention means for improving security of securities, card media, passports, visas, and the like, can perform three-dimensional expression independent of a light source unlike a conventional hologram, can improve the appearance of a unique rainbow color of the conventional hologram, and can obtain an effect of flickering like a jewel at a moment according to a viewing angle.

In particular, in the present description, since the case where light is incident from the opposite direction of 180 ° with respect to the normal direction of the carrier is assumed as a calculation premise, and the light is designed to spread around the specular reflection direction, even when the light is incident obliquely with respect to the normal direction of the carrier, the light is reflected in almost the same direction as the reflection direction of the light in the case where the light actually has an inclined surface, and therefore the same brightness of the light as in the case where a virtual three-dimensional object exists can be observed in this place, and it can be observed as if there exists a three-dimensional object.

According to the present optical structure, the reflection direction of light when the light is incident perpendicularly to the plane can be defined by the quantized phase difference structure, and the reflection direction of the light can be made plural by having plural spatial frequency components.

This effect achieves an effect equivalent to the case where: when light is irradiated on an object and reflected, the specular reflection component is strongly reflected, and the reflected light intensity decreases as the angle is shifted from the specular reflection direction. In addition, by dispersing the spatial frequency component, bright and dark bright points can be generated, and a flash effect like a gem can be generated.

According to the present optical structure, a quantized phase difference structure can be configured by a plurality of multiple diffraction regions.

According to the optical structure, the direction of the spatial frequency component can be determined by the direction in which the inclined surface having a plurality of spatial frequencies is oriented.

According to the present optical structure, the diffraction region of the light diffracted from the multiple diffraction region is set to the Fraunhofer region, whereby an effect can be obtained that the light can be reflected in the direction of the reproduction point without directly observing the reproduction point.

According to the present optical structure, the effect of reflected light of light can be substituted by calculating diffraction in a simulated manner.

According to the present optical structure, the light intensity in the specular reflection direction is increased and the light intensity deviated from the specular reflection is decreased, whereby an effect that the light is irradiated to the actual surface can be achieved.

According to the present optical structure, it is possible to reflect a reproduced image whitely in a direction in which reproduction points are dense, and conversely, to reproduce an iridescent reproduced image such as a conventional hologram in a portion in which reproduction points are sparse, and to control both white and iridescent colors.

According to the present optical structure, the multiple diffraction regions can be made to be of a unit type.

According to the optical structure, the reflected color of light at the time of reflection can be controlled by quantizing the depth of the phase difference structure, and thus full-color representation of a three-dimensional image can be realized.

The optical structure provided with the reflective layer can also improve the light reflectance.

According to the present authentication body, it is possible to realize three-dimensional representation independent of a light source, and it is possible to improve the appearance of rainbow color unique to a conventional hologram, and to realize an effect of flickering like a jewel at a glance depending on an angle of view.

Further, according to the present optical structure, since the length from the top surface portion of the quantized convex portion to the bottom surface portion of the quantized concave portion in the quantized phase difference structure is constant regardless of the position in the embossed layer plane, by controlling the length, it is possible to control so that light of a specific wavelength is easily reflected.

In addition, in the quantized phase difference structure, by disposing a plurality of peak intensities of spatial frequencies so as to be separated in 1 direction or a plurality of directions, an effect of reducing a color shift effect and making the color tone uniform regardless of the direction can be achieved.

Further, since the surface roughness of at least either the top surface of the quantized convex portion or the bottom surface of the quantized concave portion is less than or equal to one tenth of the length from the top surface of the quantized convex portion to the bottom surface of the quantized concave portion and is rough, the reflection direction of light can be somewhat randomized without changing color by providing the quantized phase difference structure to such an extent that it does not depend on the wavelength of light. When there is no surface roughness at all on either the top surface of the quantized convex portion or the bottom surface of the quantized concave portion, and the distance from the top surface of the quantized convex portion to the bottom surface of the quantized concave portion slightly varies from the design value due to a manufacturing error, the color as a structural color sensitively varies, but by providing the surface roughness on either the top surface of the quantized convex portion or the bottom surface of the quantized concave portion as in the present optical structure, even if the length from the top surface of the quantized convex portion to the bottom surface of the quantized concave portion varies slightly, the color as a structural color does not vary greatly, and thus the manufacturing error can be alleviated to some extent.

Further, according to the present optical structure, since the direction of the irregularities of the quantized phase difference structure having the surface roughness is perpendicular to the extending direction of the rib-shaped concave portion and the groove-shaped concave portion formed by the top surface of the quantized convex portion and the bottom surface of the quantized concave portion, the light related to the structural color can be scattered in the perpendicular direction. This makes it possible to scatter light in a direction in which the color of the structural color is not changed, and thus a structure that is strong against manufacturing errors can be obtained.

In addition, the optical structure can protect the surface of the reflective layer by including a protective layer for protecting the reflective layer. In addition, the material of the protective layer is made to have the same refractive index as the material of the embossed layer, whereby the front and back sides are made to have the same structural color.

Further, since the present optical structure is produced by a method in which the reflective layer has magnetic properties, the reflective layer is oriented by a magnetic field in a specific direction and then the resin is cured.

Further, since the reflection spectrum of the structural color of the embossed layer and the reflection layer has a peak at least at a wavelength of 800nm or more and 1000nm or less, a printed matter that appears black in visible light and does not differ from a printed matter printed with normal black but reacts in infrared light can be produced. Thus, by applying the optical structure to a material such as concrete, the contrast between a portion where a crack is broken and a portion where no crack is broken can be emphasized in the inspection with infrared light, and therefore, the optical structure can be applied to the deterioration determination of a material such as concrete.

Further, by incorporating a salt adsorbent in at least one of the embossed layer and the protective layer, deterioration of the reflective layer due to salt in the atmosphere can be prevented.

The present optical structure has a quantized retardation structure on one surface of the quantized retardation structure layer. The quantized phase difference structure is an element structure in which rib-shaped convex portions, which are quantized convex portions having a constant size as one element structure and are arranged in one direction, and groove-shaped concave portions, which are quantized concave portions having a constant size as the other element structure and are arranged in parallel with the rib-shaped convex portions, are alternately arranged adjacent to each other, and the depth from the upper surface of the rib-shaped convex portion to the bottom surface of the groove-shaped concave portion is constant, and the rib-shaped convex portion and the quantized concave portions are quantized. The surface roughness of the bottom of the quantized phase difference structure is rougher than the surface roughness of the top surface, and diffracted light of the quantized phase difference structure reproduces a plurality of reproduction points that are discrete in one direction.

Drawings

Fig. 1A is a plan view showing a multiple diffraction region provided in an optical structure according to an embodiment of the present invention.

Fig. 1B is a graph showing the peak intensity of spatial frequency components in the multiple diffraction region shown in fig. 1A.

Fig. 2 is a plan view showing an example of an optical structure having a plurality of multiple diffraction regions.

Fig. 3 is a cross-sectional view showing a quantized phase difference structure.

Fig. 4A is a front view of a sphere, which is an example of a virtual three-dimensional shape.

Fig. 4B is a plan view of an optical structure for representing a sphere in fig. 4A in a simulated manner.

Fig. 4C is a sectional view showing a positional relationship between the optical structure in fig. 4B and the spherical body in fig. 4A.

Fig. 5 is a cross-sectional view of a portion of a polygon representing a virtual 3D shape for a sphere.

Fig. 6A is a diagram showing an embodiment of spatial frequency distribution.

Fig. 6B is a diagram showing an embodiment of spatial frequency distribution.

Fig. 6C is a diagram showing an embodiment of spatial frequency distribution.

Fig. 6D is a diagram showing an embodiment of spatial frequency distribution.

Fig. 7 is a sectional view showing a state in which the optical structure is bonded to the medium.

Fig. 8 is a cross-sectional view showing another mode of bonding the optical structure to the medium.

Fig. 9A is a sectional view schematically showing an example of the structure of an optical structure that is a material of the optical structure according to another embodiment of the present invention.

Fig. 9B is a cross-sectional view schematically showing another configuration example of an optical structure that is a material of the optical structure according to another embodiment of the present invention.

Fig. 10 is a sectional view schematically showing an example of the structure of the embossed layer constituting the optical structure.

Fig. 11A is a plan view showing an embodiment of a multiple diffraction region formed by an embossed layer.

Fig. 11B is a diagram showing an example of spatial frequency components in the multiple diffraction region shown in fig. 11A.

Fig. 11C is a graph showing an example of peak intensity in the multiple diffraction region shown in fig. 11A.

Fig. 12A is a plan view showing an example of an embodiment of spatial frequency components different from those in fig. 11B.

Fig. 12B is a plan view showing another example of the embodiment of spatial frequency components different from those in fig. 11B.

Fig. 12C is a plan view showing another example of the embodiment of spatial frequency components different from those in fig. 11B.

Fig. 13 is a photomicrograph obtained by observing a part of the surface of the quantized phase difference structure of the embossed layer by a scanning electron microscope.

Fig. 14 is a diagram added with a description for explaining the micrograph shown in fig. 13.

Fig. 15 is a photograph of an image obtained by the optical structure according to the embodiment of the present invention.

Detailed Description

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

(optical Structure and authentication body)

Fig. 1A is a plan view showing an embodiment of the multiple diffraction region 12 in the quantized phase difference structure included in the optical structure 10 according to the embodiment of the present invention, and fig. 1B is a diagram showing an example of peak intensities of spatial frequency components F1 to F5 of 5 reproduction points in the multiple diffraction region 12. The optical structure 10 has an embossed surface on one surface or both surfaces of the embossed layer. A part or the whole of the embossed surface has a multiple diffraction region. A quantized phase difference structure is formed in the multiple diffraction region.

As shown in fig. 1A, the quantized phase difference structure is formed by arranging a plurality of quantized convex portions having a constant size and a plurality of quantized concave portions having a constant size. In fig. 1A, the brighter portion is a quantized convex portion, and the darker portion is a quantized concave portion. The quantization convex portions and the quantization concave portions are arranged at a constant interval. The quantization recesses or the quantization protrusions are arranged adjacent to the quantization protrusions at a constant interval. Furthermore, the quantization convex portions or the quantization concave portions are arranged adjacent to the quantization concave portions at a constant interval. For example, the quantized convex portions and the quantized concave portions of the quantized phase difference structure are alternately arranged one by one or a plurality of the quantized convex portions and the quantized concave portions are alternately arranged.

The quantized phase difference structure of the multiple diffraction region 12 is such that a spatial frequency component having a large period and a spatial frequency component having a small period are superimposed on the embossed surface by the arrangement of the quantized convex portions and the quantized concave portions. The multiple diffraction region 12 can be a cell including a quantized phase difference structure. The quantized phase difference structure of the multiple diffraction region 12 is such that rib-shaped protrusions, in which quantized protrusions are arranged in one direction, are adjacent to and alternately arranged with groove-shaped recesses, in which quantized recesses, which are recesses having a constant size as an element structure, are arranged in parallel with the rib-shaped protrusions. The size of the quantized convex portion may be equal to or less than half the center wavelength of the visible wavelength, and equal to or more than 1/20. The size of the quantization concave portion may be equal to or less than half the center wavelength of the visible wavelength, and equal to or more than 1/20. Specifically, the size of the quantized convex portion can be 250nm or less and 25nm or more. The size of the quantization concave portion can be 250nm or less and 25nm or more. The quantized convex portion can be square. The quantization recesses can be square. The corners of the quantized protrusions can be rounded. The corners of the quantized recesses can be rounded. The quantized convex portions and the quantized concave portions may be arranged in a virtual grid. The height of the quantized convex portion may be equal to or an integral multiple of the reference height. The depth of the quantization recess can be the same as or an integral multiple of the reference depth. The reference height and the reference depth can be set to be the same. The value of the integer multiple can be 1 to 4. In addition, the number of the grooves may be 1 to 8. The reference depth and the reference height may be 10nm to 500 nm.

When the reproduction of the hologram reproduced by the multiple diffraction region 12 is a reproduction point group of 5 points, if the spatial frequency components are calculated along 1 predetermined direction D in the plane of the multiple diffraction region 12 as shown in fig. 1A, spatial frequency components F1 to F5 corresponding to the reproduction point have discrete peaks of 5 points as shown in fig. 1B. In fig. 1B, the horizontal axis represents spatial frequency [1/mm ], and the vertical axis represents intensity of spatial frequency components.

When the discrete spatial frequency components are sparse, the reproduced image becomes rainbow color, and when the spatial frequency components are dense, the reproduced image becomes white. Further, by adjusting the density of the distribution of the spatial frequency components, it is possible to make the reproduced image rainbow in a certain angular direction and white in angles other than the certain angular direction.

Fig. 2 is a plan view showing an example of the optical structure 10a provided in the plurality of multiple diffraction regions 12.

In this way, the number of the multiple diffraction regions 12 included in the optical structure 10 is not limited to one as shown in fig. 1A, and may be plural as shown in fig. 2. The planar shape of each of the multiple diffraction regions 12 shown in fig. 1A and 2 is a rectangular shape, but may be a shape other than a rectangular shape.

Fig. 3 is a cross-sectional view showing the quantized phase difference structure 14.

The surface of the quantized phase difference structure 14 shown in a cross-sectional view in fig. 3 may be provided with a reflection layer not shown. The reflective layer can have light transmissive or light blocking properties.

The reflective layer can be a reflective layer formed of a metal material. The metal material can be Al, Ag, Sn, Cr, Ni, Cu, Au andalloys of these, and the like. The reflective layer made of metal can be a light-blocking reflective layer. Alternatively, the reflective layer may be a dielectric layer having a refractive index different from that of the relief structure formation layer. Alternatively, the reflective layer may be a multilayer dielectric film, which is a laminate of dielectric layers having different refractive indices between adjacent layers. In addition, the refractive index of a layer in contact with the relief structure formation layer among the dielectric layers included in the dielectric multilayer film is preferably different from the refractive index of the relief structure formation layer. The dielectric layer can be a metal compound or silicon oxide. The metal compound can be a metal oxide, a metal sulfide, a metal fluoride, or the like. The material of the dielectric layer can be TiO₂、ZnO、Si₂O₃、SiO、Fe₂O₃ZnS, CaF, MgF. The reflective layer can be formed by a vapor deposition method. As the vapor deposition method, a vacuum deposition method, a sputtering method, or the like can be applied. The reflective layer of the dielectric layer can have a light-transmitting property. The reflective layer can be 10nm to 1000 nm.

The reflective layer can be formed using ink. Depending on the printing mode, the ink can be offset, letterpress, intaglio, and the like. Further, depending on the composition, a resin ink, an oil ink, and an aqueous ink may be used. Further, depending on the drying method, oxidative polymerization type ink, permeation drying type ink, evaporation drying type ink, and ultraviolet curing type ink may be used.

In addition, as the reflective layer, functional ink whose color changes depending on the illumination angle or the observation angle may be used. As such functional Ink, optically Variable Ink (Optical Variable Ink), color-shifting Ink, and pearl Ink can be used.

In order to perform hologram calculation on a virtual polygon to be expressed using the quantized phase difference structure 14, the inclination angle of the polygon is determined, and the quantized phase difference structure 14 corresponding to the inclined surface 15 (see fig. 5 described later) of the inclination angle is calculated.

Fig. 4A is a front view showing a sphere 16 which is an embodiment of a simulated polygon represented by diffracted light of the quantized phase difference structure 14. Fig. 4B is a plan view showing the optical structure 10B in which the plurality of multiple diffraction regions 12 having the plurality of spatial frequency components in different directions are arranged in order to represent the sphere 16 as shown in fig. 4A in a simulated manner. Fig. 4C is a sectional view showing a positional relationship between the optical structure 10 and the spherical body 16.

Fig. 5 is a cross-sectional view of a part of a polygon representing a virtual 3D shape for the sphere 16. Formed by an inclined surface 15 having an inclination angle θ 1 with respect to a reference surface 18 of the multiple diffraction region 12.

Fig. 5 also shows the positional relationship between the inclined surface 15 and the reproduction point 20. As shown in fig. 5, in the embodiment of the present invention, by disposing the reproduction point 20 in the specular reflection direction of the inclined surface 15, it is possible to obtain a visual observation effect as if there is a virtual inclined surface 15 when light is incident.

When calculating the inclined surface 15 on which light is perpendicularly incident, the incident light vector perpendicular to the reference surface 18 is

The normal vector to the inclined surface 15 of the virtual 3D polygonal shape formed on the reference surface 18 is

Vector to normal

The angle is θ 1, and the arrangement direction of the plurality of playback points 20(#1) to (#5)

Vector to normal

The angle formed is θ 2, and when θ 1 is equal to θ 2, the angle is increasedThe playback points 20(#1) to (#5) are arranged in the array direction

The distribution is performed.

The shortest distance R from the playback points 20(#1) (#5) to the reference plane 18 satisfies R > D using the length D of the entire multi-diffraction region 12 and the wavelength λ of light in the multi-diffraction region 12²The relationship of/λ.

The light intensity distribution of the plurality of playback points 20(#1) to (#5) is determined such that the light intensity of the playback point 20(#3) existing in the direction in which the incident light is specularly reflected (regularly reflected) on the inclined surface 15 of the polygon is the strongest among the plurality of playback points 20(#1) to (#5), and the light intensity is weaker as the playback point is shifted from the direction of the specular reflection, that is, the light intensity is weaker in the order of playback point 20(#3) → playback point 20(#2) → playback point 20(#1), and playback point 20(#3) → playback point 20(#4) → playback point 20(# 5).

This enables calculation of the reflection intensity distribution of the inclined surface 15.

Further, a light intensity distribution different from the above-described light intensity distribution can also be applied. In addition, although fig. 5 shows an embodiment in which the plurality of playback points 20(#1) to (#5) are arranged at uniform intervals in space, the plurality of playback points 20(#1) to (#5) may be arranged at non-uniform intervals. These cases will be described with reference to fig. 6A to 6D. In fig. 6A to 6D, the horizontal axis represents the arrangement direction of the playback points 20, and the vertical axis represents the intensity of the playback points 20. In addition, on the horizontal axis

Corresponding to the direction of specular reflection.

Fig. 6A shows an embodiment in which reproduction points 20 are not arranged in the specular reflection direction, but 6 reproduction points 20 having equal intensity are arranged at equal intervals around the specular reflection direction. Fig. 6B shows an embodiment in which 11 reproduction points 20 having the same intensity are arranged so as to be relatively sparse in the vicinity of the specular reflection direction and relatively dense in a place distant from the specular reflection direction. Fig. 6C shows an embodiment in which the reproduction points 20 are not arranged in the specular reflection direction, but the reproduction points 20 are arranged at regular intervals so that the intensity becomes higher near the specular reflection direction and becomes lower as the intensity becomes farther from the specular reflection direction. Fig. 6D shows an embodiment in which the playback points 20 are not arranged near the specular reflection direction, but the playback points 20 are arranged such that the intensity gradually increases as they proceed further away from the specular reflection direction, and the intensity gradually decreases as they proceed further toward the specular reflection direction. In this embodiment, the intensity distribution of the playback points 20 can be set arbitrarily as described above.

As described above, in the embodiment of the present invention, as shown in fig. 5, by discretely disposing the reproduction points 20 with the specular reflection direction as the center, the image having the gloss which is complicatedly changed in each polygon depending on the viewpoint and the light source like a gem is reproduced. The intricately varying gloss can create a sparkling appearance.

Fig. 7 is a sectional view showing an embodiment in which the optical structure 10c is bonded to the cover 22 for application to the authentication material.

In order to bond the optical structure 10c to the cover 22, the quantized retardation structure 14 is provided on the carrier 24, the reflective layer 26 formed of a metal thin film is formed on the surface of the quantized retardation structure 14, the adhesive layer 28 is further provided on the surface, and the optical structure 10c is bonded to the cover 22 via the adhesive layer 28.

To suppress loss of reflected light, the carrier 24 is transparent. The material of the carrier 24 may be a rigid body such as glass or a thin film. The film can be a plastic film. The plastic film can be a PET (polyethylene terephthalate) film, PEN (polyethylene naphthalate) film, PP (polypropylene) film, or the like. Further, paper, synthetic paper, plastic multi-layer paper, resin impregnated paper, or the like may be used as the support depending on the application or purpose.

The material forming the quantized retardation structure 14 may be a thermoplastic resin such as a polyurethane resin, a polycarbonate resin, a polystyrene resin, or a polyvinyl chloride resin, a thermosetting resin such as an unsaturated polyester resin, a melamine resin, an epoxy resin, a polyurethane (meth) acrylate, a polyester (meth) acrylate, an epoxy (meth) acrylate, a polyol (meth) acrylate, a melamine (meth) acrylate, or a triazine (meth) acrylate, or a mixture thereof, and may further be a thermoformable material having a radical polymerizable unsaturated group, or the like.

Fig. 8 is a cross-sectional view showing another embodiment in which the optical structure 10d is bonded to the cover 22 for application to the authentication material.

The optical structure 10d shown in fig. 8 is different from the optical structure 10c shown in fig. 7 in that a peeling layer 30 is provided between the carrier 24 and the quantized phase difference structure 14 in order to peel the carrier 24.

After the optical structure 10d is bonded to the cover 22 by the adhesive layer 28, the carrier 24 is peeled off by peeling the release layer 30, and therefore the carrier 24 does not need to be transparent.

The material forming the release layer 30 can be resin. Further, the release layer 30 may also contain a lubricant. The resin may contain a thermoplastic resin, a thermosetting resin, an ultraviolet-curable resin, an electron beam-curable resin, or the like. The resin can be an acrylic resin, a polyester resin, a polyamide resin.

Further, the lubricant may be a wax such as polyethylene powder, paraffin, silicone, or carnauba wax. These can be applied as a release layer 30 on the carrier 24 layer. The coating can be performed by a known coating method. The coating can be gravure printing, micro gravure printing, or the like, die coating, lip coating, or the like. The thickness of the release layer 30 may be in the range of 0.5 μm to 5 μm.

According to the optical structure 10 according to the embodiment of the present invention, the graphic information such as a pattern or the character information is not iridescent, and has an appearance having a glossy feeling like a gem according to the viewpoint and the light source. The appearance looks like brightness flickering, one flashing and the other flashing according to different viewpoints and light sources. This appearance can improve the security for use in quantized phase difference structured securities, card media, passports, visas, and the like.