Reflecting panel, electromagnetic wave reflecting device using same, electromagnetic wave reflecting fence and manufacturing method of reflecting panel

Abstract

Provided is a reflective panel in which at least one of the reflection efficiency and the accuracy of the reflection direction is improved. The reflective panel includes: a first substrate; a second substrate; and an intermediate layer that is provided between the first substrate and the second substrate and is formed by laminating a first intermediate film, a second intermediate film, and a third intermediate film in this order. The interface between the first intermediate film and the second intermediate film or the interface between the second intermediate film and the third intermediate film is a reflecting surface that reflects electromagnetic waves of 1 GHz to 300 GHz. If the average thickness of the first intermediate film is set as d1 and the average thickness of the third intermediate film is set as d2, the reflection panel satisfies 0.5 < d1 / d2 < 1.5.

Description

Technical Field

[0001] The invention relates to a reflection panel, an electromagnetic wave reflection device using the same, an electromagnetic wave reflection fence and a method for manufacturing the reflection panel. Background Art

[0002] It is expected that the fifth-generation mobile communication system (hereinafter referred to as "5G") will introduce high-speed, large-capacity, low-latency and large-scale simultaneously connected mobile communication technology into the communication network of IoT (Internet of Things) that processes large amounts of data. In addition to the mobility and flexibility inherent in mobile communication technology, the low latency characteristics of 5G are considered suitable for IoT. On the other hand, since 5G radio waves have high straightness, reflectors and the like are required to ensure the propagation path for sending radio waves to the required areas. If the introduction of the sixth-generation mobile communication system (referred to as "6G") using a higher frequency band is also taken into account, the reflection device used to improve the propagation environment requires the accuracy of reflection efficiency and reflection direction.

[0003] Patent Document 1: International Publication No. 2021 / 199504 Summary of the invention

[0004] In a reflective panel, there is a problem that the reflection direction and reflection efficiency deviate from the design, and radio waves cannot reach a desired area. One object of the present invention is to provide a reflective panel that improves at least one of the reflection efficiency and the accuracy of the reflection direction.

[0005] In one embodiment, the reflective panel comprises: a first substrate; a second substrate; and an intermediate layer, which is arranged between the first substrate and the second substrate and is formed by stacking a first intermediate film, a second intermediate film and a third intermediate film in sequence. The interface between the first intermediate film and the second intermediate film, or the interface between the second intermediate film and the third intermediate film is a reflective surface that reflects electromagnetic waves above 1 GHz and below 300 GHz. If the average thickness of the first intermediate film is set to d1 and the average thickness of the third intermediate film is set to d2, 0.5<d1 / d2<1.5 is satisfied.

[0006] A reflective panel having improved at least one of reflection efficiency and accuracy of reflection direction can be realized. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 This is a schematic diagram of an electromagnetic wave reflection fence formed by connecting electromagnetic wave reflection devices having reflection panels according to an embodiment.

[0008] Figure 2 It is along Figure 1 Horizontal section view taken along line A-A.

[0009] Figure 3 This is a diagram showing an example of the layer structure of the reflection panel.

[0010] Figure 4 It is a diagram showing another example of the layer structure of the reflection panel.

[0011] Figure 5A is a schematic diagram of the layer structure of the reflective panel of Example 1.

[0012] Figure 5B This is an optical microscope image of a cross section of the reflective panel of Example 1.

[0013] Fig. 6A It is a schematic diagram of the layer structure of the reflection panel of Example 5 which is a comparative example.

[0014] Figure 6B This is an optical microscope image of a cross section of the reflective panel of Example 5. DETAILED DESCRIPTION

[0015] Figure 1 The electromagnetic wave reflection fence 100 is a schematic diagram of an electromagnetic wave reflection device having a reflection panel according to an embodiment connected together. The electromagnetic wave reflection fence 100 is formed by connecting electromagnetic wave reflection devices 60-1, 60-2, and 60-3 having reflection panels 10-1, 10-2, and 10-3 (hereinafter collectively referred to as "reflection panels 10") in the horizontal direction. Figure 1 In the coordinate system, the width or horizontal direction of the reflective panel 10 is taken as the X direction, the height or vertical direction is taken as the Y direction, and the thickness direction is taken as the Z direction. Figure 1 In the embodiment, three electromagnetic wave reflecting devices 60 - 1 , 60 - 2 , and 60 - 3 (hereinafter collectively referred to as “electromagnetic wave reflecting devices 60 ” as appropriate) are connected to form the electromagnetic wave reflecting fence 100 , but the number of the connected electromagnetic wave reflecting devices 60 is not particularly limited.

[0016] The reflection panels 10-1, 10-2 and 10-3 used in the electromagnetic wave reflection devices 60-1, 60-2 and 60-3 reflect electromagnetic waves of a specified frequency band of 1 GHz to 300 GHz, for example, 1 GHz to 170 GHz, 1 GHz to 100 GHz, or 1 GHz to 80 GHz. As described later, each reflection panel 10 includes a layer forming a reflection surface. The reflection surface can be a mirror reflection surface with an equal incident angle and a reflection angle, or a metasurface that reflects the incident electromagnetic wave in a desired direction, or both.

[0017] Each electromagnetic wave reflecting device 60 has a frame 50 for holding the reflecting panel 10. The electromagnetic wave reflecting device 60 may also have a leg 56 for supporting the frame 50. The leg 56 is not essential, but in the example Figure 1 This is useful when the electromagnetic wave reflecting device 60 or the electromagnetic wave reflecting fence 100 is made to stand independently with respect to the installation surface (XZ surface).

[0018] When the reflection panels 10-1, 10-2, and 10-3 have mirror reflection surfaces, they are preferably electrically connected to each other from the viewpoint of maintaining the continuity of the reflection potential, but when a metasurface is included, the adjacent reflection panels 10 may not be electrically connected. By holding the adjacent reflection panels 10 with the frame 50, an electromagnetic wave reflection fence 100 connected in the X direction is obtained.

[0019] The electromagnetic wave reflecting device 60 may also include a top frame 57 for holding the upper end of the reflecting panel 10 and a bottom frame 58 for holding the lower end, in addition to the reflecting panel 10 and the frame 50. In this case, the frame 50, the top frame 57, and the bottom frame 58 constitute a frame for holding the entire circumference of the reflecting panel 10. According to the positional relationship relative to the top frame 57 and the bottom frame 58, the frame 50 may also be referred to as a "side frame". By providing the top frame 57 and the bottom frame 58, the mechanical strength and safety of the reflecting panel 10 during transportation and assembly can be ensured.

[0020] Figure 2 It is along Figure 1 Horizontal sectional view taken along line AA of the frame 50. The horizontal sectional view shows the reflective panels 10-1 and 10-2 held by the frame 50 through a section parallel to the XZ plane. The frame 50 has a conductive main body 500, and slits 51-1 and 51-2 formed on both sides of the main body 500 in the width direction. The edges of the reflective panels 10-1 and 10-2 are respectively inserted into the slits 51-1 and 51-2 and held in the space 52. The space 52 is not required, but by providing the space 52, the main body 500 of the frame 50 can be made lightweight and a margin can be provided for the holding angle of the reflective panel 10.

[0021] By inserting each of the reflection panels 10-1 and 10-2 into the slits 51-1 and 51-2, the adjacent reflection panels 10-1 and 10-2 can be stably held. A portion of the main body 500 may also be formed of a non-conductive material. A non-conductive cover 501 such as resin may also be provided on the outer surface of the main body 500, but the cover 501 is not required. When the cover 501 is provided, the cover 501 functions as a protective member for protecting the frame 50.

[0022] <Layer structure of reflective panel>

[0023] Figure 3An example of a layer structure of the reflective panel 10A is shown. The layer structure is a structure in the thickness (Z) direction of the reflective panel 10A. The reflective panel 10A includes: a first substrate 11; a second substrate 12; and an intermediate layer 13A disposed between the first substrate 11 and the second substrate 12. The intermediate layer 13A is stacked with a first intermediate film 131, a second intermediate film 132A, and a third intermediate film 133 in sequence. Depending on the incident direction of the electromagnetic wave, the interface between the first intermediate film 131 and the second intermediate film 132A, or the interface between the second intermediate film 132A and the third intermediate film 133 is a reflection surface that reflects electromagnetic waves in a specified frequency band of 1 GHz or more and 300 GHz or less.

[0024] The first substrate 11 and the second substrate 12 support the intermediate layer 13A from both sides. The first substrate 11 and the second substrate 12 are insulating polymer sheets or films such as polycarbonate, COP, polyethylene terephthalate (PET), and fluororesin. When the reflective panel 10A is used outdoors or in a production line, it is preferred to use polycarbonate with excellent impact resistance, durability, and transparency. In order to maintain the strength of the reflective panel 10A and reduce the total amount of the reflective panel 10A as much as possible, the thickness of the first substrate 11 and the second substrate 12 is appropriately selected within the range of 1.0 mm or more and 10.0 mm or less.

[0025] The second intermediate film 132A is formed of a material including metal, and reflects incident electromagnetic waves. As the material of the second intermediate film 132A, stainless steel, mild steel, copper, copper oxide, nickel, nickel oxide, gold, silver, aluminum, and a combination thereof can be used.

[0026] The first intermediate film 131 and the third intermediate film 133 are insulating resin films. As the resin, ethylene vinyl acetate, cycloolefin polymer (COP), ultraviolet curing resin, thermosetting resin, thermoplastic resin, etc. can be used. As the ultraviolet curing resin, polyurethane resin, acrylic resin, silicone resin, epoxy resin, polyurethane acrylate, etc. can be used. The materials of the first intermediate film 131 and the third intermediate film 133 can be the same or different. In order to be able to use the same reflection characteristics from any direction without distinguishing between the front and back sides of the reflection panel 10A, it is preferably formed of the same material.

[0027] The relative dielectric constant and dielectric loss tangent of the resin material of the first intermediate film 131 and the third intermediate film 133 are set in an appropriate range to suppress the reduction of reflection efficiency. The relative dielectric constant of the above-mentioned resin material is greater than 2.0 and less than 3.0, and the dielectric loss tangent is greater than 0.0001 and less than 0.1000. If the relative dielectric constant of the first intermediate film 131 and the third intermediate film 133 is greater than 3.0, the loss to high frequency may increase. Similarly, if the dielectric loss tangent of the first intermediate film 131 and the third intermediate film 133 is greater than 0.1000, the loss of electric energy in the resin film may increase.

[0028] If the average thickness of the first intermediate film 131 is set to d1, and the average thickness of the third intermediate film 133 is set to d2, then d1 and d2 satisfy 0.5<d1 / d2<1.5. Here, the average thickness refers to the thickness measured at 10 points in the width (X) direction of the reflection panel and averaged. This condition is the film thickness relationship of the intermediate layer 13A in the finished state. In the intermediate layer 13A of the manufactured electromagnetic wave reflection panel 10A, the average thickness of the first intermediate film 131 and the third intermediate film 133 satisfies this condition, and the position of the second intermediate film 132A in the intermediate layer 13A is stable, and at least one of the reflection efficiency and the reflection direction can be well maintained. If the difference in thickness between the first intermediate film 131 and the third intermediate film 133 is large, the second intermediate film 132A is too close to the surface of the intermediate layer 13A, and the coverage by the resin film becomes insufficient, and bubbles may be generated at the interface between the intermediate layer 13A and the first substrate 11 or the second substrate 12. Alternatively, the resin film may cover the second intermediate film 132A too thickly, which may cause undesirable bubbles to form inside the dielectric film.

[0029] By maintaining the average thickness d1 of the first intermediate film 131 and the average thickness d2 of the third intermediate film 133 in the range of 0.5<d1 / d2<1.5, the second intermediate film 132A can be stably maintained in the intermediate layer 13A, thereby suppressing the decrease in reflection efficiency or the degradation of the accuracy of the reflection direction. The value of d1 / d2 preferably satisfies 0.5<d1 / d2<1.5 and is substantially uniform throughout the entire periphery of the reflective panel 10.

[0030] The average thickness of the second intermediate film 132A is set to d3. From the perspective of being designed to be usable in the entire range of frequencies related to 5G or 6G and keeping the reflective panel 10 thin, in the finished state of the intermediate layer 13A, the total thickness of d1, d2, and d3, that is, the average thickness of the intermediate layer 13A is preferably less than the operating wavelength λ (d1+d2+d3<λ). For example, when the frequency of the electromagnetic wave incident on the reflective panel 10A is 28.0 GHz, the wavelength λ is 10.7 mm, and the thickness of the intermediate layer 13A is preferably thinner than 10.7 mm.

[0031] Figure 4 An example of the layer structure of the reflective panel 10B is shown. The reflective panel 10B has the same layer structure as the reflective panel 10A, except that the second intermediate film 132B of the intermediate layer 13B has an opening 135. The intermediate layer 13B is held between the first substrate 11 and the second substrate 12. The intermediate layer 13B is stacked with the first intermediate film 131, the second intermediate film 132B and the third intermediate film 133 in sequence. Depending on the incident direction of the electromagnetic wave, the interface between the first intermediate film 131 and the second intermediate film 132B, or the interface between the second intermediate film 132B and the third intermediate film 133 is a reflection surface that selectively reflects electromagnetic waves in a specified frequency band of more than 1 GHz and less than 300 GHz. The materials, thickness, etc. of the first substrate 11, the second substrate 12, the first intermediate film 131 and the third intermediate film 133 are the same as those of the reflective panel 10A.

[0032] The opening 135 of the second intermediate film 132B may be a through hole in a square, circular, elliptical, polygonal or the like, or may be a grid opening. The opening 135 penetrating the second intermediate film 132B may also be formed in a periodic arrangement to improve the selectivity of reflection of a specific frequency. The second intermediate film 132B may also be formed into a grid structure, and the grid openings may be used as the openings 135 of the second intermediate film 132B. From the perspective of maintaining the reflection efficiency and maintaining the high visible light transmittance of the reflective panel 10B, the opening ratio of the second intermediate film 132B is preferably 50% or more and 80% or less. If the opening ratio exceeds 80%, the desired reflection efficiency may not be obtained. If the opening ratio is less than 50%, the visible light transmittance of the reflective panel 10B may decrease. Depending on the usage form of the reflective panel 10B, when transparency to visible light is not required, the opening ratio of the opening 135 may be made less than 50% to give priority to improving the reflection efficiency.

[0033] The first intermediate film 131 and the third intermediate film 133 may also be connected in the opening 135 of the second intermediate film 132B. The opening 135 does not need to be completely filled with the resin film, and may be 90.0% or more of the total area or total volume of the opening 135 depending on the lamination conditions when forming the intermediate layer 13B. The first intermediate film 131 and the third intermediate film 133 may enter the opening 135 from both sides of the second intermediate film 132B, or any one of the first intermediate film 131 and the third intermediate film 133 may enter the opening 135.

[0034] For the intermediate layer 13B, in the finished product state, the average thickness d1 of the first intermediate film 131 and the average thickness d2 of the third intermediate film 133 also satisfy the condition of 0.5<d1 / d2<1.5. As a result, the second intermediate film 132B can be stably maintained in the intermediate layer 13B, and the decrease in reflection efficiency or the deterioration in the accuracy of the reflection direction can be suppressed. In addition, the average thickness of the second intermediate film 132B is set to d3, and the total thickness of d1, d2, and d3, that is, the thickness of the intermediate layer 13B is less than the operating wavelength λ (d1+d2+d3<λ).

[0035] Hereinafter, by making samples under different conditions and measuring the reflection attenuation at a specified frequency, the preferred range of the film thickness relationship of the first intermediate film 131, the second intermediate film, and the third intermediate film included in the intermediate layer 13 is verified. The reflection attenuation is measured using a vector network analyzer and a high-frequency oblique-incidence free-space S parameter measurement fixture. As a reference value for the reflection attenuation, a smooth aluminum plate with a thickness of 3 mm and a size of 300 mm × 300 mm is used to measure the reflection attenuation, and the measured value is set to 0.00 dB for the reflection attenuation.

[0036] [Example 1]

[0037] Example 1 is Example 1. A sample of a reflective panel 10 was prepared using a polycarbonate sheet of 2 mm thickness as the first substrate 11 and the second substrate 12 and an intermediate layer 13 disposed between the two polycarbonate sheets. As the design conditions of the intermediate layer 13, the first intermediate film 131 used ethylene vinyl acetate with a thickness of 400 μm, the second intermediate film 132 used a stainless steel mesh with a thickness of 100 μm, and the third intermediate film 133 used ethylene vinyl acetate with a thickness of 400 μm. The average opening diameter of the stainless steel mesh was 268 μm, and the average opening ratio was 71%. The reflective panel 10 was prepared by sandwiching the laminate with two glasses of 3 mm thickness and heating them at 130° C. for 60 minutes under vacuum. The size of the reflective panel 10 was 1000 mm×2000 mm.

[0038] Figure 5A A schematic diagram of the layer structure of the reflective panel of Example 1 is shown in FIG. Figure 5B The optical microscopic image of the sample cross section is shown in FIG. In the finished product state of the sample of Example 1, the average thickness d1 of the first intermediate film 131 is 400 μm, the average thickness d3 of the second intermediate film 132 is 100 μm, and the average thickness d2 of the third intermediate film 133 is 400 μm. d1 / d2=1.0, which satisfies the condition of 0.5<d1 / d2<1.5. In addition, d1+d2+d3=900 μm. Figure 5BAs shown, when observing the finished appearance of the sample, no bubbles were generated within the effective range of 1000mm×2000mm, and the position of the second intermediate film 132 in the intermediate layer 13 was roughly uniform. When the reflection attenuation was measured for the incident electromagnetic wave of 28.0GHz, compared with the ideal aluminum plate reflector, it was -0.02dB, and the reflection attenuation was very small. The wavelength λ at 28GHz is 10.7mm, so it also meets the condition of d1+d2+d3<λ. The reflection characteristics of the sample made in Example 1 are good.

[0039] [Example 2]

[0040] Example 2 is Example 2. A sample of a reflective panel 10 is prepared using a polycarbonate sheet with a thickness of 2 mm as the first substrate 11 and the second substrate 12 and an intermediate layer 13 is arranged between the two polycarbonate sheets. The design conditions of the intermediate layer 13 are the same as those of Example 1, the first intermediate film 131 is ethylene vinyl acetate with a thickness of 400 μm, the second intermediate film 132 is a stainless steel mesh with a thickness of 100 μm, and the third intermediate film 133 is ethylene vinyl acetate with a thickness of 400 μm. The conditions of the stainless steel mesh are also the same. In the bonding process, the above-mentioned laminate is sandwiched between two glasses with a thickness of 3 mm, and heated at 90°C for 60 minutes under vacuum to prepare a sample of Example 2. The size of the reflective panel 10 is 1000 mm×2000 mm.

[0041] In the finished product state of the sample, the average thickness d1 of the first intermediate film 131 is 400μm, the average thickness d3 of the second intermediate film 132 is 100μm, and the average thickness d2 of the third intermediate film 133 is 350μm. d1 / d2=1.1, which satisfies the condition of 0.5<d1 / d2<1.5. In addition, d1+d2+d3=850μm, which also satisfies the condition of d1+d2+d3<λ. When observing the finished product appearance of the sample, no bubbles were generated within the effective range of 1000mm×2000mm. When the reflection attenuation was measured for an incident electromagnetic wave of 28.0GHz, it was -0.03dB compared with the ideal aluminum plate reflector, confirming that the reflection attenuation was very small.

[0042] [Example 3]

[0043] Example 3 is Example 3. A sample of a reflective panel 10 is prepared using a polycarbonate sheet with a thickness of 2 mm as the first substrate 11 and the second substrate 12 and an intermediate layer 13 is arranged between the two polycarbonate sheets. The design conditions of the intermediate layer 13 are the same as those of Example 1, the first intermediate film 131 is ethylene vinyl acetate with a thickness of 400 μm, the second intermediate film 132 is a stainless steel mesh with a thickness of 100 μm, and the third intermediate film 133 is ethylene vinyl acetate with a thickness of 400 μm. The conditions of the stainless steel mesh are also the same. In the bonding process, the above-mentioned laminate is sandwiched between two glasses with a thickness of 3 mm, and heated at 88°C for 60 minutes under vacuum to prepare a sample of Example 2. The size of the reflective panel 10 is 1000 mm×2000 mm.

[0044] In the finished product state of the sample, the average thickness d1 of the first intermediate film 131 is 400μm, the average thickness d3 of the second intermediate film 132 is 100μm, and the average thickness d2 of the third intermediate film 133 is 285μm. d1 / d2=1.4, which satisfies the condition of 0.5<d1 / d2<1.5. In addition, d1+d2+d3=785μm, which also satisfies the condition of d1+d2+d3<λ. When observing the finished product appearance of the sample, no bubbles were generated within the effective range of 1000mm×2000mm. When the reflection attenuation was measured for an incident electromagnetic wave of 28.0GHz, it was -0.20dB compared with the ideal aluminum plate reflector, confirming that the reflection attenuation was reduced.

[0045] [Example 4]

[0046] Example 4 is Comparative Example 1. The design conditions are the same as those of Examples 1 to 3. That is, a sample of a reflective panel 10 is prepared using a polycarbonate sheet with a thickness of 2 mm as the first substrate 11 and the second substrate 12 and an intermediate layer 13 is arranged between the two polycarbonate sheets. For the design value of the intermediate layer 13, the first intermediate film 131 is ethylene vinyl acetate with a thickness of 400 μm, the second intermediate film 132 is a stainless steel mesh with a thickness of 100 μm, and the third intermediate film 133 is ethylene vinyl acetate with a thickness of 400 μm. The conditions of the stainless steel mesh are also the same. In the bonding process, the above-mentioned laminate is sandwiched between two glasses with a thickness of 3 mm, and heated at 80°C for 60 minutes under vacuum to prepare a sample of Example 3. The size of the reflective panel 10 is 1000 mm×2000 mm.

[0047] In the finished product state of the sample, the average thickness d1 of the first intermediate film 131 is 400μm, the average thickness d3 of the second intermediate film 132 is 100μm, and the average thickness d2 of the third intermediate film 133 is 200μm. d1 / d2=2.0, which is outside the range of 0.5<d1 / d2<1.5. When the cross-section of the sample of Example 4 was observed with an optical microscope, 25 bubbles ranging in size from 2mm to 10mm were observed within the effective range of 1000mm×2000mm. When the reflection attenuation was measured for an incident electromagnetic wave of 28.0GHz, it was -1.75dB compared with the ideal aluminum plate reflector, indicating that the reflection attenuation increased. This is believed to be because the position of the second intermediate film 132 in the intermediate layer 13 was offset, and bubbles were generated in the resin film as a result.

[0048] [Example 5]

[0049] Example 5 is Comparative Example 2. The design conditions are the same as those of Examples 1 to 4 except for the second intermediate film 132. A sample of a reflective panel 10 is prepared using a polycarbonate sheet with a thickness of 2 mm as the first substrate 11 and the second substrate 12 and an intermediate layer 13 is arranged between the two polycarbonate sheets. The first intermediate film 131 and the third intermediate film of the intermediate layer 13 are ethylene vinyl acetate with a thickness of 400 μm. As the second intermediate film 132, a film formed by forming a sputtered film of a Ag-based metal with a thickness of 360 nm on polyethylene terephthalate with a thickness of 100 μm is used. The above-mentioned laminate is sandwiched between two glasses with a thickness of 3 mm and heated at 130° C. for 60 minutes under vacuum to prepare a sample of Example 4. The size of the reflective panel 10 is 1000 mm×2000 mm.

[0050] Fig. 6A A schematic diagram of the layer structure of the reflective panel of Example 5 is shown in FIG. Figure 6B The optical microscopic image of the sample cross section is shown in FIG. In the finished product state of the sample of Example 5, the average thickness d1 of the first intermediate film 131 is 400 μm, and the average thickness d2 of the third intermediate film 133 is 50 μm. d1 / d2=8.0, which is outside the range of 0.5<d1 / d2<1.5. Figure 6B As shown in the figure, when observing the finished product appearance of the sample, 125 bubbles 101 of about 2mm to 10mm in size were observed within the effective range of 1000mm×2000mm. When the reflection attenuation was measured for the incident electromagnetic wave of 28.0GHz, it was -2.20dB compared with the ideal aluminum plate reflector, indicating that the reflection attenuation increased. This is believed to be because the position of the second intermediate film 132 in the intermediate layer 13 was significantly offset, and with this, a large number of bubbles 101 were generated in the resin film, and the relative dielectric constant of the first intermediate film 131 deviated from the design value.

[0051] In this way, in the finished state of the intermediate layer of the three-layer structure in which the second intermediate film 132 is sandwiched by the first intermediate film 131 and the third intermediate film 133, the average thickness d1 of the first intermediate film 131 and the average thickness d2 of the third intermediate film 133 satisfy 0.5<d1 / d2<1.5. Even if the first intermediate film 131 and the third intermediate film 133 are reversed, the film thickness relationship of d1 and d2 is the same, so d1 / d2 is less than 1.5 when viewed from the opposite side, which means that d1 / d2 is greater than 0.5. The manufacturing method of the reflective panel 10 is

[0052] (a) an intermediate layer 13 including a first intermediate film 131 , a second intermediate film 132 , and a third intermediate film 133 stacked in this order is disposed between the first substrate 11 and the second substrate 12 ;

[0053] (b) The first substrate 11, the intermediate layer 13 and the second substrate 12 are vacuum pressed together at a temperature higher than 80°C and lower than 130°C, so that the ratio d1 / d2 of the average thickness d1 of the first intermediate film 131 to the average thickness d2 of the third intermediate film 133 after pressing satisfies 0.5<d1 / d2<1.5.

[0054] This can reduce the reflection loss and suppress the reduction of reflection efficiency. It can suppress the generation of bubbles 101 inside the first intermediate film 131 or the third intermediate film 133 and suppress the deviation of the reflection direction from the designed direction due to the change of the refractive index or relative dielectric constant.

[0055] It is preferred that the condition of d1+d2+d3<λ is satisfied on the premise that the first intermediate film 131 and the third intermediate film 133 satisfy the condition of 0.5<d1 / d2<1.5. Even if d1+d2+d3<λ is satisfied, if it deviates from the range of 0.5<d1 / d2<1.5, the reflection attenuation amount becomes large, and it is difficult to maintain the reflection efficiency or the accuracy of the reflection direction.

[0056] By using the above-mentioned reflection panel 10 in the electromagnetic wave reflection device 60 and the electromagnetic wave reflection fence 100, the reflection attenuation can be reduced, and at least one of the reflection efficiency and the accuracy of the reflection direction can be maintained. The electromagnetic wave reflection device and the electromagnetic wave reflection fence using the reflection panel of the embodiment can be effectively used in an environment where a large number of blind spots are generated in a limited space. In the case where the reflection panel 10 has transparency to visible light, the electromagnetic wave reflection device and the electromagnetic wave reflection fence can also be used as a safety fence or a soundproof fence.

[0057] The in-plane dimensions of the reflective panel 10 can be appropriately selected within the range of 30 cm × 30 cm to 3 m × 3 m. The entire surface of the reflective panel 10 can be a super surface, or a portion can be a mirror reflective surface. By providing a protective layer such as an ultraviolet protection film on the surfaces of the first substrate 11 and the second substrate of the reflective panel 10, it can be used for a long time in an outdoor environment.

[0058] As mentioned above, although embodiment of this disclosure was described, this disclosure can include the following structures.

[0059] (Item 1)

[0060] A reflective panel, wherein

[0061] have:

[0062] a first substrate;

[0063] a second substrate; and

[0064] The intermediate layer is disposed between the first substrate and the second substrate and is formed by sequentially stacking a first intermediate film, a second intermediate film and a third intermediate film.

[0065] The interface between the first intermediate film and the second intermediate film, or the interface between the second intermediate film and the third intermediate film, is a reflection surface that reflects electromagnetic waves of 1 GHz or more and 300 GHz or less.

[0066] When the average thickness of the first intermediate film is d1 and the average thickness of the third intermediate film is d2, 0.5<d1 / d2<1.5 is satisfied.

[0067] (Item 2)

[0068] The reflective panel according to item 1, wherein:

[0069] The thickness of the intermediate layer is smaller than the wavelength of the electromagnetic wave incident on the reflecting surface.

[0070] (Item 3)

[0071] A reflective panel according to item 1 or 2, wherein:

[0072] The first intermediate film and the third intermediate film are resin layers.

[0073] (Item 4)

[0074] The reflective panel according to item 3, wherein:

[0075] The resin layer has a relative dielectric constant of 2.0 or more and 3.0 or less, and a dielectric loss tangent of 0.0001 or more and less than 0.1000.

[0076] (Item 5)

[0077] The reflective panel according to any one of items 1 to 4, wherein:

[0078] The second intermediate film is a film containing metal.

[0079] (Item 6)

[0080] The reflective panel according to item 5, wherein:

[0081] The second intermediate film has through holes or openings of a mesh structure.

[0082] (Item 7)

[0083] The reflective panel according to item 6, wherein:

[0084] The opening ratio of the through holes or the mesh structure is 50.0% or more and 80% or less.

[0085] (Item 8)

[0086] A reflective panel according to item 6 or 7, wherein:

[0087] The first intermediate film and the third intermediate film are connected inside the opening.

[0088] (Item 9)

[0089] The reflective panel according to any one of items 6 to 8, wherein:

[0090] At least one of the first intermediate film and the third intermediate film enters the opening.

[0091] (Item 10)

[0092] A reflective panel according to item 9, wherein:

[0093] The filling rate of the openings is 90.0% or more of the total area or volume of the openings.

[0094] (Item 11)

[0095] An electromagnetic wave reflecting device, wherein:

[0096] have:

[0097] The reflective panel according to any one of items 1 to 10; and

[0098] A frame holds the above-mentioned reflective panel.

[0099] (Item 12)

[0100] An electromagnetic wave reflecting fence, wherein:

[0101] The electromagnetic wave reflecting device described in item 11 has two or more of them, wherein two or more of the reflecting panels are connected via the frame.

[0102] (Item 13)

[0103] A method for manufacturing a reflective panel, wherein:

[0104] An intermediate layer formed by sequentially stacking a first intermediate film, a second intermediate film, and a third intermediate film is disposed between the first substrate and the second substrate.

[0105] The first substrate, the intermediate layer and the second substrate are vacuum pressed at a temperature higher than 80°C and lower than 130°C, so that the ratio d1 / d2 of the average thickness d1 of the first intermediate film to the average thickness d2 of the third intermediate film after pressing satisfies 0.5<d1 / d2<1.5.

[0106] This application claims priority based on Japanese Patent Application No. 2022-152154 filed on September 26, 2022, and includes the entire contents of the Japanese patent application.

[0107] Description of Reference Numerals

[0108] 10, 10-1, 10-2, 10-3, 10A, 10B…reflection panel; 11…first substrate; 12…second substrate; 13, 13A, 13B…middle layer; 50…frame (side frame); 57…top frame; 58…bottom frame; 60, 60-1, 60-2, 60-3…electromagnetic wave reflecting device; 100…electromagnetic wave reflecting fence; 101…bubble; 131…first intermediate film; 132…second intermediate film; 133…third intermediate film; 135…opening; d1…average thickness of the first intermediate film; d2…average thickness of the third intermediate film.

Claims

1. A reflective panel, characterized in that: have: a first substrate; a second substrate; as well as The intermediate layer is disposed between the first substrate and the second substrate and is formed by sequentially stacking a first intermediate film, a second intermediate film, and a third intermediate film. The interface between the first intermediate film and the second intermediate film, or the interface between the second intermediate film and the third intermediate film, is a reflection surface that reflects electromagnetic waves of 1 GHz or more and 300 GHz or less. If the average thickness of the first intermediate film is d1 and the average thickness of the third intermediate film is d2, 0.5<d1 / d2<1.5 is satisfied.

2. The reflective panel according to claim 1, characterized in that: The thickness of the intermediate layer is smaller than the wavelength of the electromagnetic wave incident on the reflecting surface.

3. The reflective panel according to claim 1, characterized in that: The first intermediate film and the third intermediate film are resin layers.

4. The reflective panel according to claim 3, characterized in that: The resin layer has a relative dielectric constant of 2.0 or more and 3.0 or less, and a dielectric loss tangent of 0.0001 or more and less than 0.1000.

5. The reflective panel according to claim 1, characterized in that: The second intermediate film is a film containing metal.

6. The reflective panel according to claim 5, characterized in that: The second intermediate film has through holes or openings in a mesh structure.

7. The reflective panel according to claim 6, characterized in that: The opening ratio of the through holes or the mesh structure is 50.0% or more and 80% or less.

8. The reflective panel according to claim 6, characterized in that: The first intermediate film and the third intermediate film are connected inside the opening.

9. The reflective panel according to claim 6, characterized in that: At least one of the first intermediate film and the third intermediate film enters the interior of the opening.

10. The reflective panel according to claim 9, characterized in that: The filling rate of the openings is 90.0% or more of the total area or volume of the openings.

11. An electromagnetic wave reflection device, characterized in that: have: The reflective panel according to any one of claims 1 to 10; and A frame holds the reflective panel.

12. An electromagnetic wave reflecting fence, characterized in that: The electromagnetic wave reflecting device according to claim 11 comprises two or more of the reflecting panels connected to each other via the frame.

13. A method for manufacturing a reflective panel, characterized in that: An intermediate layer formed by sequentially stacking a first intermediate film, a second intermediate film, and a third intermediate film is disposed between the first substrate and the second substrate. The first substrate, the intermediate layer and the second substrate are vacuum pressed at a temperature higher than 80°C and lower than 130°C, so that the ratio d1 / d2 of the average thickness d1 of the first intermediate film to the average thickness d2 of the third intermediate film after pressing satisfies 0.5<d1 / d2<1.5.

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