JP3742045B2 - Wireless tag and telemetry system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a telemetry system that reads and manages the state of an article or person, and in particular, a telemetry system that transfers sensor data obtained from an article or person to a host device using a wireless tag, and the telemetry system thereof The present invention relates to a wireless tag suitable for use.
[0002]
[Prior art]
The wireless tag is an electronic tag (tag) in which an IC chip and an antenna are embedded, and can identify and control an attached article or person wirelessly. For example, in a logistics management system that collects and delivers packages, when a package moving on a belt conveyor is loaded on a delivery truck, the logistics management system uses an antenna and an interrogator to attach a wireless tag attached to the package. The delivery destination is read from, and the belt conveyor is switched so that it can be mounted on the delivery truck.
[0003]
In such a system using a wireless tag, when there are a plurality of wireless tags in the communication area of the antenna, all the wireless tags send a reply signal to the transmission signal from the interrogator. There is a problem that the interrogator cannot identify the wireless tag. As a conventional technique capable of preventing interference between a plurality of wireless tags and an interrogator and identifying each wireless tag, there is an identification method described in WO 98/21691.
[0004]
In this identification method, the interrogator and the plurality of wireless tags operate as follows. Each wireless tag returns each identification bit in response to the question command of the interrogator. The interrogator transmits many received identification bits as ID bits to the wireless tag. Each wireless tag returns the next identification bit when the received ID bit and the returned identification bit are equal. When the received ID bit is not equal to the returned identification bit, the wireless tag does not participate in the remaining identification processing and does not respond until the interrogator issues a question command again. By repeating this process, only one wireless tag is finally identified. The wireless tag once identified does not participate in the identification process until an initialization command is received from the interrogator. By repeating this identification process, all wireless tags can be identified.
[0005]
As described above, in the conventional technology, the identification bit received by the interrogator is sent to the wireless tag as an ID bit, so that each wireless tag is determined to participate in the identification process, and finally one wireless tag is identified. be able to. Moreover, since the wireless tag once identified does not return a reply until the initialization command is received from the interrogator, the interference between the interrogator and the wireless tag is reduced, and the communication state is improved.
[0006]
[Problems to be solved by the invention]
When managing goods and people, it is important to monitor not only the identification but also the state of the goods and people. By using conventional technology, even if there are many articles or people with wireless tags in the communication area of the antenna, each article or person can be identified. = Sensor data) cannot be stored, it is difficult to monitor articles and people.
[0007]
Telemetry systems have been used to monitor distant items and people. In the telemetry system, for example, when transmitting human biological data such as blood pressure and pulse to a host device, a sensor device that stores blood pressure sensor and pulse sensor data and a wireless device that transmits the stored sensor data to the host device have been used. It was. However, in a telemetry system using a radio device, it is necessary to change the frequency assigned by the article or person, and it is difficult to monitor a large number of articles or persons.
[0008]
In the conventional technique, since the wireless tag is selected based on the identification bit received by the interrogator, the communication start time with the interrogator varies depending on the ID bit of the wireless tag. When sensor data can be stored in the wireless tag, communication with the interrogator cannot be started, so that the sensor data of the wireless tag becomes full, and the sensor data received by the interrogator may be lost. In addition, the wireless tag that has been subjected to the sorting process will not return a reply until the initialization command is received from the interrogator. However, if the sensor data can be stored in the wireless tag, the wireless tag will not receive a reply until the initialization command is received. The sensor data of the tag becomes full, and sensor data received by the interrogator may be lost.
[0009]
An object of the present invention is to provide a telemetry system and a radio tag that do not require allocation frequency management.
Another object of the present invention is to propose a telemetry system and a radio tag that start communication with an interrogator before the sensor data in the radio tag is full and do not lose sensor data.
[0010]
[Means for Solving the Problems]
The wireless tag of the present invention that achieves the above object includes an antenna, a modulation / demodulation unit that performs modulation / demodulation processing for transmitting and receiving signals via the antenna, a non-volatile memory that includes an identification area that stores an identification code and a data area that stores data , A tag control unit that controls reading and writing of data to and from a nonvolatile memory, and a sensor that converts an input signal from a connected external sensor into sensor data under the control of the tag control unit and sends the sensor data to the tag control unit And a control unit.
The identification area can be used to store an invariant identification code for identifying each wireless tag and variable information indicating the communication priority.
[0011]
The wireless tag includes a communication priority setting unit, and the communication priority setting unit generates information indicating the communication priority based on the amount of sensor data stored in the data area of the nonvolatile memory, and Information may be written in a part of the identification area. The communication priority setting unit generates and generates a priority bit representing a communication priority based on the usage rate of the sensor data area calculated from the capacity of the data area and the amount of sensor data stored in the data area. The priority bit is written before the identification code of the identification area.
[0012]
The tag control unit transmits the first bit of the identification area of the non-volatile memory when receiving a question command from the interrogator while waiting for a question command, and then identifies if the received bit and the transmission bit received from the interrogator match. The next bit of the area is transmitted, and if it does not match, control to return to the question command waiting state can be performed.
The wireless tag may include a communication control initialization unit having a function of initializing a control state in the wireless tag when the amount of sensor data stored in the data area of the nonvolatile memory exceeds a set value. .
[0013]
A telemetry system according to the present invention includes an interrogator and a plurality of wireless tags connected to different sensors, respectively. In the telemetry system that individually retrieves data of each sensor via the interrogator, the wireless tag includes a tag antenna and A modulation / demodulation unit that performs modulation / demodulation processing for transmitting / receiving a signal via a tag antenna, a non-volatile memory having an identification area for storing an identification code for identifying the wireless tag, and a data area for storing data; A tag control unit that controls reading and writing of data to and from the memory, and a sensor control unit that converts an input signal from the connected sensor into sensor data under the control of the tag control unit and sends the sensor data to the tag control unit. The device performs an antenna for communicating with the wireless tag and a modulation / demodulation process for transmitting and receiving signals via the antenna. A modulation / demodulation unit, a memory for storing received data, a transmission unit that transmits a command to the wireless tag, a reception unit that analyzes a reception signal from the wireless tag, and a control unit that controls the operation of each unit, Processing for transmitting a question command from the interrogator to a plurality of wireless tags, processing for transmitting a first bit of each identification area by the wireless tag that has received the question command, the received bit or one of the received bits Processing for transmitting to a plurality of wireless tags, processing of the wireless tag that returns the next bit of the identification area if the received bit matches the previously transmitted bit, and returns to the question command waiting state if the bit does not match, An identification process for identifying one wireless tag is performed, and a sensor data reading process is performed for the identified one wireless tag.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings. In the following drawings, equivalent functional parts are denoted by the same reference numerals, and redundant description is omitted.
FIG. 1 is an overall schematic diagram showing an example of a telemetry system according to the present invention. Here, a medical telemetry system that attaches sensors and wireless tags to a plurality of patients and collects patient biometric data will be described as an example.
[0015]
This telemetry system includes sensors 6a to 6d that detect the states of patients 4a to 4c, wireless tags 5a to 5d that are connected to the sensors 6a to 6d and store sensor data, and questions that communicate with the wireless tags 5a to 5d through the antenna 3 A machine 1 is provided. Sensor data of the sensors 6 a to 6 d received by the interrogator 1 is transmitted from the interrogator 1 to the control device 2.
[0016]
FIG. 2 is a block diagram illustrating a configuration example of a wireless tag according to the present invention. The wireless tag 5 converts an antenna 21 used when communicating with the interrogator 1, a tag control circuit 23 that controls the entire wireless tag 5, and a signal from the sensor 6 into numerical data, and performs tag control on the converted sensor data. The sensor control circuit 24 to be sent to the circuit 23, the nonvolatile memory 20 such as EEPROM that stores the ID and sensor data that is the identification data of the wireless tag 5 under the control of the tag control circuit, and the tag antenna 21 received from the interrogator 1. A tag modulation / demodulation circuit 22 is provided for performing demodulation in order to demodulate received data from the high-frequency signal and transmit it to the tag control circuit 23 or to transmit data from the tag control circuit 23 to the interrogator 1. As described above, the wireless tag 5 is connected to the external sensor 6 and has a function of capturing sensor data from the sensor 6 and transmitting it to the interrogator.
[0017]
FIG. 3 is a block diagram illustrating a configuration example of the interrogator. The interrogator 1 stores the antenna 3 used to communicate with the wireless tag 5, the CPU 33 that controls the entire interrogator, the sensor data received from the wireless tag 5 under the control of the CPU 33, and the ID of the wireless tag 5. A transmission circuit 32 that transmits a command to the wireless tag 5 under the control of the memory 34 and the CPU 33, a reception circuit 35 that detects “1” or “0” from the signal received from the wireless tag 5, and transmits the result to the CPU 33, and a transmission circuit 32 A modulation / demodulation circuit 31 is provided that modulates a transmission command from the wireless tag 5 and transmits the modulated command to the antenna 3 and demodulates received data from the wireless tag 5 and transmits the data to the reception circuit 35.
[0018]
The wireless tag 5 and the interrogator 1 communicate by allowing the wireless tag 5 to interpret a command from the interrogator 1 and returning a response to the command. FIG. 4 shows a list of commands (commands) of the interrogator 1. For example, command 1 is an initialization command that returns the congestion control protocol state to the initial state. Commands 2 to 7 are commands for congestion control. Command 7 is a question command, and identification of the wireless tag is started by this command. Similarly, command 8 is a data read command, and command 9 is a data write command.
[0019]
(1) Wireless tag identification (congestion control)
Congestion control in RFID tag identification according to the present invention will be described with reference to FIGS. First, the congestion control on the interrogator side will be described using the flowchart of FIG.
The interrogator 1 transmits a question command from the antenna 3 to the wireless tag in the cover area (S11). The wireless tag that has received the question command from the interrogator transmits an identification code unique to each wireless tag to the interrogator by 1 bit.
The interrogator detects the transmission signal from the wireless tag (S12). If the transmission signal from the wireless tag cannot be detected, it is considered that identification of all the wireless tags is completed, and the identification is finished (S20).
[0020]
When the interrogator detects a transmission signal from the wireless tag, it receives 1 bit of the identification code (S13) and returns the received bit toward the wireless tag (S14). The wireless tag receives the returned bit and transmits the next 1 bit of the identification code to the interrogator according to the flowchart of FIG. The interrogator checks whether the received bit is the last bit of the identification code by counting the number of received bits (the identification code length is set to a constant value in the system) (S15).
[0021]
If the received bit is not the last bit of the identification code, the interrogator checks whether there is transmission of the next bit from the wireless tag (S19). If a transmission signal is detected, 1 bit of the next identification code transmitted from the wireless tag is received (S13). On the other hand, if the transmission of the next bit cannot be detected, the question command is transmitted again as identification failure (S11).
[0022]
If the received identification code is the last bit, a CRC check is performed on all received bits (S16), and if there is an error, a question command is transmitted again (S11). On the other hand, if there is no error, it is determined that the identification code has been correctly received, and an identification completion signal is sent back to the wireless tag to notify the wireless tag that it has been received correctly (S17). The identification code of the identified wireless tag is output from the connection cable to the control device 2 (S18), and is repeated from the transmission of the question command again (S11).
Next, congestion control on the wireless tag side will be described using the flowchart of FIG.
[0023]
The tag control circuit 23 of the wireless tag 5 waits for a question command from the interrogator 1 (S21). When a question command from the interrogator is detected, the wireless tag transmits only one bit of the identification code (S22). The wireless tag checks whether there is one bit of the identification code returned by the interrogator (S23), and if not, returns to waiting for a question command (S21).
[0024]
When 1 bit of the identification code is received, it is compared with 1 bit of the identification code already transmitted (S24). If the received bit and the transmitted bit do not match, it is determined that the identification has failed, and the process returns to waiting for a question command (S21). If the received bit matches the transmitted bit, it is checked whether the bit is the last bit (S25). If it is not the last bit, the next bit is transmitted (S22). If it is the last bit, it waits for the transmission of the identification completion signal from the interrogator (S26). If the identification completion signal cannot be detected, the process returns to waiting for a question command (S21). If the identification completion signal is detected, it is determined that the identification is successful, and the identification operation is terminated (S27).
[0025]
FIG. 7 is a state transition diagram of the identification processing of the wireless tag 5. When the wireless tag 5 enters the irradiation area of the antenna 3 of the interrogator 1, power is supplied and a power-on reset is applied to the tag control circuit 23 of the wireless tag 5. This state is referred to as a state SR0. When the command 8 (ID / address designation read) is received in the state SR0, the state transits to the state SIR0 (FIG. 8). When the command 9 (ID / address designation write) is received, the state transits to the state SIW0 (FIG. 9). If a command other than commands 7, 8, and 9 is received in state SR0, it remains in state SR0.
[0026]
When the command 7 (question) is received in the state SR0, the value of the first 1 bit of the identification code is transmitted. This state is state SR1. The state SRk (k = 1 to n) is a state in which the identification code is read by k bits. The interrogator notifies the received value by command 2 (0 reply) and command 3 (1 reply). As described with reference to FIG. 6, if the 1-bit value transmitted in the state SRk corresponds to the command from the interrogator, the state SRk transitions to the state SRk + 1. When not corresponding, it changes to state SR0.
[0027]
When all bits have been transmitted (state SRn), the interrogator checks the CRC. When no error is detected, command 5 (data OK) is transmitted, and when an error is detected, command 6 (data NG) is transmitted. The wireless tag that has received the command 6 transitions to the state SR0 as an identification failure. The wireless tag that has received the command 5 transits to the state SRH as identification completion, and remains in the SRH until the command 1 (initialization) is received. Therefore, it will not participate in the identification process thereafter.
[0028]
(2) Data read processing
FIG. 8 is a state transition diagram of the ID / address designation read command. When a command 8 (ID / address designation read) is received in the state SR0, the state transits to the state SIR0. The interrogator transmits the data read address and CRC. A state where reception of all the data determined by the system is completed is a state SIR1.
[0029]
In the state SIR1, a CRC check is performed on the received data, and if there is an error, the flow goes to the state SR0, and if there is no error, the flow goes to the state SIR2. The interrogator sends a command 10 (1-bit data return command). The wireless tag in the state SIR2 returns data bit by bit from the specified address every time the command 10 is received. When a command other than the command 10 is received, the state transits to the state SR0.
[0030]
(3) Data writing process
FIG. 9 is a state transition diagram of the writing process to the nonvolatile memory of the wireless tag via the interrogator. When the command 9 (ID / address designation write) is received in the state SR0, the state transits to the state SIW0. The interrogator transmits the number of identification tag bytes, identification code, write address, and CRC of the wireless tag that is the target of the data write process. The state SIW1 is a state in which all data determined by the system has been received.
[0031]
In the state SIW1, a CRC check is performed on the received data, and if there is an error, transition is made to the state SR0, and if there is no error, transition is made to the state SIW2. The interrogator sends command 12 (write enable). When receiving the command 12 (write enable), the wireless tag in the state SIW2 makes the nonvolatile memory writable. This state is state SIW3. In the state SIW3, the writing process to the nonvolatile memory is started. In the state SIW3, when a command other than the command 11 (write status reply command) is received, the state transits to the state SIW4, the nonvolatile memory is set in the write disabled state, and the state transits to the state SR0.
[0032]
FIG. 10 is a diagram illustrating an example of a frame structure of reply data returned from the wireless tag to the interrogator. The reply data frame 40 returned from the wireless tag includes an identification area 41 indicating the identification of the wireless tag 5 and a sensor data area 42 subsequent thereto.
[0033]
FIG. 11 is a diagram illustrating an example of a memory map of the EEPROM 20 provided in the wireless tag. Tag identification information is stored in the identification area 111 at address 00H, and sensor data is stored in the sensor data area 112 after address 01H.
[0034]
FIG. 12 is a diagram illustrating a configuration example of a sensor control circuit in the wireless tag. The sensor control circuit 24 includes an A / D converter 1200 that converts the sensor signal from the sensor 6 into an analog-to-digital converter, an oscillator 1201 that generates a clock, and a clock of the oscillator 1201 based on a divided signal 1203 that is sent from the tag control circuit 23. 1 and a latch circuit 1202 for storing the analog-digital conversion result of the A / D converter 1200.
[0035]
SCLK is a signal indicating an interval for analog-digital conversion of the signal from the sensor 6. The AD start signal 1204 is a signal indicating the start of A / D conversion sent from the tag control circuit 23, and the capture permission signal 1206 is a signal indicating that the analog-digital conversion result is stored in the latch circuit 1202. is there.
[0036]
FIG. 13 is a diagram for explaining a procedure for storing sensor data. The sensor data is written without using a command.
When the AD start signal 1204 becomes H after the frequency-divided signal 1203 is generated (T0), SCLK starts to be transmitted, the analog value of the sensor signal 1209 is taken into the A / D converter 1200, and analog-digital conversion is started ( T1). When SCLK changes to L, the analog-digital conversion result of the sensor signal 1209 is stored in the latch circuit 1202 (T2). Next, when SCLK becomes H, the capture permission signal becomes H, and the sensor data 1205 is stored in the tag control circuit 23 (T3). These series of operations are continued until the AD start signal 1204 becomes L.
The tag control circuit 23 that has received the sensor data from the sensor control circuit 24 stores the sensor data in the EEPROM 20. FIG. 14 is a diagram for explaining an EEPROM access procedure.
[0037]
The tag control circuit 23 includes an access circuit to the EEPROM 20. As shown in the figure, in the tag control circuit 23, a command control circuit 1400 for interpreting and executing a command sent from the interrogator 1, an address for reading sensor data from the EEPROM 20, and a read clock 94 are stored. The read counter 1401 to be counted up, the address for writing sensor data to the EEPROM 20 are stored, the write counter 1402 to be counted up by the write clock 93, and the select signal 1406 of the command control circuit 1400 to read the read counter 1401 or the write counter 1402 Is provided as an EEPROM address 1407 to the EEPROM 20, and an EEPROM data bus 1410 is provided for use when reading or writing sensor data from the EEPROM 20.
[0038]
When writing the sensor data received from the sensor control circuit 24 to the EEPROM 20, the command control circuit 1400 outputs the write counter 1402 to the EEPROM 20 as the EEPROM address 1407 using the selector 1403. Further, the command control circuit 1400 outputs the sensor data to the EEPROM 20 via the EEPROM data bus 1410. Next, the command control circuit 1400 outputs the write clock 93 to the EEPROM 20 and writes the sensor data in the area indicated by the EEPROM address 1407 of the EEPROM 20. At this time, the write counter is counted up.
[0039]
When reading the sensor data from the EEPROM 20, the command control circuit 1400 outputs the read counter 1401 to the EEPROM 20 as the EEPROM address 1407 using the selector 1403. Next, the command control circuit 1400 outputs the read clock 94 to the EEPROM 20 and reads the sensor data from the area indicated by the EEPROM address 1407 of the EEPROM 20. The read counter 1401 and the write counter 1402 have a loop structure that returns to the minimum value when the maximum count value is exceeded and counts up again. For this reason, the sensor data storage area of the EEPROM 20 has a loop structure.
[0040]
FIG. 15 is a diagram illustrating a procedure of selecting one wireless tag from wireless tags having a plurality of interrogators and transferring sensor data from the selected wireless tag to the interrogator.
For example, when the interrogator 1 identifies one radio tag from the radio tags 5 a, 5 b, and 5 d existing in the communication area of the antenna 3 and receives sensor data, the interrogator 1 is connected to the communication area via the antenna 3. The "question command" is transmitted to the wireless tags 5a, 5b, 5d in (10). The wireless tag 5a, the wireless tag 5d, and the wireless tag 5b that have received the “question command” from the interrogator 1 return the bit 1 of the ID at the address 00H in each EEPROM 20, respectively. In this case, the wireless tag 5a returns “1” (T11), the wireless tag 5d returns “1” (T12), and the wireless tag 5b returns “0” (T13). The interrogator 1 receives “0” and “1” at the same time. When the interrogator 1 receives “0” and “1” at the same time, priority is given to “1” in this example.
[0041]
The interrogator 1 transmits a “1 confirmation command” to the wireless tag (T14). When the wireless tag receives a confirmation command having the same value as the ID returned by itself, the wireless tag returns the next ID bit. In the example shown in the figure, the wireless tags 5a and 5d return “1” (T15), and the wireless tag 5d returns “0” (T16). The wireless tag 5b does not return a response to the interrogator 1 until the next “question command” is received. Since the interrogator 1 receives “0” and “1” at the same time, it transmits a “1 confirmation command” (T17). The wireless tag 5a that has received the “1 confirmation command” returns “0” (T18). The wireless tag 5d does not reply to the interrogator. The interrogator 1 transmits a “1 confirmation command” or a “0 confirmation command” to the received value even if the wireless tag 5 that is returned is only the wireless tag 5a (T19). The wireless tag 5a returns the sensor data stored after the address 01H in the EEPROM to the interrogator 1 (T20).
[0042]
Thus, in the telemetry system of this example, the sensor control circuit 24 is provided in the wireless tag 5, and the biological data of the patient 4 is obtained using the sensors 6a, 6b, 6c,... Attached to the patients 4a, 4b, 4c. Are stored in a plurality of wireless tags 5 a, 5 b, 5 c,..., And in response to a request from the interrogator 1, a plurality of sensor data of each patient is returned to the interrogator 1 in an identifiable form.
[0043]
As described above, the telemetry system using the wireless tag shown in FIG. 2 includes a sensor control circuit in the wireless tag, stores the patient's biological data in the wireless tag using the sensor attached to the patient, Since the sensor data of the patient is returned to the interrogator upon request, not only the recognition of the patient wearing the wireless tag, which is a conventional technique, but also the patient state can be monitored in real time.
[0044]
In this example, a medical telemetry system that attaches a sensor and a wireless tag to a patient and collects biometric data is used in the description. However, the target to which the sensor and the wireless tag are attached is not limited to the patient. The present invention can be applied to a logistics management system in which a temperature sensor and a wireless tag are attached to constantly monitor the temperature of the luggage, or a library management system in which a humidity sensor is attached to a library book to monitor a storage state.
[0045]
FIG. 16 is a diagram showing another configuration example of the wireless tag of the present invention used in the telemetry system. The configuration of the telemetry system is the same as that shown in FIG. The wireless tag 5 includes a priority bit setting circuit 60 that generates a priority bit in the tag control circuit 23 based on the amount of sensor data stored in the EEPROM 20 and sets a priority bit string in the tag control circuit 23.
[0046]
FIG. 17 is a diagram illustrating a configuration example of the priority bit setting circuit. The priority bit setting circuit 60 shown includes a sensor data counter 90, a sensor data capacity register 91, and a priority bit generation circuit 92. The sensor data capacity register 91 stores the sensor data capacity in the EEPROM 20. The write clock 93 is a clock for writing sensor data to the EEPROM 20, and the read clock 94 is a clock for reading sensor data from the EEPROM 20, which has been described with reference to FIG. The sensor data counter 90 is a counter whose value increases with the sensor data write clock 93 and decreases with the sensor data read clock 94. The priority bit generation circuit 92 generates a priority bit 95 based on the value of the sensor data counter 90 and the value of the sensor data capacity register 91.
[0047]
For example, when 1 byte of sensor data is written in the EEPROM 20, the write counter 1402 in the tag control circuit 23 shown in FIG. 14 counts up, and the sensor data counter 90 also counts up. When sensor data is read from the EEPROM 20 by 1 byte, the read counter 1401 in the tag control circuit 23 counts up and the sensor data counter 90 counts down. As described above, the sensor data counter 90 indicates how many bytes of sensor data exist in the EEPROM 20.
[0048]
FIG. 18 is a diagram for explaining a priority bit setting table used in the priority bit generation circuit. Using this priority bit setting table, the priority bit generation circuit 92 generates “1111” as a priority bit when, for example, the usage rate of the sensor data area is 80% or more, and when it is 75% or more and less than 80%, “ When “1110” is 5% or more and less than 10%, “0001” is generated. The sensor data area usage rate is calculated by dividing the value of the sensor data counter 90 by the value of the sensor data capacity register 91.
[0049]
FIG. 19 is a diagram showing an example of the structure of a reply frame sent back to the interrogator by the wireless tag 5 shown in FIG. This frame 40 has a priority bit area 80 for returning priority bits 95, an identification area 41 for returning identification information of the wireless tag following the priority bit area 80, and a sensor data area 42.
[0050]
FIG. 20 is a diagram for explaining the operation of writing the priority bit to the EEPROM in the wireless tag.
For example, when the sensor data is returned from the wireless tag 5 to the interrogator 1, the wireless tag 5 confirms whether or not the “question command” is received from the interrogator 1 (S31). When the “question command” is received, the wireless tag 5 performs wireless tag identification processing with the interrogator 1 (S37). If the wireless tag 5 is not selected, it waits for the “question command” from the interrogator 1 again. If selected (S38), the tag control circuit 23 reads the sensor data from the EEPROM 20 (S39). The sensor data is transmitted to the machine 1 (S40). At this time, the sensor data counter 90 is subtracted by the number of times the sensor data read signal is generated (S41). When the “question command” is not received from the interrogator 1 (S31), the sensor control circuit 24 A / D converts the signal from the sensor 6 to generate sensor data (S32). The tag control circuit 23 writes the sensor data in the EEPROM 20 (S33). At this time, the sensor data counter 90 is incremented by the number of times the sensor data write signal 93 is generated (S34). When the value of the EEPROM 20 is changed, the priority bit generation circuit 92 generates the priority bit 95 (S35), and the tag control circuit 23 writes the priority bit 95 to the EEPROM 20 (S36).
[0051]
FIG. 21 is a diagram illustrating a procedure for selecting one wireless tag from wireless tags having a plurality of interrogators and transferring sensor data from the wireless tag to the interrogator.
For example, when the interrogator 1 identifies one of the wireless tags 5 a, 5 b, 5 d existing in the communication area of the antenna 3 and receives sensor data, the interrogator 1 is in the communication area via the antenna 3. A “question command” is transmitted to the wireless tags 5a, 5b, 5d (T20). When the “question command” is received from the interrogator 1, the wireless tag 5a has a sensor data area usage rate of 60%, the wireless tag 5d has a sensor data area usage rate of 70%, and the wireless tag 5b has a sensor data area usage rate. Suppose that it was 40%. The wireless tag 5a, the wireless tag 5d, and the wireless tag 5b that have received the “question command” from the interrogator 1 return bit 1 of the priority bit area 80, respectively. In this case, the wireless tag 5a returns “1” (T21), the wireless tag 5d returns “1” (T22), and the wireless tag 5b returns “0” (T23). The interrogator 1 receives “0” and “1” at the same time. In the case of this example, when the interrogator 1 receives “0” and “1” at the same time, “1” has priority. The interrogator 1 transmits a “1 confirmation command” to the wireless tag (T24). When the wireless tag receives a confirmation command having the same value as the ID returned by itself, the wireless tag returns the next ID bit. In this case, the wireless tag 5a returns the value “0” of bit 2 of the priority bit area 80 (T25), and the wireless tag 5d returns “1” (T26). The wireless tag 5b does not return a response to the interrogator 1 until the next “question command” is received.
[0052]
Since the interrogator 1 receives “0” and “1” at the same time, it transmits a “1 confirmation command” (T27). The wireless tag 5d that has received the “1 confirmation command” returns the value “0” of bit 3 in the priority bit area 80 (T28). The wireless tag 5a does not reply to the interrogator. The interrogator 1 returns only the wireless tag 5d as the wireless tag 5 that replies. And However, a “1 confirmation command” or a “0 confirmation command” is transmitted for the received value (T29). The wireless tag 5d returns the sensor data stored after the address 01H in the EEPROM to the interrogator 1 (T30).
[0053]
As described above, in the telemetry system of this example, the priority bit setting circuit 60 is provided in the wireless tag 5 so that the priority bit 95 is generated according to the usage rate of the sensor data storage area and returned to the interrogator. The wireless tag having a high usage rate in the sensor data storage area is preferentially selected by the interrogator. By using a wireless tag having a priority bit setting circuit in this way, it is possible to prevent the generation of sensor data that cannot be stored in the nonvolatile memory of the wireless tag. The application of the telemetry system of this example is not limited to the medical telemetry system.
[0054]
FIG. 22 is a diagram showing another configuration example of the wireless tag of the present invention used in the telemetry system. The configuration of the telemetry system is the same as that shown in FIG.
In the wireless tag 5, the tag control circuit 23 includes a no-response cancellation circuit 140 that cancels the no-response state of the wireless tag 5. Once communication with the interrogator 1 is completed, the wireless tag 5 shifts to a no-response mode in order to avoid interference between the interrogator 1 and another wireless tag 5, and receives an “initialization command” from the interrogator 1. A reply is not returned to the “question command” from the interrogator 1 until it is received.
[0055]
FIG. 23 is a diagram illustrating a configuration example of the no-response cancellation circuit 140. The no-response cancellation circuit 140 includes a sensor data counter 90 indicating how many bytes of sensor data are present in the EEPROM 20, a no-response cancellation value register 142 that sets a sensor data storage capacity that requires no-response cancellation, and a comparator. 143. The comparator 143 compares the sensor data counter 90 and the no-response release value register 142 and generates a no-response release signal 141. The no-response release signal resets the tag control circuit.
[0056]
FIG. 24 is a diagram for explaining the operation in which the no-response cancellation signal 141 is generated. For example, when the sensor data is returned from the wireless tag 5 to the interrogator 1, the wireless tag 5 confirms whether or not the “question command” is received from the interrogator 1 (S51). If the wireless tag 5 is in the non-response state when the “question command” is received, it waits for the “question command” from the interrogator 1 again. If the wireless tag 5 is not in the non-response state (S57), the wireless tag 5 The wireless tag identification process is performed between the two (S58). If the wireless tag 5 is not selected, it waits for the “question command” from the interrogator 1 again. If selected (S59), the tag control circuit 23 reads the sensor data from the EEPROM 20 (S60). The sensor data is transmitted to the machine 1 (S61). At this time, the sensor data counter 90 is decremented by the number of times the sensor data read signal is generated (S62), and the wireless tag 5 shifts to a non-response state until receiving an “initialization command” from the interrogator 1 (S63). .
[0057]
When the “question command” is not received from the interrogator 1 (S51), the sensor control circuit 24 digitizes the state of the sensor 6 and generates sensor data (S52). The tag control circuit 23 writes the sensor data in the EEPROM 20 (S53). At this time, the sensor data counter 90 is incremented by the number of times the sensor data write signal 93 is generated (S54). When there is a change in the value of the EEPROM 20, the comparator 143 determines whether or not the value of the sensor data counter 90 exceeds the value of the no-response cancellation value register 142 (S55). A cancel signal 141 is generated to shift the wireless tag 5 from the no-response state to the response state (S56).
[0058]
FIG. 25 shows a procedure for selecting one wireless tag from wireless tags having a plurality of interrogators and transferring sensor data from the selected wireless tag to the interrogator in the telemetry system using the wireless tags shown in FIG. FIG.
Now, it is assumed that the wireless tag 5d finishes the sensor data transfer to the interrogator 1 and is in a no-response state (T40). When the interrogator 1 identifies one of the plurality of wireless tags 5 existing in the communication area of the antenna 3 and receives sensor data, the interrogator 1 transmits the “RFID tag 5 in the communication area” to the wireless tag 5 in the communication area. A "question command" is transmitted (T41). The wireless tag 5a and the wireless tag 5b that have received the “question command” from the interrogator 1 return the ID bits, respectively. In the case of the illustrated example, the wireless tag 5a returns “1” (T42), and the wireless tag 5b returns “0” (T43). At this time, the wireless tag 5d in the no-response state does not respond. The interrogator 1 receives “0” and “1” at the same time. When the interrogator 1 receives “0” and “1” at the same time, priority is given to “1” in this example. The interrogator 1 transmits a “1 confirmation command” to the wireless tag (T44). When the wireless tag receives a confirmation command having the same value as the ID returned by itself, the wireless tag returns the next ID bit. In the case of the illustrated example, the wireless tag 5a returns “0” (T45). The wireless tag 5b does not return a response to the interrogator 1 until the next “question command” is received.
[0059]
The interrogator 1 recognizes that the wireless tag 5 that has returned is only the wireless tag 5a, and transmits a “sensor request command” to the wireless tag (T46). The wireless tag 5a returns the sensor data stored after the address 01H in the EEPROM to the interrogator 1 (T47), and shifts to a no-response state (T49). During this time, the wireless tag 5d continues to store sensor data, and if the sensor data counter 90 exceeds the value of the no-response release value register 142, the no-response release signal 141 is generated in its own no-response release circuit 140 and no response is received. The state is released (T48).
[0060]
The interrogator 1 that has completed the data transfer with the wireless tag 5a transmits the “question command” again (T50). The wireless tag 5d and the wireless tag 5b that have received the “question command” from the interrogator 1 return an ID bit, respectively. In this case, the wireless tag 5d returns “1” (T51), and the wireless tag 5b returns “0” (T52). The interrogator 1 receives “0” and “1” at the same time. When the interrogator 1 receives “0” and “1” at the same time, it gives priority to “1”. The interrogator 1 transmits a “1 confirmation command” to the wireless tag (T53). When the wireless tag receives a confirmation command having the same value as the ID returned by itself, the wireless tag returns the next ID bit. In the case of the illustrated example, the wireless tag 5d returns “1” (T54). The wireless tag 5b does not return a response to the interrogator 1 until the next “question command” is received. The interrogator 1 recognizes that the wireless tag returned is only the wireless tag 5d, and transmits a “sensor request command” to the wireless tag 5d (T55). The wireless tag 5d returns the sensor data stored after the address 01H in the EEPROM to the interrogator 1 (T56).
[0061]
As described above, in the telemetry system using the wireless tag shown in FIGS. 22 and 23, the wireless tag 5 is provided with the no-response release value register 142 and the comparator 143 so that the wireless tag 5 is in the non-responsive state. When the sensor data is stored beyond the no-response release value register 142, the comparator 143 generates the no-response release signal 141 and shifts to the response state. If you use a wireless tag that can generate a no-response release signal in this way, the “initialization command” from the interrogator will not come, so the sensor data in the nonvolatile memory will be full, and the latest sensor The problem that data cannot be stored can be avoided. The application of this telemetry system is not limited to a medical telemetry system.
[0062]
Note that the priority bit setting circuit described with reference to FIGS. 16 to 21 and the no-response cancellation circuit described with reference to FIGS. A wireless tag with a priority bit setting circuit and a no-response canceling circuit is non-volatile when it is in a no-response state even if sensor data in the nonvolatile memory increases when it is in a question command waiting state in congestion control. It is possible to cope with an increase in sensor data in the memory.
[0063]
【The invention's effect】
According to the present invention, the sensor control circuit is provided in the wireless tag, the sensor data from the sensor connected to the wireless tag is stored in the wireless tag, and the stored sensor data is returned to the interrogator in response to a request from the interrogator. Since it did in this way, the signal of the sensor to which the wireless tag was connected can be monitored in real time. Further, if a priority bit setting circuit for generating a priority bit according to the usage rate of the sensor data storage area is provided in the wireless tag, a wireless tag having a high usage rate of the sensor data storage area can be preferentially processed. Furthermore, if the wireless tag is stored in a non-response state when the wireless tag is in a non-response state, the wireless tag has a function that can cancel the non-response state and shift to the response state. Since the “initialization command” does not come, the problem that the sensor data in the nonvolatile memory becomes full and the sensor data cannot be stored can be avoided.
[Brief description of the drawings]
FIG. 1 is an overall schematic diagram showing an example of a telemetry system according to the present invention.
FIG. 2 is a block diagram illustrating a configuration example of a wireless tag according to the present invention.
FIG. 3 is a block diagram illustrating a configuration example of an interrogator.
FIG. 4 is a diagram illustrating an example of a command.
FIG. 5 is a flowchart illustrating congestion control on the interrogator side.
FIG. 6 is a flowchart illustrating congestion control on the line tag side.
FIG. 7 is a state transition diagram of congestion control processing.
FIG. 8 is a state transition diagram of an ID / address designation read command.
FIG. 9 is a state transition diagram of an ID / address designation write command.
FIG. 10 is an explanatory diagram of a frame structure example of reply data.
FIG. 11 is a diagram for explaining an EEPROM memory map;
FIG. 12 is a diagram illustrating a configuration example of a sensor control circuit.
FIG. 13 is a diagram for explaining a procedure for storing sensor data.
FIG. 14 is a diagram for explaining an EEPROM access procedure;
FIG. 15 is a diagram showing a procedure for transferring sensor data from a selected wireless tag to an interrogator;
FIG. 16 is a diagram showing another configuration example of the wireless tag of the present invention.
FIG. 17 is a diagram showing a configuration example of a priority bit setting circuit.
FIG. 18 is an explanatory diagram of a priority bit setting table.
FIG. 19 is a diagram showing a structure example of a reply frame.
FIG. 20 is a diagram for explaining a priority bit writing procedure;
FIG. 21 is a diagram showing a procedure for transferring sensor data from a wireless tag to an interrogator.
FIG. 22 is a diagram showing another configuration example of the wireless tag of the present invention.
FIG. 23 is a diagram showing a configuration example of a no-response cancellation circuit.
FIG. 24 is a diagram for explaining an operation in which a no-response release signal is generated.
FIG. 25 is a diagram showing a procedure for transferring sensor data from a selected wireless tag to an interrogator.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 5 ... Wireless tag, 6 ... Sensor, 1 ... Interrogator, 21 ... Antenna, 23 ... Tag control circuit, 24 ... Sensor control circuit, 20 ... EEPROM, 22 ... Tag modulation / demodulation circuit, 3 ... Antenna, 33 ... CPU, 34 ... Memory 32... Transmission circuit 35. Reception circuit 31. Modulation / demodulation circuit 60. Priority bit setting circuit 91. Sensor data capacity register 93. Sensor data counter 92. Priority bit generation circuit 80. 140: No response cancel circuit 142: No response cancel value register 143: Comparator

Claims (5)

A wireless tag in a wireless tag system including a plurality of wireless tags that communicate with an interrogator,
An antenna,
A modulation / demodulation unit for performing modulation / demodulation processing for transmitting and receiving signals via the antenna;
A non-volatile memory having an identification area for storing an identification code and a data area for storing data;
A tag control unit that controls reading and writing of data to and from the nonvolatile memory;
A sensor control unit that converts an input signal from a connected external sensor into sensor data under the control of the tag control unit, and sends the sensor data to the tag control unit;
A priority bit representing a communication priority is generated based on the usage rate of the data area calculated from the capacity of the data area of the nonvolatile memory and the amount of sensor data stored in the data area, and the generated priority A communication priority setting unit that writes bits before the identification code of the identification region,
The tag control unit transmits the first bit of the priority bits when receiving a question command from an interrogator in a question command standby state, and then compares the priority bits received from a plurality of wireless tags as a response. Control is performed to receive a bit from an interrogator for determining a bit to be transmitted, transmit the next bit in the identification area if the received bit matches the transmission bit, and return to a query command waiting state if the bit does not match. A wireless tag characterized by being performed.   2. The wireless tag according to claim 1, wherein when the communication with the interrogator is completed, the sensor data stored in the data area of the nonvolatile memory is transferred to a no-response mode in which no reply is returned to the question command. A wireless tag comprising: a communication control initialization unit having a function of initializing a control state in a wireless tag and releasing a no-response mode when the amount of data exceeds a set value. In a telemetry system that includes an interrogator and a plurality of wireless tags connected to different sensors, respectively, and retrieves the data of each sensor individually through the interrogator,
The wireless tag includes a tag antenna, a modulation / demodulation unit that performs modulation / demodulation processing for transmitting and receiving signals via the tag antenna, an identification area for storing an identification code for identifying the wireless tag, and data for storing data A non-volatile memory having a region, a tag control unit that controls reading and writing of data to and from the non-volatile memory, and an input signal from a connected sensor is converted into sensor data under the control of the tag control unit. The communication priority is expressed based on the sensor control unit to be sent to the control unit, the capacity of the data region of the nonvolatile memory, and the usage rate of the data region calculated from the amount of sensor data stored in the data region. A communication priority setting unit that generates a priority bit and writes the generated priority bit before the identification code of the identification region,
The interrogator includes an antenna for communicating with a wireless tag, a modulation / demodulation unit for performing modulation / demodulation processing for transmitting / receiving a signal via the antenna, a memory for storing received data, and a command for the wireless tag. A transmission unit that transmits, a reception unit that analyzes a reception signal from the wireless tag, and a control unit that controls the operation of each unit;
Processing for transmitting a question command from the interrogator toward the plurality of wireless tags, processing for transmitting a first bit of each priority bit by a wireless tag that has received the question command, and sending the priority bits from the plurality of wireless tags The received interrogator determines the priority of each wireless tag based on the priority bit and transmits the received priority bit toward the high priority wireless tag, the received bit and the previously transmitted bit If the IDs match, the next bit of the identification area is transmitted, and if the IDs do not match, identification processing for identifying one wireless tag is performed by processing of the wireless tag to return to the question command waiting state.
A telemetry system, wherein the sensor data is read out from one identified wireless tag.   4. The telemetry system according to claim 3, wherein the interrogator transmits “1” to the plurality of wireless tags when receiving the bits “1” and “0” simultaneously in the identification process. Telemetry system.   4. The telemetry system according to claim 3, wherein when the communication with the interrogator is completed, the wireless tag shifts to a no-response mode in which no reply is returned to the question command, and is then stored in the data area of the nonvolatile memory. A telemetry system comprising: a communication control initialization unit having a function of initializing a control state in a wireless tag and releasing a no-response mode when the amount of sensor data exceeds a set value.

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