JP2009198779A - Optical fiber cable - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical fiber cable which can be easily wired and laid in laid piping in a building and can smoothly construct an optical fiber network. <P>SOLUTION: The optical fiber cable 1 is bundled by intertwisting only a plurality of optical elements 2 each of which is provided with a cover layer 7 formed on the circumference of a coated optical fiber 5 while being twisted back with a prescribed pitch. The optical fiber cable 1 can be flattened such that the contour of the optical fiber cable 1 is conformed to a space by moderately disordering the arrangement of respective optical elements 2. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an optical fiber cable suitable for use in constructing an optical fiber network.

  There is an optical fiber network called FTTH (Fiber To The Home) that guides an optical fiber to an individual user (house-to-house). When constructing this optical fiber network, an optical element is formed by covering an optical fiber with a tensile layer together with a coating layer, and an optical fiber cable in which a plurality of optical elements are bundled is laid, and each optical element is individually connected from this trunk line. Will be distributed to all users. In order to install optical fiber cables in apartment buildings such as condominiums, it is more cost-effective to install them in existing pipelines in the building than to establish new installation routes. Laying work in the road is underway.

  As an example of an optical fiber cable for laying in such an existing pipe line, a flat optical drop cable unit in which optical fibers and tensile wires are arranged on a plane and collectively coated is used as a central tensile member. What gathered together on the perimeter is known (for example, refer to patent documents 1).

JP 10-333000 A

  When an optical fiber cable is constructed by twisting a plurality of optical drop cable units on the outer periphery of the central strength member as described above, the pipe line is used when laying in the existing pipe line 101 as shown in FIG. In a space that is narrowed by the existing existing cable 102, it becomes difficult to pass the optical fiber cable 103.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an optical fiber cable that can be easily routed in an existing pipeline in a building and can be smoothly constructed.

  The optical fiber cable of the present invention capable of solving the above-described problems is a bundle of a plurality of optical elements each provided with a coating layer around the optical fiber core wire, being twisted while being twisted back at a predetermined pitch. It is characterized by being.

  In the optical fiber cable according to the present invention, the optical element has a structure in which one tensile strength body is provided on each side of the optical fiber core wire in parallel with the optical fiber core wire and is collectively covered with the coating layer, Preferably, the structure includes only the coating layer around the optical fiber core, or the structure includes the tensile fiber and the coating layer around the optical fiber core. The elements may be connected in parallel.

Moreover, the optical fiber cable which concerns on this invention WHEREIN: It is preferable that the said several optical element is twisted together and unitized, and the said unit is twisted in multiple numbers.
Furthermore, it is preferable that the twisting pitch of the unit is larger than the twisting pitch of the optical element.

  The optical fiber cable of the present invention is configured by bundling only a plurality of optical elements having a coating layer on the outer periphery of the optical fiber core wire. Diameter can be achieved. Furthermore, since a plurality of optical elements are twisted and bundled while being twisted back at a predetermined pitch, it is easy to integrate as a cable without wrapping a bind wire or the like around the optical element, and to the existing pipeline. The arrangement of the optical elements varies moderately during the wiring, and the outer shape of the cable can be deformed in accordance with the shape of the limited narrow space. Therefore, the optical fiber cable of the present invention can be easily routed into the existing pipeline and laid, and the optical fiber network can be constructed smoothly.

Hereinafter, an example of an embodiment of an optical fiber cable according to the present invention will be described with reference to FIGS.
FIG. 1 is a cross-sectional view of an optical fiber cable, and FIG. 2 is a cross-sectional view when the optical fiber cable of FIG. 1 is passed through an existing pipeline.

  As shown in FIGS. 1A to 1C, an optical fiber cable 1 includes a plurality of optical elements such as drop cables, indoor cables, and optical cords used for applications such as FTTH (16 in the example of FIG. 1). ) A cable that is assembled. The optical fiber cable 1 is in a state in which a plurality of long optical elements 2 laid up to each user (a separate residence) are twisted together while being twisted back at a predetermined twist pitch (for example, 200 mm to 1200 mm). , Integrated.

  Here, “with twisting (twisting rate 100%)” means that the direction (posture) in the cross section perpendicular to the central axis of the optical element 2 is the same over the longitudinal direction of the optical fiber cable 1, while the optical fiber. This means that the cable 1 is spirally arranged around the central axis of the cable 1. In the case of “no twisting (twisting rate 0%)”, the optical fiber cable 1 has a central axis so that the same portion in the cross section of the optical element 2 always faces the central axis of the optical fiber cable 1. On the other hand, it is in a spiral arrangement around it, and the orientation in the cross section of the optical element 2 is rotated 360 ° with one twist pitch.

  Since the optical element 2 of the present embodiment is twisted in a “twisted” state, a force that integrates with each other acts, and even if a binding wire or the like is not wound around the outer periphery, it is usually light. The elements 2 are assembled without being separated.

  The optical element 2 in FIG. 1A includes two optical fiber cores 5 in parallel with two optical fiber cores 5 in which a glass fiber composed of a core and a clad is provided with a coating such as an ultraviolet curable resin. Tensile strength members 6 are provided side by side on both sides of the structure, and a coating layer 7 is provided on the outer periphery thereof. Note that the number of optical fiber cores 5 included in one optical element 2 can be changed as appropriate.

  The covering layer 7 of the optical element 2 in FIG. 1A has a substantially rectangular shape whose cross section is long in the direction in which the pair of strength members 6 are arranged. Further, the coating layer 7 is formed with an R chamfer in a square shape, and a pair of concave portions 9 having a V-shaped cross section with the optical fiber core wire 5 interposed therebetween. The pair of recesses 9 is for enhancing the ease of cutting the coating layer 7 when the optical fiber core wire 5 is led out. In addition, it is good also as a shape which makes both R chamfering of a short side into one continuous arc, and forms the one side of a recessed part in the edge part of this arc. Moreover, it is good also as a shape which does not form a recessed part in the coating layer 7. FIG.

  Although the coating layer of the conventional indoor cable was formed from, for example, low density polyethylene (LDPE) or linear low density polyethylene (L-LDPE), in this embodiment, the coating layer 7 is high density polyethylene (HDPE), It is made of a low friction resin such as polypropylene (PP) or fluorine resin. Or the coating layer 7 is formed from the synthetic resin containing a lubricating material. Since high density polyethylene and polypropylene have excellent tackiness, they have lower friction than conventional low density polyethylene and linear low density polyethylene even without a lubricant.

  The optical element 2 constituting the optical fiber cable 1 in FIG. 1B includes only the coating layer 7 around the optical fiber core wire 5, and the optical element constituting the optical fiber cable 1 in FIG. 2 includes a tensile fiber 6 a such as an aramid fiber and a coating layer 7 around the optical fiber core wire 5. The optical fiber cable 1 shown in FIG. 1C provided with the tensile strength fiber 6a has an allowable tension higher than that of the optical fiber cable 1 shown in FIG. The optical fiber cable 1 shown in FIGS. 1B and 1C has a smaller diameter and lower rigidity than the optical fiber cable 1 shown in FIG. 1A, so that it is easier to bend and saves space. The lineability is good due to the conversion.

  As shown in FIG. 2, when the existing pipe line 11 of a building such as a condominium or the like to be laid through the optical fiber cable 1 has a narrow space that can be connected by the existing cable 12, In the optical fiber cable 1, the arrangement of the optical elements 2 varies moderately, and the outer shape of the optical fiber cable 1 can be flattened according to the space. Accordingly, the optical fiber cable 1 can be easily routed into the existing pipeline 11 and laid, and the optical fiber network can be constructed smoothly. Further, since there is no need to wrap a bind line or the like, the bind line or the like is caught in the existing pipe line 11 and does not hinder the line work.

  Further, since the optical fiber cable 1 does not need to be provided with a tensile body such as a metal wire unlike the cable of FIG. 6, the diameter of the cable can be reduced, which also improves the easiness of wiring. ing. In particular, in a cable in which a tensile body is arranged at the center of the cable as shown in FIG.

  The optical fiber cable 1 shown in FIG. 1 has a coating layer 7 for identifying each optical element 2 in the branch wiring for each optical element 2 after the trunk line is laid in the existing pipeline 11. Characters for identification are printed on the surface.

  Optical fiber cables 1a, 1b, and 1c shown in FIG. 3 are examples for improving the distinguishability by allowing the optical element 2 to be distinguished into a plurality of units when the number of optical elements 2 is large.

  In FIG. 3A, in order to distinguish the 30 optical elements 2 constituting the optical fiber cable 1a into four units 13, four colors of the coating layer 7 are used for each color. In this example, each unit can be identified by changing the marking color even if the color of the coating layer of each unit is the same. In FIG. 3 (b), in order to distinguish the 30 optical elements 2 constituting the optical fiber cable 1b into the four units 13, the coarsely wound strings 14 of different colors are wound around the four units 13, respectively. Units 13 are assembled together. In FIG. 3 (c), in order to distinguish the 32 optical elements 2 constituting the optical fiber cable 1c into eight units 13, eight units 13 twisted for every four optical elements 2 are further They are twisted together. In the case of this example, the flexibility of the optical fiber cable 1c is improved by increasing the twist pitch for twisting the units 13 together than the twist pitch in each unit 13 (twist pitch of the four optical elements 2). In addition, the discrimination between the units is improved.

Moreover, you may change the structure of the optical element which comprises an optical fiber cable.
For example, as in an optical element 2a shown in FIG. 4A, the optical element 2 in FIG. 1B is connected in parallel, and two optical fiber cores 5 are arranged in parallel, The optical fiber core wire 5 may have a glasses-shaped cross-sectional outer shape in which coating layers 7 a formed in a substantially circular cross section are connected to each other.

  This optical element 2a has a structure that does not have a strength member, but has a shape in which two round optical cords are connected to improve the allowable tension. Further, two optical elements 2a are provided with one optical element 2a. An optical fiber core wire 5 is incorporated. Therefore, the optical fiber cable 1d in which the optical element 2a is twisted and bundled while being twisted is manufactured so as to have the same number of optical fiber cores 5 (for example, 32) using the optical element 2 shown in FIG. Compared to the optical fiber cable 1e shown in FIG. 4 (b), the diameter can be greatly reduced and the diameter can be reduced. Further, since the number of optical elements 2a can be reduced to half while maintaining the number of optical fiber cores 5 per cable, the distinguishability of each optical element 2a is also improved.

The optical element 2a is separated into one round optical cord (see FIG. 1 (b)) using the concave portion of the covering layer 7a located between the two optical fiber cores 5. You can also.
In the optical element 2a, tensile strength fibers such as aramid fibers (see FIG. 1C) may be disposed around the optical fiber core wire 5 in order to increase the allowable tension.

Next, the result of having tested about the twist pitch of the optical element in a fiber optic cable, and a lineability is shown.
The used optical fiber cable is made by twisting 30 optical elements 2 (cross section 1 mm × 2 mm) in a twisted manner like the optical fiber cable 1b shown in FIG. About 12 mm. The existing pipe line to be connected has an inner diameter of 28 mm, and a total of about 20 m provided with three bent portions as shown in FIG. In addition, an existing cable having a diameter of 15 mm and having a diameter of 0.5 mm × 30 pairs of telephone wires is laid in the existing pipeline.

  Then, nine types of optical fiber cables with different twisting pitches in the range of 50 mm to 4000 mm are prepared, and a wire string is attached to each end, and the wires are connected to the existing pipeline shown in FIG. The optical element was checked for availability and damage during the connection. The results are shown in the following table.

  As shown in the table, in the case of the twist pitches of 50 mm and 100 mm, it was impossible to pass through the third bent portion. This is because the twisting pitch is too short and the cable cross section could not be deformed well in accordance with the space. In addition, in the case of the twist pitches of 2000 mm and 4000 mm, the optical element was bent although it could be connected. This is because the twisting pitch is too long, the optical elements are too scattered, and one or more optical elements are caught on the existing cable.

  From this result, it can be seen that the optimum twist pitch is 200 mm to 1200 mm. However, this preferred range of the twist pitch is an example according to the above conditions, such as the size of the space in the existing pipeline, the bending condition of the existing pipeline, the diameter of the optical fiber cable, the number of optical elements constituting the optical fiber cable, etc. Therefore, the optimum twist pitch varies.

It is sectional drawing which shows the example of embodiment of the optical fiber cable which concerns on this invention. It is sectional drawing of the state which penetrated the optical fiber cable of FIG. 1 in the existing pipe line. It is sectional drawing which shows the example for the identification improvement of an optical element. It is sectional drawing which shows the example of other embodiment of the optical fiber cable which concerns on this invention. It is the schematic which shows the mode of the test which connects an optical fiber cable in the existing pipeline. It is sectional drawing which shows an example of the conventional optical fiber cable.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,1a-1e ... Optical fiber cable 2 ... Optical element 5 ... Optical fiber core wire 6 ... Tensile body 6a ... Tensile fiber 7 ... Coating layer 11 ... Existing pipe 12 ... Existing cable

Claims (7)

  An optical fiber cable characterized in that only a plurality of optical elements each provided with a coating layer around an optical fiber core wire are twisted and bundled while being twisted back at a predetermined pitch. The optical fiber cable according to claim 1,
An optical fiber cable, wherein the optical element is provided with one tensile body on each side of the optical fiber core in parallel with the optical fiber core and is collectively covered with the coating layer. The optical fiber cable according to claim 1,
The optical element includes only the covering layer around the optical fiber core wire. The optical fiber cable according to claim 1,
The optical element is provided with a tensile fiber and the covering layer around the optical fiber core. The optical fiber cable according to claim 1,
An optical fiber cable, wherein a plurality of optical elements are connected in parallel. An optical fiber cable according to any one of claims 1 to 5,
An optical fiber cable, wherein a plurality of optical elements are twisted together to form a unit, and the units are twisted together. The optical fiber cable according to claim 6,
An optical fiber cable, wherein the twisting pitch of the unit is larger than the twisting pitch of the optical element.

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