JPH0287740A - signal transmission system - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a signal transmission system that interconnects a plurality of terminal stations and transmits signals.

[Prior Art] Currently, signal transmission systems that mutually transmit signals over local area networks are becoming widespread. Topologies of signal transmission systems include star, bus, and loop types, among which the loop type is widely used because it has various advantages. As shown in FIG. 6, the loop type is one in which a plurality of terminals (stations) 50 are connected with optical fibers 51 to form a ring-shaped signal transmission path. The advantage of this loop type is that the transmission at each terminal station is between two points, so the load on the transmitting/receiving module is light.
It can be simple, and it is easy to take measures against failures (recovery in case of wire breakage, terminal failure, etc.).

[Problem to be Solved by the Invention] However, in a loop-type signal transmission system, it is necessary to create a closed ring of transmission lines, so it is necessary to configure this loop in advance when installing a station. This has to be taken into consideration, and there is a problem that there is little freedom in arrangement. This problem becomes a particular problem when expanding the network and constructing more complex signal transmission paths within a limited space such as an intelligent building.For example, as shown in Figure 7, multiple stations 50a
~50f are arranged sequentially according to needs, and adjacent stations are connected with optical fibers 51a. In order to form a closed loop, it is necessary to use a feedback cable to return the signal from the terminal station 50f to the starting station 50a. The optical fiber 51b must be provided, therefore, not only the needs of the station equipment but also
A signal path for returning a signal must always be taken into account, and for this reason, although loop-type signal transmission systems are functionally superior, they have the drawback of being restricted in terms of placement.

[Means for solving the problem] In the signal transmission system of the present invention, at least two
They are connected by two signal transmission lines, one of which is used as a feedback line to route the signal in a loop.

゛[Operation] By connecting signal transmission paths between each station to route signals in a loop, stations can be arranged as needed.
Along with this, a C loop is automatically configured, and its functionality is equivalent to the advantages of the loop type described above.
As for the topology, it is possible to provide a signal transmission system with a high degree of freedom in which the signals are connected in a line like a bus type and there is no need to consider an annular arrangement.

[Example] Next, an example of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic diagram showing the configuration of a first embodiment of the present invention.

la, lb, lc are terminals, 2a,
2b and 2c are terminal stations 1a, respectively.

This is a transmitter for lb and 1c. 3a, 3b, and 3c are transmitting units 2a of the terminal stations 1a, lb, and lc, respectively.

2b and 2c.

4a, 4b, and 4c are terminal stations 1a and lb, respectively.

This is the receiving section of the lc. 5a and 5b are repeat stations (terminals), and 6a and 6b are repeat stations 5a and 6b, respectively.
5b is the transmitter. 7a.

7b, 7c, and 7d are repeat station 5a and terminal station 1c, respectively.
, lb, and la. 8a, 8
b and 8c are terminal stations 1c, respectively.

These are optical fibers placed inside 1b and 1a.

9a and 9b are receiving units of repeat stations 5a and 5b, respectively. Reference numeral 10 denotes an optical fiber connecting the transmitter 6b of the repeat station 5b and the receiver 4a of the terminal station 1a.

As is clear from FIG. 1, the optical fibers 3a, 3b, 3c, and 10 connect the transmitter and receiver of adjacent terminal stations la, lb, and lc or repeat stations 5a and 5b. The tip fibers 7a, . . . , 7d are connected in order from the transmitting section 6a of the repeat station 5a to the adjacent terminal stations 1c, .
lb and la are connected to reach the receiving section 9b of the repeat station 5b. Optical fiber 7a,...
7d is an optical fiber 8a within the terminal stations 1c, lb, and la.

It is connected to 8b and 8c.

The optical signal transmitted from the transmitting section 2a of the terminal station 1a is transmitted through the optical fiber 3a and is received by the receiving section 4b of the terminal station 1b, whereby the signal is transmitted from the terminal station 1a to the terminal station 1b. It will be done. Similarly, the terminal station lb transmits a signal from the transmitter 2b, and the signal is transmitted through the optical fiber 3b and sent to the adjacent terminal station. In this way, the terminal station 1c receives the transmitted signal at the receiving section 4c, and then the leftmost terminal station 1a receives the transmitted signal.
The next terminal station 1c, which has completed the signal transmission from the terminal station 1c to the rightmost terminal station 1c, first sends a signal to the repeat station 5a in order to return the signal to the terminal station 1a. That is, the terminal station 1c transmits a signal from the transmitter 2c, and the signal is transmitted to the optical fiber 3.
c and is sent to the receiving section 9a of the repeat station 5a.

The repeat station 5a sends the received signal as it is or after shaping and amplifying the signal into the optical fiber 7a from the transmitter 6a. This signal is transmitted through the optical fiber 8a in the terminal station 1c.
are propagated as they are through the optical fiber 7b.

8b, 7c, 8c, 7d, repeat station 5b
is received by the receiving section 9b. The repeat station 5b sends the received signal as it is or after performing waveform shaping, amplification, etc., into the optical fiber 10 from the transmitter 6b. Since this signal is received by the receiving section 4a of the terminal station 1a, the transmission of the signal around each station is now complete.

Figure 2 is a schematic diagram showing the configuration of a second embodiment of the present invention.

11a, llb, llc are terminal stations, 12a, 12b
, 12c are terminal stations 11a, respectively.

a 13 a which is the first transmitter of 11b and 11c.

13b and 13c are terminal stations 11a and llb, respectively.

11c is an optical fiber connected to the first transmitting sections 12a, 12b, and 12c. 14a, 14b.

14c are the terminal stations 11a, 1. ]b, the first receiving section of the llc. 15a and 15b are repeat stations (terminals), and 16a and 16b are transmitting and receiving units of the repeat stations 15a and 15b, respectively.

FIG. 3 is a diagram showing the detailed configuration of the transmitting/receiving sections 15a and 15b.

41 is a light emitting element, such as a semiconductor laser or an LED. 42a, 42b, and 42c are focusing lenses. 43 is a beam splitter, and 44 is an optical fiber. 45 is a light receiving element, such as a p-1-n photodiode or an avalanche photodiode.

In FIG. 2, 17a, .'', 17d are optical fibers connected to repeat stations 15a, 15b, respectively. 18a, 18b, 18c are optical fibers connected to end station 1, respectively.
These are optical fibers placed inside 1c, llb, and lla. 19a, 19b and 20a, 20b are repeat stations 15a, respectively.

15b and a receiving section. 21 is an optical fiber that connects the transmitter 19b of the repeat station 15b and the receiver 14a of the terminal station 11a.

32a, 32b, 32c are terminal stations 11a, ll, respectively.
b, the second transmitter of the llc.

33a, 33b and 33c are terminal stations 11a, respectively.

34a is an optical fiber connected to the transmitting units 32a, 32b, and 32c of 11b and 11c.

34b and 34c are terminal stations 11a, respectively.

11b, llc's second receiving section. 40 is the transmitter 19a of the repeat station 15a and the second receiver 3 of the terminal station 11c.
4c.

The optical fiber connections are as shown in FIG.
The transmitting section and the receiving section of adjacent stations among the repeat stations 15a and 15b are connected, and the same applies to the optical fibers 33a, 33b, 33c and 40. Further, the optical fibers 17a, . . . , 817d sequentially connect adjacent terminal stations lc, lb, la from the transmitting/receiving section 16a of the repeat station 15a, and reach the transmitting/receiving section 16b of the repeat station 15b.

A feature of this second embodiment is that two loops are functionally formed. The first loop is indicated by a solid arrow and is almost the same as the loop described in the first embodiment. That is, the first terminal station 11a
Suppose that a signal is sent to the optical fiber 13a from the transmitter 12a of the terminal station 11b and the transmitter 12 of the ILc.
b, 12c and receiving sections 14b, 14c, optical fiber 1
3b and 13c, and is transmitted to repeat station 15.
It is received by the receiving unit 20a of a. Of course, during this transmission, the signal may be updated to a new one by the terminal stations 11b, 11c, etc. Repeat station 15a
The signal received by the receiving section 20a is sent out from the transmitting/receiving section 16a to the optical fiber 17a, either as is or after being waveform-shaped and amplified.

Since the transmitter/receiver has the configuration shown in FIG. 3, it can transmit to and receive from an optical fiber. That is, the light emitting element 41 emits light according to the drive signal.
, the light beam is collimated by the converging lens 42a. This parallel light beam is partially reflected by the beam splitter 43, condensed by the converging lens 42b, and guided to the optical fiber 44. As a result, signals are sent to the optical fiber 44. Conversely, when receiving a signal sent from the optical fiber 44, the light beam emitted from the optical fiber 44 is transmitted through the focusing lens 4.
2b, a portion of the light passes through the beam splitter 43, is focused by the focusing lens 42b, and is detected by the light receiving element 45.

The signals sent to optical fiber 17a according to FIG. 2 are transmitted to optical fibers 18a, 17b, 18b.

Repeat station 15 passes through 17c, 18c, and 17d.
b is received by the transmitting/receiving section 16b. The received signal is suitably processed and sent from the transmitter 19b to the first receiver 14a of the terminal station 11a via the optical fiber 21, completing the first loop.

On the other hand, the second loop is indicated by a dotted arrow, and although it is in the opposite direction to the first loop, the method of transmitting the signal in a loop is exactly the same as the first loop. Terminal 1
If you simply follow the flow of the signal sent out from the second transmitting section 32a of 1a, the optical fiber 33a, the receiving section 20b of the repeat station 15b, the transmitting/receiving section 16b, and the optical fiber 17d.

18c, 17c, 18b, 17b, 18a.

17a, and reaches the transmitting/receiving section 16a of the repeat station 15a. Next, the signal is transmitted from the transmitting section 19a of the repeat station 15a to the optical fiber 40, and is transmitted to the terminal station 11b.
, LLC's second transmitting sections 32b, 32c and second receiving section 34b.

34c or optical fibers 33b and 33c, and is received by the receiving section 34a of the terminal station 11a. It is clear that a second loop is now formed.

In the second embodiment, since a double loop is formed, transmission is not inhibited even if an optical fiber breaks or a failure occurs in the transmitter or receiver.

In this second embodiment, a third group of optical fibers is used. That is, the first group of optical fibers is optical fiber 21.
13a, 13b, and 13c.

The second group of optical fibers are 17a, . . . , 17d and 1
8a, ..., 18c, and the third group of optical fibers is 3
3a, . . . , 33c, 40. As explained above, the first loop is formed by the first and second groups of optical fibers, and the second loop is formed by the second and third groups of optical fibers. If any of the optical fibers in the first group, for example 13a, breaks, there will be no problem if the signal is transmitted using the second loop. Also, a third group of optical fibers, for example 13b
When the first loop is broken, the signal can be transmitted using the first loop.

FIG. 4 is a schematic diagram showing a signal transmission method when the second group of optical fibers is broken.

61 is a broken optical fiber. The broken optical fiber 61 is the optical fiber that connected the terminal station 11a and llb.
It is assumed that 17c in FIG. 2 is broken. When the second group of optical fibers breaks, as shown in FIG. 4, a new loop is formed between the first and third group of optical fibers and signal transmission is performed in the direction of the arrow. At both ends of the optical fiber being used, there is a terminal station 1 in the direction of the arrow! a, llb, llc and repeat station 1
It is clear that such a loop can be formed since there are transmitting sections and receiving sections 5a and 15b. Such a loop can be formed even if all terminal stations and repeat stations are not connected or by looping back in the middle.
For example, in addition to the broken optical fiber 61, the optical fiber 33
b.

If 13a is also broken, the terminal station to the right of terminal station 11b,
A loop can be formed using only repeat stations. That is, the terminal station 1.1b transmits the signal received by the second receiving section 34b into the destination fiber 13b from the first transmitting section 12b instead of the second transmitting section 32b. We have explained the case where an optical fiber breaks as a failure, but in the case of a failure in the transmitter, receiver, or transmitter/receiver, it also depends on which group of optical fibers the failed part is related to, and whether the optical fibers in that group are broken. All you have to do is consider forming a loop using the same fault countermeasures mentioned above.

In the above description of the embodiments, it is assumed that the transmission signal is light, but the present invention can also be applied to the case of transmitting electrical signals. In this case, coaxial cable instead of optical fiber,
Using twisted pair wires, the transmitting section and receiving section transmit optical signals,
It is sufficient to transmit and receive electrical signals instead of receiving them.

In the explanation of the embodiment, the repeat station is placed on both sides of the connected terminal stations, but the repeat station function may be provided to the terminal station at the end of the connection. If you add a repeat function to amplify the signal from the terminal, you can increase the number of terminal stations that can be connected. When repeating, in addition to amplification, waveform shaping or the like may be performed before playback.

Figure 5 is a schematic diagram showing the configuration of a third embodiment of the present invention.

In this embodiment, the plurality of terminal stations 50a to 50f are arranged not in a line but in a form having a bent portion. As in the previous embodiment, two optical fibers 51a,
53 (53 is a return fiber).

When compared with the conventional example shown in FIG. 7, it can be seen that the feedback optical fiber 51b for loop formation is not required, and the degree of freedom of the station equipment, that is, the degree of freedom of network configuration is improved.

[Effects of the Invention] As explained above, the present invention has a configuration in which a signal line for returning signals to form a loop is provided while connecting terminal stations in advance, so that the function of the present invention is to perform loop-shaped signal transmission. It is equivalent to the system, the transmitting and receiving modules are simple, and troubleshooting is easy, but the topology is not limited to forming it in a loop shape, allowing the system to be expanded to any shape, and signal transmission similar to a bus type. It has the effect of providing a system.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing the configuration of the first embodiment of the present invention, FIG. 2 is a schematic diagram showing the configuration of the second embodiment of the present invention,
FIG. 3 is a diagram showing the detailed configuration of the transmitter/receiver section, FIG. 4 is a schematic diagram showing the signal transmission method when the optical fiber is broken, and FIG. 5 is a diagram showing the configuration of the third embodiment of the present invention. A schematic diagram, FIG. 6 is a diagram for explaining the form of a loop type LAN, and FIG. 7 is a diagram for explaining problems in a conventional example of a loop type LAN. 1 a, 1 b, l c... terminal station, 2 a, 2
b, 2cm transmitter, 4a, 4b, 4c/"receiver, 5a, 5b... repeat station, 6a, 6b... transmitter, 9a, 9b... receiver, 11a, l lb, 11cm end stations, 12a, 12b, 12cm first transmitter, 14a, 14
b, 14c...first receiving section, 15a, 15b--repeat station, 16a, 16b--transmitting/receiving section, 19a, 19b--transmitting section, 20a, 20b''--receiving section, 32a, 32b, 32cm second transmitting section, 34a, 34;
b, 34cm second receiving section, 41... light emitting element, 42a, 42b, 42cm focusing lens, 43... beam splitter, 45... light receiving element, 61... broken optical fiber.

Claims (1)

[Claims] 1. A signal transmission system configured such that adjacent terminals among a plurality of terminals are connected by at least two signal transmission paths, wherein one of the at least two signal transmission paths The signal transmission directions of one signal transmission path and the other signal transmission path are opposite to each other, and using this one signal transmission path, one terminal is the starting end and the other is the terminal terminal. Sequentially transmit signals, then
A signal transmission system capable of configuring a closed loop in which a signal goes around by transmitting a signal from the termination terminal to the start terminal using another signal transmission path. 2. The signal transmission system according to claim 1, wherein the plurality of terminals are arranged in a straight line.