JP4618483B2 - Interrogator for RFID tag communication system and RFID tag communication system - Google Patents

Description

  The present invention relates to an interrogator of a wireless tag communication system that reads or writes information from and to a wireless tag capable of wireless communication of information with the outside, and a wireless tag communication system using the interrogator.

RFID ( Radio) that reads / writes information of a wireless tag by transmitting a query and receiving a response in a non-contact manner from a reader / writer as an interrogator with respect to a small wireless tag as a responder
There is known a Frequency Identification) system.

  For example, a wireless tag circuit element provided in a label-like wireless tag includes an IC circuit unit that stores predetermined wireless tag information and an antenna that is connected to the IC circuit unit and transmits and receives information. The IC circuit unit can be accessed (reading / writing information) from the reader / writer side even when the battery is dirty or in an invisible position, and can be used for product management, inspection processes, Practical use is expected in various fields such as search and detection of human movement.

  Conventionally, as a technique related to a human motion detection system using the wireless tag as described above, a warning area is divided into a number of warning spots, and a number of interrogators provided respectively corresponding to the number of warning spots. There is one that transmits a radio wave of a predetermined frequency from a (sensor) and tracks the movement trajectory of a person who has entered the area based on the reflected wave signal (see, for example, Patent Document 1).

  In this prior art, in order to identify whether the intruder in the area is an authorized person or an unauthorized person (= suspicious person), the authorized person is used as a responder for the authorized person. A hat equipped with a reflector that retransmits radio waves received from the sensor side as reflected waves and a RFID circuit element that modulates the received radio waves and transmits them as reflected waves are worn. Then, if the correct ID information is obtained by the reflected wave, the authorized person is identified. If the correct ID information is not obtained, the person is identified as the suspicious person. The movement of the authorized person or the suspicious person can be traced by tracing the reflected wave detected by each sensor in each warning spot in time series.

JP 2002-196073 A

  However, the above prior art is configured to arrange a plurality of sensors as interrogators, transmit radio waves in a fixed direction from each interrogator toward the spot of interest, and detect the reflected waves. For this reason, as the movement of the subject reaches a wider range, more interrogators are required to detect the movement, and a large number of reflected wave signals from each of the many interrogators are associated in time series. You must follow the trajectory. As a result, the detection operation control for a large number of interrogators and the calculation processing of a large number of detection signals have to be complicated, and it has been difficult to efficiently detect movement.

  An object of the present invention is to provide an interrogator for an RFID tag communication system capable of efficiently detecting movement with a small number of interrogators and an RFID tag communication system using the interrogator.

To achieve the above object, according to a first aspect of the present invention, there is provided an antenna comprising a plurality of antenna elements for performing non-contact information communication with an IC circuit portion of an RFID circuit element to be interrogated, and at least a carrier wave with the antenna. The information transmitting means for transmitting and accessing the RFID circuit element without contact via the contact, and the response signal returned from the IC circuit section according to the carrier wave transmitted by the information transmitting means via the antenna without contact The RFID circuit element is controlled in accordance with the result of communication with the IC circuit unit in at least two of the directivity directions. Direction detecting means for detecting the direction of movement of the antenna, wherein the direction detecting means is capable of switching the direction of directivity by the antenna. And a switching control means for controlling the direction switching means so that the direction changes sequentially while maintaining the directivity of the antenna to be strong in only one direction, and the switching control means includes: After the normal response signal is obtained by the information receiving means in one directivity direction of the antenna, when the magnitude of the received output of the response signal becomes less than a predetermined threshold, the RFID circuit The direction switching means is controlled so as to switch the antenna to another directivity direction following the moving direction of the element , and according to the directionality of the antenna to be switched by the direction switching means, Directivity control means for changing the directivity of the antenna is provided, and the directivity control means responds normally by the information reception means in a certain directivity direction with a wide width. If the magnitude of the received output of the response signal that can be received with the directivity is less than a predetermined threshold due to the movement of the RFID circuit element after the signal is obtained, the width direction of the antenna directivity It is characterized by reducing the range .
According to a second aspect of the present invention, in the first aspect, the switching control unit is configured to obtain a reception output of the response signal after the information reception unit has obtained a normal response signal in one directivity direction of the antenna. When the size is equal to or larger than the predetermined threshold value, the direction switching means is controlled to maintain the directivity direction of the antenna.
In order to achieve the above object, the third invention provides an antenna comprising a plurality of antenna elements for performing non-contact information communication with the IC circuit portion of the RFID tag circuit element to be queried, and at least a carrier wave with the antenna. The information transmitting means for transmitting and accessing the RFID circuit element without contact via the contact, and the response signal returned from the IC circuit section according to the carrier wave transmitted by the information transmitting means via the antenna without contact The RFID circuit element is controlled in accordance with the result of communication with the IC circuit unit in at least two of the directivity directions. Direction detecting means for detecting the direction of movement of the antenna, wherein the direction detecting means is capable of switching the direction of directivity by the antenna. And a switching control means for controlling the direction switching means so that the direction changes sequentially while maintaining the directivity of the antenna to be strong in only one direction, and the switching control means includes: The radio tag when the error rate when the response signal is demodulated becomes larger than a predetermined threshold after the normal response signal is obtained by the information receiving means in one directivity direction of the antenna. Controlling the direction switching means to switch the antenna to another directivity direction following the moving direction of the circuit element , and according to the directionality of the antenna to be switched by the direction switching means, Directivity control means for changing the directivity of the antenna is provided, and the directivity control means is normal by the information receiving means in a certain directivity direction with a wide width. After the response signal is obtained, if the error rate when the response signal that can be received with the directivity is demodulated by movement of the RFID circuit element is greater than a predetermined threshold, the antenna directivity The range in the width direction is made smaller .
In a fourth aspect based on the third aspect, the switching control means demodulates the response signal after the normal response signal is obtained by the information receiving means in one directivity direction of the antenna. When the error rate is less than or equal to the predetermined threshold value, the direction switching means is controlled to maintain the directivity direction of the antenna.

In the first to fourth inventions of the present application, when the RFID circuit element moves , the switching control unit of the moving direction detecting unit controls the direction switching unit based on the communication results with the IC circuit unit in a plurality of directivity directions. However, the directivity direction by the antenna composed of a plurality of antenna elements changes. Thus, changing the directivity direction of the antenna so as to track the movement direction of the RFID circuit element, the movement direction of the RFID circuit element as a result is detected. In this way, each interrogator tracks the movement of the RFID tag circuit element within a range in which the antenna directivity direction can be changed, so that the interrogators are simply arranged and moved without particularly changing the antenna directivity direction. Compared with the conventional structure for detecting the direction, it is possible to efficiently detect the movement of the RFID tag circuit element with a smaller number of interrogators.

  [0011]

  [0012]

  [0013]

Specifically, when the RFID circuit element moves, a response signal to the carrier wave from the information transmitting unit is received by the information receiving unit, and the magnitude of the received output of the received signal (or when the received signal is demodulated) The direction switching means is controlled based on the error rate) .

  [0015]

  [0016]

  [0017]

At this time, the directivity synthesized by the antenna in the direction switching means is changed so that the directivity is strengthened in only one direction, and the predetermined direction is changed according to the signal strength and phase difference of each antenna element in each direction. By performing (so-called phased array antenna control or beam forming control method), it is possible to easily estimate the existence direction and position of the RFID circuit element.

  [0019]

That is, after a response signal for the carrier wave from the information transmitting means is normally received by the information receiving means in one directivity direction and the RFID circuit element is captured , the response signal is received as the RFID circuit element moves. When the magnitude of the output is less than a predetermined threshold value (or when the error rate when the response signal is demodulated becomes larger than the predetermined threshold value), the RFID circuit element moves accordingly. The direction switching means switches the directionality direction of the antenna to another direction. While the magnitude of the reception output of the response signal is equal to or greater than a predetermined threshold (or while the error rate when demodulating the response signal is less than the predetermined threshold), the direction switching means is an antenna. It is sufficient to maintain the directivity of Thus, Ru can continue to track the wireless tag circuit element captured once to the moving direction.

  [0021]

  [0022]

In addition, when switching the directivity direction, it is a time when it is detected that the RFID circuit element is moving, and depending on the directivity direction, the direction of the directivity is switched to track the RFID circuit element that is moving. By doing so, it is possible to detect the movement optimally and reliably with few detection errors.

According to a fifth invention, in any one of the first to fourth inventions, the antenna includes a plurality of transmitting antenna elements, and the moving direction detecting means is a directivity by the plurality of transmitting antenna elements. It is characterized by controlling the direction.

  It is possible to detect the moving direction of the RFID tag circuit element by controlling the directivity direction of the transmitting antenna element used when transmitting from the interrogator to the RFID circuit element.

In a sixth aspect based on any one of the first to fifth aspects, the antenna includes a plurality of receiving antenna elements, and the moving direction detecting means is directed by the plurality of receiving antenna elements. It is characterized by controlling the direction.

  It is possible to detect the moving direction of the RFID tag circuit element by controlling the directivity direction of the receiving antenna element used at the time of reception by the interrogator from the RFID circuit element side.

In a seventh aspect based on any one of the first to sixth aspects, the antenna includes a plurality of transmitting / receiving antenna elements, and the moving direction detecting means transmits at least transmission by the plurality of transmitting / receiving antenna elements. It is characterized by controlling the direction of directivity at any one of time and reception.

  Controls the directivity direction at the time of transmission from the interrogator side to the RFID circuit element or reception at the interrogator from the RFID circuit element side in the antenna element for both transmission and reception, and detects the moving direction of the RFID circuit element be able to.

According to an eighth invention, in any one of the first to seventh inventions, the information transmitting unit and the information receiving unit perform information communication with the IC circuit units of the plurality of RFID tag circuit elements via an antenna. The moving direction detecting means detects the moving direction at predetermined time intervals for each of the plurality of RFID tag circuit elements.

  One movement direction detection means sequentially detects movement of a plurality of RFID tag circuit elements, and each of the RFID tag circuit elements detects movement at a predetermined time interval. It is possible to centrally manage movement.

A ninth invention is an interrogator provided in an RFID tag communication system having a plurality of interrogators according to the first or third invention, wherein the moving direction detecting means can detect the moving direction of the RFID circuit element. It is characterized by having a notification signal output means for outputting a notification signal to another interrogator adjacent on the moving direction side when it disappears.
By relaying to another interrogator when tracking becomes impossible with one interrogator, it is possible to efficiently detect movement with the smallest number of interrogators.
To achieve the above object, a tenth aspect of the present invention is an antenna comprising a plurality of antenna elements for performing information communication with the IC circuit part of the RFID circuit element of the question target and non-contact; the at least carrier said antenna An information transmitting means for transmitting and accessing the RFID circuit element in a non-contact manner via a contact; and a response signal returned from the IC circuit section in accordance with the carrier wave transmitted by the information transmitting means via the antenna in a non-contact manner. An information receiving means for receiving the radio tag circuit element according to a result of communication with the IC circuit unit in at least two of the directivity directions; and a moving direction detection means for detecting a moving direction of said moving direction detection means, switchable directional control the directivity by the antenna And a switching control means for controlling the direction switching means so as to sequentially change the direction while maintaining the directivity of the antenna to be strong in only one direction, the switching control means, After the normal response signal is obtained by the information receiving means in one directivity direction of the antenna, when the magnitude of the reception output of the response signal becomes less than a predetermined threshold, the wireless tag Controlling the direction switching means to switch the antenna to another directivity direction following the moving direction of the circuit element, and according to the directionality of the antenna to be switched by the direction switching means, The directivity control means for changing the width of the directivity by the antenna is provided, and the directivity control means is normal in the information receiving means in a certain directivity direction with a wide width. After the response signal is obtained, if the magnitude of the reception output of the response signal that can be received with the directivity is less than a predetermined threshold due to the movement of the RFID circuit element, the width of the antenna directivity A direction range is reduced; a plurality of interrogators are arranged along a predetermined or assumed movement path of the RFID tag circuit element.

In order to achieve the above object, an eleventh aspect of the present invention is an antenna comprising a plurality of antenna elements for non-contact information communication with an IC circuit portion of a RFID tag circuit element to be interrogated; An information transmitting means for transmitting and accessing the RFID circuit element in a non-contact manner via the antenna; and a response signal returned from the IC circuit section according to the carrier wave transmitted by the information transmitting means via the antenna. Information receiving means for receiving by contact; and controlling the direction of directivity by the antenna comprising the plurality of antenna elements, and depending on the result of communication with the IC circuit unit in the at least two directivity directions, the RFID circuit A moving direction detecting means for detecting a moving direction of the element, wherein the moving direction detecting means is capable of switching a direction of directivity by the antenna. Switching means, and switching control means for controlling the direction switching means so that the direction of the antenna changes sequentially while holding the antenna directivity strong in only one direction, the switching control means When an error rate when demodulating the response signal after the normal response signal is obtained by the information receiving means in one directivity direction of the antenna becomes greater than a predetermined threshold, The direction switching means is controlled so as to switch the antenna to another directivity direction following the moving direction of the RFID circuit element, and according to the directionality of the antenna to be switched by the direction switching means Directivity control means for changing the directionality of the antenna is provided, and the directivity control means is configured to receive the information receiver in a certain directivity direction with a wide width. If the error rate when the response signal that can be received with the directivity is demodulated by the movement of the RFID circuit element after the normal response signal is obtained at A plurality of interrogators are arranged along a predetermined or assumed movement path of the RFID tag circuit element.
In the tenth and eleventh inventions of the present application, when the RFID circuit element moves, each interrogator arranged along the movement path is based on the result of communication with the IC circuit unit in a plurality of directivity directions. The directionality direction of the antenna is changed by the moving direction detecting means. The switching control means changes the directivity direction of the antenna so as to track the moving direction of the RFID circuit element, and as a result, the moving direction of the RFID circuit element is detected. In this way, by tracking the movement of the RFID tag circuit element for each interrogator within a range in which the antenna directivity direction can be changed, the interrogators are simply arranged without particularly changing the antenna directivity direction. Compared to the conventional structure for detecting the moving direction, it is possible to efficiently detect the movement of the RFID circuit element with a smaller number of interrogators. Further, in each interrogator, by switching the directivity width according to the directivity direction and tracking the RFID circuit element that is moving, it is possible to perform an optimal and reliable movement detection with few detection errors.

In a twelfth aspect based on the tenth or eleventh aspect , each of the plurality of interrogators moves at a predetermined timing when the moving direction detecting means detects the moving direction of the RFID circuit element. It has a notification signal output means for outputting a notification signal to another interrogator located on the direction side.

  Since there is a limit in the tracking range of one interrogator, it moves by outputting a notification signal to another interrogator on the traveling direction side by a notification signal output means at a predetermined timing during the tracking. The interrogator can be relayed and tracked sequentially without losing sight of the RFID tag circuit elements.

In a thirteenth aspect based on the twelfth aspect , the notification signal output means, when the movement direction detection means cannot detect the movement direction of the RFID circuit element, is adjacent to the movement direction side. A notification signal is output to the interrogator.

  By relaying to an adjacent interrogator when it becomes impossible to track with one interrogator, it is possible to efficiently detect movement with the smallest number of interrogators.

A fourteenth invention is characterized in that, in any one of the tenth to thirteenth inventions, the plurality of interrogators are alternately arranged in a substantially staggered pattern along the movement path on both sides of the movement path. And

  By adopting a substantially staggered arrangement, the base points of antenna directivity are alternately reversed between the interrogator on one side and the interrogator on the other side of the movement path, and the overlap between the trackable ranges in adjacent interrogators is reduced. In addition, since the number of interrogators required is further reduced, it is possible to efficiently detect movement without waste.

  According to the present invention, each interrogator tracks the movement of the RFID circuit element within a range in which the directionality of the antenna can be changed. Therefore, the movement can be detected efficiently with a small number of interrogators.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a system configuration diagram showing an overall outline of an RFID tag communication system to which this embodiment is applied.

  In FIG. 1, the RFID tag communication system S includes a plurality of (but only one of) interrogators 100 according to the present embodiment and a RFID tag T as a responder corresponding thereto.

  The wireless tag T includes a wireless tag circuit element To including an antenna 151 and an IC circuit unit 150.

  A plurality of interrogators 100 are arranged along the movement path of the wireless tag T (see also FIG. 5 described later). Each interrogator 100 exchanges signals with the antenna 151 of the RFID circuit element To by wireless communication. In this example, the interrogator 100 includes three antenna elements (hereinafter the same) 1A, 1B, 1C array antenna 1 ( The same applies to the following), the high-frequency circuit 2 for accessing (reading or writing) the IC circuit unit 150 of the RFID circuit element To via the antennas 1A to 1C, and the RFID circuit element To A signal processing circuit 3 for processing signals and a control circuit 4 are provided.

  The antennas 1A, 1B, and 1C have directivity in the moving path plane of the wireless tag T, and are configured so that the direction in which transmission or reception can be performed with the maximum power is variable.

  The control circuit 4 is a so-called microcomputer, and although not shown in detail, it is composed of a central processing unit such as a CPU, a ROM, and a RAM, and is stored in advance in the ROM while using a temporary storage function of the RAM. Signal processing is performed according to the program.

  FIG. 2 is a block diagram showing an example of a functional configuration of the RFID circuit element To provided in the RFID tag T.

  In FIG. 2, the RFID circuit element To is the antenna 151 (tag-side antenna; antenna element) that performs non-contact signal transmission / reception with the antennas 1A to 1C on the interrogator 100 side using a high frequency such as UHF band. And the IC circuit unit 150 connected to the antenna 151.

  The IC circuit unit 150 includes a rectifying unit 152 that rectifies the carrier wave received by the antenna 151, a power source unit 153 that accumulates energy of the carrier wave rectified by the rectifying unit 152 and serves as a driving power source, and the antenna 151. A clock extraction unit 154 that extracts a clock signal from the received carrier wave and supplies the clock signal to the control unit 157; a memory unit 155 that functions as an information storage unit that can store a predetermined information signal; and a modem that is connected to the antenna 151 And a controller 157 for controlling the operation of the RFID circuit element To via the rectifier 152, the clock extractor 154, the modem 156, and the like.

  The modem unit 156 demodulates the communication signal received from the antenna 151 from the transmission antenna 10 of the RFID tag reader 1 and received from the antennas 1A to 1C based on the return signal from the control unit 157. Reflectively modulate the carrier wave.

  The control unit 157 interprets the received signal demodulated by the modulation / demodulation unit 156, generates a return signal based on the information signal stored in the memory unit 155, and performs basic control such as returning by the modulation / demodulation unit 156. Execute proper control.

  FIG. 3 is a functional block diagram showing a functional configuration of the high-frequency circuit 2 provided in the interrogator 100.

  In FIG. 3, the high-frequency circuit 2 includes a directivity control unit (phased array control unit or beamforming control unit) 211 connected to the antennas 1 </ b> A to 1 </ b> C having both transmission and reception functions, and an antenna via the directivity control unit 211. 1A to C includes a transmission unit 212 that transmits a signal to the RFID circuit element To and a reception unit 213 that receives a reflected wave from the RFID circuit element To that is received by the antennas 1A to C.

  The directivity control unit 211 includes transmission phase control units 201A, 201B, and 201C related to the antennas 1A, 1B, and 1C, reception phase control units 202A, 202B, and 202C related to the antennas 1A, 1B, and 1C, and a reception phase control unit 202A. , 202B, 202C, the adder 203 for adding the outputs, the transmission phase control unit 201A or the reception phase control unit 202A and the antenna 1A are connected in one direction, that is, the signal from the transmission phase shift control unit 201 is connected to the antenna. At the same time as transmitting to the element 1A, a signal received by the antenna element 1A is transmitted to the reception phase control unit 202A (for example, comprising a circular radar, etc.) and a transmission / reception separator 204A and a transmission phase control unit 201B or reception phase control unit 202B and antenna 1B It has a transmit-receive splitter 204B to unidirectionally connected, and a transmit-receive splitter 204C to a transmission phase control unit 201C or reception phase control unit 202C and the antenna 1C unidirectionally connected.

  The transmission phase control units 201A, 201B, and 201C receive the transmission phase control signal from the control circuit 4, and phase shifters 205A and 205B that variably set the phase of the transmission radio signal in the antennas 1A, 1B, and 1C according to the transmission phase control signal. , 205C and the amplitude control signal included in the transmission phase shift control signal from the control circuit 4 are input, and the signals input from the phase shifters 205A, 205B, 205C are amplified in response to this, and the transmission / reception separators 204A, 204B, Transmitter-side variable gain amplifiers 206A, 206B, and 206C that output to 204C, respectively.

  The reception phase control units 202A, 202B, 202C receive the reception phase control signal from the control circuit 4, and in accordance with this, phase shifters 207A, 207B that variably set the phase of the reception radio signal at the antennas 1A, 1B, 1C. , 207C and the amplitude control signal included in the received phase control signal from the control circuit 4, the signals input from the phase shifters 207A, 207B, 207C are amplified in accordance with this, and output to the adder 203 Variable gain amplifiers 208A, 208B, and 208C are provided. A variable attenuator may be used instead of the transmission side variable gain amplifiers 206A, 206B, 206C and the reception side variable gain amplifiers 208A, 208B, 208C.

  The transmission unit 212 includes a crystal oscillation circuit or a PLL-controlled oscillation circuit 215 that generates a carrier wave for accessing (reading / writing) the RFID tag information of the IC circuit unit 150 of the RFID circuit element To, and the control described above. A transmission side multiplication circuit 216 that modulates the generated carrier wave based on the signal supplied from the circuit 4 (in this example, amplitude modulation based on the “TX_ASK” signal from the control circuit 4). A variable rate amplifier or the like may be used). This carrier wave is desirably set to a vicinity of 900 MHz or 2.45 GHz, and the modulated wave modulated by the transmission side multiplication circuit 216 is supplied to the transmission phase control units 201A, 201B, and 201C, and the transmission / reception separators 204A and 204B. , 204C and the antennas 1A, 1B, 1C are supplied to the IC circuit unit 150 of the RFID circuit element To.

  The receiving unit 213 generates a reflected wave from the RFID circuit element To received by the antennas 1A, 1B, and 1C and summed by the adder 203 through the reception phase control units 202A, 202B, and 202C and generated by the transmitting unit 212. A reception side first multiplication circuit 218 for multiplying the received carrier wave, a first band pass filter 219 for extracting only a signal of a necessary band from the output of the reception side multiplication circuit 218, and the first band pass filter 219. The reception side first amplifier 221 that amplifies the output of the signal and supplies it to the first limiter 220, and is received by the reception antennas 1A, 1B, and 1C, and summed by the adder 203 via the reception phase control units 202A, 202B, and 202C. The reflected wave from the RFID tag circuit element To and the carrier wave generated by the transmitter 212 and delayed in phase by 90 ° A reception-side second multiplication circuit 222 for multiplying the wave, a second band-pass filter 223 for extracting only a signal of a necessary band from the output of the reception-side second multiplication circuit 222, and the second band-pass filter 223. And a receiving-side second amplifier 225 for amplifying and supplying the output to the second limiter 224. The signal “RXS-I” output from the first limiter 220 and the signal “RXS-Q” output from the second limiter 224 are input to the signal processing circuit 3 and processed.

  The outputs of the reception-side first amplifier 221 and the reception-side second amplifier 225 are also input to an RSSI (Received Signal Strength Indicator) circuit 226, and a signal “RSSI” indicating the strength of those signals is input to the signal processing circuit 3. It is designed to be entered. Thus, in the RFID tag reading device 1 of the present embodiment, the reflected wave from the RFID tag circuit element To is demodulated by IQ orthogonal demodulation.

  The signal processing circuit 3 inputs a received signal from the above-described high-frequency circuit receiving unit 213, performs predetermined arithmetic processing, and outputs a modulation control signal to the transmission-side multiplication circuit 216 of the transmitting unit 212 in response thereto. . The control circuit 4 outputs a phase control signal or the like to the transmission phase control units 201A, 201B, 201C and the reception phase control units 202A, 202B, 202C according to the calculation processing result of the signal processing circuit 3. The control circuit 4 is connected to, for example, a communication line via, for example, an input / output interface (not shown), a route server (not shown) connected to the communication line, another terminal, a general-purpose computer, an information server, and the like Information may be exchanged between the two.

  In the present embodiment, directivity control by so-called phased array control or beam forming control is performed in which the directivity by a plurality of antennas 1A, 1B, and 1C is maintained so that only one direction is strengthened and the direction is sequentially changed. When a signal is received, if one signal propagates from an angle with respect to the antennas 1A, 1B, and 1C, a difference in the phase of the received radio wave is caused by the difference in the path length of the antennas 1A, 1B, and 1C. And the phase shifter is controlled by the received phase control signal so as to eliminate this phase difference, so that the directivity direction can be directed to the direction of the wireless tag T (and also when the signal is transmitted) Signal transmission is performed with the directivity according to the position where the wireless tag T exists on the same principle). In particular, in the interrogator 100 of the present embodiment, the control circuit 4 changes the directivity of the array antenna including the antenna elements 1A to 1C on the premise that the RFID tag T moves, so that The biggest feature is to detect the moving direction.

  FIG. 4 is an explanatory diagram conceptually showing the detection behavior of the moving direction of the wireless tag T by the interrogator 100.

  In FIG. 4, the directivity control unit 211 of the high frequency circuit 2 can switch the directivity directions (both transmission and reception) by the antennas 1A, 1B, and 1C to a plurality of directions by the control signal of the control circuit 4 of the interrogator 100. After the radio tag T is captured in a certain directivity direction (FIG. 4 (a)), when the reception intensity that can be received in the directivity direction decreases due to the movement of the radio tag T (FIG. 4 (b)), the beam The directivity direction is swung from the previous direction to the left and right sides, and the directivity direction in which the reception intensity increases again is searched (FIG. 4C). In this way, it is possible to detect in which direction the RFID tag T is moving (= tracking).

  Further, in the present embodiment, a plurality of interrogators 100 that perform the detection behavior as described above are arranged along the movement path direction (preset or assumed) of the wireless tag T to move the wireless tag T. Accordingly, the interrogator 100 that performs detection among the plurality of interrogators 100 is sequentially switched along the moving direction (= coordinate tracking by the plurality of interrogators 100).

  FIG. 5 is an explanatory diagram conceptually showing the movement tracking behavior of the wireless tag T by the plurality of interrogators 100.

  In FIG. 5, each interrogator 100 follows the movement of the wireless tag T after capturing the wireless tag T with a certain directivity by the directivity switching control of the high-frequency circuit 2 as described above (FIG. 5A). In this way, the directivity is changed (FIG. 5B), and when the change in directivity reaches the limit (FIG. 5C), the direction of movement of the wireless tag T (in this example, the right side in the figure) A predetermined notification (= notification of requesting succession of tracking) is made to the next adjacent interrogator 100. This notification may be performed by a known appropriate method, or may be performed by wireless communication using the antennas 1A, 1B, and 1C. In response to this, the next interrogator 100 captures the RFID tag T in a certain directivity as described above (FIG. 5 (d)), changes the directivity in the same manner, and the change in directivity reaches the limit. (FIG. 5 (e)) Further, a predetermined notification is sent to the next adjacent interrogator 100, and the adjacent next interrogator 100 captures the wireless tag T (FIG. 5 (f)). The same acquisition / tracking procedure is repeated while notifying the interrogator 100. In this way, the interrogator 100 can be sequentially relayed and tracked without losing sight of the moving RFID tag T.

  6 and 7 are flowcharts showing a control procedure performed by the control circuit 4 of one interrogator 100 in order to execute the directivity switching control in the antennas 1A, 1B, and 1C of the interrogator 100 described above.

  First, in FIG. 6, tag search (tracking) start is started after information related to a search target (for example, identification number of the RFID circuit element To, ID number, etc.) is input from an operation unit (not shown), for example. This flow is started when there is an appropriate instruction to that effect.

  First, in step S10, at the time of searching, a certain reference position (for example, a question) when changing the direction while holding the directivity (both transmission and reception in this example) of the array antenna 1 strong in only one direction. Directivity angle (hereinafter referred to as a directivity angle) θ from the origin 100 side of the moving path of the RFID tag T as viewed from the device 100 is 0 °, and the angle increases in the direction toward the end point (the same applies hereinafter) θ. Is set to θ = θs. The value of θs may be stored in advance in the RAM of the control circuit 4 in a fixed manner, may be stored in a rewritable manner, or may be input every time a search is performed.

  Next, the process proceeds to step S20, and it is determined whether or not the interrogator 100 has received a notification corresponding to the tag moving direction from another interrogator 100 as described above.

(1) When there is no notification In other words, for example, when the wireless tag T can be detected by another interrogator, the notification is not notified, so the determination at Step S20 is not satisfied, and the routine goes to Step S100A.

  In step S100A, tag detection processing is performed, a call signal is transmitted to the RFID tag T to be detected by the antenna 1 whose phase is controlled according to the value of the directivity angle θ, and if there is a response signal, it is captured and further received. The signal strength signal is stored (refer to FIG. 8 described later for details). After step S100A is completed, the process proceeds to step S30.

  In step S30, it is determined whether or not the wireless tag T has been detected (captured) by the tag detection process. If it is captured (when a valid response signal for the call is received), the determination is satisfied, and the routine goes to Step S130 shown in FIG. If not captured, the determination is not satisfied, and in step S40, a predetermined Δθ is added to the directivity angle θ. As a result, the next search is performed in the directivity direction shifted in the direction of increasing the angle by Δθ.

  Thereafter, the process proceeds to step S50, and it is determined whether or not θ is larger than θe (for example, the end point of the directivity angle θ change range) set as a final value when the directivity angle θ is sequentially changed. If the tag search is just started, θ is smaller than θe, so this determination is not satisfied and the routine returns to step S20, and the same search is repeated in the directivity direction in which the directivity angle θ is increased by Δθ. If the tag search is performed several times, but the RFID tag T is not found and θ is greater than θe, the above determination is satisfied, the process proceeds to step S60, and θ = θs is reset to search again from the beginning. Then, returning to step S20, the same search is repeated.

  As described above, while the search is repeated as step S20 → step S100A → step S30 → step S40 → step S50 → (step S60) → step S20 →, the determination of step S30 is satisfied when the wireless tag T is detected. The process moves to step S130.

(2) When there is a notification In other words, in the interrogator 100 arranged on the moving path of the wireless tag T, the tracking succession request notification is input as described above from the interrogator 100 adjacent to the moving direction starting point side, for example. If it does, the determination of the said step S20 will be satisfy | filled and it will move to step S70.

  In step S70, the notification is from the interrogator 100 adjacent to the starting point side (direction s) (= the wireless tag T is moving in the forward direction as originally assumed) or to the ending point side (direction e). It is determined from the adjacent interrogator 100 (= the wireless tag T is moving in the opposite direction opposite to the original assumption). If it is the forward direction, the determination is satisfied and the directivity angle θ = θs is set in step S80A, and if it is the reverse direction, the determination is not satisfied and the directivity angle θ is set to the aforementioned θe in step S80B.

  When step S80A or step S80B is completed, the process proceeds to step S100B, the tag detection process is performed in the same manner as step S100A, and the process proceeds to step S90.

  In step S90, it is determined whether or not the wireless tag T has been detected (captured) by the tag detection process. If it is captured (when a valid response signal for the call is received), the determination is satisfied, and the routine goes to Step S130 shown in FIG.

  If it is not captured, the determination is not satisfied, and whether or not a predetermined time has passed in a step S110 while the tag is not captured by a timer (not shown) in the control circuit 4 (= predetermined time after first moving to step S110) Whether or not the time has passed is determined. Until the time elapses, the determination is not satisfied, and the process returns to step S100 and the same procedure is repeated (retry for tag capture). If the wireless tag T is not captured even after the predetermined time elapses, the determination in step S110 is satisfied, and the process proceeds to step S120 to perform a predetermined error notification. This error notification may be made to output a display signal for displaying the notification to that effect on the display means provided in the interrogator 100, or to notify other interrogators 100 to that effect. It may be. Or you may make it display on the computer terminal, server, etc. which were provided separately from the control circuit 4 via the above-mentioned network. When step S120 ends, the process returns to step S20 and the same procedure is repeated.

  FIG. 7 is a flowchart showing a subsequent control procedure when the target wireless tag T can be captured (detected) in the flow shown in FIG.

  In FIG. 7, as described above, when the wireless tag T of FIG. 6 is captured and the determination in step S30 or step S90 is satisfied, the process proceeds to step S130. In step S130, it is determined whether or not the received signal strength stored in step S100A (or step S100B) described above at the time of acquisition is a predetermined value. If it is equal to or greater than the predetermined value, the determination is satisfied, and it is considered that there is no need to change the directivity direction of the current antennas 1A, 1B, and 1C, and the same procedure is repeated by returning to S100B of FIG.

  In this way, if the received signal strength becomes less than a predetermined value due to the movement of the wireless tag T while repeating Step S100B → Step S90 → Step S130 → Step S100B..., The determination in Step S130 is not satisfied and the wireless It is considered that the directivity directions of the antennas 1A, 1B, and 1C need to be changed according to the movement of the tag T, and the process proceeds to step S140.

  In step S140, the directivity angle θ is set to the current directivity direction θx.

  Next, in step S150, a predetermined Δθ (may be the same value as step S40 described above or a different value) is added to the current directivity angle θx. As a result, the next search is performed in the directivity direction θ shifted by Δθ in the direction of increasing angle.

  Thereafter, the process proceeds to step S160, and it is determined whether or not θ is larger than the above θe. In this example that moves after step S140, since θ is smaller than θe, this determination is not satisfied, and the routine goes to step S100C.

  In step S100C, the tag detection process exactly the same as in steps S100A and S100B described above is performed in the directivity direction in which the directivity angle θ is increased by Δθ, and the process proceeds to step S170.

  In step S170, it is determined whether or not the received signal strength obtained by the tag detection process in step S100C is a predetermined value. If it is equal to or greater than the predetermined value, the determination is satisfied, the movement direction of the RFID tag T is detected, and the directivity directions of the antennas 1A, 1B, and 1C are completed following the movement (= the directivity becomes the current position of the RFID tag T). 6), the process returns to step S90 in FIG. 6 and the same procedure is repeated.

  If the received signal strength is less than the predetermined value, the determination is not satisfied, and tracking by changing the directivity direction of the antennas 1A, 1B, and 1C is inappropriate compared to the moving direction of the wireless tag T (= directivity change). The direction was opposite to the direction of movement of the RFID tag T, or the change direction was correct but the movement speed of the RFID tag T was exceeded and the directivity was switched to the front side thereof, or the movement of the RFID tag T The direction has been changed), and the process moves to step S180.

  In step S180, Δθ (which may be the same value as described above or may be a different value) is subtracted from the directivity angle θ. As a result, the next search is performed in the directivity direction shifted in the angle decreasing direction by Δθ (that is, the directivity direction is changed to the opposite side to the angle increasing direction so far).

  Thereafter, the process proceeds to step S190, and it is determined whether or not θ is smaller than θs. If the above step S180 is repeated many times and θs does not become considerably small, θ is equal to or greater than θs. Therefore, in the present embodiment, this determination is not satisfied and the process proceeds to step S100D.

  In step S100D, the tag detection processing exactly the same as that in steps S100A to C described above is performed in the directivity direction in which the directivity angle θ is decreased by Δθ, and the process proceeds to step S200.

  In step S200, it is determined whether or not the received signal strength obtained by the tag detection process in step S100D is a predetermined value. If it is equal to or greater than the predetermined value, the determination is satisfied, and the same procedure is repeated by returning to step S90 shown in FIG.

  As described above, step S100B → step S90 → step S130 is repeated while the received signal strength by the tag detection process is equal to or greater than a predetermined value. If the received signal strength becomes smaller than a predetermined value due to the movement of the wireless tag T during this repetition, the directivity angle θ of the antennas 1A, 1B, 1C is increased by step S140 → step S150 → step S160 → step S100C → step S170. Or by changing the directivity angle θ of the antennas 1A, 1B, and 1C in the direction of decreasing angle in step S180 → step S190 → step S100D → step S200 so that the received signal strength becomes a predetermined value or more. The movement of the RFID tag T is tracked while changing the directivity of the antennas 1A, 1B, and 1C.

  If the directivity angle θ of the antennas 1A, 1B, and 1C increases during the tracking repetitive procedure and exceeds the above θe, the determination in step S160 is satisfied, and the process proceeds to step S220. After step S220, it is considered that the limit of tracking in the increasing direction of the directivity angle θ by the interrogator 100 has been reached, and the tracking succession to the interrogator 100 adjacent in the increasing direction is started. In step S220, as preparation, first, Δθ is subtracted from θ (= in other words, Δθ added in the immediately preceding step S150 is restored), and then in step S100E again, the above steps S100A to The same tag detection processing as that for D is performed, and the received signal strength is determined again in step S230. If the received signal strength is restored to a predetermined value or more by this operation, the determination is satisfied, and the process returns to step S90 and the same procedure is repeated. However, if the received signal strength is less than the predetermined value, the interrogator 100 increases in the θ direction. In step S240, the tracking succession request notification described above is output to another interrogator 100 adjacent to the movement path end point side of the RFID tag T in step S240. After step S240 ends, the process returns to step S20 (capture standby state).

  If the directivity angle θ of the antennas 1A, 1B, and 1C decreases and becomes smaller than θs during the tracking repetitive procedure as described above, the determination in step S190 is satisfied, and the process proceeds to step S250. In step S250, the RFID tag T moves in the opposite direction, contrary to the above, and it is considered that the tracking limit in the θ decreasing direction by the interrogator 100 has been reached. The above-mentioned tracking succession request notification is output to the interrogator 100. After step S250 is completed, θ is returned to the aforementioned θs in step S260, and then the process returns to step S20 (capture standby state).

  If the received signal strength is less than the predetermined value in step S200 described above during the tracking repetitive procedure, the determination in step S200 is not satisfied. In this case, even if the wireless tag T is captured in step S30 or step S90, the reception strength does not increase even if the directivity is changed in either the angle increasing direction or the decreasing direction in step S150 or step S180. It is considered that the tag T has been lost, and the process proceeds to step S210, where a predetermined error notification is performed. This error notification may be made to output a display signal for displaying the notification to that effect on the display means provided in the interrogator 100, or to notify other interrogators 100 to that effect. It may be. Or you may make it display on the computer terminal, server, etc. which were provided separately from the control circuit 4 via the above-mentioned network. When step S210 is completed, the process returns to step S20 and the same procedure is repeated.

  FIG. 8 is a flowchart showing the detailed procedure of step S100.

  In FIG. 8, first, in step S102, the phases related to the antennas 1A, 1B, 1C are determined according to the value of the directivity angle θ, and the phase control signals corresponding thereto are transmitted to the transmission phase control units 201A, 201B, 201C ( Alternatively, the data is output to the reception phase control units 202A, 202B, 202C).

  Thereafter, the process proceeds to step S104, and the array antenna 1 applies the target RFID tag T to the target RFID tag T under the condition that the phases of the antenna elements 1A, 1B, and 1C are set (in other words, the directivity angle θ is set) as described above. A ScrollID signal that is a call signal is output. More specifically, the control circuit 4 outputs a control signal to the signal processing circuit 3, generates a “TX_ASK” signal, outputs the signal to the transmission side multiplication circuit 216, and the transmission side multiplication circuit 216 performs the above-described amplitude modulation and performs access. It becomes a “Scroll ID” signal as information. On the other hand, the control circuit 4 generates a “TX_PWR” signal and outputs it to the transmission phase control units 201A, 201B, and 201C. The transmission side amplifiers 206A, 206B, and 206C perform signal amplification at an amplification factor based on the “TX_PWR” signal. Finally, it is transmitted via the antennas 1A, 1B, and 1C, and prompts a reply from the RFID tag circuit element To of the RFID tag T to be detected.

  Thereafter, in step S106, a response signal (= reply signal; RFID tag information including at least identification information) transmitted from the RFID tag circuit element To of the RFID tag T to be detected in response to the “Scroll ID” signal is sent to the antenna. The signals are received from 1A, 1B, and 1C, phase-controlled by the reception phase control units 202A, 202B, and 202C, and then captured by the signal processing circuit 3 via the adder 203 and the high-frequency circuit receiving unit 213. At this time, the received signal strength signal “RSSI” from the RSSI circuit 226 is input to the control circuit 4 via the signal processing circuit 3, and the value is stored in an appropriate storage means such as a RAM in the control circuit 4 (or the control circuit). 4 may be stored in an external storage means other than 4 or may be non-volatile. If no reply signal is received, it is determined that the wireless tag T cannot be detected.

  When step S106 ends in this way, this routine ends.

  In the above description, the antennas 1A, 1B, and 1C constitute a transmitting antenna element and a receiving antenna element as described in each claim, and further constitute a transmitting / receiving antenna element.

  Further, the directivity control unit 211 of the high-frequency circuit 2 and the entire procedure of the flow of FIG. 6 performed by the control circuit 4 and steps S130 to S200 (including steps S100C and S100D) of the flow of FIG. The direction of directivity by the antenna element is controlled, and a moving direction detecting means for detecting the moving direction of the RFID circuit element according to the communication result with the IC circuit unit in the at least two directivity directions is configured. . Among them, the directivity control unit 211 constitutes a direction switching unit capable of switching the direction of directivity by a plurality of antenna elements, and the entire procedure of the flow of FIG. 6 performed by the control circuit 4 and steps S130 to S130 of the flow of FIG. The procedure of step S200 (including step S100C and step S100D) follows a moving direction of the RFID circuit element according to the result of communication with the IC circuit unit in at least two directivity directions of the plurality of antenna elements. A switching control means for controlling the direction switching means is configured so that the direction of directivity by the antenna element can be switched.

  Further, when the procedure of steps S220 to S240 (including step S100E) and step S250 of the flow of FIG. 7 performed by the control circuit 4 detects the moving direction of the RFID circuit element by the moving direction detecting means, a predetermined value is set. The notification signal output means for outputting a notification signal to another interrogator located on the moving direction side at the timing is configured.

  Further, the transmission unit 212 of the high-frequency circuit 2 constitutes an information transmission unit that transmits at least a carrier wave to the RFID tag circuit element in a non-contact manner via a plurality of antenna elements, and the reception unit 213 is configured by the information transmission unit. During transmission of a carrier wave, an information receiving means is configured to receive a response signal returned from the IC circuit unit in response to the transmitted carrier wave in a non-contact manner via a plurality of antenna elements.

  In the RFID tag communication system S using the interrogator 100 of the present embodiment configured as described above, the interrogator 100 normally receives a response signal to the carrier wave from the transmission unit 212 at a certain directivity angle θ by the reception unit 213. When the response signal changes as the wireless tag T moves after the wireless tag T is captured, the antenna is adapted to track in the moving direction of the wireless tag T according to the magnitude of the received intensity of the response signal at that time. The directivity angle θ of 1A to C is increased, decreased, or changed, and the wireless tag T once captured is tracked in the moving direction. In this way, by tracking the movement of the wireless tag T within a range in which the directivity angle θ of the antennas 1A to 1C can be changed by each of the plurality of interrogators 100 arranged along the movement path, the directivity of the antenna is obtained. Compared with the conventional structure in which the interrogators are simply arranged and the moving direction is detected without changing the direction in particular, the movement of the RFID tag circuit element can be efficiently detected with a smaller number of interrogators. Further, even within the detection range of each interrogator 100, tracking is performed by changing the directivity direction following the movement of the wireless tag T, so that long-time communication and a large amount of data can be exchanged. Furthermore, as described above, since the RFID tag T is always stationary, moving, or moving, it is always possible to know which direction it is, so it is effective for taking out goods and managing security for outpatients. It is.

  In particular, since there is a limit in the trackable range of one interrogator 100, a notification signal is output to another interrogator 100 in the traveling direction when the tracking limit is reached (Step S240 in FIG. 7). By performing step S260), it is possible to reliably perform tracking with the minimum number of interrogators while sequentially relaying the interrogators 100 without losing sight of the moving radio tag T.

  The present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit and technical idea of the present invention. Hereinafter, such modifications will be described in order.

(1) Other aspects in directivity control In the above embodiment, the antennas 1A to 1A in each direction are sequentially changed while keeping the directivity synthesized by the antennas 1A to 1C to be strong in only one direction. The so-called phased array antenna control or beam forming control for specifying the position of the RFID tag T by performing a predetermined calculation process according to the signal strength and the phase difference of C is performed. However, the present invention is not limited to this. An aspect may be sufficient. That is, as long as the moving direction of the wireless tag T is detected, a response signal from the wireless tag T is received in a predetermined angular direction (at least two) fixed in advance, and the larger received signal is The control may be such that the directivity is switched. In short, it is sufficient to detect the moving direction of the wireless tag T according to the communication result with the IC circuit unit 150 in at least two directivity directions of the antennas 1A to 1C.

  Further, in the above, when the signal strength of the response signal from the wireless tag T becomes less than a predetermined threshold value in step S130 or step S170 in FIG. 7, the directivity directions of the antennas 1A to 1C are changed to other directions. Although it changed by changing, it is not restricted to this. That is, instead of the magnitude of the signal intensity, the error rate when the response signal is demodulated is used, and when this error rate exceeds a predetermined threshold, the directivity directions of the antennas 1A to 1C are changed to other directions. You may make it change by switching to. In this case, the same effect is obtained.

(2) Wide and narrow change of directivity itself In the above embodiment, when the directivity control unit 211 controls the directivity direction of the antennas 1A, 1B, 1C, the directivity width (range) itself is not changed. However, the width is not limited to this, and the width may be changed according to the direction of directivity.

  9 (a), 9 (b), and 9 (c) are diagrams showing an example of directivity control in such a modification, and FIG. 4 (a) and FIG. 4 (b) respectively. FIG. 5 is a diagram corresponding to FIG. In this example, based on the control signal from the control circuit 4, the directivity control unit 211 captures the wireless tag T in a certain directivity direction with a larger width (FIG. 9A), and then moves the wireless tag T. When the reception strength that can be received with the directivity decreases (FIG. 9B), the beam directivity direction is shifted from the previous direction to the left and right sides, and the directivity direction in which the reception strength increases again is searched ( FIG. 9 (c)). At this time, when the directivity direction is swung to both sides as shown in FIG. 9C, the range of the directivity width direction of the antennas 1A to 1C is reduced.

  In the above description, the control circuit 4 also constitutes directivity control means for changing the directivity of the plurality of antenna elements in accordance with the directionality of the plurality of antenna elements switched by the direction switching means.

  As described above, in this modification, once the wireless tag T is captured, the directivity is widened only for detecting the position of the wireless tag T, and the wireless tag T moves within the range. Can always grasp the location. When the wireless tag T moves out of the directivity range, the direction of the wireless tag T is searched by switching to a narrower directivity and swinging the directivity direction to both sides. In this way, by tracking the RFID circuit elements that are moving while switching the directivity size (wide or narrow) during tracking, it is possible to perform optimal and reliable movement detection with few detection errors.

(3) Antenna In the above embodiment, directivity control by phased array control or beamforming control is performed for both transmission and reception. However, the present invention is not limited to this, and directivity control is performed only for transmission or reception. May be. As an example of directivity control for reception only, at the time of transmission, the gains of the variable gain amplifiers 206B and 206C of the transmission phase control units 201B and 201C are set to 0 so that the antennas 1B and 1C are not involved in transmission. It is sufficient to perform transmission only with this. At this time, it is more preferable to widen the directivity range of the antenna 1A as described in the modification (2) above. The same applies to directivity control only for reception.

  Furthermore, the antennas 1A, 1B, and 1C having a transmission / reception function are not limited to the antennas, and at least one of them may be replaced with a transmission-dedicated antenna or a reception-dedicated antenna.

(4) Staggered arrangement of interrogators In the above embodiment, as conceptually shown in FIG. 5, a plurality of interrogators 100 are arranged on a substantially straight line, for example (as an example, along the movement path of the wireless tag T). Although it arrange | positioned along one side, such as a corridor, it is not restricted to this, You may arrange | position in another aspect, for example, zigzag form.

  FIG. 10 is a diagram showing a modified example of such a staggered arrangement. Interrogators 100L, 100L,... Arranged on the left side of the moving path of the RFID tag T, and interrogators 100R, 100R,. Are arranged in a staggered pattern alternately on both sides like an interrogator 100R, an interrogator 100L, an interrogator 100R, an interrogator 100L,...

  By adopting such a substantially staggered arrangement, for example, the left interrogators 100L, 100L,... And the right interrogators 100R, 100R,. Therefore, the number of necessary interrogators is further reduced, and more efficient movement detection without waste is possible.

  Further, in each of the interrogators 100L and 100R, the beam position at the detection range limit (in the above example, the movement path end point side of the wireless tag T) matches the direction in which the adjacent interrogator is located. There is also an effect that it is convenient when performing a movement notification (tracking succession request notification).

(5) Simultaneous detection of multiple tags Applying the wide and narrow changes in directivity described in (2) above and the functional modification of the antenna described in (3) above, for example, to broaden the directivity of the transmitting antenna (broad). Thus, if the directivity of the receiving antenna is made narrow (sharp) and a plurality of directivities are switched and set, the movement of the plurality of RFID tags T can be tracked at once. In this case, the moving direction is detected for each of the plurality of RFID tags T at predetermined time intervals, and each received signal from the receiving antenna is digitized and stored in a memory to perform parallel processing. This makes it possible to collectively manage the movement of a plurality of wireless tags T.

(6) Others (a) Microvibration control of directivity angle In other words, when changing directivity, (θ ± dθ) detection output is obtained while finely swinging θ at a very small angle at each directivity angle θ. Compare. By doing in this way, the moving direction can be determined in a short time, and the moving direction can always be detected.
(B) Notification timing In the above embodiment, during tracking of the RFID tag T in each interrogator 100, when the directivity angle θ reaches the tracking limit (when θ> θe or when θ <θs) The interrogator 100 adjacent to the end point side or the start point side is notified, but the present invention is not limited to this. For example, the notification may be performed at an appropriate timing during tracking slightly before. Further, the movement of the wireless tag T is very monotonous according to the movement mode of the wireless tag T being tracked at that time (for example, when the movement speed of the wireless tag T is relatively fast and high detection accuracy is not required). If it is known, for example, the next interrogator 100 may be notified instead of the adjacent interrogator 100. In short, it is sufficient to output a notification signal to another interrogator located on the front side in the moving direction of the wireless tag T.
(C) Extensibility to wireless tag that does not generate access information In the above, the signal processing circuit 3 generates access information for accessing the wireless tag information of the IC circuit unit 150 of the wireless tag circuit element To, and Although the case where the transmission unit 212 of the circuit 2 transmits the generated access information (protocol) to the RFID circuit element To without contact is described as an example, the present invention is not limited thereto. That is, the present invention can also be applied to a RFID circuit element that responds only by transmitting a carrier wave from an interrogator without using the above access information, such as a very small RFID circuit element (so-called mu chip). The same effect is obtained. That is, in the interrogator of the present invention, it is sufficient that the transmission unit has a function of transmitting at least a carrier wave.

  In addition, although not illustrated one by one, the present invention is implemented with various modifications within a range not departing from the gist thereof.

  It is assumed that the “Scroll All ID” signal, “Erase” signal, “Verify” signal, and “Program” signal used above conform to the Auto-IDClass I specification established by EPC global. EPC global is a non-profit corporation established jointly by the International EAN Association, which is an international organization of distribution codes, and the United Code Code Council (UCC), which is an American distribution code organization. Note that signals conforming to other standards may be used as long as they perform the same function.

1 is a system configuration diagram illustrating an overall outline of a wireless tag communication system to which an embodiment of the present invention is applied. It is a block diagram showing an example of a functional structure of the radio | wireless tag circuit element with which the radio | wireless tag was equipped. It is a functional block diagram showing the functional structure of the high frequency circuit with which the interrogator shown in FIG. 1 was equipped. It is explanatory drawing which represents notionally the detection behavior of the moving direction of the wireless tag by the interrogator shown in FIG. It is explanatory drawing which represents notionally the movement tracking behavior of the wireless tag by a several interrogator. It is a flowchart showing the control procedure which the control circuit of one interrogator performs in order to perform directivity switching control. It is a flowchart showing the control procedure which the control circuit of one interrogator performs in order to perform directivity switching control. It is a flowchart showing the detailed procedure of step S100 shown in FIG. 6 or FIG. It is a figure showing an example of directivity control in the modification which changes the breadth of directivity itself. It is a figure showing the modification which arranged the interrogator in zigzag form.

1 Array antenna 1A Antenna element (transmitting / receiving antenna element, transmitting antenna element, receiving antenna element)
1B Antenna element (transmitting / receiving antenna element, transmitting antenna element, receiving antenna element)
1C Antenna element (transmitting / receiving antenna element, transmitting antenna element, receiving antenna element)
4 Control circuit (switching control means, moving direction detection means; directivity control means; notification signal output means)
DESCRIPTION OF SYMBOLS 100 Interrogator 100L Interrogator 100R Interrogator 150 IC circuit part 211 Directivity control part (direction switching means, moving direction detection means)
212 Transmitter (information transmission means)
213 Receiving unit (information receiving means)
S RFID tag communication system T RFID tag To RFID tag circuit element

Claims (14)

An antenna composed of a plurality of antenna elements for performing non-contact information communication with the IC circuit portion of the RFID tag circuit element to be interrogated;
Information transmitting means for transmitting at least a carrier wave to the RFID tag circuit element in a non-contact manner via the antenna and performing access;
Information receiving means for receiving, in a non-contact manner, a response signal returned from the IC circuit unit according to the carrier wave transmitted by the information transmitting means;
A moving direction for controlling the direction of directivity by the antenna composed of the plurality of antenna elements and detecting the moving direction of the RFID circuit element according to the result of communication with the IC circuit unit in the at least two directivity directions Detecting means,
The moving direction detecting means is
Direction switching means capable of switching the direction of directivity by the antenna;
Switching control means for controlling the direction switching means so as to sequentially change the direction while holding the antenna directivity strong in only one direction,
The switching control means includes
After the normal response signal is obtained by the information receiving means in one directivity direction of the antenna, when the magnitude of the reception output of the response signal becomes less than a predetermined threshold, the wireless tag Control the direction switching means to follow the moving direction of the circuit element to switch the antenna to another directivity direction ,
And,
In accordance with the directionality of the antenna to be switched by the direction switching means, a directivity control means for changing the directionality of the antenna is provided.
The directivity control means includes
After the normal response signal is obtained by the information receiving means in a certain directivity direction with a wide width, the magnitude of the reception output of the response signal that can be received with the directivity by the movement of the RFID circuit element is The interrogator of the RFID tag communication system , wherein the width direction range of the directivity of the antenna is reduced when it becomes less than a predetermined threshold value . The interrogator of the RFID tag communication system according to claim 1,
The switching control means includes
After the normal response signal is obtained by the information receiving means in one directivity direction of the antenna, when the magnitude of the reception output of the response signal is equal to or greater than the predetermined threshold value, An interrogator for an RFID tag communication system, wherein the direction switching means is controlled to maintain a directivity direction. An antenna composed of a plurality of antenna elements for performing non-contact information communication with the IC circuit portion of the RFID tag circuit element to be interrogated;
Information transmitting means for transmitting at least a carrier wave to the RFID tag circuit element in a non-contact manner via the antenna and performing access;
Information receiving means for receiving, in a non-contact manner, a response signal returned from the IC circuit unit according to the carrier wave transmitted by the information transmitting means;
A moving direction for controlling the direction of directivity by the antenna composed of the plurality of antenna elements and detecting the moving direction of the RFID circuit element according to the result of communication with the IC circuit unit in the at least two directivity directions Detecting means,
The moving direction detecting means is
Direction switching means capable of switching the direction of directivity by the antenna;
Switching control means for controlling the direction switching means so as to sequentially change the direction while holding the antenna directivity strong in only one direction,
The switching control means includes
After the normal response signal is obtained by the information receiving means in one directivity direction of the antenna, the radio signal is demodulated when the error rate when demodulating the response signal becomes larger than a predetermined threshold value. Controlling the direction switching means so as to switch the antenna to another directivity direction following the moving direction of the tag circuit element ,
And,
In accordance with the directionality of the antenna to be switched by the direction switching means, a directivity control means for changing the directionality of the antenna is provided.
The directivity control means includes
Error rate when demodulating the response signal that can be received with the directivity by movement of the RFID circuit element after the normal response signal is obtained by the information receiving means in a certain directivity direction with a wide width The interrogator of the RFID tag communication system , wherein the range of the antenna directivity in the width direction is reduced when becomes larger than a predetermined threshold value . The interrogator of the RFID tag communication system according to claim 3,
The switching control means includes
After the normal response signal is obtained by the information receiving means in one directivity direction of the antenna, the error rate when demodulating the response signal is equal to or less than the predetermined threshold value. The interrogator of the RFID tag communication system, wherein the direction switching means is controlled so as to maintain the directivity direction. The interrogator of the RFID tag communication system according to any one of claims 1 to 4 ,
The antenna includes a plurality of transmitting antenna elements,
The interrogator of the RFID tag communication system, wherein the moving direction detecting means controls a direction of directivity by the plurality of transmitting antenna elements. The interrogator of the RFID tag communication system according to any one of claims 1 to 5 ,
The antenna includes a plurality of receiving antenna elements,
The interrogator of the RFID tag communication system, wherein the moving direction detecting means controls a direction of directivity by the plurality of receiving antenna elements. The interrogator of the RFID tag communication system according to any one of claims 1 to 6 ,
The antenna includes a plurality of antenna elements for transmitting and receiving,
The interrogator of the RFID tag communication system, wherein the moving direction detection means controls the direction of directivity at least in one of transmission and reception by the plurality of antenna elements for transmission and reception. The interrogator of the RFID tag communication system according to any one of claims 1 to 7 ,
The information transmitting unit and the information receiving unit perform information communication with the IC circuit units of the plurality of RFID tag circuit elements via an antenna,
The interrogator of the RFID tag communication system, wherein the moving direction detecting means detects the moving direction at predetermined time intervals for each of the plurality of RFID tag circuit elements. An interrogator provided in a wireless tag communication system having a plurality of interrogators according to claim 1 or 3,
When the moving direction detecting unit cannot detect the moving direction of the RFID circuit element, it has a notification signal output unit that outputs a notification signal to another interrogator adjacent to the moving direction side.
An interrogator for a wireless tag communication system. An antenna composed of a plurality of antenna elements for performing non-contact information communication with the IC circuit portion of the RFID tag circuit element to be interrogated; transmitting at least a carrier wave to the RFID circuit element through the antenna in a non-contact manner and accessing An information transmitting means for receiving the response signal sent back from the IC circuit unit in response to the carrier wave transmitted by the information transmitting means, in a non-contact manner via the antenna ; and from the plurality of antenna elements comprising controlling the directivity by the antenna, according to the communication result between the IC circuit portion in at least two of said directional direction, and a moving direction detection means for detecting a movement direction of the RFID circuit element ,
The moving direction detecting means is
Direction switching means capable of switching the direction of directivity by the antenna;
Switching control means for controlling the direction switching means so as to sequentially change the direction while holding the antenna directivity strong in only one direction;
With
The switching control means includes
After the normal response signal is obtained by the information receiving means in one directivity direction of the antenna, when the magnitude of the reception output of the response signal becomes less than a predetermined threshold, the wireless tag Control the direction switching means to follow the moving direction of the circuit element to switch the antenna to another directivity direction,
And according to the directionality of the antenna to be switched by the direction switching means, there is provided directivity control means for changing the directionality of the antenna, and the directivity control means has a larger width. After the normal response signal is obtained by the information receiving means in the directivity direction, the magnitude of the reception output of the response signal that can be received with the directivity by the movement of the RFID circuit element is a predetermined threshold value. If less than, reduce the width direction range of the antenna directivity;
Interrogator
A RFID tag communication system, wherein a plurality of RFID tag circuit elements that are set or assumed in advance are arranged along a movement path of the RFID tag circuit element. An antenna composed of a plurality of antenna elements for performing non-contact information communication with the IC circuit portion of the RFID tag circuit element to be interrogated; transmitting at least a carrier wave to the RFID circuit element without contact via the antenna An information transmitting means for receiving the response signal sent back from the IC circuit unit in response to the carrier wave transmitted by the information transmitting means, in a non-contact manner via the antenna; and from the plurality of antenna elements And a moving direction detecting means for controlling the direction of directivity by the antenna and detecting the moving direction of the RFID circuit element according to the result of communication with the IC circuit unit in the at least two directivity directions. ,
The moving direction detecting means is
Direction switching means capable of switching the direction of directivity by the antenna;
Switching control means for controlling the direction switching means so as to sequentially change the direction while holding the antenna directivity strong in only one direction;
With
The switching control means includes
After the normal response signal is obtained by the information receiving means in one directivity direction of the antenna, the radio signal is demodulated when the error rate when demodulating the response signal becomes larger than a predetermined threshold value. Controlling the direction switching means so as to switch the antenna to another directivity direction following the moving direction of the tag circuit element,
And according to the directionality of the antenna to be switched by the direction switching means, there is provided directivity control means for changing the directionality of the antenna, and the directivity control means has a larger width. After the normal response signal is obtained by the information receiving means in the directivity direction, the error rate when the response signal that can be received with the directivity is demodulated by the movement of the RFID circuit element is a predetermined threshold. If greater than the value, reduce the width direction range of the antenna directivity;
Interrogator
A RFID tag communication system, wherein a plurality of RFID tag circuit elements that are set or assumed in advance are arranged along a movement path of the RFID tag circuit element. The wireless tag communication system according to claim 10 or 11 ,
Each of the plurality of interrogators outputs a notification signal to another interrogator located on the moving direction side at a predetermined timing when the moving direction detecting means detects the moving direction of the RFID circuit element. A wireless tag communication system comprising a notification signal output means. The wireless tag communication system according to claim 12 ,
The notification signal output means outputs a notification signal to the other interrogator adjacent to the moving direction side when the moving direction detecting means cannot detect the moving direction of the RFID circuit element. A wireless tag communication system. The wireless tag communication system according to any one of claims 10 to 13 ,
The RFID tag communication system, wherein the plurality of interrogators are alternately arranged in a staggered pattern on both sides of the moving route along the moving route.

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