JP2003249872A - Wireless communication system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wireless communication system, which effectively prevents signal scattering and utilizes signals. <P>SOLUTION: A RFID system 1 comprises an interrogator 11, an interrogator antenna 12 connected to the interrogator 11 for transmitting a signal, a radio wave reflection plate 21 for including a parabolic curve or a part of the parabolic curve, which reflects the signal transmitted by the interrogator antenna 12, and a wireless tag 13 for receiving and responding to the signal from the interrogator antenna 12 at least via the radio wave reflection plate 21, to conduct communications with the interrogator 11. A signal, passing through without radiating on the wireless tag 13, is reflected towards the inside of the radio wave reflection plate 21 by the radio wave reflection plate 21. Therefore, signal scattering is prevented, and signals from the interrogator antenna 12 are utilized effectively. <P>COPYRIGHT: (C)2003,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 the focus" includes the focus. In the present invention, the "reflector" includes a reflector having a shape other than the plate shape.

[0003]

2. Description of the Related Art One of wireless communication systems is a mobile identification (RFID) system. The RFID system is composed of an interrogator having a read / write function and a responder that stores and transmits information according to an instruction from the interrogator. The transponder is called a wireless tag. Conventionally, in the micro area, in particular, a tag having a built-in battery has been often used as a wireless tag. Recently, with the progress of semiconductors, a batteryless tag that uses a transmission signal from an interrogator as driving power has appeared, and various applications are being considered in many fields. R
The FID system has a simple configuration, so it is considered to be applied in a wide range of fields such as factory automation, distribution and logistics fields, such as article management in production lines or warehouses, picking systems that automatically sort items, mail delivery, and home delivery. Has been done.

FIG. 16 is a diagram showing the basic configuration of the RFID system 15. The RFID system 15 is the interrogator 1
1, an interrogator antenna 12, and a wireless tag 13. The interrogator antenna 12 is connected to the interrogator 11.

In the RFID system 15, the interrogator 1
The signal from 1 is transmitted to the wireless tag 13 via the interrogator antenna 12. This signal is sent to the wireless tag 1
3 is received, the tag IC (Integr
ated Circuit) is modulated. The modulated signal is transmitted toward the interrogator antenna 12. When this signal is received by the interrogator 11 via the interrogator antenna 12, it is detected by the demodulator in the interrogator 11. In this way, the tag information is retrieved. Further, the RFID system 15 can write and store the information from the interrogator 11 in the wireless tag 13.

[0006] The communication distance between the interrogator antenna 12 and the wireless tag 13 depends on the transmission power of the interrogator 11 and the wireless tag 13.
And the reception sensitivity of the interrogator 11. In the case of a batteryless tag, the communication distance is in the range of several cm to 2 m.

In many RFID systems, a carrier device such as a belt conveyor is installed in front of the interrogator antenna. An object with a wireless tag attached is placed on the carrier. The carrier device moves an object to which the wireless tag is attached. At this time, communication is performed between the interrogator and the wireless tag in a region where the signal from the interrogator antenna is strong.

[0008]

When an object on which a wireless tag is attached is moved by a carrier device for identification, how to extend the communication distance by using a limited transmission power is an important problem.

Since the signal is scattered, the signal becomes weaker as the distance from the interrogator antenna increases, and the communication accuracy between the interrogator and the wireless tag decreases. In addition, the smaller the interrogator antenna, the wider the directional characteristics of the antenna, and the more signals that do not act on the wireless tag. In order to extend the communication distance with limited transmission power, it suffices to eliminate signal scattering and collect signals in a desired area.

Japanese Unexamined Patent Publication (Kokai) No. 5-128289 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 to be connected to each antenna, which increases the cost.

An object of the present invention is to provide a wireless communication system which prevents signal scattering and effectively uses signals.

[0012]

SUMMARY OF THE INVENTION The present invention is directed to an interrogator, an interrogator antenna connected to the interrogator for transmitting a signal, and a parabolic curve or the like that reflects the signal transmitted by the interrogator antenna. And a radio wave reflector formed of a reflecting surface including a part of the curved line, it is possible to receive a signal from the interrogator antenna via at least the radio wave reflector,
A wireless communication system, comprising: a responder for communicating with an interrogator.

According to the present invention, there is provided a radio wave reflector formed of a reflecting surface including a part of a parabolic curve or a curve similar to the parabolic curve that reflects a signal transmitted by an interrogator antenna. Of the signals transmitted from the interrogator antenna, the signals that pass through without being emitted to the responder are reflected by the reflection surface of the radio wave reflection plate inwardly of the reflection surface of the radio wave reflection plate.
A signal whose traveling direction is parallel to the axis of the reflecting surface is focused on the reflecting surface when reflected by the reflecting surface. Therefore, the signal in the vicinity of the focus of the reflecting surface becomes strong. Also, the signal reflected by the reflecting surface after passing through the focal point of the reflecting surface is
Travel parallel to the axis of the reflecting surface. That is, the signal from the interrogator antenna is applied only to the area facing the reflecting surface. Therefore, it is possible to prevent signal scattering. Further, not only the signal directly radiated from the interrogator antenna but also the signal reflected by the radio wave reflection plate, that is, the signal that has passed through once is received by the transponder. Therefore, the signal transmitted by the interrogator antenna can be effectively used.

The present invention is also characterized in that the interrogator antenna is arranged near the focal point of the reflecting surface.

In accordance with the invention, the interrogator antenna is located near the focal point of the reflective surface so that the signal from the interrogator antenna will be parallel to the axis of the reflective surface when reflected by the reflective surface. move on. That is, the signal from the interrogator antenna is applied only to the area facing the reflecting surface. Therefore, even when the interrogator antenna has a low directional characteristic, it is possible to limit the area irradiated with the signal by using the radio wave reflector.

Further, the present invention is characterized in that the transponder is arranged near a focal point of the reflecting surface.

According to the invention, the transponder is located near the focal point of the reflecting surface. A signal whose traveling direction is parallel to the axis of the reflecting surface is focused on the reflecting surface when reflected by the reflecting surface. Therefore, the vicinity of the focal point of the reflecting surface is an area where the signal is strong. By arranging the transponder in this region where the signal is strong, it is possible to increase the communication accuracy between the interrogator and the transponder.

Further, the present invention is characterized in that a plurality of the interrogator antennas are arranged so as to face the reflection surface, and each interrogator antenna is set so as to point near a focal point of the reflection surface. .

According to the present invention, the plurality of interrogator antennas are set so as to face the reflecting surface and direct the vicinity of the focal point of the reflecting surface. In this case, the signal transmitted from the interrogator antenna arranged at a position deviated from the axis of the reflecting surface to the reflecting surface is not parallel to the axis of the reflecting surface, and therefore is reflected by the reflecting surface. , Forms an ambiguous focus at a position different from the focus of the reflecting surface. When there are multiple interrogator antennas, multiple ambiguous focal points are formed. Therefore, it is possible to expand the area where the signal is strong.

Further, according to the present invention, a plurality of the interrogator antennas are arranged near the focal point of the reflecting surface, and the signals transmitted from the respective interrogator antennas are reflected by the reflecting surface and travel in different directions. It is arranged in.

According to the invention, a plurality of interrogator antennas are arranged near the focal point of the reflecting surface. The signal from the interrogator antenna located at a position deviated from the focal point of the reflecting surface is reflected by the reflecting surface, and then radiated to the area deviating from the area facing the reflecting surface.

Further, the present invention is characterized in that the reflecting surface is a paraboloidal curve or a parabolic curve or a parabolic cylinder surface including an intersection of the curve and an axis of the curve and the curve. To do.

According to the invention, the reflecting surface is a paraboloid of revolution or a paraboloid of revolution containing the point of intersection of the parabolic curve or a curve similar thereto with the axis of the curve and said curve. Therefore, the reflecting surface can efficiently collect the signal whose traveling direction is parallel to the axis of the reflecting surface at the focal point of the reflecting surface, and also the signal transmitted to the reflecting surface through the focal point of the reflecting surface. It can be reflected parallel to the axis of the reflecting surface.

According to the present invention, the reflecting surface is a paraboloid of revolution or a paraboloid including a parabolic curve or a curve similar thereto and a portion of the curve deviated from the intersection of the axis of the curve. It is characterized by

According to the present invention, the reflecting surface is a paraboloid of revolution or a paraboloid including a parabolic curve or a curve similar to the parabolic curve and a part of the curve deviating from the intersection of the axis of the curve. . When the signal whose traveling direction is parallel to the axis of the reflecting surface is reflected by the reflecting surface, the signal gathers at the focal point of the reflecting surface at a position deviated from the path through which the interrogator antenna reaches the reflecting surface. Therefore, it is possible to expand the area where the signal is strong.

When the interrogator antenna is provided near the focal point of the reflecting surface, the signal transmitted by the interrogator antenna travels parallel to the axis of the reflecting surface when reflected by the reflecting surface. The path traveled by the signal reflected by the reflecting surface is deviated from the focal point of the reflecting surface, that is, from the interrogator antenna. Therefore, since the interrogator antenna does not shield the signal reflected by the reflecting surface, the signal transmitted by the interrogator antenna can be efficiently applied to the responder.

Further, the present invention is characterized in that a plurality of the interrogator antennas are connected to one interrogator.

According to the invention, a plurality of interrogator antennas are connected to one interrogator. Therefore, when the communication accuracy of each interrogator antenna is different due to an obstacle, it is possible to improve the communication accuracy of the entire system by selecting the information from the interrogator antenna with the highest communication accuracy by the interrogator. .

The present invention is also characterized in that the plurality of interrogator antennas are connected to different interrogators.

According to the present invention, a plurality of interrogator antennas are connected to different interrogators. Therefore,
Since processing is performed in each individual interrogator and the interrogator antenna connected thereto, the processing capacity of the entire system can be enhanced.

Further, in the present invention, another radio wave reflection plate having a reflection surface facing the reflection surface is arranged, and the reflection surface of the other radio wave reflection plate is arranged to reflect an incoming signal to the reflection surface of the other radio wave reflection plate. It is characterized in that the light is reflected near the focal point or in the direction of arrival.

According to the invention, another radio wave reflection plate having a reflection surface facing the reflection surface is arranged. The reflection surface of the other radio wave reflection plate reflects the incoming signal in the vicinity of the focal point of the reflection surface of the other radio wave reflection plate or in the direction of the arrival, so that the signal transmitted from the interrogator antenna is reflected by the radio wave reflection plate. It is possible to prevent scattering outside the sandwiched region. Therefore, the signal from the interrogator antenna can be effectively used. Further, even when the same wireless communication system is arranged side by side, it is possible to prevent signal interference with other wireless communication systems.

According to the present invention, the reflecting surfaces of the two radio wave reflecting plates are rotary paraboloids or paraboloidal cylinders, and the paraboloidal surfaces are arranged so as to face each other. Is disposed near the focal point of the reflection surface of the radio wave reflection plate, and the transponder is disposed at least near the focal point of the reflection surface of the other radio wave reflection plate.

According to the present invention, the reflecting surfaces of the two radio wave reflecting plates, which are the paraboloid of revolution or the parabolic column surface, are arranged so as to face each other with their axes aligned, and the interrogator antenna has one of the radio waves. It is arranged near the focal point of the reflecting surface of the reflector. The signal transmitted from the interrogator antenna to one radio wave reflection plate is reflected by the reflection surface of the one radio wave reflection plate, and travels parallel to the axis of the reflection surface toward the other radio wave reflection plate. This signal is
Since it is reflected again by the reflection surface of the other radio wave reflection plate and focuses on the reflection surface of the other radio wave reflection plate, the vicinity of the focus of the reflection surface of the other radio wave reflection plate may be away from the interrogator antenna. Instead, it becomes an area with a strong signal. Therefore, by disposing the transponder near the focal point of the reflection surface of the other radio wave reflection plate, it is possible to increase the communicable distance between the interrogator antenna and the transponder.

Further, in the present invention, the reflecting surfaces of the two radio wave reflecting plates are rotation paraboloids or paraboloids, which are arranged to face each other with their axes aligned, and two interrogator antennas are provided. The interrogator antennas are arranged near the respective focal points of the reflection surfaces of both radio wave reflection plates.

According to the present invention, the reflecting surfaces of the two radio wave reflecting plates, which are the paraboloid of revolution or the parabolic column surface, are arranged so as to face each other with their axes aligned, and two interrogator antennas are provided. Each interrogator antenna is arranged near the respective focal points of the reflection surfaces of both radio wave reflection plates. The signal transmitted from one interrogator antenna is reflected by the reflection surface of one radio wave reflection plate and travels parallel to the axis toward the other radio wave reflection plate. The signal transmitted from the other interrogator antenna is reflected by the reflecting surface of the other radio wave reflection plate, parallel to the axis,
Proceed toward one radio wave reflector. Therefore, even in a region where communication with the signal from one interrogator antenna is not possible, communication is possible with a signal from the other interrogator antenna. In this way, the communicable area can be expanded.

According to the present invention, the two radio wave reflection plates are
It is characterized in that the respective focal points of the reflecting surfaces are aligned with each other.

According to the present invention, the two radio wave reflection plates are arranged so that the focal points of the respective reflection surfaces are aligned with each other. If the reflecting surfaces of the two radio wave reflectors are a parabolic curve or a curve similar thereto and an intersection point with the axis of the curve and a rotating parabolic surface or a parabolic column surface including the curve, the interrogator antenna transmits. The reflected signal is reflected by one radio wave reflection plate and travels in parallel to the axis toward the other radio wave reflection plate. This signal is
It is reflected again by the reflecting surface of the other radio wave reflection plate and is focused on the focal points of both radio wave reflection plates. Further, this signal travels toward one of the radio wave reflection plates and is reused. Therefore,
The signal transmitted by the interrogator antenna can be effectively used.

Further, in the present invention, the reflection surface of the radio wave reflection plate is a paraboloid of revolution or a paraboloidal surface, and the reflection surface of the other radio wave reflection plate is a circular curve or a part of a curve similar thereto. The radio wave reflector and the other radio wave reflector are arranged so that the focal points of the respective reflection surfaces are aligned with each other.

According to the present invention, a radio wave reflector whose reflection surface is a paraboloid of revolution or a parabolic cylinder surface, and another radio wave reflection whose reflection surface is a curved surface including a part of a circular curve or a curve similar thereto. The plate and the reflecting surface are arranged so that their focal points and centers are aligned with each other. When the signal that has passed through the center of the reflection surface of another radio wave reflection plate is reflected by the reflection surface of the other radio wave reflection plate, it goes toward the direction of arrival, that is, toward the center of the reflection surface of the other radio wave reflection plate. move on. Therefore, the signal near the center of the reflection surface of another radio wave reflection plate, that is, near the focus of the radio wave reflection plate can be strengthened.

Further, in the present invention, the reflection surface of the radio wave reflection plate is a paraboloid of revolution or a paraboloidal surface, and the reflection surface of the other radio wave reflection plate is a flat surface and is reflected by the radio wave reflection plate. It is characterized in that it is arranged orthogonal to the axis of the plane.

According to the present invention, the reflecting surface is orthogonal to the axis of the reflecting surface of the radio wave reflecting plate which is a paraboloid of revolution or a paraboloid.
The reflection surface of another radio wave reflection plate having a flat reflection surface is arranged. The signal transmitted from the interrogator antenna is reflected by the reflection surface of the radio wave reflection plate and travels toward the reflection surface of another radio wave reflection plate. This signal is reflected again on the reflecting surface of another radio wave reflecting plate. Therefore, it is possible to prevent signals from being scattered from a region sandwiched between the radio wave reflection plate and another radio wave reflection plate.

Further, the present invention is characterized in that a plurality of the interrogator antennas are arranged, and the signals transmitted by the interrogator antennas are circularly polarized signals having different turning directions.

According to the present invention, since the signals transmitted from the plurality of interrogator antennas are circularly polarized signals having different turning directions, the signals arriving between the plurality of interrogator antennas have different turning directions. , It is possible to avoid signal interference between the interrogator antennas.

Further, the present invention is characterized by having a device for moving the responder, and performing communication between the interrogator and the moving responder.

According to the present invention, a device for moving the transponder is provided, and communication is performed between the interrogator and the moving transponder in a wide signal strong region. Therefore, the interrogator can communicate with different responders one after another with high communication accuracy.

In the present invention, the transponder comprises a processing circuit having at least a modulation section, a memory section for storing information, and an antenna for transmitting / 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 a signal related to information stored in the memory unit is modulated by the modulator and the antenna is controlled so as to be transmitted from the antenna.

According to the present invention, the transponder has a processing circuit including at least a modulator and a memory unit, and when a signal is received by the antenna, the transponder relates to information stored in the memory unit based on the signal. The signal to be modulated is modulated by the modulator,
Since it controls the antenna to transmit from the antenna,
It is applicable to a readable RFID system.

Further, in the present invention, the transponder comprises at least a demodulation section, a processing circuit having a memory section for accumulating information, and an antenna for receiving a signal, and the processing circuit receives the signal at the antenna. Information is written in the memory portion based on the signal.

According to the present invention, the transponder has a processing circuit including at least a demodulation section and a memory section, and when a signal is received by the antenna, information is written in the memory section based on the signal. It is applicable to possible RFID systems.

[0051]

BEST MODE FOR CARRYING OUT THE INVENTION A wireless communication system includes an interrogator,
It has an interrogator antenna connected to the interrogator and a responder. The interrogator produces a question and the interrogator antenna transmits a signal representative of the question. The transponder receives this signal,
Generate an answer to the question and send a signal representing the answer. The signal from the transponder reaches the interrogator antenna according to the path of the signal from the interrogator antenna. In this way, in the wireless communication system, communication is performed between the interrogator and the responder.

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a configuration of a mobile body identification (RFID) system 1 according to a first embodiment of the present invention. The RFID system 1 includes an interrogator 11, an interrogator antenna 12 connected to the interrogator 11, a wireless tag 13 that is a responder, and a radio wave reflection plate 21 having a reflective surface. In FIG. 1, the radio wave reflection plate 21 is shown in cross section. The reflection surface of the radio wave reflection plate 21 is, for example, a parabolic curve and an intersection of the curve with the axis 20 and a paraboloid of revolution or parabolic surface including the curve. Therefore, a signal whose traveling direction is parallel to the axis 20 of the radio wave reflection plate 21 is
When reflected by the reflection surface of the radio wave reflection plate 21, it is focused on the focal point F of the reflection surface of the radio wave reflection plate 21.

The interrogator 11 includes a question generator for generating a question, a transmission source for generating a carrier wave, a modulator for modulating a signal representing the question with a carrier wave to generate a modulated signal, and a modulator. The signal separator includes a circulator that separates the modulated signal from the signal received by the interrogator antenna 12, and the demodulator that includes a synchronous detector that demodulates the signal received by the interrogator antenna 12. Interrogator 11
Is configured to send the signal modulated by the modulator to the interrogator antenna 12 and receive the signal received by the interrogator antenna 12 from the interrogator antenna 12 to demodulate the demodulator to obtain a response. .

The interrogator antennas 12 are 2 orthogonal to each other.
Two dipole antennas and a phase shifter are provided, and signals are given from the phase shifters to the dipole antennas with a phase difference of 90 degrees from each other, whereby circularly polarized signals can be transmitted. it can. Also, the interrogator antenna 12
In the method, signals obtained from the dipole antennas and having a phase difference of 90 degrees with each other are converted into signals having no phase difference with each other by a phase shifter and then combined. Thereby, it is configured to be able to receive a circularly polarized signal. The interrogator 11 and the interrogator antenna 12 may be integrated.

The interrogator antenna 12 may be an ordinary circular polarization or linear polarization antenna such as a plane antenna.

The interrogator antenna 12 is arranged so as to face the opening surface of the radio wave reflection plate 21. However, the distance between the interrogator antenna 12 and the radio wave reflection plate 21 is equal to
Is greater than the distance between F and its focal point F. Wireless tag 13
Are arranged between the interrogator antenna 12 and the radio wave reflection plate 21.

The signal transmitted from the interrogator antenna 12 is applied to the wireless tag 13 in front of the interrogator antenna 12. Signals that have not passed through the wireless tag 13 and have passed through are reflected by the radio wave reflection plate 21. The reflected signal is focused on the focal point F of the radio wave reflection plate 21.

In this way, the signal passing through the wireless tags 13 is reflected by the radio wave reflection plate 21, so that the signal is prevented from being scattered and the signal is effectively used. In addition, the radio wave reflector 2
Since the signal reflected at 1 is collected at the focal point F of the radio wave reflecting plate 21, the signal near the focal point F of the radio wave reflecting plate 21 becomes strong. The term “near” means a range in which the wireless tag 13 can respond to a question from the interrogator for response processing. Therefore, the reception sensitivity is high between the interrogator 11 and the wireless tag 13 near the focal point F of the radio wave reflection plate 21, and the communication accuracy representing the accuracy of the transfer of information to be communicated increases.

FIG. 2 is a diagram showing a typical example of the wireless tag 13, FIG. 2 (a) is a plan view of the wireless tag 13a which mainly transmits and receives linearly polarized signals, and FIG. 2 is a plan view of the wireless tag 13b that transmits and receives circularly polarized signals to and from FIG.
(C) is sectional drawing seen from the cutting plane line I-I of the wireless tag 13b.

The wireless tag 13a shown in FIG.
On a flat dielectric substrate 30, a dipole antenna 31 and a tag IC (Integrated Circuit) 3 which is a processing circuit.
2 is a mounted tag. The tag IC 32 has a demodulation unit, a modulation unit, and a memory unit that stores information. The tag IC 32 demodulates the signal received by the dipole antenna 31 by the demodulation unit. When the demodulated signal represents a response command, the tag IC 32 modulates the signal related to the information stored in the memory unit by the modulator based on the command, and transmits the modulated signal from the dipole antenna 31. The dipole antenna 32 is controlled. If the demodulated signal represents a write command, the tag IC 32 writes the specified information in the memory unit. The tag IC 32 does not need to have the function corresponding to both the response command and the write command, and may have only the function corresponding to the response command.

The wireless tag 13b shown in FIGS. 2 (a) and 2 (c) is filed by the applicant of the present application in Japanese Patent Application No. 2001-1573.
It is a wireless tag proposed as 08. The wireless tag 13b includes a radiation surface 34 formed on one surface of a flat dielectric substrate 30, a ground surface 35 formed on the other surface of the dielectric substrate 30, a radiation surface 34 and a ground surface. 35 and a tag IC 32 electrically connected to 35. In the present embodiment, a composite tag in which two wireless tags 13b having different left-handed and right-handed are bonded together is also effective.

The wireless tag 13 is preferably a tag which can communicate from both sides, such as a composite tag using the wireless tag 13a and the wireless tag 13b.

When the signal transmitted by the interrogator antenna 12 is a linearly polarized signal, the wireless tag 13a is used, and when it is a circularly polarized signal, the wireless tag 13b is used.

FIG. 3 shows the second embodiment R of the present invention.
It is a figure which shows the structure of the FID system 2. The RFID system 2 includes an interrogator 11, interrogator antennas 12 a, 12 b and 12 c connected to the interrogator 11, and a wireless tag 13.
And a radio wave reflection plate 21. The wireless tag 13 of the present embodiment has the same configuration as the wireless tag 13 of the first embodiment described above, and therefore its description is omitted. The reflection surface of the radio wave reflection plate 21 is, for example, a parabolic curve and an intersection of the curve with the axis 20 and a paraboloid of revolution or parabolic surface including the curve. Therefore, a signal whose traveling direction is parallel to the axis 20 of the radio wave reflection plate 21 is focused on the focus F of the radio wave reflection plate 21 when reflected by the radio wave reflection plate 21. A signal whose traveling direction is slightly inclined with respect to the axis 20 of the radio wave reflection plate 21 is reflected by the radio wave reflection plate 21 to form an ambiguous focus at a different position near the focus F of the radio wave reflection plate 21.

Interrogator antennas 12a, 12b, 12c
Are arranged so as to face the opening surface of the radio wave reflection plate 21. However, the distance between the interrogator antennas 12a, 12b, 12c and the radio wave reflection plate 21 is determined by the radio wave reflection plate 21 and its focal point F.
Greater than the distance between. Interrogator antennas 12a, 12
b and 12c are set so as to be directed near the focal point F of the radio wave reflection plate 21. The wireless tag 13 is the interrogator antenna 1
It is arranged between 2a, 12b, 12c and the radio wave reflection plate 21.

The signals from the interrogator antennas 12a, 12b, 12c may be time-divided and transmitted, or may be transmitted simultaneously.

The signals transmitted from the interrogator antennas 12a, 12b, 12c are the interrogator antennas 12a, 12b,
The wireless tag 13 in front of 12c is illuminated. Signals that have not passed through the wireless tag 13 and passed through are transmitted by the radio wave reflection plate 2
Reflected by 1. The reflected signals gather at the focal point F of the radio wave reflection plate 21 and different positions near the focal point F.

In this way, the signal passing through the wireless tags 13 is reflected by the radio wave reflection plate 21, so that the signal is prevented from being scattered and the signal is effectively used. The signals reflected by the radio wave reflection plate 21 are collected at the focus F of the radio wave reflection plate 21 and different positions near the focus F. Therefore, as compared with the RFID system 1 according to the first embodiment described above, a strong signal region is formed wider and a communicable region is expanded. Further, when the interrogator antennas 12a, 12b, 12c have different communication accuracies due to obstacles,
By selecting the information from the interrogator antenna with the highest communication accuracy by the interrogator 11, the communication accuracy of the RFID system 2 as a whole is increased.

In the RFID system 2, the interrogator antennas 12a, 12b, 12c are connected to one interrogator 11, but may be connected to different interrogators. For example, interrogators 11a and 11c having the same configuration as the interrogator 11 are provided, the interrogator antenna 12a is provided in the interrogator 11a, the interrogator antenna 12b is provided in the interrogator 11,
The interrogator antenna 12c may be connected to the interrogator 11c. In this case, processing can be performed in each interrogator, so that the processing capability of the entire system can be increased. Also, the interrogator antennas 12a, 12
The signal formats transmitted by b and 12c may be different. For example, when a left-handed circular polarization tag and a right-handed circular polarization tag are used together as the wireless tag 13, the interrogator antennas 12a and 12b transmit left-handed circular polarization signals and the interrogator antenna 12c rotates right. Circularly polarized signals may be transmitted. In this case, the direction is reversed and the interrogator antenna 12a,
Even a right-handed circularly polarized wave tag that cannot communicate with the left-handed circularly polarized wave signal transmitted by 12b can communicate with the right-handed circularly polarized wave signal transmitted by the interrogator antenna 12c.

FIG. 4 shows R which is the third embodiment of the present invention.
It is a figure which shows the structure of the FID system 3. In the present embodiment, parts having the same configurations as those of the first embodiment described above are designated by the same reference numerals, and description thereof will be omitted. The RFID system 3 includes an interrogator 11, an interrogator antenna 12 connected to the interrogator 11, a wireless tag 13, and a radio wave reflection plate 21.
With. The reflection surface of the radio wave reflection plate 21 has a parabolic curve,
It is a paraboloid of revolution or a paraboloidal surface including the intersection of the curve with the axis 20 and the curve.

The interrogator antenna 12 is arranged near the focal point F of the radio wave reflection plate 21 so as to face the opening surface of the radio wave reflection plate 21. The wireless tag 13 is arranged between the interrogator antenna 12 and the radio wave reflection plate 21, on the opposite side of the radio wave reflection plate 21 with the interrogator antenna 12 in between, or on both of them.

The signal transmitted from the interrogator antenna 12 is applied to the wireless tag 13 in front of the interrogator antenna 12. Signals that have not passed through the wireless tag 13 and have passed through are reflected by the radio wave reflection plate 21. The reflected signal travels parallel to the axis 20 of the radio wave reflection plate 21. When the wireless tag 13 does not exist between the focal point F and the radio wave reflection plate 21, the signal enhancement by the radio wave reflection plate 21 is equivalent to the gain G obtained by the parabolic antenna, and G = 4πA / λ.
² (A is the aperture area, λ is the wavelength of the radio wave).

As described above, since the signal passing through the wireless tags 13 is reflected by the radio wave reflection plate 21, the area to which the signal is irradiated is limited. That is, signal scattering is prevented and the signal is effectively used.

In the RFID system 3, the number of interrogator antennas is not limited to one, and another interrogator antenna 12a may be additionally provided at a position shown by a virtual line in FIG. 4, for example. In this case, the interrogator antennas are arranged so that the signals transmitted from the individual interrogator antennas are reflected by the radio wave reflection plate 21 and travel in different directional directions to illuminate different areas. As a result, the communicable area is expanded as compared with the case of one interrogator antenna. The plurality of interrogator antennas may be connected to one interrogator or may be connected to different interrogators. In any case, the signals from the plurality of interrogator antennas may be time-divided and may be transmitted at the same time.

FIG. 5 shows the R of the fourth embodiment of the present invention.
It is a figure which shows the structure of the FID system 4. In the present embodiment, parts having the same configurations as those of the first embodiment described above are designated by the same reference numerals, and description thereof will be omitted. The RFID system 4 includes an interrogator 11, an interrogator antenna 12 connected to the interrogator 11, a wireless tag 13, and a radio wave reflection plate 22.
And a transport device 16. The reflection surface of the radio wave reflection plate 22 is a parabolic curve or a paraboloid of revolution including a parabolic curve and a portion of the curve deviated from the intersection with the axis 20.

The interrogator antenna 12 is arranged so as to face the opening surface of the radio wave reflection plate 22. The wireless tag 13 is arranged in the traveling path of the signal. The wireless tag 13 is the carrier device 1.
6 is moved in the direction of arrow A.

The signal transmitted from the interrogator antenna 12 is applied to the wireless tag 13 in front of the interrogator antenna 12. Signals that have not passed through the wireless tag 13 and have passed through are reflected by the radio wave reflection plate 22. The reflected signal is focused on the focal point F of the radio wave reflection plate 22. However, the focal point F is located at a position deviated from the path through which the signal from the interrogator antenna 12 passes before reaching the radio wave reflection plate 22.

In this way, the signal passing through the wireless tags 13 is reflected by the radio wave reflection plate 22, so that the signal is prevented from being scattered and the signal is effectively used. The signal reflected by the radio wave reflection plate 22 is transmitted to the interrogator antenna 1
The signal from 2 collects in the vicinity of the focal point F at a position deviated from the path through which the signal reaches the radio wave reflection plate 22. Therefore, the area where the signal is strong is wider than that of the RFID system 1, and the communicable area is expanded.

The position of the interrogator antenna 12 may be near the focus F of the radio wave reflection plate 22. In this case, the interrogator antenna 12 does not block the signal reflected by the radio wave reflection plate 22. Therefore, the signal transmitted by the interrogator antenna 12 is efficiently applied to the wireless tag 13.

In the RFID system 4, when a plurality of interrogator antennas are provided and signals are transmitted from the interrogator antennas, the area where the signal is strong is expanded as compared with the case where there is one interrogator antenna. The plurality of interrogator antennas may be connected to one interrogator or may be connected to different interrogators. In any case, the signals from the plurality of interrogator antennas may be time-divided and may be transmitted at the same time.

FIG. 6 is a front view of the radio wave reflection plate 21. The radio wave reflection plate 21 is, as shown in FIG.
The parabolic surface may be a paraboloid that has an elliptical shape when viewed from the front, or may have a substantially rectangular shape when viewed from the front, as shown in FIG. 6B. It may be.

The radio wave reflection plate may be a curved surface including a part of a curve similar to a parabolic curve, instead of a part such as a paraboloid of revolution or a parabolic column surface.

FIG. 7 is a perspective view of the radio wave reflection plate 23 which is a parabolic column surface. The interrogator antenna 12 is arranged so as to face the radio wave reflection plate 23. Although not shown, the wireless tag 13
Are arranged between the interrogator antenna 12 and the radio wave reflection plate 23.

The radio wave reflection plate may be a curved surface similar to a parabolic column surface instead of a parabolic column surface. FIG. 8: is a figure which shows the structure of the RFID system 5 which is the 5th Embodiment of this invention. In the present embodiment, parts having the same configurations as those of the first embodiment described above are designated by the same reference numerals, and description thereof will be omitted. The RFID system 5 includes an interrogator 11, an interrogator antenna 12 connected to the interrogator 11, and a wireless tag 1.
3 and radio wave reflection plates 21a and 21b. The reflection surfaces of the radio wave reflection plates 21a and 21b are parabolic curves, intersections of the axes of the curves, and rotation paraboloids or parabolic column surfaces including the curves. For example, the radio wave reflection plates 21a and 21b
The reflective surface of is a parabolic surface cut out symmetrically with respect to the axis.

The radio wave reflection plates 21a and 21b are arranged to face each other with their axes aligned. These radio wave reflection plates 21a and 21b
The wireless tag 13 is arranged in the area sandwiched between. The interrogator antenna 12 is arranged near the focal point F of the one radio wave reflection plate 21a so as to face the opening surface of the one radio wave reflection plate 21a.

The signal transmitted from the interrogator antenna 12 is reflected by one of the radio wave reflection plates 21a, and the radio wave reflection plate 2
The other radio wave reflection plate 2 is parallel to the axes of 1a and 21b.
Go towards 1b. This signal is transmitted to the other radio wave reflection plate 2
1b is reflected again, and the focus F of the other radio wave reflection plate 21b is reflected.
Gather in.

As described above, the signal passing through the wireless tag 13 is reflected by the radio wave reflection plates 21a and 21b. Therefore, it is possible to prevent the signal from being scattered outside the area sandwiched between the radio wave reflection plates 21a and 21b, and to effectively use the signal. Further, it is possible to improve signal interference with other systems.

The signal reflected by the other radio wave reflection plate 21b is focused on the focus F of the other radio wave reflection plate 21b. Therefore, the vicinity of the focal point F of the other radio wave reflection plate 21b is a strong signal region even though it is far from the interrogator antenna 12.

In the RFID system 5, the other radio wave reflection plate 21b is provided near the focus F of the other radio wave reflection plate 21b.
Facing the opening surface of the other interrogator antenna 12a
May be provided. In this case, even in a region in which the signal from the interrogator antenna 12 cannot communicate, it becomes a region in which the signal from another interrogator antenna 12a enables communication. In this way, the communicable area can be expanded. Further, for example, when a right-hand circularly polarized signal is transmitted from the interrogator antenna 12 and a left-hand circularly polarized signal is transmitted from another interrogator antenna 12a, signal interference between the interrogator antennas can be avoided. You can

FIG. 9 shows R which is the sixth embodiment of the present invention.
It is a figure which shows the structure of the FID system 6. In the present embodiment, parts having the same configurations as those of the first embodiment described above are designated by the same reference numerals, and description thereof will be omitted. The RFID system 6 includes an interrogator 11, an interrogator antenna 12 connected to the interrogator 11, a wireless tag 13, and a radio wave reflection plate 22.
a and 22b. The reflection surfaces of the radio wave reflection plates 22a and 22b are paraboloidal curved surfaces, paraboloidal curved surfaces, and the like including the curved portion of the parabolic curve and the portion deviated from the intersection of the curve and the axis.

The radio wave reflection plates 22a and 22b are arranged to face each other with their axes aligned. These radio wave reflection plates 22a and 22b
The wireless tag 13 is arranged in the area sandwiched between. The interrogator antenna 12 is arranged near the focal point F of the one radio wave reflection plate 22a so as to face the one radio wave reflection plate 22a.

The signal transmitted from the interrogator antenna 12 is reflected by one of the radio wave reflection plates 22a, and the radio wave reflection plate 2
The other radio wave reflection plate 2 is parallel to the axes of 2a and 22b.
Go towards 2b. This signal is transmitted to the other radio wave reflection plate 2
2b again, and the focus F of the other radio wave reflection plate 22b.
Gather in.

The focal point F of one radio wave reflection plate 22a exists outside the region sandwiched by the radio wave reflection plates 22a and 22b,
The interrogator antenna 12 has a focus F of the radio wave reflection plate 22a.
Is located in. Therefore, the interrogator antenna 12 does not block the signal reflected by the one radio wave reflection plate 22a, that is, the signal traveling between the radio wave reflection plates 22a and 22b. Therefore, the signal transmitted by the interrogator antenna 12 is efficiently applied to the wireless tag 13.

In the RFID system 6, the other radio wave reflection plate 22b is provided near the focus F of the other radio wave reflection plate 22b.
Facing the opening surface of the other interrogator antenna 12a
May be provided. In this case, even in a region in which the signal from the interrogator antenna 12 cannot communicate, it becomes a region in which the signal from another interrogator antenna 12a enables communication. In this way, the communicable area can be expanded.

FIG. 10 is a diagram showing the configuration of the RFID system 7 according to the seventh embodiment of the present invention. In the present embodiment, parts having the same configurations as those of the first embodiment described above are designated by the same reference numerals, and description thereof will be omitted. RFID
The system 7 includes an interrogator 11, an interrogator antenna 12 connected to the interrogator 11, a wireless tag 13, and a radio wave reflection plate 2.
1 and 22 are provided. The reflection surface of one radio wave reflection plate 21 is a parabolic curve, a point of intersection with the axis of the curve and a paraboloid of revolution or parabolic surface including the curve, and the reflection surface of the other radio wave reflection plate 22. Is a parabolic surface including a part of the parabolic curve that is displaced from the intersection of the curve and the axis of the curve.

The radio wave reflection plates 21 and 22 are arranged so as to face each other. The wireless tag 13 is arranged in the area sandwiched between the radio wave reflection plates 21 and 22. The interrogator antenna 12 is arranged near the focus F of the other radio wave reflection plate 22 so as to face the radio wave reflection plate 22.

The signal transmitted from the interrogator antenna 12 is reflected by the other radio wave reflection plate 22, and the radio wave reflection plate 2
Traveling toward one of the radio wave reflection plates 21 parallel to the axes of 1 and 22. This signal is reflected again by the radio wave reflection plate 21 on one side and is focused on the focal point F of the radio wave reflection plate 21 on one side.

The signal transmitted by the interrogator antenna 12 travels without being shielded by the interrogator antenna 12, and is focused on the focal point F of one of the radio wave reflection plates 21. That is, the signal transmitted by the interrogator antenna 12 efficiently gathers at the focal point F of the radio wave reflection plate 21.

In the RFID system 7, another interrogator antenna 12a may be provided near the focal point F of one radio wave reflection plate 21 so as to face the opening surface of the radio wave reflection plate 21.

FIG. 11 is a diagram showing the configuration of the RFID system 8 according to the eighth embodiment of the present invention. In the present embodiment, parts having the same configurations as those of the first embodiment described above are designated by the same reference numerals, and description thereof will be omitted. RFID
The system 8 includes an interrogator 11, an interrogator antenna 12 connected to the interrogator 11, a wireless tag 13, and a radio wave reflection plate 2.
2, 24 and. The reflection surface of one of the radio wave reflection plates 22 is a paraboloid of revolution or a paraboloid including a parabolic curve and a portion of the curve deviated from the intersection with the axis of the curve. The reflection surface of the other radio wave reflection plate 24 is flat.

The other radio wave reflection plate 24 is arranged opposite to the one radio wave reflection plate 22 and orthogonal to the axis of the one radio wave reflection plate 22. The wireless tag 13 is arranged in the area sandwiched between the radio wave reflection plates 22 and 24. Interrogator antenna 12
Is arranged near the focal point F of one radio wave reflection plate 22 so as to face the one radio wave reflection plate 22.

The signal transmitted from the interrogator antenna 12 is reflected by one of the radio wave reflection plates 22 and travels in parallel to the axis of the one radio wave reflection plate 22 toward the other radio wave reflection plate 24. This signal is reflected again by the other radio wave reflection plate 24.

As described above, by reflecting the signals by the radio wave reflection plates 22 and 24, it is possible to prevent the signals from being scattered and to effectively use the signals.

FIG. 12 is a diagram showing the configuration of the RFID system 9 according to the ninth embodiment of the present invention. In the present embodiment, parts having the same configurations as those of the first embodiment described above are designated by the same reference numerals, and description thereof will be omitted. RFID
The system 9 includes an interrogator 11, an interrogator antenna 12 connected to the interrogator 11, a wireless tag 13, and a radio wave reflection plate 2.
1, 24. The reflection surface of one of the radio wave reflection plates 21 is a parabolic curve, a point of intersection with the axis of the curve, and a rotating parabolic surface or a parabolic cylindrical surface including the curve. The reflection surface of the other radio wave reflection plate 24 is flat.

The other radio wave reflection plate 24 is arranged opposite to the one radio wave reflection plate 21 and orthogonal to the axis of the one radio wave reflection plate 21. The wireless tag 13 is arranged in the area sandwiched between the radio wave reflection plates 21 and 24. Interrogator antenna 12
Is arranged near the focal point F of one radio wave reflection plate 21 so as to face the one radio wave reflection plate 21.

The signal transmitted from the interrogator antenna 12 is reflected by one of the radio wave reflection plates 21 and travels in parallel to the axis of the one radio wave reflection plate 21 toward the other radio wave reflection plate 24. This signal is reflected again by the other radio wave reflection plate 24.

As described above, by reflecting the signal by the radio wave reflection plates 21 and 24, it is possible to prevent the signal from being scattered and to effectively use the signal.

FIG. 13 is a diagram showing the configuration of the RFID system 10 according to the tenth embodiment of the present invention. In the present embodiment, parts having the same configurations as those of the first embodiment described above are designated by the same reference numerals, and description thereof will be omitted. RF
The ID system 10 includes an interrogator 11, an interrogator antenna 12 connected to the interrogator 11, a wireless tag 13, and radio wave reflection plates 22 and 25. The reflection surface of one radio wave reflection plate 22 is a paraboloid of revolution or a paraboloid including a parabolic curve and a part of the curve deviated from the intersection with the axis of the curve. The reflection surface of the other radio wave reflection plate 25 is a curved surface including a part of a circular curve.

The other radio wave reflection plate 25 is arranged so as to face the one radio wave reflection plate 22 and be centered around the focal point F of the one radio wave reflection plate 22. Radio wave reflector 2
The wireless tag 13 is arranged in the area sandwiched between the two and 25. The interrogator antenna 12 is arranged so that the traveling direction of the signal to be transmitted is parallel to the axis of one radio wave reflection plate 22.
It is arranged so as to face one of the radio wave reflection plates 22.

The signal transmitted from the interrogator antenna 12 is reflected by one of the radio wave reflection plates 22, once gathered at the focal point F of the one radio wave reflection plate 22, and then separated and travels toward the other radio wave reflection plate 25. . This signal is reflected again by the other radio wave reflection plate 25 and is focused on the focus F of the one radio wave reflection plate 22. Therefore, the vicinity of the focal point F of the one radio wave reflection plate 22 is an area where the signal is strong.

FIG. 14 is a diagram showing the configuration of the RFID system 50 according to the eleventh embodiment of the present invention. The RFID system 50 according to the present embodiment is similar to the RFID system 5 according to the fifth embodiment described above, except that the radio wave reflection plates 21a,
This is an example in which the respective focal points F of 1b are aligned and arranged.

The signal transmitted from the interrogator antenna 12 is reflected by one radio wave reflection plate 21a and travels in parallel to the axis toward the other radio wave reflection plate 21b. This signal is reflected again by the other radio wave reflection plate 21b and gathers at the focal point F of the radio wave reflection plates 21a and 21b. Further, this signal travels toward one of the radio wave reflection plates 21a. Therefore, the signal transmitted by the interrogator antenna 12 can be effectively used.

A plurality of interrogator antennas may be provided in the RFID systems 5 to 10, 50. When a plurality of interrogator antennas are provided and signals are transmitted from the respective interrogator antennas, the area where the signal is strong is expanded as compared with the case where there is one interrogator antenna. The plurality of interrogator antennas may be connected to one interrogator or may be connected to different interrogators. In any case, the signals from the plurality of interrogator antennas may be time-divided and transmitted,
It may be transmitted at the same time.

FIG. 15 is a perspective view of the RFID system 7. However, in FIG. 15, the transport device 16 omitted in FIG. 10 is also shown. The wireless tag 13 is attached to the object 17.

Object 17 to which wireless tag 13 is attached
Is moved in the direction of arrow B by the transport device 16. The moving direction of the object 17 may be the direction opposite to the direction of the arrow B. When the object 17 passes through the area sandwiched between the radio wave reflection plates 21 and 22 and the vicinity of the interrogator antenna 12,
Efficient communication is performed between the interrogator 11 and the wireless tag 13. By arranging the objects 17 on the carrier device 16 side by side in the direction of the arrow B and operating the carrier device 16 continuously, the interrogator 11 can communicate with the wireless tags 13 one after another.

Although not shown, in order to prevent signal scattering,
A metal body or an absorber may be arranged around the radio wave reflection plates 21 and 22.

In the embodiment of the configuration using a plurality of interrogator antennas among the above-mentioned respective embodiments, the signal transmitted from the interrogator antenna is received by the wireless tag directly or through the radio wave reflection plate, The signal from the wireless tag may be received by the same interrogator antenna, either directly or via a radio wave reflector.

Further, in the radio communication system using the radio wave reflecting plate as in the present invention, the propagation direction of the signal can be changed by reflecting the signal with the radio wave reflecting plate.
Therefore, one interrogator antenna is used as a transmission-only interrogator antenna, and another interrogator antenna is used as a reception-only interrogator antenna. May be received by the wireless tag directly or via the radio wave reflection plate, and the signal from the wireless tag may be received by the interrogator antenna for reception only directly or via the radio wave reflection plate.

By separately providing an interrogator antenna dedicated to transmission and an interrogator antenna dedicated to reception, the radio tag and the interrogator antenna dedicated to reception can be arranged at positions with high reception sensitivity, respectively, and communication accuracy is improved. Can be higher. Therefore, the degree of freedom in selecting the layout of the entire wireless communication system is increased. Further, by making transmission / reception of the interrogator antenna dedicated, demodulation processing of signals in the interrogator is simplified. When the transmission / reception is dedicated, each interrogator antenna may be commonly connected to one interrogator or may be connected to different interrogators.

When each interrogator antenna is connected to a different interrogator, the cable connecting each interrogator antenna and the interrogator can be shortened, and the cable loss can be reduced. In the above-described embodiments, the interrogator may be configured to be able to generate a question and an answer, and may be a transmitter that generates a question and a receiver that generates an answer. Alternatively, the interrogator antenna dedicated to transmission may be connected to the transmitter and the interrogator antenna dedicated to reception may be connected to the receiver. In this way, the transmitting and receiving functions of the interrogator may be separated.

Although the RFID system has been described in each of the above embodiments, the present invention can be applied to a wireless communication system such as Bluetooth and a wireless LAN (Local Area Network).

[0122]

As described above, according to the present invention, there is provided a radio wave reflector formed of a reflecting surface including a part of a parabolic curve or a curve similar to the parabolic curve that reflects a signal transmitted by an interrogator antenna. . Of the signals transmitted from the interrogator antenna, the signals that pass through without being emitted to the responder are reflected by the reflection surface of the radio wave reflection plate inwardly of the reflection surface of the radio wave reflection plate. A signal whose traveling direction is parallel to the axis of the reflecting surface is focused on the reflecting surface when reflected by the reflecting surface. Therefore, the signal in the vicinity of the focus of the reflecting surface becomes strong. Further, the signal reflected by the reflecting surface after passing through the focal point of the reflecting surface proceeds parallel to the axis of the reflecting surface. That is, the signal from the interrogator antenna is applied only to the area facing the reflecting surface. Therefore, it is possible to prevent signal scattering. Further, not only the signal directly radiated from the interrogator antenna but also the signal reflected by the radio wave reflection plate, that is, the signal that has passed through once is received by the transponder. Therefore, the signal transmitted by the interrogator antenna can be effectively used.

According to the present invention, the interrogator antenna is
Being located near the focal point of the reflecting surface, the signal from the interrogator antenna travels parallel to the axis of the reflecting surface when reflected by the reflecting surface. That is, the signal from the interrogator antenna is applied only to the area facing the reflecting surface. Therefore, even when the interrogator antenna has a low directional characteristic, it is possible to limit the area irradiated with the signal by using the radio wave reflector.

Further, according to the present invention, the transponder is arranged near the focal point of the reflecting surface. A signal whose traveling direction is parallel to the axis of the reflecting surface is focused on the reflecting surface when reflected by the reflecting surface. Therefore, the vicinity of the focal point of the reflecting surface is an area where the signal is strong. By arranging the transponder in this region where the signal is strong, it is possible to increase the communication accuracy between the interrogator and the transponder.

Further, according to the present invention, the plurality of interrogator antennas are set so as to face the reflecting surface and direct the vicinity of the focal point of the reflecting surface. In this case, the signal transmitted from the interrogator antenna arranged at a position deviated from the axis of the reflecting surface to the reflecting surface is not parallel to the axis of the reflecting surface, and therefore is reflected by the reflecting surface. , Forms an ambiguous focus at a position different from the focus of the reflecting surface. When there are multiple interrogator antennas, multiple ambiguous focal points are formed. Therefore, it is possible to expand the area where the signal is strong.

Further, according to the present invention, a plurality of interrogator antennas are arranged near the focal point of the reflecting surface. The signal from the interrogator antenna located at a position deviated from the focal point of the reflecting surface is reflected by the reflecting surface, and then radiated to the area deviating from the area facing the reflecting surface.

Further, according to the present invention, the reflecting surface is a paraboloid of revolution or a paraboloid of revolution including the intersection of the parabolic curve or a curve similar thereto and the axis of the curve and the curve. Therefore, the reflective surface can efficiently collect signals whose traveling direction is parallel to the axis of the reflective surface at the focal point of the reflective surface,
Further, it is possible to reflect the signal transmitted through the focal point of the reflecting surface and transmitted to the reflecting surface in parallel to the axis of the reflecting surface.

Further, according to the present invention, the reflecting surface is a paraboloid of revolution or a parabolic cylinder including a parabolic curve or a curve similar thereto and a portion of the curve deviated from the intersection of the axis of the curve. is there. A signal whose traveling direction is parallel to the axis of the reflecting surface is
When reflected by the reflecting surface, it is focused on the focal point of the reflecting surface at a position deviated from the path passed from the interrogator antenna to the reflecting surface. Therefore, it is possible to expand the area where the signal is strong.

When the interrogator antenna is provided near the focal point of the reflecting surface, the signal transmitted by the interrogator antenna advances parallel to the axis of the reflecting surface when reflected by the reflecting surface. The path traveled by the signal reflected by the reflecting surface is deviated from the focal point of the reflecting surface, that is, from the interrogator antenna. Therefore, since the interrogator antenna does not shield the signal reflected by the reflecting surface, the signal transmitted by the interrogator antenna can be efficiently applied to the responder.

Further, according to the present invention, a plurality of interrogator antennas are connected to one interrogator. Therefore, if the communication accuracy of each interrogator antenna is different due to obstacles,
By selecting the information from the interrogator antenna with the highest communication accuracy by the interrogator, the communication accuracy of the entire system can be increased.

Further, according to the present invention, a plurality of interrogator antennas are connected to different interrogators. Therefore, since processing is performed in each interrogator and interrogator antenna connected to each interrogator, the processing capability of the entire system can be enhanced.

Further, according to the present invention, another radio wave reflection plate having a reflection surface facing the reflection surface is arranged. The reflection surface of the other radio wave reflection plate reflects the incoming signal in the vicinity of the focal point of the reflection surface of the other radio wave reflection plate or in the direction of the arrival, so that the signal transmitted from the interrogator antenna is reflected by the radio wave reflection plate. It is possible to prevent scattering outside the sandwiched region. Therefore, the signal from the interrogator antenna can be effectively used. Further, even when the same wireless communication system is arranged side by side, it is possible to prevent signal interference with other wireless communication systems.

Further, according to the present invention, the reflecting surfaces of the two radio wave reflecting plates, which are a rotating parabolic surface or a parabolic cylindrical surface, are arranged to face each other with their axes aligned, and the interrogator antenna of either one of them is arranged. It is arranged near the focal point of the reflection surface of the radio wave reflection plate. The signal transmitted from the interrogator antenna to one radio wave reflection plate is reflected by the reflection surface of the one radio wave reflection plate, and travels parallel to the axis of the reflection surface toward the other radio wave reflection plate. This signal is reflected again on the reflection surface of the other radio wave reflection plate and is focused on the focus of the reflection surface of the other radio wave reflection plate. However, it is a strong signal area. Therefore, by disposing the transponder near the focal point of the reflection surface of the other radio wave reflection plate, it is possible to increase the communicable distance between the interrogator antenna and the transponder.

Further, according to the present invention, the reflecting surfaces of the two radio wave reflecting plates, which are a rotating parabolic surface or a parabolic pillar surface, are arranged to face each other with their axes aligned, and two interrogator antennas are provided. , The interrogator antennas are arranged near the focal points of the reflection surfaces of both radio wave reflection plates. The signal transmitted from one interrogator antenna is reflected by the reflection surface of one radio wave reflection plate and travels parallel to the axis toward the other radio wave reflection plate. The signal transmitted from the other interrogator antenna is reflected by the reflection surface of the other radio wave reflection plate and travels parallel to the axis toward the one radio wave reflection plate. Therefore, even in a region where communication with the signal from one interrogator antenna is not possible, communication is possible with a signal from the other interrogator antenna. In this way, the communicable area can be expanded.

Further, according to the present invention, the two radio wave reflection plates are arranged so that the focal points of the respective reflection surfaces are aligned with each other. If the reflecting surfaces of the two radio wave reflectors are a parabolic curve or a curve similar thereto and an intersection point with the axis of the curve and a rotating parabolic surface or a parabolic column surface including the curve, the interrogator antenna transmits. The reflected signal is reflected by one radio wave reflection plate and travels in parallel to the axis toward the other radio wave reflection plate. This signal is reflected again by the reflecting surface of the other radio wave reflection plate and is focused on the focal points of both radio wave reflection plates. Further, this signal travels toward one of the radio wave reflection plates and is reused. Therefore, the signal transmitted by the interrogator antenna can be effectively used.

According to the present invention, a radio wave reflector whose reflection surface is a paraboloid of revolution or a parabolic pillar surface, and another radio wave whose reflection surface is a curved surface including a part of a circular curve or a curve similar thereto. The reflector and the reflector are arranged so that their focal points and centers are aligned with each other. When the signal that has passed through the center of the reflection surface of another radio wave reflection plate is reflected by the reflection surface of the other radio wave reflection plate, it goes toward the direction of arrival, that is, toward the center of the reflection surface of the other radio wave reflection plate. move on. Therefore, the signal near the center of the reflection surface of another radio wave reflection plate, that is, near the focus of the radio wave reflection plate can be strengthened.

Further, according to the present invention, the reflection surface is orthogonal to the axis of the reflection surface of the radio wave reflection plate whose surface is a paraboloid of revolution or a parabolic surface, and the reflection surface is reflected by another radio wave reflection plate having a planar shape. The faces are placed. The signal transmitted from the interrogator antenna is reflected by the reflection surface of the radio wave reflection plate and travels toward the reflection surface of another radio wave reflection plate. This signal is reflected again on the reflecting surface of another radio wave reflecting plate. Therefore, it is possible to prevent signals from being scattered from a region sandwiched between the radio wave reflection plate and another radio wave reflection plate.

Further, according to the present invention, since the signals transmitted from the plurality of interrogator antennas are circularly polarized signals having different turning directions, the signals arriving between the plurality of interrogator antennas have different turning directions. Differently, it is possible to avoid signal interference between the interrogator antennas.

Further, according to the present invention, a device for moving the responder is provided, and communication is performed between the interrogator and the moving responder in a wide signal strong region. Therefore, the interrogator can communicate with different responders one after another with high communication accuracy.

Further, according to the present invention, the transponder has a processing circuit including at least a modulator and a memory, and when a signal is received by the antenna, information stored in the memory is converted based on the signal. Since the related signal is modulated by the modulator and the antenna is controlled to be transmitted from the antenna, it is applicable to a readable RFID system.

Further, according to the present invention, the transponder has a processing circuit including at least a demodulation section and a memory section, and when a signal is received by the antenna, the information is written in the memory section based on the signal. It is applicable to a writable RFID system.

[Brief description of drawings]

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

2 is a diagram showing a typical example of a wireless tag 13, and FIG.
(A) is a wireless tag 13a that mainly transmits and receives linearly polarized signals
2B is a plan view of the wireless tag 13b that mainly transmits and receives a circularly polarized signal, and FIG. 2C is a cross-sectional view of the wireless tag 13b taken along the section line I-I of the wireless tag 13b. It is a figure.

FIG. 3 is a diagram showing a configuration of an RFID system 2 which is a second embodiment of the present invention.

FIG. 4 is a diagram showing a configuration of an RFID system 3 according to a third embodiment of the present invention.

FIG. 5 is a diagram showing a configuration of an RFID system 4 according to a fourth embodiment of the present invention.

FIG. 6 is a front view of the radio wave reflection plate 21.

FIG. 7 is a perspective view of a radio wave reflection plate 23 which is a parabolic column surface.

FIG. 8 is a diagram showing a configuration of an RFID system 5 according to a fifth embodiment of the present invention.

FIG. 9 is a diagram showing a configuration of an RFID system 6 according to a sixth embodiment of the present invention.

FIG. 10 is a diagram showing a configuration of an RFID system 7 which is a seventh embodiment of the present invention.

FIG. 11 is a diagram showing a configuration of an RFID system 8 according to an eighth embodiment of the present invention.

FIG. 12 is a diagram showing a configuration of an RFID system 9 according to a ninth embodiment of the present invention.

FIG. 13 is a diagram showing a configuration of an RFID system 10 which is a tenth embodiment of the present invention.

FIG. 14 is a diagram showing a configuration of an RFID system 50 which is an eleventh embodiment of the present invention.

FIG. 15 is a perspective view of the RFID system 7.

16 is a diagram showing a basic configuration of the RFID system 15. FIG.

[Explanation of symbols]

1,2,3,4,5,6,7,8,9,10,50 R
FID system 11 Interrogator 12, 12a, 12b, 12c Interrogator antenna 13, 13a, 13b Radio tag 16 Carrier device 21, 21a, 21b, 22a, 22, 22b, 23,
24,25 Radio wave reflection plates 31, 31a, 31b Dipole antenna 32 Tag IC F focus

Claims (19)

[Claims] 1. An interrogator, an interrogator antenna connected to the interrogator for transmitting a signal, and a reflection including a part of a parabolic curve or a curve similar to the parabolic curve for reflecting the signal transmitted by the interrogator antenna. A radio wave reflector formed of a surface, and a transponder capable of receiving a signal from the interrogator antenna through at least the radio wave reflector and communicating with the interrogator. Wireless communication system. 2. The wireless communication system according to claim 1, wherein the interrogator antenna is arranged near a focal point of the reflecting surface. 3. The wireless communication system according to claim 1, wherein the transponder is arranged near a focal point of the reflecting surface. 4. A plurality of the interrogator antennas are arranged so as to face the reflection surface, and each interrogator antenna is set so as to point near a focal point of the reflection surface. The described wireless communication system. 5. A plurality of the interrogator antennas are arranged in the vicinity of the focal point of the reflecting surface, and the signals transmitted from the individual interrogator antennas are arranged at positions where the signals are reflected by the reflecting surface and travel in different directions. Claim 1 characterized by the above-mentioned.
The described wireless communication system. 6. The reflecting surface is a paraboloid of revolution or a paraboloid of revolution that includes the intersection of the parabolic curve or a curve similar thereto and the axis of the curve and the curve. The wireless communication system according to any one of 1 to 5. 7. The reflecting surface is a paraboloid of revolution or a paraboloid including a parabolic curve or a curve similar thereto and a portion of the curve deviating from the intersection of the axis of the curve. The wireless communication system according to any one of claims 1 to 5. 8. The wireless communication system according to claim 4, wherein a plurality of the interrogator antennas are connected to one interrogator. 9. The wireless communication system according to claim 4, wherein the plurality of interrogator antennas are connected to different interrogators, respectively. 10. Another radio wave reflection plate having a reflection surface facing the reflection surface is arranged, and the reflection surface of the other radio wave reflection plate places an incoming signal in the vicinity of the focal point of the reflection surface of the other radio wave reflection plate. The wireless communication system according to claim 1, wherein the wireless communication system reflects the reflected light in the direction of arrival. 11. The reflection surface of each of the two radio wave reflection plates is a paraboloid of revolution or a paraboloidal surface and is disposed so as to face each other with its axis aligned. Located near the focal point of the reflective surface of the plate, the transponder is
11. The wireless communication system according to claim 10, wherein the wireless communication system is arranged near the focal point of the reflecting surface of at least the other radio wave reflecting plate. 12. The reflection surfaces of the two radio wave reflection plates are paraboloids of revolution or paraboloids, and are arranged so as to face each other with their axes aligned, and two interrogator antennas are provided. 11. The wireless communication system according to claim 10, wherein the interrogator antenna is arranged near the respective focal points of the reflection surfaces of both radio wave reflection plates. 13. The wireless communication system according to claim 11, wherein the two radio wave reflection plates are arranged so that the focal points of the reflection surfaces are aligned with each other. 14. The reflection surface of the radio wave reflection plate is a paraboloid of revolution or a paraboloidal surface, and the reflection surface of the other radio wave reflection plate is a curved surface including a part of a circular curve or a curve similar thereto. And the radio wave reflection plate and the other radio wave reflection plate,
11. The wireless communication system according to claim 10, wherein the focal points of the reflecting surfaces are aligned with each other. 15. The reflection surface of the radio wave reflection plate is a paraboloid of revolution or a paraboloidal surface, and the reflection surface of the other radio wave reflection plate is planar and has an axis of the reflection surface of the radio wave reflection plate. The wireless communication system according to claim 10, wherein the wireless communication system is arranged orthogonally to. 16. A plurality of interrogator antennas are arranged,
The wireless communication system according to claim 10, wherein the signals transmitted by the interrogator antenna are circularly polarized signals having different turning directions. 17. A device for moving the transponder,
The wireless communication system according to claim 1, wherein communication is performed between the interrogator and the moving responder. 18. The transponder comprises at least a modulator,
A processing circuit having a memory unit for storing information and an antenna for transmitting and receiving a signal are provided, and when the processing circuit receives the signal at the antenna, the processing circuit relates to the information stored in the memory unit based on the signal. The wireless communication system according to claim 1, wherein the antenna is controlled so that the signal is modulated by the modulator and transmitted from the antenna. 19. The transponder comprises at least a demodulator,
A processing circuit having a memory unit for storing information and an antenna for receiving a signal, wherein the processing circuit writes information in the memory unit based on the signal when the antenna receives the signal. The wireless communication system according to claim 1.