JP7657404B2 - Transparent antenna and display module - Google Patents

Description

The present invention relates to a transparent antenna and a display module including the transparent antenna.

In recent years, the fifth generation mobile communication system (5G) or sixth generation mobile communication system (6G) has been developed as a communication technology for mobile communication devices such as smartphones, tablets, mobile phones, and laptops.

Here, the millimeter waves used in the fifth generation mobile communication system (5G) have a strong directivity, a relatively short reach, and are easily blocked by metal, etc., so technology has been proposed for placing transparent antennas on displays (OLED, LCD, LED) and touch panels (including display-integrated metal thin-line panels) as 5G antennas (for example, Patent Document 1 and Patent Document 2).

Because such transparent antennas are placed on top of a display panel or touch panel, they are required to be thinner for ease of implementation.

Here, an antenna including a patch antenna is a patch antenna that includes a planar element made of a mesh and a ground layer, but a patch antenna requires a ground layer on the back side facing the antenna pattern.

Because patch antennas have a ground layer, they are known to operate more stably than antennas that do not have a ground layer, even if the display or touch panel placed underneath is made of a different material.

However, while Patent Document 1 and Patent Document 2 mention a planar patch antenna element made up of a mesh, they do not mention the specific configuration of the ground.

In a patch antenna, the antenna characteristics generally improve when the ground layer is separated from the antenna pattern layer, so in order to improve the antenna performance of the transparent antenna, the substrate in the patch antenna was made as thick as possible.

Japanese Patent Application Publication No. 2013-5013 US-A1-2019/0058264

However, if the distance between the antenna pattern and the ground layer on a single substrate is increased, the substrate will become thicker, resulting in a thick transparent antenna, which can cause problems when mounting on a display module.

In view of the above circumstances, the present invention aims to provide a transparent antenna capable of communication in the 5G band, which is less affected by the materials of nearby displays or touch panels, and which can improve antenna performance while reducing the overall thickness of the antenna.

In order to solve the above problems, in one aspect of the present invention,
A transparent antenna comprising a first transparent substrate, a second transparent substrate, a first thin metal wire layer on the first transparent substrate, and a second thin metal wire layer on the second transparent substrate,
the first thin metal wire layer and the second thin metal wire layer have an aperture ratio of 80% or more,
the first metal thin wire layer and the second metal thin wire layer have a surface resistance of 5 Ω/sq or less,
the first thin metal wire layer and the second thin metal wire layer are not in direct current conduction;
The first transparent substrate and the second transparent substrate are spaced apart by 100 μm or more;
the first thin metal wire layer has a patch-shaped antenna portion,
the second thin metal wire layer is formed over at least a region including the antenna portion when viewed from above;
A transparent antenna is provided.

According to one embodiment, a transparent antenna is less affected by the materials of a nearby display or touch panel, improving antenna performance while reducing the overall thickness of the antenna.

An overall view showing the position of a transparent antenna in an electronic device equipped with a display. FIG. 2 is a cross-sectional view of the electronic device of FIG. 1 taken along line AA. FIG. 2 is an exploded cross-sectional view showing details of the display module. 1 is a perspective view of a transparent antenna according to a first configuration example of the present invention; (A) A top view of a first transparent substrate, (B) a bottom view of the first transparent substrate, (C) a top view of a second transparent substrate, and (D) a bottom view of the second transparent substrate of a transparent antenna relating to a first configuration example. FIG. 2 is an explanatory diagram of a transparent conductor of the transparent antenna of the present invention. 1A is a cross-sectional view and FIG. 1B is a perspective view showing a pseudo display module in which a transparent antenna according to a first configuration example of the present invention is sandwiched between a transparent cover and a resistor simulating a display. 1A and 1B are a cross-sectional view and a perspective view, respectively, showing a pseudo display module including a transparent antenna according to Comparative Example 1. 1A and 1B are a cross-sectional view and a perspective view, respectively, showing a pseudo display module including a transparent antenna according to Comparative Example 2. A graph showing gain at each frequency in a pseudo display module including a transparent antenna according to the present invention in FIG. 7, a pseudo display module including a transparent antenna according to Comparative Example 1 in FIG. 8, and a pseudo display module including a transparent antenna according to Comparative Example 2 in FIG. 9. 11 is a schematic diagram of an experiment showing the presence or absence of a connection between the second transparent substrate of the transparent antenna and the ground substrate. 12 is a table showing the signal-to-noise ratio of the touch panel in FIG. 11 when connected and when not connected (floating); FIG. 11 is a perspective view of a transparent antenna according to a second configuration example of the present invention. (A) A top view of a first transparent substrate, (B) a bottom view of the first transparent substrate, (C) a top view of a second transparent substrate, and (D) a bottom view of the second transparent substrate of a transparent antenna relating to a second configuration example.

Below, we will explain the form for implementing the present invention with reference to the drawings. In the following drawings, the same components are given the same reference numerals, and duplicate explanations may be omitted. Below, we will explain an embodiment in which a transparent antenna of the present invention is applied.

The transparent antenna 100 of the present invention can be applied, for example, to a fifth generation mobile communication system (5G) or a sixth generation mobile communication system (6G).

<Electronic devices>
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 a transparent antenna 100 of the present invention, will be described. Fig. 1 is an overall view showing the position of the transparent antenna 100 in the electronic device 200 equipped with the display module D of the present invention. Fig. 2 is a cross-sectional view of the A-side of the electronic device 200 in Fig. 1.

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, the XYZ coordinate system is defined and explained. Also, for the sake of convenience, a planar view refers to an XY plane view, and the explanation is given using the up-down 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 up-down direction, but these do not represent the universal up-down and horizontal directions.

In addition, in directions such as parallel, right-angled, orthogonal, horizontal, vertical, up-down, left-right, etc., deviations are permitted to a degree that does not impair the effects of the disclosure in the embodiments. Furthermore, the X direction, Y direction, and Z direction respectively represent directions parallel to the X axis, directions parallel to the Y axis, and directions parallel to the Z axis. The X direction, Y direction, and Z direction are mutually perpendicular. The XY plane, YZ plane, and ZX plane respectively represent imaginary planes parallel to the X direction and Y direction, imaginary planes parallel to the Y direction and Z direction, and imaginary planes parallel to the Z direction and X direction.

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

1 and 2, a display module D capable of performing a display function is disposed on the entire top surface of the electronic device 200, or on at least a portion of the top surface. The transparent antenna 100 of the present invention is disposed above a touch panel 230 on a display panel 220. The upper side of the transparent antenna 100 of the present invention is visible from outside the electronic device 200 through a transparent cover 240, and is transparent so that the display panel 220 can be viewed from the outside through the transparent antenna 100.

Referring to FIG. 2, in the electronic device 200, the display panel 220, the touch panel 230, the transparent antenna 100, and the 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, 260D, and a battery 270.

1 and 2 show an example in which the electronic device 200 in which the transparent antenna 100 is mounted is a smartphone, but the electronic device in which the transparent antenna of the present invention is mounted may have another configuration as long as it includes a housing 210, a transparent cover 240, and a display panel 220. In addition, the electronic device 200 may not be provided with a touch panel 230.

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

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

The transparent cover 240 is attached to the opening end 211 of the housing 210, thereby 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 transparent antenna 100 and the 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 the display panel 220 provided inside can be seen through the transparent cover 240 from the outside of the electronic device 200.

Electronic components 260A to 260C are mounted on wiring board 250. A power supply line shown by a dotted line in FIG. 2, which extends from transmission area 120 of the transparent antenna (see FIG. 5), is connected to wiring board 250. Wiring board 250 and transmission area 120 of transparent antenna 100 may be connected using a connector, an ACF (Anisotropic Conductive Film), or the like, or may be connected using other components.

As an example, electronic component 260A is a communication module that is connected to transmission area 120 of transparent antenna 100 via wiring on wiring board 250 and processes signals transmitted or received via transparent antenna 100. Furthermore, central electronic component 260B is, for example, a camera.

Electronic components 260C, 260D are, for example, components that perform information processing related to the operation of electronic device 200, and are realized by a computer including, 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 for the operation of display module D and electronic components 260A to 260D, etc.

<Display module>
Next, the position of the transparent antenna 100 of the present invention in the display module D will be described.

Although not shown in Figure 2, as shown in Figure 3, the display module D has a polarizer 280 between the touch panel 230 and the transparent cover 240. Also, although shown as a single component in Figure 2, the transparent antenna 100 is composed of two substrates, a first transparent substrate 101 and a second transparent substrate 102, sandwiching the polarizer 280.

Between each substrate, in order to bond the substrates together, there are provided, from the outside in, a first adhesive layer 291 which is the outermost adhesive layer, a second adhesive layer 292 which is sandwiched between the antenna substrates, a third adhesive layer 293, and a fourth adhesive layer 294 which is the bottommost adhesive layer. The adhesive layers 291 to 294 are made of a transparent optical adhesive OCA (Optical Clear Adhesive).

3 shows an example in which the touch panel 230 is a "metallic thin wire layer for an on-cell touch panel" formed directly on the surface of the display panel 220 without providing an adhesive layer. However, an adhesive layer may be provided between the touch panel 230 and the display panel 220. In the configuration of FIG. 3, the touch panel 230 provided on the display panel 220 functions as a conductive layer (first conductive layer) for the transparent antenna 100 in the display module D.

2 and 3 show an example in which a touch panel 230 is provided in the display module D, but the touch panel 230 may not be mounted in the display module D mounted in the electronic device 200. In that case, the display panel 220 (e.g., the cathode of an OLED display panel) functions as a conductive layer for the transparent antenna 100 in the display module D. The surface resistance of the conductive layer is, for example, 5 Ω/sq to 20 Ω/sq.

The conductive layer (touch panel 230 or display panel 220) and the ground region which is the second metal thin line layer on the second transparent substrate 102 of the transparent antenna 100 are not in direct current conduction with each other, but can share power in alternating current in the sense of high frequencies such as the frequency used by the antenna. Even if power can be shared in alternating current, the conductive layer and the second metal thin line layer of the transparent antenna may include regions which do not overlap when viewed from above. For example, in the cross section of FIG. 2, the transparent antenna is partially provided with respect to the display panel 220, so an example is shown in which the transparent antenna 100 is partial with respect to the conductive layer, but the transparent antenna 100 may protrude outside the conductive layer, so that the conductive layer may be partial with respect to the transparent antenna 100.

The display panel 220 is, for example, a liquid crystal display panel, an organic EL (Electro-luminescence) or an OLED (Organic Light Emitting Diode) display panel, and in any configuration, is positioned at the bottom of the display module D.

1, in the display module D, the transparent antenna 100 is provided partially, so that the touch panel 230, the polarizing plate 280, and/or the adhesive layers 291-294 may be made thinner in the area where the transparent antenna 100 is provided than in other areas, or the polarizing plate 280 and/or the adhesive layers 291-294 may not be provided. This makes it possible to prevent only the transparent antenna 100 portion from protruding in the display module D.

It was also found that if the transparent antenna 100 is too thick, problems arise in that the edges of the transparent antenna 100 are visible and air is more likely to become mixed in at the boundaries with the adhesive layers 291-294. The thicknesses of the first transparent substrate 101 and the second transparent substrate 102 of the transparent antenna 100 are each preferably 300 μm or less, more preferably 150 μm or less, and particularly preferably 100 μm or less. From the viewpoint of ease of handling, the thicknesses of the respective transparent substrates 101, 102 of the transparent antenna 100 are preferably 10 μm or more, and more preferably 50 μm or more.

Furthermore, as long as the transparent antenna 100 has a predetermined overlapping portion in the vertical direction, which will be described later, 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 constituting the transparent antenna 100 may have the same or different substrate thicknesses, but if they are different, it is preferable that the thickness t1 of the first transparent substrate 101 is less than the thickness t2 of the second transparent substrate 102.

In addition, as described below, in the transparent antenna 100 of the present invention, the second adhesive layer 292, the polarizing plate 280, and the third adhesive layer 293 sandwiched between the transparent substrates 101 and 102 function as dielectrics so that the substrates 101 and 102 are not connected by wiring, but can be connected in an alternating current manner. It is preferable that the dielectric constants ε of the second adhesive layer 292, the polarizing plate 280, and the third adhesive layer 293, which act as dielectrics, are in a range between the dielectric constant ε1 of the first transparent substrate 101 and the dielectric constant ε2 of the second transparent substrate 102.

Although Figures 1 and 2 show an example in which both ends of the display module D in the ±Y direction are gently curved, the display module D may be flat with no curved ends. In that case, the transparent antenna 100 may also be flat. Note that if the transparent antenna 100 is partially curved, the transmission area described below will be curved.

<First Configuration Example of Transparent Antenna>
Next, the configuration of the transparent antenna 100 according to the first configuration example of the present invention will be described with reference to Figures 4 to 6. Figure 4 is a perspective view of the transparent antenna 100 according to the first configuration example of the present invention. Figure 5 is an explanatory diagram of the transparent antenna 100 according to the first configuration example, where (A) is a top view of the first transparent substrate 101 as seen from the +Z direction, and (B) is a bottom view of the first transparent substrate 101 as seen from the -Z direction. Also, Figure 5(C) is a top view of the second transparent substrate 102 as seen from the +Z direction, and (D) is a bottom view of the second transparent substrate 102 as seen from the -Z direction. Note that even when a part of the transparent antenna 100 is arranged along a curve as in Figure 1, Figure 4 shows the state before the transparent antenna 100 is folded parallel to the XY plane.

In this configuration example, the transparent antenna 100 has an antenna pattern 110 and a transmission area 120 provided on the upper surface (front surface) side of the first transparent substrate (also called the first transparent base material) 101. The antenna pattern 110 in this configuration is an example of a patch-type antenna. And, a ground area 130, which is a ground layer, is provided on the lower surface (rear surface) side of the second transparent substrate 102 (also called the second transparent base material).

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, so that in the transparent antenna 100, the inter-substrate distance ds between the first transparent substrate 101 and the second transparent substrate 102 shown in Figure 4 is approximately 150 μm apart.

4, the antenna pattern 110 is provided on the upper surface side of the first transparent substrate 101, and the ground region 130 is provided on the lower surface side of the second transparent substrate 102, so that the distance dm between the antenna pattern 110, which is a metal thin line layer, and the ground region 130 is about 500 μm apart. The distance dm between the metal thin line layers 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 immediately above the touch panel 230 or the 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 direction of polarization and the thickness (d) of the substrate, is low. On the other hand, since the first transparent substrate 101 is separated from the touch panel 230 or the display panel 220, the retardation δ1 does not need to be low. Therefore, it is preferable that the retardations in 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, the first transparent substrate 101 is made of PET (polyethylene terephthalate resin) or COP (cycloolefin polymer), and the second transparent substrate 102 is, 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 the clarity of the image. Therefore, retardation is evaluated using light in the visible light range (wavelengths 380 nm to 780 nm).

On the other hand, the dielectric constant is a quantity related to the antenna characteristics. Therefore, the dielectric constant is evaluated in the wavelength range of the radio waves 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 metal fine wires of the second metal fine wire layer becomes electrically narrow, suppressing leakage of radio waves from the second metal fine wire layer to the lower side. For example, the dielectric constant of the PET constituting the first transparent substrate 101 is 3.31 at 35 GHz, and the dielectric constant of the COP constituting the second transparent substrate 102 is 2.31 at 35 GHz.

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

In the transparent antenna 100 of this configuration, the antenna pattern 110 is provided on the upper first transparent substrate 101 near the center in the longitudinal direction of the first transparent substrate 101. The antenna pattern 110 of this configuration is an example of a patch-type antenna.

The antenna pattern 110, which is the antenna portion, has a first linear element 111 and a surface patch element 112.

In detail, one end of the first line element 111 is a feed point F that connects to the signal line 121 of the transmission area 120, and extends in a first direction (+Y direction) that is the transmission direction from the feed point F. The other end of the first line element 111 is connected to the planar patch element 112.

The planar patch element (also called patch portion or patch element) 112 is a patch-type antenna having a substantially rectangular shape with a predetermined area. In the planar patch element 112, grooves 113 and 114 are formed near the boundary with the first line element 111 in the -Y direction. In this configuration, all elements of the antenna pattern 110 are provided on the +Z side, which is the upper surface side of the first transparent substrate 101. The grooves 113 and 114 of the patch element 112 are provided to match the radiation resistance, which is determined from the thickness and dielectric constant of the surrounding materials of the patch element 112 and the patch element size, with the feed line impedance.

Here, assuming that the length of the planar patch element 112 in the first direction is Y112 and the length in the second direction is X112, the wavelength on the first transparent substrate 101 at the resonant frequency f1 (28 GHz) of the transparent antenna 100 is _λ01 , and Y112 is set to an integer multiple of approximately _0.5λ01 , and X112 is set to a value smaller than _1.0λ01 . Therefore, when it is desired to improve the antenna gain in the frequency band f1, it is advisable to adjust X112 and Y112, which define the size of the planar patch element 112, to within ±10% of approximately 2.5 mm, for example.

The transmission area (also called the power supply area) 120, which is the transmission section, is disposed at the longitudinal end (-Y direction end) of the first transparent substrate 101. In this configuration example, the transmission area 120 is a coplanar waveguide, and has a signal line (also called a signal line or transmission line) 121 that extends from the center of the short side direction (±X direction) of the substrate 101 on the surface on the +Z side, and planar ground sections 122, 123 that are grounded in a state in which the signal line 121 is sandwiched in the short side direction. The tip of the signal line 121 that transmits the signal (power) in the transmission direction is electrically connected to the first line element 111 of the antenna pattern 110, and the connection point is the power supply point F.

In this configuration example, the signal line 121 and the ground sections 122, 123 constituting the transmission area 120 are all provided only on the upper surface side (+Z side) of the first transparent substrate 101. Therefore, in the first transparent substrate 101 of this configuration, the components of the antenna pattern 110 and the transmission area 120, which function as the first metal thin line layer, are all provided on the same plane on the upper surface side (+Z side) of the first transparent substrate 101.

When the transparent antenna 100 is incorporated into the electronic device 200, the signal line 121 of the transmission area 120 is electrically connected to the wiring board 250 and the electronic component 260A, which is a communication circuit, and power P is supplied. In FIG. 4, as an example, the transmission area 120 is shown configured to be approximately 1/2 from the end on the -Y direction side. Note that the range of the transmission area 120 may be approximately 1/4 to 3/4 on the -Y direction side.

4 illustrates an example in which the end of the transmission region 120 extends to the end (-Y side end) of the first transparent substrate 101, but a part or all of the transmission region 120 may be located outside the periphery of the first transparent substrate 101. In addition, the transmission region 120 may be formed to be flexible so that it can 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, in the second transparent substrate 102 below the transparent antenna 100, the ground region 130 which is the second metal thin wire layer is provided from near the center of the longitudinal direction of the second transparent substrate 102 to the +Y side.

However, the ground area 130 provided on the second transparent substrate 102 is not limited to the configuration shown in Figures 4 and 5, and the ground area 130 may be configured to overlap the entire area of the planar patch element 112 and at least a part of the ground parts 122 and 123 of the transmission region 120 in the longitudinal direction (±Y direction) of the substrate 102 in a top view. Also, the ground area 130 provided on the second transparent substrate 102 may be configured to overlap the entire area of the planar patch element 112 and at least a part of the ground parts 122 and 123 of the transmission region 120 in the short direction (±X direction) in a top view. Alternatively, the ground area 130 may be provided on the entire surface of the -Z side of the second transparent substrate 102.

Here, the ground area 130 provided on the second transparent substrate 102 is not connected to the first transparent substrate 101 by wiring, but it is desirable that the ground area 130 and the ground parts 122, 123 of the transmission area 120 of the first transparent substrate 101 share an AC current. Therefore, it is preferable that the ground area 130 and the ground parts 122, 123 of the transmission area 120 overlap in the Y direction to form an overlapping part Ov. In particular, it is sufficient that the overlapping part Ov is 0.25λ ₀₁ or more in the Y direction, and more preferably, if it is an odd multiple of 0.25λ ₀₁ , the overlapping part acts as a choke.

In addition, it is preferable that the ground area 130 covers at least the entire area of the first linear element 111 and the planar patch element 112 that form the patch antenna on the +Y side, and is further 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 planar patch element 112.

That is, it is preferable that the ground area 130 has X130 of 7.5 mm or more and Y130 of 7.5 mm or more, as shown by the dotted line in Figure 5 (D).

4 and 5 show an example of a configuration in which the first 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 in the transparent antenna 100 of the present invention, the first substrate 101 and the second transparent substrate 102 may have different vertical and horizontal sizes, and may be configured to only partially overlap in the vertical direction. If the two substrates 101 and 102 are misaligned in size or position, it is sufficient that the ground area 130 of the second substrate 102 overlaps with the entire area of the antenna pattern 110, which is a patch antenna, at least in the XY direction, and covers the back side so that the ground area 130 overlaps with the ground parts 122 and 123 of the transmission area 120 by 0.25 wavelengths or more in the Y direction.

Here, the antenna pattern 110, transmission area 120, and ground area 130 shown in mesh form in Figures 4 and 5 are made of transparent conductors as shown in Figure 6 below.

<Transparent conductor (thin metal wire layer) of transparent antenna>
Fig. 6 is an explanatory diagram of the transparent conductor 30 of the transparent antenna 100 of the present invention. 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 constitute, for example, the antenna pattern 110, the transmission region 120, and the ground region 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 it.

More specifically, the transparent conductor 30 is a layer of conductive lines, i.e., a metal thin wire layer, which is formed, for example, in a mesh shape to increase light transparency. As shown in Fig. 6, in the mesh-shaped metal thin wire layer, a plurality of metal thin wires 31 extending in one direction and a plurality of metal thin wires 32 extending in the other direction are arranged to intersect with each other, and openings (through holes) 33 are formed as mesh-like gaps (openings).

When the transparent conductor 30 is formed in a mesh shape, the mesh openings 33 may be rectangular or rhombic. When the mesh openings 33 are formed in a rectangular shape, the mesh preferably has square openings, which provides good design. The mesh openings 33 may also have a random shape formed by a self-organizing method, which can suppress moire. The line widths w31 and w32 of the metal fine wires 31 and 32 constituting the mesh are preferably 1 to 10 μm, and more preferably 1 to 5 μm. The line spacings (also called openings or pitches) p31 and p32 between the multiple metal fine wires 31 and between the multiple metal fine wires 32 of the mesh are preferably 50 to 500 μm, and more preferably 100 to 400 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 larger 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, the visible light transmittance can be increased 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 addition, in the transparent conductor 30, the conductor thickness t is set smaller than the line width (conductor width) w31, w32 of the mesh-like thin lines. This is because if the aspect ratio exceeds 1, the structure becomes unbalanced, becomes fragile, and is difficult to manufacture. However, since the sheet resistance value can be reduced as the conductor thickness t is thicker, the efficiency of the antenna is better if the conductor thickness t is thicker, so it is preferable that t is smaller than w 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 metallic materials such as silver, aluminum, chromium, nickel, gold, platinum, tin, iron, etc. can also be used, and the conductive material is not limited to these materials.

The antenna pattern 110, transmission area 120, and ground area 130 realized by such a transparent conductor 30 are transparent, have high light transmittance so that they are difficult to see with human eyesight, and can function as conductors. In addition, the transparent conductor 30 constituting these metal thin line layers has 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.

Here, as shown in FIG. 3, the first transparent substrate 101 above the transparent antenna 100 is provided on the surface side of the polarizing plate 280. Therefore, it is preferable to subject the metal thin line layer constituting the antenna pattern 110 and the transmission area 120 formed on the first transparent substrate 101 to a blackening treatment that makes it less likely to reflect visible light. In the blackening treatment, the surface of the metal thin line is coated with a material containing copper oxide (CuO) or copper nitride (CuN). Note that the metal thin line of the ground area 130, which is the metal thin line layer of the second transparent substrate 102 provided on the inner side of the polarizing plate 280, does not need to be processed.

Generally, patch antennas are said to be stable even when conductors with various surface resistance values are placed close to the antenna because the back side of the patch antenna is shielded by a ground conductor. On the other hand, it is generally said that the antenna characteristics are improved when the ground layer is separated from the antenna pattern layer.

Therefore, we compared the antenna performance of transparent antennas, including patch-type antennas, with and without a ground layer and when the distance between the antenna pattern and the ground layer was changed.

<Experimental Example 1 (Simulation Example)>
Therefore, the inventors of the present application performed various simulations on a pseudo display module in which a transparent cover 240 and a metal conductor M having resistance are provided above and below the transparent antenna 100 of the present invention as shown in FIG.

Figure 7 is an explanatory diagram showing a pseudo display module SD in which a transparent antenna of the first configuration example of the present invention is sandwiched between a transparent cover and a resistor that mimics a display. In Figure 7, (A) is a schematic cross-sectional view of the pseudo display module SD, and (B) is a perspective view of the pseudo display module SD.

In more detail, a metal conductor M with a sheet resistivity of 1 Ω/sq (ohms per square, sometimes written as Ω/□) was arranged on the bottommost side of the pseudo display module SD, which acts as a resistor simulating a display or touch panel. A fourth adhesive layer 294 was arranged on top of the metal conductor M.

Then, as shown in FIG. 7(A), a second transparent substrate 102, which is the lower substrate of the transparent antenna 100, is provided between the fourth adhesive layer 294 and the third adhesive layer 293. A third adhesive layer 293, a polarizing plate 280, and a second adhesive layer 292 are arranged on top of that, and a first transparent substrate 101, which is the upper substrate of the transparent antenna 100, is provided on top of that. Then, a first adhesive layer 291 and a transparent cover 240 are arranged on top of the first transparent substrate 101.

In order to comparatively verify the antenna characteristics of the present invention, the inventors created a pseudo display module SDx relating to comparison example 1 shown in Figure 8 and a pseudo display module SDy relating to comparison example 2 shown in Figure 9, and performed a gain simulation.

Figure 8 shows (A) a cross-sectional view and (B) an oblique view of a pseudo display module SDx including a transparent antenna relating to comparison example 1.

The pseudo display module SDx in Fig. 8 differs from the configuration in Fig. 7 in that the second transparent substrate 102 and the fourth adhesive layer 294 are not provided. Therefore, in this pseudo display module SDx, a ground area that shields the lower side of the antenna pattern 110 is not provided.

Figure 9 shows (A) a cross-sectional view and (B) an oblique view of a pseudo display module SDy including a transparent antenna relating to comparison example 2.

The pseudo display module SDy in Fig. 9 differs from the configuration in Fig. 7 in that it does not have a second transparent substrate 102 and a fourth adhesive layer 294, it has a ground area 190 on the back surface of the first transparent substrate 101Y, and in the upper transmission area, it does not have ground sections 122 and 123 on the upper surface side, but only has a signal line 121Y. It also differs in that the position of the polarizing plate 280Y is above the transparent antenna substrate 101Y.

Below, we explain the gains simulated using the pseudo display module SD in Figure 7, the pseudo display module SDx relating to comparison example 1 in Figure 8, and the pseudo display module SDy relating to comparison example 2 in Figure 9.

When simulating this gain, the dimensions of each part of the transparent antenna 100 of the pseudo display module SD in FIG.
X240: 15mm
Y240: 15 mm
X101: 7.5mm
Y101: 10 mm
X102: 15mm
Y102: 12 mm
L111: 0.5mm
X112: 2.5mm
Y112: 2.5mm
W121: 0.4mm
X120: 5.6mm
Y120: 5 mm
X130: 15mm
Y130: 12 mm
As a result, the length in the Y direction of the overlap between the ground sections 122 and 123 of the substrate 101 and the ground area 130 of the substrate 102 is 2 mm.

The dimensions of the transparent conductor 30, which is a thin metal wire layer constituting the antenna pattern 110, the transmission area 120, and the ground area 130, are expressed in μm as follows:
Conductor thickness of transparent conductor 30: 2 μm
Conductor width w31, w32: 3 μm
Line spacing p31, p32: 100μm (200μm)
And,
The sheet resistance of the transparent conductor is about 0.5 Ω/sq.

The thickness of each layer in the pseudo display module SD of the present invention shown in FIG. 7 is expressed in μm as follows:
Thickness of transparent cover 240: 500
Thickness of the first adhesive layer 291: 150
Thickness of transparent conductor 30 (110, 120): 2
Thickness of the first transparent substrate 101: 100
Thickness of second adhesive layer 292: 150
Thickness of polarizing plate 280: 150
Thickness of the third adhesive layer 293: 150
Thickness of second transparent substrate 102: 125
Thickness of transparent conductor 30 (130): 2
Thickness of fourth adhesive layer 294: 150
It is.
In particular, the transparent substrates 101 and 102 have thicknesses of 100 μm and 125 μm, respectively.

As a result, in this example, the distance dm between the antenna pattern 110 on the upper side of the transparent substrate 101 and the ground area 130 on the lower side of the transparent substrate 102 is 675 μm, and the inter-substrate distance ds between the substrate 101 on which the antenna portion is provided and the substrate 102 on which the background is provided is 450 μm.
Since the surface impedance for which the surface resistance is set is set as the boundary condition, the metal conductor M is set to have no thickness.

The dielectric constants of the dielectric layers and the respective portions of the dielectric material in the pseudo display module SD of the present invention shown in FIG.
Transparent cover 240:6.7
First adhesive layer 291: 2.6
First transparent substrate 101: 3.2
Second adhesive layer 292: 2.6
Polarizing plate 280:2.9
Third adhesive layer 293: 2.6
Second transparent substrate 102: 2.4
Fourth adhesive layer 294: 2.6

The thickness of each layer in the pseudo display module SDx of Comparative Example 1 shown in Figure 8 is the same as that of each layer in SD, and does not include the thickness of the second transparent substrate 102, the transparent conductor 30 (130) provided on the second transparent substrate 102, or the thickness of the fourth adhesive layer 294. In this configuration, the metal conductor M functions as a pseudo background conductor of the patch antenna, and the surface resistance of the metal conductor M is 1.0 Ω/sq. In this configuration, the distance from the antenna pattern 110 to the metal conductor M is 550 μm. The inter-substrate distance between the substrate 101 on which the antenna portion is provided and the metal conductor M is 450 μm.

The thickness of each layer in the pseudo display module SDy of Comparative Example 2 shown in Figure 9 is the same as that of each layer in SD, except that there is no thickness of the second transparent substrate 102, the transparent conductor 30 (130) provided on the second transparent substrate 102, or the fourth adhesive layer 294, and a ground region 190 is provided on the back surface of the first transparent substrate 101Y. In this configuration, the ground region 190 functions as a background conductor for the patch antenna, and the surface resistance of the ground region 190 is set to 0.5 Ω/sq. In this configuration example, the distance from the antenna pattern 110 to the ground region 190 is the substrate thickness of the first transparent substrate 101Y, for example 100 μm.

Figure 10 shows the gain at each frequency when electromagnetic field analysis is performed on the pseudo display module SD including the transparent antenna of the present invention in Figure 7, the pseudo display module SDx including the transparent antenna of comparison example 1 in Figure 8, and the pseudo display module SDy including the transparent antenna of comparison example 2 in Figure 9.

Comparing the maximum gains in the graph of Figure 10, the pseudo display module SDx of comparison example 1 had a maximum gain of +2.7 dB, the pseudo display module SDy of comparison example 2 had a maximum gain of +0.2 dB, and the pseudo display module SD of the present invention had a maximum gain of +3.0 dB.

In addition, when comparing the gains at frequencies around the 5G band of 25 to 30 GHz, the gains are greatest in the order SD of the present invention > SDx of Comparative Example 1 > SDy of Comparative Example 2.

Here, the gain (radiation efficiency) of the patch antenna is determined by the following two points.
(1) The greater the distance between the antenna element and the ground conductor, the better. (2) The lower the resistance of the background conductor, the better.

In Comparative Example 2, the ground region 190 serving as the background conductor is close within the same substrate, and as shown by the dashed line in the graph of Figure 10, the gain is lower than that of the display module SD of the present invention shown by the solid line due to reason (1). This shows that the gain and maximum gain in the 5G band can be improved by providing the background conductor on a separate substrate and increasing the distance between the antenna pattern 110 and the ground region 130, rather than providing the background conductor on the same substrate as the antenna section.

On the other hand, in Comparative Example 1, the background conductor is a metal conductor M, which has a higher resistance than the ground region 130 composed of a thin metal wire layer. Therefore, even if the distance between the substrates is approximately the same, the gain is lower than that of the display module SD of the present invention shown by the solid line, as shown by the dotted line in Figure 10, due to reason (2). In this experiment, an example is shown in which the resistance of the metal conductor M is 1.0 Ω/sq, but actual touch panels and display panels may have even higher resistance. Therefore, it is preferable in terms of the gain of the patch antenna to provide a ground region that has a low surface resistance and serves as a background conductor separately from the metal conductor M, as in the present invention.

Thus, by comparing Comparative Example 1 and Comparative Example 2 shown in the graph of Figure 10, it can be said that the antenna characteristics of the patch antenna are improved in the configuration of the present invention by providing a ground layer separate from the metal conductor and by this layer being a dedicated substrate separated from the substrate on which the antenna pattern is formed.

<Experimental Example 2>
Fig. 11 is a schematic diagram of an experiment showing the presence or absence of connection between the second transparent substrate 102 of the transparent antenna and the ground of the housing. Fig. 12 is a table showing the S/N ratio of the touch panel when the second transparent substrate of Fig. 11 is connected to the housing and when it is not connected (floating).

In FIG. 12, the first row shows the state where a second transparent substrate without a mesh is placed on the touch panel, and the second to fifth rows show the state where a second transparent substrate with a mesh constituting a metal thin line layer is placed on the touch panel. The left column of the table in FIG. 12 shows the type of mesh constituting the metal thin line layer, which is a transparent conductor, shown in FIG. 6. Two types of mesh were used: mesh line width w = 4 μm, mesh line spacing (pitch) p = 120 μm, and mesh line width w = 4 μm, mesh pitch p = 60 μm. The center column shows the presence or absence of connection between the second transparent substrate shown in FIG. 11 and the ground part of the housing. The right column shows the signal-to-noise ratio of the touch panel under the transparent antenna when a finger is moved on the top surface as shown in FIG. 11. The case of none in the left column refers to the case where a transparent antenna is not provided on the touch panel.

Comparing the second and fourth rows with the third and fifth rows in Figure 12, it can be seen that, regardless of which mesh is used as the transparent conductor, the floating state results in a smaller drop in the S/N ratio compared to the structure without a transparent antenna shown in row 1. Also, comparing the second and third rows with the fourth and fifth rows, it can be seen that the larger the line spacing p and the larger the opening, the smaller the drop in the S/N ratio tends to be.

<Second Configuration Example of Transparent Antenna>
Next, a transparent antenna 100A according to a second configuration example of the present invention will be described with reference to FIGS.

Figure 13 is a perspective view of a transparent antenna 100A according to a second configuration example of the present invention. Figure 14 is an explanatory diagram of the transparent antenna 100A according to the second configuration example, where (A) is a top view of the first transparent substrate 101A and (B) is a bottom view of the first transparent substrate 101A. Also, Figure 14 (C) is a top view of the second transparent substrate 102 and (D) is a bottom view of the second transparent substrate 102. Note that even when the transparent antenna is arranged along a curve as in Figure 1, Figures 13 and 14 show the state before the transparent antenna is folded parallel to the XY plane.

In the transparent antenna 100A of this configuration example, the transmission area 140 in the first transparent substrate 101A is configured as a microstrip line, which is different from the first configuration example, but all other points are the same.

In this configuration example, the transmission area (also called the power supply area) 140, which is the transmission section, is a microstrip line, and has a signal line 141 extending from the center of the short side (±X direction) of the substrate on the surface on the +Z side (front side), and a planar ground section 142 that is grounded to a predetermined range on the +Y side from the end on the -Y side over the entire short side on the surface on the +Z side (rear side). With this configuration, the transmission area 140 is disposed at the end of the longitudinal direction (end on the -Y side) of the first transparent substrate 101A. The tip of the signal line 141 in the transmission direction that transmits the signal (power P) is electrically connected to the first line element 111 of the antenna pattern 110, and the connection point is the power supply point FDa.

In this configuration example, the signal line 141 constituting the transmission area 140 is provided on the upper surface side (+Z side) of the first transparent substrate 101A, and the ground section 142 is provided on the lower surface side (-Z side) of the first transparent substrate 101A. The ground section 142 of the microstrip line is located below the portion of the first transparent substrate 101a where the antenna pattern 110 is not provided, as it is a grounding area for the transmission area.

In addition, in the second transparent substrate 102 below the transparent antenna 100A, as in the first configuration example, the ground region 130 which is the second metal thin wire layer is provided from near the center of the longitudinal direction of the second transparent substrate 102 to the +Y side.

However, the ground area 130 provided on the second transparent substrate 102 is not limited to the configurations shown in Figures 13 and 14, and the ground area 130 may be configured to overlap the entire area of the planar patch element 112 and at least a part of the ground portion 142 of the transmission area 140 in the longitudinal direction (±Y direction) in a top view. Also, the ground area 130 provided on the second transparent substrate 102 may be configured to overlap the entire area of the planar patch element 112 and at least a part of the ground portion 142 of the transmission area 140 in the short direction (±X direction) in a top view. Alternatively, the ground area 130 may be provided on the entire surface of the -Z side of the second transparent substrate 102.

Here, the ground area 130 provided on the second transparent substrate 102 is not connected to the first transparent substrate 101A by wiring, but it is desirable that the ground area 130 and the ground portion 142 of the transmission area 140 of the first transparent substrate 101A share the ground area 130 in an AC manner. Therefore, the overlap Ov between the ground area 130 and the ground portion 142 of the transmission area 140 in the Y direction may be 0.25 wavelengths (λ ₀₁ ) or more, and more preferably an odd multiple of 0.25 wavelengths, since the overlapping portion acts as a choke. The upper limit of the overlap is preferably 2.5 wavelengths or less, more preferably 1 wavelength or less, and even more preferably 0.8 wavelengths or less, from the viewpoint of saving space.

In the present invention, in both the first and second configuration examples, the transparent antenna is constructed by separating two substrates, one for the antenna pattern and one for the ground. Therefore, even if a distance is required between the antenna pattern and the ground area on the back of the antenna to ensure a certain gain, a transparent antenna can be realized without making the transparent antenna itself significantly thicker.

For example, even if there are significant constraints on the allowable thickness of a transparent antenna in an electronic device, such as 100 μm or less, the transparent antenna can be made thinner and within the thickness constraints by reducing the thickness of each substrate while maintaining a specified distance between the antenna pattern and the ground area on the back of the antenna.

The above describes a transparent antenna as an exemplary embodiment of the present invention, but the present invention is not limited to the specifically disclosed embodiment, and various modifications and variations are possible without departing from the scope of the claims.

This international application claims priority to Japanese Patent Application No. 2020-143919, filed on August 27, 2020, and the entire contents of No. 2020-143919 are incorporated by reference into this international application.

30 Transparent conductor (metallic thin wire layer)
31 Thin metal wire 32 Thin metal wire 33 Opening 100, 100A Transparent antenna 101, 101A First transparent substrate (first transparent base material)
102 Second transparent substrate (second transparent base material)
110 Antenna pattern (antenna portion, patch antenna, transparent conductor, first thin metal wire layer)
111: First line element 112: Planar patch element 120: Transmission region (transmission section, feeding region, coplanar transmission line, first metal thin line layer)
121 Signal line 122 Ground section 130 Ground area (transparent conductor, second thin metal wire layer)
140 Transmission area (transmission section, power supply area, microstrip line, first metal thin line layer)
141 Signal line 142 Ground section 200 Electronic device 210 Housing 220 Display panel 230 Touch panel 240 Transparent cover (cover glass)
250 Wiring board 260A, 260B, 260C, 260D Electronic components 270 Battery 280 Polarizing plate (dielectric)
291 First adhesive layer 292 Second adhesive layer (dielectric)
293 Third adhesive layer (dielectric)
294 Fourth adhesive layer D Display module P Power FD Feed point SD Pseudo display module M Metal conductor ds Distance between the first transparent substrate and the second transparent substrate dm Distance between the metal thin line layers of the antenna pattern and the ground region Ov Overlap

Claims (13)

A transparent antenna comprising a first transparent substrate, a second transparent substrate, a first thin metal wire layer on the first transparent substrate, and a second thin metal wire layer on the second transparent substrate,
the first thin metal wire layer and the second thin metal wire layer have an aperture ratio of 80% or more,
the first metal thin wire layer and the second metal thin wire layer have a surface resistance of 5 Ω/sq or less,
the first thin metal wire layer and the second thin metal wire layer are not in direct current conduction;
The first transparent substrate and the second transparent substrate are spaced apart by 100 μm or more;
the first thin metal wire layer has a patch-shaped antenna portion,
the second thin metal wire layer is formed over an area including at least the antenna portion when viewed from above ,
the first metal wire layer has a transmission portion, the transmission portion being a coplanar waveguide;
the signal line and the ground portion of the coplanar waveguide are provided on an upper side of the first transparent substrate,
a ground portion of a transmission portion of the first thin metal wire layer and the second thin metal wire layer include an overlap when viewed from above;
The width of the overlap is 0.25 wavelengths or more and 2.5 wavelengths or less.
Transparent antenna. A transparent antenna comprising a first transparent substrate, a second transparent substrate, a first thin metal wire layer on the first transparent substrate, and a second thin metal wire layer on the second transparent substrate,
the first thin metal wire layer and the second thin metal wire layer have an aperture ratio of 80% or more,
the first metal thin wire layer and the second metal thin wire layer have a surface resistance of 5 Ω/sq or less,
the first thin metal wire layer and the second thin metal wire layer are not in direct current conduction;
The first transparent substrate and the second transparent substrate are spaced apart by 100 μm or more;
the first thin metal wire layer has a patch-shaped antenna portion,
the second thin metal wire layer is formed over an area including at least the antenna portion when viewed from above ,
the first metal thin wire layer has a transmission portion,
The transmission section is a microstrip line,
a signal line of the microstrip line is located on an upper side of the first transparent base material, and a ground portion of the microstrip line is located on a lower side of a portion of the first transparent base material where the antenna portion is not provided,
a ground portion of a transmission portion of the first thin metal wire layer and the second thin metal wire layer include an overlap when viewed from above;
The width of the overlap is 0.25 wavelengths or more and 2.5 wavelengths or less.
Transparent antenna. The first metal thin line layer is on the upper side of the first transparent substrate, and the second metal thin line layer is on the lower side of the second transparent substrate.
The transparent antenna according to claim 1 or 2 . The retardation δ1 of the first transparent substrate at a thickness of 100 μm is 1 or more and 10,000 or less, and the retardation δ2 of the second transparent substrate at a thickness of 100 μm is 0.1 or more and 1,000 or less, and δ1≧δ2;
The transparent antenna according to any one of claims 1 to 3 . The dielectric constant ε1 of the first transparent substrate and the dielectric constant ε2 of the second transparent substrate have a relationship of ε1 ≧ ε2.
The transparent antenna according to claim 4 . The first transparent substrate is PET or COP, and the second transparent substrate is COP;
The transparent antenna according to claim 4 or 5 . A transparent antenna,
A dielectric material;
A display module comprising: a display panel,
The transparent antenna is
The optical fiber display device includes a first transparent substrate provided with a first thin metal wire layer and a second transparent substrate provided with a second thin metal wire layer,
the first thin metal wire layer and the second thin metal wire layer have an aperture ratio of 80% or more,
the first metal thin wire layer and the second metal thin wire layer have a surface resistance of 5 Ω/sq or less,
the first thin metal wire layer and the second thin metal wire layer are not in direct current conduction;
The first transparent substrate and the second transparent substrate are spaced apart by 100 μm or more;
the first thin metal wire layer has a patch-shaped antenna portion,
the second thin metal wire layer is formed over an area including at least the antenna portion when viewed from above,
The dielectric is provided between the first transparent substrate and the second transparent substrate.
Display module. The dielectric constant ε1 of the first transparent substrate and the dielectric constant ε2 of the second transparent substrate satisfy a relationship of ε1≧ε2.
8. The display module of claim 7 . The dielectric material is a polarizer.
9. A display module according to claim 7 or 8 . a first conductive layer on the underside of the second transparent substrate of the transparent antenna;
The surface resistance of the first conductive layer is 5 Ω/sq to 20 Ω/sq.
A display module according to any one of claims 7 to 9 . The first conductive layer comprises:
The display panel has a function as a cathode of a touch panel provided on the display panel or an OLED display panel constituting the display panel.
The display module of claim 10 . the first conductive layer and the second thin metal wire layer of the transparent antenna are not in direct current conduction with each other;
12. A display module according to claim 10 or 11 . the first conductive layer and the second thin metal wire layer of the transparent antenna include an area where they do not overlap in a top view;
A display module according to any one of claims 10 to 12 .

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