JP2010237927A - Rfid tag reading apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize a tag reader with a small number of collisions and short reading time regarding the tag readers reading information of a plurality of tags. <P>SOLUTION: When the number of tags R to be read is larger than a setting value Rth (S5: Yes), an output voltage V of transmission radio waves is set to the minimum output voltage V1 (S6), and an identification information request signal is transmitted to a tag 20 (S8). The output voltage is raised in a step-by-step manner, until a response is issued from any tag 20 (S20). When the number of tags R to be read is set to a value which is less than or equal to the setting value Rth (S5: No), the output voltage V of the transmission radio waves is set to a maximum voltage V8 (S7). <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an RFID tag reader that reads information stored in a plurality of RFID tags.

  Conventionally, the thing of patent document 1 is known as this kind of RFID tag reader. This uses a time slot Aloha method as an anti-collision method. Here, the time slot Aloha system will be described with reference to FIG. FIG. 7 is a sequence diagram showing processing for reading information recorded in an RFID tag (hereinafter abbreviated as a tag) using the slot aloha method.

  An RFID tag reader (hereinafter abbreviated as a tag reader) communicates with four tags A to D by radio waves. The number of time slots is assumed to be five. The tag reader transmits a request command for returning the identification information to each tag (time t1). Then, each tag that has received the request command returns its identification information to the tag reader in any time slot determined using a random number.

  In the example shown in FIG. 7, tags A and D return identification information to the tag reader in time slots ts0 and ts4, respectively. However, since the tags B and C select the same time slot ts1 and return the identification information, a collision (collision) has occurred. The tag reader determines that the response from the tag is abnormal based on the check code and received waveform of the signals returned from the tags B and C.

  Subsequently, when the tag reader transmits a selection command to the tag A that has returned identification information (t2), the tag A returns information stored in itself to the tag reader. Subsequently, when the tag reader transmits a selection command to the tag D (t3), the tag D returns information stored therein to the tag reader. Subsequently, the tag reader retransmits the request command to the tags B and C where the collision has occurred (t4).

  In this example, tags B and C return identification information to the tag reader in time slots ts2 and ts3, respectively. When the tag reader transmits a selection command to tag B (t5), tag B returns information to the tag reader. Subsequently, when the tag reader transmits a selection command to the tag C (t6), the tag C returns information to the tag reader. Subsequently, the tag reader transmits a request command to each tag again (t7), and after confirming that there is no response including a collision, the anti-collision process is terminated.

JP 2007-221348 A

  However, in the case of the anti-collision method, if the number of time slots is increased in order to reduce the collision of responses from tags, time slots (time) that are not used for communication are generated, so that information on all tags is read. The time required for this is increased. Conversely, if the number of time slots is reduced in order to shorten the time, collisions increase.

  Accordingly, the present invention has been made to solve the above-described problems, and an object of the present invention is to realize a tag reader that has few collisions and a short reading time in a tag reader that reads information from a plurality of tags.

  In order to achieve the above object, a first feature of the present invention is that transmission means for transmitting transmission radio waves to a plurality of RFID tags, reception means for receiving return radio waves from the plurality of RFID tags, and the reception means Reading means for reading information recorded in the RFID tag that has transmitted the reply radio wave based on the reply radio wave received by the RFID tag reader, wherein the transmission means outputs the output of the transmission radio wave. It is configured to be able to transmit to the plurality of RFID tags while gradually increasing from one output to a second output.

According to the first feature, the tag reader is configured to be able to transmit to a plurality of tags while gradually increasing the output of the transmission radio wave from the first output to the second output. Can be made to respond in order from the tag with the shortest distance to the tag reader.
Therefore, according to the first feature described above, it is possible to reduce collision of return radio waves compared to a tag reader that transmits a transmission radio wave with maximum output from the beginning and responds to all tags.
In addition, since the number of tags that respond first is small, the number of time slots can be reduced compared to the number of tags, so the time required to read all tag information can be shortened. .

  According to a second feature of the present invention, in the first feature described above, the first output is a minimum output capable of transmitting the transmission radio wave, and the second output is capable of transmitting the transmission radio wave. It is to be the maximum output.

  According to the second feature, the tag reader can transmit the transmission radio wave to the tag while gradually increasing the output of the transmission radio wave from the minimum output to the maximum output. Therefore, the tag reader can be used when the antenna performance of each tag is the same. It is possible to read information from a tag existing over a wide range from a tag present at the nearest position to a tag located at the farthest position.

  Furthermore, a third feature of the present invention is that, in the first or second feature described above, there is provided output changing means (S14) for changing at least one of the first and second outputs.

  According to the third feature, since the tag reader includes output changing means for changing at least one of the first and second outputs, the tag reader is present at the distance to the tag present at the nearest position and at the farthest position. Since an appropriate output range of the transmission signal can be set according to the distance to the tag to be performed, there is no possibility of generating a tag from which information cannot be read.

  Furthermore, a fourth feature of the present invention is that, in any one of the first to third features described above, the transmission means gradually increases the output of the transmission radio wave from the first output to the second output. In this case, there is a first response at the nth (n is a positive integer greater than or equal to 1) when the information is read once from all the tags to be read. The output is substantially the same as the output of the transmission radio wave transmitted to the tag, and is configured to be set as the first output at the (n + 1) th time.

According to the fourth feature described above, transmission of the transmission radio wave can be started at the (n + 1) th time with substantially the same output as the output of the transmission radio wave transmitted to the tag that responded first in the nth time.
Therefore, since it is not necessary to gradually increase the transmission radio wave from the minimum output, it is possible to shorten the time required to read all tag information.

  Further, according to a fifth feature of the present invention, in any one of the first to fourth features described above, the transmission means includes tag number input means for inputting the number of tags to be read. If the number of tags input by the tag number input means exceeds a preset value, the output of the transmission radio wave is gradually increased from the first output to the second output. However, when the number of tags is less than or equal to the set value, the output of the transmission radio wave is set to be larger than at least the first output and transmitted to the tag. is there.

When the number of tags from which information is read is larger than a preset value, there is a high probability that the return radio waves from the responding tag will collide.
Therefore, in such a case, as in the fifth feature described above, by transmitting the transmission radio wave to the tag while gradually increasing the transmission radio wave from the first output to the second output, the transmission radio wave can be transmitted once. Since the number of tags that respond to the response can be reduced, the probability that the return radio waves from the responding tags collide can be reduced.

Further, when the number of tags from which information is read is less than or equal to the set value, the probability that the responses from the tags collide is low.
Therefore, in such a case, as in the fifth feature described above, by transmitting the transmission radio wave to the tag at least larger than the first output, the transmission radio wave can be transmitted once. Since the number of responding tags can be increased, the time required to read all tag information can be shortened.

  Furthermore, a sixth feature of the present invention is that, in the fifth feature described above, the reading means counts the number of tags from which information has been read, and the counted number of tags is input by the tag number input means. The reading of the information is configured to end when the number of tags matches.

  According to the sixth feature, since the reading of information is terminated when the number of tags from which information is read matches the number of tags input by the tag number input means, There is no risk of reading information from many tags.

  Furthermore, a seventh feature of the present invention is that, in the fifth or sixth feature, a predetermined notification is made when the number of counted tags exceeds the number of tags input by the tag number input means. It is in providing a notification means for performing.

According to said 7th characteristic, it can alert | report that the number of the tags which read information exceeded the number of the tags input by the tag number input means.
Therefore, the operator of this tag reader can know that more tags have been read than the number scheduled to be read.

It is explanatory drawing which shows the main electrical structures of the tag reader which concerns on embodiment of this invention with a block. It is explanatory drawing which shows the structure of the control command table 2a. It is explanatory drawing of the control command storage area 5a. It is explanatory drawing which shows the main electrical structures of a tag with a block. 4 is a flowchart showing a flow of output voltage control executed by the main control unit 2. 6 is a flowchart showing a continuation of FIG. It is a sequence diagram which shows the process which reads the information currently recorded on the tag using a slot aloha system.

  An embodiment according to the present invention will be described with reference to the drawings. FIG. 1 is an explanatory diagram showing the main electrical configuration of the tag reader according to this embodiment in blocks. Note that the tag reader 1 and the tag 20 in this embodiment communicate according to the Gen2 (Global Class 1 Generation 2) communication standard of EPC (Electronic Product Code).

[Main electrical configuration of tag reader]
As shown in FIG. 1, the tag reader 1 includes a main control unit 2, a transmission circuit 3, a reception circuit 4, a memory 5, a transmission / reception antenna 6, an amplification circuit 7, a circulator 8, a power supply circuit 9, The battery 10 includes a display unit 11, a key operation unit 12, a filter circuit 13, and a control circuit 14.

  The key operation unit 12 includes a trigger switch that is operated when reading is started and a numeric keypad for inputting data such as the number of tags to be read. The display unit 11 is configured by a liquid crystal display device or the like, and displays the operation state of the tag reader 1 and information read from the tag 20, and also indicates that the number of read tags has exceeded a preset number. Display.

  The main control unit 2 includes a CPU, a ROM, a RAM, and the like, and controls the operation of the tag reader 1 according to an operation signal given from the key operation unit 12. Further, the main control unit 2 performs processing for outputting data to the transmission circuit 3, processing for data input from the reception circuit 4, processing for setting an initial value of the output voltage of the transmission radio wave, processing for updating the initial value, transmission Control for gradually increasing the output voltage of the radio wave, counting processing for the number of tags read information, processing for notifying that the number of tags counted by this counting processing is different from the number of tags input in advance are executed.

  Although the detailed configuration of the transmission circuit 3 is not shown, a conversion circuit that converts data output from the main control unit 2 into a modulation signal, and an ASK (Amplitude Shift Keying) modulation of the signal from the conversion circuit And a modulation circuit. The amplifier circuit 7 amplifies the signal from the modulation circuit with a predetermined amplification factor. The control circuit 14 outputs a control voltage for controlling the output voltage of the amplified signal output from the amplifier circuit 7 to the amplifier circuit 7. The control circuit 14 outputs a control voltage to the amplifier circuit 7 in accordance with a control command from the main control unit 2.

  A control command table 2 a shown in FIG. 2 is stored in the ROM of the main control unit 2. The control command table 2a is set so that control commands corresponding to the minimum control voltage to the maximum control voltage can be read. In this embodiment, the control command table 2a stores control commands D1 to D8 corresponding to eight control voltages from the minimum control voltage Vc1 to the maximum control voltage Vc8. The control voltages Vc1 to Vc8 correspond to the minimum output voltage V1 to the maximum output voltage V8 of the amplifier circuit 7.

The amplifier circuit 7 is configured to change the output voltage of the amplified signal in accordance with the control voltage from the control circuit 14, and the output power of the transmission radio wave is changed by the amplifier circuit 7 changing the output voltage of the amplified signal. It is like that.
The filter circuit 13 passes only a signal having a necessary frequency among the signals from the amplifier circuit 7.

  The circulator 8 prevents the high-frequency signal output from the filter circuit 13 from flowing in the reverse direction. That is, the high frequency signal input from the filter circuit 13 side is output to the transmission / reception antenna 6, and the high frequency signal input from the transmission / reception antenna 6 is output to the reception circuit 4 side. The transmitting / receiving antenna 6 transmits a high-frequency signal as a radio signal to the tag 20 and receives a radio signal from the tag 20.

Although the detailed configuration of the receiving circuit 4 is not shown, the demodulating circuit that demodulates the signal received by the transmitting / receiving antenna 6 and output from the circulator 8, and the binarization that binarizes the signal from the demodulating circuit A circuit and a restoration circuit for restoring a response signal from the tag 20 based on the digital data from the binarization circuit.
The power supply circuit 9 supplies operating power to the display unit 11 and each circuit based on the power supplied from the battery 10.

  The memory 5 includes a control command storage area 5a shown in FIG. 3, and the control command storage area 5a stores the control command selected by the main control unit 2 from the control command table 2a in an updatable manner. The memory 5 stores the number of tags input by the operator as the number of tags to be read and the number of tags actually read. In this embodiment, the memory 5 is a memory that can rewrite stored data, and is, for example, a flash memory such as an EEPROM, or a RAM.

[Main electrical configuration of tag]
FIG. 4 is an explanatory diagram showing the main electrical configuration of the tag in blocks. The tag 20 is a passive type tag and has an IC chip 21 mounted thereon. The IC chip 21 includes a transmission / reception antenna 22, a rectifier circuit 23, a demodulation circuit 24, a modulation circuit 25, a control circuit 26, and a memory 27.

  When the transmission radio wave transmitted from the tag reader 1 is input via the transmission / reception antenna 22, the rectification circuit 23 rectifies the carrier wave of the input transmission radio wave to generate an operation power source, and the control circuit 26 and other Supply to the component. The demodulation circuit 24 demodulates the reception data superimposed on the carrier wave and outputs it to the control circuit 26. The memory 27 stores rewritable information (hereinafter referred to as tag information) relating to an article or the like to which the tag 20 is attached, identification information for identifying the other tag, and the like.

  When the operation power is supplied from the rectifier circuit 23, the control circuit 26 reads information from the memory 27 and outputs it as transmission data to the modulation circuit 25. The modulation circuit 25 transmits the carrier wave from the memory 27. The response radio wave is generated by modulating the response radio wave, and the response radio wave is returned from the transmission / reception antenna 22 to the tag reader 1.

[Output voltage control]
Next, output voltage control executed by the main control unit 2 of the tag reader 1 to control the output voltage of the amplifier circuit 7 will be described. FIG. 5 is a flowchart showing a flow of the output voltage control, and FIG. 6 is a flowchart showing a continuation of FIG. The tag reader 1 uses a time slot Aloha method as an anti-collision method. Moreover, the antenna performance of each tag 20 shall be the same.

  When the power of the tag reader 1 is turned on, the main control unit 2 executes initial settings such as erasing data such as control commands stored in the memory 5 (steps in FIG. 5 (hereinafter, steps are abbreviated as S)). 1). Subsequently, when the operator of the tag reader 1 operates the key operation unit 12 and inputs the tag number R to be read, the main control unit 2 sets the input tag number R in the memory 5 (S2). .

  Subsequently, the main control unit 2 determines whether or not the trigger switch is turned on (S3). If it is determined that the trigger switch is turned on (S3: Yes), the main control unit 2 turns on the initial flag indicating that reading is the first time. (S4). Subsequently, the main control unit 2 determines whether or not the tag number R input in the previous S2 exceeds the set value Rth stored in the ROM as a tag reader-specific tag number in advance (S5). In this embodiment, the set value Rth is the number of time slots.

  If the main control unit 2 makes an affirmative determination (S5: Yes), it performs a process of setting the output voltage V of the transmission radio wave to the minimum output voltage V1 (S6). That is, the main control unit 2 reads the control command D1 with reference to the control command table 2a (FIG. 2), and stores the read control command D1 in the control command storage area 5a (FIG. 3). This is because when the tag number R to be read exceeds the set value Rth, if the output voltage of the transmission radio wave is increased from the first time, the probability that the response from the tag 20 will collide increases. This is because the transmission radio wave is transmitted and the number of responding tags is reduced.

  Subsequently, the main control unit 2 performs a process of transmitting an identification information request signal for requesting a return of identification information to the tag 20 (S8). That is, the main control unit 2 outputs data for creating the identification information request signal to the transmission circuit 3. The transmission circuit 3 modulates the carrier wave with the data input from the main control unit 2 and outputs the modulated signal to the amplification circuit 7. Further, the main control unit 2 reads the control command D1 stored in the control command storage area 5a in the previous S6, and outputs the read control command to the control circuit 14.

  As a result, the control circuit 14 outputs the control voltage Vc1 corresponding to the control command D1 to the amplifier circuit 7. Then, the amplifier circuit 7 amplifies the signal input from the transmission circuit 3 to the output voltage V1 corresponding to the control voltage Vc1, and outputs it to the filter circuit 13. The amplified signal that has passed through the filter circuit 13 is transmitted from the transmission / reception antenna 6 via the circulator 8 to the tag 20 as a transmission radio wave indicating an information request signal.

  Subsequently, the main control unit 2 determines whether or not there is a response from the tag 20 within a predetermined time after outputting the control command in the previous S8 (S9). That is, it is determined whether or not a reply radio wave on which the identification information is superimposed is received from the tag 20 that has received the transmission radio wave transmitted at the output voltage V1. Here, if the main control unit 2 determines that the reply radio wave is not received (S9: No), it determines whether or not the current output voltage V has reached the maximum output voltage V8 (S19), and the maximum output voltage. If it is determined that V8 has not been reached (S19: No), the current output voltage V is updated to an output voltage that is one step higher (S20).

  For example, if the current output voltage is the minimum output voltage V1, the minimum output voltage V1 is updated to an output voltage V2 that is one step higher than that. Then, the main control unit 2 transmits an identification information transmission request signal to the tag 20 with the output voltage updated in S20 (S8). If there is no response from any of the tags 20 (S9: No), the output voltage is increased again by one step (S19: No, S20).

  That is, the main control unit 2 increases the output voltage step by step from the minimum voltage V1 until there is a response from any tag 20. When there is a response from any tag 20 (S9: Yes), the reply radio wave received from the tag 20 is demodulated and the identification information is read (S10). Subsequently, the main control unit 2 performs a process of transmitting a tag information request signal for requesting a return of tag information to the tag 20 (S11).

  Specifically, the main control unit 2 outputs data for creating a tag information request signal to the transmission circuit 3. The transmission circuit 3 modulates the carrier wave with the data input from the main control unit 2 and outputs the modulated signal to the amplification circuit 7. Further, the main control unit 2 reads the control command corresponding to the output voltage one step higher than the output voltage corresponding to the control command stored in the control command storage area 5a in the previous S6 from the control command table 2a, and reads it out as the control command. Store in the storage area 5a. As a result, the control command stored in the previous control command storage area 5a is updated to a new control command.

For example, as shown in FIG. 3, the control command D1 stored in the control command storage area 5a is updated as a control command D2, D3... Each time a new output voltage is selected.
Then, the control command D1 stored in the control command storage area 5a is read, and the read control command is output to the control circuit 14.

  As a result, the control circuit 14 outputs the control voltage Vc1 corresponding to the control command D1 to the amplifier circuit 7. Then, the amplifier circuit 7 amplifies the signal input from the transmission circuit 3 to the output voltage V1 corresponding to the control voltage Vc1, and outputs it to the filter circuit 13. The amplified signal that has passed through the filter circuit 13 is transmitted from the transmission / reception antenna 6 via the circulator 8 to the tag 20 as a transmission radio wave indicating a tag information request signal.

Subsequently, the main control unit 2 receives the reply radio wave returned from the tag 20 that has received the tag information request signal transmitted in the previous S11 (S12), and displays the tag information superimposed on the received reply radio wave. Read (S13).
Subsequently, the main control unit 2 adds 1 to the reading count value Rc (S14 in FIG. 6). This read count value is a numerical value obtained by counting the number of tags that have actually read the tag information. Subsequently, the main control unit 2 determines whether or not the read number count value Rc has reached the tag number R to be read input in the previous S2 (S15).

  If the main control unit 2 determines that the read count value Rc has not reached the tag number R to be read (S15: No), the main control unit 2 determines whether the initial flag is ON (S16). If it is determined (S16: Yes), the output voltage of the current transmission radio wave is set to the initial voltage used first in the next reading (S17). For example, when the output voltage of the current transmission radio wave, that is, when an identification information request signal is transmitted to the tag 20 when a response is first received from any one of the tags 20, the output voltage of the transmission radio wave is V3. The output voltage V3 is set to the initial voltage used first in the next reading.

That is, in the next reading, among the tags to be read, the tag 20 that is closest to the tag reader 1 has a high probability of being present at the same distance as the previous time, so there was a first response in the previous reading. The output voltage of the transmission radio wave transmitted to the tag 20 is set to the output voltage used first in the next reading.
As a result, it is possible to omit the process of increasing the output voltage step by step from the minimum output voltage until there is a response from any one of the tags 20, so that the reading time can be shortened accordingly.

  Subsequently, the main control unit 2 turns off the initial flag because the first reading is completed (S18). Subsequently, the main control unit 2 transmits the identification information request signal again (S8 in FIG. 5), and executes a process of increasing the output voltage step by step until there is a response from any tag 20, and the result Then, the process of reading the identification information and the tag information from the tag 20 that has responded is executed.

  When the main control unit 2 determines that the read count value Rc has reached the tag number R to be read (S15: Yes in FIG. 6), the main control unit 2 ends the current read process, and the tag number R to be read next time is determined. Wait for input.

  As described above, when the tag number R to be read exceeds the set value Rth, that is, the number of time slots, the transmission radio wave is first transmitted with the minimum output voltage V1 until a response is received from any tag 20 Since the output voltage is increased step by step, the probability that a collision will occur can be reduced by the response of many tags 20 at a time.

  If the main control unit 2 determines that the tag number R to be read does not exceed the set value Rth, that is, is equal to or less than the set value Rth (S5: No in FIG. 5), the tag number R to be read is the time Since the number of slots is less than or equal to the probability of a response from the tag 20 colliding, the output voltage of the transmission radio wave is set to the maximum output voltage V8 (S7).

  Thus, when the number of tags R to be read is equal to or less than the number of time slots, the time required to read tag information from all tags can be shortened by transmitting the transmission radio wave at the maximum output voltage. .

  When the main control unit 2 determines that the output voltage V of the transmission radio wave has reached the maximum output voltage V8 (S19: Yes), the result of subtracting the tag number R to be read from the read number count value Rc is It is determined whether or not it is positive, that is, whether the number Rc of actually read tags is greater than or coincides with the number R of scheduled tags (S21).

  Here, if the main control unit 2 makes a positive determination that the number of tags actually read is larger than the planned number of tags (S21:> 0), it notifies the reading abnormality (S22). For example, by displaying a message notifying the abnormality on the screen of the display unit 11 (FIG. 1) or by turning on or blinking an abnormality notification LED arranged at a predetermined position of the tag reader 1, the abnormality of reading is indicated to the operator. Inform. On the other hand, if the main control unit 2 determines that the actually read tag number Rc matches the planned tag number R (S21: = 0), the main routine ends. Thereby, there is no possibility of reading information from tags larger than the planned number of tags.

[Other Embodiments]
(1) An output changing circuit that changes at least one of the minimum output voltage and the maximum output voltage of the transmission radio wave can be provided. For example, the control command table 2a (FIG. 2) is stored in a data rewritable storage medium such as a flash ROM, and a data rewrite instruction is issued from a computer connected to the tag reader 1 so as to be able to communicate with the control command table 2a. At least one of the set minimum voltage V1 and maximum voltage V8 is rewritten. Further, the above-described rewriting can be performed by operating the key operation unit 12 of the tag reader 1.

As described above, by providing the output change circuit described above, even if the specification such as the reception sensitivity or transmission output of the tag 20 changes, it is possible to cope with the change in the specification.
The output changing circuit corresponds to the output changing means described in claim 3.

(2) In the above-described embodiment, when the tag number R to be read is equal to or less than the set value Rth, the output voltage of the transmission radio wave is set to the maximum voltage. However, it can be set to a voltage higher than at least the minimum voltage. In this case, if the output voltage is insufficient and there is no response from any of the tags 20, the output voltage can be increased step by step in S20 until there is a response, so the output voltage is set to the maximum voltage. There is no risk of reading omission due to the absence.

(3) In the above-described embodiment, the case where the time slot Aloha method is used as the anti-collision method has been described. However, a method such as a slot marker method, a bit collision method, and a binary tree method can also be used.

1. Tag reader (RFID tag reader) 2. Main controller
2a ... Control command table, 5 ... Memory, 14 ... Control circuit,
20 .. Tag (RFID tag).

Claims (7)

A transmission means for transmitting transmission radio waves to a plurality of RFID tags;
Receiving means for receiving return radio waves from the plurality of RFID tags;
An RFID tag reader comprising: a reading unit that reads information recorded on an RFID tag that has transmitted the return radio wave based on the return radio wave received by the receiving unit;
The transmission means includes
An RFID tag reader configured to transmit to the plurality of RFID tags while gradually increasing the output of the transmission radio wave from the first output to the second output.   The RFID tag according to claim 1, wherein the first output is a minimum output capable of transmitting the transmission radio wave, and the second output is a maximum output capable of transmitting the transmission radio wave. Reader.   3. The RFID tag reader according to claim 1, further comprising output changing means for changing at least one of the first and second outputs. The transmission means includes
When transmitting from the first output to the RFID tag while gradually increasing the output of the transmission radio wave from the first output to reading the information from all the RFID tags to be read of information once In addition, the output substantially the same as the output of the transmission radio wave transmitted to the RFID tag that responded first in the nth (n is a positive integer of 1 or more) times is set as the first output in the (n + 1) th time. The RFID tag reader according to any one of claims 1 to 3, wherein the RFID tag reader is configured as follows. It has tag number input means for inputting the number of RFID tags to be read,
The transmission means includes
When the number of the RFID tags input by the tag number input means exceeds a preset set value, the output of the transmission radio wave is gradually increased from the first output to the second output. However, when the number of RFID tags is equal to or less than the set value, the output of the transmission radio wave is set to be larger than at least the first output and transmitted to the RFID tag. The RFID tag reader according to any one of claims 1 to 4, wherein the RFID tag reader is provided. The reading means includes
It is configured to count the number of RFID tags that have read information, and to finish reading the information when the counted number of RFID tags matches the number of RFID tags input by the tag number input means. The RFID tag reader according to claim 5, wherein   The information processing apparatus according to claim 5, further comprising a notification unit configured to perform a predetermined notification when the counted number of RFID tags exceeds the number of RFID tags input by the tag number input unit. RFID tag reader.

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