Radio wave reflection device

Abstract

A radio wave reflection device according to the present invention has: a radio wave reflection plate that has a radio wave reflection surface at which are arranged a plurality of reflection elements that have a patch electrode and a common electrode; and a housing that houses the radio wave reflection plate. The housing has a heat insulation structure, and at least a region that covers the radio wave reflection surface of the radio wave reflection plate is formed from a dielectric material. The housing has an inner shell and an outer shell that is positioned outside the inner shell. The housing may also have a heat insulation layer that is in a vacuum state between the inner shell and the outer shell.

Description

radio wave reflector

[0001] The present invention relates to a radio wave reflecting device.

[0002] Radio wave reflecting devices are installed outdoors to deliver radio waves to areas (dead zones) where radio waves are difficult to reach, such as the valleys between high-rise buildings. Examples of radio wave reflecting devices include a configuration in which a main array element (dipole element), a subarray element (parasitic element), and a common electrode (ground electrode) are arranged with a dielectric substrate sandwiched between them, with the subarray element being disposed close to the main array element (Patent Document 1), and a configuration in which the array element and the common electrode (ground electrode) sandwich a dielectric substrate, with the common electrode having a periodic loop shape (Patent Document 2).

[0003] JP 2011-019021 A JP 2010-226695 A

[0004] A dielectric substrate is used in radio wave reflectors, but if the portion corresponding to this dielectric substrate is replaced with a liquid crystal layer, the dielectric anisotropy of the liquid crystal material can be utilized, making it possible to vary the directionality of the reflected waves. Radio wave reflectors using liquid crystal materials have a configuration in which reflecting elements are arranged in a matrix, similar to a planar array antenna with an array of patches. Radio wave reflectors control the direction of radio wave reflection by changing the dielectric constant of the liquid crystal layer that forms each reflecting element by applying a voltage between the electrodes.

[0005] The liquid crystal layer on the dielectric substrate is sensitive to temperature, and the liquid crystal crystallizes or becomes isotropic when the temperature exceeds a predetermined range. If the temperature environment in which the radio wave reflecting device is installed deviates from the operating range of the liquid crystal, the problem arises that the radio wave reflection direction cannot be controlled to the desired direction. Therefore, radio wave reflecting devices are required to be durable against temperature environments.

[0006] In view of the above problems, one object of one embodiment of the present invention is to provide a radio wave reflecting device that has improved resistance to the temperature environment in which the radio wave reflecting device is installed.

[0007] A radio wave reflection device according to one embodiment of the present invention comprises a radio wave reflection plate having a radio wave reflection surface on which a plurality of reflection elements each having a patch electrode and a common electrode are arranged, and a housing incorporating the radio wave reflection plate, wherein the housing has a heat-insulating structure and at least the area covering the radio wave reflection surface of the radio wave reflection plate is formed from a dielectric material.

[0008] 1 shows an end view of a radio wave reflecting device according to one embodiment of the present invention; FIG. 2 shows a plan view of a reflecting element used in a radio wave reflecting device according to one embodiment of the present invention; FIG. 3 shows an end view of a reflecting element used in a radio wave reflecting device according to one embodiment of the present invention; FIG. 4 shows a state in which the reflecting element used in a radio wave reflecting device according to one embodiment of the present invention is operating, showing a state in which no voltage is applied between the patch electrode and the common electrode; FIG. 5 shows a state in which the reflecting element used in a radio wave reflecting device according to one embodiment of the present invention is operating, showing a state in which a voltage is applied between the patch electrode and the common electrode; FIG. 6 shows the configuration of a radio wave reflecting device according to one embodiment of the present invention; FIG. 7 shows a schematic diagram illustrating how the direction of travel of a reflected wave is changed by a radio wave reflecting device according to one embodiment of the present invention; FIG. 8 shows the configuration of a radio wave reflecting device according to one embodiment of the present invention; FIG. 9 shows a plan view of a reflecting element in a radio wave reflecting device according to one embodiment of the present invention; FIG. 10 shows an end view of a radio wave reflecting device according to one embodiment of the present invention; FIG. 11 shows an end view of a radio wave reflecting device according to one embodiment of the present invention;

[0009] Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the present invention can be implemented in many different forms, and should not be construed as being limited to the description of the following exemplary embodiments. For clarity of explanation, the drawings may show the width, thickness, shape, etc. of each part schematically compared to the actual form. However, these are merely examples and are not intended to limit the interpretation of the present invention. Furthermore, in this specification and each drawing, elements similar to those previously described with reference to the previous drawings are designated by the same reference numerals (or reference numerals with a, b, etc. suffixed thereto), and detailed descriptions may be omitted as appropriate. Furthermore, the letters "first" and "second" attached to each element are convenient labels used to distinguish each element and have no further meaning unless otherwise specified.

[0010] In this specification, when a component or region is referred to as being "on (or under)" another component or region, unless otherwise specified, this includes not only the case where it is directly above (or directly under) the other component or region, but also the case where it is above (or under) the other component or region, i.e., the case where another component is included between the component or region and above (or under) the other component or region.

[0011] In this specification, the radio wave reflecting device (reflecting device) is also called an IRS (Intelligent Reflecting Surface).

[0012] First Embodiment With reference to FIG. 1, the configuration of a radio wave reflecting device 10 according to one embodiment of the present invention will be described.

[0013] 1 is an end view of a radio wave reflecting device 10 according to one embodiment of the present invention. The radio wave reflecting device 10 includes a radio wave reflecting plate 100 and a housing 200. The radio wave reflecting device 10 may also include a radiation plate 202, a protective portion 204, and a fixed portion 206.

[0014] 1. Housing The housing 200 has a storage space 208 capable of storing the radio wave reflector 100. The radio wave reflector 100 is disposed in the storage space 208. As shown in FIG. 1 , the housing 200 is structured to cover the entire radio wave reflector 100. The housing 200 has a structure that allows radio waves propagating through external space to pass through so that the radio waves are incident on the radio wave reflector 100 stored in the storage space 208. The housing 200 has a first surface 200-1 on the side through which the radio waves pass, and a second surface 200-2 opposite the first surface 200-1. For example, the first surface 200-1 of the housing 200 is preferably formed from a dielectric material so as to transmit radio waves and suppress attenuation. Examples of dielectric materials that can be used include inorganic insulating materials such as glass and ceramic, and resin materials such as acrylic and polycarbonate. The second surface 200-2 may be formed from a metal so that the housing 200 maintains a sturdy structure. Of course, both first surface 200-1 and second surface 200-2 may be formed of a dielectric material. There are no limitations on the structure of housing 200, and a dielectric window may be provided in a part (the part corresponding to first surface 200-1) of a box-shaped structure formed of steel material such as metal.

[0015] The housing 200 has a heat-insulating structure. A heat-insulating layer 210 is provided over the entire housing 200. As shown in FIG. 1 , the heat-insulating layer 210 is arranged so as to cover the radio wave reflector 100. By covering the radio wave reflector 100 with the heat-insulating layer 210, the housing 200 can prevent heat from the outside air temperature from being transmitted into the housing 200, thereby exhibiting a heat-insulating effect. The housing 200 can store the radio wave reflector 100 in a storage space 208 that is insulated from the outside air (atmospheric space).

[0016] The thermal insulation structure of the housing 200 is formed by an outer shell 212 on the outside of the housing 200, an inner shell 214 on the inside, and a gap between the outer shell 212 and the inner shell 214. In the outer shell 212, a first surface 212-1 is disposed on the side through which radio waves pass, and a second surface 212-2 is disposed on the surface opposite the first surface 212-1. In the inner shell 214, a first surface 214-1 is disposed on the side through which radio waves pass, and a second surface 214-2 is disposed on the surface opposite the first surface 212-1. The inner shell 214 and the outer shell 212 are integrated by joining their outer ends. By joining the inner shell 214 and the outer shell 212, a sealed space 216 is formed between the inner shell 214 and the outer shell 212. A vacuum state can be created in the space 216 between the inner shell 214 and the outer shell 212. The space 216 can function as a thermal insulation layer 210. The pressure of the insulating layer 210 can be set to a pressure lower than atmospheric pressure. By creating a vacuum in the space between the inner shell 214 and the outer shell 212, a vacuum insulating structure can be adopted.

[0017] An opening 218-1 is provided in the housing 200. The opening 218-1 can penetrate the outer shell 212. The opening 218-1 can function as an exhaust port for exhausting the space 216. The outer shell 212 is provided with a sealing portion 220-1 that seals the opening 218-1 to keep the space 216 sealed. While FIG. 1 shows an example in which the opening 218-1 functioning as an exhaust port is provided in the outer shell 212, it is sufficient that the opening 218-1 is provided in at least one of the outer shell 212 and the inner shell 214. The sealing portion 220 may be made of a sealing material such as resin, or the opening 218-1 may be sealed using the same material as the housing 200. For example, if glass is used for the housing 200, the opening 218-1 may be sealed with glass to form the sealing portion 220-1.

[0018] The heat insulating layer 210 may be formed using a heat insulating material that transmits radio waves, other than being formed in a vacuum state as described above. The heat insulating layer can be formed by filling a heat insulating material between the outer shell 212 and the inner shell 214. For example, a urethane foam material can be used as the heat insulating material that transmits radio waves.

[0019] The insulating layer 210 may be formed using a gas with low thermal conductivity. The insulating layer 210 may be formed by filling the space 216 between the outer shell 212 and the inner shell 214 with a gas with low thermal conductivity. When filling the space 216 with a gas with low thermal conductivity, the opening 218-1 can function as a filling port. Examples of the gas with low thermal conductivity that can be used include argon gas, krypton gas, and air. When air is used as the gas with low thermal conductivity, it is preferable to use dry air.

[0020] The inner shell 214 may have an opening 222. The outer shell 212 may have an opening 224 overlapping the opening 222 of the inner shell 214. The opening 222 of the inner shell 214 and the opening 224 of the outer shell 212 form an input port 225 of the housing 200. The outer shell 212 and the inner shell 214 are joined at the input port 225 of the housing 200, so that the space 216 of the thermal insulating layer 210 can be kept sealed. The input port 225 of the housing 200 is an opening for installing the radio wave reflector 100 inside the housing 200. In the thickness 100T direction of the radio wave reflector 100, the length L of the opening 222 of the inner shell 214 and the length 224L of the opening 224 of the outer shell 212 are preferably greater than the thickness 100T of the radio wave reflector 100 and less than the depth 200H of the housing 200.

[0021] The housing 200 can have a sealing portion 220-2 that seals the input port 225. By sealing the input port 225 with the sealing portion 220-2, the air or gas filled in the housing 200 or the storage space 208 does not leak out of the housing 200, and the temperature and humidity inside the housing 200 or the storage space 208 can be maintained. Alternatively, by sealing the input port 225 with the sealing portion 220-2, outside air does not enter the housing 200 or the storage space 208, and the temperature and humidity inside the housing 200 or the storage space 208 can be maintained. The sealing portion 220 can be made of a resin such as ABS resin or silicone rubber. Alternatively, the sealing portion 220 can be made of a lid made of the same material as the housing 200, and the joint between the lid and the housing 200 can be made of the above-mentioned resin or the like.

[0022] 2. Radiation Plate The radiation plate 202 can suppress radiant heat from the housing 200. The radio wave reflecting device 10 can have a radiation plate 202 facing the second surface 200-2 of the housing 200. The radiating plate 202 can be provided in contact with the housing 200. The radiating plate 202 may be provided on the housing 200 via an adhesive layer using an adhesive or the like with high thermal conductivity. As shown in FIG. 1 , the radiating plate 202 is arranged facing the second surface 200-2 of the housing 200. The radiating plate 202 may be arranged in contact with the second surface 200-2 of the housing 200. The radiating plate 202 can be arranged facing the second surface 212-2 of the outer shell 212. The radiating plate 202 can be arranged in contact with the second surface 212-2 of the outer shell 212. 1, the radiation plate 202 is provided so as to cover the entire second surface 200-2 of the housing 200, but it is sufficient that the radiation plate 202 is provided on at least a portion of the second surface 200-2 of the housing 200. The radiation plate 202 may be made of a metal or a thermally conductive resin having high thermal conductivity. For example, the radiation plate 202 may be made of a resin such as silicon or acrylic with copper, aluminum, or a metal filler dispersed therein.

[0023] The housing 200 may be provided with through-holes 226 that penetrate the outer shell 212 and the inner shell 214. Wiring that connects the radio wave reflector 100 to a power supply, a drive board, and the like installed outside the housing 200 can be passed through the through-holes 226. The through-holes 226 are formed in the outer shell 212 and the inner shell 214 to prevent the space between the outer shell 212 and the inner shell 214 from being exposed to the outside air. The through-holes 226 are formed by side walls that connect the outer shell 212 and the inner shell 214. When a radiation plate 202 is provided in the radio wave reflecting device 10, the through-holes 226 can penetrate the radiation plate 202 as well as the outer shell 212 and the inner shell 214. A protective portion 204 that protects the wiring connected to the radio wave reflector 100 is disposed in the through-hole 226.

[0024] 3. Protective Section The protective section 204 protects the cable 228 that connects the radio wave reflector 100 to an external power source or the like, and allows the cable 228 to pass from the inside to the outside of the housing 200. The protective section 204 is provided to cover the cable 228. The cable 228 is an FPC that is electrically connected to a terminal section 126 of the radio wave reflector 100, which will be described later, or a cable that can be connected to an FPC. The cable 228 can extend from the inside to the outside of the housing 200 via the protective section 204. It is preferable that the protective section 204 fills the space through which the cable 228 passes so that air or gas filled in the housing 200 or the storage space 208 does not leak out of the housing 200.

[0025] In addition to passing the cable 228 through the protective section 204, the protective section 204 can also support the radio wave reflector 100 and fix it to the housing 200. The protective section 204 is arranged so as to cover at least a portion of the peripheral area 122 described below. The protective section 204 extends from the surface that reflects radio waves (radio wave reflecting surface) to the back surface and can pass through the through-hole 226. The protective section 204 passes through the through-hole 226 and is fixed to the housing 200. The protective section 204 may be fixed to the housing 200 by connecting members such as bolts and nuts in addition to the through-hole 226. In this case, a plurality of the above-mentioned through-holes 226 may be provided in the housing 200, and the connecting members may be passed through the through-holes 226. The protective section 204 can also lead the cable 228 to the outside of the housing 200 through the sealing section 220-2.

[0026] 4. The fixed portion housing 200 can be fixed to a building on which the radio wave reflecting device 10 is installed by the fixed portion 206. As shown in FIG. 1 , the housing 200 is fixed to a pillar 1000 of a building by the fixed portion 206. The fixed portion 206 extends from the housing 200 toward the building and can be fixed to the building by a fastener (not shown) or the like, thereby fixing the housing 200 to the building. In FIG. 1 , one fixed portion 206 is connected to the housing 200 and the pillar 1000, but multiple fixed portions 206 may be connected to the housing 200 and the pillar 1000. When the radiation plate 202 is provided in the radio wave reflecting device 10 as shown in FIG. 1 , the fixed portion 206 can be connected to the radiation plate 202 connected to the housing 200 to fix the housing 200 to the building.

[0027] 2 to 5 show the reflecting element 102 used in the radio wave reflecting plate 100 according to one embodiment of the present invention. Fig. 2 shows a plan view of the reflecting element 102 as seen from above (the side where radio waves are incident), and Figs. 3 to 5 show end views between A1 and A2 shown in the plan view.

[0028] 2 and 3, the reflective element 102 includes a dielectric substrate 104, a counter substrate 106, a patch electrode 108, a common electrode 110, a first alignment film 112a, a second alignment film 112b, and a liquid crystal layer 114. Within the reflective element 102, the dielectric substrate 104 can also be considered as a single layer, i.e., a dielectric layer. The patch electrode 108 is provided on the dielectric substrate 104, and the common electrode 110 is provided on the counter substrate 106. The common electrode 110 is disposed on the rear side of the patch electrode 108. A first alignment film 112a is provided on the dielectric substrate 104 to cover the patch electrode 108, and a second alignment film 112b is provided on the counter substrate 106 to cover the common electrode 110. The patch electrode 108 and the common electrode 110 are disposed opposite each other, with a liquid crystal layer 114 disposed between them. A first alignment film 112 a is interposed between the patch electrode 108 and the liquid crystal layer 114 , and a second alignment film 112 b is interposed between the common electrode 110 and the liquid crystal layer 114 .

[0029] The patch electrode 108 preferably has a shape that is symmetrical with respect to the vertically and horizontally polarized waves of the incident radio wave, and has a square or circular shape in a planar view. Figure 2 shows a case where the patch electrode 108 is square in a planar view. The shape of the common electrode 110 is not particularly limited, and it has a shape that extends over substantially the entire surface of the opposing substrate 106 so as to have a larger area than the patch electrode 108. The material for forming the patch electrode 108 and the common electrode 110 is not particularly limited, and they may be formed using conductive metals or metal oxides. A first wiring 118 may be provided on the dielectric substrate 104. The first wiring 118 is connected to the patch electrode 108. The first wiring 118 can be used to apply a control signal to the patch electrode 108. Furthermore, when multiple reflecting elements are arranged, the first wiring 118 can be used to connect a patch electrode to an adjacent patch electrode.

[0030] Although not shown in FIGS. 2 and 3 , the dielectric substrate 104 and the counter substrate 106 are bonded together with a sealant. The dielectric substrate 104 and the counter substrate 106 are disposed opposite each other to form a storage space, and the liquid crystal layer 114 is provided within the area surrounded by the sealant. The liquid crystal layer 114 is provided to fill the storage space between the dielectric substrate 104 and the counter substrate 106. The gap between the dielectric substrate 104 and the counter substrate 106 is 20 to 100 μm, for example, 50 μm. Because the patch electrode 108, the common electrode 110, the first alignment film 112 a, and the second alignment film 112 b are provided between the dielectric substrate 104 and the counter substrate 106, the thickness of the liquid crystal layer 114 is precisely the gap between the first alignment film 112 a and the second alignment film 112 b provided on the dielectric substrate 104 and the counter substrate 106, respectively. Although not shown in FIG. 3, a spacer may be provided between the dielectric substrate 104 and the opposing substrate 106 to maintain a constant gap therebetween.

[0031] A control signal that controls the orientation of liquid crystal molecules in the liquid crystal layer 114 is applied to the patch electrode 108. The control signal is a DC voltage signal or a polarity inversion signal in which positive and negative DC voltages alternate. The common electrode 110 is grounded or receives a voltage at an intermediate level of the polarity inversion signal. Application of the control signal to the patch electrode 108 changes the orientation state of the liquid crystal molecules contained in the liquid crystal layer 114. A liquid crystal material having dielectric anisotropy is used for the liquid crystal layer 114. For example, nematic liquid crystal, smectic liquid crystal, cholesteric liquid crystal, or discotic liquid crystal can be used for the liquid crystal layer 114. The dielectric constant of the liquid crystal layer 114 with dielectric anisotropy changes depending on the change in the orientation state of the liquid crystal molecules. The reflective element 102 can change the dielectric constant of the liquid crystal layer 114 by applying a control signal to the patch electrode 108, thereby delaying the phase of the reflected wave when reflecting radio waves.

[0032] The frequency bands of radio waves reflected by the reflective element 102 are the very high frequency (VHF) band, the ultra high frequency (UHF) band, the super high frequency (SHF) band, the submillimeter wave (THF) band, and the extra high frequency (EHF) band. The liquid crystal molecules in the liquid crystal layer 114 change their orientation in response to a control signal applied to the patch electrode 108, but the orientation hardly changes with the frequency of the radio waves irradiated onto the patch electrode 108. Therefore, the reflective element 102 can control the phase of the reflected radio waves without being affected by the radio waves themselves.

[0033] FIG. 4 shows a state (referred to as the "first state") in which no voltage is applied between the patch electrode 108 and the common electrode 110. FIG. 4 also shows a case in which the first alignment film 112a and the second alignment film 112b are horizontal alignment films. In the first state, the long axes of the liquid crystal molecules 116 are aligned horizontally relative to the surfaces of the patch electrode 108 and the common electrode 110 by the first alignment film 112a and the second alignment film 112b. FIG. 5 shows a state (referred to as the "second state") in which a control signal (voltage signal) is applied to the patch electrode 108. In the second state, the liquid crystal molecules 116 are oriented with their long axes perpendicular to the surfaces of the patch electrode 108 and the common electrode 110 due to the action of an electric field. The angle at which the long axes of the liquid crystal molecules 116 are aligned can be set to a direction intermediate between the horizontal and vertical directions depending on the magnitude of the control signal applied to the patch electrode 108 (the magnitude of the voltage Vn (n is a natural number) between the common electrode and the patch electrode).

[0034] When the liquid crystal molecules 116 have positive dielectric anisotropy, the dielectric constant is greater in the second state than in the first state. When the liquid crystal molecules 116 have negative dielectric anisotropy, the apparent dielectric constant is smaller in the second state than in the first state. The liquid crystal layer 114, which has dielectric anisotropy, can also be considered a variable dielectric layer. The reflective element 102 can control the phase of the reflected wave to delay (or not delay) by utilizing the dielectric anisotropy of the liquid crystal layer 114.

[0035] The reflecting element 102 is used as a radio wave reflector that reflects radio waves in a predetermined direction. It is preferable that the reflecting element 102 attenuates the amplitude of the reflected radio waves as little as possible. As is clear from the structure shown in Figure 3, when radio waves propagating through the air are reflected by the reflecting element 102, the radio waves pass through the dielectric substrate 104 twice. The dielectric substrate 104 is formed of a dielectric material such as glass or resin.

[0036] Next, the structure of a radio wave reflector in which reflecting elements are integrated will be described.

[0037] 5-2. Radio Wave Reflecting Device A (Single-Axis Reflection Control) FIG. 6 shows the configuration of the radio wave reflecting plate 100 of the radio wave reflecting device 10 according to one embodiment of the present invention.

[0038] The radio wave reflector 100 is disposed surrounded by the housing 200. The radio wave reflector 100 can be disposed inside the housing 200 through an input port 225 of the housing 200. The width 225W of the input port 225 only needs to be larger than the width 100W of the radio wave reflector 100. As shown in Fig. 6, the widths of the opening 222 of the inner shell 214 and the opening 224 of the outer shell 212 can be larger than the width 100W of the radio wave reflector 100a and smaller than the width 200W of the housing 200.

[0039] The radio wave reflector 100a is composed of a plurality of reflecting elements 102. The plurality of reflecting elements 102 are arranged, for example, in a column direction (the X-axis direction shown in FIG. 6 ) and a row direction (the Y-axis direction shown in FIG. 6 ) intersecting the column direction. The reflecting elements 102 are arranged so that their patch electrodes 108 face the plane of incidence of the radio waves. The radio wave reflector 100a is flat, and the plurality of patch electrodes 108 are arranged in a matrix on the surface of this flat plate.

[0040] The radio wave reflector 100a has a structure in which multiple reflecting elements 102 are integrated on a single dielectric substrate 104. As shown in FIG. 6 , the radio wave reflector 100 has a structure in which a dielectric substrate 104 on which multiple patch electrodes 108 are arranged and a counter substrate 106 on which a common electrode 110 is provided are stacked, with a liquid crystal layer (not shown) provided between the two substrates. The radio wave reflecting surface 120 is formed in the area where the multiple patch electrodes 108 and the common electrode 110 overlap. The cross-sectional structure of the radio wave reflector 100, in terms of each patch electrode 108, is the same as the structure of the reflecting element 102 shown in FIG. 3 . The dielectric substrate 104 and the counter substrate 106 are bonded together with a sealant 128, and a liquid crystal layer (not shown) is provided in the area inside the sealant 128.

[0041] The dielectric substrate 104 has a region facing the opposing substrate 106, as well as a peripheral region 122 extending outward from the opposing substrate 106. A first drive circuit 124 and a terminal section 126 are provided in the peripheral region 122. The first drive circuit 124 outputs a control signal to the patch electrode 108. The terminal section 126 is a region for forming a connection with an external circuit, and is connected to, for example, a flexible printed circuit board (FPC) (not shown). A signal for controlling the first drive circuit 124 is input to the terminal section 126.

[0042] The peripheral region 122 in which the first drive circuit 124 and the terminal portion 126 are provided may be covered by a protective portion 204 .

[0043] As described above, a plurality of patch electrodes 108 are arranged in the column direction (X-axis direction) and row direction (Y-axis direction) on the dielectric substrate 104. Furthermore, a plurality of first wirings 118 extending in the row direction (Y-axis direction) are arranged on the dielectric substrate 104. Each of the plurality of first wirings 118 is electrically connected to a plurality of patch electrodes 108 arranged in the row direction (Y-axis direction). In other words, the plurality of patch electrodes 108 arranged in the row direction (Y-axis direction) are connected by the first wirings 118. The radio wave reflector 100 has a configuration in which a plurality of patch electrode arrays connected by the first wirings 118 are arranged in a row in the column direction (X-axis direction).

[0044] The plurality of first wirings 118 arranged on the radio wave reflecting plate 100 extend into the peripheral region 122 and are connected to a first driving circuit 124. The first driving circuit 124 is capable of outputting control signals of different voltage levels to each of the plurality of first wirings 118. As a result, in the radio wave reflecting plate 100, a control signal is applied to each of the plurality of patch electrodes 108 arranged in the column direction (X-axis direction) and row direction (Y-axis direction) for each column (each patch electrode 108 arranged in the row direction (Y-axis direction)).

[0045] The radio wave reflector 100a is applied with a control signal for each set of the plurality of patch electrodes 108 arranged in the row direction (Y-axis direction), thereby controlling the reflection direction of the reflected waves of the radio waves incident on the radio wave reflecting surface 120. In other words, the radio wave reflector 100a can control the propagation direction of the reflected waves of the radio waves irradiated onto the radio wave reflecting surface 120 in the left-right direction in the drawing, centered on a reflection axis VR parallel to the row direction (Y-axis direction).

[0046] FIG. 7 shows a schematic diagram illustrating how the direction of propagation of a reflected wave changes depending on the two reflecting elements 102. When radio waves are incident on the reflecting elements 102a and 102b with the same phase, different control signals (V1 ≠ V2) are applied to the reflecting elements 102a and 102b, resulting in a larger phase change in the reflected wave from the reflecting element 102b than from the reflecting element 102a. As a result, the phase of the reflected wave R1 reflected from the reflecting element 102a differs from the phase of the reflected wave R2 reflected from the reflecting element 102b (in FIG. 7, the phase of the reflected wave R2 leads the phase of the reflected wave R1), and the apparent direction of propagation of the reflected wave changes obliquely. In this way, the radio wave reflector 100 has a surface (radio wave reflecting surface 120) that reflects radio waves using an arrangement of multiple reflecting elements 102.

[0047] This principle can be applied to the radio wave reflector 100a shown in FIG. 6, and for example, by controlling the amount of phase change by the reflecting elements for each row, the reflection direction can be controlled in one axis direction.

[0048] 5-3. Radio wave reflecting device B (two-axis reflection control) The radio wave reflector 100a shown in Fig. 6 has a single reflection axis VR, so the reflection angle can be controlled in the direction around the reflection axis VR as the axis of rotation. In contrast, this embodiment shows an example of a radio wave reflector 100b that can perform two-axis reflection control. The following explanation will focus on the differences from the radio wave reflector 100a.

[0049] The radio wave reflector 100b has a plurality of second wirings 132 extending in the column direction (X-axis direction). The plurality of first wirings 118 and the plurality of second wirings 132 are arranged to intersect with an insulating layer (not shown) sandwiched therebetween. The plurality of first wirings 118 are connected to a first drive circuit 124, and the plurality of second wirings 132 are connected to a second drive circuit 130. The second drive circuit 130 outputs a scanning signal.

[0050] 9 shows an enlarged view of an arrangement 102m of four patch electrodes 108 and two first wirings 118 and second wirings 132. Each of the four patch electrodes 108 is provided with a switching element 134. The switching (on and off) of the switching element 134 is controlled by a scanning signal applied to the second wiring 132. When the switching element 134 is turned on, the patch electrode 108 is electrically connected to the first wiring 118 and a control signal is applied to it. The switching element 134 is formed of, for example, a thin-film transistor. With this configuration, it is possible to select a plurality of patch electrodes 108 arranged in the column direction (X-axis direction) for each row and apply control signals of different voltage levels to each row.

[0051] 8 can control the direction of travel of the reflected waves of radio waves irradiated onto the radio wave reflecting surface 120 in the left-right direction of the drawing, centered on a reflection axis VR parallel to the row direction (Y-axis direction), and can also control the direction of travel of the reflected waves in the up-down direction of the drawing, centered on a reflection axis HR parallel to the column direction (X-axis direction). In other words, since the radio wave reflector 100b has a reflection axis VR parallel to the row direction (Y-axis direction) and a reflection axis HR parallel to the column direction (X-axis direction), it can control the reflection angle in the direction about the reflection axis VR as the rotation axis and in the direction about the reflection axis HR as the rotation axis.

[0052] This principle can be applied to the radio wave reflector 100b shown in Figure 8, and for example, by independently controlling the amount of phase change by the reflecting elements in both columns and rows, the reflection direction can be controlled in both uniaxial and biaxial directions.

[0053] 9 shows an example of the cross-sectional structure of a reflective element 102 in which a switching element 134 is connected to a patch electrode 108. The switching element 134 is provided on a dielectric substrate 104. The switching element 134 is a transistor and has a stacked structure of a first gate electrode 138, a first gate insulating layer 140, a semiconductor layer 142, a second gate insulating layer 146, and a second gate electrode 148. An undercoat layer 136 may be provided between the first gate electrode 138 and the dielectric substrate 104. A first wiring 118 is provided between the first gate insulating layer 140 and the second gate insulating layer 146. The first wiring 118 is provided so as to be in contact with the semiconductor layer 142. A first connection wiring 144 is provided in the same layer as the conductive layer that forms the first wiring 118. The first connection wiring 144 is provided so as to be in contact with the semiconductor layer 142. The connection structure of the first wiring 118 and the first connection wiring 144 to the semiconductor layer 142 shows a structure in which one wiring is connected to the source of the transistor and the other wiring is connected to the drain.

[0054] A first interlayer insulating layer 150 is provided to cover the switching element 134. A second wiring 132 is provided on the first interlayer insulating layer 150. The second wiring 132 is connected to the second gate electrode 148 through a contact hole formed in the first interlayer insulating layer 150. Although not shown, the first gate electrode 138 and the second gate electrode 148 are electrically connected to each other in a region that does not overlap with the semiconductor layer 142. A second connection wiring 152 is provided on the first interlayer insulating layer 150 and is made of the same conductive layer as the second wiring 132. The second connection wiring 152 is connected to the first connection wiring 144 through a contact hole formed in the first interlayer insulating layer 150.

[0055] A second interlayer insulating layer 154 is provided to cover the second wiring 132 and the second connection wiring 152. Furthermore, a planarizing layer 156 is provided to fill in the step of the switching element 134. By providing the planarizing layer 156, the patch electrode 108 can be formed without being affected by the arrangement of the switching element 134. A passivation layer 158 is provided on the flat surface of the planarizing layer 156. The patch electrode 108 is provided on the passivation layer 158. The patch electrode 108 is connected to the second connection wiring 152 via a contact hole that penetrates the passivation layer 158, the planarizing layer 156, and the second interlayer insulating layer 154. A first alignment film 112a is provided on the patch electrode 108.

[0056] The counter substrate 106 is provided with a common electrode 110 and a second alignment film 112b, as in FIG. 2 . The surface of the dielectric substrate 104 on which the switching elements 134 and patch electrodes 108 are provided faces the surface of the counter substrate on which the common electrode 110 is provided, and a liquid crystal layer 114 is provided therebetween. The thickness T of the dielectric substrate 104 can be defined as the length from the surface of the patch electrode 108 on the liquid crystal layer 114 side to the surface of the dielectric substrate 104 opposite the surface on which the patch electrode 108 is provided. In this case, the thickness of at least one insulating layer (undercoat layer 136, first gate insulating layer 140, second gate insulating layer 146, first interlayer insulating layer 150, second interlayer insulating layer 154, planarizing layer 156, passivation layer 158) between the patch electrode 108 and the dielectric substrate 104 can be taken into consideration.

[0057] The layers formed on the dielectric substrate 104 are formed using the following materials. The undercoat layer 136 is formed, for example, of a silicon oxide film. The first gate insulating layer 140 and the second gate insulating layer 146 are formed, for example, of a silicon oxide film or a stacked structure of a silicon oxide film and a silicon nitride film. The semiconductor layer is formed of a silicon semiconductor such as amorphous silicon or polycrystalline silicon, or an oxide semiconductor including a metal oxide such as indium oxide, zinc oxide, or gallium oxide. The first gate electrode 138 and the second gate electrode 148 may be formed, for example, of molybdenum (Mo), tungsten (W), or an alloy thereof. The first wiring 118, the second wiring 132, the first connection wiring 144, and the second connection wiring 152 are formed using a metal material such as titanium (Ti), aluminum (Al), or molybdenum (Mo). For example, they may be formed as a stacked structure of titanium (Ti), aluminum (Al), and titanium (Ti), or a stacked structure of molybdenum (Mo), aluminum (Al), and molybdenum (Mo). The planarization layer 156 is made of a resin material such as acrylic or polyimide. The passivation layer 158 is made of, for example, a silicon nitride film. The patch electrode 108 and the common electrode 110 are made of a metal film such as aluminum (Al) or copper (Cu).

[0058] 9 , by connecting the second wiring 132 to the gate of a transistor used as a switching element 134, connecting the first wiring 118 to one of the source and drain of the transistor, and connecting the patch electrode 108 to the other of the source and drain, a control signal can be applied to a predetermined patch electrode selected from the plurality of patch electrodes 108 arranged in a matrix. By providing the switching element 134 to each patch electrode 108 in the radio wave reflecting surface 120, a control voltage can be applied to each patch electrode 108 arranged in a horizontal row along the first direction (X-axis direction) or each patch electrode 108 arranged in a vertical row along the second direction (Y-axis direction). For example, when the radio wave reflecting surface 120 is upright, the reflection direction of the reflected wave can be controlled in the left-right and up-down directions.

[0059] As described above, the radio wave reflecting device 10 includes a radio wave reflector having a radio wave reflecting surface 120 on which a plurality of reflecting elements, each having a patch electrode and a common electrode, are arranged, and a housing that houses the radio wave reflector, and the housing has a heat insulating structure, and at least the area that covers the radio wave reflecting surface 120 of the radio wave reflector is formed of a dielectric material, thereby suppressing heat transfer from the outside air temperature to the radio wave reflector. By suppressing heat transfer from the outside air temperature, the temperature inside the housing 200 can be kept within an appropriate temperature range for the liquid crystal, and power consumption of devices such as heaters and coolers that adjust the temperature inside the housing 200 to an appropriate temperature range for the liquid crystal can be suppressed.

[0060] Second Embodiment A radio wave reflecting device 10 according to one embodiment of the present invention will be described with reference to Fig. 11. Fig. 11 is an end view showing a radio wave reflecting device 10 according to one embodiment of the present invention. Note that descriptions of configurations that are the same as or similar to those in Fig. 1 may be omitted.

[0061] The radio wave reflecting device 10 may have a configuration that allows power supply and information input / output via wireless communication. As shown in FIG. 11 , the radio wave reflecting device 10 may have a power receiving unit 230 that can receive power from an externally installed wireless power supply unit 1100 within the storage space 208. The power receiving unit 230 may receive information from an externally installed wireless control unit 1102. The power receiving unit 230 may be electrically connected to the radio wave reflector 100. As shown in FIG. 11 , the power receiving unit 230 may be disposed within the protective unit 204. The power receiving unit 230 may also be disposed on the surface opposite the radio wave reflecting surface 120. The power receiving unit 230 may use a known power receiving method, and may have, for example, a power receiving coil.

[0062] The radio wave reflecting device 10 may have fixing portions 232 that fix the inner shell 214 to the outer shell 212. The fixing portions 232 are disposed in through holes 234 that penetrate the inner shell 214 and the outer shell 212. There are no particular limitations on the shape or structure of the through holes 234, but a structure that sufficiently maintains airtightness between the inner shell 214 and the outer shell 212 is preferred. The inner shell 214 may be fixed to the outer shell 212 by a plurality of fixing portions 232. As shown in FIG. 11 , fixing portion 232-1 may be disposed in through hole 234-1 provided in the upper part of the housing 200, and fixing portion 232-2 may be disposed in through hole 234-2 provided in the lower part of the housing 200. When the radio wave reflecting device 10 is provided with the radiation plate 202, the radiation plate 202 may have a through-hole 234-3 that overlaps with the through-hole 234-1 provided in the housing 200, and the fixed portion 232-1 may be disposed in the through-hole 234-3. As shown in Fig. 11, the radiation plate 202 may have a through-hole 234-4 that overlaps with the through-hole 234-2 in the housing 200, and the fixed portion 232-2 may be disposed in the through-hole 234-2 in the housing 200 and the through-hole 234-4 in the radiation plate 202. The fixed portion 232 may be made of iron, stainless steel, copper, or the like.

[0063] Third Embodiment A radio wave reflecting device 10 according to one embodiment of the present invention will be described with reference to Fig. 12. Fig. 12 is an end view showing a radio wave reflecting device 10 according to one embodiment of the present invention. Note that descriptions of configurations that are the same as or similar to those in Fig. 1 may be omitted.

[0064] The housing 200 may have a lid 236 and a bottom 238. The lid 236 may be arranged to cover the radio wave reflecting surface 120 of the radio wave reflector 100. The bottom 238 may be arranged facing the opposite side of the radio wave reflecting surface 120. The lid 236 and the bottom 238 may be joined to seal the interior of the housing 200. When the lid 236 and the bottom 238 are joined, a sealing portion 240 may be provided between the lid 236 and the bottom 238, as shown in FIG. 12. The sealing portion 240 may also be arranged along the outer edge of the housing 200 shown in FIG. 6 or 8. The sealing portion 240 may be arranged to surround the radio wave reflector 100 and the protective portion 204. The sealing portion 240 may be made of rubber materials such as fluororubber and nitrile rubber, resin, plastic, or an adhesive agent for these materials. Alternatively, the lid 236 and the bottom 238 may be directly joined by heating or the like.

[0065] In the housing 200, the lid portion 236 that covers the radio wave reflecting surface 120 is joined to the lid portion 236, and the lid portion 236 has a bottom portion 238 that is arranged facing the side opposite the radio wave reflecting surface 120, so that the radio wave reflecting device 10 can incorporate the radio wave reflecting plate 100 into the housing 200 without providing an insertion port 225 for inserting the radio wave reflecting plate 100.

[0066] The bottom 238 may have an opening 218-2. As shown in FIG. 12 , the outer shell 212 of the bottom 238 may have an opening 218-2. The opening 218-2 may penetrate the outer shell 212. The opening 218-2 may function as an exhaust port for evacuating the space 216. The outer shell 212 is provided with a sealing portion 220-2 that seals the opening 218-2 to keep the space 216 hermetically sealed.

[0067] The above-described embodiments of the present invention can be combined as appropriate as long as they are not mutually inconsistent. A product in which a person skilled in the art appropriately adds or deletes components or modifies designs, or adds or omits steps or modifies conditions, based on each embodiment, is also included within the scope of the present invention as long as it includes the gist of the present invention.

[0068] Furthermore, even if there are other effects and advantages different from those brought about by the aspects of each of the above-mentioned embodiments, if they are clear from the description in this specification or can be easily predicted by a person skilled in the art, they are naturally understood to be brought about by the present invention.

[0069] 10: radio wave reflecting device, 100: radio wave reflecting plate, 100a: radio wave reflecting plate, 100b: radio wave reflecting plate, 100W: width, 102: reflecting element, 102a: reflecting element, 102b: reflecting element, 102m: arrangement, 104: dielectric substrate, 106: opposing substrate, 108: patch electrode, 110: common electrode, 112a: first alignment film, 112b: second alignment film, 114: liquid crystal layer, 116: liquid crystal molecules, 118: first wiring, 120: radio wave reflecting surface, 122: surrounding area region, 124: first drive circuit, 126: terminal portion, 128: sealing material, 130: second drive circuit, 132: second wiring, 134: switching element, 136: undercoat layer, 138: first gate electrode, 140: first gate insulating layer, 142: semiconductor layer, 144: first connection wiring, 146: second gate insulating layer, 148: second gate electrode, 150: first interlayer insulating layer, 152: second connection wiring, 154: second interlayer insulating layer, 156: planarization layer, 158: passivation layer, 200: housing, 200-1: first surface, 200-2: second surface, 200W: width, 202: radiation plate, 204: protection part, 206: fixing part, 208: storage space, 210: heat insulating layer, 212: outer shell, 212-1: first surface, 212-2: second surface, 214: inner shell, 214-1: first surface, 214-2: second surface, 216: space, 218-1: opening, 218-2: opening, 220: sealing part, 220-1: sealing part, 22 0-2: sealing portion, 222: opening, 224: opening, 225: input port, 225W: width, 226: through hole, 228: cable, 230: power receiving portion, 232: fixing portion, 232-1: fixing portion, 232-2: fixing portion, 234: through hole, 234-1: through hole, 234-2: through hole, 234-3: through hole, 234-4: through hole, 236: lid portion, 238: bottom portion, 240: sealing portion, 1000: pillar, 1100: wireless power supply portion, 1102: wireless control portion

Claims

1. A radio wave reflecting device comprising: a radio wave reflector having a radio wave reflecting surface on which a plurality of reflecting elements, each having a patch electrode and a common electrode, are arranged; and a housing that houses the radio wave reflector, wherein the housing has a heat-insulating structure and at least the area that covers the radio wave reflecting surface of the radio wave reflector is made of a dielectric material.

2. The radio wave reflecting device according to claim 1, wherein the heat insulating structure is a vacuum heat insulating structure.

3. The radio wave reflecting device according to claim 1, wherein the housing has an inner shell and an outer shell located outside the inner shell, and a heat insulating layer in a vacuum state is provided between the inner shell and the outer shell.

4. The radio wave reflecting device according to claim 1, wherein the housing has an inner shell and an outer shell located outside the inner shell, and has a heat insulating layer filled with heat insulating material between the inner shell and the outer shell.

5. The radio wave reflecting device according to claim 3, wherein the inner shell is joined to the outer shell.

6. A radio wave reflecting device as described in claim 3 or claim 4, wherein the outer shell has a first surface covering the radio wave reflecting surface and a second surface opposite the first surface, and further has a radiation plate facing the second surface.

7. The radio wave reflecting device according to claim 6, wherein the radiation plate is made of metal or thermally conductive resin.

8. The radio wave reflecting device according to claim 1, further comprising a power receiving section electrically connected to said radio wave reflecting plate and having a power receiving coil.

9. The radio wave reflecting device according to claim 8, wherein the power receiving unit is located in a storage space surrounded by the housing.

10. The radio wave reflecting device according to claim 1, wherein the radio wave reflecting plate has a plurality of wirings and a terminal portion electrically connected to the plurality of wirings, and further has a protective portion covering the terminal portion.

11. The radio wave reflecting device according to claim 10, further comprising a cable electrically connected to the terminal portion and covered by the protective portion, the cable extending to the outside of the housing via the protective portion that penetrates the housing.

12. The radio wave reflecting device according to claim 1, wherein the housing has a lid that covers the radio wave reflecting surface, and a bottom that is joined to the lid and is positioned facing the surface opposite the radio wave reflecting surface.

Images