Color-developing structure

Abstract

To provide a color developing structure which can enhance designability of a color developing structure.SOLUTION: A surface 11F of a structural layer includes a plurality of narrow diffusion regions 11FN, and a plurality of wide diffusion regions 11FW. Each of the narrow diffusion regions 11FN and each of the wide diffusion regions 11FW extend along a first direction D1. In a second direction D2 orthogonal to the first direction D1, the narrow diffusion regions 11FN and the wide diffusion regions 11FW are alternately arranged. The plurality of narrow diffusion regions 11FN include narrow diffusion regions 11FN having a first length in the second direction D2, and narrow diffusion regions 11FN having a second length in the second direction D2, and the second length is different from the first length. The plurality of wide diffusion regions 11FW include wide diffusion regions 11FW having a third length in the second direction D2, and wide diffusion regions 11FW having a fourth length in the second direction D2, and the fourth length is different from the third length.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a color - generating structure.

Background Art

[0002] An example of a color - generating structure includes a concavo - convex structure layer and a multilayer film layer. The concavo - convex structure layer has a concavo - convex structure composed of a plurality of concavo - convex elements on its surface. The multilayer film layer is located on the concavo - convex structure and thus has a shape following the concavo - convex structure. The multilayer film layer is configured to emit reflected light enhanced by the interference of light in the multilayer film layer. Thereby, the color - generating structure exhibits a structural color due to the interference in the multilayer film layer (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, the above - mentioned color - generating structure is attached to various articles for the purpose of enhancing the design property of the article to which the color - generating structure is attached. The design property brought by the color - generating structure to the article contributes to enhancing the value and attractiveness of the article, etc., and thus a color - generating structure with higher design property is required.

Means for Solving the Problems

[0005] A color-generating structure for solving the above problems comprises a structural layer having a surface, and an optical layer located on the surface and having a shape that follows the surface, the optical layer reflecting light strengthened by interference. The surface includes a plurality of narrow diffusion regions and a plurality of broad diffusion regions. Each narrow diffusion region and each broad diffusion region extends along a first direction. In a second direction intersecting the first direction, the narrow diffusion regions and the broad diffusion regions are arranged alternately. The plurality of narrow diffusion regions include a narrow diffusion region having a first length in the second direction and a narrow diffusion region having a second length in the second direction, the second length being different from the first length. The plurality of broad diffusion regions include a broad diffusion region having a third length in the second direction and a broad diffusion region having a fourth length in the second direction, the fourth length being different from the third length.

[0006] According to the above-described color-emitting structure, narrow diffusion regions, where the range of diffused light is relatively narrow, and wide diffusion regions, where the range of diffused light is relatively wide, are arranged alternately. Therefore, the color-emitting structure can display patterns based on the contrast between the narrow diffusion regions and the wide diffusion regions. Furthermore, since each diffusion region includes diffusion regions of different lengths in the second direction, the monotony of the pattern, which would occur if only regions of the same length in the second direction were included, is reduced, and the complexity of the pattern is increased. This enhances the design appeal of the color-emitting structure.

[0007] In the above-described color-developing structure, in the second direction, the ratio of the minimum value in the narrow diffusion region to the maximum value in the broad diffusion region is 0.3 or more, and the ratio of the maximum value in the narrow diffusion region to the maximum value in the broad diffusion region is 1.0 or less, or the ratio of the minimum value in the broad diffusion region to the maximum value in the narrow diffusion region is 0.3 or more, and the ratio of the maximum value in the broad diffusion region to the maximum value in the narrow diffusion region is 1.0 or less.

[0008] According to the above color-generating structure, in the second direction, the difference between the length of the narrow diffusion region and the length of the wide diffusion region does not become too large, making it easier to display patterns based on the contrast between the narrow diffusion region and the wide diffusion region.

[0009] In the above-described color-developing structure, at least one of the plurality of narrow diffusion regions and the plurality of broad diffusion regions is a group of diffusion regions, and in the group of diffusion regions, the length in the second direction may vary aperiodically for each diffusion region.

[0010] According to the above color-generating structure, the length in the second direction changes aperiodically for each diffusion region within the diffusion region group, making it possible to display a pattern with aperiodicity throughout the entire diffusion region group.

[0011] In the above-described color-developing structure, each broad diffusion region comprises a plurality of uneven elements which are either a plurality of protrusions or a plurality of recesses, and each narrow diffusion region may comprise a plurality of uneven elements or a flat surface.

[0012] In the above-described color-developing structure, the uneven elements may have an elliptical shape or a polygonal shape inscribed in an ellipse when viewed from a viewpoint opposite to the surface.

[0013] In the above-described color-developing structure, the uneven elements have a long axis and a short axis, the length of the long axis is within the range of 10 μm to 200 μm, and the ratio of the length of the short axis to the length of the long axis may be within the range of 0.1 to 0.8.

[0014] According to the above-described color-emitting structure, the diffraction of light incident on multiple protrusions is suppressed by having the lengths of the major and minor axes each be 10 μm or more. By having the lengths of the major and minor axes each be 200 μm or less, the protrusions are suppressed from being visible to the observer of the color-emitting structure without using a magnifying tool. By having the ratio of the length of the minor axis to the length of the major axis be 0.8 or less, the protrusions can diffuse light anisotropically.

[0015] In the above-described color-developing structure, the dimensions of the uneven elements in the thickness direction of the structural layer may be within the range of 5 μm to 50 μm. With this color-developing structure, the formation of the protrusions is facilitated because the dimensions of the protrusions are within the range of 5 μm to 50 μm.

[0016] In the above-described color-developing structure, each narrow diffusion region comprises the plurality of uneven elements, and when viewed from a viewpoint opposite to the surface, the uneven elements of each broad diffusion region may be larger than the uneven elements of each narrow diffusion region.

[0017] According to the above-described color-generating structure, the size of the uneven elements in each diffusion region makes it possible to make the range in which light is scattered by the uneven elements in the broad diffusion region larger than the range in which light is scattered by the uneven elements in the narrow diffusion region.

[0018] In the above-described color-developing structure, the uneven elements have a long axis and a short axis, each narrow diffusion region comprises the plurality of uneven elements, each broad diffusion region comprises the uneven elements having the same shape as the uneven elements in each narrow diffusion region, and when viewed from a viewpoint facing the surface, the orientation of the long axis of the uneven elements in each broad diffusion region may intersect with the orientation of the long axis of the uneven elements in each narrow diffusion region.

[0019] According to the above-described color-generating structure, by adjusting the orientation of the major axis of the uneven elements in each diffusion region, it is possible to make the range in which light is scattered by the uneven elements in the broad diffusion region larger than the range in which light is scattered by the uneven elements in the narrow diffusion region.

[0020] In the above-described color-generating structure, the optical layer comprises a plurality of dielectric layers, and the refractive indices of adjacent dielectric layers in the thickness direction of the optical layer may differ from those of adjacent dielectric layers. With this color-generating structure, it is possible for the color-generating structure to exhibit a structural color corresponding to the refractive index of the dielectric layers constituting the optical layer.

[0021] In the above-described color-developing structure, an absorption layer may be further provided on the side opposite to the optical layer with respect to the structural layer, and the absorption layer absorbs at least a part of the light transmitted through the optical layer. According to this color-developing structure, light in a wavelength range different from the wavelength range of the dominant color of the reflected light in the optical layer is suppressed from being reflected at the interfaces of the respective layers inside the color-developing structure and at the interface between the color-developing structure and the outside of the color-developing structure. As a result, light in a wavelength range different from the wavelength range of the dominant color of the reflected light in the optical layer is suppressed from being emitted toward the observer. As a result, the vividness of the dominant color exhibited by the color-developing structure is enhanced.

Advantages of the Invention

[0022] According to the present invention, the design property of the color-developing structure can be enhanced.

Brief Description of the Drawings

[0023] [Figure 1] It is a cross-sectional view showing the structure of the color-developing structure in one embodiment. [Figure 2] It is a plan view schematically showing the structure of the surface viewed from the viewpoint facing the surface included in the color-developing structure shown in FIG. 1. [Figure 3] It is a three-view drawing showing a first example in the structure of the convex portion included in the color-developing structure shown in FIG. 1. [Figure 4] It is a three-view drawing showing a second example in the structure of the convex portion included in the color-developing structure shown in FIG. 1. [Figure 5] It is a plan view for explaining the direction of the long axis in the convex portion shown in FIG. 3. [Figure 6] It is a plan view showing an example in the structure of the color-developing structure shown in FIG. 2. [Figure 7] It is a plan view showing an example in the structure of the color-developing structure shown in FIG. 2. [Figure 8] It is a plan view showing an example in the structure of the color-developing structure shown in FIG. 2. [Figure 9] It is a schematic diagram for explaining the operation of the color-developing structure. [Figure 10] It is a schematic diagram for explaining the operation of the color-developing structure. [Figure 11] This is a schematic diagram illustrating the function of the color-developing structure. [Figure 12] This is a schematic diagram illustrating the function of the color-developing structure. [Figure 13] This is a diagram illustrating the function of the color-developing structure. [Figure 14] This is a diagram illustrating the function of the color-developing structure. [Figure 15] This is a diagram illustrating the function of the color-developing structure. [Figure 16] A graph showing the spectrum of reflected light in specular reflection. [Figure 17] A graph showing the relationship between the intensity and wavelength of light reflected from a narrow diffusion region, for each reception angle. [Figure 18] A graph showing the relationship between the intensity and wavelength of light reflected from a broad diffusion region, for each reception angle. [Figure 19] A graph showing the relationship between chromaticity x and the angle of reception. [Figure 20] A graph showing the relationship between chromaticity y and the angle of reception. [Figure 21] A graph showing the relationship between the intensity and wavelength of light reflected from a narrow diffusion region, for each reception angle. [Figure 22] A graph showing the relationship between the intensity and wavelength of light reflected from a broad diffusion region, for each reception angle. [Figure 23] This is a perspective view showing an example of applying an example of a color-generating structure to an example of an object to which it is attached. [Figure 24] Figure 23 is a schematic diagram illustrating the function of the color-developing structure shown. [Figure 25] Figure 23 is a cross-sectional view showing the structure of the color-developing structure. [Figure 26] This is a cross-sectional view showing the structure in the first modified example of the color-developing structure. [Figure 27] This is a perspective view showing the structure in the second modified example of the color-developing structure. [Figure 28] Figure 27 is a diagram illustrating the operation of the color-developing structure shown. [Modes for carrying out the invention]

[0024] An embodiment of the color-generating structure will be described with reference to Figures 1 to 25. In this disclosure, visible light refers to light contained in the wavelength range of 360 nm to 830 nm.

[0025] [structure] The structure of the color-developing structure will be explained with reference to Figures 1 to 8. As shown in Figure 1, the color-generating structure 10 comprises a structural layer 11 and an optical layer 12. The structural layer 11 has a surface 11F. The optical layer 12 is located on the surface 11F and has a shape that follows the surface 11F. The optical layer 12 reflects light that has been strengthened by interference. The optical layer 12 comprises a plurality of dielectric layers. In the thickness direction of the optical layer 12, the refractive indices of adjacent dielectric layers are different from each other. The color-generating structure 10 can exhibit a structural color corresponding to the refractive index of the dielectric layers constituting the optical layer 12.

[0026] The structural layer 11 is formed from a resin that is transparent to visible light, that is, a synthetic resin that transmits visible light. The synthetic resin forming the structural layer 11 may be, for example, an ultraviolet-curable resin or a thermoplastic resin.

[0027] In this embodiment, the optical layer 12 comprises a plurality of high refractive index layers 12a and a plurality of low refractive index layers 12b. In the optical layer 12, the high refractive index layers 12a and the low refractive index layers 12b are alternately stacked. The high refractive index layers 12a have a higher refractive index than the low refractive index layers 12b.

[0028] Each of the high refractive index layer 12a and the low refractive index layer 12b is a dielectric thin film. For example, in the optical layer 12, the layer in contact with the structural layer 11 is the high refractive index layer 12a, and the outermost layer of the optical layer 12 is the low refractive index layer 12b. The high refractive index layer 12a and the low refractive index layer 12b are formed from materials that are transparent to visible light, that is, materials that transmit visible light. As long as the refractive index of the high refractive index layer 12a is higher than the refractive index of the low refractive index layer 12b, the materials of the high refractive index layer 12a and the low refractive index layer 12b are not limited, but the greater the difference in refractive index between the high refractive index layer 12a and the low refractive index layer 12b, the more it is possible to obtain high-intensity reflected light with fewer layers.

[0029] Therefore, when the high refractive index layer 12a and the low refractive index layer 12b are formed from inorganic compounds, it is preferable that the high refractive index layer 12a is formed from titanium dioxide (TiO2) and the low refractive index layer 12b is formed from silicon dioxide (SiO2). However, each of the high refractive index layer 12a and the low refractive index layer 12b may be formed from an organic compound.

[0030] The film thickness of the high refractive index layer 12a and the low refractive index layer 12b can be designed using a transfer matrix method or the like, depending on the color to be produced by the color-producing structure. The film thickness of the high refractive index layer 12a and the low refractive index layer 12b can be selected, for example, from a range of 10 nm to 500 nm. The film thickness of each layer in the optical layer 12 may all be the same. Alternatively, the optical layer 12 may have a layer having a first thickness and a layer having a second thickness different from the first thickness.

[0031] In the example shown in Figure 1, the optical layer 12 comprises three high-refractive-index layers 12a and three low-refractive-index layers 12b. In the optical layer 12, the high-refractive-index layers 12a are in contact with the structural layer 11, and the high-refractive-index layers 12a and low-refractive-index layers 12b are stacked alternately. Alternatively, the low-refractive-index layers 12b may be in contact with the structural layer 11, and the low-refractive-index layers 12b and high-refractive-index layers 12a may be stacked alternately. Furthermore, as long as the high-refractive-index layers 12a and low-refractive-index layers 12b are stacked alternately, the number of high-refractive-index layers 12a and the number of low-refractive-index layers 12b may be different. The optical layer 12 may also include a dielectric layer having a first refractive index, a dielectric layer having a second refractive index, and a dielectric layer having a third refractive index.

[0032] When light is incident on the optical layer 12, the reflected light interferes at each interface between the high refractive index layer 12a and the low refractive index layer 12b. Furthermore, because the surface 11F of the structural layer 11 has irregularities, the angle of incidence of light to each interface changes within the color-emitting structure 10, causing the reflected light to be emitted in various directions. In other words, the reflected light from the optical layer 12 is scattered. As a result, light in a specific wavelength range, strengthened by interference, is emitted in various directions in response to incident light from various directions, and this allows light with a specific color to be visible over a wide observation angle. Note that even when the color-emitting structure 10 is observed from the opposite side of the optical layer 12 relative to the structural layer 11, or vice versa, the reflected light in the specific wavelength range described above can be observed.

[0033] Figure 2 schematically shows the structure of the color-developing structure 10 as viewed from a viewpoint opposite the surface 11F. As shown in Figure 2, the surface 11F includes multiple narrow diffusion regions 11FN and multiple broad diffusion regions 11FW. The area over which light diffused in the narrow diffusion regions 11FN spreads is narrower than the area over which light diffused in the broad diffusion regions 11FW spreads. Each narrow diffusion region 11FN and each broad diffusion region 11FW extends along the first direction D1. In the second direction D2, which is perpendicular to the first direction D1, the narrow diffusion regions 11FN and broad diffusion regions 11FW are arranged alternately.

[0034] A narrow diffusion region 11FN has a length LN along the second direction D2. A broad diffusion region 11FW has a length LW along the second direction D2. Multiple narrow diffusion regions 11FN include a narrow diffusion region 11FN having a first length in the second direction D2 and a narrow diffusion region 11FN having a second length in the second direction D2. The second length is different from the first length. Multiple broad diffusion regions 11FW include a narrow diffusion region 11FN having a third length in the second direction D2 and a broad diffusion region 11FW having a fourth length in the second direction D2. The fourth length is different from the third length.

[0035] Because the narrow diffusion regions 11FN, where the diffused light spreads over a relatively narrow range, and the wide diffusion regions 11FW, where the diffused light spreads over a relatively wide range, are arranged alternately, the color-emitting structure 10 can display patterns based on the contrast between the narrow diffusion regions 11FN and the wide diffusion regions 11FW. In other words, it is possible to display patterns based on the difference in brightness between the narrow diffusion regions 11FN and the wide diffusion regions 11FW. Furthermore, each diffusion region 11FN, 11FW contains diffusion regions 11FN, 11FW with different lengths in the second direction D2. This reduces the monotony that occurs when the pattern displayed by the color-emitting structure 10 contains only regions with the same length in the second direction D2, and increases the complexity of the pattern. As a result, the design quality of the color-emitting structure 10 is enhanced. This high design quality of the color-emitting structure 10 contributes to increasing the eye-catching appeal and value of the article to which the color-emitting structure 10 is attached.

[0036] In the second direction D2, the ratio of the minimum value in the narrow diffusion region 11FN at length LN to the maximum value in the broad diffusion region 11FW at length LW may be 0.3 or greater, and the ratio of the maximum value in the narrow diffusion region 11FN at length LN to the maximum value in the broad diffusion region 11FW at length LW may be 1.0 or less. Alternatively, the ratio of the minimum value in the broad diffusion region 11FW at length LW to the maximum value in the narrow diffusion region 11FN at length LN may be 0.3 or greater, and the ratio of the maximum value in the broad diffusion region 11FW at length LW to the maximum value in the narrow diffusion region 11FN at length LN may be 1.0 or less.

[0037] The minimum value of length LN in the narrow diffusion region 11FN is the minimum value LNmn, and the maximum value of length LN in the narrow diffusion region 11FN is the maximum value LMMX. The minimum value of length LW in the wide diffusion region 11FW is the minimum value LWmn, and the maximum value of length LW in the wide diffusion region 11FW is the maximum value LWMX. It is preferable that the length LN of the narrow diffusion region 11FN and the length LW of the wide diffusion region 11FW satisfy the following relationship.

[0038] LNmn / LWMX≧0.3 LNMX / LWMX ≤ 1.0 LWmn / LNMX≧0.3 LWMX / LNMX ≤ 1.0

[0039] As a result, in the second direction D2, the difference between the length LN of the narrow diffusion region 11FN and the length LW of the wide diffusion region 11FW does not become too large, making it easier to display patterns based on the contrast between the narrow diffusion region 11FN and the wide diffusion region 11FW.

[0040] At least one of the multiple narrow diffusion regions 11FN and the multiple broad diffusion regions 11FW constitutes a diffusion region group. In the diffusion region group, the length in the second direction D2 may vary aperiodically for each diffusion region 11FN and 11FW. That is, in the multiple narrow diffusion regions 11FN, the length LN in the second direction D2 may vary aperiodicly for each narrow diffusion region 11FN. Also, in the multiple broad diffusion regions 11FW, the length LW in the second direction D2 may vary aperiodicly for each broad diffusion region 11FW. In the example shown in Figure 2, each of the multiple narrow diffusion regions 11FN and the multiple broad diffusion regions 11FW constitutes a diffusion region group.

[0041] Thus, because the length in the second direction D2 changes aperiodically for each diffusion region 11FN and 11FW within the diffusion region group, it is possible to display a pattern with aperiodicity throughout the entire diffusion region group.

[0042] For each of the multiple narrow diffusion regions 11FN and multiple broad diffusion regions 11FW, the length in the second direction D2 for each diffusion region 11FN, 11FW can be set based on a pseudorandom number sequence. The pseudorandom number sequence can be obtained, for example, by a uniformly distributed integer random number, a uniform random number, a binary random number, a normally generated random number, a rejection sampling method, or a Markov chain Monte Carlo method. The normally generated random number can be, for example, an inverse function sampling method, a Box-Müller method, a ziggurat method, or a Marsaglia method. The Markov chain Monte Carlo method can be a Metropolis-Hastings method, a Hamiltonian Monte Carlo method, or a Langevin Monte Carlo method. The pseudorandom numbers may also be generated from a function based on a mathematical model. The mathematical model may be a dynamical model. The dynamical model may be an additive formula of a disturbance term, an elastic term, and a resistance term generated by pseudorandom numbers.

[0043] In the second direction D2, the boundary between adjacent narrow diffusion regions 11FN and broad diffusion regions 11FW may be linear, as shown in Figure 2. Alternatively, the boundary between the narrow diffusion region 11FN and the broad diffusion region 11FW may be curved. The curve is formed from a plurality of waves aligned along the first direction D1. The curve may be, for example, a sine wave. Alternatively, the boundary between the narrow diffusion region 11FN and the broad diffusion region 11FW may be polylinear. The polylinear has a plurality of inflection points aligned along the first direction D1, and the inflection points are connected by straight lines. The polylinear may be, for example, a rectangular wave or a triangular wave.

[0044] Figure 3 shows a first example of the uneven elements present in each broad diffusion region 11FW. Figure 4 shows a second example of the uneven elements present in each broad diffusion region 11FW. Each broad diffusion region 11FW is provided with multiple uneven elements, which are either multiple protrusions or multiple recesses. Figures 3 and 4 show examples of protrusions, which are examples of uneven elements. The uneven elements may also be recesses. Furthermore, each narrow diffusion region 11FN may be provided with multiple uneven elements, similar to the broad diffusion region 11FW, or it may be provided with a flat surface.

[0045] As shown in Figure 3, when viewed from a viewpoint opposite the surface 11F, the protrusion 11A can have an elliptical shape. The protrusion 11A has a major axis LA and a minor axis SA. The length of the major axis LA, LLA, may be, for example, within the range of 10 μm to 200 μm. The ratio of the length of the minor axis SA, LSA, to the length of the major axis LA, LLA (LSA / LLA), may be, for example, within the range of 0.1 to 0.8.

[0046] By having lengths of 10 μm or more for both the long axis LA and the short axis SA, diffraction of light incident on the multiple protrusions 11A is suppressed. By having lengths of 200 μm or less for both the long axis LA and the short axis SA, the protrusions 11A are suppressed from being visible to an observer of the color-emitting structure 10 without using a magnifying tool. By having a ratio of the length of the short axis SA (LSA) to the length of the long axis LA (0.8 or less), the protrusions 11A can diffuse light anisotropically.

[0047] In the thickness direction of the structural layer 11, the dimensions of the protrusions 11A may be, for example, within the range of 5 μm to 50 μm. Preferably, the dimensions of the protrusions 11A are within the range of 10 μm to 25 μm. By having the dimensions of the protrusions 11A within the range of 5 μm to 50 μm, the formation of the protrusions 11A is facilitated. In this embodiment, since the uneven elements are materialized as protrusions 11A, the dimensions of the protrusions 11A in the thickness direction of the structural layer 11 are the height H of the protrusions 11A. The height H of the protrusions 11A is the maximum value in the distance between the plane containing the valleys between the protrusions 11A and the protrusions 11A.

[0048] In a cross-section along the thickness direction, the outer diameter of the protrusion 11A has an arc shape. The protrusion 11A is a convex microlens. The contact angle θC of the protrusion 11A may be, for example, 5° or more and 40° or less. In this disclosure, the contact angle θC of the protrusion 11A is calculated using the tangential method in the cross-section of the protrusion 11A. The formation of the protrusion 11A by cutting is possible because the contact angle θC of the protrusion 11A is 40° or less.

[0049] As shown in Figure 4, when viewed from a viewpoint opposite the surface 11F, the protrusion 11A can have a polygonal shape inscribed in an ellipse. In the example shown in Figure 4, the protrusion 11A has a hexagonal shape. Note that the protrusion 11A may have a polygonal shape other than a hexagon.

[0050] The protrusion 11A has a long axis LA and a short axis SA. The length of the long axis LA, LLA, may be, for example, within the range of 10 μm to 200 μm. The ratio of the length of the short axis SA, LSA, to the length of the long axis LA, LLA (LSA / LLA), may be within the range of 0.1 to 0.8.

[0051] By having lengths of 10 μm or more for both the long axis LA and the short axis SA, diffraction of light incident on the multiple protrusions 11A is suppressed. By having lengths of 200 μm or less for both the long axis LA and the short axis SA, the protrusions 11A are suppressed from being visible to an observer of the color-emitting structure 10 without using a magnifying tool. By having a ratio of the length of the short axis SA (LSA) to the length of the long axis LA (0.8 or less), the protrusions 11A can diffuse light anisotropically.

[0052] In the thickness direction of the structural layer 11, the dimensions of the protrusions 11A may be within the range of 5 μm to 50 μm. Preferably, the dimensions of the protrusions 11A are within the range of 10 μm to 25 μm. By having the dimensions of the protrusions 11A within the range of 5 μm to 50 μm, the formation of the protrusions 11A is facilitated. In this embodiment, since the uneven elements are materialized as protrusions 11A, the dimensions of the protrusions 11A in the thickness direction of the structural layer 11 are the height H of the protrusions 11A. The height H of the protrusions 11A is the maximum value in the distance between the plane containing the valleys between the protrusions 11A and the protrusions 11A.

[0053] In a cross-section along the thickness direction, the outer diameter of the protrusion 11A has an arc shape. The protrusion 11A is a convex microlens. The contact angle θC of the protrusion 11A may be, for example, 5° or more and 40° or less. In this disclosure, the contact angle θC of the protrusion 11A is calculated using the tangential method in the cross-section of the protrusion 11A. The formation of the protrusion 11A by cutting is possible because the contact angle θC of the protrusion 11A is 40° or less.

[0054] Figure 5 shows the orientation of the protrusion 11A when viewed from a viewpoint opposite the surface 11F. Note that Figure 5 illustrates the first example of the uneven element. As shown in Figure 5, in the convex portion 11A shown by the dashed line, the major axis LA of the convex portion 11A extends along a direction parallel to the first direction D1. On the other hand, in the convex portion 11A shown by the solid line, the major axis LA of the convex portion 11A is inclined by an angle θT with respect to the first direction D1. For example, if the orientation of the convex portion 11A included in the wide diffusion region 11FW is different from the orientation of the convex portion 11A included in the narrow diffusion region 11FN, the angle θT of the major axis LA of the convex portion 11A in the narrow diffusion region 11FN with respect to the major axis LA of the convex portion 11A in the wide diffusion region 11FW may be within the range of 20° to 90°. Preferably, the angle θT is within the range of 45° to 90°. By having the angle θT within the range of 20° to 90°, it is possible to increase the contrast between the wide diffusion region 11FW and the narrow diffusion region 11FN.

[0055] Figures 6 to 8 each show examples of the structure of the broad diffusion region 11FW and the narrow diffusion region 11FN in a plan view opposite the surface 11F. In the example shown in Figure 6, each broad diffusion region 11FW has multiple protrusions 11AW. Each narrow diffusion region 11FN has multiple protrusions 11AN. Viewed from a viewpoint opposite the surface 11F, the protrusions 11AW of each broad diffusion region 11FW are larger than the protrusions 11AN of each narrow diffusion region 11FN. According to this example, the size of the protrusions 11AN and 11AW of each diffusion region 11FN and 11FW makes it possible to make the range over which light is scattered by the protrusions 11AW of the broad diffusion region 11FW larger than the range over which light is scattered by the protrusions 11AN of the narrow diffusion region 11FN. In the broad diffusion region 11FW, the long axis LA of the protrusion 11AW extends along a direction parallel to the first direction D1. In the narrow diffusion region 11FN, the long axis LA of the protrusion 11AN extends along a direction parallel to the first direction D1. In other words, the major axis LA of the convex portion 11AW and the major axis LA of the convex portion 11AN are parallel to each other.

[0056] In the example shown in Figure 7, each broad diffusion region 11FW has multiple protrusions 11AW. Each narrow diffusion region 11FN has multiple protrusions 11AN. The protrusions 11AW of each broad diffusion region 11FW have the same shape as the protrusions 11AN of each narrow diffusion region 11FN. Viewed from a viewpoint opposite the surface 11F, the orientation of the long axis LA of the protrusions 11AW of each broad diffusion region 11FW intersects with the orientation of the long axis LA of the protrusions 11AN of each narrow diffusion region 11FN. Depending on the orientation of the long axis LA of the protrusions 11AN and 11AW of each diffusion region 11FN, 11FW, it is possible to make the range in which light is scattered by the protrusions 11AW of the broad diffusion region 11FW larger than the range in which light is scattered by the protrusions 11AN of the narrow diffusion region 11FN. When viewed from a predetermined viewpoint opposite the surface 11F, the area in which light is scattered by the convex portion 11AW of the broad diffusion region 11FW is larger than the area in which light is scattered by the convex portion 11AN of the narrow diffusion region 11FN. In the example shown in Figure 7, the long axis LA of the convex portion 11AW and the long axis LA of the convex portion 11AN are orthogonal.

[0057] In the example shown in Figure 8, each broad diffusion region 11FW has multiple protrusions 11AW. In contrast, each narrow diffusion region 11FN does not have any uneven elements. In other words, the narrow diffusion region 11FN is a flat region relative to the broad diffusion region 11FW.

[0058] In the examples shown in Figures 6 to 8, the protrusions 11AN and 11AW have an elliptical shape, but as described above, the protrusions 11AN and 11AW may also have a polygonal shape. When the protrusions 11AN and 11AW have a polygonal shape, it is possible to increase the proportion that the protrusions 11AN and 11AW occupy on the surface 11F. Also, in the examples shown in Figures 6 to 8, the protrusions 11AN and 11AW are arranged in a grid pattern, but as long as the orientation of the protrusions 11AN and 11AW is fixed in a predetermined direction, the protrusions 11AN and 11AW within each diffusion region 11FN and 11FW may be arranged randomly. Furthermore, the density of the protrusions 11AN and 11AW between the narrow diffusion region 11FN and the wide diffusion region 11FW may be the same or different.

[0059] [Effect] The operation of the color-emitting structure 10 will be explained with reference to Figures 9 to 15. Specifically, with reference to Figures 9 to 12, examples of patterns that the color-emitting structure 10 can display will be explained in a plan view facing the surface 11F of the color-emitting structure 10. In the color-emitting structure 10 shown in Figures 9 to 12, the narrow diffusion region 11FN has a convex portion 11A. Next, with reference to Figures 13 to 15, the relationship between the orientation of the color-emitting structure 10 relative to the observer and the wavelength of light emitted from the color-emitting structure 10 will be explained.

[0060] Figure 9 shows an example in which the color-developing structure 10 comprises a narrow diffusion region 11FN having a linear shape extending along the first direction D1 and a wide diffusion region 11FW having a linear shape extending along the first direction D1. The long axes LA of the protrusions 11AN and 11AW located in each diffusion region 11FN and 11FW also extend along the first direction D1.

[0061] As shown in Figure 9, the narrow diffusion region 11FN and the wide diffusion region 11FW are arranged alternately along the second direction D2, so the color-generating structure 10 can display a pattern in which hairlines extending along the first direction D1 are connected along the second direction D2. Furthermore, since the outer shape of the region in which the narrow diffusion region 11FN and the wide diffusion region 11FW are arranged is star-shaped, the color-generating structure 10 can display a star shape formed by hairlines. Note that the area of ​​the surface 11F outside the region in which the narrow diffusion region 11FN and the wide diffusion region 11FW are arranged is a flat region 11FF. The flat region 11FF does not have any protrusions 11A.

[0062] Figure 10 shows an example in which the color-developing structure 10 comprises a narrow diffusion region 11FN having a wavy shape extending along the first direction D1 and a wide diffusion region 11FW having a wavy shape extending along the first direction D1. The long axes LA of the protrusions 11AN and 11AW located in each diffusion region 11FN and 11FW also extend along the first direction D1.

[0063] As shown in Figure 10, each of the narrow diffusion region 11FN and the wide diffusion region 11FW extends along the first direction D1 and has multiple inflection points aligned along the first direction D1. The narrow diffusion region 11FN and the wide diffusion region 11FW are arranged alternately along the second direction D2. Therefore, the color-generating structure 10 can display a pattern of multiple wavy lines aligned along the second direction D2 by contrast between the narrow diffusion region 11FN and the wide diffusion region 11FW. The area of ​​the surface 11F outside the region where the narrow diffusion region 11FN and the wide diffusion region 11FW are located is a flat region 11FF. The flat region 11FF does not have any protrusions 11A.

[0064] Figure 11 shows an example in which the color-developing structure 10 comprises a narrow diffusion region 11FN having a linear shape extending from the center of the surface 11F, and a wide diffusion region 11FW having a linear shape extending from the center of the surface 11F. The long axis LA of the protrusions 11AN and 11AW located in each diffusion region 11FN and 11FW extends along the direction in which the diffusion regions 11FN and 11FW in which the protrusions 11AN and 11AW are located extend.

[0065] As shown in Figure 11, each of the narrow diffusion region 11FN and the wide diffusion region 11FW has a straight line extending from the center of the surface 11F. The narrow diffusion region 11FN and the wide diffusion region 11FW are arranged alternately, for example, along a straight line SL that intersects each diffusion region 11FN and 11FW. If the narrow diffusion region 11FN and the wide diffusion region 11FW are arranged alternately, a flat region 11FF may be located between the narrow diffusion region 11FN and the wide diffusion region 11FW. The color-generating structure 10 can display a pattern containing multiple straight lines extending radially from the center of the surface 11F by contrast between the narrow diffusion region 11FN and the wide diffusion region 11FW.

[0066] Figure 12 shows an example in which the color-developing structure 10 comprises a narrow diffusion region 11FN having an annular shape and a wide diffusion region 11FW having an annular shape. As shown in Figure 12, the narrow diffusion region 11FN and the broad diffusion region 11FW each have annular shapes. The narrow diffusion region 11FN and the broad diffusion region 11FW located in the first region of the surface 11F have a concentric shape. Therefore, in the radial direction of the narrow diffusion region 11FN and the broad diffusion region 11FW, the narrow diffusion region 11FN and the broad diffusion region 11FW are arranged alternately. The protrusions 11AN and 11AW located in each diffusion region 11FN and 11FW are arranged such that their major axes LA are aligned along the circumferential direction of the diffusion region 11FN and 11FW in which they are located.

[0067] In the surface 11F, a second region distinct from the first region also contains narrow diffusion regions 11FN and broad diffusion regions 11FW. In the second region, the narrow diffusion regions 11FN and broad diffusion regions 11FW are concentric. In the radial direction of the narrow diffusion regions 11FN and broad diffusion regions 11FW, they are arranged alternately.

[0068] Therefore, in each of the first and second regions, the color-generating structure 10 can display a pattern of multiple interconnected rings in the radial direction of the narrow diffusion region 11FN and the wide diffusion region 11FW, due to the contrast between the narrow diffusion region 11FN and the wide diffusion region 11FW.

[0069] Figure 13 shows a state in which the optical layer 12 of the color-emitting structure 10 and the observer of the color-emitting structure 10 are facing each other, and the observer is observing the light reflected by the color-emitting structure 10. As shown in Figure 13, incident light IL, which is light incident on the color-generating structure 10, enters the color-generating structure 10 from the optical layer 12. The incident light IL is then reflected within the color-generating structure 10, and as a result, a portion of the incident light IL is emitted from the color-generating structure 10 as reflected light RL. As described above, the optical layer 12 emits light in a specific wavelength range that is strengthened by interference as reflected light RL. As a result, the observer OB can see the reflected light RL, which is light in a specific wavelength range.

[0070] Figure 14 shows a state in which the structural layer 11 of the color-emitting structure 10 and the observer OB are facing each other, and the observer OB is observing the light reflected by the color-emitting structure 10. As shown in Figure 14, the incident light IL enters the color-generating structure 10 from the structural layer 11. Even when the incident light IL enters from the structural layer 11, light in a specific wavelength range is amplified by interference in the optical layer 12, just as when the incident light IL enters from the optical layer 12. Therefore, light in the same wavelength range as when the optical layer 12 and the observer OB are facing each other is emitted from the color-generating structure 10 as reflected light RL. As a result, the observer OB can see the reflected light RL, which is light in a specific wavelength range.

[0071] Figure 15 shows a state in which the optical layer 12 of the color-producing structure 10 and the observer OB are facing each other, and the observer OB is observing the light transmitted through the color-producing structure 10. As shown in Figure 15, of the incident light IL incident from the structural layer 11, light in a specific wavelength range is reflected in an enhanced state due to interference in the optical layer 12. Therefore, the transmitted light TL that passes through the color-producing structure 10 does not contain light in a specific wavelength range that is enhanced in the optical layer 12. As a result, observer OB can see the transmitted light TL, which is light outside the specific wavelength range. In other words, the color of the color-producing structure 10 that observer OB sees when observing the reflected light RL is different from the color of the color-producing structure 10 that observer OB sees when observing the transmitted light TL.

[0072] [Wavelength of reflected light] Referring to Figures 16 to 22, the wavelengths of light reflected from the narrow diffusion region 11FN and the wavelengths of light reflected from the broad diffusion region 11FW will be explained.

[0073] Figures 16 to 20 show the results obtained from simulations for a color-producing structure 10 having a narrow diffusion region 11FN and a wide diffusion region 11FW, both of which have elliptical protrusions. In the simulations, the length of the minor axis of the protrusion 11AN in the narrow diffusion region 11FN was set to 0.12 mm, the length of the major axis to 0.19 mm, and the height to 0.011 mm. That is, the aspect ratio of the protrusion 11AN, which is the height divided by the length of the minor axis, was set to 0.058. Similarly, the length of the minor axis of the protrusion 11AW in the wide diffusion region 11FW was set to 0.19 mm, the length of the major axis to 0.27 mm, and the height to 0.024 mm. That is, the aspect ratio of the protrusion 11AW was set to 0.089.

[0074] Each diffusion region 11FN, 11FW was set in a square shape, and the width of each diffusion region 11FN, 11FW was set to 150 mm, and the length was set to 150 mm. The protrusions 11AN, 11AW were densely arranged along the long and short sides of each diffusion region 11FN, 11FW. Furthermore, a CIE standard D65 light source was set as the surface light source, and the incident angle to the color-generating structure 10 was set to 30°.

[0075] Figure 16 shows the spectrum when the light receiving angle is set to 30°. In Figure 16, the spectrum of light reflected from the narrow diffusion region 11FN is shown by a dashed line, the spectrum of light reflected from the wide diffusion region 11FW is shown by a dashed line, and the spectrum of light reflected from a structure without convex parts is shown by a solid line. In other words, the spectrum shown by the solid line represents the spectrum of light enhanced by interference in the optical layer.

[0076] As shown in Figure 16, the spectra obtained in the narrow diffusion region 11FN, the broad diffusion region 11FW, and the structure without protrusions all have a first peak at approximately 450 nm and a second peak at approximately 420 nm. When the color corresponding to the wavelength at the first peak is set as the first color and the color corresponding to the wavelength at the second peak is set as the second color, the ratio of the intensity of the second color (RI2 / RI1) to the intensity of the first color (RI1) is largest in the broad diffusion region 11FW and smallest in the structure without protrusions. Furthermore, the ratio of the intensity of the second color to the intensity of the first color is larger in the broad diffusion region 11FW than in the narrow diffusion region 11FN.

[0077] Figure 17 shows the spectra obtained when the light reception angle is changed from 20° to 50° for light reflected from the narrow diffusion region 11FN. As shown in Figure 17, regardless of the size of the reception angle, the spectrum of light reflected from the narrow-diffusion region 11FN has a first peak and a second peak. The intensity of the first peak when the reception angle is 20° is approximately equal to the intensity of the first peak when the reception angle is 30°, and the intensity of the second peak when the reception angle is 20° is approximately equal to the intensity of the second peak when the reception angle is 30°.

[0078] In the range where the light reception angle is 30° or greater, the intensity of the first peak is lower as the light reception angle increases, and the intensity of the second peak is also lower as the light reception angle increases. In the range where the light reception angle is 30° or greater, the ratio of the intensity of the second peak to the intensity of the first peak is higher as the light reception angle increases.

[0079] Figure 18 shows the spectra obtained when the receiving angle is changed from 20° to 50° for light reflected from the broad-diffusion region 11FW. As shown in Figure 18, regardless of the size of the reception angle, the spectrum of light reflected from the broad-diffusion region 11FW has a first peak and a second peak. The intensity of the first peak when the reception angle is 20° is approximately equal to the intensity of the first peak when the reception angle is 30°, and the intensity of the second peak when the reception angle is 20° is approximately equal to the intensity of the second peak when the reception angle is 30°.

[0080] In the range where the light reception angle is 30° or greater, the intensity of the first peak is lower as the light reception angle increases, and the intensity of the second peak is also lower as the light reception angle increases. In the range where the light reception angle is 30° or greater, the ratio of the intensity of the second peak to the intensity of the first peak is higher as the light reception angle increases.

[0081] In the broad diffusion region 11FW, the change in the intensity of the first peak and the change in the intensity of the second peak due to the change in the light reception angle are smaller than the respective changes in the narrow diffusion region 11FN.

[0082] Figure 19 shows the relationship between chromaticity x and the receiving angle in the xy chromaticity diagram. In Figure 19, the spectrum of light reflected from the narrow diffusion region 11FN is shown by a dashed line, the spectrum of light reflected from the wide diffusion region 11FW is shown by a dashed line, and the spectrum of light reflected from a structure without convex parts is shown by a solid line.

[0083] As shown in Figure 19, in the range of light reception angles from 20° to less than 35°, the chromaticity x values ​​are approximately equal in the narrow diffusion region 11FN, the wide diffusion region 11FW, and the structure without protrusions, and the chromaticity x increases with increasing light reception angle. In contrast, in the range of light reception angles from 35° to 50°, the chromaticity x values ​​in the narrow diffusion region 11FN and the wide diffusion region 11FW are smaller than the chromaticity x in the structure without protrusions. Furthermore, in the range of light reception angles of 35° or more, the difference between the chromaticity x in the structure without protrusions and the chromaticity x in each diffusion region increases as the light reception angle increases. Thus, by providing the color-generating structure 10 with a narrow diffusion region 11FN and a wide diffusion region 11FW, changes in chromaticity x caused by changes in the light reception angle are suppressed.

[0084] Figure 20 shows the relationship between chromaticity y and the receiving angle in the xy chromaticity diagram. In Figure 20, the spectrum of light reflected from a narrow diffusion region is shown by a dashed line, the spectrum of light reflected from a broad diffusion region is shown by a dashed line, and the spectrum of light reflected from a structure without convex parts is shown by a solid line.

[0085] As shown in Figure 20, in the range of light reception angles from 20° to less than 30°, the chromaticity y value in the structure without protrusions is greater than the chromaticity y value in each diffusion region 11FN and 11FW. On the other hand, in the range of light reception angles from 30° to 50°, the chromaticity y value in the structure without protrusions is smaller than the chromaticity y value in each diffusion region 11FN and 11FW. Thus, by providing the color-generating structure 10 with a narrow diffusion region 11FN and a wide diffusion region 11FW, changes in chromaticity y caused by changes in the light reception angle are suppressed.

[0086] Figures 21 and 22 show spectra obtained by actual measurements of light reflected from a color-producing structure 10 having a narrow diffusion region 11FN and a wide diffusion region 11FW, each having a square-shaped protrusion. The diagonal length of the protrusion 11AN in the narrow diffusion region 11FN was set to 44.8 μm, and its height to 7.9 μm. That is, the aspect ratio of the protrusion 11AN, obtained by dividing the height by the diagonal length, was set to 0.18. Similarly, the diagonal length of the protrusion 11AW in the wide diffusion region 11FW was set to 88.0 μm, and its height to 16.9 μm. That is, the aspect ratio of the protrusion 11AW was set to 0.19.

[0087] Figure 21 shows the spectrum of light reflected from the narrow diffusion region 11FN when the incident angle is 30°. Figure 21 also shows the spectrum of reflected light in the range of reception angles from -10° to 60°.

[0088] As shown in Figure 21, in the range of reception angles from -10° to 30°, the reflected light spectrum has a peak top extending from approximately 450 nm to 520 nm. In contrast, in the range of reception angles from 40° to 60°, the reflected light spectrum has a peak top extending from approximately 420 nm to 500 nm. In other words, the reflected light spectrum tends to shift the wavelength of the peak top to shorter wavelengths as the reception angle increases. Also, except for the case where the reception angle is -10°, the reflected light spectrum tends to have higher peak intensity as the reception angle decreases.

[0089] Figure 22 shows the spectrum of light reflected from the broad-diffusion region 11FW when the incident angle is 30°. Figure 22 also shows the spectrum of reflected light in the range of reception angles from -10° to 60°.

[0090] As shown in Figure 22, in the range of reception angles from -10° to 30°, the reflected light spectrum has a peak top extending from approximately 450° to 520°. In contrast, in the range of reception angles from 40° to 60°, the reflected light spectrum has a peak top extending from approximately 420 nm to 500 nm. That is, the reflected light spectrum tends to shift the wavelength of the peak top to shorter wavelengths as the reception angle increases. Also, in the range of reception angles from -10 to 30°, the reflected light spectrum tends to have higher peak intensity as the reception angle increases. Furthermore, in the broad diffusion region 11FW, the amount of change in peak intensity due to the change in reception angle is smaller than the amount of change in the narrow diffusion region 11FN.

[0091] [How to use the color-developing structure] An example of how to use the color-developing structure 10 will be explained with reference to Figures 23 to 25. Figure 23 shows a tennis racket to which the color-developing structure 10 is attached. The tennis racket is an example of an object to which the color-developing structure 10 is attached.

[0092] As shown in Figure 23, the tennis racket 100 comprises a head 100A having a substantially elliptical shape, a grip 100B having a prismatic shape, and a shaft 100C connecting the head 100A to the grip 100B. The shaft 100C has a surface 100CF and a side surface 100CS adjacent to the surface 100CF. The surface 100CF is a surface parallel to the plane on which the head 100A extends. The side surface 100CS is approximately perpendicular to the surface 100CF.

[0093] Figure 24 shows a magnified view of the portion of the side surface 100CS to which the color-developing structure 10 is attached. As shown in Figure 24, the color-emitting structure 10 is attached to a part of the side surface 100CS. When viewed from a viewpoint opposite the side surface 100CS, the color-emitting structure 10 has a rectangular shape that is aligned with the direction in which the side surface 100CS extends. In the color-emitting structure 10, the narrow diffusion region 11FN and the wide diffusion region 11FW described above have a shape that extends along the longitudinal direction of the color-emitting structure 10. Therefore, the color-emitting structure 10 displays an image with alternating alternating brightness and darkness along the longitudinal direction of the color-emitting structure 10 and in the width direction of the color-emitting structure 10. In the example shown in Figure 24, the color-emitting structure 10 has brightness and darkness such that the brightness at the ends in the width direction is lower than the brightness at the center in the width direction of the color-emitting structure 10. This brightness and darkness is caused by the shape of the side surface 100CS that houses the color-emitting structure 10.

[0094] The color-developing structure 10 shown in Figure 24 further includes a printed layer 13. Therefore, the color-developing structure 10 can display an image that combines the image from the structural layer and the image from the printed layer 13. In the example shown in Figure 24, the printed layer 13 of the color-developing structure 10 can display the string "Faster".

[0095] Figure 25 shows the cross-sectional structure of the color-developing structure 10 shown in Figure 24. As shown in Figure 25, the color-developing structure 10 comprises a printing layer 13, an adhesive layer 14, and a substrate 15, in addition to the color-developing structure 10 described earlier with reference to Figure 1. The adhesive layer 14 is located on the optical layer 12. The adhesive layer 14 is formed from various light-transmitting adhesive layers 14. The adhesive layer 14 is formed from, for example, an acrylic adhesive or a urethane adhesive. The adhesive layer 14 is transparent. The thickness of the adhesive layer 14 may be, for example, 10 μm or more and 100 μm or less.

[0096] The substrate 15 is a flat layer that supports the structural layer 11. The substrate 15 is made of a material that transmits light across the entire visible region, that is, a material that is transparent to light in the visible region. The substrate 15 may be, for example, a substrate made of synthetic quartz or a film made of synthetic resin. The synthetic resin may be, for example, polyethylene terephthalate. The thickness of the substrate 15 may be, for example, 10 μm or more and 100 μm or less.

[0097] The structural layer 11 is located on the substrate 15. The structural layer 11 has an uneven surface on the surface opposite to the surface in contact with the substrate 15. In the embodiment described above, the color-developing structure 10 may also include the substrate 15.

[0098] The printing layer 13 may be formed from various inks. The ink may contain, for example, at least one of a pigment and a dye. The printing layer 13 may exhibit a single color, or it may consist of a first portion having a first color and a second portion exhibiting a second color different from the first color. The printing layer 13 is formed, for example, on the surface of the substrate 15 where the structural layer 11 is located. As a result, the printing layer 13 is located between the substrate 15 and the structural layer 11. The printing layer 13 may also be located on the surface of the substrate 15 opposite to the surface where the structural layer 11 is located.

[0099] [Manufacturing method] The manufacturing method for the color-developing structure 10 will be described below. The structural layer 11 of the color-developing structure 10 is formed, for example, using an extrusion molding apparatus. The extrusion molding apparatus includes, for example, a die, a first roll, and a second roll. The die melts a synthetic resin for forming the structural layer 11 and extrudes the molten resin between the first roll and the second roll. The first roll has an outer surface with a textured pattern for forming the textured elements of the structural layer 11. The second roll has a flat outer surface. The first roll, together with the second roll, grips the synthetic resin extruded between the first and second rolls, and by extruding it in this way, the textured pattern of the first roll is transferred to the synthetic resin before curing. The structural layer 11 is formed when the synthetic resin after the transfer is cured.

[0100] Next, an optical layer 12 is formed on the surface 11F of the structural layer 11. The optical layer 12 is formed by various film deposition methods. The film deposition method for forming the optical layer 12 may be, for example, vapor deposition, sputtering, or CVD. As described above, if the optical layer 12 comprises a high refractive index layer 12a and a low refractive index layer 12b, the high refractive index layer 12a and the low refractive index layer 12b are alternately formed on the surface 11F of the structural layer 11 using one of the film deposition methods.

[0101] As described above, according to one embodiment of the color-developing structure, the following effects can be obtained. (1) The color-generating structure 10 is capable of displaying a pattern based on the contrast between the narrow diffusion region 11FN and the wide diffusion region 11FW.

[0102] (2) The monotony of the pattern displayed by the color-generating structure 10 is reduced, such as when it contains only regions of the same length in the second direction D2, and the complexity of the pattern is increased.

[0103] (3) In the second direction D2, the difference between the length LN of the narrow diffusion region 11FN and the length LW of the wide diffusion region 11FW does not become too large, so the pattern is easily displayed by the contrast between the narrow diffusion region 11FN and the wide diffusion region 11FW.

[0104] (4) If the length in the second direction D2 in the diffusion region group changes aperiodically for each diffusion region 11FN, 11FW, it is possible to display a pattern with aperiodicity throughout the entire diffusion region group.

[0105] (5) By having lengths of 10 μm or more for each of the major axis LA and the minor axis SA, diffraction of light incident on the multiple protrusions 11A is suppressed.

[0106] (6) By having the lengths of the long axis LA and the short axis SA be 200 μm or less, the protrusions 11A are less likely to be visible to an observer of the color-developing structure 10 when no magnifying tool is used.

[0107] (7) The ratio of the length of the minor axis SA (LSA) to the length of the major axis LA is 0.8 or less, which allows the convex portion 11A to diffuse light anisotropically.

[0108] (8) In the thickness direction of the structural layer 11, the dimensions of the protrusions 11A are within the range of 5 μm to 50 μm, which facilitates the formation of the protrusions 11A.

[0109] (9) Depending on the size of the protrusions 11AN and 11AW of each diffusion region 11FN and 11FW, it is possible to make the range in which light is scattered by the protrusion 11AW of the wide diffusion region 11FW larger than the range in which light is scattered by the protrusion 11AN of the narrow diffusion region 11FN.

[0110] (10) Depending on the orientation of the long axis LA in the protrusions 11AN and 11AW of each diffusion region 11FN and 11FW, it is possible to make the range in which light is scattered by the protrusion 11AW of the wide diffusion region 11FW larger than the range in which light is scattered by the protrusion 11AN of the narrow diffusion region 11FN.

[0111] (11) The color-producing structure 10 can exhibit a structural color corresponding to the refractive index of the dielectric layer constituting the optical layer 12.

[0112] The above-described embodiment can be implemented with the following modifications. [Absorbent layer] As shown in Figure 26, the color-generating structure 20 may include an absorption layer 16. The absorption layer 16 is located on the opposite side of the optical layer 12 from the structural layer 11. The absorption layer 16 absorbs at least a portion of the light transmitted through the optical layer 12. In the example shown in Figure 23, the color-generating structure 20 further includes a substrate 15 located between the absorption layer 16 and the structural layer 11.

[0113] The absorbing layer 16 absorbs at least a portion of the visible light other than the dominant color of the reflected light in the optical layer 12. The absorbing layer 16 may be a black layer that absorbs light in the entire visible region. In this case, the absorbing layer 16 is materialized as a layer containing a black dye. The absorbing layer 16 suppresses the reflection of light in wavelengths different from the dominant color of the reflected light in the optical layer 12 at the interfaces of each layer inside the color-producing structure 20, and at the interface between the color-producing structure 20 and the outside of the color-producing structure 20. As a result, the emission of light in wavelengths different from the dominant color of the reflected light in the optical layer 12 towards the observer is suppressed. Consequently, the vividness of the dominant color exhibited by the color-producing structure 20 is enhanced.

[0114] [Structural layer] As shown in Figures 27 and 28, the color-developing structure 30 may comprise two structural layers. Figure 27 is a perspective view showing only the first structural layer 31 and the second structural layer 32 of the color-developing structure 30. In Figure 27, the broad diffusion regions of each structural layer 31 and 32 are schematically shown by black lines, and the narrow diffusion regions of each structural layer 31 and 32 are schematically shown by white lines.

[0115] As shown in Figure 27, the first structural layer 31 comprises a plurality of narrow diffusion regions extending along the first direction D1 and a plurality of broad diffusion regions extending along the first direction D1. In the second direction D2, which is orthogonal to the first direction D1, the narrow diffusion regions and broad diffusion regions are arranged alternately. The second structural layer 32, similar to the first structural layer 31, comprises a plurality of narrow diffusion regions extending along the first direction D1 and a plurality of broad diffusion regions extending along the first direction D1. In the second direction D2, the narrow diffusion regions and broad diffusion regions are arranged alternately.

[0116] Between the first structural layer 31 and the second structural layer 32, in at least one of the multiple narrow diffusion regions and the multiple broad diffusion regions, the rules for the width along the second direction D2 set for each diffusion region are different. As a result, when the first structural layer 31 and the second structural layer 32 are superimposed, the color-producing structure 30 exhibits interference fringes due to the width rules set for each diffusion region in the first structural layer 31 and the width rules set for each diffusion region in the second structural layer 32.

[0117] The color-generating structure 30 comprises a first optical layer located on the first structural layer 31 and a second optical layer located on the second structural layer 32. The wavelength of light enhanced by interference in the first optical layer and the wavelength of light enhanced by interference in the second optical layer may be the same or different from each other.

[0118] Furthermore, in the color-developing structure 30, the first structural layer 31, the first optical layer, the second structural layer 32, and the second optical layer are stacked in the order described above. Between the first optical layer and the second structural layer 32, there is a planarization layer that fills in the irregularities of the first optical layer, thereby flattening the surface on which the second structural layer 32 is located.

[0119] Figure 28 schematically shows the pattern displayed by the color-emitting structure 30 in a plan view facing the surface 30F of the color-emitting structure 30. For the sake of explanation, in Figure 28, only the interference fringes IF formed by the first structural layer 31 and the second structural layer 32 are shown overlapping the surface 30F of the color-emitting structure 30.

[0120] As shown in Figure 28, when viewed from a viewpoint opposite the surface 30F of the color-developing structure 30, the color-developing structure 30 exhibits interference fringes (IF). Although not shown in Figure 25, the color-developing structure 30, like the color-developing structure 10 shown in Figure 9, displays a pattern of continuous hairlines formed by the first structural layer 31 and the first optical layer, and a pattern of continuous hairlines formed by the second structural layer 32 and the second optical layer. The interference fringes (IF) are formed when the patterns of continuous hairlines overlap in the thickness direction of the color-developing structure 30. [Explanation of symbols]

[0121] 10...Color-developing structure 11...Structural layer 12...Optical layer 11A... protruding part 11F…Surface 11FN…Narrow diffusion region 11FW… Widespread area

Claims

1. A structural layer having a surface, A color-generating structure comprising an optical layer located on the surface and having a shape that conforms to the surface, the optical layer reflecting light strengthened by interference, The surface includes a plurality of narrow diffusion regions and a plurality of broad diffusion regions. Each narrow diffusion region and each broad diffusion region extends along the first direction, In a second direction intersecting the first direction, the narrow diffusion region and the broad diffusion region are arranged alternately. The plurality of narrow diffusion regions include a narrow diffusion region having a first length in the second direction and a narrow diffusion region having a second length in the second direction, wherein the second length is different from the first length. The plurality of broad diffusion regions include a broad diffusion region having a third length in the second direction and a broad diffusion region having a fourth length in the second direction, wherein the fourth length is different from the third length. Each broad diffusion region comprises multiple uneven elements, which are either multiple protrusions or multiple recesses. Each narrow diffusion region comprises multiple uneven elements or flat surfaces. When viewed from a viewpoint opposite to the surface, the uneven elements have an elliptical shape or a polygonal shape inscribed in an ellipse. The aforementioned uneven element has a long axis and a short axis, The length of the aforementioned major axis is within the range of 10 μm to 200 μm. The ratio of the length of the minor axis to the length of the major axis is within the range of 0.1 to 0.

8. Color-producing structure.

2. In the second direction, The ratio of the minimum value in the length of the narrow diffusion region to the maximum value in the length of the broad diffusion region is 0.3 or more, and the ratio of the maximum value in the length of the narrow diffusion region to the maximum value in the length of the broad diffusion region is 1.0 or less, or The ratio of the minimum value in the length of the broad diffusion region to the maximum value in the length of the narrow diffusion region is 0.3 or more, and the ratio of the maximum value in the length of the broad diffusion region to the maximum value in the length of the narrow diffusion region is 1.0 or less. The color-developing structure according to claim 1.

3. At least one of the plurality of narrow diffusion regions and the plurality of broad diffusion regions is a group of diffusion regions. In the aforementioned group of diffusion regions, the length in the second direction changes aperiodically for each diffusion region. The color-developing structure according to claim 1 or 2.

4. In the thickness direction of the structural layer, the dimensions of the uneven elements are within the range of 5 μm to 50 μm. The color-developing structure according to claim 1.

5. Each narrow diffusion region comprises the plurality of uneven elements, Viewed from a viewpoint opposite to the aforementioned surface, The uneven elements in each broad diffusion region are larger than the uneven elements in each narrow diffusion region. The color-developing structure according to claim 1.

6. The aforementioned uneven element has a long axis and a short axis, Each narrow diffusion region comprises the plurality of uneven elements, The uneven elements in each broad diffusion region have the same shape as the uneven elements in each narrow diffusion region. Viewed from a viewpoint opposite to the aforementioned surface, The orientation of the major axis of the uneven element in each broad diffusion region intersects with the orientation of the major axis of the uneven element in each narrow diffusion region. The color-developing structure according to claim 1.

7. The optical layer comprises a plurality of dielectric layers, In the thickness direction of the optical layer, the refractive indices of adjacent dielectric layers are different from those of the other. The color-developing structure according to any one of claims 1 to 6.

8. The structural layer is further located on the opposite side from the optical layer, and comprises an absorbing layer that absorbs at least a portion of the light transmitted through the optical layer. The color-developing structure according to any one of claims 1 to 7.

Images