JP2013025056A - Optical fiber cable - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a low-cost, simply structured optical fiber cable that is used for a seabed non-relay system for a short distance, or across a shallow sea, a river, or a lake.SOLUTION: An optical fiber cable 1 comprises: an optical fiber part; a pressure resistance layer 2 that is cylindrical, and that is formed of a plurality of metal, fan-shaped, divided individual pieces 2a jacketing the optical fiber part; a metal coating layer 3 that includes a contact part 7 where one side of a metal tape jacketing the pressure resistance layer overlaps the other end of the metal tape in the longitudinal direction; and an insulation coating layer 4 that jackets the metal coating layer with insulation material.

Description

  The present invention relates to a waterproof and pressure-resistant structure for an underwater optical fiber cable.

JP 2002-196200 A JP 2005-292838 A

  In recent years, information and communication technology has spread all over the world, and long-distance optical fiber cables have been laid to network around the world. Among them, the submarine cable with built-in optical fiber, that is, the optical submarine cable, is placed in the harsh environment of the deep sea, so it can withstand the water pressure at that depth, the tensile property that can withstand laying / recovery, Waterproof characteristics and running water prevention characteristics (preventing water from moving in the longitudinal direction of the cable) are required. For this reason, optical submarine cables such as those shown in FIGS. 3 to 4 have already been proposed.

3A and 3B are an external view and a cross-sectional view of the optical submarine cable 20 of Patent Document 1. FIG.
The optical submarine cable 20 shown in FIG. 3 has a pressure-resistant layer 27 made of a metal divided piece 27a divided into three pieces around an optical fiber 12, and a tensile strength steel wire 22 made of a twisted body of hard steel wire thereon. Further, a metal tube 23 is formed, and an insulating coating layer 24 serving as a jacket is further laminated around the metal tube 23.
The gap between the optical fibers 12 is filled with a compound 25, and the waterproof compound 21 is filled between the divided pieces 27a and the hard steel wire as a water running prevention material.
The metal tube 23 is a metal layer that binds and seals the tensile strength steel wire 22 and serves as a power feeding path to the repeater. Usually, a metal tape made of copper, aluminum, or the like is vertically attached and welded to reduce the diameter (narrow down). It is formed in a shape.

The optical cable unit 30 of Patent Document 2 shown in FIG. 4 is obtained by covering the optical waveguide 13 with a metal tube 31. A space between the optical waveguide 13 and the metal tube 31 is filled with a filling compound (compound). This prevents water from moving in the longitudinal direction of the cable.
The metal tube 31 includes an austenite (steel) layer 31b and a copper layer 31c. These are formed by stacking a copper tape and an austenite (steel) tape and vertically attaching them to the optical waveguide 13. At the seam of each tape, a seam 31a of the austenite layer 31b and a seam 31d of the copper layer 31c are formed above and below.
By welding the joint 31a, the poured welding heat penetrates the wall thickness of the austenite layer 31b, and the joint 31d of the copper layer 31c is welded together. Welding can be processed in one place, and both copper and austenite are welded in the same process.

By the way, in the structure of the optical fiber cable shown in FIGS. 3 and 4, for example, in the case of the cable shown in FIG. 4, a metal tape is vertically attached and the joint is welded. For this reason, there is a concern that the internal optical waveguide 31 is exposed to a high temperature during welding, and its characteristics deteriorate. In addition, the welding process has a low working speed, which is a bottleneck in the productivity of optical fiber cables.
Further, since the optical fiber cable of FIG. 3 has a structure capable of withstanding the depth and high water pressure in the deep sea, the structure is complicated and the manufacturing cost is also increased.
In recent years, there has been a demand for an optical fiber cable having an inexpensive and simple structure that can be used in a short-distance undersea repeater system or used across shallow water, rivers, or lakes. However, since the optical fiber cable is suitable for the deep sea, there is a problem that the performance becomes high and expensive when used for shallow water.
An object of the present invention is to provide an optical fiber cable that solves such problems and is used in water with an inexpensive and simple structure.

  In order to achieve the above object, an optical fiber cable according to the present invention includes an optical fiber portion, a cylindrical pressure-resistant layer formed of a plurality of metal-shaped segment pieces around the optical fiber portion, and the pressure-resistant layer. A metal coating layer including a contact portion formed by vertically superimposing the periphery of the metal coating tape at a single location, and an insulating coating layer for coating the periphery of the metal coating layer with an insulating material.

  In another aspect of the invention, both surfaces of the divided portions are mirror-finished so that the mirror surfaces are in close contact with each other.

  In another aspect of the invention, a thin metal wire having a hardness smaller than that of each of the divided pieces is disposed at each upper portion of the joint of the divided pieces constituting the pressure-resistant layer, and the upper portion of the joint is sealed.

According to the configuration of the optical fiber cable according to the present invention, the tensile strength required when laying or pulling up in a submarine non-relay system, shallow water, rivers or lakes, or underground on land is sufficiently secured.
In addition, the conventional stranded wire and welding are not required, there is no restriction on the production speed due to the presence of the stranded wire machine or welder, the structure is extremely simple, and the production is efficient and inexpensive. Can do.
Furthermore, since the metal coating layer is formed so as to overlap the periphery of the pressure-resistant layer, it is possible to prevent water from entering the cable and running water as much as possible.

It is explanatory drawing of a structure of the optical fiber cable of the 1st Embodiment of this invention. It is explanatory drawing of a structure of the optical fiber cable of the 2nd Embodiment of this invention. It is explanatory drawing of the structure of the conventional optical submarine cable. It is explanatory drawing of the structure of the conventional optical submarine cable.

Hereinafter, embodiments of the present invention will be described in the following order.
<1. First embodiment of the present invention>
<2. Second embodiment of the present invention>

<1. First embodiment of the present invention>

FIG. 1 is a sectional view showing an optical fiber cable according to a first embodiment of the present invention.
As shown in FIG. 1, the optical fiber cable 1 includes an assembly of optical fiber cores 10 and a pressure-resistant layer 2 constituted by a fan-shaped metal piece 2 a divided into three pieces provided around the optical fiber cable 10. The pressure-resistant layer 2 is composed of a metal coating layer 3 in which the periphery of the pressure-resistant layer 2 is covered vertically with a metal tape, and an insulating coating layer 4 as an outer cover formed thereon. Although not shown, a protective iron layer may be formed by twisting an armored iron wire around the insulating coating layer 4.

  The quantity of the optical fiber core wire 10 is not limited to a specific quantity. The quantity may be one and is determined as necessary. A compound for preventing running water can be injected between the optical fiber core wire 10 and the pressure resistant layer 2.

  The pressure | voltage resistant layer 2 consists of the division | segmentation piece 2a divided into three, these are faced | matched vertically and the optical fiber core wire 10 is covered. The breakdown voltage layer 2 is made of a metal having good breakdown voltage characteristics, and is typically made of iron. The number of divisions of the metal pressure-resistant layer 2 is not limited to such three divisions, but three divisions are appropriate for handling.

  The metal coating layer 3 is formed by covering a metal tape around the pressure-resistant layer 2 vertically in the longitudinal direction of the optical fiber cable, and forming the contact portion 7 by overlapping the ends of the metal tape vertically in one place. It is. A metal tape with an adhesive EAA (copolymer resin of ethylene and acrylic acid) may be used as necessary in order to increase the adhesion to the insulating coating layer 4.

The metal coating layer 3 stops the divided pieces 2a from opening. That is, by overlapping the metal tape to form the contact portion 7, sufficient waterproofness can be secured and the divided pieces 2 a of the pressure-resistant layer 2 can be integrated. In this case, it is preferable that the metal coating layer 3 is in close contact with the pressure-resistant layer 2 so that water can be prevented from entering from the respective joint upper portions 8 of the divided pieces 2a.
Moreover, it is preferable that the metal coating layer 3 is comprised with the metal which has big elongation at break, for example, an iron tape so that it may be hard to fracture | rupture.

The upper drawing of FIG. 1 is an enlarged view of the state of the contact portion 7 in which the ends of the metal tape forming the metal coating layer 3 are vertically overlapped at one place.
The left view of the enlarged view is a view immediately after the ends of the metal tape are overlapped. Since they are simply overlapped, a gap 9 is formed at the end of the overlapped contact portion 7. As a result, the metal coating layer 3 is finally provided, so that the contact portion 7 overlapped by the pressure as shown in the right figure of the enlarged view can be in close contact with the metal tape overlapping the upper surface.

Next, the manufacturing method of the optical fiber cable which concerns on 1st Embodiment is demonstrated.
The pressure-resistant layer 2 sends fan-shaped divided pieces 2a, which are divided into a plurality of pieces in the circumferential direction, to the outer periphery of the optical fiber core wire 10 from three directions in the longitudinal direction of the outer peripheral surface of the optical fiber core wire 10 that is continuously supplied. These are attached to form a cylinder so that the inner peripheral surface is in close contact with the outer peripheral surface of the optical fiber core wire 10. The divided piece 2a is made of iron.

  After forming the pressure resistant layer 2 along the outer peripheral surface of the optical fiber core wire 10 along the plurality of divided pieces 2a, the metal tape is formed into a tube shape so as to wrap the pressure resistant layer 2 with the metal tape, and the end of the metal tape is The metal contact layer 3 is formed by forming the overlapping contact portion 7.

  Next, the circumference | surroundings of the metal coating layer 3 are coat | covered with the insulation coating layer 4, and an optical fiber cable is manufactured.

By configuring in this way, it is possible to omit the process of using a twisting machine when twisting a high tensile strength wire and a welding machine at the time of welding, so that the manufacturing process can be simplified while preventing fiber damage during welding, A low-cost optical fiber cable suitable for use in shallow water, rivers, lakes, and the like, and for short-distance optical communication without relay can be provided.
Furthermore, the metal coating layer 3 is superimposed on the periphery of the pressure-resistant layer 2 to form a contact portion 7, and the insulating coating layer 4 is formed on the metal coating layer 3, whereby the metal coating layer 3 is insulated. The contact portion 7 that is in close contact with the layer 4 is pressed and intimately pressed by the insulating coating layer 4 to prevent water from entering from the seam 8 and to ensure waterproofness and airtightness.
Further, when the divided piece is iron, it generally has a strength of a tensile strength of 1-2 tons, and is suitable for laying in a relatively shallow and stable shallow sea, lake water, or the like.

  Although the first embodiment has been described above, as a modified example, the joint surface of each split piece 2a may have a mirror finish, and the joint may be in close contact. Thereby, waterproofness, running water prevention property, and airtightness can further be improved.

<2. Second embodiment of the present invention>
2A and 2B are cross-sectional views showing an optical fiber cable according to a second embodiment of the optical fiber cable according to the present invention. In this figure, parts that are the same as those in FIG. 1 are given the same reference numerals, and descriptions of the same contents are omitted.
FIG. 2A shows a state in which, after forming the pressure-resistant layer 2 along the outer peripheral surface of the optical fiber core wire 10 with the divided pieces 2a, the fine metal wires 5 according to the present embodiment are arranged on the upper portion 8 of the joint. FIG.
As shown in FIG. 2 (a), a metal thin wire 5 is arranged in the longitudinal direction of the optical fiber cable at each joint upper part 8 of the divided piece 2a. The material of the thin metal wire 5 is preferably a metal material having a hardness lower than that of the metal material forming the divided piece 2a and having a large elongation at break.
As shown in the enlarged view of FIG. 2A, the upper portion 8 of the joint is processed so that the corners of the outer peripheral surface and the mating surface are slightly rounded when the divided pieces 2a are abutted vertically. A depression resulting from is formed. The fine metal wire 5 is arranged in this recess.

FIG. 2B is a cross-sectional view when the optical fiber cable according to the present embodiment is completed.
As shown in FIG. 2B, the outer periphery of the pressure-resistant layer 2 in which the fine metal wires 5 are arranged and in close contact is first covered with the metal coating layer 3, and the outer periphery thereof is further covered with the insulating coating layer 4. It becomes.
For this reason, as shown in the enlarged view of FIG. 2B, the metal thin wire 5 receives pressure from the metal coating layer 3 and is deformed, and the original round cross-sectional shape becomes flat. As a result, the fine metal wires 5 are tightly sealed so as to fit into the recesses in the upper portion 8 of the joint piece 2a.
With such a configuration, an optical fiber cable excellent in waterproofness can be easily realized.
As the thin metal wire 5 to be in close contact with the divided piece 2a, a metal material having a smaller hardness than the metal material forming the divided piece 2a and having a large elongation at break is preferable. For example, copper, copper alloy, aluminum, aluminum alloy, etc. be able to. As a result, waterproofness and running water prevention are improved, and at the same time, flexibility required for the optical fiber cable is maintained. In addition, when airtightness is further improved and there is a concern about external damage due to tidal currents such as undersea laying or river crossing in the shallow water, when using it for unrepeated short-distance submarine cables, or when burying underground on land Is preferred.

  1, 6 Optical fiber cable, 2, 27 Pressure-resistant layer, 3 Metal coating layer, 4 Insulation coating layer, 5 Metal fine wire, 8 Joint upper part, 20 Optical submarine cable, 22 Tensile steel wire, 23 Metal tape, 24 Insulation coating layer , 30 Optical cable unit, 31 Metal tube

Claims (3)

An optical fiber section;
A cylindrical pressure-resistant layer composed of a plurality of segmented pieces of metal around the optical fiber portion; and
A metal coating layer including a contact portion formed by vertically superimposing the periphery of the pressure-resistant layer vertically in one place with a metal tape;
An insulating coating layer for coating the periphery of the metal coating layer with an insulating material;
An optical fiber cable.   The optical fiber cable according to claim 1, wherein both surfaces of the joining portion of the divided pieces are mirror-finished and the mirror surfaces are in close contact with each other.   The thin metal wire having a hardness smaller than that of the divided piece is disposed at each upper part of the joint of the divided piece constituting the pressure-resistant layer, and the thin metal wire seals the upper part of the joint. Item 3. An optical fiber cable according to Item 2.

Images