Radio wave-transmitting body and window material

Abstract

The present invention improves light transmissivity while maintaining radio wave transmissivity in a radio wave reflector. Provided is a translucent radio wave-transmitting body 4 that is disposed on a surface of a window material 1 comprising at least one transparent plate 2 and a metal layer 3 laminated on the at least one transparent plate 2, the radio wave-transmitting body 4 comprising an electroconductive layer 41 and a base material layer 43 supporting the electroconductive layer 41. The electroconductive layer 41 has a plurality of patterns 40 having an electroconductive region 41 and a non-electroconductive region 42 surrounding the electroconductive region 41, and the plurality of patterns 40 are arranged periodically in both the horizontal and vertical directions. In each pattern 40, a plurality of linear electroconductive patterns 410 and a plurality of translucent linear non-electroconductive patterns 420 are alternately formed along a first direction X in the electroconductive region 41.

Description

Radio wave transmission body and window material

[0001] The present invention relates to a radio wave transmission body disposed on the surface of a window material and a window material provided with the radio wave transmission body.

[0002] In mobile phones and wireless communications, radio waves in a frequency band of about 2 GHz or more and 300 GHz or less are used. Such radio waves with short wavelengths have strong directivity and are difficult to bend around obstacles. Therefore, in order to spread radio waves over a wide range, reflectors are provided on the surfaces of buildings such as the walls, floors, ceilings, and columns of buildings (hereinafter referred to as "walls, etc.").

[0003] A metal reflector that reflects radio waves is generally composed of a metal plate such as aluminum or copper. It is known that in the case of radio waves with short wavelengths, a metal reflector reflects with strong intensity in the specular reflection direction, but it is difficult to diffusely reflect radio waves, and it is difficult for radio waves to reach a wide area of space. In addition, metal reflectors are generally opaque. Since the other side cannot be seen from one side of the metal reflector, when such a metal reflector is used in a living room, the presence of the metal reflector is conspicuous, and when it is used in a window, the line of sight is blocked, which hinders the indoor atmosphere and deteriorates the landscape. As a reflector for radio waves that can reach a wide area of space while dealing with the deterioration of the atmosphere and landscape, there is, for example, the radio wave reflector described in Patent Document 1.

[0004] International Publication No. 2023 / 127710

[0005] In order to reflect radio waves, a metal conductive layer is provided on the reflector. On the other hand, the light transmittance is reduced by the metal conductive layer. In radio wave reflectors used for windows and living rooms, it is required to improve the light transmittance while maintaining the radio wave transmittance.

[0006] The present invention provides a technique for improving the light transmittance while maintaining the radio wave transmittance in a radio wave reflector.

[0007] To achieve the above objectives, the present invention encompasses the subject matter described in the following sections: (Section 1) A translucent radio wave permeator disposed on the surface of a window material comprising at least one transparent plate and a metal layer laminated on the at least one transparent plate, comprising: a conductive layer; and a base layer supporting the conductive layer, wherein the conductive layer is arranged periodically in a pattern having conductive regions and non-conductive regions surrounding the conductive regions, and in each of the patterns, a plurality of linear conductive patterns and a plurality of translucent linear non-conductive patterns are alternately formed in the conductive regions along a first direction. (Section 2) The radio wave permeator according to Section 1, wherein translucent linear non-conductive patterns are further formed in the conductive regions at equal intervals along a direction intersecting the first direction. (Section 3) The radio wave permeator according to Section 1, wherein linear conductive patterns are further formed in the conductive regions at equal intervals along a direction intersecting the first direction. (Section 4) The radio wave permeator according to Section 2 or 3, wherein the intersecting angle is 90 degrees. (5) The radio wave permeable material according to item 1, wherein the conductive region further comprises translucent linear nonconductive patterns formed at equal intervals along a plurality of directions intersecting the first direction. (6) The radio wave permeable material according to any one of items 1 to 5, wherein the nonconductive patterns are gaps between adjacent conductive patterns. (7) The radio wave permeable material according to item 1, wherein the conductive region is circular, polygonal, or annular in plan view. (8) The radio wave permeable material according to item 7, wherein the conductive region comprises a plurality of conductive regions arranged concentrically. (9) The radio wave permeable material according to item 7 or 8, wherein the conductive region is annular, and at least one gap is provided in a part of the conductive region. (10) The radio wave permeable material according to any one of items 7 to 9, wherein the first direction is radial or circumferential. (Item 11) A window material comprising: at least one transparent plate; a metal layer laminated on the at least one transparent plate; and a radio wave permeable material according to any one of items 1 to 10, attached to the transparent plate or the metal layer.

[0008] According to the present invention, it is possible to provide a technology that improves the light transmittance while maintaining the radio wave transmittance in a radio wave reflector.

[0009] This is a cross-sectional view of a window material according to an embodiment. This is a diagram showing the overall schematic configuration of a radio wave permeable body according to an embodiment. (A) is a plan view, and (B) is an enlarged view of part A of (A). This is a cross-sectional view of a radio wave permeable body according to an embodiment. This is a plan view of a radio wave permeable body according to an embodiment, and is an enlarged view of part B shown in Figure 2(B). This is a diagram for illustrating another example of the pattern of the conductive layer provided on the radio wave permeable body. This is a diagram for illustrating another example of the pattern of the conductive layer provided on the radio wave permeable body. This is a diagram for illustrating another example of the pattern of the conductive layer provided on the radio wave permeable body. This is a diagram for illustrating another example of the arrangement of a plurality of conductive patterns and a plurality of non-conductive patterns alternately formed in the conductive region. This is a cross-sectional view of a window material according to Modification 1. This is a cross-sectional view of a window material according to Modification 2. This is a photograph for comparing the visible light transmittance of the radio wave permeable body in Example 1. This is a graph showing the results of a numerical simulation regarding the radio wave transmittance of the radio wave permeable body performed in Example 1. This is a graph showing the results of a numerical simulation regarding the radio wave transmittance of the radio wave permeable body performed in Example 2. This is a graph showing the results of a numerical simulation regarding the radio wave transmittance of the radio wave permeable body performed in Example 3. This is a diagram for illustrating the pattern of the conductive region defined in the numerical simulation of Example 4. This graph shows the results of the numerical simulation regarding the radio wave transparency of the radio wave permeable material performed in Example 4.

[0010] <Embodiments> Hereinafter, embodiments of the present invention will be described with reference to the drawings. Refer to Figure 1. The window material 1 according to this embodiment has a translucent radio wave permeable material 4 arranged on its surface. Although the window material 1 according to this embodiment has a metal layer 3, which reduces the transmittance of radio waves over a wide frequency band, the radio wave transmittance is improved by having a radio wave permeable material 4, which is a metasurface film, arranged on its surface.

[0011] Refer to Figures 2 to 4. The radio wave permeable body 4 comprises a conductive layer 41 and a substrate layer 43 that supports the conductive layer 41. The conductive layer 41 is a pattern having conductive regions 41 and non-conductive regions 42 surrounding the conductive regions 41, and multiple such patterns are arranged periodically in the vertical and horizontal directions. In each pattern, multiple linear conductive patterns 410 and multiple translucent linear non-conductive patterns 420 are alternately formed in the conductive region 41 along a first direction. Thus, in this embodiment of the present invention, by alternately forming multiple linear conductive patterns 410 and multiple translucent linear non-conductive patterns 420 in the conductive region 41, light transmission is improved while maintaining radio wave transmission.

[0012] Radio waves are transmitted through the conductive region 41, which functions as a divided resonator. The wavelength of the target radio waves is several centimeters (for example, about 10 mm to about 150 mm), and the length of one side of the conductive region 41 is several millimeters (for example, about 5.265 mm). When viewed from the perspective of radio waves, even if a gap (non-conductive pattern 420) of micrometer size (for example, about 15 μm) is provided in the conductive region 41, the size of that gap is not affected by the transmission of radio waves from the perspective of radio waves, so there is no effect on the transmission of radio waves. This is because the wavelength of the target radio waves is several centimeters, the size of the gap provided in the conductive region 41 is micrometers, and the conductive region 41 before the gap is provided dominates the transmission of radio waves. In contrast, when viewed from visible light with a wavelength of several hundred nanometers, the size of the conductive region 41 is a large size that affects the transmission of visible light, and visible light cannot be transmitted. On the other hand, by providing a gap of micrometer size in the conductive region 41, visible light with a wavelength of several hundred nanometers can be transmitted through that gap. This improves light transmission while maintaining radio wave transmission.

[0013] First, we will describe the window material 1 on which the radio wave permeable material 4 is placed. Next, we will describe the various components of the window material 1, including the radio wave permeable material 4.

[0014] (Window material) As shown in Figure 1, the window material 1 is a double-glazed window having a plurality of transparent plates 2. The window material 1 comprises a plurality of transparent plates 2, a metal layer 3, and a radio wave transparent material 4. The window material 1 also includes spacers 5 that maintain the distance between the plurality of transparent plates 2.

[0015] As shown in Figures 2 and 3, the radio wave transparent body 4 comprises a base layer 43 attached to a transparent plate 2 or a metal layer 3, and a conductive layer 41 formed on the base layer 43.

[0016] The window material 1 according to this embodiment, with this configuration, can enhance radio wave transparency only for radio waves in a specific frequency band, even though the metal layer 3 reflects or blocks radio waves. Moreover, since it only requires attaching the radio wave permeable material 4 to an existing window material 1 with a laminated metal layer 3, the window material 1 can be manufactured with high manufacturability.

[0017] The window material 1 according to this embodiment can be used, for example, as window glass in buildings, as well as as skylights in doors, fixed windows in ceilings, floors, etc. Furthermore, the window material 1 according to this embodiment can be used not only in buildings, but also in windows of automobiles, aircraft, ships, trains, ropeways, etc.

[0018] In the window material 1, the specific frequency band of radio waves that can enhance radio wave transparency is preferably any radio wave belonging to the range of 0.5 GHz to 60 GHz. In this embodiment, the transparent plate 2 is set to have high radio wave transparency in the 5 GHz frequency band (3 GHz to 5 GHz, 25 GHz to 30 GHz). However, there are no particular restrictions on the frequency band in which the radio wave transparency is to be enhanced in the window material 1. The specific frequency band in which the radio wave transparency is to be enhanced can be set to the desired frequency band by changing the shape of the conductive layer 41 in the radio wave transparent body 4.

[0019] (Transparent Plate 2) Transparent plate 2 is a transparent plate material. In this specification, "transparent" means that the light transmittance is 10% or more of the peak wavelength of the light before incidence, preferably 50% or more, and more preferably 80% or more. In other words, "semi-transparent" with a light transmittance of, for example, about 30% of the peak wavelength of the light before incidence is also included in "transparent" as defined in this specification. Furthermore, transparent plate 2 is not limited to being colorless and transparent, but may be colored.

[0020] In this embodiment, the transparent plate 2 is preferably a glass plate. Examples of glass plates include float glass, patterned glass, frosted glass, wired glass, and tempered glass. However, in addition to glass plates, the transparent plate 2 can also be an acrylic plate, a polycarbonate plate, or the like.

[0021] There are no particular restrictions on the shape of the transparent plate 2. The shape of the transparent plate 2 may be, for example, rectangular, circular, pentagonal, hexagonal, or elliptical in plan view. Here, "plan view" means viewing the main surface of the transparent plate 2 from a direction perpendicular to that main surface.

[0022] As shown in Figure 1, the multiple transparent plates 2 are arranged at regular intervals in the thickness direction of the window material 1. Of the adjacent transparent plates 2, one transparent plate 2 is sometimes referred to as the "first transparent plate 21" and the other transparent plate 2 as the "second transparent plate 22".

[0023] A spacer 5 is placed between the first transparent plate 21 and the second transparent plate 22. The spacer 5 maintains the distance between the two adjacent transparent plates 21 and 22. The outer periphery of the multiple transparent plates 2 is surrounded by a sealing material (not shown), and the space (intermediate layer 6) between the two adjacent transparent plates 21 and 22 is formed in an airtight manner. Preferably, the intermediate layer 6 is filled with an insulating gas. Examples of insulating gases include inert gases such as argon gas. However, the intermediate layer 6 may be filled with air. The intermediate layer 6 may also be a vacuum.

[0024] The first transparent plate 21 has a first surface 211 and a second surface 212. Similarly, the second transparent plate 22 has a first surface 221 and a second surface 222. The first surfaces 211 and 221 are one of the surfaces (main surfaces) in the thickness direction of the transparent plate 2. The second surfaces 212 and 222 are the main surfaces opposite to the first surfaces 211 and 221. In this embodiment, the first surfaces 211 and 221 refer to surfaces that face each other in adjacent transparent plates 2 (inner surfaces in the thickness direction of the window material 1), and the second surfaces 212 and 222 refer to outer surfaces of the window material 1.

[0025] In this embodiment, the window material 1 is a double-glazed glass consisting of two transparent plates 2, but it may also be a triple-glazed glass consisting of three transparent plates 2, or it may be composed of four or more transparent plates 2.

[0026] (Metal layer 3) The metal layer 3 is laminated on the transparent plate 2 to improve the heat insulation of the window material 1. The metal layer 3 is preferably a Low-E film. There are no particular restrictions on the Low-E film, but examples include a film in which a transparent dielectric layer, an infrared reflective layer, and a transparent dielectric layer are laminated in that order. Examples of transparent dielectric layers include metal oxides (e.g., zinc oxide, tin oxide) and metal nitrides. Examples of infrared reflective layers include metal films (e.g., silver) and semiconductor films.

[0027] The metal layer 3 can be laminated on any of the multiple transparent plates 2. In this embodiment, it is laminated on the first surface 211 of the first transparent plate 21. The metal layer 3 is laminated over the entire surface of the first surface 211 of the transparent plate 2. The metal layer 3 is laminated on the transparent plate 2 by, for example, coating, vapor deposition, adhesion, welding, etc.

[0028] (Radio wave permeable material 4) The radio wave permeable material 4 is attached to the transparent plate 2 or the metal layer 3. By attaching the radio wave permeable material 4 to the transparent plate 2 or the metal layer 3, the radio wave permeability of the window material 1 can be increased in a specific frequency band of radio waves. As shown in Figures 2 and 3, the radio wave permeable material 4 is laminated in the following order: a base material layer 43, a conductive layer 41, and a protective film 45. In this embodiment, the radio wave permeable material 4 is attached to the second surface 212 of the first transparent plate 21. The radio wave permeable material 4 may cover the entire surface of the transparent plate 2, or it may be attached to only a part of the entire surface.

[0029] (Base layer 43) The base layer 43 supports the conductive layer 41. In this embodiment, the base layer 43 is transparent. The base layer 43 is attached to the transparent plate 2 or the metal layer 3. On the surface of the base layer 43 opposite to the conductive layer 41, an adhesive layer (hereinafter referred to as the first adhesive layer 46) is provided. The first adhesive layer 46 preferably has a structure in which, before bonding, it has a number of capsules filled with adhesive, and when pressure is applied from the base layer 43 toward the transparent plate 2 or the metal layer 3 during bonding, the capsules burst and bonding is possible. However, the first adhesive layer 46 may be an adhesive that is applied without being filled into capsules. Examples of adhesives include synthetic resins such as acrylic resin, silicone resin, and polyvinyl alcohol resin.

[0030] As shown in Figure 2, the outer shape of the base layer 43 in this embodiment is rectangular (more specifically, square) in plan view. However, there are no particular restrictions on the shape of the base layer 43; for example, in addition to polygons, it can be circular, elliptical, star-shaped, heart-shaped, etc. The thickness of the base layer 43 is uniform throughout. However, the thickness of the base layer 43 does not have to be uniform.

[0031] Examples of the base material layer 43 include synthetic resins, FRP (Fiber Reinforced Plastics), carbon, glass, etc. Examples of synthetic resins include one or more selected from the group consisting of PET (polyethylene terephthalate), polyethylene, polypropylene, polyvinyl chloride, polystyrene, polymethyl methacrylate, polyester, polyformaldehyde, polyamide, polyphenylene ether, vinylidene chloride, polyvinyl acetate, polyvinyl acetal, AS resin, ABS resin, acrylic resin, fluororesin, nylon resin, polyacetal resin, polycarbonate resin, polyamide resin, and polyurethane resin. The base material layer 43 may also be a composite material of these synthetic resins. In this embodiment, the base material layer 43 is composed of a PET film.

[0032] The thickness of the base layer 43 is preferably 5 μm or more, more preferably 10 μm or more, and even more preferably 20 μm or more. On the other hand, the upper limit of the thickness of the base layer 43 is preferably 500 μm or less, more preferably 130 μm or less, and even more preferably 100 μm or less.

[0033] The base layer 43 is preferably flexible. The Young's modulus of the base layer 43 is preferably 0.01 GPa or more, more preferably 1 GPa or more, and even more preferably 8 GPa or more. On the other hand, the upper limit of the Young's modulus of the base layer 43 is preferably 80 GPa or less, more preferably 30 GPa or less, and even more preferably 20 GPa or less.

[0034] (Conductive layer 41) The conductive layer is a metallic microstructure portion consisting of a structure finer than the wavelength of the target radio wave (electromagnetic wave). The conductive layer corresponds to a split ring resonator in a metasurface (metamaterial) and is also called a split ring resonator (SRR). In this specification, the periodic pattern 40 formed by the conductive layer 41 may be referred to as the "split ring resonant section" or simply the "resonant section".

[0035] The conductive layer 41 contains a conductor and constitutes a transparent surface. The conductive layer 41 is formed on the substrate layer 43. As a method for forming the conductive layer 41 on the substrate layer 43, for example, a thin film in which the conductive layer 41 is embedded in a thin film dielectric is laminated on the substrate layer 43, or the conductive layer 41 is formed on the substrate layer 43 without using a dielectric.

[0036] Examples of conductors constituting the conductive layer 41 include one or more of silver, gold, copper, platinum, aluminum, titanium, silicone, indium tin oxide, and alloys (for example, alloys containing nickel, chromium, and molybdenum). Examples of alloys containing nickel, chromium, and molybdenum include various grades such as Hastelloy B-2, B-3, C-4, C-2000, C-22, C-276, G-30, N, W, and X.

[0037] The thickness of the conductive layer 41 is preferably 10 nm or more, more preferably 30 nm or more, and even more preferably 100 nm or more. On the other hand, the upper limit of the thickness of the conductive layer 41 is preferably 10 μm or less, more preferably 5 μm or less, and even more preferably 4 μm or less. When the thickness of the conductive layer 41 is 10 nm or more, an appropriate radio wave intensity can be ensured.

[0038] The conductive layer 41 preferably has a relative permittivity of 7 or higher. On the other hand, the upper limit of the relative permittivity is preferably 10,000 or less.

[0039] (Pattern of conductive layer 41) The conductive layer 41 is arranged in a plan view pattern, for example, as shown in Figure 2(B) and Figure 4. In this specification, when describing the conductive layer 41 with respect to the plan view pattern, the conductive layer 41 is referred to as the conductive region 41.

[0040] As shown in Figure 2(B), the radio wave permeable material 4 (metasurface film 4) has a plurality of divided ring resonant portions 40 (resonant portions 40) formed periodically in the vertical and horizontal directions. As shown in Figure 4, the resonant portions 40 have conductive regions 41 and non-conductive regions 42. In this embodiment, in the resonant portion 40, the conductive region 41 is rectangular (square) in plan view and is demarcated by the non-conductive region 42. In this embodiment, the non-conductive region 42 is a linear region, and the conductive region 41 is surrounded by two regions 42 (42A) along the horizontal direction and two regions 42 (42B) along the vertical direction. In this way, the conductive layer 41 constitutes the divided ring resonant portions 40 in the metasurface film 4, and the resonant portions 40 are arranged periodically in the vertical and horizontal directions in a pattern having conductive regions 41 and non-conductive regions 42. The outer edge 400 of one resonant region 40 is located in the center of the width direction of each non-conductive region 42 (42A, 42B), as shown by the dashed line in Figure 4. As exemplary dimensions, in this embodiment, the line width L6 of the non-conductive region 42 is approximately 0.4 mm, and the length L7 of one side of the rectangular (square) conductive region 41 is, for example, approximately 5.265 mm. The non-conductive region 42 may be filled with adhesive from the adhesive layer 44. The non-conductive region 42 can also be called the region without the conductive layer 41.

[0041] As shown in Figure 4, each conductive region 41 constituting the resonant portion 40 has multiple conductive patterns 410 and multiple non-conductive patterns 420 formed alternately. The non-conductive patterns 420 are translucent. This improves light transmission while maintaining radio wave transmission. In the illustrated example, the conductive patterns 410 and non-conductive patterns 420 are arranged along the X-axis in the figure. As exemplary dimensions, in this embodiment, the width L8 of the conductive pattern 410 is approximately 25 μm, and the width L9 of the non-conductive pattern 420 is approximately 15 μm.

[0042] (Protective Film 45) The protective film 45 can protect the conductive layer 41 by covering the conductive layer 41. The protective film 45 has a size corresponding to the base material layer 43 in a plan view. Examples of the protective film 45 include films made of synthetic resin and the like. Examples of the synthetic resin include one or more selected from the group consisting of PET (polyethylene terephthalate), COP (cycloolefin polymer), polyethylene, polypropylene, polyvinyl chloride, polystyrene, polymethyl methacrylate, polyester, polyformaldehyde, polyamide, polyphenylene ether, vinylidene chloride, polyvinyl acetate, polyvinyl acetal, AS resin, ABS resin, acrylic resin, fluororesin, nylon resin, polyacetal resin, polycarbonate resin, polyamide resin, and polyurethane resin.

[0043] The protective film 45 preferably contains fluorine. According to the protective film 45 containing fluorine, since it can prevent the transmission of ultraviolet rays, the conductive layer 41 can be protected from ultraviolet rays.

[0044] The thickness of the protective film 45 is preferably 5 μm or more, more preferably 10 μm or more, and still more preferably 15 μm or more. On the other hand, as the upper limit value of the thickness of the protective film 45, 100 μm or less is preferable, more preferably 50 μm or less, and still more preferably 25 μm or less.

[0045] The protective film 45 is adhered to the base material layer 43 via an adhesive layer (hereinafter referred to as the second adhesive layer 44). Examples of the second adhesive layer 44 include synthetic resin, rubber-based adhesive sheets, and the like. Examples of the synthetic resin include acrylic resin, silicone resin, polyvinyl alcohol resin, and the like.

[0046] <Modification Example> The above embodiment is only one of various embodiments of the present invention. The embodiment can be variously modified according to design and the like as long as the object of the present invention can be achieved. Hereinafter, modification examples of the embodiment will be listed. The modification examples described below can be applied in appropriate combinations.

[0047] (Another Example of the Pattern of the Conductive Layer 41) FIGS. 5 to 8 are diagrams for explaining another example of the pattern 40 (resonant portion 40) of the conductive layer 41 (conductive region 41) provided in the radio wave transmission body 4.

[0048] In the present embodiment, in the conductive region 41 constituting each resonant portion 40, as shown in FIG. 4, a plurality of conductive patterns 410 and a plurality of non-conductive patterns 420 arranged along the X-axis direction in the figure are alternately formed.

[0049] In another embodiment, as shown in FIG. 5(A), a linear non-conductive pattern 420 having translucency is further formed in the conductive region 41 shown in FIG. 4 at substantially equal intervals along the Y-axis direction intersecting the X-axis direction in the figure. Thereby, in the conductive region 41 constituting each resonant portion 40, each conductive pattern 410 can be formed into a rectangular island shape. The angle formed by the X-axis direction and the Y-axis direction is 90 degrees.

[0050] Further, in such a conductive region 41 shown in FIG. 5(A), for example, a linear non-conductive pattern 420 having translucency is further formed at substantially equal intervals along a direction M (represented by an arrow M in the figure) that makes an angle of 45 degrees with the X-axis direction and the Y-axis direction. Then, each conductive pattern 410 can be formed into a triangular island shape, a hexagonal island shape, or a polygonal island shape. When the interval between the non-conductive patterns 420 formed additionally along the direction M is narrowed, the conductive pattern 410 becomes a hexagonal island shape, and when it is widened, it becomes a triangular island shape.

[0051] Still further, in another embodiment, as shown in FIG. 5(B), linear conductive patterns 410 may be further formed in the conductive region 41 shown in FIG. 4 at substantially equal intervals along the Y-axis direction intersecting the X-axis direction in the figure.

[0052] In yet another embodiment, in each resonant portion 40, the conductive region 41 may be circular or polygonal in plan view, or, as shown in Figures 6 and 7, it may be annular (circular or elliptical annular, or polygonal annular) in plan view. The conductive region 41 may comprise a plurality of conductive regions 41C, 41D arranged concentrically. At least one gap 422 may be provided in a part of the conductive region 41. In the conductive region 41, a plurality of linear conductive patterns 410 and a plurality of translucent linear nonconductive patterns 420 may be arranged alternately along the X-axis direction in the figure, or alternately along the radial or circumferential direction.

[0053] In the example shown in Figure 6(A), the conductive region 41 is annular, and a gap 422 between the non-conductive region 42 is present in part of the ring. Figure 6(B) is a partially enlarged view of the conductive region 41 shown in Figure 6(A). In the example shown in Figure 6(B), the conductive region 41 has multiple conductive patterns 410 and multiple non-conductive patterns 420 arranged alternately along the X-axis in the figure.

[0054] As exemplary dimensions, the inner radius L10 of the annular conductive region 41 is approximately 8.75 mm, its width L11 is approximately 1 mm, and the width L12 of the gap 422 is approximately 0.2 mm. The width L13 of the conductive pattern 410 is approximately 25 μm, and the width L14 of the non-conductive pattern 420 is approximately 25 μm. The closest proximity distance L15 between the outer circumference of the annular conductive region 41 and the resonant portion 40 is approximately 5 mm.

[0055] In the example shown in Figure 7(A), the conductive region 41 is a concentric ring, comprising an inner annular conductive region 41C and an outer annular conductive region 41D. These two conductive regions 41C and 41D are arranged concentrically. The conductive region 41C has a gap 422C between a non-conductive region 42 in part of the ring, and the conductive region 41D has a gap 422D between a non-conductive region 42 in part of the ring. Figure 7(B) is a partially enlarged view of the conductive region 41 shown in Figure 7(A). In the example shown in Figure 7(B), as in the example shown in Figure 6(B), a plurality of conductive patterns 410 and a plurality of non-conductive patterns 420 are alternately formed in the conductive region 41, arranged along the X-axis direction in the figure.

[0056] As exemplary dimensions, the inner radius L16 of the annular conductive region 41C is approximately 1.25 mm, and the distance L17 between the outer circumference of the annular conductive region 41C and the inner circumference of the annular conductive region 41D is approximately 6.5 mm. In the example shown in Figure 7, the dimensions indicated by reference numerals L11 to L15 in Figure 7 are the same as the dimensions shown in Figure 6.

[0057] Figure 8 illustrates another example of the arrangement of multiple conductive patterns 410 and multiple non-conductive patterns 420 that are alternately formed in the conductive region 41.

[0058] The multiple conductive patterns 410 and multiple non-conductive patterns 420 are not limited to being arranged along the X-axis direction in the figures, as illustrated in Figures 6(B) and 7(B). The multiple conductive patterns 410 and multiple non-conductive patterns 420 only need to be formed alternately along a certain direction. As shown in Figure 8(A), the multiple conductive patterns 410 and multiple non-conductive patterns 420 can be arranged substantially radially along the radial direction of the annular conductive region 41 (the direction indicated by the symbol r in Figures 6 and 8). Alternatively, as shown in Figure 8(B), the multiple conductive patterns 410 and multiple non-conductive patterns 420 can be arranged substantially concentrically along the circumferential direction of the annular conductive region 41 (the direction indicated by the symbol θ in Figures 6 and 8).

[0059] (Modification 1) In the above embodiment, the window material 1 had a plurality of transparent plates 2, but as shown in Figure 9, the window material 1 may have only one transparent plate 2. As shown in Figure 9, a metal layer 3 is laminated on the first surface 211 of the transparent plate 2. The radio wave permeable material 4 is attached to the metal layer 3. The radio wave permeable material 4 may also be attached to the second surface 212 where the metal layer 3 is not provided.

[0060] Furthermore, the metal layer 3 is not limited to a Low-E film, but may also be a heat-shielding film. If the metal layer 3 is a heat-shielding film, for example, it may be attached to the first surface 211 or the second surface 212 of the transparent plate 2 after the window material 1 has been installed in the window frame.

[0061] (Modification 2) In the above embodiment, the radio wave permeable body 4 was attached to a transparent plate 2 (first transparent plate 21) on which the metal layer 3 was laminated. However, as shown in Figure 10, the radio wave permeable body 4 may be attached to a transparent plate 2 (second transparent plate 22) that is different from the transparent plate 2 on which the metal layer 3 was laminated.

[0062] The distance between the radio wave permeable material 4 and the metal layer 3 is preferably 110 mm or less, more preferably 30 mm or less, and even more preferably 10 mm or less. On the other hand, the lower limit of the distance between the radio wave permeable material 4 and the metal layer 3 may be 0 mm. That is, the radio wave permeable material 4 may be directly bonded to the metal layer 3 (see Figure 9).

[0063] <Example 1>

[0064] In this embodiment, the performance of the radio wave permeable material was evaluated. As an embodiment of the present invention, a sample of a radio wave permeable material according to one embodiment of the present invention, described with reference to Figures 2 to 4, was prepared. As a comparative example, a sample of a radio wave permeable material identical to the embodiment of the present invention was also prepared, except that the entire conductive region 41 is a conductive pattern 410 (no multiple non-conductive patterns 420 are formed in the conductive region 41).

[0065] Figure 11 is a photograph comparing the visible light transmittance of radio wave permeable materials. Figure 11(A) is a photograph of a conventional radio wave permeable material according to a comparative example, and Figure 11(B) is a photograph of a radio wave permeable material according to an embodiment of the present invention. In each of the photographs shown in Figure 11, the respective radio wave permeable material was superimposed on the vertically upper side of a printed material containing multiple characters, and the image was taken from the vertically upper side.

[0066] The transmittance of visible light will be examined based on the image shown in Figure 11. As shown in Figure 11(A), in conventional radio wave permeable materials, light is reflected from the surface of the radio wave permeable material, making it impossible to see the characters written on the printed material. In contrast, as shown in Figure 11(B), in the radio wave permeable material of the present invention, the characters written on the printed material could be seen. The characters were clearly visible. This confirms that the radio wave permeable material according to the embodiment of the present invention transmits visible light.

[0067] Next, the extent to which the radio wave transmittance is improved by placing the radio wave permeable material of the present invention on the surface of the window material was confirmed by numerical simulation. The numerical simulation was performed based on a waveguide model. In the radio wave permeable material included in the waveguide model, the conductive layer pattern (i.e., the metastructure conditions) shown in Figures 2 to 4 was defined, and the radio wave intensity transmitted through the window material was calculated in this defined waveguide model. As a comparative example, the same radio wave permeable material as in the embodiment of the present invention was used, except that the entire conductive region 41 is a conductive pattern 410 (no multiple non-conductive patterns 420 are formed in the conductive region 41), and the radio wave intensity transmitted through the window material was similarly defined and calculated.

[0068] Figure 12 is a graph showing the results of a numerical simulation regarding the radio wave transmittance of a radio wave permeable material. In the figure, the waveform indicated by reference numeral 91 is the calculation result for the radio wave permeable material of the embodiment of the present invention, and the waveform indicated by reference numeral 99 is the calculation result for the radio wave permeable material of the comparative example. The vertical axis of the graph represents the radio wave transmittance to the metal layer 3 (Low-E film) provided in the window material 1 shown in Figure 1.

[0069] The radio wave penetration performance will be examined based on the results of the numerical simulation shown in Figure 12. As shown in Figure 12, it was confirmed that the radio wave penetration performance is generally maintained in the 5G frequency band (3 GHz to 5 GHz).

[0070] As shown in Figures 11 and 12 above, it has been confirmed that the radio wave permeable material according to the embodiment of the present invention improves the transmittance of visible light while maintaining the transmission performance of radio waves.

[0071] <Example 2>

[0072] In this embodiment, the change in radio wave transmission performance due to the presence or absence of a linear non-conductive pattern 420 formed in the conductive region 41 was evaluated. A radio wave transparent body having a pattern of two annular conductive regions 41C and 41D, as described with reference to Figure 7, was designated as an embodiment of the present invention (Embodiment 2), and numerical simulations of the radio wave transmission performance were performed for this Embodiment 2. The numerical simulations were performed in the same manner as in Embodiment 1 based on a waveguide model. As a comparative example, a radio wave transparent body identical to Embodiment 2 of the present invention except that the entire conductive region 41C and 41D is a conductive pattern 410 (no multiple non-conductive patterns 420 are formed in the conductive region 41C and 41D) was also used, and the waveguide model was defined to calculate the radio wave intensity transmitted through the window material.

[0073] Figure 13 is a graph showing the results of a numerical simulation regarding the radio wave transmittance of a radio wave permeable material. In the figure, the waveform indicated by reference numeral 92 is the calculation result for the radio wave permeable material of the embodiment of the present invention, and the waveform indicated by reference numeral 98 is the calculation result for the radio wave permeable material of the comparative example. The vertical axis of the graph represents the radio wave transmittance to the metal layer 3 (Low-E film) provided in the window material 1 shown in Figure 1.

[0074] The change in radio wave transmission performance will be examined based on the results of the numerical simulation shown in Figure 13. As shown in Figure 13, it was shown that even in the configuration of the embodiment in which visible light transmission is given by providing a linear non-conductive pattern 420 in the conductive region 41, radio wave transmission can be provided.

[0075] As shown in Figure 13, the radio wave transparent material according to the embodiment of the present invention has been shown to improve the transmittance of visible light while maintaining the transmission performance of radio waves.

[0076] <Example 3>

[0077] In this embodiment, the change in radio wave transmission performance due to a change in the distance between two concentrically arranged annular conductive regions 41C and 41D of the conductive region 41 was evaluated. Similar to Embodiment 2, a radio wave transparent body having the pattern of two annular conductive regions 41C and 41D described with reference to Figure 7 was designated as Embodiment 3 of the present invention. For Embodiment 3, numerical simulations of radio wave transmission performance were performed by varying the dimensions indicated by reference numeral 17 in Figure 7 under the constraint that the sum of dimensions L17 and L16 is constant. The numerical simulations were performed in the same manner as in Embodiment 1 described above, based on a waveguide model.

[0078] Figure 14 is a graph showing the results of a numerical simulation regarding the radio wave transmission performance of a radio wave permeable material. As shown in Figure 14, it was shown that the frequency (wavelength) at which the radio wave transmission performance peaks shifts in accordance with the change in dimension L17, that is, it shifts in accordance with the diameter L16 of the annular conductive region 41C located on the inside. Note that dimension L17 is the distance between the outer circumference of the annular conductive region 41C and the inner circumference of the annular conductive region 41D in Figure 7. <Example 4>

[0079] In this embodiment, the change in radio wave transmission performance caused by forming a linear nonconductive pattern 420 on the conductive region 41 over the entire area of ​​the annular conductive regions 41C and 41D was evaluated. The pattern of the conductive region 41 defined in numerical simulation is shown in Figure 15. In the pattern of the conductive region 41 shown in Figure 15, the entire area of ​​the inner conductive region 41C and the entire area of ​​the outer conductive region 41D １ ,41D ２ In this configuration, a plurality of conductive patterns 410 and a plurality of non-conductive patterns 420 are formed alternately along the X-axis direction in the figure.

[0080] A radio wave transparent material having the conductive region 41 pattern shown in Figure 15 was designated as an embodiment of the present invention (Embodiment 4), and a numerical simulation of the radio wave transmission performance was performed for this Embodiment 4. The numerical simulation was performed in the same manner as in Embodiment 1 described above, based on a waveguide model. As a comparative example, a waveguide model was defined in which no conductive patterns 410 and no non-conductive patterns 420 were formed on the entire surface of the annular conductive regions 41C and 41D, and the radio wave intensity transmitted through the window material was calculated.

[0081] Figure 16 is a graph showing the results of a numerical simulation regarding the radio wave transmittance of a radio wave permeable material. In the figure, the waveform indicated by reference numeral 93 is the calculation result for the radio wave permeable material of the embodiment of the present invention, and the waveform indicated by reference numeral 97 is the calculation result for the radio wave permeable material of the comparative example. The vertical axis of the graph represents the radio wave transmittance to the metal layer 3 (Low-E film) provided in the window material 1 shown in Figure 1.

[0082] As shown in Figure 16, the radio wave permeable material according to the embodiment of the present invention was shown to have a higher peak in radio wave transmission performance at approximately 4.55 GHz, one of the practical target frequencies, compared to the peak of the comparative example.

[0083] 1 Window material 2 Transparent plate 21 First transparent plate 211 First surface 212 Second surface 22 Second transparent plate 221 First surface 222 Second surface 3 Metal layer 4 Radio wave permeable material (metasurface film) 40 Divided ring resonance section 400 Outer edge 410 Conductive pattern 420 Non-conductive pattern 422 (422C, 422D) Gap 41 (41C, 41D) Conductive layer (conductive region) 42 Non-conductive region 43 Substrate layer 44 Adhesive layer (second adhesive layer) 45 Protective film 46 Adhesive layer (first adhesive layer) 5 Spacer 6 Intermediate layer

Claims

1. A light-transmitting radio wave permeator disposed on the surface of a window material comprising at least one transparent plate and a metal layer laminated on the at least one transparent plate, comprising: a conductive layer and a substrate layer supporting the conductive layer, wherein the conductive layer is arranged periodically in multiple vertical and horizontal patterns, each having conductive regions and non-conductive regions surrounding the conductive regions, and in each of the patterns, a plurality of linear conductive patterns and a plurality of light-transmitting linear non-conductive patterns are alternately formed in the conductive regions along a first direction.

2. The radio wave transparent material according to claim 1, wherein the conductive region further has translucent linear nonconductive patterns formed at equal intervals along a direction intersecting the first direction.

3. The radio wave transparent material according to claim 1, wherein linear conductive patterns are further formed in the conductive region at equal intervals along a direction intersecting the first direction.

4. The radio wave transparent material according to claim 2, wherein the intersection angle is 90 degrees.

5. The radio wave transparent material according to claim 1, wherein the conductive region further has translucent linear nonconductive patterns formed at equal intervals along a plurality of directions intersecting the first direction.

6. The radio wave transparent material according to claim 1, wherein the non-conductive pattern is a gap between adjacent conductive patterns.

7. The radio wave transparent body according to claim 1, wherein the conductive region is circular, polygonal, or annular in plan view.

8. The radio wave permeable body according to claim 7, wherein the conductive region comprises a plurality of conductive regions arranged concentrically.

9. The radio wave permeable material according to claim 7, wherein the conductive region is annular, and at least one gap is provided in a part of the conductive region.

10. The radio wave transparent material according to claim 7, wherein the first direction is radial or circumferential.

11. A window material comprising: at least one transparent plate; a metal layer laminated on the at least one transparent plate; and a radio wave permeable material according to any one of claims 1 to 10, attached to the transparent plate or the metal layer.

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