JP6459653B2 - Optical communication device - Google Patents

Description

  The present invention relates to an optical communication apparatus capable of reducing power consumption.

  A road-to-vehicle communication system that performs optical communication with a vehicle and an optical communication device installed on the road is known. In road-to-vehicle communication systems, the optical beacon roadside unit of the optical communication device installed on the road and the optical beacon vehicle-mounted device of the optical communication device installed on the vehicle use two-way communication using optical communication by near infrared rays. Can be done. For example, Patent Literature 1 describes an optical beacon vehicle-mounted device. This optical beacon vehicle-mounted device includes a light receiving unit that receives an optical signal from an optical beacon roadside device, and a light emitting unit that transmits the optical signal to the optical beacon roadside device. Moreover, the optical beacon vehicle-mounted device does not cause the light emitting unit to emit light when information from the optical beacon roadside device is not necessary.

  Patent Document 2 describes an optical beacon roadside machine. The optical beacon roadside device includes a light receiving unit that receives an optical signal from the optical beacon vehicle-mounted device and a light emitting unit that includes a plurality of light emitting diodes. The number of light-emitting diodes is set to be larger than the number necessary for the light quantity of the optical signal to be at a level that can be received by the optical beacon vehicle-mounted device. When the light emitting diode deteriorates due to aging, the extra light emitting diodes except for the necessary number are turned on to secure the light quantity necessary for communication.

JP 2006-203330 A JP 2014-207646 A

  In recent years, in order to cope with a wide communication range, it is necessary to mount more light emitting diodes than a conventional optical communication device, and power consumption increases. In the optical beacon vehicle-mounted device of Patent Document 1, when the information from the optical beacon roadside unit is not required to reduce power consumption, the light emitting unit is not caused to emit light, but the light emitting unit is always constant during the period of transmitting the optical signal. The optical signal is sent out with the amount of light. Since the required light quantity of the transmitted optical signal decreases as the optical communication distance decreases, the optical beacon on-board device of Patent Document 1 may transmit an optical signal with an excessive light quantity.

  The optical beacon roadside device of Patent Document 2 did not consider reduction of power consumption. Moreover, the optical beacon roadside machine of patent document 2 needs to mount an excess light emitting diode previously.

  The present invention has been made in view of such circumstances, and an object thereof is to provide an optical communication apparatus capable of reducing power consumption.

An optical communication apparatus according to the present invention is an optical communication apparatus that transmits an optical signal to another apparatus, and includes a light emitting unit that has a plurality of light emitting elements and transmits the optical signal when the light emitting element is turned on, and the light emitting unit An acquisition unit that acquires information related to the distance to the other device that receives the optical signal transmitted by, and according to the information acquired by the acquisition unit, by changing the number of light emitting elements to be lit, and a light emission control unit for controlling the light intensity of the light emitting portion, the light emission control section is characterized Citea Rukoto to replace a light emitting element which does not light up the light-emitting element to be turned.

In the present invention, the optical communication device sends an optical signal to another device. The acquisition unit acquires information related to the distance between the optical communication device and another device. The current supplied to the light emitting element is controlled so that the light amount of the light emitting unit decreases as the distance indicated by the information acquired by the acquiring unit decreases . In this manner, the light signal can be transmitted with the required light amount by adjusting the light amount of the light emitting unit according to the information related to the distance. As a result, it is possible to suppress the transmission of an optical signal exceeding the necessary light amount, and to reduce power consumption. The light emission control unit adjusts the light amount of the light emitting unit by turning on or off the plurality of light emitting elements. Thus, power consumption can be reduced at low cost. Furthermore, the lighting time of each light emitting element can be made uniform by exchanging the light emitting element to be turned on and the light emitting element not to be turned on. Therefore, the lifetime of the light emitting element can be extended.

The optical communication device according to the present invention is characterized in that the light emission control unit counts a lighting time of each light emitting element and determines a light emitting element that is not to be lighted based on the lighting time .

In the present invention, the light emission control unit counts the lighting time of each light emitting element, and determines the light emitting elements that are not to be turned on based on the lighting time. Accordingly, it is Rukoto to ensure uniform the light emitting element each lighting time of.

  The optical communication apparatus according to the present invention is characterized in that the acquisition unit acquires a relative speed or a relative acceleration of the own apparatus and the other apparatus as the information relating to the distance.

  In the present invention, the relative speed or relative acceleration of the optical communication device and other devices is acquired. As described above, when the optical communication device is mounted on the vehicle, no other device is required, and information on the distance between the optical communication device and the other device is acquired by using the vehicle speed sensor or acceleration sensor of the vehicle. Therefore, an increase in cost can be suppressed.

  The optical communication apparatus according to the present invention is characterized in that the acquisition unit acquires position information of the own apparatus or the other apparatus as the information related to the distance.

  In the present invention, position information of an optical communication device or another device is acquired. In this way, when the optical communication device is mounted on a vehicle, no other equipment is required, and if the vehicle GPS (Global Positioning System) receiver is used, information relating to the distance between the optical communication device and the other device. Therefore, an increase in cost can be suppressed.

  The optical communication device according to the present invention includes a light receiving unit that receives an optical signal from the other device, and the acquisition unit acquires the intensity of the optical signal received by the light receiving unit as information relating to the distance. It is characterized by the above.

  In the present invention, the intensity of the optical signal received by the light receiving unit is acquired. As described above, since information related to the distance between the optical communication device and the other device can be acquired by using the light receiving unit of the optical communication device without using other equipment, the increase in cost is suppressed and wiring is performed. Can be simplified.

ADVANTAGE OF THE INVENTION According to this invention, the optical communication apparatus which can aim at the lifetime improvement of the light emitting element while reducing power consumption can be provided.

It is a schematic diagram which shows the structure of the optical beacon onboard equipment which concerns on Embodiment 1 of this invention. It is a schematic diagram which shows the example of arrangement | positioning of the light emitting element of a light emission part. It is the electric circuit diagram which simplified the light emission part and the drive circuit. It is a schematic diagram for demonstrating operation | movement of an optical beacon onboard equipment. It is a simplified electric circuit diagram for demonstrating the state of a drive circuit. It is a change figure of the number of lighting of a light emission part. It is a flowchart which shows the procedure of the process which a control part performs. It is a schematic diagram which shows the structure of the optical beacon onboard equipment which concerns on Embodiment 2 of this invention. It is a schematic diagram which shows the structure of the optical beacon onboard equipment which concerns on Embodiment 3 of this invention.

(Embodiment 1)
FIG. 1 is a schematic diagram showing a configuration of an optical beacon vehicle-mounted device 1 (optical communication device) according to Embodiment 1 of the present invention. The optical beacon vehicle-mounted device 1 is mounted on the vehicle 10 and performs transmission / reception with the optical beacon roadside device 2 which is another optical communication device installed on the road by optical communication. The optical beacon vehicle-mounted device 1 includes a light receiving unit 11, a light emitting unit 12, a receiving circuit 13, a driving circuit 14, and a control unit 15.

  The light receiving unit 11 is, for example, a photosensor, and receives a near-infrared light signal transmitted from the optical beacon roadside device 2. The light receiving unit 11 is connected to the receiving circuit 13. The receiving circuit 13 is connected to the control unit 15, amplifies the signal received by the light receiving unit 11, and outputs the amplified signal to the control unit 15.

  The light emitting unit 12 includes a plurality of light emitting elements, and transmits a near infrared light signal to the optical beacon roadside device 2 when the light emitting elements are turned on. The light emitting element is, for example, a light emitting diode. A drive circuit 14 is connected to the light emitting unit 12. The drive circuit 14 includes a plurality of switch elements that turn on and off the light emitting elements of the light emitting unit 12, and a power supply device that supplies power to each light emitting element of the light emitting unit 12. The switch element is, for example, a transistor. The power supply device includes a constant current circuit, for example.

  FIG. 2 is a schematic view showing an arrangement example of the light emitting elements of the light emitting unit 12. In this embodiment, an example in which the number of light emitting elements is twelve will be described. However, the number of light emitting elements is not limited thereto, and may be arbitrarily set as necessary. As shown in FIG. 2, the light emitting unit 12 includes light emitting diodes D1 to D12. Six light emitting diodes D1 to D12 are installed in two rows, upper and lower, for each row. In addition, arrangement | positioning of the light emitting diodes D1-D12 is not restricted to this, You may set arbitrarily as needed.

  FIG. 3 is a simplified electrical circuit diagram of the light emitting unit 12 and the drive circuit 14. As shown in FIG. 3, the transistors T <b> 1 to T <b> 4 are switching elements of the drive circuit 14. Each of the transistors T1 to T4 is connected in series to three light emitting diodes connected in series via current limiting resistors R1 to R4, so that four series connection bodies 121 to 124 are configured. The four series connection bodies 121 to 124 are connected in parallel between the positive electrode side and the negative electrode side of the power supply device 120.

  Specifically, in the series connection body 121, the anode of the light emitting diode D1 is connected to the positive electrode side of the power supply device 120, the cathode of the light emitting diode D1 is connected to the anode of the light emitting diode D2, and The cathode is connected to the anode of the light emitting diode D3, the cathode of the light emitting diode D3 is connected to one end of the current limiting resistor R1, and the other end of the current limiting resistor R1 is connected to the collector of the transistor T1, The emitter of T <b> 1 is connected to the negative electrode side of the power supply device 120.

  In the series connection body 122, the anode of the light emitting diode D4 is connected to the positive side of the power supply device 120, the cathode of the light emitting diode D4 is connected to the anode of the light emitting diode D5, and the cathode of the light emitting diode D5 is the light emitting diode D6. The cathode of the light emitting diode D6 is connected to one end of the current limiting resistor R2, the other end of the current limiting resistor R2 is connected to the collector of the transistor T2, and the emitter of the transistor T2 is connected to the power source. It is connected to the negative electrode side of the device 120.

  In the series connection 123, the anode of the light emitting diode D7 is connected to the positive side of the power supply device 120, the cathode of the light emitting diode D7 is connected to the anode of the light emitting diode D8, and the cathode of the light emitting diode D8 is the light emitting diode D9. The cathode of the light emitting diode D9 is connected to one end of the current limiting resistor R3, the other end of the current limiting resistor R3 is connected to the collector of the transistor T3, and the emitter of the transistor T3 is the power source. It is connected to the negative electrode side of the device 120.

  In the series connection body 124, the anode of the light emitting diode D10 is connected to the positive electrode side of the power supply device 120, the cathode of the light emitting diode D10 is connected to the anode of the light emitting diode D11, and the cathode of the light emitting diode D11 is light emitting diode D12. The cathode of the light emitting diode D12 is connected to one end of the current limiting resistor R4, the other end of the current limiting resistor R4 is connected to the collector of the transistor T4, and the emitter of the transistor T4 is the power source It is connected to the negative electrode side of the device 120.

  The bases of the transistors T1 to T4 are connected to the control unit 15, and are turned on / off according to instructions from the control unit 15.

  The control unit 15 is a computer device that includes, for example, a CPU, a memory, a signal processing unit, a timer, and the like, and performs processing, calculation, control, and the like of reception data from the reception circuit or transmission data output to the drive circuit 14. A vehicle speed sensor 3 that detects the speed of the vehicle 10 is connected to the control unit 15, and based on the vehicle speed detected by the vehicle speed sensor 3, the optical communication distance, that is, the optical beacon vehicle 1 and the optical beacon roadside device 2 Has a function of calculating the distance. Further, the control unit 15 has a function of controlling the light amount of the light emitting unit 12 by turning on or off a plurality of switches of the drive circuit 14 according to the calculated distance.

  As the optical communication distance decreases, the minimum light amount required for optical communication (hereinafter referred to as “required light amount”) decreases. For this reason, the control part 15 suppresses the increase in the power consumption by light emission more than required light quantity by controlling the light quantity of the light emission part 12 according to the distance of the optical beacon vehicle equipment 1 and the optical beacon roadside machine 2. FIG. it can. The memory of the control unit 15 stores a program and parameters for calculating the distance and controlling on / off of the transistors T1 to T4. The control unit 15 can realize the function by reading the program from the memory and executing it.

  FIG. 4 is a schematic diagram for explaining the operation of the optical beacon vehicle-mounted device 1. In FIG. 4, a substantially triangular area with hatching is an area P in which bidirectional communication can be performed between the optical beacon vehicle-mounted device 1 and the optical beacon roadside device 2. In the region P, the optical signal transmitted from the optical beacon roadside device 2 can be received by the optical beacon onboard device 1, and the optical signal transmitted from the optical beacon roadside device 1 can be received by the optical beacon roadside device 2.

  An example in which the vehicle 10 travels from a point A other than the region P via points B, C, D, and E will be described with reference to FIG. FIG. 5 is a simplified electric circuit diagram for explaining the state of the drive circuit. FIG. 6 is a change diagram of the lighting number of the light emitting unit 12. 5A to 5E respectively show the states of the transistors T1 to T4 when traveling along the points A to E in FIG. 6A to 6E show states of the light emitting diodes D1 to D12 when traveling along the points A to E in FIG.

  The optical beacon roadside unit 2 always transmits a near infrared light signal. When the vehicle 10 equipped with the optical beacon vehicle-mounted device 1 travels through the point A, no optical signal is transmitted. As shown in FIG. 5 and FIG. 6A, all the transistors T1 to T4 are turned off, and all the light emitting diodes D1 to D12 are turned off.

  When vehicle 10 reaches point B, it enters region P. At the point B, the light receiving unit 11 of the optical beacon vehicle-mounted device 1 receives an optical signal from the optical beacon roadside device 2. The received light signal is amplified and demodulated by the receiving circuit 13 and output to the control unit 15. The control unit 15 calculates the received data and transmits information related to the received data to another in-vehicle device such as a navigation device.

  In addition, the control unit 15 performs processing such as modulation on transmission data to be transmitted to the optical beacon roadside device 2 in the signal processing unit. The control unit 15 turns on the transistors T <b> 1 to T <b> 4 of the drive circuit 14 and transmits the processed transmission data as an optical signal via the light emitting unit 12. Thus, at point B, as shown in B of FIGS. 5 and 6, all the transistors T <b> 1 to T <b> 4 are turned on, and all the light emitting diodes D <b> 1 to D <b> 12 of the light emitting unit 12 are lit. Near-infrared light signals are sent to the optical beacon roadside device 2 by the light emitting diodes D1 to D12.

  The control unit 15 acquires the vehicle speed of the vehicle 10 via the vehicle speed sensor 3. The control unit 15 calculates the distance S between the optical beacon vehicle-mounted device 1 and the optical beacon roadside device 2 based on the vehicle speed of the vehicle 10.

  A method for calculating the distance S at the arbitrary point Q in the traveling direction of the vehicle 10 will be described. As shown in FIG. 4, each vertex of the region P is M, N, and O. The length S0 of the side MN, the length S3 of the side MO, and the size θ of the ridge N are measured in advance. In the memory of the control unit 15, the length S0 of the side MN and the size θ of ∠N are stored in advance as parameters for calculating the distance. The control unit 15 acquires the vehicle speed from the vehicle speed sensor 3 while measuring the travel time from the point B with a timer. The travel distance X from the point B to the point Q is calculated by the equation (1).

  Here, v is the vehicle speed of the vehicle 10, and t is the travel time from the point B. At the point Q, the distance S between the optical beacon vehicle-mounted device 1 and the optical beacon roadside device 2 is calculated by the equation (2) with S0 and θ stored in advance and X calculated by the equation (1). The

  While the vehicle 10 is traveling, the control unit 15 decreases the number of lighting elements of the light emitting unit 12 as the distance S decreases. For example, the control unit 15 compares the calculated distance S with a plurality of threshold values stored, and controls the switch element of the drive circuit 14 based on the comparison result. In the memory of the control unit 15, for example, a first threshold value S1, a second threshold value S2, and a third threshold value S3 are stored in advance as parameters for controlling the amount of light. The third threshold value S3 is equal to the length of the side MO of the region P, and S3 <S2 <S1 <S0. The first threshold value S1 is a maximum distance at which an optical signal transmitted by lighting of nine light emitting elements can be received. The second threshold value S2 is the maximum distance at which an optical signal transmitted by lighting of the six light emitting elements can be received. In the present embodiment, three threshold values are set, but the number of threshold values is not limited to three and may be arbitrarily set as necessary. The size of each threshold may be arbitrarily set based on the relationship between the light amount of the transmitted optical signal and the optical communication distance.

  The control unit 15 compares the calculated distance S with the first threshold value S1. When the vehicle 10 reaches the point C, the control unit 15 determines that the calculated distance S is the first threshold value S1, and turns off the transistor T1. Thus, at point C, as shown in C of FIG. 5, the transistor T1 is turned off and the transistors T2 to T4 are turned on. As shown in FIG. 6C, among the light emitting diodes D1 to D12 of the light emitting unit 12, the light emitting diodes D1 to D3 are turned off and the light emitting diodes D4 to D12 are turned on. An optical signal is sent to the optical beacon roadside machine 2 by the light emitting diodes D4 to D12.

  The control unit 15 acquires the vehicle speed of the vehicle 10 via the vehicle speed sensor 3. The control unit 15 calculates the distance S between the optical beacon vehicle-mounted device 1 and the optical beacon roadside device 2 based on the vehicle speed of the vehicle 10, and compares the calculated distance S with the second threshold value S2 stored.

  When the vehicle 10 reaches the point D, the control unit 15 determines that the calculated distance S is the second threshold value S2, and turns off the transistor T2. Thus, at point D, as shown in FIG. 5D, the transistors T1 and T2 are turned off and the transistors T3 and T4 are turned on. As shown in FIG. 6C, among the light emitting diodes D1 to D12 of the light emitting unit 12, the light emitting diodes D1 to D6 are turned off, and the light emitting diodes D7 to D12 are turned on. An optical signal is sent to the optical beacon roadside machine 2 by the light emitting diodes D7 to D12.

  The control unit 15 acquires the vehicle speed of the vehicle 10 via the vehicle speed sensor 3. The control unit 15 calculates the distance S between the optical beacon vehicle-mounted device 1 and the optical beacon roadside device 2 based on the vehicle speed of the vehicle 10, and compares the calculated distance S with a third threshold value S3 stored.

  When the vehicle 10 reaches the point E, the vehicle 10 leaves the region P. The control unit 15 determines that the calculated distance S is the third threshold value S3, and turns off the transistors T3 and T4. Thus, at the point E, as shown in E of FIGS. 5 and 6, all the transistors T <b> 1 to T <b> 4 are turned off, and all the light emitting diodes D <b> 1 to D <b> 12 of the light emitting unit 12 are turned off. The optical beacon vehicle-mounted device 1 does not send a near-infrared optical signal to the optical beacon roadside device 2.

  FIG. 7 is a flowchart illustrating a procedure of processing executed by the control unit 15. The control unit 15 executes a light emission control process when the light signal from the optical beacon roadside device 2 is received by the light receiving unit 11.

  The control unit 15 turns on all the transistors T1 to T4 to send an optical signal from the light emitting unit 12 to the optical beacon roadside device 2 (step S1), and the distance between the optical beacon vehicle-mounted device 1 and the optical beacon roadside device 2 S is calculated (step S2).

  The control unit 15 determines whether or not the distance S calculated in step S2 is equal to or less than the first threshold value S1 (step S3). When it determines with the distance S not being below 1st threshold value S1 (step S3: NO), the control part 15 returns a process to step S2.

  When it determines with the distance S being below 1st threshold value S1 (step S3: YES), the control part 15 turns off the transistor T1 (step S4), and the distance S of the optical beacon onboard equipment 1 and the optical beacon roadside machine 2 is set. Is calculated (step S5).

  The control unit 15 determines whether or not the distance S calculated in step S5 is equal to or less than the second threshold value S2 (step S6). When it determines with the distance S not being below 2nd threshold value S2 (step S6: NO), the control part 15 returns a process to step S5.

  When it determines with the distance S being below 2nd threshold value S2 (step S6: YES), the control part 15 turns off the transistor T2 (step S7), and the distance S of the optical beacon onboard equipment 1 and the optical beacon roadside machine 2 is set. Is calculated (step S8).

  The control unit 15 determines whether or not the distance S calculated in step S8 is equal to or less than the third threshold value S3 (step S9). If it is determined that the distance S is not less than or equal to the third threshold value S3 (step S9: NO), the control unit 15 returns the process to step S8.

  When it is determined that the distance S is equal to or less than the third threshold value S3 (step S9: YES), the control unit 15 turns off the transistors T3 and T4 (step S10) and ends the process.

  In this way, the control unit 15 calculates the distance S between the optical beacon vehicle-mounted device 1 and the optical beacon roadside device 2, and reduces the number of light-emitting diodes of the light emitting unit 12 that are turned on as the distance S decreases. Thereby, an optical signal can be transmitted with a required light quantity according to the optical communication distance. Thus, power consumption during the transmission period can be reduced. Further, since the distance S can be obtained by using the vehicle speed sensor 3 of the vehicle without using other equipment, an increase in cost can be suppressed. In the present embodiment, an acceleration sensor may be used instead of the vehicle speed sensor 3 and the travel distance X may be calculated based on the acceleration of the vehicle 10.

  Moreover, it is preferable that the control part 15 replaces the light emitting diode to be turned on and the light emitting diode not to be turned on. For example, in the area P that can communicate with the first optical beacon roadside device 2, the transistors T <b> 1 and T <b> 2 are turned off to reduce the light amount of the light emitting unit 12, but communication with the second optical beacon roadside device 2 is possible. The region P may be configured to reduce the light amount of the light emitting unit 12 by turning off the transistors T3 and T4. Further, the control unit 15 counts the lighting time of the light emitting diode of each series connection body, and when trying to turn off the light emitting diode, the transistor in the series connection body having the longest lighting time among the lighted series connection bodies. May be configured to turn off. Further, the control unit 15 may randomly determine a light emitting diode to be turned off. Thereby, the lighting time of each of the light emitting diodes D1 to D12 can be made uniform, and the life of the light emitting diode can be extended.

(Embodiment 2)
FIG. 8 is a schematic diagram showing a configuration of the optical beacon vehicle-mounted device 100 according to the second embodiment of the present invention. In the following description, the same configuration as that of the first embodiment is referred to, and the description thereof is omitted.

  In the optical beacon vehicle-mounted device 100, as shown in FIG. 8, the control unit 15 is connected to the GPS receiver 4 of the vehicle 10, acquires position information of the vehicle 10 from the GPS receiver 4, and uses the position information as the position information. Based on this, the travel distance X of the vehicle 10 is calculated, and the distance S between the optical beacon vehicle-mounted device 100 and the optical beacon roadside device 2 is calculated.

  As described above, similarly to the first embodiment, the control unit 15 can reduce the power consumption in the transmission period by reducing the number of light-emitting diodes of the light-emitting unit 12 as the distance S decreases. Since the distance can be obtained by using the GPS receiver 4 of the vehicle without using other equipment, an increase in cost can be suppressed.

(Embodiment 3)
FIG. 9 is a schematic diagram showing a configuration of the optical beacon vehicle-mounted device 101 according to the third embodiment of the present invention. In the following description, the same configuration as that of the first embodiment is referred to, and the description thereof is omitted.

  In the optical beacon onboard device 101, the control unit 15 obtains the distance S between the optical beacon onboard device 101 and the optical beacon roadside device 2 according to the intensity of the optical signal received by the light receiving unit 11, that is, the received light intensity. As shown in FIG. 9, when the light receiving unit 11 receives the optical signal from the optical beacon roadside device 2, the light receiving unit 11 outputs the received light intensity to the control unit 15. The memory of the control unit 15 stores in advance a table indicating the relationship between the received light intensity and the optical communication distance. As the optical communication distance decreases, the light receiving intensity of the light receiving unit 11 decreases, and the required light amount of the light emitting unit 12 also decreases. The control unit 15 can obtain the distance S between the optical beacon vehicle-mounted device 101 and the optical beacon roadside device 2 from the table based on the received light intensity from the light receiving unit 11.

  Thus, the control part 15 reduces the lighting number of the light emitting diode of the light emission part 12 with the reduction | decrease of the distance S of the optical beacon vehicle equipment 101 and the optical beacon roadside machine 2 similarly to Embodiment 1 and 2. FIG. As a result, power consumption in the transmission period can be reduced. In addition, since the distance S can be obtained by using the light receiving unit 12 without using other devices, it is possible to suppress an increase in cost and simplify wiring.

  In addition, in this Embodiment, since the required light quantity of the light emission part 12 reduces with the fall of received light intensity, the control part 15 is replaced with the distance S of the optical beacon onboard equipment 101 and the optical beacon roadside machine 2 instead. The light amount of the light emitting unit 12 may be controlled according to the received light intensity. The change relationship between the received light intensity and the required light amount of the light emitting unit 12 is measured in advance. For this reason, if one or a plurality of received light intensities are stored in the memory of the control unit 15 as parameters for controlling the amount of light instead of the first to third threshold values S1 to S3, the light received from the light receiving unit 11 is received. On / off of the transistors T1 to T4 can be controlled according to the strength. As described above, the control unit 15 does not need to calculate the distance S and can reduce the power consumption in the transmission period by reducing the number of light-emitting diodes of the light-emitting unit 12 that are turned on as the received light intensity decreases. .

  In each of the above embodiments, the distance S between the optical beacon vehicle-mounted device 1,100, 101 and the optical beacon roadside device 2 is calculated by the control unit 15, but is not limited to this, and is not limited to a millimeter wave radar or a laser rangefinder. A device for measuring the distance may be provided as the optical beacon device 1, 100, 101, and the distance S may be measured, or may be estimated by another method. It should be noted that the distance S between the optical beacon onboard devices 1, 100, 101 and the optical beacon roadside device 2 is not limited to a strict linear distance, and may have an error.

  In each of the above embodiments, the example in which three light emitting diodes are provided in each of the serial connection bodies 121 to 124 has been described. However, the number of light emitting diodes in each serial connection body is not limited to three, and is a number other than three. Also good. The number of serially connected bodies may be a number other than four. The number of light emitting diodes in each series connection body may be different.

  Moreover, although the above each embodiment demonstrated the example which uses an optical communication apparatus as an optical beacon vehicle equipment, an optical communication apparatus may be used as an optical beacon roadside machine. When the optical communication device is used as an optical beacon roadside device, the vehicle speed or position information of the vehicle 10 may be transmitted from the optical beacon onboard device to the optical beacon roadside device, and the distance S may be calculated by the optical beacon roadside device. Alternatively, the travel distance X or the distance S may be calculated by the optical beacon vehicle-mounted device, and the calculated travel distance X or the calculated distance S may be transmitted to the optical beacon roadside device. The optical communication device according to the present invention may be applied to optical communication between in-vehicle devices or may be applied to optical communication other than a vehicle.

  The embodiment disclosed this time is to be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the meanings described above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

1, 100, 101 Optical beacon vehicle-mounted device (optical communication device)
DESCRIPTION OF SYMBOLS 10 Vehicle 11 Light-receiving part 12 Light-emitting part 13 Receiving circuit 14 Drive circuit 15 Control part (Light emission control part, acquisition part)
2 Optical beacon roadside machine (optical communication equipment)
3 Vehicle speed sensor 4 GPS receiver

Claims (5)

In an optical communication device that sends an optical signal to another device,
A light-emitting unit having a plurality of light-emitting elements and transmitting the optical signal when the light-emitting elements are turned on;
An acquisition unit for acquiring information relating to a distance to the other device that receives the optical signal transmitted by the light emitting unit;
A light emission control unit that controls the light amount of the light emitting unit by changing the number of light emitting elements to be turned on according to the information acquired by the acquisition unit ;
The light emission control unit, an optical communication apparatus according to claim Citea Rukoto to replace a light emitting element which does not light up the light-emitting element to be turned. The optical communication apparatus according to claim 1, wherein the light emission control unit counts a lighting time of each light emitting element and determines a light emitting element that is not lighted based on the lighting time . The acquisition unit, the optical communication apparatus described as information relating to the distance, to claim 1 or claim 2, characterized in that you have to acquire the relative speed or relative acceleration of the host device and the other device. The acquisition unit, the information relating to the distance, the optical communication apparatus according to claim 1 or claim 2, characterized in that you have to acquire the position information of the own apparatus or the other device. A light receiving unit for receiving an optical signal from the other device;
The acquisition unit, the information relating to the distance, the optical communication apparatus according to claim 1 or claim 2, characterized in that you have to acquire the intensity of the received light signal by the light receiving unit.

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