JPS6153687B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a member for reinforcing an optical fiber core connection section, which is composed of a heat-shrinkable tube and a hot-melt adhesive tube.

As is well known, optical fiber wires have characteristics such as being lighter and smaller in diameter than conventional metal transmission lines, and are highly flexible, but because they are made of glass, they are easily scratched and prone to breakage. Therefore, it cannot be used as is for a transmission line.

For this reason, conventionally, as shown in FIG. 1, a cored optical fiber 3 is generally used in which a coating 2 is formed on the outer periphery of an optical fiber 1 using polyamide resin (commonly known as nylon) or the like.

When connecting such optical fiber core wires, the optical fibers are fusion spliced after the coating is removed, and then the fusion splice and the coating layers at both ends of the spliced portion are integrated to form a fusion splice. It is common practice to form a reinforcing part to protect the wear part.

FIG. 2 shows a reinforcing member using a heat shrink tube as one of the reinforcing members conventionally used. This has a structure in which a hot-melt adhesive tube 4 having an inner diameter larger than the outer diameter of the optical fiber core coating and a reinforcing stainless steel rod 5 are inserted into a heat-shrinkable tube 6. The reinforcing method using this member is as described below. First, the core wire is passed through a hot melt adhesive tube before fusion splicing, and after fusion splicing, as shown in Figure 3. Then, the reinforcing member is shifted so as to straddle the wire fusion splicing portion 7 and the covering portions 2 at both ends, and further heated to shrink the heat-shrinkable tube.
The internal adhesive secures and reinforces the connection.

By the way, in this case, since there is a large difference between the inner diameter of the hot-melt adhesive tube and the outer diameter of the optical fiber core, the reinforcing member may move freely along the core during fusion splicing work. have Particularly when the work site is inside a manhole or on a utility pole, dust and dirt often adhere to the optical fiber core during connection work.As a result of the reinforcing member moving, dust and dirt may adhere to the inner surface of the adhesive tube. This has the drawback that the fused wires may absorb dirt and dirt, leading to breakage of the fused wires during or after reinforcement.

However, simply the inner diameter of the adhesive tube and
This problem can be solved to some extent by reducing the difference between the outer diameters of the optical fibers, but on the other hand, it is difficult to pass the fibers through, and in the worst case scenario, the fibers may get caught in the sheathing when returning to the fusion zone. However, there was a drawback that the fused portion broke.

The present invention has been made in view of the above points, and includes a heat-melt adhesive tube having an inner diameter larger than the outer diameter of the coated part of the optical fiber core, which is inserted into a heat-shrinkable tube, One or both ends of the adhesive tube are characterized by shrinking to a diameter that is approximately the same as the outer diameter of the optical fiber core coating, and its purpose is to provide reinforcement during fusion splicing of core wires. An optical fiber core connection that prevents members from moving freely, prevents dust and dirt from being introduced into the adhesive tube, and does not affect the insertion of core wires or the movement of reinforcing members. The object of the present invention is to provide a reinforcing member for the parts.

The drawings will be explained in detail below. That is,
FIG. 4 is a sectional view showing an embodiment of the present invention, in which the inner diameter of one end of the heat-shrinkable tube 16 and the hot-melt adhesive tube 14 inserted therein is equal to that of the optical fiber core wire 13. It is shrunk until it becomes approximately equal to the outer diameter of the coating, and the weight of the entire reinforcing member is supported by the frictional force between the coating of the inserted optical fiber core wire 13 and the adhesive tube 14. Further, the stainless steel rod 15 inside the heat shrink tube 16 has a diameter that prevents it from sliding out from inside the heat shrink tube 16. Note that a reinforcing rod such as the stainless steel rod 15 is not necessarily required.
Once the core wire is inserted and the reinforcing member is positioned, it will not be affected by vibration or tilt and will not move from its initial position. There is no need to worry about importing. The core wire is inserted through the narrow opening before the welding operation begins, but at that point the core wire is coated to the extreme end, so the fiber is not damaged and the insertion operation is easy. When the fusion of the core wires is completed, the entire reinforcing member is shifted so as to cover the fusion spliced portion 17 of the strands and the core wire coatings at both ends, and then heated from the outside to seal the internal hot-melt adhesive tube. The heat shrink tube 16 is shrunk together with the heat shrink tube 14 to complete the reinforcement.

FIG. 5 is a sectional view showing another embodiment of the present invention before reinforcement is completed, in which one opening of a hot-melt adhesive tube 14', which is longer than the heat-shrinkable tube 16, is projected in a funnel shape. Then, the heat-shrinkable tube 16 immediately after that is shrunk so that the inner diameter of the heat-melt adhesive tube 14 inside it becomes the optical fiber core wire 13.
The outer diameter of the coating is approximately the same as that of the outer diameter of the coating. The effect of the frictional force between the reinforcing member and the optical fiber core, the reinforcing method, and the necessity of the reinforcing rod are the same as in the embodiment shown in FIG. 4, it is easier to insert the tube into the hot-melt adhesive tube than in the case shown in FIG.

FIG. 6 is a cross-sectional view of another embodiment of the present invention before completion of reinforcement, in which a heat-shrinkable tube 16' that is longer than the heat-shrinkable tube 16' that is shrunk to the same extent as the outer diameter of the core wire at both ends of the reinforcing member is shown. Melt adhesive tube 1
Both openings of 4' are projected in a funnel shape, and the heat shrink tube 16' immediately behind them is shrunk.
The inner diameter of the hot-melt adhesive tube 14'' therein is approximately equal to the outer diameter of the coating of the optical fiber core wire 13. According to this, the friction between the reinforcing member and the optical fiber is reduced. The effect of the force, the reinforcing method, and the need for reinforcing rods are the same as in the embodiments shown in FIGS. Workability is good because it is easy to insert the core wire even from the inside.Also, since both ends of the reinforcing member are in close contact with the optical fiber core, the possibility of introducing dust and dirt is less than in the previous embodiment. Become.

FIG. 7 is a cross-sectional view of another embodiment of the present invention immediately before reinforcement, in which one opening of a hot-melt adhesive tube 14', which is longer than the heat-shrinkable tube 16, is protruded in the shape of a funnel. Then, the heat-shrinkable tube 16 immediately after that is shrunk, and the inner diameter of the internal hot-melt adhesive tube 14' becomes the optical fiber core wire 13.
In this case, it can be easily moved on the optical fiber core wire 13, but in a stationary state, the cushion material 18, which has excellent adhesion, is thermally melted. It is glued into the funnel-shaped protruding opening of the adhesive tube 14'. According to this, the effect of friction between the reinforcing member and the optical fiber, the reinforcing method, and the necessity of the reinforcing rod are the same as in the embodiments shown in FIGS. 4, 5, and 6, but the cushion Since the material 18 is provided, when the optical fiber core wire 13 is inserted, it is possible to wipe off dust, dirt, etc. from the surface of the core wire and prevent them from entering the inside of the hot-melt adhesive tube 14. It has advantages.

By the way, a point common to the above four embodiments is that the hot melt adhesive tubes 14, 14', 1
In order to shrink the inner diameter of the end face of the optical fiber 13 to a diameter that is almost the same as the outer diameter of the optical fiber 13, for example, in order to shrink the inner diameter of the end face of the optical fiber 13 to a diameter that is almost the same as the outer diameter of the optical fiber 13, for example, a material with the same outer diameter as the optical fiber 13 is placed inside the hot-melt adhesive tube 14, 14', 14''. After inserting the jig, the heat-shrinkable tubes 16, 16' are heated and shrunk. This shrinking process is performed using hot melt adhesive tube 1.
4, 14', 14'' melting point is heat shrink tube 16,
This is possible because it is lower than the contraction start temperature of 16'.

In each of the embodiments shown in FIGS. 4 to 7, it is not necessary that the ends of the heat-shrinkable tubes 16, 16' be shrunk, but as is clear from the above description, the heat-shrinkable tubes 16, 16' It is more convenient to work and to hold the hot melt adhesive tubes 14, 14', 14'' if the ends of the tubes are constricted.

FIG. 8 is a cross-sectional view showing the reinforcing part of the optical fiber core fusion splicing part using the reinforcing member of FIG.
Although it protrudes from the optical fiber core 13, it is sufficiently adhered to the periphery of the fusion spliced portion 17 of the optical fiber core wire 13, reinforcing this portion. Note that the reinforcing stainless steel rod 15 is not necessarily required.

FIG. 9 is a cross-sectional view showing a reinforcing member in storage as another embodiment of the present invention, and this reinforcing member has only one end shrunk, as shown in the figure. A clean stepped round rod 19 having an outer diameter substantially the same as the optical fiber core wire and one end having an outer diameter substantially the same as the inner diameter of the hot-melt adhesive tube 14' is inserted into the reinforcing member. As a result, the adhesive tube 1 is removed from the outside during storage (including during transportation, etc.).
It is possible to prevent dust and dirt from entering the inside of the housing 4'.

FIG. 10 is a sectional view showing a reinforcing member in storage as another embodiment of the present invention, and this reinforcing member has both ends contracted, and as shown in the figure, an optical fiber A clean round rod 20 having an outer diameter approximately the same as the outer diameter of the core wire is inserted into the reinforcing member. The effect is the same as that in FIG. 9, and the inner surface of the adhesive tube 14'' can be kept clean even during storage.

As explained above, a heat-melt adhesive tube having an inner diameter larger than the outer diameter of the coated part of the optical fiber is inserted into the heat-shrink tube, and one end of the heat-shrink tube and the heat-melt adhesive tube is inserted into the heat-shrink tube. Since the core or both ends of the optical fiber have been shrunk to an inner diameter that is almost the same as the outer diameter of the coated part of the optical fiber, after inserting the optical fiber into the reinforcing member, there is a Since the reinforcing member does not move arbitrarily due to frictional force, it has the advantage of being easy to handle during reinforcing work. In addition, since the reinforcing member does not move around along the core wire, it has the advantage that dust, dirt, etc. adhering to the surface of the core wire are not introduced into the hot-melt adhesive tube, improving reliability after reinforcement. be. Further, if one or both ends of the hot-melt adhesive tube are processed into a funnel shape, there is an advantage that the optical fiber core can be easily inserted. In addition, when storing the reinforcing member of the present invention, it is recommended to use a clean round rod having an outer diameter that is approximately the same as the optical fiber core wire, or one of which has an outer diameter that is approximately the same as the optical fiber core wire. By inserting a clean stepped round rod, one end of which has an outer diameter that is approximately the same as the inner diameter of the hot-melt adhesive tube, into this reinforcing member, the inner surface of the adhesive tube can be kept clean. be.

Although the present invention is composed of a heat-shrink tube and a heat-melt adhesive tube, the same effects as the present invention can be expected even if the heat-melt adhesive tube of the present invention is used alone. . However, in this case, it is necessary to sufficiently bond the adhesive and the optical fiber fusion spliced portion by some method.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing an optical fiber core wire, Fig. 2 is a block diagram showing a reinforcing member using a conventional heat shrink tube, and Fig. 3 is a block diagram showing a reinforcing member using a conventional heat shrink tube. FIG. 4 is a cross-sectional view showing one embodiment of the present invention, FIG. 5 is a cross-sectional view showing another embodiment of the present invention, and FIG. FIG. 7 is a cross-sectional view showing another embodiment of the present invention, FIG. 8 is a fusion spliced optical fiber using the reinforcing member shown in FIG. 6. 9 and 10 are cross-sectional views illustrating the storage state of the reinforcing member according to the present invention. 13... Optical fiber core wire, 14, 14', 14''...
Hot-melt adhesive tube, 15...stainless steel rod,
16, 16'... Heat shrink tube, 17... Optical fiber core fusion splicing part, 18... Cushion material, 19...
Stepped round bar, 20...round bar.

Claims (1)

[Scope of Claims] 1 One end or both ends of a heat-melting adhesive tube having an inner diameter larger than the outer diameter of the coated part of the optical fiber to be connected and inserted into the heat-shrinkable tube are connected to the optical fiber to be connected. 1. A member for reinforcing an optical fiber connection portion, characterized in that the member is pre-shrinked to have an inner diameter substantially equal to the outer diameter of the optical fiber coating. 2. For reinforcing an optical fiber connection portion as set forth in claim 1, wherein the contracted portion of the heat-melt adhesive tube protrudes in a funnel shape from the corresponding portion of the heat-shrinkable tube. Element. 3. A patent characterized in that a cushion material that can easily move on the optical fiber to be connected and has excellent adhesion is adhered to the inside of the funnel-shaped protrusion of the hot-melt adhesive tube. A reinforcing member for an optical fiber connection portion according to claim 2. 4. Claims 1 to 3, characterized in that the heat-melt adhesive tube is pre-shrinked so that its outer diameter is approximately equal to the inner diameter of the heat-shrinkable tube corresponding portion. A reinforcing member for an optical fiber connection portion as described in any of the above.