JPH085847A - Gastight termination structure of optical fiber cable - Google Patents

Abstract

PURPOSE:To provide a gastight termination structure of an optical fiber cable which is capable of preventing infiltration and leakage of water and air through the inside of optical fiber cords and is adequate particularly for connection to a gastight waterproof type light transmission device. CONSTITUTION:This gastight termination structure 1 of the optical fiber cable is formed by removing cord protective layers 5 of the optical fiber cords 3 extending from the ends of the optical fiber cable 2 over the prescribed length to expose the protective layers of coated optical fibers 4. Hermetic sealing parts 6 consisting of adherable resins are formed in the protective layers of the coated optical fibers 4 and further, these hermetic sealing parts 6 and the ends of the optical fiber cables 2 are so sealed as to be enclosed by sealing materials 8, by which the structure described above is completed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical fiber cable airtight termination structure, and more particularly to an optical fiber cable airtight termination structure suitable for connection with an airtight waterproof optical transmission device.

[0002]

2. Description of the Related Art Optical fiber cables are regarded as promising communication means because they can transmit a larger amount of signals than electric wires. As shown in FIG. 3, the optical fiber cable 20 is usually configured by converging a plurality of optical fiber cords 21 and accommodating them in an outer sheath 22. When connecting the transmission devices using the optical fiber cable 20, the optical connector 23 provided at the tip of the optical fiber cord 21 extending from the end of the optical fiber cable 20 is hermetically sealed. It is performed by connecting to the airtight waterproof optical transmission device 25 housed in the container 24.

The boundary portion of the optical fiber cable 20 where the optical fiber cord 21 is exposed is sealed with a sealing material 26 for protection and waterproofing of the optical fiber cord 21, and a rubber boot 27 is fitted on the outside thereof. A so-called termination structure 28, which has been airtightly processed, is usually adopted. With such a termination structure 28, as shown in FIG. 4 (XX sectional view of FIG. 3), the periphery of each optical fiber cord 21 is sealed by the sealing material 26 and exposed.
External water or air is prevented from entering the inside of the optical fiber cable 20 along the outer peripheral surface of the optical fiber cable 1. Further, a portion of the airtight container 24 where the optical fiber cord 21 is inserted is hermetically sealed by a sealing material 29 to prevent intrusion of water or air from the outside.

Another example of this type of optical fiber cable hermetically terminating structure is shown in FIGS. 5 and 6 (FIG. 5).
AA cross-section) of JP-A-58-158.
There is one disclosed in Japanese Patent No. 609. In the optical fiber cable termination structure 31, the optical fiber core wire 32 extending from the end portion of the optical fiber cable 20 is inserted into a hollow rubber tube 33 having a slit, and the rubber tube 33 having a slit is provided with a rubber tube 34 having a U-shaped groove. Of the O-ring rubber tube 36, and the outer side of the O-ring rubber tube 36 is fitted with the sealing material 35. The sleeve 37 holds the O-ring rubber tube 36 at the end of the optical fiber cable 20. It is configured to be fitted and inserted into the opening portion of the pressing metal fitting 38 continuous with. According to the optical fiber cable termination structure 31, it is possible to prevent the airtightness of the optical fiber cable termination structure 28 having the structure shown in FIGS. 3 and 4 from being deteriorated due to defective filling of the sealing material 26.

[0005]

By the way, as shown in FIGS. 7 and 8, the optical fiber cord 21 has a protective layer 40 covering an optical fiber element wire 39 consisting of a core and a clad at the center thereof. There is an optical fiber core wire 41 to be constructed, and the outer circumference of the optical fiber core wire 41 is covered with a cord protection layer 42. The cord protection layer 42 is a Kevlar (registered trademark)
And the like, and the outer sheath 42B. Here, in order to secure the flexibility of the optical fiber cord 21 itself and to facilitate the connection work, a boundary surface 43A between the optical fiber core wire 41 and the tension fiber 42A,
And an interface 43 between the shaft tension fiber 42A and the sheath 42B
B is stored only by abutting the inner and outer peripheral surfaces thereof, and is not fixed by adhesion or the like.

Therefore, these boundary surfaces 43A and 43B are
Microscopically, it is a gap through which water and air can sufficiently pass, and the optical fiber cable termination structure 2 shown in FIGS.
In FIG. 8, although it is possible to prevent water and air from penetrating into the inside of the optical fiber cable 20 along the outer peripheral surface of the optical fiber cord 21 exposed to the outside, the boundary surfaces 43A and 43B are It is not possible to prevent water or air from entering through. The amount of water or air that enters through these boundary surfaces 43A and 43B is a small amount in the short term, but becomes a non-negligible amount in long-term use. Moreover, the anti-tensile fiber 42A forming the cord protection layer 42 has many voids, and allows water and air to easily enter.

In the optical fiber cable termination structure 31 shown in FIGS. 5 and 6, the optical fiber core wire 3 is also used.
2 and the rubber tube 33 with a slit are not fixed to each other, and water and air enter through the boundary surface between them.

The existence of the structural water and air intrusion path of the optical fiber cord 21 becomes more important especially in connection with the airtight waterproof type optical transmission device 25 housed in the airtight container 24. That is, the airtight waterproof optical transmission device 25 is configured to maintain its waterproof effect by having an airtight structure, and therefore the airtight container 24 seals the insertion portion of the optical fiber cord 21 with the sealing material 29. All the parts that interfere with the outside are hermetically sealed.

However, since the optical fiber cord 21 has microscopic water and air intrusion paths as described above, it is unavoidable that air inside the airtight container 24 leaks through these intrusion paths. As a result, the airtightness is destroyed and the waterproof effect cannot be obtained. However, the optical fiber cable terminating structures 28 and 31 having the conventional structure cannot block the microscopic intrusion route of the optical fiber cord 21, and therefore, in connection with the airtight waterproof optical transmission device 25,
It was difficult to maintain airtightness.

The present invention has been made to solve such problems and drawbacks, and has a structure of an optical fiber cord such as an interface between an optical fiber core wire and a cord protective layer and a tensile strength fiber constituting the cord protective layer. (EN) An airtight termination structure for an optical fiber cable capable of preventing water or air from entering through an inevitable microscopic gap and maintaining high airtightness particularly in connection with an airtight waterproof optical transmission device. With the goal.

[0011]

In order to achieve the above object, in an optical fiber cable hermetically-sealed structure according to the present invention, a cord protective layer of an optical fiber cord extending from an end portion of the optical fiber cable is removed over a predetermined length. And a protective layer of the optical fiber core wire is exposed, and a sealing portion made of a resin that can be bonded to the protective layer of the optical fiber core wire at the exposed portion of the optical fiber core wire and the exposed cross-section portion of the cord protective layer. Is formed, and further, the sealing portion and the end portion of the optical fiber cable are included and sealed by a sealing material.

In order to achieve the same object, the optical fiber cable hermetically-sealed structure according to the present invention has an optical fiber in which the cord protective layer of the optical fiber cord extending from the end of the optical fiber cable is removed over a predetermined length. The protective layer of the core wire is exposed, and the exposed portion of the optical fiber core and the exposed cross-section portion of the cord protective layer are sealed with an airtight tape, and the outer side of the optical fiber cable end is covered with a sealing material. It is characterized in that it is sealed so as to include the portion. The airtight termination structure of the optical fiber cable can be suitably used particularly for connection with an airtight waterproof optical transmission device.

[0013]

Operation: The cord protective layer of the optical fiber cord extending from the end of the optical fiber cable is removed over a predetermined length to expose the protective layer of the optical fiber core, and the exposed portion of the optical fiber core and the shaft tension. The interface with the fiber, the interface between the anti-tensile fiber and the sheath and the anti-tensile fiber are separated,
The invasion route of water or air entering from the optical connector side provided at the end of the optical fiber cord or water or air entering from the optical fiber cable side is blocked. Then, the exposed portion of the optical fiber core wire and the exposed cross-sectional portion of the cord protective layer are sealed with a resin or an airtight tape that can be bonded to the protective layer of the optical fiber core wire to protect the optical fiber core wire, Water and air are prevented from entering through the exposed outer peripheral surface of the optical fiber core. Further, by sealing the sealed portion made of the resin or the airtight tape so as to include the end portion of the optical fiber cable with a sealing material, the boundary portion between the end portion of the optical fiber cable and the optical fiber cord is protected and the outside world is protected. Water and air are prevented from entering the inside of the optical fiber cable along the outer peripheral surface of the optical fiber cord exposed to the air. In this way, it is possible to reliably prevent water and air from entering through the inside and the outside of the optical fiber cord.

In addition to the above, it is possible to completely block the microscopic water or air intrusion path of the optical fiber cord, so that good airtightness can be maintained in the connection with the airtight waterproof optical transmission device. You can

[0015]

Embodiments of the present invention will now be described in more detail with reference to the accompanying drawings. 1 is a cross-sectional view of a main part showing an embodiment of an optical fiber cable termination structure to which an optical fiber cable airtight treatment method according to the present invention is applied, and FIG.
FIG. 6 is a cross-sectional view of a main part showing a state in which an airtight waterproof optical transmission device is connected using the optical fiber cable airtight termination structure of FIG. The optical fiber cable termination structure 1 according to the present invention is for hermetically sealing the boundary between the end of the optical fiber cable 2 and the optical fiber cord 3 extending from the end. Here, the optical fiber cord 3 has the same structure as a known optical fiber cord (for example, the optical fiber cord 21 shown in FIG. 8), and is configured by coating the optical fiber core wire 4 with a cord protective layer 5. .. The optical fiber core wire 4 is similar to the structure shown in FIG. 7, and is formed by covering the optical fiber element wire 39 composed of the core and the clad with the protective layer 40.

In order to complete the optical fiber cable termination structure 1, first, the cord protective layer 5 of the optical fiber cord 3 extending from the end of the optical fiber cable 2 is removed over a predetermined length, and the optical fiber core wire is removed. 4 to expose the protective layer 40 (see FIG. 7). Then, the sealing portion 6 is formed so as to completely cover the exposed portion of the optical fiber core wire 4 and the exposed cross-section portion of the cord protection layer 5. It is preferable that the sealing portion 6 is made of a resin that can adhere to the protective layer 40 of the optical fiber core wire 4 or that has high adhesiveness. For example, the protective layer 40 of the optical fiber core wire 4 is generally made of a nylon resin, but is formed by applying a silicone resin that can be bonded to the nylon resin in an uncured state and curing it. . Here, as the silicone resin, R
TV (room temperature curing type) silicone resin is particularly preferable in terms of workability.

As described above, the sealing portion 6 is fixed to the exposed portion of the optical fiber core wire 4 and the exposed cross-sectional portion of the cord protective layer 5, so that the inside of the optical fiber cord 3, for example, the optical fiber core. The water and air that have propagated through the boundary surface 7 between the wire 4 and the cord protection layer 5 reach the sealed portion 6 and are blocked, and the water and air enter through the exposed outer peripheral surface of the optical fiber core wire 4. Is prevented. Also,
In addition to the function of sealing the inside of the optical fiber cord 3, the sealing portion 6 prevents the optical fiber core wire 4 from being affected by distortion caused by shrinkage caused by hardening of the filling material 8 when the filling material 8 described later is formed. It also functions as a cushioning material.

After the sealing portion 6 is formed, it is sealed with a sealing material 8 so as to include the sealing portion 6 and the boundary portion between the end portion of the optical fiber cable 2 and the optical fiber cord 3. The sealing with the filling material 8 is performed by mounting a predetermined molding frame on the sealing portion and injecting an uncured epoxy resin, an epoxy adhesive, a non-foaming urethane resin or the like into the molding frame to cure it. To be done. The filling material 8 protects the boundary between the end of the optical fiber cable 2 and the optical fiber cord 3, and water and air are transmitted along the outer peripheral surface of the optical fiber cord 3 exposed to the outside world. Is prevented from entering inside. Also, the filler 8
By coating the rubber boot 9 with the rubber boot 9, the waterproof effect and the end portion of the optical fiber cable 2 and the optical fiber cord 3 are provided.
It is possible to further improve the protection of the boundary portion with and to make the appearance of the boundary portion beautiful. From the above,
The optical fiber cable airtight termination structure 1 is completed.

The optical fiber cable airtight termination structure 1 according to the present invention can be variously modified. For example, in forming the sealing portion 6, an airtight tape (not shown) is used to expose the optical fiber core wire 4 instead of a resin that can be adhered to the protective layer 40 of the optical fiber core wire 4 or has high adhesiveness. By winding and sealing both the portion and the exposed cross-section of the cord protection layer 5, the same effect as the above can be obtained. The airtight tape is also preferably capable of adhering to the protective layer 40 of the optical fiber core wire 4 or has high adhesiveness.

Further, the optical fiber cable airtight termination structure 1 according to the present invention can be suitably used for connection with the airtight waterproof optical transmission device 25. Optical fiber cable airtight termination structure 1
2 is connected to the airtight waterproof optical transmission device 25 by connecting the end of the optical fiber cord 3 to the airtight waterproof optical transmission device 25 housed in the airtight container 24, as shown in FIG. Here, the airtight container 24 is installed on the floor 30 by hermetically sealing the insertion portion of the optical fiber cord 3 with the sealing material 29 and performing airtight construction. These airtight structures are the same as the conventional one (see FIG. 3). However, in the airtight termination structure 1 portion of the optical fiber cable, the air ingress path inside the optical fiber cord 3 is blocked by the sealing portion 6, so that the air inside the airtight container 24 does not leak further. The airtightness of the airtight container 24 is maintained well.

[0021]

As described above, according to the optical fiber cable airtight processing method and the optical fiber cable airtight termination structure according to the present invention, the cord protective layer of the optical fiber cord extending from the end portion of the optical fiber cable is provided. By removing over a predetermined length to expose the protective layer of the optical fiber core, the interface between the optical fiber core and the anti-tensile fiber, the interface between the anti-tensile fiber and the sheath and the anti-tensile fiber are exposed at this exposed portion. Water and air entering from the optical connector side provided at the end of the optical fiber cord or the optical fiber cable side, or the entering path of water or air entering from the optical fiber cable side are blocked. Then, the exposed portion of the optical fiber core wire and the exposed cross-sectional portion of the cord protective layer are sealed with a resin or an airtight tape that can be bonded to the protective layer of the optical fiber core wire to protect the optical fiber core wire, Water and air are prevented from entering through the exposed outer peripheral surface of the optical fiber core. Further, by sealing the sealed portion made of the resin or the airtight tape so as to include the end portion of the optical fiber cable with a sealing material, the boundary portion between the end portion of the optical fiber cable and the optical fiber cord is protected, and the outside world is protected. Water and air are prevented from entering the inside of the optical fiber cable along the outer peripheral surface of the optical fiber cord exposed to the air. In this way, it is possible to reliably prevent water and air from entering through the inside and the outside of the optical fiber cord. In addition to the above, it is possible to completely block the microscopic water or air intrusion path of the optical fiber cord, so that good airtightness is maintained in connection with the airtight waterproof optical transmission device, and a high waterproof effect is obtained. Can be maintained for a long time.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of essential parts showing an embodiment of an airtight termination structure for an optical fiber cable according to the present invention.

FIG. 2 is a cross-sectional view of essential parts showing a state in which an airtight waterproof optical transmission device is connected using the airtight termination structure of the optical fiber cable of FIG.

FIG. 3 is a sectional view of an essential part showing a conventional optical fiber cable airtight termination structure.

4 is a sectional view taken along line XX of FIG.

FIG. 5 is a sectional view of an essential part showing another conventional airtight termination structure of an optical fiber cable.

6 is a cross-sectional view taken along the line AA in FIG.

FIG. 7 is a cross-sectional view of a main part of an optical fiber cord.

FIG. 8 is a cross-sectional view of a main part of an optical fiber core wire.

[Explanation of symbols]

 1 Optical Fiber Cable Airtight Termination Structure 2 Optical Fiber Cable 3 Optical Fiber Cord 4 Optical Fiber Core 5 Cord Protective Layer 6 Sealing Part 7 Boundary 8 Filler 9 Rubber Boot

Claims (3)

[Claims] 1. A cord protective layer of an optical fiber cord extending from an end portion of an optical fiber cable is removed over a predetermined length to expose a protective layer of an optical fiber core wire, and
A sealing portion made of a resin that can adhere to the protective layer of the optical fiber core is formed on the exposed portion of the optical fiber core and the exposed cross-section of the cord protective layer, and the sealing portion and the optical fiber are further filled with a filler. An optical fiber cable hermetically terminating structure, characterized in that the cable ends are included and sealed. 2. The cord protective layer of the optical fiber cord extending from the end portion of the optical fiber cable is removed over a predetermined length to expose the protective layer of the optical fiber core and the exposed portion of the optical fiber core. And the exposed cross-section of the cord protection layer is sealed with an airtight tape, and the outside is further sealed with a filler so as to include the end of the optical fiber cable. Termination structure. 3. The optical fiber cable airtight termination structure according to claim 1, which is used for connection with an airtight waterproof optical transmission device.