JPS58111447A - Bidirectional optical data bus - Google Patents

Abstract

PURPOSE:To attain the constitution of fail-soft against a disconnection of transmission line, by providing two transmission lines in parallel for optical signals and a beam splitter at every communication station, and connecting the splitter to a transmitter and a receiver. CONSTITUTION:Each communication station 3i(i=1-n) connected to parallel optical transmission lines 1, 2 is provided with optical beam splitters SP4i1, 4i2 and the SP4i1 is connected to a receiver 3i1 and the SP4i2 is connected to a transmitter 4i2. The transmission lines transmit signals to opposite directions with each other, an optical signal incoming from the right of the line 1 is transmitted to down-stream via a lateral optical path in the SP4i1 and branched into a longitudinal optical path and inputted to the receiver 3i1. The optical signal from left to right in the transmssion line 2 is transmitted to the down-stream via a lateral optical path in the SP4i2, branched at the SP4i1 through a longitudinal optical path and transmitted to the receiver 3i1 and the down-stream of the transmission line 1. A transmission signal from the transmitter 3i2 is branched into the longitudinal and lateral optical path in the SP4i2 and transmitted to the receiver 3i1 and the lateral optical path in the SP4i1.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is an improvement to a bidirectional multidrop optical data bus. More specifically, the present invention relates to reducing loss and increasing reliability of a bidirectional multi-drop optical data bus.

A multi-drop optical data bus has the advantage that all communication will not be interrupted even if any of the communication stations connected to it stop functioning. Furthermore, making this type of optical data bus bidirectional has the advantage that the optical transmission line does not need to be looped.

Conventional bidirectional multi-drop optical data buses use one optical transmission line and connect each communication station through two optical couplers in opposite directions. Two optical transmission lines are used, and one end of the transmission lines is connected through a regenerative amplifier, and one transmission line has the transmitter of each communication station directed toward the regenerative amplifier through a unidirectional optical coupler. The other transmission line connects the receivers of each communication station to the regenerative amplifier through a one-way optical coupler.

With a single transmission line, signals can be transmitted bidirectionally on the transmission line, so even if the transmission line breaks midway,
On both sides of the disconnection point, communication can be performed between a plurality of communication stations connected to each transmission line. Therefore, it is a fail soft against disconnection of the transmission line. Although this has the advantage of higher reliability, since two optical couplers are used per communication station, there is a disadvantage that the optical signal is attenuated significantly due to the insertion loss of the optical coupler.

For systems with two transmission lines, one transmission line is for the outbound path and the other is for the return path, and the optical signal is transmitted in only one direction, so if either transmission line is disconnected, all communication will stop. There are drawbacks. In particular, since active elements such as regenerative amplifiers are connected in series to the transmission line, there is a risk that a failure in this part will stop all communications. Also, in this type of communication, there is an optical coupler for each communication station on both the outbound and return routes, so the attenuation of the optical signal due to the insertion loss of the optical coupler is large.

SUMMARY OF THE INVENTION An object of the present invention is to provide a bidirectional multidrop data bus that is fail-proof against transmission line disconnections and has low optical coupler insertion loss.

In order to achieve this object, the present invention provides two optical signal transmission lines in parallel, and each of these image transmission lines is provided with a beam splitter for each communication station. The receivers of each communication station are connected to the receivers of each communication station, and the transmitters of each communication station are connected to the beam splitter of the other transmission line. It is designed to transmit optical signals between objects.

Hereinafter, the present invention will be explained in detail with reference to the drawings.

FIG. 1 is a conceptual block diagram of an embodiment of the present invention.

In FIG. 1, 1 and 2 are optical signal transmission lines laid in parallel, 3l-3n are communication stations, and 311
-3nl are receivers for communication stages 3 and 31-3++, and 312-3n2 are receivers for communication stations 3l and 312-3n2, respectively.
-3n transmitters, 411-4n1 and 412-4n2
is an optical beam splitter provided for each communication station 3l-3n.

Beam splitter 4ij (i-1...n, J-1o
r2) has the function of splitting the lights in two optical paths and inserting them into each other's optical paths, for example, as shown in FIG. This can be achieved by irradiating the two beams, dividing both into transmitted light and reflected light, and mixing each other's reflected light into each other's transmitted light. Of course, the configuration of the beam splitter is not limited to this.

In the beam splitters 4i1 and 4i2 belonging to the same communication station 31, one optical path (tentatively called a vertical optical path) is connected in series, and the other optical path (tentatively called a horizontal optical path) is connected to the transmission line 1 and the beam splitter 4i2, respectively. 2 in series. A receiver 311 is connected to one end of the longitudinal optical path of the beam splitter 4i1, and a transmitter 312 is connected to one end of the beam splitter 4i2. The optical signal output from the transmitter 312 is input to the receiver 3i1 through the vertical optical path, and is also input to the receiver 3i1 through the beam splitters 411 and 412.
The signals are branched and sent out to transmission lines 1 and 2, respectively. The signal transmission directions of transmission lines 1 and 2 are opposite to each other.

An optical signal arriving from the right side of the transmission line 1 is transmitted downstream through the horizontal optical path at the beam splitter 4i1, and is split into a vertical optical path and input to the receiver 3i1. The optical signal arriving from the left side of transmission line 2 is a beam
At the splitter 4:2, it is transmitted downstream via its transverse optical path and split into a longitudinal optical path to reach the beam splitter 4i1, where the input signal to the receiver 3i1 and downstream of the transmission line 1 are transmitted. divided into transmission signals.

With such a configuration, the transmission output of the transmitter 3i2 is split by the beam splitter 4i2 and transmitted to the right on the transmission line 2, and is also transmitted through the beam splitter 4i2, branched at 4i1, and transmitted to the transmission line. 1 is transmitted to the left. That is, the transmission output of the station 31 is simultaneously sent to the right and left sides, resulting in bidirectional transmission. In addition, the input signal to the receiver 3:1 is split into the beam splitter 4i1 from the right side of the transmission line 1, and inputted from the left side of the transmission line 112 at the beam splitter 4i1.
There are two types of input: one that branches at i2 and inputs through 4i1, and the other that inputs in both directions. That is, input can be received from either the right or the left, and bidirectional input signals can be received.

In this way, a bidirectional optical data bus can be realized. When communicating between two communication stations on this optical data bus, the number of optical couplers intervening on the way is equal to the number of intervening communication stations. This is half of the conventional case, and the loss is reduced accordingly.

Further, since neither of the transmission lines 1.2 includes any active elements, reliability is high.

Now, transmission line 1 or 2 is connected to communication stages 31 and 3.
If there is a disconnection at (1+l), communication □ will be interrupted on the right and left sides of the disconnection point, but in the right system and left system, two-way communication will be interrupted in the same way as above. Sexual communication continues. In other words, it is fail software.

[Brief explanation of the drawing]

FIG. 1 is a conceptual configuration diagram of an embodiment of the present invention, and FIG. 2 is a
FIG. 2 is a configuration diagram of a specific example of a portion of FIG. 1; 1.2...Optical transmission line, 3l-3n...Communication stage. 311-3nl...Receiver, 312-3n2...Transmitter, 411-4n1.412-4n2-...Beam.
Zubritta, 40--half mirror.

Claims (1)

[Claims] An e-mail splitter that has two optical transmission lines laid in parallel and two optical paths, and splits the light from each of these optical paths and inserts the light into the other's optical path, and is used for each receiver at each communication station. a first beam splitter provided in the transmission line, with one optical path connected in series in alignment with one of the two transmission lines and the other optical path connected to the receiver of the communication station, and a similar beam splitter; a beam splitter, which is provided for each transmitter of each communication station and has one optical path connected in series with the other side of the transmission line aligned in the opposite direction to the first beam splitter; a bidirectional optical data beam with a second beam splitter connected to the transmitter of the communication station and connected in series with the other optical path of the first beam splitter;
bus.