Communication device

Abstract

To prevent a wireless tag not guaranteed to be positioned within a predetermined area from being read as a valid wireless tag.SOLUTION: A communication apparatus of an embodiment comprises an antenna, a reference tag, receiving means, and determining means. The receiving means uses the antenna to sequentially receive signals wirelessly transmitted from the reference tag whose position relative to the antenna is known and the tag to be read which is different from the reference tag. The determining means determines that the signal transmitted from the tag to be read and received by the receiving means is invalid based on the phase of the signal transmitted from the reference tag and received by the receiving means.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] Embodiments of the present invention relate to a communication device.

Background Art

[0002] For example, when identifying products placed in a shopping basket by wireless communication with a wireless tag attached to a product placed in the shopping basket, if wireless communication with a wireless tag not placed in the shopping basket is established, there is a risk of misidentifying the product to which the wireless tag is attached as the product placed in the shopping basket. Therefore, a technique has been devised in which while changing the relative position between an antenna and a wireless tag, the phase of a signal transmitted from the wireless tag is measured, and based on the phase difference, it is confirmed whether the wireless tag is located within a predetermined area.

[0003] However, since the phase of a signal transmitted from a wireless tag changes not only according to the distance between the wireless tag and the antenna but also according to the surrounding environment, there is a risk that it may not be possible to correctly determine whether the wireless tag is located within a predetermined area depending on various conditions. Under such circumstances, it has been desired to be able to prevent reading a wireless tag that is not guaranteed to be located within a predetermined area.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] The problem to be solved by the present invention is to provide a communication device capable of preventing reading a wireless tag not guaranteed to be located within a predetermined area as a valid wireless tag.

Means for Solving the Problem

[0006] The communication device according to the embodiment includes an antenna, a receiving means , decision means and invalid a determination means. The receiving means sequentially receives signals wirelessly transmitted from a reference tag whose relative position with respect to the antenna is known and a reading target tag different from the reference tag using the antenna. decision The means at two reading states where the separation distances between the antenna and the reference tag are different from each other respectively determines, based on the phase difference of the signal transmitted from the reference tag and received by the receiving means determine a threshold value. The invalidation determination means , by comparing the phase difference of the signals transmitted from the tag to be read and received by the receiving means at two reading states where the separation distances between the antenna and the tag to be read are different from each other respectively with the threshold value determined by the determination means whether the signal transmitted from the reading target tag and received by the receiving means is invalid.

Brief Description of the Drawings

[0007] [Figure 1] A diagram showing the configuration of a tag reader according to each embodiment. [Figure 2] A block diagram showing the main circuit configuration of the tag communication unit and the reading processing unit shown in FIG. 1. [Figure 3] A flowchart of the reading process in the first embodiment by the processor shown in FIG. 2. [Figure 4] A flowchart of the reading process in the first embodiment by the processor shown in FIG. 2. [Figure 5] A diagram schematically showing the configuration of one data record constituting a reading list. [Figure 6] A diagram for explaining the principle of determining whether the position of a target tag is within a placement area. [Figure 7] A flowchart of the reading process in the second embodiment by the processor shown in FIG. 2. [Figure 8] A diagram showing an example of an approximate curve representing the relationship between the antenna position and the phase. [Figure 9] A diagram showing an example of a phase change curve. [Figure 10] A diagram showing an example of a phase change curve. [Figure 11] A diagram showing an example of a phase change curve. [Figure 12] A diagram for explaining the characteristics of the phase change curve.

Best Mode for Carrying Out the Invention

[0008] Hereinafter, two embodiments will be described with reference to the drawings. In each embodiment, a tag reader configured to have functions as a communication device will be described as an example. Prior to the description of each embodiment, the configuration common to each embodiment will be described. FIG. 1 is a diagram showing the configuration of a tag reader 1 according to each embodiment. In FIG. 1, a part of the structure of the tag reader 1 is schematically shown. Also in FIG. 1, a part of the circuit configuration of the tag reader 1 is represented by a block diagram.

[0009] The tag reader 1 reads the tag data stored in a wireless tag (hereinafter referred to as a product tag) 2 attached to a product MEA and a wireless tag (hereinafter referred to as a reference tag) 3 attached to a table TAA, respectively. The product tag 2 is an example of a tag to be read. The tag reader 1 generates a product list representing a list of purchased products based on the read tag data and outputs it to a POS (point-of-sale) terminal 4. The tag reader 1 is typically used in a posture where the x-y plane in FIG. 1 is horizontal. Note that the table TAA may be one of the constituent members of the tag reader 1, or a table TAA different from the tag reader 1 may be arranged as shown in FIG. 1.

[0010] The wireless tag used as the product tag 2 or the reference tag 3 is also called an RFID (radio frequency identification) tag. The product tag 2 and the reference tag 3 are equipped with a memory and store pre-written tag data. The product tag 2 and the reference tag 3 wirelessly transmit the stored tag data while communicating with the tag reader 1 in a predetermined sequence. The tag data stored in the product tag 2 and the reference tag 3 includes a tag code as an identifier for identifying each of the product tag 2 and the reference tag 3. Further, the tag data stored in the product tag 2 includes a product code as an identifier for identifying the product MEA to which the product tag 2 is attached. The product code may be included as part of the tag code or may be separate from the tag code. The product code is, for example, a JAN (Japan article number) code.

[0011] On the upper surface of the table TAA, the product MEA is placed, for example, in a state of being accommodated in the basket BAA. The position where the basket BAA is placed on the table TAA is defined as the position shown in FIG. 1. Note that the product MEA may be placed directly on the table TAA, but in this case, the position where the product is placed is within the area occupied by the basket BAA placed at the defined position on the table TAA as shown in FIG. 1. Thus, the area where the product MEA is placed on the table TAA becomes the area occupied by the basket BAA placed at the defined position on the table TAA as shown in FIG. 1. Therefore, in the following, this area will be referred to as the placement area.

[0012] The reference tag 3 is embedded, for example, inside the table TAA. However, the method of attaching the reference tag 3 to the table TAA may be arbitrary, such as being attached to the upper surface or the lower surface of the table TAA. However, the reference tag 3 is attached to the table TAA so that its installation position does not change. The installation position of the reference tag 3 is near the boundary of the placement area as shown in FIG. 1.

[0013] The tag reader 1 includes an antenna 10, a moving mechanism 20, a tag communication unit 30, and a reading processing unit 40. Note that the lower side in FIG. 1 of the antenna 10 and the moving mechanism 20 represents the appearance with respect to the x-z plane, and the upper side represents the appearance with respect to the x-y plane. The antenna 10 radiates radio waves corresponding to the transmission high-frequency signal supplied from the tag communication unit 30. The antenna 10 receives the radio waves radiated from the product tag 2 and the reference tag 3, and outputs an electrical signal corresponding to this radio wave as a reception high-frequency signal. The antenna 10 is disposed below the table TAA and has the characteristic of being able to communicate with the product tag 2 and the reference tag 3 located in the reading space and the surrounding space respectively. The reading space is predefined, for example, as the space above the table TAA. It is assumed that the reading space is predefined, for example, as the space enclosing the basket BAA placed on the table TAA. Note that the reading space may be appropriately defined by, for example, the designer of the tag reader 1.

[0014] The moving mechanism 20 moves the antenna 10. The tag communication unit 30 executes communication processing for reading tag data. Based on the reading result in the tag communication unit 30, the reading processing unit 40 executes information processing for generating a product list, for example, as a list regarding the product MEA placed in the placement area in the state of being accommodated in the basket BAA.

[0015] The moving mechanism 20 includes a drive source 21, a rotating shaft 22, a rail 23, a stage 24, and a drive unit 25. The drive source 21 generates power for moving the antenna 10. The drive source 21 is, for example, a stepping motor. The rotating shaft 22 has a spiral groove formed on the side surface of an elongated cylindrical member. The rotating shaft 22 rotates about a straight line along the x-axis direction in FIG. 1 as the axis by the power generated by the drive source 21.

[0016] The rail 23 is formed with a spiral groove on the side surface of an elongated cylindrical member, which meshes with the spiral groove formed on the rotary shaft 22. One end of the rail 23 is arranged in a state where the formed spiral groove meshes with the spiral groove of the rotary shaft 22, and is supported by a support mechanism (not shown) so as to be rotatable about a straight line along the x-axis direction in FIG. 1 as an axis. The stage 24 has a through-hole formed with a spiral groove inside, and the rail 23 is arranged in a state of penetrating through this through-hole. The antenna 10 is fixed to the mounting surface formed on the upper side of the stage 24. The posture of the stage 24 is restricted by a guide rail (not shown) so as to maintain the state where the mounting surface faces upward. It is desirable that the upper surface of the stage 24 is maintained in a state that coincides with the x-y plane. For this reason, the stage 24 moves in the x-axis direction as the rail 23 rotates. Along with the movement of this stage 24, the antenna 10 is moved in the x-axis direction.

[0017] The drive unit 25 drives the drive source 21 so as to move the stage 24 from a predetermined starting point PA to an end point PB. The drive unit 25 monitors the position of the stage 24 and notifies the reading processing unit 40 of the reading position. Further, when the position of the stage 24 reaches the end point PB, the drive unit 25 notifies the reading processing unit 40 of the end of the movement. The drive unit 25 includes, for example, a home position sensor that detects a state where the stage 24 is located at the starting point PA, and monitors the position of the stage 24 based on the detection result of this home position sensor and the driving amount of the drive source 21. Alternatively, the drive unit 25 may include, for example, a sensor that detects the current position of the stage 24, and the method for such monitoring may be arbitrary, such as monitoring the position of the stage 24 based on the output of the sensor.

[0018] FIG. 2 is a block diagram showing the main circuit configuration of the tag communication unit 30 and the reading processing unit 40. Among the elements shown in FIG. 2, the same reference numerals are given to the elements also shown in FIG. 1. The tag communication unit 30 includes a baseband processor 31, a transmission unit 32, a duplexer 33, and a reception unit 34.

[0019] Under the instruction from the reading processing unit 40, the baseband processor 31 generates a transmission baseband signal for radiating radio waves from the antenna 10 to read tag data from each of the plurality of product tags 2 and reference tags 3 in a predetermined sequence, and supplies it to the transmission unit 32. The transmission unit 32 performs well-known processes such as modulation of a carrier wave using the transmission baseband signal supplied from the baseband processor 31 to obtain a transmission high-frequency signal, and supplies this transmission high-frequency signal to the duplexer 33. The duplexer 33 supplies the transmission high-frequency signal supplied from the transmission unit 32 to the antenna 10. The duplexer 33 supplies the reception high-frequency signal output from the antenna 10 to the reception unit 34.

[0020] The reception unit 34 performs well-known processes such as demodulation on the reception high-frequency signal supplied from the duplexer 33 to obtain a reception baseband signal, and supplies this reception baseband signal to the baseband processor 31. The reception unit 34 detects the phase of the radio wave received by the antenna 10 based on the reception high-frequency signal, and supplies phase information representing the phase to the baseband processor 31. That is, the reception unit 34 has a function as a receiving means. The baseband processor 31 attempts to extract tag data from the reception baseband signal supplied from the reception unit 34. If the baseband processor 31 can extract the tag data, it outputs the tag data to the reading processing unit 40. The baseband processor 31 outputs, to the reading processing unit 40, the phase information supplied from the reception unit 34 as detected from the reception baseband signal that is the extraction source of the tag data, together with the tag data.

[0021] The reading processing unit 40 includes a processor 41, a main memory 42, an auxiliary storage unit 43, an alarm unit 44, interface units 45, 46, 47, and a transmission path 48. The processor 41, the main memory 42, the auxiliary storage unit 43, the alarm unit 44, and the interface units 45, 46, 47 are communicable via the transmission path 48.

[0022] A computer for performing information processing is configured by connecting a processor 41, a main memory 42, and an auxiliary storage unit 43 via a transmission path 48. The processor 41 corresponds to the central part of the computer. The processor 41 executes various information processes according to information processing programs such as an operating system, middleware, and application programs. The information processing executed by the processor 41 includes the information processing described later for generating a product list.

[0023] The main memory 42 corresponds to the main storage part of the computer. The main memory 42 includes a non-volatile memory area and a volatile memory area. The main memory 42 stores an information processing program in the non-volatile memory area. Also, the main memory 42 may store data necessary for the processor 41 to execute processes for controlling each part in either the non-volatile or volatile memory area. The main memory 42 uses the volatile memory area as a work area where data is appropriately rewritten by the processor 41.

[0024] The auxiliary storage unit 43 corresponds to the auxiliary storage part of the computer. As the auxiliary storage unit 43, for example, well-known storage devices such as an electric erasable programmable read-only memory (EEPROM), a hard disc drive (HDD), and a solid state drive (SSD) can be used alone or in combination. The auxiliary storage unit 43 stores data used when the processor 41 performs various processes and data generated by the processes in the processor 41. The auxiliary storage unit 43 stores an information processing program. One of the information processing programs stored by the auxiliary storage unit 43 is an information processing program that describes the information processing for generating a product list. The warning unit 44 executes a warning operation for warning an operator of an abnormality. The warning unit 44 may appropriately include various well-known devices that execute arbitrary warning operations such as sounding, lighting, displaying, and voice reproduction.

[0025] The drive unit 25 is connected to the interface unit 45. The baseband processor 31 is connected to the interface unit 46. The POS terminal 4 is connected to the interface unit 47. The interface units 45, 46, and 47 interface the transfer of data between the drive unit 25, the baseband processor 31, or the POS terminal 4 and the processor 41. As the interface units 45, 46, and 47, for example, well-known interface devices for connecting peripheral devices to a computer device can be used. The transmission path 48 includes an address bus, a data bus, control signal lines, etc., and transmits data and control signals exchanged between the connected components.

[0026] The configurations described so far are common to the first embodiment and the second embodiment. Subsequently, the operations of the tag reader 1 in each of the first embodiment and the second embodiment will be described. Note that the content of the processing described below is an example, and changes in the order of some processing, omission of some processing, or addition of other processing are possible as appropriate.

[0027] [First Embodiment] The operator of the POS terminal 4 places the basket BAA containing the merchandise MEA that the customer wishes to purchase on the placement area on the table TAA, and then instructs the start of reading by a predetermined operation. Note that the operator of the POS terminal 4 can be either a store clerk or a customer. When such an operation for the instruction is performed, the POS terminal 4 requests the tag reader 1 to perform reading. The request from the POS terminal 4 is taken in by the reading processing unit 40 by the interface unit 47. Then, the processor 41 executes the reading process described below according to the information processing program stored in the main memory 42 or the auxiliary storage unit 43.

[0028] FIG. 3 and FIG. 4 are flowcharts of the reading process in the first embodiment by the processor 41. As ACT1, the processor 41 forms a first reading state. The first reading state is a state in which the stage 24 is positioned at a predetermined first reading position. The first reading position is assumed to be, for example, the starting point PA. However, the first reading position may be arbitrarily determined by, for example, the designer of the tag reader 1. Then, the processor 41 commands the drive unit 25 to set the position of the stage 24 as the first reading position. For example, the processor 41 sends a predetermined command signal for this command from the interface unit 45. When receiving this command, the drive unit 25 operates the drive source 21 to move the stage 24 to the first reading position. Note that if the reading position notified from the drive unit 25 matches the first reading position, the processor 41 does not have to issue a command to the drive unit 25.

[0029] As ACT2, the processor 41 commands the tag communication unit 30 to start reading the tag data of the wireless tag 2. For example, the processor 41 sends a predetermined command signal for the start reading command from the interface unit 45. In the tag communication unit 30, the baseband processor 31 receives the above command signal. Then, the baseband processor 31 outputs a transmission baseband signal to the transmission unit 32 and extracts tag data from the received baseband signal provided by the reception unit 34 in order to read tag data from all the wireless tags 2 that can communicate with each other according to a predetermined protocol. If the baseband processor 31 succeeds in extracting the tag data, it issues a reading notification to the reading processing unit 40. In this reading notification, the baseband processor 31 notifies the tag data and the phase information provided by the reception unit 34. Note that the protocol may be a well-known protocol such as a protocol compliant with ISO / IEC 18000. The baseband processor 31 performs a series of processes for reading tag data from all the wireless tags 2 that can communicate with each other once, or repeats the processes a plurality of times. How many times the baseband processor 31 performs the above series of processes in response to a single reading start command may be arbitrarily determined by, for example, the designer of the tag reader 1. Then, when the baseband processor 31 finishes the above series of processes a specified number of times, it issues a reading completion notification to the reading processing unit 40.

[0030] In the situation where tag data is being read as described above, the processor 41 transitions to the standby states of ACT3 and ACT4. As ACT3, the processor 41 checks whether a reading notification has been issued. If the processor 41 cannot confirm the corresponding event, it determines NO and proceeds to ACT4. As ACT4, the processor 41 checks whether a completion notification has been issued. If the processor 41 cannot confirm the corresponding event, it determines NO and returns to ACT3. Thus, in the standby states of ACT3 and ACT4, the processor 41 waits for a reading notification or a completion notification.

[0031] When the processor 41 receives, via the interface unit 46, the reading notification made by the baseband processor 31 as described above, it determines YES in ACT3 and proceeds to ACT5. As ACT5, the processor 41 updates the first reading list. The first reading list is list data representing the reading history of tag data in the first reading state. The first reading list is a set of data records each associated with each reading notification. When the processor 41 first executes ACT5 after starting the reading process, it generates a new data record and generates a new first reading list containing only this one data record. When the processor 41 executes ACT5 for the second time and later, it generates a new data record and updates the existing first reading list by adding this data record. Note that the first reading list is stored in the main memory 42 or the auxiliary storage unit 43.

[0032] FIG. 5 is a diagram schematically showing the configuration of one data record REA constituting the first reading list. The data record REA includes fields FAA, FAB, and FAC. The processor 41 sets the tag code included as the individual identifier of the wireless tag 2 in the tag data notified by the reading notification in the field FAA. The processor 41 sets the phase information notified by the reading notification in the field FAB. The processor 41 sets the position information representing the reading position notified from the driving unit 25 when the reading notification is made in the field FAC. The data record REA may not include the field FAC. Note that instead of the position information, the processor 41 may set the elapsed time from the time when the reading is started as ACT2 in the field FAC. In this case, the driving unit 25 may not notify the position information to the reading processing unit 40.

[0033] And if the processor 41 has finished updating the first reading list, it returns to the waiting states of ACT3 and ACT4. Thus, every time new tag data is read by the tag communication unit 30, the processor 41 records phase information and position information in association with the tag code included in the tag data. Then, when the processor 41 receives, via the interface unit 46, a completion notification made by the baseband processor 31 to notify the completion of reading, it determines YES in ACT4 and proceeds to ACT6. As ACT6, the processor 41 commands the tag communication unit 30 to stop reading. For example, the processor 41 sends out a predetermined command signal for the stop reading command from the interface unit 45. In the tag communication unit 30, the baseband processor 31 receives the above command signal. Then, the baseband processor 31 stops the above-described process for reading tag data. In this way, the processor 41 generates the first reading list as list data in which phase information and position information are recorded in association with the tag code included in the tag data read in the first reading state.

[0034] As ACT7, the processor 41 forms a second reading state. The second reading state is a state in which the stage 24 is located at a second reading position predetermined to be different from the first reading position. The second reading position is assumed to be, for example, the end point PB. However, the second reading position may be arbitrarily determined by, for example, the designer of the tag reader 1. However, the second reading position is determined such that the separation distance from the reference tag 3 is different from the separation distance between the first reading position and the reference tag 3. Then, for example, the processor 41 commands the drive unit 25 to set the position of the stage 24 to the second reading position. For example, the processor 41 sends out a predetermined command signal for this command from the interface unit 45. When receiving this command, the drive unit 25 operates the drive source 21 to move the stage 24 to the second reading position. Thus, the moving mechanism 20 corresponds to the moving means. As ACT8, the processor 41 commands the tag communication unit 30 to start reading the tag data of the wireless tag 2 in the same manner as ACT2. In response to this command, the tag communication unit 30 operates in the same manner as described above to read the tag data. When the tag communication unit 30 is reading the tag data, the processor 41 transitions to the waiting states of ACT9 and ACT10. In this waiting state, the processor 41 waits for a reading notification or a completion notification, similar to the waiting states of ACT3 and ACT4.

[0035] When the processor 41 receives a reading notification made by the baseband processor 31 via the interface unit 46, it determines YES in ACT9 and proceeds to ACT11. As ACT11, the processor 41 updates the second reading list. The second reading list is list data representing the history of reading tag data in the second reading state. The second reading list is list data having the same structure as the first reading list and is a set of data records REA shown in FIG. 4. When the processor 41 first executes ACT11 after starting the reading process, it generates a new data record and generates a new second reading list including only this one data record. When the processor 41 executes ACT11 for the second time and later, it generates a new data record and updates the existing second reading list by adding this data record. Note that the second reading list is stored in the main memory 42 or the auxiliary storage unit 43.

[0036] After the processor 41 finishes updating the second reading list, it returns to the waiting states of ACT9 and ACT10. Thus, each time the tag communication unit 30 reads new tag data, the processor 41 records the phase information and the position information in association with the tag code included in the tag data. When the processor 41 receives a completion notification made by the baseband processor 31 via the interface unit 46 to notify the completion of the reading, it determines YES in ACT10 and proceeds to ACT12. As ACT12, the processor 41 commands the tag communication unit 30 to stop reading in the same manner as ACT6. In the tag communication unit 30, the baseband processor 31 receives the above command signal. Then, the baseband processor 31 stops the above-described process for reading tag data. In this way, the processor 41 generates a second read list as list data in which phase information and position information are recorded in association with the tag code included in the tag data read in the second read state. After that, the processor 41 proceeds to ACT13 in FIG. 4.

[0037] As ACT13, the processor 41 determines a threshold value. The determination of this threshold value is performed, for example, as follows. The processor 41 searches each of the first read list and the second read list for a data record REA in which the tag code of the reference tag 3 is set in the field FAA. Then, the processor 41 sets the phase represented by the phase information set in the field FAB of the data record REA found from the first read list as the first phase. Also, the processor 41 sets the phase represented by the phase information set in the field FAB of the data record REA found from the second read list as the second phase. Further, the processor 41 obtains a phase difference as [first phase - second phase], and sets the phase difference as the threshold value. Note that the processor 41 may obtain a phase difference as [second phase - first phase] and set the phase difference as the threshold value.

[0038] As ACT14, the processor 41 checks whether the threshold value determined in ACT13 is appropriate. For example, the processor 41 checks whether the threshold value determined in ACT13 is within a predetermined allowable range. Here, since the reference tag 3 is attached to the table TAA so that its installation position does not change, the separation distance between the antenna 10 and the reference tag 3 is known in each of the first reading state and the second reading state. And when the radio wave radiated from the reference tag 3 reaches the antenna 10, the phase of the radio wave is determined according to the separation distance between the antenna 10 and the reference tag 3 if the environment is constant. However, the phase of the radio wave when it is radiated from the reference tag 3 and reaches the antenna 10 varies due to environmental changes. Therefore, based on the phase of the radio wave when it is radiated from the reference tag 3 and reaches the antenna 10 in a typical environment, an allowable range is predetermined as a phase range including this phase. The allowable range may be appropriately determined, for example, by the designer of the tag reader 1 or the like based on experiments, simulations, or rules of thumb. And if the threshold value determined in ACT13 is within the allowable range, the processor 41 determines YES, assuming that the threshold value is appropriate, and proceeds to ACT15.

[0039] As ACT15, the processor 41 selects one of the product tags 2 as the target tag. For example, the processor 41 selects one of the data records REA included in the first reading list, and when the tag code set in the field FAA of the data record REA is not the tag code of the reference tag 3, searches the second reading list for the data record REA in which the tag code is set in the field FAA. And if the corresponding data record REA is found, for example, the processor 41 sets the product tag 2 identified by the tag code as the target tag.

[0040] As ACT16, the processor 41 calculates the phase difference regarding the target tag. This phase difference The calculation is performed as follows, for example. The processor 41 sets the phase represented by the phase information set in the field FAB of the data record REA in which the tag code of the target tag is set in the field FAA among the data records REA included in the first read list as the first phase phase and to do. Further, for example, the processor 41 sets the phase represented by the phase information set in the field FAB of the data record REA in which the tag code of the target tag is set in the field FAA among the data records REA included in the second read list as the second phase phase and to do. Furthermore, the processor 41 obtains the phase difference as [the first phase - the second phase]. Note that the processor 41 may obtain the phase difference as [the second phase - the first phase].

[0041] As ACT17, the processor 41 checks whether the position of the target tag is within the placement area. For example, the processor 41 compares the phase difference calculated in ACT16 with a threshold value, and based on the result, determines whether the position of the target tag is within the placement area. For example, if the phase difference calculated in ACT16 by the processor 41 is less than the threshold value, it is determined as YES that it is within the placement area, and the process proceeds to ACT18.

[0042] FIG. 6 is a diagram for explaining the principle of determining whether the position of the target tag is within the placement area. In FIG. 6, the positions PAA and PAB are the positions of the antenna 10 in the first read state and the second read state, respectively. The positions PMA, PMB, PMC, and PMD are the positions of the four product tags 2, respectively. The position PR is the position of the reference tag 3.

[0043] The difference DIA between the distance DAA from the position PAA to the position PMA and the distance DAB from the position PAB to the position PMA, the difference DIB between the distance DAB from the position PAA to the position PMB and the distance DBB from the position PAB to the position PMB, and further the difference DIR between the distance DAR from the position PAA to the position PR and the distance DBR from the position PAB to the position PR satisfy the relationship DIB > DIR > DIA.

[0044] That is, the greater the separation distance of the product tag 2 and the reference tag 3 from the straight line LIA connecting the positions PAA and PAB, the smaller the difference in the separation distance from the antenna 10 when changing from the first reading state to the second reading state. Thus, the difference in separation distance DIB for the product tag 2 located at the position PMA outside the placement area in the y direction is greater than the difference in separation distance DIR for the reference tag 3. Also, the difference in separation distance DIB for the product tag 2 located at the position PMB inside the placement area in the y direction is greater than the difference in separation distance DIR for the reference tag 3. Therefore, based on the difference in separation distance DIR for the reference tag 3, it is possible to determine whether the position of the product tag 2 is within the placement area according to the difference in separation distance for the product tag 2.

[0045] Regarding the position PMD where the separation distance in the y direction from the straight line LIA is equal to that of the position PMA, the difference in separation distance is also equal to that of the position PMA. Also, regarding the position PMC where the separation distance in the y direction from the straight line LIA is equal to that of the position PMB, the difference in separation distance is also equal to that of the position PMB. Therefore, if the placement area is defined such that the center in the y direction of the placement area substantially coincides with the straight line LIA, the determination regarding the boundary of the placement area on the side where the reference tag 3 is not installed can also be performed in the same manner as above based on the difference in separation distance DIR for the reference tag 3.

[0046] And if there is no phase fluctuation due to environmental changes, the greater the difference in separation distance, the smaller the phase difference calculated by ACT13 and ACT16. For this reason, by the above processing in ACT17, it is possible to determine whether the position of the target tag is within the placement area. Thus, when the processor 41 executes the reading process based on the information processing program, the computer with the processor 41 as the central part functions as a confirmation means for confirming that the product tag 2 is located within the placement area as the reading area.

[0047] As ACT18, the processor 41 updates the product list. The product list is list data of products that the customer purchases. For example, when the processor 41 first executes ACT18 after starting the reading process, it generates a new product list that contains only one product code included in the tag code of the target tag or a product code that is pre-associated with the tag code of the target tag. When the processor 41 executes ACT18 for the second time or later, if the product code of the target tag is not included in the product list, it adds the product code to the product list, and if it is included, it increments the quantity of the product code by one. Note that the product list is stored in the main memory 42 or the auxiliary storage unit 43. The product list is list data regarding the product tag 2 that has been confirmed to be located within the placement area as the reading area. Thus, by the processor 41 executing the reading process based on the information processing program, the computer with the processor 41 as the central part functions as a generation means.

[0048] When the processor 41 finishes updating the product list, it proceeds to ACT19. For example, if the phase difference calculated in ACT16 is equal to or greater than the threshold value, the processor 41 determines that it is not within the placement area and proceeds to ACT19 by passing ACT18. That is, the processor 41 does not add to the product list for the product MEA to which the product tag 2 determined to be located outside the placement area is attached. At this time, the processor 41 discards the reading result from the target tag on the assumption that the signal received from the target tag is invalid. Thus, by the processor 41 executing the reading process based on the information processing program, the computer with the processor 41 as the central part functions as a determination means.

[0049] As ACT19, the processor 41 checks whether it has finished selecting all the product tags 2 that meet the condition for selection as the target tag in ACT15. Then, if there are still product tags 2 to be selected as the target tag, the processor 41 determines NO and repeats the processing after ACT15. However, at this time, in ACT15, the processor 41 selects a product tag 2 that has not yet been selected as the target tag. Thus, while sequentially using each of the product tags 2 from which tag data could be read in both the first reading state and the second reading state as the target tag, the processor 41 repeats the processing from ACT15 to ACT19.

[0050] Then, if the processor 41 has finished selecting each corresponding product tag 2 as the target tag, it determines YES, considering that the selection in ACT19 has ended, and proceeds to ACT20. As ACT20, the processor 41 notifies the product list to the POS terminal 4. Then, the processor 41 ends the reading process.

[0051] Incidentally, when a large environmental change occurs due to interference such as a large metal object being mixed in the reading space or its vicinity, the principle described with reference to FIG. 6 may not hold. When such an environmental change occurs, the phase difference calculated for the reference tag 3 with a known separation distance from the antenna 10, and thus the threshold value determined in ACT13, will deviate significantly from the logically assumed value. Therefore, for example, when the threshold value is outside the allowable range, the processor 41 determines NO, considering it inappropriate in ACT14, and proceeds to ACT21.

[0052] As ACT21, the processor 41 performs alarm processing. This alarm processing is for warning the operator or the like that there is a risk that product registration cannot be performed correctly. For example, the processor 41 causes the alarm unit 44 to perform an operation predetermined as an alarm operation for the above warning. Thus, by the processor 41 executing the reading process based on the information processing program, the computer having the processor 41 as the central part functions as an alarm means. And when a predetermined alarm cancellation condition is satisfied, the processor 41 terminates the alarm operation and then terminates the reading process. In this case, the processor 41 does not execute ACT15 to ACT20. The cancellation condition may be arbitrarily determined by the designer or user of the tag reader 1, for example, when it is notified from the POS terminal 4 that a predetermined cancellation operation has been performed on the POS terminal 4, or when the duration of the alarm operation exceeds a predetermined limit time.

[0053] As described above, the tag reader 1 of the first embodiment determines whether or not the indeterminate position of the product tag 2 is within the placement area by comparing the phase difference with respect to the reference tag 3 whose separation distance from the antenna 10 is known in both the first reading state and the second reading state, and the phase difference with respect to the product tag 2. Then, the tag reader 1 uses the tag code read from the product tag 2 determined to be located within the placement area as a valid tag code. Therefore, according to the tag reader 1, it is possible to prevent reading a product tag 2 that is not guaranteed to be located within the placement area as a valid product tag 2 while being able to communicate with a product tag 2 located outside the placement area.

[0054] Note that when the tag reader 1 of the first embodiment calculates a phase difference different from the phase difference calculated in a normal environment with respect to the reference tag 3 whose separation distance from the antenna 10 is known in either the first reading state or the second reading state, there is a risk that the environmental change fluctuates greatly and it is impossible to correctly determine whether or not it is within the above mounting area, or there is a risk that communication with the product tag 2 cannot be performed normally. Therefore, no product list is generated based on the reading result, and an alarm is issued. In such an environment, incorrect product registration will not occur. And based on the alarm, it is possible for the customer or the store clerk to take measures such as removing the cause of the disturbance, and it is possible to quickly perform product registration in a normal environment.

[0055] [Second Embodiment] In the second embodiment, what is different from the first embodiment is the reading process by the processor 41. FIG. 7 is a flowchart of the reading process in the second embodiment by the processor 41. As ACT31, the processor 41 instructs the tag communication unit 30 to start reading tag data. In response to this, the tag communication unit 30 starts the same operation as in the first embodiment.

[0056] As ACT32, the processor 41 instructs the moving mechanism 20 to start moving. For example, the processor 41 sends a predetermined command signal for the command to start moving from the interface unit 45. In the moving mechanism 20, the drive unit 25 receives the above command signal. Then, the drive unit 25 starts driving to rotate the drive source 21 in a predetermined forward rotation direction. The drive unit 25 monitors the position of the stage 24 based on the rotation amount of the drive source 21, and notifies the reading processing unit 40 of the position information representing this position. When the position of the stage 24 reaches the end point PB, the drive unit 25 stops the drive source 21. At this time, the drive unit 25 transmits a notification signal for completion notification to the reading processing unit 40. After that, the drive unit 25 starts driving to rotate the drive source 21 in the reverse rotation direction. When the position of the stage 24 reaches the start point PA, the drive unit 25 stops the drive source 21.

[0057] In the situation where tag data is being read while moving the antenna 10 as described above, the processor 41 transitions to the waiting states of ACT33 and ACT34. As ACT33, the processor 41 checks whether a read notification has been made. Then, if the processor 41 cannot confirm the corresponding event, it determines NO and proceeds to ACT34. As ACT34, the processor 41 checks whether a completion notification has been made. Then, if the processor 41 cannot confirm the corresponding event, it determines NO and returns to ACT33. Thus, in the waiting states of ACT33 and ACT34, the processor 41 waits for a read notification or a completion notification.

[0058] Then, when the read notification made by the baseband processor 31 as described in the first embodiment is received by the interface unit 46, the processor 41 determines YES at ACT33 and proceeds to ACT35. As ACT35, the processor 41 updates the read list. The read list may be the same as the first read list in the first embodiment. Then, if the processor 41 has finished updating the read list, it returns to the waiting states of ACT33 and ACT34. Thus, every time new tag data is read by the tag communication unit 30, the processor 41 records phase information and position information in association with the tag code included in the tag data. Then, when the notification signal for the completion notification transmitted from the drive unit 25 is received by the interface unit 45 because the position of stage 24 has reached the end point PB, the processor 41 determines YES at ACT34 and proceeds to ACT36.

[0059] As ACT36, the processor 41 issues a command to stop reading to the tag communication unit 30. In the tag communication unit 30, the baseband processor 31 receives the above command signal. Then, the baseband processor 31 stops the aforementioned process for reading tag data. In this way, while the stage 24 is being moved from the starting point PA to the ending point PB (hereinafter referred to as the reading period), the processor 41 generates a read list as list data in which phase information and position information are recorded in association with the tag code included in the tag data read during this period.

[0060] The driving of the drive source 21 by the driving unit 25 may be terminated in response to a stop instruction from the processor 41. In this case, for example, when the position of the stage 24 reaches the ending point PB, the driving unit 25 transmits a notification signal for completion notification to the reading processing unit 40 without terminating the driving by the driving unit 25. Then, if the processor 41 determines YES in ACT34 described later in response to this notification signal, prior to proceeding to ACT36, the processor 41 issues a movement stop command to the movement mechanism 20. Also in this case, as ACT34, the processor 41 may confirm whether or not the position of the stage 24 has reached the ending point PB based on the position information, and if it has reached the ending point PB, determine YES and issue a rotation stop command to the movement mechanism 20.

[0061] Here, the rotational speed of the drive source 21 is determined such that the time required to move the stage 24 from the starting point PA to the ending point PB is sufficiently longer than the time required to perform a series of processes for reading tag data from each of the wireless tags 2 once. Therefore, the baseband processor 31 repeatedly executes a series of processes for reading tag data from each of the product tags 2 and the reference tag 3 a plurality of times while the stage 24 is being moved from the starting point PA to the ending point PB.

[0062] Note that the longer the time required to move the stage 24 from the starting point PA to the ending point PB, the more times the tag data of one product tag 2 is read, and thus the accuracy of determining the phase change described later can be improved. However, the longer this time, the longer the execution time of the reading process, which may cause unreasonableness in store operations. Therefore, the rotational speed of the drive source 21 is appropriately determined by, for example, the designer of the tag reader 1 while taking the above circumstances into consideration.

[0063] As ACT37, the processor 41 determines a reference phase change. The reference phase change is a change in the phase when tag data is read from the reference tag 3, accompanying the position change of the antenna 10. For example, the processor 41 extracts all the data records REA in which the tag code of the reference tag 3 is set in the field FAA from the read list. The processor 41 obtains an approximate curve when plotting the intersections of the phase and position represented by the phase information and position information respectively set in the fields FAB and FAC of the extracted data record REA in a coordinate system with the vertical axis being the phase and the horizontal axis being the position of the antenna 10. The process for obtaining such an approximate curve is an example of regression analysis. Therefore, the processor 41 can use a well-known processing algorithm for regression analysis for the processing here.

[0064] FIG. 8 is a diagram showing an example of the approximate curve obtained as described above. In the horizontal axis direction in FIG. 8, the position corresponding to the midpoint between the start point PA and the end point PB is taken as the reference position "0", and the separation distance in the x-axis direction from the reference position is represented by a negative value for the start point PA side and a positive value for the end point PB side respectively. Here, since the phase represented by the phase information is a value from 0 degrees to 360 degrees, there are places where the value jumps from 0 degrees to 360 degrees or from 360 degrees to 0 degrees. Therefore, the processor 41 gives an offset of +360 degrees or -360 degrees at the places where the phase changes beyond a first threshold value defined as a value slightly smaller than 360 degrees, such as 350 degrees, to connect the places where the value jumps from 0 degrees to 360 degrees and from 360 degrees to 0 degrees respectively, and obtains a curve (hereinafter referred to as a phase change curve).

[0065] FIG. 9 is a diagram showing an example of the phase change curve obtained from the curve shown in FIG. 8. Then, the processor 41 sets the phase change represented by the phase change curve obtained as shown in FIG. 9 as the reference phase change. Note that FIG. 9 shows a phase change curve when a wireless tag exists at a position where the x coordinate coincides with the midpoint between the start point PA and the end point PB. The x coordinate of the position of the reference tag 3 shown in FIG. 1 is different from the x coordinate of the midpoint between the start point PA and the end point PB. Therefore, the actually obtained phase change curve for the reference tag 3 is different from FIG. 9.

[0066] FIGS. 10 and 11 are diagrams showing different phase change curves respectively. FIGS. 10 and 11 show examples of phase change curves obtained for wireless tags at positions different from the position of the wireless tag with respect to the phase change curve shown in FIG. 9. For a wireless tag whose y coordinate is approximately the same as the position of the wireless tag with respect to the phase change curve shown in FIG. 9 and whose x coordinate is about 100 mm closer to the end point PB side, for example, a phase change curve as shown in FIG. 10 can be obtained. For a wireless tag whose x coordinate is approximately the same as the position of the wireless tag with respect to the phase change curve shown in FIG. 9 and whose separation distance from the straight line connecting the start point PA and the end point PB is larger, for example, a phase change curve as shown in FIG. 11 can be obtained. In this way, a phase change curve having characteristics according to the position of the wireless tag is obtained.

[0067] As ACT38 in FIG. 7, the processor 41 checks whether the reference phase change determined in ACT37 is appropriate. If there is no large environmental change due to disturbance as described in the first embodiment, the characteristics of the reference phase change will be close to known characteristics. Note that the characteristics of the reference phase change can be captured, for example, as the vertex position, continuity, smoothness, or the presence or absence of concavity or convexity in the phase change curve.

[0068] The processor 41, for example, divides the distance from the start point PA to the end point PB into a plurality of sections, and obtains the minimum value and the maximum value within each section of the values shown by the phase change curve. Then, when the difference between the maximum value and the minimum value obtained within the same section is larger than a predetermined second threshold value, the processor 41 determines that the reference phase change is not continuous and smooth and is not appropriate.

[0069] For example, for each of the above intervals, the processor 41 obtains the average value of the values indicated by the phase change curve within that interval, obtains the difference from the average value of the adjacent interval in a certain direction of that interval, and counts the number of concave and convex portions as the number of locations where the sign of the difference changes (hereinafter referred to as sign change points). Then, when the number of concave and convex portions is greater than a predetermined third threshold value, the processor 41 determines that the reference phase change is not appropriate due to the presence of concavities and convexities.

[0070] For example, when the above sign change points are localized only within one or a plurality of predetermined consecutive intervals, the processor 41 determines that location as the vertex position. And when the vertex position deviates from a predetermined allowable range including the position determined according to the position of the reference tag 3, the processor 41 determines that the vertex position is not appropriate and not valid.

[0071] Note that the sign change point originally occurs only for one location of the antenna position where the separation distance between the reference tag 3 and the antenna 10 is minimized, and is originally "1". Therefore, in principle, the third threshold value is set to, for example, "1", and the processor 41 may determine that it is not valid if the number of concave and convex portions is greater than or equal to the third threshold value. However, due to the influence of phase measurement errors and the like, there may be a plurality of additional sign change points in the vicinity of the sign change regarding the above antenna position. Therefore, it is preferable to set the third threshold value to an appropriate value of 2 or more so as to ignore these sign change points. The first threshold value, the second threshold value, and the third threshold value may be arbitrarily determined by, for example, the designer of the tag reader 1 based on experiments, simulations, or rules of thumb.

[0072] And if none of the application conditions predetermined as at least any one of the above plurality of determinations are satisfied, the processor 41 determines that it is valid as YES and proceeds to ACT39. As ACT39, the processor 41 selects one of the product tags 2 as the target tag. For example, the processor 41 selects one of the data records REA included in the reading list, and sets the product tag 2 identified by the tag code as the target tag when the tag code set in the field FAA of the data record REA is not the tag code of the reference tag 3. As ACT40, the processor 41 determines the phase change regarding the target tag. For example, similar to ACT37, the processor 41 obtains a phase change curve regarding the phase recorded in the reading list for the target tag, and determines the phase change of the target tag as the phase change represented by the phase change curve.

[0073] As ACT41, the processor 41 checks whether the target tag is located within the reading area by comparing the phase change determined in ACT40 with the reference phase change determined in ACT37. When a vertex appears in the phase change curve obtained in ACT40, the smoothness of the phase change curve can be evaluated based on the average value of an interval that is a certain interval away from the interval including this vertex. And the smaller the corresponding average value is, that is, the smoother the phase change curve is, the greater the separation distance of the target tag in the direction perpendicular to the moving trajectory of the antenna 10 will be. In this embodiment, if the separation distance of the target tag in the direction perpendicular to the moving trajectory of the antenna 10 is smaller than the separation distance of the reference tag 3 in the direction perpendicular to the moving trajectory of the antenna 10, the target tag is located within the reading area. Therefore, for example, if the above average value is less than or equal to the average value of a similar interval regarding the phase change curve obtained in ACT37 for the reference tag 3, the processor 41 determines that the target tag is located within the reading area. And if the processor 41 can determine that the target tag is located within the reading area, it determines YES in ACT41 and proceeds to ACT42.

[0074] FIG. 12 shows an example of an approximation curve when the absolute value of the above difference is plotted with the vertical axis representing the absolute value of the difference and the horizontal axis representing the interval number. The interval number is a number assigned to each of a plurality of intervals so as to increase in order from the start point PA side, for example. In FIG. 12, the curve represented by the solid line and the curve represented by the broken line relate to different wireless tags, respectively. In the curves shown in FIG. 12, the absolute value becomes 0 in the interval including the position where the vertex appears in the phase change curve. That is, FIG. 12 is an example in the case where the x coordinate of the position of the wireless tag corresponding to the curve represented by the solid line is closer to the start point PA side than the x coordinate of the position of the wireless tag corresponding to the curve represented by the broken line. Also, since the curve represented by the broken line is smoother than the curve represented by the solid line in FIG. 12, the y coordinate of the position of the wireless tag corresponding to the curve represented by the solid line is closer to the y coordinates of the start point PA and the end point PB than the y coordinate of the position of the wireless tag corresponding to the curve represented by the broken line.

[0075] As ACT42, the processor 41 updates the product list. For example, when the processor 41 first executes ACT42 after starting the reading process, it generates a new product list including only one product code included in the tag code of the target tag or a product code previously associated with the tag code of the target tag. When the processor 41 executes ACT41 for the second time and subsequent times, if the product code of the target tag is not included in the product list, it adds the product code to the product list, and if it is included, it increases the quantity of the product code by one. The product list is stored in the main memory 42 or the auxiliary storage unit 43.

[0076] If the processor 41 has finished updating the product list, it proceeds to ACT43. If the processor 41 is not below the average value of the similar section regarding the phase change curve obtained in ACT37 for the reference tag 3, it determines NO at ACT41 assuming that the target tag is not located within the reading area, passes through ACT42, and proceeds to ACT43. That is, the processor 41 does not add to the product list a product MEA to which the wireless tag 2 located outside the area is attached. At this time, the processor 41 discards the reading result from the target tag assuming that the signal received from the target tag is invalid. Thus, by the processor 41 executing the reading process based on the information processing program, the computer with the processor 41 as the central part functions as a determination means based on regression analysis.

[0077] In addition, if the x coordinate of the position of the product tag 2 is within the range from the x coordinate of the start point PA to the x coordinate of the end point PB, a vertex appears in the phase change curve obtained in ACT40. However, if the x coordinate of the position of the product tag 2 is outside the above range, there is no vertex in the phase change curve. In the present embodiment, as shown in FIG. 1, the position where the x coordinate is out of the range from the x coordinate of the start point PA to the x coordinate of the end point PB is not the position inside the basket BAA. Therefore, for example, the processor 41 may determine that the target tag is located outside the reading area even when there is no vertex in the phase change curve. When this determination is made by the processor 41, the x coordinates of the start point PA and the end point PB may be set near the x coordinate of the boundary of the reading area.

[0078] As ACT43, the processor 41 checks whether it has finished selecting all of the wireless tags 2 from which tag data could be read during the reading period as target tags. Then, if there are still wireless tags 2 to be selected as target tags, the processor 41 determines NO and repeats the processing from ACT39. However, in this case, in ACT39, the processor 41 selects a wireless tag 2 that has not yet been selected as a target tag. As a result, the processor 41 repeats the processing of ACT39 to ACT43 while sequentially using each of the wireless tags 2 from which tag data could be read during the reading period as a target tag.

[0079] Then, if the processor 41 has finished selecting each of the wireless tags 2 from which tag data could be read during the reading period as a target tag, it determines YES in ACT43 and proceeds to ACT44. As ACT44, the processor 41 notifies the POS terminal 4 of the product list. Then, the processor 41 ends the reading process.

[0080] Incidentally, if a large environmental change occurs due to interference and there is a large change in the characteristics of the phase change curve required in ACT37, the processor 41 checks that any of the application conditions in ACT38 described above are satisfied, determines NO in ACT38, and proceeds to ACT45. As ACT45, the processor 41 performs alarm processing in the same manner as ACT21 in FIG. 4. Then, if the processor 41 has finished the alarm processing, it ends the reading process. In this case, the processor 41 does not execute ACT39 to ACT44.

[0081] As described above, the tag reader 1 of the second embodiment determines whether the position of the product tag 2 is within the placement area by comparing the phase change related to the reference tag 3 and the phase change related to the product tag 2 when the product tag 2 and the reference tag 3 are read multiple times while moving the antenna 10. Then, the tag reader 1 uses the tag code read from the product tag 2 determined to be located within the placement area as a valid tag code. Therefore, according to the tag reader 1, it is possible to prevent reading a product tag 2 that is not guaranteed to be located within the placement area as a valid product tag 2 while being able to communicate with a product tag 2 located outside the placement area.

[0082] Also, in the tag reader 1 of the second embodiment, when a phase change different from the phase change that occurs in a normal environment is required for the reference tag 3 for which the change in the separation distance from the antenna 10 accompanying the movement of the antenna 10 is known, there is a risk that the environmental change fluctuates greatly and the determination as to whether it is within the above-described placement area cannot be made correctly, or there is a risk that communication with the product tag 2 cannot be performed normally. Therefore, no product list is generated based on the reading result, and an alarm is issued. Incorrect product registration in such an environment can be avoided. Based on the alarm, it is possible for the customer or the store clerk to take measures such as removing the cause of the disturbance, and it is possible to promptly perform product registration in a normal environment.

[0083] The following various modifications are possible for this embodiment. In each embodiment, the method of using the determination result as to whether it is within the placement area may be arbitrary. For example, the tag reader 1 may output the tag data read only when it can be determined that it is within the placement area without creating a product list. Or, for example, the tag reader 1 may generate list data that represents each of the read tag data and associates information representing the determination result as to whether it is within the placement area with each tag data. Or, for example, it is also conceivable to use it as a device that determines whether a wireless tag 2 identified by a specified tag code exists within the placement area.

[0084] Instead of moving the antenna 10, the table TAA may be moved. Alternatively, both the antenna 10 and the table TAA may be moved.

[0085] A plurality of reference tags 3 may be provided at different positions respectively, and based on the determination results performed as in each of the above embodiments with respect to each of these plurality of reference tags 3, the final determination of abnormality and inside / outside the region may be made.

[0086] The attachment method of the reference tag 3 may be arbitrary. For example, the reference tag 3 may be attached to the basket BAA. Alternatively, for example, the reference tag 3 may be attached to a constituent member of the tag reader 1 not shown in FIG. 1, or a support member attached to these constituent members or the table TAA. Furthermore, different from the constituent members of the tag reader 1, the reference tag 3 may be attached to a member disposed in the vicinity of the tag reader 1, or a support member attached to that member.

[0087] The tag to be read is not limited to the product tag 2 attached to the product MEA, and may be attached to any object other than the product MEA.

[0088] Each function realized by the processor 41 through information processing may also be realized in part or in whole by hardware that executes information processing not based on a program such as a logic circuit. Also, each of the above functions may be realized by combining software control with hardware such as the above logic circuit.

[0089] Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the gist of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are also included in the invention described in the claims and its equivalent scope. The invention described in the original claims of the present application is appended below. [Appendix 1] An antenna and receiving means for sequentially receiving signals wirelessly transmitted from a reference tag whose relative position with respect to the antenna is known and a tag to be read different from the reference tag using the antenna determination means for determining, based on the phase of the signal transmitted from the reference tag and received by the receiving means, that the signal transmitted from the tag to be read and received by the receiving means is invalid A communication device comprising the above. [Appendix 2] An antenna and receiving means for sequentially receiving signals wirelessly transmitted from a reference tag whose relative position with respect to the antenna is known and a tag to be read different from the reference tag using the antenna determination means for determining, based on a regression analysis of the phases of the signals transmitted from the reference tag in a plurality of states where the distances between the antenna and the reference tag are different from each other and received by the receiving means, that the signal transmitted from the tag to be read and received by the receiving means is invalid A communication device comprising the above. [Appendix 3] Moving means for moving at least one of the antenna and the reference tag to form a plurality of states where the distances between the antenna and the reference tag are different from each other The communication device according to Appendix 2, further comprising the above. [Appendix 4] Alarm means for alarming as an abnormal reading when determined to be invalid by the determination means The communication device according to any one of Appendices 1 - 3, further comprising the above. [Appendix 5] An antenna and receiving means for sequentially receiving signals wirelessly transmitted from a reference tag whose relative position with respect to the antenna is known and a tag to be read different from the reference tag using the antenna Confirmation means for confirming that the tag to be read is located within a predetermined reading area based on the phase of the signal transmitted from the reference tag and received by the receiving means and the phase of the signal transmitted from the tag to be read and received by the receiving means; Generation means for generating list data regarding the corresponding tag to be read based on the signal transmitted from the tag to be read and confirmed to be located within the reading area by the confirmation means and received by the receiving means; A communication device comprising the above. [Appendix 6] Judgment means for judging that the signal transmitted from the tag to be read and received by the receiving means is invalid based on the phase of the signal transmitted from the reference tag and received by the receiving means; Further comprising: When the generation means is judged to be invalid by the judgment means, the generation means does not generate the list data. The communication device according to Appendix 5. [Appendix 7] An antenna; Receiving means for sequentially receiving signals wirelessly transmitted from a reference tag whose relative position with respect to the antenna is known and a tag to be read different from the reference tag using the antenna; Based on the regression analysis result regarding the phase of the signals respectively transmitted from the reference tag in a plurality of states where the distances between the antenna and the reference tag are different from each other and received by the receiving means, and the regression analysis result regarding the phase of the signals respectively transmitted from the tag to be read in a plurality of states where the distances between the antenna and the tag to be read are different from each other and received by the receiving means, confirmation means for confirming that the tag to be read is located within a predetermined reading area; Generation means for generating list data regarding the corresponding tag to be read based on the signal transmitted from the tag to be read and confirmed to be located within the reading area by the confirmation means and received by the receiving means; A communication device comprising the above. [Appendix 8] Judgment means for judging that the signal transmitted from the tag to be read and received by the receiving means is invalid based on the regression analysis regarding the phase of the signals respectively transmitted from the reference tag in a plurality of states where the distances between the antenna and the reference tag are different from each other and received by the receiving means; Further comprising: When the generation means is judged to be invalid by the judgment means, the generation means does not generate the list data. The communication device according to Appendix 7. [Appendix 9] Moving means for moving at least one of the antenna and the reference tag so as to form a plurality of states in which the distances between the antenna and the reference tag are different from each other, The communication device according to Appendix 7 or Appendix 8, further comprising the above.

Description of Symbols

[0090] 1…Tag reader, 2…Product tag (wireless tag), 3…Reference tag (wireless tag), 4…POS terminal, 10…Antenna, 20…Moving mechanism, 21…Drive source, 22…Rotating shaft, 23…Rail, 24…Stage, 25…Drive unit, 30…Tag communication unit, 31…Baseband processor, 32…Transmitter, 33…Multiplexer, 34…Receiver, 40…Reading processing unit, 41…Processor, 42…Main memory, 43…Auxiliary storage unit, 44…Alarm unit, 45…Interface unit, 46…Interface unit, 47…Interface unit, 48…Transmission path.

Claims

1. An antenna, receiving means for sequentially receiving signals wirelessly transmitted from a reference tag whose relative position with respect to the antenna is known and a reading target tag different from the reference tag using the antenna; determining means for determining a threshold value based on a phase difference of signals transmitted from the reference tag and received by the receiving means in two reading states where the separation distances between the antenna and the reference tag are different from each other; invalidation determination means for determining that the signal transmitted from the reading target tag and received by the receiving means is invalid by comparing the phase difference of the signals transmitted from the reading target tag and received by the receiving means in two reading states where the separation distances between the antenna and the reading target tag are different from each other with the threshold value determined by the determining means; A communication device comprising:

2. Alarm means for alarming as an abnormal reading when the threshold value determined by the determining means deviates from an allowable range, The communication device according to claim 1, further comprising:

3. An antenna, receiving means for sequentially receiving signals wirelessly transmitted from a reference tag whose relative position with respect to the antenna is known and a reading target tag different from the reference tag using the antenna; first change determination means for determining a change in the phase of the signal received by the receiving means as the distance between the antenna and the reference tag changes by performing a regression analysis on the phases of the signals transmitted from the reference tag and received by the receiving means in a plurality of states where the distances between the antenna and the reference tag are different from each other; second change determination means for determining a change in the phase of the signal received by the receiving means as the distance between the antenna and the reading target tag changes by performing a regression analysis on the phases of the signals transmitted from the reading target tag and received by the receiving means while varying the distances between the antenna and the reading target tag; Invalidation determination means for determining that the signal transmitted from the tag to be read and received by the receiving means is invalid by comparing the phase change determined by the second change determination means with the phase change determined by the first change determination means; A communication device comprising the same. **Claim 4** Alarm means for alarming an abnormality in reading when the feature of the phase change determined by the first change determination means is different from a predetermined feature; The communication device according to claim 3, further comprising the same. **Claim 5** An antenna; Receiving means for sequentially receiving signals wirelessly transmitted from a reference tag whose relative position with respect to the antenna is known and a tag to be read different from the reference tag using the antenna; Determination means for determining a threshold value based on the phase difference between the signals transmitted from the reference tag and received by the receiving means in two reading states where the separation distances between the antenna and the reference tag are different from each other; Confirmation means for confirming that the tag to be read is located within a predetermined reading area by comparing the phase difference between the signals transmitted from the tag to be read and received by the receiving means in two reading states where the separation distances between the antenna and the tag to be read are different from each other with the threshold value determined by the determination means; Generation means for generating list data regarding the corresponding tag to be read based on the signal transmitted from the tag to be read confirmed to be located within the reading area by the confirmation means and received by the receiving means; A communication device comprising the same. **Claim 6** The generation means does not generate the list data when the threshold value determined by the determination means is out of an allowable range. The communication device according to claim 5. **Claim 7** An antenna; Receiving means for sequentially receiving signals wirelessly transmitted from a reference tag whose relative position to the antenna is known and a read target tag different from the reference tag, using the antenna; First change determination means for determining a change in the phase of the signal received by the receiving means as the distance between the antenna and the reference tag changes, by performing a regression analysis on the phases of the signals transmitted from the reference tag in a plurality of states where the distances between the antenna and the reference tag are different from each other and received by the receiving means; Second change determination means for determining a change in the phase of the signal received by the receiving means as the distance between the antenna and the read target tag changes, by performing a regression analysis on the phases of the signals transmitted from the read target tag while varying the distances between the antenna and the read target tag and received by the receiving means; Confirmation means for confirming that the read target tag is located within a predetermined reading area by comparing the phase change determined by the second change determination means with the phase change determined by the first change determination means; Generation means for generating list data regarding the corresponding read target tag based on the signal transmitted from the read target tag confirmed to be located within the reading area by the confirmation means and received by the receiving means; A communication device comprising:

8. The generation means does not generate the list data when the feature of the phase change determined by the first change determination means is different from a predetermined feature. The communication device according to claim 7.

Images