JP2005077766A - Reinforcing structure of fusion splicing part of optical fiber cord and reinforcing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a reinforcing structure of a fusion splicing part which has an excellent appearance regardless of its internal form and is bendable. <P>SOLUTION: A spiral tube 26 is wound around the fusion splicing part of optical fiber cords 1 so as to straddle from the sheath part 6 of an optical fiber cord 1A to the sheath part 6 of the other optical fiber cord 1B. An example given in the figure shows that a fusion splicing and reinforcing sleeve is overlaid on the fusion splicing part and further a reinforcing tube is overlaid thereon; the tension fibers of the right and the left optical fiber cords are bonded to each other and fixed along the outer periphery of the reinforcing tube with the heat shrinkable tubes 13 and 14; a spiral tube 26 is overlaid while being wound on the heat shrinkable tubes by winding; and further a heat shrinkable tube 16 is overlaid thereon. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a fusion splicing portion reinforcing structure and a reinforcing method for optical fiber cords that reinforce fusion splicing portions of optical fiber cords.

  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.

  When reinforcing the fusion splicing portion of the optical fiber cord, for example, as shown in FIG. 15, the fusion splicing sleeve 7 is put on the fusion splicing portion between the optical fibers 3, and the left and right optical fiber cords 1 (one light Tensile fibers 5 and 5 of a fiber cord 1A and the other optical fiber cord 1B are overlapped on a fusion reinforcing sleeve 7, and a rod-like reinforcing member 8 is elongated in the vicinity of the fusion reinforcing sleeve 7. A method in which the protective pipe 9 is placed along the direction and a protective pipe made of ABS resin, vinyl chloride resin or the like is placed thereon and the adhesive 10 is filled in the protective pipe 9 is widely used. 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.

  In the conventional fusion splicing portion reinforcing structure, since a hard member is generally used as the reinforcing member 8 and the protective pipe 9, it cannot be bent, and the layout in the optical device is restricted or the work such as wiring is difficult. There is a case. Moreover, when a soft member is used as the protective pipe 9, the internal shape appears, and the appearance quality deteriorates. Further, a reinforcing structure that does not use the rod-like reinforcing member 8 is also conceivable, but in this case, if a hard member is used as the protective pipe 9, it cannot be bent as described above. Further, when the soft protective pipe 9 is used after the internal structure that can ensure the reinforcement of the fusion splicing portion is used, there is a problem that the internal shape comes out and the appearance quality is deteriorated.

  The present invention has been made to eliminate the above-described conventional drawbacks. Even when the interior to be reinforced is irregular, it is possible to form a reinforcing portion having a good appearance regardless of its shape, and bend to some extent. It is possible to improve workability.

  According to a first aspect of the present invention, there is provided an optical fiber cord fusion splicing portion reinforcing structure, wherein a spiral tube is connected to a fusion splicing portion between optical fiber cords from a sheath portion of one optical fiber cord to the other light. It is characterized by being wrapped and covered in a manner straddling the sheath portion of the fiber cord.

A second aspect of the present invention relates to the first aspect of the present invention, wherein the heat-shrinkable tube is straddled on the spiral tube that covers the fusion spliced portion of the optical fiber cord from the sheath portion of one optical fiber cord to the sheath portion of the other optical fiber cord. It is characterized by being covered in a rugged manner.

A third aspect is characterized in that, in the first or second aspect, the heat-shrinkable tube is a heat-shrinkable tube with an adhesive having an inner surface coated with an adhesive.

According to a fourth aspect of the present invention, there is provided a method for reinforcing a fusion spliced portion of an optical fiber cord, wherein a spiral tube is connected to a fusion spliced portion of optical fiber cords from a sheath portion of one optical fiber cord to a sheath portion of the other optical fiber cord. It is characterized in that it is wound and covered in a manner that straddles.

According to the present invention, since the fusion spliced portion of the optical fiber cord is reinforced with the spiral tube, even if the internal structure to be reinforced is irregular, it is possible to form a reinforcing portion having a good appearance regardless of its shape. it can.
Further, since the reinforcing portion by the spiral tube can be bent, there is little restriction on the layout in the optical device, and workability of work such as wiring can be improved.
When the heat shrinkable tube is placed on the spiral tube as in claim 2, the spiral tube that can be shrunk can effectively transmit the gripping force of the heat shrinkable tube to the inside. The force is effectively utilized and a sufficiently reinforced fusion splice is formed.
When a heat-shrinkable tube with an adhesive is used as in claim 3, the connection between both ends of the heat-shrinkable tube and the sheath portion of the optical fiber cord is ensured sufficiently, and the fusion splicing portion is further reinforced. It will be certain.

  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. In this embodiment, as will be described later, the reinforcing tube 11 is used. 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) is attached to the outside thereof. (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.

In the present invention, the spiral tube 26 is used. In this embodiment, the spiral tube 26 is wound on the second heat shrinkable tube 14 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. ing. Then, the third heat shrinkable tube 16 having an adhesive applied to the inner surface, for example, as the outermost layer is straddled from the sheath 6 portion of one optical fiber cord 1A to the sheath 6 portion of the other optical fiber cord 1B. It is covered in such a manner.
The spiral tube is made of polyethylene, nylon, or a plastic such as fluororesin, and is a flexible component such as a spiral band formed by extrusion, for example, and the spiral band is wide, and will be described later with reference to FIG. ) Is a member that can be wound around the linear member 50 or the like and covered with the wire member 50, for example, as shown in a perspective view in FIG. In addition, since the diameter can be expanded and contracted, and the spiral band is wide, it can be pressed with sufficient force when reducing the diameter, so when wound around a thicker one, the inner periphery Contact the surface without any gaps.

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 such an extent that it 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, it is not necessary to perform any special treatment on the tensile strength fiber 5, and it may be in a state where the tensile strength fiber 5 is simply extended naturally. It is extremely easy and the workability is remarkably improved as compared with the conventional work that is simply performed by hand. 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 and covered. That is, 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. The mode of the spiral tube 26 when winding is as shown in FIG. Thus, as shown in FIG. 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 in a rugged manner.
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.

Since the above-described optical fiber cord fusion splicing portion reinforcing structure 30 is reinforced by covering the spiral tube 26, a reinforcing portion having a good appearance can be formed regardless of the internal shape. In particular, when the first and second heat shrinkable tubes 13 and 14 are provided inside as in the embodiment, if the outermost heat shrinkable tube 16 is directly covered on the first and second heat shrinkable tubes 16 and 14, the internal irregularities appear. Since the tube 26 covers the heat shrinkable tubes 13 and 14 and has a smooth outer shape, when the outermost heat shrinkable tube 16 is further covered thereon, the appearance quality is sufficiently good.
In addition, unlike the case of using a hard member, the reinforcing portion by the spiral tube 26 can be bent, so that there are few restrictions on the layout in the optical device, and the workability of the work such as wiring is improved. be able to.
Further, since the spiral tube 26 can be shrunk, the gripping force of the outermost layer heat-shrinkable tube 16 can be effectively transmitted to the inside by being in close contact with the inside, and therefore the gripping force of the outermost layer heat-shrinkable tube 16 is reduced. A fusion spliced portion which is effectively utilized and sufficiently reinforced is formed.
Moreover, since the outermost layer heat shrinkable tube 16 has an inner surface adhesive, it is possible to secure a sufficiently good connection between the ends of the heat shrinkable tube 16 and the sheath 6 portion of the optical fiber cord 1 and to more reliably reinforce the fusion spliced portion. It will be something.

Further, in the case of this embodiment, the tensile strength 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 strength fibers 5 are firmly fixed to each other. . Further, since the third heat-shrinkable tube 16 is placed 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 case where 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, there is no inconvenience when the adhesive adheres to the optical fiber.

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.

The fusion splice structure of the optical fiber cord using the spiral tube 26 is not limited to the above-described embodiment, and the tensile strength fiber 5 is fixed on the reinforcing tube 11 with an adhesive as shown in FIG. The spiral tube 26 is directly formed on the spiral tube 26 (same as the case where the first and second heat-shrinkable tubes 13 and 14 are not shown in FIG. 7E, although the tensile strength fiber 5 is not shown in FIG. 11 (A)). It is also possible to cover it.
Further, as shown in FIG. 11 (b), it is also conceivable that the outermost heat shrinkable tube 16 is covered on the reinforcing tube 11 of FIG. 11 (a).
Further, as shown in FIG. 11C, it is also conceivable that a rod-shaped reinforcing member 41 is attached to the reinforcing tube 11 and the spiral tube 26 is entirely covered from above.

Further, as shown in FIG. 12, a rod-shaped reinforcing member 42 is attached to the structure of FIG. 11A (the reinforcing tube 11 is covered with the spiral tube 26) and accommodated in the protective pipe 43, and the inside It is also conceivable to have a structure filled with adhesive 44.

Furthermore, since the inside of the spiral tube 26 is not particularly limited, it is not limited to the case where the reinforcing tube 11 is used as in the above-described embodiments. FIG. 13 illustrates this. That is, left and right tensile strength fibers 5 (not shown in FIG. 13) are attached to each other from the left and right on a fusion reinforcing sleeve 7 placed on a fusion splicing portion of an optical fiber, and a spiral tube 26 is placed thereon. It is also conceivable that the structure is wound and covered. In the illustrated example, the outermost heat shrinkable tube 16 is covered.

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. 14 includes 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 each of the embodiments shown in FIGS. 1 to 13, instead of the circular cross-section pipe 4 containing one optical fiber 3, the oval cross-section containing two optical fibers 3 ′ is used. What is necessary is just to assume the case where pipe 4 'is used.

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 fusion splicing part in FIG. FIG. 2 is a partial perspective view showing the inside of the fusion splicing portion reinforcing structure of the optical fiber cord of FIG. 1 for easy understanding. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram illustrating a preparation stage of an embodiment of a method for reinforcing a fusion spliced portion of an optical fiber cord according to the present invention, showing a reinforcing cord to be used, and (a) is a plan view of two reinforcing cords. (B) is an enlarged sectional view. It is a figure explaining the process following FIG. 3 of the preparation stage of the fusion splicing part reinforcement method of an optical fiber cord. It is a figure explaining the process following FIG. 4 of the preparation stage of the fusion splicing part reinforcement method of an optical fiber cord. FIGS. 6A and 6B are diagrams illustrating a process following FIG. 5 in a preparation stage of a method for reinforcing an optical fiber cord fusion splicing portion, 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 four steps in the preparation stage following (a), and (b), (c), (d), ( E) It is performed in the order. The characteristic part of the fusion splicing part reinforcement method of the optical fiber cord of the present invention will be described. FIG. 7 is a diagram for explaining two steps following FIG. 7, and is performed in the order of (a) and (b). (C) is a perspective view for explaining the structure of the spiral tube. 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. (A), (b), and (c) are diagrams showing other embodiments of the fusion splicing portion reinforcing structure of the optical fiber cord of the present invention. It is a figure which shows the further another Example of the fusion splicing part reinforcement structure of the optical fiber cord of this invention. It is a figure which shows the further another Example of the fusion splicing part reinforcement structure of the optical fiber cord of this invention. It is a figure which shows the other example (Example 3) to which this invention is applied, and is sectional drawing of a two-core optical fiber cord. It is the longitudinal cross-sectional view 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 Adhesives 41 and 42 Bar-shaped reinforcing member 43 Protective pipe 44 Adhesive

Claims (4)

  An optical fiber cord, characterized in that a spiral tube is wound around a fusion splicing portion between optical fiber cords 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. Fusion splicing part reinforcement structure.   The heat-shrinkable tube is covered on the spiral tube covered by the fusion spliced portion of the optical fiber cord 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. The fusion splicing portion reinforcing structure for an optical fiber cord according to claim 1.   3. The fusion-bonding portion reinforcing structure for an optical fiber cord according to claim 1, wherein the heat-shrinkable tube is a heat-shrinkable tube with an adhesive having an inner surface coated with an adhesive. An optical fiber cord characterized in that a spiral tube is wound and covered on a fusion spliced portion between optical fiber cords 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. Fusion splicing reinforcement method.

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