RFID tag coil

Abstract

This invention provides a coil that exhibits good characteristics even when used by attaching to or embedding it in a tire, and which is combined with a substrate carrying an RF chip and a patterned coil connected to the RF chip to form an RFID tag. The coil (30) is held in a housing (75) that houses the substrate (90) and surrounds the substrate (90). A first end of the coil (30) extends from the substrate (90) to form a first element (50) of an antenna, and a second end of the coil (30) extends from the substrate (90) to form a second element (60) of an antenna. The first element (50) and the second element (60) are arranged parallel to each other, and the extension length of the first element (50) is longer than that of the second element (60). The coil (30) and the patterned coil (40) form a coupling transformer (20), and the number of turns of the coil (30) is smaller than the number of turns of the patterned coil (40).

Description

Technical Field

[0001] This invention relates to coils for RFID tags. Background Technology

[0002] Patent Document 1 (Japanese Re-evaluation No. 2007-083574) discloses a wireless IC device, characterized by comprising: a wireless IC chip; a power supply circuit board connected to the wireless IC chip and provided with a power supply circuit, the power supply circuit including a resonant circuit having a predetermined resonant frequency; and a radiating plate attached to or near the power supply circuit board, which radiates a transmit signal and / or receive signal supplied from the power supply circuit to the power supply circuit; wherein the frequency of the transmit signal and / or receive signal is substantially equivalent to the resonant frequency of the resonant circuit.

[0003] Patent document 2 (Japanese Patent Application Publication No. 2011-097586) discloses an assembly that is an assembly of an article body and an electronic tag. The electronic tag is a tag having an electronic device that stores inherent data of the article and an antenna connected to the electronic device and used to transmit the stored data to a remote reading device. A part of the article is at least partially composed of a material component containing rubber. The electronic device and the antenna are mounted on a part of the article and have an external contact unit. The antenna is flexible and is at least partially composed of a flexible conductive material. The flexible conductive material is an assembly that at least partially contains conductive rubber.

[0004] Patent document 3 (Japanese Patent Application Publication No. 2017-132291) discloses an RFID tag-embedded tire. In the RFID tag-embedded tire equipped with an RFID chip and an antenna, the antenna consists of a first antenna connected to the RFID chip and a second antenna disposed outside the first antenna and coupled to the electromagnetic field of the first antenna. The RFID chip and the first antenna are fixed to a first fixing member, and the RFID tag is disposed on the radially outer side of the tire carcass ply, so that the second antenna is coupled to the conductive carcass ply cords constituting the carcass ply with an electromagnetic field.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Re-evaluation No. 2007-083574

[0008] Patent Document 2: Japanese Patent Application Publication No. 2011-097586

[0009] Patent Document 3: Japanese Patent Application Publication No. 2017-132291 Summary of the Invention

[0010] The problem that the invention aims to solve

[0011] Passive radio frequency identification transponders (hereinafter also called RFID tags) are non-contact information recording and reproduction devices capable of writing or reading information using radio waves. By installing the transponder on the tire and writing or reading tire-related information to the transponder, tire management is possible.

[0012] For example, in tires used in automobiles and other vehicles, it is necessary to understand the inherent information of each tire, such as its specifications, manufacturing history, and usage history, in the manufacturing management, distribution management, maintenance management during tire use, and after the end of its service life, including the manufacturing management of tires with worn treads that have been retreaded, as well as their maintenance management.

[0013] However, the strain generated within the tires during vehicle operation is concentrated at the interface between the rubber covering electronic components such as RFID tags and adjacent components. As a result, cracks may occur between the electronic components and adjacent components, causing problems.

[0014] On the other hand, from the perspective of improving durability, if a large amount of carbon black is added to the rubber covering the electronic components, it may sometimes affect the communication performance of the RFID tags installed on the tires and prevent them from communicating smoothly.

[0015] Previously, most RFID tags embedded and used in rubber products such as car tires used half-wavelength dipole antennas. However, when embedding dipole antenna RFID tags in rubber products containing carbon black, a resistance of tens to hundreds of kΩ is connected between the two power supply points of the RFID tag. This resistance exists between the two antenna elements of the half-wavelength dipole antenna, thus significantly affecting the antenna impedance and effective electrical length.

[0016] In addition, in a typical dipole antenna, since the RF chip is located in the center of the dipole antenna, when the tire extends or retracts significantly, there is a problem that the junction between the RF chip and the two antenna lines connected to the two ends of the RF chip may break, making communication impossible.

[0017] In addition, when RFID tags with dipole antennas are directly embedded in tires, the shape and electrical length of the dipole antennas change during tire manufacturing processes such as vulcanization, and the communication range of the RFID tags deteriorates at the communication frequency.

[0018] The wireless IC device of the invention described in Patent Document 1 is configured such that a power supply circuit including a resonant circuit having a specified resonant frequency is arranged between the wireless IC chip and the radiating plate, such that the frequency of the transmitted signal and / or received signal is substantially equivalent to the resonant frequency of the resonant circuit.

[0019] However, due to electromagnetic field coupling and / or capacitive coupling between the radiating plate and the power supply circuit (first embodiment, see reference 1)... Figures 1 to 7 Therefore, the following problems exist: the signal source impedance of the radiation plate is high. When the wireless IC device is embedded in a rubber product containing carbon black, the communication distance and other characteristics of the wireless IC device are easily affected by the impedance of the carbon black and the dielectric constant of the rubber product.

[0020] The assembly of the tire rubber or other article body and the electronic tag described in Patent Document 2 is suitable for mechanical assembly into the article by using at least part of a flexible conductive material containing conductive rubber in the antenna.

[0021] However, when electronic tags are embedded in rubber products containing carbon black, the communication range and other characteristics of wireless IC devices are easily affected by the impedance of carbon black and the dielectric constant of the rubber products. In addition, when the antenna is made of conductive rubber, there is a problem that the resistivity is higher compared with metal antennas.

[0022] The RFID tag-embedded tire described in Patent Document 3 is an RFID tag-embedded tire in which a first antenna connected to an RFID chip and a second antenna disposed outside the first antenna are electromagnetically coupled, and the second antenna is electromagnetically coupled to the conductive tire carcass ply cords.

[0023] However, due to the electromagnetic field coupling between the first and second antennas, and the high signal source impedance of the second antenna, when RFID tags are embedded in rubber products containing carbon black, the communication distance and other characteristics of the RFID tags are easily affected by the impedance of the carbon black and the dielectric constant of the rubber products.

[0024] The main objective of this invention is to provide a coil for RF tags that is not affected by the carbon black contained in the tire or the dielectric constant of the tire, even when used by pasting or embedding it in the tire, and can be configured into an RFID tag with excellent communication characteristics.

[0025] Technical solutions to the problem (1)

[0027] One aspect of RF tag coils is used in RFID tags having an RF chip and a substrate with a patterned coil connected to the RF chip. The RF chip and patterned coil can be mounted on the surface of the substrate or embedded inside the substrate.

[0028] The substrate and coil are housed in a housing. The coil surrounds the substrate. A first end of the coil extends from the substrate to form a first element of the antenna. A second end of the coil extends from the substrate to form a second element of the antenna. The first element and the second element are parallel, and the extension length of the first element is longer than that of the second element. The coil and the patterned coil form a coupling transformer. The number of turns of the coil is smaller than that of the patterned coil.

[0029] In this case, by making the number of turns of the coil on the primary side of the coupling transformer smaller than the number of turns of the patterned coil on the secondary side, the input impedance of the coil connected to the first and second elements is set to a low impedance, and the secondary side is converted to a high impedance, which can be adapted to the input impedance of the RF chip.

[0030] In addition, the guide portion provided on the housing can stabilize the positional relationship between the substrate and the coil.

[0031] When the coil of the RFID tag constituting the present invention is installed on a rubber product such as a tire, it is electrically connected to the rubber product, which has a resistive impedance, via a second element. The rubber product then functions as the ground for the RFID tag, enabling communication with high sensitivity. Therefore, when installed on a rubber product such as a tire, an RFID tag with excellent communication characteristics can be formed.

[0032] Furthermore, since the RFID tag constructed from the coil of the present invention does not require the primary side of the coupling transformer to be disposed on the upper surface of the substrate, the size of the substrate can be effectively reduced. Therefore, even when installed on rubber products such as deformed tires, it is not easily damaged or peeled off, and can be formed into an RFID tag with excellent durability.

[0033] The coil of this invention can be an air-core coil. (2)

[0035] In the second invention, in one aspect of the coil, the coil and the first and second elements at the ends of the coil can also be formed by bending a wire.

[0036] In this case, since there is no need to use welding or other methods to connect the coil to the first and second components, the manufacturing process is simple and the electrical connection is highly reliable. (3)

[0038] In the coil of the third invention, or in one aspect of the coil of the second invention, the outer casing has a guide portion for maintaining the shape of the coil and a receiving portion for receiving the substrate, and the axis of the patterned coil and the axis of the coil may also be consistent.

[0039] In this case, since the coil and the substrate are fixed to the housing, the central axis of the patterned coil can be accurately aligned with the central axis of the coil. Therefore, the efficiency of the coupling transformer can be improved. (4)

[0041] In the coil of the fourth invention, in one aspect of the coil of the third invention, when the wavelength of the radio wave in the communication frequency of the RFID tag is set to λ, the electrical length of the first element can be λ / 4, λ / 2, 3λ / 4 or 5λ / 8.

[0042] In this case, by setting the electrical length of the first element to λ / 4, λ / 2, 3λ / 4, or 5λ / 8, the resonant frequency of the first element can be made to match the communication frequency of the RFID tag, thereby extending the communication distance of the RFID tag. (5)

[0044] The coil of the fifth invention, in one aspect of the coils of the fourth invention, wherein the coil and the substrate are encapsulated in a housing by resin.

[0045] In this case, it is possible to prevent the primary side of the coupling transformer from shifting relative to the substrate during embedding. Furthermore, since the RF chip can be sealed with resin, it is possible to mount it on the patterned coil as a bare chip without an encapsulated RF chip.

[0046] (A)

[0047] In the coil of the first invention, and in the coil of the second invention, one of the wires can also be a braided conductor.

[0048] In this case, the first element and the second element are formed by braided wires (braided copper wires, braided conductors) of conductors, so that even if the tire deforms significantly, not all the braided wires will break at once, thus maintaining communication and providing excellent durability.

[0049] (B)

[0050] In the coil of the B invention, and in the coils of one to the fifth invention, the coil may also be attached to the inside of the tire or embedded in the rubber of the tire.

[0051] In this case, various data for maintaining and managing the tire can be managed by RFID tags that are affixed to the inside of the tire or embedded in the rubber of the tire.

[0052] (C)

[0053] The RFID tag of the Cth invention is built into the tire, and the RFID tag with a coil of the fifth invention can also be affixed to the inside of the tire or embedded in the tire rubber.

[0054] In this case, by communicating with RFID tags affixed to the inside of the tire or embedded in the rubber of the tire, it is possible to write or read the inherent information of each tire, such as its specifications, manufacturing history, and usage history, for maintaining and managing the tire. Attached Figure Description

[0055] Figure 1 This is a schematic front view of the RFID tag as viewed from the first side of the substrate.

[0056] Figure 2 This is a schematic magnified front view when viewed from the first side of the substrate.

[0057] Figure 3 This is a schematic magnified rear view when viewed from the second side of the substrate.

[0058] Figure 4 It is by Figure 3 A schematic cross-sectional view of the substrate cut by the a-a' line.

[0059] Figure 5 This is the equivalent circuit diagram of an RFID tag.

[0060] Figure 6 This is a schematic diagram showing the connection between the RF chip and the secondary side of the coupling transformer when the RF chip is positioned at the first angle.

[0061] Figure 7 This is a schematic diagram showing the connection between the RF chip and the secondary side of the coupling transformer when the RF chip is positioned at a second angle orthogonal to the first angle.

[0062] Figure 8 This is a schematic top view of an RFID tag bonded to a butyl rubber sheet, viewed from the second side of the substrate.

[0063] Figure 9 This is a schematic cross-sectional view of the RFID tag being wrapped in rubber, showing the state of the RFID tag being sandwiched between a butyl rubber sheet and a second rubber sheet, viewed from the side.

[0064] Figure 10 This is a diagram illustrating an example of the frequency characteristics of an RFID tag's communication range, measured by attaching a rubber-coated RFID tag to the inside of a tire.

[0065] Figure 11 This is a schematic cross-sectional view showing the state of rubber-coated RFID tags affixed to the inside of a tire.

[0066] Figure 12 This is a schematic diagram illustrating an example of a manufacturing line for rubber-coated RFID tags.

[0067] Figure 13 This is a partial schematic diagram of a manufacturing line that uses RFID tags in a tapping state to manufacture rubber-coated RFID tags.

[0068] Figure 14 It means Figure 4 Schematic cross-sectional views of other examples.

[0069] Figure 15 This is a schematic diagram illustrating other examples of a manufacturing line for rubber-coated RFID tags.

[0070] Figure 16 This is a diagram illustrating the frequency and communication distance when RFID tags are installed on tires.

[0071] Figure 17 This is a schematic perspective view of an RFID tag equipped with a coil according to the third embodiment.

[0072] Figure 18 (a) A schematic perspective view of a coil having a first element and a second element at its ends, and a substrate, in the third embodiment. Figure 18 (b) is a schematic perspective view of an RFID tag having a coil of the third embodiment, a patterned coil mounted on a substrate, and an RF chip.

[0073] Figure 19 It is a schematic perspective view of an RFID tag having a coil of the third embodiment, a coil housed in a housing, and a substrate.

[0074] Figure 20 This is a schematic perspective view showing the housing and guide portion of an RFID tag equipped with a coil according to the third embodiment.

[0075] Figure 21 (a) is a schematic perspective view of an RFID tag with a coil of the first modified example. Figure 21 (b) is a schematic top view of an RFID tag with a coil of the first variant.

[0076] Figure 22 (a) is a schematic perspective view of an RFID tag with a coil of the second variation. Figure 21 (b) is a schematic top view of an RFID tag with a coil of the second variation. Detailed Implementation

[0077] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the following description, the same components are labeled with the same reference numerals. Furthermore, where the same reference numerals are used, their names and functions are also the same. Therefore, detailed descriptions will not be repeated.

[0078] It should be noted that the invention described in the claims of the patent is equivalent to the coil of the third embodiment described below.

[0079] (First Implementation)

[0080] Figure 1 This is a schematic front view of the RFID tag 100, viewed from the first side 91 of the substrate 90, showing the RFID tag 100 having a first element 50, a second element 60 constituting an antenna, and the substrate 90. Figure 2 This is a schematic enlarged front view taken from the first side 91 of the substrate 90. Figure 3 This is a schematic magnified rear view when viewed from the second side 92 of the substrate 90. Figure 4 It is by Figure 3 A schematic cross-sectional view showing the substrate after being cut 90 degrees along line a-a'. Additionally, Figure 5 This is the equivalent circuit diagram of RFID tag 100.

[0081] like Figures 1 to 4 As shown, a track-shaped groove 65 is formed on the first surface 91 of the rectangular substrate 90 (see reference). Figure 4 Furthermore, a second element 60 formed of a rectangular conductor is provided on the first surface 91 of the substrate 90. A plurality of through holes 70 are provided at the bottom of the groove 65. The plurality of through holes 70 can be provided at appropriate intervals. In this embodiment, five through holes 70 are provided, preferably two or more, more preferably four or more. A first element 50 formed of braided conductor wire is disposed within the groove 65.

[0082] Here, the arrangement of the first element 50 in the groove 65 means that the first element 50 is electrically connected to the through hole 70. For example, the first element 50 with deformability can be pressed into the groove 65, or the first element 50 can be arranged in the groove 65 and electrically connected to the through hole 70 by allowing a portion of the butyl rubber sheet 120 to enter the groove 65, or it can be in a capacitive coupling state.

[0083] A first element 50 is disposed in the groove 65, with one end and the other end of the first element 50 extending outward from the substrate 90. In this embodiment, the extension length of one end is approximately 1 / 10 of the total length of the first element 50, and the extension length of the other end is approximately 4 / 5 of the total length of the first element 50. The extension direction of the other end of the first element 50 is substantially along the length direction of the substrate 90.

[0084] (First element 50)

[0085] The braided wire used in the first element 50 can be any metal wire (including mesh wire) made of braided copper wire, iron wire, brass wire, etc. Alternatively, other metal raw materials with flexibility and conductivity (e.g., strips, ribbons, etc.) can also be used.

[0086] Because the braided yarn is composed of an assembly of multiple metal wires, butyl rubber sheet 120 (refer to...) Figure 9 The components of the RFID tag 100 permeate into the interior of the braided thread, which is integrated with the butyl rubber sheet 120, reliably preventing the RFID tag 100 from being ejected from the butyl rubber sheet 120 and the tire 160. Figure 11 (Refer to) stripping.

[0087] Furthermore, by forming the first element 50 from braided threads, the first element 50 can be bent, twisted, deformed, etc. Therefore, when the tire 160 deforms or vibrates, the first element 50 follows the deformation and vibration of the tire 160, thus suppressing the first element 50 from breaking off, and also suppressing the peeling of the connection portion with the substrate 90.

[0088] The second element 60 can be formed from a metal pattern, metal foil, metal plate, etc. To reduce impedance with the tire 160, the surface of the second element 60 is exposed from the surface of the substrate 90. The size of the second element 60 is not limited to this; in this embodiment, it is a rectangle approximately 5.5 mm × 2.5 mm. The shape of the second element 60 does not necessarily have to be rectangular; for example, it can be circular. However, to reduce the connection impedance between the second element 60 and the tire 160, it is preferable that the area of ​​the second element 60 is 3 mm². 2 The above, preferably 5mm 2 above.

[0089] Next, an RF chip 10 and a coupling transformer 20 are disposed on the second surface 92 of the substrate 90. The two terminals of the primary side 30 of the coupling transformer 20 are connected to the first element 50 and the second element 60 respectively via a through hole 70 at the bottom of the slot 65 and a through hole 80 on the substrate 90. Furthermore, the two terminals of the secondary side 40 of the coupling transformer 20 are connected to the terminals of the RF chip 10 via wire bonding.

[0090] It should be noted that in this embodiment, the case where the primary side 30 and the secondary side 40 of the coupling transformer 20 are both provided on the second surface 92 of the substrate 90 is described, but it is not limited to this. The primary side 30 and the secondary side 40 may be provided on the other surface of the substrate 90 to form the coupling transformer 20, or multiple substrates 90 may be stacked and provided on different layers.

[0091] The RF chip 10 is bonded to the surface of the secondary side 40 of the coupling transformer 20 or the substrate 90 using an adhesive such as an epoxy-based die-casting material. Furthermore, the secondary side 40 of the coupling transformer 20 and the RF chip 10 are sealed with a resin layer.

[0092] As the resin layer, insulating resins such as epoxy resin, acrylic resin (resins mainly composed of acrylic resin and its derivatives), and polyurethane resin can be used.

[0093] The RF chip 10 can use commercially available products, and it is particularly preferred to use a chip that is resistant to a sulfidation temperature of around 120°C.

[0094] It should be noted that, as Figure 9 As shown, the RFID tag 100 of this embodiment is typically used by attaching or embedding it in a tire 160 in a state where it is sandwiched between a first rubber sheet 120 and a second rubber sheet 130 made of butyl rubber.

[0095] The specific structure is as follows.

[0096] An RFID tag 100 is disposed between a first rubber sheet 120 and a second rubber sheet 130. A rubber-coated RFID tag (hereinafter also referred to as a rubber-coated RFID tag 150) is formed by pressing together a laminate of the first rubber sheet 120, the RFID tag 100, and the second rubber sheet 130 in sequence. Here, the RFID tag 100 is sandwiched between the first rubber sheet 120 and the second rubber sheet 130 such that the first surface 91 of the first element 50 and the substrate 90 is disposed on the side of the first rubber sheet 120, and the second surface 92 of the first element 50 and the substrate 90 is disposed on the side of the second rubber sheet 130. In the resulting rubber-coated RFID tag 150, the first surface 91 of the substrate 90 is covered by the first rubber sheet 120, and the second surface 92 is covered by the second rubber sheet 130.

[0097] (First rubber sheet 120)

[0098] The first rubber sheet 120 used in this invention is formed by forming a rubber composition containing butyl rubber into a sheet. For example, the first rubber sheet 120 having a predetermined size is formed into a long strip by calendering the rubber composition with rollers or the like, and the strip is cut into a predetermined shape and size, thereby making it easy to obtain.

[0099] To improve adhesion and breathability, the butyl rubber content in the first rubber sheet 120 is preferably 50% by weight or more, more preferably 70% by weight or more and 95% by weight or less. The rubber composition may contain halogenated butyl rubber, diene rubber, epichlorohydrin rubber, etc.

[0100] Examples of diene-based rubbers include natural rubber (NR), isoprene rubber (IR), styrene-butadiene copolymer rubber (SBR), acrylonitrile-butadiene rubber (NBR), and chloroprene rubber (CR). These diene-based rubbers can be used individually or in combination of two or more.

[0101] In the first rubber sheet 120 described above, compounding agents commonly used in the rubber industry may also be appropriately added according to the purpose, such as reinforcing fillers, softeners, anti-aging agents, anti-scorching agents, zinc oxide, stearic acid, etc. These compounding agents are preferably commercially available products. The thickness of the first rubber sheet 120 is arbitrary, but can be set to a range of 5 μm or more and 500 μm or less, and is particularly preferred to be 10 μm or more and 200 μm or less.

[0102] The first rubber sheet 120 is typically an uncured rubber sheet, which, due to its excellent adhesion, can be used, for example, as a liner component for a pneumatic tire 160.

[0103] (Second rubber sheet 130)

[0104] The second rubber sheet 130 is formed into a sheet by forming a second rubber composition containing rubber. For example, the second rubber sheet 130 having a predetermined size can be easily obtained by calendering the second rubber composition into a long strip using rollers or the like, and then cutting the strip into a predetermined shape and size.

[0105] As a type of rubber, one or more types can be appropriately selected from commonly used natural rubber and / or various synthetic rubbers.

[0106] As synthetic rubbers, examples include nitrile rubber (NBR), butadiene rubber (BR), isoprene rubber (IR), styrene-butadiene rubber (SBR), butyl rubber (IIR), halogenated IIR, ethylene propylene diene rubber (EPDM), chloroprene rubber (CR), ethylene propylene rubber, and acrylonitrile-butadiene rubber (NBR).

[0107] The second rubber composition can use the first rubber composition described above, but preferably contains a crosslinking agent. As such a crosslinking agent, any type can be used, as long as it is a crosslinking agent commonly used in the crosslinking of rubber compositions. Examples include sulfur, organic peroxides, and organic sulfur compounds. The amount of crosslinking agent added relative to 100 parts by weight of the rubber component is typically 0.1 parts by weight or more and 10 parts by weight or less, preferably 1 part by weight or more and 5 parts by weight or less.

[0108] In addition, various rubber additives commonly used in the rubber industry, such as vulcanization accelerators, fillers, oils, and anti-aging agents, can be appropriately incorporated into the rubber composition.

[0109] Examples of vulcanization accelerators include stearic acid, N-cyclohexyl-2-benzothiazolyl sulfenamide (CZ), N,N'-dicyclohexyl-2-benzothiazolyl sulfenamide (DZ), and di-2-benzothiazolyl disulfide (DM). They can be used alone or in combination of two or more. The amount of vulcanization accelerator incorporated relative to 100 parts by weight of rubber component is typically 0.1 parts by weight or more and 10 parts by weight or less, preferably 1 part by weight or more and 3 parts by weight or less.

[0110] Examples of fillers include carbon black, silica, calcium carbonate, calcium sulfate, talc, clay, mica, zinc oxide, barium sulfate, and titanium dioxide. One type may be used alone, or two or more may be used in combination. The amount of filler incorporated relative to 100 parts by weight of the rubber component is typically 10 parts by weight or more and 200 parts by weight or less, preferably 30 parts by weight or more and 150 parts by weight or less.

[0111] As the oil, various types of oils can be used, such as paraffinic, cycloalkanes, and aromatic processing oils; ethylene-α-olefin copolymers; mineral oils such as paraffin and liquid paraffin; and vegetable oils such as castor oil, cottonseed oil, linseed oil, rapeseed oil, soybean oil, palm oil, coconut oil, and peanut oil. One or more of these can be used alone or in combination. The amount of oil in the formulation is typically 0.1 parts by weight or more and 100 parts by weight or less relative to 100 parts by weight of the rubber component, preferably 1 part by weight or more and 50 parts by weight or less.

[0112] Examples of anti-aging agents include, for example, naphthylamines such as phenyl-α-naphthylamine; diphenylamines such as octyl diphenylamine; p-p-phenylenediamines such as N-isopropyl-N'-phenyl-p-phenylenediamine, N-(1,3-dimethylbutyl)-N'-phenyl-p-p-phenylenediamine, and N,N'-di-2-naphthyl-p-p-phenylenediamine; quinoline-based agents such as polymers of 2,2,4-trimethyl-1,2-dihydroquinoline; and phenolic anti-aging agents such as 2,6-di-tert-butyl-4-methylphenol, styrylated phenol, and tetra-[methylene-3-(3',5'-di-tert-butyl-4'-hydroxyphenyl)propionate]methane. The amount of anti-aging agent incorporated relative to 100 parts by weight of the rubber component is typically 0.1 parts by weight or more and 20 parts by weight or less, preferably 0.5 parts by weight or more and 10 parts by weight or less.

[0113] These additives can be combined with the rubber composition of the first rubber sheet 120.

[0114] The thickness of the second rubber sheet 130 is arbitrary, but can be in the range of 5 μm or more and 500 μm or less, and is particularly preferably 10 μm or more and 200 μm or less.

[0115] The second rubber sheet 130 contains a vulcanizing agent, and in the case of an unvulcanized rubber sheet that is cured by heat, in order to produce a vulcanized sheet by heat, the second rubber sheet 130 is subjected to a heat / vulcanization treatment at a temperature typically above 120°C, preferably above 125°C and below 200°C, more preferably above 130°C and below 180°C. A vulcanized sheet is obtained by this heating. This heat / vulcanization treatment is performed during the vulcanization of a typical tire.

[0116] Thus, when the second rubber sheet 130 is heated / vulcanized during the vulcanization of the tire, the heating / vulcanization process can be performed while the side of the first rubber sheet 120 covering the RFID tag 150 is bonded to the inner surface of the tire 160.

[0117] (RFID tag built into tire 500)

[0118] Figure 11 This is a schematic cross-sectional view showing the state in which the rubber-coated RFID tag 150 is affixed to the inside of the tire 160, indicating that the RFID tag 150 (described later) is installed inside the tire 500. The rubber-coated RFID tag 150 can be affixed to the inside of the tire 160 or embedded in the rubber of the tire 160.

[0119] In this embodiment, a rubber-coated RFID tag 150 is mounted on the tire 160, but an RFID tag 100 can also be mounted on the tire 160. The tire 160 is typically a tire containing carbon black, which affects the tire's impedance.

[0120] The RFID tag 100 or rubber-coated RFID tag 150 is mounted on the tire 160, thereby electrically connecting the second element 60 to the tire 160. As a result, the tire 160 functions as a ground for the RFID tag 100. Therefore, the RFID tag 100 or rubber-coated RFID tag 150 of the present invention can communicate with high sensitivity even when mounted on the tire 160. It should be noted that the connection between the second element 60 and the tire 160 can be either a capacitive connection or a direct connection.

[0121] (Tire 160)

[0122] The tire 160 used in this invention is not particularly limited, and is generally a rubber-made air tire, typically a tire 160 containing carbon black. An RFID tag 100 is embedded or affixed to the inner circumferential surface of the tire 160. The vehicle on which the tire 160 is installed is also not limited, and examples include automobiles, motorcycles, bicycles, construction machinery, and aircraft.

[0123] exist Figure 11 In the tire 160, there are a rim 161, a sidewall 166 and a tread 165, and a bead wire 162, a carcass 163 and a buffer layer cord 164 embedded therein.

[0124] Tire 160 contains rubber components (natural rubber, synthetic rubber), carbon black, vulcanizing agents, fillers, etc. Generally, relative to 100 parts by weight of rubber, the carbon black content is 40 parts by weight or more and 60 parts by weight or less, especially 45 parts by weight or more and 55 parts by weight or less.

[0125] The RFID tag 100 is adhered to the inner circumferential surface of the tire 160 using a first rubber sheet 120. The first rubber sheet 120 has adhesive properties, and furthermore, it can mix with exudates (such as grease) seeping from the inside of the tire 160. As a result, the RFID tag 100 can be adhered to the inner surface of the tire 160 for a long period.

[0126] The RFID tag 100 can be affixed to the inner circumferential surface of the portion of the tire 160 that has the tread pattern, or it can be affixed to the inner circumferential surface of the tire bead portion of the tire 160.

[0127] Next, refer to Figure 5The equivalent circuit diagram of the RFID tag 100 is shown below. For example, during reception, the radio waves received by the first element 50 and the second element 60 are transmitted to the RF chip 10 via the coupling transformer 20. In this case, the impedance of the RF chip 10 is from a few kΩ to about 10 kΩ, while the impedance between the first element 50 and the second element 60 is as small as 100 Ω.

[0128] The impedance between the first element 50 and the second element 60 is relatively small. Besides the impedance of the antenna itself, the resistive component of the carbon black contained in the second rubber sheet 130 and the surrounding tire 160 has a significant impact. The vulcanized rubber tire 160 has a resistivity of around tens of kΩ·cm, depending on the type of tire. On the other hand, the impedance of the RF chip 10 is in the range of kΩ to 10kΩ.

[0129] Therefore, when the RFID tag 100 of this embodiment is embedded in the vulcanized rubber tire 160, if the terminals of the RF chip 10 are directly connected to the first element 50 and the second element 60, the received radio waves cannot be efficiently guided to the RF chip 10.

[0130] When the RF chip 10 with input impedance Z is connected to the first element 50 and the second element 60 via a coupling transformer 20 whose turns ratio n is the number of turns of the secondary side 40 divided by the number of turns of the primary side 30, the impedance of the primary side 30 of the coupling transformer 20 becomes Z / n. 2 .

[0131] Therefore, in the RFID tag 100 of the first embodiment, by adjusting the ratio of the number of coil turns on the secondary side 40 of the coupling transformer 20 to the number of coil turns on the primary side 30, the primary side 30 of the coupling transformer 20 is input with low impedance, and the secondary side 40 is transformed to high impedance, thereby adapting to the input impedance of the RF chip 10.

[0132] However, in order to increase the number of coil turns on the secondary side 40, there are limitations such as the area of ​​the coupling transformer 20. The ratio of the number of coil turns on the secondary side 40 to that on the primary side 30 is preferably adjusted according to the specifications of the IC chip, or the material of the tire, the content of carbon black, etc.

[0133] In this embodiment, the first element 50 extends from the substrate 90 in one direction, and the antenna of the RFID tag 100 operates similarly to a monopole antenna with the second element 60 as a ground plane and the first element 50 as an antenna line.

[0134] Therefore, by setting the wavelength in the communication frequency of the RFID tag 100 to λ and setting the electrical length of the first element 50 to λ / 4 or λ / 2, the resonant frequency of the first element 50 can be made to match the communication frequency of the RFID tag 100, which is therefore preferred.

[0135] In addition, when the RFID tag 100 is affixed to or embedded in the vulcanized rubber tire 160, it is electrically connected to the vulcanized rubber tire 160 via the second element 60, thereby further strengthening the ground plane.

[0136] In addition, in this embodiment, one end of the first element 50 formed by the braided wire of the conductor is disposed (e.g., fitted) in a groove 65 formed on the substrate 90, and the other end extends from the substrate 90.

[0137] In conventional RFID tags with dipole antennas, antenna elements with an electrical length of λ / 4 are connected to both ends of a substrate housing an RF chip. However, in this structure, when the tire extends or retracts, applying opposite stresses to the two antenna elements, the connection between the antenna elements and the substrate may break.

[0138] In contrast, as in this embodiment, it has the following advantages: when one end of the first element 50 is disposed near the substrate 90 and the other end is left open, the connection between the end of the first element 50 and the substrate 90 is not easily damaged.

[0139] Furthermore, in this embodiment, by inserting the first element 50 formed of braided wire into the groove 65 formed on the substrate 90 and pressing it against the through hole 70 to make a conductive connection, the connection between the first element 50 and the substrate 90 is stronger than the expansion and contraction of the tire 160 compared to the case where welding is used, and the positional relationship between the first element 50 and the substrate 90 is also stable.

[0140] (Manufacturing of Rubber-Coated RFID Tag 150)

[0141] Next, the manufacturing apparatus and manufacturing method of the rubber-coated RFID tag 150 of the present invention will be described.

[0142] Figure 12 This is a schematic diagram illustrating an example of a manufacturing line for rubber-coated RFID tags 150.

[0143] exist Figure 12 In this design, the braiding roller 200 supplies braided yarn 205, which forms the first element 50, and the butyl rubber roller 210 supplies the first rubber sheet 120, which is in the form of a strip and is coiled. Braided yarn 205 is disposed on the first rubber sheet 120 fed from the butyl rubber roller 210. The braided yarn 205 disposed on the first rubber sheet 120 is bonded to the first rubber sheet 120.

[0144] An idler roller 220 and a label stacker 230 are provided on the supply side of the butyl rubber roller 210. The label stacker 230 is configured such that multiple substrates 90 are arranged vertically, and a substrate 90 can be sequentially pasted onto a first rubber sheet 120. The substrate 90 and the braided wire 205 are positioned such that a recessed groove 65 formed on the underside of the substrate 90 is arranged along the supply direction, and a braided wire 205 is inserted into the recessed groove 65.

[0145] In this embodiment, the substrate 90 configured in the tag stacker 230 is provided with a second element 60 on the first side 91 and an RF chip 10 and a coupling transformer 20 on the second side 92 of the substrate 90.

[0146] That is, the substrate 90 filled in the tag stacker 230 is a substrate that does not contain the first element 50 in the RFID tag 100 described above. By using the manufacturing method of the rubber-coated RFID tag 150 described herein, a rubber-coated RFID tag 150 that also has the first element 50 is manufactured.

[0147] It should be noted that the method of providing the second element 60 and the coupling transformer 20 on the substrate 90 can be achieved using known methods such as etching. Furthermore, the method of providing the RF chip 10 on the substrate 90 can be achieved using known methods such as wire bonding.

[0148] Figure 12 The second rubber roller 240 is a roller for supplying vulcanized rubber sheet 130 to the substrate 90 disposed on the first rubber sheet 120. The idler rollers 250 and 260 are idler rollers for pressing the laminate containing the first rubber sheet 120, the substrate 90 and the vulcanized rubber sheet 130.

[0149] By pressing the laminate containing the first rubber sheet 120, the substrate 90, and the vulcanized rubber sheet 130 in sequence with idler wheels 250 and 260, the butyl rubber sheet 120, which is part of the first rubber sheet 120, enters the recessed groove 65, and the braided thread disposed in the recessed groove 65 is reliably held in the recessed groove 65.

[0150] A portion of the butyl rubber sheet 120 and the second rubber sheet 130 extends outward from the periphery of the substrate 90, and thus the peripheries of the butyl rubber sheet 120 and the second rubber sheet 130 are bonded to each other by pressure contact.

[0151] Therefore, the components (RF chip 10, coupling transformer 20, second component 60) disposed on the substrate 90, the first surface 91 and the second surface 92 of the substrate 90, and the first component 50 (braided wire 205) are protected by the butyl rubber sheet 120 and the second rubber sheet 130.

[0152] Figure 12 In the process, cutter 270 and cutter 280 cut the laminate composed of first rubber sheet 120, braided thread 205 and vulcanized rubber sheet 130 at a set position to obtain a set size.

[0153] Using the manufacturing apparatus described above, the rubber-coated RFID tag 150 of the present invention can be manufactured as follows.

[0154] A braided thread 205 fed from a braided thread roller 200 is overlapped on a first rubber sheet 120 fed from a butyl rubber roller 210. At the label stacker 230, a substrate 90 is positioned at a predetermined location between the first rubber sheet 120 and the braided thread 205, and the braided thread 205 is placed within a groove 65 of the substrate 90. At this time, the braided thread is pressed into the groove 65 by applying pressure to the substrate 90 towards the idler wheel 220.

[0155] Next, a second rubber sheet 130 fed from the second rubber roller 240 is disposed on a substrate 90 attached to the first rubber sheet 120.

[0156] Next, the laminate containing the first rubber sheet 120, the substrate 90, and the second rubber sheet 130 is passed between idler rollers 250 and 260 to press the laminate together.

[0157] Next, the laminated body is cut into the specified size.

[0158] (Other manufacturing methods for rubber-coated RFID tags 150)

[0159] exist Figure 12 The manufacturing method shown employs a structure in which the substrate 90 supplied from the label stacker 230 is fed onto the butyl rubber sheet 120. However, the substrate 90 can also be fed onto the butyl rubber sheet 120 by the following method.

[0160] Figure 13 The manufacturing apparatus shown includes: a label supply roller 290, which attaches a plurality of substrates 90 to a non-stretchable strip substrate at certain intervals and winds the substrate; a first idler roller 220 and a second idler roller 310 disposed opposite to the first idler roller 220; and a take-up roller 300.

[0161] The substrate 90 is fed from the label supply roller 290 and is provided at certain intervals, so that it passes between the first idler roller 220 and the second idler roller 310, thereby transferring the substrate 90 onto the butyl rubber sheet 120.

[0162] In this manufacturing apparatus, the braided wires 205 on the first rubber sheet 120 are embedded in the grooves 65 of the substrate 90, and the braided wires 205 are disposed in the grooves 65.

[0163] then, Figure 8 This is a top view showing the state in which the RFID tag 100 is bonded to the first rubber sheet 120 in the rubber-coated RFID tag 150 manufactured by the above-described manufacturing method. Additionally, Figure 9 Indicates in Figure 8 The cross-sectional view of the rubber-coated RFID tag 150, in which the RFID tag 100, which is bonded to the first rubber sheet 120, is further covered and pressed against the second rubber sheet 130, and the RFID tag 100 is sandwiched between the first rubber sheet 120 and the second rubber sheet 130.

[0164] It should be noted that, in Figure 8 The diagram also shows the cutting of the first rubber sheet 120, the braided thread 205 (first element 50), and the second rubber sheet 130 (see reference) during manufacturing. Figure 9 The cut surface 110.

[0165] The cut surface 110 is slightly away from the end of the substrate 90, resulting in the end of the first element 50 protruding slightly from the end of the substrate 90. Therefore, even after cutting, the entire substrate 90 is reliably covered by the first rubber sheet 120 and the second rubber sheet 130, preventing exposure. It should be noted that in this embodiment, the distance between the end face of the substrate 90 and the cut surface 110 is approximately 5 mm. Preferably, the distance between the end face of the substrate 90 and the cut surface 110 is 5 mm or more.

[0166] By clamping the RFID tag 100 with the first rubber sheet 120 and the second rubber sheet 130, the first element 50 can be reliably positioned in the groove 65 and electrically connected to the through hole 70 even when the tire 160 is extending or retracting while the car is in motion, and the positional relationship between the first element 50 and the substrate 90 can be stabilized.

[0167] Figure 11 This is a schematic cross-sectional view showing the state in which the rubber-coated RFID tag 150 is affixed to the inside of the tire 160.

[0168] exist Figure 11 In the tire 160, there are a rim 161, a sidewall 166 and a tread 165, and a bead wire 162, a carcass 163 and a buffer layer cord 164 embedded therein.

[0169] The rubber-coated RFID tag 150 is attached to the inner surface of the tire 160 in a radial direction with the first element 50 centered on the tire's axis of rotation. The rubber-coated RFID tag 150 is attached to the inner surface of the tire 160 such that the side of the first rubber sheet 120 of the rubber-coated RFID tag 150 contacts the inner surface of the tire.

[0170] Therefore, the RFID tag 100 is adhered to the inner surface of the tire by the adhesive properties of the butyl rubber sheet 120. In addition, even when the butyl rubber sheet 120 comes into contact with exudate from the inside of the tire, the butyl rubber sheet 120 can mix with the exudate, thus enabling the RFID tag 100 to remain adhered to the inner circumferential surface of the tire for a long period of time.

[0171] It should be noted that the method of fixing the rubber-coated RFID tag 150 to the tire 160 is not limited to the method described above, and it can be pasted or embedded in any part of the tire 160. For example, the rubber-coated RFID tag 150 can be pasted on the inner circumferential surface of the part of the tire with the tread pattern, or it can be pasted on the inner circumferential surface of the tire bead.

[0172] Figure 10 This is a graph showing the frequency characteristics of the communication range of the RFID tag 100, measured by attaching the rubber-coated RFID tag 150 to the inside of the tire 160.

[0173] In RFID tags embedded in tires 160, to avoid fluctuations in the antenna's frequency characteristics caused by the carbon black contained in the tire 160, the path from the RF chip to the antenna is sometimes made to have a sharp resonant characteristic. However, generally speaking, in RFID tags, the communication frequencies differ between the EU (communication frequency 860MHz) and Japan (communication frequency 920MHz). Therefore, in RFID tags that make the path from the RF chip to the antenna have a sharp resonant characteristic, different RFID tags need to be prepared for the EU and for Japan.

[0174] In contrast, in the rubber-coated RFID tag 150 of the present invention, coupling transformers 20 with different numbers of coil turns are provided between the RF chip 10 and the first element 50 and the second element 60 to reduce the impedance of the primary side 30 and eliminate the influence of carbon black contained in the tire rubber. Furthermore, this enables the tag to... Figure 10 The RFID tag 100 shown communicates with a wide range of frequencies, including those of the EU and Japan.

[0175] Furthermore, in the rubber-coated RFID tag 150 of the present invention, by measuring the RFID tag 100 with the first rubber sheet 120 and the second rubber sheet 130 sandwiched in the state, it is advantageous to be able to confirm the communication characteristics of the RFID tag 100 when it is affixed to the tire 160 or embedded in the tire 160.

[0176] (Second Implementation)

[0177] Next, in Figure 6 as well as Figure 7 Two examples of the connection between the secondary side 40 of the coupling transformer 20 and the RF chip 10 in the second embodiment are shown.

[0178] In the second embodiment of the RFID tag 100, only the method of mounting the RF chip 10 onto the substrate 90 and the method of connecting the RF chip 10 to the secondary side 40 of the coupling transformer 20 are different from those in the first embodiment; the rest are the same as in the first embodiment.

[0179] The RF chip 10 in the second embodiment uses a so-called BGA package and has two bumps 87 as terminals for electrical connection. (Typically, additional bumps 87 without electrical connection are also provided for fixing the package.) One end of the secondary side 40 of the coupling transformer 20 is directly connected to the first bump 87 of the RF chip 10, and the other end is connected to the second bump 87 of the RF chip 10 via two through holes 85 and wiring 86 on the first surface 91 side.

[0180] exist Figure 6 and Figure 7 In the coupling transformer 20, the secondary side 40 has the same shape. However, the RF chip 10 has... Figure 6 In the middle of the diagram, two protrusions 87 are arranged horizontally. Figure 7 The middle position is arranged vertically in the graph, and the result is that... Figure 7 The number of turns ratio of the secondary side coil of 40 Figure 6 The number of turns of the 40 coil on the secondary side is 1 / 4 greater.

[0181] That is, by setting the RF chip 10 to a BGA package, and setting the shape of the secondary side 40 of the coupling transformer 20 to... Figure 6 or Figure 7 The shape shown allows for changing the coil turns ratio of the coupling transformer 20 simply by changing the configuration angle of the same RF chip 10 using the same substrate 90. Therefore, in the RFID tag 100 of the second embodiment, for example, when the impedance of the primary side 30 of the coupling transformer 20 is changed by changing the material of the rubber of the tire 160 that is pasted or embedded, the impedance of the primary side 30 of the coupling transformer 20 can be changed for RF chips 10 with the same input impedance by changing the configuration angle of the RF chip 10.

[0182] It should be noted that in the above example, the difference in the number of turns of the coil on the secondary side 40 of the coupling transformer 20 is 1 / 4. However, by designing the shape of the secondary side 40 of the coupling transformer 20, the difference in the number of turns of the coil can be further increased, which is easy for those skilled in the art to understand.

[0183] then, Figure 14 It means Figure 4Another example of a schematic cross-sectional view. In Figure 14 In the RFID tag 100, replacing Figure 4 The groove 65 has a protrusion (guide) 65 formed around the through hole 70 and on the first surface 91. As a result, the first element 50 can be positioned in a predetermined position.

[0184] It should be noted that the convex portion 65 can be localized or formed in a straight line.

[0185] then, Figure 15 This is a schematic diagram illustrating another example of a manufacturing line for rubber-coated RFID tags 150.

[0186] Figure 15 The manufacturing line shown is Figure 12 The difference shown is that, in Figure 12 In the manufacturing line, the first element 50 is first mounted on the first rubber sheet 120 and the butyl rubber sheet 120, but... Figure 15 In the manufacturing line, substrate 90 is configured to be with Figure 12 On the opposite side, the so-called groove 65 faces the upper surface, and then the first element 50 is disposed in the groove 65.

[0187] at last, Figure 16 This is a schematic diagram showing the frequency and communication distance when an RFID tag 100 is installed on a tire 160.

[0188] like Figure 16 As shown, two types of tires 160 (A and B) are prepared. Furthermore, the frequency and communication distance are measured in both cases: direct coupling between the RFID tag 100 through-hole 70 and the first element 50 (A1, B1) and capacitive coupling (A2, B2).

[0189] Here, capacitive coupling mainly refers to the direct connection between the braided wire of the first element 50 and the through hole 70. However, in the manufacturing process, assuming that the braided wire of the first element 50 and the through hole 70 are separated by a small distance, the first element 50 and the through hole 70 are coupled via capacitance. In this example, this state is defined as capacitive coupling.

[0190] like Figure 16 As shown, by comparing curves A1 and B1 using different types of tires 160, a slight difference was observed. Similarly, by comparing curves A2 and B2, a slight difference was observed.

[0191] In addition, after comparing Figure 16As shown in curves A1 and A2, although the communication distance of the directly coupled side is longer, the communication distance of curve A2 after capacitive coupling is more than 5m in both 860MHz and 920MHz, so it can be seen that the practicality is sufficient.

[0192] Similarly, in comparison Figure 16 As shown in curves B1 and B2, although the communication distance is longer with the directly coupled side, curve B2 with capacitive coupling shows a communication distance of more than 5m in both 860MHz and 920MHz, thus demonstrating its sufficient practicality.

[0193] (Third Implementation)

[0194] This embodiment is one of the modifications to the coil, which is part of the coupling transformer, in the RFID tag described in Japanese Patent Application 2019-222421.

[0195] Figure 17 This is a schematic perspective view of an RFID tag 100 equipped with the coil 30 of the third embodiment. Figure 18 (a) is a schematic perspective view of a coil 30 having a first element 50 and a second element 60 at its ends, and a substrate 90, according to the third embodiment. Figure 18 (b) is a schematic perspective view of an RFID tag 100 having the coil 30 of the third embodiment, a patterned coil 40 mounted on a substrate 90, and an RF chip 10. Additionally, Figure 19 This is a schematic perspective view of an RFID tag 100 with a coil 30 according to the third embodiment, the coil 30 housed in a housing 75, and a substrate 90. Figure 20 This is a schematic enlarged perspective view showing the RFID tag 100 equipped with the coil 30 of the third embodiment, the housing 76 of the outer casing 75, and the guide portion 77.

[0196] In the RFID tag 100 of the first embodiment, the primary side 30 of the coupling transformer 20 and the second element 60 are respectively formed on the surface of the substrate 90. In contrast, in the RFID tag 100 equipped with the coil 30 of the third embodiment, the primary side of the coupling transformer is formed such that, when viewed from above, the wires of the coil 30 are held around the substrate 90 in the guide portion 77 of the housing 75. In the RFID tag 100 equipped with the coil 30 of the third embodiment, one end of the coil 30 extends to form a first element 50, and the other end of the coil 30 extends in the same direction as the first element 50 to form a second element 60, such that the extension length of the first element 50 is longer than the extension length of the second element 60. The first element 50 and the second element 60 are arranged substantially parallel to each other.

[0197] That is, the RFID tag 100 with the coil 30 of the third embodiment is an RFID tag 100 having a substrate 90 on which an RF chip 10 is mounted and a patterned coil 40 connected to the RF chip 10, a coil 30 that forms a coupling transformer with the patterned coil 40, and a housing 75 that houses the substrate 90 and the coil 30. Moreover, the first end 31 of the coil 30 extends from the substrate 90 to form a first element 50 of an antenna, and the second end 32 of the coil 30 extends from the substrate 90 in the same direction as the first element 50 to form a second element 60 of an antenna. The extension length of the first element 50 is longer than that of the second element 60, and the number of coil turns of the coil 30 is less than the number of coil turns of the patterned coil 40.

[0198] The extension lengths of the first element 50 and the second element 60, the number of coil turns of the coil 30, and the number of coil turns of the patterned coil 40 are preferably adjusted according to the specifications of the IC chip, the material of the tire, the content of carbon black, etc.

[0199] It should be noted that the extension lengths of the first element 50 and the second element 60 are respectively the lengths of the straight sections of the first element 50 and the second element 60.

[0200] Furthermore, the outer casing 75 has a guide portion 77 for holding the coil 30 and a receiving portion 76 for receiving the substrate 90, so that the substrate 90 and the coil 30 are fixed in such a way that the axis of the patterned coil 40 and the axis of the coil 30 are aligned by the outer casing 75. That is, within the outer casing 75, an annular groove for guiding the coil 30 is formed as the guide portion 77, and a wall piece for holding the substrate 90 is provided. It should be noted that it is further preferable that the center point of the axis of the patterned coil 40 and the center point of the axis of the coil 30 are also aligned in the axial direction.

[0201] Furthermore, in this embodiment, the substrate 90 can be mounted either in a manner similar to a printed circuit board, where the RF chip 10 and the patterned coil 40 are disposed on the surface of the substrate 90, or as... Figure 18 As shown in (b), the RF chip 10 and the patterned coil 40 are embedded inside the substrate 90. In this case, the substrate 90 is constructed by stacking multiple resin layers and the RF chip 10 and the patterned coil 40 are embedded between adjacent resin layers.

[0202] Furthermore, the patterned coil 40 in this embodiment can function as a coil constituting a coupling transformer, and is not limited to a planar coil formed by vapor deposition or the like, but can also be a coil of a wire.

[0203] like Figure 18As shown in (a), the first element 50, the primary side 30 of the coupling transformer 20, and the second element 60 of the RFID tag 100 equipped with the coil 30 of the third embodiment are formed by bending a wire, and the coil 30 is wound around it. Figure 18 (b) The outer periphery of the substrate 90.

[0204] like Figure 18 As shown in (b), an RF chip 10 is mounted on the upper part of the patterned coil 40 on the substrate 90. One of the two output terminals of the RF chip 10 is connected to one end of the patterned coil 40, and the other is connected to the other end of the patterned coil 40.

[0205] like Figure 19 As shown, a substrate 90 and a coil 30, which carry an RF chip 10 and a patterned coil 40, are fixed on the housing 75. Furthermore, the substrate 90 and the coil 30 are housed within the housing 75, and are sealed within the housing 75 (not shown) by encapsulation (potting) with resin or the like. From the sealed housing 75, a first element 50 and a second element 60 extend parallel to each other from the coil 30.

[0206] like Figure 20 As shown, a guide portion 77 is formed in the outer casing 75, which serves to maintain the shape of the wire of the coil 30.

[0207] In the RFID tag 100 with coil 30 of the third embodiment, similarly to the RFID tag 100 of the first embodiment, by having coil 30 with fewer coil turns than patterned coil 40, the input of coil 30 connected to the first element 50 and the second element 60 can be set to low impedance, and the output of patterned coil 40 can be converted to high impedance, thereby adapting to the input impedance of RF chip 10.

[0208] Furthermore, in the RFID tag 100 equipped with the coil 30 of the third embodiment, when mounted on a rubber product such as a tire, not only the first element 50 but also the second element 60 is embedded or adhered to the resistive rubber product such as the tire. Through electrical connection, the rubber product such as the tire connected to the second element 60 functions as the ground for the RFID tag 100, thus enabling communication with high sensitivity. Therefore, when mounted on a rubber product such as a tire, it can become an RFID tag 100 with excellent communication characteristics.

[0209] Furthermore, in the RFID tag 100 equipped with the coil 30 of the third embodiment, the coil 30, the first element 50, and the second element 60 are formed by bending a wire, without the need for welding or other connections, thus simplifying the manufacturing process and ensuring high reliability of the electrical connection.

[0210] When the RFID tag 100 with the coil 30 of the third embodiment is installed on a rubber product such as a tire, it can be directly embedded in the rubber product. However, as a resin-sealed RFID tag 155 formed by sealing the outer shell 75 with resin 93, it is preferable to embed the resin-sealed RFID tag 155 in the rubber product to prevent positional displacement of the coil 30 and the substrate 90 during embedding. In addition, since the RF chip 10 can be sealed with resin 93, it can be mounted on the patterned coil 40 in the bare chip state without encapsulation of the RF chip 10.

[0211] As a sealing resin, conventional thermosetting epoxy resins can be used. For example, by incorporating silica (SiO2, silicon dioxide) particles therein, functional properties such as heat dissipation and thermal expansion coefficient are preferably imparted.

[0212] exist Figure 21 A first modified example of an RFID tag 100 equipped with a coil 30 according to the third embodiment is shown. Additionally, in... Figure 22 The image shows a second variation of an RFID tag 100 equipped with a coil 30 according to the third embodiment.

[0213] Figure 21 (a) is a schematic perspective view of an RFID tag 100 having a coil 30 of the first variant. Figure 21 (b) is a schematic top view of an RFID tag 100 having the coil 30 of the first variant. Additionally, Figure 22 (a) is a schematic perspective view of an RFID tag 100 having a coil 30 of the second variation. Figure 22 (b) is a schematic top view of an RFID tag 100 with a coil 30 of the second variant.

[0214] Having Figures 17 to 20 In the RFID tag 100 of the third embodiment shown, the coil 30, wound in a ring shape, is wound around the outer periphery of a square substrate 90. In contrast, in the case of... Figure 21 In the first modified example of the RFID tag 100 with coil 30, the coil 30, wound in a ring shape, is wound around the outer periphery of a cylindrical substrate 90. Additionally, in the case of... Figure 22 In the second variation of the RFID tag 100, the coil 30 is wound in a ring around the substrate 90 in such a way that it abuts against the corner of the square substrate 90.

[0215] In this invention, RF chip 10 is equivalent to "RF chip", coupling transformer 20 is equivalent to "coupling transformer", first element 50 is equivalent to "first element", second element 60 is equivalent to "second element", substrate 90 is equivalent to "substrate", coil 30 / primary side 30 is equivalent to "coil", patterned coil 40 / secondary side 40 is equivalent to "patterned coil", housing 75 is equivalent to "housing", storage part 76 is equivalent to "storage part", slot 65 and guide part 77 are equivalent to "guide part", RFID tag 100 and resin sealed RFID tag 155 are equivalent to "RFID tag".

[0216] The preferred embodiments of the present invention have been described above, but the present invention is not limited thereto. It should be understood that various embodiments without departing from the spirit and scope of the present invention are included. Furthermore, although the effects and benefits of the structure of the present invention have been described in this embodiment, these effects and benefits are merely examples and are not intended to limit the present invention.

[0217] Explanation of reference numerals in the attached figures

[0218] 10RF chip

[0219] 20 coupling transformer

[0220] 30 coils

[0221] 40 patterned coil

[0222] 50 First Component

[0223] 60 Second Component

[0224] 75 casing

[0225] 76 Storage Department

[0226] 77 Guiding Department

[0227] 90 substrate

[0228] 100 RFID tags

[0229] 160 tires

[0230] 500 RFID tags built into tires

Claims

1. A coil for an RFID tag, used in an RFID tag having an RF chip and a substrate with a patterned coil connected to the RF chip, and embedded in the rubber of a tire, wherein, The coil is held in an annular groove within a housing that contains the substrate, and surrounds the substrate. The first end of the coil protrudes from the housing to form the first element of the antenna. The second end of the coil protrudes from the housing to form the second element of the antenna. The first element is arranged parallel to the second element, and the first element has a longer extension length compared to the second element. The coil and the patterned coil form a coupling transformer, and the number of turns of the coil is smaller than the number of turns of the patterned coil.

2. The coil for an RFID tag as described in claim 1, wherein, The coil and the first and second elements at the ends of the coil are formed by bending a wire.

3. The coil for an RFID tag as described in claim 1, wherein, The outer casing has a guide portion that maintains the shape of the coil and a receiving portion that houses the substrate. The axis of the patterned coil is the same as the axis of the coil.

4. The coil for an RFID tag as described in claim 3, wherein, When the wavelength of the radio wave in the communication frequency of the RFID tag is set to λ, the electrical length of the first element is λ / 4, λ / 2, 3λ / 4 or 5λ / 8.

5. The coil for an RFID tag as described in claim 4, wherein, The coil and the substrate are encapsulated in the housing by resin.

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