JPH0949932A - Method for branching and connecting optical fiber cable - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to reduce the labor and cost of the work over the entire part when an optical network is built, to reduce the size and shape over the entire part of respective branching boxes, to eliminate the restriction on the installation place of a branching box as far as possible and to easily constitute a water infiltration detecting sensor. SOLUTION: The remaining parts exclusive of the respective optical fibers (e) constituting optical fiber cables F for a trunk are all cut in so that prescribed extra lengths are assured for the optical fibers (e) in the branching position in mid-way of the optical fiber cables F in this method for branching and connecting the optical fiber cables. Further, only the optical fibers (e) of the number necessary for branching among the respective non-cut optical fibers (e) are cut and thereafter, the optical fiber cables (f) for branching are connected to the cut optical fibers (e).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for branching optical fiber cables to construct an optical network.

[0002]

2. Description of the Related Art FIG. 9 shows an example of a star type optical network.

In the figure, A is a center, B, B, ...
Are data terminals, C, C, ... are branch boxes called closures, F ₁ , F ₂ , F ₃ , ... Are optical fiber cables for trunk lines, and f, f, ... Are optical fiber cables for branching.

Then, for example, the optical signal transmitted from the center A is sent to each of the optical fiber cables F ₁ , F ₂ ,
F _3, while being transmitted through ..., each branch boxes C, C, after being branched at ..., fiber optic cable f for branching, f, ... each data terminal B via, B, sent to ... To be

Optical fiber cables F ₁ , F ₂ , ..., F, f, ... Used for constructing such an optical network.
For example, the one having the configuration shown in FIG. 10 may be used.

This optical fiber cable is of the so-called slot type and has a slot rod a made of polyethylene resin or the like. The slot rod a has spiral (or SZ) grooves (slots) along the axial direction at several locations (five in this example) on the outer periphery.
b are formed, and the tape core wires e are stacked and accommodated in a plurality of layers (5 layers in this example) in each groove b, while the center of the slot rod a has, for example, seven steels. A tension member g formed by twisting wires is embedded.
Then, on the surface of the slot rod a, a press winding layer h made of Al tape or the like is formed in a state of closing each groove b, and further, on the press winding layer h, made of polyethylene resin or the like. A protective sheath i is provided. The symbol j is a tracer mark for identifying the position of each groove b.

The above-mentioned tape core wire e is, for example, as shown in FIG.
As shown in, an optical fiber element consisting of a core and a clad
A plurality of optical fiber core wires q formed by forming a primary coating layer p made of an ultraviolet curable resin on k (in this example, 4
(2) are arranged in parallel, a secondary coating layer r also made of an ultraviolet curable resin is formed and integrated.

In order to construct the optical network shown in FIG. 9 using the slot type optical fiber cables as shown in FIGS. 10 and 11, conventionally, the following branch connection has been performed. It was

Here, in order to simplify the explanation, it is assumed that m tape cores e are evenly branched and connected from the center A to each data terminal B, B, ... And connected to the center A. The first optical fiber cable F _{1 to be used} is n
Suppose we have a tape core e of (n> m).

First, as for the first-stage branch box C close to the center A, as shown in FIG. 12, as the optical fiber cable F ₂ for the main line on the subsequent side, it has (n−m) tape cores. Also, as the optical fiber cable f for branching, one having m tape cores e is prepared.

The optical fiber cables F ₁ , F ₂ ,
With respect to f, the slot rod a is exposed except for the protective sheath i and the press-wound layer h, and the tape core wire e is drawn out, and the drawn tape core wire e is cut in a state where an extra length portion is secured.

Subsequently, the optical fiber cable F for each trunk line
₁ and F ₂ (n−m) number of tape core wires e, and optical fiber cable F ₁ for main line and optical fiber cable f for branching
After each of the m pieces of the respective tape core wires e are fusion-spliced (indicated by X in the figure) at the cut portions, the optical fiber cables F ₁ , F ₂ and f are fixed to the branch box C, and The extra length portion is stored in the branch box C.

Similarly, regarding the branching box C of the next stage, as the optical fiber cable F ₃ for the main line on the subsequent side, one having (n-2m) tape cores is used, and the optical fiber for branching is also used. As the fiber cable f, there are m tape cores.
A branch connection is made using the one having e.

However, the branch connection method as shown in FIG. 12 has the following problems.

Optical fiber cables F ₁ , F ₂ , for the trunk line,
As F ₃ , ..., In the above example, the number of tape cores e is n
Different types such as books, (n−m), (n−2m), ... Must be prepared in advance, and the optical fiber cables F ₁ , F ₂ , F ₃ ,. Unification cannot be achieved. Therefore, the overall cost for constructing an optical network becomes high.

Further, in each branch box C, C, ..., The trunk optical fiber cables F ₁ , F ₂ , F ₃ , ... And the branch optical fiber cables f, f ,. In addition, the optical fiber cables F ₁ and F ₂ , F ₂ and F ₃ , for main lines must be fusion-spliced together, and the number of connection points increases, which makes the connection work troublesome. Moreover, as the number of connection points increases, the connection loss increases accordingly.

In order to improve such inconvenience, in the prior art, a branch connection method as shown in FIG. 13 has also been proposed.

For simplicity of explanation, it is assumed that m tape cores e are evenly branched and connected from the center A to each of the data terminals B, B, ...

As the optical fiber cable F for the trunk line, unlike the branch connection method shown in FIG. 12, different types before and after the branch boxes C, C, ... Are not used. , With 1 tape core
Use a continuous cable of books. Moreover, as the optical fiber cables f, f, ...
Prepare the items with

Next, for the first-stage branch box C close to the center A, for example, in the optical fiber cable F for the trunk line, the slot rod a is exposed except for the protective sheath i and the press winding layer h. Next, of the n tape core wires e, only m tape core wires e necessary for branching are pulled out from the slot rod a and cut. In this case, the slot rod a itself is not cut and is kept in its exposed state.

On the other hand, in the optical fiber cable f for branching, the extra length of the tape core wire e is secured,
The slot rod except for the protective sheath i and the press winding layer h
After exposing a, pull out the tape core wire e.

The optical fiber cable F for each trunk line
And m of each optical fiber cable for branching
After fusion-splicing each other (indicated by X in the figure), the optical fiber cables F and f are fixed to the branch box C, and the extra length portion is stored in the branch box C.

The branch box C _{2 in the} next stage is similarly branched and connected.

[0024]

As described above, in the branch connection method shown in FIG. 13, since only one continuous cable can be used as the optical fiber cable F for the trunk line, an optical network is used. The overall cost of building is cheaper. In addition, each branch box C, C, ...
In the above, it is only necessary to fusion-bond the respective tape core wires e of the optical fiber cable F for the trunk line and the optical fiber cable f for the branch to each other, and the fusion-splicing of the optical fiber cables F for the trunk line is unnecessary. Therefore, there is an advantage that the labor of connection work can be saved and connection loss can be eliminated.

However, even in such a branch connection method, the following problem still remains.

In this method, as the length L of the exposed portion of the slot rod a in the optical fiber cable F for the trunk line is longer, the pull-out length of the tape core wire e to be branched and connected can be secured sufficiently. The longer the length of the tape core wire e pulled out, the more easily the tape core wire e can be cut and the fusion spliced, and the workability is improved.

On the other hand, however, if the length L of the exposed portion of the slot rod a of the optical fiber cable F for the main line is long, the size and shape of each branch box C, C, ... The location where each branch box C, C, ... Is installed is restricted, and there is an adverse effect such as an obstacle.

On the contrary, if the length L of the exposed portion of the slot rod a of the optical fiber cable F for the trunk line is shortened, the size and shape of each of the branch boxes C, C, ... Since the pull-out length of the tape core wire e becomes short, the workability at the time of cutting the tape core wire e and the fusion splicing is deteriorated.

Further, in the branch connection method shown in FIG. 13, the uncut tape core wire e of the optical fiber cable F for the main line is wound around the slot rod a, so that there is a sufficient extra length portion. Cannot be secured.

Therefore, for example, it is difficult to construct the water immersion detection sensor s by utilizing the extra length portion of one tape core wire e of the optical fiber cable F for the trunk line.

That is, in this water immersion detection sensor s, a polymer absorbent is provided around one tape core wire e of the optical fiber cable F for the trunk line, and the polymer absorbent expands due to the water immersion to cause the tape core to expand. When the line e is bent, the bending loss increases, so that the water intrusion is detected. However, the branch connection method shown in FIG. 13 cannot secure a sufficient extra length portion. As shown in the figure, after cutting one tape core wire e, the tape core wire for constituting the water immersion detection sensor s is separately fusion-bonded.
It took a lot of time to construct s.

The present invention has been made in order to solve the above-mentioned problems, and it aims to reduce the labor and cost of the whole construction when constructing an optical network, and to reduce the size and shape of each branch box as a whole. It is an object to reduce the size of the branch box so that the restriction on the installation location of the branch box can be removed as much as possible, and further, the inundation detection sensor can be easily configured.

[0033]

The present invention adopts the following constitution in order to solve the above problems.

That is, in the optical fiber cable branching and connecting method of the present invention, each optical fiber constituting the optical fiber cable has a predetermined extra length at the branching position in the middle of the trunk optical fiber cable. In addition, all the remaining parts except the optical fiber are cut, and further, among the uncut optical fibers, only the number of optical fibers necessary for branching are cut, and then the cut optical fiber is split. Connect the optical fiber cable.

[0035]

FIG. 1 is a schematic configuration diagram showing a portion of a branch box C when the optical network as shown in FIG. 9 is configured by applying the branch connection method of the present invention.

In the figure, reference numeral F is a trunk optical fiber cable, and f is a branching optical fiber cable.
In this example, both cables F, f are of the slot type shown in FIG. 10, and are optical fiber cables F for trunk lines.
Uses one continuous cable with n tape conductors. Also in this example, if m tape cores e are evenly branched and connected for each data terminal, the optical fiber cable f for each branch is m
Those having a tape core e of a book (m <n) are used. Further, in this embodiment, the tape core wire e corresponds to the optical fiber in the claims.

Further, in the branch box C, the slot rod a and the tension member g are cut except for the n tape cores of the optical fiber cable F for the main line, and the optical fiber cables F and f are cut. end of the cable clamp w _1, tension members g of each cable F, f are fixed to respective branching box C by the tension member clamp w _2.

The optical fiber cable F for the trunk line
Of the n tape cores e, (n−m) tape cores e pass through the branch box C as they are with the extra length secured, and the remaining m tape cores e is connected to m tape cores e of the optical fiber cable f for branching.

Next, one embodiment of the branch connection method of the present invention will be described with reference to FIGS.

First, as the optical fiber cable F for the main line, one continuous cable having n tape cores e is used. Also, the optical fiber cable for each branch f
As the above, ones each having m tape cores e are prepared.

As for the optical fiber cable F for the trunk line, as shown in FIG. 2, at the branch position in the middle of the wiring, a predetermined length is ensured so that the extra length L ₀ of the tape core wire e is sufficiently secured. The slot rod a is exposed by removing the protective sheath i and the press-winding layer h by the amount.

Next, all of the n tape core wires e wound around the exposed slot rod a are slot rod a.
The remaining slot rods a are exposed while the n cores of the tapes e are left as they are and the fixing allowance L ₁ for fixing the optical fiber cable F to the branch box C is secured. Cut off together with the tension member g. Further, after the tension member g is exposed by a predetermined length except the end portion of the slot rod a in the fixed margin L ₁ , the cut portions of the tension member g are butted against each other.

Subsequently, as shown in FIG. 3, the press winding layer h
After the ground wire u for electrically connecting the two is fixed by using the PVC tape y, the split sleeve v having the shape shown in FIG. 4 is put on the cut portion and fixed by the adhesive. This is to prevent the tape core wire e from easily moving in the axial direction along the groove b of the slot rod a. When the split sleeve v is attached, as shown in FIG. 5, the ground wire u is pulled out to the outside through a through hole v ₁ provided at one position of the split sleeve v. Further, the PVC tape y is wound around both ends of the split sleeve v.

Next, as shown in FIGS. 6 and 8, the portion of the protective sheath i of the optical fiber cable F for the trunk line is fixed by the cable clamp w ₁ , and the portion where the tension member g is exposed is the tension member. Tighten each with the clamp w ₂ . As a result, the optical fiber cable F for the main line is connected to the branch box C via the clamps w ₁ and w _2.
Fixed to.

On the other hand, as shown in FIG. 7, the branching optical fiber cable f has a protective sheath i and a protective sheath i so that the extra length L ₂ of the tape core wire e is sufficiently secured at one end thereof. After the slot rod a is exposed except for the press winding layer h, the tape core wire e is pulled out, and then the fixing allowance L ₃ for fixing the optical fiber cable f to the branch box C ₃
The remaining slot rods exposed
Cut a together with tension member g. Further, the tension member g is exposed by a predetermined length except for the end portion of the slot rod a in the fixed margin L ₃ .

Then, as shown in FIG. 8, the portion of the protective sheath i of the optical fiber cable f is fastened by the cable clamp w ₁ , and the portion where the tension member g is exposed is fastened by the tension member clamp w ₂ . To do. As a result, the branching optical fiber cable f is fixed to the branching box C via the clamps w ₁ and w ₂ .

Then, the optical fiber cable F for the trunk line
Of n tape cores e, the number required for branching (m in this example)
Of the optical fiber cable f for branching are fusion-spliced (indicated by X in FIG. 8).

Then, the branch connection is completed by winding and storing the extra length portion of the tape core wire e of each of the trunk and branch optical fiber cables F and f around the tray t attached to the branch box C.

In the branch connection method of the present invention, for the uncut tape core wire e of the optical fiber cable F for the main line,
Since it is possible to secure a sufficient extra length portion, it is not necessary to separately fusion-bond the tape core wire for configuring the water immersion detection sensor s as in the conventional case shown in FIG. 13, and the broken line in FIG. As shown in, the extra length portion can be used as it is to easily configure the water immersion detection sensor s.

In the above embodiment, the tape core wires e are fusion-bonded to each other. However, in the case where some of the optical fiber wires q forming the tape core wires e are connected to each other. However, the present invention can be applied. Further, in the present example, the optical fiber cables F and f have been described as being slot type, as shown in FIG. 10, but the present invention is not limited to this, and optical fiber core wires are twisted and assembled. Of course, it can be applied to a so-called strand type. In that case, the optical fiber core wire corresponds to the optical fiber in the claims.

[0051]

According to the present invention, the following effects can be obtained.

(1) Since one continuous cable is used as the optical fiber cable for the trunk line, fusion splicing of the optical fiber cables for the trunk line is unnecessary, and an optical network is constructed at a relatively low cost. be able to.

(2) Regarding the optical fiber cable for the trunk line, although the sufficient length of the optical fiber can be secured, the cable can be fixed in a short length, so that the optical fiber can be cut or fused. Can be easily performed, the size and shape of the entire branch box can be reduced, and the branch case can be installed in a relatively free place.

(3) Since a sufficient extra length can be secured for the uncut optical fiber of the optical fiber cable for the trunk line, the flood detection sensor can be easily constructed by using the extra length as it is.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing a part of a branch box when an optical network is configured by applying a branch connection method of the present invention.

FIG. 2 is a front view showing a procedure of a branch connection method of the present invention, showing a state in which a tape core wire is pulled out from a slot rod and a slot rod and a tension member are cut in a trunk optical fiber cable. Is.

FIG. 3 is a front view showing a procedure of a branch connection method of the present invention, showing a state in which a PVC tape is wound around a place where a slot rod is cut and a ground wire is attached.

FIG. 4 is a perspective view of a split sleeve used in the branch connection method of the present invention.

5 is a perspective view showing a procedure of the branch connection method of the present invention, in a state in which the split sleeve of FIG. 4 is covered on the optical fiber cable.

FIG. 6 is a perspective view showing a procedure of a branch connection method of the present invention, in a state where one end of an optical fiber cable for a trunk line is fastened with a clamp.

FIG. 7 is a front view showing a procedure of the branch connection method of the present invention, showing a state in which a tape core wire is pulled out from the slot rod and the slot rod and the tension member are cut in the branch optical fiber cable. Is.

FIG. 8 is a front view showing a procedure of a branch connection method of the present invention, showing a state in which each branching optical fiber cable for a trunk line is attached to a branch box.

FIG. 9 is a configuration diagram of an optical network.

FIG. 10 is a cross-sectional view showing an example of a slot type optical fiber cable.

11 is a cross-sectional view of a tape core wire forming the optical fiber cable of FIG.

FIG. 12 is an explanatory diagram of a conventional branch connection method.

FIG. 13 is an explanatory diagram of another conventional branch connection method.

[Explanation of symbols]

F ₁ , F ₂ , F ₃ , F ... Optical fiber cable for trunk line, C
… Branch box, f… Optical fiber cable for branching, a…
Slot rod, b ... groove (slot), g ... tension member, e ... ribbon, w ₁ ... Cable clamp, w ₂ ... tension members clamp.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Mitsumitsu Ueda 4-3 Ikejiri, Itami City, Hyogo Prefecture Mitsubishi Cable Industries, Ltd. Itami Works

Claims (1)

[Claims] 1. A method for branching and connecting an optical fiber cable comprising a plurality of optical fibers, wherein each optical fiber constituting the optical fiber cable is at a branch position in the middle of the trunk optical fiber cable. In order to ensure a predetermined extra length, all the remaining parts except the optical fiber are cut, and further, among the uncut optical fibers, after cutting only the number of optical fibers necessary for branching,
An optical fiber cable branching and connecting method, characterized in that a branching optical fiber cable is connected to the cut optical fiber.