JPS62178910A - Connecting joint for multicore optical fiber cable - Google Patents

Abstract

PURPOSE:To reduce a welding joint to the same degree as the outside diameter as a connecting cable, and also to make it excellent in its workability and joint reliability, by containing an uncovered line of an optical fiber, which has been generated by following a welding work, in a grooved spacer which can be attached and detached to and from the outside periphery of an inside fixed cylinder of a split type. CONSTITUTION:Multicore optical fiber cables 22 which have been opposed to each other are melted and coupled by peeling off covering of a protective sheath and laying bare an optical fiber 3 in order to execute fusion welding of the optical fiber 3, and by a discharge arc heat of an arc welding machine in a state that the respective end faces have been butted. Subsequently, a tension member 4 is joined to each other by an expansion joint 18, and an inside fixed cylinder 10 of a split type to which a grooved spacer 19 has been installed is inserted between the optical fiber 3 and the tension member 4. Each optical fiber 3 is selected in advance in accordance with its deflection quantity, and inserted into a containing groove of the prescribed grooved spacer 19 which has been installed to he inside fixed cylinder 10. When all the optical fibers 3 have been inserted completely into the groove of the inside fixed cylinder 10, its periphery is protected by winding a glass tape 8, and in the end, a protective sleeve 9 having a heat contractibility is installed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a connection joint suitable for a fusion splice section of an optical fiber cable.

[Background of the invention]

A conventional fusion splicer of a multicore optical fiber cable will be explained below with reference to FIGS. 5, 6, and 7. First of all, the fifth
The figure shows the configuration of a multicore optical fiber cable. A multicore optical fiber cable consists of a tension member 4 that provides mechanical strength by interweaving a plurality of steel wires, a spacer 2 surrounding this, and an optical fiber 3 that is housed and protected in a plurality of grooves provided on the outer periphery of the spacer 2. and a sheath 1 etc. that protects the whole.

The individual grooves provided on the outer periphery of the spacer 2 have a helical structure, and the optical fibers 3 are also arranged helically within each groove.

FIG. 6 shows how multi-core optical fiber cables are fusion spliced. In order to fusion weld the optical fiber 3, it is necessary to peel off the protective sheath 1 and expose the optical fiber 3. The exposed optical fibers 3 are fused and bonded by the discharge arc heat of the arc welding machine 6 with their respective end faces butted against each other. In addition, the tension member 4 is
Although it is possible to join by fusion welding or mechanical methods, mechanical joining by caulking is generally advantageous. optical fiber 3
In order to fuse the optical fibers 3 to A common method is to fully expose the protective sheath 1, match the end faces, and then fuse them using the heat of arc discharge. As a result, once the optical fiber 3 has been exposed, it is impossible to restore it to its original state, and after completion of the bonding, it is necessary to bend it with as little curvature as possible and store it in order to save space. However, if it is bent with a small curvature, the loss due to the refraction of light increases, so a specific radius of curvature must be ensured. Therefore, if the radius of curvature is increased and the wire is wound, the diameter of the joint portion will be increased because it will be wound along the outer periphery of a large cylinder.

On the other hand, the exposed length of the tension member 4 is shorter than the exposed length of the optical fiber 3. This is optical fiber 3
This is because the tension member 4 is wound in a spiral, whereas the tension member 4 extends in a straight line. In other words, there is no problem with the tension member 4 in terms of the shape of the joint. What is important is to minimize the deflection of the optical fiber 3 after welding and improve joint performance, but even if the tension member 4 is shortened, the amount of deflection of the optical fiber 3 will not be reduced.

FIG. 7 shows an example in which multicore optical fiber cables are connected together and then reinforced by molding with a plastic tube containing glass fiber. The structure of the joint is complex and the width is much larger than the outer diameter of the cable to be connected. This is because, as mentioned earlier, the optical fiber 3 that has been welded has been bent greatly, so the optical fiber 3 is exposed while making the surface of the split (split) 10 spirally on the internal fixed tube within a range that does not cause extreme bending. The wire is absorbed, a glass tape 8 is wrapped over the wire, and the outermost portion is further covered with a protective sleeve 9. The installed cable and connection joint are fixed via a cable clamp 11, a protective metal fitting 12, and an internal fixing tube 10. The ends are completely sealed with waterproof tape 13 and self-fusing tape 15 for waterproofing. Furthermore, the heat-shrinkable sleeves 14 and 16 firmly integrate the connecting joint and the cable to be connected.

The conventional connection joint made of the above parts is approximately 20φ.
When connecting multi-core optical fiber cables, the length of the joint is about 1m and the outermost diameter is about 130φ, which is not only a very large joint shape compared to the size of the cable to be connected, but also difficult to work with. The reliability of the joint is also a concern.

In addition, in the conventional connection joint structure, protrusions may occur depending on the location where the cable is laid, impeding workability and passage, and even making high-density mounting impossible. Against this background, there has been a desire to develop a connection joint that reduces the fusion splicing part of a multicore optical fiber cable to the outer diameter of the cable to be connected, and is highly reliable and easy to work with.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a multi-core optical fiber cable connection joint and connection method that reduces the fusion splicing portion of a multi-core optical fiber cable to the outer diameter of the cable to be connected and has excellent workability and joint reliability. .

[Summary of the invention]

The present invention solves the problem that the connecting part of a conventional multi-core optical fiber cable is abnormally large compared to the diameter of the cable to be connected, and that the connecting part has an abnormally long structure of about 1 m. As a means of reducing the length of the connected cable to the outer diameter of the connected cable and reducing the length of the connection part as much as possible, we focused on spacers used to protect expansion joints and multi-core optical fiber cables, and developed The stripped optical fibers and wires generated during the process are housed in a removable grooved spacer on the outer periphery of the split-type internally fixed tube, while the length of the joint is adjusted using an expandable strength member, thereby solving the aforementioned problem. solved.

As shown in FIG. 7, the structure of a conventional cable connection section reinforced by molding with a glass fiber-filled plastic tube is such that the exposed optical fiber 3 is attached to the outer periphery of an internal fixing tube 10 that is larger than the outer diameter of the cable to be connected. By forcing the government to do so, they were able to become entrenched. The present invention utilizes a strength member with an expandable and contracting function to obtain a connection part with the outer diameter value of the cable to be connected, and a detachable member having a linear groove or a meandering groove that can absorb the deflection of the optical fiber in advance. By preparing and using several types of spacers, the connection work can be standardized, so this method has excellent workability and joint reliability.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIGS. 1, 2, 3, and 4. FIG. 1 shows an overall outline of the invention. FIG. 2 schematically shows an expansion joint 18 that connects the tension member 4 that provides mechanical strength. Fig. 3 is an explanatory diagram of a grooved spacer, and Fig. 4 shows a removable grooved spacer and a split-type internal fixed cylinder.

First, in FIG. 1, the multi-core optical fiber cable connection joint of the present invention has a part that provides mechanical strength consisting of a tension member 4 and a connection body of an expansion joint 18 that connects the tension member 4, and a grooved part that houses the optical fiber 3. It is composed of three large parts: the spacer 19, the inner fixing tube 10, and the protective sleeve 9 made of a heat-shrinkable tube that protects the entirety.

Next, the steps until the multi-core optical fiber cable connection joint of the present invention is installed will be explained step by step.

First, the protective sheath 1 of the multi-core optical fiber cables 22 facing each other is peeled off to expose the optical fiber 3 for fusion welding of the optical fiber 3.

The exposed optical fibers 3 are fused and bonded by the discharge arc heat of the arc welding machine 6 with their respective end faces butted together. The tension member 4 is then joined to the shingle with an expansion joint 18. The tension member 4 and expansion joint 18' will be explained with reference to FIG.

The expansion joint 18 is composed of a tension member 4, a joint 24 that is crimped by a crimping device (not shown), and an outer cylinder 23 that holds the joint, and each rotatably moves left and right via threads. For this reason, the length can be adjusted at both ends of the tension member 4. tension member 4
Once the distance between them is determined, caulk the joint 24.

After the fusion welding of the optical fiber 3 and the caulking of the tension member 4 are completed, a split internal fixing tube 10 equipped with a grooved spacer 19 is inserted between the optical fiber j and the tension member 4. Each optical fiber 3 is selected in advance according to its amount of deflection, and inserted into a storage groove of a predetermined grooved spacer 19 attached to the internal fixed cylinder 10. After all the optical fibers 3 have been inserted into the grooves of the internal fixing cylinder 19, a glass tape 8 is wrapped around them to protect them. By wrapping the glass tape 8, the optical fibers accommodated in the grooves of the grooved spacer 19 are completely fixed. Finally, a protective sleeve 9 made of a heat-shrinkable tube is attached to complete the work. In the above explanation, the work progresses easily within a range where the error in the length of the tension member 4 and the optical fiber 3 after connection is small. This corresponds to case (1) shown in FIG.

However, in actual fusion welding of the optical fibers 3, there is a concern that errors are likely to occur in the connection length. Therefore, in the present invention, although the length is adjusted using the expansion joint 18, the case is taken into consideration where the optical fiber still has a large degree of deflection. In other words, in cases (2) and (3) in Figure 3, expansion joint 1
When the length of the adjustable connection part in 8 is L, this represents the treatment method when the welded optical fiber becomes extremely long.In such a case, use a meandering grooved spacer and store it in the required groove. It shows what you should do.

FIG. 4 shows a state in which the removable split type grooved spacer 19 of the present invention is attached to the internal fixed cylinder 10. As shown in FIG. The grooved spacer 19 attached to the internal fixed cylinder 10 has a meandering groove that can absorb the amount of deflection to the joint length that occurs during fusion welding of the optical fiber 3. If spacers 27, 28, 29, etc. are prepared in advance, connection errors ranging from large to small can be effectively absorbed.

〔Effect of the invention〕

According to the present invention, it is possible to eliminate the joint structure that is larger than the outer diameter of the cable to be connected, which has conventionally been seen in the fusion splicing part of multi-core optical fiber cables, improving cable installation workability, securing passage space, and improving the efficiency of multi-core optical fiber cables. This has the effect of improving joint performance.

[Brief explanation of drawings]

1 is a configuration diagram of a multi-core optical fiber cable connection joint of the present invention, FIG. 2 is a sectional view of an expansion joint of the present invention, FIG. 3 is an explanatory diagram showing an example of deflection of an optical fiber connection part, and FIG.
The figures are an explanatory diagram of a split-type grooved spacer that can be attached to and detached from the internal fixed tube of the present invention, Figure 5 is a structural diagram of a multi-core optical fiber cable, Figure 6 is a schematic diagram of the connection operation of a multi-core optical fiber cable, and Figure 7 The figure is a configuration diagram of a conventional multi-core optical fiber cable connection joint. DESCRIPTION OF SYMBOLS 1... Protective sheath, 2... Spacer, 3... Optical fiber, 7... Optical fiber joint part, 8... Glass tape, 9... Protective sleeve, 10... Internal fixed cylinder, 11... Cable clamp, 12... Protective metal fittings, 13... Waterproof tape.

Claims (1)

[Claims] 1. At the fusion splicing part of a multi-core optical fiber cable, which consists of a tension member responsible for mechanical strength, a spacer surrounding it, an optical fiber housed in a groove provided in the spacer, and a sheath that covers all of these, an internal fixed cylinder and A connection joint characterized by using a removable split-type grooved spacer on its outer periphery.