Color shift display body and method for manufacturing the same

Abstract

To provide a color shift display body capable of achieving optimization for each periodic component of a front face and a rear face without changing the height of an uneven structure of a relief type diffraction grating.SOLUTION: A color shift display body in which a color observed from a front face and a color observed from rear face are different, and which is formed by laminating a first transparent layer which is arranged on a front face side and has the first refractive index, a second transparent layer which is arranged on a rear face side and has the second refractive index, and a reflective layer arranged between the first transparent layer and the second transparent layer, where the reflective layer includes a pattern of an uneven structure having a first grating period affecting the first transparent layer and a second grating period affecting the second transparent layer, the first refractive index and the second refractive index are different, the first grating period and the second grating period are different, the product of the first refractive index and the first grating period is equal to the product of the second refractive index and the second grating period.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a color shifting display device using, for example, a relief type diffraction grating, and a method for producing the same. [Background technology]

[0002] Conventionally, a color shift display device has been known in which one surface of the uneven structure of a relief-type diffraction grating is designated as the front surface and the other opposing surface is designated as the back surface, and a difference is made between the periodic pitch on the front surface side and the periodic pitch on the back surface side, and by changing the angle between the diffracted light on the front surface side and the diffracted light on the back surface side, a color change is observed when the observation position is changed between the front surface side and the back surface side or when the display device is rotated 180 degrees. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-129096 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, this type of conventional color shifting display has the following problems.

[0005] That is, in a relief type diffraction grating, the optimal height of the relief structure is determined according to the grating period. However, in a conventional color shifting display, a single relief structure contains a periodic component on the front side and a periodic component on the back side.

[0006] For this reason, in conventional color shifting displays, the height of the uneven structure can only be optimized for either the periodic component on the front side or the periodic component on the back side, and it is not possible to optimize the height for the periodic components on both the front side and the back side.

[0007] The present invention has been made in consideration of the above circumstances, and aims to provide a color shifting display device and a manufacturing method thereof that can optimize the periodic components on both the front and back sides without changing the height of the uneven structure of the relief type diffraction grating. [Means for solving the problem]

[0008] In order to achieve the above object, the present invention takes the following measures.

[0009] That is, a first aspect of the present invention is a color shifting display device in which the color observed from the front side is different from the color observed from the back side, the color shifting display device being formed by laminating a first transparent layer having a first refractive index arranged on the front side, a second transparent layer having a second refractive index arranged on the back side, and a reflective layer arranged between the first transparent layer and the second transparent layer, the reflective layer including a pattern of a concave-convex structure having a first grating period acting on the first transparent layer and a second grating period acting on the second transparent layer, the first refractive index and the second refractive index being different, the first grating period and the second grating period being different, and the product of the first refractive index and the first grating period being equal to the product of the second refractive index and the second grating period.

[0010] A second aspect of the present invention is a color shifting display device of the first aspect, wherein the pattern of the uneven structure is repeated in the lattice arrangement direction, and a matching period, which is the length along the lattice arrangement direction from the point where the start point of a first lattice period coincides with the start point of a second lattice period to the point where the end point of the first lattice period coincides with the end point of the second lattice period, in the uneven structure repeated in the pattern, is equal to a first integer multiple of the first lattice period and a second integer multiple of the second lattice period, and the second integer is 1 greater than the first integer.

[0011] A third aspect of the present invention is a color shifting display device according to the second aspect, in which the duty ratio of the uneven surface structure repeats a monotonically increasing or decreasing pattern along the lattice arrangement direction for each matching cycle from the start point to the end point of the matching cycle.

[0012] A fourth aspect of the present invention is a color shifting display device in which the color observed from the front side is different from the color observed from the back side, the color shifting display device being formed by laminating a first transparent layer having a first refractive index, arranged on the front side, a second transparent layer having a second refractive index, arranged on the back side, and a reflective layer arranged between the first transparent layer and the second transparent layer, the reflective layer including a repetition of a pattern of a concave-convex structure having a first grating period acting on the first transparent layer, and a second grating period and a third grating period acting on the second transparent layer, the first refractive index and the second refractive index being different from each other, the second grating period and the third grating period being different from each other, the first refractive index and the second refractive index being different from each other, the second grating period and the third grating period being different from each other, the first refractive index and the second refractive index being different from each other, the second grating period and the third grating period being different from each other, the second grating period and the first transparent layer being different from each other, the third grating period and the first grating period being different from each other, the third grating period and the first grating period being different from each other, the third grating period and the first grating period being different from each other, the third grating period and the first grating period being different from each other, the third grating period and the first grating period being different from each other, the fourth grating period and the fourth grating period being different from each other, the fourth grating period and the fifth ... a color shifting display device in which the child period is different from the third grating period, but the grating arrangement directions of the first grating period, the second grating period, and the third grating period are the same, the product of the first refractive index and the first grating period is equal to the product of the second refractive index and the second grating period, the duty ratio of the uneven structure periodically repeats monotonically increasing or decreasing along the grating arrangement direction, the length along the grating arrangement direction of the uneven structure having the minimum and maximum duty ratios among the uneven structures acting on the second transparent layer is equal to the third grating period, and the length along the grating arrangement direction of each of the other uneven structures is equal to the second grating period.

[0013] A fifth aspect of the present invention is a color shifting display device according to any one of the first to fourth aspects, in which the unevenness height of the uneven structure in the stacking direction is constant.

[0014] A sixth aspect of the present invention is the color shifting display device of the second aspect, in which the lattice arrangement direction is perpendicular to the lamination direction.

[0015] A seventh aspect of the present invention is a method for manufacturing a color shifting display, comprising the steps of: applying a photosensitive resist material to a smooth substrate to form a resist material layer of uniform thickness; drawing a desired pattern of a concave-convex structure on the resist material layer by a charged particle beam; obtaining a structure having the desired pattern of a concave-convex structure by developing the resist material layer; using the structure as an original plate and producing a stamper from the original plate; and printing the pattern of the concave-convex structure on a first transparent layer having a first refractive index using the stamper. a step of replicating a pattern of a first transparent layer, a step of laminating a reflective layer on a first transparent layer, and a step of laminating a second transparent layer having a second refractive index on the reflective layer, wherein the first refractive index and the second refractive index are different, the pattern of the uneven structure has a first grating period acting on the first transparent layer and a second grating period acting on the second transparent layer, the first grating period and the second grating period are different, and the product of the first refractive index and the first grating period is equal to the product of the second refractive index and the second grating period. Effect of the Invention

[0016] According to the present invention, it is possible to provide a color shifting display device and a manufacturing method thereof that can optimize the periodic components on both the front and back sides without changing the height of the uneven structure of the relief type diffraction grating. [Brief description of the drawings]

[0017] [Figure 1] FIG. 1 is a cross-sectional view showing an example of the configuration of a color shifting display according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a conceptual diagram showing the function of a color shifting display according to an embodiment of the present invention. [Diagram 3] FIG. 3 is a conceptual cross-sectional view of a reflective layer for explaining the grating period of the reflective layer. [Figure 4] FIG. 4 is a schematic cross-sectional view corresponding to FIG. 3, of a reflective layer in a modified color shifting display according to an embodiment of the present invention. [Diagram 5]FIG. 5 is a flow chart showing a method for producing a color shifting display according to this embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] Hereinafter, each embodiment of the present invention will be described with reference to the drawings. The drawings are schematic or conceptual, and the relationship between the thickness and width of each part, the size ratio between parts, etc. are not necessarily the same as the actual ones. Even when the same part is shown, the dimensions and ratios of each part may be different depending on the drawing. In this specification and each drawing, elements similar to those described above with respect to the previous drawings are given the same reference numerals, and detailed explanations and duplicated explanations are omitted as appropriate.

[0019] Hereinafter, the best mode for carrying out the present invention will be described with reference to the drawings.

[0020] (Color shift display) First, a color shifting display according to an embodiment of the present invention will be described.

[0021] FIG. 1 is a cross-sectional view showing an example of the configuration of a color shifting display according to an embodiment of the present invention.

[0022] FIG. 2 is a conceptual diagram showing the function of a color shifting display according to an embodiment of the present invention.

[0023] As illustrated in FIG. 1, the color shifting display 10 of this embodiment has a flat plate shape having a front surface 11 and a back surface 21 parallel to the xy plane in the figure, and its cross-sectional structure is formed by stacking a transparent layer 12, a reflective layer 30, and a transparent layer 22 in that order from the top side (+z side) in the figure.

[0024] The transparent layer 12 is made of a material having a refractive index n1, and the transparent layer 22 is made of a material having a refractive index n2. The refractive index n1 and the refractive index n2 are different (n1≠n2).

[0025] The reflective layer 30 is made of a pattern of a concave-convex structure having a grating period A that acts on the transparent layer 12 and a grating period B that acts on the transparent layer 22. The grating period A is different from the grating period B (A ≠ B). Since the reflective layer 30 has low reflectance when left as a transparent material, a material with a high refractive index, such as a metal film, is evaporated onto the concave-convex surface.

[0026] The product of the refractive index n1 and the grating period A is equal to the product of the refractive index n2 and the grating period B (An1=Bn2). In this way, by selecting the refractive indices n1 and n2 of the transparent layers 12 and 22 in conjunction with each period to be color shifted, the diffraction efficiency of the diffracted light on the front and back of the color shifting display body 10 can be optimized.

[0027] With a color shifting display 10 configured in this manner, the color observed from the front surface 11 side (e.g., red) is different from the color observed from the back surface 21 side (e.g., green) as shown in FIG. 2(a).

[0028] Next, the grating periods A and B of the reflective layer 30 will be described in detail.

[0029] FIG. 3 is a conceptual cross-sectional view of a reflective layer for explaining the grating period of the reflective layer.

[0030] The pattern of the concave-convex structure of the reflective layer 30 is repeated in the lattice arrangement direction (x direction). The concave-convex height H of the concave-convex structure in the stacking direction (z direction) is constant. The stacking direction (z direction) and the lattice arrangement direction (x direction) are perpendicular to each other.

[0031] In a repeated pattern of uneven structures, the starting point S of the grating period A A and the starting point S of the lattice period B B From the point where these two points match (the leftmost point in Figure 3), the end point EA of lattice period A and the end point E of lattice period B are BThe matching period T, which is the length along the lattice arrangement direction (x direction) up to the point where A and B match, is equal to a first integer multiple of the lattice period A and a second integer multiple of the lattice period B, and the second integer is 1 greater than the first integer. In other words, when the first integer is m (≠ 0), the second integer is (m+1), and the relationships T=Am=B(m+1), A=T / m, B=T / (m+1) are established.

[0032] In addition, in the concave-convex structure, the start point S of the matching period T A ,S B From end point E A ,E B The duty ratio of the concave-convex structure repeats a monotonous increase or decrease for each matching period T along the grating arrangement direction (x direction).

[0033] For example, as shown in FIG. 3, in the case of the uneven structure on the transparent layer 12 (upper side in the figure), the start point S A From end point E A On the other hand, in the case of the uneven structure on the transparent layer 22 (lower side in the figure), the duty ratio of the uneven structure increases monotonically along the lattice arrangement direction (x direction) until the start point S of the matching period T. B From end point E B The duty ratio of the concave-convex structure monotonically decreases along the lattice arrangement direction (x direction) until the end point E of the matching period T in both the transparent layer 12 (upper side in the figure) side and the transparent layer 22 (lower side in the figure) side. A ,E B When it reaches, a new matching period T starts from there in the lattice arrangement direction (x direction). In this way, the pattern of the concave-convex structure is repeated for each matching period T.

[0034] Note that if the matching period T becomes fine enough to be on the wavelength level, the diffracted light of the matching period T will dominate the whole and blazing will progress, so the matching period T is set to be much larger than the wavelength, and the grating periods A and B are set to the wavelength level. By setting the grating periods A and B to the wavelength level size, the components are concentrated in the diffracted light of the grating period A and the diffracted light of the grating period B, and the observation colors according to each diffraction angle can be visually confirmed, and the difference between the observation color of the grating period A and the observation color of the grating period B can be confirmed.

[0035] In color shifting display 10, if the periodic sizes of grating period A and grating period B are too large or too small, the color shift effect weakens, so it is necessary to optimize them. Examples of sizes at which a noticeable color shift effect is obtained, which were obtained through experiments based on this principle, are as follows.

[0036] Matching period T≧4000nm Lattice period A=800~1200nm Lattice period B=700~1100nm Integer m≧5 Next, the effects of the color shifting display according to the embodiment of the present invention will be described.

[0037] In the color shifting display 10, the element structure for obtaining the optical effect is formed of transparent layers 12 and 22, which are arranged on the front and back sides, respectively, so that light incident from either the front or back can reach the uneven structure of the reflective layer 30.

[0038] Furthermore, by selecting the refractive indices n1 and n2 of the transparent layers 12 and 22 in conjunction with each period of color shifting, the diffraction efficiency of the diffracted light on the front and back of the color shifting display body 10 can be optimized.

[0039] Generally, the diffraction efficiency is optimized by changing the unevenness height H of the relief structure and adjusting the optical path length. Therefore, in a configuration in which two periodic components are integrated, such as a periodic component having a grating period A on the front surface 11 side and a periodic component having a grating period B on the back surface 21 side, as in the case of the front-back type color shifting display 10, the unevenness height H of the unevenness structure of the reflective layer 30 is the same when viewed from both the front surface 11 side and the back surface 21 side, and therefore the optical path length cannot be adjusted by changing the unevenness height H for each periodic component.

[0040] However, in the color shifting display 10 according to the present embodiment, even if the unevenness height H cannot be changed, the optical path length can be adjusted by changing the difference between the refractive index of the transparent layer 12 on the front surface 11 side and the refractive index of the transparent layer 22 on the back surface 21 side. This makes it possible to change the optical path length on the front surface 11 side and the back surface 21 side even if the unevenness height H of the reflective layer 30 cannot be changed, and makes it possible to adjust the optical path length to an optimum length for each periodic component.

[0041] As a result, in the color shifting display 10 of this embodiment, as shown in Figure 2(a), the diffraction effect on front surface 11 is due to the uneven slopes on the front surface 11 side, and for example, red diffracted light is emitted, whereas when the display is turned upside down, the diffraction effect on back surface 21 is due to the uneven slopes on the back surface 21 side, and for example, green diffracted light is emitted. In this way, by switching the acting slopes between front surface 11 and back surface 21, a color change due to the front and back can be achieved.

[0042] Although there are other examples of methods for obtaining different optical effects on the front and back, the color shifting display device 10 of this embodiment has a simple structure with few elements that make up the layers, and has the advantage that the manufacturing process can be simplified, as will be described later.

[0043] (Modification of color shift display) Next, modified examples of the color shifting display according to the embodiment of the present invention will be described.

[0044] As described with reference to FIG. 3, in the uneven structure of the reflective layer 30 of the color shifting display 10, the start point S A ,S B From end point E A ,E B The duty ratio of the uneven structure monotonically increases or decreases along the lattice arrangement direction (x direction) until the starting point S A ,S B and end point E A ,E B The finest uneven structure is present in the surface of the substrate. The finer the uneven structure, the more difficult it is to reproduce.

[0045] Therefore, in this modified example, the starting point S A ,S B and end point E A ,E B In this case, the grating period B at the start and end points of the matching period T is replaced with a grating period C different from the grating period B so that the difference between the grating periods A and B does not become too small and to the extent that the grating periods A and B are not adversely affected. This will be described in detail below with reference to FIG. 4.

[0046] FIG. 4 is a schematic cross-sectional view corresponding to FIG. 3, of a reflective layer in a modified color shifting display according to an embodiment of the present invention.

[0047] That is, in the modified color shifting display of this embodiment, among the unevenness structures acting on the transparent layer 22, the length along the lattice arrangement direction (x direction) of the unevenness structures having the minimum and maximum duty ratios is equal to the lattice period C, and the length along the lattice arrangement direction (x direction) of each of the other unevenness structures is equal to the lattice period B. In other words, among the unevenness structures acting on the transparent layer 22, the start point S of the matching period T B and end point E B In this case, the lattice period B is changed to C, which is different from B (B ≠ C).

[0048] The transparent layer 12 is made of a material having a refractive index n1, and the transparent layer 22 is made of a material having a refractive index n2. The refractive index n1 is different from the refractive index n2 (n1≠n2), and the reflective layer 30 is made of a pattern of a concave-convex structure having a grating period A acting on the transparent layer 12 and a grating period B acting on the transparent layer 22. The grating period A is different from the grating period B (A≠B), and the product of the refractive index n1 and the grating period A is equal to the product of the refractive index n2 and the grating period B (An1=Bn2), as in the color shifting display 10, but the relationship T=Am=B(m+1), B=T / (m+1) does not hold, and the relationship T=Am=B(m-1)+2C holds.

[0049] In this way, by replacing the grating period B at the start and end points of the matching period T with a grating period C that is different from the grating period B in a proportion that is acceptable to the grating periods A and B, a color shifting display 10 that is easier to reproduce can be obtained.

[0050] (Manufacturing method of color shifting display) Next, a method for producing the color shifting display according to this embodiment will be described.

[0051] FIG. 5 is a flow chart showing a method for producing a color shifting display according to this embodiment.

[0052] That is, the manufacturing method of the color shifting display 10 is to apply a photosensitive resist material to a smooth substrate (a glass substrate is generally used) to form a resist material layer with a uniform thickness (S1). As the photosensitive resist material, a known positive or negative material can be used.

[0053] Next, a pattern of a desired relief structure is written on the resist material layer by using a charged particle beam (S2).

[0054] The uneven structure is not rectangular, but has corners that are blurred to be round and smooth, as exemplified in Figures 1 and 2. This is because, when the cross section of the uneven structure is rectangular wave-like (a cross section with steep sides, horizontal upper and lower bases, and corners), the periodic component on the front surface 11 side acts on both the front surface 11 side and the back surface 21 side, eliminating the difference in optical action when viewed from the front surface 11 side and the back surface 21 side.

[0055] By sloping the sides of the uneven structure and rounding off the corners, the difference in the uneven structure between the front surface 11 and the back surface 21 can be made clearer. Combined with the fact that the slope directions on the front surface 11 and the back surface 21 are opposite, it is possible to make combined use of the reflection effect, bringing the grating period A closer to the front surface 11 side and the grating period B closer to the back surface 21 side, resulting in different optical effects on the front surface 11 side and the back surface 21 side.

[0056] Next, the resist material layer is developed to obtain a structure having a desired pattern of a concave-convex structure (S3). The corners of the concave-convex structure may be blurred to be round and smooth, as described in step S2, in step S3 instead of step S2.

[0057] Next, the structure is used as an original plate, and a metal stamper is produced from the original plate by photolithography using a method such as electroforming (S4). Electroforming is a type of surface treatment technology in which an object to be electroformed is immersed in a specific aqueous solution, and an electric current is passed through it to form a metal film on the object by the reducing power of electrons. By using such a method, it is possible to accurately replicate the fine uneven structure provided on the surface of the original plate. Note that the surface of the object to be electroformed needs to be electrically conductive, but since photosensitive resists generally do not conduct electricity, a thin metal film is provided in advance on the surface of the structure by sputtering, vapor phase deposition such as vacuum deposition, or the like, before electroforming.

[0058] In the above, photolithography is used as a method for producing the master plate, but other methods such as machining the surface of a metal or the like by cutting, etching, etc. can also be used. By using such methods, it is possible to directly machine the surface of a metal plate, and in this case, a metal stamper can be directly produced without having to produce a metal stamper by a method such as electroforming.

[0059] Next, a stamper is used to replicate the pattern of the relief structure on the transparent layer 12, which is the relief structure formation layer on the surface 11 side (S5). Specifically, a metal stamper is attached to the relief structure formation layer on the surface 11 side, and in this state, heat and pressure are applied or light or electron beams are irradiated, and then the metal stamper is peeled off from the resin layer to obtain a relief structure formation layer having a relief structure. The transparent layer 12 may be provided on the substrate, but it does not have to be provided on the substrate.

[0060] In addition, for the resin of transparent layer 12, which is the relief structure forming layer on the front surface 11 side, and the resin of transparent layer 22, which is the relief structure forming layer on the back surface 21 side to be laminated in step S7 described later, two types of transparent resins having different refractive indexes n1, n2 are selected in accordance with the grating periods A, B of the uneven structure so that the aforementioned relationship An1 = Bn2 holds.

[0061] For example, if the lattice period A of the uneven structure acting on the front surface 11 side is 900 nm and the lattice period B of the uneven structure acting on the back surface 21 side is 800 nm, a fluorine-based resin (refractive index 1.35 to 1.42) can be selected as the material for the transparent layer 12 on the front surface 11 side, and a material with a higher refractive index than the fluorine-based resin (refractive index 1.35 to 1.42), such as polyvinyl alcohol (refractive index 1.49 to 1.53), can be selected as the material for the transparent layer 22 on the back surface 21 side.

[0062] Next, a metal such as aluminum or a dielectric is deposited in a single layer or multiple layers on the relief structure forming layer (transparent layer 12) by a vapor phase deposition method such as vacuum deposition or sputtering, to form a reflective layer 30 (S6).

[0063] Next, the transparent layer 22 on the back surface 21 side is laminated on the reflective layer 30 (S7). In this manner, the color shifting display body 10 can be manufactured. The order of processing the front surface 11 side and the back surface 21 side may be reversed. Furthermore, the color shifting display body 10 manufactured as described above can further be provided with various known functional layers, such as an intermediate layer, a printed layer, a protective layer, an adhesive layer, or an adhesive layer, as appropriate, to the extent that the refractive index of the transparent layers 12, 22 is not affected.

[0064] Such color shifting displays 10 can be used alone or in combination. When using multiple color shifting displays 10, for example, multiple color shifting displays 10 each having different periodic components or directions of the concave-convex structure can be manufactured and multiple color shifting displays 10 can be arranged in a composite manner to realize a more varied multicolor expression.

[0065] The color shifting display 10 can also be attached to some kind of article. For example, the color shifting display 10 can be made in the form of a transfer foil and attached to an article. Furthermore, it can be applied to an article with a window or a transparent card, and used to verify the front and back.

[0066] Although the best mode for carrying out the present invention has been described above with reference to the attached drawings, the present invention is not limited to such a configuration. Within the scope of the technical idea of ​​the invention defined in the claims, a person skilled in the art may conceive of various modifications and alterations, and it is understood that such modifications and alterations also belong to the technical scope of the present invention. [Explanation of symbols]

[0067] 10. Color shifting display 11...Surface 12...Transparent layer 21...Back side 22·Transparent layer 30·Reflective layer A,B,C... Lattice period E A,E B End point H: Height of unevenness n1, n2... refractive index S A ,S B ·Starting point T··Match period

Claims

1. A color shifting display device in which the color observed from the front side is different from the color observed from the back side, a first transparent layer disposed on the front surface side and having a first refractive index; a second transparent layer disposed on the back surface side and having a second refractive index; The first transparent layer and the second transparent layer are laminated together, and a reflective layer is disposed between the first transparent layer and the second transparent layer. the reflective layer includes a pattern of a relief structure having a first grating period acting on the first transparent layer and a second grating period acting on the second transparent layer; the first refractive index and the second refractive index are different, the first grating period and the second grating period are different, A color shifting display, wherein the product of the first refractive index and the first grating period is equal to the product of the second refractive index and the second grating period.

2. The pattern of the relief structure is repeated in a lattice arrangement direction, 2. The color shifting display of claim 1, wherein in the uneven structure repeated in the pattern, a matching period, which is a length along the lattice arrangement direction from a point where a start point of the first grating period coincides with a start point of the second grating period to a point where an end point of the first grating period coincides with an end point of the second grating period, is equal to a first integer multiple of the first grating period and a second integer multiple of the second grating period, and the second integer is 1 greater than the first integer.

3. 3. The color shifting display according to claim 2, wherein the duty ratio of the uneven structure repeats a monotonous increase or decrease for each matching cycle along the lattice arrangement direction from the start point to the end point of the matching cycle.

4. A color shifting display device in which the color observed from the front side is different from the color observed from the back side, a first transparent layer disposed on the front surface side and having a first refractive index; a second transparent layer disposed on the back surface side and having a second refractive index; The first transparent layer and the second transparent layer are laminated together, and a reflective layer is disposed between the first transparent layer and the second transparent layer. the reflective layer includes a repetition of a pattern of a concave-convex structure having a first grating period acting on the first transparent layer, and a second grating period and a third grating period acting on the second transparent layer; the first refractive index and the second refractive index are different, the first grating period and the second grating period are different, and the second grating period and the third grating period are different, but the first grating period, the second grating period, and the third grating period have the same grating arrangement direction; the product of the first refractive index and the first grating period is equal to the product of the second refractive index and the second grating period; the duty ratio of the concave-convex structure periodically repeats a monotonous increase or decrease along the grating arrangement direction; A color shifting display device, wherein, among the unevenness structures acting on the second transparent layer, the length along the lattice arrangement direction of the unevenness structures having the minimum and maximum duty ratios is equal to the third lattice period, and the length along the lattice arrangement direction of each of the other unevenness structures is equal to the second lattice period.

5. 5. The color shifting display according to claim 1, wherein the unevenness of the uneven structure is constant in the stacking direction.

6. 3. The color shifting display of claim 2, wherein the lattice arrangement direction is perpendicular to the lamination direction.

7. A method for producing a color shifting display, comprising the steps of: applying a photosensitive resist material to a flat substrate to form a resist material layer having a uniform thickness; writing a desired pattern of relief structure in the resist material layer by a charged particle beam; a step of developing the resist material layer to obtain a structure having the desired relief pattern; using the structure as a master, and producing a stamper from the master; using the stamper to replicate a pattern of the relief structure on a first transparent layer having a first refractive index; depositing a reflective layer on the first transparent layer; and depositing a second transparent layer having a second refractive index on the reflective layer; the first refractive index and the second refractive index are different, the pattern of the relief structure has a first grating period acting on the first transparent layer and a second grating period acting on the second transparent layer, the first grating period and the second grating period are different, A method of making a color shifting display, wherein the product of the first refractive index and the first grating period is equal to the product of the second refractive index and the second grating period.

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