Wireless tag communication device and program

Abstract

To provide a radio tag communication device and a program capable of efficiently specifying a position where a radio tag exists.SOLUTION: A wireless tag communication device according to an embodiment includes a communication device that communicates with a wireless tag, a position detection sensor that detects a position of the communication device, a storage unit that stores a reading result in which the position detected by the position detection sensor and a phase of a radio wave received by the communication device from the wireless tag at the position are associated with each other, and a processor. The processor derives a relational expression representing a positional relationship between each position of two points and the position of the wireless tag based on the reading results at the positions of the two consecutive points, calculates a plurality of corresponding positions corresponding to the position of the wireless tag by substituting a plurality of parameter values representing a distance to the wireless tag into the relational expression, calculates a straight line passing through the corresponding positions, and specifies an intersection position between the straight line derived based on the positions of the two points forming a pair and the straight line derived based on the positions of the other two points forming a pair as the position of the wireless tag.SELECTED DRAWING: Figure 9

Description

[Technical Field]

[0001] An embodiment of the present invention relates to a radio tag communication device and a program. [Background technology]

[0002] Conventionally, there have been wireless tag communication devices designed to find RFID tags (hereinafter also referred to as wireless tags) located in unspecified locations. The wireless tag communication device communicates with the wireless tag while changing the position and orientation of the antenna through operation by an operator. Conventional wireless tag communication devices estimate the direction in which the wireless tag to be searched for is located based on the communication status with the wireless tag to be searched for, and notify the operator of the direction in which the wireless tag is located by displaying the estimated direction on a display.

[0003] However, while conventional wireless tag communication devices can estimate the direction in which a wireless tag is located, they cannot estimate the location in which the wireless tag is located, and there is room for improvement in searching for wireless tags. Summary of the Invention [Problem to be solved by the invention]

[0004] The problem to be solved by the present invention is to provide a radio tag communication device and a program that can efficiently identify the location of a radio tag. [Means for solving the problem]

[0005] An embodiment of a radio tag communication device comprises a communicator that communicates with a radio tag, a position detection sensor that detects the position of the communicator, a memory unit that stores read results that associate the position detected by the position detection sensor with the phase of the radio waves received by the communicator from the radio tag at that position, and a processor that identifies the position of the radio tag based on the read results at multiple positions stored in the memory unit.The processor derives a relational equation that represents the positional relationship between each of the two consecutive positions and the position of the radio tag based on the read results at two consecutive positions, calculates multiple corresponding positions corresponding to the position of the radio tag by substituting multiple parameter values ​​that represent the distance to the radio tag into the relational equation, calculates a straight line that passes through the corresponding positions based on the multiple corresponding positions, and identifies the intersection position of the straight line derived based on the positions of two pairs of points and the straight line derived based on the positions of the other two pairs of points as the position of the radio tag. [Brief explanation of the drawings]

[0006] [Figure 1] FIG. 1 is a diagram showing an example of the external configuration of a radio tag communication device according to an embodiment. [Figure 2] FIG. 2 is a block diagram schematically showing a first configuration example of a control system in the RFID tag communication device according to the embodiment. [Figure 3] FIG. 3 is a block diagram schematically showing a second configuration example of the control system in the RFID tag communication device according to the embodiment. [Figure 4] FIG. 4 is a diagram for explaining calculation of the direction in which an RFID tag exists according to the embodiment. [Figure 5] FIG. 5 is a diagram for explaining calculation of the position where an RFID tag exists according to the embodiment. [Figure 6] FIG. 6 is a diagram for explaining calculation of the position where an RFID tag exists according to the embodiment. [Figure 7] FIG. 7 is a diagram for explaining calculation of the position where an RFID tag exists according to the embodiment. [Figure 8]FIG. 8 is a diagram illustrating a method for selecting a line for identifying the position of an RFID tag according to the embodiment. [Figure 9] FIG. 9 is a flowchart illustrating an example of a procedure of a first tag position estimation process according to the embodiment. [Figure 10] FIG. 10 is a flowchart illustrating an example of a procedure of the second tag position estimation process according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0007] Hereinafter, a radio frequency tag communication device and a program according to an embodiment will be described with reference to the drawings. The components in the following embodiments include those that can be easily conceived by a person skilled in the art, those that are substantially the same, and those that are within the scope of so-called equivalents. Furthermore, various omissions, substitutions, modifications, and combinations of the components can be made without departing from the spirit of the following embodiments. First, the configuration of a radio frequency tag communication device (which may also be called a radio frequency tag reading device) according to an embodiment will be described.

[0008] Fig. 1 is a diagram showing an example of the external configuration of a radio frequency tag communication device 1 according to an embodiment. The radio frequency tag communication device 1 shown in Fig. 1 is a handheld device that is operated by an operator while being held in his / her hand. The radio frequency tag communication device 1 shown in Fig. 1 is used, for example, as a search device that searches for an RFID tag (wireless tag) 3 or an article to which an RFID tag 3 is attached.

[0009] The radio tag communication device 1 according to the embodiment is a device that communicates with an RFID tag 3. The radio tag communication device 1 is a radio tag reading device that communicates with the RFID tag 3 to read tag information and the like recorded in the RFID tag 3. The radio tag communication device 1 estimates the location of the RFID tag 3 from the reading result of the RFID tag 3. The radio tag communication device 1 displays a guidance screen on a display 14 that shows information related to the estimated location of the RFID tag 3.

[0010] The RFID tag 3 is a wireless communication device that operates using radio waves (output signals) from the RFID tag communication device 1. The RFID tag 3 includes a processor, memory, a communication circuit, an antenna, etc. The RFID tag 3 outputs a response signal including tag information recorded in its own memory in response to a read command from the RFID tag communication device 1. For example, the RFID tag 3 is attached to an item such as a product or a part. The RFID tag 3 attached to the item has tag information including information identifying the item recorded in its internal memory.

[0011] The radio-frequency tag communication device 1 according to the embodiment is operated by an operator. The radio-frequency tag communication device 1 is a device that communicates with a designated RFID tag 3 while moving. For example, the radio-frequency tag communication device 1 is a handheld device that the operator holds in his / her hand and operates while moving. The radio-frequency tag communication device 1 may also be mounted on a mobile object that is operated by the operator.

[0012] The radio-frequency tag communication device 1 according to the embodiment reads the RFID tag 3 attached to an item while changing its position and orientation in response to an operation by an operator. For example, the radio-frequency tag communication device 1 can be used as a search device for searching for items with RFID tags 3 attached within a predetermined area (search range) of a warehouse, a store, etc. The radio-frequency tag communication device 1 as a search device continuously reads the RFID tags 3 to be searched for while changing its position in response to an operation by an operator.

[0013] The radio tag communication device 1 receives a response signal from the RFID tag 3 present within a reading area (reading range) to read tag information recorded in the RFID tag 3. Furthermore, the radio tag communication device 1 also acquires information such as a received signal strength indicator (RSSI) value and a phase value from the response (received) signal from the RFID tag 3. The radio tag communication device 1 stores the tag information, RSSI value, and phase value obtained from the received signal, together with information such as the position and orientation of the radio tag communication device 1, as reading results in the memory 22.

[0014] 1, the radio tag communication device 1 is composed of a reader device (base device) 10 and an information terminal device 13 as a user interface. The reader device 10 may also be provided as the radio tag communication device 1. In this case, the radio tag communication device 1 as the reader device 10 is operated with the information terminal device 13 as an external device set as a user interface.

[0015] The reader device 10 includes a housing in which an RFID tag interface having an antenna and a communication control circuit is installed. In the reader device 10, the antenna is installed so that its directivity is strongest in the direction of arrow a shown in Fig. 1. Here, the direction of arrow a is assumed to be the front (forward) direction of the RFID tag communication device 1. The front direction of the RFID tag communication device 1 is also assumed to be the direction of the antenna.

[0016] The reader device 10 has a control system configuration, which will be described later, as well as a gripping unit 11 and a holding unit 12. The gripping unit 11 is a part that is held by an operator. The holding unit 12 is configured as a jig that holds an information terminal device 13. The holding unit 12 holds the information terminal device 13 so that the display screen of a display 14 of the information terminal device 13 faces the operator holding the gripping unit 11. The operator operates the RF tag communication device 1 by holding the gripping unit 11 with the information terminal device 13 set in the holding unit 12.

[0017] The information terminal device 13 has a display unit 14 and an input unit 15. The display unit 14 and the input unit 15 are, for example, display devices with touch panels. When the information terminal device 13 is set in the holding unit 12 of the reader device 10, the operator can view the screen displayed on the display unit 14. When the information terminal device 13 is set in the holding unit 12 of the reader device 10, the operator inputs operation instructions to the input unit 15.

[0018] The radio tag communication device 1 is operated by an operator and continuously reads the RFID tags 3. For example, the operator changes the position of the radio tag communication device 1 (the position of the device itself) equipped with an antenna by moving while holding the grip part 11. The radio tag communication device 1 repeatedly reads the RFID tags 3 within a reading area set by the orientation of the antenna and the strength of the radio waves output from the antenna while estimating the position of the device itself.

[0019] The radio tag communication device 1 estimates its own position using a self-estimation technique. For example, the radio tag communication device 1 estimates its own position (the position of its own device) using a self-position estimation technique used in AR (Augmented Reality) technology, based on an image captured by a camera of the information terminal device 13 or the reader device 10, information acquired by a sensor mounted on the information terminal device 13 or the reader device 10, etc. However, the technique and configuration used in the radio tag communication device 1 to estimate its own position are not limited to a specific one as long as it can estimate its own position even indoors, etc.

[0020] The radio-frequency tag communication device 1 estimates the position of the RFID tag 3 based on the read result of the RFID tag 3 within a read area that is set by the orientation of the antenna and the strength of the radio waves output from the antenna. For example, the radio-frequency tag communication device 1 stores the read results of the RFID tags 3 that are search targets in multiple read areas that are based on the positions of the radio-frequency tag communication device 1 as the multiple devices have moved, in the memory 22. For example, the radio-frequency tag communication device 1 stores information such as tag information, the position of the radio-frequency tag communication device 1, the antenna orientation, output value, and phase value as the read result of a specific RFID tag 3 in the memory 22. The radio-frequency tag communication device 1 may also store the read area identified from the position of the radio-frequency tag communication device 1, the antenna orientation, output value, and the like as the read result of a specific RFID tag 3 in the memory 22. The procedure for estimating the position of the RFID tag 3 will be described later.

[0021] Next, the configuration of a control system in the RFID tag communication device 1 according to the embodiment will be described.

[0022] Fig. 2 is a block diagram schematically showing a first configuration example of a control system in the radio tag communication device 1 according to the embodiment. In the configuration example shown in Fig. 2, the radio tag communication device 1 has a processor 21, a memory 22, a radio tag communication unit 23, a sensor 24, a communication interface (I / F) 25, a camera 26, a display 14, and an input device 15. As shown in Fig. 2, the radio tag communication device 1 can communicate with an RFID tag 3 via the radio tag communication unit 23.

[0023] The processor 21 controls each unit. The processor 21 includes an arithmetic circuit such as a CPU (Central Processing Unit). The processor 21 executes programs to control each unit and perform various data processing. The processor 21 may also include an internal memory. The processor 21 executes programs stored in the memory 22 or the like to perform various processes.

[0024] The memory 22 includes various types of memory. For example, the memory 22 includes memories such as ROM (Read Only Memory), RAM (Random Access Memory), and NVM (Non-Volatile Memory). ROM is a non-volatile memory that cannot be rewritten. ROM stores programs to be executed by the processor 21. RAM is a volatile memory that temporarily stores data. RAM operates as a working memory or a buffer memory.

[0025] The NVM of the memory 22 is a rewritable nonvolatile memory. The memory 22 stores information such as control information, setting information, and processing results in the NVM. The memory 22 also stores various programs in the NVM for the processor 21 to execute each process described below. For example, the memory 22 stores in the NVM an operation assistance program that outputs information to assist the operator in operating the housing.

[0026] The wireless tag communication unit 23 is a communicator that constitutes an RFID interface that communicates with the RFID tag 3. The wireless tag communication unit 23 is, for example, a communicator that has a communication control circuit and an antenna. Note that the wireless tag communication unit 23 may also be configured as a connection interface that connects to an external antenna.

[0027] In the wireless tag communication unit 23, the communication control circuit includes a control circuit for communicating with the RFID tag 3 via the antenna. The communication control circuit causes the antenna to emit a transmission signal (radio wave) supplied from the processor 21 at a set output value. The antenna outputs the transmission signal supplied from the communication control circuit as a radio wave that can be received by the RFID tag 3. The wireless tag communication unit 23 sets a range (read area, read range) within which the RFID tag 3 can respond based on the orientation of the antenna and the output value of the radio wave output from the antenna. The wireless tag communication unit 23 may also be referred to as a communicator or a communication unit.

[0028] Furthermore, in the RFID tag communication unit 23, the communication control circuit not only outputs a transmission signal to the antenna but also supplies a signal received by the antenna as received data to the processor 21. The communication control circuit receives a response signal from the RFID tag 3 via the antenna, processes the response signal (received signal) received by the antenna, and supplies the signal to the processor 21. For example, the communication control circuit supplies the processor 21 with tag information included in the received signal from the RFID tag 3, an RSSI value indicating the strength of the received signal, and a phase value.

[0029] The sensor (sensor group) 24 detects the movement of the radio tag communication device 1. For example, the sensor 24 is an acceleration sensor, a gyro sensor, or a geomagnetic (azimuth) sensor. The sensor 24 may be configured to include multiple types of sensors. The sensor 24 may also include a position detection sensor that detects the position of the radio tag communication device 1. The sensor 24 is an example of a position detection sensor.

[0030] The communication interface 25 is an interface for communicating with an external device. The communication interface 25 is an interface for communicating with a higher-level device 19 such as a server. The communication interface 25 may be an interface for wired communication or an interface for wireless communication.

[0031] The camera 26 captures images of the surroundings of the radio tag communication device 1. The imaging direction of the camera 26 changes depending on the orientation of the radio tag communication device 1. For example, the imaging direction of the camera 26 may be set to match the orientation of the antenna of the radio tag communication unit 23. The image generated by the camera 26 is used to estimate the position of the radio tag communication device 1 (the position of the device itself). The camera 26 is an example of a position detection sensor. For example, the radio tag communication device 1 estimates its own position (the position of the device itself) based on the image captured by the camera 26 using a self-position estimation method used in AR (augmented reality) technology. Note that the estimation of the self-position is not limited to using the output from the position detection sensor, and may be performed using other methods using output from other devices.

[0032] The display 14 and input device 15 included in the information terminal device 13 are connected to the processor 21 via an internal interface. The display 14 is a device that displays information. For example, the display 14 displays a display screen instructed by the processor 21. The display 14 is realized by, for example, a display device having a display and / or an LED (Light Emitting Diode), etc. The display 14 may also have an audio device such as a buzzer or speaker. Instead of the display 14, the information terminal device 13 may be equipped with an interface that can be connected to an external display device and an external audio device. In this case, the display 14 corresponds to the external display device, the external audio device, etc.

[0033] The input unit 15 is a device for an operator to input operation instructions, etc. The input unit 15 is realized by, for example, hard switches and / or buttons, a touch panel shared with the display unit 14, etc. Note that instead of the input unit 15, an interface connectable to hard switches and / or buttons, a touch panel shared with the display unit 14, etc. may be mounted on the information terminal device 13. The input unit 15 supplies information indicating the content of an instruction given by the operator to the processor 21.

[0034] The radio tag communication device 1 has a power source that supplies power for operation. In a handheld radio tag communication device 1, for example, a rechargeable battery (secondary battery) is provided as the power source. The battery supplies power to each part of the radio tag communication device 1 to operate each part. The radio tag communication device 1 may be configured such that the camera 26 is replaced with a device for identifying the location of the device itself.

[0035] Next, a second configuration of the control system in the RFID tag communication device 1 according to the embodiment will be described.

[0036] Fig. 3 is a block diagram schematically showing a second configuration example of a control system in the radio tag communication device 1 according to the embodiment. In the configuration example shown in Fig. 3, a reader device 10 as the radio tag communication device 1 is connected to an information terminal device 13 as an external device. The reader device 10 as the radio tag communication device 1 has a processor 21, a memory 22, a radio tag communication unit 23, and an interface (I / F) 26.

[0037] The processor 21 controls each unit. The processor 21 includes, for example, an arithmetic circuit such as a CPU. The processor 21 executes programs to control each unit and perform various data processing. The processor 21 may also include an internal memory. The processor 21 executes programs stored in the memory 22 or the like to perform various processes.

[0038] The memory 22 includes various types of memory. For example, the memory 22 includes memories such as ROM, RAM, and NVM. The ROM is a non-volatile memory that cannot be rewritten. The ROM stores programs and the like to be executed by the processor 21. The RAM is a volatile memory that temporarily stores data. The RAM operates as a working memory or buffer memory. The NVM is a rewritable non-volatile memory. The NVM saves information such as control information, setting information, and processing results. The NVM of the memory 22 stores various programs for the processor 21 to execute each process described below.

[0039] The wireless tag communication unit 23 is a communicator that constitutes an RFID interface that communicates with the RFID tag 3. The wireless tag communication unit 23 is a communicator that has a communication control circuit and an antenna. However, the wireless tag communication unit 23 may also be configured as a connection interface that connects to an external antenna.

[0040] In the wireless tag communication unit 23, the communication control circuit includes a control circuit for communicating with the RFID tag 3 via the antenna. The communication control circuit causes the antenna to emit a transmission signal (radio wave) supplied from the processor 21 at a set output value. The antenna outputs the transmission signal supplied from the communication control circuit as a radio wave that can be received by the RFID tag 3. The wireless tag communication unit 23 sets a range (read area) within which the RFID tag 3 can respond based on the orientation of the antenna and the output value of the radio wave output from the antenna.

[0041] Furthermore, in the RFID tag communication unit 23, the communication control circuit not only outputs a transmission signal to the antenna but also supplies a signal received by the antenna as received data to the processor 21. The communication control circuit receives a response signal from the RFID tag 3 via the antenna, processes the response signal (received signal) received by the antenna, and supplies the signal to the processor 21. For example, the communication control circuit supplies the processor 21 with tag information included in the received signal from the RFID tag 3, an RSSI value indicating the strength of the received signal, and a phase value.

[0042] The interface 27 may be any interface that corresponds to the interface 33 included in the information terminal device 13. For example, the interface 27 may be a USB (Universal Serial Bus) interface, a LAN interface, or the like that is connected by physical contact with an interface included in the information terminal device 13. The interface 27 may also be a wireless interface that is connected for communication, such as a Bluetooth (registered trademark) interface or a Wifi (registered trademark) interface.

[0043] The reader device 10 as the radio tag communication device 1 has a power supply that supplies power for operation. In the handheld radio tag communication device 1, for example, a rechargeable battery (secondary battery) is provided as the power supply. The battery supplies power to each part of the radio tag communication device 1 to operate each part.

[0044] In the configuration example shown in Fig. 3, the information terminal device 13 is set in a holder 12 of a reader device 10 serving as the RFID tag communication device 1. The information terminal device 13 may be any device that includes a display device 14, an input device 15, etc., and that is communicatively connected to the reader device 10 serving as the RFID tag communication device 1. The information terminal device 13 is, for example, a portable information processing device such as a smartphone or a tablet PC. As shown in Fig. 3, the information terminal device 13 includes a processor 31, a memory 32, an interface (I / F) 33, a sensor 34, a camera 35, the display device 14, the input device 15, etc.

[0045] The processor 31 controls each unit, processes data, etc. The processor 31 is, for example, a CPU. The processor 31 executes programs stored in the memory 32 to realize various operations.

[0046] The interface 33 is an interface (second communication interface) for communication connection with the interface 27. The interface 33 may be any interface that is compatible with the interface 27. For example, the interface 33 is an interface such as a LAN, a USB, Bluetooth (registered trademark), or Wifi.

[0047] The sensor (sensor group) 34 includes a sensor that detects the movement of the information terminal device 13. For example, the sensor 34 is an acceleration sensor, a gyro sensor, or a geomagnetic (azimuth) sensor. The sensor 34 may also include a plurality of types of sensors. The sensor 34 may also include a position detection sensor for detecting a position. In this case, the sensor 34 is an example of a position detection sensor. Note that some or all of the sensors as the sensor 34 described above may be provided in the reader device 10.

[0048] The camera 35, for example, captures an image of the surroundings of the wireless tag communication device 1. The image capturing direction of the camera 35 changes depending on the orientation of the reader device 10 when the information terminal device 13 is set in the reader device 10. For example, the image capturing direction of the camera 35 may be set to match the orientation of the antenna of the wireless tag communication unit 23 provided in the reader device 10.

[0049] The image generated by the camera 35 is used to estimate the position (position of the device itself) of the information terminal device 13 (the RFID tag communication device 1 consisting of the reader device 10 in which the information terminal device 13 is set). The camera 35 is an example of a position detection sensor. For example, the processor 31 of the information terminal device 13 estimates (measures) its own position (position of the device itself) based on the image captured by the camera 35 using a self-position estimation method used in AR (augmented reality) technology. Note that the estimation of the self-position is not limited to using the output from the position detection sensor, and may be estimated by other methods using output from other devices.

[0050] Next, the configuration of the RFID tag communication unit 23 in the RFID tag communication device 1 according to the embodiment will be described in detail.

[0051] As described above, the RFID tag communication unit 23 has a communication control circuit and an antenna. The communication control circuit of the RFID tag communication unit 23 has a modulation circuit, a transmitting amplifier circuit, a coupler, a receiving amplifier circuit, a demodulation circuit, an output setting circuit, a level detection circuit, etc. The antenna of the RFID tag communication unit 23 is connected to the coupler in the communication control circuit. The antenna transmits and receives radio waves for communication with the RFID tag 3. The communication control circuit processes signals to be transmitted to the RFID tag 3 and signals received from the RFID tag 3 via the antenna.

[0052] The modulation circuit modulates a waveform signal (carrier wave) with the input transmission data. The amplifier circuit on the transmitting side amplifies the output signal of the modulation circuit. The coupler supplies the output signal of the amplifier circuit on the transmitting side to the antenna. With this configuration, the communication control circuit outputs a carrier wave modulated with the transmission data from the antenna.

[0053] The RFID tag 3 receives radio waves as a transmission signal transmitted from the antenna. The RFID tag 3 recognizes, for example, a read command included in the transmission signal transmitted from the antenna. When the RFID tag 3 recognizes the read command, it outputs data (tag information) stored in its own memory via radio waves, for example, by backscatter modulation.

[0054] The antenna receives radio waves as a reception signal output by the RFID tag 3. The communication control circuit acquires the reception signal received by the antenna using a coupler and supplies the acquired reception signal to a receiving amplifier circuit. The receiving amplifier circuit amplifies the reception signal received by the antenna. The demodulation circuit demodulates the data (tag information) contained in the reception signal amplified by the receiving amplifier circuit.

[0055] The antenna of the RFID tag communication unit 23 has directionality and is installed at a predetermined position of the RFID tag communication device 1 facing a predetermined direction. The antenna is, for example, a planar antenna. However, the antenna of the RFID tag communication unit 23 is not limited to a specific configuration. The antenna is placed on the housing so that it transmits electromagnetic waves (output signals) toward a communication area (reading area) centered on the direction where the directivity is maximized (for example, direction a shown in Figure 1). The RFID tag communication device 1 is configured so that the direction where the antenna's directivity is maximized is the front (direction a shown in Figure 1).

[0056] Furthermore, the communication control circuit of the RFID tag communication unit 23 sets the strength (output value) of the signal to be output by the output setting circuit. The amplifier circuit on the transmitting side amplifies the signal supplied from the modulation circuit so that it becomes the output value set by the output setting circuit. The antenna emits an output signal (radio wave) of the output value set by the output setting circuit, which is supplied from the amplifier circuit on the transmitting side via a coupler.

[0057] The wireless tag communication unit 23 sets a range (reading area) in which the RFID tag 3 can transmit radio waves to which it can respond, according to the orientation of the antenna and the output value of the radio waves output from the antenna. The reading area by the wireless tag communication unit 23 is set by the orientation of the antenna, the directivity of the antenna, and the output value of the output signal. The wireless tag communication unit 23 sets the reading area by controlling the output value of the output signal in accordance with instructions from the processor 21.

[0058] The communication control circuit of the RFID tag communication unit 23 processes the response signal (received signal) received by the antenna and supplies it to the processor 21. The communication control circuit supplies the processor 21 with tag information, an RSSI value indicating the strength of the received signal, and a phase value, which are included in the received signal from the RFID tag 3. For example, the communication control circuit of the RFID tag communication unit 23 detects information for identifying the RSSI value indicating the strength of the received signal (response signal from the RFID tag 3) received by the antenna using a level detection circuit. The processor 21 also acquires phase values ​​of multiple received signals received by the communication control circuit of the RFID tag communication unit 23 at different positions of the device itself, and detects the phase difference between the received signals received at the different positions.

[0059] The following describes a process (hereinafter referred to as tag position estimation process) for improving the accuracy of the direction in which an RFID tag 3 (wireless tag) exists and for estimating (identifying) the position of the RFID tag 3. The tag position estimation process is executed by the processor 21 in the wireless tag communication device 1, the processor in the host device 19, the processor 21 in the reader device 10, or the processor 31 in the information terminal device 13. The processors that execute the tag position estimation process may be referred to as an identification unit or an estimation unit. Note that, hereinafter, the processor 21 in the wireless tag communication device 1, the processor in the host device 19, the processor 21 in the reader device 10, and the processor 31 in the information terminal device 13 will be collectively referred to as the "processor 21."

[0060] First, a method for calculating the direction in which the RFID tag 3 exists will be described. FIG. 4 is a diagram for explaining the calculation of the direction in which the RFID tag 3 exists. FIG. 4 shows the movement of the RFID tag communication device 1 from point A to point B. In FIG. 4, point O indicates the position of the RFID tag 3 to be searched for (the position of the search object). Point A indicates the position of the RFID tag communication device 1. Point B indicates the position of the RFID tag communication device 1 after it has been moved from point A. Point B' indicates a position on the line connecting two points OA that is a distance from point O equal to the distance between two points OB, i.e., a position where OB=OB'. Angle θ forms an angle ∠OAB. Angle φ forms an angle ∠OBA.

[0061] As shown in Figure 4, let Lr be the distance between two points AB, L be the distance between two points OA, and Li be the distance between two points AB', i.e., the distance closer to the search object. Also, as shown in Figure 4, let P be the point where the perpendicular line dropped from point B to side OA intersects with side OA (the foot of the perpendicular line dropped from point B to side OA). In right-angled triangle OPB, the length of side OB is equal to the length of side OB' and is expressed as L-Li. Also, the length of side OP is expressed as L-Lr·cosθ. Also, the length of side PB is expressed as Lr·sinθ. In this case, according to the Pythagorean theorem for right-angled triangle OPB, the relationship between the distance L between OA and the angle θ is expressed by the following equation (1).

[0062] cosθ=(Lr 2 +2 L Li-Li 2 ) / 2L·Lr L=(Lr 2 -Li 2 ) / (2(Lr cosθ-Li)) (1)

[0063] Furthermore, when the wireless tag communication device 1 moves from point B to point A, that is, when it moves away from the search object, equation (2) can be derived by changing Li in equation (1) to "-Li." Note that equations (1) and (2) are examples of relational equations that represent the positional relationship between the positions of points A and B and the position of the search object (point O).

[0064] cosφ=(Lr 2 -2 L Li-Li 2 ) / 2L·Lr L=(Lr 2 -Li 2 ) / (2(Lr cosφ+Li)) (2)

[0065] In the above formulas (1) and (2), the distances Lr and Li are actually measured values. The distance Li is calculated by the processor 21 using the phase difference between the signals received from the RFID tag 3 at points A and B. The distance Lr is calculated by the processor 21 using the self-position (coordinates) at point A and the self-position (coordinates) at point B.

[0066] Furthermore, if the wireless tag communication device 1 moves from point B to point C and the angle OBC at that time is defined as angle θ', the relationship between the distance L' between O and B and the angle θ' can be expressed in the same way as in equation (1) above.

[0067] In the above formulas (1) and (2), the location of the search object is determined by L. Specifically, processor 21 calculates angle θ (or angle φ) by substituting L, Li, and Lr into formula (1). This calculation determines the angles at both ends of length Lr of side AB in triangle OAB formed by the position of the search object (point O) and points A and B. Processor 21 calculates (specifies) the position (coordinates) O of the search object by geometric calculation using length Lr of side AB and the angles at both ends of Lr.

[0068] Incidentally, the position of the search object identified by the above formula varies greatly depending on the value substituted for L. Therefore, to accurately identify the position of the search object, an appropriate value must be substituted for L, but finding an appropriate value for L, that is, identifying the position of the search object, is not easy.

[0069] Therefore, in the processor 21 of this embodiment, the position of the search object is identified based on the geometric characteristics of the position of the search object obtained by substituting a plurality of predetermined values ​​into L. Hereinafter, a method for identifying the position of the search object performed by the processor 21 of this embodiment will be described with reference to Figs. 5 to 7.

[0070] 5 to 7 are diagrams for explaining the calculation of the position where an RFID tag is located. In FIGS. 5 to 7, the space represented by the vertical and horizontal axes represents a global coordinate system in which the search object exists. The vertical axis represents the coordinate in the Y-axis direction shown in FIG. 4. The horizontal axis represents the coordinate in the X-axis direction shown in FIG. 4. In FIG. 5, the position where the search for the search object starts (for example, point A in FIG. 4) is set as the origin (0, 0). The coordinates of point O shown in FIG. 5 represent the actual position of the search object.

[0071] As described above, Lr and Li are measured as the object moves from point A to point B shown in Fig. 4. Here, by substituting a plurality of different predetermined values ​​(hereinafter also referred to as parameter values) into L, coordinates (hereinafter also referred to as calculated coordinates) specified by the pair of L and θ can be derived for each parameter value. Here, the calculated coordinates are an example of a corresponding position, and correspond to the position of the search object derived by the substituted parameter values.

[0072] 5, the calculated coordinate positions derived for each of the 10 parameter values ​​(L1 to L10) are represented by points LP1 to LP10. Here, the parameter values ​​L1 to L10 are preferably arranged in ascending or descending order. Note that if the parameter values ​​are too small, the accuracy of deriving the angle θ decreases, so it is preferable to limit the lower limit of the parameter values, for example, to 1 m or more or 2 m or more.

[0073] As shown in Fig. 5, the calculated coordinates indicate different positions depending on the parameter values, but the positions have the geometric characteristic of moving in one direction and converging in a straight line. A straight line SL1 passing through each point of the calculated coordinates passes through the coordinates of point O. The processor 21 calculates a straight line SL1 passing through each point of the calculated coordinates. There is no particular restriction on the method for calculating a straight line from a plurality of calculated coordinates, and known techniques such as linear approximation and the least squares method can be used.

[0074] Also, suppose that the calculated coordinates derived using Lr and Li measured during movement from point B to point C shown in Figure 4 and each of the parameter values ​​L1 to L10 are the positions of points LP1 to LP10 shown in Figure 6. In this case as well, the positions indicated by the calculated coordinates move in a fixed direction and converge to a linear shape. Furthermore, a line SL2 passing through each point of the calculated coordinates passes through the coordinates of point O.

[0075] Therefore, the processor 21 of this embodiment calculates two lines, line SL1 and line SL2, from the reading results of the chronologically consecutive points A → point B → point C, and identifies the position of the search object based on the calculated two lines. Specifically, as shown in Fig. 7, the intersection position of line SL1 and line SL2 is calculated, and the coordinates corresponding to the intersection position are identified as the position of the search object. The position of the search object identified in this way corresponds to the actual position of the search object.

[0076] Then, the processor 21 displays information about the position of the identified search object on the display 14, thereby notifying the operator of the radio tag communication device 1 or the reader device 10 of the position (coordinates) of the identified target tag.

[0077] After determining the position of the search object, processor 21 may continue to determine the position of the search object using the above-mentioned position determination method (hereinafter also referred to as the first position determination method) for each continuously detected self-position, or may determine the position of the search object based on the value of L derived from the determined position of the search object and the self-position.

[0078] In the latter case, processor 21 calculates the distance L between the identified position of the search object and its own position. Furthermore, when its own position moves, processor 21 calculates the distance L' between the identified position of the search object and its current own position. Then, processor 21 newly identifies the position of the search object by using the above formula (1) or the like based on the distances L, L' and the distance Lr between the positions before and after the movement. Then, processor 21 sets the calculated distance L' as the new distance L, and uses this together with the newly identified position of the search object to sequentially identify the position of the search object at each subsequently detected own position.

[0079] This allows the processor 21 to reduce the amount of calculation required to identify the position of the search object, thereby enabling the processor 21 to efficiently identify the position of the search object.

[0080] In the above-described method, when a straight line is calculated from a plurality of calculated coordinates, other straight lines appear at line-symmetric positions due to the properties of trigonometric functions, but the processor 21 selects the straight line to be used for locating the search object (RFID tag) by the following method. Fig. 8 is a diagram for explaining the method for selecting a straight line for locating the RFID tag.

[0081] As shown in FIG. 8, when a line passing through the coordinates of the search object is found using multiple parameter values ​​as the object moves from point A to point B, lines SL1 and SL1' are derived at positions that are symmetrical with respect to the line segment connecting points A and B. Similarly, when a line passing through the location of the search object is found using multiple parameter values ​​as the object moves from point B to point C, lines SL2 and SL2' are derived at positions that are symmetrical with respect to the line segment connecting points B and C. Here, of the two lines that appear symmetrical with respect to the line, one line is redundant as it does not pass through the location of the search object. Therefore, the RFID tag communication device 1 executes the following process to select a line that includes the location of the search object.

[0082] First, processor 21 calculates tip coordinates TL1 and TL1' on one end side of lines SL1 and SL1' that exist in one of the areas divided by the line segment connecting points A, B, and C. Tip coordinates TL1 and TL1' are calculated coordinates corresponding to the tip positions of both lines derived using, for example, the same parameter values. For example, when parameter values ​​L1 to L10 are used, the calculated coordinates derived using L10 can be used as tip coordinates TL1 and TL1'.

[0083] Next, processor 21 calculates tip coordinates TL2 and TL2' on one end side of both lines SL2 and SL2' that exist in the other area of ​​the area partitioned by the line segment connecting point A, point B, and point C. The tip coordinates TL2 and TL2' are calculated coordinates corresponding to the tip positions of both lines derived using the same parameter values ​​as the tip coordinates TL1 and TL1'.

[0084] Next, processor 21 calculates the distance d between the tip coordinate TL1 and the tip coordinate TL2 for straight lines SL1 and SL2. Processor 21 also calculates the distance d' between the tip coordinate TL1' and the tip coordinate TL2' for straight lines SL1' and SL2'.

[0085] Then, processor 21 compares distance d with distance d' and specifies the position of the search object using the two lines with the shorter distance. For example, in the case of Fig. 7, since distance d is shorter, processor 21 specifies the position of the search object by calculating the coordinates of the intersection of the two lines, line SL1 and line SL2.

[0086] As a result, the RFID tag communication device 1 can specify the location of the search object using two straight lines that pass through the position of the search object, and therefore can efficiently specify the location of the search object.

[0087] In the above example, the position of the search object is identified based on the reading results of three consecutive points (point A → point B → point C), but this is not limiting, and discontinuous points may be included along the way. For example, if the self-position moves in the order of point A → point B → point C → point D, processor 21 may calculate one straight line relating to the position identification of the search object from the reading results of the two points A → point B, and may calculate the other straight line relating to the position identification of the search object from the reading results of the two points C → point D that are separated in time series from the detection timing of the positions of the two points.

[0088] In the above example, two straight lines related to the position identification of the search object are derived and the position of the search object is identified by finding the intersection of the two straight lines, but the number of straight lines derived for identifying the position of the search object is not limited to two. For example, processor 21 may derive three or more straight lines related to the position identification of the search object and identify the position of the search object based on the intersection of these straight lines. In this case, for example, processor 21 may identify the coordinates of an area surrounded by three or more straight lines as the position of the search object.

[0089] Furthermore, the timing for acquiring the read result is not particularly limited and can be set arbitrarily. For example, the processor 21 may acquire the read result every time the wireless tag communication unit 23 transmits radio waves n times (n is an integer equal to or greater than 1). Furthermore, for example, the processor 21 may acquire the read result every time the moving distance of its own position reaches a predetermined value.

[0090] The configuration of this embodiment has been described above. An example of the operation of the RFID tag communication device 1 or the reader device 10 will now be described.

[0091] First, a procedure of a process for estimating the position of a wireless tag (hereinafter referred to as a first tag position estimation process) executed by the wireless tag communication device 1 or the reader device 10 will be described with reference to Fig. 9. Fig. 9 is a flowchart showing an example of the procedure of the first tag position estimation process.

[0092] (Step S11) The search object to be searched for is specified by an operator's instruction via the input device 15. The search object is not limited to being specified by product name, and any item related to tag information can be specified as appropriate. The processor 21 identifies the RFID tag 3 to be searched for that corresponds to the specified search object. Identification of the RFID tag 3 to be searched for (hereinafter referred to as the target tag) is, for example, identification of the ID of the search object that corresponds to the specified search object.

[0093] (Step S12) Processor 21 starts estimating its own position (the position of the device itself) in response to an instruction from an operator to start a search. For example, processor 21 estimates its own position (the position of the device itself) by a self-position estimation method used in AR (augmented reality) technology based on an image captured by camera 26 or 35. Processor 21 may also acquire information indicating the self-position estimated by processor 31 of information terminal device 13 from an image captured by camera 35. Processor 21 may also identify the position of the device itself from information other than the image captured by the camera.

[0094] (Step S13) The processor 21 starts the reading process of the target tag in response to an instruction from the operator to start a search. The processor 21 outputs a response request (read command) as an output signal of a predetermined output value from the wireless tag communication unit 23. The wireless tag communication unit 23 communicates with the wireless tag. Specifically, the wireless tag communication unit 23 receives a reception (response) signal as a response wave output by an RFID tag in the reading area. When the wireless tag communication unit 23 receives a signal from the RFID tag, it extracts tag information indicated by the reception signal and supplies the extracted tag information to the processor 21.

[0095] (Step S14) The processor 21 determines whether or not the target tag has been read based on the tag information included in the signal received by the wireless tag communication unit 23. The processor 21 identifies the identification information included in the tag information of the received signal received by the wireless tag communication unit 23. The processor 21 determines whether or not the target tag has been read based on whether or not the identification information included in the received signal matches the identification information of the target tag. If the target tag has not been read (No in step S14), the processor 21 performs the process of step S14 again to read the RFID tag 3. If the target tag has been read (Yes in step S14), the process of step S15 is executed.

[0096] (Step S15) When the processor 21 reads a target tag, it stores (records) the read result of the target tag in the memory 22. For example, the processor 21 stores read information such as the position, orientation (read direction), output value, and phase value as the read result of the target tag in the memory 22. The position is information indicating the self-position when the RFID tag is read.

[0097] The orientation (reading direction) is information indicating the orientation of the antenna (the orientation of the wireless tag communication device 1 or the orientation of the reader device 10) when the RFID tag 3 is read. The processor 21 acquires information indicating the orientation of the antenna detected by the sensor 24 or 34. The processor 21 may also detect the orientation of the antenna based on an image captured by the camera 26 or 35.

[0098] The output value is the strength of the output signal (radio wave) output from the antenna when reading the RFID tag 3. The output value is set by the output setting circuit of the communication control circuit in accordance with an instruction from the processor 21.

[0099] The phase value is the phase of the radio wave received by the antenna from the target tag as a signal. The phase value is detected from the signal received by the target tag by a phase detection circuit included in the communication control circuit. The processor 21 acquires the phase value detected by the phase detection circuit.

[0100] (Step S16) Next, processor 21 determines whether the target tag has been read at a position different from that of step S14. For example, processor 21 determines whether the target tag has been read at a position different from that included in the read result stored in memory 22. If the target tag has not been read (No in step S16), processor 21 performs the process of step S16 again to read the RFID tag 3. If the target tag has been read (Yes in step S16), the process of step S17 is executed.

[0101] (Step S17) When the processor 21 reads the target tag, it stores (records) the reading result of the target tag in the memory 22. In step S17, similar to step S15, the memory 22 holds reading information such as the position, orientation (reading direction), output value, and phase value.

[0102] (Step S18) Based on the read results stored in the memory 22 in steps S15 and S17, the processor 21 derives a relational expression that expresses the positional relationship between each position (read position) included in the read results and the position of the target tag. Specifically, the processor 21 uses the coordinates of each position included in the read results to calculate the distance Lr between the positions. The processor 21 also calculates the distance Li by which the RFID tag communication device 1 approaches the target tag based on the difference in phase value at each position included in the read results. The processor 21 then substitutes the calculated distance Lr and distance Li into the above-mentioned formula (1) (or formula (2)) to derive a relational expression that expresses the positional relationship between each read position and the position of the target tag.

[0103] (Step S19) Processor 21 calculates calculated coordinates for each parameter value by substituting multiple parameter values ​​for L included in the relational expression derived in step S18. For example, when ten parameter values ​​(L1 to L10) are used, processor 21 calculates calculated coordinates for each of L1 to L10. Note that the relational expression used to calculate the calculated coordinates can be differentiated depending on the positive or negative sign of distance Li. For example, when distance Li is a positive value, processor 21 calculates calculated coordinates using equation (1). Furthermore, when distance Li is a negative value, processor 21 calculates calculated coordinates using equation (2).

[0104] (Step S20) Based on each of the calculated coordinates derived in step S19, the processor 21 calculates a straight line passing through the calculated coordinates. For example, the processor 21 calculates the straight line from the plurality of calculated coordinates by using a known technique such as linear approximation or the least squares method.

[0105] (Step S21) Next, the processor 21 determines whether the target tag has been read at a position different from that in steps S14 and S16. For example, the processor 21 determines whether the target tag has been read at a reading position different from the reading position included in the reading result stored in the memory 22. If the target tag has not been read (No in step S21), the processor 21 performs the process of step S21 again to read the RFID tag 3. If the target tag has been read (Yes in step S21), the processor 21 executes the process of step S22.

[0106] (Step S22) When the processor 21 reads the target tag, it stores (records) the reading result of the target tag in the memory 22. In step S22, similar to steps S15 and S17, the memory 22 stores reading information such as the position, orientation (reading direction), output value, and phase value.

[0107] (Step S23) Based on the read results stored in the memory 22 in steps S17 and S22, the processor 21 derives a relational expression that represents the positional relationship between each read position included in the read results and the target tag.

[0108] (Step S24) Processor 21 calculates calculated coordinates for each parameter value by substituting a plurality of parameter values ​​into L included in the relational expression derived in step S23.

[0109] (Step S25) Based on each of the calculated coordinates derived in step S24, the processor 21 calculates a straight line that passes through the calculated coordinates.

[0110] (Step S26) Processor 21 calculates the coordinates of the intersection of two lines, the line derived in step S20 and the line derived in step S25. For example, processor 21 calculates the coordinates of the intersection of both lines by solving simultaneous equations of linear functions that represent each line. Processor 21 selects the pair of lines to be used in calculating the coordinates of the intersection using the selection method described above.

[0111] (Step S27) Processor 21 identifies (estimates) the intersection coordinates calculated in step S26 as the position of the target tag.

[0112] (Step S28) The processor 21 notifies the operator of the position of the identified target tag. For example, the processor 21 controls the display 14 so as to notify the operator of the position of the identified target tag. As a result, the display 14 displays the position (coordinates) of the RFID tag 3 that has been identified as the target tag. Note that the notification of the position (coordinates) of the RFID tag 3 to the operator is not limited to displaying it on the display 14. For example, the processor 21 may notify the operator of the position (coordinates) of the RFID tag 3 via an audio device.

[0113] Next, the procedure of the process of estimating the position of the RFID tag 3 (hereinafter referred to as the second tag position estimation process) executed by the wireless tag communication device 1 or the reader device 10 will be described with reference to Fig. 10. Fig. 10 is a flowchart showing an example of the procedure of the second tag position estimation process. Note that this process is executed following the first tag position estimation process described in Fig. 9.

[0114] (Step S31) The processor 21 identifies the position of the target tag. Specifically, the processor 21 identifies the position of the target tag by the first tag position estimation process described above, and stores the identified position of the target tag in the memory 22 or the like.

[0115] (Step S32) The processor 21 determines whether or not the target tag has been read based on the tag information included in the signal received by the wireless tag communication unit 23. If the target tag has not been read (No in step S32), the processor 21 performs the process of step S32 again to read the RFID tag 3. If the target tag has been read (Yes in step S32), the processor 21 performs the process of step S33.

[0116] (Step S33) The processor 21 calculates the value of L based on the position of the target tag and its own position. Specifically, the processor 21 calculates L, which indicates the distance between the position of the target tag and its current own position. The processor 21 stores the calculated value of L in the memory 22 or the like.

[0117] (Step S34) When the processor 21 reads the target tag, it stores (records) the reading result of the target tag in the memory 22. For example, the processor 21 stores reading information such as the position, orientation (reading direction), output value, and phase value in the memory 22 as the reading result of the target tag.

[0118] (Step S35) Next, processor 21 determines whether the target tag has been read at a position different from that of step S14. For example, processor 21 determines whether the target tag has been read at a position different from that included in the read result stored in memory 22. If the target tag has not been read (No in step S35), processor 21 performs the process of step S35 again to read the RFID tag 3. If the target tag has been read (Yes in step S35), the process of step S36 is executed.

[0119] (Step S36) When the processor 21 reads the target tag, it calculates L' based on the position of the target tag and its own position. Specifically, the processor 21 calculates L' indicating the distance between the position of the target tag and its current own position. The processor 21 stores (records) the calculated value of L' in the memory 22 or the like.

[0120] (Step S37) The processor 21 stores (records) the reading result of the target tag read in step S35 in the memory 22. In step S37, similar to step S34, the memory 22 holds reading information such as the position, orientation (reading direction), output value, and phase value.

[0121] (Step S38) Processor 21 identifies the position of the target tag based on L and L' stored in memory 22 and the read result of the target tag. For example, processor 21 calculates, from the read result stored in memory 22, the distance Lr from the first position where the target tag was read in step S32 to the second position where the target tag was read in step S35. Furthermore, L and L stored in memory 22 correspond to the distance from the first position to the target tag, and L' corresponds to the distance from the second position to the target tag. As a result, the lengths of the sides of triangle OAB shown in FIG. 4 are the same, so processor 21 can identify the position of the target tag by using the above formula (1) etc.

[0122] (Step S39) Processor 21 updates the position of the target tag held in step S31 to the position of the target tag identified in step S38. For example, processor 21 corrects the position of the target tag held in memory 22 to the position of the target tag identified in step S38, or overwrites it with the position of the target tag identified in step S38.

[0123] (Step S40) The processor 21 notifies the operator of the position (coordinates) of the target tag identified in step S38. For example, the processor 21 controls the display 14 to notify the operator of the position of the identified target tag. As a result, the display 14 displays the position (coordinates) of the RFID tag 3 that has been identified as the target tag.

[0124] (Step S41) The processor 21 determines whether the operator has found the target tag. For example, the processor 21 determines that the operator has found the target tag when the operator gives an instruction via the input device 15 that the target tag has been found. Furthermore, for example, the processor 21 determines that the operator has found the target tag when the distance between the target tag and its own position falls below a threshold (for example, 1 m).

[0125] If the operator determines that the target tag has not been found (No in step S41), processor 21 continues searching for the target tag by re-executing the process of step S32. If the operator determines that the target tag has been found (Yes in step S41), processor 21 ends this process.

[0126] As described above, the RFID tag communication device 1 or the reader device 10 according to this embodiment includes the RFID tag communication unit 23 that communicates with the RFID tag 3, the position detection sensor that detects the position of the RFID tag communication unit 23, the memory 22 that stores a read result that associates the position detected by the position detection sensor with the phase of the radio wave received from the RFID tag 3 by the RFID tag communication unit 23 at that position, and the processor 21 that identifies the position of the RFID tag 3 based on the read results at multiple positions stored in the memory 22. The processor 21 also derives a relational expression that represents the positional relationship between each of the two consecutive positions and the position of the RFID tag 3 based on the read results at two consecutive positions, and calculates multiple corresponding positions corresponding to the position of the RFID tag 3 by substituting multiple parameter values ​​that represent the distance to the RFID tag 3 into the relational expression, calculates a straight line that passes through the corresponding positions based on the calculated multiple corresponding positions, and identifies the position of the intersection of the straight line derived based on the positions of the pair of two points and the straight line derived based on the positions of the other pair of two points as the position of the RFID tag 3.

[0127] As a result, the radio tag communication device 1 or reader device 10 according to the present embodiment can identify the position of the RFID tag 3 based on the read results at at least three positions. Therefore, the radio tag communication device 1 or reader device 10 according to the embodiment can efficiently and accurately estimate the position of the RFID tag 3. From the above, the radio tag communication device 1 or reader device 10 according to the present embodiment can efficiently search for the target tag.

[0128] Furthermore, the RFID tag communication device 1 or the reader device 10 according to the embodiment can display information about the position of the identified RFID tag 3 on the display 14. As a result, the RFID tag communication device 1 or the reader device 10 according to the embodiment can improve the efficiency of searching for the target tag.

[0129] When the technical idea of ​​the embodiment is realized by a program, the program causes a computer to communicate with the RFID tag 3 via the wireless tag communication unit 23, detect the position of the wireless tag communication unit 23, store in memory 22 a read result that associates the detected position with the phase of the radio waves received from the RFID tag 3 at that position, and identify the position of the RFID tag 3 based on the read results at multiple positions stored in memory 22.The program causes the computer to execute (realize) the following: derive a relational equation that represents the positional relationship between each of the two consecutive positions and the position of the RFID tag 3 based on the read results at the two consecutive positions; calculate multiple corresponding positions corresponding to the position of the RFID tag by substituting multiple parameter values ​​that represent the distance to the RFID tag 3 into the relational equation; calculate a straight line that passes through the corresponding positions based on the calculated multiple corresponding positions; and identify the intersection position of the straight line derived based on the positions of two pairs of points and the straight line derived based on the positions of another pair of two points as the position of the RFID tag 3.

[0130] For example, the tag position estimation process (first tag position estimation process, second tag position estimation process) can be realized by installing the program in a computer such as the RFID tag communication device 1 shown in FIG. 1, the higher-level device 19 on the network, or the reader device 10 shown in FIG. 3, and expanding the program in memory. In this case, the program that can cause a computer to execute the tag position estimation process can also be stored and distributed in a storage medium such as a magnetic disk (hard disk, etc.), an optical disk (CD-ROM, DVD, etc.), or a semiconductor memory. Furthermore, the distribution of the program is not limited to the above-mentioned media, and may be distributed using an electric communication function, such as downloading via the Internet. The processing procedure of the program conforms to the tag position estimation process of the embodiment. Furthermore, the effects of the program are the same as those of the embodiment. For these reasons, a description of the processing procedure and effects of the program will be omitted.

[0131] Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the scope of the invention and its equivalents as defined in the claims. [Explanation of symbols]

[0132] 1. Radio tag communication device 3. Wireless tags 10 Reader device 11 Gripping part 12 Holding part 13 Information terminal equipment 14 Display 15 Input Device 21 processors 22 Memory 23 Wireless tag communication unit (communication device) 24 Sensor (position detection sensor) 25 Communication Interface 26 Camera (position detection sensor) 27 Interface 31 processors 32 memory 33 Interface 34 Sensor (position detection sensor) 35 Camera (position detection sensor) [Prior art documents] [Patent documents]

[0133] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-237941

Claims

1. a communicator for communicating with the wireless tag; a position detection sensor that detects the position of the communication device; a storage unit that stores a read result that associates the position detected by the position detection sensor with the phase of the radio wave received from the wireless tag by the communication device at the position; a processor that identifies the position of the wireless tag based on the read results at the multiple positions stored in the storage unit; Equipped with The processor: deriving a relational expression representing a positional relationship between each of the two consecutive positions and the position of the wireless tag based on the reading results at the two consecutive positions; calculating a plurality of corresponding positions corresponding to the position of the wireless tag by substituting a plurality of parameter values ​​representing distances to the wireless tag into the relational expression; calculating a straight line passing through the corresponding positions based on the plurality of corresponding positions; Identifying the position of the intersection of the line derived based on the positions of the two points forming a pair and the line derived based on the positions of the other two points forming a pair as the position of the wireless tag; Radio tag communication device.

2. The processor: Identifying the position of the wireless tag based on the straight line derived based on the positions of the first two points and the straight line derived based on the positions of the latter two points among the positions of the three consecutive points; The radio tag communication device according to claim 1 .

3. The processor: identifying the position of the wireless tag based on the straight line derived based on two consecutive positions among the plurality of positions detected by the position detection sensor and the straight line derived based on two other consecutive positions that are separated in time series from the detection timing of the two consecutive positions detected by the position detection sensor; The radio tag communication device according to claim 1 .

4. The processor: For each pair of the two points, two straight lines are calculated that are symmetrical with respect to a line segment connecting the two points; For each area divided by the line segments, a distance between tip positions of two of the straight lines existing in the same area is calculated; Identifying the position of the wireless tag based on the two straight lines that exist in the area where the calculated distance between the tip positions is shorter. The radio tag communication device according to any one of claims 1 to 3.

5. The processor: displaying information about the identified location of the wireless tag on a display; The radio tag communication device according to claim 1 .

6. On the computer, Communicate with the wireless tag via the communication device, Detecting the location of the communicator; storing the read result in a memory unit, the read result correlating the detected position with the phase of the radio wave received from the wireless tag at the position; a program for executing a process of identifying a position of the wireless tag based on the read results at a plurality of positions stored in the storage unit, The program causes the computer to: deriving a relational expression representing a positional relationship between each of the two consecutive positions and the position of the wireless tag based on the reading results at the two consecutive positions; calculating a plurality of corresponding positions corresponding to the position of the wireless tag by substituting a plurality of parameter values ​​representing distances to the wireless tag into the relational expression; calculating a straight line passing through the corresponding positions based on the plurality of corresponding positions; Identifying the position of the intersection of the line derived based on the positions of two pairs of points and the line derived based on the positions of another pair of points as the position of the wireless tag; A program that makes it happen.

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