Wireless tag communication device

Abstract

To provide a wireless tag communication device capable of highly accurately detecting a target wireless tag and reading information therefrom.SOLUTION: A wireless tag communication device according to an embodiment comprises at least one antenna, a reading device, and a driving device. The antenna is provided on a lower side of a table for placing thereon an article with a wireless tag attached thereto. The reading device communicates with wireless tags via the antenna to detect a wireless tag in a placement area on the table for placing articles and read information from the wireless tag in the placement area. The driving device moves the antenna inside the placement area.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 emitting electromagnetic waves from an antenna and receiving electromagnetic waves transmitted from the wireless tag in response to the electromagnetic waves. [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] Since a radio-frequency tag communication device may detect non-target radio-frequency tags that are present around a target radio-frequency tag, it is desirable for the radio-frequency tag communication device to be able to detect the target radio-frequency tag with high accuracy and selectively read the information of the target radio-frequency tag.

[0006] The problem to be solved by the present invention is to provide a radio frequency tag communication device that detects a target radio frequency tag with high accuracy and reads information from the target radio frequency tag. [Means for solving the problem]

[0007] The RFID tag communication device according to the embodiment includes at least one antenna, a reader, and a drive unit. The antenna is disposed below a table on which an item with a RFID tag is placed. The reader communicates with the RFID tag via the antenna, detects the RFID tag within a placement range on the table on which the item is placed, and reads information from the RFID tag within the placement range. The drive unit moves the antenna within the placement range. [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 showing an example of the configuration of the radio tag communication device according to the first embodiment. [Figure 5] FIG. 5 is a flowchart showing an example of the flow of the operation of the radio tag communication device according to the first embodiment. [Figure 6] FIG. 6 is a side view schematically showing an example of the configuration of a radio tag communication device according to the second embodiment. [Figure 7] FIG. 7 is a plan view schematically showing an example of the configuration of the 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. [Figure 9] FIG. 9 is a plan 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 720 attached to an item 710 such as a commodity is within a predetermined range, reads information from the wireless tag 720 for the wireless tag 720 within the predetermined range, and processes the read information.

[0012] 1 shows one item 710 and one wireless tag 720 for convenience, but this does not mean that there are any particular number of items 710 and wireless tags 720. The number of items 710 and wireless tags 720 may be one or more, and generally there are more than one. One wireless tag 720 is attached to one item 710.

[0013] The RFID tag communication device 10 includes a reader 100, a driving device 200, an antenna 300, a terminal 400, a sensor 500, and a notification device 600.

[0014] The reader 100 controls the driving device 200 and the antenna 300 to read information from the wireless tag 720. 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 720. The antenna 300 emits electromagnetic waves. The antenna 300 also receives electromagnetic waves transmitted from the wireless tag 720 in response to the electromagnetic wave emission. The antenna 300 converts the radio waves received from the wireless tag 720 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 720 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 sensor 500 is a device for acquiring location information of the wireless tag 720. For example, the sensor 500 may be a camera. For example, the reading device 100 may be configured to analyze an image captured by the camera to acquire location information of the wireless tag 720. Alternatively, the camera itself may be capable of acquiring location information of the wireless tag 720. Furthermore, the sensor 500 may be any device other than a camera as long as it can acquire location information of the wireless tag 720.

[0019] Notification device 600 is a device that notifies information. Notification device 600 may include a speaker and notify information by audio output. Notification device 600 may also include a display and notify information by image display. Of course, notification device 600 may also be a device that notifies information by audio output and image display.

[0020] The wireless tag 720 is typically an RFID (radio frequency identification) tag. The wireless tag 720 may be another type of wireless tag. The wireless tag 720 is a passive wireless tag that operates using a predetermined radio wave emitted from the antenna 300 as its energy source. The wireless tag 720 emits a signal including information stored in the wireless tag 720 by performing backscatter modulation on an unmodulated signal. For example, the information stored in the wireless tag 720 includes uniquely identifiable identification information. For example, the information stored in the wireless tag 720 includes information about the item 710 to which the wireless tag 720 is attached.

[0021] (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.

[0022] 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 108, a digital amplitude modulation unit 109, a DA (digital to analog) conversion unit 120, an AD (analog to digital) conversion unit 111, a demodulation unit 112, and a storage device 113. The units included in the reading device 100 can communicate with each other via a bus 114.

[0023] 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 113 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.

[0024] 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.

[0025] 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.

[0026] 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.

[0027] The first connection interface 104 is an interface through which the reading device 100 communicates with the driving device 200 .

[0028] The second connection interface 105 is an interface through which the reader 100 communicates with the terminal 400 .

[0029] The third connection interface is an interface through which the reader 100 communicates with the sensor 500 .

[0030] The fourth connection interface is an interface through which the reading device 100 communicates with the notification device 600 .

[0031] The high frequency front end unit 108 outputs a high frequency signal to the antenna 300. The high frequency front end unit 108 also receives a high frequency signal from the antenna 300.

[0032] The digital amplitude modulation unit 109 adds information to be transmitted to the wireless tag 720 to a carrier wave to be transmitted to the wireless tag 720 .

[0033] The DA conversion unit 120 converts the digital signal modulated by the digital amplitude modulation unit 109 into an analog signal. The DA conversion unit 120 outputs the high-frequency signal to the antenna 300 via the high-frequency front-end unit .

[0034] The AD conversion unit 111 converts the high frequency signal input from the antenna 300 via the high frequency front end unit 108 into a digital signal.

[0035] The demodulation unit 112 extracts various information from the radio waves received from the wireless tag 720. For example, the demodulation unit 112 extracts a unique identification code stored in the wireless tag 720 from the digital signal converted by the AD conversion unit 111. Furthermore, when the radio waves of the wireless tag 720 are received by the antenna 300, the demodulation unit 112 outputs tag data of the wireless tag 720 in time series from the digital signal converted by the AD conversion unit 111 using known technology. The tag data is time series data based on the radio waves of the wireless tag 720 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 720. 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 720. The tag data may include both phase data and radio wave reception strength data.

[0036] The storage device 113 is a non-volatile memory that stores data, programs, etc. The storage device 113 is configured as, but is not limited to, an HDD (Hard Disk Drive) or an SSD (Solid State Drive). The storage device 113 stores programs that cause the processor 101 to execute various functions. The storage device 113 also stores data, etc. that the processor 101 uses when performing various processes.

[0037] The processor 101 executes the programs stored in the ROM 102 or the storage device 113 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 720, reading information from the wireless tag 720, outputting information to the terminal 400, and the like.

[0038] (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. Figs. 3 and 4 omit the illustration of the article 710 and only show the radio tag 720.

[0039] The RFID tag communication device 10 according to the first embodiment has an antenna 310. The antenna 310 is movably held by a driving device 200. The driving device 200 is installed below a table 740 on which an article 710 (e.g., a commodity) having a RFID tag 720 attached thereto is placed. That is, the antenna 310 is movably disposed below the table 740.

[0040] The table 740 is a plate-like member that is held horizontally. A placement range Ra is set on the upper surface of the table 740. The placement range Ra is an area that is assumed in advance to be where the wireless tag 720 will be placed. For example, the placement range Ra is an area where an item 710 with a wireless tag 720 attached or a basket 730 (e.g., a shopping basket) containing the item 710 will be placed. For example, the outline of the placement range Ra is circular. However, the outline of the placement range Ra is not limited to this and may be, for example, rectangular or elliptical.

[0041] The driving device 200 moves the antenna 310. The driving device 200 has a stage 210 that holds the antenna 310 and a movement mechanism 220 that moves the stage 210.

[0042] The stage 210 holds the antenna 310 with the radiation surface of the antenna 310 facing the table 740. The stage 210 has a base plate 231 and an inclined holder 232.

[0043] The base plate 231 is held horizontally by the movement mechanism 220. For example, the base plate 231 is a rectangular plate-shaped member.

[0044] The tilted holding portion 232 is provided upright on the base plate 231. The tilted holding portion 232 holds the antenna 310 at an angle so that the radiation surface of the antenna 310 faces upward in the placement range Ra.

[0045] 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.

[0046] The holder 221 holds the stage 210 horizontally. That is, the holder 221 holds the stage 210 parallel to the table 740. The holder 221 is fixed to the rotation shaft of the motor 222.

[0047] The motor 222 rotates the holder 221 around a rotation center axis 226. The rotation center axis 226 is perpendicular to the horizontal plane. In other words, the rotation center axis 226 is parallel to the vertical axis.

[0048] The movement mechanism 220 rotates the stage 210 around the central rotation axis 226. As a result, the antenna 310 moves along the circumference of the circle 225.

[0049] The radio tag communication device 10 reads information from a radio tag 720 attached to an article 710. The radio tag communication device 10 targets the radio tags 720 within the placement range Ra to be read. However, the radio tag communication device 10 may also read information from a radio tag 720 that is not a target to be read and is located outside the placement range Ra on the table 740. In particular, if a radio tag 720 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 720 that is not a target to be read.

[0050] To avoid such erroneous reading, the radio tag communication device 10 detects the radio tag 720, determines whether the detected radio tag 720 is within the placement range Ra, and reads only the radio tags 720 within the placement range Ra, reading information only from the radio tags 720 that are the target of reading.

[0051] In one example, the position of the wireless tag 720 is determined based on a phase difference, which is the amount of change in phase, by measuring the phase of the wireless tag 720 while moving the antenna 300. In another example, the tag data of the wireless tag 720 is acquired at multiple positions by moving the antenna 300, and the position determination as to whether the wireless tag 720 is within the placement range Ra is performed using a trained model generated by machine learning using this as input.

[0052] Furthermore, when performing measurement, the radio tag communication device 10 requests the user of the radio tag communication device 10 to place the radio tag 720 within the placement range Ra. Here, measurement includes detecting the radio tag 720, determining the position of the radio tag 720, and reading information from the radio tag 720.

[0053] Therefore, the wireless tag communication device 10 determines whether the wireless tag 720 is within the placement range Ra based on information from the sensor 500, and if the wireless tag 720 is at least partially outside the placement range Ra, it notifies the user through the notification device 600 to prompt them to correct the position of the wireless tag 720.

[0054] For example, when an article 710 with an attached wireless tag 720 or a basket 730 containing the article 710 goes outside the placement range Ra, the wireless tag communication device 10 notifies the user to urge them to correct the position of the article 710 or the basket 730. If the article 710 or the basket 730 is within the placement range Ra, it is guaranteed that the wireless tag 720 is within the placement range Ra.

[0055] Driving device 200 moves antenna 310 two-dimensionally within placement range Ra. Here, moving antenna 310 two-dimensionally means that when two mutually independent axes, for example, an X axis and a Y axis that are orthogonal to each other, are set within a plane parallel to the upper surface of table 740, the coordinates along the two axes of antenna 310, for example, the X coordinate and the Y coordinate, both change regardless of how the axes are set.

[0056] In this embodiment, the driving device 200 moves the antenna 310 inside the mounting range Ra along the circumference of a circle 256. For example, the outline of the mounting range Ra is a circle that matches the trajectory described by the outermost point 311 of the antenna 310 when the stage 210 is rotated around the rotation center axis 226.

[0057] In other words, in order to preferentially detect the wireless tags 720 within the placing range Ra with high accuracy, the placing range Ra is set to a circular shape in accordance with the trajectory of the antenna 310. This is based on the idea that the wireless tags 720 within the placing range Ra are more likely to be detected by the wireless tag communication device 10 than the wireless tags 720 outside the placing range Ra.

[0058] The placement range Ra is not necessarily limited to a range that coincides with the above circle. The placement range Ra may be set to a range wider or narrower than the above circle. The shape of the placement range Ra is also not limited to a circle and may be another shape. However, the wider the placement range Ra is than the above circle, the higher the frequency of detecting non-target wireless tags 720, and conversely, the narrower the placement range Ra is than the above circle, the higher the frequency of missing the target wireless tags 720. Therefore, it is preferable to set the placement range Ra to a range close to the above circle.

[0059] An example of the operation of the device 10 for communicating with a radio tag according to this embodiment will be described below with reference to Fig. 5. Fig. 5 is a flowchart showing the flow of an example of the operation of the device 10 for communicating with a radio tag according to this embodiment.

[0060] First, in ACT11, the reading device 100 acquires information including the location information of the wireless tag 720 from the sensor 500. For example, the sensor 500 is a camera, and the reading device 100 acquires an image captured by the camera.

[0061] Next, in ACT12, the reading device 100 calculates the relative position between the wireless tag 720 and the placement range Ra from the acquired captured image using image processing technology. For example, when the article 710 with the wireless tag 720 attached is placed alone on the table 740, the reading device 100 calculates the relative position between the article 710 and the placement range Ra. When the article 710 with the wireless tag 720 attached is placed in a basket 730 and placed on the table 740, the reading device 100 calculates the relative position between the basket 730 and the placement range Ra.

[0062] The position information of the placement range Ra required at this time may be obtained by, for example, marking a circle or other mark indicating the placement range Ra on the table 740 in advance and using image processing technology, or the information on the placement range Ra may be stored in advance.

[0063] Next, in ACT13, the reading device 100 determines whether the wireless tag 720 is within the placement range Ra. Therefore, the reading device 100 determines whether the article 710 or the basket 730 is within the placement range Ra. If the article 710 or the basket 730 is within the placement range Ra, it is guaranteed that the wireless tag 720 is within the placement range Ra.

[0064] For example, whether the item 710 or the basket 730 is within the placement range Ra can be determined by whether the outline of the item 710 or the basket 730 is located inside the placement range Ra without overlapping with the outline of the placement range Ra.

[0065] If the article 710 or the basket 730 is not within the placement range Ra (NO in ACT13), in ACT14 the reading device 100 issues a notification via the notification device 600 to prompt the user to correct the position of the article 710 or the basket 730. Thereafter, the reading device 100 returns to the processing of ACT11 and performs the processing of ACT11 to ACT13 again.

[0066] If the item 710 or basket 730 is within the placement range Ra (YES in ACT13), in ACT15, the reading device 100 detects the wireless tags 720 and determines, for each of the detected wireless tags 720, whether the wireless tag 720 is within the placement range Ra.

[0067] Next, in ACT16, the reader 100 reads information from the wireless tag 720 within the placement range Ra.

[0068] In the RFID tag communication device 10 according to this embodiment, the driving device 200 moves the antenna 310 two-dimensionally inside the placement range Ra. For example, inside the placement range Ra, the driving device 200 moves the antenna 310 along the circumference of a circle 225. Therefore, the electromagnetic waves radiated from the antenna 310 are radiated more inside the placement range Ra and less outside the placement range Ra. Therefore, the RFID tag communication device 10 can detect the target RFID tag 720 within the placement range Ra with high accuracy and selectively read information from the target RFID tag 720.

[0069] Furthermore, the stage 210 holds the antenna 310 with the radiation surface of the antenna 310 facing the table 740. This also contributes to improving the detection accuracy of the target wireless tag 720.

[0070] (Second embodiment) Next, a second embodiment of the radio tag communication device 10 will be described with reference to Fig. 6 and Fig. 7. Fig. 6 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 plan view schematically showing an example of the configuration of the radio tag communication device 10 according to the second embodiment. Figs. 6 and 7 correspond to Figs. 3 and 4, respectively. As with Figs. 3 and 4, Figs. 6 and 7 omit illustration of an article 710. The following description will focus on differences from the first embodiment.

[0071] The RFID tag communication device 10 according to the second embodiment has an antenna 320. The antenna 320 is movably held by a driving device 200 installed under a table 740. A placement range Rb is set on the upper surface of the table 740.

[0072] The driving device 200 moves the antenna 320 along two axes, the X-axis and the Y-axis, which are parallel to the horizontal plane and perpendicular to each other. To this end, the driving device 200 has a stage 230 that holds the antenna 320, a movement mechanism 240 that moves the stage 230, a stage 250 that holds the movement mechanism 240, and a movement mechanism 240 that moves the stage 250.

[0073] The stage 230 holds the antenna 320 with the radiation surface of the antenna 320 facing the table 740. For example, the stage 230 is a rectangular plate-shaped member.

[0074] The movement mechanism 240 is a linear movement mechanism that moves the stage 230 linearly in the X-axis direction. 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 in 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 movement of the screw shaft 243 is converted into linear movement of the nut 244.

[0075] 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 reversely, 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. As a result, the antenna 320 held by the stage 230 is moved back and forth in the X-axis direction.

[0076] The stage 250 horizontally holds the moving mechanism 240. Specifically, the stage 250 holds the moving mechanism 240 so that the moving direction of the moving mechanism 240 is horizontal. For example, the stage 250 is a rectangular plate-like member.

[0077] The movement mechanism 260 is a linear movement mechanism that moves the stage 250 linearly in the Y-axis direction. The movement mechanism 260 has a configuration similar to that of the movement mechanism 240. 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 in the Y-axis direction. For example, the guide rail 261 has a ball screw 262 therein. The ball screw 262 has a rotatable screw shaft 263 and a nut 264 that can move along the screw shaft 263 as the screw shaft 263 rotates. 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.

[0078] Therefore, by rotating the motor 265, the stage 250 is moved linearly in the horizontal direction (Y-axis direction). For example, by rotating the motor 265 forward, the stage 250 is moved linearly in the +Y direction, and by rotating the motor 265 backward, the stage 250 is moved linearly in the -Y direction. In other words, by switching the rotation direction of the shaft of the motor 265, the stage 250 is moved back and forth in the Y-axis direction. As a result, the movement mechanism 240 held by the stage 250 is moved back and forth in the Y-axis direction, and the antenna 320 held by the movement mechanism 240 is moved back and forth in the Y-axis direction.

[0079] The driving device 200 moves the antenna 310 two-dimensionally inside the placement range Rb. In this embodiment, the driving device 200 moves the antenna 310 along two axes inside the placement range Rb.

[0080] For example, as shown in Fig. 7, the mounting range Rb is set to a rectangle. Within the mounting range Rb, the driving device 200 moves the antenna 310 along two axes, the X-axis and the Y-axis, so that the antenna 310 moves along a path including a plurality of straight lines La, Lb, and Lc. The driving device 200 moves the antenna 310 in a so-called zigzag pattern.

[0081] Specifically, the driving device 200 moves the antenna 310 in this order from position Pa to position Pb, from position Pb to position Pc, and from position Pc to position Pd. Positions Pa, Pb, Pc, and Pd are positions where the top, bottom, left, and right sides of the antenna 310 overlap with the top, bottom, left, and right sides of the placement range Rb, respectively. The top, bottom, left, and right directions follow the orientations in FIG. 7.

[0082] In other words, based on the same concept as in the first embodiment, the placing range Rb is set to a rectangle in accordance with the trajectory of the antenna 310 so that the wireless tags 720 within the placing range Rb are preferentially detected with high accuracy. That is, the placing range Rb is set to a rectangle in accordance with the movable range of the antenna 310 by the driving device 200.

[0083] Furthermore, the placement range Rb does not need to coincide with the movable range of the antenna 310 by the drive device 200, but based on the same concept as in the first embodiment, it is preferable to set it to a range that is close to the rectangular range of the movable range of the antenna 310 by the drive device 200.

[0084] Furthermore, the trajectory between two positions Pa, Pb, Pc, and Pd does not need to be limited to a straight line, but may be a curved line.

[0085] In the RFID tag communication device 10 according to this embodiment, the driving device 200 moves the antenna 310 two-dimensionally within the placement range Rb. For example, the driving device 200 moves the antenna 310 in a zigzag pattern within the placement range Rb. As a result, the electromagnetic waves emitted from the antenna 310 are radiated more toward the inside of the placement range Rb and less toward the outside of the placement range Rb. As a result, the RFID tag communication device 10 can detect the target RFID tag 720 within the placement range Rb with high accuracy and selectively read information from the target RFID tag 720.

[0086] (Third embodiment) Next, a third embodiment of the radio tag communication device 10 will be described with reference to Figs. 8 and 9. 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. 9 is a plan view schematically showing an example of the configuration of the radio tag communication device 10 according to the third embodiment. Figs. 8 and 9 correspond to Figs. 3 and 4, respectively. However, unlike Fig. 3, the orientation of the paper surface of Fig. 8 is perpendicular to the X-axis. As with Figs. 3 and 4, Figs. 8 and 9 omit illustration of an article 710. The following description will focus on differences from the first embodiment.

[0087] The RFID tag communication device 10 according to the third embodiment has 22 antennas 330, 340. The two antennas 330, 340 are movably held by a driving device 200 installed below a table 740. A placement range Rc is set on the upper surface of the table 740.

[0088] The driving device 200 moves the two antennas 330, 340 along the X axis parallel to the horizontal plane. To this end, the driving device 200 has a stage 270 that holds the two antennas 330, 340, and a movement mechanism 280 that moves the stage 270.

[0089] The stage 270 holds the two antennas 330 and 340 with their radiation surfaces facing the table 740 .

[0090] The stage 270 holds the antennas 330, 340 at a predetermined distance with the radiation surfaces of the antennas 330, 340 facing the table 740. The stage 270 has a base plate 271 and two inclined holders 272, 273.

[0091] The base plate 271 is held horizontally by the movement mechanism 280. For example, the base plate 271 is a rectangular plate-shaped member.

[0092] The two inclined holders 272, 273 are erected on the base plate 271. The inclined holder 272 holds the antenna 330 at an angle so that the radiation surface of the antenna 330 faces upward in the mounting range Rc. The inclined holder 273 holds the antenna 340 at an angle so that the radiation surface of the antenna 340 faces upward in the mounting range Rc. The inclined holders 272, 273 hold the antennas 330, 340 at an angle so that the radiation surfaces of the antennas 330, 340 face each other.

[0093] The movement mechanism 280 is a linear movement mechanism that moves the stage 270 linearly in the X-axis direction. 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 in the X-axis direction. For example, the guide rail 281 holds the stage 270 in the middle of the two antennas 330 and 340. For example, the guide rail 281 has a ball screw 282 therein. The ball screw 282 has a rotatable screw shaft 283 and a nut 284 that can move along the screw shaft 283 as the screw shaft 283 rotates. 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.

[0094] Therefore, by rotating motor 285, stage 270 is moved linearly in the horizontal direction (X-axis direction). For example, by rotating motor 285 forward, stage 270 is moved linearly in the +X direction, and by rotating motor 285 reversely, stage 270 is moved linearly in the -X direction. In other words, by switching the rotation direction of the shaft of motor 285, stage 270 is moved back and forth in the X-axis direction. As a result, two antennas 330, 340 held by stage 270 are moved back and forth in the X-axis direction.

[0095] The driving device 200 moves the two antennas 330, 340 inside the placement range Rc. In this embodiment, the driving device 200 moves the two antennas 330, 340 along the X axis inside the placement range Rc.

[0096] For example, the placement range Rc is set to a rectangular shape as shown in Fig. 9. The driving device 200 moves the two antennas 330 and 340 together along the X axis within the placement range Rc.

[0097] Specifically, the driving device 200 moves the antenna 330 from position Pe to position Pf, and moves the antenna 340 from position Pg to position Ph. Positions Pe and Pf are positions where the top sides of the antenna 330 both overlap the top side of the placement area Rc, and the left and right sides of the antenna 330 overlap the left and right sides of the placement area Rc, respectively. Positions Pg and Ph are positions where the bottom sides of the antenna 340 both overlap the bottom side of the placement area Rc, and the left and right sides of the antenna 340 overlap the left and right sides of the placement area Rc, respectively. Up, down, left, and right are indicated according to the orientations in FIG. 9.

[0098] In other words, based on the same concept as in the first embodiment, the placing range Rc is set to a rectangle in accordance with the trajectories of the antennas 330 and 340 so that the wireless tags 720 within the placing range Rc are preferentially detected with high accuracy. That is, the placing range Rc is set to a rectangle that surrounds the range in which the antennas 330 and 340 can be moved by the driving device 200.

[0099] Furthermore, the mounting range Rc does not need to coincide with the rectangle surrounding the movable range of the antennas 330, 340 by the drive unit 200, but based on the same concept as in the first embodiment, it is preferable to set it to a range close to the rectangle surrounding the movable range of the antennas 330, 340 by the drive unit 200.

[0100] The RFID tag communication device 10 according to this embodiment has two antennas 330, 340, and the driving device 200 moves the two antennas 330, 340 together within the placement range Rc. This produces the same effect as moving one antenna two-dimensionally within the placement range Rc. That is, the electromagnetic waves emitted from the two antennas 330, 340 are radiated more toward the inside of the placement range Rc and less toward the outside of the placement range Rc. Therefore, the RFID tag communication device 10 can detect the target RFID tag 720 within the placement range Rc with high accuracy and selectively read information from the target RFID tag 720.

[0101] 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]

[0102] 10...wireless tag communication device, 100...reader, 101...processor, 102...ROM, 103...RAM, 104...connection interface, 105...connection interface, 108...high frequency front end unit, 109...digital amplitude modulation unit, 111...AD conversion unit, 112...demodulation unit, 113...storage device, 114...bus, 120...DA conversion unit, 200...drive unit, 210...stage, 220...movement mechanism, 221...holding unit, 222...motor, 225...circle, 226...rotation center axis, 230...stage, 231...base plate, 232...tilt holding unit, 240...movement mechanism, 241...guide rail, 242...ball screw, 243...screw shaft, 244 ...nut, 245...motor, 250...stage, 256...circle, 260...moving mechanism, 261...guide rail, 262...ball screw, 263...screw shaft, 264...nut, 265...motor, 270...stage, 271...base plate, 272...tilt holder, 273...tilt holder, 280...moving mechanism, 281...guide rail, 282...ball screw, 283...screw shaft, 284...nut, 285...motor, 300...antenna, 310...antenna, 311...outermost point, 320...antenna, 330...antenna, 340...antenna, 400...terminal, 500...sensor, 600...notification device, 710...item, 720...wireless tag, 730...basket, 740...table.

Claims

1. At least one antenna disposed under a table on which an item having a wireless tag attached thereto is placed; a reader that communicates with the wireless tag via the antenna, detects the wireless tag within a placement range on the table on which the article is placed, and reads information from the wireless tag within the placement range; a driving device that moves the antenna within the placement range; A wireless tag communication device having the above.

2. a sensor for acquiring location information of the wireless tag; a notification device for notifying information; and the reading device determines the relative position of the wireless tag with respect to the placement range, and when the wireless tag is at least partially out of the placement range, causes the notification device to notify information prompting correction of the position of the article; The radio tag communication device according to claim 1 .

3. The driving device moves the antenna so that the antenna moves along the circumference of a circle. The radio tag communication device according to claim 1 .

4. the drive unit moves the antenna along two axes so that the antenna moves along a trajectory including a plurality of straight lines; The radio tag communication device according to claim 1 .

5. The drive device is a stage that tilts and holds the antenna so that the radiation surface of the antenna faces upward in the placement range; a movement mechanism that moves the stage; having The radio tag communication device according to claim 1 .

Images