JP6094018B2 - Light beacon, incident light emission method and light emission circuit for vehicle detection - Google Patents

Description

The present invention relates to an optical beacon having both an optical communication function and a vehicle sensing function, a method for emitting incident light for vehicle sensing using the optical beacon, and a light emitting circuit used for the optical beacon .

As a traffic information service using a road-to-vehicle communication system, so-called VICS (Vehicle Information and Communication System: registered trademark of Road Traffic Information Communication System Center) using optical beacons, radio beacons or FM multiplex broadcasting has already been developed. ing.
Among these, the optical beacon employs optical communication using near infrared rays as a communication medium, and is capable of bidirectional communication with the in-vehicle device. Specifically, uplink information including travel time information between beacons held by the vehicle is transmitted from the in-vehicle device to the infrastructure-side optical beacon.

Conversely, downlink information including traffic jam information, section travel time information, event regulation information, lane notification information, and the like is transmitted from the optical beacon to the in-vehicle device.
For this reason, the optical beacon includes a light projecting / receiving device (also referred to as a “beacon head”) that projects and receives an optical signal with the vehicle-mounted device. A transmission / reception unit for optical communication having a light-emitting element that is transmitted toward the road and a light-receiving element that receives uplink light transmitted from the vehicle-mounted device is mounted.

Further, as this type of optical beacon, there is an optical beacon having both a vehicle sensing function for counting the number of vehicles passing a light vehicle or more in addition to an optical communication function with an in-vehicle device (see, for example, Patent Documents 1 and 2). ).
In this optical beacon having a vehicle sensing function, a light emitting element that transmits incident light composed of pulsed light to a downstream side of a downlink region where an in-vehicle device can receive downlink light, and a light receiving element that receives reflected light of the incident light A sensor unit for vehicle detection having the above is further mounted in the housing of the projector / receiver.

JP 2008-242914 A JP 2011-242835 A

The conventional optical beacon is usually operated so that the wavelength of incident light is the same as or substantially the same as the wavelength of downlink light. For this reason, particularly in the part from the downstream side of the downlink region, the incident light for vehicle detection interferes with the downlink light, and the in-vehicle device cannot properly receive the downlink light, and downlink communication is hindered. There was a risk.
In particular, in order to increase the certainty of reception of the downlink light by the in-vehicle device, when the downlink region is expanded downstream, the possibility that the incident light interferes with the downlink light increases.

  SUMMARY OF THE INVENTION The present invention has been made in view of the above-described conventional problems, and it is an object of the present invention to ensure downward communication in road-to-vehicle communication using an optical beacon having both an optical communication function and a vehicle sensing function.

  (1) The present invention is an optical beacon having both an optical communication function and a vehicle sensing function, and a light emitting member for optical communication that transmits downlink light toward a road, and an in-vehicle device receives the downlink light. A vehicle-sensing light-emitting member that transmits vehicle-sensing incident light downstream of a possible downlink region, and the upstream side of the vehicle-sensing light-emitting member is shielded to diffuse the incident light upstream. And a shielding member for suppressing the above.

According to the optical beacon of the present invention, the shielding member shields the upstream side of the light emitting member for vehicle detection and suppresses the diffusion of the incident light to the upstream side. Therefore, in the portion from the downstream side of the downlink region. The incident light can be prevented or reduced from interfering with the downlink light.
For this reason, in road-to-vehicle communication using an optical beacon that has both an optical communication function and a vehicle sensing function, it is suppressed that the downstream communication is inhibited by the incident light for vehicle detection, and the downward communication is further improved. It can be done reliably.

  In addition, the above-mentioned “shielding member that suppresses the diffusion of incident light to the upstream side” means that a shielding member that can achieve the suppression as a result is sufficient, and the designer and manufacturer of the optical beacon. The “intention” of suppression by the user or the like does not matter.

(2) In the optical beacon of the present invention, the shielding member only needs to have a structure capable of optically shielding the upstream side of the light-emitting member for vehicle detection, and may have any shape such as a cylindrical member or a plate member that does not transmit incident light. A member can be employed.
For example, when the vehicle-sensing light-emitting member has a plurality of light-emitting elements arranged two-dimensionally in a column in the vehicle traveling direction and a row in the road width direction, the shielding member is shielded on the upstream side of the row, respectively. In this way, it is preferable to use a plurality of shielding plates arranged at intervals in the vehicle traveling direction.

In this case, since the shielding plate shields the upstream side of each row, for example, compared to the case where all the light emitting elements are surrounded by one shielding member made of a cylindrical member (see FIG. 7), the incident light is directed to the upstream side. The effect of suppressing diffusion can be further improved.
In addition, since the upstream side of the row composed of a plurality of light emitting elements can be shielded by a single shielding plate, the number of parts of the shielding member compared to the case where a “shielding piece” described later that individually shields each light emitting element is employed. The manufacturing cost can be reduced.

  (3) However, when the vehicle sensing light emitting member has a plurality of light emitting elements arranged in a predetermined pattern, the shielding member is arranged to shield the upstream side of the light emitting element. You may comprise by several shielding small pieces.

In this case, since the shielding pieces respectively shield the upstream side of the light emitting element, for example, compared to the case where all the light emitting elements are surrounded by one shielding member made of a cylindrical member (see FIG. 7), the incident light is on the upstream side. This can further improve the diffusion suppressing effect.
Further, if such a shielding piece is employed, the number of parts of the shielding member is increased as compared with the case of the shielding plate, but there is an advantage that the upstream side of the light emitting element can be reliably shielded regardless of the arrangement pattern of the light emitting elements. .

(4) In the optical beacon of the present invention, when the vehicle-sensing light-emitting member is housed in a housing having a transmission window portion for the incident light, all or a part of the shielding member is the housing. It is preferable to be stored in the body.
If it does in this way, the enlargement of the height dimension of the beacon head (projector / receiver) accompanying provision of the shielding member can be suppressed as much as possible, which contributes to the compactness of the beacon head. Moreover, since the shielding member is not exposed to the outside of the housing or the exposure thereof is reduced, the aesthetic appearance of the beacon head is also improved.

(5) When all or part of the shielding member is housed in the housing, the light emitting point of the light sensing member for vehicle detection is disposed in the vicinity of the upper edge of the shielding member in the housing. Is preferred.
In this way, compared to the case where the light emitting point is arranged at a position lower than the upper end edge of the shielding member (for example, the central portion in the vertical direction of the shielding member), the incident light is more diffused upstream. It can suppress reliably and the shielding effect of the incident light by a shielding member improves.

(6) In the optical beacon of the present invention, it is preferable that the color of at least the surface on which the incident light is directly generated in the shielding member is black.
The reason is that if the surface on which the incident light is directly irradiated is black, the reflection of the incident light on the shielding member can be suppressed, and the diffusion of the incident light to the upstream side can be more effectively suppressed. .

  (7) The optical beacon of the present invention viewed from another viewpoint is an optical beacon that has both an optical communication function and a vehicle sensing function, and a light emitting member for optical communication that transmits downlink light toward a road, A vehicle-sensing light-emitting member for sending vehicle-sensing incident light downstream of a downlink region where the in-vehicle device can receive the downlink light, and a vehicle-sensing light-emitting member inside are housed. A housing having a transmissive window portion for incident light, and the vehicle-sensing light emitting member is disposed away from the transmissive window portion by a height dimension capable of suppressing diffusion of the incident light upstream. It is characterized by being.

According to the optical beacon of the present invention, since the light emitting member for vehicle detection is arranged away from the transmission window portion by a height dimension that can prevent the incident light from diffusing upstream, the downstream side of the downlink region. It is possible to prevent or reduce the incident light from interfering with the downlink light in the portion closer to the side.
For this reason, in road-to-vehicle communication using an optical beacon that has both an optical communication function and a vehicle sensing function, it is suppressed that the downstream communication is inhibited by the incident light for vehicle detection, and the downward communication is further improved. It can be done reliably.

  (8) An optical beacon of the present invention viewed from another viewpoint is an optical beacon having both an optical communication function and a vehicle sensing function, and a light emitting member for optical communication that transmits downlink light toward a road, A vehicle-sensing light-emitting member for sending vehicle-sensing incident light downstream of a downlink region where the in-vehicle device can receive the downlink light, and a vehicle-sensing light-emitting member inside are housed. A housing having a transmission window portion for incident light, wherein the light emitting member for vehicle detection is upstream of the transmission window portion by a horizontal dimension capable of suppressing diffusion of the incident light to the upstream side. It is characterized by being shifted to

According to the optical beacon of the present invention, since the light emitting member for vehicle detection is arranged to be shifted to the upstream side with respect to the transmission window portion by a horizontal dimension capable of suppressing the diffusion of incident light to the upstream side, In the portion from the downstream side of the link region, the phenomenon that the downlink light interferes with the incident light can be prevented or reduced.
For this reason, in road-to-vehicle communication using an optical beacon that has both an optical communication function and a vehicle sensing function, it is suppressed that the downstream communication is inhibited by the incident light for vehicle detection, and the downward communication is further improved. It can be done reliably.

(9) In the optical beacon of the present invention, the vehicle-sensing light emitting member includes one or more light emitting elements (for example, LEDs) as components.
In this case, in order to suppress the diffusion of incident light from the light emitting element to the upstream side, it is desirable that the directivity angle of the light emitting element is as small as possible. For example, a light emitting element having a directivity angle of 7 degrees or less is employed. It is preferable.

  (10) The optical beacon of the present invention viewed from another viewpoint is an optical beacon that has both an optical communication function and a vehicle sensing function, and a light emitting member for optical communication that transmits downlink light toward a road, A vehicle sensing light emitting member for transmitting vehicle sensing incident light downstream of a downlink region where the in-vehicle device can receive the downlink light, and the incident light whose light emission timing is synchronized with the pulse of the downlink light. And a light emission control unit for sending the light to the vehicle sensing light emitting member.

According to the optical beacon of the present invention, the light emission control unit sends the incident light whose light emission timing is synchronized with the downlink light pulse to the vehicle sensing light emitting member. Becomes an optical signal similar to the downlink light.
For this reason, in road-to-vehicle communication using an optical beacon that has both an optical communication function and a vehicle sensing function, the downstream communication is not hindered by the incident light for vehicle sensing, and the downstream communication is more reliable. Can be done.

(11) In road-to-vehicle communication using an optical beacon, periodic light emission of downlink light is performed permanently so that the in-vehicle device can detect that it has entered the communication area of the optical beacon. Therefore, if the duration in which the light emission timing is synchronized with the pulse of the downlink light and the duration of the transmission of the incident light is simply matched with the downlink light, the periodic light emission of the incident light is also performed permanently.
However, in this case, it is necessary for the light-emitting member for vehicle detection to clear substantially the same durability and heat resistance as the light-emitting member for optical communication, which causes a rise in manufacturing cost.

Therefore, in the optical beacon of the present invention, the light emission control unit has a continuation period in which the transmission of the incident light is continued and an interruption period in which the transmission of the incident light is stopped with respect to a pulse period of the downlink light. It is preferable to perform pause control that is repeated at a long predetermined period.
In this case, since the light emission control unit performs the pause control including the interruption period, the durability and heat resistance necessary for the light emitting member for vehicle detection are compared with those required for the light emitting member for optical communication. It can be set to a lower value, and the rise in production costs can be suppressed.

(12) As described above, when the incident light transmitted by the light emitting member for vehicle detection is emitted at a timing synchronized with the downlink light transmitted by the light emitting member for optical communication, the incident light for vehicle detection is downlinked. The pulse signal has the same cycle as that of light, and interference from the viewpoint of the pulse cycle does not occur.
However, in this case, in the overlapping area where both the downlink light and the incident light reach the in-vehicle device, the reception intensity in the downlink direction in the in-vehicle device increases rapidly, and the amplification circuit of the optical receiving unit is saturated, and the downlink There is a possibility that light cannot be received properly.

Therefore, the light emission control unit may cause the incident light to be transmitted so that the plurality of pulses of the incident light at the head portion of the duration period converge to the maximum light amount over a predetermined rise time. preferable.
In this way, it is possible to prevent an abrupt increase in light intensity in the overlapping area, and it is possible to increase the possibility that the in-vehicle device appropriately receives the downlink signal.

(13) For the same reason, the light emission control unit transmits the incident light so that the plurality of pulses of the incident light at the end portion of the duration period converge to zero over a predetermined time required for falling. It is preferable to do so.
In this way, it is possible to prevent a rapid decrease in light intensity in the overlapping area, and the in-vehicle device can appropriately receive the downlink signal.
For the same reason, the light emission control unit may send the incident light so that the light amount of the incident light increases more slowly than the light amount of the downlink light, or the light emission control. The unit may cause the incident light to be transmitted so that the amount of the incident light gradually decreases from the amount of the downlink light.
Furthermore, for the same reason, the light emission control unit may cause the incident light to be transmitted so that the increase degree of the light amount of the incident light is suppressed compared to the increase degree of the light amount of the downlink light. The incident light may be transmitted such that the degree of decrease in the amount of incident light is suppressed as compared to the degree of decrease in the amount of downlink light.

  (14) The present invention viewed from another viewpoint is an in-vehicle device that performs optical communication with an optical beacon having both an optical communication function and a vehicle sensing function, and an optical transmission unit that transmits uplink light to the optical beacon; An optical receiver having a filter function for receiving downlink light transmitted by the optical beacon and not receiving an optical signal having a predetermined frequency or lower.

According to the vehicle-mounted device of the present invention, since the optical receiver having the filter function that receives the downlink light transmitted by the optical beacon and does not receive the optical signal of the predetermined frequency or less is provided, the downstream side of the downlink region In the further portion, even if the incident light interferes with the downlink light, only the downlink light can be received.
For this reason, in road-to-vehicle communication using an optical beacon that has both an optical communication function and a vehicle sensing function, it is suppressed that the downstream communication is inhibited by the incident light for vehicle detection, and the downward communication is further improved. It can be done reliably.

(15) In the in-vehicle device of the present invention, the filter function of the optical receiver can be implemented by various filter circuits. For example, it is preferable to employ an RC configuration filter circuit in which a resistor and a capacitor are combined.
The reason is that a filter circuit having an RC configuration can be mounted more easily than other filter circuits using an operational amplifier or the like, and can reduce the effort required to change the design of the in-vehicle device.

  (16) A road-to-vehicle communication system according to the present invention includes a vehicle-mounted device according to the above (12) or (13) and the optical beacon (an optical beacon having both an optical communication function and a vehicle sensing function). In the inter-vehicle communication system, the optical beacon includes a vehicle sensing light emitting member that emits incident light for vehicle sensing so that a duty ratio of a light emission period is approximately 50%. To do.

According to the road-to-vehicle communication system of the present invention, the light-emitting member for detecting the vehicle of the optical beacon emits the incident light for vehicle detection so that the duty ratio of the light emission period is approximately 50%. It is possible to most effectively suppress the generation of harmonic component noise.
For this reason, the filter function below a predetermined frequency on the in-vehicle device side works more effectively, and downlink light can be received more reliably.

  As described above, according to the present invention, in the road-to-vehicle communication using the optical beacon having both the optical communication function and the vehicle sensing function, it is possible to perform the communication in the down direction more reliably.

It is a block diagram which shows the whole structure of a road-vehicle communication system. It is the top view of the road which looked at the installation part of an optical beacon from the top. It is a side view of the road which shows the communication area | region and incident area of an optical beacon. It is a functional block diagram which shows an example of the circuit structure of an optical beacon. (A) is a perspective view at the time of seeing the beacon head of an installation state from diagonally downward, (b) is a side view of the beacon head of an installation state. It is a perspective view which shows the internal structure of a beacon head. (A) And (b) is typical sectional side view of the beacon head concerning 1st Embodiment. (A) is typical sectional drawing of the beacon head which concerns on the modification 1 of 1st Embodiment, (b) And (c) is a top view at the time of seeing the light emitting member for vehicle detection from the downward direction. is there. (A)-(c) is a top view at the time of seeing the transmission window part of a case from the lower part in the beacon head concerning modification 2 of a 1st embodiment. (A) And (b) is a typical side sectional view of a beacon head concerning modification 3 of a 1st embodiment. It is a functional block diagram which shows an example of the circuit structure of the optical receiver in the vehicle equipment which concerns on 3rd Embodiment. It is a circuit block diagram which shows the example of the light emission circuit in the case of taking the synchronization of a pulse. 13 is a time chart of each output signal in the light emitting circuit of FIG. 12. It is a circuit block diagram which shows an example of the additional circuit with respect to the light emission circuit of FIG. It is a time chart of each output signal in the additional circuit of FIG.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[Overall system configuration]
FIG. 1 is a block diagram showing an overall configuration of a road-vehicle communication system according to an embodiment of the present invention. FIG. 2 is a plan view of the road R when the installation portion of the optical beacon 4 of this embodiment is viewed from above.
As shown in FIG. 1, the road-to-vehicle communication system of this embodiment includes an infrastructure-side traffic control system 1 and an in-vehicle device 2 mounted on a vehicle 20 (see FIG. 3) traveling on a road R. .

The traffic control system 1 includes a central device 3 provided in a traffic control room and the like, and a large number of optical beacons (optical vehicle detectors) 4 installed in various places on the road R. The optical beacon 4 transmits near infrared rays. Wireless communication can be performed with the in-vehicle device 2 by optical communication as a communication medium.
The optical beacon 4 includes a beacon controller 7 that performs communication control and the like, and a plurality of (four in the example of FIG. 1) beacon heads (projector / receiver) 8 connected to the sensor interface of the beacon controller 7. have.

The beacon controller 7 is connected to a communication unit 6 on the infrastructure side, and the communication unit 6 is connected to the central apparatus 3 by a communication line 5 such as a telephone line.
The communication unit 6 can be configured by, for example, a traffic signal controller that controls the color of a signal lamp, an information relay device that performs a relay process of traffic information on the infrastructure side, and the like.

The optical beacon 4 of this embodiment employs a full-duplex communication method. That is, the beacon controller 7 described later simultaneously performs transmission control in the downlink direction for the light emitting unit 13 for optical communication and reception control in the uplink direction for the light receiving unit 14 for communication.
On the other hand, the in-vehicle device 2 of the present embodiment employs a half-duplex communication method. That is, the below-described vehicle-mounted controller 21 does not simultaneously perform uplink direction transmission control for the optical transmission unit 23 and downlink direction reception control for the optical reception unit 24.

[Overall configuration of optical beacon]
The beacon head 8 of the optical beacon 4 includes a transmission / reception unit 11 for optical communication and a sensor unit 12 for vehicle detection inside a housing 31 (see FIG. 3).
As described above, in the present embodiment, by combining the units 11 and 12 for optical communication and vehicle detection in the casing 31 of one beacon head 8, the light having both the optical communication function and the vehicle detection function, respectively. A beacon 4 is configured.

The transmission / reception unit 11 is an optical transceiver that transmits and receives optical signals to and from the in-vehicle device 2 wirelessly.
As shown in FIG. 1, the transmission / reception unit 11 includes a light-emitting unit 13 for optical communication that transmits downlink light DO, and a light-receiving unit 14 for optical communication that receives uplink light UO and converts it into an electrical signal. Have.

A light emitting unit 13 for optical communication (hereinafter also referred to as “communication light emitting unit 13”) includes a transmission circuit that converts a downstream frame transmitted from the beacon controller 7 into a serial transmission signal having a predetermined transmission rate; A light emitting element made of a light emitting diode (LED) that converts the output transmission signal into an optical signal in a downlink direction.
The light emitting element of the communication light emitting unit 13 sends the downlink light DO (see FIG. 3), which is a near infrared light signal, obliquely downward toward the upstream side.

The light receiving unit 14 for optical communication (hereinafter also referred to as “communication light receiving unit 14”) amplifies a light receiving element such as a photodiode (PD) and an electric signal output from the light receiving element. And a receiving circuit for generating a digital signal.
The light receiving element of the communication light receiving unit 14 receives the uplink light UO (see FIG. 3) which is a near-infrared light signal transmitted from the vehicle-mounted device 2, and the receiving circuit of the communication light receiving unit 14 receives the received uplink. The optical UO is converted into an electric signal and sent to the beacon controller 7.

The sensor unit 12 is a light detection sensor for detecting the presence of the vehicle 20 passing almost directly below the beacon head 8 without contact.
As shown in FIG. 1, the sensor unit 12 includes a vehicle sensing light emitting unit 15 that transmits incident light IO, and a vehicle sensing light receiving unit 16 that receives reflected light RO and converts it into an electrical signal.

The vehicle-sensing light-emitting unit 15 (hereinafter also referred to as “sensing light-emitting unit 15”) transmits incident light IO (see FIG. 3), which is a light pulse signal having a predetermined period, downward.
The vehicle sensing light receiving unit 16 (hereinafter also referred to as the “sensing sensing light receiving unit 16”) receives and receives the reflected light RO (see FIG. 3) of the incident light IO on the road R and the vehicle 20. The reflected light RO is converted into an electric signal and sent to the beacon controller 7.

The beacon controller 7 includes a computer device having a signal processing unit, a CPU, a memory, and the like, and has a function as a communication control unit that performs communication with the central device 3 and communication between the in-vehicle device 2 and the vehicle according to a predetermined communication interface standard. And a function as a sensing control unit of the vehicle 20.
The beacon controller 7 stores a computer program for communication control and sensing control in a storage device, and the CPU reads out and executes the program so that the CPU controls the communication control unit and the sensing control unit. Function as.

For example, the beacon controller 7 transmits a downlink signal including lane communication information without a vehicle ID to the communication light emitting unit 13 at a predetermined period, and the vehicle that the in-vehicle device 2 transmits when receiving the downlink signal is triggered. Wait for the uplink signal containing the ID.
When the beacon controller 7 receives the uplink signal at the communication light receiving unit 14, the beacon controller 7 includes another lane notification information storing the vehicle ID extracted from the uplink signal and provision information for the vehicle ID. The downlink signal is generated to switch the downlink, and the generated downlink signal is transmitted to the communication light emitting unit 13 at a predetermined cycle.

In addition, if information useful for traffic signal control such as probe data is included in the uplink signal, the beacon controller 7 transfers the information to the central device 3.
Further, the beacon controller 7 transmits the incident light IO having a predetermined wavelength to the sensing light emitting unit 15 at a constant intensity and a pulse period, and whether the received light intensity of the reflected light RO received by the sensing light receiving unit 16 is equal to or greater than a threshold value. Thus, the presence of the vehicle 20 is detected. This threshold value is not limited to a fixed value, and may vary depending on, for example, a follow-up process according to the received light intensity of the reflected light RO.

That is, the beacon controller 7 generates a sensing signal of the vehicle 20 and transmits the sensing signal to the central device 3 when the light receiving intensity of the reflected light RO that is equal to or greater than the threshold value is detected in the sensing light receiving unit 16.
The wavelength of the incident light IO transmitted from the sensing light emitting unit 15 is the same as the wavelength of the downlink light DO transmitted from the communication light emitting unit 13 or close enough to cause interference with the downlink light DO. It is assumed that the wavelength is the same (for example, 850 nm).

[Optical beacon installation status]
As shown in FIG. 2, the optical beacon 4 of the present embodiment is installed on a road R having a plurality (four in the illustrated example) of lanes R1 to R4 in the same direction.
The optical beacon 4 includes a plurality of the beacon heads 8 provided respectively corresponding to the lanes R1 to R4, and one beacon controller 7 which is a control unit that collectively controls the beacon heads 8. ing.

The beacon controller 7 is installed on a support column 17 standing on the side of the road. Each beacon head 8 is attached to an erection bar (beam member) 18 that is horizontally installed from the support column 17 to the road R side, and is disposed immediately above each lane R1 to R4 of the road R.
The communication light emitting unit 13 of each beacon head 8 emits the downlink light DO toward the upstream side in the vehicle traveling direction from directly below the own device, and thereby, road-to-vehicle communication with the in-vehicle device 2. The communication area A for performing the above is set on the upstream side of the beacon head 8.

  Further, the sensing light emitting unit 15 of each beacon head 8 emits the incident light IO directly below the own aircraft, and thereby the sensing area of the vehicle 20 that passes through the predetermined lanes R1 to R4 of the road R. The incident region B is set almost directly below the beacon head 8.

[Communication area and incident area of optical beacons]
FIG. 3 is a side view of the road R showing the communication area A and the incident area B of the optical beacon 4.
As shown in FIG. 3, the communication area A of the transmission / reception unit 11 includes a downlink area DA (solid hatched portion) that is a receivable range of the downlink light DO by the in-vehicle device 2 and an uplink light UO by the beacon head 8. And an uplink area UA (dashed hatched portion), which is a light receiving range.

According to the “near-infrared interface standard” of an optical beacon (optical vehicle sensor), the upstream ends c0 of both areas DA and UA coincide with each other.
Further, the standard values (in the case of ordinary roads) of the upstream and downstream end positions of the areas DA and UA in the above standard are exemplified as follows. However, this standard value is a value when the height H from the road surface is 1.0 m and the upstream direction from the position immediately below the light emitter / receiver 8 (origin O) is a positive number.

Downstream area DA downstream end position a0: +1.3 m
Downstream end position b0 of the uplink area UA: a0 + 2.1 m (= 3.4 m)
Upstream end position c0 of both areas DA and UA: b0 + 1.6 m (= 5.0 m)

The incident area B of the sensor unit 12 is an irradiation range of the incident light IO on which the sensing light emitting unit 15 enters the road R.
Here, if the light emission direction V1 of the incident light IO is set strictly below (downward in the vertical direction), the intensity of the reflected light RO from the road surface increases, for example, when a puddle is formed on the road surface during rain, and an error occurs. There is a high possibility that detection will increase and proper vehicle sensing will not be possible. Therefore, normally, the emission direction V1 of the incident light IO is directed to the upstream side (plus side) by a predetermined angle α (for example, 4.5 °) with respect to the vertical direction.

The set values of the upstream and downstream end positions x0, y0 of the incident area B at the road surface height H = 1.0 m when the light emission direction V1 is oriented as described above are as follows.
Downstream end position x0 of incident area B: -0.15 m
Upstream end position y0 of incident area B: +0.93 m

The light emission direction V1 of the incident light IO may be directed downstream (minus side) by a predetermined angle (for example, 4.5 °) with respect to the vertical direction, contrary to the above.
In this way, it is possible to further reduce the interference of the incident light IO with the downlink light DO, compared to the case where the light emission direction V1 is directed upstream with respect to the vertical direction.
Further, if the light emitting direction V1 is directed downstream, the downstream end position a0 of the downlink area DA can be set further downstream, and the length of the downlink area DA in the vehicle traveling direction can be extended. For this reason, there is an advantage that the downlink communication capacity can be expanded in the optical beacon 4 having both the optical communication function and the vehicle sensing function.

[Configuration of in-vehicle device]
As shown in FIG. 3, the in-vehicle device 2 of this embodiment includes an in-vehicle controller 21 and an in-vehicle head 22. An optical transmitter 23 and an optical receiver 24 are accommodated in the in-vehicle head 22.
Among these, the optical transmission unit 23 has a light emitting element that emits uplink light UO (uplink direction optical signal) made of near infrared rays, and the optical reception unit 24 is a near infrared ray transmitted to the downlink area DA. And a light receiving element that receives downlink light UO (an optical signal in the downlink direction).

The optical transmission unit 23 is a light emitting circuit that converts an upstream frame output from the in-vehicle controller 21 into a serial transmission signal having a predetermined transmission rate, and converts the output transmission signal into an optical signal in the uplink direction. And a light emitting element made of a diode or the like.
According to the current standard, the transmission speed of the uplink optical UO transmitted by the optical transmission unit 23 of the in-vehicle device 2 is 64 kbps.

The light receiving unit 24 includes a light receiving element such as a photodiode and a receiving circuit that amplifies an electric signal output from the light receiving element and generates a digital reception signal.
According to the current standard, the transmission speed of the downlink optical DO received by the optical receiver 24 is 1024 kbps.

The in-vehicle controller 21 includes a computer device having a signal processing unit, a CPU, a memory, and the like, and has a function as a communication control unit that performs road-vehicle communication with the optical beacon 4.
The in-vehicle controller 21 stores a computer program for communication control in a storage device, and the CPU functions as the communication control unit when the CPU reads and executes the program.

Furthermore, the in-vehicle controller 21 generates traveling data of the host vehicle (for example, probe information that is traveling locus data in which passing positions and passing times are arranged in time series) as uplink data, and the optical transmission unit 23. It also has a function of transmitting to the uplink.
In this case, for example, if the uplink speed is increased, more probe information (such as a longer road section that records the travel locus, or a higher recording density of the passage position and passage time in the same road section) Information) can be transmitted.

In addition, the vehicle-mounted controller 21 of this embodiment may have a circuit configuration in which a simple control unit including an ASIC (Application Specific Integrated Circuit) is provided separately from the main body control unit including the CPU.
For example, when the optical receiving unit 24 receives any downlink frame, the simple control unit includes only one uplink frame (conventional uplink frame having a transmission rate of 64 kbps) including the vehicle ID of the host vehicle, and the optical transmission unit 23. Has the function of transmitting to the uplink.

[Circuit configuration of optical beacon]
FIG. 4 is a functional block diagram showing an example of the circuit configuration of the optical beacon 4.
As shown in FIG. 4, the beacon head 8 includes a light emitting unit 13 and a light receiving unit 14 for optical communication, and a light emitting unit 15 and a light receiving unit 16 for vehicle detection.
The beacon controller 7 includes a communication IC 69 for communication control, a sensing processing unit 71 for sensing control, and a main CPU 70 and a sensing CPU 72 that perform digital signal processing.

The light emitting unit 13 for optical communication includes a light emitting member 42 for optical communication and a drive circuit 61, and the light receiving unit 14 for optical communication includes a light receiving member 43 for optical communication, an amplifier 62, a filter circuit 63, and a comparator 64. Including.
The communication IC 69 converts the downlink data acquired from the main CPU 70 by a predetermined encoding method (for example, Manchester code), generates a pulse signal P1 including a serial electric signal having a predetermined period, and generates the pulse signal P1. Output to the drive circuit 61.

  The drive circuit 61 includes a switching element that generates a drive voltage of the light emitting element based on the pulse signal P1 input from the communication IC 69, and outputs the generated drive voltage to the light emitting member 42 to drive the light emitting element.

The amplifier 62 amplifies the electrical signal photoelectrically converted by the light receiving element of the light receiving member 43, and outputs the amplified electrical signal to the filter circuit 63. The filter circuit 63 extracts a high-speed signal component having at least a transmission rate in the uplink direction (64 kbps in this embodiment), and outputs the extracted high-speed signal to the comparator 64.
The comparator 64 compares the input high-speed signal with a threshold value, and outputs a digital reception signal (bit data) extracted by this comparison to the communication IC 69.

  The communication IC 69 determines the transmission speed of the received signal using the first 5-byte idle pattern and generates a reception clock, samples the bit data with the generated clock, and reproduces the upstream data included in the upstream frame. Then, the communication IC 69 sends the reproduced uplink data to the main CPU 70.

The vehicle sensing light emitting unit 15 includes a vehicle sensing light emitting member 45 and a drive circuit 65, and the vehicle sensing light receiving unit 16 includes a vehicle sensing light receiving member 46, an amplifier 66, a filter circuit 67, and a peak hold circuit. 68.
The sensing processing unit 71 autonomously generates a pulse signal P2 having a predetermined period and outputs the pulse signal P2 to the drive circuit 65.

The driving circuit 65 includes a switching element that generates a driving voltage for the light emitting element based on the pulse signal P2 input from the sensing processing unit 71, and outputs the generated driving voltage to the light emitting member 45 to drive the light emitting element. To do.
The amplifier 66 amplifies the electric signal photoelectrically converted by the light receiving element of the light receiving member 46 and outputs the amplified electric signal to the filter circuit 67. The filter circuit 63 extracts a signal having at least the same frequency component as the incident light IO and outputs the extracted signal to the peak hold circuit 68.

The peak hold circuit 68 detects the envelope of the input electric signal and outputs the detection signal to the sensing processing unit 71.
The sensing processing unit 71 determines whether or not the input detection signal is equal to or greater than a predetermined threshold, and outputs a pulse signal during a period when the detection signal is equal to or greater than the threshold to the sensing CPU 72 as sensing data. Then, the sensing CPU 72 outputs the sensing data acquired from the sensing processing unit 71 to the main CPU 70.

[Beacon head exterior configuration]
FIG. 5 shows an external configuration in the installed state of the beacon head 8. 5A is a perspective view when the beacon head 8 in the installed state is viewed obliquely from below, and FIG. 5B is a side view of the beacon head 8 in the installed state.

  As shown in FIG. 5, the beacon head 8 includes a casing 31 having an inclined surface 36 formed at the bottom, and a gate-shaped bracket 32 that supports the left and right side surfaces of the casing 31. The central portion of the bracket 32 in the left-right direction is fixed to the beam member 18 via a clamp 33, whereby the casing 31 is attached in a suspended state below the beam member 18.

The housing 31 includes a casing 34 having a substantially rectangular shape when viewed from above and a ceiling plate 35 joined to a flange portion of the upper opening of the casing 34.
A first bottom surface portion 36 located on the upstream side and a second bottom surface portion 37 located on the downstream side are formed at the bottom of the casing 34. The first bottom surface portion 36 is an inclined surface inclined upward from the upstream edge of the second bottom surface portion 37 toward the upstream side, and the second bottom surface portion 37 is set almost horizontally in the installed state of FIG. Has been.

On the first bottom surface portion 36, a pair of left and right rectangular transmission window portions 36L, 36R are juxtaposed in the left-right direction at intervals.
These transmission window portions 36L and 36R conform to a predetermined wavelength (a “near infrared interface standard” for optical beacons) in which a pair of left and right openings formed in the first bottom surface portion 36 is used for optical communication with the vehicle-mounted device 2. It is configured by closing with a light transmitting sheet that mainly transmits light in the wavelength band.

Of the two transmission window portions 36L and 36R, the left window portion 36L is a light receiving window for the uplink light UO and corresponds to the light receiving member 43 (see FIG. 6) for optical communication. Accordingly, the uplink light UO transmitted from the in-vehicle device 2 passes through the left window portion 36L and reaches the light receiving member 43.
On the other hand, the right window portion 36R is a light projection window for the downlink light DO and corresponds to the light emitting member 42 (see FIG. 6) for optical communication. Accordingly, the downlink light DO sent out by the light emitting member 42 is transmitted to the outside of the housing 31 through the right window 36R.

Also on the second bottom surface portion 37, a pair of left and right rectangular transmission window portions 37L and 37R are arranged in parallel in the left-right direction with a space therebetween.
These transmission window portions 37L and 37R are configured by closing a pair of left and right openings formed in the second bottom surface portion 37 with a light transmission sheet that mainly transmits light of a predetermined wavelength used for vehicle sensing.

Of the two transmission window portions 37L and 37R, the left window portion 37L is a projection window for incident light IO, and corresponds to the light-emitting member 45 (see FIG. 6) for on-vehicle sensing. Therefore, the incident light IO transmitted by the light emitting member 45 is irradiated outside the housing 31 through the left window 37L.
On the other hand, the right window portion 37R is a light receiving window for the reflected light RO and corresponds to the light receiving member 46 for vehicle detection (see FIG. 6). Accordingly, the reflected light RO of the incident light IO reflected by the road R or the vehicle 20 passes through the right window 37R and reaches the light receiving member 46.

[Internal configuration of beacon head]
FIG. 6 is a perspective view showing the internal structure of the beacon head 8.
Specifically, FIG. 6 is a perspective view showing the internal structure when the casing 31 shown in FIG. 5A is turned upside down and the casing 34 is removed from the casing 31 in the inverted state.
As is clear from a comparison between FIG. 5A and FIG. 6, the definition of the directions of the upstream / downstream side and the left / right side in FIG. 6 follows the case of the installation state shown in FIG. .

As shown in FIG. 6, the transmission / reception unit 11 includes a flat circuit board 41, a light-emitting member 42 for optical communication arranged on the right side of the circuit board 41, and light arranged on the left side of the circuit board 41. And a light receiving member 43 for communication.
The light-emitting member 42 for optical communication includes a large number of light-emitting elements 42A made of, for example, LEDs, and is configured by arranging these light-emitting elements 42A vertically and horizontally in a predetermined range on the right side portion of the circuit board 41.

The light receiving member 43 for optical communication includes a light receiving element 43A made of, for example, PD attached to the left side portion of the circuit board 41, and a lens 43B that condenses the uplink light UO on the light receiving surface of the light receiving element 43A. ing.
Similarly to the first bottom surface portion 36 of the casing 34, the circuit board 41 of the transmission / reception unit 11 is inclined so as to be higher on the upstream side in the installed state.

When the casing 31 is assembled by joining the flange portion of the casing 34 to the outer peripheral edge portion of the ceiling plate 35 shown in FIG. 6, all the light emitting elements 42 </ b> A constituting the light emitting member 42 for optical communication are The right side window portion 36R (see FIG. 5) of the 36 is disposed in the vicinity of the light transmission sheet so as to be within the frame of the right side window portion 36R.
Further, in this case, the lens 43B of the light receiving member 43 for optical communication is close to the light transmission sheet of the left window portion 36L (see FIG. 2) of the first bottom surface portion 36, and fits within the frame of the left window portion 36L. Placed in.

On the other hand, the sensor unit 12 includes a pair of left and right flat circuit boards 44L and 44R, a vehicle sensing light emitting member 45 provided on the left circuit board 44L, and a vehicle sensing light provided on the right circuit board 44R. Light receiving member 46.
The vehicle-sensing light-emitting member 45 includes a large number of light-emitting elements 45A made of LEDs, for example, and is configured by arranging these light-emitting elements 45A vertically and horizontally within a predetermined range of the circuit board 44L.

More specifically, the vehicle-sensing light emitting member 45 is arranged with respect to the circuit board 44L in columns in the vehicle traveling direction (upstream / downstream direction in FIG. 6) and in the road width direction (left side / right side in FIG. 6). The light emitting elements 45A are two-dimensionally arranged in a row in the (direction) direction.
In the example of FIG. 6, a total of 20 light emitting elements 45A are arranged in 4 columns × 5 rows. However, the arrangement pattern of the light emitting elements 45A is not limited to this. The light emitting elements 45A may be arranged in a so-called zigzag pattern (see FIG. 8C).

The vehicle sensing light receiving member 46 includes a light receiving element 46A made of, for example, PD attached to the circuit board 44R, and a lens 46B that collects the reflected light RO on the light receiving surface of the light receiving element 46A.
In the example of FIG. 6, the circuit boards 44L and 44R of the sensor unit 12 are separated for light emission and light reception, but the light emitting member 45 and the light receiving member 46 are integrally formed without separating the boards according to their uses. It may be mounted on the circuit board.

When the casing 31 is assembled by joining the flange portion of the casing 34 to the outer peripheral edge portion of the ceiling plate 35 shown in FIG. 6, all the light emitting elements 45 </ b> A constituting the light emitting member 45 for vehicle detection become the second bottom surface portion. The left side window portion 37L of 37 (see FIG. 5) is positioned almost directly above the light-transmitting sheet and is disposed so as to fit within the frame of the left side window portion 37L.
Further, in this case, the lens 46B of the light receiving member 46 for vehicle detection is close to the right window portion 37R (see FIG. 5) of the second bottom surface portion 37 almost directly above the light transmitting sheet, and is within the frame of the right window portion 37R. It is arranged to fit in.

5 and 6, “V1” indicates the “light emitting direction” of the incident light IO by the light emitting member 45, and “V2” indicates the “light receiving direction” of the reflected light RO by the light receiving member 46.
Here, the “light emission direction V1” refers to the optical axis direction of the incident light IO transmitted from one light source when a plurality of light emitting elements 45A arranged vertically and horizontally are regarded as one light source. . Accordingly, the light emission direction V1 substantially coincides with the direction of the center line that vertically passes through the circuit board 44L through the center of the installation range of the light emitting member 45.

On the other hand, the “light receiving direction V2” refers to a direction in which the light receiving level with respect to the light receiving element 46A by the reflected light RO having the same intensity is the highest. Here, in the present embodiment, the light receiving element 46A and the lens 46B are arranged coaxially, and are attached so that the light receiving surface of the light receiving element 46A is parallel to the circuit board 44R.
Therefore, the light receiving direction V2 substantially coincides with the direction of the center line passing through the center of the light receiving element 46A and vertically passing through the circuit board 44R, and is substantially parallel to the light emitting direction V1.

In addition, although the cylindrical member of the code | symbol 51 shown with a virtual line in FIG. 6 has shown an example of the "shielding member" at the time of accommodating in the housing | casing 31, this is mentioned later.
In addition, the internal structure of the beacon head 8 illustrated in FIG. 6 employs a structure in which the installation positions of the light emitting members 42 and 45 and the light receiving members 43 and 46 are reversed left and right between the transmission / reception unit 11 and the sensor unit 12. However, they may be aligned in the left-right direction.

[Problems of optical beacons with vehicle sensing function]
As described above, the standard value of the downstream end position a0 of the downlink area DA is +1.3 m, and the normal set value of the upstream end position y0 of the incident area B is +0.93 m. Therefore, if the beacon head 8 is appropriately set in compliance with these values, geometrically, the incident light IO does not interfere with the downlink light DA (see FIG. 3).

However, the incident light IO sent from the vehicle-sensing light emitting member 45 from the downstream side of the downlink area DA is caused by an error in the directivity direction or directivity angle inherent in the light emitting element 45A, irregular reflection of the incident light IO, or the like. There is a risk of reaching the part and interfering with the downlink light DO.
In particular, when the downstream end position a0 of the downlink area DA is set downstream from the standard value in order to increase the certainty of reception of the downlink light DO by the in-vehicle device 2, the incident light IO is down. The possibility of interference with the link light DA is further increased.

[First Embodiment]
Therefore, in the first embodiment, the upstream side of the vehicle-sensing light emitting member 45 is optically shielded to suppress the diffusion of the incident light IO to the upstream side as much as possible, thereby solving the above-described problems. .

FIGS. 7A and 7B are schematic side cross-sectional views of the beacon head 8 according to the first embodiment. Specifically, the beacon head is focused on the light-emitting member 45 for vehicle detection. FIG.
In the example of FIG. 7A, a shielding member 51 for narrowing the irradiation range of the light emitting member 45 for vehicle detection is provided inside the housing 31. The shielding member 51 is made of an opaque cylindrical member 52 made of metal or synthetic resin.

In addition, it is desirable that the color of the cylindrical member 52 is black with no gloss from the viewpoint of suppressing reflection of infrared rays. However, since the incident light IO is strongly reflected from the inner surface of the cylindrical member 52 directly irradiated with the incident light IO from the light emitting element 45A, an arbitrary color is adopted for the outer surface of the cylindrical member 52 where the direct irradiation does not occur. Can do.
The same applies to the color of the shielding member 51 in the case of other shielding members 51 such as a shielding plate 53 and a shielding piece 53 described later.

The cylindrical member 52 of the present embodiment is formed of a prismatic body having a hollow cross section, which has a rectangular cross section substantially the same as the planar shape of the transmission window portion 37L.
The cylindrical member 52 is erected on the upper surface of the bottom portion of the housing 31 (the inner surface of the second bottom surface portion 37 in FIG. 5) by fixing the lower end edge to the periphery of the transmission window portion 37L. A circuit board 44L on which a vehicle sensing light emitting member 46 is mounted is attached to the upper end portion of the cylindrical member 52.

According to the optical beacon 4 of the first embodiment, the shielding member 51 formed of the cylindrical member 52 shields the upstream side of the vehicle sensing light emitting member 45 and suppresses the diffusion of the incident light IO to the upstream side. Accordingly, it is possible to prevent or reduce the incident light IO from interfering with the downlink light DO in the portion from the downstream side of the downlink area DA.
For this reason, in road-to-vehicle communication using the optical beacon 4 having both the optical communication function and the vehicle sensing function, it is suppressed that the downstream communication is inhibited by the incident light IO for vehicle detection, and the downward communication is performed. Can be performed more reliably.

As shown in FIG. 7B, the shielding member 51 made of the cylindrical member 52 is not necessarily housed in the housing 31, and the bottom surface of the bottom portion of the housing 31 (the second bottom surface portion 37 of FIG. 5). You may make it attach in a hanging form from a lower surface.
However, if the shielding member 51 is exposed to the outside of the housing 31, the height of the beacon head 8 is enlarged and the appearance is deteriorated accordingly, so that the beacon head 8 is made as compact as possible and the appearance is maintained. The housing member 31 is preferably housed in the housing 31 as shown in FIG.

Although not shown in FIG. 7, a part (upper part) of the shielding member 51 is formed by attaching the shielding member 51 made of the cylindrical member 52 to the housing 31 so as to penetrate the bottom of the housing 31 vertically. May be accommodated in the housing 31.
Even in this case, the height dimension of the beacon head 8 can be suppressed as compared with the case where the entire shielding member 51 is exposed to the outside of the casing 31.

As shown in FIG. 7A, when the shielding member 51 made of the cylindrical member 52 is accommodated in the casing 31 (including a case where a part is accommodated), the light-emitting member 45 for vehicle sensing is used. It is preferable to arrange the light emitting point (specifically, the tip of the light emitting element 45 </ b> A) in the vicinity of the upper edge of the shielding member 51 in the housing 31.
In this case, compared to the case where the light emitting point is arranged at a position lower than the upper end edge of the shielding member 51, such as the central portion in the vertical direction of the cylindrical member 52, the incident light IO is made by the shielding member 51 made of the cylindrical member 52. The irradiation range can be narrowed down.

For this reason, it can suppress more reliably that incident light IO diffuses upstream, and the shielding effect of incident light IO by the shielding member 51 improves.
The cross-sectional shape of the cylindrical member 52 is not limited to a rectangular shape, and various other cross-sectional shapes such as various polygons and circles, or a D-shape in which a part is straight and the other part is curved may be employed. . Further, since it is sufficient that the upstream side of the light emitting member 45 can be shielded by the shielding member 51, a member having an open cross section where the downstream side is opened or a plate material that shields only the upstream side of the light emitting member 45 may be used.

[Variation 1 of the first embodiment]
FIG. 8A is a side cross-sectional view of a beacon head 8 according to Modification 1 of the first embodiment. Specifically, it is a side cross-sectional view of the beacon head 8 focusing on the light-emitting member 45 for vehicle detection.
8B and 8C are plan views of the vehicle sensing light emitting member 45 as viewed from below.

8A and 8B, the shielding member 51 includes a plurality of shielding plates 53 that extend along the road width direction. These shielding plates 53 are arranged at intervals in the vehicle traveling direction so as to shield the upstream sides of the rows arranged in the vehicle traveling direction.
That is, the shielding plate 53 is disposed at a position in contact with the light emitting element 45A on the upstream side of each light emitting element 45A constituting the row or at a distance slightly away from the light emitting element 45A, and hangs downward from the position. It extends in a shape. Although the fixing method of the shielding plate 53 is arbitrary, in the illustrated example, the upper end edge of the shielding plate 53 is fixed to the circuit board 44L.

The shielding plate 53 is not necessarily attached vertically to the circuit board 44L, and may be attached to the circuit board 44L so as to be inclined.
For example, in the example of FIG. 8A, if the lower end of the shielding plate 53 is inclined to the downstream side (the left side in the figure), a desired shielding effect can be secured even if the length of the shielding plate 53 is shortened. There is an advantage that the vertical dimension of the plate 53 can be shortened.

  Further, in the example of FIG. 8A, the shielding plate 53 passes through the transmission window portion 37L, but the shielding plate 53 may be entirely housed in the housing 31 or the housing 31. It may be exposed in a hanging manner from the bottom surface. This also applies to the case of a shielding piece 54 described later shown in FIG.

As shown in FIG. 8C, the shielding member 51 may be configured by a plurality of shielding pieces 54 arranged so as to shield the upstream side of the light emitting element 45A.
The shielding pieces 54 are arranged at positions on the upstream side of the respective light emitting elements 45A arranged in an arbitrary pattern on the circuit board 44L, in contact with the light emitting elements 45A or close to each other at a slight distance, It extends downwardly from that position. The method of fixing the shielding piece 54 is arbitrary, but a method of fixing the upper end edge to the circuit board 44L may be adopted as in the case of the shielding plate 52.

If the shielding plate 53 shown in FIGS. 8A and 8B is adopted, the shielding plate 53 shields the upstream side of the row, so that all the light emitting elements 45A are covered by one shielding member 51 made of the cylindrical member 52. Compared to the surrounding case (see FIG. 7), the effect of suppressing the diffusion of the incident light IO to the upstream side can be further improved.
In addition, since one shielding plate 53 shields the upstream side of the row composed of the plurality of light emitting elements 45A, compared with the case where the shielding piece 54 of FIG. 8C that individually shields each light emitting element 45A is employed. There is also an advantage that the number of parts of the shielding member 51 is reduced.

When the shielding pieces 54 shown in FIG. 8C are employed, the shielding pieces 54 shield the upstream side of the light emitting elements 45A, respectively, and therefore, all the light emitting elements 45A are surrounded by one shielding member 51 made of the cylindrical member 52. Compared to (see FIG. 7), the effect of suppressing the diffusion of the incident light IO to the upstream side can be further improved.
Further, in the case of the shielding piece 54 shown in FIG. 8C, the number of parts increases as compared with the shielding plate 53. For example, the arrangement of FIG. 8C in which a plurality of light emitting elements 45A are arranged in a staggered manner. Even in the case of a pattern, the upstream side of the light emitting element 45A can be reliably shielded.

For example, when the upper edge of the shielding plate 52 and the shielding piece 53 is fixed perpendicularly to the surface (lower surface) of the circuit board 44L, the height may be approximately 35 mm or more.
The reason for this is, for example, when assuming that the height of the shell part is 12.5 mm including the distance of the lead part and the directivity angle is 7 degrees or more, the height of the shielding plate 52 or the shielding piece 53 is 35 mm or more. This is because the directivity angle on the upstream side of the LED is reduced to about 7 ° by the shielding plate 52 or the small shielding piece 53, and the diffusion of the incident light IO to the upstream side is suppressed.

Here, in Modification 1 of FIG. 8, the size of the transmission window 37L in the casing 31 of the beacon head 8 is 40 mm × 40 mm in length and width, and the size of the light emitting member 45 (arrangement range of the light emitting elements 45A) is 25 mm in length and width. It shall be x 31 mm.
In this case, the width dimension of the shielding plate 52 may be at least equal to or larger than the width dimension (= 31 mm) of the light emitting member 45, but is set equal to or larger than the width dimension (= 40 mm) of the transmission window portion 37L. May be.

  In the examples of FIGS. 8A and 8B, instead of the shielding plate 53, a shielding member 51 made of a cylindrical member surrounding the row may be used for each row, or the example of FIG. 8C. In this case, instead of the shielding piece 54, a shielding member 51 made of a cylindrical member that takes in the periphery of each light emitting element 45A may be used.

[Modification 2 of the first embodiment]
FIGS. 9A to 9D are plan views of the beacon head 8 according to the second modification of the first embodiment when the transmission window 37L of the housing 31 is viewed from below.
In the example of FIGS. 9A to 9D, the shielding member 51 includes a bulging piece portion 55 that narrows the upstream portion (the right portion in FIG. 9) of the transmission window portion 37 </ b> L of the housing 31.

The bulging piece portion 55 is formed integrally with the bottom portion of the casing 31 and is a part of the most upstream row among the four rows arranged in the vehicle traveling direction (left-right direction in FIG. 9). It has a size that covers the light emitting element 45A from below.
The shape of the bulging piece 55 is not particularly limited, and is a curved shape shown in FIG. 9A, a substantially triangular shape shown in FIG. 9B, a substantially trapezoidal shape shown in FIGS. 9C and 9D, and the like. Various shapes can be employed.

  Even in the case of the shielding member 51 composed of the bulging piece portion 55, the upstream side of the vehicle sensing light emitting member 45 can be shielded to prevent the incident light IO from diffusing to the upstream side. Has the effect of.

The formation of the bulging piece 55 on the upstream side of the transmission window 37L can be regarded as shifting the geometric center of gravity of the transmission window 37L to the downstream side, so that the center of gravity is assumed to be the center of the transmission window 37L. This is the same as shifting the vehicle sensing light emitting member 45 to the upstream side.
Therefore, in the example of FIG. 9, as in the case of FIG. 10B, which will be described later, in order to prevent the incident light IO from diffusing upstream, the vehicle-sensing light emitting member 45 is placed on the transmission window 37 </ b> L. It can also be interpreted as an example of shifting to the upstream side.

[Modification 3 of the first embodiment]
10A and 10B are side cross-sectional views of the beacon head 8 of the optical beacon 4 according to Modification 3 of the first embodiment. Specifically, it is a side cross-sectional view of the beacon head 8 focusing on the light-emitting member 45 for vehicle detection.

In the second modification of the first embodiment, the shielding member 51 is not provided, but the light-emitting member 45 for vehicle detection is arranged inside the housing 31 so as to be shifted from the normal reference position in the height direction or the horizontal direction. This prevents the incident light IO from diffusing upstream.
For example, in the example of FIG. 10A, the vehicle-sensing light emitting member 45 is disposed away from the transmission window portion 37L by a height H that can suppress the diffusion of the incident light IO upstream. Further, in the example of FIG. 10B, the vehicle-detecting light emitting member 45 is shifted to the upstream side with respect to the transmission window 37L by a horizontal dimension L that can prevent the incident light IO from diffusing upstream. doing.

  In the normal optical beacon 4, the transmissive window portion 37L is wider than the light emitting member 45 so that the light emitted from all the light emitting elements 45A passes through the transmissive window portion 37L, and the tip of the light emitting element 45A ( The light emitting member 45 is disposed inside the housing 31 so that the lower end is as close as possible to the transmission window portion 37L and the plane position of the center of the light emission member 45 and the center of the transmission window portion 37L substantially coincide. Yes.

For example, exemplifying specific numerical values, the size of the transmission window portion 37L is 40 mm × 40 mm in length and width, the size of the light emitting member 45 (arrangement range of the light emitting elements 45A) is 25 mm × 31 mm in length, and the size of the transmission window portion 37L. The width is wider than the light emitting member 45 in the vertical and horizontal directions.
Further, in the case of an LED having a light emitting portion in a bullet shape, the height of the bullet portion is 9 mm, but the light emitting member 45 is arranged so that the distance between the transmission window portion 37L and the tip of the LED is about 3.6 mm. It arrange | positions in proximity to the transmissive window part 37L.

On the other hand, in the example of FIG. 10A, unlike the normal optical beacon 4, the tip (lower end) of the light emitting element 45A is not brought close to the transmission window portion 37L, but the tip is set to a predetermined height. By arranging the dimension H so as to be far away from the transmission window portion 37L, the incident light IO transmitted from the light emitting member 45 is prevented from diffusing upstream.
The predetermined height dimension H varies depending on the width difference between the light emitting member 45 and the transmission window 37L, the directivity angle of the light emitting element 45A, and the like, and may be specified by an irradiation experiment or the like.

On the other hand, in the example of FIG. 10B, the planar positions of the centers of the light emitting member 45 and the transmission window portion 37L are not matched as in the normal optical beacon 4, but the light emitting member is relative to the transmission window portion 37L. By shifting 45 from the upstream side by a predetermined horizontal dimension L, the incident light IO transmitted from the light emitting member 45 is prevented from diffusing upstream.
Note that the predetermined horizontal dimension L also varies depending on the width difference between the light emitting member 45 and the transmission window portion 37L, the directivity angle of the light emitting element 45A, and the like, and may be specified by an irradiation experiment or the like.

  In Modification 3 of the first embodiment, the vehicle sensing light emitting member 45 is separated from the transmission window portion 37L in the height direction (FIG. 10A), and the transmission window portion 37 is set in the horizontal direction. The policies for shifting (FIG. 10B) may be employed not only independently but also at the same time.

[Other Modifications of First Embodiment]
In the first embodiment described above (including the first to third modifications), it is preferable that the light emitting element 45A constituting the light sensing member 45 for vehicle sensing employs, for example, a light emitting element 45A having a directivity angle of 7 degrees or less. .
The reason is that, in order to more reliably suppress the diffusion of the incident light IO to the upstream side, it is more effective not only to suppress the incident light IO alone but also to reduce the directivity angle of the light emitting element 45A as much as possible. It is.

[Second Embodiment]
In the second embodiment, the incident light IO whose light emission timing is synchronized with the pulse of the downlink light DO is sent out from the light emitting member 45 for vehicle detection, thereby preventing the occurrence of optical signal interference itself. Solve the problem. Hereinafter, a specific example of this solution will be described with reference to the circuit configuration of FIG.

As indicated by a broken line arrow in FIG. 4, in the optical beacon 4 of the second embodiment, the communication IC 69 of the beacon controller 7 also outputs the pulse signal P <b> 1 generated by itself to the detection processing unit 71.
Then, the sensing processing unit 71 sets the pulse signal P2 output to the drive circuit 65 to the same light emission timing as the pulse signal P1 input from the communication IC 69.

Therefore, the incident light IO transmitted by the vehicle sensing light emitting member 45 is emitted at a timing synchronized with the downlink light DO transmitted by the light emitting member 42 for optical communication. The optical IO becomes an optical signal similar to the downlink optical DO.
For this reason, in road-to-vehicle communication using the optical beacon 4 having both the optical communication function and the vehicle sensing function, the downward communication is not hindered by the incident light IO for vehicle detection, and the downward communication is performed. It can be done reliably.

By the way, in the optical communication by the optical beacon 4, the periodic light emission of the downlink light DO is performed permanently so that the vehicle-mounted device 2 can detect that it has entered the communication area A.
Therefore, if the duration of the transmission of the incident light IO whose pulse is synchronized with the downlink light DO is also matched with the downlink light DO, the incident light IO is also emitted permanently. However, in this case, the vehicle-sensing light-emitting member 45 needs to have substantially the same durability and heat resistance as the light-emitting member 42 for optical communication, which causes a manufacturing cost to increase.

Therefore, the detection processing unit 71 of the present embodiment has a continuation period T1 in which the transmission of the incident light IO is continued and an interruption period T2 in which the transmission of the incident light IO is stopped longer than the pulse period of the downlink light DO. Pause control is repeated at a predetermined cycle.
If the pause control including the interruption period T2 is performed, the durability and heat resistance required for the light emitting member 45 for vehicle detection are made lower than those required for the light emitting member 42 for optical communication. It is possible to set, and it is possible to suppress an increase in production cost.

In the conventional optical beacon 4, the light emitting circuit for optical communication and the light emitting circuit for vehicle detection operate asynchronously. However, in the optical beacon 4 of the second embodiment, as described above, the downlink light DO and the incident light FIG. 12 is a diagram illustrating an example of a circuit configuration in the case where the light emission timings of the downlink light DO and the incident light IO are synchronized. As shown in FIG. 12, the light-emitting circuit includes an upper-side light communication light-emitting circuit (also referred to as a “downlink light-emitting circuit”) and a lower-stage vehicle light-emitting circuit.

As shown in FIG. 12, a flip-flop 101 and an AND circuit 102 are inserted in the vehicle sensing light emitting circuit for the purpose of synchronizing with the light communication light emitting circuit.
In addition, since these delays cause a delay of 60 ns and 30 ns, respectively, for a total of 90 ns, a circuit that causes the same 90 ns delay is also inserted in the output of the light emitting circuit for the downlink. As a result, the optical signals of the downlink light DO and the incident light IO are output in synchronization.

Conventionally, a vehicle sensing light-emitting circuit performs AND processing on an output signal from a downlink light-emitting circuit and an output signal from a vehicle sensing light-emitting circuit. In the time zone during which the LED is emitting light (duration T1 in FIG. 4), a pulse signal having the same cycle as that of the downlink light DO is output.
Therefore, as shown in FIG. 13, in the time zone T1 in which the vehicle detection output signal (pulse signal) was originally output, the pulse of the vehicle detection incident light IO synchronized with the pulse of the downlink light DO is The signal is output intermittently ON / OFF.

In this way, even when the downstream side of the downlink area DA and the upstream side of the vehicle sensing area (incidence area B) overlap, the downlink signal is appropriately transmitted in the in-vehicle device 2 of the vehicle 20. It becomes possible to receive.
However, in an area where the downlink light DO and the incident light IO overlap, the vehicle sensing incident light IO reaches the in-vehicle device 2 in addition to the downlink light DO. For this reason, after the vehicle-mounted device 2 enters the downlink area DA, it is assumed that the amount of light received by the vehicle-mounted device 2 sharply increases at the timing of entering the overlapping area.

When such a change in the amount of light exceeds a predetermined value, the function of adjusting the light receiving sensitivity included in the light receiving circuit of the in-vehicle device 2 does not work sufficiently, and the in-vehicle device 2 increases the light amount at the boundary of the overlapping area. Or, it is impossible to follow the decrease, and normal reception of the downlink optical DO may not be possible.
In order to cope with such a situation, in the present embodiment, it is desirable to adopt a light emitting method in which the increase and decrease in the amount of light is gently performed for the incident light IO for vehicle detection.

Specifically, the incident light IO consisting of a plurality of pulses in the duration T1 reaches the maximum light amount over, for example, 22 μs so that it does not become a regular intermittent rectangular shape, and the same at the fall. The amount of light converges to 0 over a period of time.
In this case, for example, as shown in the circuit diagram of FIG. 14, by adjusting at least one of the capacitance of the capacitor C and the constant of the resistor R to a predetermined value, the rising and falling of the incident light IO are made gentle or steep. Can be.

  As the electrostatic capacitance of the capacitor C and the resistance value of the resistor R are larger, the voltage change becomes gentler. Therefore, by adjusting one or both of them, for example, as shown in FIG. A plurality of pulses of the incident light IO can be gradually increased. Note that FIG. 15 illustrates the beginning of the duration T1, but the same applies to the trailing edge of the duration T1.

The additional circuit of FIG. 14 may be added to the portion where the voltage 24V is applied to the vehicle sensing LED of FIG.
Further, in FIG. 14, a portion written as “conventional sensing light pulse” corresponds to a signal on the input side of the flip-flop circuit 101 in FIG. 12, and is written as “sensing light pulse synchronized with the downlink”. This portion corresponds to the output signal from the AND circuit 102 in FIG.

  As a result of trial of the light emitting circuit of the present embodiment, in the case where the time constant is set so that the required rise time (the gradual increase time of the drive power source required to raise the light amount from 0 to the maximum value) is 22 μs, the in-vehicle device 2 The downstream end of the overlapping area (downlink signal light receiving area) where the BER (bit error rate) of the downlink signal on the side falls within a desired value is about 25 cm to 70 cm upstream from the point immediately below the beacon head 8. It became possible to set to.

That is, the downstream end position of the downlink area DA where the in-vehicle device 2 can receive the downlink signal can be set to 70 cm upstream from directly below the head, which is a desired point.
Note that the required rise time is preferably about 20 μs as described above, but it is possible to secure a desired downlink area DA by setting it to about 5 to 50 μs, more preferably 10 to 30 μs.

[Third Embodiment]
In 3rd Embodiment, even if incident light IO interferes with downlink light DO by giving the filter function which does not receive the optical signal below a predetermined frequency to vehicle equipment 2, only downlink light DO is carried out. This can solve the above-mentioned problems.
FIG. 11 is a functional block diagram illustrating an example of a circuit configuration of the light receiving unit 24 in the in-vehicle device 2 according to the third embodiment. Hereinafter, the circuit configuration of the in-vehicle device 2 according to the present embodiment will be described with reference to FIG.

As shown in FIG. 11, the optical receiver 24 of the in-vehicle device 2 includes a light receiving element 81, an amplifier 82, a filter circuit 83, a comparator 84, and a communication IC 85 in order from the left side in the drawing.
The amplifier 82 amplifies the electrical signal photoelectrically converted by the light receiving element 81 and outputs the amplified electrical signal to the filter circuit 83. The filter circuit 83 extracts at least a high-speed signal component having a transmission rate in the downlink direction (1024 kbps in this embodiment), and outputs the extracted high-speed signal to the comparator 84.

The comparator 84 compares the input high-speed signal with a threshold value, and outputs a digital reception signal (bit data) extracted by this comparison to the communication IC 85.
The communication IC 68 determines the transmission speed of the received signal using the idle pattern of the first 5 bytes and generates a reception clock, samples the bit data with the generated clock, and reproduces the downlink data included in the downlink frame. Then, the communication IC 68 sends the reproduced downlink data to the in-vehicle controller 21 (see FIG. 3).

In the in-vehicle device 2 of the present embodiment, the filter circuit 83 of the light receiving unit 24 includes a high-pass filter that blocks a received signal having a predetermined cutoff frequency (for example, 200 kHz) or less and allows a received signal having a frequency higher than that to pass. . Note that when the transmission rate of the downstream frame is 1024 kHz, the predetermined cutoff frequency may be less than 512 kHz.
On the other hand, in the optical beacon 4 of the present embodiment, the incident light IO for vehicle detection is composed of pulsed light having a dominant frequency component of 10 to 50 kHz.

Therefore, even if the incident light IO interferes with the downlink light DO in the portion from the downstream side of the downlink area DA, the electrical signal based on the incident light IO is blocked by the filter circuit 83, and the electricity based on the downlink light DO Only the signal is received.
For this reason, in road-to-vehicle communication using the optical beacon 4 having both the optical communication function and the vehicle sensing function, it is suppressed that the downstream communication is inhibited by the incident light IO for vehicle detection, and the downward communication is performed. Can be performed more reliably.

In the case of the optical beacon 4 that optically communicates with the in-vehicle device 2 of the third embodiment, the vehicle sensing so that the vehicle sensing light emitting member 45 emits the incident light IO having a light emission period duty ratio of approximately 50%. It is preferable to control the light emission time for.
The reason is that if the duty ratio of the emission period of the incident light IO is approximately 50%, the generation of harmonic component noise is most effectively suppressed in the frequency characteristics of the electrical signal obtained by photoelectric conversion of the incident light IO. is there.

  For this reason, if the road-vehicle communication system is comprised from the vehicle equipment 2 which has said filter function, and the optical beacon 4 which light-emits the incident light IO with said duty ratio, the filter circuit 83 by the side of the vehicle equipment 2 will become. It can function more effectively and receive downlink optical DO more reliably.

Various circuit configurations of the filter circuit 83 can be employed, but it is preferable to employ an RC configuration filter circuit in which a resistor and a capacitor are combined.
This is because an RC configuration filter circuit can be mounted more easily than other filter circuits using an operational amplifier or the like, and the labor required for a design change of the in-vehicle device 2 can be reduced.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the right of the present invention is shown not by the contents of the above-described embodiment but by the scope of claims, and is intended to include meanings equivalent to the scope of claims and all modifications within the scope.

(Appendix)
The characteristics of the optical beacon 4 according to the second embodiment described above will be described as a dependent claim of the present claim 10 as follows.
(Claim γ) The optical beacon according to claim 10, wherein the light emission control unit transmits the incident light so that a light amount of the incident light increases more gradually than a light amount of the downlink light.

  (Claim δ) The optical beacon according to claim 10 or γ, wherein the light emission control unit transmits the incident light so that the light amount of the incident light gradually decreases than the light amount of the downlink light. .

(Claim ε) The light emission control unit causes the incident light to be transmitted so that an increase degree of the light amount of the incident light is suppressed as compared with an increase degree of the light amount of the downlink light. Light beacon.
(Claim ζ) The light emission control unit causes the incident light to be transmitted so that a decrease degree of the light amount of the incident light is suppressed as compared with a decrease degree of the light amount of the downlink light. The optical beacon described in 1.

2 In-vehicle device 4 Optical beacon 7 Beacon controller 8 Beacon head (projector / receiver)
DESCRIPTION OF SYMBOLS 11 Transmission / reception unit 12 Sensor unit 20 Vehicle 21 Car-mounted controller 23 Light transmission part 24 Light reception part 42 Light emitting member 43 for optical communication Light receiving member 45 for optical communication Light emitting member 46 for vehicle detection Light receiving member 51 for vehicle detection Shielding Member 52 Cylindrical member 53 Shielding plate 54 Shielding small piece 55 Swelling piece 69 Communication IC
70 Main CPU
71 Sensing processing unit 83 Filter circuit

Claims (6)

A light-emitting circuit that emits incident light for vehicle detection to a light-emitting element for vehicle detection of an optical beacon having both an optical communication function and a vehicle detection function,
A switching element for causing the light emitting element to send and stop the incident light, a capacitor and a resistor,
Among the constants of the capacitor and the resistor, the possibility that the in-vehicle device can normally receive the downlink light for optical communication transmitted from the light emitting element for optical communication different from the light emitting element is increased. At least one of the light emitting circuits is adjusted. Adjustment of at least one of the capacitance of the capacitor and the constant of the resistance is performed in an area where both the incident light and the downlink light reach, where the bit error rate of the downlink signal in the in-vehicle device falls within a desired value. The light emitting circuit according to claim 1, which contributes to generation. An optical beacon having both an optical communication function and a vehicle sensing function, comprising the light emitting circuit according to claim 1 . An optical beacon having both an optical communication function and a vehicle sensing function,
A light emitting member for optical communication that transmits downlink light toward a road;
A vehicle-detecting light-emitting member for transmitting vehicle-detecting incident light to a downstream side of a downlink region where the in-vehicle device can receive the downlink light;
In the area where both the incident light and the downlink light reach, the on-board device is provided separately from the light emitting member for optical communication so that the possibility that the in-vehicle device can normally receive the downlink light is increased. An optical beacon, comprising: a light emitting circuit including a capacitor and a resistor for shaping the pulse of the incident light transmitted by the vehicle sensing light emitting member. The optical beacon according to claim 4 , wherein a bit error rate of a downlink signal in the in-vehicle device is within a desired value in the area. An optical beacon having both an optical communication function and a vehicle sensing function is a method of emitting incident light for vehicle sensing,
In an area where both the incident light and the downlink light for optical communication reach, an in-vehicle device is provided separately from the light emitting member for optical communication so that the possibility that the in-vehicle device can normally receive the downlink light is increased. A method of emitting incident light for vehicle detection by an optical beacon, characterized by shaping the pulse of the incident light transmitted by a light emitting member for vehicle detection.