Information reading device

Abstract

The purpose of the present invention is to provide an information reading device with which reading accuracy is increased by avoiding unintended reading of an RFID tag. The information reading device includes an RFID reader body and an RFID antenna connected to the RFID reader body, and sets the value of an RSSI filter for each RFID tag on the basis of the tag data recorded in the RFID tag read by the RFID reader body.

Description

Information reading device

[0001] The present invention relates to an information reading device that reads information from multiple types of RFID (Radio Frequency Identification) tags.

[0002] For example, in an RFID system that uses the UHF band, there may be more than one type of RFID tag. The following are typical cases where two or more types of RFID tags are mixed: (1) when the IC of an RFID tag that was initially introduced is discontinued (production, sales, etc. are stopped), and a successor RFID tag is introduced, and (2) when there are a variety of objects to be managed, and some RFID tags are special tags such as metal-compatible tags.

[0003] When two or more types of RFID tags are used together, it is fine as long as the sensitivities of the RFID tags are the same, but if the sensitivities of the RFID tags are different, various operational problems will occur. For example, gate products usually incorporate an RSSI filter function to prevent false alarms from RFID tags that are far away, but when RFID tags with different sensitivities are used simultaneously, a single RSSI filter will have a large difference in detection distance. As a result, unintended RFID tag reading will occur, leading to gate malfunction.

[0004] Furthermore, shelf antenna products installed in libraries and other places require the use of an RSSI filter function to adjust sensitivity so that only the RFID tag placed on that shelf is read. However, when RFID tags with different sensitivities are used simultaneously, adjusting the sensitivity to match a low-sensitivity RFID tag will result in misreading of high-sensitivity RFID tags on other shelves, and adjusting the sensitivity to match a high-sensitivity RFID tag will result in the low-sensitivity RFID tag placed on that shelf not being read.

[0005] In response to the radio waves transmitted from the RFID reader / writer, a response signal transmitted from the RFID tag is received, and there is a technology that estimates the distance from the RFID reader / writer to the RFID tag based on the RSSI value and transmission parameters of this response signal (Patent Document 1).

[0006] Also, a reading system is known that includes a gate-type reader that is installed on the transport path and reads item identification information from an RF tag, and an IC information reader that is installed upstream of the gate-type reader and reads IC information from the RF tag, which is information necessary to identify the performance of the RF tag, and that adjusts the transmission power, etc. of the gate-type reader used when the outer box passes through the gate-type reader according to the information read by the IC information reader (Patent Document 2).

[0007] JP 2016-62160 A JP 2020-109584 A

[0008] The present invention has been made in view of the above-mentioned background art, and has an object to provide an information reading device that prevents unintended reading of RFID tags and improves reading accuracy.

[0009] In order to achieve the above object, the information reading device of the present invention comprises an RFID reader main body and an RFID antenna connected to the RFID reader main body, and sets an RSSI filter value for each RFID tag based on tag data recorded in the RFID tag read by the RFID reader main body.

[0010] According to the information reading device, the RSSI filter value is set for each RFID tag based on the tag data recorded in the RFID tag read by the RFID reader main body, making it possible to set the sensitivity for each RFID tag and increasing the accuracy of reading the intended RFID tag.

[0011] In a specific embodiment, tag data may be identified from an RFID tag, and an RSSI filter value may be set for each type of RFID tag. In this case, for example, RFID tags with different sensitivities may be detected within a similar distance range.

[0012] FIG. 1 is a conceptual diagram illustrating an RFID system including an information reading device according to an embodiment. FIG. 2 is a block diagram illustrating the circuit configuration of the information reading device. FIG. 3 is a conceptual diagram illustrating an RFID tag to be detected by the information reading device. FIG. 4A is a diagram illustrating the setting of an RSSI filter in the information reading device. FIG. 4B is a conceptual diagram specifically illustrating the contents of the RSSI filter. FIG. 4C is a conceptual diagram illustrating a modified example of the RSSI filter. FIG. 5 is a diagram illustrating an example of the operation of an information reading device, etc. FIG. 6 is a diagram illustrating another application example of the information reading device. FIG. 7 is a diagram illustrating a modified example of an information reading device, etc.

[0013] Hereinafter, an RFID system including an information reading device according to the present invention will be described with reference to FIG.

[0014] The RFID system 100 includes a gate device 110 that is arranged on either side of an aisle PW and checks the passage of an object, and an upper-level management device 30 that manages the gate device 110. In this embodiment, the gate device 110 functions as an information reading device 10. The information reading device 10 includes a main gate member 10a and a sub-gate member 10b. The area above the aisle PW, sandwiched between the main gate member 10a and the sub-gate member 10b, is a reading area DA, which is a monitored zone that individually detects the passage of RFID tags TG1 and TG2 attached to multiple objects OB1 and OB2. The main gate member 10a is directly connected to the upper-level management device 30, and the sub-gate member 10b is connected to the main gate member 10a via a cable CA.

[0015] FIG. 2 is a block diagram illustrating the gate device 110, i.e., the information reading device 10. The information reading device 10 is assumed to operate in the UHF band, for example. In the information reading device 10, the main gate member 10a includes an RFID reader / writer main body 21, an RFID antenna 23 indirectly connected to the RFID reader / writer main body 21, an antenna switch 24 interposed between the RFID reader / writer main body 21 and the RFID antenna 23, and a control device 25 that controls the overall operation. The RFID reader / writer main body 21, the RFID antenna 23, the antenna switch 24, and the control device 25 are incorporated into a case 10f, which is a single housing. In this case, the case 10f and its interior can be used as a gate member. The main gate member 10a further includes a first infrared light source 27a and a second infrared light source 28a that operate under the control of the control device 25. The sub-gate member 10b includes an RFID antenna 23, and further includes a first infrared sensor 27b and a second infrared sensor 28b.

[0016] The RFID reader / writer main body 21 is an RFID reader main body 121 in terms of its reading function. The RFID reader / writer main body 21 has a control circuit 21a including a CPU 21c and a memory 21m, and operates based on an installed program. The control circuit 21a functions as an RSSI filter AF, which will be described later. The RFID reader / writer main body 21 supplies power to the RFID antenna 23, outputs radio waves in a predetermined band (specifically, for example, UHF radio waves of 860 to 960 MHz), receives response waves from the RFID tags TG1 and TG2 passing through the passage PW, identifies the RFID tags TG1 and TG2, obtains necessary information from the RFID tags TG1 and TG2, and writes information to the RFID tags TG1 and TG2 as necessary.

[0017] More specifically, (1) the RFID reader / writer main body 21 transmits radio waves, which are carrier waves carrying commands, from the RFID antenna 23. (2) The RFID tags TG1 and TG2 receive the radio waves from the RFID reader / writer main body 21, i.e., the RFID antenna 23, causing current to flow through the RFID tags TG1 and TG2, converting the information in the tag chip into a signal in response to the command from the RFID reader / writer main body 21. (3) The RFID tags TG1 and TG2 transmit a response signal from the tag antenna. (4) The RFID reader / writer main body 21 receives the response signal via the RFID antenna 23. The response signal obtained in this manner is subjected to data processing by the RFID reader / writer main body 21 and the control device 25. At this time, commands from the RFID reader / writer main body 21 enable operations such as read, write, and anti-collision. The RFID reader / writer main body 21 also has a function of monitoring the received signal strength of the response waves from the RFID tags TG1 and TG2, that is, the RSSI (Received Signal Strength Indicator).

[0018] The RFID antenna 23 incorporated in the main gate member 10a may include a single antenna, or may include multiple antenna elements, with the operation timing of each antenna element switched, for example, in a time series. The RFID antenna 23 incorporated in the sub-gate member 10b is similar to the RFID antenna 23 incorporated in the main gate member 10a.

[0019] The antenna switch 24 operates under the control of the RFID reader / writer main body 21, and connects either the RFID antenna 23 of the main gate member 10a or the RFID antenna 23 of the sub-gate member 10b to the RFID reader / writer main body 21. In other words, the RFID antenna 23 incorporated in the sub-gate member 10b operates at a different timing from the RFID antenna 23 incorporated in the main gate member 10a.

[0020] The control device 25 is a controller 22 configured, for example, by a microcomputer. The control device 25 has a CPU 25a, a memory 25b, a communication circuit 25c, etc., and operates based on an installed program. The control device 25 manages the operating states of the RFID reader / writer main body 21, the infrared light sources 27a, 28a, and the infrared sensors 27b, 28b. However, the control device 25 does not need to be independent from the RFID reader / writer main body 21 and can be incorporated into the RFID reader / writer main body 21 as a function of the control circuit 21a of the RFID reader / writer main body 21. The control device 25 may be a function realized by the computer of the host management device 30 shown in FIG. 1. In this case, the RFID reader / writer main body 21 is directly managed by the host management device 30.

[0021] The first infrared light source 27a and the second infrared light source 28a are fixed to a case 10f, which is the housing of the main gate member 10a shown in Figure 1, and the first infrared sensor 27b and the second infrared sensor 28b are fixed to a case 10f of the sub-gate member 10b.

[0022] The first infrared light source 27a operates under the control of the control device 25 and emits light continuously or periodically. The first infrared sensor 27b detects infrared light emitted from the first infrared light source 27a. The control device 25 detects the passage of a person or the like based on the detection result of the first infrared sensor 27b. In the above, the first infrared light source 27a and the first infrared sensor 27b function as a first human detection infrared module 27 that detects a person passing through the reading area DA. The second infrared light source 28a operates under the control of the control device 25 and emits light continuously or periodically. The second infrared sensor 28b detects infrared light emitted from the second infrared light source 28a. The control device 25 detects the passage of a person or the like based on the detection result of the second infrared sensor 28b. In the above, the second infrared light source 28a and the second infrared sensor 28b function as a second human detection infrared module 28 that detects a person passing through the reading area DA. When the first human detection infrared module 27 first detects the passage of a relatively large object, and then the second human detection infrared module 28 detects the passage of a relatively large object, the control device 25 can determine the passage of a person or object moving forward along the passage PW. That is, the control device 25 performs the passage determination by combining the passage determination of objects OB1 and OB2 using RFID tags TG1 and TG2 with the passage detection of a person using the human detection infrared modules 27 and 28. Specifically, when the control device 25 determines passage using RFID tags TG1 and TG2 and also determines passage using the human detection infrared modules 27 and 28, it determines that a person carrying the RFID tag TG1 or TG2 has passed through the reading area DA. In this case, the passage detection by the human detection infrared modules 27 and 28 can be used as an auxiliary to increase the reliability of the determination.

[0023] The information reading device 10 may be provided with an alarm including a speaker and a lamp. When the RFID reader / writer main body 21 determines that the RFID tags TG1 and TG2 are present, the alarm receives a command from the control device 25 and performs an alarm process using audio or visual effects regarding the detection of the RFID tags TG1 and TG2.

[0024] FIG. 3 is a conceptual diagram illustrating an RFID tag TG1 to be detected by the information reading device 10. The RFID tag TG1 includes an antenna 71 and an IC chip 72. The memory 72a of the IC chip 72 includes four memory areas: (1) EPC (UII) memory 73a, (2) TID memory 73b, (3) USER memory 73c, and (4) RESERVED memory 73d. The tag type can be determined at various levels from all or part of the tag data stored in, for example, the TID memory 73b. However, instead of the TID memory 73b, the tag type may also be determined from the tag data stored in the EPC memory 73a or the USER memory 73c. ​​Because the EPC memory 73a and the USER memory 73c can be freely read and written by the user, these areas can be used to determine the type of RFID tag, and RFID tags of the same type can be distinguished based on appropriate criteria. Specifically, it is possible to distinguish between tags with different uses and response characteristics, for example. By distinguishing between tags with different uses and response characteristics in this way, it becomes possible to detect individual RFID tags according to their purpose and characteristics.

[0025] 4A is a chart for explaining the settings of the RSSI filter AF in the information reading device 10. The RSSI filter AF is realized by the control circuit 21a.

[0026] In the chart shown, the horizontal axis represents the distance (m) from the RFID antenna 23, and the vertical axis represents the RSSI (dBm). The RFID tag TG1, which is a low-sensitivity IC tag, has sensitivity or response characteristics as shown by the solid line, and the RFID tag TG2, which is a high-sensitivity IC tag, has sensitivity or response characteristics as shown by the dotted line.

[0027] That is, when the RFID tags TG1 and TG2 are present in approximately the same distance range (for example, when they are both separated by a distance of about D1), the RFID reader / writer main body 21 receives a stronger response wave or radio wave from the RFID tag TG2 than from the RFID tag TG1. Specifically, when both RFID tags TG1 and TG2 are separated by a distance of 1 m from the RFID antenna 23, the RSSI of the received wave from the low-sensitivity RFID tag TG1 is −60 dBm, while the RSSI of the received wave from the high-sensitivity RFID tag TG2 is −52 dBm, resulting in a large difference.

[0028] On the other hand, even if the high-sensitivity RFID tag TG2 is much farther away than the low-sensitivity RFID tag TG1 (for example, if the distance between RFID tag TG1 and RFID tag TG2 is D1 and D2, respectively, and D1<D2), the RFID reader / writer main body 21 receives response waves or radio waves of the same magnitude from both RFID tags TG1 and TG2. Specifically, when one RFID tag TG1 is 1 m away from the RFID antenna 23 and the other RFID tag TG2 is 2.5 m away from the RFID antenna 23, the RSSI of the received waves from both RFID tags TG1 and TG2 is -60 dBm, which is the same.

[0029] Therefore, in the information reading device 10 of this embodiment, the filter value (hereinafter also referred to as the filter value) of the RSSI filter AF, i.e., the lower limit RSSI value when detecting the RFID tags TG1 and TG2, is set to, for example, −60 dBm for one RFID tag TG1 and −52 dBm for the other RFID tag TG2. This allows the RFID tags TG1 and TG2, which have different sensitivities, to be detected approximately equally when they are within the same distance range, i.e., within 1 m of the RFID antenna 23.

[0030] 4B is a conceptual diagram specifically explaining the contents of the RSSI filter AF. In the illustrated example, for example, M types (M is a natural number) of tag types No. 1 to M are assumed as RFID tags, and the lower limit RSSI value of detection is set as the filter value for each. This allows M types of RFID tags to be detected approximately equally within the same distance range. Note that when distinguishing among RFID tags of the same type, a filter condition column (e.g., 1-1 or 1-2) is added for one or more specific tag types, and a filter value is set for each filter condition (see FIG. 4C).

[0031] FIG. 5 is a flowchart illustrating the operation of the information reading device 10. The control circuit 21a of the RFID reader / writer main body 21 attempts to read RFID tags TG1 and TG2 (step S11). The control circuit 21a then determines whether the RSSI value of the received signal from the read RFID tag is equal to or greater than a common setting (step S12). If the RSSI value is less than the common setting (No in step S12), the control circuit 21a discards the acquired tag data for that RFID tag (step S13) and terminates processing. The common setting is set when a "common RSSI filter setting" that does not distinguish between RFID tag types is enabled, and refers to a common lower limit for the RSSI value when detecting RFID tags. In contrast to the "common RSSI filter setting," the "individual RSSI filter setting" distinguishes between RFID tag types and enables each RFID tag to be detected approximately equally within a similar distance range. The "individual RSSI filter setting" is designed for tag type No. 10, for example.

[0032] If the answer is Yes in step S12, the control circuit 21a determines whether the ``individual RSSI filter setting'', i.e., the individual RSSI filter, is valid (step S14).If the individual RSSI filter is not valid (No in step S14), it assumes that RFID tags that show an RSSI value equal to or greater than the common setting value have been effectively detected using the ``common RSSI filter setting'', and transmits the acquired tag data to the control device 25 or the higher-level management device 30 (step S15), and ends the processing.

[0033] If any of the individual RSSI filters is enabled (Yes in step S14), the control circuit 21a selects one of the masking conditions from one or more set masking conditions (step S16). The masking conditions may be set to distinguish between tag types (see FIG. 4B), but they may also be set to distinguish between tags of the same type based on their intended use, i.e., filter conditions (see FIG. 4C). Here, intended use refers to, for example, a case where the same type of tag is attached to two targets (e.g., targets A and B), and target A is to be read from nearby while target B is to be read from a distance. The control circuit 21a determines whether the information in the read tag data (e.g., TID data) matches the specified information (step S17). If the read information matches the specified information (hereinafter referred to as "if the masking conditions match"), it determines whether the RSSI value at the time of reading is equal to or greater than the filter value of the individual RSSI filter (hereinafter referred to as "individual threshold value") (step S18). If the RSSI value at the time of reading is equal to or greater than the individual threshold, the control circuit 21a transmits the acquired tag data to the control device 25 or the higher-level management device 30 (step S19). If the RSSI value at the time of reading is less than the individual threshold, the control circuit 21a discards the acquired tag data for the RFID tag (step S20). The control circuit 21a then checks whether all masking conditions for possible tag types have been specified (step S21). Even if the answer to step S17 is No, the control circuit 21a checks whether all masking conditions have been specified. If the result of the check is that all masking conditions have not been specified (No in step S21), the control circuit 21a returns to step S16 and specifies the next masking condition (e.g., tag type). Through the above process, if there are multiple RFID tags of the same tag type, these can be extracted all at once.

[0034] In the above, the tag type etc. is specified in step S16, but it is also possible to specify a classification or category based on a different standard than the tag type recorded on the RFID tag. In this case, it becomes possible to extract only RFID tags of a specific classification of interest.

[0035] Although not explained above, if the mask conditions are not met for all possible tag types, the tag data that do not meet the conditions may be discarded and the process may end, or the tag data that do not meet the conditions may be sent to the control device 25 or the higher-level management device 30. The method of doing either can be switched by setting the operation program of the control circuit 21a.

[0036] 6 is a diagram illustrating an information reading device 210, which is a modification of the information reading device 10 shown in FIG. In this example, multiple bookshelves BS1 and BS2 store a large number of books BO. One bookshelves BS1 has a first RFID antenna AT1 embedded therein, and stores a low-sensitivity book group G11 consisting of multiple books BO with low-sensitivity RFID tags TG1 and a high-sensitivity book group G12 consisting of multiple books BO with high-sensitivity RFID tags TG2. The other bookshelves BS2 has a second RFID antenna AT2 embedded therein, and stores a low-sensitivity book group G21 consisting of multiple books BO with low-sensitivity RFID tags TG1 and a high-sensitivity book group G22 consisting of multiple books BO with high-sensitivity RFID tags TG2. In other words, the RFID antennas AT1 and AT2 are attached to shelves that store items.

[0037] The RFID antennas AT1 and AT2 are powered by the RFID reader / writer main body 221 and output received signals to the RFID reader / writer main body 221. The RFID reader / writer main body 221 has the same structure as the RFID reader / writer main body 21 shown in Fig. 1, and therefore a description thereof will be omitted.

[0038] In the information reading device 10 described above, if an individual RSSI filter is set, the detection sensitivity is adjusted based on the filter value or the lower limit RSSI value, so that only the low-sensitivity book group G11 and the high-sensitivity book group G12, whose distance from the first RFID antenna AT1 is appropriately set, are selectively detected, and only the low-sensitivity book group G21 and the high-sensitivity book group G22, whose distance from the second RFID antenna AT2 is appropriately set, are selectively detected. In other words, not only can tag data not be overlooked, but interference between bookshelves BS1 and BS2, i.e., misreading of tag data, can be avoided. In addition, from the perspective of controlling the reading area, it is also possible to set not only the lower limit RSSI value but also the upper limit RSSI value as the filter value, and set the RSSI value to an appropriate zone.

[0039] FIG. 7 is a diagram illustrating another modified information reading device 310. In this case, the information reading device 310 includes a gate device 110 and a host management device 30. The gate device 110 has a structure similar to that shown in FIG. 1 , except that the gate device 110 does not include an RSSI filter, as described below. The host management device 30 also includes a control unit 31, a memory unit 32, an input / output unit 33, and a communication unit 34. The control unit 31 operates based on a program stored in the memory unit 32, performs processing based on information obtained from the input / output unit 33 and the communication unit 34, and stores the progress and results of the processing in the memory unit 32 and presents them to the input / output unit 33. The control unit 31 also communicates with the gate device 110 via the communication unit 34 based on the program, etc., to manage the operation of the RFID reader / writer main unit 21 and the control device 25 of the gate device 110. In this case, the host management device 30 is provided with an RSSI filter setting function or the RSSI filter itself. In this case as well, by setting an appropriate RSSI value for each of the RFID tags TG1 and TG2, the RFID tags TG1 and TG2 with different sensitivities can be detected within approximately the same distance range.

[0040] The information reading devices 10, 210, 310 of the embodiments described above include an RFID reader / writer main body 21, 221 and an RFID antenna 23, AT1, AT2 connected to the RFID reader / writer main body 21, 221, and set an RSSI filter value for each RFID tag TG1, TG2 based on the tag data recorded in the RFID tags TG1, TG2 read by the RFID reader / writer main body 21, 221.

[0041] According to the above-mentioned information reading device, the RSSI filter value is set for each RFID tag TG1, TG2 based on the tag data recorded in the RFID tags TG1, TG2 read by the RFID reader / writer main body 21, 221, making it possible to set the sensitivity for each RFID tag TG1, TG2, thereby increasing the accuracy of reading the intended RFID tags TG1, TG2.

[0042] Although the present invention has been described above based on the embodiments, the present invention is not limited to the above embodiments. While the above describes a method of setting RFID tags TG1 and TG2 with different sensitivities to be detected at approximately the same distance, the present invention is not limited to this example, and the RSSI filter value can also be set to detect RFID tags with similar sensitivities at different distances. For example, if it is assumed that RFID tags with similar sensitivities are located in different areas, such an RSSI filter setting is necessary.

[0043] The information reading device 10 enables management of taking out books from a library, for example, but is not limited to this.

Claims

1. An information reading device comprising: an RFID reader body; and an RFID antenna connected to the RFID reader body; and which sets an RSSI filter value for each RFID tag based on tag data recorded in the RFID tag read by the RFID reader body.

2. The information reading device according to claim 1, wherein the RSSI filter has a plurality of filter conditions and an RSSI filter value for each of the filter conditions.

3. The information reading device according to claim 1, wherein the RFID tag is one of a plurality of types of RFID tags expected to be used, and the value of the RSSI filter is set for each type of RFID tag based on the tag data.

4. The information reading device according to claim 1, wherein the data used to identify the tag data is stored in one of the TID memory, EPC memory, and USER memory.

5. The information reading device according to claim 1, wherein the value of the RSSI filter is set so as to detect RFID tags with different sensitivities at approximately the same distance.

6. The information reading device according to claim 1, wherein the value of the RSSI filter is set so as to detect RFID tags with equivalent sensitivity at different distances.

7. The information reading device according to any one of claims 1 to 6, wherein the RFID antenna is provided in association with a gate device.

8. An information reading device according to any one of claims 1 to 6, wherein the RFID antenna is attached to a shelf that stores items.

9. The information reading device according to any one of claims 1 to 6, wherein the RSSI filter is incorporated into the RFID reader body.

10. An information reading device according to any one of claims 1 to 6, wherein the RSSI filter is incorporated into a host management device that manages the operation of the RFID reader main body.

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