JP2023144633A - Contact information transmission system - Google Patents

Abstract

To provide a contact information transmission system capable of transmitting contact information by being stably operated to an electromagnetic interference such as lightning.SOLUTION: A contact information transmission system comprises: an SOG control device 10 that includes a first contact information output part 12 that outputs first contact information 11; and a local inner terminal device 20 that includes a second contact information output part 22 that outputs second contact information 21 on the basis of the first contact information. The SOG control device 10 comprises an optical signal conversion part 14 that converts the first contact information 11 into an optical signal 13, and outputs them. The optical signal 13 is transmitted to the local inner terminal device 20, and is input into the second contact information output part 22 after the conversion of them into an electric signal 26 by an optical reception signal 24. An optical wave 23 for supplying power is transmitted through an optical fiber 25 from a power supply light source 27 of the local inner terminal device 20, and the SOG control device 10 obtains a power for driving the optical signal conversion part 14 from an optical energy of the optical wave 23 for supplying power by a light reception element 16.SELECTED DRAWING: Figure 1

Description

The present invention relates to a contact information transmission system that converts contact information output from a terminal device placed outdoors into an optical signal and transmits the optical signal to a terminal device installed in a remote location such as indoors.

The SOG control device that controls the operation of the air load switch of the outdoor commercial power receiving pole, that is, the PAS (Pole Mounted Air Insulated Switch), and its attached SOG (Storage Overcurrent Ground) is connected to the customer side such as a business office. They are installed at the border with electric power companies and are used to prevent short circuits or ground faults from spreading to other areas in the event of a short circuit or ground fault occurring within a business facility. For example, if a short circuit or overcurrent accident occurs in a business facility, PAS will detect this and automatically lock the switch, temporarily cut off the power supply with the power company's circuit breaker, and then PAS will Perform operations such as operating a switch. In the case of such an accident, the SOG control device outputs contact information in order to output an alarm, and the contact information is sent to a terminal device in the office and used for controlling accident response and the like. However, in the event of a lightning strike, etc., if surge voltage or surge current is included in the contact information received by the terminal equipment in the office, it may cause malfunction or failure of the control equipment connected to the terminal equipment. .

Generally, optical signals are used to transmit information in order to cope with electromagnetic interference, lightning strikes, etc., and optical signals are also used to transmit contact information. Patent Document 1 and Patent Document 2 describe devices such as relays that convert contact signals into optical signals and transmit the optical signals.

Japanese Patent Application Publication No. 11-55223 Japanese Patent Application Publication No. 10-268990

When transmitting contact information to a terminal device installed in a remote location, such as an SOG control device, it is better to convert it into an optical signal and transmit it using an optical fiber than to transmit it using an electric cable. It is highly resistant to such obstacles. Generally, converting contact information into an optical signal requires power to generate the optical signal, and in conventional transmission devices, this power is supplied from a power source within the terminal. However, when a major electromagnetic disturbance such as a lightning strike occurs, the accompanying surge voltage may enter the optical signal generating section from the power supply, interfering with its normal operation and possibly destroying the power supply. Particularly in SOG control devices and the like that handle abnormalities, it is essential to always transmit accurate contact information without delay and error to terminals in offices, offices, etc.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a contact information transmission system that solves the above problems and operates stably even in the face of electromagnetic disturbances such as lightning strikes, and is capable of transmitting contact information.

In order to solve the above problems, in a first aspect, a contact information transmission system according to the present invention includes a first terminal device having a first contact information output section that outputs first contact information of open or short circuit of a contact. and a transmission system comprising a second terminal device having a second contact information output section that outputs second contact information based on the first contact information transmitted from the first terminal device, The first terminal device includes an optical signal converter that converts the first contact information into an optical signal and outputs it, and the optical signal is transmitted to the second terminal device via an optical fiber and converted into an electrical signal. The converted information is input to the second contact information output unit, and the second terminal device sends a light wave for power supply to the first terminal device through an optical fiber, and the optical energy of the light wave for power supply causes the It is characterized in that power is supplied to drive the optical signal converter.

As described above, in the present invention, the power of the optical signal converter for converting contact information into an optical signal is sent from the second terminal device through an optical fiber, rather than from the power supply in the first terminal device. It is obtained from the light energy of light waves. For this reason, the optical signal converter is completely separated from the power supply, and unlike conventional devices, when a major electromagnetic interference such as a lightning strike occurs, the resulting surge voltage does not enter the optical signal converter from the power supply. It can be prevented. This ensures stable operation of the optical signal converter and enables error-free transmission of contact information to the second terminal device. Furthermore, compared to using a simple battery, solar cell, or a combination of these as the power source for the optical signal converter, there is no need to monitor the amount of charge or replace the battery, and there is no need to be affected by the weather. Stable operation is possible even when there are no problems. In addition, since the optical fiber is used as a transmission path for contact information, it is possible to prevent surge voltage that reaches the first terminal device due to a lightning strike or the like from propagating to the second terminal device and destroying the second terminal device. I can do it.

Here, a semiconductor laser, a light emitting diode, etc. can be used as a light source of light waves for power supply installed in the second terminal device, and the light waves are received by a light receiving element such as a photodiode installed in the first terminal device. It is only necessary to output a light wave with a wavelength and intensity that can generate the voltage and current required by the optical signal converter. For example, it is possible to select and use light sources that are used in normal optical communications.

In a second aspect, the present invention provides the contact information transmission system according to the first aspect, wherein the optical signal converter includes a light emitting diode or a semiconductor laser, and generates the optical signal by controlling the drive current of the optical signal converter. It is characterized by output. The invention of this aspect generates an optical signal by controlling the drive current of a light emitting diode or a semiconductor laser, which is the most common means for generating an optical signal. The simplest method is to create an optical signal by controlling the drive current ON/OFF according to the open/short circuit of the contact information, convert the contact information into an electrical signal, and then create an optical signal according to the open/short circuit of the contact information. Various means are possible, such as creating a digital or analog optical signal depending on the situation. A light source for general optical communication can be used as a light emitting diode or a semiconductor laser for generating an optical signal.

In a third aspect, the present invention provides the contact information transmission system according to the first aspect, wherein the optical signal converter includes an optical switch that transmits or blocks an optical path based on an electrical signal, and the second terminal device It is characterized in that a light wave sent through an optical fiber is converted into the optical signal and outputted by controlling the optical switch. The invention of this aspect converts contact information into an electrical signal, and performs ON/OFF control of an optical switch using the electrical signal. Furthermore, in the invention of this aspect, the light source of the light wave for the optical signal is installed in the second terminal device, and the light wave sent from the second terminal device through the optical fiber is ON/OFF controlled by controlling the optical switch. to create an optical signal. Thereby, the power required for the optical signal converter can be reduced. Here, as the optical switch, various types of devices such as an optical waveguide type, a type using a mechanical mechanism, a MEMS type, etc. can be used. As the light source for generating an optical signal installed in the second terminal device, a general light source for optical communication such as a light emitting diode or a semiconductor laser can be used.

In a fourth aspect, the present invention provides the contact information transmission system according to the first aspect, wherein the optical signal converter includes a variable optical attenuator that controls the amount of transmission attenuation of the light wave by an electric signal, and the second A light wave sent from a terminal device through an optical fiber is converted into the optical signal by controlling the variable optical attenuator and output. The invention of this aspect converts contact information into an electrical signal, and controls a variable optical attenuator using the electrical signal. Also in the invention of this aspect, the light source of the light wave for the optical signal is installed in the second terminal device, and the amount of transmission attenuation of the light wave sent from the second terminal device through the optical fiber is controlled by controlling the variable optical attenuator. to create an optical signal. Thereby, the power required for the optical signal converter can be reduced. Here, various types of devices can be used as the variable optical attenuator, such as an optical waveguide type, a type using a mechanical mechanism, and a MEMS type. As the light source for generating an optical signal installed in the second terminal device, a general light source for optical communication such as a light emitting diode or a semiconductor laser can be used.

In a fifth aspect, the present invention provides a contact information transmission system according to the third aspect, in which a part of the power feeding light wave sent from the second terminal device through an optical fiber is branched to the optical switch. It is characterized in that it is converted into the optical signal and outputted under the control of. In the present aspect of the invention, when an optical signal is generated in the optical signal converter, part of the light wave for power feeding is branched and used. As a result, there is no need to install a light source for generating optical signals in the second terminal device, and there is no need to install an optical fiber that sends light waves for optical signals from the second terminal device, so the system can be improved. Simplification and cost reduction are possible. As a method for branching a part of the light wave for power feeding, an optical fiber type branching device, a micro-optics type branching device using a lens, a semi-transparent mirror, a prism, etc. can be used. The branching ratio may be designed based on the required strength of the light wave for power feeding.

In a sixth aspect, the present invention provides the contact information transmission system according to the fourth aspect, in which a part of the power feeding light wave sent from the second terminal device through the optical fiber is branched to provide the variable optical attenuation. It is characterized in that the optical signal is converted into the optical signal and outputted under control of the device. In the invention according to this aspect as well, when an optical signal is generated in the optical signal converter, a part of the light wave for power feeding is branched and used, so that a light source for generating the optical signal and a light source for sending the light wave for the optical signal are used. This eliminates the need for fibers, making it possible to simplify the system and reduce costs.

As described above, the present invention provides a contact information transmission system that operates stably even in the face of electromagnetic disturbances such as lightning strikes and can transmit contact information.

1 is a block diagram showing an example of a power supply system using a contact information transmission system according to a first embodiment of the present invention; FIG. FIG. 3 is a block configuration diagram showing an example of the configuration of an optical signal converter, an optical receiver, and an optical power supply according to the first embodiment. FIG. 3 is a block configuration diagram showing an example of the configuration of an optical signal converter, an optical receiver, and an optical power supply of a contact information transmission system according to a second embodiment. FIG. 7 is a block configuration diagram showing an example of the configuration of an optical signal converter, an optical receiver, and an optical power supply of a contact information transmission system according to a third embodiment. FIG. 7 is a block configuration diagram showing an example of the configuration of an optical signal converter, an optical receiver, and an optical power supply of a contact information transmission system according to a fourth embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the contact information transmission system of the present invention will be described in detail by way of embodiments with reference to the drawings. In addition, in the description of the drawings, the same elements are given the same reference numerals, and duplicate description thereof will be omitted.

FIG. 1 is a block diagram showing an example of a power supply system using a contact information transmission system according to a first embodiment of the present invention. In FIG. 1, the contact information transmission system of this embodiment is as follows:
The SOG control device 10 includes a SOG control device 10 that is a first terminal device and an in-office terminal device 20 that is a second terminal device, and the SOG control device 10 has a first contact information output unit 12 that outputs first contact information 11. The in-office terminal device 20 has a second contact information output section 22 that outputs second contact information 21 based on the first contact information transmitted from the SOG control device 10. The SOG control device 10 includes an optical signal converter 14 that converts the first contact information 11 into an optical signal 13 and outputs the optical signal 13, and the optical signal 13 is transmitted to the in-office terminal device 20 via an optical fiber 15. In the local terminal device 20 , the optical signal 13 is converted into an electrical signal 26 by the optical receiver 24 and input to the second contact information output section 22 . The second contact information output section 22 outputs the second contact information 21 based on the first contact information included in the electrical signal 26. Further, in this embodiment, the in-office terminal device 20 has a power feeding light source 27, and the power feeding light source 27 sends a power feeding light wave 23 to the SOG control device 10 through an optical fiber 25. The SOG control device 10 includes a light receiving element 16, receives a light wave 23 for power supply, generates a current or voltage, and obtains electric power for driving the optical signal converter 14 using the optical energy of the light wave 23 for power supply. ing. That is, power is obtained by optical power feeding from the in-office terminal device 20.

In FIG. 1, an SOG control device 10 is attached to an air load switch (PAS) 1 installed at the boundary between a power line 2 on the consumer side such as a business office and a power line 3 on the power company side that supplies electricity. It is installed to control SOG operation. If a short circuit or overcurrent accident occurs in the workplace, PAS1 will detect this and automatically lock the switch, and after temporarily cutting off the power supply with the circuit breaker on the power company side, PAS1 will switch off the switch. make it work. In the case of such an accident, the SOG control device 10 outputs first contact information 11 to output a warning based on the sensor information 4 from the PAS 1. In this embodiment, the first contact information 11 is converted into an optical signal 13 and sent to an in-office terminal device 20 in the office via an optical fiber 15, and from there the second contact information 21 is sent to the power supply control device 5. It is sent and used for control such as accident response.

In this way, since the optical fiber 15 is used as a transmission path for contact information, it is possible to prevent the surge voltage that reaches the SOG control device 10 due to a lightning strike or the like from propagating to the local terminal device 20 and destroying the local terminal device 20. I can do it. Furthermore, since the power of the optical signal converter 14 is obtained not from the power supply in the SOG control device 10 but from the optical energy of the power feeding light wave 23 sent from the local terminal device 20 through the optical fiber 25, the optical signal converter 14 is completely separated from the power supply, and in the event of a major electromagnetic disturbance such as a lightning strike, it is possible to prevent the accompanying surge voltage from entering the optical signal converter 14 from the power supply. This ensures stable operation of the optical signal converter 14, and enables transmission of contact information to the local terminal device 20 without malfunction.

FIG. 2 is a block configuration diagram showing an example of the configuration of an optical signal converter, an optical receiver, and an optical power supply according to this embodiment. FIGS. 2(a) and 2(b) show the internal configurations of the SOG control device 10 and the in-office terminal device 20, respectively. In FIG. 2A, the optical signal converter 14 includes a light emitting diode 17, and the drive circuit 18 controls the drive current of the light emitting diode 17 based on the first contact information 11 from the first contact information output unit 12. control and generate an optical signal 13. Further, the light receiving element 16 receives the light wave 23 for power supply, generates a current or voltage, and obtains electric power for driving the drive circuit 18 . In FIG. 2B, the in-office terminal device 20 is equipped with a power feeding semiconductor laser 27a as a power feeding light source, and its output light is inputted into the optical fiber 25 as a power feeding light wave 23. The optical receiver 24 also includes an O/E converter 28 and a signal processing circuit 29, and the optical signal 13 is converted into an electrical signal by the O/E converter 28, and then sent to the first contact via the signal processing circuit 29. Electrical signal 26 containing information 11 is input to second contact information output section 22 .

FIG. 3 is a block configuration diagram showing an example of the configuration of an optical signal converter, an optical receiver, and an optical power supply of a contact information transmission system according to a second embodiment of the present invention. Although illustrations are omitted, like the first embodiment, this embodiment includes an SOG control device as a first terminal device and an in-office terminal device as a second terminal device, and their basic configurations and functions is the same as in Example 1. FIGS. 3(a) and 3(b) show the internal configurations of the SOG control device and the in-office terminal device, respectively. In FIG. 3A, the optical signal converter 30 includes an optical switch 31 and a control circuit 32, and converts a light wave 34 for an optical signal sent from an in-office terminal device through an optical fiber 35 into an optical signal under the control of the optical switch 31. 36 and output. The optical switch is a device that transmits (ON) or blocks (OFF) an optical path using an electrical signal, and turns ON or OFF by the control circuit 32 based on the first contact information 11 from the first contact information output section 12. control and output an optical signal 36. The optical signal 36 is input to an optical fiber 37 and sent to an in-office terminal device. Further, the light receiving element 16 receives the light wave 23 for power supply, generates a current or voltage, and obtains electric power for driving the control circuit 32 .

As shown in FIG. 3(b), similarly to the first embodiment, the in-office terminal device includes a power supply semiconductor laser 27a as a power supply light source, and its output light is inputted into the optical fiber 25 as a power supply light wave 23. . Further, in the optical receiving section 24 , the optical signal 13 is converted into an electrical signal by an O/E converter 28 , and an electrical signal 26 is inputted to the second contact information output section 22 via a signal processing circuit 29 . However, in this embodiment, an optical signal semiconductor laser 33 for generating a light wave 34 for an optical signal is provided, and its output light is sent as the light wave 34 for an optical signal to the SOG control device via an optical fiber 35.

In this embodiment as well, since the optical fiber 37 is used as a transmission path for contact information, it is possible to prevent surge voltage caused by lightning strikes etc. from propagating to the terminal equipment in the office. Since the optical signal converter 30 is obtained from the optical energy of the light wave 23, the optical signal converter 30 is completely separated from the power source, ensuring stable operation of the optical signal converter 30, and making it possible to transmit contact information without malfunction.

As the optical switch used in this embodiment, various types of devices such as an optical waveguide type and a MEMS type can be used, but an optical switch that is highly reliable and can be driven with low power is desirable.

FIG. 4 is a block configuration diagram showing an example of the configuration of an optical signal converter, an optical receiver, and an optical power supply of a contact information transmission system according to a third embodiment of the present invention. Although illustrations are omitted, like the first embodiment, this embodiment includes an SOG control device as a first terminal device and an in-office terminal device as a second terminal device, and their basic configurations and functions is the same as in Example 1. FIGS. 4A and 4B show the internal configurations of the SOG control device and the in-office terminal device, respectively.

As shown in FIG. 4A, this embodiment includes an optical fiber splitter 44, and the optical signal converter 40 includes a variable optical attenuator 41 and a control circuit . A light wave 43 for power supply sent from an in-office terminal device through an optical fiber 45 is branched by an optical fiber splitter 44 into a light wave 43a for power supply and a light wave 43b for an optical signal. A light wave 43b for an optical signal is input to a variable optical attenuator 41, converted into an optical signal 46, and output. The variable optical attenuator 41 is a device that controls the amount of transmission attenuation of light waves using an electric signal, and the amount of attenuation is controlled by the control circuit 42 based on the first contact information 11 from the first contact information output section 12. An optical signal 46 is output. The optical signal 46 is input to an optical fiber 47 and sent to an in-office terminal device. Further, the light receiving element 16 receives the light wave 43a for power supply, generates a current or voltage, and obtains electric power for driving the control circuit 42.

As shown in FIG. 3(b), similarly to the first embodiment, the in-office terminal device is equipped with a power feeding semiconductor laser 42 as a power feeding light source, and its output light is input into an optical fiber 45 as a power feeding light wave 43. . In the case of this embodiment, a part of the light wave 43 for power feeding is used as the light wave 43b for an optical signal, and therefore has an intensity that includes that part. In the optical receiving section 24 , the optical signal 13 is converted into an electrical signal by an O/E converter 28 , and the electrical signal 26 is inputted to the second contact information output section 22 via a signal processing circuit 29 .

In this embodiment as well, it is possible to prevent surge voltages caused by lightning strikes and the like from propagating to the in-office terminal equipment, and the optical signal converter 40 is completely separated from the power supply, ensuring stable operation of the optical signal converter 40. , it becomes possible to transmit contact information without malfunction. As the variable optical attenuator used in this embodiment, various types of devices such as an optical waveguide type and a MEMS type can be used, but a variable optical attenuator that is highly reliable and can be driven with low power is desirable.

FIG. 5 is a block configuration diagram showing an example of the configuration of an optical signal converter, an optical receiver, and an optical power supply of a contact information transmission system according to a fourth embodiment of the present invention. Although illustrations are omitted, like the first embodiment, this embodiment includes an SOG control device that is a first terminal device and an in-office terminal device that is a second terminal device, and their basic configuration and basics. The functions are similar to those in the first embodiment. However, the contact information transmission system of this embodiment is different in that four types of contact information are transmitted. FIGS. 5A and 5B show the internal configurations of the SOG control device and the in-office terminal device, respectively.

In FIG. 5A, the optical signal converter 50 includes four variable optical attenuators 51a, 51b, 51c, and 51d, four control circuits 52a, 52b, 52c, and 52d, and further includes an optical fiber splitter. 54, and a 1×4 optical fiber splitter 58. First, a light wave 53 for power supply sent from an in-office terminal device through an optical fiber 55 is branched by an optical fiber splitter 54 into a light wave 53a for power supply and a light wave 53b for an optical signal. Furthermore, the light wave 53b for the optical signal is branched into four light waves 56a, 56b, 56c, and 56d for the optical signal by the 1×4 optical fiber splitter 58, and the light waves 53b for the optical signal are split into four light waves 56a, 56b, 56c, and 56d for the optical signal, respectively. input. Those four light waves are attenuated by control circuits 52a, 52b, 52c, and 52d, respectively, based on the four pieces of first contact information 11a, 11b, 11c, and 11d from the first contact information output unit 60. and outputs optical signals 57a, 57b, 57c, and 57d. These four optical signals are input into optical fibers 59a, 59b, 59c, and 59d, respectively, and sent to the in-office terminal equipment. Further, the light receiving element 61 receives the light wave 53a for power supply and generates a current or voltage to obtain electric power for driving the four control circuits 52a, 52b, 52c, and 52d.

As shown in FIG. 5(b), the in-office terminal device includes a power feeding semiconductor laser 62 as a power feeding light source, and its output light is inputted into an optical fiber 55 as a power feeding light wave 53. In the case of this embodiment, a part of the power feeding light wave 53 is used as a light wave for four optical signals, and therefore has an intensity including that amount. In the optical receiver 63, the optical signals 57a, 57b, 57c, and 57d sent through the four optical fibers are converted into electrical signals by the O/E converters 28a, 28b, 28c, and 28d, respectively, and the optical signals are sent to the four signal processing circuits. Four electrical signals 26a, 26b, 26c, and 26d including first contact information 11a, 11b, 11c, and 11d, respectively, are sent to the second contact information output section 64 via 29a, 29b, 29c, and 29d, respectively. is input. The second contact information output section 64 outputs four contact information.

In this embodiment as well, it is possible to prevent surge voltage caused by lightning strikes etc. from propagating to the terminal equipment in the office, and the optical signal converter 50 is completely separated from the power supply, ensuring stable operation of the optical signal converter 50. , it becomes possible to transmit contact information without malfunction.

It goes without saying that the present invention is not limited to the above embodiments, and various modifications can be made depending on the purpose. For example, the number of contact information to be transmitted can be arbitrarily set according to system requirements, and the configurations of the optical signal converter, optical receiver, optical power supply section, light receiver, etc. may be designed according to the number of contact information. Further, the first terminal device and the second terminal device can be provided with components, electric circuits, etc. other than those shown in the embodiments, as necessary.

1 PAS
2, 3 Power line 4 Sensor information 5 Power control device
10 SOG control device 11, 11a, 11b, 11c, 11d First contact information 12, 60 First contact information output unit
13, 36, 46, 57a, 57b, 57c, 57d Optical signal 14, 30, 40, 50 Optical signal converter 15, 25, 35, 37, 45, 47, 55, 59a, 59b, 59c, 59d Optical fiber 16 , 61 light receiving element 17 light emitting diode 18 drive circuit 20 local terminal device 21 second contact information 22, 64 second contact information output unit 23, 43, 43a, 53, 53a light wave for power supply 24, 63 optical receiver 26 , 26a, 26b, 26c, 26d Electric signal 27 Power supply light source 27a, 42, 62 Power supply semiconductor laser 28, 28a, 28b, 28c, 28d O/E converter 29, 29a, 29b, 29c, 29d Signal processing circuit 31 Optical switch 32, 42, 52a, 52b, 52c, 52d Control circuit 33 Semiconductor laser for optical signal 34, 43b, 53b, 56a, 56b, 56c, 56d Light wave for optical signal 41, 51a, 51b, 51c, 51d Variable light Attenuator 44, 54 Optical fiber splitter 58 1×4 optical fiber splitter

Claims (6)

a first terminal device having a first contact information output section that outputs first contact information indicating whether a contact is open or short-circuited; In a transmission system including a second terminal device having a second contact information output unit that outputs contact information of two points,
The first terminal device includes an optical signal converter that converts the first contact information into an optical signal and outputs it, and the optical signal is transmitted to the second terminal device via an optical fiber and converted into an electrical signal. converted and input to the second contact information output section,
A contact information transmission system characterized in that power for driving the optical signal converter is supplied as optical energy from the second terminal device to the first terminal device through an optical fiber. 2. The contact information transmission system according to claim 1, wherein the optical signal converter includes a light emitting diode or a semiconductor laser, and generates and outputs the optical signal by controlling a driving current thereof. The optical signal converter includes an optical switch that transmits or blocks an optical path according to an electric signal, and converts a light wave sent from the second terminal device through an optical fiber into the optical signal under control of the optical switch. The contact information transmission system according to claim 1, wherein the contact information transmission system outputs the contact information. The optical signal converter includes a variable optical attenuator that controls the amount of transmission attenuation of the light wave by an electrical signal, and the optical signal converter is configured to convert the light wave sent from the second terminal device through the optical fiber into the optical signal by controlling the variable optical attenuator. The contact information transmission system according to claim 1, wherein the contact information transmission system converts into a signal and outputs the signal. Contact point information transmission according to claim 3, characterized in that a light wave for power feeding sent from the second terminal device through an optical fiber is branched and converted into the optical signal under control of the optical switch and output. system. 5. The contact point according to claim 4, wherein a light wave for power feeding sent from the second terminal device through an optical fiber is branched and converted into the optical signal under control of the variable optical attenuator and output. Information transmission system.