JP7269310B2 - Radio tag reader and program - Google Patents

Description

The embodiments of the present invention relate to a wireless tag reader and program.

2. Description of the Related Art Conventionally, there is known an inventory management system that manages inventory of commodities using wireless communication technology. Such an inventory management system uses a wireless tag reader that reads information from the wireless tags of products displayed on product shelves or the like by transmitting radio waves over a wide range.

By the way, in the inventory management system as described above, when there are a large number of wireless tags to read information from, it takes a considerable amount of time to read information from all the wireless tags. In addition, if the number of RFID tags is large, for example, when reading information from a fixed position, the number of RFID tags that are out of reach of radio waves from the RFID tag reader also increases, reducing work efficiency. I can.

The problem to be solved by the embodiments of the present invention is to provide a wireless tag reader and a program capable of realizing shortening and efficiency of reading information from a large number of wireless tags.

A wireless tag reader according to an embodiment acquires predetermined information from a plurality of wireless tags by performing wireless communication with the wireless tags. This wireless tag reader has a first acquisition section and a second acquisition section. The first obtaining unit obtains predetermined information from the first wireless tag by transmitting a predetermined request by wireless communication at a first transmission rate, and indicates the number of responses from the first wireless tag to the request . When the value becomes equal to or less than the first threshold value, acquisition of the predetermined information is terminated. After the acquisition of the predetermined information by the first acquisition unit is completed, the second acquisition unit transmits a request by wireless communication at a second transmission speed slower than the first transmission speed, thereby obtaining the first wireless tag and acquires predetermined information from a different second wireless tag, and when the number of responses from the second wireless tag to the request is equal to or less than the second threshold value, the acquisition of the predetermined information is terminated. The first retriever sets the first threshold as a percentage of the maximum number of responses the first retriever can accept to the request.

FIG. 1 is an exemplary diagram showing the configuration of an inventory management system using a wireless tag reader according to the first embodiment. FIG. 2 is an exemplary block diagram showing the hardware configuration of the wireless tag according to the first embodiment. FIG. 3 is an exemplary block diagram showing the hardware configuration of the wireless tag reader according to the first embodiment. FIG. 4 is an exemplary diagram for explaining characteristics of the first transmission rate and the second transmission rate used in the first embodiment. FIG. 5 is an exemplary block diagram showing functions implemented within the control unit of the wireless tag reader according to the first embodiment. FIG. 6 is an exemplary flowchart showing a series of processes executed in the first embodiment. FIG. 7 is an exemplary block diagram showing functions implemented within the control unit of the wireless tag reader according to the second embodiment. FIG. 8 is an exemplary flowchart showing a series of processes executed in the second embodiment.

Hereinafter, a wireless tag reader and a program according to embodiments will be described with reference to the accompanying drawings. An example in which the wireless tag reader according to the embodiment is configured as a portable RFID (Radio Frequency Identification) reader/writer used in a product inventory management system will be described below. RFID reader/writer.

<First embodiment>
First, the configuration of the first embodiment will be described.

FIG. 1 is an exemplary diagram showing the configuration of an inventory management system using a wireless tag reader 100 according to the first embodiment. As shown in FIG. 1, the inventory management system according to the first embodiment includes a wireless tag 20 and a wireless tag reader 100. FIG. The wireless tag 20 and the wireless tag reader 100 are configured to be able to perform wireless communication using electromagnetic waves or the like. In the following description, it is assumed that the wireless communication method executed between the wireless tag reader 100 and the wireless tag 20 is the time slot method.

The wireless tag 20 is an RFID tag called an electronic tag or an IC (Integrated Circuit) tag attached to a product 10 sold at a retail store or the like. The wireless tag 20 stores predetermined information (tag information 226 to be described later) including a product code for identifying the product 10 and the like. The wireless tag 20 reads/writes the tag information 226 stored therein based on a signal (radio wave signal) transmitted/received to/from the wireless tag reader 100 .

The wireless tag reader 100 reads the tag information 226 stored in the wireless tag 20 by wireless communication according to the operation of the operator. That is, by operating the wireless tag reader 100 toward the product shelf 10a on which the product 10 is displayed, the operator reads the tag from the wireless tag 20 attached to the product 10 to the wireless tag reader 100 by wireless communication. Cause information 226 to be sent.

More specifically, the wireless tag reader 100 transmits radio waves requesting transmission of the tag information 226 to the wireless tag 20 according to the operator's operation. In response to a request from the wireless tag reader 100, the wireless tag 20 sends back radio waves containing the tag information 226 stored therein. This reply is executed only by the wireless tag 20 existing within the radio wave range from the wireless tag reader 100 . The wireless tag reader 100 reads the tag information 226 stored in the wireless tag 20 by receiving radio waves including the tag information 226 transmitted from the wireless tag 20 .

Although not shown in FIG. 1, in the first embodiment, a server device that collects information read by the wireless tag reader 100 may be provided. A server device is, for example, a personal computer. Note that the server device may be provided by a cloud service or the like that provides computer resources such as hardware and software.

Next, the hardware configuration of various devices included in the inventory management system according to the first embodiment will be described.

FIG. 2 is an exemplary block diagram showing the hardware configuration of the wireless tag 20 according to the first embodiment. As shown in FIG. 2 , the wireless tag 20 has an antenna 210 and an IC chip 220 .

The antenna 210 is a device for transmitting and receiving radio waves to and from the wireless tag reader 100 . The IC chip 220 includes a power generation section 221 , a demodulation section 222 , a control section 223 , a modulation section 224 and a storage section 225 .

The power generation unit 221 supplies power to each unit of the IC chip 220 based on the radio waves received by the antenna 210 by the principle of electromagnetic induction or the like. The demodulator 222 demodulates the radio wave received by the antenna 210 and outputs the demodulated signal to the controller 223 .

The control unit 223 has a function of writing information demodulated by the demodulation unit 222 to the storage unit 225 and reading information from the storage unit 225 and outputting it to the modulation unit 224 . Modulation section 224 modulates the information output from control section 223 and outputs the modulated information to antenna 210 . The information output from the modulation section 224 is transmitted over radio waves via the antenna 210 .

Storage unit 225 is a non-volatile rewritable storage medium such as EEPROM (Electrically Erasable Programmable Read-Only Memory). The storage unit 225 is configured to be able to store information even when power is not supplied. The storage unit 225 stores tag information 226 .

Tag information 226 includes identification information and sales information. The identification information is information for identifying the product 10 (that is, the product code described above). The sales information is information indicating the sales status of the product 10 to which the wireless tag 20 is attached.

FIG. 3 is an exemplary block diagram showing the hardware configuration of the wireless tag reader 100 according to the first embodiment. As shown in FIG. 3, the wireless tag reader 100 includes a control section 101, a storage section 102, a communication interface 103, an operation section 104, an RFID reader 105, and an antenna 110. FIG. These units are interconnected via a system bus 106 .

The control unit 101 comprehensively controls the operation of the wireless tag reader 100 and implements various functions of the wireless tag reader 100 . The control unit 101 includes a processor, memory, and the like.

The storage unit 102 is a storage device such as flash memory. A control program 107 that is read and executed by the processor of the control unit 100 is stored in the storage unit 102 . Needless to say, information other than the control program 107 can also be stored in the storage unit 102 .

The communication interface 103 is an interface for communicating with the outside (for example, the server device described above).

The operation unit 104 is a device that receives operation input from the operator of the wireless tag reader 100 . The operation unit 104 includes hardware keys such as buttons and switches, a touch panel provided on the display, and the like.

The RFID reader 105 reads tag information 226 stored in the wireless tag 20 by controlling the antenna 110 which is a device for transmitting and receiving radio waves to and from the wireless tag 20 . More specifically, when the RFID reader 105 reads the tag information 226 of the wireless tag 20 , first, the antenna 110 transmits radio waves requesting the wireless tag 20 to transmit the tag information 226 . Then, the RFID reader 105 receives the radio waves returned from the wireless tag 20 in response to the request by the antenna 110 , demodulates the received radio waves, and extracts the tag information 226 .

By the way, in the inventory management system as described above, when there are many wireless tags 20 whose tag information 226 should be read, it takes a considerable amount of time to read the tag information 226 from all the wireless tags 20 . In addition, if the number of wireless tags 20 is large, for example, when the task of reading the tag information 226 is performed at a fixed position, the number of wireless tags 20 that are out of reach of requests from the wireless tag reader 100 also increases. efficiency can be reduced.

Therefore, the wireless tag reader 100 according to the first embodiment uses a plurality of transmission rates with different characteristics in stages when requesting the wireless tag 20 to transmit the tag information 226. It realizes shortening and efficiency of the work of reading the tag information 226 from the tag 20. - 特許庁

For example, the wireless tag reader 100 according to the first embodiment has a relatively high first transmission rate and a relatively low second transmission rate (that is, slower than the first transmission rate) as described below. A request to the wireless tag 20 is transmitted using two types of transmission speeds, namely, the transmission speed and the transmission speed, in stages.

FIG. 4 is an exemplary diagram for explaining characteristics of the first transmission rate and the second transmission rate used in the first embodiment. In FIG. 4, R1 represents the range within which the request for the first transmission speed reaches (communication range), and R2 represents the range within which the request for the second transmission speed reaches.

As shown in FIG. 4, when the communicable distances at the first transmission rate and the second transmission rate are compared, the communicable range R2 at the second transmission rate allows communication at the first transmission rate. It is larger than the range R1.

Here, the reason why the difference in the transmission speed causes the difference in the communicable range will be briefly described. Generally, in wireless communication, when the transmission speed of a radio wave signal is high, it is easily affected by noise. Also, when the output level of the radio signal becomes low, transmission errors are more likely to occur. Therefore, if the transmission output and the reception sensitivity are the same, the lower the transmission speed, the larger the reach of the radio signal (communication range).

As described above, the first transmission rate has the characteristic that although the communicable range is lower than the second transmission rate, the reading rate of the tag information 226 from the wireless tag 20 is higher than the second transmission rate. can be said to have Further, the second transmission speed has a characteristic that although the reading speed of the tag information 226 from the wireless tag 20 is lower than the first transmission speed, the communicable range is higher than the first transmission speed. can be said to have

Based on the above characteristics, the wireless tag reader 100 according to the first embodiment, when requesting the wireless tag 20 to transmit the tag information 226, first transmits the request at the first transmission rate. The tag information 226 is acquired from the wireless tag 20 at a relatively short distance, and then the tag information 226 is acquired from the remaining wireless tags 20 at a relatively long distance by transmitting a request at the second transmission rate. As a result, by using the first transmission speed, it is possible to shorten the work of reading the tag information 226, and by using the second transmission speed, it is possible to improve the efficiency of reading the tag information 226. It will be possible to achieve

In the first embodiment, the wireless tag 20 responding to the request at the first transmission rate does not respond to subsequent requests at the second transmission rate. That is, in the first embodiment, the wireless tag reader 100 executes the request at the first transmission rate and the subsequent request at the second transmission rate as a series of processes (rounds), A tag 20 is configured such that once it responds in a round, it will not respond again until the round is updated.

In the first embodiment, such proper use of the first transmission rate and the second transmission rate is realized by the following functions.

FIG. 5 is an exemplary block diagram showing functions realized within the control unit 101 of the wireless tag reader 100 according to the first embodiment. As shown in FIG. 5, within the control unit 101, a first acquisition unit 501, a second acquisition unit 502, and a reception unit 503 are implemented. These functions are realized on the memory of the control unit 101 as a result of the processor of the control unit 101 reading out and executing the control program 107 of the storage unit 102 .

In the first embodiment, the functions shown in FIG. 5 are not limited to being realized by cooperation between hardware (control unit 101) and software (control program 107). The functions provided may be realized only by dedicated hardware (circuits).

The first acquisition unit 501 transmits a request for transmission of the tag information 226 to the wireless tag 20 at the first transmission rate, so that the wireless tag 20 (hereinafter referred to as the first wireless tag) existing within the range of the request is transmitted. described) to obtain the tag information 226. Then, the first acquisition unit 501 ends the acquisition of the tag information 226 when the acquisition of the tag information 226 from substantially all of the first wireless tags is completed.

Here, in the first embodiment, as described above, the method of wireless communication executed between the wireless tag reader 100 and the wireless tag 20 is the time slot method. Therefore, there is a limit to the number of responses from the wireless tags 20 that can be accepted by the first acquisition unit 501 for one request.

Therefore, in the first embodiment, the first acquisition unit 501 repeatedly executes transmission of the request at the first transmission rate multiple times. Then, when the value indicating the number of responses from the first wireless tag to one request becomes equal to or less than a predetermined threshold (first threshold), the first acquisition unit 501 obtains the first It is determined that the acquisition of responses from almost all wireless tags has been completed, and the acquisition of tag information 226 from the first wireless tag ends.

Note that the first threshold may be set as a specific numerical value corresponding to the number of responses, or may be It may be set as a percentage.

After the acquisition of the tag information 226 by the first acquisition unit 501 is completed, the second acquisition unit 502 transmits a request for transmission of the tag information 226 to the wireless tag 20 at the second transmission rate. The tag information 226 is acquired from the wireless tag 20 different from the tag, more specifically, from the remaining wireless tag 20 (hereinafter referred to as the second wireless tag) whose tag information 226 was not acquired by the first acquisition unit 501. do. Then, the second acquisition unit 502 ends the acquisition of the tag information 226 when the acquisition of the tag information 226 from substantially all of the second wireless tags is completed.

Note that the criterion for determining whether or not the acquisition of the tag information 226 from substantially all of the second wireless tags has been completed is that the acquisition of the tag information 226 from substantially all of the first wireless tags has been completed. Since it can be set in substantially the same manner as the above-described criteria for determining whether or not, a description thereof will be omitted here.

By the way, if the operator can arbitrarily change the first threshold value that serves as a reference for switching from the first transmission rate to the second transmission rate, convenience will be further improved.

Therefore, in the first embodiment, a receiving unit 503 is provided as a function of receiving a change of the first threshold value by the operator.

Next, the control operation of the first embodiment will be explained.

FIG. 6 is an exemplary flowchart showing a series of processes executed in the first embodiment. The processing flow of FIG. 6 starts in response to the operation of the wireless tag reader 100 by the operator.

In the processing flow of FIG. 6, first, in S601, the first acquisition unit 501 transmits a request for transmission of the tag information 226 to the wireless tag 20 that has not yet acquired the tag information 226 at the first transmission rate.

Then, in S602, the first acquisition unit 501 determines whether or not substantially all of the information that can be obtained by the processing of S601 has been obtained, that is, substantially all of the first wireless tags within the reach of the request for the first transmission rate. It is determined whether or not acquisition of the tag information 226 from is completed. The above-described first threshold value is used for this determination.

If it is determined in S602 that acquisition of the tag information 226 from substantially all of the first wireless tags has not been completed yet, the process returns to S601. On the other hand, if it is determined in S602 that the acquisition of the tag information 226 from substantially all of the first wireless tags has been completed, the acquisition of the tag information 226 by the first acquisition unit 501 ends, and the process proceeds to S603.

In S603, the second acquisition unit 502 transmits a request for transmission of the tag information 226 to the wireless tag 20 that has not acquired the tag information 226 at the second transmission rate.

Then, in S604, the second acquisition unit 502 determines whether or not substantially all of the information that can be acquired by the processing in S603 has been acquired, that is, the remaining second wireless devices for which the tag information 226 has not been acquired by the first acquisition unit 501. It is determined whether or not the acquisition of tag information 226 from substantially all tags has been completed. This determination also uses a threshold value similar to the first threshold value described above.

If it is determined in S604 that acquisition of the tag information 226 from substantially all of the second wireless tags has not been completed yet, the process returns to S603. On the other hand, if it is determined in S604 that the acquisition of the tag information 226 from substantially all of the second wireless tags has been completed, the acquisition of the tag information 226 by the second acquisition unit 502 ends, and the processing flow of FIG. finish.

As described above, the wireless tag reader 100 according to the first embodiment acquires predetermined information (tag information 226) from the plurality of wireless tags 20 by performing wireless communication with the plurality of wireless tags 20. Configured. This wireless tag reader 100 transmits a predetermined request one or more times by wireless communication at a first transmission speed, thereby acquiring tag information 226 from a first wireless tag among a plurality of wireless tags 20. After the acquisition of the tag information 226 by the acquisition unit 501 and the first acquisition unit 501 is completed, a request is transmitted one or more times through wireless communication at a second transmission rate that is lower than the first transmission rate. and a second acquiring unit 502 for acquiring tag information 226 from a second wireless tag different from the first wireless tag among the wireless tags 20 . Here, the first wireless tag is the wireless tag 20 within the range where the request for the first transmission rate can be reached. It is the remaining wireless tag 20 .

According to the above configuration, by using the first transmission speed, it is possible to shorten the work of reading the tag information 226. Then, by further using the second transmission speed, it is possible to read the tag information 226. Reading efficiency can be improved. Therefore, according to the first embodiment, the work of reading the tag information 226 from many wireless tags 20 can be shortened and made more efficient.

<Second embodiment>
In addition, in the first embodiment, an example in which two types of transmission speeds, the first transmission speed and the second transmission speed, are used in stages has been described. However, as in the second embodiment described below, the technique of the embodiment can also be applied to an example in which two or more transmission rates are used in stages.

For example, in the first embodiment, when the number of responses to the first request at the second transmission rate is relatively large, the arrangement density of the wireless tags 20 is high and many wireless tags 20 have not acquired the tag information 226. presumed to remain. Therefore, in this case, after the acquisition of the tag information 226 at the second transmission speed is completed, at a new transmission speed with a larger communicable range than the second transmission speed (that is, slower than the second transmission speed). There is room for further acquisition of the tag information 226 of the .

Therefore, in the second embodiment, first, as in the first embodiment, the tag information 226 is acquired from the wireless tag 20 by using the first transmission rate and the second transmission rate in stages. Then, in the second embodiment, when the number of responses to the first request at the second transmission rate is large to some extent, wireless communication at a third transmission rate slower than the second transmission rate is further used. , the tag information 226 is acquired from the remaining wireless tags 20 whose tag information 226 was not acquired with the requests for the first transmission rate and the second transmission rate.

The functions of the second embodiment will be described in more detail below.

FIG. 7 is an exemplary block diagram showing functions realized within the control unit 101 of the wireless tag reader 100 according to the second embodiment. Each function shown in FIG. 7 is implemented by the control unit 101 executing a control program different from the control program 107 (see FIG. 3) according to the first embodiment.

As shown in FIG. 7, in the second embodiment, a first acquisition unit 701 similar to the first acquisition unit 501, the second acquisition unit 502, and the reception unit 503 in the first embodiment (see FIG. 5), In addition to the second acquisition unit 702 and reception unit 704, a third acquisition unit 703 is provided to acquire the tag information 226 at the third transmission rate described above.

If the arrangement density of the wireless tags 20 is high and it is estimated that many wireless tags 20 that have not yet acquired the tag information 226 remain, the third acquisition unit 703 After the processing of the stage ends, acquisition of the tag information 226 at the above-mentioned third transmission rate is started. Then, when the acquisition of the tag information 226 from substantially all of the remaining wireless tags 20 is completed, the third acquisition unit 703 ends the acquisition of the tag information 226 .

More specifically, when the value indicating the number of responses to the first request sent by the second obtaining unit 702 is equal to or greater than a predetermined threshold (second threshold), the third obtaining unit , after the acquisition of the tag information 226 by the second acquisition unit 702 is completed, the request is transmitted by wireless communication at a third transmission speed that is slower than the second transmission speed used by the second acquisition unit 702. , acquires the tag information 226 from the remaining wireless tags 20 (hereinafter referred to as third wireless tags) that could not be acquired by the first acquiring unit 701 and the second acquiring unit 702 . Then, the third acquisition unit 703 terminates acquisition of the tag information 226 when the number of responses from the third wireless tags to the request at the third transmission rate becomes small.

Other configurations of the second embodiment are the same as those of the first embodiment, so descriptions thereof are omitted.

Here, the control operation of the second embodiment will be described.

FIG. 8 is an exemplary flowchart showing a series of processes executed in the second embodiment. Note that the processing of S801 to S804 in the processing flow of FIG. 8 is the same as the processing of S601 to S604 in the processing flow of the first embodiment (see FIG. 6). only explained.

As shown in FIG. 8, in the second embodiment, when it is determined in S804 that substantially all of the information that the second acquisition unit 702 can acquire has been acquired, the process proceeds to S805.

Then, in S805, the third obtaining unit 703 determines whether further switching of the transmission speed is necessary, that is, whether it is necessary to obtain the tag information 226 at the third transmission speed slower than the second transmission speed. to judge. The determination in S805 is made when the number of responses to the first request sent by the second acquisition unit 702 at the second transmission rate is equal to or greater than the predetermined threshold (second threshold) for the first processing of S803. or not.

If it is determined in S805 that the number of responses to the first processing of S803 is less than the second threshold, it is determined that further switching of the transmission rate is unnecessary, and the processing ends. On the other hand, if it is determined in S805 that the number of responses to the first processing of S803 is equal to or greater than the second threshold, it is determined that further switching of the transmission rate is necessary, and the processing proceeds to S806.

In S806, the third acquisition unit 703 transmits a request for transmission of the tag information 226 to the wireless tag 20 that has not acquired the tag information 226 at the third transmission rate.

Then, in S807, the third acquisition unit 703 determines whether substantially all of the information that can be acquired by the processing in S806 has been acquired, that is, whether the tag information 226 has not been acquired by the first acquisition unit 701 and the second acquisition unit 702. It is determined whether or not acquisition of the tag information 226 from substantially all of the third wireless tags, which are the remaining wireless tags 20, has been completed.

If it is determined in S807 that acquisition of the tag information 226 from substantially all of the third wireless tags has not been completed yet, the process returns to S806. On the other hand, if it is determined in S807 that the acquisition of the tag information 226 from substantially all the third wireless tags has been completed, the acquisition of the tag information 226 by the third acquisition unit 703 ends, and the processing flow in FIG. finish.

As described above, in the second embodiment, in addition to the same configuration as in the first embodiment, a value indicating the number of responses from the second wireless tags to the first request transmitted by the second acquisition unit 702 is is equal to or greater than the second threshold value, after the acquisition of the tag information 226 by the second acquisition unit 702 is completed, the request is transmitted by wireless communication at a third transmission rate slower than the second transmission rate. A third acquisition unit 703 is provided for acquiring tag information 226 from a third wireless tag different from the first and second wireless tags among the plurality of wireless tags 20 . Thus, by using the third transmission rate in addition to the first transmission rate and the second transmission rate, the work of reading the tag information 226 from many wireless tags 20 can be made more efficient. can.

The program executed in the above-described first and second embodiments can be provided in a state pre-installed in a storage medium such as a ROM, but the mode of providing the program is not limited to this. . Programs to be executed in the first and second embodiments are stored as installable or executable files on CD-ROM, flexible disk (FD), CD-R, DVD (Digital Versatile Disk), etc. It may be provided in a state recorded on a computer-readable recording medium such as.

Also, the programs executed in the first and second embodiments may be provided or distributed by downloading them via a network from a computer connected to a network such as the Internet.

Although several embodiments of the present invention have been described above, the above-described embodiments are merely examples and are not intended to limit the scope of the invention. The novel embodiments described above can be embodied in various forms, and various omissions, replacements, and modifications can be made without departing from the scope of the invention. The above-described embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the scope of the invention described in the claims and equivalents thereof.

20 wireless tag 100 wireless tag reader 226 tag information (predetermined information)
501, 701 first acquisition unit 502, 702 second acquisition unit 503, 704 reception unit 703 third acquisition unit

Japanese Patent Publication No. 2007-504537

Claims (4)

A wireless tag reader that acquires predetermined information from the plurality of wireless tags by performing wireless communication with the plurality of wireless tags,
The predetermined information is acquired from the first wireless tag by transmitting a predetermined request by wireless communication at a first transmission rate, and the value indicating the number of responses from the first wireless tag to the request is the first. a first acquisition unit that terminates acquisition of the predetermined information when the value becomes equal to or less than one threshold;
By transmitting the request by wireless communication at a second transmission rate slower than the first transmission rate after the acquisition of the predetermined information by the first acquisition unit is completed, the first wireless tag a second method for acquiring the predetermined information from a different second wireless tag and terminating the acquisition of the predetermined information when the number of responses from the second wireless tag to the request is equal to or less than a second threshold value; an acquisition unit;
with
The first obtaining unit sets the first threshold as a ratio of the maximum number of responses that the first obtaining unit can accept to the request.
Radio tag reader. Further comprising a reception unit that receives a change of the first threshold,
The wireless tag reader according to claim 1 . After the acquisition of the predetermined information by the second acquisition unit is completed, by transmitting the request through the wireless communication at a third transmission rate slower than the second transmission rate, the first wireless tag and Further comprising a third acquisition unit that acquires the predetermined information from a third wireless tag different from the second wireless tag,
The wireless tag reader according to claim 1 or 2 . A computer of a wireless tag reader that acquires predetermined information from the plurality of wireless tags by executing wireless communication with the plurality of wireless tags,
The predetermined information is acquired from the first wireless tag by transmitting a request by the wireless communication at the first transmission rate, and the value indicating the number of responses from the first wireless tag to the request is the first number. a first acquisition step of terminating acquisition of the predetermined information when the value is equal to or less than a threshold value;
When the acquisition of the predetermined information by the first acquisition step is completed, the first wireless acquiring the predetermined information from a second wireless tag different from the tag, and terminating the acquisition of the predetermined information when the number of responses from the second wireless tag to the request is equal to or less than a second threshold value; a second obtaining step of
and
the first obtaining step sets the first threshold as a percentage of the maximum number of responses that the first obtaining step can accept for the request;
program.

Images