JP2010140375A - Passive type onboard device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enhance electric wave intensity of an uplink output from a passive type onboard device without changing a specification of a roadside apparatus. <P>SOLUTION: A modulated wave MW and a carrier wave CW output from a fixed station antenna 3 are received by a transmission/reception antenna 101 of this onboard device 100, pass a semi-active circuit 120 as they are, and thereafter are transmitted to an onboard device circuit 110. The onboard device circuit 110 reflects and modulates the carrier wave CW to create an onboard device output electric wave UW for sending-back, and the onboard device output electric wave UW is amplified in the semi-active circuit 120 and is transmitted toward the fixed station antenna 3 from the transmission/reception antenna 101. By interposing such the semi-active circuit 120, the electric wave intensity of the uplink is enhanced. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a passive vehicle-mounted device, and is devised so that the radio wave intensity output from the vehicle-mounted device can be increased without changing the radio wave intensity output from the roadside device.

Non-stop toll collection systems include an automatic toll collection (ETC) system and an electronic road pricing (ERP) system.
In such a non-stop toll collection system, charging processing is performed by performing wireless communication between a roadside device installed on the ground side and a vehicle-mounted device mounted on the vehicle, and the vehicle travels nonstop. Can do.

As the vehicle-mounted device, there are an active vehicle-mounted device having an oscillator and a passive vehicle-mounted device having no oscillator.
When a passive type vehicle-mounted device receives a radio wave transmitted from a roadside device (downlink radio wave), it reflects and modulates this radio wave, and uses the reflected and modulated radio wave as an uplink radio wave on the roadside. Sending (returning) to the device.

Here, an electronic road pricing (ERP) system using a passive vehicle-mounted device will be described.
The ERP system is a system that charges a vehicle that enters a predetermined restricted area (for example, a city center). By charging in this way, traffic inflows into restricted areas (such as city centers) are controlled to ease traffic jams and secure financial resources for traffic maintenance.

In the ERP system, as shown in FIG. 5, a gantry 2, which is a portal structure, is installed across the road 1, and the gantry 2 is provided with a fixed station antenna 3.
The vehicle 4 includes a passive vehicle-mounted device 5.
When the vehicle 4 travels under the gantry 2, communication is performed between the fixed station antenna 3 and the vehicle-mounted device 5 using radio waves in a quasi-microwave band (for example, 2360 MHz), and automatic charging is performed in a non-stop state.

Here, the communication state between the fixed station antenna 3 and the vehicle-mounted device 5 will be described with reference to FIG. 6 which is a time chart.
From the fixed station antenna 3, a modulated wave MW and a carrier wave (non-modulated wave) CW following the modulated wave MW are transmitted as radio waves for one communication slot. The modulated wave MW includes information indicating that it is the entrance of the ERP system as information.
The in-vehicle device 5 determines that the entrance to the ERP system has been reached by receiving and detecting the modulated wave MW. Therefore, when receiving the carrier wave CW, the vehicle-mounted device 5 reflects and modulates the carrier wave CW and outputs it as the vehicle-mounted device output radio wave UW. The onboard unit output radio wave UW includes ID information of the onboard unit 5 as information.
The fixed station antenna 3 receives the vehicle-mounted device output radio wave UW, and charging processing is performed.

JP-A-8-221623

Since the passive vehicle-mounted device 5 described above does not have an oscillation circuit, there is an advantage that the device configuration is simple and inexpensive.
However, in this passive vehicle-mounted device 5, the carrier wave CW transmitted from the fixed station antenna 3 is electrically reflected as it is and returned to the fixed station antenna 3 as the vehicle-mounted device output radio wave UW. The power of the output radio wave UW is weak.
For this reason, if a radio wave close to the frequency of the radio wave used in the ERP system enters from another radio system (for example, a wide area wireless LAN), radio wave interference occurs and the billing process cannot be performed reliably. There are concerns.

  If the intensity of the radio wave output from the fixed station antenna 3 is increased, the on-board unit output radio wave UW is also increased accordingly, and it is considered that the problem of radio wave interference can be prevented. The intensity of the output radio wave cannot be increased.

The reason is explained as follows.
When an unauthorized vehicle that cannot be properly charged due to an unauthorized card being inserted into the vehicle-mounted device or due to a lack of balance, a system for detecting such an unauthorized vehicle, It is installed close to the gantry 2.
Even in this system for detecting an unauthorized vehicle, it is determined whether the vehicle is an unauthorized vehicle by transmitting an electric wave toward the vehicle and receiving a return electric wave from the vehicle or the vehicle-mounted device mounted on the vehicle. .

  At this time, if the intensity of the radio wave output from the fixed station antenna 3 is increased, the radio wave of the system for detecting the unauthorized vehicle is disturbed, and the unauthorized vehicle cannot be detected. For this reason, the intensity of the radio wave output from the fixed station antenna 3 cannot be increased.

  In addition, a large number of in-vehicle devices are already in widespread use, and such in-vehicle devices that are actually in operation have a device configuration that corresponds to the current radio wave intensity. This is because it may become unstable.

  In view of the above-described conventional technology, the present invention is a passive type vehicle-mounted device that can increase the intensity of the vehicle-mounted device output radio wave returned from the vehicle-mounted device to the road-side device without changing the roadside device (fixed station antenna). The purpose is to provide a vessel.

The configuration of the present invention for solving the above problems is as follows.
An antenna for receiving radio waves transmitted from roadside devices;
An in-vehicle device circuit for generating a return radio wave by reflecting and modulating the radio wave received by the antenna, and outputting the return radio wave from the antenna;
In a passive vehicle-mounted device having
A semi-active circuit is provided that transmits the radio wave received by the antenna as it is to the on-vehicle device and amplifies the return radio wave output from the on-vehicle device and then transmits it to the antenna. To do.

The configuration of the present invention is as follows.
In the vehicle-mounted device circuit,
A control unit that outputs a wake-up signal when radio waves received by the antenna are input;
And a regulator for supplying power to the semi-active circuit when the wake-up signal is output.

The configuration of the present invention is as follows.
The semi-active circuit is
It has a first port, a second port, and a third port, the radio wave input to the first port is output from the second port, the radio wave input to the second port is output to the third port, and the third port First and second circulators having a characteristic of outputting the radio wave input to the first port;
An amplifier that amplifies radio waves,
The first circulator is interposed in a transmission line that connects the antenna and the vehicle-mounted device circuit, the first port is disposed on the antenna side, and the second port is disposed on the vehicle-mounted device circuit side. Has been
The second circulator is interposed on the vehicle-mounted device side of the transmission line from the position where the first circulator is interposed, the first port is disposed on the antenna side, and the second port is mounted on the vehicle. Placed on the circuit side,
The amplifier has an input terminal connected to the third port of the second circulator and an output terminal connected to the third port of the first circulator.

The configuration of the present invention is as follows.
The first and second circulators are:
A ring directional coupler formed by a microstrip line having a rectangular frame shape, a plurality of periodic stubs formed by microstrip lines loaded on each side of the ring directional coupler, and the ring The load-type ring directional coupler is composed of four port terminals formed by microstrip lines formed at four corners of the directional coupler and a terminating resistor that terminates one of the port terminals. And

  In the present invention, between the antenna and the vehicle-mounted device circuit, the downlink radio wave received by the antenna is directly transmitted to the vehicle-mounted device circuit, and the uplink radio wave output from the vehicle-mounted device circuit is amplified. Since the semi-active circuit for transmitting to the antenna is provided, the radio field strength of the uplink returned from the vehicle-mounted device to the antenna can be increased without changing the specifications of the roadside device. As a result, uplink radio waves are not interfered with radio waves of other radio systems, and reliable charging processing can be performed.

  Furthermore, as a circulator for use in a semi-active circuit, a small and heat-resistant ring-type directional coupler composed of a microstrip line can be used to reduce the size of the semi-active circuit and thus the vehicle-mounted device. Can be realized.

  Hereinafter, the best mode for carrying out the present invention will be described in detail based on examples.

FIG. 1 shows a passive vehicle-mounted device 100 according to a first embodiment of the present invention. The vehicle-mounted device 100 includes a transmission / reception antenna 101, a vehicle-mounted device circuit 110, and a semi-active circuit 120.
The transmission / reception antenna 101, the vehicle-mounted device circuit 110, and the semi-active circuit 120 are electromagnetically connected by a transmission line L.

  Of the on-vehicle device 100, the on-vehicle device antenna 101 and the on-vehicle device circuit 110 are components (component circuits) that are also provided in a conventional on-vehicle device. The vehicle-mounted device 100 according to the first embodiment is characterized in that a semi-active circuit 120 is newly provided between the vehicle-mounted device antenna 101 and the vehicle-mounted device circuit 110.

  The transmitting / receiving antenna 101 receives the modulated wave MW and the carrier wave CW transmitted from the fixed station antenna 3 that is a roadside device, and directs the onboard unit output radio wave UW output from the onboard unit circuit 110 toward the fixed station antenna 3. Send.

Although the detailed configuration will be described later, the semi-active circuit 120 transmits the modulated wave MW and the carrier wave CW received by the transmission / reception antenna 101 as they are to be transmitted to the vehicle-mounted device circuit 110, and is also output from the vehicle-mounted device circuit 110. The output radio wave UW is amplified and transmitted to the transmitting / receiving antenna 101.
That is, the semi-active circuit 120 has a characteristic in which the downlink radio wave is transmitted as it is and the uplink radio wave is amplified before being transmitted.
A specific configuration example of the semi-active circuit 120 will be described in Examples 3 and 4 later.

  The vehicle-mounted device circuit 110 includes a switch circuit 111, a detector 112, an amplifier 113, a modulator 114, and a control unit (CPU) 115.

  The modulator 114 is configured by forming a copper foil transmission line on a substrate. The transmission line has a rectangular shape, and the length in the direction of transmitting radio waves is λ / 4 where λ is the wavelength of the carrier wave CW. Therefore, when the carrier wave CW is incident on the modulator 114, that is, the transmission line and then reflected, the phase of the reflected carrier wave CW is shifted from the phase at the time of incidence by λ / 2 (the phase is inverted).

  When the modulated wave MW and the carrier wave CW transmitted from the fixed station antenna 3 are received by the transmission / reception antenna 101, the received modulated wave MW and the carrier wave CW are transmitted to the vehicle-mounted device circuit 110 through the semi-active circuit 120. The

  When the modulated wave MW is input to the vehicle-mounted device circuit 110, the modulated wave MW is input to the detector 112 via the switch circuit 111. The detector 112 detects the modulated wave MW to obtain received data a, and the received data a is amplified by the amplifier 113 and then input to the control unit 115.

  The control unit 115 receives the reception data a to determine that the vehicle has reached the entrance of the ERP system, and outputs transmission data b that is a digital signal. The transmission data b includes ID information of the on-vehicle device 100 and the like.

The transmission data b is sent to the switch circuit 111, and the switch circuit 111 performs a switching operation according to high (H) and low (L) of the transmission data b.
When the switch circuit 111 is in an open state (OFF state), the carrier wave CW input to the vehicle-mounted device circuit 110 is reflected by the switch circuit 111, and the phase of the reflected radio wave is in phase with the phase at the time of input.
When the switch circuit 111 is turned on (ON state), the carrier wave CW input to the vehicle-mounted device circuit 110 is reflected by the modulator (transmission line) 114, and the phase of the reflected radio wave is the phase at the time of input. And in reverse phase.

  In this way, when the switching circuit 111 is switched according to the transmission data b, the phase of the reflected radio wave is changed due to the reflection position of the carrier wave CW being changed, and two-phase shift keying (BPSK: Binary phase) is performed. -shift keying). The reflected radio wave generated by the two-phase shift modulation of the carrier wave CW is output from the on-vehicle device circuit 110 as the on-vehicle device output radio wave UW.

The onboard equipment output radio wave UW output from the onboard equipment circuit 110 is amplified by the semi-active circuit 120 and then transmitted to the transmission / reception antenna 101 and transmitted (returned) from the transmission / reception antenna 101.
Since the in-vehicle device output radio wave UW is amplified by the semi-active circuit 120 and the radio wave intensity is increased, even if the radio wave invades from another system (for example, a wide area wireless LAN), it interferes with the invading radio wave. Without being received by the fixed station antenna 3. For this reason, reliable billing processing can be performed.

  In the vehicle-mounted device 100 according to the first embodiment, the transmission / reception antenna 101 and the vehicle-mounted device circuit 110 are component parts (component circuits) that are also used in a conventional vehicle-mounted device, and thus the transmission / reception antenna 101 and The in-vehicle device circuit 110 can use a conventional design technique as it is. Therefore, it is possible to utilize the experience and know-how of highly reliable design / manufacturing that has been built with the prior art. As a result, the vehicle-mounted device 100 according to the first embodiment is also a highly reliable product.

In addition, since the specification of the roadside equipment such as the fixed station antenna 3 is not changed, a conventional vehicle-mounted device that is already in operation can be used as it is.
Furthermore, since the radio wave intensity output from the fixed station antenna 3 is not increased, it does not adversely affect the system for detecting unauthorized vehicles.

  Next, a passive vehicle-mounted device 100a according to a second embodiment of the present invention will be described with reference to FIG.

  The on-vehicle device 100a according to the second embodiment is obtained by adding a wake-up function to the on-vehicle device 100 according to the first embodiment.

  The on-vehicle device circuit 110a of the on-vehicle device 100a includes a regulator 116. The regulator 116 has a function of supplying the voltage-adjusted power to the amplifier 113 and other power consuming elements in the vehicle-mounted device circuit 110a and to the semi-active circuit 120.

  The control unit 115 has a function of outputting the wake-up signal c to the regulator 116 when the modulation signal MW is input to the vehicle-mounted device circuit 110 a and the reception data a is input from the detector 112. The control unit 115 continuously outputs the wake-up signal c during the period in which the radio waves MW and CW received by the transmission / reception antenna 101 are input to the vehicle-mounted device circuit 110.

  The regulator 116 stops the power supply when the wake-up signal c is not output from the control unit 115, and when the wake-up signal c is output from the control unit 115, the amplifier 113 in the vehicle-mounted device circuit 110a, etc. The voltage-adjusted power is supplied to the semi-active circuit 120.

  For this reason, power is supplied to the semi-active circuit 120 only during a period in which radio waves are transmitted and received between the vehicle-mounted device 100a and the fixed station antenna 3, and power is supplied to the semi-active circuit 120 in other periods. It is not supplied. For this reason, even if the semi-active circuit 120 is provided, power consumption is not wasted and power consumption can be reduced, and overdischarge of the power source (vehicle battery) can be prevented.

  In addition, since the structure of another part is the same as that of Example 1, the same code | symbol is attached | subjected to the part which performs the same function, and the overlapping description is abbreviate | omitted.

Next, a specific configuration of the semi-active circuit 120 used in the vehicle-mounted devices 100 and 100a according to the first and second embodiments will be described with reference to FIG.
As shown in FIG. 3, the semi-active circuit 120 is arranged in a state of being interposed in a transmission line L that connects the transmitting / receiving antenna 101 and the vehicle-mounted device circuit 110 (or 110a).

The semi-active circuit 120 includes two three-port circulators 121 and 122 and an amplifier 123.
As the circulators 121 and 122, a general-purpose circulator manufactured by a magnetized ferrite material or a loaded ring directional coupler formed by a microstrip line as described later can be used.

  The first circulator 121 has a first port # 11, a second port # 12, and a third port # 13, and outputs a radio wave input to the first port # 11 from the second port # 12. The radio waves input to the second port # 12 are output to the third port # 13, and the radio waves input to the third port # 13 are output to the first port # 11.

  Similarly, the second circulator 122 has a first port # 21, a second port # 22, and a third port # 23. The radio wave input to the first port # 21 is transmitted to the second port # 22. Output from the second port # 22 to the third port # 23, and output from the third port # 23 to the first port # 21.

The first circulator 121 is interposed in the transmission line L, the first port # 11 is disposed on the transmission / reception antenna 101 side, and the second port # 12 is disposed on the in-vehicle device circuit 110 (110a) side. .
The second circulator 122 is interposed on the in-vehicle device circuit 110 (110a) side of the transmission line L from the position where the first circulator 121 is interposed, and the first port # 21 is disposed on the transmission / reception antenna 101 side. The second port # 22 is arranged on the vehicle-mounted device circuit 110 (110a) side.

  The amplifier 123 having a function of amplifying radio waves has an input terminal connected to the third port # 23 of the second circulator 122 and an output terminal connected to the third port # 13 of the first circulator 121. .

  In the semi-active circuit 120 having such a configuration, the modulated wave MW and the carrier wave CW received by the transmitting / receiving antenna 101 are transmitted from the first port # 11 of the first circulator 121 to the second port # 12 of the first circulator 121 to the second port. The first circulator 122 is transmitted via the first port # 21 → the second port # 22 of the second circulator 122. That is, the modulated wave MW and the carrier wave CW received by the transmission / reception antenna 101 pass through the semi-active circuit 120 and are transmitted to the vehicle-mounted device circuit 110 (110a). At this time, there is almost no transmission loss in the circulators 121 and 122.

The onboard unit output radio wave UW output from the onboard unit circuit 110 (110a) is the second port # 22 of the second circulator 122 → the third port # 23 of the second circulator 122 → the amplifier 123 → the first circulator 121. Is transmitted toward the transmitting / receiving antenna 101 through a path of the third port # 13 → the first port # 11 of the first circulator 121.
At this time, since the onboard unit output radio wave UW output from the onboard unit circuit 110 (110a) is amplified by the amplifier 123, the amplified onboard unit output radio wave UW having strong radio field intensity is transmitted from the transmission / reception antenna 101. .

  Next, a loaded ring directional coupler 200 formed by a microstrip line that can be used as the circulators 121 and 122 will be described with reference to FIG.

  A loaded ring directional coupler 200 shown in FIG. 4 is used as the circulators 121 and 122 shown in FIG.

The loaded ring directional coupler 200 is configured by forming a copper foil microstrip line on a substrate.
More specifically, the loaded ring directional coupler 200 includes a ring directional coupler 201 having a rectangular frame shape and a number of periodic stubs loaded on each side of the ring directional coupler 201. 202, four port terminals 203a, 203b, 203c, and 203d formed at the four corners of the ring directional coupler 200, and a termination resistor 204 that terminates the port terminal 203d.

The length of one side of the directional coupler 201 is λ / 4 where λ is the wavelength of the radio waves MW, CW, and UW.
The end portions of the four port terminals 203a, 203b, 203c, and 203d are first to fourth ports # 1 to # 4.

The first port # 1, the second port # 2, and the third port # 3 of the loaded ring directional coupler 200 are connected to the first port # 11, the second port # 12, and the third port # 3 of the first circulator 121, respectively. It corresponds to the port # 13 and also corresponds to the first port # 21, the second port # 22, and the third port # 23 of the second circulator 122.
That is, the loaded ring directional coupler 200 outputs the radio wave input to the first port # 1 from the second port # 2, and outputs the radio wave input to the second port # 2 to the third port # 3. It has characteristics as a circulator that outputs the radio wave input to the third port # 3 to the first port # 1.

In this loaded type ring directional coupler 200, since the periodic stub 202 is loaded on the ring directional coupler 201, the overall size is larger than that of the ring directional coupler not loaded with the periodic stub. Is getting smaller.
The load-type ring directional coupler 200 is formed by forming a copper foil microstrip line on a substrate. Incidentally, in a general-purpose circulator made of magnetized ferrite, it is strong against heat. There is a problem that its magnetic characteristics are easily deteriorated by heat.

If the small loaded ring directional coupler 200 having such a configuration is employed as the circulators 121 and 122 of the semi-active circuit 120, the semi-active circuit 120 can be downsized, and the on-vehicle device 100 (100a) can be downsized. Can be achieved.
Moreover, since the load-type ring directional coupler 200 is resistant to heat, the onboard device 100 (100a) that is thermally strong can be manufactured.

  The present invention can be applied as it is to a passive vehicle-mounted device used in an ETC system as well as a passive vehicle-mounted device used in an ERP system.

The block block diagram which shows the passive vehicle equipment based on Example 1 of this invention. The block block diagram which shows the passive vehicle equipment based on Example 2 of this invention. The block block diagram which shows the semi-active circuit used in Example 1, 2 of this invention. The circuit block diagram which shows the loading type | mold directional coupler used as a circulator of a semi-active circuit. The schematic diagram which shows an ERP system. Explanatory drawing which shows the communication state in an ERP system.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Road 2 Gantry 3 Fixed station antenna 4 Vehicle 5 Onboard equipment 100,100a Onboard equipment 101 Transmission / reception antenna 110,110a Onboard equipment 111 Switch circuit 112 Detector 113 Amplifier 114 Modulator 115 Control part 116 Regulator 120 Semi-active circuit 121,122 Circulator 123 Amplifier 200 Loaded ring directional coupler 201 Ring directional coupler 202 Stub 203a-203d Port terminal 204 Termination resistance L Transmission line

Claims (4)

An antenna for receiving radio waves transmitted from roadside devices;
An in-vehicle device circuit for generating a return radio wave by reflecting and modulating the radio wave received by the antenna, and outputting the return radio wave from the antenna;
In a passive vehicle-mounted device having
A semi-active circuit is provided that transmits the radio wave received by the antenna as it is to the on-vehicle device and amplifies the return radio wave output from the on-vehicle device and then transmits it to the antenna. Passive in-vehicle device. In the vehicle-mounted device circuit,
A control unit that outputs a wake-up signal when radio waves received by the antenna are input;
When the wake-up signal is output, a regulator that supplies power to the semi-active circuit;
The passive vehicle-mounted device according to claim 1, comprising: The semi-active circuit is:
A first port, a second port, and a third port; a radio wave input to the first port is output from the second port; a radio wave input to the second port is output to the third port; First and second circulators having a characteristic of outputting the radio wave input to the first port;
An amplifier that amplifies radio waves,
The first circulator is interposed in a transmission line that connects the antenna and the vehicle-mounted device circuit, the first port is disposed on the antenna side, and the second port is disposed on the vehicle-mounted device circuit side. Has been
The second circulator is interposed on the vehicle-mounted device side of the transmission line from the position where the first circulator is interposed, the first port is disposed on the antenna side, and the second port is mounted on the vehicle. Placed on the circuit side,
The amplifier has an input terminal connected to the third port of the second circulator, and an output terminal connected to the third port of the first circulator.
The passive vehicle-mounted device according to claim 1 or 2, characterized in that The first and second circulators are:
A ring directional coupler formed by a microstrip line having a rectangular frame shape, a plurality of periodic stubs formed by microstrip lines loaded on each side of the ring directional coupler, and the ring The load-type ring directional coupler is composed of four port terminals formed by microstrip lines formed at four corners of the directional coupler and a terminating resistor that terminates one of the port terminals. The passive vehicle-mounted device according to claim 3.

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