Wireless tag communication device

Abstract

To provide a wireless tag communication device capable of quickly reading information from a wireless tag.SOLUTION: A wireless tag communication device according to an embodiment comprises multiple antennas, a reading device, and a driving device. The multiple antennas are provided on a lower side of a table for placing thereon an article with a wireless tag attached thereto. The reading device communicates with a wireless tag via the antennas to read information from the wireless tag in a placement area on the table for placing an article thereon. The driving device moves the multiple antennas such that a trajectory of the multiple antennas as a whole is collaboratively drawn by the multiple antennas.SELECTED DRAWING: Figure 3

Description

[Technical Field]

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

[0002] In recent years, wireless tags have increasingly been used to carry out accounting procedures instead of the bar codes that have been used up until now.

[0003] In such a system, a wireless tag is attached to an item, and a wireless tag communication device detects the wireless tag and reads information from it. When the wireless tag is irradiated with electromagnetic waves, it transmits electromagnetic waves in response. The wireless tag communication device detects the wireless tag and reads information from it by moving an antenna that emits electromagnetic waves and receiving the electromagnetic waves transmitted from the wireless tag in response. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2019-219284 [Patent Document 2] Japanese Patent Publication No. 2023-035625 Summary of the Invention [Problem to be solved by the invention]

[0005] It is desirable for a radio tag communication device to be able to read information from a radio tag in a short time.

[0006] The problem to be solved by the present invention is to provide a radio tag communication device that can read information from a radio tag in a short time. [Means for solving the problem]

[0007] The RFID tag communication device according to the embodiment includes multiple antennas, a reader, and a drive unit. The multiple antennas are arranged below a table on which RFID-tagged articles are placed. The reader communicates with the RFID tags via the antennas and reads information from the RFID tags within a placement range on the table on which the articles are placed. The drive unit moves the multiple antennas so that the multiple antennas share the overall trajectory of the multiple antennas. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a block diagram showing an example of the configuration of a radio tag communication device according to an embodiment. [Figure 2] FIG. 2 is a block diagram showing an example of the configuration of the reading device shown in FIG. [Figure 3] FIG. 3 is a side view schematically showing an example of the configuration of the radio tag communication device according to the first embodiment. [Figure 4] FIG. 4 is a plan view schematically illustrating an example of the configuration of the radio tag communication device according to the first embodiment. [Figure 5] FIG. 5 is a plan view schematically showing an example of the configuration of a device for communicating with a radio tag according to a first modified example of the first embodiment. [Figure 6] FIG. 6 is a plan view schematically showing an example of the configuration of a radio tag communication device according to a second modified example of the first embodiment. [Figure 7] FIG. 7 is a side view schematically showing an example of the configuration of a radio tag communication device according to the second embodiment. [Figure 8] FIG. 8 is a side view schematically showing an example of the configuration of a radio tag communication device according to the third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments will be described with reference to the drawings. The scale of each part in each drawing referred to in the description of the embodiments may be changed as appropriate. Furthermore, for the sake of explanation, each drawing may omit some components.

[0010] (Radio tag communication device) First, a radio tag communication device 10 according to an embodiment will be described with reference to Fig. 1. Fig. 1 is a block diagram showing an example of the configuration of a radio tag communication device 10 according to an embodiment.

[0011] The wireless tag communication device 10 determines whether a wireless tag 520 attached to an item 510 such as a commodity is within a predetermined range, reads information from the wireless tag 520 for the wireless tag 520 within the predetermined range, and processes the read information.

[0012] 1 shows one item 510 and one wireless tag 520 for convenience, but this does not mean that there are any particular number of items 510 and wireless tags 520. The number of items 510 and wireless tags 520 may be one or more, and is generally more than one. One wireless tag 520 is attached to one item 510.

[0013] The RFID tag communication device 10 includes a reader 100, a driving device 200, an antenna 300, and a terminal 400.

[0014] The reader 100 controls the driving device 200 and the antenna 300 to read information from the wireless tag 520. An example of the configuration of the reader 100 will be described later.

[0015] The driving device 200 is a device that moves the antenna 300. An example of the configuration of the driving device 200 will be described later.

[0016] The antenna 300 is a device for communicating with the wireless tag 520. The antenna 300 emits electromagnetic waves. The antenna 300 also receives electromagnetic waves transmitted from the wireless tag 520 in response to the electromagnetic wave emission. The antenna 300 converts the radio waves received from the wireless tag 520 into high-frequency signals and outputs the high-frequency signals to the reader 100.

[0017] The terminal 400 is a device that processes information read from the wireless tag 520 by the reader 100. The terminal 400 is a personal computer (PC) or the like, but is not limited to this and may be any device that processes information.

[0018] The wireless tag 520 is typically an RFID (radio frequency identification) tag. The wireless tag 520 may be another type of wireless tag. The wireless tag 520 is a passive wireless tag that operates using a predetermined radio wave emitted from the antenna 300 as its energy source. The wireless tag 520 emits a signal including information stored in the wireless tag 520 by performing backscatter modulation on an unmodulated signal. For example, the information stored in the wireless tag 520 includes identification information that allows unique identification. For example, the information stored in the wireless tag 520 includes information about the item 510 to which the wireless tag 520 is attached.

[0019] (Reading device) Next, the reading device 100 will be described with reference to Fig. 2. Fig. 2 is a block diagram showing an example of the configuration of the reading device 100.

[0020] The reading device 100 includes a processor 101, a ROM (read-only memory) 102, a RAM (random-access memory) 103, a first connection interface 104, a second connection interface 105, a high-frequency front-end unit 106, a digital amplitude modulation unit 107, a DA (digital to analog) conversion unit 108, an AD (analog to digital) conversion unit 109, a demodulation unit 110, and a storage device 111. The units included in the reading device 100 can communicate with each other via a bus 112.

[0021] The processor 101 corresponds to the central part of a computer that performs processing such as calculations and controls required for the operation of the reading device 100. The processor 101 loads various programs stored in the ROM 102 or the storage device 111 into the RAM 103. The processor 101 executes the programs loaded into the RAM 103 to perform various functions required for the operation of the reading device 100.

[0022] The processor 101 is a central processing unit (CPU), a micro processing unit (MPU), a system on a chip (SoC), a digital signal processor (DSP), a graphics processing unit (GPU), an application specific integrated circuit (ASIC), a programmable logic device (PLD), a field-programmable gate array (FPGA), etc. The processor 101 may be a combination of two or more of these.

[0023] The ROM 102 corresponds to the main memory of a computer centered around the processor 101. The ROM 102 is a non-volatile memory used exclusively for reading data. The ROM 102 stores programs that cause the processor 101 to execute various functions. The ROM 102 also stores data and various setting values ​​used by the processor 101 when it performs various processes.

[0024] The RAM 103 corresponds to the main memory device of a computer centered around the processor 101. The RAM 103 is a memory used for reading and writing data. The RAM 103 is a work area that stores data that is temporarily used when the processor 101 performs various processes.

[0025] The first connection interface 104 is an interface through which the reading device 100 communicates with the driving device 200 .

[0026] The second connection interface 105 is an interface through which the reader 100 communicates with the terminal 400 .

[0027] The high frequency front end unit 106 outputs a high frequency signal to the antenna 300. The high frequency front end unit 106 also receives a high frequency signal from the antenna 300.

[0028] The digital amplitude modulation unit 107 adds information to be transmitted to the wireless tag 520 to a carrier wave to be transmitted to the wireless tag 520 .

[0029] The DA conversion unit converts the digital signal modulated by the digital amplitude modulation unit 107 into an analog signal. The DA conversion unit outputs the high-frequency signal to the antenna 300 via the high-frequency front-end unit .

[0030] The AD conversion unit 109 converts the high frequency signal input from the antenna 300 via the high frequency front end unit 106 into a digital signal.

[0031] The demodulation unit 110 extracts various information from the radio waves received from the wireless tag 520. For example, the demodulation unit 110 extracts a unique identification code stored in the wireless tag 520 from the digital signal converted by the AD conversion unit 109. Furthermore, when the radio waves of the wireless tag 520 are received by the antenna 300, the demodulation unit 110 outputs tag data of the wireless tag 520 in time series from the digital signal converted by the AD conversion unit 109 using known technology. The tag data is time series data based on the radio waves of the wireless tag 520 received by the antenna 300. The tag data includes phase data. The phase data is data indicating the phase of the radio waves from the wireless tag 520. The tag data includes radio wave reception strength (RSSI (received signal strength indicator)) data. The radio wave reception strength data is data indicating the reception strength of the radio waves from the wireless tag 520. The tag data may include both phase data and radio wave reception strength data.

[0032] The storage device 111 is a non-volatile memory that stores data, programs, etc. The storage device 111 is configured as, but not limited to, a hard disk drive (HDD) or a solid state drive (SSD). The storage device 111 stores programs that cause the processor 101 to execute various functions. The storage device 111 also stores data, etc., that the processor 101 uses when performing various processes.

[0033] The processor 101 executes the programs stored in the ROM 102 or the storage device 111 to perform the various functions of the reading device 100. The various functions of the reading device 100 include controlling the movement of the antenna 300 by the driving device 200, controlling communication via the antenna 300, determining the position of the wireless tag 520, reading information from the wireless tag 520, outputting information to the terminal 400, and the like.

[0034] (First embodiment) Next, a first embodiment of the radio tag communication device 10 will be described with reference to Fig. 3 and Fig. 4. Fig. 3 is a side view schematically showing an example of the configuration of the radio tag communication device 10 according to the first embodiment. Fig. 4 is a plan view schematically showing an example of the configuration of the radio tag communication device 10 according to the first embodiment.

[0035] The RFID tag communication device 10 according to the first embodiment has two antennas 310 and 320. The two antennas 310 and 320 are movably held by a driving device 200. The driving device 200 is installed below a table 540 on which an article 510 (e.g., a commodity) having an RFID tag 520 attached thereto is placed. That is, the two antennas 310 and 320 are movably arranged below the table 540.

[0036] 3 does not show the article 510, but shows only the wireless tag 520. In addition, in FIG. 4, the article 510 and the wireless tag 520 are not shown.

[0037] The table 540 is a plate-like member that is held horizontally. A placement range for the item 510, such as a commodity, is set on the table 540. The placement range is a range in which the item 510 is recommended to be placed. For example, the item 510 is placed in a basket 530 (e.g., a shopping basket), and the basket 530 is placed in the placement range on the table 540.

[0038] The radio tag communication device 10 reads information from the radio tag 520 attached to the article 510. The radio tag communication device 10 targets the radio tag 520 within the placement range to be read. However, the radio tag communication device 10 may also read information from a radio tag 520 that is not a target to be read and is located outside the placement range on the table 540. In particular, if a radio tag 520 that is not a target to be read is located near the placement range, there is a high possibility that the radio tag communication device 10 will erroneously read information from the radio tag 520 that is not a target to be read.

[0039] To avoid such erroneous reading, the radio tag communication device 10 determines whether the radio tag 520 is within the placement range, and only targets the radio tags 520 within the placement range for reading, reading information only from the radio tags 520 targeted for reading.

[0040] In one example, the position of the wireless tag 520 is determined based on the phase difference, which is the amount of change in phase, by measuring the phase of the wireless tag 520 while moving the antenna 300. In another example, the tag data of the wireless tag 520 is acquired at multiple positions while moving the antenna 300, and a trained model generated by machine learning using this data as input is used to determine the position of the wireless tag 520.

[0041] For this purpose, the driving device 200 moves the antennas 310 and 320. The driving device 200 has a stage 210 that holds the antennas 310 and 320, and a movement mechanism 220 that moves the stage 210.

[0042] The stage 210 holds the antennas 310 and 320 apart from each other with the radiation surfaces of the antennas 310 and 320 facing the table 540. For example, the stage 210 is a rectangular plate-shaped member.

[0043] The movement mechanism 220 is a rotation mechanism that rotates the stage 210 around a rotation center axis 226. The movement mechanism 220 includes a holder 221 and a motor 222.

[0044] The holder 221 holds the stage 210 horizontally. That is, the holder 221 holds the stage 210 parallel to the table 540. The holder 221 is fixed to the rotation shaft of the motor 222.

[0045] The motor 222 rotates the holder 221 around a rotation center axis 226. The rotation center axis 226 is perpendicular to the horizontal plane. That is, the rotation center axis 226 is parallel to the vertical axis. The rotation center axis 226 passes through the midpoint between the two antennas 310 and 320. That is, the rotation center axis 226 passes through the bisecting point of the line segment connecting the centers of the two antennas 310 and 320. In other words, the two antennas 310 and 320 are arranged point-symmetrically with respect to the rotation center axis 226 of the motor 222. That is, the two antennas 310 and 320 are arranged on the circumference of a circle 225 whose center is the rotation center axis 226 of the motor 222, at equal angles relative to the rotation center axis 226. That is, the two antennas 310 and 320 are arranged with an angular position offset of 180 degrees with respect to the rotation center axis 226.

[0046] The movement mechanism 220 rotates the stage 210 around the central rotation axis 226. As a result, the two antennas 310 and 320 move along the circumference of the same circle 225.

[0047] The driving device 200 operates as follows under the control of the reading device 100. In other words, the reading device 100 controls the driving device 200 so that the driving device 200 operates as follows.

[0048] The driving device 200 rotates the stage 210 by 180 degrees for each measurement. As a result, the antenna 310 moves along the circumference of the circle 225 to the position where the antenna 320 was located before the measurement. The antenna 320 moves along the circumference of the circle 225 to the position where the antenna 310 was located before the measurement. In other words, the driving device 200 moves the two antennas 310, 320 so that the two antennas 310, 320 share the entire trajectory that is traced by the two antennas 310, 320.

[0049] Therefore, the trajectory of one circumference of the circle 225 that the antennas 310, 320 need to trace in one measurement can be traced by moving the two antennas 310, 320 only halfway around the circle 225. That is, the RFID tag communication device 10 according to the first embodiment requires half the time for measurement compared to a RFID tag communication device that performs measurement using one antenna. As a result, the RFID tag communication device 10 according to the first embodiment can perform measurement in half the time required compared to a RFID tag communication device that performs measurement using one antenna. That is, according to this embodiment, a RFID tag communication device 10 that can read information from the RFID tag 520 in a short time is provided.

[0050] (First Modification) Next, a first modified example of the first embodiment of the radio tag communication device 10 will be described with reference to Fig. 5. Fig. 5 is a plan view schematically showing an example of the configuration of the radio tag communication device 10 according to the first modified example of the first embodiment. Fig. 5 is a view corresponding to Fig. 4. In Fig. 5, like Fig. 4, the article 510 and the radio tag 520 are not shown.

[0051] The RFID tag communication device 10 according to this modification has three antennas 310, 320, and 330. The three antennas 310, 320, and 330 are movably held by a driving device 200 installed under a table 540.

[0052] The driving device 200 has a stage 210 that holds the antennas 310 , 320 , and 330 , and a movement mechanism 220 that moves the stage 210 .

[0053] The stage 210 holds the antennas 310, 320, and 330 apart from one another with the radiation surfaces of the antennas 310, 320, and 330 facing the table 540. For example, the stage 210 is a circular plate-like member.

[0054] The moving mechanism 220 is a rotation mechanism that rotates the stage 210 around a central rotation axis 226. The configuration of the moving mechanism 220 is as described above.

[0055] The three antennas 310, 320, and 330 are arranged on the circumference of a circle 225 whose center is the central axis of rotation 226 of the motor 222, at equal angles relative to the central axis of rotation 226. In other words, the three antennas 310, 320, and 330 are arranged with their angular positions offset by 120 degrees relative to the central axis of rotation 226.

[0056] The movement mechanism 220 rotates the stage 210 around the central rotation axis 226. As a result, the three antennas 310, 320, and 330 move along the circumference of the same circle 225.

[0057] The driving device 200 operates as follows under the control of the reading device 100. In other words, the reading device 100 controls the driving device 200 so that the driving device 200 operates as follows.

[0058] The driving device 200 rotates the stage 210 by 120 degrees for each measurement. As a result, the antenna 310 moves along the circumference of the circle 225 to the position where the antenna 320 was located before the measurement. The antenna 320 moves along the circumference of the circle 225 to the position where the antenna 330 was located before the measurement. The antenna 330 moves along the circumference of the circle 225 to the position where the antenna 310 was located before the measurement. In other words, the driving device 200 moves the three antennas 310, 320, and 330 so that the three antennas 310, 320, and 330 share the entire trajectory described by the three antennas 310, 320, and 330.

[0059] Therefore, the trajectory of one circumference of the circle 225 that the antennas 310, 320, and 330 must trace in one measurement can be traced by moving the three antennas 310, 320, and 330 one-third of the circumference of the circle 225. That is, the RFID tag communication device 10 according to this modification requires one-third of the time for measurement compared to an RFID tag communication device that performs measurement using one antenna. As a result, the RFID tag communication device 10 according to this modification can perform measurement in one-third the time required compared to an RFID tag communication device that performs measurement using one antenna. In other words, this modification provides an RFID tag communication device 10 that can read information from the RFID tag 520 in a short time.

[0060] In this modification, the three antennas 310, 320, and 330 do not necessarily need to be arranged on the circumference of the circle 225 at equal angles relative to the rotational axis 226. The angle formed by two of the three antennas 310, 320, and 330 relative to the rotational axis 226 may be different from the angle formed by the other two.

[0061] For example, the three antennas 310, 320, and 330 may be arranged on the circumference of the circle 225 such that the antennas 310 and 320 form an angle of 90 degrees, the antennas 320 and 330 form an angle of 120 degrees, and the antennas 330 and 310 form an angle of 150 degrees with respect to the rotation central axis 226. In this case, the driving device 200 rotates the stage 210 by 150 degrees around the rotation central axis 226 so that the three antennas 310, 320, and 330 share the entire trajectory drawn by the three antennas 310, 320, and 330 in one measurement.

[0062] (Second Modification) Next, a second modified example of the first embodiment of the radio tag communication device 10 will be described with reference to Fig. 6. Fig. 6 is a plan view schematically showing an example of the configuration of the radio tag communication device 10 according to the second modified example of the first embodiment. Fig. 6 is a view corresponding to Fig. 4. In Fig. 6, as in Fig. 4, the article 510 and the radio tag 520 are not shown.

[0063] The RFID tag communication device 10 according to this modification has four antennas 310, 320, 330, and 340. The four antennas 310, 320, 330, and 340 are movably held by a driving device 200 installed under a table 540.

[0064] The driving device 200 has a stage 210 that holds the antennas 310 , 320 , 330 , and 340 , and a movement mechanism 220 that moves the stage 210 .

[0065] The stage 210 holds the antennas 310, 320, 330, and 340 with the radiation surfaces of the antennas 310, 320, 330, and 340 facing the table 540. For example, the stage 210 is a circular plate-shaped member.

[0066] The moving mechanism 220 is a rotation mechanism that rotates the stage 210 around a central rotation axis 226. The configuration of the moving mechanism 220 is as described above.

[0067] The four antennas 310, 320, 330, and 340 are arranged on the circumference of a circle 225 whose center is the central axis of rotation 226 of the motor 222, at equal angles relative to the central axis of rotation 226. In other words, the four antennas 310, 320, 330, and 340 are arranged with their angular positions shifted by 90 degrees relative to the central axis of rotation 226.

[0068] The movement mechanism 220 rotates the stage 210 around the central rotation axis 226. As a result, the four antennas 310, 320, 330, and 340 move along the circumference of the same circle 225.

[0069] The driving device 200 operates as follows under the control of the reading device 100. In other words, the reading device 100 controls the driving device 200 so that the driving device 200 operates as follows.

[0070] The driving device 200 rotates the stage 210 by 90 degrees for each measurement. As a result, the antenna 310 moves along the circumference of the circle 225 to the position where the antenna 320 was located before the measurement. The antenna 320 moves along the circumference of the circle 225 to the position where the antenna 330 was located before the measurement. The antenna 330 moves along the circumference of the circle 225 to the position where the antenna 340 was located before the measurement. The antenna 340 moves along the circumference of the circle 225 to the position where the antenna 310 was located before the measurement. In other words, the driving device 200 moves the four antennas 310, 320, 330, and 340 so that each of the four antennas 310, 320, 330, and 340 shares the entire trajectory described by the four antennas 310, 320, 330, and 340.

[0071] Therefore, the trajectory of one circumference of the circle 225 that the antennas 310, 320, 330, and 340 must trace in one measurement can be traced by moving the four antennas 310, 320, 330, and 340 a quarter of the circumference of the circle 225. That is, the RFID tag communication device 10 according to this modification requires only a quarter of the time for measurement compared to a RFID tag communication device that performs measurement using a single antenna. As a result, the RFID tag communication device 10 according to this modification can perform measurement in a quarter of the time required compared to a RFID tag communication device that performs measurement using a single antenna. In other words, this modification provides an RFID tag communication device 10 that can read information from the RFID tag 520 in a short time.

[0072] In this modification, the four antennas 310, 320, 330, and 340 do not necessarily have to be arranged on the circumference of the circle 225 at equal angles relative to the rotational axis 226. The angle formed by any two adjacent antennas of the four antennas 310, 320, 330, and 340 relative to the rotational axis 226 may be different from the angle formed by any other two adjacent antennas. This is the same as in the second modification, and a description thereof will be omitted.

[0073] (Second embodiment) Next, a second embodiment of the radio tag communication device 10 will be described with reference to Fig. 7. Fig. 7 is a side view schematically showing an example of the configuration of the radio tag communication device 10 according to the second embodiment. Fig. 7 is a view corresponding to Fig. 3. As in Fig. 3, the article 510 is not shown in Fig. 7. The following description will focus on the differences from the first embodiment.

[0074] The RFID tag communication device 10 according to the second embodiment has two antennas 350 and 360. The two antennas 350 and 360 are movably held by a driving device 200 installed under a table 540.

[0075] The driving device 200 has a stage 230 that holds the antennas 350 and 360 , and a movement mechanism 240 that moves the stage 230 .

[0076] The stage 230 holds the antennas 350, 360 with their radiation surfaces facing the table 540. For example, the stage 230 is a rectangular plate-shaped member. The stage 230 holds the antennas 350, 360 at a distance of L / 2 in the X-axis direction in FIG. 7 . Here, L / 2 is the center-to-center distance of the two antennas 350, 360, and is equal to the stroke of the movement mechanism 240, i.e., the movement width of the antennas 350, 360 by the movement mechanism 240.

[0077] The movement mechanism 240 is a linear movement mechanism that moves the stage 230 linearly. The movement mechanism 240 has a guide rail 241 and a motor 245. The guide rail 241 holds the stage 230 so that it can move linearly. The movement direction of the stage 230 coincides with the direction in which the antennas 350 and 360 are spaced apart, i.e., the X-axis direction. For example, the guide rail 241 has a ball screw 242 therein. The ball screw 242 has a rotatable screw shaft 243 and a nut 244 that can move along the screw shaft 243 as the screw shaft 243 rotates. The nut 244 holds the stage 230. The motor 245 rotates the screw shaft 243. The rotational motion of the screw shaft 243 is converted into linear motion of the nut 244.

[0078] Therefore, by rotating the motor 245, the stage 230 is moved linearly in the horizontal direction (X-axis direction). For example, by rotating the motor 245 forward, the stage 230 is moved linearly in the +X direction, and by rotating the motor 245 backward, the stage 230 is moved linearly in the -X direction. In other words, by switching the rotation direction of the shaft of the motor 245, the stage 230 is moved back and forth in the X-axis direction.

[0079] The driving device 200 operates as follows under the control of the reading device 100. In other words, the reading device 100 controls the driving device 200 so that the driving device 200 operates as follows.

[0080] The driving device 200 moves the stage 230 by a distance of L / 2 along the X axis for each measurement. In the example of Fig. 7, the driving device 200 moves the stage 230 by a distance of L / 2 in the +X direction. In addition, for the next measurement, the driving device 200 moves the stage 230 by a distance of L / 2 in the -X direction.

[0081] 7, the antenna 350 moves to the position where the antenna 360 was located before the measurement. In other words, the driving device 200 moves the two antennas 350, 360 so that the two antennas 350, 360 share the entire trajectory drawn by the two antennas 350, 360.

[0082] Therefore, the locus of distance L that the antennas 350, 360 need to trace in one measurement can be traced by moving the two antennas 350, 360 by a distance of L / 2. That is, the RFID tag communication device 10 according to the second embodiment requires half the time for measurement compared to a RFID tag communication device that performs measurement using one antenna. As a result, the RFID tag communication device 10 according to the second embodiment can perform measurement in half the time required compared to a RFID tag communication device that performs measurement using one antenna. That is, according to this embodiment, a RFID tag communication device 10 that can read information from the RFID tag 520 in a short time is provided.

[0083] In this embodiment, an example has been described in which the driving device 200 has two antennas 350 and 360, but the driving device 200 may have three or more antennas. In this case, the stroke can be shortened by the number of antennas, thereby shortening the time required for one measurement.

[0084] (Third embodiment) Next, a third embodiment of the radio tag communication device 10 will be described with reference to Fig. 8. Fig. 8 is a side view schematically showing an example of the configuration of the radio tag communication device 10 according to the third embodiment. Fig. 8 is a view corresponding to Fig. 7. As in Fig. 7, the article 510 is not shown in Fig. 8. The following description will focus on the differences from the second embodiment.

[0085] The RFID tag communication device 10 according to the third embodiment has two antennas 370 and 380. The two antennas 370 and 380 are movably held by a driving device 200 installed under a table 540.

[0086] The driving device 200 has a stage 250 that holds the antenna 370 , a movement mechanism 260 that moves the stage 250 , a stage 270 that holds the antenna 380 , and a movement mechanism 280 that moves the stage 270 .

[0087] Stage 250 holds antenna 370 with the radiation surface of antenna 370 facing table 540. Stage 270 holds antenna 380 with the radiation surface of antenna 380 facing table 540. For example, stages 250 and 270 are rectangular plate-shaped members.

[0088] The movement mechanisms 260 and 280 are linear movement mechanisms that respectively linearly move the stages 250 and 270. The configuration of the movement mechanisms 260 and 280 is similar to that of the movement mechanism 240 in the second embodiment.

[0089] That is, the movement mechanism 260 has a guide rail 261 and a motor 265. The guide rail 261 holds the stage 250 so that it can move linearly. The guide rail 261 has a ball screw 262 therein. The ball screw 262 has a screw shaft 263 and a nut 264. The nut 264 holds the stage 250. The motor 265 rotates the screw shaft 263. The rotational motion of the screw shaft 263 is converted into linear motion of the nut 264.

[0090] Similarly, the movement mechanism 280 has a guide rail 281 and a motor 285. The guide rail 281 holds the stage 270 so that it can move linearly. The guide rail 281 has a ball screw 282 therein. The ball screw 282 has a screw shaft 283 and a nut 284. The nut 284 holds the stage 270. The motor 285 rotates the screw shaft 283. The rotational motion of the screw shaft 283 is converted into linear motion of the nut 284.

[0091] The movement mechanisms 260, 280 are installed so that their movement directions are aligned with each other, for example, so that the central rotation axes of the screw shafts 263, 283 are aligned with each other. Furthermore, the movement mechanisms 260, 280 are both installed so that the motors 265, 285 are positioned outside the table 540. Furthermore, the movement mechanisms 260, 280 are installed so that the tips of the guide rails 261, 281 are as close as possible to each other.

[0092] The stroke of the movement mechanism 260, i.e., the movement width of the antenna 370 by the movement mechanism 260, is La. Furthermore, the stroke of the movement mechanism 280, i.e., the movement width of the antenna 380 by the movement mechanism 280, is Lb. For example, La and Lb are equal to each other. La and Lb may also be different from each other.

[0093] The moving mechanisms 260, 280 move the antennas 370, 380 in synchronization with each other. For example, the moving mechanisms 260, 280 move the antennas 370, 380 from outside to inside and from inside to outside. The moving mechanisms 260, 280 may also move the antennas 370, 380 from right to left and from left to right.

[0094] The driving device 200 operates as follows under the control of the reading device 100. In other words, the reading device 100 controls the driving device 200 so that the driving device 200 operates as follows.

[0095] For each measurement, the driving device 200 causes the movement mechanisms 260 and 280 to move the stages 250 and 270 along the X axis in synchronization with each other. As a result, the antennas 370 and 380 move in synchronization with each other. In the example of Fig. 8, the driving device 200 moves the antennas 370 and 380 from the outside to the inside. Furthermore, in the next measurement, the driving device 200 moves the antennas 370 and 380 from the inside to the outside.

[0096] In other words, the driving device 200 moves the two antennas 370, 380 so that the two antennas 370, 380 share the entire trajectory drawn by the two antennas 370, 380.

[0097] Therefore, the locus of distance La+Lb drawn by the antennas 370, 380 in one measurement can be drawn by moving the two antennas 370, 380 by the distances La and Lb. That is, the RFID tag communication device 10 according to the third embodiment requires approximately half the time for measurement compared to an RFID tag communication device that performs measurement using one antenna. As a result, the RFID tag communication device 10 according to the third embodiment can perform measurement in approximately half the time required compared to an RFID tag communication device that performs measurement using one antenna. That is, according to this embodiment, a RFID tag communication device 10 that can read information from a RFID tag 520 in a short time is provided.

[0098] In this embodiment, an example has been described in which the driving device 200 moves the antennas 370, 380 closer to or farther away from each other. However, the driving device 200 may also move the antennas 370, 380 from right to left or from left to right while maintaining a constant distance therebetween.

[0099] Although several 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 embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the scope of the invention and its equivalents as defined in the claims. [Explanation of symbols]

[0100] 10...wireless tag communication device, 100...reader, 101...processor, 102...ROM, 103...RAM, 104...connection interface, 105...connection interface, 106...high frequency front end section, 107...digital amplitude modulation section, 108...DA conversion section, 109...AD conversion section, 110...demodulation section, 111...storage device, 112...bus, 200...drive device, 210...stage, 220...movement mechanism, 221...holding section, 222...motor, 225...circle, 226...rotation center axis, 230...stage, 240...movement mechanism, 241...guide rail, 242...ball screw, 243...screw shaft, 2 44...nut, 245...motor, 250...stage, 260...moving mechanism, 261...guide rail, 262...ball screw, 263...screw shaft, 264...nut, 265...motor, 270...stage, 280...moving mechanism, 281...guide rail, 282...ball screw, 283...screw shaft, 284...nut, 285...motor, 300...antenna, 310...antenna, 320...antenna, 330...antenna, 340...antenna, 350...antenna, 360...antenna, 370...antenna, 380...antenna, 400...terminal, 510...item, 520...wireless tag, 530...basket, 540...table.

Claims

1. a plurality of antennas disposed under a table on which an article having a wireless tag attached thereto is placed; a reader that communicates with the wireless tag via the antenna and reads information from the wireless tag located within a placement range on the table on which the article is placed; a driving device that moves the plurality of antennas so that the plurality of antennas share the entire trajectory of the plurality of antennas; A wireless tag communication device having the above.

2. the driving device moves the antennas so that the antennas move along the circumference of the same circle. The radio tag communication device according to claim 1 .

3. the plurality of antennas are N antennas (N is an integer of 2 or more) arranged at equal angles with respect to the center of the circle, the driving device moves the N antennas such that each of the N antennas moves by (360 / N) degrees around the center of the circle; The radio tag communication device according to claim 2 .

4. The plurality of antennas are arranged along a straight line, the driving device moves the plurality of antennas along the straight line so that one of the plurality of antennas is positioned at the position of another of the plurality of antennas; The radio tag communication device according to claim 1 .

5. The plurality of antennas are arranged along a straight line, the driving device moves the plurality of antennas along the straight line in synchronization with one another; The radio tag communication device according to claim 1 .

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