JP5778723B2 - Fiber optic cable - Google Patents

Description

  The present invention relates to an optical fiber cable in which an optical fiber core wire is covered with a jacket.

  The FTTH (Fiber To The Home) service, which provides a high-speed communication service by directly connecting a telecommunications carrier and a subscriber's home with an optical fiber, has become widespread. The optical fiber cable generally has a structure in which an optical fiber core and a tensile body are covered with a jacket made of a thermoplastic resin.

  When drawing an optical fiber cable connected to a telecommunications carrier and routed to the vicinity of the subscriber's house to the subscriber's house, the outer cover is partially removed by cutting the outer cover at the intermediate portion of the optical fiber cable, An intermediate post-branching operation for taking out the optical fiber core wire is required.

  By the way, an event occurs in which the bearfish punctures the laying tube into the optical fiber cable, and the optical fiber core wire is bent or disconnected. The optical fiber cable is required to have a good workability in which the jacket can be divided and the optical fiber core wire can be easily taken out, while it can prevent a malfunction caused by the burrowing of the oat tube. Seminess is required.

JP 2012-145760 A JP2012-118450A

  In Patent Document 1, the yield point strength of the material forming the jacket is defined within a predetermined range, and the shortest distance between the surface of the optical fiber core and the surface of the jacket is expressed by a relational expression including the yield point strength. It is described that it stipulates. By satisfying the relationship between the yield point strength range described in Patent Document 1 and the shortest distance between the surface of the optical fiber core and the surface of the jacket, good workability and resistance to taking out the optical fiber core are obtained. Semi-satisfaction can be achieved.

  As a structure different from the optical fiber cable described in Patent Document 1, there is a structure described in Patent Document 2. Patent Document 2 discloses a structure in which a tensile body is coated with a resin to form a tensile body coated body, the optical fiber core wire is sandwiched between the tensile body coated bodies, and the entire optical fiber core wire and the tensile body coated body are coated with a jacket. An optical fiber cable is described.

  The optical fiber cable described in Patent Document 2 is also required to satisfy both good workability for taking out the optical fiber core and semi-resistance. However, in the optical fiber cable described in Patent Document 2, the structure of the optical fiber cable is different from the structure of the optical fiber cable described in Patent Document 1. It has been found that even if the shortest distance from the surface is defined by the relational expression described in Patent Document 1, the semi-resistance cannot be satisfied.

  Therefore, the present invention has a structure in which the optical fiber core wire is sandwiched between the tensile strength coating bodies, and the entire optical fiber core wire and the tensile strength coating body are covered with an outer sheath, and has good workability for taking out the optical fiber core wire. An object of the present invention is to provide an optical fiber cable capable of achieving both semi-resistance.

In order to solve the above-mentioned problems of the prior art, the present invention is arranged to sandwich an optical fiber core wire and the optical fiber core wire from a first direction, and the tensile body is covered with a coating. A body, and a jacket covering the whole of the optical fiber core wire and the tensile body covering body,
The material forming the jacket has a yield strength σy of the following formula (1)
10 MPa ≦ σy ≦ 26 MPa (1)
The filling,
Of the surface near the optical fiber core in the surface facing the optical fiber core in the tensile strength covering, the outer cover of the surface in the second direction orthogonal to the first direction The shortest distance z between the nearest position closest to the surface and the surface of the jacket is expressed by the following formula (2)
z ≧ 156.2σy ^−2.06 (2)
An optical fiber cable is provided.

  In the above configuration, the outer cover has a notch formed in the width in the first direction of the strength member covering, and the shortest distance z between the nearest position and the notch is expressed by Equation (2). It is preferable to satisfy.

  According to the optical fiber cable of the present invention, even if the structure is such that the optical fiber core wire is sandwiched between the tension member coverings that are not bonded or fused to the jacket, it has good workability and resistance to taking out the optical fiber core wire. Semi-satisfaction can be achieved.

It is sectional drawing which shows the optical fiber cable of 1st Embodiment. It is an expanded partial sectional view of the optical fiber cable of a 1st embodiment. It is sectional drawing which shows the optical fiber cable of 2nd Embodiment. It is an expanded partial sectional view of the optical fiber cable of a 2nd embodiment. It is an expanded partial sectional view which shows the modification of the optical fiber cable of 1st Embodiment.

  At least the following matters will be apparent from the description and drawings described below.

An optical fiber core, a tensile body covering body that is disposed so as to sandwich the optical fiber core wire from the first direction and is coated with a tensile body, and the optical fiber core line and the tensile body covering body. With a jacket covering the whole,
The material forming the jacket has a yield strength σy of the following formula (1)
10 MPa ≦ σy ≦ 26 MPa (1)
The filling,
The closest position of the surface in the second direction orthogonal to the first direction among the surfaces facing the optical fiber core wire in the tensile body covering, closest to the surface of the jacket, The shortest distance z to the surface of the
z ≧ 156.2σy− ^2.06 (2)
An optical fiber cable characterized by satisfying the above becomes clear.

  With such an optical fiber cable, even if the structure is such that the optical fiber core wire is sandwiched between tensile strength sheaths that are not bonded or fused to the jacket, good workability and resistance to taking out the optical fiber core wire can be obtained. Semi-satisfaction can be achieved.

  In the above optical fiber cable, a notch is formed in the jacket in the width in the first direction of the strength member covering, and the shortest distance z between the nearest position and the notch is expressed by the formula (2). ) Is preferably satisfied.

  Thereby, the cutting and splitting of the jacket can be further facilitated, and even if the structure is such that the optical fiber core wire is sandwiched between the tension member coverings that are not bonded or fused to the jacket, It is possible to achieve both good workability and semi-resistance.

  Hereinafter, the optical fiber cable of each embodiment will be described with reference to the accompanying drawings. In each embodiment, substantially the same parts are denoted by the same reference numerals, and description of common parts is omitted as appropriate.

<First Embodiment>
FIG. 1 is a cross-sectional view of the optical fiber cable 101 according to the first embodiment cut in a direction perpendicular to the longitudinal direction. As shown in FIG. 1, an optical fiber cable 101 includes an optical fiber core wire 10 sandwiched between a pair of strength member coverings 40 in which a strength member 20 is covered with a covering 30 made of a thermoplastic resin. And the tensile strength covering 40 are covered with a jacket 50 made of a thermoplastic resin.

  The optical fiber core wire 10 may be one or more optical fiber strands, or may be one or more tape core wires. In the case of a tape core, it may be an intermittently fixed tape core. The configuration of the optical fiber core wire 10 is arbitrary. The strength member 20 is formed of, for example, a steel wire or an aramid fiber.

  The covering 30 and the jacket 50 are made of polyethylene, for example. The covering 30 and the jacket 50 are preferably formed of linear low density polyethylene (LLDPE) or high density polyethylene (HDPE).

  It is preferable that the tensile strength covering 40 and the outer jacket 50 are not fixed (adhered or fused). For example, by setting the melting point of the material forming the jacket 50 as the first melting point and setting the melting point of the material forming the covering 30 as the second melting point higher than the first melting point, It can be set as the state which the jacket 50 does not mutually adhere.

  In order to improve the workability of cutting and dividing the jacket 50 and taking out the optical fiber core 10 from the optical fiber cable 101, the yield point strength σy of the material forming the jacket 50 is 26 MPa or less. It is preferable. In order to ensure semi-resistance, the yield point strength σy is preferably 10 MPa or more. That is, the material forming the outer cover 50 satisfies the formula (1).

  10 MPa ≦ σy ≦ 26 MPa (1)

  Since the grounds that it is preferable to satisfy Expression (1) are described in detail in Patent Document 1, detailed description thereof is omitted here.

  In FIG. 1, the shortest distance between the surface of the optical fiber core wire 10 and the surface of the jacket 50 is a distance indicated by y. Patent Document 1 describes that if the shortest distance y satisfies the formula (3), the semi-resistance can be satisfied.

y ≧ 156.2σy− ^2.06 (3)

  However, in the optical fiber cable having the configuration described in Patent Document 1, the semi-resistance can be satisfied if Expression (3) is satisfied. However, in the optical fiber cable 101 configured as shown in FIG. Even if the shortest distance y satisfies the formula (3), it has become clear that the semi-resistance cannot be satisfied.

  The reason will be explained. If the strength member covering 40 and the jacket 50 are not fixed to each other, a boundary exists between the strength member covering 40 and the jacket 50. This is the same as long as the tensile strength covering 40 and the jacket 50 are slightly fused.

  As shown by an arrow A <b> 1 in FIG. 1, if the bearfish pierces the egg-laying tube at the boundary between the strength member covering body 40 and the jacket 50, the egg-laying tube may reach the optical fiber core wire 10. Then, the optical fiber core wire 10 is bent to cause a problem that the loss increases or is disconnected.

  Therefore, the optical fiber cable 101 of the first embodiment is configured as follows in order to satisfy the semi-resistance. As shown in the enlarged view of FIG. 2, a position closest to the surface of the outer jacket 50 at the boundary between the tension member covering body 40 and the outer jacket 50 is defined as a nearest position Pz. The shortest distance between the nearest position Pz and the surface of the outer jacket 50 is a distance indicated by z. If the shortest distance z satisfies the formula (2), the semi-resistance can be satisfied.

z ≧ 156.2σy− ^2.06 (2)

  As described above, in the optical fiber cable 101 according to the first embodiment, the material forming the outer cover 50 satisfies the formula (1), and the outer cover 50 at the boundary between the tensile strength covering body 40 and the outer cover 50 is used. The shortest distance z between the closest position Pz that is the position closest to the surface of the outer surface and the surface of the outer cover 50 satisfies the formula (2). By satisfy | filling Formula (1) and Formula (2), the favorable workability | operativity which takes out the optical fiber core wire 10, and semi-resistance can be made compatible.

Second Embodiment
FIG. 3 is a cross-sectional view of the optical fiber cable 102 of the second embodiment cut in a direction perpendicular to the longitudinal direction. As shown in FIG. 3, a notch 50 n having a V-shaped cross section is formed on the surface of the jacket 50 to facilitate the cutting and dividing of the jacket 50 and to easily take out the optical fiber core wire 10. The notches 50n are formed on both sides in the vertical direction in FIG. Other configurations are the same as those of the optical fiber cable 101 of the first embodiment.

  When the notch 50n is formed, as shown in FIG. 4, it is necessary that the shortest distance z between the nearest position Pz and the notch 50n satisfies the formula (2). If the notch 50n is formed at a position shifted in the left direction closer to the optical fiber core wire 10 than the position shown in FIG. 4 within the width of the tensile strength covering 40, the nearest position described in FIG. Even if the shortest distance z between Pz and the surface of the jacket 50 satisfies the formula (2), the semi-resistance cannot be satisfied between the point Pz and the notch 50n.

  In the optical fiber cable 102 of the second embodiment, both the shortest distance z between the nearest position Pz and the surface of the jacket 50 and the shortest distance z between the nearest position Pz and the notch 50n satisfy Expression (2). By forming the notch 50n, it is possible to cut and divide the jacket 50 more easily than the optical fiber cable 101 of the first embodiment. And also in the structure in which the notch 50n is formed, it is possible to achieve both good workability for taking out the optical fiber core wire 10 and semi-resistance.

  The notch 50n may be provided at a position where the shortest distance z between the nearest position Pz and the notch 50n satisfies the formula (2) within the width of the tensile strength covering 40.

<Modification>
FIG. 5 shows a modification of the optical fiber cable 101 of the first embodiment. In FIG. 1, the tensile strength body 20 is covered with a covering 30 so as to have a square or rectangular cross section, thereby forming a tensile body covering body 40 having a square or rectangular cross section. Therefore, the end closest to the surface of the outer jacket 50 among the surfaces of the tensile body covering 40 facing the optical fiber core wire 10 is set as the nearest position Pz.

  5 is orthogonal to the direction (second direction) orthogonal to the direction (first direction) connecting the two strength members 20 on the surface facing the optical fiber core wire 10. The surface 40a and inclined surfaces 40b and 40c inclined with respect to the orthogonal surface 40a are formed.

  In such a case, of the orthogonal surfaces 40a, the end of the orthogonal surface 40a that is the closest to the surface of the jacket 50 is defined as the nearest position Pz, and the shortest distance z between the nearest position Pz and the surface of the jacket 50 is expressed by the equation What is necessary is just to comprise so that (2) may be satisfy | filled.

  The same applies to the case where the surface of the tensile strength covering 40 facing the optical fiber core wire 10 is a curved surface convex toward the optical fiber core wire 10 side. Of the curved surface, the position closest to the surface of the outer cover 50 in the portion along the second direction is the closest position Pz, and the shortest distance z between the closest position Pz and the surface of the outer cover 50 satisfies the formula (2). What is necessary is just to comprise.

  Although not particularly illustrated, the same applies to the case where the strength member covering body 40 is configured as shown in FIG.

  As described above, when the entire surface of the strength member covering body 40 on the side facing the optical fiber core wire 10 is the surface in the second direction, the end of the surface on the facing side is set as the nearest position Pz. That's fine. In addition, when a part of the surface of the strength member covering body 40 facing the optical fiber core wire 10 is a surface in the second direction, the end of the portion that is the surface in the second direction is What is necessary is just to set it as the latest position Pz.

  In the above description, only the shortest distance z between the nearest position Pz located on the upper side of the tensile strength covering 40 disposed on the right side in FIGS. 1 and 3 and the surface of the outer jacket 50 (or the notch 50n) is mentioned. . Similarly, the nearest position Pz located on the lower side of the tensile strength covering 40 arranged on the right side and the nearest positions Pz located on the upper side and the lower side of the tensile strength covering 40 arranged on the left side are also the nearest positions. Naturally, the shortest distance z between Pz and the surface of the jacket 50 (or the notch 50n) needs to satisfy the formula (2).

  The present invention is not limited to the embodiments described above, and various modifications can be made without departing from the scope of the present invention. In each embodiment, the strength member 20 is individually covered with the covering 30 to form a pair of strength member coverings 40. However, the pair of strength member coverings 40 are connected in one of the second directions to be integrated. It is good also as a typical tension body covering.

  Further, the optical fiber cables 101 and 102 may be optical fiber cables having a self-supporting structure in which support lines are arranged in the jacket 50.

DESCRIPTION OF SYMBOLS 10 Optical fiber core wire 20 Strength member 30 Cover 40 Strength member cover 50 Outer sheath 50n Notch 101, 102 Optical fiber cable

Claims (2)

An optical fiber core,
A tensile body covering body that is disposed so as to sandwich the optical fiber core wire from the first direction, and the tensile body is covered with a covering;
A jacket covering the whole of the optical fiber core wire and the tensile body covering;
With
The material forming the jacket has a yield strength σy of the following formula (1)
10 MPa ≦ σy ≦ 26 MPa (1)
The filling,
Of the surface near the optical fiber core in the surface facing the optical fiber core in the tensile strength covering, the outer cover of the surface in the second direction orthogonal to the first direction The shortest distance z between the nearest position closest to the surface and the surface of the jacket is expressed by the following formula (2)
z ≧ 156.2σy ^−2.06 (2)
An optical fiber cable characterized by satisfying The outer cover has a notch formed in the width in the first direction of the strength member covering,
The optical fiber cable according to claim 1, wherein the shortest distance z between the nearest position and the notch satisfies the formula (2).

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