Wireless tag communication device and program

Abstract

To provide a wireless tag communication device and a program capable of identifying the location of a wireless tag with high accuracy.SOLUTION: According to an embodiment, a wireless tag communication device includes a communicator, a position detection sensor, a memory, and a processor. The communicator communicates with a target wireless tag. The position detection sensor detects information indicating its self-position. The memory stores the self-position identified from information detected by the position detection sensor and a read result of the wireless tag read by the communicator in association with each other. The processor estimates the position of the wireless tag from read results obtained by reading the wireless tag at three different self-positions including a self-position that is at an end point of a distance stored in the memory, using a processing method selected according to the distance between the self-position identified from the information detected by the position detection sensor and the estimated position of the wireless tag.SELECTED DRAWING: Figure 2

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 is a wireless tag communication device that aims to find an RFID tag (hereinafter, also referred to as a wireless tag) in an unspecified location. The wireless tag communication device communicates with the RFID tag while changing the position and orientation of the antenna by the operation of an operator. The conventional wireless tag communication device estimates the direction in which the RFID tag to be searched for is located based on the communication state with the RFID tag to be searched for.

[0003] Conventional radio tag communication devices notify an operator of the direction in which an RFID tag is located by displaying on a display a guidance screen including an estimation result of the direction in which an RFID tag is located. The operator searches for an RFID tag or an item to which an RFID tag is attached while moving in the direction displayed on the display. However, conventional radio tag communication devices only notify the direction in which an RFID tag is located, and do not notify the position of the RFID tag being searched for. For this reason, conventional radio tag communication devices have a problem in that operators who are unfamiliar with the operation take a long time to find an RFID tag. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2011-237941 A Summary of the Invention [Problem to be solved by the invention]

[0005] In order to solve the above-mentioned problems, an object of the present invention is to provide a radio tag communication device and a program that can accurately identify the location of a radio tag. [Means for solving the problem]

[0006] According to an embodiment, a wireless tag communication device includes a communicator, a position detection sensor, a memory, and a processor. The communicator communicates with a target wireless tag. The position detection sensor detects information indicating its own position. The memory stores the self-position determined from the information detected by the position detection sensor in association with a reading result of the wireless tag read by the communicator. The processor estimates the position of the wireless tag from the reading result of the wireless tag read at three different self-positions including the self-position that is an end point of the distance stored in the memory, using a processing method selected according to a distance between the self-position determined from the information detected by the position detection sensor and the estimated position of the wireless tag. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is an external view showing an example of the external configuration of a radio tag communication device according to an embodiment. [Diagram 2] FIG. 2 is a block diagram illustrating a first example of the configuration of a control system in the wireless tag communication device according to the embodiment. [Diagram 3] FIG. 3 is a block diagram illustrating a second exemplary configuration of the control system in the wireless tag communication device according to the embodiment. [Figure 4] FIG. 4 is a diagram showing an example of positional relationships when the wireless tag communication device according to the embodiment reads tags to be searched at three different positions. [Diagram 5] FIG. 5 is a diagram showing an example of a table showing angles relative to the ratio of the movement distance of the device for communicating with a wireless tag according to the embodiment to the distance approached to the tag. [Figure 6] FIG. 6 is a diagram showing an example of a graph showing an angle versus a ratio between a moving distance of the device for communicating with a wireless tag according to the embodiment and a distance approaching the tag. [Figure 7] FIG. 7 is a diagram showing an example of a graph showing an angle versus a ratio of a moving distance to a tag and a distance approaching the tag for each distance to the tag in the device for communicating with a wireless tag according to the embodiment. [Figure 8]FIG. 8 is a diagram showing an example in which the wireless tag communication device according to the embodiment sets an angle determination table according to the distance to the tag. [Figure 9] FIG. 9 is a flowchart for explaining an example of operation of a first tag search process including an angle estimation process using a table by the wireless tag communication device according to the embodiment. [Figure 10] FIG. 10 shows a graph and a relational expression showing the relationship between the ratio Li / Lr and the angle when the distance to the tag of the wireless tag communication device according to the embodiment is 1 m. [Figure 11] FIG. 11 shows a graph and a relational expression showing the relationship between the ratio Li / Lr and the angle D when the distance to the tag of the wireless tag communication device according to the embodiment is 3 m. [Figure 12] FIG. 12 shows a graph and a relational expression showing the relationship between the ratio Li / Lr and the angle D when the distance to the tag of the wireless tag communication device according to the embodiment is 5 m. [Figure 13] FIG. 13 shows a graph and a relational expression showing the relationship between the ratio Li / Lr and the angle D when the distance to the tag of the wireless tag communication device according to the embodiment is 7 m. [Figure 14] FIG. 14 is a diagram showing an example of a calculation formula set by the wireless tag communication device according to the embodiment for each distance to the tag. [Figure 15] FIG. 15 is a flowchart for explaining an example of operation of a second tag search process including an angle estimation process using a calculation formula by the wireless tag communication device according to the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, embodiments will be described with reference to the drawings. First, the configuration of a radio tag communication device (radio tag reader) 1 according to the embodiment will be described. Fig. 1 is a diagram showing an example of the external configuration of a radio tag communication device 1 according to an embodiment. The radio 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 tag communication device 1 shown in Fig. 1 is used as a search device that searches for an RFID tag or an article to which an RFID tag is attached, for example.

[0009] The wireless tag communication device 1 according to the embodiment is a device that communicates with an RFID tag (wireless tag). The wireless tag communication device 1 is a wireless tag reading device that reads tag information recorded in an RFID tag by communicating with the RFID tag. The wireless tag communication device 1 estimates the location of the RFID tag from the RFID tag reading result. The wireless tag communication device 1 displays a guidance screen on a display device that shows information related to the estimated location of the RFID tag.

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

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

[0012] The wireless tag communication device 1 according to the embodiment reads an RFID tag attached to an item while changing its position and orientation by an operation of an operator. For example, the wireless tag communication device 1 is operated as a search device for searching for an item with an RFID tag attached within a predetermined area (search range) such as a warehouse or a store. The wireless tag communication device 1 as a search device continuously reads the RFID tag to be searched while changing its position by an operation of an operator.

[0013] The wireless tag communication device 1 reads tag information recorded in an RFID tag by receiving a response signal from the RFID tag present within a reading area (reading range). Furthermore, the wireless tag communication device 1 also obtains information such as an RSSI value and a phase value from the response (received) signal from the RFID tag. The wireless 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 device itself, in a memory as a reading result.

[0014] 1, the radio tag communication device 1 is composed of a reader device (base device) 10 and an information terminal device 13 serving as a user interface. The reader device 10 may be provided as the radio tag communication device 1. In this case, the radio tag communication device 1 serving as the reader device 10 is operated with the information terminal device 13 serving 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 the arrow a shown in Fig. 1. Here, the direction of the arrow a is assumed to be the front (forward) direction of the wireless tag communication device 1. Also, the front direction of the wireless tag communication device 1 is assumed to be the orientation of the antenna.

[0016] The reader device 10 has a gripping unit 11 and a holding unit 12 in addition to a control system configuration described later. The gripping unit 11 is a part that is held by an operator. The holding unit 12 is configured by 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 wireless tag communication device 1 is operated by an operator 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, an operator can view a screen displayed by the display unit 14. When the information terminal device 13 is set in the holding unit 12 of the reader device 10, an operator inputs an operation instruction to the input unit 15.

[0018] The radio tag communication device 1 continuously reads RFID tags while being operated by an operator. 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 RFID tags within a reading area set by the direction of the antenna and the strength of the radio waves output from the antenna while estimating the position of the device itself.

[0019] The wireless tag communication device 1 estimates its own position using a self-estimation technique. For example, the wireless 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. However, the technique and configuration for estimating the position of the own device used in the wireless tag communication device 1 are not limited to a specific one as long as the device can estimate its own position even indoors.

[0020] The wireless tag communication device 1 determines whether or not a search target RFID tag is present in a read area based on the RFID tag read results in the read area set by the antenna direction and the strength of the radio waves output from the antenna. For example, the wireless tag communication device 1 stores in memory the read results of the RFID tag to be searched in a plurality of read areas based on the positions of the plurality of moved devices. For example, the wireless tag communication device 1 stores in memory information such as tag information, phase value, antenna direction, and output value as the RFID tag read results. The wireless tag communication device 1 stores in memory the read results including the tag information of the search target RFID tag as the read result of a specific RFID tag in association with information indicating its own position (position information).

[0021] The wireless tag communication device 1 estimates the location of the RFID tag to be searched for based on the read results at multiple different self-positions stored in the memory. For example, the wireless tag communication device 1 estimates the location (tag location) of the RFID tag to be searched for based on the read results of the RFID tag to be searched for at three or more different self-positions at a predetermined interval.

[0022] Next, the configuration of a control system in the wireless tag communication device 1 according to the embodiment will be described. FIG. 2 is a block diagram showing a first example of the configuration of a control system in the wireless tag communication device 1 according to the embodiment. In the exemplary configuration shown in FIG. 2, the RFID tag communication device 1 has a processor 21, a memory 22, a RFID tag communication unit 23, a sensor 24, a communication interface (I / F) 25, a camera 26, a display 14, and an input device 15.

[0023] The processor 21 controls each unit. The processor 21 includes 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.

[0024] The memory 22 includes various types of memories. 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 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 a buffer memory.

[0025] The NVM of the memory 22 is a rewritable non-volatile memory. The memory 22 saves information such as control information, setting information, and processing results in the NVM. The memory 22 also stores in the NVM various programs 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 for assisting an operator in operating the housing. The memory 22 also stores in the NVM an evaluation reference value for the operation assistance program to evaluate the operation of the housing.

[0026] The wireless tag communication unit 23 is a communication device constituting an RFID interface that communicates with an RFID tag. The wireless tag communication unit 23 is, for example, a communication device having a communication control circuit and an antenna. However, the wireless tag communication unit 23 may 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 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. The wireless tag communication unit 23 sets a range (read area, read range) in which the RFID tag can respond based on the orientation of the antenna and the output value of the radio wave output from the antenna.

[0028] In addition, in the wireless 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 by the antenna, processes the response signal (received signal) received by the antenna, and supplies it 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, and an RSSI value and a phase value indicating the strength of the received signal.

[0029] The sensor (sensor group) 24 detects the position or a change in position of the wireless tag communication device 1. For example, the sensor 24 is an acceleration sensor, a gyro sensor, or a geomagnetic (direction) sensor. The sensor 24 may include a plurality of 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 that detects information indicating its own position (position of the communicator).

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

[0031] The camera 26 captures an image. The capturing direction of the camera 26 changes depending on the orientation of the wireless tag communication device 1. For example, the capturing direction of the camera 26 may be set to match the orientation of the antenna of the wireless tag communication unit 23. The image captured by the camera 26 is used to estimate the position of the wireless tag communication device 1 (the position of the device itself). The camera 26 is an example of a position detection sensor that detects information indicating its own position (the position of the communicator). For example, the wireless tag communication device 1 estimates its own position (the position of its own device) based on the image captured by the camera 26 by a self-position estimation method used in AR (Augmented Reality) technology.

[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 input device 15 is a device that allows an operator to input operation instructions and the like. The input device 15 supplies the processor 21 with information indicating the contents of the instructions given by the operator.

[0033] The radio tag communication device 1 has a power source that supplies power for operation. In a handheld type radio tag communication device 1, for example, a rechargeable battery (secondary battery) is provided as the power source. The battery supplies each part of the radio tag communication device 1 with power to operate the parts. The radio tag communication device 1 may also be configured such that the camera 26 is replaced with a device for identifying the position of the device itself.

[0034] Next, the configuration of a control system in the wireless tag communication device 1 according to the embodiment will be described. FIG. 3 is a block diagram showing a second example of the configuration of the control system in the wireless tag communication device 1 according to the embodiment. 3, a reader device 10 serving as the wireless tag communication device 1 is connected to an information terminal device 13 serving as an external device. The reader device 10 serving as the wireless tag communication device 1 includes a processor 21, a memory 22, a wireless tag communication unit 23, and an interface (I / F) 26.

[0035] The processor 21 controls each unit. The processor 21 includes 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.

[0036] The memory 22 includes various kinds of memories. 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 executed by the processor 21. The RAM is a volatile memory that temporarily stores data. The RAM operates as a working memory or a buffer memory. The NVM is a non-volatile memory that can be rewritten. 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 later.

[0037] The wireless tag communication unit 23 is a communication device that constitutes an RFID interface that communicates with an RFID tag. The wireless tag communication unit 23 is a communication device that has a communication control circuit and an antenna. However, the wireless tag communication unit 23 may be configured as a connection interface that connects to an external antenna.

[0038] In the wireless tag communication unit 23, the communication control circuit includes a control circuit for communicating with the RFID tag 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. The wireless tag communication unit 23 sets a range (read area) in which the RFID tag can respond based on the orientation of the antenna and the output value of the radio wave output from the antenna.

[0039] In addition, in the wireless 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 by the antenna, processes the response signal (received signal) received by the antenna, and supplies it 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, and an RSSI value and a phase value indicating the strength of the received signal.

[0040] 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 an interface that physically contacts and connects to an interface included in the information terminal device 13, such as a Universal Serial Bus (USB) interface or a LAN interface. The interface 26 may also be an interface that wirelessly connects for communication, such as a Bluetooth (registered trademark) interface or a Wifi (registered trademark) interface.

[0041] The reader device 10 as the radio tag communication device 1 has a power source 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 source. The battery supplies each part of the radio tag communication device 1 with power for operating the parts.

[0042] 3, the information terminal device 13 is set in a holder 12 of a reader device 10 serving as a wireless 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 a wireless 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.

[0043] 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, an input device 15, and the like. 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.

[0044] 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 Wifi.

[0045] The sensor (sensor group) 34 includes a sensor that detects the position or a change in position of the information terminal device 13. For example, the sensor 34 is an acceleration sensor, a gyro sensor, or a geomagnetic (direction) sensor. The sensor 34 may include a plurality of types of sensors. The sensor 34 may include a position detection sensor for detecting the position. In this case, the sensor 34 is an example of a position detection sensor that detects information indicating the self-position (position of the communicator). Note that some or all of the sensors as the sensor 34 described above may be provided in the reader device 10.

[0046] The camera 35 captures an image. The image capturing direction of the camera 35 changes according to 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 included in the reader device 10.

[0047] The image captured by the camera 35 is used to estimate the position (position of the device itself) of the information terminal device 13 (wireless tag communication device 1 consisting of a reader device 10 in which the information terminal device 13 is set). The camera 35 is an example of a position detection sensor that detects information indicating its own position (position of the communicator). 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 by a self-position estimation method used in AR (Augmented Reality) technology.

[0048] 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. As described above, the wireless tag communication unit (communicator) 23 has a communication control circuit and an antenna. The communication control circuit of the wireless 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 wireless 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. The communication control circuit processes signals to be transmitted to the RFID tag via the antenna and signals received from the RFID tag.

[0049] 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.

[0050] The RFID tag receives radio waves as a transmission signal transmitted from the antenna. The RFID tag recognizes, for example, a read command contained in the transmission signal transmitted from the antenna. When the RFID tag recognizes the read command, it outputs data (tag information) stored in its own memory by radio waves, for example by backscatter modulation.

[0051] The antenna receives radio waves as a reception signal output by the RFID tag. The communication control circuit acquires the reception signal received by the antenna using a coupler and supplies the acquired reception signal to the 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.

[0052] The antenna of the radio tag communication unit 23 has directionality and is installed at a predetermined position of the radio tag communication device 1 facing a predetermined direction. The antenna is, for example, a planar antenna. However, the antenna of the radio tag communication unit 23 is not limited to a specific configuration. The antenna is placed in the housing so as to transmit electromagnetic waves (output signals) toward a communication area (reading area) centered on the direction where the directivity is maximum (for example, direction a shown in FIG. 1). The radio tag communication device 1 is configured so that the direction where the antenna's directivity is maximum is the front (direction a shown in FIG. 1).

[0053] 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 transmitting amplifier circuit amplifies the signal supplied from the modulation circuit to the output value set by the output setting circuit. The antenna transmits an output signal (radio wave) of the output value set by the output setting circuit, which is supplied from the transmitting amplifier circuit via a coupler.

[0054] The wireless tag communication unit 23 sets a range (reading area) in which radio waves to which an RFID tag can respond are transmitted according to the direction 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 according to the direction 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 according to instructions from the processor 21.

[0055] The communication control circuit of the wireless 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. For example, the communication control circuit of the wireless tag communication unit 23 detects information for identifying the RSSI value indicating the strength of the received signal (response signal from the RFID tag) 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 wireless 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.

[0056] Next, a tag position estimation process for estimating the position of an RFID tag (hereinafter, referred to as a target tag) that is a search target of the wireless tag communication device 1 according to the embodiment will be described. The wireless tag communication device 1 reads the target tag while moving from position to position (own position) while being held by an operator. The wireless tag communication device 1 estimates (determines) the direction of the target tag at multiple positions, and estimates the position of the target tag based on the direction of the target tag from the multiple positions. The wireless tag communication device 1 obtains the read results of the target tag read at multiple positions (own position). The wireless tag communication device 1 estimates the direction of the target tag from each position based on the read result at each position and the read result at the next position. Furthermore, the wireless tag communication device 1 estimates the position of the target tag based on the direction of the target tag from the multiple positions.

[0057] FIG. 4 is a diagram showing an example of positional relationships when the wireless tag communication device 1 reads the RFID tag O to be searched for at three different positions. 4, it is assumed that the wireless tag communication device 1 reads the target tag O at a first position Pa, a second position Pb, and a third position Pc. For example, an operator holding the wireless tag communication device 1 reads the target tag O while moving in order among the first position Pa, the second position Pb, and the third position Pc.

[0058] The processor 21 of the wireless tag communication device 1 stores read information including the position of the device itself and the phase of the received signal as a result of reading the target tag at each position in the memory 22. The processor 21 determines the distance Lr between the first position Pa and the second position Pb from the read information at the first position Pa and the read information at the second position Pb. The processor 21 also determines the differential distance Li between the distance PaO from the first position Pa to the target tag O and the distance PbO from the second position Pb to the target tag O.

[0059] The differential distance Li is calculated from the difference (phase difference) between the phase of the received signal (response wave) received at the first position Pa and the phase of the signal (response wave) received at the second position Pb. In other words, the differential distance (Li=La-LB) between the distance La from the first position Pa to the target tag O and the distance Lb from the second position Pb to the target tag O appears as a phase difference (amount of phase change). Thus, the processor 21 determines the differential distance Li from the phase difference obtained from the read information at the first position Pa and the read information at the second position Pb.

[0060] The processor 21 derives (estimates) the angle D of the angle OAB from the ratio Li / Lr between the distance Lr and the difference distance Li. Here, the angle D derived (estimated) from the ratio Li / Lr is stored in advance as an angle determination table in the memory 22. After calculating the ratio Li / Lr, the processor 21 determines the angle D corresponding to the calculated Li / Lr based on the angle determination table.

[0061] 4, angle OPaPb is angle D formed by line segment PaPb and line segment PaO. Therefore, when the positions (position coordinates) of position Pa and position Pb are specified, the direction from position Pa to target tag O (a straight line passing through position Pa and target tag O) can be specified. Processor 21 determines the direction from position Pa to target tag O based on angle D of angle OAB determined from ratio Li / Lr.

[0062] Using a method similar to that described above, the processor 21 determines the distance Lr' between the second position Pb and the third position Pc from the read information at the second position Pb and the read information at the third position Pc. The processor 21 determines the differential distance Li' between the distance PbO from the second position Pb to the target tag O and the distance PcO from the third position Pc to the target tag O. The differential distance Li' is determined by the phase difference obtained from the read information at the second position Pc and the read information at the third position Pc.

[0063] The processor 21 calculates the ratio Li' / Lr' between the distance Lr' and the differential distance Li', and determines the angle D' corresponding to the calculated Li' / Lr' based on an angle determination table. The processor 21 determines the direction of the target tag O from the second position Pb (a straight line passing through the position Pb and the target tag O) based on the angle D' of the angle OPbPc determined from the ratio Li' / Lr'.

[0064] The processor 21 determines (estimates) the position of the target tag O based on the direction of the target tag from the first position Pa and the direction of the target tag from the second position Pb. For example, the processor 21 determines the intersection of a straight line PaO passing through the first position Pa and the target tag O and a straight line PbO passing through the second position Pb and the target tag O as the position of the target tag O.

[0065] That is, the RFID tag communication device 1 determines (estimates) the direction from one position to the target tag from the read information of the target tag at two positions. The RFID tag communication device 1 reads the target tag at three or more positions and determines the directions from the multiple positions to the target tag. The RFID tag communication device 1 determines the position of the target tag based on the directions from the multiple positions to the target tag.

[0066] Next, an angle determination table for the RFID tag communication device 1 to determine the direction of the target tag will be described. Fig. 5 is a table showing the relationship between the ratio Li / Lr of the distance Lr between two positions to the difference (difference distance) Li between the distances from the two positions to the target tag, and the angle D. In Fig. 5, the distance Lr corresponds to the movement distance of the wireless tag communication device 1 (movement distance of its own position), and the distance Li corresponds to the distance (difference distance) by which the wireless tag communication device 1 approaches the target tag.

[0067] The table shown in Fig. 5 records each value in two-dimensional coordinates with the position of the search object (target tag) as the origin O (0, 0) and the coordinates of reference position A as (0, 8). (X, Y) in Fig. 5 indicates the coordinates of variable position B when the moving distance Lr from reference position A is 0.5 m. The angle in Fig. 5 is the angle (angle OAB) between the straight line connecting the target tag position O and reference position A and the straight line connecting reference position A and variable position B. The distance in Fig. 5 indicates the distance between variable position B and the target tag position O.

[0068] The differential distance Li in Fig. 5 is the distance (Li = La - Lb) obtained by subtracting the distance Lb between the target tag's position O and the variable position B from the distance La between the target tag's position O and the reference position A. The differential distance Li is a distance calculated from the amount of phase change between the phase of the signal received from the target tag at the reference position A and the phase of the signal received from the target tag at the variable position B. The ratio Li / Lr in Fig. 5 is the ratio between the moving distance Lr and the differential distance Li.

[0069] Fig. 6 is a graph showing the relationship between the angle specified based on the values ​​shown in Fig. 5 and the ratio Li / Lr. According to the table shown in Fig. 5 or the graph shown in Fig. 6, the angle of the angle OAB can be determined from the ratio Li / Lr. In other words, when the coordinates of position A and the coordinates of position B and the angle of the angle OAB are specified, the direction in which the target tag is located from position A can be determined even if the coordinates of the target tag are not known.

[0070] By using the table shown in Fig. 5 or the graph shown in Fig. 6, the angle D shown in Fig. 4 can be calculated from the movement distance Lr and the difference distance Li. Similarly, the angle D' shown in Fig. 4 can be calculated from the movement distance Lr' and the difference distance Li'. As a result, the position of the target tag shown in Fig. 4 can be determined based on the direction from position Pa to the target tag (angle D) and the direction of the target tag from the second position Pb (angle D').

[0071] As described above, the wireless tag communication device 1 can estimate the tag position by calculating the angle D from Li / Lr using the relationship shown in the table of Fig. 5 or the graph of Fig. 6. However, Fig. 5 shows the relationship between the ratio Li / Lr and the angle D when the position of the target tag is assumed to be the origin O (0, 0) and the coordinates of the reference position A are assumed to be (0, 8). In general, when the distance between the target tag and the reference position (self-position) changes, the relationship between the ratio Li / Lr and the angle D changes.

[0072] Fig. 7 is a graph showing the relationship between the ratio Li / Lr of the movement distance Lr and the difference distance Li, and the angle D when the distance between the target tag and the reference position (self-position) is varied. As a specific example, Fig. 7 shows a graph showing the relationship between the ratio Li / Lr and the angle D when the distance between the target tag and the reference position is 7 m, 5 m, 3 m, and 1 m. As shown in Fig. 7, when the distance between the target tag and the reference position (i.e., the distance to the target tag) varies, the relationship between the ratio Li / Lr and the angle D varies.

[0073] When actually searching for a target tag, the distance between the position (self-position) of the RFID tag communication device 1 held by the operator and the target tag varies. For example, in searching for a target tag, it is assumed that the operator holding the RFID tag communication device 1 approaches the target tag by referring to the tag position displayed on the display 14. For this reason, in actual operation, the closer to the target tag, the higher the angle estimation accuracy (position estimation accuracy) is required.

[0074] In order to improve the accuracy of estimating the position of the target tag, the wireless tag communication device 1 according to the embodiment sets a relationship (data table or calculation formula) between the ratio Li / Lr and the angle D according to the distance between the target tag and its own position. The wireless tag communication device 1 estimates the angle D from the ratio Li / Lr using the relationship selected depending on the distance between the target tag and its own position.

[0075] Hereinafter, a first processing example and a second processing example will be described in which the RFID tag communication device 1 according to the embodiment estimates a tag position using a relationship according to the distance to the target tag. First, as a first processing example, a first tag search process in which a tag position estimation process is performed using an angle determination table according to the distance to the target tag will be described. In the first tag search process, the wireless tag communication device 1 executes the tag position estimation process using a data table (angle determination table) indicating the relationship between the ratio Li / Lr and the angle D. The wireless tag communication device 1 also stores a plurality of angle determination tables set for each distance to the target tag in the memory 22. The wireless tag communication device 1 executes the tag position estimation process using the angle determination table selected according to the distance to the target tag.

[0076] FIG. 8 is a diagram showing an example in which an angle determination table is set according to the distance L to the tag estimated position. The example shown in Figure 8 shows an angle determination table when the distance L to the target tag is divided into the following ranges: 1.5 m or less, 1.5 to 2.5 (2 ± 0.5) m, 2.5 to 3.5 (3 ± 0.5) m, 3.5 to 4.5 (4 ± 0.5) m, 4.5 to 5.5 (5 ± 0.5) m, 5.5 to 6.5 (6 ± 0.5) m, 6.5 to 7.5 (7 ± 0.5) m, and 7.5 m or more.

[0077] The wireless tag communication device 1 estimates the distance to the tag position and selects an angle determination table according to the distance to the tag position. The wireless tag communication device 1 estimates the angle D from Li / Lr using the selected angle determination table. For example, when the distance L to the target tag is 1 m, the wireless tag communication device 1 selects an angle determination table of 1.5 m or less. In this case, the wireless tag communication device 1 estimates the angle D from the ratio Li / Lr using the angle determination table of 1.5 m or less.

[0078] Next, a tag search process (first tag search process) including angle estimation using a table by the wireless tag communication device 1 according to the embodiment will be described.

[0079] FIG. 9 is a flowchart for explaining an operation example of a first tag search process including an angle estimation process using a table by the wireless tag communication device 1 according to the embodiment. The processor 21 of the wireless tag communication device 1 operates in a search mode after registering an operator who is a searcher based on information input by the input device 15. The processor 21 sets an RFID tag (target tag) to be searched for, as specified by the operator. After setting the target tag, the processor 21 starts a search process for the target tag in response to an instruction from the operator to start a search. When the processor 21 starts the search process for the target tag, it starts an estimation process for the position of the device itself (self-position) and a reading process for the target tag (ACT11, 12).

[0080] As a process of estimating the self-location, the processor 21 estimates the self-location based on a detection signal detected by the sensor 24 or 34. The processor 21 may estimate a relative position from a processing start position as the self-location, or may estimate an absolute position. As a process of estimating the self-location, the processor 21 repeatedly executes estimation of the self-location at a specific timing. The processor 21 stores in the memory 22 position information indicating the self-location obtained by estimating the self-location.

[0081] The processor 21 also performs a read process to read the target tag at a predetermined read cycle using the wireless tag communication unit 23. The wireless tag communication unit 23 transmits a response request (read command) and receives, as a received signal, a response wave output from an RFID tag in the read area in response to the response request. The processor 21 acquires the received signal including the tag information of the target tag as a result of reading the target tag.

[0082] When the target tag is read (ACT13, YES), the processor 21 stores (records) in the memory 22 the read result (read result of the target tag) including phase information of the signal received from the target tag and the read information including position information indicating the self-position (ACT14). For example, the processor 21 stores in the memory 22 the read information in which the read result of the target tag is associated with the position information indicating the self-position for each predetermined interval at which the tag position estimation process is performed. The predetermined interval at which the tag position estimation process is performed may be an interval (period or distance) different from the read cycle.

[0083] The processor 21 determines whether there are three or more pieces of read information to be used in the tag position estimation process at each predetermined interval when the tag position estimation process is executed (ACT15). For example, the above-mentioned tag position estimation process requires read results of reading a target tag at different self-positions. Therefore, the processor 21 determines whether three pieces of read information at different self-positions to be used in the tag position estimation process are present in the memory 22 at each predetermined interval. If there are not three pieces of read information to be used in the tag position estimation process (ACT15, NO), the processor 21 returns to the above ACT13.

[0084] When there are three pieces of read information to be used in the tag position estimation process (ACT15, Yes), the processor 21 determines whether or not an estimated tag position (estimated value of tag position) exists (ACT16). For example, the processor 21 stores the tag position estimated in the tag position estimation process (estimated tag position) in the memory 22. The processor 21 determines whether or not an estimated tag position exists in the memory 22.

[0085] If there is no estimated tag position (ACT16, No), the processor 21 proceeds to ACT19. In this case, the processor 21 does not know the tag position, and therefore the distance to the target tag is unknown. For this reason, the processor 21 sets the initial setting angle determination table as the angle determination table. For example, the processor 21 sets the distance to the target tag to the maximum (7.5 m or more in the example shown in FIG. 8) in the initial setting, and sets the angle determination table corresponding to the maximum distance.

[0086] If there is an estimated tag position (ACT16, Yes), the processor 21 calculates the distance from the most recent estimated tag position and the self-position to the target tag (ACT17). After calculating the distance to the target tag, the processor 21 selects an angle estimation table based on the calculated distance to the target tag (ACT18). For example, the processor 21 selects an angle estimation table that matches the calculated distance to the target tag from a plurality of angle estimation tables set for each distance of the target tag. The processor 21 sets the angle determination table selected based on the distance to the target tag as the angle determination table to be used in the tag position estimation process.

[0087] When the processor 21 sets the angle determination table according to the distance to the target tag, the processor 21 executes a tag position estimation process. As the tag position estimation process, the processor 21 estimates the direction of the target tag (ACT19), and estimates the position of the target tag from the direction of the target tag (ACT20).

[0088] For example, the processor 21 arranges three pieces of read information used in the tag position estimation process in chronological order to calculate Li, Lr, Li', and Lr' as shown in Fig. 4. After calculating the distance Li and the distance Lr, the processor 21 estimates the angle D corresponding to the ratio Li / Lr based on the set angle determination table. Furthermore, after calculating the distance Li' and the distance Lr', the processor 21 estimates the angle D' corresponding to the ratio Li' / Lr' based on the set angle determination table.

[0089] 4, the processor 21 estimates the direction from the first position (Pa) to the target tag (O) indicated by the angle D estimated from the ratio Li / Lr. The processor 21 also estimates the direction from the second position (Pb) to the target tag (O) indicated by the angle D' estimated from the ratio Li' / Lr'. The processor 21 estimates the position of the target tag (O) based on the direction from the first position (Pa) to the target tag (O) and the direction from the second position (Pb) to the target tag (O).

[0090] When the processor 21 estimates the position of the target tag, it notifies information indicating the estimated position of the target tag (ACT21). For example, the processor 21 displays information indicating the estimated position of the target tag on the display 14. This allows the operator to directly know the position where the target tag exists, rather than the direction in which the target tag is located.

[0091] Furthermore, in a state where the position of the target tag has been notified, processor 21 accepts an instruction to end the search (ACT22). For example, processor 21 accepts an instruction to end the search given by an operator using input device 15. If there is no instruction to end the search (ACT22, NO), processor 21 returns to ACT13 and repeats the above-mentioned process. Furthermore, if an instruction to end the search is given (ACT22, YES), processor 21 ends the search process for the target tag.

[0092] As described above, according to the first tag search process, the RFID tag communication device holds multiple angle determination tables corresponding to the distance to the target tag. The RFID tag communication device estimates the distance to the target tag and selects an angle determination table according to the distance to the target tag. When three or more pieces of read information are obtained at different positions, the RFID tag communication device estimates the direction of the target tag from the multiple positions using the angle determination table set according to the distance to the target tag. The RFID tag communication device estimates the position of the target tag based on the direction of the target tag from the multiple positions.

[0093] This allows the RFID tag communication device to estimate the direction of the target tag using a table corresponding to the distance to the target tag, and to perform tag position estimation processing based on the direction estimation result. In addition, since the direction estimation processing using the angle determination table is simple, high-speed tag position estimation processing can be realized.

[0094] Next, a second tag search process will be described in which the wireless tag communication device 1 according to the embodiment performs tag position estimation process using a calculation formula according to the distance to the target tag. In the second tag search process, the wireless tag communication device 1 executes a tag position estimation process including estimation of the tag direction using a formula indicating the relationship between the ratio Li / Lr and the angle D. The wireless tag communication device 1 stores a plurality of formulas set for each distance to the target tag in the memory 22. The wireless tag communication device 1 estimates the position of the target tag based on the direction of the target tag estimated using a formula selected according to the distance to the target tag.

[0095] 10 to 13 are diagrams showing examples of graphs and calculation formulas showing the relationship between the ratio Li / Lr and the angle D when the distance L to the target tag is specified. Fig. 10 shows a graph and a relational expression showing the relationship between the ratio Li / Lr and the angle D when the distance L to the target tag is 1 m. Fig. 11 shows a graph and a relational expression showing the relationship between the ratio Li / Lr and the angle D when the distance L to the target position is 3 m. Fig. 12 shows a graph and a relational expression showing the relationship between the ratio Li / Lr and the angle D when the distance L to the target tag is 5 m. Fig. 13 shows a graph and a relational expression showing the relationship between the ratio Li / Lr and the angle D when the distance L to the target tag is 7 m.

[0096] 10 to 13 are calculation formulas in which the ratio Li / Lr on the vertical axis is "y" and the angle D on the horizontal axis is "x." According to the relational expressions (calculation formulas) shown in Fig. 10 to 13, when the ratio Li / Lr is obtained, the processor 21 can calculate x as the angle D by substituting the ratio Li / Lr for y.

[0097] Fig. 14 is a diagram showing examples of calculation formulas set for each distance L to a target tag. The example shown in Fig. 14 shows calculation formulas when the distance L to a target tag is divided into the following ranges: 1.5 m or less, 1.5 to 2.5 (2±0.5) m, 2.5 to 3.5 (3±0.5) m, 3.5 to 4.5 (4±0.5) m, 4.5 to 5.5 (5±0.5) m, 5.5 to 6.5 (6±0.5) m, 6.5 to 7.5 (7±0.5) m, and 7.5 m or more.

[0098] In the example shown in Fig. 14, the calculation formula for distances of 1.5m or less is set using the relational expressions shown in Fig. 10. Similarly, in the example shown in Fig. 14, the calculation formula for distances L of 3±0.5m, 5±0.5m, and 7.5m or more is set using the relational expressions shown in Figs. 11, 12, and 13. Graphs and relational expressions can be obtained in the same way when the distance L to the tag position is 2m, 4m, and 6m. Therefore, the calculation formula for distances L of 2±0.5m, 4±0.5m, and 6±0.5m shown in Fig. 14 can be set using the relational expressions when distances L are m, 4m, and 6m.

[0099] The wireless tag communication device 1 estimates the distance to the tag position and selects a formula according to the distance to the tag position. The wireless tag communication device 1 estimates the angle D from the ratio Li / Lr using the selected formula. For example, when the distance L to the target tag is 1 m, the wireless tag communication device 1 estimates the angle D from the ratio Li / Lr using a formula of 1.5 m or less.

[0100] Next, a second tag search process including angle estimation using a calculation formula performed by the wireless tag communication device 1 according to the embodiment will be described. FIG. 15 is a flowchart for explaining an example of operation of a second tag search process including an angle estimation process using a calculation formula by the wireless tag communication device 1 according to the embodiment. The processor 21 of the RFID tag communication device 1 operates in a search mode after registering an operator who is a searcher based on information inputted by the input device 15. The processor 21 sets an RFID tag (target tag) to be searched for, designated by the operator. After setting the target tag, the processor 21 starts a search process for the target tag in response to an instruction from the operator to start a search.

[0101] When the processor 21 starts the search process for the target tag, it starts the process of estimating the position of its own device (its own position) and the process of reading the target tag (ACT31, 32). As a self-location estimation process, the processor 21 estimates the self-location based on a detection signal detected by the sensor 24 or 34. The processor 21 may estimate a relative position from a processing start position as the self-location, or may estimate an absolute position. The processor 21 stores in the memory 22 position information indicating the self-location obtained by estimating the self-location.

[0102] The processor 21 also performs a read process to read the target tag at a predetermined read cycle using the wireless tag communication unit 23. The wireless tag communication unit 23 transmits a response request (read command) and receives, as a received signal, a response wave output from an RFID tag in the read area in response to the response request. The processor 21 acquires the received signal including the tag information of the target tag as a result of reading the target tag.

[0103] When the target tag is read (ACT33, YES), the processor 21 stores (records) in the memory 22 the read result (read result of the target tag) including phase information of the signal received from the target tag and the read information including position information indicating the self-position (ACT34). For example, the processor 21 stores in the memory 22 the read information in which the read result of the target tag is associated with the position information indicating the self-position for each predetermined interval at which the tag position estimation process is performed. The predetermined interval at which the tag position estimation process is performed may be an interval (period or distance) different from the read period.

[0104] The processor 21 determines whether there are three or more pieces of read information to be used in the tag position estimation process at each predetermined interval when the tag position estimation process is performed (ACT35). For example, the above-mentioned tag position estimation process requires read results of reading a target tag at different self-positions. Therefore, the processor 21 determines whether there are three pieces of read information at different self-positions to be used in the tag position estimation process at each predetermined interval in the memory 22. If there are not three pieces of read information to be used in the tag position estimation process (ACT35, NO), the processor 21 returns to the above ACT13.

[0105] When there are three pieces of read information to be used in the tag position estimation process (ACT35, Yes), the processor 21 determines whether or not an estimated tag position (estimated value of tag position) exists (ACT36). The processor 21 stores the tag position estimated in the tag position estimation process (estimated tag position) in the memory 22. The processor 21 determines whether or not an estimated tag position exists in the memory 22.

[0106] If there is no estimated tag position (ACT36, No), the processor 21 proceeds to ACT39. In this case, the processor 21 does not know the tag position, and therefore the distance to the target tag is unknown. For this reason, the processor 21 sets the initial setting angle determination table as the angle determination table. For example, the processor 21 sets the distance to the target tag to the maximum (7.5 m or more in the example shown in FIG. 14) in the initial setting, and sets the angle determination table corresponding to the maximum distance.

[0107] If there is an estimated tag position (ACT36, Yes), the processor 21 calculates the distance from the most recent estimated tag position and the self-position to the target tag (ACT37). After calculating the distance to the target tag, the processor 21 selects an angle estimation table based on the calculated distance to the target tag (ACT38). For example, the processor 21 selects an angle estimation table that matches the calculated distance to the target tag from a plurality of angle estimation tables set for each distance of the target tag. The processor 21 sets the angle determination table selected based on the distance to the target tag as the angle determination table to be used in the tag position estimation process.

[0108] When the processor 21 sets the angle determination table according to the distance to the target tag, the processor 21 executes the tag position estimation process. As the tag position estimation process, the processor 21 estimates the direction of the target tag (ACT39), and estimates the position of the target tag from the direction of the target tag (ACT40).

[0109] For example, the processor 21 arranges three pieces of read information used in the tag position estimation process in chronological order to calculate Li, Lr, Li', and Lr' as shown in Fig. 4. After calculating the distance Li and the distance Lr, the processor 21 estimates the angle D corresponding to the ratio Li / Lr based on the set angle determination table. Furthermore, after calculating the distance Li' and the distance Lr', the processor 21 estimates the angle D' corresponding to the ratio Li' / Lr' based on the set angle determination table.

[0110] 4, the processor 21 estimates the direction from the first position (Pa) to the target tag (O) indicated by the angle D estimated from the ratio Li / Lr. The processor 21 also estimates the direction from the second position (Pb) to the target tag (O) indicated by the angle D' estimated from the ratio Li' / Lr'. The processor 21 estimates the position of the target tag (O) based on the direction from the first position (Pa) to the target tag (O) and the direction from the second position (Pb) to the target tag (O).

[0111] When the processor 21 estimates the position of the target tag, it notifies information indicating the estimated position of the target tag (ACT41). For example, the processor 21 displays information indicating the estimated position of the target tag on the display 14. This allows the operator to directly know the position where the target tag exists, rather than the direction in which the target tag is located.

[0112] Furthermore, in a state where the position of the target tag has been notified, the processor 21 accepts an instruction to end the search (ACT42). For example, the processor 21 accepts an instruction to end the search given by the operator using the input device 15. If there is no instruction to end the search (ACT42, NO), the processor 21 returns to ACT33 and repeats the above-mentioned process. Furthermore, if an instruction to end the search is given (ACT42, YES), the processor 21 ends the search process for the target tag.

[0113] As described above, according to the second tag search process, the RFID tag communication device holds multiple calculation formulas for estimating an angle according to the distance to the target tag. The RFID tag communication device estimates the distance to the target tag and selects a calculation formula to use for angle estimation according to the distance to the target tag. When three or more pieces of read information are obtained at different positions, the RFID tag communication device estimates the direction of the target tag from the multiple positions using a calculation formula selected according to the distance to the target tag. The RFID tag communication device estimates the position of the target tag based on the direction of the target tag from the multiple positions.

[0114] This allows the RFID tag communication device to estimate the direction of the target tag using a formula according to the distance to the target tag, and estimate the position of the target tag based on the direction estimation result. In addition, the direction estimation process using a formula can calculate an angle corresponding to a ratio with fine granularity using the formula, and the accuracy of estimating the direction can be improved.

[0115] Next, a modified example of the first tag search process and the second tag search process described above will be described. The angle estimation based on the angle judgment table of the first tag search process and the angle estimation based on the calculation formula of the second tag search process may be combined to perform the tag search process. For example, as a modified example, the angle estimation based on the angle judgment table and the angle estimation based on the calculation formula may be selected and performed.

[0116] In the first modified example, angle estimation using an angle judgment table or angle estimation using a formula is selected depending on the distance to the target tag. When the first modified example is implemented, for example, a threshold value (predetermined value) for selecting either angle estimation using the angle judgment table or angle estimation using a formula is stored in memory 22. Processor 21 of wireless tag communication device 1 selects angle estimation using the angle judgment table if the distance to the target tag is greater than the predetermined value. Also, processor 21 selects angle estimation using the formula if the distance to the target tag is within the predetermined value.

[0117] The wireless tag communication device according to the first modification can estimate the angle by an angle estimation using an easy-to-process angle determination table when the target tag is far away (when the distance to the target tag is a predetermined value or more). Also, the wireless tag communication device according to the first modification can estimate the angle by an angle estimation using a highly accurate calculation formula when the target tag is close (when the distance is within a predetermined value).

[0118] As a second modified example, angle estimation using an angle judgment table and angle estimation using a formula are selected depending on the ratio Li / Lr. When the second modified example is implemented, for example, a threshold value (predetermined value) for the ratio Li / Lr for selecting either angle estimation using the angle judgment table or angle estimation using a formula is stored in the memory 22. The processor 21 of the wireless tag communication device 1 selects angle estimation using the angle judgment table if the ratio Li / Lr is greater than the predetermined value. Also, the processor 21 selects angle estimation using the formula if the ratio Li / Lr is within the predetermined value.

[0119] The wireless tag communication device according to the second modification can estimate the angle by an angle determination table that is easy to process when the ratio Li / Lr is large, and can estimate the angle by an angle estimation using a highly accurate formula when the ratio Li / Lr is small.

[0120] In the above-mentioned embodiment, the case where the program executed by the processor is stored in advance in the memory in the device has been described. However, the program executed by the processor may be downloaded to the device from a network, or may be installed in the device from a storage medium. The storage medium may be any storage medium capable of storing a program such as a CD-ROM and readable by the device. Furthermore, the function obtained by pre-installation or downloading may be realized in cooperation with an OS (operating system) in the device.

[0121] Although some 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 implemented 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 in the scope and spirit of the invention, and are included in the scope of the invention and its equivalents described in the claims. [Explanation of symbols]

[0122] 1...wireless tag communication device, 10...reader device, 11...gripping portion, 12...holding portion, 13...information terminal device, 14...display, 15...input device, 21...processor, 22...memory, 23...wireless tag communication portion (communicator), 24...sensor (position detection sensor), 25...communication interface (interface), 26...camera (position detection sensor), 31...processor, 32...memory, 33...interface, 34...sensor (position detection sensor), 35...camera (position detection sensor).

Claims

1. A communication device for communicating with a target wireless tag; A position detection sensor that detects information indicating the self-position; a memory that stores a self-location determined from the information detected by the position detection sensor and a reading result obtained by reading the wireless tag by the communication device in association with each other; a processor that estimates a position of the wireless tag from a reading result obtained by reading the wireless tag at three different self-positions including a self-position that is an end point of the distance stored in the memory, using a processing method that is selected according to a distance between a self-position identified from information detected by the position detection sensor and an estimated position of the wireless tag; A wireless tag communication device having the above configuration.

2. the processor specifies a direction from a first self-location to the wireless tag and a direction from a second self-location to the wireless tag using a table that is selected according to the distance; The wireless tag communication device according to claim 1 .

3. the processor calculates a direction from a first self-location to the wireless tag and a direction from a second self-location to the wireless tag using a calculation formula selected according to the distance; The wireless tag communication device according to claim 1 .

4. the processor, if the distance is equal to or greater than a predetermined value, specifies a direction from a first self-location to the wireless tag and a direction from a second self-location to the wireless tag using a table selected according to the distance, and, if the distance is within a predetermined value, calculates a direction from the first self-location to the wireless tag and a direction from the second self-location to the wireless tag using a calculation formula selected according to the distance; The wireless tag communication device according to claim 1 .

5. the processor specifies a direction from a first position to the wireless tag and a direction from a second position to the wireless tag using a table selected according to the distance if the ratio between the distance approached to the wireless tag and the moving distance of the self-position is equal to or greater than a predetermined value, and calculates a direction from the first position to the wireless tag and a direction from the second position to the wireless tag using a formula selected according to the distance if the ratio is within a predetermined value; The wireless tag communication device according to claim 1 .

6. In the information processing device, Acquire information indicating the self-location where the communication device receives the signal from the target wireless tag, The self-location and the reading result based on the signal received by the communication device from the wireless tag are associated with each other and stored in a memory; using a processing method selected according to a distance between the self-location and the estimated location of the wireless tag, estimating the location of the wireless tag from a reading result obtained by reading the wireless tag at three different self-locations including the self-location that is an end point of the distance stored in the memory; A program to make it happen.

Images