JP5489978B2 - RFID reader / writer antenna - Google Patents

Description

  The present invention relates to an RFID reader / writer antenna, and more particularly to an RFID reader / writer antenna that can handle two or more frequency bands.

  Information management and settlement using an RFID (Radio Frequency IDentification) system have been performed recently. In such an RFID system, three frequency bands of 13.56 MHz band, UHF (950 MHz) band, and 2.45 GHz band are mainly used.

  In addition, an RFID reader / writer for reading and writing information to and from an RFID tag is connected to the antenna module substrate of the RFID reader / writer and the RFID antenna unit by a coaxial cable as disclosed in Patent Document 1, for example. Is.

  An example of an RFID antenna that can handle a plurality of frequency bands is disclosed in Patent Document 2, for example. The one disclosed in Patent Document 2 is an antenna used for an RFID tag, and can be used in a frequency band corresponding to each linear portion using a conductor configured as a loop antenna as a plurality of linear portions. is there.

  As another example of the RFID antenna for multiple frequency bands, for example, one disclosed in Patent Document 3 can be cited. In Patent Document 3, a plurality of antenna portions that resonate in different frequency bands are formed on the same plane so as to be connectable to an IC chip configured to be able to write and read information. .

JP 2008-278206 A Japanese Patent Laid-Open No. 2005-64865 JP 2005-252853 A

  However, in the case where the antenna module substrate and the antenna portion are connected by a coaxial cable as described in Patent Document 1, the characteristics of the antenna change depending on the difficulty of routing the coaxial cable or depending on the performance of the coaxial terminal. There was a case. Further, in the RFID antenna that can handle a plurality of frequency bands as described in Patent Document 2 and Patent Document 3, the size of the antenna portion can be increased. In addition, when the antenna unit is applied to an RFID reader / writer, the signal line routing between the antenna module substrate and the antenna unit may become a problem.

  In view of such circumstances, the present invention intends to provide a small and thin antenna for a RFID reader / writer that can cope with two or more frequency bands.

  In order to achieve the above-described object of the present invention, an RFID reader / writer antenna corresponding to two or more frequency bands according to the present invention is arranged on an antenna substrate, the antenna substrate, a hot-side connection portion, and a ground-side connection. Line corresponding to a perpendicular line passing through the center of the line connecting the hot side connection part and the ground side connection part in the plane of the antenna substrate, corresponding to the first frequency band extending from the common connection port. The center of the line connecting the hot side connection portion and the ground side connection portion in the antenna substrate plane corresponds to the first antenna consisting of the dipole antennas arranged symmetrically and the second frequency band extending from the common connection port. A second antenna composed of a dipole antenna arranged symmetrically with respect to a normal passing therethrough, a common connection port, a first antenna and a second antenna Circuit for driving the burner is one that includes a flexible cable for connecting the antenna module substrate to be mounted.

  Further, the first antenna and the second antenna may be a common dipole antenna.

  Furthermore, from the loop antenna corresponding to the 3rd frequency band which is arrange | positioned on an antenna board | substrate and has a 2nd hot side connection part and a 2nd ground side connection part and extended from a 2nd connection port A third antenna, a second connection port, and a second flexible cable for connecting the antenna module substrate on which a circuit for driving the third antenna is mounted may be provided.

  The third antenna may be a substantially quadrangular loop antenna, and a part thereof may include a chamfering portion for isolation with respect to the first antenna and / or the second antenna.

  The antenna substrate may be stacked on an antenna module substrate on which a circuit for driving the first antenna and the second antenna is placed.

  Furthermore, the RFID reader / writer antenna corresponding to two or more frequency bands of the present invention is provided on an antenna module substrate on which a flexible substrate and a circuit for driving the antenna are placed. A first antenna that is connected to a connection port having a hot-side connection portion and a ground-side connection portion and that is a loop antenna corresponding to the first frequency band, and a circuit that is disposed on the flexible substrate and drives the antenna are mounted. It is connected to a common connection port having a hot-side connection portion provided on the antenna module substrate to be placed, and corresponds to the second frequency band and the third frequency band, and consists of a modified monopole antenna that branches in the middle Each tip of the second antenna that branches off in the middle of the second antenna is on the side far from the first antenna. Placed the, a second antenna may be one having a.

  The second antenna may be disposed on the side of the first antenna so as not to surround the first antenna.

  In addition, the second antenna is configured such that one end portion branched in the middle is arranged between the line of the first antenna connected to the connection port and the line of the second antenna connected to the common connection port. It should be done.

  The antenna for the RFID reader / writer according to the present invention has an advantage that it is compatible with two or more frequency bands and is small and thin.

FIG. 1 is a schematic perspective view for explaining an RFID reader / writer antenna according to a first embodiment of the present invention. FIG. 2 is a schematic plan view for explaining the RFID reader / writer antenna according to the first embodiment of the present invention. FIG. 3 is a schematic plan view for explaining an RFID reader / writer antenna according to a second embodiment of the present invention. FIG. 4 is a schematic perspective view for explaining an RFID reader / writer antenna according to a third embodiment of the present invention. FIG. 5 is a schematic plan view for explaining an RFID reader / writer antenna according to a fourth embodiment of the present invention. FIG. 6 is a schematic plan view for explaining an RFID reader / writer antenna according to a fifth embodiment of the present invention.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described together with illustrated examples. FIG. 1 is a schematic perspective view for explaining an RFID reader / writer antenna according to a first embodiment of the present invention. FIG. 2 is a schematic plan view for explaining the RFID reader / writer antenna according to the first embodiment of the present invention. As shown in the figure, the RFID reader / writer antenna according to the first embodiment of the present invention mainly includes an antenna substrate 10, a common connection port 20, a first antenna 30, a second antenna 40, and a flexible cable 50. It is configured. In the illustrated example, an example of an RFID reader / writer antenna capable of transmitting and receiving data using two frequency bands is shown.

  The antenna substrate 10 serves as a base material for the antenna portion, and for example, a general printed circuit board is sufficient.

  The common connection port 20 is disposed on the antenna substrate 10 and has a hot-side connection portion 21 and a ground-side connection portion 22. A first antenna 30 and a second antenna 40 extend from the common connection port 20. An antenna module substrate 60 on which an antenna driving circuit provided outside the antenna substrate 10 is placed is connected to the common connection port 20 via a flexible cable 50. That is, the first antenna 30 and the second antenna 40 are configured to be a common input / output unit by the common connection port 20. In the illustrated example, the impedance matching pattern 25 is disposed in the vicinity of the common connection port 20, but the present invention is not limited to this pattern.

  The first antenna 30 extending from the common connection port 20 corresponds to the first frequency band. The first antenna 30 is a dipole antenna that is arranged in line symmetry with respect to a perpendicular passing through the center of the line connecting the hot side connection portion 21 and the ground side connection portion 22 in the plane of the antenna substrate 10. In the illustrated example, the first antenna 30 made of a dipole antenna is shown as an example in which the tip of the element shape of the dipole is configured in a meander shape. Since the area occupied by the antenna element can be reduced as a whole by being configured in a meander shape, the antenna substrate 10 can be downsized. However, the present invention is not limited to this, and the first antenna may be arranged such that the element shape of the dipole is symmetrical with the L shape or the C shape. In the illustrated example, the first antenna 30 is configured as an antenna of a 950 MHz band.

  Similarly to the first antenna 30, the second antenna 40 extending from the common connection port 20 corresponds to the second frequency band. The second antenna 40 is a dipole antenna that is placed in the plane of the antenna substrate 10 and is symmetrical with respect to a perpendicular that passes through the center of the line connecting the hot-side connection portion 21 and the ground-side connection portion 22. . In the illustrated example, the second antenna 40 made of a dipole antenna is an example in which the element shape of the dipole is configured in an L shape. For example, if the second antenna 40 is disposed inside the first antenna 30, the area occupied by the antenna element can be further reduced. More specifically, as shown in the figure, the second antenna 40 is disposed inside the first antenna 30, and the tip end of the first antenna 30 has a meander at a position that is not related to the position of the second antenna 40. What is necessary is just to be bent in a shape. In the illustrated example, the second antenna 40 is configured as an antenna in the 2.45 GHz band.

  The flexible cable 50 connects the common connection port 20 and the antenna module substrate 60 on which circuits for driving the first antenna 30 and the second antenna 40 are mounted. In the illustrated example, an antenna module substrate 60 for driving the first antenna 30 and the first antenna 40 is stacked on the back surface of the antenna substrate 10. The flexible cable 50 is connected between one side of the antenna substrate 10 and one side of the antenna module substrate 60 corresponding thereto. The flexible cable 50 is formed by forming a signal line with a conductive foil on a film-like insulator. Since the common connection port 20 and the power feeding portion of the antenna module substrate 60 are connected by the flexible cable 50, the flexible cable 50 also functions as an antenna element. Therefore, if the frequency band is the same, the lengths of the first antenna 30 and the second antenna 40 on the antenna substrate 10 can be shortened accordingly, so that the antenna substrate 10 can be further downsized. . The flexible cable 50 may be directly electrically connected to the common connection port 20 and the antenna module substrate 60 by solder or the like, or may be connected by a flat connector for a flexible cable.

  In addition, assembling is improved by aligning the position of the common connection port 20 and the position of the portion of the antenna module substrate 60 where the flexible cable 50 is connected as shown in the drawing.

  As described above, the RFID reader / writer of the present invention can be miniaturized because the antenna portion and the antenna module substrate are connected by the flexible cable, and the flexible cable is also used as the antenna element. Further, the antenna substrate and the antenna module substrate can be reduced. It is possible to reduce the thickness by stacking.

  Next, an RFID reader / writer antenna according to a second embodiment of the present invention will be described with reference to FIG. FIG. 3 is a schematic plan view for explaining an RFID reader / writer antenna according to a second embodiment of the present invention. In the figure, the parts denoted by the same reference numerals as those in FIG. The RFID reader / writer antenna of the second embodiment of the present invention is configured such that the first antenna 30 and the second antenna 40 are configured as a common dipole antenna. For example, in the illustrated example, elements are arranged with reference to the first antenna 30 in the 950 MHz band, and the 2.45 GHz band is also received using this element. When the first frequency band is the 950 MHz band and the second frequency band is the 2.45 GHz band, the element length of the first antenna 30 is approximately four times the element length of the second antenna. Become. Therefore, it is possible to share the first antenna 30 and the second antenna 40 within a range in which the sensitivity level is allowable.

  As described above, the RFID reader / writer antenna according to the second embodiment of the present invention can be further reduced in size by using the first antenna and the second antenna as a common dipole antenna.

  Next, an RFID reader / writer antenna according to a third embodiment of the present invention will be described with reference to FIG. FIG. 4 is a schematic perspective view for explaining an RFID reader / writer antenna according to a third embodiment of the present invention. In the figure, the parts denoted by the same reference numerals as those in FIG. The RFID reader / writer antenna of the third embodiment of the present invention is capable of transmitting and receiving data using three frequency bands. As shown in the figure, the RFID reader / writer antenna of the third embodiment of the present invention is the same as the RFID reader / writer antenna of the first embodiment, but also the second connection port 70, the third antenna 80, and the second flexible antenna. A cable 90 is added. The antenna module substrate 60 is configured to be able to drive antennas of three frequency bands in accordance with this.

  The second connection port 70 is disposed on the antenna substrate 10 and includes a second hot side connection portion 71 and a second ground side connection portion 72. In the illustrated example, the second connection port 70 is arranged at a position different from the common connection port 20. A third antenna 80 and a second flexible cable 90 which will be described later are connected to the second connection port 70.

  The third antenna 80 is a loop antenna corresponding to the third frequency band extending from the second connection port 70. For example, the third frequency band may be 13.56 MHz. The third antenna 80 is, for example, a quadrangular multi-turn loop antenna as illustrated. The arrangement position of the third antenna 80 is not particularly limited to that in the illustrated example, and it is sufficient that the third antenna 80 is isolated from the first antenna 30 and the second antenna 40.

  The second flexible cable 90 connects between the second connection port 70 and the antenna module substrate 60 for driving the third antenna 80. The 2nd flexible cable 90 showed what was comprised on the same film-like insulator as the 1st flexible cable 50 in the example of illustration. Thereby, assemblability improves. Here, it is preferable that the first flexible cable 50 and the second flexible cable 90 are arranged so that the hot-side wiring and the ground-side wiring are arranged in parallel, and the ground-side wirings are close to each other. That is, two ground side wirings are arranged inside, and hot side wirings are arranged on both sides thereof. Thereby, isolation can be further improved. At this time, adjacent ground-side wirings can be used as a common wiring.

  In the illustrated example, the third antenna 80 is disposed near the tip of the first antenna 30. Further, a cornering portion 81 for isolation with respect to the first antenna 30 and / or the second antenna 40 is provided in a part of the third antenna 80 formed of a quadrangular loop antenna. As a result, the isolation can be further improved, and as a result, the third antenna 80 can be disposed closer to the first antenna 30 and the second antenna 40.

  Further, an impedance matching element 82 is disposed in a space formed by the chamfered portion 81. Specifically, the impedance matching element 82 is disposed in a space formed by the cornering portion 81 of the third antenna 80 formed of a quadrangular loop antenna. The impedance matching element 82 is for matching the third antenna 80 and the feed line, and is composed of, for example, a capacitor or a coil. Such an impedance matching element 82 is generally arranged on an antenna substrate, but in the RFID reader / writer antenna of the present invention, by arranging it in a space vacated by the cornering portion 81, Space saving of the antenna substrate 10 is possible.

  With such a configuration, it is possible to route the feed line from a certain direction without complicating the wiring more than necessary, and it is possible to reduce variations in antenna characteristics. Similarly to the flexible cable 50, the second flexible cable 90 may be directly electrically connected to the second connection port 70 and the antenna module substrate 60 by solder or the like, or by a flat connector for the flexible cable or the like. It may be connected.

  As described above, the RFID reader / writer antenna according to the third embodiment of the present invention can be reduced in size and thickness by arranging the antennas of the three frequency bands on the antenna substrate.

  Next, an RFID reader / writer antenna according to a fourth embodiment of the present invention will be described with reference to FIG. FIG. 5 is a schematic plan view for explaining an RFID reader / writer antenna according to a fourth embodiment of the present invention. In the figure, the parts denoted by the same reference numerals as those in FIG. In the RFID reader / writer antenna of the fourth embodiment of the present invention, the third antenna 80 is disposed inside the first antenna 30. More specifically, the first antenna 30 is arranged symmetrically with respect to a perpendicular passing through the center of the line connecting the hot-side connection portion 21 and the ground-side connection portion 22, and near the periphery of the antenna substrate 10. It is arranged along with a space inside. Therefore, by arranging the third antenna 80 in this space, the size of the antenna substrate 10 can be further reduced.

  In the third and fourth embodiments, the first antenna and the second antenna are provided separately. However, the present invention is not limited to this, and the first antenna as in the second embodiment. Even if the second antenna is a common dipole antenna, the third antenna can be arranged.

  In the embodiment described so far, the connection between the antenna substrate and the antenna module substrate is performed by a flexible cable. Next, an example in which the substrate on which the antenna is arranged is a flexible substrate will be described.

  FIG. 6 is a schematic plan view for explaining an RFID reader / writer antenna according to a fifth embodiment of the present invention. In the figure, the parts denoted by the same reference numerals as those in FIG. As shown in the figure, the antenna for RFID reader / writer according to the fifth embodiment of the present invention is mainly composed of a flexible substrate 15, a first antenna 85, and a second antenna 45. The RFID reader / writer antenna having such a configuration is connected via a connection port 75 such as a flat connector provided on the antenna module substrate 60 for driving the antenna and the common connection port 26.

  First, the connection port 75 is provided on the antenna module substrate 60. The connection port 75 has a hot side connection part and a ground side connection part. The connection port 75 is connected to a first antenna 85 corresponding to a first frequency band described later. More specifically, the connection port 75 may be configured by, for example, a flat connector.

  The common connection port 26 is also provided on the antenna module substrate 60. The common connection port 26 has a hot side connection part. The common connection port 26 is connected to a second antenna 45 corresponding to a second frequency band and a third frequency band described later. More specifically, the common connection port 26 may be constituted by a flat connector, for example.

  Note that the connection port 75 and the common connection port 26 are preferably arranged as far apart as possible in order to achieve isolation.

  And the 1st antenna 85 consists of a loop antenna corresponding to a 1st frequency band. The first antenna 85 is disposed on the flexible substrate 15 and connected to the connection port 75. The first antenna 85 in the illustrated example is a substantially quadrangular loop antenna, and has a chamfered portion 88 in a part thereof. An impedance matching element 82 is disposed in a space formed by the cornering portion 88. The first antenna 85 acts as an antenna element including the line 86 connected to the connection port 75. The first frequency band supported by the first antenna 85 is, for example, 13.56 MHz. In the illustrated example, a substantially quadrangular loop antenna is shown, but the present invention is not limited to this, and various shapes such as a circular shape can be applied to the loop antenna.

  The second antenna 45 is arranged on the flexible substrate 15 and corresponds to the second frequency band and the third frequency band, and is composed of a modified monopole antenna that branches in the middle. The tip portions 46 and 47 branched in the middle of the second antenna 45 are arranged on the side far from the first antenna 85. That is, in the drawing of FIG. 6, the distal end portion 46 is disposed on the farthest side in the right direction of the first antenna 85, and the distal end portion 47 is on the farthest side in the downward direction of the first antenna 85. Has been placed. The second antenna 45 acts as an antenna element including the line 48 connected to the common connection port 26. In the illustrated example, the second antenna 45 is configured in a meander shape at a point where it branches off in the middle. The second antenna 45 is disposed on the side of the first antenna 85 so as not to surround the first antenna 85. That is, the second antenna 45 is branched in a substantially Z shape, and is arranged with a predetermined gap from two sides of the first antenna 85. Further, the second antenna 45 has one end portion branched in the middle of which the line 86 of the first antenna 85 connected to the connection port 75 and the line 48 of the second antenna 45 connected to the common connection port 26. It is comprised so that it may be arrange | positioned between. By arranging in this way, it is possible to secure isolation between the first antenna 85 and the second antenna 45 and to reduce the size of the flexible substrate 15. The second frequency band to which the second antenna 45 corresponds is, for example, a 950 MHz band, and the third frequency band may be, for example, a 2.45 GHz band. For example, the element length of the second antenna 45 may be adjusted so as to be an integral multiple of the element length on the 950 MHz band side.

  The RFID reader / writer antenna of the fifth embodiment of the present invention thus configured can be very small and thin while being compatible with three frequency bands, and can be applied to, for example, a portable terminal. Is also possible. Also in the case of the fifth embodiment, it is also possible to dispose the flexible substrate so as to overlap the antenna module substrate as in the fourth embodiment. In this case, what is necessary is just to interpose what consists of material which has magnetic permeability, such as a magnetic material sheet, between a flexible substrate and an antenna module substrate if necessary.

  Note that the RFID reader / writer antenna of the present invention is not limited to the above-described illustrated examples, and various modifications can be made without departing from the scope of the present invention.

DESCRIPTION OF SYMBOLS 10 Antenna board | substrate 15 Flexible board 20 Common connection port 21 Hot side connection part 22 Ground side connection part 25 Pattern for impedance matching 26 Common connection port 30 1st antenna 40 2nd antenna 45 2nd antenna 50 Flexible cable 60 Antenna module board 70 Connection port 71 Hot side connection part 72 Ground side connection part 75 Connection port 80 Third antenna 81 Chamfer part 82 Impedance matching element 85 First antenna 88 Chamfer part 90 Flexible cable

Claims (8)

An RFID reader / writer antenna corresponding to two or more frequency bands, wherein the RFID reader / writer antenna is:
An antenna substrate;
A common connection port disposed on the antenna substrate and having a hot-side connection portion and a ground-side connection portion;
A first antenna extending from the common connection port , which corresponds to a first frequency band and is perpendicular to a perpendicular line passing through a center of a line connecting the hot side connection portion and the ground side connection portion in the antenna substrate plane. A first antenna comprising a dipole antenna arranged symmetrically;
A second antenna extending from the common connection port, corresponding to a second frequency band higher than the first frequency band, and a line connecting the hot side connection part and the ground side connection part in the antenna substrate plane A second antenna comprising a dipole antenna arranged symmetrically with respect to a perpendicular passing through the center;
A flexible cable for connecting between the common connection port and an antenna module substrate on which a circuit for driving the first antenna and the second antenna is mounted, and a line of the flexible cable is a dipole antenna of the first antenna and acts as a part of the second antenna of the dipole antenna, the first antenna in the whole, including the flexible cable is configured such that the second antenna corresponding to a first frequency band corresponding to the second frequency band Flexible cable ,
An RFID reader / writer antenna comprising:   2. The RFID reader / writer antenna according to claim 1, wherein the first antenna and the second antenna are a common dipole antenna. The RFID reader / writer antenna according to claim 1 or 2, further comprising:
A second connection port disposed on the antenna substrate and having a second hot side connection portion and a second ground side connection portion;
A third antenna extending from the second connection port, the third antenna comprising a loop antenna corresponding to a third frequency band lower than the first frequency band ;
A second flexible cable for connecting between the second connection port and an antenna module substrate on which a circuit for driving the third antenna is mounted, the second flexible cable line of the third antenna A second flexible cable that acts as part of a dipole antenna and is configured such that the third antenna as a whole, including the second flexible cable, corresponds to the third frequency band ;
An RFID reader / writer antenna comprising:   4. The RFID reader / writer antenna according to claim 3, wherein the third antenna is a substantially quadrangular loop antenna, and a part of the antenna is an isolation angle with respect to the first antenna and / or the second antenna. An RFID reader / writer antenna comprising a take-up portion.   5. The RFID reader / writer antenna according to claim 1, wherein the antenna substrate is arranged with respect to an antenna module substrate on which circuits for driving the first antenna and the second antenna are placed. An RFID reader / writer antenna characterized by being stacked. An RFID reader / writer antenna corresponding to two or more frequency bands, wherein the RFID reader / writer antenna is:
A flexible substrate;
Connected to a connection port having a hot-side connection portion and a ground-side connection portion provided on the antenna module substrate, which is disposed on the flexible substrate and on which a circuit for driving an antenna is placed, and corresponds to the first frequency band A first antenna comprising a loop antenna, wherein a flexible substrate line extending to a connection port acts as part of an antenna element of the first antenna;
A second connection higher than the first frequency band is connected to a common connection port that is disposed on the flexible substrate and has a hot-side connection provided on an antenna module substrate on which a circuit for driving an antenna is placed. It corresponds to the third frequency band higher than the frequency band and the second frequency band, and is a second antenna composed of a modified monopole antenna that branches in the middle, and each tip portion that branches in the middle of the second antenna A second antenna disposed on a side far from the first antenna, and a line of a flexible substrate extending to the connection port acts as a part of the second antenna element;
An RFID reader / writer antenna comprising:   7. The RFID reader / writer antenna according to claim 6, wherein the second antenna is arranged on a side portion of the first antenna so as not to surround the first antenna.   8. The RFID reader / writer antenna according to claim 6 or claim 7, wherein the second antenna is connected to a common connection port and a line of the first antenna where one end portion branched in the middle is connected to the connection port. An RFID reader / writer antenna, wherein the antenna is configured to be disposed between lines of connected second antennas.