Radio wave reflection device

Abstract

A radio wave reflection device according to the present invention comprises: a metasurface reflector having a radio wave reflection region in which a plurality of radio wave reflection elements are arranged, and a frame region surrounding the radio wave reflection region; and a cover member disposed on a radio wave incident surface side of the metasurface reflector. The frame region includes a first region in which a wiring pattern is formed, and a second region in which a terminal section for connection to an external circuit is provided. The cover member includes a first radio wave absorption pattern provided in a region overlapping the first region, and a second radio wave absorption pattern provided in a region overlapping the second region. The size of the second radio wave absorption pattern is larger than the size of the first radio wave absorption pattern.

Description

radio wave reflector

[0001] One embodiment of the present invention relates to a radio wave reflecting device.

[0002] Since liquid crystal molecules have dielectric anisotropy, the dielectric constant of the liquid crystal layer can be controlled by adjusting the electric field applied to the liquid crystal layer containing the liquid crystal molecules to control the orientation of the liquid crystal molecules. It is known that by utilizing this property, it is possible to provide a radio wave reflection device whose reflection characteristics can be controlled (see, for example, Patent Documents 1 and 2).

[0003] JP 11-103201 A JP 2019-530387 A

[0004] An object of one embodiment of the present invention is to provide a novel radio wave reflecting device that includes a liquid crystal layer. Alternatively, an object of one embodiment of the present invention is to provide a radio wave reflecting device that includes a liquid crystal layer and has excellent radio wave reflection characteristics.

[0005] A radio wave reflection device according to one embodiment of the present invention comprises a metasurface reflector having a radio wave reflection area in which a plurality of radio wave reflection elements are arranged and a frame area surrounding the radio wave reflection area, and a cover member arranged on the radio wave incident surface side of the metasurface reflector, wherein the frame area includes a first area in which a wiring pattern is formed and a second area in which a terminal portion for connecting to an external circuit is provided, and the cover member includes a first radio wave absorbing pattern provided in an area overlapping with the first area and a second radio wave absorbing pattern provided in an area overlapping with the second area, and the size of the second radio wave absorbing pattern is larger than the size of the first radio wave absorbing pattern.

[0006] A radio wave reflection device according to one embodiment of the present invention comprises a metasurface reflector having a radio wave reflection area in which a plurality of radio wave reflection elements are arranged and a frame area surrounding the radio wave reflection area, and a cover member arranged on the radio wave incident surface side of the metasurface reflector, wherein the frame area includes a first area in which a wiring pattern is formed and a second area in which a terminal portion for connecting to an external circuit is provided, and the cover member includes a first radio wave absorbing pattern provided in an area overlapping with the first area and a second radio wave absorbing pattern provided in an area overlapping with the second area, and in the first area, a conductor pattern is provided between the wiring pattern and the first radio wave absorbing pattern, and the size of the second radio wave absorbing pattern is larger than the size of the first radio wave absorbing pattern.

[0007] FIG. 1 is a schematic exploded perspective view of a radio wave reflecting device according to an embodiment of the present invention. FIG. 2 is a schematic end view of a radio wave reflecting device according to an embodiment of the present invention. FIG. 3 is a schematic end view of a radio wave reflecting device according to an embodiment of the present invention. FIG. 4 is a bottom view of a cover member of a radio wave reflecting device according to an embodiment of the present invention. FIG. 5 is a top view of a radio wave absorbing pattern. FIG. 6 is a schematic exploded perspective view of a radio wave reflecting device according to an embodiment of the present invention. FIG. 7 is a schematic end view of a radio wave reflecting device according to an embodiment of the present invention. FIG. 8 is a schematic end view of a radio wave reflecting device according to an embodiment of the present invention. FIG. 9 is a bottom view of an opposing substrate of a radio wave reflecting device according to an embodiment of the present invention. FIG. 10 is a top view of a radio wave absorbing pattern. FIG. 11 is a top view of a radio wave absorbing pattern. FIG. 12 is a bottom view of a cover member of a radio wave reflecting device according to an embodiment of the present invention. FIG. 13 is a top view of a radio wave absorbing pattern. FIG. 14 is a schematic end view of a radio wave reflecting device according to an embodiment of the present invention. FIG. 1 is a schematic end view of a radio wave reflecting device according to an embodiment of the present invention. FIG. 2 is a cross-sectional view of a simulation model at a non-mounting side of Example 1. FIG. 3 is a cross-sectional view of a simulation model at a mounting side of Example 1. FIG. 4 is a top view of a simulation model of a radio wave absorbing pattern of Example 1. FIG. 5 is a plot showing the frequency dependence of radio wave absorption strength of a simulation model at a non-mounting side of Example 1. FIG. 6 is a plot showing the frequency dependence of radio wave absorption strength of a simulation model at a mounting side of Example 1. FIG. 7 is a cross-sectional view of a simulation model at a non-mounting side of Example 2. FIG. 8 is a cross-sectional view of a simulation model at a mounting side of Example 2. FIG. 9 is a top view of a simulation model of a radio wave absorbing pattern of Example 2. FIG. 10 is a plot showing the frequency dependence of radio wave absorption strength of a simulation model at a non-mounting side of Example 2. FIG. 11 is a plot showing the frequency dependence of radio wave absorption strength of a simulation model at a mounting side of Example 2. FIG. 12 is a cross-sectional view of a simulation model at a non-mounting side of Example 3.1 is a cross-sectional view of a simulation model at a mounting edge of Example 3. FIG. 2 is a top view of a simulation model of a radio wave absorbing pattern of Example 3. FIG. 3 is a plot showing the frequency dependence of radio wave absorption strength of a simulation model at a non-mounting edge of Example 3. FIG. 4 is a plot showing the frequency dependence of radio wave absorption strength of a simulation model at a mounting edge of Example 3. FIG. 5 is a cross-sectional view of a simulation model at a non-mounting edge of Example 4. FIG. 6 is a cross-sectional view of a simulation model at a mounting edge of Example 4. FIG. 7 is a top view of a simulation model of a radio wave absorbing pattern of Example 4. FIG. 8 is a plot showing the frequency dependence of radio wave absorption strength of a simulation model at a non-mounting edge of Example 4. FIG. 9 is a cross-sectional view of a simulation model at a non-mounting edge of Example 5. FIG. 10 is a cross-sectional view of a simulation model at a mounting edge of Example 5. FIG. 11 is a top view of a simulation model of a radio wave absorbing pattern of Example 5. FIG. 12 is a plot showing the frequency dependence of radio wave absorption strength of a simulation model at a non-mounting edge of Example 5.

[0008] Hereinafter, various embodiments of the present invention will be described with reference to the drawings, etc. However, the present invention can be embodied in various forms without departing from the spirit of the present invention, and should not be construed as being limited to the description of the embodiments exemplified below.

[0009] In order to clarify the description, the drawings may show the width, thickness, shape, etc. of each part schematically compared to the actual embodiment, but these are merely examples and do not limit the interpretation of the present invention. In this specification and each drawing, elements having the same functions as those explained in the previous drawings may be assigned the same reference numerals, and duplicate explanations may be omitted.

[0010] In this specification and claims, when expressing an aspect of placing another structure on top of a certain structure, the term "on top" is used, unless otherwise specified, to include both a case where another structure is placed directly on top of a certain structure so as to be in contact with the certain structure, and a case where another structure is placed above a certain structure via yet another structure.

[0011] In this specification and claims, the expression "a structure exposed from another structure" means a state in which a part of a structure is not covered by another structure, and includes a state in which the part not covered by another structure is covered by yet another structure. The state expressed by this expression also includes a state in which a structure is not in contact with another structure.

[0012] In the embodiment of the present invention, when multiple films are formed simultaneously in the same process, these films have the same layer structure, the same material, and the same composition, and therefore these multiple films are defined as existing in the same layer.

[0013] 1. Configuration of the Radio Wave Reflecting Device The configuration of the radio wave reflecting device 100, one embodiment of the present invention, is described below. The radio wave reflecting device 100 can control the direction of radio wave reflection using a metasurface. A metasurface is a type of artificial medium (metamaterial) that achieves arbitrary permittivity and permeability by periodically arranging structures small relative to the wavelength. It is an artificial surface in which the periodic arrangement of the structures is two-dimensional. A metasurface has the characteristic of being able to control the reflection phase of radio waves incident on its surface. The radio wave reflecting device 100 is a so-called liquid crystal radio wave reflecting device, which utilizes the change in permittivity caused by the orientation change of a liquid crystal layer due to an electric field to reflect irradiated radio waves in any direction. There are no restrictions on the wavelength frequency that can be reflected, for example, in the range of 400 MHz to 50 GHz. The radio wave reflecting device 100 can typically be used to reflect radio waves in the 400 MHz to 6.0 GHz band, the 2.5 GHz to 4.7 GHz band, and the 24 GHz to 50 GHz band.

[0014] FIG. 1 shows a schematic exploded perspective view of a radio wave reflecting device 100. The radio wave reflecting device 100 includes a metasurface reflector 170 and a cover member 160. The cover member 160 is disposed on the radio wave incident surface side of the metasurface reflector 170. The metasurface reflector 170 is composed of an array substrate 102, a counter substrate 104, and multiple radio wave reflecting elements 140 arranged in a matrix shape with multiple columns and rows between the array substrate 102 and the counter substrate 104. As will be described in detail later, the radio wave reflecting elements 140 include a driving electrode 142, a common electrode 150, and a liquid crystal layer (not shown) disposed between the driving electrode 142 and the common electrode 150. The liquid crystal layer is sealed by a sealant 152 disposed between the array substrate 102 and the counter substrate 104. In the metasurface reflector 170, the area where the radio wave reflecting elements 140 are disposed (a single rectangular area simultaneously surrounding all of the radio wave reflecting elements) is referred to as the radio wave reflecting area RA. In the radio wave reflection area RA, incident radio waves can be reflected in any direction using the radio wave reflecting element 140. In the metasurface reflector 170, the area surrounding the radio wave reflection area RA is called the frame area FA or the peripheral area.

[0015] The frame area FA of the array substrate 102 is provided with drive circuits (scanning line drive circuit 106, signal line drive circuit 108) for driving the radio wave reflecting elements 140. A plurality of wirings (not shown in FIG. 1 ) are also provided on the array substrate 102. The wirings electrically connect the drive circuits to the radio wave reflecting elements 140, and at least a portion of the wirings extend through the frame area to reach the edge of the array substrate 102. The wirings are exposed at the edge of the array substrate 102 to form a plurality of terminal sections 110. A flexible printed circuit (FPC) board (not shown) is connected to the terminal sections 110. Various drive signals for driving the radio wave reflecting device 100 are supplied from an external circuit via the flexible printed circuit and the terminal sections 110. Based on these signals, the drive circuits generate control signals for controlling the radio wave reflecting elements and supply them to the radio wave reflecting elements. It is also possible to directly supply control signals from an external circuit to the radio wave reflecting elements via wiring, without providing the scanning line drive circuit 106 and / or the signal line drive circuit 108. In this specification and the like, the side of the array substrate 102 on which the terminal section 110 is provided may be referred to as the mounting side, and the other three sides may be referred to as the non-mounting sides.

[0016] In the radio wave reflecting device 100, the frame area FA functions as a frequency selective surface (FSS). A frequency selective surface is a metasurface that functions as a spatial filter by periodically arranging conductor patterns (also called resonant elements) corresponding to specific frequencies on one or both sides of a dielectric material, causing the conductor patterns to resonate with radio waves and allowing only specific frequencies to pass through. The frequency selective surface is composed of a counter substrate 104, a cover member 160, a radio wave absorbing pattern 166 provided between the counter substrate 104 and the cover member 160, and a radio wave absorbing pattern 168 provided in contact with the cover member 160. While FIG. 1 illustrates an example in which the radio wave absorbing pattern 166 is provided on the lower surface of the cover member 160, the radio wave absorbing pattern 166 may also be provided on the upper surface of the counter substrate 104. Furthermore, although the radio wave absorbing pattern 168 is illustrated as being provided on the lower surface of the cover member 160, the radio wave absorbing pattern 168 may be provided on the upper surface of the cover member 160. These configurations will be described in detail below.

[0017] (1) Array substrate, counter substrate, cover member Figures 2 and 3 show schematic end views of the radio wave reflecting device 100. Figures 2 and 3 show schematic end views of a portion of the multiple radio wave reflecting elements 140 provided in the radio wave reflecting area RA and the frame area FA. Figure 2 is a diagram of the scanning line driving circuit 106 and the radio wave reflecting element 140 shown in Figure 1 cut along the D2 direction. Figure 3 is a diagram of the terminal portion 110 and the radio wave reflecting element 140 shown in Figure 1 cut along the D1 direction.

[0018] Dielectric substrates are used for the array substrate 102, the counter substrate 104, and the cover member 160. The array substrate 102 and the counter substrate 104 face each other, imparting physical strength to the radio wave reflecting device 100 and providing a surface on which the radio wave reflecting element 140 is disposed. The cover member 160 is also provided on the counter substrate 104. The cover member 160 imparts physical strength to the radio wave reflecting device 100 and providing a surface on which the radio wave absorbing pattern 168 is disposed. The array substrate 102, the counter substrate 104, and the cover member 160 may contain inorganic insulators such as glass and quartz, semiconductors such as silicon, polymers such as polyimide, polycarbonate, and polyester, and metals such as aluminum, copper, and stainless steel. If a conductive material such as metal is included, it is preferable to provide an undercoat 112 or an overcoat 132 on the surface on which the radio wave reflecting element 140 is disposed, i.e., the surface of the array substrate 102 facing the counter substrate 104 and the surface of the counter substrate 104 facing the array substrate 102. The array substrate 102, the counter substrate 104, and the cover member 160 may or may not transmit visible light. The array substrate 102, the counter substrate 104, and the cover member 160 may be flexible. The array substrate 102 and the counter substrate 104 are fixed to each other by a sealing material 152, either directly or via a first alignment film 144 and a second alignment film 148 (described later). The counter substrate 104 and the cover member 160 are fixed to each other by an adhesive 153.

[0019] 2 and 3, the radio wave reflecting element 140 includes a driving electrode 142, a first alignment film 144 on the driving electrode 142, a liquid crystal layer 146 on the first alignment film 144, a second alignment film 148 on the liquid crystal layer 146, and a common electrode 150 on the second alignment film 148. Radio waves are incident from the common electrode 150 side. Therefore, in the radio wave reflecting element 140, the common electrode 150 functions as a patch electrode.

[0020] Each radio wave reflecting element 140 is connected to an element circuit including at least one transistor 120. Each element circuit may include multiple transistors and may further include one or more capacitive elements. As can be seen from FIGS. 2 and 3 , the element circuit including the transistor 120 and the radio wave reflecting element 140 are provided on the array substrate 102 directly or via an undercoat 112 of any configuration. The transistors included in the element circuit are not limited in structure and may be bottom-gate or top-gate transistors. Alternatively, the transistors may be dual-gate transistors having gate electrodes above and below a semiconductor film. The transistor illustrated in FIG. 2 is a bottom-gate transistor, and is composed of a gate electrode 122, a gate insulating film 124 on the gate electrode 122, a semiconductor film 126 on the gate insulating film 124, and a pair of electrodes 128 and 130 on the semiconductor film 126. A planarization film 116 is provided on the transistor 120, and the radio wave reflecting element 140 is formed thereon. As an optional configuration, interlayer insulating films 114 and 118 may be provided between the transistor 120 and the planarizing film 116 or on the planarizing film 116, respectively.

[0021] The driving electrode 142 of the radio wave reflecting element 140 is electrically connected to the transistor 120 through an opening provided in the interlayer insulating film 118, the planarizing film 116, or the like. Various signals supplied from an external circuit are input to the terminal portion 110 and supplied to the radio wave reflecting element 140 via wiring, either directly or via a driving circuit. As shown in FIGS. 2 and 3 , a wiring pattern 134 is formed in the frame area FA. The wiring pattern 134 includes multiple wires. Although not shown in FIG. 3 , at least a portion of the wiring pattern 134 is connected to the terminal portion 110 and extends over the frame area FA. The wiring pattern 134 may be present in the same layer as the gate electrode 122 or the electrodes 128 and 130. Alternatively, a portion of the wiring pattern 134 may be present in the same layer as the gate electrode 122, and another portion may be present in the same layer as the electrodes 128 and 130.

[0022] As shown in FIG. 3 , a terminal portion 110 is provided outside the sealing material 152 at the edge of the frame area FA. The terminal portion 110 is composed of a conductive layer 154, a conductive layer 155, and a transparent conductive layer 156, which are connected to each other. The conductive layer 154 may be present in the same layer as the gate electrode 122, and the conductive layer 155 may be present in the same layer as the electrodes 128 and 130. The transparent conductive layer 156 is connected to an FPC 158 via an anisotropic conductive layer 157. In the frame area FA, the area where the wiring pattern 134 is formed is also referred to as a first area. The wiring pattern 134 is provided in the vicinity of and surrounding the radio wave reflection area RA. The area where the terminal portion 110 is provided is also referred to as a second area.

[0023] The gate electrode 122, gate insulating film 124, semiconductor film 126, electrodes 128 and 130, interlayer insulating films 114 and 118 and planarizing film 116 covering the transistor 120, wiring pattern 134, and terminal portion 110 can be formed using known materials and by appropriately applying known methods, and detailed description thereof will be omitted. Briefly, the gate electrode 122, electrodes 128 and 130, wiring pattern 134, and terminal portion 110 are formed by forming a film containing a metal such as tantalum, molybdenum, titanium, or aluminum using a sputtering method or a chemical vapor deposition (CVD) method, and then appropriately patterning the film using a photolithography process. The semiconductor film 126 is formed as a film containing a Group 14 element such as silicon, or a film containing an oxide of a Group 13 element such as indium or gallium. The semiconductor film 126 may also be formed by applying a sputtering method or a CVD method. The gate insulating film 124, the interlayer insulating films 114 and 118, the undercoat 112, and the overcoat 132 contain inorganic compounds such as silicon-containing inorganic compounds, such as silicon oxide and silicon nitride, and are formed by applying a sputtering method or a CVD method. The planarizing film 116 contains a polymer, such as an acrylic resin, an epoxy resin, a polyimide, a polyamide, or a silicone resin, and can be formed by appropriately using a wet film-forming method, such as a spin coating method, an inkjet method, or a printing method. By providing the planarizing film 116, the radio wave reflecting element 140 can be formed on a flat surface.

[0024] The driving electrode 142 of the radio wave reflecting element 140 includes, for example, a metal such as copper, aluminum, tungsten, molybdenum, or titanium, or an alloy containing at least one of these metals. Alternatively, the driving electrode 142 may include a light-transmitting conductive oxide such as indium zinc oxide (IZO) or indium tin oxide (ITO). The driving electrode 142 may have a single-layer structure or a layered structure in which layers of different compositions are stacked. For example, a layered structure of a layer containing a conductive oxide and a layer containing the above-mentioned metal or alloy may be employed. Alternatively, the driving electrode 142 may have a mesh shape to impart light transmittance to the driving electrode 142 containing a metal or alloy.

[0025] The first alignment film 144 provided on the plurality of drive electrodes 142 is provided to control the alignment of liquid crystal molecules constituting the liquid crystal layer 146 provided thereon. The first alignment film 144 can be provided continuously across the plurality of radio wave reflecting elements 140. In other words, the first alignment film 144 can be provided so as to be shared by all of the radio wave reflecting elements 140 without being divided between adjacent radio wave reflecting elements 140.

[0026] The first alignment film 144 includes a polymer such as polyimide or polyester. The first alignment film 144 is formed by using a wet film formation method such as an inkjet method, a spin coating method, a printing method, or a dip coating method, and its surface is subjected to a rubbing treatment. Alternatively, the first alignment film 144 may be formed by a photo-alignment treatment.

[0027] The liquid crystal layer 146 is sealed between the array substrate 102 and the counter substrate 104 by a sealant 152. The structure of the liquid crystal molecules contained in the liquid crystal layer 146 is not limited. Therefore, the liquid crystal molecules may be nematic liquid crystal, smectic liquid crystal, cholesteric liquid crystal, or chiral smectic liquid crystal. The thickness of the liquid crystal layer 146 is, for example, 10 μm to 100 μm, preferably 20 μm to 60 μm. Although not shown, spacers may be provided within the liquid crystal layer 146 to maintain this thickness throughout the entire radio wave reflecting device 100. Note that if the above-described thickness of the liquid crystal layer 146 is adopted in a liquid crystal display device, the high response required for displaying moving images cannot be obtained, and it becomes extremely difficult to demonstrate the functions of the liquid crystal display device.

[0028] The second alignment film 148 is also provided to control the alignment of the liquid crystal molecules, and has a configuration similar to that of the first alignment film 144. The second alignment film 148 can also be formed so as to be continuous across adjacent radio wave reflecting elements 140 and shared by a plurality of radio wave reflecting elements 140. The first alignment film 144 and the second alignment film 148 are arranged so that the direction in which the first alignment film 144 aligns the liquid crystal molecules is parallel to that of the second alignment film 148. The first alignment film 144 and the second alignment film 148 align the liquid crystal molecules in a certain direction.

[0029] A common electrode 150 is provided for each radio wave reflecting element 140. Therefore, the common electrodes 150 are also arranged in a matrix shape with multiple rows and columns, and the common electrode 150 overlaps the driving electrode 142 in each radio wave reflecting element 140. As described above, radio waves are incident on the common electrode 150 side. Therefore, the common electrode 150 preferably has a highly symmetrical shape, such as a regular polygon or a circle, to efficiently reflect both orthogonal components of the radio wave (vertically polarized wave and horizontally polarized wave). The size of the common electrode 150 can be adjusted appropriately depending on the wavelength of the radio wave to be reflected. For example, the row and column lengths may be selected appropriately from a range of 1 mm to 40 mm. Although not shown, the multiple common electrodes 150 are electrically connected to each other in the column and / or column directions by connecting wiring. A constant potential (common potential) is supplied to the common electrode 150 directly from an external circuit or via the signal line driving circuit 108.

[0030] Like the driving electrode 142, the common electrode 150 may also contain a metal such as copper, aluminum, tungsten, molybdenum, or titanium, an alloy containing at least one of these metals, or a conductive oxide such as ITO or IZO. The common electrode 150 may also have a single-layer structure or a laminated structure in which layers of different compositions are stacked. The common electrode 150 may also be formed by applying a sputtering method, a CVD method, or the like. Note that the radio wave reflecting element 140 may or may not transmit visible light. For example, visible light may be blocked by using a metal or alloy having a thickness that does not transmit visible light for the driving electrode 142 and the common electrode 150.

[0031] In the radio wave reflecting device 100, as described above, the directions in which the first alignment film 144 and the second alignment film 148 align the liquid crystal molecules are parallel. Therefore, when no potential difference is applied between the drive electrode 142 and the common electrode 150, no vertical electric field is generated in the liquid crystal layer 146, and the liquid crystal molecules are horizontally aligned. The orientation of the liquid crystal layer 146 is the same between the radio wave reflecting elements 140, and therefore the dielectric constant is also constant within the liquid crystal layer 146. As a result, the spread (phase) of the reflected wave generated when a radio wave incident from the common electrode 150 side is reflected by the surface of the common electrode 150 does not change. As a result, the incident radio wave is specularly reflected by the radio wave reflecting device 100, and a reflected wave is generated at an output angle that is the same as the angle of incidence.

[0032] In contrast, when the voltage applied to the drive electrode 142 is controlled using an element circuit to create a potential difference between the drive electrode 142 and the common electrode 150, the liquid crystal molecules rise and become vertically oriented due to the generated vertical electric field. At this time, if vertical electric fields of different strengths are generated between the radio wave reflecting elements 140, the dielectric constant of the liquid crystal layer 146 changes between the radio wave reflecting elements 140 depending on the strength of the vertical electric field. As a result, the phase of the reflected wave changes, and accordingly, the reflection direction of the radio wave incident on the radio wave reflecting area RA can be changed. The reflection direction can be freely controlled by changing the strength of the vertical electric field formed in the radio wave reflecting element 140.

[0033] (3) Frequency Selective Surface As described above, the frame area FA of the radio wave reflecting device 100 is provided with a wiring pattern 134 for supplying various signals. A drive circuit may also be disposed in the frame area FA. Because structures such as the wiring pattern 134 and drive circuitry provided on the array substrate 102 also reflect radio waves, the radio waves reflected by the radio wave reflecting device 100 include not only the desired reflected waves obtained in the radio wave reflecting area RA but also radio waves reflected in the frame area FA. Furthermore, the radio waves reflected in the frame area FA cannot be controlled. This reduces the amplitude of the reflected waves, resulting in poor reflection characteristics.

[0034] Therefore, by arranging a plurality of radio wave absorbing patterns 166 as a frequency selective surface so as to surround the radio wave reflecting area RA of the frame area FA, it is possible to effectively absorb radio waves incident on the frame area FA. As a result, radio waves incident on the radio wave reflecting device 100 can be selectively reflected by the radio wave reflecting area RA, and excellent reflection characteristics with reduced reflection loss of reflected waves can be obtained.

[0035] On the other hand, as a frequency selective surface, the structures formed on the array substrate 102 in the frame area FA near the radio wave reflection area RA and the area where the terminal section 110 is provided are different. That is, the wiring pattern 134 and the drive circuit are provided near the radio wave reflection area RA, while the area where the terminal section 110 is provided is provided with not only various wiring but also the terminal section 110 and the flexible printed circuit board 158. Furthermore, the counter substrate 104 is not provided above the terminal section 110 but is exposed. That is, when the radio wave reflecting device 100 is viewed in cross section, the counter substrate 104 overlaps the array substrate 102 in the area near the radio wave reflection area RA, whereas in the area where the terminal section 110 is provided, the counter substrate 104 is not provided above the array substrate 102 but is exposed. This means that the dielectric constant of the structures is different between the area near the radio wave reflection area RA and the area where the terminal section 110 is provided when the radio wave reflecting device 100 is viewed in cross section. In this way, in areas with different structures, simply arranging multiple radio wave absorbing patterns 166 to surround the radio wave reflection area RA in the frame area FA may not result in the desired absorption characteristics being obtained on any of the four sides.

[0036] Therefore, it is preferable to not only arrange multiple radio wave absorbing patterns 166 so as to overlap the area near the radio wave reflection area RA, but also to provide multiple radio wave absorbing patterns 168 so as to overlap the area where the terminal portion 110 is provided. The terminal portion 110 is provided in an area exposed from the opposing substrate 104. Therefore, as a frequency selective surface, a cover member 160 is provided on the opposing substrate 104 so as to overlap the terminal portion 110, and a radio wave absorbing pattern 168 is provided at a position on the cover member 160 that overlaps with the terminal portion 110. In this case, it is preferable to make the size of the radio wave absorbing pattern 166 different from the size of the radio wave absorbing pattern 168. For example, the size of the radio wave absorbing pattern 168 is made larger than the size of the radio wave absorbing pattern 166. The radio wave absorbing pattern 166 is in contact with a dielectric. One side of the radio wave absorbing pattern 168 is in contact with the dielectric, and the other side is in contact with air. The dimensions of the radio wave absorbing patterns 166 and 168 are appropriately designed to match the wavelength of the target radio waves, but a difference occurs in the dielectric constant experienced by the radio waves near the radio wave absorbing patterns 166 and 168. By making the size of the radio wave absorbing pattern 168 larger than the size of the radio wave absorbing pattern 166, the radio wave reflecting device 100 exhibits excellent radio wave absorption characteristics at the frequency selective surface, and as a result, the reflection amplitude of the radio wave reflecting device 100 can be improved. The radio wave absorbing patterns 166 and 168 will be described in detail below.

[0037] 4 is a layout diagram of multiple radio wave absorbing patterns 166, 168 provided on the cover member 160. The radio wave absorbing pattern 166 is provided so as to overlap the frame area FA of the array substrate 102 and also so as to overlap at least a portion of the wiring pattern 134 on the frame area FA. The radio wave absorbing pattern 166 is arranged in the frame area FA so as to overlap the sealing material 152 that is arranged to surround the radio wave reflection area RA. While FIG. 4 illustrates an example in which the multiple radio wave absorbing patterns 166 are arranged to surround the four sides of the radio wave reflection area RA, the present invention is not limited to this. A configuration may also be adopted in which no radio wave absorbing pattern 166 is provided on one side on the terminal portion 110 side, and multiple radio wave absorbing patterns 166 are provided on the other three sides.

[0038] Each of the multiple radio wave absorbing patterns 166 is at least one electrically floating conductive layer. Each radio wave absorbing pattern 166 may be composed of a single conductive layer, or may include n conductive layers (n is an integer of 2 or more). Fig. 5A shows an example of a radio wave absorbing pattern 166 composed of a single L-shaped conductive layer. Although it depends on the wavelength of the radio wave to be reflected, the length L of the mutually orthogonal arms (two straight portions present via a bent portion) of the radio wave absorbing pattern 166 is １ The length L of the arm may be appropriately selected from the range of, for example, 0.5 mm or more and 2.0 mm or less, and the width W of the arm may be appropriately selected from the range of, for example, 0.1 mm or more and 0.5 mm or less. It is preferable that the two arms are arranged so as to be perpendicular to each other. １ is the length that contributes to the resonance of radio waves. In addition, since the L-shaped conductive layer can be said to be composed of two orthogonal conductive layers, each radio wave absorbing pattern 166 can absorb both polarized waves. Therefore, the arrangement direction of the L-shaped conductive layers may be the same among multiple radio wave absorbing patterns 166.

[0039] The multiple radio wave absorbing patterns 168 are provided in an area that overlaps the frame area FA of the array substrate 102 but does not overlap the counter substrate 104. Each of the multiple radio wave absorbing patterns 168 is at least one electrically floating conductive layer. Each radio wave absorbing pattern 168 may be composed of a single conductive layer, or may include n conductive layers (n is an integer of 2 or greater). Figure 5B shows an example of a radio wave absorbing pattern 168 composed of a single L-shaped conductive layer.

[0040] Here, it is preferable that the shape of the radio wave absorbing pattern 166 is the same as the shape of the radio wave absorbing pattern 168. When the shape of the radio wave absorbing pattern 166 is L-shaped, it is preferable that the shape of the radio wave absorbing pattern 168 is also L-shaped. However, it is preferable that the size of the radio wave absorbing pattern 168 is larger than the size of the radio wave absorbing pattern 166. The length L of the arm of the L-shaped conductive layer ２ is the length of the side that contributes to the resonance of the radio wave. As will be explained in detail later, the length L of the radio wave absorbing pattern 168 ２ is the length L of the radio wave absorbing pattern 166 １ For example, the length L２ and length L １ In this case, the width W of the arm of the radio wave absorbing pattern 166 and the width W of the arm of the radio wave absorbing pattern 168 may be the same because they do not contribute to the resonance of radio waves.

[0041] Pitch P of the radio wave absorbing pattern 166 １ (See FIG. 4) Although it also depends on the wavelength of the radio wave to be reflected, it may be selected appropriately from the range of 0.4 mm to 3.0 mm. １ is the pitch P of the driving electrodes 142 or the common electrode 150 ３ 4 , a pair of radio wave absorbing patterns 166 sandwiching a plurality of radio wave reflecting elements 140 therebetween can be arranged in each row. Furthermore, the same number of radio wave absorbing patterns 166 as the number of columns can be arranged in the row direction at positions corresponding to each column. In the example shown in FIG. 4 , if the number of rows in the matrix shape formed by the plurality of driving electrodes 142 is N and the number of columns is M, the number of radio wave absorbing patterns 166 is (2N + 2M). However, the arrangement of the radio wave absorbing patterns 166 is not limited to the above arrangement. Although not shown in FIG. 4 , radio wave absorbing patterns 166 may also be arranged at corners indicated by C, that is, at positions where the arrangement direction of the radio wave absorbing patterns 166 arranged in the row direction intersects with the arrangement direction of the radio wave absorbing patterns 166 arranged in the column direction. In this case, the radio wave absorbing patterns 166 may be arranged so that the repeating pattern of the radio wave absorbing patterns 166 arranged in the row direction and the repeating pattern of the radio wave absorbing patterns 166 arranged in the column direction are consistent with each other.

[0042] Pitch P of the radio wave absorbing pattern 168 ２ (see FIG. 4) may be appropriately selected from the range of 0.4 mm to 3.0 mm, for example, in the same way as the radio wave absorbing pattern 166. For example, １The radio wave absorbing pattern 168 may be the same as or substantially the same as the radio wave absorbing pattern 168. The radio wave absorbing pattern 168 is provided in an area overlapping the terminal portion 110 in the frame area FA. As shown in Fig. 4, M radio wave absorbing patterns 168 are provided, the number of which is the same as the number of columns in which the radio wave reflecting elements 140 are provided. Although Fig. 4 illustrates an example in which one row of the radio wave absorbing pattern 168 is provided, the number of rows may be appropriately selected according to the size of the terminal portion 110 in the frame area FA, and multiple rows may be provided.

[0043] By adopting the above-described shape and arrangement, the radio wave absorbing patterns 166, 168 selectively absorb radio waves of desired wavelengths, as shown in the simulation results described in the examples. As a result, radio wave reflection in the frame area FA can be suppressed, and radio waves can be selectively reflected in the radio wave reflecting area RA. The radio wave reflecting device 100 can achieve excellent reflection characteristics with suppressed reflection loss of reflected waves.

[0044] (Modifications) The configuration of the radio wave reflecting device 100 according to the embodiment of the present invention is not limited to the configuration described above, and various modifications are possible. Modifications of the radio wave reflecting device 100 will be described below.

[0045] (1) Frequency Selective Surface Fig. 6 shows a schematic exploded perspective view of the radio wave reflecting device 100A. As shown in Fig. 6, a frame area FA is provided so as to surround the radio wave reflecting area RA. The frame area FA shown in Fig. 6 functions as a frequency selective surface. In addition to a radio wave absorbing pattern 166 provided between the counter substrate 104 and the cover member 160 and a radio wave absorbing pattern 168 provided in contact with the counter substrate 104, a conductor pattern 172 is also provided on the frequency selective surface. The other configurations are the same as those of the radio wave reflecting device 100 shown in Fig. 1, and therefore detailed description thereof will be omitted.

[0046] 7 and 8 show schematic end views of the radio wave reflecting device 100A. Fig. 7 is a cross-sectional view of the scanning line driving circuit 106 and the radio wave reflecting element 140 shown in Fig. 6 taken along the direction D2. Fig. 8 is a cross-sectional view of the terminal portion 110 and the radio wave reflecting element 140 shown in Fig. 6 taken along the direction D1.

[0047] The radio wave reflecting device 100 has a radio wave absorbing pattern 166 provided between the counter substrate 104 and the cover member 160, and a radio wave absorbing pattern 168 provided in contact with the counter substrate 104. In Fig. 6, the radio wave absorbing pattern 166 is illustrated as being provided on the lower surface of the cover member 160, but the radio wave absorbing pattern 166 may be provided on the upper surface of the counter substrate 104. Furthermore, the radio wave absorbing pattern 168 is illustrated as being provided on the lower surface of the cover member 160, but the radio wave absorbing pattern 168 may be provided on the upper surface of the cover member 160.

[0048] The conductor pattern 172 is provided on the lower surface side of the counter substrate 107, i.e., on the side where the liquid crystal layer is provided, and overlaps part of the wiring pattern 134. The conductor pattern 172 also overlaps the sealing material 152. The conductor pattern 172 overlaps the radio wave absorbing pattern 166 with the counter substrate 104 interposed therebetween.

[0049] The conductor pattern 172 may include a conductive oxide such as ITO or IZO, or may include a metal such as copper, aluminum, tungsten, molybdenum, or titanium, or an alloy containing at least one of these metals. Preferably, the conductor pattern 172 may be configured to include a highly conductive metal such as titanium, molybdenum, or tungsten so that the frequency selective surface exhibits high radio wave absorption characteristics. The conductor pattern 172 may be formed in the same process as the common electrode 150. Like the common electrode 150, the conductor pattern 172 may be covered with the second alignment film 148. The conductor pattern 172 may be electrically floating or may have a constant potential (common potential) applied to it. In the latter case, the potential applied to the conductor pattern 172 may be the same as the potential applied to the common electrode 150.

[0050] FIG. 9 is a layout diagram of a conductor pattern 172 arranged on the underside of the counter substrate 104. The conductor pattern 172 is formed of a single conductive layer so as to surround all four sides of the radio wave reflection area RA. The conductor pattern 172 is also arranged so as to overlap the frame area FA of the array substrate 102 and at least a portion of the wiring pattern 134 on the frame area FA. Although not shown in FIG. 9 , the conductor pattern 172 overlaps the radio wave absorbing pattern 166 via the counter substrate 104. The conductor pattern 172 does not overlap the terminal section 110. While FIG. 9 illustrates an example in which the conductor pattern 172 is arranged so as to surround all four sides of the radio wave reflection area RA, the present invention is not limited to this. A configuration in which no conductor pattern 172 is provided on one side of the terminal section 110, and multiple conductor patterns 172 are provided on the other three sides, may also be used. In this case, the plurality of radio wave absorbing patterns 166 may be provided on the other three sides instead of on the one side on the terminal portion 110 side. Furthermore, in the frame area FA, if the configuration of the upper side and the left and right sides of the other three sides is different, it is preferable to change the width of the conductor pattern 172 as well.

[0051] By providing the conductor pattern 172 in the area of ​​the frequency selective surface that overlaps with the radio wave absorbing pattern 166, the radio wave reflecting device 100A can selectively absorb radio waves of a desired wavelength more than the radio wave reflecting device 100. As a result, radio wave reflection in the frame area FA can be suppressed and radio waves can be selectively reflected in the radio wave reflecting area RA. The radio wave reflecting device 100A can achieve excellent reflection characteristics with suppressed reflection loss of reflected waves.

[0052] (2) Radio Wave Absorbing Pattern The shapes of the radio wave absorbing patterns 166, 168 are not limited to those shown in FIGS. 5A and 5B. As shown in FIGS. 10A and 10B, the radio wave absorbing patterns 166, 168 may be configured using multiple rectangular conductive layers. As shown in FIG. 5A, the radio wave absorbing pattern 166 is configured using multiple rectangular conductive layers 166-1, 166-2, as shown in FIG. 10A. The rectangular conductive layers 166-1, 166-2 are arranged parallel to each other. That is, the rectangular conductive layers 166-1, 166-2 are arranged so that their longitudinal directions are parallel to each other. At the same time, in each radio wave absorbing pattern 166, the multiple rectangular conductive layers 166-1, 166-2 are arranged so that they overlap each other in the direction perpendicular to the longitudinal direction (short direction). In each radio wave absorbing pattern 166, it is preferable to arrange the plurality of rectangular conductive layers 166-1, 166-2 so that the centers (or centers of gravity) of all the rectangular conductive layers 166-1, 166-2 are positioned on the same straight line perpendicular to the longitudinal direction.

[0053] Furthermore, the rectangular conductive layers 166-1 and 166-2 are configured to have different lengths (lengths in the longitudinal direction). ２ Although it depends on the wavelength of the radio wave to be reflected, it can be selected from the range of 0.5 mm to 1.6 mm, for example. １ The length L can be selected from the range of, for example, 0.5 mm or more and 2.0 mm or less. １ and L ２ The difference also depends on the wavelength of the radio wave to be reflected, but may be set to, for example, 0.1 mm or more and 0.3 mm or less.

[0054] Width (length in the short direction) W of the rectangular conductive layers 166-1 and 166-2 １ , W ２ Although it depends on the wavelength of the radio wave to be reflected, it may be selected, for example, from the range of 0.05 mm to 2.0 mm. １ , W ２For example, when each radio wave absorbing pattern 166 has two rectangular conductive layers 166-1 and 166-2, the width W １ and width W ２ may be the same or different (see FIG. 10A).

[0055] Furthermore, in the radio wave absorbing pattern 166, the distance D between the adjacent rectangular conductive layer 166-1 and rectangular conductive layer 166-2 is also adjusted appropriately according to the wavelength of the radio waves to be reflected. For example, the distance D can be selected from the range of 0.2 mm to 1.0 mm. Note that the distance D is the distance in the short side direction of the rectangular conductive layer between the center (or center of gravity) of the adjacent rectangular conductive layer 166-1 and the center of the rectangular conductive layer 166-2.

[0056] 10B, the radio wave absorbing pattern 168 also has rectangular conductive layers 168-1 and 168-2, similar to the radio wave absorbing pattern 166. As explained in FIGS. 5A and 5B, the size of the radio wave absorbing pattern 168 is preferably larger than the size of the radio wave absorbing pattern 166. Specifically, it is preferable that the length contributing to the resonance of the radio wave is large. Therefore, the length L of the rectangular conductive layer 168-1 ３ and the length L of the rectangular conductive layer 168-2 ４ is the length L １ , L ２ The width W of the rectangular conductive layers 168-1 and 168-2 is preferably 1.1 times or more and 1.8 times or less, and more preferably 1.3 times or more and 1.5 times or less. １ , W ２ is the width W of the rectangular conductive layers 166-1 and 166-2 １ , W ２ It is preferable that the length is the same as

[0057] Furthermore, when multiple radio wave absorbing patterns 166 are arranged in the frame region, it is preferable to arrange them so that the longitudinal directions of the rectangular conductive layers 166-1 and 166-2 are perpendicular to each other between adjacent rectangular conductive layers 166-1 and 166-2. As shown in FIG. 11, it is preferable to arrange multiple radio wave absorbing patterns 166 so that the longitudinal directions of the rectangular conductive layers alternate. By adopting such an arrangement, it is possible to effectively absorb both vertically polarized waves and horizontally polarized waves. Note that, when absorbing only vertically polarized waves or horizontally polarized waves, the longitudinal directions of the rectangular conductive layers 166-1 and 166-2 in all radio wave absorbing patterns 166 may be parallel to each other, or the longitudinal directions of the rectangular conductive layers 168-1 and 168-2 in all radio wave absorbing patterns 168 may be parallel to each other.

[0058] As shown in Figures 12A and 12B, the radio wave absorbing patterns 166, 168 may be formed by an annular conductive layer. As shown in Figure 12A, the radio wave absorbing pattern 166 is formed by an annular conductive layer with a radius r1. The radius r1 is preferably 0.2 mm or more and 2.0 mm or less. As shown in Figure 12B, the radio wave absorbing pattern 168 is formed by an annular conductive layer with a radius r2. The radii r1 and r2 are lengths that contribute to the resonance of radio waves. As with the other shapes of the radio wave absorbing patterns 166, 168, the radius r2 is preferably larger than the radius r1. The radius r2 is preferably 1.1 times or more and 1.8 times or less, more preferably 1.3 times or more and 1.5 times or less, of the radius r1. The radio wave absorbing patterns 166, 168 may have the same ring width W. The ring width W may be 0.2 mm or more and 1.0 mm or less.

[0059] (3) Arrangement of Metasurface In the radio wave reflecting device 100 having the above-described configuration, an example is shown in which the radio wave absorbing pattern 168 is provided on the underside of the cover member 160, but the position of the radio wave absorbing pattern 168 is not limited to that in the above-described configuration. Figures 13A to 15B list examples of the arrangement of the radio wave absorbing patterns 166, 168 in the radio wave reflecting device 100.

[0060] As shown in FIG. 13A , the radio wave absorbing pattern 166 may be disposed between the counter substrate 104 and the cover member 160, and the radio wave absorbing pattern 168 may be disposed on the upper side of the cover member 160. In this case, the upper side of the counter substrate 104 on which the radio wave absorbing pattern 166 is formed may be bonded to the lower side of the cover member 160 on which the radio wave absorbing pattern 168 is formed using an adhesive 153. Alternatively, the lower side of the cover member 160 on which the radio wave absorbing pattern 168 is formed on its upper side and the radio wave absorbing pattern 166 is formed on its lower side may be bonded to the upper side of the counter substrate 104 using the adhesive 153. Furthermore, as shown in FIG. 13B , the radio wave absorbing pattern 166 may be provided on the upper side of the cover member 160, and the radio wave absorbing pattern 168 may be provided on the lower side of the cover member 160. In this case, the lower side of the cover member 160 on which the radio wave absorbing pattern 166 is formed on its upper side and the radio wave absorbing pattern 168 is formed on its lower side may be bonded to the upper side of the counter substrate 104 using the adhesive 153.

[0061] 14A , the radio wave absorbing patterns 166 and 168 may be provided on the upper side of the cover member 160. In this case, the lower side of the cover member 160, on which the radio wave absorbing patterns 166 and 168 are formed, may be bonded to the upper side of the counter substrate 104 with an adhesive 153. Also, as shown in FIG. 14B , a conductor pattern 172 may be provided on the lower surface of the counter substrate 104 so as to surround the radio wave reflection area RA, thereby forming a frequency selective surface. For the planar layout of the conductor pattern 172, see FIG. 9 . In this case, the upper side of the counter substrate 104, on which the radio wave absorbing pattern 166 is formed, may be bonded to the lower side of the cover member 160, on which the radio wave absorbing pattern 168 is formed, with the adhesive 153. Alternatively, the lower side of the cover member 160, on which the radio wave absorbing pattern 168 is formed on the upper side and the radio wave absorbing pattern 166 is formed on the lower side, may be bonded to the upper side of the counter substrate 104 with the adhesive 153.

[0062] 15A , a frequency selective surface may be formed by providing a conductor pattern 172 on the lower surface of the counter substrate 104 so as to surround the radio wave reflection region RA, and a radio wave absorbing pattern 166 may be provided on the upper side of the cover member 160, and a radio wave absorbing pattern 168 may be provided on the lower side of the cover member 160. In this case, the lower side of the cover member 160, on which the radio wave absorbing pattern 166 is formed on the upper side and the radio wave absorbing pattern 168 is formed on the lower side, may be bonded to the upper side of the counter substrate 104 with an adhesive 153. Also, as shown in FIG. 15B , a frequency selective surface may be formed by providing a conductor pattern 172 on the lower surface of the counter substrate 104 so as to surround the radio wave reflection region RA, and the radio wave absorbing patterns 166, 168 may be provided on the upper side of the cover member 160. In this case, the lower side of the cover member 160, on which the radio wave absorbing patterns 166, 168 are formed on the upper side, may be bonded to the upper side of the counter substrate 104 with an adhesive 153.

[0063] By adopting the configuration shown in Figures 13A to 15B described above, radio waves incident on the frame area FA from the array substrate 102 side can be absorbed by the radio wave absorbing patterns 166, 168, thereby providing a radio wave reflecting device 100 with excellent reflection characteristics.

[0064] In this example, the results of a simulation analysis of the influence that the difference in the shape of the radio wave absorbing pattern on the non-mounting side and the mounting side has on the radio wave absorbing characteristics will be described.

[0065] 1. Example 1 Figures 16A to 16C show a simulation model of a radio wave reflecting device in Example 1. Figure 16A is a cross-sectional view of the simulation model at the non-mounting edge, Figure 16B is a cross-sectional view of the simulation model at the mounting edge, and Figure 16C is a top view of the radio wave absorbing pattern. In Figures 16A to 16C, a radio wave absorbing pattern 174 is provided on the underside of the cover member 160 on both the non-mounting edge and the mounting edge. The upper side of Figures 16A and 16B is the radio wave incident side. The thickness of the opposing substrate 104 and the cover member 160 was set to 0.5 mm, and the dielectric constant was set to 5.4, which is the relative dielectric constant of glass. Three patterns of simulation were performed by changing the length L of the radio wave absorbing pattern 174. The basic shape of the radio wave absorbing pattern 174 was set to a length L of 1.15 mm and a width of 0.40 mm. Moreover, the length L of the radio wave absorbing pattern 174 was set to 1.60 mm and W to 0.40 mm, with only the length L of the side that contributes to the resonance of radio waves being extended from the basic shape of the radio wave absorbing pattern 174. Furthermore, as a figure similar to the basic shape of the radio wave absorbing pattern 174, the length L of the radio wave absorbing pattern 174 was set to 1.60 mm and W to 0.56 mm (omitted below). The simulation was performed under conditions in which the radio wave absorbing pattern 174 was exposed to air.

[0066] FIG. 17 shows the simulation results for the non-mounted edge, and FIG. 18 shows the simulation results for the mounted edge. The horizontal axis of the graphs shown in FIGS. 17 and 18 represents frequency, and the vertical axis represents the attenuation of the amplitude of the reflected wave in common logarithm. The smaller the amplitude of the reflected wave, the stronger the absorption of the radio wave. At a frequency of 47 GHz, as shown in FIG. 17 , it can be seen that the radio wave is strongly absorbed on the non-mounted edge when the radio wave absorbing pattern 174 has its basic shape. Also, as shown in FIG. 18 , it can be seen that the radio wave is strongly absorbed on the mounted edge when the radio wave absorbing pattern 174 has a shape that extends the edge that contributes to radio wave resonance. As shown in FIGS. 17 and 18 , it can be seen that using radio wave absorbing patterns with the same shape on the non-mounted edge and the mounted edge results in different frequencies showing the resonance peak. Therefore, it is preferable to use radio wave absorbing patterns with different shapes on the non-mounted edge and the mounted edge. Furthermore, it is preferable that the radio wave absorbing patterns on the non-mounting side and the mounting side are not similar in shape, but are shaped such that only the length of the side that contributes to the resonance of the radio waves is longer.

[0067] The simulation conditions and the results of the reflection amplitudes on the non-mounted sides and mounted sides are shown in Table 1. This suggests that it is possible to strongly absorb radio waves by using the radio wave absorbing pattern as the basic shape on the non-mounted sides, and by using a shape on the mounted sides where only the length of the side that contributes to radio wave resonance is longer than the basic shape.

[0068]

[0069] 2. Example 2 Figures 19A to 19C show a simulation model of a radio wave reflecting device in Example 2. Figure 19A is a cross-sectional view of the simulation model at the non-mounting edge, Figure 19B is a cross-sectional view of the simulation model at the mounting edge, and Figure 19C is a top view of the radio wave absorbing pattern. The configurations shown in Figures 19B and 19C are similar to the configurations shown in Figures 16A and 16B. The difference from the configuration shown in Figure 16A is that in the simulation model at the non-mounting edge shown in Figure 19A, a conductive layer 176 (corresponding to the conductor pattern 172) is provided on the underside of the opposing substrate 104. The other configurations and simulation conditions are similar to the configurations and simulation conditions described with reference to Figures 16A to 16C.

[0070] FIG. 20 shows the simulation results for the non-mounted edge, and FIG. 21 shows the simulation results for the mounted edge. The horizontal axis of the graphs shown in FIGS. 20 and 21 represents frequency, and the vertical axis represents the attenuation of the amplitude of the reflected wave in common logarithm. The smaller the amplitude of the reflected wave, the stronger the absorption of the radio wave. At a frequency of 47 GHz, as shown in FIG. 20 , it can be seen that the radio wave is strongly absorbed on the non-mounted edge when the radio wave absorbing pattern 174 has its basic shape. Also, as shown in FIG. 21 , it can be seen that the radio wave is strongly absorbed on the mounted edge when the radio wave absorbing pattern 174 has a shape that extends the edge that contributes to radio wave resonance. As in Example 1, it can be seen that using radio wave absorbing patterns with the same shape on the non-mounted edge and the mounted edge results in a change in the frequency at which the resonance peak occurs. Therefore, it is preferable to use radio wave absorbing patterns with different shapes on the non-mounted edge and the mounted edge. Furthermore, it is preferable that the radio wave absorbing patterns on the non-mounted edge and the mounted edge are not similar in shape, but are shaped such that only the edge that contributes to radio wave resonance is longer.

[0071] Table 2 shows the simulation conditions and the results of the reflection amplitudes at the non-mounted edge and the mounted edge. This suggests that strong radio waves can be absorbed by using the radio wave absorbing pattern as the basic shape at the non-mounted edge and by using a shape at the mounted edge that is longer than the basic shape only for the edges that contribute to radio wave resonance. Furthermore, comparing Fig. 16A with Fig. 19A, Fig. 19A shows that a conductive layer 176 is provided at the non-mounted edge. Comparing Fig. 18 with Fig. 21, it can be seen that stronger radio waves are absorbed by sandwiching the non-mounted edge of the opposing substrate 104 between the radio wave absorbing pattern 166 and the conductive layer 176.

[0072]

[0073] 22A to 22C show a simulation model of a radio wave reflecting device in Example 3. FIG. 22A is a cross-sectional view of the simulation model at the non-mounting side, FIG. 22B is a cross-sectional view of the simulation model at the mounting side, and FIG. 22C is a top view of the radio wave absorbing pattern. The configurations shown in FIGS. 22A and 22B are similar to the configurations shown in FIGS. 16A and 16B. The difference from the configuration shown in FIG. 16C is that the shape of the radio wave absorbing pattern 174 shown in FIG. 22C is composed of two rectangular conductive layers 174-1 and 174-2. The basic shape of the radio wave absorbing pattern 174 is a rectangular conductive layer 174-1 with a length L １ is set to 1.20 mm, and W １ is 0.10 mm, and the length L of the rectangular conductive layer 174-2 ２ The length of the rectangular conductive layer 174-1 is set to 1.08 mm, and W2 is set to 0.10 mm. １ is set to 1.56 mm, and W １ is 0.10 mm, and the length L of the rectangular conductive layer 174-2 ２ is set to 1.44 mm, and W ２ The length L of the rectangular conductive layer 174-1 is set to 0.10 mm. １ is set to 1.56 mm, and W １ is 0.13 mm, and the length L of the rectangular conductive layer 174-2 ２ is set to 1.44 mm, and W ２The other configurations and simulation conditions were the same as those described with reference to FIGS. 16A to 16C.

[0074] FIG. 23 shows the simulation results for the non-mounted edge, and FIG. 24 shows the simulation results for the mounted edge. The horizontal axis of the graphs shown in FIGS. 23 and 24 represents frequency, and the vertical axis represents the attenuation of the amplitude of the reflected wave in common logarithm. A smaller amplitude of the reflected wave indicates stronger absorption of the radio wave. At a frequency of 47 GHz, as shown in FIG. 23 , it can be seen that, on the non-mounted edge, when the radio wave absorbing pattern 174 has a basic shape, radio waves are strongly absorbed. Also, as shown in FIG. 24 , it can be seen that, on the mounted edge, when the radio wave absorbing pattern 174 has a shape that extends the edge that contributes to radio wave resonance, radio waves are strongly absorbed. As in Example 1, it can be seen that using radio wave absorbing patterns with the same shape on the non-mounted edge and the mounted edge results in a change in the frequency at which the resonance peak occurs. Therefore, it is preferable to use radio wave absorbing patterns with different shapes on the non-mounted edge and the mounted edge. Furthermore, it is preferable that the radio wave absorbing patterns on the non-mounted edge and the mounted edge are not similar in shape, but rather have a shape in which only the edge that contributes to radio wave resonance is longer.

[0075] Table 3 shows the simulation conditions and the results of the reflection amplitudes on the non-mounted sides and mounted sides. This suggests that it is possible to strongly absorb radio waves by using the radio wave absorbing pattern as the basic shape on the non-mounted sides, and by using a shape on the mounted sides where only the length of the side that contributes to radio wave resonance is longer than the basic shape.

[0076]

[0077] 4. Example 4 Figures 25A to 25C show a simulation model of a radio wave reflecting device in Example 5. Figure 25A is a cross-sectional view of the simulation model at the non-mounting side, Figure 25B is a cross-sectional view of the simulation model at the mounting side, and Figure 25C is a top view of the radio wave absorbing pattern. The configurations shown in Figures 25A and 25B are the same as the configurations shown in Figures 16A and 16B. The configuration shown in Figure 25C is the same as the configuration shown in Figure 22C. Other configurations and simulation conditions are the same as the configurations and simulation conditions described with reference to Figures 16A to 16C.

[0078] FIG. 26 shows the simulation results for the non-mounted edge, and FIG. 27 shows the simulation results for the mounted edge. The horizontal axis of the graphs shown in FIGS. 26 and 27 represents frequency, and the vertical axis represents the attenuation of the amplitude of the reflected wave in common logarithm. The smaller the amplitude of the reflected wave, the stronger the absorption of the radio wave. At a frequency of 47 GHz, as shown in FIG. 26 , it can be seen that the radio wave is strongly absorbed on the non-mounted edge when the radio wave absorbing pattern 174 has its basic shape. Also, as shown in FIG. 27 , it can be seen that the radio wave is strongly absorbed on the mounted edge when the radio wave absorbing pattern 174 has a shape that extends the edge that contributes to radio wave resonance. As in Example 1, it can be seen that using radio wave absorbing patterns with the same shape on the non-mounted edge and the mounted edge results in a change in the frequency at which the resonance peak occurs. Therefore, it is preferable to use radio wave absorbing patterns with different shapes on the non-mounted edge and the mounted edge. Furthermore, it is preferable that the radio wave absorbing patterns on the non-mounted edge and the mounted edge are not similar in shape, but rather have a shape in which only the edge that contributes to radio wave resonance is extended.

[0079] Table 4 shows the simulation conditions and the results of the reflection amplitudes at the non-mounted edge and the mounted edge. This suggests that strong radio wave absorption can be achieved by using the radio wave absorbing pattern as the basic shape at the non-mounted edge and by using a shape at the mounted edge that is longer than the basic shape only for the edges that contribute to radio wave resonance. Furthermore, comparing Fig. 22A with Fig. 25A, Fig. 25A shows that a conductive layer 176 is provided at the non-mounted edge. Comparing Fig. 24 with Fig. 27, it can be seen that stronger radio wave absorption is achieved by sandwiching the non-mounted edge of the opposing substrate 104 between the radio wave absorbing pattern 166 and the conductive layer 176.

[0080]

[0081] 5. Example 5 Figures 28A to 28C show a simulation model of a radio wave reflecting device in Example 5. Figure 28A is a cross-sectional view of the simulation model at the non-mounting edge, Figure 28B is a cross-sectional view of the simulation model at the mounting edge, and Figure 28C is a top view of the radio wave absorbing pattern. The configurations shown in Figures 28A and 28B are similar to the configurations shown in Figures 16A and 16B. The difference from the configuration shown in Figure 16C is that the shape of the radio wave absorbing pattern 174 shown in Figure 28C is composed of a circular conductive layer. The basic shape of the radio wave absorbing pattern 174 was such that the radius r of the circular conductive layer was 1.0 mm and the width W of the circular conductive layer was 0.40 mm. Furthermore, the length of the edge contributing to resonance was extended, and the radius r of the circular conductive layer was 1.4 mm and the width W of the circular conductive layer was 0.40 mm. In addition, as a figure similar to the basic shape, the radius r of the annular conductive layer was set to 1.4 mm, and the width W of the annular conductive layer was set to 0.56 mm. The other configurations and simulation conditions were the same as those described in Figures 16A to 16C.

[0082] FIG. 29 shows the simulation results for the non-mounted edge, and FIG. 30 shows the simulation results for the mounted edge. The horizontal axis of the graphs shown in FIGS. 29 and 30 represents frequency, and the vertical axis represents the attenuation of the amplitude of the reflected wave in common logarithm. The smaller the amplitude of the reflected wave, the stronger the absorption of the radio wave. At a frequency of 47 GHz, as shown in FIG. 29 , it can be seen that the radio wave absorbing pattern 174 on the non-mounted edge is strongly absorbed when it has its basic shape. Furthermore, as shown in FIG. 30 , it can be seen that the radio wave absorbing pattern 174 on the mounted edge is strongly absorbed when it has a shape that extends the edge that contributes to radio wave resonance. As in Example 1, it can be seen that using radio wave absorbing patterns with the same shape on the non-mounted edge and the mounted edge results in a change in the frequency at which the resonance peak occurs. Therefore, it is preferable to use radio wave absorbing patterns with different shapes on the non-mounted edge and the mounted edge. Furthermore, it is preferable that the radio wave absorbing patterns on the non-mounted edge and the mounted edge are not similar in shape, but are shaped such that only the edge that contributes to radio wave resonance is longer.

[0083]

[0084] Table 5 shows the simulation conditions and the results of the reflection amplitudes on the non-mounted sides and mounted sides. This suggests that it is possible to strongly absorb radio waves by using the radio wave absorbing pattern as the basic shape on the non-mounted sides, and by using a shape on the mounted sides where only the length of the side that contributes to radio wave resonance is longer than the basic shape.

[0085] The above-described embodiments of the present invention can be combined as appropriate as long as they are not mutually contradictory. Furthermore, based on the radio wave reflecting element or radio wave reflecting device of each embodiment, a person skilled in the art can add or delete components or change the design as appropriate, or add or omit processes or change conditions, and these will also be included in the scope of the present invention as long as they include the gist of the present invention.

[0086] Even if there are other effects and advantages different from those brought about by the aspects of each of the above-mentioned 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.

[0087] 100: radio wave reflecting device, 102: array substrate, 104: opposing substrate, 106: scanning line driving circuit, 108: signal line driving circuit, 110: terminal portion, 112: undercoat, 114: interlayer insulating film, 116: planarizing film, 118: interlayer insulating film, 120: transistor, 122: gate electrode, 124: gate insulating film, 126: semiconductor film, 128: electrode, 130: electrode, 132: overcoat, 134: wiring pattern, 140: radio wave reflecting element, 142: driving electrode, 144: first alignment film, 146: liquid crystal layer, 148: second alignment film, 150: common electrode, 152: sealing material, 153: adhesive material, 154: conductive layer, 155: conductive layer, 156: transparent conductive layer, 157: anisotropic conductive layer, 158: flexible printed circuit board, 160: cover member, 166: radio wave absorbing pattern, 166-1: rectangular conductive layer, 166-2: rectangular conductive layer, 168: radio wave absorbing pattern, 170: metasurface reflector, 172: conductor pattern, 174: radio wave absorbing pattern, 174-1: rectangular conductive layer, 174-2: rectangular conductive layer, 176: conductive layer

Claims

1. A radio wave reflecting device comprising: a metasurface reflector having a radio wave reflecting area in which a plurality of radio wave reflecting elements are arranged, and a frame area surrounding the radio wave reflecting area; and a cover member arranged on the radio wave incident surface side of the metasurface reflector, wherein the frame area includes a first area in which a wiring pattern is formed, and a second area in which a terminal portion for connecting to an external circuit is provided, and the cover member includes a first radio wave absorbing pattern provided in an area overlapping with the first area, and a second radio wave absorbing pattern provided in an area overlapping with the second area, and the size of the second radio wave absorbing pattern is larger than the size of the first radio wave absorbing pattern.

2. The radio wave reflection device described in claim 1, wherein the metasurface reflector includes an array substrate on which a drive electrode is provided, an opposing substrate facing the array substrate and on which a common electrode is provided, and a liquid crystal layer between the array substrate and the opposing substrate, the array substrate having the terminal portion provided thereon, and the terminal portion being exposed from the opposing substrate.

3. A radio wave reflecting device as described in claim 1, wherein the length of the side that contributes to the resonance of radio waves in the shape of the second radio wave absorbing pattern is longer than the length of the side that contributes to the resonance of radio waves in the shape of the first radio wave absorbing pattern.

4. The radio wave reflecting device according to claim 2, wherein the first radio wave absorbing pattern is provided between the opposing substrate and the cover member, and the second radio wave absorbing pattern is provided on the underside of the cover member.

5. The radio wave reflecting device according to claim 2, wherein the first radio wave absorbing pattern is provided between the opposing substrate and the cover member, and the second radio wave absorbing pattern is provided on the upper surface of the cover member.

6. A radio wave reflecting device according to claim 2, wherein the first radio wave absorbing pattern is provided on the upper surface of the cover member, and the second radio wave absorbing pattern is provided on the lower surface of the cover member.

7. The radio wave reflecting device according to claim 2, wherein the first radio wave absorbing pattern and the second radio wave absorbing pattern are provided on the upper surface of the cover member.

8. The radio wave reflecting device according to claim 1, further comprising a sealing material arranged in the frame area so as to surround the radio wave reflecting area, and the first radio wave absorbing pattern is arranged so as to overlap with the sealing material.

9. A radio wave reflecting device comprising: a metasurface reflector having a radio wave reflecting area in which a plurality of radio wave reflecting elements are arranged, and a frame area surrounding the radio wave reflecting area; and a cover member arranged on the radio wave incident surface side of the metasurface reflector, wherein the frame area includes a first area in which a wiring pattern is formed, and a second area in which a terminal portion for connecting to an external circuit is provided, and the cover member includes: a first radio wave absorbing pattern provided in an area overlapping with the first area, and a second radio wave absorbing pattern provided in an area overlapping with the second area, and a conductor pattern is provided in the first area between the wiring pattern and the first radio wave absorbing pattern, and the size of the second radio wave absorbing pattern is larger than the size of the first radio wave absorbing pattern.

10. The radio wave reflection device described in claim 9, wherein the metasurface reflector includes an array substrate on which a drive electrode is provided, an opposing substrate facing the array substrate and on which a common electrode is provided, and a liquid crystal layer between the array substrate and the opposing substrate, the array substrate having the terminal portion provided thereon, and the terminal portion being exposed from the opposing substrate.

11. The radio wave reflecting device according to claim 10, wherein the conductive pattern is provided on the opposing substrate so as to surround the common electrode, and the conductive pattern faces the first radio wave absorbing pattern via the opposing substrate.

12. A radio wave reflecting device according to claim 9, wherein the length of the side that contributes to resonance in the shape of the second radio wave absorbing pattern is longer than the length of the side that contributes to resonance in the shape of the first radio wave absorbing pattern.

13. A radio wave reflecting device according to claim 10, wherein the first radio wave absorbing pattern is provided between the opposing substrate and the cover member, and the second radio wave absorbing pattern is provided on the underside of the cover member.

14. The radio wave reflecting device according to claim 10, wherein the first radio wave absorbing pattern is provided between the opposing substrate and the cover member, and the second radio wave absorbing pattern is provided on the upper surface of the cover member.

15. A radio wave reflecting device according to claim 10, wherein the first radio wave absorbing pattern is provided on the upper surface of the cover member, and the second radio wave absorbing pattern is provided on the lower surface of the cover member.

16. The radio wave reflecting device according to claim 10, wherein the first radio wave absorbing pattern and the second radio wave absorbing pattern are provided on the upper surface of the cover member.

17. The radio wave reflection device according to claim 9, further comprising a sealing material arranged in the frame area so as to surround the radio wave reflection area, and the first radio wave absorption pattern and the conductor pattern are arranged so as to overlap with the sealing material.

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