JP2011028470A - Radio tag reader and conveyance object management system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radio tag reader and a conveyance object management system for reliably and correctly obtaining the conveyance order of conveyance objects in a route. <P>SOLUTION: When radio tag circuits To attached to conveyance objects C sequentially move along the route, timing that the radio tag circuits To passes through the center position of an area 3 is determined. As a result, even when both a radio tag circuit To having a high communication sensitivity and a radio tag circuit To having a low communication sensitivity move along the route, a preceding radio tag circuit To is detected in a preceding order, and a following radio tag circuit To is detected in a following order. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an RFID circuit reader that detects an IC circuit unit having a storage unit that stores information and a plurality of RFID tag circuit units that have a tag antenna that transmits and receives information, and a transported object management system including the RFID tag reader.

  In recent years, a radio frequency identification (RFID) system that performs transmission and reception of information between a wireless tag circuit unit that stores information and a wireless tag reader has been put into practical use in various fields.

  Some of the above RFID tag readers detect a RFID circuit portion that moves in one direction (see, for example, Patent Document 1). In this prior art, two communication antennas that form an overlapping communication range along the moving direction of the RFID circuit part are provided. Then, by determining which antenna has received the response signal from the RFID circuit unit after the command transmission, the position of the RFID circuit unit at the time of response can be specified.

JP 2009-33517 A

  In general, the RFID tag circuit unit has variations in communication sensitivity due to the performance of the IC chip, the resistance of the mounting portion between the tag antenna and the IC chip, the error in the mounting position, the influence of the physical properties of the object to be attached, etc. . For this reason, even if the output of the communication antenna on the RFID tag reading device side is constant, the communication range is relatively wide for the RFID circuit portion having a high communication sensitivity, and the RFID circuit portion having a low communication sensitivity. In contrast, the communicable range is relatively narrow.

  The same applies to the case where two communication antennas form an overlapping communication range as in the above-described prior art, and the overlapping communication range is relatively wide and the communication sensitivity is low for a radio tag circuit unit having high communication sensitivity. The overlapping communication range is relatively narrow with respect to the wireless tag circuit unit. That is, the size of the overlapping communication range varies depending on the communication sensitivity of the wireless tag circuit unit.

  For this reason, when the RFID circuit unit provided on the transported object sequentially moves along the conveyance path, for example, the RFID circuit unit with the highest communication sensitivity has moved next to the RFID circuit unit with the low communication sensitivity. In such a case, there is a possibility that the latter RFID tag circuit unit whose communication range is wide is detected first. Therefore, even if it is the structure which forms an overlapping communication range like the said prior art, there existed a possibility that the conveyance order of each conveyed product in a conveyance path | route could not be grasped | ascertained correctly.

  An object of the present invention is to provide a wireless tag reader and a transported object management system capable of accurately and correctly grasping the transport order of transported objects on a transport path.

  In order to achieve the above object, a wireless tag reader according to a first aspect of the present invention includes a storage unit that is provided in each of a plurality of transported objects that are sequentially transported in one direction along a predetermined transport path and stores information. A wireless tag reading device that sequentially detects a plurality of wireless tag circuit portions having a tag antenna that transmits and receives information to and from the IC circuit portion, and forms a first communicable range in a predetermined portion of the transport path. A first communication antenna, a second communication antenna that forms a second communicable range that partially overlaps the first communicable range at a portion downstream of the predetermined portion of the transport path in the transport direction; and Switching control means for performing switching control between the first communication antenna and the second communication antenna so that the first communication antenna and the second communication antenna perform communication alternately, and control by the switching control means Based on the presence or absence of a response signal from the wireless tag circuit unit received by the first communication antenna and the second communication antenna that are controlled to be replaced, the wireless tag circuit unit that moves along the transport path, Passage determination means for determining the passage time of the overlapping communication range where the first communicable range and the second communicable range overlap.

  In the first invention of this application, the first communicable range of the first communication antenna and the second communicable range of the second communication antenna are formed along the transport path of the transported object. Moreover, the first communication antenna and the second communication antenna are switched by the switching control means so as to perform communication alternately. Here, the first communicable range of the first communication antenna and the second communicable range of the second communication antenna are partially overlapped to form an overlapping communication range. For this reason, the RFID circuit unit that is moved sequentially by the conveyance, while moving in the overlapping communication range, the signal from the first communication antenna and the signal from the second communication antenna that are switched as described above. It becomes possible to respond to both signals.

  By the way, in general, the RFID tag circuit unit varies in communication sensitivity due to the performance of the IC chip, the resistance of the mounting portion between the tag antenna and the IC chip, the error in the mounting position, the influence of the physical properties of the object to be attached, etc. It is inevitable that this occurs. For this reason, even if the output of the communication antenna on the RFID tag reading device side is constant, the communication range is relatively wide for the RFID circuit portion having a high communication sensitivity, and the RFID circuit portion having a low communication sensitivity. In contrast, the communicable range is relatively narrow. That is, the communicable range from the communication antenna expands and contracts depending on the communication sensitivity of the RFID circuit part.

  The same applies to the case where two communication antennas form an overlapping communication range as in the first invention of the present application. The overlapping communication range is relatively wide for the wireless tag circuit unit having high communication sensitivity, and the overlapping communication range is relatively narrow for the wireless tag circuit unit having low communication sensitivity. That is, the size of the overlapping communication range varies depending on the communication sensitivity of the wireless tag circuit unit. However, the change in the size of the overlapping communication range at this time originally originates from the expansion and contraction of the communicable range from each communication antenna. Therefore, there is a characteristic that the center position of the overlapping communication range when it becomes wider and the center position of the overlapping communication range when it becomes narrower hardly change.

  The first invention of the present application applies this characteristic, and when the RFID circuit portion provided on the transported object sequentially moves along the conveyance path, the passage determining means passes the overlapping communication range of the RFID tag circuit portion. Judge the time. As a result, even when RFID tag units with high communication sensitivity and RFID tag units with low communication sensitivity are mixed and move along the transport path, the preceding RFID circuit unit is always detected in the previous order. At the same time, the succeeding RFID tag circuit section is detected in the later order. That is, it is possible to prevent the wireless tag reading device from erroneously detecting the wireless tag circuit unit in an order different from the order in which it is conveyed. In this way, according to the first invention of the present application, it is possible to reliably grasp the transport order of the transported objects in the transport path by detecting the passage time of the overlapping communication range of each RFID circuit part.

  According to a second aspect of the present invention, there is provided the wireless tag reading device according to the first aspect, wherein the time measuring means for measuring the time when the response signal from the wireless tag circuit unit is received by the first communication antenna and the second communication antenna; Storage means for storing the time counted by the means as communication time, wherein the passage determination means determines the passage time of the overlapping communication range using the communication time stored in the storage means.

  In the second invention of this application, the time of entry to the overlapping communication range of the RFID tag circuit unit is counted and the approaching time is stored by the storage unit, and the time of counting from the overlapping communication range of the RFID tag circuit unit is stored. It is possible to measure the exit time and store the exit time by the storage means. As a result, by determining the intermediate time between the entry time and the exit time stored by the passage determination means, the timing time at which each RFID circuit section passes through the overlapping communication range can be accurately detected.

  According to a third aspect of the present invention, there is provided the wireless tag reader according to the first or second aspect of the invention, wherein the passage determining unit is configured to transmit the communication time stored in the storage unit from the wireless tag circuit unit in the second communication antenna. When the response signal is received from the state in which the response signal is not received, the entry determination means for determining the entry time to the overlapping communication range and the communication time stored in the storage means From the state in which the response signal from the wireless tag circuit unit is received in the first communication antenna, an exit determination unit that determines an exit time from the overlapping communication range when the response signal is not received. And intermediate determination means for determining an intermediate time between the entry time and the exit time.

  The entry determining means determines the entry time of the wireless tag circuit section into the overlapping communication range, and the exit determining means determines the exit time of the wireless tag circuit section from the overlapping communication range. Based on these determination results, an intermediate time between the entry time and the exit time is determined by the intermediate determination means, so that the time when each RFID circuit portion passes the center of the overlapping communication range is detected more accurately. be able to.

  According to a fourth aspect of the present invention, there is provided the wireless tag reader according to any one of the first to third aspects, wherein the first communication antenna and the second communication antenna are the axial center position of the first communication antenna and the second communication antenna. The line connecting the axial center positions of the RFID tag circuits is arranged so as to be parallel to the moving direction of the RFID tag circuit portion in the transport path.

  With this arrangement, the center position of the overlapping communication range where the two communication ranges overlap can be surely made constant regardless of the sensitivity level of the wireless tag circuit unit.

  According to a fifth aspect of the present invention, there is provided the wireless tag reader according to the fourth aspect, wherein the first communication antenna and the second communication antenna are a main lobe direction line of the first communication antenna and a main lobe direction of the second communication antenna. Are arranged so as to intersect with each other on the transport path.

  With this arrangement, it is possible to further increase the size of the overlapping communication range where the two communication ranges overlap.

  According to a sixth aspect of the present invention, there is provided the wireless tag reader according to any one of the first to fifth aspects, wherein the first state for transmitting / receiving information to / from the first communication antenna and the information transmission / reception to / from the second communication antenna are performed. A first switching command for switching from the first state to the second state for the RFID circuit unit storing the switching identifier that can be switched to any of the second states in the storage unit, A first switching command transmitting means for transmitting using a communication antenna and a second switching command for switching from the second state to the first state to the RFID circuit unit using the second communication antenna And a second switching command transmitting means for transmitting.

  As a result, once the RFID circuit unit communicates with the first communication antenna once on the upstream side of the transport path, it no longer communicates with the same first communication antenna, and once communicates with the second communication antenna on the downstream side of the transport path. If it does so, it will no longer communicate with the same second communication antenna. As a result, it is possible to avoid unnecessary communication outside the overlapping communication range as much as possible and improve communication efficiency.

  In order to achieve the above object, a transported object management system according to a seventh aspect of the present invention includes a plurality of IC circuit units each including a storage unit that stores information and wireless tag circuit units each including a tag antenna that transmits and receives information. Forming a first communicable range at a predetermined portion of the transfer path, a transfer means for sequentially transferring the transfer object in one direction along a predetermined transfer path, a transfer control means for controlling the transfer speed of the transfer means, and A second communication antenna that forms a second communicable range that partially overlaps the first communicable range at a portion downstream of the predetermined portion of the transport path in the transport direction, A first time segment is allocated to the communication of the first communication antenna, a second time segment is allocated to the communication of the second communication antenna, and the first communication segment is assigned according to the first time segment and the second time segment. Switching control means for performing switching control between the first communication antenna and the second communication antenna so that the tener and the second communication antenna perform communication alternately, and the first controlled by the control of the switching control means. Based on the presence / absence of a response signal from the RFID tag circuit unit received by the communication antenna and the second communication antenna, the RFID tag circuit unit moving along the carrier path, the first communicable range and the A transported object management system comprising: a wireless tag reader including a passage determination unit that determines a passage time of an overlapping communication range that overlaps with the second communicable range, wherein the transport control unit is configured to transport the transport speed of the transport unit. Is the first transport speed, the passage time of the overlapping communication range of one RFID tag circuit unit determined by the passage determination unit, and the communication speed The time difference with the passing time of the overlapping communication range of the RFID tag circuit unit different from the one RFID tag circuit unit determined by the determination unit is more than the sum of the first time segment and the second time segment. When it is smaller, it comprises a reduction control means for controlling the transport speed of the transport means so as to be lower than the first transport speed.

  In the seventh invention of the present application, when the first communication antenna and the second communication antenna are switched by the switching control means and try to communicate with the wireless tag circuit unit alternately, the first communication antenna has the first time section as the time. The second communication antenna has a second time segment as time. As a result, the maximum detection error that can occur when the RFID tag circuit unit is detected is the sum of the first time segment and the second time segment. Therefore, if the passage time in the overlapping communication range of the two RFID circuit sections determined by the passage determination means is smaller than the sum of these two time sections, the detection resolution is exceeded and the transport order of the transported objects is detected correctly. It may not have been.

  Therefore, in such a case, the decrease control means provided in the transport control means decreases the transport speed of the transport means. Thereby, after that, the passage time in the overlapping communication range of the two RFID circuit sections determined by the passage determination means can be made larger than the sum of the first time segment and the second time segment. As a result, it is possible to reliably detect the transport order of the transported object.

  In the transported material management system according to an eighth aspect of the present invention, in the seventh aspect of the present invention, the transport control means is configured such that the time difference when the transport speed of the transport means is the second transport speed is not less than three times the first time interval. Or an increase control means for controlling the transport speed of the transport means to be higher than the second transport speed when the second time interval is three times or more. .

  As described above, the maximum detection error at the time of detection is the sum of the first time segment and the second time segment, and it is correct if the transit time in the overlapping communication range of the two RFID tag circuit units is smaller than the two sums. Detection may not be possible. However, if the transit time in the overlapping communication range of the two RFID tag circuit units is larger than three times the first time segment and the second time segment, the margin for the detection resolution is too large, and the interval between the transported objects is It's too wasted.

  Therefore, in the eighth invention of the present application, in such a case, the reduction control means provided in the transport control means decreases the transport speed of the transport means. As a result, the above-described waste can be eliminated, and an efficient transport sequence can be detected.

  In order to achieve the above object, a transported object management system according to a ninth aspect of the present invention includes a plurality of IC circuit units each including a storage unit that stores information and wireless tag circuit units each including a tag antenna that transmits and receives information. Forming a first communicable range at a predetermined portion of the transfer path, a transfer means for sequentially transferring the transfer object in one direction along a predetermined transfer path, a transfer control means for controlling the transfer speed of the transfer means, and A second communication antenna that forms a second communicable range that partially overlaps the first communicable range at a portion downstream of the predetermined portion of the transport path in the transport direction, A first time segment is allocated to the communication of the first communication antenna, a second time segment is allocated to the communication of the second communication antenna, and the first communication segment is assigned according to the first time segment and the second time segment. Switching control means for performing switching control between the first communication antenna and the second communication antenna so that the tener and the second communication antenna perform communication alternately, and the first controlled by the control of the switching control means. Based on the presence / absence of a response signal from the RFID tag circuit unit received by the communication antenna and the second communication antenna, the RFID tag circuit unit moving along the carrier path, the first communicable range and the And a RFID tag reader having passage determination means for determining passage times of overlapping communication ranges that overlap with a second communicable range, wherein the switching control means includes the first time section and While the second time interval is increased or decreased, the first communication antenna and the second communication antenna communicate alternately according to the increased or decreased first time interval and second time interval. As performed, and performs switching control of their first communication antenna and the second communication antenna.

  In the ninth invention of this application, when the transport speed of the transport means is the first transport speed, the time difference between the passage time of one RFID circuit section and the passage time of another RFID circuit section is the first time section. If the sum is smaller than the sum of the second time segments, the switching control means decreases the first time segment and the second time segment to make the time difference larger than the sum of the first time segment and the second time segment. It is possible. As a result, it is possible to correctly detect the transport order of transported objects without changing the transport speed of the transport means.

  According to the present invention, it is possible to accurately grasp the transport order of the transported objects on the transport path.

It is a system configuration figure showing the outline of the reader of this embodiment. It is a block diagram showing an example of a functional structure of the wireless tag circuit part with which the wireless tag was equipped. It is a figure showing an example of the time chart of the signal transmitted / received between the 1st antenna of a reader, the 2nd antenna, and a RFID circuit part. It is a figure for demonstrating the principle which can detect the conveyance order of a conveyed product correctly, even when there exists dispersion | variation in the communication sensitivity of each RFID circuit part. It is a figure for demonstrating the method of determining the passage timing of the center position of the area | region of a RFID circuit part in the case of high sensitivity and the case of low sensitivity. It is a flowchart showing the control content performed by the control circuit of a reader. It is a flowchart showing the detailed content of step S100 which is a communication process by a 1st antenna. It is a flowchart showing the detailed content of step S200 which is a communication process by a 2nd antenna. It is a system configuration | structure figure showing the outline of the reader | leader of the modification which expands the range of an overlapping communication possible area | region. It is a system block diagram showing the outline of the conveyed product management system of the modification which performs the conveyance speed control of a belt conveyor. It is a flowchart showing the control content performed by the control circuit of a reader in the modification which performs conveyance speed control of a belt conveyor. It is a flowchart showing the other control content performed by the control circuit of a reader in the modification which performs conveyance speed control of a belt conveyor.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a system configuration diagram illustrating an outline of a reader 100 according to the present embodiment.

  The reader 100 (wireless tag reader) sequentially detects the wireless tags T provided on each of the plurality of transported objects C that are sequentially transported in one direction along a predetermined transport path by the belt conveyor BC, and each transported object. This is for managing the conveyance order of C. The wireless tag T includes a wireless tag circuit unit To including an IC circuit unit 150 including a memory unit 155 to store information and a tag antenna 151 for transmitting and receiving information.

  The reader 100 includes a reader body 10 and a first antenna A and a second antenna B. The first antenna A (first communication antenna) forms a first communicable region 21 (first communicable range) in a predetermined portion of the transport path of the transported object C, and the second antenna B (second communication antenna). Forms a second communicable region 22 (second communicable range) that partially overlaps the first communicable region 21 at a portion of the transport route downstream of the first communicable region 21 in the transport direction. In the overlapping communicable region 23 (overlapping communication range) in which the first communicable region 21 and the second communicable region 22 overlap, both the first antenna A and the second antenna B can detect the wireless tag T. It is. Hereinafter, the area excluding the overlapping communicable area 23 from the first communicable area 21 is “area 1”, the area excluding the overlapping communicable area 23 from the second communicable area 22 is “area 2”, and the overlapping communicable area An area corresponding to 23 is referred to as “area 3”.

  In the first antenna A and the second antenna B, the line or plane L1 connecting the axial center position of the first antenna A and the axial center position of the second antenna is the RFID circuit part To in the transport path by the belt conveyor BC. It is arrange | positioned so that it may become parallel to the moving direction of. The axis position is an example of the reference position of the antenna. For example, when the first antenna A and the second antenna B are a loop antenna or a coil antenna, the position of the axis of the coil is expressed.

  The reader main body 10 includes a control circuit 11, a high frequency circuit 12, a changeover switch 13, a timer unit 14, and a storage unit 15. The control circuit 11 processes the signal read from the IC circuit unit 150 of the RFID tag circuit unit To and reads information, and generates various commands for accessing the IC circuit unit 150 of the RFID tag circuit unit To. . The high frequency circuit 12 accesses the information of the IC circuit unit 150 of the RFID circuit unit To via the first antenna A or the second antenna B based on the various commands. The changeover switch 13 switches the antennas A and B so that the first antenna A and the second antenna B perform communication alternately based on the control of the control circuit 11. The switching timing between the first antenna A and the second antenna B is set in advance.

  The time measuring unit 14 (time measuring means) measures the timing at which the first antenna A and the second antenna B receive tag information as a response signal from the wireless tag circuit unit To. The storage unit 15 (storage unit) stores the timing measured by the timer unit 14 as a communication timing. The timing measured by the time counting unit 14 and stored in the storage unit 15 corresponds to the communication time described in the claims, and may be a relative time from a predetermined reference time or a time. Good.

  The control circuit 11 uses the communication timing stored in the storage unit 15 based on the presence / absence of a response signal from the RFID tag circuit unit To received by the first antenna A and the second antenna B to be switched, The passage timing of the center position of the area 3 of the RFID circuit portion To moving along the transport path is determined. Details of this determination will be described later.

  FIG. 2 is a block diagram illustrating an example of a functional configuration of the RFID tag circuit unit To provided in the RFID tag T.

  In FIG. 2, the RFID circuit unit To includes a tag antenna 151 that transmits and receives signals without contact with the first antenna A or the second antenna B of the reader 100 and an IC connected to the tag antenna 151 as described above. Circuit portion 150.

  The IC circuit unit 150 includes a rectification unit 152 that rectifies the interrogation wave received by the tag antenna 151, a power supply unit 153 that accumulates the energy of the interrogation wave rectified by the rectification unit 152 and uses it as a drive power source, A clock extraction unit 154 that extracts a clock signal from the interrogation wave received by the antenna 151 and supplies the clock signal to the control unit 157, a memory unit 155 (storage unit) that can store a predetermined information signal, and a tag antenna 151 are connected. A modulation / demodulation unit 156, a random number generator 158 that generates a random number for determining which identification slot the RFID circuit unit To outputs a response signal when receiving a response request command from the reader 100, and the memory Operation of the RFID circuit unit To through the unit 155, the clock extraction unit 154, the random number generator 158, the modem unit 156, etc. And a control unit 157 for controlling.

  The modulation / demodulation unit 156 demodulates the interrogation wave from the first antenna A or the second antenna B of the reader 100 received by the tag antenna 151, modulates the return signal from the control unit 157, and receives the signal from the tag antenna 151. Transmit as response wave.

  The clock extraction unit 154 extracts a clock component from the received signal and supplies a clock corresponding to the frequency of the clock component to the control unit 157.

The random number generator 158 generates a random number from 0 to 2 ^Q −1 for the slot number designation value Q designated in the response request command from the reader 100.

  The control unit 157 interprets the received signal demodulated by the modem unit 156, generates a return signal based on the information signal stored in the memory unit 155, and converts the return signal into the random number generated by the random number generator 158. Basic control such as control of returning from the tag antenna 151 by the modulation / demodulation unit 156 is executed in the corresponding identification slot.

  The memory unit 155 stores an inventory flag (switching identifier) for determining the inventory state at that time so that the contents can be automatically reversed. Here, the inventory state represents the communication state of the RFID circuit unit To at that time. In this embodiment, the contents of the inventory flag of the RFID circuit unit To are two types, “A” and “B”. From the contents of the inventory flag, it can be determined whether or not the RFID circuit part To has completed the inventory. Instead of storing the inventory flag in the memory unit 155 as described above, a register in the control unit 157 may be used to perform a substantially equivalent function.

  Here, in the reader 100 of this embodiment, in each wireless communication by the first antenna A and the second antenna B, the tag information is requested only to the RFID circuit unit To whose contents of the inventory flag are different from each other. To do. That is, in the case of wireless communication using the first antenna A, a command requesting tag information is transmitted only to the RFID circuit unit To whose content of the inventory flag is “A”. In the case of wireless communication using the second antenna B, a command requesting tag information is transmitted only to the RFID circuit unit To whose content of the inventory flag is “B”. Note that the state where the content of the inventory flag is “A” corresponds to the first state described in the claims, and the state where the content of the inventory flag is “B” corresponds to the second state. Next, the details will be described.

  FIG. 3 is a diagram illustrating an example of a time chart of signals transmitted and received between the reader 100 and the wireless tag circuit unit To. FIG. 3A illustrates a case where wireless communication is performed by the first antenna A. FIG. (B) has shown the case where the wireless communication by the 2nd antenna B is performed. The signal transmission / reception method shown in FIG. 3 conforms to the EPC global Class-I Generation-II standard based on the well-known Random-Slotted Collation arbitration method. Shows that the series changes. An arrow written between the reader 100 and the RFID tag circuit unit To indicates the signal transmission direction. When the transmission partner is unspecified, it is indicated by a broken line, and the transmission partner is specified. In this case, it is indicated by a solid line.

  First, the case of wireless communication using the first antenna A will be described with reference to FIG. In FIG. 3A, the reader 100 first issues a “Select” command to the RFID tag circuit units To of all RFID tags T existing in the first communicable area 21 including the areas 1 and 3. Send. This “Select” command is a command for designating the conditions of the RFID tag circuit unit To with which the reader 100 performs radio communication thereafter. Here, the RFID tag circuit unit To whose inventory flag content is “A” is designated. To do. As a result, only the RFID tag circuit section To whose inventory flag content is “A” is in a state where radio communication can be performed thereafter.

  In the present embodiment, for example, all the RFID circuit units To that first enter the area 1 by changing the contents of the inventory flag of each RFID circuit unit To by a wireless communication device (not shown) in advance. The contents of the inventory flag are unified as “A”.

Next, the reader 100 transmits a “Query” command requesting the RFID tag circuit unit To to transmit the tag information as a response. This “Query” command includes a slot number designation value Q designated by a predetermined number. When a “Query” command is transmitted from the high-frequency circuit 12 via the first antenna A, each RFID circuit unit To generates random numbers from 0 to 2 ^Q −1 (= 2 to the power of Q−1) as a random number generator 158. Is generated and held as the slot count value SC.

  In addition, with this “Query” command, the RFID circuit unit To requesting a response can be limited by the contents of the inventory flag. Here, the “Query” command requests a response only to the RFID circuit portion To whose inventory flag content is “A”, and the content of the inventory flag is “A” as shown in the figure. The RFID circuit part To that is responding to the reader 100 thereafter.

After transmitting the “Query” command, the reader 100 waits for a response from the RFID circuit unit To in a predetermined identification slot. The identification slot is a time frame that is divided by a predetermined period from the first transmission of the “Query” command or the “QueryRep” command described later. The identification slot is normally repeated continuously 2 ^Q times, which is obtained by adding 2 ^Q −1 times of the second and subsequent identification slots of the “QueryRep” command to one time of the first identification slot of the “Query” command.

  Then, as shown in the example shown in the figure, the RFID tag circuit section To that generates the value 0 as the slot count value SC responds with the first identification slot including this “Query” command. At this time, the RFID circuit section To transmits a “RN16” response using, for example, a 16-bit pseudorandom number for obtaining permission to transmit tag information to the reader 100 as a response signal.

  Then, the reader 100 that has received the “RN16” response transmits an “Ack” command that permits transmission of tag information with contents corresponding to the “RN16” response. When the RFID circuit unit To that has received the “Ack” command determines that the “RN16” response transmitted by the RFID circuit unit To itself and the received “Ack” command correspond to each other, The tag information is transmitted assuming that the individual RFID tag circuit unit To is permitted to transmit the tag information. This tag information includes a tag ID. In this way, transmission / reception of signals in one identification slot is performed.

  Thereafter, in the second and subsequent identification slots, the reader 100 transmits a “QueryRep” command instead of the “Query” command, and waits for a response from another RFID circuit unit To in the identification slot time frame provided immediately thereafter. . At this time, in the RFID tag circuit section To of the RFID tag T having specifications conforming to the EPC global Class-I Generation-II standard, the contents of the inventory flag differ from the previous one when the “QueryRep” command is received. The above “Select” command can be used to automatically reverse and change to other contents. Here, the RFID circuit unit To that has received the “QueryRep” command automatically inverts the content of the inventory flag that has been “A” until then to the other “B”. As a result, even if a “Query” command or a “QueryRep” command for specifying the contents of the inventory flag with “A” is received thereafter, a standby state in which no response operation is performed is set.

  This “QueryRep” command can also limit the RFID tag circuit section To requesting a response with the contents of the inventory flag. Then, in each RFID circuit unit To that has received this “QueryRep” command, the one with the same inventory flag subtracts and holds only one of the slot count value SC of itself. Signals such as an “RN16” response are transmitted to and received from the reader 100 in the identification slot when the value becomes zero.

  If there is no RFID tag circuit section To corresponding to each identification slot, that is, if there is no slot count value SC of 0 in the identification slot, no transmission / reception other than the “Query” command or the “QueryRep” command is performed. The identification slot is terminated in a predetermined time frame. In addition, the timing is appropriately adjusted so that the time interval between a plurality of commands to be transmitted and received is an appropriate interval.

  In this way, each RFID circuit unit To returns a response signal in a different identification slot, so that the reader 100 receives tag information of each RFID circuit unit To via the first antenna A without receiving interference. Clearly receive and capture. Also, even if the same RFID tag circuit unit To receives the “Query” command specifying the same inventory flag content multiple times, it will receive it after it can respond to the “Query” command normally only once. Since it does not respond to the “Query” command to be performed, it is possible to prevent the same RFID circuit unit To from repeatedly repeating transmission of tag information.

  Next, the case of wireless communication using the second antenna B will be described with reference to FIG. In the case of wireless communication using the second antenna B, the signal transmission / reception contents are the same as those of the first antenna A described above except that the correspondence relationship of the inventory flags is reversed. That is, in the wireless communication using the second antenna B, first, the “Select” command is transmitted to the wireless tag circuit units To of the wireless tags T existing in the second communicable area 22 including the area 2 and the area 3. , The RFID tag circuit portion To whose inventory flag content is “B” is designated. As a result, only the RFID tag circuit section To whose inventory flag content is “B” is in a state where radio communication can be performed thereafter. In the present embodiment, as described above, the content of the inventory flag of the RFID tag circuit section To is reversed from “A” to “B” by wireless communication with the first antenna A in the area 1, so The content of the inventory flag of the RFID circuit portion To entering the area 3 is “B”.

  Then, a response is made to the RFID circuit unit To whose inventory flag is “B” by the “Query” command, and the corresponding RFID circuit unit To responds to the reader 100. After that, the reader 100 that has received the “RN16” response transmits an “Ack” command, and receives tag information from the RFID circuit unit To that has received this “Ack” command. Thereafter, the reader 100 transmits a “QueryRep” command in the second and subsequent identification slots, and the RFID circuit unit To that has received this “QueryRep” command displays the contents of the inventory flag that has been “B” until then. It is automatically reversed to “A”. As a result, even if a “Query” command or a “QueryRep” command that specifies the contents of the inventory flag by “B” is received thereafter, a standby state in which no response operation is performed is set.

  The reader 100 having the above-described configuration detects the transport order of the transported objects C by determining the passage timing of the substantially center position of the area 3 of the RFID circuit part To moving along the transport path. Next, this detailed content is demonstrated.

  First, by determining the passage timing of the center position of the area 3 of the RFID tag circuit section To, even when the communication sensitivity of each RFID circuit section To varies, it is possible to accurately detect the conveyance order of the conveyance object C. Explain a certain principle.

  FIG. 4 is a diagram for explaining this principle. FIG. 4A shows a case of the RFID circuit unit To having a relatively high sensitivity, and FIG. 4B shows a case of the RFID circuit unit To having a relatively low sensitivity. Shows the case.

  In general, the RFID circuit portion To has a communication sensitivity that depends on the performance of the IC chip 150, the resistance of the attachment portion between the tag antenna 151 and the IC chip 150, the error in the attachment position, the physical property of the object to be attached, and the like. Variation occurs. For this reason, even if the output of the communication antenna on the reader side is constant, the communicable area is relatively wide for the RFID circuit unit To having high communication sensitivity, and the RFID circuit unit To having low communication sensitivity is used. On the other hand, the communicable area is relatively narrow. That is, the communicable area from the communication antenna expands and contracts depending on the communication sensitivity of the RFID circuit portion To.

  The same applies to the case where the two antennas A and B form the overlapping communicable region 23 as in the present embodiment. That is, as shown in FIG. 4A, for the RFID circuit part To having a high communication sensitivity, the communicable areas 21 and 22 of the first antenna A and the second antenna B are widened, so that there is an overlap. As shown in FIG. 4B, the communication of the first antenna A and the second antenna B is performed for the RFID circuit unit To having a relatively wide area 3 and a low communication sensitivity. Since the possible areas 21 and 22 are narrowed, the range of the area 3 that is an overlapping area becomes relatively narrow. That is, the size of the area 3 varies depending on the communication sensitivity of the RFID tag circuit section To. However, the change in the size of the area 3 at this time originates from the expansion and contraction of the communicable area from each of the antennas A and B. Therefore, as shown by the center line L2 shown in FIG. 4, there is a characteristic that the center position of the area 3 when it becomes wide and the center position of the area 3 when it becomes narrow hardly change.

  FIG. 5 is a diagram for explaining a method of determining the passage timing of the center position of the area 3 of the RFID tag circuit unit To, and FIG. 5A illustrates the case of the RFID circuit unit To having a relatively high sensitivity. FIG. 5B shows the case of the RFID circuit part To having a relatively low sensitivity. In the figure, the time series changes from left to right.

  In FIG. 5A and FIG. 5B, antennas “A” and “B” indicate communication by the first antenna A and the second antenna B, respectively. Switching control is performed so that the antenna B communicates alternately. The communication range is the above-described areas 1 to 3 formed by the first antenna A and the second antenna B. As shown in FIG. 5A and FIG. The size of each area is larger than that of the RFID tag circuit section To having a lower sensitivity. IF is the content of the inventory flag stored in the RFID circuit section To, and as described above, there are two types of states “A” and “B”. The communication timing is the timing when the tag information is read from the RFID circuit section To, that is, the timing when the reader 100 receives the tag information from the RFID circuit section To that has received the “Ack” command as described above.

  First, the case of the highly sensitive RFID tag circuit portion To will be described. In FIG. 5A, the contents of the inventory flag of the RFID circuit portion To that first enters the area 1 has “A” as described above. When the RFID circuit portion To enters the area 1, only the communication with the first antenna A is performed in the area 1, so that tag information is not read during the communication by the second antenna B. Thereafter, when switching to communication by the first antenna A, the tag information of the RFID circuit section To is read, and the contents of the inventory flag are inverted from “A” to “B”. This timing is measured by the timer unit 14 and stored in the storage unit 15 as the first communication timing. As a result, the RFID circuit section To responds even if it receives a “Query” command or a “QueryRep” command that designates the contents of the inventory flag as “A” by communication with the first antenna A in the area 1 thereafter. No action is taken. Note that there is a slight shift due to a response delay of the RFID tag circuit section To between the switching timing from the second antenna B to the first antenna A and the communication timing.

  Thereafter, when the RFID tag circuit section To whose content of the inventory flag is “B” enters the area 3, communication with both the first antenna A and the second antenna B is performed in the area 3. Here, first, tag information is read by communication by the second antenna B, and the contents of the inventory flag are inverted from “B” to “A”. This timing is measured by the timer unit 14 and stored in the storage unit 15 as the second communication timing. After that, when switching to communication by the first antenna A, tag information is read by communication by the first antenna A, and the contents of the inventory flag are inverted from “A” to “B”. This timing is measured by the timer unit 14 and stored in the storage unit 15 as the third communication timing. In this way, antenna switching in the area 3 is continuously performed, and the contents of the inventory flag are continuously inverted.

  Thereafter, in this example, the tag information is read for the seventh time by communication with the first antenna A, and the RFID tag circuit section To is in the area 2 with the contents of the inventory flag inverted from “A” to “B”. Enter inside. Since only communication with the second antenna B is performed in the area 2, the tag information is read by communication with the second antenna B, and the content of the inventory flag is inverted from “B” to “A”. This timing is measured by the timer unit 14 and stored in the storage unit 15 as the eighth communication timing. As a result, the RFID circuit portion To responds even if it receives a “Query” command or a “QueryRep” command that specifies the contents of the inventory flag by “B” by communication with the second antenna B in the area 2 thereafter. No action is taken. As a result, the RFID circuit unit To exits outside the area 2 with the content of the inventory flag being “A”.

  In the situation as described above, the reader 100 determines that the second communication timing is the entry timing to the area 3 of the RFID tag circuit unit To from among the communication timings stored in the storage unit 15, and the eighth communication timing. Is the exit timing of the RFID tag circuit section To from the area 3, and based on these determination results, an intermediate timing between the entry timing and the exit timing is determined as the passage timing of the center position of the area 3. That is, in the above example, the fifth communication timing, which is the center of the seven communication timings of the second to eighth times, is determined as the passage timing of the center position of the area 3. In FIG. 5A, the communication timing determined as the passage timing of the center position of the area 3 is illustrated by a black triangle.

  Next, the case of the RFID circuit unit To having a low sensitivity will be described. In FIG. 5B, when the RFID circuit unit To enters the area 1, the tag information of the RFID circuit unit To is read by communication by the first antenna A, and the contents of the inventory flag are changed from “A”. Inverted to “B”. This timing is measured by the timer unit 14 and stored in the storage unit 15 as the first communication timing. Thereafter, as described above, no response operation is performed even if a “Query” command or a “QueryRep” command for specifying the content of the inventory flag by “A” is received in the area 1 by communication with the first antenna A. .

  After that, when the RFID tag circuit section To whose inventory flag content is “B” enters the area 3, tag information is read by communication using the second antenna B, and the inventory flag content is changed from “B”. Inverted to “A”. This timing is measured by the timer unit 14 and stored in the storage unit 15 as the second communication timing. After that, when switching to communication by the first antenna A, tag information is read by communication by the first antenna A, and the contents of the inventory flag are inverted from “A” to “B”. This timing is measured by the timer unit 14 and stored in the storage unit 15 as the third communication timing. In this way, antenna switching in the area 3 is continuously performed, and the contents of the inventory flag are continuously inverted.

  Thereafter, in this example, the tag information is read for the fourth time by communication using the second antenna B, and the RFID tag circuit section To is in the area 2 in a state where the contents of the inventory flag are inverted from “B” to “A”. Enter inside. Since only communication with the second antenna B is performed in the area 2, the RFID circuit unit To in which the content of the inventory flag is “A” by reading the tag information for the fourth time described above, No reading is performed. As a result, the RFID circuit portion To exits outside the area 2 while keeping the contents of the inventory flag in the area 2 in the “A” state.

  In the situation as described above, the reader 100 determines that the second communication timing is the entry timing of the RFID tag circuit section To to the area 3 from the communication timings stored in the storage unit 15 and the fourth communication timing. Is the exit timing of the RFID tag circuit section To from the area 3, and based on these determination results, an intermediate timing between the entry timing and the exit timing is determined as the passage timing of the center position of the area 3. That is, in the above example, the third communication timing that is the center of the three communication timings of the second to fourth times is determined as the passage timing of the center position of the area 3. In FIG. 5B, similarly to the above, the communication timing determined as the passage timing of the center position of the area 3 is illustrated by a black triangle.

  By determining the passage timing of the center position of the area 3 as described above, the center position of the area 3 hardly changes regardless of the sensitivity of the RFID tag circuit section To as shown in FIG. Therefore, the preceding RFID circuit unit To can be detected in the previous order, and the succeeding RFID circuit unit To can be detected in the later order. That is, even when the RFID tag circuit unit To having a high communication sensitivity and the RFID tag circuit unit To having a low communication sensitivity are mixed and move along the conveyance path, it is possible to correctly grasp the conveyance order of the conveyance objects C. it can.

  Note that when determining the passage timing of the center position of the area 3, the maximum detection error that can occur when the RFID tag circuit unit To is detected is the communication time ΔT (first time segment) by the first antenna A and It is the sum of the communication time ΔT (second time interval) by the second antenna B, that is, twice the ΔT. Therefore, when the time difference between the passage timings at the center position of the area 3 of the two consecutive RFID tag circuit portions To is smaller than twice the communication time ΔT, the detection resolution is exceeded and the transport order of the transported object C is correctly set. Since there is a possibility that it cannot be detected, the transport speed of the transport object C and the transport object C by the belt conveyor BC are set so that the time difference between the passage timings of the two RFID tag circuit parts To is greater than twice the communication time ΔT. By setting the transport interval, it is possible to correctly grasp the transport order of the transported objects C regardless of the presence or absence of the determination error.

  FIG. 6 is a flowchart showing the control contents executed by the control circuit 11 of the reader 100.

  In step S10, the control circuit 11 performs initial setting of necessary parameters related to wireless communication, such as setting of switching timing of the first antenna A and the second antenna B.

  In step S100, the control circuit 11 switches the changeover switch SW to the first antenna A side, and performs communication processing by the first antenna A.

  In step S200, the control circuit 11 switches the changeover switch SW to the second antenna B side and performs communication processing by the second antenna B.

  In step S <b> 20, the control circuit 11 determines whether or not there is a wireless tag circuit unit To that cannot read the tag information. Here, the RFID tag circuit unit To, which cannot read the tag information, responds when the tag information is read once in the area 1 and the contents of the inventory flag are inverted from “A” to “B”. The tag circuit is read in the RFID tag circuit unit To that is no longer in operation and the content of the inventory flag is inverted from “B” to “A”, or when entering the area 2, the inventory flag The content of “A” indicates two types of RFID tag circuit parts To and RFID tag circuit parts To that have stopped responding in area 2. If there is no RFID circuit part To in the communicable area, the determination is not satisfied and the routine goes to Step S50 described later. On the other hand, when any one of the RFID tag circuit portions To exists in the communicable area, the determination is satisfied, and the routine goes to Step S30.

  In step S30, the control circuit 11 determines whether or not the tag count of the RFID circuit part To determined to be present in step S20 is -1. Here, the tag count is a count value that is set to -1 at the first communication in area 1 and is incremented by 1 each time communication is performed thereafter. That is, if the tag count is −1 in this step, the RFID circuit unit To that has become unable to read tag information is the RFID circuit unit To that has stopped responding in the area 1 described above. Correspondingly, it means that the communication timing counting in areas 1 to 3 is not completed. On the other hand, if the tag count is not -1, this corresponds to the case where the RFID circuit unit To that has become unable to read the tag information is the RFID circuit unit To that has stopped responding in the above-described area 2, and the area This means that the communication timing counting in 1 to 3 has been completed. If the tag count is -1, the determination is satisfied and the routine goes to Step S50 described later. On the other hand, if the tag count is not -1, the determination is not satisfied and the routine goes to Step S40.

  In step S40, the control circuit 11 outputs the time corresponding to the value obtained by dividing the tag count value by 2 because the counting of the communication timing in the areas 1 to 3 has been completed as described above. This output result is stored in, for example, an appropriate storage unit, and is used for determining the conveyance order of the conveyed product C.

  Here, the reason why the passage timing of the center position of the area 3 can be determined by dividing the tag count value by 2 will be described. As shown in FIG. 5 described above, in the present embodiment, the content of the inventory flag of the RFID tag circuit section To is initially “A”, and is always always “A”. Therefore, the total number of communication timings in areas 1 to 3 is an even number. Here, since the first communication timing is performed at the time of first entering the area 1, it is necessary to exclude it when determining the passage timing of the center position of the area 3. Therefore, the timing corresponding to the odd number of centers, which is a value obtained by subtracting 1 from the total number of communication timings that are even numbers, is the passage timing of the center position of the area 3.

  In the present embodiment, as described above, it is possible to obtain the odd number of centers by setting the initial value of the tag count to −1 and dividing the count result by 2. For example, in the example shown in FIG. 5A described above, since the total number of communication timings is 8, the tag count starts from −1 and 6 is the final value. Therefore, the fifth communication timing corresponding to the tag count 3 is the passage timing of the center position of the area 3. In the example shown in FIG. 5B, since the total number of communication timings is 4, the tag count starts from -1 and 2 is the final value. Therefore, the third communication timing corresponding to the tag count 1 is the passage timing of the center position of the area 3.

  In step S50, the control circuit 11 determines whether or not to end the communication process. This determination is performed, for example, based on whether or not an instruction input for ending the communication process has been made by the operator. If the communication process is not terminated, the determination is not satisfied and the routine returns to the previous step S100. On the other hand, when ending the communication process, the determination is satisfied and this flow is ended.

  In the above, step S100, step S200, and step S50 constitute the switching control means described in the claims. Further, step S20 and step S30 constitute an exit determination means, step S40 constitutes an intermediate determination means, and these step S20, step S30 and step S40, and step S225 shown in FIG. Configure the means.

  FIG. 7 is a flowchart showing the detailed contents of step S100, which is communication processing by the first antenna A.

  In step S105, the control circuit 11 switches the changeover switch SW to the first antenna A side, and turns on the RFID circuit units To of all the RFID tags T existing in the first communicable area 21 including the areas 1 and 3. On the other hand, a “Select” command is transmitted. As a result, only the RFID tag circuit section To whose inventory flag content is “A” is in a state where radio communication can be performed thereafter. Further, in the “select” command, it is specified that the contents of the inventory flag are automatically reversed when the tag ID is read.

  In step S110, the control circuit 11 sets the value of the slot number designation value Q to Qmax. This set value Qmax is a parameter for setting how many identification slots the tag information is detected in the communication process by the first antenna A. The set value Qmax is set in advance according to the size of the communicable areas 21 and 22 of the antennas A and B and the number of RFID tag circuit portions To that are expected to be capable of wireless communication. .

  In step S115, the control circuit 11 sends the tag information as a response to the RFID circuit part To having the inventory flag content “A” existing in the first communicable area 21 including the areas 1 and 3. Send a “Query” command requesting that The “Query” command includes the slot number designation value Qmax set in step S110.

  In step S120, the control circuit 11 initializes a variable n for counting the number of slots to 1.

  In step S125, the control circuit 11 determines whether or not the “RN16” response is normally received as a response signal from the RFID circuit section To during a predetermined reception time corresponding to the identification slot. If the “RN16” response is not normally received, it is considered that there is no RFID tag circuit section To responding in the identification slot, and the determination is not satisfied, and the routine goes to Step S155 described later. On the other hand, if the “RN16” response is normally received, it is assumed that there is a wireless tag circuit unit To responding in the identification slot, the determination is satisfied, and the routine goes to Step S130.

  In step S130, the control circuit 11 has a content corresponding to the “RN16” response received in step S115 to the RFID circuit part To existing in the first communicable area 21 including the areas 1 and 3. An “Ack” command that permits transmission of tag information is transmitted.

  In step S135, the control circuit 11 receives the tag information returned from the RFID tag circuit section To in response to the “Ack” command, and reads the already-read RFID tag circuit section based on the tag ID included in the tag information. It is determined whether or not it is To. The control circuit 11 stores the tag ID read for the first time in an appropriate storage means, and the determination is made by comparing the acquired tag ID with the stored tag ID. If the tag ID is read for the first time, it is regarded as the first communication in the area 1 for the RFID circuit part To, and the determination is not satisfied, and the routine goes to Step S140.

  In step S140, the control circuit 11 sets the above-described tag count to -1. Thereafter, the process proceeds to step S155 described later.

  On the other hand, if the tag ID has already been read in step S135, it is regarded as a plurality of times of communication in the area 3 and subsequent times for the RFID circuit part To, and the determination is satisfied, and the routine goes to step S145.

  In step S145, the control circuit 11 adds 1 to the value of the tag count. In step S150, the control circuit 11 acquires time information from the timer unit 14, and stores it in the storage unit 15 as a communication time corresponding to the tag count. .

In step S155, the control circuit 11 determines whether or not the variable n for counting the number of slots is 2 ^Q. If the number of slots does not reach the 2 ^Q proceeds to step S160 the determination is not satisfied.

  In step S160, the control circuit 11 adds 1 to the variable n, and in step S165, the control circuit 11 includes the inventory that exists in the first communicable area 21 including area 1 and area 3 in the next identification slot. A “QueryRep” command is transmitted to the RFID circuit unit To whose flag content is “A”. And it returns to previous step S125. The “QueryRep” command transmitted in this step corresponds to the first switching command described in the claims, and this step constitutes a first switching command transmitting means.

On the other hand, in step S155, the control circuit 11, when the number of slots reaches ^{2 Q,} the determination is satisfied and the routine goes to Step S170.

  In step S170, the control circuit 11 determines whether or not the slot number designation value Q set to Qmax in step S110 is zero. If the slot number designation value Q is not 0, the determination is not satisfied and the routine goes to Step S175, where 1 is subtracted from the slot number designation value Q and the routine returns to the previous Step S115. On the other hand, if the slot number designation value Q is 0 in step S170, the determination is satisfied and this flow ends.

  FIG. 8 is a flowchart showing the detailed contents of step S200, which is the communication process by the second antenna B.

  In step S205, the control circuit 11 switches the changeover switch SW to the second antenna B side, and switches to the RFID circuit portions To of all the RFID tags T existing in the second communicable region 22 including the area 2 and the area 3. On the other hand, a “Select” command is transmitted. As a result, only the RFID tag circuit section To whose inventory flag content is “B” is in a state where radio communication can be performed thereafter. Further, in the “select” command, it is specified that the contents of the inventory flag are automatically reversed when the tag ID is read.

  In step S210, the control circuit 11 sets the value of the slot number designation value Q to Qmax.

  In step S215, the control circuit 11 sends tag information as a response to the RFID tag circuit unit To having the content of the inventory flag “B” existing in the second communicable region 22 including the area 2 and the area 3. Send a “Query” command requesting that The “Query” command includes the slot number designation value Qmax set in step S210.

  In step S220, the control circuit 11 initializes a variable n for counting the number of slots to 1.

  In step S225, the control circuit 11 determines whether or not the “RN16” response is normally received as a response signal from the RFID circuit section To during a predetermined reception time corresponding to the identification slot. If the “RN16” response is not normally received, it is considered that there is no RFID tag circuit section To responding in the identification slot, and the determination is not satisfied, and the routine goes to Step S255 described later. On the other hand, if the “RN16” response is normally received, it is assumed that there is a RFID circuit unit To responding in the identification slot, the determination is satisfied, and the routine goes to Step S230.

  In step S230, the control circuit 11 has the content corresponding to the “RN16” response received in step S215 to the RFID circuit part To existing in the second communicable area 22 including the areas 2 and 3. An “Ack” command that permits transmission of tag information is transmitted.

  Note that the RFID circuit section To that has read the tag information by wireless communication with the second antenna B in the area 3 or the area 2 must always be already connected by wireless communication with the first antenna A in the area 1. Since it is read, this flowchart does not include the procedure corresponding to the above-described steps S135 and S140.

  In step S245, the control circuit 11 adds 1 to the value of the tag count, and in step S250, the control circuit 11 acquires time information from the timer unit 14 and stores it in the storage unit 15 as a communication time corresponding to the tag count. .

In step S255, the control circuit 11 determines whether or not the variable n for counting the number of slots is 2 ^Q. If the number of slots does not reach the 2 ^Q proceeds to step S260 the determination is not satisfied.

  In step S260, the control circuit 11 adds 1 to the variable n, and in step S265, the control circuit 11 includes the inventory that exists in the second communicable area 22 including the area 2 and the area 3 in the next identification slot. A “QueryRep” command is transmitted to the RFID circuit unit To whose flag content is “B”. And it returns to previous step S225. Note that the “QueryRep” command transmitted in this step corresponds to the second switching command described in the claims, and this step constitutes a second switching command transmitting means.

On the other hand, in step S255, the control circuit 11, when the number of slots reaches ^{2 Q,} the determination is satisfied and the routine goes to Step S270.

  In step S270, the control circuit 11 determines whether or not the slot number designation value Q set to Qmax in step S210 is zero. If the slot number designation value Q is not 0, the determination is not satisfied and the routine goes to Step S275, where 1 is subtracted from the slot number designation value Q and the routine returns to the previous Step S215. On the other hand, if the slot number specification value Q is 0 in step S270, the determination is satisfied and this flow ends.

  In the above, Step S225 constitutes an approach judging means given in a claim.

  In the reader 100 of the embodiment described above, the first communicable region 21 of the first antenna A and the second communicable region 22 of the second antenna B are formed along the transport path of the transported object C, respectively. Is done. Further, the first antenna A and the second antenna B are switched by the control circuit 11 so as to alternately communicate with each other. Here, the first communicable area 21 of the first antenna A and the second communicable area 22 of the second antenna B partially overlap to form an area 3 that is an overlapping communicable area. For this reason, the RFID circuit portion To that sequentially moves by the conveyance is switched between the signal from the first antenna A and the signal from the second antenna B as described above while moving in the area 3. It becomes possible to respond to both signals.

  Here, in general, the RFID circuit portion To is affected by the performance of the IC chip 150, the resistance of the attachment portion between the tag antenna 151 and the IC chip 150, the error in the attachment position, and the physical properties of the object to be attached. Etc. cause variations in communication sensitivity. For this reason, even if the output of the communication antenna on the reader side is constant, the communicable area is relatively wide for the RFID circuit unit To having high communication sensitivity, and the RFID circuit unit To having low communication sensitivity is used. On the other hand, the communicable area is relatively narrow. That is, the communicable area from the antenna expands and contracts depending on the communication sensitivity of the RFID tag circuit section To.

  The same applies to the case where the two antennas A and B form the area 3 where overlapping communication is possible as in the reader 100 of the present embodiment. The area 3 is relatively wide for the RFID circuit unit To having high communication sensitivity, and the area 3 is relatively narrow for the RFID circuit unit To having low communication sensitivity. In other words, the size of the area 3 that is the overlapping communicable region varies depending on the communication sensitivity of the RFID circuit portion To. However, the change in the size of the area 3 at this time is originally derived from the expansion and contraction of the communicable areas 21 and 22 from the antennas A and B. Therefore, there is a characteristic that the center position of the area 3 when it becomes wide and the center position of the area 3 when it becomes narrow hardly change.

  The present embodiment applies this characteristic, and when the RFID tag circuit unit To provided on the conveyed product C sequentially moves along the conveyance path, the passage timing of the center position of the area 3 of the RFID tag circuit unit To. Determine. As a result, even when the RFID circuit unit To with high communication sensitivity and the RFID tag circuit unit To with low communication sensitivity are mixed and moved along the transport path, the preceding RFID circuit unit To always The detection is performed in order, and the succeeding RFID tag circuit section To is detected in the later order. That is, it is possible to prevent the reader 100 from erroneously detecting the RFID tag circuit unit To in an order different from the order in which it is conveyed. In this way, according to the present embodiment, by detecting the passage timing at the approximate center position of the area 3 of each RFID circuit portion To, it is possible to accurately grasp the transport order of the transported objects C in the transport path. be able to.

  In the present embodiment, in particular, the entry timing of the RFID tag circuit section To to the area 3 is determined, and the exit timing of the RFID tag circuit section To from the area 3 is determined. Then, based on these determination results, intermediate timing between the entry timing and the exit timing is determined, so that the timing at which each RFID circuit section To passes through the center of area 3 can be detected more accurately. .

  In the present embodiment, in particular, the first antenna A and the second antenna B are transported by the belt conveyor BC by a line L1 connecting the axial center position of the first antenna A and the axial center position of the second antenna B. It is arranged so as to be parallel to the moving direction of the RFID circuit part To in the path. With this arrangement, the center position of the area 3 where the communicable areas 21 and 22 of the two antennas A and B overlap is surely made constant regardless of the sensitivity of the RFID tag circuit section To. Can do.

  In the present embodiment, in particular, when tag information is read by wireless communication using the first antenna A, the contents of the inventory flag of the wireless tag circuit unit To are inverted from “A” to “B”, and the second antenna When the tag information is read by wireless communication by B, the contents of the inventory flag of the wireless tag circuit section To are inverted from “B” to “A”. As a result, once the RFID circuit section To communicates with the first antenna A once on the upstream side of the transport path, the RFID circuit unit To no longer communicates with the same first antenna A, and once communicates with the second antenna B on the downstream side of the transport path. After that, communication with the same second antenna B stops. As a result, it is possible to avoid unnecessary communication in areas other than the area 3 that is the overlapping communication possible area as much as possible, and improve communication efficiency.

  The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit and technical idea of the present invention. Hereinafter, such modifications will be described in order.

(1) When expanding the range of the area 3 In the above embodiment, the first antenna A and the second antenna B are arranged so that the line connecting their axial centers is parallel to the moving direction of the RFID circuit portion To. However, in order to expand the range of the area 3, the first antenna A and the second antenna B may be provided to be inclined with respect to each other.

  FIG. 9 is a system configuration diagram illustrating an outline of the reader 100 according to the present modification. As shown in FIG. 9, the first antenna A and the second antenna B are configured such that a line La in the main lobe direction of the first antenna A and a line Lb in the main lobe direction of the second antenna B are in the belt conveyor BC. Are arranged so as to intersect each other on the transport path. The main lobe direction is a direction in which radio wave radiation is maximized when the first antenna A and the second antenna B are directional antennas. With such an arrangement, the size of the area 3 that is the overlapping communicable region 23 where the communicable regions 21 and 22 of the two antennas A and B overlap can be further increased. As a result, since the number of communication timings in the area 3 can be increased, it is possible to improve the determination accuracy of the passage timing at the center position of the area 3 of the RFID tag circuit section To.

(2) When carrying speed control of the belt conveyor In the above embodiment, the carrying speed of the conveyed product C by the belt conveyor BC is constant, but the carrying speed is controlled based on the communication result by the first antenna A and the second antenna B. You may make it do.

  FIG. 10 is a system configuration diagram illustrating an outline of the conveyed product management system LS of the present modification. As shown in FIG. 10, the conveyed product management system LS controls the reader 100, the belt conveyor BC (conveying means), and the conveying speed of the belt conveyor BC, which are the same as those in the above-described embodiment. A transport controller 200. The control circuit 11 of the reader 100 and the transport controller 200 are connected via a network NW so that signals can be transmitted and received, and the transport controller 200 is connected to a drive motor M that drives the belt conveyor BC.

  The control circuit 11 outputs a control signal to the transport controller 200 via the network NW, and controls the transport speed of the belt conveyor BC. In this modification, when the transport speed by the belt conveyor BC is the first transport speed, the time difference of the passage timing at the center position of the area 3 of the two consecutive RFID tag circuit portions To is more than twice the communication time ΔT. Is smaller, the transport order of the transported object C may not be correctly detected as described above. Therefore, the transport speed of the belt conveyor BC is decreased from the first transport speed, and the two RFID circuit units To Is controlled so that the time difference between the passage timings of the two is greater than twice the communication time ΔT.

  FIG. 11 is a flowchart showing the control contents executed by the control circuit 11 of the reader 100. In FIG. 11, the same steps as those in FIG. 6 described above are denoted by the same reference numerals, and description thereof will be omitted as appropriate.

  Steps S10 to S20 are the same as those in FIG. 6 described above, and the control circuit 11 performs initial setting related to wireless communication, and then switches the changeover switch SW to the first antenna A side to perform communication by the first antenna A. In addition to processing, the selector switch SW is switched to the second antenna B side to perform communication processing by the second antenna B. In addition, the conveyance speed of the conveyed product C by the belt conveyor BC here is set to the 1st conveyance speed. In step S20, it is determined whether or not there is an RFID circuit unit To that cannot read the tag information. If there is no RFID circuit unit To that does not respond in area 1 and RFID circuit unit To that does not respond in area 2, the determination is not satisfied and step S25 is not satisfied. Move on.

  In step S25, the control circuit 11 outputs a control signal to the transport controller 200 via the network NW, and controls so that the transport speed of the belt conveyor BC is increased above the first transport speed. Thereafter, the process proceeds to step S50 described later.

  On the other hand, if there is no RFID circuit section To that cannot read the tag information in step S20, the determination is satisfied and the routine goes to step S30. Step S30 is the same as that in FIG. 6 described above, and the control circuit 11 determines whether or not the tag count of the wireless tag circuit unit To determined to exist in step S20 is -1. When the tag count is −1, that is, when the RFID circuit unit To that has become unable to read the tag information is the RFID circuit unit To that has stopped responding in the area 1, the process proceeds to step S25 and the control is performed. The circuit 11 controls the conveyor speed of the belt conveyor BC so as to be higher than the first conveyor speed.

  On the other hand, if the tag count is not -1 in step S30, that is, if the RFID circuit unit To that has become unable to read tag information is the RFID circuit unit To that has stopped responding in the area 2 described above. The process proceeds to step S33.

  In step S <b> 33, the control circuit 11 determines whether or not there are a plurality of RFID tag circuit portions To whose tag counts are not −1, in which tag information cannot be read. If there are a plurality of RFID circuit sections To, that is, there are a plurality of RFID circuit sections To that no longer respond in area 2, the determination is satisfied and the routine goes to Step S35. In this case, the time difference between the passage timings of the center positions of the areas 3 of the two consecutive RFID tag circuit portions is smaller than twice the communication time ΔT, and the transport speed of the belt conveyor BC is considered to be too fast. In Step S35, 11 outputs a control signal to the transport controller 200 via the network NW to control the transport speed of the belt conveyor BC to be lower than the first transport speed. At this time, the conveyance order of the conveyed product C can be reliably detected by reducing the conveyance speed so that the time difference between the passage timings of the two RFID circuit units To is greater than twice the communication time ΔT. Thereafter, the process proceeds to step S40.

  On the other hand, when there is only one RFID tag circuit section To whose tag count is not −1, in which tag information cannot be read in step S33, the determination is not satisfied, and the routine goes to step S40. Subsequent steps S40 and S50 are the same as those in FIG.

  In the above, step S35 constitutes the reduction control means described in the claims, and step S35 and step S25, and step S45 shown in FIG. 12, which will be described later, constitute the transport control means.

  In the modified example described above, the conveyance speed by the belt conveyor BC can be increased in a speed range in which the conveyance order of the conveyed product C can be correctly detected. Therefore, the conveyance efficiency by the belt conveyor BC can be improved while correctly detecting the conveyance order. Can be improved.

  In the above modification, the transport speed is reduced so that the time difference between the passage timings of two consecutive RFID tag circuit portions To is greater than twice the communication time ΔT. Is more than three times the communication time ΔT, conversely, the margin for the detection resolution is too large, and the interval between the conveyed items is unnecessarily vacant, so that the conveying efficiency of the belt conveyor BC decreases. Accordingly, when the transport speed is the second transport speed and the time difference between the passing timings of the two consecutive RFID tag circuit portions To is three times or more of the communication time ΔT, the transport speed of the belt conveyor BC is set to the above. You may make it increase from 2nd conveyance speed.

  FIG. 12 is a flowchart showing the control contents executed by the control circuit 11 of the reader 100. In FIG. 12, the same steps as those in FIGS. 6 and 11 described above are denoted by the same reference numerals, and description thereof will be omitted as appropriate.

  Steps S10 to S33 are the same as those in FIG. In addition, the conveyance speed of the conveyed product C by the belt conveyor BC here is set to the 2nd conveyance speed.

  In step S33, when there are a plurality of RFID circuit units To that cannot read tag information and the tag count is not -1, the determination is satisfied, and the process proceeds to step S35. Then, a control signal is output to the transport controller 200 to control the transport speed of the belt conveyor BC to be lower than the second transport speed. Thereafter, the process proceeds to step S40.

  On the other hand, when there is only one RFID tag circuit section To whose tag count is not −1, in which tag information cannot be read in step S33, the determination is not satisfied, and the routine goes to step S40. Step S40 is the same as that in FIG.

  In step S43, the control circuit 11 determines whether or not the time difference between the passage timings of the two consecutive RFID tag circuit portions To is three times or more the communication time ΔT that is the switching time of the antennas A and B. If the time difference is less than three times the communication time ΔT, the determination is not satisfied and the routine goes to Step S50. On the other hand, when the time difference is three times or more of the communication time ΔT, the determination is satisfied and the routine goes to Step S45.

  In step S45, the control circuit 11 outputs a control signal to the transport controller 200 via the network NW, and controls so that the transport speed of the belt conveyor BC is increased above the second transport speed. Thereafter, the process proceeds to step S50. Step S50 is the same as that in FIG.

  In the above, step S45 constitutes the increase control means described in the claims. Further, as described above, this step S45 and the above-described steps S25 and S35 shown in FIG. 11 constitute a conveyance control means.

  According to the modified example described above, the conveyance speed by the belt conveyor BC is appropriately set such that the time difference between the passage timings of the two RFID circuit sections To is between twice and three times the communication time ΔT. It can be controlled to be within the speed range. Accordingly, it is possible to efficiently detect the conveyance order while suppressing unnecessary margins and unnecessary intervals between the conveyance objects with respect to the detection resolution due to excessive reduction of the conveyance speed described above.

(3) Others In the above embodiment, the switching patterns of the antennas A and B are alternately switched once every time as “A → B → A → B → A...” For example, you may make it switch alternately several times like "A->A->B->B->A->A->B->B-> A ...". In this case, it is possible to improve the determination accuracy in the overlapping communicable region 23 in which communication is unstable by determining that communication is impossible when information cannot be read continuously a plurality of times.

  In the above embodiment, the reader main body 10 of the reader 100 has the timekeeping unit 14 and the storage unit 15. However, the reader 100 does not necessarily need to have these. For example, the timer unit 14 and the storage unit 15 are provided in an external device such as a server capable of transmitting / receiving information to / from the reader 100, and a signal that informs the external device when the reader 100 communicates with the RFID circuit unit To. The communication timing may be stored in the external device.

  In the modification (2) described above, the conveyance speed of the belt conveyor BC is controlled based on the communication results of the first antenna A and the second antenna B. However, the present invention is not limited to this. The communication time ΔT (first time interval) for one antenna A and the communication time ΔT (second time interval) for the second antenna B may be increased or decreased. For example, when the time difference between the passing timings of two consecutive RFID tag circuit parts To is smaller than twice the communication time ΔT, the switching timing of the antennas A and B is advanced to set the communication time ΔT and the first time of the first antenna A. By reducing the communication time ΔT by the two antennas B, the time difference can be made larger than twice the communication time ΔT. As a result, it is possible to correctly detect the transport order of the transported object C without changing the transport speed of the belt conveyor BC.

  In addition, in the above, the arrow shown in FIG. 2 shows an example of a signal flow, and does not limit the signal flow direction. The flowcharts shown in FIG. 6, FIG. 7, FIG. 8 and the like do not limit the present invention to the procedure shown in the above flow, and the addition / deletion or order of the procedures within the scope of the gist and technical idea of the invention. May be changed.

  In addition to those already described above, the methods according to the above-described embodiments and modifications may be used in appropriate combination.

  In addition, although not illustrated one by one, the present invention is implemented with various modifications within a range not departing from the gist thereof.

13 Changeover switch (switching control means)
14 Timekeeping (Timekeeping means)
15 Storage unit (storage means)
21 First communicable area (first communicable range)
22 Second communicable area (second communicable range)
23 Overlapping communication possible area (overlapping communication range)
100 reader (wireless tag reader)
150 IC circuit unit 151 Tag antenna 155 Memory unit (storage unit)
A First antenna (first communication antenna)
B Second antenna (second communication antenna)
BC belt conveyor (conveyance means)
C Conveyed object L line LS Conveyed object management system IF Inventory flag (switching identifier)
To wireless tag circuit

Claims (9)

A plurality of wireless devices each provided with a tag antenna for transmitting / receiving information to / from an IC circuit unit provided with a storage unit for storing information, provided on each of a plurality of items to be sequentially transferred in one direction along a predetermined transfer path A wireless tag reader for sequentially detecting tag circuit portions,
A first communication antenna that forms a first communicable range in a predetermined portion of the transport path;
A second communication antenna that forms a second communicable range that partially overlaps the first communicable range at a portion downstream of the predetermined portion of the transport path in the transport direction;
Switching control means for performing switching control between the first communication antenna and the second communication antenna so that the first communication antenna and the second communication antenna perform communication alternately;
Based on the presence / absence of a response signal from the wireless tag circuit unit received by the first communication antenna and the second communication antenna that are switch-controlled by control of the switch control means, the moving along the transport path A wireless tag reading device comprising: a wireless tag circuit unit including passage determination means for determining a passage time of an overlapping communication range in which the first communicable range and the second communicable range overlap. Clocking means for timing the time at which the first communication antenna and the second communication antenna receive a response signal from the RFID circuit unit;
Storage means for storing the time measured by the time measuring means as communication time,
The passage determination means includes
2. The wireless tag reader according to claim 1, wherein the passage time of the overlapping communication range is determined using the communication time stored in the storage means. The passage determination means includes
Among the communication times stored in the storage means, the second communication antenna receives the response signal from a state in which the response signal from the RFID tag circuit unit is not received. An entry determination means for determining an entry time into the communication range;
Since the response signal is not received from the state in which the response signal is received from the wireless tag circuit unit in the first communication antenna from the communication time stored in the storage unit, the overlapping communication range Exit determination means for determining the exit time from
The wireless tag reader according to claim 1, further comprising an intermediate determination unit that determines an intermediate time between the entry time and the exit time. The first communication antenna and the second communication antenna are:
The line connecting the axial center position of the first communication antenna and the axial center position of the second communication antenna is arranged so as to be parallel to the moving direction of the RFID circuit part in the transport path. The wireless tag reader according to any one of claims 1 to 3, wherein The first communication antenna and the second communication antenna are:
5. The main lobe direction line of the first communication antenna and the main lobe direction line of the second communication antenna are arranged so as to intersect on the transport path. Wireless tag reader. The wireless that stores in the storage unit a switching identifier that can be switched between a first state for transmitting / receiving information to / from the first communication antenna and a second state for transmitting / receiving information to / from the second communication antenna. A first switching command transmitting means for transmitting a first switching command for switching from the first state to the second state to the tag circuit unit using the first communication antenna;
The wireless tag circuit unit further comprises a second switching command transmission means for transmitting a second switching command for switching from the second state to the first state using the second communication antenna. The wireless tag reader according to any one of claims 1 to 5. A plurality of transported objects each provided with an IC circuit unit having a storage unit for storing information and a wireless tag circuit unit having a tag antenna for transmitting and receiving information are sequentially transported in one direction along a predetermined transport path. Conveying means;
A transport control means for controlling the transport speed of the transport means;
A first communication antenna that forms a first communicable range in a predetermined part of the transport path, and a part of the transport path downstream of the predetermined part in the transport direction so as to partially overlap the first communicable range Assigning a first time segment to the communication of the first communication antenna and a second communication antenna forming a second communicable range, and assigning a second time segment to the communication of the second communication antenna, Switching control means for performing switching control of the first communication antenna and the second communication antenna so that the first communication antenna and the second communication antenna perform communication alternately according to the time segment and the second time segment; Based on the presence or absence of a response signal from the wireless tag circuit unit received by the first communication antenna and the second communication antenna that are controlled to be switched by the control of the switching control means, A wireless tag reader having passage determination means for determining a passage time of an overlapping communication range in which the first communicable range and the second communicable range of the wireless tag circuit unit moving along the transmission path overlap; Conveyance management system having
The transport control means includes
When the transport speed of the transport means is the first transport speed, the passage time of the overlapping communication range of the one RFID tag circuit unit determined by the passage determination means and the passage determination means When the time difference with the passing time of the overlapping communication range of the RFID tag circuit unit different from the one RFID tag circuit unit is smaller than the sum of the first time segment and the second time segment, A transported object management system, comprising: a decrease control unit that controls the transporting speed of the transporting unit to be lower than the first transporting speed. The transport control means includes
If the time difference when the transport speed of the transport means is the second transport speed is three times or more of the first time segment, or three times or more of the second time segment, the transport The transported object management system according to claim 7, further comprising an increase control unit configured to control the transport speed of the means so as to be higher than the second transport speed. A plurality of transported objects each provided with an IC circuit unit having a storage unit for storing information and a wireless tag circuit unit having a tag antenna for transmitting and receiving information are sequentially transported in one direction along a predetermined transport path. Conveying means;
A transport control means for controlling the transport speed of the transport means;
A first communication antenna that forms a first communicable range in a predetermined part of the transport path, and a part of the transport path downstream of the predetermined part in the transport direction so as to partially overlap the first communicable range Assigning a first time segment to the communication of the first communication antenna and a second communication antenna forming a second communicable range, and assigning a second time segment to the communication of the second communication antenna, Switching control means for performing switching control of the first communication antenna and the second communication antenna so that the first communication antenna and the second communication antenna perform communication alternately according to the time segment and the second time segment; Based on the presence or absence of a response signal from the wireless tag circuit unit received by the first communication antenna and the second communication antenna that are controlled to be switched by the control of the switching control means, A wireless tag reader having passage determination means for determining a passage time of an overlapping communication range in which the first communicable range and the second communicable range of the wireless tag circuit unit moving along the transmission path overlap; Conveyance management system having
The switching control means includes
While increasing / decreasing the first time segment and the second time segment, the first communication antenna and the second communication antenna perform communication alternately according to the increased first time segment and the second time segment, A transported object management system that performs switching control between the first communication antenna and the second communication antenna.

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