JP2005309811A - Rfid tag and rfid system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an RFID tag and an RFID system which can be set on a metal and operated in a high frequency band such as UHF band or SHF band. <P>SOLUTION: This RFID tag comprises a soft magnetic material 9, or soft magnetic material 9 and a spacer 11, or a spacer 11, the soft magnetic material 9 and a spacer 11 provided on an attachment face of an antenna 3 such as a dipole antenna operated in UHF band or SHF band. The soft magnetic material 9 (preferably, a soft magnetic mateiral composed of a composite mateiral of a soft magnetic powder or soft magnetic flake with plastics or rubber) is interposed, whereby the influence of the metal can be suppressed. Further, the spacer 11 (preferably, a spacer with low dielectric constant such as porous plastics or a frame mamber) is arranged between the antenna 3 and the soft magnetic material 9, or between the soft magnetic mateiral 9 and a metallic article 10, or instead of the soft magnetic mateiral 9, whereby the influcence of both the metal and the soft magnetic material can be suppressed, and the tag 2 can be operated even on the metallic article 10. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an RFID tag and an RFID system, and more particularly to an RFID tag and an RFID system used in a high frequency band such as a UHF band and an SHF band.

  In recent years, RFID systems that perform data communication between a tag including an IC chip and a reader, writer, or reader / writer (hereinafter collectively referred to as a reader / writer) have become widespread. Since this RFID system communicates data using the antennas provided to each of the tag and the reader / writer, it can communicate even when the tag is separated from the reader / writer, and it is resistant to dirt, etc. It has come to be used for various purposes such as factory production management, logistics management, and entrance / exit management.

  In the RFID system, the communicable distance differs depending on the frequency band to be used. For example, in the short wave band of about 13.56 MHz, the communication distance is several centimeters to several tens of centimeters. When this system is used for entrance / exit management or the like, the tag is used close to the reader / writer. However, a longer communication distance is more advantageous for applications such as logistics management. Therefore, in such an application, a higher frequency band such as a UHF band or an SHF band is used.

  As a tag antenna, a loop antenna is usually used in a short wave band, but in a high frequency band such as a UHF band or an SHF band, a dipole antenna (for example, JP-A-2003-249820) or one surface of a substrate is used. A microstrip line type antenna or the like in which a microstrip conductor is formed on the surface and a back surface grounding conductor is formed on the surface on the article side is used.

JP 2003-249820 A (page 4-8, FIG. 1)

  A tag that operates in the UHF band or SHF band provided with the above-mentioned dipole antenna does not operate when placed close to a metal, such as placed directly on a metal article. Therefore, when the tag is attached to a metal, as shown in FIG. 8, a spacer 12 made of plastic, rubber, or the like is disposed between the tag 2 and the metal article 10 to place the tag between the metal article 10 and the antenna 3. A method is used in which a certain distance is provided to suppress the influence of metal.

  However, if the spacer 12 is made thinner and the distance between the metal article 10 and the antenna 3 is made smaller, the operation becomes impossible or the working distance becomes smaller, while the spacer 12 is made thicker and the distance between the metal article 10 and the antenna 3 is made smaller. However, the working distance increases, but the tag 2 protrudes from the article, and there is a problem that there is an increased risk of contact with the surrounding article and damage during handling.

  The present invention has been made in view of the above problems, and a main object thereof is to provide an RFID tag and an RFID system that can be installed on a metal and operate in a high frequency band such as a UHF band and a UHF band. It is in.

  In order to achieve the above object, an RFID tag of the present invention is an RFID tag including a dipole antenna, and includes a soft magnetic material on a surface of the dipole antenna attached to a metal-containing article, or a metal-containing content of the dipole antenna. A soft magnetic material and a spacer are provided on the attachment surface to the article from the metal-containing article side, or a spacer and a soft magnetic material are provided on the attachment surface to the metal-containing article of the dipole antenna from the metal-containing article side. And a spacer.

  The RFID tag of the present invention is an RFID tag including a dipole antenna, and is composed of a porous plastic or porous rubber on a surface where the dipole antenna is attached to a metal-containing article, or a frame member including a hollow region inside. A spacer is provided.

  Further, the RFID system of the present invention is an RFID system including an RFID tag having a dipole antenna and a reader or a reader / writer, wherein a soft magnetic material is disposed on a surface of the RFID tag attached to a metal-containing article, Alternatively, a soft magnetic material and a spacer are disposed on the surface of the RFID tag attached to the metal-containing article from the metal-containing article side, or the metal surface of the RFID tag is attached to the metal-containing article. From the contained article side, a spacer, a soft magnetic material, and a spacer are arranged.

  The RFID system of the present invention is an RFID system including an RFID tag having a dipole antenna and a reader or a reader / writer, and a porous plastic or porous rubber is attached to a surface of the RFID tag attached to a metal-containing article. Or the spacer which consists of a frame member containing a hollow area | region inside is arrange | positioned.

  In this invention, the said spacer can be set as the structure which consists of a frame member containing a hollow area | region inside porous plastic or porous rubber, or inside.

  In the present invention, the soft magnetic material may be composed of a composite material of soft magnetic particles or soft magnetic flakes and plastic or rubber.

  In the present invention, the RFID tag preferably operates in the UHF band, the SHF band, or the like.

  Thus, in the present invention, a soft magnetic material (preferably a soft magnetic powder or soft magnetic flake and a composite material of plastic or rubber is provided between a high-frequency antenna such as a dipole antenna and a member containing metal. Since the magnetic material is interposed, the influence of the metal can be suppressed by the soft magnetic material to increase the working distance, and the RFID tag can be attached to the metal-containing article for use. Also, a spacer (preferably porous plastic such as urethane foam or porous rubber, between the dipole antenna and the soft magnetic material, between the soft magnetic material and the metal-containing article, or in place of the soft magnetic material, By disposing a spacer having a low dielectric constant, such as a frame member including a hollow region, the influence of both the metal and the soft magnetic material can be suppressed, so that the working distance can be further increased.

  As described above, according to the RFID tag and the RFID system of the present invention, the RFID tag used in a high frequency band such as the UHF band and the UHF band can be used by being attached to a metal article. .

  The reason is that the antenna (dipole antenna) constituting the tag is not directly installed on the metal article (the article made of metal or the article including the metal), but the soft magnetic material is interposed between the metal article and the dipole antenna. This is because the soft magnetic material (preferably a soft magnetic material made of a composite material of soft magnetic powder or soft magnetic flakes and plastic or rubber) is disposed, and the influence of the metal article can be suppressed by this soft magnetic material.

  Also, between the dipole antenna and the soft magnetic material, between the soft magnetic material and the metal article, or instead of the soft magnetic material, a spacer (preferably a porous plastic such as urethane foam or porous rubber, This is because the influence of both the metal and the soft magnetic material can be suppressed by arranging a spacer having a low dielectric constant such as a frame member including a hollow region.

  As shown in the prior art, when a tag antenna used in a high-frequency band such as the UHF band or the SHF band is installed on a metal article, it does not operate due to an eddy current flowing in the metal, or the working distance becomes small. There was a problem. Therefore, conventionally, a method of inserting a spacer such as plastic or rubber between the antenna and the metal article to move the antenna away from the metal article has been used. However, if the spacer is thin, the working distance becomes small and the spacer becomes thick. If so, the antenna may protrude from the surface of the metal article and be damaged.

  On the other hand, the inventor of the present application, in JP-A-2002-215321, consists of a composite of soft magnetic alloy powder or flakes and plastic between the antenna and the metal article in order to suppress the influence of the metal article. A technique for disposing a soft magnetic material is disclosed. By using the method described in the publication, an RFID tag that operates even on a metal article or an antenna for an RFID reader / writer can be formed.

  However, the technique described in the above publication relates to an antenna used in a frequency band of HF band or VHF band (for example, 13.56 MHz), and uses an antenna that operates in a high frequency band such as a UHF band or an SHF band. There is no idea in the field to place soft magnetic materials in the first place. Even if a soft magnetic material is disposed, loss increases in a high frequency band such as the UHF band and the SHF band, and the soft magnetic powder is made finer in order to be usable in the high frequency band. Although it is necessary, in the production of the soft magnetic material, the flakes are recombined even if pulverized for a long time with an attritor.

  Therefore, in the present invention, the influence of metal or soft magnetic material is suppressed by arranging a soft magnetic material for the antenna operated in a high frequency band such as UHF band or SHF band, or by giving a characteristic to the structure of the spacer. doing. As the soft magnetic material, a soft magnetic material having an arbitrary structure (for example, the structure described in the above publication) can be used. In order to reduce loss in a high frequency band such as the UHF band and the SHF band, Using extremely fine soft magnetic metal powder, this soft magnetic metal powder is compounded with plastic or rubber, and the material is unidirectionally extruded, rolled, rolled after extrusion, drawn after extrusion, or rolled after injection. It can be manufactured by applying a direct current magnetic field after applying to a film an ink in which a soft magnetic metal powder is suspended in a solvent in which a plastic is dissolved, and then applying a direct current magnetic field. In addition, a spacer having an arbitrary structure can be used as the spacer, but in order to suppress loss due to the spacer itself, a porous plastic or porous rubber having bubbles formed therein, and a frame member including a hollow region inside Can be used. Hereinafter, the specific structure will be described with reference to the drawings.

  First, an RFID tag and an RFID system according to a first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a diagram schematically illustrating a general configuration of an RFID system. FIG. 2 is a diagram schematically showing the configuration of the tag of this embodiment, where (a) is a top view, (b) is a side view seen from the A direction, and (c) is a side view seen from the B direction. FIG. Moreover, FIG. 3 is a figure which shows typically the manufacturing method and sectional structure of a soft-magnetic material utilized for the tag of a present Example. In the following description, the structure of the present invention is applied to a tag. However, the present invention is not limited to the following embodiments, and the structure of the present invention is applied to an antenna for a reader or a reader / writer. You can also.

  As shown in FIG. 1, the RFID system 1 according to the present embodiment includes a tag 2 and a reader / writer (or reader) 6 that perform data communication using a high frequency band such as a UHF band or an SHF band. Includes an antenna 3 that constitutes a resonance circuit and an IC chip 5 that stores information. A reader / writer (or reader) 6 transmits a transmission / reception signal to / from a reader / writer antenna 7 that communicates with the antenna 3 of the tag 2. And a control unit 8 such as an arithmetic processing circuit 8b for decoding a transmission / reception signal. The tag 2 is driven using a built-in power source or a power source supplied from a reader / writer 6. . Data communication is performed by matching the resonance frequency of the tag 2 and the reader / writer antenna 7 with the carrier frequency.

  Further, as shown in FIG. 2, the tag 2 has an antenna 3 (preferably a dipole antenna) operating in the UHF band or SHF band and an IC chip 5 disposed on one surface of a soft magnetic material 9. The tag 2 is configured and placed on the surface of an article or a casing, particularly on an article or casing containing a metal material (hereinafter referred to as a metal article 10). In this specification, the antenna 2, the IC chip 5, and the soft magnetic material 9 are referred to as a tag 2, but the one excluding the soft magnetic material 9 is referred to as a tag, and the tag and the metal article 10. It is good also as a form which arrange | positions the soft-magnetic body 9 formed as a separate body between.

  Further, the structure of FIG. 2 is an example, and as long as the soft magnetic material 9 is disposed between the antenna 3 and the metal article 10, the shape of the antenna 3, the shape of the soft magnetic material, the thickness, etc. are particularly limited. Not. For example, FIG. 2 shows a dipole antenna in which two antenna elements are arranged in a straight line as the antenna 3, but any antenna that can operate in a frequency band such as the UHF band or the SHF band may be used. Of the two antenna elements of the dipole antenna, the monopole antenna and the two dipole antennas that are mirror images by dropping the GND side on the casing are arranged in a cross shape with a 90 degree phase shift and circular polarization It is good also as a turn style antenna etc. which radiate. The antenna 3 and the IC chip 5 may be directly disposed on the soft magnetic material 9, or a film or a substrate (for example, the existing tag 2) including the antenna 3 formed by etching a conductive thin film is softened. It is good also as a structure affixed on the magnetic material 9, and can also be set as the structure by which the soft-magnetic material 9, the antenna 3 on it, and the IC chip 5 whole are protected by the film etc.

  The soft magnetic material 9 may be a general soft magnetic material or a soft magnetic material manufactured using the method described in the prior application of the present inventor (Japanese Patent Laid-Open No. 2002-215321). However, in order to reduce the loss, it is also possible to use an extremely fine soft magnetic metal powder combined with plastic or rubber.

  This extremely fine soft magnetic powder is linked in a chain form due to spontaneous magnetization. When this soft magnetic powder is combined with plastic or rubber and stretched in one direction as shown in FIG. 3A, or a direct current magnetic field is applied to a film coated with ink in which soft magnetic metal powder is suspended, FIG. As shown in (b), aggregates of chain-connected powders are aligned in the extended direction. When a magnetic field is applied in the direction in which the material is extended, the magnetic flux in the extended direction can be increased by passing the aggregate of the chain-like powder. On the other hand, in the direction orthogonal to the extended direction, the powder is not connected, so the magnetic permeability is low, and since the powder is fine, there is no influence of the eddy current flowing inside the powder. Accordingly, if the powder content is adjusted so that the powder is not connected to each other in the direction orthogonal to the magnetization direction, it can be used even at a high frequency exceeding 40 MHz. The following powders are suitable as such powders.

1. Powder obtained by reducing metal oxides, for example, nickel powder obtained by thermally reducing organic oxides such as nickel, cobalt or iron, such as oxalic acid, at low temperature with hydrogen, Examples include cobalt powder or iron powder, and fine iron powder obtained by neutralizing and oxidizing a ferrous sulfate solution.

2. Powder obtained by vapor phase method There are nickel powder, cobalt powder or iron powder obtained by evaporating and evaporating metal such as nickel, cobalt or iron under reduced pressure and solidifying in a vapor phase.

3. Powder reduced in solution There are nickel powder, cobalt powder, and the like obtained by hydrogen reduction of a solution containing ammonia complex ions of nickel or cobalt at high temperature and high pressure.

4). Examples thereof include carbonyl nickel powder, carbonyl iron powder, nickel carbonyl (Ni (CO) ₄ ), carbonyl nickel powder obtained by pyrolyzing iron carbonyl (Fe (CO) ₅ ), and carbonyl iron powder.

  Since these powders are extremely fine, a protective layer such as an oxide layer or an organic compound is provided on the surface to prevent ignition in the atmosphere. However, these protective layers cannot prevent powders from contacting each other and eddy currents flowing between the powders. Therefore, in order to prevent the powders from coming into direct contact with each other, the content of the powder is desirably 40% (hereinafter referred to as 40 v%) or less by volume ratio. In addition, since the specific resistance of these materials is small, but the particle size of the powder is also small, eddy current does not flow if there is no contact between the powders. In addition, the lower the powder content, the easier it is to process such as rolling, and the resulting composite material is also flexible, so it is necessary to bend the antenna in order to mount it on a curved surface, roll the antenna, etc. If there is, the content may be reduced as appropriate. On the other hand, when the powder content decreases, the magnetic permeability decreases, so that a powder content of 10 v% or less is not appropriate.

  Further, the powder having the protective layer does not ignite even when handled in the atmosphere, but cannot prevent long-term oxidation. However, when the powder is made of a composite material with plastic, the plastic stops the contact between the powder and the atmosphere, so that the composite material of the present invention also has an effect of preventing deterioration due to oxidation.

  Then, the powder having the above content is heat-kneaded with polyethylene, polypropylene, nylon, vinyl chloride, fluorine resin, etc., and then subjected to a process of extending in one direction such as extrusion, rolling, and rolling the extruded material. In addition, after applying the ink in which the powder is suspended in the solvent in which the plastic is dissolved to the film, and before drying, a direct current magnetic field is applied to manufacture the ink. Although the fine powder is spherical, it is attracted to each other by the spontaneous magnetization of the powder and connected in a chain form, but the plastic containing it is stretched in one direction, or the aggregate of powder is stretched by applying a DC magnetic field. Can be aligned in different directions.

  The soft magnetic material thus manufactured has a high permeability in the extended direction and a low permeability in the direction perpendicular thereto. For this reason, if the antenna is installed so that the method with high magnetic permeability is in the direction of the magnetic component, the magnetic flux does not leak from the upper and lower surfaces and side surfaces, but all comes out from the end surface. A thin RFID tag or an antenna for a reader / writer that operates in the SHF band and can be used in close contact with a metal article can be manufactured. The materials and manufacturing methods described above are only examples, and other materials and manufacturing methods can be used as long as a magnetic core material having high magnetic permeability, good dimensional accuracy, and being hard to break can be manufactured.

  Thus, between the UHF band or SHF band antenna 3 (dipole antenna) and the metal article 10, the soft magnetic material 9 (preferably, a composite material of soft magnetic powder or soft magnetic flakes and plastic or rubber is used. By placing a soft magnetic material 9, more preferably, a soft magnetic material 9 made of a composite material of soft magnetic powder or soft magnetic flakes having a predetermined particle size (approximately 1 μm) or less and plastic or rubber, a metal article is provided. An antenna for the UHF band or the SHF band that operates even on 10 can be formed. Also, the soft magnetic metal powder and plastic or rubber are kneaded and subjected to a process of extending the composite material in one direction such as extrusion, rolling, post-extrusion rolling, post-extrusion drawing, or post-injection rolling, or plastic. By applying a DC magnetic field after applying the ink in which the above powder is suspended in a dissolved solvent to a film and before drying, the magnetic permeability can be increased and the direction can be made dependent.

  Next, an RFID tag and an RFID system according to a second embodiment of the present invention will be described with reference to FIGS. 4A and 4B are diagrams schematically showing the configuration of the tag of this embodiment, where FIG. 4A is a top view, FIG. 4B is a side view seen from the A direction, and FIG. 4C is a side view seen from the B direction. It is. FIG. 5 is a diagram schematically showing the structure of the spacer, and FIGS. 6 and 7 are diagrams showing variations in the configuration of the tag of this embodiment.

  In the first embodiment described above, only the soft magnetic material 9 is disposed between the antenna 3 and the metal article 10. However, when the soft magnetic material 9 is close to the antenna 3, the soft magnetic material 9 itself causes a loss. This increases the problem that the Q value decreases. Therefore, in this embodiment, a structure that suppresses the influence of both the metal article 10 and the soft magnetic material 9 will be described.

  As shown in FIG. 4, the tag 2 of the present embodiment has a soft magnetic material 9 (preferably a soft magnetic material 9 manufactured by the method shown in the first embodiment) on one surface of a normal plastic or A spacer 11 having a dielectric constant smaller than that of rubber or the like is disposed, and an antenna 3 (preferably a dipole antenna) operating in the UHF band or SHF band and an IC chip 5 are disposed on the spacer 11. Is placed on the metal article 10. Also in this embodiment, as long as the soft magnetic material 9 and the spacer 11 are arranged in this order between the antenna 3 and the metal article 10 from the metal article 10 side, the shape of the antenna 3 and the soft magnetic material 9 The shape, thickness, etc. of the spacer 11 are not particularly limited. The antenna 3 may be any antenna that can operate in a frequency band such as the UHF band or the SHF band, and may be a dipole antenna, a monopole antenna, a turn style antenna, or the like.

  Here, plastics (dielectric constant 2 to 3), rubber or the like has been conventionally used as the spacer 11 as shown in FIG. 8, but when the dielectric constant of the spacer 11 increases, the loss due to the spacer 11 itself increases. Therefore, in this embodiment, as shown in FIG. 5A, the spacer 11 is made of a porous plastic such as foamed urethane (dielectric constant 1.1 to 1.2) or porous rubber in which bubbles are mixed. The frame member 11b is formed using plastic or the like, and the dielectric constant is reduced by the air layer in the frame.

  The structure shown in FIG. 5 is merely an example, and any structure that can make the dielectric constant smaller than that of ordinary plastic or rubber may be used. If the foamed urethane 11a has insufficient strength, the foamed urethane 11a is made of plastic. It may be inserted, or an air layer may be formed in the spacer 11 by processing the plastic into a corrugated shape as shown in FIG. In FIG. 5B, the frame member 11b has a rectangular tube shape, but the shape of the frame is also arbitrary, and it has a box-type structure in which the inside is sealed, or a gas with a low dielectric constant (for example, Helium gas or the like) may be sealed, or a structure in which the antenna 3 is supported by a support may be employed.

  In FIG. 4, the soft magnetic material 9 and the spacer 11 have the same size, but the spacer 11 only needs to have a structure that can increase the distance between the soft magnetic material 9 and the antenna 3. Is not particularly limited. Further, the soft magnetic material 9 and the spacer 11 do not need to be laminated. For example, as shown in FIG. 7A, a U-shaped frame member 11b whose end is in contact with the metal article 10 is used. A structure that covers the soft magnetic material 9 may also be adopted.

  Thus, between the antenna 3 and the metal article 10, from the metal article 10 side, the soft magnetic material 9 (preferably soft magnetic powder or soft magnetic flakes having a predetermined particle size (approximately 1 μm) or less, and plastic or rubber The soft magnetic material 9) made of the composite material and the spacer 11 made of the foamed urethane 11a and the frame member 11b having a small dielectric constant are arranged to suppress the influence of both the metal article 10 and the soft magnetic material 9 to operate. A tag 2 for UHF band or SHF band having a large distance can be formed.

  In FIG. 4, the spacer 11 is provided between the soft magnetic material 9 and the antenna 3. However, as a variation of the structure using the soft magnetic material 9 and the spacer 11, as shown in FIG. A spacer 11 having a small dielectric constant can also be disposed between the soft magnetic material 9.

  Also in this structure, the type and shape of the antenna 3 and the shapes and thicknesses of the soft magnetic material 9 and the spacer 11 are not particularly limited. Further, the structure of the spacer 11 includes a plurality of materials including a porous plastic or a porous rubber such as urethane foam as shown in FIG. 5A, a frame member 11b as shown in FIG. 5B, and a material having a low dielectric constant. A multilayer structure of seed materials, a structure including an air layer such as a corrugation, a structure in which a gas having a low dielectric constant is sealed inside the box, and a structure in which the antenna 3 is supported by a column are also possible. Further, the soft magnetic material 9 and the spacer 11 do not need to be laminated. For example, as shown in FIG. 7B, the soft magnetic material 9 is arranged inside a box-shaped frame member 11b. You can also.

  4, 6, and 7, the soft magnetic material 9 is interposed between the antenna 3 and the metal article 10, but the spacer 11 has a structure that can reduce the dielectric constant as shown in FIG. 5. When used, the working distance can be increased because the loss of the spacer 11 itself can be suppressed as compared with the conventional structure using a plastic or rubber having a high dielectric constant. Therefore, a structure in which only the spacer 11 having a low dielectric constant is disposed on the metal article 10 and the antenna 3 is directly formed thereon can be employed.

  Next, in order to confirm the effect of the present invention, the tag 2 having the structure shown in FIGS. 2, 4, and 6, the tag 2 having only the antenna 3 that does not use the spacer 11 and the soft magnetic material 9, and a low dielectric constant. The tag 2 on which only the spacer 11 (foamed urethane 11a) was placed was placed on an aluminum plate, and the thickness of the entire tag 2 and the working distance (the limit distance mm for working on the aluminum plate) were measured. The results are shown in Table 1.

  According to Table 1, the sample (sample 1) in which the antenna 3 was directly arranged on the aluminum plate did not work, but a urethane foam 11a (density 200 g / l) having a thickness of 1 mm was arranged between the tag 2 and the aluminum plate. In the sample (sample 2), the working distance is 9 mm, and in the sample (sample 3) in which the soft magnetic material 9 (composite material of granular iron and epoxy resin) having the same thickness is disposed instead of the urethane foam 11a. The working distance is increased to 15 mm, and the soft magnetic material 9 (iron-based material) is placed between the foamed urethane 11 a having a thickness of 2 mm and 0.5 mm than the sample (sample 5) having the foamed urethane 11 a having a thickness of 1 mm. The sample (sample 6) in which the composite material of alloy, flakes and polyethylene (thickness 0.5 mm) is disposed has a larger working distance despite the fact that the overall thickness is reduced. Intervening That more working distance increases could be confirmed.

  Compared with the sample (sample 3) in which the antenna 3 is directly disposed on the soft magnetic material 9, the antenna 3 and the soft magnetic material 9 (composite material of iron-based alloy, flakes and polyethylene, thickness 0.45 mm) are used. In the sample (sample 4) in which the foamed urethane 11a (thickness 0.5 mm) is disposed between the working distances up to 21 mm, the antenna 3 is further away from the soft magnetic material 9 and the working distance is longer. It was confirmed that it became larger.

  Further, since the working distance is significantly improved in the sample (sample 5) in which the thickness of the urethane foam 11a is 4 mm as compared with the sample (sample 2) in which the thickness of the urethane foam 11a is 1 mm, only the spacer 11 is used. Even with the structure, it was confirmed that the working distance could be sufficiently improved by using a material having a low dielectric constant.

  The present invention can be applied not only to antenna applications of RFID systems, but also to any high-frequency antenna used on metal-containing articles.

1 is a diagram schematically illustrating a general configuration of an RFID system. It is the top view and side view which show typically the structure of the tag which concerns on 1st Example of this invention. It is a perspective view which shows typically the manufacturing method and sectional structure of the soft-magnetic material which concern on this invention. It is the top view and side view which show typically the structure of the tag which concerns on 2nd Example of this invention. It is a figure which shows the structure of the spacer used for the tag which concerns on the 2nd Example of this invention. It is the top view and side view which show typically the other structure of the tag which concerns on the 2nd Example of this invention. It is a side view which shows typically the other structure of the tag which concerns on the 2nd Example of this invention. It is the top view and side view which show the structure of the conventional tag typically.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 RFID system 2 Tag 3 Antenna 5 IC chip 6 Reader / writer 7 Reader / writer antenna 8 Control part 8a Communication circuit 8b Arithmetic processing circuit 9 Soft magnetic material 10 Metal article 11 Spacer 11a Urethane foam 11b Frame member 12 Spacer

Claims (14)

An RFID tag having a dipole antenna,
An RFID tag comprising a soft magnetic material on an attachment surface of the dipole antenna to a metal-containing article. An RFID tag having a dipole antenna,
An RFID tag comprising a surface of the dipole antenna attached to a metal-containing article and a soft magnetic material and a spacer from the metal-containing article side. An RFID tag having a dipole antenna,
An RFID tag comprising a spacer, a soft magnetic material, and a spacer on a surface of the dipole antenna attached to a metal-containing article from the metal-containing article side.   4. The RFID tag according to claim 2, wherein the spacer is made of porous plastic or porous rubber, or a frame member including a hollow region inside.   The RFID tag according to any one of claims 1 to 4, wherein the soft magnetic material is made of a composite material of soft magnetic particles or soft magnetic flakes and plastic or rubber. An RFID tag having a dipole antenna,
An RFID tag comprising a spacer made of porous plastic or porous rubber or a frame member including a hollow region inside on a surface of the dipole antenna attached to a metal-containing article.   The RFID tag according to any one of claims 1 to 6, wherein the RFID tag operates in a UHF band or an SHF band. An RFID system comprising an RFID tag comprising a dipole antenna and a reader or reader / writer,
An RFID system, wherein a soft magnetic material is disposed on a surface of the RFID tag attached to a metal-containing article. An RFID system comprising an RFID tag comprising a dipole antenna and a reader or reader / writer,
An RFID system, wherein a soft magnetic material and a spacer are disposed on a surface of the RFID tag attached to a metal-containing article from the metal-containing article side. An RFID system comprising an RFID tag comprising a dipole antenna and a reader or reader / writer,
An RFID system, wherein a spacer, a soft magnetic material, and a spacer are disposed on a surface of the RFID tag attached to a metal-containing article from the metal-containing article side.   11. The RFID system according to claim 9, wherein the spacer is made of porous plastic or porous rubber, or a frame member including a hollow region inside. 11.   The RFID system according to any one of claims 8 to 11, wherein the soft magnetic material is made of a composite material of soft magnetic particles or soft magnetic flakes and plastic or rubber. An RFID system comprising an RFID tag comprising a dipole antenna and a reader or reader / writer,
An RFID system, wherein a spacer made of porous plastic or porous rubber or a frame member including a hollow region is disposed on a surface of the RFID tag attached to a metal-containing article.   The RFID system according to any one of claims 8 to 13, wherein the RFID tag operates in a UHF band or an SHF band.

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