JP2008186327A - Rfid reader - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain more stable and high reading performance of, for example, a card type tag in an RFID reader. <P>SOLUTION: The RFID reader 1 for at least reading data from an RFID tag T by electromagnetic induction or electromagnetic coupling is provided with a loop antenna part 3 having a loop main body part 3a with conductive wire wound around in the shape of a rectangle, a pair of antenna terminal parts 3b extending to one side of the loop main body part 3a to receive data; and a communication circuit part 4 connected to the antenna terminal parts 3b, wherein the pair of antenna terminal parts 3b is arranged at an interval larger than the width of the loop main body part 3a, extending mutually in parallel. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an RFID (Radio Frequency Identification) reader device that reads data without contact with a card-type tag or the like that incorporates an IC chip.

  In recent years, RFID (Radio Frequency Identification) technology for identifying and managing a person or an object with a minute wireless chip has attracted attention. In this RFID technology, data is stored in an RFID tag attached to a product, etc., and identification and information of the product etc. are automatically recognized and managed by communicating with an RFID reader / writer or reader wirelessly. is there. This RFID technology is being widely adopted in manufacturing, sales, distribution, or lending services to detect the location of an RFID tag-attached item or person, information such as an ID, and manage the movement of the information.

  For example, Patent Document 1 proposes a contactless card authentication system using a loop antenna with a circular coil. This circular loop antenna is copper-plated on a printed circuit board, and a pair of antenna terminals are provided extending in the same place. Patent Document 2 proposes a portable card-like reader or reader / writer having a square loop antenna. This rectangular loop antenna is obtained by patterning a conductor on a substrate, and a pair of antenna terminals are provided extending in the same place.

JP 2002-324215 A JP 2005-134942 A

The following problems remain in the conventional technology.
For example, in the case of a plurality of card-type tags in which the RFID tag has a rectangular tag-side antenna portion along the outer shape and are arranged adjacent to each other, like the technique described in Patent Document 1 above, When a circular loop antenna is used, the magnetic field distribution is inclined (change in magnetic field strength) with respect to the extending direction of the rectangular tag side antenna portion, which causes a disadvantage in that the reading performance is deteriorated. Further, even when a square loop antenna is used as in the technique described in Patent Document 2, a higher reading performance is demanded more stably.

  The present invention has been made in view of the above points, and an object of the present invention is to provide an RFID reader device having a more stable and high reading performance with respect to, for example, a card type tag.

  The present invention employs the following configuration in order to solve the above problems. An RFID reader device according to the present invention is an RFID reader device that reads at least data from an RFID tag by electromagnetic induction or electromagnetic coupling, and includes a loop body portion in which a conducting wire is wound in a rectangular shape and one side of the loop body portion A loop antenna unit that receives the data, and a communication circuit unit that is connected to the antenna terminal unit, and the pair of antenna terminal units includes the loop body unit. It is characterized by being arranged so as to extend in parallel with each other at an interval equal to or greater than the width of.

  In this RFID reader device, the pair of antenna terminals are arranged so as to extend in parallel with each other at an interval equal to or greater than the width of the rectangular loop main body, and therefore due to deformation (crossing or inclination) of the antenna terminal The reading performance of the RFID tag is improved as compared with conventional circular loop antennas and rectangular loop antennas by preventing impedance deviation and suppressing the influence on the magnetic field generated from the loop body.

  In the RFID reader device of the present invention, the conducting wire is a single metal wire. That is, in this RFID reader device, since the conducting wire is a single metal wire such as a copper wire, it is easy to maintain the shape of the loop antenna with high rigidity compared to the stranded wire, and high reading performance can be obtained.

  Further, the RFID reader device of the present invention is characterized in that the conducting wire is wound a plurality of times along the axial direction of the loop main body. That is, in this RFID reader device, the conductive wire overlaps along the axial direction of the loop main body and is wound a plurality of times, so that compared to the case where the conductor is wound a plurality of times along the opening surface of the loop main body. A stronger magnetic field can be generated in the axial direction of the main body.

  The RFID reader device of the present invention is a plurality of card-type tags in which the RFID tag has a rectangular tag-side antenna portion along an outer shape and is arranged with its surfaces adjacent to each other. The reading is performed by making the opening surface of the portion substantially orthogonal to a plane parallel to the surface of the RFID tag. For example, in a library or the like, when an RFID tag, which is a card type tag, is attached to a book and arranged on a bookshelf, and the RFID tags are arranged in a state where their surfaces are adjacent to each other, the RFID reader device of the present invention uses the loop body Reading is performed with the opening surface of the portion being substantially orthogonal to the plane parallel to the surface of the RFID tag, so that electromagnetic induction is applied to the tag-side antenna portion of the RFID tag in the vicinity of the two opposite sides of the loop main body where a high magnetic field is generated. Or it becomes easy to carry out electromagnetic coupling. Therefore, reading can be performed at two places (near the opposite two sides) of the loop main body, and high reading performance can be obtained.

The present invention has the following effects.
That is, according to the RFID reader device, the pair of antenna terminals are arranged so as to extend in parallel with each other at an interval equal to or greater than the width of the rectangular loop main body, so that the antenna terminal portion is deformed (crossed or inclined). Thus, it is possible to improve the reading performance of the RFID tag by preventing an impedance shift due to, for example, and suppressing an influence on the loop main body. In particular, when a plurality of card-type tags are arranged in a state where their surfaces are adjacent to each other, it becomes possible to read a plurality of pieces of information with high accuracy.

  Hereinafter, an RFID reader device according to an embodiment of the present invention will be described with reference to FIGS.

  As shown in FIGS. 1 and 2, the RFID reader device 1 of the present embodiment is a handy type (portable) device that reads at least data from the RFID tag T by electromagnetic induction or electromagnetic coupling. In a library or the like, an RFID tag T, which is a card type tag, is attached to a book and arranged on a bookshelf, and the RFID tag T is used in a state where the surfaces are arranged adjacent to each other.

  The RFID reader device 1 includes a device main body 2, a loop main body portion 3a in which a conducting wire such as a copper wire is wound in a square shape, and a pair of antenna terminal portions extending to one side (short side) of the loop main body portion 3a. A loop antenna unit 3 that receives data, a communication circuit unit 4 that is connected to the antenna terminal unit 3b and performs arithmetic processing related to data transmission and reception, and a data decoding process that is connected to the communication circuit unit 4 A data processing circuit unit 5 that performs the data processing, a display unit 6 such as a liquid crystal display device that is connected to the data processing circuit unit and displays the read data, a wireless antenna 7 that wirelessly transmits the read data over a wireless LAN, and the like And a communication circuit unit 8.

The loop antenna unit 3 has a function of supplying a current and forming a magnetic field for feeding power to the RFID tag T to output a power signal.
The conducting wire is, for example, a single metal wire such as a copper wire, and the conducting wire is wound a plurality of times along the axial direction of the loop body portion 3a. In the present embodiment, a copper wire having a wire diameter of 2 mm is used as the conducting wire, and the loop body 3a is configured with two windings.
The pair of antenna terminal portions 3b are arranged so as to extend in parallel with each other at an interval equal to or larger than the width of the loop main body portion 3a. In the present embodiment, the pair of antenna terminal portions 3b are set to have the same width as the loop main body portion 3a, and are arranged so that the pair of long side portions of the loop main body portion 3a are extended.

The communication circuit unit 4 is provided with an impedance matching circuit, and a trimmer capacitor (not shown) is used for the matching circuit. The Q value of this trimmer capacitor is set to 3000 or more. If the Q value is 200, sufficient performance cannot be obtained.
The communication circuit unit 4, the data processing circuit unit 5, and the wireless communication circuit unit 8 are formed on a substrate 9 stored in the apparatus main body 2. These are connected to a power supply unit (not shown) built in the apparatus main body 2 and supplied with power.

  The RFID tag T is, for example, a photo-etching or resist printing of a metal foil such as a laminated aluminum foil on a base material 10 such as paper laminated with a metal layer or various materials such as PET, polypropylene, polyethylene, polystyrene, and nylon. The tag-side antenna portion 11 having a square coil shape is formed by subsequent etching, and the both ends of the tag-side antenna portion 11 are connected to the IC chip 12 mounted on the base material 10. In addition, the tag side antenna part 11 of this embodiment uses the thing of antenna width 54mm and antenna length 86mm. The dimensions of the loop body 3a are set to be the same as or close to those of the RFID tag T, and in this embodiment, the antenna width is set to 40 mm and the antenna length is set to 100 mm.

The “RFID tag” used in the present invention may be generally expressed as “non-contact IC tag”, “non-contact IC”, “non-contact IC label”, or “non-contact data carrier”.
The RFID tag T conforms to the ISO standard and operates at 13.56 MHz, and the loop antenna unit 3 and the communication circuit unit 4 are also set to be applicable to this frequency.

  Next, the result of actually reading data from the RFID tag T using the RFID reader device 1 of the present embodiment will be described with reference to FIGS.

  First, when the RFID tag T is read by the RFID reader device 1 of the present embodiment, the reading is performed with the opening surface of the loop main body 3a substantially orthogonal to the parallel surface to the surface of the RFID tag T and a predetermined distance is opened. Do. That is, in FIG. 1, the opening surface of the loop main body 3a is parallel to the surface formed in the X direction and the Y direction orthogonal thereto, and the parallel surface to the surface of the RFID tag T is in the X direction and the Y direction. Each is parallel to the orthogonal Z direction.

  In this embodiment, as shown in FIG. 3A, a pair of antenna terminal portions 3b extending in parallel with the same width as the antenna width of the loop main body portion 3a is used (Parallel), and as a comparative example As shown in FIG. 3 (b), the wire diameter of the conducting wire is obtained when a pair of antenna terminal portions 3b crossing at the center of the short side portion of the loop main body portion 3a and extending obliquely (Cross) are used. The results of measuring the reading rate with changing φ are shown in Table 1 below. As can be seen from this result, in any of the wire diameters, the present embodiment using the parallel antenna terminal portion 3b achieves a higher reading rate than the comparative example using the intersecting antenna terminal portions. .

  In addition, as shown in FIGS. 4A to 4D, the results of evaluating the reading rate when the distance s between the pair of antenna terminal portions 3b is changed to 70 mm, 40 mm, 20 mm, and 5 mm are shown below. It shows in Table 2. In this evaluation, the antenna width of the loop body 3a was set to 40 mm. As can be seen from this result, when the distance s between the antenna terminal portions 3b is narrower than the antenna width 40 mm as in the prior art, the reading rate is lower as the distance s is smaller, but the antenna width 40 mm or more as in the present embodiment, That is, a substantially constant high reading rate of 90% or more is realized above the width of the loop body 3a.

  In addition, Table 3 below shows the results of measuring the reading rate by changing the diameter φ of the core wire between the case where the single wire of the copper wire is the conducting wire and the case where the stranded wire is the conducting wire as this embodiment. The distance h from the RFID tag T was 25 mm. As can be seen from this result, when the single wire is a conducting wire, the reading rate is 100%, whereas when the stranded wire is used, the reading rate is lower than that of the single wire.

  Table 4 below shows the reading rates when the antenna width w of the loop body 3a, the number N of turns of the conductive wire, and the distance h from the RFID tag T are changed. As can be seen from this result, under this condition, when the distance h from the RFID tag T is 25 mm, the reading rate is highest when the antenna width w is 40 mm and the number of turns is 2.

  As described above, in the present embodiment, the pair of antenna terminal portions 3b are arranged so as to extend in parallel with each other at an interval equal to or greater than the width of the rectangular loop main body portion 3a. The RFID tag reading performance is improved compared to conventional circular loop antennas and rectangular loop antennas by preventing impedance deviation due to crossing and inclination) and suppressing the influence on the magnetic field generated from the loop body 3a. To do.

  Moreover, since the conducting wire is a single metal wire such as a copper wire, the shape of the loop antenna portion 3 can be easily maintained and the reading performance can be obtained with high rigidity compared to the stranded wire. Furthermore, since the conducting wire is overlapped and wound a plurality of times along the axial direction of the loop body portion 3a, the loop body portion 3a is compared with the case where it is wound a plurality of times along the opening surface of the loop body portion 3a. A stronger magnetic field can be generated in the axial direction.

  Further, reading is performed with the opening surface of the loop main body 3a being substantially orthogonal to a plane parallel to the surface of the RFID tag T, so that the tag of the RFID tag T is located in the vicinity of the opposite two sides of the loop main body 3a where a high magnetic field is generated. Electromagnetic induction or electromagnetic coupling to the side antenna unit 11 is facilitated. Therefore, reading can be performed at two locations (near the opposite two sides) of the loop body 3a, and high reading performance can be obtained.

In addition, this invention is not limited to the said embodiment, A various change can be added in the range which does not deviate from the meaning of this invention.
The technology in the above embodiment is applied to an RFID reader device that can read data, but can also be used for an RFID reader / writer device that can read and write data.

It is a schematic block diagram which shows an RFID tag with the RFID reader apparatus of one Embodiment which concerns on this invention. It is a side view which shows an RFID tag with an RFID reader apparatus about this embodiment. It is a front view which shows a loop antenna part with the case (b) which has an antenna terminal part which cross | intersects (a) which has a parallel antenna terminal part about this embodiment. It is a front view which shows the loop antenna part of (a)-(d) when the space | interval of a parallel antenna terminal part is changed about this embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... RFID reader apparatus, 3 ... Loop antenna part, 3a ... Loop main-body part, 3b ... Antenna terminal part, 4 ... Communication circuit part, 11 ... Tag side antenna part, s ... Space | interval of antenna terminal part, T ... RFID tag, w ... Antenna width

Claims (4)

An RFID reader device that reads at least data from an RFID tag by electromagnetic induction or electromagnetic coupling,
A loop antenna unit having a loop main body wound in a rectangular shape and a pair of antenna terminal portions extending to one side of the loop main body, and receiving the data;
A communication circuit unit connected to the antenna terminal unit,
The RFID reader device, wherein the pair of antenna terminal portions are arranged to extend in parallel with each other at an interval greater than the width of the loop main body portion. The RFID reader device according to claim 1, wherein
The RFID reader device, wherein the conducting wire is a single metal wire. The RFID reader device according to claim 1 or 2,
The RFID reader device according to claim 1, wherein the conductive wire is wound a plurality of times along the axial direction of the loop main body. In the RFID reader device according to any one of claims 1 to 3,
The RFID tag is a plurality of card-type tags that have a rectangular tag-side antenna portion along the outer shape and are arranged adjacent to each other.
An RFID reader device that performs the reading by making the opening surface of the loop main body substantially orthogonal to a plane parallel to the surface of the RFID tag.

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