KR100912585B1 - Tag device, antenna and portable card - Google Patents

Abstract

In the vicinity of the human body, high-quality wireless communication is performed without deterioration of radio wave radiation and reception characteristics and without interfering with communication of other IC tags. The main loop portion 11 is an elongated loop-shaped metal foil having an area smaller than that of the dielectric substrate 30, covering the surface and side surfaces of the dielectric substrate 30 so as to sandwich the dielectric substrate 30 therebetween. It is mounted in the horizontal direction on the surface of the dielectric substrate 30 to transmit and receive radio waves. The capacitive load portion 12 is provided at both ends of the main loop portion 11 covering the front surface of the dielectric substrate 30 and at both ends of the main loop portion 11 covering the surface of the back side of the dielectric substrate 30, respectively. It is a metal foil formed and has a load of a capacitance component. The control unit 20 is connected to the main loop unit 11 and controls information through radio waves.

Human body, RFID, radiation and reception characteristics, main loop, metal foil, transmission and reception

Description

Tag Devices, Antennas, and Portable Cards {TAG DEVICE, ANTENNA AND PORTABLE CARD}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tag device, an antenna, and a portable card, and more particularly, to a tag device for wireless communication, an antenna for radiating and capturing radio waves, and a portable card for wireless communication.

Recently, an automatic recognition technique called RFID (Radio Frequency-Identification) has attracted attention. RFID is a kind of wireless communication system that attaches an IC tag to an object and automatically identifies the object in a non-contact manner by radio. Since RFID can be connected to a network by attaching IC tags to all objects, development is rapidly progressing as an effective technology for the construction of the next generation ubiquitous network society.

The RFID system is composed of a reader / writer and an IC tag, and writes information to the IC tag or reads information stored in the IC tag from the reader / writer through each antenna by wireless communication. I do it.

In addition, the frequency bands used in RFID so far are 13.56 MHz bands and 2.45 GHz bands. However, in recent years, attention has been paid to IC tags using UHF (Ultra-High-Frequency: 300 MHz to 3000 MHz) bands.

The UHF band IC tag uses 952 MHz to 954 MHz band for communication, and it can take a longer communication distance with the reader / writer than the existing 13.56 MHz band or 2.45 GHz IC tag, thus increasing the communication range. It is possible.

On the other hand, since the IC tag does not have a power supply (battery), when the reader / writer communicates with the IC tag, the IC tag communicates by supplying power to the IC tag from radio waves or magnetic fields generated by the reader / writer.

That is, in RFID, a power source is genetically divided into a radio wave method and an electromagnetic induction method. For IC tags of 2.45 GHz band and UHF band, this is a radio wave system that converts the radio waves generated by the reader / writer into electric power, and for 13.56 MHz IC tags, electromagnetic induction that obtains power from magnetic fields generated near the antenna of the reader / writer. That's the way.

12 is a diagram illustrating the concept of a propagation method. In the 2.45 GHz band or the UHF band, the RFID system 100 that communicates is composed of a reader / writer 110 and an IC tag 120. The IC tag 120 includes an antenna 121, a rectifier circuit 122, and a control circuit 123.

When the IC tag 120 receives the radio wave transmitted from the reader / writer 110 via the antenna 121, the rectifier circuit 122 rectifies the radio wave that is an AC signal as a DC signal. The DC signal is used as a power source, and is applied to a control circuit 123 that performs modulation and demodulation control, logic control, and the like.

It is a figure which shows the concept of the electromagnetic induction system. In the RFID system 200 that communicates in the 13.56 MHz band, the antenna of the reader / writer and the antenna of the IC tag are composed of loop antennas 210 and 220, respectively. Antenna having a looped shape.

It is assumed that the loop antennas 210 and 220 are in close proximity, and when the current ia flows in the counterclockwise direction with respect to the loop antenna 210 on the reader / writer side, the magnetic field HI is generated upward as shown in the figure. . Then, in the loop antenna 220 on the IC tag side, the current ib flows (clockwise) in the direction to cancel this magnetic field HI, and the magnetic field H2 is generated downward.

As described above, in the 13.56 MHz band IC tag, power can be obtained using the loop antenna based on the current generated by the magnetic field generated by the electromagnetic induction (in the 13.56 MHz band, the electromagnetic induction is performed using the loop antenna. By doing so, the loop antenna itself is used not only as an antenna used for electromagnetic induction but also as an antenna for radiating normal radio waves.

Here, in the radio wave system described with reference to FIG. 12, the lower the frequency of the radio wave (the longer the wavelength), the longer distance communication becomes possible. Accordingly, it can be seen that the UHF band can obtain a communication distance of about three times or more even with a simple idea compared to the 2.45 GHz band.

On the other hand, in the electromagnetic induction method described in FIG. 13, the loop antennas of the reader / writer and the IC tag need to be in close proximity. When the 13.56 MHz band IC tag moves away from the reader / writer, the magnetic field weakens at once. As a result, power cannot be secured.

As specific communication distances, the maximum distance of 13.56 MHz is 70 m to 80 cm and the maximum of 2.45 m 2 is about 2 m. However, the UHF band is about 7 m as an experimental value (about 10 m in theory).

In addition, a dipole antenna (eg, a folded dipole antenna) having a length (λ / 2) of 1/2 of the wavelength lambda of the radio wave is basically used as the antenna used for the IC tag of the 2.45 GHz band and the UHF band.

Here, if the length of the antenna in each frequency band is found, λ (wavelength) = C (beam) / f (frequency), the antenna length of the 2.45 GHz band IC tag is 3 x 10 ⁸ /2.45 x 10 ⁹ ≒ 0.122m It is about 6 cm, which is half of.

Similarly ask the antenna length of the IC tag of UHF band (referred to as ^{953㎒), 3 × 10 8/} 953 × 10 6 amounts to approximately half the 15㎝ ≒ 0.3m (therefore, without changing the electrical length, simply In order to obtain the calculated communication distance based on the length of the antenna, an IC tag having a size of at least 6 cm is inserted in the 2.45 GHz band and an IC tag having a size of at least 15 cm in the UHF band. do).

In the 13.56 MHz band IC tag, for example, when a power source is used to obtain power by using a dipole antenna, the length of the antenna becomes 11 m, which is half of 3 × 10 ⁸ /13.56×10 ⁶ ≒ 22m. It is not a thing. For this reason, in the 13.56 MHz band, electric power is obtained by the electromagnetic induction system without using the radio wave system.

Thus, there is a drawback that the communication distance cannot be extended in the 13.56 MHz band IC tag. On the other hand, in the 2.45 GHz band, the communication distance is 2 m, so that the practical range is somewhat widened. However, in the 2.45 GHz IC tag, when a liquid such as water or alcohol is nearby, 2.45 GHz radio waves are blocked and absorbed. (2.45 Hz is the same frequency as the microwave).

On the other hand, since the UHF band has a long communication distance and there are no drawbacks of the 2.45 GHz band, it is easier to collectively read a plurality of IC tags from the reader / writer than the existing frequency band. In addition, since the UHF band has a large return of radio waves, the IC tag can be read even in a place not visible from the reader / writer.

As described above, IC tags using the UHF band have many advantages, and the expectation on the UHF band IC tag is high. However, in the present situation, the efficiency is high in an environment in which not only the UHF band but also the existing IC tag of 13.56 MHz band or 2.45 GHz band is included. The realization of a good RFID service is required.

As a conventional IC tag, the IC tag coated with the thin flexible protective laminate is provided (for example, patent document 1).

Patent Document 1: Japanese Patent Application Laid-Open No. 08-88586 (paragraphs [0018] to [0021], FIG. 3)

<Start of invention>

Problems to be Solved by the Invention

As an application field of RFID, an IC tag card is embedded in a card that can be carried by a person, and the IC tag card is used to manage entry and exit of users on railroads and airlines, or to shop at department stores using the card. It is contemplated that the services used are widely performed.

Here, as a kind of antenna used in a conventional UHF-to-IC tag, there have been many configurations using a folded dipole antenna.

14 is a diagram illustrating a folded dipole antenna. A dipole antenna dp is an antenna that transmits radio waves by receiving a high frequency from a feeder (wave source) located at the center of one conductor, and is the most basic form of a linear antenna (antenna length is basically λ / 2). ). The folded dipole antenna fdp is an antenna having a structure in which a conductor of one wavelength is folded based on the dipole antenna dp.

In general, an IC tag having a folded dipole antenna fdp in which a card is in contact with a human body, such as being carried in a pocket of a person's chest or being held close to a reader / writer with a card in hand. In the UHF band card in which the chip is embedded, there is a problem that when the human body is in the vicinity of the human body, the radiation of the radio wave is blocked and absorbed by the human body, thereby deteriorating the radiation / reception characteristics of the radio wave.

Fig. 15 is a diagram showing a problem of the conventional UHF card. The dipole antenna dp is shown in the vicinity of the human body (the basic principle of the folded dipole antenna fdp and the dipole antenna dp is the same, and therefore, the dipole antenna dp is shown for simplicity).

Normally, the current i1 as shown in the figure flows with respect to the dipole antenna dp, and the radio wave v is radiated. In this case, if there is human skin or the like in the vicinity of the dipole antenna, the dipole antenna dp is formed on the surface of the human body made of a conductor. The current i2 flowing in the opposite direction to the current i1 flowing in is generated. As a result, the currents i1 and i2 cancel each other out, so that the current i1 becomes difficult to flow through the dipole antenna dp, so that the radio wave v does not fly sufficiently.

In addition, not only a frequency band such as the UHF band, but also a ground plane antenna, which is a flat antenna, is widely used as an antenna for IC tag cards.

16 is a diagram illustrating a ground plane antenna. The ground plane antenna 300 forms a GND plate (ground plane) 302 on one surface (rear surface) of the dielectric substrate 301, and radiates on the other surface (surface) of the dielectric substrate 301. An antenna having a structure in which 303 is formed (for example, although not shown in FIG. 16 in power feeding, a core line, which is an inner conductor of the coaxial cable, is connected to the radiating element 303, and the outer conductor of the coaxial cable is GND). Connected to the plate 302 to feed a high frequency signal).

The ground plane antenna 300 has a front and back surface as described above. However, when the front side where the radiating element 303 is installed is directed toward the human body, the same phenomenon as described above with reference to FIG. 15 occurs. ), There is a problem that radiation of radio wave v is blocked and absorbed by the human body, and the radiation and reception characteristics of radio wave v deteriorate.

On the other hand, in the RFID service, as described above, not only one frequency band is communicated, but in the present state, a plurality of frequency bands such as UHF band and 13.56 MHz band are mixed to serve.

For this reason, a UHF band card, a 13.56 MHz band card, etc. also exist in a card, and when a person carries a card, it is expected that cards of these different frequency bands are mixed and stored in a wallet or a pass case.

However, in this situation, the IC tag included in the 13.56 MHz band card is electromagnetic induction, as described above in Fig. 13, so that a separate UHF band card or a 2.45 dB band is superimposed on the front or the back of the loop antenna. When stored, the magnetic field generated by the loop antenna is prevented from passing by other overlapping IC tags, and no current is generated on the loop, and the 13.56 MHz band IC tag cannot be operated and communication becomes impossible. There was.

For example, when a 13.56 MHz band card is stacked in a pass case while the 13.56 MHz band card and the UHF band card are stacked, the 13.56 MHz band card is formed by the conductor portion inside the UHF band card. In this case, radio waves that must be radiated or received are inhibited.

This invention is made | formed in view of such a point, Comprising: It aims at providing the tag apparatus which performs high quality wireless communication, without degrading the radiation / reception characteristic of a radio wave in the human body vicinity, and not interfering with the communication of another IC tag. do.

Further, another object of the present invention is to provide an antenna that performs high-quality wireless communication without deterioration of radio wave radiation and reception characteristics in the vicinity of the human body and without impairing the communication of other IC tags.

Still another object of the present invention is to provide a portable card which performs high-quality wireless communication without deterioration of radio wave radiation and reception characteristics in the vicinity of the human body and without interfering with communication of other IC tags.

Means for solving the problem

In this invention, in order to solve the said subject, in the tag apparatus 1 which performs wireless communication as shown in FIG. 1, it is a loop-shaped metal foil mounted on the surface of the dielectric substrate 30, and transmits and receives radio waves. An antenna part 10 comprising a main loop part 11 and a metal foil connected to the main loop part 11 and having a capacitive load part 12 having a load of a capacitance component, a main loop part 11 and A tag device 1 is provided, which has a control unit 20 for connecting and controlling information through radio waves.

Here, the main loop part 11 is a loop-shaped metal foil mounted on the surface of the dielectric substrate 30 to transmit and receive radio waves. The capacitive load part 12 is a metal foil connected to the main loop part 11, and has a load of a capacitance component. The control unit 20 is connected to the main loop unit 11 and controls information through radio waves.

Effect of the Invention

The tag device of the present invention is a loop-shaped metal foil mounted on the surface of a dielectric substrate, and includes a main loop portion for transmitting and receiving radio waves, a metal foil connected to the main loop portion, and a capacitive load portion having a load of capacitance component. It was set as the structure which has an antenna part. This makes it possible to perform high-quality wireless communication in the vicinity of the human body without deteriorating the radiation / reception characteristics of radio waves and without disturbing the communication of other IC tags.

The antenna of the present invention is a loop-shaped metal mounted on the surface of a dielectric substrate, and is a capacitive load section having a main loop section for transmitting and receiving radio waves and a metal connecting to the main loop section, and having a load of capacitance component. Configured. This makes it possible to perform high-quality wireless communication in the vicinity of the human body without deteriorating the radiation / reception characteristics of radio waves and without disturbing the communication of other IC tags.

The portable card of the present invention is a loop-shaped metal foil mounted on the surface of a dielectric substrate, a main loop portion for transmitting and receiving radio waves, and a metal foil connected to the main loop portion, and a capacitive load having a load of capacitance component. It has an antenna section composed of parts and is constituted by a card-shaped member which can be carried by a person. This makes it possible to perform high-quality wireless communication in the vicinity of the human body without deteriorating the radiation / reception characteristics of radio waves and without disturbing the communication of other IC tags.

These and other objects, features and advantages of the present invention will become apparent from the following description taken in conjunction with the accompanying drawings which illustrate preferred embodiments as examples of the invention.

1 is a principle diagram of a tag device.

2 shows an overview of an antenna unit.

3 is a diagram illustrating a current flowing in the antenna unit.

4 is a view for explaining the operation of the main loop unit when the tag device is located near the human body.

5 is a conceptual diagram showing the electric field strength of radio wave propagation in the UHF band.

6 is an experimental comparison of electric field strength of radiated electromagnetic waves with and without a capacitive load.

7 is a diagram showing an aspect in which the length of the capacitive load portion is changed.

8 shows the impedance of the main loop portion;

Fig. 9 shows a tag device in the case of overlapping with an ID card having a magnetic tape.

Fig. 10 is a diagram showing a tag device when overlapping with a 13.56 MHz band card.

11 is a diagram illustrating a modification of the antenna unit.

12 illustrates the concept of a propagation method;

13 illustrates the concept of an electromagnetic induction scheme.

14 illustrates a folded dipole antenna.

Fig. 15 is a diagram showing a problem of the conventional UHF card.

16 illustrates a ground plane antenna.

<Best Mode for Carrying Out the Invention>

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of this invention is described with reference to drawings. 1 is a principle diagram of a tag device. The tag device 1 is composed of an antenna unit 10, a control unit 20, and a dielectric substrate 30, and is a device that performs wireless communication. For example, the tag device 1 is used as an UHF-to-IC tag of RFID.

The antenna section 10 is composed of a main loop section 11 and a capacitive load section 12. The main loop part 11 is a loop-shaped metal foil mounted on the surface of the dielectric substrate 30 and transmits and receives radio waves (the main loop part 11 becomes a main part of the antenna function). The capacitive load part 12 is a metal foil connected to the main loop part 11, and has a load of a capacitance component.

Here, as shown in the figure, the antenna portion 10 has a shape of an elongated loop having an area smaller than that of the dielectric substrate 30, and the main loop portion 11 is formed between the dielectric substrates 30. To cover the surface of the dielectric substrate 30 (both the front and back surfaces) and the side surfaces thereof, it is mounted in a horizontal direction with respect to the surface of the dielectric substrate 30.

The capacitive load portion 12 is formed at both ends of the main loop portion 11 (also referred to as an end of the dielectric substrate 30) covering the surface on the front side of the dielectric substrate 30. However, the capacitive load portion 12 is similarly formed at both ends of the main loop portion 11 on the side of the dielectric substrate 30 (the capacitive load portion 12 is also formed on the dielectric substrate 30). Not formed on the side of the).

The control unit 20 is an electronic circuit component that is connected to the main loop unit 11 and controls information through radio waves, and corresponds to an IC chip. The control part 20 is actually mounted on the main loop part 11 (it is mounted in the center of the main loop part 11 in FIG. 1).

In addition, the control of the information is to perform the demodulation process or the data writing process to the internal memory on the information received from the main loop unit 11 (from the reader / writer) or through the main loop unit 11. The information to be transmitted (to the reader / writer) refers to performing data reading processing, modulation processing, or the like of the internal memory. In addition, since the tag device 1 obtains a power source by the above-described propagation method, the control unit 20 becomes a wave source (feeding unit), and a rectifier circuit is also included therein.

2 is a diagram illustrating an overview of the antenna unit 10. The main loop part 11 has the shape of an elongate loop, and the capacitive load part 12 is formed in the both ends of the main loop part 11. In addition, the capacitive load portion 12 is vertically connected to both ends of the loop-shaped main loop portion 11 so that the antenna portion 10 becomes an antenna having an H-shaped structure. In addition, the tag device 1 has a structure in which the dielectric substrate 30 shown in FIG. 1 is sandwiched between the antenna units 10 having such a shape.

3 is a diagram illustrating a current flowing through the antenna unit 10. The figure which simulates the electric current which flows through the antenna part 10 is shown by the arrow in which the electric current flows. During radiation and reception of radio waves, a current flows through the antenna section 10. Most of the current flows on the main loop section 11 (loop shape, so that the front and rear surfaces are looped). Flow) and the current flowing through the capacitive load portion 12 is small.

Next, the problem and effect solved by the tag apparatus 1 are demonstrated. By having the antenna unit 10 described above with reference to FIGS. 2 and 3, the tag device 1 solves the problems conventionally associated with the UHF-to-IC tag, and provides the effects of the following (1) to (4). To get.

(1) Even when the tag device 1 is used in the vicinity of the human body, good radio wave radiation and reception characteristics can be obtained.

(2) Since the impedance of the antenna (main loop section 11) can be easily adjusted, impedance matching with the IC chip (control section 20) can be achieved efficiently.

(3) Even when placed in the vicinity of an object that obstructs the radiation and reception of radio waves, radio interference can be minimized.

(4) Even if the tag device 1 is superimposed on the 13.56 MHz band IC tag, the magnetic flux generated in the 13.56 MHz band IC tag is not disturbed, which does not adversely affect the communication of the 13.56 MHz band IC tag.

In addition to the above effects, the tag device 1 has a feature that wideband communication is enabled as compared with a conventional UHF-to-IC tag. Hereinafter, the function and operation | movement of the tag apparatus 1 which concerns on these characteristics are demonstrated in detail.

In addition, the tag device 1 is used as a portable card by storing the antenna unit 10 and the control unit 20 in a card-shaped member which can be carried by a person. For example, an ID card, a cash card, a railway Widely available, such as a commuter pass card.

In addition, a card-like member may be made of a material such as plastic, for example, the antenna unit 10 may be housed inside the member, or may have a structure bonded to the member surface.

However, since the card size is set to 54 mm (length) x 86 mm (width) x 0.76 mm (thickness) in Japan, the tag device 1 becomes the size which fits in this card size.

Next, the operation of the tag device 1 in the vicinity of the human body will be described. 4 is a view for explaining the operation of the main loop portion 11 when the tag device 1 is located near the human body. The main loop part 11 of the tag device 1 is shown in the vicinity of the human body.

The main loop part 11 is a loop which consists of lines L1-L4, and an electric current flows in the counterclockwise direction at the time of the radiation and reception of an electric wave. For the sake of explanation, the current flowing through the line L1 is indicated by the current I1, the current flowing through the line L2 as the current I2, the current flowing through the line L3 as the current I3, and the current flowing through the line L4 as the current I4.

When the current flows by looping in the main loop portion 11, when the current I1 flows downward in the line L1 parallel to the human body surface, the current flows upwardly in the opposite direction to the current I1 toward the human body surface. Current I1a occurs. With respect to the line L2, when the current I2 in the right direction flows in the line L2 located perpendicular to the human body surface, the current I2a in the same right direction that flows continuously in the direction in which the current I2 flows is generated on the human body surface.

In addition, with respect to the line L3, when the electric current I3 flows upward in the line L3 located parallel to a human body surface, the electric current I3a which flows downwards opposite to the electric current I3 will generate | occur | produce toward a human body surface. With respect to the line L4, when the leftward current I4 flows in the line L4 located perpendicular to the human body surface, the same leftward current I4a that flows continuously in the direction in which the current I4 flows is generated on the human body surface.

When such a current distribution occurs, the current I1 flowing in the line L1 closest to the human body surface and the current I1a generated on the human body surface cancel each other out. In this way, a new loop-shaped current distribution is generated between the human body surface and the main loop portion 11, and equivalently, a new loop antenna RP is generated through the human body surface.

Therefore, even when the portable card including the tag device 1 is placed in the breast pocket, even if it is held close to the reader / writer by hand, the radiation / reception characteristic of the radio wave is not impaired by the human body, so that it is near the human body. Even if the tag device 1 is used, it is possible to obtain good radiation and reception characteristics of radio waves.

Next, the broadband communication realized by forming the capacitive load unit 12 in the main loop unit 11 will be described. 5 is a conceptual diagram showing the electric field strength of radio wave propagation in the UHF band. The vertical axis represents electric field strength of the radio wave and the horizontal axis represents frequency (MHz).

The graph G1 shows a state of a narrow band centered on 953 MHz as the UHF band, and the graph G2 shows a state of a wide band centered on 953 MHz as the UHF band (graph G2 shows a capacitive load unit ( 12), which is the electric field intensity distribution state of the present invention which is wideband in the UHF band).

In the RFID communication in the UHF band, the band of 952 MHz to 954 MHz is used as described above. However, the antenna does not mean that sufficient current flows as much as 952 MHz to 954 MHz as shown in the graph G1, so that radio waves can be radiated. As shown in the graph G2, it is better to make an antenna capable of sufficient radio emission over a wide range of frequencies, centering on 952 MHz to 954 MHz.

This is because, at the time of manufacture of the product, the frequency fluctuates due to a change in the material, so that even if the frequency fluctuates somewhat, the antenna that operates with good accuracy is preferable. In the tag device 1, by connecting the capacitive load unit 12 to the main loop unit 11, wideband is enabled.

6 is an experimental comparison of the electric field strength of radiated electromagnetic waves with or without the capacitive load unit 12. The vertical axis represents electric field strength E (dBμV / m), and the horizontal axis represents frequency (Hz) (in addition, αE + β = α × 10β). The electric field strength is calculated by simulation by the moment method at a value 2 m away from the tag device 1.

In addition, the dimension of the tag apparatus 1 used for calculation is 4.5 cm x 7.5 cm x 0.5 mm, and the electrical characteristics of the dielectric substrate 30 are dielectric constant 3.9 and dielectric loss 0.008. In addition, the internal impedance of the control part 20 used as a wave source was 20 ohms-180 johms, and it was set as the voltage source of 1V.

As can be seen from FIG. 6, the graph G3 showing the electric field strength of the main loop part 11 when the capacitive load part 12 is connected is the main in which the capacitive load part 12 is not connected. It can be seen that the band is wider than the graph G4 indicating the electric field strength of the loop portion 11.

Next, the impedance matching of the main loop part 11 and the control part 20 is demonstrated. The control unit 20 is connected to the main loop unit 11, and the electric power output by the control unit 20 becomes a radio wave through the main loop unit 11 and is discharged into the air.

On the main loop portion 11, the traveling wave is transmitted while maintaining the relationship of voltage / current = impedance (characteristic impedance) Z everywhere, but when the load resistance R _L having a value equal to the impedance Z is connected, all the traveling waves are the load resistance R _It enters _L , becomes heat, is consumed, and reflection from a load does not occur.

That is, when the impedance of the main loop part 11 and the internal impedance of the control part 20 are equalized (when matched), only the traveling wave output from the control part 20 is transmitted, and the power energy which the traveling wave has is all It is supplied to the main loop portion 11 which is an antenna and is radiated. However, perfect matching of impedance is an ideal state theoretically possible, and in actual design, how close to this abnormal state becomes important.

Here, the experimental measurement result at the time of changing the impedance of the main loop part 11 by changing the area of the capacitive load part 12 is demonstrated. In order to change the area of the capacitive load part 12, it is easy to cut (cut) a part of the capacitive load part 12, and to change length.

FIG. 7: is a figure which shows the aspect which changes the length of the capacitive load part 12. As shown in FIG. The length L of the part shown in FIG. 7 is varied with respect to the capacitive load part 12 in the range of 0-20 mm.

8 is a diagram showing the impedance of the main loop section 11. The vertical axis represents impedance (Ω), and the horizontal axis represents length L (mm) of the capacitive load portion 12, and the change in the impedance of the main loop portion 11 when the length L shown in Fig. 7 is varied from 0 to 20 mm. Indicates.

As can be seen from FIG. 8, the impedance is changed by changing the length L of the capacitive load portion 12. Here, assuming a simple case, if the internal impedance of the control unit 20 is obtained from 120 Ω + j320 Ω from the network analyzer measurement result, the impedance when the length L of the capacitive load unit 12 is 15 mm Matches.

Impedance Z can be expressed in the form of Z = R ± jX where R is the real part and X is the imaginary part when the resistance (resistance component) is R and the reactance (capacitive component by capacitor or coil) is X. (The sign of ± is that the impedance of the _IC is Z _IC = R _IC -jX _IC and the impedance of the antenna is Z _A = R _A + jX _A ).

As described above, in the tag device 1 of the present invention, since the impedance of the main loop portion 11 can be changed only by changing the area of the capacitive load portion 12, the control portion 20 (IC chip in advance). ) Is measured by a network analyzer or the like, and the area of the capacitive load unit 12 is changed to substantially match this measured value, whereby impedance matching can be efficiently performed. Since there are two parameters of R and reactance X, it is difficult to match both in practice. However, if the length of the capacitive load unit 12 is adjusted to match the reactance X side first, the accuracy of impedance matching is increased. Was experimentally recognized).

Next, the tag apparatus 1 in the case of being placed in the vicinity of an object which obstructs the radiation and reception of an electric wave is demonstrated. 9 is a diagram showing the tag device 1 in the case of overlapping with an ID card having a magnetic tape. When the ID card and the tag device 1 overlap, when the magnetic tape of the ID card and the main loop portion 11 of the tag device 1 overlap at the same position, radio wave interference occurs.

Therefore, in the tag device 1, the main loop section 11 includes a magnetic tape (an object that prevents radiation and reception of radio waves, not limited to the magnetic tape) so that the interaction with the magnetic tape is minimized. It is formed on the dielectric substrate 30 so as to be at a position away from the position.

Next, the tag apparatus 1 in the case of overlapping with a 13.56 MHz band card will be described. FIG. 10 is a diagram showing the tag device 1 when overlapping with a 13.56 MHz band card. As described above, a loop antenna exists inside the 13.56 MHz band card to generate magnetic flux. When the main loop portion 11 of the tag device 1 is located at the center of the card and overlaps with the 13.56 MHz band card, the flow of magnetic flux is interrupted and the reading of the 13.56 MHz band card is disturbed. 11) will cause radio interference).

Therefore, in the tag device 1, the main loop portion 11 is located at a position away from the loop antenna center portion of the 13.56 MHz band card so that the 13.56 MHz band card does not interfere with the flow of magnetic flux generated. (In the figure, the main loop portion 11 in the center of the card is moved to the end of the card).

Next, a modification of the antenna unit 10 will be described. 11 is a diagram illustrating a modification of the antenna unit 10. The antenna portion 10 described above was an antenna having a H-shaped structure in which the capacitive load portions 12 were vertically connected to both ends of the loop-shaped main loop portion 11, but the antenna portion of the modified example ( In 10a), the ends of the capacitive load part 12 are connected at an acute angle in the up-down direction of both ends of the loop-shaped main loop part 11 to have an N-shaped structure.

In addition, when the antenna portion 10a is mounted on a dielectric substrate (not shown), the main loop portion 11 of the antenna portion 10a has a shape of an elongated loop having an area smaller than that of the dielectric substrate. The dielectric substrate is sandwiched between the surface and the side of the dielectric substrate so as to sandwich the dielectric substrate, and is mounted in an oblique direction with respect to the surface of the dielectric substrate.

The capacitive load portion 12 is formed at both ends of the main loop portion 11 covering the surface on the front side of the dielectric substrate and at both ends of the main loop portion 11 covering the surface on the back side of the dielectric substrate (Fig. Although not shown, the dielectric substrate is sandwiched between two N-shaped antennas, except that the main loop portion 11 loops the front and back through the side surface of the dielectric substrate, and the capacitive load portion 12 Not formed on the sides).

When storing the tag device 1 in a card (54 mm (length) x 86 mm (width) x 0.76 mm (thickness) in a predetermined size) in Japan, the length (antenna length) of the main loop portion 11 is determined. In order to increase, it may be an N-shaped antenna as in the modification, and the same effects as those of the H-shaped are obtained.

As described above, according to the tag apparatus 1 and the portable card in which the antenna unit 10 including the main loop unit 11 and the capacitive load unit 12 is provided in a thin card, the human body overlaps with another ID card or the like. Even in the attached state, good transmission and reception characteristics can be obtained. In addition, even if it overlaps with an IC tag card of 13.56 MHz band, it is possible to adjust the matching with the IC chip (control unit 20) by changing the area of the capacitive load without adversely affecting it. For this reason, it is possible to provide an effective RFID service when promoting IT and automation in all future industries.

In addition, although the present invention has been described above as being used for a UHF band card, the present invention is not limited to the UHF band, and the principles of the present invention can be widely applied to other frequency bands.

In addition, in the above description, the tag device 1 is applied to an RFID portable card, and the shape of the antenna portion 10 is H-shaped or N-shaped. However, the antenna portion 10 is H-shaped or N-shaped. The main loop portion 11 and the capacitive load portion 12 may be connected to each other so as to have a shape other than the shape thereof, and is not limited to the RFID field, but also in other communication fields using high frequency. A wide range of applications is possible.

The above briefly describes the principles of the present invention. Also, many modifications and variations are possible to those skilled in the art, and the present invention is not limited to the exact construction and application examples shown and described above, and all corresponding modifications and equivalents are included in the appended claims and their equivalents. By the scope of the present invention.

<Code description>

1: tag device

10: antenna unit

11: main loop section

12: capacitive load part

20: control unit

30: dielectric substrate

Claims (26)

In a tag apparatus for performing wireless communication, A loop-shaped metal foil mounted around the surface and side surfaces of the dielectric substrate with a dielectric substrate interposed therebetween, a main loop portion for transmitting and receiving radio waves, and a metal foil connected to the main loop portion, and having a load of a capacitance component. An antenna unit comprising a capacitive load unit having A control unit connected to the main loop unit and controlling information through the radio wave Tag device having a. The method of claim 1, The main loop portion has a shape of a loop having a surface area smaller than the surface area of the dielectric substrate, is mounted in a horizontal direction with respect to the surface of the dielectric substrate, and the capacitive load portion covers the surface of one surface of the dielectric substrate. And the opposite ends of the loop portion and opposite ends of the main loop portion covering the other surface of the dielectric substrate. The method of claim 1, The main loop portion has a shape of a loop having a surface area smaller than that of the dielectric substrate, and is mounted in an oblique direction with respect to the surface of the dielectric substrate, and the capacitive load portion covers the surface of one surface of the dielectric substrate. And the opposite ends of the loop portion and opposite ends of the main loop portion covering the other surface of the dielectric substrate. The method of claim 1, When located near the human body, the antenna unit generates a loop-shaped current distribution between the human body surface and the main loop portion by the current flowing through the main loop portion, and equivalently becomes a loop antenna through the human body surface. The tag device characterized by the above-mentioned. The method of claim 1, And the antenna portion makes the electric field strength of the radio wave transmitted and received by the main loop portion wideband by connecting the capacitive load portion to the main loop portion. The method of claim 1, And the capacitive load part is formed on the dielectric substrate with an area adjusted to match the impedance of the control part with the impedance of the main loop part. The method of claim 1, And the main loop portion is formed on the dielectric substrate in a position where the main loop portion does not overlap with the object when placed in the vicinity of an object that prevents radiation and reception of the radio wave. The method of claim 1, When placed near a device that conducts electromagnetic induction, the main loop portion is formed on the dielectric substrate at a position that does not overlap with the magnetic flux generated by the electromagnetic induction. In the antenna which radiates and captures radio waves, When mounted on a dielectric substrate, it is a loop-shaped metal mounted so that the surface and side surfaces of the said dielectric substrate may be circumferentially interposed between the said dielectric substrate, and the main loop part which transmits and receives the said radio wave, A capacitive load portion which is a metal connected to the main loop portion and has a load of capacitance component Antenna having a. In a portable card for wireless communication, A loop-shaped metal foil mounted around the surface and side surfaces of the dielectric substrate with a dielectric substrate interposed therebetween, a main loop portion for transmitting and receiving radio waves, and a metal foil connected to the main loop portion, and having a load of a capacitance component. An antenna unit comprising a capacitive load unit having A control unit which is connected to the main loop unit and controls information through the radio wave; A card-shaped member including the antenna unit and the control unit and portable by a person Portable card, characterized in that having a. delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete

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