JP2003087139A - Circuit for automatically adjusting sensitivity of on- vehicle machine in etc system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide such an on-vehicle automatic sensitivity adjusting circuit in an ETC (electronic toll collection) system, which can correspond to a plurality of applications. SOLUTION: This on-vehicle automatic sensitivity adjusting circuit consists of a means for deciding an optimum application at a position at which a vehicle currently travels, reference voltage generating means for storing a plurality of reference voltage defined in each application and generating a reference voltage fitting the application decided by the optimum application deciding means, and a means for comparing the reference voltage with a received signal obtained by applying and shaping the received radio wave in the each application and switching the on-vehicle machine to be communication when the received signal voltage is higher than the reference.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-stop toll road toll collection system (Electro) using wireless communication.
nic Toll Collection: ETC
(Referred to as a system) for the automatic sensitivity adjustment circuit of the vehicle-mounted device.

[0002]

2. Description of the Related Art As shown in FIG. 4, an ETC system has a charging antenna 43 corresponding to each lane on gantry 41, 42 provided across a road 40 having a plurality of lanes. , 44 are provided, necessary information is wirelessly communicated with an in-vehicle device 46 mounted on a vehicle 45 passing thereunder, and a toll charge process is automatically performed. Therefore, the vehicle 45 can pass through without stopping at a tollgate, and it is possible to bring about a great effect in eliminating traffic congestion on the toll road.

The vehicle-mounted device 46 in this ETC system, as shown in FIG.
The signal from the antenna 51, which exchanges signals with 3, 44, is input to the comparator 54 through the detection circuit 52 and the low-pass filter (LPF) 53, and compared with the reference voltage created by the variable resistor 55, for this charging. Antennas 43, 4
The vehicle-mounted device 46 (not shown in FIG. 5) is configured to communicate only when the signal from 4 is higher than the reference voltage.

[0004]

However, the vehicle-mounted device 46 in such an ETC system is
6 is not used only for the communication of ETC data, but it is possible to receive a broadcast radio wave such as a character radio as disclosed in Japanese Patent Laid-Open No. 11-339181, for example.
Communication of ETC data is performed where data is transmitted / received, and character radio or the like is received where transmission / reception of ETC data is not required, so that the communication area is changed so as to support multiple applications. There is.

However, the conventional in-vehicle device 4 for the ETC system 4
As for the sensitivity in No. 6, since the reference voltage is determined by the variable resistor 55 as shown in FIG. 5, the size of the communication area can only be changed by the pattern of the charging antennas 43 and 44 and the transmission output. It was Therefore, it is necessary to adjust the value of the variable resistor 55 in order to deal with a plurality of applications as described above, but adjustment during operation is substantially impossible.

Therefore, it is an object of the present invention to provide a sensitivity automatic adjustment circuit for an in-vehicle device in an ETC system which can support a plurality of applications.

[0007]

In order to solve the above problems, according to the present invention, as described in claim 1, ETC
An ETC system sensitivity automatic adjustment circuit for an in-vehicle device capable of receiving a plurality of applications such as system-related radio waves, road condition broadcast radio waves, general radio and FM broadcast radio waves. An optimal application determining means for determining an optimal application at a traveling position, and an application determined by the optimal application determining means for storing a plurality of reference voltages defined for each application,
Alternatively, a reference voltage generating means for generating a reference voltage suitable for an application designated separately is compared with the reference voltage generated by the reference voltage generating means and the reception signal obtained by amplifying and shaping the reception radio wave for each application, and the reception signal is When the voltage is higher than the reference voltage, the in-vehicle device is switched to the communicable mode, and the in-vehicle device is switched to the communicable mode by comparing the received signal with the reference voltage generated corresponding to the optimum application in the traveling position. It is characterized by enabling communication with an optimum application by means.

By configuring the in-vehicle device sensitivity automatic adjustment circuit in the ETC system as described above, the reference voltage corresponding to the optimum application at the traveling position can be automatically generated, thereby communicating with the application at the traveling position. It will be possible.

The determination of the optimum application at the traveling position is characterized in that the optimum application determining means obtains the application information at the traveling position from a notice antenna provided on the road. To do. The optimum application determining means is characterized in that the application information at the traveling position is obtained by a sensor attached to the bottom surface of the vehicle for receiving information from the loop coil having the road surface embedded therein. The optimum application determination means is configured to store application position information stored in advance and GPS (Global).
It is characterized in that the optimum application is judged by comparing the current position information acquired by the Positioning System) system.

By doing so, for example, in the case of claim 2, application information can be obtained without using a special antenna by using the antenna for the vehicle-mounted device in the ETC system, and in the case of claim 3. Is, because the distance between the loop antenna embedded in the road surface and the sensor installed in the vehicle does not differ extremely depending on the vehicle,
It is possible to send and receive stable information. In the case of claim 4, the car navigation system or the like can be used as it is, and the application information can be surely obtained at any place.

Further, the reference voltage generating means comprises a new CPU by configuring the reference voltage generating means by using an existing CPU in the vehicle-mounted device.
It can be constructed inexpensively without using.

According to the sixth aspect of the automatic sensitivity adjustment circuit of the vehicle-mounted device, the means for switching the vehicle-mounted device to the communicable state, when switching the vehicle-mounted device to the communicable state,
The feature is that the transmission output to the application is also switched at the same time.

By doing so, it becomes possible to reliably send and receive data to and from the ETC system and to and from each application.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be exemplarily described in detail below with reference to the drawings. However, the dimensions, materials, shapes, relative positions, and the like of the constituent parts described in this embodiment are not intended to limit the scope of the present invention thereto, unless otherwise specified, and are merely It is only an example.

FIG. 1 is a schematic block diagram of an apparatus showing an embodiment of the present invention, and FIG. 2 schematically shows a receivable area in each application such as communication with an ETC system and reception of road condition broadcasting. 3 and 4 are diagrams showing a loop coil embedded in a road surface for transmitting application information. In the figure, 1 is an antenna, 2 is a detection circuit, 3 is a low-pass filter (LPF), 4 is a comparator, 5
Is a digital / analog converter (D / A-C), 6 stores a reference voltage corresponding to a plurality of applications, and the reference voltage corresponding to the application selected by the optimum application selecting device 7 is stored in the digital / analog converter (D).
/ A-C) 5 is an arithmetic unit (CPU), 7 is an optimum application selecting device for selecting an optimum application for the current running position, and 8 is a current position judging device for judging the current position, which is shown in FIG. Application notice signal issued from a gantry for a notice antenna provided in the same shape as the gantry 41, 42 across the road 40 as shown in FIG. 3, an application from the loop antenna 30 embedded in the road surface shown in FIG. A device that receives a warning signal or a GPS (Global Position)
This is a device that determines the current traveling position based on the current position information and the like obtained by the Ning System) system or the like.
Reference numeral 9 is an application selection device for manually selecting a desired application from a plurality of applications.

In FIG. 2, 20 is, for example, 43 in FIG.
ETC system antennas on the gantry 41 and 42 shown by 44, 21 is a communication area for the ETC system created on the road by this antenna 20, 22 is a communication area for applications such as road information, and 23 is The direction of travel of the car. In FIG. 3, reference numeral 30 denotes a loop antenna embedded in the road 40 in order to give advance notice that an application such as road information will start.

Now, for example, the in-vehicle device 46 of the ETC system
1 is configured so as to be able to receive or communicate with a plurality of applications such as general radio, FM broadcasting, road condition broadcasting, and ETC related communication, first, FIG.
The current position determining device 8 determines the current traveling position of the vehicle and informs the optimum application selecting device 7 of it. The determination of the current position of this vehicle is made by, for example, road condition broadcasting, ETC.
Regarding the related communication, the road 40 as shown in FIG.
The application notice signal issued from the notice antenna gantry provided in the same manner as the gantry 41, 42 across the line, the application notice signal from the loop antenna 30 embedded in the road surface shown in FIG. 3, and the like are used. For general radio and FM broadcasting, a car navigation system or a GPS system is used.

Of these, the application notice signal emitted from the notice antenna gantry or the like is a normal E signal.
It suffices if it is received by the communication antenna of the in-vehicle device for TC system, and the loop antenna 3 embedded in the road surface shown in FIG.
In the case of the application warning signal from 0, a sensor is attached to the bottom surface of the vehicle, and the warning signal is obtained by the sensor. For general radio and FM broadcasting, an antenna used for car navigation or GPS system is used.

The notice signal relating to each application or the vehicle position signal thus received is sent to the optimum application selecting device 7. The optimum application selecting device 7 determines the position where communication or road condition broadcasting is performed in the ETC system when the current position determining device 8 is configured by a car navigation system or a GPS system, or in the case of general radio or FM broadcasting. Stores the transmission frequency of the broadcasting station in the area.
Then, based on the signals from the notice antenna and the GPS system, the optimum application in the area is selected.

That is, when the ETC system becomes close to the ETC system, the priority is given to the corresponding ETC system. When the ETC system is separated from the ETC system, the road information is displayed in the area where the road information is passed. In a place where there is neither road information nor an ETC system, a general radio or FM broadcasting station in the area is selected.

The arithmetic unit (CPU) 6 has the above-mentioned E
TC related communication, reception of road condition broadcasting, general radio and F
The reference voltage corresponding to each reception of the M broadcast and the like is stored, and when the signal of the optimum application is sent from the optimum application selecting device 7, the reference voltage corresponding to the application is changed to the digital / analog converter 5 Is configured to be sent to.

In the sensitivity automatic adjusting circuit of the vehicle-mounted device in the ETC system of the present invention thus constructed, the device for judging the current position is, for example, the road 40 as shown in FIG.
In the case of the application notice signal transmitted from the notice antenna gantry or the like provided in the same shape as the gantry 41, 42 straddling over the arrow, as shown in FIG.
When the vehicle advances in the direction of 3, the current position determination device 8 first detects a warning signal for road condition broadcasting, the signal is transmitted to the optimum application selecting device 7, and the optimum application selecting device 7 causes the road condition broadcasting to be performed. Is started, and it is transmitted to the arithmetic unit (CPU) 6. Therefore, the arithmetic unit (CPU) 6 sends a reference voltage suitable for road condition broadcasting to the analog / digital converter (D / A-C) 5, and the analog / digital converter (D / A-C) 5 corresponds to the signal. The generated reference voltage is generated and sent to the comparator 4. Therefore, when the vehicle enters the area indicated by 22 in FIG. 2, the comparator 4 receives the signal of the road condition broadcast received by the antenna 1, detected by the detection circuit 2 and transmitted through the low pass filter (LPF) 3. And the reference signal is compared with each other, and if the signal of the road condition broadcast is larger than the comparison signal, the in-vehicle device (not shown) of the ETC system is switched to receive the road condition broadcast.

When the vehicle further advances in this state and the ETC system advance notice signal is received by the current position determination device 8, this signal is transmitted from the current position determination device 8 to the optimum application selection device 7. The optimum application selection device 7 notifies the arithmetic unit (CPU) 6 that the ETC system is approaching. Therefore, the arithmetic unit (CPU) 6 supplies a reference voltage suitable for the communication of the ETC system signal to the analog / digital converter (D / A-).
C) Send to 5, analog / digital converter (D / A
-C) 5 generates a reference voltage corresponding to the signal and sends it to the comparator 4. Therefore, the car is moving and the area 2 in FIG.
When it enters 1, the comparator 4 compares the reference signal with the ETC system signal received by the antenna 1, detected by the detection circuit 2 and sent through the low pass filter (LPF) 3, and the signal of the ETC system is compared. Is larger than the comparison signal, the in-vehicle unit (not shown) of the ETC system is switched to the ETC system communication.

Therefore, the ETC system vehicle-mounted device (not shown) wirelessly communicates necessary information with the ETC system, and the toll fee is automatically charged. Therefore, the vehicle 45 can pass without stopping at a tollgate or the like.

The ETC shown in the area 21 in FIG.
After passing through the system area, the radio wave from the ETC system disappears and the output of the comparator 4 disappears. If the road condition broadcasting as described above continues, the in-vehicle unit of the ETC system receives the road condition broadcasting. It is switched and the road condition broadcast is received.

The above is the case where the application notice signal is emitted from the notice antenna gantry provided in the same manner as the gantry 41, 42. This is from the loop antenna 30 embedded in the road surface shown in FIG. The same applies to the case of the application notification signal, and the same operation can be performed by receiving the application notification signal from the loop antenna 30 by the sensor mounted on the bottom surface of the vehicle.

When the current position of the vehicle is given by the car navigation system or GPS system, the current position signal from the car navigation system, GPS system or the like is sent to the optimum application selecting device 7, and the optimum application selecting device 7 is sent. Remembers E
The optimum application is selected from the position of the TC system, the position where the road condition is broadcast, etc., and it is sent to the arithmetic unit (CPU) 6. Therefore, arithmetic unit (CPU)
Reference numeral 6 denotes an analog / digital converter (D / A) which is a reference voltage suitable for the application selected as described above.
-C) 5 and send to analog / digital converter (D /
A-C) 5 generates a reference voltage corresponding to the signal and sends it to the comparator 4. Therefore, the comparator 4 receives the signal at the antenna 1 and detects it at the detection circuit 2 to obtain a low-pass filter (LP
F) The signal of the application sent through 3 is compared with this reference signal, and if the signal of the application is larger than the comparison signal, the in-vehicle unit (not shown) of the ETC system is switched to receive the selected application.

This is exactly the same also in the case of reception of a general radio or FM broadcast, and in the case of reception of such a general radio or FM broadcast, the frequency of the broadcasting station in the area is selected and Since the reference voltage optimum for receiving the frequency is output by the arithmetic unit (CPU) 6, the broadcast can be received by the optimum method. When a general radio broadcast or FM broadcast and a road condition broadcast can be received at the same time, an arbitrary application can be selected by an input from the application selection device 9.

The automatic sensitivity adjustment circuit of the vehicle-mounted device in the ETC system of the present invention is used for communication with such ETC system, reception of road condition broadcast, general radio broadcast and F
It is possible to use not only the reception of the M broadcast but also the transmission of the signal in the communication with other vehicles, for example, in order to make the transmission output suitable for the optimum application selected by the optimum application selection device 7. . In this case, the output of the comparator 4 may be input not only to the receiving system but also to a circuit for operating the system for signal transmission, thereby changing the transmission output.

[0030]

As described above, according to the present invention as set forth in claim 1, the reference voltage corresponding to the optimum application at the traveling position can be automatically generated, thereby enabling communication with the application at the traveling position. become.

According to the present invention described in claims 2 to 4, for example, in the case of claim 2, application information can be obtained without using a special antenna by using an antenna for a vehicle-mounted device in the ETC system. According to the third aspect of the invention, the distance between the loop antenna embedded in the road surface and the sensor provided in the vehicle does not vary greatly depending on the vehicle, so that stable information transmission / reception is possible.
In the case of claim 4, the car navigation system or the like can be used as it is, and the application information can be surely obtained at any place.

According to the fifth aspect of the present invention, the reference voltage generating means is configured by using the existing CPU in the vehicle-mounted device, so that the cost can be reduced without using a new CPU.

According to the present invention described in claim 6, it becomes possible to surely perform transmission / reception of data with the ETC system and transmission / reception of data with each application.

[Brief description of drawings]

FIG. 1 is a schematic block diagram of an apparatus showing an embodiment of the present invention.

FIG. 2 is a diagram schematically showing a receivable area in each application such as communication with an ETC system and reception of a road condition broadcast.

FIG. 3 is a diagram showing a loop coil embedded in a road surface for transmitting application information.

FIG. 4 is a diagram for explaining an outline of a non-stop toll road toll collection system (ETC system) using wireless.

FIG. 5 is a block diagram of a sensitivity adjustment circuit of a vehicle-mounted device in a conventional ETC system.

[Explanation of symbols]

1 antenna 2 Detection circuit 3 Low pass filter (LPF) 4 comparator 5 Digital / Analog converter (D / A-C) 6 arithmetic unit (CPU) 7 Optimal application selection device 8 Current position determination device 9 Application selection device

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Claims (6)

[Claims] 1. An automatic sensitivity adjustment circuit for an in-vehicle device in an ETC system, which is capable of receiving a plurality of applications such as ETC system related radio waves, road condition broadcast radio waves, general radio and FM broadcast radio waves. An optimal application determining means for determining an optimal application at the position where the vehicle in which the vehicle is currently traveling, and a plurality of reference voltages determined for each application are stored, and the application determined by the optimal application determining means or separately Reference voltage generating means for generating a reference voltage suitable for the instructed application is compared with the reference voltage generated by the reference voltage generating means and the reception signal obtained by amplifying and shaping the reception radio wave for each application, and the reception signal is the reference voltage. The in-vehicle device to enable communication when the And means for switching the in-vehicle device to a communicable state by comparing a received signal with a reference voltage generated corresponding to an optimal application at the traveling position, and enabling communication with the optimal application. A sensitivity automatic adjustment circuit for an in-vehicle device in an ETC system. 2. The optimum application determining means is
2. The automatic sensitivity adjustment circuit for a vehicle-mounted device in an ETC system according to claim 1, wherein the application information at the traveling position is obtained from a notice antenna provided on the road. 3. The optimum application determining means is
2. The application information at the traveling position is obtained by a sensor mounted on the bottom surface of the vehicle for receiving information from a loop coil having a road surface embedded therein.
A sensitivity automatic adjustment circuit for an in-vehicle device in the ETC system described in 1. 4. The optimum application determining means is
Pre-stored application location information and GPS (G
(Global Positioning System)
The automatic sensitivity adjustment circuit of the vehicle-mounted device in the ETC system according to claim 1, wherein the optimum application is determined by comparing the current position information acquired by the system. 5. The reference voltage generation means is configured by using an existing CPU in the vehicle-mounted device.
A sensitivity automatic adjustment circuit for an in-vehicle device in the ETC system described in 1. 6. The ETC system according to claim 1, wherein the means for switching the vehicle-mounted device to the communicable state is configured to switch the transmission output to the application at the same time when the vehicle-mounted device is switched to the communicationable state. In-vehicle device sensitivity automatic adjustment circuit in.