JP3108335B2 - Branch connection method of optical fiber cable - Google Patents

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 and connecting 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 FIG. 1, A is a center, B, B,.
Are data terminals, C, C,... Are branch boxes called closures, F ₁ , F ₂ , F ₃ ,... Are trunk optical fiber cables, and f, f,.

[0004] For example, the optical signal transmitted from the center A is divided into the main optical fiber cables F ₁ , F ₂ ,
F ₃ ,..., And after being branched in each branch box C, C,..., Transmitted to each data terminal B, B,. Can be

[0005] Optical fiber cables F ₁ , F ₂ , ..., f, f, ... used to construct such an optical network.
For example, the configuration shown in FIG. 10 may be used.

This optical fiber cable is of a so-called slot type and has a slot rod a made of polyethylene resin or the like. The slot rod a has a spiral or SZ-shaped groove (slot) extending along the axial direction at several places (five places in this example) on the outer peripheral portion thereof.
In each groove b, a plurality of layers (five layers in this example) of tape cores e are stacked and housed, while the center of the slot rod a is, for example, seven steels. A tension member g in which wires are twisted is embedded.
Then, on the surface of the slot rod a, a holding roll layer h made of Al tape or the like is formed in a state where each groove b is closed, and on the holding roll layer h, a polyethylene resin or the like is formed. A protective sheath i is provided. The symbol j is a tracer mark for specifying the position of each groove b.

The above-mentioned tape core e is, for example, as shown in FIG.
As shown in the figure, an optical fiber consisting of a core and a clad
A plurality of optical fiber cords q (4 in this example) constituted by forming a primary coating layer p made of an ultraviolet curable resin on
In this state, the secondary coating layer r also made of an ultraviolet-curable resin is formed and integrated in a state where the pieces are arranged in parallel.

In order to construct the optical network shown in FIG. 9 by using a slot type optical fiber cable as shown in FIGS. 10 and 11, the following branch connection is conventionally performed. Was.

Here, in order to simplify the explanation, it is assumed that m tape cores e are equally branched and connected from the center A for each data terminal B, B,. the first optical fiber cable F ₁ being the, n the
It is assumed that the tape has a core wire e of (n> m).

First, as shown in FIG. 12, the first branch box C adjacent to the center A has (n−m) tape cores as the optical fiber cable F ₂ for the rear trunk line. A cable having an m number of tapes e is prepared as a branch optical fiber cable f.

Then, each of the optical fiber cables F ₁ , F ₂ ,
With respect to f, the tape core e is drawn by exposing the slot rod a except for the protective sheath i and the presser winding layer h, and the drawn tape core e is cut in a state where the extra length is secured.

Subsequently, the optical fiber cable F for each trunk line
_1, F ₂ of the (n-m) present in ribbon e each other and the optical fiber cable F ₁ and the optical fiber cable f of branch for trunk
After each of the m tape cores e is fusion-spliced (indicated by a mark x in the drawing) at the cut portion, each of the optical fiber cables F ₁ , F ₂ , f is fixed to the branch box C, The extra length is stored in the branch box C.

Similarly, for the branch box C in the next stage, the optical fiber cable F ₃ for the trunk line on the rear side having a (n−2m) number of tapes is used as the optical fiber cable F _3. As the fiber cable f, m tape cores
Branch connection is performed using the one having e.

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

Each of the optical fiber cables F ₁ , F ₂ ,
F _3, ... as in the above example the number of ribbon e is n
, (N−m), (n−2m),... Must be prepared in advance, and different types of optical fiber cables F ₁ , F ₂ , F ₃ ,. Unification is not possible. For this reason, the overall cost for constructing an optical network increases.

In each of the branch boxes C, C,..., The optical fiber cables F ₁ , F ₂ , F ₃ ,... For the trunk line and the optical fiber cables f, f,. in addition to the optical fiber cable F ₁ and F ₂ for the mains, F ₂ and F _3, ... to each other also must take into fusion splicing, it takes time only connection work amount that connecting points is increased. In addition, as the number of connection points increases, the connection loss increases accordingly.

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

Here, for the sake of simplicity, it is assumed that m tape cores e are equally branched and connected from the center A for each data terminal B, B,.

As the optical fiber cable F for the trunk line, different types of cables are not used before and after each of the branch boxes C, C,... As in the branch connection method shown in FIG. One with n tape cores
Use a continuous cable of books. The optical fiber cables f, f,... For each branch include m tape cores e.
Are prepared.

Next, for example, with respect to the first branch box C close to the center A, the slot rod a of the optical fiber cable F for the trunk is exposed except for the protective sheath i and the holding layer h. Next, of the n tape cores e, only m tape cores e required for branching are pulled out from the slot rod a and cut. In this case, the slot rod a itself is kept in its exposed state without cutting.

On the other hand, with respect to the branching optical fiber cable f, the extra length of the tape cord e is secured.
Slot rod except for its protective sheath i and holding layer h
After exposing a, pull out the tape core wire e.

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

[0023] Also with respect to the next stage of the branch box C _2, branches in the same manner, the connection is made.

[0024]

As described above, in the branch connection method shown in FIG. 13, only one continuous cable can be used as the trunk optical fiber cable F. The overall cost of building is lower. Each branch box C, C,...
In the above, it is only necessary to fusion-splice each of the core fibers e of the trunk optical fiber cable F and the branch optical fiber cable f, and it is unnecessary to fusion-splice the trunk optical fiber cables F. Therefore, there is obtained an advantage that connection work is omitted and connection loss is eliminated.

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

According to this method, in the trunk optical fiber cable F, the longer the length L of the exposed portion of the slot rod a is, the longer the length of the tape core e to be branched and connected can be secured. If the length of the tape core wire e is long, the tape core wire e can be easily cut or fusion-spliced, resulting in good workability.

On the other hand, if the length L of the exposed portion of the slot rod a of the optical fiber cable F for the trunk line is long, the overall size and shape of each of the branch boxes C, C,. There are adverse effects such as the location of each branch box C, C,.

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

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

For this reason, for example, it is difficult to form the water intrusion detection sensor s by utilizing the extra length of one tape core e of the trunk optical fiber cable F.

That is, in the water immersion detection sensor s, a polymer absorber is provided around one tape core e of a main optical fiber cable F, and the polymer absorber expands due to water immersion to expand the tape core. Although the inundation is detected by increasing the bending loss when the line e is bent, the branch connection method shown in FIG. 13 cannot secure a sufficient extra length. As shown in the figure, after cutting one tape core e, a tape core for constituting the water intrusion detection sensor s is separately fused and connected.
It was extremely time-consuming to construct s.

The present invention has been made to solve the above-mentioned problems, and aims to reduce the labor and cost of the overall construction when constructing an optical network, and to reduce the size and shape of the entire branch box. It is an object of the present invention to reduce the size, to reduce the restriction on the installation place of the branch box as much as possible, and to easily configure a flood detection sensor.

[0033]

The present invention employs the following structure in order to solve the above-mentioned problems.

That is, in the branch connection method for an optical fiber cable according to the present invention, at the branch position in the middle of the trunk optical fiber cable, each optical fiber constituting the optical fiber cable is provided with a predetermined extra length. in, along with all cutting the remaining portion excluding the optical fiber cutting
With the split sleeve over the end, the optical fiber and the residual
At the cut end with the adhesive together with the split sleeve.
By cutting the cut ends, the excess length of each uncut optical fiber is slackened, and only the number of optical fibers required for branching out of each uncut optical fiber is cut. After that, a branch optical fiber cable is connected to the cut optical fiber.

[0035]

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

In the figure, reference symbol F is a trunk optical fiber cable, and f is a branch optical fiber cable.
In this example, both cables F and f are of the slot type shown in FIG.
Uses a single continuous cable with n tape cores. Also, in this example, if the m tape ribbons e are equally branched and connected for each data terminal, as the optical fiber cable f for each branch, m
A tape having a number (m <n) of tape cores e is used. In this embodiment, the tape core e corresponds to the optical fiber in the claims.

In the branch box C, the slot rods a and the tension members g are cut except for the n tape cores of the optical fiber cable F for the trunk line. 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.

Then, the optical fiber cable F for the trunk line is
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 e is connected to the m tape cores e of the branch optical fiber cable f.

Next, an 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 trunk line, one continuous cable having n tape cores e is used. Also, the optical fiber cable f for each branch
Are prepared, each having m tape cores e.

Then, as shown in FIG. 2, the predetermined length of the optical fiber cable F for the trunk line is set such that the extra length L ₀ of the tape core e is sufficiently secured at the branch position in the middle of the wiring. Then, the protective sheath i and the holding layer h are removed to expose the slot rod a.

Next, the n tape cores e wound around the exposed slot rod a are all attached to the slot rod a.
Together pulled out, ribbon e thereof n book intact, while securing the fixed allowance L ₁ for fixing the optical fiber cable F to the branch box C, and the remaining slots rod a exposed Cut off together with the tension member g. Furthermore, matching after exposing the tension member g predetermined length except for the end of the slot rod a in fixed allowance L _1, the cut portion of the tension member g each other.

Subsequently, as shown in FIG.
After fixing the ground wire u for electrically connecting them with each other using a PVC tape y, a split sleeve v having the shape shown in FIG. 4 is put on the cut portion and fixed with an adhesive. This is to prevent the tape cord e from easily moving in the axial direction along the groove b of the slot rod a. When installing the split sleeve v, as shown in FIG. 5, the ground wire u is to be drawn out to the outside through the through hole v ₁ provided in one location of the split sleeve v. Further, a PVC tape y is wound around both ends of the split sleeve v.

Next, as shown in FIGS. 6 and 8, the cable clamp w ₁ a portion of the protective sheath i of the optical fiber cable F for trunk, also tension member portions tension member g is exposed to fastened respectively by clamp w _2. Thus, the optical fiber cable F is the clamp for mains w _1, branching via the w ₂ Box C
Fixed to

On the other hand, as shown in FIG. 7, a protective sheath i and a branch optical fiber cable f are provided so that the extra length L ₂ of the tape cord e is sufficiently secured at one end thereof. After exposing the slot rod a excluding the presser winding layer h and extracting the tape core e, a fixing allowance L ₃ for fixing the optical fiber cable f to the branch box C is drawn.
With the remaining slot rod exposed
a is cut off together with the tension member g. Furthermore, exposing the tension member g predetermined length except for the end of the slot rod a in fixed allowance L _3.

[0046] Then, as shown in FIG. 8, by the cable clamp w ₁ part of the protective sheath i of the fiber optic cable f, also fastening respectively a portion tension member g is exposed by the tension member clamp w ₂ I do. Thereby, the branch optical fiber cable f is fixed to the branch box C via the clamps w ₁ and w ₂ .

Subsequently, the main optical fiber cable F
Number required for branching out of n tape cores e (m in this example)
Are cut off, and these tape cores e are fusion-spliced to the m tape cores e of the optical fiber cable f for branching (indicated by X in FIG. 8).

Then, the extra length of the core fiber e of each of the optical fiber cables F and f for the trunk line and the branch is wound and stored on the tray t attached to the branch box C, thereby completing the branch connection.

In the branch connection method of the present invention, the uncut tape core e of the optical fiber cable F for the trunk is
Since a sufficient extra length can be secured, there is no need to separately fuse and bond a tape core for forming the water immersion detection sensor s as in the conventional case shown in FIG. As shown by, it is possible to easily configure the inundation detection sensor s by using the extra length as it is.

In the above embodiment, the tape cores e are fusion-spliced. However, in the case where some of the optical fiber strands q constituting the tape cores e are connected to each other. However, the present invention is applicable. Further, in this example, the optical fiber cables F and f are described as being of the slot type as shown in FIG. 10, but the present invention is not limited to this, and the optical fiber cables are twisted and assembled. Of course, the present invention 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 a single continuous cable is used as the trunk optical fiber cable, fusion splicing of the trunk optical fiber cables is unnecessary, and an optical network is constructed relatively inexpensively. be able to.

(2) Regarding the trunk optical fiber cable, although the extra length of the optical fiber can be secured, the cable can be fixed only to a short length, so that the optical fiber is cut or fusion spliced. Can be performed easily, 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) A sufficient extra length of the uncut optical fiber of the trunk optical fiber cable can be secured, so that the water intrusion detection sensor can be easily configured by using the extra length as it is. (4) Cutting off all the remaining parts except the optical fiber
First, put a split sleeve on the cut end
And the remaining part at the cutting end together with the split sleeve
Since fixed by the adhesive, the optical fiber with respect to the remaining portion
Thus, it can be prevented from easily moving in the axial direction.

[Brief description of the drawings]

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

FIG. 2 is a front view showing a procedure of a branch connection method according to the present invention, in which a core fiber is pulled out from a slot rod and a slot rod and a tension member are cut off in an optical fiber cable for a trunk line. It is.

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

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

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

FIG. 6 is a perspective view showing a procedure of a branch connection method according to 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 a branch connection method according to the present invention, in a branch optical fiber cable, in which a tape core is drawn out from a slot rod and a slot rod and a tension member are cut. It is.

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

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

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

FIG. 11 is a cross-sectional view of a tape core constituting the optical fiber cable of FIG. 10;

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 ... Branch optical fiber cable, a ...
Slot rod, b ... groove (slot), g ... tension member, e ... ribbon, w ₁ ... Cable clamp, w ₂ ... tension members clamp.

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Masumitsu Ueda 4-3 Ikejiri, Itami-shi, Hyogo Prefecture, Itami Works, Mitsubishi Electric Wire & Cable Co., Ltd. (56) References JP-A-8-43639 (JP, A) JP-A-58-169114 (JP, A) JP-A-8-160231 (JP, A) JP-A-8-334631 (JP, A) JP-A-63-236938 (JP, A) JP-A-4-160350 (JP, A) , A) JP-A-3-13905 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G02B 6/00 G02B 6/24 G02B 6/46 H02G 15/08

Claims (1)

(57) [Claims] 1. A method for branching and connecting an optical fiber cable comprising a plurality of optical fibers, wherein each of the optical fibers constituting the optical fiber cable is provided at a branch position in the middle of the trunk optical fiber cable. Cut all the remaining parts except for the optical fiber so that the specified extra length is secured , and split three at the cut end.
Cut the optical fiber and the remaining part
At the end, the entire split sleeve is fixed with an adhesive , and the cut ends are abutted against each other to loosen the excess length of each uncut optical fiber. After cutting only the required number of optical fibers,
An optical fiber cable branch connection method, comprising connecting an optical fiber cable for branching to the cut optical fiber.