JP5270128B2 - Wireless IC tag reader - Google Patents

Description

  The present invention relates to a wireless IC tag reading device, and more particularly to a wireless IC tag reading device for reading a so-called wireless IC tag (also referred to as an electronic tag or RFID).

  In recent years, wireless IC tags have been used for various purposes. One application of the wireless IC tag is a warehouse management system (for example, Patent Document 1). From the warehouse management system using wireless IC tags, the number of stocks and the amount of stock can always be accurately grasped on the database. As a result, the inventory space is minimized, the time for inventory is reduced, the inventory management, and the efficiency of ordering work are improved. Further, since the number of orders is already determined for each storage box, it is also possible to prevent an input mistake in the number of orders.

  When used in such an application, a reader / writer (wireless IC tag reader) for reading a wireless IC tag reads a wireless IC tag that may exist in all areas in a wide warehouse. , It must be installed in various places, secure the place and power source that can not be easily reached, such as the ceiling of the warehouse and the wall of the warehouse, and multiple antennas and their connection cables are also effective wireless IC tag It must be installed in a place where it can be read. In addition, the length of the connection cable between the reader / writer and the antenna attenuates the transmitted signal, and the long distance connection increases the attenuation and prevents the reader / writer from degrading. The connection cable between writers is preferably as short as possible.

  In such a case, unless a power outlet is provided in various places, the power cable for supplying power to the reader / writer must be connected to each reader / writer from a distance, and also connected to the antenna and the antenna. The reader / writer also has a LAN cable that transmits information between the reader / writer and a reader / writer control device (for example, a PC) that processes information of the wireless IC tag read by the reader / writer. Had to connect.

Therefore, a method called PoE (Power Of Ethernet (Ethernet is a registered trademark)) that supplies power to devices using a communication cable has been proposed (see IEEE802.3af). If a reader / writer having a PoE function is used, power can be supplied to the reader / writer through an Ethernet cable for transmitting and receiving data. By installing a reader / writer and an antenna as a single unit, installing a reader / writer for network connection in a place where it is difficult to secure a power supply is possible by installing only one network cable. This method is also effective from the viewpoint of reducing labor and cost.
JP 2001-353850 A

  The reader / writer for reading a passive type wireless IC tag can expect a response from a distant wireless IC tag as its output increases, and can expect a response from many tags in a short time. Since the power that can be generated is limited to feeding by a pair of electric wires included in the Ethernet cable, there is a risk that the power may be insufficient when large power is required.

  Also, when the reader / writer main body (circuit portion) and the antenna are separated from each other and are connected by a cable, a cable loss occurs. If the cable length is 5 m to 10 m, it is 2 to 3 dB. In order to compensate for this, the output of the reader / writer main body must be increased. However, as mentioned above, the power that can be supplied by PoE is limited, and the maximum output level is regulated by legal regulations. Therefore, there is a problem that it is difficult to make the output of the entire reader / writer sufficiently large.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a reader / writer that can not only reduce construction labor and parts such as cables, but also can ensure a sufficient output even with electric power that can be supplied by PoE.

As means for solving the above problems, the present invention has the following features.
The present invention is proposed as a wireless IC tag reading device (for example, a reader / writer) in which an antenna and a main body (for example, a transmission / reception unit, a main control unit, and a communication processing unit) are integrated.

The wireless IC tag reader is connected to a connector (for example, an Ethernet type connector) for connecting a communication cable (for example, an Ethernet cable (Ethernet is a registered trademark, Ethernet or the same applies to the following)) Transmission / reception means (for example, a transmission / reception unit) that transmits / receives to / from the wireless IC tag via the antenna using any one of the unit radio channels, and beam direction change unit (for example, a beam direction change unit) that changes the beam direction of the antenna ), A control unit (for example, a main control unit) for instructing the transmission / reception unit of a unit wireless channel used for transmission / reception with the wireless IC tag, a transmission / reception unit, a beam direction changing unit, and a power supplied via the communication cable; Power supply means (for example, a power supply unit) that supplies power to the control means. Includes a plurality of unit antennas having directivity, and the plurality of unit antennas have a maximum beam direction (a direction in which the power of radio waves radiated in the air is the largest) of each of the plurality of unit antennas centering on the antennas. and such a so that the and different directions Ri spread (e.g., a fan) is provided, the beam redirecting means determines whether failure reading of the wireless IC tag, the reading of the wireless IC tag In order to avoid a decrease in electric field strength in the wireless IC tag due to interference between a direct wave reaching the wireless IC tag from the antenna and a reflected radio wave when the antenna is determined to have failed. One of them is selectively electrically connected to the transmission / reception means to change the maximum beam direction .
The maximum beam direction may be rotated in at least one of the vertical direction and the horizontal direction.

  Here, “integrated” means that no work, tools, cables, etc. are required for connecting the antenna and the main body when the reader / writer is installed. For example, the antenna is not installed in the reader / writer housing. The purpose is not limited to the case of being built-in. The “main body” refers to a component having a main circuit portion.

  According to this wireless IC tag reading device, the wireless IC tag reading device can be easily installed at any place as well as reducing the labor of construction and parts such as cables by using the power that can be supplied by PoE. Can provide.

In the above wireless IC tag reading apparatus, the antenna may be disposed in the casing together with the transmission / reception means so that the signal is not attenuated between the transmission / reception means. . According to the wireless IC tag reading device having such a feature, since there is no signal attenuation between the antenna and the transmitting / receiving means, the output of the entire device can be secured even if the output of the transmitting / receiving means is small. Further, since the output of the entire apparatus can be ensured even if the output of the transmission / reception means is small, it is possible to provide a wireless IC tag reading apparatus capable of obtaining sufficient output even with limited power supply by so-called PoE.

In the above wireless IC tag reading device, the control means is configured to self-determine from a unit radio channel used by another wireless IC tag reading device or a channel separated by two or more channels from a unit wireless channel to be used. The unit radio channel to be used may be determined.

  According to such a wireless IC tag reading apparatus, effective scheduling of frequencies (channels) including LBT and frequency hopping can be performed by exchanging the meaning information of mutual use unit wireless channels using a communication cable. Linking becomes possible, and channel movement and the like due to collision recognition at the time of LBT due to selection of a random channel so far are reduced.

In the above wireless IC tag reader, for example, the output of the transmission / reception means may be 30 dB or less, and the output of the wireless IC tag reader may be 36 dB or less.
According to such a wireless IC tag reading device, the power supplied to the transmission / reception means can maintain at least an output conforming to the standard.

  According to the present invention, it is possible not only to reduce the labor of construction and parts such as cables, but also to secure a sufficient output for reading a wireless IC tag by the power that can be supplied by PoE.

First, an example of a basic configuration of the wireless IC tag reading system in this embodiment will be described.
[1. Wireless IC tag reading system]
FIG. 1 is a functional block diagram showing an example of a basic configuration of a wireless IC tag reading system according to an embodiment of the present invention.

  The wireless IC tag reading system 1 includes a reader / writer control device 10 connected to an Ethernet network 30 (hereinafter simply referred to as “network”), and a reader / writer control device 10 connected to the reader / writer control device 10 via the network 30. And a writer 20. The network 30 includes PoE-compatible HUBs, switches, and the like. Power can be supplied from these devices to the reader / writer 20 via the Ethernet cable 25 (hereinafter simply referred to as “cable”).

  As another configuration example of the wireless IC tag reading system 1 according to the present invention, the reader / writer control device 10 itself has a PoE-compatible power supply unit, and the reader / writer 20 and the reader / writer control device. 10 may be directly connected by a cable 25.

Hereinafter, each component of the wireless IC tag reading system 1 will be described.
[1.1. Reader / Writer Control Device]
The reader / writer control device 10 collects and stores data acquired by the reader / writer 20 as a result of reading processing of the reader / writer 20, that is, transmission / reception processing with the wireless IC tag 40, and analyzes this in some cases. Device. In other words, the reader / writer control device 10 reads the reader / writer 20 (transmitting a carrier wave for setting the wireless IC tag in a receiving state, transmitting a modulated wave with a question command, supplying power to the wireless IC tag. To transmit a carrier wave to be continued, reception of a response from the wireless IC tag), and to instruct the reader / writer 20 to transmit the data read from the wireless IC tag 40. It has a function of storing data received from the writer 20 and performing predetermined information processing (for example, generation of a list of unique IDs of wireless IC tags).

  The reader / writer control device 10 and the reader / writer 20 are connected by a cable 25. The cable 25 sends power using a pair of spare lines in the cable 25 (used for data transmission in 10Base-T or 100Base-T Ethernet). Alternatively, a pair of data lines may be used to send power (in addition to data transmission).

  The reader / writer control device 10 is an information processing device including an arithmetic processing device such as a CPU, and a storage device such as a ROM and a RAM, and can further have a function of supplying power to the reader / writer 20. It is. For example, the reader / writer control device 10 is a computer, various controllers, or the like.

  FIG. 2 is a block diagram illustrating a configuration example of the reader / writer control device 10. The reader / writer control device 10 converts a user input, such as a keyboard, pointing device, etc., into a control unit 201 composed of a CPU, a RAM as temporary storage means, a ROM for storing programs and fixed data, and the like. An input device 202 provided to the control unit 201, a screen display device 203 (for example, a liquid crystal display device) for showing the processing result of the control unit 201 to the user, and a communication control unit for communicating with the reader / writer 20 204 (for example, a LAN board).

[1.2. Reader / Writer]
Next, the reader / writer 20 according to the present embodiment will be described. The reader / writer 20 corresponds to the wireless IC tag reading device of the present invention.
The reader / writer 20 is a device that performs wireless transmission and reception with the wireless IC tag 40 and reads information stored in the wireless IC tag 40 (for example, a unique ID). The reader / writer 20 can selectively use a plurality of unit radio channels (frequency bands) that can be used when transmitting and receiving with the wireless IC tag 40. For example, taking a reader / writer that reads a so-called high-power 950 MHz band passive tag as an example, the reader / writer 20 divides nine unit radio channels obtained by dividing a radio band 952 to 954 MHz allocated for transmission and reception by a 200 KHz width. It can be used selectively.

  FIG. 3 is a block diagram showing a configuration example of the reader / writer 20. The reader / writer 20 includes a main control unit 101, a transmission / reception unit 102 connected to the control unit 101, an antenna 103 connected to the transmission / reception unit 102, a beam direction changing unit 104 that changes the beam direction of the antenna 103, A communication processing unit 105 connected to the main control unit 101, a beam direction changing unit 104, a transmission / reception unit 102, a main control unit 101, a power supply unit 106 that supplies power to the communication processing unit 105, and a communication processing unit 105 And a connector 107 connected to the power supply unit 106. Each component excluding the antenna 103 constitutes a “main body” of the reader / writer.

  The main control unit 101 is, for example, a microcomputer having a CPU, a ROM, and a RAM. The main control unit 101 receives a command from the reader / writer control device 10, drives the transmission / reception unit 102 in response thereto, and communicates data (data read from the wireless IC tag 40) output from the transmission / reception unit 102. It has a function of transmitting to the reader / writer control device 10 via the processing unit 105.

  The control unit 101 also has a function of transmitting a direction change command to the beam direction changing unit 104 and causing the beam direction changing unit 104 to change the beam direction of the antenna 103.

  The main control unit 101 determines any unit radio channel to be used for transmission / reception from a plurality of unit radio channels. In determining the unit radio channel, a unit radio channel separated by a predetermined number of channels from the radio channels used by other reader / writers 20 may be selected. The main control unit 101 notifies other reader / writers 20 of the unit radio channel that is being used or scheduled to be used, and also notifies the unit radio channels (other reader / writers 20) notified from the other reader / writer 20. The writer 20 is currently in use or scheduled to use), and based on the stored unit radio channel, it has a function of determining a unit radio channel used by itself. For example, in this embodiment, the main control unit 101 selects a unit radio channel that is two or more channels away from a unit radio channel used by another reader / writer 20. When such a unit radio channel does not exist, transmission / reception may be waited until such a unit radio channel becomes available, or another open unit radio channel may be used. Further, the number of channels apart from each other need not be two, but may be other numbers.

  FIG. 4 is a diagram showing how unit radio channels are selected by three reader / writers 20. The three reader / writers 20 are arranged within a range that is affected by the transmission radio waves of the other reader / writers 20 in the wireless IC tag reading process. The three reader / writers 20 notify the other reader / writers 20 of unit radio channels used by themselves via the network 30.

FIG. 4A shows that one of the three reader / writers 20 (referred to as the first reader / writer 20) uses the channel CH6 among the nine unit radio channels.
At this time, the other two reader / writers 20 (referred to as a second reader / writer and a third reader / writer) are notified that the channel CH6 is being used by the first reader / writer.

  FIG. 4B is a diagram for explaining determination of a unit radio channel used by the second reader / writer. As shown in FIG. 4A, when the first reader / writer uses the channel CH6, the second reader / writer uses the unit radio channel that the second reader / writer uses at least two channels away from the channel CH6. Choose as. Here, channel CH3 and channel CH9 meet the conditions, but channel CH9 is selected. The second reader / writer notifies the first and third reader / writers that he / she is using channel CH9.

  Next, in the state where the first reader / writer uses channel CH6 and the second reader / writer uses CH9, the unit radio channel used by the third reader / writer for transmission / reception is determined. try to. FIG. 4C is a diagram for explaining determination of a unit radio channel used by the third reader / writer. Assume that the third reader / writer is the channel CH6, and the unit radio channels separated from the channel CH9 by two or more channels are the channels CH1, CH2, and CH3, and the third reader / writer selects the channel CH3.

  Each reader / writer 20 uses a unit radio channel that is a predetermined channel away from a unit radio channel used by another reader / writer, thereby being affected by the transmission radio wave of the other reader / writer 20. The reading processing of the wireless IC tag 40 can be performed without any problem.

Returning to FIG. 3, the description of the configuration example of the reader / writer 20 will be continued.
The transmission / reception unit 102 has a function of transmitting and receiving data wirelessly with the wireless IC tag 40 via the antenna 103. More specifically, the transmission / reception unit 102 includes a modulation unit 108, a demodulation unit 110, and a frequency change unit 109.

  The modulation unit 108 generates a modulated wave obtained by modulating a carrier wave with a predetermined modulation method using a base signal corresponding to information such as a predetermined command, request, or command received from the control unit 101. The transmission unit 108 includes, for example, a modulation circuit, an amplifier circuit, a low-pass filter, and the like.

  The demodulator 110 has a function of demodulating the load-modulated magnetic field based on the base signal corresponding to the data stored in the wireless IC tag 40, taking out the base signal corresponding to the data, and passing it to the controller 101. . The demodulator 110 includes, for example, a demodulator circuit and an amplifier circuit.

  The frequency changing unit 109 generates a reference signal according to the center frequency of the unit radio channel used for transmission / reception with the radio IC tag in response to a command from the main control unit 101 and supplies the reference signal to the modulation unit 108 and the demodulation unit 110. It has the function to do. The frequency changing unit 109 is a module on which, for example, a PLL (Phase Lock Loop) IC and a VCO (Voltage Control Oscillator) IC are mounted.

  The antenna 103 radiates a modulated wave received from the transmission / reception unit 102, more specifically, the modulation unit 106 in the air, and radiates a radio wave toward the wireless IC tag 30. In addition, the antenna 103 receives a radio wave on which a weak reception signal is superimposed by the radio IC tag 30 being subjected to load modulation by the radio wave transmitted from the antenna 103, converts the radio wave into a weak electric signal, More specifically, it is sent to the demodulator 110.

  The antenna 103 is connected so that the transmission signal and the reception signal are not attenuated as much as possible when the signal is exchanged with the transmission / reception unit 102. For example, the antenna 103 is arranged in the housing of the reader / writer 20 and arranged so that the connection line with the transmission / reception unit 102 is as short as possible.

  The antenna 103 is an antenna having directivity, and may have a maximum beam direction that is a direction in which the electric power of the radio wave radiated in the air becomes the largest. The antenna 103 is, for example, a dipole antenna, a patch antenna, or the like, and is a phased array antenna that is a combination of one or more.

  The maximum beam direction of the antenna 103 is changed by the beam direction changing unit 104. This change may be performed either mechanically or electrically.

  In general, when the reader / writer 20 is used in a closed space such as a warehouse, the reading radio wave radiated from the reader / writer 20 is reflected by a wall or a floor and becomes a reflected wave, causing interference with the direct wave. It is known that a large number of null points are generated, which are points where the electric field strength rapidly decreases. When the wireless IC tag 40 is located at such a null point, reading of the wireless IC tag 40 fails.

  Therefore, the beam direction changing unit 104 changes the beam direction of the antenna 103 to a direction in which the reflected wave from the floor is not generated, so that the reflected wave from the floor and the direct wave reaching the wireless IC tag directly from the antenna 103 can be reduced. A reduction in electric field strength in the wireless IC tag due to interference can be avoided, and as a result, a sufficient electromotive force is supplied to the IC chip of the wireless IC tag, so that a response from the wireless IC tag reaches the antenna 103. Will be able to.

  In this embodiment, the antenna 103 is composed of three directional antennas each having a half-value angle of about 60 degrees. FIG. 5 is an explanatory diagram illustrating a configuration example of the antenna 103. The antenna 103 is composed of antennas (hereinafter referred to as unit antennas 501) each having a beam pattern having a half-value angle of about 60 degrees. The three unit antennas 501 are provided in the reader / writer 20 so that the maximum beam direction extends in a fan shape and becomes different directions.

  Each unit antenna 501 is connected to a switch circuit which is the beam direction changing unit 104. The switch circuit selectively connects one of the unit antennas 501 to the transmission / reception unit 102 in accordance with a control signal from the main control unit 101. The magnitude of the half-value angle of each unit antenna 501 and the number of unit antennas are not limited to those of this embodiment, and the present invention can be realized regardless of the value and number of half-value angles. To do.

  The direction in which the maximum beam direction is rotated is the vertical direction in this embodiment, but may be configured to rotate in the horizontal direction, and may be rotated in both the vertical direction and the horizontal direction. And may be combined.

Returning to FIG. 3, the description of the configuration example of the reader / writer 20 will be continued.
The communication control unit 105 is a device that communicates with the reader / writer control device 10 and is, for example, a LAN board.
The power supply unit 106 supplies power supplied via the cable 25 in a form that can be used by the main control unit 101, the transmission / reception unit 102, the beam direction changing unit 104, and the communication processing unit 105 (which performs power conversion). For example, an A / D converter, a transformer, or a rechargeable battery.

  The connector 106 is a connection port to which the cable 25 can be connected, and is, for example, an Ethernet type connector.

[1.5. Wireless IC tag]
Next, a general configuration example of the wireless IC tag 40 will be described with reference to FIG. FIG. 6 is a block diagram illustrating a configuration example of a wireless IC tag.

The wireless IC tag 40 includes a memory 41, a control unit 42, a transmission / reception unit 43, and an antenna 44. The memory 41 is a storage device that stores information to be read such as identification information such as product information and shipper information. The control unit 42 interprets commands, requests, commands, etc. from the reader / writer 20 and executes operations in response thereto. The transmission / reception unit 43 includes a modulation unit (not shown) and a demodulation unit (not shown), and modulates / demodulates signals in order to communicate with the reader / writer 20. The antenna 44 receives the modulated wave from the reader / writer 20, feeds it to the transmission / reception unit 43, receives the modulation signal from the transmission / reception unit 43, and radiates it into the air so that the reader / writer 20 receives it. .
Above, description of the structural example of the radio | wireless IC tag reading system 1 is complete | finished.
[2. Modified example]

  In the case of a configuration in which the maximum beam direction of the antenna 103 is mechanically changed, the beam direction changing unit 104 is configured by a stepping motor and its control circuit, and rotates the antenna 103 that is rotatably attached to a shaft or the like. The maximum beam direction of the antenna 103 with respect to the wireless IC tag 40 is changed.

On the other hand, in the case of a configuration in which the maximum beam direction of the transmitting antenna 103 is electrically changed, the beam direction changing unit 104 includes a distribution synthesizer and a plurality of phase shifters. The transmitting antenna 103 is composed of a plurality of antenna elements arranged in an array. The modulated wave input to the distribution synthesizer is distributed to the phase shifter for each antenna element, and after a desired phase change (phase shift) is made in each phase shifter, it is radiated from each antenna element. By changing the phase shift change of each phase shifter according to the command of the main control unit 101, the direction in which the radio wave is radiated strongly is changed in the direction in which the phase shift of the radio wave radiated from each antenna element coincides. Is possible.
[3. advantage]

  (1) According to the present invention, the reader / writer main body (transmission / reception unit, beam direction changing unit, main control unit, communication processing unit) and the antenna 103 are integrated to connect the antenna and the reader / writer main body. Therefore, it is possible not only to reduce the labor for construction and parts such as cables, but also to add 36 dB to the output of the reader / writer and the gain of the antenna.

  (2) The reader / writer main body and the antenna are integrated, and considering an example in which a plurality of antennas are installed in one room, the reader / writer main body and the antenna can be installed freely only by wiring a thin Ethernet cable.

  (3) Since a plurality of readers / writers 20 are connected to each other via the network 20, effective scheduling of frequency (channel) including LBT and frequency hopping and linkage are possible, and randomization so far By selecting a correct channel, channel movement due to collision recognition at the time of LBT is reduced.

Block diagram showing a configuration example of a wireless IC tag reading system Block diagram showing a configuration example of a reader / writer control device Block diagram showing a configuration example of a reader / writer The figure which shows the example which determines the unit radio channel which a reader / writer uses. Diagram showing an example of antenna configuration Block diagram showing a configuration example of a wireless IC tag

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Wireless IC tag reading system 10 ... Reader / writer control apparatus 20 ... Reader / writer 25 ... Communication cable 40 ... Wireless IC tag 103 ... Antenna

Claims (4)

A wireless IC tag reading device in which an antenna and a main body are integrated,
A transmission / reception means connected to a connector for connecting a communication cable and performing transmission / reception with a wireless IC tag via an antenna using any one of a plurality of unit wireless channels;
Beam direction changing means for changing the beam direction of the antenna;
Control means for instructing the transmission / reception means about a unit radio channel used for transmission / reception with the wireless IC tag;
Power supply means for supplying power supplied via a communication cable to the transmission / reception means, beam direction changing means, and control means;
The antenna includes a plurality of unit antennas having directivity,
The plurality of unit antennas, the antenna is provided in so that such a maximum beam directions to and different directions Ri spread from each other of each of said plurality of unit antennas around a,
The beam direction changing means determines whether or not the reading of the wireless IC tag has failed, and determines that the direct wave reaching the wireless IC tag from the antenna when determining that reading of the wireless IC tag has failed. and by the interference of the reflected wave, the so electric field intensity in the wireless IC tag is prevented from being lowered, the maximum beam direction or selectively said electrically connected to receiving means of said plurality of unit antennas A wireless IC tag reading device, characterized in that:   2. The wireless IC according to claim 1, wherein the antenna is disposed in a housing together with the transmission / reception unit, and is disposed at a distance at which signal attenuation does not substantially occur between the antenna and the transmission / reception unit. Tag reader.   The control means determines a unit radio channel used by itself from a unit radio channel used by another radio IC tag reader or a channel separated by two or more channels from a unit radio channel scheduled to be used. The wireless IC tag reader according to claim 1 or 2.   The wireless IC tag reading device according to any one of claims 1 to 3, wherein the maximum beam direction is rotated in at least one of a vertical direction and a horizontal direction.

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