Window structure and sheet

Abstract

A window structure according to one embodiment comprises: a window having a first surface and a second surface opposite to the first surface; and a sheet affixed to at least one of the first surface and the second surface of the window and including a matrix resin and an inorganic filler. At least one of the reflection intensity of radio waves in a predetermined band passing through the window and reaching the sheet and the reflection intensity of the radio waves in the predetermined band passing through the sheet and reaching the window is lower than the reflection intensity of the radio waves in the predetermined band passing through the window when either one of the first surface and the second surface, or both the first surface and the second surface, are in contact with air. The matrix resin is a thermoplastic resin or a thermosetting resin.

Description

Window structures and sheets

[0001] The present disclosure relates to window structures and sheets.

[0002] Patent Document 1 describes a window structure. The window of this window structure is composed of a support frame fixed to a wall and glass surrounded by a window frame. A portion of the surface of the glass is covered with a film that blocks radio waves. A portion of the glass surface where the film that blocks radio waves has been removed is formed as a window portion. The window portion allows specific radio waves to pass through and blocks radio waves other than the specific radio waves.

[0003] Non-Patent Document 1 describes a transmissive metasurface. The transmissive metasurface is in the form of a film. When attached to a window from the indoor side of a building, the transmissive metasurface bends millimeter-wave radio waves indoors to create an area around the foot of the building.

[0004] Japanese Patent Application Laid-Open No. 2006-87055

[0005] NTT Docomo, Inc. "World's first successful demonstration of transmitting indoor radio waves to the floor of an outdoor building using a transparent metasurface." Internet: <https: / / www.docomo.ne.jp / binary / pdf / info / news_release / topics_230130_04.pdf>

[0006] However, there are cases where it is required to make radio waves less likely to be blocked in buildings with window structures. For example, radio waves for 5G and 6G have the characteristic that they are more likely to be blocked by buildings and to attenuate depending on the building or distance than radio waves for 4G. Therefore, the communication environment inside the building may become unstable, making it impossible to receive radio waves.

[0007] One object of the present disclosure is to provide a window structure and sheet that can suppress the blocking and attenuation of radio waves by a building.

[0008] (1) A window structure according to the present disclosure includes a window having a first surface and a second surface opposite the first surface, and a sheet containing a matrix resin and an inorganic filler attached to at least one of the first and second surfaces of the window. At least one of the reflection intensity of radio waves in a predetermined band that pass through the window and reach the sheet and the reflection intensity of radio waves in a predetermined band that pass through the sheet and reach the window is lower than the reflection intensity of radio waves in the predetermined band that pass through a window when either the first surface or the second surface, or both the first and second surfaces, are in contact with air. The matrix resin is a thermoplastic resin or a thermosetting resin.

[0009] In this window structure, at least one of the reflection intensity of radio waves in a predetermined band that pass through the window and reach the sheet and the reflection intensity of radio waves in a predetermined band that pass through the sheet and reach the window is lower than the reflection intensity of radio waves in a predetermined band that pass through a window when the first surface, the second surface, or both of the surfaces of the window are in contact with air. In this way, the low reflection intensity of radio waves in the predetermined band increases the intensity of the radio waves that pass through the window and the sheet, based on the law of conservation of energy regarding the reflection and transmission of radio waves. By suppressing radio wave blocking and attenuation and increasing the transmission intensity of radio waves, the communication environment inside the building can be stabilized.

[0010] (2) In the above (1), the matrix resin may contain at least one of polystyrene and polyethylene.

[0011] (3) In the above (1) or (2), the sheet may contain 1 to 90% by volume of an inorganic filler.

[0012] (4) In any of the above (1) to (3), the inorganic filler may be at least one selected from the group consisting of barium titanate, calcium titanate, strontium titanate, and titanium-strontium-zirconia.

[0013] (5) In any of the above (1) to (4), the particle size of the inorganic filler may be 0.001 to 100 μm.

[0014] (6) In any of (1) to (5) above, the window structure may comprise a double-glazed window having two windows and a sheet attached to at least one of the first and second surfaces of the two windows.

[0015] (7) In the above (6), the double-glazed window may include a laminated glass interlayer.

[0016] (8) In the above (6), the double-glazed window may be provided with a heat-shielding layer.

[0017] (9) In any of the above (1) to (8), the periphery of the sheet may be fixed to the window with tape, or the sheet may be in close contact with the window.

[0018] (10) In any of the above (1) to (9), the sheet may include at least one of a pressure-sensitive adhesive layer and an adhesive layer.

[0019] (11) In any of the above (1) to (10), the sheet may be embossed.

[0020] (12) The sheet according to the present disclosure is a sheet that is attached to at least one of the first and second surfaces of a window having a first surface and a second surface opposite the first surface. The sheet includes a matrix resin and an inorganic filler. At least one of the reflection intensity of radio waves in a predetermined band that pass through the window and reach the sheet and the reflection intensity of radio waves in a predetermined band that pass through the sheet and reach the window is lower than the reflection intensity of radio waves in a predetermined band that pass through a window when either the first surface or the second surface, or both the first surface and the second surface, are in contact with air. This sheet provides the same effects as the window structure described above.

[0021] According to the present disclosure, it is possible to suppress the blocking and attenuation of radio waves caused by buildings.

[0022] FIG. 1 is a diagram schematically illustrating a window structure according to an embodiment. FIG. 2 is a cross-sectional view schematically illustrating a window structure according to an embodiment. FIG. 3 is a cross-sectional view illustrating a window and a sheet of the window structure according to an embodiment. FIG. 4 is a diagram for explaining reflection and transmission of radio waves with respect to the window of FIG. 3. FIG. 5 is a diagram for explaining reflection and transmission of radio waves with respect to the window and the sheet of FIG. 3. FIG. 6(a) is a cross-sectional view illustrating a window structure according to a first modified example. FIG. 6(b) is a cross-sectional view illustrating a window structure according to a second modified example. FIG. 7(a) is a cross-sectional view illustrating a window structure according to a third modified example. FIG. 7(b) is a cross-sectional view illustrating a window structure according to a fourth modified example. FIG. 8(a) is a cross-sectional view illustrating a window structure according to a fifth modified example. FIG. 8(b) is a cross-sectional view illustrating a window structure according to a sixth modified example. FIG. 9 is a diagram for explaining a radio wave intensity measurement test. FIG. 10 is a graph showing the results of the radio wave intensity measurement test.

[0023] Hereinafter, embodiments of the window structure and sheet according to the present disclosure will be described with reference to the drawings. In the description of the drawings, the same or corresponding elements are designated by the same reference numerals, and duplicate explanations will be omitted as appropriate. The drawings may be partially simplified or exaggerated to facilitate understanding, and the dimensional ratios and the like are not limited to those shown in the drawings.

[0024] FIG. 1 is a diagram schematically illustrating a window structure 1 according to an embodiment. The window structure 1 is provided in a building S. As an example, the window structure 1 includes a frame 2 fixed to the building S, a sash 3 located inside the frame 2, and a window 10 located inside the sash 3. The window 10 is made of, for example, glass. However, the material of the window 10 is not particularly limited.

[0025] Figure 2 is a cross-sectional view of the window structure 1 when cut along a plane extending in the extension direction of the window 10 and in the thickness direction of the window 10. As shown in Figure 2, the window 10 has a first surface 11 facing the exterior side of the building S and a second surface 12 facing the interior side of the building S. The window structure 1 has a sheet 20 attached to at least one of the first surface 11 and the second surface 12.

[0026] For example, the sheet 20 is attached to a portion of at least one of the first surface 11 and the second surface 12. In this case, the area of ​​the attached sheet 20 is smaller than the area of ​​the window 10. Note that the sheet 20 may be attached to the entirety of at least one of the first surface 11 and the second surface 12. In this case, the area of ​​the attached sheet 20 is approximately the same as the area of ​​the window 10.

[0027] 2 shows an example in which the sheet 20 is attached to the second surface 12. For example, the sheet 20 is in close contact with the window 10. For example, the window structure 1 has tape 30 for attaching the sheet 20 to the window 10. The tape 30 secures the periphery of the sheet 20 to the window 10. The sheet 20 has, for example, a first sheet surface 21 that is in close contact with the second surface 12 of the window 10, and a second sheet surface 22 that is opposite the first sheet surface 21. In this embodiment, the first sheet surface 21 is the surface that faces the exterior of the building S, and the second sheet surface 22 is the surface that faces the interior of the building S.

[0028] For example, the first sheet surface 21 and the second sheet surface 22 are flat surfaces. However, at least one of the first sheet surface 21 and the second sheet surface 22 may have an uneven surface. For example, the sheet 20 may be embossed.

[0029] The sheet 20 includes a matrix resin and an inorganic filler. The matrix resin is, for example, a thermoplastic resin or a thermosetting resin. The thermoplastic resin included in the sheet 20 may be, for example, polystyrene, polyethylene, polypropylene, acrylonitrile butadiene styrene (ABS), acrylic, polyamide, or the like. The thermoplastic resin included in the sheet 20 may be at least one selected from the group consisting of polystyrene and polyethylene. The thermosetting resin included in the sheet 20 may be, for example, a silicone resin, an epoxy resin, a phenolic resin, a melamine resin, a polyurethane resin, or the like. The thermosetting resin included in the sheet 20 may be, for example, a silicone resin.

[0030] For example, the inorganic filler contained in the sheet 20 is a high dielectric filler. The relative dielectric constant of the high dielectric filler may be, for example, 10 or more, 100 or more, 1000 or more, or 5000 or more. When the relative dielectric constant is high, it is easy to adjust the relative dielectric constant of the sheet 20 with a small filling amount. The relative dielectric constant of the high dielectric filler may be 10 or less, or may be 5 or less.

[0031] Examples of the inorganic filler include titanium-based fillers, zirconium-based fillers, and aluminum-based fillers. Examples of the titanium-based filler include barium titanate, calcium titanate, strontium titanate, zirconium oxide, and aluminum oxide. The inorganic filler may be at least one selected from the group consisting of barium titanate, calcium titanate, strontium titanate, and titanium-strontium-zirconia.

[0032] For example, the particle size of the inorganic filler contained in the sheet 20 is 0.001 to 100 μm. The particle size of the inorganic filler may be 0.01 μm or more, 0.05 μm or more, 0.1 μm or more, 0.5 μm or more, 1 μm or more, or 5 μm or more. The particle size of the inorganic filler may be 50 μm or less, 20 μm or less, or 10 μm or less.

[0033] For example, the sheet 20 contains 1 to 90 volume % of inorganic filler. The sheet 20 may contain 10 volume % or more, 20 volume % or more, 30 volume % or more, or 40 volume % or more of inorganic filler. The sheet 20 may contain 80 volume % or less, 70 volume % or less, 60 volume % or less, or 50 volume % or less of inorganic filler. The relative dielectric constant of the sheet 20 can be adjusted by the content of the inorganic filler. The content of the inorganic filler may be adjusted appropriately depending on the relative dielectric constant required for the sheet 20.

[0034] The sheet 20 may contain an epoxy resin and a barium titanate filler, or may contain a polystyrene resin and a barium titanate filler.

[0035] For example, the thickness of the sheet 20 (the distance from the first sheet surface 21 to the second sheet surface 22) is 100 to 200 μm. The relative dielectric constant of the sheet 20 can be adjusted by adjusting the thickness of the sheet 20. The thickness of the sheet 20 may be adjusted appropriately depending on the relative dielectric constant required for the sheet 20. As an example, the dielectric constant of the sheet 20 is 29 to 34.

[0036] FIG. 3 is a cross-sectional view schematically illustrating a window 10, a sheet 20, and radio waves W transmitted through or reflected by the window 10 and the sheet 20. The radio waves W are, for example, radio waves for 5G communication or radio waves for 6G communication. Radio waves for 5G communication and radio waves for 6G communication have the characteristic of being more easily blocked or attenuated in buildings than radio waves for 4G communication. In FIG. 3, the incident wave W and transmitted waves W4 and W7 are indicated by solid lines, the reflected waves W1, W5, and W6 are indicated by dashed lines, and the reflected waves W2 and W3 whose phases have been adjusted by the sheet 20 are indicated by thick dashed lines. The reflected waves W2 and W3 are reflected waves whose phases can be adjusted by the sheet 20.

[0037] The sheet 20 according to this embodiment has a function of controlling radio waves W. The sheet 20 is attached to the window 10 to increase the transmittance of radio waves W passing through the window 10. Radio waves W reaching a window 10 to which the sheet 20 is not attached are separated into a reflected wave W5 reflected at the first surface 11, a reflected wave W6 transmitted through the first surface 11 and reflected at the second surface 12, and a transmitted wave W7 transmitted through the second surface 12. Radio waves W reaching a window 10 to which the sheet 20 is attached are separated into a reflected wave W1 reflected at the first surface 11, a reflected wave W2 transmitted through the first surface 11 and reflected at the sheet first surface 21, a reflected wave W3 transmitted through the sheet first surface 21 and reflected at the sheet second surface 22, and a transmitted wave W4 transmitted through the sheet second surface 22. The intensity of the transmitted wave W4 is greater than the intensity of the transmitted wave W7. The window 10 to which the sheet 20 is attached has a higher transmittance of radio waves W than the window 10 to which the sheet 20 is not attached. For example, when the sheet 20 is attached to the second surface 12 of the window 10, the transmittance of radio waves W into the interior of the room is increased.

[0038] Fig. 4 is a diagram schematically showing the reflected waves and transmitted waves of radio waves W with respect to the window 10. Fig. 5 is a diagram schematically showing the reflected waves and transmitted waves of radio waves W with respect to the window 10 and the sheet 20. The reflection coefficient of radio waves W incident on the first surface 11 of the window 10 to which the sheet 20 is not attached is negative, and the reflection coefficient of radio waves W incident on the second surface 12 is positive. Because the thickness of the window 10 cannot be adjusted, it is not possible to cancel out the reflected waves W5 and W6 and strengthen the transmitted wave W7.

[0039] The reflection coefficient of radio waves W incident on the window 10 to which the sheet 20 is attached is negative at the first surface 11, negative at the second surface 12 (first sheet surface 21), and positive at the second sheet surface 22. Although the thickness of the window 10 cannot be adjusted, by adjusting the dielectric constant and thickness of the sheet 20, it is possible to adjust the intensity and phase of the reflected waves W2 and W3, thereby suppressing the reflected waves W2 and W3 and strengthening the transmitted wave W4.

[0040] The relative permittivity of the dielectric is ε ｒ , the wavelength in vacuum is λ ０ , the wavelength λ of the radio wave in the dielectric can be calculated by the following formula (1): As shown in formula (1), the larger the relative dielectric constant of the dielectric, the smaller the wavelength λ of the radio wave in the dielectric.

[0041] The dielectric constant of the window 10 (e.g., glass) is greater than that of air, and the dielectric constant of the sheet 20 is greater than that of the window 10. The wavelength of radio waves passing through the window 10 is shorter than that of radio waves in air, and the wavelength of radio waves passing through the sheet 20 is shorter than that of radio waves passing through the window 10. The reflection intensity of radio waves W in a predetermined band that pass through the window 10 and reach the sheet 20 is lower than the reflection intensity of radio waves W in a predetermined band that pass through the window 10 when either the first surface 11 or the second surface 12, or both the first surface 11 and the second surface 12, are in contact with air. For example, the reflection intensity of radio waves in a predetermined band that pass through the sheet 20 and reach the window 10 is lower than the reflection intensity of radio waves in a predetermined band that pass through the window 10 when either the first surface 11 or the second surface 12, or both the first surface 11 and the second surface 12 are in contact with air.

[0042] The predetermined band is, for example, a 5G radio wave band (for example, a millimeter wave band) or a 6G radio wave band (for example, a sub-terahertz wave band). In this embodiment, the intensity of the reflected wave that passes through the window 10, is reflected by the sheet 20 (the first sheet surface 21 or the second sheet surface 22), and travels from the window 10 toward the opposite side of the sheet 20 is lower than the intensity of the radio wave that passes through the window 10 and the sheet 20.

[0043] In this embodiment, the sheet 20 suppresses attenuation of the transmitted waves by canceling out the phases of the reflected waves and thereby attenuating the reflected waves. For example, the phase of the reflected wave W1 reflected at the first surface 11, the phase of the reflected wave W2 reflected at the first surface 21 of the sheet, and the phase of the reflected wave W3 reflected at the second surface 22 of the sheet cancel out each other, thereby reducing the intensity of the reflected wave traveling from the window 10 in the direction opposite to the sheet 20.

[0044] If the energy of the reflected wave traveling from the window 10 in the opposite direction to the sheet 20 is R and the energy of the transmitted wave traveling through the window 10 and the sheet 20 is T, then according to the law of conservation of energy, R + T = 1. As described above, when the intensity of the reflected wave traveling from the window 10 in the opposite direction to the sheet 20 decreases, the intensity of the transmitted wave W4 traveling through the window 10 and the sheet 20 increases. By attaching the sheet 20 containing a dielectric to the window 10, the intensity of the transmitted wave W4 traveling through the window 10 and the sheet 20 can be increased.

[0045] The thickness of the window 10 is d ｇ , the dielectric constant of the window 10 (e.g., glass) is ε ｇ , the thickness of the sheet 20 is d ａ , the dielectric constant of the sheet 20 is ε ａ When this is the case, d ａ and ε ａ By adjusting the value of , it becomes possible to shift the phase and intensity of the reflected waves W2 and W3, and it becomes possible to adjust the phase by the optical path difference of the reflected waves W1 to W3. ａ and ε ａ The value of may be adjusted.

[0046] In the window structure 1 according to this embodiment, at least one of the reflection intensity of radio waves W in a predetermined band that pass through the window 10 and reach the sheet 20 and the reflection intensity of radio waves in a predetermined band that pass through the sheet 20 and reach the window 10 is lower than the reflection intensity of radio waves in a predetermined band that pass through the window 10 when the first surface 11, the second surface 12, or both, of the window 10 are in contact with air. Because the reflection intensity of radio waves in the predetermined band is low, the intensity of radio waves (e.g., transmitted wave W4) that pass through the window 10 and the sheet 20 can be increased based on the law of conservation of energy regarding the reflection and transmission of radio waves. By suppressing the blocking and attenuation of radio waves and increasing the transmitted intensity of radio waves, the communication environment inside the building S can be stabilized.

[0047] Various modified examples of the window structure according to the present disclosure will be described. (a) of FIG. 6 is a cross-sectional view schematically illustrating a window structure 1A according to a first modified example. The window structure 1A has a pair of sheets 20A attached to both the first surface 11 and the second surface 12 of the window 10. The sheets 20A differ from the sheet 20 described above in that they include an adhesive layer 23. The sheets 20A can be used in place of the sheet 20. For example, the sheet 20A attached to the first surface 11 is the same as the sheet 20A attached to the second surface 12. However, the sheet 20A attached to the first surface 11 may be different from the sheet 20A attached to the second surface 12. At least one of the thickness and the dielectric constant of the sheet 20A attached to the first surface 11 may be different from at least one of the thickness and the dielectric constant of the sheet 20A attached to the second surface 12.

[0048] For example, before being attached to the window 10, the sheet 20A has a release paper adhered to the adhesive layer 23, and the release paper is peeled off, leaving the adhesive layer 23 attached to the window 10. In this case, the tape 30 described above may be unnecessary. The sheet 20A may have an adhesive layer made of an adhesive instead of the adhesive layer 23. In the window structure 1A, by attaching the sheet 20A to both the first surface 11 and the second surface 12 of the window 10, it is possible to increase the transmittance of radio waves compared to a case in which the sheet 20A is not attached to the window 10.

[0049] 6(b) is a cross-sectional view schematically illustrating a window structure 1B according to a second modified example. The window structure 1B has a sheet 20A attached to the first surface 11 of the window 10. In the window structure 1B, by attaching the sheet 20A to the first surface 11 of the window 10, it is possible to increase the transmittance of radio waves compared to a case in which the sheet 20A is not attached to the window 10. The sheet 20A may also be attached to the second surface 12.

[0050] Fig. 7(a) is a cross-sectional view schematically showing a window structure 1C according to a third modified example. The window structure 1C has two windows 10. The window structure 1C comprises a double-glazed window 40 having two windows 10 and a sheet 20 attached to at least one of the first surface 11 and the second surface 12 of the two windows 10. For example, an air layer is formed between the two windows 10. Fig. 7(a) is a schematic diagram showing a case where the sheet 20 is attached to the outside of the window 10 (for example, the side exposed to the outside air).

[0051] 7B is a cross-sectional view showing a window structure 1D according to a fourth modified example. In the window structure 1D, a sheet 20 is attached to the inside of the window 10 (e.g., the side that contacts the intermediate layer). In the window structures 1C and 1D, similar to the above-described window structure 1, the sheet 20 is attached to the second surface 12 of the window 10, thereby increasing the transmittance of radio waves compared to when the sheet 20 is not attached to the second surface 12. In the above-described window structures 1C and 1D, the sheet 20 may be attached to the first surface 11 of the window 10. The location where the sheet 20 is attached and the number of sheets 20 attached can be changed as appropriate.

[0052] 8A is a cross-sectional view showing a window structure 1E according to a fifth modified example. The window structure 1E includes two windows 10, a sheet 20, and a laminated glass interlayer 45. In the window structure 1E, a double-glazed window 40 includes the laminated glass interlayer 45. The laminated glass interlayer 45 is located between the two windows 10 and adheres closely to each of the two windows 10. In this way, the sheet 20 can also be applied to laminated glass.

[0053] 8(b) is a cross-sectional view showing a window structure 1F according to a sixth modified example. The window structure 1F has two windows 10, a sheet 20, and a heat-shielding layer 46. In the window structure 1F, the double-glazed window 40 is provided with the heat-shielding layer 46. The heat-shielding layer 46 is provided to suppress heat transmission into the double-glazed window 40.

[0054] The heat-shielding layer 46 is attached, for example, to the second surface 12 of the outdoor-facing window 10. However, the heat-shielding layer 46 may also be attached to the first surface 11 of the indoor-facing window 10, and the location where the heat-shielding layer 46 is attached is not particularly limited. The window structure 1F equipped with the heat-shielding layer 46 can increase the transmittance of radio waves in the building S, and the heat-shielding layer 46 suppresses heat passing through the double-glazed window 40. Therefore, it is possible to suppress heat and cold in the building S.

[0055] The embodiments and various modifications of the window structure and sheet according to the present disclosure have been described. However, the present disclosure is not limited to the above-described embodiments or various modifications, and may be further modified within the scope of the gist described in the claims. The structure, shape, size, material, number, and arrangement of each part of the window structure and sheet according to the present disclosure can be appropriately changed within the scope of the above-described gist.

[0056] Next, examples of the window structure and sheet according to the present disclosure will be described. The window structure and sheet according to the present disclosure are not limited to the contents of the following examples. As shown in FIG. 9 , radio wave intensity measurement tests were conducted for Examples 1 to 3 and Comparative Examples 1 and 2, which will be described later. The measurement device used in the radio wave intensity measurement tests included a turntable on which the window 10 was placed, a radio wave irradiator that irradiated radio waves onto the window 10, a radio wave receiver that received radio waves from the radio wave irradiator, and a measuring device that measured the intensity of the radio waves received by the radio wave receiver. Examples 1 to 3 and Comparative Examples 1 and 2 are as follows.

[0057] Example 1 Radio waves from a radio wave irradiator were transmitted through a window structure 1 having a sheet 20 attached to a window 10 from the window 10 side, and the intensity of the radio waves transmitted through the window structure 1 was measured using a measuring device. The following Samples 1, 2, and 3 were prepared as the sheet 20, and measurements of radio waves were performed on each of Samples 1 to 3. The distance from the radio wave irradiator to the window structure 1 and the distance from the window structure 1 to the radio wave receiver were approximately 100 cm. As shown in Table 1, Samples 1 to 3 were sheet-like samples formed to a thickness of approximately 200 μm from a homogeneous compound containing 55.7 vol% polystyrene (manufactured by Toyo Styrene Co., Ltd., product name "Toyo Styrol GP G100C") and 44.3 vol% barium titanate (manufactured by Kyoritsu Material Co., Ltd., product name "BT-SA"). Example 2 Radio waves from a radio wave irradiator were transmitted through a window structure 1 having a sheet 20 attached to a window 10 from the window 10 side, and the intensity of the radio waves transmitted through the window structure 1 was measured using a measuring device. The following Samples 4, 5, and 6 were prepared as the sheet 20, and measurements of radio waves were performed on each of Samples 4 to 6. The distance from the radio wave irradiator to the window structure 1 and the distance from the window structure 1 to the radio wave receiver were approximately 100 cm. As shown in Table 2, Samples 4 to 6 were sheet-like samples formed to a thickness of approximately 200 μm from a homogeneous compound containing 53.9 vol% polystyrene (manufactured by Toyo Styrene Co., Ltd., product name "Toyo Styrol GP G100C") and 46.1 vol% barium titanate (manufactured by Kyoritsu Material Co., Ltd., product name "BT-SA"). Example 3 Radio waves from a radio wave irradiator were transmitted through a window structure 1 having a sheet 20 attached to a window 10 from the window 10 side, and the intensity of the radio waves transmitted through the window structure 1 was measured using a measuring device. As the sheet 20, the following Samples 7, 8, and 9 were prepared, and measurements of radio waves were performed on each of Samples 7 to 9. As shown in Table 3, Samples 7 to 9 were sheet-like samples formed to a thickness of approximately 200 μm from a uniform compound of 46.0 vol% polystyrene (manufactured by Toyo Styrene Co., Ltd., product name "Toyo Styrol GP G100C") and 54.0 vol% barium titanate (manufactured by Kyoritsu Material Co., Ltd., product name "BT-SA"). (Comparative Example 1) With nothing placed on the turntable, the radio waves that passed through the air from the radio wave irradiator were received by the radio wave receiver, and the strength of the radio waves received by the radio wave receiver was measured using a measuring device. The distance from the radio wave irradiator to the radio wave receiver was approximately 200 cm. (Comparative Example 2) With only the window 10 placed on the turntable, the radio waves that passed through the window 10 were received by the radio wave receiver, and the strength of the radio waves received by the radio wave receiver was measured using a measuring device. The distance from the radio wave irradiator to the window 10 and the distance from the window 10 to the radio wave receiver were approximately 100 cm.

[0058] Fig. 10 is a graph showing the results of the radio wave intensity measurement test for Examples 1 to 3 and Comparative Examples 1 and 2. As shown in Fig. 10, in Examples 1 to 3 in which sheet 20 was attached to window 10, the intensity of the radio waves that penetrated was higher than in Comparative Example 2 in which only window 10 was used, and it was found that, depending on the frequency band of the radio waves, the intensity of the radio waves that penetrated was higher than in Comparative Example 1 in which only air was used.

[0059] When the radio wave band was 27.5 (GHz), the radio wave intensity of Comparative Example 1 was −31.2 (dB) and the radio wave intensity of Comparative Example 2 was −36.8 (dB). In contrast, the radio wave intensity of Example 1 was −32.7 (dB), the radio wave intensity of Example 2 was −32.6 (dB), and the radio wave intensity of Example 3 was −34.0 (dB), and it was found that the intensity of the transmitted radio waves was higher than that of Comparative Example 2.

[0060] When the radio wave band was 28.0 (GHz), the radio wave intensity of Comparative Example 1 was −31.5 (dB) and the radio wave intensity of Comparative Example 2 was −36.8 (dB). In contrast, the radio wave intensity of Example 1 was −32.0 (dB), the radio wave intensity of Example 2 was −31.4 (dB), and the radio wave intensity of Example 3 was −33.4 (dB), and it was found that the intensity of the transmitted radio waves was higher than that of Comparative Example 2.

[0061] A radio wave intensity measurement test was carried out in Examples 4 to 6 and Comparative Examples 3 and 4 to measure the intensity of radio waves in a predetermined band that pass through the sheet 20 and reach the window 10. The measuring device used in Examples 4 to 6 and Comparative Examples 3 and 4 is the same as the measuring device described above. Examples 4 to 6 and Comparative Examples 3 and 4 are as follows.

[0062] (Example 4) Radio waves from a radio wave irradiator were transmitted through a window structure 1 having a sheet 20 attached to a window 10 from the sheet 20 side, and the intensity of the radio waves transmitted through the window structure 1 was measured using a measuring device. This example is the same as Example 1, except that the radio waves were transmitted through the sheet 20 side. (Example 5) Radio waves from a radio wave irradiator were transmitted through a window structure 1 having a sheet 20 attached to a window 10 from the sheet 20 side, and the intensity of the radio waves transmitted through the window structure 1 was measured using a measuring device. This example is the same as Example 2, except that the radio waves were transmitted through the sheet 20 side. (Example 6) Radio waves from a radio wave irradiator were transmitted through a window structure 1 having a sheet 20 attached to a window 10 from the sheet 20 side, and the intensity of the radio waves transmitted through the window structure 1 was measured using a measuring device. This example is the same as Example 3, except that the radio waves were transmitted through the sheet 20 side. (Comparative Example 3) In Comparative Example 3, the radio wave intensity was measured under the same conditions as Comparative Example 1. (Comparative Example 4) In Comparative Example 4, the radio wave intensity was measured under the same conditions as Comparative Example 2.

[0063] Regarding the results of Examples 4 to 6 and Comparative Examples 4 and 5, when the radio wave band was 27.5 (GHz), the radio wave strength of Comparative Example 3 was −31.3 (dB) and the radio wave strength of Comparative Example 4 was −36.0 (dB). In contrast, the radio wave strength of Example 4 was −32.7 (dB), the radio wave strength of Example 5 was −32.7 (dB), and the radio wave strength of Example 6 was −34.2 (dB), and it was found that the strength of the transmitted radio waves was higher than that of Comparative Example 4.

[0064] When the radio wave band was 28.0 (GHz), the radio wave intensity of Comparative Example 3 was −31.4 (dB) and the radio wave intensity of Comparative Example 4 was −36.7 (dB). In contrast, the radio wave intensity of Example 4 was −31.8 (dB), the radio wave intensity of Example 5 was −31.6 (dB), and the radio wave intensity of Example 6 was −33.3 (dB), and it was found that the intensity of the transmitted radio waves was higher than that of Comparative Example 4.

[0065] As described above, in Examples 4 to 6 in which radio waves are incident from the sheet 20 side, it was found that the strength of the radio waves passing through the window structure can be increased, as in Examples 1 to 3 in which radio waves are incident from the window 10 side.

[0066] 1, 1A, 1B, 1C, 1D, 1E, 1F...window structure, 2...frame, 3...sash, 10...window, 11...first surface, 12...second surface, 20, 20A...sheet, 21...first surface of sheet, 22...second surface of sheet, 23...adhesive layer, 30...tape, 40...double-glazed window, 45...glass interlayer, 46...heat-shielding layer, S...building, W...radio wave, W1, W2, W3...reflected wave, W4...transmitted wave.

Claims

1. A window structure comprising: a window having a first surface and a second surface opposite to the first surface; and a sheet affixed to at least one of the first and second surfaces of the window and containing a matrix resin and an inorganic filler, wherein at least one of the reflection intensity of radio waves in a predetermined band that pass through the window and reach the sheet and the reflection intensity of radio waves in the predetermined band that pass through the sheet and reach the window is lower than the reflection intensity of radio waves in the predetermined band that pass through the window when either the first surface or the second surface, or both the first surface and the second surface, are in contact with air, and the matrix resin is a thermoplastic resin or a thermosetting resin.

2. The window structure according to claim 1, wherein the matrix resin comprises at least one of polystyrene and polyethylene.

3. The window structure according to claim 1 or 2, wherein the sheet contains 1 to 90% by volume of the inorganic filler.

4. The window structure according to any one of claims 1 to 3, wherein the inorganic filler is at least one selected from the group consisting of barium titanate, calcium titanate, strontium titanate, and titanium-strontium-zirconia.

5. A window structure according to any one of claims 1 to 4, wherein the particle size of the inorganic filler is 0.001 to 100 μm.

6. A window structure according to any one of claims 1 to 5, comprising a double-glazed window having two of the windows and the sheet attached to at least one of the first surface and the second surface of the two windows.

7. The window construction of claim 6, wherein the double-glazed window comprises a laminated glass interlayer.

8. The window structure according to claim 6, wherein the double-glazed window comprises a heat-shielding layer.

9. A window structure according to any one of claims 1 to 8, wherein the periphery of the sheet is fixed to the window with tape, and the sheet is in close contact with the window.

10. A window structure according to any one of claims 1 to 9, wherein the sheet comprises at least one of a pressure-sensitive adhesive layer and an adhesive layer.

11. A window structure according to any one of claims 1 to 10, wherein the sheet is embossed.

12. A sheet to be attached to at least one of a first surface and a second surface opposite to the first surface of a window, the sheet comprising a matrix resin and an inorganic filler, wherein at least one of the reflection intensity of radio waves in a predetermined band that pass through the window and reach the sheet and the reflection intensity of radio waves in the predetermined band that pass through the sheet and reach the window is lower than the reflection intensity of radio waves in the predetermined band that pass through the window when either the first surface or the second surface, or both the first surface and the second surface, are in contact with air.

Images