Optical communication system, optical communication method, and optical transmitter

Abstract

This system aims to create an optical communication system that reduces the possibility of signal light entering the worker's eyes. [Solution] The optical communication system (1) includes an optical communication path (11), an electrical communication path (12), an optical receiver (14) optically connected to one end of the optical communication path (11) and electrically connected to one end of the electrical communication path (12), and an optical transmitter (13) optically connected to the other end of the optical communication path (11) and electrically connected to the other end of the electrical communication path (12). The optical transmitter (13) receives a control signal from the optical receiver (14) via the electrical communication path (12) indicating the reception state of the optical signal in the optical receiver (14), and transmits a data signal, which is an optical signal, to the optical receiver (14) via the optical communication path (11) only if the control signal indicates a reception state that matches the transmission state of the optical signal in the optical transmitter (13).

Description

Technical Field

[0001] The present disclosure relates to an optical communication system realized by optically connecting an optical transmitter and an optical receiver via an optical communication path and electrically connecting them via an electrical communication path. The present disclosure also relates to an optical communication method in such an optical communication system and an optical transmitter included in such an optical communication system.

Background Art

[0002] Optical communication systems that transmit data signals using optical communication paths such as optical fibers are widely used. For example, Patent Document 1 discloses a data transmission device in which a camera-side connector and a processing device-side connector are optically connected using an optical fiber and electrically connected using a differential line.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In an optical communication system in which an optical transmitter and an optical receiver are optically connected using an optical communication path and electrically connected using an electrical communication path, such as the data transmission device described in Patent Document 1, a data signal that is an optical signal is transmitted via the optical communication path, and a control signal that is an electrical signal is transmitted via the electrical communication path.

[0005] In such optical communication systems, optical connectors may be provided at both ends or in the middle of the optical communication path, and electrical connectors may be provided at both ends or in the middle of the electrical communication path. If an operator unplugs an optical connector while a data signal is being transmitted, the signal light may enter the operator's eyes. To prevent this, the optical receiver is equipped with a function that, upon detecting an interruption in the data signal, transmits a Loss of Signal (LOS) signal to the optical transmitter via the electrical communication path. The optical transmitter is also equipped with a function that, upon detecting the LOS signal, stops or interrupts the transmission of the data signal via the optical communication path. This provides an eye-safety function, reducing the possibility of the signal light entering the operator's eyes.

[0006] However, the eye safety function using the LOS signal is effective if the optical connector is disconnected after data signal transmission has started, but it is ineffective if the optical connector is disconnected before data signal transmission has started. Therefore, there remains a risk that the signal light may enter the operator's eyes when data signal transmission begins.

[0007] This disclosure has been made in view of the above-mentioned problems, and one of its purposes is to realize an optical communication system that reduces the possibility of signal light entering the worker's eyes. [Means for solving the problem]

[0008] An optical communication system according to one aspect of the present invention includes an optical communication path, an electrical communication path, an optical receiver optically connected to one end of the optical communication path and electrically connected to one end of the electrical communication path, and an optical transmitter optically connected to the other end of the optical communication path and electrically connected to the other end of the electrical communication path, wherein the optical receiver transmits a control signal indicating the reception state of an optical signal in the optical receiver to the optical transmitter via the electrical communication path, and the optical transmitter receives the control signal from the optical receiver via the electrical communication path and starts or continues a data signal transmission process that transmits a data signal, which is an optical signal, to the optical receiver via the optical communication path only if the control signal indicates a reception state that matches the transmission state of an optical signal in the optical transmitter. [Effects of the Invention]

[0009] According to one aspect of this disclosure, an optical communication system can be realized that reduces the possibility of signal light entering the worker's eyes. [Brief explanation of the drawing]

[0010] [Figure 1] This is a block diagram showing the configuration of an optical communication system related to one embodiment of the present invention. [Figure 2] Figure 1 is a block diagram showing a specific example of an optical communication system. [Figure 3] Figure 1 is a flowchart showing the operation (first half) of an optical transmitter included in the optical communication system. [Figure 4] This flowchart shows the operation (middle stage) of an optical transmitter included in the optical communication system shown in Figure 1, following the operation (first half) shown in Figure 3. [Figure 5] This flowchart shows the operation (second half) of an optical transmitter included in the optical communication system shown in Figure 1, following the operation (middle) shown in Figure 4. [Figure 6] This is a cross-sectional view of a composite cable containing optical and telecommunication channels, which is included in the optical communication system shown in Figure 1. [Modes for carrying out the invention]

[0011] (Configuration of the optical communication system) The configuration of the optical communication system 1 according to one embodiment of the present invention will be described with reference to Figure 1. Figure 1 is a block diagram showing the configuration of the optical communication system 1.

[0012] As shown in Figure 1, the optical communication system 1 includes an optical communication channel 11, an electrical communication channel 12, an optical transmitter 13, and an optical receiver 14.

[0013] The optical communication channel 11 is a communication channel for transmitting optical signals. For example, the optical communication channel 11 is an optical fiber. The optical communication channel 11 may be housed in an optical cable, or it may be housed in a composite cable together with the telecommunication channel 12. The telecommunication channel 12 is a communication channel for transmitting electrical signals. For example, the telecommunication channel 12 is a metal wire. The telecommunication channel 12 may be housed in an electrical cable, or it may be housed in a composite cable together with the optical communication channel 11.

[0014] An optical transmitter 13 is optically connected to one end of the optical communication path 11. The optical connection between the optical communication path 11 and the optical transmitter 13 is achieved, for example, by mating an optical connector 11a provided at one end of the optical communication path 11 with an optical connector 131 provided on the optical transmitter 13. An optical receiver 14 is optically connected to the other end of the optical communication path 11. The optical connection between the optical communication path 11 and the optical receiver 14 is achieved, for example, by mating an optical connector 11b provided at the other end of the optical communication path 11 with an optical connector 141 provided on the optical receiver 14.

[0015] The optical communication path 11 may be divided into a first section Ia on the optical transmitter 13 side and a second section Ib on the optical receiver 14 side. In this case, the optical connection between the first section Ia and the second section Ib is achieved by mating an optical connector 11c provided at one end of the first section Ia (the end opposite to the optical connector 11a side) with an optical connector 11d provided at one end of the second section Ib (the end opposite to the optical connector 11b side).

[0016] One end of the electrical communication line 12 is electrically connected to an optical transmitter 13. The electrical connection between the electrical communication line 12 and the optical transmitter 13 is realized, for example, by fitting an electrical connector 12a provided at one end of the electrical communication line 12 and an electrical connector 132 provided on the optical transmitter 13. Also, an optical receiver 14 is electrically connected to the other end of the electrical communication line 12. The electrical connection between the electrical communication line 12 and the optical receiver 14 is realized, for example, by fitting an electrical connector 12b provided at the other end of the electrical communication line 12 and an electrical connector 142 provided on the optical receiver 14.

[0017] The electrical communication line 12 may be divided into a first section Ja on the optical transmitter 13 side and a second section Jb on the optical receiver 14 side. In this case, the electrical connection between the first section Ja and the second section Jb is realized by fitting an electrical connector 12c provided at one end of the first section Ja (the end opposite to the electrical connector 12a side) and an electrical connector 12d provided at one end of the second section Jb (the end opposite to the electrical connector 12b side).

[0018] As shown in FIG. 1, the optical communication system 1 further includes an electrical communication line 15 and a monitor device 16.

[0019] One end of the electrical communication line 15 is electrically connected to the optical transmitter 13. The electrical connection between the electrical communication line 15 and the optical transmitter 13 is realized, for example, by fitting an electrical connector 15a provided at one end of the electrical communication line 15 and an electrical connector 136 provided on the optical transmitter 13. Also, the monitor device 16 is electrically connected to the other end of the electrical communication line 15. The electrical connection between the electrical communication line 15 and the monitor device 16 is realized, for example, by fitting an electrical connector 15b provided at the other end of the electrical communication line 15 and an electrical connector 161 provided on the monitor device 16.

[0020] (Configuration of the optical transmitter) The configuration of the optical transmitter 13 will be described below with continued reference to FIG. 1.

[0021] As shown in Figure 1, the optical transmitter 13 comprises an optical signal transmission unit 133, an electrical signal communication unit 134, and a control unit 135.

[0022] The optical signal transmitting unit 133 is configured to transmit an optical signal to the optical receiver 14 via the optical communication channel 11. The optical signal transmitting unit 133 can be implemented, for example, by a known optical modulation circuit. The optical signal transmitting unit 133 performs test signal transmission processing and data signal transmission processing. Test signal transmission processing is the process of transmitting a test signal, which is an optical signal, to the optical receiver 14 via the optical communication channel 11. Data signal transmission processing is the process of transmitting a data signal, which is an optical signal, to the optical receiver 14 via the optical communication channel 11.

[0023] The optical signal transmission unit 133 has two switchable states, namely a prohibited state and an permitted state. The prohibited state is a state in which the transmission of optical signals is prohibited. On the other hand, the permitted state is a state in which the transmission of optical signals is permitted. Test signal transmission processing and data signal transmission processing can only be performed in the permitted state.

[0024] Furthermore, the optical signal transmission unit 133 provides the control unit 135 with an electrical signal representing the transmission status of the optical signal in the optical transmitter 13 (hereinafter also referred to as the "transmission status signal"). In this embodiment, the transmission status of the optical signal in the optical transmitter 13 is equivalent to the transmission status of the optical signal in the optical signal transmission unit 133. When the optical signal transmission unit 133 is not transmitting an optical signal, it provides the control unit 135 with a transmission status signal indicating a no-signal state. When the optical signal transmission unit 133 is transmitting an optical signal, it provides the control unit 135 with a transmission status signal indicating the intensity of the optical signal being transmitted.

[0025] The electrical signal communication unit 134 is configured to receive electrical signals from the optical receiver 14 via the telecommunication channel 12 and to transmit electrical signals to the monitoring device 16 via the telecommunication channel 15. The electrical signal communication unit 134 can be implemented, for example, by a known electrical demodulation circuit. Examples of electrical signals that the electrical signal communication unit 134 receives from the optical receiver 14 via the telecommunication channel 12 include control signals, which will be described later. Examples of electrical signals that the electrical signal communication unit 134 transmits to the monitoring device 16 via the telecommunication channel 15 include alert signals, which will be described later.

[0026] The electrical signal communication unit 134 provides the control unit 135 with the control signal received from the optical receiver 14 via the telecommunication channel 12. The control unit 135 switches the state of the optical signal transmission unit 133 by referring to the transmission status signal obtained from the optical signal transmission unit 133 and the control signal obtained from the electrical signal communication unit 134. The control unit 135 can be implemented, for example, by a known microcontroller.

[0027] In this embodiment, the control unit 135 switches the state of the optical signal transmission unit 133 using the TxDisable signal. Here, the TxDisable signal is a binary signal that takes the value of High or Low. The optical signal transmission unit 133 can transmit an optical signal when the value of the TxDisable signal is Low, and cannot transmit an optical signal when the value of the TxDisable signal is High. Therefore, the control unit 135 switches the state of the optical signal transmission unit 133 from a prohibited state to an permitted state by changing the value of the TxDisable signal from High to Low. Also, the control unit 135 switches the state of the optical signal transmission unit 133 from a permitted state to a prohibited state by changing the value of the TxDisable signal from Low to High.

[0028] (Configuration of the optical receiver) The configuration of the optical receiver 14 will be explained further with reference to Figure 1.

[0029] As shown in Figure 1, the optical receiver 14 comprises an optical signal receiving unit 143, an electrical signal communication unit 144, and a control unit 145.

[0030] The optical signal receiving unit 143 is configured to receive optical signals from the optical transmitter 13 via the optical communication path 11. The optical signal receiving unit 143 can be implemented, for example, by a known optical demodulation circuit. The optical signals received by the optical signal receiving unit 143 include data signals, which are optical signals transmitted by the optical transmitter 13 in the data signal transmission process described above.

[0031] The optical signal receiving unit 143 provides the control unit 145 with information representing the reception status of the optical signal in the optical receiver 14 (hereinafter also referred to as "reception status information") as an electrical signal. In this embodiment, the reception status of the optical signal in the optical receiver 14 is the same as the reception status of the optical signal in the optical signal receiving unit 143. If the optical signal receiving unit 143 is not receiving an optical signal, it provides the control unit 145 with reception status information indicating a no-signal state. This reception status information indicating a no-signal state is sometimes called LOS (Loss Of Signal). Also, if the optical signal receiving unit 143 is receiving an optical signal, it provides the control unit 145 with reception status information indicating the intensity of the optical signal being received. This reception status information indicating the intensity of the optical signal being received is sometimes called RSSI (Received Signal Strength Indicator).

[0032] The control unit 145 periodically (in other words, repeatedly at regular time intervals) generates a control signal that includes the ID of the optical receiver 14 and reception status information obtained from the optical signal receiving unit 143. For example, the control unit 145 periodically generates a CAN (Controller Area Network) frame message or a CAN / FD (Controller Area Network / Flexible Data-rate) frame message as a control signal that includes the ID of the optical receiver 14 and reception status information obtained from the optical signal receiving unit 143. In this case, the ID can be stored, for example, in the ID field of the CAN frame message or CAN / FD frame message, and the reception status information can be stored, for example, in the DATA field.

[0033] The electrical signal communication unit 144 is configured to transmit electrical signals to the optical transmitter 13 via the telecommunication channel 12. The electrical signal communication unit 144 can be implemented, for example, by a known electrical modulation circuit. The electrical signal communication unit 144 periodically (in other words, repeatedly at regular time intervals) performs control signal transmission processing. Control signal transmission processing is the process of transmitting control signals acquired from the control unit 145 as electrical signals to the optical transmitter 13 via the telecommunication channel 12.

[0034] (Specific examples of optical communication systems) A specific example of the optical communication system 1, the in-vehicle video transmission system 1A, will be explained with reference to Figure 2. Figure 2 is a block diagram showing the configuration of the in-vehicle video transmission system 1A.

[0035] In the in-vehicle video transmission system 1A, the optical communication path 11 is an optical fiber housed in an optical cable, and the telecommunication path 12 is a metal wire housed in an electrical cable. The optical cable housing the optical communication path 11 and the electrical cable housing the telecommunication path 12 are bundled together. That is, the optical cable housing the optical communication path 11 and the electrical cable housing the telecommunication path 12 constitute a harness. In addition, in the in-vehicle video transmission system 1A, the optical transmitter 13 is a camera, and the optical receiver 14 is an ECU (Electronic Control Unit).

[0036] The camera, which is the optical transmitter 13, includes an optical connector 131, an electrical connector 132, an optical signal transmission unit 133, an electrical signal communication unit 134, and a control unit 135, in addition to an image sensor 137. The image sensor 137 generates an electrical video signal and provides it to the optical signal transmission unit 133. The optical signal transmission unit 133 generates an optical data signal by modulating carrier light with the video signal acquired from the image sensor 137, and transmits the generated data signal to the optical receiver 14 via the optical communication path 11.

[0037] The ECU, which is the optical receiver 14, includes an optical connector 141, an electrical connector 142, an optical signal receiving unit 143, an electrical signal communication unit 144, and a control unit 145, in addition to a processor 146. The optical signal receiving unit 143 generates an electrical signal, which is a video signal, by demodulating the data signal received from the optical transmitter 13 via the optical communication path 11 and provides it to the processor 146. The processor 146 performs predetermined processing on the video signal acquired from the optical signal receiving unit 143.

[0038] It should be noted that in optical communication system 1, the optical transmitter 13 and optical receiver 14 do not have a high-performance communication interface such as I2C. Optical communication system 1 has a function to prevent signal light from entering the eyes of workers performing mating or unmating operations on optical connectors, as will be described later, and it is noteworthy that this function is realized without relying on a high-performance communication interface such as I2C.

[0039] Furthermore, the optical communication system 1 can also be implemented as an AOC (Active Optical Cable) for connecting the camera and the ECU. In this case, the optical communication path 11 is an optical fiber, the electrical communication path 12 is a metal wire, the optical transmitter 13 is a camera-side connector connected to the camera, and the optical receiver 14 is an ECU-side connector connected to the ECU.

[0040] In this case, the optical signal transmission unit 133 built into the camera-side connector generates a data signal, which is an optical signal, by modulating the carrier light with the video signal acquired from the image sensor built into the camera. In this case, the video signal, which is an electrical signal obtained by demodulating the data signal, is provided to the processor 146 built into the ECU.

[0041] (Example of an optical communication system) The optical transmitter 13 may include an optical signal receiving unit in addition to an optical signal transmitting unit 133 that transmits optical signals. Similarly, the optical receiver 14 may include an optical signal transmitting unit in addition to an optical signal receiving unit 143 that receives optical signals. In other words, the optical communication system 1 may be a system that performs unidirectional optical communication or a system that performs bidirectional optical communication. When performing bidirectional optical communication, two optical fibers may be used as the optical communication path 11. In this case, one optical fiber is used to transmit optical signals from the optical transmitter 13 to the optical receiver 14, and the other optical fiber is used to transmit optical signals from the optical receiver 14 to the optical transmitter 13.

[0042] Furthermore, the electrical signal communication unit 134 of the optical transmitter 13 may have the function of transmitting electrical signals to the optical receiver 14 in addition to the function of receiving electrical signals from the optical receiver 14. Similarly, the electrical signal communication unit 144 of the optical receiver 14 may have the function of receiving electrical signals from the optical transmitter 13 in addition to the function of transmitting electrical signals to the optical transmitter 13. In other words, the optical communication system 1 may be a system that performs one-way electrical communication or a system that performs two-way electrical communication. When performing two-way electrical communication, two metal wires may be used as the electrical communication path 12. In this case, one metal wire is used for transmitting electrical signals from the optical receiver 14 to the optical transmitter 13, and the other metal wire is used for transmitting electrical signals from the optical transmitter 13 to the optical receiver 14.

[0043] (Operation of the optical transmitter) The main feature of optical communication system 1 lies in the operation of the optical transmitter 13 before data signal transmission processing begins. The operation of the optical transmitter 13 will be explained below with reference to Figures 3 to 5. Figures 3 to 5 are flowcharts showing the flow of operation of the optical transmitter 13.

[0044] As shown in Figures 3 to 5, the optical transmitter 13 executes the following processes: first prohibition process S11, first alert output process S12, first determination process S13, second alert output process S14, second determination process S15, third alert output process S16 (all shown in Figure 3), permission process S17, test signal transmission process S18, second prohibition process S19, fourth alert output process S20, third determination process S21, third prohibition process S22, fifth alert output process S23 (all shown in Figure 4), data signal transmission process S24, fourth prohibition process S25, sixth alert output process S26, fourth determination process S27, fifth prohibition process S28, and seventh alert output process S29 (all shown in Figure 5). These processes will be explained in order below.

[0045] The optical transmitter 13 first performs a first prohibition process S11. The first prohibition process S11 is a process to transition the state of the optical transmitter 13 from an permitted state to a prohibited state, that is, a process to prohibit the transmission of optical signals by the optical signal transmission unit 133. The first prohibition process S11 is implemented, for example, by setting the value of the TxDisable signal supplied by the control unit 135 to the optical signal transmission unit 133 to High. After completing the first prohibition process S11, the optical transmitter 13 waits for a control signal, which is an electrical signal transmitted from the optical receiver 14 via the telecommunication channel 12. Here, the time during which the optical transmitter 13 waits for the control signal (hereinafter also referred to as the "waiting time") is set to be longer than the period during which the optical receiver 14 transmits the control signal.

[0046] If the optical transmitter 13 fails to receive a control signal within the waiting time, it executes the first alert output process S12 to terminate the series of operations. The first alert output process S12 is a process for outputting an alert to notify the user that the optical transmitter 13 is not electrically connected to the optical receiver 14. The first alert output process S12 is implemented, for example, by (1) the control unit 135 generating a first alert signal, which is an electrical signal indicating that the optical transmitter 13 is not electrically connected to the optical receiver 14, and (2) the electrical signal communication unit 134 transmitting the generated first alert signal to the monitoring device 16 via the telecommunication channel 15. In this case, the monitoring device 16, upon receiving the first alert signal, outputs an alert message as an image or sound indicating that the optical transmitter 13 is not electrically connected to the optical receiver 14.

[0047] If the optical transmitter 13 successfully receives a control signal within the waiting time, it executes the first determination process S13. The first determination process S13 is a process for determining whether the optical receiver 14, which is electrically connected to the optical transmitter 13, is an optical receiver predetermined to be the target of the data signal transmission (hereinafter also referred to as the "target optical receiver"). The first determination process S13 is implemented, for example, by the control unit 135 comparing two IDs, namely the ID included in the control signal received from the optical receiver 14 and the ID of the optical receiver predetermined to be the target of the data signal transmission. The control unit 135 determines that (a) if the two IDs match, the optical receiver 14 electrically connected to the optical transmitter 13 is the target optical receiver, and (b) if the two IDs do not match, the optical receiver 14 electrically connected to the optical transmitter 13 is not the target optical receiver.

[0048] If the optical receiver 14 electrically connected to the optical transmitter 13 is not the target optical receiver, the optical transmitter 13 executes a second alert output process S14 to terminate the series of operations. The second alert output process S14 is a process for outputting an alert to notify the user that the optical receiver 14 electrically connected to the optical transmitter 13 is not the target optical receiver. The second alert output process S14 is implemented, for example, by (1) the control unit 135 generating a second alert signal, which is an electrical signal indicating that the optical receiver 14 electrically connected to the optical transmitter 13 is not the target optical receiver, and (2) the electrical signal communication unit 134 transmitting the generated second alert signal to the monitoring device 16 via the telecommunication channel 15. In this case, the monitoring device 16 that receives the second alert signal outputs an alert message as an image or sound indicating that the optical receiver 14 electrically connected to the optical transmitter 13 is not the target optical receiver.

[0049] If the optical receiver 14 electrically connected to the optical transmitter 13 is the target optical receiver, the optical transmitter 13 executes the second determination process S15. The second determination process S15 is a process for determining whether or not the optical transmitter optically connected to the optical receiver 14 is the optical transmitter 13. The second determination process S15 is realized, for example, by the control unit 135 comparing two states: the reception state of the optical signal indicated by the reception state information included in the control signal received from the optical receiver 14, and the transmission state of the optical signal indicated by the transmission state information obtained from the optical signal transmission unit 133. The control unit 135 determines that (a) if the two states match, the optical transmitter optically connected to the optical receiver 14 is the optical transmitter 13, and (b) if the two states do not match, the optical transmitter optically connected to the optical receiver 14 is not the optical transmitter 13.

[0050] At the time the second determination process S15 is executed, the transmission of optical signals by the optical signal transmission unit 133 is prohibited, and the transmission status information obtained from the optical signal transmission unit 133 indicates a no-signal state. Therefore, the control unit 135 determines that (a) if the reception status information included in the control signal received from the optical receiver 14 indicates a no-signal state, the optical transmitter optically connected to the optical receiver 14 is the optical transmitter 13, and (b) if the reception status information included in the control signal received from the optical receiver 14 indicates a reception state other than a no-signal state, the optical transmitter optically connected to the optical receiver 14 is not the optical transmitter 13.

[0051] If the optical transmitter optically connected to the optical receiver 14 is not the optical transmitter 13, the optical transmitter 13 executes the third alert output process S16 and terminates the series of operations. The third alert output process S16 is a process for outputting an alert to notify the user that the optical transmitter optically connected to the optical receiver 14 is not the optical transmitter 13. The third alert output process S16 is implemented, for example, by (1) the control unit 135 generating a third alert signal, which is an electrical signal indicating that the optical transmitter optically connected to the optical receiver 14 is not the optical transmitter 13, and (2) the electrical signal communication unit 134 transmitting the generated third alert signal to the monitoring device 16 via the telecommunication channel 15. In this case, the monitoring device 16, upon receiving the third alert signal, outputs an alert message as an image or sound indicating that the optical transmitter optically connected to the optical receiver 14 is not the optical transmitter 13.

[0052] If the optical transmitter optically connected to the optical receiver 14 is the optical transmitter 13, the optical transmitter 13 performs permission processing S17. Permission processing S17 is a process to permit the transmission of an optical signal by the optical signal transmission unit 133. Permission processing S17 is achieved, for example, by setting the value of the TxDisable signal supplied by the control unit 135 to the optical signal transmission unit 133 to Low.

[0053] Upon completion of the authorization process S17, the optical transmitter 13 starts the test signal transmission process S18. The test signal transmission process S18 is the process of transmitting a test signal, which is an optical signal with lower power than the data signal, to the optical receiver 14 via the optical communication channel 11. The test signal transmission process S18 is realized, for example, by the optical signal transmission unit 133 performing short pulse oscillation. Upon starting the test signal transmission process S18, the optical transmitter 13 waits for a control signal, which is an electrical signal transmitted from the optical receiver 14 via the telecommunication channel 12. Here, the time during which the optical transmitter 13 waits for the control signal (hereinafter also referred to as the "waiting time") is set to be longer than the period during which the optical receiver 14 transmits the control signal.

[0054] If the optical transmitter 13 fails to receive the control signal within the waiting time, it terminates the series of operations by executing the second prohibition process S19 and the fourth alert output process S20. The second prohibition process S19 is a process to transition the state of the optical transmitter 13 from an permitted state to a prohibited state, that is, a process to prohibit the transmission of optical signals by the optical signal transmission unit 133. The second prohibition process S19 is implemented, for example, by setting the value of the TxDisable signal supplied by the control unit 135 to the optical signal transmission unit 133 to High. The fourth alert output process S20 is a process to output an alert to notify the user that an abnormality has occurred in the electrical connection between the optical transmitter 13 and the optical receiver 14. The fourth alert output process S20 is implemented, for example, by (1) the control unit 135 generating a fourth alert signal, which is an electrical signal indicating that an abnormality has occurred in the electrical connection between the optical transmitter 13 and the optical receiver 14, and (2) the electrical signal communication unit 134 transmitting the generated fourth alert signal to the monitoring device 16 via the telecommunication channel 15. In this case, the monitoring device 16, upon receiving the fourth alert signal, outputs an alert message as an image or sound indicating that an abnormality has occurred in the electrical connection between the optical transmitter 13 and the optical receiver 14.

[0055] If the optical transmitter 13 successfully receives the control signal within the waiting time, it executes the third determination process S21. The third determination process S21 is a process for determining whether or not there is an abnormality in the optical connection between the optical transmitter 13 and the optical receiver 14. The third determination process S21 is realized, for example, by comparing two states: the reception state of the optical signal indicated by the reception state information included in the control signal received from the optical receiver 14, and the transmission state of the optical signal indicated by the transmission state information obtained from the optical signal transmission unit 133. The control unit 135 determines that (a) if the two states match, there is no abnormality in the optical connection between the optical transmitter 13 and the optical receiver 14, and (b) if the two states do not match, there is an abnormality in the optical connection between the optical transmitter 13 and the optical receiver 14.

[0056] At the time the third determination process S21 is executed, the optical signal transmission unit 133 transmits a test signal, and the transmission status information indicates the intensity of the test signal. Therefore, the control unit 135 determines that (a) if the reception status information included in the received control signal indicates an intensity corresponding to the intensity of the transmitted test signal, there is no abnormality in the optical connection between the optical transmitter 13 and the optical receiver 14, and (b) if the reception status information included in the received control signal indicates a reception status other than the intensity corresponding to the intensity of the transmitted test signal, there is an abnormality in the optical connection between the optical transmitter 13 and the optical receiver 14. Here, "intensity corresponding to the intensity of the test signal" refers to, for example, the intensity obtained by subtracting the expected loss from the intensity of the test signal, or the intensity where the difference between this and the intensity obtained by subtracting the expected loss from the intensity of the test signal is less than a predetermined threshold.

[0057] If an abnormality occurs in the optical connection between the optical transmitter 13 and the optical receiver 14, the optical transmitter 13 terminates the series of operations by executing the third prohibition process S22 and the fifth alert output process S23. The third prohibition process S22 is a process to prohibit the transmission of optical signals by the optical signal transmission unit 133. The third prohibition process S22 is implemented, for example, by setting the value of the TxDisable signal supplied by the control unit 135 to the optical signal transmission unit 133 to High. The fifth alert output process S23 is a process to output an alert to notify the user that an abnormality has occurred in the optical connection between the optical transmitter 13 and the optical receiver 14. The fifth alert output process S23 is implemented, for example, by (1) the control unit 135 generating a fifth alert signal, which is an electrical signal indicating that an abnormality has occurred in the optical connection between the optical transmitter 13 and the optical receiver 14, and (2) the electrical signal communication unit 134 transmitting the generated fifth alert signal to the monitoring device 16 via the telecommunication channel 15. In this case, the monitoring device 16, upon receiving the fifth alert signal, outputs an alert message as an image or sound indicating that an abnormality has occurred in the optical connection between the optical transmitter 13 and the optical receiver 14.

[0058] If there is no abnormality in the optical connection between the optical transmitter 13 and the optical receiver 14, the optical transmitter 13 terminates the test signal transmission process S18 and starts the data signal transmission process S24. The data signal transmission process S24 is a process for transmitting a data signal, which is an optical signal, to the optical receiver 14 via the optical communication channel 11. The data signal transmission process S24 is realized, for example, by the optical signal transmission unit 133 converting a data signal (e.g., video data) acquired from a signal source (e.g., an image sensor) into an optical signal and transmitting it. When the data signal transmission process S24 starts, the optical transmitter 13 waits for a control signal, which is an electrical signal, transmitted from the optical receiver 14 via the telecommunication channel 12. Here, the time during which the optical transmitter 13 waits for the control signal (hereinafter also referred to as "waiting time") is set to be longer than the period during which the optical receiver 14 transmits the control signal.

[0059] If the optical transmitter 13 fails to receive a control signal within the waiting time, it terminates the series of operations by executing the fourth prohibition process S25 and the sixth alert output process S26. The fourth prohibition process S25 is a process to transition the state of the optical transmitter 13 from an permitted state to a prohibited state, that is, a process to prohibit the transmission of optical signals by the optical signal transmission unit 133. The fourth prohibition process S25 is implemented, for example, by setting the value of the TxDisable signal supplied by the control unit 135 to the optical signal transmission unit 133 to High. The sixth alert output process S26 is a process to output an alert to notify the user that an abnormality has occurred in the electrical connection between the optical transmitter 13 and the optical receiver 14. The sixth alert output process S26 is implemented, for example, by (1) the control unit 135 generating a sixth alert signal, which is an electrical signal indicating that an abnormality has occurred in the electrical connection between the optical transmitter 13 and the optical receiver 14, and (2) the electrical signal communication unit 134 transmitting the generated sixth alert signal to the monitoring device 16 via the telecommunication channel 15. In this case, the monitoring device 16, upon receiving the sixth alert signal, outputs an alert message as an image or sound indicating that there is an abnormality in the electrical connection between the optical transmitter 13 and the optical receiver 14.

[0060] If the optical transmitter 13 successfully receives the control signal within the waiting time, it executes the fourth determination process S27. The fourth determination process S27 is a process for determining whether or not there is an abnormality in the optical connection between the optical transmitter 13 and the optical receiver 14. The fourth determination process S27 is realized, for example, by comparing two states: the reception state of the optical signal indicated by the reception state information included in the control signal received from the optical receiver 14, and the transmission state of the optical signal indicated by the transmission state information obtained from the optical signal transmission unit 133. The control unit 135 determines that (a) if the two states match, there is no abnormality in the optical connection between the optical transmitter 13 and the optical receiver 14, and (b) if the two states do not match, there is an abnormality in the optical connection between the optical transmitter 13 and the optical receiver 14.

[0061] At the time the fourth determination process S27 is executed, the optical signal transmission unit 133 is transmitting a data signal, and the transmission status information indicates the intensity of the data signal. Therefore, the control unit 135 determines that (a) if the reception status information included in the received control signal indicates an intensity corresponding to the intensity of the transmitted data signal, there is no abnormality in the optical connection between the optical transmitter 13 and the optical receiver 14, and (b) if the reception status information included in the received control signal indicates a reception status other than the intensity corresponding to the intensity of the transmitted data signal, there is an abnormality in the optical connection between the optical transmitter 13 and the optical receiver 14. Here, "intensity corresponding to the intensity of the data signal" refers to, for example, the intensity obtained by subtracting the expected loss from the intensity of the data signal, or the intensity where the difference between this and the intensity obtained by subtracting the expected loss from the intensity of the data signal is less than a predetermined threshold.

[0062] If an abnormality occurs in the optical connection between the optical transmitter 13 and the optical receiver 14, the optical transmitter 13 terminates the series of operations by executing the fifth prohibition process S28 and the seventh alert output process S29. The fifth prohibition process S28 is a process to prohibit the transmission of optical signals by the optical signal transmission unit 133. The fifth prohibition process S28 is implemented, for example, by setting the value of the TxDisable signal supplied by the control unit 135 to the optical signal transmission unit 133 to High. The seventh alert output process S29 is a process to output an alert to notify the user that an abnormality has occurred in the optical connection between the optical transmitter 13 and the optical receiver 14. The seventh alert output process S29 is implemented, for example, by (1) the control unit 135 generating a seventh alert signal, which is an electrical signal indicating that an abnormality has occurred in the optical connection between the optical transmitter 13 and the optical receiver 14, and (2) the electrical signal communication unit 134 transmitting the generated seventh alert signal to the monitoring device 16 via the telecommunication channel 15. In this case, the monitoring device 16, upon receiving the seventh alert signal, outputs an alert message as an image or sound indicating that an abnormality has occurred in the optical connection between the optical transmitter 13 and the optical receiver 14.

[0063] If there is no abnormality in the optical connection between the optical transmitter 13 and the optical receiver 14, the optical transmitter 13 continues the data signal transmission process S24 and waits for the control signal, which is an electrical signal, to be transmitted again from the optical receiver 14 via the telecommunication channel 12. The cycle including the fourth prohibition process S25, the sixth alert output process S26, the fourth determination process S27, the fifth prohibition process S28, and the seventh alert output process S29 is repeated until the end of the data signal to be transmitted (EOD: End Of Data) has been transmitted.

[0064] In this embodiment, the optical transmitter 13 is configured to send an alert signal to the monitoring device 16 when various abnormalities occur, but it is not limited to this. For example, a configuration may be adopted in which an alert signal is sent to a higher-level device that comprehensively controls the entire optical communication system 1 when various abnormalities occur. In this case, the higher-level device may output a message to inform the user that various abnormalities have occurred, or it may control the monitoring device to output a message to inform the user that various abnormalities have occurred. Alternatively, a configuration may be adopted in which the optical transmitter 13 itself outputs a message to inform the user that various abnormalities have occurred when various abnormalities occur.

[0065] (Effects of optical communication systems) If the optical connection between the optical transmitter 13 and the optical receiver 14 is abnormal, such as when the optical connectors 11c and 11d included in the optical communication channel 11 are disengaged, and the optical transmitter 13 starts or continues the data signal transmission process S24, there is a risk that the data signal, which is a high-power optical signal, will enter the eyes of the worker. The operation of the optical transmitter 13 described above is designed with the intention of providing the optical communication system 1 with an eye safety function to reduce such risks.

[0066] In fact, in the optical communication system 1, the optical receiver 14 transmits a control signal indicating the reception status of the optical signal in the optical receiver 14 to the optical transmitter 13 via the telecommunication channel 12, and the optical transmitter 13 receives this control signal from the optical receiver 14 via the telecommunication channel 12. The optical transmitter 13 then starts or continues the data signal transmission process S24 only if the control signal received from the optical receiver 14 via the telecommunication channel 12 indicates a reception status that matches the transmission status of the optical signal in the optical transmitter 13 (third determination process S21: YES, fourth determination process S27: YES).

[0067] Therefore, in the optical communication system 1, the data signal transmission process S24 is started or continued only when the transmission state of the optical signal in the optical transmitter 13 and the reception state of the optical signal in the optical receiver 14 are matched, that is, when there is no abnormality in the optical connection between the optical transmitter 13 and the optical receiver 14. Thus, the risk of the data signal, which is a strong optical signal, entering the eyes of the worker can be reduced.

[0068] Furthermore, in the optical communication system 1, the optical transmitter 13 executes a test signal transmission process S18 prior to the data signal transmission process S24, and only if the control signal received from the optical receiver 14 during the execution of the test signal transmission process S18 indicates a reception state that matches the transmission state of the optical signal in the optical transmitter 13 (third determination process S21: YES), the optical transmitter 13 starts the data signal transmission process.

[0069] Therefore, in the optical communication system 1, if it is confirmed that the transmission state of the optical signal in the optical transmitter 13 and the reception state of the optical signal in the optical receiver 14 do not match before the data signal transmission process S24 is executed, that is, if an abnormality occurs in the optical connection between the optical transmitter 13 and the optical receiver 14, the data signal transmission process S24 will not be started. Consequently, the risk of the data signal, which is a strong optical signal, entering the eyes of an operator can be further reduced.

[0070] Furthermore, in the optical communication system 1, the optical transmitter 13 continues the data signal transmission process only if the control signal received from the optical receiver 14 during the execution of the test signal transmission process S18 indicates a reception state that matches the transmission state of the optical signal in the optical transmitter 13 (fourth determination process S27: YES).

[0071] Therefore, in the optical communication system 1, if it is confirmed that the transmission state of the optical signal in the optical transmitter 13 and the reception state of the optical signal in the optical receiver 14 do not match during the execution of the data signal transmission process S24, that is, if an abnormality occurs in the optical connection between the optical transmitter 13 and the optical receiver 14, the data signal transmission process S24 will not continue. Thus, the risk of the data signal, which is a strong optical signal, entering the eyes of an operator can be further reduced.

[0072] Furthermore, in the optical communication system 1, if the control signal received by the optical receiver 14 via the telecommunication channel 12 indicates a reception state that does not match the transmission state of the optical signal in the optical transmitter 13 (third determination process S21: NO, fourth determination process S27: NO), the optical transmitter 13 executes alert output processes S23 and S29 to indicate that an abnormality has occurred in the optical connection between the optical transmitter 13 and the optical receiver 14.

[0073] Therefore, in the optical communication system 1, an alert can be sent to the user to inform them that an abnormality has occurred in the optical connection between the optical transmitter 13 and the optical receiver 14.

[0074] Furthermore, in the optical communication system 1, the optical transmitter 13 has a prohibited state in which the transmission of optical signals is prohibited and a permitted state in which the transmission of optical signals is permitted, and the control signal indicates the reception status of the optical signal in the optical receiver 14 as well as the ID of the optical receiver 14. The optical transmitter 13 transitions its state from the prohibited state to the permitted state only when the control signal received from the optical receiver 14 while the state of the optical transmitter 13 is in the prohibited state indicates the ID of a target optical receiver predetermined as the target of the data signal transmission (first determination process S13: YES).

[0075] Therefore, in the optical communication system 1, it is possible to avoid the transmission of an optical signal from the optical transmitter 13 when the optical receiver 14 electrically connected to the optical transmitter 13 is not the target optical receiver, that is, when the optical transmitter 13 and the target optical receiver are optically connected but the eye safety function using the control signal is not effectively working.

[0076] Furthermore, in the optical communication system 1, if the optical transmitter 13 is in a prohibited state and the control signal received from the optical receiver 14 indicates an ID other than that of the target optical receiver (first determination process S13: NO), the optical transmitter 13 executes a second alert output process S14 to output an alert indicating that the optical receiver 14 electrically connected to the optical transmitter 13 is not the target optical receiver.

[0077] Therefore, in the optical communication system 1, the user can be notified by an alert that the optical receiver 14 electrically connected to the optical transmitter 13 is not the target optical receiver.

[0078] Furthermore, in the optical communication system 1, the optical transmitter 13 has a prohibited state in which the transmission of optical signals is prohibited and a permitted state in which the transmission of optical signals is permitted. The state of the optical transmitter 13 is changed from the prohibited state to the permitted state only when the control signal received from the optical receiver 14 indicates a no-signal state (second determination process S15: YES) while the state of the optical transmitter 13 is prohibited.

[0079] Therefore, in the optical communication system 1, it is possible to avoid the transmission of an optical signal from the optical transmitter 13 when the optical transmitter 13, which is optically connected to the optical receiver 14, is not the optical transmitter 13; that is, when the optical transmitter 13 and the optical receiver 14 are electrically connected but the eye safety function using control signals is not effectively working.

[0080] Furthermore, in the optical communication system 1, if the optical transmitter 13 is in a prohibited state and the control signal received from the optical receiver 14 indicates a reception state other than no signal, the optical transmitter 13 executes a third alert output process S16 to output an alert indicating that the optical transmitter optically connected to the optical receiver 14 is not the optical transmitter 13.

[0081] Therefore, in the optical communication system 1, the user can be notified by an alert that the optical transmitter optically connected to the optical receiver 14 is not the optical transmitter 13.

[0082] (Secondary effects of optical communication systems) Normally, unlike telecommunications, optical communication does not generate leaking electromagnetic waves. Therefore, when eavesdropping occurs, it is expected that the optical connector will be unplugged and the data signal, which is an optical signal, will be directly observed. In contrast, in the optical communication system 1 according to this embodiment, if the optical connector is unplugged before the data signal transmission process S24 starts, the data signal transmission process S24 will not start. Also, if the optical connector is unplugged after the data signal transmission process S24 has started, the data signal transmission process S24 will be interrupted. Therefore, eavesdropping on the data signal, which is an optical signal, can be prevented.

[0083] (Use of composite cables) The optical transmitter 13 and the optical receiver 14 may be connected using two cables, namely an optical cable containing the optical communication channel 11 and an electrical cable containing the telecommunication channel 12, or they may be connected using one cable, namely a composite cable containing the optical communication channel 11 and the telecommunication channel 12.

[0084] Figure 6 shows an example of a composite cable containing an optical communication channel 11 and an telecommunication channel 12. Figure 6 is a cross-sectional view of a composite cable 10 containing an optical communication channel 11 and an telecommunication channel 12. The composite cable 10 shown in Figure 6 is suitable for cases where bidirectional optical communication is possible. That is, it is suitable for cases where the optical transmitter 13 has the function of receiving optical signals in addition to the function of transmitting optical signals, and the optical receiver 14 has the function of transmitting optical signals in addition to the function of receiving optical signals.

[0085] The composite cable 10 shown in Figure 6 includes two optical fibers 111 and 112 that function as an optical communication channel 11, and two metal wires 121 and 122 that function as an electrical communication channel 12. One of the two optical fibers 111 and 112 is used to transmit an optical signal transmitted from the optical transmitter 13 to the optical receiver 14, and the other of the two optical fibers 111 and 112 is used to transmit an optical signal transmitted from the optical receiver 14 to the optical transmitter 13. The two metal wires 121 and 122 are twisted together to form a differential signal line. The two metal wires 121 and 122 are used to transmit an electrical signal transmitted from the optical receiver 14 to the optical transmitter 13, and to transmit an electrical signal transmitted from the optical transmitter 13 to the optical receiver 14.

[0086] A composite connector that simultaneously achieves optical and electrical connections is used for connecting the composite cable 10 to the optical transmitter 13, and for connecting the composite cable 10 to the optical receiver 14. The same applies to connecting two composite cables 10 together. Therefore, when using the composite cable 10, it is less likely to occur, compared to when using two separate cables, that the optical transmitter 13 and optical receiver 14 are optically connected via the optical communication path 11, but are not electrically connected via the telecommunication path 12.

[0087] However, if the metal wires 121 and 122 inside the composite cable 10 break or if the electrical circuit inside the composite connector malfunctions, the above condition can be realized. Therefore, even when the optical transmitter 13 and the optical receiver 14 are connected using a single cable (composite cable 10), there is a problem that strong optical signals, such as data signals, may enter the eyes of the worker performing the mating or unmating operation, just as when the optical transmitter 13 and the optical receiver 14 are connected using two cables (optical cable and electrical cable). Therefore, even when the optical transmitter 13 and the optical receiver 14 are connected using a single cable, the risk of strong optical signals, such as data signals, entering the eyes of the worker performing the mating or unmating operation is reduced, just as when the optical transmitter 13 and the optical receiver 14 are connected using two cables.

[0088] (Additional information) In vehicle control systems such as autonomous driving, the ECU controls various parts of the vehicle based on video signals acquired from a camera. If an abnormality occurs in the in-vehicle video transmission system used to acquire video signals, it is preferable for the ECU to control the vehicle to a safe state, such as by stopping the vehicle. However, if an abnormality occurs in which the electrical connection between the camera and the ECU is lost without the optical connection between the camera and the ECU being lost, the ECU will not be able to recognize the occurrence of the abnormality as long as the transmission of video signals from the camera to the ECU continues, and as a result, the ECU will not be able to control the vehicle to a safe state.

[0089] This problem can be solved by using the in-vehicle video transmission system 1A, which is a specific example of the optical communication system 1. Specifically, the camera (optical transmitter 13) included in the in-vehicle video transmission system 1A transmits a video signal only when an electrical connection is established between the camera (optical transmitter 13) and the ECU (optical receiver 14). Therefore, if an abnormal situation occurs in which the electrical connection between the camera (optical transmitter 13) and the ECU (optical receiver 14) is interrupted, the ECU (optical receiver 14) can recognize the occurrence of this abnormal situation by the interruption of the video signal and control the vehicle to a safe state.

[0090] (summary) The optical communication system according to Embodiment 1 includes an optical communication path, an telecommunication path, an optical receiver optically connected to one end of the optical communication path and electrically connected to one end of the telecommunication path, and an optical transmitter optically connected to the other end of the optical communication path and electrically connected to the other end of the telecommunication path, wherein the optical receiver transmits a control signal indicating the reception state of an optical signal in the optical receiver to the optical transmitter via the telecommunication path, and the optical transmitter receives the control signal from the optical receiver via the telecommunication path and starts or continues a data signal transmission process that transmits a data signal, which is an optical signal, to the optical receiver via the optical communication path only when the control signal indicates a reception state that matches the transmission state of an optical signal in the optical transmitter.

[0091] The optical communication system according to Embodiment 2 is the optical communication system according to Embodiment 1, wherein the optical transmitter performs a test signal transmission process in advance of the data signal transmission process, by transmitting a test signal, which is an optical signal with lower power than the data signal, to the optical receiver via the optical communication path, and only starts the data signal transmission process if the control signal received from the optical receiver during the execution of the test signal transmission process indicates a reception state that matches the transmission state of the optical signal in the optical transmitter.

[0092] The optical communication system according to embodiment 3 is the optical communication system according to embodiment 1 or 2, wherein the optical transmitter continues the data signal transmission process only when the control signal received from the optical receiver during the execution of the data signal transmission process indicates a reception state that is consistent with the transmission state of the optical signal in the optical transmitter.

[0093] The optical communication system according to Embodiment 4 is an optical communication system according to any one of Embodiments 1 to 3, wherein the optical transmitter performs an alert output process to output an alert indicating that an abnormality has occurred in the optical connection between the optical transmitter and the optical receiver when the control signal indicates a reception state that does not match the transmission state of the optical signal in the optical transmitter.

[0094] The optical communication system according to Embodiment 5 is an optical communication system according to any one embodiment of Embodiments 1 to 4, wherein the optical transmitter has a prohibited state in which the transmission of optical signals is prohibited and a permitted state in which the transmission of optical signals is permitted, the control signal indicates the ID of the optical receiver in addition to the optical signal reception state of the optical receiver, and the optical transmitter transitions its state from the prohibited state to the permitted state only when the control signal received from the optical receiver while the state of the optical transmitter is the prohibited state indicates the ID of a target optical receiver predetermined as the target of data signal transmission.

[0095] The optical communication system according to embodiment 6 is the optical communication system according to embodiment 5, characterized in that when the optical transmitter is in the prohibited state and the control signal received from the optical receiver indicates an ID other than the ID of the target optical receiver, the optical transmitter performs an alert output process to output an alert indicating that the optical receiver electrically connected to the optical transmitter is not the target optical receiver.

[0096] The optical communication system according to Embodiment 7 is an optical communication system according to any one of Embodiments 1 to 6, wherein the optical transmitter has a prohibited state in which the transmission of an optical signal is prohibited and a permitted state in which the transmission of an optical signal is permitted, and the optical transmitter transitions its state from the prohibited state to the permitted state only when the control signal received from the optical receiver indicates a no-signal state while the state of the optical transmitter is the prohibited state.

[0097] The optical communication system according to embodiment 8 is the optical communication system according to embodiment 7, wherein when the optical transmitter is in the prohibited state and the control signal received from the optical receiver indicates a reception state other than no signal state, the optical transmitter performs an alert output process to output an alert indicating that the optical transmitter optically connected to the optical receiver is not the optical transmitter.

[0098] The communication system according to embodiment 9 is an optical communication system according to any one of embodiments 1 to 8, wherein the optical receiver repeatedly transmits the control signal to the optical transmitter via the telecommunication path at regular time intervals.

[0099] The optical communication system according to embodiment 10 is an optical communication system according to any one embodiment of embodiments 1 to 9, wherein the optical communication path is an optical fiber included in a composite cable, and the telecommunication path is a metal wire included in the composite cable.

[0100] The optical communication system according to embodiment 11 is an optical communication system according to any one embodiment of embodiments 1 to 10, wherein the optical transmitter is built into or connected to a camera, and the data signal is a data signal representing an image or video captured by the camera.

[0101] The optical communication method according to embodiment 12 is an optical communication method comprising: an optical communication path; an telecommunication path; an optical receiver optically connected to one end of the optical communication path and electrically connected to one end of the telecommunication path; and an optical transmitter optically connected to the other end of the optical communication path and electrically connected to the other end of the telecommunication path, wherein the optical receiver transmits a control signal indicating the reception state of an optical signal in the optical receiver to the optical transmitter via the telecommunication path; the optical transmitter receives the control signal from the optical receiver via the telecommunication path and, only when the control signal indicates a reception state consistent with the transmission state of an optical signal in the optical transmitter, starts or continues a data signal transmission process that transmits a data signal, which is an optical signal, to the optical receiver via the optical communication path.

[0102] The optical transmitter according to embodiment 13 is an optical transmitter that is optically connected to the other end of an optical communication path to which an optical receiver is optically connected at one end, and electrically connected to the other end of an telecommunication path to which the optical receiver is electrically connected at one end, and receives a control signal indicating the reception state of an optical signal in the optical receiver from the optical receiver via the telecommunication path, and starts or continues a data signal transmission process that transmits a data signal, which is an optical signal, to the optical receiver via the optical communication path only when the control signal indicates a reception state that matches the transmission state of an optical signal in the optical transmitter.

[0103] (Additional notes) The present invention is not limited to the embodiments described above, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in each of the embodiments described above are also included within the technical scope of the present invention. [Explanation of Symbols]

[0104] 1. Optical communication system 11 Optical communication channels 12 Telecommunication Channels 13 Optical Transmitter 14 Optical receiver

Claims

1. The system includes an optical communication channel, an electrical communication channel, an optical receiver optically connected to one end of the optical communication channel and electrically connected to one end of the electrical communication channel, and an optical transmitter optically connected to the other end of the optical communication channel and electrically connected to the other end of the electrical communication channel. The optical receiver transmits a control signal indicating the reception status of the optical signal in the optical receiver to the optical transmitter via the telecommunication channel. The optical transmitter receives the control signal from the optical receiver via the telecommunication channel, and only if the control signal indicates a reception state that matches the transmission state of the optical signal in the optical transmitter, it starts or continues a data signal transmission process that transmits a data signal, which is an optical signal, to the optical receiver via the optical communication channel. Optical communication system.

2. The optical transmitter performs a test signal transmission process prior to the data signal transmission process, which involves transmitting a test signal, which is an optical signal with lower power than the data signal, to the optical receiver via the optical communication path, and only starts the data signal transmission process if the control signal received from the optical receiver during the execution of the test signal transmission process indicates a reception state that matches the transmission state of the optical signal in the optical transmitter. The optical communication system according to claim 1.

3. The optical transmitter continues the data signal transmission process only if the control signal received from the optical receiver during the execution of the data signal transmission process indicates a reception state that is consistent with the transmission state of the optical signal in the optical transmitter. The optical communication system according to claim 1.

4. If the optical transmitter indicates a reception state in which the control signal does not match the transmission state of the optical signal in the optical transmitter, the optical transmitter performs an alert output process to output an alert indicating that an abnormality has occurred in the optical connection between the optical transmitter and the optical receiver. The optical communication system according to claim 1.

5. The optical transmitter has a prohibited state in which the transmission of optical signals is prohibited, and an permitted state in which the transmission of optical signals is permitted. The control signal indicates the reception status of the optical signal in the optical receiver, as well as the ID of the optical receiver. The optical transmitter will transition its state from the prohibited state to the permitted state only if the control signal received from the optical receiver while the optical transmitter is in the prohibited state indicates the ID of a target optical receiver predetermined as the recipient of the data signal. The optical communication system according to claim 1.

6. If the optical transmitter is in the prohibited state and the control signal received from the optical receiver indicates an ID other than the ID of the target optical receiver, the optical transmitter performs an alert output process to output an alert indicating that the optical receiver electrically connected to the optical transmitter is not the target optical receiver. The optical communication system according to feature 5.

7. The optical transmitter has a prohibited state in which the transmission of optical signals is prohibited, and an permitted state in which the transmission of optical signals is permitted. The optical transmitter transitions its state from the prohibited state to the permitted state only when the control signal received from the optical receiver indicates no signal while the optical transmitter is in the prohibited state. The optical communication system according to claim 1.

8. When the optical transmitter is in the prohibited state, if the control signal received from the optical receiver indicates a reception state other than no signal, the optical transmitter performs an alert output process to output an alert indicating that the optical transmitter optically connected to the optical receiver is not the optical transmitter in question. The optical communication system according to claim 7.

9. The optical receiver repeatedly transmits the control signal to the optical transmitter via the telecommunication channel at regular time intervals. The optical communication system according to claim 1.

10. The aforementioned optical communication path is an optical fiber included in a composite cable. The aforementioned telecommunication channel is a metal wire included in the composite cable. The optical communication system according to any one of claims 1 to 9.

11. The aforementioned optical transmitter is built into or connected to the camera. The aforementioned data signal is a data signal representing an image or video captured by the camera. The optical communication system according to any one of claims 1 to 9.

12. An optical communication method comprising: an optical communication channel; an electrical communication channel; an optical receiver optically connected to one end of the optical communication channel and electrically connected to one end of the electrical communication channel; and an optical transmitter optically connected to the other end of the optical communication channel and electrically connected to the other end of the electrical communication channel, The optical receiver transmits a control signal indicating the reception status of the optical signal in the optical receiver to the optical transmitter via the telecommunication channel. The optical transmitter receives the control signal from the optical receiver via the telecommunication channel, and only if the control signal indicates a reception state that matches the transmission state of the optical signal in the optical transmitter, it starts or continues a data signal transmission process that transmits a data signal, which is an optical signal, to the optical receiver via the optical communication channel. Optical communication method.

13. An optical transmitter that is optically connected to the other end of an optical communication channel to which an optical receiver is optically connected at one end, and electrically connected to the other end of an electrical communication channel to which the optical receiver is electrically connected at one end, A control signal indicating the reception status of the optical signal in the optical receiver is received from the optical receiver via the telecommunication channel, and only if the control signal indicates a reception status that matches the transmission status of the optical signal in the optical transmitter, a data signal transmission process is started or continued to transmit a data signal, which is an optical signal, to the optical receiver via the optical communication channel. Optical transmitter.

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