JP2008164327A - Radio communication system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radio communication system, employing a passive method to use a small-sized and inexpensive module of simple structure, and having wide directivity to find the distance to a physical object regardless of presence of an ID. <P>SOLUTION: An electromagnetic coupling module 1 is mounted on the license plate 20 of an automobile 100, the coupling module 1 comprising: a radio IC chip therein storing information while being capable of transmission/reception processing on radio signals; and a feeder circuit board mounted with the IC chip and provided with a feeder circuit including a resonant circuit having a prescribed resonant frequency. Further, a reader 120 is mounted in the automobile 100. The reader 120 transmits a signal to the exterior to resonate the resonant circuit in the coupling module 1 by a reflected signal from the physical object while the module 1 transmits an electromagnetic wave via the license plate 20 to the exterior. Furthermore, the reader 120 detects the distance to the object based on an emitted signal from the module 1. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a wireless communication system, and more particularly to a wireless communication system that can be used for detecting a distance between a vehicle and an object using an RFID (Radio Frequency Identification) system.

  In recent years, an electronic license plate (smart plate) in which a wireless identification device storing a vehicle registration number, information described in an automobile registration file, and the like is attached to an automobile license plate has been studied and developed. In the smart plate, a radio signal is transmitted from a data terminal installed on a roadside or a gate of a traffic important point to another wireless device of the vehicle, and the vehicle information is obtained from a passing vehicle, thereby identifying the vehicle. This makes it possible to automatically collect highway tolls, parking fees, etc., making it easy to find stolen cars and to find violations of traffic laws.

  Conventionally, as described in Patent Document 1, a wireless identification device mounted on this type of vehicle is configured by modularizing a reception antenna, a transmission antenna, a signal amplification circuit, a control circuit, a memory, a modulation circuit, and the like. Therefore, an active method using a vehicle battery or a battery as a driving source has been studied.

  However, in such a wireless identification device, the number of parts of the module is large, it is structurally complicated, large, expensive, and the active system requires a connection circuit to the battery, and the battery is used. In such a case, there is a problem that the battery becomes unusable due to the life of the battery. Furthermore, since the antenna integrated with the module is used, it is necessary to reduce the size of the antenna as the module is downsized, and the small antenna has a problem that the directivity is narrowed.

  Patent Document 2 describes a radar system that measures the distance between vehicles. In this distance measurement system, a signal is transmitted from an in-vehicle device mounted on the host vehicle to an ID tag mounted on an object (another vehicle or a roadside marker), and this signal is received by the ID tag. Send the signal back to the in-vehicle device. The distance from the object is obtained from the time from transmission to response and the speed of the vehicle.

However, in such a measurement system, it is not possible to measure the distance inherently for an object on which an ID tag is not arranged, and it is necessary to place an ID tag on all objects other than the own vehicle. The problem was that the equipment cost would increase.
Utility Model Registration No. 2534890 JP 2005-31810 A

  SUMMARY OF THE INVENTION An object of the present invention is to provide a wireless communication system that employs a passive system, uses a small and inexpensive module with a simple configuration, has a wide directivity, and can detect the distance to an object regardless of the presence or absence of an ID tag. Is to provide.

In order to achieve the above object, a wireless communication system according to a first invention is:
An electromagnetic coupling module comprising: a wireless IC chip capable of storing information and capable of transmitting / receiving wireless signals; and a power supply circuit board including the wireless IC chip and provided with a power supply circuit including a resonance circuit having a predetermined resonance frequency When,
A vehicle license plate that is mounted with the electromagnetic coupling module and functions as a radiation plate by electromagnetic coupling with the electromagnetic coupling module;
An RFID reader mounted on a vehicle to which the license plate is attached,
The RFID reader transmits a signal to the outside,
The electromagnetic coupling module receives a reflected signal from the object of the signal through the license plate, and the resonant circuit resonates by the reflected signal and radiates electromagnetic waves to the outside through the license plate. ,
The RFID reader receives a radiation signal from the electromagnetic coupling module, and detects a distance to the object based on the radiation signal;
It is characterized by.

A wireless communication system according to a second invention is
A wireless IC chip capable of storing information and capable of transmitting and receiving wireless signals, and a power supply circuit board equipped with the wireless IC chip and provided with a power supply circuit including a resonance circuit having a predetermined resonance frequency, An electromagnetic coupling module attached to the vehicle body,
An RFID reader mounted on a vehicle to which the electromagnetic coupling module is attached,
The vehicle body part functions as a radiation plate by electromagnetic coupling with the electromagnetic coupling module,
The RFID reader transmits a signal to the outside,
The electromagnetic coupling module receives a reflected signal from an object of the signal through the vehicle body part, and the resonance circuit resonates by the reflected signal and radiates an electromagnetic wave to the outside through the vehicle body part. ,
The RFID reader receives a radiation signal from the electromagnetic coupling module, and detects a distance to the object based on the radiation signal;
It is characterized by.

  In the wireless communication system according to the first and second inventions, the wireless IC chip is mounted on the feeder circuit board and integrated with the license plate or the vehicle body part via the feeder circuit board, and the license plate or the vehicle body part is a signal. It functions as a radiation plate. The electromagnetic coupling module can be easily mounted on the license plate or any part of the car body part by bonding, and the license plate or car body part with a relatively large area functions as a radiation plate, so the directivity of the transmission / reception signal is widened. .

  Then, by mounting the RFID reader on the own vehicle, the electromagnetic coupling module operates by receiving the reflected signal reflected by the object from the RFID reader, and electromagnetic waves are transmitted through the license plate or the vehicle body part. To the outside. Based on this radiation signal, for example, the distance to the object is detected based on a change in gain characteristics and a response time. That is, the distance of the object (electromagnetic wave reflector) close to the host vehicle can be detected without providing a signal transmission / reception means such as an ID tag on the object, and an inexpensive wireless communication system can be constructed.

  Note that the wireless IC chip stores information such as a vehicle registration number and a car registration file, and is originally stored by receiving a signal from an RFID reader installed on the roadside or the like. It has a function to send back information. Therefore, the present invention is also used to detect the distance between a vehicle and an object existing around it by using an electronic license plate that has been studied and developed in recent years. Furthermore, in the present invention, a control system for driving support such as collision prevention and ensuring safety can be constructed based on the detection of distance.

  In addition, the electromagnetic coupling module has a simple and small configuration of a power supply circuit board provided with a wireless IC chip and a power supply circuit. Further, the electromagnetic coupling module resonates with a signal from an RFID reader and uses this signal (electromagnetic wave) as a drive source. It is passive and does not require batteries or batteries. Therefore, a connection circuit to the battery is unnecessary, and there is no possibility that the battery cannot be used due to the life of the battery.

  Since the frequency of the transmission signal radiated from the license plate or the body part and the frequency of the reception signal supplied to the wireless IC chip are substantially determined by the resonance frequency of the resonance circuit in the power supply circuit board, various shapes and sizes are available. Regardless of whether it is mounted on a license plate or mounted at any position on the vehicle body, the frequency characteristic does not change and a stable frequency characteristic can be obtained.

  In the wireless communication system according to the present invention, the license plate or the vehicle body part to which the electromagnetic coupling module is attached may be made of metal or dielectric (for example, resin). Here, the dielectric means one having a dielectric constant of 1 or more. By combining the characteristic impedance of the input / output unit of the electromagnetic coupling module and the characteristic impedance of the dielectric interface, an electromagnetic wave is input into the dielectric, and the dielectric functions as an electromagnetic radiator.

  Further, the resonance circuit provided on the power supply circuit board may include an inductor, and may further be configured as a lumped constant type resonance circuit by a capacitor and an inductor. The lumped constant type resonance circuit may be an LC series resonance circuit or an LC parallel resonance circuit, or may include a plurality of LC series resonance circuits or a plurality of LC parallel resonance circuits. The resonant circuit can also be composed of a distributed constant type resonant circuit, in which case the inductor of the resonant circuit is formed by a stripline or the like.

  According to the present invention, a small-sized and inexpensive electromagnetic coupling module with a simple configuration is attached to the license plate or the vehicle body part, and the RFID reader is mounted on the vehicle. In addition, wireless communication with wide directivity is possible, and a wireless communication system that detects the distance to an obstacle close to the vehicle can be configured at low cost.

  Embodiments of a wireless communication system according to the present invention will be described below with reference to the accompanying drawings.

(Number plate configuration, see Figs. 1-3)
A first example of a license plate used in a wireless communication system according to the present invention is shown in FIG. The number plate 20 is made of a dielectric material such as metal or resin, and the electromagnetic coupling module 1 is bonded to the back surface thereof. The electromagnetic coupling module 1 is a power supply provided with a wireless IC chip 5 capable of storing information and capable of transmitting and receiving wireless signals, and a power supply circuit including the wireless IC chip 5 and a resonance circuit having a predetermined resonance frequency. The circuit board 10 is comprised. The information stored in the wireless IC chip 5 is, for example, vehicle inspection information described in a vehicle registration number or an automobile registration file.

  FIG. 2 shows a second example of the license plate 20 in which the electromagnetic coupling module 1 is sealed with a cover 21. FIG. 3 shows a third example of the license plate 20 in which the electromagnetic coupling module 1 is built. Specifically, a recess 22 is formed in a part of the license plate 20, and the electromagnetic coupling module 1 is accommodated in the recess 22 and sealed with a tape 23.

  The surface on which the electromagnetic coupling module 1 is mounted may be either the back surface or the front surface of the license plate 20. Since the electromagnetic coupling module 1 has a thickness of about 2 to 3 mm, it can be sufficiently attached to an existing recess. When mounted on the back surface of the plate 20, the electromagnetic coupling module 1 does not exist on the surface that is the signal radiation surface, so that stable signal radiation characteristics can be obtained. Moreover, if the electromagnetic coupling module 1 is sealed, the environmental resistance is improved.

  When the cover 21 is used as in the second example, a light emitting element may be provided on the cover 21, a communication test with the electromagnetic coupling module 1 may be performed in advance with a handy reader, and the light emitting element may be turned on if normal. . The malfunction of the electromagnetic coupling module can be confirmed visually.

  1 to 3 schematically show the license plate 20 and the electromagnetic coupling module 1, and the sizes of the two do not correspond to each other at an accurate scale ratio. Incidentally, the size of the electromagnetic coupling module 1 is about several centimeters in length and width, and the thickness is about 3 mm at the maximum.

(Mounting on the body, see Fig. 4)
The electromagnetic coupling module 1 may be bonded to the vehicle body portion 101 of the automobile 100 as shown in FIG. The vehicle body portion 101 may be made of metal or made of a dielectric (made of resin).

  The automobile 100 is equipped with an RFID reader 120 that activates the electromagnetic coupling module 1 and transmits and receives signals. Even when the electromagnetic coupling module 1 is attached to the license plate 20, the RFID reader 120 is mounted on the automobile 100 (see FIGS. 8 to 11).

(Specific examples of electromagnetic coupling modules, see FIGS. 5 to 7)
An electromagnetic coupling module 1 as a specific example shown in FIGS. 5 and 6 includes a wireless IC chip 5 and a power supply circuit board 10 having the wireless IC chip 5 mounted on the upper surface thereof. Is attached with an insulating adhesive 18. The wireless IC chip 5 includes a clock circuit, a logic circuit, and a memory circuit, stores necessary information, and is directly electrically connected to the power supply circuit 16 built in the power supply circuit board 10.

  The power feeding circuit 16 is a circuit for supplying a transmission signal having a predetermined frequency to the license plate 20 or the vehicle body part 101 and / or a reception signal having a predetermined frequency from a signal received by the license plate 20 or the vehicle body part 101. And a resonance circuit that resonates at the frequency of the transmission / reception signal.

  The power supply circuit board 10 incorporates a power supply circuit 16 configured by a lumped constant LC series resonance circuit including a helical inductance element L and capacitance elements C1 and C2. Specifically, as shown in FIG. 7, the feeder circuit board 10 is a laminate of ceramic sheets 11 </ b> A to 11 </ b> G made of a dielectric material, press-bonded, and fired. A sheet 11 </ b> A having a connection electrode 12 and a via-hole conductor 13 a, a capacitor electrode A sheet 11B formed with a capacitor electrode 14b and a via hole conductor 13b, a sheet 11D formed with a via hole conductor 13c, a sheet 11E formed with a conductor pattern 15a and a via hole conductor 13d, and a sheet 11F formed with a via hole conductor 13e. It consists of a sheet 11G on which a conductor pattern 15b is formed (one or a plurality of sheets). Each of the ceramic sheets 11A to 11G may be a sheet made of a magnetic ceramic material, and the feeder circuit board 10 may be manufactured by a multilayer board manufacturing process such as a conventionally used sheet lamination method or thick film printing method. Can be easily obtained.

  By laminating the above sheets 11A to 11G, the inductance element L whose helical winding axis is parallel to the license plate 20, the capacitor electrode 14b is connected to both ends of the inductance element L, and the capacitor electrode 14a is a via hole. Capacitance elements C1 and C2 connected to the connection electrode 12 through the conductor 13a are formed. Then, the connection electrode 12 which is a substrate side electrode pattern is electrically connected to a chip side electrode pattern (not shown) of the wireless IC chip 5 via the solder bump 6.

  That is, among the elements constituting the power feeding circuit, the transmission signal is fed from the inductance element L, which is a coiled electrode pattern, to the license plate 20 via a magnetic field, and the reception signal from the license plate 20 Power is supplied to the inductance element L. Therefore, it is desirable that the feeder circuit board 10 be laid out so that the inductance element is close to the license plate 20 among the inductance elements and capacitance elements constituting the resonance circuit.

  FIG. 6 shows an equivalent circuit of the electromagnetic coupling module 1. The electromagnetic coupling module 1 includes a high-frequency signal (for example, a radio frequency signal radiated from an RFID reader 120 (see FIGS. 8 to 11) mounted on the automobile 100 or a reader (not shown) installed on a roadside or a highway gate. , UHF frequency band) is received by the license plate 20 or the vehicle body portion 101, and is electrically connected to the plate 20 or the vehicle body portion 101. The power feeding circuit 16 (LC series resonance including the inductance element L and the capacitance elements C1 and C2) Circuit) and only the received signal in a predetermined frequency band is supplied to the wireless IC chip 5. On the other hand, after taking out predetermined energy from this received signal, applying information reflected in the radio IC chip 5 with this energy as a driving source, and applying reflection modulation to the input signal, and matching it to a predetermined frequency by the power feeding circuit 16, A transmission signal is transmitted from the inductance element L of the power feeding circuit 16 to the license plate 20 or the vehicle body portion 101 via magnetic field coupling, and transmitted from the license plate 20 to the reader. In addition, the electromagnetic coupling module 1 and the reader 120 are used to detect the distance to an obstacle or another vehicle that is close to the automobile 100, which will be described later.

  The coupling between the power feeding circuit 16 and the license plate 20 or the vehicle body portion 101 is mainly coupling via a magnetic field, but coupling via an electric field may exist. In the present invention, “electromagnetic field coupling” means coupling via an electric field and / or a magnetic field.

  In the electromagnetic coupling module 1, the wireless IC chip 5 is electrically directly connected to the power supply circuit board 10 including the power supply circuit 16, and the power supply circuit board 10 has substantially the same area as the wireless IC chip 5, and Since it is rigid, the wireless IC chip 5 can be positioned and mounted with extremely high accuracy. In addition, since the power supply circuit board 10 is made of a ceramic material and has heat resistance, the wireless IC chip 5 can be soldered to the power supply circuit board 10.

  In the power feeding circuit 16, the resonance frequency characteristic is determined by a resonance circuit composed of the inductance element L and the capacitance elements C 1 and C 2. The resonance frequency of the signal radiated from the license plate 20 or the vehicle body portion 101 substantially corresponds to the self-resonance frequency of the power feeding circuit 16, and the maximum gain of the signal is the size and shape of the power feeding circuit 16, the number of the power feeding circuit 16 and the number. It is substantially determined by at least one of the distance from the plate 20 or the vehicle body portion 101 and the medium.

  Further, since the capacitance elements C1 and C2 are inserted in the subsequent stage of the wireless IC chip 5, a low frequency surge can be cut by the elements C1 and C2, and the wireless IC chip 5 can be protected from the surge.

  The resonance circuit may also serve as a matching circuit for matching the impedance of the wireless IC chip 5 with the impedance of the license plate 20 or the vehicle body portion 101. Alternatively, the power feeding circuit board 10 may further include a matching circuit that is configured by an inductance element and a capacitance element and is provided separately from the resonance circuit. If an attempt is made to add a function of a matching circuit to the resonance circuit, the design of the resonance circuit tends to be complicated. If a matching circuit is provided separately from the resonance circuit, the resonance circuit and the matching circuit can be designed independently.

(See distance detection example 1, FIG. 8)
Next, a distance detection example 1 by a wireless communication system using the electromagnetic coupling module 1 and the RFID reader 120 described above will be described.

  As shown in FIG. 8, when the automobile 100 to which the license plate 20 is attached is traveling on the road 150 in the direction of arrow A, a signal having a predetermined frequency is transmitted from the RFID reader 120 mounted on the automobile 100. Sent to the outside. When the signal hits the guard rail 151 installed on the road side, the signal is reflected. The electromagnetic coupling module 1 receives the reflected signal through the license plate 20. The resonance circuit 16 resonates due to the received signal, and the electromagnetic coupling module 1 radiates electromagnetic waves to the outside via the license plate 20. In addition, the radiation characteristic of electromagnetic waves when passing through the license plate 20 of the electromagnetic coupling module 1 is a region B indicated by a one-dot chain line.

  The RFID reader 120 receives the electromagnetic wave. At this time, the reflected signal level input to the electromagnetic coupling module 1 via the license plate 20 varies depending on the distance to the guard rail 151. That is, the closer the distance to the guard rail 151 is, the larger the reflected signal level is, and the farther the distance is, the smaller the reflected signal level is. In the RFID reader 120, the relationship between the distance to an object such as a guardrail and the reflected signal level received by the electromagnetic coupling module 1 is stored in a memory provided therein, and the distance is determined according to the received reflected signal level. Is detected.

  When the detected distance falls below a predetermined allowable value, the driver is warned by voice or flashing lamps, driving assistance control (for example, automatic braking, pretension on the seat belt) Give).

  Further, the gain characteristics and response time of the electromagnetic coupling module 1 change according to the distance from the automobile 110 traveling in front of the automobile 100. Therefore, it is also possible to detect the distance to other vehicles existing in the communication area B. In addition, if an electromagnetic coupling module is mounted on the license plate installed at the rear of the vehicle, it is possible to detect the distance from the following vehicle.

  The electromagnetic coupling module 1 reacts to a high-frequency signal radiated from an RFID reader disposed in a roadside band or the like, and uses information stored in the wireless IC chip 5 (vehicle information such as a registration number) as a license plate. Radiated from 20, and transmitted to a roadside band RFID reader. That is, the license plate 20 also functions as an electronic license plate (smart plate).

  In this wireless communication system, the electromagnetic coupling module 1 has a simple and small configuration of a wireless IC chip 5 and a power supply circuit board 10, and resonates with a signal (electromagnetic wave) from an RFID reader. And does not require batteries or batteries. Therefore, a connection circuit to the battery is unnecessary, and there is no possibility that the battery cannot be used due to the life of the battery. In addition, since the license plate 20 having a relatively large area functions as a radiation plate, the directivity of transmission / reception signals is widened.

  The object whose distance is to be detected may be any object that reflects electromagnetic waves, and it is not necessary to attach an ID tag or the like to the object as in the prior art, and a wireless communication system can be constructed at low cost.

(See distance detection example 2, FIG. 9)
Next, a distance detection example 2 by a wireless communication system using the electromagnetic coupling module 1 and the RFID reader 120 will be described.

  As shown in FIG. 9, the electromagnetic coupling module 1 is mounted on the side surface of the vehicle body portion 101 of the automobile 100, and when the automobiles 100 and 110 are running in parallel on a road 150, A signal having a predetermined frequency is transmitted from the reader 120 to the outside of the automobile 100. When the signal hits the automobile 110, the signal is reflected. The electromagnetic coupling module 1 receives the reflected signal via the vehicle body portion 101. The resonance circuit 16 resonates by the received signal, and the electromagnetic coupling module 1 radiates electromagnetic waves to the outside via the vehicle body portion 101. The radiation characteristic of the electromagnetic wave when passing through the vehicle body portion 101 of the electromagnetic coupling module 1 is a region B indicated by a one-dot chain line.

  The RFID reader 120 receives the electromagnetic wave. At this time, the reflected signal level input to the electromagnetic coupling module 1 via the vehicle body portion 101 varies depending on the distance to the automobile 110. That is, the closer the distance to the automobile 110 is, the larger the reflected signal level is, and the farther the distance is, the smaller the reflected signal level is. In the RFID reader 120, the relationship between the distance to an object such as a car running in parallel and the reflected signal level received by the electromagnetic coupling module 1 is stored in a memory provided therein, and the received reflected signal level is stored in the memory. The distance is detected accordingly. As described in the distance detection example 1, the warning or the driving support control is performed when the detected distance is less than the allowable value.

(Communication example 1 with other vehicle, see FIG. 10)
Next, communication example 1 with another vehicle using the electromagnetic coupling module 1 and the RFID reader 120 will be described.

  As shown in FIG. 10, the electromagnetic coupling module 1 is mounted on the side surfaces of the vehicle body portions 101 and 111 in the automobiles 100 and 110, and the RFID reader 120 is also mounted. In the automobile 100, the radiation directivity of the electromagnetic coupling module 1 using the vehicle body portion 101 as a radiator is a communication area B indicated by a one-dot chain line. When the electromagnetic coupling module 1 of another automobile 110 that travels laterally enters this communication area B, the electromagnetic coupling module 1 is activated by a signal from the reader 120 of the automobile 110 and is stored in the wireless IC chip 5. Is transmitted to the RFID reader 120 of the automobile 100. The electromagnetic coupling module 1 of the automobile 100 is also activated by a signal from the reader 120 of the own vehicle or a signal from the reader 120 of the automobile 110 that is another vehicle, and is stored in the wireless IC chip 5. Information is transmitted to the reader 120 of the automobile 110. In this way, the parallel running automobiles 100 and 110 can acquire information on each other's vehicles.

(Refer to communication example 2 with other vehicle, Fig. 11)
As shown in FIG. 11, a license plate 20 having the electromagnetic coupling module 1 mounted thereon is attached to the automobile 100, and a license plate 20 having the electromagnetic coupling module 1 mounted thereon is attached to the other automobile 110. In the automobile 100, the radiation directivity of the electromagnetic coupling module 1 using the license plate 20 as a radiation plate is a communication area B indicated by a one-dot chain line. When the electromagnetic coupling module 1 of another automobile 110 traveling in the front enters the communication area B, the module 1 is activated and information stored in the wireless IC chip 5 is RFIDd via the module 1 of the automobile 100. Is transmitted to the reader 120. The electromagnetic coupling module 1 of the automobile 100 is also activated by a signal from the reader 120 of the own vehicle or a signal from the reader 120 of the automobile 110 that is another vehicle, and is stored in the wireless IC chip 5. Information is transmitted to the reader 120 of the automobile 110. In this manner, the automobiles 100 and 110 located in the front and rear can acquire information on each other's vehicles.

(Other examples)
In addition, the radio | wireless communications system which concerns on this invention is not limited to the said Example, It can change variously within the range of the summary.

  In particular, the details of the resonance circuit, which is the internal configuration of the feeder circuit board, are arbitrary. Furthermore, processing other than solder bumps may be used to connect the wireless IC chip on the power supply circuit board.

It is a perspective view which shows the 1st example of a license plate provided with the electromagnetic coupling module. It is a perspective view which shows the 2nd example of a license plate provided with the electromagnetic coupling module. It is sectional drawing which shows the 3rd example of a license plate provided with the electromagnetic coupling module. It is a perspective view which shows the motor vehicle provided with the electromagnetic coupling module. It is sectional drawing which shows the specific example of an electromagnetic coupling module. It is an equivalent circuit diagram of the electromagnetic coupling module. It is a disassembled perspective view which shows the electric power feeding circuit board of the said electromagnetic coupling module. It is explanatory drawing which shows the 1st example of the distance detection by the radio | wireless communications system which concerns on this invention. It is explanatory drawing which shows the 2nd example of the distance detection by the radio | wireless communications system which concerns on this invention. It is explanatory drawing which shows the example 1 of communication with the other vehicle by the radio | wireless communications system which concerns on this invention. It is explanatory drawing which shows the example 2 of communication with the other vehicle by the radio | wireless communications system which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Electromagnetic coupling module 5 ... Wireless IC chip 10 ... Feeding circuit board 16 ... Feeding circuit 20 ... License plate 100,110 ... Automobile 101 ... Car body part 120 ... RFID reader L ... Inductance element C1, C2 ... Capacitance element

Claims (5)

An electromagnetic coupling module comprising: a wireless IC chip capable of storing information and capable of transmitting / receiving wireless signals; and a power supply circuit board including the wireless IC chip and provided with a power supply circuit including a resonance circuit having a predetermined resonance frequency When,
A vehicle license plate that is mounted with the electromagnetic coupling module and functions as a radiation plate by electromagnetic coupling with the electromagnetic coupling module;
An RFID reader mounted on a vehicle to which the license plate is attached,
The RFID reader transmits a signal to the outside,
The electromagnetic coupling module receives a reflected signal from the object of the signal through the license plate, and the resonant circuit resonates by the reflected signal and radiates electromagnetic waves to the outside through the license plate. ,
The RFID reader receives a radiation signal from the electromagnetic coupling module, and detects a distance to the object based on the radiation signal;
A wireless communication system. A wireless IC chip capable of storing information and capable of transmitting and receiving wireless signals, and a power supply circuit board equipped with the wireless IC chip and provided with a power supply circuit including a resonance circuit having a predetermined resonance frequency, An electromagnetic coupling module attached to the vehicle body,
An RFID reader mounted on a vehicle to which the electromagnetic coupling module is attached,
The vehicle body part functions as a radiation plate by electromagnetic coupling with the electromagnetic coupling module,
The RFID reader transmits a signal to the outside,
The electromagnetic coupling module receives a reflected signal from an object of the signal through the vehicle body part, and the resonance circuit resonates by the reflected signal and radiates an electromagnetic wave to the outside through the vehicle body part. ,
The RFID reader receives a radiation signal from the electromagnetic coupling module, and detects a distance to the object based on the radiation signal;
A wireless communication system.   3. The wireless communication according to claim 1, wherein the RFID reader includes storage means for storing a relationship between a radiation signal characteristic from the electromagnetic coupling module and a distance to an object. system.   The wireless communication system according to claim 1 or 2, wherein the electromagnetic coupling module is attached to a license plate or a vehicle body part of another vehicle.   The wireless communication system according to claim 1, wherein the resonance circuit includes an inductor.

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