In-vehicle communication system, optical coupler and in-vehicle device

Abstract

The on-board communication system is provided with: an optical coupler including multiple optical transmission lines; and multiple on-board devices capable of communicating with one another via the optical coupler.

Description

[Technical field]

[0001] The present disclosure relates to an in-vehicle communication system, an optical coupler, and an in-vehicle device. This application claims priority based on Japanese Patent Application No. 2019-111044, filed on June 14, 2019, the disclosure of which is incorporated herein in its entirety. [Background technology]

[0002] Patent Document 1 (JP Patent Publication 2013-168865A) discloses an in-vehicle network system as follows. That is, the in-vehicle network system includes an in-vehicle control device having a memory for storing definition data that defines a part of a communication protocol used on an in-vehicle network that depends on the implementation on the in-vehicle network, and a communication protocol issuing device that issues the definition data to the in-vehicle control device. When the communication protocol issuing device receives a registration request requesting the in-vehicle control device to participate in the in-vehicle network from a registration device that causes the in-vehicle control device to participate in the in-vehicle network, the communication protocol issuing device performs authentication for the registration device, creates the definition data that complies with the implementation on the in-vehicle network, and returns it to the registration device. The registration device receives the definition data transmitted by the communication protocol issuing device, and requests the in-vehicle control device to store the received definition data in the memory. Then, the in-vehicle control device receives the definition data from the registration device, stores it in the memory, and communicates using the in-vehicle network in accordance with the communication protocol according to the part defined by the definition data. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2013-168865 A Summary of the Invention

[0004] The in-vehicle communication system of the present disclosure includes an optical coupler including a plurality of optical transmission paths, and a plurality of in-vehicle devices capable of communicating with each other via the optical coupler.

[0005] The optical coupler disclosed herein is an optical coupler used in an in-vehicle communication system having a first in-vehicle device, a second in-vehicle device, and a third in-vehicle device, and includes a first optical transmission path connecting the first in-vehicle device and the second in-vehicle device, and a second optical transmission path connecting the first in-vehicle device and the third in-vehicle device.

[0006] The vehicle-mounted device of the present disclosure is an vehicle-mounted device in an in-vehicle communication system equipped with an optical coupler including a plurality of optical transmission paths, and is equipped with a communication unit that communicates with other vehicle-mounted devices via the optical coupler, and a connection unit capable of connecting an optical fiber connected to the optical transmission path.

[0007] One aspect of the present disclosure may be realized not only as an in-vehicle communication system including such a characteristic processing unit, but also as a method having such characteristic processing steps, or as a program for causing a computer to execute such steps. Furthermore, one aspect of the present disclosure may be realized as a semiconductor integrated circuit that realizes part or all of the in-vehicle communication system.

[0008] One aspect of the present disclosure may be realized not only as an in-vehicle device having such a characteristic processing unit, but also as a method having such characteristic processing steps, or as a program for causing a computer to execute such steps. Furthermore, one aspect of the present disclosure may be realized as a semiconductor integrated circuit that realizes part or all of the in-vehicle device. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a diagram showing a configuration of an in-vehicle communication system according to an embodiment of the present disclosure. [Diagram 2] FIG. 2 is a diagram showing an example of information transmission timing in the in-vehicle communication system according to the embodiment of the present disclosure. [Diagram 3] FIG. 3 is a diagram illustrating an example of information transmission timing in the in-vehicle communication system according to the embodiment of the present disclosure. [Figure 4] FIG. 4 is a diagram showing an example of information transmission timing in the in-vehicle communication system according to the embodiment of the present disclosure. [Diagram 5] FIG. 5 is a diagram showing a configuration of a first modified example of an in-vehicle communication system according to an embodiment of the present disclosure. [Figure 6] FIG. 6 is a diagram showing a configuration of a second modified example of an in-vehicle communication system according to an embodiment of the present disclosure. [Figure 7] FIG. 7 is a diagram showing an example of information transmission timing in the second modification of the in-vehicle communication system according to the embodiment of the present disclosure. [Figure 8] FIG. 8 is a diagram showing a configuration of a third modified example of an in-vehicle communication system according to an embodiment of the present disclosure. [Figure 9] FIG. 9 is a diagram showing a configuration of a fourth modified example of an in-vehicle communication system according to an embodiment of the present disclosure. [Figure 10] FIG. 10 is a diagram illustrating an example of the branching ratio of each optical transmission line in the fourth modification of the in-vehicle communication system according to the embodiment of the present disclosure. [Figure 11] FIG. 11 is a diagram showing a configuration of a fifth modified example of an in-vehicle communication system according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] [Problem that this disclosure aims to solve] The in-vehicle network described in Patent Document 1 is provided with a communication gateway that relays communication data transmitted and received between in-vehicle ECUs (Electronic Control Units).

[0011] There is a demand for technology that goes beyond the technology described in Patent Document 1 and that enables construction of an excellent system for communication between in-vehicle devices.

[0012] The present disclosure has been made to solve the above-mentioned problems, and its purpose is to provide an in-vehicle communication system, an optical coupler, and an in-vehicle device that are capable of building an excellent system for communication between in-vehicle devices.

[0013] [Effects of this disclosure] According to the present disclosure, it is possible to construct an excellent system for communication between in-vehicle devices.

[0014] [Description of the embodiments of the present disclosure] First, the contents of the embodiments of the present disclosure will be listed and described.

[0015] (1) An in-vehicle communication system according to an embodiment of the present disclosure includes an optical coupler including a plurality of optical transmission paths, and a plurality of in-vehicle devices capable of communicating with each other via the optical coupler.

[0016] In this way, compared to a configuration in which electrical communication is performed between on-board devices using a switch device, for example, a configuration in which switching processing and the like is not required, communication control can be simplified, the use of active elements can be suppressed, and the weight of the transmission paths can be reduced, thereby realizing low-cost, small-sized, and lightweight on-board networks. In addition, characteristics such as EMC and transmission distance can be improved. Therefore, an excellent system for communication between on-board devices can be constructed.

[0017] (2) The multiple in-vehicle devices may include at least one master in-vehicle device that transmits synchronization information for synchronizing the transmission timing of each of the multiple in-vehicle devices, and time division multiplexing communication may be performed by each of the in-vehicle devices other than the master in-vehicle device transmitting information based on the synchronization information received from the master in-vehicle device.

[0018] With this configuration, communications between the in-vehicle devices can be smoothly performed with simple processing.

[0019] (3) At least one of the plurality of in-vehicle devices may be connected to all of the other in-vehicle devices with which it can communicate via the optical coupler.

[0020] With this configuration, timing control for time-division communication between the vehicle-mounted devices can be performed using optical couplers, so that the configuration of the transmission path between the vehicle-mounted devices can be simplified.

[0021] (4) The optical coupler may further include an optical transmission path for diagnosis, connecting the optical transmission path between the in-vehicle devices and a light receiving circuit external to the optical coupler, for detecting a state of the optical coupler.

[0022] With this configuration, it is possible to effectively diagnose deterioration over time, etc., in a transmission line configuration using optical couplers, where there is a relatively high need to monitor deterioration, such as the characteristics at the branching points of the transmission line, compared to a configuration in which electrical communication is performed between in-vehicle devices using a switch device, for example.

[0023] (5) In the optical coupler, an optical transmission path may be selectively provided between specific combinations of the in-vehicle devices among the plurality of combinations of the in-vehicle devices connected to the optical coupler.

[0024] With this configuration, in an in-vehicle network where the communication relationships between each in-vehicle device are fixed, unnecessary optical transmission paths can be eliminated in the optical coupler, enabling parallel transmission of information, thereby increasing the amount of communication in the in-vehicle network.

[0025] (6) The optical coupler may include a plurality of optical transmission paths branched at the optical coupler and connected to a common in-vehicle device.

[0026] With this configuration, it is possible to realize redundancy of the communication section of the vehicle-mounted device and redundancy of the communication path with a simple configuration that uses branching of the optical transmission line in the optical coupler.

[0027] (7) The optical coupler may include a plurality of optical transmission paths that are branched in the optical coupler and connected to the plurality of on-board devices, respectively, and that are set to have different branching ratios.

[0028] With this configuration, the communication stability can be set for each in-vehicle device using a simple method based on the design of the optical transmission path in the optical coupler, thereby improving the reliability of communication in the in-vehicle network.

[0029] (8) The synchronization information may specify a communication frame including a plurality of time slots, and the master in-vehicle device may assign the time slots to each of the in-vehicle devices in the synchronization information such that the time slots are switched at a timing when each of the in-vehicle devices is not transmitting a packet.

[0030] With this configuration, it is possible to prevent a situation in which a packet is divided and transmitted from an in-vehicle device across communication frames, resulting in the receiving in-vehicle device being unable to receive the packet, and communications between in-vehicle devices can be carried out smoothly with simple processing.

[0031] (9) An optical coupler according to an embodiment of the present disclosure is an optical coupler used in an in-vehicle communication system having a first in-vehicle device, a second in-vehicle device, and a third in-vehicle device, and includes a first optical transmission path connecting the first in-vehicle device and the second in-vehicle device, and a second optical transmission path connecting the first in-vehicle device and the third in-vehicle device.

[0032] In this way, compared to a configuration in which electrical communication is performed between on-board devices using a switch device, for example, a configuration in which switching processing and the like is not required, communication control can be simplified, the use of active elements can be suppressed, and the weight of the transmission paths can be reduced, thereby realizing low-cost, small-sized, and lightweight on-board networks. In addition, characteristics such as EMC and transmission distance can be improved. Therefore, an excellent system for communication between on-board devices can be constructed.

[0033] (10) An on-board device according to an embodiment of the present disclosure is an on-board device in an on-board communication system having an optical coupler including a plurality of optical transmission paths, and includes a communication unit that communicates with other on-board devices via the optical coupler, and a connection unit capable of connecting an optical fiber connected to the optical transmission path.

[0034] In this way, compared to a configuration in which electrical communication is performed between on-board devices using a switch device, for example, a configuration in which switching processing and the like is not required, communication control can be simplified, the use of active elements can be suppressed, and the weight of the transmission paths can be reduced, thereby realizing low-cost, small-sized, and lightweight on-board networks. In addition, characteristics such as EMC and transmission distance can be improved. Therefore, an excellent system for communication between on-board devices can be constructed.

[0035] (11) The communication unit may be capable of communicating with a plurality of other in-vehicle devices via the optical coupler, and may be capable of relaying information received from the other in-vehicle devices to another in-vehicle device other than the other in-vehicle devices via the optical coupler.

[0036] With this configuration, for example, an in-vehicle device can achieve relay processing between other in-vehicle devices with a simple configuration including a single optical transceiver.

[0037] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals, and the description thereof will not be repeated. In addition, at least some of the embodiments described below may be arbitrarily combined.

[0038] FIG. 1 is a diagram showing a configuration of an in-vehicle communication system according to an embodiment of the present disclosure.

[0039] 1, the in-vehicle communication system 301 includes an optical coupler 1, a plurality of optical fibers 91, and a plurality of in-vehicle devices 101. The in-vehicle communication system 301 is mounted on a vehicle 401.

[0040] In the example shown in FIG. 1, the in-vehicle communication system 301 includes four in-vehicle devices 101, but is not limited to this and may include three, five or more in-vehicle devices 101.

[0041] The in-vehicle device 101 is, for example, an ECU (Electronic Control Unit). In this example, the in-vehicle communication system 301 includes, as the in-vehicle device 101, ECU1 to ECU4.

[0042] The in-vehicle device 101 is, for example, a TCU (Telematics Communication Unit), a central gateway (CGW), a human-machine interface, a camera, a sensor, a driving assistance device, a navigation device, and the like.

[0043] The connection relationships of the on-board devices 101 in the on-board network of the vehicle 401 are, for example, fixed. Also, the communication relationships, i.e., the relationships of information exchange, of the on-board devices 101 in the on-board network of the vehicle 401 are, for example, fixed.

[0044] The optical coupler 1 and each of the in-vehicle devices 101 are connected to each other, for example, by an optical fiber 91. That is, a plurality of optical fibers 91 are connected between the optical coupler 1 and each of the in-vehicle devices 101.

[0045] A plurality of on-vehicle devices 101 in the on-vehicle communication system 301 can communicate with each other via the optical coupler 1 and the optical fiber 91. Information is exchanged between the on-vehicle devices 101 using, for example, Ethernet (registered trademark) frames conforming to IEEE802.3. The transmission speed of the Ethernet frame is, for example, 1 Gbps (Giga bits per second) or 10 Gbps.

[0046] More specifically, the in-vehicle device 101 includes a communication unit 51, a connection unit 52, and a storage unit 53. The optical coupler 1 includes a plurality of optical transmission paths 11 that connect the in-vehicle devices 101 together. The optical fibers 91 are connected to the corresponding optical transmission paths 11 in the optical coupler 1.

[0047] 1, in the optical coupler 1, the optical transmission path is branched, so that all pairs of on-board devices 101 are connected via the optical transmission path 11. The multiple optical transmission paths 11 connect different pairs of on-board devices 101 via optical fibers 91.

[0048] More specifically, the optical coupler 1 includes an optical transmission path 11 connected between ECU1 and ECU2, an optical transmission path 11 connected between ECU1 and ECU3, an optical transmission path 11 connected between ECU1 and ECU4, an optical transmission path 11 connected between ECU2 and ECU3, an optical transmission path 11 connected between ECU2 and ECU4, and an optical transmission path 11 connected between ECU3 and ECU4.

[0049] The optical coupler 1 is, for example, a waveguide splitter or an optical fiber coupler. More specifically, the optical transmission line 11 in the optical coupler 1 can be formed of, for example, a glass optical waveguide, a polymer optical waveguide, a semiconductor optical waveguide, or an optical fiber.

[0050] In the in-vehicle device 101, the connection portion 52 is capable of connecting an optical fiber 91. The optical fiber 91 is connected to the in-vehicle device 101 at the connection portion 52 by a connector, adhesive, or the like.

[0051] The communication unit 51 includes an optical transceiver 61 and communicates with other in-vehicle devices 101 by transmitting and receiving optical signals including Ethernet frames via the optical coupler 1 and the optical fiber 91 .

[0052] More specifically, the communication unit 51 sets the MAC (Medium Access Control) address of the destination in-vehicle device 101 and its own MAC address as the destination MAC address and the source MAC address, respectively, in the Ethernet frame. Then, the communication unit 51 generates an optical signal including the Ethernet frame in the optical transceiver 61, and transmits it to the other in-vehicle device 101 via the optical fiber 91 and the optical coupler 1.

[0053] Furthermore, communication unit 51 receives an optical signal in optical transceiver 61 via optical coupler 1 and optical fiber 91, and acquires an Ethernet frame contained in the optical signal. Communication unit 51 checks the destination MAC address of the Ethernet frame, and if the destination MAC address is its own MAC address, performs various processes using information contained in the Ethernet frame. On the other hand, if the destination MAC address of the Ethernet frame is not its own MAC address, communication unit 51 discards the Ethernet frame.

[0054] For example, the storage unit 53 stores the MAC address of the in-vehicle device 101 itself and the MAC addresses of the in-vehicle devices 101 that are destinations of various information. The communication unit 51 references each MAC address stored in the storage unit 53 and generates an Ethernet frame.

[0055] In addition, the in-vehicle device 101 is not limited to a configuration that communicates using Ethernet frames, and may be configured to communicate by including data in other formats in optical signals, such as frames conforming to the CAN (Controller Area Network) (registered trademark) standard.

[0056] FIG. 2 is a diagram showing an example of information transmission timing in the in-vehicle communication system according to the embodiment of the present disclosure.

[0057] 2, the multiple in-vehicle devices 101 in the in-vehicle communication system 301 include a master in-vehicle device that is an in-vehicle device 101 that transmits synchronization information for synchronizing the transmission timing of each of the multiple in-vehicle devices 101. In the in-vehicle communication system 301, each in-vehicle device 101 other than the master in-vehicle device transmits information at a timing according to the synchronization information received from the master in-vehicle device, that is, based on the synchronization information, thereby performing time division multiplexing communication.

[0058] In order to transmit the synchronization information to each on-board device 101, at least one of the multiple on-board devices 101 in the on-board communication system 301 is connected to all the other on-board devices 101 via the optical coupler 1 and the optical fiber 91. That is, at least one of the multiple on-board devices 101 can communicate with all the other on-board devices 101 via the optical coupler 1 and the optical fiber 91. In this example, the ECU 1 that transmits the synchronization information is connected to ECUs 2 to 4.

[0059] More specifically, after being started, the ECU 1, as the master in-vehicle device, broadcasts an Ethernet frame, which stores synchronization information indicating the start timing of a communication frame, at a predetermined period.

[0060] The ECU 1 is not limited to a configuration in which synchronization information is included in an optical signal and transmitted, but may be configured to transmit, for example, an electrical signal indicating the start timing of a communication frame as synchronization information to each ECU via a dedicated line.

[0061] Furthermore, the ECU 1 may be configured to transmit information other than the synchronization information, or may be configured to transmit only the synchronization information.

[0062] In the in-vehicle communication system 301, the ECUs 1 to 4 transmit information at timings according to the synchronization information, thereby performing time division multiplexing communication. More specifically, the ECU 1 transmits information at timings according to the synchronization information it has generated. The ECUs 2 to 4 transmit information at timings according to the synchronization information received from the ECU 1.

[0063] For example, the synchronization information defines a communication frame including a plurality of time slots. In the example shown in Fig. 2, the communication frame defined by the transmission interval of the synchronization information includes four time slots TS1 to TS4. The time slots TS1 to TS4 are assigned to ECU1 to ECU4, respectively. Each ECU is permitted to transmit an Ethernet frame in the time slot assigned to itself, and waits for Ethernet frames from other ECUs in the other time slots. That is, ECU1 to 4 transmit and receive information in a time-division manner.

[0064] In the in-vehicle communication system 301, the communication frame length and the time slot length may be stored in the memory unit 53 of each ECU, or the communication frame length and the time slot length may be included in the synchronization information transmitted from the ECU 1.

[0065] Furthermore, in the in-vehicle communication system 301, the communication frame length and the time slot length may be dynamically assigned according to the amount of data transmitted by each ECU. That is, the communication frame length may be different for each communication frame, and the lengths of the time slots TS1 to TS4 may be different from one another.

[0066] Specifically, for example, after transmitting an Ethernet frame in a time slot assigned to each of ECUs 2 to 4, ECUs 2 to 4 notify ECU 1 of the remaining amount of data to be transmitted, i.e., the amount of data that has not been transmitted. ECU 1 calculates the communication frame length and the time slot length of ECUs 1 to 4 based on the remaining amount of data notified by ECUs 2 to 4 and its own amount of data that has not been transmitted, and transmits the calculation result together with the synchronization information.

[0067] For example, the master in-vehicle unit assigns time slots to each in-vehicle unit 101 in synchronization information such that the time slots are switched at a timing when each in-vehicle unit 101 does not transmit a packet such as an Ethernet frame.

[0068] Specifically, in the case of Ethernet, the minimum and maximum values ​​of the Ethernet frame length and the minimum value of the interframe gap are specified by the standard, and values ​​within these ranges can be set for the Ethernet frame. Therefore, ECU1 sets the length of each time slot in the communication frame so that the ECU permitted to transmit the Ethernet frame is switched in the interframe gap between temporally adjacent Ethernet frames transmitted by different ECUs.

[0069] Fig. 3 is a diagram showing an example of information transmission timing in the in-vehicle communication system according to the embodiment of the present disclosure, in which the data length of the Ethernet frame is a fixed value.

[0070] Referring to FIG. 3, each of ECUs 1 to 4 is assigned a time slot having a length sufficient for transmitting two Ethernet frames.

[0071] The ECUs 2 to 4 notify the number of Ethernet frames to be transmitted in a communication frame or the total data length to the ECU 1. The ECU 1 assigns time slots to the ECUs 2 to 4 based on the contents of the notifications from the ECUs 2 to 4.

[0072] Alternatively, the ECU 1 may determine the number of Ethernet frames transmittable in a time slot or the total data length without receiving any notification from the ECUs 2 to 4, and notify the ECUs 2 to 4 of the result.

[0073] Alternatively, a time slot having a length enabling transmission of a different number of Ethernet frames may be assigned to each ECU.

[0074] Fig. 4 is a diagram showing an example of information transmission timing in the in-vehicle communication system according to the embodiment of the present disclosure, in which the data length of the Ethernet frame is variable.

[0075] Referring to FIG. 4, ECUs 1, 2, and 4 are assigned time slots long enough to transmit standard Ethernet frames, and ECU 3 is assigned time slots long enough to transmit jumbo frames, and ECUs 1 to 4 are assigned time slots long enough to transmit one, three, one, and two Ethernet frames, respectively.

[0076] The ECUs 2 to 4 notify the ECU 1 of the number of Ethernet frames that they wish to transmit in the communication frame, and the data length of the Ethernet frames or the total data length.

[0077] Alternatively, the ECU 1 may determine the number of Ethernet frames transmittable in a time slot and the data length of the Ethernet frames or the total data length without receiving notifications from the ECUs 2-4, and notify the ECUs 2-4 of the results.

[0078] [Variation 1] 5 is a diagram showing a configuration of a first modified example of an in-vehicle communication system according to an embodiment of the present disclosure. Contents other than those described below are the same as those of the in-vehicle communication system 301 shown in FIG.

[0079] 5, the first modification of the in-vehicle communication system 301 includes an optical coupler 2, a plurality of optical fibers 91, a plurality of in-vehicle devices 101, an optical fiber 92, and a diagnostic circuit 151. The diagnostic circuit 151 includes a light receiving circuit 71 having a photodiode. Compared to the optical coupler 1, the optical coupler 2 further includes an optical transmission path 12.

[0080] The optical transmission path 12 is a transmission path that connects the optical transmission path 11 between the in-vehicle device 101 and a light receiving circuit 71 outside the optical coupler 2, and is used to detect the state of the optical coupler 2. That is, the optical transmission path 12 is connected to the light receiving circuit 71 in the diagnostic circuit 151 via an optical fiber 92.

[0081] The optical transmission line 12 is, for example, an optical transmission line branched off from the optical transmission line from the ECU 2 to the ECUs 1, 3, and 4.

[0082] The diagnostic circuit 151 uses the light receiving circuit 71 to measure the intensity of the optical signal received via the optical transmission line 12 and the optical fiber 92, and detects an abnormality based on the measurement result (hereinafter also referred to as measurement result 1).

[0083] For example, the diagnostic circuit 151 detects the state of the optical coupler 2, such as an abnormality in the optical coupler 2, based on the measurement result 1 and the measurement result 2 in the ECU 2 of the intensity of the optical signal transmitted from the ECU 2. More specifically, the diagnostic circuit 151 receives from the ECU 2 the Ethernet frame M in which the measurement result 2 is stored, and compares the measurement results 1 and 2 to detect an abnormality related to a change in the branching ratio of the optical transmission path 11 in the optical coupler 2, an increase in loss, and the like.

[0084] The configuration is not limited to one in which diagnostic circuit 151 detects an abnormality in optical coupler 2, but may instead be one in which diagnostic circuit 151 transmits measurement result 1 to, for example, ECU 3, and ECU 3 detects an abnormality based on measurement result 1, etc.

[0085] In addition, the in-vehicle communication system 301 may not include the diagnostic circuit 151 and the optical transmission path 12, and may be configured such that, for example, the ECU2 or the ECU3 detects an abnormality based on the measurement result in the ECU2 of the strength of the optical signal transmitted from the ECU2 and the measurement result in the ECU3 of the strength of the optical signal transmitted from the ECU2.

[0086] [Variation 2] 6 is a diagram showing a configuration of a second modified example of an in-vehicle communication system according to an embodiment of the present disclosure. Contents other than those described below are the same as those of the in-vehicle communication system 301 shown in FIG.

[0087] 6, the second modification of the in-vehicle communication system 301 includes an optical coupler 3, a plurality of optical fibers 91, and a plurality of in-vehicle devices 101.

[0088] In the example shown in FIG. 6, the in-vehicle communication system 301 includes, as the in-vehicle device 101, ECU1 to ECU5.

[0089] In the optical coupler 3, an optical transmission path 11 between specific on-board devices 101 among a combination of a plurality of on-board devices 101 connected to the optical coupler 3 is selectively provided. That is, in the optical coupler 3, an optical transmission path 11 corresponding to a specific pair of on-board devices 101 is selectively provided.

[0090] 6, in the optical coupler 3, the optical transmission path is branched, so that some sets of the on-vehicle devices 101 in the on-vehicle communication system 301 are connected using the optical transmission path 11. More specifically, the optical coupler 3 includes an optical transmission path 11 connected between ECU1 and ECU2, an optical transmission path 11 connected between ECU1 and ECU3, an optical transmission path 11 connected between ECU1 and ECU4, an optical transmission path 11 connected between ECU1 and ECU5, an optical transmission path 11 connected between ECU2 and ECU3, and an optical transmission path 11 connected between ECU4 and ECU5.

[0091] For example, in the second modification, information transmission between the ECU 2 and the ECUs 4 and 5 is not required, and information transmission between the ECU 3 and the ECUs 4 and 5 is not required. For this reason, in the optical coupler 3, the optical transmission path connecting the ECU 2 and the ECUs 4 and 5 is excluded, and the optical transmission path connecting the ECU 3 and the ECUs 4 and 5 is excluded.

[0092] In this example, the ECU 1 that transmits the synchronization information is connected to the ECUs 2 to 5. That is, at least one of the multiple in-vehicle devices 101 in the in-vehicle communication system 301 is connected to all the other in-vehicle devices 101 via the optical coupler 1 and the optical fiber 91.

[0093] FIG. 7 is a diagram showing an example of information transmission timing in the second modification of the in-vehicle communication system according to the embodiment of the present disclosure.

[0094] 7, in the second modification of the in-vehicle communication system 301, a pair of in-vehicle devices 101 that does not collide with other pairs of optical signals is allowed to transmit information at the same timing, that is, in the same time slot.

[0095] Specifically, since no collision occurs when Ethernet frames are transmitted simultaneously between ECU2 and ECU3 and between ECU4 and ECU5, transmission of Ethernet frames in the same time slot is permitted.

[0096] 7, the communication frame includes five time slots TS1 to TS5. The time slots TS1 to TS5 are assigned to ECU1 to ECU5, respectively.

[0097] In time slot TS2 of a certain communication frame, an Ethernet frame is transmitted from ECU2 to ECU3 and from ECU4 to ECU5. In time slot TS5 of the next communication frame, an Ethernet frame is transmitted from ECU5 to ECU4 and from ECU2 to ECU3.

[0098] For example, if ECU2 is a sensor, ECU3 is an autonomous driving ECU, and ECU4 and ECU5 are ECUs that provide entertainment services, and communication between ECU2, 3 and ECU4, 5 is not required, the data communication capacity in the in-vehicle network can be increased by forming an optical transmission path 11 such as an optical coupler 3.

[0099] [Variation 3] 8 is a diagram showing a configuration of a third modified example of an in-vehicle communication system according to an embodiment of the present disclosure. Contents other than those described below are the same as those of the in-vehicle communication system 301 shown in FIG.

[0100] 8, the third modification of the in-vehicle communication system 301 includes an optical coupler 4, a plurality of optical fibers 91, and a plurality of in-vehicle devices 101. The optical coupler 4 includes an optical fiber 91 and a plurality of in-vehicle devices 101.

[0101] The optical coupler 4 includes a plurality of optical transmission paths 11 which are branched at the optical coupler 4 and connected to a common on-vehicle device 101 via corresponding optical fibers 91, respectively.

[0102] More specifically, the in-vehicle device 101 which is the ECU 1 includes a communication unit 55, connection units 52 and 54, and a storage unit 53.

[0103] In the example shown in FIG. 8, in the optical coupler 4, the optical transmission path at the input / output portion with the ECU 1 branches, and each branch is connected to the ECU 1 via an optical fiber 91.

[0104] In the ECU 1, the connection portions 52 and can connect optical fibers 91. The two optical fibers 91 are connected to the in-vehicle device 101 at the connection portions 52 and by means of connectors, adhesive, or the like.

[0105] The communication unit 55 includes optical transceivers 61 and 62, and similarly to the communication unit 51, communicates with other in-vehicle devices 101 by transmitting and receiving optical signals including Ethernet frames via the optical coupler 4 and the optical fiber 91. The optical transceivers 61 and 62 are connected to the corresponding optical fibers 91 via the connection units 52 and 54, respectively.

[0106] In normal operation, the ECU 1 communicates with each ECU using the optical transceiver 61, and keeps the optical transceiver 62 on standby. If the optical transceiver 61 fails, the ECU 1 operates the optical transceiver 62 and communicates with each ECU using the optical transceiver 62. This optical transceiver switching may be performed autonomously by the ECU 1, or may be performed manually.

[0107] For example, it is particularly effective to apply this type of redundancy to an ECU of high importance, such as an autonomous driving ECU, or an ECU installed in a location in the vehicle 401 where the environmental load, such as temperature, is high.

[0108] That is, in variant example 3 of the in-vehicle communication system 301, for example, the connection relationship of each in-vehicle device 101 in the in-vehicle network of the vehicle 401 is fixed, and the communication relationship, i.e., the relationship for exchanging information, of each in-vehicle device 101 is fixed. Taking this into consideration, the optical coupler 4 is designed according to the type of in-vehicle device 101.

[0109] [Variation 4] 9 is a diagram showing a configuration of a fourth modified example of an in-vehicle communication system according to an embodiment of the present disclosure. Contents other than those described below are the same as those of the in-vehicle communication system 301 shown in FIG.

[0110] 9, the fourth modification of the in-vehicle communication system 301 includes an optical coupler 5, a plurality of optical fibers 91, and a plurality of in-vehicle devices 101.

[0111] The optical coupler 5 includes a plurality of optical transmission paths 11 that are branched at the optical coupler 5 and connected to a plurality of in-vehicle devices 101 via corresponding optical fibers 91, and are set to have different branching ratios. Here, the branching ratio is the ratio of the optical power of each output port to the total optical power of all output ports in the optical coupler.

[0112] In the optical coupler 5, for example, a branching ratio to a specific in-vehicle device 101 is set high. The branching ratio can be set by, for example, adjusting the thickness of the optical waveguide or adjusting the length and diameter of the fused extension portion of each optical fiber.

[0113] FIG. 10 is a diagram illustrating an example of the branching ratio of each optical transmission line in the fourth modification of the in-vehicle communication system according to the embodiment of the present disclosure.

[0114] 10, in optical coupler 5, the branching ratio to ECU 1, which is in-vehicle device 101 that transmits synchronization information, is set high.

[0115] That is, in optical coupler 5, the branching ratios from ECU 1, the output source, to the output destinations ECUs 2 to 4 are each 33.3%, the branching ratios from ECU 2, the output source, to the output destinations ECUs 1, 3, and 4 are respectively 50%, 25%, and 25%, the branching ratios from ECU 3, the output source, to the output destinations ECUs 1, 2, and 4 are respectively 50%, 25%, and 25%, and the branching ratios from ECU 4, the output source, to the output destinations ECUs 1, 2, and 3 are respectively 50%, 25%, and 25%.

[0116] This makes it possible to reduce the bit error rate of Ethernet frames transmitted from a specific in-vehicle device 101, here ECU 1, to each ECU. Here, the bit error rate means a value that expresses the frequency of errors in determining that 1 is zero and errors in determining that 0 is 1, as a percentage.

[0117] In addition to the ECU1 that transmits synchronization information, by setting a high branching ratio for ECUs of high importance, such as an autonomous driving ECU, or ECUs installed in locations of vehicle 401 that are subject to high environmental loads, such as high temperature, in addition to the ECU1 that transmits synchronization information, the reliability of vehicle 401 is improved, which is particularly effective.

[0118] That is, in variant example 4 of the in-vehicle communication system 301, for example, the connection relationship of each in-vehicle device 101 in the in-vehicle network of the vehicle 401 is fixed, and the communication relationship, i.e., the relationship for exchanging information, of each in-vehicle device 101 is fixed. With this in mind, the optical coupler 5 is designed according to the type of in-vehicle device 101.

[0119] [Variation 5] 11 is a diagram showing the configuration of a fifth modified example of an in-vehicle communication system according to an embodiment of the present disclosure, which is similar to the in-vehicle communication system 301 shown in FIG.

[0120] 11, the fifth modification of the in-vehicle communication system 301 includes an optical coupler 6, a plurality of optical fibers 91, and a plurality of in-vehicle devices 101. The optical coupler 6 includes an optical fiber 91 and a plurality of in-vehicle devices 101.

[0121] In the optical coupler 6, an optical transmission path 11 between specific on-vehicle devices 101 among a combination of a plurality of on-vehicle devices 101 connected to the optical coupler 6 is selectively provided. That is, in the optical coupler 6, an optical transmission path 11 corresponding to a specific pair of on-vehicle devices 101 is selectively provided.

[0122] 11, the optical transmission path is branched in the optical coupler 6, so that some sets of the on-vehicle devices 101 in the on-vehicle communication system 301 are connected using the optical transmission path 11. More specifically, the optical coupler 6 includes an optical transmission path 11 connected between ECU1 and ECU2, an optical transmission path 11 connected between ECU1 and ECU3, and an optical transmission path 11 connected between ECU1 and ECU4.

[0123] For example, in the fifth modification, there is no need to transmit information between the ECUs 2 and 4. For this reason, in the optical coupler 6, the optical transmission path connecting the ECUs 2 and 4 is excluded.

[0124] In this example, the ECU 1 that transmits the synchronization information is connected to the ECUs 2 to 4. That is, at least one of the multiple in-vehicle devices 101 in the in-vehicle communication system 301 is connected to all the other in-vehicle devices 101 via the optical coupler 1 and the optical fiber 91.

[0125] In the fifth modification, the ECU1 always receives information addressed to the ECU1, and therefore destination information is not necessarily required in information transmission from the ECU2 to ECU4 to the ECU1.

[0126] In addition, in the fifth modification, since there is no loss due to branching of the transmission path in the transmission of the optical signal from the ECU2 to ECU4 to the ECU1, the required optical output power of the optical transceivers in the ECU2 to ECU4 is relaxed. This allows the use of relatively low-performance and inexpensive optical transceivers, thereby reducing costs. For example, the configuration of the fifth modification is particularly effective in a case where the ECU2 to ECU4 are sensors and the ECU1 is an ADAS (Advanced Driver Assistance System) ECU that performs processing based on the measurement results of the sensors.

[0127] That is, in variant example 5 of the in-vehicle communication system 301, for example, the connection relationship of each in-vehicle device 101 in the in-vehicle network of the vehicle 401 is fixed, and the communication relationship, i.e., the relationship for exchanging information, of each in-vehicle device 101 is fixed. Taking this into consideration, the optical coupler 6 is designed according to the type of in-vehicle device 101.

[0128] In addition, the communication unit 51 in the in-vehicle device 101 may be configured to be capable of communicating with multiple other in-vehicle devices 101 via an optical coupler, and to be capable of relaying information received from another in-vehicle device 101 to another in-vehicle device 101 via the optical coupler.

[0129] For example, the fifth modification may have the following configuration. That is, in the fifth modification, the communication unit 51 in the ECU 1 receives an optical signal in the optical transceiver 61 via the optical coupler 6 and the optical fiber 91, and acquires an Ethernet frame included in the received optical signal. The communication unit 51 checks the destination MAC address of the Ethernet frame, and if the destination MAC address is the MAC address of another ECU, generates an optical signal including the Ethernet frame and transmits it to the other ECU via the optical fiber 91 and the optical coupler 6.

[0130] With this configuration, the ECUs 2 to 4 can transmit Ethernet frames to other ECUs via the ECU 1. That is, in the in-vehicle communication system 301, the ECU 1 can realize relay processing between the ECUs 2 to 4 with a simple configuration including one optical transceiver 61.

[0131] Furthermore, the in-vehicle communication system 301 may be configured to include a plurality of master in-vehicle devices that transmit synchronization information.

[0132] For example, the fifth modification may have the following configuration: That is, in the fifth modification, the in-vehicle communication system 301 further includes an ECU 10 (not shown) that transmits synchronization information.

[0133] 11, the optical coupler 6 further includes an optical transmission path 11 connected between the ECU 10 and the ECU 2, an optical transmission path 11 connected between the ECU 10 and the ECU 3, and an optical transmission path 11 connected between the ECU 10 and the ECU 4. That is, the ECU 10 that transmits the synchronization information is connected to the ECUs 2 to 4.

[0134] In the in-vehicle communication system 301, the ECUs 1 to 4 transmit information at timings according to the synchronization information received from the ECU 10, thereby performing time division multiplexing communication. More specifically, the ECU 10 transmits information at timings according to the synchronization information generated by the ECU 10. The ECUs 2 to 4 transmit information at timings according to the synchronization information received from the ECU 10.

[0135] In the in-vehicle communication system according to the embodiment of the present disclosure, the in-vehicle devices 101 are configured to perform two-way communication with each other, but this is not limited thereto. Some or all of the multiple in-vehicle devices in the in-vehicle communication system 301 may be configured to perform one-way communication.

[0136] In addition, in the in-vehicle communication system according to the embodiment of the present disclosure, each in-vehicle device 101 other than the master in-vehicle device transmits information at a timing according to the synchronization information received from the master in-vehicle device, thereby performing time division multiplexing communication, but this is not limited thereto. Each in-vehicle device 101 may receive synchronization information from a device other than the in-vehicle device 101.

[0137] In addition, although the in-vehicle communication system according to the embodiment of the present disclosure is configured to perform time division multiplexing communication, the present disclosure is not limited to this. For example, each in-vehicle device 101 may be configured to perform information retransmission control without performing time division multiplexing communication.

[0138] In addition, in the in-vehicle communication system according to the embodiment of the present disclosure, at least one of the multiple in-vehicle devices 101 is configured to be connected to all the other in-vehicle devices 101 via optical couplers, but this is not limited to the above. For example, if each in-vehicle device 101 is configured to perform information retransmission control as described above, transmission of synchronization information becomes unnecessary, so that the configuration may be such that there is no in-vehicle device 101 that is connected to all the other in-vehicle devices 101 via optical couplers.

[0139] 1, the in-vehicle communication system according to the embodiment of the present disclosure is configured to include four in-vehicle devices 101 and an optical coupler 1, but is not limited to this. The in-vehicle communication system can achieve the object of the present invention, which is to build an excellent system for communication between in-vehicle devices, with a minimum configuration including three in-vehicle devices 101 and an optical coupler including two optical transmission paths that respectively connect one in-vehicle device 101 to the other two in-vehicle devices 101.

[0140] Specifically, the optical coupler is used in an in-vehicle communication system 301 including a first in-vehicle device 101, a second in-vehicle device 101, and a third in-vehicle device 101. The optical coupler includes a first optical transmission path 11 connecting the first in-vehicle device 101 and the second in-vehicle device 101, and a second optical transmission path 11 connecting the first in-vehicle device 101 and the third in-vehicle device 101.

[0141] Meanwhile, there is a demand for a technology that goes beyond the technology described in Patent Document 1 and enables construction of an excellent system for performing communication between in-vehicle devices.

[0142] For example, in a configuration in which electrical communication is performed between in-vehicle devices using a switch device, the ECU, which is the switch device, requires components such as a transceiver and a communication IC (Integrated Circuit), as well as a control circuit such as a CPU (Central Processing Unit) that controls these components, which often results in high costs, large size, and weight. In addition, the cables that transmit electrical signals use metal conductors, which are heavy and increase the weight of the vehicle. In addition, in order to deal with the increase in communication volume in in-vehicle networks, the adoption of high-speed communication capable of transmitting large volumes of data is progressing, which causes problems with deterioration of characteristics such as EMC (electro-magnetic compatibility) and transmission distance.

[0143] In contrast, in the in-vehicle communication system according to the embodiment of the present disclosure, the optical couplers 1-5 include a plurality of optical transmission paths 11. The plurality of in-vehicle devices 101 are capable of communicating with each other via the optical couplers 1-5.

[0144] In this way, the configuration in which communication between on-board devices 101 is performed using optical couplers including a plurality of optical transmission paths 11 makes it possible to simplify communication control by eliminating the need for switch processing, reduce the use of active elements, and reduce the weight of the transmission paths, compared to a configuration in which electrical communication is performed between on-board devices 101 using a switch device, thereby realizing low-cost, small-sized, lightweight, etc. of the on-board network. Also, for example, characteristics such as EMC and transmission distance can be improved.

[0145] Therefore, in the in-vehicle communication system according to the embodiment of the present disclosure, an excellent system for communication between in-vehicle devices can be constructed.

[0146] Moreover, in the in-vehicle communication system according to the embodiment of the present disclosure, the multiple in-vehicle devices 101 include at least one master in-vehicle device which is an in-vehicle device 101 that transmits synchronization information for synchronizing the transmission timing of each of the multiple in-vehicle devices 101. Time division multiplexing communication is performed by each in-vehicle device 101 other than the master in-vehicle device transmitting information based on the synchronization information received from the master in-vehicle device.

[0147] With this configuration, communications between the in-vehicle devices 101 can be smoothly performed with simple processing.

[0148] In addition, in the in-vehicle communication system according to the embodiment of the present disclosure, at least one of the multiple in-vehicle devices 101 is connected to all other in-vehicle devices 101 with which it can communicate via the optical couplers 1-5.

[0149] With this configuration, timing control for time-division communication of each on-vehicle device 101 can be performed using an optical coupler, so that the configuration of the transmission path between each on-vehicle device 101 can be simplified.

[0150] In addition, in the in-vehicle communication system according to the embodiment of the present disclosure, the optical coupler 2 further includes a diagnostic optical transmission path 12 that connects between the optical transmission path 11 between the in-vehicle devices 101 and the light receiving circuit 71 outside the optical coupler 2, and detects the state of the optical coupler 2.

[0151] With this configuration, for example, compared to a configuration in which electrical communication is performed using a switch device between in-vehicle devices 101, in a transmission line configuration using optical couplers, where there is a relatively high need to monitor deterioration such as characteristics at branch points of the transmission line, it is possible to effectively diagnose deterioration over time, etc.

[0152] In addition, in the in-vehicle communication system according to the embodiment of the present disclosure, the optical coupler 3 selectively provides an optical transmission path 11 between specific in-vehicle devices 101 among combinations of a plurality of in-vehicle devices 101 connected to the optical coupler 3.

[0153] With this configuration, in an in-vehicle network in which the communication relationship between each in-vehicle device 101 is fixed, unnecessary optical transmission paths can be eliminated in the optical coupler, enabling parallel transmission of information, thereby increasing the data communication capacity in the in-vehicle network.

[0154] In addition, in the in-vehicle communication system according to the embodiment of the present disclosure, the optical coupler 4 includes a plurality of optical transmission paths 11 that are branched at the optical coupler 4 and connected to a common in-vehicle device 101 .

[0155] With this configuration, with a simple configuration using the branching of the optical transmission line 11 in the optical coupler 4, it is possible to realize redundancy of the communication section of the in-vehicle device 101 and redundancy of the communication path.

[0156] In addition, in the in-vehicle communication system according to the embodiment of the present disclosure, the optical coupler 5 includes a plurality of optical transmission paths 11 that are branched at the optical coupler 5 and connected to a plurality of in-vehicle devices 101, respectively, and are set to have different branching ratios.

[0157] With this configuration, the stability of communication can be set for each in-vehicle device 101 in a simple manner by designing the optical transmission path 11 in the optical coupler 5, thereby improving the reliability of communication in the in-vehicle network.

[0158] In the in-vehicle communication system according to the embodiment of the present disclosure, the synchronization information defines a communication frame including a plurality of time slots. The master in-vehicle device assigns time slots to each in-vehicle device 101 in the synchronization information such that the time slots are switched at a timing when each in-vehicle device 101 does not transmit a packet such as an Ethernet frame.

[0159] With this configuration, it is possible to prevent a situation in which a packet is divided and transmitted from the in-vehicle device 101 across communication frames, resulting in the inability of the receiving in-vehicle device 101 to receive the packet, and it is possible to carry out each communication between the in-vehicle devices 101 smoothly with simple processing.

[0160] Moreover, the optical coupler according to the embodiment of the present disclosure is used in an in-vehicle communication system 301 including a first in-vehicle device 101, a second in-vehicle device 101, and a third in-vehicle device 101. The optical coupler includes at least a first optical transmission path 11 connecting the first in-vehicle device 101 and the second in-vehicle device 101, and a second optical transmission path 11 connecting the first in-vehicle device 101 and the third in-vehicle device 101.

[0161] In this way, the configuration in which communication between on-board devices 101 is performed using optical couplers including a plurality of optical transmission paths 11 makes it possible to simplify communication control by eliminating the need for switch processing, reduce the use of active elements, and reduce the weight of the transmission paths, compared to a configuration in which electrical communication is performed between on-board devices 101 using a switch device, thereby realizing low-cost, small-sized, lightweight, etc. of the on-board network. Also, for example, characteristics such as EMC and transmission distance can be improved.

[0162] Therefore, the optical coupler according to the embodiment of the present disclosure can configure an excellent system for communication between in-vehicle devices.

[0163] In addition, in the in-vehicle device according to the embodiment of the present disclosure, the communication unit 51 communicates with other in-vehicle devices 101 via optical couplers 1-5 including a plurality of optical transmission paths 11. The connection unit 52 is capable of connecting an optical fiber 91 connected to the optical transmission path 11.

[0164] In this way, the configuration in which communication between on-board devices 101 is performed using optical couplers including a plurality of optical transmission paths 11 makes it possible to simplify communication control by eliminating the need for switch processing, reduce the use of active elements, and reduce the weight of the transmission paths, compared to a configuration in which electrical communication is performed between on-board devices 101 using a switch device, thereby realizing low-cost, small-sized, lightweight, etc. of the on-board network. Also, for example, characteristics such as EMC and transmission distance can be improved.

[0165] Therefore, the in-vehicle device according to the embodiment of the present disclosure can configure an excellent system for communication between in-vehicle devices.

[0166] In addition, in the in-vehicle device according to the embodiment of the present disclosure, the communication unit 51 is capable of communicating with multiple other in-vehicle devices 101 via an optical coupler, and is capable of relaying information received from the other in-vehicle devices 101 to other in-vehicle devices 101 other than the other in-vehicle devices 101 via the optical coupler.

[0167] With this configuration, for example, the vehicle-mounted device 101 can realize relay processing between other vehicle-mounted devices 101 with a simple configuration including one optical transceiver.

[0168] It is also possible to combine some or all of the components and operations of each example of the in-vehicle communication system according to the embodiment of the present disclosure as appropriate.

[0169] The above-described embodiments should be considered as illustrative and not restrictive in all respects. The scope of the present invention is defined by the claims, not the above description, and is intended to include all modifications within the meaning and scope of the claims.

[0170] The above description includes the following additional features. [Appendix 1] An in-vehicle communication system, an optical coupler including a plurality of optical transmission paths; a plurality of in-vehicle devices capable of communicating with each other via the optical coupler; the optical transmission path is an optical waveguide, An in-vehicle communication system, wherein the optical coupler is designed according to the type of the in-vehicle device.

[0171] [Appendix 2] An optical coupler for use in an in-vehicle communication system including a first in-vehicle device, a second in-vehicle device, and a third in-vehicle device, a first optical transmission line connecting the first in-vehicle device and the second in-vehicle device; a second optical transmission line connecting the first in-vehicle device and the third in-vehicle device; the optical transmission path is an optical waveguide, The optical coupler is designed according to the type of the in-vehicle device.

[0172] [Appendix 3] An in-vehicle device in an in-vehicle communication system including an optical coupler including a plurality of optical transmission paths, a communication unit that communicates with another in-vehicle device via the optical coupler; a connection portion capable of connecting an optical fiber to be connected to the optical transmission line, the optical transmission path is an optical waveguide, The optical coupler is designed according to the type of the in-vehicle device. [Explanation of symbols]

[0173] 1~6 Optical coupler 11,12 Optical transmission line 51,55 Communications Department 52,54 Connection 53 Storage section 61,62 Optical Transceiver 71 Photoreceiving circuit 91,92 Optical fiber 101 In-vehicle equipment 151 Diagnostic Circuits 301 In-vehicle communication system 401 vehicles

Claims

1. an optical coupler including a plurality of first optical transmission lines; a plurality of on-board devices capable of communicating with each other via the first optical transmission path included in the optical coupler; the plurality of in-vehicle devices include at least one master in-vehicle device that transmits synchronization information for synchronizing transmission timings of the plurality of in-vehicle devices via the first optical transmission path; An in-vehicle communication system, in which time division multiplexing communication is performed by each of the in-vehicle devices other than the master in-vehicle device transmitting information based on the synchronization information received from the master in-vehicle device via the first optical transmission path.

2. The in-vehicle communication system according to claim 1 , wherein at least one of the plurality of in-vehicle devices is connected to all of the other in-vehicle devices via the first optical transmission path included in the optical coupler.

3. the optical coupler further includes a second optical transmission line connecting the first optical transmission line and an optical receiving circuit external to the optical coupler; The in-vehicle communication system further comprises:

3. The in-vehicle communication system according to claim 1, further comprising a diagnostic circuit that measures an intensity of an optical signal received via the second optical transmission line using the light receiving circuit and detects a state of the optical coupler based on a measurement result.

4. the first optical transmission line is selectively provided in the optical coupler to connect specific combinations of the in-vehicle devices to each other among the combinations of the in-vehicle devices connected to the optical coupler; 4. The in-vehicle communication system according to claim 1, wherein packets are permitted to be transmitted in parallel from two other in-vehicle devices different from the in-vehicle devices of the pair not provided with the first optical transmission path to each of the in-vehicle devices of the pair.

5. 5. The in-vehicle communication system according to claim 1, wherein at least one of the plurality of first optical transmission paths is branched at the optical coupler, and the branched plurality of optical transmission paths are connected to one common in-vehicle device.

6. 6. The in-vehicle communication system according to claim 1, wherein the optical coupler includes a plurality of the first optical transmission paths that are branched in the optical coupler and connected to the plurality of in-vehicle devices, respectively, and are set so that a branching ratio to the in-vehicle device that transmits the synchronization information is high.

7. the synchronization information defines a communication frame including a plurality of time slots; 7. The in-vehicle communication system according to claim 1, wherein the master in-vehicle device assigns the time slots to the in-vehicle devices in the synchronization information such that the time slots are switched at timings when the in-vehicle devices do not transmit packets.

8. An optical coupler for use in an in-vehicle communication system including a first in-vehicle device, a second in-vehicle device, and a third in-vehicle device, a first optical transmission line connecting the first in-vehicle device and the second in-vehicle device; a second optical transmission line connecting the first in-vehicle device and the third in-vehicle device; An optical coupler, in which the first optical transmission path branches at the optical coupler, and the branched multiple optical transmission paths are connected to a single common in-vehicle device, which is the first in-vehicle device or the second in-vehicle device.

9. An in-vehicle device in an in-vehicle communication system including an optical coupler including a plurality of optical transmission paths, a communication unit that communicates with another in-vehicle device via the optical transmission path included in the optical coupler; a connection portion capable of connecting an optical fiber to be connected to the optical transmission line, The communication unit transmits or receives, via the optical transmission path, synchronization information for synchronizing transmission timings of each of a plurality of on-board devices in the on-board communication system.

10. The in-vehicle device according to claim 9, wherein the communication unit is capable of communicating with a plurality of other in-vehicle devices via the optical transmission path included in the optical coupler, and is capable of relaying information received from the other in-vehicle devices to the other in-vehicle devices other than the other in-vehicle devices via the optical transmission path included in the optical coupler.

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