Antenna, display device and display system

Abstract

To provide an antenna capable of efficiently receiving electric waves without affecting perceptibility of an object in which the antenna is installed, and to provide a display device and a display system.SOLUTION: In an electronic shelf label 10 of a merchandise display shelf in a display system, an antenna 13 is a light permeable antenna which is formed from a conductor at least including a metal nanowire and receives an electric wave for power feeding (an electric energy transmitted by an electromagnetic wave) transmitted from an external terminal for power feeding. The antenna 13 exerts no influence on perceptibility of the display unit 11 since the antenna 13 has light permeability. In addition, an installation space for the antenna can be sufficiently secured even in the electronic shelf label 10 used for a long, narrow space of the merchandise display shelf since the antenna 13 is provided on a display surface 11a of the display unit 11.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an antenna, a display device, and a display system. [Background technology]

[0002] In recent years, microwave wireless power supply technology has been attracting attention. It has been proposed to apply this wireless power supply technology to supply power to electronic devices equipped with a display unit (hereinafter also referred to as "display device"). For example, a system has been proposed that supplies power wirelessly to electronic shelf tags placed on product shelves in retail stores (see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-97923 Summary of the Invention [Problem to be solved by the invention]

[0004] When power is supplied wirelessly, it is desirable to secure as much space as possible for installing an antenna on the display device. However, for display devices used in the narrow spaces of product display shelves, such as electronic shelf labels, it is difficult to secure sufficient space for installing the antenna, making it difficult for the antenna to receive radio waves efficiently.

[0005] On the other hand, as an alternative to securing antenna installation space, it is possible to install an antenna made of a mesh-like metal film or a transparent conductive film such as ITO on the display unit. However, both of these are expected to have issues such as low transparency and the occurrence of moire. For this reason, there is a need for a system that can receive radio waves more efficiently without affecting the visibility of the object (display unit) on which it is installed.

[0006] An object of the present invention is to provide an antenna, a display device, and a display system that can receive radio waves more efficiently without affecting the visibility of the object on which they are installed. [Means for solving the problem]

[0007] The present invention solves the problems by the following means. For ease of understanding, the following description will be given with reference numerals corresponding to the embodiments of the present invention, but the present invention is not limited to these. Furthermore, the configurations described with reference numerals may be modified as appropriate, and at least a portion of the configurations may be replaced with other components.

[0008] The first invention relates to an optically transparent antenna (13) formed of a conductor (33) including at least metal nanowires, for receiving electrical energy transmitted by electromagnetic waves.

[0009] A second invention is the antenna according to the first invention, wherein the metal nanowire is a silver nanowire.

[0010] A third invention is the antenna according to the second invention, wherein the conductor containing the silver nanowires has a total light transmittance of 70% or more and a haze value of 10% or less.

[0011] The fourth invention relates to a display device (10) comprising a display unit (11) that displays appeal information and an antenna according to any one of the first to third inventions that is provided on the display surface (11a) of the display unit, wherein the antenna receives power supply radio waves as the electrical energy and supplies power to the display unit based on the received power supply radio waves.

[0012] A fifth aspect of the present invention is the display device according to the fourth aspect of the present invention, wherein the panel of the display unit is electronic paper.

[0013] The sixth invention is a display device according to the fourth or fifth invention, which is provided with a display control unit (17) that controls the display of the display unit, and the antenna or an antenna (15) separate from the antenna receives display radio waves as the electrical energy, and the display control unit displays appeal information on the display unit based on the received display radio waves.

[0014] A seventh aspect of the present invention relates to a display system (1) including a display device according to any one of the fourth to sixth aspects of the present invention, and an external terminal (21, 22) that transmits the electric energy to the display device. [Effects of the Invention]

[0015] According to the present invention, it is possible to provide an antenna, a display device, and a display system that can receive radio waves more efficiently without affecting the visibility of the object on which they are installed. [Brief explanation of the drawings]

[0016] [Figure 1] 1A and 1B are diagrams illustrating a usage mode of a display system 1 according to an embodiment. [Figure 2] FIG. 2 is a plan view of the electronic shelf label 10. [Figure 3] FIG. 2 is a cross-sectional view of the display unit 11. [Figure 4] 3A to 3C are schematic diagrams showing the manufacturing process of the transparent conductive sheet 113. [Figure 5] 3A to 3C are schematic diagrams showing the manufacturing process of the transparent conductive sheet 113. [Figure 6] 3A to 3C are schematic diagrams showing the manufacturing process of the transparent conductive sheet 113. [Figure 7] 10 is a sequence diagram showing a procedure for controlling rewriting of appeal information displayed on the electronic shelf label 10. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0017] Hereinafter, embodiments of an antenna, a display device, and a display system according to the present invention will be described. The drawings attached to this specification are all schematic diagrams, and the shape, scale, aspect ratio, etc. of each part have been modified or exaggerated from the actual product for ease of understanding. Furthermore, hatching indicating cross sections of components has been omitted as appropriate in the drawings.

[0018] In this specification, the state in which the electronic shelf label 10 as a display device is installed on a product display shelf 100 as shown in Figure 1 is taken as a reference, and the width direction or left-right direction of the electronic shelf label 10 is taken as the X direction, the height direction or up-down direction is taken as the Y direction, and the thickness direction orthogonal to the XY directions is taken as the Z (Z1-Z2) direction.

[0019] Fig. 1 is a diagram illustrating a usage mode of a display system 1 according to this embodiment. Fig. 2 is a plan view of an electronic shelf label 10. Fig. 3 is a cross-sectional view of a display unit 11. As shown in FIG. 1, an electronic shelf label (display device) 10 is installed on a product display shelf 100 in a retail store, supermarket, or the like. Information such as the names and prices of products placed on each shelf of the product display shelf 100 is displayed collectively on the electronic shelf label 10. Two external terminals are installed on the ceiling surface of the store where the product display shelf 100 is installed. The power supply external terminal 21 is an external terminal that transmits power supply radio waves as electrical energy to the electronic shelf label 10. The display external terminal 22 is an external terminal that transmits display radio waves as electrical energy to the electronic shelf label 10. Note that, in this embodiment, a system is described in which the power supply radio waves and the display radio waves are transmitted from dedicated external terminals, but a system in which the power supply radio waves and the display radio waves are transmitted from a single external terminal may also be used. In FIG. 1, the electronic shelf label 10, the power supply external terminal 21, and the display external terminal 22 constitute a display system 1 of this embodiment.

[0020] As shown in FIG. 2, the electronic shelf label 10 includes a display unit 11, a drive unit 12, a first antenna 13, a first conversion unit 14, a second antenna 15, a second conversion unit 16, and a control unit (display control unit) 17. The above-mentioned components constituting the electronic shelf label 10 are arranged on a base substrate (not shown) and housed in a case 18 that is elongated in the width direction X.

[0021] The display unit 11 is a device that displays information such as the product name and price (hereinafter also referred to as "appeal information"). For example, electronic paper can be used as the panel of the display unit 11. For example, an electrophoretic method can be adopted as a display method for electronic paper suitable for the panel of the display unit 11. The electrophoretic method is a display method that displays information by utilizing an electrophoretic phenomenon that occurs when a voltage is applied to colored particles dispersed in a liquid. Electrophoretic electronic paper has display retention properties that allow the display content to be rewritten by applying a voltage and then retain the display content even after the voltage application is stopped. Examples of electrophoretic methods suitable for electronic paper that serves as the panel of the display unit 11 include a microcapsule electrophoresis method, a microcup electrophoresis method, and an in-plane method. The display surface 11a of the display unit 11 is exposed through an opening 18a formed in the case 18. As described below, a first antenna 13 is provided on the display surface 11a of the display unit 11 exposed through the opening 18a.

[0022] The driving unit 12 is a driver circuit that outputs a driving signal corresponding to the appeal information to the display unit 11. The driving unit 12 generates a driving signal corresponding to the data signal of the appeal information based on power supplied from a first conversion unit 14 (described later), and outputs the driving signal to the display unit 11. The operation of the driving unit 12 is controlled by a control unit 17 (described later).

[0023] The first antenna 13 is an optically transparent antenna that receives power supply radio waves (electrical energy transmitted by electromagnetic waves) transmitted from the power supply external terminal 21. The first antenna 13 is an antenna that receives power supply radio waves with a center frequency of 920 MHz. For example, a patch antenna can be used as the first antenna 13. The power supply radio waves are radio waves that become power for driving the display unit 11. The first antenna 13 is provided on the display surface 11a of the display unit 11. In this way, in this embodiment, the display unit 11 is the object on which the first antenna 13 is installed. The configuration of the first antenna 13 will be described later.

[0024] The first conversion unit 14 is a circuit that converts the power supply radio waves received by the first antenna 13 into power (hereinafter also referred to as "power supply power") for driving the display unit 11. The power supply power converted in the first conversion unit 14 is supplied to the drive unit 12.

[0025] The second antenna 15 is an antenna that receives display radio waves (electrical energy transmitted by electromagnetic waves) transmitted from the display external terminal 22. The second antenna 15 is an antenna separate from the first antenna 13. The second antenna 15 is an antenna that receives display radio waves having a center frequency of, for example, 2.4 GHz. For example, a dipole antenna can be used as the second antenna 15. The display radio waves are radio waves modulated by appeal information (data signals) to be displayed on the display unit 11. The second antenna 15 is provided near the display unit 11 on the aforementioned substrate (not shown).

[0026] The second conversion unit 16 is a circuit that acquires a data signal of the appeal information from the display radio wave by demodulating the display radio wave received by the second antenna 15. The data signal of the appeal information acquired by the second conversion unit 16 is output to the control unit 17.

[0027] The control unit 17 is a control unit that controls the operation of the electronic shelf label 10. The control unit 17 is configured with a microprocessor including a CPU (Central Processing Unit), memory, etc. In order to display the data signal of the appeal information converted by the second conversion unit 16 on the display unit 11, the control unit 17 transmits the data signal of the appeal information to the drive unit 12 and controls the operation of the drive unit 12. As described above, the drive unit 12 generates a drive signal corresponding to the data signal of the appeal information based on the power supply power supplied from the first conversion unit 14, and outputs the drive signal to the display unit 11.

[0028] Next, the layer structure of the first antenna 13 will be described with reference to Fig. 3. Fig. 3 shows (a part of) the first antenna 13 after being patterned into the shape of the antenna. Note that the layer structure of the first antenna 13 shown in Fig. 3 is one example, and is not limited to the example shown in Fig. 3. Also, Fig. 3 shows the thickness of each layer schematically, and differs from the actual thickness.

[0029] As shown in FIG. 3, the first antenna 13 includes a light-transmitting substrate 31, a hard coat layer 32, a conductive layer 33, and an overcoat layer . The light-transmitting substrate 31 is a film that supports the hard coat layer 32 and the conductive layer 33. Examples of resins that can be used for the light-transmitting substrate 31 include polyethylene terephthalate (PET) and cycloolefin polymer (COP). When using cycloolefin polymer as the light-transmitting substrate 31, it is preferable to provide a hard coat layer (not shown) between the light-transmitting substrate 31 and the conductive layer 33 to improve durability. When the first antenna 13 is manufactured by a transfer method, the light-transmitting substrate 31 may not remain. For example, in the configuration shown in FIG. 3, a film in which the positions of the light-transmitting substrate 31 and the hard coat layer 32 are reversed may be used, and the conductive layer 33 may be transferred to the front side Z1 of the display unit 11, and then the light-transmitting substrate 31 may be peeled off. The thickness of the first antenna 13 is, for example, approximately 0.1 to 300 μm.

[0030] The hard coat layer 32 is a resin layer provided on the front side Z1 of the light-transmitting substrate 31. The hard coat layer 32 is a layer that is light-transmitting and harder than the light-transmitting substrate 31. Examples of resins that constitute the hard coat layer 32 include those containing a polymer (cured product, cross-linked product) of a polymerizable compound. The resin may contain a solvent-drying resin in addition to a polymer of a polymerizable compound. Examples of polymerizable compounds include ionizing radiation-polymerizable compounds and / or thermally polymerizable compounds. Among these, ionizing radiation-polymerizable compounds are preferred as the polymerizable compound because of their fast curing rate and ease of design. Note that an anti-glare layer may be formed instead of the hard coat layer 32. Depending on the layer configuration of the first antenna 13, the hard coat layer 32 may be omitted.

[0031] The conductive layer 33 is a layer (conductor) having electrical conductivity. The conductive layer 33 includes conductive fibers 35 and a light-transmitting resin (resin portion) 36. Note that the conductive layer 33 does not necessarily include the light-transmitting resin 36 as long as it includes the conductive fibers 35. The conductive fibers 35 are disposed in the light-transmitting resin 36. In this specification, a "conductive fiber" is defined as a fiber that is electrically conductive and has a shape whose length is sufficiently longer than its thickness (for example, its diameter). For example, a fiber whose length is approximately five times or more its thickness is considered to be a conductive fiber.

[0032] In the conductive layer 33, it is preferable that the conductive fibers 35 contact each other to form a network structure (mesh structure) in the planar direction (two-dimensional direction) of the conductive layer 33. When the conductive fibers 35 form a network structure, a conductive path can be formed in the planar direction.

[0033] The surface resistivity (Ω / □) of the conductive layer 33 can be adjusted by the amount of conductive fibers 35 arranged in the conductive layer 33. If the fiber diameter, fiber length, material, etc. of the conductive fibers 35 are the same, the surface resistivity can be increased by decreasing the amount of conductive fibers 35. Furthermore, the surface resistivity can be decreased by increasing the amount of conductive fibers 35. From the viewpoint of ensuring a total light transmittance of 70% or more, it is desirable to set the surface resistivity (Ω / □) of the conductive layer 33 to approximately 0.1 to 100 Ω / □. Furthermore, from the viewpoint of ensuring a coloring (hue) of the appearance and high transparency, it is more desirable to set the surface resistivity of the conductive layer 33 to any of the following ranges: 3 to 50, 3 to 30, 5 to 50, 5 to 30, 10 to 50, 10 to 30, 15 to 50, or 15 to 30 (Ω / □).

[0034] The total light transmittance (%) of the conductive layer 33 can be measured, for example, in an environment of 23±5°C temperature and 30% to 70% relative humidity using a haze meter (product name "HM-150" manufactured by Murakami Color Research Laboratory) in accordance with JIS K 7361-1 (1997). The surface resistivity (Ω / □) of the conductive layer 33 can be measured, for example, in an environment of 23±5°C temperature and 30% to 70% relative humidity using a contact resistivity meter (product name "Loresta AX MCP-T370" manufactured by Mitsubishi Chemical Analytech Co., Ltd., terminal shape: ASP probe) and a non-destructive (eddy current) resistivity meter (product name "EC-80P" manufactured by Napson Corporation) in accordance with JIS K 7194:1994 (resistivity test method for conductive plastics using the four-probe method).

[0035] The fiber diameter of the conductive fiber 35 is preferably 100 nm or less. If the fiber diameter of the conductive fiber 35 is 100 nm or less, an increase in the haze value of the first antenna 13 can be suppressed and there is no risk of a decrease in light transmittance. The lower limit of the fiber diameter of the conductive fiber 35 is preferably 3 nm or more or 5 nm or more so that the shape can be stably maintained and the conductivity of the conductive layer 33 can be ensured. The upper limit of the fiber diameter of the conductive fiber 35 is more preferably 50 nm or less or 30 nm or less from the viewpoint of ensuring a total light transmittance of 70% or more and a haze value of 10% or less. More preferred ranges of the fiber diameter of the conductive fiber 35 are 1 nm or more to 15 nm or less, or 1 nm or more to 10 nm or less, etc. The haze value (%) of the conductive layer 33 can be measured, for example, in an environment of a temperature of 23±5°C and a relative humidity of 30% or more and 70% or less, in accordance with JIS K 7136:2000 using a haze meter (product name "HM-150", manufactured by Murakami Color Research Laboratory).

[0036] The fiber length of the conductive fibers 35 is preferably 1 μm or more. If the fiber length of the conductive fibers 35 is 1 μm or more, a conductive layer 33 having sufficient conductive performance can be formed, and the occurrence of aggregation can be suppressed, so there is no risk of an increase in haze value or a decrease in light transmittance. The upper limit of the fiber length of the conductive fibers 35 may be 100 μm or less, 30 μm or less, or 20 μm or less. The lower limit of the fiber length of the conductive fibers 35 may be 3 μm or more, 5 μm or more, or 10 μm or more.

[0037] Metal fibers are preferably used as the conductive fibers 35. Metal nanowires made of, for example, stainless steel, Ag, Cu, Au, Al, Rh, Ir, Co, Zn, Ni, In, Fe, Pd, Pt, Sn, Ti, or alloys thereof are preferred. Among metal nanowires, silver nanowires are particularly preferred due to their high electrical and thermal conductivity. When silver nanowires are used as the conductive fibers 35, a total light transmittance of 80% or more can be achieved by setting the surface resistivity of the first antenna 13 to 5 Ω / □ or higher. Furthermore, a total light transmittance of approximately 90% can be achieved by setting the surface resistivity of the first antenna 13 to 30 Ω / □. For example, fibers produced by a wire drawing method or a cutting method, which stretches the above metals thin and long, can be used as the metal fibers. One or more types of such metal fibers can be used.

[0038] When silver nanowires are used as the metal fibers, they can be synthesized by liquid-phase reduction of a silver salt (e.g., silver nitrate) in the presence of a polyol (e.g., ethylene glycol) and poly(vinylpyrrolidone). Mass production of uniformly sized silver nanowires can be achieved, for example, by the methods described in Xia, Y. et al., Chem. Mater. (2002), 14, 4736-4745 and Xia, Y. et al., Nanoletters (2003), 3(7), 955-960.

[0039] There is no particular limitation on the means for producing metal nanowires, and known means such as a liquid phase method or a gas phase method can be used. There is also no particular limitation on the specific production method, and known production methods can be used. For example, as a method for producing silver nanowires, reference can be made to Adv. Mater., 2002, 14, 833-837; Chem. Mater., 2002, 14, 4736-4745, etc.

[0040] The light-transmitting resin 36 covers the conductive fibers 35 to prevent the conductive fibers 35 from falling off from the conductive layer 33 and to improve the durability and abrasion resistance of the conductive layer 33. The light-transmitting resin 36 is not particularly limited as long as it is a resin that has light transparency, and examples of the light-transmitting resin include a polymer of a polymerizable compound and a plastic resin.

[0041] The overcoat layer 34 is a resin layer for protecting the conductive layer 33, and is provided on the back side Z2 of the conductive layer 33. There are no particular restrictions on the overcoat agent used for the overcoat layer, and a general overcoat agent can be used. Note that depending on the layer configuration of the first antenna 13, the overcoat layer 34 may be omitted.

[0042] As will be described later, the first antenna 13 is patterned by laser etching, punching, or the like, and then attached to the display surface 11a of the display unit 11 via an adhesive layer or a bonding layer (not shown). The first antenna 13 can be attached directly to the display surface 11a of the display unit 11, but it may also be configured such that, for example, a protective base material is attached to the front side Z1 of the first antenna 13, and the first antenna 13 is attached via this base material.

[0043] Next, a method for manufacturing the first antenna 13 will be described. In the following description, the sheet-like first antenna 13 before being patterned into the shape of an antenna will be referred to as the "transparent conductive sheet 113." The method for manufacturing the transparent conductive sheet 113 described below is one example, and the transparent conductive sheet 113 can also be manufactured by other manufacturing methods. FIGS. 4 to 6 are schematic diagrams showing manufacturing steps (A) to (F) of the transparent conductive sheet 113.

[0044] First, as shown in Fig. 4(A), a resin layer composition is applied to a first surface 31A of a light-transmitting substrate 31 and dried to form a coating film 39 of the resin layer composition. When the light-transmitting substrate 31 has an undercoat layer on one surface, the first surface 31A is preferably the surface of the undercoat layer. Examples of methods for applying the resin composition include known application methods such as spin coating, dipping, spraying, slide coating, bar coating, roll coating, gravure coating, and die coating.

[0045] Next, as shown in FIG. 4(B), the coating film 39 is irradiated with (or heated by) ionizing radiation I such as ultraviolet light to polymerize (crosslink) the polymerizable compound, thereby hardening the coating film 39 and forming a hard coat layer (resin layer) 32.

[0046] When ultraviolet light is used as the ionizing radiation for curing the coating film 39, ultraviolet light emitted from an ultra-high pressure mercury lamp, a high pressure mercury lamp, a low pressure mercury lamp, a carbon arc, a xenon arc, a metal halide lamp, or the like can be used. Furthermore, the wavelength of the ultraviolet light can be in the 190 to 380 nm range. Specific examples of electron beam sources include various electron beam accelerators, such as Cockcroft-Waldt type, Van de Graaf type, resonant transformer type, insulating core transformer type, linear type, dynamitron type, and high frequency type. After the hard coat layer 32 is formed, the hard coat layer 32 is neutralized. For example, a voltage application type static eliminator (product name "SJ-H156A", manufactured by Keyence Corporation) can be used for neutralization.

[0047] After the hard coat layer 32 is neutralized, a conductive fiber-containing composition containing conductive fibers 35 and a dispersion medium is applied to the second surface 31B of the light-transmitting substrate 31 and dried, thereby arranging a plurality of conductive fibers 35 on the second surface 31B of the light-transmitting substrate 31, as shown in Fig. 5(C). The conductive fiber-containing composition may contain, in addition to the conductive fibers 35 and the dispersion medium, a resin component made of a thermoplastic resin or a polymerizable compound.

[0048] After arranging a plurality of conductive fibers 35 on the second surface 31B of the light-transmitting substrate 31, a composition for a light-transmitting resin containing a polymerizable compound and a solvent is applied and dried to form a coating film 30 of the composition for a light-transmitting resin, as shown in Fig. 5(D). The composition for a light-transmitting resin contains a polymerizable compound and a solvent, and may also contain a polymerization initiator or a reaction inhibitor, if necessary.

[0049] Next, as shown in FIG. 6(E), the coating film 30 is irradiated with ionizing radiation I such as ultraviolet light to polymerize (crosslink) the polymerizable compound, thereby curing the coating film 30 and forming a light-transmitting resin 36. This forms a conductive layer on the second surface 31B of the light-transmitting substrate 31. Next, as shown in FIG. 6(F), an overcoat layer 34 is formed on the second surface 33B of the conductive layer 33. This allows for the production of a transparent conductive sheet 113 comprising the light-transmitting substrate 31, the hard coat layer 32, the conductive layer 33, and the overcoat layer 34.

[0050] The transparent conductive sheet 113 obtained by the above manufacturing process can be patterned by laser etching, punching, etc. to produce a sheet of the first antenna 13. This first antenna 13 is attached to the display surface 11a of the display unit 11, and wiring is formed to electrically connect it to the first conversion unit 14, thereby obtaining a laminate of the display unit 11 and the first antenna 13 as shown in FIG.

[0051] Next, a procedure for controlling the rewriting of appeal information displayed on the electronic shelf label 10 (display unit 11) in the display system 1 of this embodiment will be described with reference to FIG. FIG. 7 is a sequence diagram showing the procedure for controlling the rewriting of appeal information displayed on the electronic shelf label 10. As shown in FIG. First, in step S11 shown in FIG. 7, the external power supply terminal 21 transmits a power supply radio wave with a center frequency of 920 MHz to the electronic shelf label 10, and starts supplying power to the electronic shelf label 10.

[0052] In step S21, the power supply radio waves transmitted from the external power supply terminal 21 are received by the first antenna 13 of the electronic shelf label 10. The power supply radio waves received by the first antenna 13 are converted into power supply electric power by the first conversion unit 14 and supplied to the drive unit 12. When the power supply electric power is supplied to the drive unit 12, the drive unit 12 enters the same state as when power is supplied from a drive power source such as a battery. Therefore, the drive unit 12 can generate and output a drive signal for rewriting the appeal information displayed on the display unit 11.

[0053] In step S31, the external display terminal 22 transmits a display radio wave with a center frequency of 2.4 GHz to the electronic shelf label 10 to instruct the electronic shelf label 10 to rewrite the information on the electronic shelf label 10. In step S22, the display radio waves transmitted from the external display terminal 22 are received by the second antenna 15 of the electronic shelf label 10. The display radio waves received by the second antenna 15 are converted by the second conversion unit 16 into a data signal of appeal information and output to the control unit 17.

[0054] In step S23, the control unit 17 transmits the data signal of the appeal information to the drive unit 12, and controls the drive unit 12 to generate a drive signal corresponding to the data signal of the appeal information based on the power supplying power supplied from the first conversion unit 14 and output the drive signal to the display unit 11. As a result, the drive signal corresponding to the data signal of the appeal information is output from the drive unit 12 to the display unit 11, and the appeal information is rewritten. Rewriting of the appeal information is completed in about 1 to 30 seconds.

[0055] In step S12, the power supply external terminal 21 stops transmitting the power supply radio waves to the electronic shelf label 10. The power supply external terminal 21 may stop transmitting the power supply radio waves when a predetermined time has elapsed since the power supply radio waves started to be transmitted in step S11, or when the power supply external terminal 21 receives a signal (transmission stop request signal) from the electronic shelf label 10 notifying that the rewriting of the appeal information has been completed.

[0056] By executing the above-described rewriting control in the display system 1, rewriting of the appeal information displayed on the electronic shelf labels 10 is completed. Note that the rewriting of the appeal information may be executed for each of the plurality of electronic shelf labels 10, or may be executed for the plurality of electronic shelf labels 10 collectively.

[0057] The electronic shelf label 10 and the display system 1 of the present embodiment described above provide the following advantages, for example. In the electronic shelf label 10 of this embodiment, the first antenna 13 provided on the display unit 11 is optically transparent and therefore does not affect the visibility of the display unit 11. Furthermore, since the first antenna 13 is provided on the display unit 11 (display surface 11a), sufficient antenna installation space can be secured even in electronic shelf labels 10 used in long, narrow spaces on product display shelves. Furthermore, the first antenna 13 is formed of a conductive layer 33 containing conductive metal nanowires. This not only enables more efficient reception of power supply radio waves but also reduces problems such as reduced transparency and moire, which are common when an antenna made of a mesh-like metal film or a transparent conductive film such as ITO is provided on the display unit 11. Therefore, the first antenna 13, electronic shelf label 10, and display system 1 of this embodiment enable more efficient reception of power supply radio waves without affecting the visibility of the display unit 11.

[0058] The electronic shelf label 10 of this embodiment does not consume power except for rewriting the appeal information, so maintenance costs can be kept lower than those of conventional electronic shelf labels that use button-type batteries. Furthermore, since no cords are required for connecting to an external power source, the electronic shelf label 10 can be easily rearranged or replaced. Furthermore, the electronic shelf label 10 of this embodiment uses electronic paper as the panel of the display unit 11, so it is possible to display and rewrite the appeal information with less power.

[0059] The first antenna 13 of this embodiment uses metal nanowires as the conductive fibers 35 (see FIG. 3) arranged therein, allowing for more appropriate adjustment of the surface resistivity. In particular, in this embodiment, silver nanowires are used as the metal nanowires, allowing for good conductivity in the first antenna 13. Furthermore, when silver nanowires are used as the conductive fibers 35, if the surface resistivity of the first antenna 13 is 3 Ω / □ or higher, the total light transmittance can be 70% or higher. Furthermore, if the surface resistivity of the first antenna 13 is 10 Ω / □, the total light transmittance can be 90% or higher. If the total light transmittance of the first antenna 13 is 80%, there is almost no impact on the visibility of the display unit 11, thereby further enhancing the product appeal effect of the electronic shelf label 10.

[0060] Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications and variations, such as the modified embodiments described below, are possible, and these are also included within the technical scope of the present invention. The effects described in the above-described embodiments are merely a list of the most preferable effects resulting from the present invention, and are not limited to those described in the embodiments. Note that the above-described embodiments and the modified embodiments described below can also be used in appropriate combinations, but detailed description thereof will be omitted.

[0061] (Variations) In the embodiment, an example has been described in which an electrophoretic method is used as the display method of electronic paper suitable for the panel of display unit 11, but this is not limiting. Any display method may be used as electronic paper suitable for the panel of display unit 11 as long as it has display retention properties that allow the displayed content to be retained even after the application of voltage is stopped. Examples of display methods that have display retention properties include a powder movement method, a twist ball method, a cholesteric liquid crystal method, and an electrochromic method. In the embodiment, an example has been described in which the display device according to the present invention is applied to an electronic shelf label 10, but the present invention is not limited to this. The display device according to the present invention can also be applied to electronic devices such as IC tags equipped with a display unit, for example.

[0062] In the embodiment, an example has been described in which the first antenna 13 receives radio waves for power supply and the second antenna 15 receives radio waves for display, but the present invention is not limited to this. A single antenna may be configured to receive radio waves for power supply and radio waves for display. In the embodiment, an example has been described in which the power supply radio waves received by the first antenna 13 are 920 MHz and the display radio waves received by the second antenna 15 are 2.4 GHz, but this is not limiting. The frequency band of the radio waves received by each antenna can be set appropriately within the range specified by law. The power supply radio waves received by the first antenna 13 may be in the range of 300 MHz to 300 GHz, for example. The display radio waves received by the second antenna 15 may also be in the range of 300 MHz to 300 GHz, for example. [Explanation of symbols]

[0063] 1 Display System 10 Electronic shelf label 11 Display section 11a Display surface 13 First Antenna 15 Second Antenna 17 Control Unit 21 External power supply terminal 22 External display terminal 33 Conductive layer

Claims

1. A display device, an external power supply terminal for transmitting electric energy by electromagnetic waves to the display device; an external display terminal that transmits display radio waves to the display device; The display device includes: a display unit that displays appeal information; a first antenna having optical transparency, provided on a display surface of the display unit, formed of a conductor including at least metal nanowires, and configured to receive electrical energy transmitted by electromagnetic waves; a second antenna for receiving radio waves for display from the external terminal for display; a control unit that controls an operation of the display device, the first antenna receives a power supply radio wave as the electrical energy from the external power supply terminal, and supplies power to the display unit based on the received power supply radio wave; the control unit, when receiving the power supply radio waves by the first antenna and the display radio waves by the second antenna, transmits a transmission stop request signal to the power supply external terminal when rewriting of the appeal information based on the received display radio waves is completed; The display system, wherein the external power supply terminal stops transmitting the power supply radio waves to the display device when the external power supply terminal receives the transmission stop request signal.

2. 2. The display system of claim 1, The display system, wherein the metal nanowire of the first antenna is a silver nanowire.

3. 3. The display system according to claim 2, A display system, wherein the conductor containing the silver nanowires has a total light transmittance of 70% or more and a haze value of 10% or less.

4. 4. The display system according to claim 1, The panel of the display unit is electronic paper. Display system.

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