Optical element

Abstract

Optical element (10, 50, 110, 160) with a transmission diffraction section (20, 60, 70, 80, 90, 100, 120, 130, 140, 150, 170), comprising a plurality of reflective sections (12, 12a, 31, 41, 61, 61a, 71, 71a, 81, 81a, 91, 91a, 101, 101a, 121, 131, 141, 151, 171) arranged at equal intervals along a given axis, each of the reflective sections reflecting light contained in visible light, and the light reflected by the reflective sections forming a reflection image, and a plurality of transmitting sections (13, 62, 72, 82, 92, 102, 122, 132, 142, 152, 172), each of which is clamped by two corresponding reflecting sections adjacent to each other along the given axis, wherein the transmitting sections transmit the visible light, wherein at least a part of each reflecting section forms the reflection image by reproducing a reflection angle of the light reflected by the reflecting sections that is different from an angle of light incident on the reflecting sections, The transmission diffraction section forms a multitude of diffraction patterns with different colors using diffracted light, which is generated by diffracting light transmitted through the transmitting sections in a predetermined direction. at least part of each reflective section (12, 12a) has a non-periodic uneven structure, The non-periodic uneven structure scatters visible light that falls upon it, and The scattered light emitted from the non-periodic, uneven structure forms the reflection image.

Description

Technical field

[0001] The present invention relates to an optical element. State of the art

[0002] Items requiring protection against counterfeiting, such as securities, certificates, and high-end branded products, are known to incorporate optical elements that prevent counterfeiting. These optical elements provide optical effects that are difficult to reproduce. Examples include holograms, diffraction gratings, and multilayer interference films or foils. These optical elements have minute or microfine structures, or complex layered structures, that hinder analysis of the optical element's structure. This prevents counterfeiting of the optical elements, thereby limiting the counterfeiting of items containing such optical elements.

[0003] An optical element such as a hologram comprises a reflective layer in contact with a diffraction structure to enhance the optical effect of the element. With such a structure, the difficulty of reproducing the hologram can be increased by shaping the reflective layer with a predetermined pattern (see, for example, patent document 1). State-of-the-art documents, patent documents

[0004] Patent document 1: Japanese published patent publication number JP 2003-255115 A

[0005] From US patent 2008 / 0304004A1, an optical element, a liquid crystal device, an electronic device, a manufacturing process for an optical element, and a manufacturing process for a liquid crystal device are known. The optical element comprises a diffraction-functional layer for diffracting at least a portion of the incident light and a grating arranged on a first surface of the diffraction-functional layer and having a plurality of wires. The first surface comprises a plurality of first regions and a plurality of second regions. The first regions and the second regions differ from each other in height above a second surface of the diffraction-functional layer as a surface relative to the first surface. Steps are provided at the boundaries between the first regions and the second regions. Summary of the invention: Problems that this invention is intended to solve

[0006] To increase the difficulty of reproducing the optical effects of optical elements, it is desirable for a single optical element to provide additional optical effects. Adding optical effects to an optical element is desirable not only for an optical element used to prevent counterfeiting of objects, as described above, but also for an optical element attached to an object for decoration and for an optical element valued for its own aesthetic quality.

[0007] It is an object of the present invention to provide an optical element that provides additional optical effects. Facilities to solve the problem

[0008] To achieve the aforementioned objective and according to one aspect of the present invention, an optical element is provided comprising a transmission diffraction section. The transmission diffraction section includes a plurality of reflective sections and a plurality of transmissive sections. The reflective sections are arranged at equal intervals along a given axis. Each of the reflective sections reflects light contained in visible light, and the light reflected by the reflective sections forms a reflection image. The transmissive sections are each clamped (or wedged or supported) between two corresponding reflective sections that are adjacent to each other along the given axis. The transmissive sections transmit the visible light.At least a portion of each reflecting section forms the reflection pattern by reproducing a reflection angle of the light reflected by the reflecting sections that differs from the angle of incident light. The transmission diffraction section forms a multitude of diffraction patterns of different colors using diffracted light generated by diffracting light transmitted through the transmitting sections in a predetermined direction. At least a portion of each reflecting section has a non-periodic uneven structure. The non-periodic uneven structure scatters visible light incident upon it. The scattered light emitted by the non-periodic uneven structure forms the reflection pattern.

[0009] Furthermore, an optical element is provided that includes a transmission diffraction section. The transmission diffraction section comprises a plurality of reflecting sections and a plurality of transmissive (or transmitting) sections. The reflecting sections are arranged at equal intervals along a given axis. Each of the reflecting sections reflects light contained in visible light, and the light reflected by the reflecting sections forms a reflection image. The transmitting sections are each sandwiched between two corresponding reflecting sections that are adjacent to each other along the given axis. The transmitting sections transmit the visible light.At least a portion of each reflecting section forms the reflection pattern by reproducing a reflection angle of the light reflected by the reflecting sections that differs from the angle of incident light. The transmission diffraction section forms a multitude of diffraction patterns of different colors using diffracted light generated by diffracting light transmitted by the transmitting sections in a predetermined direction. At least a portion of each reflecting section has a periodic uneven structure with a predetermined periodicity. The periodic uneven structure diffractes visible light incident on it in a predetermined direction. Diffracted light emitted by the periodic uneven structure forms the reflection pattern.

[0010] Through the aspect of the optical element described above, a single optical element provides images formed by the transmitted light, which have different colors, in addition to a reflected image formed by the reflected light. In other words, additional optical effects are added to the single optical element. Brief description of the drawings Fig. Figure 1 is a perspective view showing the structure of an optical element according to a first embodiment of the present invention. Fig. Figure 2 is a cross-sectional view showing the cross-sectional structure in a ZY plane of the optical element of the first embodiment. Fig. Figure 3 is a cross-sectional view showing the cross-sectional structure in a ZX plane of the optical element of the first embodiment. Fig. Figure 4 is a top view showing the planar structure of the optical element according to the first embodiment as seen along the Z-axis. Fig. Figure 5 is an operating diagram showing the optical effect of a reflection of the light incident on the optical element of the first embodiment. Fig. Figure 6 is an operating diagram showing the optical effect of a transmission of the light incident on the optical element of the first embodiment. Fig. Figure 7 is a process view showing a step in a method for manufacturing the optical element of the first embodiment. Fig. Figure 8 is a process view showing a step in the procedure for manufacturing the optical element of the first embodiment. Fig. Figure 9 is a process view showing a step in the procedure for manufacturing the optical element of the first embodiment. Fig. Figure 10 is a process view showing a step in the procedure for manufacturing the optical element of the first embodiment. Fig. Figure 11 is a perspective view showing the structure of an upper transparent plastic layer of a modification of the first embodiment. Fig. Figure 12 is a perspective view showing the structure of an upper transparent plastic layer of a modification of the first embodiment. Fig. Figure 13 is a top view showing the planar structure of the optical element of a modification of the first embodiment as seen along the Z-axis. Fig. Figure 14 is a top view showing the planar structure of the optical element of a modification of the first embodiment as seen along the Z-axis. Fig. Figure 15 is a top view showing the planar structure of the optical element of a modification of the first embodiment as seen along the Z-axis. Fig. Figure 16 is a top view showing the planar structure of the optical element of a modification of the first embodiment as seen along the Z-axis. Fig. Figure 17 is a top view showing the planar structure of the optical element of a modification of the first embodiment as seen along the Z-axis. Fig. Figure 18 is a process view showing a step in a manufacturing process of a modification of the first embodiment. Fig. Figure 19 is a process view showing a step in the manufacturing process of the modification of the first embodiment. Fig. Figure 20 is a process view showing a step in the manufacturing process of the modification of the first embodiment. Fig. Figure 21 is a process view showing a step in the manufacturing process of the modification of the first embodiment. Fig. Figure 22 is a perspective view showing the structure of an optical element according to a second embodiment of the present invention. Fig. Figure 23 is a cross-sectional view showing the cross-sectional structure in a ZY plane of the optical element of the second embodiment. Fig. Figure 24 is a cross-sectional view showing the cross-sectional structure in a ZX plane of the optical element of the second embodiment. Fig. Figure 25 is a top view showing the planar structure of the optical element according to the second embodiment as seen along the Z-axis. Fig. Figure 26 is an operating diagram showing the optical effect of a reflection of the light incident on the optical element of the second embodiment. Fig. Figure 27 is an operating diagram showing the optical effect of a transmission of the light incident on the optical element of the second embodiment. Fig. Figure 28 is a perspective view showing the structure of an optical element according to a third embodiment of the present invention. Fig. Figure 29 is a partial cross-sectional view showing the cross-sectional structure in a ZY plane of the optical element of the third embodiment. Fig. Figure 30 is a cross-sectional view showing the cross-sectional structure in a ZX plane of the optical element of the third embodiment. Fig. Figure 31 is a top view showing the planar structure of the optical element according to the third embodiment as seen along the Z-axis. Fig. Figure 32 is an operating diagram showing the optical effect of a reflection of the light incident on the optical element of the third embodiment. Fig. Figure 33 is an operating diagram showing the optical effect of a transmission of the light incident on the optical element of the third embodiment. Fig. Figure 34 is a top view showing the planar structure of the optical element according to a fourth embodiment of the present invention as seen along the Z-axis. Fig. Figure 35 is a top view showing the planar structure of the optical element according to a modification of the fourth embodiment as seen along the Z-axis. Fig. Figure 36 is a top view showing the planar structure of the optical element according to a modification of the fourth embodiment as seen along the Z-axis. Fig. Figure 37 is a top view showing the planar structure of the optical element according to a fifth embodiment of the present invention as seen along the Z-axis. Fig. Figure 38 is a top view showing the planar structure of the optical element according to a modification of the fifth embodiment as seen along the Z-axis. Fig. Figure 39 is a top view showing the planar structure of the optical element according to a modification of the fifth embodiment as seen along the Z-axis. Fig. Figure 40 is a top view showing the planar structure of the optical element according to a modification of the fifth embodiment as seen along the Z-axis. Fig. Figure 41 is a top view showing the planar structure of the optical element according to a sixth embodiment of the present invention as seen along the Z-axis. Fig. Figure 42 is a top view showing the planar structure of the optical element according to a modification of the sixth embodiment as seen along the Z-axis. Fig. Figure 43 is a top view showing the planar structure of the optical element according to a seventh embodiment of the present invention as seen along the Z-axis. Fig. Figure 44 is a top view showing the planar structure of the optical element according to a modification of the seventh embodiment as seen along the Z-axis. Methods for carrying out the invention; First embodiment

[0011] Referring to Fig. Sections 1 to 10 below describe an optical element according to a first embodiment. The following description details the structure of the optical element, its operation, and a method for manufacturing it, in that order. Structure of the optical element

[0012] Referring to Fig. Sections 1 to 4 below describe the structure of the optical element. Fig. 1 and Fig. 4. For the sake of simplicity in explaining the structure of the optical element, an upper transparent plastic layer formed on the reflective sections is not shown. Furthermore, to illustrate the positions of the reflective sections relative to the lower transparent plastic layer, the reflective sections are marked with dots in Fig. 1 and Fig. 4 shaded. Furthermore, the uneven structure formed on the surface of the lower transparent plastic layer is shown for illustrative purposes in Fig. 1 not shown.

[0013] As in Fig. As shown in Figure 1, an optical element 10 comprises an upper transparent plastic layer, a lower transparent plastic layer 11, a surface 11s that is a surface of the lower transparent plastic layer 11, and a plurality of reflective sections 12 formed between the upper transparent plastic layer and the lower transparent plastic layer 11. The optical element 10 comprises a plurality of transmitting sections 13. Each transmitting section 13 comprises a first section, which is a section of the upper transparent plastic layer clamped (or wedged or supported) between two reflective sections 12, and a second section, which is a section of the lower transparent plastic layer 11 clamped between two reflective sections 12. The second section is opposite the first section.The optical element 10 comprises a transmission diffraction section 20, which is formed by the reflecting sections 12 and the transmitting sections 13.

[0014] The reflective sections 12 reflect visible light and reflect at least a portion of wavelengths between 400 nm and 700 nm inclusive. The transmittance of the reflective sections 12 is preferably less than 30%. The transmitting sections 13 transmit at least portions of wavelengths between 400 nm and 700 nm inclusive, and the transmittance of the transmitting sections 13 is preferably 70% or more.

[0015] The reflective sections 12 can be made of a metal such as Al, Sn, Cr, Ni, Cu, Au, and Ag, or a mixture such as an oxide of a metal selected from this group of metals. From the materials listed above, the reflective sections 12 are preferably made of a material whose reflectance and transparency change, for example, when the material dissolves or corrodes, or when the material's properties change. Furthermore, two or more materials from the group of metals and the group of metal mixtures or alloys listed above can be used.

[0016] To change the reflectance or transmittance of the reflective sections 12 by dissolving the material, the material selected from the group of metals and the group of metal oxides listed above can be etched. The etching process can use an agent such as an acid, an alkali, an organic solvent, an oxidant, or a reducing agent.

[0017] To change the reflectance or transmittance of the reflective sections 12 by changing the properties of the material, for example copper can be oxidized by means of an oxidant and changed to cuprooxide, or aluminum can be oxidized by means of an oxidant and changed to boehmite.

[0018] The reflective sections 12 can be made of a material selected from the group of metals and metal alloys listed above. Additionally, the selected material can be subjected to the processing described above. The material and processing can be chosen according to the optical properties required for the optical element 10 and its durability during use, such as weather resistance and adhesion between the layers.

[0019] The thin film forming the reflective sections 12 preferably has a uniform surface density. Therefore, the thin film forming the reflective sections 12 is preferably formed by a dry coating process. The dry coating process can be, for example, vacuum deposition, sputtering, or CVD.

[0020] The material for the reflective sections 12 is not limited to materials with a metallic luster or a predetermined color as described above and may be a transparent material. Transparent materials are listed below. The example material for the reflective sections 12 includes Sb₂O₃, Fe₂O₃, TiO₂, CdS, CeO₂, ZnS, PbCl₂, CdO, Sb₂O₃, WO₃, SiO, Si₂O₃, In₂O₃, PbO, Ta₂O₃, ZnO, ZrO₂, MgO, SiO₂, Si₂O₂, MgF₂, CeF₃, CaF₂, AlF₃, Al₂O₃, and GaO.

[0021] The transparent material of the reflective sections 12 can be an organic polymer. Examples of organic polymers that can be used to form the reflective sections 12 include polyethylene (“polyethylene”), polypropylene (“polypropylene”), polytetrafluoroethylene (“polytetrafluoroethylene”), polymethyl methacrylate (“polymethyl methacrylate”), and polystyrene (“polystyrene”).

[0022] Furthermore, the reflective sections 12 can be made of reflective inks in which high refractive index resin or high refractive index filler is dispersed. The material of the reflective sections 12 can be selected from the materials listed above according to the reflective properties or durability required for the optical element 10.

[0023] The transmitting sections 13, i.e., the upper transparent plastic layer and the lower transparent plastic layer 11 that form the transmitting sections 13, can be made of various resins that meet the transmittance requirements as described above. For example, thermosetting resin and ultraviolet curable resin can be used. As long as the transmittance requirements described above are met, the upper transparent plastic layer and the lower transparent plastic layer 11 can have a matte finish or be white.

[0024] The lower transparent plastic layer 11 can be in the form of a rectangular plate extending two-dimensionally along the X-axis, which is an example of a given axis, and the Y-axis, which extends perpendicular to the X-axis. Each of the reflective sections 12 is shaped like a strip extending along the Y-axis, which serves as a given axis. The reflective sections 12 are arranged at equal intervals along the X-axis. In the same way as the reflective sections 12, each of the transmitting sections 13 is shaped like a strip extending along the Y-axis. The transmitting sections 13 are arranged at equal intervals along the X-axis.

[0025] As in Fig. As shown in Figure 2, the optical element 10 further comprises a plurality of protective sections 14, each of which is arranged between the surface 11s of the lower transparent plastic layer 11 and a corresponding reflective section 12. Like the reflective sections 12, each of the protective sections 14 is shaped like a strip extending along the Y-axis. The protective sections 14 are arranged at equal intervals along the X-axis. The entire area of ​​each protective section 14 overlaps the entire area of ​​the corresponding reflective section 12 as seen along the Z-axis. The protective sections 14 protect the reflective sections 12 from wear and corrosion that would otherwise be caused by agents during the manufacture of the optical element 10.

[0026] Therefore, the wear resistance and resistance to the agent of the protective sections 14 is preferably higher than that of the reflective sections 12. However, even if the wear resistance and resistance to the agent of the protective sections 14 are lower than those of the reflective sections 12, the protective sections 14 covering a surface of the respective reflective sections 12 still protect the reflective sections 12.

[0027] The protective sections 14 can act as the etching mask used when the reflective sections 12 are formed by an etching process. When the protective sections 14 act as the etching mask, it is preferred that the protective sections 14 are not dissolved by at least one liquid that dissolves the reflective sections 12, or that the rate at which the liquid dissolves the protective sections 14 is lower than the rate at which the liquid dissolves the reflective sections 12.

[0028] As in the case of the reflective sections 12, the thin film for forming the protective sections 14 preferably has a uniform surface density. The thin film for forming the protective sections 14 can be formed by a dry coating process such as vacuum deposition, CVD, and sputtering. Such processes allow for adjustment of the thin film thickness for the protective sections 14, the film formation rate, the number of layers, and the optical thickness of the film. Of the dry coating processes listed above, vacuum deposition allows the material used to move from the vapor source to the substrate in straight lines. Therefore, vacuum deposition is the preferred dry coating process.

[0029] The protective sections 14 may be made of any material that can be applied by a dry coating process. For example, one or more materials selected from the group of metals and the group of metal alloys listed above in relation to the reflective sections 12 may be used to form the protective sections 14.

[0030] As with the reflective sections 12, the protective sections 14 can be made of a transparent material. Examples of transparent materials for the protective sections 14 include Sb₂O₃, Fe₂O₃, Fe₃O₄, TiO₂, Ti₂O₃, CdS, CeO₂, ZnS, PbCl₂, CdO, Sb₂O₃, WO₃, SiO₂, Si₂O₃, In₂O₃, PbO, Ta₂O₃, ZnO, ZrO₂, MgO, SiO₂, Si₂O₂, MgF₂, CeF₃, CaF₂, AlF₃, Al₂O₃, and GaO.

[0031] The transparent material used to form the protective sections 14 can be an organic polymer. Examples of organic polymers used to form the protective sections 14 include polyethylene (“polyethylene”), polypropylene (“polypropylene”), polytetrafluoroethylene (“polytetrafluoroethylene”), polymethyl methacrylate (“polymethyl methacrylate”), and polystyrene (“polystyrene”).

[0032] If the protective sections 14 act as an etching mask, they can be formed in a predetermined pattern by photolithography. In this case, a negative or positive photoresist is applied to the thin film to form the protective sections 14, and the photoresist is then exposed to a pattern of light. The thin film is then etched to form the protective sections 14 using the photoresist as an etching mask. This forms the protective sections 14, acting as an etching mask, onto portions of the thin film to form the reflective sections 12. The thin film is then etched to form the reflective sections 12 using the protective sections 14 as the etching mask, thus forming the reflective sections 12.

[0033] As described above, the optical element 10 comprises the upper transparent plastic layer 15, which covers the reflective sections 12. The upper transparent plastic layer 15 protects the transmission diffraction section 20 from friction and moisture.

[0034] The upper transparent plastic layer 15 comprises a back surface 15r that faces the lower transparent plastic layer 11. The back surface 15r includes protrusions 15a and depressions 15b arranged alternately along the Y-axis. In this description, the protrusions 15a are the sections that project towards the lower transparent plastic layer 11 along the Z-axis, and the depressions 15b are the sections that project towards the surface of the upper transparent plastic layer 15. A depression 15b and a protrusion 15a that are adjacent to each other along the Y-axis form a reflectance unit section 16. The reflectance unit sections 16 have different lengths along the Y-axis. That is, the back surface 15r of the upper transparent plastic layer 15 has a non-periodic uneven structure formed by the depressions 15b and the protrusions 15a.

[0035] The depressions 15b comprise depressions 15b that differ from each other in the position of their bottom sections on the Z-axis. The elevations 15a comprise elevations 15a that differ from each other in the position of their peak sections on the Z-axis. Each of the depressions 15b and elevations 15a extends along the X-axis in the back surface 15r.

[0036] Each protective section 14 has an uneven structure adapted to the uneven structure of the rear surface section 15r of the upper transparent plastic layer 15 corresponding to the protective section 14. Each reflective section 12 has an uneven structure adapted to the uneven structure of the rear surface section 15r of the upper transparent plastic layer 15 corresponding to the reflective section 12.

[0037] Each protective section 14 has a non-periodic uneven structure equivalent to that of the back surface 15r as described above, and each reflective section 12 has a non-periodic uneven structure equivalent to that of the back surface 15r as described above. As a result, the light incident on the reflective sections 12 through the upper transparent plastic layer 15 is scattered by the reflective sections 12. The reflective sections 12 produce scattered light as reflected light, and the scattered light forms a reflected image. That is, the reflective sections 12 form the reflected image by reproducing the angle of reflection of light reflected by the reflective sections 12, which is different from the angle of light incident on the reflective sections 12.

[0038] The uneven structure of each reflecting section 12 extends substantially along its entire length on the Y-axis. However, it is sufficient that at least a portion of each reflecting section 12 exhibits the uneven structure on the Y-axis.

[0039] Fig. Figure 3 shows a cross-sectional shape of the optical element 10 in a ZX plane. As described above, the depressions 15b formed on the back surface 15r include depressions 15b that differ from each other in the position of their bottom sections on the Z-axis. The protrusions 15a include protrusions 15a that differ from each other in the position of their tip sections on the Z-axis. Therefore, if a protective section 14 and a reflective section 12, which are layered, form a laminate structure, a multitude of laminate structures can exist that differ from each other in their position on the Z-axis. Furthermore, the laminate structures can include laminate structures that are identical in a position on the Z-axis.

[0040] As in Fig. As shown in Figure 4, the reflecting sections 12 and the transmitting sections 13 are arranged at equal intervals along the X-axis. A reflecting section 12 and a transmitting section 13 adjacent to each other along the X-axis form a transmitting period section 17. The width of the transmitting period section 17 along the X-axis is one lattice period d.

[0041] If the grating period d is greater than 0.20 µm and less than or equal to 20 µm, the transmission diffraction section 20 forms a multitude of diffraction patterns with diffracted light produced by diffracting the light transmitted through the transmitting sections 13 in a predetermined direction, and the diffraction patterns differ from one another in color. To form vivid or illustrative diffraction patterns by the transmission diffraction section 20, the grating period d is preferably 0.35 µm or greater. To achieve a desirable viewing angle of the diffraction patterns, i.e., the angle of dispersion or scattering of the diffraction patterns, for the purpose of visual recognition of the patterns by an observer, the grating period d is preferably between 0.5 µm and 10 µm inclusive. A grating period d of more than 20 µm reduces the viewing angle of the diffraction patterns and narrows the range of angles at which the observer can perceive the images.

[0042] If a transmitting diffraction grating has a grating period d that is smaller than the wavelength of light in the visible light range, such a diffraction grating is called a subwavelength grating. The subwavelength grating absorbs wavelengths in a specific range, reflects wavelengths in a specific range, and separates polarized light from the incident light. For the subwavelength grating to separate polarized light from light in the visible light range, for example, light from 400 to 700 nm, the grating period d of the subwavelength grating preferably has a length of 0.15 µm or more and less than 0.35 µm, which is less than half the length of the wavelength of visible light. More preferably, the grating period d is between 0.15 µm and 0.3 µm inclusive.

[0043] If the grating period d is greater than 0.20 µm and less than 0.35 µm, the transmission diffraction section 20 diffracts visible light and transmits only the polarized light, which is the component perpendicular to the reflecting sections 12. Operation of the optical element

[0044] Referring to Fig. 5 and Fig. Section 6 below describes the operation of the optical element.

[0045] As in Fig. As shown in Figure 5, when light falls on the reflective sections 12 of the optical element 10 through the upper transparent plastic layer 15, the reflective sections 12, each of which has a non-periodic uneven structure, reflect the incident light Li in different directions. In other words, the reflected light Lr produced by the reflective sections 12 is scattered light. If the incident light Li is white visible light, the optical element 10 reflects white scattered light.

[0046] As in Fig. As shown in Figure 6, when light strikes the reflecting sections 12 of the optical element 10 through the upper transparent plastic layer 15, the incident light Li passes through the transmitting sections 13 and emits from the rear surface of the lower transparent plastic layer 11, which faces surface 11s, as transmitted light Lt. Here, the transmission diffraction section 20 diffractes light rays of different wavelengths in the incident light Li at transmission angles that vary depending on the light ray, forming diffraction patterns that differ from each other in color.

[0047] Consequently, when observing reflected light, with an observer positioned above the optical element 10 opposite the upper transparent plastic layer 15 of the optical element 15, the observer observes white scattered light, which is scattered by the reflecting sections 12. In contrast, when observing transmitted light, with an observer positioned above the optical element 10 opposite the lower transparent plastic layer 11 of the optical element 10, where light from a light source behind the optical element 10 is transmitted through the optical element 10, the observer observes iridescent (shimmering, iridescent) diffracted light, which is diffracted by the transmission diffraction section 20. Method for manufacturing the optical element

[0048] Referring to Fig. The procedure for manufacturing the optical element is described below in sections 7 to 10.

[0049] The fabrication of the optical element 10 begins with the formation of an original plate of the upper transparent plastic layer 15, which has non-periodic uneven structures. The original plate is formed by photolithography using an electron beam lithography system. In the sections of the original plate that correspond to the sections of the upper transparent plastic layer 15 in which the reflective sections 12 are located, a non-periodic uneven structure is formed, which has a smaller specific surface area, i.e., a lower aspect ratio. In the sections of the original plate that correspond to the sections of the upper transparent plastic layer 15 in which the reflective sections 12 are not located, an uneven structure is formed, which has a larger specific surface area, i.e., a higher aspect ratio.Aspect ratio, as the non-periodic uneven structure for scattering light.

[0050] As in Fig. As shown in Figure 7, the uneven structure on the surface of the original plate is replicated to form the upper transparent plastic layer 15, which exhibits the non-periodic uneven structure. The upper transparent plastic layer 15 can be formed, for example, using a photopolymer process. That is, to form the upper transparent plastic layer 15, an ultraviolet curing resin is applied to the original plate and then irradiated with ultraviolet rays to cure it. The cured ultraviolet curing resin is then peeled off, forming the upper transparent plastic layer 15 with the non-periodic uneven structure.

[0051] The method for forming the upper transparent plastic layer 15 is not limited to the photopolymer process described above and can be another process such as heat stamping, hot / cold printing, a photopolymer process, and a nanoprinting process.

[0052] As in Fig. As shown in Figure 8, a metal film, such as an aluminum film 12M, is vacuum-deposited (vacuum-deposited) onto the entire surface of the upper transparent plastic layer 15, which has an uneven structure. On the surface of the upper transparent plastic layer 15 with the uneven structure, the section with the lower aspect ratio is covered by the aluminum film 12M of a predetermined thickness, while the section with the higher aspect ratio receives only a small amount of aluminum film 12M. Furthermore, in the section of the upper transparent plastic layer 15 with the higher aspect ratio, the aluminum film 12M is formed linearly along a given axis or in an island-like pattern on the surface of the upper transparent plastic layer 15.

[0053] The dry coating process for forming the aluminium film 12M is not limited to vacuum deposition, and any of the dry coating processes listed above can be used.

[0054] As in Fig. As shown in Figure 9, magnesium fluoride is vacuum-deposited onto the entire surface of the aluminum film 12M to protect it. As with the aluminum film 12M, the section of the upper transparent plastic layer 15 with the lower aspect ratio is covered by a magnesium fluoride film 14M to form the protective sections 14, whereas the magnesium fluoride film 14M is sparse in the section with the higher aspect ratio. Furthermore, in the section of the upper transparent plastic layer 15 with the higher aspect ratio, the magnesium fluoride film 14M is formed linearly along a given axis or as islands on the surface of the upper transparent plastic layer 15.

[0055] The dry coating process for forming the magnesium fluoride film 14M is not limited to vacuum deposition, and any of the dry coating processes listed above can be used.

[0056] The aluminum film 12M dissolves in an alkaline solution, allowing etching to be performed using the alkaline solution. In contrast, the magnesium fluoride film 14M does not dissolve in the alkaline solution. Therefore, the magnesium fluoride film 14M can serve as a mask when wet etching of the aluminum film 12M is performed using the alkaline solution.

[0057] Referring to Fig. In step 10, the upper transparent plastic layer 15, on which the aluminum film 12M and the magnesium fluoride film 14M are formed, is immersed in the alkaline solution. Consequently, in the linear or islanded laminate structure of the aluminum film 12M and magnesium fluoride film 14M, the aluminum film 12M is brought into contact with the alkaline solution and is therefore alkaline etched. When the upper transparent plastic layer 15, which has the lower aspect ratio, is sectioned, the aluminum film 12M is protected by the magnesium fluoride film 14M. Therefore, the aluminum film 12M is not etched in the etching process using the alkaline solution.

[0058] This manufacturing process allows the magnesium fluoride film 14M to etch only the section of aluminum film 12M corresponding to the reflective sections 12, without the need to form the magnesium fluoride film 14M into a pattern to protect the aluminum film 12M. Accordingly, such a manufacturing process allows high-resolution reflective sections 12 to be formed in desired positions by adjusting the aspect ratios of the uneven structures on the surface of the original plate used to form the upper transparent plastic layer 15.

[0059] In the manufacturing process described above, the thickness of the magnesium fluoride film 14M forming the protective sections 14, i.e., the thickness along the Z-axis, is preferably not more than half the thickness of the aluminum film 12M forming the reflective sections 12. For example, if the thickness of the aluminum film 12M is between 5 nm and 500 nm inclusive, the thickness of the magnesium fluoride film 14M is preferably between 0.3 nm and 200 nm inclusive and not more than half the thickness of the aluminum film 12M.

[0060] When the surface of the upper transparent plastic layer 15 is sectioned to remove the aluminum film 12M (i.e., the section including the transmitting sections 13 of the optical element 10), a significantly thin magnesium fluoride film 14M is formed on the aluminum film 12M. When the surface of the upper transparent plastic layer 15 is sectioned to retain the aluminum film 12M (i.e., the section corresponding to the reflective sections 12 of the optical element 10), a magnesium fluoride film 14M is formed to an extent suitable for protecting the aluminum film 12M corresponding to the reflective sections 12 from dissolution or a change in its properties.

[0061] The following advantages are achieved by adjusting the material and thickness of the thin film for forming the reflective sections 12 and the material and thickness of the thin film for forming the protective sections 14 as described above. The difference between the etching rate of the metal film for forming the reflective sections 12 in the section of the upper transparent plastic layer 15 corresponding to the reflective sections 12 and the etching rate in the section comprising the transmitting sections 13, which does not correspond to the reflective sections 12, can be increased. This promotes etching of the section to be etched and increases the yield of the optical element 10. Furthermore, the section not to be etched is more likely to retain its predetermined shape and properties, thereby stabilizing the quality of the optical element 10.

[0062] In other words, the thickness of the aluminium film 12M and the thickness of the magnesium fluoride film 14M, as described above, are suitable for etching the aluminium film 12M, which is formed in the region of the larger specific surface area.

[0063] After the reflective sections 12 and the protective sections 14 have been formed, an ultraviolet curing resin is applied to the back surface 15r of the upper transparent plastic layer 15 and cured. This forms a lower transparent plastic layer 11 that covers the reflective sections 12 and the protective sections 14. The step of forming the lower transparent plastic layer 11 can be omitted.

[0064] The advantages of the optical element of the first embodiment are now described. (1) A single optical element 10 provides diffraction patterns formed by the transmitted light Lt, which differ from each other in color, in addition to a reflection pattern formed by the reflected light Lr. Therefore, additional optical effects are added to the single optical element 10. (2) The light reflected by the optical element 10 is scattered light, which is scattered by the uneven structure, and the light transmitted by the optical element 10 is diffracted light, which is produced by the transmission diffraction section 20. This illustrates the difference between the light reflected by the optical element 10 and the light transmitted by the optical element 10. (3) If the grating period d of the transfer period section 17 is greater than 0.20 µm and less than 0.35 µm, the transfer diffraction section 20 diffracts visible light and transmits only the polarized light which is the component perpendicular to the reflecting sections 12 in the visible light incident on the transfer diffraction section 20. (4) If the grating period d at the transmission period section 17 is between 0.35 µm and 20 µm inclusive, the visible light incident on the transmission diffraction section 20 will be diffracted more reliably. Variations of the first embodiment

[0065] The first embodiment described above can be modified as follows. Fig. For the sake of simplicity in explaining the reflective sections 12, the upper transparent plastic layer 15 is not shown in Figures 13 to 17 below.

[0066] Each reflective section 12 can be shaped like a strip extending along the X-axis instead of the Y-axis. In such a structure, the reflective sections 12 are arranged at equal intervals along the Y-axis, and the Y-axis serves as an example of a given axis. Alternatively, each reflective section 12 can be shaped like a strip extending along an axis of extension that intersects the Y-axis at a predetermined angle other than a right angle. In such a structure, the reflective sections 12 are arranged at equal intervals along the axis perpendicular to the axis of extension, and the axis perpendicular to the axis of extension serves as an example of a given axis.

[0067] The depressions and protrusions on the back surface 15r of the upper transparent plastic layer 15 need not extend along the X-axis and may have the shape described below. That is, each of the depressions and protrusions may extend along an axis that intersects the Y-axis at a predetermined angle other than a right angle.

[0068] For example, as in Fig. As shown in Figure 11, the depressions 15b extend along the axis that forms an angle of 45° with the Y-axis. In this structure, each elevation 15a that is clamped (or supported) by two corresponding depressions 15b adjacent to each other along the X-axis also extends along the axis that forms an angle of 45° with the Y-axis. Fig. Figure 11 shows, for the sake of simplicity in explaining the uneven structure of the back surface 15r of the upper transparent plastic layer 15, the upper transparent plastic layer 15 inverted on the Z-axis from the position shown in Fig. 2 is shown.

[0069] The structure, including the reflective sections 12 formed on such an upper transparent plastic layer 15, produces, as reflected light Lr, scattered light with a directionality along the longitudinal axis of the protrusions 15a, i.e., the axis forming an angle of 45° with the Y-axis. Therefore, in the optical element 10, including the upper transparent plastic layer 15, which has the rear surface 15r where depressions 15b and protrusions 15a extend along a predetermined axis, the reflective sections 12 produce, as reflected light, scattered light with a directionality along a predetermined axis.

[0070] As in Fig. As shown in Figure 12, the depressions 15b in the back surface 15r of the upper transparent plastic layer 15 can extend along different axes, and the protrusions 15a can likewise extend along different axes. Unlike the optical element 10, including the upper transparent plastic layer 15, which is shown in Fig. As shown in 11, the optical element 10, including the upper transparent plastic layer 15, which is in Fig. Figure 12 shows isotropically scattered light from incident light Li and reflected light Lr, which has no predetermined directionality. Fig. Figure 12 shows, for the sake of simplicity in explaining the uneven structure of the back surface 15r of the upper transparent plastic layer 15, the upper transparent plastic layer 15 emitted along the Z-axis, from which in Fig. Position 2 shown.

[0071] If the upper transparent plastic layer 15 of the optical element 10 includes the section with the uneven structure that produces scattered light with a directionality and the section with the uneven structure that scatters the incident light isotropically, the optical element 10 provides more complex optical effects.

[0072] Instead of arranging the depressions and ridges in each reflective section 12 consecutively and alternately only along the Y-axis, the depressions and ridges in each reflective section 12 can be arranged consecutively and alternately along both the X- and Y-axes.

[0073] As in Fig. As shown in Figure 13, the reflective sections 12 can have different lengths along the y-axis. For example, the lengths along the y-axis of the reflective sections 12 can gradually decrease from the reflective section 12 located at one end on the x-axis towards the reflective section 12 located at the other end. Alternatively, the reflective sections 12 can comprise reflective sections 12 of different lengths along the y-axis, and the reflective sections 12 can be arranged along the x-axis without any predetermined regularity in length along the y-axis.

[0074] As in Fig. As shown in Figure 14, a single metal film can be formed over the entire surface of the lower transparent plastic layer 11, i.e., over the entire back surface 15r of the upper transparent plastic layer 15, and transmitting sections 13 can be defined by the metal film.

[0075] In this structure, the transmitting sections 13 can be arranged at equal intervals along the X-axis, and each transmitting section 13 can extend along the Y-axis. Alternatively, the transmitting sections 13 can be arranged at equal intervals along the Y-axis, and each transmitting section 13 can extend along the X-axis. Furthermore, each transmitting section 13 can extend along an extension axis that forms a predetermined angle with the Y-axis, and the transmitting sections 13 can be arranged at equal intervals along the axis perpendicular to the extension axis.

[0076] In this structure, the sections that are clamped by the respective transmitting sections 13 act as reflective sections 12a, and the section that surrounds the transmitting sections 13 also acts as a reflective section 12b.

[0077] As in Fig. As shown in 15, the optical element 10, which is in Fig. Figure 14 shows that the transferring sections 13 can be modified such that they have different lengths along the Y-axis. For example, the lengths along the Y-axis of the transferring sections 13 can gradually decrease from the transferring section 13 located at one end on the X-axis towards the transferring section 13 located at the other end. Alternatively, the transferring sections 13 can be of different lengths along the Y-axis, and the transferring sections 13 can be arranged at the X-axis without a predetermined regularity in length along the Y-axis.

[0078] As in Fig. As shown in Figure 16, the optical element 10 can comprise a plurality of rectangular reflecting sections 12, and the reflecting sections 12 can be arranged at equal intervals along the X-axis and also at equal intervals along the Y-axis. This structure includes transfer sections 13, each of which extends along the Y-axis and is arranged between corresponding two reflecting sections 12 that are adjacent to each other along the X-axis. The transfer sections 13 extending along the Y-axis are perpendicular to the transfer sections 13 extending along the X-axis.

[0079] A reflecting section 12 and a transmitting section 13, adjacent to each other along the X-axis, form a first diffraction period section 21. The width of the first diffraction period section 21 along the X-axis is a first grating period d1. A reflecting section 12 and a transmitting section 13, adjacent to each other along the Y-axis, form a second diffraction period section 22. The width of the second diffraction period section 22 along the Y-axis is a second grating period d2. The first grating period d1 can be equal to the second grating period d2. However, the first grating period d1 can differ from the second grating period d2.

[0080] The in Fig. The optical element 10 shown in Figure 16 has a so-called cross-grating structure. When viewing the transmitted light from such an optical element 10 using a bar-shaped or rod-shaped light source such as a fluorescent lamp, the light transmitted through the optical element 10 radiates as shimmering diffraction light when the rod-shaped light source extends parallel to the X-axis or when the rod-shaped light source extends parallel to the Y-axis.

[0081] The reflective sections 12 can be arranged along the Y-axis and along an axis that intersects the X-axis at a predetermined angle. Alternatively, the reflective sections 12 can be arranged along the X-axis and along an axis that intersects the Y-axis at a predetermined angle. Furthermore, if an axis along which reflective sections 12 and transmitting sections 13 are arranged consecutively is a periodicity axis, the optical element 10 can have reflective sections 12 and transmitting sections 13 arranged along three or more different periodic axes.

[0082] As in Fig. As shown in Figure 17, in the optical element 10 a single metal film can be formed over the entire surface of the lower transparent plastic layer 11, i.e. over the entire rear surface 15r of the upper transparent plastic layer 15, and transmitting sections 13 can be defined by the metal film.

[0083] In this structure, the transmitting sections 13 are arranged at equal intervals along the X-axis and equal intervals along the Y-axis. This structure includes reflective sections 12a, each extending along the Y-axis and positioned between corresponding pairs of transmitting sections 13 that are adjacent to each other along the X-axis. The reflective sections 12a extending along the Y-axis are perpendicular to the reflective sections 12a extending along the X-axis. Furthermore, the section of metal film surrounding the transmitting sections 13 also serves as a reflective section 12b.

[0084] A reflecting section 12a and a transmitting section 13, adjacent to each other along the X-axis, form a first diffraction period section 21. The width of the first diffraction period section 21 along the X-axis is a first grating period d1. A reflecting section 12a and a transmitting section 13, adjacent to each other along the Y-axis, form a second diffraction period section 22. The width of the second diffraction period section 22 along the Y-axis is a second grating period d2. The first grating period d1 can be equal to the second grating period d2. However, the first grating period d1 can be different from the second grating period d2.

[0085] As in the case of optical element 10, which is in Fig. As shown in 16, the optical element 10, which is located in Fig. As shown in 17, a so-called cross-lattice structure is formed. When the reflecting sections 12a of the in Fig. The optical element 10 shown in Figure 17 is located at the same positions as the transmitting sections 13 of the [document / section]. Fig. The optical element 10 shown in 16 is arranged and the transmitting sections 13 of the in Fig. The optical element 10 shown in 17 is located at the same positions as the reflecting sections 12 of the [document / model]. Fig. The optical element 10 shown in 16 is arranged in the optical element 10 shown. Fig. 17 the same optical effect as optical element 10 of the Fig. 16 up.

[0086] The transmitting sections 13 can be arranged along the Y-axis and along an axis that intersects the X-axis at a predetermined angle. Alternatively, the transmitting sections 13 can be arranged along the X-axis and along an axis that intersects the Y-axis at a predetermined angle. Furthermore, if an axis along which reflecting sections 12 and transmitting sections 13 are arranged consecutively is a periodicity axis, the optical element 10 can comprise reflecting sections and transmitting sections 13 arranged along three or more different periodicity axes.

[0087] As described above, this can be done in Fig. The optical element 10 shown in 17 is structured in such a way as to produce the same optical effect as the one shown in Fig. The optical element 10 shown in 16 is therefore possible. A selection can be made between the one shown in Fig. 17 shown optical element 10 and the one in Fig. The optical element shown in 16 is dependent on the ease of forming reflective sections.

[0088] The optical element 10 need not have the protective sections 14. The optical element 10, which does not have the protective sections 14, can be manufactured by the following method.

[0089] In the same manner as the manufacturing process described above, the manufacturing process of the optical element 10 begins with the formation of an original plate of the upper transparent plastic layer 15 with a non-periodic uneven structure. To form the original plate, for example, a SUS plate is sandblasted to create a non-periodic uneven structure on its surface. This forms the original plate with a non-periodic uneven surface structure. Alternatively, the original plate can be formed by creating a photoresist film with a non-periodic uneven surface structure using photolithography with a laser or electron beam lithography system or an exposure system. This forms the original plate with non-periodic uneven surface structures.After a conductive film is applied to the trained original plate using a dry coating process, actual products can be trained through electrical training.

[0090] As in Fig. As shown in Figure 18, a replication of the uneven structure in the surface of the original plate forms the upper transparent plastic layer 15 with the non-periodic uneven structure. The upper transparent plastic layer 15 can be formed, for example, by a photopolymer process.

[0091] The method for forming the upper transparent plastic layer 15 is not limited to the photopolymer process described above and may be another process such as heat stamping, hot / cold printing, a photopolymer process, and a nanoprinting process.

[0092] As in Fig. As shown in Figure 19, the entire surface of the upper transparent plastic layer 15, which has the non-periodic uneven structure, is covered or coated with a metal film to form reflective sections 12, which can be an aluminum film 12M, by means of a dry coating process. The dry coating process for forming the aluminum film 12M can be any of the dry coating processes listed above.

[0093] As in Fig. As shown in 20, a photoresist PR is then applied to the entire surface of the aluminium film 12M.

[0094] As in Fig. As shown in Figure 21, the photoresist PR is exposed to a pattern of laser light such that the photoresist PR is cured in the sections of the aluminum film 12M corresponding to reflective sections 12. This forms a mask that is used to etch the aluminum film 12M. The section of the photoresist that is not cured and the section of the aluminum film 12M that is not covered by the mask are alkaline etched, thereby forming reflective sections 12.

[0095] This manufacturing process can also be used to produce an optical element 10 including protective sections 14. To form an optical element 10 including protective sections 14, a thin film for forming protective sections 14, which can be a magnesium fluoride film, is formed before the application of the photoresist PR. Then, the magnesium fluoride film is etched after the photoresist PR has been developed and before an alkaline etching of the aluminum film 12M.

[0096] The optical element 10 can be produced by a process different from the one described above, such as a "washing-see-light" treatment or a process that physically removes the metal film. In the "washing-see-light" treatment, a water-soluble resin is applied to the section of the upper transparent plastic layer 15 corresponding to the transferred sections 13, and then a metal film is formed to create reflective sections 12 by a dry coating process. The upper transparent plastic layer 15, on which the water-soluble resin and the metal film are formed, is then washed with water, thereby removing the water-soluble resin and the metal film formed on the water-soluble resin.

[0097] The process that physically removes the metal film physically removes the section of the metal layer corresponding to the transmitted sections 13 by directing laser light in a pattern.

[0098] After the reflective sections 12 have been formed, an ultraviolet curable resin, for example, is applied to the back surface 15r of the upper transparent plastic layer 15 and cured. This forms the lower transparent plastic layer 11, which covers the reflective sections 12 and the protective sections 14. However, the lower transparent plastic layer 11 can be omitted.

[0099] As described above, in the method for manufacturing an optical element 10 without protective sections 14, the reflective sections 12 can be formed on the lower transparent plastic layer 11 instead of on the upper transparent plastic layer 15. In this case, the upper transparent plastic layer 15 can be omitted. Second embodiment

[0100] Referring to Fig. In sections 22 to 27, an optical element according to a second embodiment is described below. The optical element of the second embodiment is the same as the optical element of the first embodiment in that the reflective sections scatter the incident light, but differs from the first embodiment in the structure of the reflective sections for scattering the incident light. Therefore, the following descriptions will focus on this difference. The same reference numerals are given to those components that are the same as the corresponding components of the optical element of the first embodiment. Such components are not described in detail. In the following descriptions, the structure of the optical element and the operation of the optical element are described in that order. Structure of the optical element

[0101] Referring to Fig. The structure of the optical element is described below in sections 22 to 25. Fig. 22 and Fig. Figure 25 does not show the upper transparent plastic layer for the sake of simplicity in explaining the structure of the optical element. Fig. 22 and Fig. 25 are shaded with dots to indicate the positions of the reflective sections relative to the lower transparent plastic layer. Furthermore, the uneven structure formed on the surface of the lower transparent plastic layer is shown in Fig. 22 not shown for illustrative purposes.

[0102] As in Fig. As shown in Figure 22, an optical element 10 comprises a plurality of reflective sections 31 formed over a surface 11s of the lower transparent plastic layer 11. Each reflective section 31 is shaped like a strip extending along the Y-axis. The reflective sections 31 are arranged at equal intervals along the X-axis, which is an example of a first axis. Each reflective section 31 has a semi-cylindrical surface projecting from the surface 11s. The semi-cylindrical surface of each reflective section 31 extends along its entire length along the Y-axis. However, it is sufficient that at least a portion of each reflective section 31 has the semi-cylindrical surface along the Y-axis. The Y-axis is an example of a second axis.The semi-cylindrical surface of each reflecting section 31 extends along its entire length on the X-axis. However, it is sufficient that at least a part of each reflecting section 31 has the semi-cylindrical surface on the X-axis.

[0103] As in Fig. As shown in Figure 23, since each reflective section 31 has a semi-cylindrical surface, the position of the reflective section 31 on the Z-axis does not change over its entire extent along the Y-axis as seen in a cross-section taken along a ZY-plane. Furthermore, since each protective section 32 has a semi-cylindrical surface, the position of the protective section 32 on the Z-axis does not change over its entire extent along the Y-axis as seen in a cross-section taken along a ZY-plane.

[0104] As in Fig. As shown in Figure 24, the surface of the upper transparent plastic layer 15, which is in contact with the lower transparent plastic layer 11, is a back surface 15r. The back surface 15r of the upper transparent plastic layer 15 comprises depressions 15b arranged at equal intervals along the X-axis. Each depression 15b is defined by a cylindrical surface extending along the Y-axis.

[0105] Each reflective section 31 is configured in accordance with a corresponding recess 15b such that the reflective section 31 has a semi-cylindrical surface that matches the shape of the recess 15b. Each protective section 32 is configured in the same way as the reflective section 31 in accordance with a corresponding recess 15b such that the protective section 32 has a semi-cylindrical surface that matches the shape of the recess 15b.

[0106] As in Fig. As shown in Figure 25, a reflective section 31 and a transmitting section 13, which are adjacent to each other along the X-axis, form a transmission period section 33. The lattice period d of the transmission period section 33 is preferably larger than 0.20 µm and 20 µm or smaller, as in the case with the lattice period d in the first embodiment. Operation of the optical element

[0107] Referring to Fig. 26 and Fig. 27 The operation of the optical element is described below.

[0108] As in Fig. As shown in Figure 26, when light falls on the reflective sections 31 of the optical element 10 through the upper transparent plastic layer 15, the reflective sections 31, each of which is shaped as a convex projection towards the upper transparent plastic layer 15, reflect the incident light Li in directions depending on the sections of the reflective sections 31 onto which the incident light Li falls. In other words, each reflective section 12 produces scattered light as reflected light Lr. If the incident light Li is white visible light, the optical element 10 reflects white scattered light.

[0109] As in Fig. As shown in Figure 27, when light enters the optical element 10 through the upper transparent plastic layer 15 and strikes the reflecting sections 31, the incident light Li passes through the transmitting sections 13 and is emitted from the rear surface of the lower transparent plastic layer 11, which faces surface 11s, as transmitted light Lt. The transmitting diffraction section 20 diffractes the light rays of different wavelengths in the incident light Li at angles that vary depending on the light ray, forming diffraction patterns that differ from each other in color.

[0110] Accordingly, when observing reflected light, the observer of optical element 10 observes white scattered light, which is scattered by the reflecting sections 12. When observing scattered light, the observer observes shimmering diffracted light, which is diffracted by the transmission diffraction section 20.

[0111] One advantage of the optical element of the second embodiment will now be described.

[0112] (5) The light reflected by the optical element 10 is scattered light, which has been scattered by the semi-cylindrical surfaces, and the light transmitted by the optical element 10 is diffracted light, which has been diffracted by the transmission diffraction section 20. This illustrates the difference between the light reflected by the optical element 10 and the light transmitted by the optical element 10. Variation of the second embodiment

[0113] The second embodiment described above can be modified as follows.

[0114] Each of the reflective sections 21 can be shaped like a strip extending along the X-axis instead of the Y-axis. In such a structure, the reflective sections 31 are arranged at equal intervals along the Y-axis. Alternatively, each reflective section 31 can be shaped like a strip extending along an axis of extension that intersects the Y-axis at a predetermined angle other than a right angle. In such a structure, the reflective sections 31 are arranged at equal intervals along the axis perpendicular to the axis of extension.

[0115] The reflective sections 31 can have different lengths along the Y-axis. For example, the lengths along the Y-axis of the reflective sections 31 can gradually decrease from the reflective section 31 located at one end on the X-axis towards the reflective section 31 located at the other end. Alternatively, the reflective sections 31 can have different lengths along the Y-axis, and the reflective sections 31 can be arranged along the X-axis without a predetermined regularity in length along the Y-axis. That is, the modification of the first embodiment, as in Fig. As shown in 13, it can be combined with the reflective sections 31 of the second embodiment.

[0116] In the optical element 10, a single metal film can be formed over the entire surface of the lower transparent plastic layer 11, i.e., over the entire back surface 15r of the upper transparent plastic layer 15, and the transmitting sections 13 can be defined by the metal film. That is, the modification of the first embodiment as in Fig. The second embodiment shown in 14 can be combined with the reflective sections 31.

[0117] In the optical element 10, a single metal film can be formed over the entire surface of the lower transparent plastic layer 11, i.e., the entire back surface 15r of the upper transparent plastic layer 15, and the transmitting sections 13 can be defined by the metal film. Furthermore, the transmitting sections 13 can have transmitting sections 13 of different lengths along the Y-axis. That is, the modification of the first embodiment as in Fig. The 15 shown can be combined with the reflective sections 31 of the second embodiment.

[0118] The optical element 10 can have a cross-grating structure. That is, the modification of the first embodiment as in Fig. Figure 16 can be combined with the reflective sections 31 of the second embodiment. Furthermore, the modification of the first embodiment can be carried out as shown in Fig. 17 shown combined with the reflective sections 31 of the second embodiment. Third example

[0119] Referring to Fig. In sections 28 to 33, an optical element according to a third embodiment is described below. The optical element of the third embodiment differs from the optical element of the first embodiment in the structure of the reflecting sections and the optical effect achieved by these reflecting sections. Therefore, the following descriptions will focus on this difference. The same reference numerals are given to components that are identical to the corresponding components of the optical element of the first embodiment. Such components are not described in detail. In the following descriptions, the structure of the optical element and its operation are described in that order. Structure of the optical element

[0120] Referring to Fig. The structure of the optical element is now described in sections 28 to 31. Fig. 28 and Fig. Figure 31 does not show the upper transparent plastic layer for the sake of simplicity in describing or explaining the structure of the optical element. Fig. 28 and Fig. Figure 31 shows that, to illustrate the position of the reflective sections relative to the lower transparent plastic layer, the reflective sections are shaded with dots. Furthermore, the uneven structure formed in the surface of the lower transparent plastic layer is shown in Fig. 28 not shown for illustrative purposes.

[0121] As in Fig. As shown in Figure 28, the optical element 10 comprises a plurality of reflective sections 41 formed over the surface 11s of the lower transparent plastic layer 11. Each of the reflective sections 11 is shaped like a strip extending along the Y-axis. The reflective sections 41 are arranged at equal intervals along the X-axis.

[0122] As in Fig. As shown in Figure 29, the back surface 15r of the upper transparent plastic layer 15 comprises protrusions 15a arranged at equal intervals along the Y-axis. Each protrusion 15a is a ridge extending along the X-axis and having a rectangular cross-sectional shape along the ZY-axes. The protrusions 15a are identical to the projection extent along the Z-axis towards the back surface 11r of the lower transparent plastic layer 11.

[0123] Each reflective section 41 is shaped like a strip extending along the Y-axis on the back surface 15r of the upper transparent plastic layer 15. Therefore, each reflective section 41 has a structure that corresponds to the section of the back surface 15r of the upper transparent plastic layer 15 where the reflective section 41 is located. That is, each reflective section 41 comprises a plurality of depressions 41a extending towards the back surface 11r of the lower transparent plastic layer 11, and a plurality of protrusions 41b that are further away from the back surface 11r of the lower transparent plastic layer 11 than the depressions 41a along the Z-axis.

[0124] In each reflecting section 41, the depressions 41a and the protrusions 41b are arranged consecutively and alternately along the Y-axis. The axis along which the depressions 41a and the protrusions 41b are arranged consecutively and alternately is a periodicity axis. That is, the reflecting section 41 has an uneven structure that is periodic along the Y-axis. In a reflecting section 41, a depression 41a and a protrusion 41b that are adjacent to each other along the Y-axis form a reflection period section 43. The width of the reflection period section 43 along the Y-axis is one lattice period dr. The depressions 41a and the protrusions 41b are arranged consecutively and alternately over the entire extent along the Y-axis of the reflecting section 41.However, it is sufficient that depressions 41a and elevations 41b are arranged consecutively and alternately over a part of the Y-axis.

[0125] If the grating period dr is between 0.15 µm and 20 µm inclusive, the reflecting sections 41 form a multitude of diffraction patterns with diffracted light diffracted by the reflection period sections 43, and the diffraction patterns differ from each other in color. That is, the reflecting sections 41 form reflection patterns by reproducing the reflection angle of the light reflected by the reflecting sections 41, which is different from the angle of the incident light on the reflecting sections 41.

[0126] The grating period dr is preferably between 0.5 µm and 10 µm inclusive. When the grating period dr is between 0.5 µm and 10 µm inclusive, the viewing angle of the diffraction pattern is increased compared to the case when the grating period dr lies outside this range.

[0127] If the grating period dr is smaller than the wavelength of light in the visible light range, the reflecting sections 41 form a subwavelength grating, and the reflecting sections 41 can separate polarized light from the incident light. For the subwavelength grating to separate polarized light from light in the visible light range, for example, light in the range of 400 to 700 nm, the grating period dr preferably has a length of 0.15 µm or more and less than 0.35 µm, which is less than half the length of the wavelengths of visible light. More preferably, the grating period dr is between 0.15 µm and 0.3 µm inclusive.

[0128] If the lattice period dr is greater than 0.20 µm and less than 0.35 µm, the reflecting sections 41 diffract visible light and reflect only the polarized light, which is the component perpendicular to the reflecting sections 41.

[0129] In the same way as the reflective sections 41, each protective section 42 has a structure that corresponds to the section of the back surface 15r of the upper transparent plastic layer 15 where the protective section 42 is located.

[0130] Fig. Figure 30 shows a cross-sectional shape of the optical element 10 in the ZX plane. As described above, the protrusions 15a, formed on the back surface 15r of the upper transparent plastic layer 15, extend along the X-axis. The protrusions 15a are identical in their extent along the Z-axis towards the back surface 11r of the lower transparent plastic layer 11. Therefore, the reflective sections 41 are identical at one position on the Z-axis, and the protective sections 42 are identical at one position on the Z-axis.

[0131] As in Fig. As shown in Figure 31, a reflective section 41 and a transmitting section 13, which are adjacent to each other along the X-axis, form a transmission period section 44. The lattice period dt of the transmission period section 44 is preferably larger than 0.20 µm and 20 µm or less, as in the case with the lattice period d in the first embodiment. Operation of the optical element

[0132] Referring to Fig. 32 and Fig. Section 33 below describes the operation of the optical element.

[0133] As in Fig. Figure 32 shows that when light falls on the reflective sections 41 of the optical element 10 through the upper transparent plastic layer 15, the reflective sections 41, acting as reflective diffraction gratings, reflect the incident light Li. In other words, the reflective sections 41 produce diffracted light as reflected light Lr. If the incident light Li is white visible light, the reflective sections 41 produce shimmering diffracted light as reflected light Lr.

[0134] As in Fig. As shown in Figure 33, when light enters the optical element 10 through the upper transparent plastic layer 15 and strikes the reflecting sections 41, the incident light Li passes through the transmitting sections 13 and is emitted from the rear surface 11r of the lower transparent plastic layer 11, which faces the surface 11s, as transmitted light Lt. The transmission diffraction section 20 diffractes the light rays of different wavelengths in the incident light Li at angles that vary depending on the light ray, forming diffraction patterns that differ from each other in color.

[0135] Accordingly, when observing reflected light, the observer of optical element 10 observes shimmering diffracted light that is reflected by the reflecting sections 41. When observing transmitted light, the observer observes shimmering diffracted light that is diffracted by the transmission diffraction section 20.

[0136] The diffracted light diffracted by the reflecting sections 41 may be the same as or different from the diffracted light diffracted by the transmission diffraction section 20.

[0137] The advantages of the optical element of the third embodiment will now be described.

[0138] (6) Both the light reflected by the optical element 10 and the light transmitted by the optical element 10 are diffracted light. Therefore, in order to produce the optical effects of the optical element 10, the diffraction state of the diffracted light resulting from transmission and the diffraction state of the diffracted light resulting from reflection must both be the same as those of the optical element 10. This increases the difficulty of reproducing the optical element 10.

[0139] (7) If the grating period dr of the reflection period sections 43 is greater than 0.20 µm and less than 0.35 µm, the reflection period sections 43 diffract visible light and transmit only the polarized light which is the component perpendicular to the reflecting sections 41 in the visible light incident on the reflecting sections 41.

[0140] (8) If the grating period dr of the reflection period sections 43 is between 0.35 µm and 20 µm inclusive, the visible light incident on the reflecting sections 41 will be diffracted more reliably. Variations of the third embodiment

[0141] The third embodiment described above can be modified as follows.

[0142] Each reflective section 41 can be shaped like a strip extending along the X-axis instead of the Y-axis. In this structure, the reflective sections 41 are arranged at equal intervals along the Y-axis. Alternatively, each reflective section 41 can be shaped like a strip extending along an axis of extension that intersects the Y-axis at a predetermined angle other than a right angle. In this structure, the reflective sections 41 can be arranged at equal intervals along the axis perpendicular to the axis of extension.

[0143] The reflective sections 41 can have different lengths along the Y-axis. For example, the lengths along the Y-axis of the reflective sections 41 can gradually decrease from the reflective section 41 located at one end on the X-axis towards the reflective section 41 located at the other end. Alternatively, the reflective sections 41 can be of different lengths along the Y-axis, and the reflective sections 41 can be arranged along the X-axis without a predetermined regularity of length along the Y-axis. That is, the modification of the first embodiment as in Fig. 13 shown can be combined with the reflective sections 41 of the third embodiment.

[0144] In the optical element 10, a single metal film can be formed over the entire surface of the lower transparent plastic layer 11, i.e., over the entire back surface 15r of the upper transparent plastic layer 15, and the transmitting sections 13 can be defined by the metal film. That is, the modification of the first embodiment as in Fig. The elements shown in Figure 14 can be combined with the reflective sections 41 of the third embodiment.

[0145] In the optical element 10, a single metal film can be formed over the entire surface of the lower transparent plastic layer 11, that is, over the entire back surface 15r of the upper transparent plastic layer 15, and the transmitting sections 13 can be defined by the metal film. Furthermore, the transmitting sections 13 can have transmitting sections 13 of different lengths along the Y-axis. That is, the modification of the first embodiment as in Fig. The third embodiment shown in 15 can be combined with the reflective sections 41.

[0146] The optical element 10 can have a cross-grating structure. That is, the modification of the first embodiment as in Fig. 16 shown, and the reflective sections 41 of the third embodiment can be combined. Furthermore, the modification of the first embodiment can be shown as in Fig. 17 shown, combined with the reflective sections 41 of the third embodiment.

[0147] The depressions 41a and the ridges 41b, which form the reflection period sections 43, are arranged consecutively and alternately along the Y-axis. However, the depressions 41a and the ridges 41b, which form the reflection period sections 43, can be arranged consecutively and alternately along the X-axis and consecutively and alternately along the Y-axis. Alternatively, the depressions 41a and ridges 41b, which form the reflection period sections 43, can be arranged consecutively and alternately along a periodicity axis that intersects the Y-axis at a predetermined angle other than a right angle, and consecutively and alternately along the axis perpendicular to the periodicity axis.

[0148] If the reflection period section 43 is a first periodic section, the optical element 10 can include a second periodic section having an uneven structure that differs in periodicity from the uneven structure of the first periodic section. The second periodic section differs from the first periodic section in at least one grating period and one periodicity axis. The visible light incident on the reflecting section is diffracted by the first periodic section in a direction different from the direction in which the visible light is diffracted by the second periodic section. That is, for the reflecting sections 41, a single reflecting section 41 can include both the first periodic section and the second periodic section.Alternatively, the reflecting sections 41 can include a reflecting section 41 that has only the first periodic section and a reflecting section 41 that has only the second periodic section.

[0149] The structures described above have the following advantage.

[0150] (9) The light reflected by the optical element 10 is a combination of two diffraction beams of different states. This increases the difficulty of reproducing the optical effects. Fourth embodiment

[0151] Referring to Fig. Section 34 below describes an optical element according to a fourth embodiment. The optical element of the fourth embodiment differs from the optical element of the first embodiment in that the single optical element comprises two element sections with different optical effects. Therefore, the following description will focus on this difference. The same reference numerals are given to those components that are identical to the corresponding components of the optical element of the first embodiment. Such components are not described in detail. In the following descriptions, the structure of the optical element and the operation of the optical element are described in that order. Structure of the optical element

[0152] Referring to Fig. Section 34 below describes the structure of the optical element. Fig. Figure 34 shows that for the sake of simplicity in explaining the reflective and transmitting sections of the optical element, the upper transparent plastic layer is not shown, and the reflective sections are shaded or hatched with dots.

[0153] As in Fig. As shown in Figure 34, an optical element 50 comprises a first element section 51 and a second element section 52, which are defined on a lower transparent plastic layer 11. In the same way as the optical element 10 of the first embodiment, the first element section 51 comprises a plurality of reflective sections 12 arranged at equal intervals along the X-axis. Each reflective section 12 is shaped like a strip extending along the Y-axis. Each reflective section 12 has a non-periodic uneven structure. For the first element section 51, the ratio between the sum of the areas of all reflective sections 12 and the sum of the areas of sections that transmit light, including the transmitting sections 13, is a first area ratio S1.The reflecting sections 12 and the transmitting sections 13 are arranged consecutively and alternately along the X-axis. A plurality of reflecting sections 12 and a plurality of transmitting sections 13 form a transmitting diffraction section 20, which has a predetermined grating period da. The axis along which the reflecting sections 12 and the transmitting sections 13 are arranged consecutively and alternately is a periodicity axis. The periodicity axis at the first element section 51 is parallel to the X-axis.

[0154] The second element section 52 comprises a plurality of reflecting sections 61 arranged at equal intervals along the Y-axis. Each reflecting section 61 is shaped like a strip extending along the X-axis. The reflecting section 61 is an example of a scattering section. Each of the transmitting sections 62 is sandwiched between corresponding pairs of reflecting sections 61 that are adjacent to each other along the Y-axis, such that the transmitting sections 62 occupy the space between the reflecting sections 61. In the same way as the reflecting sections 61, the transmitting sections 62 are arranged at equal intervals along the Y-axis. Each transmitting section 62 is shaped like a strip extending along the X-axis. The transmitting section 62 is an example of a second transmitting section.

[0155] As in the case of the reflecting section 12 in the first element section 41, the reflecting section 61 exhibits a non-periodic uneven structure. In the case of the second element section 52, the ratio between the sum of the areas of all reflecting sections 61 and the sum of the areas of sections that transmit light, including the transmitting sections 62, is a second area ratio S2, which may be the same as the first area ratio S1. However, the first area ratio S1 may differ from the second area ratio S2.

[0156] The reflecting sections 61 and the transmitting sections 62 are arranged consecutively and alternately along the Y-axis. A plurality of reflecting sections 61 and a plurality of transmitting sections 62 form a transmission diffraction section 60, which has a predetermined grating period db. The grating period db of the transmission diffraction section 60 at the second element section 52 is equal to the grating period da of the transmission diffraction section 20 at the first element section 51. The axis along which the reflecting sections 61 and the transmitting sections 62 are arranged consecutively and alternately is a periodicity axis. The periodicity axis at the second element section 52 is parallel to the Y-axis. That is, the periodicity axis at the second element section 52 is perpendicular to the periodicity axis at the first element section 51. Operation of the optical element

[0157] In optical element 50, the reflected light from the first element section 51 and the reflected light from the second element section 52 are both scattered light. If the incident light is white visible light, then when viewing the reflected light, white light is observed emitted from the first element section 51 and the second element section 52.

[0158] When considering transmitted light, where a point light source is located on the opposite side of the upper transparent plastic layer 15 from the reflecting sections 12, and the light falls on the optical element 50 along the Z-axis, shimmering diffraction light is observed emitted from the first element section 51 and the second element section 52 within the viewing angles of the element sections.

[0159] In an observation of transmitted light, where a rod-shaped light source extending along the Y-axis, such as a fluorescent lamp, is arranged on the opposite side of the upper transparent plastic layer 15 from the reflective sections 12, and the light is incident on the optical element 50 along the Z-axis, shimmering diffraction light is observed at the first element section 51, whereas diffraction light is not observed at the second element section 52.

[0160] Since the light emitted by the point light source is essentially parallel light, the diffracted light at scattering angles corresponds to wavelengths and is independent of the periodicity axis of the transmission diffraction section. This results in the observation of shimmering diffraction light. In contrast, the rod-shaped light source extends along an axis and provides a larger angle of incidence. Therefore, in the transmission diffraction section with reflecting and transmitting sections extending along an axis that intersects the axis along which the rod-shaped light source extends, diffracted light rays of different wavelengths are combined, and thus shimmering diffraction light is not observed.

[0161] Shimmering diffraction light is observed in the first element section 51, where the transmitting sections 13 extend parallel to the extension axis of the rod-shaped light source, but shimmering diffraction light is not observed in the second element section 52, where the transmitting sections 62 extend perpendicular to the extension axis of the rod-shaped light source.

[0162] When the optical element 50 is rotated 90° about the Z-axis, the transmitting sections 52 in the second element section 52 extend parallel to the axis of extension of the rod-shaped light source, and the transmitting sections 13 in the first element section 51 extend perpendicular to the axis of extension of the rod-shaped light source. Consequently, when transmitting light is observed where light passes through the upper transparent plastic layer 15 along the Z-axis, shimmering diffraction light is observed in the second element section 52, but no shimmering diffraction light is observed in the first element section 51.

[0163] Furthermore, in an observation of transmitted light, where a rod-shaped light source extending along the X-axis is arranged on the opposite side of the upper transparent plastic layer 15 from the reflecting sections, and the light is directed along the Z-axis onto the optical element 50 as in Fig. 34 shows that shimmering diffraction light is observed in the second element section 52, but shimmering diffraction light is not observed in the first element section 41.

[0164] The advantages of the optical element of the fourth embodiment are described below.

[0165] (10) Since the first area ratio S1 is equal to the second area ratio S2, the state of the scattered light from the first element section 51 is more likely to be the same as the state of the scattered light from the second element section 52. Therefore, it is difficult to perceive the boundary between the first element section 51 and the second element section 52 on the side of the optical element 10 where light is reflected. On the other hand, the light transmitted by the first element section 51 differs from the light transmitted by the second element section 52. Therefore, on the side of the optical element 10 where light is reflected, the number of light rays perceived as being contained in the light emitted by the optical element 10 differs from the number perceived on the side of the optical element 10 where light is transmitted.

[0166] (11) The periodicity axis of the transmission diffraction section 20 at the first element section 51 is perpendicular to the periodicity axis of the transmission diffraction section 60 at the second element section 52. Therefore, when the optical element 10 is observed using a rod-shaped light source, the condition under which the diffracted light transmitted by the first element section 51 is observed differs from the condition under which the diffracted light transmitted by the second element section 52 is observed. Variations of the fourth embodiment

[0167] The embodiment described above can be modified as follows. In the following description Fig. 35 and Fig. 36 For the sake of simplicity in explaining the reflective and transmitting sections of the optical element, the upper transparent plastic layer is not shown, and the reflective sections are shaded or hatched with dots.

[0168] At least one of the set of reflective sections 12 in the first element section 51 and the set of reflective sections 61 in the second element section 52 can be defined by cylindrical surfaces. That is, the structures of the first element section 51 can be combined with the reflective sections 31 of the second embodiment, and the structure of the second element section 52 can be combined with the reflective section 31 of the second embodiment. Alternatively, the reflective sections 12 in the first element section 51 can include both reflective sections with the non-periodic uneven structures as described above and reflective sections defined by cylindrical surfaces.The reflective sections 61 of the second element section 52 can include both reflective sections with the non-periodic uneven structures as described above and reflective sections defined by cylindrical surfaces.

[0169] Furthermore, the reflective sections 12 of the first element section 51 can have periodic uneven structures, and the reflective sections 61 of the second element section 52 can also have periodic uneven structures. That is, in an optical element, the structure of the first element section 51 can be combined with the reflective sections 41 of the third embodiment, and the structure of the second element section 52 can be combined with the reflective section 51 of the third embodiment.

[0170] With such a structure, the diffracted light resulting from the periodic uneven structures of the reflecting sections and the diffracted light resulting from the grating period of the transmission diffraction section are observed when observing reflected light. However, when observing transmitted light, only the diffracted light transmitted by the transmission diffraction section is observed. Therefore, in optical element 50, the grating period of the reflecting sections and the grating period d of the transmission diffraction section can be adjusted such that the wavelengths of the two diffracted light rays are combined, and shimmering diffracted light is not observed when observing reflected light.Furthermore, the grating period of the reflecting sections and the grating period of the transmission diffraction section can be adjusted such that properties including transmission angles and wavelengths of the two diffracted light beams are significantly different, making it possible to observe the two diffracted light beams in vivid colors.

[0171] If the reflecting sections 12 of the first element section 51 and the reflecting sections 61 of the second element section 52 exhibit periodic uneven structures and reflect diffracted light, the grating period of the reflecting sections 12 of the first element section 51 can be the same as or different from the grating period of the reflecting sections 61 of the second element section 52. Furthermore, the periodicity axis of the reflecting sections 12 of the first element section 51 can be the same as or different from the periodicity axis of the reflecting sections 61 of the second element section 52.

[0172] In a structure where the lattice period of the reflecting sections 12 in the first element section 51 differs from the lattice period of the reflecting sections 61 in the second element section 52, and in a structure where the periodicity axis of the reflecting sections 12 in the first element section 51 differs from the periodicity axis of the reflecting sections 61 in the second element section 52, the optical element 50 can be structured such that the diffraction light produced as reflection light by the first element section 51 and the diffraction light produced as reflection light by the second element section 52 are combined and emitted as white reflection light by the optical element 50.

[0173] If the reflecting sections 12 in the first element section 51 and the reflecting sections 61 in the second element section 52 have the periodic uneven structures and reflect diffracted light, at least one of the first element section 51 and the second element section 52 can have several types of reflecting sections that differ from each other in at least one of the periodicity axis and the lattice period in the uneven structure.

[0174] Furthermore, one of the set of reflecting sections 12 in the first element section 51 and the set of reflecting sections 61 in the second element section 52 may have non-periodic uneven structures or cylindrical surfaces and reflect scattered light, and the other may have periodic uneven structures and reflect diffracted light.

[0175] As in Fig. As shown in Figure 35, the positions of the reflecting sections and the transmitting sections can be seen in Fig. 34 be inverted. In other words, the optical element 50 comprises a single metal film formed over the lower transparent plastic layer 11, i.e., on the back surface 15r of the upper transparent plastic layer 15. The single metal film extends over both the first and second element sections 51 and 52.

[0176] The first element section 51 comprises a plurality of transmitting sections 13 arranged at equal intervals along the X-axis. Each transmitting section 13 is shaped like a strip extending along the Y-axis. Each of the reflecting sections 12a is sandwiched between corresponding pairs of transmitting sections 13 that are adjacent to each other along the X-axis.

[0177] The reflecting sections 12a and the transmitting sections 13 are arranged consecutively and alternately along the X-axis, forming a transmission diffraction section 20 which has a predetermined grating period da. In the first element section 51, the section of metal film surrounding the transmitting sections 13 also serves as a reflecting section 12b.

[0178] The second element section 52 comprises a plurality of transmitting sections 62 arranged at equal intervals along the Y-axis. Each transmitting section 62 is shaped like a strip extending along the X-axis. Each of the reflecting sections 61a is sandwiched between corresponding two transmitting sections 62 that are adjacent to each other along the Y-axis.

[0179] The reflecting sections 61a and the transmitting sections 62 are arranged consecutively and alternately along the Y-axis, forming a transmitting diffraction section 60 which has a predetermined grating period db. The grating period db of the second element section 62 is equal to the grating period da of the first element section 51. In the second element section 52, the section of metal film surrounding the transmitting sections 62 also serves as a reflecting section 61B.

[0180] The surface of the metal film of the optical element 50 comprises non-periodic uneven structures that are identical with respect to their properties. That is, the reflecting sections of the first element section 51 and the reflecting sections of the second element section 52 are identical with respect to the properties of their non-periodic uneven structures. Therefore, the scattered light produced as reflected light by the reflecting sections 12 of the first element section 51 is identical to the scattered light produced as reflected light by the reflecting sections 51 of the second element section 52.

[0181] Such an optical element 50 has the same advantages as the optical element 50 of the fourth embodiment. In the case of the intermediate element 50 as in Fig. As shown in Figure 35, the section of the metal film corresponding to the first element section 51 can differ from the section of the metal film corresponding to the second element section 52 with respect to the properties of their non-periodic uneven structures. That is, the non-periodic uneven structure of the transmission diffraction section 20, including the reflecting sections of the first element section 51, can differ from the non-periodic uneven structures of the transmission diffraction section 60, including the reflecting sections of the second element section 52.

[0182] In this structure, the two transmission diffraction sections exhibit different non-periodic uneven structures, resulting in the generation of different reflected light rays.

[0183] At the in Fig. In the optical element 50 shown in Figure 35, the metal film can have a periodic uneven structure and produce diffraction light as reflected light from the light incident on the optical element 50. That is, each of the reflecting sections of the first uneven structure 51 and the reflecting sections of the second element section 52 can have a periodic uneven structure. The section of the metal film corresponding to the first element section 51 can be the same as or different from the section of the metal film corresponding to the second element section 52 with respect to the properties of the periodic uneven structure. That is, the reflecting sections of the first element section 51 can be the same as or different from the reflecting sections of the second element section 52 with respect to the properties of a periodic uneven structure.

[0184] The in Fig. The optical element 50 shown in Figure 36 differs from the one in Figure 50. Fig. The optical element 50 shown in Figure 35 is characterized by the fact that the transmitting sections 52 of the second element section 52 have different lengths along the X-axis. For example, the lengths along the X-axis of the transmitting sections 62 gradually decrease from the transmitting section 62 located at one end on the Y-axis towards the transmitting section 62 located at the other end. The first element section 51 and the second element section 52 are symmetrical with respect to a ZX plane extending along the boundary between the first element section 51 and the second element section 52.

[0185] Alternatively, the transmitting sections 62 in the second element section 52 can include transmitting sections 62 of different lengths along the X-axis, and the transmitting sections 62 can be arranged along the Y-axis without a predetermined regularity with respect to a length along the X-axis.

[0186] In such a structure, the reflecting sections of the first and second element sections 51 and 52 can exhibit non-periodic uneven structures and scatter incident light, and the reflecting sections of the first element section 51 can be the same as or different from the reflecting sections of the second element section 52 with respect to the properties of their non-periodic uneven structures. Alternatively, the reflecting sections of the first and second element sections 51 and 52 can exhibit periodic uneven structures and diffract incident light, and the reflecting sections of the first element section 51 can be the same as or different from the reflecting sections of the second element section 52 with respect to the properties of their periodic uneven structure.

[0187] In optical element 50, the reflective sections 12 of the first element section 51 can have different lengths along the Y-axis, and the reflective sections 61 of the second element section 52 can have different lengths along the Y-axis. That is, the structure of optical element 50 can be combined with optical element 10 as shown in Fig. 13 shown combined, which is a modification or variation of the first embodiment.

[0188] In optical element 50, the structure of the first element section 51 in optical element 50 can be as shown in Fig. Figure 34 shows the structure of the second element section 52 of the optical element 50 as in Fig. 35 can be combined. Alternatively, the structure of the second element section 52 can be combined with the optical element 50 as shown in Fig. Figure 34 shows the structure of the first element section 51 of the optical element 50 as in Fig. Figure 35 shows how to combine the elements. In optical element 50, the transmission diffraction section of the first element section 51 can be identical to the transmission diffraction section of the second element section 52, and the non-periodic uneven structure of the reflecting sections of the first element section 51 can differ from the non-periodic uneven structure of the reflecting sections of the second element section 52. This structure allows the optical effect obtained by the first element section 51 to be different from the optical effect obtained by the second element section 52.

[0189] In the optical element, the transmission diffraction zone of the first element section 51 can be the same as the transmission diffraction zone of the second element section 52, and the periodic uneven structure of the reflecting sections in the first element section 51 can differ from the periodic uneven structure of the reflecting sections in the second element section 52 with respect to the grating period and the reflection period sections. This structure allows the optical effect obtained by the first element section 51 to be different from the optical effect obtained by the second element section 52.

[0190] If the grating period of the reflecting sections in the first element section 51 differs from the grating period of the reflecting sections in the second element section 52, the transmission diffraction sections can produce different diffraction light rays. Fifth embodiment

[0191] Referring to Fig. Section 37 below describes an optical element according to a fifth embodiment. The optical element of the fifth embodiment differs from the optical element of the fourth embodiment in that the grating period of the transmission diffraction section in the first element section differs from the grating period of the transmission diffraction section in the second element section. Therefore, the following description will focus on this difference. The same reference numerals are given to those components that are identical to the corresponding components of the optical element of the fourth embodiment. Such components are not described in detail. In the following description, the structure and operation of the optical element are described in that order. Structure of the optical element

[0192] Referring to Fig. Section 37 below describes the structure of the optical element. Fig. 37 For the sake of simplicity in explaining the reflective and transmitting sections of the optical element, the upper transparent plastic layer is not shown, and the reflective sections are shaded or hatched with dots.

[0193] As in Fig. As shown in Figure 37, an optical element 50 comprises a first element section 51 and a second element section 52. The first element section 51 comprises a plurality of reflecting sections 71 arranged at equal intervals along the Y-axis, which is an example of a given axis. Each reflecting section 71 is shaped like a strip extending along the X-axis. Each of the transmitting sections 72 is arranged between corresponding pairs of reflecting sections 71 that are adjacent to each other along the Y-axis. The transmitting sections 72 are arranged at equal intervals along the Y-axis. Each transmitting section 72 is shaped like a strip extending along the X-axis. Each reflecting section 71 has a non-periodic uneven structure.In the first element section 51, the ratio between the sum of areas of all reflecting sections 71 and the sum of areas of sections that transmit light, including the transmitting sections 72, is a first area ratio S1.

[0194] The reflecting sections 71 and the transmitting sections 72 are arranged consecutively and alternately along the Y-axis, forming a transmission diffraction section 70. In the transmission diffraction section 70, a reflecting section 71 and a transmitting section 72 that are adjacent to each other form a transmission period section 73, which has a predetermined grating period da.

[0195] The second element section 52 comprises a plurality of reflective sections 81 arranged at equal intervals along the Y-axis. Each reflective section 81 is shaped like a strip extending along the X-axis. Each of the transmitting sections 82 is arranged between corresponding pairs of reflective sections 81 that are adjacent to each other along the Y-axis. The transmitting sections 82 are arranged at equal intervals along the Y-axis. Each transmitting section 62 is shaped like a strip extending along the X-axis. Each reflective section 81 has a non-periodic uneven structure, identical in properties to the reflective sections 61 of the first element section 51.In the second element section 52, the ratio between the sum of areas of all reflecting sections 81 and the sum of areas of sections that transmit light, including the transmitting sections 82, is a second area ratio S2.

[0196] The reflecting sections 81 and the transmitting sections 82 are arranged consecutively and alternately along the Y-axis, forming a transmission diffraction section 80. Within the transmission diffraction section 80, an adjacent reflecting section 81 and a transmitting section 82 form a transmission period section 83, which has a predetermined grating period db. The grating period db of the transmission diffraction section 80 at the second element section 52 is smaller than the grating period da of the transmission diffraction section 80 at the first element section 51. Alternatively, the grating period db of the transmission diffraction section 80 at the second element section 52 can be larger than the grating period da of the transmission diffraction section 80 at the first element section 51. Operation of the optical element

[0197] If the first area ratio S1 is equal to the second area ratio S2 of the optical element 50, the intensity of the scattered light reflected by the first element section 51 is equal to the intensity of the scattered light reflected by the second element section 62. Furthermore, the reflecting sections 71 of the first element section 51 are identical to the reflecting sections 81 of the second element section 52 with respect to the properties of their non-periodic uneven structures. Therefore, the boundary between the first element section 51 and the second element section 52 is not easily perceptible when observing reflected light.

[0198] On the other hand, the grating period da of the transmission diffraction section 70 at the first element section 51 differs from the grating period db of the transmission diffraction section 80 at the second element section 52. Therefore, the diffracted light produced as transmitted light from incident light by the transmission diffraction section 70 at the first element section 51 differs from the diffracted light produced as transmitted light from incident light by the transmission diffraction section 80 in the second element section 52. As a result, when observing transmitted light, the diffracted light observed at the first element section 51 differs from the diffracted light observed at the second element section 52 with respect to a transmission angle and a scattering angle, which makes it easy to perceive the boundary between the first element section 51 and the second element section 52.

[0199] One advantage of the optical element of the fifth embodiment is described below.

[0200] (12) Since the grating period of the transfer diffraction section 70 at the first element section 51 differs from the grating period of the transfer diffraction section 80 at the second element section 52, the transfer diffraction sections produce different diffraction light rays. Variations of the fifth embodiment

[0201] The fifth embodiment described above can be modified as follows. In the embodiments described below... Fig. In figures 38 to 40, for the sake of simplicity in explaining the reflective and transmitting sections of the optical element, the upper transparent plastic layer is not shown, and the reflective sections are shaded with dots.

[0202] The first area ratio S1 in the first element section 51 can differ from the second area ratio S2 in the second element section 52.

[0203] Instead of the non-periodic uneven structure, the reflecting sections 71 of the first element section 51 and the reflecting sections 81 of the second element section 52 can exhibit periodic uneven structures and generate diffracted light as reflected light. With such a structure, as long as the reflecting sections 71 of the first element section 51 are identical to the reflecting sections 81 of the second element section 52 with respect to the properties of their periodic uneven structures, the diffracted light generated as reflected light by the first element section 51 is identical to the diffracted light generated as reflected light by the second element section 52. The boundary between the first element section 51 and the second element section 52 is difficult to perceive.

[0204] As in Fig. As shown in Figure 38, the positions of the reflecting sections and transmitting sections of the optical element 50 can be determined as in Figure 38. Fig. Figure 37 shows the optical element 50 inverted. That is, the optical element 50 comprises a single metal film formed over the lower transparent plastic layer 11, i.e., on the back surface 15r of the upper transparent plastic layer 15. The single metal film extends over both the first element section 51 and the second element section 52.

[0205] The first element section 51 comprises a plurality of transmitting sections 52 arranged at equal intervals along the Y-axis. Each transmitting section 72 is shaped like a strip extending along the X-axis. Each of the reflecting sections 71a is positioned between corresponding pairs of transmitting sections 72 that are adjacent to each other along the Y-axis. The reflecting sections 71a and the transmitting sections 72 are arranged consecutively and alternately along the Y-axis, forming a transmitting diffraction section 70. In the transmitting diffraction section 70, an adjacent reflecting section 71a and a transmitting section 72 form a transmitting period section 73, which has a predetermined grating period da.In the first element section 51, the section of the metal film surrounding the transmitting sections 72 also serves as a reflective section 71b.

[0206] The second element section 52 comprises a plurality of transmitting sections 82 arranged at equal intervals along the Y-axis. Each transmitting section 82 is shaped like a strip extending along the X-axis. Each of the reflecting sections 81a is positioned between corresponding two transmitting sections 82A that are adjacent to each other along the Y-axis.

[0207] The reflective sections 81a and the transmitting sections 82 are arranged consecutively and alternately along the Y-axis, forming a transmission diffraction section 80. In the transmission diffraction section 80, a reflective section 81a and a transmitting section 82, which are adjacent to each other, form a transmission period section 83, which has a predetermined grating period db. The grating period db of the second element section 52 is smaller than the grating period da of the first element section 51. In the second element section 52, the section of the metal film that surrounds the transmitting sections 82 also serves as a reflective section 81b.

[0208] Such a structure has the same advantages as the optical element 50 of the fifth embodiment.

[0209] As in Fig. As shown in Figure 39, the optical element 50 can have a cross-lattice structure. The optical element 50 comprises a first element section 51 and a second element section 52. In the first element section 51, a plurality of rectangular reflecting sections 91 are arranged at equal intervals along the X-axis and at equal intervals along the Y-axis. Transmitting sections 92 extend along the Y-axis and are arranged between each pair of reflecting sections 91 that are adjacent to each other along the X-axis.The reflecting sections 91 and the transmitting sections 92 are arranged consecutively and alternately along the X-axis and consecutively and alternately along the Y-axis. A plurality of reflecting sections 91 and a plurality of transmitting sections 92 thus form a transmission diffraction section 90. Furthermore, a reflecting section 91 and a transmitting section 92 that are adjacent to each other along the X-axis form a transmission period section 93, and a reflecting section 91 and a transmitting section 92 that are adjacent to each other along the Y-axis form a transmission period section 93.In the transmission diffraction section 90, the grating period along the periodicity axis parallel to the X-axis is equal to the grating period along the periodicity axis parallel to the Y-axis, and each grating period is a predetermined grating period.

[0210] In the second element section 52, a plurality of rectangular reflective sections 101 are arranged at equal intervals along the X-axis and at equal intervals along the Y-axis. Transmitting sections 102 extend along the Y-axis and are arranged between each pair of reflective sections 101 that are adjacent to each other along the X-axis. Furthermore, transmitting sections 102 extend along the X-axis and are arranged between each pair of reflective sections 101 that are adjacent to each other along the Y-axis.

[0211] The reflecting sections 101 and the transmitting section 102 are arranged consecutively and alternately along the X-axis and consecutively and alternately along the Y-axis. A plurality of reflecting sections 101 and a plurality of transmitting sections 102 therefore form a transmission diffraction section 100. Furthermore, a reflecting section 101 and a transmitting section 102 that are adjacent to each other along the X-axis form a transmission period section 103, and a reflecting section 101 and a transmitting section 102 that are adjacent to each other along the Y-axis form a transmission period section 103.In the transmission diffraction section 100, the grating period along the periodicity axis parallel to the X-axis is equal to the grating period along the periodicity axis parallel to the Y-axis, and each grating period is a predetermined grating period db. The grating period db of transmission diffraction section 100 at the second element section 52 is smaller than the grating period da of transmission diffraction section 90 at the first element section 51.

[0212] In such an optical element 50, the boundary between the first element section 51 and the second element section 52 is not easily perceived when viewing or observing reflected light. However, when observing transmitted light, the boundary between the first element section 51 and the second element section 52 can be easily perceived, since the diffracted light resulting from transmission through the first element section 51 differs from the diffracted light resulting from transmission through the second element section 52.

[0213] As in Fig. As shown in Figure 40, the positions of the reflecting sections and the transmitting sections of the optical element 50 can be determined. Fig. 39 are inverted. That is, the optical element 50 comprises a single metal film formed over the lower transparent plastic layer 11, i.e., on the back surface 15r of the upper transparent plastic layer 15. The single metal film extends over both the first element section 51 and the second element section 52.

[0214] In the first element section 51, a plurality of rectangular transmitting sections 92 are arranged at equal intervals along the X-axis and along the Y-axis. Reflective sections 91a extend along the Y-axis and are arranged between each pair of transmitting sections 92 that are adjacent to each other along the X-axis. The section of metal film surrounding the transmitting sections 92 also serves as a reflective section 91b.

[0215] The reflecting sections 91a and the transmitting sections 92 are arranged consecutively and alternately along the X-axis and consecutively and alternately along the Y-axis. A plurality of reflecting sections 91a and a plurality of transmitting sections 92 thus form a transmission diffraction section 90. Furthermore, a reflecting section 91a and a transmitting section 92 that are adjacent to each other along the X-axis form a transmission period section 93, and a reflecting section 91a and a transmitting section 92 that are adjacent to each other along the Y-axis form a transmission period section 93.In the transmission diffraction section 90, the grating period along the periodicity axis parallel to the X-axis is equal to the grating period along the axis parallel to the Y-axis, and each grating period is a predetermined grating period.

[0216] In the second element section 52, a plurality of rectangular transmitting sections 102 are arranged at equal intervals along the X-axis and at equal intervals along the Y-axis. Reflective sections 101a extend along the Y-axis and are arranged between each pair of transmitting sections 102 that are adjacent to each other along the X-axis. The section of metal film surrounding the transmitting sections 92 also serves as a reflective section 101b. The reflective sections 101a and the transmitting sections 102 are arranged consecutively and alternately along the X-axis and along the Y-axis.A plurality of reflecting sections 101 and a plurality of transmitting sections 102 thus form a transmission diffraction section 100. Furthermore, a reflecting section 101a and a transmitting section 102 that are adjacent to each other along the X-axis form a transmission period section 103, and a reflecting section 101a and a transmitting section 102 that are adjacent to each other along the Y-axis form a transmission period section 103. In the transmission diffraction section 100, the grating period along the periodicity axis parallel to the X-axis is equal to the grating period along the axis parallel to the Y-axis, and each grating period is a predetermined grating period db.The grating period db of the transmission diffraction section 100 at the second element section 52 is smaller than the grating period da of the transmission diffraction section 90 at the first element section 51. Such a structure has the same advantages as the optical element 50 as in . Fig. Figure 39 shows that the optical element 50 can be combined with the structure of the fourth embodiment. That is, the periodicity axis of the transmission diffraction section 70 in the first element section 51 can differ from the periodicity axis of the transmission diffraction section 80 in the second element section 52. Sixth embodiment

[0217] Referring to Fig. Section 41 below describes an optical element according to a sixth embodiment. The optical element of the sixth embodiment differs from the optical element of the fourth embodiment in the number of element sections that constitute the optical element. Therefore, the following descriptions will focus on this difference. The same reference numerals are given to those components that are identical to the corresponding components of the optical element of the fourth embodiment. Such components are not described in detail. The following description will describe the structure and operation of the optical element in that order. Structure of the optical element

[0218] Referring to Fig. Section 41 below describes the structure of the optical element. Fig. 41 For the sake of simplicity in describing the reflective and transmitting sections of the optical element, the upper transparent plastic layer is not shown, and the reflective sections are shaded with dots.

[0219] As in Fig. As shown in Figure 41, an optical element 110 comprises a first element section 111, a second element section 112, and a third element section 113, which are defined at the lower transparent plastic layer 11. The first element section 111 comprises a plurality of reflective sections 121 arranged at equal intervals along the Y-axis. Each reflective section 121 is shaped like a strip extending along the X-axis. Each of the transmitting sections 122 is arranged between corresponding two reflective sections 121 that are adjacent to each other along the Y-axis. Each transmitting section 122 is shaped like a strip extending along the X-axis.The reflecting sections 121 and the transmitting sections 122 are arranged consecutively and alternately along the Y-axis, forming a transmission diffraction section 120 which has a predetermined grating period PC. Each reflecting section 121 has a periodic uneven structure and produces red diffraction light as reflected light, for example.

[0220] In the same way as the first element section 111, the second element section 112 comprises a plurality of reflecting sections 131 arranged at equal intervals along the Y-axis. Each reflecting section 131 is shaped like a strip extending along the X-axis. Each of the transmitting sections 132 is arranged between corresponding pairs of reflecting sections 131 that are adjacent to each other along the Y-axis. Each transmitting section 132 is shaped like a strip extending along the X-axis. The reflecting sections 131 and the transmitting sections 132 are arranged consecutively and alternately along the Y-axis, forming a transmitting diffraction section 130 that has a predetermined grating period db.Each reflective section 131 exhibits a periodic uneven structure, which differs in its properties from the periodic uneven structure of the reflective section 121 in the first element section 111. For example, the reflective section 131 produces green diffraction light as reflected light.

[0221] In the same way as the first element section 111, the third element section 113 comprises a plurality of reflecting sections 141 arranged at equal intervals along the Y-axis. Each reflecting section 141 is shaped like a strip extending along the X-axis. Each of the transmitting sections 142 is arranged between corresponding pairs of reflecting sections 141 that are adjacent to each other along the Y-axis. Each transmitting section 142 is shaped like a strip extending along the X-axis. The reflecting sections 141 and the transmitting sections 142 are arranged consecutively and alternately along the Y-axis, forming a transmitting diffraction section 140 that has a predetermined grating period de.The lattice period de in the third element section 113, the lattice period dc in the first element section 111, and the lattice period dd in the second element section 112 are the same. However, the lattice periods in the three element sections do not necessarily have to be the same.

[0222] Each reflective section 141 exhibits a periodic uneven structure, which differs in its properties from both the uneven structure of the reflective section 121 in the first element section 111 and the uneven structure of the reflective section 131 in the second element section 112. For example, the reflective section 141 produces blue diffraction light as reflected light. Operation of the optical element

[0223] When light enters the transmission diffraction sections of the optical element 110 through the upper transparent plastic layer 15, the first element section 111 produces red diffraction light as reflected light, the second element section 112 produces green diffraction light as reflected light, and the third element section 113 produces blue diffraction light as reflected light. The reflected light emitted by the optical element 50 is a mixture of three diffraction light rays and is therefore white light.

[0224] The optical element 50 is able to generate white reflected light without including the reflecting sections that have non-periodic uneven structures and reflect scattered light, or the reflecting sections that have cylindrical surfaces and reflect scattered light.

[0225] One advantage of the optical element of the sixth embodiment is described below.

[0226] (13) The three element sections of the optical element 110 have different periodic uneven structures and therefore produce different diffraction rays as reflected light. Therefore, the optical element 110 emits white reflected light. Variations of the sixth embodiment

[0227] The sixth embodiment described above can be modified or adapted as follows. Fig. 42, which is described below, the upper transparent plastic layer is not shown for the sake of simplicity in explaining the reflective and transmitting sections of the optical element.

[0228] The optical element 110 is not limited to a structure in which white reflected light is generated by combining diffracted light rays. It is sufficient that the optical element 50 comprises three element sections that differ from each other in at least one by an optical effect resulting from reflection and another by an optical effect resulting from transmission.

[0229] As long as the optical element 110 has three or more element sections, the number of element sections is not limited. For example, the optical element 110 can have four element sections. As in Fig. As shown in Figure 42, an optical element 110 can have a first element section 111, a second element section 112, a third element section 113, and a fourth element section 114, which are defined on the lower transparent plastic layer 11. The first element section 111 comprises a plurality of reflective sections 121 arranged at equal intervals along the X-axis. Each reflective section is shaped like a strip extending along the Y-axis. In the first element section 111, each of the transmitting sections 122 is arranged between corresponding pairs of reflective sections 121 that are adjacent to each other along the X-axis. Each transmitting section 122 is shaped like a strip extending along the Y-axis.

[0230] The reflecting sections 121 and the transmitting sections 122 are arranged consecutively and alternately along the X-axis, forming a transmission diffraction section 120. In the transmission diffraction section 120, a reflecting section 121 and a transmitting section 122 that are adjacent to each other form a transmission period section 123, which has a predetermined grating period dc. The second element section 112 comprises a plurality of reflecting sections 131 that are arranged at equal intervals along the Y-axis. Each reflecting section 131 is shaped like a strip extending along the X-axis. In the second element section 112, each of the transmitting sections 132 is arranged between corresponding two reflecting sections 131 that are adjacent to each other along the Y-axis.Each transmitting section 132 is shaped like a strip extending along the X-axis.

[0231] The reflecting sections 131 and the transmitting sections 132 are arranged consecutively and alternately along the Y-axis, forming a transmission diffraction section 130. In the transmission diffraction section 130, a reflecting section 131 and a transmitting section 132 that are adjacent to each other form a transmission period section 133, which has a predetermined grating period db. The grating period dd is equal to the grating period dc of the transmission diffraction section 120 at the first element section 111. The periodicity axis of the transmission diffraction section 130 at the second element section 112 is perpendicular to the periodicity axis of the transmission diffraction section 120 at the first element section 111.

[0232] The third element section 113 comprises a plurality of reflective sections 141 arranged with identical elements along the X-axis. Each reflective section 141 is shaped like a strip extending along the Y-axis. In the third element section 113, each of the transmitting sections 142 is arranged between corresponding two reflective sections 141 that are adjacent to each other along the X-axis. Each transmitting section 142 is shaped like a strip extending along the Y-axis.

[0233] The reflecting sections 141 and the transmitting sections 142 are arranged consecutively and alternately along the X-axis, forming a transmission diffraction section 140. In the transmission diffraction section 140, a reflecting section 141 and a transmitting section 142, which are adjacent to each other, form a transmission period section 143, which has a predetermined grating period db. The grating period de of the transmission diffraction section 140 is larger than both the grating period dc of the transmission diffraction section 120 at the first element section 111 and the grating period db of the transmission diffraction section 130 at the second element section 112.

[0234] The fourth element section 114 comprises a plurality of reflective sections 151 arranged at equal intervals along the Y-axis. Each reflective section 151 is shaped like a strip extending along the X-axis. In the fourth element section 114, each transmitting section 152 is arranged between corresponding pairs of reflective sections 151 that are adjacent to each other along the Y-axis. Each transmitting section 152 is shaped like a strip extending along the X-axis.

[0235] The reflecting sections 151 and the transmitting sections 152 are arranged consecutively and alternately along the Y-axis, forming a transmission diffraction section 150. In the transmission diffraction section 150, a reflecting section 151 and a transmitting section 152, which are adjacent to each other, form a transmission period section 153, which has a predetermined grating period df. The grating period df is equal to the grating period de of the transmission diffraction section 140 at the third element section 113. The periodicity axis of the transmission diffraction section 140 at the fourth element section 114 is perpendicular to the periodicity axis of the transmission diffraction section 140 at the third element section 113.

[0236] Each reflective section in each element section consists of one reflective section having a non-periodic uneven structure and producing scattered light as reflected light, one reflective section having a cylindrical surface and producing scattered light as reflected light, and one reflective section having a periodic uneven structure and producing diffraction light as reflected light.

[0237] The four element sections of optical element 40 comprise sections that differ from each other in at least one aspect: the periodicity axis and the grating period of the transmission diffraction section. Therefore, different optical effects can be added to the individual optical element 50 up to the number of element sections. By adjusting the element sections to provide different optical effects when viewing reflected or transmitted light, optical element 50 can display a variety of reflection patterns and a variety of transmission patterns using scattered and diffracted light.

[0238] At least one of the three or more element sections of the optical element 110 can have a cross-lattice structure.

[0239] In the optical element 110 of the sixth embodiment and the modification of the optical element 110 of the sixth embodiment, the positions of the reflecting sections and the transmitting sections can be inverted. That is, the structure of the optical element 110 of the sixth embodiment and the structure of the optical element 110 of the modification of the sixth embodiment can be compared with the structure of the optical element 10 as shown in Fig. 14 can be combined, which is a modification of the first embodiment. Seventh embodiment

[0240] Referring to Fig. Section 43 below describes an optical element according to a seventh embodiment. The optical element of the seventh embodiment differs from the optical element of the fourth embodiment in that one of the two element sections forming the optical element does not produce diffracted light as transmitted light. Therefore, the following descriptions will focus on this difference. The same reference numerals are given to those components that are identical to the corresponding components of the optical element of the fourth embodiment. Such components are not described in detail. In the following description, the structure of the optical element and the operation of the optical element are described in that order. Structure of the optical element

[0241] Referring to Fig. 43 The structure of the optical element is described below. Fig. 43 For the sake of simplicity in explaining the reflective and transmitting sections of the optical element, the upper transparent plastic layer is not shown, and the reflective sections are shaded or hatched with dots.

[0242] As in Fig. As shown in Figure 43, an optical element 160 comprises a first element section 161 and a second element section 162. The first element section 161 comprises a plurality of reflecting sections 171 arranged at equal intervals along the Y-axis. Each reflecting section 171 is shaped like a strip extending along the X-axis. In the first element section 161, each of the transmitting sections 172 is arranged between corresponding pairs of reflecting sections 171 that are adjacent to each other along the Y-axis. Each transmitting section 172 is shaped like a strip extending along the X-axis. The reflecting sections 171 and the transmitting sections 172 are arranged consecutively and alternately along the Y-axis, forming a transmitting diffraction section 170. The transmitting diffraction section 170 has a predetermined grating period dg.

[0243] Each reflective section 171 has a non-periodic uneven structure and produces scattered light as reflected light. The reflective section 171 can have a cylindrical surface and produce scattered light as reflected light. For the first element section 161, the ratio between the sum of the areas of all reflective sections and the area of ​​sections that transmit light, including the transmitting sections 172, is a first area ratio S1.

[0244] The second element section 162 comprises a plurality of reflective sections 181 arranged irregularly along the Y-axis. Each reflective section 181 is shaped like a strip extending along the X-axis. The reflective sections 181 include reflective sections 181 of varying widths along the Y-axis. In the second element section 162, each of the transmitting sections 182 is arranged between corresponding pairs of reflective sections 181 that are adjacent to each other along the Y-axis. The transmitting sections 182 include transmitting sections 182 of varying widths along the Y-axis. Each transmitting section 182 is shaped like a strip extending along the X-axis. The reflective sections 181 and the transmitting sections 182 are arranged consecutively and alternately along the Y-axis.The reflective section 181 is an example of a scattering section, and the transferring section 182 is an example of a second transferring section.

[0245] Each reflective section 181 has a non-periodic uneven structure, identical in properties to the non-periodic uneven structure of the reflective sections 171 in the first element section 161, and produces scattered light as reflected light. Alternatively, the reflective section 181 can have a cylindrical surface and produce scattered light as reflected light. In the second element section 162, the ratio between the sum of the areas of all reflective sections 181 and the area of ​​sections that transmit light, including the transmitting sections 182, is a second area ratio S2. The first area ratio S1 is equal to the second area ratio S2. Effect of the optical element

[0246] The non-periodic uneven structure of the reflective sections 171 of the first element section 161 is identical in properties to the non-periodic uneven structure of the reflective sections 181 of the second element section 162. Furthermore, the first area ratio S1 of the first element section 161 is equal to the second area ratio S2. Therefore, when light falls on the reflective sections through the upper transparent plastic layer 15, the scattered light from the first element section 161 is identical to the scattered light from the second element section 162 when viewed as reflected light. Consequently, it is difficult to perceive the boundary between the first element section 161 and the second element section 162.The transmission diffraction section 170 at the first element section 161 produces diffracted light as transmitted light, however, the second element section 162 does not produce diffracted light as transmitted light. Consequently, when considering transmitted light, shimmering diffracted light is only observed at the first element section 161.

[0247] One advantage of the optical element of the seventh embodiment is described below.

[0248] (14) The light transmitted through the first element section 161 is diffracted light, forming diffraction patterns that differ from each other in color. In contrast, the light transmitted through the second element section 162 is white light. This illustrates the difference between the two types of light transmitted through the optical element 160. Variations of the seventh embodiment

[0249] The seventh embodiment described above can be modified as follows.

[0250] The reflective sections 171 of the first element section 161 and the reflective sections 181 of the second element section 162 can exhibit periodic uneven structures and generate diffracted light as reflected light. With this structure, as long as the reflective sections 161 of the first element section 161 are identical in properties to the reflective sections 181 of the second element section 162, the boundary between the first element section 161 and the second element section 162 is not easily perceived when viewing reflected light.

[0251] In optical element 160, the positions of the reflecting section 171 in the first element section 161 and the positions of the transmitting section 172 in the first element section 161 can be inverted, and the positions of the reflecting sections 181 in the second element section 162 and the positions of the transmitting section 182 in the second element section 162 can be inverted. Such a structure still has the same advantages as the optical element 160 of the seventh embodiment.

[0252] The optical element 160 can have a cross-grating structure. That is, as in Fig. As shown in Figure 44, an optical element 160 comprises a first element section 161 and a second element section 162. The first element section 161 comprises a plurality of rectangular reflecting sections 171 arranged at equal intervals along the X-axis and at equal intervals along the Y-axis. In the first element section 161, transmitting sections 172 extend along the Y-axis and are arranged between each pair of reflecting sections 171 that are adjacent to each other along the X-axis. Furthermore, transmitting sections 172 extend along the X-axis and are arranged between each pair of reflecting sections 171 that are adjacent to each other along the Y-axis.The reflecting sections 171 and the transmitting sections 172 are arranged consecutively and alternately along the X-axis and consecutively and alternately along the Y-axis to form a transmission diffraction section 170. The transmission diffraction section 170 has a predetermined grating period dg on both the periodicity axis parallel to the X-axis and the periodicity axis parallel to the Y-axis.

[0253] In the second element section 162, as seen along the Z-axis, a plurality of rectangular reflecting sections 181 are arranged irregularly along both the X- and Y-axes. In the second element section 162, transmitting sections 182 are arranged between each pair of reflecting sections 181 that are adjacent to each other along the X-axis. Furthermore, transmitting sections 182 are arranged between each pair of reflecting sections 181 that are adjacent to each other along the Y-axis. Such a structure continues to offer the same advantages as the optical element 160 of the seventh embodiment.

[0254] At the in Fig.In the optical element 160 shown in Figure 44, the positions of the reflecting sections 171 and the positions of the transmitting section 172 can be inverted in the first element section 161, and the positions of the reflecting sections 181 and the positions of the transmitting sections 182 in the second element section 162 can be inverted. Examples Example 1

[0255] First, an ultraviolet curing resin was prepared, containing 50.0 parts by mass of urethane (meth)acrylate, 30.0 parts by mass of methyl ethyl ketone, 20.0 parts by mass of ethyl acetate, and 1.5 parts by mass of a photoinitiator. Multifunctional urethane (meth)acrylate with a molecular weight of 6000 was used. Irgacure 184 (manufactured by BASF SE) was used as the photoinitiator.

[0256] The compound was applied to a transparent PET film with a thickness of 23 µm using engraved printing, so that the thickness of the compound film after drying was 1 µm.

[0257] Then, an uneven structure was formed using an original plate within the applied film of the compilation.

[0258] The original plate contained a multitude of first regions and a multitude of second regions. The first and second regions were rectangular and had a width of 5 µm along the latitude axis, which was a given axis, and a width of 20 mm along the longitude axis, which was perpendicular to the latitude axis. The first regions and the second regions were arranged sequentially and alternately along the latitude axis.

[0259] Each first region had a non-periodic uneven structure, exhibiting numerous depressions and ridges extending along the longitudinal axis. In this non-periodic uneven structure, the depressions and ridges were arranged sequentially and alternately along the latitude axis in a non-periodic manner. The average frequency of the non-periodic structure was 100 lines per millimeter, and the average depth of the depressions was 100 nm.

[0260] Every second region had a cross-lattice structure in which two periodic uneven structures intersected. One of the two periodic uneven structures contained a multitude of depressions extending along the longitudinal axis and a multitude of ridges extending along the longitudinal axis. The depressions and ridges were arranged alternately and periodically along the latitude axis. The other uneven structure contained a multitude of depressions extending along the latitude axis and a multitude of ridges extending along the latitude axis. The depressions and ridges were arranged alternately and periodically along the longitude axis. For each uneven structure, the spatial frequency was 2000 lines per millimeter, and the depth of the depressions was 200 nm.The aspect ratio of the uneven structure in the second area was greater than the aspect ratio of the uneven structure in the first area.

[0261] The original plate was supported on the cylindrical surface of the plate cylinder of the engraving press, and the applied film of the composition was irradiated with ultraviolet rays directed from the opposite side of the transparent PET film from the applied film of the composition, while the applied film was pressed onto the original plate. The ultraviolet resin in the composition was thus cured to create the upper transparent plastic layer. The printing pressure was set to 2 kgf / cm². 2The printing temperature was set to 80 °C, and the printing speed to 10 m / min. Ultraviolet radiation was generated using a high-temperature mercury lamp with an intensity of 300 mJ / cm². 2 directed.

[0262] Then, an aluminum film, which was a metal film used to form reflective sections, was vacuum-deposited onto the surface of the upper transparent plastic layer, which had the uneven structure described above. The thickness of the aluminum film was set to 50 nm. Next, a magnesium fluoride (MgF₂) film, acting as a mask layer for etching the aluminum film, was vacuum-deposited onto the surface of the aluminum film opposite the surface in contact with the upper transparent plastic layer. The thickness of the MgF₂ film was set to 20 nm.

[0263] The aluminum film was then etched using a sodium hydroxide solution. After etching, the sections of the aluminum film adjacent to the sections of the upper transparent plastic layer onto which the first regions of the original plate were transferred remained attached to the upper transparent plastic layer. In contrast, the sections of the aluminum film adjacent to the sections of the upper transparent plastic layer onto which the second regions of the original plate were transferred were selectively removed from the upper transparent plastic layer. A transfer diffraction zone, comprising both reflecting and transmitting sections and exhibiting a lattice period of 10 µm, was thus formed on the upper transparent plastic layer. Additionally, protective zones, overlapping the transmitting sections along the thickness axis, were also formed.

[0264] When reflecting light from the resulting optical element was observed, white light was seen scattered by the non-periodic, uneven structures of the reflecting sections. When transmitting light was observed, transmitted light of a vivid, iridescent color was seen, resulting from diffraction by the wireframe structure of the reflecting and transmitting sections, which are arranged alternately and periodically. Example 2

[0265] In Example 2, the first region of the original plate differed from the first region of the original plate in Example 1. The first region of the original plate in Example 2 comprised a multitude of depressions extending along the latitude axis and a multitude of ridges extending along the latitude axis. The depressions and ridges were arranged alternately along the longitude axis. That is, the first region had a diffraction pattern where the spatial frequency was 1000 lines per millimeter, and the depth of the depressions was 100 nm.

[0266] When observing reflected light from the optical element constructed using such an original plate, shimmering diffracted light was observed, diffracted by the periodic uneven structures of the reflecting sections. When observing transmitted light, transmitted light of a vivid, shimmering color was observed, resulting from diffraction by the wire grating structure of reflecting and transmitting sections arranged alternately and periodically. The diffracted light observed when observing reflected light differed from the diffracted light observed when observing transmitted light in the grating period and thus in wavelength scattering.As a result, the iridescent color of the light observed on the side of the upper transparent plastic layer opposite the reflective sections was different from the iridescent color of the light observed on the side of protective sections opposite the reflective sections. Example 3

[0267] Example 3 differed from Example 1 in that the original plate comprised a first section corresponding to a first element section, and a second section corresponding to a second element section.

[0268] The original plate of Example 3 comprised the first and second sections. In the first section, rectangular first regions were arranged periodically along the latitude axis and periodically along the longitude axis. The grid period along the latitude axis and the grid period along the longitude axis were 10 µm. In the second section, rectangular first regions were arranged irregularly. In the second section, second regions were arranged in sections that differed from those in which first regions were arranged. The sum of the areas of first regions in the first section was equal to that in the second section.

[0269] When observing reflected light from the optical element formed using such an original plate, scattered light was observed at both of the two element sections, and therefore the boundary between the two element sections was not perceived. When observing transmitted light, light of a vivid, iridescent color, resulting from diffraction through the cross-grating structure of the reflecting and transmitting sections, which were arranged alternately and periodically, was observed at one of the element sections. At the other element section, white light, transmitted through the non-periodic transmitting sections, was observed.

Claims

[1] Optical element (10, 50, 110, 160) with a transmission diffraction section (20, 60, 70, 80, 90, 100, 120, 130, 140, 150, 170), comprising a plurality of reflective sections (12, 12a, 31, 41, 61, 61a, 71, 71a, 81, 81a, 91, 91a, 101, 101a, 121, 131, 141, 151, 171) arranged at equal intervals along a given axis, each of the reflective sections reflecting light contained in visible light, and the light reflected by the reflective sections forming a reflection image, and a plurality of transmitting sections (13, 62, 72, 82, 92, 102, 122, 132, 142, 152, 172), each of which is clamped by two corresponding reflecting sections adjacent to each other along the given axis, wherein the transmitting sections transmit the visible light, wherein at least a part of each reflecting section forms the reflection image by reproducing a reflection angle of the light reflected by the reflecting sections that is different from an angle of light incident on the reflecting sections, The transmission diffraction section forms a multitude of diffraction patterns with different colors using diffracted light, which is generated by diffracting light transmitted through the transmitting sections in a predetermined direction. at least part of each reflective section (12, 12a) has a non-periodic uneven structure, The non-periodic uneven structure scatters visible light that falls upon it, and The scattered light emitted from the non-periodic, uneven structure forms the reflection image. [2] Optical element (10, 50, 110, 160) with a transmission diffraction section (20, 60, 70, 80, 90, 100, 120, 130, 140, 150, 170), comprising a plurality of reflective sections (12, 12a, 31, 41, 61, 61a, 71, 71a, 81, 81a, 91, 91a, 101, 101a, 121, 131, 141, 151, 171) arranged at equal intervals along a given axis, each of the reflective sections reflecting light contained in visible light, and the light reflected by the reflective sections forming a reflection image, and a plurality of transmitting sections (13, 62, 72, 82, 92, 102, 122, 132, 142, 152, 172), each of which is clamped by two corresponding reflecting sections adjacent to each other along the given axis, wherein the transmitting sections transmit the visible light, wherein at least a part of each reflecting section forms the reflection image by reproducing a reflection angle of the light reflected by the reflecting sections that is different from an angle of light incident on the reflecting sections, The transmission diffraction section forms a multitude of diffraction patterns with different colors using diffracted light, which is generated by diffracting light transmitted through the transmitting sections in a predetermined direction. at least a part of each reflective section (41) has a periodic uneven structure with a predetermined periodicity, The periodic uneven structure bends visible light incident on it in a predetermined direction, and The diffraction light emitted by the periodic uneven structure forms the reflection image. [3] Optical element (10) according to claim 2, wherein a section with the periodic uneven structure is a first periodic section (43), each reflective section (41) furthermore has a second periodic section with an uneven structure that differs from the first periodic section (43) with respect to periodicity, and visible light incident on each reflecting section (41) is diffracted by the first periodic section (43) in a direction different from the direction in which the visible light is diffracted by the second periodic section. [4] Optical element (50, 160) according to claim 1, with a first element section (51, 161) which includes the transmission diffraction section (20, 170), and a second element section (52, 162) comprising a plurality of scattering sections (61, 181) that scatter visible light, and a second transmitting section (62, 182) that occupies the space between the scattering sections (61, 181), wherein a ratio between a sum of areas of all the reflecting sections (12, 171) and a sum of areas of sections in the first element section (51, 161) that transmit visible light, is a first area ratio (S1), a ratio between a sum of areas of all the scattering sections (61, 181) and an area of ​​the second transferring section (62, 182) is a second area ratio (S2), the first area ratio (S1) is equal to the second area ratio (S2), and Light transmitted through the second element section (52, 162) differs from light transmitted through the first element section (51, 161). [5] Optical element (160) according to claim 4, wherein the scattering sections (181) are arranged irregularly in the second element section (162). [6] Optical element (10, 50, 110) according to any one of claims 1 to 5, wherein Each reflecting section (12, 12a, 31, 41, 61, 61a, 71, 71a, 81, 81a, 91, 91a, 101, 101a, 121, 131, 141, 151) and a corresponding transmitting section (13, 62, 72, 82, 92, 102, 122, 132, 142, 152) adjacent to the reflecting section along the given axis form a transmitting period section (17, 33, 44, 73, 83, 93, 103, 123, 133, 143, 153), and a width of the transmission period section along the given axis is greater than 0.20 µm and less than 0.35 µm. [7] Optical element (10, 50, 110) according to any one of claims 1 to 5, wherein Each reflecting section (12, 12a, 31, 41, 61, 61a, 71, 71a, 81, 81a, 91, 91a, 101, 101a, 121, 131, 141, 151) and a corresponding transmitting section (13, 62, 72, 82, 92, 102, 122, 132, 142, 152) adjacent to the reflecting section along the given axis form a transmitting period section (17, 33, 44, 73, 83, 93, 103, 123, 133, 143, 153), and a width of the transmission period section along the given axis between 0.35 µm and 20 µm inclusive. [8] Optical element (10) according to claim 2, wherein each reflective section (41) has depressions (41a) and elevations (41b) arranged consecutively and alternately along a periodicity axis, Each depression (41a) and a corresponding elevation (41b) adjacent to the depression (41a) along the periodicity axis form a reflection period section (43), and a width of the reflection period section (43) along the periodicity axis is greater than 0.20 µm and less than 0.35 µm. [9] Optical element (10) according to claim 2, wherein Each reflective section (41) comprises depressions (41a) and elevations (41b) arranged consecutively and alternately along a periodicity axis, Each depression (41a) and a corresponding elevation (41b) adjacent to the depression (41a) along the periodicity axis form a reflection period section (43), and a width of the reflection period section (43) along the periodicity axis is between 0.35 µm and 20 µm inclusive. [10] Optical element (50, 110) according to any one of claims 1 to 9, wherein the transmission diffraction section (70, 80, 90, 100, 120, 130, 140, 150) is one of a plurality of transmission diffraction sections, at each of the transmission diffraction sections each reflecting section (71, 71a, 81, 81a, 91, 91a, 101, 101a, 121, 131, 141, 151) and a corresponding of the transmission sections (72, 82, 92, 102, 122, 132, 142, 152), which is adjacent to the reflecting section along the given axis, form a transmission period section (73, 83, 93, 103, 123, 133, 143, 153), and The transmission diffraction sections differ from each other in a width of the transmission period sections along the given axis. [11] Optical element (50) according to claim 1, wherein the transmission diffraction section (20, 60) is one of a plurality of transmission diffraction sections (20, 60), and The transmission diffraction sections (20, 60) differ from each other in their non-periodic uneven structure. [12] Optical element (50) according to claim 2, wherein the transmission diffraction section (20, 60) is one of a plurality of transmission diffraction sections (20, 60), Each reflective section (12, 61) of each transmission diffraction section (20, 60) comprises depressions and elevations arranged consecutively and alternately along a periodicity axis, Each depression and a corresponding elevation adjacent to the depression along the periodicity axis form a reflection period section, and the transmission diffraction sections (20, 60) differ from each other in a width of the reflection period sections along the periodicity axis. [13] Optical element (10) according to any one of claims 1 to 12, further comprising a protective section (10, 32, 42) covering each reflective section (12, 31, 41), wherein Each reflective section (12, 31, 41) has a thickness of between 5 nm and 500 nm inclusive, and Each protective section (14, 32, 42) has a thickness of between 0.3 nm and 200 nm inclusive.

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