Radio wave reflecting device

Abstract

The radio wave reflecting device includes a patch electrode, a common electrode facing and separated from the patch electrode, and a liquid crystal layer between the patch electrode and the common electrode, and the patch electrode and the common electrode have a plurality of openings forming a mesh-like pattern. The ratio (S1 / D) of the opening width (S1) of the opening portion to the interval (D) between the patch electrode and the common electrode is 1.00 or less. In addition, the ratio S1 / D may be 0.10 or less. In addition, the ratio S1 / D may be 0.05 or less. In addition, the plurality of openings of the patch electrode and the plurality of openings of the common electrode may coincide with each other.

Description

Technical Field

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

[0002] A phased array antenna device controls directivity while the antenna is fixed by adjusting the amplitude and phase of the applied high-frequency signal to 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 that utilizes a change in the dielectric constant based on the orientation state of liquid crystal is disclosed (for example, see Patent Document 1). In addition, as an example of a device for reflecting radio waves, a liquid crystal metal reflector that uses the dielectric anisotropy of liquid crystal to change the reflection direction of radio waves 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] 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 fixed dielectric constant reflect a fixed direction of radio waves. 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.

[0008] However, the electrodes of the above-mentioned radio wave reflecting device are made of metal and are opaque, which poses a problem of affecting the view of the place where the radio wave reflecting device is installed.

[0009] In view of the above problems, one of the objectives of one embodiment of the present invention is to provide a radio wave reflecting device that can control the reflection of 5G radio waves in a desired direction without affecting the scenery and has high reflection characteristics.

[0010] An embodiment of the present invention provides an electric wave reflecting device having a patch electrode, a common electrode opposed to and separated from the patch electrode, and a liquid crystal layer between the patch electrode and the common electrode, wherein the patch electrode and the common electrode have a plurality of openings forming a mesh-like pattern, and the ratio S1 / D of the opening width S1 to the interval D between the patch electrode and the common electrode is less than 1.00. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 A plan view showing a reflecting element used in a radio wave reflecting device according to an embodiment of the present invention.

[0012] Figure 2 A cross-sectional view showing a reflecting element used in a radio wave reflecting device according to an embodiment of the present invention.

[0013] Figure 3 A plan view showing a second substrate in the radio wave reflection device according to one embodiment of the present invention.

[0014] Figure 4 A plan view showing a second substrate in the radio wave reflection device according to one embodiment of the present invention.

[0015] Figure 5A 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 no voltage is applied between the patch electrode and the common electrode.

[0016] Figure 5B 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.

[0017] Figure 6 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.

[0018] Figure 7 A plan view showing a radio wave reflecting device according to an embodiment of the present invention.

[0019] Figure 8 The following schematically shows how the traveling direction of a reflected wave is changed by a radio wave reflecting device according to one embodiment of the present invention.

[0020] Figure 9 A plan view showing a radio wave reflecting device according to an embodiment of the present invention.

[0021] Figure 10 A cross-sectional view showing a reflecting element in a radio wave reflecting device according to an embodiment of the present invention.

[0022] Figure 11 The diagram shows the operating state of the reflective element used in the radio wave reflection device, and shows the state in which a voltage is applied between the patch electrode and the common electrode. DETAILED DESCRIPTION

[0023] 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 many different ways and is not limited to the description of the embodiments illustrated below. In order to make the description clearer, the width, thickness, shape, etc. of each part of the accompanying drawings are sometimes schematically shown compared to the actual form, but this is only an example and does not limit the interpretation of the present invention. In addition, in this specification and the drawings, the same elements as those described in the figures above 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 "first" and "second" marked on each element are for the convenience of distinguishing the elements, and do not have other meanings unless otherwise specified.

[0024] In this specification, when a component or area is located "above (or below)" other components or areas, unless otherwise specified, it not only includes the situation where it is located directly above (or below) other components or areas, but also includes the situation where it is located above (or below) other components or areas, that is, it also includes the situation where other components are provided between the above (or below) other components or areas.

[0025] 1. Reflective element

[0026] Figure 1 and Figure 2 A reflecting element 102 used in a radio wave reflecting device according to an embodiment of the present invention is shown. Figure 1 1 shows a top view of the reflective element 102 as viewed from above (radio wave incident side) and an illustration of a portion of the patch electrode 108 magnified. Figure 2 A cross-sectional view taken along line A1 - A2 shown in the top view is shown.

[0027] like Figure 1 and Figure 2 As 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. In the reflective element 102, the first substrate 104, with the patch electrode 108, is positioned 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 positioned opposite and spaced apart from each other. The common electrode 110 is positioned on the back side of the patch electrode 108. The liquid crystal layer 114 is positioned 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 .

[0028] The patch electrode 108 preferably has a shape that is symmetrical with respect to the vertically polarized wave and the horizontally polarized wave of the incident radio wave, for example, a polygonal or circular shape in a plan view. Figure 1 The patch electrode 108 is shown as a quadrilateral, particularly a square, when viewed from above.

[0029] The patch electrode 108 has a plurality of openings 109 forming a mesh pattern. The plurality of openings 109 may be arranged at equal intervals within the surface of the patch electrode 108. Figure 1 As shown in the illustration, if the width of the opening 109 of the patch electrode 108 is set to S1 and the interval between adjacent openings is set to L1, L1 can be smaller than S1 or equal to S1. Relatively speaking, by increasing S1 and reducing L1, the light transmittance (transparency) of the patch electrode 108 can be improved, and by increasing L1, the orientation control of the liquid crystal layer 114 can be reliably performed. As described later, the sizes of S1 and L1 are determined by balancing the light transmittance (transparency) of the patch electrode 108 and the orientation control of the liquid crystal. The shapes of the multiple openings 109 are not limited, as shown in FIG. Figure 1 As shown, the openings 109 may be a quadrilateral, a polygon such as a hexagon, or a circle. In addition, the plurality of openings 109 may be a mixture of squares such as a quadrilateral and circles.

[0030] The common electrode 110 also has a plurality of openings 111 (see Figure 4 The plurality of openings 111 preferably have the same pattern and size as the plurality of openings 109 provided in the patch electrode 108. Furthermore, the plurality of openings 111 provided in the common electrode 110 and the plurality of openings 109 provided in the patch electrode 108 preferably overlap when viewed from above. This arrangement can improve the light transmittance (transparency) of the reflective element 102.

[0031] In addition to imparting light transmittance (transparency) to the patch electrode 108, the multiple openings 109 provided in the patch electrode 108 also have the function of orienting the liquid crystal in the openings using the fringe field. Therefore, the opening width S1 of the multiple openings 109 is determined by the thickness of the liquid crystal layer 114, that is, the relationship between the interval D between the patch electrode 108 and the common electrode 110. From the perspective of controlling the orientation of the liquid crystal, it is preferred that the opening width S1 is the same as or less than the interval D between the patch electrode 108 and the common electrode 110. Specifically, the ratio S1 / D of the opening width S1 to the interval D between the patch electrode 108 and the common electrode 110 may also be greater than 0.1 and less than 1.00. When the ratio S1 / D of the opening width S1 to the interval D between the patch electrode 108 and the common electrode 110 is greater than 0.1 and less than 1.00, on the basis of the parallel electric field formed when a voltage is applied between the patch electrode 108 and the common electrode 110, the fringe field formed at the opening ends of the multiple openings 109 can also be used to align the liquid crystal molecules of the entire liquid crystal layer 114 between the patch electrode 108 and the common electrode 110.

[0032] Furthermore, the ratio S1 / D of the opening width S1 to the distance D between the patch electrode 108 and the common electrode 110 may be 0.05 or more and 0.10 or less. When the ratio S1 / D of the opening width S1 to the distance D between the patch electrode 108 and the common electrode 110 is 0.05 or more and 0.10 or less, the liquid crystal molecules in the liquid crystal layer 114 can be more effectively aligned by utilizing the fringe field formed at the opening ends of the plurality of openings 109 when a voltage is applied between the patch electrode 108 and the common electrode 110.

[0033] Furthermore, the ratio S1 / D of the opening width S1 to the distance D between the patch electrode 108 and the common electrode 110 can be set to 0.03 or more and 0.05 or less. When the ratio S1 / D of the opening width S1 to the distance D between the patch electrode 108 and the common electrode 110 is 0.03 or more and 0.05 or less, the liquid crystal molecules in the liquid crystal layer 114 can be more effectively aligned using the electric field formed when a voltage is applied between the patch electrode 108 and the common electrode 110. If the total area of ​​the plurality of openings 109 arranged in one patch electrode 108 is maintained at approximately 2 to 1 relative to the area of ​​one patch electrode 108, the ratio S1 / D of the opening width S1 to the distance D between the patch electrode 108 and the common electrode 110 can be even smaller. In other words, if the ratio of the total area of ​​the plurality of openings 109 arranged on one patch electrode 108 to the area of ​​one patch electrode 108 is maintained at approximately 2:1, more openings 10 can be provided on the patch electrode 108 .

[0034] The interval D represents the distance between the patch electrode 108 and the common electrode 110. Specifically, Figure 2 As shown, the distance between the end of the patch electrode 108 facing the second substrate 106 and the end of the common electrode 110 facing the first substrate 104 can be set. The interval D can be set to 30 to 50 μm. Alternatively, the interval D can be set to 10 to 50 μm, for example, a distance of 50 μm. The interval D is substantially set to the thickness of the liquid crystal layer 114. It should be noted that the film thicknesses of the patch electrode 108, the common electrode 110, the orientation film 112a, and the orientation film 112b are sufficiently smaller than the thickness of the liquid crystal layer 114, so the distance between the first substrate 104 and the second substrate 106 can also be set to the interval D.

[0035] Here, see Figure 3 and Figure 4 , the second substrate 106 on which the common electrode 110 is formed will be described. Figure 3 A plan view showing a second substrate in the radio wave reflection device according to one embodiment of the present invention. Figure 4 A plan view showing a second substrate in the radio wave reflection device according to one embodiment of the present invention.

[0036] The common electrode 110 has a shape extending over substantially the entire surface of the second substrate 106 so as to have a larger area than the patch electrode 108 (see FIG. Figure 7 ) In addition, the common electrode 110 can be arranged in a region surrounded by a sealing material 128 described later.

[0037] like Figure 3 As shown, the common electrode 110 has a plurality of opening patterns 119 corresponding to the patch electrodes 108. The opening patterns 119 are arranged in a matrix on the second substrate 106.

[0038] Figure 4 The figure shows an enlarged top view of the opening pattern 119 and an enlarged illustration of the six openings 111. Figure 4 As shown, the opening pattern 119 has a plurality of openings 111 forming a mesh-like pattern. The plurality of openings 111 can be arranged at equal intervals in the opening pattern 119. The intervals L2 between adjacent openings 111 can be set to be equal or approximately equal. In addition, the areas of the plurality of openings 111 can be set to be equal or approximately equal. In addition, the shapes of the plurality of openings 111 can be set to be equal or approximately equal. The shape of the opening 111 can have a polygonal or circular shape. Figure 4 As shown, when the shape of the opening 111 is a square, it is easy to make the intervals between adjacent openings 111 equal.

[0039] When the opening 111 is a square, Figure 4As shown, the opening width S2 is equivalent to the length of one side when viewed from above. In addition, when the shape of the opening 111 is circular, the opening width S2 is equivalent to the diameter of the circle when viewed from above.

[0040] Here again, refer to Figure 2 The opening 111 and the opening width S2 will be described.

[0041] The opening 111 is arranged to overlap with the opening 109 of the patch electrode 108. Figure 2 As shown, the arrangement is such that visible light entering from the first substrate 104 passes through opening 109, and the same visible light passes through opening 111. Furthermore, patch electrodes 108 corresponding to the spacing L1 between adjacent openings 109 and common electrodes 110 corresponding to the spacing L2 between adjacent openings 111 are arranged to overlap. The opening width S2 is equal to or substantially equal to the opening width S1. The spacing L1 is equal to or substantially equal to the spacing L2.

[0042] The opening width S2 can be defined in the same manner as the opening width S1 of the opening portion 109 of the patch electrode 108. The opening width S2 is the same as or less than the interval D between the patch electrode 108 and the common electrode 110. Specifically, the ratio S2 / D of the opening width S2 to the interval D between the patch electrode 108 and the common electrode 110 is greater than 0.1 and less than 1.00. When the ratio S2 / D of the opening width S2 to the interval D between the patch electrode 108 and the common electrode 110 is greater than 0.1 and less than 1.00, the liquid crystal molecules of the liquid crystal layer 114 located between the opening portion 109 and the opening portion 111 can move. Specifically, when a voltage is applied between the patch electrode 108 and the common electrode 110, due to, for example Figure 2 The patch electrode 108-1 shown is close to the patch electrode 108-2, so an electric field is formed between the patch electrode 108-1 and the common electrode 110-2 overlapping with the patch electrode 108-2, which can control the orientation state of the liquid crystal molecules in the liquid crystal layer 114-1 located between the opening 109-1 and the opening 111-1.

[0043] The ratio S2 / D of the opening width S2 to the distance D between the patch electrode 108 and the common electrode 110 can be set to 0.05 or more and 0.10 or less. By setting the ratio S2 / D to be smaller, the opening width S2 is reduced, for example Figure 2The distance between patch electrode 108-1 and common electrode 110-2 is shown to be smaller. Therefore, when a voltage is applied between patch electrode 108 and common electrode 110, a stronger electric field is formed between patch electrode 108-1 and common electrode 110-2, which overlaps with patch electrode 108-2. This can control the alignment of liquid crystal molecules in liquid crystal layer 114-1 between openings 109-1 and 111-1.

[0044] Furthermore, the ratio S2 / D of the opening width S2 relative to the distance D between the patch electrode 108 and the common electrode 110 may be set to be greater than or equal to 0.03 and less than or equal to 0.05. By setting the ratio S2 / D to be smaller, the opening width S2 is reduced. Therefore, when a voltage is applied between the patch electrode 108 and the common electrode 110, the electric field formed between the patch electrode 108-1 and the common electrode 110-2 can control the alignment of the liquid crystal molecules in the liquid crystal layer 114-1 located between the opening 109-1 and the opening 111-1.

[0045] The patch electrode 108 having the opening 109 and the common electrode 110 having the opening 111 can be made of a material that reflects visible light. Furthermore, a metal material with low specific resistance can be used to form the patch electrode 108 and the common electrode 110. For example, a metal film such as aluminum (Al) or copper (Cu) can be used to form the patch electrode 108 and the common electrode 110.

[0046] Next, the main structures of the first substrate 104 provided with the patch electrodes 108 and the second substrate 106 provided with the common electrodes 110 will be described.

[0047] The first substrate 104 and the second substrate 106 are bonded together by a sealing material to be described later (see Figure 7 ). The first substrate 104 and the second substrate 106 are arranged opposite 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 to 100 μm, for example, a gap of 50 μm. This gap also includes the gap D between the patch electrode 108 and the common electrode 110 mentioned above. 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 the first substrate 104 and the second substrate 106 respectively becomes the thickness of the liquid crystal layer 114. It should be noted that, Figure 2 Although not shown in the figure, a spacer for maintaining a constant distance between the first substrate 104 and the second substrate 106 may be provided.

[0048] A control signal for controlling the orientation 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 signal or a polarity reversal signal in which a positive DC voltage and a negative DC voltage are alternately reversed. The common electrode 110 is applied with a voltage of an intermediate level of the ground or polarity reversal signal. By applying the control signal to the patch electrode 108, the orientation state of the liquid crystal molecules contained in the liquid crystal layer 114 changes. The 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 the liquid crystal layer 114. The dielectric constant of the liquid crystal layer 114 with dielectric anisotropy changes according to the change in the orientation state of the liquid crystal molecules. The reflective element 102 can change the dielectric constant of the liquid crystal layer 114 by applying the control signal to the patch electrode 108, thereby delaying the phase of the reflected wave when reflecting the radio wave.

[0049] 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 millimeter wave (EHF) band. The liquid crystal molecules in liquid crystal layer 114 change their orientation in response to a control signal applied to patch electrode 108. However, these liquid crystal molecules rarely follow the frequency of the radio waves directed at patch electrode 108. Therefore, reflective element 102 can control the phase of the reflected radio waves without being affected by the radio waves.

[0050] Next, refer to Figure 5A and Figure 5B 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.

[0051] Figure 5A A 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 5A 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 5BThe 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 acted upon by an electric field, aligning their long axes perpendicular to the surfaces of patch electrode 108 and common electrode 110. The angle of the long axis of liquid crystal molecules 116 can be adjusted to an intermediate position between horizontal and vertical directions 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).

[0052] 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 less 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 by utilizing the dielectric anisotropy of the liquid crystal layer 114 to achieve phase delay (or no delay) in the reflected wave.

[0053] Here, refer to Figure 6 The alignment state of the liquid crystal layer 114 in the reflective element 102 in which the patch electrode 108 and the common electrode 110 have the opening 109 and the opening 111 whose opening widths satisfy the above-mentioned ratio S1 / D will be described.

[0054] Figure 6 The state in which a voltage for controlling the orientation state of the liquid crystal is applied between the patch electrode 108 and the common electrode 110 is shown. Figure 6 The distance D between the patch electrode 108 and the common electrode 110 of the reflective element 102 shown, and the opening width S1 of the opening 109 satisfy the aforementioned ratio S1 / D. Furthermore, the opening width S2 of the opening 111 also satisfies the aforementioned ratio S1 / D relative to the distance D between the patch electrode 108 and the common electrode 110 of the reflective element 102.

[0055] The liquid crystal layer 114 of the reflective element 102 is as follows Figure 6 As shown, there is a liquid crystal layer 114x showing the state of liquid crystal molecules oriented between the patch electrode 108 and the common electrode 110. The liquid crystal layer 114x showing the state of liquid crystal molecules oriented, for example, Figure 5B The liquid crystal layer 114y is not between the patch electrode 108 and the common electrode 110, so it is shown as follows: Figure 5A The state of the liquid crystal molecules 116 is shown (non-operating state).

[0056] Reflective element 102 allows visible light to pass because patch electrode 108 and common electrode 110 overlap with their respective openings 109 and 111. Furthermore, the opening widths S1 and S2 of opening 109 and 111 satisfy the aforementioned ratio S1 / D relative to the spacing D between patch electrode 108 and common electrode 110. This allows the liquid crystal molecules in the liquid crystal layer between openings 109 and 111 to move, and thus the liquid crystal molecules throughout liquid crystal layer 114 between patch electrode 108 and common electrode 110 to move.

[0057] Next, refer to Figure 11 The alignment state of the liquid crystal layer 914 in the reflective element 902 will be described. The reflective element 902 has an opening 909 and an opening 911 whose widths are different from the opening width S1 and the opening width S2 of the reflective element 102 .

[0058] Figure 11 The state in which a voltage for controlling the orientation state of the liquid crystal is applied between the patch electrode 908 and the common electrode 910 is shown. The opening width S91 of the opening 909 is greater than Figure 11 The distance D9 between the patch electrode 908 and the common electrode 910 of the reflective element 902 is shown. In addition, the opening width S92 of the opening 911 is also larger than the distance D9 between the patch electrode 908 and the common electrode of the reflective element 902.

[0059] like Figure 11 As shown, the liquid crystal layer 914 of the reflective element 902 includes a liquid crystal layer 914x showing the state of liquid crystal molecule orientation between the patch electrode 908 excluding the opening 909 and the common electrode 910 excluding the opening 911. The liquid crystal layer 914y is provided between the opening 909 of the patch electrode 908 and the opening 911 of the common electrode 910. Although the liquid crystal layer 914y shows Figure 5B The illustrated state is a state in which a voltage is applied to the patch electrode 108 and the common electrode 110 but the alignment is insufficient compared to the liquid crystal molecules 116 of the liquid crystal layer 114 x , or a state in which the liquid crystal molecules 116 are not aligned.

[0060] According to this embodiment, patch electrode 108 is provided with a plurality of openings 109, and common electrode 110 is provided with a plurality of openings 111. These openings 109 and 111 are arranged so as to overlap, thereby allowing visible light entering from first substrate 104 and second substrate 106 to pass through. Consequently, patch electrode 108 and common electrode 110 of radio wave reflection device 100 are transparent and blend in with the landscape.

[0061] Furthermore, according to this embodiment, the opening width S1 of the opening 109 of the patch electrode 108 and the opening width S2 of the opening 111 of the common electrode 110 satisfy the aforementioned ratio S1 / D (and S2 / D). This allows the radio wave reflecting device 100 to be transparent and generate an electric field across the entire liquid crystal layer 114 between the patch electrode 108 and the common electrode 110, thereby causing the liquid crystal molecules throughout the liquid crystal layer 114 to operate. Consequently, the radio wave reflecting device 100 can exhibit high reflection characteristics for radio waves incident on the device 100.

[0062] 2. Radio wave reflection device

[0063] Next, the configuration of a radio wave reflecting device in which the reflecting elements 102 are integrated will be described.

[0064] 2-1. Radio wave reflection device A (single-axis reflection control)

[0065] Figure 7 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 7 The X-axis direction shown in FIG) and the second direction intersecting the first direction ( Figure 7 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.

[0066] The radio wave reflection device 100a has a structure in which a plurality of reflection elements 102 are integrated on a first substrate 104. Figure 7 As shown, the radio wave reflection device 100a has a structure in which a first substrate 104 on which a plurality of patch electrodes 108 are arranged is overlapped 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 and the common electrode 110 overlap. 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 2 The structure of the reflective element 102 shown is the same. The first substrate 104 and the second substrate 106 are bonded together using a sealant 128 , and a liquid crystal layer (not shown) is provided in a region inside the sealant 128 .

[0067] In addition to the area facing the second substrate 106, the first substrate 104 also includes a peripheral area 122 extending 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 control signals to the patch electrodes 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.

[0068] As described above, on the first substrate 104, a plurality of patch electrodes 108 are arranged in the first direction (X-axis direction) and the second direction (Y-axis direction). 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 each electrically connected to the plurality of patch electrodes 108 arranged in the second direction (Y-axis direction). 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 the following structure: a column of patch electrode arrays connected by the first wirings 118 is arranged in the first direction (X-axis direction). In Figure 7 , an example is shown in which the patch electrodes 108 are connected in each column in the column direction (Y-axis direction).

[0069] A plurality of first wirings arranged on the reflector 120 extend through 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 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).

[0070] 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 direction of reflection of radio waves incident on the reflector 120. Specifically, the radio wave reflecting device 100a can control the direction of reflection of radio waves incident on the reflector 120 to the left and right in the figure, centered about a reflection axis RY parallel to the second direction (Y-axis direction).

[0071] Figure 8The following diagram schematically illustrates how the direction of travel of the reflected wave is changed by the two reflective elements 102. The diagram shows a situation where, when radio waves are incident on the first reflective element 102a and the second reflective element 102b with the same phase, different control signals (V1≠V2) are applied to the first reflective element 102a and the second reflective element 102b, resulting in a larger phase change in the reflected wave from the second reflective element 102b than from the first reflective element 102a. 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 8 (In the figure, the phase of the reflected wave R2 is ahead of the phase of the reflected wave R1), and it seems that the traveling direction of the reflected wave changes obliquely.

[0072] It should be noted that in Figure 7 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 and are electrically at the same potential. Therefore, it is also possible to consider replacing the patch electrodes 108 with strips that are continuous in the second direction (Y-axis direction) rather than being divided into multiple shapes. However, the size of the patch electrodes 108 has an appropriate range depending on the wavelength of the reflected radio wave. Therefore, if the patch electrodes are in the shape of strips, the sensitivity to the target wavelength is reduced, and the behavior with respect to vertically polarized waves and horizontally polarized waves is different. Therefore, if the patch electrodes 108 are in the shape of strips, the sensitivity to the target wavelength is reduced, and the behavior with respect to vertically polarized waves and horizontally polarized waves is different. Figure 7 As shown, the patch electrode 108 is preferably configured to be symmetrical with respect to vertically polarized waves and horizontally polarized waves ( Figure 7 A square is shown, but a circle may be used. The plurality of patch electrodes 108 are arranged in an array and are connected by first wiring 118 and are aligned parallel to the reflection axis RY.

[0073] 2-2. Radio wave reflection device B (dual-axis reflection control)

[0074] The above-mentioned radio wave reflection device 100a has a single reflection axis RY, and therefore 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.

[0075] Figure 9 The structure of the radio wave reflection device 100b of this embodiment is shown in FIG. Figure 7 The description will focus on the different parts of the radio wave reflection device 100a shown.

[0076] In addition to the plurality of first wirings 118 extending in the second direction (Y-axis direction) on the reflector 120, the radio wave reflection device 100b also includes 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.

[0077] Figure 9 An illustration 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. Each of the four patch electrodes 108 is electrically connected to the switching element 134. The switching (on and off) of the switching element 134 is controlled by a scanning signal applied to the second wiring 132. The patch electrode 108 with the switching element 134 turned on is conductive with the first wiring 118 and a control signal is applied thereto. 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 (X-axis direction) are selected by row, and control signals of different levels can be applied to each row. In Figure 9 The following example is shown: each arrangement of patch electrodes 108 in the row direction (X-axis direction) is connected to the second wiring 132 via a switching element 134 provided in each patch electrode 108, the patch electrodes 108 are selected by row, and control signals of different levels are applied to each row.

[0078] Figure 9 The illustrated radio wave reflecting device 100b can control the propagation direction of radio waves incident on the reflector 120 not only in the horizontal direction in the figure, with a reflection axis VR parallel to the second direction (Y-axis direction) as the center, but also in the vertical direction in the figure, with a reflection axis HR parallel to the first direction (X-axis direction) as the center. That is, the radio wave reflecting device 100b has a reflection axis VR parallel to the second direction (Y-axis direction) and a reflection axis VH parallel to the first direction (X-axis direction), and thus can control the reflection angle 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.

[0079] Figure 10An example of a cross-sectional structure of a reflective element 102 in which a patch electrode 108 is connected to a 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 stacked structure of 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 between the first wiring 118 and the first connection wiring 144 and 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.

[0080] 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.

[0081] 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 being affected by the placement 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.

[0082] The second substrate 106 and Figure 2 The surface of the first substrate 104 on which the switching element 134 and the patch electrode 108 are provided faces the surface of the second substrate on which the common electrode 110 is provided, with the liquid crystal layer 114 provided between the two surfaces.

[0083] 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 including 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 a metal material such as titanium (Ti), aluminum (Al), or 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.

[0084] like Figure 10 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 in each patch electrode 108 on 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 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.

[0085] As described above, the radio wave reflecting device 100 according to one embodiment of the present invention includes an opening 109 in the patch electrode 108 and an opening 111 in the common electrode 110 that overlaps with the opening 109. By making the opening width S1 of the opening 109 and the opening width S2 of the opening 111 smaller than the distance D between the patch electrode 108 and the common electrode 110, high reflection characteristics can be achieved without affecting the visual appearance. Furthermore, the radio wave reflecting device 100 can control the reflection of radio waves in both the row and column directions, enabling controlled reflection of 5G radio waves in a desired direction.

[0086] 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 methods obtained by those skilled in the art by appropriately adding, deleting or changing the design of the constituent elements or adding, omitting or changing the conditions of the processes based on the embodiments are all included in the scope of the present invention.

[0087] Even if there are other effects different from the effects brought about by the above-mentioned embodiments, effects that are known from the description of this specification or easily predicted by those skilled in the art should of course be regarded as brought about by the present invention.

[0088] Description of Reference Numerals

[0089] 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: Patch electrode, 108-2: Patch electrode, 109: Opening, 109-1: Opening, 110: Common electrode, 110-1: Metal layer, 110-2: Common electrode, 111: Opening, 111-1: Opening, 112a: Alignment film, 112b: Alignment film, 114: Liquid crystal layer, 114-1: Liquid crystal layer, 114x: Liquid crystal layer, 114y: Liquid crystal layer, 116: Liquid crystal molecules, 118: First wiring, 119: Opening pattern, 120: Reflecting plate, 122: Peripheral area, 124: 1st driving circuit, 126: terminal part, 128: sealing material, 130: 2nd driving circuit, 132: 2nd wiring, 134: switching element, 136: primer layer, 138: 1st gate electrode, 140: 1st gate insulating layer, 142: semiconductor layer, 144: 1st connecting wiring, 146: 2nd gate insulating layer, 148: 2nd gate electrode, 150: 1st interlayer insulating layer, 152: 2nd connecting wiring, 154: 2nd interlayer insulating layer, 156: planarization layer, 158: passivation film layer, 902: reflecting element, 908: patch electrode, 909: opening part, 910: common electrode, 911: opening part, 912a: orientation film, 912b: orientation film, 914: liquid crystal layer, 914x: liquid crystal layer, 914y: liquid crystal layer.

Claims

1. A radio wave reflection device comprising: Patch electrodes; a common electrode opposite to and separated from the patch electrode; and The liquid crystal layer between the patch electrode and the common electrode, The patch electrode and the common electrode have a plurality of openings forming a mesh pattern. A ratio S1 / D of an opening width S1 of the opening portion to a distance D between the patch electrode and the common electrode is equal to or less than 1.

00.

2. The radio wave reflection device according to claim 1, wherein: The ratio S1 / D is 0.10 or less.

3. The radio wave reflection device according to claim 2, wherein: The ratio S1 / D is 0.05 or less.

4. The radio wave reflection device according to claim 1, wherein: The plurality of openings of the patch electrode overlap with the plurality of openings of the common electrode.

5. The radio wave reflection device according to claim 1, wherein: The patch electrode is arranged on the incident surface side of the radio wave, and the common electrode is arranged on the back surface side of the patch electrode.

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

7. 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.

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