JP2011205287A - Radio tag position detection system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a configuration that enables a radio tag position detection system for detecting the position of a radio tag using a plurality of base stations to suppress the occurrence of interference and to perform position detection more in real time.SOLUTION: The radio tag position detection system 1 includes a radio tag 50 and the plurality of base stations 60 capable of communicating with the radio tag 50 by radio. Then the radio tag 50 is provided with a tag-side receiver for receiving a radiowave from a base station 60, a radiowave intensity detection unit for detecting the radiowave intensity of the radiowave from the base station 60, a base station selection unit for selecting a base station 60 to which a response radiowave is to be transmitted according to radiowave intensities of radiowaves detected by the radiowave intensity detection unit when the radiowaves are received from a plurality of base stations, and a tag-side transmission unit for transmitting the response radiowave to the base station 60 selected by the base selection unit.

Description

  The present invention relates to a wireless tag position detection system.

  In recent years, a wireless tag system that performs wireless communication using a wireless tag has been widely provided, and a technique for detecting the position of the wireless tag has been devised. As an example, for example, a plurality of base stations that can wirelessly communicate with a wireless tag are provided in the communication target area, and by specifying a base station that communicates with the wireless tag, in which area the wireless tag is located. Techniques such as detection are provided.

JP 2006-340048 A

  In the wireless tag position detection system as described above, it is required to detect the position of the wireless tag to be detected in real time and with higher accuracy. However, a plurality of wireless tags perform wireless communication with the base station at the same time. When it is performed, interference is likely to occur, and as a result, there is a problem that the detection accuracy of the wireless tag is lowered.

  On the other hand, as a technique for suppressing such interference, Patent Document 1 is also provided. In this technology, the response cycle of the wireless tag is made different between an area with a high security level and an area with a low security level, and the probability of signal collision is reduced by extending the response cycle in an area with a low security level. . However, with this technique, there is a concern that interference is not sufficiently suppressed, and there is a problem that the real-time property of position detection is lost in an area where a long response cycle is set.

  The present invention has been made in order to solve the above-described problems, and in a wireless tag position detection system that detects the position of a wireless tag using a plurality of base stations, the occurrence of interference can be suppressed and the position can be reduced. It aims at providing the structure which can detect more in real time.

  The invention of claim 1 includes one or more wireless tags capable of transmitting and receiving radio waves, base station side transmitting means for transmitting radio waves to the radio tag, and base station side receiving means for receiving radio waves from the radio tag. A wireless tag position detection system comprising: a plurality of base stations that perform wireless communication with the wireless tag through radio waves, wherein the wireless tag receives radio waves from the base station side transmitting means Tag side receiving means, radio wave intensity detecting means for detecting radio wave intensity from the base station received by the tag side receiving means, and the tag side receiving means for receiving radio waves from the plurality of base stations, respectively. Base station selection means for selecting a base station that transmits a response radio wave based on the radio field intensity of each radio wave detected by the radio field intensity detection means when received, and selected by the base station selection means. It is characterized by comprising: a tag-side transmission means for transmitting the response radio wave to the base station has.

  According to a second aspect of the present invention, in the wireless tag position detection system according to the first aspect, the base station transmits its base station ID to the wireless tag by the base station side transmission means via radio waves. The tag-side receiving means receives the radio wave including the base station ID from the base station-side transmitting means, and the tag-side transmitting means is the base station of the base station selected by the base station selecting means. The station ID is transmitted to the base station via the response radio wave.

  According to a third aspect of the present invention, in the wireless tag position detection system according to the first or second aspect, the base station selection unit periodically acquires the detection result of the radio field intensity by the radio field intensity detection unit. If the base station selected by the base station selecting means is the same as the base station previously selected by the base station selecting means, the tag side A transmitting means does not transmit the response radio wave to the base station.

  According to a fourth aspect of the present invention, in the wireless tag position detection system according to any one of the first to third aspects, a management device capable of communicating with a plurality of the base stations is further provided. A base station specifying unit that periodically specifies the base station that receives the response radio wave from the radio tag, and the base station that receives the response radio wave of the radio tag specified by the base station specifying unit And notifying means for notifying when the relationship between the wireless tag and the base station specified last time by the base station specifying means is a predetermined abnormal relationship.

  According to a fifth aspect of the present invention, in the wireless tag position detection system according to the fourth aspect, the notification means is capable of transmitting predetermined notification information to the wireless tag, and the wireless tag includes the management When the predetermined notification information is received from the notification means of the apparatus, a tag-side notification means for notifying the holder of the wireless tag is provided.

According to the first aspect of the present invention, in the wireless tag position detection system comprising one or more wireless tags capable of transmitting and receiving radio waves and a plurality of base stations that perform wireless communication with the wireless tags, the wireless tag is connected to the base station side. Tag side receiving means for receiving radio waves from the transmitting means, radio wave intensity detecting means for detecting radio wave intensity from the base station received by the tag side receiving means, and tag side receiving means from a plurality of base stations A base station selecting means for selecting a base station that transmits a response radio wave based on the radio wave intensity of each radio wave detected by the radio wave intensity detecting means when receiving each radio wave, and a base station selected by the base station selecting means Tag-side transmission means for transmitting a response radio wave to.
In this way, even if a plurality of base stations can receive response radio waves from the wireless tag, a response is selectively made to one of the base stations. Therefore, the occurrence of interference can be effectively suppressed. In addition, the number of communications and the procedure are not greatly limited to suppress the occurrence of interference, and position detection can be performed in real time.

  In the invention of claim 2, the base station transmits its own base station ID to the wireless tag through the radio wave by the base station side transmission means, and the tag side reception means transmits the base station from the base station side transmission means. The radio wave containing the ID is received, and the tag-side transmission means transmits the base station ID of the base station selected by the base station selection means to the base station via the response radio wave. In this way, the response radio wave can be selectively transmitted to the selected base station without performing complicated transmission timing control. In addition, since there is no need to control the timing greatly when responding to the base station, response radio waves can be transmitted in real time.

  In the invention of claim 3, the base station selection means periodically acquires the result of the detection of the radio wave intensity by the radio wave intensity detection means and periodically selects the base station, and is selected by the base station selection means. When the base station is the same as the base station previously selected by the base station selection means, the tag side transmission means is configured not to transmit response radio waves to the base station. In this way, the position of the wireless tag can be periodically confirmed. Further, when the base station selected by the base station selecting means is the same as the base station selected last time, the response radio wave is transmitted. Since it can be omitted, interference can be further effectively suppressed, and the processing load at the base station and the wireless tag can be effectively reduced. In this case, since the previous detection result can be used for the position detection of the wireless tag, the real-time property of the position detection is not lost.

  In the invention of claim 4, a management device capable of communicating with a plurality of base stations is provided, and the management device periodically specifies a base station that receives a response radio wave from the wireless tag, and a base station Notification that notifies when the relationship between the base station that has received the response radio wave of the wireless tag specified by the specifying means and the base station that was previously specified for the wireless tag by the base station specifying means is a predetermined abnormal relationship Means. In this way, the management device can monitor whether the wireless tag has a predetermined abnormal relationship with a plurality of base stations. When the abnormal relationship is detected, the wireless tag is notified to prompt an appropriate response. be able to.

  In the invention of claim 5, the notification means can transmit predetermined notification information to the wireless tag, and when the wireless tag receives the predetermined notification information from the notification means of the management apparatus, Tag-side notifying means for notifying the owner of the wireless tag is provided. If it does in this way, it will become possible to grasp that a wireless tag holder has a predetermined abnormal relation, and it becomes easy for a wireless tag owner to take an appropriate measure.

FIG. 1 is an explanatory diagram schematically illustrating the configuration of the RFID tag position detection system according to the first embodiment. 2A is a block diagram illustrating an electrical configuration of a base station in the wireless tag position detection system of FIG. FIG. 2B is a block diagram illustrating an electrical configuration of the management device in the wireless tag position detection system of FIG. FIG. 3 is a block diagram illustrating an electrical configuration of a wireless tag used in the wireless tag position detection system of FIG. FIG. 4 is a timing chart schematically showing the radio wave transmission time from each base station and the response radio wave transmission time from each wireless tag. FIG. 5 is a flowchart illustrating the flow of response processing performed by the wireless tag. 6A is an explanatory diagram illustrating a frame configuration of data transmitted from the base station to the radio tag, and FIG. 6B is an explanatory diagram illustrating a frame configuration of data transmitted from the radio tag to the base station. FIG.

[First embodiment]
Hereinafter, a first embodiment in which a wireless tag position detection system of the present invention is embodied will be described with reference to the drawings.
(Overall configuration of wireless tag position detection system)
First, the RFID tag position detection system according to the first embodiment will be outlined with reference to FIGS. FIG. 1 is an explanatory diagram schematically illustrating the configuration of the RFID tag position detection system according to the first embodiment. 2A is a block diagram illustrating an electrical configuration of a base station in the wireless tag position detection system of FIG. FIG. 2B is a block diagram illustrating an electrical configuration of the management device in the wireless tag position detection system of FIG. FIG. 3 is a block diagram illustrating an electrical configuration of a wireless tag used in the wireless tag position detection system of FIG.

  A wireless tag position detection system (hereinafter also referred to as a position detection system) 1 shown in FIG. 1 is configured as a system capable of detecting the position of the wireless tag 50, and is mainly capable of transmitting and receiving radio waves to and from the management device 80. Alternatively, a plurality of wireless tags 50 and a plurality of base stations 60 that perform wireless communication with the wireless tags 50 through radio waves are provided, and wireless communication is performed by specifying which base station the wireless tag 50 is communicating with. The position of the tag 50 is detected. First, the hardware configuration of each of these elements will be described.

  The base station 60 is connected to the management device 80 and is configured to perform wireless communication with the wireless tag 50 in the communication area. As shown in FIG. 2A, the base station 60 includes a control circuit 61 that controls the entire control. The control circuit 61 includes a wireless communication unit 65, a memory 67, an input unit 68, and a communication interface 69. Etc. are connected.

  The control circuit 61 is composed mainly of a microcomputer, for example, has a CPU, a system bus, an input / output interface, and the like, and functions as an information processing device together with the memory 67. The memory 67 is configured as a semiconductor memory such as a ROM or a RAM, and stores various information. The input unit 68 includes operation buttons and the like, and is configured to give a signal corresponding to an external operation to the control circuit 61. The communication interface 69 is configured as an interface (for example, a LAN interface) for performing communication with an external device (for example, the management device 80), and has a configuration for performing communication processing in cooperation with the control circuit 61. There is no.

  The wireless communication unit 65 functions as a known wireless tag reader, and performs communication by electromagnetic waves with the wireless tag 50 in cooperation with the control circuit 61 to read data stored in the wireless tag 50, or It functions to write data to the wireless tag 50. The wireless communication unit 65 is configured as a circuit that performs transmission using a known radio wave system, and includes a transmission circuit 62, a reception circuit 63, and the like as illustrated in FIG.

  The transmission circuit 62 includes a carrier oscillator, an encoding unit, an amplifier, a transmission unit filter, a modulation unit, and the like, and is configured to output a carrier (carrier wave) having a predetermined frequency from the carrier oscillator. The encoding unit is connected to the control circuit 61, encodes transmission data output from the control circuit 61, and outputs the encoded transmission data to the modulation unit. The modulation unit is a part to which the carrier (carrier wave) from the carrier oscillator and the transmission data from the encoding unit are input. The carrier (carrier wave) output from the carrier oscillator is encoded at the time of command transmission to the communication target. A modulated signal that is PSK (Phase Shift Keying) modulated by the encoded transmission code (modulated signal) output from the encoding unit is generated and output to the amplifier. The amplifier amplifies the input signal (the modulated signal modulated by the modulation unit) with a predetermined gain, and outputs the amplified signal to the transmission unit filter. The transmission unit filter filters the amplified signal from the amplifier. A transmission signal is output to the antenna 64. When a transmission signal is output to the antenna 64 in this way, the transmission signal is radiated to the outside from the antenna 64 as an electromagnetic wave.

  On the other hand, the radio wave signal received by the antenna 64 is input to the receiving circuit 63. The reception circuit 63 is configured by a reception unit filter, an amplifier, a demodulation unit, a binarization processing unit, a decoding unit, and the like, and after filtering a signal received via the antenna 64 with a reception unit filter, The signal is amplified by an amplifier, and the amplified signal is demodulated by a demodulator. Then, the demodulated signal waveform is binarized by the binarization processing unit and decoded by the decoding unit, and then the decoded signal is output to the control circuit 61 as reception data.

  In the present embodiment, a plurality of base stations 60 configured as described above are provided (first base station 60a, second base station 60b, and third base station 60c), and the communication area (with the wireless tag) of each base station. The update area is partially overlapped.

  The management device 80 is configured as a computer, for example, and includes a CPU 81, a storage unit 82, an input unit 83, a communication interface 84, a display unit 85, and the like as shown in FIG. The CPU 81 is responsible for overall control of the management device 80 and is configured to perform various types of information processing based on various programs stored in the storage unit 82.

  The input unit 83 is configured by an input device such as a mouse or a keyboard, and is configured to input a signal corresponding to an external operation to the CPU 81. The communication interface 84 is configured as an interface (for example, a LAN interface) for communicating with an external device (for example, the base station 60), and has a configuration for performing communication processing in cooperation with the CPU 81. The display unit 85 is configured by a liquid crystal display, for example, and has a configuration for displaying various information under the control of the CPU 81.

  In the present embodiment, a plurality of base stations 60 are connected to the management apparatus 80, and information transmission (for example, transmission of control signals) is performed from the management apparatus 80 to each base station 60. Information from the base station 60 (such as data of the reading result of the wireless tag 50) can be received by the management device 80.

  Next, the wireless tag 50 will be described. The wireless tag 50 is configured as a known active tag, for example, and includes a battery (not shown), and performs various operations by receiving power from the battery. As shown in FIG. 3, the wireless tag 50 includes a CPU 51, a transmission circuit 52, a reception circuit 53, a power measurement circuit 54, an antenna 55, a memory 56, and the like.

  The CPU 51 controls the entire wireless tag 50, and performs various information processing such as data output to the transmission circuit 52 and data acquisition from the reception circuit 53. For example, the transmission circuit 52 is configured to load-modulate a carrier signal with transmission data from the CPU 51 and transmit this from the antenna 55 as a radio wave signal. The reception circuit 53 includes a demodulation circuit and the like, demodulates the data superimposed on the transmission signal (carrier signal), and outputs it to the control circuit.

  The memory 56 is composed of various semiconductor memories such as a ROM and an EEPROM, and includes a control program, tag identification information (tag ID) for identifying the wireless tag 50, and data set by the user according to the use of the wireless tag 50. Etc. are stored. The power measurement circuit 54 is configured as a circuit that detects the power of radio waves received from the antenna 55 (radio waves from the base station 60), and is configured to input the detected power value to the CPU 51.

(Wireless tag position detection processing)
Next, wireless tag position detection processing for detecting the position of the wireless tag 50 will be described.
FIG. 4 is a timing chart schematically showing the radio wave transmission time from each base station and the response radio wave transmission time from each wireless tag. FIG. 5 is a flowchart illustrating the flow of response processing performed by the wireless tag. 6A is an explanatory diagram illustrating a frame configuration of data transmitted from the base station to the radio tag, and FIG. 6B is an explanatory diagram illustrating a frame configuration of data transmitted from the radio tag to the base station. FIG.

1. First, transmission processing from the base station will be described.
In the present embodiment, as shown at time 1 and time 3 in FIG. 4, request data (request signal) for requesting a response to the wireless tag 50 is periodically transmitted from each base station. The request data has, for example, a frame structure as shown in FIG. 6A, and includes at least a command code of a predetermined command (a command for requesting a response to the wireless tag) and a base from which the request data is transmitted. The station ID is included. As a result, the base station from which the request data is obtained can be identified on the wireless tag 50 side that acquires the request data.

  Further, as shown in time 1 of FIG. 4, each base station transmits request data (request signal) with a time difference so that the transmission time of request data does not overlap with other base stations. Then, the request data from the second base station is transmitted after the transmission of the request data from the first base station is completed, and the request data from the third base station is transmitted after the transmission of the request data from the second base station is completed. It has become.

  Note that the transmission timing between the base stations can be controlled by, for example, the management device 80. In this case, a transmission command may be given from the management device 80 to each base station 60 with a time difference. In addition, each base station 60 may acquire transmission end data from another base station 60. For example, when transmission end data is sent from the first base station 60a to the second base station 60b. When request data from the second base station 60b is transmitted and transmission end data is transmitted from the second base station 60b to the third base station 60c, the request data from the third base station 60c is transmitted. Also good.

In this embodiment, after the time difference between the plurality of base stations 60 at time 1 as described above, the time difference transmission similar to the case of time 1 is performed at time 3 after a certain time has elapsed. It has become. Such time difference transmission is repeated at regular intervals.
In the present embodiment, the control circuit 61, the transmission circuit 62, and the antenna 64 of the base station 60 correspond to an example of “base station side transmission means”, and request data including its own base station ID is transmitted through radio waves. It functions so as to transmit to the wireless tag 50.

2. Next, response processing performed by the wireless tag 50 will be described.
This process is started when a predetermined start condition is satisfied (for example, when a carrier is detected from the base station), and first the operation is stopped (S1). At this time, power is not supplied to each circuit such as the transmission circuit and the reception circuit. Thereafter, it is determined whether or not the operation stop state has passed for a certain time (for example, 5 seconds) (S2). If the predetermined period has elapsed, the process proceeds to Yes in S2, cancels the operation stop state, enters the reception standby state, and accepts transmission from the base station 60 (S3).

  After S3, it is determined whether or not the above-mentioned request data (request signal: FIG. 6A) has been acquired from any of the base stations 60 (S4). If the request data has not been transmitted from any base station 60, the process proceeds to No in S4, and the transmission acceptance process in S3 is repeated. On the other hand, when the request data is transmitted from any of the base stations 60 and the wireless tag 50 performing the processing of FIG. 5 receives the request data, the process proceeds to Yes in S4, and the request data is transmitted. The radio wave intensity of the radio wave transmitted from the base station 60 is detected and stored in the memory 56 (S5). The detection of the radio wave intensity at S5 is performed by acquiring the detection value of the power measurement circuit 54.

  In the present embodiment, the receiving circuit 53 and the CPU 51 of the wireless tag 50 correspond to an example of “tag side receiving means” and function to receive radio waves including the base station ID from the base station side transmitting means. The power measurement circuit 54 corresponds to an example of a “radio wave intensity detecting unit” and functions to detect the radio wave intensity of the radio wave from the base station 60 received by the tag side receiving unit.

  After S5, it is determined whether or not a predetermined reception time (for example, 500 ms) has elapsed since proceeding to Yes in S2 (that is, whether or not a certain time has elapsed since the operation stop was canceled) ( S6) If it has not elapsed, the process proceeds to No in S6 and repeats the processes of S3 to S6. On the other hand, if the reception time has elapsed, the process proceeds to Yes in S6.

  When the process proceeds to No in S6, the reception state is set again in S3. If request data is transmitted from another base station 60 other than the previously received base station 60, the request data is received (S4: Yes), and the radio wave intensity of the received radio wave is detected and stored in the memory 56. (S5). The process of S5 is as described above.

  As described above, the processes in S3 to S6 are repeated until it is determined in S6 that the reception time has elapsed. Therefore, the radio waves (including request data) from each base station 60 transmitted with a time difference as shown in FIG. Multiple radio waves) may be received. When radio waves from a plurality of base stations 60 are received with a time difference in this way, the radio wave intensity detected at S5 at the time of each reception (the radio wave intensity from each base station) is stored in the memory 56, respectively. Become.

  On the other hand, if it is determined in S6 that the reception time has elapsed, the process proceeds to Yes in S6, and one or more radio waves stored in the memory 56 in the process of S5 in a series of loops of S3 to S6. The maximum radio field intensity is obtained from the intensities, and the base station that has transmitted the radio wave having the maximum radio field intensity is selected as a transmission target (S7).

  The CPU 51 that executes the process of S7 corresponds to an example of a “base station selection unit”, and is detected by the radio field intensity detection unit when the tag side reception unit receives radio waves from a plurality of base stations 60, respectively. It functions to select the base station 60 that transmits the response radio wave based on the radio wave intensity of each radio wave. More specifically, the result of the radio wave intensity detection by the radio wave intensity detection means is periodically (in FIG. 5, constant in S2). And every time it is determined that time has elapsed), the base station 60 is periodically selected.

  After selecting the base station 60 to be transmitted in S7, the selected base station 60 determines the previous selection result (that is, the base in the processing of S7 performed last time of the processing of S7 performed most recently). It is determined whether it is the same as the selection result of the station 60). If the base station 60 selected in S7 is not the same as the previous selection result, the process proceeds to No in S8, and response data transmission processing is performed in S9. On the other hand, if the base station 60 selected in S7 is the same as the previous selection result, the process proceeds to Yes in S8, and in this case, the process in S9 is omitted.

  The response data transmitted in the process of S9 has, for example, a frame structure as shown in FIG. 6B, and includes at least a command code of a predetermined command (command for transmitting a response to the base station), It includes the unique ID (tag ID) of the wireless tag 50 that is going to send the response data. As a result, the base station 60 that obtains the response data can identify from which wireless tag 50 the response data is received.

  For example, the header portion includes the ID of the base station selected in S7, and the base station 60 from which the response data is acquired can be designated. Accordingly, the base station side can determine whether the response data is addressed to itself by checking this header part when response data is received from each wireless tag 50. For example, it is possible to take measures such as discarding data.

  In addition, after the process of S9 or when proceeding to Yes in S8, it is determined whether there is a process end command from the base station 60 that transmitted the response data in S9 (S10), and there is a process end command In S10, the process proceeds to Yes, and the response process shown in FIG. On the other hand, if there is no process end command, the process proceeds to No in S10, and the processes after S1 are repeated.

  In the present embodiment, the CPU 51 and the transmission circuit 52 correspond to an example of a “tag side transmission unit”, and function to transmit a response radio wave to the base station 60 selected by the base station selection unit. The base station ID of the base station 60 selected by the base station selecting means functions to transmit to the base station 60 via the response radio wave. Further, when the base station 60 selected by the base station selection means is the same as the base station 60 selected last time by the base station selection means, the response radio wave is not transmitted to the base station 60. It is functioning.

  Since response processing is performed as described above, each wireless tag 50 selects only the base station with the strongest radio wave intensity when receiving request data from one or more base stations 60 in the communicable range. Will be able to return a response.

  Since response processing is performed in each wireless tag 50 in this way, processing is performed in a flow as shown in FIG. 4, for example, in an area where a plurality of base stations 60 and wireless tags 50 exist. In FIG. 4, each base station 60 performs time difference transmission on the request data as described above, and a plurality (three in FIG. 4) of wireless tags 50 (tag A) that can communicate with one or a plurality of these base stations 60. , Tag B, tag C) specifically illustrates the case where the response process as shown in FIG. 5 is performed. In the example of FIG. 4, when the request data is transmitted from each base station 60 (first base station 60 a, second base station 60 b, third base station 60 c) at a time difference at time 1, each wireless tag 50 communicates with each other. Request data from the base station 60 within the possible range is received.

Each wireless tag 50 that has received the request data at time 1 as described above performs the response process of FIG. 5 and selectively transmits response data to the base station 60 selected at time 2. is doing. The transmission of the response data is performed until the next time difference transmission is performed from each base station 60 (that is, between time 1 and time 2). As described above, each base station 60 has its own base station. Response data including the station ID in the header is selected and acquired.
In the present embodiment, the antenna 64, the receiving circuit 63, and the control circuit 61 correspond to an example of “base station side receiving means” and function to receive radio waves from the wireless tag.

  As described above, after response data is transmitted from each wireless tag 50 at time 2 and received at each base station 60, from each base station 60 at time 3 (a time after a fixed time has elapsed from time 1). Time difference transmission is performed again, and each request data transmitted by these time difference transmissions is received by each wireless tag 50. Each wireless tag 50 receives the request data sent at time 3 in the same manner as in time 1, selects the base station 60, and returns response data to the selected base station 60. However, if the selection is the same as the previous selection (selection when response data is sent at time 2), transmission of response data is omitted.

  For example, tag A illustrates a case where the base station 60 to which response data is to be transmitted when request data is received from each base station 60 at time 3 is selected as the first base station 60a. Sending response data is omitted. On the other hand, for example, in the tag B, the case where the base station 60 to which the response data is to be transmitted when the request data is received from each base station 60 at the time 3 is illustrated as the first base station 60a. Since it has changed from the selected second base station 60b, response data is transmitted to the changed first base station 60a at time 4.

In the present embodiment, each time the time difference transmission described above is performed, the tag ID of the wireless tag 50 that can communicate with each base station 60 (the wireless tag 50 that selects each base station 60 and returns response data) can be detected. Thus, it is possible to more accurately detect which wireless tag 50 exists in which base station 60 area (more specifically, which base station 60 each wireless tag 50 is closer to). In addition, the management device 80 receives the reading result of the wireless tag 50 read by each base station 60 for each time difference transmission from each base station 60, and periodically transmits the position (each of each wireless tag 50 for each time difference transmission). It is possible to detect which base station 60 the wireless tag 50 is closer to.
The CPU 81 of the management device 80 corresponds to an example of “base station specifying means” and functions to periodically specify the base station 60 that receives the response radio wave from the wireless tag 50.

(Main effects of the first embodiment)
In the wireless tag position detection system 1 according to the first embodiment, the wireless tag 50 includes a tag-side receiving unit that receives a radio wave from the base station-side transmitting unit, and a radio wave from the base station 60 that is received by the tag-side receiving unit. Radio wave intensity detecting means for detecting the radio wave intensity and the tag-side receiving means when receiving radio waves from the plurality of base stations 60 respectively, the response radio wave based on the radio wave intensity of each radio wave detected by the radio wave intensity detecting means Base station selection means for selecting a base station 60 for transmitting the signal, and tag side transmission means for transmitting a response radio wave to the base station 60 selected by the base station selection means.
In this way, even if the response radio waves from the wireless tag 50 can be received by the plurality of base stations 60, a response is selectively made to any of the base stations 60. Therefore, the occurrence of interference can be effectively suppressed. In addition, the number of communications and the procedure are not greatly limited to suppress the occurrence of interference, and position detection can be performed in real time.

  Further, in the present embodiment, the base station 60 transmits its own base station ID to the wireless tag 50 through the radio wave by the base station side transmission means. The tag side receiving means receives the radio wave including the base station ID from the base station side transmitting means, and the tag side transmitting means returns the base station ID of the base station 60 selected by the base station selecting means as a response. It transmits to the base station 60 through radio waves. In this way, the response radio wave can be selectively transmitted to the selected base station 60 without performing complicated transmission timing control. In addition, since there is no need to control the timing greatly when responding to the base station 60, the response radio wave can be transmitted in real time.

In this embodiment, the base station selection means periodically acquires the result of the radio field intensity detection by the radio field intensity detection means and periodically selects the base station 60, and is selected by the base station selection means. When the base station 60 is the same as the base station 60 selected last time by the base station selection means, the tag side transmission means does not transmit a response radio wave to the base station 60.
In this way, the position of the wireless tag 50 can be periodically confirmed. Further, when the base station 60 selected by the base station selecting means is the same as the previously selected base station 60, the response radio wave Therefore, the interference can be further effectively suppressed, and the processing load on the base station 60 and the wireless tag 50 can be effectively reduced. In this case, since the previous detection result can be used for the position detection of the wireless tag 50, the real-time property of the position detection is not lost.

[Other Embodiments]
The present invention is not limited to the embodiments described with reference to the above description and drawings. For example, the following embodiments are also included in the technical scope of the present invention.

In the above embodiment, the management device 80 is provided with base station specifying means for periodically specifying the base station 60 (the base station estimated to be closest to each wireless tag) that receives response radio waves from each wireless tag. Although an example is shown, the base station 60 close to each wireless tag is periodically specified by the management device 80 in this way, and further, the base station that has received the response radio wave of any wireless tag 50 60 and when the relationship between the wireless tag 50 and the base station 60 previously specified by the base station specifying means is a predetermined abnormal relationship, this is determined and notified by the display unit 85 or the like (for example, an abnormality is indicated) Displaying explanation information) may be performed. In this case, the CPU 81 and the display unit 85 correspond to an example of “notification means”. Note that the notification example is not limited to this, and may be voice notification by a buzzer or the like, or may be a method in which notification information is transmitted to a device that can communicate with the management device 80.
As the “predetermined abnormal relationship”, for example, “when the base station specified last time and the base station specified this time are at a predetermined long distance (for example, the base station specified this time was specified last time) Various conditions such as “when the base station other than the base station adjacent to the base station is present” or “when the base station specified last time does not exist and a new base station is specified this time” can be used as conditions. .
In this way, the management device 80 can monitor that the wireless tag 50 has a predetermined abnormal relationship with the plurality of base stations 60, and when the abnormal relationship is detected, a notification is given and an appropriate relationship is established. Response can be encouraged.
In addition, the “notification unit” (CPU 81) of the management device 80 provides the base station 60 with respect to the wireless tag 50 to be notified (the wireless tag 50 determined to have a predetermined abnormal relationship as described above). A configuration may be used in which predetermined notification information (for example, a predetermined notification command) is transmitted through the network. In this case, the management device 50 transmits the wireless tag 50 together with the tag ID of the wireless tag 50 to the base station 60 in communication with the wireless tag 50 (wireless tag 50 determined to have a predetermined abnormal relationship as described above). An instruction to transmit predetermined notification information is given to the wireless tag 50, and a tag ID designating the wireless tag 50 and the predetermined notification information are transmitted from the base station 60 to the wireless tag 50. do it. When the wireless tag 50 receives predetermined notification information (for example, a predetermined notification command) from the “notification unit” of the management device 60, the wireless tag 50 sounds a buzzer, displays a lamp, and the like. What is necessary is just to alert | report to a holder. In this case, a buzzer and a lamp (not shown) may be provided in the wireless tag 50, and the CPU 51 and the buzzer and the lamp correspond to an example of “tag side notification means”. If it does in this way, it will become possible to grasp that a wireless tag holder has a predetermined abnormal relation, and it becomes easy for a wireless tag owner to take an appropriate measure.

DESCRIPTION OF SYMBOLS 1 ... Wireless tag position detection system 50 ... Wireless tag 51 ... CPU (tag side transmission means, tag side reception means, base station selection means)
52. Transmission circuit (tag side transmission means)
53. Receiving circuit (tag-side receiving means)
54 ... Electric power measurement circuit (radio wave intensity detection means)
60 ... base station 61 ... control circuit (base station side transmission means, base station side reception means)
62 ... Transmission circuit (base station side transmission means)
63. Receiving circuit (base station side receiving means)
64. Antenna (base station side transmission means, base station side reception means)
80 ... management device 81 ... CPU (base station identification means, notification means)
85 ... Display section (notification means)

Claims (5)

One or more wireless tags capable of transmitting and receiving radio waves;
A plurality of base stations that comprise base station side transmitting means for transmitting radio waves to the radio tag and base station side receiving means for receiving radio waves from the radio tag, and that perform radio communication with the radio tag via radio waves When,
A wireless tag position detection system comprising:
The wireless tag is
Tag-side receiving means for receiving radio waves from the base station-side transmitting means;
Radio wave intensity detecting means for detecting the radio wave intensity of the radio wave from the base station received by the tag side receiving means;
A base that selects a base station that transmits a response radio wave based on the radio wave intensity of each radio wave detected by the radio wave intensity detection unit when the tag-side receiving unit receives radio waves from the plurality of base stations. Station selection means,
Tag-side transmission means for transmitting the response radio wave to the base station selected by the base station selection means;
A wireless tag position detection system comprising: The base station transmits its own base station ID to the wireless tag through radio waves by the base station side transmission means,
The tag side receiving means receives a radio wave including the base station ID from the base station side transmitting means,
2. The radio according to claim 1, wherein the tag side transmitting unit transmits the base station ID of the base station selected by the base station selecting unit to the base station through the response radio wave. Tag position detection system. The base station selection means periodically obtains the result of detection of the radio field intensity by the radio field intensity detection means, and periodically selects the base station,
When the base station selected by the base station selecting means is the same as the base station selected last time by the base station selecting means, the tag side transmitting means transmits the response radio wave to the base station. The wireless tag position detection system according to claim 1 or 2, wherein transmission is not performed. A management device capable of communicating with a plurality of the base stations,
The management device
Base station specifying means for periodically specifying the base station that receives the response radio wave from the wireless tag;
The relationship between the base station that has received the response radio wave of the wireless tag specified by the base station specifying means and the base station that was previously specified by the base station specifying means for the wireless tag is a predetermined abnormal relationship An informing means for informing when there is
4. The wireless tag position detection system according to claim 1, further comprising: The notification means can transmit predetermined notification information to the wireless tag,
5. The wireless tag includes a tag-side notification unit that notifies a holder of the wireless tag when the predetermined notification information is received from the notification unit of the management device. The wireless tag position detection system described.

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