KR20070119676A - Rfid tag - Google Patents

Abstract

In a RFID tag (11), antenna wires (14a, 14b) are embedded in a thin plate (12) made of a resin. The antenna wires (14a, 14b) configure, for example, a dipole antenna. In the thin plate (12), a radio wave reflecting material (15a, 15b, 15c, 15d) which is made of a metal and extends parallel to the antenna wires (14a, 14b) is further embedded. Radio waves entering toward the thin plate (12) are reflected by the radio wave reflecting material (15a, 15b, 15c, 15d). The reflected radio waves are guided to the antenna wires (14a, 14b). A reception quantity of the radio waves increases at the antenna wires (14a, 14b). The RFID tag remarkably contributes to increase of a communication distance. Since the radio wave reflecting material (15a, 15b, 15c, 15d) is embedded in the thin plate (12), the conventional application can be ensured. When a reflecting plate is attached to the external side of the RFID tag, the application of the RFID tag is greatly limited.

Description

RFID tag {RFID TAG}

The present invention relates to an RFID tag.

RFID tags are well known. In general, RFID tags include dipole antennas or patch antennas. The dipole antenna or patch antenna includes an antenna element corresponding to the length specified by λ / 2. Based on such an antenna element, the RFID tag can transmit and receive a required radio signal.

When the transmission power of the radio signal is enhanced, the RFID tag can sufficiently establish radio communication even if the RFID tag is far from the source of the radio signal (commonly referred to as a reader / writer). However, the maximum of the transmission power is regulated, for example, by law. Thus, as disclosed, for example, in US Pat. No. 4,644,740, a method of extending the communication distance from the source to the RFID tag without enhancing the transmission power of the wireless signal is sought.

Patent Document 1: US Patent No. 6,441,740

Patent Document 2: US Patent No. 6,535,175

The present invention has been made in view of the above circumstances, and an object thereof is to provide an RFID tag which can extend a communication distance without enhancing the transmission power of a radio signal.

In order to achieve the above object, according to the present invention, an RFID tag comprising a thin resin plate, an antenna element embedded in the thin plate, and a metal radio wave reflector embedded in the thin plate and extending in parallel to the antenna element Is provided.

According to such an RFID tag, radio waves entering the thin plate are reflected by the radio wave reflector. The reflected radio waves can be directed towards the antenna element. The radio wave reflector increases the amount of radio waves received by the antenna element. RFID tags greatly contribute to the increase in communication distance. In addition, since the radio wave reflecting material is embedded in the thin plate, it can be used for the same purposes as before. If a reflecting plate is added outside the RFID tag, the use of the RFID tag is significantly limited.

The antenna element may comprise a dipole antenna or a folded dipole antenna. The antenna is composed of antenna elements corresponding to the length specified by λ / 2. Based on such an antenna element, the RFID tag can transmit and receive a required radio signal.

The radio wave reflectors may be disposed apart from each other, and may be composed of a plurality of elongate members that form flat surfaces that are inclined at an arbitrary inclination angle around an axis parallel to the antenna element. Reflection of radio waves can be realized by the flat surface in such an elongate member. By the action of the flat surface, radio waves can be directed toward the antenna element.

At this time, the plurality of elongate members are disposed along the surface of the thin plate, and are arranged along the rear surface of the thin plate, the first group of elongate members having the outer end far from the antenna element toward the rear surface of the thin plate. A second elongate member group may be included in which a distant outer end is brought closer toward the surface of the sheet. According to this RFID tag, radio waves entering the surface of the thin plate are reflected on the flat surface of the second elongate member group. The reflected radio waves are directed towards the antenna element. Similarly, radio waves entering the rear surface of the thin plate are reflected on the flat surface of the first elongate member group. The reflected radio waves are directed towards the antenna element. The radio wave reflector can increase the reception amount of radio waves incident from the two directions by the antenna element.

Instead of this configuration, the plurality of elongate members may be disposed along the back surface of the thin plate, and may include an elongated group of members in which an outer end far from the antenna element is brought toward the surface of the thin plate. In such an RFID tag, a shield plate made of, for example, a metal may be adhered to the rear surface of the thin plate. According to such an RFID tag, it is always possible to concentrate the radio waves on the antenna element satisfactorily regardless of the kind of material contacting the back surface of the thin plate.

The radio wave reflectors may be composed of a plurality of elongate members which are disposed apart from each other and form a semi-cylindrical surface composed of a generatrix parallel to the antenna element. In such an elongate member, reflection of radio waves by the semi-cylindrical surface can be realized. By the action of the semi-cylindrical surface, radio waves can be directed toward the antenna element.

At this time, the plurality of elongate members are disposed along the surface of the thin plate, and are arranged along the back surface of the thin plate, and the first elongate member group is disposed along the back surface of the thin plate. And a second elongate member group facing each other. According to this RFID tag, radio waves entering the surface of the thin plate are reflected at the semi-cylindrical surface of the second elongate member group. The reflected radio waves are directed towards the antenna element. Similarly, radio waves entering the rear surface of the thin plate are reflected at the semi-cylindrical surface of the first elongate member group. The reflected radio waves are directed towards the antenna element. The radio wave reflector can increase the reception amount of radio waves incident from two directions by the antenna element.

Instead of this configuration, the plurality of elongate members may be disposed along the surface of the thin plate, and may include an elongated member group in which a semi-cylindrical surface is opposed to the rear surface of the thin plate. In such an RFID tag, a shield plate made of, for example, a metal may be adhered to the surface of the thin plate. According to such an RFID tag, it is always possible to concentrate the radio waves on the antenna element satisfactorily regardless of the kind of material contacting the back surface of the thin plate.

In addition, the radio wave reflector may be constituted by a plurality of elongate members which are disposed apart from each other and form a cylindrical surface composed of a bus bar parallel to the antenna element. The radio wave reflector may be composed of a plurality of elongate members that form a plurality of hemispheres arranged in parallel to the antenna element.

1 is a schematic plan view of an RFID tag according to a first embodiment of the present invention.

FIG. 2 is a partially enlarged cross-sectional view of the RFID tag along line 2-2 of FIG. 1; FIG.

3 is an enlarged cross-sectional view of an RFID tag along line 3-3 of FIG. 1;

4 is a plan view of a metal thin film schematically showing a manufacturing process of an RFID tag.

5 is an enlarged cross-sectional view of the RFID tag corresponding to FIG. 3 and according to a modification of the first embodiment;

6 is an enlarged cross-sectional view of an RFID tag corresponding to FIG. 3 and according to another modification of the first embodiment;

7 is a partially enlarged perspective view schematically showing a hemisphere formed of an elongate member.

8 is an enlarged cross-sectional view of the RFID tag according to another modification of the first embodiment, corresponding to FIG. 3.

9 is an enlarged cross-sectional view of the RFID tag corresponding to FIG. 3 and according to the second embodiment of the present invention;

10 is an enlarged cross-sectional view of an RFID tag according to a modification of the second embodiment, corresponding to FIG. 3.

11 is an enlarged cross-sectional view of an RFID tag corresponding to FIG. 3 and according to another modification of the second embodiment;

12 is an enlarged cross-sectional view of the RFID tag corresponding to FIG. 3 and according to the third embodiment of the present invention;

FIG. 13 corresponds to FIG. 3 and is an enlarged cross-sectional view of an RFID tag according to a modification of the third embodiment; FIG.

FIG. 14 is an enlarged cross-sectional view of an RFID tag corresponding to FIG. 3 and according to another modification of the third embodiment; FIG.

15 is an enlarged cross-sectional view of an RFID tag according to another modification of the third embodiment, corresponding to FIG. 3;

Fig. 16 is a perspective view of a radio wave reflector according to a fourth embodiment of the present invention.

17 is a perspective view of a radio wave reflector according to a modification of the fourth embodiment.

18 is a perspective view of a radio wave reflector according to another modification of the fourth embodiment.

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of this invention is described with reference to an accompanying drawing.

1 shows an RFID tag 11 according to a first embodiment of the present invention. This RFID tag 11 has a thin plate 12 made of resin. The semiconductor chip 13 is embedded in the thin plate 12. The semiconductor chip 13 includes, for example, a wireless transmission / reception circuit, a logic circuit, and a memory. For example, predetermined information is stored in the memory.

Similarly, the thin plate 12 is embedded with the antenna device 14. This antenna device 14 includes a pair of antenna elements 14a and 14b constituting a so-called dipole antenna. The antenna device 14 is connected to the semiconductor chip 13. Power is generated in the semiconductor chip 13 in accordance with the radio wave received by the antenna device 14. Based on this electric power, the semiconductor chip 13 performs a predetermined operation. For example, information in the memory can be sent from the antenna device 14.

Similarly, the radio wave reflecting material 15 is embedded in the thin plate 12. This radio wave reflector 15 is made of metal such as iron, aluminum, or copper. The radio wave reflector 15 is composed of a plurality of elongate members 15a, 15b, 15c, and 15d extending in parallel to the antenna elements 14a and 14b. The elongate members 15a to 15d are arranged apart from each other, for example. Details of the elongate members 15a to 15d will be described later.

As shown in FIG. 2, the thin plate 12 includes a substrate 16 composed of a resin material such as polyester or polyimide, for example. The semiconductor chip 13 described above is disposed in the window hole of the substrate 16. The semiconductor chip 13 is formed with a pair of conductive contacts 17. One end of each of the antenna elements 14a and 14b is supported by the respective conductive contacts 17. One end of the antenna elements 14a, 14b is joined to the conductive contact 17 by, for example, a bump 18. In this way, the antenna elements 14a and 14b and the semiconductor chip 13 are electrically connected.

The semiconductor chip 13 is covered with a sealing material 19 on the substrate 16. The sealing material 19 should just be comprised from a resin material, for example. The substrate 16 is interposed between the pair of thin film materials 21 and 21. The thin film material 21 is comprised from the adhesive material 22 of the inner side, and the coating material 23 of the outer side. The adhesive 22 may be made of, for example, ethyl vinyl acetate, butyral resin, or silicone resin adhesive. The coating | covering material 23 should just be comprised from high strength polymer materials, such as polyester, a polyimide, and polyethylene, for example. For example, as is apparent from FIG. 1, when the thin film materials 21 are bonded to each other, the semiconductor chip 13, the antenna device 14, and the radio wave reflecting material 15 are interposed between the thin film materials 21. In this way, the semiconductor chip 13, the antenna device 14, and the radio wave reflecting material 15 are embedded in the thin plate 12.

3 shows a radio wave reflector 15 according to the first embodiment of the present invention. The individual elongate members 15a, 15b, 15c, 15d form a flat surface 24 that is inclined at an arbitrary inclination angle α around an axis parallel to the antenna elements 14a, 14b. Based on this inclination angle α, the flat surface 24 brings the outer end far from the antenna elements 14a and 14b toward the surface of the thin plate 12. The flat surface 24 extends over the entire length of the elongate members 15a-15d. Each elongate member 15a, 15b, 15c, 15d may have a uniform cross section in the longitudinal direction. The inclination angle α of the flat surface 24 may be determined based on the expected incidence direction of the radio wave 25 and the relative positions of the elongate members 15a-15d and the antenna elements 14a, 14b. According to this RFID tag 11, as is apparent from FIG. 3, radio waves 25 entering the surface of the thin plate 12 are reflected on the flat surface 24. The reflected radio waves are directed toward the antenna elements 14a and 14b. The radio wave reflector 15 increases the reception amount of radio waves by the antenna elements 14a and 14b. The RFID tag 11 contributes greatly to the increase of the communication distance.

Next, the manufacturing method of the RFID tag 11 is demonstrated briefly. Here, for example, as shown in FIG. 4, an elongated metal sheet 27 is prepared. In this metal thin plate 27, a pair of support members 27a and 27a extend in the longitudinal direction. The distance W between the supporting members 27a is set larger than the overall length of the elongate members 15a and 15b. Between the supporting members 27a and 27a, a plurality of rows of thin plate members 27b, 27c, ... are arranged in the longitudinal direction of the metal thin plate. This arrangement of thin plate members 27b, 27c, ... reflects the arrangement of the elongate members 15a-15d in the RFID tag 11. The supporting member 27a is bent based on the inclination angle α of the corresponding elongate members 15a to 15d between the thin plate members 27b, 27c,...

For example, the metal thin plate 27 is used for molding the thin plate 12. The bent metal sheet 27 is installed in a cavity of a mold (not shown). When injection molding is performed, the metal thin plate 27 is wrapped in a resin material in the cavity. After cooling, the molded resin plate is taken out of the mold. The thin plate 12 is cut out from such a resin plate. The thin plate 12 may include prescribed thin plate members 27b, 27c,... The RFID tag 11 described above may be manufactured based on the thin plate 12. However, the RFID tag 11 may be manufactured based on another method.

In such an RFID tag 11, for example, as shown in FIG. 5, instead of the flat surface 24, the semi-cylindrical surface 28 may be formed in the individual elongate members 15a, 15b, 15c, and 15d. This semi-cylindrical surface 28 is composed of bus bars parallel to the antenna elements 14a and 14b. The semi-cylindrical surface 28 should just extend over the full length of the elongate member 15a-15d. Each elongate member 15a, 15b, 15c, 15d may have a uniform cross section.

Here, the semi-cylindrical surface 28 opposes one plane including the surface of the thin plate 12. Thus, radio waves 25 entering the surface of the thin plate 12 are reflected at the semi-cylindrical surface 28. The reflected radio waves are directed toward the antenna elements 14a and 14b. The radio wave reflector 15 increases the reception amount of radio waves by the antenna elements 14a and 14b. The RFID tag 11 contributes greatly to the increase of the communication distance. In addition, the cross-sectional shape of the semi-cylindrical surface 28 may not only be defined based on a circle, but may be defined based on an ellipse, for example.

In addition, in such an RFID tag 11, for example, as shown in FIG. 6, instead of the flat surface 24 or the semi-cylindrical surface 28, the cylindrical surface is formed on the individual elongated members 15a, 15b, 15c, and 15d. (29) may be formed. This cylindrical surface 29 is comprised by the bus bar parallel to the antenna elements 14a and 14b. The cylindrical surface 29 may just extend over the full length of the elongate member 15a-15d. Each elongate member 15a, 15b, 15c, 15d may have a uniform cross section. According to the RFID tag 11, the same effect as the above-described RFID tag 11 can be obtained. In addition, the cross-sectional shape of the cylindrical surface 29 may not only be defined based on a circle, but may be defined based on an ellipse, for example.

In addition, in such an RFID tag 11, as shown in FIG. 7, for example, a plurality of hemispherical surfaces 31 may be formed on the elongate members 15a to 15d. The hemispherical surface 31 may just be arranged over the full length of the elongate member 15a-15d. According to such an RFID tag 11, the same effect as the above-described RFID tag 11 can be obtained, for example, as is apparent from FIG.

9 schematically shows a radio wave reflector 15 according to a second embodiment of the present invention. In this second embodiment, the radio wave reflecting member 15 is the first elongate member group 32 disposed along the surface of the thin plate 12 and the second elongate member group disposed along the back surface of the thin plate 12. 33 is provided. The individual elongate members 32a, 32b, 32c, 32d, 33a, 33b, 33c, and 33d included in the first elongate member group 32 and the second elongate member group 33 are the elongated members described above. What is necessary is just to be comprised similarly to (15a-15d). Here, for example, in the first elongate member group 32, the outer end far from the antenna elements 14a and 14b to the individual elongate members 32a, 32b, 32c, and 32d is proximate toward the rear surface of the thin plate 12. Flat surface 24 is formed. On the other hand, in the second elongate member group 33, the external ends far from the antenna elements 14a and 14b are brought closer to the surfaces of the thin plates 12 to the individual elongate members 33a, 33b, 33c, and 33d. The flat surface 24 is formed. According to this RFID tag 11, radio waves 25 entering the surface of the thin plate 12 are reflected on the flat surface 24 of the second elongate members 33a to 33d. The reflected radio waves are directed toward the antenna elements 14a and 14b. Similarly, the radio wave 34 entering the rear surface of the thin plate 12 is reflected on the flat surface 24 of the first elongate members 32a to 32d. The reflected radio waves are directed toward the antenna elements 14a and 14b. The radio wave reflector 15 can increase the reception amount of radio waves incident from the two directions by the antenna elements 14a and 14b.

In addition, in such an RFID tag 11, for example, as shown in Figs. 10 and 11, the individual elongate members 32a, 32b, 32c, 32d, 33a, like the elongated members 15a to 15d described above, Instead of the flat surface 24, the semi-cylindrical surface 26 and the semi-circular spherical surface 31 may be formed in 33b, 33c, 33d. In this case, in the first elongate member group 32, the semi-cylindrical surface 26 and the semi-circular spherical surface 31 may be opposed to one flat surface including the back surface of the thin plate 12. On the other hand, in the second elongate member group 33, the semi-cylindrical surface 26 and the hemispherical surface 31 may be opposed to one flat surface including the surface of the thin plate 12.

12 shows the radio wave reflecting material 15 according to the third embodiment of the present invention. In this third embodiment, the radio wave reflecting member 15 includes an elongate member group 35 disposed along the rear surface of the thin plate 12. A metal shield plate 36 is bonded to the back surface of the thin plate 12. The individual elongate members 35a, 35b, 35c, and 35d of the elongate member group 35 may be configured similarly to the elongate members 15a to 15d described above. Here, the flat surfaces 24 are formed in the individual elongated members 35a, 35b, 35c, and 35d so as to bring the outer end far from the antenna elements 14a and 14b toward the surface of the thin plate 12. According to the RFID tag 11, since the shield plate 36 is adhered to the rear surface of the thin plate 12, the antenna elements 14a and 14b are always satisfactory regardless of the kind of material contacting the rear surface of the thin plate 12. ) Can concentrate radio waves. In addition, in the individual elongate members 35a, 35b, 35c, and 35d, a semi-cylindrical surface 28 may be formed as shown in FIG. 13 instead of the flat surface 24 as described above, and in FIG. Cylindrical surface 29 may be formed as shown, and hemispherical surface 31 may be formed as shown in FIG.

Fig. 16 shows a radio wave reflector 15 according to a fourth embodiment of the present invention. In this fourth embodiment, the radio wave reflector 15 includes a reflecting plate 41 that surrounds the virtual semi-cylindrical surface outside the RFID tag 11. The antenna elements 14a and 14b of the RFID tag 11 are disposed along the axis of the virtual semi-cylindrical surface. Corresponding to this arrangement, the RFID tag 11 is fixed to the support member 42. The supporting member 42 is fixed to the reflecting plate 41.

Inside the reflecting plate 41, a plurality of elongate members 43 extending in parallel with the axis of the semi-cylindrical surface are fixed. The elongate member 43 forms the semicylindrical surface 44 comprised from the bus bar parallel to the axis line of the semicylindrical surface. The semi-cylindrical surface 44 may be extended over the entire length of the elongate member 43. Each elongate member 43 may have a uniform cross section.

According to this reflecting plate 41, radio waves are concentrated on the antenna elements 14a and 14b. Therefore, the amount of reception of radio waves is increased in the antenna elements 14a and 14b. Further, even when radio waves enter from either direction due to the action of the semi-cylindrical surface 44, the radio waves can be reliably concentrated on the antenna elements 14a and 14b. This reflector 41 greatly contributes to the increase in the communication distance. In addition, in such a reflecting plate 41, the arrangement of the hemispherical surfaces 31, 31, ... may be used instead of the elongate member 43.

In such a radio wave reflector 15, instead of the reflecting plate 41 surrounding the virtual semi-cylindrical surface, a reflecting plate 45 composed of two flat plates may be used, for example, as shown in FIG. In this case, as described above, the semi-cylindrical surfaces 44, 44,... May be disposed parallel to the antenna elements 14a, 14b. Instead of the semi-cylindrical surface 44, however, the arrangement of the semi-cylindrical surfaces 31, 31, ... may be used as described above. In addition, for example, as shown in Fig. 18, in the radio wave reflector 15, a reflecting plate 46 surrounding the hemisphere may be used. In this case, the hemispherical surfaces 31, 31,... Can be filled inside the reflecting plate 46.

Claims (10)

An RFID tag comprising a resin thin plate, an antenna element embedded in the thin plate, and a metal radio wave reflector embedded in the thin plate and extending in parallel to the antenna element. The RFID tag of claim 1, wherein the antenna element constitutes a dipole antenna or a folded dipole antenna. 2. The radio wave reflector according to claim 1, wherein the radio wave reflectors are formed of a plurality of elongate members disposed apart from each other and forming a flat surface inclined at an arbitrary inclination angle around an axis parallel to the antenna element. RFID tag. The first plurality of elongated member groups according to claim 3, wherein the plurality of elongate members are disposed along the surface of the thin plate and have an outer end far from the antenna element proximate to the rear surface of the thin plate. And a second elongate member group disposed along the rear surface of the thin plate and having an outer end far from the antenna element toward the surface of the thin plate. 4. The RFID tag according to claim 3, wherein the plurality of elongate members includes an elongated group of members disposed along the rear surface of the thin plate and having an outer end far from the antenna element toward the surface of the thin plate. The RFID tag according to claim 1, wherein the radio wave reflectors are composed of a plurality of elongate members which are disposed apart from each other and form a semi-cylindrical surface composed of a bus bar parallel to the antenna element. The thin film member according to claim 6, wherein the plurality of elongate members are disposed along the surface of the thin plate, and are arranged along the back surface of the thin plate, the first group of elongate members arranged so as to oppose the semi-cylindrical surface to the rear surface of the thin plate. RFID tag, characterized in that it includes a second elongate member group facing the semi-cylindrical surface. 7. The RFID tag according to claim 6, wherein the plurality of elongate members includes an elongate member group disposed along the surface of the thin plate and opposing a semi-cylindrical surface to the rear surface of the thin plate. The RFID tag according to claim 1, wherein the radio wave reflectors are disposed apart from each other, and are formed of a plurality of elongate members that form a cylindrical surface composed of a bus bar parallel to the antenna element.  The RFID tag according to claim 1, wherein the radio wave reflector is composed of a plurality of elongate members forming a plurality of hemispherical surfaces arranged parallel to the antenna element.

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