JP2017134602A - Communication equipment and communication system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide communication equipment capable of continuously performing the repeated transmission of a signal while suppressing a deterioration in performance of a transmission part even when a speed of a vehicle is slow and a communication system having the communication equipment.SOLUTION: Vehicle communication equipment 3 is mounted on a vehicle 11. In the vehicle communication equipment 3, when a reception part 30 receives a request signal for requesting the transmission of a signal from a transmission part 20 of road side communication equipment 2, a transmission part 31 wirelessly performs the repeated transmission of a response signal to a reception part 21 of the road side communication equipment 2, and a control part 35 acquires vehicle speed information indicating the speed of the vehicle 11 from an in-vehicle communication part 32, and according as the speed of the vehicle 11 indicated by the vehicle speed information acquired from the in-vehicle communication part 32 is slow, the control part 35 adjusts transmission stop time from the transmission end of the response signal to the transmission resumption of the response signal to longer time as for the repeated transmission of the response signal performed by the transmission part 31.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a communication apparatus that repeatedly transmits a signal wirelessly, and a communication system including the communication apparatus.

  Currently, a communication system in which a light signal including traffic information related to traffic is transmitted wirelessly from a roadside device to a communication device mounted on a traveling vehicle has been proposed (see, for example, Patent Document 1). This communication system is a so-called optical beacon.

  In the communication system described in Patent Literature 1, the roadside device repeatedly transmits the first light signal wirelessly toward the vehicle traveling toward the roadside device. When the communication device mounted on the vehicle receives the first signal from the roadside device, the communication device wirelessly transmits the second signal of light to the roadside device. When the roadside device receives the second signal from the communication device, the roadside device wirelessly transmits a third signal of light including traffic information to the communication device. The communication device repeatedly transmits the second signal to the roadside machine at a predetermined cycle until the third signal is received from the roadside machine.

  Thereby, for example, the driver of the vehicle can acquire the traffic information included in the third signal, and the driver can appropriately drive the vehicle based on the acquired traffic information.

JP 2010-26897 A

  In a conventional communication system as described in Patent Document 1, a transmission area of a communication device in which a signal transmitted wirelessly by a communication device mounted on a vehicle is received by a roadside device, and a roadside device wirelessly. The transmitted signal does not match the reception area of the communication device that is received by the communication device. Each of the transmission area and the reception area depends on the performance of the roadside device and the vehicle communication device, for example, the light emission intensity.

  In many cases, a transmission area is formed inside the reception area. When the transmission area is formed in the reception area, the communication device mounted on the vehicle traveling toward the roadside device first enters the reception area, and then enters the transmission area existing in the reception area.

  The communication device receives the first signal from the roadside device when entering the reception area. As described above, when the communication device receives the first signal, the communication device repeatedly transmits the second signal to the roadside device at a predetermined period until the third signal is received from the roadside device. When the communication device enters the transmission area, the roadside device receives the second signal from the communication device and transmits the third signal to the communication device. The communication device receives the third signal from the roadside machine.

  For example, when the speed of the vehicle is low due to traffic jams, the period from when the communication apparatus enters the reception area to the transmission area, that is, the period during which the communication apparatus continuously transmits the second signal is long.

  In a communication device, a transmitter that wirelessly transmits a light signal to a roadside device has a light emitting element, for example, an LED (Light Emitting Diode), and the light emitting element emits light and stops light emission according to the signal to be transmitted. A signal is transmitted by performing alternately. When the signal to be transmitted is composed of “1” and “0”, for example, a state where the light emitting element emits light means “1” of the signal, and a state where the light emitting element stops emitting light is a signal. Means “0”.

  While a current is supplied to the light emitting element and the light emitting element emits light, the temperature of the light emitting element rises, and while the current supply to the light emitting element is stopped and the light emitting element stops emitting light, the light emitting element is cooled. As a result, the temperature of the light emitting element decreases. When the transmission unit repeatedly transmits the second signal at a predetermined cycle, the temperature of the light emitting element rises because the transmission stop time from the end of transmission of the second signal to the restart of transmission of the second signal is usually short. When the temperature of the light emitting element is equal to or higher than a predetermined temperature, the intensity of light emitted from the light emitting element when the same value of current is supplied to the light emitting element is reduced, and the performance of the transmitter is deteriorated.

  In a conventional communication system, when the speed of the vehicle is low, the transmission unit of the communication device repeatedly transmits the second signal. Therefore, the temperature of the light emitting element becomes equal to or higher than the predetermined temperature, and the performance of the transmission unit decreases. There is a risk of doing.

  As a communication system that solves this problem, the receiving unit of the communication device does not receive the third signal from the roadside device, and the period during which the transmitting unit of the communication device repeatedly transmits the second signal is equal to or longer than a predetermined period. In this case, a communication system that stops transmission of the second signal performed by the transmission unit is conceivable. However, in this communication system, since the communication device cannot receive the third signal from the roadside machine, there is a problem that the driver of the vehicle cannot obtain traffic information from the roadside machine.

  The present invention has been made in view of such circumstances, and the object of the present invention is to continue repeated signal transmission while suppressing deterioration in performance of the transmission unit even when the vehicle speed is low. It is in providing a communication apparatus which can be performed automatically, and a communication system provided with this communication apparatus.

  The communication device according to the present invention includes a transmission unit that repeatedly transmits signals wirelessly, and in the communication device mounted on the vehicle, an acquisition unit that acquires vehicle speed information indicating the speed of the vehicle, and the transmission unit performs An adjustment unit that adjusts the transmission stop time from the end of transmission of the signal to the resumption of transmission of the signal as the speed indicated by the vehicle speed information acquired by the acquisition unit is slower for repeated transmission of the signal; It is characterized by.

  In the present invention, the transmission unit repeatedly transmits a signal wirelessly using, for example, a light emitting element. Here, when the speed of the vehicle is low, the transmission stop time related to the repeated transmission of the signal is long. When the transmission stop time is long, the current supply to the light emitting element is stopped and the cooling period during which the light emitting element is cooled is long, so that the temperature rise of the light emitting element is suppressed, the deterioration of the performance of the transmission unit is suppressed, and The performance of the part 31 is maintained in a high state for a long time. The deterioration of the performance of the transmitter is, for example, a decrease in the intensity of light emitted from the light emitting element when the same value of current is supplied to the light emitting element. Even when the speed of the vehicle is low, the repeated transmission of the signal is not stopped and is continuously performed.

  The communication device according to the present invention is characterized in that the transmission unit ends the repeated transmission of the signal when the speed indicated by the vehicle speed information acquired by the acquisition unit is zero.

  In the present invention, when the speed of the vehicle is zero, that is, when the vehicle stops traveling, the transmission unit ends the repeated transmission of the signal. For example, when the receiving unit receives a specific signal, the transmitting unit is configured to end the repeated transmission of the signal. In the case where the transmission unit is configured in this way, when the reception unit does not receive a specific signal when the vehicle stops traveling, the reception unit is not specific even if the transmission unit repeatedly transmits the signal. The signal is not received, and repeated transmission of the signal in a state where the vehicle stops traveling is useless. When the vehicle stops traveling, the repeated transmission of the signal is terminated, so that useless power consumption is suppressed.

  A communication system according to the present invention includes the communication device described above and a second communication device that is installed outside the vehicle and wirelessly transmits a second signal to the communication device. A receiving unit that receives the second signal from the second communication device, and the transmitting unit repeatedly transmits the signal when the receiving unit receives the second signal.

  In the present invention, the transmission unit of the communication device repeatedly transmits the signal when the reception unit of the communication device receives the second signal from the second communication device installed outside the vehicle.

  In the communication system according to the present invention, the second communication device repeatedly transmits the second signal to the communication device until the second communication device receives the signal from the transmission unit of the communication device. When the reception of the second signal performed by the receiving unit is interrupted, the repeated transmission of the signal is terminated.

  In the present invention, the second communication device repeatedly transmits the second signal to the communication device until a signal is received from the transmission unit of the communication device. For example, when the traveling direction of the vehicle on which the communication device is mounted is changed and the reception of the second signal performed by the reception unit is interrupted, the transmission unit ends the repeated transmission of the signal. For this reason, the frequency | count that a signal is transmitted uselessly by a transmission part is suppressed.

  ADVANTAGE OF THE INVENTION According to this invention, even if it is a case where the speed of a vehicle is slow, repeating transmission of a signal can be performed continuously, suppressing degradation of the performance of a transmission part.

1 is a schematic diagram of a communication system in a first embodiment. It is a block diagram which shows the principal part structure of a communication system. It is a sequence diagram for demonstrating the outline | summary of operation | movement of a roadside communication apparatus and a vehicle communication apparatus. It is a flowchart which shows the procedure of the establishment process which a control part performs. It is a graph which shows the relationship between the speed of a vehicle, and transmission stop time. It is explanatory drawing of the operation | movement which the transmission part of a vehicle communication apparatus performs. 10 is a chart showing a relationship between vehicle speed and candidate time in the second embodiment. 10 is a flowchart illustrating a procedure of establishment processing performed by a control unit according to Embodiment 3. FIG. 11 is a block diagram showing a main configuration of a communication system in a fourth embodiment.

Hereinafter, the present invention will be described in detail with reference to the drawings illustrating embodiments thereof.
(Embodiment 1)
FIG. 1 is a schematic diagram of a communication system 1 according to the first embodiment. The communication system 1 includes a roadside communication device 2 mounted on a roadside machine 10 and a vehicle communication device 3 mounted on a vehicle 11. The roadside machine 10 is installed on the upper side of the vehicle 11. The roadside communication device 2 irradiates light related to the signal toward the road 12 on which the vehicle 11 travels, and the vehicle communication device 3 irradiates light related to the signal to the front upper side of the vehicle 11.
The roadside communication device 2 and the vehicle communication device 3 function as a second communication device and a communication device, respectively.

  The vehicle 11 travels on the road 12 toward the roadside machine 10. The roadside communication device 2 wirelessly transmits a light signal to the vehicle communication device 3 mounted on the vehicle 11 and wirelessly receives the light signal transmitted by the vehicle communication device 3. The vehicle communication device 3 wirelessly receives the light signal transmitted by the roadside communication device 2 and transmits the light signal to the roadside communication device 2 wirelessly.

  The transmission region of the vehicle communication device 3 where the signal transmitted by the vehicle communication device 3 is received by the roadside communication device 2 is the reception region of the vehicle communication device 3 where the signal transmitted by the roadside communication device 2 is received by the vehicle communication device 3 Is formed inside. For this reason, when the vehicle 11 travels toward the roadside machine 10, the vehicle communication device 3 first enters the reception area and then enters the transmission area. The vehicle communication device 3 exits the reception area after exiting the transmission area. While the vehicle communication device 3 is located in the transmission region or the reception region, the vehicle communication device 3 performs optical communication with the roadside communication device 2.

  FIG. 2 is a block diagram showing a main configuration of the communication system 1. The roadside communication device 2 includes a transmission unit 20, a reception unit 21, a storage unit 22, and a control unit 23. These are connected to the bus 24.

  The transmission unit 20 includes a light emitting element 20a such as an LED or a semiconductor laser. When a current is supplied to the light emitting element 20a, the light emitting element 20a emits light, and when the current supply to the light emitting element 20a is stopped, the light emitting element 20a stops emitting light. The transmission unit 20 wirelessly transmits a binary light signal to the vehicle communication device 3 in accordance with an instruction from the control unit 23. Specifically, in response to a signal to be transmitted to the vehicle communication device 3, the light emitting element 20a alternately repeats light emission and light emission stop to transmit a signal. For example, when the signal is composed of “1” and “0”, the state where the light emitting element 20a emits light means “1” of the signal, and the state where the light emitting element 20a stops emitting light is the signal. It means “0”.

  The receiving unit 21 includes a light receiving element 21a such as a phototransistor or a photodiode. The receiving unit 21 wirelessly receives a binary light signal from the vehicle communication device 3 based on the intensity of light received by the light receiving element 21a. For example, when the signal is composed of “1” and “0”, the intensity of the light received by the light receiving element 21a being equal to or higher than a predetermined intensity means “1” of the signal, and the light receiving element 21a receives the light. That the intensity of light is lower than a predetermined temperature means “0” of the signal. When receiving a signal from the vehicle communication device 3, the receiving unit 21 notifies the control unit 23 of the content of the received signal.

  The storage unit 22 is a nonvolatile memory. The storage unit 22 stores a control program. The control unit 23 has a CPU (Central Processing Unit) (not shown), and controls the operation of the transmission unit 20 by executing a control program stored in the storage unit 22. Thereby, the roadside communication device 2 performs optical wireless communication with the vehicle communication device 3.

The vehicle communication device 3 includes a reception unit 30, a transmission unit 31, an in-vehicle communication unit 32, a timer 33, a storage unit 34, and a control unit 35, which are connected to a bus 36. The in-vehicle communication unit 32 is connected to the communication line 4 provided in the vehicle 11 in addition to the bus 36.
The receiving unit 30 includes a light receiving element 30a such as a phototransistor or a photodiode. Similarly to the reception unit 21 of the roadside communication device 2, the reception unit 30 wirelessly receives the light signal transmitted by the transmission unit 20 of the roadside communication device 2 based on the intensity of the light received by the light receiving element 30a. When receiving a signal from the transmission unit 20 of the roadside communication device 2, the reception unit 30 notifies the control unit 35 of the content of the received signal.

  The transmission unit 31 includes a light emitting element 31a such as an LED or a semiconductor laser. When a current is supplied to the light emitting element 31a, the light emitting element 31a emits light, and when the current supply to the light emitting element 31a is stopped, the light emitting element 31a stops emitting light. The transmission unit 31 wirelessly transmits a binary light signal to the reception unit 21 of the roadside communication device 2 in the same manner as the transmission unit 20 of the roadside communication device 2 in accordance with an instruction from the control unit 35. Therefore, the light emitting element 31a alternately repeats light emission and light emission stop according to a signal to be transmitted to the receiving unit 21 of the roadside communication device 2.

  While the current is supplied to the light emitting element 31a, the temperature of the light emitting element 31a rises, and while the current supply to the light emitting element 31a is stopped, the light emitting element 31a is cooled and the temperature of the light emitting element 31a decreases. . When the temperature of the light emitting element 31a becomes equal to or higher than the predetermined temperature, the performance of the transmission unit 31 is deteriorated. The deterioration in the performance of the transmitter 31 is, for example, a decrease in the intensity of light emitted from the light emitting element 31a when the same current is supplied to the light emitting element 31a.

An ECU (Electronic Control Unit) or a GPS (Global Positioning System) receiver mounted on the vehicle 11 is connected to the communication line 4.
The ECU has a sensor that detects the speed of the vehicle 11. The ECU transmits vehicle speed information indicating the speed of the vehicle 11 detected by the sensor to the in-vehicle communication unit 32 of the vehicle communication device 3 via the communication line 4.

  The GPS receiver periodically receives radio waves from a plurality of GPS (Global Positioning System) satellites. The GPS receiver measures the position of the vehicle 11 based on the received radio wave each time it receives from a plurality of GPS satellites. Further, the GPS receiver has a clock function. The GPS receiver stores the measured position in association with the time when the position was measured. The GPS receiver calculates the speed of the vehicle 11 based on a plurality of stored positions and a plurality of times stored in association with these positions. The GPS receiver transmits vehicle speed information indicating the calculated speed of the vehicle 11 to the in-vehicle communication unit 32 of the vehicle communication device 3 via the communication line 4.

  The in-vehicle communication unit 32 receives vehicle speed information indicating the speed of the vehicle 11 from the ECU or the GPS receiver via the communication line 4. The vehicle speed information received by the in-vehicle communication unit 32 is acquired from the in-vehicle communication unit 32 by the control unit 35. The speed of the vehicle 11 indicated by the vehicle speed information acquired by the control unit 35 substantially matches the speed of the vehicle 11 at the time when the vehicle speed information is acquired. The control unit 35 functions as an acquisition unit.

The timer 33 starts and ends timing in accordance with instructions from the control unit 35. The time measured by the timer 33 is read by the control unit 35.
The storage unit 34 is a nonvolatile memory. The storage unit 34 stores a control program. Unique identification information is assigned to the vehicle communication device 3. The storage unit 34 stores identification information assigned to the vehicle communication device 3.

  The control unit 35 has a CPU (not shown), and controls the operation of the transmission unit 31 by executing a control program stored in the storage unit 34. Thereby, the vehicle communication device 3 performs optical wireless communication with the roadside communication device 2.

  FIG. 3 is a sequence diagram for explaining an outline of operations of the roadside communication device 2 and the vehicle communication device 3. The control unit 23 of the roadside communication device 2 instructs the transmission unit 20 to repeatedly transmit a request signal for requesting signal transmission wirelessly. When the vehicle communication device 3 mounted on the vehicle 11 traveling toward the roadside machine 10 enters the reception area, the reception unit 30 of the vehicle communication device 3 receives a request signal from the transmission unit 20 of the roadside communication device 2. Receive.

  When the receiving unit 30 receives the request signal, the control unit 35 of the vehicle communication device 3 executes an establishment process for establishing communication between the roadside communication device 2 and the vehicle communication device 3. In the establishment process, the control unit 35 instructs the transmission unit 31 to repeatedly transmit a response signal including the identification information of the vehicle communication device 3. The request signal corresponds to the second signal.

  When the vehicle communication device 3 mounted on the vehicle 11 enters the transmission area, the reception unit 21 of the roadside communication device 2 receives a response signal from the transmission unit 31 of the vehicle communication device 3. When the reception unit 21 receives the response signal, the control unit 23 of the roadside communication device 2 instructs the transmission unit 20 to end the repeated transmission of the request signal to the reception unit 30 of the vehicle communication device 3. Therefore, the transmission unit 20 of the roadside communication device 2 sends the request signal to the vehicle communication device 3 until the vehicle communication device 3 enters the transmission area and the reception unit 21 receives a response signal from the transmission unit 31 of the vehicle communication device 3. It repeatedly transmits to the receiving unit 30.

  The control unit 23 of the roadside communication device 2 instructs the transmission unit 20 to terminate the repeated transmission of the request signal to the transmission unit 20, and then includes the identification information included in the response signal and the traffic information. The signal is transmitted to the receiving unit 30 of the vehicle communication device 3. The traffic information is, for example, traffic jam information indicating a place where the traffic jam occurs. The control unit 23 causes the transmission unit 20 to transmit the traffic signal to the reception unit 30 of the vehicle communication device 3 while the vehicle communication device 3 is located in the reception area.

  When the receiving unit 30 receives a traffic signal including the identification information of the vehicle communication device 3 after the transmission unit 31 transmits the response signal, the vehicle communication device 3 communicates between the roadside communication device 2 and the vehicle communication device 3. As a result, the establishment process is terminated. The control unit 35 of the vehicle communication device 3 transmits a travel signal including travel information related to travel of the vehicle 11 after completing the establishment process. The travel information is, for example, time information indicating the time taken for the vehicle 11 to travel in a predetermined section. The travel information included in the travel signal is transmitted from the roadside communication device 2 to a server (not shown), for example, and used for analyzing traffic conditions.

  After the establishment process is completed, the receiving unit 30 of the vehicle communication device 3 continues to receive traffic signals from the transmission unit 20 of the roadside communication device 2 while the vehicle communication device 3 is located in the reception area. The content of the traffic information included in the traffic signal received by the receiving unit 30 is displayed on, for example, a display unit (not shown), and the driver of the vehicle 11 can acquire the traffic information. The driver can drive the vehicle 11 appropriately based on the acquired traffic information.

  Below, the establishment process which the control part 35 of the vehicle communication apparatus 3 performs is demonstrated in detail. FIG. 4 is a flowchart illustrating the procedure of the establishment process performed by the control unit 35. As described above, the control unit 35 executes the establishment process when the reception unit 30 receives the request signal transmitted from the transmission unit 20 of the roadside communication device 2.

  In the establishment process, the control unit 35 first acquires vehicle speed information from the in-vehicle communication unit 32 (step S1), and determines whether or not the speed of the vehicle 11 indicated by the acquired vehicle speed information is zero (step S2). . When it is determined that the speed of the vehicle 11 is zero (S2: YES), the control unit 35 ends the establishment process. When the establishment process is thus completed, the transmission unit 31 does not transmit a travel signal to the reception unit 21 of the roadside communication device 2.

  While the vehicle communication device 3 is in the reception area and the vehicle 11 is not traveling in a state where the vehicle communication apparatus 3 is not in the transmission area, the reception unit 30 of the vehicle communication device 3 is the transmission unit of the roadside communication device 2. Continue to receive request signals from 20. The control unit 35 of the vehicle communication device 3 executes an establishment process every time the reception unit 30 receives a request signal from the transmission unit 20 of the roadside communication device 2. The control unit 35 ends the establishment process without causing the transmission unit 31 to transmit a response signal unless the vehicle 11 resumes traveling.

  When it is determined that the speed of the vehicle 11 exceeds zero (S2: NO), the control unit 35 instructs the transmission unit 31 to send a response signal including identification information of the vehicle communication device 3 to the roadside communication device 2. It is made to transmit to the receiving part 21 (step S3). Next, the control part 35 sets transmission stop time based on the speed of the vehicle 11 which the vehicle speed information acquired by step S1 shows (step S4).

  As described above, in the establishment process, the control unit 35 instructs the transmission unit 31 to repeatedly transmit the response signal to the reception unit 21 of the roadside communication device 2. In step S4, the control unit 35 sets the transmission stop time to the travel time Tr (ms) required for the vehicle 11 to travel the predetermined distance D (m). Units are shown in parentheses.

Assume that the speed of the vehicle 11 is X (km / h). Here, “h” is an abbreviation for “hour” in English. The time required for the vehicle 11 to travel by 1 (m) is 60 × 60 / X (ms). Therefore, the traveling time Tr (ms) is calculated by the following equation (1).
Tr = D × 60 × 60 / X (1)
Expression (1) is stored in the storage unit 34. In step S4, the control unit 35 sets the transmission stop time to the travel time Tr calculated by substituting the speed of the vehicle 11 indicated by the vehicle speed information acquired in step S1 into X in the equation (1).

FIG. 5 is a graph showing the relationship between the speed of the vehicle 11 and the transmission stop time. As shown in FIG. 5, the higher the speed of the vehicle 11 acquired in step S1, the shorter the transmission stop time calculated in step S4. The lower the speed of the vehicle 11 acquired in step S1, the higher the speed calculated in step S4. The transmission stop time is long. For example, when the predetermined distance D is set to 0.3 (m) and the speed X of the vehicle 11 is 70 (km / h), the transmission stop time is set to 15.4 (ms). . Similarly, when the speed of the vehicle 11 is 40 (km / h), the transmission stop time is set to 27.0 (ms). When the speed of the vehicle 11 is 5 (km / h), the transmission stop time is set to 216.0 (ms).
As described above, the control unit 35 can appropriately set the transmission stop time using the equation (1).

  After executing step S4, the control unit 35 instructs the timer 33 to start timing (step S5), and determines whether or not the reception unit 30 has received a traffic signal from the transmission unit 20 of the roadside communication device 2. (Step S6). When it is determined that the reception unit 30 has not received a traffic signal (S6: NO), the control unit 35 determines whether or not the vehicle communication device 3 is located in the reception area (step S7).

  The fact that the receiving unit 30 of the vehicle communication device 3 does not receive a traffic signal means that the transmitting unit 20 of the roadside communication device 2 repeatedly transmits a request signal to the receiving unit 30 of the vehicle communication device 3. In step S7, the control part 35 determines with the vehicle communication apparatus 3 being located in a receiving area, when the receiving part 30 has received the request signal. The control part 35 determines with the vehicle communication apparatus 3 not being located in a receiving area, when reception of the request signal which the receiving part 30 is performing stops.

  When the control unit 35 determines that the reception unit 30 has received a traffic signal (S6: YES) or when it is determined that the vehicle communication device 3 is not located within the reception area (S7: NO), the timer 33 is instructed to end timing (step S8), and the establishment process is ended.

When the establishment process is completed because the reception unit 30 has received the traffic signal, as described above, the reception unit 30 receives the traffic signal repeatedly transmitted from the transmission unit 20 of the roadside communication device 2, and the transmission unit 31 A traveling signal is transmitted to the receiving unit 21 of the roadside communication device 2.
For example, when the establishment process is terminated because the vehicle 11 changes the traveling direction and the vehicle communication device 3 leaves the reception area, the transmission unit 31 does not transmit a travel signal.

  When the control unit 35 determines that the vehicle communication device 3 is located within the reception area (S7: YES), the time measured by the timer 33 is equal to or longer than the transmission stop time set in step S4. Whether or not (step S9). When it is determined that the measured time is less than the transmission stop time (S9: NO), the control unit 35 executes Step S6. The control unit 35 repeatedly executes steps S6 and S7 until the measured time becomes equal to or longer than the transmission stop time set in step S4.

  When it is determined that the timekeeping time is equal to or longer than the transmission stop time (S9: YES), the control unit 35 instructs the timer 33 to end timekeeping (step S10) and executes step S1 again.

  As described above, in the establishment process, when the vehicle 11 is traveling, the control unit 35 transmits until the reception unit 30 receives a traffic signal or the vehicle communication device 3 leaves the reception area. The response signal is repeatedly transmitted to the unit 31. Regarding the repeated transmission of the response signal performed by the transmission unit 31, the control unit 35 transmits the response signal from the end of transmission of the response signal to the resumption of transmission of the response signal as the speed of the vehicle 11 indicated by the vehicle speed information acquired from the in-vehicle communication unit 32 decreases. Adjust the stop time to a longer time. The control unit 35 also functions as an adjustment unit.

  FIG. 6 is an explanatory diagram of an operation performed by the transmission unit 31 of the vehicle communication device 3. FIG. 6 shows the operation of the transmission unit 31 when the vehicle 11 is gradually decelerated between the time when the vehicle communication device 3 enters the reception area and the time when the vehicle 11 enters the transmission area. As described above, when the vehicle communication device 3 enters the reception area and the reception unit 30 of the vehicle communication device 3 receives the request signal from the transmission unit 20 of the roadside communication device 2, the control unit 35 executes the establishment process. The transmitting unit 31 repeatedly transmits a response signal.

  As shown in FIG. 6, when the vehicle 11 decelerates, the transmission stop time from the end of transmission of the response signal to the restart of transmission of the response signal is extended. When the vehicle 11 is slow, the transmission stop time for repeated transmission of the response signal is long. When the transmission stop time is long, the current supply to the light emitting element 31a of the transmission unit 31 is stopped and the cooling period in which the light emitting element 31a is cooled is long. Therefore, the temperature rise of the light emitting element 31a is suppressed, and the transmission unit 31 Performance degradation is suppressed, and the performance of the transmission unit 31 is maintained in a high state for a long period. As described above, the deterioration of the performance of the transmission unit 31 is, for example, a decrease in the intensity of light emitted from the light emitting element 31a when a current having the same value is supplied to the light emitting element 31a.

  Even when the speed of the vehicle 11 is low, the repeated transmission of the response signal is continuously performed without being stopped. For this reason, even when the speed of the vehicle 11 is low, the receiving unit 30 of the vehicle communication device 3 receives a traffic signal from the transmission unit 20 of the roadside communication device 2, and the driver of the vehicle 11 Traffic information can be obtained from the roadside communication device 2 of the roadside.

  In addition, when the speed of the vehicle 11 is high, the transmission stop time related to the repeated transmission of the response signal is short, so that the receiving unit 21 of the roadside communication device 2 can be used while the vehicle communication device 3 is located in the transmission area. The response signal can be reliably received from the transmission unit 31 of the vehicle communication device 3 and the reception unit 30 of the vehicle communication device 3 has a high probability of receiving a traffic signal from the transmission unit 20 of the roadside communication device 2. For example, even when the vehicle communication device 3 is in the reception area and the vehicle 11 is greatly accelerated without entering the transmission area, the transmission stop time is short according to the speed of the vehicle 11. Therefore, the reception unit 21 of the roadside communication device 2 can reliably receive the response signal from the transmission unit 31 of the vehicle communication device 3.

  Furthermore, in the establishment process, when the speed of the vehicle 11 indicated by the vehicle speed information acquired by the control unit 35 from the in-vehicle communication unit 32 is zero, that is, when the vehicle 11 stops traveling, the transmission unit 31 receives the response signal. Repeat transmission ends. When the receiving unit 30 has not received a traffic signal when the vehicle 11 stops traveling, the receiving unit 30 transmits a response signal from the roadside communication device 2 of the roadside machine 10 even if the transmitting unit 31 repeatedly transmits a response signal. Is not received, and repeated transmission of the response signal in a state where the vehicle 11 stops traveling is useless. Therefore, in the vehicle communication device 3, when the vehicle 11 stops traveling, the transmission unit 31 repeatedly stops transmission, so that useless power consumption is suppressed.

  Even when the vehicle 11 stops traveling, as described above, the control unit 35 is established as long as the vehicle communication device 3 is in the reception area and not in the transmission area. Repeat the process. However, the control unit 35 ends the establishment process without repeatedly transmitting the response signal.

  Further, in the establishment process, the transmission unit 31 of the vehicle communication device 3 ends the establishment process when the reception of the response signal performed by the reception unit 30 is stopped due to, for example, a change in the traveling direction of the vehicle 11. Then, the repeated transmission of the response signal ends. For this reason, the frequency | count that a response signal is transmitted wastefully by the transmission part 31 is suppressed.

  The arithmetic expression used for setting the transmission stop time is not limited to the expression (1). For example, an equation that includes a set time Tc (ms) instead of the travel time Tr (ms) and that shortens the set time Tc (ms) as the speed X (km / h) of the vehicle 11 increases (1) You may use it instead of a formula. In this case, in step S4, the control unit 35 sets the transmission stop time to a set time Tc calculated by substituting the speed of the vehicle 11 indicated by the vehicle speed information acquired in step S1 into X of the arithmetic expression.

(Embodiment 2)
In step S4 of the establishment process in the first embodiment, the control unit 35 sets a transmission stop time using an arithmetic expression. However, the setting of the transmission stop time is not limited to the setting using an arithmetic expression.
In the following, the differences between the second embodiment and the first embodiment will be described. Since the configuration other than the configuration described later is the same as that of the first embodiment, the same reference numerals as those of the first embodiment are assigned to the same components as those of the first embodiment, and the description thereof is omitted. To do.

  In the storage unit 34 of the vehicle communication device 3 according to the second embodiment, the candidate time of the transmission stop time is stored in association with the speed of the vehicle 11 instead of the arithmetic expression. FIG. 7 is a chart showing the relationship between the speed of the vehicle 11 and the transmission stop time in the second embodiment.

  A candidate time of 200 (ms) is associated with the speed of the vehicle 11 that is less than 5 km / h. The speed of the vehicle 11 belonging to the range of 5 to 20 (km / h) is associated with 100 (ms) as a candidate time. The speed of the vehicle 11 belonging to the range of 20 to 40 (km / h) is associated with 50 (ms) as a candidate time. The speed of the vehicle 11 belonging to the range of 40 to 70 (km / h) is associated with 30 (ms) as a candidate time. The speed of the vehicle 11 that is 70 (km / h) or higher is associated with 10 (ms) as a candidate time.

In step S4 of the establishment process in the second embodiment, the control unit 35 sets the transmission stop time to a candidate time corresponding to the speed of the vehicle 11 indicated by the vehicle speed information acquired in step S1. For example, when the speed of the vehicle 11 indicated by the vehicle speed information acquired in step S1 is 3 (km / h), the control unit 35 reads a candidate time corresponding to 3 (km / h), and reads the read candidate time. Set to the transmission stop time. At this time, the transmission stop time is set to 200 (ms).
As described above, the control unit 35 can easily set the transmission stop time based on the contents stored in the storage unit 34.

(Embodiment 3)
In the establishment process in the first embodiment, the transmission stop time is set directly by the control unit 35. However, the configuration for setting the transmission stop time may be a configuration for indirectly setting the transmission stop time by changing other parameters.
In the following, the differences between the third embodiment and the first embodiment will be described. Since the configuration other than the configuration described later is the same as that of the first embodiment, the same reference numerals as those of the first embodiment are assigned to the same components as those of the first embodiment, and the description thereof is omitted. To do.

  FIG. 8 is a flowchart illustrating the procedure of the establishment process performed by the control unit 35 according to the third embodiment. In the establishment process in the third embodiment, steps S21, S22, S26 to S28, and S30 are the same as steps S1, S2, S6 to S8, and S10. The detailed explanation is omitted.

  In the establishment process, when it is determined that the speed of the vehicle 11 exceeds zero (S22: NO), the control unit 35 starts transmission of the next response signal after the transmission unit 31 starts transmission of the response signal. A transmission interval until the transmission is set is set (step S23).

  In step S23, a transmission interval is set in the same manner as the transmission stop time. That is, the control unit 35 sets the transmission interval to the travel time Tr (ms) required for the vehicle 11 to travel the predetermined distance D (m). Therefore, the expression (1) is stored in the storage unit 34. The control unit 35 sets the transmission interval to the travel time Tr calculated by substituting the speed of the vehicle 11 indicated by the vehicle speed information acquired in step S21 for X in the equation (1).

  After executing step S23, the control unit 35 instructs the timer 33 to start timing (step S24), and instructs the transmission unit 31 to send a response signal including identification information of the vehicle communication device 3 to the roadside communication device. 2 is transmitted to the second receiver 21 (step S25). The control unit 35 executes step S26 after executing step S25.

  When it is determined that the vehicle communication device 3 is located within the reception area (S27: YES), the control unit 35 determines whether the time measured by the timer 33 is equal to or longer than the transmission interval set in step S23. It is determined whether or not (step S29). When it is determined that the measured time is less than the transmission interval (S29: NO), the control unit 35 executes Step S26. The control unit 35 repeatedly executes steps S26 and S27 until the timed time becomes equal to or longer than the transmission interval set in step S23.

  When it is determined that the timekeeping time is equal to or longer than the transmission interval (S29: YES), the control unit 35 executes Step S30. Thereafter, the control unit 35 executes Step S21 again.

  As described above, in the establishment process in the third embodiment, the control unit 35 changes the transmission stop time by changing the transmission interval, that is, the cycle of transmitting the response signal. The transmission times of response signals repeatedly performed in the same establishment process are substantially the same. For this reason, changing the transmission interval is equivalent to changing the transmission stop time.

  The arithmetic expression used for setting the transmission interval is not limited to the expression (1). For example, an equation that includes a set time Tc (ms) instead of the travel time Tr (ms) and that shortens the set time Tc (ms) as the speed X (km / h) of the vehicle 11 increases (1) You may use it instead of a formula. In this case, in step S23, the control unit 35 sets the transmission interval to a set time Tc calculated by substituting the speed of the vehicle 11 indicated by the vehicle speed information acquired in step S21 into X of the arithmetic expression.

  In step S23, the control unit 35 may set the transmission interval in the same manner as in the second embodiment. In this case, in the storage unit 34, the candidate time of the transmission interval is stored in association with the speed of the vehicle 11 instead of the expression (1). The control unit 35 sets the transmission interval to a candidate time corresponding to the speed of the vehicle 11 indicated by the vehicle speed information acquired in step S21.

(Embodiment 4)
In the vehicle communication device 3 according to the first embodiment, the control unit 35 acquires vehicle speed information received by the in-vehicle communication unit 32 via the communication line 4. However, the control unit 35 may not acquire the vehicle speed information from the in-vehicle communication unit 32.
Hereinafter, the differences between the fourth embodiment and the first embodiment will be described. Since the configuration other than the configuration described later is the same as that of the first embodiment, the same reference numerals as those of the first embodiment are assigned to the same components as those of the first embodiment, and the description thereof is omitted. To do.

  FIG. 9 is a block diagram illustrating a main configuration of the communication system 1 according to the fourth embodiment. The vehicle communication device 3 according to the fourth embodiment includes other components other than the in-vehicle communication unit 32 among the components included in the vehicle communication device 3 according to the first embodiment, and these are the same as those in the first embodiment. It is connected to the. The vehicle communication device 3 according to the fourth embodiment includes a GPS receiving unit 50 instead of the in-vehicle communication unit 32, and the GPS receiving unit 50 is connected to the bus 36.

  The GPS receiver 50 receives radio waves, measures the position of the vehicle 11, stores the time, and calculates the speed of the vehicle 11 in the same manner as the GPS receiver described in the first embodiment. Vehicle speed information indicating the speed of the vehicle 11 calculated by the GPS receiver 50 is acquired by the controller 35. The speed of the vehicle 11 indicated by the vehicle speed information acquired by the control unit 35 substantially matches the speed of the vehicle 11 at the time when the vehicle speed information is acquired.

In step S <b> 1 of the establishment process in the fourth embodiment, the control unit 35 acquires vehicle speed information from the GPS receiving unit 50.
As described above, the vehicle communication device 3 may include the GPS receiving unit 50, and the control unit 35 may acquire vehicle speed information from the GPS receiving unit 50.

  In the second and third embodiments, the vehicle communication device 3 may include the GPS receiving unit 50 instead of the in-vehicle communication unit 32, and the control unit 35 may acquire vehicle speed information from the GPS receiving unit 50.

  The disclosed first to fourth embodiments are examples in all respects and should be considered not to be restrictive. The scope of the present invention is defined not by the above-mentioned meaning but by the scope of claims for patent, and is intended to include all modifications within the scope and meaning equivalent to the scope of claims for patent.

DESCRIPTION OF SYMBOLS 1 Communication system 11 Vehicle 2 Roadside communication apparatus 20 Transmission part 21 Reception part 3 Vehicle communication apparatus 30 Reception part 31 Transmission part 35 Control part (acquisition part, adjustment part)

Claims (4)

In the communication device installed in the vehicle, including a transmission unit that repeatedly transmits signals wirelessly,
An acquisition unit for acquiring vehicle speed information indicating the speed of the vehicle;
Regarding the repeated transmission of the signal performed by the transmission unit, the adjustment is performed such that the transmission stop time from the end of transmission of the signal to the resumption of transmission of the signal is adjusted to be longer as the speed indicated by the vehicle speed information acquired by the acquisition unit is slower And a communication device. The communication device according to claim 1, wherein the transmission unit ends the repeated transmission of the signal when the speed indicated by the vehicle speed information acquired by the acquisition unit is zero. The communication device according to claim 1 or 2,
A second communication device installed outside the vehicle and wirelessly transmitting a second signal to the communication device;
The communication device includes a receiving unit that receives the second signal from the second communication device,
The transmission unit repeatedly transmits the signal when the reception unit receives the second signal. The second communication device repeatedly transmits the second signal to the communication device until the signal is received from the transmission unit of the communication device,
4. The communication system according to claim 3, wherein the transmission unit ends the repeated transmission of the signal when reception of the second signal performed by the reception unit is interrupted. 5.

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