COMMUNICATION APPARATUS, INFORMATION PROCESSING APPARATUS, AND POSITION INFORMATION MANAGEMENT METHOD

A communication apparatus detects a wireless device and calculates a relative position of the detected wireless device with respect to a reference wireless device to be a reference in identifying a position based on a movement amount of the communication apparatus from when the reference wireless device is detected by the communication apparatus. The communication apparatus associates the calculated relative position, identification information about the detected wireless device, and identification information about the reference wireless device.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to a technique for managing position information about a wireless device.

Background Art

In logistics, inventory taking, or animal management, a system of managing management target articles or animals using ultra-high frequency (UHF) passive radio frequency identification tags (hereinafter, referred to as RFID tags) as wireless devices are used. The RFID tags receive electric waves (electromagnetic waves) emitted from an antenna of an RFID reader and operate using power generated by the received electric waves (electromagnetic waves). This produces advantages that no batteries are needed and the RFID tags can be manufactured to be thin and at a low cost. However, since an RFID tag and the RFID reader can communicate only within short distances, there is a disadvantage that the RFID tags existing over a large area cannot be detected at one time.

Thus, a method for managing position information about management targets that exist over a wide area and to which RFID tags are attached has been discussed. Specifically, an RFID reader configured to detect the position information is carried, and the position information at the time of detection of an RFID tag is automatically associated with identification (ID) information about the RFID tag. Japanese Patent Application Laid-Open No. 2007-114003 discusses a technique for detecting position information about an RFID reader using the Global Positioning System (GPS).

CITATION LIST

Patent Literature

SUMMARY OF THE INVENTION

However, the method of detecting position information about the RFID reader using GPS is not suitable for indoor use. Furthermore, a GPS reception circuit needs to be provided, and thus there is an issue of an increased cost of the RFID reader.

Thus, the present invention is directed to a technique of managing position information about management target wireless devices existing over a large area with ease while preventing an increase in cost.

According to an aspect of the present invention, a communication apparatus includes a detection unit configured to detect a wireless device, a calculation unit configured to calculate a relative position of the detected wireless device with respect to a first wireless device to be a reference in identifying a position based on a movement amount of the communication apparatus from when the first wireless device is detected by the communication apparatus, and an association unit configured to associate the relative position calculated by the calculation unit, identification information about the detected wireless device, and identification information about the first wireless device.

According to another aspect of the present invention, an information processing apparatus includes a reception unit configured to receive, from a communication apparatus that detects a wireless device, identification information about the detected wireless device and information about a relative position of the detected wireless device with respect to a reference position, a calculation unit configured to calculate a relative position of the wireless device with respect to a first wireless device to be a reference in identifying a position based on the information received by the reception unit using information about a relative position of the first wireless device with respect to the reference position and the information about the relative position of the detected wireless device different from the first wireless device with respect to the reference position, and an association unit configured to associate the relative position calculated by the calculation unit, the identification information about the detected wireless device, and identification information about the first wireless device.

DESCRIPTION OF THE EMBODIMENTS

A method of managing position information about a management target wireless device according to various exemplary embodiments of the present invention will be described in detail below with reference to the drawings. In the management method according to an exemplary embodiment of the present invention, a communication apparatus configured to detect wireless devices is carried by a moving body such as a person or a machine to detect the wireless devices existing over a large area. The wireless devices are, for example, radio frequency identification (RFID) tags, and the communication apparatus is, for example, an RFID reader.

As illustrated inFIGS.2A,2B, and2C, there are methods in which, for example, a person (animal) wears an RFID reader100(FIG.2A) or the RFID reader100is attached to a machine such as a drone401or an automated guided vehicle501(FIGS.2B and2C). With the methods, the RFID reader100can be moved extensively and can detect RFID tags existing over a large area.

The RFID reader100has a function of feeding ultrahigh-frequency (UHF) electromagnetic waves to an RFID tag to cause an integrated circuit (IC) chip in the RFID tag to operate and to read identification (ID) information stored in a storage unit of the RFID tag. Further, the RFID reader100and the RFID tag can wirelessly communicate with each other over a distance of several meters.

In the present exemplary embodiment, as illustrated inFIG.15B, an RFID tag attached to a management target such as an article or an animal will be referred to as an article RFID tag40. The article RFID tag40is used to identify the management target to which the article RFID tag40is attached based on ID information stored in the article RFID tag40. Further, as illustrated inFIG.15A, an RFID tag for use as a reference in identifying a position of the article RFID tag40will be referred to as a position RFID tag30. The RFID reader100calculates a relative position of the article RFID tag40with respect to the position RFID tag30being a reference using a movement amount detection sensor104described below.

Information about the relative position of the article RFID tag40with respect to the position RFID tag30is displayed on a display unit14inFIG.3so that a user can locate the management target to which the article RFID tag is attached. Details of each process will be described below in the following exemplary embodiments.

While examples in which the RFID tags are used as detection target wireless devices and the RFID reader is used as a communication apparatus that detects the wireless devices are described in the exemplary embodiments of the present invention, the wireless devices and the communication apparatus are not limited to those in the examples. For example, other wireless communications such as short-range wireless communication, e.g., near field communication (NFC) or Bluetooth®, can be used instead of RFID. Alternatively, RFID using another frequency band can be used instead of UHF RFID.

First Exemplary Embodiment

FIG.1is a circuit block diagram illustrating the RFID reader100for use in a first exemplary embodiment. The RFID reader100is controlled by a calculation unit101including one or more processors such as a central processing unit (CPU). A radio frequency (RF) control unit110outputs UHF RF output from a transmission (TX) terminal based on the control by the calculation unit101. The RF output is amplified by a power amplifier111, and then a low-pass filter112cuts unnecessary frequency bands. The power of the RF output is variably set by the calculation unit101. A coupler113is used in detecting power by a RF power detection unit116.

A power detection result of the RF power detection unit116can be detected as an RF_Detect signal by the calculation unit101. A coupler114is used to separate RF output to an antenna unit115and RF input received from the antenna unit115. The antenna unit115is used to supply power to the RFID tags and to communicate with the RFID tags. A carrier wave cancellation unit117cancels a carrier wave component of the RF input based on a CARRIER_CANCEL signal, and a signal component of the RF input is received by a reception (RX) terminal of the RF control unit110, and ID information that is identification information about the RFID tag is detected.

The calculation unit101stores the ID information about the RFID tag that is detected by the RF control unit110in a storage unit102, performs necessary data processing, and then communicates with an information terminal10, which will be described below with reference toFIG.3, via a communication unit103. The storage unit102includes one or more memories such as a read-only memory (ROM) and a random access memory (RAM) and stores various types of data and programs to be processed by the calculation unit101. The communication unit103can communicate with the information terminal10via wired communication using Ethernet® or Universal Serial Bus (USB) or via wireless communication using a wireless local area network (wireless LAN) or a public wireless system.

The movement amount detection sensor104is a sensor that includes a three-axis acceleration sensor, a gyro sensor, and a geomagnetic sensor and detects a movement amount of the RFID reader100. The movement amount detection sensor104is used to calculate relative positions of the position RFID tag30to be a reference and the article RFID tag40. The movement amount detection sensor104can use any detection method by which a movement distance and a movement direction of the RFID reader are detectable. In exemplary embodiments of the present invention, information about a combination of a movement distance and a movement direction (two- or three-dimensional direction) is used as a movement amount.

While the RFID reader100automatically detects ID information about the RFID tags, the movement amount detection sensor104calculates relative positions of the RFID tags and associates the ID information about the plurality of RFID tags with information about the relative positions of the plurality of RFID tags. A power supply unit105is a circuit that includes a battery and a direct-current (DC)-DC converter and is used to supply a power source voltage to the RFID reader100.

FIG.3is a system diagram according to the present exemplary embodiment. The RFID tags are classified into the position RFID tag30(30ato30c) for use in detecting a reference position and the article RFID tag40(40ato40f) attached to a management target. Details of the RFID tags will be described below with reference toFIGS.15A and15B.

The RFID reader100associates ID information about the article RFID tag40, ID information about the position RFID tag30, information about the relative position of the article RFID tag40with respect to the position RFID tag30, and detection time of the article RFID tag40. Then, the pieces of information are transmitted to the information terminal10.

The information terminal10is an information terminal such as a smartphone or a personal computer (PC) and includes databases11and12and the display unit14. The database11stores data in which the ID information about the position RFID tag30and a position name are associated with each other and data in which the ID information about the article RFID tag40and an article name are associated with each other.

It is difficult for a user to recognize the ID information about the RFID tags directly, so that the ID information is converted into a name based on the database11and the converted name is displayed on the display unit14. Alternatively, the ID information about the RFID tags can be displayed directly on the display unit without using the database11.

The database12stores information received from the RFID reader100. Specifically, the database12stores data in which the ID information about the position RFID tag30, the ID information about the article RFID tag40, the relative position of the article RFID tag40with respect to the position RFID tag30, and the detection time of the article RFID tag40are associated with one another. The display unit14displays article position information based on a user instruction via an interface (not illustrated) of the information terminal10. A specific display method of the display unit14will be described below with reference toFIGS.5A,5B, and5C.

FIG.4is a flowchart illustrating a method of detecting position information about the article RFID tag by the RFID reader100according to the present exemplary embodiment. If a power source is changed to an ON state, the RFID reader100starts controlling the detection of article position information. The calculation unit101of the RFID reader100executes a program stored in the storage unit102to thereby implement each step of the flowchart inFIG.4.

In step S101, the RFID reader100sets the information about the relative position with respect to the reference position in the storage unit102to zero (x=0, y=0, z=0). The reference position is the position of the RFID reader100at the time of activation.

In step S102, the RFID reader100starts controlling calculation of an integral value of movement amounts based on detection results of the movement amount detection sensor104, updating of the information about the relative position with respect to the reference position, and storing of the information in the storage unit102. In step S103, the RFID reader100periodically causes the RF control unit110to operate to communicate with an RFID tag and starts controlling communication with the RFID tag.

In step S104, the RFID reader100determines whether ID information about the RFID tag is acquired from the RFID tag. In a case where the ID information about the RFID tag is acquired, the processing proceeds to step S105. On the other hand, in a case where the ID information about the RFID tag is not acquired, the processing of step S104is repeated.

In step S105, the RFID reader100determines whether the RFID tag is the position RFID tag30or the article RFID tag40based on the acquired ID information. As a method of discriminating the position RFID tag30from the article RFID tag40, for example, the ID information about the RFID tag can include an identifier for discriminating the position RFID tag30from the article RFID tag40. Further, the database11of the information terminal10can be referred to in the determination. In a case where the RFID tag is the article RFID tag, the processing proceeds to step S106. On the other hand, in a case where the RFID tag is the position RFID tag, the processing proceeds to step S108.

In step S106, the RFID reader100determines whether a reference position RFID tag is set. In a case where the reference position RFID tag is not set yet, e.g., in a case where it is immediately after activation of the RFID reader100, the processing proceeds to step S107. On the other hand, in a case where the reference position RFID tag is set, the processing proceeds to step S113.

In step S107, the RFID reader100stores data in which the ID information about the article RFID tag40, the detection time of the article RFID tag40, and the relative position of the article RFID tag40with respect to the reference position (initial position at the time of activation) are associated with one another in the storage unit102.

In step S108, the RFID reader100stores the ID information about the detected position RFID tag30as a reference position RFID tag in the storage unit102, and the processing proceeds to step S109. In step S109, the RFID reader100determines whether it is the first time to detect a position RFID tag after the activation of the RFID reader100. In a case where it is the first time to detect the position RFID tag, the processing proceeds to step S110. On the other hand, in a case where it is the second time or subsequent time, the processing proceeds to step S112.

In step S110, the RFID reader100performs the following processing on the data stored in the storage unit102in step S107. Specifically, relative positions of the position RFID tag30and the article RFID tag40are calculated based on the information about the relative position of the article RFID tag40with respect to the reference position and the information about the relative position of the position RFID tag30that is stored in the storage unit102in step S108with respect to the reference position. As used herein, the term reference position refers to the initial position at the time of activation of the RFID reader100(the position stored in step S101).

In step S111, the RFID reader100performs the following processing on the data stored in the storage unit102in step S107. Specifically, the RFID reader100associates the ID information about the article RFID tag40, the ID information about the position RFID tag30, the detection time of the article RFID tag40, and the information about the relative position of the article RFID tag40with respect to the position RFID tag30. Then, the RFID reader100transmits the information to the information terminal10. The communication unit103is used in the transmission.

In step S112, the RFID reader100sets the information about the relative position with respect to the reference position in the storage unit102to zero (x=0, y=0, z=0), and the processing returns to step S102. In step S113, the RFID reader100associates the ID information about the detected article RFID tag40, the ID information about the position RFID tag30, the detection time of the article RFID tag40, and the information about the relative position of the article RFID tag40with respect to the position RFID tag30. Then, the RFID reader100transmits the information to the information terminal10.

The RFID reader100repeats the foregoing control until a system end request is received (S114). With the process, the calculation unit101of the RFID reader100controls automatic detection of position information about the article RFID tag40attached to a management target and transmission of the detected position information to the information terminal10.

FIGS.5A,5B, and5Cillustrates an example of a display that is displayed on the display unit14of the information terminal10. In the display examples inFIGS.5A,5B, and5C, position information about management target articles is displayed based on the information in the databases11and12. In the display examples inFIGS.5A,5B, and5C, the display unit14displays the position RFID tag30as a double circle and the article RFID tag40as a single circle.

FIG.5Aillustrates an example of a display on the display unit14in a case where a user instructs the information terminal10to display information about ABC building 1stfloor north at time XX. In the database12, first, with respect to ID information40ato40c(articles a to c) about the article RFID tag40associated with ID information30a(ABC building 1stfloor north), data having the closest article detection time to the time XX is selected for each ID. Then, the information about the relative positions of the articles with respect to the position RFID tag is referred to so that the display unit14displays position information about the articles a to c based on the position of ABC building 1stfloor north as a reference. A user can locate the articles in actuality using the display information displayed on the display unit14and the disposed position RFID tag as a mark.

FIG.5Billustrates an example of a display on the display unit14in a case where a user issues an instruction to display ABC building 7th floor at the time XX. InFIG.5B, a display example in a case where articles d and e are each on a floor different from the 7thfloor of ABC building is illustrated. In a case where a distance between the relative positions of the articles d and e and a position RFID tag30con the 7thfloor of ABC building in a height direction is greater than a predetermined setting value, the articles d and e are detected as being on a floor different from the 7th floor of ABC building. The display unit14displays each article that is on a different floor as a dotted circle to indicate to a user that the articles d and e are not on the same floor as the position RFID tag30c. The display unit14displays a display indicating that the article d is on an upper floor of the 7thfloor of ABC building and the article e is on a lower floor of the 7thfloor of ABC building based on the information about the relative position with respect to the position RFID tag30c.

FIG.5Cillustrates an example of a display on the display unit14in a case where a user issues an instruction to display the article c at time YY. With respect to the position RFID tag30a(ABC building 1stfloor north) associated with the ID information40c(article c) in the database12and a position RFID tag30b(ABC building 1st floor east), data with the closest article detection time to the time YY is selected for each ID. Then, the information about the relative positions of the article with respect to the position RFID tag is referred to so that the display unit14displays the position of the article c with respect to the positions of the position RFID tag30aat ABC building 1stfloor north and the position RFID tag30bat ABC building 1stfloor east as a reference. In this display method, a user can locate the article c using the plurality of position RFID tags as marks. The position RFID tags30are displayed as follows. Specifically, the position RFID tag30aassociated with data of detection of the article c at the closest time to the time YY is illustrated as a solid double circle, and the position RFID tag30b, which is another position RFID tag, is illustrated as a dashed double circle. With this display method, a user can preferentially refer to the position information about the article detected at the closest time to the designated time YY.

As described above, the method of managing article position information according to the first exemplary embodiment uses the position RFID tag30as a reference in identifying a position for use in article management. Thus, the position RFID tag30does not have to be stored in association with quantitative position information. Thus, a user can introduce a position information detection system1with ease by simply attaching the article RFID tag40to a management target and installing the position RFID tag30.

When a user is to locate an article, even if quantitative coordinates indicating the position of an article are displayed on the display unit14, it is difficult for the user to intuitively locate the article. Displaying the position of the article with respect to the position of one position RFID tag30or the positions of the plurality of position RFID tags30as a reference makes it easier for the user to locate the article.

The position RFID tag30does not need connection of a power source cable. Thus, the position RFID tag30can be installed by a simple method, e.g., placing the position RFID tag30on a floor or attaching the position RFID tag30to a wall, so that the position information detection system1can be introduced with ease not only for indoor use but also for outdoor use.

The position RFID tag30does not have to be situated at a fixed position. For example, the position RFID tag30can be installed in a truck bed to detect position information about an article in the moving truck bed.

As described above, the system of managing article position information according to the present exemplary embodiment can be easily introduced both inside and outside with at low cost and can manage position information about management targets to which the RFID tags are attached existing over a large area.

Second Exemplary Embodiment

FIG.9is a system diagram according to a second exemplary embodiment. A system according to the present exemplary embodiment is different from the first exemplary embodiment in that a server20, instead of the RFID reader100, processes data necessary for position detection and that the database12also manages the position RFID detection time in association. Each configuration similar to that in the first exemplary embodiment is given the same reference numeral, and a redundant description thereof is omitted.

In a position detection system2inFIG.9, the plurality of RFID readers100(100a,100b, . . . ) is connected to the server20. Each RFID reader100transmits data to the server20in association with ID information about the RFID tags (the article RFID tag40and the position RFID tag30), relative positions of the RFID tags with respect to a reference position described below, and the detection time of each of the RFID tags. A time display inFIG.9indicates that the detection time proceeds in the order of10,11,12,20,21, and31.

FIG.18illustrates a hardware configuration of the server20according to the present exemplary embodiment. A storage unit1801includes one or more memories, such as one or both of a ROM and a RAM, and stores programs for executing various operations described below and databases described below. Besides the memories such as the ROM and RAM, a storage medium such as a flexible disk, a hard disk, an optical disk, a magneto-optical disk, a compact disk (CD) ROM, a CD recordable (CD-R), a magnetic tape, a non-volatile memory card, or a digital versatile disk (DVD) can be used as the storage unit1801.

A control unit1802includes a calculation unit23illustrated inFIG.9and includes, for example, one or more processors such as a CPU and a micro processing unit (MPU), an application-specific integrated circuit (ASIC), a digital signal processor (DSP), and a field-programmable gate array (FPGA). CPU is the abbreviation for Central Processing Unit, and MPU is the abbreviation for Micro Processing Unit. The control unit1802executes a program stored in the storage unit1801to thereby control the entire apparatus.

An input unit1803receives various operations from a user. An output unit1804outputs various types of output to a user. The output of the output unit1804includes at least one of a display on a screen, audio output via a speaker, and vibration output. Alternatively, the input unit1803and the output unit1804can be implemented by a single module such as a touch panel. A communication unit1805can perform wired or wireless communication, and the server20can communicate with the RFID reader using the communication unit1805.

In the system diagram inFIG.9, databases to be stored in the storage unit1801of the server20are illustrated. The server20discriminates the position RFID tag30from the article RFID tag40, as described below with reference toFIG.11. In a case where the server20receives data on the position RFID tag30from the RFID reader100, the server20stores the data in a database21a, whereas in a case where the server20receives data on the article RFID tag40, the server20stores the data in a database21b. The databases21aand21bstore ID information about the RFID reader100to identify the RFID reader by which the data is received. The databases21aand21bare databases for temporary storage for use in data processing and generating of the database12by the server20.

The database11of the server20stores the time of installation of the position RFID tag in addition to the position name of the position RFID tag30. Here, data on a case where the position RFID tag30of the ID information30ais installed at ABC building 1stfloor north at time10and is then moved to and installed at ABC building 2nd floor at time20is illustrated. The position RFID tag30of ID information30bindicates that the position RFID tag30is installed at ABC building 1stfloor east at the time10.

The database12stores the ID information about the position RFID tag30, the ID information about the article RFID tag40, the relative position of the article RFID tag40with respect to the position RFID tag30, the detection time of the article RFID tag40, and the detection time of the position RFID tag30in association.

Use of an installation time of the position RFID tag30in the database11and an installation time of the position RFID tag30in the database12makes it possible to process data as suitable for a case where the position RFID tag30is moved, as described below with reference toFIGS.12A,12B, and12C. The RFID reader and the server20can communicate via a network such as the Internet or an intranet. The server20as an information processing apparatus can include a single apparatus or a plurality of apparatuses. Further, the server20can include a plurality of apparatuses cooperating via a network such as the cloud. Further, the server20and the information terminal10can be integrated.

FIG.10is a flowchart illustrating a process that is executed by the RFID reader100according to the present exemplary embodiment. The calculation unit101of the RFID reader100executes a program stored in the storage unit102to thereby implement the steps in the flowchart inFIG.10.

In step S221, the RFID reader100transmits information associated with RFID reader ID information, RFID tag ID information, RFID tag detection time, and the relative positions of the RFID tag with respect to the reference position to the server20.

The RFID reader100according to the present exemplary embodiment performs only the minimum data processing and transmits the data to the server20, and the server20processes the data used for position detection. Thus, in the system2according to the present exemplary embodiment, the data processing to be performed by the RFID reader100is reduced, so that the calculation unit101that has low calculation capacity can be used, and the necessary data capacity for the storage unit102is reduced.

FIG.11is a flowchart illustrating a process that is executed by the server20according to the present exemplary embodiment. The control unit1802of the server20executes a program stored in the storage unit1801to thereby implement the steps in the flowchart inFIG.11.

In step S201, the server20waits until data is transmitted from the RFID reader100, and the processing proceeds to step S202. In step S202, the server20determines whether the RFID reader100is reactivated by turning on and off the power source. In the case where the RFID reader100is reactivated, the reference position at the time of activation that is to be used as a reference is changed, so that information about the relative position in the RFID tag detection result before the reactivation and the RFID tag detection result after the reactivation can no longer be detected. Thus, in a case where the RFID reader100is reactivated, the processing proceeds to steps S208to S210, and the data processing on the RFID tag detected before the reactivation is completed. Thereafter, the data in the databases that has been analyzed is erased, and the processing returns to step S201. The databases21aand21berase old data that has been analyzed so that the amount of data to be stored in the server20is reduced.

In the present exemplary embodiment, a case where the RFID readers100aand100bare reactivated between time12and the time20and between time21and time31inFIG.9will be described below. For a purpose of description, the old data to be erased is also displayed in the databases21aand21binFIG.9.

In step S203, the server20receives the data in which the RFID reader ID information, the RFID tag ID information, the RFID tag detection time, and the relative position of the RFID tag with respect to the reference position are associated with one another. In step S204, the server20determines whether the RFID tag is the position RFID tag30or the article RFID tag40based on the RFID tag ID information. In a case where the RFID tag is the position RFID tag30, the processing proceeds to step S205. On the other hand, in a case where the RFID tag is the article RFID tag40, the processing proceeds to step S206.

In step S205, the server20stores the data received in step S203in the database21aas data on the position RFID tag30. In step S206, the server20stores the data received in step S203in the database21bas data on the article RFID tag40. In step S207, the server20checks whether a request to analyze the data in the databases21aand21bis received. The server20performs data analysis, for example, in a case where a predetermined number of pieces of data or more are accumulated in the databases21aand21b, at regular timings, or based on a user instruction.

In step S208, the server20associates the position RFID tag30and the article RFID tag40from the databases21aand21bthat are detected at the closest time among the data detected by the same RFID reader100. Thereafter, the processing proceeds to step S208.

In a method of associating the data in the databases21aand21baccording to a modified example, the position RFID tag30and the article RFID tag40that are detected at the closest relative positions by the same RFID reader100are stored in association with each other. Further, in a case where the database12has a large storage capacity, combinations of data to associate the position RFID tag30and the article RFID tag40can be increased. For example, the article RFID tag40can be stored in the database12in association with both the position RFID tag30detected at the closest time and the position RFID tag30detected at the closest relative position.

Associated data120in the parentheses in the database12inFIG.9is an example of data in which the position RFID tag30and the article RFID tag40that are detected not at the closest time are associated with each other.

In step S209, the server20calculates the relative position of the article RFID tag40with respect to the position RFID tag30that has been associated in step S208based on the relative position of the position RFID tag30with respect to the reference position and the relative position of the article RFID tag40with respect to the reference position.

As described above, the data transmitted from the RFID reader100to the server20is associated with the information about the relative positions of the article RFID tag40and the position RFID tag30based on a common reference position (the common reference position in the present exemplary embodiment is the initial position at the time of activation of the RFID reader100). Thus, the relative position of the article RFID tag40with respect to the position RFID tag30can be calculated by data processing by the server20.

The common reference position does not have to be the initial position at the time of activation of the RFID reader100and, for example, a position at which an RFID tag is detected for the first time after the RFID reader100is activated can be used as the reference position. The method illustrated inFIG.11is a mere example of a method of transmitting information about relative positions of a plurality of RFID tags detected by the RFID reader100, and any other methods can be used.

The RFID reader100includes at least a unit that detects the RFID tag ID information and the information about a relative position of an RFID tag with respect to the reference position. The server20can calculate the relative position of the position RFID tag30with respect to the article RFID tag40based on the ID information and the information about the relative positions of the plurality of RFID tags that are transmitted from the RFID reader100.

In step S210, the server20associates the ID information about the article RFID tag40, the ID information about the position RFID tag30, the detection time of the article RFID tag40, the detection time of the position RFID tag30, and the relative position of the article RFID tag40with respect to the position RFID tag30. Then, the information is stored in the database12.

The foregoing process is repeated until a system end request is received (S114).

FIGS.12A,12B, and12Ceach illustrate an example of a display that is displayed on the display unit14of the information terminal10according to the present exemplary embodiment. In the display examples illustrated inFIGS.12A,12B, and12C, position information about management target articles is displayed based on the information in the databases11and12.

The information terminal10transmits information such as position name, article name, and time to the server20based on a user instruction via an interface (not illustrated) of the information terminal10. The server20having received the information selects data necessary for the display on the display unit14from the database12and transmits the selected data to the information terminal10. The information terminal10displays article position information on the display unit14based on the data received from the server20.

FIG.12Aillustrates a display example in which position information about the article RFID tag40with respect to ABC building 1stfloor north (ID information30aabout the position RFID tag30) at time11as a reference is displayed. From the database11inFIG.9it is understood that the position RFID tag30is installed at ABC building 1stfloor north during the period from the time10to the time20. The server20selects data with the ID information about the position RFID tag30that matches30aand with the detection time of the article RFID tag closest to the time11during the period from the time10to the time20. The server20transmits the article name of the article RFID tag40of the selected data and the information about the relative position of the article RFID tag40with respect to the position RFID tag30ain association, so that the information terminal10can display the article position information illustrated inFIG.12Aon the display unit14.

Meanwhile, in data processing by the server20, the information about the articles a and b is associated with ABC building 1stfloor north based on a detection result of the RFID reader100a. The information about the article c is associated with ABC building 1stfloor north based on a detection result of the RFID reader100b. As described above, information detected by the plurality of RFID readers100is combined by the server20to reduce detection omissions of the article RFID tag40.

FIG.12Billustrates position information about the article RFID tag40with respect to ABC building 2ndfloor (ID information30aabout the position RFID tag30) at time21as a reference. From the database11inFIG.9it is understood that the position RFID tag30of the ID information30ais at ABC building 2ndfloor at the time20. Thus, the display inFIG.12Buses the position RFID tag30detected at the time20or after and the detection result of the article RFID tag40.

As described above, in a case where the position RFID tag30is moved, a user only needs to register a new position name and installation time in the database11after the position RFID tag30is moved. Thus, the user can move a use site of the position detection system2by a simple operation.

Further, the database12stores the detection time of the position RFID tag30in addition to the detection time of the article RFID tag40. Thus, even in a case where a user installs the position RFID tag30at a new position and, after a while, the user registers the name of the new position of the position RFID tag30and installation time thereof in the database11, article position information of past data in the database12can be retrospectively displayed. In the case where the position RFID tag30is moved, a method in which the detection time of the position RFID tag30is also stored in the database12is effective.

FIG.12Cillustrates position information about the article RFID tag40with respect to ABC building 1stfloor east (ID information30babout the position RFID tag30) at time31as a reference. As specified in the database11inFIG.9, the position RFID tag30of the ID information30bis installed at ABC building 1stfloor east at the time10. Thus, the display inFIG.12Cuses the position RFID tag30detected at the time10or after and the detection result of the article RFID tag40among the data on the article RFID tag40associated with the position RFID tag30of the ID information30b.

An advantage of the control method according to the present exemplary embodiment in a case where a user A of the RFID reader100ainstalls the position RFID tag30aand a user B of the RFID reader100binstalls the position RFID tag30bwill be described below. Since the user B has installed the position RFID tag30bat ABC building 1stfloor east by the time31, the user A can detect the position RFID tag30band the relative positions of the articles b and c at the time31with use of the RFID reader100a. Thus, it is understood that as more users use the position detection system2and install the position RFID tag30, it becomes easier to detect the position of the article RFID tag40.

In the position detection system2according to a modified example, the information terminal10is not used, the RFID reader100includes the display unit14, and the server20transmits data to the RFID reader100to display the data on the display unit14of the RFID reader100. Further, instead of the RFID reader100and the server20communicating directly, the RFID reader100and the information terminal10can be connected so that the RFID reader100and the server20communicate via the information terminal10. Further, instead of using the server20, the information terminal10can perform the data processing of the server20according to the present exemplary embodiment.

As described above, the RFID reader100according to the present exemplary embodiment includes a unit that detects the ID information about the RFID tag and detects the information about the relative position of the RFID tag with respect to the reference position. The server20can calculate the relative position of an article RFID tag with respect to the position RFID tag based on the information transmitted from the RFID reader100.

Third Exemplary Embodiment

FIG.13is a system diagram according to a third exemplary embodiment. The system according to the present exemplary embodiment uses an RFID reader200in which the RFID reader100according to the first exemplary embodiment and the information terminal10are integrated. The present exemplary embodiment is different from the first exemplary embodiment in that the database12stores the ID information about the article RFID tag40in association with only the information about the relative position with respect to the reference position. Each configuration similar to that in the first exemplary embodiment is given the same reference numeral, and a redundant description thereof is omitted.

The RFID reader200inFIG.13includes the functions of the display unit14and the databases11and12in addition to the function of the RFID reader100according to the first exemplary embodiment. Instead, the communication unit103is not included.

The position detection system3according to the present exemplary embodiment includes only one position RFID tag30, and it is unnecessary to store the ID information about the position RFID tag30in association with the ID information about the article RFID tag40and the relative position information in the database12. Further, it is also unnecessary to store the position RFID tag30in the database11in association with the position name. In order to discriminate between the position RFID tag30and the article RFID tag40, only the ID information about the position RFID tag30is stored in the database11.

Further, the position detection system3can display only the newest position information detection result on the display unit14, and it is unnecessary to store the detection time of the article RFID tag40in association in the database12. The detection result of the newest article RFID tag40is updated and stored for each ID.

FIG.14is a flowchart illustrating a process that is executed by the RFID reader200according to the present exemplary embodiment. The flowchart is different from the flowchart inFIG.4according to the first exemplary embodiment in that after a position RFID tag is detected in step S105, updating of article RFID tag data is started. Another difference is that only the ID information about the article RFID tag40and the information about the relative position of the article RFID tag40with respect to the position RFID tag30are stored in step S314. The calculation unit101of the RFID reader200executes the steps in the flowchart inFIG.14as inFIG.4.

Under the control according to the present exemplary embodiment, the RFID reader200does not update the RFID tag data until the position RFID tag30is detected in step S105. Thus, in step S301, the display unit14displays a display that prompts a user to come close to the position RFID tag until the position RFID tag30is detected for the first time.

Further, in a case where the position RFID tag30is not detected for a predetermined period from the start of the control by the RFID reader100, control is performed to prompt a user to detect the position RFID tag30using a display on the display unit14or a buzzer. This can be performed also in the cases of the first and second exemplary embodiments.

In step S314, the RFID reader200updates the ID information about the article RFID tag40and the information about the relative position of the article RFID tag40with respect to the position RFID tag30ain the database12. The display unit14displays the relative position of the article RFID tag with respect to the position RFID tag30a.

The foregoing process is repeated until a system end request is received (S114).

As described above, in the position detection system3according to the present exemplary embodiment, the ID information about the position RFID tag30and the detection time of the article RFID tag40do not have to be stored, so that the necessary data capacity of the database12can be further reduced. Thus, the system is applicable even in a case where the storage unit102of the RFID reader200has a small data capacity. Further, since it is not necessary to communicate with the information terminal10or the server20, the communication unit103is not needed, so that the cost of the RFID reader200can be reduced.

Only the ID information about the article RFID tag40and the information about the relative position of the article RFID tag40with respect to the position RFID tag30are the data to be managed in the database12according to the present exemplary embodiment. Even in this case, position information about management targets to which RFID tags are attached and that can be used both indoor and outdoor with ease at a low cost and are existing over a large area can be managed.

[Description of Position RFID Tag and Article RFID Tag]

FIGS.15A and15Bare diagrams illustrating RFID tags that are examples of the position RFID tag30and the article RFID tag40that can be used in the first to third exemplary embodiments.

The position RFID tag30illustrated inFIG.15Ais used as a reference position in managing position information about an article to which the article RFID tag40is attached. A holding member32is an exterior package used to hold the position RFID tag30.

As illustrated inFIG.15B, the article RFID tag40is a RFID tag attached to an article.

Meanwhile, the position RFID tag30and the article RFID tag40are RFID tags that can communicate with the RF control unit110of the RFID reader100and operate based on the same principles. Thus, in the position information management methods according to the first to third exemplary embodiments, it is unnecessary to separately provide a detection circuit for article detection and a detection circuit for position detection, so that advantages such as reduced cost, reduced size, and reduced power consumption of the RFID reader100can be obtained.

[Method of Increasing Article Position Detection Accuracy]

FIGS.6and7are flowcharts each illustrating a process of control of a method of further increasing the accuracy of position information about the article RFID tag40. The processes are executed as needed when the RFID reader detects the position RFID tag in the first to third exemplary embodiments. The calculation unit of the RFID reader executes a program stored in the storage unit to thereby execute the steps in the flowcharts inFIGS.6and7.

The control inFIG.6is started if the RFID reader100detects the position RFID tag30.

In step S401, the RFID reader100stores the detected ID information about the position RFID tag30in the storage unit102. In step S402, the RFID reader100decreases a level of RF output (Tx signal) of the RF control unit110of the RFID reader100. In step S403, the RFID reader100determines whether communication with the position RFID tag30stored in step S401is successful again. In a case where the communication is successful, the processing proceeds to step S402, and the RF output of the RFID reader is further reduced, and the processing is repeated until the communication is no longer successful in step S403. On the other hand, in a case where the communication is not successful, the processing proceeds to step S404.

In step S404, the RFID reader100stores the lowest RF output at which the communication with the position RFID tag30is successful in association with the ID information about the position RFID tag30. In step S405, the RFID reader100determines whether the RF output is the lowest RF output value in a predetermined period in a history of successful communication with the position RFID tag30of the same ID information. In step S405, in a case where the RF output is the lowest RF output value, the processing proceeds to step S108. In step S108, the ID information about the position RFID tag30that is detected is stored in the storage unit102, and the processing proceeds to step S112. In step S112, the relative position is set to zero. On the other hand, in step S405, in a case where the RF output is not the lowest RF output value, the position RFID tag detection result is voided, and the relative position is not set to zero.

In the control flowchart inFIG.6, in a case where the RFID reader100successfully detects the position RFID tag30at low RF output, it is determined that the position RFID tag30and the RFID reader100are near each other. Then, at this timing, the relative position is set to zero so that data upon successful detection of the position RFID tag30at the low RF output is associated with the detected data on the article RFID tag40.

Similarly, the control inFIG.7is started if the RFID reader100detects the position RFID tag30.

In step S504, the RFID reader100stores the intensity of the RF input (Rx signal) received by the RF control unit110of the RFID reader100in the storage unit102. In step S505, the RFID reader100determines whether the RF input is the highest RF input value in a predetermined period in a history of successful communication with the position RFID tag30of the same ID information. In step S505, in a case where the RF input is the highest RF input value, the processing proceeds to step S108. In step S108, the ID information about the position RFID tag30that is detected is stored in the storage unit102, and the processing proceeds to step S112. In step S112, the relative position is set to zero. On the other hand, in step S505, in a case where the RF input is not the highest RF input value, the position RFID tag detection results are voided, and the relative position is not set to zero.

In the control flowchart inFIG.7, in a case where the RFID reader100successfully detects the position RFID tag30at high RF input, it is determined that the position RFID tag30and the RFID reader100are near each other. Then, at this timing, the relative position is reset so that data on successful detection of the position RFID tag30at the high RF input is associated with the detected data on the article RFID tag40.

In the article position management system according to each of the exemplary embodiments of the present invention, the position RFID tag30is used as the reference position. Thus, performing the control methods illustrated inFIGS.6and7particularly on the position RFID tag30increases accuracy of position information to be managed.

Further, performing control similar to those inFIGS.6and7on the article RFID tag40can increase the accuracy of position information to be managed.

In a case where the server20performs data processing as in the second exemplary embodiment, data on the intensity of the RF input or the intensity of RF output of the RFID reader100is stored in association with the databases21aand21bof the server20. This enables the server20to perform control similar to those inFIGS.6and7. The methods of increasing the accuracy of position information that are illustrated inFIGS.6and7are also applicable to the cases of the second exemplary embodiment.

FIG.8illustrates a method of using a charging apparatus300of the RFID reader100as the position RFID tag30by including the function of the position RFID tag30in the charging apparatus300. A connector301is used to connect the charging apparatus300with the RFID reader100.

Use of the charging apparatus300makes it possible to detect the position RFID tag30in short range at the time of charging the RFID reader100. In particular, by combining with the control inFIGS.6and7, the accuracy of position information about the RFID reader100is increased.

[Control of Radiation Directivity of Antenna]

FIGS.16A,16B,16C, and16Dillustrate the antenna unit115with a radiation directivity control function that can be used in the first to third exemplary embodiments. Substrates1101and1102are overlaid along a Z-axis, which is a thickness direction of the substrates1101and1102, in this order in a −Z direction.

FIG.16Aillustrates a front surface of the substrate1101. Four antenna elements1103are arranged in such a manner that extension directions of the antenna elements1103are each changed by 90 degrees along X- and Y-axes so that open ends do not overlap, and a power-feed end, which is an end portion on the opposite side of the open end, is connected to a via1104. The extension directions of the open ends can be the opposite directions, or an element shape can be a meander line shape.

FIG.16Billustrates a back surface of the substrate1101. Four vias1104are through the substrate1101and are connected to four pads1105.

FIG.16Cillustrates a front surface of the substrate1102. Four pads1106are connected to a ground1107and respectively to four RF lines1108. The pads1105and1106are each in surface contact with a metallic spacer that is a conductive portion (not illustrated) to become conductive.

The four RF lines1108pass through respective four RF switches1109(1109ato1109d) and a shared RF line1110, and are connected to a transmission/reception unit1111(coupler114).

One end of each of the RF switches1109is connected to each of the RF lines1108, and another end thereof is connected to the RF line1110, and the RF switch1109controls whether to short-circuit or open. Thus, in a case where the RF switch1109is in a short-circuited state, RF signals can pass through between the transmission/reception unit1111and the antenna element1103, whereas in a case where the RF switch1109is in an open state, RF signals cannot pass through between the transmission/reception unit1111and the antenna element1103.

FIG.16Dillustrates a back surface of the substrate1102. A ground1112is disposed over an entire surface except for regions that overlap the pads1106and is electrically connected to the ground1107through a plurality of vias (not illustrated) through the substrate1102. The line width and thickness of the RF lines1108and1110are determined based on a layer structure and permittivity of the substrate1102to obtain about 50 ohm at RF signal frequencies.

The four pads1106are respectively defined as A, B, C, and D in this order in a counterclockwise direction from the top right in the drawing, and total electric lengths of the RF lines connecting A, B, C, D and the transmission/reception unit1111are respectively denoted by a, b, c, and d. At this time, the four RF lines1108are arranged in a meander line shape to satisfy the relationships b=a+λ/4, c=b+λ/4, and d=c+λ/4 and to not overlap the ground1107. The four RF lines1108are each to have a phase difference of λ/4, i.e., about 90 degrees, and rotation directions and implementation methods to provide the phase differences can be any directions and methods, and a phase shifter can be used instead of line lengths.

The RF signals that are transmitted and received by the antenna unit115are circularly polarized waves in a case where the RF signals are combined waves of the four antenna elements1103, whereas the RF signals are linearly polarized waves in a case where the RF signals are combined waves of a combination of the two facing antenna elements1103.

FIGS.17A,17B, and17Cillustrate radiation characteristics of an antenna that resonates at 920 MHz in the present exemplary embodiment. At this time, the substrates1101and1102each have a substrate thickness of 1 mm and a relative permittivity of 4.3, and a distance between the substrates1101and1102is 7 mm, and an element length of an inverted-F antenna is about 214. Further, the RF lines each have a line width of 1.6 mm and a line thickness of 35 um.

FIG.17Aillustrates radiation characteristics in a case where all of the RF switches1109ato1109dare short-circuited, and RF signals of circularly polarized waves with the main directivity in a +Z direction are emitted.

FIG.17Billustrates radiation characteristics in a case where the RF switches1109aand1109care short-circuited and the RF switches1109band1109dare opened, and RF signals of linearly polarized waves are emitted in +X and −X directions.

FIG.17Cillustrates radiation characteristics in a case where the RF switches1109band1109dare short-circuited and the RF switches1109aand1109care opened, and RF signals of linearly polarized waves are emitted in +Y and −Y directions.

With the techniques described above, RFID tags that are situated in X-axis and Y-axis directions and cannot be read by RF signals of circularly polarized waves emitted in the +Z direction alone become readable by changing the directivity. Furthermore, position information about articles to which the RFID tags are attached existing over a large area become detectable. The RFID reader100detects the RFID tags while changing the radiation characteristics of the antenna unit115in a plurality of directions, and the antenna unit115is suitable for use in the first to third exemplary embodiments.

Other Embodiments

The first to third exemplary embodiments described above can be implemented in combination as needed. For example, the RFID reader including the display unit according to the third exemplary embodiment does not necessarily have to display position information about management target articles on the display unit of the RFID reader and can transmit the information to a server or an information terminal. Alternatively, whether to display the information on the RFID reader or to transmit the information to the server or the information terminal can be selected by a user operation.

The present invention is not to be limited to the above described exemplary embodiments and can be altered or modified in various ways without departing from the spirit and the scope of the present invention. Therefore, the following claims are appended to make the scope of the present invention public.

Other Embodiments