Radio wave reflector

Abstract

The present invention provides a radio wave reflecting plate which has excellent reflection characteristics.　This radio wave reflecting plate is provided with a first substrate, a second substrate, a sealing material, a liquid crystal layer and a radio wave absorber. The first substrate comprises: a first base material that is positioned in a first region and a second region; and a plurality of patch electrodes. The second substrate comprises a second base material and a common electrode. The radio wave absorber is positioned in the second region.

Description

[Technical Field]

[0001] An embodiment of the present invention relates to a radio wave reflector. [Background technology]

[0002] Phase shifters using liquid crystals are being developed for use in phased array antennas, which can electrically control directivity. In phased array antennas, multiple antenna elements to which high-frequency signals are transmitted from corresponding phase shifters are arranged one-dimensionally (or two-dimensionally). In such phased array antennas, the dielectric constant of the liquid crystal needs to be adjusted so that the phase difference between the high-frequency signals input to adjacent antenna elements is constant.

[0003] In addition, research is also being conducted into radio wave reflectors that can control the direction of radio wave reflection using liquid crystals, similar to phased array antennas. In these radio wave reflectors, reflection control sections with reflective electrodes are arranged one-dimensionally (or two-dimensionally). In radio wave reflectors, too, it is necessary to adjust the dielectric constant of the liquid crystal so that the phase difference of the reflected radio waves is constant between adjacent reflection control sections. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 11-103201 [Patent Document 2] Special Publication No. 2019-530387 Summary of the Invention [Problem to be solved by the invention]

[0005] This embodiment provides a radio wave reflector with excellent reflection characteristics. [Means for solving the problem]

[0006] The radio wave reflector according to one embodiment includes: a first substrate having a first main surface and a second main surface opposite to the first main surface, the first substrate being located in a first region and a second region outside the first region, and a plurality of patch electrodes located in the first region, facing the first main surface, and arranged in a matrix at intervals along an X-axis and a Y-axis perpendicular to each other; a second substrate including: a second base material located in the first region and the second region, the second base material having a third main surface facing the first main surface and a fourth main surface opposite the third main surface; and a common electrode located in the first region, provided between the first substrate and the third main surface, and facing the plurality of patch electrodes in a direction parallel to a Z axis that is orthogonal to each of the X axis and the Y axis; a sealant located in the second region and joining the first substrate and the second substrate; a liquid crystal layer held between the first substrate and the second substrate and surrounded by the sealing material; and a radio wave absorber located in the second region. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a cross-sectional view showing a radio wave reflector according to a first embodiment. [Figure 2] FIG. 2 is a plan view showing the radio wave reflector shown in FIG. [Figure 3] FIG. 3 is an enlarged cross-sectional view showing a part of the radio wave reflector. [Figure 4] FIG. 4 is an enlarged plan view showing the patch electrode. [Figure 5] FIG. 5 is an enlarged cross-sectional view showing a part of the radio wave reflector, and shows a single reflection control section. [Figure 6] FIG. 6 is an enlarged cross-sectional view showing a part of the radio wave reflector, and shows a plurality of reflection control sections. [Figure 7] FIG. 7 is a timing chart showing the change in voltage applied to the patch electrode for each period in the method for driving the radio wave reflector of the first embodiment. [Figure 8] FIG. 8 is a cross-sectional view showing a radio wave reflector according to a first example of the first embodiment. [Figure 9] FIG. 9 is a cross-sectional view showing a radio wave reflector according to a second example of the first embodiment. [Figure 10] FIG. 10 is a cross-sectional view showing a radio wave reflector according to a third example of the first embodiment. [Figure 11] FIG. 11 is an enlarged cross-sectional view showing a part of a radio wave reflector according to a third example of the first embodiment, and is a diagram for explaining a first means for fixing the potential of the first conductive layer. [Figure 12] FIG. 12 is an enlarged cross-sectional view showing a part of a radio wave reflector and a cable according to a third example of the first embodiment, and is a diagram for explaining a second means for fixing the potential of the first conductive layer. [Figure 13] FIG. 13 is a cross-sectional view showing a radio wave reflector according to a first example of the second embodiment. [Figure 14] FIG. 14 is an enlarged cross-sectional view showing a part of the radio wave reflector of the first example of the second embodiment, showing a plurality of patch electrodes, a plurality of frequency selective plates, and a sealing material. [Figure 15] FIG. 15 is an enlarged cross-sectional view showing a first modified example of the plurality of frequency selective surfaces, illustrating a plurality of patch electrodes and a plurality of frequency selective surfaces. [Figure 16] FIG. 16 is an enlarged cross-sectional view showing a second modified example of the plurality of frequency selective surfaces, illustrating a plurality of patch electrodes and a plurality of frequency selective surfaces. [Figure 17] FIG. 17 is an enlarged cross-sectional view showing a third modified example of the plurality of frequency selective surfaces, illustrating a plurality of patch electrodes and a plurality of frequency selective surfaces. [Figure 18] FIG. 18 is a cross-sectional view showing a radio wave reflector according to a second example of the second embodiment. [Figure 19] FIG. 19 is a cross-sectional view showing a radio wave reflector according to a third example of the second embodiment. [Figure 20] FIG. 20 is a cross-sectional view showing a radio wave reflector according to a first example of the third embodiment. [Figure 21]FIG. 21 is a cross-sectional view showing a radio wave reflector according to a second example of the third embodiment. [Figure 22] FIG. 22 is a plan view showing a radio wave reflector according to the fourth embodiment. [Figure 23] FIG. 23 is a perspective view showing the reflecting device according to the fourth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, each embodiment of the present invention will be described with reference to the drawings. The disclosure is merely an example, and appropriate modifications that a person skilled in the art can easily conceive while maintaining the gist of the invention are naturally included within the scope of the present invention. Furthermore, in order to clarify the explanation, the drawings may show the width, thickness, shape, etc. of each part schematically compared to the actual embodiment, but these are merely examples and are not intended to limit the interpretation of the present invention. Furthermore, in this specification and each drawing, elements similar to those described above with reference to the previous drawings will be designated by the same reference numerals, and detailed descriptions may be omitted as appropriate.

[0009] (First embodiment) First, a first embodiment will be described. Fig. 1 is a cross-sectional view showing a radio wave reflector RE according to this embodiment. The radio wave reflector RE can reflect radio waves and functions as a relay device for radio waves.

[0010] As shown in Fig. 1, the radio wave reflector RE includes a first substrate SUB1, a second substrate SUB2, and a liquid crystal layer LC. The first substrate SUB1 includes an electrically insulating base material 1, a plurality of patch electrodes PE, and an alignment film AL1. The base material 1 serving as the first base material is formed in a flat plate shape and extends along an XY plane including an X-axis and a Y-axis that are orthogonal to each other. The alignment film AL1 covers the plurality of patch electrodes PE.

[0011] The second substrate SUB2 is disposed opposite the first substrate SUB1 with a predetermined gap therebetween. The second substrate SUB2 has an electrically insulating base material 2, a common electrode CE, and an alignment film AL2. The base material 2 serving as the second base material is formed in a flat plate shape and extends along the XY plane. The base material 1 and the base material 2 are made of glass. However, the base material 1 and the base material 2 may be made of an insulating material other than glass, such as resin.

[0012] The common electrode CE faces the multiple patch electrodes PE in a direction parallel to the Z axis, which is orthogonal to both the X axis and the Y axis. The multiple patch electrodes PE, the common electrode CE, etc. are located in a reflective area RA. An alignment film AL2 covers the common electrode CE. In this embodiment, the alignment films AL1 and AL2 are both horizontal alignment films.

[0013] The first substrate SUB1 and the second substrate SUB2 are joined together by a sealant SE disposed on their respective peripheral edges. The sealant SE is located in a non-reflective area NRA outside the reflective area RA. The liquid crystal layer LC is provided in a space surrounded by the first substrate SUB1, the second substrate SUB2, and the sealant SE. The liquid crystal layer LC is held between the first substrate SUB1 and the second substrate SUB2. The liquid crystal layer LC faces a plurality of patch electrodes PE on one side and a common electrode CE on the other side.

[0014] Here, the thickness of the liquid crystal layer LC (cell gap) is d l The thickness d l is larger than the thickness of the liquid crystal layer of a normal liquid crystal display panel, and is, for example, about 5 to 20 times the thickness of a normal liquid crystal display device. l However, if the reflection phase of the radio wave can be adjusted sufficiently, the thickness d l Alternatively, the thickness d may be less than 50 μm in order to increase the reflection angle of the radio wave. l The thickness may exceed 50 μm. The liquid crystal material used in the liquid crystal layer LC of the radio wave reflector RE is different from the liquid crystal material used in ordinary liquid crystal display panels. The reflection phase of the radio wave mentioned above will be described later.

[0015] A common voltage is applied to the common electrode CE, and the potential of the common electrode CE is fixed. In this embodiment, the common voltage is 0 V. A voltage is also applied to the patch electrode PE. In this embodiment, the patch electrode PE is driven by an AC current. The liquid crystal layer LC is driven by a so-called vertical electric field. The voltage applied between the patch electrode PE and the common electrode CE acts on the liquid crystal layer LC, changing the dielectric constant of the liquid crystal layer LC.

[0016] When the dielectric constant of the liquid crystal layer LC changes, the propagation speed of the radio waves in the liquid crystal layer LC also changes. Therefore, by adjusting the voltage applied to the liquid crystal layer LC, the reflection phase of the radio waves can be adjusted. Ultimately, the reflection direction of the radio waves can be adjusted. In this embodiment, the absolute value of the voltage applied to the liquid crystal layer LC is 10 V or less. This is because the dielectric constant of the liquid crystal layer LC becomes saturated at 10 V. However, the absolute value of the voltage applied to the liquid crystal layer LC may exceed 10 V. For example, if an improvement in the response speed of the liquid crystal is required, a voltage exceeding 10 V may be applied to the liquid crystal layer LC, and then a voltage of 10 V or less may be applied to the liquid crystal layer LC. The first substrate SUB1 has an incident surface Sa on the side opposite to the side facing the second substrate SUB2. In the figure, an incident wave w1 is a radio wave incident on the radio wave reflector RE, and a reflected wave w2 is a radio wave reflected by the radio wave reflector RE.

[0017] Fig. 2 is a plan view showing the radio wave reflector RE shown in Fig. 1. In the drawing, a dot pattern is applied to the sealing material SE. 2, the patch electrodes PE are arranged in a matrix at intervals along both the X and Y axes. In the XY plane, the patch electrodes PE have the same shape and size.

[0018] The plurality of patch electrodes PE are located in the reflective area RA and are arranged at equal intervals along the X axis and at equal intervals along the Y axis. The first substrate SUB1 has a plurality of signal lines SL, a plurality of control lines GL, a plurality of switching elements SW, a drive circuit DR, and a plurality of lead wires LE.

[0019] A driving circuit DC is mounted on the first substrate SUB1 in an area that does not face the second substrate SUB2. The driving circuit DC is composed of an integrated circuit. The driving circuit DC is connected to outer lead bonding (OLB) pads p.

[0020] A plurality of signal wirings SL extend along the Y-axis and are arranged in a direction along the X-axis. The signal wirings SL are connected to a drive circuit DC. A plurality of control wirings GL extend along the X-axis and are arranged in a direction along the Y-axis. The signal wirings SL and control wirings GL extend in the reflective area RA and the non-reflective area NRA. The drive circuit DR is located in the non-reflective area NRA. The plurality of control wirings GL are connected to the drive circuit DR.

[0021] The switching element SW is provided near the intersection of one signal line SL and one control line GL, and is electrically connected to the one signal line SL and one control line GL. One side of the plurality of lead wires LE is connected to the drive circuit DR, and the other side is connected to the pad p of the OLB. The lead wires LE may be connected to the drive circuit DC. The patch electrode PE, the signal line SL, the control line GL, and the common electrode CE are formed of metal or a conductor equivalent to metal.

[0022] Conductors such as the patch electrode PE and the common electrode CE may be formed of so-called TAT or MAM.

[0023] When the patch electrode PE is formed by TAT, the patch electrode PE has a three-layer laminated structure (Ti-based / Al-based / Ti-based). The patch electrode PE has a lower layer made of a metal material whose main component is Ti (titanium) or an alloy containing Ti, a middle layer made of a metal material whose main component is Al (aluminum) or an alloy containing Al, and an upper layer made of a metal material whose main component is Ti or an alloy containing Ti.

[0024] When the patch electrode PE is made of MAM, it has a three-layer laminated structure (Mo-based / Al-based / Mo-based). The patch electrode PE has a lower layer made of a metal material whose main component is Mo, such as Mo or an alloy containing Mo, a middle layer made of a metal material whose main component is Al, such as an alloy containing Al, and an upper layer made of a metal material whose main component is Mo, such as Mo or an alloy containing Mo. For example, the patch electrodes PE, the signal lines SL, and the control lines GL may be formed of a transparent conductive material such as ITO (indium tin oxide).

[0025] The sealant SE is located in the non-reflective area NRA and is disposed on the periphery of the area where the first substrate SUB1 and the second substrate SUB2 face each other. While the liquid crystal layer LC described above is formed by a drop injection method, it may also be formed by a liquid crystal injection method utilizing capillary action. In the latter case, a liquid crystal injection port is formed in the sealant SE, and liquid crystal material is injected through the liquid crystal injection port into the space surrounded by the first substrate SUB1, the second substrate SUB2, and the sealant SE, and the liquid crystal injection port is then sealed with a sealing material.

[0026] 2 shows an example in which eight patch electrodes PE are arranged in each of the directions along the X-axis and the Y-axis. However, the number of patch electrodes PE can be varied in various ways. For example, 100 patch electrodes PE may be arranged in the direction along the X-axis, and a plurality of patch electrodes (e.g., 100) may be arranged in the direction along the Y-axis. The length of the radio wave reflector RE (first substrate SUB1) in the direction along the X-axis is, for example, 40 to 80 cm.

[0027] FIG. 3 is an enlarged cross-sectional view showing a part of the radio wave reflector RE according to this embodiment. 3, in the first substrate SUB1, an insulating layer 11, an insulating layer 12, an insulating layer 13, an insulating layer 14, an insulating layer 15, an insulating layer 16, an insulating layer 17, and an alignment film AL1 are formed in this order on a base material 1. The insulating layers 11 to 17 are each formed of an inorganic insulating layer or an organic insulating layer. In this embodiment, the insulating layer 16 is an organic insulating layer and is formed of, for example, a resin.

[0028] Insulating layers 11 to 15 and 17 are each inorganic insulating layers. Insulating layer 11 is made of SiO (silicon oxide). Insulating layer 12 has a lower layer made of SiN and an upper layer made of SiO. Insulating layer 13 is made of SiO. Insulating layer 14 is made of SiN. Insulating layer 15 is made of SiO or SiN. Insulating layer 17 is made of SiN.

[0029] The control wiring GL and the conductive layer CO1 are provided on an insulating layer 11 and covered with an insulating layer 12. A semiconductor layer SMC is provided on the insulating layer 12. The semiconductor layer SMC is overlaid on the control wiring GL. The semiconductor layer SMC is formed of an oxide semiconductor (OS), which is a transparent semiconductor. Typical examples of oxide semiconductors include indium gallium zinc oxide (InGaZnO), indium gallium oxide (InGaO), indium zinc oxide (InZnO), zinc tin oxide (ZnSnO), zinc oxide (ZnO), and transparent amorphous oxide semiconductor (TAOS). However, the semiconductor layer SMC is not limited to an oxide semiconductor and may be formed of amorphous silicon or low-temperature polycrystalline silicon as polycrystalline silicon.

[0030] The conductive layer CO2 and the connection wiring layer CL1 are provided on the insulating layer 12 and the semiconductor layer SMC and are covered with the insulating layer 13. The connection wiring layer CL1 contacts the conductive layer CO1 through a contact hole formed in the insulating layer 12. The conductive layer CO2 and the connection wiring layer CL1 contact the semiconductor layer SMC and are electrically connected. One of the regions of the semiconductor layer SMC to which the conductive layer CO2 is connected and the other to which the connection wiring layer CL1 is connected is a source region, and the other is a drain region. The semiconductor layer SMC has a channel region between the source region and the drain region.

[0031] The gate electrode GE is provided on the insulating layer 13 and covered with the insulating layer 14. The gate electrode GE is electrically connected to the control line GL. The gate electrode GE overlaps at least the channel region of the semiconductor layer SMC. The control line GL, the semiconductor layer SMC, the gate electrode GE, etc. constitute a switching element SW as a TFT (thin film transistor).

[0032] The region of the control line GL that overlaps with the semiconductor layer SMC functions as a gate electrode. Therefore, the switching element SW is a dual-gate TFT. However, the switching element SW may be a bottom-gate TFT or a top-gate TFT.

[0033] The conductive layer CO3 and the connection wiring layer CL2 are provided on the insulating layer 14 and covered with the insulating layer 15. The conductive layer CO3 is in contact with the gate electrode GE through a contact hole formed in the insulating layer 14. The connection wiring layer CL2 is in contact with the connection wiring layer CL1 through a contact hole formed in the insulating layers 13 and 14.

[0034] The insulating layer 16 and the insulating layer 17 are provided in this order on the insulating layer 15. The patch electrode PE is provided on the insulating layer 17 and is covered with an alignment film AL1. The patch electrode PE passes through contact holes formed in the insulating layers 15, 16, and 17 and is in contact with the connection wiring layer CL2.

[0035] A common electrode CE and an alignment film AL2 are provided in this order on the surface of the base material 2 facing the first substrate SUB1. The control wiring GL, conductive layers CO1, CO2, and CO3, connection wiring layers CL1 and CL2, and gate electrode GE are formed of metal as a low-resistance conductive material. The control wiring GL and gate electrode GE may be formed of Mo (molybdenum), W (tungsten), or an alloy thereof. The connection wiring layers CL1 and CL2 may be formed of TAT or MAM.

[0036] As shown in Figures 2 and 3, multiple patch electrodes PE can be driven individually by active matrix driving. Therefore, multiple patch electrodes PE can be driven independently. For example, the direction of the reflected wave w2 reflected by the radio wave reflector RE can be set to be parallel to the XZ plane or parallel to the YZ plane. Alternatively, the direction of the reflected wave w2 reflected by the radio wave reflector RE can be set to a direction parallel to a third plane other than the XZ plane and the YZ plane. The third plane is defined by the Z axis and a third axis in the XY plane other than the X axis and the Y axis. Since each patch electrode PE can be driven independently, the degree of freedom in the reflection direction of the reflected wave w2 reflected by the radio wave reflector RE can be increased.

[0037] Fig. 4 is an enlarged plan view showing the patch electrode PE. As shown in Fig. 4, the patch electrode PE has a square shape. The shape of the patch electrode PE is not particularly limited, but a square or a perfect circle is preferable. Focusing on the outer shape of the patch electrode PE, a shape with a length-to-width aspect ratio of 1:1 is preferable. This is because, in order to accommodate horizontally polarized waves and vertically polarized waves, it is preferable that the patch electrode PE have a rotationally symmetric structure of 90°.

[0038] The patch electrode PE has a length Px along the X-axis and a length Py along the Y-axis. It is desirable to adjust the lengths Px and Py according to the frequency band of the incident wave w1. Next, an example of a desirable relationship between the frequency band of the incident wave w1 and the lengths Px and Py will be shown. 2.4GHz: Px=Py=35mm 5.0GHz: Px=Py=16.8mm 28GHz: Px=Py=3.0mm

[0039] 5 is an enlarged cross-sectional view showing a part of the radio wave reflector RE, and shows a single reflection control part RH. In FIG. 5, the base material 1 and the like shown in FIG. 3 are omitted. As shown in FIG. 5, the thickness d lThe cell gap is maintained by a plurality of spacers SS. In this embodiment, the spacers SS are columnar spacers that are formed on the second substrate SUB2 and protrude toward the first substrate SUB1.

[0040] The width of the spacer SS is 10 to 20 μm. While the lengths Px and Py of the patch electrode PE are on the order of mm, the width of the spacer SS is on the order of μm. Therefore, it is necessary to have multiple spacers SS in the area facing the patch electrode PE. Furthermore, the proportion of the area facing the patch electrode PE where multiple spacers SS exist is approximately 1%.

[0041] Therefore, even if the spacers SS are present in the above region, the effect of the spacers SS on the reflected wave w2 is slight. The spacers SS may be formed on the first substrate SUB1 and protrude toward the second substrate SUB2. Alternatively, the spacers SS may be spherical spacers.

[0042] The radio wave reflector RE includes a plurality of reflection control parts RH, each of which includes one of the plurality of patch electrodes PE, a portion of the common electrode CE facing the one patch electrode PE, and an area of ​​the liquid crystal layer LC facing the one patch electrode PE.

[0043] 6 is an enlarged cross-sectional view showing a part of the radio wave reflector RE, and shows a plurality of reflection control parts RH. In FIG. 6, the substrate 1, spacers SS, etc. are omitted from the illustration. 6, each reflection control unit RH functions to adjust the phase of the radio wave (incident wave w1) incident from the incident surface Sa side in accordance with the voltage applied to the patch electrode PE, and to reflect the radio wave toward the incident surface Sa to produce a reflected wave w2. In each reflection control unit RH, the reflected wave w2 is a composite wave of the radio wave reflected by the patch electrode PE and the radio wave reflected by the common electrode CE.

[0044] The patch electrodes PE are arranged at equal intervals along the X-axis. The distance (pitch) between adjacent patch electrodes PE is d kLet the length d k corresponds to the distance from the geometric center of one patch electrode PE to the geometric center of the adjacent patch electrode PE. In this embodiment, the description will be given assuming that the reflected waves w2 are in phase in the first reflection direction d1. In the XZ plane of FIG. 6, the first reflection direction d1 is a direction that forms a first angle θ1 with the Z axis. The first reflection direction d1 is parallel to the XZ plane.

[0045] In order for the radio waves reflected by the multiple reflection control parts RH to be in phase with each other in the first reflection direction d1, it is sufficient that the phases of the radio waves are aligned on a straight, two-dot chain line. For example, it is sufficient that the phase of the reflected wave w2 at point Q1b and the phase of the reflected wave w2 at point Q2a are aligned. The physical linear distance from point Q1a to point Q1b on the first patch electrode PE1 is d k × sin θ1. Therefore, when focusing on the first reflection control section RH1 and the second reflection control section RH2, it is sufficient to delay the phase of the reflected wave w2 from the second reflection control section RH2 by a phase amount δ1 from the phase of the reflected wave w2 from the first reflection control section RH1. Here, the phase amount δ1 is expressed by the following equation: δ1=d k ×sinθ1×2π / λ

[0046] Next, a method for driving the radio wave reflector RE will be described. Fig. 7 is a timing chart showing the change in voltage applied to the patch electrode PE for each period in the method for driving the radio wave reflector RE of this embodiment. Fig. 7 shows the first period Pd1 to the fifth period Pd5 of the driving period of the radio wave reflector RE.

[0047] 6 and 7, when the radio wave reflector RE starts to operate, during a first period Pd1, voltages V are applied to the patch electrodes PE so that the radio waves reflected by the reflection control units RH are in phase with each other in a first reflection direction d1. For example, a first voltage V1 is applied to the first patch electrode PE1, a second voltage V2 is applied to the second patch electrode PE2, a third voltage V3 is applied to the third patch electrode PE3, and a fourth voltage V4 is applied to the fourth patch electrode PE4. The absolute values ​​of the voltages V applied to each patch electrode PE are the same throughout the entire period Pd.

[0048] The polarity of the voltage applied to each patch electrode PE is periodically reversed relative to the potential of the common electrode CE. For example, the patch electrodes PE are driven at a driving frequency of 60 Hz. As described above, the patch electrodes PE are driven with AC current.

[0049] Even when the period Pd is changed to another period Pd, the phase difference δ1 between the radio wave reflected in the first reflection direction d1 by one reflection control unit RH and the radio wave reflected in the first reflection direction d1 by the adjacent reflection control unit RH is maintained. In this embodiment, the phase difference δ1 is 35°. Therefore, a phase difference of 245° is provided between the radio wave reflected in the first reflection direction d1 by the first reflection control unit RH1 including the first patch electrode PE1 and the radio wave reflected in the first reflection direction d1 by the eighth reflection control unit RH8 including the eighth patch electrode PE8.

[0050] (First Example of the First Embodiment) Next, a first example of the first embodiment will be described. Fig. 8 is a cross-sectional view showing a radio wave reflector RE according to the first example of the present embodiment. In the drawing, the alignment films AL1, AL2, etc. are omitted.

[0051] As shown in FIG. 8, the substrate 1 is located in a reflective area RA and a non-reflective area NRA. The substrate 1 has a principal surface S1 as a first principal surface and a principal surface S2 as a second principal surface. The principal surface S2 is the surface opposite to the principal surface S1. A plurality of patch electrodes PE are located in the reflective area RA and face the principal surface S1. The principal surface S2 functions as an incident surface Sa. In this first embodiment, the substrate 1 is in contact with the atmosphere and functions as a cover member. The substrate 1 can also be referred to as a cover glass or a protective layer.

[0052] The substrate 2 is located in a reflective region RA and a non-reflective region NRA. The substrate 2 has a principal surface S3 as a third principal surface and a principal surface S4 as a fourth principal surface. The principal surface S3 faces the principal surface S1. The principal surface S4 is the surface opposite to the principal surface S3. The common electrode CE is located at least in the reflective region RA, and is provided between the first substrate SUB1 and the principal surface S3. The common electrode CE faces a plurality of patch electrodes PE in a direction parallel to the Z axis.

[0053] The radio wave reflector RE includes a radio wave absorber A located in the non-reflection area NRA. In this first embodiment, the radio wave absorber A is a λ / 4 type radio wave absorber. The radio wave absorber A includes a first conductive layer LA1, a second conductive layer LA2, and a dielectric layer DL. The second conductive layer LA2 is provided on the side of the first conductive layer LA1 on which the radio wave is incident, that is, on the incident surface Sa. The second conductive layer LA2 faces the first conductive layer LA1 in a direction parallel to the Z axis. The dielectric layer DL is sandwiched between the first conductive layer LA1 and the second conductive layer LA2. Note that a plurality of patch electrodes PE are located between the second substrate SUB2 and the incident surface Sa.

[0054] The dielectric layer DL has at least a substrate 1. In this Example 1, the first conductive layer LA1 is located between the insulating layer 11 and the alignment film AL1. Therefore, the dielectric layer DL has not only the substrate 1 but also the insulating layer 11. In the direction parallel to the Z axis, the thickness of the dielectric layer DL is different from the thickness Tb of the substrate 1. In this Example 1, the thickness of the dielectric layer DL is larger than the thickness Tb. The thickness of the dielectric layer DL is equivalent to λ / 4.

[0055] The first conductive layer LA1 is formed of metal. The electrical resistance of the second conductive layer LA2 is higher than that of the first conductive layer LA1. For example, the second conductive layer LA2 is formed of a conductive material with a higher electrical resistance than the first conductive layer LA1. In this Example 1, the second conductive layer LA2 is formed of a transparent conductive material, such as ITO. The resistance of the second conductive layer LA2 may be set to be equal to the resistance of the air layer. In terms of sheet resistance, it is preferable that the second conductive layer LA2 has a sheet resistance of substantially 376 Ω / □ (ohms per square). It is desirable that the second conductive layer LA2 have a sheet resistance of 200 to 500 Ω / □. Alternatively, in order to increase the resistance of the second conductive layer LA2, the second conductive layer LA2 may be formed in a mesh shape using metal.

[0056] The first conductive layer LA1 is electrically connected to ground (GND), but may be at the same potential as the common electrode CE. It is preferable that no voltage is applied to the liquid crystal layer LC sandwiched between the common electrode CE and the first conductive layer LA1. The first conductive layer LA1 may be in an electrically floating state. The second conductive layer LA2 is in an electrically floating state.

[0057] As described above, the radio wave absorber A is composed of the first conductive layer LA1, the second conductive layer LA2, and the dielectric layer DL. The radio wave absorber A can absorb the reflected wave that is reflected when the incident wave w1 is incident. By providing the radio wave absorber A over the entire non-reflection area NRA, it is possible to suppress unwanted reflection in the non-reflection area NRA. Compared to a case in which the radio wave absorber A is not provided on the radio wave reflector RE, it is possible to suppress interference between the regular reflected wave w2 from the reflection area RA of the radio wave reflector RE and the undesired reflected wave from the non-reflection area NRA of the radio wave reflector RE. Therefore, it is possible to obtain a radio wave reflector RE that can suppress deterioration in the reflection characteristics.

[0058] From the viewpoint of suppressing unnecessary reflection in the non-reflective area NRA, it is desirable that the driving circuit DR and wiring such as the lead wires LE be provided between the first conductive layer LA1 and the alignment film AL1. Note that an insulating layer is interposed between the first conductive layer LA1 and the driving circuit DR, and between the first conductive layer LA1 and wiring such as the lead wires LE. This allows the radio wave absorber A to effectively absorb reflected waves.

[0059] However, the first conductive layer LA1 may be formed on the same layer as the patch electrode PE using the same material. The first conductive layer LA1 is formed between the insulating layer 17 and the alignment film AL1. In this case, wiring such as the drive circuit DR and the lead wires LE may be provided between the substrate 1 and the first conductive layer LA1, and the radio wave absorber A can absorb reflected waves.

[0060] (Second Example of the First Embodiment) Next, a second example of the first embodiment will be described. Fig. 9 is a cross-sectional view showing a radio wave reflector RE according to the second example of the present embodiment. In the drawing, the alignment films AL1, AL2, etc. are omitted.

[0061] As shown in Fig. 9, the position of the wave absorber A in the direction parallel to the Z axis is different from the position of the wave absorber A in the first embodiment. The wave absorber A has a first conductive layer LA1, a second conductive layer LA2, and a dielectric layer DL. The dielectric layer DL has at least a liquid crystal layer LC. Here, the dielectric layer DL further has a sealant SE.

[0062] In this Example 2, the first conductive layer LA1 is located between the substrate 2 and the alignment film AL2. The second conductive layer LA2 is located between the substrate 1 and the alignment film AL1. Therefore, the dielectric layer DL further includes alignment films AL1 and Al2. In the direction parallel to the Z axis, the thickness of the dielectric layer DL is different from the thickness Tb of the substrate 1. In this Example 2, the thickness of the dielectric layer DL is smaller than the thickness Tb.

[0063] The first conductive layer LA1 is made of metal. The first conductive layer LA1 may be made of the same material as the common electrode CE and formed in the same layer. Alternatively, the first conductive layer LA1 and the common electrode CE may be formed continuously and integrally.

[0064] The electrical resistance of the second conductive layer LA2 is higher than the electrical resistance of the first conductive layer LA1. In this second embodiment, the second conductive layer LA2 is made of ITO and preferably has a sheet resistance of 200 to 500 Ω / □.

[0065] The first conductive layer LA1 is electrically connected to ground (GND). The potential of the first conductive layer LA1 is substantially 0V. The first conductive layer LA1 may be in an electrically floating state. When the first conductive layer LA1 and the common electrode CE are integrally formed, the potential of the first conductive layer LA1 is fixed to 0V by applying a common voltage to the first conductive layer LA1. The second conductive layer LA2 is provided at an electrically insulating distance from a conductor such as the patch electrode PE, and is in an electrically floating state. In the non-reflective area NRA, the liquid crystal layer LC is not driven by the first conductive layer LA1 and the second conductive layer LA2, and therefore the dielectric constant of the dielectric layer DL is fixed.

[0066] The radio wave absorber A can absorb the reflected wave that is reflected when the incident wave w1 is incident on it, and therefore it is possible to obtain a radio wave reflector RE that can suppress the deterioration of the reflection characteristics. It is desirable that the drive circuit DR and wiring such as the lead wires LE are provided between the second conductive layer LA2 and the alignment film AL1. Note that an insulating layer is interposed between the second conductive layer LA2 and the drive circuit DR, and between the second conductive layer LA2 and wiring such as the lead wires LE. This allows the radio wave absorber A to effectively absorb reflected waves.

[0067] However, wiring such as the drive circuit DR and lead wires LE may be provided between the substrate 1 and the second conductive layer LA2. The second conductive layer LA2 may be formed in the same layer as the patch electrode PE and made of the same material. In this case, the radio wave absorber A can also absorb reflected waves.

[0068] (Third Example of the First Embodiment) Next, a third example of the first embodiment will be described. Fig. 10 is a cross-sectional view showing a radio wave reflector RE according to the third example of the present embodiment. In the drawing, the alignment films AL1, AL2, etc. are omitted.

[0069] As shown in FIG. 10, the position of the radio wave absorber A in the direction parallel to the Z axis is different from the position of the radio wave absorber A in the first embodiment and also different from the position of the radio wave absorber A in the second embodiment. The radio wave absorber A is located closer to the incident surface Sa than the first substrate SUB1. The radio wave reflector RE further includes a dielectric substrate 5. In this third embodiment, the dielectric substrate 5 is a glass substrate. However, the dielectric substrate 5 may be formed of a dielectric material other than glass, such as resin. The dielectric substrate 5 has a main surface S5 as a fifth main surface and a main surface S6 as a sixth main surface. The main surface S5 faces the main surface S2 of the base material 1. The main surface S6 is the surface opposite to the main surface S5. The dielectric substrate 5 is bonded to the first substrate SUB1 by an adhesive layer AD.

[0070] In this third embodiment, the dielectric substrate 5 is located in a reflective area RA and a non-reflective area NRA. The main surface S6 functions as the incident surface Sa. The dielectric substrate 5 is located not only in the non-reflective area NRA but also in the reflective area RA. Therefore, compared to when the dielectric substrate 5 is located in both the non-reflective area NRA and the reflective area RA, the radio wave reflector RE can have a flat surface (incident surface Sa).

[0071] In the third embodiment, the dielectric substrate 5 is in contact with the atmosphere and functions as a cover member. The dielectric substrate 5 can also be called a cover glass or a protective layer. However, the dielectric substrate 5 of the third embodiment only needs to be located in at least the non-reflective area NRA, and does not necessarily have to be located in the reflective area RA.

[0072] The wave absorber A has a first conductive layer LA1, a second conductive layer LA2, and a dielectric layer DL. The dielectric layer DL has at least a dielectric substrate 5. Here, the dielectric layer DL further has an adhesive layer AD.

[0073] In this Example 3, the first conductive layer LA1 is located between the base material 1 and the dielectric substrate 5. The second conductive layer LA2 faces the main surface S6. Here, the first conductive layer LA1 is formed on the main surface S2, and the second conductive layer LA2 is formed on the main surface S6. In the direction parallel to the Z axis, the thickness Ta of the dielectric layer DL may be the same as or different from the thickness Tb of the base material 1. In this Example 3, the thickness Ta is greater than the thickness Tb.

[0074] The first conductive layer LA1 is made of metal. The electrical resistance of the second conductive layer LA2 is higher than the electrical resistance of the first conductive layer LA1. In this Example 3, the second conductive layer LA2 is formed of ITO and preferably has a sheet resistance value of 200 to 500 Ω / □.

[0075] The first conductive layer LA1 is electrically connected to ground (GND). The potential of the first conductive layer LA1 is substantially 0V. The first conductive layer LA1 may be in an electrically floating state. The second conductive layer LA2 is in an electrically floating state. The radio wave absorber A can absorb the reflected wave that is reflected when the incident wave w1 is incident on it, and therefore it is possible to obtain a radio wave reflector RE that can suppress the deterioration of the reflection characteristics.

[0076] Next, a means for fixing the potential of the first conductive layer LA1 will be described. Fig. 11 is an enlarged cross-sectional view showing a portion of a radio wave reflector RE according to a third example of the first embodiment, and is a diagram for explaining a first means for fixing the potential of the first conductive layer LA1. Fig. 12 is an enlarged cross-sectional view showing a portion of a radio wave reflector RE and a cable CA according to a third example of the first embodiment, and is a diagram for explaining a second means for fixing the potential of the first conductive layer LA1. In Figs. 11 and 12, only the components necessary for explanation are shown for the first substrate SUB1 and the second substrate SUB2, and the adhesive layer AD and other components of the radio wave reflector RE are omitted.

[0077] 11, the first substrate SUB1 has a power supply pad pA facing the main surface S1 of the base material 1. The second substrate SUB2 has a power receiving pad pB facing the main surface S3 of the base material 2. Here, the power receiving pad pB and the common electrode CE are formed continuously and integrally. The power supply pad pA and the power receiving pad pB are located outside the sealing material SE.

[0078] The radio wave reflector RE further includes a transfer TM. The transfer TM is located outside the sealing material SE and is arranged so as not to come into contact with the liquid crystal layer LC. The transfer TM is in contact with the power supply pad pA and the power receiving pad pB. Therefore, the power supply pad pA can apply a common voltage to the power receiving pad pB via the transfer TM.

[0079] The radio wave reflector RE further includes a conductive material CON. The conductive material CON can be rephrased as a connecting wiring. The conductive material CON is in contact with the first conductive layer LA1, the side surface Si of the substrate 1, the power supply pad pA, the transfer TM, and the power receiving pad pB, and electrically connects the first conductive layer LA1 and the power supply pad pA. This allows the power supply pad pA to apply a common voltage to the first conductive layer LA1 at least via the conductive material CON. This allows the first conductive layer LA1 to be substantially connected to ground. Since the first means in FIG. 11 is the conductive material CON provided in the radio wave reflector RE, the potential of the first conductive layer LA1 is fixed inside the radio wave reflector RE.

[0080] As shown in Fig. 12, a cable CA may be connected to the radio wave reflector RE. The cable CA is electrically connected to an area of ​​the first conductive layer LA1 that is not covered by the dielectric substrate 5. The second means in Fig. 12 is the cable CA, which can fix the potential of the first conductive layer LA1.

[0081] Furthermore, as can be seen from FIGS. 11 and 12, in this third embodiment, the first conductive layer LA1 can be formed in a region that overlaps the power supply pad pA and the transfer TM in the direction along the Z axis.

[0082] According to the first embodiment configured as described above, the radio wave reflector RE includes the radio wave absorber A. The radio wave absorber A can suppress unnecessary reflection in the non-reflection area NRA. Therefore, it is possible to obtain a radio wave reflector RE that can suppress deterioration in reflection characteristics. As a result, it is possible to obtain a radio wave reflector RE with excellent reflection characteristics.

[0083] Next, a second embodiment will be described. The radio wave reflector RE of the second embodiment has the same structure as that of the first embodiment, except for the structure described in the second embodiment.

[0084] (First Example of the Second Embodiment) First, a first example of the second embodiment will be described. Fig. 13 is a cross-sectional view showing a radio wave reflector RE according to the first example of the second embodiment. In the drawing, the alignment films AL1, AL2, etc. are omitted. In the first example of the second embodiment, differences from the first example of the first embodiment will be described.

[0085] As shown in Fig. 13, the wave absorber A has a first conductive layer LA1, a second conductive layer LA2, and a dielectric layer DL. Compared to the first example of the first embodiment, the wave absorber A has a different configuration of the second conductive layer LA2. The second conductive layer LA2 has a plurality of frequency selective surfaces F. The frequency selective surfaces F are made of metal. In this case, the frequency selective surfaces F can be referred to as metal layers.

[0086] 14 is an enlarged cross-sectional view showing a part of the radio wave reflector RE of the first example of the second embodiment, and shows a plurality of patch electrodes PE, a plurality of frequency selective plates F, and a sealing material SE, which is indicated by a diagonal line slanting downward to the right. As shown in Fig. 14, multiple frequency selective plates F are arranged in an island shape in the non-reflective area NRA. Each frequency selective plate F has at least one of a shape different from the shape of the patch electrode PE and a size different from the size of the patch electrode PE. In this first embodiment, the frequency selective plate F has a shape (square) similar to the patch electrode PE and a size smaller than the patch electrode PE. Furthermore, multiple frequency selective plates F have the same shape and size and are aligned along the X-axis and Y-axis.

[0087] The frequency selective surfaces F are in an electrically floating state. The arrangement of the multiple frequency selective plates F, the shape of the frequency selective plates F, and the size of the frequency selective plates F are adjusted so that reflections (unwanted reflections) in the non-reflective areas NRA can be suppressed more than reflections (regular reflections) in the reflective areas RA. This allows the non-reflective areas NRA of the radio wave absorber A to be areas with relatively low reflectivity. Note that the size of the frequency selective plates F may be made larger than the size of the patch electrode PE to suppress unwanted reflections in the non-reflective areas NRA. The plurality of frequency selective plates F may overlap the sealing material SE in plan view.

[0088] Here, some modified examples of the patterns of the plurality of frequency selective plates F will be described. As shown in Fig. 15, the plurality of frequency selective plates F may include a plurality of types of frequency selective plates with different sizes. In the example shown in Fig. 15, the plurality of frequency selective plates F include two types of frequency selective plates F1 and F2 with different sizes.

[0089] As shown in Fig. 16, the frequency selective plate F may be a frequency selective plate F3 having a rectangular shape and extending along the Y axis, or as shown in Fig. 17, the frequency selective plate F may be a frequency selective plate F4 having a rectangular shape and extending along the X axis.

[0090] Alternatively, the frequency selective plate F3 and the frequency selective plate F4 may be mixed in the non-reflective area NRA. For example, the frequency selective plate F3 may be arranged in a pair of areas of the non-reflective area NRA that sandwich the reflective area RA in the direction along the X axis, and the frequency selective plate F4 may be arranged in another pair of areas of the non-reflective area NRA that sandwich the reflective area RA in the direction along the Y axis.

[0091] However, when the frequency selective plate F does not have a shape that is rotationally asymmetric by 90 degrees, like the frequency selective plates F3 and F4, the frequency selective plate F only needs to have a length that is insensitive to both vertically polarized waves and horizontally polarized waves. In other words, the shape and size (length, etc.) of the frequency selective plate F only need to be adjusted so that no matter how the amplitude direction of the radio waves changes relative to the radio wave reflector RE, there is no point where the reflection intensity increases in the non-reflection area NRA of the radio wave reflector RE.

[0092] As described above, the radio wave absorber A is composed of the first conductive layer LA1, multiple frequency selective surfaces F, and a dielectric layer DL. The radio wave absorber A can absorb the reflected wave that is reflected when an incident wave w1 is incident. By providing the radio wave absorber A over the entire non-reflection area NRA, it is possible to suppress unnecessary reflection in the non-reflection area NRA.

[0093] The frequency selective plate F is not limited to metal, and may be formed of a transparent conductive material such as ITO. However, if the material of the frequency selective plate F is changed to ITO, the size of the frequency selective plate F must also be changed. Therefore, the size of the frequency selective plate F should be determined appropriately so as to suppress reflection in the non-reflective area NRA.

[0094] (Second Example of the Second Embodiment) Next, a second example of the second embodiment will be described. Fig. 18 is a cross-sectional view showing a radio wave reflector RE according to the second example of the second embodiment. In the drawing, the alignment films AL1, AL2, etc. are omitted. In the second example of the second embodiment, differences from the first example of the second embodiment and the second example of the first embodiment will be described.

[0095] As shown in Fig. 18, the radio wave absorber A has a first conductive layer LA1, a second conductive layer LA2, and a dielectric layer DL. The second conductive layer LA2 has a plurality of frequency selective surfaces F. The radio wave absorber A can absorb the reflected wave that is reflected when an incident wave w1 is incident. Therefore, a radio wave reflector RE that can suppress deterioration in reflection characteristics can be obtained.

[0096] (Third Example of the Second Embodiment) Next, a third example of the second embodiment will be described. Fig. 19 is a cross-sectional view showing a radio wave reflector RE according to the third example of the second embodiment. In the drawing, the alignment films AL1, AL2, etc. are omitted. In the third example of the second embodiment, differences from the first example of the second embodiment and the third example of the first embodiment will be described.

[0097] 19, the radio wave absorber A has a first conductive layer LA1, a second conductive layer LA2, and a dielectric layer DL. The second conductive layer LA2 has a plurality of frequency selective surfaces F. In the third embodiment as well, a radio wave reflector RE that can suppress deterioration in reflection characteristics can be obtained. In the second embodiment configured as above, the same effects as those of the first embodiment can be obtained.

[0098] Next, a third embodiment will be described. The radio wave reflector RE of the third embodiment has the same structure as that of the first embodiment, except for the structure described in the third embodiment.

[0099] (First Example of the Third Embodiment) First, a first example of the third embodiment will be described. Fig. 20 is a cross-sectional view showing a radio wave reflector RE according to the first example of the third embodiment. In the drawing, the alignment films AL1, AL2, etc. are omitted. In the first example of the third embodiment, differences from the first example of the first embodiment (Fig. 8) will be described.

[0100] As shown in FIG. 20, the radio wave absorber A includes a dielectric layer DL but does not include a first conductive layer LA1 or a second conductive layer LA2. The radio wave reflector RE further includes a dielectric substrate 5. In this first embodiment, the dielectric substrate 5 is a glass substrate. However, the dielectric substrate 5 may be formed of a dielectric material other than glass, such as resin. The dielectric substrate 5 has a main surface S5 and a main surface S6. The dielectric substrate 5 is adhered to the first substrate SUB1 by an adhesive layer AD.

[0101] The dielectric layer DL is located in the reflective area RA and the non-reflective area NRA. The dielectric layer DL has at least a substrate 1. The dielectric layer DL is provided between the main surface S1 of the substrate 1 and the incident surface Sa. In this first embodiment, the dielectric layer DL has not only the substrate 1 but also an adhesive layer AD and a dielectric substrate 5.

[0102] The plurality of patch electrodes PE are located between the second substrate SUB2 and the incident surface Sa. The radio wave absorber A has a portion located in the non-reflection region NRA of the dielectric layer DL. In the direction parallel to the Z axis, the thickness Ta1 of the non-reflection region NRA of the dielectric layer DL is different from the thickness Ta2 of the reflective region RA of the dielectric layer DL.

[0103] In the third embodiment, the dielectric substrate 5 is located in the reflective region RA, but not in the non-reflective region NRA. Therefore, the thickness Ta1 is smaller than the thickness Ta2. In the reflective region RA, the main surface S6 functions as the incident surface Sa.

[0104] The thickness Ta2 is set so that the amplitude of the normal reflected wave w2 from the reflective area RA of the radio wave reflector RE is large. The thickness Ta1 is different from the thickness Ta2 so that the amplitude of the undesired reflected wave from the non-reflective area NRA of the radio wave reflector RE is relatively small. The radio wave absorber A can absorb the reflected wave that is reflected when the incident wave w1 is incident. By providing the radio wave absorber A over the entire non-reflective area NRA, it is possible to suppress unnecessary reflection in the non-reflective area NRA. Therefore, a radio wave reflector RE can be obtained that can suppress deterioration of the reflection characteristics.

[0105] (Second Example of the Third Embodiment) Next, a second example of the third embodiment will be described. Fig. 21 is a cross-sectional view showing a radio wave reflector RE according to the second example of the third embodiment. In the drawing, the alignment films AL1, AL2, etc. are omitted. In the second example of the third embodiment, differences from the first example of the third embodiment will be described.

[0106] As shown in Fig. 21, the second embodiment differs from the first embodiment in the position of the dielectric substrate 5. The dielectric substrate 5 is located in the non-reflective area NRA, not in the reflective area RA. Therefore, the thickness Ta1 is greater than the thickness Ta2. In the reflective area RA, the main surface S2 functions as the incident surface Sa.

[0107] The thickness Ta2 is set so that the amplitude of the regular reflected wave w2 from the reflection area RA of the radio wave reflector RE is large. The thickness Ta1 is different from the thickness Ta2 so that the amplitude of the undesired reflected wave from the non-reflection area NRA of the radio wave reflector RE is relatively small. The radio wave absorber A has a dielectric layer DL located in the non-reflection area NRA, and can absorb the reflected wave that is reflected when the incident wave w1 is incident. By providing the radio wave absorber A over the entire non-reflection area NRA, it is possible to suppress unnecessary reflection in the non-reflection area NRA. Therefore, a radio wave reflector RE can be obtained that can suppress deterioration of the reflection characteristics.

[0108] The third embodiment configured as described above can also achieve the same effects as the first embodiment. By adjusting the thickness of the dielectric substrate 5, the thickness Ta2 in the first example (FIG. 20) and the thickness Ta1 in the second example (FIG. 21) can be adjusted to desired values. Alternatively, the radio wave reflector RE may include multiple dielectric substrates including the dielectric substrate 5. In this case, the thicknesses Ta1 and Ta2 can be adjusted by the multiple dielectric substrates, etc.

[0109] (Fourth embodiment) Next, a fourth embodiment will be described. The radio wave reflector RE of the fourth embodiment has the same configuration as the first to third embodiments except for the configuration described in the fourth embodiment. Fig. 22 is a plan view showing the radio wave reflector RE according to the fourth embodiment.

[0110] 22, the first substrate SUB1 has connection wirings L and wirings WL instead of the signal wirings SL, control wirings GL, switching elements SW, drive circuits DR, and lead wires LE. The patch electrodes PE are included in patch electrode groups GP that extend along the Y axis and are arranged along the X axis. The patch electrode groups GP include a first patch electrode group GP1 to an eighth patch electrode group GP8.

[0111] The first patch electrode group GP1 has a plurality of first patch electrodes PE1, the second patch electrode group GP2 has a plurality of second patch electrodes PE2, the third patch electrode group GP3 has a plurality of third patch electrodes PE3, the fourth patch electrode group GP4 has a plurality of fourth patch electrodes PE4, the fifth patch electrode group GP5 has a plurality of fifth patch electrodes PE5, the sixth patch electrode group GP6 has a plurality of sixth patch electrodes PE6, the seventh patch electrode group GP7 has a plurality of seventh patch electrodes PE7, and the eighth patch electrode group GP8 has a plurality of eighth patch electrodes PE8. For example, the second patch electrode PE2 is located between the first patch electrode PE1 and the third patch electrode PE3 in the direction along the X-axis.

[0112] Each patch electrode group GP includes a plurality of patch electrodes PE arranged along the Y-axis and electrically connected to one another. In this embodiment, the plurality of patch electrodes PE of each patch electrode group GP are electrically connected by connection wiring L. The first substrate SUB1 has a plurality of connection wirings L extending along the Y-axis and arranged along the X-axis. The connection wirings L extend to an area of ​​the base material 1 that does not face the second substrate SUB2. Unlike this embodiment, the plurality of connection wirings L may be connected one-to-one to the plurality of patch electrodes PE. Each of the wirings WL connects one of the connection wirings L to the drive circuit DC.

[0113] In this embodiment, the patch electrodes PE arranged along the Y axis, the connection wiring L, and the wiring WL are integrally formed of the same conductor. However, the patch electrodes PE, the connection wiring L, and the wiring WL may be formed of different conductors.

[0114] The connection wiring L is a thin wire, and the width of the connection wiring L is sufficiently smaller than the length Px. The width of the connection wiring L is several μm to several tens of μm, on the order of μm. Note that if the width of the connection wiring L is made too large, it is not desirable because it will change the sensitivity to the frequency components of the radio wave. In this embodiment, the direction of the reflected wave w2 reflected by the radio wave reflector RE is parallel to the XZ plane.

[0115] 23 is a perspective view showing a reflecting device 100 according to the fourth embodiment. In the drawing, a frame 120 is indicated by a dashed line. As shown in FIG. 23, the reflecting device 100 includes a radio wave reflecting plate RE, a support portion 110, and the frame 120.

[0116] The support 110 supports the radio wave reflector RE. The support 110 is the leg of the reflecting device 100 and is fixed to the installation surface. It is desirable that the support 110 be made of an insulating material so as not to inadvertently reflect radio waves. Note that if a metal layer (metal portion) is present on the support 110, the metal layer will reflect radio waves. For this reason, it is undesirable to provide a metal layer on the support 110.

[0117] The frame 120 surrounds the periphery of the radio wave reflector RE and protects the periphery of the radio wave reflector RE. As with the support part 110, the frame 120 is preferably formed of an insulating material. The reflecting device 100 may include the frame 120 as needed.

[0118] The frame 120 may have radio wave absorbing ability. The frame 120 may constitute a part of the radio wave absorber A. Alternatively, the frame 120 may function as a radio wave absorber separate from the radio wave absorber A. In this case, the radio wave absorber A may be located between the reflective area RA and the frame 120 in a plan view.

[0119] Alternatively, the frame 120 may not have radio wave absorbing capability. In this case, the radio wave absorber A may be located between the reflective area RA and the frame 120 in a plan view. In the fourth embodiment configured as above, the same effects as those of the first to third embodiments can be obtained.

[0120] Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the scope of the invention and its equivalents as defined in the claims.

Claims

1. a first substrate including: a first base material having a first main surface and a second main surface opposite to the first main surface, the first base material being located in a first region and a second region outside the first region; and a plurality of patch electrodes located in the first region, facing the first main surface, and arranged in a matrix at intervals along an X-axis and a Y-axis perpendicular to each other; a second substrate including: a second base material located in the first region and the second region, the second base material having a third main surface facing the first main surface and a fourth main surface opposite the third main surface; and a common electrode located in the first region, provided between the first substrate and the third main surface, and facing the plurality of patch electrodes in a direction parallel to a Z axis orthogonal to each of the X axis and the Y axis; a sealant located in the second region and joining the first substrate and the second substrate; a liquid crystal layer held between the first substrate and the second substrate and surrounded by the sealing material; a radio wave absorber located in the second region.

2. 2. The radio wave reflector according to claim 1, wherein the intensity of the reflected wave of the radio wave incident on the second area as a reflection surface is smaller than the intensity of the reflected wave of the radio wave incident on the first area as a reflection surface.

3. The radio wave absorber is a first conductive layer; a second conductive layer provided on an incident surface side to which radio waves are incident from the first conductive layer and facing the first conductive layer in a direction parallel to the Z axis; a dielectric layer sandwiched between the first conductive layer and the second conductive layer; The radio wave reflector according to claim 1 , wherein the plurality of patch electrodes are located between the second substrate and the incident surface.

4. the first conductive layer is formed of a metal; The radio wave reflector according to claim 3 , wherein the second conductive layer is made of a conductive material having a higher electrical resistance than the first conductive layer.

5. The radio wave reflector according to claim 4 , wherein the second conductive layer is made of a transparent conductive material.

6. The radio wave reflector according to claim 4 , wherein the second conductive layer has a sheet resistance of 200 to 500 Ω / □.

7. the first conductive layer is electrically connected to ground or is in an electrically floating state; The radio wave reflector according to claim 3 , wherein the second conductive layer is in an electrically floating state.

8. The radio wave reflector according to claim 7 , wherein the second conductive layer comprises a plurality of frequency selective surfaces.

9. the plurality of patch electrodes, the common electrode, the first conductive layer, and the plurality of frequency selective surfaces are each formed of a metal; the plurality of patch electrodes have the same shape and the same size; 9. The radio wave reflector according to claim 8, wherein each of the frequency selective surfaces has at least one of a shape different from a shape of the patch electrode and a size different from a size of the patch electrode.

10. The radio wave reflector according to claim 3 , wherein the dielectric layer comprises the first substrate.

11. The radio wave reflector according to claim 3 , wherein the thickness of the dielectric layer is different from the thickness of the first substrate in the direction parallel to the Z axis.

12. a dielectric layer having the first base material, positioned in the first region and the second region, and provided between the first main surface and an incident surface on which radio waves are incident, the plurality of patch electrodes are located between the second substrate and the incident surface; the wave absorber has a portion located in the second region of the dielectric layer, The radio wave reflector according to claim 1 , wherein the thickness of the second region of the dielectric layer is different from the thickness of the first region of the dielectric layer in the direction parallel to the Z axis.

13. the dielectric layer further includes a dielectric substrate facing the second main surface and positioned in the first region, The radio wave reflector according to claim 12 , wherein the thickness of the second region of the dielectric layer is smaller than the thickness of the first region of the dielectric layer.

14. the dielectric layer further includes a dielectric substrate facing the second main surface and positioned in the second region, The radio wave reflector according to claim 12 , wherein the thickness of the second region of the dielectric layer is greater than the thickness of the first region of the dielectric layer.

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