JPH04199104A - Optical communication path and its laying method - Google Patents

Abstract

PURPOSE:To reduce the quantity of construction work at the time of laying an optical fiber cable by forming an extra part for branching and connecting on the optical fiber cable inside a manhole. CONSTITUTION:The end of a drain pipe 13 is connected with a privately provided sump 91 provided on a house 2, and a publicly provided measure 92 as a sump is provided on the middle of the drain pipe 13. The waste water of the housing 2 passes the drain pipe 13 from a measure 91 via the measure 92, and flows into a branch pipe 12. The optical fiber cable is installed from a sewage-treatment plant to the inside of a main pipe 11, and the optical fiber cable on a trunk line 6, is branched inside plural main pipe manholes for checking (unshown in the figure) provided in the path of the main pipe 11, and installed inside the branch pipe 12, as a branch line 7. The optical fiber cables which are pulled into respective houses 2, 2... are connected optical modems (unshown in the figure) which convert an optical communication signal into an electrical signal, or the electrical signal into the optical communication signal, and the converted signal is given to a POS terminal.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an optical communication path using an optical fiber cable as a transmission medium and a method for laying the same.

[Prior art]

In recent years, information communication networks using optical fibers as transmission media have been constructed in various places. Most of them are
It is a dedicated line that connects each large-scale communication terminal in a small number of large-scale business offices, etc., and between a large-scale communication terminal and an information communication base equipped with a large computer. Telephone lines are used for communication between small-scale communication terminals and between small-scale communication terminals and information communication bases equipped with large computers. There are the following reasons why telephone lines are used for communication regarding each small-scale communication terminal. That is, since telephones have a high penetration rate, telephone lines are installed in most of the houses where the small-scale communication terminals are to be installed, and they are easy to use.

On the other hand, when trying to use other transmission media, the following problems arise. That is, for example, when installing an optical fiber cable, it is necessary to construct a utility pole exclusively for the installation, and when burying the optical fiber cable underground, it is necessary to construct an underground conduit. This is because the cost required for these constructions is high.

In order to reduce such construction costs, one possible method is to install optical fiber cables in an existing communication route network, such as a sewerage piping network, in which communication routes to each house have been established. Small businesses and households that use information communication using optical fiber as a transmission medium are concentrated in urban areas, so it is necessary to install optical fiber cables using the sewerage piping network maintained in urban areas. Once installed, a route for optical fiber cables to each house can be secured.

A sewerage piping network consists of branch pipes, which are pipes that combine sewage from each house in a given area, and main pipes, which combine sewage from multiple branch pipes and flow to a sewage treatment plant. It is made up of.

When installing optical fiber cables in the sewer piping network configured in this manner, the optical fiber cables are extended from the main pipe to each of its branch pipes. The installation of fiber optic cables into individual houses is a process that involves installing many branch pipes in the sewerage network.

Optical fiber cable branches through manholes for inspection.

A possible method is to draw the optical fiber cable into the house from one of these manholes, which is the connection point, and is closest to the house where the optical fiber cable is to be drawn.

In this way, optical fiber cables are branched at manholes.
When installing a new fiber optic cable to the sewer pipe network, when connecting and bringing fiber optic cable into the house,
In order to facilitate the subsequent work to bring optical fiber cables into the homes of new subscribers to the optical communication network, the core wires of the optical fiber cables are branched at all manholes provided in the branch pipes. A possible construction method is to cut a predetermined number of connections in advance, and then attach the branch, the branch containing the connection part, and the connection box to the manhole cover.

[Problem to be solved by the invention]

However, since the manholes are normally provided every 30m to 50m along the route of the branch pipe, the above-mentioned construction method does not require cutting the core of the optical fiber cable every such short distance. However, there is a problem in that the amount of construction work increases and construction costs become expensive.

The present invention has been made in view of the above circumstances, and when installing optical fiber cables of an optical fiber network in which manholes are used as branching and connecting points of optical fiber cables to a sewerage piping network, branching and connection boxes in manholes are used. By providing an extra length in advance for branching and connecting the optical fiber cable in the interior, and branching and connecting the optical fiber cable at the extra length, the amount of work required when installing the optical fiber cable can be reduced. The purpose of the present invention is to provide an optical communication channel and its installation method that reduce construction costs.

[Means to solve the problem]

The optical communication path according to the present invention is provided in an underground network provided with a plurality of manholes, and branches at the manhole.
The optical communication path uses an optical fiber cable as a transmission medium to be connected, and is characterized in that the optical fiber cable inside the manhole is provided with an extra length for branching and connecting.

The method for laying an optical communication line according to the present invention is to lay an optical communication line using an optical fiber cable as a transmission medium, which is installed in an underground network provided with a plurality of manholes, and branched and connected at the manhole. This construction method is characterized in that an extra length is provided in advance in the optical fiber cable in the manhole, and the optical fiber cable is branched and connected at this extra length.

[Function] In the optical communication path of the present invention, the optical fiber cable in the manhole is provided with an extra length for branching and connecting, so this extra length can be cut to branch and connect the optical fiber cable. It can be carried out.

Further, in the optical communication path installation method of the present invention, the extra length is provided in advance, and then the optical fiber cable is branched,
In order to perform the connection, branching and connection of the optical fiber cable can be performed as necessary.

〔Example〕

The present invention will be specifically described below based on drawings showing embodiments thereof. FIG. 1 is a schematic block diagram showing the overall configuration of an optical communication path according to the present invention.

In the figure, 12.12... are branch pipes of the sewerage piping network, and the branch pipes 12, 12... have drainage pipes 13, 13... from the houses 2, 2..., respectively. The branch pipes 12, 12, . . . are provided with a large number of manholes 3 for inspection 2. In addition,
Here, the manhole 3 refers to a hole for inspection of work 1, which includes not only a hole through which a worker can enter, but also a small hole through which a worker cannot enter. Branch pipe 12,
12... are respectively connected to the main pipes 11, 11... of the sewerage piping network that extend over long distances, and the sewage flowing through the branch pipes 12, 12... is treated as sewage. The water flows into main pipes 11, 11, etc., which lead directly to field 1, respectively. The sewage flowing into the main pipes 11, 11... is collected in a sewage treatment plant 1 and subjected to sewage treatment. This sewage treatment plant 1 is equipped with a large computer and equipment for providing and managing optical communication information.

In this way, in the sewage pipe network, the routes from the sewage treatment plant 1 to the houses 2, 2, . . . and the routes between the houses 2, 2, . . . are connected by sewage pipes. Optical fiber cables, which are the transmission medium of the optical information communication device, are installed inside the main pipes 11, 11, . . . and branch pipes 12, 12, . . . of the sewerage piping network. For each house 2, 2..., the house 2
, 2 . . . The optical fiber cables are branched within the manholes 3, 3 . . . closest to the manholes 3, 3 .

FIG. 2 is a schematic perspective view showing the installation state of the optical fiber cable in the optical information communication device according to the present invention. Second
In the figure, reference numeral 91 denotes a private device that is a drainage basin provided in the house 2, and the end of the drain pipe 13 is connected to the private device 91. Further, a public basin 92 serving as a drainage basin is provided in the middle of the drain pipe 13. Drainage water from the house 2 flows from a private vessel 91 through a drain pipe 13 via a public tank 92, and then flows into a branch pipe 12. The optical fiber cable is installed in the main pipe 11 from the sewage treatment plant 1,
The optical fiber cable in the main line 6 is connected to the main manholes (main manholes) for maintenance 2 inspection provided in multiple places along the route of the main line 11.
(not shown), and the branched optical fiber cable is installed as a branch line 7 in the branch pipe I2.

When pulling optical fiber cables into each house 2, 2, etc., branch wires 7 are attached to the lower part of the manhole 3 cover, branch wires 7 are branched in the junction box 4, and the branched optical fiber cables are connected to the house wires. Branch pipe 12 as 8. Drain pipe 13. Public square 9
2 and private equipment 91 to the house 2. house 2,
The optical fiber cable drawn into 2... is connected to an optical modem (not shown) that converts an optical communication signal (or electrical signal) into an electrical signal (or optical communication signal). The optical modem is connected to an optical communication terminal, and the signal converted by the optical modem is given to the terminal. Further, the electrical signal given from the terminal to the optical modem is converted into an optical communication signal, branched via the house line 8, and given to the junction box 4.

The branch line 7 is a cable in which approximately 20 tape-shaped four-core optical fibers are stacked and housed in a grooved spacer and covered, and a tension member is inserted in the center of the cable. This gives the cable tensile strength. The trunk line 6 is a cable made by bundling and covering a plurality of such cables. Further, the house line 8 is a two-wire branch line formed by branching one of the four-core optical fiber core wires of the branch line 7.
The optical fiber core wire is led to the houses 2, 2, . . . and connected to a terminal, and from this terminal, the optical fiber core wire is again joined to the branch line 7. However, the four-core optical fiber is an optical fiber required for full-duplex communication, and a single optical fiber is sufficient for half-duplex communication.

Using optical fiber cables installed in this way, optical communication between the sewage treatment plant 1 and each house 2, 2... is possible, as well as optical communication between each house 2, 2... It becomes possible.

As described above, when the manhole 3 is used as a branching place for the branch line 7, a branching/junction box 4 for storing a part where the branch line 7 is branched and connected is arranged on the back side of the cover 31 of the manhole 3.

FIG. 3 is a longitudinal sectional view of the manhole 3. In this figure, a manhole 3 is a vertical hole with a circular cross section and a predetermined depth formed underground, its wall surface is hardened with concrete, and its lower end communicates with a branch pipe 12. Further, an annular support frame 32 is formed at the upper end of the manhole 3 and has a protrusion 320 of a predetermined height provided around the inner peripheral surface thereof. A cast iron disc-shaped lid 31 having approximately the same diameter as the inner periphery of the support frame 32 has an edge that is connected to the protrusion 320.
It is supported by the support frame 32 in an upwardly abutting manner and closes the opening of the manhole 3. Further, on the back side of the cover 31 of the manhole 3, a branching/junction box 4 for storing a portion where the branch line 7 is branched is arranged.

For branching to the back side of the cover 31 of the manhole 3 and installing the junction box 4, branch to the cover 31, which is an existing standard iron cover.

When installing the junction box 4, thread the lid 31,
This is done by attaching a mounting fitting (not shown) for the branch and junction box 4 which has been subjected to corrosion protection to the lid 31 by screwing a bolt, and fixing the branch and junction box 4 to this fitting. When a new manhole 3 is to be installed, a cover 31 with the above-mentioned mounting fittings provided on the back side of the manhole 3 is prepared in advance, and the branch and junction boxes 4 are attached to the mounting fittings of this cover 31. Note that when a new manhole 3 is installed, a cover 31 having an integrally formed mounting part corresponding to the above-mentioned mounting fittings may be created on the back surface of the manhole 3, and the branch and connection box 4 may be attached to this mounting part. When branching optical fiber cables in the manhole 3 with the branching and junction box 4 attached to the back side of the lid 31 in this way, the operator must take out the lid 31 and turn it over as shown by the broken line in the figure. Place the optical fiber cable on the ground, open the branching and junction box 4, and branch the optical fiber cable.

Inside the manhole 3, there is high humidity and a large amount of filth, so gas is generated due to the decomposition of the filth and there is a lack of oxygen.The bottom of the manhole 3 is branched, and the optical fiber cable is connected to the junction box It is not in a state where branching work can be performed.

In addition, in the manhole 3, either open the cover 31 and perform various operations such as cleaning the inside of the manhole 3, or open the branch and junction box 4 so that the hole can enter the manhole 3 without damaging the branch and junction box 4.
must be installed. Therefore, when installing the branching and connecting box 4 inside the man ball 3, it is installed on the back side of the lid 31 as shown in FIG. Lid 3 like this
If the branching and junction box 4 is attached to the back side of the optical fiber cable 1, branching work of the optical fiber cable can be easily performed. This is because if the branch/junction box 4 is attached to the back surface of the cover 31, when the cover 31 of the manhole 3 is opened, the back surface of the cover 31 will be exposed above ground. For this reason, branching, junction box 4 is connected to lid 3.
It is attached to the back side of 1.

Next, the attachment position of the branch and the junction box 4 to the lid 31 will be explained. FIG. 4 is a schematic side view showing how the branch and junction box 4 are attached to the lid 31, and FIG. 5 is a schematic plan view showing how the branch and junction box 4 are attached to the lid 31.

The planar shape of the branch/junction box 4 is such that both corners of one long side of a rectangle are cut out, and the central part of the other long side is cut out by an appropriate width. This branch.

A branch wire 7 is connected to the junction box 4 from the notch on the other long side.
The house wire 8 is inserted from a portion other than the cutout portion on the other long side. When the branch line 7 and the house line 8 are inserted into the junction box attached to the back side of the cover 31 of the manhole 3, the optical fiber cables used for the branch line 7 and the house line 8 are inserted into the manhole as shown in FIG. The wire is laid along the wall of the manhole 3 from the bottom of the manhole 3 to the vicinity of the lid 31, and is bent near the boundary between the wall and the lid 31 to branch and enter the junction box 4. Generally, the bending radius of a cable is determined by the outer diameter of the cable, and the bending radius for fixed wiring is 10 times the outer diameter of the cable, and the bending radius for moving wiring is 20 times the outer diameter of the cable. . For this reason,
For example, when considering an optical fiber cable with a diameter of 30 mm to be used for branch line 7, its allowable bending radius is 300 m.
m or more. In addition, - branch pipe 12 of the sewerage piping network for boat fishing.
．． The diameter of the lid 31 used for the manhole 3 of 12... is 600 mm.

As a result, the width of the junction box 4 and the branch where the branch line 7 enters becomes approximately equal to the radius of the lid 31. For this reason, the branch/junction box 4 is placed unevenly on one side of the lid 31 as shown in FIG. must be installed. On the other hand, since the diameter of the house wire 8 is smaller than that of the branch wire 7 and the permissible bending radius is smaller, it is a branch where the house wire 8 enters.

The box width of the junction box 40 can be made wider than the box width of the part where the branch line 7 enters.

Next, the branching and wiring method inside the junction box 4, which is a feature of the present invention, will be explained. FIGS. 6(a) and 6(b) show branching and connection states of optical fiber cables.

FIG. 6(a) is a cross-sectional view of the junction box 4, and FIG. 6(a) shows the state where the branch line 7 is not branched into the house line 8, and FIG. 6(a) shows the state where the branch line 7 is branched into the house line 8. It shows.

First, the internal structure of the branch and junction box 4 will be explained. On the side of the branch and junction box 4 are cylindrical cable clamps 41a, 41a for fixing the optical fiber cables of the branch lines 7, 7.
The branch wires 7, 7 are branched from the holes of the cable clamps 41a, 41a, and enter the junction box 4. Branch wires 7, 7 that have entered the junction box 4 are stripped of their sheathing. Tension member 70
．． 70 is a branch, a cable clamp 41a in the junction box,
41a is cut leaving a predetermined length from each end, and the remaining cut ends are fixed with fixing members 44a, 4.
Branched by 4a.

It is fixed to the junction box 4. In this way, the branch wires 7, 7 are connected to the cable clamps 41a, 41a and the fixing members 44a, 44.
a and is branched and securely fixed to the junction box 4. Further, a connecting portion 43 for accommodating a connecting portion of an optical fiber cable is provided near the cut end of the tension member 70.70.

When installing a new branch line 7 in the branch pipe 12, 12, etc., as shown in Fig. 6(a), in the junction box 4, a small The branch wire 7 obtained by removing the covering by a length determined as above and cutting the tension member 70 is bent into a substantially figure-eight shape to form an extra length portion 7a.

After the branch line 7 is laid as described above, the branch lines 7, 7 are branched.

When making a connection, as shown in FIG. 6(b), the house wire 8 is placed on both sides of the cable clamps 41a, 41a at the side where the cable clamps 41a, 41a are provided.
Cylindrical cable clamps 41b, 41b・
. . . are provided, and the house wires 8, 8 . . . are cable clamps 41b.

The wire branches from the hole 41b and enters into the junction box 4. Branch, house line 8 entered into junction box 4,
8... has its covering removed, and the tension member 80
．． 80...branches, cable clamp 4H in the junction box
+, 4.1b is cut leaving a predetermined length, and the end of the remaining cut portion is fixed to the fixing member 44b.

44b... are respectively branched and fixed to the junction box 4.

In this way, the house wires 8, 8... are connected to the cable clamp 41.
b.

41b and the fixing members 44b, 44b, . . . branch and are reliably fixed to the junction box 4.

When branching the branch wire 7 into the house wires 8, 8, etc. in the branching and junction box 4 configured in this way, the branches entering from the cable clamps 41a, 41a as shown in FIG. 6(b). Optical fiber core wires 71, 71 of the extra length portion 7a of the wire 7...
Cut as many branches as needed. Then, the cut optical fiber core wires 71, 71... and the cable clamp 41
b, the optical fiber core wires 81, 81, . . . of the house wires 8, 8, .

In this way, the branch line 7 branches to the house line 8.

In the present invention as explained above, when installing a new branch line 7, a branch/junction box 4 is attached in advance to each manhole 3, 8..., and within the branch/junction box 4, the branch line 7 is installed. An extra length portion 7a is provided by removing the covering. When branching the branch line 7 into the house line 8 after laying the branch line 7, the optical fiber core wires 71, 71, etc. of the extra length part 7a of the extra length part 7a are cut by the necessary number of branches. By connecting this and the house line 8, the branch line 7 is branched. Therefore, in the installation work of the branch line 7, only the extra length 7a is provided in the branch and junction box 4, and no additional work is required for branching, and the branching to the house line 8 is not necessary. Branching and connection work can be carried out as required.

In addition, in this embodiment, whether equipment for providing optical communication information and managing the information is provided at the sewage treatment plant 1 or an information communication base having the said equipment is installed at a location other than the sewage treatment plant 1 is not limited to this. A drainage pipe 13 that is installed and exists in the information and communication base
A trunk line 6 may be installed inside the main pipe 11 via a branch pipe 12, and an optical communication network centered on this trunk line 6 may be installed. Furthermore, in this embodiment, the optical fiber cable is installed in the sewer network, but the invention is not limited to this, and if it is an underground communication route network that is equipped with a plurality of manholes 3 at predetermined intervals, the underground cable can be installed in the sewer network. The optical fiber cable may be installed in communication route networks such as underground piping and underground piping.

〔effect〕

The present invention is as described above, and when installing an optical communication path using a manhole as a branching and connecting point of an optical fiber cable,
Extra length is provided in advance for branching and connecting optical fiber cables in manholes, so branching and connecting work can be done as needed, reducing construction work when installing optical fiber cables for optical communication paths. The present invention has excellent effects such as reducing the amount and construction cost.

[Brief explanation of the drawing]

FIG. 1 is a schematic block diagram showing the overall configuration of the optical communication path according to the present invention, FIG. 2 is a schematic perspective view showing the installation state of the optical fiber cable, and FIG. 3 is a longitudinal cross-sectional view of a manhole. Figure 4 is a schematic side view showing how the branch and junction box are attached to the lid, Figure 5 is a schematic plan view showing how the branch and junction box are attached to the lid, and Figure 6 is a schematic side view of the optical fiber cable. branch,
It is a cross-sectional view of a branch and a junction box showing a connection state. 3... Manhole 4... Branch, connection box 6...
Main line 7... Branch line 8... House line 7a...
Excess length patent Applicant: Tokyo Sewerage Service Co., Ltd. Two other agents: Patent attorney Noboru Kono
4 Figure 5 Figure 6

Claims (1)

[Scope of Claims] 1. An optical communication path using an optical fiber cable as a transmission medium, which is installed in an underground network provided with a plurality of manholes, and whose branches and connections are performed at the manholes, the manholes comprising: An optical communication path characterized in that an optical fiber cable within the cable has an extra length for branching and connecting the optical fiber cable. 2. A method of laying an optical communication path using optical fiber cable as a transmission medium, which is installed in an underground network provided with a plurality of manholes, and whose branches and connections are performed at the manholes, the method comprising: A method for laying an optical communication path, characterized in that an extra length is provided in advance in an optical fiber cable, and the optical fiber cable is branched and connected at this extra length.