Radio tag communication device and program

Abstract

To increase precision of a direction in which a radio tag is present and locate the position of the radio tag.SOLUTION: A radio tag communication device comprises: a communication device; a position detection sensor; and a processor. The communication device communicates with a radio tag. The position detection sensor detects the position of the communication device. The processor locates the middle point of two positions in which the phase matches as a first position from among the phases obtained when the communication device travels on an arc. The processor locates a position different from the first position as a second position in a movement path on the arc. The processor calculates a central angle of a sector formed by the first position, the second position, and the arc. The processor locates the position of the radio tag by using the central angle, the first position, and the second position.SELECTED DRAWING: Figure 8

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 are radio frequency tag communication devices that aim to find RFID tags (hereinafter also referred to as wireless tags) in unspecified locations. Radio frequency tag communication devices communicate with RFID tags by changing the position and orientation of the antenna through operation by an operator. Conventional radio frequency tag communication devices estimate the direction of the RFID tag to be searched for based on the communication status with the RFID tag to be searched for.

[0003] Conventional RFID tag communication devices notify an operator of the direction in which an RFID tag is located by displaying a guidance screen on a display that includes an estimation result of the direction in which an RFID tag is located. The operator searches for the RFID tag or an item with an RFID tag attached while moving in the direction displayed on the display. Conventionally, if distance information between the RFID tag communication device and the RFID tag cannot be obtained, the accuracy of calculating the direction in which the RFID tag is located is insufficient. In addition, conventional estimation results have the problem of not being able to estimate the position of the RFID tag. 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 improve the accuracy of the direction in which a radio tag is present and identify the position of the radio tag. [Means for solving the problem]

[0005] An embodiment of a wireless tag communication device includes a communicator, a position detection sensor, and a processor. The communicator communicates with a wireless tag. The position detection sensor detects the position of the communicator. The processor identifies the position of the wireless tag based on the phase of radio waves collected through communication between the wireless tag and the communicator. The processor identifies, as a first position, the midpoint of two positions where the phases match, among the phases obtained when the communicator moves on an arc. The processor identifies, as the second position, a position on the movement path on the arc that is different from the first position. The processor calculates a central angle of a sector formed by the first position, the second position, and the arc. The processor identifies the position of the wireless tag using the central angle, the first position, and the second position. [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 direction in which the RFID tag exists according to the embodiment. [Figure 6] FIG. 6 is a diagram illustrating an example of geometry related to determining the distance between a wireless tag and a first position according to the embodiment. [Figure 7] FIG. 7 is a diagram showing an example of geometry relating to specifying the position (coordinates) of a wireless tag using the first position and the origin set in FIG. 6 according to the embodiment. [Figure 8]FIG. 8 is a flowchart illustrating an example of a procedure for tag position estimation processing according to the embodiment. [Figure 9] FIG. 9 is a flowchart illustrating an example of a procedure for tag position estimation processing in an application example of the embodiment. [Figure 10] FIG. 10 is a flowchart illustrating an example of a procedure for tag position estimation processing in an application example of 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 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 according to an operation by an operator. For example, the radio-frequency tag communication device 1 is operated as a search device for searching for items with RFID tags 3 attached within a predetermined area (search range) such as a warehouse or a store. The radio-frequency tag communication device 1 as a search device continuously reads the RFID tags 3 to be searched while changing its position according to an operation by an operator.

[0013] The radio tag communication device 1 receives a response signal from the RFID tag 3 present within the 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 an 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 its own device, in the memory 22 as the reading results.

[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 holder 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 holder 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 results of the RFID tag 3 within a read area that is set by the antenna orientation 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 results 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, in the memory 22 as the read results of a specific RFID tag 3. 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 a radio 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 radio waves 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 waves 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 processed 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 (Received Signal Strength Indicator) value indicating the strength of the received signal, and a phase value.

[0029] The sensor (sensor group) 24 detects the movement of the wireless 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 wireless 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 estimated by 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 and the like. The input unit 15 is realized by, for example, hard switches and / or buttons, a touch panel shared with the display unit 14, or the like. 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, or the like 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 the parts. 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. ROM is a non-volatile memory that cannot be rewritten. ROM stores programs executed by the processor 21. RAM is a volatile memory that temporarily stores data. RAM operates as a working memory or buffer memory. NVM is a rewritable non-volatile memory. 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 26 may be any interface that corresponds to the interface 33 included in the information terminal device 13. For example, the interface 26 may be a USB (Universal Serial Bus) interface or a LAN interface, which is connected by physical contact with an interface included in the information terminal device 13. The interface 26 may also be a wireless interface, 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 the holder 12 of the 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 26. The interface 33 may be any interface that is compatible with the interface 26. For example, the interface 33 is an interface such as a LAN, USB, Bluetooth, or Wi-Fi.

[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 be configured to include multiple 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 serving as the sensor 34 described above may be configured to 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 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, and a level detection circuit. 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 contained 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 a wireless tag (RFID tag) 3 exists and estimating (identifying) the position of the wireless 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 processor that executes the tag position estimation process may be referred to as an identification unit or an estimation unit.

[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 S 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 SA that is a distance from point S that is the distance between two points SB, i.e., a position where SB = SB'. Angle η indicates ∠SAB. Angle φ forms ∠SBA.

[0061] As shown in Figure 4, the distance between two points AB is Lr, the distance between two points SA is L, and the distance between two points AB' is Li'. Also, as shown in Figure 4, the intersection of the perpendicular line dropped from point B to side SA and side SA (the foot of the perpendicular line dropped from point B to side SA) is point P. In right triangle SPB, the length of side SB is equal to the length of side SB' and is expressed as L-Li. Also, the length of side SP is expressed as L-Lr·cosη. Also, the length of side PB is expressed as Lr·sinη. In this case, according to the Pythagorean theorem for right triangle SPB, the relationship between the distance L between SA and the angle η is expressed by the following equation (1).

[0062] cosη=(Lr 2 +2 L Li-Li 2 ) / 2LLr L=(Lr 2 -Li2 ) / (2(Lr cosη-Li)) (1)

[0063] FIG. 5 is a diagram for explaining the calculation of the direction in which the RFID tag 3 is located. FIG. 5 shows the movement of the RFID tag communication device 1 from point B to point A. As shown in FIG. 5, the intersection of a perpendicular line dropped from point A to a straight line SB and the straight line SB (the foot of the perpendicular line dropped from point A to side SB) is defined as point Q. In right-angled triangle SQA, the length of side SA is SB' + B'A, and is therefore expressed as L + Li. The length of side SQ is expressed as Lr sinφ. The length of side QB is expressed as -Lr cosφ. Therefore, the length of side SQ is L - Lr cosφ. In this case, according to Pythagoras' theorem for right-angled triangle SQA, the relationship between the distance L between SA and the angle φ is expressed by the following equation (2).

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

[0065] Since equation (2) is the movement of the RFID tag communication device 1 from point B to point A, equation (2) can be derived from equation (1) by changing Li in equation (1) to "-Li." In the above equations (1) and (2), the distances Lr and Li are actually measured values. The distance Li is calculated by the processor 21 or the like using the phase difference between the signals received from the RFID tag 3 at point A and point B. The distance Lr is calculated by the processor 21 or the like using the self-position (coordinates) at point A and the self-position (coordinates) at point B.

[0066] Conventionally, the angles η and φ corresponding to the direction in which the RFID tag 3 is present are calculated by setting the distance L to a predetermined length. Therefore, conventionally, there is a possibility that an error may occur in the direction in which the RFID tag 3 is present. On the other hand, in this embodiment, the distance L is calculated by the following method, and the calculated distance L is used to identify the direction in which the RFID tag 3 is present according to equations (1) and (2).

[0067] FIG. 6 is a diagram showing an example of geometry related to determining point A in relation to determining distance L. Hereinafter, point A will be referred to as a first position. As shown in FIG. 6, the RFID tag communication unit (communicator) 23 is moved on the arc ARC. The movement of the RFID tag communication unit (communicator) 23 on the arc ARC corresponds to, for example, an operation in which an operator holding the RFID tag communication device 1 or the reader device 10 is positioned at the origin O, the operator bends his or her elbow so that it is horizontal, and moves the RFID tag communication device 1 or the reader device 10 within a horizontal plane (hereinafter referred to as a rotation operation). At this time, the processor 21 acquires phase values ​​at each of a plurality of points on the arc ARC via the RFID tag communication unit 23. The processor 21 identifies two identical phase values ​​from among a plurality of phase values ​​corresponding to the plurality of points. Note that the rotation operation is not limited to the above and may be, for example, an operation in which the operator holding the RFID tag communication device 1 or the reader device 10 changes direction.

[0068] 6, points D and E correspond to the positions of the RFID tag communication device 1 or the reader device 10 where the same phase value is obtained. That is, points D and E correspond to two positions where the phase value is the same. At this time, the processor 21 estimates its own position (coordinates) at point D based on the output from the position detection sensor at point D. The processor 21 also estimates its own position (coordinates) at point E based on the output from the position detection sensor at point E.

[0069] Next, processor 21 identifies the coordinates of origin O using its own position at point D and its own position at point E. In addition, processor 21 identifies the coordinates of the midpoint between its own position at point D and its own position at point E. Based on these, processor 21 identifies the identified midpoint as first position A. That is, processor 21 identifies the midpoint of two positions where the phases match, among the phases obtained when communicator 23 moves on the arc ARC, as first position A. As shown in FIG. 6, first position A is located on a straight line connecting origin O and the position of wireless tag 3. Also, as shown in FIG. 6, first position A corresponds to the position on the arc ARC that is closest to the position of wireless tag 3 (position S).

[0070] FIG. 7 is a diagram showing an example of geometry related to specifying the position (coordinates) of the wireless tag 3 using the first position set in FIG. 6 and the origin O. As shown in FIG. 7, the origin O corresponds to the center point of the arc ARC. As shown in FIG. 7, the operator moves the wireless tag communication device 1 or the reader device 10 from the first position A to a second position B different from the first position A on the arc ARC having the origin O as the center and the distance between the origin O and the first position A as the radius. This movement corresponds to a rotational movement of the wireless tag communication device 1 or the reader device 10. At this time, the processor 21 estimates its own position (coordinates) at point B based on an output from the position detection sensor at point B. As a result, the processor 21 specifies a position (coordinates) different from the first position A as the second position B on the movement path of the communicator 23 on the arc ARC, as shown in FIG. 7.

[0071] 7, the first position A, the second position B, and the origin (center point) O form an isosceles triangle. Furthermore, the processor 21 calculates the central angle θ of the sector formed by the first position A, the second position B, and the arc ARC using the coordinates of the first position A, the second position B, and the origin O. The central angle θ is calculated using, for example, the distance (radius) between the origin O and the first position A, and the distance Lr between the first position A and the second position B.

[0072] 7, processor 21 calculates two base angles (∠OAB and ∠OBA)α of an isosceles triangle using central angle θ. Also, as shown in FIG. 7, processor 21 calculates the exterior angle (θ+α) of the isosceles triangle when the side including center point O is extended toward wireless tag 3 using central angle θ and base angle α.

[0073] Position A' shown in FIG. 7 indicates a position that is separated from position S of the wireless tag 3 by the distance L between the wireless tag 3 and the first position A (hereinafter referred to as the first distance) on the line connecting position S of the wireless tag 3 and second position B. As shown in FIG. 7, distance Li between point A' and point B corresponds to the difference between the first distance L and the distance from the wireless tag 3 to the second position B (hereinafter referred to as the first difference). Therefore, distance Li is calculated by the processor 21 or the like using the phase difference between the signals received from the RFID tag 3 at points A and B. Furthermore, processor 21 calculates distance Lr between the first position A and the second position B (hereinafter referred to as the second distance) using the coordinates of the first position A and the second position B.

[0074] From these, the processor 21 calculates the exterior angle (θ+α), the first difference Li, and the second distance Lr shown in Fig. 7. Then, the processor 21 calculates (identifies) the position (coordinates) S of the wireless tag 3 by performing the elementary geometric calculations described in Fig. 4 and Fig. 5. Specifically, the processor 21 calculates (identifies) the position (coordinates) S of the wireless tag 3 using the relational expressions described in Fig. 5.

[0075] 5 and 7, the symbols A and B are reversed for convenience of explanation. That is, point A in FIG. 5 corresponds to point B in FIG. 7, and point B in FIG. 5 corresponds to point A in FIG. 7. The processor 21 uses the exterior angle (θ+α) as φ shown in FIG. 5 and substitutes the exterior angle (θ+α), the first difference Li, and the second distance Lr into equation (2) to calculate the first distance L. Next, the processor 21 substitutes the first distance L, the first difference Li, and the second distance Lr into equation (1) to calculate ∠SBA(∠η). That is, the processor 21 calculates the first angle (∠SBA(∠η)) between the side connecting the first position A and the second position B and the side connecting the wireless tag 3 and the second position B using the first distance L, the second distance Lr, and the first difference Li.

[0076] By the above calculation, in the triangle △SAB formed by the position S of the wireless tag 3, the first position (point A), and the second position (point B), the angles (exterior angles (θ+α) and ∠η) at both ends of the length Lr of the side AB corresponding to the second distance are found. The processor 21 calculates (identifies) the position (coordinate) S of the wireless tag 3 by elementary geometry calculations using the length Lr of the side AB and the angles (exterior angles (θ+α) and ∠η) at both ends of Lr. From the above, the processor 21 identifies the position (coordinate) S of the wireless tag 3.

[0077] The configuration of this embodiment has been described above. Below, we will explain the procedure of the process of estimating the position of the wireless tag 3 (hereinafter referred to as tag position estimation process) executed by the wireless tag communication device 1 or the reader device 10. Figure 8 is a flowchart showing an example of the procedure of the tag position estimation process.

[0078] (Tag position estimation process) (Step S801) 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 wireless tag 3 to be searched for that corresponds to the specified search object. Identification of the wireless tag 3 to be searched for (hereinafter referred to as the target tag) may be, for example, identification of the ID of the search object that corresponds to the specified search object.

[0079] (Step S802) 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.

[0080] (Step S803) The processor 21 determines whether 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 the target tag has been read based on whether 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 S803), the processor 21 performs the process of reading the RFID tag 3 by executing the process in step S803 again. If the target tag has been read (Yes in step S803), the process of step S804 is executed.

[0081] (Step S804) The processor 21 stores (records), for example, read information as a result of reading 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 a result of reading the target tag in the memory 22. The position is information indicating the position of the device itself (the radio tag communication device 1 or the reader device 10) when the RFID tag was read.

[0082] For example, processor 21 estimates its own position (the position of its own device) 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 its own position estimated by processor 31 of information terminal device 13 from an image captured by camera 35. Processor 21 may also specify the position of its own device from information other than the image captured by the camera.

[0083] 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.

[0084] 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.

[0085] 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.

[0086] (Step S805) The processor 21 acquires data while swinging the RFID tag communication device 1 or the reader device 10 on the circular arc ARC by a rotational motion by the operator. Specifically, as shown in FIG. 6, the processor 21 identifies two points (points D and E shown in FIG. 6) on the circular arc ARC that have the same phase value. Note that the rotational motion is not limited to the above, and may be, for example, a motion of changing the orientation of the operator holding the RFID tag communication device 1 or the reader device 10. During the rotational motion, the position detection sensor detects the position of the communicator 23.

[0087] In addition, processor 21 estimates its own position (coordinates) at point D based on the output from the position detection sensor at point D. Processor 21 also estimates its own position (coordinates) at point E based on the output from the position detection sensor at point E. Using the self-position at point D and the self-position at point E, processor 21 identifies the coordinates of origin O and the coordinates of the midpoint between points D and E, as shown in FIG. 7. Based on these, processor 21 identifies the identified midpoint as a first position A.

[0088] (Step S806) 7, the processor 21 determines a second position B different from the first position A on an arc ARC having the origin O as its center and the distance between the origin O and the first position A as its radius. At this time, the processor 21 estimates (calculates) its own position (coordinates) at point B based on the output from the position detection sensor at point B.

[0089] (Step S807) Processor 21 calculates the distance Lr between first position A and second position B using the coordinates of first position A and the coordinates of second position B. Next, processor 21 calculates the central angle θ of the sector AOB shown in FIG. 7 using the distance (radius) between origin O and first position A and the calculated distance Lr.

[0090] (Step S808) The processor 21 calculates the base angles (∠OAB and ∠OBA)α of the isosceles triangle OAB shown in Fig. 7 using the central angle θ. Also, as shown in Fig. 7, the processor 21 calculates the exterior angle BAS (θ+α) of the isosceles triangle OAB using the central angle θ and the base angle α. As shown in Fig. 7, the exterior angle (θ+α) of the isosceles triangle OAB corresponds to the exterior angle (∠BAS) of the isosceles triangle OAB when the side connecting the center point O and the first position A is extended in a direction away from the center point O toward the wireless tag 3 beyond the first position A.

[0091] (Step S809) The processor 21 calculates the first distance L by substituting the exterior angle (θ+α) for φ in the equation (2) and substituting the first difference Li and the second distance Lr into the equation (2).

[0092] (Step S810) By substituting the first distance L, the first difference Li, and the second distance Lr into equation (1), the processor 21 calculates the angle between the side connecting the first position A and the second position B and the side connecting the wireless tag 3 and the second position B, that is, ∠SBA in the triangle SBA shown in Fig. 7, as the first angle. Through the above processing, the angles at both ends of the second distance Lr (exterior angles (θ+α) and ∠η) in the triangle OAB shown in Fig. 7 are determined.

[0093] (Step S811) The processor 21 calculates (identifies) the position (coordinate) S of the wireless tag 3 using the length Lr of the side AB and the angles at both ends of Lr (exterior angles (θ+α) and ∠η). The method for calculating (identifying) the position (coordinate) S of the wireless tag 3 using the length Lr of the side AB and the angles at both ends of Lr (exterior angles (θ+α) and ∠η) can be implemented by known elementary geometry calculations using Pythagoras's theorem, Heron's rule, and rotation matrices, so a detailed explanation will be omitted. The processor 21 stores the calculated position (coordinate) S of the wireless tag 3 in the memory 22.

[0094] (Step S812) The processor 21 controls the display 14 so as to notify the operator of the position (coordinates) of the wireless tag 3. As a result, the display 14 displays the position (coordinates) of the wireless tag 3. Note that the notification of the position (coordinates) of the wireless 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 wireless tag 3 via an audio device.

[0095] As described above, the radio tag communication device 1 of this embodiment communicates with the radio tag 3 via the communicator 23, detects the position of the communicator 23 using a position detection sensor, and identifies the position of the radio tag 3 based on the phase of the radio waves collected through communication between the radio tag 3 and the communicator 23.The radio tag communication device 1 identifies the midpoint of two positions where the phases obtained when the communicator 23 moves on the arc ARC are the same as the first position A, identifies a position on the movement path on the arc ARC that is different from the first position A as the second position B, calculates the central angle θ of the sector OAB formed by the first position A, the second position B, and the arc ARC, and identifies the position of the radio tag 3 using the central angle θ, the first position A, and the second position B.

[0096] For example, in the radio tag communication device 1 according to this embodiment, a first position A, a second position B, and a center point O of the arc ARC form an isosceles triangle OAB, and the radio tag communication device 1 calculates a first distance L between the radio tag 3 and the first position A using the exterior angle (θ+a) of the isosceles triangle OAB when a side OA including the center point O is extended toward the radio tag 3, and identifies the position S of the radio tag 3 using the first distance L. Specifically, the radio tag communication device 1 according to this embodiment identifies the position S of the radio tag 3 based on the first distance L, a second distance Lr between the first position A and the second position B, and the amount of phase change (corresponding to Li) between the first position A and the second position B.

[0097] More specifically, the radio tag communication device 1 of this embodiment uses the phase change to calculate a first difference Li between the distance from the radio tag 3 to the second position B and the first distance L, calculates a second distance Lr using the first position A and the second position B, calculates the first distance L using the second distance Lr, the first difference Li, and the exterior angle (θ+a), calculates a first angle η (∠SBA) between the side AB connecting the first position A and the second position B and the side SB connecting the radio tag 3 and the second position B using the first distance L, the second distance Lr, and the first difference Li, and identifies the position S of the radio tag 3 using the second distance Lr, the exterior angle (θ+a), and the first angle η.

[0098] For these reasons, the RFID tag communication device 1 according to this embodiment can calculate the position S of the RFID tag 3 using only actual measurement values. Therefore, the RFID tag communication device 1 according to this embodiment can estimate the position S of the RFID tag 3 with high accuracy. In addition, the RFID tag communication device 1 according to this embodiment can calculate the first distance L using the coordinates of the target tag S and the coordinates of the first position A, so that in searching for the target tag S, the direction from its own position to the search object can be determined using the first distance L based on actual measurement rather than assumption. For these reasons, the RFID tag communication device 1 according to this embodiment can accurately determine information related to the search for the target tag 3 (the position of the search object and the direction from its own position to the search object), thereby improving the efficiency of the search for the target tag 3.

[0099] (Application example) In this application example, when searching for a target tag, the position of the target tag is recalculated and updated in accordance with the movement of the RFID tag communication device 1 or the reader device 10. The procedure for tag position estimation processing in this application example will be described below. Figures 9 and 10 are flowcharts showing an example of the procedure for tag position estimation processing in this application example.

[0100] Note that steps S901 to S903 in Fig. 9 are similar to steps S801 to S803 in Fig. 8, and therefore their explanations will be omitted. Also, steps S905 to S912 in Fig. 9 are similar to steps S804 to S811 in Fig. 8, and therefore their explanations will be omitted. Also, step S919 in Fig. 10 is similar to step S812 in Fig. 8, and therefore its explanation will be omitted. As shown in Figs. 9 and 10, after the processing of step S912, the processing of step S919 is executed.

[0101] (Tag position estimation process) (Step S904) The processor 21 determines whether or not there is an estimation result (coordinates) of the position S of the target tag. If the estimation result (coordinates) of the position S of the target tag is not stored in the memory 22 (Yes in step S904), the processing of step S905 and subsequent steps is executed. If the estimation result (coordinates) of the position S of the target tag is stored in the memory 22 (No in step S904), the processing of step S913 is executed. Prior to the processing of step S913, the wireless tag communication device 1 or the reader device 10 is moved toward the wireless tag 3.

[0102] (Step S913) In the radio tag communication device 1 or reader device 10 after movement, the communicator 23 communicates with the radio tag 3 at a third position different from the first position A and the second position B. The position detection sensor detects the position (third position) of the radio tag communication device 1 or reader device 10 after movement toward the radio tag 3. The processor 21 estimates its own position (coordinates) at the third position based on the output from the position detection sensor.

[0103] (Step S914) After the wireless tag communication device 1 or the reader device 10 moves from the first position to the third position, the processor 21 calculates a second difference between the first distance L and the distance from the wireless tag 3 to the third position, using the amount of change in phase of the radio waves collected by communication between the wireless tag 3 and the communicator 23 at the first position A and the third position. In general, the processor 21 calculates the second difference indicating the difference between the distance between the position before moving to the third position and the wireless tag 3, and the distance between the wireless tag 3 and the third position. The second difference corresponds to the new distance Li.

[0104] (Step S915) After the RFID tag communication device 1 or the reader device 10 moves from the first position to the third position, the processor 21 uses the first position A and the third position to calculate a third distance between the first position A and the third position. In general, the processor 21 calculates the third distance between the position before moving to the third position and the third position. The third distance corresponds to the new distance Lr.

[0105] (Step S916) After the RFID tag communication device 1 or the reader device 10 moves from the first position to the third position, the processor 21 calculates a second angle between the side connecting the first position A and the third position and the side connecting the RFID tag 3 and the third position using the first distance L, the third distance (new Lr), and the second difference (new Li). The second angle is calculated using equation (1) or equation (2). In this case, the second angle corresponds to a corner at one end of new Lr.

[0106] Furthermore, after the RFID tag communication device 1 or the reader device 10 moves from the first position A to the third position, the processor 21 uses the first distance L, the third distance (new Lr), and the second difference (new Li) to calculate a third angle between the side connecting the first position A and the third position and the side connecting the RFID tag 3 and the first position A. Equation (1) or (2) is used to calculate the third angle. In this case, the third angle corresponds to the corner at the other end of new Lr.

[0107] Generally, in a triangle formed by the position before movement, the third position, and the wireless tag 3, the processor 21 calculates the angles at both ends of the third distance using the distance between the position before movement and the wireless tag 3, the third distance, and the second difference. Equations (1) and (2) are used to calculate the angles at both ends of the third distance.

[0108] (Step S917) The processor 21 uses the third distance and the angles at both ends of the third distance to calculate the position of the wireless tag 3. The method of calculating the position (coordinates) of the wireless tag 3 is the same as in step S811, and therefore description thereof will be omitted.

[0109] (Step S918) The processor 21 replaces the position (coordinates) of the wireless tag 3 stored in the memory 22 with the newly calculated position (coordinates) of the wireless tag 3. As a result, the position (coordinates) of the wireless tag 3 stored in the memory 22 is updated to the newly calculated position (coordinates) of the wireless tag 3.

[0110] (Step S920) The processor 21 determines whether or not the search object has been detected. For example, the processor 21 uses the newly calculated position of the wireless tag 3 and the third position to calculate the distance between the newly calculated position of the wireless tag 3 and the third position. If the calculated distance is equal to or less than a predetermined value (for example, 50 cm), the processor 21 determines that the search object has been detected. The predetermined value is set in advance and stored in the memory 22. If the search object has been detected (Yes in step S920), the tag position estimation process ends.

[0111] If the calculated distance exceeds a predetermined value (for example, 50 cm), processor 21 determines that the search object has not been detected. If the search object has not been detected (No in step S920), the processes from step S903 onwards are repeated.

[0112] As described above, the wireless tag communication device 1 according to the application example of this embodiment communicates with the wireless tag 3 at a third position different from the first position A and the second position B, detects the third position, calculates a second difference (new Li) between the first distance L and the distance from the wireless tag 3 to the third position using the amount of change in phase of the radio waves collected by communication between the wireless tag 3 and the communicator 23 at the first position A and the third position, calculates a third distance (new Lr) between the first position A and the third position using the first position A and the third position, and Using the distance L, the third distance (new Lr), and the second difference (new Li), a second angle (a corner at one end of the new Lr) between the side connecting the first position A and the third position and the side connecting the wireless tag 3 and the third position is calculated, and using the first distance L, the third distance (new Lr), and the second difference (new Li), a third angle (a corner at the other end of the new Lr) between the side connecting the first position A and the third position and the side connecting the wireless tag 3 and the first position A is calculated, and the position of the wireless tag 3 is identified using the third distance, the second angle, and the third angle.

[0113] According to the RFID tag communication device 1 of the application example of this embodiment, the position of the target tag 3 can be recalculated and updated in accordance with the movement of the RFID tag communication device 1 or the reader device 10. As a result, according to the RFID tag communication device 1 of the application example of this embodiment, the position of the target tag 3 can be updated every time the RFID tag communication device 1 or the reader device 10 approaches the RFID tag 3, and therefore the accuracy of the position of the target tag 3 can be improved in accordance with the movement of the RFID tag communication device 1 or the reader device 10. Other effects are the same as those of the embodiment, and therefore description thereof will be omitted.

[0114] When the technical idea of ​​the embodiment is realized by a program, the program causes a computer to communicate with a wireless tag 3 via a communicator 23, detect the position of the communicator 23, and identify the position of the wireless tag 3 based on the phase of the radio waves collected by communication between the wireless tag 3 and the communicator 23. The program causes the computer to identify the midpoint of two positions where the phases obtained when the communicator 23 moves on the arc ARC match as a first position A, identify a position on the movement path of the communicator 23 on the arc ARC that is different from the first position A as a second position B, calculate the central angle θ of a sector formed by the first position A, the second position B, and the arc ARC, and identify the position of the wireless tag 3 using the central angle θ, the first position A, and the second position B.

[0115] For example, the 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 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 on a storage medium such as a magnetic disk (such as a hard disk), an optical disk (such as a CD-ROM or DVD), or a semiconductor memory. Furthermore, the distribution of the program is not limited to the above-mentioned media, and it may be distributed using an electronic 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.

[0116] 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]

[0117] 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) 31 processors 32 memory 33 Interface 34 Sensor (position detection sensor) 35 Camera (position detection sensor) [Prior art documents] [Patent documents]

[0118] [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 processor for identifying the location of the wireless tag based on the phase of radio waves collected through communication between the wireless tag and the communicator; Equipped with The processor: identifying, as a first position, a midpoint between two positions where the phases obtained while the communication device is moving on an arc coincide with each other; Identifying a position on the arcuate movement path that is different from the first position as a second position; calculating a central angle of a sector formed by the first position, the second position, and the arc; identifying the position of the wireless tag using the central angle, the first position, and the second position; Radio tag communication device.

2. the first position, the second position, and the center point of the arc form an isosceles triangle; The processor: calculating a first distance between the wireless tag and the first position using an exterior angle of the isosceles triangle when a side including the center point is extended toward the wireless tag; using the first distance to identify the location of the wireless tag; The radio tag communication device according to claim 1 .

3. The processor: identifying the position of the wireless tag based on the first distance, a second distance between the first position and the second position, and the amount of change in the phase between the first position and the second position; The radio tag communication device according to claim 2 .

4. The processor: calculating a first difference between the distance from the wireless tag to the second position and the first distance using the amount of change in the phase; calculating the second distance using the first position and the second position; calculating the first distance using the second distance, the first difference, and the exterior angle; calculating a first angle between a side connecting the first position and the second position and a side connecting the wireless tag and the second position using the first distance, the second distance, and the first difference; identifying a position of the wireless tag using the second distance, the exterior angle, and the first angle; The radio tag communication device according to claim 3 .

5. the communicator communicates with the wireless tag at a third location different from the first location and the second location; the position detection sensor detects the third position; The processor: calculating a second difference between the first distance and the distance from the wireless tag to the third position using a change in phase of radio waves collected by communication between the wireless tag and the communicator at the first position and the third position; calculating a third distance between the first position and the third position using the first position and the third position; calculating a second angle between a side connecting the first position and the third position and a side connecting the wireless tag and the third position using the first distance, the third distance, and the second difference; calculating a third angle between a side connecting the first position and the third position and a side connecting the wireless tag and the first position using the first distance, the third distance, and the second difference; identifying a position of the wireless tag using the third distance, the second angle, and the third angle; The radio tag communication device according to claim 4.

6. On the computer, Communicate with the wireless tag via the communication device, Detecting the location of the communicator; a program for executing a process of identifying a position of the wireless tag based on a phase of radio waves collected through communication between the wireless tag and the communication device, The program causes the computer to: identifying, as a first position, a midpoint between two positions where the phases obtained while the communication device is moving on an arc coincide with each other; Identifying a position on the arcuate movement path that is different from the first position as a second position; calculating a central angle of a sector formed by the first position, the second position, and the arc; identifying the position of the wireless tag using the central angle, the first position, and the second position; A program to make this happen.

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