Radio wave reflection plate and radio wave reflection device

Abstract

This radio wave reflection plate includes: a patch electrode on a first substrate; a ground electrode on a second substrate different from the first substrate; a liquid crystal layer between the patch electrode and the ground electrode; a reflection antenna region in which the patch electrode and the ground electrode overlap in a plan view; and a peripheral region that surrounds the reflection antenna region in a plan view and in which only the ground electrode is provided. Each of the patch electrode and the ground electrode includes a plurality of openings.

Description

Radio wave reflectors and radio wave reflectors

[0001] An embodiment of the present invention relates to a radio wave reflector that can control the reflection direction of incident radio waves, and also to a radio wave reflecting device that combines a plurality of radio wave reflectors.

[0002] A phased array antenna device (hereinafter sometimes referred to as a "radio wave reflector") controls the directivity of a fixed antenna by adjusting the amplitude and phase of a high-frequency signal applied to each of a plurality of antenna elements arranged in a plane. The phased array antenna device requires a phase shifter. A phased array antenna device using a phase shifter that utilizes a change in the dielectric constant due to the orientation state of liquid crystals has been disclosed (see, for example, Patent Document 1).

[0003] The antenna elements of the phased array antenna device in Patent Document 1 include multiple strip lines, a planar electrode facing the multiple strip lines, and a liquid crystal layer disposed between the multiple strip lines and the planar electrode. Different voltages are applied to the multiple strip lines in the multiple antenna elements. The dielectric constant of the liquid crystal layer for each antenna element is then adjusted to superimpose the reflected waves, thereby changing the phase. This allows the reflection direction of the radio wave to be set to any desired direction.

[0004] Japanese Patent Application Publication No. 11-103201

[0005] Radio wave reflectors can simplify radio wave base stations. However, because the installation of radio wave reflectors can spoil the scenery, there is a demand for transparent radio wave reflectors for the fifth generation mobile communication system (G5). Radio wave reflectors using liquid crystal can be made transparent. Furthermore, by combining and arranging multiple transparent radio wave reflectors, it is possible to create a large-area transparent radio wave reflecting device. However, transparent radio wave reflecting devices have the problem of poor visibility at the boundaries between radio wave reflectors, such as the seam between two adjacent radio wave reflectors being noticeable.

[0006] In view of the above problems, one object of one embodiment of the present invention is to provide a transparent radio wave reflector that improves visibility at the boundaries between radio wave reflectors when multiple radio wave reflectors are combined and arranged. Another object of one embodiment of the present invention is to provide a radio wave reflecting device in which multiple transparent radio wave reflectors are combined and arranged, improving visibility at the boundaries between the radio wave reflectors.

[0007] A radio wave reflector according to one embodiment of the present invention includes a patch electrode on a first substrate, a ground electrode on a second substrate different from the first substrate, a liquid crystal layer between the patch electrode and the ground electrode, a reflective antenna region in which the patch electrode and the ground electrode overlap in a planar view, and a peripheral region in which only the ground electrode is provided, surrounding the reflective antenna region in a planar view, and wherein each of the patch electrode and the ground electrode includes a plurality of openings.

[0008] The antenna includes a first radio wave reflector and a second radio wave reflector adjacent to the first radio wave reflector, and each of the first radio wave reflector and the second radio wave reflector includes a patch electrode on a first substrate, a ground electrode on a second substrate different from the first substrate, a liquid crystal layer between the patch electrode and the ground electrode, a reflective antenna region in which the patch electrode and the ground electrode overlap in a planar view, and a peripheral region in which only the ground electrode is provided, surrounding the reflective antenna region in a planar view, and each of the patch electrode and the ground electrode includes a plurality of openings, and the peripheral region of the first radio wave reflector is in contact with the peripheral region of the second radio wave reflector.

[0009] 1 is a schematic plan view showing an outline of the configuration of a radio wave reflecting device according to one embodiment of the present invention; FIG. 2 is a schematic plan view showing an outline of the configuration of a radio wave reflector according to one embodiment of the present invention; FIG. 3 is a schematic cross-sectional view showing the configuration of a reflecting antenna cell of a radio wave reflector according to one embodiment of the present invention and the direction in which radio waves are reflected by the reflecting antenna cell; FIG. 4 is a schematic plan view showing the configuration of a reflecting antenna region and a peripheral region of a radio wave reflector according to one embodiment of the present invention; FIG. 5 is a schematic plan view showing the configuration of a reflecting antenna region and a peripheral region of a radio wave reflector according to one embodiment of the present invention; FIG. 6 is a schematic plan view showing the configuration of a reflecting antenna region and a peripheral region of a radio wave reflector according to one embodiment of the present invention; FIG. 7 is a schematic cross-sectional view showing the configuration of a reflecting antenna region of a radio wave reflector according to one embodiment of the present invention;

[0010] 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 schematic representations of the width, thickness, shape, etc. of each part 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 drawings, components similar to those described above with reference to the previous figures may be designated by the same reference numerals, and detailed descriptions may be omitted as appropriate. Furthermore, the letters "first" and "second" attached to components are convenient labels used to distinguish between components and have no further meaning unless otherwise specified.

[0011] In this specification, when a member or region is referred to as being "on (or under)" another member or region, unless otherwise specified, this includes not only the case where it is directly above (or directly under) the other member or region, but also the case where it is above (or under) the other member or region, i.e., the case where another component is included between the member or region and above (or under) the other member or region.

[0012] In this specification, two components being "substantially identical" means that the two components have different sizes but the same shape, that the difference in area between the two components is within ±5%, or that the difference in aperture ratio between the two components is within 5%.

[0013] A radio wave reflecting device 1 or a radio wave reflecting plate 10 according to one embodiment of the present invention will be described with reference to FIGS. 1A to 3. FIG.

[0014] 1. Configuration of Radio Wave Reflecting Device 1 FIG. 1A is a schematic plan view showing an outline of the configuration of a radio wave reflecting device 1 according to one embodiment of the present invention.

[0015] As shown in FIG. 1A , the radio wave reflecting device 1 includes a plurality of radio wave reflecting plates 10. The two radio wave reflecting plates 10 are arranged so that their end faces are in contact with each other. Therefore, each radio wave reflecting plate 10 includes at least one end face that is in contact with an end face of another radio wave reflecting plate 10. While the number of radio wave reflecting plates 10 shown in FIG. 1A is four, the number of radio wave reflecting plates 10 in the radio wave reflecting device 1 is not limited to this. The number of radio wave reflecting plates 10 in the radio wave reflecting device 1 may be two or more. Furthermore, while the planar shape of the radio wave reflecting plate 10 shown in FIG. 1A is rectangular, the planar shape of the radio wave reflecting plate 10 in the radio wave reflecting device 1 is not limited to this. The planar shape of the radio wave reflecting plate 10 in the radio wave reflecting device 1 may be, for example, hexagonal. It is preferable that the radio wave reflecting plates 10 have a planar shape that does not create gaps between the radio wave reflecting plates 10 when multiple radio wave reflecting plates 10 are combined and arranged.

[0016] 2. Configuration of Radio Wave Reflector 10 FIG. 1B is a schematic plan view showing an outline of the configuration of a radio wave reflector 10 according to one embodiment of the present invention.

[0017] As shown in FIG. 1B , the radio wave reflector 10 includes a reflecting antenna region 11 and a peripheral region 12. The reflecting antenna region 11 is provided in the center of the radio wave reflector 10, and the peripheral region 12 surrounds the reflecting antenna region 11 and is provided in the peripheral region of the radio wave reflector 10. A plurality of reflecting antenna cells 100 are provided in the reflecting antenna region 11. The plurality of reflecting antenna cells 100 are arranged in a matrix in the x-axis direction and the y-axis direction. However, the arrangement of the plurality of reflecting antenna cells 100 is not limited to this. A driving circuit 200 that generates a control signal to control each of the plurality of reflecting antenna cells 100 is provided in the peripheral region. Wiring is also provided to electrically connect the reflecting antenna cells 100 and the driving circuit 200. Although not shown, the peripheral region 12 may be provided with a terminal for supplying signals or power from an external source.

[0018] Now, the configuration and function of the reflecting antenna cell 100 will be described with reference to FIG.

[0019] Fig. 2 is a schematic cross-sectional view showing the configuration of a reflecting antenna cell 100 of a radio wave reflector 10 according to one embodiment of the present invention and the direction in which radio waves are reflected by the reflecting antenna cell 100. Fig. 2 shows two adjacent reflecting antenna cells 100, namely, a first reflecting antenna cell 100-1 and a second reflecting antenna cell 100-2.

[0020] Each of the first reflecting antenna cell 100-1 and the second reflecting antenna cell 100-2 includes a patch electrode 120 provided on the first substrate 110-1 and a ground electrode 130 provided on the second substrate 110-2. The patch electrode 120 of the first reflecting antenna cell 100-1 and the patch electrode 120 of the second reflecting antenna cell 100-2 are not electrically connected. On the other hand, the ground electrode 130 is provided in common to the first reflecting antenna cell 100-1 and the second reflecting antenna cell 100-2. A first alignment film 140-1 is provided on the patch electrode 120. A second alignment film 140-2 is provided on the ground electrode 130. The first substrate 110-1 and the second substrate 110-2 are arranged so that the patch electrode 120 and the ground electrode 130 face each other, and a liquid crystal layer 150 is provided between the first alignment film 140-1 and the second alignment film 140-2.

[0021] Each of the first substrate 110-1 and the second substrate 110-2 can be made of glass, quartz, resin, or the like.

[0022] A metal material can be used for each of the patch electrode 120 and the ground electrode 130. For example, the metal material is molybdenum (Mo), tungsten (W), titanium (Ti), aluminum (Al), copper (Cu), or an alloy thereof. Each of the patch electrode 120 and the ground electrode 130 may have a single-layer structure or a multilayer structure.

[0023] Each of the first alignment film 140-1 and the second alignment film 140-2 can be made of a polyimide resin, etc. The first alignment film 140-1 and the second alignment film 140-2 have been subjected to alignment treatment using a rubbing method, a photo-alignment method, or the like.

[0024] The liquid crystal layer 150 includes a liquid crystal material having dielectric anisotropy. For example, a nematic liquid crystal or a cholesteric liquid crystal containing liquid crystal molecules capable of twist alignment can be used as the liquid crystal material of the liquid crystal layer 150. Furthermore, the liquid crystal layer 150 preferably includes a chiral agent to stabilize the twist alignment of the liquid crystal molecules.

[0025] The initial alignment state (alignment state when no voltage is applied) of the liquid crystal molecules in the liquid crystal layer 150 is controlled by the first alignment film 140-1 and the second alignment film 140-2 that have been subjected to alignment treatment. When a voltage is applied to the patch electrode 120 and a potential difference is formed between the patch electrode 120 and the ground electrode 130, the alignment state of the liquid crystal molecules in the liquid crystal layer 150 changes, and the dielectric constant of the liquid crystal layer 150 also changes. As will be described in detail later, the radio wave reflector 10 uses the change in the dielectric constant of the liquid crystal layer 150 to control the phase of the reflected radio waves.

[0026] When liquid crystal molecules have positive dielectric anisotropy, the dielectric constant of the liquid crystal becomes larger when a voltage is applied than when no voltage is applied. Furthermore, when liquid crystal molecules have negative dielectric anisotropy, the dielectric constant of the liquid crystal becomes smaller when a voltage is applied than when no voltage is applied. The liquid crystal layer 150 formed of liquid crystals with dielectric anisotropy can also be considered a variable dielectric layer. By utilizing the dielectric anisotropy of the liquid crystal layer 150, the reflecting antenna cell 100 can control the phase delay (or non-delay) of radio waves scattered by the ground electrode 130.

[0027] As described above, the first reflecting antenna cell 100-1 and the second reflecting antenna cell 100-2 have the same basic configuration. That is, each of the plurality of reflecting antenna cells 100 has the above-described basic configuration. Meanwhile, each of the plurality of reflecting antenna cells 100 is electrically connected to a switching element 160. Specifically, the switching element 160 is electrically connected to the patch electrode 120, and by controlling the switching element 160, the voltage applied to the patch electrode 120 changes.

[0028] As shown in Figure 2, radio waves are incident on the radio wave reflector 10 in a direction parallel to the normal to the surface of the first substrate 110-1 (see "Propagation direction of incident wave" in Figure 2). Here, consider a case where a first voltage V1 is applied to the patch electrode 120 of the first reflecting antenna cell 100-1, and a second voltage V2 different from the first voltage V1 is applied to the patch electrode 120 of the second reflecting antenna cell 100-2. When radio waves having the same phase are incident on the first reflecting antenna cell 100-1 and the second reflecting antenna cell 100-2, scattered waves with different phases are generated in the first reflecting antenna cell 100-1 and the second reflecting antenna cell 100-2 because the dielectric constants of the liquid crystal layers 150 are different between the first reflecting antenna cell 100-1 and the second reflecting antenna cell 100-2. For example, as shown in Figure 2, the phase of the scattered wave R2 scattered by the second reflecting antenna cell 100-2 leads the phase of the scattered wave R1 scattered by the first reflecting antenna cell 100-1. In this case, the radio wave reflected by the reflecting antenna area 11 travels in a direction different from the normal direction to the surface of the first substrate 110-1 (see "Direction of travel of reflected wave" in Figure 2). Although Figure 2 shows two adjacent reflecting antenna cells 100, the radio wave reflector 10 can separately control multiple reflecting antenna cells 100 arranged in a matrix. Therefore, the radio wave reflector 10 can control the reflection direction of the radio wave in any direction.

[0029] The frequency bands to which the radio wave reflector 10 is applicable 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. As described above, in the liquid crystal layer 150, the orientation state of the liquid crystal molecules changes depending on the voltage applied to the patch electrode 120, but does not substantially follow the frequency of the radio wave incident on the ground electrode 130. Due to such characteristics of the liquid crystal molecules, the dielectric constant of the liquid crystal layer 150 can be changed by the patch electrode 120, and the ground electrode 130 can scatter the radio waves and control the phase of the scattered radio waves.

[0030] 3 is a schematic plan view showing the configuration of the reflecting antenna region 11 and the peripheral region 12 of the radio wave reflector 10 according to one embodiment of the present invention. Specifically, Fig. 3 is a partial enlarged view of region A in Fig. 1B , which includes four reflecting antenna cells 100, and region A includes part of the reflecting antenna region 11 and part of the peripheral region 12.

[0031] In the reflecting antenna area 11, the radio wave reflector 10 includes a first area 101 and a second area 102. The first area 101 is an area where the patch electrode 120 and the ground electrode 130 overlap in a planar view. That is, the first area 101 is an area corresponding to the reflecting antenna cell 100. The second area 102 is an area where the patch electrode 120 and the ground electrode 130 do not overlap in a planar view. That is, the second area 102 is an area where only the ground electrode 130 is provided.

[0032] In the first region 101, the patch electrode 120 includes a plurality of first openings 121. Furthermore, in the first region 101, the ground electrode 130 includes a plurality of second openings 131. The cross-sectional shape of each of the first openings 121 and the second openings 131 is rectangular, but is not limited to this. The planar shape of the plurality of second openings 131 is substantially the same as the planar shape of the plurality of first openings 121. The second openings 131 have substantially the same opening area as the first openings 121 and overlap with the first openings 121. Therefore, in the first region 101, light can pass through the first openings 121 and the second openings 131.

[0033] In the second region 102, the ground electrode 130 includes a plurality of third openings 132. The cross-sectional shape of the third openings 132 is rectangular, but is not limited to this. The planar shape of the plurality of third openings 132 is substantially the same as the planar shape of the plurality of second openings 131. In other words, the third openings 132 have substantially the same opening area as the second openings 131. Since the patch electrode 120 is not provided in the second region 102, light can pass through the third openings 132 in the second region 102.

[0034] The peripheral region 12 has a similar configuration to the second region 102. That is, in the peripheral region 12, the ground electrode 130 includes a plurality of third openings 132. The ground electrode 130 in the second peripheral region 12 has substantially the same planar shape as the ground electrode 130 in the reflecting antenna region 11. Specifically, the ground electrode 130 in the peripheral region 12 has a lattice shape. Since no patch electrode is provided in the peripheral region 12, light can pass through the third openings 132 in the peripheral region 12.

[0035] The patch electrode 120 and the ground electrode 130 do not transmit light. However, in the radio wave reflector 10, many openings (plurality of first openings 121, pluralities of second openings 131, and pluralities of third openings 132) are provided in the patch electrode 120 and the ground electrode 130 to allow light to pass through, and light incident on the radio wave reflector 10 passes through the openings. Therefore, the radio wave reflector 10 is a transparent radio wave reflector.

[0036] The radio wave reflecting device 1 is arranged by combining a plurality of radio wave reflecting plates 10, and the peripheral region 12 of the radio wave reflecting plate 10 is provided with a ground electrode 130 having substantially the same pattern shape as the ground electrode 130 provided in the reflecting antenna region 11. Therefore, even when two radio wave reflecting plates 10 are adjacent to each other, the boundary between the two adjacent peripheral regions 12 is less noticeable. In other words, in the radio wave reflecting device 1 having transparency, the visibility of the boundary between the radio wave reflecting plates 10 can be improved.

[0037] 4A and 4B , a radio wave reflector 10A will be described as a modification of the radio wave reflector 10. The radio wave reflecting device 1 can also be configured to combine and arrange a plurality of radio wave reflectors 10A. In the following, when the radio wave reflector 10A includes the same components as the radio wave reflector 10, the description of those components may be omitted.

[0038] 4A and 4B are schematic plan views showing the configuration of the reflecting antenna region 11 and the peripheral region 12A of the radio wave reflector 10A according to one embodiment of the present invention. Specifically, each of Fig. 4A and 4B is a partial enlarged view of the region A including the four reflecting antenna cells 100 in Fig. 1B.

[0039] As shown in FIG. 4A , the peripheral region 12A includes a ground electrode 133 and a plurality of fourth openings 134. Specifically, the peripheral region 12A includes the ground electrode 133 formed in the same layer as the ground electrode 130. The ground electrode 133 includes a plurality of fourth openings 134 extending in the y-axis direction (i.e., the direction along the end surface of the radio wave reflector 10A). In other words, the peripheral region 12A includes the ground electrode 133 having a linear shape different from the lattice-shaped ground electrode 130. The first width w1 of the linear shape of the ground electrode 133 may be equal to, smaller than, or larger than the second width w2 of the fourth openings 134. The first width w1 and the second width w2 may be determined taking into account the aperture ratio of the ground electrode 130 in the reflecting antenna region 11 (hereinafter, sometimes simply referred to as the “aperture ratio of the reflecting antenna region 11”). The aperture ratio of the reflecting antenna region 11 is expressed by the aperture area of ​​the ground electrode 130 relative to the area of ​​the reflecting antenna region 11. In other words, the aperture ratio of the reflecting antenna region 11 is represented by the total area of ​​the second opening 131 and the third opening 132 relative to the area of ​​the reflecting antenna region 11. On the other hand, the aperture ratio of the peripheral region 12 is represented by the aperture area of ​​the ground electrode 133 relative to the area of ​​the peripheral region 12. In other words, the aperture ratio of the peripheral region 12 is represented by the area of ​​the fourth opening 134 relative to the area of ​​the peripheral region 12. Therefore, for example, the first width w1 and the second width w2 may be determined so that the aperture ratio of the peripheral region 12 is approximately the same as the aperture ratio of the reflecting antenna region 11.

[0040] The ground electrode 133 in the peripheral region 12A is a dummy pattern, unlike the ground electrode 130 in the reflecting antenna region 11. Therefore, the ground electrode 133 does not need to be grounded and may be in a floating state.

[0041] Although the first width w1 and the second width w2 shown in Fig. 4A are provided at equal intervals, the second width w2 of the fourth opening 134 may vary. For example, as shown in Fig. 4B, the fourth opening 134 may be provided so that the second width w2 gradually decreases in the direction from the reflective antenna area 11 toward the end face of the radio wave reflector 10A. In this case, the ground electrodes 133 are densely arranged near the boundary between the two radio wave reflectors 10A, making the boundary between the two radio wave reflectors 10A even less noticeable.

[0042] In this modification, the ground electrode 133 provided in the peripheral region 12A has been described as having a linear shape, but the planar shape of the ground electrode 133 provided in the peripheral region 12A is not limited to this. Regardless of the shape of the ground electrode 133, the aperture ratio of the peripheral region 12A can be made to approximately match the aperture ratio of the reflecting antenna region by adjusting the size (area, width, etc.) of the ground electrode 133.

[0043] In this modified example, the radio wave reflecting device 1 is also arranged by combining multiple radio wave reflecting plates 10A, but a ground electrode 133 having a different planar shape from the ground electrode 130 is provided in the peripheral region 12A of the radio wave reflecting plate 10A so that the aperture ratio of the peripheral region 12A is approximately the same as the aperture ratio of the reflecting antenna region 11. Therefore, even when two radio wave reflecting plates 10A are adjacent to each other, the boundary between the two adjacent peripheral regions 12A is less noticeable. In other words, in the transparent radio wave reflecting device 1, the visibility of the boundary between the radio wave reflecting plates 10A can be improved.

[0044] <Second Modification of First Embodiment> On the first substrate 110-1, not only the patch electrode 120 but also a switching element for controlling the potential supplied to the patch electrode 120 is provided. Here, the configuration of the reflection antenna region 11 of the radio wave reflector 10 will be described in detail with reference to Figs. 5 and 6 .

[0045] Fig. 5 is a schematic plan view showing the configuration of the reflecting antenna region 11 of the radio wave reflector 10 according to one embodiment of the present invention. Fig. 6 is a schematic cross-sectional view showing the configuration of the reflecting antenna region 11 of the radio wave reflector 10 according to one embodiment of the present invention. Specifically, Fig. 6 is a cross-sectional view of the reflecting antenna region 11 taken along line B1-B2 in Fig. 5. As described above, the first region 101 corresponds to the reflecting antenna cell 100.

[0046] 5 and 6 show a transistor as an example of the switching element 160. That is, the switching element 160 includes a semiconductor layer 161, a gate insulating layer 162, and a gate electrode 163. The semiconductor layer 161 is provided on the first substrate 110-1. The gate insulating layer 162 is provided on the first substrate 110-1 so as to cover the semiconductor layer 161. The gate electrode 163 is provided on the gate insulating layer 162 so as to overlap the semiconductor layer 161. The gate electrode 163 is electrically connected to a selection signal line 166. An interlayer insulating layer 164 is provided on the gate electrode 163. Two openings are formed in the interlayer insulating layer 164, through which the semiconductor layer 161 is exposed. The semiconductor layer 161 is electrically connected to the patch electrode 120 through one opening and to the data signal line 167 through the other opening. A planarization layer 165 is provided on the interlayer insulating layer 164 and the data signal line 167. The patch electrode 120 is provided on the planarization layer 165 .

[0047] The semiconductor layer 161 is formed using a silicon semiconductor such as amorphous silicon or polycrystalline silicon, or an oxide semiconductor such as indium gallium zinc oxide, indium gallium aluminum oxide, indium gallium oxide, zinc oxide, or gallium oxide. The gate insulating layer 162 and the interlayer insulating layer 164 are formed using, for example, a silicon oxide film or a stacked structure of a silicon oxide film and a silicon nitride film. The gate electrode 163 and the selection signal line 166 may be formed in the same layer. The gate electrode 163 and the selection signal line 166 are formed using, for example, molybdenum (Mo), tungsten (W), or an alloy thereof. The data signal line 167 is formed using a metal material such as titanium (Ti), aluminum (Al), or molybdenum (Mo). For example, the data signal line 167 is formed using a stacked structure of titanium (Ti), aluminum (Al), and titanium (Ti), or a stacked structure of molybdenum (Mo), aluminum (Al), and molybdenum (Mo). The planarizing layer 165 is formed using a resin material such as acrylic or polyimide.

[0048] The selection signal line 166 and the data signal line 167 are electrically connected to the drive circuit 200. A control signal from the drive circuit 200 is input to the switching element 160 via the selection signal line 166 and the data signal line 167. The switching element 160 operates based on the control signal, thereby changing the alignment state of the liquid crystal molecules in the liquid crystal layer 150.

[0049] As described above, not only the patch electrode 120 but also the switching element 160 is provided on the first substrate 110-1. The metal material contained in the switching element 160 is opaque to light. Therefore, in this modification, the aperture ratio of the reflective antenna region 11 is determined taking into consideration not only the light blocking by the ground electrode 130 but also the light blocking by the switching element 160, the selection signal line 166, and the data signal line 167. That is, in this modification, the aperture ratio of the reflective antenna region 11 is expressed as the total aperture area relative to the area of ​​the reflective antenna region 11. Here, the total aperture area is the area of ​​the region where none of the patch electrode 120, the ground electrode 130, the switching element 160, the selection signal line 166, and the data signal line 167 is provided in a plan view. In this modification, for example, the area of ​​the third opening 132 in the peripheral region 12 may be adjusted so that the aperture ratio of the peripheral region 12 is approximately the same as the aperture ratio of the reflective antenna region 11.

[0050] In this modification, the radio wave reflecting device 1 is also arranged by combining a plurality of radio wave reflecting plates 10B, but the aperture ratio of the peripheral region 12 of the radio wave reflecting plate 10 is substantially the same as the aperture ratio of the reflecting antenna region 11. Therefore, even when two radio wave reflecting plates 10A are adjacent to each other, the boundary between the two adjacent peripheral regions 12 is less noticeable. In other words, in the radio wave reflecting device 1 having transparency, the visibility of the boundary between the radio wave reflecting plates 10 can be improved.

[0051] 7 and 8, a radio wave reflecting device 1 and a radio wave reflecting plate 10B according to one embodiment of the present invention will be described. The radio wave reflecting device 1 is configured by combining and arranging a plurality of radio wave reflecting plates 10B. In the following, when the radio wave reflecting plate 10B includes the same components as the radio wave reflecting plate 10, the description of those components may be omitted.

[0052] Fig. 7 is a schematic plan view showing the configuration of the peripheral region 12B of a radio wave reflector 10B according to one embodiment of the present invention. Fig. 8 is a schematic cross-sectional view showing the configuration of the peripheral region 12B of a radio wave reflector 10B according to one embodiment of the present invention. Specifically, Fig. 8 is a cross-sectional view of the peripheral region 12B taken along line C1-C2 in Fig. 7. Note that, for convenience, components on the first substrate 110-1 side, the liquid crystal layer 150, and the like are omitted from Fig. 8.

[0053] 7 and 8 , the peripheral region 12B of the radio wave reflector 10B includes a ground electrode 130, a third opening 132, a plurality of dummy pattern electrodes 135, and an insulating layer 136. The insulating layer 136 covers the ground electrode 130 and is provided on the ground electrode 130. The plurality of dummy pattern electrodes 135 are provided on the insulating layer 136. In other words, the plurality of dummy pattern electrodes 135 are provided on a different layer from the ground electrode 130.

[0054] The dummy pattern electrode 135 can be made of the same metal material as the ground electrode 130. The dummy pattern electrode 135 does not need to be grounded, and may be in a floating state.

[0055] Although the planar shape of the dummy pattern electrode 135 shown in FIG. 7 is rectangular, the planar shape of the dummy pattern electrode 135 is not limited to this. The planar shape of the dummy pattern electrode 135 may also be circular. Furthermore, the size of the dummy pattern electrode 135 is not particularly limited. For example, the area of ​​the dummy pattern electrode 135 may be the same as, larger than, or smaller than the opening area of ​​the third opening 132. Furthermore, the position at which the dummy pattern electrode 135 is disposed is not particularly limited. The dummy pattern electrode 135 may be disposed so as to overlap the ground electrode 130, or may be disposed so as not to overlap the ground electrode 130.

[0056] In this embodiment, the aperture ratio of the peripheral region 12B can be adjusted by adjusting the shape, size, and position of the dummy pattern electrode 135. Furthermore, by providing the dummy pattern electrode 135 spaced apart from the ground electrode 130, a configuration similar to the patch electrode 120 spaced apart from the ground electrode 130 in the reflecting antenna region 11 can be formed in the peripheral region 12B. Therefore, the viewing angle dependency of the peripheral region 12B can be made closer to the viewing angle dependency of the reflecting antenna region 11. This makes the boundary between the two adjacent peripheral regions 12B less noticeable, even when two radio wave reflectors 10B are adjacent to each other. In other words, the visibility of the boundary between the radio wave reflectors 10B can be improved in the transparent radio wave reflecting device 1.

[0057] In the above description, the configuration in which the dummy pattern electrode 135 is provided on the second substrate 110-2 has been described, but in this embodiment, a configuration in which the dummy pattern electrode 135 is provided on the first substrate 110-1 can also be applied.

[0058] The embodiments and modifications of the present invention can be combined as appropriate as long as they are not mutually inconsistent. Furthermore, even if a person skilled in the art adds or deletes components or modifies the design as appropriate based on the embodiments, or adds or omits steps or modifies conditions, such additions or deletions or modifications are made to the embodiments, they will also be included in the scope of the present invention as long as they include the gist of the present invention.

[0059] Even if there are other effects and advantages different from those brought about by the above-described embodiments, those that are clear from the description in this specification or that can be easily predicted by a person skilled in the art are naturally understood to be brought about by the present invention.

[0060] 1: radio wave reflecting device, 10, 10A, 10B: radio wave reflecting plate, 11: reflecting antenna area, 12, 12A, 12B: peripheral area, 100: reflecting antenna cell, 100-1: first reflecting antenna cell, 100-2: second reflecting antenna cell, 101: first area, 102: second area, 110-1: first substrate, 110-2: second substrate, 120: patch electrode, 121: first opening, 130, 133: ground electrodes, 131: second opening, 132: third opening, 134: fourth opening, 135: dummy pattern electrode, 136: insulating layer, 140-1: first alignment film, 140-2: second alignment film, 150: liquid crystal layer 160: Switching element, 161: Semiconductor layer, 162: Gate insulating layer, 163: Gate electrode, 164: Interlayer insulating layer, 165: Planarization layer, 166: Selection signal line, 167: Data signal line, 200: Drive circuit

Claims

1. A radio wave reflector including a patch electrode on a first substrate, a ground electrode on a second substrate different from the first substrate, a liquid crystal layer between the patch electrode and the ground electrode, a reflection antenna region where the patch electrode and the ground electrode overlap in a plan view, and a peripheral region that surrounds the reflection antenna region in the plan view and where only the ground electrode is provided, wherein each of the patch electrode and the ground electrode includes a plurality of openings.

2. The radio wave reflector according to claim 1, wherein the plurality of openings of the ground electrode in the peripheral region have substantially the same planar shape as the plurality of openings of the ground electrode in the reflection antenna region.

3. The radio wave reflector according to claim 1, wherein the aperture ratio of the peripheral region is substantially the same as the aperture ratio of the reflection antenna region.

4. The radio wave reflector according to claim 1, wherein the ground electrode in the peripheral region has a lattice shape.

5. The radio wave reflector according to claim 1, wherein the ground electrode in the peripheral region has a linear shape.

6. The radio wave reflector according to claim 1, wherein a dummy pattern electrode is provided as a layer different from the ground electrode in the peripheral region.

7. A radio wave reflection device including a first radio wave reflector and a second radio wave reflector adjacent to the first radio wave reflector, wherein each of the first radio wave reflector and the second radio wave reflector includes a patch electrode on a first substrate, a ground electrode on a second substrate different from the first substrate, a liquid crystal layer between the patch electrode and the ground electrode, a reflection antenna region where the patch electrode and the ground electrode overlap in a plan view, and a peripheral region that surrounds the reflection antenna region in the plan view and where only the ground electrode is provided, each of the patch electrode and the ground electrode includes a plurality of openings, and the peripheral region of the first radio wave reflector is in contact with the peripheral region of the second radio wave reflector.

8. The radio wave reflection device according to claim 7, wherein in each of the first radio wave reflector and the second radio wave reflector, the plurality of openings of the ground electrode in the peripheral region have substantially the same planar shape as the plurality of openings of the ground electrode in the reflection antenna region.

9. The radio wave reflection device according to claim 7, wherein in each of the first radio wave reflector and the second radio wave reflector, the aperture ratio of the peripheral region is substantially the same as the aperture ratio of the reflection antenna region.

10. The radio wave reflection device according to claim 7, wherein in each of the first radio wave reflector and the second radio wave reflector, the ground electrode in the peripheral region has a lattice shape.

11. The radio wave reflection device according to claim 7, wherein in each of the first radio wave reflector and the second radio wave reflector, the ground electrode in the peripheral region has a linear shape.

12. The radio wave reflection device according to claim 7, wherein in the peripheral region of each of the first radio wave reflector and the second radio wave reflector, a dummy pattern electrode is provided as a layer different from the ground electrode.

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