Wiring board and image display device

Abstract

To provide a wiring board and an image display device with which, while suppressing a decrease in the electrical characteristic of a mesh wiring layer, it is possible to make the presence of wirings laid in the surrounding of the mesh wiring layer less likely to be visible.SOLUTION: A wiring board 10 comprises a transparent substrate 11 and a mesh wiring layer 20, the mesh wiring layer 20 including a plurality of first direction wirings 21 and a plurality of second direction wirings 22. When the outer periphery of a region where the mesh wiring layer 20 is disposed is assumed to be a virtual outer periphery line 20S, an end 21e of each first direction wiring 21 and an end 22e of each second direction wiring 22 are connected respectively by an end connection wiring 25 in part of the virtual outer periphery line 20S. When it is assumed that La represents the total length of one side of the virtual outer periphery line in a third direction, and Lp represents the total length of the end connection wiring 25 between both ends 25e, 25e that is included in the total length La, the relationship 0.1 La≤Lp≤0.5 La holds true.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] Embodiments of the present disclosure relate to a wiring board and an image display device.

Background Art

[0002] Currently, high functionality, miniaturization, thinning, and weight reduction of portable terminal devices such as smartphones and tablets are progressing. Since these portable terminal devices use multiple communication bands, a plurality of antennas corresponding to the communication bands are required. For example, a portable terminal device is equipped with a plurality of antennas such as a telephone antenna, a WiFi (Wireless Fidelity) antenna, a 3G (Generation) antenna, a 4G (Generation) antenna, an LTE (Long Term Evolution) antenna, a Bluetooth (registered trademark) antenna, and an NFC (Near Field Communication) antenna However, with the miniaturization of portable terminal devices, the mounting space for antennas is limited, and the degree of freedom in antenna design is narrowing. In addition, since the antenna is built in a limited space, the radio wave sensitivity is not always satisfactory.

[0003] For this reason, a film antenna that can be mounted in the display area of a portable terminal device has been developed. This film antenna is a transparent antenna in which an antenna pattern is formed on a transparent base material, and the antenna pattern is formed by a mesh-shaped conductor mesh layer including a conductor part as a formation part of an opaque conductor layer and a number of openings as non-formation parts.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Incidentally, depending on the relationship between the outer perimeter shape of the conductive mesh layer and the wiring pitch, it is possible that the wiring located on the outer perimeter of the conductive mesh layer may be cut midway. In this case, the electrical characteristics, for example, as an antenna, may deteriorate at the outer perimeter of the conductive mesh layer. To address this, it is conceivable to provide wiring as a boundary line on the outer perimeter of the conductive mesh layer (see, for example, Patent Document 1). In this case, for example, the electrical characteristics as an antenna are maintained, but the wiring located on the outer perimeter of the conductive mesh layer may become conspicuous and easily visible.

[0006] This embodiment provides a wiring board and an image display device that can suppress the deterioration of the electrical characteristics of the mesh wiring layer while making it difficult to visually detect the presence of wiring located on the outer periphery of the mesh wiring layer. [Means for solving the problem]

[0007] Embodiments of this disclosure relate to the following [1] to

[20] .

[0008] [1] A wiring board comprising a transparent substrate and a conductive mesh wiring layer disposed on the substrate, wherein the mesh wiring layer includes a plurality of first-directional wirings and a plurality of second-directional wirings, the plurality of first-directional wirings are each parallel to the first direction, the plurality of second-directional wirings are each parallel to the second direction, when the outer perimeter of the area on which the mesh wiring layer is disposed is defined as a virtual outer perimeter, the virtual outer perimeter is composed of a plurality of straight edges, the virtual outer perimeter forms a closed figure, at least a portion of the virtual outer perimeter extends along a third direction, the first direction and the second direction are each non-parallel to the third direction, in a portion of the virtual outer perimeter, the ends of each first-directional wiring and the ends of each second-directional wiring are each connected by end-connecting wiring, and when the total length of one side of the virtual outer perimeter in the third direction is La, and the total length between the ends of the end-connecting wiring included in the total length La is Lp, the relationship 0.1La ≤ Lp ≤ 0.5La holds.

[0009] [2] The wiring board according to [1], wherein a plurality of the end connecting wires are arranged in a dotted line along the third direction.

[0010] [3] The end connecting wiring is a wiring board according to [1] or [2], extending in a straight line.

[0011] [4] The end connecting wiring is a bent wire shape or a curved shape, as described in [1] or [2].

[0012] [5] The wiring board according to any one of [1] to [4], wherein the wire width of the end connecting wiring is narrower than the wire width of the first direction wiring and the wire width of the second direction wiring.

[0013] [6] The wiring board according to any one of [1] to [5], wherein the pitch of the plurality of first-directional wirings and the pitch of the plurality of second-directional wirings are each 0.01 mm or more and 1 mm or less.

[0014] [7] The wiring board according to any one of [1] to [6], wherein the line width of the first direction wiring and the line width of the second direction wiring are each 0.1 μm or more and 5.0 μm or less.

[0015] [8] A wiring board according to any one of [1] to [7], wherein a dummy wiring layer is provided around the mesh wiring layer, which is electrically independent from the mesh wiring layer.

[0016] [9] The wiring board according to any one of [1] to [8], wherein the mesh wiring layer functions as a millimeter-wave antenna.

[0017]

[10] A wiring board comprising a transparent substrate and a conductive mesh wiring layer disposed on the substrate, wherein the mesh wiring layer includes a plurality of regularly arranged closed figures, each closed figure being surrounded by wiring in two or more directions, and the closed figures located on the outer periphery of the mesh wiring layer have a shape that is enlarged or reduced in part or all of the closed figures located elsewhere on the outer periphery of the mesh wiring layer.

[0018]

[11] The wiring board according to

[10] , wherein two to five of the closed figures counted from the outer peripheral side of the mesh wiring layer have a shape obtained by enlarging or reducing the whole of the closed figures located outside the outer periphery of the mesh wiring layer.

[0019]

[12] The wiring board according to

[10] or

[11] , wherein the closed figure is a polygon.

[0020]

[13] The wiring board according to any one of

[10] to

[12] , wherein the line width of the wiring is 0.1 μm or more and 5.0 μm or less respectively.

[0021]

[14] The wiring board according to any one of

[10] to

[13] , wherein a dummy wiring layer electrically independent of the mesh wiring layer is provided around the mesh wiring layer.

[0022]

[15] The wiring board according to any one of [​​​​​​​​​​​​​​​​

[0027] An image display device comprising a wiring board according to any one of

[20] [1] to

[19] and a display device laminated on the wiring board.

Advantages of the Invention

[0028] According to an embodiment of the present disclosure, it is possible to suppress a decrease in the electrical characteristics of the mesh wiring layer and make it difficult to visually recognize the presence of the wiring located on the outer periphery of the mesh wiring layer.

Brief Description of the Drawings

[0029] [Figure 1] FIG. 1 is a plan1 is a plan view showing an image display device according to a first embodiment. [Figure 2] ​​​​​​​​​​​​​​​​​​​​​​​​​​​​​ [Figure 12] Figure 12 is an enlarged plan view showing the outer periphery of the mesh wiring layer according to a third modification of the first embodiment (enlarged view of section XII in Figure 11). [Figure 13] Figure 13 is an enlarged plan view showing the outer periphery of the mesh wiring layer according to the second embodiment. [Figure 14] Figure 14 is an enlarged plan view showing the outer periphery of the mesh wiring layer according to the first modification of the second embodiment. [Figure 15] Figure 15 is an enlarged plan view showing the outer periphery of the mesh wiring layer according to a second modification of the second embodiment. [Figure 16] Figure 16 is an enlarged plan view showing the outer periphery of the mesh wiring layer according to a third modification of the second embodiment. [Figure 17] Figure 17 is an enlarged plan view showing the outer periphery of the mesh wiring layer according to a fourth modification of the second embodiment. [Figure 18] Figure 18 is an enlarged plan view showing the outer periphery of the mesh wiring layer according to a fourth modification of the second embodiment. [Figure 19] Figures 19(a) and 19(b) are enlarged plan views showing the outer periphery of the mesh wiring layer according to a fifth modification of the second embodiment. [Figure 20] Figures 20(a) and 20(b) are enlarged plan views showing the outer periphery of the mesh wiring layer according to the sixth modified example of the second embodiment. [Figure 21] Figure 21 is an enlarged plan view showing the outer periphery of the mesh wiring layer according to the third embodiment. [Modes for carrying out the invention]

[0030] (First Embodiment) First, the first embodiment will be described with reference to Figures 1 to 6. Figures 1 to 6 are diagrams showing the first embodiment.

[0031] The following figures are schematic representations. Therefore, the size and shape of each part are exaggerated as appropriate for ease of understanding. Furthermore, they can be modified as appropriate without departing from the technical concept. In the following figures, the same parts are denoted by the same reference numerals, and some detailed explanations may be omitted. Also, the numerical values ​​such as dimensions and material names of each component described in this specification are examples of embodiments and are not limited to them; they can be selected and used as appropriate. In this specification, terms that specify shapes and geometric conditions, such as parallel, orthogonal, and perpendicular, are interpreted to include not only their strict meaning but also substantially equivalent states.

[0032] Furthermore, in the following embodiments, "X direction" refers to the direction perpendicular to the longitudinal direction of the mesh wiring layer and perpendicular to the length direction corresponding to the frequency band of the mesh wiring layer. "Y direction" refers to the direction perpendicular to the X direction and parallel to the longitudinal direction of the mesh wiring layer and parallel to the length direction corresponding to the frequency band of the mesh wiring layer. "Z direction" refers to the direction perpendicular to both the X and Y directions and parallel to the thickness direction of the wiring board. Also, "front surface" refers to the surface on the positive Z direction, which is the surface on the substrate where the mesh wiring layer is provided. "Back surface" refers to the surface on the negative Z direction, which is the surface on the substrate opposite to the surface where the mesh wiring layer is provided. In this embodiment, the case in which the mesh wiring layer has a radio wave transmission / reception function (function as an antenna) is described as an example, but the mesh wiring layer 20 does not have to have a radio wave transmission / reception function (function as an antenna).

[0033] [Wiring board configuration] The configuration of the wiring board according to this embodiment will be described with reference to Figures 1 to 5. Figures 1 to 5 are diagrams showing the wiring board according to this embodiment.

[0034] As shown in Figure 1, the wiring board 10 according to this embodiment is placed, for example, on the display device (display) 91 of an image display device 90. Such a wiring board 10 comprises a transparent substrate 11 and a conductive mesh wiring layer 20 placed on the substrate 11. A power supply unit 40 is electrically connected to the mesh wiring layer 20.

[0035] As shown in Figure 2, the mesh wiring layer 20 includes a plurality of first-direction wirings 21 and a plurality of second-direction wirings 22. Each of the plurality of first-direction wirings 21 is parallel to the first direction D1, and each of the plurality of second-direction wirings 22 is parallel to the second direction D2. When the outer perimeter of the area where the mesh wiring layer 20 is arranged is defined as a virtual outer perimeter line 20S, the virtual outer perimeter line 20S is composed of a plurality of linear sides 20X1 to 20X4 and 20Y1 to 20Y4. The virtual outer perimeter line 20S forms a closed figure. A portion of the virtual outer perimeter line 20S extends along a third direction (X direction or Y direction). The first direction D1 and the second direction D2 are non-parallel to the third direction (X direction or Y direction), respectively. In a portion of the virtual outer perimeter line 20S, the ends 21e of each first-direction wiring 21 and the ends 22e of each second-direction wiring 22 are connected by end-connecting wirings 25. Let La be the total length of one side of the virtual outer perimeter of the mesh wiring layer 20 in the third direction (X or Y direction), and let Lp be the total length between the ends of the end-connecting wiring 25 included in the total length La. In this case, the relationship 0.1La ≤ Lp ≤ 0.5La holds.

[0036] The substrate 11 is approximately rectangular in shape when viewed from above. The longitudinal direction of the substrate 11 is parallel to the Y direction, and the short direction of the substrate 11 is parallel to the X direction. The substrate 11 is transparent and approximately flat, and its thickness is approximately uniform overall. The length L1 in the longitudinal direction (Y direction) of the substrate 11 may be in the range of 20 mm to 300 mm, or 100 mm to 200 mm. The length L2 in the short direction (X direction) of the substrate 11 may be in the range of 2 mm to 300 mm, or 3 mm to 100 mm. Furthermore, the length L2 in the short direction (X direction) of the substrate 11 may be in the range of 20 mm to 500 mm, or 50 mm to 100 mm. The corners of the substrate 11 may be rounded.

[0037] The substrate 11 is made of a material that is transparent in the visible light region and has electrical insulating properties. In this embodiment, the substrate 11 is made of polyethylene terephthalate, but is not limited to this. Preferably, the substrate 11 is made of an organic insulating material such as a polyester resin such as polyethylene terephthalate, an acrylic resin such as polymethyl methacrylate, a polycarbonate resin, a polyimide resin, or a polyolefin resin such as cycloolefin polymer, a cellulose resin such as triacetylcellulose, or a fluororesin material such as PTFE or PFA. Depending on the application, glass, ceramics, etc. can also be appropriately selected as the substrate 11 material. In addition, although an example of the substrate 11 being made of a single layer is shown, it is not limited to this, and may be a structure in which multiple substrates or layers are laminated. The substrate 11 may also be in the form of a film or a plate. There are no particular restrictions on the thickness of the substrate 11, and can be appropriately selected depending on the application. As an example, the thickness T1 of the substrate 11 (length in the Z direction, see Figure 4) may be in the range of 10 μm to 200 μm.

[0038] The dielectric loss tangent of the substrate 11 may be 0.002 or less, and preferably 0.001 or less. There is no particular lower limit for the dielectric loss tangent of the substrate 11, but it may be greater than 0. By having the dielectric loss tangent of the substrate 11 within the above range, the loss of gain (sensitivity) associated with the transmission and reception of electromagnetic waves (e.g., millimeter waves) transmitted and received by the mesh wiring layer 20 can be reduced, especially when the electromagnetic waves transmitted and received by the mesh wiring layer 20 are of high frequency. There is no particular lower limit for the dielectric loss tangent of the substrate 11. The relative permittivity of the substrate 11 is not particularly limited, but may be 2.0 or more and 10.0 or less. Having a relative permittivity of 2.0 or more of the substrate 11 allows for a wider range of material choices for the substrate 11. Also, having a relative permittivity of 10.0 or less of the substrate 11 can reduce the loss of gain (sensitivity) associated with the transmission and reception of electromagnetic waves. In other words, when the relative permittivity of the substrate 11 is large, the influence of the thickness of the substrate 11 on the propagation of electromagnetic waves becomes larger. Furthermore, if the propagation of electromagnetic waves is adversely affected, the dielectric loss tangent of the substrate 11 will increase, potentially leading to a significant loss of gain (sensitivity) associated with the transmission and reception of electromagnetic waves. In contrast, by having a relative permittivity of 10.0 or less, the influence of the substrate 11's thickness on the propagation of electromagnetic waves can be reduced. This reduces the loss of gain (sensitivity) associated with the transmission and reception of electromagnetic waves. In particular, when the electromagnetic waves (e.g., millimeter waves) transmitted and received by the mesh wiring layer 20 are of high frequency, the loss of gain (sensitivity) associated with the transmission and reception of electromagnetic waves can be reduced.

[0039] The dielectric loss tangent of substrate 11 can be measured in accordance with IEC 62562. Specifically, first, a test specimen is prepared by cutting out a portion of substrate 11 where the mesh wiring layer 20 is not formed. Alternatively, a portion of substrate 11 with the mesh wiring layer 20 formed on it may be cut out, and the mesh wiring layer 20 may be removed by etching or other means. The dimensions of the test specimen should be 10 mm to 20 mm in width and 50 mm to 100 mm in length. Next, the dielectric loss tangent is measured in accordance with IEC 62562.

[0040] The substrate 11 is transparent. In this specification, transparency means that the transmittance of light rays with wavelengths between 400 nm and 700 nm is 85% or more. The transmittance of visible light of the substrate 11 may be 85% or more, and is preferably 90% or more. There is no particular upper limit to the transmittance of visible light of the substrate 11, but it may be, for example, 100% or less. By setting the transmittance of visible light of the substrate 11 within the above range, the transparency of the wiring board 10 is increased, making the display of the image display device into which the wiring board 10 is incorporated easier to see. Visible light refers to light rays with wavelengths between 400 nm and 700 nm. Furthermore, a transmittance of 85% or more of visible light means that when the absorbance of the substrate 11 is measured using a known spectrophotometer (UV-Vis-Infrared Spectrophotometer: V-670 manufactured by JASCO Corporation), the transmittance is 85% or more in the entire wavelength range between 400 nm and 700 nm. Furthermore, the transmittance of a predetermined area of ​​the wiring board 10 can also be measured using the UV-Vis-Infrared spectrophotometer "V-670" described above. When measuring the transmittance of an area where the mesh wiring layer 20 exists, the measurement should be taken so that the mesh wiring layer 20 is included throughout the measurement range (10 mm × 3 mm) of the UV-Vis-Infrared spectrophotometer.

[0041] In this embodiment, the mesh wiring layer 20 consists of an antenna pattern that functions as an antenna. In Figure 2, one mesh wiring layer 20 is formed on the substrate 11. This mesh wiring layer 20 corresponds to a predetermined frequency band. That is, the length (length in the Y direction) L4 of the mesh wiring layer 20 corresponds to a specific frequency band. The lower the corresponding frequency band, the longer the length L4 of the mesh wiring layer 20. When the wiring board 10 is placed on, for example, the display device 91 (see Figure 1) of an image display device 90, each mesh wiring layer 20 may be part of the wiring board 10 having radio wave transmission and reception functions. The mesh wiring layer 20 may correspond to any of the following: a telephone antenna, a WiFi antenna, a 3G antenna, a 4G antenna, a 5G antenna, an LTE antenna, a Bluetooth® antenna, an NFC antenna, etc. Multiple mesh wiring layers 20 may be formed on the substrate 11. In this case, the lengths of the multiple mesh wiring layers 20 may differ from each other, and each may correspond to a different frequency band. Alternatively, if the wiring board 10 does not have radio wave transmission and reception capabilities, each mesh wiring layer 20 may perform functions such as hovering (a function that allows operation without the user directly touching the display), fingerprint authentication, heating, and noise reduction (shielding).

[0042] The mesh wiring layer 20 has its longitudinal direction parallel to the Y direction and its transverse direction parallel to the X direction. The virtual outer perimeter 20S of this mesh wiring layer 20 is composed of eight linear sides 20X1 to 20X4 and 20Y1 to 20Y4. Of these, sides 20X1 to 20X4 are each parallel to the X direction, and sides 20Y1 to 20Y4 are each parallel to the Y direction. The virtual outer perimeter 20S forms a closed figure. In this embodiment, the virtual outer perimeter 20S constitutes the outline of a figure formed by connecting two rectangles of different sizes. In this specification, "third direction" refers to the direction in which a part of the virtual outer perimeter 20S extends. In this embodiment, "third direction" means either the X direction or the Y direction. At least a part of the virtual outer perimeter 20S extends along the third direction. Specifically, a part of the virtual outer perimeter 20S extends in the X direction, and another part extends in the Y direction.

[0043] In this specification, "virtual outer perimeter 20S" refers to the boundary line that constitutes the outer edge of the mesh wiring layer 20 from a macroscopic perspective. Furthermore, "a part of the virtual outer perimeter 20S" refers to a region of the virtual outer perimeter 20S that has a length of at least a certain amount (1 mm or more). For example, the eight sides 20X1 to 20X4 and 20Y1 to 20Y4 each constitute a part of the virtual outer perimeter 20S. Note that, as shown in Figure 3, "a part of the virtual outer perimeter 20S" does not necessarily have to be on the straight line BL that constitutes the boundary line in a strict sense, but rather refers to a region located within δ = 10 μm in the direction perpendicular to the straight line BL that serves as the reference for the boundary line. Furthermore, "at least a part of the virtual outer perimeter 20S" may be the entire virtual outer perimeter 20S, or only a part of the virtual outer perimeter 20S.

[0044] As shown in Figure 2, the length L4 in the longitudinal direction (Y direction) of the mesh wiring layer 20 may be in the range of, for example, 3 mm to 100 mm. The width W3 in the transverse direction (X direction) of the mesh wiring layer 20 (tip portion 20b) may be in the range of, for example, 1 mm to 10 mm. In particular, the mesh wiring layer 20 may be a millimeter-wave antenna. If the mesh wiring layer 20 is a millimeter-wave antenna, the length L4 of the mesh wiring layer 20 can be selected in the range of 1 mm to 10 mm, more preferably 1.5 mm to 5 mm. Note that Figure 2 shows the shape when the mesh wiring layer 20 functions as a monopole antenna, but it is not limited to this, and can also be a dipole antenna, loop antenna, slot antenna, microstrip antenna, patch antenna, etc.

[0045] The mesh wiring layer 20 has a base end portion 20a on the power supply unit 40 side and a tip end portion 20b connected to the base end portion 20a. The base end portion 20a and the tip end portion 20b each have a roughly rectangular shape in plan view. The base end portion 20a is surrounded by three sides 20Y3, 20X4, and 20Y4. The tip end portion 20b is surrounded by five sides 20X2, 20Y1, 20X1, 20Y2, and 20X3. In this case, the length (Y-direction distance) of the tip end portion 20b is longer than the length (Y-direction distance) of the base end portion 20a. Also, the width (X-direction distance) of the tip end portion 20b is wider than the width (X-direction distance) of the base end portion 20a. The length (Y-direction length) L5 of the base end portion 20a may be 0.1 mm or more and 5 mm or less. The width (length in the Y direction) W4 of the base portion 20a may be 0.1 mm or more and 5 mm or less. The length (length in the Y direction) L6 of the tip portion 20b may be 1 mm or more and 100 mm or less.

[0046] Each mesh wiring layer 20 has metal wires formed in a grid or mesh shape, and has a repeating pattern in the X and Y directions. That is, the mesh wiring layer 20 has a pattern shape composed of a portion extending in the first direction D1 (first direction wiring 21) and a portion extending in the second direction D2 (second direction wiring 22). In this case, the first direction D1 and the second direction D2 are each non-parallel to the third direction. That is, the first direction D1 is not parallel to either the X or Y direction, and the second direction D2 is not parallel to either the X or Y direction. In this embodiment, the first direction D1 is inclined at 45° in both the X and Y directions, and the second direction D2 is also inclined at 45° in both the X and Y directions. The first direction D1 and the second direction D2 are orthogonal to each other.

[0047] As shown in Figure 3, the mesh wiring layer 20 includes a plurality of first directional wirings 21 and a plurality of second directional wirings 22 connected to the plurality of first directional wirings 21. Specifically, the plurality of first directional wirings 21 and the plurality of second directional wirings 22 together form a grid or mesh shape. Each first directional wiring 21 extends in a first direction D1. Each second directional wiring 22 extends in a second direction D2 perpendicular to the first directional wiring 21. The first directional wirings 21 and the second directional wirings 22 together have a length L4 (the length of the mesh wiring layer 20 as described above, see Figure 2) corresponding to a predetermined frequency band, thereby functioning as an antenna. Note that each first directional wiring 21 and each second directional wiring 22 may intersect each other such that the smaller angle is greater than 0° and less than 90°.

[0048] In the mesh wiring layer 20, multiple openings 23 are formed by being surrounded by adjacent first-directional wirings 21 and adjacent second-directional wirings 22. The first-directional wirings 21 and second-directional wirings 22 are arranged at equal intervals from each other. That is, the multiple first-directional wirings 21 are arranged at equal intervals from each other. The pitch P1 of the multiple first-directional wirings 21 may be in the range of 0.01 mm to 1 mm, and is preferably in the range of 0.05 mm to 0.5 mm. The multiple second-directional wirings 22 are also arranged at equal intervals from each other. The pitch P2 of the multiple second-directional wirings 22 may be in the range of 0.01 mm to 1 mm, and is preferably in the range of 0.05 mm to 0.5 mm. In this way, because the multiple first-directional wirings 21 and the multiple second-directional wirings 22 are arranged at equal intervals, there is no variation in the size of the openings 23 within the mesh wiring layer 20, making the mesh wiring layer 20 difficult to see with the naked eye. Furthermore, the pitch P1 of the first directional wiring 21 is equal to the pitch P2 of the second directional wiring 22. Therefore, each opening 23 is approximately square in plan view, and the transparent substrate 11 is exposed from each opening 23. Therefore, by increasing the area of ​​each opening 23, the overall transparency of the wiring board 10 can be increased. The length L3 of one side of each opening 23 may be in the range of 0.01 mm to 1 mm, for example, and is preferably in the range of 0.05 mm to 0.5 mm. Furthermore, it is preferable that the shape and size of the openings 23 be the same across the entire surface except near the virtual outer circumference line 20S, but it is not necessary to make them uniform across the entire surface, for example, by changing them in different locations.

[0049] The opening 23 is surrounded by a pair of first-directional wiring 21 and a pair of second-directional wiring 22. Each first-directional wiring 21 and each second-directional wiring 22 intersect at an intersection 24. There are multiple (in this case, four) intersections 24 around each opening 23.

[0050] As shown in Figure 3, in this embodiment, in a portion of the virtual outer perimeter line 20S, the ends 21e of each first-direction wiring 21 and the ends 22e of each second-direction wiring 22 are connected by end-connecting wiring 25. Specifically, as shown in Figure 3, in the side 20Y1 constituting the virtual outer perimeter line 20S, each first-direction wiring 21 has an end 21e, and each second-direction wiring 22 has an end 22e. The ends 21e of each first-direction wiring 21 and the ends 22e of each second-direction wiring 22 are spaced apart from each other in the Y direction (third direction). The end-connecting wiring 25 connects the ends 21e of adjacent first-direction wiring 21 and the ends 22e of the second-direction wiring 22. Specifically, the end 21e of the first-direction wiring 21 and the end 22e of the second-direction wiring 22 that is closer to that end 21e are connected by the end-connecting wiring 25. In the virtual outer perimeter 20S, it is preferable that multiple end-connecting wires 25 are arranged in a dotted line pattern along the Y direction (third direction). That is, it is preferable that the end-connecting wires 25 exist intermittently along the Y direction (third direction). The end-connecting wires 25 extend in a straight line parallel to the Y direction. The end-connecting wires 25 may also be inclined with respect to the Y direction (third direction) by more than 0° and less than or equal to 10°. The end-connecting wires 25 do not have to be located on the straight line BL that constitutes the virtual outer perimeter 20S, and may be located in a region within δ = 10 μm in the X direction relative to the straight line BL.

[0051] As shown in Figure 2, let La be the total length of one side of the virtual outer perimeter 20S in the Y direction (third direction). Here, the total length La is the length of one of the sides 20X1~20X4 or 20Y1~20Y4 of the virtual outer perimeter 20S in the X direction or the Y direction (third direction), and in this case, it is the total length of side 20Y1. Also, as shown in Figure 3, let Lp be the total length between the ends 25e, 25e of the end connection wiring 25 along side 20Y1 in the Y direction (third direction). Note that the ends 25e, 25e of the end connection wiring 25 coincide with the end 21e of the first direction wiring 21 and the end 22e of the second direction wiring 22, respectively. Here, the total length Lp is the length obtained by summing the lengths Lp1 between the ends 25e, 25e of each end connection wiring 25 over the entire portion of the virtual outer perimeter 20S (side 20Y1) (Lp = ΣLp1). The length Lp1 of each end-connecting wire 25 is the length along the Y direction (third direction) between the center in the line width direction of one end 25e of each end-connecting wire 25 and the center in the line width direction of the other end 25e of each end-connecting wire 25. Note that even if the end-connecting wire 25 is inclined with respect to the Y direction (third direction), the length Lp1 of each end-connecting wire 25 is calculated as the length along the Y direction.

[0052] In this case, the relationship 0.1La ≤ Lp ≤ 0.5La holds between the total length La of a portion of the virtual outer perimeter line 20S and the total length Lp between the two ends 25e, 25e of the end connection wiring 25 along the Y direction (third direction). That is, the end connection wiring 25 exists in a region of 10% to 50% of a portion of the virtual outer perimeter line 20S (for example, side 20Y1). The relationship 0.1La ≤ Lp holds between the total length La and the total length Lp, so that the first direction wiring 21 and the second direction wiring 22 are not interrupted in a portion of the virtual outer perimeter line 20S (for example, side 20Y1). This suppresses a decrease in the electrical characteristics of the mesh wiring layer 20. The relationship Lp ≤ 0.5La holds between the total length La and the total length Lp, so that a portion of the virtual outer perimeter line 20S (side 20Y1) does not become easily visible to the naked eye, and the decrease in visibility can be kept within an acceptable range. Furthermore, it is preferable that the relationship 0.15La ≤ Lp holds between the total length La and the total length Lp, and more preferably that 0.2La ≤ Lp holds. Additionally, it is preferable that the relationship Lp ≤ 0.45La holds between the total length La and the total length Lp, and more preferably that Lp ≤ 0.4La holds.

[0053] Furthermore, within the range where the relationship 0.1La ≤ Lp ≤ 0.5La holds, it is not necessary for some ends 21e of the first direction wiring 21 and some ends 22e of the second direction wiring 22 to be connected by end connecting wiring 25. Also, it is possible for some ends 21e of the first direction wiring 21 and the end 22e of the second direction wiring 22 that is further away from the said end 21e to be connected by end connecting wiring 25. In a part of side 20Y1, there may be ends 21e and 22e that are not connected by end connecting wiring 25.

[0054] Although not shown in the diagram, all or part of the other sides 20X1, 20X2, 20X3, 20Y2, 20Y3, and 20Y4, excluding side 20X4 on the power supply unit 40 side, may also be connected by end connecting wiring 25, with the end 21e of each first-direction wiring 21 and the end 22e of each second-direction wiring 22 being connected respectively. In this case, it is preferable that the relationship 0.1La ≤ Lp ≤ 0.5La holds for each of the sides 20X1, 20X2, 20X3, 20Y2, 20Y3, and 20Y4. Furthermore, let Lat be the total length of the outer perimeter of the mesh wiring layer 20 excluding side 20X4 on the power supply unit 40 side, and Lpt be the total length between the ends 25e, 25e of the end connecting wiring 25 on the entire outer perimeter of the mesh wiring layer 20 excluding side 20X4. In this case, it is preferable that the relationship 0.1Lat ≤ Lpt ≤ 0.5Lat holds.

[0055] Furthermore, for only a portion of each side 20X1, 20X2, 20X3, 20Y1, 20Y2, 20Y3, and 20Y4, the end 21e of each first-direction wiring 21 and the end 22e of each second-direction wiring 22 may be connected by end-connection wiring 25. In this case, it is preferable that the relationship 0.1La ≤ Lp ≤ 0.5La holds for that portion.

[0056] The line width W5 of the end connection wiring 25 may be in the range of 0.1 μm to 5.0 μm, or 0.5 μm to 3.0 μm. Furthermore, the line width W5 of the end connection wiring 25 may be thinner than the line width W1 of the first direction wiring 21 and the line width W2 of the second direction wiring 22, as described later. In this case, the line width W5 of the end connection wiring 25 may be in the range of 0.08 μm to 4.0 μm, or 0.4 μm to 2.4 μm. By making the line width W5 of the end connection wiring 25 thinner than the line width W1 of the first direction wiring 21 and the line width W2 of the second direction wiring 22, the presence of the end connection wiring 25 can be made less visible while maintaining the electrical characteristics of the mesh wiring layer 20.

[0057] As shown in Figure 4, each first-direction wiring 21 has a roughly rectangular or roughly square cross-section perpendicular to its longitudinal direction (cross-section in the second direction D2). In this case, the cross-sectional shape of the first-direction wiring 21 is roughly uniform along its longitudinal direction (first direction D1). Also, as shown in Figure 5, the shape of the cross-section perpendicular to the longitudinal direction (cross-section in the first direction D1) of each second-direction wiring 22 is roughly rectangular or roughly square, and is roughly the same as the cross-sectional shape of the first-direction wiring 21 (cross-section in the second direction D2) described above. In this case, the cross-sectional shape of the second-direction wiring 22 is roughly uniform along its longitudinal direction (second direction D2). The cross-sectional shapes of the first-direction wiring 21 and the second-direction wiring 22 do not necessarily have to be roughly rectangular or roughly square. The cross-sectional shape of the first directional wiring 21 and the second directional wiring 22 may be, for example, a roughly trapezoidal shape where the front side (positive Z-direction side) is narrower than the back side (negative Z-direction side), or a shape in which the sides located on both sides in the longitudinal direction are curved.

[0058] In this embodiment, the line width W1 of the first direction wiring 21 (length in the second direction D2, see Figure 4) and the line width W2 of the second direction wiring 22 (length in the first direction D1, see Figure 5) are not particularly limited and can be appropriately selected depending on the application. For example, the line width W1 of the first direction wiring 21 may be in the range of 0.1 μm to 5.0 μm, or 0.5 μm to 3.0 μm. Similarly, the line width W2 of the second direction wiring 22 may be in the range of 0.1 μm to 5.0 μm, or 0.5 μm to 3.0 μm. Furthermore, the height H1 of the first direction wiring 21 (length in the Z direction, see Figure 4) and the height H2 of the second direction wiring 22 (length in the Z direction, see Figure 5) are not particularly limited and can be appropriately selected depending on the application. The height H1 of the first directional wiring 21 and the height H2 of the second directional wiring 22 may be in the range of, for example, 0.1 μm or more and 5.0 μm or less, or 0.2 μm or more and 2.0 μm or less.

[0059] The material of the first directional wiring 21 and the second directional wiring 22 may be any conductive metallic material. In this embodiment, the material of the first directional wiring 21 and the second directional wiring 22 is copper, but it is not limited to this. For example, the material of the first directional wiring 21 and the second directional wiring 22 may be a metallic material (including alloys) such as gold, silver, copper, platinum, tin, aluminum, iron, or nickel. The first directional wiring 21 and the second directional wiring 22 may also be a plated layer formed by electroplating.

[0060] The overall aperture ratio At of the mesh wiring layer 20 may be 87% or more, 90% or more, or 95% or more. The aperture ratio At may be less than 100%, 98% or less, or 96% or less. By setting the overall aperture ratio At of the wiring board 10 within this range, the conductivity and transparency of the wiring board 10 can be ensured. Note that the aperture ratio refers to the ratio (%) of the area of ​​the opening region (the area where there are no metal parts such as the first direction wiring 21, second direction wiring 22, etc., and the substrate 11 is exposed) to the unit area of ​​a predetermined region (the entire area of ​​the mesh wiring layer 20).

[0061] The sheet resistance of the mesh wiring layer 20 may be 5Ω / □ or less, or 4Ω / □ or less. By keeping the sheet resistance of the mesh wiring layer 20 within the above range, the performance of the mesh wiring layer 20 can be maintained. Specifically, the radiation efficiency of the mesh wiring layer 20 as an antenna (the ratio indicating how much of the power input to the mesh wiring layer 20 is radiated) can be increased. The sheet resistance (Ω / □) of the mesh wiring layer 20 can be determined as follows. That is, the resistance R between both ends of the mesh wiring layer 20 in the longitudinal direction (Y direction) is measured. Next, by dividing this resistance R by the ratio of the length L4 to the width W3 of the mesh wiring layer 20 (L4 / W3), the sheet resistance R of the mesh wiring layer 20 can be obtained. s (Ω / □) can be calculated. That is, the sheet resistance value R s = R × W4 / L3

[0062] Although not shown in the figures, a protective layer may be formed on the surface of the substrate 11 so as to cover the mesh wiring layer 20. The protective layer protects the mesh wiring layer 20 and is formed so as to cover at least the mesh wiring layer 20 of the substrate 11. As the material for the protective layer, a colorless, transparent insulating resin such as polymethyl (meth)acrylate, polyethyl (meth)acrylate, acrylic resins and their modified resins and copolymers, polyester, polyvinyl alcohol, polyvinyl acetate, polyvinyl acetal, polyvinyl butyral, polyvinyl resins and their copolymers, polyurethane, epoxy resin, polyamide, or chlorinated polyolefin can be used.

[0063] A primer layer (not shown) may be formed between the substrate 11 and the mesh wiring layer 20. The primer layer improves the adhesion between the mesh wiring layer 20 and the substrate 11. The primer layer may be provided over substantially the entire surface of the substrate 11. The primer layer may be colorless and transparent. The primer layer may also contain a polymer material. This effectively improves the adhesion between the mesh wiring layer 20 and the substrate 11. Preferably, the primer layer contains an acrylic resin or a polyester resin. This further effectively improves the adhesion with the mesh wiring layer 20. The thickness of the primer layer may be 0.05 μm or more and 0.5 μm or less. By having the primer layer thickness within the above range, the adhesion between the mesh wiring layer 20 and the substrate 11 is improved, while ensuring the transparency of the wiring substrate 10.

[0064] Referring again to Figure 2, the power supply unit 40 is electrically connected to the mesh wiring layer 20. This power supply unit 40 consists of a roughly rectangular conductive thin plate-like member. The longitudinal direction of the power supply unit 40 is parallel to the X direction, and the short direction of the power supply unit 40 is parallel to the Y direction. The power supply unit 40 is located at the longitudinal end (negative Y-direction end) of the substrate 11. The material of the power supply unit 40 can be a metallic material (including alloys) such as gold, silver, copper, platinum, tin, aluminum, iron, or nickel. When the wiring board 10 is incorporated into the image display device 90 (see Figure 1), this power supply unit 40 is electrically connected to the wireless communication circuit 92 of the image display device 90. Although the power supply unit 40 is provided on the surface of the substrate 11, it is not limited to this, and part or all of the power supply unit 40 may be located outside the periphery of the substrate 11. Furthermore, by flexibly forming the power supply unit 40, it may be made possible to wrap around the side or back of the image display device 90 so that it can be electrically connected on the side or back.

[0065] [Manufacturing method for wiring boards] Next, the method for manufacturing a wiring board according to this embodiment will be described with reference to Figures 6(a)-(f). Figures 6(a)-(f) are cross-sectional views showing the method for manufacturing a wiring board according to this embodiment.

[0066] As shown in Figure 6(a), a transparent substrate 11 is prepared.

[0067] Next, a mesh wiring layer 20 is formed on the substrate 11, which includes a plurality of first directional wirings 21 and a plurality of second directional wirings 22 that connect the plurality of first directional wirings 21.

[0068] In this process, first, as shown in Figure 6(b), a metal foil 51 is laminated over substantially the entire surface of the substrate 11. In this embodiment, the thickness of the metal foil 51 may be 0.1 μm or more and 5.0 μm or less. In this embodiment, the metal foil 51 may contain copper.

[0069] Next, as shown in Figure 6(c), a photocurable insulating resist 52 is supplied to substantially the entire surface of the metal foil 51. Examples of photocurable insulating resists 52 include organic resins such as acrylic resins and epoxy resins.

[0070] Next, as shown in Figure 6(d), the insulating layer 54 is formed by photolithography. In this case, the photocurable insulating resist 52 is patterned by photolithography to form the insulating layer 54 (resist pattern). At this time, the insulating layer 54 is formed so that the metal foil 51 corresponding to the first directional wiring 21 and the second directional wiring 22 is exposed.

[0071] Next, as shown in Figure 6(e), the metal foil 51 located on the surface of the substrate 11 that is not covered by the insulating layer 54 is removed. In this process, the metal foil 51 is etched so that the surface of the substrate 11 is exposed by performing a wet treatment using ferric chloride, cupric chloride, strong acids such as sulfuric acid and hydrochloric acid, persulfates, hydrogen peroxide, aqueous solutions thereof, or combinations thereof.

[0072] Next, as shown in Figure 6(f), the insulating layer 54 is removed. In this case, the insulating layer 54 on the metal foil 51 is removed by wet treatment using a permanganate solution, N-methyl-2-pyrrolidone, an acid or alkaline solution, or by dry treatment using oxygen plasma.

[0073] In this way, a wiring board 10 is obtained having a substrate 11 and a mesh wiring layer 20 provided on the substrate 11. In this case, the mesh wiring layer 20 includes first-direction wiring 21, second-direction wiring 22, and end-connecting wiring 25.

[0074] [Operation of this embodiment] Next, we will describe the operation of this embodiment, which has the above configuration.

[0075] As shown in Figure 1, the wiring board 10 according to this embodiment is incorporated into an image display device 90. The image display device 90 has a display device (display) 91. The display device 91 may be, for example, an organic EL (Electro-Luminescence) display device. The display device 91 may include, for example, a metal layer (not shown), a support substrate, a resin substrate, a thin-film transistor (TFT), and an organic EL layer. A touch sensor (not shown) may be placed on the display device 91. Note that the display device 91 is not limited to an organic EL display device. For example, the display device 91 may be another display device that has the function of emitting light itself. The display device 91 may be a micro-LED display device including a micro-LED element (light-emitting element). Also, the display device 91 may be a liquid crystal display device including a liquid crystal. The wiring board 10 is placed directly or indirectly on the display device 91. Examples of such image display devices 90 include mobile terminal devices such as smartphones and tablets. The mesh wiring layer 20 of the wiring board 10 is electrically connected to the wireless communication circuit 92 of the image display device 90 via the power supply unit 40. In this way, radio waves of a predetermined frequency can be transmitted and received via the mesh wiring layer 20, and communication can be performed using the image display device 90. In this embodiment, an image display device 90 is also provided, which includes such a display device 91 and a wiring board 10 arranged on the display device 91.

[0076] In this embodiment, in a portion of the virtual outer perimeter 20S of the mesh wiring layer 20, the ends 21e of each first-direction wiring 21 and the ends 22e of each second-direction wiring 22 are connected by end-connecting wiring 25. Furthermore, let La be the total length of one side of the virtual outer perimeter 20S in the third direction (X or Y direction), and Lp be the total length between the two ends 25e of the end-connecting wiring 25 in the third direction (X or Y direction). In this case, the relationship 0.1La ≤ Lp ≤ 0.5La holds. As a result, even if the virtual outer perimeter 20S does not coincide with the intersection 24 of the mesh wiring layer 20, the ends 21e of each first-direction wiring 21 and the ends 22e of each second-direction wiring 22 are not interrupted. This suppresses a decrease in electrical characteristics on the outer perimeter of the mesh wiring layer 20. On the other hand, if the end 21e of the first directional wiring 21 and the end 22e of the second directional wiring 22 are not connected and are interrupted on the outer periphery of the mesh wiring layer 20, electromagnetic radiation may occur from this point, potentially generating noise of unwanted frequencies.

[0077] Furthermore, according to this embodiment, the end connection wiring 25 is not provided along the entire virtual outer circumference line 20S. As a result, the end connection wiring 25, which faces a direction different from the direction of each first direction wiring 21 and each second direction wiring 22, is less conspicuous. Consequently, the outer circumference of the mesh wiring layer 20 can be made less visible to the naked eye of an observer, and the observer may not be aware of the presence of the mesh wiring layer 20.

[0078] Thus, according to this embodiment, it is possible to improve the electrical characteristics of the mesh wiring layer 20 while suppressing a decrease in the visibility of the mesh wiring layer 20.

[0079] Furthermore, according to this embodiment, multiple end-connecting wires 25 are arranged in a dotted line pattern along a third direction (X direction or Y direction) on the outer periphery of the mesh wiring layer 20. As a result, the end-connecting wires 25 are uniformly arranged along the third direction (X direction or Y direction). Consequently, the end-connecting wires 25 are less conspicuous on the outer periphery of the mesh wiring layer 20, making it difficult for the observer to see the outer periphery of the mesh wiring layer 20 with the naked eye.

[0080] Furthermore, according to this embodiment, the wiring board 10 comprises a transparent substrate 11 and a mesh wiring layer 20 disposed on the substrate 11. Since the mesh wiring layer 20 has a mesh-like pattern consisting of a conductive portion that forms an opaque conductive layer and a large number of openings, the transparency of the wiring board 10 is ensured. As a result, when the wiring board 10 is placed on the display device 91, the display device 91 can be viewed through the openings 23 of the mesh wiring layer 20, and the visibility of the display device 91 is not obstructed.

[0081] [Differentiation] Next, a modified example of the wiring board according to this embodiment will be described.

[0082] (First variation) Figures 7 and 8 show a first modified example of the wiring board. The modified example shown in Figures 7 and 8 differs in the configuration of the end connection wiring 25, but the other configurations are substantially the same as those of the embodiments shown in Figures 1 to 6 described above. In Figures 7 and 8, the same reference numerals are used for parts that are the same as those shown in Figures 1 to 6, and detailed descriptions are omitted.

[0083] In the wiring board 10 shown in Figures 7 and 8, at the edges 20Y1 that constitute the virtual outer perimeter line 20S, the ends 21e of each first-direction wiring 21 and the ends 22e of each second-direction wiring 22 are connected by end-connecting wiring 25. In this case, the end-connecting wiring 25 extends in a non-linear manner.

[0084] As shown in Figure 7, the end connection wiring 25 may have a bent shape. Specifically, the end connection wiring 25 may be V-shaped in plan view. The end connection wiring 25 is located inside the mesh wiring layer 20 beyond side 20Y1. The end connection wiring 25 includes a first wiring portion 25a and a second wiring portion 25b. The first wiring portion 25a may be parallel to the first direction wiring 21. The second wiring portion 25b may be parallel to the second direction wiring 22. In this way, by having a bent shape for the end connection wiring 25, the extension direction of the end connection wiring 25 approaches the extension direction of the first direction wiring 21 or the second direction wiring 22, making the presence of the end connection wiring 25 less visible.

[0085] As shown in Figure 8, the end connection wiring 25 may have a curved shape. Specifically, the end connection wiring 25 may have a semicircular or semi-elliptical shape in plan view. The end connection wiring 25 is located inside the mesh wiring layer 20 beyond the edge 20Y1. In this way, by having a curved shape for the end connection wiring 25, the extension direction of the end connection wiring 25 can be oriented in various directions, making the presence of the end connection wiring 25 less visible.

[0086] In this modified example, the relationship 0.1La ≤ Lp ≤ 0.5La holds between the total length La of one side of the virtual outer circumference line 20S (Figure 2) and the total length Lp between the two ends 25e of the end connecting wiring 25 along the Y direction (third direction). In this case, the length Lp1 of each end connecting wiring 25 refers to the length along the Y direction (third direction) between the center in the line width direction of one end 25e of each end connecting wiring 25 and the center in the line width direction of the other end 25e of each end connecting wiring 25.

[0087] (Second variation) Figures 9 and 10 show a second modified example of the wiring board. The modified example shown in Figures 9 and 10 differs in that a dummy wiring layer 30 is provided around the mesh wiring layer 20; the other configurations are substantially the same as those shown in Figures 1 to 8 described above. In Figures 9 and 10, the same reference numerals are used for parts that are the same as those shown in Figures 1 to 8, and detailed explanations are omitted.

[0088] In the wiring board 10 shown in Figure 9, a dummy wiring layer 30 is provided around the mesh wiring layer 20. Unlike the mesh wiring layer 20, this dummy wiring layer 30 does not substantially function as an antenna.

[0089] As shown in Figure 10, the dummy wiring layer 30 includes a plurality of first-direction dummy wirings 31 and a plurality of second-direction dummy wirings 32. Each first-direction dummy wiring 31 and each second-direction dummy wiring 32 are electrically independent from the mesh wiring layer 20 (first-direction wirings 21 and second-direction wirings 22). The first-direction dummy wirings 31 and second-direction dummy wirings 32 are regularly arranged throughout the entire dummy wiring layer 30. Each first-direction dummy wiring 31 is parallel to the first direction D1 and is located on the extension of each first-direction wiring 21. Each second-direction dummy wiring 32 is parallel to the second direction D2 and is located on the extension of each second-direction wiring 22. The plurality of first-direction dummy wirings 31 are spaced apart from each other in the planar direction and protrude from the substrate 11. The plurality of second-direction dummy wirings 32 are spaced apart from each other in the planar direction and protrude from the substrate 11. Each first-direction dummy wire 31 and each second-direction dummy wire 32 are electrically independent from the mesh wiring layer 20, the power supply section 40, other first-direction dummy wires 31, and other second-direction dummy wires 32. Each first-direction dummy wire 31 and each second-direction dummy wire 32 are linear in plan view. The dummy wiring layer 30 may have additional dummy wires extending in the same direction as the end connection wires 25. These additional dummy wires may extend in a third direction (X or Y direction). Alternatively, the additional dummy wires may extend in the first direction D1 or the second direction D2.

[0090] In this case, each first-direction dummy wiring 31 and each second-direction dummy wiring 32 do not intersect with each other. That is, the dummy wiring layer 30 has a shape in which the region corresponding to the intersection 24 of the mesh wiring layer 20 is missing. This makes it difficult to visually recognize the difference between the mesh wiring layer 20 and the dummy wiring layer 30, and makes the mesh wiring layer 20 placed on the substrate 11 less visible. The aperture ratio of the dummy wiring layer 30 may be the same as or different from the aperture ratio of the mesh wiring layer 20, but it is preferable that it is close to the aperture ratio of the mesh wiring layer 20.

[0091] In this way, by arranging a dummy wiring layer 30 electrically independent of the mesh wiring layer 20 around the mesh wiring layer 20, the outer edge of the mesh wiring layer 20 can be obscured. As a result, the mesh wiring layer 20 can be made less visible on the surface of the image display device 90, making it difficult for users of the image display device 90 to recognize the mesh wiring layer 20 with the naked eye.

[0092] (Third variation) Figures 11 and 12 show a third modified example of the wiring board. The modified examples shown in Figures 11 and 12 differ in that multiple dummy wiring layers 30A and 30B with different aperture ratios are provided around the mesh wiring layer 20, while the other configurations are substantially the same as those shown in Figures 1 to 10 described above. In Figures 11 and 12, the same reference numerals are used for parts that are the same as those shown in Figures 1 to 10, and detailed explanations are omitted.

[0093] In the wiring board 10 shown in Figure 11, multiple (in this case, two) dummy wiring layers 30A and 30B (first dummy wiring layer 30A and second dummy wiring layer 30B) with different aperture ratios are provided around the mesh wiring layer 20. Specifically, the first dummy wiring layer 30A is arranged around the mesh wiring layer 20, and the second dummy wiring layer 30B is arranged around the first dummy wiring layer 30A. The configuration of the first dummy wiring layer 30A may be the same as the configuration of the dummy wiring layer 30 shown in Figures 9 and 10. Unlike the mesh wiring layer 20, the dummy wiring layers 30A and 30B do not substantially function as antennas.

[0094] As shown in Figure 12, the dummy wiring layers 30A and 30B each include a plurality of first-direction dummy wirings 31 and a plurality of second-direction dummy wirings 32. Each first-direction dummy wiring 31 is parallel to the first direction D1 and is located on the extension of each first-direction wiring 21. Each second-direction dummy wiring 32 is parallel to the second direction D2 and is located on the extension of each second-direction wiring 22. Each first-direction dummy wiring 31 and each second-direction dummy wiring 32 are linear in plan view. This makes it difficult to visually recognize the difference between the mesh wiring layer 20 and the first dummy wiring layer 30A, and the difference between the first dummy wiring layer 30A and the second dummy wiring layer 30B, thereby making the mesh wiring layer 20 placed on the substrate 11 less visible.

[0095] In this case, the length of the first-direction dummy wiring 31 of the second dummy wiring layer 30B is shorter than the length of the first-direction dummy wiring 31 of the first dummy wiring layer 30A. Similarly, the length of the second-direction dummy wiring 32 of the second dummy wiring layer 30B is shorter than the length of the second-direction dummy wiring 32 of the first dummy wiring layer 30A. As a result, the aperture ratio of the first dummy wiring layer 30A is greater than the aperture ratio of the mesh wiring layer 20, and the aperture ratio of the first dummy wiring layer 30A is greater than the aperture ratio of the second dummy wiring layer 30B. Alternatively, three or more dummy wiring layers with different aperture ratios may be provided. In this case, it is preferable that the aperture ratio of each dummy wiring layer gradually increases from those closer to the mesh wiring layer 20 to those further away.

[0096] In this way, by arranging dummy wiring layers 30A and 30B that are electrically independent from the mesh wiring layer 20, the outer edge of the mesh wiring layer 20 can be made more indistinct. As a result, the mesh wiring layer 20 can be made less visible on the surface of the image display device 90, making it difficult for users of the image display device 90 to recognize the mesh wiring layer 20 with the naked eye.

[0097] (Second Embodiment) Next, a second embodiment will be described with reference to Figures 13 to 20. Figures 13 to 20 are diagrams showing the second embodiment. In Figures 13 to 20, the same reference numerals are used for parts that are the same as those in the first embodiment shown in Figures 1 to 12, and detailed descriptions are omitted.

[0098] The wiring board 10 according to this embodiment comprises a transparent substrate 11 and a mesh wiring layer 20 disposed on the substrate 11. The mesh wiring layer 20 includes a plurality of regularly arranged closed figures 26. Each closed figure 26 is surrounded by wiring 21, 22 in two or more directions. Closed figures 26 located on the outer periphery of the mesh wiring layer 20 (on the virtual outer periphery line 20S) have a shape that is an enlargement or reduction of part or all of the closed figures 26 located elsewhere on the outer periphery of the mesh wiring layer 20 (on the virtual outer periphery line 20S). As a result, closed figures 26 located on the outer periphery of the mesh wiring layer 20 are located inside the outer periphery of the mesh wiring layer 20 (on the virtual outer periphery line 20S).

[0099] As shown in Figure 13, the mesh wiring layer 20 includes a plurality of regularly arranged closed figures 26. In this case, each closed figure 26 is a polygon, more specifically a quadrilateral such as a square or parallelogram. Each closed figure 26 is composed of a pair of first directional wiring 21 and a pair of second directional wiring 22 arranged to surround the opening 23. In this specification, "closed figure" means a closed figure on the substrate 11 surrounded by wiring consisting of straight lines and / or curves. The mesh wiring layer 20 may be composed of one type of closed figure 26, or it may be composed of multiple types of closed figures 26.

[0100] As shown in Figure 13, in the row of closed figures 26 (hereinafter also referred to as the outer perimeter closed figure 26A) closest to the edge 20Y1 that constitutes the virtual outer perimeter line 20S, the shape differs from the shape of the closed figures 26 in the other rows (hereinafter also referred to as the reference closed figure 26B). That is, the outer perimeter closed figure 26A has a shape that is a scaled-down version of a part of the shape of the reference closed figure 26B. Specifically, among the outer perimeter closed figure 26A, a pair of edges 26s, 26s located on the side closer to edge 20Y1 are deformed toward the inside of the mesh wiring layer 20. The intersection point 24p of the pair of edges 26s, 26s lies on the edge 20Y1 that constitutes the virtual outer perimeter line 20S. Note that the intersection point 24p may be located in a region within δ = 10 μm in the X direction relative to edge 20Y1.

[0101] In Figure 13, assume that the closed figure 26 closest to edge 20Y1 is the reference closed figure 26B (see dashed line in Figure 13). In this case, if the intersection point 24p of the reference closed figure 26B closest to edge 20Y1 is located outside of edge 20Y1, the intersection point 24p may be moved onto edge 20Y1, and a portion of the reference closed figure 26B may be reduced to form the outer perimeter closed figure 26A.

[0102] Other configurations of the wiring board 10 may be the same as those in the first embodiment described above.

[0103] In this embodiment as well, dummy wiring layers 30, 30A, and 30B that are electrically independent from the mesh wiring layer 20 may be provided around the mesh wiring layer 20 (see Figures 9 to 12).

[0104] In this embodiment, the outer peripheral closed figure 26A located on the outer periphery of the mesh wiring layer 20 has a shape that is a reduced portion of the reference closed figure 26B located outside the outer periphery of the mesh wiring layer 20. In this case, the first directional wiring 21 and the second directional wiring 22 are not interrupted on the outer periphery of the mesh wiring layer 20. This suppresses a decrease in electrical characteristics on the outer periphery of the mesh wiring layer 20. Furthermore, the outer peripheral closed figure 26A located on the outer periphery of the mesh wiring layer 20 has a shape similar to the reference closed figure 26B. This makes it difficult for the observer to see the outer periphery of the mesh wiring layer 20 with the naked eye, and prevents the observer from recognizing the presence of the mesh wiring layer 20.

[0105] [Differentiation] Next, a modified example of the wiring board according to this embodiment will be described.

[0106] (First variation) Figure 14 shows a first modified example of the wiring board. In Figure 14, the same reference numerals are used for parts that are the same as those shown in Figure 13, and detailed explanations are omitted.

[0107] In Figure 14, the mesh wiring layer 20 includes a plurality of regularly arranged closed figures 26. On an edge 20Y1 that constitutes the virtual outer perimeter line 20S, the outer perimeter closed figure 26A in the row closest to that edge 20Y1 differs in shape from the reference closed figures 26B in the other rows. That is, the outer perimeter closed figure 26A has a shape that is an enlargement of a part of the shape of the reference closed figure 26B. Specifically, among the outer perimeter closed figures 26A, a pair of edges 26s, 26s located on the side closer to edge 20Y1 are deformed toward the outside of the mesh wiring layer 20. The intersection point 24p of the pair of edges 26s, 26s lies on the edge 20Y1 that constitutes the virtual outer perimeter line 20S. The intersection point 24p may be located in a region within 10 μm in the X direction relative to edge 20Y1.

[0108] In Figure 14, assume that the closed figure 26 closest to edge 20Y1 is the reference closed figure 26B (see dashed line in Figure 14). In this case, if the intersection point 24p of the reference closed figure 26B closest to edge 20Y1 is located inside edge 20Y1, the intersection point 24p may be moved onto edge 20Y1, and a part of the reference closed figure 26B may be enlarged to form the outer perimeter closed figure 26A.

[0109] (Second variation) Figure 15 shows a second modified example of the wiring board. In Figure 15, the same reference numerals are used for parts identical to those shown in Figure 13, and detailed explanations are omitted.

[0110] In Figure 15, the mesh wiring layer 20 includes a plurality of regularly arranged closed figures 26. For each edge 20Y1 constituting the virtual outer perimeter line 20S, the outer perimeter closed figure 26A in the row closest to that edge 20Y1 differs in shape from the reference closed figures 26B in the other rows. That is, the outer perimeter closed figure 26A has a shape that is a scaled-down version of the reference closed figure 26B. Specifically, the outer perimeter closed figure 26A closest to edge 20Y1 is scaled down in the X direction relative to the reference closed figure 26B. One intersection point 24p of the outer perimeter closed figure 26A lies on edge 20Y1 constituting the virtual outer perimeter line 20S. The intersection point 24p may be located within a region of 10 μm or less in the X direction relative to edge 20Y1. Furthermore, a pair of edges 26s1, 26s1 of the outer perimeter closed figure 26A second closest to edge 20Y1 are deformed toward the inside of the mesh wiring layer 20.

[0111] In Figure 15, assume that the closed figure 26 closest to edge 20Y1 is the reference closed figure 26B (see dashed line in Figure 15). In this case, if the intersection point 24p of the reference closed figure 26B closest to edge 20Y1 is located outside of edge 20Y1, the intersection point 24p may be moved onto edge 20Y1, and the entire reference closed figure 26B may be reduced in size to become the outer perimeter closed figure 26A.

[0112] (Third variation) Figure 16 shows a third modified example of the wiring board. In Figure 16, the same reference numerals are used for parts identical to those shown in Figure 13, and detailed explanations are omitted.

[0113] In Figure 16, the mesh wiring layer 20 includes a plurality of regularly arranged closed figures 26. For each edge 20Y1 constituting the virtual outer perimeter line 20S, the outer perimeter closed figure 26A in the row closest to that edge 20Y1 differs in shape from the reference closed figures 26B in the other rows. That is, the outer perimeter closed figure 26A has a shape that is an enlargement of the entire shape of the reference closed figure 26B. Specifically, the outer perimeter closed figure 26A closest to edge 20Y1 is enlarged in the X direction relative to the reference closed figure 26B. One intersection point 24p of the outer perimeter closed figure 26A lies on edge 20Y1 constituting the virtual outer perimeter line 20S. The intersection point 24p may be located within a region of 10 μm or less in the X direction relative to edge 20Y1. Furthermore, a pair of edges 26s1, 26s1 of the outer perimeter closed figure 26A second closest to edge 20Y1 are deformed toward the outside of the mesh wiring layer 20.

[0114] In Figure 16, assume that the closed figure 26 closest to edge 20Y1 is the reference closed figure 26B (see dashed line in Figure 16). In this case, if the intersection point 24p of the reference closed figure 26B closest to edge 20Y1 is located inside edge 20Y1, the intersection point 24p may be moved onto edge 20Y1, and the entire reference closed figure 26B may be enlarged to become the perimeter closed figure 26A.

[0115] (Fourth variation) Figures 17 and 18 show a fourth modified example of the wiring board. In Figures 17 and 18, the same reference numerals are used for parts identical to those shown in Figure 13, and detailed descriptions are omitted.

[0116] In Figures 17 and 18, the mesh wiring layer 20 includes a plurality of regularly arranged closed figures 26. On edge 20Y1 that constitutes the virtual outer perimeter line 20S, two (two rows) of outer perimeter closed figures 26A, counted from the outer perimeter side (the virtual outer perimeter line 20S side), have a different shape from the reference closed figure 26B of the other row. That is, the two outer perimeter closed figures 26A, counted from the outer perimeter side, have a shape that is either a scaled-down version (Figure 17) or an enlarged version (Figure 18) of the overall shape of the reference closed figure 26B. Specifically, the two rows of outer perimeter closed figures 26A, counted from the edge 20Y1 side, are scaled down (Figure 17) or enlarged (Figure 18) in the X direction relative to the reference closed figure 26B. One intersection point 24p of the outer perimeter closed figure 26A closest to edge 20Y1 lies on edge 20Y1 that constitutes the virtual outer perimeter line 20S. The intersection point 24p may be located within a region of 10 μm or less in the X direction relative to edge 20Y1. Furthermore, the pair of edges 26s1, 26s1 of the outer perimeter closed figure 26A that is third closest to edge 20Y1 are deformed toward the inside (Figure 17) or outside (Figure 18) of the mesh wiring layer 20.

[0117] In Figures 17 and 18, assume that the closed figure 26 closest to edge 20Y1 is the reference closed figure 26B (see dashed lines in Figures 17 and 18). In this case, if the intersection point 24p of the reference closed figure 26B closest to edge 20Y1 is located outside of edge 20Y1 (Figure 17), move the intersection point 24p onto edge 20Y1. This may reduce the size of the first and second outer perimeter closed figures 26A from the outer edge. Alternatively, if the intersection point 24p of the reference closed figure 26B closest to edge 20Y1 is located inside of edge 20Y1 (Figure 18), move the intersection point 24p onto edge 20Y1. This may enlarge the size of the first and second outer perimeter closed figures 26A from the outer edge.

[0118] In this modified example, three to five outer-peripheral closed figures 26A, counted from the outer edge, may have a shape that is a scaled-down or enlarged version of the standard closed figure 26B. By scaling down or enlarging two or more closed figures 26 from the outer edge in this way, the amount of deformation of each individual closed figure 26 is suppressed. This suppresses a decrease in the visibility of the mesh wiring layer 20, making it difficult for observers to recognize the presence of the mesh wiring layer 20. Furthermore, by scaling down or enlarging five or fewer closed figures 26 from the outer edge, the number of outer-peripheral closed figures 26A with a different shape from the standard closed figure 26B is reduced, thereby suppressing a decrease in the electrical characteristics of the mesh wiring layer 20.

[0119] (Fifth variation) Figures 19(a) and 19(b) show a fifth modified example of the wiring board. In Figures 19(a) and 19(b), the same reference numerals are used for parts identical to those shown in Figure 13, and detailed explanations are omitted.

[0120] In Figures 19(a) and 19(b), the mesh wiring layer 20 includes a plurality of regularly arranged closed shapes 26. Each closed shape 26 is a rectangle or a square. In this case, each first directional wiring 21 extends parallel to the Y direction, and each second directional wiring 22 extends parallel to the X direction. On an edge 20Y1 that constitutes the virtual outer perimeter line 20S, the outer perimeter closed shape 26A in the row closest to that edge 20Y1 differs in shape from the reference closed shapes 26B in the other rows. That is, the outer perimeter closed shape 26A has a shape that is a scaled-down version of the reference closed shape 26B (Figure 19(a)) or an enlarged version (Figure 19(b)). Specifically, among the outer perimeter closed shapes 26A, the first directional wiring 21 located on the side closer to edge 20Y1 lies on edge 20Y1 that constitutes the virtual outer perimeter line 20S. Note that the first directional wiring 21 may be located within a region of 10 μm or less in the X direction relative to edge 20Y1.

[0121] In Figures 19(a) and 19(b), assume that the closed figure 26 closest to edge 20Y1 is the reference closed figure 26B (see dashed lines in Figures 19(a) and 19(b)). In this case, if the first directional wiring 21 closest to edge 20Y1 is located outside of edge 20Y1 (Figure 19(a)), the first directional wiring 21 may be moved onto edge 20Y1, and the entire reference closed figure 26B including the first directional wiring 21 may be reduced in size to form the outer perimeter closed figure 26A. Alternatively, if the first directional wiring 21 closest to edge 20Y1 is located inside of edge 20Y1 (Figure 19(b)), the first directional wiring 21 may be moved onto edge 20Y1, and the entire reference closed figure 26B including the first directional wiring 21 may be enlarged to form the outer perimeter closed figure 26A.

[0122] (Sixth variation) Figures 20(a) and 20(b) show a sixth modified example of the wiring board. In Figures 20(a) and 20(b), the same reference numerals are used for parts identical to those shown in Figure 13, and detailed explanations are omitted.

[0123] In Figures 20(a) and 20(b), the mesh wiring layer 20 includes a plurality of regularly arranged closed figures 26. Each closed figure 26 is a polygon, more specifically a 12-sided concave polygon. In this case, each closed figure 26 is surrounded by 12 wires 21w. On an edge 20Y1 that constitutes the virtual outer perimeter line 20S, the outer perimeter closed figure 26A in the row closest to that edge 20Y1 has a different shape from the reference closed figures 26B in the other rows. That is, the outer perimeter closed figure 26A has a shape that is a scaled-down version of the reference closed figure 26B (Figure 20(a)) or an enlarged version (Figure 20(b)). Specifically, the two intersection points 24p of the outer perimeter closed figure 26A lie on the edge 20Y1 that constitutes the virtual outer perimeter line 20S. The intersection points 24p may also be located within a region of 10 μm or less in the X direction relative to the edge 20Y1.

[0124] In Figures 20(a) and 20(b), assume that the closed figure 26 closest to edge 20Y1 is the reference closed figure 26B (see dashed lines in Figures 20(a) and 20(b)). In this case, if the intersection point 24p closest to edge 20Y1 is located outside of edge 20Y1 (Figure 20(a)), the intersection point 24p may be moved onto edge 20Y1, and the entire reference closed figure 26B including the intersection point 24p may be reduced in size to form the perimeter closed figure 26A. Alternatively, if the intersection point 24p closest to edge 20Y1 is located inside of edge 20Y1 (Figure 20(b)), the intersection point 24p may be moved onto edge 20Y1, and the entire reference closed figure 26B including the intersection point 24p may be enlarged to form the perimeter closed figure 26A.

[0125] (Third embodiment) Next, a third embodiment will be described with reference to Figure 21. Figure 21 is a diagram showing the outer periphery of the mesh wiring layer according to the third embodiment. In Figure 21, the same reference numerals are used for parts that are the same as those in the first embodiment shown in Figures 1 to 12 and the second embodiment shown in Figures 13 to 20, and detailed descriptions are omitted.

[0126] The wiring board 10 according to this embodiment comprises a transparent substrate 11 and a mesh wiring layer 20 disposed on the substrate 11. The mesh wiring layer 20 includes a plurality of irregularly arranged closed figures 26. Each closed figure 26 is surrounded by wiring 21w in two or more directions. Closed figures 26 located on the outer periphery of the mesh wiring layer 20 (on the virtual outer periphery line 20S) are located inside the outer periphery of the mesh wiring layer 20 (virtual outer periphery line 20S).

[0127] As shown in Figure 21, the mesh wiring layer 20 includes a plurality of irregularly arranged closed shapes 26. In this case, each closed shape 26 is a polygon, more specifically, an irregular quadrilateral. The closed shapes 26 may also be polygons other than quadrilaterals. Each closed shape 26 is composed of a plurality of wires 21w arranged to surround the perimeter of the opening 23.

[0128] As shown in Figure 21, for an edge 20Y1 that constitutes the virtual outer perimeter 20S, the intersection point 24p of the closed figure 26 closest to that edge 20Y1 lies on the straight line BL that constitutes the virtual outer perimeter 20S. Note that the intersection point 24p may also be located within a region of δ = 10 μm in the X direction relative to edge 20Y1.

[0129] Other configurations of the wiring board 10 may be the same as those in the first and second embodiments described above.

[0130] In this embodiment, the closed figures 26 located on the outer periphery of the mesh wiring layer 20 are located inward from the outer periphery of the mesh wiring layer 20. In this case, the wiring 21w is not interrupted on the outer periphery of the mesh wiring layer 20. This suppresses a decrease in electrical characteristics on the outer periphery of the mesh wiring layer 20. Furthermore, the multiple closed figures 26 located on the outer periphery of the mesh wiring layer 20 have irregular shapes. This makes it difficult for the observer to see the outer periphery of the mesh wiring layer 20 with the naked eye, and prevents the observer from recognizing the presence of the mesh wiring layer 20.

[0131] The multiple components disclosed in the above embodiments and variations can be combined as needed. Alternatively, some components may be removed from all the components shown in the above embodiments and variations. [Explanation of Symbols]

[0132] 10 Wiring board 11 circuit boards 20 mesh wiring layers 20S Virtual Outer Boundary Line 21 1st direction wiring 21e end 22 2nd direction wiring 22e end 23 Opening 24 intersection 25 End connection wiring 25e end 26 Closed Figures 40 Power supply section 90 Image display device

Claims

1. A transparent substrate, The substrate comprises a conductive mesh wiring layer disposed on the substrate, The mesh wiring layer includes a plurality of first-directional wirings and a plurality of second-directional wirings. The plurality of first-direction wirings are each parallel to the first direction, The aforementioned plurality of second-direction wirings are each parallel to the second direction, When the outer perimeter of the region where the mesh wiring layer is arranged is defined as a virtual outer perimeter, the virtual outer perimeter is composed of a plurality of straight edges, and the virtual outer perimeter forms a closed figure. At least a portion of the aforementioned virtual outer perimeter extends along the third direction, The first and second directions are each non-parallel to the third direction, In a portion of the aforementioned virtual outer perimeter, the ends of each first-direction wiring and the ends of each second-direction wiring are connected by end-connection wiring. When the total length of one side of the virtual outer perimeter in the third direction is La, and the total length between the two ends of the end-connecting wiring included in the total length La is Lp, 0.1La≦Lp≦0.5La A wiring board where the following relationship holds true.

2. The wiring board according to claim 1, wherein a plurality of end-connecting wirings are intermittently present along the third direction in a region of 10 μm or less on the straight line constituting the virtual outer perimeter, or in a direction perpendicular to the third direction with respect to the straight line.

3. The end connection wiring extends in a straight line, as described in claim 1.

4. The wiring board according to claim 1, wherein the end connecting wiring has a bent or curved shape.

5. The wiring board according to claim 1, wherein the wire width of the end connecting wiring is narrower than the wire width of the first direction wiring and the wire width of the second direction wiring.

6. The wiring board according to claim 1, wherein the pitch of the plurality of first-directional wirings and the pitch of the plurality of second-directional wirings are each 0.01 mm or more and 1 mm or less.

7. The wiring board according to claim 1, wherein the line width of the first directional wiring and the line width of the second directional wiring are each 0.1 μm or more and 5.0 μm or less.

8. The wiring board according to claim 1, wherein a dummy wiring layer is provided around the mesh wiring layer, electrically independent from the mesh wiring layer.

9. The wiring board according to claim 1, wherein the mesh wiring layer functions as a millimeter-wave antenna.

10. A wiring board according to any one of claims 1 to 9, The system comprises a display device laminated on the aforementioned wiring board, An image display device in which the wiring board is positioned on the observer side relative to the display device.

Images