JP2007193498A - Rfid tag system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an RFID tag system for achieving configurations to plan the expansion of a communication validating region with an RFID tag, by using the reflection of radio waves without being upsized. <P>SOLUTION: An RFID tag 5 attached to the back face of a truck 4 is stored with circulation information, and a reader/writer 1 reads circulation information from an RFID tag 5 by radio waves with a UHF band. When a metallic product A is housed in a corrugated cardboard conveyed by the carrier 4, a communication-invalidating region C is formed at the back side of the metallic product A, while the RFID tag 5 is positioned in a communication-validating region B so that communication with the RFID tag 5 can be invalidated. A reflecting means 19, installed on the front face of a transmission antenna 2 of the reader/writer 1, diffuses and reflects the radio waves from the transmission antenna 2 in the horizontal direction so that the radio wave can reach the RFID tag 5 positioned in the communication-invalidating region C, and that communication with the RFID tag 5, which is originally invalid, can be validated. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an RFID tag system that communicates with an RFID tag by radio waves radiated from an antenna of a reader / writer.

In recent years, it has become possible to use a frequency for an RFID tag in the UHF band, and it has become possible to greatly improve the communication distance, so the use of an RFID tag in the UHF band is planned.
As an example, a system has been proposed in which RFID tags are affixed to carts and returnable boxes used in logistics, etc., and reader / writers are installed in the passages through which they pass to read data from and write data to RFID tags. ing. In such a system, a configuration in which an RFID tag is read from one side of a passage is common. In this way, when RFID tags are attached to both sides of a cart and a returnable box, it is necessary to access the RFID tag by time division by installing antennas on both sides of the passage and switching the antenna for communication. There is.
JP 2003-283365 A

  By the way, in the method of attaching the RFID tag to both sides of the cart and the return box, for example, when it is necessary to write data such as passage time to the RFID tag, the data can be written only to the RFID tag on one side. Sometimes, there is a problem that data cannot be read from an RFID tag attached to the opposite side of a cart or a return box at another location.

  Also, in the method of installing the antennas on both sides of the passage, the access blank time required for switching occurs when reading the RFID tag attached to the moving return box in order to switch the antennas in time division. In some cases, the RFID tag cannot be read, such as when the RFID tag exists in another switched antenna area.

  Therefore, although it is desirable to affix the RFID tag only on one side of the cart or return box, if the RFID tag is located on the opposite side of the passage with respect to the antenna, even if it is a communicable distance, There is a possibility that communication with the RFID tag cannot be performed due to the influence of the metal product placed on the carriage.

On the other hand, Patent Document 1 proposes to improve the communication accuracy with the RFID tag by using a parabolic reflecting surface and concentrating radio waves on the reflecting surface.
However, in such a method, the position where radio waves are concentrated is limited and the reflection surface is extremely large. Therefore, a communication environment where the passing position of the RFID tag is indefinite, such as a cart or a return box, or the installation of a reflection surface This is not possible in a communication environment where the area is limited.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an RFID tag system that can be realized without increasing the size of a configuration for expanding the communicable area with the RFID tag by using reflection of radio waves. There is to do.

  According to the first aspect of the present invention, since the radio wave transmitted from the reader / writer is diffused and reflected in different directions by the protruding reflecting surface of the reflecting means, the reader / writer is opposed to the communicable area or the RFID tag. The angle can be expanded, and communication with an RFID tag that is otherwise impossible to communicate becomes possible.

According to the invention of claim 2, since the reflection direction of the radio wave by the reflecting means is changed, the radio wave is sequentially reflected in different directions, and communication with an RFID tag that is otherwise impossible to communicate is possible.
According to the invention of claim 3, since the communication environment does not change until the reader / writer communicates with the RFID tag, the reader / writer can guarantee the communication until the communication with the RFID tag is completed.

According to the fourth and fifth aspects of the present invention, radio waves can be effectively diffused by the reflection of the reflecting surface of the reflecting means.
According to the sixth aspect of the present invention, radio waves can be concentrated by the reflector of the reflecting means, so that the communication performance with the RFID tag located at the radio wave concentration position can be improved.

  According to the seventh aspect of the present invention, even when the antenna is composed of a transmission antenna and a reception antenna, it is possible to improve the communication performance with an RFID tag located at a concentrated position of radio waves.

According to the invention of claim 8, the radio wave can be efficiently diffused in the horizontal direction by the reflecting means.
According to the invention of claim 9, the reflection direction of the radio wave can be changed stepwise by rotating the reflecting means.

According to the invention of claim 10, since the reflecting means is stopped until the communication with the RFID tag is completed, the communication can be guaranteed until the communication with the RFID tag is completed.
According to the eleventh aspect, the overall configuration can be simplified.

(First embodiment)
A first embodiment of the present invention will be described below with reference to FIGS.
FIG. 1 schematically shows the configuration of the entire system. In FIG. 1, a reader / writer (corresponding to control means) 1 is installed on the side of the passage. The reader / writer 1 includes a transmission antenna 2 and a reception antenna 3, and transmits a query signal to a transmission signal having a predetermined frequency in a UHF (Ultra High Frequency) band of 952 to 954 MHz, for example, as a communication radio wave from the transmission antenna 2. The signal is modulated and transmitted, and the response signal from the RFID tag is received by the receiving antenna 3 and demodulated.

The characteristics of communication using this UHF band are:
1. The radio wave has directivity, and the communication area can be limited to some extent.
2. Since the communication distance can be increased, it is easy to set a relatively wide range as a communicable region.
3. For example, the RFID tag can be read by passing through a paper or board such as cardboard, plastic, or the like.

  An RFID tag 5 is attached to one side of the carriage 4 that passes through the passage. The RFID tag 5 stores logistics information of articles mounted on the cart 4, and by reading the logistics information, it is possible to manage the contents, transport destination, transport time, etc. of the articles mounted on the cart 4. Become.

FIG. 2 schematically shows the configuration of the reader / writer 1. In FIG. 2, the reader / writer 1 includes a control unit 6, a storage unit 7, a transmission unit 8, and a reception unit 9.
The transmission unit 8 includes a digital unit 10 and an analog unit 11. The digital unit 10 includes an encoding unit 10a and a modulation unit 10b, and the analog unit 11 includes a filter 11a and an amplifier 11b. The receiving unit 9 includes a digital unit 12 and an analog unit 13. The digital unit 12 includes a decoding unit 12a and a demodulation unit 12b, and the analog unit 13 includes a filter 13a and an amplifier 13b. The transmission antenna 2 is connected to the transmission unit 8 of the reader / writer 1, and the reception antenna 3 is connected to the reception unit 9 of the reader / writer 1.
In FIG. 2, the transmission antenna 2 and the reception antenna 3 are shown independently. Or is configured.

  FIG. 3 schematically shows the configuration of the RFID tag 5. In FIG. 3, the RFID tag 5 includes an antenna 14, a control unit 15, a storage unit 16, a demodulation unit 17, and a modulation unit 18. The RFID tag 5 is a passive type that does not use a battery that generates its own power from a transmission signal from the reader / writer 1, but an active type that incorporates a battery is used when the communication distance is long.

  Returning to FIG. 1, the reflecting means 19 is installed at a position opposite to the path of the carriage 4 in the front direction of the transmitting antenna 2 and the receiving antenna 3. As shown in FIG. 4, the reflecting means 19 is formed long in the height direction and has a semi-cylindrical reflecting surface 19a protruding toward the reader / writer 1 side. The reflection surface 19a is made of a metal surface such as iron or aluminum, and may be formed by arranging metal wires in a lattice shape as long as radio waves can be reflected.

Next, the operation of the above configuration will be described.
The reader / writer 1 modulates a transmission signal with a predetermined frequency of 952 to 954 MHz (UHF band) from the transmission antenna 2 and transmits the modulated signal. The UHF band radio wave transmitted from the transmission antenna 2 has excellent directivity, and is radiated about the front of the transmission antenna 2 as the center.

  An RFID tag 5 is attached to one side of the carriage 4 that passes through the passage. In this case, the RFID tag 5 is affixed to one side of the cart 4 as described in [Problems to be Solved by the Invention], which is a problem that occurs when the RFID tag 5 is affixed to both sides of the cart 4. This is to avoid it. In this embodiment, it is assumed that the RFID tag 5 is attached to a portion on the opposite side of the path of the carriage 4.

  The reader / writer 1 transmits a UHF band radio wave from the transmitting antenna 2 and communicates with the RFID tag 5 attached to the cart 4 to read the data, whereby the type, number, and destination of the products carried by the cart 4 are read. And the like, and data such as passage time are written into the RFID tag 5.

  By the way, when the metal product A is stored in the cardboard mounted on the cart 4, since the radio wave cannot pass through the metal product A, the RFID tag 5 can communicate with the reader / writer 1 in the communicable region B (FIG. 1 within the range indicated by a solid line), communication with the RFID tag 5 becomes impossible. That is, an incommunicable area C (area indicated by hatching in the drawing) is formed on the back side of the metal product A, and the RFID tag 5 is positioned in the incommunicable area C. This incommunicable area C is always formed on the back side of the RFID tag 5 even if the carriage 4 moves, so that the RFID tag 5 is always located in the incommunicable area C. For this reason, the reader / writer 1 cannot communicate with the RFID tag 5 even if the carriage 4 passes forward, and cannot read logistics information from the RFID tag 5 or write data to the RFID tag 5. End up.

  However, in the present embodiment, since the reflecting means 19 is installed in front of the transmitting antenna 2 and the receiving antenna 3, the radio wave radiated from the transmitting antenna 2 is reflected by the reflecting surface 19a of the reflecting means 19. In this case, since the reflecting surface 19a of the reflecting means 19 has a semi-cylindrical shape protruding toward the reader / writer 1, the radio wave reflected by the reflecting surface 19a is diffused in the horizontal direction around the reflecting means 19. As a result, even when the RFID tag 5 is located in the incommunicable region C, the radio wave from the reader / writer 1 reaches the reflecting means 19. That is, the RFID tag 5 located in the incommunicable area C is located in the communicable area D formed by the reflecting means 19. As a result, the reader / writer 1 can communicate with the RFID tag 5 that cannot normally communicate.

  Here, when the RFID tag 5 is a passive type, the RFID tag 5 is activated by generating power from the received transmission signal, the inquiry signal modulated from the transmission signal in the activated state is demodulated, and a response signal corresponding to the inquiry signal Is transmitted as a received signal by modulation of the transmitted signal.

In FIG. 1, the transmission signal and the reception signal are shown separately for easy understanding of the operation. However, when the RFID tag 5 is a passive type, the paths of the transmission signal and the reception signal are the same. .
When the RFID tag 5 is an active type, the interrogation signal is demodulated from the received transmission signal, and the transmission signal generated from the power of the internal battery is modulated by the response signal and transmitted from the transmission antenna.

  The reader / writer 1 receives the signal from the RFID tag 5 by the receiving antenna 3, demodulates the response signal from the received signal, and recognizes the existence of the RFID tag 5, thereby storing the logistics information stored in the RFID tag 5. Can be read, or the current time can be written in the RFID tag 5.

  Since communication with the RFID tag 5 by the reader / writer 1 as described above is performed in a relatively short time, the metal product A built in the cardboard is moved in front of the transmitting antenna 2 and the receiving antenna 3 as the carriage 4 advances. By being located, even if the communicable area D is not formed by the reflecting means 19 and communication with the RFID tag 5 becomes impossible, no trouble is caused.

According to such an embodiment, the reflection means 19 is installed at a position facing the transmission antenna 2 and the reception antenna 3 across the passage of the carriage 4 so that the radio wave radiated from the transmission antenna 2 does not reach directly. Even when the RFID tag 5 is located at C, communication with the RFID tag 5 is enabled by reflection of radio waves by the reflection means 19, so that the communicable area can be expanded. Therefore, as compared with a configuration in which the reflection means 19 is not provided, the RFID tag 5 attached to the back side of the cart 4 even if the metal product A is stored in the cardboard box conveyed by the cart 4. It is possible to read information from and write information.
In addition, since the radio wave is diffused in the horizontal direction by the reflecting means 19, the communicable area can be effectively expanded even with the small reflecting means 19.

  Incidentally, the reflecting surface of the reflecting means 19 is formed to have a plurality of polygonal reflecting portions 20 as shown in FIG. 5, or in the form of a vertical band as shown in FIG. You may make it do. In this case, the radio wave from the reader / writer 1 can be effectively diffused in the horizontal direction by the surface shape of the reflecting means 19.

  Moreover, you may comprise the shape of the reflective surface of the reflection means 19 so that it may have two or more parabolic reflectors 21 as shown in FIG. In this case, it is desirable that about half of the parabolic reflectors 21 are directed in the direction of the transmitting antenna 2 and the remaining half are directed in the direction of the receiving antenna 3. That is, since the radio waves can be concentrated by the reflector 21, the communication performance with the RFID tag 5 can be improved by setting the concentrated area as the passing area of the RFID tag 5.

(Second embodiment)
Next, a second embodiment of the present invention will be described with reference to FIGS. 8 and 9. The same reference numerals are given to the components having the same names as those of the first embodiment, and detailed description thereof will be omitted. The second embodiment is characterized in that the reflection means 19 is rotationally controlled.

  FIG. 8 is a perspective view of the reflecting means 19. In FIG. 8, the reflecting means 19 has a polygonal columnar reflecting surface 19a. A rotating shaft 22 is provided at the center of the reflecting means 19, and the rotating shaft 22 is rotated by a predetermined angle by a motor (not shown) built in the pedestal 23. This motor is driven by control from the reader / writer 1.

  When radio waves are radiated from the transmitting antenna 2 of the reader / writer 1, the radio waves are reflected by the reflecting surface 19a of the reflecting means 19, so that the radio waves from the reader / writer 1 do not reach directly as described in the first embodiment. Even when the RFID tag 5 is located in the incommunicable region, communication with the RFID tag 5 is possible by reflection of radio waves by the reflecting means 19.

By the way, in a state where the reflection means 19 is stopped, there is a possibility that an area where the radio wave does not reach may occur even if the radio wave can reach by the reflection of the radio wave by the reflection means 19.
Therefore, in this embodiment, the reflection means 19 is rotationally controlled by the reader / writer 1.
FIG. 9 is a flowchart showing a data reading operation by the reader / writer 1. In FIG. 9, the reader / writer 1 first issues an ID read command (S1). When there is no ID response from the RFID tag 5 (S2: NO), the reflecting means 19 is rotated by one step (S6). In this case, since the surface of the reflecting means 19 is formed in a polygonal column shape, when the reflecting means 19 is rotated by one step, the direction of reflection of the radio wave by the reflecting surface 19a of the reflecting means 19 is changed, and the reflection is accordingly performed. The communicable area with the RFID tag 5 by the means 19 changes.
If there is still no response from the RFID tag 5 even if the reflecting means 19 is rotated by one step in this way (S2: NO), the reflecting means 19 is further rotated step by step (S6).

Then, as a result of the rotation control for the reflecting means 19 step by step, when there is an ID response from the RFID tag 5 (S2: YES), a data read command is issued (S3), and the response signal from the RFID tag 5 Is read (S4), the data is transmitted to the host (S5), and then the reading of the RFID tag 5 is continued by returning to step S1.
With the above operation, even when the RFID tag 5 is located in the incommunicable region C, it is possible to communicate with the RFID tag 5 attached to the back side of the carriage 4 by the rotation control with respect to the reflecting means 19. .

According to such an embodiment, the reflection means 19 having the polygonal columnar reflection surface 19a is rotationally controlled so that the reflection direction of the radio waves by the reflection means 19 is changed in order. Compared to the first embodiment in which the communicable area due to reflection is fixed, the communicable area moves in order, and the communicable area can be further expanded.
Moreover, the reflection means 19 is stopped before the communication with the RFID tag 5 is started, and the rotation of the reflection means 19 is controlled again when the communication with the RFID tag 5 is completed, so that the communication with the RFID tag 5 is guaranteed. can do.

In addition, since the reader / writer 1 itself controls the rotation of the reflecting means 19, the overall structure can be simplified as compared with the structure in which the means for controlling the rotation of the reflecting means 19 is provided independently.
As the reflection means 19, the reflection surface may be planar as shown in FIG. 10, and the angle of the reflection means 19 may be controlled by a motor (not shown) built in the pedestal 23.

The present invention is not limited to the above embodiment, but can be modified or expanded as follows.
The surface-shaped reflecting means 19 shown in FIGS. 4 to 6 may be rotationally controlled.
As shown in FIG. 11, a plurality of reflecting means 19 may be installed on the opposite side of the passage, or the angle of the reflecting means 19 may be controlled by the reader / writer 1 as shown in FIG.
As shown in FIG. 13, the reflecting means 19 may be installed on the back side of the transmitting antenna 2 and the receiving antenna 3, or the reflecting means 19 may be rotationally controlled by the reader / writer 1 as shown in FIG.

  The reflecting means 19 may be fixedly installed on both sides of the passage as shown in FIG. 15, or the reflecting means 19 may be rotationally controlled by the reader / writer 1 as shown in FIG. In this case, the communicable area can be further expanded by the reflection of the plurality of reflecting means 19, so communication with the RFID tag 5 attached to the front side of the carriage 4 is also possible.

A frequency other than UHF may be used as the radio frequency of the reader / writer 1.
The rotation of the reflection means 19 may be controlled by a control means other than the reader / writer 1.
The reflection means 19 may have a shape that reflects radio waves in the vertical direction in addition to the horizontal direction, or may be rotationally controlled in the vertical direction in addition to the horizontal direction.
The reflection means 19 may be controlled to swing.

Schematic showing the overall configuration of the first embodiment of the present invention Block diagram schematically showing the electrical configuration of the reader / writer Block diagram schematically showing the electrical configuration of the RFID tag Perspective view of reflection means FIG. 4 equivalent diagram showing a modification FIG. 4 equivalent view showing another modified example FIG. 4 equivalent view showing another modified example FIG. 4 is a view corresponding to FIG. 4, showing the reflecting means in the second embodiment of the present invention. Flow chart showing rotation control operation for reflecting means by reader / writer FIG. 4 equivalent diagram showing a modification FIG. 1 equivalent view showing a modification FIG. 1 equivalent view showing another modification FIG. 1 equivalent view showing another modification FIG. 1 equivalent view showing another modification FIG. 1 equivalent view showing another modification FIG. 1 equivalent view showing another modification

Explanation of symbols

  In the drawings, 1 is a reader / writer (control means), 2 is a transmission antenna, 3 is a reception antenna, 4 is a carriage, 5 is an RFID tag, 19 is reflection means, and 19a is a reflection surface.

Claims (11)

An RFID tag attached to the article;
A reader / writer capable of communicating by transmitting and receiving radio waves to and from the RFID tag;
A reflection means capable of reflecting radio waves transmitted from the reader / writer,
An RFID tag system that enables communication between the RFID tag and the reader / writer by causing the RFID tag to receive radio waves reflected by the reflecting means.
The RFID tag system, wherein the reflecting means has a reflecting surface protruding toward the reader / writer. An RFID tag attached to the article;
A reader / writer capable of communicating by transmitting and receiving radio waves to and from the RFID tag;
A reflection means capable of reflecting radio waves transmitted from the reader / writer,
An RFID tag system that enables communication between the RFID tag and the reader / writer by causing the RFID tag to receive radio waves reflected by the reflecting means.
Control means for controlling the rotation of the reflecting means;
An RFID tag system, wherein a reflection direction of a radio wave transmitted from the reader / writer is changed according to control of the reflection means by the control means.   3. The RFID tag system according to claim 2, wherein the control unit performs rotation control in synchronization with the reader / writer accessing the RFID tag and terminating communication.   4. The RFID tag system according to claim 1, wherein the reflecting means has a semi-cylindrical reflecting surface.   The RFID tag system according to any one of claims 1 to 3, wherein the reflecting means includes a plurality of reflecting portions having different reflection directions.   The reflector is configured by a reflector formed in a parabolic shape, and is installed or rotated so that a reflection direction of a radio wave of the reflector faces a central part of an antenna of the reader / writer. Item 6. The RFID tag system according to Item 5. The antenna is composed of a transmission antenna and a reception antenna,
The reflector is composed of a plurality of parabolic reflectors, and about half of the reflectors face the center of the transmitting antenna, and the remaining reflectors face the center of the receiving antenna. The RFID tag system according to claim 6, wherein the RFID tag system is controlled or rotated.   The RFID tag system according to any one of claims 1 to 7, wherein the reflecting means is formed long in a height direction.   9. The RFID tag system according to claim 8, wherein the reflecting means has a polygonal reflecting surface.   10. The RFID tag system according to claim 9, wherein the control means controls the reflection means to rotate stepwise in synchronization with the reader / writer accessing the RFID tag and terminating communication.   11. The RFID tag system according to claim 2, wherein the control means constitutes a part of the reader / writer.

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