Radio wave reflecting device

Abstract

The radio wave reflecting device is provided with a patch electrode, a common electrode opposite to and isolated from the patch electrode, and a liquid crystal layer between the patch electrode and the common electrode. The patch electrode has, in plan view, a cross shape including a first rectangular pattern extending in a first direction and a second rectangular pattern extending in a second direction intersecting the first direction and intersecting the first rectangular pattern. The common electrode has, in plan view, a first band-shaped pattern extending in the first direction, and a second band-shaped pattern extending in the second direction and intersecting the first band-shaped pattern.

Description

Technical Field

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

[0002] Phased array antenna devices control directivity while the antenna is fixed by adjusting the amplitude and phase of the applied high-frequency signal to each of the multiple antenna elements arranged in a planar shape. Phased array antenna devices require phase shifters. A phased array antenna device using a phase shifter that utilizes the change in dielectric constant caused by the orientation state of liquid crystals is disclosed (for example, see Patent Document 1). In addition, as an example of a radio wave reflection device, a liquid crystal metal reflector that utilizes the dielectric anisotropy of liquid crystals to change the direction of radio wave reflection is disclosed (for example, see Patent Document 2).

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 11-103201

[0006] Patent Document 2: Japanese Patent Application No. 2019-530387 Summary of the Invention

[0007] Problems to be solved by the invention

[0008] In the increasingly widespread fifth-generation mobile communication system (5G), the use of radio wave reflection devices is being studied to simplify radio wave base stations. Radio wave reflection devices with a constant dielectric constant reflect radio waves in a fixed direction. On the other hand, as disclosed in Patent Document 2, radio wave reflection devices using liquid crystal materials as dielectrics can change the direction of radio wave reflection by applying a voltage to the liquid crystals.

[0009] However, the above-mentioned radio wave reflecting device has a problem in that the electrodes are made of metal and are opaque, thereby affecting the view of the installation site.

[0010] In view of such problems, one of the objectives of one embodiment of the present invention is to provide a radio wave reflecting device that does not affect the landscape and can control the reflection of 5G radio waves in a desired direction and has high reflection characteristics.

[0011] Means for solving problems

[0012] An electric wave reflecting device according to one embodiment of the present invention comprises a patch electrode, a common electrode opposite to and isolated from the patch electrode, and a liquid crystal layer between the patch electrode and the common electrode. The patch electrode, when viewed from above, has a cross shape comprising a first rectangular pattern extending in a first direction and a second rectangular pattern extending in a second direction intersecting the first direction and intersecting the first rectangular pattern. The common electrode, when viewed from above, has a first stripe pattern extending in the first direction and a second stripe pattern extending in the second direction and intersecting the first stripe pattern. The first rectangular pattern and the second rectangular pattern of the patch electrode overlap with the common electrode. The patch electrode has a plurality of first through holes in the first rectangular pattern and the second rectangular pattern. The common electrode has a second through hole in the first stripe pattern and the second stripe pattern. The first through hole overlaps with the second through hole. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 A cross-sectional view showing a reflecting element used in a radio wave reflecting device according to an embodiment of the present invention.

[0014] Figure 2 A plan view showing a reflecting element used in a radio wave reflecting device according to an embodiment of the present invention.

[0015] Figure 3 A plan view showing a second substrate in the radio wave reflection device according to one embodiment of the present invention.

[0016] Figure 4 A plan view showing a reflecting element used in a radio wave reflecting device according to an embodiment of the present invention.

[0017] Figure 5 A plan view showing a second substrate in the radio wave reflection device according to one embodiment of the present invention.

[0018] Figure 6 A plan view showing a reflecting element used in a radio wave reflecting device according to an embodiment of the present invention.

[0019] Figure 7 A plan view showing a second substrate in the radio wave reflection device according to one embodiment of the present invention.

[0020] Figure 8A FIG. 1 shows a state in which a reflecting element used in a radio wave reflecting device according to an embodiment of the present invention operates, and shows a state in which no voltage is applied between the patch electrode and the common electrode.

[0021] Figure 8B The diagram shows a state in which a reflecting element used in a radio wave reflecting device according to an embodiment of the present invention operates, and shows a state in which a voltage is applied between the patch electrode and the common electrode.

[0022] Figure 9A plan view showing a radio wave reflecting device according to an embodiment of the present invention.

[0023] Figure 10 A plan view showing a second substrate in the radio wave reflection device according to one embodiment of the present invention.

[0024] Figure 11 A plan view showing a second substrate in the radio wave reflection device according to one embodiment of the present invention.

[0025] Figure 12 The following schematically shows how the traveling direction of a reflected wave changes due to a radio wave reflecting device according to one embodiment of the present invention.

[0026] Figure 13 A plan view showing a radio wave reflecting device according to an embodiment of the present invention.

[0027] Figure 14 A cross-sectional view showing a reflecting element in a radio wave reflecting device according to an embodiment of the present invention. DETAILED DESCRIPTION

[0028] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings and the like. However, the present invention can be implemented in a number of different ways and is not limited to the description of the embodiments illustrated below. In order to make the description clearer, the accompanying drawings sometimes schematically show the width, thickness, shape, etc. of each part compared to the actual method, but this is only an example and does not limit the interpretation of the present invention. In addition, in this specification and the figures, the same elements as those described in the preceding figures are sometimes marked with the same figure mark (or with a, b, etc. after the number), and detailed descriptions are appropriately omitted. In addition, the words "1st" and "2nd" marked for each element are identifiers used to distinguish the elements, and have no further meaning unless otherwise specified.

[0029] In this specification, when a component or area is located "above (or below)" other components or areas, unless otherwise specified, it includes not only the case where it is located directly above (or directly below) other components or areas, but also the case where it is located above (or below) other components or areas, that is, the case where other components are included above (or below) other components or areas.

[0030] 1. Reflective element

[0031] Figure 1 A cross-sectional view of a reflecting element 102 used in a radio wave reflecting device according to an embodiment of the present invention is shown.

[0032] like Figure 1As shown, the reflective element 102 includes a first substrate 104, a second substrate 106, a patch electrode 108, a common electrode 110, a liquid crystal layer 114, and alignment films 112a and 112b. The patch electrode 108 is provided on the first substrate 104, and the common electrode 110 is provided on the second substrate 106. The reflective element 102 is configured with the first substrate 104 having the patch electrode 108 provided on the radio wave incident side. An alignment film 112a is provided on the first substrate 104 to cover the patch electrode 108, and an alignment film 112b is provided on the second substrate 106 to cover the common electrode 110. The patch electrode 108 and the common electrode 110 are arranged opposite and spaced apart from each other. The common electrode 110 is arranged on the back side of the patch electrode 108. The liquid crystal layer 114 is provided between the patch electrode 108 and the common electrode 110. An alignment film 112 a is interposed between the patch electrode 108 and the liquid crystal layer 114 , and an alignment film 112 b is interposed between the common electrode 110 and the liquid crystal layer 114 .

[0033] The patch electrode 108 has a plurality of first through holes 109. The common electrode 110 has a plurality of second through holes 113 that overlap with the plurality of first through holes 109. For example, Figure 1 As shown, the plurality of first through-holes 109 overlap with the plurality of second through-holes 113 when viewed in cross section. The widths W1 of the plurality of first through-holes 109 and the widths W1 of the plurality of second through-holes 113 are equal or substantially equal. The plurality of first through-holes 109 are arranged at equal intervals D1. Since the plurality of second through-holes 113 have the same width as the plurality of first through-holes 109 and overlap, they can also be arranged at equal intervals D1.

[0034] like Figure 1 As shown, the plurality of first through holes 109 overlap with the plurality of second through holes 113, and the width W1 of the plurality of first through holes 109 is equal to the width W1 of the plurality of second through holes 113. Thus, visible light incident from the first substrate 104 and the second substrate 106 can pass through the plurality of first through holes 109 and the plurality of second through holes 113, thereby improving the light transmittance (transparency) of the reflective element 102.

[0035] Next, refer to Figure 2 The patch electrode 108 will be described. Figure 2 1 is a top view of the reflective element 102 as viewed from above (radio wave incident side). Figure 1 Show Figure 2 A cross-sectional view between A1-A2 is shown.

[0036] The patch electrode 108 preferably has a symmetrical shape with respect to the vertically polarized wave and the horizontally polarized wave of the incident radio wave, and preferably has a cross shape when viewed from above. The cross shape of the patch electrode 108 includes a first direction (for example, Figure 2The first rectangular pattern 108-1 extending in the X-axis direction shown in FIG. 1 and the second rectangular pattern 108-1 extending in the second direction (eg, Figure 2 Second rectangular pattern 108-2 extends in the Y-axis direction (as shown) and intersects first rectangular pattern 108-1 at intersection 108C. Here, the first direction is parallel to the vibration direction of the vertically polarized wave or the horizontally polarized wave, and the second direction is parallel to the vibration direction of the cross-polarized wave, which intersects the vertically polarized wave or the horizontally polarized wave. The lengths of first rectangular pattern 108-1 and second rectangular pattern 108-2 are appropriately set according to the wavelength of the incident radio wave.

[0037] The patch electrode 108 has a plurality of first through holes 109 in the first rectangular pattern 108-1 and the second rectangular pattern 108-2. The patch electrode 108 is provided with a plurality of first through holes 109 having a dot pattern. The plurality of first through holes 109 are arranged along the first direction. The plurality of first through holes 109 are arranged in a plurality of columns in the first rectangular pattern 108-1. The plurality of first through holes 109 are arranged in a plurality of columns in the second rectangular pattern 108-2. At this time, the first direction is a direction different from the second direction, and is preferably orthogonal to the second direction. Figure 1 , an example is shown in which the plurality of first through holes 109 are arranged in three rows each in the first direction and the second direction. However, a plurality of first through holes 109 may be provided in the patch electrode 108, and the number of rows is not limited.

[0038] The plurality of first through holes 109 can be arranged at equal intervals in the first direction. Figure 2 As shown, the intervals D1 and D2 of the plurality of first through holes 109 arranged in the first direction can be made equal or substantially equal. The plurality of first through holes 109 can be arranged at equal intervals in the second direction. For example, Figure 2 As shown, the intervals D3 and D4 between the plurality of first through holes 109 arranged in the second direction can be made equal or substantially equal.

[0039] As described above, the widths of the plurality of first through holes 109 can be made equal. Figure 2 As shown, in the first direction, the width W1 and the width W2 of the first through hole 109 can be equal or substantially equal. In the second direction, the width W3 and the width W4 of the first through hole 109 can be equal or substantially equal.

[0040] The plurality of first through holes 109 are holes that penetrate the patch electrode 108 and can have various shapes in a plan view. Figure 2The example in which the plurality of first through holes 109 are square in plan view is shown. The shape of the plurality of first through holes 109 in plan view is not limited to a square, and may be a polygon with more than 4 sides, such as a rectangle, a circle, an ellipse, or a hexagon.

[0041] When the plurality of first through holes 109 are rectangular in a plan view, the shape of the plurality of first through holes 109 includes a first side 109S1 and a second side 109S2. The first side 109S1 is parallel or substantially parallel to the direction in which the first rectangular pattern 108-1 extends. Preferably, the first side 109S1 is parallel or substantially parallel to the polarized wave. The second side 109S2 is parallel or substantially parallel to the direction in which the second rectangular pattern 108-2 extends. Preferably, the second side 109S2 is parallel or substantially parallel to the polarized wave.

[0042] As described above, the patch electrode 108 can have a higher aperture ratio by having a plurality of first through-holes 109. The increased aperture ratio of the patch electrode 108 can improve light transmittance (transparency). The aperture ratio of the patch electrode 108 represents the ratio of the opening area of ​​the first through-holes 109 per unit area of ​​the patch electrode 108.

[0043] The patch electrode 108 has a plurality of first through-holes 109, thereby improving the aesthetics of the vertical and horizontal stripes of the patch electrode 108. Furthermore, by arranging the first side 109S1 and the second side 109S2 of the first through-hole 109 to be parallel or substantially parallel to the direction in which the first rectangular pattern 108-1 and the second rectangular pattern 108-2 extend, respectively, the patch electrode 108 can improve its reflection characteristics against radio waves.

[0044] Next, refer to Figure 3 The common electrode 110 having the second through hole 113 overlapping with the first through hole 109 will be described. Figure 3 A top view of the second substrate in the radio wave reflection device according to one embodiment of the present invention is shown. Specifically, Figure 3 A common electrode 110 corresponding to one reflective element 102 is shown.

[0045] The common electrode 110 has an opening 111 outside the region overlapping with the patch electrode 108. Therefore, the common electrode 110 has a cross shape in the reflective element 102. In other words, it has a cross shape along the first direction ( Figure 3 The first stripe pattern 110-1 extending in the Y-axis direction shown in FIG. 1 and the second stripe pattern 110-1 extending in the second direction ( Figure 3 The second strip patterns 110-2 extending in the X-axis direction (shown) intersect at the intersection portion 110C.

[0046] The cross shape of the common electrode 110 is arranged so as to overlap with the cross shape of the patch electrode 108. Figure 1 As shown in the cross-sectional view, the first strip pattern 110-1 overlaps with the first rectangular pattern 108-1. In addition, the second strip pattern 110-2 also overlaps with the second rectangular pattern 108-2 when observed in cross section. It should be noted that when the reflective elements 102 are arranged in a matrix, they are arranged independently relative to the patch electrodes 108, and the common electrodes 110 are connected in the matrix arrangement to form a grid pattern. That is, Figure 3 The first band pattern 110-1 shown is Figure 9 The radio wave reflection device shown is a part of the first strip pattern 110-1, and the second strip pattern 110-2 is Figure 9 A portion of the second stripe pattern 110 - 2 is shown.

[0047] The common electrode 110 has a plurality of second through holes 113 in the first stripe pattern 110-1 and the second stripe pattern 110-2. The common electrode 110 has a plurality of second through holes 113 in a dot pattern. The plurality of second through holes 113 in a dot pattern are arranged in a plurality of rows in the first stripe pattern 110-1 and the second stripe pattern 110-2. Figure 3 In the embodiment, three rows of the plurality of second through holes 113 are shown for one first stripe-shaped pattern 110 - 1 and one second stripe-shaped pattern 110 - 2 , but the number of rows is not limited.

[0048] The plurality of second through holes 113 are as follows Figure 1 As shown, it is located at a position overlapping with the plurality of first through holes 109. Therefore, the intervals between the adjacent plurality of second through holes 113 are equal or substantially equal. Figure 3 As shown, the intervals D1 and D2 of the plurality of second through holes 113 arranged in the first direction can be equal or substantially equal. The plurality of second through holes 113 can be arranged at equal intervals in the second direction. For example, Figure 3 As shown, the intervals D3 and D4 between the plurality of second through holes 113 arranged in the second direction can be made equal or substantially equal.

[0049] In addition, the plurality of second through holes 113 can make the shapes and areas of the plurality of first through holes 109 equal or approximately equal. The plurality of second through holes 113 can be set to a rectangle when viewed from above. The shape of the plurality of second through holes 113 includes a first side 113S1 and a second side 113S2. The first side 113S1 is a side that is parallel or approximately parallel to the direction in which the first strip pattern 110-1 extends. The second side 113S2 is a side that is parallel or approximately parallel to the direction in which the second strip pattern 110-2 extends. In addition, the lengths of the first side 113S1 and the second side 113S2 can also be equal or approximately equal. For example, as Figure 3 As shown, the lengths of the first side 113S1 and the second side 113S2 can be made equal, and the shape of the plurality of second through holes 113 can be set to a square. The shape of the plurality of second through holes 113 in a plan view can be equal to the shape of the first through hole 109 and is not limited to a square. A polygon with more than four sides, such as a rectangle, a circle, an ellipse, or a hexagon, can also be used.

[0050] The common electrode 110 can increase its aperture ratio by having a plurality of second through-holes 113 and a plurality of openings 111, thereby improving the light transmittance (transparency) of the common electrode 110. Furthermore, the common electrode 110 can improve the aesthetics of the vertical and horizontal stripes of the common electrode 110 by having a plurality of second through-holes 113. Furthermore, by setting the first side 113S1 of the second through-hole 113 to be parallel or substantially parallel to the direction in which the first strip-shaped pattern 110-1 extends, and setting the second side 113S2 to be parallel or substantially parallel to the direction in which the second strip-shaped pattern 110-2 extends, the common electrode 110 can improve its reflection characteristics with respect to radio waves.

[0051] As described above, the plurality of first through holes 109 provided in the patch electrode 108 and the plurality of second through holes 113 provided in the common electrode 110 can have different shapes and arrangements. Figure 4 and Figure 5 The shapes and arrangements of the plurality of first through-holes 109 and the plurality of second through-holes 113 will be described.

[0052] The plurality of first through holes 109 can be alternately arranged in the patch electrode 108 . Figure 4 and Figure 5 A plan view showing a reflecting element used in a radio wave reflecting device according to an embodiment of the present invention.

[0053] The plurality of first through holes 109 can be arranged in a checkerboard pattern. Figure 4 As shown, the plurality of first through holes 109 can be arranged at the diagonal positions. Since the plurality of first through holes 109 are arranged at the diagonal positions, the first rectangular pattern 108-1 and the second rectangular pattern 108-2 are interrupted by the plurality of first through holes 109. For example, Figure 4 As shown in FIG. 1 , if the space between the plurality of first through holes 109 adjacent in the second direction is defined as the straight portion 108L1 of the first rectangular pattern 108-1, the patch electrode 108 of the straight portion 108L1 is interrupted by the plurality of first through holes 109. Similarly, the second rectangular pattern 108-2 is interrupted by the plurality of first through holes 109. For example, Figure 4As shown, if the area between the plurality of first through-holes 109 adjacent to each other in the first direction is defined as the straight portion 108L2 of the second rectangular pattern 108 - 2 , the patch electrode 108 in the straight portion 108L2 is divided by the plurality of first through-holes 109 .

[0054] The plurality of second through holes 113 are alternately arranged in the common electrode 110. The plurality of second through holes 113 are arranged in a checkerboard pattern. Figure 5 As shown, the plurality of second through holes 113 are arranged at the diagonal positions. Since the plurality of second through holes 113 are arranged at the diagonal positions, the first strip pattern 110-1 and the second strip pattern 110-2 are interrupted by the plurality of second through holes 113. Figure 5 As shown in FIG. 1 , if the area between the plurality of second through holes 113 adjacent in the second direction is set as the straight portion 110L1 of the first strip-shaped pattern 110-1, the common electrode 110 of the straight portion 110L1 is interrupted by the plurality of second through holes 113. Similarly, the second strip-shaped pattern 110-2 is interrupted by the plurality of second through holes 113. For example, Figure 5 As shown, if the area between the plurality of second through-holes 113 adjacent to each other in the first direction is defined as the straight portion 110L2 of the second stripe pattern 110 - 2 , the common electrode 110 in the straight portion 110L2 is divided by the plurality of second through-holes 113 .

[0055] The plurality of first through holes 109 and the plurality of second through holes 113 are arranged in a checkerboard pattern, thereby further improving the aesthetics of the vertical and horizontal stripes.

[0056] Reference Figure 6 and Figure 7 The shapes and arrangements of the plurality of first through holes 109 and the plurality of second through holes 113 , which are different from the shapes and arrangements described above, will be described. Figure 6 and Figure 7 A plan view showing a reflecting element used in a radio wave reflecting device according to an embodiment of the present invention.

[0057] The plurality of first through holes 109 include a slit pattern 109-1 extending along the first rectangular pattern 108-1 and a slit pattern 109-2 extending along the second rectangular pattern 108-2. Figure 6 As shown, the slit pattern 109-2 opens on the patch electrode 108 so as to be elongated in the longitudinal direction of the first rectangular pattern 108-1. The slit pattern 109-2 opens on the patch electrode 108 so as to be elongated in the longitudinal direction of the second rectangular pattern 108-2.

[0058] The first through holes 109 have a plurality of dot patterns 109-3 at the intersection 108C of the first rectangular pattern 108-1 and the second rectangular pattern 108-2. The dot pattern 109-3 has a shape as shown in FIG. Figure 6 The dot pattern 109-3 is different from the slit pattern 109-2 in shape and can be, for example, a square with four sides of equal length.

[0059] The plurality of second through holes 113 include a slit pattern 113-1 extending along the first stripe pattern 110-1 and a slit pattern 113-2 extending along the second stripe pattern 110-2. Figure 7 As shown, the slit pattern 113-2 opens on the common electrode 110 so as to be elongated in the longitudinal direction of the first stripe pattern 110-1. The slit pattern 113-2 opens on the common electrode 110 so as to be elongated in the longitudinal direction of the second stripe pattern 110-2.

[0060] The second through holes 113 include a plurality of dot patterns 113-3 at the intersection 110C between the first stripe pattern 110-1 and the second stripe pattern 110-2. The dot pattern 113-3 has a shape different from the slit pattern 113-2 and can be, for example, a square with four sides of equal length.

[0061] By providing multiple through holes with a slit pattern and multiple through holes with a dot pattern in the patch electrode 108 and the common electrode 110 , the radio wave reflection device can further increase the phase change amount and obtain higher reflection characteristics.

[0062] Here again, refer to Figure 1 The main structure of the reflective element 102 will be described.

[0063] The first substrate 104 and the second substrate 106 are bonded together by a sealing material to be described later (see Figure 6 ). The first substrate 104 and the second substrate 106 are arranged relative to each other with a gap therebetween, and the liquid crystal layer 114 is provided in an area surrounded by a sealing material. The liquid crystal layer 114 is provided in a manner to fill the gap between the first substrate 104 and the second substrate 106. The gap between the first substrate 104 and the second substrate 106 is 30-100 μm, for example, a gap of 50 μm. Since the patch electrode 108, the common electrode 110, the orientation film 112a, and the orientation film 112b are provided between the first substrate 104 and the second substrate 106, to be precise, the gap between the orientation film 112a and the orientation film 112b provided on each of the first substrate 104 and the second substrate 106 becomes the thickness of the liquid crystal layer 114. It should be noted that, Figure 5 A and Figure 5Although not shown in FIG. 1B , a spacer may be provided between the first substrate 104 and the second substrate 106 to keep the distance therebetween constant.

[0064] A control signal that controls 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 DC voltage or a polarity-reversed signal that alternates between positive and negative DC voltages. A ground (common) voltage or a voltage intermediate the polarity-reversed signal is applied to the common electrode 110. Application of the control signal to the patch electrode 108 changes the alignment of the liquid crystal molecules in the liquid crystal layer 114.

[0065] Materials that reflect visible light can be used for the patch electrode 108 and the common electrode 110. Furthermore, a metal material with low specific resistance can be used to form the patch electrode 108. For example, a metal film such as aluminum (Al) or copper (Cu) can be used to form the common electrode 110.

[0066] Liquid crystal layer 114 uses a liquid crystal material with dielectric anisotropy. For example, nematic liquid crystal, smectic liquid crystal, cholesteric liquid crystal, or discotic liquid crystal can be used as liquid crystal layer 114. The dielectric constant of liquid crystal layer 114 with dielectric anisotropy changes depending on the orientation of the liquid crystal molecules. Reflective element 102 can change the dielectric constant of liquid crystal layer 114 using a control signal applied to patch electrode 108, thereby delaying the phase of the reflected wave when reflecting radio waves.

[0067] The frequency bands of radio waves reflected by reflective element 102 include the very high frequency (VHF) band, the ultra-high frequency (UHF) band, the microwave (SHF) band, the submillimeter wave (THF) band, and the extra high frequency (EHF) band. The liquid crystal molecules in liquid crystal layer 114 change their orientation in response to the control signal applied to patch electrode 108, but they rarely follow the frequency of the radio waves irradiating patch electrode 108. Therefore, reflective element 102 can control the phase of the reflected radio waves without being affected by the radio waves.

[0068] Next, refer to Figure 8A and Figure 8B The alignment state of the liquid crystal layer 114 when a voltage is applied to the patch electrode 108 and the common electrode 110 of the reflective element 102 will be described.

[0069] Figure 8AA state (referred to as a “first state”) in which no voltage is applied between the patch electrode 108 and the common electrode 110 is shown. Figure 8A The alignment films 112a and 112b are horizontal alignment films. In the first state, the long axes of the liquid crystal molecules 116 are aligned horizontally with respect to the surfaces of the patch electrode 108 and the common electrode 110 by the alignment films 112a and 112b. Figure 8B The figure shows a state (referred to as "second state") in which a control signal (voltage signal) is applied to patch electrode 108. In the second state, liquid crystal molecules 116 are subjected to an electric field, aligning their long axes perpendicularly to the surfaces of patch electrode 108 and common electrode 110. The angle of the long axis of liquid crystal molecules 116 can also be adjusted to an intermediate direction between horizontal and vertical, depending on the magnitude of the control signal applied to patch electrode 108 (the magnitude of the voltage between the counter electrode and the patch electrode).

[0070] When the liquid crystal molecules 116 have positive dielectric anisotropy, the dielectric constant in the second state is greater than that in the first state. On the other hand, when the liquid crystal molecules 116 have negative dielectric anisotropy, the apparent dielectric constant in the second state is smaller than that in the first state. The liquid crystal layer 114 having dielectric anisotropy can also be considered a variable dielectric layer. The reflective element 102 can be controlled to delay (or not delay) the phase of the reflected wave by utilizing the dielectric anisotropy of the liquid crystal layer 114.

[0071] According to this embodiment, the patch electrode 108 includes a cross shape having a first rectangular pattern 108-1 extending along a first direction and a second rectangular pattern 108-2 extending along a second direction intersecting the first direction and intersecting the first rectangular pattern 108-1, and has a plurality of first through holes 109. The common electrode 110 has a plurality of second through holes 113 in the first strip pattern 110-1 and the second strip pattern 110-2. The plurality of first through holes 109 overlap with the plurality of second through holes 113, thereby achieving high light transmittance, a large phase change, and being able to improve the aesthetics of the vertical and horizontal stripes.

[0072] 2. Radio wave reflection device

[0073] Next, the configuration of a radio wave reflecting device in which the reflecting element 102 is integrated will be described.

[0074] 2-1. Radio wave reflection device A (single-axis reflection control)

[0075] Figure 9 FIG. 1 shows a configuration of a radio wave reflection device 100a according to an embodiment of the present invention. The radio wave reflection device 100a includes a reflection plate 120. The reflection plate 120 is composed of a plurality of reflection elements 102. The plurality of reflection elements 102 are arranged in a first direction ( Figure 9 The X-axis direction shown in FIG) and the second direction intersecting the first direction ( Figure 9 The reflective element 102 is arranged in the Y-axis direction (shown). The patch electrodes 108 face the incident surface of the radio wave. The reflector 120 is a flat plate with a plurality of patch electrodes 108 arranged in a matrix within the plane of the flat plate.

[0076] The radio wave reflection device 100 has a structure in which a plurality of reflection elements 102 are integrated on a first substrate 104. Figure 9 As shown, the radio wave reflection device 100 has a structure in which a first substrate 104 on which a plurality of patch electrodes 108 are arranged overlaps with a second substrate 106 on which a common electrode 110 is provided, and a liquid crystal layer (not shown) is provided between the two substrates. The reflector 120 is formed in the region where the plurality of patch electrodes 108 overlap with the common electrode 110. With respect to each patch electrode 108, the cross-sectional structure of the reflector 120 is similar to that of the first substrate 104. Figure 1 The structure of the reflective element 102 shown is the same. The first substrate 104 and the second substrate 106 are bonded together via a sealant 128 , and a liquid crystal layer (not shown) is provided in a region inside the sealant 128 .

[0077] In addition to the area facing the second substrate 106, the first substrate 104 also has a peripheral area 122 that extends outward from the second substrate 106. A first drive circuit 124 and a terminal portion 126 are provided in the peripheral area 122. The first drive circuit 124 outputs a control signal to the patch electrode 108. The terminal portion 126 is a region for connection to an external circuit, for example, a flexible printed circuit board (not shown). Signals for controlling the first drive circuit 124 are input to the terminal portion 126.

[0078] As described above, a plurality of patch electrodes 108 are arranged along the first direction (X-axis direction) and the second direction (Y-axis direction) on the first substrate 104. In addition, a plurality of first wirings 118 extending along the second direction (Y-axis direction) are arranged on the first substrate 104. The plurality of first wirings 118 are electrically connected to the plurality of patch electrodes 108 arranged in the second direction (Y-axis direction), respectively. In other words, the plurality of patch electrodes 108 arranged in the second direction (Y-axis direction) are connected by the first wirings 118. The reflector 120 has a structure of a column of patch electrode arrays arranged in the first direction (X-axis direction) and connected by the first wirings 118. In Figure 9 , an example is shown in which the patch electrodes 108 are connected in an arrangement in the first direction (Y-axis direction).

[0079] The plurality of first wirings 118 arranged on the reflector 120 extend within the peripheral region 122 and are connected to a first drive circuit 124. The first drive circuit 124 outputs a control signal applied to the patch electrodes 108. The first drive circuit 124 can output control signals of different voltage levels to each of the plurality of first wirings 118. Thus, on the reflector 120, control signals are applied column by column (to each patch electrode 108 arranged in the second direction (Y-axis direction)) to the plurality of patch electrodes 108 arranged in the first direction (X-axis direction) and the second direction (Y-axis direction).

[0080] On the second substrate 106, a common electrode 110 is provided in a shape extending over substantially the entire surface of the second substrate 106 so as to overlap with the plurality of patch electrodes 108. Figure 9 As shown, the common electrode 110 is formed to have a larger area than the patch electrode 108 .

[0081] Reference Figure 10 The common electrode 110 provided on the second substrate 106 will be described. Figure 10 Illustration of the plurality of second through holes 113 in the common electrode 110 is omitted.

[0082] The common electrode 110 includes a plurality of first strip-shaped patterns 110-1 extending in the first direction and a plurality of second strip-shaped patterns 110-2 extending in the second direction. Since the common electrode 110 and the patch electrode 108 are arranged to overlap, the intersection 110C of the first strip-shaped patterns 110-1 extending in the first direction and the second strip-shaped patterns 110-2 extending in the second direction overlap with the intersection 108C of the patch electrode 108. Therefore, as described above, the cross shape of the common electrode 110 overlaps with the cross shape of the patch electrode 108. The cross shape of the common electrode 110 and the cross shape of the patch electrode 108 can have sides that are parallel or substantially parallel to the polarized wave. Furthermore, the cross shape of the common electrode 110 and the cross shape of the patch electrode 108 are preferably rotationally symmetrical. The cross-shaped common electrode 110 and the cross-shaped patch electrode 108 that overlap each other have sides parallel or substantially parallel to the polarized wave and are rotationally symmetrical, so that the reflective element 102 has a high reflection characteristic for radio waves.

[0083] As described above, the common electrode 110 has a plurality of openings 111. The common electrode 110 has a mesh-like pattern of openings 111. In other words, the openings 111 are arranged in a matrix on the second substrate 106. The openings 111 are arranged so as not to overlap with the patch electrodes 108.

[0084] Reference Figure 11 Description and Figure 10 The common electrodes shown are common electrodes 110 of different shapes. Figure 11 A plan view of a second substrate used in a radio wave reflection device according to an embodiment of the present invention and an inset view showing an enlarged arrangement of a common electrode 110 corresponding to four reflection elements 102 are shown. Figure 11 Illustration of the plurality of second through holes 113 in the common electrode 110 is omitted.

[0085] The common electrode 110 may have a lattice pattern when viewed from above. The lattice pattern is configured to surround the cross-shaped common electrode 110 corresponding to one reflective element 102. For example, Figure 14 As shown, the lattice pattern has a first linear pattern 110G1 extending in the first direction and a second linear pattern 110G2 extending in the second direction. The first linear pattern 110G1 intersects with the second strip-shaped pattern 110-2 at an intersection 117. The second linear pattern 110G2 intersects with the first strip-shaped pattern 110-1 at an intersection 115. The intersection 115 is located between a plurality of intersections 110C where a plurality of first strip-shaped patterns 110-1 intersect with a plurality of second strip-shaped patterns 110-2. Figure 11 As shown, the intersection portion 115 is located between the plurality of intersection portions 110C arranged in the first direction.

[0086] Since the common electrode 110 further has a lattice pattern, the phase change amount of the radio wave reflection device can be further increased, and higher reflection characteristics can be obtained.

[0087] It should be noted that Figure 10 and Figure 11 The first strip pattern 110-1 and the second strip pattern 110-2 are shown by Figure 3 The first band pattern 110-1 and the second band pattern 110-2 shown are connected to each other. Figure 10 and Figure 11 In the common electrode 110 shown, the plurality of second through holes 113 are omitted.

[0088] The radio wave reflecting device 100a applies a control signal to each group of the plurality of patch electrodes 108 arranged in the second direction (Y-axis direction), thereby controlling the reflection direction of the radio wave incident on the reflector 120. Specifically, the radio wave reflecting device 100a can control the direction of the reflected radio wave incident on the reflector 120 to be in the left-right direction in the drawing, centered about a reflection axis RY parallel to the second direction (Y-axis direction).

[0089] Figure 12The diagram schematically illustrates how the direction of travel of the reflected wave changes due to the two reflective elements 102. The diagram shows how, when radio waves enter the first reflective element 102a and the second reflective element 102b with the same phase, the phase change of the reflected wave by the second reflective element 102b is greater than that of the first reflective element 102a due to the application of different control signals (V1≠V2) to the first reflective element 102a and the second reflective element 102b. As a result, the phase of the reflected wave R1 reflected by the first reflective element 102a differs from the phase of the reflected wave R2 reflected by the second reflective element 102b (in the case of the first reflective element 102a). Figure 7 In the example, the phase of the reflected wave R2 is ahead of the phase of the reflected wave R1), and the apparent traveling direction of the reflected wave changes obliquely.

[0090] It should be noted that in Figure 12 In the embodiment, the plurality of patch electrodes 108 arranged in the second direction (Y-axis direction) are electrically connected by the first wiring 118 to the same potential. Therefore, it is also considered to replace the plurality of patch electrodes 108 with a continuous strip-shaped electrode in the second direction (Y-axis direction) rather than a segmented shape. However, since the size of the patch electrodes 108 has an appropriate range depending on the wavelength of the reflected radio wave, a strip-shaped electrode shape would reduce sensitivity to the target wavelength and behave differently for vertically polarized waves and horizontally polarized waves. Therefore, as described above, it is preferable to form the patch electrodes 108 in a symmetrical cross shape for vertically polarized waves and horizontally polarized waves, and to arrange them in an array, with the plurality of patch electrodes 108 arranged parallel to the reflection axis RY connected by the first wiring 118.

[0091] 2-2. Radio wave reflection device B (two-axis reflection control)

[0092] The above-mentioned radio wave reflection device 100a has a single reflection axis RY, and thus can control the reflection angle in a direction with the reflection axis RY as the rotation axis. In contrast, this embodiment shows an example of a radio wave reflection device 100b capable of dual-axis reflection control.

[0093] Figure 13 The structure of the radio wave reflection device 100b of this embodiment is shown. Figure 13 Different parts of the radio wave reflection device 100a shown will be described.

[0094] The radio wave reflection device 100b includes a plurality of first wirings 118 extending in the second direction (Y-axis direction) on the reflector 120, and a plurality of second wirings 132 extending in the first direction (X-axis direction). The plurality of first wirings 118 and the plurality of second wirings 132 are arranged to intersect with each other via an insulating layer (not shown). The plurality of first wirings 118 are connected to the first drive circuit 124, and the plurality of second wirings 132 are connected to the second drive circuit 130. The first drive circuit 124 outputs a control signal, and the second drive circuit 130 outputs a scanning signal.

[0095] Figure 13 An inset diagram showing an enlarged configuration of four patch electrodes 108, two first wirings 118, and a second wiring 132 is shown. Each of the four patch electrodes 108 is provided with a switching element 134. The four patch electrodes 108 are electrically connected to the switching element 134, respectively. The switching (on and off) of the switching element 134 is controlled by a scanning signal applied to the second wiring 132. The patch electrode 108 to which the switching element 134 is turned on is turned on by the first wiring 118 and a control signal is applied. The switching element 134 is formed, for example, by a thin film transistor. According to such a configuration, a plurality of patch electrodes 108 arranged in the first direction or the row direction (X-axis direction) can be selected row by row, and control signals of different voltage levels can be applied to each row. Figure 13 The following example is shown: the patch electrodes 108 are arranged in the first direction or the row direction (X-axis direction) and connected to the second wiring 132 via the switching element 134 provided on each patch electrode 108, the patch electrode 108 is selected by row, and a control signal of a different voltage level is applied to each row.

[0096] Figure 13 The illustrated radio wave reflecting device 100b can control the propagation direction of radio waves reflected from the reflector 120 to the left-right direction in the drawing, with the reflection axis VR being parallel to the second direction (Y-axis direction), and can also control the propagation direction of the reflected waves to the up-down direction in the drawing, with the reflection axis HR being parallel to the first direction (X-axis direction). That is, since the radio wave reflecting device 100b has the reflection axis VR parallel to the second direction (Y-axis direction) and the reflection axis HR parallel to the first direction (X-axis direction), it is possible to control the reflection angle to be in a direction with the reflection axis VR as the rotation axis and in a direction with the reflection axis HR as the rotation axis.

[0097] Figure 14An example of a cross-sectional structure of the reflective element 102 in which the patch electrode 108 is connected to the switching element 134 is shown. The switching element 134 is provided on the first substrate 104. The switching element 134 is a transistor having a structure formed by stacking a first gate electrode 138, a second gate insulating layer 146, a semiconductor layer 142, a second gate insulating layer 146, and a second gate electrode 148. A primer layer 136 may be provided between the first gate electrode 138 and the first substrate 104. A first wiring 118 is provided between the first gate insulating layer 140 and the second gate insulating layer 146. The first wiring 118 is provided 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 in contact with the semiconductor layer 142. The connection structure of the first wiring 118 and the first connection wiring 144 to the semiconductor layer 142 shows a structure in which one wiring is connected to the source of the transistor and the other wiring is connected to the drain.

[0098] A first interlayer insulating layer 150 is provided to cover the switching element 134. A second wiring 132 is provided on the first interlayer insulating layer 150. The second wiring 132 is connected to the second gate electrode 148 via a contact hole formed in the first interlayer insulating layer 150. It should be noted that, 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 in 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.

[0099] A second interlayer insulating layer 154 is provided to cover the second wiring 132 and the second connecting wiring 152. Furthermore, a planarizing layer 156 is provided to fill the step of the switching element 134. The provision of the planarizing layer 156 allows the patch electrode 108 to be formed without affecting the arrangement of the switching element 134. A passivation film 158 is provided on the flat surface of the planarizing layer 156. The patch electrode 108 is provided on the passivation film 158. The patch electrode 108 is connected to the second connecting wiring 152 via a contact hole that penetrates the passivation film 158, the planarizing layer 156, and the second interlayer insulating layer 154. An alignment film 112a is provided on the patch electrode 108.

[0100] and Figure 1 Similarly, the second substrate 106 is provided with a common electrode 110 and an alignment film 112b. The surface of the first substrate 104 provided with the switching element 134 and the patch electrode 108 faces the surface of the second substrate provided with the common electrode 110, with a liquid crystal layer 114 provided between the two surfaces.

[0101] The layers formed on the first substrate 104 are formed using the following materials. The basecoat layer 136 is formed, for example, of a silicon oxide film. The first gate insulating layer 140 and the second gate insulating layer 146 are formed, for example, of a silicon oxide film or a stacked structure of a silicon oxide film and a silicon nitride film. The semiconductor layer is formed of a silicon semiconductor such as amorphous silicon or polycrystalline silicon, or an oxide semiconductor containing a metal oxide such as indium oxide, zinc oxide, or gallium oxide. The first gate electrode 138 and the second gate electrode 148 can also be formed, for example, of molybdenum (Mo), tungsten (W), or an alloy thereof. The first wiring 118, the second wiring 132, the first connecting wiring 144, and the second connecting wiring 152 are formed using metal materials such as titanium (Ti), aluminum (Al), and molybdenum (Mo). For example, they can also be formed using a stacked structure of titanium (Ti) / aluminum (Al) / titanium (Ti) or a stacked structure of molybdenum (Mo) / aluminum (Al) / molybdenum (Mo). The planarization layer 156 is formed of a resin material such as acrylic or polyimide. The passivation film layer 158 is formed of, for example, a silicon nitride film or the like.

[0102] like Figure 14 As shown, by connecting the second wiring 132 to the gate of a transistor serving 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 predetermined patch electrode can be selected from a plurality of patch electrodes 108 arranged in a matrix and a control signal can be applied. Furthermore, by providing the switching element 134 on each patch electrode 108 in the 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 reflector 120 is upright, the reflection direction of the reflected wave can be controlled to the left-right direction or the up-down direction.

[0103] As described above, the radio wave reflecting device 100 according to one embodiment of the present invention includes a plurality of first through-holes 109 in a cross-shaped patch electrode 108 and a plurality of second through-holes 113 in a common electrode 110 that overlaps with the patch electrode 108. The overlapping of the plurality of first through-holes 109 and the plurality of second through-holes 113 ensures a good aesthetic appearance without affecting the appearance, while also exhibiting high reflective properties. Furthermore, the radio wave reflecting device 100 can control the reflection of radio waves in a first direction and a second direction different from the first direction, enabling control of the reflection of 5G radio waves in a desired direction.

[0104] As embodiments of the present invention, the above-mentioned embodiments can be appropriately combined and implemented as long as they are not contradictory to each other. In addition, as long as the gist of the present invention is possessed, the addition, deletion or design change of constituent elements or the addition, omission or condition change of processes appropriately performed by those skilled in the art based on the embodiments are also included in the scope of the present invention.

[0105] Even if there are other effects different from the effects of the above-mentioned embodiments, effects that are known from the description of this specification or easily predicted by those skilled in the art should naturally be regarded as effects brought about by the present invention.

[0106] Description of Reference Numerals

[0107] 100: Radio wave reflecting device, 100a: Radio wave reflecting device, 100b: Radio wave reflecting device, 102: Reflecting element, 102a: First reflecting element, 102b: Second reflecting element, 104: First substrate, 106: Second substrate, 108: Patch electrode, 108-1: First rectangular pattern, 108-2: Second rectangular pattern, 108C: Intersection, 108L1: Straight line portion, 108L2: Straight line portion, 109 : 1st through hole, 109-1: pattern, 109-2: pattern, 109-3: pattern, 109S1: 1st side, 109S2: 2nd side, 110: common electrode, 110-1: pattern, 110-2: pattern, 110C: intersection, 110G1: 1st straight line pattern, 110G2: 2nd straight line pattern, 110L1: straight line portion, 110L2: straight line portion, 111: opening portion, 112a: alignment film, 1 12b: alignment film, 113: second through hole, 113-1: pattern, 113-2: pattern, 113-3: pattern, 113S1: first side, 113S2: second side, 114: liquid crystal layer, 115: intersection, 116: liquid crystal molecules, 117: intersection, 118: first wiring, 120: reflector, 122: peripheral area, 124: first driving circuit, 126: terminal portion, 128: sealing material, 13 0: Second driving circuit, 132: Second wiring, 134: Switching element, 136: Base layer, 138: First gate electrode, 140: First gate insulating layer, 142: Semiconductor layer, 144: First connecting wiring, 146: Second gate insulating layer, 148: Second gate electrode, 150: First interlayer insulating layer, 152: Second connecting wiring, 154: Second interlayer insulating layer, 156: Planarization layer, 158: Passivation film layer.

Claims

1. A radio wave reflection device, characterized in that: include: Patch electrodes; a common electrode opposite to and isolated from the patch electrode; as well as The liquid crystal layer between the patch electrode and the common electrode, The patch electrode has a cross shape when viewed from above, including a first rectangular pattern extending in a first direction and a second rectangular pattern extending in a second direction intersecting the first direction and intersecting the first rectangular pattern. The common electrode has a first stripe pattern extending in the first direction and a second stripe pattern extending in the second direction and intersecting the first stripe pattern when viewed from above. The first rectangular pattern and the second rectangular pattern of the patch electrode overlap with the common electrode. The patch electrode has a plurality of first through holes in the first rectangular pattern and the second rectangular pattern. The common electrode has a second through hole in the first stripe pattern and the second stripe pattern. The first through hole and the second through hole overlap with each other.

2. The radio wave reflection device according to claim 1, wherein: The plurality of first through holes and the plurality of second through holes are rectangular in a plan view and are arranged along the first direction and the second direction.

3. The radio wave reflection device according to claim 2, characterized in that The first through holes are arranged in a plurality of rows in the first rectangular pattern and the second rectangular pattern. The second through holes are arranged in a plurality of rows in the first and second stripe-shaped patterns.

4. The radio wave reflection device according to claim 3, characterized in that The first through holes and the second through holes are arranged in a checkerboard pattern.

5. The radio wave reflection device according to claim 1, wherein: The plurality of first through holes include a slit pattern extending along the first rectangular pattern and the second rectangular pattern, and a dot pattern at an intersection of the first rectangular pattern and the second rectangular pattern. The plurality of second through holes include a slit pattern extending along the first and second stripe patterns, and a dot pattern at an intersection of the first and second stripe patterns.

6. The radio wave reflection device according to claim 5, characterized in that The size of the slit-shaped pattern is different from the size of the dot-shaped pattern.

7. The radio wave reflection device according to claim 1, wherein: The common electrode has a lattice pattern when viewed from above. The common electrode further includes a plurality of intersections where the plurality of first strip-shaped patterns intersect with the plurality of second strip-shaped patterns. The lattice pattern includes a first linear pattern extending along the first direction and a second linear pattern extending along the second direction. The plurality of first straight line patterns and the second band-shaped pattern intersect between a plurality of first intersections among the plurality of intersections. The plurality of second linear patterns intersect the first band-shaped pattern between a plurality of second intersections different from the first intersections.

8. The radio wave reflection device according to claim 1, wherein: The patch electrodes are arranged in a matrix. The patch electrodes are connected in an arrangement in a column direction.

9. The radio wave reflection device according to claim 1, wherein: further comprising a transistor electrically connected to the patch electrode, The transistor is provided on the first substrate. The patch electrode is provided on a second substrate facing the first substrate.

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