JPS58172039A - Optical transmission system - Google Patents

Abstract

PURPOSE:To improve the reliability of a system, by powering on a photoelectric converter on a master station side from a master station device and photoelectric converters on respective terminal sides from corresponding terminal devices. CONSTITUTION:The photoelectric converter 3a on the side of the master station device 1 is supplied with electric power from the master station device 1 by a power source connection 32. The photoelectric converters 3b on the sides of the terminal devices 2 are supplied with electric power from the terminal devices 2 by electric connections 36. Consequently, transmission lines extending to the photoelectric converters 3b of the terminal devices 2 are ready for communication as far as the master station device 10 is powered on, and the operation of the total system is not influenced by the power-on state of a terminal device 2.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an optical transmission system, and more particularly, to an optical transmission system applied to a local communication network that connects a central main station device such as a central processing system and an intelligent terminal device such as an office computer. Traditionally, local networks have been Eth, in which an electrical signal bus using coaxial cables is shared equally between each communication terminal.
ernet (Japanese Unexamined Patent Publication No. 51-11804), or Fibernet (for example, Unexamined Japanese Patent Application No. 53-102
763), etc., are known.

There is a coaxial/optical fiber combined transmission system in which a coaxial cable is used as the main transmission path, and each terminal device is connected via a photoelectric converter from a tag disposed in the middle to an optical fiber transmission path as a branch transmission path. In this method, each terminal device is equal to each other and no specific terminal device is configured as the main station, so it is possible to install a separate power supply for each photoelectric converter and constantly supply power to each party power converter. is necessary. In order to reduce the number of photoelectric converters, there are examples in which a sgelitter and a combiner are used in the photoelectric interface section. This involves forming multiple-to-single fiber connections through special optical fiber configurations, but is technically and economically difficult. Therefore, even when the number of terminals installed is small, such as when the system is first introduced, it is necessary to use complicated and expensive sugeritters and combiners.

Connect the terminal device to multiple intermediate taps of the coaxial cable,
Among the methods in which each terminal device shares a coaxial cable as a common transmission path, there is a method in which one specific terminal device is treated as a master station for handling calls. For example, the main station may be a large computer system at a center, and the other terminals may be office computers. Such local networks are often installed in the normal environment of the user's premises, and when designing them, poor external conditions with respect to noise etc. are assumed, such as in the case of data highways installed in factories. Must.

In order to protect the system from such harsh external conditions such as noise and also to improve the data transmission speed, it is advantageous to use optical fibers as transmission lines instead of coaxial cables.

Optical fiber transmission lines are also required to be as easy to handle as coaxial cable transmission lines and to have a price/performance ratio.

For example, special configurations such as sgelitters and combiners as optical fibers and photoelectric converters must be avoided. When an optical fiber is branched and connected in order to share an optical fiber transmission line among a plurality of terminal devices, a considerable amount of optical energy is lost in the branched connection. In order to compensate for such branching losses, if the optical fiber transmission line is configured so that it is converted into an electrical signal and then relayed and branched at each relay point, the reliability of the power supply for each relay device will be improved throughout the system. This will affect the reliability of the That is, if a power failure occurs in one of such relay devices, the entire network becomes unable to communicate. In addition, even if the initial capacity of the number of terminal devices connected to the main station device is very small compared to the final capacity, the system can be operated economically, and the subsequent addition of terminal devices does not significantly change the entire system. It is desirable to be able to do this easily without having to worry about it.

It is an object of the present invention to eliminate such drawbacks of the prior art and provide an optical transmission system with high reliability and expandability.

Another object of the present invention is to provide an optical transmission system that is easy to handle and has a price/performance ratio that is compatible with the coaxial cable system.

These objects are achieved by the optical transmission system according to the invention as follows. In other words, this system is connected to an optical fiber/J transmission line and one end of the optical fiber transmission line, converts an electrical signal into an optical signal, transmits it to the optical fiber transmission line, and receives it from the optical fiber transmission line. A first photoelectric converter that converts an optical signal into an electrical signal is connected between the other end of the optical fiber transmission line and the slave device, and converts the electrical signal from the slave device into an optical signal and converts it into an optical fiber. a second photoelectric converter that transmits the optical signal to the transmission line and converts the optical signal received from the optical fiber transmission line into an electrical signal and sends it to the slave station device, the first photoelectric converter being common to the main station device. By connecting and transferring electrical signals between the main station device and the first photoelectric converter, mutual communication between the main station device and the slave device is enabled, and the first photoelectric converter From the station equipment,
The second photoelectric converters are each supplied with power from the corresponding slave station devices.

Next, embodiments of the optical transmission system according to the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a block diagram showing the basic concept of the present invention.

In the figure, n slave stations, ie, terminal devices 2, such as intelligent terminals, are connected to a master station L installed in a center such as a central processing system (n is a natural number) to form a local communication network. .

Mutual connection is made by optical fiber transmission line 3 via photoelectric converters 3a and 3b. The connection between the main station device 1 and the photoelectric converter 3a is such that an information signal is transmitted through an electrical connection 30, and a power supply connection 32 is used to transmit information signals between the main station device 1 and the photoelectric converter 3a.
Power is supplied from the photoelectric converter 3a to the photoelectric converter 3a. According to the present invention, these electrical connections 30 and 32 do not imply physical cable connections, as described below.

The photoelectric converter 3b on the terminal side is electrically connected to the terminal device 2 34
・Transmission of information signals is performed. Further, power is supplied to the photoelectric converter 3b from the corresponding terminal device 2 via the power supply connection 36.

Information transmitted from the main station device 1 to each terminal device 2 is sent as an electrical signal to each photoelectric converter 3a via an electrical connection 30, where it is converted into an optical signal. This optical signal propagates through each optical fiber transmission line 3 and is transferred to a corresponding remote photoelectric converter 3b, where it is converted back into an electrical signal.

This information is sent as an electrical signal via the electrical connection 34 to the corresponding terminal device 2. In this way, the main station device 1
Information transmitted from can reach all terminal devices 2 within this network.

Information transmitted from one terminal device 2 is sent to the photoelectric converter 3b.
The signal is converted into an optical signal at the optical fiber transmission line 3 and reaches the main station side photoelectric converter 3a. Here, it is again converted into an electrical signal and sent via the electrical connection 30 to the photoelectric converter 3a corresponding to the main station device 1 and other terminals. The information sent to the other photoelectric converters 3a will be reconverted into optical signals there and transferred to all other terminal devices 2.

Power for the main station side photoelectric converter 3a is supplied from the main station device 1 through the power supply connection 33, so as long as the power is turned on to the main station device l, all the photoelectric converters 3a on the main station side
is powered and ready for operation. On the other hand, the photoelectric converter 3b on the terminal side receives power supply from the corresponding individual terminal device 2. Therefore, regardless of the power-on state of each terminal device 3, as long as the main station device 1 is powered on, the entire network is in a communicable state.

FIG. 2 is a block diagram showing a specific configuration of the optical transmission system shown in FIG. 1. Elements similar to FIG. 1 are designated by the same reference numerals. In the figure, the optical fiber transmission line 3 consists of two optical fibers 10G and 102, forming one optical fiber cable. Photoelectric converters 3a and 3b are connected to both ends of the cable 30, and the pair of photoelectric converters 3a and 3b and the cable 3 constitute one connection module.

The main station side photoelectric converter 3a has a receiver 3ar and a transmitter 3at connected to an electrical connection 30, and the receiver 3ar is connected to an electrical-to-optical (Elo) converter 104.
The transmitters 3at are each connected to an optical/electrical converter 106.

E10 converter 104 connects optical fiber 100 to still 0/F
, transducer 106 are each coupled to optical fiber 102.

The photoelectric converter 3a has signal terminals 381 and 3 as shown in the figure.
s2, and the signal terminal 3sl is the signal terminal 1 of the main station device 1.
s or other photoelectric converter 3a to establish continuity of the electrical connection 30 from the master station l to each photoelectric converter 3a. Similarly, the power terminals 3pl and 3gl of the photoelectric converter 3a are mechanically engaged with the power terminals 1p and 1g of the main station l, respectively, or the power terminals 3p2 and 3g2 of the other photoelectric converter 3a.
and establish continuity of the power supply connection 32 from the main station device 1 to each photoelectric converter 3a. That is, each photoelectric converter 3a constitutes a stack module that can be connected to the main station device l as many times as necessary by mechanically engaging the respective terminals with each other. Therefore, inside the main station device 1, the electrical connection 30 is connected to the transmitter 1t and the receiver 1r, and the power supply connection 32 is connected to the transmitter 1t and the receiver 1r, and the power supply connection 32 is connected to the transmitter 1t and the receiver 1r.
and earth GND, it is possible to mutually transfer information between all the photoelectric converters 3a and the main station device l via the electrical connection 30, and also to connect all the photoelectric converters 3a to Power can be supplied from the main station device 1.

On the other hand, the terminal device 2 is connected to the optical cable 3 by a terminal-side photoelectric converter 3b. The photoelectric converter 3b has an O/E converter 108 and an E10 converter 11G, and the O/E converter 108 is an optical fiber/? At 100, an E10 converter 110 is coupled to an optical fiber 1Gm. C converter 108
The electrical output of is connected to transmitter 3bt and E1
The electrical input of the 0 converter 11O is connected to the receiver 3br. The transmitter 3bt is connected to the receiver 2r of the terminal device 2, and the receiver 3br is connected to the transmitter 2t of the terminal device 2, and both connections constitute the electrical connection 34 in FIG. 1. Photoelectric converter 3b is connected to power supply 3
From the terminal device 2 via b, for example +5 volts +5v
and receives power supply from Earth's Ground. in this way,
The photoelectric converter 3b is also configured to be mechanically attachable to and detachable from the terminal device 2, and establishes an electrical connection between the two.

Transmission data T1 from the main station device l is sent to the transmitter 1
t to the signal terminal IS. This signal is transmitted via electrical connection 30 to each photoelectric converter 3a and received by receiver 3ar'. So E10 converter 1
04 is driven and transmitted as an optical signal into the optical cable 3 toward the corresponding terminal device 2. The data signal converted into an electrical signal by the O/E converter 108 in the photoelectric converter 3b is sent to the corresponding terminal device 2 by the transmitter 3bt and processed as data R2. This operation applies to all terminal devices 2 connected to the main station device 1.
Each terminal device 2 identifies whether the received data is addressed to its own station or not based on the address information included in the received data.

Transmission data T2 from the terminal device 2 is transmitted by the receiver 3br in the photoelectric converter 3b, and is sent to the E10 converter 110.
to drive. The data thus converted into an optical signal is transmitted to the corresponding photoelectric converter 3a through the optical cable 3 and converted into an electrical signal. This signal is sent by the transmitter 3at to the electrical connection 30 and is sent to the signal terminal 1
The signal is received by the receiver 1r of the main station device l via the signal s, and is also received by the receivers 3ar of all the photoelectric converters 3a connected thereto. The main station device l that received this data as received data R1 processes it, and all other terminal devices 2 transmit this data to the corresponding receivers 3 ar and E10 converters 1, respectively.
04, optical fiber 100.0β converter 108)) By receiving the signal through the transmitter 3bt and receiver 2r', it is possible to detect that the line of the local network is currently in use, that is, the line is busy. Furthermore, when multiple terminal devices 2 start transmitting data at the same time, electrical signals based on the data transmitted by these terminal devices 2 are combined on the electrical connection 30 and sent to all the terminal devices 2. Therefore, each terminal device 2 can detect transmission collisions on the line.

3 and 4 show other embodiments of the optical transmission system according to the invention, in which similar components to the embodiment of FIG. 2 are designated with the same reference numerals.

In the embodiment of FIG. 3, the electrical connection 30 is separated for transmission and reception, and the electrical connection 30 is comprised of 30t and 30r. Therefore receiver 3ar and E10 converter 104 and transceiver 3at and O/E converter 10
Since the two systems of 6 can be configured independently of each other,
The photoelectric converter 3a on the main station side may have exactly the same configuration as the photoelectric converter 3b on the terminal side. This means that the main station device 1 and the terminal device 2
In the cable connection work to connect the photoelectric converter 3a
Necessary power to distinguish between and 3b (meaning no, moji-
This simplifies the design and manufacturing process of the
Facility construction will also be simplified.

FIG. 4 shows the transmission line 30t and reception line 30r of the electrical connection 30.
constitutes a loop line. As in Figure 3,
Although only two photoelectric converters 3a are shown in FIG. 4 to simplify the drawing, it is of course possible to connect any number of photoelectric converters 3a in cascade. The above-mentioned loop line is formed by mutually coupling the transmission/reception line Set of the photoelectric converter 3a at the final stage of the connection stack and the 30r signal terminals 38t2 and 38r2 with the loop line 200. As a result, in the interface circuit with the photoelectric converter 3a of the main station device 1, the transmitting and receiving sides can be completely separated from each other, as shown in the figure. It can be seen from the figure that this is exactly the same configuration as the interface circuit with the photoelectric converter 3b of the terminal device 2.

In the embodiment shown in FIG. 2, the interface circuit for the photoelectric converter 3b of the terminal device 2 uses the output of the transmitter 2t and the input of the register 2r in common, in other words, the output of the transmitter 3bt and the input of the register 2r. 3b
It is also possible to configure the two electrical connections 34 to be a single one with the r input in common. That is, the interface circuit configured in this manner can have exactly the same configuration as the interface circuit with the photoelectric converter 3a of the main station device l. By doing so, the electrical connection 30 of the photoelectric converter 3a and the electrical connection 3 of the photoelectric converter 3b are unified.
4, and the transmitted signal may loop back to the receiving side and cause oscillation. In order to prevent this, both photoelectric converters 3a and 3b are each provided with a transmission direction switching circuit as shown in FIG. Furthermore, the fifth
Although the figure shows a case in which such a transmission direction switching circuit is provided in the photoelectric converter 3a, it is needless to say that the structure will be exactly the same if it is provided in the photoelectric converter 3b.

The transmission direction switching circuit in FIG. 5 includes a two-man NAND dart as a transmitter 3at, an inverter as a receiver 3ar, an OA converter 106, and an E10 converter 1.
NAND gate 2 connected as shown between 04 and 04
00 and 201. Inverter 204.2 human power N'AN
Dr-to 206 and capacitors 208 and 21
Consists of G.

NAND gates 200 and 202 form a flip-flop in which the driving state of one signal line 212 or 214 prevents the signal state of the other signal line 214 or 212 from being output to optical fiber 100 or electrical connection 30. The NAND key (20g or 3at) is controlled so as to Capacitors 208 and 210 are delay circuits that compensate for circuit propagation delay time when the corresponding signal lines 214 and 212 are in a non-driven state.

If this transmission direction switching circuit is provided in both the photoelectric converters 3a and 3b, for example, the leopard converter 10 in FIG.
4 is transmitting a data signal to the optical fiber 10G, it is possible to prevent the data signal received at the optical converter 3b from being returned to the Leopard converter 110 side via the single electrical connection 34. can.

Since the optical transmission system according to the present invention is configured as described above, signal transmission between the main station device and the remote terminal device is performed by light, and therefore, it is hardly affected by external noise. Moreover, since the connection with the main station device uses a stack configuration in which optical fiber cables and photoelectric converter modules are cascaded in correspondence with the terminal devices, the signal input from the main station device 1 is dependent on the number of terminals. independent, 1
The number of terminals may be 2 to 2. Therefore, not only can the system be constructed at a low cost when initially installing a system with only a small number of connected terminals, but also the system is highly expandable since the subsequent addition of terminals can be done simply by connecting modules. Furthermore, the photoelectric converter on the main station side is supplied with power only from the main station device, and as long as the main station device is powered on, the transmission path to the photoelectric converter on each terminal side is in a communicable state. Therefore, the operating state of the total system is not affected by the power-on state of the terminal device, and the reliability of the system is high.

Note that this system can also be connected to conventional transmission lines using electric signal lines such as coaxial cables, making it compatible with existing systems. For example, some terminal equipment is connected to the main station equipment via a connection module using an optical fiber transmission line as described above, while other terminal equipment is connected to a similar connection module using a coaxial cable transmission line instead of the optical transmission line. It is also possible to configure a system in which an optical fiber transmission line and a coaxial cable transmission line are combined so that the connection module is connected to the main station apparatus.

[Brief explanation of drawings]

FIG. 1 is a block diagram for explaining the basic concept of the optical transmission system according to the present invention, FIGS. 2 to 4 are block diagrams showing embodiments of the optical transmission system according to the present invention, and FIG. FIG. 3 is a functional diagram showing an example of a transmission direction switching circuit applied to a modification of the embodiment. Explanation of symbols of main parts 1... Main station device, 2... Terminal device, 3... Optical fiber transmission line, 3a, 3b... Photoelectric converter, 30.34
...Electrical connection, 32.36...Power supply connection, 100
゜102... Optical fiber, 104,110... Electrical/optical converter, 106,108... Optical/electrical converter. Patent applicant Ricoh Co., Ltd. Figure 1 Figure 2 Figure 5 Figure 10

Claims (1)

[Scope of Claims] An optical fiber transmission line, which is connected to one end of the optical fiber transmission line, converts an electrical signal into an optical signal and transmits it to the optical fiber transmission line, and transmits the optical signal from the optical fiber transmission line. a first photoelectric converter that converts a received optical signal into an electrical signal; and a first photoelectric converter that is connected between the other end of the optical fiber transmission line and a slave device and converts the electrical signal from the slave device into an optical signal. a second photoelectric converter that converts the optical signal received from the optical fiber transmission line into an electrical signal and sends it to the slave device, the first photoelectric converter mutual communication between the master station apparatus and the slave station apparatus by commonly connecting the apparatus to the master station apparatus and transferring electrical signals between the master station apparatus and the first photoelectric converter. . An optical transmission system, wherein the first photoelectric converter receives power from the master station device, and the second photoelectric converter receives power from the corresponding slave station device.