JP2011066610A - Transparent antenna - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a transparent antenna with an antenna pattern other than a conventional transparent ITO film, as a conductive layer itself, wherein both sufficient conductivity and transparency are highly achieved when using the conventional ITO film, although the ITO film has had difficulty in achieving them, and to thus achieve application to various uses for a display window of a mobile phone, an automotive window, or the like. <P>SOLUTION: The transparent antenna 10 has the antenna pattern 2 formed on a transparent base 1, and the antenna pattern includes a conductor part 3a as a formation part of an opaque conductor layer and a meshed conductor mesh layer 3 having many openings 3b as non-formation parts. Further, an adhesive layer or the like may be formed on the surface of the transparent base on the opposite side from the antenna pattern formation side or on the surface on the antenna pattern formation side. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a transparent antenna having transparency, and more particularly to a transparent antenna that can achieve both transparency and conductivity of an antenna pattern.

  Currently, as a transparent antenna for receiving various radio waves such as TV radio waves and FM radio waves, or for receiving radio waves of position coordinate information such as GPS (global positioning system) satellites with the spread of car navigation systems, A film antenna attached to a windshield is known. A film antenna is an antenna in which an antenna pattern is usually formed on a transparent polyester film or the like with a metal foil or a conductive paste so as not to obstruct the field of view. However, conductors such as a metal foil and a conductive paste constituting the antenna pattern are opaque per se and do not significantly disturb the field of view, but the antenna pattern itself can be seen. On the other hand, a transparent antenna using an ITO (indium tin oxide) film whose conductor is transparent as an antenna pattern has also been proposed (Patent Documents 1 and 2).

JP-A 63-198401 Japanese Patent Laid-Open No. 02/082701

  However, conventional transparent antennas with opaque conductive patterns such as metal and conductive paste have good conductivity, but the antenna pattern can be seen. It was in the way and was not applicable. In this respect, if an ITO film is used for the antenna pattern, the conductor itself is transparent, so that display is not hindered. However, the ITO film is inferior in conductivity, and the performance as an antenna cannot be sufficiently obtained. Further, the transparency of the ITO film decreases when the conductivity is increased. Therefore, the ITO film as a conductor of a transparent antenna that can be applied to such a use cannot satisfy both sufficient conductivity and sufficient transparency.

  That is, an object of the present invention is to provide a transparent antenna that has both sufficient conductivity and sufficient transparency.

Therefore, the transparent antenna of the present invention is a transparent antenna in which an antenna pattern is formed on a transparent substrate, and the antenna pattern has a large number of openings as a conductive portion and a non-formed portion as an opaque conductor layer forming portion. And a transparent antenna formed by a mesh-like conductor mesh layer.
In the above, an adhesive layer may be further formed on the surface of the transparent substrate opposite to the side on which the antenna pattern is formed or on the side on which the antenna pattern is formed.

  According to the transparent antenna of the present invention, the conductivity is ensured by using a metal layer or a conductive composition layer excellent in conductivity although the conductor itself is opaque. At the same time, the antenna pattern is formed as a mesh-like conductor mesh layer having a large number of openings as the conductor layer, so that both sufficient conductivity and sufficient transparency can be achieved. Furthermore, if an adhesive layer is provided, the attachment to the adherend becomes easy.

Sectional drawing which illustrates one form of the transparent antenna by this invention. The top view which illustrates two forms of the transparent antenna by this invention. Sectional drawing which illustrates another two form (with an adhesive bond layer) of the transparent antenna by this invention. Sectional drawing which illustrates another form (with a transparent protective layer) of the transparent antenna by this invention. Sectional drawing which illustrates another two form (with an antireflection layer) of the transparent antenna by this invention. Sectional drawing which illustrates one form of the conventional transparent antenna.

  Hereinafter, embodiments of the present invention will be described for each layer with reference to the drawings.

[Transparent substrate]
As illustrated in the cross-sectional view of FIG. 1, the transparent substrate 1 is a layer that supports the conductor mesh layer 3 that becomes the antenna pattern 2 and has a function of preventing the deformation and the like.
A known transparent material may be used for the transparent substrate 1, and a resin film (or sheet) is representative in view of transparency in the visible light region, heat resistance, mechanical strength, and the like. The resin of the resin film (or sheet) is, for example, a polyester resin such as polyethylene terephthalate, an acrylic resin such as pomethyl methacrylate, a polycarbonate resin, a polyimide resin, or a polyolefin resin such as a cycloolefin polymer, or triacetyl. Cellulose-based resins such as cellulose. Among these, a biaxially stretched polyethylene terephthalate film is a suitable material. The thickness of the transparent substrate is usually 20 to 500 μm, preferably 25 to 200 μm, in view of handling properties and cost, but is not particularly limited.
In addition, the transparent substrate 1 is preferably a resin film from which a flexible (flexible) material can be selected in terms of easy attachment of the transparent antenna to the adherend. Also, a rigid plate or molded product made of resin or the like can be used. In the case of a plate material, the thickness is usually 0.5 to 10 mm, but is not particularly limited.

[Conductor mesh layer]
As illustrated in the cross-sectional view of FIG. 1, in the present invention, the conductor layer forming the antenna pattern 2 is not formed in the antenna pattern as a solid layer (continuous layer) as in the prior art. However, it is formed by a discontinuous layer called a mesh pattern having a large number of openings 3b. As an expression paying attention to the pattern shape of the discontinuous layer, the conductor layer that becomes the discontinuous layer is defined as a conductor mesh layer. Call. In other words, the conductor mesh layer 3 is a mesh-like conductor layer having a conductor portion 3a as a conductor layer forming portion and a large number of openings 3b as non-forming portions. The conductor mesh layer 3 is formed on at least one side of the transparent substrate 1, but may be on both sides. Moreover, it is good also as a structure which pinches | interposes the conductor mesh layer 3 with the transparent base material 1 from the both surfaces.
The pattern shape of the antenna pattern 2 itself (the contour shape of the conductor mesh layer 3) may be determined according to the application such as a dipole antenna. For example, the plan views of FIGS. 2 (a) and 2 (b) The pattern may be an appropriate pattern shape according to the frequency, electric field strength, gain, application, and the like of radio waves to be transmitted and received.
On the other hand, in the conventional antenna pattern 2 using an ITO film like the conventional transparent antenna 20 illustrated in the cross-sectional view of FIG. 6, the conductor layer is a conductor continuous layer 7 that is a continuous layer throughout the interior of the antenna pattern 2. .

(Mesh shape)
The mesh shape is a mesh pattern whose shape in plan view includes a so-called mesh (lattice or mesh) shape, as well as a stripe shape. The mesh shape is a unit cell, for example, triangles such as regular triangles and isosceles triangles, squares such as squares, rectangles, rhombuses, and trapezoids, polygons such as pentagons, hexagons, and shapes with smooth outlines such as circles and ellipses. The stripe shape is a linear stripe pattern, a spiral pattern, or the like. Among them, a mesh shape in which the unit cell is a square and a square lattice shape is typical. In addition, the shape of the opening is a square in the square lattice shape and a band shape in the stripe shape. The shape of the opening is generally the same shape and the same size on the entire surface, but it may not be uniform on the entire surface, for example, by changing the location.

The conductor portion 3a of the conductor mesh layer 3 is a line in plan view, and the line width is 1 to 100 μm from the viewpoint of conductivity and transparency, and in terms of “invisibility” in which the line pattern is difficult to see. The line width should be as thin as possible, preferably 50 μm or less, more preferably 30 μm or less. Therefore, such a line set to a line width of 50 μm or less, more preferably 30 μm or less, will be referred to as a “thin line”. On the other hand, from the viewpoint of ensuring conductivity and mechanical strength, the line width is 3 μm or more, preferably 10 μm or more. The visibility (easy visibility) of the thin line depends on how far the transparent antenna is visually recognized, so the line width of the thin line is preferably set according to the application. In addition, the line width of the thin line is generally uniform over the entire surface, but it may not be uniform, for example, depending on the location.
Moreover, the period of a thin wire | line is about 50-1000 micrometers. However, it goes without saying that it is within a range that satisfies the required conductivity (surface resistance) in consideration of the aperture ratio to be set. Note that the opening ratio of the conductor mesh layer (defined by (total area of openings that are conductor mesh layer non-formed parts / total covering area of conductor mesh layers including openings) × 100) is conductive and transparent. From the viewpoint of compatibility with the property (visible light transparency), it is preferable to set it to 50% or more, preferably 70% or more.
Moreover, the thickness of the conductor mesh layer is about 1 to 100 μm from the viewpoint of conductivity (and transparency).

(Layer material)
In the present invention, a layer transparent to visible light such as an ITO film is sufficient as a conductor layer that can be used for a conductor mesh layer that can achieve both such conductivity and transparency at a high level. Therefore, it is not adopted because it cannot be expected to have a good conductivity, and a sufficient conductivity can be obtained, but an opaque layer itself is adopted. As the conductor layer that becomes an opaque layer with respect to visible light itself, a known layer may be used as appropriate, and there is no particular limitation as long as it can be formed with a thin line (line width of 50 μm or less). The material and the fine line (mesh pattern) forming method can be appropriately selected from known methods. For example, a metal composition or a conductive composition layer in which conductive particles made of silver or the like are dispersed in a resin binder.

((Metal layer))
The metal of the metal layer is a highly conductive metal, for example, a metal (including alloy) such as gold, silver, copper, platinum, tin, aluminum, iron, or nickel. Among these, copper is generally used as a metal, but it is also preferable to use aluminum which is cheaper than copper.

In the case of a metal layer, the conductor mesh layer can be roughly divided into two methods: a method of forming a pattern from a non-patterned metal layer and a method of forming a patterned metal layer from the beginning.
In the former method, a metal foil laminating method, a plating method, or a dry method such as vapor deposition or sputtering is used to form a non-patterned metal layer. A chemical etching method can be used to form a pattern on the metal layer, and a photolithography method or a printing method is used to form an etching resist pattern. In addition, when a metal layer is formed as a metal thin film by vapor deposition or sputtering, a negative pattern (forming a layer of the resin at the opening portion) is formed in advance with a water-soluble resin on the surface of the metal thin film. There is also a method of removing the metal thin film on the negative pattern together with the water-soluble resin by washing with water after forming the metal thin film.

On the other hand, as a method of forming the metal layer patterned from the beginning of the latter, a method of plating the metal layer only on the catalyst pattern patterned by printing of the plating catalyst ink, conversely, a conductive surface such as metal is used. There is a method of forming a conductive mesh layer by patterning a plating resist on a portion to be an upper non-formed portion and then electroplating the non-formed portion of the plating resist to peel from the conductive surface. In addition, peeling peels with a transparent base material after laminating | stacking a transparent base material further.
In addition, for the metal layer before pattern formation and after pattern formation, a method of changing the laminated surface of the metal layer by using a transfer method can also be used. For example, a conductor mesh layer is laminated on a transparent substrate via an adhesive layer from a transfer foil in which a conductor mesh layer is formed as a transfer layer on a peelable substrate. For the peelable substrate, use a resin film or the like listed on the transparent substrate (but may be opaque), and the adhesive layer is made of acrylic thermoplastic resin or the like on the transfer foil side, the transparent substrate side, or both. Apply.

  In general, the conductor mesh layer is produced by a method of photoetching a metal layer formed by adhesion of metal foil, plating, metal vapor deposition, or the like on a transparent substrate when using a metal layer. In the case of using a conductive composition layer, it is formed by printing an ink made of a conductive composition. The metal layer may be a literal metal mesh formed by knitting (or weaving) a thin metal wire into a mesh shape, but this may be used as long as the antenna pattern can be easily formed.

  In addition, when patterning a plating catalyst pattern, a resist pattern, or a conductive composition layer described below by printing, silk screen printing, flexographic printing, intaglio printing, inkjet printing, etc. may be selected as appropriate. In this case, the “pulling primer type intaglio printing method” described later is particularly preferable because it can be made fine and highly accurate.

In addition, when the metal layer as the conductor mesh layer 3 is an aluminum metal layer, the mesh pattern forming method is not particularly limited, but is preferable in that a fine pattern can be easily formed. It can be performed by etching an aluminum foil. However, the metal aluminum itself is highly active and has an oxide film on the surface. For this reason, it is difficult to perform uniform and stable chemical etching. Giza (the contour line in the plan view of the line portion becomes a ZigZag non-linear shape) etc. Pattern accuracy is poor. However, if the thickness of the oxide film is regulated to 0 to 13 mm or less, uniform and stable chemical etching can be performed, and the conductor mesh layer can be formed of aluminum which is cheaper than copper. The upper limit of the thickness is 13 mm, but is preferably 12 mm, more preferably 10 mm, and still more preferably 8 mm. The lower limit of the thickness is 0 mm from the point of not inhibiting chemical etching, but it is also possible to have an oxide film of about 2 to 3 mm from the viewpoint of preventing undesired oxidation and corrosion during processing and storage of the foil. . Note that 1Å = 0.1 nm.
In addition, the thickness of the oxide film is defined by the side that comes into contact with the etchant first (usually the surface that is far from the transparent substrate because it is etched after laminating the foil on the transparent substrate; The other surface (lower surface) can be defined in the same manner. In addition, the oxide film of a general aluminum foil has a thickness of 15 mm or more, usually about 20 to 100 mm.
Moreover, in order to reduce the thickness of the oxide film, it is possible to adjust rolling conditions and annealing conditions at the time of manufacturing the aluminum foil. The thickness of the oxide film is measured by the Hunter Hall method or X-ray photoelectron spectroscopy (XPS) which is a kind of fluorescent X-ray analysis.
In addition, the aluminum foil preferably has a purity of 99.0% or more from the viewpoint of high conductivity, and is a foil conforming to the aluminum foil defined by JIS H4160 (aluminum and aluminum alloy foil) and JIS H4170 (high purity aluminum foil). Can be used.

(Conductive composition layer)
The conductive composition layer as the conductor mesh layer 3 is a layer in which conductive particles are dispersed in a resin binder. Examples of the conductive particles include gold, silver, platinum, copper, tin, aluminum, and nickel. Conductive metal (including alloy) particles may be used, or metal-coated particles in which the surfaces of resin particles or inorganic particles are coated with the above highly conductive metal such as gold or silver, or graphite particles may be used.

  In addition, as the resin of the resin binder, a thermoplastic resin, a thermosetting resin, an ionizing radiation curable resin, or the like is used alone or in combination. A thermoplastic polyester resin, a thermoplastic acrylic resin, or the like is used as the thermoplastic resin, and a melamine resin, a thermosetting polyester resin, a thermosetting acrylic resin, a thermosetting urethane resin, or the like is used as the thermosetting resin. In addition, as the ionizing radiation curable resin, a composition containing a monomer and / or a prepolymer that undergoes a crosslinking reaction with ionizing radiation and is cured. As the monomer or prepolymer, a radical polymerizable or cationic polymerizable compound is used. Among these, ionizing radiation curable resins using acrylate compounds are typical.

The conductive composition layer can be patterned from the beginning at the time of layer formation. When patterning by printing, silk screen printing, flexographic printing, intaglio printing, ink jet printing, etc. may be appropriately selected. The “pulling primer intaglio printing method” described later is preferable in that a fine pattern can be formed with high accuracy. The conductive composition is also called conductive ink, conductive paste, or the like.
In addition, after forming a pattern groove of a desired pattern on the surface of the transparent substrate and applying the conductive composition to the entire surface of the substrate, an unnecessary conductive composition other than the groove The conductive mesh layer can also be formed by scraping off an object with a blade or the like and leaving the conductive composition only in the groove (so-called wiping method). The substrate for forming the pattern groove may be a transparent substrate, or may be laminated on the transparent substrate by transfer after being formed on another substrate.

(("Pulling Primer Intaglio Printing Method for Conductive Composition Layer")))
This printing method is a printing method disclosed by the present applicant in International Publication No. WO2008 / 149969, and can be referred to as a “transition promoting layer”. The ink filled in the concave portion of the intaglio plate surface is drawn out, and the ink on the printing material is extracted. This is an intaglio printing method characterized in that a layer called a “primer layer” that promotes transfer is allowed to act in a fluid state during printing. Therefore, here, this intaglio printing method is referred to as “pulling primer type intaglio printing method”.

  In the drawing primer type intaglio printing method, for example, printing is performed as follows. A conductive composition such as a conductive paste before solidification is filled only in the concave portion of the intaglio plate surface with a doctor blade, and the conductive composition on the convex portion of the plate surface other than the concave portion is scraped off and removed. The surface of the conductive composition filled in the recesses is not completely flush with the plate surface (convex portions), and a slightly depressed recess is generated. When a transparent base material coated with a fluidized primer fluidized bed is supplied to the intaglio plate and the primer fluidized bed is pressure-bonded to the plate surface, the primer fluidized bed flows into the recess and fills the recess, cover. In this state, the primer fluidized layer is solidified by ultraviolet curing or the like to form a primer layer, and then the transparent substrate is released from the intaglio, and the primer layer solidified on the transparent substrate and an uncured conductive composition, Or the printed matter by which the conductor layer which consists of a conductive composition layer by which the conductive composition was hardened was laminated | stacked. The solidification of the conductor layer is performed after the release when the uncured conductive composition contains a solvent, and after the release in the case of no solvent, or simultaneously with the primer solidification before the release or after the primer solidification. Do.

  And, such a printed matter by the “pulling primer intaglio printing method” is a major feature that is not seen in other printing methods, the interface between the primer layer and the conductive composition layer, the primer layer is the conductive composition The thickness of the convex portion which is the conductor portion 3a of the layer forming portion is thicker than the thickness of the opening portion 3b which is a non-forming portion of the conductive composition layer.

  Furthermore, the interface between the primer layer and the conductive composition layer has one or more of the following cross-sectional forms (A) to (C). (A) Cross-sectional form in which the interface between the primer layer and the conductive composition layer is in a non-linear manner, and (B) the component constituting the primer layer and the component constituting the conductive composition layer are mixed. A cross-sectional form having a mixed region in the vicinity of the interface, and (C) a cross-sectional form in which a component contained in the primer layer is present in the conductive composition constituting the conductive composition layer. Such a cross-sectional form of the interface is such that the primer layer reinforces the adhesiveness at the time of release between the primer layer and the conductive composition layer, and the printing material (transparent substrate) from the intaglio to the ink (conductive composition) This is considered to be the reason why the transition to JIS is promoted, and high-precision and high-quality intaglio printing is possible.

In addition, inside the convex part of the conductor part 3a, which is the formation part of the conductive composition layer, the conductive particles are not uniformly distributed, but the distribution of the conductive particles is relatively the top of the convex part. An internal structure with a distribution that is dense near and sparse near the primer layer farther from the top is preferred. Density is the number density in terms of the number of conductive particles in a unit volume. That is, the number density of the conductive particles inside the convex portion is a distribution that is larger near the top than in the vicinity of the primer layer. The larger the number density, the easier the electrical contact between the conductive particles. Therefore, even if the average concentration of the conductive particles in the conductive composition is the same, the electric number in the portion where the number density is larger than that in the case where the same number of conductive particles are uniformly distributed. The decrease in resistance contributes to a decrease in electrical resistance as a whole, and the conductive performance is improved. Furthermore, since the number density of the conductive particles in the vicinity of the boundary with the primer layer is small, the adhesion between the conductive composition layer and the primer layer is improved.
Thus, in order to make the conductive particles unevenly distributed toward the top of the convex portion, for example, the pressure-bonding force is increased in the step of pressure-bonding the transparent substrate on which the primer fluidized layer is formed to the plate surface, and the conductive composition is It is preferable to lower the viscosity and solidify after releasing from the plate surface without solidifying in the intaglio recess. In addition, it depends on the viscosity of the conductive composition before solidification (resin material and resin amount, solvent amount, amount of other additives, shape of conductive particles, particle size distribution, content, etc.), solidification conditions, etc. These may be determined experimentally as appropriate.

  For the primer layer, a thermoplastic resin, a curable resin, or the like is used. As the curable resin, a thermosetting resin or an ionizing radiation curable resin can be used, but a rapid change from a fluidized state to a solidified state is possible. Preferably, ionizing radiation curable resin is used in that it can be controlled. As the ionizing radiation, ultraviolet rays, electron beams and the like can be used.

(Blackening treatment)
The conductive mesh layer 3 formed as a metal layer, a conductive composition layer, or the like exhibits a bright color such as a metal color or silver color, and this makes the fine lines of the mesh pattern stand out, so that it does not stand out. In addition, the surface may have a blackening treatment layer. As the blackening treatment layer, in the case of a metal layer, a known treatment such as blackening nickel plating may be appropriately employed. Alternatively, in the case of the conductive composition, a black or dark color material such as carbon black may be added to the composition.

(Method of making conductor mesh layer into antenna pattern shape)
In order to form the pattern shape of the antenna pattern 2 with the conductor mesh layer 3 having the mesh pattern as described above, it may be performed simultaneously with the formation of the mesh pattern of the conductor mesh layer. That is, the mesh pattern of the conductor mesh layer may be formed using the contour shape of the region of the conductor mesh layer 3 (mesh pattern) as the pattern shape of the antenna pattern.
Alternatively, the conductor mesh layer 3 may be formed in a pattern shape of the antenna pattern from one (general raw material) formed in a wider area than the antenna pattern. For example, by forming a conductive mesh layer 3 on a transparent base material as a general-purpose raw material, this is formed by cutting or cutting the whole transparent base material into an antenna pattern shape according to the required antenna pattern shape it can. Moreover, when a conductor mesh layer is a metal layer, it can form by removing the conductor mesh layer of the unnecessary area | region of this general purpose raw material by an etching.
Thus, the method for making the conductor mesh layer into the antenna pattern shape is not particularly limited.

(Other)
In the present invention, the antenna pattern 2 is formed of the conductor mesh layer 3, but a conductor layer other than the conductor mesh layer may exist as the conductor layer included in the transparent antenna. What is necessary is just to employ | adopt a well-known conductor for this conductor layer suitably.
Further, the transparency of the transparent antenna itself (within the antenna pattern region) is visible light transmittance of 50% or more, more preferably 70% or more in the visible light wavelength region of 380 to 780 nm. .

[Adhesive layer]
Like the transparent antenna 10 illustrated in the cross-sectional views of FIGS. 3A and 3B, the adhesive layer 4 has a surface opposite to the side on which the antenna pattern 2 of the transparent substrate 1 is formed {FIG. 3 (a)} or the surface {FIG. 3 (b)} on the side where the antenna pattern 2 is formed. Alternatively, it may be formed on both of these surfaces (not shown). Adhesion to the adherend is facilitated by the adhesive layer. In addition, although this adhesive bond layer is transparent, what is necessary is just to select a well-known transparent thing suitably. As the adhesive, various forms are used. For example, (1) a so-called heat seal (hot seal) type or hot melt (hot melt) type adhesive that uses a thermoplastic resin and is cooled and solidified after heat melting and bonded, and (2) a thermosetting resin. Use, so-called thermosetting adhesive, which is cured by a polymerization or cross-linking reaction by heating, and (3) an ionizing radiation curable resin, and is cured by an ionizing radiation irradiation or cured by a cross-linking reaction to be bonded. A so-called ionizing radiation curable adhesive, (4) using a resin having adhesiveness on the surface, and adhering only by contact and pressurization (without using energy such as heating, ionizing radiation irradiation, or chemical reaction); Examples include so-called pressure-sensitive adhesives. Among these, a pressure-sensitive adhesive is general-purpose and convenient in that a special treatment such as heating is unnecessary and re-peeling is possible as necessary.
Examples of the adhesive layer using the adhesive as the adhesive, that is, the adhesive layer, are, for example, an acrylic adhesive, a silicone adhesive, a rubber adhesive, and the like, and a known coating method or an adhesive film with a separator, etc. It is formed by laminating.
Moreover, the separator (release paper) which peels at the time of use is normally laminated | stacked on the adhesive surface of an adhesive layer. As a separator, a well-known thing may be sufficient, and since it peels and removes at the time of use other than a transparent thing, it does not need to be transparent. Examples of such a separator include a polyester film or paper coated with a peelable material such as silicone.
Moreover, as these various adhesive layers, in addition to the form consisting of only the adhesive layer, a core material sheet such as a nonwoven fabric or a resin sheet is provided as an intermediate layer, and an adhesive layer is laminated on both front and back surfaces. (So-called double-sided adhesive tape) can also be used.

[Transparent protective layer]
Further, like the transparent antenna 10 illustrated in the cross-sectional view of FIG. 4, a transparent protective layer 5 may be formed on the antenna pattern 2 to protect the antenna pattern from external force. The transparent protective layer 5 is formed on at least the antenna pattern 2, but may be formed on the entire surface of the transparent antenna including the portion where the antenna pattern 2 is not formed. The transparent protective layer 5 can be formed by laminating a transparent resin film via an adhesive or pressure-sensitive adhesive or applying a transparent resin paint.
In addition, what was listed by the said transparent base material etc. can be used for a transparent resin film, A well-known thing, such as a urethane resin type, is used for an adhesive, and what is known, such as what was listed by the said adhesive layer, is used for an adhesive. Can be used.
Further, as the resin of the transparent resin paint, a thermoplastic resin, a curable resin, and the like can be used, and the thermoplastic resin is, for example, an acrylic resin, a polyester resin, a cellulose resin, a thermoplastic urethane resin, The curable resin is, for example, a thermosetting resin such as a thermosetting urethane resin, a thermosetting acrylic resin, or an epoxy resin, or an ionizing radiation curable resin that is cured by ultraviolet rays or an electron beam. Examples of the ionizing radiation curable resin include resins containing a radical polymerizable compound typified by an acrylate type and a cationic polymerizable compound typified by an epoxy type.

[Antireflection layer]
Further, like the transparent antenna 10 illustrated in the cross-sectional views of FIGS. 5A and 5B, the antireflection layer 6 is provided on the surface on the side where the antenna pattern 2 of the transparent substrate 1 is formed {FIG. a)} or a surface {FIG. 5 (b)} opposite to the side on which the antenna pattern 2 is formed. By providing the antireflection layer 6, it is possible to prevent a decrease in light transmittance due to surface reflection and to prevent a decrease in transparency of the entire transparent antenna.
Any known antireflection layer 6 may be used as appropriate. For example, in the antireflection layer, a low refractive index layer and a high refractive index layer are alternately laminated so that the low refractive index layer is located on the outermost surface. In other words, each layer is formed by a wet method such as coating, or a dry method such as vapor deposition or sputtering. For example, the low refractive index layer uses silicon oxide, magnesium fluoride, lithium fluoride, calcium fluoride, fluorine-containing resin, etc. as the low refractive index material, and the high refractive index layer uses oxidized material as the high refractive index material. Titanium, zirconium oxide, niobium oxide, etc. are used. When the coating is formed, a curable resin such as a thermosetting resin or an ionizing radiation curable resin as listed in the transparent protective layer is preferably used as the binder resin. For example, a resin layer in which hollow silica is dispersed in an ionizing radiation curable resin as a low refractive index material is used for the low refractive index layer, and zirconium oxide is used as a high refractive index material in the ionizing radiation curable resin for the high refractive index layer. The resin layer dispersed in is used, or a transparent substrate or the transparent protective layer itself is substituted.

[Usage]
The transparent antenna according to the present invention can be used for various applications. For example, in applications to be attached to the window of a vehicle such as an automobile, mobile information devices such as a car navigation system, such as a TV, radio, GPS (Global Positioning System) satellite, and other radio wave receiving antennas, transmission or transmission / reception antennas, and cellular phones. For reception, transmission, transmission / reception antennas attached to display windows, etc., for transmission, reception, transmission / reception antennas, transparent windows for product display cases, etc. A signal transmission / reception antenna or the like for inventory management using an attached IC tag.

  Next, the present invention will be described in further detail with reference to examples.

[Example 1]
On one side of a transparent substrate made of a biaxially stretched transparent polyethylene terephthalate film, a conductive mesh layer is formed as a conductive composition layer by a “drawing primer type intaglio printing method” with a predetermined antenna pattern. Created. An ultraviolet curable acrylic resin was used for the primer layer, and the conductive composition layer was formed of a silver paste in which scaly silver particles were dispersed as a conductive particle in a resin binder containing a thermoplastic polyester urethane resin and a solvent. The conductor mesh layer has a thickness of 20 μm, a mesh line width of 20 μm, and a square lattice serving as openings arranged in a repeating pitch of 300 μm, and the thickness is 19 μm. The aperture ratio is (280 × 280) ÷ (300 × 300) × 100 = 87%.
Further, the antenna pattern is a half-wave dipole antenna for transmission / reception in the 2.45 GHz band, and has a form as shown in FIG. 2B, which is composed of two rectangular pieces having a length of 30 mm and a width of 40 mm. As a result of measuring the radiation characteristics, the same antenna characteristics as those of the present example were obtained, which are the same as those of the current metal dipole antenna in which the antenna pattern is made of a copper foil having a thickness of a continuous film of 20 μm.

DESCRIPTION OF SYMBOLS 1 Transparent base material 2 Antenna pattern 3 Conductor mesh layer 3a Conductor part 3b Opening part 4 Adhesive layer 5 Transparent protective layer 6 Antireflection layer 7 Conductor continuous layer 10 Transparent antenna 20 Conventional transparent antenna

Claims (2)

In a transparent antenna in which an antenna pattern is formed on a transparent substrate,
A transparent antenna in which an antenna pattern is formed by a conductor mesh layer in the form of a mesh having a conductor portion as an opaque conductor layer forming portion and a large number of openings as non-forming portions. The transparent antenna according to claim 1, wherein an adhesive layer is further formed on the surface of the transparent substrate opposite to the side on which the antenna pattern is formed or on the side on which the antenna pattern is formed.

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