Wireless tag reader and program

Abstract

To provide a wireless tag reader and a program configured to ensure high speed and accuracy in reading a large number of wireless tags.SOLUTION: An RFID tag reader (wireless tag reader) includes: a first read unit (first read means) for reading information held by an RFID tag (wireless tag); a second read unit (second read means) for reading the information held by the RFID tag with higher accuracy than the first read unit; a Q value adjustment unit (adjustment means) for adjusting a Q value related to reading the RFID tag, in accordance with a response status of the RFID tag, when the first read unit or the second read unit is configured to prevent an RFID tag read once from making a response for a predetermined time or longer; and a read method switching unit (switching means) for switching the first read unit and the second read unit to read the RFID tag in accordance with a magnitude relation between the Q value and a switching threshold (threshold).SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] An embodiment of the present invention relates to a wireless tag reader and a program. [Background technology]

[0002] BACKGROUND ART Conventionally, inventory management of items to which wireless tags such as RFID (Radio Frequency Identification) tags are attached has been carried out by reading data (hereinafter also referred to as tag data) stored in the wireless tags using a wireless tag reader.

[0003] Inventory management is performed by reading a large number of wireless tags at once. RFID tag reading protocols include the FM0 method, which has high reading speed but low receiving sensitivity and a short reading distance, and the mirror subcarrier method, which is not as fast as the FM0 method but has high receiving sensitivity and a long reading distance. For example, Patent Document 1 discloses a wireless tag reader using the FM0 method, and Patent Document 2 discloses a wireless tag reader using the mirror subcarrier method. Thus, conventionally, reading was performed by selecting either the FM0 method or the mirror subcarrier method.

[0004] When using the FM0 method to read a large number of RFID tags, it was possible to read them quickly, but there was a possibility that RFID tags at the back of the shelf would not be read. Also, when using the FM0 method to read the RFID tags of many products packed tightly together in an Oricon (foldable container), there was a possibility that reading would not be possible due to low reception sensitivity. On the other hand, when using the mirror subcarrier method, reading would not be possible very often, but reading was slower than with the FM0 method. Summary of the Invention [Problem to be solved by the invention]

[0005] The problem to be solved by the present invention is to provide a radio tag reader and a program that can achieve both high reading speed and high reading accuracy when reading a large number of radio tags. [Means for solving the problem]

[0006] The RFID tag reader of the embodiment includes a first reading unit, a second reading unit, an adjustment unit, and a switching unit. The first reading unit reads information stored in the RFID tag. The second reading unit reads information stored in the RFID tag with higher accuracy than the first reading unit. The adjustment unit , th 1 reading means and is the When the reading means of the second embodiment is used with a setting that prevents a wireless tag that has been read once from responding for a predetermined period of time or more, the reading means adjusts the Q value for reading the wireless tag according to the response status of the wireless tag. but Threshold If the Q value is equal to or greater than the threshold, the first reading means reads the wireless tag, and if the Q value is less than the threshold, the second reading means reads the wireless tag. The wireless tag is read. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a diagram illustrating an example of a configuration of an RFID tag reader according to an embodiment. [Figure 2] FIG. 2 is a hardware block diagram showing an example of a hardware configuration of an RFID tag reader according to an embodiment. [Figure 3A] FIG. 3A is a diagram illustrating the FM0 method, which is an example of the first reading means. [Figure 3B] FIG. 3B is a diagram illustrating a mirror sub-scanning method, which is an example of the second reading means. [Figure 4] FIG. 4 is a functional block diagram illustrating an example of a functional configuration of an RFID tag reader according to an embodiment. [Figure 5A] FIG. 5A is a flowchart showing an example of the flow of processing performed by the RFID tag reader according to the embodiment. [Figure 5B] FIG. 5B is a flowchart showing an example of the flow of a reading process using the FM0 method. [Figure 5C] FIG. 5C is a flowchart showing an example of the flow of a reading process using the MS method. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, a radio tag reader and a program according to an embodiment will be described with reference to the drawings. The following describes an RFID tag reader 10 that reads an RFID tag, which is an example of a radio tag. Note that the present invention is not limited to the embodiments described below.

[0009] (Overview of the wireless tag reader) An overview of an RFID tag reader 10 will be described with reference to Fig. 1. Fig. 1 is a diagram showing an example of the configuration of an RFID tag reader according to an embodiment.

[0010] The RFID tag TG is attached to an item G, such as a product, and stores tag data in a storage medium (not shown). The tag data includes a tag identifier that can identify the RFID tag TG itself, an item identifier that can identify the type of item G to which the RFID tag TG is attached, and the like.

[0011] The RFID tag reader 10 of this embodiment is a handheld type wireless tag reader that can be carried by an operator. For example, the RFID tag reader 10 is pointed by the operator toward a shelf or the like on which articles G are placed, and reads tag data from the RFID tag TG attached to each of the articles G. The RFID tag reader 10 is an example of a wireless tag reader in the present disclosure. The RFID tag TG is an example of a wireless tag in the present disclosure.

[0012] (Hardware configuration of wireless tag reader) The hardware configuration of the RFID tag reader 10 will be described with reference to Fig. 2. Fig. 2 is a hardware block diagram showing an example of the hardware configuration of the RFID tag reader according to the embodiment.

[0013] 2, the RFID tag reader 10 includes a CPU 11, a ROM 12, a RAM 13, a storage unit 14, etc. The CPU 11 is an example of a processor, and controls the overall operation of the RFID tag reader 10. The ROM 12 stores various programs. The RAM 13 is used as a working memory for expanding various data. The RAM 13 also holds a read buffer for storing tag data read from the RFID tag TG.

[0014] The CPU 11, ROM 12, RAM 13, and storage unit 14 are connected via a bus or the like. Here, the CPU 11, ROM 12, and RAM 13 constitute a control unit 100. The control unit 100 executes a control process, which will be described later, by the CPU 11 loading a control program stored in the ROM 12 or storage unit 14 into the RAM 13 and executing it.

[0015] The storage unit 14 is configured with a nonvolatile memory such as a flash memory that retains stored information even when the power is turned off. The storage unit 14 stores a control program P and an item master M.

[0016] The control program P is a program for enabling the RFID tag reader 10 to perform its functions. The control program P may be provided by being pre-installed in the ROM 12. The control program P may also be provided by being recorded on a computer-readable recording medium such as a CD-ROM, a flexible disk (FD), a CD-R, or a DVD in a format that can be installed or executed by the control unit 100. The control program P may also be provided by being stored on a computer connected to a network such as the Internet and downloaded via the network. The control program P may also be provided or distributed via a network such as the Internet.

[0017] The item master M is a master file that stores information (item code, product name, price, etc.) about items that are the subject of inventory management.

[0018] Furthermore, a peripheral device controller 15 and a communication interface 20 are connected to the control unit 100 via a bus or the like. A display device 16, an operation device 17, a reading unit 18, and a buzzer 19 are connected to the peripheral device controller 15.

[0019] The display device 16 is formed of, for example, a liquid crystal panel, and displays various information to the operator.

[0020] The operation device 17 has input devices such as various operation buttons and a touch panel, and receives operations from an operator.

[0021] The reading unit 18 has an antenna 181, a transmitting unit 182, and a receiving unit 183. The transmitting unit 182 supplies power to the antenna 181 for emitting radio waves from the antenna 181. The receiving unit 183 receives radio waves transmitted from the RFID tag TG via the antenna 181. Under the control of the control unit 100, the reading unit 18 emits radio waves for reading the RFID tag TG and receives radio waves emitted by the wireless tag that has received the radio waves, thereby reading tag data stored in the RFID tag TG.

[0022] When the control unit 100 reads a new RFID tag TG, the buzzer 19 sounds in response to an instruction from the control unit 100. When the operator of the RFID tag reader 10 confirms that the buzzer 19 has stopped sounding, he or she recognizes that a new RFID tag TG is not being read. Then, the operator of the RFID tag reader 10 changes the reading range by moving the position of the RFID tag reader 10, and continues reading the RFID tag TG.

[0023] The communication interface 20 is a communication interface that complies with wireless communication standards such as Bluetooth (registered trademark), wireless LAN, etc. Under the control of the control unit 100, the communication interface 20 performs wireless communication with external devices such as a mobile terminal or a server device, which are not shown in FIG.

[0024] (Reading tag data using the FM0 method) Reading tag data using the FM0 method will be described with reference to Fig. 3A. Fig. 3A is a diagram illustrating the FM0 method, which is an example of the first reading means.

[0025] The FM0 (Frequency Modulation 0) method is a method in which an RFID tag TG that receives a transmission wave S replies at the same frequency fc as the transmission wave S, and the RFID tag reader 10 reads the reply wave R. More specifically, when the RFID tag TG receives the transmission wave S transmitted from the antenna 151, it converts the energy of the received transmission wave S into power and is activated by that power. Then, the RFID tag TG analyzes the command contained in the transmission wave S and generates a reply wave R at the same frequency as the transmission wave S, which includes a response according to the command. The RFID tag TG then replies with the generated reply wave R.

[0026] With the FM0 method, the RFID tag TG only needs to respond at the same frequency fc as the transmission wave S, resulting in a short response time. In other words, the RFID tag TG can send back a response wave R at high speed. On the other hand, with the FM0 method, the frequencies of the transmission wave S and the response wave R are the same, resulting in low reception sensitivity and a short reading distance. Therefore, the FM0 method is suitable for applications where a large number of RFID tags TG in a short distance must be read at high speed.

[0027] (Tag data reading using mirror sub-scan method) Reading tag data using the mirror sub-scanning method will be described with reference to Fig. 3B, which is a diagram illustrating the mirror sub-scanning method, which is an example of the second reading means.

[0028] The mirror subcarrier method (hereinafter referred to as the MS method) is a method in which an RFID tag TG that receives a transmission wave S creates a subcarrier component, replies with a response wave R in which the subcarrier is modulated with a response data signal, and an RFID tag reader 10 reads the response wave R. Therefore, in the MS method, the RFID tag TG replies with the response wave R at frequencies fa and fb that are different from the frequency fc of the transmission wave S, i.e., at a different channel.

[0029] With the MS method, the RFID tag TG responds at frequencies fa and fb that are different from the frequency fc of the transmission wave S, which improves receiving sensitivity compared to the FM0 method, thereby enabling a longer reading distance compared to the FM0 method. On the other hand, since it is necessary to create a response wave R modulated with a response data signal, the response speed is slower than with the FM0 method. Therefore, the MS method is more suitable than the FM0 method for applications where a large number of RFID tags TG located at a long distance must be read at a slow speed with high accuracy.

[0030] (Functional configuration of the wireless tag reader) The functional configuration of the RFID tag reader 10 will be described with reference to Fig. 4. Fig. 4 is a functional block diagram showing an example of the functional configuration of the RFID tag reader according to the embodiment.

[0031] The control unit 100 of the RFID tag reader 10 loads the control program stored in the ROM 12 or the storage unit 14 into the RAM 13 and runs it, thereby realizing the first reading unit 21, the second reading unit 22, the Q-value adjustment unit 23, the reading method switching unit 24, the threshold setting unit 25, the reading result registration unit 26, and the reading control unit 27 as functional units shown in Fig. 4. Note that each of these functions may be configured by hardware such as a dedicated circuit.

[0032] The first reading unit 21 reads information held by an RFID tag TG from the RFID tag TG present inside the communication area of ​​the antenna 151. The first reading unit 21 is an example of the first reading means in the present disclosure. The first reading unit 21 reads information held by the RFID tag TG, for example, using the FMO method.

[0033] The second reading unit 22 reads information held by an RFID tag TG present inside the communication area of ​​the antenna 151 with higher reading accuracy than the first reading unit 21. The second reading unit 22 is an example of the second reading means in the present disclosure. The second reading unit 22 reads information held by the RFID tag TG, for example, by the MS method.

[0034] The Q-value adjusting unit 23 adjusts the Q-value related to reading the RFID tag TG according to the response state of the RFID tag TG. The Q-value adjusting unit 23 is an example of an adjusting means in the present disclosure.

[0035] The RFID tag reader 10 is equipped with an anti-collision function using a time slot method (slot aloha method) to read a large number of RFID tags TG without omission. The RFID tag reader 10 with the time slot method reads specific bits (1 to 2) defined by a Q value for RFID tags TG present within the communication area of ​​the antenna 181. Q :Q is an integer greater than or equal to 1) as the slot.

[0036] The RFID tag TG that has received the slot specification generates a random number within the range of the specified number of bits. For example, if the slot is 2 bits (Q=1), the RFID tag TG generates one of the 2-bit random numbers "00," "01," "10," or "11." Then, only the RFID tag TG that has generated a random number that matches the random number specified by the RFID tag reader 10 returns a response to the RFID tag reader 10.

[0037] At this time, if only one RFID tag TG returns a response to one slot, the RFID tag reader 10 receives the tag data of that RFID tag TG as the read result. On the other hand, if multiple RFID tags TG generate the same random number, multiple RFID tags TG will simultaneously return responses to one slot. In such a case, the RFID tag reader 10 determines that a collision has occurred and does not receive the tag data.

[0038] The RFID tag TG in which a collision occurred generates a random number again and returns a response to the RFID tag reader 10 using the slot with the timing that matches the generated random number. Thereafter, the RFID tag reader 10 repeats the reading process until only one tag data is read for each slot, thereby avoiding collisions. At this time, the Q-value adjustment unit 23 automatically adjusts the Q-value according to the response status of the RFID tag TG. Specifically, the Q-value adjustment unit 23 automatically adjusts the Q-value according to whether the response from the RFID tag TG is appropriate for the number of slots, whether there are many responses from the RFID tag TG for the number of slots, or whether there are few responses from the RFID tag TG for the number of slots.

[0039] For example, when the number of RFID tags TG is about 800, the RFID tag reader 10 sets the initial value of the Q factor to 10 to 11 (1024 (=2 10 )~2048(=2 11 )), theoretically, all RFID tags TG can be read. In this way, the Q value is adjusted to be larger when a large number of RFID tags TG are to be read at one time, and the Q value is adjusted to be smaller when a small number of RFID tags TG are to be read at one time. More specifically, for example, if a collision occurs, the Q value adjustment unit 23 adjusts the Q value to a larger value and repeats reading until all RFID tags TG can be read. Furthermore, if no collision occurs, i.e., if the number of no-response slots is large, the Q value adjustment unit 23 adjusts the Q value to a smaller value.

[0040] The RFID tag reader 10 specifies the state of the inventory flag of the RFID tag TG (no response, responded) so that the RFID tag TG that has been successfully read does not participate in reading again for a predetermined period of time. For example, by specifying session 2 or session 3, the RFID tag TG that has responded can be prevented from sending back a response wave R for at least two seconds. By using this function, the RFID tag reader 10 prevents receiving the response wave R from the same RFID tag TG multiple times.

[0041] The reading method switching unit 24 switches between the first reading unit 21 and the second reading unit 22 to read the RFID tag TG depending on the magnitude relationship between the Q value adjusted by the Q value adjusting unit 23 and a switching threshold Th, which is a threshold value for the Q value described below. The reading method switching unit 24 is an example of a switching means in the present disclosure. The switching threshold Th is an example of a threshold in the present disclosure.

[0042] The threshold setting unit 25 sets a switching threshold Th, which is a threshold of the Q value used when the reading method switching unit 24 determines whether to switch the reading method for the RFID tag TG. The threshold setting unit 25 is an example of a setting means in the present disclosure. The threshold setting unit 25 sets the switching threshold Th based on, for example, operation information of the operator of the RFID tag reader 10.

[0043] The read result registration unit 26 registers the read result of the first reading unit 21 or the second reading unit 22.

[0044] The read control unit 27 instructs the start and end of the read process performed by the RFID tag reader 10. The read control unit 27 also sets the initial value of the Q value.

[0045] (Processing flow performed by a wireless tag reader) The flow of processing performed by the RFID tag reader 10 will be described with reference to Fig. 5A. Fig. 5A is a flowchart showing an example of the flow of processing performed by the RFID tag reader according to the embodiment.

[0046] The reading control unit 27 determines whether the operator of the RFID tag reader 10 has issued an instruction to start reading via the operation device 17 (step S11). If it is determined that an instruction to start reading has been issued (step S11: Yes), the process proceeds to step S12. On the other hand, if it is not determined that an instruction to start reading has been issued (step S11: No), step S11 is repeated.

[0047] If it is determined in step S11 that a reading start instruction has been issued, the threshold setting unit 25 sets a switching threshold Th (step S12).

[0048] The reading control unit 27 sets an initial value of the Q value (step S13). The reading control unit 27 sets the initial value of the Q value based on operation information of the operator of the RFID tag reader 10, for example.

[0049] The reading method switching unit 24 determines whether the Q value is equal to or greater than the switching threshold value Th (step S14). If it is determined that the Q value is equal to or greater than the switching threshold value Th (step S14: Yes), the process proceeds to step S15. On the other hand, if it is not determined that the Q value is equal to or greater than the switching threshold value Th (step S14: No), the process proceeds to step S16.

[0050] If it is determined in step S14 that the Q value is equal to or greater than the switching threshold value Th, the first reading unit 21 performs reading processing using the FM0 method (step S15). Then, the process proceeds to step S17. The flow of processing performed in step S15 will be described in detail later (see FIG. 5B).

[0051] If it is determined in step S14 that the Q value is not equal to or greater than the switching threshold value Th, the second reading unit 22 performs reading processing using the MS method (step S16). Then, the process proceeds to step S17. The flow of processing performed in step S16 will be described in detail later (see FIG. 5C).

[0052] Following step S15 or step S16, the reading control unit 27 determines whether the operator of the RFID tag reader 10 has issued an instruction to stop reading via the operation device 17 (step S17). If it is determined that an instruction to stop reading has been issued (step S17: Yes), the RFID tag reader 10 ends the processing of Fig. 5A. On the other hand, if it is not determined that an instruction to stop reading has been issued (step S17: No), the processing returns to step S14.

[0053] The RFID tag reader 10 sounds a buzzer 19 (see FIG. 2) when it reads a new RFID tag TG. If the frequency of the buzzer 19 sounds is high, the operator of the RFID tag reader 10 continues reading without moving the RFID tag reader 10. If the frequency of the buzzer 19 sounds decreases, that is, if the number of new RFID tags TG that can be read decreases, the operator moves the RFID tag reader 10 up, down, left, or right, or moves himself or herself. In this way, the RFID tag reader 10 can, for example, take an inventory of the items G on an entire shelf.

[0054] (Reading flow using the FM0 method) The flow of the reading process according to the FM0 method performed by the first reading unit 21 will be described with reference to Fig. 5B. Fig. 5B is a flowchart showing an example of the flow of the reading process according to the FM0 method.

[0055] The Q value adjustment unit 23 adjusts the Q value related to reading the RFID tag TG according to the response state of the RFID tag TG (step S21).

[0056] The first reading unit 21 reads the information held by the RFID tag TG by the FMO method (step S22). When reading the information held by the RFID tag TG, the above-mentioned time slot method is used.

[0057] The read result registration unit 26 registers the tag data read in step S22, for example, in an inventory table F (see FIG. 2) (step S23).

[0058] The Q-value adjusting unit 23 determines whether there is a responding RFID tag TG (step S24). If it is determined that there is no responding RFID tag TG (step S24: Yes), the process proceeds to step S25. On the other hand, if it is not determined that there is no responding RFID tag TG (step S24: No), the process returns to step S21.

[0059] If it is determined in step S24 that there is no responding RFID tag TG, the reading control unit 27 stops the reading process by the first reading unit 21 (step S25), and then returns to the main routine of FIG. 5A.

[0060] (MS method reading flow) The flow of the reading process by the MS method performed by the second reading unit 22 will be described with reference to Fig. 5C. Fig. 5C is a flowchart showing an example of the flow of the reading process by the MS method.

[0061] The Q value adjustment unit 23 adjusts the Q value related to reading the RFID tag TG according to the response state of the RFID tag TG (step S31).

[0062] The second reading unit 22 reads the information held by the RFID tag TG by the MS method (step S32). When reading the information held by the RFID tag TG, the above-mentioned time slot method is used.

[0063] The read result registration unit 26 registers the tag data read in step S32, for example, in an inventory table F (see FIG. 2) (step S33).

[0064] The Q-value adjusting unit 23 determines whether there is a responding RFID tag TG (step S34). If it is determined that there is no responding RFID tag TG (step S34: Yes), the process proceeds to step S35. On the other hand, if it is not determined that there is no responding RFID tag TG (step S34: No), the process returns to step S31.

[0065] If it is determined in step S34 that there is no responding RFID tag TG, the reading control unit 27 stops the reading process by the second reading unit 22 (step S35), and then returns to the main routine of FIG. 5A.

[0066] In this embodiment, in the RFID tag reader 10, the first reader 21 reads information held by the RFID tag TG using the FM0 method, and the second reader 22 reads information held by the RFID tag TG using the MS method, but the reading method is not limited to this. For example, reading parameters of the same FM0 method, such as the reading frequency, may be changed. Also, reading parameters of the same MS method, such as the reading frequency and the data length used, may be changed.

[0067] As described above, the RFID tag reader 10 (wireless tag reader) of the first embodiment includes a first reading unit 21 (first reading means) that reads information held in an RFID tag TG (wireless tag) present inside the communication area of ​​the antenna 151, and a second reading unit 22 (second reading means) that reads information held in an RFID tag TG present inside the communication area of ​​the antenna 151 with higher reading accuracy than the first reading unit 21. ), a Q-value adjusting unit 23 (adjusting means) that adjusts the Q-value for reading the RFID tag TG according to the response status of the RFID tag TG when the first reading unit 21 or the second reading unit 22 is used with a setting that prevents an RFID tag TG that has been read once from responding for a predetermined period of time or more, and a reading method switching unit 24 (switching means) that switches between the first reading unit 21 and the second reading unit 22 to read the RFID tag TG according to the magnitude relationship between the Q-value and a switching threshold Th (threshold value). Therefore, when reading a large number of RFID tags TG, it is possible to achieve both high reading speed and high reading accuracy.

[0068] Furthermore, in the RFID tag reader 10, the first reading unit 21 (first reading means) is of the FM0 type. Therefore, when reading an RFID tag TG, it can read the tag at a higher speed than the second reading unit 22. For example, it is desirable to read an RFID tag TG that is close and easy to read using the FM0 type.

[0069] Furthermore, in the RFID tag reader 10, the second reading unit 22 (second reading means) is of the mirror sub-scan type. Therefore, when reading an RFID tag TG, it can be read with higher reading accuracy than the first reading unit 21. For example, it is desirable to read an RFID tag TG that is located in a difficult-to-read position and requires high reception sensitivity by the mirror sub-scan type.

[0070] The RFID tag reader 10 further includes a threshold setting unit 25 (setting means) that sets a switching threshold Th (threshold value). Therefore, the threshold value for switching between reading by the first reading unit 21 and reading by the second reading unit 22 can be freely set.

[0071] Furthermore, in the RFID tag reader 10, the reading method switching unit 24 (switching means) reads the RFID tag TG using the first reading unit 21 on the condition that the Q value is equal to or greater than the switching threshold Th, and reads the RFID tag TG using the second reading unit 22 on the condition that the Q value is smaller than the switching threshold Th. Therefore, it is possible to switch to an appropriate reading method depending on the response status of the RFID tag TG. This allows high-speed reading using the first reading unit 21 when there are many collisions, and high-accuracy reading using the second reading unit 22 when there are many no-response slots.

[0072] Although the embodiments of the present invention have been described above, these embodiments are merely examples and are not intended to limit the scope of the invention. This novel embodiment 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 inventions and their equivalents as defined in the claims. [Explanation of symbols]

[0073] 10 RFID tag reader (wireless tag reader) 21 First reading unit (first reading means) 22 Second reading unit (second reading means) 23 Q value adjustment unit (adjustment means) 24 Reading method switching unit (switching means) 25 Threshold setting unit (setting means) 26 Reading result registration section 27 Reading control unit 100 control section 151 Antenna G Goods R response wave S Transmitted wave TG RFID tag (wireless tag) Th Switching threshold (threshold) [Prior art documents] [Patent documents]

[0074] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-219458 [Patent Document 2] Japanese Patent Application Laid-Open No. 2010-21684

Claims

1. a first reading means for reading information stored in the wireless tag; a second reading means for reading information stored in the wireless tag with higher reading accuracy than the first reading means; an adjustment means for adjusting a Q value relating to reading of the wireless tag in accordance with the response status of the wireless tag when the first reading means or the second reading means is used under a setting that prevents a wireless tag that has been read once from responding for a predetermined period of time or longer; a switching means for causing the first reading means to read the wireless tag on condition that the Q value is equal to or greater than a threshold value, and causing the second reading means to read the wireless tag on condition that the Q value is less than the threshold value; A wireless tag reader comprising:

2. the first reading means is an FM0 system; 2. The wireless tag reader according to claim 1.

3. the second reading means is a mirror sub-scan type; 3. The wireless tag reader according to claim 1 or 2.

4. further comprising a setting means for setting the threshold value; 2. The wireless tag reader according to claim 1.

5. A computer that controls a wireless tag reader a first reading means for reading information stored in the wireless tag; a second reading means for reading information stored in the wireless tag with higher reading accuracy than the first reading means; an adjustment means for adjusting a Q value relating to reading of the wireless tag in accordance with the response status of the wireless tag when the first reading means or the second reading means is used under a setting that prevents a wireless tag that has been read once from responding for a predetermined period of time or longer; a switching means for causing the first reading means to read the wireless tag on condition that the Q value is equal to or greater than a threshold value, and causing the second reading means to read the wireless tag on condition that the Q value is less than the threshold value; A program that makes it work.

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