JP2016173747A - Rfid tag, communication system, and electromagnetic wave control sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an RFID tag that can prevent deterioration in a communication property when it comes into contact with or gets close to an electrical conductor or a high dielectric, and that can be thin and low in cost.SOLUTION: An RFID tag 100 comprises: a laminate 10 including a first conductive layer 10a as a middle layer; an antenna 20 provided on the laminate; and an IC chip 30 connected with the antenna 20. The first conductive layer 10a has structure including a narrow part. This allows the RFID tag to prevent deterioration in a communication property when it comes into contact with or gets close to an electrical conductor or a high dielectric and to be thin and low in cost.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an RFID tag, a communication system, and an electromagnetic wave control sheet. More specifically, the present invention relates to an RFID tag including an antenna and an IC chip, a communication system including the RFID tag, and an electromagnetic wave control sheet for controlling electromagnetic waves.

  In recent years, RFID tags have been actively developed.

  For example, Patent Document 1 discloses an RFID tag that can suppress a decrease in communication performance when contacting or approaching a conductor or a high dielectric material.

  However, with the RFID tag disclosed in Patent Document 1, it has been difficult to achieve both a reduction in thickness and a reduction in cost.

  The present invention includes a laminate including one conductive layer as an intermediate layer, an antenna provided on the laminate, and an IC chip connected to the antenna, wherein the one conductive layer includes a constricted portion. An RFID tag having at least one structure including

  According to the present invention, it is possible to suppress a decrease in communication when contacting or approaching a conductor or a high dielectric, and it is possible to achieve both reduction in thickness and cost.

FIG. 1A is a plan perspective view of an RFID tag according to an embodiment, and FIG. 1B is a YZ sectional view of the RFID tag. FIGS. 2A to 2D are diagrams showing specific examples (part 1 to part 4) of a biaxially symmetric structure with a constriction, respectively. FIGS. 3A and 3B are views (No. 1 and No. 2) for explaining the configuration of the constricted biaxially symmetric structure Tr, respectively. 4A and 4B are diagrams showing dispersion characteristics of in-plane propagation waves of the constricted biaxial symmetrical structure Tr when a phase difference is given in the X-axis direction and the Y-axis direction, respectively. FIGS. 5A and 5B are diagrams showing the electric field distribution of the constricted biaxial symmetrical structure Tr when a known phase difference is applied in the X-axis direction and the Y-axis direction, respectively. It is a Smith chart (the 1) which shows the measured value of the impedance which looked at the antenna side from the IC chip in a RFID tag. It is a Smith chart (the 2) which shows the measured value of the impedance which looked at the antenna side from the IC chip in a RFID tag. It is a figure (the 1) which shows the passage characteristic of the in-plane propagation wave of the laminated structure which has the biaxial symmetry structure Tr with a constriction. FIG. 11 is a diagram (part 2) illustrating pass characteristics of in-plane propagation waves of a laminated structure having a constricted biaxially symmetric structure Tr; It is the schematic which shows the measuring method of communication distance. It is a graph which shows the thickness d of a 1st spacer layer, and the relationship of a communication ratio. It is a graph which shows the relationship between the magnitude | size (height) of the triangle of the biaxial symmetry structure Tr with a neck, and a communication ratio. FIG. 13A is a plan perspective view of the RFID tag of the modification, and FIG. 13B is a YZ sectional view of the RFID tag of the modification. 14A is a plan perspective view of an electromagnetic wave control sheet including a conductive layer in which a plurality of constricted biaxially symmetric structures are periodically arranged. FIG. 13B is a YZ cross-sectional view of the electromagnetic wave control sheet. is there. FIG. 15A is a plan perspective view of an electromagnetic wave control sheet including a single constricted biaxially symmetric structure in a conductive layer, and FIG. 15B is a cross-sectional view of the electromagnetic wave control sheet. FIG. 16A and FIG. 16B are diagrams for explaining another example of a constricted biaxial symmetry structure. FIG. 17 (A) to FIG. 17 (C) are diagrams for explaining specific examples of the uniaxial symmetry structure with a constriction. 18A and 18B are diagrams for explaining another example of a biaxially symmetric structure with a constriction, and FIG. 18C is another example of a uniaxial symmetric structure with a constriction. It is a figure for demonstrating. FIG. 19A is a diagram for explaining another example of a uniaxial symmetry structure with a constriction, and FIG. 19B is a diagram for explaining a specific example of a non-axisymmetric structure with constriction. FIG. 19C is a view for explaining another example of a constricted biaxial symmetry structure. 20A and 20B are diagrams for explaining another example of a periodic array having a plurality of constricted two-axis symmetrical structures. FIG. 21A and FIG. 21B are diagrams for explaining a conventional RFID tag.

  Hereinafter, an embodiment of the present invention will be described with reference to FIGS. FIG. 1A shows a plan perspective view of an RFID tag 100 according to an embodiment. FIG. 1B shows a YZ cross-sectional view of the RFID tag 100.

  As an example, as shown in FIGS. 1A and 1B, the RFID tag 100 is provided with a stacked body 10 including a first conductive layer 10a as an intermediate layer and the stacked body 10. An antenna 20 and an IC chip 30 connected to the antenna 20 are provided. Here, the RFID tag 100 is a passive tag, but may be an active tag equipped with a battery.

  Below, it demonstrates using the XYZ three-dimensional orthogonal coordinate system which makes the lamination direction of the laminated body 10 a Z-axis direction suitably. Here, the antenna 20 and the IC chip 30 are disposed on the + Z side of the stacked body 10.

  The IC chip 30 stores a unique ID number. This ID number can be read using an RW device (reader / writer device).

  The antenna 20 includes a meandering portion as shown in FIG. 1A, and a communication antenna (loop antenna, patch antenna, dipole antenna, spiral antenna, helical antenna, slit) normally used in an RFID tag. Antenna).

  In addition to the first conductive layer 10a, the stacked body 10 includes a second conductive layer 10b as a ground layer disposed on the −Z side of the first conductive layer 10a, and first and second conductive layers. A first spacer layer 10c made of a dielectric disposed between 10a and 10b, and a second spacer layer 10d made of a dielectric disposed between the first conductive layer 10a and the antenna 20.

  The material of each conductive layer (conductive material) may be a metal such as gold, platinum, silver, nickel, chromium, aluminum, copper, zinc, lead, tungsten, iron, etc. It may be a resin mixture mixed with conductive carbon black, or a film of conductive resin. The metal or the like may be processed into a foil shape, a plate shape, a sheet shape, a film shape, or the like. Or you may have the structure by which the metal thin layer of film thickness, for example, 600 mm, was formed on the synthetic resin film. What transferred metal foil to base materials, such as a film or cloth, may be used. Further, a metal particle-based conductive ink (for example, resistivity 10Ω / □ or less) may be applied to the first spacer layer 10c and the second spacer layer 10d.

  As a material of each spacer layer, for example, a dielectric material such as PET (Polyethylene Terephthalate resin) is suitable. In addition, the material of the actual spacer layer may be a relatively transparent material (at least the inside can be seen through). In addition, a resin having a dielectric constant as low as possible, a foam material containing air, sponge, urethane, fiber, and the like are preferable. Furthermore, examples of the organic material include porous bodies such as high molecular organic materials such as rubber, thermoplastic elastomer, various plastics, wood, and paper. Examples of the rubber include natural rubber, isoprene rubber, butadiene rubber, styrene-butadiene rubber, ethylene-propylene rubber, ethylene-propylene-diene rubber (EPDM rubber), ethylene-vinyl acetate rubber, butyl rubber, halogenated butyl rubber, chloroprene. Synthetic rubber such as rubber, nitrile rubber, acrylic rubber, ethylene acrylic rubber, epichlorohydrin rubber, fluorine rubber, urethane rubber, silicon rubber, chlorinated polyethylene rubber, hydrogenated nitrile rubber (HNBR), their derivatives, or These may be modified by various modification treatments. These rubbers can be used alone or in combination. Examples of thermoplastic elastomers include chlorinated polyethylenes such as chlorinated polyethylene, ethylene copolymers, acrylics, ethylene acrylic copolymers, urethanes, esters, silicones, styrenes, amides, olefins, etc. Various thermoplastic elastomers and their derivatives are mentioned. Further, various plastics include, for example, chlorine resins such as polyethylene, polypropylene, AS resin, ABS resin, polystyrene, polyvinyl chloride, and polyvinylidene chloride; polyvinyl acetate, ethylene-vinyl acetate copolymer, fluororesin, and silicone resin. , Thermoplastic resins such as acrylic resin, nylon, polycarbonate, polyethylene terephthalate, alkyd resin, unsaturated polyester, polysulfone, polyimide resin, urethane resin, phenol resin, urea resin, epoxy resin, etc., and their derivatives Furthermore, a copolymer, a recycled resin, etc. are mentioned. The above materials can be used as they are, or combined and modified. It is preferable to foam. A typical low density dielectric material is a foamed resin such as a styrofoam resin. Examples of thermoplastic elastomers include chlorinated polyethylenes such as chlorinated polyethylene, ethylene copolymers, acrylics, ethylene acrylic copolymers, urethanes, esters, silicones, styrenes, amides, olefins, etc. Various thermoplastic elastomers and their derivatives are mentioned. The above materials can be used as they are, or combined and modified. It is preferable to foam. A typical low density dielectric material is a foamed resin such as a styrofoam resin. In addition to the above, paper materials such as cardboard, wood, glass, glass fiber, and earth-based materials can also be used. In addition, the base material or adhesive layer of the wireless IC tag can be used as a spacer material.

  Each spacer layer can be realized at a low cost by being made of a material that does not substantially contain a magnetic material as described above.

  As shown in FIG. 1A, the first conductive layer 10a has a two-dimensional periodic array structure in which a plurality of (for example, eleven) unit structures are periodically arrayed two-dimensionally along the XY plane. Yes. Each unit structure is insulated from other unit structures and surroundings. Here, the periodic arrangement of the plurality of unit structures is a staggered arrangement, but may be another periodic arrangement such as a matrix arrangement.

  Each unit structure includes a constricted portion and a pair of tapered portions that are connected via the constricted portion and become wider in the X-axis direction as they are separated from the constricted portion in the Y-axis direction. That is, the tip ends of the pair of tapered portions are coupled (connected) via the constricted portion. Each unit structure may be integrally molded, or may be joined after a plurality of parts are molded separately.

  The constricted portion may have a certain width in at least one of the X-axis direction and the Y-axis direction, or at least one width in the X-axis direction and the Y-axis direction may be substantially zero. That is, the constricted portion may have a planar shape (a shape viewed from the + Z side) in any of a planar shape (see FIG. 3A), a linear shape, or a point shape. When the planar shape of the constricted portion is a linear shape or a point shape parallel to the X axis, the tip portions of the pair of tapered portions are substantially directly coupled to each other. In this case, the “constricted portion” may be considered to mean an interface between a pair of tapered portions.

  Here, the shape of the constricted portion is, for example, a rectangle (surface shape), but may be another shape.

  The pair of taper portions are in a positional relationship to sandwich the constricted portion in the Y-axis direction. Further, the pair of taper portions have the same shape and the same size, and are arranged in axial symmetry (line symmetry) with respect to the uniaxial axis (X axis) and the other axis (Y axis) that pass through the constricted portion. Therefore, hereinafter, the unit structure is also referred to as a “bending biaxial symmetry structure”.

  As a planar shape (a shape viewed from the + Z side) of each tapered portion in the constricted biaxial symmetry structure, for example, a trapezoid (eg, an isosceles trapezoid), a triangle (eg, an equilateral triangle, an isosceles triangle, etc.), a sector, a drop Part of the shape can be cited (FIGS. 2A to 2D). 2A to 2D, the side surface (tapered surface) of each tapered portion is a flat surface, but may be a curved surface. Further, for example, other portions may be coupled to the maximum width portion of the tapered portion as in the drop shape shown in FIG.

  When the first conductive layer 10a is manufactured, for example, a plurality of constricted biaxially symmetric structures are formed by performing notch processing on one conductive film to be attached on the first or second spacer 10c, 10d. Alternatively, it may be formed by pasting a plurality of constricted biaxially symmetric structures formed in advance on the first or second spacer layer 10c, 10d, or forming a constricted biaxially symmetric structure. Each part may be formed and processed, and each part may be affixed on the first or second spacer layer 10c, 10d to form a constricted biaxial symmetry structure. As described above, the first conductive layer 10a having a plurality of constricted biaxial symmetry structures can be easily manufactured.

  Here, a unit structure having a constricted portion (for example, a constricted biaxial symmetry structure) has an in-plane propagation wave propagating in the X-axis direction or the Y-axis direction inside the structure. That is, the unit structure having the constricted portion has spatial harmonics in the Brillouin zone on the wave number space due to the periodicity of the structure. Among these, in the fast wave region where the phase velocity is faster than the speed of light, an external electromagnetic wave can be coupled to the in-plane propagation wave. This means that the excited in-plane propagation wave can be emitted to the outside.

  In the RFID tag 100, since the antenna 20 is arranged on the two-axis symmetric structure with the constriction via the second spacer layer 10d, the in-plane propagation wave is radiated from the two-axis symmetric structure with the constriction and the antenna 20 and the electromagnetic wave. Can be combined. Thus, the constricted biaxial symmetry structure has a function of reinforcing (increasing) the gain (operation gain) of the antenna 20.

  In this case, even if the RFID tag 100 is brought into contact with or close to a conductor or a high dielectric, the IC chip 30 coupled to the antenna 20 can receive power from an external electromagnetic wave, or information from the IC chip 30 can be received. Can be radiated (transmitted) on an electromagnetic wave.

  The resonance layer of the antenna 20 is determined by the size corresponding to the wavelength corresponding to the radio wave of a specific frequency, and any type can be used as long as it is normally used.

  FIG. 3A shows the configuration of a biaxially symmetric structure Tr with a constriction in which the shape of each taper portion is an equilateral triangle, and FIG. 3B shows a biaxial symmetric structure Tr with a constriction (here, 1 for convenience) YZ sectional view of the laminated structure LS arranged on the second conductive layer 10b via the first spacer layer 10c is shown.

  FIGS. 4A and 4B show the dispersion characteristics of the in-plane propagation wave of the constricted biaxial symmetry structure Tr when the phase difference in the X-axis direction and the Y-axis direction is given, respectively. The “phase difference in the X-axis direction” means the phase shift of the in-plane propagation wave before and after passing when the in-plane propagation wave passes (propagates) in the X-axis direction through the biaxially symmetric structure Tr having a constriction. Means. “Y-axis direction phase difference” means a phase shift of the in-plane propagation wave before and after passage when the in-plane propagation wave passes through the biaxially symmetric structure Tr with a constriction in the Y-axis direction (propagation) To do. The horizontal axis of FIG. 4 (A) and FIG. 4 (B) is ka / π. However, “k” indicates a wave vector 2π / λ (λ is the wavelength of the in-plane propagation wave), and “a” indicates the X-axis direction in a two-dimensional periodic array structure having a united biaxial symmetry structure Tr or The repetition period in the Y-axis direction is shown.

  Here, as shown in FIG. 3A, for example, in the constricted biaxial symmetrical structure Tr, the height of the tapered portion is h = 25.0 mm, and the width of the constricted portion in the X-axis direction is a = 1. .55 mm, the width of the constricted portion in the Y-axis direction is b = 2.0 mm, and the distance between the tapered portion and the periphery is c = 1.225 mm. The thickness of the first spacer layer 10c is d = 0.364 mm, and the relative dielectric constant is 3.37. From the measurement results under these conditions, it was found that both the X-axis direction and the Y-axis direction have a propagation mode in the radiation region at 915 MHz. That is, by using 915 MHz as the communication frequency of the RFID tag 100, the in-plane propagation wave can be radiated most efficiently from the constricted biaxially symmetric structure Tr.

  In FIGS. 4A and 4B, the region on the left side of the broken line is an effective radiation region, that is, a region where the radiation effect of the in-plane propagation wave can be obtained relatively well. From this, it can be seen that the phase difference applied in each of the X-axis direction and the Y-axis direction is preferably smaller than a certain phase difference.

  FIG. 5A and FIG. 5B show the calculation results of the electric field distribution when a known phase difference is given in the X-axis direction and the electric field distribution when a known phase difference is given in the Y-axis direction, respectively. Is shown in a grayscale image. From this calculation result, it can be seen that the electromagnetic wave propagating in the plane (in-plane propagation wave) has the same mode regardless of whether the phase difference is given in the X-axis direction or the Y-axis direction.

  FIG. 6 shows a measured value of impedance of the RFID tag 100 as viewed from the IC chip 30 on the antenna structure 20 side in a Smith chart.

  That is, FIG. 6 shows the measured impedance values when h is the height of the tapered portion of the equilateral triangle of the constricted biaxially symmetric structure TRr and h is a parameter. From the measurement results, it can be seen that the impedance is relatively close to the matching region of the IC chip 30. Here, the first spacer 10c is a PET film having a thickness d = 0.364 mm (see FIG. 3B).

  Further, by changing the size of the constricted biaxially symmetric structure Tr, that is, the size of the tapered portion (the height h of the tapered portion), the resonance frequency of the constricted biaxially symmetric structure Tr is changed. It can be seen that the resonance frequency decreases as the symmetrical structure Tr increases.

  Further, in FIG. 7, in the laminated structure LS, measured impedance values when the antenna 20 is viewed from the IC chip 30 in the RFID tag 100 when the thickness d (mm) of the first spacer layer 10c is changed are shown. Shown in Smith chart. It can be seen that as the thickness of the first spacer layer 10c increases, the resonant frequency of the constricted biaxially symmetric structure Tr increases. Here, h = 26.0 mm.

  From this, the impedance matching between the IC chip 30 and the antenna 20 can be adjusted by adjusting the thickness of the first spacer layer 10c and the size of the constricted biaxially symmetric structure Tr.

  FIG. 8 shows the pass characteristics of the in-plane propagation wave in the constricted biaxial symmetry structure Tr in the stacked structure LS shown in FIG.

  More specifically, FIG. 8 shows frequency characteristics when the height of the tapered portion of the equilateral triangle of the constricted biaxially symmetric structure Tr shown in FIG. 3A is h, and h is a parameter. ing. FIG. 8 shows that the passband of the in-plane propagation wave shifts to the lower frequency side as the size of the constricted biaxial symmetry structure Tr increases. Here, d = 0.364 mm.

  In FIG. 9, in the laminated structure LS shown in FIG. 3B, the in-plane propagation wave of the constricted biaxially symmetric structure Tr when the thickness d (mm) of the first spacer layer 10c is changed. Pass characteristics are shown. Here, the height h of the equilateral triangle is set to 25.5 mm. In this case, it can be seen that as the thickness d (mm) of the first spacer layer 10c increases, the passband of the in-plane propagation wave shifts to the higher frequency side.

  8 and 9, it can be seen that the operating characteristics of the RFID tag 100 can be adjusted by changing the size of the constricted biaxially symmetric structure Tr and the thickness of the first spacer 10c.

  FIG. 10 schematically shows a method for measuring a communication distance. Here, as an example, in a state in which the RFID tag 100 is attached to a metal surface, a communication distance that is the maximum communicable distance is searched (measured) while changing the distance L between the RFID tag 100 and the RW device.

  FIG. 11 shows the thickness d of the first spacer layer 10c when the height h (mm) of the tapered portion of the regular triangle of the constricted biaxially symmetric structure Tr is constant in the state shown in FIG. The relationship between (mm) and the communication ratio is shown in a graph. The horizontal axis in FIG. 11 is d (mm), and the vertical axis is the communication ratio (%). The communication ratio is calculated by (measured communication distance / communication distance in free space) × 100 (%) based on the measured communication distance. Even when the RFID tag 100 is attached to, for example, a metal surface, a communication ratio of 30% or more is realized regardless of the value of d, and d = 1.004 mm and the communication ratio is 72%. In either case, it can be seen that the communication state is improved.

  FIG. 12 shows the height h (mm) of the equilateral triangular tapered portion of the biaxial symmetry structure when the thickness d (mm) of the first spacer layer 10c is constant in the state shown in FIG. The relationship of communication ratio is shown in the graph. The horizontal axis of FIG. 12 is h (mm), and the vertical axis is the communication ratio (%). Here, as an example, d = 0.464 mm is set. Even when the RFID tag 100 is attached to, for example, a metal surface, a communication ratio of 15% or more is realized regardless of the value of h, and the communication ratio is 33% when h = 26 mm. In either case, it can be seen that the communication state is improved.

  The frequency used for communication of the RFID tag 100 is not particularly limited, but any single frequency or a plurality of frequencies can be selected including a range of 300 MHz to 300 GHz. The range of 300 MHz to 300 GHz includes UHF band (300 MHz to 3 GHz), SHF band (3 GHz to 30 GHz), and EHF band (30 GHz to 300 GHz).

  The RFID tag 100 preferably covers at least a part of the outer surface with a dielectric material. This dielectric material may have magnetism. As a dielectric material for coating, for example, a hard cover and a soft cover that gives flexibility can be considered. As the hard cover, the above-mentioned various plastics and inorganic materials, wood, and the like can be considered. What mixed the inorganic material etc. with resin may be sufficient. As the soft cover, the above-mentioned thermoplastic elastomer and various synthetic rubbers can be used. A hard cover is made of a material that can give rigidity, and a soft cover is made of a material that can give flexibility. As the material, materials exemplified as dielectric materials, other inorganic materials, paper-based, wood-based, earth-based, glass-based, and ceramic-based materials can be used. It is optional to add a filler to these materials or to perform crosslinking. Moreover, you may have adhesiveness and adhesiveness. A foam material can also be used. As the covering material, the materials mentioned as the materials for the first spacer layer 10c and the second spacer layer 10d can be used as they are. Combinations of polymers and glass fibers and other composite materials are often used. In particular, an appropriate material is selected to provide environment resistance, durability, impact resistance, and insulation, and coating is performed.

  By the way, conventionally, an RFID tag is used as an information transmission medium by being mounted on, for example, a slip, a certificate, a card, a label, or the like (hereinafter referred to as a slip).

  Such slips are still used in logistics, logistics, distribution, inventory management, process management, etc. as work instructions, request forms, purchase orders, delivery slips, bills, slips, kanbans, and the like.

  However, it has been impossible to attach slips in which RFID tags are incorporated or pasted to a communication obstruction member (for example, a conductive member or a high dielectric constant member) that obstructs communication of the RFID tag as in the past.

  In actual manufacturing industry, transportation industry, sales industry, rental industry, etc., there are a lot of communication obstruction members in the environment where RFID tags are used, and RFID objects are attached to objects including communication obstruction members. There are also many needs to manage.

  Therefore, the RFID tag 100 according to the present embodiment can be used in proximity to or attached to such a communication obstructing member, so that the range of its use is greatly expanded and the utility is extremely high.

  Specifically, containers made of conductive materials and high dielectric constant materials, products including communication obstruction members made of conductive materials and communication obstruction members made of high dielectric constant materials, intermediate products, parts, vehicles, pallets, cars, forklifts , Container, bag, packaging, case, return box, conductive box, measuring instrument, equipment, heavy machinery, fixtures, fixtures, machinery, equipment, components, fire extinguisher, gas cylinder, cylinder, tank, vehicle, transport machine, mounting machine Even if the RFID tag 100 is directly attached as an IC tag, kanban, slip, certificate, card or label to a pipe, a metal pipe, etc., wireless communication can be performed. As a result, the target products for distribution management, inventory management, distribution management, information management and the like are expanded, and by supporting the international frequency of the RFID frequency, management in the case of import / export is facilitated.

  The RFID tag 100 of the present embodiment described above includes a stacked body 10 including the first conductive layer 10a as an intermediate layer, an antenna 20 provided on the stacked body, and an IC chip 30 connected to the antenna 20. The first conductive layer 10a includes a structure having a constricted portion.

  In this case, the gain (operation gain) of the antenna 20 is enhanced by exciting and radiating the in-plane propagation wave of the first conductive layer 10a by an external electromagnetic wave.

  For this reason, the thickness of the layer (for example, the first spacer layer 10c) on the side opposite to the antenna 20 (the mounting surface side to the object) with respect to the first conductive layer 10a in the stacked body 10 is made thin, so Even if it is in contact with or close to a body or a high dielectric material, it is possible to suppress a decrease in communication performance. The first conductive layer 10a is easy to manufacture.

  As a result, according to the RFID tag 100, it is possible to suppress a decrease in communication when contacting or approaching a conductor or a high dielectric, and it is possible to achieve both a reduction in thickness and a reduction in cost.

  In addition, the structure having the constricted portion includes a pair of tapered portions that are connected via the constricted portion and become wider as the distance from the constricted portion increases, so that the radiation of the in-plane propagation wave can be improved and the deterioration of the communication property can be stabilized. Can be suppressed.

  In addition, since the two tapered portions have the same shape and the same size, the radiation property of the in-plane propagation wave can be improved.

  In addition, since the two tapered portions are arranged symmetrically with respect to one axis (X axis) passing through the constricted portion, the radiation property of the in-plane propagation wave can be further improved.

  Further, since the two taper portions are arranged symmetrically with respect to the other axis (Y axis) perpendicular to one axis (X axis) through the constricted portion, the radiation property of the in-plane propagation wave is further improved. Can do.

  In addition, since there are a plurality of structures having a constricted portion and the plurality of structures are periodically arranged, a synergistic effect of in-plane propagation wave radiation can be obtained between the structures.

  The plurality of structures having the constricted portions are arranged in a staggered manner. In this case, the structure having the constricted portion in the first conductive layer 10a can be arranged with high density, and the radiation density of the in-plane propagation wave can be increased.

  The stacked body 10 includes a second spacer layer 10d disposed between the first conductive layer 10a and the antenna 20, and a side opposite to the second spacer layer 10d with respect to the first conductive layer 10a. And a first spacer layer 10c disposed on the first spacer layer 10c.

  In this case, it is possible to stably insulate between the antenna 20 and the first conductive layer and between the first conductive layer and the object.

  The stacked body 10 includes a second conductive layer 10b disposed on the side opposite to the first conductive layer 10a with respect to the first spacer layer 10c, and the size of the second conductive layer 10b is: It is not less than the size of the first conductive layer 10a.

  In this case, the influence from the installation position and environment of the RFID tag 100 can be reduced.

  In addition, when at least one of the first and second spacer layers 10c and 10d is made of polyethylene terephthalate or foam, it is possible to reduce the weight and thickness.

  Further, when at least one of the second spacer layer 10d and the second conductive layer 10b has adhesiveness or adhesiveness, the antenna 20 and the IC chip 30 are attached to the stacked body 10 or the RFID tag 100 is attached to an object. Can be easily attached.

  In addition, when at least a part of the outer surface of the RFID tag 100 is covered with a dielectric material (dielectric film), the influence of unnecessary electromagnetic waves from the outside and the influence from the surrounding environment are reduced, thereby further improving the communication improvement effect. Can be improved.

  Further, when at least a part of the outer surface of the RFID tag 100 is covered with a dielectric material, durability, weather resistance, impact resistance, printing characteristics, and the like can be imparted.

  In addition, the RFID tag 100 alone or in combination with an IC tag including an IC chip and an antenna and an electromagnetic wave control sheet can be used for products including conductors and high-dielectrics, intermediate products, parts, containers, transportation tools, moving means, etc. On the other hand, even if it is directly attached as an information transmission medium such as a slip, certificate, card, label, etc., it can communicate with the IC chip wirelessly.

  In the above-described embodiment, the first conductive layer 10a has a two-dimensional periodic structure having a united biaxial symmetry structure as a unit. However, the present invention is not limited to this. For example, like the RFID tag 200 of the modification shown in FIGS. 13A to 13B, the first conductive layer may have only one biaxial symmetry structure. The first conductive layer may have a one-dimensional periodic structure in which biaxially symmetric structures are periodically arranged in one dimension. Note that the biaxial symmetry structure does not necessarily have to be periodically arranged. In either case, the constricted biaxial symmetry structure needs to be insulated from the surroundings and other constricted biaxial symmetry structures.

  Further, as shown in FIGS. 14A and 14B, the laminate 10 of the RFID tag 100 can be used as an electromagnetic wave control sheet. In the electromagnetic wave control sheet, as shown in FIGS. 15A and 15B, the first conductive layer may have only one biaxial symmetry structure.

  The electromagnetic wave control sheet composed of such a laminate 10 can achieve improved communication without depending on the type of adherend, simply by superimposing a commercially available wireless IC tag. Further, impedance adjustment is performed without using processes such as lead wiring, connection, and solder for exchanging radio wave signals between the electromagnetic wave control sheet and the IC chip of the wireless IC tag, so that resonance frequency adjustment and communication improvement can be realized.

  Note that the RFID tag and the electromagnetic wave control sheet may not have the second conductive layer 10b. Even in this case, the same effect as the above-described embodiment can be obtained. However, the second conductive layer 10b is a useful component in that a state in which the second conductive layer 10b is brought into contact with the conductor can be set in advance, and a stable operation can be ensured under this state.

  The spacer layer only needs to be able to insulate between the antenna 20 and the first conductive layer 10a or between the first and second conductive layers 10b. For example, a recess, an opening, a notch, or the like is formed. Also good.

  In addition, the structure including the constricted portion in the first conductive layer is not limited to the structure described in the embodiment and the modification example, and can be changed as appropriate. Even in the structure including the constricted portion exemplified below, the same effect can be obtained although the degree is slightly inferior to the structure including the constricted portion in the embodiment and the modification.

  For example, the side surface (taper surface) of the tapered portion of the constricted biaxial symmetry structure may be a curved surface (curved in a plan view) as shown in FIGS. 16 (A) and 16 (B).

  Also, for example, as shown in FIGS. 17A to 17C, the structure including the constricted portion may be a uniaxial symmetrical structure that is targeted only with respect to one axis. In FIG. 17A, the pair of tapered portions have the same shape and size. In FIG. 17B, the pair of taper portions have the same shape and different size (different sizes). In FIG. 17C, the pair of tapered surfaces of each tapered portion is not axially symmetric.

  Further, for example, as shown in FIGS. 18A to 18C, in the structure including the constricted portion, a pair of tapered portions may be directly coupled. In the two-axis symmetric structure with a constriction in FIG. 18A, the constricted portion has a planar shape (a linear shape in a plan view). In the biaxially symmetric structure with a constriction in FIG. 18B, the constricted portion is linear (point-like in plan view). In the one-axis symmetric structure with a constriction in FIG. 18C, the constricted portion is planar (linear in plan view).

  Further, for example, as shown in FIG. 19A, the pair of taper portions may have a deformed constricted uniaxial symmetry structure. Further, as shown in FIG. 19B, the pair of taper portions may be a non-axisymmetric structure with an irregular shape. Further, as shown in FIG. 19C, a biaxial symmetrical structure in which a pair of tapered surfaces of each tapered portion is substantially parallel may be used. That is, the taper angle of each taper portion can be appropriately changed within a range that does not result in reverse taper.

  In addition, for example, as shown in FIG. 20A, the arrangement of a plurality of constricted two-axis symmetrical structures may be a periodic arrangement in which the constricted two-axis symmetrical structures are staggered vertically and horizontally. As shown in FIG. 20 (B), the two-axis symmetric structure with a constriction may be periodically arranged in a matrix. Note that the arrangement in FIG. 20A can be arranged at a higher density than the arrangement in FIG. As described above, the arrangement of the constricted biaxial symmetry structure is preferably periodic and regular, but may not be regular.

  Note that the first conductive layer only needs to have at least one structure including a constricted portion, and the peripheral portion of the structure including the constricted portion in the first conductive layer may or may not be present. .

  A wireless communication system can also be constructed including the RFID tag 100 of the above embodiment and the RW device (communication device) that performs at least one of reading and writing of information with respect to the RFID tag 100 by wireless communication. In this case, it is possible to realize a wireless communication system that can exchange information accurately. Furthermore, this wireless communication system can also be configured to include a management device that manages information read by the communication device.

  For example, RFID tags 100 are affixed to a large number of metal articles, they are sequentially flowed on a conveyor (with a certain interval between them), and they are distributed and managed (in and out) at an antenna gate portion installed at an arbitrary location. Management) and traceability management can be constructed.

  Information that can be transmitted by the RFID tag 100 can include not only the product ID, but also history information and special information, as well as work instructions, request forms, delivery slips, purchase orders, etc. Management data can be expected to improve productivity such as yield improvement and cost reduction.

  Below, the background to which the inventor of the present invention came up with the above embodiment will be described.

  In recent years, interest in RFID (Radio Frequency Identification) tags has increased. An RFID tag is a type of wireless IC tag, and generally includes an LSI (Large Scale Integrated circuit) chip, an antenna, and an external resin for molding them.

  The size (outer diameter) of the RFID tag varies from 0.3 mm (sesame grain size) to a coin size of 20 to 30 mm in diameter, an IC card size, and the like. Also, there are a battery mounted type and a battery non-mounted type, the former being called an active tag and the latter being called a passive tag.

  The LSI chip built in the RFID tag includes an antenna, a transmission / reception unit, a control unit, and a memory. A unique identification code (unique ID) is stored in the memory, and this unique ID is read by an RFID tag reader / writer (hereinafter simply referred to as a reader / writer). Reading of the unique ID of the RFID tag by the reader / writer is performed by wireless communication (wireless communication) via an RFID tag antenna (hereinafter simply referred to as an antenna). This wireless communication includes a radio wave system and an electromagnetic induction system.

Generally, when an RFID tag is attached to a metal, the characteristics change greatly. For example, in the case of an electromagnetic induction type RFID tag, an eddy current flows when the magnetic flux enters the metal, which acts to cancel the magnetic flux. As a result, the communication distance (communication area) is significantly shortened and communication is impossible in the worst case. In this case, if the RFID tag is attached at a certain distance or more away from the metal, the influence from the metal is reduced.

  Also, in the case of a radio frequency type RFID tag, radio waves are reflected on the metal surface and a multipath phenomenon occurs, and reading of information on the RFID tag becomes unstable. Since the power conversion efficiency is deteriorated, the update distance is deteriorated similarly to the electromagnetic induction method.

  Also in this case, the influence from the metal can be reduced by separating the RFID tag attachment position from the metal by a certain distance or more.

  Many products and products are made of metallic materials. For this reason, there is a metal-compatible RFID tag that can be attached to a metal and has already been commercialized.

  The metal-compatible RFID tag is attached to the metal so that the antenna (RFID tag antenna) is separated from the metal by a sufficient distance or the RF absorbing material is sandwiched between the RFID tag and the metal.

FIG. 21A is a cross-sectional view showing a configuration of a conventional metal-compatible RFID tag 1000. The metal-compatible RFID tag 1000 shown in the figure has a configuration in which a metal reflector 101, a spacer portion 102, a substrate material portion 103, and PET 104 are sequentially laminated. An RFID tag is mounted on the substrate material portion 103, and an LSI chip 111 is provided in the approximate center thereof, and antennas (RFID tag antennas) 112 are provided on both side surfaces thereof.
The RFID tag includes an LSI chip 111 and an antenna 112. The LSI chip 111 is integrated with a control unit, a transmission / reception unit, a memory, and the like. As the antenna 112, a dipole antenna is often used.

The metal reflection plate 101 is a thin plate (plate) attached to a metal via an adhesive (not shown), and reflects the RF reflected by the metal.
The spacer portion 102 is made of a dielectric material, foamed polystyrene, plastic, or the like, and is used to keep the distance between the metal to which the metal-compatible RFID tag 100 is attached and the antenna 112 mounted on the substrate material portion 103 above a certain level. A material having a function as an RF absorber is also used.

  In the conventional metal-compatible RFID tag 1000 configured as described above, it is necessary to increase the thickness of the spacer portion 102. Therefore, the thickness of the metal-compatible RFID tag 100 is very large, difficult to handle, and limited in use. Has been.

  By the way, it is known that if an element having a high surface impedance can be disposed in the vicinity of the antenna, the energy incident on the impedance surface is reflected in the same phase by the high surface impedance and the antenna performance is improved.

As a sheet-like structure having a high surface impedance, EBG (Electromagnetic
There is a BandGap) structure, and the sheet-like structure and the IC chip are placed on the sheet-like structure, and the antenna conductor and the IC chip are matched at the common-phase reflection frequency of the sheet-like structure. A method has also been proposed (see, for example, Patent Document 1).

  In Patent Document 1, as shown in FIG. 21B, the sheet-like structure includes a unit structure 5 of the EBG structure 3, and the unit structure 10 includes a top electrode 11, a ground electrode 12, and a top electrode 11. And a ground electrode 12, a dielectric sandwiched between the top electrode 11 and the ground electrode 12, and a floating capacitor electrode 15 disposed in the dielectric.

  However, the sheet-like structure of the antenna device described in Patent Document 1 includes a step of forming a via, and thus the manufacturing process itself is complicated, and it is difficult to manufacture at a low cost.

  Therefore, the inventor has come up with the above-described embodiment and modified examples in order to deal with the above problems.

  DESCRIPTION OF SYMBOLS 10 ... Laminated body, 20 ... Antenna, 30 ... IC chip, 100 ... RFID tag.

Japanese Patent No. 5554395

Claims (20)

A laminate including one conductive layer as an intermediate layer;
An antenna provided on the laminate;
An IC chip connected to the antenna,
The one conductive layer is an RFID tag having at least one structure including a constricted portion.   2. The RFID tag according to claim 1, wherein the structure includes a pair of tapered portions that are connected via the constricted portion and become wider as the distance from the constricted portion increases.   The RFID tag according to claim 2, wherein the pair of taper portions have the same shape and the same size.   4. The RFID tag according to claim 3, wherein the pair of tapered portions are arranged symmetrically with respect to one axis passing through the constricted portion.   5. The RFID tag according to claim 4, wherein the pair of taper portions are arranged symmetrically with respect to another axis that passes through the constricted portion and is orthogonal to the one axis.   The RFID tag according to any one of claims 2 to 5, wherein each of the pair of taper portions has a triangular shape or a trapezoidal shape.   The RFID tag according to any one of claims 2 to 5, wherein each of the pair of taper portions is part of a drop shape.   The RFID tag according to any one of claims 2 to 5, wherein each of the pair of taper portions has a fan shape.   The RFID tag according to claim 1, wherein the one conductive layer includes a plurality of the structures.   The RFID tag according to claim 9, wherein the plurality of structures are regularly arranged. The laminate is
An insulating layer disposed between the one conductive layer and the antenna;
The RFID tag according to claim 1, further comprising: another insulating layer disposed on a side opposite to the one insulating layer with respect to the one conductive layer. The laminate includes another conductive layer disposed on the side opposite to the one conductive layer with respect to the other insulating layer,
The RFID tag according to claim 11, wherein the size of the another conductive layer is equal to or larger than the size of the one conductive layer.   The RFID tag according to claim 12, wherein the another conductive layer has adhesiveness or adhesiveness.   14. The RFID tag according to claim 11, wherein at least one of the one and another insulating layer has adhesiveness or adhesiveness.   The RFID tag according to any one of claims 11 to 14, wherein at least one of the one and another insulating layers is made of polyethylene terephthalate.   The RFID tag according to any one of claims 11 to 14, wherein at least one of the one and another insulating layer is made of a foam.   The RFID tag according to claim 1, wherein at least a part of the outer surface of the RFID tag is coated with a dielectric material. RFID tag according to any one of claims 1 to 17,
A communication apparatus that performs at least one of reading and writing of information with respect to the RFID tag by wireless communication.   The communication system according to claim 18, further comprising a management device that manages the information read by the communication device. A conductive layer;
Two insulating layers individually disposed on both sides of the one conductive layer,
The electromagnetic wave control sheet, wherein the one conductive layer includes at least one structure having a constricted portion.