Radio tag communication device and program

Abstract

To provide a wireless tag communication device that can efficiently search for a wireless tag to be searched, and a program.SOLUTION: A wireless tag communication device includes an antenna configured to transmit a carrier wave and receive a response wave output from a wireless tag with respect to the carrier wave and to specify a position of the wireless tag to be searched based on a radio wave intensity of the response wave received by the antenna. The device includes: a radio wave controller configured to switch the carrier wave between a first and second carrier wave to be transmitted in a first and second polarization direction respectively; and a comparator configured to compare a first and second radio wave intensity of a first and second response wave respectively output from the wireless tag with respect to the first and second carrier waves respectively. The radio wave controller switches the carrier wave between the first carrier wave and the second carrier wave based on a comparison result of the comparator.SELECTED DRAWING: Figure 8

Description

[Technical Field]

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

[0002] In recent years, wireless tag communication devices that use RFID (Radio Frequency Identification) technology to locate items have come into use. Known wireless tag communication devices of this type are comprised of a handheld RFID reader carried by a user, and communicate with an RFID tag (hereinafter also referred to as a wireless tag) attached to an item to recognize the location of the item and display the recognized location (for example, Patent Document 1).

[0003] The RFID tag communication device is used in a warehouse or the like that stores a large number of products, and by inputting the identification information of the RFID tag attached to the product to be searched for (hereinafter also referred to as the "RFID tag to be searched for"), it is possible to search for the product to which the RFID tag is attached from among the large number of products. The RFID tag communication device detects changes in the radio wave intensity received from the RFID tag that occur when a user moves around while carrying the RFID tag communication device, and thereby recognizes the location of the product to be searched for.

[0004] The radio tag communication device is configured to output radio waves by switching between multiple polarization directions so that communication can be performed regardless of the relationship between the orientation of the antenna face of the radio tag communication device held by the user and the orientation of the radio tag being searched for.

[0005] However, in conventional RFID tag communication devices, the polarization direction is still switched even after the position of the RFID tag to be searched for has been narrowed down and the orientation of the antenna face of the RFID tag communication device and the orientation of the RFID tag to be searched for have become constant, which has resulted in the problem that the search for items is not necessarily efficient. This is because the RFID tag communication device constantly switches the polarization direction to output the carrier wave, and as a result, also outputs radio waves in a polarization direction that does not contribute to communication with the RFID tag to be searched for. Summary of the Invention [Problem to be solved by the invention]

[0006] The problem to be solved by the present invention is to provide a radio tag communication device and a program that can efficiently search for a radio tag to be searched for. [Means for solving the problem]

[0007] The RFID tag communication device of the embodiment has an antenna that transmits a carrier wave and receives a response wave output from the RFID tag in response to the carrier wave, and is capable of identifying the position of the RFID tag being searched for based on the radio wave intensity of the response wave received by the antenna, and switches the carrier wave between a first carrier wave transmitted in a first polarization direction and a second carrier wave transmitted in a second polarization direction. and a dual polarization mode in which the first carrier wave and the second carrier wave are alternately transmitted, and a single polarization mode in which either the first carrier wave or the second carrier wave is transmitted. a radio wave control unit; and a comparison unit that compares the radio wave intensity of a first response wave output by the wireless tag in response to the first carrier wave with the radio wave intensity of a second response wave output by the wireless tag in response to the second carrier wave, wherein the radio wave control unit: If the antenna fails to receive the reply wave a preset number of times in succession, the output value of the carrier wave is increased by one step and the antenna is set to the dual polarization mode, and if the antenna succeeds in receiving the reply wave a preset number of times in succession, the output value of the carrier wave is decreased by one step and the antenna is set to the single polarization mode based on the comparison result of the comparator. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram for explaining a usage mode of a radio tag communication device according to an embodiment. [Figure 2] FIG. 2 is a diagram showing the relationship between the RFID tag communication device of the embodiment and the polarization direction of the carrier wave. [Figure 3] FIG. 3 is a diagram showing an example of the relationship between the first polarization direction and the antenna of the wireless tag in the embodiment. [Figure 4] FIG. 4 is a diagram showing an example of the relationship between the second polarization direction and the antenna of the wireless tag in the embodiment. [Figure 5] FIG. 5 is a block diagram showing a hardware configuration of the radio tag communication device according to the embodiment. [Figure 6] FIG. 6 is a block diagram showing the functional configuration of the RFID tag communication device according to the embodiment. [Figure 7] FIG. 7 is a diagram showing an example of a display screen of a display unit of a device for communicating with a radio tag according to an embodiment. [Figure 8] FIG. 8 is a flowchart showing the flow of a long-distance search process by the control unit of the RFID tag communication device in the embodiment. [Figure 9] FIG. 9 is a flowchart showing the flow of a short-distance search process by the control unit of the RFID tag communication device according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, a radio-frequency tag communication device and a program according to an embodiment will be described with reference to the drawings. Fig. 1 is a diagram for explaining a usage form of the radio-frequency tag communication device according to the embodiment. The radio-frequency tag communication device 1 outputs a carrier wave (radio wave) to a radio-frequency tag 21 attached to an item 20, and receives a response wave (radio wave) in response to the carrier wave from the radio-frequency tag 21, thereby reading tag information stored in the radio-frequency tag 21.

[0010] The articles 20 are, for example, merchandise stored in a retail store warehouse or documents stored in a bookcase. There are a large number of articles 20, and a wireless tag 21 is attached to each of the articles 20. Identification information 23 that enables the wireless tag 21 to be distinguished from other wireless tags 21 is stored in a memory unit 22 of the wireless tag 21. The wireless tag 21 is a passive tag that is activated upon receiving a carrier wave from the wireless tag communication device 1 and outputs a response wave in response to the carrier wave. The carrier wave is also called a query wave. In this way, the wireless tag communication device 1 communicates with the wireless tag 21 attached to each article 20 and searches for the location of the wireless tag 21 having the specific identification information 23, i.e., the location of the article 20.

[0011] The wireless tag communication device 1 is an RFID reader or the like that can be carried by a user, and includes a handle portion 2, an antenna portion 3, a display portion 4, and an operation portion 5.

[0012] The handle portion 2 is a portion that is gripped by the user during use and is formed in a shape that protrudes downward. The user can grip the handle portion 2 to point the antenna portion 3 in any direction.

[0013] The antenna unit 3 is formed in a thin rectangular parallelepiped shape and has a planar antenna 31 (see FIG. 5) inside. The antenna 31 transmits and receives radio waves to and from the wireless tag 21. Specifically, the antenna 31 outputs a carrier wave including identification information and the like of the wireless tag 21, and receives a reply wave output by the antenna 24 (see FIG. 3) of the wireless tag 21 in response to the carrier wave. The surface of the antenna unit 3 opposite the handle unit 2 is an antenna surface 32 formed in a planar shape. The antenna 31 outputs a carrier wave via the antenna surface 32, and receives a reply wave from the antenna 24 of the wireless tag 21 via the antenna surface 32.

[0014] The display unit 4 is configured, for example, with a liquid crystal panel, and displays various information. For example, the display unit 4 displays the distance between the RFID tag communication device 1 and the RFID tag 21 to be searched for, the direction in which the RFID tag 21 to be searched for is located, etc. The display unit 4 also displays a screen for accepting user operations, such as an input screen for inputting identification information of the RFID tag 21 to be searched for.

[0015] The operation unit 5 is configured with a touch panel provided on the surface of the display unit 4, and inputs information according to the touched position to the control unit 10 (see FIG. 5) of the RFID tag communication device 1. In response to a user's operation, the operation unit 5 inputs, for example, identification information of the RFID tag 21 to be searched for or information indicating the end of the search to the control unit 10.

[0016] The RFID tag communication device 1 is capable of switching the polarization direction of the carrier wave it outputs. Figure 2 is a diagram showing the relationship between the RFID tag communication device 1 and the polarization direction of the carrier wave. The RFID tag communication device 1 outputs a first carrier wave as a vertically polarized wave whose polarization direction is vertical (first polarization direction A). The RFID tag communication device 1 also outputs a second carrier wave as a horizontally polarized wave whose polarization direction is horizontal (second polarization direction B).

[0017] More specifically, the RFID tag communication device 1 can perform searching operations in a dual polarization mode in which the first carrier wave and the second carrier wave are alternately transmitted from the antenna 31, or in a single polarization mode in which only the first carrier wave or the second carrier wave is transmitted. Here, the dual polarization mode in which the first carrier wave and the second carrier wave are alternately transmitted means an output mode in which the period for transmitting the first carrier wave and the period for transmitting the second carrier wave are alternately set.

[0018] Fig. 3 is a diagram showing an example of the relationship between the first polarization direction A and the antenna 24 of the wireless tag 21. The antenna 24 is, for example, a long and narrow dipole antenna arranged along the wireless tag 21, and extends in the vertical direction in the state of Fig. 3. As a result, the polarization direction of the antenna 24 is vertical.

[0019] When the RFID tag communication device 1 is outputting the first carrier wave in the first polarization direction A, if the polarization direction of the antenna 24 of the RFID tag 21 is vertical as shown in Fig. 3, that is, if the polarization direction of the antenna 24 matches the polarization direction of the carrier wave, the antenna 24 will likely receive the first carrier wave and activate the RFID tag 21. Conversely, if the antenna 24 is arranged horizontally, the RFID tag 21 will likely not activate.

[0020] Fig. 4 is a diagram showing an example of the relationship between the second polarization direction B and the antenna 24 of the wireless tag 21. In the state shown in Fig. 4, the polarization direction of the antenna 24 is horizontal. When the wireless tag communication device 1 outputs the second carrier wave in the second polarization direction B, the wireless tag 21 is likely to be activated if the polarization direction of the antenna 24 is horizontal as shown in Fig. 4. Conversely, if the antenna 24 is arranged vertically, the wireless tag 21 is unlikely to be activated.

[0021] When the wireless tag 21 is activated by a carrier wave, it outputs a response wave in response to the carrier wave, and the wireless tag communication device 1 can receive the response wave and read the tag information of the wireless tag 21. In other words, the closer the polarization direction of the antenna 24 of the wireless tag 21 is to the polarization direction of the carrier wave, the easier it is for the wireless tag communication device 1 to read the tag information of the wireless tag 21.

[0022] In the initial stage of the search when the positional relationship between the antenna 31 of the radio tag communication device 1 and the antenna 24 of the radio tag 21 being searched for is unknown, the probability that the radio tag communication device 1 will read the tag information of the radio tag 21 can be increased by alternately switching between the first polarization direction A and the second polarization direction B at predetermined intervals.

[0023] Next, a description will be given of the hardware configuration of the RFID tag communication device 1. Fig. 5 is a block diagram showing the hardware configuration of the RFID tag communication device 1. The RFID tag communication device 1 includes a control unit 10, a memory unit 11, an antenna 31, a display unit 4, an operation unit 5, a sensor 12, a power supply circuit 13, a battery 14, and a communication unit 15. The control unit 10, the memory unit 11, the antenna 31, the display unit 4, the operation unit 5, the sensor 12, the power supply circuit 13, and the communication unit 15 are connected to each other via a bus 16 or the like so as to be able to communicate with each other.

[0024] The control unit 10 is configured as a computer including a CPU (Central Processing Unit) 101, a ROM (Read Only Memory) 102, and a RAM (Random Access Memory) 103. The CPU 101, the ROM 102, and the RAM 103 are connected to each other via a bus 16.

[0025] The CPU 101 controls the entire RFID tag communication device 1. The ROM 102 stores various programs, such as a program used to drive the CPU 101, and various data. The RAM 103 has a comparison result storage unit 1031. The comparison result storage unit 1031 stores information related to the radio wave intensity of a response wave (first response wave) from the RFID tag 21 to a first carrier wave transmitted from the antenna 31 and a response wave (second response wave) from the RFID tag 21 to a second carrier wave. For example, the comparison result storage unit 1031 stores a comparison result between the radio wave intensity of the first response wave and the radio wave intensity of the second response wave. The RAM 103 is used as a work area for the CPU 101, and loads various programs and data stored in the ROM 102 and the memory unit 11. The control unit 10 executes various control processes of the RFID tag communication device 1 by the CPU 101 operating in accordance with the control programs stored in the ROM 102 and the memory unit 11 and loaded in the RAM 103.

[0026] The memory unit 11 is configured with a storage medium such as a hard disk drive (HDD) or flash memory, and maintains its stored contents even when the power is turned off. The memory unit 11 stores a control program 111 and a reference value file 112.

[0027] The control program 111 is a control program for realizing various functions of the RFID tag communication device 1, etc.

[0028] The reference value file 112 stores a reference value used to control the carrier waves transmitted by the antenna 31. Specifically, the reference value file 112 stores a set number X that is a condition for switching from a dual polarization mode in which the first carrier wave and the second carrier wave are transmitted alternately to a single polarization mode in which only either the first carrier wave or the second carrier wave is transmitted.

[0029] The set number of times X is a reference value related to the comparison result between the radio wave strength of the first response wave for the first carrier wave and the radio wave strength of the second response wave for the second carrier wave output after the first carrier wave in a dual polarization mode in which the first carrier wave and the second carrier wave are transmitted alternately. In the dual polarization mode, the period in which the first carrier wave is output and the period in which the second carrier wave is output are output alternately and continuously. Therefore, the comparison between the radio wave strength of the first response wave for the first carrier wave and the radio wave strength of the second response wave for the second carrier wave output after the first carrier wave is performed multiple times.

[0030] The set number of times X defines a reference value for the number of times that the radio wave strength of either the first response wave or the second response wave is consecutively higher than the radio wave strength of the other. As a result of comparing the radio wave strengths of the first response wave and the second response wave in both polarization modes, if the radio wave strength of the first response wave is consecutively higher than the radio wave strength of the second response wave for at least the set number of times X, for example, the control unit 10 controls in a single polarization mode in which the first carrier wave is continuously transmitted.

[0031] The first response wave is, for example, a response wave received during the period when the RFID tag communication device 1 is outputting the first carrier wave. The radio wave intensity of the first response wave can be, for example, the average value of the response wave received during the period when the first carrier wave is output. Similarly, the second response wave is, for example, a response wave received during the period when the RFID tag communication device 1 is outputting the second carrier wave. The radio wave intensity of the second response wave can be, for example, the average value of the response wave received during the period when the second carrier wave is output.

[0032] The configurations and functions of the antenna 31, the display unit 4, and the operation unit 5 are as described above.

[0033] The sensor 12 detects the direction in which the RFID tag communication device 1 is facing. The sensor 12 includes sensor devices such as a direction sensor and an angle sensor, as well as a calculation unit that calculates the orientation of the RFID tag communication device 1 based on the detection values of the sensor devices.

[0034] The power supply circuit 13 is connected to the battery 14. The power supply circuit 13 is a circuit that supplies power to each piece of hardware in the RFID tag communication device 1. The power supply circuit 13 supplies power to each piece of hardware by, for example, stepping down the voltage supplied from the battery 14 to the operating voltage of each piece of hardware. The battery 14 can be charged by being connected to a commercial power source via a charging device (not shown).

[0035] The communication unit 15 is an interface for communicating with an external device such as a management PC. The management PC stores, for example, information about each item 20 (such as product name) and identification information of the wireless tag 21 attached to each item 20 in association with each other. The control unit 10 is connected to an external device via the communication unit 15, thereby enabling transmission and reception of information (data) with the external device. The control unit 10 can receive identification information for identifying the wireless tag 21 to be searched from the management PC via the communication unit 15.

[0036] Next, a description will be given of the functional configuration of the RFID tag communication device 1. Fig. 6 is a block diagram showing the main functional configuration of the control unit 10 of the RFID tag communication device 1. The control unit 10 functions as a reception unit 1001, an identification unit 1002, a radio wave control unit 1003, a radio wave information processing unit 1004, a comparison unit 1005, a search mode switching unit 1006, and a display control unit 1007, as a result of the CPU 101 operating in accordance with a control program stored in the ROM 102 or memory unit 11. Note that each of these functions may be configured using hardware such as a dedicated circuit.

[0037] The reception unit 1001 receives identification information for identifying the wireless tag 21 to be searched for. Specifically, the reception unit 1001 receives identification information input to the operation unit 5 or identification information input from the management PC via the communication unit 15. The identification information is information for identifying the wireless tag 21 to be searched for, and is stored in the wireless tag 21. The identification information may identify (specify) one wireless tag 21, or may identify multiple wireless tags 21.

[0038] For example, when the wireless tags 21 are attached to products, the information used to identify the multiple wireless tags 21 includes information indicating a product code or an SKU (Stock Keeping Unit). The product code is a code that identifies the product, and the information indicating the SKU is information that identifies the product management unit set by the user. The wireless tag 21 attached to the product stores information indicating the individual product, such as the product's serial number, and information indicating the product code or SKU. This allows the user to specify the wireless tag 21 to be searched for on an individual product basis or on a product classification basis, such as a product code or SKU. The receiving unit 1001 also receives instruction information input to the operation unit 5 to instruct the start or end of a search for an item. The receiving unit 1001 also receives various other information input to the control unit 10.

[0039] The identification unit 1002 identifies the wireless tag 21 to be searched for and generates search information for searching for the wireless tag 21 to be searched for. For example, the identification unit 1002 generates information including a command for specifying the identification information received by the reception unit 1001 and communicating with the wireless tag 21 to be searched for. The identification information can be specified using a specific command.

[0040] The radio wave control unit 1003 switches the carrier wave between a first carrier wave transmitted in a first polarization direction A and a second carrier wave transmitted in a second polarization direction B. For example, the radio wave control unit 1003 causes the antenna 31 to transmit the carrier wave in a single polarization mode when starting a search for the wireless tag 21 identified by the identification information received by the receiving unit 1001. Note that the radio wave control unit 1003 may also control the carrier wave in both polarization modes when starting a search for the wireless tag 21.

[0041] Furthermore, when the antenna 31 does not receive a reply wave for a carrier wave in a single polarization mode while controlling the carrier wave, the radio wave control unit 1003 switches to a dual polarization mode. Depending on the location of the wireless tag 21 to be searched, the wireless tag 21 may not be activated by a carrier wave in one polarization direction, so the radio wave control unit 1003 also causes the antenna 31 to transmit a carrier wave in the other polarization direction as necessary.

[0042] Furthermore, while controlling the carrier waves in dual polarization mode, the radio wave control unit 1003 switches to single polarization mode when a comparison result between the radio wave strength of a first response wave for a first carrier wave and the radio wave strength of a second response wave for a second carrier wave output following the first carrier wave satisfies a certain condition. Specifically, in dual polarization mode, when the radio wave strength of one of the first response wave or the second response wave is higher than the radio wave strength of the other a set number of times, X, in succession, the radio wave control unit 1003 switches from dual polarization mode to single polarization mode using the carrier wave corresponding to the response wave with the higher radio wave strength.

[0043] More specifically, as a result of repeatedly comparing the radio wave strength of the first response wave with the radio wave strength of the second response wave in both polarization modes, if the radio wave strength of the first response wave is higher than the radio wave strength of the second response wave for a set number of times, X times in a row, the radio wave control unit 1003 switches to a single polarization mode using the first carrier wave.

[0044] If the radio wave intensity of one reply wave remains higher than the radio wave intensity of the other reply wave, it is estimated that the user is approaching the search target radio tag 21 while maintaining the same relationship between the orientation of the antenna 31 of the radio tag communication device 1 and the orientation of the antenna 24 of the radio tag 21. It is then considered that the radio tag communication device 1 can communicate with the radio tag 21 using only the carrier wave with the high radio wave intensity of the reply wave. Therefore, in this state, the radio wave control unit 1003 continuously outputs a carrier wave in one polarization direction. This stops the output of the carrier wave that does not contribute to reading tag information, thereby shortening the time required to read tag information and enabling efficient reading.

[0045] Furthermore, the radio wave control unit 1003 controls the output value (radio wave intensity) of the carrier wave output from the antenna 31. The radio wave control unit 1003 controls the output of the carrier wave in multiple stages within a preset range. Here, if the radio tag 21 is activated by the carrier wave output from the radio tag communication device 1 and the radio tag communication device 1 receives a reply wave from the radio tag 21, this is also referred to as "communication being successful." On the other hand, if the radio tag communication device 1 does not receive a reply wave in response to the carrier wave output by its own device, this is also referred to as "communication being unsuccessful."

[0046] If communication is successful a preset number of times in succession in single polarization mode or dual polarization mode, the radio wave control unit 1003 determines that the radio tag 21 being searched for is present within the readable range of the radio tag communication device 1, and lowers the output value of the carrier wave by one level. The radio tag communication device 1 narrows the readable range by lowering the output value of the carrier wave while maintaining the state in which the radio wave control unit 1003 determines that the radio tag 21 is present within the readable range. This narrows down the location of the radio tag 21 being searched for.

[0047] Furthermore, if communication between the RFID tag communication device 1 and the RFID tag 21 is unsuccessful a preset number of times in succession, the radio wave control unit 1003 determines that the RFID tag 21 is not within the readable range and increases the output value of the carrier wave by one level. This makes it possible to read the tag information of the RFID tag 21 being searched for even if the user accidentally moves away from the RFID tag 21 being searched for.

[0048] The radio wave information processing unit 1004 executes various processes based on information of the reply wave received by the antenna 31. For example, the radio wave information processing unit 1004 determines whether the RF tag 21 to be searched for is within a tag information reading range of the RF tag communication device 1 based on the radio wave intensity of the reply wave. The radio wave information processing unit 1004 also estimates the distance between the RF tag communication device 1 and the RF tag 21 to be searched for and the direction of the RF tag 21 to be searched for based on the radio wave intensity of the reply wave. The radio wave information processing unit 1004 treats the reply wave received while the first carrier wave is being output as the first reply wave, and the reply wave received while the second carrier wave is being output as the second reply wave.

[0049] The comparison unit 1005 compares the radio wave intensity of the first response wave output by the wireless tag 21 in response to the first carrier wave with the radio wave intensity of the second response wave output by the wireless tag 21 in response to the second carrier wave. Specifically, in both polarization modes, the comparison unit 1005 compares the radio wave intensity of the first response wave received during the period in which the first carrier wave is output with the radio wave intensity of the second response wave received during the period in which the second carrier wave is output following the period in which the first carrier wave is output.

[0050] In the following description, a first carrier wave and a second carrier wave output subsequently thereto, i.e., a first carrier wave transmitted for a predetermined period and a second carrier wave transmitted subsequently thereto for a predetermined period, may be collectively referred to as a "paired carrier wave." Also, a first reply wave to a first carrier wave and a reply wave to a second carrier wave following the first carrier wave may be collectively referred to as a "paired reply wave." For example, when paired carrier waves are output 10 times in both polarization modes, the comparison unit 1005 compares the radio wave intensities of the paired reply waves 10 times.

[0051] In the single polarization mode, the comparison unit 1005 compares the radio wave intensity of the reply wave with 0. For example, in the single polarization mode using the first carrier wave, the comparison unit 1005 considers the radio wave intensity of the second reply wave to be 0, and compares the radio wave intensity of the first reply wave with the radio wave intensity of the second reply wave.

[0052] The search mode switching unit 1006 switches the operation mode for searching for the wireless tag 21 between a long-distance search mode and a short-distance search mode. Specifically, the search mode switching unit 1006 sets the long-distance search mode in which the output value of the carrier wave output from the antenna 31 is varied at the start of a search. In the long-distance search mode, the wireless tag communication device 1 narrows down the location of the wireless tag 21 to be searched for.

[0053] Furthermore, when the location of the wireless tag 21 to be searched for is narrowed down, the search mode switching unit 1006 sets the mode to a short-distance search mode in which the output value of the carrier wave output from the antenna 31 is kept constant.

[0054] The display control unit 1007 displays various information on the display unit 4. For example, the display control unit 1007 displays a display screen showing the direction in which the search target wireless tag 21 is located and the distance to the wireless tag 21, based on the radio wave intensity of the reply wave received by the antenna 31 and the output of the sensor 12.

[0055] 7 is a diagram showing an example of a display screen during a search for the wireless tag 21. A display screen 41 displays a tag position display section 42, a tag information display section 43, and an end button section 44.

[0056] The tag position display unit 42 shows the positional relationship between the device itself and the wireless tag 21 that is the search target. The tag position display unit 42 displays concentric distance marks. The center 421 of the concentric distance marks indicates the position of the device itself, and the outer circles indicate the greater the distance from the device itself. The tag position display unit 42 displays a tag position unit 422 that indicates the position of the wireless tag 21 that is the search target at a position farther away from the center 421 of the concentric circles.

[0057] The tag information display unit 43 displays information about the wireless tag 21 to be searched and the article to which the wireless tag 21 is attached. For example, the tag information display unit 43 displays identification information stored in the wireless tag 21 to be searched and the name of the article to which the wireless tag 21 is attached.

[0058] The end button section 44 displays an end button. The end button is an operation button for instructing the end of the search for the wireless tag 21. When the end button is operated while the wireless tag communication device 1 is operating in the long-distance search mode or the short-distance search mode, the wireless tag communication device 1 stops outputting the carrier wave from the antenna 31 and ends the search in the search mode.

[0059] Next, a search process for the search target RF tag 21 will be described. Fig. 8 is a flowchart showing the flow of the long-distance search process by the control unit 10 of the RF tag communication device 1.

[0060] When a user operates the operation unit 5 to input identification information of the wireless tag 21 to be searched for, the reception unit 1001 receives the identification information (step S1). Subsequently, the identification unit 1002 identifies the wireless tag 21 to be searched for based on the identification information received by the reception unit 1001, and generates search information for searching for the wireless tag 21 (step S2).

[0061] The radio wave control unit 1003 sets the polarization direction of the carrier wave to one polarization direction (step S3). The polarization direction to be set is either the first polarization direction A or the second polarization direction B, which is set in advance. In other words, the radio wave control unit 1003 sets one polarization mode using either the first carrier wave or the second carrier wave. In this embodiment, it is assumed that the one polarization mode using the first polarization direction A is set.

[0062] Next, the radio wave control unit 1003 outputs a carrier wave including the search information generated by the identification unit 1002 from the antenna 31 in the set polarization direction (step S4). Specifically, at the start of the search, the radio wave control unit 1003 causes the antenna 31 to transmit the carrier wave in a single polarization mode using the first polarization direction set in step S3, more specifically, in a single polarization mode using the first carrier wave.

[0063] The control unit 10 determines whether the antenna 31 has received a reply wave from the wireless tag 21 to be searched (step S5). Specifically, the control unit 10 determines whether radio wave information has been input from the antenna 31 to the radio wave information processing unit 1004. When the reply wave is received (Y in step S5), the radio wave information processing unit 1004 stores information indicating the carrier wave with the higher radio wave strength in the comparison result storage unit 1031 as a result of the comparison of the radio wave strengths of the paired reply waves by the comparison unit 1005 (step S6). Since the search starts in the single polarization mode using the first carrier wave, the comparison unit 1005 compares the radio wave strength of the first reply wave with 0, which is regarded as the value of the second reply wave. As a result, the comparison result storage unit 1031 stores information indicating the first carrier wave. Note that in the single polarization mode, the comparison by the comparison unit 1005 may be omitted. For example, in the case of a single polarization mode using the first carrier, the comparison unit 1005 may not perform the comparison, and the comparison result storage unit 1031 may store information indicating the first carrier.

[0064] Next, the radio wave control unit 1003 determines whether or not the radio wave intensity of the first response wave is higher than the radio wave intensity of the second response wave for a set number of consecutive times X as a result of the comparison by the comparison unit 1005 (step S7). Specifically, the radio wave control unit 1003 determines whether or not information indicating the first carrier wave has been stored consecutively in the comparison result storage unit 1031.

[0065] If the radio wave intensity of the first response wave is higher than the radio wave intensity of the second response wave for a set number of consecutive times X (Y in step S7), the radio wave control unit 1003 sets one polarization direction using the first polarization direction A (step S8). Next, the control unit 10 determines whether communication has been successful for a set number of consecutive times (step S9), and if successful (Y in step S9), determines whether the output value of the carrier wave is the minimum value of the multiple set levels (S10).

[0066] If it is the minimum value (Y in step S10), the search mode switching unit 1006 determines that the RF tag 21 to be searched for is located near the RF tag communication device 1, and transitions to the short-distance search mode.

[0067] In the processing of step S5, if the antenna 31 does not receive a response wave in response to the carrier wave transmitted (N in step S5), i.e., if the communication fails, the control unit 10 determines whether the set number of consecutive failures has been reached (step S11), and if not (N in step S11), returns to the processing of step S4.

[0068] If the set number of consecutive failures has been reached (Y in step S11), the radio wave control unit 1003 increases the output value of the carrier wave by one step and sets the carrier wave in both polarization directions (step S12). At this time, if the output value of the carrier wave is already at the maximum value, the radio wave control unit 1003 maintains the output value of the carrier wave at the maximum value. Then, the control unit 10 returns to the processing of step S4.

[0069] Furthermore, in the processing of step S7, if the state in which the radio wave strength of the first response wave is higher than the radio wave strength of the second response wave is not consecutively set number of times X (N in step S7), the radio wave control unit 1003 determines whether the radio wave strength of the second response wave is consecutively higher than the radio wave strength of the first response wave for set number of times X (step S13).

[0070] If the radio wave intensity of the second response wave is higher than the radio wave intensity of the first response wave for the set number of consecutive times X (Y in step S13), the radio wave control unit 1003 sets one polarization direction using the second polarization direction B (step S14). Then, the control unit 10 proceeds to the processing of step S9. If the state in which the radio wave intensity of the second response wave is higher than the radio wave intensity of the first response wave is not consecutively set number of times X (N in step S13), the control unit 10 skips the processing of step S14 and proceeds to the processing of step S9.

[0071] In the process of step S9, if communication has not been successful the set number of times in succession (N in step S9), the control unit 10 returns to the process of step S4.

[0072] In the process of step S10, if the output value of the carrier wave is not the minimum value (N in step S10), the radio wave control unit 1003 lowers the output value of the carrier wave by one level (S15). Then, the display control unit 1007 updates the display screen 41 of the display unit 4. The display control unit 1007 updates the display screen 41 so that the center 421 of the concentric circles of the tag position display unit 42 and the tag position unit 422 are closer to each other. Then, the control unit 10 returns to the process of step S4.

[0073] By the above process, when the RFID tag communication device 1 is in a situation where tag information of the RFID tag 21 to be searched for can be read using only one of the first and second carrier waves, it switches to continuously outputting only that one carrier wave. This stops the output of unnecessary carrier waves that do not contribute to reading tag information, allowing for efficient search for the RFID tag 21 to be searched for.

[0074] Next, the processing in the short-distance search mode will be described. Fig. 9 is a flowchart showing the flow of the short-distance search processing by the control unit 10 of the device 1 for communicating with a radio tag.

[0075] In the short-distance search mode, the radio wave control unit 1003 transmits a carrier wave from the antenna 31 at the minimum output value (step S21). The carrier wave at this time is output in the polarization direction immediately before transitioning to the short-distance search mode. Normally, at the stage of transitioning to the short-distance search mode, the orientations of the antenna 31 of the RFID tag communication device 1 and the antenna 24 of the RFID tag 21 to be searched for are constant. Therefore, as a result of the comparison by the comparison unit 1005, the radio wave strength of either the first response wave or the second response wave is higher than the radio wave strength of the other for the set number of consecutive times X. Therefore, normally, at the stage of transitioning to the short-distance search mode, a single polarization mode using the first carrier wave or the second carrier wave is set.

[0076] Next, the radio wave information processing unit 1004 determines whether the radio wave intensity of the response wave received by the antenna 31 has decreased compared to the radio wave intensity of the response wave for the previous carrier wave (step S22). If it has decreased (Y in step S22), the display control unit 1007 displays a warning screen on the display unit 4 (step S23). The warning screen notifies the user that the RFID tag communication device 1 is moving in a direction away from the RFID tag 21 that is the search target. This prompts the user to return the RFID tag communication device 1 to its original position.

[0077] Next, the control unit 10 determines whether an input to end the search for the wireless tag 21 has been made to the operation unit 5 (step S24), and if no input has been made (N in step S24), the control unit 10 returns to the processing of step S21. If an input to end the search has been made (Y in step S24), the control unit 10 ends the processing.

[0078] In the process of step S22, if the radio wave intensity has not decreased (N in step S22), the control unit 10 skips the process of step S23 and proceeds to the process of step S24.

[0079] As described above, the embodiment of the radio tag communication device 1 has an antenna 31 that transmits a carrier wave and receives a response wave output by the radio tag 21 in response to the carrier wave, and is a radio tag communication device 1 that can identify the position of the radio tag 21 to be searched for based on the radio wave intensity of the response wave received by the antenna 31, and is equipped with a radio wave control unit 1003 that switches the carrier wave to a first carrier wave transmitted in a first polarization direction A and a second carrier wave transmitted in a second polarization direction B, and a comparison unit 1005 that compares the radio wave intensity of the first response wave output by the radio tag 21 in response to the first carrier wave with the radio wave intensity of the second response wave output by the radio tag 21 in response to the second carrier wave, and the radio wave control unit 1003 switches between the first carrier wave and the second carrier wave based on the comparison result of the comparison unit 1005.

[0080] For example, the radio wave control unit 1003 can set the output mode of the carrier wave transmitted from the antenna 31 to a dual polarization mode in which the first carrier wave and the second carrier wave are transmitted alternately, or a single polarization mode in which only either the first carrier wave or the second carrier wave is transmitted.

[0081] This allows the RFID tag communication device 1 to switch the polarization direction of the carrier wave as needed, thereby enabling efficient search for the RFID tag 21 to be searched for.

[0082] In addition, in the dual polarization mode, the comparison unit 1005 compares the radio wave strength of the first response wave transmitted by the wireless tag 21 in response to the first carrier wave with the radio wave strength of the second response wave transmitted by the wireless tag 21 in response to the second carrier wave transmitted following the first carrier wave, and if the comparison by the comparison unit 1005 shows that the radio wave strength of either the first response wave or the second response wave is higher than the radio wave strength of the other wave for a predetermined number of times X or more, the radio wave control unit 1003 switches to the single polarization mode in which the carrier wave for the response wave with the higher radio wave strength is continuously transmitted.

[0083] As a result, when a situation arises during a search in dual polarization mode where tag information of the search target RF tag 21 can be read using only one of the first and second carrier waves, the carrier wave output mode is switched to single polarization mode using the selected carrier wave. This makes it possible to automatically switch to outputting only the carrier wave that contributes to reading tag information, thereby improving the operability of the RF tag communication device 1.

[0084] Furthermore, the radio wave control unit 1003 of the device 1 for communicating with a radio tag according to the embodiment switches to the dual polarization mode when the antenna 31 does not receive a reply wave in the single polarization mode.

[0085] As a result, if the position of the RFID tag communication device 1 relative to the RFID tag 21 being searched for changes during a search in the single polarization mode, causing the RFID tag communication device 1 to be unable to read tag information, the output mode of the carrier wave is switched to the dual polarization mode. This makes it possible to switch to the dual polarization mode as needed, thereby improving operability in this respect as well.

[0086] In addition, the embodiment of the radio tag communication device 1 further includes a reception unit 1001 that receives identification information that identifies the radio tag 21 to be searched for, and the radio wave control unit 1003 is set to single polarization mode when starting to search for the radio tag 21 identified by the identification information received by the reception unit 1001.

[0087] As a result, if the tag information of the search target RF tag 21 can be read in single polarization mode at the start of the search, the search can be performed in single polarization mode from the start to the end, making the search extremely efficient. Also, if the tag information of the search target RF tag 21 cannot be read in single polarization mode at the start of the search, the mode will automatically switch to dual polarization mode, so operability will not be reduced.

[0088] In the above embodiment, the control program executed by the RFID tag communication device 1 may be provided by being recorded on a computer-readable recording medium such as a CD-ROM. Also, the control program executed by the RFID tag communication device 1 of the above embodiment may be provided by being stored on a computer connected to a network such as the Internet and downloaded via the network, or may be provided via a network such as the Internet.

[0089] Although the embodiment of the present invention has been described above, this embodiment is presented as an example and is not intended to limit the scope of the invention. This embodiment can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. [Explanation of symbols]

[0090] 1. Radio tag communication device 4 Display 21 Radio tag 31 Antenna 1001 Reception 1003 Radio Control Unit 1005 Comparison section A First polarization direction B Second polarization direction [Prior art documents] [Patent documents]

[0091] [Patent Document 1] Patent No. 5750524

Claims

1. A wireless tag communication device has an antenna that transmits a carrier wave and receives a response wave output from a wireless tag in response to the carrier wave, and is capable of identifying the position of a wireless tag to be searched for based on the radio wave intensity of the response wave received by the antenna, a radio wave control unit that switches the carrier wave between a first carrier wave transmitted in a first polarization direction and a second carrier wave transmitted in a second polarization direction, and that can be set to a dual polarization mode in which the first carrier wave and the second carrier wave are transmitted alternately, or a single polarization mode in which either the first carrier wave or the second carrier wave is transmitted; a comparison unit that compares the radio wave intensity of a first response wave output by the wireless tag in response to the first carrier wave with the radio wave intensity of a second response wave output by the wireless tag in response to the second carrier wave; Equipped with the radio wave control unit, when the antenna fails to receive the reply wave a preset number of times in succession, increases the output value of the carrier wave by one level and sets the antenna to the dual polarization mode, and when the antenna succeeds in receiving the reply wave a preset number of times in succession, decreases the output value of the carrier wave by one level and sets the antenna to the single polarization mode based on the comparison result of the comparison unit. Radio tag communication device.

2. the comparison unit compares, in the dual polarization mode, the radio wave intensity of a first response wave transmitted by the wireless tag in response to a first carrier wave with the radio wave intensity of a second response wave transmitted by the wireless tag in response to a second carrier wave transmitted subsequent to the first carrier wave; When the comparison result by the comparison unit indicates that the radio wave intensity of either the first reply wave or the second reply wave is higher than the radio wave intensity of the other for a preset number of times or more, the radio wave control unit switches to a single polarization mode in which a carrier wave for the reply wave with the higher radio wave intensity is continuously transmitted. The radio tag communication device according to claim 1 .

3. a reception unit for receiving identification information for identifying the wireless tag to be searched for; The radio wave control unit sets the single polarization mode when starting a search for a wireless tag identified by the identification information received by the reception unit. The radio tag communication device according to claim 1 .

4. A program for controlling, by a computer, a radio tag communication device that has an antenna that transmits a carrier wave and receives a response wave output from a radio tag in response to the carrier wave, and that can identify the position of a radio tag to be searched for based on the radio wave intensity of the response wave received by the antenna, The computer a radio wave control unit that switches the carrier wave between a first carrier wave transmitted in a first polarization direction and a second carrier wave transmitted in a second polarization direction, and that can be set to a dual polarization mode in which the first carrier wave and the second carrier wave are transmitted alternately, or a single polarization mode in which either the first carrier wave or the second carrier wave is transmitted; a comparison unit that compares the radio wave intensity of a first response wave output by the wireless tag in response to the first carrier wave with the radio wave intensity of a second response wave output by the wireless tag in response to the second carrier wave; It functions as the radio wave control unit, when the antenna fails to receive the reply wave a preset number of times in succession, increases the output value of the carrier wave by one level and sets the antenna to the dual polarization mode, and when the antenna succeeds in receiving the reply wave a preset number of times in succession, decreases the output value of the carrier wave by one level and sets the antenna to the single polarization mode based on the comparison result of the comparison unit. program.

Images