JP6079949B2 - RFID system and reader / writer device - Google Patents

Description

  The present invention relates to an RFID system that performs wireless communication between an RFID (Radio Frequency IDentifier) tag attached to a traveling body traveling on a predetermined route and a reader / writer device.

  An example of a technique for reading an RFID tag attached to an article traveling on a predetermined route is disclosed in Patent Document 1. According to Patent Document 1, a forklift passes through a gate in which a plurality of antennas for reader / writers are installed while carrying a package with an RFID tag. The reader / writer reads the ID information of the RFID tag attached to the package using a plurality of antennas.

JP 2014-131934 A

  However, when a plurality of antennas for a reader / writer are installed, it is necessary to prevent mutual interference between antennas, and the mechanism for preventing mutual interference is complicated. In particular, when an RFID tag is provided on each of a plurality of traveling bodies that respectively travel on a plurality of routes and a plurality of antennas are arranged on the plurality of routes, a mechanism for preventing mutual interference is further complicated.

  SUMMARY OF THE INVENTION Therefore, a main object of the present invention is to provide an RFID system capable of simply and reliably performing wireless communication between an RFID tag provided on a traveling body traveling on each of a plurality of routes and a reader / writer device. It is to be.

  Another object of the present invention is to provide a reader / writer device capable of simply and reliably performing wireless communication with an RFID tag provided on a traveling body traveling on each of a plurality of routes.

  A reader / writer device according to the present invention includes an RFID tag provided on a traveling body traveling on each of a plurality of routes extending at a predetermined distance, a main surface, and a winding axis in a normal direction of the main surface. And a reader / writer device that performs wireless communication with the RFID tag, and the loop antenna has a plurality of openings and is connected in series with each other. Including the coil conductor, the plurality of openings have substantially the same area, and the distance between the plurality of openings substantially coincides with the predetermined distance.

  Preferably, the plurality of routes are arranged in a plane, and the substrate is arranged so that the plurality of openings overlap with the plurality of routes in plan view.

  In one aspect, each of the plurality of openings has a major axis and a minor axis, and the substrate is disposed such that the major axis is along the extending direction of the plurality of routes.

  In another aspect, the substrate is disposed directly below the plurality of routes.

  In another aspect, each of the plurality of coil conductors is formed on one main surface of the substrate and has a first number of turns, and is formed on the other main surface of the substrate and has a first number of turns. A second partial coil conductor having a large second number of turns is included, and the substrate is disposed such that the other main surface faces a plurality of routes.

  In still another aspect, the reader / writer device further includes a processing circuit that is mounted on the substrate so as to be sandwiched between the plurality of coil conductors in a plan view and processes the RF signal.

  A reader / writer device according to the present invention includes a substrate on which a loop antenna for performing wireless communication with an RFID tag provided on a traveling body traveling on each of a plurality of routes extending at a predetermined distance is formed on a main surface. The loop antenna includes a plurality of coil conductors connected in series with each of a plurality of openings, the plurality of openings having substantially the same area, and the distance between the plurality of openings is It almost coincides with the predetermined distance.

  Since the loop antenna includes a plurality of coil conductors connected in series, the magnetic field strength of the loop antenna locally increases at each of the plurality of openings of the plurality of coil conductors. Here, the plurality of openings have substantially the same area, and the distance between the plurality of openings substantially coincides with the distance between the plurality of routes. Therefore, by arranging the substrate so that the plurality of openings overlap with the plurality of routes in plan view, wireless communication is easily and reliably performed between the RFID tag of the traveling body traveling on each route and the reader / writer device. be able to.

  The above object, other objects, features and advantages of the present invention will become more apparent from the following detailed description of embodiments with reference to the drawings.

It is a perspective view which shows the basic structure of the reader / writer apparatus applied to the RFID system of this invention. It is an illustration figure which shows the structure of the reader-writer apparatus applied to the RFID system of this Example. It is an illustration figure which shows the structure of the principal part of the reader / writer apparatus shown in FIG. It is a bottom view which shows the state which looked at the reader / writer apparatus shown in FIG. 2 from right below. FIG. 3 is a circuit diagram showing an equivalent circuit of the reader / writer device shown in FIG. 2. It is an illustration figure which shows an example of the use condition of the reader / writer apparatus shown in FIG. (A) is an illustrative view showing an example of the positional relationship between the reader / writer device and the rail shown in FIG. 2, and (B) is an illustrative view showing an example of the positional relationship between another reader / writer device and the rail. (A) is a perspective view which shows the state which looked at the traveling body (minicar) from diagonally upward, (B) is a bottom view which shows the state which looked at the traveling body from right under. It is an illustration figure which shows an example of the course for racing completed by assembling a rail and a reader / writer apparatus. It is an illustration figure which shows another example of the use condition of the reader / writer apparatus shown in FIG. It is an illustration figure which shows another example of the course for racing completed by assembling a rail and a reader / writer apparatus. (A) is a bottom view showing a state in which the reader / writer device of another embodiment is viewed from directly below, and (B) is a top view showing a state in which the reader / writer device of another embodiment is viewed from directly above. .

[Basic configuration]
FIG. 1 shows a basic configuration of a reader / writer device applied to the RFID system of the present invention. According to FIG. 1, the reader / writer device has a substrate 1 on which a loop antenna 2 and an RFIC (Radio Frequency Integrated Circuit) element 3 are formed on the main surface. The loop antenna 2 includes two coil conductors CIL1 and CIL2 connected in series with two openings OP1 and OP2, respectively. Here, the openings OP1 and OP2 have substantially the same area. In addition, the two routes RT1 and RT2 are arranged in a plane and extend in parallel, and the distance between the openings OP1 and OP2 substantially coincides with the distance between the two routes RT1 and RT2. The RFIC element 3 includes an RFIC chip having a reader / writer function, and the loop antenna 2 is connected to the RFIC element 3 to constitute a reader / writer antenna.

  The substrate 1 is arranged immediately below the routes RT1 and RT2 so that the openings OP1 and OP2 overlap with the routes RT1 and RT2, respectively, in plan view. A traveling body (not shown) is equipped with an RFID tag and travels on routes RT1 and RT2. When the traveling body passes over the coil conductor CIL1 or CIL2, wireless communication using the HF band as a carrier frequency is performed between the reader / writer device and the RFID tag.

Since the loop antenna 2 includes two coil conductors CIL1 and CIL2 connected in series, the magnetic field strength of the loop antenna 2 locally increases in each of the two openings OP1 and OP2. Here, the openings OP1 and OP2 have substantially the same area, and the distance between the openings OP1 and OP2 is substantially equal to the distance between the routes RT1 and RT2. Therefore, by arranging the substrate 1 so that the openings OP1 and OP2 overlap the routes RT1 and RT2 in plan view, it is simple and reliable between the RFID tag of the traveling body traveling on the route RT1 or RT2 and the reader / writer device. Wireless communication can be performed. The coil conductors CIL1 and CIL2 are connected so that the magnetic fields generated in the coil conductors are in phase so that the magnetic fields of the coil conductors are not easily coupled.
[Example]

  Referring to FIGS. 2 and 3, reader / writer device 10 of this embodiment is a device typically having a 13.56 MHz band as a communication frequency, and is a substrate made of epoxy resin as a material and having a rectangular main surface. 12 is included. The substrate 12 is a so-called printed wiring board and is a hard substrate, but may be a flexible substrate. In this embodiment, the X axis is assigned to the length direction of the substrate 12, the Y axis is assigned to the width direction of the substrate 12, and the Z axis is assigned to the thickness direction of the substrate 12.

  An RFIC element 14 having a reader / writer function and a PIC (Peripheral Interface Controller) element having a controller function are provided at the center of one main surface (specifically, the lower surface) of the substrate 12, that is, in a region between the coil conductors CIL1 and CIL2. 22 is implemented. More specifically, the RFIC element 14 is mounted at a slightly negative position in the Y-axis direction, and the PIC element 22 is mounted at a slightly positive position in the Y-axis direction. The PIC element 22 is connected to the RFIC element 14 by the wiring conductor 20, and is connected to the external wiring 26 (described later) by the wiring conductor 24. The wiring conductor 24 constitutes an interface terminal with an external circuit.

  The loop antenna 16 is formed by thin-film loop conductors 16a to 16d and a wiring conductor 16e and rod-shaped interlayer connection conductors 18a to 18b. Among these, the loop conductor 16a is disposed on the negative side region in the X-axis direction of one principal surface of the substrate 12, and the loop conductor 16b is disposed on the positive region in the X-axis direction on one principal surface of the substrate 12. The The loop conductor 16c is disposed in the negative side region in the X-axis direction of the other main surface (specifically, the upper surface) of the substrate 12, and the loop conductor 16d is on the positive side in the X-axis direction of the other main surface of the substrate 12. Arranged in the area. Further, the wiring conductor 16e is arranged so that the position on the negative side in the Y-axis direction on the other main surface of the substrate 12 extends in the X-axis direction. The interlayer connection conductor 18a is embedded in the substrate 12 in a posture extending along the Z-axis at a position on the negative side in the X-axis direction from the center of the main surface of the substrate 12. The interlayer connection conductor 18 b is embedded in the substrate 12 in a posture extending along the Z axis at a position on the positive side in the X axis direction from the center of the main surface of the substrate 12.

  One end of each of the loop conductors 16 a and 16 b is connected to the RFIC element 14. The other end of the loop conductor 16a is connected to one end of the loop conductor 16c via the interlayer connection conductor 18a, and the other end of the loop conductor 16b is connected to one end of the loop conductor 16d via the interlayer connection conductor 18b. . Further, the other ends of the loop conductors 16c and 16d are connected to each other by a wiring conductor 16e.

  Therefore, the loop conductors 16a and 16c and the interlayer connection conductor 18a form the coil conductor CIL11, and the loop conductors 16b and 16d and the interlayer connection conductor 18b form the coil conductor CIL12. The coil conductors CIL11 and CIL12 have openings OP11 and OP12 that face the Z-axis direction, respectively, and are connected in series.

  As can be seen from FIG. 4, the area of the opening OP1 substantially coincides with the area of the opening OP2, and the openings OP1 and OP2 both have a minor axis extending along the X axis and a major axis extending along the Y axis. That is, the outer edge shape of the coil conductors CIL11 and CIL12 has a shape having a major axis along the extending direction of the routes RT11 and RT12 in plan view. Further, routes RT11 and RT12 described later have a common width and extend in parallel on a plane, and the distance between the openings OP1 and OP2 substantially coincides with the distance between the two routes RT11 and RT12. . The magnetic field strength of the loop antenna 16 locally increases in each of the openings OP11 and OP12 thus formed. Further, since each coil conductor is composed of a laminated coil in which a plurality of loop conductors are stacked in the winding axis direction, the magnetic field strength in the winding axis direction can be increased.

  Since the RFIC element 14, the PIC element 22, and the coil conductors CIL11, CIL12 are in the positional relationship as described above, when the substrate 12 is viewed in plan, each of the RFIC element 14 and the PIC element 22 is the coil conductors CIL11 and CIL12. And further sandwiched by routes RT11 and RT12. As a result, the coupling amount of each coil conductor can be reduced, and the size of the main surface of the substrate 12 can be reduced.

  An equivalent circuit of the reader / writer device 10 having such a structure is shown in FIG. Inductors L1 and L2 correspond to coil conductors CIL11 and CIL12, respectively. The capacitor C1 corresponds to a chip capacitor (not shown) mounted on the substrate 12 together with the RFIC element 14. The inductor L1 and the inductor L2 are connected in series, and a capacitor C1 is connected in parallel to this to constitute an LC resonance circuit. One end of the inductor L1 is connected to one end of an RFIC chip 14c provided in the RFIC element 14. The other end of the inductor L1 is connected to one end of the inductor L2, and the other end of the inductor L2 is connected to the other end of the RFIC chip 14c. The frequency band of the communication signal is defined by a resonance circuit including the inductors L1 to L2, the capacitor C1, and the internal capacitance of the RFIC chip 14c.

  Referring to FIG. 6, reader / writer device 10 is arranged directly below rail 30 provided with lanes 301 and 302 and a separation wall 30 w that separates the lanes 301 and 302, and is connected to controller 28 via external wiring 26. . FIG. 6 shows a partial section of the rail 30, and the other main surface (upper surface) of the substrate 12 faces the lower surface of the illustrated rail 30. The route RT11 corresponds to the lane 301, and the route RT12 corresponds to the lane 302. The routes RT11 and RT12 have a common width and extend in parallel on a plane. As shown in FIG. 7A, the openings OP11 and OP12 overlap with the routes RT11 and RT12, respectively, in plan view, and the long axis of the opening OP11 and the long axis of the opening OP12 extend along the routes RT11 and RT12, respectively.

  FIG. 7B shows the positional relationship between another reader / writer device 10 ′ having a single coil conductor formed on the main surface of the substrate and the routes RT11 and RT12. As can be seen from a comparison with the reader / writer device 10 ', in the reader / writer device 10, the region where the magnetic field strength of the loop antenna 16 increases is matched to each of the routes RT11 and RT12, so that a null point is less likely to occur.

  The traveling body 40 traveling on the route RT11 or RT12 is configured as shown in FIGS. 8 (A) and 8 (B). The traveling body 40 is specifically a minicar, and the vehicle width is slightly smaller than the width of each of the routes RT11 and RT12. An RFID tag 42 is mounted in front of the lower surface of the traveling body 40. The RFID tag 42 includes a tag RFIC chip and a coiled loop conductor 44 connected to the RFIC chip. The coiled loop conductor 44 provided in the RFID tag 42 has a winding axis orthogonal to the lower surface of the traveling body 40.

  While the RFID tag 42 is mounted on the lower surface of the traveling body 40, the communication distance between the RFID tag 42 and the reader / writer device 10 is shortened by arranging the reader / writer device 10 directly below the rail 30. In this embodiment, an RFID system is constituted by the RFID tag 42 and the reader / writer device 10 thus provided. Note that the reader / writer device 10 may be embedded in the rail 30.

  The traveling body 40 travels on a race course assembled as shown in FIG. When the traveling body 40 passes immediately above the reader / writer device 10, wireless communication is performed between the reader / writer device 10 and the RFID tag 42. Identification information of the traveling body 40 is stored in the RFID tag 42, and this identification information is read by the reader / writer device 10. As described above, the long axis of the opening OP11 extends along the route RT11, and the long axis of the opening OP12 also extends along the route RT12. For this reason, the concern that reading of the identification information fails due to the speed of the traveling body 40 is reduced.

  The read identification information is given to the controller 28 via the external wiring 26. The controller 28 displays the circulation information such as the number of laps on the display panel 28a based on the given identification information. The display mode follows the operation of the operation buttons 28b, 28b,.

  As can be seen from the above description, the traveling body 40 on which the RFID tag 42 is mounted travels on each of the routes RT11 and RT12 extending at a predetermined distance. The reader / writer device 10 has a substrate 12 on which a loop antenna 16 is formed on the main surface, and performs wireless communication with the RFID tag 42. Loop antenna 16 includes coil conductors CIL11 and CIL12 connected in series with openings OP11 and OP12, respectively, and openings OP11 and OP12 have approximately the same area, and the distance between openings OP11 and OP12 is the root RT11 and It is almost the same as the distance between RT12.

  Since loop antenna 16 includes coil conductors CIL11 and CIL12 connected in series, the magnetic field strength of loop antenna 16 locally increases in each of openings OP11 and OP12 that coil conductors CIL11 and CIL12 have, respectively. Here, the openings OP11 and OP12 have substantially the same area, and the distance between the openings OP11 and OP12 substantially coincides with the distance between the routes RT11 and RT12.

  Therefore, by arranging the substrate 12 so that the openings OP11 and OP12 overlap with the routes RT11 and RT12, respectively, in plan view, the RFID tag 42 of the traveling body 40 traveling on the route RT11 or RT12 and the reader / writer device 10 are arranged. Wireless communication can be performed simply and reliably.

  In this embodiment, on the assumption that two routes RT11 and RT12 are formed on the rail 30, the single reader / writer device 10 is arranged directly below the rail 30 (see FIG. 6). However, when the rail 30 ′ in which the four routes RT 11 to RT 14 are formed is used instead of the rail 30, the two reader / writer devices 10 and 10 are arranged directly below the rail 30 ′ in the manner shown in FIG. Or it is necessary to arrange | position the single reader-writer apparatus (not shown) in which the four coil conductors were formed directly under rail 30 '.

  In this embodiment, the reader / writer device 10 is arranged directly below the rail 30 so that the openings OP1 and OP2 overlap the routes RT11 and RT12 in plan view (see FIG. 9). However, the reader / writer device 10 may be arranged directly below the rail 30 so that the intersection where the routes RT11 and RT12 intersect and the opening OP11 or OP12 overlap each other (see FIG. 11).

  Further, in this embodiment, the number of turns of each of the coil conductors CIL11 and CIL12 is set to one time on the one main surface side of the substrate 12 and once on the other main surface side of the substrate 12 (FIG. 2 or FIG. 3). However, considering that the other main surface of the substrate 12 faces the lower surface of the rail 30, the number of turns on the other main surface side of the substrate 12 may be made larger than the number of turns on the one main surface side of the substrate 12. Good. In this case, the coil conductors CIL11 and CIL12 connected in series by forming the loop antenna 16 are formed, for example, as shown in FIGS. 12 (A) and 12 (B).

  12A and 12B, loop conductors 16c ′ and 16d ′ and a wiring conductor 16e ′ are formed on the other main surface of the substrate 12 instead of the loop conductors 16c and 16d and the wiring conductor 16e. . Of these, the coil conductor CIL11 is formed by the loop conductors 16a and 16c ′ and the interlayer connection conductor 18a, and the coil conductor CIL12 is formed by the loop conductors 16b and 16d ′ and the interlayer connection conductor 18b.

  The coil conductor CIL11 includes a partial coil conductor CIL11a having one turn and a partial coil conductor CIL11b having two turns. The coil conductor CIL12 has two turns and the partial coil conductor CIL12a having one turn. Partial coil conductor CIL12b. Partial coil conductors CIL11a and CIL12a are formed on one main surface of substrate 12, and partial coil conductors CIL11b and CIL12b are formed on the other main surface of substrate 12.

  By adopting such an antenna structure, the magnetic field strength on the other main surface side of the substrate 12 becomes stronger than the magnetic field strength on the one main surface side of the substrate 12, and the other main surface side of the substrate 12 is on the traveling lane side. As a result, the accuracy of reading the identification information from the RFID tag 42 provided on the traveling body 40 is improved.

  In the above-described embodiments, the HF band RFID system using the HF band frequency band has been described. However, an RFID system using another frequency band such as the UHF band may be used.

DESCRIPTION OF SYMBOLS 10 ... Reader / writer apparatus 12 ... Board | substrate 14 ... RFIC element (processing circuit)
16 ... Loop antenna 22 ... PIC element (processing circuit)
OP1 to OP2, OP11 to OP12 ... opening CIL1 to CIL2, CIL11 to CIL12 ... coil conductor RT1 to RT2, RT11 to RT14 ... route 40 ... traveling body 42 ... RFID tag

Claims (7)

An RFID tag provided on a traveling body traveling on each of a plurality of routes extending at a predetermined distance;
A reader / writer device that includes a substrate having a main surface and a loop antenna having a winding axis in a direction normal to the main surface and performs wireless communication with the RFID tag;
An RFID system comprising:
The loop antenna includes a plurality of coil conductors each having a plurality of openings and connected in series,
The plurality of openings have substantially the same area;
The RFID system, wherein a distance between the plurality of openings substantially matches the predetermined distance. The plurality of routes are arranged in a plane,
The RFID system according to claim 1, wherein the substrate is arranged such that the plurality of openings overlap with the plurality of routes in plan view. Each of the plurality of openings has a major axis and a minor axis;
The RFID system according to claim 2, wherein the substrate is arranged such that the long axis is along an extending direction of the plurality of routes.   The RFID system according to claim 2, wherein the substrate is arranged immediately below the plurality of routes. Each of the plurality of coil conductors is formed on one main surface of the substrate and has a first number of turns, and is formed on the other main surface of the substrate and is larger than the first number of turns. Including a second partial coil conductor having a second number of turns;
5. The RFID system according to claim 2, wherein the substrate is disposed such that the other main surface faces the plurality of routes. 6.   6. The RFID system according to claim 2, wherein the reader / writer device further includes a processing circuit that is mounted on the substrate so as to be sandwiched between the plurality of coil conductors in a plan view and processes an RF signal. A reader / writer device having a substrate on which a loop antenna for performing wireless communication with an RFID tag provided on a traveling body traveling on each of a plurality of routes extending at a predetermined distance is formed on a main surface,
The loop antenna includes a plurality of coil conductors each having a plurality of openings and connected in series,
The plurality of openings have substantially the same area;
A reader / writer device, wherein a distance between the plurality of openings substantially coincides with the predetermined distance.

Images