JP7743799B2 - Antenna device and electronic device - Google Patents

Description

This disclosure relates to an antenna device and an electronic device.

Conventionally, there has been an antenna-on-display in which a coplanar waveguide is connected to an antenna element provided on the surface of a substrate, and the antenna element and coplanar waveguide are formed from a transparent conductor, and the antenna device is mounted on a display. The transparent conductor is a metal mesh that is so fine it is invisible to the human eye. The metal mesh is rhomboidal, and the length of the rhomboid along the extension direction of the coplanar waveguide is longer than the length along the width direction, which is perpendicular to the extension direction of the coplanar waveguide in a planar view (see, for example, Non-Patent Document 1).

An Optically Invisible Antenna-on-Display Concept for Millimeter-Wave 5G Cellular Devices, IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION, VOL. 67, NO. 5, MAY 2019

However, with regard to conventional antenna devices, there is no description of the specific relationship between the pixel arrangement direction of the display device and the diamond shape of the metal mesh. Furthermore, there is no description of the advantages or reasons for making the length of the diamond shape along the extension direction of the coplanar waveguide longer than the length along the width direction of the coplanar waveguide.

The objective is to provide an antenna device and electronic device that uses a metal mesh and can simultaneously suppress moire and improve antenna characteristics.

An antenna device according to an embodiment of the present disclosure includes a first insulator substrate, an antenna element formed of a metal mesh and provided on a surface of the first insulator substrate, and a feed line formed of a metal mesh and provided on the surface of the first insulator substrate, the feed line extending between a first end and a second end connected to a feed portion of the antenna element, wherein the feed line extends from the first end in a second axial direction with respect to a first axis and a second axis that are included on the surface and are orthogonal to each other, and the first insulator substrate is provided on a display surface side of a display device, and the antenna element is provided on a surface of the display device. The pixels are arranged along the first axis direction and the second axis direction, the metal mesh of the antenna element and the feed line includes a plurality of cells having a first length in the first axis direction and a second length in the second axis direction, the extension direction of the thin metal wires constituting the plurality of cells is angled with respect to the first axis direction and the second axis direction, the second length is longer than the first length, a first pitch of the plurality of pixels in the first axis direction is different from the first length, and a second pitch of the plurality of pixels in the second axis direction is different from the second length .

This technology uses a metal mesh to provide an antenna device and electronic device that can simultaneously suppress moire and improve antenna characteristics.

1 is an overall view showing an example of the position of an antenna device 100 in an electronic device 200 equipped with a display module D. FIG. 2 is a diagram showing an example of the cross-sectional configuration of the electronic device 200 of FIG. 1 taken along the line AA. 1 is a diagram showing an example of a cross-sectional configuration of a display module D. FIG. FIG. 1 is a perspective view showing an example of the configuration of an antenna device 100. FIG. 2 is a diagram illustrating an example of an antenna device 100 in an exploded state. 1A and 1B are diagrams illustrating an example of the configuration of a transparent conductor 30 of the antenna device 100. 10 is an exemplary diagram illustrating why the length Y30A in the Y direction is longer than the length X30A in the X direction. FIG. 10 is a diagram illustrating an example of frequency characteristics of the S11 parameter of the antenna device 100. FIG. 1 is a diagram showing an example of the directivity of the antenna device 100 in the YZ plane. 10 is a diagram showing an example of the relationship between the shape of the cell of the transparent conductor 30 and the efficiency and peak gain. FIG. FIG. 10 is a diagram illustrating an example of the configuration of a cell 30MA1 according to a modified example of the embodiment. FIG. 10 is a diagram illustrating an example of the configuration of a cell 30MA2 according to a modified example of the embodiment.

The following describes embodiments in which the antenna device and electronic device disclosed herein are applied. In the following, identical elements are denoted by the same reference numerals, and duplicate descriptions may be omitted.

The following explanation defines the XYZ coordinate system. The direction parallel to the X axis (X direction), the direction parallel to the Y axis (Y direction), and the direction parallel to the Z axis (Z direction) are perpendicular to one another. For ease of explanation, the -Z direction may be referred to as the lower side or bottom, and the +Z direction may be referred to as the upper side or top. A planar view refers to a view from the XY plane. The following explanation may exaggerate the length, width, thickness, etc. of each part to make the configuration easier to understand. Terms such as parallel, right angle, orthogonal, horizontal, vertical, and up and down may be misaligned to the extent that they do not impair the effects of the embodiment.

<Embodiment>
<Electronic equipment 200>
1 and 2, the configuration of an electronic device 200, which is an example of a communication device equipped with a display module D including an antenna device 100 according to the present disclosure, will be described. Fig. 1 is an overall view showing an example of the position of the antenna device 100 in the electronic device 200 equipped with the display module D. Fig. 2 is a diagram showing an example of the configuration of a cross section of the electronic device 200 in Fig. 1 taken along the line A-A.

In Figures 1 and 2, the X direction indicates the vertical direction of electronic device 200 (the long direction of the device), the Y direction indicates the horizontal direction of electronic device 200 (the short direction of the device), and the Z direction indicates the height direction of electronic device 200. In the following explanation, the XYZ coordinate system is defined. Also, for the sake of convenience, a planar view refers to an XY plane view, and explanations are given using the vertical direction, with the +Z direction side being the top and the -Z direction side being the bottom, and the horizontal direction (side) relative to the vertical direction, but these do not represent universal vertical and horizontal directions.

In addition, deviations are permitted in directions such as parallel, right-angled, orthogonal, horizontal, vertical, up-down, left-right, etc., to the extent that they do not impair the effects of the disclosure in the embodiments. Furthermore, the X direction, Y direction, and Z direction represent directions parallel to the X axis, directions parallel to the Y axis, and directions parallel to the Z axis, respectively. The X, Y, and Z directions are perpendicular to one another. The XY plane, YZ plane, and ZX plane represent imaginary planes parallel to the X and Y directions, imaginary planes parallel to the Y and Z directions, and imaginary planes parallel to the Z and X directions, respectively. The X axis, Y axis, and Z axis are examples of the first axis, second axis, and third axis, respectively, and the X direction, Y direction, and Z direction are examples of the first axis direction, second axis direction, and third axis direction, respectively.

Electronic device 200 is, for example, an information processing terminal such as a smartphone, tablet computer, or notebook PC (Personal Computer). Electronic device 200 is not limited to these, and may also be, for example, a structure such as a pillar or wall, digital signage, an electronic device including a display panel inside a train, or an electronic device including various display panels inside a vehicle.

As shown in Figures 1 and 2, a display module D capable of displaying information is disposed on the entire top surface of the electronic device 200, or at least a portion of the top surface. The antenna device 100 is disposed above a touch panel 230 on a display panel 220. The upper side of the antenna device 100 is visible from outside the electronic device 200 through a transparent cover 240, which is transparent so that the display panel 220 can be seen from the outside through the antenna device 100. The display panel 220 is an example of a display device. The display surface of the display panel 220 is the surface on the +Z direction side of the display panel 220.

Referring to FIG. 2, in the electronic device 200, the display panel 220, touch panel 230, antenna device 100, and transparent cover 240 are collectively referred to as a display module D (also referred to as a display module).

In addition to the display module D, the electronic device 200 includes a housing 210, a wiring board 250, electronic components 260A, 260B, 260C, and 260D, a battery 270, etc.

In Figures 1 and 2, an example is shown in which the electronic device 200 in which the antenna device 100 is mounted is a smartphone, but the electronic device in which the antenna device 100 is mounted may have other configurations as long as it includes a housing 210, a transparent cover 240, and a display panel 220. Furthermore, the electronic device 200 may not be equipped with a touch panel 230.

The housing 210 is a case made of, for example, metal and/or resin, and covers the bottom and side surfaces of the electronic device 200. The housing 210 has an opening edge 211 that forms the upper end of the peripheral wall, and a transparent cover 240 is attached to the opening edge 211. The housing 210 has a storage section 212, which is an internal space that communicates with the opening edge 211, and the storage section 212 stores a wiring board 250, electronic components 260A-260D, a battery 270, etc.

Transparent cover 240, an example of a cover glass, is a transparent glass plate provided on the top surface and has a size that matches the open edge 211 of housing 210 in a plan view. In this example, transparent cover 240 is an example of a glass plate that is mostly flat and has both ends in the horizontal direction (±Y direction) that curve gently downward, but it may also be a glass plate that is flat in the horizontal direction. Alternatively, transparent cover 240 may also have both ends in the vertical direction (±X direction) of electronic device 200 that curve gently downward. Here, a form in which transparent cover 240 is made of glass is described, but transparent cover 240 may also be made of resin.

The transparent cover 240 is attached to the open end 211 of the housing 210, sealing the storage section 212 of the housing 210.

The upper surface of the transparent cover 240 is an example of the outer surface of the transparent cover 240, and the lower surface of the transparent cover 240 is an example of the inner surface of the transparent cover 240. The antenna device 100 and touch panel 230 are provided on the inner surface side of the transparent cover 240. Because the transparent cover 240 is transparent, the touch panel 230 and display panel 220 provided inside can be seen through the transparent cover 240 from outside the electronic device 200.

Electronic components 260A-260C are mounted on wiring board 250. Power feed lines (shown by dotted lines in Figure 2) extending from power feed line 120 of the antenna device (see Figure 5) are connected to wiring board 250. Wiring board 250 and power feed line 120 of antenna device 100 may be connected using a connector, an anisotropic conductive film (ACF), or other components.

As an example, electronic component 260A is a communications module that is connected to the power supply line 120 of the antenna device 100 via wiring on the wiring board 250 and processes signals transmitted or received via the antenna device 100. Furthermore, the central electronic component 260B is, for example, a camera.

Electronic components 260C and 260D are, for example, components that perform information processing related to the operation of electronic device 200, and are realized by a computer that includes, for example, a CPU (Central Processing Unit), RAM (Random Access Memory), ROM (Read Only Memory), HDD (Hard Disk Drive), an input/output interface, and an internal bus.

Battery 270 is a rechargeable secondary battery that supplies the power necessary to operate display module D and electronic components 260A-260D, etc.

<Display Module D>
Next, a description will be given of the position of the antenna device 100 in the display module D. FIG.

Although not shown in Figure 2, the display module D has a polarizer 280 between the touch panel 230 and the transparent cover 240, as shown in Figure 3. Also, although shown as a single component in Figure 2, the antenna device 100 is composed of two substrates, a first transparent substrate 101 and a second transparent substrate 102, sandwiching the polarizer 280. The first transparent substrate 101 is an example of a first insulator substrate, and the second transparent substrate 102 is an example of a second insulator substrate. The top surface (the surface on the +Z direction side) of the first transparent substrate 101 is an example of a front surface. The second transparent substrate 102 is provided closer to the display panel 220 than the first transparent substrate 101.

The adhesive layers are provided from top to bottom as a first adhesive layer 291, a second adhesive layer 292, a third adhesive layer 293, and a fourth adhesive layer 294. The first adhesive layer 291 to the fourth adhesive layer 294 are made of a transparent optical adhesive called OCA (Optical Clear Adhesive).

In Figure 3, the touch panel 230 is shown as an example of a "metallic thin line layer for an on-cell touch panel" formed directly on the surface of the display panel 220 without an adhesive layer. However, an adhesive layer may also be provided between the touch panel 230 and the display panel 220.

Note that although Figures 2 and 3 show an example in which a touch panel 230 is provided in the display module D, the display module D installed in the electronic device 200 does not necessarily have to be equipped with a touch panel 230.

The display panel 220 is, for example, a liquid crystal display panel, an organic EL (electroluminescence) display panel, or an OLED (organic light emitting diode) display panel, and in either configuration, it is positioned at the bottom of the display module D.

In addition, since the antenna device 100 is provided partially in the display module D as shown in FIG. 1, the touch panel 230, polarizing plate 280, and/or first to fourth adhesive layers 291-294 may be made thinner in the area where the antenna device 100 is provided than in other areas, or the polarizing plate 280 and/or first to fourth adhesive layers 291-294 may not be provided. This makes it possible to prevent only the area of the antenna device 100 from being raised in the display module D.

Furthermore, if the antenna device 100 is too thick, the edges of the antenna device 100 may become visible, and air may easily become trapped at the boundaries with the first to fourth adhesive layers 291 to 294. The thicknesses of the first transparent substrate 101 and second transparent substrate 102 of the antenna device 100 are preferably 300 μm or less, more preferably 150 μm or less, and particularly preferably 100 μm or less. Furthermore, from the perspective of ease of handling, the thicknesses of the transparent substrates 101 and 102 of the antenna device 100 are preferably 10 μm or more, and more preferably 50 μm or more.

Furthermore, in the antenna device 100, the first transparent substrate 101 and the second transparent substrate 102 may have different substrate sizes in the ±X and ±Y directions. Furthermore, the transparent substrates 101 and 102 that make up the antenna device 100 may have the same or different substrate thicknesses. However, if they are different, it is preferable that the thickness t1 of the first transparent substrate 101 be less than the thickness t2 of the second transparent substrate 102.

Furthermore, as will be described later, in the antenna device 100, the first transparent substrate 101 and the second transparent substrate 102 are not connected by wiring but are connected via AC. The second adhesive layer 292, the polarizing plate 280, and the third adhesive layer 293 function as dielectrics sandwiched between the first transparent substrate 101 and the second transparent substrate 102. It is preferable that the dielectric constant ε of the second adhesive layer 292, the polarizing plate 280, and the third adhesive layer 293 be within a range between the dielectric constant ε1 of the first transparent substrate 101 and the dielectric constant ε2 of the second transparent substrate 102.

In addition, while Figures 1 and 2 show an example in which the display module D has gently curved ends in the ±Y direction, the display module D may have a flat shape with no curved ends. In that case, the antenna device 100 may also have a flat shape. Note that if the antenna device 100 has a partially curved surface, the transmission area, which will be described later, will have a curved shape.

<Configuration example of antenna device>
Next, an example of the configuration of the antenna device 100 will be described using FIGS. 4 to 6 in addition to FIG. 3 . FIG. 4 is a perspective view showing an example of the configuration of the antenna device 100. FIG. 5 is a view showing an example of an exploded state of the antenna device 100. FIG. 5A is a top view of the first transparent substrate 101 as seen from the +Z direction, and FIG. 5B is a bottom view of the first transparent substrate 101 as seen from the −Z direction. FIG. 5C is a top view of the second transparent substrate 102 as seen from the +Z direction, and FIG. 5D is a bottom view of the second transparent substrate 102 as seen from the −Z direction. Note that even when a portion of the antenna device 100 is arranged along a curve as in FIG. 1 , FIG. 4 shows the antenna device 100 in a state parallel to the XY plane before it is bent.

The antenna device 100 has an antenna element 110 and a feed line 120 provided on the upper surface (front surface) of a first transparent substrate 101. The antenna element 110 is an example of a patch-type antenna. A ground layer 130 is provided on the lower surface (back surface) of a second transparent substrate 102. The antenna element 110 and the feed line 120 may also be provided on the lower surface of the first transparent substrate 101.

As shown in Figure 3, a second adhesive layer 292, a polarizing plate 280, and a third adhesive layer 293 are provided between the first transparent substrate 101 and the second transparent substrate 102. The distance ds between the first transparent substrate 101 and the second transparent substrate 102 shown in Figure 4 is approximately 150 μm.

Furthermore, as shown in FIG. 4, the antenna element 110 is provided on the upper surface of the first transparent substrate 101, and the ground layer 130 is provided on the lower surface of the second transparent substrate 102. The distance dm between the antenna element 110 and the ground layer 130 is approximately 500 μm. The distance dm is 100 μm or more, preferably 200 μm or more, and more preferably 300 μm or more.

As shown in FIG. 3, the second transparent substrate 102 is disposed directly above the touch panel 230 or display panel 220, with an adhesive layer 294 sandwiched between them. Therefore, it is preferable that the retardation δ2, which is the product (Δnd) of the refractive index difference (Δn) with respect to the polarization direction and the thickness (d) of the substrate, be low. On the other hand, since the first transparent substrate 101 is separated from the touch panel 230 or display panel 220, the retardation δ1 does not need to be low. Therefore, it is preferable that the retardations of the first transparent substrate 101 and the second transparent substrate 102 have a relationship of δ1≧δ2, and may be δ1>δ2.

To satisfy the above retardation requirements, the first transparent substrate 101 is made of PET (polyethylene terephthalate resin) or COP (cycloolefin polymer), and the second transparent substrate 102 is made of, for example, COP. For example, the retardation of PET is 5061.7 nm at a thickness of 100 μm, and the retardation of COP is 3.77 nm at a thickness of 100 μm.

As mentioned above, for the same thickness, retardation is a value that increases or decreases depending on the birefringence caused by the substrate material, and is an amount that affects image clarity, etc. Therefore, retardation is evaluated using light in the visible light range (wavelengths 380nm to 780nm).

On the other hand, the dielectric constant is a quantity related to the antenna characteristics. Therefore, the dielectric constant is evaluated within the wavelength range of the radio waves being used. It is preferable that the dielectric constant ε2 of the second transparent substrate 102 is lower than the dielectric constant ε1 of the first transparent substrate 101. With a low ε2, the pitch between the thin metal wires of the ground layer 130 becomes relatively narrow in terms of electrical length, thereby suppressing leakage of radio waves from the ground layer 130 downward. For example, the dielectric constant of the PET that makes up the first transparent substrate 101 is 3.31 at 35 GHz, and the dielectric constant of the COP that makes up the second transparent substrate 102 is 2.31 at 35 GHz.

Furthermore, to ensure that the antenna device 100 is colorless and transparent, it is preferable that the transmittance of each substrate 101, 102 be 80% or higher, and both transparent substrates 101, 102 are flexible substrates that can be bent in the Z direction and/or X direction.

The antenna element 110 is a patch-type antenna element located near the center of the first transparent substrate 101 in the X direction. The antenna element 110 is rectangular in plan view and has a power supply portion 111 and a recess 112.

The recess 112 is a recess in the +Y direction at the center of the edge of the antenna element 110 extending in the X direction on the -Y direction side, and the power supply part 111 is located in the center of the recess 112 in the X direction. The power supply part 111 is connected to the signal line 121B of the power supply line 120, and the recess 112 is divided into the +X direction side and the -X direction side by the signal line 121B.

The antenna element 110 is provided on the upper surface of the first transparent substrate 101. The recess 112 is provided to match the radiation resistance, which is determined by the thickness and dielectric constant of the surrounding materials of the antenna element 110 and the patch element size, with the feed line impedance.

Here, the length of the antenna element 110 in the X direction is defined as X110, and the effective length in the Y direction is defined as Y110. X110 is the overall length of the antenna element 110 in the X direction, and Y110 is the length from the end of the antenna element 110 on the +Y direction side to the power supply part 111. Since the antenna element 110 is excited in the Y direction, Y110 is the effective length of the antenna element 110 in the excitation direction.

If the wavelength on the first transparent substrate 101 at the resonant frequency f1 (28 GHz) of the antenna device 100 is λ (electrical length), Y110 is set to an integer multiple of approximately 0.5λ, and X110 is set to a value smaller than 1.0λ. Therefore, if you wish to improve the antenna gain at the resonant frequency f1, it is recommended that X110 and Y110, which define the size of the antenna element 110, be adjusted to within ±10% of approximately 2.5 mm each.

The feed line 120 is also arranged at the longitudinal end (-Y direction end) of the first transparent substrate 101. As an example, the feed line 120 has a coplanar waveguide (CPW) section and a microstrip line (MSL) section. The feed line 120 has a signal line 121 that extends on the upper surface of the first transparent substrate 101 at the center of the first transparent substrate 101 in the X direction, and planar ground portions 122 and 123 that sandwich the signal line 121 in the X direction.

The signal line 121 has a signal line 121A on the -Y direction side and a signal line 121B on the +Y direction side. Signal line 121A is the portion of the signal line 121 on the -Y direction side, and signal line 121B is the portion of the signal line 121 on the +Y direction side. End 121A1 on the -Y direction side of the signal line 121 is located near an edge extending in the X direction on the -Y direction side of the first transparent substrate 101 and is an example of a first end. End 121B1 on the +Y direction side of the signal line 121B is an example of a second end. End 121B1 is connected to the power supply 111 of the antenna element 110.

Signal line 121A is the portion sandwiched between ground sections 122 and 123 that forms the coplanar waveguide, while signal line 121B is the portion that forms the MLS. Signal line 121B forms a microstrip line by overlapping with ground layer 130 on the underside of second transparent substrate 102. Note that because ground layer 130 is provided over the entire underside of second transparent substrate 102, signal line 121A of signal line 121 also overlaps with ground layer 130.

In this configuration example, the signal line 121 and ground sections 122 and 123 that make up the power supply line 120 are all provided on the upper surface of the first transparent substrate 101.

When the antenna device 100 is incorporated into the electronic device 200, the signal line 121 of the power feed line 120 is electrically connected to the wiring board 250 and the electronic component 260A, which is a communication circuit, and power is supplied to them. While FIG. 4 shows an example in which the power feed line 120 is provided approximately halfway in the Y direction from the end on the -Y direction side, the power feed line 120 may also be provided approximately one-quarter to three-quarters of the way along the -Y direction side. Furthermore, the first transparent substrate 101 may have a portion that extends further in the -Y direction, and a signal line that is positioned further in the -Y direction than the signal line 121 and is made of metal foil or the like rather than a metal mesh may be connected to the end 121A1 on the -Y direction side of the signal line 121.

In addition, while Figure 4 illustrates an example in which the end of the power supply line 120 extends to the end (-Y side end) of the first transparent substrate 101, part or all of the power supply line 120 may be located outside the periphery of the first transparent substrate 101. Furthermore, by forming the power supply line 120 to be flexible, the power supply line 120 may be able to wrap around the side edge or back surface of the display module D and be electrically connected on the side or back surface.

On the other hand, on the second transparent substrate 102 on the lower side of the antenna device 100, the ground layer 130 is provided over the entire lower surface of the second transparent substrate 102.

It is preferable that the ground layer 130 covers at least the entire area of the antenna element 110 on the +Y side, and is positioned with a margin of +2.5 mm in the Y direction and 2.5 mm in the X direction relative to the end of the antenna element 110.

Figures 4 and 5 show an example configuration in which the first transparent substrate 101 and the second transparent substrate 102 have the same vertical and horizontal sizes (X101 = X102, Y101 = Y102) and are completely overlapped in the vertical direction, but the first transparent substrate 101 and the second transparent substrate 102 may have different vertical and horizontal sizes, or may only partially overlap in a planar view. If the first transparent substrate 101 and the second transparent substrate 102 are misaligned in size or position, it is sufficient that the ground layer 130 of the second substrate 102 overlaps with the antenna element 110 and the ground sections 122 and 123 of the feeder line 120 at least in the X and Y directions.

Here, the antenna element 110, feed line 120, and ground layer 130 shown in mesh form in Figures 4 and 5 are composed of the transparent conductor 30 shown in Figure 6.

<Transparent conductor (thin metal wire layer) of antenna device>
Fig. 6 is a diagram showing an example of the configuration of the transparent conductor 30 of the antenna device 100. The transparent conductor 30 is formed on the outermost surfaces of the first transparent substrate 101 and the second transparent substrate 102, and is used to form, for example, the antenna element 110, the feed line 120, and the ground layer 130 shown in Fig. 4 and Fig. 5. The transparent conductor 30 is a conductor with such high optical transparency that it is difficult for the human eye to see.

The transparent conductor 30 is a layer of conductive lines, for example, formed in a mesh shape to enhance light transmittance, and is a thin metal wire layer. As shown in Figure 6, the mesh-like thin metal wire layer that makes up the transparent conductor 30 is arranged so that multiple thin metal wires 31 extending in one direction intersect with multiple thin metal wires 32 extending in the other direction, leaving openings (through holes) 33 that are mesh-like gaps (openings).

When the transparent conductor 30 is formed in a mesh shape, the openings 33 of the mesh may be diamond-shaped or any polygonal shape other than diamond-shaped, but here we will explain a case where the openings 33 are diamond-shaped. The transparent conductor 30 has multiple openings 33, and all of the multiple openings 33 basically need to be the same shape, but the shapes of the openings 33 at the outer edges of the antenna element 110, feed line 120, or ground layer 130 do not need to be the same. Figure 6 shows a portion where the openings 33 are all the same shape.

The transparent conductor 30 includes a plurality of cells 30A. Each cell 30A has one opening 33. The plurality of cells 30A included in the transparent conductor 30 all have the same shape, and in this example, the length Y30A in the Y direction is longer than the length X30A in the X direction. The length X30A in the X direction is an example of a first length in the first axis direction, and the length Y30A in the Y direction is an example of a second length in the second axis direction. The Y direction is the longitudinal direction of the cell 30A. The reason why the length Y30A in the Y direction is longer than the length X30A in the X direction will be described later using Figure 7.

The pixels of the display panel 220 are arranged along the X and Y directions. The extension direction of the thin metal wires 31 and 32 is angled relative to the X and Y directions, and is therefore oblique to the X and Y directions. Here, the extension direction of the thin metal wires 31 and 32 being angled relative to the X and Y directions means that the angle is greater than 0 degrees in absolute value. Moiré can be suppressed by having the extension direction of the thin metal wires 31 and 32 be angled relative to the pixel arrangement direction of the display panel 220. Note that at the outer edges of the antenna element 110, the feed line 120, or the ground layer 130, there may be portions where the thin metal wires 31 or 32 are parallel to the pixel arrangement direction of the display panel 220.

The line widths w31 and w32 of the fine metal wires 31 and 32 that make up the mesh are preferably 1 to 10 μm, and more preferably 1 to 5 μm. The line widths w31 and w32 are the widths in a direction perpendicular to the extension direction of the fine metal wires 31 and 32 in a planar view. Furthermore, the length X30A of the cell 30A in the X direction is preferably 50 μm to 500 μm, and more preferably 100 μm to 400 μm. Here, as an example, X30A is set to 100 μm. Furthermore, the length Y30A of the cell 30A in the Y direction is preferably 50 μm to 500 μm, and more preferably 100 μm to 400 μm. Here, as an example, Y30A is set to 200 μm.

The aperture ratio, which is the ratio of the area of the openings 33 to the entire mesh in the transparent conductor 30, is preferably 80% or more, and more preferably 90% or more. The higher the aperture ratio of the transparent conductor 30, the higher the visible light transmittance of the transparent conductor 30 can be.

When the transparent conductor 30 is formed in a mesh shape, the thickness of the transparent conductor 30 may be 1 to 40 μm. By forming the transparent conductor 30 in a mesh shape, it is possible to increase the visible light transmittance even if the transparent conductor 30 is thick. The thickness of the transparent conductor 30 is more preferably 5 μm or more, and even more preferably 8 μm or more. Furthermore, the thickness of the transparent conductor 30 is more preferably 30 μm or less, even more preferably 20 μm or less, and particularly preferably 15 μm or less.

In the transparent conductor 30, the thickness (thickness in the Z direction) of the metal thin wires 31, 32 is set smaller than the line width (conductor width) w31, w32 of the mesh-like metal thin wires 31, 32. This is because an aspect ratio greater than 1 results in structural imbalance, making the structure more susceptible to breakage and difficult to manufacture. However, the thicker the metal thin wires 31, 32, the lower the sheet resistance value, so in terms of antenna efficiency, it is better for the metal thin wires 31, 32 to be thicker. For this reason, it is preferable for the thickness of the metal thin wires 31, 32 to be smaller than the line width (conductor width) w31, w32 of the metal thin wires 31, 32, and as large as possible.

The conductive material for the thin metal wires 31, 32 of the transparent conductor 30 can be copper, but other metal materials such as silver, aluminum, chromium, nickel, gold, platinum, tin, and iron can also be used, and the material is not limited to these.

The antenna element 110, feed line 120, and ground layer 130 realized with such transparent conductors 30 are transparent, have high optical transparency so that they are difficult to see with human eyesight, and can function as conductors. Furthermore, the transparent conductors 30 that make up these thin metal wire layers have a surface resistance of, for example, 5 Ω/sq or less, more preferably 1 Ω/sq or less, and even more preferably around 0.5 Ω/sq.

As shown in FIG. 3, the first transparent substrate 101 on the upper side of the antenna device 100 is located closer to the surface than the polarizing plate 280. Therefore, it is preferable to subject the thin metal wire layer that constitutes the antenna element 110 and the feed line 120 formed on the first transparent substrate 101 to a blackening treatment, which makes it less likely to reflect visible light. In the blackening treatment, the surface of the thin metal wire is coated with a material containing copper oxide (CuO) or copper nitride (CuN). Note that this treatment is not required for the thin metal wires of the ground layer 130, which is the thin metal wire layer of the second transparent substrate 102 that is located on the inner side than the polarizing plate 280.

<Reason why the length Y30A in the Y direction is longer than the length X30A in the X direction>
7 is an exemplary diagram illustrating why the length Y30A in the Y direction is longer than the length X30A in the X direction. A current flows in the Y direction in the signal line 121. In other words, the signal transmission direction in the signal line 121 is the Y direction. The excitation direction of the antenna element 110 is also the Y direction. Furthermore, since a current flows in the ground layer 130 in the Y direction, the signal transmission direction in the ground layer 130 is also the Y direction.

When the Y-direction length Y30A of cell 30A is longer than the X-direction length X30A, the equivalent impedance of the antenna element 110, feed line 120, and ground layer 130 in the Y direction is lowered, making it easier for current to flow and increasing the radiation efficiency of the antenna device 100. Increasing the radiation efficiency of the antenna device 100 increases the gain of the antenna device 100. In particular, it has been found that when the Y-direction length Y30A of cell 30A is longer than the X-direction length X30A in the signal line 121 of the feed line 120, the radiation efficiency of the antenna device 100 increases and the gain increases. This is thought to be because the length of the thin metal wires 31, 32 in the Y direction is shorter in a transparent conductor 30 in which cells 30A with square openings 33 with a length X30A of 100 μm and a length Y30A of 200 μm are arranged than in a transparent conductor in which cells with square openings with lengths X30A and Y30A of 100 μm are arranged.

For this reason, in the antenna device 100, the Y-direction length Y30A of the cell 30A of the transparent conductor 30 that constitutes the antenna element 110, the feed line 120, and the ground layer 130 is set longer than the X-direction length X30A.

In addition, in FIG. 7, the distance D1 between the -Y end of the antenna element 110 and the +Y end of the ground portions 122 and 123 is, for example, 500 μm. The distance D2 between the -Y end of the antenna element 110 and the +Y end of the recess 112 is, for example, 210 μm. Therefore, the length of the signal line 121B in the Y direction is, for example, 710 μm. The distance D3 on the X side of the recess 112 is, for example, 200 μm.

Furthermore, thin metal wires extend in the X and Y directions at the outer edges of the antenna element 110, the feed line 120, and the ground layer 130. In this way, at the outer edges of the antenna element 110, the feed line 120, and the ground layer 130, there may be portions where the thin metal wires are parallel to the pixel arrangement direction of the display panel 220. This is because, when viewed as a whole, these outer edges are only a small portion of the display panel 220.

In addition, since the X-direction length X30A and the Y-direction length Y30A of cell 30A are different, irregularities occur in the X and Y directions, which makes it possible to more effectively suppress moire.

In addition, since the antenna element 110 and the feed line 120 overlap with the ground layer 130, for example, the size of the cells 30A of the transparent conductor 30 of the antenna element 110 and the feed line 120 is the same as that of the cells 30A of the transparent conductor 30 of the ground layer 130, and the positions of the cells 30A in the X and Y directions are the same. This is to more effectively suppress moire.

Also, as an example, the X-direction length X30A of cell 30A is different from the pixel pitch in the X direction of display panel 220 (an example of a first pitch), and the Y-direction length Y30A is different from the pixel pitch in the Y direction of display panel 220 (an example of a second pitch). This is to more effectively suppress moiré. Also, as an example, cell 30A is arranged so that the boundaries of cell 30A in the X and Y directions do not overlap as much as possible with the boundaries between pixels in the X and Y directions of display panel 220. This is to more effectively suppress moiré.

In addition, the ratio of the Y-direction length Y30A to the X-direction length X30A of cell 30A is 2 (200 μm/100 μm) here as an example, but from the perspective of suppressing moiré and improving radiation efficiency, the ratio Y30A/X30A is preferably in the range of 1.2 to 5.0, and more preferably in the range of 1.5 to 3. Furthermore, it is even more preferable that the ratio Y30A/X30A be 2 or greater.

Furthermore, the ratio of the X-direction length X30A of cell 30A to the pixel pitch in the X direction of display panel 220 (an example of a first pitch) is preferably within the range of 0.5 to 2.3. Furthermore, the ratio of the Y-direction length Y30A of cell 30A to the pixel pitch in the Y direction (an example of a second pitch) is preferably within the range of 1.2 to 4.0. Furthermore, the ratio Y30A/X30A is preferably greater than the ratio of the pixel pitch in the Y direction to the pixel pitch in the X direction of display panel 220, and more preferably 1.5 times or more.

<Characteristics of Antenna Device 100>
Fig. 8 is a diagram showing an example of the frequency characteristic of the S11 parameter of the antenna device 100. The S11 parameter shown in Fig. 8 is the ratio of the power reflected back to the power feeding unit 111 to the power input to the power feeding unit 111, and is obtained by electromagnetic field simulation.

As an example, when examining the value at -10 dB, it was found to be below -10 dB in the frequency band from approximately 26.8 GHz to approximately 29.7 GHz, confirming that good radiation efficiency was achieved in the frequency band including the resonant frequency f1 (28 GHz) of the antenna device 100. This is thought to be due to the fact that the longitudinal direction of the cell 30A is aligned with the signal transmission direction in the feed line 120 and ground layer 130, and that the longitudinal direction of the cell 30A is aligned with the excitation direction of the antenna element 110, thereby increasing the radiation efficiency of the antenna device 100 and increasing the gain.

Figure 9 is a diagram showing an example of the directivity of the antenna device 100 in the YZ plane. The directivity shown in Figure 9 was obtained through electromagnetic field simulation. The 90-degree direction is the +Y direction, the 0-degree direction is the +Z direction, and the -90-degree direction is the -Y direction. As shown in Figure 9, it was confirmed that uniform, upward directivity was obtained in the YZ plane. The good directivity is thought to be the result of increased gain due to the increased radiation efficiency of the antenna device 100.

Figure 10 shows an example of the relationship between the cell shape of the transparent conductor 30 and the efficiency and peak gain. For comparison, the efficiency and peak gain were determined by electromagnetic field simulation using a transparent conductor with a square cell shape and a diamond-shaped transparent conductor elongated in the X direction. The cell shape is the opening shape of the cell.

For the transparent conductor consisting of a square cell, the length of the cell in the X direction was 100 μm, the length in the Y direction was 100 μm, and the line width was 6 μm. The square cell is a cell in which the thin metal lines extend at 45 degrees to the X and Y directions. The efficiency was 59.1%, and the peak gain was 3.85 dB.

For the transparent conductor consisting of cells long in the X direction, the length of the cells in the X direction was 200 μm, the length in the Y direction was 100 μm, and the line width was 6 μm. The cell long in the X direction was a cell configured by rotating cell 30A shown in Figure 6 by 90 degrees clockwise in a plan view. The efficiency was 50.5%, and the peak gain was 3.04 dB, both of which were lower than those of square cells.

For the transparent conductor 30 composed of cell 30A, the cell's length in the X direction was 100 μm, its length in the Y direction was 200 μm, and its line width was 6 μm. The efficiency was 62.8%, and the peak gain was 4.03 dB, both of which were higher than those of a square cell.

<Effects>
As described above, the Y-direction length Y30A of the cell 30A of the transparent conductor 30 constituting the antenna element 110, the feed line 120, and the ground layer 130 is set to be longer than the X-direction length X30A, and the signal line 121A on the -Y-direction side of the signal line 121 of the feed line 120 extends in the Y direction. This increases the radiation efficiency of the antenna device 100, thereby increasing the gain. Furthermore, by setting the Y-direction length Y30A of the cell 30A to be longer than the X-direction length X30A, moire can be suppressed.

Therefore, it is possible to provide an antenna device 100 and electronic device 200 that are realized using a metal mesh and are capable of both suppressing moiré and improving antenna characteristics. In particular, by making the Y-direction length Y30A of cell 30A longer than the X-direction length X30A in the signal line 121 of the feed line 120, the equivalent impedance is reduced, making it easier for current to flow, and resulting in increased radiation efficiency and gain for the antenna device 100.

Furthermore, the pitch of the pixels of the display panel 220 in the X direction is different from the length X30A of the cells 30A, and the pitch of the pixels of the display panel 220 in the Y direction is different from the length Y30A of the cells 30A, so moire can be more effectively suppressed.

Furthermore, it is preferable that the ratio (Y30A/X30A) of the length Y30A to the length X30A of the cell 30A be 2 or greater. By reducing the sheet resistance in the propagation direction of the high-frequency current (Y direction), it is possible to achieve both reduced losses in the feed line 120 and improved antenna efficiency.

Furthermore, it is preferable that the ratio of length Y30A to length X30A (Y30A/X30A) be greater than the ratio of the pitch in the Y direction to the pitch in the X direction of the pixels of the display panel 220. From the perspective of reducing moiré, it is more preferable that the ratio Y30A/X30A be 1.5 times or more the ratio of the pitch in the Y direction to the pitch in the X direction of the pixels of the display panel 220.

In addition, the aperture ratio of the metal mesh of the antenna element 110, the feed line 120, and the ground layer 130 is 80% or more, making it possible to realize an antenna device 100 that is difficult to see and is colorless and transparent.

Furthermore, because the mesh is diamond-shaped, it is easy to create cells 30A whose Y-direction length Y30A and X-direction length X30A are different, making it possible to provide an antenna device 100 and electronic device 200 that can more reliably suppress moiré and improve antenna characteristics at the same time.

The signal line 121 of the feeder line 120 extends in the Y direction from end 121A1 to end 121B1, which facilitates current flow and increases the radiation efficiency of the antenna device 100. This makes it possible to provide an antenna device 100 and electronic device 200 with improved antenna characteristics.

Furthermore, because the excitation direction of the antenna element 110 is along the Y direction, current flows more easily through the antenna element 110, further increasing the radiation efficiency of the antenna device 100. This makes it possible to provide an antenna device 100 and electronic device 200 with further improved antenna characteristics.

The antenna element 110 is a patch antenna, monopole, or dipole antenna, so the antenna device 100 and electronic device 200 can be provided with a simple antenna element 110 that can both suppress moiré and improve antenna characteristics.

Furthermore, since the feed line 120 is a coplanar line or a microstrip line, it is possible to provide an antenna device 100 and electronic device 200 that can simultaneously suppress moiré and improve antenna characteristics using a feed line 120 with a simple configuration.

The antenna device 100 also includes a second transparent substrate 102 provided on the -Z direction side of the first transparent substrate 101 and a ground layer 130 provided on the second transparent substrate 102, and signal line 121B of the signal line 121 of the feeder line 120 forms a microstrip line. Therefore, impedance matching with the antenna element 110 can be achieved even in signal line 121B of the signal line 121, which is located on the +Y direction side of the end edge extending in the X direction on the +Y direction side of the ground portions 122, 123, thereby providing an antenna device 100 and electronic device 200 that not only suppresses moiré but also further improves antenna characteristics.

Note that the signal line 121 only needs to extend in the Y direction from the end on the -Y direction side, at least on the side including the end on the -Y direction side. Therefore, for example, the signal line 121 may be bent in the +X direction or the -X direction on the side closer to the power supply unit 111. In this case, the excitation direction of the antenna element 110 may be the X direction.

Furthermore, the antenna element 110 is not limited to a patch type, but may also be a monopole type or a dipole type. In particular, in the case of a dipole type, the signal line 121 may be bent in the +X direction or the -X direction on the side closer to the power supply portion 111.

<Modification>
11A and 11B are diagrams showing an example of the configuration of cells 30MA1 and 30MA2 according to a modified example of the embodiment. The cell 30MA1 shown in Fig. 11A and the cell 30MA2 shown in Fig. 11B are cells that can be arranged on the transparent conductor 30 in place of the cell 30A shown in Fig. 6.

The cell 30MA1 shown in Figure 11A is configured by rotating an isosceles triangle in a plan view so that its three sides form angles with respect to the X-axis and Y-axis. The X-direction length X30MA1 of such cell 30MA1 is the length between the end of cell 30MA1 on the -X-direction side and the end on the +X-direction side, and the length Y30MA1 is the length between the end of cell 30MA1 on the -Y-direction side and the end on the +Y-direction side. The ±X-direction and ±Y-direction side ends of cell 30MA1 are located at the center of the width of the thin metal wire of cell 30MA1. The length Y30MA1 is longer than the length X30MA1.

The cell 30MA2 shown in Figure 11B is configured by rotating a hexagon in a planar view so that its six sides form angles with respect to the X-axis and Y-axis. The X-direction length X30MA2 of such a cell 30MA2 is the length between the end of the cell 30MA2 on the -X-direction side and the end on the +X-direction side, and the length Y30MA2 is the length between the end of the cell 30MA2 on the -Y-direction side and the end on the +Y-direction side. The ends of the cell 30MA2 on the ±X-direction side and ±Y-direction side are located at the center of the width of the thin metal wire of the cell 30MA2. The length Y30MA2 is longer than the length X30MA2.

Cells 30MA1 and 30MA2 are polygonal cells other than a rhombus. Here, isosceles triangular and hexagonal cells 30MA1 and 30MA2 are shown as examples, but polygonal cells other than a rhombus may also be pentagonal, heptagonal, or polygonal with eight or more sides, as long as their length in the Y direction is longer than their length in the X direction.

The above describes exemplary antenna devices and electronic devices according to the present disclosure, but the present disclosure is not limited to the specifically disclosed embodiments, and various modifications and variations are possible without departing from the scope of the claims.

30 Transparent conductor 30A, 30MA1, 30MA2 Cell 31, 32 Thin metal wire 33 Opening 100 Antenna device 101 First transparent substrate (an example of a first insulating substrate)
102 Second transparent substrate (an example of a second insulating substrate)
110 Antenna element 111 Power supply portion 112 Recess 120 Power supply line 121, 121A, 121B Signal line 121A1 End portion (an example of a first end portion)
121B1 End (an example of a second end)
122, 123 Ground section 130 Ground layer 200 Electronic device

Claims (11)

a first insulating substrate;
an antenna element formed of a metal mesh and provided on a surface of the first insulating substrate;
a feeder line formed of a metal mesh and provided on the surface of the first insulator substrate, the feeder line extending between a first end and a second end connected to a feed portion of the antenna element;
the feed line extends from the first end in the second axial direction relative to a first axis and a second axis that are included in the surface and are perpendicular to each other;
the first insulating substrate is provided on a display surface side of a display device,
The plurality of pixels included in the display device are arranged along the first axis direction and the second axis direction,
the metal mesh of the antenna element and the feed line includes a plurality of cells each having a first length in the first axis direction and a second length in the second axis direction;
an extending direction of the thin metal wires constituting the plurality of cells has an angle with respect to the first axis direction and the second axis direction;
the second length is longer than the first length,
An antenna device, wherein a first pitch of the plurality of pixels in the first axis direction is different from the first length, and a second pitch of the plurality of pixels in the second axis direction is different from the second length . 2. The antenna device according to claim 1 , wherein a ratio of the second length to the first length is in a range of 1.2 to 5.0. 2. The antenna device according to claim 1 , wherein a ratio of the second length to the first length is equal to or greater than 1.5 times a ratio of the second pitch to the first pitch. 2. The antenna device according to claim 1 , wherein a ratio of the first length to the first pitch is in a range of 0.5 to 2.3, and a ratio of the second length to the second pitch is in a range of 1.2 to 4.0. 5. The antenna device according to claim 1 , wherein the opening ratio of the metal mesh of the antenna element and the feeder line is 80% or more. The antenna device according to claim 1 , wherein the cells are rhombic or polygonal other than rhombic. The antenna device according to claim 1 , wherein the feed line extends along the second axis direction from the first end to the second end. The antenna device according to claim 1 , wherein an excitation direction of the antenna element is along the second axis direction. the antenna element is a patch antenna, a monopole, or a dipole antenna;
When the antenna element is the patch antenna,
a second insulating substrate provided closer to the display device than the first insulating substrate;
a ground layer provided on the second insulating substrate;
9. The antenna device according to claim 1 , further comprising : the feed line is a coplanar line or a microstrip line,
When the feed line is a microstrip line,
a second insulating substrate provided closer to the display device than the first insulating substrate;
a ground layer provided on the second insulating substrate;
further comprising
The antenna device according to claim 1 , wherein a portion of the feed line that overlaps with the ground layer constitutes the microstrip line . a display device;
an antenna device provided on a display surface side of the display device,
the display device is a liquid crystal display or an organic light emitting diode;
The antenna device includes:
a first insulating substrate;
an antenna element formed of a metal mesh and provided on a surface of the first insulating substrate;
a feeder line formed of a metal mesh and provided on the surface of the first insulator substrate, the feeder line extending between a first end and a second end connected to a feed portion of the antenna element;
the feed line extends from the first end in the second axial direction relative to a first axis and a second axis that are included in the surface and are perpendicular to each other;
The plurality of pixels included in the display device are arranged along the first axis direction and the second axis direction,
the metal mesh of the antenna element and the feed line includes a plurality of cells each having a first length in the first axis direction and a second length in the second axis direction;
an extending direction of the thin metal wires constituting the plurality of cells has an angle with respect to the first axis direction and the second axis direction;
the second length is longer than the first length,
An electronic device, wherein a first pitch of the plurality of pixels in the first axis direction is different from the first length, and a second pitch of the plurality of pixels in the second axis direction is different from the second length.