WIRELESS TAG READING DEVICE AND WIRELESS TAG INFORMATION PROCESSING SYSTEM

In an embodiment, a wireless tag reading checkout apparatus checkout apparatus includes a conveyor to convey objects with wireless tags attached thereto. An antenna is arranged along a portion of the conveyor and is configured to transmit an interrogation wave for reading wireless tags and then to receive a response wave from the wireless tags. A controller calculates changes in a phase difference between the interrogation wave and a response wave from a wireless tag over a time period corresponding to the conveyance of an object by the conveyor. The controller can identify whether the wireless tag responding to the interrogation wave is on an object being conveyed by the conveyor by using the calculated changes in the phase difference.

CROSS-REFERENCE TO RELATED APPLICATION

This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2019-210460, filed Nov. 21, 2019, the entire contents of which are incorporated herein by reference.

FIELD

Embodiments described herein relate generally to a wireless tag reading device and a wireless tag information processing system.

BACKGROUND

In recent years, an RFID (Radio Frequency Identification) technique has been used in a distribution system, a logistics system, and the like, to read information concerning articles or commodities from RFID tags (also referred to as wireless tags) and process the information.

For example, in a volume retailer such as a supermarket, a checkout system including a checkout machine and a conveying mechanism such as a conveyor belt is used. The conveying mechanism includes a wireless tag reading device that reads tag information from a wireless tag attached to a commodity on the conveying mechanism. The checkout machine performs a payment process based on the tag information read by the wireless tag reading device. With such a checkout system, a store clerk does not need to input commodity information manually, and thus can easily and quickly complete the payment process.

As such a wireless tag reading device with an antenna device integrated with a conveying mechanism is known. The integrated antenna device-conveying mechanism includes a base, a slider mechanism that includes a plurality of rollers and conveys a commodity. An antenna is disposed between the base and the slider mechanism. The antenna receives a radio signal from the wireless tags attached to the commodities conveyed along the slider. The structure of the antenna device is simplified and does not have a tunnel-like cover that partially covers the slider.

However, a wireless tag reading device of this type, which reads tag information in a non-enclosed space, may sometimes receive a radio signal from a nearby wireless tag not being conveyed by the conveying mechanism, e.g., a wireless tag attached to a commodity placed or passing near the conveying mechanism, perhaps on a neighboring conveying mechanism or the like. As a result, if such a reading device is applied to a checkout system, a commodity that a customer does not intend to purchase may be considered as a commodity to be purchased and an erroneous registration may occur. Accordingly, there is a need for a technique that can distinguish a target wireless tag being conveyed by a conveying mechanism and a non-target wireless tag such as a wireless tag attached to a commodity conveyed by neighboring conveying mechanism.

DETAILED DESCRIPTION

Embodiments provide a wireless tag reading device and a wireless tag information processing system capable of distinguishing a target wireless tag from a non-target wireless tag.

According to one embodiment, a wireless tag reading checkout apparatus includes a conveyor configured to convey objects with wireless tags attached thereto and an antenna arranged along a portion of the conveyor. The antenna is configured to transmit an interrogation wave for reading wireless tags and to receive a response wave from the wireless tags. A controller is configured to calculate changes in a phase difference between the interrogation wave and a response wave from a wireless tag over a time corresponding to the conveyance of an object by the conveyor, and then identify whether the wireless tag responding to the interrogation wave is on the object conveyed by the conveyor using the calculated changes in the phase difference.

A checkout system in one or more embodiments is explained below with reference to the drawings.FIG. 1is a diagram illustrating a checkout system1. The checkout system1is used by a volume retailer or the like and includes a wireless tag reading device2and a checkout device3.

As illustrated inFIG. 2, the wireless tag reading device2includes a conveying unit2A and a reading unit2B. The conveying unit2A conveys a commodity that a customer is about to purchase. As illustrated inFIGS. 2 and 3, the conveying unit2A includes a base4and a receiving table5. The base4is supported by a plurality of supporting legs6and includes a conveying mechanism7therein. The conveying mechanism7includes upper and lower rollers8, a conveying belt9laid over the rollers8, a motor52(seeFIG. 4) that drives any one of the rollers8, and a control unit20(seeFIG. 4) that controls the motor52. The roller8is driven by the motor52, whereby the conveying belt9rotates and conveys a commodity G placed on the conveying belt9in an arrow direction shown inFIGS. 2 and 3. A part of the conveying belt9exposed on the upper surface of the base4is referred to a conveying path9A. A wireless tag R is attached to the commodity G.

The conveying unit2A includes a human sensor10, start point sensors11, and end point sensors12. The sensors10to12are attached to the base4. The human sensor10is attached to the wireless tag reading device2where the customer is located when starting checkout processing, i.e., at the left end inFIG. 2, and detects the customer. If the human sensor10detects the customer, the motor52is driven and the conveying belt9rotates.

The start point sensors11are disposed at a start point of a section X, which is a particular section or region of the conveying path9A. The start point sensors11detect a commodity being conveyed by the conveying belt9past the start point of the section X. The end point sensors12are disposed at an end point of the section X and detect the commodity conveyed by the conveying belt9past the end point of the section X. It is explained more particularly below how detection results by the start point sensors11and the end point sensors12are used. In an embodiment, optical sensors are used as the human sensor10, the start point sensors11, and the end point sensors12. However, various sensor types such as image sensors or cameras may be used.

The receiving table5is supported by supporting legs13in the position at the end of the conveying mechanism7. The receiving table5includes a slope section14and a placing section15on the upper surface thereof. The commodity moves along the conveying belt9and eventually drops from the conveying belt9to the slope section14and reaches the placing section15.

The reading unit2B includes an antenna16and a metal plate17, which reflects a radio wave. The antenna16is provided below the conveying path9A and is positioned in approximately the midpoint of the section X along the conveying direction (large arrow direction inFIG. 2) of the conveying mechanism7. The metal plate17is located on the lower side of the antenna16. A part of the metal plate17partially overlaps with the antenna16. The metal plate17is offset to the downstream side of the antenna16in the conveying direction. The wireless tag reading device2emits a radio wave having a frequency in a UHF (Ultra High Frequency) band.

The checkout device3is provided near an end portion of the conveying mechanism7. The checkout device3is a self-service checkout device with which the customer performs a payment process by himself or herself. InFIG. 2, the customer is indicated by the reference symbol “C”, and a shopping cart used by the customer is indicated by the reference symbol “SC”.

A hardware configuration of the wireless tag reading device2is explained with reference toFIG. 4. The wireless tag reading device2includes the control unit20, a storage unit30, an equipment controller40, a communication I/F (Interface)50, and the like. The control unit20, the storage unit30, the equipment controller40, and the communication I/F50are connected to one another via a bus51.

The control unit20includes a CPU (Central Processing Unit)21, a ROM (Read Only Memory)22, and a RAM (Random Access Memory)23. The CPU21, the ROM22, and the RAM23are connected to one another via the bus51. The CPU21is a processor for executing functions of the wireless tag reading device2. The ROM22stores various programs. Various programs and various data stored in the ROM22and the storage unit30are loaded in the RAM23. The CPU21executes a control program(s) stored in the ROM22or the storage unit30and loaded in the RAM23, whereby the control unit20executes various kinds of control processing for the wireless tag reading device2.

The storage unit30includes a control program area that stores various control programs. The equipment controller40is connected to the antenna16, the motor52, the human sensor10, the start point sensors11, and the end point sensors12. The communication I/F50is connected to the checkout device3. Consequently, the wireless tag reading device2is capable of transmitting and receiving information to and from the checkout device3.

A functions performed by the control unit20of the wireless tag reading device2is explained with reference toFIG. 5. The CPU21executes a control program(s) stored in the ROM22or the control program area31of the storage unit30, whereby the control unit20functions as a first sensor input unit201, a motor control unit202, a radio-wave control unit203, a radio-wave-information processing unit204, and a radio-wave-information output unit205.

Information detected by the human sensor10, the start point sensors11, and the end point sensors12is input to the first sensor input unit201. The motor control unit202controls the motor52based on information input from the first sensor input unit201. Specifically, if information indicating that the human sensor10detects the customer is input to the motor control unit202from the first sensor input unit201, the motor control unit202starts driving of the motor52. If information indicating that a fixed time has elapsed from when the end point sensors12detected a commodity is input to the motor control unit202from the first sensor input unit201, the motor control unit202stops the driving of the motor52.

The radio-wave control unit203outputs a control signal to the antenna16based on information input from the first sensor input unit201. Specifically, if the first sensor input unit201receives, from the conveying unit2A, a start notification, that is, information indicating that the start point sensors11detect a commodity, the radio-wave control unit203outputs a control signal to the antenna16to cause the antenna16to transmit an interrogation wave (also referred to as transmission wave or a carrier wave) at a predetermined interval or continuously. If the information indicating that the fixed time has elapsed from when the end point sensors12detected a commodity is input to the radio-wave control unit203from the first sensor input unit201, the radio-wave control unit203outputs a control signal to the antenna16to cause the antenna16to stop the output of the interrogation wave.

The radio-wave information processing unit204generates and stores radio wave information of a transmission wave transmitted by the antenna16and a response wave received by the antenna16from a wireless tag. The radio wave information, in this context, is information with which a phase difference between the transmission wave and the response wave (that is, a phase difference of the response wave with respect to the transmission wave) can be calculated. In an embodiment, the radio wave information is information with which the waveforms of the transmission wave and the response wave can be specified. The radio wave information also includes wireless tag information (e.g., a tag ID and/or product code) included in the response wave. The radio-wave-information output unit205outputs information stored by the radio-wave-information processing unit204to the checkout device3.

A hardware configuration of the checkout device3is explained with reference toFIG. 6. The checkout device3is a POS (Point Of Sales) terminal and includes a control unit60, a storage unit70, an equipment controller80, a communication I/F (Interface)90, and the like. The control unit60, the storage unit70, the equipment controller80, and the communication I/F90are connected to one another via a bus91.

The control unit60includes a CPU61, a ROM62, and a RAM63. The CPU61, the ROM62, and the RAM63are connected to one another via the bus91. The CPU61is a processor for executing functions of the checkout device3according to program instructions. The ROM62stores various programs. Various programs and various data stored in the ROM62and the storage unit70are loaded in the RAM63. The CPU61executes a control program(s) stored in the ROM62or the storage unit70and loaded in the RAM63, whereby the control unit60executes various kinds of control processing for the checkout device3.

The storage unit70includes a control program area71, a commodity master area72, and a phase-difference storing area73. The control program area71stores various control programs and the like concerning a payment process. The commodity master area72stores a commodity master. In this context, commodity master is a master file in which product names, prices, and the like for commodities are stored in association with commodity codes. In general, since the commodity master includes a list of all items available for purchase at the store location, it is updated at least every day.

The phase-difference storing area73stores phase difference data. Specifically, the phase-difference storing area73stores time-series data concerning a reference value of a phase difference, a first range and a second range concerning the time-series data, and the like. The reference value is a value determined in advance based on experiment(s) performed using the wireless tag reading device2. The reference value is a value obtained by measuring a phase difference between a transmission wave from the antenna16and a response wave from the wireless tag whiled the wireless tag is moved in the section X by the conveying mechanism7, (see a curve T inFIG. 9). The first range is a range of ±20% from the reference value and is the range in which it is considered it can be safely determined, considering various possible errors and tolerances, that the responding wireless tag is being conveyed by the conveying unit2A. The second range is a range of ±30% from the reference value and is the range in which it is possible, but not certain the responding wireless tag is conveyed by the conveying unit2A. If the time-series data of the phase difference is in the first range concerning the same wireless tag, the time-series data satisfies a first condition. If the time-series data is not included in the first range, but is included in the second range, the time-series data satisfies a second condition.

The control program(s) may be provided via a non-transitory computer-readable recording medium such as a CD-ROM or the like. The control program(s) executed by the wireless tag reading device2and the checkout device3may be stored on a computer connected to a network such as the Internet and downloaded through the network. Further, the control program(s) may be stored in the computer and executed through a network such as the Internet.

The equipment controller80is connected to a touch panel81, a coin change machine82, and a printer83. The touch panel81displays various kinds of information necessary when the customer makes payment, such as a total amount, commodity names, and unit prices, and receives operation by the customer. The coin change machine82stores bills and coins paid by the customer and dispenses bills and coins to the customer as a change. The printer prints a receipt if the payment by the customer is completed. The communication I/F90is connected to the wireless tag reading device2. Consequently, the checkout device3is capable of transmitting and receiving information to and from the wireless tag reading device2.

Subsequently, functions performed by the control unit60of the checkout device3is explained with reference toFIG. 7. The CPU61executes a control program(s) stored in the ROM62or the control program area71of the storage unit70, whereby the control unit60functions as a radio-wave-information acquiring unit601, a second sensor input unit602, a tag-information recognizing unit603, a phase-difference calculating unit604, a time-series data acquiring unit605, a determining unit606, and a payment process unit607.

The radio-wave-information acquiring unit601acquires radio wave information output from the radio-wave-information output unit205of the wireless tag reading device2. A stop notification is input to the second sensor input unit602from the wireless tag reading device2based on detection by the end point sensors12. Specifically, if the end point sensors12has not detected a commodity for a particular time after previously detecting the commodity, the wireless tag reading device2determines that the wireless tag reading device2had read all commodities to be purchased by a customer, and inputs the stop notification to the second sensor input unit602.

The tag-information recognizing unit603recognizes, in the radio wave information acquired by the radio-wave-information acquiring unit601, from a response wave, wireless tag information, that is, information relating to a commodity to which the wireless tag is attached, such as a commodity code or an individual article code. The phase-difference calculating unit604calculates, from the radio wave information acquired by the radio-wave-information acquiring unit601, a phase difference between a transmission wave transmitted by the antenna16and a response wave received by the antenna16from the wireless tag. The phase-difference calculating unit604calculates, based on the radio wave information continuously acquired by the radio-wave-information acquiring unit601, phase differences between transmission waves and response waves responding to the transmission waves, and generates and outputs time-series data indicating the phase differences in time series.

The time-series data acquiring unit605acquires the time-series data that is output by the phase-difference calculating unit604. The determining unit606compares the time series data of the phase differences acquired by the time-series data acquiring unit605and the phase difference data stored in the phase-difference storing area73, and determines whether the time-series data satisfies the first condition, that is, the time-series data is included in the first range. Similarly, the determining unit606compares the time-series data of the phase differences acquired by the time-series data acquiring unit605and the phase difference data stored in the phase-difference storing area73, and determines whether the time series data satisfies the second condition, that is, the time-series data is not included in the first range but is included in the second range. If a phase difference concerning one wireless tag acquired by the time-series data acquiring unit605satisfies the first condition, the determining unit606determines that the wireless tag is conveyed by the conveying unit2A.

The payment process unit607performs a payment process for a commodity having the wireless tag that has been determined by the determining unit606as satisfying the first condition. The payment process unit607performs the payment process for the commodity having the wireless tag that has been determined by the determining unit606as satisfying the second condition when the customer has confirmed to purchase the commodity. The payment process includes display of a total amount relating to a transaction and printing of a receipt, which are usually performed by a POS terminal for checkout.

FIG. 8is a diagram illustrating a positional relation between a wireless tag reading device A and a wireless tag B.FIG. 8schematically illustrates a wireless tag B at a position “a,” which is a point near the wireless tag reading device A, and the wireless tag B at a position “b,” which a point far (at least relative to position “a”) from the wireless tag reading device A. InFIG. 8, the reference symbol “anA” indicates an antenna of the wireless tag reading device A and the reference symbol “anB” indicates an antenna of the wireless tag B.

Irrespective of whether the wireless tag B is present at the “a” point or present at the “b” point, if the wireless tag B receives a transmission wave from the wireless tag reading device A, the wireless tag B transmits a response wave. The wireless tag reading device A can receive the response wave and reads tag information included in the response wave. At this time, the distance between the “a” point and the “b” point and the wireless tag B is different by the moving distance Y (“route distance”) of the wireless tag B. Accordingly, a phase difference between the transmission wave from the wireless tag reading device A and the response wave received by the wireless tag reading device A from the wireless tag B is different between when the wireless tag B is located at the “a” point and when the wireless tag B is located at the “b” point. Since the “a” point is at a shorter distance from the wireless tag reading device A, a phase difference (a1) at the “a” point is less than a phase difference (b1) at the “b” point. This example embodiment focuses on calculating the moving distance of the wireless tag B based on the phase differences.

Here, the calculation of the moving distance of the wireless tag B in the case of a radio wave at 920 MHz in the UHF band is explained. In such a case, one wavelength is approximately 326 mm, and one wavelength corresponds to 360° in terms of a phase angle, and thus a distance per phase angle 1° increment is approximately 0.91 mm (=326/360). InFIG. 8, the difference between the phase difference a1 for wireless tag B located at the “a” point and the phase difference b1 for the wireless tag B located at the “b” point, is caused by a difference in total travel length of transmission and response signals (that is, twice the moving distance Y). Therefore, the moving distance Y from the “a” point to the “b” point can be calculated as (b1−a1)×0.91/2. In this way, the moving distance of the wireless tag can be calculated.

Subsequently, a method of determining whether a commodity is being conveyed by the conveying unit2A is explained.FIG. 9is a graph illustrating phase differences in time series concerning a wireless tag attached to a commodity moving through the section X inFIG. 2. InFIG. 9, the horizontal axis indicates a time (in seconds) from when the start point sensors11first detect the commodity. The horizontal axis is set to cover a range of a time in which the commodity is normally conveyed by the conveying unit2A from the start point to the end point of the section X. The vertical axis indicates the phase difference as explained above (that is, the phase difference between the transmission wave transmitted by the antenna16and the response wave received by the antenna16). The phase differences illustrated in the graph are values normalized based on the phase difference at the start point of the section X being set to 0. A phase difference value calculated at a predetermined interval is accumulated with respect to a reference value 0° and is a value subjected to so-called unwrap processing.

The curve T is a curve indicating time-series data of the reference values (reference data). As explained above, here the reference values are obtained by an experiment that measures a phase difference with respect to the time from the start point of the section X while the wireless tag is being moved by the conveying unit2A. Since the antenna16is not located on the conveying belt9, a moving distance of the commodity and a moving distance calculated based on the response wave direction by the wireless tag reading device2do not precisely coincide.

The curve T is not symmetrical because the values of curve T are affected by the presence of the metal plate17offset towards one side of the section X. If the metal plate17were not provided, the curve T would theoretically be symmetrical since the antenna16is provided in the center of the section X and the wireless tag moves at a constant speed.

However, since the transmission wave transmitted from the antenna16is being reflected by the metal plate17, a reflected wave of the transmission wave interferes with the response wave transmitted from the wireless tag or the response wave is transmitted from the wireless tag according to a reflected wave. Accordingly, since a disturbance occurs in the phase difference, the curve T is not symmetrical. The disturbance in the phase difference due to the metal plate17markedly appears when the wireless tag is near the metal plate17. The curve T thus has a peculiar shape as indicated by reference symbol “U” inFIG. 9.

The metal plate17is positioned to correspond to one part of the conveying path9A to identifiably vary the time-series data of the reference value for the phase difference according to a position of the wireless tag along the conveying unit2A. In other words, a radio wave reflector (metal plate17) strongly affecting the phase difference is provided in a part of the conveying path9A, but not all of the conveying path9A. As a result, the time-series data curve T of the reference value of the phase difference is asymmetrical. Consequently, the wireless tag reading device2can surely distinguish the wireless tag attached to the commodity being conveyed by the conveying unit2A from other wireless tags that are attached to commodities not being conveyed by the conveying unit2A.

Along these lines, it is desirable to provide a slit vertically penetrating through the metal plate17. By providing this slit, a sudden, obvious change can be provided in a portion of the time-series data curve T. The time-series data curve T is thus formed as an even more distinctively characteristic curve. Therefore, since the slit is provided, the wireless tag reading device2can more surely distinguish the wireless tags attached to a commodity conveyed by the conveying unit2A from the other wireless tags (since time-series data for such other wireless tags will not have the distinct characteristics found in time-series data curve T). If the slit is provided, the length, the shape, and the like of the slit may be optimized according to an ambient signal environment.

The curve T1is a curve indicating ±20%, which is a threshold, with respect to the reference value. If a difference between a certain reference value and a value of ±20% with respect to the reference value is set to a fixed difference, the curve T1is a curve formed by connecting values obtained by adding or subtracting the fixed difference to or from reference values. Therefore, the curve T1is parallel to the curve T and is not a curve formed by connecting values of ±20% with respect to the reference values. A range surrounded by the curve T1is the first range. A curve T2is a curve indicating ±30%, which is a threshold, with respect to the reference value. Like the curve T1, the curve T2is parallel to the curve T. A range surrounded by the curve T2is the second range.

If the time-series data of the phase difference is included in the first range concerning the wireless tag attached to the commodity placed on the conveying belt9by the customer, the determining unit606determines that the time-series data satisfies the first condition and the wireless tag is conveyed by the conveying unit2A. If the time-series data of the phase difference is not included in the first range but is included in the second range concerning a certain wireless tag, the determining unit606determines that the time-series data satisfies the second condition. The determining unit606controls the touch panel81to output information concerning the commodity attached with the wireless tag. The touch panel81displays the information and a message that inquires the customer whether the customer intends to purchase the commodity. The first condition and the second condition are not limited to the above, and can be set as appropriate based on an ambient environment of the wireless tag reading device2. For example, the determining unit606may determine that the commodity is conveyed by the conveying unit2A if 80% or more of the time-series data is included in the first range.

The wireless tag reading device2may receive a response wave from a wireless tag other than the wireless tag attached to the commodity conveyed by the conveying unit2A. Concerning such a wireless tag, since the time-series data of the phase difference is not included in the first range and the second range, the wireless tag reading device determines that the commodity is not conveyed by the conveying unit2A. For example, if a response wave is received from a wireless tag attached to a commodity placed near the conveying unit2A, since this commodity is not being conveyed by the conveyance mechanism, it does not move, thus the phase difference is a fixed value once a detection error is excluded.

If the same wireless tag reading devices are provided adjacent to the wireless tag reading device2, the wireless tag reading device2may receive a response wave from a wireless tag conveyed by the adjacent wireless tag reading device. In such a case as this, the reading target wireless tag and the non-reading target wireless tag would be conveyed at approximately the same speed. However, since the distance between the antenna16and the non-reading target wireless tag is larger, time-series data of a phase difference concerning the non-reading target wireless tag will not be approximated by the curve T inFIG. 9. Therefore, even in such a case, the wireless tag reading device2can distinguish the reading target wireless tag from the other wireless tags.

If a plurality of wireless tag reading devices2are provided adjacent to one another, the shapes and the positions of the metal plates17of the wireless tag reading devices2can be varied from device to device. Consequently, it is possible to more surely distinguish the reading target wireless tag conveyed by a particular wireless tag reading device2from a wireless tag conveyed by another wireless tag reading device2. It is also possible to provide a plurality of antennas16.

If a plurality of antennas16are provided, accuracy for distinguishing the reading target wireless tag from the other wireless tags can be further improved. If a plurality of antennas16are provided, it is desirable to provide the plurality of antennas16arranged along the conveying direction. If the distances between the antennas16and the metal plate17are differentiated, the time-series data curves T of the respective antennas16are not approximate to each other and are distinguishable from one another. Therefore, the accuracy can be improved.

Processing concerning radio wave information, which is performed by the control unit20of the wireless tag reading device2, is explained with reference to the flowchart ofFIG. 10. The control unit20determines whether the start point sensors11detect a commodity, and a start notification is input to the first sensor input unit201(Act 1). If the start notification is input to the first sensor input unit201, the radio-wave control unit203outputs a transmission wave transmission instruction so that the antenna16transmits a transmission wave (Act 2). If the start notification is not input to the first sensor input unit201, the control unit20returns to Act 1.

Subsequently, when the antenna receives a response wave (Act 3), the radio-wave-information processing unit204stores radio wave information (Act 4). Thereafter, the control unit20determines whether a predetermined time has elapsed after the start notification was input (Act 5). If the predetermined time has elapsed, the radio-wave-information output unit205controls the communication interface50to transmit the radio wave information stored so far to the checkout device3(Act 6). If determining in Act 5 that the predetermined time has not elapsed, the control unit20returns to Act 2 and repeats the subsequent processing. The predetermined time is a time in which a commodity is conveyed in the section X. The predetermined time is determined depending on the conveying speed of the conveying unit2A. For example, the predetermined time is 14 seconds as illustrated inFIG. 9.

The antenna16may receive response waves from wireless tags other than the wireless tag attached to the commodity conveyed by the conveying unit2A. In such a case, the processing in Act 2 to Act 4 and Act 6 is performed in parallel for each of the wireless tags. The processing illustrated inFIG. 10is performed every time the commodity passes the start point sensors11. If a plurality of commodities are located in the section X, the processing is performed in parallel. Therefore, the radio-wave-information output unit205can control the communication interface50to transmit radio wave information for each of the wireless tags to the checkout device3.

Processing performed by the control unit60of the checkout device3is explained with reference to the flowchart ofFIG. 11. The control unit60determines whether the radio-wave-information acquiring unit601acquires radio wave information from the wireless tag reading device2(Act 11). If the radio wave information is acquired, the radio-wave-information acquiring unit601stores the received radio wave information (Act 12). If the radio-wave-information acquiring unit601does not acquire the radio wave information, the control unit60skips Act 12.

Thereafter, the control unit60determines whether a stop notification is input from the wireless tag reading device2to the second sensor input unit602(Act 13). If the end point sensors12of the conveying unit2A has not detected any commodity for a set time, the wireless tag reading device2determines that all purchase target commodities of the customer have been conveyed by the conveying unit2A, and inputs the stop notification to the second sensor input unit602. If the stop notification is input to the second sensor input unit602, the phase-difference calculating unit604calculates, based on phase information of transmission waves and response waves to the transmission waves in the stored radio wave information, for each of the transmission waves, a phase difference between the transmission wave and the response wave (Act14). Subsequently, the time-series data acquiring unit605stores, referring to individual article codes included in the radio wave information, for each of the individual article codes, the phase difference calculated in Act 14 (Act 15). That is, the time-series data acquiring unit605acquires, for each of the individual article codes, time-series data of a phase difference corresponding toFIG. 9.

Subsequently, the determining unit606determines whether the time-series data of the phase difference for each of the individual article codes is within the first range (Act 16). If the time-series data is within the first range, the determining unit606determines that the time-series data satisfies the first condition, and stores a commodity code concerning a commodity specified by the individual article code (Act 17). If determining in Act 16 that the time-series data of the phase difference is not within the first range, the determining unit606determines whether the time-series data of the phase difference is within the second range (Act 18). If the time-series data of the phase difference is within the second range, the determining unit606determines that the time-series data satisfies the second condition, and controls the touch panel to output a display instruction for information concerning a commodity specified by the individual article code (Act 19). The touch panel81shows a message that urges the customer to input whether the customer intends to purchase the commodity. If the determining unit606determines in Act 18 that the time-series data of the phase difference is not within the second range, the control unit60skips Act 17.

Subsequently, the determining unit606determines whether a purchase input is received by the touch panel81(Act 20). If determining in Act 20 that the purchase input is received, the determining unit606proceeds to Act 17 determining that the target commodity is conveyed by the conveying unit2A, and stores the commodity code. If the determining unit606determines in Act 20 that the purchase input is not received, the control unit60skips Act 17. Thereafter, the control unit60determines, concerning stored time-series data of phase differences of all the individual article codes, whether the determination by the determining unit606has ended (Act 21). If the determination by the determining unit606has ended, the payment process unit607performs the payment process concerning the commodity having the commodity code stored in Act 17 (Act 22), and the processing ends. If determining in Act 21 that the determination by the determining unit606has not ended concerning the time-series data of the phase difference of all the individual article codes, the control unit60returns to Act 16. The payment process is performed concerning the commodity conveyed by the conveying unit2A according to the processing explained above.

As explained above, the wireless tag reading device2includes the metal plate17that is provided along the conveying path9A and reflects a transmission wave transmitted from the antenna16. Additionally, the wireless tag reading device2includes the radio-wave information output unit205that outputs radio wave information relating to a phase difference between the transmission wave and a response wave. Accordingly, characteristic time-series data of a phase difference can be acquired for a wireless tag moving on the conveying path9A. Therefore, the checkout device3is capable of surely determining whether the conveyed wireless tag is a wireless tag attached to a commodity conveyed by the conveying path9A.

In the wireless tag reading device2, since the metal plate17is provided close to one side from the center in the conveying direction of the conveying path9A, the influence on the response wave by the metal plate17can be suppressed on the other side where the metal plate17is not located. Therefore, the wireless tag reading device can surely read tag information of a wireless tag on the other side.

If time-series data of a phase difference acquired by the time-series data acquiring unit605satisfies the first predetermined condition, the checkout device3processes tag information of a wireless tag relating to the time-series data. That is, if a difference between the time-series data and reference data is equal to or smaller than 20%, the checkout device3determines that a commodity attached with the wireless tag relating to the time-series data is conveyed by the conveying unit2A, and performs a payment process. The checkout device3does not perform the payment process for wireless tags other than the wireless tag. Therefore, the checkout device3can distinguish a target wireless tag conveyed by the conveying unit2A from non-target wireless tags other than the reading target wireless tag, and perform the payment process. Accordingly, it is possible to avoid performing a wrong payment process for commodities that a customer did not intend to purchase. Moreover, since the wireless tag reading device2uses a radio wave for reading commodity information from the wireless tag, it is possible to simplify a configuration for determining that the wireless tag is being (or has been) conveyed by the conveying unit2A.

If time-series data of a phase difference acquired by the time-series data acquiring unit605satisfies the second predetermined condition, the checkout device3outputs tag information of a wireless tag relating to the time series data. That is, if the time-series data satisfies the second condition, the checkout device3displays, on the touch panel81, commodity information of a commodity attached with the wireless tag relating to the time-series data, and asks the customer to input whether the customer intends to purchase the identified commodity corresponding to the wireless tag having time series data satisfying only the second condition. Therefore, if the determination about whether the wireless tag was conveyed by the conveying unit2A is doubtful, it is possible to ask the customer whether the commodity was conveyed by the conveying unit2A. Accordingly, it is possible to further avoid performing a wrong payment process.

In the embodiments described above, the tag information processing device is explained as the checkout device3. However, the tag information processing device can also be applied to, for example, a component managing device that conveys, with a conveying unit, any component attached to a wireless tag that identifies the component. In such a case, similarly, it is possible to distinguish the component being conveyed by the conveying unit from other components not conveyed by the conveying unit.

In the embodiments described above, the tag information processing device includes the first condition for determining whether a commodity is conveyed by the conveying unit2A and the second condition for displaying commodity information in order to confirm whether the customer intends to purchase the commodity. However, the tag information processing device in some examples may include just one of the first condition and the second condition. Further, in the embodiments described above, the phase-difference calculating unit604of the checkout device3calculates a phase difference. However, the wireless tag reading device2may calculate a phase difference and the time-series data acquiring unit605may acquire the phase difference.