JP2015012510A - Rfid antenna cell and system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an array antenna for reading an RFID tag communicable between the RFID tag and an RFID antenna irrespective of the directions thereof.SOLUTION: An RFID antenna cell 10 for reading out information stored in an RFID tag 50 includes a transmission line including an inside conductor 11 extending inside an insulator 13 and an outside conductor 12 positioned on the surface of the insulator 13. On the surface of the outside conductor 12, there are continuously formed grooves 14 of tapered shapes extending at a required angle relative to the inside conductor 11.

Description

  The present invention relates to an RFID antenna cell and system, and more particularly, to an RFID antenna cell and system for reading information recorded on an RFID tag.

In Patent Document 1, an antenna for an RFID reader is attached to a shelf for storing an article to which an RFID tag is attached, and the article placed on the shelf is managed in real time by using the RFID reader to communicate with the RFID tag. A system that is convenient for inventory, etc. is disclosed. Patent Document 1 describes that an RFID tag is attached to a desired position of an article in a desired direction.
Japanese Patent No. 4986697

  By the way, the RFID tag can be used not only for an article placed on a shelf but also for management of various articles. For example, when a certain product is transported from a factory, transport management can be performed using an FRID in which information including a destination of a transport destination is stored.

  When performing such management, an FRID tag storing information including the destination address of the transport destination is affixed to the transport management card, and the transport management card is attached to a cardboard box or the like that packs the product. Insert into a plastic pocket. Then, an operation of reading information stored in the RFID tag may be performed using the RFID antenna.

  In this case, the vinyl pocket is often sized corresponding to the largest transport management card in order to realize insertion of transport management cards of various sizes. However, in this case, when a small transport management card is used, the transport management card may be tilted or fall down in the vinyl pocket.

  The direction of the RFID tag is very important for performing desired communication with the RFID antenna. The RFID reader antenna disclosed in Patent Document 1 is not designed on the assumption that the transport management card is in various orientations, that is, the RFID tag is in various orientations. It is not suitable for use under such circumstances.

  Therefore, an object of the present invention is to provide an RFID tag reading array antenna that can communicate between the RFID tag and the RFID antenna regardless of the orientation thereof.

In order to solve the above problems, the present invention provides an RFID antenna cell that reads information stored in an RFID tag.
A transmission line having an inner conductor extending inside the insulator and an outer conductor located on the surface of the insulator;
On the first surface of the outer conductor, a groove extending at a required angle with respect to the inner conductor is continuously formed in a letter C shape.

  Each groove may be formed at an angle of 30 ° to 60 ° with respect to the inner conductor.

  Each of the grooves may be linear or may have a stepped shape approximate to this.

  An RFID system according to the present invention includes the RFID antenna cell described above and an information processing apparatus that processes information received by the RFID antenna cell.

  According to the present invention, the groove extending at the required angle with respect to the inner conductor is formed continuously on the surface of the outer conductor in a letter C shape, so that it depends on the angle between the RFID tag and the RFID antenna cell. In addition, the information of the RFID tag can be read accurately.

BEST MODE FOR CARRYING OUT THE INVENTION

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic configuration diagram of an RFID tag system 100 according to an embodiment of the present invention. 1 includes a plurality of RFID antenna cells 10a to 10c, which will be described later with reference to FIG. 2, coaxial cables 20a to 20b for electrically and physically interconnecting the RFID antenna cells 10a to 10c, and an RFID antenna cell 10c. 1 shows an RFID reader 30 connected to the other end of the coaxial cable 20c to which one end is connected.

  The RFID tag system 100 shown in FIG. 1 shows an example using three RFID antenna cells 10a to 10c, but the number of RFID antenna cells 10a to 10c is not necessarily three, and the number of management objects It may be determined appropriately according to the above.

  The RFID antenna cells 10a to 10c all have the same configuration. Hereinafter, the RFID antenna cells 10a and 10c are collectively referred to as the RFID antenna cell 10 unless it is particularly necessary to distinguish them. Further, the coaxial cables 20a to 20c are longer than the other coaxial cables 10a to 20b only in the coaxial cable 20c, except for that point, and are configured in the same manner. Collectively, the coaxial cable 20 is shown.

  FIG. 2 is a perspective view showing a schematic configuration of the RFID antenna cell 10 of FIG. As shown in FIG. 2, the RFID antenna cell 10 has a rectangular parallelepiped shape. However, even if it is not a rectangular parallelepiped, its longitudinal cross section may be shaped like a bowl.

  The general shape of the RFID antenna cell 10 depends on the general shape of the insulator 13. The insulator 13 is made of a plastic having required strength and insulation. An inner conductor 11 made of a metal such as copper extends along the longitudinal direction of the central portion of the insulator 13. The surface of the insulator 13 is covered with an outer conductor 12 made of a metal foil including an aluminum foil. In other words, the RFID antenna cell 10 includes a transmission line having an inner conductor 11, an outer conductor 12, and an insulator 13. In addition, what is necessary is just to manufacture the transmission line of this embodiment on the conditions from which characteristic impedance will be about 50 (ohm).

  On the first surface of the RFID antenna cell 10, a rectangular groove 14 is continuously formed in a letter C shape. Both ends of the outer conductor 12 are connected to each other by an adhesive, soldering, or the like at the position of the second surface which is the back surface of the first surface. In addition, at least the vicinity of the connection portion of the coaxial cable 20 is open at both ends in the longitudinal direction of the insulator 13 so that the coaxial cable 20 can be connected.

  The coaxial cable 20 includes a core conductor 21 connected to the inner conductor 11 and a coated conductor 22 connected to the outer conductor 12. The coaxial cable 20 is connected to an RFID reader 30 that is an excitation source.

  When the RFID antenna cell 10 is configured as shown in FIG. 2, a radio wave for reading information based on the current flowing through the coaxial cable 20 is emitted from the groove 14 when the RFID reader 30 is turned on. Therefore, if the RFID tag is located in the vicinity thereof, the information stored in the RFID tag is read by the radio wave, so that the RFID reader 30 can acquire the information. Note that the frequency band of the radio wave employed in the RFID tag system 100 is not limited to this, but, for example, the UHF band (920 MHz) can be used.

  Here, it is necessary for the RFID antenna cell 10 shown in FIG. 2 to make the shape, size, and mutual positional relationship of each groove 14 a predetermined condition. In particular, it is necessary to form the pair of grooves 14 in a letter C shape and to form them continuously in order to communicate with the RFID tag even if the RFID tag is in various orientations.

  FIG. 3A to FIG. 3C are explanatory diagrams for explaining the reason for forming the pair of grooves 14 in a C shape. In FIG. 3A to FIG. 3C, a cardboard box 200 that packs a product to be transported, a vinyl pocket 300 provided on a side surface of the cardboard box 200, and a vinyl pocket 300 inserted into the cardboard box 300. A transfer management card 400 and an RFID tag 500 attached to the transfer management card 400 are shown. A groove 14 is also added at a position corresponding to the RFID tag 500.

  As shown in FIG. 3 (a), the transport management card 400 has an original orientation when inserted into the vinyl pocket 300, and an oblique orientation as shown in FIG. 3 (b). As shown in FIG.3 (c), it may become the direction which fell down.

  As shown in FIG. 3A, if it is certain that the transport management card 400 is in the original orientation in the vinyl pocket 300, the RFID tag 500 is in the horizontal direction of the drawing. Ideally, it is formed so as to extend in the vertical direction of the drawing so as to be orthogonal to the direction of the RFID tag 500.

  However, when the transport management card 400 is smaller than the vinyl pocket 300, the transport management card 400 is inclined in the vinyl pocket 300 as shown in FIG. 3B or 3C. Or fallen.

  Still, when the grooves 14 are continuously formed in a letter C shape, communication with the RFID tag 500 is possible by radio waves emitted through any of the plurality of grooves 14 located in the vicinity of the RFID tag 500.

  The shape of each groove 14 is a rectangular shape here, but other conditions include the length and width of the RFID antenna cell 10, the dielectric constant of the insulator 13, and the formation surface of the groove 14 to the RFID tag. It is determined by the distance.

  Generally, the intensity of the radio wave output from the groove 14 increases as the aspect ratio of the groove 14 increases. Therefore, the aspect ratio of the groove 14 may be determined in consideration of the distance from the formation surface of the groove 14 to the RFID tag.

  As a result of the simulation, for example, when the length of the RFID antenna cell 10 is 200 mm to 210 mm, the width is 50 mm to 60 mm, and the angle of each groove 14 with respect to the axial direction of the RFID antenna cell 10 is in the range of 30 ° to 60 ° In other words, when the distance from the formation surface of the groove 14 to the RFID tag is about 6 cm, it has been found that if the length of the groove 14 is about 6 cm, the information from the RFID tag can be read reliably.

  As a result of the simulation, it was difficult to reliably read information from the RFID tag unless the aspect ratio between the length and width of the groove 14 was 100: 1 or less. Therefore, when the length of the groove 14 is about 6 cm, the width of the groove 14 is about 0.6 mm. On the other hand, it was also found that when the aspect ratio of the groove 14 is increased, the flying distance of the radio wave from the groove 14 increases, but the flying distance of the radio wave becomes uneven. From the viewpoint of radio wave flight distance and smoothing, the aspect ratio of each groove 14 is preferably 50: 1 or less, more preferably 20: 1 to 10: 1.

  The angle of each groove 14 with respect to the axial direction of the RFID antenna cell 10 is preferably about 45 °, but it has been found that information from the RFID tag can be reliably read when it is in the range of 30 ° to 60 °.

  This angle does not need to be the same for all the continuous grooves 14. For example, the angle of the C-shaped groove 14 at a certain position is set to 30 ° with respect to the axial direction of the array antenna. The angle of the groove 14 may be 45 ° with respect to the axial direction of the array antenna. The angle between the pair of C-shaped grooves 14 may not be the same.

  FIG. 4A is a schematic configuration diagram of the RFID tag system 100 according to the embodiment of the present invention. 4A shows the RFID antenna cell 10 described above, the progress management card rack 50 for stocking the transfer management card 400 in which the RFID antenna cell 10 is installed, and the information read by the RFID reader 30. FIG. The information processing apparatus 40 which processes is shown.

  FIG. 4B is a diagram showing the relationship between the progress management card rack 50 and the RFID antenna cell 10 shown in FIG. Here, a state in which three stages of progress management card racks 50 are connected and four RFID antenna cells 10 are connected is shown, but these numbers are merely examples.

  For example, the RFID antenna cells 10 may be connected in a number corresponding to the length of the progress management card rack 50. The RFID antenna cell 10 may be disposed on the back side of the surface where the card insertion slot of the progress management card rack 50 is provided. The RFID antenna cell 10 can be used by being housed in an antenna case (not shown).

  FIG. 4C is a schematic diagram of the progress management card rack 50 shown in FIG. The progress management card rack 50 is configured so that, for example, about 10 progress management cards 400 can be stocked per stage.

  However, since there are various sizes of the progress management card rack 50, even the progress management card rack 50 capable of stocking 10 progress management cards 400 is a progress in the progress management card rack 50. There are various cases of the vertical position of the management card 400.

  When the RFID antenna cell 10 in which the grooves 14 are continuously formed in a C-shape is used, the RFID card is affixed to the progress management card 400 regardless of the position of the progress management card 400 in the progress management card rack 50. Radio waves can be transmitted to and received from the existing RFID tag 500.

  An example of use of the RFID tag system 100 according to the present embodiment will be described. First, when an order is placed for a certain product, information such as the destination of the order is stored in the RFID tag 500. Next, the RFID tag 500 is affixed to the progress management card 400, and then the progress management card 400 is stocked in the progress management card rack 50.

  At this time, in the case of the RFID tag system 100 of the present embodiment, the RFID reader 30 emits a radio wave for reading information based on the current flowing through the coaxial cable 20 from the groove 14 and is stored in the RFID tag 500 by the radio wave. Information can be read.

  The information is output to the RFID reader 30 through the coaxial cable 20 and output to the information processing apparatus 40. Therefore, the information processing apparatus 40 stores the information on the progress management card 400 stocked in the progress management card rack 50 at any time. Management can be performed. In other words, the insertion / extraction of the progress management card 400 with respect to the progress management card rack 50 can also be managed.

  Here, when the reception sensitivity of the RFID antenna cell 10 is changed when the distance between the RFID tag 30 and the RFID antenna cell 10 is changed, the reception sensitivity is good between 0 cm and 6 cm, and exceeds about 7.25 cm. It was found that the sensitivity deteriorated relatively rapidly.

  Thereafter, when preparation for shipment of the product to be ordered is completed, the progress management card 400 corresponding to the shipping destination of the product is extracted from the progress management card rack 50, and as shown in FIG. It is inserted into a vinyl pocket 300 provided in the packed cardboard box 200.

  FIG. 5 is a view showing a state in which a plurality of cardboard boxes 200 in which the progress management cards 400 are inserted into the vinyl pocket 300 are carried on the belt conveyor 600. FIG. 5 shows a state where the RFID tag system 100 is installed in the vicinity of the belt conveyor 600.

  When the cardboard box 200 is conveyed by the belt conveyor 600, the RFID tag system 100 is stored in the RFID tag 500 attached to the progress management card 400 attached to the cardboard box 200 as described above. Read information. Thereby, the conveyance management of the product toward a desired delivery destination can be performed.

  Here, the RFID antenna cell 10 when the distance between the RFID tag 30 and the RFID antenna cell 10 is changed depending on whether the longitudinal direction of the RFID tag 30 and the groove 14 is parallel or orthogonal, respectively. When the reception sensitivity is simulated, the difference in sensitivity between the two is within 2 dB between 0 cm and about 1.3 cm. Thereafter, as the distance between the RFID tag 30 and the RFID antenna cell 10 increases, the sensitivity difference increases linearly. When it was 5 cm apart, it was about 5 dB.

  As described above, in the present specification, the example in which the rectangular grooves 14 are arranged in a square shape has been described. However, the grooves 14 may not be rectangular in a strict sense, and may have a stepped shape as illustrated in FIG. The shape may be rectangular when viewed macroscopically.

1 is a schematic configuration diagram of an RFID tag system 100 according to an embodiment of the present invention. It is a perspective view which shows the typical structure of the RFID antenna cell 10 of FIG. It is explanatory drawing of the reason for forming a pair of groove | channel 14 in a square shape. 1 is a schematic configuration diagram of an RFID tag system 100 according to an embodiment of the present invention. It is a figure which shows the state in which the several cardboard box 200 in which the card 400 for progress management was inserted in the vinyl pocket 300 is mounted on the belt conveyor 600, and is conveyed. It is a figure which shows the modification of the groove | channel 14 in the RFID antenna cell 10 of FIG.

DESCRIPTION OF SYMBOLS 10 RFID antenna cell 11 Inner conductor 12 Outer conductor 13 Insulator 14 Groove 20 Coaxial cable 21 Core conductor 22 Covered conductor 30 RFID reader 40 Information processor 50 Card rack 200 Cardboard box 300 Vinyl pocket 400 Progress management card 500 RFID tag 600 belt conveyor

Claims (4)

In an RFID antenna cell that reads information stored in an RFID tag,
A transmission line having an inner conductor extending inside the insulator and an outer conductor located on the surface of the insulator;
An RFID antenna cell in which a groove extending at a required angle with respect to the inner conductor is continuously formed in a C shape on the first surface of the outer conductor. The RFID antenna cell according to claim 1, wherein each groove is formed at an angle of 30 ° to 60 ° with respect to the inner conductor.   The RFID antenna cell according to claim 1, wherein each groove is linear or stepped. An RFID antenna cell according to claim 1;
An RFID system comprising: an information processing device that processes information received by the RFID antenna cell.

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