JP7623404B2 - Conductive film and display device - Google Patents

Description

The present invention relates to a conductive film and a display device.

In some display devices, such as liquid crystal display devices, a conductive member having a conductor portion formed of thin metal wires and having a pattern including openings is used. In such cases, in order to prevent the boundary between the portion where the conductor portion is provided and the portion where the conductor portion is not provided from being visible, thin metal wires that form a mesh-like pattern as a dummy member are generally provided throughout the entire image display area in addition to the conductor portion that actually functions as a conductor (for example, Patent Document 1).

International Publication No. 2019/093049

When fine metal wires forming a mesh-like pattern as dummy members are provided over the entire image display section, moire may occur in the displayed image due to interference between the fine metal wires and the pixels of the display device. Therefore, from the viewpoint of suppressing moire, it is considered effective to incorporate a conductive film having a film-like substrate and a conductor portion having a pattern including an opening, and in which fine metal wires as dummy members are not provided in areas other than the conductor portion, into the display device. In particular, a conductive film further having an insulating resin portion that fills the openings of the conductor portion is expected to be easy to manufacture. However, in that case, due mainly to the difference between the refractive index of the insulating resin portion and the refractive index of air, a difference occurs in the optical path length between the light that passes through the insulating resin portion and the light that passes through the other portions, which may cause problems in normal image display.

Therefore, the present invention provides a conductive film that, when incorporated into a display device, suppresses the occurrence of moire in the displayed image and makes it easy to ensure a highly uniform optical path length.

The present invention provides a conductive film comprising a film-like light-transmitting substrate, a conductive layer provided on a first region occupying a part of one of the main surfaces of the light-transmitting substrate, and a light-transmitting resin layer provided so as to cover the entire second region of one of the main surfaces of the light-transmitting substrate, including the region other than the first region. The conductive layer has a conductor portion including a portion having a pattern including an opening that extends in the in-plane direction of the main surface of the light-transmitting substrate, and an insulating resin portion that fills the opening of the conductor portion.

The above-mentioned conductive film has a light-transmitting resin layer provided over the entire second region, including regions other than the first region in which the conductive layer including the insulating resin portion is provided. Therefore, when this is incorporated into a display device, the occurrence of moire caused by the dummy member is suppressed, and a highly uniform optical path length for the light that displays an image is easily ensured.

The area of the first region may be smaller than the area of the second region. When the area of the first region is relatively small, the conductor portion can be provided while minimizing the effect on the image display.

The pattern including the openings of the conductor may be a mesh pattern. The conductor portion having the mesh pattern can function well as, for example, a radiating element of an antenna.

The transparent resin layer and the insulating resin portion may be a cured product of a curable resin composition. A conductive film having a transparent resin layer and an insulating resin portion made of a curable resin composition tends to have good light transmittance and is easy to manufacture.

The transparent resin layer and the insulating resin portion may be formed from the same resin. Since the transparent resin layer and the insulating resin portion formed from the same resin have the same refractive index, the optical path length passing through the conductive film can be further stabilized. From the same viewpoint, the conductor portion, the insulating resin portion, and the light-transmitting resin layer may have substantially the same thickness.

The difference between the refractive index of the light-transmitting substrate and the refractive index of the light-transmitting resin layer may be 0.1 or less. This makes it easier to ensure good visibility of the displayed image.

Another aspect of the present invention provides a display device comprising the above-mentioned conductive film.

When incorporated into a display device, the conductive film of one aspect of the present invention can suppress the occurrence of moire in the displayed image while ensuring high uniformity in the optical path length.

FIG. 1 is a plan view illustrating an embodiment of a conductive film. 2 is a cross-sectional view taken along line II-II in FIG. FIG. 2 is a plan view illustrating an example of a conductive layer. FIG. 2 is an enlarged cross-sectional view showing a portion of an example of a conductive layer. FIG. 1 is a cross-sectional view showing an embodiment of a display device.

Several embodiments of the present invention are described in detail below. However, the present invention is not limited to the following embodiments.

1 is a plan view showing one embodiment of a conductive film, and FIG. 2 is a cross-sectional view taken along line II-II in FIG. 1. The conductive film 20 shown in FIGS. 1 and 2 comprises a film-like light-transmitting substrate 1, a conductive layer 5 provided on a first region SA occupying a part of one main surface 1S of the light-transmitting substrate 1, and a light-transmitting resin layer 7B provided so as to cover the entire second region SB including the region other than the first region SA of one main surface 1S of the light-transmitting substrate 1. The conductive layer 5 has a conductor portion 3 including a portion having a pattern including a plurality of openings 3a extending in the in-plane direction of the main surface 1S of the light-transmitting substrate 1, and an insulating resin portion 7A filling the openings 3a of the conductor portion 3.

The first region SA is a portion of the main surface 1S of the light-transmitting substrate 1 corresponding to the range indicated by A in FIG. 2, and a conductive layer 5 is provided therein. The second region SB is a portion of the main surface 1S of the light-transmitting substrate 1 corresponding to the range indicated by B in FIG. 2, and a light-transmitting resin layer 7B is provided therein. A closed line along the side surface of the conductor portion 3 that is located on the outermost side when viewed from a direction perpendicular to the main surface 1S can be regarded as the outer edge of the first region SA. As shown in FIG. 2, the light-transmitting resin layer 7B may be adjacent to the side surface of the conductor portion 3 located on the outer edge of the first region SA.

In the case of the conductive film 20 illustrated in FIG. 1 and FIG. 2, the entire portion of the main surface 1S of the light-transmitting substrate 1 excluding the first region SA is the second region SB, and the light-transmitting resin layer 7B is provided so as to cover the entire second region SB. However, the main surface 1S of the light-transmitting substrate 1 may also include a portion other than the first region SA and the second region SB, that is, a region in which the conductive layer 5 and the light-transmitting resin layer 7B are not provided. For example, there may be a region around the second region SB in which the conductive layer 5 and the light-transmitting resin layer 7B are not provided. The second region SB may include a region that corresponds to the image display region of the display device when the conductive film 20 is incorporated into the display device. The total ratio of the first region SA and the second region SB to the main surface 1S of the light-transmitting substrate 1 may be, for example, 80 to 100 area%, 90 to 100 area%, 95 to 100 area%, or 100 area%.

The area of the first region SA may be smaller than the area of the second region SB. When the area of the first region SA is relatively small, the conductive layer 5 can be provided while reducing the influence on image display. From the same viewpoint, the ratio of the area of the first region SA, i.e., the area of the conductive layer 5, to the area of the main surface 1S of the light-transmitting substrate 1 may be 30 area% or less, 20 area% or less, 10 area% or less, or 5 area% or less, or may be 1 area% or more. The position of the first region SA on the main surface 1S of the light-transmitting substrate 1 is not particularly limited, but as exemplified in Figures 1 and 2, the first region SA may be disposed near the outer edge of the main surface 1S, and the second region SB may include the center of the main surface 1S.

The light-transmitting substrate 1 has a degree of light transparency required when the conductive film 20 is incorporated into a display device. Specifically, the total light transmittance of the light-transmitting substrate 1 may be 90 to 100%. The haze of the light-transmitting substrate 1 may be 0 to 5%.

The light-transmitting substrate 1 may be, for example, a transparent resin film, examples of which include a film of polyethylene terephthalate (PET), polycarbonate (PC), polyethylene naphthalate (PEN), cycloolefin polymer (COP), or polyimide (PI). Alternatively, the light-transmitting substrate 1 may be a glass substrate.

The light-transmitting substrate 1 may be a laminate having a light-transmitting support film and an underlayer provided on the support film. The support film may be the transparent resin film described above. The underlayer is a layer provided for forming the conductor portion 3 by electroless plating or the like. When the conductor portion 3 is formed by another method, the underlayer does not necessarily have to be provided.

The thickness of the light-transmitting substrate 1 or the supporting film constituting it may be 10 μm or more, 20 μm or more, or 35 μm or more, and may be 500 μm or less, 200 μm or less, or 100 μm or less.

The underlayer may be a layer containing a catalyst and a resin. The resin may be a cured product of a curable resin composition. Examples of the curable resin contained in the curable resin composition include amino resins, cyanate resins, isocyanate resins, polyimide resins, epoxy resins, oxetane resins, polyesters, allyl resins, phenolic resins, benzoxazine resins, xylene resins, ketone resins, furan resins, COPNA resins, silicon resins, dicyclopentadiene resins, benzocyclobutene resins, episulfide resins, ene-thiol resins, polyazomethine resins, polyvinylbenzyl ether compounds, acenaphthylene, and ultraviolet-curable resins containing unsaturated double bonds, as well as functional groups that undergo a polymerization reaction under ultraviolet light, such as cyclic ethers and vinyl ethers. A resin layer that improves the adhesion between the light-transmitting substrate 1 and the underlayer and the underlayer containing the catalyst and resin may be provided between the light-transmitting substrate 1 and the underlayer.

The catalyst contained in the underlayer may be an electroless plating catalyst. The electroless plating catalyst may be a metal selected from Pd, Cu, Ni, Co, Au, Ag, Pd, Rh, Pt, In, and Sn, or may be Pd. The catalyst may be one type alone or a combination of two or more types. Typically, the catalyst is dispersed in the resin as catalyst particles.

The catalyst content in the undercoat layer may be 3% by mass or more, 4% by mass or more, or 5% by mass or more, and may be 50% by mass or less, 40% by mass or less, or 25% by mass or less, based on the total amount of the undercoat layer.

The thickness of the underlayer may be 10 nm or more, 20 nm or more, or 30 nm or more, and may be 500 nm or less, 300 nm or less, or 150 nm or less.

The conductor portion 3 constituting the conductive layer 5 includes a portion having a pattern including openings 3a. The pattern including openings 3a may be a mesh-like pattern including a plurality of regularly arranged openings 3a formed by a plurality of linear portions intersecting each other. The conductor portion 3 having a mesh-like pattern can function well, for example, as a radiating element of an antenna. In addition to the portion having a pattern including openings 3a, the conductor portion 3 may have a portion corresponding to a conductive member such as a ground terminal or a power supply terminal.

The conductor portion 3 may contain a metal. The conductor portion 3 may contain at least one metal selected from copper, nickel, cobalt, palladium, silver, gold, platinum, and tin, or may contain copper. The conductor portion 3 may be a metal plating formed by a plating method. The conductor portion 3 may further contain a non-metallic element such as phosphorus to the extent that appropriate conductivity is maintained.

The insulating resin part 7A is arranged to fill the opening 3a of the conductor part 3, and the insulating resin part 7A and the conductor part 3 may form a flat surface.

The light-transmitting resin layer 7B is formed of a resin having light transmittance. The light-transmitting resin layer 7B may have a total light transmittance of 90 to 100%. The light-transmitting resin layer 7B may have a haze of 0 to 5%.

The difference between the refractive index of the light-transmitting substrate 1 (or the refractive index of the support film constituting the light-transmitting substrate 1) and the refractive index of the light-transmitting resin layer 7B may be 0.1 or less. This makes it easier to ensure good visibility of the displayed image. The refractive index (nd25) of the light-transmitting resin layer 7B may be, for example, 1.0 or more, 1.7 or less, 1.6 or less, or 1.5 or less. The refractive index can be measured by a reflection spectroscopic film thickness meter.

The resin forming the insulating resin portion 7A and the light-transmitting resin layer 7B may be a cured product of a curable resin composition (a photocurable resin composition or a thermosetting resin composition). The curable resin composition forming the insulating resin portion 7A and/or the light-transmitting resin layer 7B includes a curable resin, examples of which include acrylic resin, amino resin, cyanate resin, isocyanate resin, polyimide resin, epoxy resin, oxetane resin, polyester, allyl resin, phenol resin, benzoxazine resin, xylene resin, ketone resin, furan resin, COPNA resin, silicon resin, dicyclopentadiene resin, benzocyclobutene resin, episulfide resin, ene-thiol resin, polyazomethine resin, polyvinylbenzyl ether compound, acenaphthylene, and ultraviolet-curable resins containing functional groups that undergo a polymerization reaction with ultraviolet light, such as unsaturated double bonds, cyclic ethers, and vinyl ethers.

The resin forming the insulating resin part 7A and the resin forming the light-transmitting resin layer 7B may be the same. Since the insulating resin part 7A and the light-transmitting resin layer 7B formed from the same resin have the same refractive index, the uniformity of the optical path length passing through the conductive film 20 can be further improved. When the resin forming the insulating resin part 7A and the resin forming the light-transmitting resin layer 7B are the same, the insulating resin part 7A and the light-transmitting resin layer 7B can be easily formed together, for example, by forming a pattern from a single curable resin layer by an imprinting method or the like.

From the viewpoint of uniformity of the optical path length, the conductor part 3, the insulating resin part 7A, and the light-transmitting resin layer 7B may have substantially the same thickness. For example, when the average value of the thicknesses of the conductor part 3, the insulating resin part 7A, and the light-transmitting resin layer 7B is T, the thicknesses of the conductor part 3, the insulating resin part 7A, and the light-transmitting resin layer 7B may be within ±3 μm, ±2 μm, ±1 μm, ±0.5 μm, or ±0.3 μm of T. The thicknesses of the conductor part 3, the insulating resin part 7A, and the light-transmitting resin layer 7B may be 0.8 μm or more, 1.0 μm or more, or 1.2 μm or more, and may be 5 μm or less, 4 μm or less, or 3 μm or less.

3 is a plan view showing an example of a conductive layer. The conductive layer 5 shown in FIG. 3 has a conductor portion 3, an insulating resin portion 7A, and a power supply terminal 8. The conductor portion 3 has a mesh-like pattern including a plurality of linear portions, and has a wiring portion 31 including a radiating element, a ground electrode 33, and a terminal portion 6. The terminal portion 6 includes two ground terminals 32 and a terminal pattern portion 80 which is a conductor portion 3 extending toward the outside of the wiring portion 31. The ground electrode 33 is provided between the two ground terminals 32 while surrounding the radiating element of the wiring portion 31. The width and shape of the linear portion constituting the ground electrode 33 can be the same as the width and shape of the linear portion constituting the wiring portion 31. The power supply terminal 8 extends in a plane so as to cover a part of the terminal pattern portion 80. The power supply terminal 8 is a conductor layer having a solid form. In a plan view, the outer edge of the power supply terminal 8 may be located inside the outer edge of the terminal pattern portion 80 (conductor portion 3). In this case, the outer edge of the power supply terminal 8 is prevented from protruding beyond the outer edge of the conductor portion 3, thereby preventing the wiring portion 31 from shorting out with another terminal portion adjacent to the terminal portion 6. In addition, it is possible to prevent the power supply terminal 8 from protruding toward the electrode side, thereby preventing the visibility of the conductive film from improving. The terminal pattern portion 80 (conductor portion 3) covered by the power supply terminal 8 may have a mesh-like pattern similar to that of the conductor portion 3 that is not covered by the power supply terminal 8.

Figure 4 is an enlarged cross-sectional view showing a portion of the conductive layer 5 in Figure 3 where the power supply terminal 8 is provided. The power supply terminal 8 shown in Figures 3 and 4 is formed so as to cover the surface of the terminal pattern portion 80 (conductor portion 3) and the surface of the insulating resin portion 7A filling the opening of the terminal pattern portion 80. In the example shown in Figures 3 and 4, the power supply terminal 8 is formed integrally without gaps in the area surrounded by its outer edge. The power supply terminal 8 may be divided into multiple areas, and the terminal pattern portion 80 (conductor portion 3) and the insulating resin portion 7A may be exposed in a slit shape between the divided areas.

As shown in the cross-sectional view of FIG. 4, the height of the terminal pattern portion 80 (conductor portion 3) covered by the power supply terminal 8 from the main surface 1S of the light-transmitting substrate 1 may be greater than the height from the main surface 1S of the insulating resin portion 7A. The surface 8S of the power supply terminal 8 opposite the conductor portion 3 may be roughened. In other words, the surface roughness of the surface 8S may be greater than the surface roughness of the conductor portion 3. If the surface 8S is roughened, the connection strength with an external connection terminal may be improved. The surface roughness here may be, for example, the arithmetic mean roughness Ra. The thickness of the power supply terminal 8 may be greater than the thickness of the conductor portion 3.

The ground terminal may be provided separately from the conductor portion extending on the main surface of the substrate. For example, the ground terminal may be a conductor layer extending in a plane so as to cover the terminal pattern portion as a terminal portion having a pattern including an opening, and having a solid form. In this case, in a planar view, the outer edge of the ground terminal may be located inside the outer edge of the terminal pattern portion (terminal portion, conductor portion) located below it. This prevents the ground terminal from protruding from the outer edge of the conductor portion, thereby preventing the ground terminal from shorting with other adjacent terminal portions. In addition, it is possible to prevent the ground terminal from protruding to the electrode side, thereby improving the visibility of the conductor portion. The terminal pattern portion covered by the ground terminal having a solid form may have a mesh-like pattern similar to the conductor portion of the portion not covered by the ground terminal. The conductive film may have a power supply terminal having a solid form covering the terminal portion (terminal pattern portion), a ground terminal having a solid form covering the terminal portion (terminal pattern portion), or both of these, as described above.

The conductive film 20 can be manufactured by a method including pattern formation by imprinting, for example. One example of a method for manufacturing the conductive film 20 includes preparing a light-transmitting substrate 1 having a support film and a catalyst-containing underlayer provided on one of the main surfaces of the support film, forming a curable resin layer on the main surface 1S of the light-transmitting substrate 1 on the underlayer side, forming a trench in which the underlayer is exposed by an imprinting method using a mold having a convex portion, and forming a conductor portion 3 filling the trench by an electroless plating method in which metal plating is grown from the underlayer. By curing the curable resin layer with the mold pressed into the curable resin layer, an insulating resin portion 7A having a pattern including an opening having an inverted shape of the convex portion of the mold and a light-transmitting resin layer 7B are formed at the same time. The method for forming the insulating resin portion 7A having a pattern including an opening is not limited to the imprinting method, and any method such as photolithography can be applied.

The conductive film described above can be incorporated into a display device as, for example, a planar transparent antenna. The display device may be, for example, a liquid crystal display device or an organic EL display device. FIG. 5 is a cross-sectional view showing an embodiment of a display device incorporating a conductive film. The display device 100 shown in FIG. 5 includes an image display unit 10 having an image display area 10S, a conductive film 20, a polarizing plate 30, and a cover glass 40. The conductive film 20, the polarizing plate 30, and the cover glass 40 are laminated in this order from the image display unit 10 side on the image display area 10S side of the image display unit 10. The configuration of the display device is not limited to the form shown in FIG. 5, and can be appropriately changed as necessary. For example, the polarizing plate 30 may be provided between the image display unit 10 and the conductive film 20. The image display unit 10 may be, for example, a liquid crystal display unit. As the polarizing plate 30 and the cover glass 40, those that are normally used in display devices can be used. The polarizing plate 30 and the cover glass 40 do not necessarily have to be provided. Light for image display emitted from the image display region 10S of the image display unit 10 passes through a path with a highly uniform optical path length that includes the conductive film 20. This makes it possible to display a good image with a high degree of uniformity and with suppressed moire.

1...light-transmitting substrate, 1S...main surface of substrate, 3...conductor portion, 3a...opening, 5...conductive layer, 7A...insulating resin portion, 7B...light-transmitting resin layer, 20...conductive film, 30...polarizing plate, 40...cover glass, 100...display device, SA...first region, SB...second region.

Claims (7)

A film-like light-transmitting substrate;
a conductive layer provided on a first region occupying a part of one main surface of the light-transmitting substrate;
a light-transmitting resin layer provided so as to cover the entire second region including a region other than the first region on one main surface of the light-transmitting base material;
Equipped with
the conductive layer has a conductor portion including a portion having a pattern including an opening extending in an in-plane direction of a main surface of the light-transmitting substrate, and an insulating resin portion filling the opening of the conductor portion,
the conductor portion, the insulating resin portion, and the light-transmitting resin layer have substantially the same thickness;
Conductive film. The conductive film according to claim 1, wherein the area of the first region is smaller than the area of the second region. The conductive film according to claim 1 or 2, wherein the pattern including the openings of the conductor portion is a mesh-like pattern. The conductive film according to any one of claims 1 to 3, wherein the light-transmitting resin layer and the insulating resin portion are cured products of a curable resin composition. The conductive film according to any one of claims 1 to 4, wherein the light-transmitting resin layer and the insulating resin portion are formed from the same resin. The conductive film according to any one of claims 1 to 5 , wherein a difference between a refractive index of the light-transmitting substrate and a refractive index of the light-transmitting resin layer is 0.1 or less. A display device comprising the conductive film according to any one of claims 1 to 6 .

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