JPS6333812B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an optical branching device for branching optical information from a network main line to each terminal in a digital information network system using optical fiber cables.

[Technical background of the invention and its problems]

Conventionally, coaxial cables have been used as network lines in digital information network systems, but in recent years, optical fiber cables have been attracting attention. One of the reasons for this is that the cable is not affected by external noise.

However, when configuring a network using optical fiber cables, there is a problem in that branching light from the network main line (bus) to each terminal becomes technically difficult. Conventionally, two-way separation using prisms or half mirrors and wavelength separation using diffraction gratings have been known for splitting light, but since these are optical separations, the amount of light is attenuated significantly, making it difficult to actually split a large number of branches. Therefore, it cannot be used in digital information network systems.

Another technique, as shown in FIG. 1, is to convert optical information sent through an optical fiber cable 1 into an electrical signal using a light-receiving element, for example, a phototransistor 2, and send it to a terminal 3. The electric signal is immediately converted into an optical signal by a light emitting element, for example, an LED 5, and sent to the network main line 4, and the information from the terminal 3 is transmitted to the network main line 6 via a logic circuit 6 and an LED 5. An optical splitter that sends out Further, as described in Japanese Patent Application Laid-Open No. 52-17837, a T-type optical branching device is already known, which outputs an optical signal inputted to one terminal to the other two terminals. However, such an optical branching device has a drawback in that it cannot detect whether the information sent from the terminal 3 collides with the information sent from another terminal.

In order to solve this problem, the inventor of the present invention previously proposed an optical splitter as shown in FIG. That is, this optical branching device includes first and second photoelectric conversion elements 17 that convert optical information supplied from the first direction and the second direction of the main network line via optical fibers 11 and 13, respectively, into electrical signals. and 19, and a third photoelectric conversion element 21 that converts optical information supplied from the terminal via the optical fiber 15 into an electrical signal, and transmits the information converted into the electrical signal to the first and electro-optical conversion elements 18 and 20 for sending out via the optical fibers 12 and 14 in the second direction, and a third electro-optic converting element 22 for sending out via the optical fiber 16 to the terminal, And each electric signal obtained by the first to third photoelectric conversion elements 17, 19, 21 is transmitted to the first to third electro-optical conversion elements 18, 2.
Logic circuit 23 so that it is supplied to all of 0 and 22.
It is constructed by

However, in this optical splitter, optical-electrical
Although effective when the electro-optical converter operates at high speeds, serious problems arise at low speeds. When a large number of turnouts are used, the turnout that starts transmitting the signal from the turnout in series drives the next turnout, and the re-transmission signal from that turnout returns to the turnout that originally sent the signal. . There is no problem if the delay time for the return is zero, but in reality there is always a delay, so
Since this signal is transmitted to all the branchers and returned to the receiver at the terminal of the brancher that originally sent the signal, a distorted signal is sent due to the delay even though it is the same signal, resulting in optical-electrical and electrical-optical conversion. If the response of the device is slow, it will be treated as a collision even if no collision has occurred, and in the worst case, it will receive erroneous data.

[Purpose of the invention]

The present invention has been made in view of the above-mentioned points, and makes it possible to configure a bus-type network by pairing two optical fiber cables.
Another object of the present invention is to provide an optical branching device that prevents erroneous reception due to delay in the branching device, and enables a sending terminal to simultaneously detect collisions and network conditions.

[Summary of the invention]

In the present invention, optical information sent from a terminal device via an optical fiber is sent out via the optical fiber in two different directions on the network main line, and at the same time is returned to the terminal device. If optical information is sent from the second (or second) direction, it is sent to the second (or first) direction of the terminal equipment and network main line, but it is not returned to the first (or second) direction. This is how it was done.

〔Effect of the invention〕

According to the configuration of the present invention, even if a large number of optical branching devices are connected in series to form a network, there is no feedback of the same information, so that delays in the branching devices do not directly result in data errors. As long as the collision detection is not transmitted by another terminal, false collision detection cannot occur. Also, since collisions come from the optical cable in the opposite direction to the direction in which the branch is flowing, collision detection is fully possible on the terminal side.

[Embodiments of the invention]

Hereinafter, the present invention will be explained in detail with reference to the drawings. FIG. 3 is a block diagram showing an embodiment of the optical branching device of the present invention. The same parts as in FIG. 2 are given the same numbers. In the figure, 10 is an optical branching device of the present invention, and 11, 12, 13, 14, 15, and 16 are optical fibers. The optical fibers 11 to 16 are a pair of two fibers that transmit optical information in opposite directions. For example, an optical fiber 11 transmits information from the left side to the right side in the figure as shown by the arrow.
and an optical fiber 12 that transmits information in the opposite direction. Similarly, optical fibers 13 and 14 and 15 and 16 are paired.

The optical splitter 10 connects these optical fibers 11 to 16.
Among the optical fibers 11, 13 and 15 that supply optical information to the optical splitter 10, there are photoelectric conversion elements 17, 19 and 21 such as photodiodes and phototransistors that convert the optical information into electrical signals. Also, optical fibers 12, 14 and 1 transmit optical information from the optical splitter 10 to the outside.
6, an electro-optical conversion element 18, such as a light emitting diode (LED), which converts an electrical signal into optical information,
20 and 22. The outputs of the photoelectric conversion elements 17 and 21 are input to and supplied to a logic (OR) circuit 24 . The output of the OR circuit 24 is supplied to the electro-optical conversion element 20. Further, the outputs of the photoelectric conversion elements 19 and 21 are supplied to an OR circuit 25 as inputs. The output of the OR circuit 25 is supplied to the electro-optical conversion element 18. Furthermore, the outputs of the photoelectric conversion elements 17, 19, and 21 are supplied to an OR circuit 26 as inputs. The output of the OR circuit 26 is supplied to the electro-optical conversion element 22. Although not shown, the photoelectric conversion element 1
7, 19, 21, electro-optical conversion element 18, 20, 22
A voltage +V is applied to the OR circuits 24, 25, and 26 from the power supply circuit.

According to the optical branching device having the above configuration, when information is sent from the terminal via the optical fiber 15, the information is converted into an electrical signal by the photoelectric conversion element 21, and the OR circuits 24, 25, 26
It is supplied to electro-optical conversion elements 18, 20 and 22 via. And these electro-optical conversion elements 18, 20
and 22, it is converted back into optical information and placed on the optical fibers 12, 14 and 16. That is, the optical information from the optical fiber 15 is branched into two different directions of the network main line by this optical branching device, and at the same time is returned to the information source via the optical fiber 16.

On the other hand, when optical information is sent from one direction of the main network line, for example from the left side in the figure, via the optical fiber 11, this optical information is converted into an electrical signal by the photoelectric conversion element 17, and then sent via the OR circuit 24. and is supplied to the electro-optical conversion element 20 and to the electro-optic conversion element 22 via the OR circuit 26, respectively. The electro-optical conversion elements 20 and 22 convert the information into optical information again, and the optical information is transmitted through the optical fibers 14 and 1, respectively.
6. Similarly, optical information sent from the right side of the network main line through the optical fiber is converted into an electrical signal by the photoelectric conversion element 19, and then sent to the electro-optic conversion element 18 via the OR circuit 25, and then to the OR circuit. They are respectively supplied to the electro-optical conversion elements 22 via 26. The information is then converted back into optical information and sent to the network main line and terminal equipment via the optical fibers 12 and 16, respectively.

That is, as is clear from the above description, when optical information is sent from a terminal device, the optical branching device of the present invention branches the optical information into three branches, one in two different directions of the main network line and the other as the information transmission source. However, if the optical information is sent from one direction of the network main line, the optical information is simply branched to the other direction of the network main line and towards the terminal. It operates in such a way that it does not return. Therefore, according to the optical branching device of the present invention, even when a network is constructed by tangentially connecting many optical branching devices in series, there is no feedback of the same information, so the delay of information in the optical branching device is linear. This does not result in data errors and enables accurate transmission of optical information. In addition, the information sent from the terminal is immediately returned to the terminal that sent it and is monitored, making it easy to detect the state of the line, especially whether there is a collision with other optical information. .

Furthermore, unlike optical branching using a prism, half mirror, or diffraction grating, the optical branching device of the present invention causes no optical loss, so there is no problem even if a large number of them are installed on a network.

FIG. 4 shows an external perspective view of the optical splitter of the present invention, in which a photoelectric conversion element 1 is mounted on a chassis 30.
7, 19, 21, electro-optical conversion element 18, 20, 2
2. A logic circuit 23 and a stabilized power supply circuit 31 are arranged. The photoelectric conversion device and the electro-optical conversion device include a connection terminal 32 for connecting to an optical fiber.
is provided. In addition, the stabilized power supply circuit 31
An AC outlet plug 33 is integrally provided, and a voltage of AC 100V is applied to the stabilized power supply circuit 31 via this plug 33.

Moreover, FIG. 5 shows a case in which a storage battery (Ni-Cd) 41 and a solar cell 42 are used in combination instead of using an AC power source as a power source for supplying power to the photoelectric conversion element, the electro-optical conversion element, and the logic circuit. There is no need to supply power to the optical splitter 10 from the outside, and no electrical wiring is required.

FIG. 6 shows an example in which the optical branching device 10 of the present invention is applied to an optical fiber communication line. 6 in the diagram
1, 62, and 63 are optical splitters of the present invention. Further, 64, 65, and 66 are various terminals connected thereto, and 67 is an optical cable. In the diagram, terminal 6
The flow of information when No. 5 is the source is shown by solid arrows. This shows how the caller monitors the line status and transmits information. Now, if the terminal device 64 starts oscillating at the same time as the terminal device 65 starts transmitting, the flow of information will be as shown by the dotted arrow, and the two pieces of information will be in a state of being mixed with each other, and the terminal device will be able to By detecting this, it is possible to know about information conflicts.

[Brief explanation of the drawing]

Figure 1 shows an example of a conventional optical splitter, Figure 2 shows an example of a conventional optical splitter.
The figure shows an example of an improved optical splitter, FIG. 3 is a block diagram showing the configuration of an embodiment of the optical splitter of the present invention, and FIGS. 4 and 5 each show an example of the embodiment of the invention. FIG. 6, an external view of the optical branching device, is a diagram showing an example in which the optical branching device of the present invention is applied to an optical fiber communication line. 10... Optical splitter, 11-16... Optical fiber, 17, 19, 21... Photoelectric conversion element, 18,
20, 22...Electronic conversion element, 24, 25, 26
...OR circuit, 28...Stabilized power supply circuit, 41
...Storage battery, 42...Solar battery.

Claims (1)

[Claims] 1. First and second photoelectric conversion means that convert optical information sent through optical fibers from different directions of the network main line into electrical signals, and convert optical information sent from terminal equipment into electrical signals. a third photoelectric conversion means; first and second converting means for converting an electrical signal into an optical signal and transmitting the optical signal through an optical fiber in a direction opposite to the direction in which the optical information is transmitted of the network main line; an electro-optical conversion means, a third electro-optical conversion means for converting an electrical signal into an optical signal and sending it to the terminal device, and an output of the first photo-electric conversion means to the second and third electro-optical conversion means; a logic circuit that supplies the output of the second photoelectric conversion means to the first and third electro-optical conversion means, and further supplies the output of the third photoelectric conversion means to the first to third electro-optical conversion means, respectively; An optical splitter characterized by comprising: