JP4990874B2 - RFID system and control method, apparatus and program in the system - Google Patents

Description

  The present invention relates to an RFID system using a passive RFID (Radio Frequency Identification) tag, and a control method, apparatus and program in the system.

  The passive RFID system is a system that assumes short-distance communication, and even if the communication distance is long, it is about several meters. Further, it is generally used at a moving speed in a stationary state or walking. Therefore, when a reader or a passive RFID tag (hereinafter also simply referred to as a tag) is moving at high speed (for example, when moving at a speed of several tens of kilometers per hour), communication performed between the reader and the passive RFID tag However, the data reading rate may be greatly reduced, and accurate communication becomes difficult.

  A passive RFID tag is simply called a passive tag or the like, but does not have a built-in battery, operates with the transmission power of a signal transmitted from a reader as a power source, and is assigned to each tag according to the transmission signal from the reader. It is a device that transmits information such as an ID (identifier) that is stored and stores the information in an internal storage device.

  Conventionally, as a method for improving the data reading rate of the reader, there is a method of shortening the data transmission interval (see, for example, Patent Document 1), and it is possible to improve the data reading rate as a single reader. . However, when moving at high speed (when moving at a speed of several tens of kilometers per hour), the reader and the tag may be far away from each other in the first place, so even if the data read rate of the reader alone is improved, the entire system As a result, the data reading rate is not improved and communication is difficult.

  Even if multiple readers are simply installed, the number of transmissions and receptions between the reader and the tag can be increased, but the response signal from the tag to the signal transmitted by a reader is received only by the reader that transmitted the signal. Since the data cannot be received by the corresponding reader, the data reading rate is not improved.

  6 to 8 are schematic diagrams for explaining the background art of the present invention, and show an example of a communication pattern in the RFID system. In each figure, (a) is a system configuration diagram, and (b) is a sequence diagram of a communication operation. 6 and 7 show examples of communication in a stationary state, and FIG. 8 shows examples of communication during movement.

  Conventionally, passive RFID systems assume communication in a stationary state, and one or more tags are connected to one reader for communication. FIG. 6 shows a case where one tag communicates with one reader, and FIG. 7 shows a case where two tags communicate with one reader. In FIG. 6, one tag 21 returns a response signal S2 to the signal S1 from the reader 11. As shown in FIG. 7, when there are a plurality of tags, the operation of FIG. 6 is basically repeated for each tag. In FIG. 7, the signal S1 is transmitted from the reader 11 to the tag A22, and the signal S2 is transmitted from the tag A22 to the reader 11. Thereafter, a signal S3 is transmitted from the reader 11 to the tag B23, and a signal S4 is transmitted from the tag B23 to the reader 11. Since the change in the communication environment is small in the stationary state, the operations of FIGS. 6 and 7 are repeated, and the communication is performed stably.

On the other hand, when the reader 11 or the tag 24 shown in FIG. 8 is moving, when the tag 24 receiving the signal S1 from the reader 11 returns a response to the reader 11, it depends on the position of the tag 24 and the reader 11. There is a possibility that the reader 11 cannot receive the signal S2 from the tag 24. If the system has a long communicable distance, the signal can be received even if the reader or tag is moving because the area where the signal can be received is wide. However, the passive RFID system is a system that assumes communication at a short distance, and even if the communication distance is long, it is only about a few meters. Therefore, the probability that the signal cannot be received increases as the moving speed increases. For this reason, when the tag or the reader is moving at a high speed (for example, moving at a speed of several tens of kilometers per hour), the data reading rate is greatly reduced.
JP 2007-272805 A

  Thus, for example, as shown in FIG. 9, a method of improving the data reading rate by using a plurality of readers (in FIG. 9, two readers 12 and 13) and increasing the number of times the reader / tag transmits and receives can be considered. 9A is a system configuration diagram, and FIG. 9B is a sequence diagram of communication operations. In the system shown in this figure, using two readers, the signal S1 is transmitted from the reader A12 and the signal S2 is responded from the tag 24, and the signal S3 is transmitted from the reader B13 and the signal S4 is responded from the tag 24. It has become. However, in the sequence diagram (b) shown in FIG. 9, the response signal S2 from the tag 24 to the signal S1 transmitted from the reader A12 is not received by the reader A12, and communication has failed. Further, the response signal S4 from the tag 24 with respect to the signal S3 transmitted from the reader B13 is not received by the reader B13, and communication has failed. In this way, simply by increasing the number of readers, a response signal from a tag to a signal transmitted by a reader can basically be received only by the reader that transmitted the signal. Data read rate will not improve.

  Further, as shown in FIG. 10, it is conceivable to expand the receivable area by providing a reader dedicated to reception. 10A is a system configuration diagram, and FIG. 10B is a sequence diagram of communication operations. In the example shown in FIG. 10, a reader B15 dedicated to reception is provided in addition to the reader A14 that transmits and receives signals. FIG. 10 shows a case where the signal S1 and the signal S3 are transmitted from the reader A14 to the tag 24, and the response S2 to the signal S1 and the response S4 to the signal S3 are transmitted from the tag 24. In this example, the signals S2 and S4 transmitted from the tag 24 to the reader A14 can be received by another reader B15. In this configuration, even when the reader A14 cannot receive the signal from the tag 24 due to the movement of the tag 24 or the reader A14, the other reader B15 can receive the signals S2 and S4. The data reading rate can be improved. However, in this configuration, the reader that can transmit a signal to the tag 24 is one of the readers A14 and is always a fixed reader. Therefore, when the tag 24 cannot receive a signal from the reader A14 (the signal S3 in FIG. 10). The tag 24 cannot transmit the response signal S4 to the reader A14 or B15.

  As described above, the passive RFID system is a system that assumes short-distance communication, and since the communicable area is small, the data reading rate is greatly reduced when the tag or reader is moving at high speed. There is a problem that it ends up. In the present invention, in a passive RFID system, even when a tag or reader is moving at high speed (for example, about several tens of kilometers per hour), the data reading rate of the entire system is improved by using a plurality of readers. The purpose is to enable communication even during high-speed movement.

  In order to solve the above-described problem, an invention according to claim 1 is an RFID system using a plurality of passive RFID tags, and a plurality of readers capable of transmitting and receiving signals to and from the passive RFID tags, and the readers. A control device for taking cooperation, and when the control device transmits a signal from any one of the plurality of readers, the other reader performs control for receiving only the signal. One of the plurality of readers that has received a signal from the passive RFID tag performs control to transmit the next signal to the passive RFID tag.

  According to a second aspect of the present invention, when the plurality of readers receive a signal transmitted from any one of the plurality of passive RFID tags, the plurality of readers receive the signals. The synthesized signals are synthesized.

  According to a third aspect of the present invention, when the signal is continuously transmitted / received a plurality of times between any one of the plurality of passive RFID tags and the plurality of readers, the control device To select a reader that transmits signals from the plurality of readers to the passive RFID tag for each of a plurality of transmissions, and to synthesize a signal received by the one or more readers a plurality of times. It is characterized by.

  According to a fourth aspect of the present invention, in an RFID system using a plurality of passive RFID tags, a plurality of readers capable of transmitting / receiving signals to / from the passive RFID tags and a control device for establishing cooperation between the readers When any one of the plurality of readers transmits a signal by the control device, the other reader controls to receive only the signal, and from the passive RFID tag One of the plurality of readers that has received this signal performs control to transmit the next signal to the passive RFID tag.

  According to a fifth aspect of the present invention, when the plurality of readers receive a signal transmitted from any one of the plurality of passive RFID tags, the plurality of readers receive the signals. The synthesized signals are synthesized.

  According to a sixth aspect of the present invention, when the signal is continuously transmitted and received a plurality of times between any one of the plurality of passive RFID tags and the plurality of readers, the control device To select a reader that transmits signals from the plurality of readers to the passive RFID tag for each of a plurality of transmissions, and to synthesize a signal received by the one or more readers a plurality of times. It is characterized by.

  The invention according to claim 7 is an RFID system using a plurality of passive RFID tags and a plurality of readers capable of transmitting and receiving signals between the plurality of passive RFID tags. A control device for taking a signal when any one of the plurality of readers transmits a signal to the passive RFID, the other reader performs control to receive only the signal, and One of the readers that has received a signal from a passive RFID tag performs control to transmit the next signal to the passive RFID tag.

  According to an eighth aspect of the present invention, when the control device receives a signal transmitted from any one of the plurality of passive RFID tags, the plurality of readers The received signal is synthesized.

  According to the ninth aspect of the present invention, the control device transmits / receives a signal a plurality of times continuously between any one of the plurality of passive RFID tags and the plurality of readers. A reader that transmits signals from the plurality of readers to the passive RFID tag is selected for each transmission of a plurality of times, and a signal received by the one or more readers a plurality of times is combined. It is characterized by doing.

  According to a tenth aspect of the present invention, when the control device according to the seventh aspect is configured by using a computer, and any one of the plurality of readers transmits a signal in the computer. The other reader performs control to receive only the signal, and one of the readers that has received the signal from the passive RFID tag transmits the next signal to the passive RFID tag. It is characterized by performing.

  In the present invention, when a reader transmits a signal, the control device controls so that the other reader only receives the signal, and one of the readers that has received the signal from the passive RFID tag. Is controlled to transmit the next signal to the passive RFID tag. According to this, since a plurality of readers are controlled in cooperation so that signal transmission is performed from any one reader, the RFID tag can easily receive a transmission signal from the reader. Since the reader that transmits the signal is selected from one of the readers that have received the signal from the RFID tag, the reader can be selected according to the movement state. When the reader or the RFID tag is moving at high speed, the communication environment changes greatly, and the combination of the reader and the RFID tag with good communication conditions always changes. However, according to the present invention, the communication condition is best at each time. Since the reader and the RFID tag can be selected, the reading rate of the reader and tag during high-speed movement can be improved.

  Embodiments according to the present invention will be described in detail with reference to the drawings.

[Embodiment 1]
FIG. 1 shows a configuration example of Embodiment 1 of the present invention. 1A is a system configuration diagram, and FIG. 1B is a communication operation sequence diagram. The system shown in FIG. 1 is an RFID system that uses a plurality of passive RFID tags 24 (only one is shown in FIG. 1, hereinafter referred to as a tag), and transmits and receives signals to and from the tag 24. And a plurality of readers 10a and 10b, and a control device 3 for establishing cooperation between the readers 10a and 10b. In the RFID system of the present embodiment, the reader 10a and the reader 10b are connected to the control device 3 via a wired or wireless communication line (or control line) and controlled by the control device 3. In this configuration, the reader 10a and the reader 10b are controlled so that one reader transmits a signal and the other readers only receive based on an instruction from the control device 3. That is, any one of the reader 10 a and the reader 10 b transmits a predetermined signal to the tag 24 and receives a response signal transmitted from the tag 24 based on an instruction from the control device 3. On the other hand, the reader that has not been instructed to transmit also receives a response signal from the tag 24 in response to a signal transmitted from a different reader, based on an instruction from the control device 3 or information on transmission contents determined in advance. .

  Further, the control device 3 performs control in which one of the readers that has received the signal from the tag 24 transmits the next signal to the tag 24. That is, when the tag 24 returns a response signal to a signal transmitted by either the reader 10a or the reader 10b, and when transmitting / receiving a signal to / from the tag 24, the control device 3 receives the response signal from the tag 24. One of the readers that can be selected is selected, and control is performed to determine the reader to transmit the next signal.

  In the example illustrated in FIG. 1, the reader 10 a transmits a signal S <b> 1 to the tag 24 in accordance with an instruction from the control device 3. Here, the reader 10a and the reader 10b enter a standby state for receiving the response signal S2 from the tag 24 for the signal S1. When the tag 24 receives the signal S1, the tag 24 transmits a response signal S2. In this example, the signal S2 is received only by the reader 10b. The control device 3 selects the reader 10b as the transmission source of the signal S3 to be transmitted next to the tag 24, and the signal S3 is transmitted from the reader 10b. When the tag 24 receives the signal S3, the tag 24 transmits a response signal S4 corresponding thereto. Here, the reader 10a and the reader 10b enter a standby state for receiving the response signal S4 from the tag 24 for the signal S3. In this example, the signal S4 is received only by the reader 10a.

  Thus, in this embodiment, the signal S2 from the tag 24 with respect to the signal S1 from the reader 10a can be received by the reader 10a and the reader 10b, and the data reading rate of the transmission signal from the tag 24 by the reader is improved. Can do. Further, the control device 3 performs control in which the reader 10b that has received the signal S2 from the tag 24 transmits the next signal to be transmitted from the reader 10a or 10b to the tag 24. As a result, the reader 10a that has not received the signal S2 from the tag 24 (that is, the reader 10a and the tag 24 are likely to be in an area where communication is impossible) communicates with the tag 24 as compared with the case where the signal S3 is transmitted. The reader 10b that has a high possibility of being in a possible area can transmit the signal S3. Therefore, the probability that the tag 24 can receive the signal S3 is improved. Therefore, an improvement in the data reading rate of the tag 24 can be expected.

  FIG. 2 shows a configuration of the control device 3 shown in FIG. The control device 3 can be composed of a computer and its peripheral devices and a program executed by the computer, and includes a receiving unit 31, a data processing unit 32, and a reception status storage that are configured by a combination of hardware and software. The unit 33 includes a transmission / reception determination unit 34 and a transmission / reception control unit 35. The receiving unit 31 receives information indicating the reception data received from the tag 24 and information indicating the reception result of the response signal from the tag 24 from each reader 10a, 10b. The data processing unit 32 generates information indicating the content of a signal to be transmitted to the tag 24 based on the received data from the tag 24 included in the information received by the receiving unit 31 and sends the information to the transmission / reception control unit 35. On the other hand, the reception status storage unit 33 stores the reception status at each reader 10a, 10b of the received signal from the tag 24 based on the information received from each reader 10a, 10b by the reception unit 31, and the transmission / reception determination unit 34. Based on the information stored in the reception status storage unit 33, the transmission / reception determination unit 34 selects one of the readers 10a and 10b as a reader to be transmitted to the tag 24. The transmission / reception control unit 35 transmits a control signal to each reader 10a, 10b based on the output of the data processing unit 32 and the output of the transmission / reception determination unit 34.

The operation of the control device 3 in the first embodiment will be described with reference to the flowchart shown in FIG. In this example, the reader 10b sends the data of the signal S2 received from the tag 24 to the receiving unit 31 of the control device 3, and this is received by the receiving unit 31 (step ST101). On the other hand, the reader 10a sends to the receiving unit 31 of the control device 3 that the signal S2 from the tag 24 has not been received, and this is received by the receiving unit 31 (step ST101). Here, as a method of determining that the signal S2 could not be received, for example, when the readers 10a and 10b cannot receive the signal S2 even after a predetermined time has elapsed after transmitting the signal S1, the signal S2 Is not received.
The receiving unit 31 of the control device 3 sends the data received from the reader 10b to the data processing unit 32 (step ST102). The data processing unit 32 processes the data received from the receiving unit 31 (step ST103). Here, in the present configuration example, the reader 10b is the only reader that has received the signal S2 from the tag 24. However, when the signal S2 is received by a plurality of readers, each signal is sent to the data processing unit 32, and the data processing unit In 32, processing such as discarding the same data is performed.

  In addition, the reception unit 31 sends the reception result of the signal S2 of the readers 10a and 10b to the reception status storage unit 33 (step ST104). The reception status storage unit 33 stores the reception status of signals from the tags 24 of the readers 10a and 10b connected to the control device 3 (step ST105), and transmits the reception status to the transmission / reception determination unit 34 (step ST105). ST106). Based on the reception status of each reader sent from the reception status storage unit 33, the transmission / reception determination unit 34 determines a reader that transmits the next signal and a reader that performs only reception without transmitting a signal (steps ST107 to ST107). ST109). The processes in steps ST107 to ST109 are repeated for each reader. When the reader receives a signal from the tag, the reader is determined to transmit the next signal (Y in step ST107). From step ST108), if the signal from the tag is not received, the next signal is not transmitted and the reader is determined to receive only (from step N to step ST109 in step ST107). However, in step ST108, when signals are received by a plurality of readers, processing for selecting one of them is also performed.

  When the transmission / reception determining unit 34 determines a reader that transmits the next signal, when a plurality of readers receive a signal from the tag 24, the plurality of readers can be candidates for transmitting the next signal. The method of selecting one reader from the above is not particularly limited (for example, the reader having the highest signal strength of the signal received from the tag 24 is selected, the priority is given to each reader, or the reader is randomly selected). In the present configuration example, the reader 10b is the only reader that has received the signal from the tag 24. Therefore, the reader 10b is selected as the reader that transmits the next signal S3, and the reader 10a is determined to be the reader that only receives the signal. The determination result in the transmission / reception determination unit 34 is sent to the transmission / reception control unit 35.

  Based on the result of the transmission / reception determination unit 34, the transmission / reception control unit 35 sends instructions for transmission and reception of the next signal to each reader. In the present configuration example, the transmission / reception control unit 35 instructs the reader 10a to only receive the signal S4 from the tag 24, and transmits the next signal S3 and the signal S4 from the tag 24 to the reader 10b. Give instructions. At that time, the content of the next signal S3 transmitted by the reader 10b is sent from the data processing unit 32 to the transmission / reception control unit 35 (step ST110) and notified to each reader 10a, 10b (step S111). Therefore, since the reader 10a that does not transmit the signal S3 can also recognize that the signal S4 is transmitted from the tag 24, the signal S4 from the tag 24 can be received.

  As described above, by controlling the transmission / reception between the readers 10a and 10b by the control device 3, the data reading rate of both the readers 10a and 10b and the tag 24 can be improved. Therefore, it is possible to improve the data reading rate of the entire system.

[Embodiment 2]
FIG. 4 shows a configuration example of the second embodiment of the present invention. In the first embodiment, the configuration example in which the signal of the response from the tag to the signal from the reader is completed by one data reception is shown. However, in the present embodiment, the response signal from the tag is a plurality of continuous data. This is a corresponding configuration example. 4A is a system configuration diagram, and FIG. 4B is a sequence diagram of communication operations. The RFID system according to the present embodiment includes a plurality of readers 10a, 10b, and 10c capable of transmitting and receiving signals to and from the tag 25, and a control device 3a for establishing cooperation between the readers 10a, 10b, and 10c. Has been. In the RFID system according to the present embodiment, the reader 10a, the reader 10b, and the reader 10c are connected to the control device 3a by a wired or wireless communication line (or control line) and controlled by the control device 3a. In this configuration, the reader 10a, the reader 10b, and the reader 10c are controlled so that one reader transmits a signal and the other readers only receive based on an instruction from the control device 3a. In addition, the control device 3 a performs control so that one of the readers that has received the signal from the tag 25 transmits the next signal to the tag 25.

  In FIG. 4, the reader 10 a transmits a signal S <b> 1 to the tag 25. As in the first embodiment, the reader 10b and the reader 10c are controlled to perform only reception by the control device 3a. In response to the signal S1 from the reader 10a, the tag 25 transmits a continuous signal S2 and signal S3. When the signal S2 is received by the reader 10b and the signal S3 is received by the reader 10c, the signal S2 and the signal S3 are sent to the control device 3a and synthesized by the control device 3a to become one data. That is, in the RFID system according to the present embodiment, when the signals S2 and S3 transmitted from the tag 25 are distributed and received by the plurality of readers 10b and 10c, the signals received by the control device 3a are distributed. S2 and S3 are synthesized.

  The configuration and flowchart of the control device 3a are the same as those in FIGS. 2 and 3, and the difference from the first embodiment is that when the data processing unit processes the data processing, a plurality of data from different readers are combined into one. It is a point to do. As a result, data can be synthesized if a signal transmitted continuously from the tag 25 can be received by any one of the readers, so that the data reading rate of the reader can be improved.

  A method of connecting a plurality of antennas to one reader and combining the data received by each antenna is also conceivable. However, in this case, the processing load increases because it is necessary to perform data combining processing with one reader. Resulting in. On the other hand, in the present invention, since the data composition processing is processed by the control device 3a connected to the reader, there is an advantage that the processing load on the reader does not increase.

[Embodiment 3]
FIG. 5 shows a configuration example of Embodiment 3 of the present invention. In the first embodiment, the configuration example in which the signal of the response from the tag to the signal from the reader is completed by one data reception is shown. In the second embodiment, a configuration example in which data with continuous tags is continuously transmitted in response to a signal from the reader has been described. In the present embodiment, the response signal from the tag to the signal from the reader is not completed in one data reception, but the response signal to the signal from the reader is repeatedly transmitted a plurality of times, and finally This is a configuration corresponding to the case where the data received by the reader is combined.

  5A is a system configuration diagram, and FIG. 5B is a communication operation sequence diagram. The RFID system according to the present embodiment includes a plurality of readers 10a, 10b, and 10c capable of transmitting and receiving signals to and from the tag 26, and a control device 3b for establishing cooperation between the readers 10a, 10b, and 10c. Has been. In the RFID system according to the present embodiment, the reader 10a, the reader 10b, and the reader 10c are connected to the control device 3b via a wired or wireless communication line (or control line) and controlled by the control device 3b. In this configuration, the reader 10a, the reader 10b, and the reader 10c are controlled so that one reader transmits a signal and the other readers only receive based on an instruction from the control device 3b. Further, the control device 3b performs control such that one of the readers that has received the signal from the tag 26 transmits the next signal to the tag 26.

  In FIG. 5, first, the tag 26 transmits a signal S2 in response to the signal S1 from the reader 10a. The reader 10a and the reader 10c fail to receive, but if the reader 10b succeeds in receiving, the reader 10b transmits the next signal S3 to the tag 26 as in the first embodiment. On the other hand, it is assumed that the tag 26 transmits the signal S4, the reader 10a and the reader 10b fail to receive, and the reader 10c succeeds in receiving. Here, the control device 3b combines the signal S2 successfully received by the reader 10b and the signal S4 successfully received by the reader 10c. The configuration and flowchart of the control device 3b are the same as those in FIGS. 2 and 3, and the difference from the first and second embodiments is that a plurality of data including the data received in the past is combined when the data is processed by the data processing unit. It is a point to do. That is, in this embodiment, when a signal is continuously transmitted / received a plurality of times to / from the tag 26, the reader that transmits a signal to the tag 26 is sent to the tag 26 once by the control device 3 b. In addition to selecting each time, the signals received by a plurality of readers in a plurality of times are combined.

  As a result, data can be synthesized if any one of the readers can receive a signal transmitted in a plurality of times from the tag, so that the reading rate of the reader can be improved. Further, as in the second embodiment, the data composition processing is performed by the control device 3b connected to the reader, and therefore there is an advantage that the processing load on the reader does not increase.

  As described above, according to the present invention, when a plurality of readers are used and a certain reader transmits a signal, the other reader controls only reception of the signal, and a tag for a signal transmitted by a certain reader is used. Even if the reader that sent the signal has moved to an area where it cannot communicate with the tag by controlling not only the reader that sent the response signal from other readers but also other readers, By receiving this, it is possible to improve the data reading rate of the entire system. Furthermore, by controlling the reader that receives the signal from the tag to transmit the next signal, the data reading rate of the tag can be improved. When the reader or tag moves at a high speed, the communication environment changes greatly, and the combination of the reader and tag with good communication conditions always changes. On the other hand, according to the present invention, it is possible to select a reader and a tag with the best communication status from time to time depending on whether or not a signal from the tag is received. The rate can be improved.

  In this way, by using the passive RFID system of the present invention, even when the tag or reader is moving at high speed (for example, about several tens of kilometers per hour), the entire system can be obtained by using a plurality of readers. The data reading rate can be improved, and communication is possible even when moving at high speed.

  The embodiment of the present invention is not limited to the above. For example, the number of readers is four or more, the number of control devices is two or more, or a plurality of control devices are arranged between them. A connection form having a structure, or the configuration in the control device 3 shown in FIG. 2 is further divided or integrated into a plurality of functional blocks, or each functional block is distributed and arranged via a communication line, etc. It is possible to make changes. The control device according to the present invention can be realized by a computer and a program, and the program can be recorded on a recording medium or provided through a network.

1A and 1B are a system diagram (a) and a sequence diagram (b) illustrating a configuration and a signal flow of an RFID system according to a first embodiment of the present invention. It is a block diagram which shows the structural example of the control apparatus 3 shown in FIG. It is a flowchart which shows operation | movement of the control apparatus 3 shown in FIG. It is the system figure (a) and sequence diagram (b) which show the structure and signal flow of Embodiment 2 of the RFID system of this invention. It is the system figure (a) and sequence diagram (b) which show the structure and signal flow of Embodiment 3 of the RFID system of this invention. BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows an example of the RFID system for demonstrating the background art of this invention, and is a system diagram (a) and a sequence diagram (b) which show the structure and signal flow of an RFID system. It is another figure which shows an example of the RFID system for demonstrating the background art of this invention, and is a system diagram (a) and a sequence diagram (b) which show the structure and signal flow of an RFID system. It is another figure which shows an example of the RFID system for demonstrating the background art of this invention, and is a system diagram (a) and a sequence diagram (b) which show the structure and signal flow of an RFID system. It is another figure which shows an example of the RFID system for demonstrating the background art of this invention, and is a system diagram (a) and a sequence diagram (b) which show the structure and signal flow of an RFID system. It is another figure which shows an example of the RFID system for demonstrating the background art of this invention, and is a system diagram (a) and a sequence diagram (b) which show the structure and signal flow of an RFID system.

Explanation of symbols

10a, 10b, 10c ... Reader 3, 3a, 3b ... Control device 24, 25, 26 ... Tag (passive RFID tag)
S1, S2, S3, S4 ... signal

Claims (10)

In an RFID system using a plurality of passive RFID tags,
A plurality of readers capable of transmitting and receiving signals to and from a passive RFID tag;
A controller for coordinating between the readers,
By the control device,
When any one of the plurality of readers transmits a signal, the other reader performs control to only receive the signal,
An RFID system, wherein one of the plurality of readers that has received a signal from the passive RFID tag performs control to transmit a next signal to the passive RFID tag. When the signals transmitted from any one of the plurality of passive RFID tags are received by the plurality of readers, the control device synthesizes the signals received by the plurality of readers. The RFID system according to claim 1. When transmitting / receiving a signal a plurality of times continuously between any one of the plurality of passive RFID tags and the plurality of readers,
By the control device,
Selecting a reader that transmits signals from the plurality of readers to the passive RFID tag for each of a plurality of transmissions;
The RFID system according to claim 1, wherein one or a plurality of readers synthesize the signals received a plurality of times. In an RFID system using a plurality of passive RFID tags,
A plurality of readers capable of transmitting and receiving signals to and from a passive RFID tag;
Using a control device for cooperation between the readers,
By the control device,
When any one of the plurality of readers transmits a signal, the other reader performs control so as to only receive the signal,
A method for controlling an RFID system, wherein one of the plurality of readers that has received a signal from the passive RFID tag performs control to transmit a next signal to the passive RFID tag. When the signals transmitted from any one of the plurality of passive RFID tags are received by the plurality of readers, the control device synthesizes the signals received by the plurality of readers. The method of controlling an RFID system according to claim 4. When transmitting / receiving a signal a plurality of times continuously between any one of the plurality of passive RFID tags and the plurality of readers,
By the control device,
Selecting a reader that transmits signals from the plurality of readers to the passive RFID tag for each of a plurality of transmissions;
The RFID system control method according to claim 4, wherein the signals received by the one or more readers are combined a plurality of times. In an RFID system using a plurality of passive RFID tags and a plurality of readers capable of transmitting and receiving signals between the plurality of passive RFID tags,
A control device for coordinating between the plurality of readers,
When any one of the plurality of readers transmits a signal to the passive RFID, the other reader performs control to only receive the signal,
A control apparatus in an RFID system, wherein one of the plurality of readers that has received a signal from the passive RFID tag performs control to transmit a next signal to the passive RFID tag. When the plurality of readers receive a signal transmitted from any one of the plurality of passive RFID tags, the control device synthesizes the signals received by the plurality of readers. 8. The control device in the RFID system according to claim 7, When the control device performs continuous transmission and reception of signals a plurality of times between any one of the plurality of passive RFID tags and the plurality of readers,
Selecting a reader that transmits signals from the plurality of readers to the passive RFID tag for each of a plurality of transmissions;
The control apparatus in the RFID system according to claim 7, wherein the signals received by the one or more readers are combined a plurality of times. The control device according to claim 7 is configured using a computer, and when one of the plurality of readers transmits a signal in the computer, the other reader A program for performing only reception, and for controlling one of the plurality of readers that has received a signal from the passive RFID tag to transmit the next signal to the passive RFID tag. .

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