Optical power feeding / communication device, optical power feeding monitoring system, and optical power feeding monitoring method

Abstract

To provide an optical power feeding monitoring system that enables automatic resumption of optical power feeding when an abnormality occurs in an optical fiber cable and the cable is subsequently restored.SOLUTION: An optical power feeding / communication device includes an optical power transmitting unit that optically feeds a sensor with power via a first optical fiber, an optical receiving unit that receives a keep-alive signal from the sensor via a second optical fiber, and a power feeding control unit that switches the optical power feeding by the optical power transmitting unit from normal optical power feeding to short-term intermittent light emission when a change in the reception state of the keep-alive signal occurs. When receiving the keep-alive signal in a normal state after switching to the short-term intermittent light emission, the power feeding control unit switches the short-term intermittent light emission back to the normal optical power feeding.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present disclosure relates to an optical power supply / communication device, an optical power supply monitoring system, and an optical power supply monitoring method. [Background technology]

[0002] With the development of IoT (Internet of Things), a wide variety of sensor networks are being constructed, including temperature sensors, humidity sensors, water level sensors, and wind direction and speed sensors. Optical power supply is being adopted to supply power to these IoT sensors. Optical power supply uses light as an energy source through an optical fiber cable. Compared to electrical wiring, optical fiber is lighter, less susceptible to the effects of temperature and humidity, and generates less noise due to electromagnetic interference. A system has been proposed that automatically stops the output of an optical power supply signal to a power supply optical fiber when an abnormality occurs in the power supply optical fiber (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2016-180669 A Summary of the Invention [Problem to be solved by the invention]

[0004] In optically powered sensor networks, a laser light source is used as the light source for optical power supply. If an abnormality occurs, such as a cut in the optical line for power supply or a loose cable, there is a possibility that light leaks at a level that may affect the human body. Therefore, when an abnormality is detected in the optical fiber cable, the output of the laser light for optical power supply is stopped and an operator at the site must deal with the abnormality in the optical fiber cable. After dealing with the abnormality, the optical power supply must be manually resumed, and an on-site operator must use a dedicated measuring device to determine whether the laser light is normal. There is a need for a configuration that automatically resumes optical power supply when an abnormality occurs in the optical fiber cable and is subsequently restored.

[0005] In one aspect, the present disclosure provides an optical power supply monitoring technique that enables automatic resumption of optical power supply when an abnormality occurs in an optical fiber cable and is subsequently restored. [Means for solving the problem]

[0006] In an embodiment, the optical power supply / communication device includes: an optical power transmitting unit that optically supplies power to the sensor via a first optical fiber; an optical receiver for receiving a keep-alive signal from the sensor via a second optical fiber; a power supply control unit that switches the optical power supply by the optical power transmitting unit from normal optical power supply to short-term intermittent light emission when a reception state of the keep-alive signal changes; having When the keep-alive signal is received in a normal state after switching to the short-time intermittent light emission, the power supply control unit switches from the short-time intermittent light emission to the normal optical power supply. Effect of the Invention

[0007] A power supply monitoring technology is realized that enables automatic resumption of optical power supply when an abnormality occurs in an optical fiber cable and the cable is subsequently restored. [Brief description of the drawings]

[0008] [Figure 1] 1 is a schematic diagram of an optical power supply monitoring system when the power supply optical line is normal. [Diagram 2] 1 is a schematic diagram of an optical power supply monitoring system when an abnormality occurs in an optical power supply line. [Diagram 3] 4 is a time chart of the operation of the optical power supply / communication device. [Figure 4] FIG. 1 is a block diagram of an optical power supply / communication device and a sensor. [Diagram 5] 4 is a flowchart of an optical power supply monitoring method according to the first embodiment. [Figure 6] 10 is a flowchart of an optical power supply monitoring method according to a second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] The optical power supply monitoring technology of the embodiment will be described below with reference to the drawings. The embodiment shown below is an example for embodying the technical idea of ​​the present disclosure, and is not intended to limit the disclosure. The size, positional relationship, etc. of components shown in each drawing may be exaggerated to facilitate understanding of the invention. The same components or functions may be given the same names or symbols, and duplicate explanations may be omitted.

[0010] <Optical power supply monitoring system> 1 is a schematic diagram of an optical power supply monitoring system 100 when an optical fiber line for optical power supply is normal. The optical power supply monitoring system 100 includes a sensor 20, and an optical power supply and communication device (hereinafter referred to as "optical power supply / communication device") 10 that optically supplies power to the sensor 20 and receives data detected by the sensor 20. The sensor 20 is any IoT sensor such as a temperature sensor, humidity sensor, rainfall sensor, wind direction sensor, water level sensor, etc. In this example, the sensor 20 is, for example, a wind direction and speed sensor placed along a railway track. Measurement data of wind direction and speed along the track is one of the materials for judging the safety of vehicle operation such as the Shinkansen.

[0011] When the sensor 20 is installed along a railway line, the distance from the monitoring center to the sensor 20 is long, so instead of supplying power to the sensor 20 electrically, power is supplied by an optical fiber that is lightweight and easy to lay. The sensor 20 and the optical power supply / communication device 10 are connected by a first optical fiber 5 for optical power supply and a second optical fiber 4 for optical communication. Wind direction and wind speed data measured by the sensor 20 is transmitted to the optical power supply / communication device 10 by the second optical fiber 4. The transmission of this measurement data is referred to as uplink optical communication. If necessary, an optical fiber for downlink optical communication from the optical power supply / communication device 10 to the sensor 20 may be provided. In that case, the first optical fiber 5 for optical power supply and the second optical fiber 4 for uplink optical communication, together with a third optical fiber for downlink optical communication, may be covered with resin or the like and used as a single optical fiber cable.

[0012] The wind direction and speed data received by the optical power supply / communication device 10 is transferred to a monitoring server. An optical transmission device connected to the multiple optical power supply / communication devices may be disposed between the optical power supply / communication device 10 and the monitoring server. The optical transmission device receives measurement data from the multiple optical power supply / communication devices 10 and transfers the measurement data to the monitoring server via the optical network.

[0013] When the optical line for optical power supply, i.e., the first optical fiber 5, is in a normal state, the sensor 20 operates using optical power supplied from the optical power supply / communication device 10. The sensor 20 measures wind direction and volume, generates an optical signal representing the measurement data, and transmits the optical signal via the second optical fiber 4 to the optical power supply / communication device 10. The sensor 20 also transmits a keep-alive signal indicating that the sensor 20 is operating. The keep-alive signal is generated by a self-check function of the sensor 20 and transmitted at regular time intervals.

[0014] Fig. 2 is a schematic diagram of the optical power supply monitoring system 100 when an abnormality occurs in the power supply optical line. When an abnormality such as a fiber break, cable disconnection, or insufficient connector insertion occurs in the first optical fiber 5, which is the power supply optical line (Fig. 2 (1)), optical power supply to the sensor 20 is not performed normally. The sensor 20 becomes power-insufficient and is unable to measure wind direction and speed or generate and transmit optical signals containing measurement data (Fig. 2 (2)). The sensor 20 also stops transmitting a keep-alive signal when it is no longer able to receive power supply light.

[0015] When the optical power supply / communication device 10 is no longer able to receive the keep-alive signal normally, it determines that an abnormality has occurred in the first optical fiber 5, and switches the optical power supply mode ((3) in FIG. 2). Specifically, when the keep-alive signal is no longer able to be received normally, it switches from normal optical power supply to abnormal optical power supply. Optical power supply during abnormality is an intermittent power supply emission using short pulses ((4) in FIG. 2). Since short pulse width power supply light is output intermittently at a specified time interval, the amount of power supply light after switching is an amount of light that does not have adverse effects on the human body.

[0016] It is desirable to switch to intermittent emission of short pulses within one second after the keep-alive signal cannot be received normally. "Within one second" means that it is highly unlikely that a worker would get within 100 mm of the broken point of the first optical fiber 5 within one second of the break and be exposed to high levels of power supply light (compliant with JISC 6803 safety standard for optical fiber communication systems). Unlike optical power supply under normal conditions, if the power supply light is output for a short period of time (e.g., a few milliseconds) at regular intervals (e.g., every few seconds), the amount of light leaking from the fiber will not have an adverse effect on the human body, even if the first optical fiber 5 is broken.

[0017] The optical power supply / communication device 10 may generate an alarm notifying the occurrence of an abnormality and transmit the alarm to a monitoring server simultaneously with or before or after the optical power supply switching control. The alarm allows a worker to carry out work such as repairing or replacing the optical fiber cable including the first optical fiber 5 at the site. At this point, the optical power supply has already been switched to safe power supply light emission using short pulses, and recovery work by the worker is not affected. When the first optical fiber 5 or the optical fiber cable is restored at the site, the short pulses output intermittently are incident on the sensor 20, enabling the sensor 20 to operate.

[0018] The sensor 20 receives the power supply light by the intermittent emission of short pulses and resumes the transmission of the keep-alive signal. When the reception of the keep-alive signal from the sensor 20 resumes, the optical power supply / communication device 10 switches from the intermittent short-pulse power supply to normal optical power supply. As a result, normal optical power supply is automatically resumed by the optical power supply / communication device 10, and the manual task of restarting the optical power supply, which was previously performed, is no longer necessary.

[0019] Fig. 3 is a time chart of the operation of the optical power supply / communication device 10. Fig. 3(A) shows the operation of receiving from the second optical fiber 4, and (B) shows the operation of optical power supply to the first optical fiber 5. The operation of signal reception and optical power supply is shown in chronological order from left to right in Fig. 3.

[0020] The optical power supply / communication device 10 periodically receives a data signal 41 and a keep-alive signal 43 from the sensor 20. The data signal 41 includes data measured by the sensor 20, such as wind direction and speed data. The data frame width w1 of the data signal 41 depends on the number of bits of the wind direction and speed data, but is, for example, 230 microseconds. The data signal 41 is received at a constant period P1. The period P1 is, for example, 250 milliseconds.

[0021] The keep-alive signal is a short, low-power signal that indicates normal operation of the sensor 20. The pulse width w2 of the keep-alive signal is, for example, 20 nanoseconds, and the period P2 is 1 millisecond. The data signal is transmitted at the timing between the outputs of the keep-alive signal. While the optical power supply / communication device 10 receives the keep-alive signal from the sensor 20, it determines that the first optical fiber 5 is in a normal state, and performs normal optical power supply. In FIG. 3B, "H" indicates that normal optical power supply is being performed, and "L" indicates a state where no light is emitted for optical power supply. The optical power supply power in the "H" state is adjusted to, for example, 500 mW.

[0022] When an abnormality such as a break occurs in the optical fiber cable including the first optical fiber 5, the sensor 20 cannot receive optical power. When the optical power supply from the first optical fiber 5 is interrupted, the sensor 20 stops the keep-alive signal, and the optical power supply / communication device 10 stops receiving the keep-alive signal 43 from the sensor 20. When the optical power supply / communication device 10 does not receive the next keep-alive signal even after a period P1 (e.g., 250 milliseconds) has elapsed since the last keep-alive signal was received, it determines that an abnormality has occurred in the first optical fiber 5, and switches the optical power supply to intermittent emission of short pulses 45 within one second. The pulse width w3 of the short pulses 45 is, for example, 2 milliseconds, and the emission period P3 is, for example, 2 seconds. With this level of light quantity, even if the first optical fiber 5 is broken, there is no danger to the body of the worker, and safe light pulses can be output.

[0023] When the optical fiber cable is restored, the sensor 20 receives the safe short pulse 45 and resumes output of the keep-alive signal. When the optical power supply / communication device 10 resumes receiving the keep-alive signal, it switches from the intermittent short pulse power supply to normal optical power supply. This allows the optical power supply to be automatically resumed without the need for a worker to manually resume the optical power supply.

[0024] <Device configuration> FIG. 4 is a block diagram of the optical power supply / communication device 10 and the sensor 20. The optical power supply / communication device 10 includes a power source 11, an optical power transmission unit 12, an optical receiver for communication 13, a data processing unit 15, and a power supply control unit 16. The power source 11 supplies power to each component of the optical power supply / communication device 10. The optical power transmission unit 12 includes a laser light source (indicated as "LD" in the figure) 121 as a light source. The laser light source 121 is driven by a drive current from the power source 11 and outputs a power supply light. Energy is supplied to the sensor 20 by the laser light emitted from the laser light source 121. The optical power transmission unit 12 functions as an electrical-optical converter that converts electrical energy into optical energy. The laser light source 121 is, for example, a high-power semiconductor laser. It is preferable that the wavelength of the power supply light output from the laser light source 121 is separated from the wavelength of the signal light for optical communication propagating through the second optical fiber 4 (see FIG. 1) to such an extent that crosstalk does not occur.

[0025] The optical receiving unit for communication 13 receives a keep-alive signal and measurement data from the second optical fiber 4 for uplink optical communication. The optical receiving unit for communication 13 has a light receiving element such as a photodiode, and a transimpedance amplifier that converts the current output from the light receiving element into a voltage signal. When the optical receiving unit for communication 13 detects the received signal using a coherent method, it may be equipped with a local light source that outputs reference light. The optical receiving unit for communication 13 functions as an optical-electrical converter that converts an optical signal into an electrical signal.

[0026] The data processing unit 15 demodulates the analog electrical signal output from the communication optical receiving unit 13 to extract measurement data and a keep-alive signal. The data processing unit 15 may be a digital signal processor having an analog-to-digital converter (ADC) at the input stage. The measurement data extracted by the data processing unit 15 is converted into a communication format of the optical network to which a monitoring server (see FIG. 1) is connected, and transmitted to the monitoring server. The keep-alive signal extracted by the data processing unit 15 is input to the power supply control unit 16.

[0027] The power supply control unit 16 controls the power source 11 and the optical power transmitting unit 12 according to the reception state of the keep-alive signal to control the mode of optical power supply. The power supply control unit 16 may be realized by a field programmable gate array (FPGA) or other logic devices, or may be realized by using part of the functions of the digital signal processor constituting the data processing unit 15. The power supply control unit 16 determines the output pattern, output level, output start and stop timing, etc. of the power supply light based on the keep-alive signal extracted by the data processing unit 15.

[0028] When the keep-alive signal is received normally, the output level of the power supply light is set to, for example, 24 dBm. When the keep-alive signal is no longer received normally, the power supply control unit 16 controls the power source 11 and the optical power transmitting unit 12 to switch the power supply light to intermittent emission of short pulses. Alternatively, when the reception power of the keep-alive signal falls below a predetermined level, the power supply control unit 16 switches to intermittent emission of short pulses, and adjusts the intensity of the short pulses, the emission interval, etc., depending on the power state of the keep-alive signal.

[0029] The sensor 20 has an optical power receiving unit 21, an optical transmission unit for communication 23, a signal generator 25, and a detection unit 24. The optical power receiving unit 21 has a photoelectric converter 22 that converts the power supply light received by the first optical fiber 5 into electrical energy. The photoelectric converter 22 includes, for example, a photocell and a boost circuit. The photocell is a cell that utilizes the photovoltaic effect and is formed of a semiconductor having a pn junction surface. The photocell converts the incident power supply light into electrical energy. The boost circuit converts the electrical energy obtained by the photocell into a DC voltage of a desired level (DC-DC conversion). A secondary battery may be connected to the output of the photoelectric converter 22 and used as a power supply.

[0030] The electric energy generated by the optical power receiving unit 21 is supplied to the optical transmission unit for communication 23, the signal generator 25, and the detection unit 24. The detection unit 24 measures changes in the environment in which the sensor 20 is installed, as well as physical or chemical properties. In this example, the sensor 20 has a streamlined fuselage, a vertical tail, and a windmill-type propeller, and when the wind blows, the propeller rotates with the vertical tail facing downwind. The detection unit 24 detects the wind direction from the orientation of the vertical tail, and detects the wind speed from the number of rotations of the propeller. The detection results are input to the signal generator 25.

[0031] The signal generator 25 has a data signal generator 251 and a keep-alive signal generator 252. The data signal generator 251 generates a bit signal sequence representing the measurement result by the detector 24. The keep-alive signal generator 252 generates weak and short electrical pulses at set intervals. The generated electrical signal is input to the optical transmitter 23 for communication.

[0032] The optical transmitter for communication 23 has a light source such as a laser diode, and a modulator. Light incident on the modulator from the light source is modulated by a bit signal sequence and a keep-alive signal input from the signal generator 25. Any modulation method can be used. The modulated light modulated by a bit sequence representing the measurement data is output to the second optical fiber 4 as a data signal 41. A low-power keep-alive signal is output to the second optical fiber 4 at intervals shorter than the output interval of the data signal 41. The data signal and the keep-alive signal received by the optical power supply / communication device 10 are processed as described above with reference to the block diagram of the optical power supply / communication device 10.

[0033] <Optical power supply monitoring method according to the first embodiment> 5 is a flowchart of the optical power supply monitoring method of the first embodiment. This control flow is executed by the power supply control unit 16 of the optical power supply / communication device 10. When the optical power supply / communication device 10 is booted and optical power supply is started (S11), the power supply control unit 16 judges whether or not a keep-alive signal is received (S12). While the keep-alive signal is received (YES in S12), normal processing, i.e., normal optical power supply, is performed (S13). The normal optical power supply operation is, for example, continuous or long-pulse optical power supply of a constant intensity. The normal processing may include receiving measurement data, processing the data, and transferring it to a monitoring server.

[0034] If the keep-alive signal is not received (NO in S12), the power supply control unit 16 determines that an abnormality has occurred in the first optical fiber 5, and switches the optical power supply to intermittent short-pulse emission (S14). As described above, intermittent short-pulse emission is an emission of light in which very short pulses are output at regular intervals, and the amount of light emitted is not harmful to the human body. An alarm may be sent to a monitoring server in conjunction with this switching of the optical power supply. Even after switching the optical power supply, the power supply control unit 16 monitors the reception status of the keep-alive signal and determines whether the communication state has been restored (S15).

[0035] The power supply control unit 16 continues the intermittent emission of short pulses until the next keep-alive signal is received (NO in S15). When the keep-alive signal is received (YES in S15), the power supply control unit 16 determines that the first optical fiber 5 has been restored, and switches the intermittent emission of short pulses to normal optical power supply (S16). After that, the process returns to step S12, and normal processing is performed while the keep-alive signal is being received.

[0036] The control flow in Fig. 5 is repeatedly executed while the optical power supply / data acquisition device 10 is operating. As a result, even if an abnormality occurs in the first optical fiber 5 and measurement data from the sensor 20 is interrupted, optical power supply is automatically resumed when the optical fiber cable is restored, and data collection is quickly resumed. In the case of wind direction and speed measurement along a railway line, the collection of measurement data affects the safety of vehicle operation, so the optical power supply monitoring technology of the embodiment that enables early recovery of data collection is useful.

[0037] <Optical power supply monitoring method according to the second embodiment> 6 is a flowchart of an optical power supply monitoring method according to the second embodiment. In the second embodiment, the light emission timing or light emission level of the optical power supply is adjusted according to the reception state of the keep-alive signal. When optical power supply is started (S21), the power supply control unit 16 adjusts the light emission timing or light emission level of the keep-alive signal depending on the reception state ... Th1 It is determined whether the received power is equal to or lower than the first threshold P Th1 While it exceeds this limit (NO in S22), normal processing is performed (S23). That is, optical power is supplied to the sensor 20 at normal light emission power, a data signal is received from the sensor 20, and the measurement result is transferred to the monitoring server.

[0038] The reception power of the keep alive signal is equal to or lower than the first threshold P Th1 If the power of the keep-alive signal is equal to or lower than the first threshold P Th1 A second threshold P Th2It is determined whether the received power of the keep alive signal is equal to or lower than the second threshold (S25). When the received power of the keep alive signal is equal to or lower than the second threshold (YES in S25), the power supply control unit 16 adjusts the optical power supply by intermittent emission by shortening the emission interval of the short pulse intermittent emission or increasing the emission intensity (S26). However, the light amount of the intermittent emission after the adjustment is lower than the light amount during normal optical power supply, and the emission intensity is adjusted within a range not exceeding the emission intensity during normal optical power supply.

[0039] After adjusting the intermittent light emission of the short pulses, the power supply control unit 16 judges whether or not the keep-alive signal has been received normally (S27). Th1 This means that the keep-alive signal is received with a reception power exceeding the first threshold P Th21 If it does not reach this level (NO in S27), the intermittent emission of short pulses continues in the adjusted state until the keep-alive signal is received at a normal level (YES in S27). If the keep-alive signal is received normally (YES in S27), the process switches to optical power supply using normal emission (S28), and the process returns to step S22 to monitor the reception state of the keep-alive signal.

[0040] In step S25, if the reception power of the keep-alive signal is equal to or lower than the first threshold value but higher than the second threshold value (NO in S25), the process jumps to step S27, where the intermittent emission of short pulses is continued under the conditions set in step S24, and the keep-alive signal is at a normal level, i.e., the first threshold value P Th1 It is then determined whether the keep-alive signal has been received with a power exceeding this value (S28). If the keep-alive signal has been received normally (YES in S27), the process switches to optical power supply using normal light emission (S28) and returns to step S22, where the reception status of the keep-alive signal is monitored. This control is repeatedly executed during the operation of the optical power supply / communication device 10.

[0041] When the reception strength of the keep alive signal falls below the first threshold, it is highly likely that some abnormality will occur in the fiber cable. By switching to intermittent short pulse emission in advance before the fiber cable is completely disconnected and the reception of the keep alive signal stops, light leakage at a high light intensity is prevented. Meanwhile, as long as the keep alive signal is received, the sensor 20 is still operating. When the reception power of the keep alive signal falls below the second threshold, the light intensity of the short pulse intermittent emission is adjusted to a range lower than the light intensity of the normal power supply in a normal state so that the sensor 20 can obtain enough power supply light to continue operating. After that, even if the fiber cable is completely disconnected, the intermittent emission continues at a light intensity that does not adversely affect the worker. This makes it possible to automatically switch to normal optical power supply when a keep alive signal exceeding the first threshold is normally received after the optical fiber cable is restored.

[0042] According to the methods of the first and second embodiments, the optical power supply is automatically resumed when the fiber cable is restored by emitting safe light that has no effect on the human body for a short period of time when an abnormality occurs in the fiber cable without having to stop the optical power supply when the fiber cable is restored. After the repair work on the abnormal part of the fiber cable is completed, the worker does not need to manually resume the optical power supply, and the optical power supply and data communication are quickly resumed. When the target of the optical power supply is a wind direction and speed sensor along the track, the safety of vehicle operation is ensured.

[0043] Although the present disclosure has been described above based on specific examples, the present disclosure is not limited to the above configuration examples, and various modifications and application examples are possible within the scope of the present disclosure. The sensor 20 is not limited to an IoT sensor that measures natural environment such as wind direction, wind speed, temperature, and humidity, and may be a sensor that detects traffic volume and the presence of obstacles. The threshold value of the second embodiment may be set to two or more stages to adjust the amount of light emitted during an abnormality more finely. In either case, by switching from normal optical power supply to intermittent light emission of short pulses when an abnormality occurs in the fiber cable, optical power supply is automatically resumed after the fiber cable is restored, and data collection is quickly resumed.

[0044] In response to the above disclosure, the following addendum is presented: (Appendix 1) an optical power transmitting unit that optically supplies power to the sensor via a first optical fiber; an optical receiver for receiving a keep-alive signal from the sensor via a second optical fiber; a power supply control unit that switches the optical power supply by the optical power transmitting unit from normal optical power supply to short-term intermittent light emission when a reception state of the keep-alive signal changes; having When the power supply control unit receives the keep-alive signal in a normal state after switching to the short-time intermittent light emission, the power supply control unit switches the short-time intermittent light emission to the normal optical power supply. Optical power supply / communication device. (Appendix 2) the power supply control unit switches the optical power supply to the short-time intermittent light emission when the keep-alive signal is no longer received, and thereafter switches the short-time intermittent light emission to the normal optical power supply when the reception of the keep-alive signal is resumed. 2. The optical power supply / communication device according to claim 1. (Appendix 3) the power supply control unit switches the optical power supply to the short-time intermittent emission when the reception power of the keep-alive signal becomes equal to or lower than a first threshold, and adjusts the short-time intermittent emission when the reception power of the keep-alive signal becomes equal to or lower than a second threshold that is lower than the first threshold. 2. The optical power supply / communication device according to claim 1. (Appendix 4) the power supply control unit, when the reception power of the keep-alive signal becomes equal to or less than the second threshold, shortens an interval between the short-time intermittent emissions or adjusts an emission intensity within a range not exceeding an intensity of the normal optical power supply. 4. The optical power supply / communication device according to claim 3. (Appendix 5) the optical receiver receives a data signal from the sensor via the second optical fiber; a reception interval of the keep-alive signal is shorter than a reception interval of the data signal; 5. The optical power supply / communication device according to any one of appendix 1 to 4. (Appendix 6) A sensor; an optical power supply / communication device that optically supplies power to the sensor through a first optical fiber and receives measurement data and a keep-alive signal from the sensor through a second optical fiber; Including, the optical power supply / communication device switches the optical power supply via the first optical fiber from normal optical power supply to short-term intermittent emission when a reception state of the keep-alive signal changes, and after switching to the short-term intermittent emission, switches from the short-term intermittent emission to the normal optical power supply when the keep-alive signal is received from the sensor in a normal state. Optical power supply monitoring system. (Appendix 7) the sensor transmits the keep-alive signal while receiving power supply light from the optical power supply / communication device, and does not transmit the keep-alive signal when not receiving the power supply light; 7. The optical power supply monitoring system according to claim 6. (Appendix 8) In optical power supply / communication devices, A first optical fiber optically supplies power to the sensor; receiving a keep-alive signal from the sensor via a second optical fiber; when a reception state of the keep-alive signal changes, the optical power supply is switched from normal optical power supply to short-term intermittent light emission, and when the keep-alive signal is received from the sensor in a normal state after being switched to the short-term intermittent light emission, the optical power supply is switched from the short-term intermittent light emission to normal optical power supply. Optical power supply monitoring method. (Appendix 9) in the optical power supply / communication device, when the keep-alive signal is no longer received, the optical power supply is switched to the short-time intermittent light emission, and when the reception of the keep-alive signal is resumed thereafter, the short-time intermittent light emission is switched to normal optical power supply; 9. The optical power supply monitoring method according to claim 8. (Appendix 10) in the optical power supply / communication device, when the reception power of the keep-alive signal becomes equal to or lower than a first threshold, the optical power supply is switched to the short-time intermittent emission, and when the reception power of the keep-alive signal becomes equal to or lower than a second threshold that is lower than the first threshold, the short-time intermittent emission is adjusted. 10. The optical power supply monitoring method according to claim 8 or 9. (Appendix 11) In the optical power supply / monitoring device, when the reception power of the keep-alive signal becomes equal to or lower than the second threshold, the light emission interval of the short intermittent light emission is shortened, or the light emission intensity is increased within a range not exceeding the intensity during normal optical power supply. 11. The optical power supply monitoring method according to claim 10. [Explanation of symbols]

[0045] 4. Second Optical Fiber 5. The First Optical Fiber 10 Optical power supply / communication equipment 11 Power supply 12 Optical power transmission unit 121 Laser light source 13 Optical receiver for communication (optical receiver) 15 Data Processing Section 16 Power supply control section 20 Sensors 21 Optical receiving section 23 Optical transmitter for communication 24 Detection unit 25 Signal generator 251 Data signal generator 252 Keep-alive signal generator 41 Data Signal 43 Keep-Alive Signal 45 Short Pulse 100 Optical power supply monitoring system

Claims

1. an optical power transmitting unit that optically supplies power to the sensor via a first optical fiber; an optical receiver for receiving a keep-alive signal from the sensor via a second optical fiber; a power supply control unit that switches the optical power supply by the optical power transmitting unit from normal optical power supply to short-term intermittent light emission when a reception state of the keep-alive signal changes; having When the power supply control unit receives the keep-alive signal in a normal state after switching to the short-time intermittent light emission, the power supply control unit switches the short-time intermittent light emission to the normal optical power supply. Optical power supply / communication device.

2. the power supply control unit switches the optical power supply to the short-time intermittent light emission when the keep-alive signal is no longer received, and thereafter switches the short-time intermittent light emission to the normal optical power supply when the reception of the keep-alive signal is resumed.

2. The optical power supply / communication device according to claim 1.

3. The power supply control unit switches the optical power supply to the short-term intermittent emission when the received power of the keep-alive signal becomes equal to or lower than a first threshold, and adjusts the short-term intermittent emission when the received power of the keep-alive signal becomes equal to or lower than a second threshold that is lower than the first threshold.

2. The optical power supply / communication device according to claim 1.

4. the power supply control unit shortens an interval between the short-time intermittent emissions or adjusts an emission intensity within a range not exceeding an intensity of the normal optical power supply when the reception power of the keep-alive signal becomes equal to or less than the second threshold value.

4. The optical power supply / communication device according to claim 3.

5. A sensor; an optical power supply / communication device that optically supplies power to the sensor through a first optical fiber and receives measurement data and a keep-alive signal from the sensor through a second optical fiber; Including, the optical power supply / communication device switches the optical power supply via the first optical fiber from normal optical power supply to short-term intermittent light emission when a reception state of the keep-alive signal changes, and after switching to the short-term intermittent light emission, switches from the short-term intermittent light emission to the normal optical power supply when the keep-alive signal is received from the sensor in a normal state. Optical power supply monitoring system.

6. In an optical power supply / communication device, A first optical fiber optically supplies power to the sensor; receiving a keep-alive signal from the sensor over a second optical fiber; when a reception state of the keep-alive signal changes, the optical power supply is switched from normal optical power supply to short-term intermittent light emission; after switching to the short-time intermittent light emission, when the keep-alive signal is received from the sensor in a normal state, switching from the short-time intermittent light emission to normal optical power supply; Optical power supply monitoring method.

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