Electromagnetic wave shield

Abstract

An electromagnetic wave shield (1) comprises: a sheet-shaped insulator (2) having a first surface (3); and a first cell (11) provided on the first surface (3) of the insulator (2) and formed from a metal thin wire (13). The first cell (11) has: a plurality of vertices (20) that are provided at positions that form a regular polygon when linearly connected to each other, and that include a first point (21) and a second point (22); and a first line (30) that connects the first point (21) and the second point (22) and intersects a straight line (VL) that connects the first point (21) and the second point (22). The first line (30) is a curved line.

Description

Electromagnetic wave shielding

[0001] The present invention relates to an electromagnetic wave shield.

[0002] BACKGROUND ART Conventionally, techniques (sheets as conductive films) disclosed in, for example, Patent Documents 1 and 2 are known for electromagnetic wave shielding.

[0003] JP 2023-84147 A JP 2016-85037 A

[0004] 7, 8(A), 8(B), and 8(C) of Patent Document 1 disclose a configuration having rectangular, triangular, or hexagonal cells. In such a configuration, the thin metal wires forming the cells are linear. Therefore, when electromagnetic waves incident on an electromagnetic shield strike a linear thin metal wire, the reflected waves are diffused only in a certain direction. In other words, even if the incident electromagnetic waves strike a linear thin metal wire, the reflected waves do not diffuse in all directions. Therefore, noise caused by reflected waves cannot be sufficiently diffused around the electromagnetic shield.

[0005] Furthermore, for example, FIG. 8(D) of Patent Document 1 discloses a configuration that combines a pentagonal cell and a diamond-shaped cell (a cell surrounded by four pentagonal cells). Since this configuration includes cells that do not form a regular polygon (diamond-shaped cells), it is not isotropic as a whole. In other words, the configuration disclosed in FIG. 8(D) of Patent Document 1 is anisotropic as a whole. Therefore, with the configuration disclosed in FIG. 8(D) of Patent Document 1, the reflected wave does not diffuse isotropically, and noise caused by the reflected wave cannot be sufficiently diffused around the electromagnetic wave shield.

[0006] Furthermore, for example, Figure 8(E) of Patent Document 1 discloses a configuration that combines a circular cell and a substantially triangular cell surrounded by three circular cells. Even with this configuration, the configuration does not have isotropy as a whole because it includes cells that do not form a regular polygon (substantially triangular cells that are not equilateral triangles). Therefore, even with the configuration disclosed in Figure 8(E) of Patent Document 1, reflected waves do not diffuse isotropically, and noise caused by reflected waves cannot be sufficiently diffused around the electromagnetic wave shield.

[0007] Furthermore, in Patent Document 2, thin metal wires of a predetermined shape are arranged in cells based on a non-regular polygonal rhombus. However, the configuration of Patent Document 2 is based on cells that do not form a regular polygon (rhombus-shaped cells), and therefore does not have isotropy as a whole. That is, in the configuration of Patent Document 2, the thin metal wires are anisotropically arranged in the rhombus-shaped cells. As a result, when electromagnetic waves incident on a sheet having the configuration of Patent Document 2 hit the thin metal wires, the reflected waves are anisotropically diffused. This may result in a localized decrease in the diffusion degree of noise caused by the electromagnetic waves at the destination of the reflected waves. In such cases, noise caused by the reflected waves cannot be sufficiently diffused around the electromagnetic wave shield.

[0008] The present disclosure has been made in view of the above points, and its purpose is to diffuse noise caused by reflected waves.

[0009] To achieve the above object, one embodiment of the present disclosure is an electromagnetic wave shield including a sheet-like insulator having a first surface, and first cells formed on the first surface of the insulator and made of thin metal wires. The first cells are arranged at positions that form a regular polygon when connected to each other by straight lines, and have a plurality of vertices including a first point and a second point, and a first line that connects the first point and the second point and intersects with the line connecting the first point and the second point, the first line being a curve.

[0010] According to the present disclosure, noise caused by reflected waves can be diffused.

[0011] FIG. 1 is a schematic diagram illustrating an electromagnetic wave shield according to an embodiment of the present disclosure provided on a windowpane of a building. FIG. 2 is a partially enlarged view of section II shown in FIG. 1. FIG. 3 is a cross-sectional view taken along line III-III in FIG. 2. FIG. 4 is a partially enlarged view illustrating only the first cell shown in FIG. 2. FIG. 5 is a partially enlarged view of section V shown in FIG. 4. FIG. 6 is a graph illustrating the relationship between the frequency (unit: GHz) of an electromagnetic wave and the shielding performance (unit: dB) of each sample when a predetermined electromagnetic wave is incident on each of four samples having different pitch values. FIG. 7 is a partially enlarged view of a portion of an electromagnetic wave shield having a lattice-shaped cell configuration according to the prior art. FIG. 8 is a schematic illustration of a wave reflected upward from the top surface of the electromagnetic wave shield when a predetermined electromagnetic wave is irradiated onto the configuration of the prior art (see FIG. 7). FIG. 9 is a schematic illustration of a wave reflected upward from the first surface when a predetermined electromagnetic wave is irradiated onto an electromagnetic wave shield according to an embodiment of the present disclosure. Fig. 10 is a diagram schematically illustrating visible light incident from above onto the top surface of an electromagnetic shield according to a conventional configuration, and then transmitted downward from the bottom surface of the electromagnetic shield. Fig. 11 is a diagram illustrating diffracted light projected onto a screen after passing through a 632.8 nm laser diode in the conventional configuration (electromagnetic shield composed of lattice cells) shown in Fig. 7 . Fig. 12 is a diagram schematically illustrating visible light incident from above onto the top surface of an electromagnetic shield according to an embodiment of the present disclosure, and then transmitted downward from the bottom surface of the electromagnetic shield. Fig. 13 is a diagram illustrating diffracted light projected onto a screen after passing through a 632.8 nm laser diode in an electromagnetic shield according to an embodiment of the present disclosure. Fig. 14 is a graph illustrating the relationship between the light intensity (unit: a.u.) of the first harmonic and the width of the first-order diffracted light (horizontal axis / unit: a.u.) for light transmitted through an electromagnetic shield according to a conventional configuration and an electromagnetic shield according to an embodiment of the present disclosure. FIG. 15 is a schematic diagram in which incident light IL and transmitted light TL1 are superimposed on the cross-sectional view taken along line XV-XV in FIG. 7 in the configuration of the prior art.Fig. 16 is a schematic diagram of an electromagnetic wave shield according to an embodiment of the present disclosure, in which incident light IL and transmitted light TL2 are superimposed on the cross-sectional view taken along line XVI-XVI in Fig. 4. Fig. 17 is a diagram equivalent to Fig. 2, illustrating a modified example of an electromagnetic wave shield according to an embodiment of the present disclosure, in which the first line is a sine curve. Fig. 18 is a partially enlarged view showing only the first cell shown in Fig. 17. Fig. 19 is a partially enlarged view of portion XIX shown in Fig. 18.

[0012] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. The following description of the embodiments is merely exemplary in nature and is not intended to limit the present disclosure, its applications, or its uses.

[0013] Fig. 1 schematically illustrates an electromagnetic wave shield 1 (see Fig. 2) according to an embodiment of the present disclosure provided on a window glass G (a glass surface on the outside of the building B) of a building B. Fig. 2 illustrates an enlarged view of a portion of the electromagnetic wave shield 1 provided on the window glass G.

[0014] The electromagnetic wave shield 1 can be attached to the window glass G via, for example, an optical clear adhesive (OCA) (not shown). This allows the electromagnetic wave shield 1 to reflect electromagnetic waves incident on the window glass G (hereinafter sometimes referred to as "incident waves").

[0015] The electromagnetic wave shield 1 has a total light transmittance (see JIS K 7375-2008) of 70% or more. Preferably, the electromagnetic wave shield 1 has a total light transmittance of 80%. The electromagnetic wave shield 1 also has a sheet resistance of 0.1 Ω / □ or more and 5.0 Ω / □ or less.

[0016] 2 and 3, the electromagnetic wave shield 1 includes an insulator 2. The insulator 2 is transparent.

[0017] The insulator 2 is formed in a sheet shape and has a thickness of, for example, 25 μm or more and 200 μm or less.

[0018] 3, the insulator 2 has a first surface 3. The first surface 3 in this embodiment is the top surface of the insulator 2.

[0019] As shown in FIG. 3, the insulator 2 has a first layer 4 and a second layer 5 .

[0020] The first layer 4 is made of a transparent resin material, such as PET (polyethylene terephthalate), PEN (polyethylene naphthalate), PC (polycarbonate), COP (cycloolefin polymer), COC (cycloolefin copolymer), and PMMA (polymethyl methacrylate).

[0021] The second layer 5 is laminated on the upper side of the first layer 4. The second layer 5 is made of an insulating and transparent resin material. The thickness of the second layer 5 is greater than the depth of the groove portion 6 (described later). The upper surface of the second layer 5 corresponds to the first surface 3.

[0022] (Groove Portions) As shown in Fig. 3, a plurality of groove portions 6 are provided on the upper surface (first surface 3) of the insulator 2. The groove portions 6 have a bottom that is recessed from the first surface 3 toward the thickness direction of the second layer 5. The aspect ratio of the groove portions 6 (the value obtained by dividing the depth dimension Ld shown in Fig. 3 by the groove width dimension Lw) is 0.3 or more. The depth dimension Ld of the groove portions 6 is set to, for example, 0.7 µm or more and 4.0 µm or less.

[0023] (Cells) As shown in Fig. 2, the electromagnetic wave shield 1 includes a plurality of cells 10. Each cell 10 is formed of thin metal wires 13. Each cell 10 is formed in a closed shape by the thin metal wires 13. The basic shape of the cells 10 is a regular polygon (see Fig. 4). Specifically, in this embodiment, a regular hexagon is exemplified as the regular polygon.

[0024] In this embodiment, for convenience of explanation, any one of the cells 10 will be referred to as a "first cell 11." Also, the cell 10 adjacent to the first cell 11 (the cell 10 located at the upper right of the first cell 11 in FIG. 2 ) will be referred to as a "second cell 12."

[0025] The first cells 11 are provided on the first surface 3 of the insulator 2 (see FIGS. 2 and 3). The first cells 11 are formed of thin metal wires 13. The line width of the thin metal wires 13 forming the first cells 11 (the groove width dimension Lw shown in FIG. 3) is 1.0 μm or more and 3.0 μm or less.

[0026] The second cells 12 are provided on the first surface 3 of the insulator 2 (see FIGS. 2 and 3). The second cells 12 are formed of thin metal wires 13. The line width of the thin metal wires 13 forming the second cells 12 is 1.0 μm or more and 3.0 μm or less.

[0027] 2 indicates the center of gravity of the first cell 11. The reference symbol Cg2 shown in FIG.

[0028] 3, the thin metal wires 13 include a conductive metal embedded in the grooves 6. This configuration facilitates the formation of curved first lines 30 (described later). The thin metal wires 13 are composed of an adhesion layer 14, a seed layer 15, a conductive layer 16, and a blackening layer 17.

[0029] The adhesion layer 14 is an element for ensuring adhesion of the seed layer 15 to the groove portion 6. The adhesion layer 14 is, for example, a metal layer composed of a metal nitride or metal oxide containing at least one metal selected from the group consisting of Ti, Ni, Al, V, W, Ta, Si, Cr, Ag, Mo, Cu, and Zn. The adhesion layer 14 may be a single layer or a laminate in which multiple layers with different compositions are stacked. The adhesion layer 14 is stacked in the form of a thin film on the groove portion 6 by, for example, vapor deposition or sputtering.

[0030] The seed layer 15 has a function of bonding the conductive layer 16 to the adhesion layer 14. Specifically, the seed layer 15 functions as a cathode for depositing a plating solution containing copper (Cu) or the like, which will be described later, on the adhesion layer 14 in this embodiment, for example, during an electroplating process for forming the conductive layer 16. The seed layer 15 is deposited as a thin film on the adhesion layer 14 by, for example, vapor deposition or sputtering.

[0031] The conductive layer 16 is made of a conductive metal such as copper (Cu). The conductive layer 16 is formed, for example, by electroplating. When the electroplating is performed, the seed layer 15 and the conductive layer 16 are formed integrally. This makes it impossible to distinguish the interface between the seed layer 15 and the conductive layer 16. Note that although copper (Cu) is suitable as the main component of the plating solution used in the electroplating, metals other than copper (e.g., silver, gold) may also be included.

[0032] The blackened layer 17 has a function of making the thin metal wires 13 invisible when viewed from the first surface 3 of the insulator 2. The blackened layer 17 is laminated on the surface of the conductive layer 16. The blackened layer 17 is formed by substituting palladium for copper crystal grains located at the boundaries between copper crystal grains located on the surface of the conductive layer 16 (blackening treatment). The thickness of the blackened layer 17 is, for example, 7 nm or more and 10 nm or less.

[0033] (Vertices) As shown in Fig. 4 , the first cell 11 has a plurality of vertices 20. The plurality of vertices 20 are provided at positions that form a regular polygon when connected to one another by straight lines VL. All of the plurality of vertices 20 are located on the first surface 3 of the insulator 2. Furthermore, each vertex 20 is located at an intersection of the thin metal wires 13, 13 that form the cell 10.

[0034] The straight line VL corresponds to the imaginary line shown in Figures 2 and 4. That is, the straight line VL is not formed by the thin metal wires 13.

[0035] As described above, in this embodiment, a regular hexagon is exemplified as the "regular polygon" that serves as the base of the first cell 11 (cell 10). The multiple vertices 20 that form the regular hexagon of the first cell 11 are the six vertices 20 shown in FIG.

[0036] In this embodiment, for convenience of explanation, any one of the multiple vertices 20 will be referred to as a "first point 21." Also, the vertex 20 located diagonally below the first point 21 on the paper surface in Fig. 4 will be referred to as a "second point 22." Furthermore, the vertex 20 located diagonally below the first point 21 on the paper surface in Fig. 4 will be referred to as a "third point 23."

[0037] 4 and 5 , the first cell 11 includes a first point 21 and a second point 22. The first cell 11 further includes a third point 23. The third point 23 is located at a position obtained by rotating the second point 22 by 120 degrees around the first point 21. Specifically, the third point 23 is located at a position obtained by rotating the second point 22 by 120 degrees counterclockwise around the first point 21.

[0038] The first cell 11, which is based on a regular hexagon, is isotropic. That is, the curved first wires 30 (thin metal wires 13) can be isotropically arranged on each side of the first cell 11, which is based on a regular hexagon. As a result, when electromagnetic waves (incident waves) incident on the electromagnetic wave shield 1 hit the first wires 30, the reflected waves are diffused isotropically in all directions. Therefore, the degree of diffusion of noise caused by the electromagnetic waves increases in the destination of the reflected waves. As a result, noise caused by the reflected waves can be diffused around the electromagnetic wave shield 1.

[0039] 4 and 5 , the first cell 11 has a first line 30 connecting the first point 21 and the second point 22. The first line 30 intersects with the straight line VL connecting the first point 21 and the second point 22. The first line 30 is curved. As a result, when an electromagnetic wave (incident wave) incident on the electromagnetic wave shield 1 hits the first line 30, the reflected wave (see arrow Rw shown in FIG. 5 ) can be diffused in all directions.

[0040] The wavelength λ1 of the first line 30 (see FIG. 5 ) is the length between the first point 21 and the second point 22 divided by a natural number greater than or equal to 1. In this embodiment, the wavelength λ1 of the first line 30 is the length between the first point 21 and the second point 22 divided by 1. That is, the first line 30 has a number of wavelengths corresponding to the above natural numbers. Specifically, the wavelength λ1 of the first line 30 in this embodiment is equal to the length between the first point 21 and the second point 22. As a result, when an electromagnetic wave (incident wave) incident on the electromagnetic wave shield 1 hits the first line 30, the reflected wave is diffused in all directions, and the generation of polarized wave at the reflection destination is suppressed.

[0041] Furthermore, since the first cell 11 of this embodiment has a shape based on a regular hexagon, the wavelength λ1 of the first lines 30 located on each side of the first cell 11 is equal to the length between the first point 21 and the second point 22. In other words, the wavelengths λ1 of the first lines 30 located on each side of the first cell 11 do not have a phase difference from each other.

[0042] (First Semicircle and Second Semicircle) As shown in FIGS. 4 and 5, the first line 30 in this embodiment includes a first semicircle 31 and a second semicircle 32.

[0043] Preferably, the first semicircle 31 has a diameter d1 (see FIG. 4) that is equal to or smaller than half the length between the first point 21 and the second point 22. The second semicircle 32 also has a diameter d2 (see FIG. 4) that is equal to or smaller than half the length between the first point 21 and the second point 22.

[0044] In this embodiment, the diameter d1 of the first semicircle 31 is half the length between the first point 21 and the second point 22. The diameter d2 of the second semicircle 32 is half the length between the first point 21 and the second point 22. In other words, the diameter d1 of the first semicircle 31 is the same size as the diameter d2 of the second semicircle 32.

[0045] The second semicircle 32 is connected to the first semicircle 31. The connection point between the first semicircle 31 and the second semicircle 32 is located at the midpoint M of the straight line VL.

[0046] The first semicircle 31 and the second semicircle 32 are located on opposite sides of a straight line VL that connects the first point 21 and the second point 22. In this embodiment, the first semicircle 31 is located outside the first cell 11. The second semicircle 32 is located inside the first cell 11.

[0047] In this embodiment, electromagnetic waves (incident waves) incident on the electromagnetic wave shield 1 hit the first semicircle 31 and the second semicircle 32, thereby enabling the reflected waves to be diffused in all directions. Furthermore, the first semicircle 31 and the second semicircle 32 are located on opposite sides of the line VL connecting the first point 21 and the second point 22. Therefore, when the incident wave hits the first semicircle 31 and the second semicircle 32, the reflected wave when the incident wave hits the first semicircle 31 and the reflected wave when the incident wave hits the second semicircle 32 are diffused isotropically in all directions (see arrow Rw in FIG. 5 ). As a result, the reflected waves can be diffused isotropically in all directions by the first cell 11 as a whole.

[0048] (Pitch) The symbol P shown in FIG. 2 is the distance (pitch) between the center of gravity Cg1 of the first cell 11 and the center of gravity Cg2 of the second cell 12. Preferably, the pitch P is 25 μm or more and 100 μm or less. If the pitch P is 25 μm or more and 100 μm or less, the transparency of the electromagnetic wave shield 1 can be ensured while sufficient shielding performance, which is the main function of the electromagnetic wave shield 1, can be obtained. This point will be described in detail with reference to FIG. 6.

[0049] FIG. 6 is a graph showing the relationship between the frequency (unit: GHz) of the electromagnetic wave and the shielding performance (unit: dB) of each sample when a predetermined electromagnetic wave is incident on each of four samples (first to fourth samples S1 to S4) each having a different numerical value for the pitch P.

[0050] The horizontal axis of the graph shown in Fig. 6 represents the frequency (GHz) of the electromagnetic waves. The vertical axis of the graph shown in Fig. 6 represents the shielding performance (dB). In general, the value of shielding performance is a number that relatively expresses the degree to which the electromagnetic waves are attenuated, and is a logarithmic representation of the ratio (attenuation) of the electric field strength before and after shielding.

[0051] In the graph shown in FIG. 6, the pitch P in the first sample S1 is 25 μm. This "25 μm" is assumed to be equal to or less than 1 / 10 of the wavelength of the electromagnetic wave. The pitch P in the second sample S2 is 50 μm. This "50 μm" is assumed to be equal to or less than 1 / 5 of the wavelength of the electromagnetic wave. The pitch P in the third sample S3 is 100 μm. This "100 μm" is assumed to be equal to or less than 1 / 2 of the wavelength of the electromagnetic wave. The pitch P in the fourth sample S4 is 200 μm. In all four samples, the line width of the thin metal wires 13 is 2.4 μm.

[0052] Here, if the shielding performance (dB) is −40 dB or less, a transmission attenuation (shielding rate) of 99% or more can be obtained. Based on this premise, for the sake of convenience, the graph in Figure 6 shows, with a dashed line, the region X where a transmission attenuation of 99% or more can be obtained (the shielding rate when each sample shields electromagnetic waves incident on the sample).

[0053] All of samples S1 to S3 included a portion located within region X shown in Figure 6. Specifically, all of samples S1 to S3 were able to achieve a transmission attenuation of 99% or more in any frequency range from 0.01 GHz to 40 GHz on the horizontal axis of the graph in Figure 6. In other words, if the pitch P was 25 μm or more and 100 μm or less, a transmission attenuation of 99% or more was possible in any frequency range from 0.01 GHz to 40 GHz. Thus, if the pitch P was 25 μm or more and 100 μm or less, sufficient shielding performance could be obtained.

[0054] 6, when the pitch P is larger than that of sample S3, transmission attenuation of 99% or more cannot be obtained in the frequency range of 0.01 GHz to 40 GHz. In other words, when the pitch P exceeds 101 μm, sufficient shielding performance cannot be obtained.

[0055] In particular, for the fourth sample S4 (pitch P is 200 μm), the values ​​on the vertical axis in the graph of Fig. 6 are greater than -40 dB over the entire frequency range from 0.01 GHz to 40 GHz. Thus, the fourth sample S4 is located outside the region indicated by the dashed line in the graph of Fig. 6, and does not achieve a transmission reduction of 99% or more.

[0056] On the other hand, in view of the simulation results for samples S1 to S4 shown in the graph of Fig. 6, it is expected that a transmission attenuation of 99% or more can be obtained in the frequency range of 0.01 GHz to 40 GHz if the pitch P is less than 25 µm. In other words, even if the pitch P is less than 25 µm, the shielding performance is improved.

[0057] However, if the pitch P is less than 25 μm, the distance between the fine metal wires 13, 13 that make up the cells 10 (first cells 11) becomes narrow. As a result, when the electromagnetic wave shield 1 is viewed from the side where the first surface 3 is located, the fine metal wires 13 provided on the first surface 3 become noticeable. This impairs the transparency of the electromagnetic wave shield 1. Specifically, there is a risk that the total light transmittance of the electromagnetic wave shield 1 will fall below 70%. From this perspective, in order to maintain the total light transmittance at 70% or higher, it is necessary to set the pitch P to 25 μm or higher.

[0058] From the above, if the pitch P is 25 μm or more and 100 μm or less, it is possible to obtain sufficient shielding performance while ensuring the transparency of the electromagnetic wave shield 1.

[0059] [Considerations Regarding Reflected Waves] Next, with reference to FIGS. 7 to 9 , the state of the reflected wave Rw2 when an electromagnetic wave (incident wave Iw) incident on the electromagnetic wave shield 1 according to an embodiment of the present disclosure is reflected will be described in comparison with the state of the reflected wave Rw1 when an electromagnetic wave (incident wave Iw) incident on the electromagnetic wave shield 100 according to a configuration of the prior art (hereinafter referred to as the “conventional configuration”) is reflected.

[0060] An example of a configuration of the prior art is an electromagnetic wave shield 100 made up of lattice-shaped cells 101 shown in Fig. 7. In the conventional configuration, the thin metal wires 102 of the cells 101 are formed in a straight line. In other words, the electromagnetic wave shield 100 according to the conventional configuration has a different configuration from the electromagnetic wave shield 1 according to the embodiment of the present disclosure.

[0061] 8 is an image diagram that schematically shows the state of a reflected wave reflected from the upper surface of the electromagnetic wave shield 100 when a predetermined electromagnetic wave is irradiated onto the electromagnetic wave shield 100 using a simulation device (Ansys HFSS manufactured by Ansys). In FIG. 8, the state of the reflected wave is expressed by shades of black and white.

[0062] 9 is an image diagram that schematically shows the state of a wave reflected from the first surface 3 when a predetermined electromagnetic wave is irradiated onto the electromagnetic wave shield 1 according to an embodiment of the present disclosure using a simulation device (Ansys HFSS manufactured by Ansys). In Fig. 9 , as in Fig. 8 , the state of the reflected wave is expressed by shades of black and white.

[0063] 8, in the electromagnetic wave shield 100 according to the conventional configuration, an electromagnetic wave (incident wave Iw) incident on a straight thin metal wire 102 (the thin metal wire 102 is not shown in FIG. 8) is reflected in a certain direction. Specifically, the black and white shading shown in FIG. 8 is uniformly dark across the entire top surface of the electromagnetic wave shield 100. That is, the reflected wave Rw1 travels upward in the electromagnetic wave shield 100 shown in FIG. 8. As a result, the degree of diffusion of electromagnetic noise at the reflection destination is relatively low. This increases electromagnetic wave noise around the electromagnetic wave shield 100.

[0064] In contrast, referring to Fig. 9, in the electromagnetic wave shield 1 according to the embodiment of the present disclosure, the electromagnetic wave (incident wave Iw) that strikes the curved first line 30 (the first line 30 is not shown in Fig. 9) is reflected diffusely in all directions. Specifically, the black and white shading shown in Fig. 9 spreads radially upward from the first surface 3 of the electromagnetic wave shield 1. That is, the reflected wave Rw2 propagates radially upward from the first surface 3 of the electromagnetic wave shield 1 shown in Fig. 9. As a result, the degree of diffusion of the electromagnetic noise at the reflection destination is relatively high. This reduces the electromagnetic wave noise around the electromagnetic wave shield 1.

[0065] If the diffusion factor of the reflected wave in the electromagnetic wave shield 100 according to the conventional configuration is assumed to be "1.0," the diffusion factor of the reflected wave in the electromagnetic wave shield 1 according to the embodiment of the present disclosure is 1.5 or more and 3.0 or less.

[0066] 10 to 13, the state of the light beam when visible light passes through the electromagnetic wave shield 1 according to the embodiment of the present disclosure will be described in comparison with the state of the light beam in the electromagnetic wave shield 100 according to the conventional configuration (see FIG. 7). Note that FIGS. 11 and 13 show the results of an analysis of the state of the light beam (the light intensity of first-order diffracted light in the transmitted light projected onto a predetermined screen) using image analysis software "ImageJ 1.54g."

[0067] 10 toward the upper surface of the electromagnetic wave shield 100 according to the conventional configuration (incident light IL) is transmitted downward from the lower surface of the electromagnetic wave shield 100. The visible light transmitted downward from the lower surface of the electromagnetic wave shield 100 (transmitted light TL1) is dispersed in all directions downward from the lower surface of the electromagnetic wave shield 100 (toward the lower side of the paper in FIG. 8) (see first-order diffracted light hm1 shown in FIG. 10).

[0068] The main reason why the transmitted light TL1 shown in FIG. 10 is dispersed in all directions is that, in the electromagnetic wave shield 100 according to the conventional configuration, the cells 101 are formed in a lattice pattern. That is, in the lattice-patterned cells 101, the thin metal wires 102 that form the cells 101 are formed in straight lines. With this configuration, when the incident light IL passes near the thin metal wires 102 that are formed in straight lines, it is diffracted only in a direction perpendicular to the extension direction of the thin metal wires 102. As a result, the transmitted light TL1 is diffused only in all directions. In this way, in the electromagnetic wave shield 100 according to the conventional configuration, the incident light IL is not diffracted in all directions, and therefore the degree of dispersion of the transmitted light TL1 is relatively small.

[0069] In the electromagnetic wave shield 100 according to the conventional configuration, the first-order diffracted light hm1 (light having a frequency twice that of the fundamental wave in the transmitted light TL1) shown in FIG. 11 is concentrated in a cross shape on the screen. The first-order diffracted light hm1 concentrated in a cross shape has a relatively strong light intensity. In other words, the light intensity of the transmitted light TL1 is not reduced. Therefore, in the electromagnetic wave shield 100 according to the conventional configuration, a beam of light can be clearly seen.

[0070] 12 , in the electromagnetic wave shield 1 according to the embodiment of the present disclosure, visible light (incident light IL) incident toward the first surface 3 of the electromagnetic wave shield 1 is transmitted downward (toward the lower side of the paper in FIG. 10 ) from the lower surface of the electromagnetic wave shield 1. The visible light (transmitted light TL2) transmitted downward from the lower surface of the electromagnetic wave shield 1 is dispersed in all directions below the electromagnetic wave shield 1 (see first-order diffracted light hm2 shown in FIG. 12 ).

[0071] 12 is dispersed in all directions. This is mainly because, in the first cell 11 based on a regular hexagon, the first line 30 (thin metal wire 13) forming the first cell 11 intersects with the straight line VL connecting the first point 21 and the second point 22 and is formed in a curved shape. With this configuration, the incident light IL is diffracted in all directions when passing near the curved first line 30. This diffraction results in a relatively large degree of dispersion of the transmitted light TL2 that passes through the electromagnetic wave shield 1. As a result, the transmitted light TL2 is diffused in all directions.

[0072] In the electromagnetic wave shield 1 according to an embodiment of the present disclosure, the first-order diffracted light hm2 (light having a frequency twice that of the fundamental wave in the transmitted light TL2) shown in FIG. 13 is dispersed radially on the screen. In this dispersed state, the light intensity of the transmitted light TL2 projected onto the screen becomes relatively small. That is, the overall light intensity of the visible light (transmitted light TL2) that has passed through the electromagnetic wave shield 1 is reduced. As a result, the electromagnetic wave shield 1 according to an embodiment of the present disclosure can suppress the generation of light beams.

[0073] FIG. 14 is a graph showing the relationship between the light intensity (unit: a.u.) of the first harmonic and the width of the first-order diffracted light (horizontal axis / unit: a.u.) for transmitted light TL1 that has passed through an electromagnetic wave shield 100 according to a configuration of the prior art and transmitted light TL2 that has passed through an electromagnetic wave shield 1 according to an embodiment of the present disclosure.

[0074] 14, the intensity of first-order diffracted light hm1 in transmitted light TL1 through the electromagnetic wave shield 100 according to the configuration of the conventional technology is indicated by the symbol H1. Also, the intensity of first-order diffracted light hm2 in transmitted light TL2 through the electromagnetic wave shield 1 according to the embodiment of the present disclosure is indicated by the symbol H2.

[0075] As shown in Fig. 14 , even the electromagnetic wave shield 1 according to the embodiment of the present disclosure produces a fair amount of light beams. However, the light intensity of first-order diffracted light is significantly reduced in the electromagnetic wave shield 1 compared to the electromagnetic wave shield 100 according to the conventional configuration. Specifically, around "4" on the horizontal axis shown in Fig. 14 , the light intensity H1 of first-order diffracted light in the electromagnetic wave shield 100 according to the conventional configuration is "1 a.u.", while the light intensity H2 of the first-order harmonic in the electromagnetic wave shield 1 according to the embodiment of the present disclosure is below "0.4 a.u."

[0076] As described above, the electromagnetic wave shield 1 according to the embodiment of the present disclosure can suppress the generation of light beams more effectively than the electromagnetic wave shield 100 according to the conventional configuration.

[0077] [Regarding the relationship between the height of the metal thin wire and the diffraction of incident light] Next, assuming the cross-sectional configuration of the metal thin wire 13 in an embodiment of the present disclosure, we will explain the relationship between the height of the metal thin wire 13 and the diffraction of incident light IL passing between the metal thin wires 13 and the effect (suppression of light beams).

[0078] Before describing the configuration according to the embodiment of the present disclosure, the cross-sectional configuration of the electromagnetic wave shield 100 according to the conventional configuration will be described again with reference to Fig. 15. Fig. 15 is a schematic diagram in which incident light IL and transmitted light TL1 are superimposed on the cross-sectional view taken along line XV-XV in Fig. 7.

[0079] The electromagnetic wave shield 100 shown in Fig. 15 includes a substrate 103 made of a transparent resin material and a plurality of thin metal wires 102. The thin metal wires 102 are formed on the upper surface of the substrate 103 by etching. The thin metal wires 102 obtained by etching protrude upward from the upper surface of the substrate 103. The height of the thin metal wires 102 is limited to stabilize the shape of the thin metal wires 102 protruding upward from the upper surface of the substrate 103. The height of the thin metal wires 102 is the dimension LH1 shown in Fig. 15, which corresponds to the distance from the upper surface of the substrate 103 to the upper surfaces of the thin metal wires 102.

[0080] Fig. 16 is a schematic diagram of the electromagnetic wave shield 1 according to the embodiment of the present disclosure, in which incident light IL and transmitted light TL2 are superimposed on the cross-sectional view taken along line XVI-XVI in Fig. 4. The cross-sectional configuration of the thin metal wires 13 shown in Fig. 16 is the same as the cross-sectional configuration shown in Fig. 3. Note that the first layer 4 and second layer 5 shown in Fig. 3 are not shown in Fig. 16.

[0081] As shown in FIG. 16 , in the embodiment of the present disclosure, a groove 6 is provided on the first surface 3 of the insulator 2, and the thin metal wires 13 include a conductive metal embedded in the groove 6. In the thin metal wires 13, the shape of the conductive metal is stably maintained while embedded in the groove 6. Furthermore, the depth of the groove 6 (dimension Ld shown in FIG. 3 ) in the thickness direction of the insulator 2 (thickness direction of the second layer 5 shown in FIG. 3 ) can be set relatively large. As a result, in the embodiment of the present disclosure, the height of the thin metal wires 13 (dimension LH2 shown in FIG. 16 ) can be made relatively large. That is, in the embodiment of the present disclosure, the height of the thin metal wires 13 (dimension LH2) can be made larger than the height of the thin metal wires 102 of the conventional configuration (dimension LH1 shown in FIG. 15 ). Note that the height of the thin metal wires 13 (dimension LH2) corresponds to the distance from the bottom surface of the groove 6 to the top surface of the thin metal wires 13.

[0082] 15 , as described above, visible light (incident light IL) incident toward the upper surface of the electromagnetic shield 100 according to the conventional configuration is transmitted outward from the lower surface of the electromagnetic shield 100. Specifically, the incident light IL passes between the thin metal wires 102 (inside the cells 101 shown in FIG. 7 ). The incident light IL then transmits outward from the electromagnetic shield 100 (toward the bottom of the paper in FIG. 15 ) from the upper surface of the substrate 103 toward the lower surface of the substrate 103.

[0083] 15, for convenience of explanation, the plane waves Wp (waves with parallel wavefronts made up of a series of in-phase dots) and the circular waves Wc (waves with concentric wavefronts) of the incident light IL and the transmitted light TL1 are schematically shown using solid lines. Also, for convenience of explanation, it is assumed that the distance between the fine metal wires 102 shown in FIG. 15 (dimension SD0 shown in FIG. 15) is the same as the distance between the fine metal wires 13 shown in FIG. 16.

[0084] As shown in FIG. 15 , a plane wave Wp of visible light (incident light IL) incident toward the top surface of the electromagnetic wave shield 100 passes between the thin metal wires 102. At this time, near the side walls of the thin metal wires, some elementary waves (not shown) of the incident light IL are reflected by the side walls of the thin metal wires 102, and the reflected waves (not shown, hereinafter referred to as "wall-reflected waves") interfere with the plane wave Wp of the incident light IL. Due to this interference, some of the plane wave Wp of the incident light IL is weakened near the side walls of the thin metal wires 102 (region E1 shown in FIG. 15 ). As a result, it is estimated that the opening width (dimension SD1) of the plane wave Wp of the incident light IL in the left-right direction immediately after passing through the thin metal wires 102 is substantially smaller than the distance between the thin metal wires 102. Based on this assumption, and based on the so-called Huygens principle, a portion of the incident light IL that passes between the metal thin wires 102 (dimension SD1) becomes a circular wave Wc and is diffracted toward the underside of the metal thin wire 102.

[0085] 16 according to the embodiment of the present disclosure, visible light (incident light IL) incident toward the first surface 3 of the electromagnetic shield 1 also transmits outward from the lower surface of the electromagnetic shield 1. Specifically, the incident light IL passes between the thin metal wires 13 (openings corresponding to the cells 10 shown in FIG. 4 ). The incident light IL then transmits outward from the electromagnetic shield 1 (toward the bottom of the paper in FIG. 16 ) from the first surface 3 of the insulator 2 toward the lower surface of the insulator 2.

[0086] 16, similarly to FIG. 15, the plane wave Wp and circular wave Wc of the incident light IL and the transmitted light TL2 are schematically shown using solid lines.

[0087] As shown in Fig. 16 , a plane wave Wp of visible light (incident light IL) incident toward the first surface 3 of the electromagnetic wave shield 1 passes between the thin metal wires 13. At this time, similar to the cross-sectional configuration of Fig. 15 , near the side walls of the thin metal wires 13, some elementary waves (not shown) of the incident light IL are reflected by the side walls of the thin metal wires 13, and the wall-reflected waves (not shown) interfere with the plane wave Wp of the incident light IL. This interference weakens some of the plane wave Wp of the incident light IL near the side walls of the thin metal wires 13 (part E2 shown in Fig. 16 ). As a result, it is presumed that the opening width (dimension SD2) in the left-right direction of the plane wave Wp of the incident light IL immediately after passing through the thin metal wires 13, 13, is substantially smaller than the distance (dimension SD0) between the thin metal wires 13. Based on this assumption and on Huygens' principle, part of the incident light IL that passes between the thin metal wires 13 becomes a circular wave Wc and is diffracted toward the lower surface side of the thin metal wire 13.

[0088] As described above, in the embodiment of the present disclosure, the thin metal wires 13 include a conductive metal embedded in the grooves 6, and therefore the height (dimension LH2) of the thin metal wires 13 can be made greater than the height (dimension LH1 shown in FIG. 15 ) of the thin metal wires 102 in the conventional configuration. That is, in the embodiment of the present disclosure, the distance over which the incident light IL travels between the thin metal wires 13 (corresponding to the dimension LH2, which is the height of the thin metal wires 13) is greater than the distance over which the incident light IL travels between the thin metal wires 102 in the conventional configuration (dimension LH1). Therefore, near the side walls of the thin metal wires 13, the degree of interference between the wall-reflected wave and the plane wave Wp of the incident light IL increases as the incident light IL passes between the thin metal wires 13. As a result, the region E2 shown in FIG. 16 is greater than the region E1 shown in FIG. 15 . Specifically, in the embodiment of the present disclosure, the opening width (dimension SD2) in the left-right direction of the plane wave Wp of the incident light IL immediately after passing through the thin metal wires 13, 13 is smaller than the dimension SD1 shown in FIG.

[0089] According to Huygens' principle, it is generally known that the degree of diffraction (i.e., the spread of light) increases as the width of the opening through which the light passes becomes smaller.

[0090] Based on Huygens' principle, considering that the dimension SD2 shown in FIG. 16 is smaller than the dimension SD1 shown in FIG. 15 , the electromagnetic shield 1 according to the embodiment of the present disclosure exhibits a greater degree of diffraction of the incident light IL than the conventional configuration. Specifically, in the electromagnetic shield 1 according to the embodiment of the present disclosure, compared to the conventional configuration, visible light (incident light IL) incident toward the first surface 3 of the electromagnetic shield 1 passes between adjacent thin metal wires 13 and then undergoes multiple diffraction toward the underside of each thin metal wire 13, resulting in significant diffraction (see FIG. 16 ). Thus, in the embodiment of the present disclosure, the diffraction of the incident light IL results in a relatively large degree of dispersion of the transmitted light TL2 that passes through the electromagnetic shield 1, causing the transmitted light TL2 to diffuse in all directions. As a result, the electromagnetic shield 1 according to the embodiment of the present disclosure is able to suppress the generation of light beams compared to the conventional configuration.

[0091] [Modifications of the embodiment] In the above embodiment, the first line 30 includes the first semicircle 31 and the second semicircle 32, but is not limited to this. For example, as in the modifications shown in Figures 17 to 19, the first line 30 does not have to include the first semicircle 31 and the second semicircle 32.

[0092] 17 , an electromagnetic wave shield 40 according to this modification includes an insulator 41. Although not shown, the insulator 41 has the same configuration (first surface 3, first layer 4, second layer 5, and groove 6) as the insulator 2 of the above embodiment.

[0093] The electromagnetic wave shield 40 includes a plurality of cells 50. Each cell 50 is formed of thin metal wires 42. Each cell 50 is formed in a closed shape by the thin metal wires 42. The line width of the thin metal wires 42 is 1.0 μm or more and 3.0 μm or less, similar to the above embodiment.

[0094] In this modification, any one of the multiple cells 50 is referred to as a "first cell 51." Also, the cell 50 adjacent to the first cell 51 (the cell 50 located at the upper right of the first cell 51 in FIG. 17 ) is referred to as a "second cell 52."

[0095] The first cells 51 and the second cells 52 each have a regular hexagonal base, and the pitch P is 25 μm or more and 100 μm or less, similar to the above embodiment.

[0096] 18 , the first cell 51 has a first line 54 that connects a first point 61 and a second point 62. The first line 54 intersects with a straight line VL that connects the first point 61 and the second point 62.

[0097] 19 , the first line 54 is a sine curve. The first line 54 includes one or more wavelengths λ2 on a straight line VL connecting the first point 61 and the second point 62. In this modification, the first line 30 is made up of three wavelengths λ2. That is, in this modification, each wavelength λ2 on the first line 54 is the length between the first point 61 and the second point 62 divided by three.

[0098] The wavelength λ2 of each of the first lines 54 is 1 / (4√3) or more and 1 / √3 or less times the pitch P, which is the distance between the center of gravity Cg1 of the first cell 51 and the center of gravity Cg2 of the second cell 52. Furthermore, the amplitude A of the first lines 54 is 1 / 20 or more and 1 / 3 or less times the wavelength λ2. This makes it possible to appropriately form the first lines 54 as sine curves in the first cells 51 based on a regular hexagon. As a result, when electromagnetic waves incident on the electromagnetic wave shield 40 hit the first lines 54, the reflected waves can be diffused in all directions.

[0099] The above-mentioned "amplitude" corresponds to the distance from the straight line VL connecting the first point 61 and the second point 62 to the highest peak or deepest valley contained in one wavelength λ2 in a direction perpendicular to the straight line VL (dimension A shown in Figure 19).

[0100] [Other Embodiments] In the above embodiment, the electromagnetic wave shield 1 is provided on a windowpane of a building (see FIG. 1 ), but the present invention is not limited to this. That is, the electromagnetic wave shield 1 may be provided on a windowpane in a room installed inside a building. Even in such a case, the above-described effects of the electromagnetic wave shield 1 (diffusion of noise due to reflected waves and suppression of light beams) can be obtained. The same applies to the electromagnetic wave shield 40 according to the above-described modified example. Note that if the electromagnetic wave shield 1 or the electromagnetic wave shield 40 is installed in a darkroom (a room where visible light does not enter) installed inside a building, the above-described effects of suppressing the generation of light beams will be irrelevant.

[0101] In the above embodiment, the first line 30 does not have to be formed as a perfect curve due to reasons such as precision due to design or manufacturing. In other words, the first line 30 does not need to be formed as a highly precise curve in design or manufacturing, as long as it is formed as a curve that can diffuse reflected waves isotropically in all directions. The same applies to the first line 54 shown in the above modified example.

[0102] In the above embodiment, a "regular hexagon" is shown as an example of a regular polygon that serves as the base of the cell 20, but this shape is not limited to this. In other words, regular polygons include an equilateral triangle, a square, and a regular pentagon. However, in order to obtain the effects of the electromagnetic wave shield 1 (diffusion of noise due to reflected waves and suppression of light beams), it is preferable that the regular polygon that serves as the base of the cell 20 be a "regular hexagon," as shown in the above embodiment. The same applies to the electromagnetic wave shield 40 according to the above modified example.

[0103] [Summary] As a first disclosure, an electromagnetic wave shield 1 includes a sheet-like insulator 2 having a first surface 3, and first cells 11 provided on the first surface 3 of the insulator 2 and formed of thin metal wires 13. The first cells 11 are provided at positions that form a regular polygon when connected to each other by straight lines, and have a plurality of vertices 20 including a first point 21 and a second point 22, and a first line 30 that connects the first point 21 and the second point 22 and intersects with a straight line VL that connects the first point 21 and the second point 22. The first line 30 is a curve.

[0104] In the first disclosure, the first line 30 (thin metal wire 13) forming the first cell 11 intersects with the straight line VL connecting the first point 21 and the second point 22 and is formed in a curved shape, so that when electromagnetic waves incident on the electromagnetic wave shield 1 hit the first line 30, the reflected waves are diffused in all directions.

[0105] The first cells 11 are arranged at positions that form a regular polygon when connected to each other by straight lines. That is, the first cells 11, which are based on a regular polygon, are isotropic. As a result, in the electromagnetic wave shield 1, the curved first wires 30 (thin metal wires 13) are isotropically arranged in the first cells 11. As a result, when electromagnetic waves incident on the electromagnetic wave shield 1 hit the first wires 30, the reflected waves are diffused isotropically in all directions.

[0106] Therefore, in the electromagnetic wave shield 1, the degree of diffusion of noise caused by electromagnetic waves is relatively high in the destination of the reflected waves. As a result, noise caused by reflected waves can be diffused around the electromagnetic wave shield 1. Furthermore, the electromagnetic wave shield 1 according to the first disclosure can also suppress the generation of light beams, as described with reference to FIGS. 11 to 13 . The electromagnetic wave shield 40 according to the above-described modification can also achieve the same effects as those of the first disclosure (diffusion of noise caused by reflected waves and suppression of light beams).

[0107] As a second disclosure, the plurality of vertices 20 further includes a third point 23 provided at a position obtained by rotating the second point 22 by 120 degrees around the first point 21 .

[0108] In this second disclosure, the multiple vertices 20 further include a third point 23 located at a position obtained by rotating the second point 22 by 120 degrees around the first point 21. This allows the base shape of the first cell 11 to be a "regular hexagon." The first cell 11 based on a regular hexagon has isotropy. That is, the curved first wires 30 (thin metal wires 13) can be isotropically arranged on each side of the first cell 11 based on a regular hexagon. As a result, when electromagnetic waves incident on the electromagnetic shield 1 hit the first wires 30, the reflected waves are isotropically diffused in all directions. Therefore, in the second disclosure, it is possible to further increase the degree of diffusion of noise caused by electromagnetic waves at the destination of the reflected waves. As a result, noise caused by reflected waves can be diffused around the electromagnetic shield 1. Furthermore, the electromagnetic shield 40 according to the above-described modified example can also achieve the same effects as those of the second disclosure.

[0109] As a third disclosure, the first line 30 includes a first semicircle 31 having a diameter d1 equal to or less than half the length between the first point 21 and the second point 22, and a second semicircle 32 having a diameter d2 equal to or less than half the length between the first point 21 and the second point 22 and connected to the first semicircle 31. The first semicircle 31 and the second semicircle 32 are located on opposite sides of a straight line VL connecting the first point 21 and the second point 22.

[0110] In the third disclosure, electromagnetic waves (incident waves) incident on the electromagnetic wave shield 1 strike the first semicircle 31 and the second semicircle 32, thereby enabling the reflected waves to be diffused in all directions. Furthermore, because the first semicircle 31 and the second semicircle 32 are located on opposite sides of the line VL connecting the first point 21 and the second point 22, when the incident waves strike the first semicircle 31 and the second semicircle 32, the reflected waves resulting from the incident waves striking the first semicircle 31 and the second semicircle 32 are diffused isotropically in all directions (see arrow Rw in FIG. 5 ). As a result, the reflected waves can be diffused isotropically in all directions across the entire first cell 11. Furthermore, the electromagnetic wave shield 40 according to the above-described modification can also achieve the same effects as those of the third disclosure.

[0111] As a fourth disclosure, the electromagnetic wave shield 40 according to the above modification further includes a second cell 52 that is provided on a first surface of the insulator 41 and is formed of thin metal wires 42, and that is adjacent to the first cell 51. The first line 54 is a sinusoidal curve. The wavelength λ2 of the first line 54 is not less than 1 / (4√3) times and not more than 1 / √3 times the pitch P, which is the distance between the center of gravity Cg1 of the first cell 51 and the center of gravity Cg2 of the second cell 52. The amplitude of the first line 54 is not less than 1 / 20 times and not more than 1 / 3 times the wavelength.

[0112] In the fourth disclosure, the first lines 54 can be appropriately formed as sine curves in the first cells 51 based on a regular hexagon. As a result, when electromagnetic waves incident on the electromagnetic wave shield 40 hit the first lines 54, the reflected waves can be diffused in all directions.

[0113] As a fifth disclosure, the wavelength λ1 (see FIG. 5) of the first line 30 is the length between the first point 21 and the second point 22 divided by a natural number greater than or equal to 1. Similarly, the wavelength λ2 (see FIG. 17) of the first line 54 in the above modification is the length between the first point 51 and the second point 52 divided by a natural number greater than or equal to 1.

[0114] In the fifth disclosure, the first line 30 forms wavelengths whose number corresponds to the natural number. As a result, when electromagnetic waves incident on the electromagnetic wave shield 1 hit the first line 30, the reflected waves can be diffused in all directions and the generation of polarized waves at the reflection destination can be suppressed. Furthermore, the electromagnetic wave shield 40 according to the above-described modified example can also achieve the same effects as those of the fifth disclosure.

[0115] As a sixth disclosure, the electromagnetic wave shield 1 further includes a second cell 12 that is provided on the first surface 3 of the insulator 2, is formed of thin metal wires 13, and is adjacent to the first cell 11. A pitch P, which is the distance between the center of gravity Cg1 of the first cell 11 and the center of gravity Cg2 of the second cell 12, is 25 μm or more and 100 μm or less.

[0116] In the sixth disclosure, by setting the pitch P to be 25 μm or more and 100 μm or less, it is possible to obtain sufficient shielding performance while ensuring the transparency of the electromagnetic wave shield 1. Furthermore, the electromagnetic wave shield 40 according to the above-described modified example can also achieve the same effects as those of the sixth disclosure.

[0117] As a seventh disclosure, the line width of the thin metal wires 13 forming the first cells 11 is 1.0 μm or more and 3.0 μm or less.

[0118] In the seventh disclosure, by setting the line width of the thin metal wires 13 to be 1.0 μm or more and 3.0 μm or less, it becomes possible to appropriately reflect electromagnetic waves incident on the electromagnetic wave shield 1. As a result, it is possible to ensure shielding performance. Furthermore, the electromagnetic wave shield 40 according to the above-described modified example can also achieve the same effects as those of the seventh disclosure.

[0119] As an eighth disclosure, a groove 6 is provided on the first surface 3 of the insulator 2, and the thin metal wire 13 is embedded in the groove 6 and contains a conductive metal.

[0120] In the eighth disclosure, as described above, the shape of the conductive metal in the thin metal wires 13 is stably maintained while embedded in the grooves 6. Furthermore, the depth of the grooves 6 in the thickness direction of the insulator 2 (thickness direction of the second layer 5) can be set relatively large. That is, the height of the thin metal wires 13 (corresponding to the dimension LH2 shown in FIG. 16 ) can be formed relatively large. As a result, in the electromagnetic wave shield 1 according to the embodiment of the present disclosure, compared to the conventional configuration described above, visible light (incident light IL) incident toward the first surface 3 of the electromagnetic wave shield 1 passes between adjacent thin metal wires 13 and then undergoes multiple diffraction toward the underside of each thin metal wire 13, resulting in significant diffraction. This diffraction of the incident light IL results in a relatively large degree of dispersion of the transmitted light TL2 passing through the electromagnetic wave shield 1, causing the transmitted light TL2 to diffuse in all directions. As a result, the electromagnetic wave shield 1 according to the embodiment of the present disclosure can suppress the generation of light beams.

[0121] The present disclosure is industrially applicable as an electromagnetic wave shield.

[0122] 1, 40: Electromagnetic wave shield 2, 41: Insulator 3: First surface 4: First layer 5: Second layer 6: Groove 10, 50: Cell 11, 51: First cell 12, 52: Second cell 13, 42: Thin metal wire 20: Vertex 21, 61: First point 22, 62: Second point 23, 63: Third point 30, 54: First line 31: First semicircle 32: Second semicircle d1: Diameter of first semicircle d2: Diameter of second semicircle VL: Straight line P: Pitch Cg1: Center of gravity of first cell Cg2: Center of gravity of second cell

Claims

1. An electromagnetic wave shield comprising: a sheet-like insulator having a first surface; and first cells provided on the first surface of the insulator and formed of thin metal wires, wherein the first cells have a plurality of vertices arranged at positions that form a regular polygon when connected to each other by straight lines, the vertices including a first point and a second point; and a first line that connects the first point and the second point and intersects with the straight line connecting the first point and the second point, wherein the first line is a curve.

2. The electromagnetic wave shield according to claim 1, wherein the plurality of vertices further include a third point located at a position obtained by rotating the second point by 120 degrees around the first point.

3. The electromagnetic wave shield according to claim 1, wherein the first line includes: a first semicircle whose diameter is equal to or less than half the length between the first point and the second point; and a second semicircle whose diameter is equal to or less than half the length between the first point and the second point and is connected to the first semicircle; and the first semicircle and the second semicircle are located on opposite sides of a straight line connecting the first point and the second point.

4. The electromagnetic wave shield according to claim 2, further comprising a second cell adjacent to the first cell, the second cell being formed of a thin metal wire and provided on the first surface of the insulator, the first wire being a sine curve, the wavelength of the first wire being between 1 / (4√3) and 1 / √3 times the pitch, which is the distance between the center of gravity of the first cell and the center of gravity of the second cell, and the amplitude of the first wire being between 1 / 20 and 1 / 3 times the wavelength.

5. The electromagnetic wave shield according to claim 4, wherein the wavelength of the first line is the length between the first point and the second point divided by a natural number greater than or equal to 1.

6. The electromagnetic wave shield according to claim 1, further comprising a second cell adjacent to the first cell, the second cell being formed of thin metal wires and provided on the first surface of the insulator, wherein the pitch, which is the distance between the center of gravity of the first cell and the center of gravity of the second cell, is 25 μm or more and 100 μm or less.

7. The electromagnetic wave shield according to claim 1, wherein the line width of the thin metal wires forming the first cell is 1.0 μm or more and 3.0 μm or less.

8. The electromagnetic wave shield according to claim 1, wherein a groove is provided on the first surface of the insulator, and the thin metal wire includes a conductive metal embedded in the groove.

Images