JP2003283365A - Radio communication system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radio communication system by which scattering of signals can be prevented and the signals can be effectively used. <P>SOLUTION: The RFID system 1 has an interrogator 11, an interrogator antenna 12 which is connected with the interrogator 11 and transmits signals, an approximately elliptic radio wave reflector 14 which reflects the signals emitted from the interrogator antenna 12 and radio tags 13 which receive the signals from the interrogator antenna 12 through at least the approximately elliptic radio wave reflector 14 and respond for performing communication with the interrogator 11. The interrogator antenna 12 is arranged in such a way that the reflecting surface 15 is oriented to a first focal point 16 of the reflecting surface 15 of the approximately elliptic radio wave reflector 14 and the radio tags 13 are arranged in the proximity of a second focal point 17 of the reflecting surface 15 of the approximately elliptic radio wave reflector 14. Since the interrogation signals emitted from the interrogator antenna 12 are reflected by the approximately elliptic radio wave reflector 14 and a region in which the interrogation signals are intensive is formed at the second focal point 17, the communication accuracy of the radio tag 13 positioned at the second focal point 17 with the interrogator 11 is improved. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a wireless communication system for communicating between an interrogator and a responder. In the present invention, "near focus" includes focus.

[0002]

2. Description of the Related Art One of wireless communication systems is a mobile identification (RFID) system. A conventional RFID system is a system having a read / write function and includes an interrogator and a responder. The transponder is called a wireless tag and stores information in accordance with an instruction from the interrogator and transmits the stored information.

As a wireless tag used in an RFID system, particularly in a micro area, a wireless tag having a built-in battery is a factory automation (Factory Automati).
is often used in the field of abbreviated as FA), but due to the progress of semiconductors, that is, the technology of wireless communication circuits using semiconductors, wireless tags that do not have a battery to obtain driving power from a signal based on an interrogator have been developed. It has been developed and is being considered for various uses in many fields. Hereinafter, a wireless tag having no battery may be referred to as a batteryless tag.
An RFID system using a battery-less tag has a simple configuration and can be formed at low cost. Therefore, product management in a production line or warehouse, picking system for automatically sorting items, mail delivery, home delivery, etc. FA, distribution and logistics Applications in a wide range of fields such as fields are being studied.

FIG. 14 is a diagram showing a basic structure of a conventional RFID system 1. RFID system 1
Includes an interrogator 2, an interrogator antenna 3, and a wireless tag 4. The interrogator antenna 3 is connected to the interrogator 2. The wireless tag 4 includes a tag antenna and a tag IC (Integrated Circuit) having a wireless communication function.

The interrogator 2 generates a question, and the interrogator antenna 3 transmits a question signal representing the question to the wireless tag 4. The wireless tag 4 receives the inquiry signal with the tag antenna and transmits the tag I
An answer to the question is generated by C, and a response signal representing the answer is transmitted from the tag antenna. The response signal transmitted from the wireless tag 4 is received by the interrogator antenna 3, and the answer is given to the interrogator 2. As a result, the information held by the wireless tag 4 is taken out. Further, in the RFID system 1, information is transmitted from the interrogator 2 to the wireless tag 4,
Information can be written and stored in the wireless tag 4.

Since the interrogation signal is radiated from the interrogator antenna 4 as radio waves, most of the interrogation signals are scattered as useless radio waves. On the other hand, if the inquiry signal is scattered, the wireless tag 4
In, the power obtained from the interrogation signal transmitted from the interrogator antenna 3, that is, the acquired communication power, becomes smaller as the interrogator antenna 3 moves away from the interrogator antenna 3. Therefore, the smaller the distance between the interrogator antenna 3 and the wireless tag 4, the larger the acquired communication power, so the communication accuracy between the interrogator 2 and the wireless tag 4 becomes high, and the distance between the interrogator antenna 3 and the wireless tag 4 increases. Since the acquired communication power becomes smaller as the value increases, the communication accuracy between the interrogator 2 and the wireless tag 4 decreases.

[0007] The distance between the interrogator antenna 3 and the wireless tag 4, which enables communication between the interrogator 2 and the wireless tag 4, is
The power obtained from the entire signal radiated by the interrogator antenna 3, that is, the radiated communication power, and the signal reception sensitivity of the interrogator 2 and the wireless tag 4 vary, but in the case of an RFID system using a batteryless tag, several cm to The range is about 2 m.

Therefore, in the direction of the interrogator antenna 3, the RFID system 1 is provided with a conveyor such as a belt conveyor for moving an object on which the RFID tag 4 is attached.
Then, in a state where the wireless tag 4 is arranged in a region where the power obtained from the inquiry signal is large, that is, in a region where the distance between the interrogator antenna 3 and the wireless tag 4 is the communicable distance.
Communication is performed between the interrogator 2 and the wireless tag 4.

[0009]

[Problems to be Solved by the Invention] Interrogator 2 and RFID tag 4
In order to improve the communication accuracy with the interrogator 2, it is necessary to widen the arrangement range of the radio tag 4 with respect to the interrogator antenna 3, which is the distance at which the interrogator 2 and the radio tag can communicate.

If the radiated communication power is increased, the communicable distance between the interrogator antenna 3 and the wireless tag 4 can be extended, but the power consumption increases. In order to extend the communication distance without increasing the radiated communication power,
It suffices to eliminate signal scattering and collect signals in a desired area. However, in the RFID system 1, as described above, it is difficult to irradiate the signal transmitted from the interrogator antenna 3 to a desired range, and in particular, the smaller the interrogator antenna 3 is, the wider the directivity is. The interrogation signal that is not effectively radiated to 4 increases and scatters. In addition, the interrogation signal scattered far away is transmitted to another RFID system and a wireless LAN (Local Area Network; abbreviated as LA).
There is also a problem that it becomes an interference wave to a wireless communication system such as N) and adversely affects it.

A technique for suppressing signal scattering is disclosed in Japanese Patent Laid-Open No. Hei 5
JP-A-128289 discloses a system for controlling a phase to concentrate a millimeter wave. Phased array antennas are used in this system. However, the phased array antenna requires a phase shifter connected to each antenna, which complicates the configuration and increases the cost.

It is an object of the present invention to provide a wireless communication system which has a simple structure, prevents signal scattering, and effectively uses signals.

[0013]

SUMMARY OF THE INVENTION The present invention is an interrogator, an interrogator antenna connected to the interrogator for transmitting a signal, and an elliptic curve or similar for reflecting the signal transmitted by the interrogator antenna. A signal from the interrogator antenna and a substantially elliptical radio wave reflection plate formed by a reflecting surface including a part of a curve can be received, and communication can be performed between the interrogator via at least the approximately elliptical radio wave reflection plate. And a transponder.

According to the present invention, the signal transmitted from the interrogator antenna can be reflected by a substantially radio wave reflector having a reflecting surface including a part of an elliptic curve or a curve similar thereto and received by a transponder. it can. By providing the substantially elliptical radio wave reflection plate and reflecting the signal, it is possible to prevent the signal from being transmitted and scattered to the back side of the substantially elliptical radio wave reflection plate, that is, the side opposite to the reflection surface. by this,
It is possible to reduce radio wave interference with other wireless communication systems. Further, the signal can be collected in an area facing the reflecting surface on the reflecting surface side of the substantially elliptical radio wave reflecting plate, and the signal can be effectively used. For example, the transponder can directly receive the signal transmitted from the interrogator antenna, reflect the signal by the substantially elliptical radio wave reflection plate, and use both of them.

Further, since the reflecting surface of the substantially elliptical radio wave reflecting plate is a curved surface, the signal reflected by the reflecting surface can be locally focused in the area facing the reflecting surface of the substantially elliptical radio wave reflecting plate. it can. Therefore, by concentrating the signal transmitted from the interrogator antenna, a strong region of the signal can be easily formed, and by placing the transponder in the strong region of the signal, the gain is improved and the interrogator is increased. The communication accuracy between the interrogator antenna and the transponder can be improved, and the communicable distance between the interrogator antenna and the transponder can be extended.

Further, since the signal transmitted from the interrogator antenna can be reflected by the reflecting surface of the substantially elliptical radio wave reflection plate and guided to the transponder, the propagation direction of the signal can be changed, and the interrogator antenna and the response can be changed. The degree of freedom of arrangement with the vessel is increased.

Further, the present invention is characterized in that the interrogator antenna is arranged in the vicinity of the focal point of one of the reflection surfaces of the substantially elliptical radio wave reflection plate, and is directed to the reflection surface of the substantially elliptical radio wave reflection plate. .

According to the present invention, the signal transmitted from the interrogator antenna disposed near the focal point of one of the reflecting surfaces of the substantially elliptical radio wave reflection plate and directed to the reflecting surface is reflected by the substantially elliptical radio wave reflection plate. After being reflected by the surface, it is focused near the other focus of the reflecting surface of the substantially elliptical radio wave reflection plate. Therefore, an area where the signal transmitted from the interrogating antenna is strong can be easily formed near the other focus.

For example, even if the interrogator antenna has a wide directional characteristic, it is possible to easily form a region in which the signal transmitted from the interrogator antenna is strong in the vicinity of the other focus of the reflecting surface of the substantially elliptical radio wave reflection plate. The communication accuracy between the interrogator and the responder can be improved.

According to the present invention, the interrogator antenna is arranged in the vicinity of an imaginary straight line that includes one of the focal points of the reflecting surfaces of the substantially elliptical radio wave reflecting plate and passes through the reflecting surface, and is substantially parallel to the imaginary straight line. It is characterized by directing the reflection surface of the substantially elliptical radio wave reflection plate.

According to the present invention, the substantially elliptical radio wave reflection plate is disposed in the vicinity of a virtual straight line passing through the reflection surface, including the focal point of one of the reflection surfaces of the substantially elliptical radio wave reflection plate, and substantially parallel to the virtual straight line. The signal transmitted from the interrogator antenna can be reflected by the reflecting surface of the substantially elliptical radio wave reflection plate and focused near the other focus of the reflecting surface of the substantially elliptical radio wave reflection plate by directing the reflecting surface of . Therefore, a strong region of the signal transmitted from the interrogator antenna can be easily formed near the other focus.

For example, even if the interrogator antenna has a wide directional characteristic, it is possible to easily create a region where the signal transmitted from the interrogator antenna is strong in the vicinity of the other focus of the reflecting surface of the substantially elliptical radio wave reflection plate. The communication accuracy with the transponder can be improved. Further, even if the interrogator antenna is not provided near one of the focal points of the reflecting surface of the substantially elliptical radio wave reflection plate, a strong signal region can be formed near the other focal point of the reflecting surface of the substantially elliptical radio wave reflection plate. The interrogator antenna can be arranged at a position where it does not prevent the propagation of signals to and from the transponder and does not hinder communication.

Further, the present invention is characterized in that the reflecting surface of the substantially elliptical radio wave reflection plate is a curved surface including an elliptic curve or a curve similar to the elliptic curve except a portion intersecting a straight line passing through two focal points. .

According to the present invention, the reflecting surface of the substantially elliptical radio wave reflection plate is a curved surface including a part of a curve excluding a portion intersecting a straight line passing through two focal points of an elliptic curve or a similar curve. When the signal transmitted from one of the interrogator antenna and the transponder is reflected by the substantially elliptical reflector and propagates to the other, the interrogator antenna and the transponder do not hinder signal propagation. For example, the interrogator antenna is arranged near one of the focal points on the reflecting surface of the substantially elliptical radio wave reflection plate, and the signal transmitted from the interrogator antenna is focused near the one focal point through the approximately elliptical radio wave reflection plate. Thus, the signal transmitted from the interrogator antenna is not disturbed by the interrogator antenna and the transponder itself when being guided to the transponder located there.

According to the present invention, a plurality of substantially elliptical radio wave reflection plates are provided, and each of the substantially elliptical radio wave reflection plates is arranged so that at least one focal point coincides with a focal point of the reflection surface of another approximately elliptical radio wave reflection plate. It is characterized by

According to the present invention, the plurality of substantially elliptical radio wave reflection plates are arranged such that at least one focal point of the reflection surfaces coincides with the focal points of the reflection surfaces of the other substantially elliptical radio wave reflection plates. In this case, in two substantially elliptical radio wave reflection plates whose focal points match,
The signal reflected by one of the substantially elliptical radio wave reflection plates through one of the focal points of one of the approximately elliptical radio wave reflection plates is reflected, and then is reflected at the other focal point of the one of the substantially elliptical radio wave reflection plates, and It passes through one focal point of the substantially elliptical radio wave reflection plate and focuses on the other focal point of the other substantially elliptical radio wave reflection plate. Therefore, a strong signal region is formed near the focal point of each substantially elliptical radio wave reflection plate. Therefore, it is possible to widen the area where the signal is strong, and it is possible to increase the communicable distance between the interrogator antenna and the transponder by providing the substantially elliptical radio wave reflection plates as described above.

Further, the present invention has a plurality of interrogator antennas connected to the interrogator, wherein a transponder receives a signal transmitted from one interrogator antenna, and other signals are transmitted from the transponder. The interrogator antenna is used for reception.

According to the present invention, since the interrogator antenna for transmitting a signal to the transponder and the interrogator antenna for receiving the signal from the transponder are individually provided, transmission / reception with the transponder can be performed by one interrogator antenna. Since it is not necessary to process the received signal from the transponder in consideration of the fact that the signal sent from the interrogator to the interrogator antenna is reflected by the interrogator antenna connected to the interrogator itself as in the case of performing, Processing of the received signal from the transponder becomes easy.

Further, the present invention is characterized in that the transponder is arranged in the vicinity of the other focus of the reflecting surface of the substantially elliptical radio wave reflecting plate.

According to the present invention, the transponder efficiently arranges the signal transmitted from the interrogator antenna by disposing the transponder in the strong signal region near the other focal point of the reflecting surface of the substantially elliptical radio wave reflection plate. Since it can be received, the communication accuracy between the interrogator and the responder is improved.

Further, the present invention is characterized in that the reflecting surface of the substantially elliptical radio wave reflecting plate includes a part of a spheroidal surface, an elliptic cylindrical surface or a curved surface similar thereto.

According to the present invention, the reflecting surface of the substantially elliptical radio wave reflection plate is formed to include a part of a spheroidal surface, an elliptic cylindrical surface, or a curved surface similar thereto. A spheroidal surface is a curved surface formed by rotating an ellipse around a major axis or a minor axis, and an elliptic cylindrical surface is formed by a locus that slides the ellipse in a direction intersecting its major axis and minor axis. Is a curved surface. Therefore, the signal transmitted from the interrogator antenna and reflected by the reflection surface of the reflector of the elliptical radio wave reflector is
It can be focused efficiently.

Further, the present invention has a plurality of interrogator antennas connected to the interrogator, and each interrogator antenna has a signal transmitted from each of the interrogator antennas reflected by a substantially elliptical radio wave reflection plate. After that, they are arranged so as to be focused on different regions.

According to the present invention, the plurality of interrogator antennas connected to the interrogator are arranged so that the signals transmitted from the interrogator antennas are reflected by the reflecting surface of the substantially elliptical radio wave reflection plate and are focused on different areas. They can be arranged, a strong signal region can be widely provided, and a communication range with high communication accuracy between the interrogator and the responder can be expanded.

Further, the present invention is characterized in that communication is performed between the interrogator and the moving responder while moving the responder.

According to the present invention, by moving the transponder and performing communication between the interrogator and the moving transponder, the transponder can widely pass through a strong signal region, and the interrogator can: It is possible to communicate with different transponders one after another.

In the present invention, the interrogator has a transmitter for generating a question, and a receiver provided separately from the transmitter for receiving an answer from the responder, and the interrogator antenna is for transmitting. An interrogator antenna for reception and an interrogator antenna for reception are provided, the interrogator antenna for transmission is connected to the transmitter, and the interrogator antenna for reception is connected to the receiver.

According to the present invention, the transmitting interrogator antenna is connected to the transmitter that generates the question, and the receiving interrogator antenna is connected to the receiver, so that the transmitting interrogator antenna and the receiving interrogator antenna are connected. It is possible to dispose and away from each other, which increases the degree of freedom of arrangement. Further, in this case, a path such as a connection line between each antenna and the transmitter and the receiver can be shortened, and the influence of the path such as the connection line on a signal can be reduced.

Further, in the present invention, the transponder comprises a processing circuit having at least a modulator and a memory for accumulating information, and an antenna for transmitting and receiving a signal, and the processing circuit comprises:
When a signal is received by the antenna, based on that signal,
It is characterized in that the signal reflected by the antenna is reflected by changing the reflection characteristic of the antenna in the modulator using the signal related to the information stored in the memory.

According to the present invention, when the transponder receives the signal transmitted from the interrogator antenna, the transponder receives a signal related to the information stored in the memory unit based on the signal from the interrogator received by the processing circuit. The information stored in the memory unit can be read by the interrogator by changing the reflection characteristic of the antenna in the modulation unit by using and to reflect the signal received by the antenna. For example, information about the object to which the transponder is attached can be read using the interrogator.

In the present invention, the transponder comprises at least a demodulation section and a processing circuit having a memory section for accumulating information, and an antenna for receiving a signal. The processing circuit, when the signal is received by the antenna, It is characterized in that information is written in the memory portion based on the signal.

According to the present invention, when the transponder receives the signal transmitted from the interrogator antenna by the antenna, the transponder demodulates the signal from the interrogator received by the processing circuit in the demodulator and writes the signal in the memory. Thus, the information can be given from the interrogator and the information can be stored in the memory unit. For example, information about the object to which the transponder is attached can be transmitted and written from the interrogator.

Further, the present invention has a non-ellipsoidal radio wave reflector formed by a reflecting surface having a shape different from the shape including a part of an elliptic curve or a curve similar to the elliptic curve, and the transponder has at least a substantially elliptic wave. It is characterized in that communication with the interrogator is possible via the reflector and the non-ellipsoidal radio wave reflector.

According to the present invention, the signal reflected by the reflecting surface of the substantially elliptical radio wave reflection plate can be further reflected by the reflecting surface of the non-ellipsoidal radio wave reflection plate to further effectively use the signal. In particular, when the reflecting surface of the substantially elliptical radio wave reflecting plate and the reflecting surface of the non-elliptical radio wave reflecting plate are arranged so as to face each other, it is possible to prevent signals from being scattered from the region sandwiched by the reflecting surfaces of the plurality of reflecting plates.

The present invention also provides an interrogator, an interrogator antenna connected to the interrogator for transmitting a signal, and an elliptic curve or a part of a curve similar to the elliptic curve for reflecting the signal transmitted by the interrogator antenna. A substantially elliptical radio wave reflection plate formed by a reflection surface including the non-elliptical radio wave reflection plate formed by a reflection surface having a shape different from a shape including a part of an elliptic curve or a curve similar thereto, and the interrogator antenna And a transponder capable of communicating with the interrogator via at least the substantially elliptical radio wave reflection plate and the non-ellipsoidal radio wave reflection plate.

According to the present invention, in the communication between the interrogator and the transponder, the signal transmitted from the interrogator antenna is formed by a reflecting surface including a part of an elliptic curve or a curve similar thereto. It is reflected by the elliptical radio wave reflection plate. Therefore, the signal transmitted from the interrogator antenna and not directly received by the responder is reflected by the reflecting surface of the substantially elliptical radio wave reflection plate,
It can be led to the transponder again. Among the signals reflected by the reflecting surface of the elliptical wave reflector, the signals not received by the transponder are the reflecting surfaces of the non-elliptical wave reflector with a shape different from the shape including a part of the elliptic curve or a curve similar to it. The signal can be effectively used because it can be reflected by and guided to the transponder again. For example, the transponder directly receives the signal transmitted from the interrogator antenna, reflects it by the substantially elliptical radio wave reflection plate, and further receives the signal reflected by the reflection surface of the substantially elliptical radio wave reflection plate. Each signal can be used by receiving the light reflected by the reflecting surface of the plate. Further, in particular, by disposing the reflecting surface of the substantially elliptical radio wave reflecting plate and the reflecting surface of the non-ellipsoidal radio wave reflecting plate so as to face each other, it is possible to prevent signals from being scattered from a region sandwiched by the reflecting surfaces of the plurality of reflecting plates.

Further, since the reflecting surface of the substantially elliptical radio wave reflecting plate is a curved surface, the signal reflected by the reflecting surface can be locally collected in the area facing the reflecting surface of the substantially elliptical radio wave reflecting plate. it can. Therefore, by collecting signals transmitted from either the interrogator antenna or the transponder, a strong region of the signal can be easily formed,
By arranging the other one in the strong signal area, the gain can be improved, the communication accuracy between the interrogator and the responder can be improved, and the distance at which communication between the interrogator antenna and the responder is possible. Can be extended.

Further, since the signal transmitted from the interrogator antenna can be reflected by the reflecting surfaces of the substantially elliptical radio wave reflection plate and the non-ellipsoidal radio wave reflection plate and guided to the responder, the pointing of the interrogator antenna is indirectly performed. The degree of freedom in arranging the interrogator antenna and the responder is increased.

[0049]

BEST MODE FOR CARRYING OUT THE INVENTION A wireless communication system, which is a wireless communication device of the present invention, includes an interrogator, an interrogator antenna connected to the interrogator, and a responder. The interrogator is
A question to the responder is generated, and the interrogator antenna transmits a question signal, which is a signal representing the question, as a radio wave. The responder receives the inquiry signal and performs a response process to the inquiry.
For example, an answer to a question is generated based on the information accumulated in itself, and a response signal, which is a signal representing the answer, is reflected and transmitted as an electric wave. The response signal reflected and transmitted from the transponder is received by the interrogator antenna, and the answer is given to the interrogator. Further, for example, the information based on the question is stored and accumulated. In this way, in the wireless communication system, communication is performed between the interrogator and the responder. INDUSTRIAL APPLICABILITY The present invention can be suitably used particularly for short-distance wireless communication.

Specific examples of the embodiments of the present invention will be described below. FIG. 1 is a diagram showing a configuration of a mobile body identification system (hereinafter referred to as an RFID system) 10 which is a first embodiment of the present invention. An RFID system 10 which is a wireless communication device includes an interrogator 11, an interrogator antenna 12 connected to the interrogator 11, a wireless tag 13 which is a responder, and a substantially elliptical radio wave reflection plate 14. . In FIG. 1, the cross section of the substantially elliptical radio wave reflection plate 14 is shown.

The interrogator 11 is composed of a transmitter that generates a question for the wireless tag 13, a receiver that receives a response from the wireless tag 13, and a signal separator. The signal separator includes a circulator that separates the interrogation signal transmitted from the transmitter to the interrogator antenna 12 and the response signal received by the interrogator antenna 12. The transmission unit is a question generation unit that generates a question signal representing a question such as a response command that is a command for reading information stored in the wireless tag 13 and a write command that is a command for writing information to the wireless tag 13. And a modulator for generating a modulated interrogation signal by modulating the interrogation signal, which is a signal representing an interrogation, with the transmission source. The receiving unit is configured to include a demodulator including a synchronous detector that demodulates the response signal received by the interrogator antenna 12.

The interrogator 11 sends the interrogation signal modulated by the modulator to the interrogator antenna 12, receives the signal received by the interrogator antenna 12 from the interrogator antenna 12, demodulates it by the demodulator, and returns the answer. Is configured to get.

The interrogator antenna 12 has, for example, two dipole antennas orthogonal to each other and a phase shifter,
Interrogation signals are provided from the phase shifters to the dipole antennas with a phase difference of 90 degrees from each other, whereby the interrogation signals can be circularly polarized and transmitted. Further, the interrogator antenna 12 converts signals having a phase difference of 90 degrees obtained from the dipole antennas into signals having no phase difference by a phase shifter and combines the signals. The interrogator antenna 12 can receive both the response signal reflected and transmitted in the linearly polarized wave or the response signal reflected and transmitted in the circularly polarized wave from the wireless tag 13.

In the present embodiment, the interrogator 11 and the interrogator antenna 12 are provided separately, but the interrogator 11 and the interrogator antenna 12 may be integrated as another embodiment of the present invention. . Further, as still another embodiment of the present invention, the interrogator antenna 12 may be a normal circular polarization antenna such as a plane antenna or a linear polarization antenna.

The substantially elliptical radio wave reflection plate 14 is a reflection plate having a reflection surface 15 for reflecting a radio wave signal. The reflecting surface 15 of the substantially elliptical radio wave reflection plate 14 is a concave surface that curves inward, and is a curved surface including a part of a spheroidal surface, an elliptic cylindrical surface, or a surface similar to the spheroidal surface. It is a curved surface composed of parts. A spheroid is a curved surface formed by rotating an ellipse around the major or minor axis of the ellipse, and an elliptic cylindrical surface is defined by the locus of sliding the ellipse in the direction intersecting its major and minor axes. It is a curved surface that is formed. A curved surface including a part of a spheroidal surface, an elliptic cylindrical surface, or a curved surface similar to these includes an elliptic curve or a part of a similar curve.

The reflecting surface 15 of the substantially elliptical radio wave reflecting plate 14 is, for example, an elliptic cylindrical surface including only one of two intersections with the major axis of the ellipse, or a rotating ellipsoid.

The substantially elliptical radio wave reflection plate 14 can reflect the inquiry signal transmitted from the interrogator antenna 12 and the response signal reflected and transmitted from the wireless tag 13 on the reflection surface 15.

The interrogator antenna 12 is arranged near one focus of the reflecting surface 15 of the substantially elliptical radio wave reflection plate 14, and is arranged at one focus in the present embodiment. Here, the focus of the reflecting surface 15 of the substantially elliptical radio wave reflecting plate 14 is a position at which the ellipse defining the reflecting surface 15 of the substantially elliptical radio wave reflecting plate 14 becomes a focus, and in the case of a spheroidal surface, the axis line is set. It shows the set of focal points of an elliptic curve when cut along the plane containing it, and in the case of an elliptic cylindrical surface, it shows the set of focal points of an elliptic curve when cut along a plane perpendicular to the axis of the elliptic cylindrical surface. When the reflecting surface of the reflecting plate 14 is a spheroidal surface or an elliptic cylindrical surface, it indicates the focus of the spheroidal surface or the elliptic cylindrical surface that approximates these surfaces. The vicinity of the focal point includes the focal point and the area around the focal point, and an area in which a signal transmitted so as to pass through one of the focal points can be accurately processed by receiving in the vicinity of the other focal point. Is.

In this embodiment, the interrogator antenna 12 is used.
Is arranged at a first focus 16 which is one of the two focal points of the substantially elliptical radio wave reflection plate 14, and is directed toward the second focal point 17 which is the other focus and the substantially elliptical radio wave reflection plate 14. Will be placed.

2 and 3 are plan views of the substantially elliptical radio wave reflection plate 14 viewed from the first focus 16. The substantially elliptical radio wave reflection plate 14 may be formed to have an elliptical shape as shown in FIG. 2 when viewed from the first focus 16, and FIG.
As shown in, it may be formed in a rectangular shape.

4 and 5 are diagrams showing a typical example of the wireless tag 13, FIG. 4 is a plan view of the first wireless tag 13a which mainly transmits and receives a linearly polarized signal, and FIG. It is a top view of the 2nd wireless tag 13b which transmits and receives a circular polarization signal. In the present embodiment, as the wireless tag 13, a batteryless tag that does not have a battery and that obtains driving power from an inquiry signal transmitted from the interrogator antenna 12 is shown.

The first RFID tag 13a shown in FIG. 4 has a dipole antenna 19 as a tag antenna and a tag IC (Integr) as a processing circuit on a flat dielectric substrate 18.
atedCircuit) 20. The tag IC 20 is realized by a semiconductor integrated circuit, and has a demodulation unit, a modulation unit, and a memory unit that stores information. Dipole antenna 1
When the question obtained by demodulating the question signal received at 9 in the demodulation section is a response command, the modulation section changes the reflection characteristic of the dipole antenna 19 using the signal related to the information stored in the memory section, and the dipole antenna is changed. A part of the inquiry signal is modulated into a response signal representing an answer by 19 and reflected and transmitted. On the other hand, if the question obtained by demodulating the question signal received by the dipole antenna 19 by the demodulator is a write command,
The received information is written in the memory section. In the present embodiment, the tag IC 20 is configured to have the function corresponding to both the response command and the write command, but as still another embodiment of the present invention, the tag IC 20 has only the function corresponding to the response command. It may be configured to have. In still another embodiment of the present invention, when the question obtained by demodulating the question signal received by the dipole antenna 19 by the demodulation section is a response instruction, the tag IC 20 stores it in the memory section based on the instruction. Signals related to the information
The configuration may be such that the dipole antenna 19 is controlled so that the dipole antenna 19 transmits a response signal that is modulated by the modulator and represents a response.

The second wireless tag 13b shown in FIG.
It includes a dipole antenna 22 arranged orthogonal to one surface of a flat dielectric substrate 21, a phase adjusting circuit, and a tag IC 20 which is a processing circuit. Second wireless tag 1
3b is provided with orthogonal dipole antennas 22 and has a phase difference, so that circularly polarized waves can be efficiently transmitted and received. In addition, the second wireless tag 13b can transmit and receive right-handed circular polarization and left-handed circular polarization.

Although depending on the gain of the interrogator antenna 12 and its radiated communication power, the wireless tag 13 is
Is widely arranged in the first region A in the vicinity of and the second region B in the vicinity of the second focus 17 of the reflecting surface 15 of the substantially elliptical radio wave reflection plate 14. The wireless tag 13 can directly communicate with the interrogator 11, and can indirectly communicate with the interrogator 11 via the reflecting surface 15 of the substantially elliptical radio wave reflection plate 14.

When the interrogator antenna 12 transmits the interrogation signal, the RFID tag 13 arranged in the first area A near the interrogator antenna 12 has sufficient acquired communication power obtained from the interrogation signal. Is supplied to. Therefore, the communication between the wireless tag 13 arranged in the first area A and the interrogator 11 is performed accurately.

On the other hand, in the interrogation signal transmitted from the interrogator antenna 12, the first area A in the vicinity of the interrogator antenna 12
The inquiry signal that is not received by the wireless tag 13 arranged in the direction is directed to the substantially elliptical radio wave reflection plate 14. Interrogator antenna 1
The power of the interrogation signal transmitted from 2 is the interrogator antenna 1
The smaller the distance from 2, the smaller is the acquired communication power obtained directly from the interrogator antenna 12 by the wireless tag 13 arranged in the second area B. However, the inquiry signal directed to the substantially elliptical radio wave reflection plate 14 is
The light is reflected by the reflection surface 15 of the second focus 17 and is focused intensively on the second focus 17 and the third region C in the immediate vicinity of the second focus 17.
Therefore, in the third region C, the power density is increased and a region where the interrogation signal is strong is formed. In the area where the inquiry signal is strong, the acquired communication power of the wireless tag 13 is large. Therefore, the communication accuracy between the wireless tag 13 and the interrogator 11 arranged in the third area C, which is an area where the inquiry signal is strong, becomes high.

The response signal that is modulated and reflected by the wireless tag 13 and transmitted is received by the interrogator antenna 12 directly or through the reflecting surface 15 of the substantially elliptical radio wave reflecting plate 14.
The distance between the first focus 16 and the second focus 17 is
The distance is suitable for the RFID system 10.

Either the first wireless tag 13a or the second wireless tag 13b described above may be used as the wireless tag 13, but when communication is performed using circular polarization, the wireless tag 13 shown in FIG. By using the second wireless tag 13b, efficient communication can be performed. Second wireless tag 13b
Can correspond to right-handed circularly polarized wave on one side and can correspond to left-handed circularly polarized wave on the other side. For example, when the interrogator antenna 12 transmits an interrogation signal with right-handed circular polarization, the interrogator antenna 1
By arranging one side of the second wireless tag 13b, which is arranged near the interrogator antenna 12 and directly communicates with the interrogator antenna 12, so as to face the interrogator antenna 12, efficient reception can be performed. Further, in this case, the inquiry signal reflected by the reflecting surface 15 of the substantially elliptical radio wave reflection plate 14 becomes a left-handed circularly polarized wave and is focused on the third region C. Second placed in the third area C
By arranging the other surface of the wireless tag 13b so as to face the substantially elliptical radio wave reflection plate 14, efficient reception can be performed. The response signal reflected and transmitted from the wireless tag 13 arranged in the third area C toward the substantially elliptical radio wave reflection plate 14 is:
Left-handed circularly polarized wave, but the reflection surface 1 of the substantially elliptical radio wave reflection plate 14
By being reflected at 5, it becomes a right-handed circularly polarized wave and can be received by the interrogator antenna 12.

As described above, in the RFID system 10,
The RFID tag 1 arranged near the interrogator antenna 12 by the interrogation signal transmitted from the interrogator antenna 12 arranged at the first focal point 16 of the reflecting surface 15 of the substantially elliptical radio wave reflection plate 14.
Signals that are not received at 3 are reflected by the reflection surface 15 of the substantially elliptical radio wave reflection plate 14, and are reflected by the reflection surface 15 of the substantially elliptical radio wave reflection plate 14.
Since the focus is concentrated on the third area C, the interrogation signal can be prevented from being transmitted and scattered to the front side of the substantially elliptical radio wave reflection plate 14, that is, the side opposite to the reflection surface 15. Therefore,
It is possible to reduce radio wave interference with other wireless communication devices.

The interrogator antenna 12 is a small antenna having wide directional characteristics in which radio waves are radiated at wide directional angles.
However, the interrogation signal can be efficiently focused and the signal can be effectively used.

Since the interrogation signal reflected by the substantially elliptical radio wave reflection plate 14 is focused on the third area C including the second focal point 17 of the approximately elliptical radio wave reflection plate 14, the interrogation signal of the third area C is obtained. By arranging the wireless tag 13 in the third area C, it is possible to improve the communication accuracy between the wireless tag 13 arranged in the third area C and the interrogator 11, The communication distance between the antenna 12 and the wireless tag 13 can be extended.

RFID according to the first embodiment described above
In the system 10, the interrogator antenna 12 is arranged at the first focal point 16 of the reflection surface 15 of the substantially elliptical radio wave reflection plate 14, but as another embodiment of the present invention, the interrogator antenna 12 is arranged at the first focus point. It may be arranged at a position deviated from the focal point 16, that is, at a position moved to the front, rear, left and right, and up and down from the first focal point 16 with respect to the substantially elliptical radio wave reflection plate 14. By arranging the interrogator antenna 12 in this way, the interrogation signal transmitted from the interrogator antenna 12 is reflected by the reflecting surface 15 of the substantially elliptical radio wave reflection plate 14 and has a predetermined size in the vicinity of the second focal point 17. Since the light is focused on the area, the third area C, which is an area where the interrogation signal is strong, can be expanded.

As a further embodiment of the present invention, when the reflecting surface 15 of the substantially elliptical radio wave reflecting plate 14 is a curved surface similar to a spheroidal surface or an elliptic cylindrical surface, the signal transmitted from the interrogator antenna 12 is the first. Since it focuses on a region having a predetermined size in the vicinity of the second focal point 17, the third region which is a strong signal region
The range of the area C can be expanded.

RFID according to the first embodiment described above
In the system 10, only one interrogator 11 is provided, but as still another embodiment of the present invention, the interrogator antenna 12 is not limited to one, and as shown by a virtual line in FIG. The second interrogator antenna 12a and the third interrogator antenna 12b may be additionally provided near the interrogator antenna 12. The second interrogator antenna 12a and the third interrogator antenna 12b are the interrogator antenna 1
The second interrogator antenna 1 has the same configuration as that of
2a and the 3rd interrogator antenna 12b may be called the interrogator antenna 12, respectively. The plurality of interrogator antennas 12 are connected to the interrogator 11.

The interrogation signal transmitted from each interrogator antenna 12 is reflected by the reflecting surface 15 of the substantially elliptical radio wave reflection plate 14, travels in different directions, and is focused in different areas. The antenna 12 is arranged. That is, the interrogation signal transmitted from the second interrogator antenna 12 a is reflected by the reflecting surface 15 of the substantially elliptical radio wave reflection plate 14 and near the second focus 17 of the reflecting surface 15 of the substantially elliptical radio wave reflection plate 14. In the region, the focus is concentrated on the fourth region D, which is different from the third region C. The interrogation signal transmitted from the third interrogator antenna 12b is a substantially elliptical radio wave reflection plate 1
A fifth area E which is reflected by the fourth reflection surface 15 and is near the second focus 17 of the reflection surface 15 of the substantially elliptical radio wave reflection plate 14 and which is different from the third area C and the fourth area D. Focus on. As a result, the region where the interrogation signal is strong can be expanded in the vicinity of the second focal point 17, and the second focal point 17
The communication accuracy between the wireless tag 13 and the interrogator 11 arranged in the vicinity is improved.

The interrogation signal transmitted from the plurality of interrogator antennas 12 may be time-divided and may be transmitted simultaneously.

If the interrogator antennas 12 have different communication accuracies due to obstacles, the interrogator 11 selects the information from the interrogator antenna 12 having the highest communication accuracy, so that the RFID system 10 as a whole is selected. As a result, the communication accuracy is improved.

The plurality of interrogator antennas 12 described above are
Although it is connected to one interrogator 11, a plurality of interrogators 11 may be provided and a plurality of interrogator antennas 12 may be connected to different interrogators 11, respectively, as still another embodiment of the present invention. Also in this case, the plurality of interrogator antennas 12
The interrogation signal transmitted from S may be time-divided and may be transmitted simultaneously.

FIG. 6 is a diagram showing the configuration of the RFID system 30 according to the second embodiment of the present invention. The RFID system 30, which is a wireless communication device, has the same configuration as the RFID system 10 of the first embodiment described above,
Since the RFID system 10 is different from the RFID system 10 only in the arrangement of the interrogator antenna 12 and the wireless tag 13, the same components as those in the RFID system 10 according to the present embodiment are designated by the same reference numerals and description thereof will be omitted.

The RFID system 30 includes the interrogator 11 and
An interrogator antenna 12 connected to the interrogator 11, a wireless tag 13, and a substantially elliptical radio wave reflection plate 14 are provided. In FIG. 6, a cross section of the substantially elliptical radio wave reflection plate 14 is shown.

In the RFID system 30, the interrogator antenna 12 is arranged at the second focal point 17 of the reflecting surface 15 of the substantially elliptical radio wave reflection plate 14 so as to be oriented toward the substantially elliptical radio wave reflection plate 14.
The first focus 1 on the area between the interrogator antenna 12 and the substantially elliptical radio wave reflection plate 14 and on the reflection surface of the approximately elliptical radio wave reflection plate 14
A plurality of wireless tags 13 are arranged in the vicinity of 6.

When the interrogator antenna 12 transmits the interrogation signal, the RFID tag 13 disposed between the interrogator antenna 12 and the substantially elliptical radio wave reflection plate 14 is supplied with sufficient acquisition communication power to interrogate the interrogator. 11 can be communicated with high accuracy. On the other hand, in the signal transmitted from the interrogator antenna 12,
The inquiry signal not received by the wireless tag 13 arranged between the interrogator antenna 12 and the substantially elliptical radio wave reflection plate 14 is
Toward the substantially elliptical radio wave reflection plate 14, the approximately elliptical radio wave reflection plate 14
It is reflected by the reflecting surface 15 of the first focal point 16 and is focused on the first focal point 16 and the sixth region F in the immediate vicinity of the first focal point 16.
Therefore, the inquiry signal in the sixth area F becomes strong. Therefore, it is possible to improve the communication accuracy between the wireless tag 13 and the interrogator 11 arranged in the sixth area F, which is an area where the inquiry signal is strong. It is desirable that the interrogator 11 is arranged at a position where it does not interfere with the interrogation signal and the response signal passing between the interrogator antenna 12 and the wireless tag 13.

The response signal reflected and transmitted from the wireless tag 13 is received by the interrogator antenna 12 directly or via the reflecting surface 15 of the substantially elliptical radio wave reflecting plate 14.

If the interrogation signal transmitted from the interrogator antenna 12 is linearly polarized, basically the interrogation signal focused near the first focus 16 is also linearly polarized. For example, the interrogator antenna 12 If the interrogation signal transmitted from the right-hand circularly polarized wave is a right-handed circularly polarized wave, the interrogating signal focused near the first focus 16 is a left-handed circularly polarized wave. By arranging the second wireless tag 13b shown in FIG. 5, which is capable of communicating with, communication efficiency is improved.

As described above, in the RFID system 30,
The interrogation signal transmitted from the interrogator antenna 12 arranged at the second focus of the reflecting surface 15 of the substantially elliptical radio wave reflection plate 14,
The signal not received between the interrogator antenna 12 and the substantially elliptical radio wave reflection plate 14 is reflected by the reflection surface 15 of the approximately elliptical radio wave reflection plate 14.
Since the inquiry signal is reflected by, it is possible to prevent the interrogation signal from being scattered to the back surface of the substantially elliptical radio wave reflection plate 14, that is, the reflection surface 15 and the reflection side. Therefore, it is possible to reduce the interference of radio waves with other wireless communication devices.

The interrogator antenna 12 is a small antenna having wide directional characteristics in which radio waves are radiated at wide directional angles.
However, the interrogation signal can be efficiently focused and the signal can be effectively used.

The interrogation signal reflected by the substantially elliptical radio wave reflection plate 14 is intensively focused on the sixth region F including the first focus 16 of the approximately elliptical radio wave reflection plate 14, so that the sixth region F is obtained.
The question signal of becomes stronger, and the wireless tag 1
By disposing 3, the interrogation signal can be effectively used, the communication accuracy between the wireless tag 13 disposed in the sixth area F and the interrogator 11 can be improved, and the interrogator antenna The communication distance between the wireless tag 12 and the wireless tag 13 can be extended.

In the present embodiment, the wireless tag 13 is arranged between the interrogator antenna 12 and the substantially elliptical radio wave reflection plate 14 and in the vicinity of the first focus 16, but still another embodiment of the present invention. As a form, the wireless tag 13 may be disposed between the interrogator antenna 12 and the substantially elliptical radio wave reflection plate 14 or in any one of the first focal point vicinity 16.

RFID according to the second embodiment described above
In the system 30, the interrogator antenna 12 is arranged at the second focal point 17 of the reflection surface 15 of the substantially elliptical radio wave reflection plate 14, but as another embodiment of the present invention, the interrogator antenna 12 is arranged at the second focal point. It may be arranged at a position deviated from the focal point 17, that is, at a position moved from the second focal point 17 with respect to the substantially elliptical radio wave reflection plate 14 to the front, rear, left and right, and up and down. By arranging the interrogator antenna 12 in this manner, the interrogation signal transmitted from the interrogator antenna 12 is reflected by the reflecting surface 15 of the substantially elliptical radio wave reflection plate 14 and has a predetermined size in the vicinity of the first focus 16. Since the light is focused on the area, the area where the signal is strong can be expanded.

RFID according to the second embodiment described above
In the system 30, only one interrogator 11 is provided, but as still another embodiment of the present invention, the number of interrogator antennas 12 is not limited to one, and the interrogator antenna 12 is located near the interrogator antenna 12, that is, the second interrogator antenna 12. A plurality of interrogator antennas 12 may be provided near the focal point 17. The plurality of interrogator antennas 12 are connected to the interrogator 11.

The interrogation signal transmitted from each interrogator antenna 12 is reflected by the reflecting surface 15 of the substantially elliptical radio wave reflection plate 14, travels in different directions, and is focused in different areas. The antenna 12 is arranged. As a result, the region where the interrogation signal is strong can be widened in the vicinity of the first focus 16, and the communication accuracy between the wireless tag 13 and the interrogator 11 arranged in the vicinity of the first focus 16 can be improved.

The interrogation signals transmitted from the plurality of interrogator antennas 12 may be time-divided and may be transmitted simultaneously.

When the interrogator antennas 12 have different communication accuracies due to obstacles, the interrogator 11 selects the information from the interrogator antenna 12 having the highest communication accuracy, so that the RFID system 30 as a whole. As a result, the communication accuracy is improved.

The plurality of interrogator antennas 12 described above are
Although it is connected to one interrogator 11, a plurality of interrogators 11 may be provided and a plurality of interrogator antennas 12 may be connected to different interrogators 11, respectively, as still another embodiment of the present invention. Also in this case, the plurality of interrogator antennas 12
The interrogation signal transmitted from S may be time-divided and may be transmitted simultaneously.

In still another embodiment of the present invention, the RFID system is configured by combining the RFID system 10 according to the first embodiment and the RFID system 30 according to the second embodiment described above. Good. That is, the interrogator antennas 12 are arranged near the first focus 16 and near the second focus 17, respectively. One interrogator antenna 12
From the wireless tag 13 and the response signal reflected and transmitted from the wireless tag 13 is received by the two interrogator antennas 12. This improves the communication accuracy between the interrogator 11 and the wireless tag 13.

FIG. 7 is a diagram showing the configuration of an RFID system 40 according to the third embodiment of the present invention. RFID
Since the system 40 has a configuration including another radio wave reflection plate 41 in addition to the configuration of the RFID system 30 according to the second embodiment, the same components as those of the RFID system 30 are designated by the same reference numerals. And the description is omitted. In FIG. 7, a substantially elliptical radio wave reflection plate 14 and another radio wave reflection plate 41
Is shown in cross section.

RFID system 40 which is a wireless communication device
Is configured to include an interrogator 11, an interrogator antenna 12 connected to the interrogator 11, a wireless tag 13 that is a responder, a substantially elliptical radio wave reflection plate 14, and another radio wave reflection plate 41. .

The other radio wave reflection plate 41 is a reflection plate having a reflection surface for reflecting a radio wave signal. In this embodiment, it has the same shape as the substantially elliptical radio wave reflection plate 14, and the substantially elliptical radio wave reflection plate 14 has the same shape. It has a reflecting surface 42 including a part of the reflecting surface 15.
In the RFID system 40, the reflection surface 42 of the other radio wave reflection plate 41 faces the reflection surface 15 of the substantially elliptical radio wave reflection plate 14, and the two focal points of the reflection surface 42 of the other radio wave reflection plate 41 are
It is arranged so as to coincide with the two focal points of the reflecting surface 15 of the substantially elliptical radio wave reflecting plate 14.

The inquiry signal transmitted from the interrogator antenna 12 and reflected by the reflecting surface 15 of the substantially elliptical radio wave reflection plate 14 is
After being focused on the sixth area F near the first focus 16, it is reflected by the reflection surface 42 of the other radio wave reflection plate 41, and the second focus 17 and an area very close to the second focus 17. Can be focused on. Therefore, since the interrogation signal can be reflected and used in the area sandwiched between the two radio wave reflection plates, the interrogation signal can be used more effectively. In addition, the substantially elliptical radio wave reflection plate 14 and other radio wave reflection plates 4
It is possible to efficiently prevent the interrogation signal from being radiated to the outside from the area sandwiched between 1 and 1, and it is possible to further reduce the interference of radio waves to other wireless communication systems.

Although the other radio wave reflection plate 41 described above has a shape substantially similar to that of the elliptical radio wave reflection plate 14, another radio wave reflection plate 41 of another embodiment of the present invention is an elliptic curve. Alternatively, a non-ellipsoidal radio wave reflection plate 44 having a reflection surface 43 having a shape different from the shape including a part of a curve similar thereto may be used. The non-ellipsoidal radio wave reflection plate 44 is
A reflecting plate having a reflecting surface 43 for reflecting a radio wave signal, wherein the reflecting surface 43 is a flat surface 43 as shown by an imaginary line in FIG.
a, the cross section is configured to include a part of the paraboloid or the spherical surface 43b. Such a reflection surface 4 of the non-ellipsoidal radio wave reflection plate 44
By arranging 3 so as to face the reflecting surface 15 of the substantially elliptical radio wave reflection plate 14, it is possible to efficiently prevent the question signal from being radiated to the outside.

When the non-ellipsoidal radio wave reflection plate 44 is used as the other radio wave reflection plate 41, the substantially elliptical radio wave reflection plate 14 is used.
It is possible to focus the interrogation signal on an area different from the area where the reflective surface 15 of FIG. The communication accuracy between the interrogator 11 and the wireless tag 13 can be improved in a wide range within the area sandwiched between the two radio wave reflection plates.

FIG. 8 is a diagram showing the configuration of an RFID system 50 according to the fourth embodiment of the present invention. RFID
The system 50 is the RF according to the first embodiment described above.
The configuration is such that the substantially elliptical radio wave reflection plate 14 of the ID system 10 is replaced with a second substantially elliptical radio wave reflection plate 51, and the other configurations are the same as the RFID system 50. Are denoted by the same reference numerals and description thereof will be omitted. In FIG. 8, a second substantially elliptical radio wave reflection plate 51 is provided.
Is shown in cross section.

RFID system 50 which is a wireless communication device
Includes an interrogator 11, an interrogator antenna 12 connected to the interrogator 11, a wireless tag 13, and a second substantially elliptical radio wave reflection plate 51.

The second substantially elliptical radio wave reflection plate 51 is a reflection plate having a reflection surface 52 for reflecting a radio wave signal. The reflecting surface 15 of the substantially elliptical radio wave reflection plate 14 of the first embodiment described above.
Is a spheroidal surface, an elliptic cylindrical surface, or a part of a curved surface similar to these, the reflecting surface 52 of the second substantially elliptical radio wave reflection plate 51 of the present embodiment is a spheroidal surface, an elliptic cylindrical surface, or An inner surface of a curved surface similar to these, for example, an inner surface of a curved surface formed of an elliptic cylinder surface. The difference between the reflecting surface 15 of the substantially elliptical radio wave reflecting plate 14 and the reflecting surface 52 of the second substantially elliptical radio wave reflecting plate 52 is that the reflecting surface is a curved surface including only a part of the elliptic curve, or the entire elliptic curve. It is a difference whether or not it is a curved surface including almost all, and the reflecting surface 52 of the second elliptical radio wave reflecting plate 51 partially includes the reflecting surface 15 of the substantially elliptical radio wave reflecting plate 14.

The interrogator antenna 12 has a first focal point 16 which is one focal point of the reflecting surface 52 of the substantially elliptical radio wave reflecting plate 51.
, The second focus 17 which is the other focus is directed. The wireless tag 13 performs efficient communication in consideration of the degree of fabrication of the reflecting surface 52 of the substantially elliptical radio wave reflection plate 51 and the disturbance of the surrounding radio wave condition caused by the placement of the interrogator antenna 12 near the first focus 16. The RFID system 10 according to the first embodiment is arranged in a region where
In the vicinity of the interrogator antenna 12 and the second focus 1
By being arranged in the vicinity of 7, the communication with the interrogator 11 can be performed with high accuracy.

In the RFID system 50, the interrogator antenna 12 and the wireless tag 13 are arranged inside the reflecting surface 52 of the second substantially elliptical radio wave reflecting plate 51.
Radiation of radio waves from inside to outside can be further reduced, and interference of radio waves with other wireless communication systems can be further reduced.

The interrogator 11 is provided outside the reflecting surface 52 of the second substantially elliptical radio wave reflection plate 51 so as not to interfere with the interrogation signal and the response signal transmitted and received between the interrogator antenna 12 and the wireless tag 13. It is desirable to be arranged.

RFID according to the fourth embodiment described above
In the system 50, only one interrogator 11 is provided, but as yet another embodiment of the present invention, the interrogator antenna 12 is not limited to one, and the interrogator antenna 12 can be used as shown by a virtual line in FIG. The second interrogator antenna 12a and the third interrogator antenna 12b may be additionally provided near the interrogator antenna 12. Hereinafter, the second interrogator antenna 1
2a and the 3rd interrogator antenna 12b may be called the interrogator antenna 12, respectively. The plurality of interrogator antennas 12 are connected to the interrogator 11.

The interrogation signal transmitted from each interrogator antenna 12 is reflected by the reflecting surface 52 of the second substantially elliptical radio wave reflection plate 51.
By arranging each interrogator antenna 12 so that each interrogator antenna 12 is reflected by, travels in different directions, and is focused in different areas, a strong interrogation signal area can be widened in the vicinity of the second focus 17. The communication accuracy between the wireless tag 13 arranged near the second focal point 17 and the interrogator 11 is improved. The interrogation signal transmitted from the plurality of interrogator antennas 12 may be time-divided and may be transmitted simultaneously.

FIG. 9 is a diagram showing the configuration of an RFID system 60 according to the fifth embodiment of the present invention. RFID
The system 60 is the RF according to the fourth embodiment described above.
The RFID system 50 has the same configuration as the ID system 50, and is different from the RFID system 50 according to the above-described fourth embodiment in the arrangement of the interrogator antenna 12 and the wireless tag 13, and thus the same configuration as the RFID system 50. Are denoted by the same reference numerals and description thereof will be omitted. In FIG. 9, the cross section of the second substantially elliptical radio wave reflection plate 51 is shown.

RFID system 60 which is a wireless communication device
Is an interrogator 11 and first to third devices connected to the interrogator 11.
Interrogator antennas 12a, 12b, 12c and wireless tag 1
3 and a second substantially elliptical radio wave reflection plate 51. First to third interrogator antennas 12a, 12b, 12c
Has the same configuration as the interrogator antenna 12 described above.

The first to third interrogator antennas 12a, 12
At least one of the antennas b and 12c is arranged in the vicinity of an imaginary straight line that includes one of the focal points of the reflecting surface 52 of the second substantially elliptical radio wave reflection plate 51 and passes through the reflecting surface 52. It is arranged so as to point to the reflecting surface 52 of the second substantially elliptical radio wave reflection plate 51 substantially parallel to.
In the present invention, the vicinity of the virtual straight line includes the virtual straight line. In the present invention, substantially parallel includes parallel.

In the present embodiment, the first interrogator antenna 12a is located outside the reflecting surface 52 of the second substantially elliptical radio wave reflection plate 51 and has an opening provided in the second substantially elliptical radio wave reflection plate 51. The second substantially elliptical radio wave reflection is arranged in the vicinity of a virtual straight line including the first focal point 16 of the reflecting surface 52 of the second substantially elliptical radio wave reflecting plate 51 and passing through the reflecting surface 52, and parallel to the virtual straight line. The reflection surface 52 of the plate 51 is directed. The second interrogator antenna 12b includes the reflecting surface 5 of the second substantially elliptical radio wave reflection plate 51.
The second focal point 17 of the reflecting surface 52 of the second substantially elliptical radio wave reflection plate 51, including the second focus 17 and outside the second elliptical radio wave reflection plate 51 in the vicinity of the opening provided in the second substantially elliptical radio wave reflection plate 51. The reflecting surface 52 of the second substantially elliptical radio wave reflection plate 51 is arranged parallel to the virtual straight line passing through the virtual straight line.

The interrogation signal transmitted from the first interrogation signal 12a passes through the first focal point 16, is reflected by the reflecting surface 52 of the second substantially elliptical radio wave reflection plate 51, and is transmitted to the second focal point 17 and the second focal point 17. The focus is concentrated on an area in the immediate vicinity of the second focal point 17.
The interrogation signal transmitted from the second interrogator antenna 12b passes through the second focal point 17, and the second substantially elliptical radio wave reflection plate 5
The first focal point 16 and the first focal point 16 are reflected by the first reflecting surface 52.
Focuses very close to the focal point 16 of the. This makes it possible to form a region where the interrogation signal is strong near the first and second focal points 16 and 17. In this way, the two focal points of the reflecting surface 52 of the second substantially elliptical radio wave reflection plate 51 form an area where the interrogation signal becomes strong. Therefore, the wireless tag 13 arranged in this area can efficiently interrogate the interrogator. The signal from the antenna can be received, and the communication accuracy is improved.

The third interrogator antenna 12c is located outside the reflecting surface 52 of the second substantially elliptical radio wave reflection plate 51, and is the second
Of the first interrogator antenna 12a and the second interrogator antenna 12 arranged near the opening of the substantially elliptical radio wave reflection plate of
The interrogation signal is transmitted so as to complement a region different from the region where the interrogation signal transmitted from b is focused, that is, the region where the interrogation signal transmitted from the first and second interrogator antennas 12a and 12b is weak. As a result, the communication accuracy between the wireless tag 13 and the interrogator 11 arranged inside the reflecting surface 52 of the second substantially elliptical radio wave reflection plate 51 can be comprehensively improved.

FIG. 10 is a perspective view showing an RFID system 70 according to the sixth embodiment of the present invention. RFID
The system 70 is the RF according to the sixth embodiment described above.
Since the carrier device is provided in addition to the configuration of the ID system 60, the same components as those of the RFID system 70 are designated by the same reference numerals and description thereof will be omitted. In the present embodiment, the reflecting surface 52 of the substantially elliptical radio wave reflection plate 51 is an elliptic cylinder surface or a curved surface similar thereto, for example, an elliptic cylinder surface.

RFID system 70 which is a wireless communication device
Then, a part of the belt conveyer 71, which is a conveying device, is provided inside the elliptic cylindrical surface, which is the reflecting surface 52 of the substantially elliptical radio wave reflection plate 51, along the extending direction of the elliptic cylindrical surface. RFI
In the D system 70, the RFID tag 13 is attached to the object 72 placed and conveyed on the belt conveyor 71, and the direction from one end to the other end of the opening of the elliptic cylinder surface, that is, the arrow in FIG. The object 72 is moved toward the belt conveyor 7 in the direction indicated by G.
While moving at 1, the wireless tag 13 and the interrogator 11 communicate with each other.

The first, second and third interrogator antennas 12
The a, 12b, and 12c are arranged at a predetermined interval in the extending direction of the belt conveyor 71, that is, the conveying direction of the object 72. By this, each interrogator antenna 12a, 1
A wide area is formed in which the interrogation signal transmitted from 2b and 12c is strong. The wireless tag 13 is attached to the object 72,
The interrogator 11 is attached to the objects 72 that are successively conveyed by the belt conveyor 71 by being configured to pass through a region where the interrogation signal is strong inside the reflecting surface 52 of the substantially elliptical radio wave reflection plate 51. Communication with the wireless tag 13 can be performed with high accuracy.

FIG. 11 is a diagram showing the configuration of an RFID system 80 according to the seventh embodiment of the present invention. The RFID system 80, which is a wireless communication device, includes an interrogator 11 and
The interrogator antenna 12 connected to the interrogator 11, the wireless tag 13, and the third substantially elliptical radio wave reflection plate 81 are included. The interrogator 11, the interrogator antenna 12, and the wireless tag 13 are the RFID system 10 according to the first embodiment.
Interrogator 11, interrogator antenna 12, and wireless tag 13
Since the configuration is the same as, the same reference numerals are given and the description thereof is omitted. In FIG. 11, the third substantially elliptical radio wave reflection plate 81
Is shown in cross section.

The third substantially elliptical radio wave reflection plate 81 is a reflection plate having a reflection surface 82 for reflecting a radio wave signal. The reflecting surface 82 of the third substantially elliptical radio wave reflection plate 81 is a curved surface that is a concave surface that curves inward, and that includes a curve excluding a portion that intersects a straight line that passes through two focal points of an elliptic curve or a similar curve. In the present embodiment, the elliptic curve is formed of a curved surface including a curve excluding a portion intersecting a straight line passing through two focal points. That is, it is a so-called offset-positioned reflector. Such curved surface includes a part of a spheroidal surface and an elliptic cylindrical surface, but in the present embodiment, for example, the reflective surface 7 is used.
Let 2 be a part of the elliptic cylinder surface.

The interrogator antenna 12 is arranged in the vicinity of a virtual straight line including the first focal point 16 which is one of the focal points of the reflecting surface 82 of the third substantially elliptical radio wave reflecting plate 81 and passing through the reflecting surface 82. The reflecting surface 82 of the substantially elliptical radio wave reflection plate 81 is directed substantially parallel to the virtual straight line.

The wireless tag 13 is arranged near the second focal point 17, which is the other focal point of the reflecting surface 82 of the third substantially elliptical radio wave reflecting plate 81. In addition, the wireless tag 13 has a second focus 17
It may be moved so as to pass through the vicinity.

The interrogation signal transmitted from the interrogator antenna 12 is reflected by the reflecting surface 82 of the third substantially elliptical radio wave reflection plate 81 and concentrated and focused on the second focal point 17. With such a configuration, the interrogator antenna 12 and the wireless tag 13 are arranged on the propagation path between the interrogator antenna 12 and the wireless tag 13 via the third substantially elliptical radio wave reflection plate 81. There is no, and it does not get in the way. Therefore, the intensity of the interrogation signal at the second focus 17 can be increased.

When the third substantially elliptical radio wave reflection plate 81 is a curved surface including a curve that does not intersect a straight line passing through two focal points of a curve similar to an elliptic curve, the two focal points mean an elliptic curve. When a curve similar to the above is approximated to an elliptic curve, the two focal points of the approximated elliptic curve are set.

FIG. 12 is a diagram showing an RFID system 90 according to the eighth embodiment of the present invention. An RFID system 90, which is a wireless communication device, includes an interrogator 91, a transmitting interrogator antenna 92, a receiving interrogator antenna 93,
The wireless tag 13 and the fourth to sixth substantially elliptical radio wave reflection plates 94
a, 94b, 94c. In FIG. 12, the fourth to sixth substantially elliptical radio wave reflection plates 94a, 94b,
The cross section of 94c is shown.

The interrogator 91 is the transmitting interrogator antenna 92.
91a connected to the receiver and the interrogator antenna 9 for reception
3 and a receiver 91b connected to the receiver 3. The transmitter 91a has the same configuration as the transmitting unit of the interrogator 11 of the above-described first embodiment, and the receiver 91b has the same configuration as the receiving unit of the interrogator 11 of the above-described first embodiment. Since this is a configuration, description thereof will be omitted. Of course, the transmitter 91a and the transmitting interrogator antenna 92 may have the same transmitting / receiving function as the interrogator 11 and the interrogator antenna 12 described above.

The transmitting interrogator antenna 92 and the receiving interrogator antenna 93 have the same structure as the interrogator antenna 12 of the first embodiment described above. The transmitting interrogator antenna 92 transmits an inquiry signal to the wireless tag 13, and the receiving interrogator antenna 93 receives a response signal reflected and transmitted from the wireless tag 13.

The fourth to sixth substantially elliptical radio wave reflecting plates 94a, 94.
Each of the reflecting surfaces 95a, 95b, 95c of 4b, 94c has the same shape as the reflecting surface 72 of the third substantially elliptical radio wave reflecting plate 71 of the seventh embodiment described above. The one focus of the reflecting surface 95a of the fourth substantially elliptical radio wave reflecting plate 94a and the one focus of the reflecting surface 95b of the fifth substantially elliptical radio wave reflecting plate 94b are made to coincide with each other, and the reflection of the fifth substantially elliptical radio wave reflecting plate 94b is performed. The other focus of the surface 95b and the reflecting surface 95 of the sixth substantially elliptical radio wave reflecting plate 94c.
The fourth to sixth substantially elliptical radio wave reflection plates 94a, 94b, and 94c are arranged such that one focus of c is matched.

The transmitting interrogator antenna 92 includes one focal point 96 of the fourth substantially elliptical radio wave reflecting plate 94a, and includes the reflecting surface 9
It is arranged in the vicinity of a virtual straight line passing through 5a and is directed substantially parallel to the virtual straight line to the reflecting surface 95b of the substantially elliptical radio wave reflecting plate 94a.

The interrogation signal transmitted from the transmitting interrogator antenna 92 passes through one focal point 96 of the fourth substantially elliptical radio wave reflection plate 94a and is reflected by the reflecting surface 95a of the fourth substantially elliptical radio wave reflection plate 94a. Then, the other focus of the fourth substantially elliptical radio wave reflection plate 94a and the one focus of the fifth substantially elliptical radio wave reflection plate 94b are focused on each other in a focal point 97 and a region in the immediate vicinity of the focal point 97. . After passing through the focal point 97, the interrogation signal is reflected by the reflecting surface 95b of the fifth substantially elliptical radio wave reflection plate 94b, and the other focal point of the fifth substantially elliptical radio wave reflection plate 94b and the sixth substantially elliptical radio wave. The focal point 98 where one of the focal points of the reflector 94c coincides with each other, and the focal point 98 and a region in the immediate vicinity of the focal point 98 are focused again. Further, the interrogation signal, after passing through the focal point 98, is reflected by the reflecting surface 95c of the sixth elliptical radio wave reflecting plate 94c.
And is focused again in the other focus 99 of the sixth substantially elliptical radio wave reflection plate 94c and a region in the immediate vicinity of the focus 99.

Therefore, in the focal points 97, 98 and 99 and in the vicinity of the focal points 97, 98 and 99, areas where the interrogation signal is strong are formed. By placing the wireless tag 13 in this area and performing communication, the interrogator 11 and the wireless tag 13
The communication accuracy with can be improved.

The interrogator antenna for reception 93 is arranged at a position away from the interrogator antenna for transmission 92 and at a position where it is easy to receive a response signal from each of the above-mentioned wireless tags 13.

In the example of FIG. 12, three substantially elliptical radio wave reflection plates 94a, 94b, 94c are used, but four or more substantially elliptical radio wave reflection plates are used, and one focal point is the other substantially elliptical radio wave reflection plate. May be provided in combination so that the other focus is aligned with another substantially elliptical radio wave reflection plate.
Further, a configuration may be employed in which a plurality of substantially elliptical radio wave reflection plates including two substantially elliptical radio wave reflection plates that are arranged so as to match two focal points are provided in combination.

As described above, in the RFID system 90, the area where the interrogation signal is strong can be widened.
The communication accuracy between the interrogator 91 and the wireless tag 13 is improved. Further, by using a plurality of substantially elliptical radio wave reflection plates, the propagation direction of the inquiry signal can be changed, and the degree of freedom in the arrangement of the RFID system 90 is increased.

Since the transmitter 91a is connected to the transmitting interrogator antenna 92 and the receiver 91b is connected to the receiving interrogator antenna 93, the transmitting interrogator antenna 92 is connected.
And the receiving interrogator antenna 93 are arranged apart from each other, the transmitting interrogator antenna 92 and the receiving interrogator antenna 93 are connected to an interrogator having one transmitting unit and one receiving unit. More freedom than placement,
Even if the transmitting interrogator antenna 92 and the receiving interrogator antenna 93 are arranged apart from each other, the transmitting interrogator antenna 9
It is possible to shorten the paths such as the connection line between the transmitter 2 and the transmitter 91a and the path between the reception interrogator antenna 93 and the receiver 91b, and the influence of these paths on the signal. Can be prevented.

In the RFID system 80 of the eighth embodiment described above, the transmitting interrogator antenna 92 has the transmitter 9
1a is connected, and the receiver 91b is connected to the receiving interrogator antenna 93. However, as still another embodiment of the present invention, a transmitting interrogator antenna 92 and a receiving interrogator antenna 93 are provided. May be connected to the interrogator 11 shown in the first embodiment. One interrogator 11
When performing communication using the interrogator antenna 12 and the interrogator antenna 12, considering that the interrogator antenna 12 reflects the interrogator signal when the interrogator 11 sends the interrogator signal to the interrogator antenna 12, It is necessary to separate the response signal received by the interrogator antenna 12, but by providing the transmitting interrogator antenna 92 and the receiving interrogator antenna 93, the response signal received from the wireless tag 13 can be processed. It will be easy.

FIG. 13 is a diagram showing the configuration of the RFID system 100 according to the ninth embodiment of the present invention. RF
The ID system 100 is the R of the first embodiment described above.
The configuration is the same as that of the FID system 10, and only the arrangement of the interrogator antenna 12 and the wireless tag 13 is different from that of the RFID system 10. Therefore, the portions having the same configurations as those of the RFID system 10 will be denoted by the same reference numerals. Is omitted. In FIG. 13, the cross section of the substantially elliptical radio wave reflection plate 14 is shown.

The RFID system 10 which is a wireless communication device
0 is an interrogator 11, an interrogator antenna 12 connected to the interrogator 11, a wireless tag 13, and a substantially elliptical radio wave reflection plate 14
With. The interrogator 11 and the wireless tag 13 can communicate with each other directly and via the reflecting surface 15 of the substantially elliptical radio wave reflecting plate 14.

The interrogator antenna 12 is arranged so as to face the reflecting surface 15 of the substantially elliptical radio wave reflecting plate 14. The inquiry signal transmitted from the interrogator antenna 12 is a substantially elliptical radio wave reflection plate 1
It is reflected by the reflecting surface 15 of No. 4 and received by the wireless tag 13. The response signal from the wireless tag 13 is received by the interrogator antenna 12 through a similar path.

By providing the substantially elliptical radio wave reflection plate 14 and reflecting the signal, it is possible to prevent the signal from being transmitted and scattered to the rear surface of the substantially elliptical radio wave reflection plate 14, that is, the surface opposite to the reflection surface 15. . As a result, it is possible to reduce the interference of radio waves with other wireless communication systems. Further, the signal can be collected in a region facing the reflecting surface 15 of the substantially elliptical radio wave reflection plate 14, and the signal can be effectively used.

The reflecting surface 15 of the substantially elliptical radio wave reflecting plate 14
Has a curved surface, the signal reflected by the reflecting surface 15 can be locally focused in a region of the substantially elliptical radio wave reflecting plate 14 facing the reflecting surface 15. Therefore,
By converging the signal transmitted from the interrogator antenna 12, a strong interrogation signal region can be easily formed. By arranging the wireless tag 13 in this interrogation signal strong region, the gain is improved, The communication accuracy between the device 11 and the wireless tag 13 can be improved, and the communicable distance between the interrogator antenna 12 and the wireless tag 13 can be extended.

By reflecting the interrogation signal using the substantially elliptical radio wave reflection plate 14, the signal propagation direction can be changed, and the degree of freedom in the arrangement of the interrogator antenna 12 and the wireless tag 13 can be increased.

In still another embodiment of the present invention, the RFID systems 10, 30, of the first, second, third, fourth, fifth, seventh, eighth and ninth embodiments described above are used. Four
0, 50, 60, 80, 90, 100 may be configured to communicate with the RFID tag 13 attached to the object 72 carried by the carrier device shown in the RFID system 70 of the sixth embodiment. . In this case, the interrogator 11 can communicate with the wireless tags 13 with high communication accuracy one after another by providing the carrier device so that the wireless tags 13 can pass through the area where the inquiry signal is focused.

In each of the embodiments described above, the wireless tag 13
Although a battery-less tag is used as the wireless tag 13, a tag having a battery may be used as the wireless tag 13 as still another embodiment of the present invention.

The RFID system is not limited to the configuration of each of the above-described embodiments, and these embodiments may be combined arbitrarily.

Further, the RFID systems 10, 30, 40, 50, 60, 70, 80, 9 according to the above-mentioned respective embodiments.
0,100 is factory automation (FA),
It can be suitably used in many fields such as office automation (OA), distribution, and physical distribution fields.

Although the RFID system has been described as the wireless communication system in each of the above-described embodiments, the present invention is applicable to, for example, Bluetooth and wireless LAN.
It can be applied to near field communication such as a wireless communication system such as Area Network).

[0148]

As described above, according to the present invention, a signal transmitted from an interrogator antenna is reflected by a substantially radio wave reflector having a reflecting surface including a part of an elliptic curve or a curve similar to the elliptic curve, and a response is obtained. Can be received by the vessel. By providing a substantially elliptical radio wave reflection plate and reflecting the signal,
It is possible to prevent the signal from transmitting to the back side of the substantially elliptical radio wave reflection plate, that is, the side opposite to the reflection surface and scattering. As a result, it is possible to reduce the interference of radio waves with other wireless communication systems. Further, the signal can be collected in an area facing the reflecting surface on the reflecting surface side of the substantially elliptical radio wave reflecting plate, and the signal can be effectively used. For example,
The transponder can directly receive the signal transmitted from the interrogator antenna, reflect the signal by the substantially elliptical radio wave reflection plate, and use both of them.

Further, since the reflecting surface of the substantially elliptical radio wave reflecting plate is a curved surface, the signal reflected by the reflecting surface can be locally focused within the area facing the reflecting surface of the substantially elliptical radio wave reflecting plate. it can. Therefore, by concentrating the signal transmitted from the interrogator antenna, a strong region of the signal can be easily formed, and by placing the transponder in the strong region of the signal, the gain is improved and the interrogator is increased. The communication accuracy between the interrogator antenna and the transponder can be improved, and the communicable distance between the interrogator antenna and the transponder can be extended.

Further, since the signal transmitted from the interrogator antenna can be reflected on the reflecting surface of the substantially elliptical radio wave reflection plate and guided to the responder, the propagation direction of the signal can be changed, and the interrogator antenna and the response can be changed. The degree of freedom of arrangement with the vessel is increased.

Further, according to the present invention, the signal transmitted from the interrogator antenna which is arranged near one of the focal points of the reflecting surfaces of the substantially elliptical radio wave reflecting plate and directs the reflecting surface has a substantially elliptic wave reflecting plate. After being reflected by the reflecting surface, it is focused near the other focus of the reflecting surface of the substantially elliptical radio wave reflecting plate. Therefore, an area where the signal transmitted from the interrogating antenna is strong can be easily formed near the other focus.

For example, even if the interrogator antenna has a wide directional characteristic, it is possible to easily form an area where the signal transmitted from the interrogator antenna is strong in the vicinity of the other focus of the reflecting surface of the substantially elliptical radio wave reflection plate. The communication accuracy between the interrogator and the responder can be improved.

According to the present invention, the elliptical radio wave reflection plate is disposed near the virtual straight line passing through the reflecting surface, including the focal point of one of the reflecting surfaces of the substantially elliptical radio wave reflecting plate, and is substantially parallel to the virtual straight line. By directing the reflecting surface of the plate, the signal transmitted from the interrogator antenna can be reflected by the reflecting surface of the elliptical radio wave reflecting plate and focused near the other focus of the reflecting surface of the substantially elliptical radio wave reflecting plate. it can. Therefore, a strong region of the signal transmitted from the interrogator antenna can be easily formed near the other focus.

For example, even if the interrogator antenna has a wide directional characteristic, it is possible to easily create a region where the signal transmitted from the interrogator antenna is strong in the vicinity of the other focus of the reflecting surface of the substantially elliptical radio wave reflection plate. The communication accuracy with the transponder can be improved. Further, even if the interrogator antenna is not provided near one of the focal points of the reflecting surface of the substantially elliptical radio wave reflection plate, a strong signal region can be formed near the other focal point of the reflecting surface of the substantially elliptical radio wave reflection plate. The interrogator antenna can be arranged at a position where it does not prevent the propagation of signals to and from the transponder and does not hinder communication.

Further, according to the present invention, the reflecting surface of the substantially elliptical radio wave reflection plate is a curved surface including a part of a curve excluding a portion intersecting a straight line passing through two focal points of an elliptic curve or a curve similar thereto. Prevents the interrogator antenna and the transponder from interfering with the signal propagation when the signal transmitted from either the interrogator antenna or the transponder is reflected by the substantially elliptical reflector and propagates to the other . For example, the interrogator antenna is arranged near one of the focal points on the reflecting surface of the substantially elliptical radio wave reflection plate, and the signal transmitted from the interrogator antenna is focused near the one focal point through the approximately elliptical radio wave reflection plate. Thus, the signal transmitted from the interrogator antenna is not disturbed by the interrogator antenna and the transponder itself when being guided to the transponder located there.

Further, according to the present invention, the plurality of substantially elliptical radio wave reflection plates are arranged such that at least one focal point of the reflection surfaces coincides with the focal points of the reflection surfaces of the other substantially elliptical radio wave reflection plates. In this case, in the two substantially elliptical radio wave reflection plates having the same focal point, the signal reflected by the one substantially elliptical radio wave reflection plate through one focal point of the one substantially elliptical radio wave reflection plate is reflected and then It passes through the other focal point of the substantially elliptical radio wave reflection plate and one focal point of the other substantially elliptical radio wave reflection plate, and focuses on the other focal point of the other substantially elliptical radio wave reflection plate.
Therefore, a strong signal region is formed near the focal point of each substantially elliptical radio wave reflection plate. Therefore, it is possible to widen the area where the signal is strong, and it is possible to increase the communicable distance between the interrogator antenna and the transponder by providing the substantially elliptical radio wave reflection plates as described above.

Further, according to the present invention, since the interrogator antenna for transmitting a signal to the transponder and the interrogator antenna for receiving the signal from the transponder are individually provided, transmission / reception with the transponder by one interrogator antenna is performed. It is not necessary to process the received signal from the transponder in consideration of that the signal sent from the interrogator to the interrogator antenna is reflected by the interrogator antenna connected to the interrogator itself, as in the case of , It becomes easy to process the received signal from the transponder.

Further, according to the present invention, the transponder efficiently arranges the signal transmitted from the interrogator antenna by disposing the transponder in the strong signal region near the other focus on the reflecting surface of the substantially elliptical radio wave reflection plate. Since it can be received well, the communication accuracy between the interrogator and the responder is improved.

Further, according to the present invention, the reflecting surface of the substantially elliptical radio wave reflecting plate is formed by including a part of a spheroidal surface, an elliptic surface, or a curved surface similar thereto. A spheroidal surface is a curved surface formed by rotating an ellipse around a major axis or a minor axis, and an elliptic cylindrical surface is formed by a locus that slides the ellipse in a direction intersecting its major axis and minor axis. Is a curved surface. Therefore, the signal transmitted from the interrogator antenna and reflected by the reflecting surface of the reflecting plate of the substantially elliptical radio wave reflecting plate can be efficiently focused.

Further, according to the present invention, a plurality of interrogator antennas connected to the interrogator are arranged so that the signals transmitted from the interrogator antennas are reflected by the reflecting surface of the substantially elliptical radio wave reflection plate and are focused on different areas. It is possible to provide a wide signal strong area, and it is possible to expand the communication range with high communication accuracy between the interrogator and the responder.

Further, according to the present invention, by communicating between the interrogator and the moving transponder while moving the transponder, the transponder can widely pass through a strong signal region, and the interrogator can , Can communicate with different responders one after another.

Further, according to the present invention, since the transmitting interrogator antenna is connected to the transmitter for generating a question and the receiving interrogator antenna is connected to the receiver, the transmitting interrogator antenna and the receiving interrogator are connected. The antenna and the antenna can be separated from each other, and the degree of freedom of arrangement is increased. Further, in this case, a path such as a connection line between each antenna and the transmitter and the receiver can be shortened, and the influence of the path such as the connection line on a signal can be reduced.

Further, according to the present invention, when the transponder receives the signal transmitted from the interrogator antenna, the transponder relates to the information stored in the memory unit based on the signal from the interrogator received by the processing circuit. By changing the reflection characteristic of the antenna in the modulator using the signal and reflecting the signal received by the antenna, the information stored in the memory can be read by the interrogator. For example, information about the object to which the transponder is attached can be read using the interrogator.

Further, according to the present invention, when the transponder receives the signal transmitted from the interrogator antenna by the antenna, the transponder demodulates the signal from the interrogator received by the processing circuit in the demodulator and writes the signal in the memory. By inserting the information, it is possible to give information from the interrogator and store the information in the memory unit. For example, information about the object to which the transponder is attached can be transmitted and written from the interrogator.

Further, according to the present invention, the signal reflected by the reflecting surface of the substantially elliptical radio wave reflection plate is further reflected by the reflecting surface of the non-ellipsoidal radio wave reflection plate, so that the signal can be used more effectively. In particular, when the reflecting surface of the substantially elliptical radio wave reflecting plate and the reflecting surface of the non-elliptical radio wave reflecting plate are arranged so as to face each other, it is possible to prevent signals from being scattered from the region sandwiched by the reflecting surfaces of the plurality of reflecting plates.

Further, according to the present invention, in the communication between the interrogator and the responder, the signal transmitted from the interrogator antenna is formed by a reflecting surface including a part of an elliptic curve or a curve similar thereto. It is reflected by a substantially elliptical radio wave reflection plate. Therefore, the signal transmitted from the interrogator antenna and not directly received by the transponder can be reflected by the reflecting surface of the substantially elliptical radio wave reflection plate and guided to the transponder again. Among the signals reflected by the reflecting surface of the elliptical wave reflector, the signals not received by the transponder are the reflecting surfaces of the non-elliptical wave reflector with a shape different from the shape including a part of the elliptic curve or a curve similar to it. The signal can be effectively used because it can be reflected by and guided to the transponder again. For example, the transponder
The signal transmitted from the interrogator antenna is directly received, reflected by the elliptical radio wave reflection plate, received, and reflected by the reflection surface of the elliptical radio wave reflection plate, and further reflected by the reflection surface of the non-elliptical radio wave reflection plate. It is possible to receive and use each signal. Further, in particular, by disposing the reflecting surface of the substantially elliptical radio wave reflecting plate and the reflecting surface of the non-ellipsoidal radio wave reflecting plate so as to face each other, it is possible to prevent signals from being scattered from a region sandwiched by the reflecting surfaces of the plurality of reflecting plates.

Further, since the reflecting surface of the substantially elliptical radio wave reflecting plate is a curved surface, the signal reflected by the reflecting surface can be locally collected in the area facing the reflecting surface of the substantially elliptical radio wave reflecting plate. it can. Therefore, by collecting signals transmitted from either the interrogator antenna or the transponder, a strong region of the signal can be easily formed,
By arranging the other one in the strong signal area, the gain can be improved, the communication accuracy between the interrogator and the responder can be improved, and the distance at which communication between the interrogator antenna and the responder is possible. Can be extended.

Since the signal transmitted from the interrogator antenna can be reflected by the reflecting surfaces of the substantially elliptical radio wave reflection plate and the non-ellipsoidal radio wave reflection plate and guided to the responder, the pointing of the interrogator antenna is indirectly performed. The degree of freedom in arranging the interrogator antenna and the responder is increased.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of an RFID system 10 according to a first embodiment of the present invention.

FIG. 2 is a substantially elliptical radio wave reflection plate 14 viewed from a first focus 16.
FIG.

FIG. 3 is a substantially elliptical radio wave reflection plate 14 seen from a first focus 16.
FIG.

FIG. 4 is a plan view of a first wireless tag 13a that mainly transmits and receives linearly polarized signals.

FIG. 5 is a second wireless tag 1 that mainly transmits and receives circularly polarized signals.
It is a top view of 3b.

FIG. 6 is a diagram showing a configuration of an RFID system 30 according to a second embodiment of the present invention.

FIG. 7 is a diagram showing a configuration of an RFID system 40 according to a third embodiment of the present invention.

FIG. 8 is a diagram showing a configuration of an RFID system 50 according to a fourth embodiment of the present invention.

FIG. 9 is a diagram showing a configuration of an RFID system 60 according to a fifth embodiment of the present invention.

FIG. 10 is a perspective view showing a configuration of an RFID system 70 which is a sixth embodiment of the present invention.

FIG. 11 is a diagram showing a configuration of an RFID system 80 according to a seventh embodiment of the present invention.

FIG. 12 is a diagram showing a configuration of an RFID system 90 according to an eighth embodiment of the present invention.

FIG. 13 is a diagram showing a configuration of an RFID system 100 according to a ninth embodiment of the present invention.

FIG. 14 is a diagram showing the basic configuration of a conventional RFID system 1.

[Explanation of symbols]

10, 30, 40, 50, 60, 70, 80, 90, 1
00 RFID system 11, 91 Interrogator 12 Interrogator antenna 13 Radio tag 14 Substantially elliptical radio wave reflection plate 15, 52, 72, 95a, 95b, 95c Reflection surface 16 First focus point 17 Second focus point 41 Other radio wave reflection plate 51 Second Approximate Elliptical Radio Wave Reflecting Plate 71 Third Approximate Elliptical Radio Wave Reflecting Plate 91a Transmitter 91b Receiver 92 Transmitting Interrogator Antenna 93 Receiving Interrogator Antenna 94a Fourth Substantial Elliptical Radio Wave Reflecting Plate 94b Fifth Abbreviation Elliptical radio wave reflection plate 94c Sixth elliptical radio wave reflection plate 96, 97, 98, 99 Focus

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 5B035 BB09 CA23                 5B058 CA15 KA24                 5K012 AA04 AB05 AC07 AE08 AE13                       BA03 BA07 BA13

Claims (14)

[Claims] 1. An interrogator, an interrogator antenna connected to the interrogator for transmitting a signal, and a reflecting surface including a part of an elliptic curve or a curve similar to the elliptic curve for reflecting the signal transmitted by the interrogator antenna. A substantially elliptical radio wave reflection plate, and a transponder capable of receiving a signal from the interrogator antenna and capable of communicating with the interrogator via at least the substantially elliptical radio wave reflection plate. A characteristic wireless communication system. 2. The interrogator antenna is disposed in the vicinity of the focal point of one of the reflecting surfaces of the substantially elliptical radio wave reflection plate,
The wireless communication system according to claim 1, wherein the wireless communication system is directed to the reflecting surface of the substantially elliptical radio wave reflection plate. 3. The interrogator antenna is arranged in the vicinity of a virtual straight line that includes one of the focal points of the reflecting surfaces of the substantially elliptical radio wave reflecting plate and passes through the reflecting surface, and is substantially parallel to the virtual straight line. The wireless communication system according to claim 1, wherein the wireless communication system is directed to the reflection surface of the reflection plate. 4. The reflecting surface of the substantially elliptical radio wave reflection plate is a curved surface including an elliptic curve or a curve similar to the elliptic curve except a portion intersecting a straight line passing through two focal points. The wireless communication system according to any one of 1 to 3. 5. A plurality of substantially elliptical radio wave reflection plates are provided, and each substantially elliptical radio wave reflection plate is arranged such that at least one focal point coincides with a focal point of a reflection surface of another approximately elliptical radio wave reflection plate. The wireless communication system according to claim 1, wherein the wireless communication system is a wireless communication system. 6. An interrogator antenna connected to the interrogator, wherein a transponder receives a signal transmitted from one interrogator antenna, and another interrogator receives the signal transmitted from the transponder. The wireless communication system according to claim 1, wherein the wireless communication system receives the signal with an antenna. 7. The wireless communication system according to claim 2, wherein the transponder is arranged in the vicinity of the other focus of the reflecting surface of the substantially elliptical radio wave reflecting plate. 8. The reflection surface of the substantially elliptical radio wave reflection plate includes a part of a spheroidal surface, an elliptic cylindrical surface, or a curved surface similar to these surfaces.
The wireless communication system according to item 1. 9. A plurality of interrogator antennas connected to the interrogator, wherein each interrogator antenna is different after a signal transmitted from each interrogator antenna is reflected by a substantially elliptical radio wave reflection plate. 9. The wireless communication system according to claim 1, wherein the wireless communication system is arranged so as to be focused on an area. 10. The wireless communication system according to claim 1, wherein communication is performed between the interrogator and the moving responder while moving the responder. 11. The interrogator comprises a transmitter for generating the question,
The transmitter is provided separately, and has a receiver that receives a response from the responder.The interrogator antenna has a transmitting interrogator antenna and a receiving interrogator antenna, and the transmitting interrogator antenna is The wireless communication system according to any one of claims 1 to 10, wherein the wireless communication system is connected to a transmitter, and the interrogator antenna for reception is connected to a receiver. 12. The transponder comprises a processing circuit having at least a modulation section and a memory section for accumulating information, and an antenna for transmitting and receiving a signal, and the processing circuit outputs a signal to the signal when the antenna receives the signal. On the basis of the above, according to any one of claims 1 to 11, characterized in that the signal received by the antenna is reflected by changing the reflection characteristic of the antenna by the modulator using the signal related to the information accumulated in the memory. The wireless communication system according to one. 13. The transponder comprises a processing circuit having at least a demodulation section and a memory section for accumulating information, and an antenna for receiving a signal, and the processing circuit outputs a signal to the signal when the antenna receives the signal. 13. The information is written in the memory unit based on the above.
The wireless communication system according to item 1. 14. A non-substantially elliptical radio wave reflection plate formed by a reflection surface having a shape different from a shape including a part of an elliptic curve or a curve similar to the elliptic curve, wherein the transponder has at least a substantially elliptic wave reflection plate and The wireless communication system according to any one of claims 1 to 13, wherein the wireless communication system is capable of communicating with an interrogator via a non-ellipsoidal radio wave reflection plate.