JP2008042734A - Rfid data carrier and rfid data carrier supporting member - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an RFID data carrier and RFID data carrier supporting member in which handleability is improved, sensitivity is made excellent and a recognition distance is long. <P>SOLUTION: The RFID data carrier is composed of an insulated support 12 formed in a plate shape, an IC unit 14 mounted on the support 12 while including a communication circuit for communicating data by a radio wave from an external reader/writer and a memory cell for storing data to be read/written, and a conductive antenna unit 16 connected to the IC unit 14 and provided on the support 12. The antenna unit 16 is composed of a radiator 20 which is composed of a linear conductive material and connected to the IC unit 14, and reflectors 22 of conductive materials in a linear shape positioned in parallel at both sides of the radiator 20. Each reflector 22 is longer than the radiator 20 and an interval between each reflector 22 and the radiator 20 is set to the 1/2 to 1/4 wavelength of a radio wave to be used. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an RFID data carrier in which various types of data are transmitted and received by radio waves in a non-contact manner and a support member for the RFID data carrier.

  2. Description of the Related Art Conventionally, as a method for managing various data related to goods such as goods and luggage, there is a system provided with a transceiver called an RFID (Radio Frequency Identification) data carrier as a tag attached to the goods. This system using an RFID data carrier includes a read / write device that reads and writes information on the RFID data carrier, transmits radio waves controlled by the controller from the antenna of the read / write device, and does not contact the RFID data carrier. Then, read and write various data. As another example of this system, it is also used for entrance / exit management to lock and unlock the gate by holding the RFID data carrier over the antenna of the reading / writing device installed near the gate side of the entrance of a parking lot or building. Yes.

  The structure of the RFID data carrier is such that an IC part and an antenna part, in which data is recorded and provided with a transmission / reception circuit, are mounted on a card-like support made of synthetic resin or the like. In addition, as the shape of the antenna portion, various pattern shapes are known for extending the recognition distance and stabilizing the operation.

  For example, as the shape of the antenna portion, there is a dipole antenna type having a pair of dipole elements extending on the same straight line with the IC portion as the center, as disclosed in the prior art of Patent Document 1. In addition, a linear radiator having an IC portion is provided, and a linear waveguide shorter than the radiator and a linear reflector longer than the radiator are arranged at equal intervals on both sides of the radiator. There is a three-element Yagi antenna type arranged and formed in parallel. Furthermore, a bi-directional Yagi antenna comprising a linear radiator having an IC portion, in which linear waveguides of the same length shorter than the radiator are arranged in parallel at equal intervals on both sides of the radiator There is also a type.

  Further, the invention of Patent Document 1 discloses RFID data that can adjust the strength of antenna directivity by appropriately setting the line length, line width, and interval of the radiator and the waveguide of the antenna unit. The carrier is disclosed.

In addition, Patent Document 2 discloses an RFID data carrier having a base material that reduces a reduction in communication distance because the base material as a support material does not absorb water. Further, in Patent Document 3, a slave station side antenna having high reception / transmission sensitivity that is stably recognized even when the distance between the tag, which is an RFID data carrier, and the antenna is located in a wider range or a long distance is formed. An RFID tag antenna structure is disclosed.
JP 2006-67478 A Japanese Patent Laying-Open No. 2005-71179 JP 2002-151947 A

  In a conventional entrance / exit management system using a general RFID data carrier, the antenna of the reading / writing device is installed near the entrance side, and when entering the room, a door is received by exchanging signals with the RFID data carrier formed in a card shape. To unlock. At this time, the card surface of the RFID data carrier is held in parallel with the antenna surface of the reading / writing device, but the recognizable distance is short and erroneous recognition is likely to occur.

  Further, in the case of the antenna structure disclosed in the prior art of Patent Document 1 and Patent Documents 1 to 3, the RFID data carrier card surface is perpendicular to the antenna surface of the read / write device, and the RFID data carrier antenna is It is necessary to face the card so that it is aligned in parallel with the antenna surface of the reading / writing device. However, the operation of directing the card in such an arrangement is difficult to use unlike the conventional general system in which the card surface is recognized in parallel with the antenna surface of the reading / writing device.

  The present invention has been made in view of the above problems of the prior art, and an object thereof is to provide an RFID data carrier and an RFID data carrier support member that are easy to use, have good sensitivity, and have a long recognition distance.

  The present invention includes an insulating support formed in a plate shape, a communication circuit that performs data communication using radio waves from an external read / write device, and a storage element that stores data in a readable / writable manner. An RFID data carrier comprising an IC part attached to the IC part and a conductive antenna part connected to the IC part and provided on the support, wherein the antenna part is made of an elongated conductive material such as a straight line. The radiator is connected to the IC part, and is formed of a reflector of a linear conductive material such as a straight line located parallel to both sides of the radiator, the reflector being formed longer than the radiator, In the RFID data carrier, the distance between the reflector and the radiator is set to a length of ½ to ¼ of the wavelength of the used radio wave.

  The distance between the radiator and the reflector is set to a length of about 0.4 to 0.5 times the wavelength of the used radio wave. Alternatively, the interval between the radiator and one of the reflectors is set to about 0.3 times the wavelength of the used radio wave, and the interval between the radiator and the other reflector is set to the wavelength of the used radio wave. The length is set to about 0.4 times.

  In addition, the present invention is provided with reflectors of elongated conductive materials such as straight lines positioned parallel to each other on both sides of the surface of the insulating support formed in a plate shape, and external readings are provided between the reflectors. An IC unit attached to the support body having a communication circuit for communicating data by radio waves from the writing device and a storage element for storing data in a readable and writable manner, and a straight line connected to the IC part and provided on the support body A radiator made of an elongated conductive material such as a shape is formed so as to be able to be stacked, and the reflector is formed longer than the radiator and is located in parallel with each other, and the distance between the reflector and the radiator Is a support member for an RFID data carrier set so as to be 1/2 to 1/4 of the wavelength of the used radio wave.

  According to the RFID data carrier and the RFID data carrier supporting member of the present invention, reading or writing can be performed by holding the surface of the RFID data carrier formed in a card shape substantially parallel to the antenna surface of the reading / writing device. Like a typical card-like RFID data carrier, it is easy to use. Furthermore, the antenna gain increases and the communicable distance becomes longer, making it easier to use.

  Hereinafter, a first embodiment of the RFID data carrier of the present invention will be described with reference to FIGS. As shown in FIG. 1 and the like, the RFID data carrier 10 is obtained by mounting an IC portion 14 and an antenna portion 16 formed of a conductive material on a surface of a support material 12 formed in a rectangular card shape. .

  The communication method of the RFID data carrier 10 employs a method using a microwave wave having a frequency of 2.45 GHz band, and a communication distance compared to other communication methods such as an electrostatic coupling method and an electromagnetic induction method. Is relatively wide. Then, by transmitting a microwave radio wave controlled by an external read / write device controller (not shown) from the antenna of the read / write device, and receiving the transmitted radio wave by the antenna unit 16 of the RFID data carrier 10, Various data is transmitted and received between the reading / writing device and the RFID data carrier 10 in a contactless manner.

  As shown in FIGS. 1A and 1B, the support body 12 of the RFID carrier 10 of this embodiment is made of a plate material made of an insulating material such as paper or synthetic resin. In addition, plastic, polyethylene, vinyl chloride, acetate, polycarbonate, acrylic, and other synthetic resins, bakelite, micalex, glass, ceramics, stone, cloth, non-woven fabric, etc. can be formed into a flat plate in the form of a card or film at room temperature. Things are used. An antenna portion 16 is provided on one surface of the support 12.

  The IC unit 14 is formed of a thin integrated circuit chip with a built-in communication circuit and a memory as a storage element. The memory can be used as a battery-less data carrier by using an EEPROM or a flash memory.

  As shown in FIG. 2, the antenna unit 16 is located in the center of the support 12, the radiator 20 disposed in parallel with the short side of the support 12, and the distances S1 and S2 on both sides appropriately. Each reflector 22 is provided and arranged.

  The radiator 20 is provided with a power supply unit (not shown) in the vicinity of the center position thereof. The electrodes of the IC unit 14 are connected to both ends of the power supply unit, and are electrically connected to the communication circuit of the IC unit 14. The radiator 20 is made of a conductive film, and is formed of, for example, a conductive paint or metal foil containing silver paste, graphite, carbon, or the like. As shown in FIG. 2, the radiator 20 is configured by printing a pattern with a width W1 and a length L1 on the support 12, or is formed by attaching a metal foil. The radiator 20 has a function of capturing radio waves transmitted from an antenna of an external reading / writing device (not shown) and radiating radio waves toward the antenna of the reading / writing device.

  The reflectors 22 are each formed in a straight line in the vicinity of both ends in the long side direction of the support 12 at positions parallel to the short sides. In addition, the reflector 22 is made of a conductive film, similar to each radiator 20, and as shown in FIG. 2, for example, a conductive paint containing silver paste, graphite, carbon or the like is applied onto the support 12. The pattern is printed with a width of W2 or a metal foil is pasted. The length L2 of the reflector 22 is formed longer than the length L1 of the radiator 20.

  In the embodiment of the present invention, the operating frequency f is 2448.875 MHz, and the wavelength λ is 122.5 mm. Then, as shown in FIG. 1B, the directivity of the antenna unit 16 of the RFID data carrier 10 is set in a direction perpendicular to the surface of the support 12.

  In the configuration of the radiator 20 and the pair of reflectors 22, the line length and line width of each element of the radiator 20 and the reflector 22 and the distance between the radiator 20 and each reflector 22 are set as follows, for example. . It is assumed that L1 = 43 mm and W1 = 3 mm of the radiator 20 and L2 = 62.5 mm and W2 = 2.0 mm of each reflector 22. The length L2 of the reflector 22 was experimentally set to the best value for the reflector operation. W2 is set to a width smaller than the wavelength λ. In addition, the distances S1 and S2 between the radiator 20 and the reflectors 22 are the highest sensitivity in the experiment when S1 = S2 = λ / 2, but may be within the size of a general card-type RFID data carrier, for example. And S1 = 45.5 mm and S2 = 38.0 mm.

The operations of the radiator 20 and the reflector 22 of this embodiment are equivalent to a beam antenna 24 composed of three elements fed in the same phase as shown in FIG. The reflectors 22 on both sides have a phase difference of 0.5λ, that is, 180 ° behind the distance between the radiator 20 and the reflector 22, and a further 180 ° phase lag occurs due to re-radiation. The phase difference is 360 °. That is, the phases of the radiator 20 and the reflectors 22 provided on both sides thereof are all in phase. As shown in FIG. 3, when all three elements are excited by the common-mode current I, the electric field intensity E at a far point having a sufficient distance d ₀ as compared with the wavelength is expressed by Equation (1).
E = (60I / d ₀ ) · sin (1.5πcos θ) / sin (0.5πcos θ) (1)
Note that sin (1.5πcos θ) / sin (0.5πcos θ) is for determining the directivity coefficient of the three-element beam antenna. FIG. 4 is a directivity diagram showing the electric field strength E and the directivity coefficient in a graph. As shown in FIG. 4, the antenna gain is 3 times and the directivity pattern D is formed.

  The frequency range of the present invention is theoretically applicable as long as the wavelength is in the radio wave range, but is practically 100 MHz to 10 GHz. The RFID frequency band above UHF in Japan is the 2.45 GHz band and 952 to 955 MHz. If possible, the above 100 MHz to 10 GHz is more preferable.

  According to the RFID data carrier 10 of this embodiment, the surface of the RFID data carrier 10 formed in a card shape is held in parallel with the antenna of a read / write device installed on the wall near the entrance / exit side, such as an entrance / exit management system. Since it is communicable, the convenience is not different from that of a conventional card-like RFID data carrier. Further, the distance between the radiator 20 formed on the support 12 and the reflectors 22 arranged at parallel positions on both sides thereof is set to λ / 2 to λ / 4 with respect to the wavelength λ of the used radio wave. By setting the value close to the length of the antenna, the antenna gain of the RFID data carrier 10 is improved, and even when the support 12 is held in parallel with the antenna of the reading / writing device, the communicable distance is long, and it is easily accurate. Recognition is possible.

  Next, a second embodiment of the present invention will be described with reference to FIG. Here, the same members as those in the above embodiment are denoted by the same reference numerals, and the description thereof is omitted. This embodiment is for an RFID data carrier support member 30 comprising a support 12 formed in a rectangular and plate shape made of an insulating material, and is linear in the vicinity of both ends in the long side direction and in parallel with the short sides. The reflectors 22 are arranged respectively. The reflector 22 is formed in advance by a conductive paint by printing or the like on the support 12 or is formed by attaching a metal foil. A radiator and an IC unit are attached to the support 12 at the center of the support in parallel to the reflectors 22 later.

  According to the RFID data carrier support member 30 of this embodiment, the RFID data carrier support member 30 that improves the communication sensitivity of the existing RFID data carrier formed by the IC portion and the radiator is formed. The communication distance of the RFID data carrier can be easily extended. Furthermore, since communication is possible by holding the surface of the RFID data carrier supporting member 30 parallel to the antenna of the reading / writing device, the usability is also good.

  The RFID data carrier of the present invention is not limited to the above-described embodiment, and it is sufficient that reflectors are formed in parallel at regular intervals on both sides of the radiator, and the reflector is formed longer than the radiator. The radiator and the reflector may be formed in an elongated shape other than a straight shape, may be curved, and the width and length can be appropriately set depending on the frequency used. In addition, the shape and material of each member can be appropriately changed.

  Table 1 shows the reading experiment data of the RFID data carrier 10 according to one embodiment of the present invention. In this experiment, as shown in FIG. 6, the RFID data carrier 10 is attached to a cardboard box 26 and is disposed so as to be opposed to an antenna 18 of a read / write device (not shown). Then, the maximum communicable distance d by which the reading / writing device recognizes the RFID data carrier 10 was measured. The radiator 20 and the reflector 22 constituting the antenna of the RFID data carrier 10 are, as shown in Table 1 in each dimension of FIG. 2, the width W1 and the length of the radiator 20 used for a general card type. W1 = 3 mm and L1 = 43 mm. Moreover, the width W2 of the reflector 22 was fixed to W2 = 2.0 mm from the result of the experiment.

  Then, the maximum communicable distance d was measured by appropriately changing the length L2 of the reflector 22 and the intervals S1 and S2 between the radiator 20 and each reflector 22. The frequency f to be used is 2448.875 MHz and the wavelength λ is 122.5 mm. From this frequency and wavelength, the optimum values of theoretical S1 and S2 of the radiator 20 and each reflector 22 are λ / 2 = 61. .3 mm or λ / 4 = 30.6 mm. The measurement results of this experiment are shown in Table 1. In Table 1, (ki) is a configuration in which the antenna unit is only a radiator, and (a) to (f) are configurations having a reflector.

  According to this measurement result, as shown in FIG. 6, the maximum communicable distance d is (A) when the distance to each reflector 22 provided on both sides of the radiator 20 which is the same as the theoretical value is λ / 2. 2250 mm. In addition, in the RFID data carrier 10 (e) formed on a card-type support 12 having a general size, the maximum communicable distance d is 2150 mm, and in Table 1, the second longest maximum communicable is possible. It was a distance and had a sufficient communication distance. In the example of (e), the card of the support can be made smaller, which is more practical.

  Also, in (A) and (C), the maximum communicable distance d that is about twice that of the configuration of only the antenna unit was obtained. In addition, in (F), the distance between S1 and S2 is different as in (E), and the length of the reflector is shorter than that in (E). Thus, a maximum communicable distance d of about twice can be obtained, and in this case as well, the support card can be made small, which is practical.

  In addition, (d) is short in S1 and S2 and can reduce the size of the support in that direction, but the effect of extending the maximum communicable distance d is small for a long reflector length, It is limited.

It is the schematic plan view (a) of the RFID data carrier of 1st embodiment of this invention, and AA sectional drawing (b). It is a top view which shows the shape of the antenna part of the RFID data carrier of this embodiment. It is a perspective view which shows the arrangement | sequence of the 3 element beam antenna for the theoretical description of the RFID data carrier of this embodiment. It is a directivity characteristic graph which shows the antenna gain and antenna directivity of the RFID data carrier of this embodiment. It is a schematic plan view which shows the support member for RFID data carriers of 2nd embodiment of this invention. It is the schematic which shows the communication distance of the RFID data carrier used for the Example of this invention, and the antenna of the reading / writing apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 RFID data carrier 12 Support body 14 IC part 16 Antenna part 20 Radiator 22 Reflector

Claims (4)

  An insulating support formed in a plate shape, a communication circuit that communicates data by radio waves from an external read / write device, and a storage element that stores data in a readable and writable manner are attached to the support. In an RFID data carrier comprising an IC part and a conductive antenna part connected to the IC part and provided on the support, the antenna part is made of an elongated conductive material and connected to the IC part, The reflector is made of an elongated conductive material positioned in parallel on both sides of the radiator, the reflector is formed longer than the radiator, and the distance between the reflector and the radiator is 1 of the wavelength of the used radio wave. RFID data carrier characterized by being set to a length of / 2 to 1/4.   2. The RFID data carrier according to claim 1, wherein an interval between the radiator and the reflector is set to a length of about 0.4 to 0.5 times a wavelength of a used radio wave.   The interval between the radiator and one of the reflectors is set to a length of about 0.3 times the wavelength of the used radio wave, and the interval between the radiator and the other reflector is set to about 0 of the wavelength of the used radio wave. 2. The RFID data carrier according to claim 1, wherein the RFID data carrier is set to be four times as long. Reflectors made of elongated conductive material positioned parallel to each other are provided on both sides of the surface of the insulating support formed in a plate shape, and data communication is performed between the reflectors by radio waves from an external read / write device. An IC part that has a communication circuit for performing data storage and a memory element that stores data in a readable and writable manner and is attached to the support body, and an elongated conductive material that is connected to the IC part and provided on the support body. Connected radiators are formed so as to be capable of being stacked, and the reflectors are formed longer than the radiators and are parallel to each other, and the distance between the reflectors and the radiators is ½ to ¼ of the wavelength of the used radio wave. A support member for an RFID data carrier, which is set to have a length of

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