Radio wave reflection device
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- JAPAN DISPLAY INC
- Filing Date
- 2022-11-09
- Publication Date
- 2026-08-03
Smart Images
Figure 0007899057000001 
Figure 0007899057000002 
Figure 0007899057000003
Abstract
Description
Technical Field
[0001] The present invention relates to a radio wave reflection device.
Background Art
[0002] A phased array antenna device controls the directivity of an antenna in a fixed state by adjusting the amplitude and phase of a high-frequency signal applied to each of a plurality of antenna elements arranged in a planar shape. A phased array antenna device requires a phase shifter. A phased array antenna device using a phase shifter utilizing the change in dielectric constant due to the alignment state of liquid crystal has been disclosed (see, for example, Patent Document 1 and Patent Document 2).
Prior Art Documents
Patent Documents
[0003]
Patent Document 1
Patent Document 2
Summary of the Invention
Problems to be Solved by the Invention
[0004] A radio wave reflection device using a radio wave reflector that can control the reflection direction using liquid crystal, such as a phased array antenna device, can control the reflection direction in any direction depending on the voltage applied to the liquid crystal. In the spread of the fifth-generation mobile communication system (5G), it is necessary to further expand the amount of phase change of the reflection phase. However, in expanding the amount of phase change of the reflection phase, there is a problem that it is difficult to control the voltage applied to the liquid crystal and a desired reflection intensity cannot be obtained.
[0005] In view of such problems, one object of an embodiment of the present invention is to provide a radio wave reflection device having a large amount of phase change of radio waves and a high reflection intensity.
Means for Solving the Problems
[0006] A radio wave reflector according to one embodiment of the present invention includes a first patch electrode, a second patch electrode adjacent to the first patch electrode, a third patch electrode adjacent to the first patch electrode, a fourth patch electrode adjacent to the second patch electrode and the third patch electrode, a common electrode facing the first patch electrode and the second patch electrode, a liquid crystal layer between the first patch electrode, the second patch electrode and the common electrode, and a first wiring between the first patch electrode and the second patch electrode, wherein the area of the first patch electrode is different in size from the areas of the second and third patch electrodes, and the distance between the first patch electrode and the first wiring is equal to the distance between the second patch electrode and the first wiring. [Brief explanation of the drawing]
[0007] [Figure 1A] A plan view of a reflective element used in a radio wave reflector according to one embodiment of the present invention is shown. [Figure 1B] This shows a cross-sectional view of a reflective element used in a radio wave reflector according to one embodiment of the present invention. [Figure 2A] This shows the state when a reflective element used in a radio wave reflector according to one embodiment of the present invention is in operation, and shows a state in which no voltage is applied between the patch electrode and the common electrode. [Figure 2B] This shows the state when a reflective element used in a radio wave reflector according to one embodiment of the present invention is in operation, and shows the state in which a voltage is applied between the patch electrode and the common electrode. [Figure 3] This diagram schematically illustrates how the direction of propagation of reflected waves changes due to a radio wave reflector according to one embodiment of the present invention. [Figure 4] The configuration of a radio wave reflector according to one embodiment of the present invention is shown. [Figure 5] A plan view of a reflective element used in a radio wave reflector according to one embodiment of the present invention is shown. [Figure 6] This shows a cross-sectional view of a reflective element in a radio wave reflector according to one embodiment of the present invention. [Figure 7]This shows a cross-sectional view of wiring used in a radio wave reflector according to one embodiment of the present invention. [Figure 8] The configuration of a radio wave reflector according to one embodiment of the present invention is shown. [Figure 9] A plan view of a reflective element used in a radio wave reflector according to one embodiment of the present invention is shown. [Modes for carrying out the invention]
[0008] [Background leading to the invention] The inventors of the present invention have been developing a method to increase the amount of phase change in the reflection phase of a reflective element by applying a voltage of the same potential to the liquid crystal of the reflective element and using patch electrodes of different sizes. During this development, it was found that a decrease in reflection intensity sometimes occurs due to the provision of power supply wiring between these patch electrodes. The embodiment of the present invention improves this decrease in reflection intensity.
[0009] Embodiments of the present invention will be described below with reference to the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described below. In order to make the explanation clearer, the drawings may schematically represent the width, thickness, shape, etc. of each part compared to the actual embodiment, but these are merely examples and do not limit the interpretation of the present invention. In addition, in this specification and each drawing, elements similar to those described above with respect to previously shown drawings are denoted by the same reference numerals (or numerals followed by a, b, etc.), and detailed explanations may be omitted as appropriate. Furthermore, the letters "1st" and "2nd" appended to each element are convenient indicators used to distinguish each element and have no further meaning unless specifically explained.
[0010] In this specification, when a member or region is said to be "above (or below)" another member or region, unless otherwise specified, this includes not only cases where it is directly above (or directly below) the other member or region, but also cases where it is above (or below) the other member or region, that is, cases where another component is included between them above (or below) the other member or region.
[0011] In this specification, when the area of one member or region is considered "equal" to the area of another member or region, the difference between their areas is within 10%, preferably within 5%, and more preferably within 3% of the area of one. Also, when the spacing between one member and another is considered "equal," the difference between their distances is within 10%, preferably within 5%, and more preferably within 3% of the distance of one. Furthermore, when the lengths of one member and another are considered "equal," the difference between their lengths is within 10%, preferably within 5%, and more preferably within 3% of the length of one.
[0012] [Overall structure] Figures 1A and 1B show a reflective element 102 used in a radio wave reflector according to one embodiment of the present invention. <Reflective element> Figure 1A shows a plan view of the reflecting element 102 as seen from above (the side from which the radio waves are incident), and Figure 1B shows a cross-sectional view of the section between A1 and A2 shown in the plan view.
[0013] As shown in FIGS. 1A and 1B, the reflective element 102 includes a dielectric substrate 104, a counter substrate 106, a patch electrode 108, a common electrode 110, a first alignment film 112a, a second alignment film 112b, and a liquid crystal layer 114. The dielectric substrate 104 in the reflective element 102 can also be regarded as a dielectric layer forming a single layer. The patch electrode 108 is provided on the dielectric substrate (dielectric layer) 104, and the common electrode 110 is provided on the counter substrate 106. The common electrode 110 is disposed on the back side of the patch electrode 108. A first alignment film 112a is provided on the dielectric substrate (dielectric layer) 104 so as to cover the patch electrode 108, and a second alignment film 112b is provided on the counter substrate 106 so as to cover the common electrode 110. The patch electrode 108 and the common electrode 110 are arranged to face each other, and a liquid crystal layer 114 is provided therebetween. The first alignment film 112a is interposed between the patch electrode 108 and the liquid crystal layer 114, and the second alignment film 112b is interposed between the common electrode 110 and the liquid crystal layer 114.
[0014] The patch electrode 108 preferably has a shape that is symmetric with respect to the vertical polarization and horizontal polarization of the incident radio wave, and has a square or rectangular shape in plan view. When a plurality of patch electrodes 108 are arranged, adjacent patch electrodes 108 differ from each other in area, shape, or arrangement direction. FIG. 1A shows the case where the patch electrode 108 is square in plan view. The shape of the common electrode 110 is not particularly limited, and has a shape that spreads over substantially the entire surface of the counter substrate 106 so as to have a larger area than the patch electrode 108. There is no limitation on the material for forming the patch electrode 108 and the common electrode 110, and they are formed using a conductive metal or metal oxide. A connection wiring 109 may be provided on the dielectric substrate (dielectric layer) 104. The connection wiring 109 is connected to the patch electrode 108 and can be used when applying a control signal to the patch electrode 108.
[0015] Although not shown in FIGS. 1A and 1B, the dielectric substrate (dielectric layer) 104 and the counter substrate 106 are bonded together by a sealing material. The dielectric substrate (dielectric layer) 104 and the counter substrate 106 are arranged to face each other with a gap therebetween, and the liquid crystal layer 114 is provided within the region surrounded by the sealing material. The liquid crystal layer 114 is provided so as to fill the gap between the dielectric substrate (dielectric layer) 104 and the counter substrate 106. The distance between the dielectric substrate (dielectric layer) 104 and the counter substrate 106 is 20 to 100 μm, for example, having a distance of 50 μm. Since the patch electrode 108, the common electrode 110, the first alignment film 112a, and the second alignment film 112b are provided between the dielectric substrate (dielectric layer) 104 and the counter substrate 106, precisely, the distance between the first alignment film 112a and the second alignment film 112b provided on each of the dielectric substrate 104 and the counter substrate 106 becomes the thickness of the liquid crystal layer 114. Although not shown in FIG. 1B, a spacer for maintaining a constant distance may be provided between the dielectric substrate (dielectric layer) 104 and the counter substrate 106.
[0016] A control signal for controlling the alignment of the liquid crystal molecules in the liquid crystal layer 114 is applied to the patch electrode 108. The control signal is a signal of a DC voltage or a polarity inversion signal in which a positive DC voltage and a negative DC voltage alternately invert. The common electrode 110 is grounded or a voltage at an intermediate level of the polarity inversion signal is applied. By applying the control signal to the patch electrode 108, the alignment state of the liquid crystal molecules contained in the liquid crystal layer 114 changes. A liquid crystal material having dielectric anisotropy is used for the liquid crystal layer 114. For example, a nematic liquid crystal, a smectic liquid crystal, a cholesteric liquid crystal, or a discotic liquid crystal can be used as the liquid crystal layer 114. The liquid crystal layer 114 having dielectric anisotropy changes its dielectric constant due to the change in the alignment state of the liquid crystal molecules. The reflection element 102 can change the dielectric constant of the liquid crystal layer 114 by the control signal applied to the patch electrode 108, and thereby can delay the phase of the reflected wave when reflecting radio waves.
[0017] The frequency bands of radio waves reflected by the reflecting element 102 are the very high frequency (VHF), ultra-high frequency (UHF), super high frequency (SHF), submillimeter wave (THF), and extra high frequency (EHF) bands. The liquid crystal molecules in the liquid crystal layer 114 change their orientation in response to the control signal applied to the patch electrode 108, but they hardly follow the frequency of the radio waves irradiated onto the patch electrode 108. Therefore, the reflecting element 102 can control the phase of the reflected radio waves without being affected by the radio waves.
[0018] Figure 2A shows the state in which no voltage is applied between the patch electrode 108 and the common electrode 110 (referred to as the "first state"). Figure 2A shows the case where the first alignment film 112a and the second alignment film 112b are horizontal alignment films. In the first state, the long axis of the liquid crystal molecules 116 is oriented horizontally with respect to the surfaces of the patch electrode 108 and the common electrode 110 by the first alignment film 112a and the second alignment film 112b. Figure 2B shows the state in which a control signal (voltage signal) is applied to the patch electrode 108 (referred to as the "second state"). In the second state, the liquid crystal molecules 116 are affected by the electric field and their long axes are oriented perpendicular to the surfaces of the patch electrode 108 and the common electrode 110. The angle at which the long axis of the liquid crystal molecules 116 is oriented can also be adjusted to an intermediate direction between the horizontal and vertical directions, depending on the magnitude of the control signal applied to the patch electrode 108 (the magnitude of the voltage between the opposing electrode and the patch electrode).
[0019] When the liquid crystal molecules 116 have positive dielectric anisotropy, the dielectric constant is higher in the second state than in the first state. Conversely, when the liquid crystal molecules 116 have negative dielectric anisotropy, the apparent dielectric constant is lower in the second state than in the first state. The liquid crystal layer 114 with dielectric anisotropy can also be considered a variable dielectric layer. The reflecting element 102 can control the phase of the reflected wave by delaying (or not delaying) it by utilizing the dielectric anisotropy of the liquid crystal layer 114.
[0020] The reflective element 102 is used in a radio wave reflector that reflects radio waves in a predetermined direction. It is preferable that the amplitude of the reflected radio waves is not attenuated as much as possible by the reflective element 102. As is clear from the structure shown in Figure 1B, when radio waves propagating in the air are reflected by the reflective element 102, the radio waves pass through the dielectric substrate (dielectric layer) 104 twice. The dielectric substrate (dielectric layer) 104 is formed of a dielectric material such as glass or resin.
[0021] A radio wave reflector can change the direction of reflected waves by using multiple reflective elements.
[0022] Figure 3 schematically illustrates how the direction of propagation of a reflected wave changes when two reflecting elements 102 are used. It shows the case where, when radio waves are incident on the first reflecting element 102a and the second reflecting element 102b with the same phase, different control signals (V1≠V2) are applied to the first reflecting element 102a and the second reflecting element 102b, resulting in a larger phase change of the reflected wave by the second reflecting element 102b compared to the first reflecting element 102a. As a result, the phase of the reflected wave R1 reflected by the first reflecting element 102a is different from the phase of the reflected wave R2 reflected by the second reflecting element 102b (in Figure 3, the phase of reflected wave R2 is ahead of the phase of reflected wave R1), and the direction of propagation of the reflected wave appears to change diagonally.
[0023] <Radio wave reflection device> Next, the configuration of a radio wave reflector with integrated reflecting elements is shown.
[0024] Figure 4 shows the configuration of a radio wave reflector 100 according to one embodiment of the present invention. The radio wave reflector 100 has a radio wave reflector 120, which is composed of a plurality of reflecting elements 102. The plurality of reflecting elements 102 are arranged, for example, in the column direction (X-axis direction shown in Figure 4) and in the row direction (Y-axis direction shown in Figure 4) intersecting the column direction. The reflecting elements 102 are arranged such that the patch electrodes 108 face the incident surface of the radio waves. The radio wave reflector 120 is flat, and four patch electrodes 108 are arranged as a first pattern 119 within the surface of this flat plate, and the first pattern 119 is arranged periodically in the column direction and the row direction.
[0025] The radio wave reflector 100 has a structure in which multiple reflecting elements 102 are integrated on a single dielectric substrate (dielectric layer) 104. As shown in Figure 4, the radio wave reflector 100 has a structure in which a dielectric substrate (dielectric layer) 104 on which multiple patch electrodes 108 are arranged and a counter substrate 106 on which a common electrode 110 is provided are stacked on top of each other, with a liquid crystal layer (not shown) provided between the two substrates. The radio wave reflector 120 is formed in the region where the multiple patch electrodes 108 and the common electrode 110 overlap. The cross-sectional structure of the radio wave reflector 120 is the same as the structure of the reflecting element 102 shown in Figure 1B when viewed for each patch electrode 108. The dielectric substrate (dielectric layer) 104 and the counter substrate 106 are bonded together with a sealing material 128, and the liquid crystal layer (not shown) is provided in the region inside the sealing material 128.
[0026] The dielectric substrate (dielectric layer) 104 has a region facing the opposing substrate 106, as well as a peripheral region 122 that extends outward from the opposing substrate 106. The peripheral region 122 is provided with a first drive circuit 124, a second drive circuit 130, and a terminal section 126. The first drive circuit 124 outputs a control signal to the patch electrode 108. The second drive circuit 130 outputs a scanning signal. The terminal section 126 is a region that forms a connection with an external circuit, and for example, a flexible printed circuit board (not shown) is connected to it. A signal to control the first drive circuit 124 is input to the terminal section 126.
[0027] As described above, multiple patch electrodes 108 are arranged on the dielectric substrate (dielectric layer) 104 in a first direction (X-axis direction) and a second direction (Y-axis direction). The arranged multiple patch electrodes 108 differ in size from adjacent patch electrodes 108; specifically, even if adjacent patch electrodes 108 have the same shape, their areas differ. For example, as shown in Figure 4, the multiple patch electrodes 108 are square in shape. In the multiple patch electrodes 108, one adjacent patch electrode 108 in the first and second directions has a larger area, while the other adjacent patch electrode 108 has a smaller area. Furthermore, in the multiple patch electrodes 108, another patch electrode 108 located diagonally opposite to one patch electrode 108 is the same size.
[0028] Furthermore, multiple first wirings 118 extending in a second direction (Y-axis direction) are arranged on the dielectric substrate (dielectric layer) 104. Each of the multiple first wirings 118 is electrically connected to a row of patch electrodes 108 arranged in the second direction (Y-axis direction). The radio wave reflector 120 has a configuration in which multiple rows of patch electrode arrays electrically connected by the first wirings 118 are arranged in the first direction (X-axis direction).
[0029] Multiple first wires 118 arranged on the radio wave reflector 120 extend into the surrounding area 122 and are connected to the first drive circuit 124. The first drive circuit 124 is capable of outputting control signals of different voltage levels to each of the multiple first wires 118. As a result, on the radio wave reflector 120, control signals are applied to each row (each patch electrode 108 arranged in the second direction (Y-axis direction)) of the multiple patch electrodes 108 arranged in the first direction (X-axis direction) and the second direction (Y-axis direction).
[0030] Multiple first wires 118 extending to the first drive circuit 124 are arranged at equidistant distances between adjacent patch electrodes 108. The multiple first wires 118 are positioned such that adjacent patch electrodes 108 are symmetrical with respect to the first wire 118. Because the areas of adjacent patch electrodes 108 are different, the multiple first wires 118 extend to the first drive circuit 124 while bending between the multiple patch electrodes 108. Therefore, the first wires 118 have multiple bends between the multiple patch electrodes 108 in the radio wave reflector 120.
[0031] The radio wave reflector 100 further has a plurality of second wirings 132 extending in a first direction (X-axis direction). The plurality of first wirings 118 and the plurality of second wirings 132 are arranged to intersect with an insulating layer, which will be described later, in between. The plurality of second wirings 132 are connected to a second drive circuit 130. The second drive circuit 130 outputs a scanning signal.
[0032] Multiple second wires 132 extending to the second drive circuit 130 maintain equal distances between multiple patch electrodes 108. The multiple second wires 132 are positioned such that adjacent patch electrodes 108 are symmetrical with respect to the second wire 132. Because the areas of adjacent patch electrodes 108 differ, the multiple second wires 132 bend between the patch electrodes 108 as they extend to the second drive circuit 130. Therefore, the second wires 132 have multiple bends by the time they reach the second drive circuit 130.
[0033] Each of the multiple patch electrodes 108 is provided with a switching element 134, which will be described later. The switching (on and off) of the switching element 134 is controlled by a scanning signal applied to the second wiring 132. When the switching element 134 is turned on, the patch electrode 108 becomes conductive with the first wiring 118 and a control signal is applied. The switching element 134 is formed, for example, from a thin-film transistor. With this configuration, multiple patch electrodes 108 arranged in the first direction (X-axis direction) can be selected row by row, and control signals with different voltage levels can be applied to each row.
[0034] The radio wave reflector 100 can control the propagation direction of reflected waves in the left-right direction of the drawing, centered on a reflection axis VR parallel to the row direction (Y-axis direction), and can also control the propagation direction of reflected waves in the up-down direction of the drawing, centered on a reflection axis HR parallel to the first direction (X-axis direction). In other words, because the radio wave reflector 100 has a reflection axis VR parallel to the row direction (Y-axis direction) and a reflection axis HR parallel to the first direction (X-axis direction), it can control the reflection angle in the direction around the reflection axis VR as the axis of rotation and in the direction around the reflection axis HR as the axis of rotation.
[0035] By applying this principle to the radio wave reflector 100, for example, by independently controlling the amount of phase change by the reflecting elements in both the first and second direction arrangements, the reflection direction can be controlled in both uniaxial and biaxial directions.
[0036] Figure 5 shows a plan view of the reflective element 102 shown in Figure 4. The first region 135 shown in Figure 5 is an enlarged view of the first region 135 shown in Figure 4.
[0037] The first region 135 includes a plurality of patch electrodes 108 positioned between a plurality of first wirings 118 and a plurality of second wirings 132, and a plurality of switching elements 134 connected to each of the patch electrodes 108.
[0038] First, the switching element 134 will be described with reference to Figure 6.
[0039] Figure 6 shows a cross-sectional view of the reflecting element 102. Figure 6 shows an example of the cross-sectional structure of the reflecting element 102 in which a switching element 134 is connected to a patch electrode 108. The switching element 134 is provided on a dielectric substrate (dielectric layer) 104. The switching element 134 is a transistor and has a structure in which a first gate electrode 138, a first gate insulating layer 140, a semiconductor layer 142, a second gate insulating layer 146, and a second gate electrode 148 are stacked. An undercoat layer 136 may be provided between the first gate electrode 138 and the dielectric substrate (dielectric layer) 104. A first wiring 118 is provided between the first gate insulating layer 140 and the second gate insulating layer 146. The first wiring 118 is provided so as to be in contact with the semiconductor layer 142. In addition, a first connecting wiring 144 is provided in the same layer as the conductive layer forming the first wiring 118. The first connecting wiring 144 is provided so as to be in contact with the semiconductor layer 142. The connection structure of the first wiring 118 and the first connecting wiring 144 to the semiconductor layer 142 is such that one wiring is connected to the source of the transistor and the other wiring is connected to the drain. The wiring may also be electrically connected to the source or drain of the transistor via conductive connecting wiring or electrode pads.
[0040] A first interlayer insulating layer 150 is provided so as to cover the switching element 134. A second wiring 132 is provided on the first interlayer insulating layer 150. The second wiring 132 is connected to the second gate electrode 148 via a contact hole formed in the first interlayer insulating layer 150. Although not shown, the first gate electrode 138 and the second gate electrode 148 are electrically connected to each other in a region that does not overlap with the semiconductor layer 142. A second connecting wiring 152 is provided on the first interlayer insulating layer 150, using the same conductive layer as the second wiring 132. The second connecting wiring 152 is connected to the first connecting wiring 144 via a contact hole formed in the first interlayer insulating layer 150.
[0041] A second interlayer insulating layer 154 is provided so as to cover the second wiring 132 and the second connecting wiring 152. Furthermore, a planar layer 156 is provided so as to fill the step in the switching element 134. By providing the planar layer 156, the patch electrode 108 can be formed without being affected by the arrangement of the switching element 134. A passivation layer 158 is provided on the flat surface of the planar layer 156. The patch electrode 108 is provided on the passivation layer 158. The patch electrode 108 is connected to the second connecting wiring 152 via contact holes that penetrate the passivation layer 158, the planar layer 156, and the second interlayer insulating layer 154. A first orientation film 112a is provided on the patch electrode 108.
[0042] The opposing substrate 106 is provided with a common electrode 110 and a second alignment film 112b, similar to Figure 1B. The surfaces of the dielectric substrate (dielectric layer) 104 on which the switching element 134 and patch electrode 108 are provided are positioned opposite the surface of the opposing substrate 106 on which the common electrode 110 is provided, with the liquid crystal layer 114 provided between them. The thickness T of the dielectric substrate (dielectric layer) 104 can be the length from the surface of the patch electrode 108 on the liquid crystal layer 114 side to the surface of the dielectric substrate (dielectric layer) 104 opposite to the surface on which the patch electrode 108 is provided. In this case, the thickness of at least one insulating layer (undercoat layer 136, first gate insulating layer 140, second gate insulating layer 146, first interlayer insulating layer 150, second interlayer insulating layer 154, planarization layer 156, passivation layer 158) between the patch electrode 108 and the dielectric substrate (dielectric layer) 104 can be taken into consideration.
[0043] Each layer formed on the dielectric substrate (dielectric layer) 104 is formed using the following materials. The undercoat layer 136 is formed of, for example, a silicon oxide film. The first gate insulating layer 140 and the second gate insulating layer 146 are formed of, for example, a silicon oxide film, or a laminated structure of a silicon oxide film and a silicon nitride film. The semiconductor layer is formed of an oxide semiconductor containing silicon semiconductors such as amorphous silicon and polycrystalline silicon, or metal oxides such as indium oxide, zinc oxide, and gallium oxide. The first gate electrode 138 and the second gate electrode 148 may be composed of, for example, molybdenum (Mo), tungsten (W), or alloys thereof. The first wiring 118, the second wiring 132, the first connecting wiring 144, and the second connecting wiring 152 are formed using metallic materials such as titanium (Ti), aluminum (Al), and molybdenum (Mo). For example, they may be composed of a titanium (Ti) / aluminum (Al) / titanium (Ti) laminated structure, or a molybdenum (Mo) / aluminum (Al) / molybdenum (Mo) laminated structure. The planarization layer 156 is formed from a resin material such as acrylic or polyimide. The passivation layer 158 is formed from, for example, a silicon nitride film. The patch electrode 108 and common electrode 110 are formed from a metal film such as aluminum (Al) or copper (Cu), or a transparent conductive film such as indium tin oxide (ITO).
[0044] As shown in Figure 6, by connecting the second wiring 132 to the gate of a transistor used as a switching element 134, connecting the first wiring 118 to one of the source and drain of the transistor, and connecting the patch electrode 108 to the other of the source and drain, a control signal can be applied to a predetermined patch electrode 108 from among a plurality of patch electrodes 108 arranged in the first and second directions. By providing a switching element 134 to each patch electrode 108 in the radio wave reflector 120, a control voltage can be applied to each patch electrode 108 arranged in a horizontal row along the first direction (X-axis direction) or to each patch electrode 108 arranged in a vertical row along the second direction (Y-axis direction). For example, when the radio wave reflector 120 is upright, the reflection direction of the reflected wave can be controlled in the left-right and up-down directions.
[0045] Next, we will describe the multiple patch electrodes 108 connected to the multiple switching elements 134.
[0046] The first region 135 shown in Figure 5 represents a first pattern 119 that is repeatedly arranged in the first and second directions. The first pattern 119 is where the first patch electrode 108-1, the second patch electrode 108-2, the third patch electrode 108-3, and the fourth patch electrode 108-4 are arranged.
[0047] The first patch electrode 108-1 and the second patch electrode 108-2 are arranged alternately in the first direction, as shown in Figure 5. The third patch electrode 108-3 and the fourth patch electrode 108-4 are also arranged alternately in the first direction, as shown in Figure 5. Furthermore, the first patch electrode 108-1 and the third patch electrode 108-3, and the second patch electrode 108-2 and the fourth patch electrode 108-4 are arranged alternately in the second direction, as shown in Figure 5. Therefore, for example, the second patch electrode 108-2 is positioned so as to be sandwiched between the two first patch electrodes 108-1 in the first direction, and so as to be sandwiched between the two fourth patch electrodes 108-4 in the second direction.
[0048] The first patch electrode 108-1 is adjacent to the second patch electrode 108-2, and its area is different from that of the second patch electrode 108-2. The area of the first patch electrode 108-1 is larger than that of the second patch electrode 108-2. Furthermore, the first patch electrode 108-1 is adjacent to the third patch electrode 108-3, and its area is different from that of the third patch electrode 108-3. The area of the first patch electrode 108-1 is larger than that of the third patch electrode 108-3.
[0049] The second patch electrode 108-2 is located diagonally opposite the third patch electrode 108-3, and the area of the second patch electrode 108-2 is equal to the area of the third patch electrode 108-3. Furthermore, the second patch electrode 108-2 is adjacent to the fourth patch electrode 108-4, and the area of the second patch electrode 108-2 is smaller than the area of the fourth patch electrode 108-4.
[0050] The third patch electrode 108-3 is adjacent to the fourth patch electrode 108-4, and the area of the third patch electrode 108-3 is smaller than the area of the fourth patch electrode 108-4.
[0051] The fourth patch electrode 108-4 is located diagonally opposite the first patch electrode 108-1, and the area of the fourth patch electrode 108-4 is equal to the area of the first patch electrode 108-1.
[0052] Either the first wiring 118 or the second wiring 132 is placed between the first patch electrode 108-1, the second patch electrode 108-2, the third patch electrode 108-3, and the fourth patch electrode 108-4, respectively. Specifically, the first wiring 118 is placed between the first patch electrode 108-1 and the second patch electrode 108-2, and between the third patch electrode 108-3 and the fourth patch electrode 108-4. Furthermore, the second wiring 132 is placed between the first patch electrode 108-1 and the third patch electrode 108-3, and between the second patch electrode 108-2 and the fourth patch electrode 108-4. In addition, the second wiring 132 is placed between the first patch electrode 108-1 and the fourth patch electrode 108-4, and the first wiring 118 is placed between the second patch electrode 108-2 and the third patch electrode 108-3.
[0053] The first wiring 118 is positioned equidistant from the first patch electrode 108-1 and the second patch electrode 108-2. Therefore, the distance a1 between the first wiring 118 and the first patch electrode 108-1 is equal to the distance a2 between the first wiring 118 and the second patch electrode 108-2. Furthermore, the first wiring 118 is positioned equidistant from the second patch electrode 108-2 and the third patch electrode 108-3. Therefore, the distance a2 between the first wiring 118 and the second patch electrode 108-2 is equal to the distance a3 between the first wiring 118 and the third patch electrode 108-3.
[0054] Furthermore, the distance between the first patch electrode 108-1 and the second patch electrode 108-2 is equal to the distance between the third patch electrode 108-3 and the fourth patch electrode 108-4. Therefore, distances a1 and a2 are equal to distances a3 and a4. The first wiring 118 is arranged at equal intervals between its patch electrodes and has a first bend 160 between the first patch electrode 108-1 and the fourth patch electrode 108-4 and between the second patch electrode 108-2 and the third patch electrode 108-3. The first wiring 118 has a first bend 160 between, for example, the nth (n is a natural number greater than or equal to 1) second wiring 132 that intersects with the first wiring 118 and the (n+1)th second wiring 132.
[0055] Furthermore, since the first wiring 118 is also arranged at equal intervals with adjacent patch electrodes in the first bend 160, as shown in Figure 5, the distance c1 between the first patch electrode 108-1 and the first bend 160 is equal to the distance c4 between the fourth patch electrode 108-4 and the first bend 160.
[0056] The second wiring 132 is positioned equidistant from the first patch electrode 108-1 and the third patch electrode 108-3. Therefore, the distance b1 between the second wiring 132 and the first patch electrode 108-1 is equal to the distance b3 between the second wiring 132 and the third patch electrode 108-3. Furthermore, the second wiring 132 is positioned equidistant from the second patch electrode 108-2 and the fourth patch electrode 108-4. Therefore, the distance b2 between the second wiring 132 and the second patch electrode 108-2 is equal to the distance b4 between the second wiring 132 and the fourth patch electrode 108-4.
[0057] Furthermore, the distance between the first patch electrode 108-1 and the third patch electrode 108-3 is equal to the distance between the second patch electrode 108-2 and the fourth patch electrode 108-4. Therefore, distances b1 and b3 are equal to distances b2 and b4. Since the second wiring 132 is arranged at equal intervals between these patch electrodes, it has a second bend 162 between the distance between the first patch electrode 108-1 and the third patch electrode and between the distance between the second patch electrode 108-2 and the fourth patch electrode 108-4.
[0058] The first bent portion 160 and the second bent portion 162 described above are parts of the first wiring 118 and the second wiring 132, respectively. Therefore, there is an insulating layer between the first bent portion 160 and the second bent portion 162. Now, referring to the cross-sectional view between B1 and B2 shown in Figure 5, the insulating layer between the first bent portion 160 and the second bent portion 162 will be explained.
[0059] Figure 7 shows a cross-sectional view of the wiring of the radio wave reflector 100. Figure 7 is a cross-sectional view of the first wiring 118 and wiring 132 between B1 and B2 shown in Figure 5.
[0060] Figure 7 shows an example of the cross-sectional structure of the first bent portion 160 and the second bent portion 162. In cross-sectional view, the first bent portion 160 overlaps with the second bent portion 162. Since the first bent portion 160 is part of the first wiring 118, it has an insulating layer between it and the second bent portion, which is part of the second wiring 132, for example, a second gate insulating layer 146. The first bent portion 160 may also have a first interlayer insulating layer 150 between it and the second bent portion 162.
[0061] As described above, the radio wave reflector 100 according to one embodiment of the present invention has adjacent patch electrodes 108 of different sizes, and the wiring for supplying power to the patch electrodes 108, which extends between these patch electrodes 108, is arranged at equal intervals with respect to the patch electrodes 108. By arranging the wiring in this way, the influence of radio waves from each wiring to the patch electrodes 108 can be suppressed, and a drop in the reflection amplitude at a certain frequency of the reflecting element 102, which expands the variable range in which radio waves are reflected by the patch electrodes 108 of different sizes, can be avoided. By avoiding a drop in reflection amplitude, the radio wave reflector 100 can increase the amount of phase change of radio waves and further improve the reflection intensity.
[0062] <Variation> A modified version of the radio wave reflector 200 will be described with reference to Figures 8 and 9. The difference from the radio wave reflector 100 shown in Figures 1 to 7 is that four patch electrodes 208 of different sizes or orientations are repeatedly arranged on the radio wave reflector 220. Furthermore, the difference from the radio wave reflector 100 shown in Figures 1 to 7 is that the first wiring 218 and the second wiring 232 do not have bends between the multiple patch electrodes 208. Note that explanations of configurations that are the same as or similar to the radio wave reflector 100 shown in Figures 1 to 7 may be omitted.
[0063] Figure 8 shows the configuration of the radio wave reflector 200. Figure 8 is a plan view of the radio wave reflector 200. Multiple patch electrodes 208 arranged on the dielectric substrate (dielectric layer) 204 are square or rectangular in shape. Adjacent patch electrodes 208 in the first and second directions have different shapes and areas from each other.
[0064] The first wiring 218, positioned between multiple patch electrodes 208, extends linearly to the first drive circuit 224. Furthermore, the second wiring 232, also positioned between multiple patch electrodes 208, extends linearly to the second drive circuit 230. The multiple patch electrodes 208 are positioned so that the spacing between them and the first wiring 218 and the second wiring 232 is equal. The patch electrodes positioned in this manner are arranged repeatedly in the first and second directions, with four adjacent patch electrodes 208 forming a second pattern 219.
[0065] Next, referring to Figure 9, the second region 235, which includes the second pattern 219 and its surrounding structure, will be described. Figure 9 shows a plan view of the reflective element 102 shown in Figure 8. The second region 235 shown in Figure 9 is an enlarged view of the second region 235 shown in Figure 8.
[0066] The second pattern 219 includes a first patch electrode 208-1, a second patch electrode 208-2, a third patch electrode 208-3, and a fourth patch electrode 208-4.
[0067] The distance a1 between the first patch electrode 208-1 and the first wiring 218 is equal to the distance a2 between the second patch electrode 208-2 and the first wiring 218. The distance b1 between the first patch electrode 208-1 and the second wiring 232 is equal to the distance b3 between the third patch electrode 208-3 and the second wiring 232. The distance a3 between the third patch electrode 208-3 and the first wiring 218 is equal to the distance a4 between the fourth patch electrode 208-4 and the first wiring 218. The distance b4 between the fourth patch electrode 108-4 and the second wiring 232 is equal to the distance b2 between the second patch electrode 208-2 and the second wiring 232.
[0068] Spacing a1 and a2 are different from spacing a3 and a4. Therefore, the spacing between the first patch electrode 208-1 and the second patch electrode 208-2 is different from the spacing between the third patch electrode 208-3 and the fourth patch electrode 208-4. Spacing b1 and b3 are different from spacing b2 and b4. Therefore, the spacing between the first patch electrode 208-1 and the third patch electrode 208-3 is different from the spacing between the second patch electrode 208-2 and the fourth patch electrode 208-4.
[0069] The first patch electrode 208-1 and the fourth patch electrode 208-4, located diagonally opposite it, are rectangular in shape. The length of the long side W1 of the first patch electrode 208-1 is equal to the length of the short side H4 of the fourth patch electrode 208-4. Similarly, the length of the short side H1 of the first patch electrode 208-1 is equal to the length of the long side H4 of the fourth patch electrode 208-4. Therefore, the area of the first patch electrode 208-1 is equal to the area of the fourth patch electrode 208-4, and they are of the same size.
[0070] In a plan view, the major axis of the first patch electrode 208-1 aligns with the second wiring 232, and the major axis of the fourth patch electrode 208-4 aligns with the first wiring 218. Therefore, the first patch electrode 208-1 and the fourth patch electrode 208-4 have equal major and minor sides, but are positioned in different orientations. Here, the major axis of the first patch electrode 208-1 is defined by the width W1, which is the major side of the first patch electrode 208-1. The major axis of the fourth patch electrode 208-4 is defined by the length H4, which is the major side of the fourth patch electrode 208-4.
[0071] The second patch electrode 208-2 and the third patch electrode 208-3 located diagonally opposite it are square in shape. The side lengths H2 and W2 of the second patch electrode 208-2 are equal. The side lengths H3 and W3 of the third patch electrode 208-3 are equal. The area of the second patch electrode 208-2 is different from the area of the third patch electrode 208-3. The area of the second patch electrode 208-2 is greater than the area of the third patch electrode 208-3. Therefore, the side lengths H2 and W2 of the second patch electrode 208-2 are longer than the side lengths H3 and W3 of the third patch electrode 208-3.
[0072] As described above, the radio wave reflector 200 according to one embodiment of the present invention has patch electrodes that are square in shape but of different sizes, and patch electrodes that are rectangular in shape but have the same long and short sides but with different orientations of their long axes, and the wiring for supplying power to the patch electrodes that extends between these patch electrodes 208 is arranged at equal intervals with respect to the patch electrodes 208. By arranging the wiring in this way and making the patch electrodes 208 rectangular, the influence of radio waves from each wiring to the patch electrodes 208 can be suppressed, and a drop in the reflection amplitude at a certain frequency of the reflecting element 202, which expands the variable range in which radio waves are reflected by patch electrodes 208 of different sizes, can be avoided. By avoiding a drop in the reflection amplitude, the radio wave reflector 200 can increase the amount of phase change of radio waves and further improve the reflection intensity.
[0073] The embodiments described above as embodiments of the present invention can be combined and implemented as appropriate, insofar as they do not contradict each other. Furthermore, any additions, deletions, or design changes made by those skilled in the art based on these embodiments, or additions, omissions, or changes in processes, are also included within the scope of the present invention, as long as they retain the essence of the present invention.
[0074] Any effects or benefits other than those brought about by the embodiments described above, if they are clear from the description herein or easily predictable to a person skilled in the art, are naturally considered to be brought about by the present invention.
[0075] <Examples> Next, examples will be described. The present invention will be described in more detail below with reference to examples and specific examples, but the present invention is not limited to the following examples.
[0076] This embodiment describes the results of a simulation of the amplitude (dB) in a radio wave reflector using two different sizes of patch electrodes. The simulation assumes a reflector for a radio wave reflector where, as shown in Figure 9, two adjacent patch electrodes and the first and second wirings 218 and 232 placed between them are arranged at equal intervals (embodiment), and a comparative example where the first and second wirings are not arranged at equal intervals between the patch electrodes (comparative example), although this is not shown. The patch electrodes are square in shape; for example, the size of patch electrode 208-3 is 2.5 mm × 2.5 mm, which is 6.25 mm. 2 The patch electrode has a rectangular shape, for example, the size of patch electrode 208-4 is 7.00 mm, compared to 2.8 mm x 2.5 mm. 2 The first wiring 218 is positioned at equal intervals with respect to patch electrodes 208-3 and 208-4, and the distance between the patch electrodes and the wiring is 1.05 mm. When the wiring is not positioned at equal intervals with respect to the patch electrodes, the distances between the patch electrodes and the wiring are 0.45 mm and 0.60 mm. The thickness of the liquid crystal layer 114 of the reflector elements 102a and 102b is 75 μm. The dielectric constant of the liquid crystal layer 114 is from 2.5ε0F / m to 3.5ε0F / m (ε0 is the dielectric constant of vacuum). The dielectric constant is a variable range from when no voltage is applied to the liquid crystal layer 114 to when a voltage is applied. The simulation was performed using CST Studio Suite (manufactured by Dassault Systèmes K.K.).
[0077] The simulation results showed that, within the variable dielectric constant range, the average reflection amplitude for vertical polarization was -5.1 dB for the example compared to -7.6 dB for the comparative example. Furthermore, within the variable dielectric constant range, the average reflection amplitude for horizontal polarization was -5.3 dB for the example compared to -6.4 dB for the comparative example. Therefore, it was found that the wiring arrangement in the example improved the reflection amplitude by more than 1.1 dB compared to the wiring arrangement in the comparative example. [Explanation of symbols]
[0078] 100: Radio wave reflector, 102: Reflector element, 102a: First reflector element, 102b: Second reflector element, 104: Dielectric substrate, 104: Dielectric substrate (dielectric layer), 106: Opposing substrate, 108: Patch electrode, 108-1: First patch electrode, 108-2: Second patch electrode, 108-3: Third patch electrode, 108-4: Fourth patch electrode, 109: Connection wiring, 110: Common Electrode, 112a: First alignment layer, 112b: Second alignment layer, 114: Liquid crystal layer, 116: Liquid crystal molecule, 118: First wiring, 119: First pattern, 120: Radio wave reflector, 122: Peripheral region, 124: First drive circuit, 126: Terminal section, 128: Sealing material, 130: Second drive circuit, 132: Second wiring, 134: Switching element, 135: First region, 136: Undercoat 138: First gate electrode, 140: First gate insulating layer, 142: Semiconductor layer, 144: First connection wiring, 146: Second gate insulating layer, 148: Second gate electrode, 150: First interlayer insulating layer, 152: Second connection wiring, 154: Second interlayer insulating layer, 156: Planarization layer, 158: Passivation layer, 160: First bend, 162: Second bend, 200: Radio wave reflector 202: Reflector element, 204: Dielectric substrate (dielectric layer), 208: Patch electrode, 208-1: First patch electrode, 208-2: Second patch electrode, 208-3: Third patch electrode, 208-4: Fourth patch electrode, 218: First wiring, 219: Second pattern, 220: Radio wave reflector, 224: First drive circuit, 230: Second drive circuit, 232: Second wiring, 235: Second region
Claims
1. First patch electrode and, The first patch electrode and the second patch electrode adjacent to it, A third patch electrode adjacent to the first patch electrode, A fourth patch electrode adjacent to the second patch electrode and the third patch electrode, A common electrode facing the first patch electrode and the second patch electrode, The liquid crystal layer between the first patch electrode and the second patch electrode and the common electrode, A first wiring between the first patch electrode and the second patch electrode, The area of the first patch electrode is different in size from the areas of the second patch electrode and the third patch electrode. The distance between the first patch electrode and the first wiring is equal to the distance between the second patch electrode and the first wiring. Radio wave reflector.
2. The first wiring has a first bend, The radio wave reflector according to claim 1.
3. The first wiring extends between the third patch electrode and the fourth patch electrode, The first bent portion is positioned between the first patch electrode and the fourth patch electrode. The radio wave reflector according to claim 2.
4. The distance between the first patch electrode and the first bent portion is equal to the distance between the fourth patch electrode and the first bent portion. The radio wave reflector according to claim 3.
5. The areas of the first patch electrode and the fourth patch electrode are equal, The areas of the second patch electrode and the third patch electrode are equal. The radio wave reflector according to claim 3.
6. The device further includes a second wiring extending between the first patch electrode and the third patch electrode and between the second patch electrode and the fourth patch electrode, The second wiring has a second bend between the second patch electrode and the third patch electrode. The radio wave reflector according to claim 3.
7. In cross-sectional view, an insulating layer is further provided between the first bent portion and the second bent portion. The first bent portion and the second bent portion overlap. The radio wave reflector according to claim 6.
8. The first switching element is further electrically connected to the first patch electrode, The first switching element is electrically connected to the first wiring. The radio wave reflector according to claim 1.
9. The distance between the third patch electrode and the first wiring and the distance between the fourth patch electrode and the first wiring are equal, The areas of the second patch electrode and the third patch electrode are different. The radio wave reflector according to claim 1.
10. The distance between the first patch electrode and the second patch electrode and the distance between the third patch electrode and the fourth patch electrode are different. The radio wave reflector according to claim 9.
11. The device further includes a second wiring extending between the first patch electrode and the third patch electrode and between the second patch electrode and the fourth patch electrode, The distance between the first patch electrode and the second wiring and the distance between the third patch electrode and the second wiring are equal. The distance between the second patch electrode and the second wiring is equal to the distance between the fourth patch electrode and the second wiring. The radio wave reflector according to claim 9.
12. The distance between the first patch electrode and the third patch electrode is different from the distance between the second patch electrode and the fourth patch electrode. The radio wave reflector according to claim 11.
13. The areas of the first patch electrode and the fourth patch electrode are equal, The distance between the first patch electrode and the second patch electrode is equal to the distance between the second patch electrode and the fourth patch electrode. The radio wave reflector according to claim 9.
14. The first patch electrode and the fourth patch electrode are rectangular. The long axis of the first patch electrode is aligned with the second wiring, The long axis of the fourth patch electrode is aligned with the first wiring. The radio wave reflector according to claim 11.