JP5338725B2 - Wireless tag reader - Google Patents

Description

  The present invention relates to a wireless tag reader.

  At present, various wireless tag systems for reading wireless tags with wireless tag readers are provided, and the applications of wireless tag readers are widespread. These wireless tag readers are becoming more sophisticated due to demands for increased use and improved convenience. For example, the wireless tag reader adjusts the output level of radio waves according to the environment, or transmits radio waves at a higher level. Something that enables a wider range of reading is provided. For example, Patent Literatures 1 and 2 are provided as such techniques.

JP 2006-233831 A JP 2006-259123 A

  By the way, in the wireless tag reader, when it is intended to increase the output as described above, for example, it is necessary to mount an amplifying means such as a power amplifier. As a countermeasure against such a problem, for example, a method of improving the efficiency of the power amplifier by using a distortion compensation technique or the like is conceivable, but this method has a large circuit scale and is difficult in terms of mountability and cost. In particular, such a difficulty becomes more conspicuous when configured as a portable terminal equipped with a battery. Further, when configuring as a portable terminal equipped with a battery, suppression of power consumption is an extremely important issue in order to ensure a longer operating time and suppress internal heat generation due to power loss.

  The present invention has been made to solve the above-described problems, and provides a configuration that can effectively improve power utilization efficiency in a wireless tag reader that can efficiently read a plurality of wireless tags using a collision prevention technology. The purpose is to do.

  The invention of claim 1 includes an antenna for transmitting and receiving electromagnetic waves, wireless communication means for performing wireless communication with a wireless tag through the electromagnetic waves transmitted and received from the antenna, slot number setting means for setting the number of slots, and the slots The number of slots set by the number setting means is prepared, and each wireless tag existing within the readable range of the wireless communication means is assigned to each slot, and each wireless tag is associated with unique identification information. Collision prevention means for performing prevention processing, wherein the wireless communication means recognizes each wireless tag based on identification information associated with each wireless tag by the collision prevention means, and each wireless tag. A wireless tag reader that communicates with the wireless tag reader to determine whether reading of the wireless tag within the readable range is complete And an output setting means configured to switch the transmission output of the electromagnetic wave from the antenna to a plurality of stages, and to increase the transmission output to a new stage after the determination of the reading completion by the reading completion determination means, Based on the transmission output set by the output setting means and the number of already read tags within the readable range until the reading completion determination means determines that the reading is completed, the transmission output is determined by the output setting means. Prediction means for predicting the number of unread tags that fall within the readable range when increased to the new stage, and the slot number setting means is based on the number of unread tags predicted by the prediction means Thus, the number of slots at the new stage is determined.

  According to a second aspect of the present invention, in the wireless tag reader according to the first aspect, the slot number setting means associates and defines the number of unread tag tags and the number of slots, and a storage unit that stores the table. , And the number of slots at the new stage is determined based on the number of unread tags predicted by the prediction means and the table stored in the storage unit.

  According to a third aspect of the present invention, in the wireless tag reader according to the first aspect, the slot number setting means is in the new stage according to a predetermined arithmetic expression using the number of unread tags predicted by the prediction means as a parameter. The number of slots is determined.

  According to a fourth aspect of the present invention, in the wireless tag reader according to any one of the first to third aspects, the output setting means outputs the transmission output at the start of reading by the wireless communication means in the plurality of stages. The minimum output is set, and the transmission output is increased step by step until the wireless tag is detected by the wireless communication means.

  According to a fifth aspect of the present invention, in the wireless tag reader according to the fourth aspect, the slot number setting means sets the slot number to a predetermined minimum number of slots when reading by the wireless communication means is started.

  According to a sixth aspect of the present invention, in the wireless tag reader according to any one of the first to fifth aspects, when the switching of the plurality of stages by the output setting unit is completed, the display by the display unit and the audio unit A completion notifying means for executing at least one of sound generation and generation of vibration by a vibration generator is provided.

  According to a seventh aspect of the present invention, in the wireless tag reader according to any one of the first to fifth aspects, when the switching of the plurality of stages by the output setting unit is completed and a new wireless tag is not detected. And non-detection notification means for executing at least one of display on the display unit, sound generation by the sound means, and generation of vibration by the vibration generator.

  According to an eighth aspect of the present invention, in the wireless tag reader according to any one of the first to seventh aspects, the wireless communication unit includes a power amplifier that amplifies a transmission signal for the antenna, and the output setting unit includes: The amplification value of the power amplifier is controlled.

  A ninth aspect of the present invention is the wireless tag reader according to any one of the first to seventh aspects, wherein the wireless communication means modulates an oscillator that generates a carrier wave and the carrier wave generated by the oscillator. And the output setting means changes the output level of the modulation signal from the modulator.

  According to a tenth aspect of the present invention, in the wireless tag reader according to any one of the first to seventh aspects, the wireless communication means includes a power amplifier that amplifies a transmission signal for the antenna, and the output setting means And a variable attenuator capable of adjusting an input voltage to the power amplifier.

According to the first aspect of the present invention, in a wireless tag reader that recognizes each wireless tag based on each identification information associated with each wireless tag by the collision preventing means and communicates with each wireless tag, the readable range of the wireless communication means The reading completion determination means for determining whether or not the reading of the wireless tag inside is completed, and the transmission output of the electromagnetic wave from the antenna can be switched in a plurality of stages, and transmitted after the reading completion determination by the reading completion determination means Based on the output setting means for increasing the output to a new stage, the transmission output set by the output setting means, and the number of read tags within the readable range until the reading completion determination means determines that reading is complete, Prediction means for predicting the number of unread tags that fall within the readable range when the transmission output is increased to a new stage by the output setting means is provided. Then, the slot number setting means determines the number of slots at a new stage based on the number of unread tags predicted by the prediction means.
In this way, the output of the electromagnetic wave from the antenna can be increased stepwise in response to the completion of the reading of the wireless tag, so that the output relative to the arrangement state of the wireless tag is compared with a configuration that always reads with a large output. Is less likely to be excessive, and power consumption can be effectively reduced. Further, when the output is increased to a new stage, the number of slots is determined after predicting a new number of unread tags, so that it is possible to read with a more appropriate number of slots in the new stage.

  In the invention of claim 2, the slot number setting means comprises a table in which the number of tags of the unread tag and the number of slots are defined in association with each other, and a storage unit for storing the table, and the unread read predicted by the prediction means. The number of slots at a new stage is determined based on the number of tags and a table stored in the storage unit. In this way, the relationship between the number of unread tags and the appropriate number of slots corresponding thereto is prepared as a table based on past experimental data, theoretical values, etc., so that appropriate slots can be used without complicated processing. The number can be determined quickly.

  In the invention of claim 3, the slot number setting means determines the slot number at a new stage by a predetermined arithmetic expression using the number of unread tags predicted by the prediction means as a parameter. In this way, an appropriate number of slots can be quickly determined without using complicated processing.

  In the invention of claim 4, the output setting means sets the transmission output to the minimum output of the plurality of stages at the start of reading by the wireless communication means, and the transmission output is stepwise until the wireless tag is detected by the wireless communication means. It is increasing gradually. In this way, since reading is performed step by step from a lower output, it is possible to effectively save power compared to a configuration in which a high output state continues for a long time from the start of reading.

  According to the invention of claim 5, the slot number setting means sets the slot number to a predetermined minimum slot number when reading by the wireless communication means is started. Since the output is set to a lower value at the start of reading, the number of unread tags tends to be lower, and if the number of slots is set to a predetermined minimum number of slots, the value is relatively suitable for the number of unread tags.

  According to the sixth aspect of the present invention, a completion notification unit is provided for executing at least one of display on the display unit, sound generation by the voice unit, and generation of vibration by the vibration generator when the switching of the plurality of stages by the output setting unit is completed. It has been. In this way, the gradual switching of the output is completed and the user can be informed that the output will not increase any more. Therefore, the user can quickly grasp when the increase in the output is completed and take appropriate action. It becomes easy to take.

  According to the seventh aspect of the present invention, when a plurality of stages of switching by the output setting means is completed and no new wireless tag is detected, at least one of display on the display unit, sound generation by the sound means, and generation of vibration by the vibration generator Non-detection notification means for executing is provided. In this way, the stepwise switching of the output is completed, and the user can be notified that the reading is completed within the maximum reading range. Therefore, the user can quickly grasp that the reading has been completed within the maximum reading range and easily take an appropriate action.

  According to an eighth aspect of the present invention, the wireless communication means includes a power amplifier that amplifies a transmission signal for the antenna, and the output setting means controls the amplification value of the power amplifier. In this way, a configuration that can switch the output from the antenna stepwise can be suitably realized.

  According to a ninth aspect of the present invention, the wireless communication means includes an oscillator that generates a carrier wave and a modulator that modulates the carrier wave generated by the oscillator, and the output setting means outputs the modulation signal from the modulator. The level is changing. In this way, a configuration that can switch the output from the antenna stepwise can be suitably realized.

  According to a tenth aspect of the present invention, in the wireless tag reader according to any one of the first to seventh aspects, the wireless communication unit includes a power amplifier that amplifies a transmission signal to the antenna, and the output setting unit includes the power amplifier. It is comprised by the variable attenuator which can adjust the input voltage with respect to. In this way, a configuration that can switch the output from the antenna stepwise can be suitably realized.

FIG. 1 is a block diagram schematically illustrating an electrical configuration of the wireless tag reader according to the first embodiment of the present invention. FIG. 2 is a block diagram illustrating an electrical configuration of a wireless tag read by the wireless tag reader of FIG. FIG. 3 is an explanatory diagram for explaining how the wireless tag is read by the wireless tag reader of FIG. FIG. 4 is a flowchart illustrating the flow of tag reading processing by the wireless tag reader of FIG. FIG. 5 is an explanatory diagram for explaining the anti-collision process. FIG. 6A is an explanatory diagram conceptually showing table data in which each output level that can be set in stages and the area of the reading range corresponding to each output level are associated with each other. These are explanatory drawings explaining a method for calculating the density based on the output level and the number of acquired tags, and a method for calculating the predicted number of tags based on the density. FIG. 6C is an explanatory diagram conceptually illustrating table data in which the number of predicted tags is associated with an optimum Q value.

[First embodiment]
Hereinafter, a first embodiment in which a wireless tag reader of the present invention is embodied will be described with reference to the drawings.
(Overall configuration of wireless tag reader)
First, the overall configuration of the wireless tag reader 1 according to the first embodiment will be outlined with reference to FIG. 1, and the configuration of the wireless tag will be described. FIG. 1 is a block diagram schematically illustrating an electrical configuration of the wireless tag reader according to the first embodiment of the present invention. FIG. 2 is a block diagram illustrating an electrical configuration of a wireless tag read by the wireless tag reader of FIG.

  As shown in FIG. 1, the wireless tag reader 1 is configured, for example, as a known RFID reader / writer in hardware, and reads data recorded in the wireless tag 50 described later or writes data to the wireless tag 50. It is configured to do. The wireless tag reader 1 is mainly configured by a control unit 10, a transmission circuit 20, a reception circuit 30, an antenna 40, a circulator 41, and the like.

  The control unit 10 is responsible for overall control of the wireless tag reader 1 and is configured by a CPU, FPGA, or the like. The control unit 10 is also provided with a transmission data generation unit 11 that provides transmission data to the transmission circuit 20, a decoding processing unit 12 that acquires and decodes binarized data from the reception circuit 30, and the like.

  The transmission circuit 20 includes a frequency synthesizer 21, a D / A converter 22, a baseband filter 23, a modulator 24, an RF band filter 25, a power amplifier 26, and the like.

  The frequency synthesizer 21 is configured to output a carrier having a predetermined frequency (carrier wave). The D / A converter 22 generates a baseband signal by converting transmission data (digital signal) generated by the transmission data generation unit 11 of the control unit 10 into an analog signal. The baseband filter 23 is configured as a band limiting filter (analog filter) for limiting to a predetermined baseband band, and out of the predetermined baseband band among the signals output from the D / A converter 22 The signal part is limited.

  The modulator 24 modulates the baseband signal output from the baseband filter 23 with the oscillation signal from the frequency synthesizer 21 and converts it into a modulated signal (RF signal). The RF band filter 25 is configured as a band limiting filter that limits the band of the signal output from the modulator 24 to a predetermined RF band, and the signal output from the modulator 24 is out of the predetermined RF band. The signal part is limited.

  The power amplifier 26 amplifies the input signal (the modulated signal modulated by the modulator 24 and output from the RF band filter 25) with a predetermined gain. An RF band signal output from the power amplifier 26 is output as a transmission radio wave via the circulator 41 and the antenna 40.

  On the other hand, the receiving circuit 30 includes an RF band filter 31, a demodulator 33, baseband band filters 34a and 34b, A / D converters 35a and 35b, and the like.

  The RF band filter 31 is configured as a band limiting filter for limiting to a predetermined RF band, and limits a signal portion outside the predetermined RF band in the received signal input via the antenna 40 and the circulator 41. ing. Further, the demodulator 33 is configured as a quadrature demodulator, for example, and outputs an in-phase component and a quadrature component based on an unmodulated carrier wave (reference signal) distributed from the frequency synthesizer 21 to the signal output from the RF band filter 31. It is extracted and converted into amplitude information and phase information.

  Each of the baseband filters 34a and 34b is configured as a band limiting filter that limits the band of a predetermined baseband signal, and for each of the in-phase component signal and the quadrature component signal converted by the demodulator 33. Thus, the signal portion outside the predetermined baseband is limited. The outputs from the baseband filters 34a and 34b are converted into digital signals by the A / D converters 35a and 35b, respectively, and input to the decoding processing unit 12.

  The control unit 10 is also connected to a display unit 14 (see FIG. 3) including an input key and a liquid crystal display (not shown). Further, a memory 13 made of a semiconductor memory such as a ROM, a RAM, a nonvolatile memory, or the like is connected to the control unit 10 so that various information can be stored.

The wireless tag 50 read by the wireless tag reader 1 is configured as shown in FIG. 2, for example.
The wireless tag 50 is configured as a known RFID tag in hardware, for example, and includes an antenna 51, a power supply circuit 52, a demodulation circuit 53, a control circuit 54, a memory 55, a modulation circuit 56, and the like as shown in FIG. It is configured. The power supply circuit 52 rectifies and smoothes the transmission signal (carrier signal) received from the wireless tag reader 1 via the antenna 51 to generate an operation power supply. The operation power supply includes the control circuit 54 and the like. Is supplied to each component.

  The demodulating circuit 53 demodulates the data superimposed on the transmission signal (carrier signal) and outputs it to the control circuit 54. The memory 55 includes various semiconductor memories such as a ROM and an EEPROM, and includes tag identification information (tag ID) for identifying the control program, the wireless tag 50, and data set by the user according to the use of the wireless tag 50. (Product data, logistics data, etc.) are stored. The control circuit 54 is configured to read the information and data from the memory 55 and output it as transmission data to the modulation circuit 56. The modulation circuit 56 performs load modulation on the carrier signal with the transmission data and performs the antenna 51. Is transmitted as a reflected wave.

(Reading process with wireless tag reader)
Next, tag reading processing performed by the wireless tag reader 1 according to the first embodiment will be described.
FIG. 3 is an explanatory diagram for explaining how the wireless tag is read by the wireless tag reader of FIG. FIG. 4 is a flowchart illustrating the flow of tag reading processing by the wireless tag reader of FIG. FIG. 5 is an explanatory diagram for explaining the anti-collision process.

  In the wireless tag reader 1 according to the present embodiment, for example, when an operation for reading the wireless tag 50 is performed by the user as illustrated in FIG. 3, processing for reading the wireless tag 50 is performed. This tag reading process is performed in a flow as shown in FIG. 4 when a predetermined operation is performed on an input key (not shown) connected to the control unit 10, for example, and first, the wireless tag 50 in the reading range is searched. Processing is executed (S1).

  The process of S1 is a process of determining whether or not a response from any one of the wireless tags 50 has been confirmed. If there is no response from any of the wireless tags 50, No in S2 and any one of the wireless tags If there is a response from the tag 50, it is determined Yes in S2.

  Here, the output setting performed in the present embodiment will be described. In the present embodiment, the output level at the time of reading in S1 and S4 can be switched to multiple levels (for example, 5 levels). Specifically, the amplification value of the power amplifier 26 can be controlled in multiple stages under the control of the control unit 10, thereby switching the electromagnetic wave transmission output from the antenna 40 to multiple stages. Further, the transmission output from the antenna 40 is set to the minimum output (for example, P1 in the example of FIG. 6A) among the plurality of switchable stages at the start of reading in FIG. 4 (that is, in the initial setting). Thereafter, each time the processing of S7 or S9 described later is performed, the set value is increased by one step, and the transmission output is increased by one step.

  Assuming such a configuration, if the answer is No in S2, it is determined whether or not the set output has been reached (S8). The “set output” is a predetermined maximum output, and the wireless tag reader 1 according to the present embodiment switches the output of the transmission radio wave in multiple stages within a range equal to or less than the set output (maximum output).

  If it is determined in S8 that the set output (maximum output) has been reached, the result in S8 is Yes, and the processing after S10 is performed. On the other hand, if it is not determined in S8 that the set output (maximum output) has been reached, No in S8. In this case, the transmission output is set to a level increased by one step (S9). The process of S1 is performed again with the increased transmission output. As described above, in this embodiment, the processes of S1, S2, S8, and S9 are repeated until the response from the wireless tag 50 is confirmed, and the transmission output is stepped until the response from the wireless tag 50 is confirmed. Will be gradually raised.

  In the present embodiment, the control unit 10 that controls the power amplifier 26 corresponds to an example of an “output setting unit”. When the reading by the wireless communication unit is started, the transmission output is set to the minimum output of a plurality of stages, It functions to increase the transmission output step by step until the wireless tag is detected by the communication means. Further, the transmission output is stepwise until the set output (predetermined maximum output) is reached. It functions to increase sequentially. In addition, it functions to increase the transmission output to a new stage after the completion of reading by the reading completion determining means described later (that is, every time reading processing in S4 described later is completed (when No is determined in S3)). .

  On the other hand, when it is determined that there is a response in S2 (when it is determined that the wireless tag 50 has been searched in S1), the result in S2 is Yes, and S3 and S4 are repeated until all the wireless tags 50 within the reading range are read. Will be. In this S3, it is determined whether or not there is an unacquired wireless tag 50 among the wireless tags 50 in the reading range (whether or not there is a wireless tag 50 that has not been completely read). If the wireless tag 50 is present, reading processing for the wireless tag 50 that has not been acquired is performed (S4).

  In this reading process, first, the anti-collision process is performed based on each setting value (initial value of Q value, initial value of output level, etc.) set in the memory 13 or the like, whereby each wireless tag 50 within the reading range. Is obtained.

As the anti-collision method, for example, a known method such as a slotted aloha method is adopted. In this slotted aloha system, the wireless tag reader 1 is provided with a number of time slots (number of slots) corresponding to a preset Q value, and a slot number is assigned to each time slot. In this embodiment, 2 to the power of Q (that is, 2 ^Q ) is the number of slots, and FIG. 5 conceptually illustrates the case where Q = 4, that is, the number of slots is 16, as an example. doing.

  When performing the anti-collision process, the wireless tag reader 1 first transmits a request command to the wireless tag in the readable range. On the other hand, upon receiving a request command transmitted from the wireless tag reader 1, each wireless tag existing within the readable range generates a random number within the range of the number of slots set by the wireless tag reader 1, and obtains a numerical value at random. ing. Then, as in the example of FIG. 5, the wireless tag reader 1 advances the set number of timeslots (16 in FIG. 5) in order, and each wireless tag has its own time slot. Returns a response together with its own unique identification information in the time slot of the selected numerical value. For example, in the example of FIG. 5, the wireless tag A acquires the numerical value “1” and responds at time slot 1 (TS1), and similarly, the wireless tag B acquires the numerical value “5”. , Responding at time slot 5 (TS5). The wireless tag reader 1 attaches the wireless tag that responds to the wireless tag to a time slot that has a response from one of the wireless tags and has no response from other tags, such as the time slots 1 and 5. Managed with unique identification information. The unique identification information is returned to the wireless tag reader 1 together with the response to the time slot from the wireless tag, for example, and the wireless tag managed by the unique identification information is already selected (recognized) wireless. Treated as a tag.

  On the other hand, if there is a response from a plurality of wireless tags in any time slot, the wireless tag is suspended without selecting any wireless tag in that time slot and proceeds to the next time slot. In the example of FIG. 5, since the wireless tags D and F respond in the time slot 3 (TS3) and cannot be distinguished due to collision of the wireless tags, no wireless tag is selected in the time slot 3. . In this case, after completing the set number of time slots, a request command is transmitted again to the wireless tags D and F that have collided, and the same time as described above is transmitted to these wireless tags D and F. Slot assignment processing is performed.

In the present embodiment , the control unit 10 that executes the process of S1 corresponds to an example of a “collision prevention unit”, and prepares slots having the number of slots set by the slot number setting unit and Each wireless tag 50 existing in the readable range is assigned to each slot, and functions to perform a collision prevention process (anti-collision process) that associates each wireless tag 50 with unique identification information.

  After acquiring the unique identification number of each wireless tag 50 by the anti-collision process as described above, wireless communication is performed with the wireless tag 50 to which the unique identification number is attached, and data of each wireless tag 50 is read. Then, data writing to each wireless tag 50 is performed. Then, the processes of S3 and S4 are repeated until the reading of the wireless tag 50 recognized in this way is completed.

  In the present embodiment, the control unit 10, the transmission circuit 20, and the reception circuit 30 correspond to an example of “wireless communication means”, and perform wireless communication with the wireless tag 50 using electromagnetic waves transmitted and received from the antenna 40 as a medium. More specifically, it functions to recognize each wireless tag 50 based on each identification information (unique identification information) associated with each wireless tag 50 by the collision prevention means and to communicate with each wireless tag 50. doing.

  When the process proceeds to No in S3, a process of determining a Q value to be used for the next reading (reading in S4 after increasing the output in S7 by one step) based on the number of tags acquired in the processes in S3 and S4 Is performed (S5). In the process of S5, the wireless tag 50 existing in the reading range based on the number of tags (read tag number) acquired in the processes of S3 and S4 and the transmission output set at the time of reading in S4. The density of is calculated. In the present embodiment, for example, as shown in FIG. 6A, the area of the reading range is determined in advance for each stage of transmission output, and such correspondence data is stored in the memory 13. When a series of processing of S3 and S4 is completed (that is, it is determined that reading has been completed), and the number of tags acquired in S3 and S4 is determined, a transmission output stage in S4 and a series of S3 and S4 The density of the wireless tag 50 in the reading environment can be calculated based on the number of the wireless tags 50 acquired in the process, and the predicted number of tags when the next output is obtained can be calculated based on the calculated density. It has become.

  For example, as shown in FIG. 6B, the output value of the transmission radio wave is P1 of the first stage, the area of the associated reading range is R1, and S3, When the number of wireless tags 50 (number of acquired tags) read in the process of S4 is N1, the density can be calculated as N1 / R1. For the output value P2 set in the next stage, since the area of the reading range is associated with R2, the number of predicted tags is calculated based on the area R2 and the calculated density N1 / R1. R2 × N1 / R1 can be calculated.

  In the present embodiment, the control unit 10 that performs the determination process of S3 corresponds to an example of a reading completion determination unit, and whether or not reading of the wireless tag 50 within the readable range has been completed in the set output stage. To function.

  Further, the control unit 10 that executes the process of S5 corresponds to an example of a prediction unit, and the transmission output set by the output setting unit and the existing values within the readable range until the reading completion determination unit determines that the reading is completed. Based on the number of read tags, the output setting means functions to predict the number of unread tags that fall within the readable range when the transmission output is increased to a new stage.

  Then, after the number of predicted tags is determined as described above, based on the number of predicted tags, the Q value used for reading is determined when the output value is raised to the next stage. In the present embodiment, as shown in FIG. 6C, a table in which a Q value (optimum Q value) is determined in association with the predicted tag number is stored in the memory 13, and the predicted tag number is calculated as described above. If it is, the Q value corresponding to the calculated predicted tag number can be obtained by referring to the table. Note that a table as shown in FIG. 6C can be created based on theoretical values, past experimental results, and the like.

  In the present embodiment, the control unit 10 and the memory 13 correspond to an example of a “slot number setting unit”, and the number of slots used for the anti-collision process is determined by determining the Q value. In addition, as described above, the control unit 10 and the memory 13 corresponding to the “slot number setting unit” set the slot number to a predetermined minimum slot number (for example, 1) at the start of reading by the wireless communication unit and Based on the number of unread tags predicted by the means, it functions to determine the number of slots at the new stage, and furthermore, a table in which the number of tags of unread tags and the number of slots are defined in association with each other, A memory 13 (storage unit) for storing a table, and a function for determining the number of slots at a new stage based on the number of unread tags predicted by the prediction unit and the table stored in the storage unit doing. The predetermined minimum number of slots means a minimum value within the range of the number of slots that can be set by the wireless tag reader.

  After the new Q value is set in S5, it is determined whether or not the set output (maximum output) has been reached (S6). If not, the answer is No in S6 and output. Is increased by one step (S7). And the process after S3 is performed by the setting raised by one step in this way. In this way, until reaching the set output (maximum output), the loop of S3 to S7 is repeated, the output is increased step by step, and each output is read.

On the other hand, if it is determined that the above-described set output (maximum output) has been reached, No in S6 and carrier output is stopped (S10). Then, the user is notified (S11). In the notification in S11, for example, explanation information such as “reading is completed” may be displayed on the display unit 14, and explanation information such as “no readable radio tag is lost” is displayed on the display unit 14. May be. Alternatively, when reading is performed (Yes in S6) and when not reading (Yes in S8), in the case of Yes in S6, “Read wireless tag in readable range” In the case of S8 Yes, the fact that the tag has not been read may be displayed, such as “No tag detected until the maximum reading range”. Further, the display is not limited to this, and for example, sound generation by a sound means (speaker, buzzer, etc.), generation of vibration by a vibration generator, and the like may be used.
In the present embodiment, the control unit 10 and these notification media (such as the display unit 14) correspond to examples of “completion notification unit” and “non-detection notification unit”.

(Main effects of the first embodiment)
The wireless tag reader 1 according to the present embodiment recognizes each wireless tag based on the identification information associated with each wireless tag by the collision prevention means, and performs wireless communication with the wireless tag reader 1 that communicates with each wireless tag. Read completion judging means for judging whether or not the reading of the wireless tag within the readable range is completed, and the transmission output of the electromagnetic wave from the antenna 40 can be switched in a plurality of stages. Output setting means for increasing transmission output to a new stage after determination of completion, transmission output set by output setting means, and read tag within readable range until reading completion is determined by reading completion determination means Predicting means for predicting the number of unread tags that fall within the readable range when the transmission output is increased to a new stage by the output setting means based on the number, It is provided. Then, the slot number setting means determines the number of slots at a new stage based on the number of unread tags predicted by the prediction means.
In this way, the output of the electromagnetic wave from the antenna 40 can be increased stepwise in response to the completion of reading of the wireless tag 50 in S3 and S4. The output is unlikely to be excessive with respect to the 50 arrangement states, and the power consumption can be effectively reduced. Further, when the output is increased to a new stage, the number of slots is determined after predicting a new number of unread tags, so that it is possible to read with a more appropriate number of slots in the new stage.

  Further, in the wireless tag reader 1 according to the present embodiment, the slot number setting unit includes a table in which the number of tags of the unread tag and the number of slots are defined in association with each other, and a storage unit that stores the table. The number of slots at a new stage is determined based on the number of unread tags predicted by the above and the table stored in the storage unit. In this way, the relationship between the number of unread tags and the appropriate number of slots corresponding thereto is prepared as a table based on past experimental data, theoretical values, etc., so that appropriate slots can be used without complicated processing. The number can be determined quickly.

  Further, in the wireless tag reader 1 according to the present embodiment, the output setting unit sets the transmission output to the minimum output among a plurality of stages at the start of reading by the wireless communication unit, and until the wireless tag is detected by the wireless communication unit, The transmission output is gradually increased step by step. In this way, since reading is performed step by step from a lower output, it is possible to effectively save power compared to a configuration in which a high output state continues for a long time from the start of reading.

  Further, in the wireless tag reader 1 according to the present embodiment, the slot number setting means sets the slot number to a predetermined minimum slot number at the start of reading by the wireless communication means. Since the output is set to a lower value at the start of reading, the number of unread tags tends to be lower, and if the number of slots is set to a predetermined minimum number of slots, the value is relatively suitable for the number of unread tags.

  Further, in the wireless tag reader 1 according to the present embodiment, when a plurality of stages of switching by the output setting unit are completed, at least one of display on the display unit, sound generation by the audio unit, and generation of vibration by the vibration generator is executed. Completion notification means is provided. In this way, the gradual switching of the output is completed and the user can be informed that the output will not increase any more. Therefore, the user can quickly grasp when the increase in the output is completed and take appropriate action. It becomes easy to take.

Further, the wireless tag reader 1 according to the present embodiment, switching of a plurality of stages completed by the output setting means, when a new radio tag is not detected, the display by the display unit, the sound output of the audio unit, the vibration due to the vibration generator Non-detection notification means for executing at least one of the occurrences is provided. In this way, the stepwise switching of the output is completed, and the user can be notified that the reading is completed within the maximum reading range. Therefore, the user can quickly grasp that the reading has been completed within the maximum reading range and easily take an appropriate action.

  In the wireless tag reader 1 according to the present embodiment, the wireless communication unit includes a power amplifier 26 that amplifies a transmission signal for the antenna 40, and the output setting unit controls the amplification value of the power amplifier 26. In this way, a configuration in which the output from the antenna 40 can be switched stepwise can be suitably realized.

[Other Embodiments]
The present invention is not limited to the embodiments described with reference to the above description and drawings. For example, the following embodiments are also included in the technical scope of the present invention.

  In the above embodiment, the output value of the transmission radio wave from the antenna 40 is switched stepwise by controlling the amplification value of the power amplifier 36, but the output setting method is not limited to this. For example, a variable attenuator is provided between the modulator 24 and the RF band filter 25, and the amount of attenuation of the variable attenuator is controlled by the control unit 10 to adjust the input voltage to the power amplifier 26. Good. Moreover, you may make it perform amplitude adjustment which changes the amplitude of the modulation signal from a modulator.

  Further, in the wireless tag reader 1 according to the present embodiment, the slot number setting means determines the number of slots at a new stage by a predetermined arithmetic expression using the number of unread tags predicted by the prediction means as a parameter. Also good. For example, a linear function or a quadratic function using the predicted number of slots as a parameter may be generated based on data as shown in FIG. 6C, and the number of slots may be determined by such an arithmetic expression.

DESCRIPTION OF SYMBOLS 1 ... Wireless tag reader 10 ... Control part (Wireless communication means, slot number setting means, collision prevention means, reading completion judgment means, output setting means, prediction means, completion notification means, non-detection notification means)
13: Memory (slot number setting means, storage unit)
14 ... Display section (completion notification means, non-detection notification means)
20 ... Transmission circuit (wireless communication means)
21 ... frequency synthesizer 24 ... modulator 26 ... power amplifier 30 ... receiving circuit (wireless communication means)
40 ... Antenna

Claims (10)

An antenna for transmitting and receiving electromagnetic waves;
Wireless communication means for performing wireless communication with a wireless tag through the electromagnetic wave transmitted and received from the antenna;
Slot number setting means for setting the number of slots;
Preparing the number of slots set by the number-of-slots setting means, assigning each wireless tag existing within the readable range of the wireless communication means to each slot, and assigning each wireless tag to unique identification information Anti-collision means for performing anti-collision processing,
With
The wireless communication means is a wireless tag reader for recognizing each wireless tag based on identification information associated with each wireless tag by the collision preventing means and communicating with each wireless tag;
Reading completion determination means for determining whether reading of the wireless tag within the readable range is completed;
An output setting means configured to switch the transmission output of the electromagnetic wave from the antenna in a plurality of stages, and to increase the transmission output to a new stage after the determination of the reading completion by the reading completion determination means;
It said transmission output set by said output setting means, by the density of the number of the read tags rather based on the number of read tags in the read range of until judged complete read by said reading completion determining means and predicting means for predicting the number of unread tags that fall within the reading range when the transmission power is increased to the new stage by said output setting means,
With
The slot number setting means determines the number of slots at the new stage based on the number of unread tags predicted by the prediction means. The slot number setting means includes
A table in which the number of unread tags and the number of slots are associated with each other,
A storage unit for storing the table;
With
The number of slots at the new stage is determined based on the number of unread tags predicted by the prediction unit and the table stored in the storage unit. Wireless tag reader.     The slot number setting means determines the slot number at the new stage by a predetermined arithmetic expression using the unread tag number predicted by the prediction means as a parameter. Wireless tag reader.   The output setting means sets the transmission output to the minimum output of the plurality of stages at the start of reading by the wireless communication means, and gradually sets the transmission output until the wireless tag is detected by the wireless communication means. The wireless tag reader according to any one of claims 1 to 3, wherein the wireless tag reader is sequentially increased.   5. The wireless tag reader according to claim 4, wherein the slot number setting means sets the slot number to a predetermined minimum number of slots when reading by the wireless communication means is started.   When completion of the switching of the plurality of stages by the output setting means, a completion notification means is provided for executing at least one of display on a display unit, sound generation by a sound means, and generation of vibration by a vibration generator. The wireless tag reader according to any one of claims 1 to 5.   When the switching of the plurality of stages by the output setting unit is completed and a new wireless tag is not detected, at least one of display on the display unit, sound generation by the audio unit, and generation of vibration by the vibration generator is executed. The wireless tag reader according to claim 1, further comprising a detection notification unit. The wireless communication means includes a power amplifier that amplifies a transmission signal to the antenna,
The wireless tag reader according to any one of claims 1 to 7, wherein the output setting unit controls an amplification value of the power amplifier. The wireless communication means includes
An oscillator for generating a carrier wave;
A modulator for modulating the carrier wave generated by the oscillator;
With
The wireless tag reader according to any one of claims 1 to 7, wherein the output setting unit changes an output level of a modulation signal from the modulator. The wireless communication means includes a power amplifier that amplifies a transmission signal to the antenna,
The wireless tag reader according to claim 1, wherein the output setting unit includes a variable attenuator capable of adjusting an input voltage to the power amplifier.

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