Reader / writer and antenna size switching method

Abstract

To provide a reader / writer capable of stably communicating with RF tags.SOLUTION: A reader / writer (10) provided herein is a reader / writer (10) for communicating with RF tags (20), and comprises multiple reader / writer-side antennas (11) of different sizes, and a switching unit (154) configured to switch the antenna to an antenna suitable for the size of a tag-side antenna (21) of an RF tag (20) to communicate with from among the multiple reader / writer antennas (11).SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a reader / writer. [Background technology]

[0002] There is known a reader / writer that communicates with a communication medium such as an RF (Radio Frequency) tag in a non-contact manner and reads and writes data from and to the communication medium. For example, Patent Document 1 discloses a reader / writer that communicates data with an IC card by mutual coupling between an antenna means on an IC card side and an antenna means on a reader / writer side, and in which the antenna means on the reader / writer side is provided so as to be capable of changing the communication mode. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2003-162696 A Summary of the Invention [Problem to be solved by the invention]

[0004] If the size of the antenna on the reader / writer side differs from the size of the antenna on the tag side, stable communication may not be possible. The above-mentioned conventional technology cannot deal with the unstable communication caused by such a mismatch in antenna sizes.

[0005] One aspect of the present invention has been made in view of the above problems, and an object of the present invention is to provide a reader / writer capable of stably communicating with an RF tag. [Means for solving the problem]

[0006] In order to solve the above problems, a reader / writer according to one embodiment of the present invention is a reader / writer that communicates with an RF tag, and is equipped with a plurality of reader / writer-side antennas of different sizes, and a switching unit that switches one of the plurality of reader / writer-side antennas to an antenna corresponding to the size of the tag-side antenna of the RF tag with which it communicates.

[0007] In a reader / writer that communicates with an RF tag, if the antenna on the reader / writer side and the antenna on the RF tag side are different sizes, stable communication may not be possible. With the above configuration, the reader / writer can switch the reader / writer side antenna depending on the size of the tag side antenna, allowing stable communication with the RF tag.

[0008] The reader / writer may communicate with the RF tag by electromagnetic coupling.

[0009] The plurality of reader / writer antennas may have the same resonant frequency.

[0010] According to the above configuration, it is possible to eliminate the shift in the resonant frequency caused by changing the antenna size, and therefore the reader / writer can communicate with the RF tag with sufficient antenna transmission power in a predetermined resonant frequency band.

[0011] In addition, the reader / writer may read a tag identifier of the RF tag from the RF tag, and the switching unit may switch the reader / writer antenna based on a correspondence table that associates the tag identifier with the size of the reader / writer antenna.

[0012] According to the above configuration, the reader / writer can switch to an optimal reader / writer antenna by acquiring a tag identifier with a small capacity from the RF tag, which shortens the processing time required for switching the antenna.

[0013] The reader / writer may read size data indicating a corresponding antenna size from the RF tag, and the switching unit may switch the reader / writer side antenna based on the size data.

[0014] According to the above configuration, the reader / writer can write size data indicating the optimal reader / writer antenna when producing RF tags. In other words, there is no need to associate the tag identifiers randomly assigned to each of multiple RF tags with the optimal reader / writer antenna size, making production management easy.

[0015] The reader / writer may obtain image data of an RF tag captured by a camera, and the switching unit may switch the reader / writer antenna based on the image data.

[0016] According to the above configuration, the reader / writer can determine the optimal reader / writer antenna by capturing an image using a camera, thereby shortening the time required for communication with an RF tag.

[0017] In addition, the reader / writer may acquire size data indicating the corresponding antenna size read by a code reader from an optical code attached to an object including the RF tag, and the switching unit may switch the reader / writer side antenna based on the size data.

[0018] According to the above configuration, the reader / writer can determine the optimal reader / writer antenna by reading the optical code, thereby shortening the time required for communication with the RF tag.

[0019] In addition, each of the plurality of reader / writer side antennas may have a number of turns of a coil corresponding to an antenna size so that the plurality of reader / writer side antennas have the same inductance value. In addition, the reader / writer may have a different resonance circuit for each of the reader / writer side antennas so that the resonance frequency of the reader / writer side antenna does not change due to switching.

[0020] In addition, when the plurality of reader / writer antennas are viewed in plan, one of the plurality of reader / writer antennas may be disposed inside the other reader / writer antenna. With the above configuration, it is possible to switch antennas without moving the RF tag.

[0021] In order to solve the above problems, an antenna size switching method according to one embodiment of the present invention is an antenna size switching method for a reader / writer that communicates with an RF tag using an electromagnetic coupling method, and includes an acquisition step of acquiring information regarding the size of the antenna, and a switching step of switching, based on the information, from among a plurality of reader / writer side antennas possessed by the reader / writer, to an antenna corresponding to the antenna size of the RF tag. Effect of the Invention

[0022] According to one aspect of the present invention, stable communication with an RF tag is possible. [Brief description of the drawings]

[0023] [Figure 1] 1 is a block diagram showing a schematic configuration of a reader / writer and an RF tag according to a first embodiment of the present invention. [Diagram 2] 1 is a schematic diagram showing communication between a reader / writer antenna and a tag antenna by electromagnetic coupling; [Diagram 3] 4 is a table showing an example of the configuration of data stored in a tag-side memory unit of the RF tag. [Figure 4] 6 is a flowchart showing an example of processing by the reader / writer. [Diagram 5] 10 is a table showing an example of the configuration of data stored in a tag-side memory unit of an RF tag with which a reader / writer according to a second embodiment of the present invention communicates. [Figure 6] 6 is a flowchart showing an example of processing by the reader / writer. [Figure 7] FIG. 11 is a schematic diagram showing a reader / writer and an RF tag according to a third embodiment of the present invention. [Figure 8] 6 is a flowchart showing an example of processing by the reader / writer. [Figure 9] FIG. 11 is a schematic diagram showing a reader / writer and an RF tag according to a fourth embodiment of the present invention. [Figure 10] 6 is a flowchart showing an example of processing by the reader / writer. [Figure 11] FIG. 2 is a plan view showing a configuration of a plurality of reader / writer-side antennas. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] Hereinafter, an embodiment according to one aspect of the present invention (hereinafter also referred to as "the present embodiment") will be described with reference to the drawings. However, the present embodiment described below is merely an example of the present invention in every respect. It goes without saying that various improvements and modifications can be made without departing from the scope of the present invention. In other words, in implementing the present invention, a specific configuration according to the embodiment may be appropriately adopted.

[0025] [Embodiment 1] §1 Examples of application Fig. 1 is a block diagram showing a schematic configuration of a reader / writer 10 and an RF tag 20 according to a first embodiment of the present invention. First, an example of a situation in which the present invention is applied will be described with reference to Fig. 1. The reader / writer 10 according to this embodiment is used to write and read data to an RF tag 20. The RF tag 20 is attached to a workpiece (object) and records the work content and the like for the workpiece.

[0026] The reader / writer 10 writes and reads data to the RF tag 20 via electromagnetically coupled antennas provided on the reader / writer 10 and the RF tag 20. If the antenna on the reader / writer side and the antenna on the RF tag side are different in size, stable communication may not be possible (see FIG. 2). Therefore, it is desirable that the size of the antenna on the reader / writer side is approximately the same as the size of the antenna on the RF tag.

[0027] 1 shows only one RF tag for the reader / writer 10, in reality the reader / writer 10 writes and reads data to multiple RF tags. If the multiple RF tags have different antenna sizes, the reader / writer 10 must communicate with the RF tags using antennas that correspond to the respective antenna sizes.

[0028] A reader / writer 10 according to an embodiment of the present invention includes multiple reader / writer antennas 11 of different sizes, and can switch between the multiple reader / writer antennas 11a to 11c according to the size of the tag antenna 21 of the RF tag with which it communicates. This allows the reader / writer 10 to stably communicate with the RF tag by switching the antenna according to the antenna size of the RF tag.

[0029] §2 Configuration example Next, the configurations of the reader / writer 10 and the RF tag 20 according to the first embodiment of the present invention will be described below with reference to FIG.

[0030] The RF tag 20 includes a tag antenna 21, a tag control unit 22, and a tag memory unit 23. The tag antenna 21 (antenna coil) transmits and receives data to and from the reader / writer antenna 11 of the reader / writer 10 by electromagnetic induction. The tag control unit 22 receives a command from the reader / writer 10 via the tag antenna 21 (and a resonant circuit and a modulation / demodulation circuit, not shown). The tag control unit 22 reads out a predetermined address in the tag memory unit 23 based on the command, or writes data received following the command to a predetermined address in the tag memory unit 23. The tag memory unit 23 includes a UID area 231 and a user area 232. The configuration of the tag memory unit 23 will be described later with reference to FIG. 3.

[0031] The reader / writer 10 includes a reader / writer antenna 11, a resonant circuit 12, a switching circuit 13, a modulation / demodulation circuit 14, and a reader / writer control unit 15. In the example of FIG. 1, the reader / writer 10 includes three sets of reader / writer antennas, resonant circuits, and switching circuits that correspond to each other. That is, the reader / writer antenna 11 (antenna coil) includes a first reader / writer antenna 11a, a second reader / writer antenna 11b, and a third reader / writer antenna 11c. The resonant circuit 12 includes a first resonant circuit 12a, a second resonant circuit 12b, and a third resonant circuit 12c. The switching circuit 13 includes a first switching circuit 13a, a second switching circuit 13b, and a third switching circuit 13c. The number of sets of reader / writer antennas, resonant circuits, and switching circuits is not limited to this.

[0032] The modulation / demodulation circuit 14 is connected to the multiple resonant circuits 12a-12c connected in parallel to the multiple reader / writer antennas 11a-11c connected in parallel to each other. The multiple resonant circuits 12a-12c are connected to the corresponding multiple reader / writer antennas 11a-11c via the corresponding multiple switching circuits 13a-13c.

[0033] The reader / writer antenna 11 transmits and receives data to and from the tag antenna 21 by electromagnetic induction. The reader / writer antennas 11a to 11c may each have a different antenna size. The resonant circuit 12 communicates with the RF tag 20 at a predetermined frequency (resonant frequency). The modulation / demodulation circuit 14 modulates transmission data received from the reader / writer control unit 15 into a transmission signal to the RF tag 20. The modulation / demodulation circuit 14 also demodulates a reception signal transmitted from the RF tag 20 and received by the reader / writer antenna 11 into reception data and sends it to the reader / writer control unit 15.

[0034] The reader / writer control unit 15 includes a transmitting / receiving unit 151 , a communication unit 152 , a reader / writer storage unit 153 , and a switching unit 154 .

[0035] The communication unit 152 receives transmission commands (read commands, write commands, etc.) from a higher-level system (controller, personal computer, etc.) to the RF tag 20. The communication unit 152 outputs the transmission command to the modulation / demodulation circuit 14 via the transmission / reception unit 151. The communication unit 152 also receives a response signal of the RF tag 20 input from the modulation / demodulation circuit 14 via the transmission / reception unit 151. The communication unit 152 outputs the response signal of the RF tag to the higher-level system.

[0036] The reader / writer-side storage unit 153 stores a correspondence table D1 (information on antenna size) that associates "UID data (tag identifier)," which is data unique to each RF tag 20, with the "size of the reader / writer-side antenna 11." Note that a host system may have the correspondence table D1 instead of the reader / writer-side storage unit 153. Here, the "size of the reader / writer-side antenna 11" may be set so as to be approximately the same as the size of the tag-side antenna 21 provided in the RF tag 20 that stores the "UID data." The size of the reader / writer-side or tag-side antenna refers to, for example, the length of the antenna's external shape (long side or short side), the antenna's diameter, or the antenna's area.

[0037] The switching unit 154 switches to an antenna corresponding to the size of the tag antenna 21 of the RF tag 20 to be communicated among the multiple reader / writer antennas 11a to 11c. That is, the switching unit 154 acquires the correspondence table D1 from the reader / writer storage unit 153 or a higher-level system. The switching unit 154 also acquires UID data as a response signal of the RF tag 20 from the transmitting / receiving unit 151. The switching unit 154 identifies the "size of the reader / writer antenna 11" corresponding to the "UID data" in the correspondence table D1. The switching unit 154 switches to an antenna corresponding to the "size of the reader / writer antenna 11" among the multiple reader / writer antennas 11a to 11c. When switching to, for example, the first reader / writer antenna 11a among the multiple reader / writer antennas 11a to 11c, the switching unit 154 turns on only the first switching circuit 13a among the multiple switching circuits 13a to 13c. In this manner, the switching unit 154 switches to the optimal reader / writer antenna 11 based on the correspondence table D1.

[0038] Note that by changing the antenna size (antenna diameter), the resonant frequency may deviate from a predetermined frequency. Here, in the reader / writer 10, the multiple reader / writer antennas 11a to 11c are connected to multiple resonant circuits 12a to 12c having parameters related to the resonant frequency corresponding to the antenna sizes of the multiple reader / writer antennas 11a to 11c. The parameters related to the resonant frequency include the inductance of the coils and the capacitance of the capacitors in the resonant circuits 12a to 12c. That is, the reader / writer 10 has a different resonant circuit 12 for each reader / writer antenna 11 so that the resonant frequency of the reader / writer antenna 11 does not change due to switching of the switching unit 154. Therefore, the multiple reader / writer antennas 11a to 11c have the same resonant frequency.

[0039] Also, each of the multiple reader / writer antennas 11a to 11c may be an antenna coil with a number of turns corresponding to the antenna size of each of the multiple reader / writer antennas 11a to 11c. That is, each of the multiple reader / writer antennas 11a to 11c may have a number of turns of a coil according to the antenna size so that the multiple reader / writer antennas 11a to 11c have the same inductance value. Therefore, the multiple reader / writer antennas 11a to 11c have the same resonance frequency.

[0040] Fig. 2 is a schematic diagram showing communication between the reader / writer antenna 11 and the tag antenna 21 by the electromagnetic coupling method. Fig. 2 shows, as an example, a case in which the size of the first reader / writer antenna 11a is smaller than the tag antenna 21, the size of the second reader / writer antenna 11b is approximately the same as the tag antenna 21, and the size of the third reader / writer antenna 11c is larger than the tag antenna 21. The reader / writer antenna 11 and the tag antenna 21 are disposed close to each other and face each other, and communicate with each other by mutual induction.

[0041] 2, some of the magnetic field lines generated from the third reader / writer antenna 11c leak outside the tag antenna 21. Therefore, the reader / writer 10 using the third reader / writer antenna 11c may not be able to stably communicate with the RF tag 20. Similarly, when the first reader / writer antenna 11a, which is smaller in size than the tag antenna 21, is used, the tag antenna 21 and the first reader / writer antenna 11a cannot be electromagnetically coupled efficiently.

[0042] On the other hand, the magnetic field lines generated from the second reader / writer antenna 11b pass through the inside of the tag antenna 21. Therefore, the reader / writer 10 using the second reader / writer antenna 11b can communicate with the RF tag 20 stably.

[0043] 3 is a table showing an example of the configuration of data stored in the tag-side storage unit 23. As shown in FIG. 3, the tag-side storage unit 23 includes a UID area 231 for storing UID data and a user area 232 for storing user data. The UID data is data unique to each RF tag 20. The user data is data written by the reader / writer 10, and includes, for example, the work content of the work to which the RF tag 20 is attached. The reader / writer 10 reads out the user data written to a predetermined address in the user area 232, or writes data to a predetermined address in the user area 232.

[0044] §3 Example of operation (Example 1) Fig. 4 is a flowchart showing an example of processing of the reader / writer 10 according to the present embodiment. Next, processing (communication processing) in which the reader / writer 10 switches to an optimal reader / writer-side antenna based on the correspondence table D1 and communicates with the RF tag 20 will be described below with reference to Fig. 4.

[0045] 4, in the antenna size switching method according to the present embodiment, first, the switching unit 154 sets the reader / writer antenna 11 to the default first reader / writer antenna 11a (step S11). That is, the switching unit 154 turns on only the first switching circuit 13a among the multiple switching circuits 13a to 13c.

[0046] Next, the upper system issues a read command to the UID area 231 (step S12). The reader / writer 10 transmits a transmission signal based on the read command received from the upper system to the RF tag 20 via the default first reader / writer antenna 11a.

[0047] Here, if the received signal from the RF tag 20 is equal to or higher than a predetermined level and the reader / writer 10 has received the UID data normally, the reader / writer control unit 15 determines that communication with the RF tag 20 has been successful. If the received signal from the RF tag 20 is below the predetermined level and the reader / writer 10 has not received the UID data normally, the reader / writer control unit 15 determines that communication with the RF tag 20 has failed.

[0048] If the reader / writer 10 fails to communicate with the RF tag 20 (NO in step S13), the reader / writer control unit 15 judges whether or not communication with the RF tag 20 has been established via all the reader / writer antennas 11 (step S14). If communication with the RF tag 20 has been established via all the reader / writer antennas 11 (YES in step S14), the reader / writer control unit 15 judges that communication processing has failed (step S20). If communication with the RF tag 20 has not been established via all the reader / writer antennas 11 (NO in step S14), the switching unit 154 switches to a reader / writer antenna other than the antenna used for communication (step S15), and performs step S12 again.

[0049] For example, if the reader / writer 10 fails to communicate with the RF tag 20 via the default first reader / writer antenna 11a, the switching unit 154 switches to the second reader / writer antenna 11b. Next, if the reader / writer 10 fails to communicate with the RF tag 20 via the second reader / writer antenna 11b, the switching unit 154 switches to the third reader / writer antenna 11c. Next, if the reader / writer 10 fails to communicate with the RF tag 20 via the third reader / writer antenna 11c, the reader / writer control unit 15 determines that the communication process has failed.

[0050] If the reader / writer 10 succeeds in communicating with the RF tag 20 (YES in step S13), the switching unit 154 acquires the correspondence table D1 from the reader / writer storage unit 153 or a higher-level system (acquisition step). The switching unit 154 switches to the optimal reader / writer antenna 11 based on the correspondence table D1 (switching step S16). That is, the switching unit 154 identifies the "size of the reader / writer antenna 11" that corresponds to the "UID data" received from the RF tag 20 in the correspondence table D1. The switching unit 154 switches to the antenna that corresponds to the "size of the reader / writer antenna 11" among the multiple reader / writer antennas 11a to 11c.

[0051] Next, the upper system issues an access command (a read command or a write command) to the user area 232 (step S17). The reader / writer 10 transmits a transmission signal based on the access command received from the upper system to the RF tag 20 via the optimal reader / writer antenna 11.

[0052] If the reader / writer 10 fails to communicate with the RF tag 20 via the optimal reader / writer antenna 11 (NO in step S18), the reader / writer control unit 15 determines that the communication process has failed (step S20). If the reader / writer 10 succeeds in communicating with the RF tag 20 via the optimal reader / writer antenna 11 (YES in step S18), the reader / writer control unit 15 determines that the communication process has succeeded (step S19).

[0053] As described above, the reader / writer 10 according to this embodiment can stably communicate with the RF tag 20 by switching to an optimal reader / writer antenna based on the correspondence table D1. That is, the reader / writer 10 can switch to an antenna, among the multiple reader / writer antennas 11a to 11c, that corresponds to the size of the tag antenna 21 of the RF tag with which it communicates.

[0054] Moreover, the reader / writer 10 according to this embodiment can switch to the optimal reader / writer-side antenna 11 by acquiring UID data, which has a smaller capacity than user data, from the RF tag 20. In other words, the processing time required for switching the antenna can be made shorter than that of the reader / writer 10 according to the second embodiment described later.

[0055] [Embodiment 2] Other embodiments of the present invention will be described below. For ease of explanation, the same reference numerals are given to members having the same functions as those described in the above embodiment, and the description thereof will not be repeated.

[0056] 5 is a table showing an example of the configuration of data stored in the tag-side storage unit 23 of the RF tag 20 with which the reader / writer 10 according to the second embodiment of the present invention communicates. The tag-side storage unit 23 according to this embodiment includes a UID area 231 and a user area 232, as in the first embodiment. The user area 232 according to this embodiment differs from the user area 232 according to the first embodiment in that size data D2 (information about the size of the antenna) indicating the corresponding antenna size is stored at address A1. Here, the size data D2 indicating the corresponding antenna size may be data indicating the size of the tag-side antenna 21, or may be data indicating the size of the reader / writer-side antenna 11 that can stably communicate with the tag-side antenna 21.

[0057] The switching unit 154 according to this embodiment differs from the first embodiment in that it switches the reader / writer antenna 11 based on size data D2 read from the user area 232 instead of the correspondence table D1.

[0058] (Example 2) Fig. 6 is a flowchart showing an example of processing of the reader / writer 10 according to the present embodiment. The processing in which the reader / writer 10 switches to an optimal reader / writer-side antenna based on the size data D2 and communicates with the RF tag 20 will be described below with reference to Fig. 6.

[0059] 6, in the antenna size switching method of this embodiment, first, S11 to S15 are performed in the same manner as in embodiment 1. If the reader / writer 10 succeeds in communicating with the RF tag 20 (YES in step S13), the upper system issues a read command to address A1 in the user area 232 (step S31). The reader / writer 10 transmits a transmission signal based on the read command received from the upper system to the RF tag 20 via, for example, the reader / writer-side antenna 11 when communication was successful in S13.

[0060] The process of the reader / writer 10 based on the read command to address A1 of the user area 232 (steps S32 to S34) is the same as the process of the reader / writer 10 based on the read command to the UID area 231 (steps S13 to S15). That is, if the reader / writer 10 fails to communicate with the RF tag 20 (NO in step S32), the reader / writer control unit 15 judges whether or not communication with the RF tag 20 has been established via all the reader / writer antennas 11 (step S33). If communication with the RF tag 20 has been established via all the reader / writer antennas 11 (YES in step S33), the reader / writer control unit 15 judges that the communication process has failed (step S39). If communication with the RF tag 20 has not been performed via all of the reader / writer antennas 11 (NO in step S33), the switching unit 154 switches to a reader / writer antenna other than the antenna used for communication (step S34) and performs step S31 again.

[0061] If the reader / writer 10 succeeds in communicating with the RF tag 20 (YES in step S32), the reader / writer 10 receives size data D2 from the RF tag 20 as received data (acquisition step). The switching unit 154 switches to the optimal reader / writer antenna 11 based on the size data D2 (switching step S35). That is, the switching unit 154 switches to an antenna corresponding to the size of the tag antenna 21 or the size of the reader / writer antenna 11 indicated in the size data D2.

[0062] Next, the upper system issues an access command to an address other than address A1 in the user area 232 (step S36). The reader / writer 10 transmits a transmission signal based on the access command received from the upper system to the RF tag 20 via the optimal reader / writer antenna 11.

[0063] If the reader / writer 10 fails to communicate with the RF tag 20 via the optimal reader / writer antenna 11 (NO in step S37), the reader / writer control unit 15 determines that the communication process has failed (step S39). If the reader / writer 10 succeeds in communicating with the RF tag 20 via the optimal reader / writer antenna 11 (YES in step S37), the reader / writer control unit 15 determines that the communication process has succeeded (step S38).

[0064] The reader / writer 10 according to this embodiment can write size data D2 indicating an optimal reader / writer antenna 11 when the RF tag 20 is produced. In other words, compared to the RF tag 20 according to the first embodiment, there is no need to associate the UID randomly assigned to each of the RF tags 20 with the optimal size of the reader / writer antenna 11, making production management easier.

[0065] [Embodiment 3] Other embodiments of the present invention will be described below. For ease of explanation, the same reference numerals are given to members having the same functions as those described in the above embodiment, and the description thereof will not be repeated.

[0066] 7 is a schematic diagram showing a reader / writer 10 and an RF tag 20 according to a third embodiment of the present invention. As shown in FIG. 7, a camera 30 captures an image of an RF tag 20 attached to a workpiece 60. A host system 50 receives image data D3 (information related to the size of the antenna) of the RF tag 20 from the camera 30, and transmits the image data D3 to the reader / writer 10. The reader / writer 10 acquires the image data D3 of the RF tag 20 captured by the camera 30.

[0067] The switching unit 154 according to this embodiment differs from the first embodiment in that it switches the reader / writer antenna 11 based on image data D3 instead of the correspondence table D1.

[0068] (Example 3) Fig. 8 is a flowchart showing an example of processing of the reader / writer 10 according to the present embodiment. The processing in which the reader / writer 10 switches to an optimal reader / writer-side antenna based on image data D3 and communicates with the RF tag 20 will be described below with reference to Fig. 8.

[0069] 8, in the antenna size switching method of the present embodiment, first, the camera 30 captures an image of the RF tag 20 (step S51). The host system 50 receives image data D3 of the RF tag 20 from the camera 30 and transmits the image data D3 to the reader / writer 10.

[0070] Next, the reader / writer 10 acquires image data D3 from the upper system 50 (acquisition step). If the reader / writer 10 succeeds in acquiring the image data D3 (YES in step S52), the reader / writer control unit 15 identifies the size of the RF tag 20 from the image data D3 (step S53). If the reader / writer 10 fails to acquire the image data D3 (NO in step S52), the reader / writer control unit 15 determines that the communication process has failed (step S60).

[0071] Next, the switching unit 154 switches to the optimal reader / writer antenna 11 based on the size of the RF tag 20 identified from the image data D3 (switching step S54). For example, the switching unit 154 identifies the size of the tag antenna 21 from the size of the RF tag 20, and switches to the reader / writer antenna 11 corresponding to the size of the tag antenna 21.

[0072] Next, the upper system 50 issues a read command to the UID area 231 (step S55). The reader / writer 10 transmits a transmission signal based on the read command received from the upper system 50 to the RF tag 20 via the optimal reader / writer antenna 11.

[0073] If the reader / writer 10 fails to communicate with the RF tag 20 via the optimal reader / writer antenna 11 (NO in step S56), the reader / writer control unit 15 determines that the communication process has failed (step S60). If the reader / writer 10 succeeds in communicating with the RF tag 20 via the optimal reader / writer antenna 11 (YES in step S56), the upper system 50 issues an access command to the user area 232 (step S57). The process of the reader / writer 10 based on the access command to the user area 232 (steps S57 to S58) is the same as the process of the reader / writer 10 based on the read command to the UID area 231 (steps S55 to S56). If the reader / writer 10 succeeds in communicating with the RF tag 20 based on the access command to the user area 232 (YES in step S58), the reader / writer control unit 15 determines that the communication process has succeeded (step S59).

[0074] The reader / writer 10 according to this embodiment can determine the optimal reader / writer antenna 11 by capturing an image using the camera 30. Therefore, compared to the first and second embodiments, the communication time with the RF tag can be shortened.

[0075] [Embodiment 4] Other embodiments of the present invention will be described below. For ease of explanation, the same reference numerals are given to members having the same functions as those described in the above embodiment, and the description thereof will not be repeated.

[0076] Fig. 9 is a schematic diagram showing a reader / writer 10 and an RF tag 20 according to a fourth embodiment of the present invention. As shown in Fig. 9, an optical code 62 is provided on the side of a pallet 61 on which a workpiece 60 to which an RF tag 20 is attached is loaded. The code reader 40 reads the identification information of the RF tag 20, including size data D2, from the optical code 62. The upper system 50 receives the size data D2 from the code reader 40 and transmits the size data D2 to the reader / writer 10. The reader / writer 10 acquires the size data D2 read by the code reader 40 from the optical code 62.

[0077] A switching unit 154 according to this embodiment differs from that of the first embodiment in that it switches the reader / writer antenna 11 based on size data D2 read from the optical code 62 instead of the correspondence table D1.

[0078] (Example 4) Fig. 10 is a flowchart showing an example of processing of the reader / writer 10 according to the present embodiment. The processing in which the reader / writer 10 switches to an optimal reader / writer-side antenna based on the size data D2 and communicates with the RF tag 20 will be described below with reference to Fig. 10.

[0079] 10, in the antenna size switching method of the present embodiment, first, the code reader 40 reads the size data D2 from the optical code 62 (step S71). The upper system 50 receives the size data D2 from the code reader 40 and transmits the size data D2 to the reader / writer 10.

[0080] Next, the reader / writer 10 acquires size data D2 from the upper system 50 (acquisition step). If the reader / writer 10 succeeds in acquiring the size data D2 (YES in step S72), the switching unit 154 switches to the optimal reader / writer antenna 11 based on the size data D2 (switching step S73). If the reader / writer 10 fails to acquire the size data D2 (NO in step S72), the reader / writer control unit 15 determines that the communication process has failed (step S60). After S73, the reader / writer 10 performs S55 to S60 in the same manner as in the third embodiment.

[0081] The reader / writer 10 according to this embodiment can determine the optimal reader / writer antenna 11 by reading the optical code 62. Therefore, the communication time with the RF tag can be shortened compared to the first and second embodiments. (Modification)

[0082] Fig. 11 is a plan view showing the configuration of multiple reader / writer antennas 11a to 11c. As shown in Fig. 11, in a plan view of the multiple reader / writer antennas 11a to 11c, the second reader / writer antenna 11b smaller in size than the third reader / writer antenna 11c may be arranged inside the third reader / writer antenna 11c. Similarly, the first reader / writer antenna 11a smaller in size than the second reader / writer antenna 11b may be arranged inside the second reader / writer antenna 11b. With this configuration, the antennas can be switched without moving the RF tag.

[0083] [Software implementation example] The functions of the reader / writer (hereinafter referred to as the "device") are realized by a program for causing a computer to function as the device, and by a program for causing a computer to function as each control block of the device (particularly each part included in the reader / writer side control unit 15).

[0084] In this case, the device includes a computer having at least one control device (e.g., a processor) and at least one storage device (e.g., a memory) as hardware for executing the program. The control device and storage device execute the program to realize each function described in each of the above embodiments.

[0085] The program may be non-transitory and may be recorded in one or more computer-readable recording media. The recording media may or may not be included in the device. In the latter case, the program may be provided to the device via any wired or wireless transmission medium.

[0086] In addition, some or all of the functions of each of the control blocks can be realized by a logic circuit. For example, an integrated circuit in which a logic circuit that functions as each of the control blocks is formed is also included in the scope of the present invention. In addition, the functions of each of the control blocks can be realized by, for example, a quantum computer.

[0087] Furthermore, each process described in each of the above embodiments may be executed by AI (Artificial Intelligence). In this case, the AI ​​may be executed by the control device or another device (for example, an edge computer or a cloud server).

[0088] The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention. [Explanation of symbols]

[0089] 10 Reader / Writer 11 Reader / writer antenna 12 Resonant circuit 13 Switching Circuits 15 Reader / writer control unit 20 RF Tag 21 Tag side antenna 30 Camera 40 Code Reader 60 Work (object) 61 Palettes 62 Optical Code 154 Switching section D1 compatible table D2 Size Data D3 Image data S16, S35, S54, S73 Switching steps

Claims

1. A reader / writer that communicates with an RF tag, A plurality of reader / writer side antennas of different sizes; a switching unit that switches between the plurality of reader / writer antennas and an antenna corresponding to the size of the tag antenna of the RF tag to be communicated; The reader / writer reads the tag identifier of the RF tag from the RF tag, The switching unit switches the reader / writer antenna based on a correspondence table that associates the tag identifier with a size of the reader / writer antenna.

2. A reader / writer that communicates with an RF tag, A plurality of reader / writer side antennas of different sizes; a switching unit that switches between the plurality of reader / writer antennas and an antenna corresponding to the size of the tag antenna of the RF tag to be communicated; the reader / writer reads size data from the RF tag, the size data being data indicating the size of the tag antenna or data indicating the size of a reader / writer antenna capable of stable communication with the tag antenna; The switching unit switches the reader / writer side antenna based on the size data.

3. A reader / writer that communicates with an RF tag, A plurality of reader / writer side antennas of different sizes; a switching unit that switches between the plurality of reader / writer antennas and an antenna corresponding to the size of the tag antenna of the RF tag to be communicated; The reader / writer acquires image data of the RF tag captured by a camera, The switching unit switches the reader / writer side antenna based on the image data.

4. A reader / writer that communicates with an RF tag, A plurality of reader / writer side antennas of different sizes; a switching unit that switches between the plurality of reader / writer antennas and an antenna corresponding to the size of the tag antenna of the RF tag to be communicated; the reader / writer acquires size data, the size data being data indicating the size of the tag antenna or data indicating the size of a reader / writer antenna capable of stable communication with the tag antenna, read by a code reader from an optical code provided on the object including the RF tag; The switching unit switches the reader / writer side antenna based on the size data.

5. The reader / writer according to claim 1 , wherein communication with the RF tag is performed by an electromagnetic coupling method.

6. The reader / writer according to claim 1 , wherein the plurality of reader / writer-side antennas have the same resonant frequency.

7. 7. The reader / writer according to claim 1, wherein each of the plurality of reader / writer antennas has a number of coil turns corresponding to an antenna size so that the plurality of reader / writer antennas have the same inductance value.

8. 7. The reader / writer according to claim 1, wherein each of the reader / writer antennas has a different resonance circuit so that a resonance frequency of the reader / writer antenna does not change due to switching.

9. The reader / writer according to claim 1 , wherein, in a planar view of the plurality of reader / writer-side antennas, one of the plurality of reader / writer-side antennas is arranged inside the other reader / writer-side antenna.

10. A method for switching antenna sizes of a reader / writer that communicates with an RF tag by electromagnetic coupling, comprising: - obtaining information regarding the size of the antenna; a switching step of switching, based on the information, from among a plurality of reader / writer side antennas possessed by the reader / writer, to an antenna corresponding to a size of the tag side antenna of the RF tag; The reader / writer reads the tag identifier of the RF tag from the RF tag, In the switching step, the reader / writer antenna is switched based on a correspondence table in which the tag identifier is associated with a size of the reader / writer antenna.

11. A method for switching antenna sizes of a reader / writer that communicates with an RF tag by electromagnetic coupling, comprising: - obtaining information regarding the size of the antenna; a switching step of switching, based on the information, from among a plurality of reader / writer side antennas possessed by the reader / writer, to an antenna corresponding to a size of the tag side antenna of the RF tag; the reader / writer reads size data from the RF tag, the size data being data indicating the size of the tag antenna or data indicating the size of a reader / writer antenna capable of stable communication with the tag antenna; In the switching step, the reader / writer side antenna is switched based on the size data.

12. A method for switching antenna sizes of a reader / writer that communicates with an RF tag by electromagnetic coupling, comprising: - obtaining information regarding the size of the antenna; a switching step of switching, based on the information, from among a plurality of reader / writer side antennas possessed by the reader / writer, to an antenna corresponding to a size of the tag side antenna of the RF tag; The reader / writer acquires image data of the RF tag captured by a camera, In the switching step, the reader / writer side antenna is switched based on the image data.

13. A method for switching antenna sizes of a reader / writer that communicates with an RF tag by electromagnetic coupling, comprising: - obtaining information regarding the size of the antenna; a switching step of switching, based on the information, from among a plurality of reader / writer side antennas possessed by the reader / writer, to an antenna corresponding to a size of the tag side antenna of the RF tag; the reader / writer acquires size data, the size data being data indicating the size of the tag antenna or data indicating the size of a reader / writer antenna capable of stable communication with the tag antenna, read by a code reader from an optical code provided on the object including the RF tag; In the switching step, the reader / writer side antenna is switched based on the size data.

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