Transparent electroconductive film

Abstract

A transparent electroconductive film (2) having an effective region (2a) and an ineffective region (2b), said transparent electroconductive film (2) comprising: a first base (41); an antenna (10) positioned in the effective region (2a) and provided on the first base (41); a first signal line (21) positioned in the ineffective region (2b), provided on the first base (41), and electrically connected to the antenna (10); and a first ground layer (43) provided on the first base (41). A second base (42) is disposed so as to face the first base (41). A second ground layer (44) is provided on the second base (42). The first ground layer (43) does not face the antenna (10), and the second ground layer (44) does face the antenna (10).

Description

Transparent Conductive Film

[0001] The present disclosure relates to a transparent conductive film.

[0002] Transparent conductive films having fine conductive lines formed on a transparent substrate are known. One such type of transparent conductive film is a film antenna having an antenna formed from fine conductive lines (see, for example, Patent Document 1). Film antennas are used in mobile devices requiring an antenna, such as smartphones or tablet devices. The antenna in a film antenna is formed from fine conductive lines having a line width of 100 μm or less, which is difficult to detect with the naked eye. This allows the antenna to be made transparent, so that the antenna can be easily mounted on a mobile device even if the mobile device is made thinner and lighter, reducing the space available for component placement.

[0003] International Publication No. 2021 / 229994

[0004] In some transparent conductive films having an antenna, the antenna is composed of multiple antenna elements. In this case, the transparent conductive film has multiple antenna elements and multiple signal lines connected to the multiple antenna elements formed on one surface of a transparent substrate, and a ground layer formed on the other surface of the transparent substrate.

[0005] In this case, one possible solution to suppress crosstalk between multiple signal lines is to thin the substrate to reduce the distance between the signal lines and the ground layer. However, reducing the distance between the signal lines and the ground layer also reduces the distance between the antenna, which is formed on the same layer as the signal lines, and the ground layer. This results in a decrease in antenna efficiency (gain).

[0006] As described above, conventional transparent conductive films have a problem in that it is difficult to simultaneously suppress crosstalk and maintain or improve antenna efficiency.

[0007] One aspect of the transparent conductive film according to the present disclosure is a transparent conductive film having a first region and a second region different from the first region, comprising: a first substrate; an antenna located in the first region and provided on the first substrate; a signal line located in the second region, provided on the first substrate, and electrically connected to the antenna; and a first ground layer provided on the first substrate, wherein a second substrate is disposed opposite the first substrate, and a second ground layer is provided on the second substrate, the first ground layer does not face the antenna, and the second ground layer faces the antenna.

[0008] According to the present disclosure, it is possible to suppress crosstalk while maintaining or improving antenna efficiency.

[0009] Fig. 1 is a diagram showing the configuration of an antenna module using a transparent conductive film according to an embodiment; Fig. 2 is a diagram showing the configuration of an antenna module using a transparent conductive film of a comparative example; Fig. 3 is a diagram showing the configuration of a mobile terminal using a transparent conductive film according to a modified example; Fig. 4 is a diagram showing the configuration of a mobile terminal using a transparent conductive film according to another modified example; Fig. 5 is a diagram showing the configuration of a mobile terminal using a transparent conductive film according to another modified example.

[0010] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. Note that each of the embodiments described below represents a specific example of the present disclosure. Therefore, the numerical values, shapes, materials, components, the arrangement and connection of the components, processes (steps), and the order of the processes shown in the following embodiments are merely examples and are not intended to limit the present disclosure. Therefore, among the components in the following embodiments, components that are not described in the independent claims that represent the superordinate concept of the present disclosure will be described as optional components.

[0011] Note that each figure is a schematic diagram and is not necessarily an exact illustration. Therefore, the scales and the like do not necessarily match in each figure. Furthermore, in each figure, substantially the same configuration is assigned the same reference numeral, and duplicate explanations are omitted or simplified. Furthermore, in this specification, the terms "up" and "down" do not necessarily refer to the upward direction (vertically upward) and downward direction (vertically downward) in absolute spatial recognition.

[0012] (Embodiment) An antenna module 1 according to an embodiment will be described using Figure 1. Figure 1 is a diagram showing the configuration of the antenna module 1 according to the embodiment. In Figure 1, (a) is a plan view of the antenna module 1, (b) is a cross-sectional view taken along line bb in (a), and (c) is a cross-sectional view taken along line cc in (a).

[0013] The antenna module 1 is an example of an antenna device having an antenna for emitting radio waves into space and receiving radio waves from space. The antenna module 1 can be used, for example, in devices for 3G to 5G communications. The communication frequency of the antenna module 1 is, for example, a predetermined frequency band of 0.5 GHz to 30 GHz. For example, the communication frequency of the antenna module 1 is the 3.7 GHz band, the 4.5 GHz band, or the 28 GHz band.

[0014] As shown in FIG. 1( a ), the antenna module 1 includes a transparent conductive film 2 and a flexible wiring board 3 connected to the transparent conductive film 2 .

[0015] The transparent conductive film 2 is an example of a wiring substrate on which conductive lines of a predetermined shape are formed. Specifically, the transparent conductive film 2 is a flexible film-like wiring substrate that is transparent enough to allow the other side to be seen through. In this embodiment, the transparent conductive film 2 is a film antenna having an antenna made of conductive lines.

[0016] A flexible wiring board 3 is connected to the transparent conductive film 2. The flexible wiring board 3 may be a wiring board having only conductive lines formed thereon and having a wiring function only, or may be a COF (chip on film) on which a semiconductor chip such as a driver IC is mounted.

[0017] As shown in FIG. 1A, the transparent conductive film 2 has a first region, an effective region 2a (active region), and a second region, an ineffective region 2b (inactive region), which is different from the effective region 2a. The effective region 2a is a region located inside the ineffective region 2b. The ineffective region 2b is a region located outside the effective region 2a. In this embodiment, the ineffective region 2b surrounds the effective region 2a. Specifically, the ineffective region 2b is a frame-shaped region (frame region) surrounding the effective region 2a. Therefore, the effective region 2a is a rectangular region. The ineffective region 2b is a peripheral region located at the outer peripheral edge of the transparent conductive film 2.

[0018] The effective area 2a is a transparent area, and the ineffective area 2b is a non-transparent area. Therefore, for example, when the transparent conductive film 2 is placed on a display device of a mobile terminal, the effective area 2a is an area (view area) that can be seen by a user of the mobile terminal, and the ineffective area 2b is an area that is not visible to the user because it is covered by the housing of the mobile terminal or the like. The user can view an image displayed on the display device through the effective area 2a, which is a transparent area, and can operate the mobile terminal by touching the effective area 2a with their finger.

[0019] The effective area 2a is an antenna area in which the antenna 10 (antenna radiation portion) is provided. The antenna 10 is made of conductive wire. In this embodiment, the antenna 10 is a microstrip antenna (patch antenna) made of a microstrip line, which is a fine metal wire with a line width on the order of micrometers. Specifically, the line width of the metal wire that makes up the antenna 10 is 100 μm or less. As an example, the line width of the metal wire that makes up the antenna 10 is 1 μm to 30 μm. The metal wire that makes up the antenna 10 is formed in a predetermined pattern. In this embodiment, the conductive wire that makes up the antenna 10 is formed in a mesh shape. In other words, the antenna 10 is a mesh antenna.

[0020] In this embodiment, the antenna 10 is an assembly of multiple antenna elements 10a. This allows the radiation intensity of the antenna 10 to be increased and allows it to support multiple frequency bands. The multiple antenna elements 10a are formed in different regions within the effective area 2a. In this embodiment, each of the multiple antenna elements 10a is formed in a respective one of multiple island regions 2a1 that are partitioned into island-like regions within the effective area 2a. The multiple island regions 2a1 are formed in a matrix. As an example, the multiple island regions 2a1 are partitioned into 16 regions with 4 rows and 4 columns, as shown in FIG. 1A. In each island region 2a1, the antenna elements 10a are formed in a mesh pattern.

[0021] As shown in the enlarged view of FIG. 1A , the mesh-shaped antenna element 10a includes a plurality of first directional lines extending in a first direction and a plurality of second directional lines extending in a second direction intersecting the first direction. In this embodiment, the first directional lines and the second directional lines are not perpendicular to each other, but they may be perpendicular to each other. Furthermore, each of the plurality of first directional lines is parallel to each other. Similarly, each of the plurality of second directional lines is parallel to each other. The plurality of first directional lines and the plurality of second directional lines are formed on the same plane. Therefore, the plurality of first directional lines and the plurality of second directional lines are integrated at the intersections where the first directional lines and the second directional lines intersect. The first directional lines and the second directional lines may intersect at an intersection such that the first directional lines and the second directional lines do not contact each other at the intersections.

[0022] Furthermore, a first signal line 21 and a first signal terminal 31 are provided in the ineffective region 2b. Each of the first signal line 21 and the first signal terminal 31 is electrically connected to the antenna 10. Specifically, the antenna 10 and the first signal terminal 31 are electrically connected via the first signal line 21. In other words, the first signal line 21 is a connection wiring for connecting the antenna 10 and the first signal terminal 31. Furthermore, the first signal line 21 connected to the antenna 10 functions as a transmission path. Note that the first signal terminal 31 may be a part of the first signal line 21. For example, the first signal terminal 31 may be one end of a conductive wire that constitutes the first signal line 21.

[0023] A plurality of first signal lines 21 are provided. Each of the plurality of first signal lines 21 is connected to each of the plurality of antenna elements 10a. That is, the plurality of first signal lines 21 and the plurality of antenna elements 10a are provided in a one-to-one correspondence. Each of the plurality of first signal lines 21 is formed in a predetermined shape in the ineffective region 2b. The ineffective region 2b is a wiring region in which the first signal lines 21 are routed.

[0024] A plurality of first signal terminals 31 are provided to be connected to the first signal line 21. The number of first signal terminals 31 also corresponds to the number of antenna elements 10a. In other words, there is a one-to-one correspondence between the first signal terminals 31 and the antenna elements 10a.

[0025] The multiple first signal terminals 31 are provided in a connection terminal portion 31a in the ineffective region 2b. Therefore, the multiple first signal lines 21 connected to the multiple first signal terminals 31 are concentrated in the connection terminal portion 31a. Each of the multiple first signal terminals 31 is formed in an elongated shape and extends toward the end of the transparent conductive film 2. The multiple first signal terminals 31 are arranged in parallel.

[0026] The connection terminal portion 31a, which is an area where a plurality of first signal terminals 31 are provided, is a pad portion to which the flexible wiring board 3 is connected. The flexible wiring board 3 is connected to the ineffective area 2b of the transparent conductive film 2. Specifically, the flexible wiring board 3 is connected to the transparent conductive film 2 at the connection terminal portion 31a in the ineffective area 2b.

[0027] The flexible wiring board 3 and the transparent conductive film 2 are joined by a conductive joining member (not shown) such as an anisotropic conductive film (ACF) or solder. In this embodiment, the flexible wiring board 3 and the transparent conductive film 2 are joined by the anisotropic conductive film. In (a) of Figure 1, an ACF region 4a surrounded by a dashed line is the region where the anisotropic conductive film is disposed.

[0028] The flexible wiring board 3 has a second signal line 22 and a second signal terminal 32. The second signal line 22 is made of a conductive wire such as a metal wire, and is electrically connected to the second signal terminal 32. As an example, the second signal line 22 and the second signal terminal 32 are made of copper. The second signal terminal 32 may be a part of the second signal line 22. For example, the second signal terminal 32 may be one end of the conductive wire that constitutes the second signal line 22.

[0029] A plurality of second signal lines 22 and a plurality of second signal terminals 32 are provided. The plurality of second signal lines 22 and the plurality of second signal terminals 32 are provided in a one-to-one correspondence. The plurality of second signal lines 22 are arranged in parallel. The plurality of second signal terminals 32 are also arranged in parallel.

[0030] 1(a) and 1(b), the plurality of second signal terminals 32 face the plurality of first signal terminals 31 of the transparent conductive film 2. The plurality of second signal terminals 32 and the plurality of first signal terminals 31 may be the same in number and provided in one-to-one correspondence, or they may not be the same in number.

[0031] The flexible wiring board 3 also has a substrate layer 50. The substrate layer 50 is a substrate that serves as a base film. Specifically, the substrate layer 50 is a flexible sheet-like film substrate. The substrate layer 50 is a resin layer made of an insulating resin material. For example, the substrate layer 50 is made of polyimide resin, polyester resin, or the like. The second signal line 22 and the second signal terminal 32 are formed on the substrate layer 50. Although not shown, an insulating film may be formed to cover the second signal line 22 and the second signal terminal 32 formed on the substrate layer 50.

[0032] The transparent conductive film 2 and the flexible wiring board 3 are joined with a conductive bonding member such as an anisotropic conductive film, thereby electrically connecting the first signal terminal 31 of the transparent conductive film 2 and the second signal terminal 32 of the flexible wiring board 3. Therefore, although not shown, a conductive bonding member such as an anisotropic conductive film is interposed between the first signal terminal 31 and the second signal terminal 32.

[0033] The flexible wiring board 3 is provided with a connector 5. The connector 5 is provided at an end of the second signal line 22 opposite to the second signal terminal 32 side. A connector of an external device such as a control circuit is connected to the connector 5. The plurality of second signal terminals 32 are electrically connected to the external device such as the control circuit via the connector 5.

[0034] As shown in FIGS. 1B and 1C, the transparent conductive film 2 has a first substrate 41, a second substrate 42, a first ground layer 43, and a second ground layer 44.

[0035] The first substrate 41 has a first surface 41 a and a second surface 41 b facing away from the first surface 41 a. That is, the second surface 41 b is the surface opposite to the first surface 41 a. As shown in FIGS. 1B and 1C, the first surface 41 a is the upper surface of the first substrate 41, and the second surface 41 b is the lower surface of the first substrate 41.

[0036] The first base material 41 has a base material layer 411 and a resin layer 412 laminated on the base material layer 411. In (b) and (c) of Figure 1, the resin layer 412 is disposed above the base material layer 411. In other words, the base material layer 411 is located below the resin layer 412. The upper surface of the resin layer 412 is a first surface 41a which is the upper surface of the first base material 41, and the lower surface of the base material layer 411 is a second surface 41b which is the lower surface of the first base material 41.

[0037] The antenna 10, the first signal line 21, and the first signal terminal 31 are provided on a first substrate 41. In the present embodiment, the antenna 10, the first signal line 21, and the first signal terminal 31 are provided on a first surface 41a of the first substrate 41. Specifically, the antenna 10, the first signal line 21, and the first signal terminal 31 are provided on a resin layer 412 of the first substrate 41. An insulating film may be formed to cover the antenna 10, the first signal line 21, and the first signal terminal 31.

[0038] The base layer 411 is a flexible sheet-like film substrate. The base layer 411 is a light-transmitting substrate that is transmissive to visible light. Specifically, the base layer 411 is a transparent substrate with such high transmittance that the other side can be seen through it.

[0039] The base material layer 411 is made of a resin material. In this embodiment, the base material layer 411 is made of a translucent resin material. Specifically, the base material layer 411 is made of a transparent resin material. The base material layer 411 is also an insulating substrate made of an insulating material. Therefore, the base material layer 411 is made of a transparent insulating resin material. The base material layer 411 is a flat, planar plate with a constant thickness. The top view shape of the base material layer 411 is, for example, rectangular, but is not limited to this.

[0040] Examples of the light-transmitting resin material that can be used to form the base layer 411 include polyethylene terephthalate (PET) resin, polyimide (PI) resin, polyethylene naphthalate (PEN) resin, cycloolefin resin, polycarbonate resin, and acrylic resin. In this embodiment, the base layer 411 is a transparent PET film made of PET. Alternatively, a transparent glass substrate may be used as the base layer 411.

[0041] The resin layer 412 is located above the base material layer 411. In the present embodiment, the resin layer 412 is laminated on one surface of the base material layer 411. Specifically, the resin layer 412 is formed directly on the base material layer 411. Therefore, the upper surface of the base material layer 411 is in contact with the lower surface of the resin layer 412.

[0042] The resin layer 412 is an insulating layer made of an insulating resin material. In the present embodiment, the resin layer 412 is made of an insulating resin material having light-transmitting properties. Specifically, the resin layer 412 is made of a transparent insulating resin material. The resin material making up the resin layer 412 is a thermosetting resin or an ultraviolet-curing resin. Specifically, the resin material making up the resin layer 412 may be, for example, a PET resin, a polyimide resin, a cycloolefin resin, a polycarbonate resin, or an acrylic resin.

[0043] The resin layer 412 is provided with the conductive wires that make up the antenna 10, the first signal line 21, and the first signal terminal 31. The conductive wires that make up the antenna 10 have a smaller line width than the first signal line 21. In other words, the line width of the first signal line 21 is larger than the line width of the conductive wires that make up the antenna 10. This allows the resistance of the first signal line 21 to be reduced. As an example, the line width of the first signal line 21 is 5 μm to 200 μm, and is 20 μm in this embodiment.

[0044] The conductive wires, first signal line 21, and first signal terminal 31 that constitute antenna 10 may be made of the same metal material. For example, the conductive wires, first signal line 21, and first signal terminal 31 that constitute antenna 10 may be copper wiring mainly made of copper. Furthermore, the conductive wires, first signal line 21, and first signal terminal 31 that constitute antenna 10 may be formed in the same process. However, the conductive wires, first signal line 21, and first signal terminal 31 that constitute antenna 10 may be made of different metal materials or may be formed in different processes.

[0045] The conductive wires, first signal line 21, and first signal terminal 31 that constitute antenna 10 are embedded in grooves provided in resin layer 412. The conductive wires, first signal line 21, and first signal terminal 31 that constitute antenna 10 are embedded in the grooves of resin layer 412 so that their upper surfaces are exposed.

[0046] The grooves provided in the resin layer 412 are linear recesses formed so as to indent the surface of the resin layer 412. The resin layer 412 with the grooves provided therein is formed by an imprinting method. That is, the resin layer 412 is an imprinted layer. In this case, the resin layer 412 with the grooves provided therein can be formed by pressing a die member (mold) having protrusions corresponding to the grooves against the resin layer 412. Note that the resin layer 412 with the grooves can also be formed by a method other than the imprinting method. Specifically, the resin layer 412 with the grooves provided therein can be formed by forming a flat resin layer 412 and then forming the grooves in the resin layer 412. For example, the grooves can be formed by cutting out the surface of the flat resin layer 412 using a laser scriber or the like.

[0047] The second substrate 42 faces the first substrate 41. In the present embodiment, the second substrate 42 is disposed on the second surface 41b side of the first substrate 41. Specifically, the second substrate 42 is stacked below the first substrate 41.

[0048] The second substrate 42 has a third surface 42a and a fourth surface 42b facing away from the third surface 42a. That is, the fourth surface 42b is the surface opposite to the third surface 42a. As shown in FIGS. 1B and 1C, the third surface 42a is the upper surface of the second substrate 42, and the fourth surface 42b is the lower surface of the second substrate 42.

[0049] In this embodiment, the first substrate 41 and the second substrate 42 are in contact with each other, and the third surface 42 a of the second substrate 42 is the second surface 41 b of the first substrate 41 .

[0050] The second substrate 42 is a flexible sheet-like film substrate. The second substrate 42 is a light-transmitting substrate that is translucent to visible light. Specifically, the second substrate 42 is a transparent substrate with high transmittance that allows the other side to be seen through. The second substrate 42 has a constant thickness.

[0051] The second substrate 42 is a resin layer made of a resin material. In the present embodiment, the second substrate 42 is made of a light-transmitting resin material. Specifically, the second substrate 42 is made of a transparent resin material. The second substrate 42 is also an insulating substrate made of an insulating material. Therefore, the second substrate 42 is made of a transparent insulating resin material. Examples of the light-transmitting resin material that can be used to make the second substrate 42 include polyethylene terephthalate (PET) resin, polyimide (PI) resin, polyethylene naphthalate (PEN) resin, cycloolefin resin, polycarbonate resin, and acrylic resin.

[0052] Similarly to the first substrate 41, the second substrate 42 may be composed of a substrate layer and a resin layer.

[0053] The first ground layer 43 is provided between the first substrate 41 and the second substrate 42. In the present embodiment, the first ground layer 43 is provided on the first substrate 41. Specifically, the first ground layer 43 is provided on the second surface 41b of the first substrate 41. Note that the second surface 41b of the first substrate 41 is the third surface 42a of the second substrate 42, so it can also be said that the first ground layer 43 is provided on the third surface 42a of the second substrate 42.

[0054] Although the first ground layer 43 is formed so as to be embedded in the base layer 411 of the first base material 41, this is not limiting. For example, the first ground layer 43 may be formed so as to be embedded in the second base material 42. In this case, the second base material 42, which is a resin layer, may be formed on the second surface 41b of the first base material 41 so as to cover the first ground layer 43 formed on the surface of the second surface 41b of the first base material 41. In this way, the first ground layer 43 may be provided on either the first base material 41 or the second base material 42.

[0055] The second ground layer 44 is provided on the second substrate 42. In the present embodiment, the second ground layer 44 is provided on the surface of the second substrate 42 opposite to the first substrate 41 side. Specifically, the second ground layer 44 is provided on the fourth surface 42b of the second substrate 42.

[0056] The first ground layer 43 and the second ground layer 44 are made of a conductive material such as metal. For example, the first ground layer 43 and the second ground layer 44 are copper layers made of copper. The conductive material that makes up the first ground layer 43 and the conductive material that makes up the second ground layer 44 may be the same or different.

[0057] A specific voltage such as a ground potential (earth potential) may be applied to the first ground layer 43 and the second ground layer 44, but no specific voltage may be applied to them. In other words, the first ground layer 43 and the second ground layer 44 may be in an electrically floating state.

[0058] As shown in Fig. 1B, the first ground layer 43 does not face the antenna 10 provided in the effective area 2a. As shown in Fig. 1C, the first ground layer 43 is provided at least in the ineffective area 2b. In plan view, the first ground layer 43 surrounds the antenna 10. Specifically, the first ground layer 43 surrounds all of the antenna elements 10a that make up the antenna 10.

[0059] The first ground layer 43 provided in the ineffective region 2b overlaps the first signal terminal 31 as shown in Fig. 1B, and also overlaps the first signal line 21 as shown in Fig. 1C. In other words, in a plan view, the first ground layer 43 overlaps both the first signal terminal 31 and the first signal line 21.

[0060] The first ground layer 43 may be provided over the entire ineffective region 2b. In this case, the first ground layer 43 may be provided in part of the effective region 2a in addition to the ineffective region 2b. The region where the first ground layer 43 is provided may coincide with the ineffective region 2b. In other words, the region where the first ground layer 43 is provided may be the ineffective region 2b.

[0061] 1B, the second ground layer 44 faces the antenna 10 provided in the effective area 2a. Therefore, the second ground layer 44 is provided in the effective area 2a. In this embodiment, the second ground layer 44 faces all of the antenna elements 10a. In other words, in a plan view, the second ground layer 44 encompasses the entire antenna 10 and overlaps all of the multiple antenna elements 10a. Furthermore, in a plan view, the second ground layer 44 encompasses the first ground layer 43 and overlaps the entire first ground layer 43.

[0062] The second ground layer 44 is preferably provided over at least the entire effective area 2a. In this embodiment, as shown in FIG. 1C, the second ground layer 44 is provided not only in the effective area 2a but also in the ineffective area 2b. For example, the second ground layer 44 may be provided over the entire effective area 2a and the ineffective area 2b. In this case, the second ground layer 44 may be a solid film formed over the entire fourth surface 42b of the second substrate 42. The second ground layer 44 may be provided so as to overlap only the antenna 10. For example, the second ground layer 44 may be formed in an island pattern so as to overlap only the multiple antenna elements 10a. In other words, the antenna elements 10a may be arranged with a gap between them. The second ground layer 44 may also be provided only in the effective area 2a, not in the ineffective area 2b.

[0063] Furthermore, the second ground layer 44 provided in the ineffective region 2b overlaps the first signal terminal 31 as shown in Fig. 1B, and also overlaps the first signal line 21 as shown in Fig. 1C. That is, in plan view, the second ground layer 44 overlaps both the first signal terminal 31 and the first signal line 21, similar to the first ground layer 43. In this way, the first signal terminal 31 and the first signal line 21 overlap both the first ground layer 43 and the second ground layer 44 in plan view.

[0064] Next, the effects of the transparent conductive film 2 according to the present embodiment will be described in comparison with a comparative transparent conductive film 2X shown in Fig. 2. Fig. 2 is a diagram showing the configuration of an antenna module 1X using the comparative transparent conductive film 2X. In Fig. 2, (a) is a plan view of the antenna module 1X, (b) is a cross-sectional view taken along line b-b in (a), and (c) is a cross-sectional view taken along line c-c in (a).

[0065] 2(b) and 2(c), the comparative transparent conductive film 2X includes a transparent substrate 41X including a substrate layer 411X and a resin layer 412X, and a ground layer 43X. An antenna 10, a signal line 21X, and a signal terminal 31X are provided on one surface of the substrate 41X. The ground layer 43X is provided on the other surface of the substrate 41X. The antenna 10 is composed of a plurality of antenna elements 10a, and the plurality of antenna elements 10a and the plurality of signal terminals 31X are electrically connected by a plurality of signal lines 21X.

[0066] In the comparative transparent conductive film 2X configured as described above, in order to suppress crosstalk occurring between the multiple signal lines 21X, it is conceivable to reduce the distance between the signal lines 21X and the ground layer 43X. Specifically, it is conceivable to reduce the thickness of the base material layer 411X to reduce the thickness of the base material 41X.

[0067] However, when the distance between the signal line 21X and the ground layer 43X is reduced, the distance between the antenna 10, which is formed on the same layer as the signal line 21X, and the ground layer 43X also becomes smaller, resulting in a decrease in the antenna efficiency (gain) of the antenna 10.

[0068] As described above, it is difficult for the transparent conductive film 2X of the comparative example to simultaneously suppress crosstalk and maintain or improve antenna efficiency.

[0069] In contrast, the transparent conductive film 2 according to the present embodiment includes a first substrate 41 on which the antenna 10 and the first signal line 21 are provided, a second substrate 42 facing the first substrate 41, a first ground layer 43, and a second ground layer 44. The first ground layer 43 does not face the antenna 10, and the second ground layer 44 faces the antenna 10.

[0070] In this way, by providing the first ground layer 43 and the second ground layer 44 at different positions in the thickness direction, the distance between the antenna 10 and the second ground layer 44 does not become small even if the distance between the first signal line 21 and the first ground layer 43 is reduced. In other words, the distance between the antenna 10 and the second ground layer 44 can be increased while the distance between the first signal line 21 and the first ground layer 43 is reduced.

[0071] This reduces the distance between the first signal lines 21 and the first ground layer 43, thereby suppressing crosstalk between the first signal lines 21, and increases the distance between the antenna 10 and the second ground layer 44, thereby maintaining or improving the antenna efficiency of the antenna 10. In other words, it is possible to achieve both crosstalk suppression and antenna efficiency maintenance or improvement.

[0072] Furthermore, in the transparent conductive film 2 according to the present embodiment, the first signal line 21 overlaps the first ground layer 43 in plan view.

[0073] This configuration can prevent crosstalk from occurring between the first signal lines 21 .

[0074] Furthermore, in the transparent conductive film 2 according to this embodiment, the first signal line 21 overlaps both the first ground layer 43 and the second ground layer 44 .

[0075] This configuration can further suppress the occurrence of crosstalk between the first signal lines 21 .

[0076] In the transparent conductive film 2 according to this embodiment, the second ground layer 44 is provided over at least the entire effective area 2a.

[0077] This configuration can improve the shielding effect of the second ground layer 44. It is more preferable that the second ground layer 44 is provided over the entire effective area 2 a and the ineffective area 2 b. This can further improve the shielding effect of the second ground layer 44.

[0078] Furthermore, in the transparent conductive film 2 according to this embodiment, the antenna 10 is an assembly of multiple antenna elements 10a formed in different regions within the effective region 2a, and the first signal line 21 is composed of multiple first signal lines 21 connected to the multiple antenna elements 10a, and the multiple first signal lines 21 are collected at a connection terminal portion 31a in the ineffective region 2b. In other words, the ends (first signal terminals 31) of the multiple first signal lines 21 are arranged side by side in the ineffective region 2b. In addition, in a plan view, the second ground layer 44 overlaps all of the multiple antenna elements 10a.

[0079] This configuration can improve the shielding effect of the second ground layer 44 for each of the plurality of antenna elements 10a.

[0080] In addition, in the transparent conductive film 2 according to the present embodiment, the first ground layer 43 surrounds the antenna 10 in plan view.

[0081] This configuration can improve the shielding effect of the first ground layer 43 .

[0082] In the transparent conductive film 2 according to this embodiment, the ineffective region 2b is a region located outside the effective region 2a. Specifically, the ineffective region 2b surrounds the effective region 2a.

[0083] This configuration makes it possible to more effectively suppress crosstalk between the first signal lines 21 without reducing the antenna efficiency of the antenna 10 .

[0084] In the transparent conductive film 2 according to the present embodiment, the antenna 10 is formed in a mesh shape.

[0085] This configuration allows the antenna 10 to be easily made transparent, thereby improving the appearance of the transparent conductive film 2.

[0086] In the antenna module 1 shown in FIG. 1, the transparent conductive film 2 includes the second substrate 42 and the second ground layer 44, but the present invention is not limited to this.

[0087] For example, as in the antenna module 1A shown in Fig. 3, the transparent conductive film 2A may not include the second substrate 42 and the second ground layer 44. Fig. 3 is a diagram showing the configuration of a mobile terminal using a transparent conductive film 2A according to a modified example. In Fig. 3, (a) is a cross-sectional view of a portion corresponding to line b-b in Fig. 1, and (b) is a cross-sectional view of a portion corresponding to line c-c in Fig. 1.

[0088] The antenna module 1A of this modification has a structure in which the second substrate 42 and the second ground layer 44 of the transparent conductive film 2 are part of the display device 100 on which the transparent conductive film 2A is provided.

[0089] Specifically, the display device 100 provided with the transparent conductive film 2A includes a display device 101 and a touch sensor film 102 bonded to the display device 101. The touch sensor film 102 includes a transparent substrate 42A and a touch sensor 44A (touch electrode) made of metal and provided on the transparent substrate 42A. In this modification, the transparent substrate 42A functions as the second substrate 42 in the transparent conductive film 2, and the touch sensor 44A functions as the second ground layer 44 in the transparent conductive film 2.

[0090] This modification also achieves the same effects as the transparent conductive film 2 according to the above embodiment. That is, by reducing the distance between the first signal lines 21 and the first ground layer 43, it is possible to suppress crosstalk between the first signal lines 21, and by increasing the distance between the antenna 10 and the touch sensor 44A (second ground layer), it is possible to maintain or improve the antenna efficiency of the antenna 10. That is, it is possible to achieve both crosstalk suppression and antenna efficiency maintenance or improvement.

[0091] Note that the component functioning as the second ground layer 44 in the transparent conductive film 2 is not limited to the touch sensor 44A. As shown in Figures 4 and 5, for example, when a display device 100 includes a display device 101 having a transparent panel and a metal housing 200 or metal plate 201 that holds the display device 101, the transparent panel may function as the second substrate 42 in the transparent conductive film 2, and the metal housing 200 or metal plate 201 may function as the second ground layer 44 in the transparent conductive film 2. This case also provides the same effects as the transparent conductive film 2 according to the above embodiment. In other words, it is possible to achieve both suppression of crosstalk and maintenance or improvement of antenna efficiency.

[0092] For ease of understanding the invention, only a part of the housing 200 is shown in Fig. 4 and only a part of the metal plate 201 is shown in Fig. 5. The actual shape of the housing 200 and the metal plate 201 may be any shape that can hold the display device 101.

[0093] Note that the second ground layer 44 in the transparent conductive film 2 may correspond to a component other than the touch sensor and the housing as long as it is a metal member. Even when the transparent conductive film 2 is mounted on a device other than a display device, by making the second base material 42 correspond to a transparent member and the second ground layer correspond to a metal member, it is possible to suppress crosstalk while maintaining or improving antenna efficiency.

[0094] (Other Modifications) The transparent conductive film and antenna module according to the present disclosure have been described above based on the embodiments, but the present disclosure is not limited to the above-described embodiments.

[0095] For example, in the above embodiment, the conductive wires, first signal line 21, and first signal terminal 31 that constitute antenna 10 are embedded in the grooves of resin layer 412 of first base material 41, but this is not limiting. Specifically, the conductive wires, first signal line 21, and first signal terminal 31 that constitute antenna 10 may be formed on the flat upper surface of resin layer 412 without forming grooves in resin layer 412.

[0096] In the above embodiment, the antenna 10 is a mesh antenna, but this is not limiting, and the antenna 10 may be formed in a pattern other than a mesh.

[0097] In addition, the present disclosure also includes embodiments obtained by applying various modifications to the above-described embodiments that would occur to a person skilled in the art, and embodiments realized by arbitrarily combining the components and functions of the embodiments within the scope of the present disclosure. Furthermore, the present disclosure also includes any combination of two or more claims from among the multiple claims set forth in the claims at the time of filing, within the scope of technical compatibility. For example, when a dependent claim set forth in the claims at the time of filing is made into a multiple claim or multiple multiple claims that cite all of the superordinate claims within the scope of technical compatibility, the present disclosure also includes any combination of all claims included in that multiple claim or multiple multiple claims.

[0098] The transparent conductive film and antenna module according to the present disclosure can be used in various electrical devices such as mobile terminals.

[0099] REFERENCE SIGNS LIST 1, 1A Antenna module 2, 2A Transparent conductive film 2a Effective area 2a1 Island area 2b Ineffective area 3 Flexible wiring board 4a ACF area 5 Connector 10 Antenna 10a Antenna element 21 First signal line 22 Second signal line 31 First signal terminal 31a Connection terminal portion 32 Second signal terminal 41 First substrate 411 Substrate layer 412 Resin layer 41a First surface 41b Second surface 42 Second substrate 42A Transparent substrate 42a Third surface 42b Fourth surface 43 First ground layer 44 Second ground layer 44A Touch sensor 50 Substrate layer 100 Display device 101 Display device 102 Touch sensor film 200 Housing 201 Metal plate

Claims

1. A transparent conductive film having a first region and a second region different from the first region, comprising: a first substrate; an antenna located in the first region and provided on the first substrate; a signal line located in the second region, provided on the first substrate and electrically connected to the antenna; and a first ground layer provided on the first substrate, wherein a second substrate is disposed to face the first substrate, and a second ground layer is provided on the second substrate, the first ground layer does not face the antenna, and the second ground layer faces the antenna.

2. The transparent conductive film according to claim 1, wherein the first substrate has a first surface and a second surface facing away from the first surface, the antenna is provided on the first surface of the first substrate, the signal line is provided on the first surface of the first substrate, the first ground layer is provided on the second surface of the first substrate, the second substrate is disposed on the second surface of the first substrate, and the second ground layer is provided on a fourth surface of the second substrate which is the surface opposite to the third surface in contact with the first substrate.

3. The transparent conductive film according to claim 2, comprising the second substrate and the second ground layer.

4. The transparent conductive film according to claim 3, wherein, in a plan view, the signal line overlaps the first ground layer.

5. The transparent conductive film according to claim 4, wherein the second ground layer is provided over the entire first region.

6. The transparent conductive film according to claim 4 or 5, wherein the first ground layer surrounds the antenna in a plan view.

7. A transparent conductive film according to any one of claims 1 to 5, wherein the antenna is an assembly of a plurality of antenna elements formed in the first region, the plurality of antenna elements are arranged at intervals from one another, the signal line is composed of a plurality of signal lines, each of the plurality of signal lines is connected to a corresponding one of the plurality of antenna elements, and each end of the plurality of signal lines is arranged side by side in the second region.

8. The transparent conductive film according to claim 7, wherein all of the plurality of antenna elements overlap the second ground layer in a plan view.

9. The transparent conductive film according to any one of claims 1 to 5, wherein the second region is located outside the first region in a plan view.

10. The transparent conductive film according to any one of claims 1 to 5, wherein in a plan view, the one region is surrounded by the second region.

11. The transparent conductive film according to any one of claims 1 to 5, wherein the antenna is in the form of a mesh.

12. The transparent conductive film according to claim 1 or 2, wherein the second substrate and the second ground layer are part of a display device in which the transparent conductive film is provided.

13. The transparent conductive film according to claim 12, wherein the display device comprises a display device and a touch sensor film bonded to the display device, the touch sensor film comprises a transparent substrate and a touch sensor made of metal provided on the transparent substrate, the second substrate is the transparent substrate, and the second ground layer is the touch sensor.

14. The transparent conductive film according to claim 12, wherein the display device comprises a display device having a transparent panel, and a metal housing or metal plate that holds the display device, the second substrate is the transparent panel, and the second ground layer is part of the housing or the metal plate.

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