JP2008244675A - Wireless communication system, antenna switching control method in the system and control program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reliably prevent radio wave interference, while suppressing the cost. <P>SOLUTION: When a carriage A moves along the transport direction and enters a detection area of position detection portions 7a and 7b, a main control portion 26 controls to turn on only single antenna 3a (3b, 3c, 3d) corresponding to a passage section of the carriage A and turn off antennas 4a, 4b, 4c, and 4d. If the carriage A passes through the detection area of the position detection portions 7a and 7b and enters an intermediate area between the detection area of the position detection portions 7a and 7b and a detection area of position detection portions 8a and 8b, the main control portion 26 controls to turn off all the antennas 3a, 3b, .... <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a radio communication system, an antenna switching control method and a control program in the system, and, for example, when an article such as a baggage is carried on a carriage or the like, the article is provided via an antenna installed on a conveyance path. A wireless communication system for reading article information including identification information stored in a storage unit of an RFID (Radio Frequency Identification) tag (hereinafter also referred to as an RF tag) attached to or writing article information in the storage unit The present invention relates to an antenna switching control method and a control program in the system.

2. Description of the Related Art Conventionally, for example, in an article sorting system that sorts articles, a barcode reader that reads barcode tags attached to articles to be conveyed has been used.
However, when using a bar code tag, the optical area of the bar code tag must be increased in order to increase the amount of information, and the bar code tag is liable to be damaged during the transportation of articles, and is affected by dirt. There is a problem that it is easy to receive and can only read information.

  For this reason, RFID tags have been frequently used recently. RFID tags are broadly classified into active RFID tags having a power source therein and passive RFID tags that obtain power from an external electric field or magnetic field.

  In a wireless communication system using an RFID tag, a passive RFID tag is mainly used in order to reduce costs. The passive RFID tag uses electromagnetic energy supplied from an external reader / writer to drive a semiconductor circuit and respond to a request from the reader / writer.

  For this reason, the passive RFID tag can be used only in the communicable area of the reader / writer that generates an electric field and a magnetic field having a predetermined strength for driving the semiconductor circuit. Therefore, in this wireless communication system, the RFID tag attached to the article being conveyed can be used within the time that is present in the fixed communicable area.

In such a wireless communication system using an RFID tag, in a gate provided on a conveyance path (for example, a store passage or a factory production line) through which articles pass within the communicable area, above the conveyance path. The reader / writer performs collective transmission / reception of radio waves to / from a plurality of RFID tags via the antenna to acquire or give article information.
However, when the transfer area is wide at the gate, communication with the RFID tag cannot be reliably performed with one antenna depending on the passage position of the article.

By connecting multiple antennas to one reader / writer and increasing the number of antennas, it is possible to cope with the size of the transport area. However, since transmission and reception of radio waves using antennas is performed in a time-sharing manner, it takes a short time. It was difficult to read.
That is, ((total transmission / reception time of one antenna) ≈ (passage time of article) / (total number of antennas)), so that a plurality of antennas are installed so as to be compatible with all transport areas, and radio waves are simultaneously transmitted. Radiating, the total transmission / reception time of each antenna is shortened, and the reading rate of article information by one antenna is lowered. For example, even when an appropriate antenna is used that allows the article to pass nearby. Similarly, the reading rate is lowered.

For this reason, a plurality of reader / writers may be installed and one antenna may be connected to each reader / writer. However, radio waves are radiated from the plurality of antennas at the same time, so that radio wave interference occurs, and article information The reading rate will be reduced. In addition, the installation of a plurality of reader / writers increases the cost.
For this reason, a technique has been proposed in which a plurality of antennas are connected to one reader / writer (transceiver) and the antennas are switched (see, for example, Patent Document 1, Patent Document 2, and the like).

In a mobile phone or the like having a communication function with an RFID tag, a technique is used in which a plurality of antennas are connected to a single reader / writer, and the antennas are switched according to the state of the mobile phone (moving direction and inclination angle). Has been proposed (for example, see Patent Document 3).
In addition, a technique has been proposed in which a plurality of antennas connected to a reader / writer are arranged around a turntable on which a large number of RFID tags are placed, and the antennas are switched according to the rotation of the turntable (for example, patents). Reference 4 etc.).
JP 2002-356227 A JP 2006-109131 A JP 2006-148472 A JP 2005-004532 A

The problem to be solved is that the conventional technique still cannot reliably prevent radio wave interference.
That is, when the above-described conventional technology is applied to communication with an RFID tag attached to an article, for example, when another gate is arranged nearby, it is different even if a specific antenna is selected. There is a possibility of causing radio wave interference with the antenna of the gate.

For example, when the prior art described in Patent Document 3 is applied to communication with an RFID tag attached to an article, the antenna is switched according to the state of the device itself, so that it matches the external environment (RFID tag state). Therefore, it does not have a function of switching antennas.
For this reason, it is difficult to apply to a wireless communication system in which the antenna needs to be switched according to the position of the RFID tag passing through the gate.

  The present invention has been made in view of the above-described circumstances, and provides a radio communication system capable of reliably preventing radio wave interference while suppressing cost, an antenna switching control method, and a control program in the system. It is aimed.

In order to solve the above-mentioned problem, the invention according to claim 1 is provided between a wireless tag attached to an article moving on a conveyance path or packaging of the article and having a storage means for storing article information relating to the article. The present invention relates to a wireless communication system for receiving and / or transmitting the article information via radio, and receiving the article information via a plurality of antennas installed along the conveyance path and the predetermined antenna. Or / and based on the position detection information output from the position detection means, the position detection means for detecting the position of the article to which the wireless tag or the wireless tag is attached, Based on the position detection information, the antenna selection means for selecting the antenna to be used for communication between the article information transfer means and the wireless tag among the plurality of antennas, When the wireless tag or the article to which the wireless tag is attached is detected, the article information transfer means is controlled to radiate an electromagnetic wave for communication with the wireless tag from the selected antenna. It is characterized by comprising a control means.
Here, the article information exchanging means means a broad concept including article information acquisition only, supply only, and acquisition / supply combined use. Moreover, an article shall mean the wide concept containing a member, an apparatus, etc.

  The invention according to claim 2 relates to the wireless communication system according to claim 1, wherein the control means, when the wireless tag or the article is not detected based on the position detection information, The article information transmitting / receiving means is controlled so as not to radiate electromagnetic waves for the communication of the plurality of antennas from the plurality of antennas.

  According to a third aspect of the present invention, there is provided the wireless communication system according to the first or second aspect, further comprising an antenna switching means for switching and connecting the antennas to the article information transmitting / receiving means. Is characterized by controlling the article information transmitting / receiving means to cause the antenna switching means to switch to the antenna selected by the antenna selecting means.

  According to a fourth aspect of the present invention, there is provided the wireless communication system according to the first, second, or third aspect, wherein the antenna selecting means selects a single antenna among the plurality of antennas. Yes.

  The invention according to claim 5 relates to the radio communication system according to any one of claims 1 to 4, wherein the antenna selection means is the radio tag or the radio tag among the plurality of antennas. The antenna closest to the movement path of the worn article is selected.

  A sixth aspect of the present invention relates to the wireless communication system according to any one of the first to fifth aspects, wherein the transport path is divided into a plurality of sections, and the antennas correspond to the sections. It is attached, It is arranged so that the above-mentioned conveyance way may be crossed above the above-mentioned conveyance way.

  The invention according to claim 7 relates to the wireless communication system according to claim 6, wherein a first wireless tag and a second wireless tag are attached to a front side and a rear side of the article, respectively. The plurality of antennas are arranged in two rows for the first antenna group and the second antenna group, and the antennas of the first antenna group are used for communication with the first wireless tag. The antennas of the second antenna group are used for communication with the second wireless tag.

  The invention according to claim 8 relates to the wireless communication system according to any one of claims 1 to 7, wherein a plurality of the articles are loaded on the transport body along the transport path and moved to the position. The detection means includes at least a pair of position sensors that detect distances to the conveyance bodies arranged on both sides of the conveyance path, and the antenna selection means is based on distance information output from the pair of position sensors. Detecting the position of the transport path, the control means calculates the width of the transport body based on the distance information output from the pair of position sensors, the width of the transport body is less than a predetermined value Sometimes, it is determined that the transport body is detected, and when the width of the transport body exceeds a predetermined value, it is determined that the transport body is not detected.

  Further, the invention described in claim 9 is the article information between the wireless tag which is attached to the article moving on the conveyance path or the packaging of the article and has storage means for storing the article information relating to the article. According to an antenna switching control method in a wireless communication system for receiving or / and transmitting via wireless, a position detecting step for detecting a position of the wireless tag or the article to which the wireless tag is attached; Based on the position detection information obtained in the position detection step, communication between the wireless tag and the article information exchanging means for receiving or / and transmitting the article information among the plurality of antennas installed along the conveyance path The antenna selection step for selecting the antenna to be used for the detection, and the wireless tag or the article to which the wireless tag is attached is detected based on the position detection information. Occasionally, it is characterized in that a control step of controlling the article information transfer means so as to radiate electromagnetic waves from selected the above antenna for communicating with the wireless tag.

  The invention according to claim 10 relates to the antenna switching control method in the wireless communication system according to claim 9, wherein, in the control step, when the wireless tag or the article is not detected based on the position detection information. The article information transmitting / receiving means is controlled so that electromagnetic waves for communication with the wireless tag are not radiated from the plurality of antennas.

  The invention described in claim 11 relates to the antenna switching control method in the wireless communication system according to claim 9 or 10, wherein the article information transfer means includes antenna switching means for switching and connecting the antennas. In the control step, the article information exchange means is controlled to cause the antenna switching means to switch to the antenna selected in the antenna selection step.

  A twelfth aspect of the present invention relates to an antenna switching control method in a wireless communication system according to the ninth, tenth, or eleventh aspects, wherein, in the antenna selection step, a single antenna among the plurality of antennas is selected. It is characterized by doing.

  The invention described in claim 13 relates to the antenna switching control method in the wireless communication system according to any one of claims 9 to 12, wherein in the antenna selection step, the wireless tag or the antenna among the plurality of antennas is selected. The antenna closest to the movement path of the article to which the wireless tag is attached is selected.

  The invention according to claim 14 relates to the antenna switching control method in the wireless communication system according to any one of claims 9 to 13, wherein the transport path is divided into a plurality of sections, and each antenna is It is characterized by being arranged so as to cross the conveyance path above the conveyance path in association with the respective sections.

  The invention according to claim 15 relates to the antenna switching control method in the wireless communication system according to claim 14, wherein the first wireless tag and the second wireless tag are respectively provided on the front side and the rear side of the article. The plurality of antennas are arranged in two rows for the first antenna group and the second antenna group, and the antennas of the first antenna group communicate with the first wireless tag. The antenna of the second antenna group is used for communication with the second wireless tag.

  According to a sixteenth aspect of the present invention, there is provided the antenna switching control method in the wireless communication system according to any one of the ninth to fifteenth aspects, wherein a plurality of the articles are stacked on a conveyance body along the conveyance path. In the position detection step, at least a pair of position sensors that detect distances to the transport bodies arranged on both sides of the transport path are used, and in the antenna selection step, the position sensors output from the pair of position sensors. Based on the distance information, the position of the transport path is detected. In the control step, the width of the transport body is calculated based on the distance information output from the pair of position sensors, and the width of the transport body is calculated. It is determined that the transport body is detected when it is equal to or less than a predetermined value, and the transport body is determined not to be detected when the width of the transport body exceeds a predetermined value. To have.

  Further, the invention according to claim 17 provides the article information to or from a wireless tag attached to an article moving on the conveyance path or packaging of the article and having a storage means for storing article information relating to the article. The present invention relates to a control program for causing a computer to execute an antenna switching control method in a wireless communication system for receiving or / and transmitting via wireless, and detecting the position of the wireless tag or the article to which the wireless tag is attached. Position detection step for performing and, based on the position detection information obtained in the position detection step, among the plurality of antennas installed along the conveyance path, article information for receiving and / or transmitting the article information An antenna selection step for selecting the antenna to be used for communication between the transfer means and the wireless tag; and the wireless tag based on the position detection information. Or a control step of controlling the article information transmitting / receiving means so that an electromagnetic wave for communication with the wireless tag is radiated from the selected antenna when the article to which the wireless tag is attached is detected. It is characterized by having a computer execute.

  According to the configuration of the present invention, the antenna selection unit selects an antenna to be used for communication between the article information transfer unit and the wireless tag among the plurality of antennas based on the position detection information output from the position detection unit. The control means causes the electromagnetic wave for communication with the wireless tag to be radiated from the selected antenna when the wireless tag or the article with the wireless tag attached is detected based on the position detection information. Since the information transmission / reception means is controlled, it is possible to reliably prevent radio wave interference while suppressing costs.

  Based on the position detection information output from the position detection means, the antenna selection means selects an antenna to be used for communication between the article information transfer means and the wireless tag, and the control means determines the position detection information. By controlling the article information transmitting / receiving means to radiate electromagnetic waves for communication with the wireless tag from the selected antenna when the wireless tag or the article with the wireless tag attached is detected based on The purpose of reliably preventing radio wave interference while reducing costs was realized.

  1 and 2 are explanatory diagrams for explaining the configuration of an RFID communication system according to an embodiment of the present invention, FIG. 3 is a block diagram showing the configuration of the RFID communication system, and FIG. 4 is the RFID communication. FIG. 5 is a block diagram showing the configuration of the reader / writer of the RFID communication system, FIG. 6 is a block diagram showing the configuration of the controller of the RFID communication system, and FIG. FIG. 8 and FIG. 9 are explanatory diagrams for explaining the operation of the RFID communication system.

As shown in FIG. 1 to FIG. 3, the RFID communication system 1 of this example, for example, takes an article B that is three-dimensionally loaded and transported on a carriage A along a predetermined transport path in a factory production line. For example, a passive RFID tag 2a (2b) that is worn and stores predetermined article information, and antennas 3a (3b, 3c) that are arranged so as to cross the conveyance path and are arranged in two rows above the conveyance path. 3d) or a tag data reader / writer (hereinafter also simply referred to as a reader / writer) 5 for transmitting / receiving article information via the antenna 4a (4b, 4c, 4d) and the antennas 3a, 3b, 3c, Antenna switching device 6 for switching to a single antenna 3a (3b, 3c, 3d) of 3d or a single antenna 4a (4b, 4c, 4d) of antennas 4a, 4b, 4c, 4d The RFID tags 2a (2b) based on the position information of the position detectors 7a, 7b, 8a, 8b for detecting the passing position of the carriage A and the position detectors 7a, 7b (8a, 8b), for example. The controller 3 selects the antenna 3a (3b, 3c, 3d) or the antenna 4 (4b, 4c, 4d) to be communicated (the highest communication efficiency) and controls the antenna switching device 6 via the reader / writer 5 The controller 9 is connected to the server 11 via, for example, a network.
In the RFID communication system 1 of this example, the reader / writer 5 and the RFID tag 2a (2b) communicate with each other by, for example, an electromagnetic induction method using radio waves of 13.56 MHz.

In this example, a predetermined region R at a gate on a conveyance path (for example, a store passage or a factory production line) is divided into four sections R ₁ , R ₂ ,. In this region R, the carriage A moves along one of the sections R ₁ (R ₂ , R ₃ , R ₄ ).
Here, the width w ₁ of the compartments _{R 1 (R 2, R 3} , R 4) (w 2, w 3, w 4) is set equal _{to, (w 1 = w 2 =} w 3 = w 4 = 2w / N) (see FIG. 8). Here, w is the width of the region R, and n is the total number of antennas.

  The region R is provided with a gate for transmitting / receiving (giving and acquiring) the article information to and from the RFID tag 2a (2b) attached to the article B loaded on the passing carriage A, and the entrance of the gate The antennas 3a, 3b, 3c, 3d on the entrance side and the antennas 4a, 4b on the exit side using the columns 12a, 12b, 13a, 13b above the transport path, respectively, in one row on the side and on the exit side , 4c, 4d are arranged.

The antennas 3a, 3b, 3c, and 3d emit electromagnetic waves as direct waves toward the RFID tag 2a, and the antennas 4a, 4b, 4c, and 4d transmit electromagnetic waves as direct waves toward the RFID tag 2b. In order to radiate, they are arranged at a predetermined angle with respect to the horizontal plane, obliquely below the rear and obliquely below the front, respectively.
The antennas 3a, 3b, 3c, 3d, 4a, 4b, 4c, and 4d are connected to the antenna switching device 6, respectively.

Further, the antennas 3a, 3b, 3c, 3d (4a, 4b, 4c, 4d) have the respective center positions (y = s ₁ , s ₂ , s ₃ , s ₄ ) of the radiation planes, and the sections R ₁ , R ₂ , R ₃ and R ₄ are arranged so as to substantially coincide with the center position (see FIG. 8).
That is, the antenna 3a (3b, 3c, 3d) (4a (4b, 4c, 4d)) of the i-th section counted from the left end has a distance y from the left end (position of the position detection unit 7a) of the transport path. Based on the width w of the transport path and the total number n of antennas, the antenna is arranged as given by equation (1).

(Equation 1)
y = (2i-1) w / n (1)

Here, (1 ≦ i ≦ (n / 2)). In this example, (n = 1, 2, 3, 4), where (n = 8). Therefore, (s ₁ = w / 8, s ₂ = 3 w / 8, s ₃ = 5 w / 8, s ₄ = 7 w / 8).

Each antenna 3a (3b, 3c, 3d) and each antenna 4a (4b, 4c, 4d) are arranged corresponding to each section R ₁ (R ₂ , R ₃ , R ₄ ), and the corresponding section R _{1 (R 2, R 3,} R 4) RFID tag 2a which is attached to the stacked articles B to carriage a to move and 2b, the transmission and reception of radio waves performed. Thereby, regardless of which section R ₁ (R ₂ , R ₃ , R ₄ ) the carriage A moves, it enters the electromagnetic wave radiation region.
For example, the antenna 3a (3b, 3c, 3d) radiates a radio wave toward the RFID tag 2a mounted on the front side of the article B that is loaded on the carriage A and approaches the antenna 3a (4b, 4c, 3d). 4d) radiates radio waves toward the RFID tag 2b attached to the rear side of the article B moving away.

In this example, as shown in FIG. 2, RFID tags 2a and 2b are attached to the front side and the rear side of the article B along the traveling direction of the carriage A, respectively.
The RFID tag 2a (2b) is a non-contact type data carrier. As shown in FIG. 4, the RFID tag 2a (2b) is composed of a CPU (Central Processing Unit) and the like. A storage unit 16 for storing various information such as article information including corresponding identification information, for example, a coil-type antenna 17, a power receiving unit 18 including a rectifier circuit, and a wireless communication unit 19 including a modem circuit. And has.

The article information stored in the storage unit 16 includes, for example, individual identification information, article type information, delivery destination information, and the like, and is used in the process of conveying and sorting the article B.
The RFID tag 2b has an antenna surface facing the direction between the transport direction (x-axis direction) on the horizontal plane and the vertical direction (z-axis) along the vertical plane. The tag surface is attached to the article B along the vertical plane so as to face the direction between the conveying direction on the horizontal plane (-x axis direction) and the vertical direction (z axis). The

  The reader / writer 5 is connected to the antenna switching device 6 and the controller 9, and supplies power and an article information request signal or article information to the RFID tag 2a (2b). As shown in FIG. A control unit 21 that controls each part of the reader / writer main body, a semiconductor memory, a storage unit 22 that stores programs executed by the control unit 21 and various information, a coil-type antenna 23, and a modem. And a wireless communication unit 24 including a circuit.

  The reader / writer 5 is a detection area of the position detectors 7a and 7b (8a and 8b), and within the communicable area including directly below the antennas 3a, 3b, 3c and 3d (4a, 4b, 4c and 4d). Using the switching device 6, electromagnetic waves are radiated from the selected antenna 3a (3b, 3c, 3d) or antenna 4a (4b, 4c, 4d) to communicate with the RFID tag 2a (2b).

The antenna switching device 6 receives instructions from the controller 9 via the reader / writer 5, and appropriately switches the antennas 3a, 3b, 3c, 3d and the antennas 4a, 4b, 4c, 4d.
The position detection units 7a and 7b (8a and 8b) have a photoelectric sensor including a light emitting unit and a light receiving unit. The position detectors 7a and 7b are arranged at both ends of the transfer path on the gate entrance side, and the position detectors 8a and 8b are arranged at both ends of the transfer path on the gate exit side.

  As shown in FIG. 6, the controller 9 includes a main control unit 26 having a CPU (central processing unit) and the like, and a storage unit 27 for storing a processing program executed by the main control unit 26, various data, and the like. And an information processing apparatus such as a computer provided with an operation unit 28 and a display unit 29.

  The main control unit 26 executes various processing programs stored in the storage unit 27, controls each component using various registers and flags secured in the storage unit 27, and acquires a cart position information acquisition process and a cart width. A calculation process, a cart detection process, a passing line identification process, an antenna switching control process, an article information acquisition process, an article information awarding process, and the like are executed.

The main control unit 26 acquires position information (distance information) of the carriage A from the position detection units 7a and 7b (8a and 8b) in the carriage position information acquisition process.
For example, when the carriage A moves along the conveyance path and enters the detection area of the position detection units 7a and 7b, the main control unit 26 determines the distance y ₁ to the carriage A from the position detection units 7a and 7b, A detection signal corresponding to y ₂ is received from the position detection units 7a and 7b and stored in the storage unit 27 (see FIG. 8).

When the carriage A enters the detection area of the position detection units 8a and 8b, the main control unit 26 outputs detection signals corresponding to the distances y ₁ and y ₂ from the position detection units 8a and 8b to the carriage A. , Received from the position detection units 8 a and 8 b and stored in the storage unit 27.
The main control unit 26 is a carriage width calculation processing, the position information of the carriage A (distance y _1, y _2), based on the width w of the transport path, by the equation (2), the width d of the carriage (A) Is calculated.

(Equation 2)
d = w− (y ₁ + y ₂ ) (2)

Further, the main control unit 26 determines whether or not the calculated width d of the carriage A is smaller than the width w of the conveyance path (d <w) in the carriage detection process.
That is, when (d <w), the main control unit 26 determines that the carriage A exists within the detection area of the position detection units 7a and 7b (8a and 8b), and (d ≧ w) At this time, it is determined that the carriage A does not exist in the detection area of the position detection units 7a and 7b (8a and 8b). That is, the main control unit 26 detects the trolley at (d <w) and does not detect the trolley at (d ≧ w).

Further, the main control unit 26, in the passing line specifying process, at the time of detecting the carriage, based on the width d of the carriage A, the width w of the conveyance path, and the total number n of antennas, in the region R according to the equation (3) The section R ₁ (R ₂ , R ₃ , R ₄ ) where the carriage A is moving is identified as the number (i-th) section counted from the left end.

(Equation 3)
(2w (i−1) / n) <(y ₁ + d / 2) <(2wi / n) (3)

The main control unit 26 obtains a value of i that satisfies Equation (3). The passing section of the carriage A is the section R ₁ when (i = 1), the section R ₂ when (i = 2), and the section R ₃ (i = 4) when (i = 3). when a compartment R _4.
Here, the corresponding antennas are the antennas 3a, 3b, 3c, and 3d, respectively, when the carriage A is present in the detection area of the position detectors 7a and 7b, i = 1, 2, 3, and 4, respectively. When A exists in the detection area of the position detection units 8a and 8b, i = 1, 2, 3, and 4, and antennas 4a, 4b, 4c, and 4d, respectively.

Further, the main control unit 26 turns on only the selected antenna 3a (3b, 3c, 3d) or antenna 4a (4b, 4c, 4d) (with respect to the reader / writer 5) at the time of detecting the carriage in the antenna switching control process. Electromagnetic waves are radiated from this antenna as a connected state), and when the carriage is not detected, all the antennas 3a, 3b, 3c, 3d, 4a, 4b, 4c, 4d are turned off (not connected to the reader / writer 5). An antenna selection control signal is sent to the reader / writer 5 so as to stop the emission of electromagnetic waves, and the antenna switching device 6 is controlled via the reader / writer 5.
Thus, the main control unit 26 turns on only the specific single antenna 3a (3b, 3c, 3d) or the antenna 4a (4b, 4c, 4d) that is determined to have the highest communication efficiency, and performs other communication. Unnecessary antennas are turned off, and radio waves are radiated from specific antennas.

For example, when the carriage A moves in the conveyance direction and enters the detection area of the position detectors 7a and 7b, the main control unit 26 detects a single antenna 3a (3b) corresponding to the passing section of the carriage A. , 3c, 3d) are turned on and the antennas 4a, 4b, 4c, 4d are turned off.
In addition, the main control unit 26 moves the carriage A along the transport direction, moves out of the detection area of the position detection units 7a and 7b, detects the detection areas of the position detection units 7a and 7b, and the position detection unit 8a. , 8b, the antennas 3a, 3b, 3c, 3d and the antennas 4a, 4b, 4c, 4d are controlled to be turned off.

In addition, the main control unit 26 moves the carriage A from the intermediate region between the detection regions of the position detection units 7a and 7b and the detection regions of the position detection units 8a and 8b as the carriage A moves along the conveyance direction. When entering the detection area of the detectors 8a, 8b, only the single antenna 4a (4b, 4c, 4d) corresponding to the passing section of the carriage A is turned on, and the antennas 3a, 3b, 3c, 3d are turned off. To control.
Further, the main control unit 26 moves all the antennas 3 a, 3 b, 3 c, 3 d, 4 a, 4 b when the carriage A moves in the transport direction and is pulled out of the detection area of the position detection units 8 a, 8 b. , 4c, 4d are controlled to be turned off.

Further, the main control unit 26 controls the reader / writer 5 when detecting a carriage in the article information acquisition process, and via the predetermined antenna 3a (3b, 3c, 3d) or antenna 4a (4b, 4c, 4d). Then, radio waves (power and article information request signal) are transmitted to the RFID tag 2a (2b), and the antenna 3a (3b, 3c, 3d) or the antenna 4a (4b, 4c, 4d) is transmitted from the RFID tag 2a (2b). And article information is acquired via the reader / writer 5.
Based on this article information, the main control unit 26 performs, for example, switching control of the conveyance path of the article B for each delivery destination, pickup of a specific article B, and the like.
In addition, the main control unit 26 transmits the acquired article information to the server 11.
Further, the main control unit 26 controls the reader / writer 5 and detects the carriage through the predetermined antenna 3a (3b, 3c, 3d) or the antenna 4a (4b, 4c, 4d) in the article information giving process. Then, radio waves (power and article information) are transmitted to the RFID tag 2a (2b).

  The storage unit 27 includes an internal storage device and an external storage device. The storage unit information acquisition processing program executed by the control unit, the vehicle width calculation processing program, the vehicle detection processing program, the passing line identification processing program, and the antenna switching control. It has a program storage area in which various processing programs such as a processing program, an article information acquisition processing program, and an article information awarding processing program are stored, and an information storage area in which various setting information is stored.

The information storage area stores setting information such as the width w of the conveyance path (passage or production line), the total number n of antennas, and the number of columns.
The internal storage device includes a semiconductor memory such as a ROM or a RAM. Further, the external storage device includes an FD driver to which an FD (flexible disk) is mounted, an HD driver to which an HD (hard disk) is mounted, an MO disk driver to which an MO (magneto-optical) disk is mounted, or a CD ( Compact discs) -ROM, CD-R (Recordable), CD-RW (ReWritable), DVD (Digital Video Disc) -ROM, DVD-R, DVD-RW, etc. Become.

The operation unit 28 includes a keyboard and a mouse. The display unit 29 includes a CRT display, a liquid crystal display, a plasma display, or the like.
The acquired article information is sent from the controller 9 to the server 11, and the server 11 collects the article information, stores it in a database, and stores it. The stored data is used, for example, for store article management and factory production management.

Next, the operation of the RFID communication system 1 configured as described above will be described with reference to FIGS.
First, an outline of the operation of the main control unit 26 of the controller 9 will be described.
The main control unit 26 acquires position information (distance information) of the carriage A (step SA11 (FIG. 7)).
Next, the main control unit 26 calculates the width of the carriage A based on the acquired position information of the carriage A (step SA12).

Next, the main control unit 26 determines whether or not there is a carriage within the detection range (step SA13). If it is determined that there is a carriage, the process proceeds to step SA14. If it is determined that there is no carriage, step SA15 is performed. Proceed to
In step SA14, the main control unit 26 identifies the passing line of the carriage A, and in step SA16, only the corresponding single antenna 3a (3b, 3c, 3d) or antenna 4a (4b, 4c, 4d) is turned on. Thus, the antenna switching device 6 is controlled via the reader / writer 5, and the process proceeds to Step SA17.

In step SA15, the main control unit 26 controls the antenna switching device 6 via the reader / writer 5 so as to turn off all the antennas 3a, 3b, 3c, 3d and the antennas 4a, 4b, 4c, 4d, Proceed to step SA17.
In step SA17, the main control unit 26 determines whether or not there has been a stop operation from the operation unit 28. If there is a stop operation, the main control unit 26 ends the process, and if there is no stop operation, returns to step SA11. The processes of SA11 to step SA16 are repeatedly executed.

Next, the operation of the RFID communication system 1 will be described in detail.
As shown in FIG. 8, for example, the carriage A moves along the transport direction and enters the detection area of the position detection units 7a and 7b, and the position detection units 7a and 7b receive the position information (distance information) of the carriage A. ) Is output, the main control unit 26 acquires the position information of the carriage A from the position detection units 7a and 7b.
That is, the main control unit 26 receives detection signals corresponding to the distances y ₁ and y ₂ from the position detection units 7a and 7b to the carriage A from the position detection units 7a and 7b, and stores them in the storage unit 27 ( (See FIG. 8).

The main control unit 26 is a carriage width calculation processing, the position information of the carriage A (distance y _1, y _2), based on the width w of the transport path, by the equation (2), the width of the carriage (A) d is calculated (see FIG. 9).
Next, the main control unit 26 determines whether or not the calculated width d of the carriage A is smaller than the width w of the conveyance path (d <w).

  That is, the main control unit 26 determines that the carriage A exists in the detection area of the position detection units 7a and 7b when (d <w), and the carriage A when (d ≧ w). However, it is determined that it does not exist in the detection area of the position detection units 7a and 7b. That is, the main control unit 26 determines that the cart is detected when (d <w) and that the cart is not detected when (d ≧ w).

Next, the main control unit 26 moves the carriage A in the region R according to the expression (3) based on the width d of the carriage A, the width w of the conveyance path, and the total number n of antennas when detecting the carriage. The number of the section R ₁ (R ₂ , R ₃ , R ₄ ) is the number (i-th) section counted from the left end (see FIG. 9).
That is, the main control unit 26 obtains a value of i that satisfies Equation (2). The passing section of the carriage A is the section R ₁ when (i = 1), the section R ₂ when (i = 2), and the section R ₃ (i = 4) when (i = 3). when a compartment R _4.

Next, the main control unit 26 selects an antenna corresponding to the section through which the carriage A passes.
Here, the corresponding antennas are antennas 3a, 3b, 3c, and 3d, respectively, where i = 1, 2, 3, and 4 when the carriage A is present in the detection region of the position detectors 7a and 7b. .
Next, the main control unit 26 turns on only the corresponding antenna 3a (3b, 3c, 3d) among the antennas 3a, 3b, 3c, 3d (connected to the reader / writer 5), and all the antennas 4a, 3a, 3d are connected. An antenna selection control signal is sent to the reader / writer 5 so as to turn off 4b, 4c, 4d (connected to the reader / writer 5), and the antenna switching device 6 is controlled via the reader / writer 5.

Next, in the article information acquisition process, the main control unit 26 controls the reader / writer 5 to transmit radio waves (power and article information request signal to the RFID tag 2a via the selected antenna 3a (3b, 3c, 3d). ) And the article information is acquired from the RFID tag 2a via the antenna 3a (3b, 3c, 3d) and the reader / writer 5.
Based on this article information, the main control unit 26 performs, for example, switching control of the conveyance path of the article B for each delivery destination, pickup of a specific article B, and the like.
In addition, the main control unit 26 transmits the acquired article information to the server 11.

In the article information giving process, the main control unit 26 controls the reader / writer 5 to transmit radio waves (power and article information) to the RFID tag 2a via the selected antenna 3a (3b, 3c, 3d). To do.
On the other hand, when the carriage is not detected, the main control unit 26 turns off all the antennas 3a, 3b, 3c, 3d and the antennas 4a, 4b, 4c, 4d (not connected to the reader / writer 5). An antenna selection control signal is sent to the reader / writer 5 to control the antenna switching device 6 via the reader / writer 5.

  Next, the main control unit 26 moves the carriage A along the transport direction, exits the detection region of the position detection units 7a and 7b, detects the detection regions of the position detection units 7a and 7b, and the position detection unit. When entering an intermediate region between the detection regions 8a and 8b, the antenna switching is performed via the reader / writer 5 so that all the antennas 3a, 3b, 3c and 3d and the antennas 4a, 4b, 4c and 4d are turned off. The apparatus 6 is controlled.

  Next, when the carriage A moves along the transport direction and enters the detection area of the position detection parts 8a and 8b from the intermediate area, the main control unit 26 corresponds to the passing section of the carriage A when the carriage is detected. The antenna switching device 6 is controlled via the reader / writer 5 so that only the single antenna 4a (4b, 4c, 4d) is turned on and the antennas 3a, 3b, 3c, 3d are turned off.

Next, when the carriage is not detected, the main control unit 26 turns off all the antennas 3a, 3b, 3c, 3d and the antennas 4a, 4b, 4c, 4d via the reader / writer 5 to turn off the antenna switching device 6. To control.
Next, the main control unit 26 moves all the antennas 3a, 3b, 3c, 3d, and the antenna 4a when the carriage A moves in the transport direction and pulls out of the detection area of the position detection units 8a and 8b. , 4b, 4c, 4d are controlled via the reader / writer 5 so that the antenna switching device 6 is turned off.

The main control unit 26 performs communication several times with each RFID tag 2a (2b) attached to the article B loaded on the carriage A and ends the communication. The main control unit 26 causes the storage unit 27 to store the identification number and the like of the RFID tag 2a (2b) that has responded and has completed communication.
When the main control unit 26 finishes the process for the carriage A, the main control unit 26 performs the same process for the carriage A that moves next.

  Thus, according to the configuration of this example, since a plurality of antennas are arranged above the conveyance path so as to cross the conveyance path, even if the conveyance area at the gate is wide, the article moves in the conveyance area. The product information can be exchanged by reliably communicating with the attached RFID tag.

In addition, since a single antenna corresponding to the section through which the carriage passes is selected from among a plurality of antennas, the radio wave radiation time can be maximized, and the article information reading rate can be improved.
Therefore, for example, even when the article conveyance speed is relatively high, the article information can be read reliably and accurately, and communication can be stabilized.

  Even if multiple antennas are arranged in multiple rows, as the carriage moves (forward), a single antenna is selected and switched for each row, antennas other than the selected antenna are turned off, and the cart is not At the time of detection, radio waves are not radiated from the antenna, so that radio wave interference between the antennas can be reliably prevented while suppressing costs.

In addition, since no radio wave is radiated from the antenna when the carriage is not detected, for example, even when another gate is arranged nearby, radio wave interference can be reliably prevented.
In addition, when the carriage is not detected, radio waves are not radiated from the antenna, which can contribute to power saving.

  Moreover, since it is sufficient that a predetermined communicable area is secured by using the antenna closest to the carriage, the intensity of the radiated electric field and magnetic field can be made relatively weak. Therefore, adverse effects on the human body can be avoided and safety can be improved.

In addition, since the article passes through the gate in a state in which the side on which the RFID tag is attached faces the reader / writer, the communicable area is set to the minimum necessary size so that the electric field and magnetic field can be reduced. The strength of can be suppressed.
In addition, since the reader / writer of the communication partner of the RFID tag is not switched, stable communication can be performed.

The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and there are design changes and the like without departing from the gist of the present invention. Are also included in the present invention.
For example, in the above-described embodiment, the controller performs a cart position information acquisition process, a cart width calculation process, a cart detection process, a passing line identification process, an antenna switching control process, an article information acquisition process, an article information awarding process, and the like. Although the case where the control unit performs by executing the corresponding control program has been described, the cart position information acquisition process, the cart width calculation process, the cart detection process, the passing line identification process, the antenna switching control process, the article information acquisition process Alternatively, part or all of the article information giving process or the like may be performed using dedicated hardware, and a part of the article information giving process may be processed by executing a corresponding program.

Also, separate CPUs may execute cart position information acquisition processing, cart width calculation processing, cart detection processing, passing line identification processing, antenna switching control processing, article information acquisition processing, article information transfer processing, and the like. For example, it may be executed by a single CPU.
In the present invention, the wireless tag means a wireless communication medium that communicates with a reading device, a writing device, or a reading / writing device in a non-contact manner, and includes a non-contact type IC card.

Moreover, as a conveying apparatus, you may use a belt conveyor, for example, a roller conveyor other than a trolley | bogie.
Further, the present invention can be used not only for sorting goods but also for tracking cargo moving by a transport vehicle as a transport means. Further, the present invention can be applied to a state where an article to which a wireless tag is attached is not limited to a cart but is mounted on a vehicle.
In addition to the case where the article is placed on the transport means and transported on the transport line, the present invention can be applied, for example, when the article is transported in a suspended state. Further, the present invention can be applied to a case where the article is transported by sliding on an inclined surface, for example.

Moreover, you may comprise so that writing to RF tag is possible. That is, the present invention can be applied not only to reading but also to reading and writing, or to only writing.
Also, the article information reading function and writing function may be carried out by separate devices, or a part of them may be shared.

Further, when the article is aligned in the previous stage so that the RFID tag and the reader / writer face each other, the attitude adjustment processing of the article may be performed using a dedicated attitude adjustment device or manually. good.
Further, the RFID tag is not necessarily limited to the front and rear surfaces of the article, and may be transported while being attached to the side surface.

In addition, the controller may be connected to the server via a network or may be connected to a plurality of servers.
Further, the position detection unit may be arranged separately for detecting the distance and for detecting the presence or absence of the carriage.
Further, as the position detection unit, in addition to the photoelectric sensor including the light emitting unit and the light receiving unit, a sensor using a sound wave or a weight sensor may be embedded in the floor surface.
Further, the controller may directly control the antenna switching unit without using the reader / writer.

For example, even if a plurality of antennas are connected to a reader / writer via an antenna switching device, radio waves may not be emitted except for a predetermined antenna.
For example, when a cart having a width exceeding the width of the antenna passes, one antenna may be used. The reader / writer may include an antenna switch.

Moreover, although the case where an antenna is arrange | positioned using a support | pillar was described, you may attach to the wall surface of the building of a store or a factory, for example.
Further, as a moving body that moves on the conveyance path, an RFID tag may be attached to a member, an apparatus, or a living thing including a person or an animal in addition to a normal baggage, and information related to the moving body may be exchanged. .

  In addition to the electromagnetic induction method, the present invention can be applied when electric power is supplied to the RFID tag by a radio wave propagation method. In addition to a passive RF tag, the present invention can be applied to an active RFID tag. In addition to a production line of a factory, the present invention can be applied to a management system such as a warehouse for storing articles and the like, and a sorting system for articles in a distribution channel. Moreover, the present invention can be applied to a personal recognition system, an entrance / exit management system, an animal recognition system, an animal management system, etc. in addition to an article sorting system.

It is explanatory drawing for demonstrating the structure of the RFID communication system which is one Example of this invention. It is explanatory drawing for demonstrating the structure of the RFID communication system. It is a block diagram which shows the structure of the RFID communication system. It is a block diagram which shows the structure of the RFID tag of the RFID communication system. It is a block diagram which shows the structure of the reader / writer of the RFID communication system. It is a block diagram which shows the structure of the controller of the RFID communication system. It is a processing procedure figure for demonstrating operation | movement of the RFID communication system. It is explanatory drawing for demonstrating operation | movement of the RFID communication system. It is explanatory drawing for demonstrating operation | movement of the RFID communication system.

Explanation of symbols

1 RFID communication system (wireless communication system)
2a RFID tag (wireless tag, first wireless tag)
2b RFID tag (wireless tag, second wireless tag)
3a, 3b, 3c, 3d antenna (part of the first antenna group)
4a, 4b, 4c, 4d Antenna (part of the second antenna group)
5 Reader / writer (goods information transfer means)
6 Antenna switching device (antenna switching means)
7a, 7b Position detection unit (position detection means, position sensor)
8a, 8b Position detection unit (position detection means, position sensor)
9 Controller 16 Storage section (storage means)
26 Main control unit (antenna selection means, control means)
27 Storage Unit A Cart (Conveyor)
B article

Claims (17)

The article information is received or / and transmitted via radio between an article moving on the conveyance path or a packaging of the article and a wireless tag having storage means for storing article information relating to the article. A wireless communication system for
A plurality of antennas installed along the conveyance path, article information transfer means for receiving and / or transmitting the article information via the predetermined antenna, and the wireless tag or the wireless tag attached thereto Based on the position detection means for detecting the position of the article and the position detection information output from the position detection means, among the plurality of antennas, it should be used for communication between the article information transfer means and the wireless tag. Based on the antenna selection means for selecting the antenna and the position detection information, when the wireless tag or the article to which the wireless tag is attached is detected, an electromagnetic wave for communication with the wireless tag is generated. And a control means for controlling the article information exchanging means so as to radiate from the selected antenna.   When the wireless tag or the article is not detected based on the position detection information, the control means exchanges the article information so as not to radiate electromagnetic waves for communication with the wireless tag from the plurality of antennas. 2. The wireless communication system according to claim 1, wherein said means is controlled.   Antenna switching means for switching and connecting each antenna to the article information exchanging means, and the control means controls the article information exchanging means to the antenna switching means by the antenna selecting means. The radio communication system according to claim 1 or 2, wherein the selected antenna is switched.   The wireless communication system according to claim 1, 2 or 3, wherein the antenna selecting means selects a single antenna among the plurality of antennas.   5. The antenna selection unit according to claim 1, wherein the antenna selection unit selects the antenna closest to a moving path of the article to which the wireless tag or the wireless tag is attached from the plurality of antennas. The wireless communication system according to claim 1.   The conveyance path is divided into a plurality of sections, and the antennas are associated with the sections and arranged so as to cross the conveyance path above the conveyance path. Item 6. The wireless communication system according to any one of Items 1 to 5.   A first wireless tag and a second wireless tag are attached to the front side and the rear side of the article, respectively, and the plurality of antennas are arranged in two rows: a first antenna group and a second antenna group. The antenna of the first antenna group is used for communication with the first wireless tag, and the antenna of the second antenna group communicates with the second wireless tag. The wireless communication system according to claim 6, wherein the wireless communication system is used for: A plurality of the articles are stacked on the transport body and moved along the transport path, and the position detection means includes at least a pair of position sensors that detect distances to the transport body disposed on both sides of the transport path. Become
The antenna selecting means detects the position of the conveyance path based on the distance information output from the pair of position sensors,
The control means calculates the width of the transport body based on the distance information output from the pair of position sensors, and the transport body is detected when the width of the transport body is equal to or less than a predetermined value. 8. The wireless communication system according to claim 1, wherein when the width of the carrier exceeds a predetermined value, it is determined that the carrier is not detected. . The article information is received or / and transmitted via radio between an article moving on the conveyance path or a packaging of the article and a wireless tag having storage means for storing article information relating to the article. An antenna switching control method in a wireless communication system for
A position detection step for detecting the position of the wireless tag or the article to which the wireless tag is attached;
Based on the position detection information obtained in the position detection step, among the plurality of antennas installed along the transport path, the article information exchange means for receiving or / and transmitting the article information and the wireless tag An antenna selection step for selecting the antenna to be used for communication;
When the wireless tag or the article to which the wireless tag is attached is detected based on the position detection information, an electromagnetic wave for communication with the wireless tag is radiated from the selected antenna. An antenna switching control method in a wireless communication system, comprising: a control step of controlling the article information transfer means.   In the control step, when the wireless tag or the article is not detected based on the position detection information, the article information exchange is performed so that electromagnetic waves for communication with the wireless tag are not radiated from the plurality of antennas. 10. The antenna switching control method in a wireless communication system according to claim 9, wherein the means is controlled.   The article information exchanging means is connected to an antenna switching means for switching and connecting the antennas. In the control step, the article information exchanging means is controlled, and the antenna switching means is connected to the antenna selecting step. The antenna switching control method in a radio communication system according to claim 9 or 10, wherein the antenna is selected to be switched.   12. The antenna switching control method in a radio communication system according to claim 9, 10 or 11, wherein, in the antenna selection step, a single antenna among the plurality of antennas is selected.   13. The antenna selection step of selecting the antenna closest to the moving path of the wireless tag or the article to which the wireless tag is attached among the plurality of antennas. An antenna switching control method in the wireless communication system according to claim 1.   The conveyance path is divided into a plurality of sections, and the antennas are associated with the sections and arranged so as to cross the conveyance path above the conveyance path. Item 14. A method for controlling antenna switching in a wireless communication system according to any one of Items 9 to 13.   A first wireless tag and a second wireless tag are attached to the front side and the rear side of the article, respectively, and the plurality of antennas are arranged in two rows: a first antenna group and a second antenna group. The antenna of the first antenna group is used for communication with the first wireless tag, and the antenna of the second antenna group communicates with the second wireless tag. 15. The antenna switching control method in a wireless communication system according to claim 14, wherein the antenna switching control method is used for the above. A plurality of the articles are stacked on the transport body and moved along the transport path, and at the position detection step, at least a pair of position sensors that detect distances to the transport body disposed on both sides of the transport path are provided. Use
In the antenna selection step, based on the distance information output from the pair of position sensors, the position of the conveyance path is detected,
In the control step, the width of the transport body is calculated based on the distance information output from the pair of position sensors, and the transport body is detected when the width of the transport body is equal to or less than a predetermined value. 16. The wireless communication system according to claim 9, wherein when the width of the carrier exceeds a predetermined value, it is determined that the carrier is not detected. Antenna switching control method. The article information is received or / and transmitted via radio between an article moving on the conveyance path or a packaging of the article and a wireless tag having storage means for storing article information relating to the article. A control program for causing a computer to execute an antenna switching control method in a wireless communication system for
A position detection step for detecting the position of the wireless tag or the article to which the wireless tag is attached;
Based on the position detection information obtained in the position detection step, among the plurality of antennas installed along the transport path, the article information exchange means for receiving or / and transmitting the article information and the wireless tag An antenna selection step for selecting the antenna to be used for communication;
When the wireless tag or the article to which the wireless tag is attached is detected based on the position detection information, an electromagnetic wave for communication with the wireless tag is radiated from the selected antenna. A control program for causing a computer to execute a control step for controlling the article information transfer means.

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