JP2002319009A - Rfid tag structure and electromagnetic coupler of rfid tag - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an RFID tag structure and an electromagnetic coupler of an RFID tag capable of increasing the range of applications of the RFID tag by extending the communicable distance of the RFID tag. SOLUTION: An induction coil 6 is embedded in the electromagnetic coupler 5, with the connecting ends 6a and 6b of the coil connected to a receptacle 5b. A connecting terminal 7c connected to the connecting ends 7a and 7b of a loop antenna 7 is connected to the receptacle 5b by a plug 5c. The electromagnetic coupler 5 is provided with a mounting part 5a by which the RFID tag 1a is mounted in a position where the induction coil 6 is electromagnetically coupled to the antenna coil 2a.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an RFID tag structure for performing communication by electromagnetic waves using an antenna coil, and an RF tag.
The present invention relates to an electromagnetic coupler of an ID tag.

[0002]

2. Description of the Related Art Conventionally, RFID tags (Radio Frequency
IDentification TAGs include an electromagnetic induction type and an electromagnetic coupling type, and both of them are designed to communicate with a reader / writer or the like in a non-contact manner using electromagnetic waves.

An RFID tag has an antenna coil and a control unit. When the antenna coil receives a transmission signal from a reader / writer, the control unit stores the signal as power in a capacitor and stores the signal using the power. The information such as the ID code stored in the unit is transmitted from the antenna coil to the reader / writer again.

As a transmission and reception system, ASK (Amplitude)
Shift Keying) and FSK (Frequency Shift Keyi)
ng) system, the former performs transmission and reception by intensity modulation of electromagnetic waves, and the latter performs transmission and reception by frequency modulation of electromagnetic waves.

When a general RFID tag is divided into antenna coils, a concentric disk-shaped antenna coil using a circular air-core coil and a cylindrical antenna coil in which an insulated copper wire such as an enamel wire is wound around a rod-shaped ferrite core. There are two types of antenna coils, the outer shape of which corresponds to the shape of each antenna coil, the former is formed in a disk shape, and the latter is formed in a rod shape.

An RFID tag having a concentric disk-shaped antenna coil performs communication by utilizing a change in magnetic flux in the surface direction of a circular coil, and an RFID tag having a cylindrical antenna coil.
The FID tag performs communication using a change in magnetic flux in the axial direction.

[0007]

However, generally, the communicable distance of an RFID tag is about several mm to several cm,
For example, when information stored in an RFID tag is read by a small reader / writer, the reader / writer needs to be close to the communicable distance of the RFID tag, that is, several mm to several cm, and several m to several cm. It is impossible to read from a position as far as 10 m. Therefore, the field of use of the RFID tag has been limited.

[0008] The present invention is to solve the above problems,
An object of the present invention is to provide an RFID tag structure and an RFID tag electromagnetic coupler capable of extending the communication range of the RFID tag and expanding the field of use of the RFID tag.

[0009]

According to a first aspect of the present invention, there is provided an RFID tag having an RFID tag having an antenna coil, a loop antenna, and electromagnetic coupling between the antenna coil and the loop antenna. An electromagnetic coupler, an induction coil is provided in the electromagnetic coupler main body, and a mounting portion for electromagnetically coupling the antenna coil of the RFID tag by disposing the antenna coil close to the induction coil is provided. A connection end and a connection end of the loop antenna are connected in series.

The present invention is constructed as described above, so that the RF
A loop antenna is electromagnetically coupled to the ID tag via an electromagnetic coupler, and the communicable distance of the RFID tag can be arbitrarily expanded by the action of the loop antenna.

That is, the connection end of the induction coil provided on the main body of the electromagnetic coupler and the connection end of the loop antenna are connected in series, the RFID tag is mounted on the mounting portion, and the antenna coil of the RFID tag is used for induction. The antenna coil of the RFID tag and the loop antenna are electromagnetically coupled to each other via the induction coil by electromagnetically coupling the coil close to the coil, and the communicable distance of the RFID tag can be arbitrarily expanded by the action of the loop antenna. You can do it.

First, RFI is sent from an external reader / writer or the like.
When reading the unique information stored in the D tag, the information is transmitted from the antenna coil of the RFID tag as a change in magnetic flux to the induction coil.

Then, a current corresponding to the change in the magnetic flux flows through the induction coil, and the current also simultaneously flows through the loop antenna forming a series circuit therewith, and the magnetic flux changes over the entire circumference of the loop antenna. . Therefore, information can be read by a reader / writer or the like from all directions outside the loop antenna.

Conversely, power and information are transmitted from a reader / writer
When transmitting to an FID tag, a change in magnetic flux caused by a signal transmitted from an antenna of a reader / writer or the like is first captured by a loop antenna, whereby a current flows through the loop antenna, and the induction coil amplifies the current in the form of a magnetic flux. (Amplification by the number of windings) and the change in the amplified magnetic flux
The antenna coil of the ID tag catches it.

As described above, since communication is possible from all directions of the loop antenna, the RFI can be formed with a simple structure at low cost.
The communicable distance of the D tag can be arbitrarily extended or enlarged depending on the size and shape of the loop antenna.

An RFID which is commercially available as a standard
Tags can be used as they are. Also, by simply attaching the RFID tag to the mounting portion of the electromagnetic coupler, the antenna coil and the loop antenna can be stably electromagnetically coupled to each other, so that the construction is simplified and the operation can be stably performed for a long time. .

Further, by setting the RFID tag to the mounting portion of the electromagnetic coupler in advance, management, storage, transportation, and construction can be more easily performed.

Further, a loop antenna can be connected to the electromagnetic coupler in advance, and the electromagnetic coupler, the RFID tag, and the loop antenna can be unitized.
Transportation and construction can be further simplified.

When the antenna coil of the RFID tag is formed in a cylindrical shape or concentric disk shape, a commercially available RFID tag can be used, so that it is easy to obtain and the cost can be reduced by mass production.

Further, when the loop antenna is fixed to a sheet-like base material, the loop antenna fixed to the sheet-like base material can be easily formed into a specific shape. Easy to do.

Further, the electromagnetic coupler of the RFID tag according to the present invention is an electromagnetic coupler for electromagnetically coupling the antenna coil of the RFID tag and the loop antenna. A mounting portion that electromagnetically couples the antenna coil of the RFID tag by disposing the antenna coil close to the induction coil, so that a connection end of the loop antenna can be connected to a connection end of the induction coil. And

The above-described RFID tag structure can be easily configured using the electromagnetic coupler of the RFID tag.

[0023]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an embodiment of an RFID tag structure and an electromagnetic coupler of an RFID tag according to the present invention. FIG. 1 is a cross-sectional explanatory view showing an RFID tag structure according to the present invention applied to an RFID tag having a concentric disk-shaped antenna coil. FIG. 2 is a configuration of an electromagnetic coupler applied to an RFID tag having a concentric disk-shaped antenna coil. FIG.

FIG. 3A is a plan view showing the configuration of an RFID tag having a concentric disk-shaped antenna coil, and FIG.
Is a schematic diagram showing a state of a magnetic field generated in an RFID tag having a concentric disk-shaped antenna coil, and FIG. 4 is a block diagram showing a configuration of a control system of the RFID tag.

FIGS. 5A and 5B are a cross-sectional view and a plan view showing an RFID tag structure according to the present invention applied to an RFID tag having a cylindrical antenna coil, and FIG. 6 is a cylindrical antenna coil. FIG. 7 is a perspective explanatory view showing a configuration of an electromagnetic coupler applied to an RFID tag having an RFID tag. FIG. 7 is a schematic diagram showing a configuration of an RFID tag having a cylindrical antenna coil and a state of a magnetic field generated therein.

FIG. 8A shows an RFID tag structure in which a loop antenna is fixed to a sheet-like base material and an RFID tag is attached to an electromagnetic coupler attached to the sheet-like base material. It is a side view which shows the state before use by which the material was wound.

FIGS. 8 (b) and 8 (c) show the state of FIG.
FIG. 9A is a side view and a plan view showing a state where the sheet-like base material is extended. FIG. 9 shows a configuration in which a plurality of RFID tag structures shown in FIG. It is a plane schematic diagram which shows an example.

First, referring to FIGS. 1 to 4, an RF tag having a concentric disk-shaped antenna coil 2a is shown as an example of an RFID tag structure and an electromagnetic coupler of the RFID tag according to the present invention.
The configuration when the ID tag 1a is adopted will be described.

The RFID tags 1a and 1b preferably employed in this embodiment are of the electromagnetic coupling type or the electromagnetic induction type.
D-tag, and in this embodiment, an electromagnetic induction type RFI
An embodiment using a D tag will be described below.

In FIG. 1, an electromagnetic coupler 5 includes a resin main body having electrical insulation, an induction coil 6 composed of a circular air-core coil embedded in the main body, and a concentric disk-shaped antenna coil 2a. The antenna coil 2a and the induction coil 6 are mounted close to each other and have a mounting portion 5a for electromagnetically coupling the RFID coil 1a.

The mounting portion 5a is formed of a shallow groove having a circular cross section so as to conform to the outer shape of the RFID tag 1a.
An induction coil 6 is arranged below the position a. The induction coil 6 is molded with resin and is incorporated in the electromagnetic coupler 5. The RFID tag 1a is bonded and fixed to the mounting portion 5a with an adhesive 11 or the like, and is stably mounted.

The connection ends 6a and 6b of the induction coil 6 embedded in the electromagnetic coupler 5 are connected to the conductive screw-type receptacle 5 exposed on the surface side of the electromagnetic coupler 5.
b, so that a screw-type plug 5c having conductivity can be screwed into the receptacle 5b.

Reference numeral 7 denotes a loop antenna, and connection terminals 7c are electrically connected to connection ends 7a and 7b of the loop antenna 7. Then, the plug 5c is screwed and fastened to the receptacle 5b with the connection terminal 7c interposed therebetween, whereby the induction coil 6 and the loop antenna 7 are connected as a series circuit via the connection terminal 7c, the plug 5c and the receptacle 5b. You.

Thus, the loop antenna 7 and the antenna coil 2a of the RFID tag 1a can be electromagnetically coupled via the induction coil 6 of the electromagnetic coupler 5.

The loop antenna 7 can be laid in any desired closed area and shape depending on the intended communication area. If the length (loop) of the loop antenna 7 is increased, the communication area is expanded accordingly, but the communication sensitivity tends to decrease in inverse proportion to the area. On the other hand, if the communication sensitivity of the RFID tags 1a and 1b and the reader / writer is high, the communication area can be expanded accordingly.

For example, in the case of an RFID tag 1a having a concentric disk-shaped antenna coil 2a having an outer diameter of 50 mm, according to an experiment, when the loop antenna 7 has an elongated loop shape, the maximum communication distance is about 10 to 20 m. It turns out that it can be expanded to.

In this embodiment, the connection ends 6a and 6b of the induction coil 6 and the connection ends 7a and 7
The electrical connection with the connector b is made detachable by screwing the conductive screw-type plug 5c and the receptacle 5b with the connection terminal 7c interposed therebetween, but the electrical connection may be made by soldering. .

The RFID tag structure shown in FIG.
This is an example in which communication is performed by electromagnetic waves using the concentric disk-shaped antenna coil 2a of the tag 1a, and as shown in FIG. 3A, a concentric disk-shaped antenna coil 2a and a semiconductor serving as a control unit The IC chip 4 is directly connected without a printed circuit board or the like.
The size of the tag 1a is reduced.

The semiconductor IC chip 4 is formed by integrally packaging an IC (semiconductor integrated circuit) chip, an LSI (semiconductor large-scale integrated circuit) chip, or the like. As shown in FIG. 4, a CPU 4a serving as a control unit, a memory 4b serving as a storage unit, a transceiver 4c, and a capacitor 4d serving as power storage means are provided.

A signal transmitted from an external reader / writer (not shown) is transmitted to the CPU 4a via the transceiver 4c, and the electric power is stored in the capacitor 4d. Note that there may be no capacitor 4d serving as a power storage means, and power may be continuously supplied to the semiconductor IC chip 4 from an external reader / writer or the like.

The CPU 4a is a central processing unit that reads out programs and various data stored in the memory 4b, performs necessary calculations and judgments, and performs various controls.

The memory 4b stores various programs for operating the CPU 4a and various kinds of unique information when the electromagnetic induction tag 1a is installed for various purposes.

As an example of the concentric disk-shaped antenna coil 2a shown in FIG. 3, a copper wire having a diameter of about 30 μm is wound concentrically in the form of a single wire wound in a radial direction with multiple layers. The inductance of the coil 2a is 9.
5 mH (frequency 125 kHz), the antenna coil 2
The capacitance of a capacitor separately connected to a for resonance is 1
It was about 70 pF (frequency 125 kHz). FIG. 3 (b)
Shows a magnetic field H generated in the RFID tag 1a.

The RFID tag 1a of the present embodiment has a single radio frequency amplitude shift keying (ASK).
ying) wireless communication system, with a wide resonance frequency band,
CM with very low power consumption incorporating a special transmitting / receiving circuit with an air-core antenna coil 2a having a wire diameter of several tens of microns
An RFID tag 1a using an OS-IC was employed.

The RFID tag receives an AC magnetic field transmitted from an external reader / writer or the like at a resonance frequency of an antenna coil built in the RFID tag. At this time, the conventional RFID tag uses two waves of 125 kHz and 117 kHz, for example, in a frequency shift keying (FSK) system in order to extend the communication distance, and increases the reception power. It has been common to use a ferrite core for the antenna coil, increase the wire diameter of the coil, and extend the coil to extend the communication distance.

Frequency shift keying (FS) using two radio frequencies
In the K) method, when a conductive member such as a metal or a magnetic material approaches, the reception frequency shifts, the reception power decreases, a communication error occurs, communication becomes impossible, and the communication distance is extremely reduced. The stereotype that the RFID tag cannot be used by being attached to a conductive member such as a metal or a magnetic material is dominant because it becomes impossible.

However, recently, a radio frequency uses a radio communication system of one-amplitude amplitude shift keying (ASK), and a special transmitting / receiving circuit is formed by an air-core antenna coil having a wide resonance frequency band and a wire diameter of several tens of microns. An RFID tag that can be used by being attached to a conductive member such as a metal or a magnetic material using a built-in CMOS-IC with very low power consumption has been proposed and widely marketed.

Next, referring to FIGS. 5 to 7, an RF tag having a cylindrical antenna coil 2b will be described as an example of the RFID tag structure and the electromagnetic coupler of the RFID tag according to the present invention.
The configuration when the ID tag 1b is adopted will be described.

FIG. 5 shows an RFID tag structure using a rod-shaped RFID tag 1b having a cylindrical antenna coil 2b. In FIG. 5, the induction coil 6 built in the electromagnetic coupler 5 is formed in an air-core cylinder shape.
The mounting portion 5a of the rod-shaped RFID tag 1b is an induction coil 6.
Is formed by an elongated insertion hole having a circular cross section formed inside. The induction coil 6 is molded with resin and is incorporated in the electromagnetic coupler 5.

The rod-shaped RFID tag 1b is inserted into the mounting portion 5a having a long and narrow insertion hole having a circular cross section, and is stably mounted by being adhered and fixed with an adhesive or the like.

The connection ends 6 a and 6 b of the induction coil 6 embedded in the electromagnetic coupler 5 are connected to the conductive screw-type receptacle 5 exposed on the surface side of the electromagnetic coupler 5.
b, so that a screw-type plug 5c having conductivity can be screwed into the receptacle 5b.

On the other hand, the connection ends 7a, 7 of the loop antenna 7
The connection terminal 7c is electrically connected to b. Then, the plug 5c is screwed and fastened to the receptacle 5b with the connection terminal 7c interposed therebetween, whereby the connection terminal 7c, the plug 5
The induction coil 6 and the loop antenna 7 are connected as a series circuit via the connector c and the receptacle 5b.

Thus, the loop antenna 7 and the antenna coil 2b of the RFID tag 1b can be electromagnetically coupled via the induction coil 6 of the electromagnetic coupler 5.

As shown in FIG. 7, the antenna coil 2b formed in a cylindrical shape by single wire winding has an axial direction (FIG. 7).
(In the left-right direction), a cylindrical core member 3 such as an iron core or ferrite is inserted. Numeral 8 denotes a glass container which becomes the exterior of the RFID tag 1b.

For example, as an example of the antenna coil 2b, a copper wire having a diameter of about 30 μm is wound in a single wire and is wound in a multilayer shape in the radial direction and in a cylindrical shape in the axial direction. In this state, the inductance was about 9.5 mH (frequency 125 kHz), and the capacitance of a capacitor separately connected to the antenna coil 2a for resonance was about 170 pF (frequency 125 kHz).
Other configurations are the same as those of the above-described embodiment, and the same effects can be obtained.

FIG. 8 shows another embodiment of the RFID tag structure according to the present invention. In the present embodiment, the loop antenna 7
Is fixed to a sheet-like substrate 9, and the sheet-like substrate 9 is further fixed.
The electromagnetic coupler 5 is fixed by bonding or the like, and the connection ends 7a and 7b of the loop antenna 7 are electrically connected to the connection ends 6a and 6b of the induction coil 6 by the plug 5c of the electromagnetic coupler 5 to provide an electromagnetic coupler. The RFID tag 1 is attached to the mounting portion 5a of the
a and 1b are fixed.

As the loop antenna 7, for example, one obtained by laminating and fixing a 0.3 mm copper stranded wire to a base material 9 made of a soft plastic sheet such as vinyl chloride resin, polyethylene, or polypropylene can be used.

In this embodiment, as shown in FIG. 8, an example in which the sheet-like base material 9 is formed in an elongated shape will be described, but the sheet-like base material 9 having various shapes such as a square or a circle is looped. The antenna 7 may be fixed in a desired loop shape. Further, a protective film may be further formed on the surface side of the loop antenna 7.

The present embodiment is an example in which fixing screw holes 9a are formed at four corners of the sheet-like base material 9, but an adhesive layer and a release layer are provided on the back side of the sheet-like base material 9. When the sheet-like base material 9 to which the loop antenna 7 is fixed is formed at a target place, the release layer may be removed to expose the adhesive layer, and the adhesive may be fixed by bonding.

FIG. 9 shows an example in which a plurality of RFID tag structures shown in FIG. 8 are arranged in series to form a guide rail for traveling of an unmanned vehicle, a traveling robot 10 or the like. Unmanned vehicles and traveling robots
The reader 10 is equipped with a reader 12 for reading the information of the RFID tags 1a and 1b and a microcomputer (microcomputer). The position information stored in each of the RFID tags 1a and 1b is read and a pre-programmed condition is read. , Or the vehicle can be controlled to perform an automatic operation of stopping at a predetermined position.

As another application example, a theft prevention system can be considered. For example, the loop antenna 7 is stretched around the room, and the RFID tags 1a, 1b
The reader device 12 that reads the information of the RFID tag 1 is attached when the product is taken out of the room.
It is also possible to configure so that the communication with a and 1b is cut off and an alarm is issued.

[0062]

Since the present invention has the above-described configuration and operation, it is possible to arbitrarily extend and expand the communicable distance of the RFID tag with a simple structure at low cost by the size and shape of the loop antenna. And the field of use of the RFID tag can be expanded.

That is, a loop antenna capable of communication from all directions is electromagnetically coupled to the RFID tag via an electromagnetic coupler, and the communicable distance of the RFID tag can be arbitrarily expanded by the action of the loop antenna. .

Further, an RFID which is commercially available as a standard
The tag can be used as it is, and the antenna coil and loop antenna can be stably and electromagnetically coupled simply by mounting the RFID tag on the mounting part of the electromagnetic coupler, which simplifies the construction and reduces the length. It can be operated stably over time.

Further, by setting the RFID tag to the mounting portion of the electromagnetic coupler in advance, management, storage, transportation, and construction can be more easily performed.

Further, a loop antenna can be connected to the electromagnetic coupler in advance, and the electromagnetic coupler, the RFID tag, and the loop antenna can be unitized.
Transportation and construction can be further simplified.

When the antenna coil is formed in a cylindrical shape or concentric disk shape, a commercially available RFID
Since tags can be used, they can be easily obtained, and cost can be reduced by mass production.

When the loop antenna is fixed to a sheet-like base material, the loop antenna fixed to the sheet-like base material can be easily formed into a specific shape, so that installation or laying is easy. Can be

Further, the above-described RFID tag structure can be easily configured using the electromagnetic coupler of the RFID tag according to the present invention.

[Brief description of the drawings]

FIG. 1 is an RFID having a concentric disk-shaped antenna coil
FIG. 3 is an explanatory sectional view showing an RFID tag structure according to the present invention applied to a tag.

FIG. 2 is an RFID having a concentric disk-shaped antenna coil.
It is a perspective view showing the composition of the electromagnetic coupler applied to the tag.

3A is a plan view showing a configuration of an RFID tag having a concentric disk-shaped antenna coil, and FIG. 3B is a schematic diagram showing a state of a magnetic field generated in the RFID tag having a concentric disk-shaped antenna coil. is there.

FIG. 4 is a block diagram illustrating a configuration of a control system of the RFID tag.

FIGS. 5A and 5B are RFIDs according to the present invention applied to an RFID tag having a cylindrical antenna coil;
It is sectional explanatory drawing and plane explanatory drawing which show a tag structure.

FIG. 6 shows an RFID having a cylindrical antenna coil.
It is a perspective explanatory view showing the composition of the electromagnetic coupler applied to the tag.

FIG. 7 shows an RFID having a cylindrical antenna coil.
FIG. 3 is a schematic diagram illustrating a configuration of a tag and a state of a magnetic field generated therein.

FIG. 8 (a) shows a sheet-like substrate in an RFID tag structure in which a loop antenna is fixed to a sheet-like substrate, and an RFID tag is attached to an electromagnetic coupler attached to the sheet-like substrate. 8A and 8B are a side view and a plan view showing a state in which the sheet-like base material of FIG. 8A is stretched at the time of use.

9 is a schematic plan view illustrating an example in which a plurality of RFID tag structures illustrated in FIG. 8 are arranged in series to form a guide rail for an unmanned vehicle, a traveling robot, or the like.

[Explanation of symbols]

 1a, 1b RFID tag 2a, 2b Antenna coil 3 Core member 4 Semiconductor IC chip 4a CPU 4b Memory 4c Transceiver 4d Capacitor 5 Electromagnetic coupler 5a Mounting part 5b Receptacle 5c Plug 6 ... Induction coils 6a, 6b ... Connection end 7 ... Loop antenna 7a, 7b ... Connection end 7c ... Connection terminal 8 ... Glass container 9 ... Sheet-shaped base material 9a ... Screw hole 10 ... Unmanned vehicle or traveling robot 11 ... Adhesive material 12 ... Reader machine

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2C005 HA02 HB10 JA03 LA25 LB34 5B035 BA03 BB09 CA01 CA23 5B058 CA17 KA24 5K012 AA03 AB03 AC06 AC08 AC10 AC02

Claims (4)

[Claims] An RFID tag having an antenna coil, a loop antenna, and an electromagnetic coupler for electromagnetically coupling the antenna coil and the loop antenna, wherein an induction coil is provided on the electromagnetic coupler main body, A mounting portion for providing an antenna coil of the RFID tag close to the induction coil and electromagnetically coupling is provided, and a connection end of the induction coil and a connection end of the loop antenna are connected in series. RFID tag structure. 2. The RFID tag structure according to claim 1, wherein the antenna coil is formed in a cylindrical shape or a concentric disk shape. 3. The RFID tag structure according to claim 1, wherein the loop antenna is fixed to a sheet-like base material. 4. An electromagnetic coupler for electromagnetically coupling an antenna coil of an RFID tag and a loop antenna, wherein an induction coil is provided in the electromagnetic coupler main body, and an antenna coil of the RFID tag is provided in the induction coil. And a mounting part for electromagnetic coupling by closely disposing the antenna and a connection end of the loop antenna so that a connection end of the loop antenna can be connected to a connection end of the induction coil.