JP4120957B2 - Structure and method for reinforcing fusion splice of optical fiber cord - Google Patents

Description

  The present invention relates to a fusion splicing portion reinforcing structure and a reinforcing method for an optical fiber cord that reinforces a fusion splicing portion of optical fiber cords in which a tensile strength fiber is attached to the outer periphery of an optical fiber core and a sheath is provided on the outer side .

  An optical fiber cord is a structure in which a tensile strength material is attached to an optical fiber core, and a sheath is provided. An example of an optical fiber cord having a structure using a tensile strength fiber such as an aramid fiber (Kevlar) as a tensile strength material is shown. This is as shown in FIG. This optical fiber cord 1 has an aramid fiber (single-core loose-tube core) 2 on the outer periphery of a single-core optical fiber (single-core loose tube core) 2 in which a single optical fiber (0.25 mm UV strand) 3 is accommodated in a pipe 4. This is a structure in which a tensile strength fiber 5 such as Kevlar) is added and a sheath 6 such as PVC (vinyl chloride) is applied to the outside thereof.

By the way, if the optical fiber cores 2 are merely fusion-connected, the optical fiber core wire 2 can be inserted as it is into the fusion-reinforcing sleeve that covers the fusion-bonded portion of the optical fiber. It is relatively easy to reinforce the part and reinforce the entire connection part.
However, when the optical fiber cords 1 containing the tensile strength fibers are fused and connected, it is necessary to hold the tensile strength fibers at the end of the cord. In general, this work often involves folding the tensile strength fiber outward and fixing it to the end of the cord. However, in order to keep the strength of the fusion spliced portion sufficiently high, the tensile strength fiber 5 of the optical fiber cord 1 on both sides of the fusion spliced portion is used. It is necessary to keep the sheaths 6 and the sheaths 6 from each other. However, it is not easy to stop the fiber cord so as to maintain the original mechanical strength.

  For example, as shown in FIG. 13, the fusion-bonding sleeve 7 is put on the fusion splicing portion between the optical fibers 3, and the left and right optical fiber cords 1 (one optical fiber cord is 1A and the other optical fiber cord is 1B). The tensile strength fibers 5 and 5 are superimposed on the fusion reinforcing sleeve 7 and a reinforcing member 8 is disposed in the vicinity of the fusion reinforcing sleeve 7 along the longitudinal direction. A protective pipe made of vinyl resin or the like may be covered, and the adhesive 10 may be filled into the protective pipe 9 in some cases. As a result, the fusion spliced portion of the optical fiber 3 is directly reinforced by the fusion reinforcing sleeve 7 and the tensile strength fibers 5 and the sheaths 6 of the optical fiber cords 1 (1A, 1B) on both sides are held together. The reinforcement of the fusion splicing portion becomes sufficiently solid.

However, in the conventional method for reinforcing the fusion spliced portion of the optical fiber cord, the left and right tensile strength fibers 5 once separated from the pipe 4 are overlapped on the fusion reinforcement sleeve 7 and the tensile strength fiber such as Kevlar is used. Since 5 is scattered and not easily bundled, the operation of housing the tensile strength fiber 5 together with the reinforcing member 8 in the protective pipe 9 is extremely complicated. Further, since the reinforcing member 8 is arranged, the outer diameter of the fusion spliced portion of the optical fiber cord 1 becomes considerably larger than that of the optical fiber cord 1 itself, and the request for compactness cannot be met.
In addition, a hard resin molded product is widely used as the reinforcing member 8. Since the reinforcing member 8 has a shape corresponding to the outer diameter of the optical fiber cord 1, it depends on the type of the outer diameter of the optical fiber cord. Therefore, there is a problem that it is necessary to mold reinforcing members having different shapes, and a plurality of types of molds are required, which increases costs.

  Further, the conventional fusion splicing portion reinforcing structure has an asymmetric cross-sectional shape due to the presence of the reinforcing member 8, and the adhesive 10 filled in the protective pipe 9 is not uniformly distributed around the optical fiber 3. . That is, the amount of the adhesive 10 filled differs between the side where the reinforcing member 8 of the optical fiber 3 is disposed and the opposite side. Therefore, when the adhesive 10 is cured in the protective pipe 9, anisotropy occurs in the curing shrinkage of the adhesive 10, and thus non-uniform stress is generated in the optical fiber 3, and in some cases, the optical fiber 3 may be broken. .

  The present invention has been made in order to eliminate the above-mentioned conventional drawbacks, and can easily process the left and right tensile strength fibers and can easily reinforce the fusion spliced portion between the optical fiber cords at a low cost. In addition, an object of the present invention is to provide a fusion splicing portion reinforcing structure and a reinforcing method of an optical fiber cord, in which the fusion splicing portion can be made compact and non-uniform stress does not act on the optical fiber. .

According to the first aspect of the present invention for solving the above-mentioned problems, fusion of optical fiber cords in which a tensile fiber is added to the outer periphery of a loose tube type optical fiber in which an optical fiber is housed in a pipe and a sheath is provided on the outer periphery thereof. In the fusion splicing portion reinforcing structure of the optical fiber cord that reinforces the connecting portion,
Cover the fusion splicing portion of the optical fibers exposed from the optical fiber cores of the optical fiber cords on both sides with a fusion reinforcing sleeve,
Covering the fusion reinforcing sleeve with a reinforcing tube in such a manner as to straddle the optical fiber core coating portion of one optical fiber cord from the optical fiber core coating portion of the other optical fiber cord,
The first heat-shrinkable tube by interposing one of tensile strength fiber to the outer circumference of the reinforcing tube put in a manner that does not hide the distal end portion of the tensile strength fiber,
A second heat-shrinkable tube by interposing the other tensile strength fibers to the outer periphery of the first heat-shrinkable tube to be brought in a manner that does not hide the distal end portion of the tensile strength fiber,
The both ends of the first heat shrinkable tube and the second heat shrinkable tube are bonded and fixed to both ends of the reinforcing tube, the left and right tensile strength fibers on the reinforcing tube, and the sheath end of the optical fiber cord .

According to a second aspect of the present invention, the spiral tube is wound on the second heat-shrinkable tube of the first aspect in such a manner as to extend from the sheath portion of one optical fiber cord to the sheath portion of the other optical fiber cord. Further, the third heat shrinkable tube as the outermost layer is covered thereon so as to extend from the sheath portion of one optical fiber cord to the sheath portion of the other optical fiber cord.

Claim 3, the third heat-shrinkable tube in the claims 2, characterized in that an adhesive with heat shrinkable tube with adhesive applied to the inner surface.

The invention of claim 4 reinforces the fusion spliced portion of the optical fiber cords in which the tensile fiber is attached to the outer periphery of the loose tube type optical fiber core in which the optical fiber is housed in the pipe and the sheath is provided on the outer periphery thereof. In the method of reinforcing the fusion splicing portion of the optical fiber cord for reinforcing the fusion splicing portion,
Cover the fusion spliced portion of the fibers exposed from the optical fiber cores of the optical fiber cords on both sides with a fusion reinforcing sleeve,
A reinforcing tube is placed on the fusion reinforcing sleeve in such a manner as to extend from the optical fiber core covering portion of one optical fiber cord to the optical fiber core covering portion of the other optical fiber cord. Then, the first heat-shrinkable tube previously slidably covered on one optical fiber cord is slid to the fusion splicing side and reinforced from above the one tensile fiber. Cover the tube in a manner that does not hide the tip of the tensile strength fiber ,
Next, the other optical fiber cord side tensile fiber is attached to the outer periphery of the first heat shrinkable tube, and then the second heat shrinkable tube previously slidably covered on the other optical fiber cord is melted. It is allowed in a manner which does not hide the distal end portion of the tensile strength fiber to a first heat-shrinkable tube by sliding the destination connection portion side from the top of the other tensile strength fiber,
The both ends of the first heat shrinkable tube and the second heat shrinkable tube are bonded and fixed to both ends on the reinforcing tube, the left and right tensile strength fibers on the reinforcing tube, and the sheath end of the optical fiber cord .

Claim 5, in claim 4, after covering the second heat-shrinkable tube, the second of the other spiral tube from the sheath portion of one of the optical fiber cord on the heat-shrinkable tube of the sheath of the optical fiber cord Wrap in a manner that spans the part, and then cover the third heat shrinkable tube as the outermost layer in a manner that spans from the sheath part of one optical fiber cord to the sheath part of the other optical fiber cord. It is characterized by.

  According to the present invention, when the tensile strength fibers of the left and right optical fiber cords are processed, the first heat shrinkable tube or the second heat shrinkable tube is slid and held at the central portion of the reinforcing tube covered with the fusion reinforcing sleeve. Since the tensile strength fibers that are easily separated are automatically attached to and held by the outer periphery of the reinforcing tube, the treatment of the tensile strength fibers that are likely to be loosened is less likely to entangle the fibers and disrupt the fiber layer. It becomes extremely easy and workability is remarkably improved.

In addition, the tensile strength fibers of each optical fiber cord that has been spliced together are bonded and fixed to each other on the outer peripheral surface of the reinforcing tube, making it easy to hold the tensile strength fibers together. Workability is improved and mechanical strength is improved as compared with the conventional method for holding fibers apart.
In addition, since the adhesive that bonds the tensile strength fiber does not directly adhere to the optical fiber housed in the reinforcing tube, the optical fiber has an adverse effect on the optical fiber, resulting in partially uneven stress. There is no fear of causing distortion, and the optical fiber can be prevented from being adversely affected such as breakage and light loss.

Since the tensile strength fibers on both sides are bonded and fixed to each other on the outer peripheral surface of the reinforcing tube, the heat shrinkable tube (third heat shrinkable tube) is used as a member that holds the sheaths of the optical fiber cords on both sides. Can be used.
The method of covering the heat-shrinkable tube is extremely easy as an operation for holding the sheaths of the optical fiber cords in comparison with the method of covering the protective pipe and filling the inside thereof with an adhesive. In addition, since the reinforcing member necessary for the protective pipe is not necessary, not only the outer diameter of the fusion splicing portion is made compact, but also a die for manufacturing the reinforcing member is not required, and the cost is greatly reduced. be able to. Moreover, since it is fixed by a heat-shrinkable tube (third heat-shrinkable tube), unlike the case of the protective pipe, the next process can be performed without waiting for the adhesive to harden, and workability is improved.

  Hereinafter, a fusion splicing portion reinforcing structure and a reinforcing method of an optical fiber cord embodying the present invention will be described with reference to the drawings.

  FIG. 1 is a sectional view of a fusion splicing portion reinforcing structure 30 for an optical fiber cord according to an embodiment of the present invention, and FIG. The structures of the left and right optical fiber cords 1 (one optical fiber cord is denoted by 1A and the other optical fiber cord is denoted by 1B) are as shown in FIG. 10, and one optical fiber (0.25 mm UV element) Wire) 3 and a tensile strength fiber 5 such as aramid fiber (Kevlar) is attached to the outer periphery of a single optical fiber core wire (single-core loose tube core wire) 2 in which pipe 3 is accommodated in pipe 4, and PVC (chloride) (Vinyl) or the like. An example of specific dimensions of the optical fiber cord 1 is as follows. The outer diameter of the optical fiber core wire 2 (outer diameter of the pipe 4) is 0.9 mm, and the outer diameter of the optical fiber cord 1 (outer diameter of the sheath 6). Is 2.0 mm.

The optical fiber 3 exposed from the optical fiber core 2 of one optical fiber cord 1 (1A) and the optical fiber 3 exposed from the optical fiber core 2 of the other optical fiber cord 1 (1B) are fused. The fusion-bonding sleeve 7 is put on the fusion-bonded portion. This fusion reinforcing sleeve 7 is of a commercially available hot melt type in which the inner surface melted and softened when heated is melt bonded to the fusion connection portion and the outer periphery in the vicinity thereof to protect the fusion connection portion. A reinforcing tube 11 having an outer diameter of 2 mm is put on the outer periphery of the fusion reinforcing sleeve 7.
This reinforcing tube 11 is formed from the pipe 4 portion (optical fiber core coating portion) of the optical fiber core wire 2 of one optical fiber cord 1A to the pipe 4 portion (optical fiber) of the optical fiber core wire 2 of the other optical fiber cord 1B. The adhesive wire 25 is applied to a gap portion between both ends of the reinforcing tube 11 and the sheath ends 6a of the left and right optical fiber cords 1 so that the reinforcing tube 11 Both ends are fixed to the sheath 6 portion of the optical fiber cord 1. Then, the first heat-shrinkable tube 13 is placed on the outer periphery of the reinforcing tube 11 with the tensile fiber 5 on one optical fiber cord 1A side interposed, and the other optical fiber cord is placed on the outer periphery of the first heat-shrinkable tube 13. The second heat shrinkable tube 14 is covered with the tensile strength fiber 5 on the 1B side.
Further, after the spiral tube 26 is wound and covered in such a manner as to extend from the sheath 6 portion of one optical fiber cord 1A to the sheath 6 portion of the other optical fiber cord 1B, an outermost layer is formed thereon. For example, the 3rd heat contraction tube 16 which apply | coated the adhesive agent to the inner surface is covered in the aspect over the sheath 6 part of the other optical fiber cord 1B from the sheath 6 part of one optical fiber cord 1A.

Next, an example of a procedure for obtaining the above-mentioned fusion splicing structure for the optical fiber cord will be described with reference to FIGS.
(1-1) First, as shown in FIG. 3A, two reinforcing cords 21A and 21B having an outer diameter of 2 mm are prepared. For example, the length of one reinforcing cord 21A is 1140 mm, and the length of the other reinforcing cord 21B is 2180 mm. Each reinforcing cord 21 (21A, 21B) has a structure in which the optical fiber 3 is removed from the optical fiber cord 1 shown in FIG. 10, as shown in FIG. Next, as shown in FIG. 4, the first heat-shrinkable tube 13 having an outer diameter of 2.5 mm cut to 30 mm, for example, is placed on one reinforcing cord 21A. Further, the sheath 6 having a length of, for example, 38 mm is peeled off at the distal end side, and the inner pipe 4 is cut at 5 mm from the sheath peeling.
(1-2) The other reinforcing cord 21B has a second heat shrinkable tube 14 with an outer diameter of 3.5 mm cut to 30 mm, for example, and a third heat shrinkable tube 16 with an internal adhesive cut to 65 mm, for example. Put on. Similarly to the above, the sheath 6 having a length of, for example, 38 mm is peeled off at the distal end side, and the inner pipe 4 is cut at 5 mm from the sheath peeling.

(2-1) In a state where the fusion reinforcing sleeve 7 and the reinforcing tube 11 having an outer diameter of 2 mm are passed through one optical fiber in advance, the two optical fibers 3 and 3 are fusion spliced, and the fusion splicing fiber ( As shown in FIG. 5, the two optical fibers 3 and 3 that are fusion-spliced (referring to the entirety of the two optical fibers 3 and 3) are inserted into one reinforcing cord 21A. The fusion reinforcing sleeve 7 is placed on the fusion spliced portion of the two optical fibers 3 and 3.
In this embodiment, the two optical fibers to be fusion-spliced are a DSF fiber (dispersion shifted fiber) and an SM fiber (single mode fiber). In the description of FIG. 2, the two types of optical fibers are not particularly distinguished.
(2-2) Further, as shown in FIG. 6 (a), the fusion splicing fiber 3 is covered with the other reinforcing cord 21B, and there is a slight gap between the sheath ends of both the reinforcing cords 21A and 21B and both ends of the reinforcing tube 11. The gap c is set to an extent that can be formed. A detailed cross section in this state is shown in FIG. The optical fiber cord 1 (1A, 1B) is obtained by inserting the optical fiber 3 into the reinforcing cords 21A, 21B.
(2-3) Move and adjust the fiber 3 coming out from the opposite side so that the fusion reinforcing sleeve 7 comes to the center in the reinforcing tube 11, and connect the opposite fiber 3 and the reinforcing cord 21A. The optical fiber 3 is fixed by fastening with the tape 23 which is folded and bonded.
At this stage, the tensile strength fiber 5 on the one side of the reinforcing cord 21A (fiber cord 1A) is simply left in an extended state, but the tensile strength fiber 5 on the other side of the reinforcing cord 21B (optical fiber cord 1B) is illustrated. As described above, it may be folded back to the outer periphery of the reinforcing cord 21B and fixed with the tape 24.

(3-1) FIG. 7A is an enlarged view of the main part of FIG. From this state, when the first heat-shrinkable tube 13 is slid to the right in the drawing so as to come to the middle of the reinforcing tube 11, the tensile strength fiber 5 that has been scattered is automatically set as shown in FIG. Is attached to the outer periphery of the reinforcing tube 11 and is held in the first heat shrinkable tube 13.
At that time, since it is not necessary to specially treat the tensile strength fiber 5 and it may be in a state of being naturally extended, it is very easy to treat the tensile strength fiber 5 which is easily separated. Compared with this, workability is remarkably improved. Next, the first heat shrinkable tube 13 is heated and shrunk, for example, with a dryer.
(3-2) Next, the tape 24 is removed, and the direction of the tensile fiber 5 on the side of the other optical fiber cord 1B that has been folded back is forward (leftward in FIG. 7) as shown in FIG. Turn. There is no difficulty in the treatment of the tensile strength fiber 5 at that time. Next, when the second heat shrinkable tube 14 on the other side of the optical fiber cord 1B is slid to the left in the drawing so as to come on the first heat shrinkable tube 13 (in the middle of the reinforcing tube 11), FIG. As shown in FIG. 7 (d), the separated tensile strength fibers 5 are automatically attached to the outer periphery of the first heat shrinkable tube 13 and held in the second heat shrinkable tube 14. Similarly to the above, the treatment of the tensile strength fiber 5 at that time is extremely easy and the workability is good. Next, the second heat shrinkable tube 14 is heated to shrink.
When the heat-shrinkable tube 13 or 14 is heated and shrunk, the tip of the tensile strength fiber 5 is not hidden under the heat-shrinkable tube 13 or 14 (to be bonded later).

(4) Next, the adhesive 25 is applied to the portions of the tensile strength fiber 5 coming out from both sides of the heat-shrinkable tubes 13 and 14, and the tensile strength fiber 5 is bonded and fixed onto the reinforcing tube 11. In this case, the adhesive 25 is surely adhered to the reinforcing tube 11. At this time, if the tensile strength fibers 5 are bonded so as not to spread, finally the thickness of the reinforcing portion becomes constant and a good appearance is obtained.
FIG. 7E also shows the vicinity of the gap between the sheath ends 6a of the left and right optical fiber cords 1A and 1B and both ends of the reinforcing tube 11, that is, the portion where the tensile strength fibers 5 protrude from the sheath 6. In this way, the adhesive 25 'is applied so that the ends of the sheaths 6 of the optical fiber cords 1A and 1B and the ends of the reinforcing tube 11 are bonded and fixed, and at the same time, the tensile fibers 5 are bonded and fixed. At this time, care is taken so that the gap between the left and right reinforcing cords 21A and 21B and the reinforcing tube 11 does not spread too much.
Next, although illustration is omitted, the optical fiber cords 1A and 1B are pushed into the groove of the grooved sponge and fixed until the adhesive is dry.

(5-1) Next, the spiral tube 26 is wound from the position of 5 mm when the one reinforcing cord 21 </ b> A is peeled off to the position of 5 mm when the other reinforcing cord 21 </ b> B is peeled so that no gap is generated. 8 (a), the spiral tube 26 extends over the second heat shrinkable tube 14 from the sheath 6 portion of one optical fiber cord 1A to the sheath 6 portion of the other optical fiber cord 1B. Cover with.
The spiral tube 26 is wound using a slightly long spiral, but the spiral tube 26 is cut at the end of winding (FIG. 8 (A) shows the cut state). When the tensile strength fiber 5 is bonded and fixed with the previous adhesive 25, if the method of fixing the tensile strength fiber 5 is inadequate, the spiral tube 26 rises. Perform carefully.
(5-2) Next, the third heat-shrinkable tube 16 with the inner surface adhesive covering the other optical fiber cord 1B is slid leftward in FIG. , And cover the sheath 6 portion of one optical fiber cord 1A over the sheath 6 portion of the other optical fiber cord 1B.

(6-1) In the above-described operation, if the third heat shrinkable tube 16 is brought about 7 mm from the spiral tube 26, the third end with a width of about 7 mm at both ends (see FIG. 8B). The heat shrinkable tube 16 covers the sheath 6 of the optical fiber cord 1. In this state, the third heat shrinkable tube 16 is heated and shrunk from the middle.
(6-2) When the contraction of the third heat-shrinkable tube 16 is completed, the left and right optical fiber cords 1A and 1B are pushed into the groove 28a of the grooved sponge 28 and fixed as shown in FIG. Fix the tube 16 and the internal reinforcing tube 11 (the interior is not shown) so that they are straightened and cool. By contracting the contraction tube 16 from the middle, it is possible to eliminate the bias due to the contraction of the contraction tube 16.
Through the above steps, the fusion spliced portion reinforcing structure 30 of the optical fiber cord as shown in FIG. 1 is obtained.

In the above-described fusion splicing structure 30 for optical fiber cords, the tensile fibers 5 of the left and right optical fiber cords 1 are bonded and fixed on the outer peripheral surface of the reinforcing tube 11 so that the tensile fibers 5 are firmly fixed to each other. Detained. Further, since the third heat-shrinkable tube 16 is put over the sheath 6 portions of the left and right optical fiber cords 1, the sheaths 6 of the left and right optical fiber cords 1 are firmly held. Thus, since the tensile strength fibers 5 and the sheaths 6 of the left and right optical fiber cords 1 are firmly held, the fusion spliced portion of the optical fiber 3 is firmly reinforced.
In the above operation, the left and right tensile strength fibers 5 can be easily attached to the reinforcing tube 11 by sliding the first or second heat shrinkable tube 13 or 14, so that the tensile strength fibers 5 that are easily separated. This process is extremely easy and workability is good, and is extremely easy compared to the conventional method in which a reinforcing member is inserted into a protective pipe and an adhesive is filled.

  Further, according to the fusion splicing portion reinforcing structure 30 described above, the reinforcing member 8 used in the conventional structure described with reference to FIG. In addition, a die for manufacturing the reinforcing member is not necessary, and the cost can be greatly reduced. Also, the heat shrinkable tube (third heat shrinkable tube) 16 holds the sheaths 6 of the left and right optical fiber cords 1 and there is no need to fill the inside with an adhesive. The next step can be performed without waiting for the material to cure.

  Further, since the reinforcing tube 11 covers almost the entire length between the left and right sheath ends 6a and covers the optical fiber 3 exposed from the pipe 4, an adhesive 25 for bonding the tensile fibers 5 to each other is used as the optical fiber. There is no fear of adhering to 3. Note that the adhesive 25 ′ for bonding the reinforcing tube 11 to the optical fiber cord 1 is only at both ends of the reinforcing tube 11 and does not penetrate deeply into the reinforcing tube 11. There is no fear of adhesion. Therefore, unlike the conventional structure, there is no problem that anisotropy occurs in the curing shrinkage of the adhesive and nonuniform stress is generated in the optical fiber, which may break.

In the above-described embodiment, the procedure of inserting the fusion splicing fiber 3 in which the two optical fibers 3 and 3 are connected to the reinforcing cords 21A and 21B has been described. However, the present invention is not limited to such a case. The above-described fusion splicing portion reinforcing structure can be configured in the state of the optical fiber cord from the beginning (the state in which the optical fiber is put in the reinforcing cord). In this case, if the reinforcing cords 21A and 21B are slid with respect to the optical fiber 3, the same operation as described above can be performed.
Further, the present invention can be applied not only to an optical fiber cord in which an optical fiber is slidable as in the embodiment, but also to an optical fiber cord in which the optical fiber cannot slide in the optical fiber cord. In this case, the fusion bonding of the optical fibers is performed in a state where the fusion reinforcing sleeve 7 is covered in advance on the optical fiber of one optical fiber cord and the reinforcing tube 11 is covered on the reinforcing cord 21 portion. The reinforcing tube 11 used in this case has an inner diameter larger than the outer diameter of the reinforcing cord 21.

Although the above-mentioned embodiment is intended for the single-core optical fiber cord 1, it can also be applied to the case where the subject is a multi-fiber optical fiber cord. For example, an optical fiber cord 1 ′ shown in FIG. 11 has two optical fiber core wires (two core fibers) each having two optical fibers (0.25 mm UV strands) 3 ′ accommodated in a pipe 4 ′ having an oval cross section. A structure in which a tensile fiber 5 'such as an aramid fiber (Kevlar) is attached to the outer periphery of a loose tube core 2) and a sheath 6' such as PVC (vinyl chloride) is provided on the outside thereof.
In this case, basically, in FIGS. 1 to 9, instead of the circular cross-section pipe 4 containing one optical fiber 3, an oval cross-section pipe 4 ′ containing two optical fibers 3 ′ is used. What is necessary is just to assume the case where it uses.

Not in the embodiment of the present invention in FIG. 12 shows a reference example. In this reference example , the structure shown in FIG. 7E is housed in a protective pipe 31 made of ABS (acrylonitrile / butadiene / styrene copolymer) resin or vinyl chloride resin. In this case, the reinforcing member 32 is disposed in the protective pipe 31 and filled with the adhesive 33. The adhesive 33 may be the same as the adhesive 25 that bonds the tensile strength fibers 5 together.
In this case, it is disadvantageous in that the reinforcing member 32 is required as in the case shown in FIG. 13, but the adhesive 33 does not adhere to the optical fiber 3 accommodated in the reinforcing tube 11. There is an advantage that non-uniform stress due to the adverse effect of the adhesive does not occur in the optical fiber 3.

It is sectional drawing which shows the fusion splicing part reinforcement structure of the optical fiber cord of one Example of this invention, and is equivalent to the longitudinal cross-sectional view of the optical fiber cord connection part in FIG. It is the principal part perspective view which showed the inside of the fusion splicing part reinforcement structure of the optical fiber cord of FIG. 1 so that it might be easy to understand. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 illustrates an embodiment of a method for reinforcing a fusion spliced portion of an optical fiber cord according to the present invention, and is a diagram illustrating a reinforcing cord to be used; (A) is a plan view of two reinforcing cords; Is an enlarged cross-sectional view. It is a figure explaining the process following FIG. 3 of the fusion splicing part reinforcement method of an optical fiber cord. It is a figure explaining the process following FIG. 4 of the fusion splicing part reinforcement method of an optical fiber cord. FIGS. 6A and 6B are diagrams for explaining a process following FIG. 5 of the method for reinforcing the fusion spliced portion of the optical fiber cord, where FIG. 5A is a plan view and FIG. (A) is an enlarged view of the main part of FIG. 6, (b) to (e) are diagrams for explaining the four steps following (a), and (b), (c), (d), (e) It is done in order. It is a figure explaining two processes following FIG. 7 of the fusion splicing part reinforcement method of an optical fiber cord, and is performed in order of (A) and (B). It is a figure explaining the process following FIG. 8 of the fusion splicing part reinforcement method of an optical fiber cord. It is a figure common to this invention and a prior art example, and is sectional drawing of the optical fiber cord made into object by Example 1. FIG. It is a figure which shows the other example (Example 2) to which the present invention is applied, and is a cross-sectional view of a two-fiber optical fiber cord. It is sectional drawing which shows the fusion splicing part reinforcement structure of the optical fiber cord as a reference example . It is sectional drawing which showed the fusion splicing part reinforcement structure of the conventional optical fiber cord.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 1A, 1B, 1 'Optical fiber cord 2, 2' Optical fiber core wire 3, 3 'Optical fiber 4, 4' Pipe 5, 5 'Tensile fiber 6, 6' Sheath 7 Fusion reinforcement sleeve 11 Reinforcement tube 13 First heat shrink tube 14 Second heat shrink tube 16 Third heat shrink tube 21, 21A, 21B Reinforcement cord 23 Tape 24 Tape 25, 25 'Adhesive 26 Spiral tube 30 Fusion splicing of optical fiber cord Structure 31 Protective pipe 32 Reinforcing member 33 Adhesive

Claims (5)

Fusion splicing of the optical fiber cord for reinforcing a fusion splice of each other optical fiber cord which has been subjected to sheath the tensile strength fibers Sowase on the outside on the outer circumference of the loose tube type optical fiber housing the optical fiber in the pipe In the part reinforcement structure,
Cover the fusion splicing portion of the optical fibers exposed from the optical fiber cores of the optical fiber cords on both sides with a fusion reinforcing sleeve,
Covering the fusion reinforcing sleeve with a reinforcing tube in such a manner as to straddle the optical fiber core coating portion of one optical fiber cord from the optical fiber core coating portion of the other optical fiber cord,
Covering the first heat-shrinkable tube in a manner that does not hide the tip of the tensile strength fiber by interposing one tensile strength fiber on the outer periphery of the reinforcing tube,
A second heat-shrinkable tube by interposing the other tensile strength fibers to the outer periphery of the first heat-shrinkable tube to be brought in a manner that does not hide the distal end portion of the tensile strength fiber,
An optical fiber characterized in that both ends of the reinforcing tube, the left and right tensile strength fibers on the reinforcing tube, and the sheath end of the optical fiber cord are bonded and fixed to both sides of the first heat shrinkable tube and the second heat shrinkable tube. Reinforcement structure of the fusion splicing part of the cord.   A spiral tube is wound on the second heat-shrinkable tube so as to extend from the sheath portion of one optical fiber cord to the sheath portion of the other optical fiber cord, and then the second outermost layer is formed thereon. 3. The fusion spliced portion of an optical fiber cord according to claim 1, wherein the heat shrinkable tube of 3 is covered in such a manner as to extend from the sheath portion of one optical fiber cord to the sheath portion of the other optical fiber cord. Reinforced structure. 3. The fusion spliced portion reinforcing structure for an optical fiber cord according to claim 2, wherein the third heat shrinkable tube is a heat shrinkable tube with an adhesive having an inner surface coated with an adhesive. When reinforcing the fusion spliced portion of optical fiber cords in which a tensile fiber is added to the outer periphery of a loose tube type optical fiber core in which the optical fiber is housed in a pipe and a sheath is provided on the outer circumference, the fusion spliced portion is used. In the method of reinforcing the fusion spliced portion of the optical fiber cord for reinforcing
Cover the fusion spliced portion of the fibers exposed from the optical fiber cores of the optical fiber cords on both sides with a fusion reinforcing sleeve,
A reinforcing tube is placed on the fusion reinforcing sleeve in such a manner as to extend from the optical fiber core covering portion of one optical fiber cord to the optical fiber core covering portion of the other optical fiber cord. One of the tensile strength fibers is attached to the first, and then the first heat shrinkable tube that has been slidably covered on one of the optical fiber cords is slid to the fusion splicing side to reinforce the one tensile strength fiber from above. Cover the tube in a manner that does not hide the tip of the tensile strength fiber ,
Next, the other optical fiber cord side tensile fiber is attached to the outer periphery of the first heat shrinkable tube, and then the second heat shrinkable tube previously slidably covered on the other optical fiber cord is melted. It is allowed in a manner which does not hide the distal end portion of the tensile strength fiber to a first heat-shrinkable tube by sliding the destination connection portion side from the top of the other tensile strength fiber,
Wherein at both sides of the first heat-shrinkable tubing and the second heat-shrinkable tubing, optical fibers, characterized in that bonding and fixing the sheath end across the tensile strength fiber and the optical fiber cord of the left and right on the reinforcing tube on the reinforcing tube How to reinforce the fusion splice of a cord. After covering the second heat-shrinkable tube, the spiral tube is wound on the second heat-shrinkable tube so as to extend from the sheath portion of one optical fiber cord to the sheath portion of the other optical fiber cord. , then a third heat-shrinkable tube as the outermost layer, light according to claim 4, wherein the covering in straddling manner on the sheath portion of the other optical fiber cord from the sheath portion of one of the optical fiber cord A method for reinforcing a fusion spliced portion of a fiber cord.

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