JP2007128321A - Etc system and etc on-vehicle unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce vehicle driver's anxiety when passing through an ETC lane by early informing the vehicle driver of the state of received radio wave from a roadside antenna. <P>SOLUTION: An ETC on-vehicle unit 6 configuring an ETC system comprises a patch antenna 11a for directly receiving radio wave rightward (circularly polarized wave signal) from a roadside antenna of a roadside system, a patch antenna 12a for receiving a reflective wave (leftward circularly polarized wave signal) of the radio wave from the roadside antenna from the surface of the road, and an ETC unit 8 for executing data communication with the roadside system from the received signal of the patch antenna 11a and predetermined information to the vehicle driver when the patch antenna 12a receives the reflective wave. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an ETC system and an ETC vehicle-mounted device that use circularly polarized radio signals for data communication operation between road vehicles.

In the ETC (Electronic Toll Collection) system installed on the toll gate island of the toll road, between the roadside antenna and the ETC on-board unit mounted on the vehicle that has entered the billing communication area of the toll gate lane (ETC lane) Basically, when the road-to-vehicle communication is performed and the exchange processing of predetermined ETC data is completed between the road and vehicle, the gate bar of the start controller installed at the exit of the toll gate lane is opened to allow the vehicle to pass. The structure is provided (for example, refer patent document 1).
JP 2004-265047 A

  In the ETC system, when road-to-vehicle communication is performed normally, a message indicating that the vehicle can pass is displayed on the roadside indicator installed at the toll gate, and a guidance sound indicating that fact is displayed. Is notified to the vehicle driver through the ETC vehicle-mounted device. In this case, road-to-vehicle communication is usually completed immediately after the vehicle enters the billing communication area (for example, within several tens of ms). On the other hand, the distance from the front end of the billing communication area to the installation position of the gate bar is generally set to about 10 m or less. Therefore, even if the road-to-vehicle communication is completed as usual, the vehicle When driving at a certain lane at a speed of 20 km recommended as a safe speed, there is a situation that there is only about 2 seconds to the gate bar. For this reason, there is a problem that anxiety on the side of the vehicle driver who is traveling while worrying about opening and closing of the gate bar increases, and it is desirable to take some support measures.

  The present invention has been made in view of the circumstances as described above, and paying attention to the fact that a circularly polarized radio signal is constantly transmitted from the roadside antenna to the ETC billing communication area. An ETC that can quickly notify the vehicle driver who is about to pass the ETC lane that the radio wave signal has been received from the roadside antenna, and can contribute to reducing the anxiety of the vehicle driver during the passage. It is to provide a system and an ETC on-vehicle device.

  According to the ETC system of the first aspect, the radio signal that is constantly transmitted from the roadside antenna disposed above the ETC lane toward the billing communication area is a circularly polarized signal in a predetermined rotation direction. When reflected on a road surface or the like in the billing communication area, the phase is inverted and a circularly polarized signal having a reverse rotation direction is obtained. In other words, if the radio signal transmitted from the roadside antenna to the billing communication area is, for example, a right-handed circularly polarized signal, it is reflected as a left-handed circularly polarized signal when reflected on the road surface or the like. It will reach farther away. On the other hand, the ETC vehicle-mounted device mounted on the vehicle has a first antenna for receiving a radio signal from the roadside antenna directly in the billing communication area, as well as a road surface direction of the radio signal from the roadside antenna. A second antenna for receiving the reflected wave is provided. Therefore, the time point before the vehicle enters the billing communication area on the ETC lane, that is, the control means provided in the ETC on-board unit executes the data communication operation related to toll collection based on the received signal of the first antenna. At a time before the second antenna, the second antenna receives the reflected wave, and accordingly, the control means performs a predetermined notification operation to the vehicle driver.

  As a result, when the vehicle approaches a position a predetermined distance or more ahead of the charging communication area on the ETC lane, a state in which the radio signal from the roadside antenna is received is indicated to the vehicle driver who is about to pass the ETC lane. It will be possible to notify at an early stage, and it will be possible to contribute to the reduction of anxiety on the side of the vehicle driver at the time of passing.

  According to the ETC system of the second aspect, the radio wave signal from the roadside antenna is reflected toward the vehicle traveling on the ETC lane by the inclined structure provided in the billing communication area. Therefore, the reflected wave of the radio wave signal can be efficiently received in the ETC on-vehicle device on the vehicle side, and the notification operation as described above can be reliably performed.

  In the ETC on-vehicle device according to claim 3, in addition to the first antenna for directly receiving a radio signal (circularly polarized signal in a predetermined rotation direction) from the roadside antenna in the billing communication area on the ETC lane The second antenna for receiving the reflected wave from the road surface direction of the radio signal from the roadside antenna is provided, and therefore, the vehicle equipped with the ETC on-board unit before entering the billing communication area on the ETC lane. At the time point, that is, at the time point before the data communication operation related to the toll collection is performed based on the received signal of the first antenna, the second antenna receives the reflected wave, and accordingly, the control means Then, a predetermined notification operation is performed for the vehicle driver.

  As a result, when the vehicle approaches a position a predetermined distance or more ahead of the charging communication area on the ETC lane, a state in which the radio signal from the roadside antenna is received is indicated to the vehicle driver who is about to pass the ETC lane. It will be possible to notify at an early stage, and it will be possible to contribute to the reduction of anxiety on the side of the vehicle driver at the time of passing.

(First embodiment)
A first embodiment of the present invention will be described below with reference to FIGS.
2 (a) and 2 (b) show the basic configuration of the roadside system installed on the toll gate island of the ETC lane in a schematic side view and plan view, and FIG. 3 and FIG. The structure of the main part is shown by a schematic perspective view and a front view.

  2 to 4, the roadside system includes a roadside antenna 3 fixed to the lateral frame portion of the gantry 2 installed so as to straddle the ETC lane 1, and a start controller installed on the exit side of the ETC lane 1. In addition to 4, a vehicle detector, a roadside indicator, a vehicle monitoring camera, a lane server, and the like (not shown) are provided. In this case, when the ETC vehicle-mounted device 6 mounted on the vehicle 5 traveling in the ETC lane 1 enters the charging communication area A set on the ETC lane 1, the roadside antenna 3 is connected to the ETC vehicle-mounted device. 6 is configured to perform an ETC communication operation using radio waves in a high frequency band as a carrier signal. The billing communication area A is determined by the directivity and gain of the roadside antenna 3.

  In this case, the carrier wave signal output from the roadside antenna 3 uses, for example, right-handed circularly polarized wave, and the carrier wave signal including the interrogation signal is always transmitted to the billing communication area A. ing. The ETC in-vehicle device 6 that has received the interrogation signal transmits a link request signal obtained by modulating the received carrier signal to the roadside antenna 3. At this time, in the roadside system, when the link request signal and the approaching vehicle detection information from the vehicle detector (not shown) are received at the same time, the link with the ETC vehicle-mounted device 6 is established and ETC data exchange processing (corresponding to data communication operation for toll collection) is performed, and when the data exchange processing is normally completed, a release signal is transmitted to the ETC on-board unit 6 to disconnect the link. In this configuration, the gate bar 4a of the start controller 4 is opened to allow the vehicle 5 to pass.

  On both sides of the road billing communication area A, a pair of inclined structures 7, 7 configured to reflect radio signals from the roadside antenna 3 toward the vehicle 5 in a state of being located in front of the billing communication area A. Is provided. That is, as shown in FIGS. 3 and 4, these inclined structures 7 are long wedge-shaped members arranged in parallel along the ETC lane 1, and the roadside antenna 3 is provided on each upper surface. In order to reduce the incident angle of the radio signal from the side, the tapered surface 7a is formed so as to be gradually lowered from the base side of the gantry 2 toward the approaching vehicle 5 side and inclined toward the center line of the ETC lane 1 Has been. Thereby, the radio signal output from the roadside antenna 3 is reflected by the tapered surface 7a of the inclined structure 7, and the reflected wave is directed toward the vehicle 5 located in front of the billing communication area A. Yes. In this case, the radio wave signal output from the roadside antenna 3 (right-handed circularly polarized signal: indicated by a solid line in FIGS. 2 and 4) is reflected by the taper surface 7a, and the left-handed circularly polarized signal (FIG. 2, The phase is inverted (indicated by a broken line in FIG. 4).

FIG. 1 schematically shows a basic configuration example of the ETC vehicle-mounted device 6, which will be described below.
That is, the ETC unit 8 (corresponding to the control means) that is the main body of the ETC vehicle-mounted device 6 is housed in the room mirror 9 of the vehicle 5. An antenna unit 11 connected to the ETC unit 8 by a coaxial cable 10 is attached to the inside of a windshield (not shown) of the vehicle 5. This antenna unit 11 is for performing an ETC communication operation with the roadside antenna 3, and when the vehicle 5 enters the billing communication area A, a radio signal (right-handed circular polarization) from the roadside antenna 3. Signal) can be received directly. The patch antenna 11a (corresponding to the first antenna) built in the antenna unit 11 is connected to a transmission / reception circuit (including a matching circuit, amplifier, modulation / demodulation circuit, etc.) provided in the ETC unit 8 (not shown). Yes.

  The auxiliary antenna unit 12 is housed in the room mirror 9, and is a patch antenna 12a having a specification and an arrangement capable of receiving a reflected wave (left-handed circularly polarized signal) from the road surface direction of the radio signal from the roadside antenna 3. (Corresponding to the second antenna) and a receiving circuit 12b that amplifies and detects the received signal of the patch antenna 12a, and the received signal is given to the ETC unit 8 via the communication cable 13. It is supposed to be. The patch antenna 12a is tilted so that the reflected wave of the radio wave signal from the roadside antenna 3 on the inclined structure 7 can be efficiently received when the vehicle 5 travels to a position before the charging communication area A. Are arranged in a shape.

  The antenna unit 11 and the auxiliary antenna unit 12 are configured to have good cross polarization discrimination (cross polarization characteristics), so that a circular polarization signal (main polarization) to be received is received. Is efficiently received, and the cross polarization with respect to the main polarization is not received as much as possible.

  In the flowchart of FIG. 5, only the contents related to the gist of the present invention are shown in the control contents by the ETC unit 8, and this will be described below together with related operations. In FIG. 5, a radio wave signal (right-handed circularly polarized signal) received from the roadside antenna 3 received by the antenna unit 11 is a “direct wave”, and a reflected wave of the radiowave signal received from the roadside antenna 3 received by the auxiliary antenna unit 12. (Left-handed circularly polarized signal) is described as “reflected wave”.

  In FIG. 5, the ETC unit 8 stands by until a reflected wave or a direct wave is received (steps S1 and S2). When the reflected wave is received, the ETC unit 8 is in a state of receiving a radio signal from the roadside antenna 3. Notify by the output from the built-in speaker that does not (step S3). That is, when the vehicle 5 traveling toward the charging communication area A in the ETC lane 1 reaches the reflected wave receivable range B (see FIG. 2) in front of the charging communication area A, the driver of the vehicle 5 On the other hand, a notification that the radio signal from the roadside antenna 3 has been received is issued. Note that the notification sound at this time has a soft content that does not surprise the vehicle driver or give a sense of tension or suspiciousness.

  After the execution of step S3, it is determined whether or not the reception of the reflected wave is continued (step S4). If it is continued, step S3 is continuously executed. That is, during the period until the vehicle 5 that has reached the reflected wave receivable range B enters the billing communication area A, the notification sound is continuously output. However, it is not necessary to continuously output the notification sound, and a configuration in which the notification sound is continued for a predetermined time is also possible.

  On the other hand, when the reception of the reflected wave is completed (“NO” in step S4), that is, when it is assumed that the vehicle 5 has entered the billing communication area A, the process waits until the direct wave is received. (Step S5). When a direct wave is received (when the vehicle 5 enters the billing communication area A), an ETC communication operation with the roadside antenna 3 is established (a link with the roadside system is established and ETC data exchange processing is performed). When the processing is completed, the ETC control routine S6 for performing the operation of receiving the release signal from the roadside system and disconnecting the link is executed, and then the process returns to the initial state.

  It should be noted that when the vehicle 5 is traveling at a predetermined speed or more and the standby state in Step S5 (the state in which the direct wave is not received after receiving the reflected wave) continues for a predetermined time or longer, the initial state is maintained. It is good also as a structure which returns to an initial state after performing the alarm operation | movement which alert | reports abnormality generation through a built-in speaker, or a structure which returns to a state (step S1).

  On the other hand, if “YES” is determined in step S2, that is, if a direct wave is received without receiving a reflected wave (the vehicle 5 does not receive a reflected wave while traveling in the reflected wave receivable range B). In the case of entering into the billing communication area A), the ETC control routine S6 is executed as it is, and then it returns to the initial state.

  In short, according to the above-described configuration of the present embodiment, the radio signal that is always transmitted from the roadside antenna 3 toward the charging communication area A on the ETC lane 1 is a right-hand circularly polarized signal. When reflected by the road surface in the area A or the tapered surface 7a of the inclined structure 7, it reaches a position farther from the billing communication area A as a left-handed circularly polarized signal whose phase is inverted.

  On the other hand, the ETC vehicle-mounted device 6 mounted on the vehicle 5 has an antenna unit 11 including a patch antenna 11a for directly receiving a radio signal from the roadside antenna 3 in the billing communication area A. An auxiliary antenna unit 12 including a patch antenna 12a that receives a reflected wave from the road surface direction of a radio signal from the antenna 3 is provided. Therefore, the time point before the vehicle 5 traveling in the ETC lane 1 enters the billing communication area A (the time point when the vehicle 5 is traveling in the reflected wave receivable range B), that is, the ETC unit 8 in the ETC vehicle-mounted device 6. However, the auxiliary antenna unit 12 receives the reflected wave before the data communication operation related to toll collection is performed based on the received signal of the antenna unit 11, and the ETC unit 8 responds accordingly. The vehicle driver is notified that the radio signal from the roadside antenna 3 has been received.

  As a result, when the vehicle 5 reaches a position a predetermined distance or more before the charging communication area A on the ETC lane 1, the vehicle that is about to pass through the ETC lane 1 in a state in which the radio signal is received from the roadside antenna 3 5 can be notified to the driver at an early stage, and the vehicle driver can be reduced in anxiety when passing the vehicle.

  Further, on both sides of the billing communication area A, a pair of inclined structures 7 configured to reflect the radio signal from the roadside antenna 3 toward the vehicle 5 in a state of being located in front of the billing communication area A, 7 is provided, the reflected wave of the radio wave signal from the roadside antenna 3 can be efficiently received by the ETC vehicle-mounted device 6, and the notification operation as described above can be performed reliably. In addition, there is an advantage that a system configuration in which another antenna such as a well-known notice antenna is provided in front of the billing communication area A to perform such notification is unnecessary.

(Second Embodiment)
FIG. 6 shows a second embodiment of the present invention that achieves a power saving effect in addition to the same effects as those of the first embodiment, and only the portions different from the first embodiment will be described below.
That is, the second embodiment is characterized by the contents of control by the ETC unit 8, and only the part related to the gist of the present invention is shown in the flowchart of FIG. In FIG. 6, the ETC unit 8 switches the ETC on-board unit 6 to the standby mode (low power consumption mode in which only the reception functions of the patch antennas 11a and 12a are activated) after power-on (step S0). As in the first embodiment, steps S1 and S2 are performed to wait until a reflected wave or a direct wave is received.

  When the reflected wave is received (“YES” in step S1), after executing the step S1a for canceling the standby mode and wake-up, the steps S3 to S5 and the ETC control routine S6 are executed, and the direct wave is received. When ("YES" in step S2), the ETC control routine S6 is executed after executing step S2a for canceling the standby mode and wake-up. And after execution of ETC control routine S6 is complete | finished, after performing step S7 which switches the ETC onboard equipment 6 to standby mode again, it returns to step S1.

(Other embodiments)
In addition, the present invention is not limited to the above-described embodiments, and can be modified or expanded as follows, for example.
A first antenna (patch antenna 11a) for receiving a direct wave (right-hand circularly polarized wave in the embodiment) and a second antenna (patch antenna 12a) for receiving a reflected wave (left-handed circularly polarized wave in the embodiment) Can be shared by a single antenna for both polarizations having a large directivity angle. Further, the inclined structure 7 may be provided as necessary.

The figure which shows typically the example of a basic composition of the ETC onboard equipment by 1st Example of this invention. Schematic side view and plan view showing the basic configuration of the roadside system Schematic perspective view showing the main part of the roadside system Schematic front view showing the main parts of the roadside system Flow chart showing control contents by ETC unit FIG. 5 equivalent diagram showing a second embodiment of the present invention.

Explanation of symbols

  1 is an ETC lane, 3 is a roadside antenna, 4 is a start controller, 5 is a vehicle, 6 is an ETC on-board unit, 7 is an inclined structure, 7a is a tapered surface, 8 is an ETC unit (control means), and 11 is an antenna Unit 11a is a patch antenna (first antenna), 12 is an auxiliary antenna unit, 12a is a patch antenna (second antenna), and A is a charging communication area.

Claims (3)

A road-side antenna that is arranged above the ETC lane and constantly transmits a radio signal composed of a circularly polarized signal in a predetermined rotation direction toward a billing communication area set in the ETC lane, the road-side antenna and the billing communication In an ETC system that performs data communication operations related to toll collection with an ETC on-board unit mounted on a vehicle passing through an area,
On the ETC on-board unit side,
A first antenna that directly receives a radio signal from the roadside antenna;
A second antenna for receiving a reflected wave from the road surface direction of the radio signal from the roadside antenna;
The data communication operation is performed with the roadside antenna based on a reception signal of the first antenna, and a predetermined value is given to a vehicle driver when the second antenna receives the reflected wave. Control means for executing a notification operation;
An ETC system characterized by providing   The billing communication area is provided with an inclined structure that reflects a radio signal from the roadside antenna toward the vehicle traveling on the ETC lane toward the billing communication area. The ETC system according to claim 1. When the host vehicle travels in the billing communication area on the ETC lane, the ETC in-vehicle performs a data communication operation related to toll collection with a roadside antenna that constantly transmits a radio signal composed of a circularly polarized signal in a predetermined rotation direction. In the vessel
A first antenna that directly receives a radio signal from the roadside antenna;
A second antenna for receiving a reflected wave from the road surface direction of the radio signal from the roadside antenna;
A data communication operation through the roadside antenna is performed based on a reception signal of the first antenna, and a predetermined notification operation is performed to a vehicle driver when the second antenna receives the reflected wave. Control means to execute;
ETC in-vehicle device characterized by comprising.

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