JP2002176312A - Rfid recognition system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inexpensive system capable of reducing a read failure of a RFID by a reader/writer. SOLUTION: A first antenna 10 and a second antenna 11 are arranged while the loop faces of the first and second antennas 10 and 11 do not face each other parallelly but are arranged almost at a right angle to each other. The direction of the line of magnetic force is made different at each point because the line of magnetic force from the first antenna 10 is bent by the magnetic field of the second antenna 11. Even though the RFID passes through between both antennas 10 and 11 with any attitude, the line of magnetic force by the antennas 10 and 11 acrosses the internal antenna of the RFID at a certain position, and power is thereby fed to the RFID to make the antenna 10 communicate with the antenna 11.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an RFID (Radio
The present invention relates to an RFID recognition system that transmits or receives data to / from a frequency identification (RFID) system.

[0002]

2. Description of the Related Art In recent years, RFID has been widely used as a substitute for data carrier means such as bar codes. RFI
D is equipped with an IC chip including a memory for storing data and a simple processor, and a loop antenna for communication, and is attached to an article formed in a portable card size such as a credit card or an article. Various shapes are provided depending on the application, such as those formed as small tags. RFID is a reader
Communication is performed with an antenna of a communication device called a writer based on the principle of electromagnetic induction, and processing such as sending stored data to a reader / writer or storing data transmitted from the reader / writer is performed. Depending on the communication distance and the frequency band used, such RFIDs and reader / writers can be of the contact type (usually battery-less, communication distance of about several millimeters), the proximity type (usually battery-less, communication distance of about 20-30 cm), or the near type. Type (usually without batteries, communication distance about 70-100 cm) and microwave type (usually with batteries, communication distance about several meters). A batteryless RFID operates using a communication radio wave supplied from an antenna of a reader / writer as a power supply. In recent years, in RFID systems, multi-read,
That is, a function of simultaneously reading a plurality of RFIDs has been put to practical use.

In an entry / exit management system using an RFID, a proximity type or a proximity type is used among RFID types. In this type of system, a reading unit provided with an antenna of a reader / writer is provided on a wall surface near an entrance door of a room, and a user holds his / her RFID card over the reading unit, thereby holding information of the RFID, that is, Sends personal ID information etc. to the reader / writer side. The door is opened only when the ID information indicates that entry into the room is permitted.

[0004] A system using RFID for automatic lending management of books is also known. In this system, an RFID tag is attached to each book, and for example, a reader / writer is provided at a lending counter. Then, the user holds the book he / she wants to borrow over the reading surface of the reader / writer, thereby transmitting the book ID information held by the RFID of the book to the reader / writer side, and the lending management system allows the lending of the book. Perform processing.

[0005]

In a system using RFID as described above, generally, the RFID is brought close to the reader / writer, and the RFID card / tag is held up so as to be substantially parallel to the reading surface of the reader / writer. Is required. This is because the loop of the built-in loop antenna of the RFID faces the loop of the antenna of the reading unit from the front (the antenna surfaces are parallel to each other), thereby improving the efficiency of transmission of power and data signals by electromagnetic induction. .

However, the user may find it cumbersome to bring the RFID (or the article on which it is mounted) close to the reader / writer and hold it in a specific posture.

On the other hand, in recent years, the present applicant has provided a reader / writer having a relatively large communication range, such as a proximity type, at the entrance of a facility, so that a user holding an RFID card or an article with an RFID attached thereto can use the reader / writer. RFID just by passing through the doorway
And a system that reads information of the user and executes a rental process and other registration processes. In this system, a user goes to a rental counter or the like to read articles
Work such as holding over a writer is unnecessary. However, even with this system, when the user passes through the doorway,
If the surface of the RFID loop antenna of the user or the article becomes parallel to the line of magnetic force coming out of the reader / writer antenna, the RFID may not be recognized. It is considered that this is because the number of lines of magnetic force crossing the loop of the RFID antenna decreases and the power supplied to the RFID decreases.

The present invention has been made in view of such a problem, and provides an inexpensive system that can reduce a reading failure of an RFID by a reader / writer in an automatic recognition apparatus using a batteryless RFID. The purpose is to:

[0009]

In order to achieve the above object, an RFID recognition system according to the present invention comprises a first loop antenna, a second loop antenna, and an interrogation wave driven by driving the first and second loop antennas. And a controller for extracting data from a response wave from the RFID received by each of the loop antennas.
The first and second loop antennas are disposed on both sides of a pass area through which a recognition target holding an RFID passes, with the respective antenna surfaces being arranged substantially perpendicular to each other. .

The RFID recognition system according to the present invention is arranged such that a wall-like member for regulating a traveling direction when a user carrying an RFID enters a room is sandwiched between the traveling direction regulated by the wall-like member. A pair of loop antennas,
The pair of loop antennas are driven to transmit an interrogation wave, and the RFIDs received by the loop antennas are transmitted.
And a controller for extracting data from a response wave from the controller, wherein the pair of loop antennas are arranged so as to generate lines of magnetic force oblique to the traveling direction.

Further, the RFID recognition system according to the present invention comprises a first and a second loop antenna which are arranged to face each other across a pass area through which a recognition target holding an RFID passes, and the first and the second loop antennas. A controller that drives a two-loop antenna to transmit an interrogation wave and extracts data from a response wave from the RFID received by each of the loop antennas, the first loop antenna and the second loop antenna , Are configured such that the directions of the magnetic fields generated by them are opposite to each other.

[0012]

[First Embodiment] In this embodiment, an entry / exit management system will be described as an example.

[0013] Since a general entry / exit management system at present aims to guarantee strict security, at the time of entering a room, the RFID reader is individually held over the reader to perform personal authentication, and the authentication is successful. However, there are many mechanisms that only allow the door to be opened for a single person to pass. This means that when a particular user is authorized and entered,
This is to prevent people who enter the room continuously or side by side as much as possible.

[0014] However, in a general business establishment, a high degree of security is required in a specific room, and when entering a normal room or passing through the main gate of an office, the employee is merely an employee. Often just check.
In such a case, it is considered that the only requirement imposed on the employee is to have an RFID card that is an employee ID card.
Also, in evacuation drills for fires and the like, if an employee only needs to pass through a certain place and can recognize who the employee is, it is possible to reduce wasted time such as a long roll call.

For this purpose, a system is effective in which a reader / writer is installed at an entrance gate of a business office, at an entrance of each building, or at other check points to read the RFID of passers-by.

In order to realize such a mechanism using a nearby RFID system, first, as one method,
It is conceivable to use a single antenna reader / writer having a long communication distance. However, in this case, the user does not know the maximum communication area of the antenna, and therefore, some persons may unintentionally slip through the check point. The next conceivable thing is that an antenna system in which a dual (that is, a pair) antenna is arranged with its loops facing each other across a passage at a check point, the pair of antennas are operated in synchronization, and a user passes between the antennas. Can be considered.
In this antenna system, a stronger magnetic field is generated and the communication distance is longer than in the case of a single antenna.
The ability to communicate with the FID increases.

However, an employee ID card with a built-in RFID is
There are various forms, such as a simple card form, a form that is clipped in a breast pocket or the like, a necklace type that hangs from the neck with a chain or the like, and how each person carries the RFID. Various. For this reason, when the RFID passes the check point, the relative attitude with respect to the reader / writer also varies. Therefore, the direction of the antenna surface of the RFID card (that is, the surface on which the loop is formed) may be perpendicular to the antenna surface of the reader / writer. in this case,
The number of magnetic fluxes penetrating the inside of the small antenna with built-in RFID is practically eliminated, so that no response wave can be transmitted without generating an electromotive force, and the reader / writer cannot detect the RFID card. This problem is due to the relationship between the orientation of the RFID antenna and the reader / writer antenna, and it is sufficient to simply make the reader / writer antenna system a pair antenna system and make the transmitted radio wave powerful enough. Not be.

This embodiment proposes an apparatus for solving this problem. FIG. 1 shows a schematic configuration diagram of a reader / writer system of the present embodiment. Also in the present embodiment, a pair of antennas that operate synchronously (hereinafter, referred to as dual antennas).
Prepare Here, it is assumed that the dual antennas are so-called loop antennas (large coils), and the diameters of both are different. In the example of FIG. 1, the dual antenna includes a first antenna 10 and a second antenna 11.

For the following explanation, an antenna coordinate system is set for each of the first antenna 10 and the second antenna 11 constituting the dual antenna with reference to the antennas. The antenna coordinate system will be described with reference to FIG. The antenna coordinate system of each antenna 15 is configured such that the center of the loop of the antenna 15 is defined as an origin O, and an axis extending from the origin in the antenna surface 15 (that is, a plane including the loop) in parallel to the ground or the floor is an x-axis. An axis extending perpendicularly to the ground or floor from the origin in the antenna plane is defined as the y-axis. For convenience, the direction going upward in the vertical direction is defined as the positive direction of the y-axis. An axis extending perpendicularly to the x and y axes from the origin O is an axis perpendicular to the antenna surface, which is referred to as a z axis. As for the z-axis, for example, the direction of the front of the antenna is defined as a positive direction. here,
The front surface of the antenna is a direction perpendicular to the antenna surface on a side where a person carrying an RFID card or an article to which an RFID tag is attached has a passage.

In the prior art, the dual antennas are arranged with their antenna planes parallel to each other. In contrast, in the present embodiment, one antenna plane is perpendicular to the other antenna plane. Deploy. In this case, various variations can be considered in the relative arrangement relationship of the second antenna 11 with respect to the first antenna 10, but as a result of an experiment conducted by the inventor, the following arrangement relationship was found to be good.

That is, a good antenna arrangement is such that the antenna surface of the second antenna 11 coincides with the yz-axis plane of the first antenna 10 as shown in FIG. The passage area through which a person or an article having the RFID passes is basically an area between the first antenna 10 and the second antenna 11 and passes therethrough substantially in the x-axis direction in the coordinate system of the first antenna. Suppose you go. In this case, in the access control system, the first antenna 10 and the second antenna 11
Are provided on both sides of the entrance door or the gate, respectively. It should be noted that a desired effect can be obtained in the lower area of the second antenna 11 up to a certain distance, so that it is not impossible to use the area (for example, when a person passes under the second antenna). ). In this arrangement, the second antenna 11 is arranged on the front side of the first antenna 10 (positive direction of the z-axis of the first antenna).
1 is not arranged so that the origin is on the z-axis of the first antenna coordinate system, but is shifted in the y direction (ie, the vertical direction) therefrom. Experiments have shown that in many cases, the area where the effect of recognizing even when the image is passed in such a posture is obtained is large. This is because if the origin of the second antenna 11 is placed on the z-axis of the first antenna 10, a curved region of the magnetic field will be formed vertically symmetrically, while this is shifted in the y-axis direction. It is considered that the region in which the lines of magnetic force are effectively bent is widely formed upward or downward. y
When displaced upward in the axial direction, a region in which the magnetic field is effectively bent is formed widely below, and when displaced downward in the y-axis, conversely, such a region is formed widely above. When a person passes between the antennas, for example by putting the RFID in a pocket or hanging from the neck, the area where the RFID is likely to be present is more widely covered by the area where the magnetic field is effectively bent. do it.

As described above, it is preferable that the origin of the second antenna 11 is shifted from the z-axis of the first antenna 10 in the y-axis direction.

The extent to which the position of the origin is shifted from the z-axis also depends on the size and shape of the second antenna 11 and the strength (ie, output) of the magnetic field. Of course, the relative size ratio and the output ratio with respect to the first antenna 10 are also important factors. Therefore, in consideration of these factors, the area where the RFID is likely to pass can be covered by the area where the magnetic field is effectively bent. As described above, the first antenna 10 and the second antenna 1
The size, output, arrangement relationship, and the like of No. 1 are determined.

As described above, the antenna surface of the second antenna 11
Although it has been described that an arrangement conforming to the yz plane of the first antenna 10 is preferred, this is not strictly required. Even if the antenna surface of the second antenna 11 is slightly shifted or inclined from the yz plane of the first antenna 10, some effects can be obtained.

Returning to the description of FIG. 1, it is assumed that the first and second antennas 10 and 11 are connected to one controller 12 and operate in synchronization with each other under the control of the controller 12. The controller 12 synchronously drives the first and second antennas 10 and 11 to emit an interrogation wave, receives a response wave from the RFID in response to the interrogation wave, and, based on the response wave, data (for example, an ID number) returned by the RFID. Is extracted. The controller 12 is connected to the management computer 14 and sequentially transmits data received from the RFID to the management computer 14. The management computer 14 uses the data obtained from the controller 12
The next operation is determined with reference to the information in the storage device 13. The storage device 13 stores, for example, ID numbers of registered users. In this case, for example, by comparing the ID number received from the RFID with that of each registered user stored in the storage device 13, it can be determined whether the person having the RFID is a registered user. . The management computer 14 processes the data obtained from the controller 12 by instructing the controller 12 to drive the respective antennas and transmit the interrogation wave, or by processing the data stored in the storage device by the data obtained from the controller 12. There are various things such as processing to update,
The processing itself of such received data is publicly known, and thus description thereof is omitted.

According to the experiment, in the antenna arrangement described above, about one third of the area corresponding to the area between the antennas of the conventional dual antenna in which the two loop antennas are opposed to each other in parallel, The desired effect of was confirmed. Of course, in the conventional dual antenna configuration, the area where the above-described desired effect is obtained is substantially zero. In addition,
In order to increase the area where the desired effect can be obtained, it is considered that the size of both antennas may be increased or the driving power of the antennas may be increased.

Next, the antenna arrangement of the present embodiment provides the above-described effective area, that is, an area in which adjacent magnetic field lines are not substantially parallel in any three-dimensional directions. The reason will be described. Here, for the sake of simplicity, the second antenna 1
The description will be made assuming that the origin of 1 is on the z-axis of the first antenna 10. The diameter of the second antenna 11 is assumed to be sufficiently smaller than the diameter of the first antenna 10. In this way, the antennas and the magnetic field formed by the antennas are symmetrical in the left, right, up, and down directions, which makes it easier to explain the phenomenon. (However, as described above, the effective configuration of the actual device is such a symmetrical configuration. Is not limited, RFID assumed
In many cases, it is better to displace the symmetrical position in consideration of the passage area. ).

FIG. 3 shows the state of the magnetic field at a certain moment on the plane including the antenna surface of the second antenna 11 in such a dual antenna arrangement configuration by the distribution of the magnetic force lines 30. It should be noted that the distribution of the lines of magnetic force in this figure and the following figures is conceptual only, and highlights the characteristics of the distribution of the lines of magnetic force that can be actually formed. This figure is a diagram of the antenna structure viewed from the front in the x-axis direction of the coordinate system of the first antenna 10. This direction is almost equal to the direction in which the person carrying the RFID passes between the antennas. The positional relationships of “front”, “center”, and “back” used in the following description are based on this line of sight.

As can be seen from the example of FIG. 3, in the antenna configuration of this embodiment, the front center (that is, the second antenna 1
1), there is almost no portion where the lines of magnetic force 30 are parallel. That is, at a certain fixed x-coordinate value (here, the x-coordinate value of the plane including the second antenna), the direction of the magnetic force lines 30 changes continuously according to the y-coordinate value or the z-coordinate value.

If the second antenna 11 is not provided, the magnetic force lines 30 from the first antenna 10 emerge so that the petals spread in a fan shape as shown in FIG. If provided, the second antenna 11
Due to the magnetic field arising from it. In particular, the magnetic lines of force exiting from the center of the first antenna 10 are substantially parallel to each other without the second antenna 11, but are bent by the magnetic field when the second antenna 11 is present, and the number of parallel portions is reduced. Or it is gone.

On the other hand, there is no obstacle obstructing the direction of the magnetic field lines (ie, the second antenna) at the front and the front, but the magnetic field lines bent at the center (the surface of the second antenna) are pushed toward the front and the back. The lines of magnetic force are slightly bent outward due to the wrinkles caused by the coming (see FIG. 5). But,
The degree of bending of the lines of magnetic force is less than in the center. Therefore, considering the change of the magnetic field lines from the near side to the center (FIGS. 3 and 5), for example, in the coordinate system of the first antenna 10, z
When the coordinate values are fixed, it can be seen that, even if the y-coordinate is the same, if the x-coordinate value is changed, the direction of the line of magnetic force gradually changes in accordance with the change. The same explanation holds for the change in the magnetic field from the front center to the back of the front.

Here, the second antenna 11 is driven in synchronization with the first antenna 10 to generate a magnetic field. In the case of the second antenna 11 alone, a distribution of the magnetic force lines 30 having a shape as shown in FIG. 6 is generated. FIG. 6 is a view of the second antenna 11 as viewed from vertically above. Therefore, the magnetic field generated by the dual antenna system is obtained by superposing the magnetic field of the second antenna 11 on the magnetic field of the first antenna 10. When the first antenna 10 generates magnetic lines of force in the direction as shown in FIG. 4, if both antennas are synchronized so that the second antenna 11 generates magnetic lines of force from the front to the back of FIG. Is integrated into the front (the back of the plane of the second antenna) where the direction of the line of magnetic force of the second antenna 11 matches the flow of the line of magnetic force of the first antenna 10
Are relatively strong at the front, and relatively weak before the front where they are opposite to each other.

When this is illustrated, the magnetic field distribution as shown in FIGS. 7 and 8 is obtained. These figures are views of the dual antenna system of the present embodiment as viewed from a vertical upper cloth.

First, the first antenna 10 and the second antenna 1
On the xz plane that crosses both of the two, as shown in FIG.
Lines of magnetic force exiting from the center of the first antenna 10 are bent outward by a magnetic field exiting from the second antenna 11. On the other hand, in the region above or below the second antenna 11, the influence of the second antenna 11 is smaller than on the xz plane, and therefore, as shown in FIG. It is only slightly bent by the influence of the magnetic field lines bent in the region where the antenna 11 has a strong influence. Therefore, in the coordinate system of the first antenna 10, when a position is moved upward or downward from the center (y = 0) along the y-axis at the same x-coordinate at a certain fixed z-coordinate, the direction of the magnetic field lines thereat It can be understood that changes continuously.

For the reasons described above, in FIG. 9 and FIG. 10, in the specific region surrounded by the first antenna 10 and the broken line 40, the position is changed to any of the x-axis, y-axis, z-axis. It can also be seen that the direction of the lines of magnetic force changes. In addition, as can be seen from FIG. 10, the region has a shape such that a three-dimensional square block can be scraped off by a substantially conical body formed by rotating a parabola or a shape close to the parabola. The closer the x coordinate value is to the origin, the more
The way it is removed (how to dent) is large. Therefore, in this specific area, no matter which direction the RFID is passed in any direction, sufficient magnetic lines of force always pass through the built-in small loop antenna of the RFID, an electromotive force is generated, and a response wave can be sent. As a result, the RFID is recognized.

Next, a specific example of a dual antenna system to which the principle of the present embodiment is applied and experimental results thereof will be described with reference to FIGS. In this example, a system composed of two antennas having a diameter of 45 cm will be described. In this example, as shown in FIG. 11, the origin of the second antenna 81 is not arranged on the z-axis in the coordinate system of the first antenna 10 but is shifted to a position y> 0 (ie, upward). are doing. By doing so, as described above, the area where the desired effect can be obtained increases.

In this example, the offset of the origin of the second antenna 81 from the z-axis (in the coordinate system of the first antenna) is 32.5 cm, as shown in FIG.
The distance from the lower end of 1 to its z-axis is 10 cm. The origin of the second antenna 81 is located at a position 60 cm from the origin of the first antenna 80 in the z-axis direction.

FIGS. 12 and 13 show experimental results when the RFID is placed in a certain posture at each position between the dual antennas. FIG. 12 and FIG. cm until it is in the cm position
Numerical values indicate whether the FID has been recognized.

First, when the RFID card is placed between the first and second antennas in a posture parallel to the antenna surface of the first antenna 80 (that is, a posture in which the surface of the loop antenna of the RFID is parallel to the xy plane), Is in the range of 0 to 35 cm (based on the origin of the first antenna 80),
The RFID could be recognized. It should be noted that this posture can be normally recognized even by a conventional parallel-opposed dual antenna.

Next, FIG. 1 shows an experimental result when the RFID card is in a horizontal (ie, parallel to the ground (floor)) posture.
2 will be described. When the RFID card is in the horizontal posture, its antenna surface is perpendicular to the antenna surface of the first antenna 80, and therefore, the conventional parallel opposed dual antenna could hardly recognize RFID. On the other hand, in the dual antenna structure shown in FIG. 11, RFID could be recognized in a considerable range. FIG.
D is in a horizontal attitude, and the RFID is moved in the z-axis direction at various heights (ie, y coordinate values) on the x = 0 plane (ie, yz plane) in the coordinate system of the first antenna 80.
It indicates the limit of the distance (z-axis direction) at which the RFID can be recognized when moving away from 0. For example, the RFID could recognize up to a distance of 35 cm from the antenna surface of the first antenna 80 at a height of y = 25 cm, and a distance of 30 cm at a height of y = -12.5 cm. In fact, under such conditions, the recognizable distance of the RFID is maximized overall.

Next, FIG. 13 shows the RFID recognition result when the RFID is placed in a posture perpendicular to both the ground surface and the antenna surface of the first antenna 80. This RFI
The D posture is a posture that is likely to occur when, for example, a person puts an RFID card in a breast pocket or hangs a chain from a neck with a chain and passes between antennas. Even in this posture, the surface of the RFID loop antenna is
This is a posture that is difficult to recognize with the conventional dual antenna configuration.

FIG. 13 is also similar to FIG.
This indicates how far away the RFID could be recognized from the device. However, the range in which the RFID is moved is x = −25 cm, that is, yz in FIG.
It is the surface on the near side from the surface. In this example, for example, y = 10
At height from antenna 80 to 35 cm, y = -1
At a height of 2.5 cm, the RFID could be recognized up to 50 cm.

In the case of FIG. 13, the communication recognition distance of the RFID is longer than in the case where the x coordinate shown in FIG. 12 is 0. This can be seen from observing the three-dimensional recognition area of the RFID shown in FIG. In addition, looking at the directions of the magnetic force lines adjacent to each other in FIG. 7, the “front” side is closer to the “center” (the yz plane of the first antenna coordinate system) than the “center” (yz plane).
This can be understood from the fact that they are not parallel. According to this experiment, at least the vertical (up and down) 50 cm and the horizontal (z
It can be seen that within any rectangle of 30 cm (axial), the RFID will be recognizable no matter what direction it passes through in three dimensions. That is, in a three-dimensional area where this rectangle is given a width of 25 cm (x-axis direction), a desired characteristic that RFID in at least a wide range of postures can be recognized can be expected. At a distance of 25 cm, I hate the fact that a walking human suddenly reverses and returns to the original direction, and even if that happens, the RFID will pass through this area even more. Therefore, it can be considered that the recognition probability of the RFID actually increases.

Next, points to be considered when the dual antenna system is applied to an actual entry / exit management system will be described. In the entry / exit management system, for example, the above-described dual antenna system is installed in front of the entrance door. To increase the width of the passage between the two antennas, it is necessary to increase the mutual inductance between the reader / writer antenna and the RFID card antenna by increasing the power supplied to the reader / writer antenna. Then, the user having the RFID card passes through the passage between the antennas (the RFID may be held in any form).
Then, the RFID card is detected by the dual antenna of the reader / writer, and the ID information is read. The management computer opens the door if the read ID information is valid, and does not open the door otherwise. Alternatively, the door may be normally open, and the door may be closed when a valid RFID card is not recognized even though a person trying to pass is detected. In the latter case, it is necessary to separately provide a sensor for detecting approach or passage of a person in addition to the reader / writer.

In the above example, the discussion has been made under the assumption of relatively loose security management, in which a plurality of persons can pass through the door or gate at the same time. It is not limited to such cases. For example, in the configuration of the present embodiment, it is possible to construct a mechanism in which only one person can enter the room without losing the convenience of hands-free by making the door a double structure or adding an infrared sensor.

As described above, according to the antenna configuration of the present embodiment, in an RFID system utilizing electromagnetic induction using a batteryless RFID, the RFID surface is brought close to the vicinity of the antenna and held in a specific direction. There is no need to perform such complicated operations. In the system according to the present embodiment, even if the RFID is freely held or worn without being aware of the orientation, even if the RFID passes through the gate passage where the antenna of the reader / writer is installed, there is almost no problem in reading the RFID. It can be recognized on the writer side.

In the above example, the second antenna 1
Even in a configuration in which a permanent magnet or an electromagnet for generating a constant magnetic field is provided instead of 1, the magnetic field lines of the first antenna 10 can be bent as in the case of the above-described embodiment, so that an effect similar to that of the above-described embodiment can be obtained. .

[Embodiment 2] This embodiment is an example of entry / exit management as in the first embodiment. The first embodiment has a configuration in which large antennas are provided as a pair on both sides of a gate, and a person carrying an RFID passes between them. In this embodiment, a user holds the RFID over a reading unit. . However,
This is a system in which the user does not have to worry about the orientation when holding the RFID as in the related art.

The dual antenna system of the present embodiment is shown in FIG.
As shown in FIG. 4, it is provided in a depression 60 formed in a side wall in front of the entrance door 62. In this case, the two antennas are arranged in a positional relationship as shown in FIG. 1, as in the first embodiment. The two antennas are the RF
The area where the ID can be read in any posture (see the description of the first embodiment) is installed so as to cover the entire depression. With these two antennas, RFID is read by the same mechanism as in the first embodiment. Each antenna is connected to a management computer (not shown) via a controller.
Check whether the D information is valid. The entrance door 62 is controlled by the management computer and allows the person to pass through the door only when valid ID information is detected.

The user can use the RFID 61
Into the recess 60 in the wall. At this time, RFID6
You do not have to worry about the direction of 1.

In a conventional general entry / exit management system using RFID, an antenna embedded in a wall has an RF
Since the recognition is performed with the ID card being parallel, if the RFID card is brought close to the antenna in a nearly perpendicular posture, reading may not be performed in some cases. On the other hand, according to this embodiment, the entry / exit authentication operation can be performed without being conscious of the orientation of the RFID card at all.
In particular, there is an advantage that an elderly person or a person who is vulnerable to a machine can perform an entry / exit procedure without being aware of the direction and direction of inserting a card.

Third Embodiment In the first embodiment, the entry / exit management system is described as an example. However, the dual antenna structure shown in the first embodiment is useful in other applications.

For example, the present invention can be applied to a cash register in a supermarket or other stores. 2. Description of the Related Art In a cash register that has been widely used in recent years, information such as a product number is registered by holding a barcode label attached to a product over a reading unit of a laser reading device provided on a counter. In this method, the clerk needs to hold the product over the reading unit while considering the direction so that the barcode surface can be read by the reading unit.

On the other hand, this embodiment proposes an automatic cash register system including a dual antenna system having the same arrangement as that of the first embodiment. In this system, the dual antenna system is provided on a counter on which a shopping basket is placed. Then, the shopping basket is passed between the dual antennas.

Here, each product, or a box or pallet containing the product, has an RF in which the ID of the product is stored.
The ID is attached.

When the shopping basket passes between the dual antennas, the dual antennas read the RFID of one or more products in the basket, and acquire the ID information of the individual products that the user wants to buy. . If a multi-read reader / writer is used, the R
The FID can be read almost instantaneously. Then, the calculation unit of the register obtains the price of each product from the ID information,
Add them together to get the total price.

Although the attitude of the RFID of the product put in the basket is various, if the dual antenna configuration of the embodiment is used,
Any orientation of RFID can be read.

In the above description, a configuration is shown in which a product is passed between the dual antennas while the product is kept in the shopping basket.
Of course, a store clerk may individually pass each product between antennas. Even in this case, the clerk simply passes between the antennas without worrying about the direction of the product, so that the work load is small.

In the cash register system described above, the dual antenna system composed of two antennas can read the RFID even in almost any posture, and high performance can be obtained with a low-cost and compact device configuration. Can be In addition, in this system, it is possible to quickly detect all the commodities while a large number of commodities are kept in the shopping basket, thereby speeding up the cashier operation.

Fourth Embodiment In the first embodiment, an entry / exit management system is taken as an example. However, the dual antenna structure shown in the first embodiment is useful for other applications. In this embodiment, an example of application to a library book lending / returning management system will be described.

In this example, an RFID tag is attached to each book in the library, and an RFID card is given to each registered library user. Each RFID stores a unique ID information of a book or a user.

Then, the dual antenna system is arranged at the entrance / exit gate of the library with the same arrangement as in the first embodiment. Each antenna is controlled by a reader / writer, and the result of reading by the reader / writer is transmitted to the lending management computer for processing.

In this system, the user can use his / her own RFI
With the D-card on, if the book is passed freely through the entrance / exit gate, the information of the RFID of the user and the book can be read regardless of the respective directions by the dual antenna configuration of the embodiment. Thus, it is possible to detect and register that a book has been lent.

The direction of the RFID of the user and the direction of the RFID of the book when the user passes through the entrance / exit gate are generally various, and the user may set the direction of the RFID card or the book to the predetermined direction and pass through the gate. Forcing the user to increase discomfort and, in turn, reducing the mood of using the library.

On the other hand, according to the present embodiment, the user passes the entrance / exit gate provided with the dual antenna system very naturally, so that the user and the RFID of the book can be recognized, and the book lending process can be performed. Completed virtually instantly. Therefore, the use motivation of the library increases.

[Embodiment 5] Another embodiment of the arrangement of antennas in a reader / writer system will be described with reference to FIG.

In this example, the entrance 110 and the indoor 110
The screen 102 is disposed at a position slightly on the side. The screen 102 is made sufficiently larger than the width of the entrance 100 so that the user who enters through the entrance 100 must turn to the right or left and walk to some extent (for example, about several steps) to enter the room 110. To This allows entrance 100
A user coming from the room must move in the
It will change 0 degrees.

First antenna 103 and second antenna 104
Are arranged at the left and right ends of the screen 102. Here, the first antenna 104 is a partition 102
At the end of the second antenna 104 corresponding to the
It is arranged on the wall 105 on the entrance side in the room. The position of the second antenna 104 is determined by the line extending from the antenna 103 provided on the screen 102 at an inclination of about 45 degrees (based on the traveling direction of the user approaching the entrance 100), and the indoor wall 105. Is the intersection with In this embodiment, the first antenna 103 and the second antenna 104 are provided such that the antenna surfaces are parallel to each other.

When such an entrance structure and antenna configuration are provided, the user generally enters the entrance 102, turns right or left, and straightens or approaches the first antenna 103 and the second antenna 104 as they are. You can expect to pass through. In general, the user carries the RFID card in a breast pocket or hanging it from the neck to the front of the body. In this state, the antenna surface of the built-in antenna of the RFID card is
It is extremely likely that the vehicle is oriented almost perpendicular to the path of the user. Thus, when a user turning right or left on the screen 102 passes between a pair of antennas 103 and 104, the antenna surface of the user's RFID 106 will have the magnetic field lines between those pairs (substantially in the direction of the dashed line shown in the figure). Magnetic flux is not parallel to
An electromotive force is supplied through a built-in antenna 106, and R
A response signal is transmitted from the FID and can be recognized by the reader / writer. Further, when trying to move from the screen to the center of the room, the user changes the traveling direction again, and the possibility that the magnetic flux crosses the RFID antenna surface is further increased. In the experiment, no missed reading of RFID occurred.

At the entrance to a large hall such as a conference room,
It is possible to install such a screen and antenna system. Also, in fact, in recent cinemas, the entrance to the movie screening room has a projection room installed in front of the interior,
In many cases, it is designed so that a spectator can be walked to both sides of the audience, so that such a movie theater can adopt the antenna configuration of this embodiment.

As described above, according to this embodiment, the occupants,
If an RFID is given to a visitor, for example, in the form of a ticket, the ticket can be recognized at the entrance provided in this way, and it is a means to prevent illegal entry.
Note that in the antenna configuration of this embodiment, if the user
It may not be possible to recognize that the FID is held horizontally. However, it is considered that the case of holding a ticket or the like in this manner is extremely rare, and therefore, it is considered that the configuration of this embodiment has practically no problem.

In this embodiment, the first antenna 103 and the second antenna 104 forming a pair are installed so as to be parallel to the wall surface and the screen 102 at an angle of about 45 degrees. Degrees or angles are just examples. However, considering the average in various cases, 45 degrees is considered to be preferable. In principle, the RFID 106
May be arranged at an angle so that the surface of the antenna does not become parallel to the lines of magnetic force between the antennas 103 and 104. Considering the efficiency of electromagnetic induction, the magnetic field lines should be
It is desirable to cross the antenna surface at a nearly vertical angle, but in doing so, the angle between the line connecting both antennas and the wall surface 105 becomes thinner.
The distance between 03 and 104 is extended, leading to the attenuation of the magnetic field. Therefore, it is desirable to determine the arrangement angle of both antennas 103 and 104 in consideration of the trade-off between them.

Embodiment 6 In this embodiment, as shown in FIG. 16, two antennas 110 and 111 are arranged in parallel so as to face each other. These two antennas 11
It is assumed that the user carrying the RFID passes between 0 and 111. FIG. 16 is a diagram of the dual antenna system of the present embodiment as viewed from vertically above.

In this embodiment, the positional relationship between the two antennas is the same as that of the conventional dual antenna system.
However, in this embodiment, the first antenna 110 and the second antenna 111 are driven by signals whose phases are completely reversed.
This includes, for example, the first antenna 110 and the second antenna 1
After synchronizing the respective drive signals to 11, one antenna may be rotated 180 degrees.

FIG. 16 shows the distribution of the lines of magnetic force at a certain moment, which is generated by the dual antennas (110 and 111) driven by the driving signals having the inverted phases. In this distribution, the magnetic fields generated by the antennas driven by the drive signals having the inverted phases are opposite to each other. Therefore, in the area B at the center of both antennas, the magnetic field lines of both antennas cancel each other, and the magnetic field hardly disappears, making it difficult to recognize the RFID. On the other hand, in the area A slightly off the center, , The magnetic field lines are at an angle close to perpendicular to the traveling direction of the user.

Here, it is generally considered that the user puts the RFID in a breast pocket or hangs the neck from the neck to the front of the body. Therefore, the antenna surface of the RFID is used to pass between the antennas. It can be assumed that it is almost perpendicular to the traveling direction of the user (for example, the vertical direction in FIG. 16).

Therefore, when the user enters the area A shown in FIG.
, The magnetic field lines cross the loop antenna of the RFID, and the driving power is supplied to the RFID.
Of course, even if the user passes through a portion slightly shifted left and right from the area A, the magnetic lines of force passing through the RFID antenna surface are secured to a considerable extent. Therefore, according to this configuration, the RFID carried by the user can be practically sufficiently detected.

As described above, according to this embodiment, the RFID
Is held in a posture perpendicular to the traveling direction,
The FID is recognized. In addition, maintaining the RFID in a posture perpendicular to the traveling direction itself is realized in a very natural portable manner, such as putting the RFID card in a breast pocket or hanging it from the neck to the front of the body with a chain. It is not a burden for.

In the above example, the antennas 110 and 1
By inverting the phase of the drive current given to 11,
The directions of the magnetic fields generated by the two antennas are reversed. Alternatively, for example, the winding directions of the loops of the two antennas may be reversed to provide drive signals of the same phase. Can be generated.

Seventh Embodiment In the first embodiment, the antenna surfaces of the first antenna 10 and the second antenna 11 are both perpendicular to the floor (ground) (see FIG. 1). In the case of such an antenna arrangement, when a person carrying the RFID card in a horizontal state passes between the two antennas, the xz plane of the coordinate system of the first antenna (that is, the horizontal plane passing through the center of the first antenna 10). (See FIG. 1 and FIG. 2)) Sensitivity is degraded in the vicinity region (especially, the sensitivity is significantly reduced near the z-axis). This is considered to be because when the RFID card is horizontal, the antenna surface of the RFID is perpendicular to both the antenna surfaces of the first antenna 10 and the second antenna 11. Therefore, in the present embodiment, an antenna arrangement for reducing such sensitivity deterioration will be described.

In this embodiment, basically, the above-mentioned problem of sensitivity deterioration is solved by arranging the second antenna so as not to be perpendicular to the floor.

FIG. 17 shows an example of the antenna arrangement of this embodiment. This example is different from the configuration of the first embodiment in that the second antenna 1
The antenna 30 is rotated around the z-axis, and the antenna surface 131 is arranged so as to be inclined (non-vertical, non-parallel (non-horizontal)) with respect to the floor surface. However, the first antenna 1
The antenna surface 121 of the antenna 20 remains perpendicular to the floor surface, and the relationship that the antenna surface 121 of the first antenna 120 and the antenna surface 131 of the second antenna 130 are substantially perpendicular to each other is also maintained.

FIG. 17 (and FIG. 18 described later)
In this case, the manner of setting the x, y, and z axes for the first antenna 120 is the same as that of the first embodiment (FIG. 2).

According to such a dual antenna arrangement, even if the RFID card passes between the two antennas in a horizontal state, the second antenna 130 is not perpendicular to the RFID antenna, so that the sensitivity is greatly reduced. Be relaxed.

Of course, even in this arrangement, if the RFID antenna surface is perpendicular to both the first antenna surface 121 and the second antenna surface 131, the sensitivity degradation region is formed by the same mechanism as the sensitivity degradation in the first embodiment. Occurs. However, such a sensitivity-deteriorated region is caused by both antenna surfaces 1
Since it is limited to the vicinity of a plane perpendicular to both 21 and 131 (but passing through the center of the first antenna 120), there is no practical problem in this arrangement. This is because the sensitivity degradation area is inclined with respect to the horizontal plane, and the x-axis, which is the direction of passage of the RFID, is not completely included in the area, so that the RFID passes between both antennas in the x-axis direction. This is because, when performing, it always passes through a part outside the sensitivity deterioration area.

This point is different from the arrangement of the first embodiment. In the case of the first embodiment, the passing direction of the RFID card is a direction parallel to the surface of the sensitivity deterioration area (near the xz plane). May not deviate. In this case, there is a possibility that reading (communication) may not be performed if the RFID passes horizontally.

FIG. 18 is another example of the antenna arrangement of the present embodiment, and shows an arrangement in which the antenna surface 141 of the second antenna 140 is parallel to the floor surface (that is, in a horizontal state).

In the case of this arrangement, the sensitivity degradation region is y perpendicular to both the first antenna surface 121 and the second antenna surface 141.
Sensitivity degradation occurs only in the vicinity of the -z plane and only when the antenna surface of the RFID is in the sensitivity degradation area in a state parallel to the yz plane. Therefore, considering that the RFID passes between both antennas in the x-axis direction, the RFID always passes through the area outside the sensitivity degradation area.
Even if the FID is oriented parallel to the worst direction, the yz plane, the sensitivity degradation occurs only while in the sensitivity degradation area, and the RFID can be read in the area before and after the sensitivity degradation area.

As described above, in the present embodiment, the second antenna is arranged so as not to be perpendicular to the floor surface with respect to the first antenna perpendicular to the floor surface. Close to the surface (RFID
It is possible to avoid that the sensitivity degradation region that appears only when the antenna surfaces are parallel) and that the movement path of the RFID moving in the x-axis direction is completely included in the sensitivity degradation region, and reading (communication) error occurs. Can be reduced.

[Brief description of the drawings]

FIG. 1 is a diagram schematically showing an overall system configuration of an embodiment.

FIG. 2 is a diagram for explaining an antenna coordinate system.

FIG. 3 is a diagram conceptually illustrating a state of a magnetic field on a plane including a second antenna in the form of a distribution of magnetic force lines in the dual antenna system of the embodiment.

FIG. 4 is a diagram conceptually showing a state of a magnetic field generated by a first antenna by a distribution of lines of magnetic force when there is no second antenna.

FIG. 5 shows a state of a magnetic field at a position nearer or farther than the second antenna in the dual antenna system of the embodiment.
It is the figure shown notionally in the form of distribution of the line of magnetic force.

FIG. 6 is a diagram conceptually showing a state of magnetic lines of force generated from a second antenna alone.

FIG. 7 is a diagram conceptually showing a state of a magnetic field when the dual antenna system of the embodiment is viewed from vertically above, in the form of a distribution of lines of magnetic force, particularly a state of a magnetic field on a horizontal plane crossing the second antenna. FIG.

FIG. 8 is a diagram conceptually showing a state of a magnetic field when the dual antenna system of the embodiment is viewed from vertically above, in the form of a distribution of lines of magnetic force, particularly in a horizontal plane above or below the second antenna. FIG. 4 is a diagram showing a state of a magnetic field of FIG.

FIG. 9 is a diagram showing an area in which the RFID of any posture can be recognized when the dual antenna system of the embodiment is viewed from the front.

FIG. 10 shows an area where the RFID of any posture can be recognized when the dual antenna is stereoscopically viewed from a general position.
It is a figure shown dimensionally.

FIG. 11 is a diagram illustrating a specific arrangement configuration example of the synchronous dual antenna system according to the embodiment;

FIG. 12 is a diagram for explaining a limit of recognizing the RFID at each position when the RFID is maintained in a horizontal attitude on the ground in the configuration of the synchronous dual antenna of FIG. 11;

FIG. 13 is a diagram for explaining a limit of recognizing the RFID at each position when the RFID is maintained in a posture perpendicular to both the ground surface and the first antenna in the configuration of the synchronous dual antenna of FIG. 11; .

FIG. 14 is a diagram illustrating a system configuration according to a second embodiment.

FIG. 15 is a diagram illustrating a system configuration according to a fifth embodiment.

FIG. 16 is a diagram for explaining a mechanism of a dual antenna according to a sixth embodiment.

FIG. 17 is a diagram illustrating an example of an arrangement configuration of a dual antenna according to a seventh embodiment.

FIG. 18 is a diagram illustrating another example of the configuration of the dual antenna according to the seventh embodiment.

[Explanation of symbols]

10 first antenna, 11 second antenna, 12 controller, 13 storage device, 14 management computer.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H04B 5/02 H04B 5/02

Claims (7)

[Claims] 1. A first loop antenna and a second loop antenna, and the first and second loop antennas are driven to transmit an interrogation wave, and data is obtained from a response wave from the RFID received by each of the loop antennas. A controller for extracting, wherein the first and second loop antennas include an RFID.
An RFID recognition system characterized in that, on both sides of a passage area through which a recognition target holding “1” passes, the antenna surfaces are arranged in an arrangement relationship in which the antenna surfaces are substantially perpendicular to each other. 2. The RFID recognition system according to claim 1, wherein the antenna surface of the second loop antenna is disposed substantially so as to pass through the center of the loop of the first loop antenna. 3. A loop antenna disposed at one end of a pass gate area through which a recognition target holding an RFID passes and facing an effective communication area in the direction of the pass gate area; A controller for transmitting a wave and extracting data from a response wave from the RFID received by the antenna; and a magnetic field generating means disposed near an end of the pass gate area opposite to the loop antenna. RFID recognition system including. 4. A wall-shaped member that regulates the traveling direction when a user carrying an RFID enters a room, a pair of loop antennas disposed with the traveling direction regulated by the wall-shaped member interposed therebetween, A pair of loop antennas are driven to transmit an interrogation wave, and the RFIDs received by the loop antennas are transmitted.
And a controller for extracting data from a response wave from the RFID tag, wherein the pair of loop antennas are disposed so as to generate magnetic lines of force oblique to the traveling direction. system. 5. A first and a second loop antenna disposed opposite to each other with a pass area through which a recognition target holding an RFID passes, and an interrogation wave driven by driving the first and the second loop antennas. And a controller for extracting data from a response wave from the RFID received by each of the loop antennas, and wherein the first loop antenna and the second loop antenna have a direction of a magnetic field generated by each of the first and second loop antennas. An RFID recognition system configured to be opposite to each other. 6. The antenna surface of the first loop antenna is substantially perpendicular to the reference plane parallel to the passing direction of the recognition target holding the RFID, and the antenna surface of the second loop antenna is substantially inclined. The RFID recognition system according to claim 1, wherein the RFID recognition system is arranged so as to be: 7. An antenna surface of the first loop antenna is substantially perpendicular to a reference plane parallel to a passing direction of a recognition target holding the RFID, and an antenna surface of the second loop antenna is substantially parallel. The RFID recognition system according to claim 1, wherein the RFID recognition system is provided.