JP4796180B2 - RFID tag - Google Patents

Description

  The present invention relates to an RFID tag, its communication method, and an RFID tag detection instrument. In particular, it is compatible with a metal that requires a reduction in size that cannot be handled by an RFID tag using a half-wave antenna at a communication frequency in a micro band or UHF band. The present invention relates to an RFID tag suitable for use in an RFID tag application field, its communication method, and an RFID tag detection device.

  In general, an RFID tag integrally mounts an IC chip in which identification information such as an ID number is incorporated in an integrated circuit, an impedance matching circuit connected to the IC chip, an antenna to which the matching circuit is connected, and the antenna. A utility such as a protective film or an adhesive for attachment is added to the inlet made of a base material. Through the IC chip, the matching circuit, and the antenna, identification information such as an ID number is communicated with the wireless communication means from the outside by a reader / writer in the IC chip.

  When this general RFID tag is attached to the surface of a metal object and operated, reflection or absorption occurs on the metal surface attached to electromagnetic waves for communication. Therefore, there is a disadvantage that communication becomes difficult. In the prior art, as countermeasures against this, a dielectric resin or magnetic material that prevents the signal from being consumed as eddy current or induced current on the metal surface or the surface of the RFID tag's own clasp and reduces the influence. An RFID tag for a metal surface, in which the inlet is incorporated in a body ferrite, has been put into practical use. Further, in fields requiring mechanical strength, proposals have been made to protect the entire metal-compatible RFID tag with a large metal fitting. However, these methods have a disadvantage that the RFID tag becomes large.

  If it is a very small tag, the installation location can be small. For example, Non-Patent Document 1 discloses an RFID tag in which a logic circuit and an antenna are built on the same semiconductor substrate.

As another method, as disclosed in Patent Document 1, there is also a method in which a mounting metal surface is directly processed and incorporated.
In Patent Document 1, as a method of communicating with an RFID tag installed in a deep space such as a gap or inside of a metal surface, the inside of a medium, the inside of a waveguide, or the inside of a coaxial cable or a coaxial tube, etc. A technique has also been proposed in which an RFID tag is installed in an opening at one end of a transmission line and the reader / writer communicates from the other opening using the characteristic that electromagnetic waves propagate through the other transmission line.
Further, in Patent Document 1, as a small metal-compatible tag using a micro loop antenna, not only the support metal plate on a metal plate is also used as a one-turn micro loop antenna, but also an IC chip or a matching circuit. An example is also disclosed in which the metal plate is supported so as to be isolated by a support metal fitting so as not to be short-circuited by a metal surface or the like to be attached.
Patent Document 1 also proposes an example in which a dielectric spacer is disposed on a small metal RFID tag attached to a metal surface, and a protective cover and ground type resonance device is covered thereon.

Patent Document 2 has a structure in which two circular metal plates having a diameter of about 1/10 of the wavelength of a communication electromagnetic wave, for example, are connected on the front and back at a part of the peripheral portion with a dielectric sandwiched between them. A small metal-compatible tag has been proposed in which an IC chip is electrically connected in the vicinity of the radiation electrode of the connecting portion, with the ground electrode as the ground electrode and the upper surface as the radiation electrode.
Further, Patent Document 2 discloses that in order to improve the sensitivity of the RFID tag attached to the metal surface, an auxiliary antenna such as a dipole antenna is disposed on the radiation electrode side via a dielectric sheet to increase the communication distance. ing.
In Patent Document 3, a micro loop antenna having a length of about 1/10 of the wavelength of a communication electromagnetic wave is formed of a metal plate or a support, and the IC chip or the matching is formed at a predetermined height from the metal surface with this support. An example of isolating so as not to short circuit is disclosed.
Further, in Patent Document 4, an IC chip is mounted on the front side of the folded metal plate or the side of the connecting portion with the back side metal plate, and the length in the longitudinal direction of the front and back metal plates is about ¼ of the wavelength of the communication electromagnetic wave. An example of a tag functioning as an antenna that can realize a long communication distance at a length of is disclosed.
Further, in Patent Document 5, an IC chip is electrically connected to and mounted on a band-shaped minute loop antenna made of a metal plate, and a high-frequency current is passed through the attached conductor surface side to emit electromagnetic waves from the side on which the IC chip is mounted. Examples of tags are disclosed.

JP 2008-90813 A JP 2006-333403 A JP 2008-123222 A JP 2005-191705 A JP 2006-53833 A

http://www.hitachi.co.jp/New/cnews/030902a.html: Built-in antenna type “Muchip (registered trademark)”, September 2, 2003

  The conventional RFID tag has the above-described disadvantages when attached to a metal surface, that is, it is difficult to communicate because reflection or absorption occurs on the metal surface attached to electromagnetic waves for communication. Therefore, the metal RFID tag devised to solve the problem that RFID communication is impossible is approximately half a wavelength, and when the communication frequency to be used is 2.45 GHz, the approximate dimension is from 50 mm. It is 60mm, and it is difficult to attach to a metal surface smaller than this dimension.

  Since the RFID tag with a built-in antenna disclosed in Non-Patent Document 1 is arranged parallel to the mounting surface, if this is installed on a metal surface, will it contact the metal surface on which the antenna of the tag is installed and short-circuit? The built-in antenna is capacitively coupled to the metal surface, and high-frequency currents flow in opposite directions to the image antenna projected in parallel inside the metal surface. The self-antenna and the electromagnetic induction cancel each other, making it difficult to emit electromagnetic waves to the outside. Resulting in. Therefore, it cannot be installed on the metal surface.

The tag structure disclosed in Patent Document 1 is a minute loop antenna-sized metal fitting that has a winding start point and an end point and is not closed. A minute inlet is built in, and the minute structure is located near each start point and end point. It arrange | positions so that the antenna part of an inlet may electromagnetically couple. The IC chip of the RFID tag is disposed so as to be exposed in the electromagnetic wave radiation direction immediately below the discontinuous portion of the minute loop antenna fitting that is not closed, that is, the opening portion. Since the opening portion of the minute loop antenna bracket and the surrounding slot portion are not protected by metal, the IC chip is easily peeled off due to inferior mechanical strength against rust removal by washing with high pressure jet water or sandblasting. There are issues such as.
Furthermore, the method of directly processing and incorporating the attachment metal surface has a problem of increasing the processing load. For this reason, there is an increasing demand for downsizing of RFID tags.
In addition, the technique of Patent Document 1 in which an RFID tag is installed in one opening of a transmission line and communication is performed by a reader / writer from the other opening is a permanent installation of the transmission line or various transmission lines. There is a problem that it is difficult to temporarily attach externally to various types of readers / writers and to integrate them only when necessary, or to easily remove them when unnecessary.
Furthermore, the method of isolating with the support metal fitting of patent document 1 is difficult to implement | achieve the metal corresponding | compatible tag made smaller than the support metal fitting dimension. On the other hand, a device that integrates a loop-shaped probe, coaxial cable, and dipole antenna elements to identify small tags increases the overall size of the device and increases the loss between the elements of the device, reducing sensitivity. There is a problem that it ends up.

The metal-compatible tag disclosed in Patent Document 2 having a ground electrode on the lower surface and a radiation electrode on the upper surface is difficult to make a tag smaller than the size of the radiation electrode. In addition, the IC chip may be destroyed by an external electric shock such as static electricity or surge current on the radiation electrode. Furthermore, the method of disposing an auxiliary antenna on the radiation electrode side through a dielectric sheet and lengthening the communication distance in Patent Document 2 is difficult to apply when the installation location of the mounting metal surface is equal to or smaller than the size of the auxiliary antenna. There are challenges.
In addition, in the RFID tag disclosed in Patent Document 2, there is an example in which the IC chip portion installed in the direction of electromagnetic wave radiation is covered with a protective layer such as a resin. Since it is exposed, there are problems in electrical and mechanical strength.
Furthermore, it is difficult for the method disclosed in Patent Document 3 to realize a small metal-compatible tag having a size equal to or smaller than the size of a support metal fitting that forms a minute loop antenna. Furthermore, since the IC chip and the impedance matching circuit are electrically connected to the minute loop antenna, there is a possibility that the IC chip is destroyed by an external electric shock such as static electricity or surge current. In addition, there are cases where the IC chip part installed in the direction of electromagnetic wave radiation is covered with resin, etc., but it is easily exposed to the outside by cleaning work with high-pressure jet water etc., so there is a problem in electrical and mechanical strength. is there.
Further, in the antenna structure disclosed in Patent Document 4, it is difficult to realize a small tag having an antenna size or less. Furthermore, since the IC chip is mounted on the antenna, the IC chip may be destroyed by an external electric shock such as static electricity or surge current. In addition, even if the IC chip portion installed in the direction of electromagnetic wave radiation is covered with a resin or the like, it is easily exposed to the outside by a cleaning operation with high-pressure jet water or the like, so there is a problem in electrical and mechanical strength. .

  Furthermore, the tag for electromagnetic wave radiation disclosed in Patent Document 5 is configured such that the plane of the IC chip and the plane of the band-shaped minute loop antenna electrically connected to the IC chip are parallel to the conductor surface to be attached. . In other words, the width of the band-like minute loop antenna is larger than the plane size of the IC chip. In such a configuration, there is a problem that attachment to the end portion of the sheet metal narrower than the width of the IC chip or the minute loop antenna is impossible. For this reason, it is difficult to realize a metal-compatible tag that is smaller than the size of a minute loop antenna wound around a base material such as a dielectric or magnetic material. Further, since the IC chip is electrically connected to the minute loop antenna, the IC chip may be destroyed by an external electric shock such as static electricity or surge current. In addition, there are cases where the IC chip part installed in the direction of electromagnetic wave radiation is covered with resin, etc., but it is easily exposed to the outside by cleaning work with high-pressure jet water etc., so there is a problem in electrical and mechanical strength. is there.

As described above, in the examples of Patent Documents 2 to 5, when the IC chip portion of the RFID tag is installed in the direction of electromagnetic wave radiation and is not protected by a metal plate or the like, it is attached to the metal surface as an RFID tag. There is a problem that the protection strength of the IC chip portion is inferior in high-pressure jet cleaning and sandblasting operations such as foreign matter removal and rust removal.
In addition, a small RFID tag may be installed at a place where it is difficult for communication electromagnetic waves to reach, such as a shadow of a screw head, a corner, a stepped portion, or a place where it is difficult to bring a reader / writer close.

An object of the present invention is to provide a small metal-compatible RFID tag that can be attached in a narrow range and a communication method therefor. In other words, an object of the present invention is to provide a method for realizing a small and narrow RFID tag that cannot be handled by the above-described conventional technology.
Furthermore, another object of the present invention is to secure mechanical strength such as impacts such as attachment to a narrow portion or the end of a thin sheet metal, and cleaning such as bending or high pressure jet water or rust removal work by sandblasting, It is an object of the present invention to provide a small metal-compatible RFID tag capable of maintaining a resistance to electric shocks such as surge current and static electricity.
Still another object of the present invention is a non-contact attachment type for a tag that is difficult to communicate without increasing the communication electromagnetic wave intensity of a normal reader / writer and without modifying the internal antenna of the reader / writer. It is an object of the present invention to provide an extended detection device and a communication method thereof that enable communication from a remote location via the detection device.

An example of a typical configuration of the present invention is as follows. That is, the RFID tag of the present invention includes an RFID tag body including an IC chip and a minute loop antenna connected to the IC chip, an arm that covers the IC chip via an insulating layer, and a loop surface of the minute loop antenna. A mounting surface for mounting the RFID tag body to the metal member in such a manner that the micro loop antenna includes the IC chip in the electromagnetic wave radiation direction at least once. The arm is connected to the minute loop antenna and extends in the winding direction of the loop by at least a length corresponding to approximately half of the loop so as to cover the IC chip. It is characterized by being.
According to another aspect of the present invention, an RFID tag includes an RFID tag main body including a micro loop antenna and an IC chip connected to the micro loop antenna, and a metal fitting for arranging the RFID tag main body inside. A mounting surface for mounting the RFID tag body to a metal member such that a loop surface of the micro loop antenna is substantially perpendicular to a mounting metal surface, and the micro loop antenna includes at least the IC chip. It is formed as a one-turn loop, and the metal fitting has an arm that extends in the winding direction of the loop and covers the IC chip so as to cover the IC chip on the loop in the electromagnetic wave radiation direction. In addition, a dielectric or magnetic material is filled between the inside of the loop of the micro loop antenna and between the metal fitting and the loop. Wherein the but has been formed.

According to another aspect of the present invention, the RFID tag is made of a slit-like matching circuit having a shape such as “L” or “T” to which an IC chip is connected and a metal plate or foil on which the matching circuit is mounted. A tag body having a shape in which a dipole antenna portion in an RFID inlet composed of a dipole antenna is cut out so that an IC chip and a matching circuit remain, and the IC chip connected to a high-frequency current so as to straddle the slit-like matching circuit The slit-shaped matching circuit is circulated from one electrode to the other electrode, and the slit-shaped matching circuit is also used as a minute loop antenna. And an upright holding portion configured to stand substantially perpendicular to the mounting metal surface.
According to another aspect of the present invention, a RFID tag body including a planar matching circuit micro loop antenna formed on a substrate and an IC chip connected to the micro loop antenna, and the RFID The tag main body includes an upright holding portion that holds the loop surface of the minute loop antenna substantially upright on the metal mounting surface.

  According to another aspect of the present invention, the RFID tag includes an RFID tag main body in which a micro loop antenna serving also as a matching circuit is integrally formed of the same semiconductor as the RFID logic circuit on the IC chip, and the IC chip on the IC chip. And an upright seat portion formed on the surface of the RFID tag main body so that the loop surface of the RFID tag body stands substantially perpendicular to the mounting metal surface.

  According to another aspect of the present invention, since any one of the RFID tags stands substantially perpendicular to the metal surface, a high-frequency current flowing through a minute loop antenna in the RFID tag on the metal surface, The high-frequency current that flows through the micro-loop antenna of the projected image is equivalent to an image that flows in the opposite direction to each other and flows in the same direction in the vertical part because of the image in the parallel part at the boundary of the metal surface. The micro loop antenna has a loop area twice as large as that of the micro loop antenna placed in free space and a non-metallic surface.

According to another feature of the invention, any one of the RFID tags and the attachment metal surface is directly coupled or indirectly electromagnetically coupled with an adhesive or the like, and a high-frequency current flows through the metal surface. As a result, the high-frequency current becomes a traveling wave with the frequency of the communication frequency as a period, propagates through the metal surface, and undulates the wave that interferes with the reflected wave returning from the discontinuous part in the propagation direction. The RFID tag is attached by emitting electromagnetic waves from interference waves that have nodules and the interval between the abdomen and the abdomen or the interval between the node and the node is an integral multiple of a half wavelength or a clear standing wave between the abdomen and the node. Communication is possible from directly above or away from directly above.
According to another feature of the present invention, an RFID tag installed in a place where communication is difficult can be communicated with a reader / writer using a non-contact externally attached detection instrument. In this detection instrument, a detection unit DT close to the tag side, a transmission unit T connected to the tag, and a re-radiation unit TR close to the reader / writer side and re-radiating electromagnetic waves are integrally provided.
Other features of the present invention will be described in detail in the detailed description.

  ADVANTAGE OF THE INVENTION According to this invention, the very small RFID tag which can be installed on a metal object, and its communication method can be provided. That is, according to the present invention, when the wavelength of the communication electromagnetic wave is λ, an RFID tag having a size of λ / 4 to an IC chip size can be realized.

In addition, according to the present invention, it is possible to realize a small-sized RFID tag capable of handling metal, which can maintain the resistance to electrical shocks such as surge current and static electricity while ensuring the mechanical resistance.
The RFID tag of the present invention is held so that the loop surface of the minute loop antenna is substantially perpendicular to the mounting metal surface. Alternatively, a slit matching circuit having a shape such as “L” or “T” is also used as a minute loop antenna. For this reason, if the loop surface of the micro loop antenna or the loop surface formed by the slit is installed so as to stand upright at 90 degrees on the metal surface to be attached, the loop surface of the image projected under the metal surface, that is, the image on the micro loop antenna. High-frequency current flows, but flows parallel to each other at the boundary of the metal surface, flows in the same direction at the part perpendicular to and below the metal surface, and is equivalent to a loop that is twice the free space It becomes a small loop antenna of area.
Further, by using a non-contact externally attached detection instrument, communication is possible even when the RFID tag is in a low sensitivity state due to embedding or narrow part installation.
Other effects of the present invention will be described in detail in the detailed description.

It is a perspective view which shows the example which installed the RFID tag which concerns on the 1st Embodiment of this invention on the metal object. It is a figure explaining the example which manufactures the RFID tag which becomes the 1st Embodiment of this invention using the inlet of RFID. It is a figure explaining the example of a manufacturing method of the "T" -shaped slit-shaped matching circuit of the RFID tag which becomes the 1st Embodiment of this invention. It is a figure explaining the example of a manufacturing method of the "L" -shaped slit-shaped matching circuit of the RFID tag which becomes the 1st Embodiment of this invention. It is a perspective view explaining an example of the structure of the RFID tag which becomes the 1st Embodiment of this invention. It is a perspective view explaining the other example of the structure of the RFID tag which becomes the 1st Embodiment of this invention. It is a figure which shows the relationship of the image RFID tag 70M when the RFID tag with the micro loop antenna 71 of 1 turn of winding which becomes the 1st Embodiment of this invention is installed in the metal surface. It is a figure explaining the equivalent circuit 71E of the micro loop antenna corresponding to FIG. 5A. It is a figure which shows the relationship of the image RFID tag 70M when the tag with the micro loop antenna 72 with the winding | turns number of turns which becomes the 1st Embodiment of this invention is installed in the metal surface. It is a figure explaining the equivalent circuit 72E of the 2-turn micro loop antenna corresponding to FIG. 6A. It is a figure explaining the attachment angle AG of the RFID tag which becomes the 1st Embodiment of this invention. It is explanatory drawing of the example which attached the RFID tag 70 to the metal surface 8 horizontally long. It is explanatory drawing of the example which attached the RFID tag 70 to the metal surface 8 vertically long. When the RFID tag according to the first embodiment of the present invention is installed on the metal surface 8, the traveling wave WF flows from the RFID tag 70, the reflected wave WR and the traveling wave WF interfere, and the interference wave W is generated. It is a figure explaining what arises. It is a perspective view explaining the RFID tag 70 corresponding to the metal made from all semiconductors comprised by the semiconductor manufacturing process which becomes the 2nd Embodiment of this invention. It is a figure explaining the RFID tag 70 made easy to attach to a metal surface as the 3rd Embodiment of this invention. It is a perspective view which shows the state which attached the RFID tag 70 which becomes the 3rd Embodiment of this invention to the level | step difference part etc. of metal. It is explanatory drawing of the method of embedding the RFID tag 70 which becomes the 3rd Embodiment of this invention in the metal hollow 81, a screw hole, etc. FIG. It is explanatory drawing of the RFID tag 70 which improved the mechanical strength as the 4th Embodiment of this invention. It is explanatory drawing of the RFID tag 70 which improved the mechanical strength as the 4th Embodiment of this invention. It is explanatory drawing of the RFID tag 70 which improved the mechanical strength as the 4th Embodiment of this invention. It is explanatory drawing of the RFID tag 70 which improved the mechanical strength as the 4th Embodiment of this invention. It is explanatory drawing of the structure of the RFID tag 70 which improved the electrical mechanical strength with the micro loop antenna formed from the strip | belt-shaped inlet as 4th Embodiment of this invention. It is explanatory drawing of the structure of the RFID tag 70 which improved the electrical mechanical strength with the micro loop antenna formed from the strip | belt-shaped inlet as 4th Embodiment of this invention. As an effect | action and effect of 4th Embodiment, it is explanatory drawing which protects IC chip 30 from surge electric current, welding current, electrostatic discharge current I, etc. with a protective metal fitting. It is a perspective view explaining that the area of the substantial micro loop antenna 71 is expanded and the sensitivity is improved by the protective metal fitting according to the fourth embodiment. It is sectional drawing explaining that the area of the substantial micro loop antenna 71 is expanded and the sensitivity is improved with the protective metal fitting which becomes 4th Embodiment. It is a figure of the example which improved the sensitivity with the metal fitting of the monopole antenna length which becomes 4th Embodiment. It is explanatory drawing of the example which improved the sensitivity by the metal fitting of the monopole antenna length which becomes 4th Embodiment. It is explanatory drawing of the example which improved the sensitivity by the metal fitting of the monopole antenna length which becomes 4th Embodiment. It is explanatory drawing of the example which improved the sensitivity by the metal fitting of the monopole antenna length which becomes 4th Embodiment. It is explanatory drawing of the example which improved the sensitivity by the metal fitting of the monopole antenna length which becomes 4th Embodiment. It is explanatory drawing of the example which improved the sensitivity by the metal fitting of the monopole antenna length which becomes 4th Embodiment. It is an example figure of the plane metal fitting which improved the sensitivity by the metal fitting surface structure which resonates to the monopole antenna length which becomes 4th Embodiment. It is explanatory drawing of the example which improved the sensitivity by the metal fitting of the dipole antenna length lambda / 2 which resonates to a half wavelength which becomes 4th Embodiment. It is explanatory drawing of the example which improved the sensitivity by the metal fitting of the dipole antenna length lambda / 2 which resonates to a half wavelength which becomes 4th Embodiment. It is explanatory drawing of the RFID tag using a pair of electromagnetic wave mode generation combined protection metal fitting 70SD7 which becomes 4th Embodiment. It is explanatory drawing of the RFID tag which uses the protection metal fitting 70SD8 for one half wavelength resonance / electromagnetic wave mode generation | occurrence | production which becomes 4th Embodiment. In the dipole antenna fitting 77 according to the fourth embodiment, the sensitivity is improved and the dimension is about twice as long. It is a figure explaining that an RFID tag can communicate from a distant place as a 5th embodiment of the present invention. It is a figure explaining that an RFID tag can communicate from a distant place as 5th Embodiment. As a fifth embodiment, a tag main body 60 is installed on the inner conductor of a coaxial cable or a coaxial tube C, and the RFID tag can communicate with each other on the outer conductor surface. FIG. 10 is a diagram for explaining that the high-frequency current i is made to flow positively through the conductors inside and outside the coaxial cable or the coaxial pipe C as a fifth embodiment. It is a figure of the use example which communicates with the RFID tag 70 of the location where the attachment type detection instrument D was recessed as 6th Embodiment of this invention. It is a figure of the use example as which it attaches to the RFID tag 70 with which the attachment type | formula detection instrument D was crowded as 6th Embodiment. It is a figure of the specific use example in the LF / HF band of the attachment type extension detection instrument DTR as 6th Embodiment. It is a figure of the specific use example in the UHF / microwave band of the attach-type extension detection instrument DTR as 6th Embodiment. It is a figure of the other specific use example in the UHF / microwave band of the attachment-type extension detection instrument DTR as 6th Embodiment. It is a figure of the other specific use example in the UHF / microwave band of the attachment-type extension detection instrument DTR as 6th Embodiment.

An RFID tag according to a typical embodiment of the present invention has an IC chip portion connected to a minute loop antenna placed in the direction of electromagnetic wave radiation placed directly under a metal arm such as a metal foil or a metal plate, and a loop of the minute loop antenna. In addition, a dielectric or magnetic filler layer is formed between the metal arm and the loop to enhance protection. The loop surface of the micro loop antenna is held so as to be substantially perpendicular to the mounting metal surface. When the wavelength of communication frequency of the RFID tag main body lambda, the loop diameter or length of the small loop antenna is about lambda / 10 or less, or loop area is lambda ^2/100 or less. Therefore, the formation method of the minute loop antenna may be changed depending on the frequency or wavelength of the radio wave used for communication.
For example, as a first example of a method for forming a micro loop antenna, it is used at a relatively low frequency such as a long wave or a short wave having a wavelength of several kilometers or several tens of meters. In the RFID tag having a size suitable for the above, since the necessary size of the micro loop antenna is already extremely small compared to the wavelength, the coiled RFID inlet itself is formed as a micro loop antenna.
As a second example of forming method, it is used at UHF with a wavelength of several tens of centimeters or several tens of centimeters, or at a high frequency in the microwave band. In the use of an RFID tag, a necessary method for forming a minute loop antenna can be formed by winding a strip-shaped RFID inlet based on a dipole antenna in a loop shape. For example, a part of at least one of the dipole antennas connected to the IC chip part at the center of the belt-like inlet is cut, and the belt-like RFID inlet is sized to the minute loop antenna so as to include the IC chip part, that is, the diameter. or lambda / 10 or less in length, or one-turn loop by loop area rounded to lambda ^2/100 or less is formed.
As a third example of the formation method, the different one-turn loop formation method is as follows: a slit-shaped matching circuit region connected to the IC chip portion of the UHF or microwave strip-like inlet is regarded as a micro loop antenna, and an IC chip. The matching circuit region may be cut out and formed as a single-turn micro loop antenna that also serves as a matching circuit.
Further, the loop is further continuously extended approximately half turn through an insulating layer such as a spacer between the one-turn loop formed by such a method and the IC portion on the loop in the electromagnetic wave radiation direction. Thus, an RFID tag with an arm is formed. The arm portion is provided with an electric strength for shielding the IC chip portion from static electricity and surge current. By making the extended portion of the arm substantially half-turned, or by using a strong metal arm, the mechanical strength is also improved. In addition, it cannot be overemphasized that the metal in this invention contains an alloy and an insulating layer is a layer insulated by direct current.
Each of the micro loop antenna forming methods described above has the following characteristics. First, in the case of the first method, since there is already a coiled inlet, there are few parts to be newly created. In this case, it is possible to easily realize that the coil surface, that is, the loop surface, is installed almost upright on the mounting metal surface and covered with the above-mentioned arm to protect the inside.
In the case of the second method, it can be easily realized by winding a strip-shaped inlet around a core material (medium or filler such as a dielectric or magnetic material) that becomes the core of the loop, and the above-mentioned arm portion is continuously provided. It has the characteristics that can be formed. Further, there is an advantage that the loop dimension can be freely changed in the process of winding the loop.
The third method has a process of rounding the strip-like inlet in the second method, but a small loop antenna can be formed so as to cut out the matching circuit part to which the IC chip part is connected. It has characteristics suitable for mass production that can be expected.
For example, RFID tags that are used at relatively low frequencies such as long waves and short waves with a wavelength of several kilometers or several tens of meters and that are suitable for users to grasp or pick when working, etc. Since the size of the loop antenna is already extremely small compared to the wavelength, the coiled RFID inlet itself is formed as a minute loop antenna.
On the other hand, several tens of cm Toka ten than about lambda / 10 having a wavelength of cm, or loop area is used in lambda ^2/100 or less in the UHF or high microwave band frequencies, the user grasps the work or the like, or In the use of an RFID tag having a size suitable for picking, a necessary method for forming a micro-loop antenna can be formed by winding a strip-shaped RFID inlet based on a dipole antenna in a loop shape. For example, by cutting a part of at least one of the dipole antennas connected to the central IC chip portion of the strip-shaped inlet and rounding the strip-shaped RFID inlet to the size of a micro loop antenna so as to include the IC chip portion, diameter or the lambda / 10 or less in length, or loop area lambda ^2/100 following one-turn loop is formed.
As a different method of forming a one-turn loop, the slit-shaped matching circuit area connected to the IC chip part of the UHF or microwave band inlet is regarded as a micro loop antenna, and the matching circuit area is cut out from the IC chip part and the matching circuit area. It may be formed as a combined single-turn loop micro loop antenna.
Further, the loop is further continuously extended approximately half turn through an insulating layer such as a spacer between the one-turn loop formed by such a method and the IC portion on the loop in the electromagnetic wave radiation direction. Thus, an RFID tag with an arm is formed. The arm portion is provided with an electric strength for shielding the IC chip portion from static electricity and surge current. By making the extended portion of the arm substantially half-turned, or by using a strong metal arm, the mechanical strength is also improved. In addition, it cannot be overemphasized that the metal in this invention contains an alloy and an insulating layer says the layer insulated by direct current.
Hereinafter, an RFID tag and a communication method thereof according to an embodiment of the present invention will be described in detail with reference to the drawings.

As a first embodiment of the present invention, the structure and operation of an RFID tag will be described. The RFID tag of the present embodiment is suitable for an application in which the RFID tag is installed and operated on a conductor surface or a metal surface (hereinafter referred to as a metal surface or a metal object).
FIG. 1 is a perspective view showing an example in which the RFID tag according to the first embodiment of the present invention is installed on a metal object.
The RFID tag 70 according to the first embodiment includes a tag body 60 and an upright holding unit 50. The tag body 60 is connected to a planar micro loop antenna 71 formed of a conductive material such as a metal plate or a metal foil on the substrate 5 and a pair of electrodes 31a and 31b to the micro loop antenna. And an IC chip 30. Inside the minute loop antenna 71, there is formed a slit-shaped matching circuit 20 that opens in a direction orthogonal to the antenna plane and has an impedance matching function between the IC chip 30 and the minute loop antenna. The IC chip 30 includes an integrated circuit including a rectifier and a microprocessor. The slit shape matching circuit 20 is obtained by providing an opening in a base material, for example, a laminate film. As described above, in this embodiment, the minute loop antenna 71 is a minute loop antenna that also serves as the matching circuit 20 and also serves as the matching circuit 20.
When the wavelength of the communication frequency is lambda, the loop diameter or loop length of the small loop antenna 71 (long side) is, lambda / 10 or less, or desirably loop area and lambda ^2/100 or less. The micro loop antenna is extremely thin, for example, about 20 μm thick, and the mechanical strength of the tag body 60 is secured by the base material 5.
The upright holding unit 50 sets the minute loop antenna 71 on the metal surface 8 so that the antenna plane (loop surface) of such a thin film is substantially perpendicular to the metal surface 8, thereby making the matching circuit 20 a high frequency. It has a function to prevent short circuit. The upright holding portion 50 has a flat seat surface 51 (51A, 51B, 51C) made of the same material as that of the minute loop antenna 71. For example, among the four sides when the rectangular minute loop antenna 71 is used, Three portions are formed so as to be orthogonal to any of the remaining three sides excluding the side on which the IC chip 30 is mounted. However, it is not always necessary to provide them in all of these three sides, and it is sufficient that they are formed in at least one place. In FIG. 1, the attachment angle AG is 90 degrees, that is, the loop surface of the minute loop antenna stands perpendicular to the metal surface 8 to be attached, but may be slightly inclined. That is, the angle AG formed by the seating surface 51 of the upright holding unit 50 and the minute loop antenna 71 may be in a range of 90 ° ± 30 ° (substantially perpendicular) as will be described later.
The material of the minute loop antenna 71 is not limited to metal, and may be a conductor made of a non-metallic material such as carbon, or a semiconductor. The slit shape of the RFID tag 70 is not limited to a shape in which the tag main body 60 and the upright holding unit 50 are combined in an L shape. For example, the slit shape may be T-shaped, or the entire outer shape may be a rectangular parallelepiped shape, and it is more convenient if the shape serves as an impedance matching circuit between the IC chip 30 and the minute loop antenna 71. is there.

Next, an example in which the RFID tag 70 according to the first embodiment of the present invention is manufactured using the RFID inlet 6 will be described with reference to FIG. 2 (FIGS. 2A and 2B).
FIG. 2A is a diagram illustrating the RFID inlet 6 including the dipole antenna 1 suitable for producing the RFID tag 70 according to the embodiment of the present invention. The RFID inlet 6 is obtained by forming a dipole antenna 1 having a thickness of, for example, about 10 μm to 20 μm on a base material 5 using a metal plate such as aluminum or a metal foil. FIG. 2A shows the positional relationship between the electrodes 31A and 31b to which the IC chip 30 is connected and the slit matching circuit 20. A matching circuit region 4 indicated by a broken line is cut out from the RFID inlet 6 having a substantially ½ wavelength.
Next, as shown in FIG. 2B, when the RFID inlet 6 cut out in the matching circuit region 4 is in electrical contact with the mounting metal surface 8 at the position indicated by the broken line BB, the surface of the conductive material is on the outside. In the case of electromagnetic contact with the mounting metal surface 8 through an insulating base material, the tag body 60 and the tag main body 60 are each bent so that the surface of the conductive material is positioned on the inner side. An upright holding unit 50 that holds the tag body 60 vertically is provided. The tag main body 60 functions as a metal-compatible RFID tag 70 when the attachment angle AG is substantially perpendicular to the metal surface 8, in other words, when the attachment angle AG of the minute loop antenna 71 is substantially perpendicular. That is, by holding the tag body 60 vertically, the matching circuit 20 can be prevented from being short-circuited in a high frequency when it is installed on the metal surface 8. In other words, the surface of the seat portion 51 is a surface of the same conductive material as that of the minute loop antenna, and the seat portion 51 does not need to be formed of an insulating member.
The upright holding portion 50 may be attached in contact with the metal surface 8 if the attachment angle AG of the tag body 60 is substantially a right angle.

Next, the slit matching circuit 20 of the RFID tag 60 according to the first embodiment of the present invention will be described with reference to FIG. 3 (FIGS. 3A and 3B). The slit matching circuit 20 has various shapes. For example, when the “T” -shaped slit-shaped matching circuit 20T in the RFID inlet 6 as shown in FIG. A tag body 60 having a slit-shaped matching circuit is formed.
Further, when the portion of the slit-shaped matching circuit 20L having the “L” shape in the RFID inlet 6 as shown in FIG. 3B is cut by the cut line 611, the tag having the slit-shaped matching circuit having the “L” shape. A main body 60 is formed.

  In this manner, the matching circuit region 4 is cut out from the RFID inlet 6 to form the tag main body 60, and the lower part of the matching circuit region is processed into an upright holding portion 50 that makes it easy to stand upright on the metal surface. 4 (4A, 4B) as shown in RFID tag 70 is obtained. The example of FIG. 4A has a “T” -shaped slit shape matching circuit 20T, and the example of FIG. 4B has an L ”-shaped slit shape matching circuit 20L.

  In the RFID tag 70 of this embodiment, a matching circuit having a shape such as “L” or “T” is provided also as a minute loop antenna 71 (a minute loop antenna also serving as a matching circuit). The loop surface formed by the slit of the inlet 6 is installed so as to stand upright at approximately 90 degrees on the metal surface to be attached.

FIG. 5 (FIG. 5A, FIG. 5B) is a figure explaining the effect | action and effect of the RFID tag 70 of a present Example provided with the micro loop antenna 71 with one winding. FIG. 5A is an explanatory diagram of the relationship between the image RFID tag 70M when the RFID tag 70 with a micro-loop antenna having one winding is installed on a metal surface, that is, addition of a real image and a virtual image. In the RFID tag 70 placed on the metal surface 8 and the image RFID tag 70M formed by projecting the same, the high-frequency current i flowing therethrough flows in the same direction in the vertical part of the metal surface 8 in the direction to cancel out at the boundary surface.
FIG. 5B shows that the loop area of the RFID tag 70 of FIG. 5A when the number of loop turns is one is twice the loop area formed by canceling the high-frequency current i at the portion having the metal surface 8 as a boundary, that is, the loop surface A1. And the equivalent area of the minute loop antenna equivalent circuit 71E having the total area of the image loop plane AM.

FIG. 6 (FIGS. 6A and 6B) is a diagram for explaining the operation and effect of the RFID tag 70 of this embodiment provided with the micro loop antenna 72 having two turns. FIG. 6A shows the relationship between the RFID tag 70 placed on the metal surface 8 and the image RFID tag 70M formed by projecting the RFID tag 70 in the case of the two-turn micro-loop antenna 72. It is shown that the current flows in the same direction at the vertical portion of the metal surface 8 in the direction canceled by.
FIG. 6B shows that the loop area of the RFID tag 70 when the number of loop turns is two is twice the loop area that the high-frequency current i cancels out at the portion having the metal surface 8 as a boundary, that is, the loop surfaces A1 and AM. It is explained that it is equivalent to an equivalent circuit 72E of a two-turn micro-loop antenna having a total area.
As described above, since the RFID tag 70 of this embodiment stands the RFID tag substantially perpendicular to the metal surface, the high frequency current flowing through the minute loop antenna in the RFID tag on the metal surface is projected below the metal surface. The high-frequency currents that flow through the micro-loop antenna of the image that can be generated flow in opposite directions because of the image in the parallel part at the boundary of the metal surface, and flow in the same direction in the vertical part. Therefore, it becomes a minute loop antenna equivalently having a loop area twice as large, and can be improved more than the sensitivity of the minute loop antenna placed in free space and a non-metallic surface.

  The example of FIG. 6 shows a case where the number of windings is two, but it may be 1.5, 3, or any number. In FIG. 6, it is representatively represented by two windings. In general, the higher the frequency, the lower the number of turns to reduce the high frequency loss. In UHF and microwaves, the number of turns is about once.

Here, the radiation power from the micro loop antenna is P, the wavelength of the communication electromagnetic wave is λ, the number of turns of the micro loop antenna is N, the area of the micro loop antenna is A, the high frequency current flowing through the loop is i, the circularity is π Then, Non-Patent Document 2 “Commentary: Basics of Antenna” p. From 42,
P = {20 · (2π / λ) ⁴ · (N · A) ² } · i ² (W)
Indicated by
It can be seen that P is proportional to the square of the product of the number of turns N and area A.
Therefore, when N = 1, when A is doubled, P is quadrupled, and the sensitivity of the one-turn micro-loop antenna is placed on the conductor surface or metal surface rather than on free space or non-conductor surface. At the same time, the image reflection can be used to greatly improve.
Non-Patent Document 2 “Fundamentals of antennas”, author Iwai Rikuji, publisher, Tokyo Denki University Press, November 25, 1967

As a verification of the fourfold sensitivity effect, a sample tag using an RFID inlet having a minute loop antenna is prepared.
The inlet is an RKT102 type manufactured by Hitachi, Ltd., which is wound once on a foamed polystyrene material having a thickness of 4 mm as a base material and a rectangular loop having a short side of 5 mm and a long side of 10 mm. At this time, the IC chip part is arranged at the central part of the long side 10 mm. This realizes a sample tag tag for verification provided with a micro loop antenna whose short side is approximately 1/20 wavelength of the communication frequency wavelength and whose long side is 1/10 wavelength.
The reader is R001M manufactured by Seconic Co., Ltd., which performs flight distance measurement.
The verification is that the distance when a sample tag is placed in the center of an aluminum plate with a square of 200 mm on one side and a thickness of 0.5 mm as a metal plate is the center of a rubber plate with a square of 200 mm on one side and a thickness of 8 mm as a non-metal plate. This is done by finding the multiple of the flight distance when the sample tag is placed.
First, a flight distance of 22 mm was obtained when the sample tag was placed on an aluminum plate.
Next, a flying distance of 6 mm when the sample tag was placed on the rubber plate was obtained. (Measurement Example 1)
Therefore, the flight distance ratio is about 3.7 times, and a value close to the theoretical value of 4 times is obtained.
In measurement, although the sample tag is linearly polarized and the reader is circularly polarized, there is a large sensitivity difference in the vicinity of the tag depending on the installation direction of the sample tag. Therefore, the sample tag is installed in the direction of 45 degrees, which is intermediate between the horizontal polarization and the vertical polarization.
For ease of explanation, horizontal or vertical polarization is defined as vertical polarization on the reader antenna surface and horizontal polarization on the horizontal side.

It has also been confirmed that the maximum flight distance is obtained when the loop surface of the micro loop antenna is at an angle of 90 degrees with respect to the metal surface.
As a confirmation method, first, the sample tag uses the same RFID inlet as in the above-mentioned measurement example 1, and this is used as a base material with dimensions of 2 mm in width and 10 mm on one side of 10 mm square foamed polystyrene material. Make a sample tag by winding it once in a square loop along the side.
Next, the same metal plate and reader as those in Measurement Example 1 are used for this sample tag, and the flight distance is measured on the metal plate for each intersection angle of the loop surface. The polarization plane is measured for the flight distance when the reader sensitivity is higher (measurement example 2).
When the angle with the sample tag is 0, this corresponds to the case of flat placement. At this time, the tag does not respond, that is, it is confirmed that the tag does not operate as a metal-compatible tag. The distance is 10mm, 30mm when the angle with the sample tag is 60 or 120 degrees, and 40mm when the angle with the sample tag is 90 degrees. This means that the distance is upright on the metal surface. I have confirmed.

FIG. 7 shows a summary of the measurement results, that is, the relationship between the mounting angle AG and the flight distance. From FIG. 7, it can be seen that 80% of the peak sensitivity is in the range of ± 30 degrees centering on 90 degrees. That is, it is desirable that the angle AG formed by the seating surface 51 of the upright holding unit 50 with the minute loop antenna 71 is in the range of 90 degrees ± 30 degrees (substantially perpendicular).
Furthermore, instead of the foamed polystyrene material used in Measurement Example 1, a small micro-loop antenna is used instead of a rubber magnet sample tag with a thickness of 3 mm, width of 4 mm, and length of 6 mm, and a metal-compatible RFID tag can be realized. I have confirmed. Even when the length is further reduced to 3 mm, it is confirmed that a normal RFID reader / writer can be realized, and, for example, a metal-compatible RFID tag that can be communicated with an R001M reader manufactured by Seconic Corporation can be realized. It has been confirmed that the sample tag operates even when the thickness is 0.4 mm, the width is 4 mm, and the length is about 10 mm (measurement example 3).
These agree with the suggestion that radiation is performed as long as the area is not zero, without depending on the shape of the loop surface, from the formula representing the radiated power.

The RFID tag of this embodiment can be used by being electromagnetically coupled directly to the mounting metal surface with a direct coupling or an adhesive.
FIG. 8 (FIG. 8A, FIG. 8B) is explanatory drawing of the example which attached the RFID tag 70 of a present Example to the metal surface 8 directly horizontally or vertically, respectively.
For example, the RFID tag of this embodiment is electrically connected to the mounting metal surface 8 by direct coupling as shown in FIG. 8 or capacitively electromagnetically coupled to the metal surface 8 by indirect coupling via an insulator. Thus, communication can be performed from directly above or away from the directly attached RFID tag 70.

That is, as shown in FIG. 9, a high-frequency current i flows from the RFID tag 70 attached to the metal surface 8 to the left and right on the metal surface 8, and the reflected wave WR generated at the end portion The traveling wave WF interferes to generate an interference wave W having a half wavelength period WL that undulates every half wavelength.
FIG. 9 shows that the metal surface 8 has a clear node WV and an abdomen WP with an integral multiple of ½ wavelength, but when the length is an arbitrary length of ½ wavelength or more, the node WV and the abdomen are shown. Interference wave W that makes WP unclear. At this time, electromagnetic radiation into the air also decreases. The situation of the interference wave W having such an arbitrary length is not shown.
As described above, when the RFID tag is electromagnetically coupled to the metal surface, a high-frequency current flows through the metal surface, and the high-frequency current becomes a traveling wave having a period of the communication frequency as a period, propagates through the metal surface, and is a discontinuous portion in the propagation direction. Interfering waves and abdomen, which have a high-abdominal abdomen and a low-wave node, which are swells of the waves that interfere with the reflected wave returning at, and the interval between the abdomen and abdomen or between the node and the node is a period that is an integral multiple of a half wavelength Electromagnetic waves are radiated from a clear standing wave at the node, and communication is possible from a location directly above or away from the top of the attached RFID tag.
According to the present invention, since the RFID tag is configured such that the loop surface of the very thin matching loop also used as a matching circuit is held substantially upright by the upright holding portion, the extremely small RFID that can be installed on a metal object Can provide tags. That is, according to the present invention, when the wavelength of the communication electromagnetic wave is λ, an RFID tag having a size of λ / 4 to an IC chip size, for example, 0.3 mm or less can be realized.

Next, a second embodiment of the present invention will be described. The shape and manufacturing method of the RFID tag of the present invention are not limited to the configuration and method shown in the first embodiment. In the present embodiment, the manufacturing method of the RFID tag 70 is characterized in that a matching circuit also used as a micro loop antenna is integrated on an IC chip and integrated with a semiconductor.
That is, as shown in FIG. 10, a metal-compatible tag can be formed using a semiconductor. In this case, the minute loop antenna pattern 71S and the matching circuit 20S are combined.
That is, a substantially rectangular parallelepiped RFID tag main body 60 in which a pattern of a micro loop antenna and matching circuit is formed by a semiconductor manufacturing process on the same semiconductor substrate directly connected to a pattern of an IC logic circuit 31 such as an ID; A side surface as an upright support portion 50 formed on the surface of the RFID tag body such that the loop surface on the IC chip stands substantially perpendicular to the mounting metal surface 8, that is, an upright seat portion 51 (in the figure, three surfaces 51A, 51A, 51B, 51C) can be obtained as a semiconductor chip level RFID tag 70. According to the present embodiment, when the wavelength of the communication electromagnetic wave is λ, an RFID tag having a size from λ / 4 to an IC chip size can be realized. In addition, the upright support part 50 can ensure an area and mechanical strength required as an upright seat part by thickening the thickness of a semiconductor substrate, ie, the base material 5, for example.

According to this embodiment, it is possible to provide a small RFID that can be installed on a metal object only by a semiconductor manufacturing process.
In the RFID tag of this embodiment, the matching circuit 20S is also used as the minute loop antenna 71S. When this RFID tag 70 is installed so as to stand upright at 90 degrees on the metal surface to which the loop surface is attached, a high-frequency current of the image flows through the loop surface of the image projected under the metal surface, that is, the minute loop antenna. In the parallel part at the boundary of the metal surface, it flows so as to cancel each other, in the part perpendicular to the metal surface and in the same direction, it flows in the same direction, and a minute loop antenna having a loop area equivalent to twice the free space Become.

Next, as a third embodiment of the present invention, an RFID tag 70 that is easily attached to a metal surface will be described with reference to FIG.
In the present embodiment, the RFID tag 70 is a strong dielectric with low loss at high frequency in order to protect the IC chip and the matching circuit against external impact and pressure, or to improve the convenience of mounting. It is easy to handle and attach and is mechanically reinforced with resin, ceramics, insulating adhesives, etc., and magnetic materials or mixed materials thereof. Also in the present embodiment, the RFID tag 70 can be used by being electromagnetically coupled directly to the mounting metal surface with a direct coupling or an adhesive.
That is, as shown in FIG. 11, the RFID tag 70 is made strong by being covered with a dielectric or magnetic filler 70C and is easily attached to the metal surface 8 with a stopper 70B such as a screw. is there. In this case, the stopper may be a metal screw or an insulating resin. In the case of a metal screw, an effect as an inductive or capacitive post that draws the high-frequency current i may be expected. Therefore, the sensitivity can be improved by adjusting the length and position.

  In the example of FIG. 12, the RFID tag 70 can be easily attached to the stepped portion of the metal surface 8 using an adhesive 70D or the like. The high-frequency current i flows on the surface of the stepped portion and operates through the IC chip 30 of the RFID tag 70 in the middle of the path.

The example of FIG. 13 shows a mounting method embedded in a metal depression 81 or a screw hole. That is, the tag main body 60 can be embedded, fixed with the adhesive 70D, etc., and attached without protruding from the surface of the metal surface 8.
As described above, since the RFID tag according to the present invention is small in size, it can be attached to the step of a metal plate by a strong object such as a stepped portion, a depression, a corner portion, or a shadow of a convex portion such as a screw head. There is an advantage that a special protective metal fitting can be omitted or a concave cutting operation for mounting can be omitted, and the mounting work burden can be reduced.

Next, as a fourth embodiment of the present invention, an RFID tag 70 in which the mechanical strength of the micro loop antenna is improved by the RFID tag protective metal fitting will be described. In the present embodiment, with respect to the minute loop antenna of the RFID tag main body 60, the loop surface is held substantially upright on the metal mounting surface.
As a method for forming a micro loop antenna in the present embodiment, as described in the first and second embodiments, the region of the matching circuit 20 of the RFID inlet 6 is cut out and made substantially upright on the mounting metal surface 8. . In this case, the slit of the matching circuit takes on the function of a minute loop antenna and plays a role of combining two functions. In another method of forming a micro loop antenna, instead of cutting out the matching circuit 20, the RFID inlet is cut to a predetermined length including an IC chip, and this is wound at least once to create a new micro loop antenna. Is substantially upright on the mounting metal surface 8. A method of newly creating a micro loop antenna from the RFID inlet will be described in detail later. Regardless of which means is used, the micro loop antenna alone cannot be said to have sufficient mechanical strength. Therefore, as described below, it is desirable to adopt a system in which the micro loop antenna is held inside.

The RFID tag of this embodiment is arranged inside a metal fitting of a shield structure such as a shell structure, a folded structure, or a folded terminal structure for the purpose of protecting the IC chip against an external electric shock such as static electricity or surge current, At least the IC chip 30 and the matching circuit 20 are shielded against electrical shock by a protective metal fitting electromagnetically coupled through an insulating spacer so as not to short-circuit. The spacer 61S may be air or a dielectric or magnetic filler 70C. Usually, it is preferable that the spacer 61S and the filler 70C are integrally formed of the same material made of a dielectric or magnetic material.
In the fourth embodiment, the shape of the protective fitting of the RFID tag 70 is the shell structure protective fitting 70SD1 of FIG. 14A, the folded structure protective fitting 70SD2 of FIG. 14B, the folded terminal structure protective fitting 70SD3 of FIG. 14C, and the terminal structure of FIG. There are examples such as the protective metal fitting 70SD4, and each can improve the mechanical strength. In each figure, the spacer 61S is a separator for preventing the matching circuit of the tag body 60 formed of a dielectric material or a magnetic material from being short-circuited with the protective fitting.

FIG. 14E is an explanatory diagram of a structure of the RFID tag 70 in which the protective metal fitting 70A of the RFID tag 70 is formed integrally with the minute loop antenna. This example is an RFID tag suitable for an application in which UHF or microwave frequency is used. 14E is a perspective view, and FIG. 14B is an enlarged view of the vicinity of the IC chip 30, in which the slit matching circuit 20 is arranged in parallel to the metal surface 8. (C) is a longitudinal cross-sectional view of (a).
First, since the slit shape matching circuit 20 of the RFID tag 70 in this example is parallel to the protective metal fitting 70A via the metal surface 8 or the spacer 61S to be attached, it cannot have a function of a minute loop antenna. Therefore, the strip-shaped RFID inlet 6 including the IC chip 30 is wound at least once so as to function as the minute loop antenna 71, and a part of the loop surface of the minute loop antenna 71, that is, the side where the IC chip 30 is disposed. By making the edge (side) of the loop on the opposite side to the seat or the attachment surface 51, it is configured to be substantially upright on the metal surface 8 to be attached. 70C is a dielectric or magnetic filler. The RFID tag 70 of this example cuts the strip-shaped RFID inlet 6 into a predetermined length including the IC unit 30 with an RFID inlet based on, for example, a UHF or microwave band dipole antenna. A loop of one turn is formed using the filler 70C as a core material and wrapping around the dimensions of the minute loop antenna 71.
In this example, the minute loop antenna of the RFID tag 70 is formed integrally with the protective metal fitting (arm) 70A. For example, an RFID inlet 6 having electrodes 31a and 31b to which an IC chip 30 is connected and a slit matching circuit 20 as shown in FIG. 2A is used. However, unlike the matching loop micro loop antenna shown in FIG. 2A, the both ends of the RFID inlet 6 are bent without being cut to form a one-turn loop micro loop antenna 71. In this case, the matching circuit 20 is substantially parallel to the metal surface 8 to be attached, and the minute loop antenna 71 is substantially upright. The matching circuit 20 has a slit shape such as an “L” shape or a “T” shape. That is, the strip-shaped RFID inlet 6 is wound once so that the IC chip 30 is included in the dimension of the minute loop antenna 71, and the protective metal fitting is integrally formed. At this time, in the connection point region 72C where the start point and the end point corresponding to one turn of one loop of the minute loop antenna 71 are connected, the connection is performed by either direct connection or indirect connection electromagnetic coupling. In addition, a protective metal fitting, that is, an arm 70A is provided on the upper side of the IC portion 30 on the loop in the radio wave radiation direction, with the RFID inlet being further continuously wound half a turn from the connection point 72C while being insulated through the spacer portion 61S. Let it be an RFID tag. For example, an end 70 </ b> A of the RFID inlet 6 is further extended by approximately a half turn to form an arm 70 </ b> A that covers the tag main body 60, thereby forming the RFID tag 70. In the RFID tag 70 of this example, the length of the portion parallel to the metal surface 8 of the minute loop antenna 71 in one turn of the loop is about λ / 10, or the area inside the loop of one turn is λ ^2. / 100 or less is desirable. On the other hand, the lower limit value of the loop size is determined according to the size of the IC chip 30 included in the loop. The length of the arm 70A may be extended to λ / 4. By providing the arm 70A, the RFID tag 70 can have a resistance (static shielding) against static electricity and surge current, and sensitivity can be increased. Furthermore, the mechanical strength can be improved at the same time by making the arm 70A a strong metal material.

FIG. 14F is an explanatory diagram of a structure of an RFID tag 70 as another example including a protective metal fitting. As in the example of FIG. 14E, the RFID tag 70 of this example has a loop surface wound around the band-shaped RFID inlet 6 at least once so as to function as a minute loop antenna so that the mounting metal surface 8 is substantially upright. It is configured. In the example of FIG. 14E, the arm 70A is composed of the tag main body 60 and a series of strip-like RFID inlets, whereas the example of FIG. 14F is the portion of the tag main body 60 provided with the minute loop antenna 71, that is, the number of loop turns. The one-time portion is separated from the protective metal fitting, that is, the arm 70A and is independent. 14A is a perspective view, FIG. 14B is an enlarged view of the tag main body 60 of FIG. 14A, and FIG. 14C is a longitudinal sectional view of FIG. The metal arm 70A functions as a folded structure protective metal fitting 70SD2. The loop surface is configured to be substantially upright on the mounting metal surface 8 by setting the side opposite to the metal arm 70A of the folded structure protection metal fitting 70SD2 across the tag body 60 as a seat or mounting surface 51. . In this example as well, the RFID tag 70 can be made resistant to static electricity and surge current (electrostatic shielding) to increase the sensitivity, and the arm 70A is made of a strong metal material, so that the mechanical strength is also improved. It can be improved at the same time.
In the RFID tag 70 of this example, the tag main body 60 is apparent from the relational expression of the radiated power, the number of turns N and the area A of the micro loop antenna shown in Non-Patent Document 2, and FIGS. 16A and 16B described later. This corresponds to the tag main body 60 regarded as a minute loop antenna obtained by cutting out and guiding the slit-shaped matching circuit described in the present invention. Therefore, it is the same as the equivalent circuit described in FIG. 5B, and can be regarded as an equivalent that cannot be distinguished from the example of FIG. Accordingly, the examples of FIGS. 14E and 14F are also installed in various protective fittings such as the shell structure protective fitting 70SD1, the folded structure protective fitting 70SD2, the folded terminal structure protective fitting 70SD3, and the terminal structure protective fitting 70SD4 shown in FIGS. 14A to 14D. Therefore, the same operation as that performed can be performed, and the same effect can be obtained. For each of the embodiments described below, the same effect can be obtained by employing the band-shaped minute loop antenna shown in FIGS. 14E and 14F.

The operation and effect of the fourth embodiment will be described with reference to FIG. In each example of the fourth embodiment, the protective metal fittings protect the IC chip 30 inside the tag body 60 from electrical shock by discharging surge current, welding current, electrostatic discharge current I, and the like to the metal surface 8. FIG. 15 shows an example in which the RFID tag 70SD2 is protected by a folded structure protective metal fitting.
As described above, the RFID tag according to the present embodiment is used to protect the IC chip from external electric shocks such as static electricity and surge current, and to protect the inside of the metal shell having a shield structure such as a shell structure, a folded structure, or a folded terminal structure. In addition to realizing an RFID tag that is shielded against electrical shock by a protective metal fitting that is electromagnetically coupled through a spacer so that at least the matching circuit is not short-circuited, a screw hole is provided in the protective metal fitting to help prevent falling off.
In addition, as a strength verification against high static electricity voltage and surge current, high voltage generated by igniting equipment with piezoelectric elements is directly discharged in the air to the RFID tag with folded terminal structure protected by shield structure. I have confirmed that.
Further, it has been confirmed that even when welding with an electric current of about 100 A to an RFID tag having a folded terminal structure protected by a shield structure with an electric welding machine as a large current, it is confirmed that the device is operating normally.

As another example of the present embodiment, the RFID tag protective metal fitting has a width of the antenna conductor of the minute loop antenna of the RFID tag to be protected, so that the substantial minute loop antenna area is a loop excluding the antenna conductor portion. However, since the protective bracket is outside the micro loop antenna, high frequency magnetic flux is guided to the loop from the outside to increase the actual micro loop antenna area to the position where the protective bracket surrounds and improve the sensitivity. In addition, a shield structure such as a shell structure, a folded structure, or a folded terminal structure improves mechanical strength and resistance to electrical shock.
That is, in the example of FIG. 16 (FIG. 16A, FIG. 16B), the area of the micro loop antenna 71 is substantially enlarged by the protective metal fitting to improve the sensitivity.
First, FIG. 16A is a perspective view of an RFID tag with a protective metal fitting, and a cross section SS ′ of the protective metal fitting portion of FIG. 16A is shown in FIG. 16B (b). This is shown in (a) of FIG. 16B. A state in which high-frequency magnetic fluxes are induced in the loops around because they are outside the respective minute loop antennas 71 will be described. Here, (a) of FIG. 16B corresponds to the vertical dimension A0 of the loop surface without protective metal fittings to the high frequency magnetic flux Φ1 without protective metal fittings. When this is protected by the protective metal fitting 70SD2 of FIG. 16B, a high-frequency magnetic flux Φ2 with a large protective metal fitting is obtained, and as a result, the enlarged loop surface vertical dimension AS is obtained by the protective metal fitting. It explains that the area is enlarged and the sensitivity is improved.
Thus, in the metal-compatible RFID tag of this embodiment, the antenna conductor of the minute loop antenna of the RFID tag to be protected has a width, so that the substantial minute loop antenna area becomes the loop area excluding the antenna conductor portion. Because the protective bracket is outside the micro loop antenna, high frequency magnetic flux is guided from outside to the slit that is equivalent to the loop, so that the actual micro loop antenna area is expanded to the position where the protective bracket surrounds and the sensitivity is improved. In addition, a shield structure such as a shell structure, a folded structure, or a folded terminal structure can realize an RFID tag that improves mechanical strength and resistance to electrical shock.

As another example of the present embodiment, an example in which the sensitivity is improved by a metal pole with a monopole antenna length is shown in FIG. 17 (FIGS. 17A, 17B, 17C, 17D, 17E, 17F, FIG. 17G). In these examples, the protective bracket is configured with a 1 / 4-wavelength monopole antenna length in the electromagnetic wave medium to actively promote resonance, and even on a non-metal surface or on a metal surface. However, the sensitivity is improved so that communication is possible.
That is, in each example of FIG. 17, a shield structure metal fitting, that is, FIG. 17A is a shell structure protection metal fitting 70SD1, FIG. 17B is a folded structure protection metal fitting 70SD2, FIG. 17C is a folded terminal structure 70SD3, and FIG. Is a case of the RFID tag 70 in which the sensitivity is improved by using a bracket of a monopole antenna length of approximately λg / 4 in the medium. For example, stainless steel is used for the metal fitting.

Further, in the example of FIG. 17E, the metal arm 70A of the micro loop antenna 71 of FIG. 14E is continuously extended in the horizontal direction by E = λ _g / 4 or a length close to it (approximately λg / 4) from the connection point region 72C. The arm 70A has a shape that extends and covers the IC chip 30 from above. The side opposite to the metal arm 70 </ b> A across the tag main body 60 is a seat or mounting surface 51, so that the loop surface is substantially upright on the mounting metal surface 8.
Further, in the example of FIG. 17F, the upper and lower metal arms 70A of the minute loop antenna 71 of FIG. 14F are further horizontally moved from the connection point region 72C by E = λ _g / 4 or a length close thereto (approximately λg / 4). A shell-shaped protective metal fitting 70SD1 with an arm 70A that extends continuously and covers the IC chip 30 is provided.
Moreover, the example of FIG. 17G has shown the RFID tag 70 in which the surface pattern was provided with C-type plane protection metal fitting 70SD5. 17G, (a) is a perspective view of the RFID tag 70, and (b) is an aa ′ cross-sectional view of (a). The example of FIG. 17B has a convex protrusion, whereas in the example of FIG. 17G, the mounting hole 78 is formed in the metal fitting 70SD5 and the metal arm 70A having a structure that resonates mainly with the length of the monopole antenna in the medium is the same. The RFID tag 70 is formed in a flat surface and has a structure in which the protrusions are smoothed. The metal arm 70A extends continuously in the horizontal direction by λ _g / 4 or a length close to λ _g / 4 (approximately λg / 4) and covers the IC chip 30 from above. There is a C-shaped or U-shaped gap 79 around the metal arm 70A. The tag body 60 is mounted directly below the arm 70A (the optimum position is not necessarily the base position of the arm and may slightly deviate from the root when aligned) via the spacer 61S, and the IC chip 30 is a protective metal fitting. Arranged inside. In this example, the tag main body 60 has a cross-sectional configuration as shown in FIG.
Furthermore, in the example of FIG. 17G, when the entire length of the metal fitting 70SD5 is set to a length that resonates at a half wavelength, higher sensitivity can be realized even in free space or on a non-metal.

  In this way, in order to improve the sensitivity of the RFID tag 70, in addition to protective metal fittings typified by a shield structure such as a shell structure, a folded structure, or a folded terminal structure, a 1/4 wavelength long monochromatic wave in a communication electromagnetic wave medium is used. An RFID tag can be realized that has a protective metal fitting with a pole antenna length dimension, actively promotes resonance, and has improved sensitivity so that communication can be performed on a non-metal surface or a metal surface.

The RFID tag 70 of the present invention can be communicated with high sensitivity even if it is installed on a non-metal surface as well as on a metal surface. For example, the tag main body 60 is installed so as to be disposed at the feeding point of the dipole antenna by digging a depression or the like in the center of a metal plate having a length that resonates with a half wavelength of the communication electromagnetic wave. A dipole antenna-sized protective bracket formed by placing the tag body 60 at the feeding point of an antenna having a length of approximately half a wavelength formed by connecting two protective brackets of the same monopole antenna length Thus, it is possible to realize an RFID tag that actively promotes resonance and enables high-sensitivity communication on a non-metal surface or a metal surface.
The example of FIG. 18A is a diagram illustrating an example of an RFID tag 70 in which the size of the protective metal fitting is configured with a dipole antenna length λ / 2 that resonates at a half wavelength and sensitivity is improved.

  The example of FIG. 18B is an example of the RFID tag 70 provided with the H-shaped flat protective metal fitting 70SD6. 18A is a perspective view of the RFID tag 70, and FIG. 18B is a cross-sectional view taken along the line a-a 'of FIG. 18A. In the example of FIG. 17G, there is one metal arm 70A, whereas in the example of FIG. 18B, two metal arms 70A are opposed to each other and a gap 79 is provided so that the tips of both arms are not in contact with each other. have. That is, an “H” -shaped pattern with a gap 79 is formed on the surface of the dipole antenna fitting 77. A tag main body 60 is mounted via a spacer 61S directly below one of the arms 70A (the optimum position is determined by slightly shifting from the center to align the electromagnetic mode arm), and the IC chip 30 is a protective metal fitting. Arranged inside. For this reason, the tag main body 60 has a structure reinforced electrically and mechanically. Furthermore, since the overall length of the metal fitting 70SD6 is a half-wavelength, it is possible to realize the RFID tag 70 that can communicate with high sensitivity even when mounted on a non-metal surface including a free space or on a metal surface.

The example of FIG. 18C is an RFID tag 70 using a pair of electromagnetic wave mode generating / protecting metal fittings 70SD7. 18A is a perspective view, and FIG. 18B is a cross-sectional view along line aa ′ in FIG. 18A. In this example, two substantially circular metal plates (electromagnetic wave mode generation / protection metal fittings) 70SD7 are located approximately at the center (the optimum position is determined by slightly shifting from the center to match the electromagnetic wave mode) via the spacer 61S. The tag body 60 is sandwiched and fixed with a dielectric or magnetic filler 70C. When this RFID tag 70 is installed on the mounting metal surface 8 and communicates from above, a high-frequency current known from microwave theory flows on the outer surface and inner surface of the upper metal plate 70SD7. Current mode iTM is distributed. The best resonance condition for this current is that the wavelength inside 70C, that is, the wavelength in the medium is λg, the circumference is π, and the outer dimension of the metal plate is Di.
Di = (1.841 / π) λg
Given in. Here, 1.841 is an effective numerical value of 4 digits of the minimum root of the differential type first-order Bessel function.
In this example, the high frequency current resonating in the TM basic mode is electromagnetically coupled via the tag main body 60 and the spacer 61S, and functions as the RFID tag 70 integrated with the electromagnetic wave mode generating / protecting metal fitting 70SD7.
In (a) of FIG. 18C, an instantaneous state where the high-frequency current distribution is alternately switched is stopped and indicated by an arrow. Incidentally, the starting point of the arrow is the maximum potential portion of +, the destination end point of the arrow is the maximum potential portion of −, the center of the arrow is 0 potential (the 0 potential line in the figure), and at this time, the current becomes the maximum value simultaneously. The zero potential portion has little influence on the resonance state even if it passes through the small mounting hole 78 or screw.
Through the trial manufacture of the example of FIG. 18C, even when the planar shape of the metal plate is circular or square, when the RFID tag is configured, a difference in shape and a difference in sensitivity are found with a flight distance sensitivity of about one wavelength at most. It was confirmed that it was difficult. As one prototype example, the metal plate is replaced with a square having a side of 16 mm, the filling resin is made of a material having a relative dielectric constant of 20, the frequency is 2.45 GHz, and the tag body 60 is a muchip inlet (manufactured by Hitachi, Ltd.) RKT102). When this prototype RFID tag was installed on a sufficiently wide metal surface through two screws having a diameter of 3 mm at the 0 potential portion, the flight distance was measured with a reader R001M manufactured by Seconic Co., and a flight distance of about 100 mm was obtained. Furthermore, as another prototype, the metal disk is 71.5 mm in diameter and not screwed, the filler is air with a relative dielectric constant of 1, the same tag body as in the previous example, and the flying distance with the same reader R001M as in the previous example And a flight distance of 180 mm was obtained. As described above, the inventor confirmed the influence of the resonance of the TM fundamental mode and the zero potential by the prototype example.

In the example of FIG. 18C, two substantially circular metal plates (in FIG. 18C, the metal plate is the electromagnetic wave mode generating / protecting metal fitting 70SD7) are used. However, as shown in the example of FIG. Since the metal surface overlaps when the surface is attached, the lower metal plate may be omitted and only one electromagnetic wave mode generating / protecting metal fitting 70SD8 may be provided. Further, as shown in FIG. 18D, in order to easily resonate at a half wavelength in a free space, the two arms 70A are opposed so that the tips of the two arms 70A do not come into contact with each other so as to form an “H” shape. In this case, the tag body 60 may be fixed by a dielectric or magnetic filler 70C or an adhesive 70D via a spacer 61S at an optimal position at any point immediately below the arm). That is, the example of FIG. 18D is an RFID tag 70 in which the half-wave resonance / electromagnetic wave mode generation / protection metal fitting 70SD8 and the tag body 60 are integrated.
The feature of the tag of this example is not only that the entire thickness can be reduced by one metal plate, but also that the operation is possible in a free space other than the metal surface, for example. Further, as in the example of FIG. 18C, it is possible to provide a mounting hole 78 or a screw on the zero potential line. This is because the TM fundamental mode current iTM is distributed when it is placed on the mounting metal surface because there is only one metal plate, but the resonance of the TM fundamental mode becomes difficult in free space, but the metal plate outer dimension Di is half. Since the half-wave resonance current ID is not the maximum current because it is close to the wavelength resonance dimension, it functions as an RFID tag 70 with practically sufficient sensitivity.
The metal plate outer dimension Di of the TM basic mode is Di = (1.841 / π) · 122 to 71.5 mm where the communication wavelength is 122 mm, the medium is air, and the circumference is π. On the other hand, typical half-wave resonance dimensions in air are 122/2 to 61 mm. That is, the difference between these (the metal plate outer dimension Di and the general half-wave resonance dimension) is 17%.
For distance sensitivity of about one wavelength at most, Di is set to an intermediate dimension between them (in this case, the intermediate value is 66 mm, 9% difference), and it has a stable sensitivity from a metal surface to a non-metal surface, and a thin application range. A wide RFID tag 70 can be realized.

Further, by adopting the dipole antenna bracket 77, the sensitivity is improved, but the dimension is about twice as long.
FIG. 19 shows a structure in which, for example, two monopole antenna 75 fittings are connected back to back in order to improve sensitivity, and a dipole antenna fitting 77 having a full-length half-wavelength dimension in air can be formed. However, the dimensions are about twice as long as the dipole antenna.

  That is, when sensitivity is given priority, the size increases, but according to the present embodiment, a hollow is dug in the center of the metal plate having a length that resonates with a half wavelength of the communication electromagnetic wave, and is arranged at the feeding point of the dipole antenna. RFID tag at the feeding point of an antenna with a length of about half-wavelength, which can be installed by connecting two protective brackets of the length of a monopole antenna with a length of 1/4 wavelength back to back at the connection part A dipole antenna-sized protective metal fitting can be constructed by arranging the antenna, and it is possible to realize an RFID tag with improved sensitivity so that resonance can be actively promoted to enable communication on a non-metal surface or a metal surface. .

Next, as a fifth embodiment of the present invention, an example in which the RFID tag of the present invention is used to communicate from a remote location will be described with reference to FIGS. 20 (FIGS. 20A and 20B).
In this embodiment, the RFID tag according to any one of the above-described examples is arranged such that the longitudinal direction of the RFID tag is parallel to the wire and the slit surface inside the RFID tag is on the surface of the wire. Installed so as to be almost upright (Fig. 20A), or connected to the end of the metal rod by direct connection or electromagnetic coupling so as to extend the RFID tag (Fig. 20B). Waves with a high wave height and nodes with low wave heights, which are wave swells that propagate through the metal surface and interfere with reflected waves that return at discontinuities in the propagation direction, and are traveling waves with a frequency of frequency as a period. Alternatively, in the place where the distance between the node part and the node part is an integer multiple of a half wavelength, or electromagnetic waves are radiated from the clear standing wave of the abdomen and the node part, and directly above or just above the attached RFID tag Communication Wherein the ability and the RFID tag and its communication method of a shape that is integrated with a metal rod.
As shown in FIG. 20A, the tag body 60 is attached to the surface of the wire-like metal rod 9 so that the longitudinal direction of the tag body is parallel to the metal rod, and the interference wave of the high-frequency current i is attached to the surface of the wire-like metal rod 9. By generating electromagnetic waves and emitting electromagnetic waves, it is possible to communicate from a position directly above the tag main body 60 attached by the reader / writer R / W or from a position away from directly above.

Further, as shown in FIG. 20B, the RFID inlet 6 is attached to the end of the wire-like metal rod 9, and an interference wave of a high-frequency current i is generated on the surface of the wire-like metal rod 9 to radiate an electromagnetic wave. Communication can be performed from a place immediately above the RFID inlet 6 attached by the writer R / W or from a place away from directly above.
20A and 20B, it is preferable that the mounting position for improving the sensitivity is installed at a point of 1/4 wavelength from the end of the metal rod or a point of 1/2 wavelength period starting from this point. .

  If you want to communicate at a place away from the place where the RFID tag is attached, the RFID tag has a wire-like metal rod surface that is longer than the wavelength of the electromagnetic wave to be communicated, and the longitudinal direction of the RFID tag is parallel to the wire, and the slit surface inside the RFID tag is the wire It is installed so that it is almost upright, or connected to the end of the metal rod by direct or electromagnetic coupling so that the RFID tag is extended, and a high frequency current flows through the surface of the metal rod. Waves that are traveling waves, propagate through the metal surface, interfere with reflected waves that return at discontinuities in the propagation direction, and have waved abdomen with high and low wave heights. Electromagnetic waves are radiated from interference waves whose intervals are an integral multiple of half the wavelength and clear standing waves of the abdomen and nodes, enabling communication at a location directly above or away from directly above the attached RFID tag. It can provide an RFID tag and a communication method of an integrated shape with Shokubo.

  Furthermore, the metal rod of the above embodiment is inserted in a metal pipe in a non-contact manner through insulation, and is a type of wave that propagates in a coaxial cable or a coaxial pipe (a coaxial cable that is freely bent is also referred to as a coaxial pipe hereinafter). A mode wave is generated, and the metal rod is extended from the size of a 1/10 wavelength microdipole antenna to the size of a 1/4 wavelength monopole antenna at both ends or one end of the coaxial tube. A high frequency current is applied to the external surface. As a result, the high-frequency current becomes a traveling wave with the frequency of the communication frequency as a period, propagates through the metal surface, and undulates the wave that interferes with the reflected wave returning from the discontinuous part in the propagation direction. Interfering waves with a node and abdomen and abdomen or the interval between the node and the node being an integral multiple of half a wavelength and clear standing waves between the abdomen and the node are generated and propagated to the outer surface of the coaxial tube It is possible to provide a coaxial tube-shaped RFID tag integrated with a coaxial tube capable of communication by electromagnetic wave radiation from an interference wave or standing wave, and a communication method therefor.

Furthermore, as shown in FIG. 21 (FIGS. 21A and 21B), the tag main body 60 is installed on the inner conductor of the coaxial cable or the coaxial tube C, and the RFID tag can communicate with each other on the surface of the outer conductor.
In FIG. 21A, a tag main body 60 is installed on the inner conductor of a coaxial cable or coaxial tube C, and a high-frequency current i flowing through the coaxial inner conductor is coaxially connected by an antenna such as a monopole antenna or a minute dipole antenna 76 directly connected to the coaxial end. This shows that high-frequency current flows through the inner and outer conductor surfaces, and communication with the reader / writer R / W is possible everywhere on the outer conductor surfaces.
FIG. 21B shows that the antenna portions are provided at both ends of the coaxial cable or the coaxial tube C so that the high-frequency current i flowing through the internal and external conductors can be positively flowed.
Note that the electromagnetic field distribution inside the coaxial line is distributed in the coaxial mode (TEM) having no cutoff frequency, but is not particularly shown.

  Further, the antenna portion C1 of the coaxial cable or the coaxial tube C can have various shapes such as a columnar shape, a tapered shape, and a loop shape. The dimensions of the antenna section may range from a minute dipole antenna 76 having a length of about 1/10 wavelength to a monopole antenna length λ / 4 having a length of 1/4 wavelength. Good, one side is acceptable.

  Furthermore, in this example, the metal rod of the above embodiment is inserted into a metal pipe in a non-contact manner through insulation, and propagates in a coaxial cable or a coaxial pipe (a coaxial cable that is freely bent is also referred to as a coaxial pipe hereinafter). A coaxial mode wave, which is a type of wave, is generated, and a metal rod is extended from the size of a monopole antenna of 1/4 wavelength to the size of a minute dipole antenna at the opening at both ends or one end of the coaxial tube. A high frequency current can flow through the external surface. As a result, the high-frequency current becomes a traveling wave with the frequency of the communication frequency as a period, propagates through the metal surface, and undulates the wave that interferes with the reflected wave returning from the discontinuous part in the propagation direction. Interfering waves with a node and abdomen and abdomen or the interval between the node and the node being an integral multiple of half a wavelength and clear standing waves between the abdomen and the node are generated and propagated to the outer surface of the coaxial tube It is possible to provide a coaxial tube-shaped RFID tag integrated with a coaxial tube capable of communication by electromagnetic wave radiation from an interference wave or standing wave, and a communication method thereof.

The tag body 60 in the third to fifth embodiments is interchangeable because the tag body 60 in FIG. 1 and the tag body 60 in FIG. 14F have the same equivalent circuit described in FIG. 5B. Therefore, in addition to the illustrated example, various combinations of tag bodies having different shapes but electromagnetically equivalent are possible.
Furthermore, the tag main body 60 in the third to fifth embodiments is equivalent to the tag main body when the metal arm 70A extended substantially half-winding in FIG. 14E is eliminated, and the equivalent circuit described in FIG. 5B is the same and can be replaced. It is. Therefore, in addition to the illustrated example, all combinations of tag bodies that have different shapes but are electromagnetically equivalent are possible.

As a sixth embodiment of the present invention, as shown in FIG. 22 (FIGS. 22A and 22B), an RFID tag 70 is installed in a recessed portion of the metal surface 8 so as to communicate with the attached detection instrument D. Can also be used.
In the present embodiment, an attachment type detection device incorporating a dipole antenna externally attached to the antenna surface of a reader / writer, the dipole antenna is parallel to the antenna surface of the reader / writer and is approximately 0 to about 10 wavelengths of communication electromagnetic waves. In this case, it is preferable to use an instrument that is attached to a quarter wavelength position. As a result, the central portion of the dipole antenna of the instrument attached to the reader / writer is connected to the RFID tag of each of the above-described embodiments installed in a narrow place where the reader / writer cannot be brought close to each other. Since this is the maximum current range, this portion can be brought close to the target RFID tag to the electromagnetic induction range, and an externally attached detection instrument that enables one-to-one communication and its communication method can be provided.
FIG. 22A is a diagram for explaining a method of communicating with an RFID tag 70 that is installed in a deep place and is difficult to respond. The attach-type detection device D attached to the reader / writer R / W includes a dipole antenna rod D2 and an insulating support D1. Attach the detection device D to the reader / writer R / W antenna surface DA to D2 in parallel to the mounting position h separated by about 0 or 1/2 wavelength, and the closest to the tag main body 60 installed in the metal depression 81 The center part of the dipole antenna rod D2 is brought close to each other, and communication is performed using electromagnetic induction between a high-frequency current i induced in the center part of D2 and a high-frequency magnetic flux Φ penetrating the tag body 60 in common.

Further, according to the present embodiment, there is provided an attachment type detection instrument incorporating a dipole antenna externally attached to the antenna surface of the reader / writer. The instrument is attached to a position of about a quarter wavelength, preferably a quarter wavelength. As a result, the central portion of the dipole antenna of the device attached to the reader / writer is connected to the RFID tag of each of the embodiments described above in a narrow place where the reader / writer cannot be brought close to each other. Therefore, it is possible to provide an external non-contact attached detection instrument and its communication method that allows one-to-one communication by bringing this portion close to the electromagnetic induction range.
Further, FIG. 22B shows a method of reliably communicating one-to-one with the dense RFID tags 70 in which the high-sensitivity central portion of the dipole antenna rod D2 of the attached detection device D points to the target RFID tag 70. .

According to this communication method, small RFID tags whose outer dimensions are 3 mm wide, 4 mm long and 6 mm long on an aluminum plate that is wider than the wavelength of the communication electromagnetic wave, for example 200 mm long and 200 mm wide, are closely packed in parallel with a gap of about 1 mm. In this case, it has been confirmed that the central portion of the dipole antenna rod having a diameter of 2 mm and a length of 52 mm is close to the RFID tag and can be identified one-to-one.
The RFID tag uses an inlet (RKT102) manufactured by Hitachi, Ltd., and the reader uses R001M manufactured by Seconic.

As a seventh embodiment of the present invention, there is provided a detection instrument for detecting through an obstacle when the RFID tag of the present invention or a general RFID tag is installed through an obstacle that reflects and absorbs electromagnetic waves and the communication electromagnetic wave does not reach directly. The communication method will be described with reference to FIGS.
It is assumed that there are concrete, asphalt, earth and sand, water, seawater, metal objects, and the like as obstacles GND for electromagnetic waves to be communicated in this embodiment, and RFID tags are installed therethrough. In this embodiment, communication is performed using the extension detection device DTR. The extension detection instrument includes a detection unit DT that directly communicates with the RFID tag, a transmission unit that transmits this signal, a re-radiation unit TR that is close to the reader / writer side, and a transmission unit T that connects the detection unit DT. Yes. The detection unit has a role of directly communicating with the RFID tag, and is configured by one type of antenna such as a micro loop, a monopole, a dipole, or a ceramic antenna. The transmission unit has a role of delivering electromagnetic waves to be communicated to the other end, and is configured by one type of antenna such as a coaxial line, a balanced line, a strip line, a waveguide, or a dielectric rod. The re-radiating part has a role of electromagnetic coupling with a reader / writer attached to the re-radiating part, and can be configured by one type of antenna such as a micro loop, a monopole, a dipole, a ceramic, a patch antenna, or an electromagnetic horn. . The best combination differs depending on the communication electromagnetic wave, but if the communication electromagnetic wave is in the LF / HF band, the detection unit and the re-radiation unit are preferably micro loop antennas. In the case of UHF / microwave band, the detection unit is selected from antennas such as micro loops, monopoles, dipoles, ceramics, etc., and the re-radiation unit is preferably an antenna such as dipoles, ceramics, patch antennas, etc. A coaxial line is also suitable in the electromagnetic wave band.

The example of FIG. 23 is a configuration diagram of the best extension detection instrument DTR in the case of the LF / HF band. The detection unit DTL may be formed of a minute loop antenna, and resonance may be adjusted by a tuning capacitor TCC in order to further improve sensitivity. The re-radiating part TRL may be made close to a position formed by a minute loop antenna and capable of communicating with the reader / writer R / W, and resonance may be taken with a tuning capacitor TCC in order to further improve sensitivity. The transmission unit TCX is a coaxial line. Note that DTL and TRL can easily improve communication sensitivity when the diameters of adjacent micro loop antennas are approximately the same size and number of windings.
The example of FIG. 24 is an extension detection instrument DTR in the case of the UHF / microwave band, and the detection unit DTC is formed of a ceramic antenna. This is effective when the RFID tag 70 to be communicated is in a narrow place. The re-radiating part TRD is formed by a linear antenna represented by a dipole antenna, and is brought close to a position where it can communicate with the reader / writer R / W. The transmission part TCX connecting DTC and TRD is a coaxial line.
In the example of FIG. 25, the detection unit DTC in the example of FIG. 24 is a detection unit DTD having the same structure as the dipole antenna of the re-radiating unit TRD. The transmission part TCX connecting DTD and TRD is a coaxial line. This example is characterized in that sufficient communication sensitivity can be obtained when communicating with the RFID tag 70 embedded in the metal plane level.
The example of FIG. 26 includes a detection unit DTM in which the detection unit DTC in the example of FIG. 24 is a monopole antenna tener having a length of ¼ wavelength, and the transmission unit TCX connecting this DTM and TRD is used as a coaxial line. Yes. In this example, the RFID tag 70 attached to the inner wall surface or bottom of the metal tube can be communicated by inserting the detection unit DTM from the opening of the tube.
As described above, in the extension type RFID tag detection instrument of the present embodiment, when the communication electromagnetic wave is in the LF / HF band, the detection unit and the re-radiation unit are micro loop antennas, and the transmission unit is a coaxial line. In addition, when the communication electromagnetic wave is in the UHF / microwave band, any one antenna such as a micro loop, a monopole, a dipole, and a ceramic is selected for the detection unit, and the re-radiation unit is a dipole, a ceramic, a patch antenna, etc. Any one type of antenna is selected, and the transmission unit is integrally configured as a coaxial line.

As another application of the extension detection device shown in the examples of FIGS. 23 to 26, a normal RFID tag and a sufficiently small tag main body 60 according to the present invention are difficult to reach by hand or where a communication electromagnetic wave is difficult to reach. It can also be applied in some cases. For example, if it takes effort to approach the ceiling, wall surface, road surface, lower part of the manhole, or other dangerous areas, the work load can be reduced by using the extension detection device of this embodiment that attaches to the antenna unit of the existing reader / writer in a non-contact manner. Remote communication can be used to reduce the risk.
The inventors have confirmed that in the examples of FIGS. 23 to 26, the transmission unit T is a coaxial line (1.5D2V) and the length thereof is about 5 m, and the operation is sufficiently performed. The reader used at the time of confirmation is a multi-reader module STL920B manufactured by Taisei Lamic in the HF band, and a handy reader R001M manufactured by Seconic in the microwave.

1: Dipole antenna 20: Slit-shaped matching circuit 20L: “L” -shaped slit-shaped matching circuit 20S: On-chip matching circuit 20T: “T” -shaped slit-shaped matching circuit 30: IC chip 31: IC logic circuit 31A: Electrode 31B : Electrode 4: Matching circuit area (part where matching circuit area is cut out)
5: Base material 50: Upright holding portion 51: Seat or mounting surface 51A: Seat or mounting surface 51B: Seat or mounting surface 51C: Seat or mounting surface 6: RFID inlet 60: Tag body 611: Cut line 61S : Spacer 70: RFID tag 70A: Metal arm 70B: Stopper 70C: Dielectric or magnetic filler 70D: Adhesive 70M: Image RFID tag 70SD1: Shell structure protection metal fitting 70SD2: Folding structure protection metal fitting 70SD3: Folding terminal Structure protective metal fitting 70SD4: Terminal structure protective metal fitting 70SD5: C-shaped flat surface protective metal fitting 70SD6: H-shaped flat surface protective metal fitting 70SD7: Electromagnetic wave mode generating protective metal fitting 70SD8: Half-wave resonance / electromagnetic wave mode generating electric protective metal fitting 71: Micro loop antenna 71E: Small loop antenna equivalent Path 71S: Minute loop antenna pattern 72: Two-turn minute loop antenna 72C: Connection point region 72E of loop start point and end point 72E: Two-turn minute loop antenna equivalent circuit 75: Monopole antenna 76: Minute dipole antenna 77: Dipole antenna 78: Mounting hole 79: Clearance 8: Metal surface 81: Metal surface depression 9: Wire-shaped metal rod
R / WA: Reader / writer internal antenna
GND ： Obstacle of communication electromagnetic wave
DTR: Extension detection device
DT: Detector
DTL: Micro loop antenna of the detector
DTM: Monopole antenna for detector
DTD: Dipole antenna of the detector
DTS: Ceramic antenna of the detector
T: Transmission section
TCX: Coaxial line
TR: Re-radiation part
TRL: Micro loop antenna for re-radiating part
TCC: Tuning capacitor
TRD: Dipole antenna AG for re-radiating part: Mounting angle
I: Surge current, welding current, electrostatic discharge current
Q: Static electricity
i: High frequency current
iTM: TM fundamental mode current ID: Half-wave resonance current
Di: External dimensions
A1: Loop surface
AM: Image loop surface
AS: Vertical dimension of enlarged surface
A0: Vertical dimension of loop surface without protective bracket
W: Interference wave
WF: Traveling wave
WR: Reflected wave
WP: Abdomen
WV: Node
WL: Half-wave period Φ: High-frequency magnetic flux Φ1: High-frequency magnetic flux Φ2 without protective metal fittings: High-frequency magnetic flux λg with protective metal parts λg: Wavelength λg / 4 in the medium: Monopole antenna length λ / 4 in the medium: Monopole antenna length λ / 2: Dipole antenna length
R / W: Reader / Writer
C: Coaxial cable or coaxial pipe
C1: Coaxial cable or coaxial tube antenna
D: Attached detection instrument
D1: Support
D2: Dipole antenna rod
DA: Reader / writer antenna surface
h: Mounting position
BB: Folding line
a−a ′: Cross section
S−S ′: Cross section.

Claims (10)

An RFID tag body including an IC chip and a micro loop antenna electrically connected to the IC chip;
A metal arm that covers the IC chip via an insulating layer;
An attachment surface for attaching the RFID tag body to the metal member such that the loop surface of the minute loop antenna is substantially perpendicular to the attachment metal surface;
The micro loop antenna is formed as a loop of at least one turn including the IC chip in the electromagnetic wave radiation direction,
The metal arm and the minute loop antenna are connected to each other at a connection point region where a start point and an end point corresponding to one turn of the loop are connected, and are mechanically contacted and electrically connected, or , Having a connection structure of any of the connection structures that are mechanically separated and electrically connected by electromagnetic coupling,
The metal arm extends in one direction along the winding direction of the loop from the end point of the loop on the electromagnetic radiation direction side of the mounting surface across the IC chip and the minute loop antenna, The IC chip is covered by a length corresponding to a substantially half turn of the loop,
The RFID tag characterized in that the length of the metal arm is from the size of the IC chip to λ / 4, where λ is the wavelength of the communication frequency of the RFID tag body. An RFID tag body including an IC chip and a micro loop antenna electrically connected to the IC chip;
A metal arm that covers the IC chip via an insulating layer;
An attachment surface for attaching the RFID tag body to the metal member such that the loop surface of the minute loop antenna is substantially perpendicular to the attachment metal surface;
The micro loop antenna is formed as a loop of at least one turn including the IC chip in the electromagnetic wave radiation direction,
The metal arm and the micro loop antenna are integrally formed of the same metal material, and are mechanically contacted and electrically connected in a connection point region where a start point and an end point corresponding to one turn of the loop are connected. Has a connection structure that is also connected to
The metal arm extends in one direction along the winding direction of the loop from the end point of the loop on the electromagnetic radiation direction side of the mounting surface across the IC chip and the minute loop antenna, The IC chip is covered by a length corresponding to a substantially half turn of the loop,
The RFID tag, wherein the metal arm is formed by further extending the loop in the winding direction of the loop from the connection point region so as to cover the IC chip through the insulating layer . In claim 2,
Inside the loop of the micro loop antenna, a dielectric or magnetic filling layer is formed,
The RFID tag according to claim 1, wherein the mounting surface is constituted by an edge of the loop on a side opposite to the IC chip in the electromagnetic wave radiation direction of the loop with the filling layer interposed therebetween. In claim 1,
The metal arm is formed separately from the metal micro-loop antenna,
The loop of the micro loop antenna has a length corresponding to one turn,
The metal arm has a length corresponding to at least approximately half of the loop of the micro loop antenna;
The metal arm and the loop of the micro loop antenna are electromagnetically coupled in the connection point region,
The metal arm extends in the one direction along the winding direction of the loop from the connection point region, and is formed to cover the IC chip on the loop located in the electromagnetic wave radiation direction from the attachment surface side. An RFID tag characterized by having In claim 4,
A dielectric or magnetic filling layer is formed inside the loop of the micro loop antenna and between the metal arm and the loop,
The RFID tag according to claim 1, wherein the mounting surface is formed by extending the metal arm to a side opposite to the IC chip in the electromagnetic wave radiation direction of the loop with the filling layer interposed therebetween. An RFID tag body including a micro loop antenna and an IC chip electrically connected to the micro loop antenna;
Metal fittings for placing the RFID tag body inside,
An attachment surface for attaching the RFID tag body to the metal member such that the loop surface of the minute loop antenna is substantially perpendicular to the attachment metal surface;
The micro loop antenna is formed as a loop of at least one turn including the IC chip,
The metal fitting has a metal arm that extends in the winding direction of the loop and covers the IC chip so as to cover the IC chip on the loop in the electromagnetic wave radiation direction,
A dielectric or magnetic filling layer is formed inside the loop of the micro loop antenna and between the metal fitting and the loop,
The metal arm and the minute loop antenna are connected to each other at a connection point region where a start point and an end point corresponding to one turn of the loop are connected, and are mechanically contacted and electrically connected, or , Having a connection structure of any of the connection structures that are mechanically separated and electrically connected by electromagnetic coupling,
The metal arm extends in one direction along the winding direction of the loop from the end point of the loop on the electromagnetic radiation direction side of the mounting surface across the IC chip and the minute loop antenna, The IC chip is covered by a length corresponding to a substantially half turn of the loop,
The RFID tag according to claim 1, wherein the length of the metal arm is λ / 4 that actively promotes resonance when the wavelength of the communication frequency of the RFID tag body is λ. In claim 6,
The metal arm is formed separately from the micro loop antenna,
The loop of the micro loop antenna has a length corresponding to one turn,
The metal arm has a length corresponding to at least approximately half of the loop of the minute loop antenna,
The metal arm and the loop are electromagnetically and mechanically connected in the connection point region of the loop,
The RFID tag according to claim 1, wherein the metal arm is formed so as to cover the IC chip on the loop that is in an electromagnetic wave radiation direction from the mounting surface side . In claim 1 or 2,
The RFID tag main body includes a planar micro loop antenna that also serves as a matching circuit formed on a base material, and the IC chip that is electrically connected to the micro loop antenna.
An RFID tag comprising an upright holding portion for holding the RFID tag main body with the loop surface of the minute loop antenna substantially upright on a metal mounting surface. In claim 8,
The RFID tag is
A region of the matching circuit can be cut out from a central portion of the dipole antenna in an RFID inlet having an IC chip connected through a slit-like matching circuit formed on a planar dipole antenna of a metal plate or metal foil. The planar micro loop antenna also used as the matching circuit is an RFID tag body,
The RFID tag, wherein the side of the minute loop antenna to which the IC chip is not connected is bent at a substantially right angle to form the upright holding portion. In claim 1 or 2,
The RFID tag main body in which the micro-loop antenna also serving as a matching circuit is integrally formed of the same semiconductor as the RFID logic circuit on the IC chip, and the loop surface of the IC chip substantially perpendicular to the metal mounting surface An upright holding part with the side surface of the RFID tag main body as a seat part,
The RFID tag , wherein the minute loop antenna also used as the matching circuit is integrated on the IC chip, and the upright holding portion is formed by a side surface of a base material of the IC chip .

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