JP2010139631A - Optical fiber cable - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical fiber cable which can be made thin in diameter and light in weight, and also can improve a workability during jacket removal and a routing property of cable by improving the structure of a tension member in a slotless type optical fiber cable. <P>SOLUTION: The optical fiber cable comprises: a coated optical fiber; a winding material spirally wound around the coated optical fiber; a tension member arranged in a manner surrounding the entirety of the coated optical fiber and the winding material; and a polyethylene jacket formed around the tension member. The tension member is composed of a high-strength polyethylene fiber and is fused into the polyethylene jacket by a part of the fiber being melted during the extrusion molding of the polyethylene jacket. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an optical fiber cable, and more particularly to a structure of a tension member provided in a slotless type optical fiber cable.

Conventionally, an optical fiber cable called a slotless type is known as compared with a slot type optical fiber cable in which optical fiber core wires are assembled in a groove type slot spacer. Since the slotless type optical fiber cable does not use a slot spacer, the diameter of the optical fiber cable can be reduced.
FIG. 12 is a cross-sectional view showing an example of a 24-core slotless optical fiber cable.
In the slotless optical fiber cable 10 shown in FIG. 12, six four-core optical fiber ribbons 101 are laminated and disposed at the center of the optical fiber cable 10. A buffer layer 102 made of PP yarn (polypropylene yarn) or the like is disposed around the optical fiber tape core wire 101. An outer sheath (sheath) 105 made of polyethylene or the like is formed on the outside by extrusion molding.

Further, two tension members (strength members) 103, 103 are embedded in the jacket 105 in the longitudinal direction of the optical fiber cable 10. The tension members 103 and 103 are provided in order to prevent an excessive stress from being applied to the optical fiber ribbon 101 due to tension or the like acting when laying the cable. Therefore, since the tension member 103 is required to have high resistance to tension, a metal such as a steel wire is generally used.
Further, two tear strings 104, 104 are embedded in the longitudinal direction of the optical fiber cable 10 along the buffer layer 102 in order to facilitate intermediate post-branching in the jacket 105.

In the slotless optical fiber cable 10 described above, the waterproof property is improved by using water-absorbing fibers for the buffer layer 102 (for example, Patent Document 1), or the same material can be obtained by using polyethylene fibers for the buffer layer 102. Considering addition of new functions such as making it easy to recycle by integrating with the outer casing (for example, Patent Document 2).
JP 2001-343567 A JP 2005-84355 A

However, in the conventional slotless optical fiber cable 10 shown in FIG. 12, the tension member 103 made of metal such as steel is an obstacle to reducing the weight of the optical fiber cable 10.
Further, since the two tension members 103 and 103 are generally arranged at symmetrical positions with respect to the center, the axis connecting the tension members 103 and 103 is necessarily the center of bending. As a result, the optical fiber cable 10 has a bending direction, which is a factor in reducing the cable handling.
Further, in the slotless type optical fiber cable 10, since the tear string 104 is taken out using a sharp tool when removing the jacket at the intermediate post-branch, there is a risk of accidentally disconnecting the optical fiber core wire. There is sex. Therefore, the outer cover removal work needs to be performed carefully and takes time.

  The present invention provides an optical fiber cable that can be reduced in diameter and weight by improving the structure of the tension member in the slotless type optical fiber cable, and can improve workability at the time of jacket removal and cable handling. The purpose is to do.

The present invention has been made to achieve the above object, and includes an optical fiber core wire,
A winding material spirally wound around the optical fiber core;
A tension member disposed so as to surround the entire optical fiber core and the winding material;
A polyethylene jacket formed around the tension member,
The tension member is made of high-strength polyethylene fiber, and a part of the tension member is melted at the time of extrusion molding of the polyethylene jacket, thereby being fused to the polyethylene jacket. is there.

  Preferably, the whole or part of the wrapping material is composed of water-absorbing fibers.

  More preferably, the fusion member between the tension member and the polyethylene jacket has a tear string fixed in the longitudinal direction along the inner surface of the polyethylene jacket.

  According to the present invention, in a slotless optical fiber cable, by improving the structure of the tension member, it is possible to reduce the diameter and weight, and to improve the workability at the time of removing the jacket and the cable handling ability. A cable is provided.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(First embodiment)
FIG. 1 is a sectional view of a 24-core slotless optical fiber cable according to the first embodiment, and FIG. 2 is an external side view of the optical fiber cable according to the first embodiment. In FIGS. 1 and 2, reference numerals shown in parentheses correspond to a third embodiment described later.
In the slotless type optical fiber cable 1 shown in FIGS. 1 and 2, six four-core optical fiber ribbons 11 are laminated in the center of the optical fiber cable 1. The four-fiber optical fiber ribbon is formed by arranging four optical fiber cores in a horizontal row and integrating them with a resin.

A wrapping material 12 is spirally wound around the optical fiber ribbon 11 to cover the entire optical fiber ribbon 11. The winding material 12 is composed of a plurality of (8 in FIG. 1) polypropylene fibers, and the polypropylene fibers are wound around the optical fiber ribbon 11 at a predetermined pitch. The polypropylene fiber is a fiber (string) obtained by twisting a plurality of polypropylene filaments (raw yarns), and includes, for example, a low heat shrink PP yarn.
By appropriately setting the configuration of the winding material 12 (for example, the fineness and number of polypropylene fibers, the winding pitch, etc.), it is possible to realize a desired pulling force (core pulling force) of the optical fiber core, and an optical fiber tape core. The protrusion of the line 11 can be effectively prevented.

A tension member 13 is formed around the winding material 12 so as to surround the whole. The tension member 13 is composed of a plurality (eight in FIG. 1) of high-strength polyethylene fibers, and the high-strength polyethylene fibers are arranged along the winding material 12 in a vertical orientation. The high-strength polyethylene fiber is a fiber obtained by twisting a plurality of high-strength polyethylene filaments (raw yarns) into one, for example, Dyneema (registered trademark) manufactured by Toyobo Co., Ltd. or Spectra (Honeywell) Registered trademark) and the like.
By appropriately setting the configuration of the tension member 13 (for example, the fineness and number of high-strength polyethylene fibers), a desired tensile force of the optical fiber cable can be realized.
For example, in order to obtain a good core wire pullout force to be described later, the fiber packing density may preferably be 2500 dtex / mm ² or more, more preferably set to 3500dtex / mm ² or more. Here, the fiber filling density means that in the cross section of the optical fiber cable 3, the fiber combined with the wrapping material and the tension member in the area obtained by subtracting the area occupied by the optical fiber ribbon from the area inside the jacket 15 occupies. It means area.

An outer sheath (sheath) 15 made of polyethylene is formed on the outside of the tension member 13 by extrusion molding. Due to the heat during extrusion of the outer jacket 15, a part of the outer peripheral side of the high-strength polyethylene fiber constituting the tension member 13 is melted and is in close contact with the outer jacket 15.
Further, two tear strings 14, 14 are embedded along the tension member 13 in the longitudinal direction of the optical fiber cable 1 in order to facilitate the intermediate rear branch in the outer jacket 15.

The preferable Example and evaluation result of the optical fiber cable 1 which concerns on 1st Embodiment are shown in FIG. Here, the tensile force at the time of 0.3% elongation, the presence / absence of adhesion of the optical fiber tape core 11 to the jacket 15 or the tension member (high-strength polyethylene fiber) 13, and the core wire pull-out force The characteristics are being evaluated.
The tensile force at 0.3% elongation is that the cable is placed in a straight line with no tension, the one end is fixed and the reverse end is gradually pulled, and the tension is 0.3% from the no tension state. It is obtained by measuring the load at the time.
Also, the core pull-out force is determined when the cable is placed on a straight line with no tension, one end of the cable is fixed, the optical fiber ribbon at the opposite end is pulled out at once, and the optical fiber ribbon begins to move. It can be obtained by measuring the tension.

Generally, the allowable elongation strain of an optical fiber when laying an optical fiber cable is set to 0.3% or less. In addition, when a person pulls and lays the optical fiber cable, a maximum tensile force of 294 N (= 30 kgf) is applied. Therefore, if the tensile force at 0.3% elongation is 294 N (= 30 kgf) or more, the resistance to tension is good.
If the optical fiber tape core wire 11 is fixed to the jacket 15 or the tension member 13, problems such as hindering the intermediate post-branching operation occur. Therefore, it is preferable that the optical fiber tape core wire 11 is not fixed.
The core wire pulling force f (N / 10 m) is evaluated as “×” when f <9.8, “◯” when 9.8 ≦ f <19.6, and “◎” when f ≧ 19.6. Is done. If the core pull-out force is 9.8 N / 10 m or more, the optical fiber cable in the cable will move in the longitudinal direction due to shrinkage due to temperature change, vibration due to wind pressure, etc., increasing loss or disconnection Since it is generally known that the problem of generating an error does not occur, this is used as an evaluation standard.

Example 1
As shown in FIG. 3, in the optical fiber cable 1 of Example 1, the optical fiber tape core wire 11 includes four single-mode optical fiber core wires (outer diameter: 0) coated with UV resin (primary coating). .25 mm) are arranged in a horizontal row, and six pieces of four-fiber optical fiber ribbons integrated with UV resin (secondary coating) are laminated. The dimension of the 4-core optical fiber ribbon is 1.1 (tape width) × 0.3 (tape thickness) mm.

  The winding material 12 is composed of four polypropylene fibers (fineness: 4444 dtex), and the polypropylene fibers are wound around the optical fiber tape core wire 11 by unidirectional twisting (pitch: 500 mm).

The tension member 13 is composed of five high-strength polyethylene fibers (fineness: 5333 dtex), and the high-strength polyethylene fibers are arranged around the winding material 12 in a vertical position.
The outer jacket 15 is made of polyethylene, and the dimensions excluding the outer peripheral convex portion indicating the burying position of the tear string 14 are thickness: 2 mm and outer diameter: 8 mm.

(Example 2)
As shown in FIG. 3, the optical fiber cable 1 of the second embodiment has a winding pitch of the winding material 12 of 200 mm (large overlap width) as compared with the first embodiment, and the tension member 13 is 8 in length. It differs in that it is composed of high-strength polyethylene fibers (fineness: 1760 dtex).

In the optical fiber cables 1 of Examples 1 and 2, the tensile forces at 0.3% elongation are 539N and 304N, respectively. From this, it can be said that the optical fiber cables 1 of Examples 1 and 2 have good resistance to tension.
There is no adhesion between the optical fiber tape core 11 and the jacket 15 or the tension member (high-strength polyethylene fiber layer) 13, and it can be said that the optical fiber tape core 11 is effectively restrained by the winding material 12.
Moreover, it can be said that the core wire drawing force is good, and the mounting density of the winding material 12 and the tension member 13 is appropriately controlled.

Thus, in the optical fiber cable 1 according to the first embodiment, the wrapping material 12 relaxes the external pressure to protect the optical fiber ribbon 11 and constrain the optical fiber ribbon 11 to restrain the optical fiber. It functions as a buffer layer that prevents the tape core wire 11 from jumping out and sticking to the jacket 15.
The tension member 13 functions as a buffer layer in the same manner as the wrapping material 12 and suppresses a tensile force so that a tension exceeding an allowable amount is not applied to the optical fiber ribbon 11. Since the tension member 13 is configured by vertically arranging high-strength polyethylene fibers, the cable will not be twisted when a tensile force is applied to the optical fiber cable 1.

According to the optical fiber cable 1 according to the first embodiment, the slotless structure can reduce the diameter of the optical fiber cable 1 and the tension member 13 has a small specific gravity compared to metal. Since it is comprised with the intensity | strength polyethylene fiber, the weight reduction of the optical fiber cable 1 can be achieved.
Since the tension member is not embedded in the outer jacket 15, the direction of bending is eliminated and the handling property is improved, and the outer jacket 15 can be made thinner, so that the diameter and weight can be reduced. Further, since the pipe cutter can be used for the jacket removal work, the workability is remarkably improved.
Since the wrapping material 12 is wound around the optical fiber ribbon 11, it is possible to prevent the optical fiber ribbon 11 from jumping out and sticking to the outer cover 15 or the fused portion of the tension member. . Further, by controlling the mounting density of the winding material 12 and the tension member 13, a predetermined core wire drawing force can be realized, and the core wire movement can be suppressed.

(Second Embodiment)
FIG. 4 is a cross-sectional view of a 24-core slotless optical fiber cable according to the second embodiment, and FIGS. 5 and 6 are external side views of the optical fiber cable according to the second embodiment. 4 to 6, the reference numerals shown in parentheses correspond to a fourth embodiment to be described later.
The optical fiber cable 2 according to the second embodiment is different from the optical fiber cable 1 according to the first embodiment in that the winding material 22 is formed of a fiber string. Since the configuration of the optical fiber ribbon 11, the tension member 13, the tear string 14, and the jacket 15 is the same as that of the first embodiment, the description thereof is omitted.

That is, in the optical fiber cable 2, one or two string-like winding members 22 are roughly wound around the optical fiber ribbon 11 at a predetermined pitch. In the case of single winding, the appearance shown in FIG. 5 is obtained, and in the case of two cross windings, the appearance shown in FIG. 6 is obtained. The winding material 22 is made of, for example, polypropylene fiber or polyester fiber.
By appropriately setting the configuration of the winding material 22 (for example, the fineness and number (1 or 2) of polypropylene fibers, winding pitch, etc.), the optical fiber tape core wire 11 can be effectively prevented from protruding.

  The preferable Example and evaluation result of the optical fiber cable 2 which concerns on 2nd Embodiment are shown in FIG. Evaluation items of the optical fiber cable 2 are the same as those in the first embodiment.

(Example 3)
As shown in FIG. 7, in the optical fiber cable 2 of Example 3, the structure of the optical fiber ribbon 11 is the same as that of Examples 1 and 2.
The winding material 22 is composed of a single polypropylene fiber (fineness: 4444 dtex), and the polypropylene fiber is roughly wound around the optical fiber tape core wire 11 by a one-way twist (pitch: 200 mm).

The tension member 13 is composed of eight high-strength polyethylene fibers (fineness: 5333 dtex), and the high-strength polyethylene fibers are arranged around the winding material 22 in a vertical position.
The outer jacket 15 is made of polyethylene, and the dimensions excluding the outer peripheral convex portion indicating the burying position of the tear string 14 are thickness: 2 mm and outer diameter: 8 mm.

Example 4
As shown in FIG. 7, the optical fiber cable 2 of Example 4 is different from Example 3 in that the winding material 22 is made of polyester fiber (fineness: 900 dtex), and the winding pitch of the winding material 22 is The difference is that it is 100 mm, and that the tension member 13 is composed of five pieces.

(Example 5)
As shown in FIG. 7, the optical fiber cable 2 of Example 5 is different from Example 4 in that the winding material 22 is composed of two polyester fibers (fineness: 222 dtex). The difference is that the winding pitch is 50 mm and the unidirectional twisting and cross winding are performed.

In the optical fiber cables 2 of Examples 3 to 5, the tensile forces at 0.3% elongation are 862N, 500N, and 490N, respectively. From this, it can be said that the optical fiber cables 2 of Examples 3 to 5 have good resistance to tension.
There is no adhesion between the optical fiber ribbon 11 and the jacket 15 or the tension member (high-strength polyethylene fiber layer) 13, and it can be said that the optical fiber ribbon 11 is effectively restrained by the winding material 22.
Moreover, it can be said that the core wire drawing force is good and the mounting density of the winding material 22 and the tension member 13 is appropriately controlled. In Examples 3 to 5, it is considered that the mounting density of the high-strength polyethylene fibers constituting the tension member 13 dominates the core wire drawing force.

  As described above, in the optical fiber cable 2 according to the second embodiment, the wrapping member 22 restrains the optical fiber tape core wire 11 so that the optical fiber tape core wire 11 protrudes outward and is fixed to the jacket 15. Can be prevented.

According to the optical fiber cable 2 according to the second embodiment, the configuration of the optical fiber cable 2 is simplified because the winding material 22 is composed of one or two fiber strings.
In addition, also in the optical fiber cable 2 which concerns on 2nd Embodiment, the effect similar to the optical fiber cable 1 which concerns on 1st Embodiment is acquired.

(Third embodiment)
The cross-sectional shape and appearance side surface of the optical fiber cable 3 according to the third embodiment are as shown in FIGS.
In the optical fiber cable 3 according to the third embodiment, the optical fiber cable 1 according to the first embodiment is configured in that a part or the whole of the wrapping material 32 is constituted by fibers having water absorption (water absorption fibers). And different. Since the configuration of the optical fiber ribbon 11, the tension member 13, the tear string 14, and the jacket 15 is the same as that of the first embodiment, the description thereof is omitted.

That is, in the optical fiber cable 3, the wrapping material 32 is spirally wound around the optical fiber ribbon 11 to cover the entire optical fiber ribbon 11. The winding material 32 is composed of a plurality of (8 in FIG. 1) water-absorbing fibers, and these water-absorbing fibers are wound around the optical fiber ribbon 11 at a predetermined pitch.
Note that the wrapping material 32 may be configured by alternately arranging water-absorbing fibers and non-water-absorbing fibers (for example, non-water-absorbing fibers such as polypropylene fibers).

As the water-absorbing fiber, those having an absorptivity of 8 times or more are preferable. For example, a plastic fiber coated with a water-absorbing powder or a fiber having water absorbency maintained can be used. There is Bel Oasis (registered trademark) manufactured by Teijin Fibers Limited.
The waterproof property of the optical fiber cable 3 can be improved by appropriately setting the configuration of the winding material 32 (for example, the fineness and number (ratio) of the water-absorbing / non-water-absorbing fibers, the winding pitch, etc.). In addition, a desired core drawing force can be realized, and the optical fiber tape core 11 can be effectively prevented from protruding.
For example, in order to obtain good waterproof properties, which will be described later, it is preferable that the packing density of the water-absorbing fibers is 500 dtex / mm ² or more. Here, the water-absorbing fiber filling density means the area occupied by water-absorbing fibers in the area obtained by subtracting the area occupied by the optical fiber ribbon from the area inside the jacket 15 in the cross section of the optical fiber cable 3. .

Here, the waterproof property is represented by a cable distance (water stoppage length: L) that has been submerged within a certain time when water is injected from a cut surface of a horizontally arranged cable. If it is 40 m or less, it is considered good.
In the case of an aerial optical fiber cable, closures are attached at intervals of a minimum of 40 m. When one closure is submerged, it may travel along the optical fiber cable and also enter the adjacent closure. If the water stop length is 40 m or less, it is possible to prevent water damage to a minimum, and this is regarded as an evaluation standard for waterproof properties.

The preferable Example and evaluation result of the optical fiber cable 3 which concerns on 3rd Embodiment are shown in FIG. The evaluation items of the optical fiber cable are substantially the same as those in Examples 1 to 5, and waterproof properties are added.
The evaluation of the waterproof property is “×” when the water stop length L (m)> 40, “◯” when 20 <L ≦ 40, and “◎” when f ≦ 20.

(Example 6)
As shown in FIG. 8, in the optical fiber cable 3 of Example 6, the structure of the optical fiber ribbon 11 is the same as that of Examples 1-5.
The wrapping material 32 is composed of four water-absorbing fibers (fineness: 3330 dtex), and the water-absorbing fibers are wound around the optical fiber ribbon 11 in a unidirectional twist (pitch: 500 mm).

The tension member 13 is composed of five high-strength polyethylene fibers (fineness: 5333 dtex), and the high-strength polyethylene fibers are arranged around the wrapping material 22 vertically.
The outer jacket 15 is made of polyethylene, and the dimensions excluding the outer peripheral convex portion indicating the burying position of the tear string 14 are thickness: 2 mm and outer diameter: 8 mm.

(Example 7)
As shown in FIG. 8, in the optical fiber cable 3 of Example 7, the winding material 32 has two polypropylene fibers (fineness: 4444 dtex) and two water-absorbing fibers (fineness: fineness) compared to Example 6. 3330 dtex) are alternately arranged, the winding pitch of the winding material 32 is 200 mm, and the tension member 13 is composed of eight high-strength polyethylene fibers (fineness: 1760 dtex). Is different.

In the optical fiber cables 2 of Examples 6 and 7, the tensile forces at 0.3% elongation are 529N and 294N, respectively. From this, it can be said that the optical fiber cables 3 of Examples 6 and 7 have good resistance to tension.
There is no adhesion between the optical fiber ribbon 11 and the jacket 15 or the tension member (high-strength polyethylene fiber layer) 13, and it can be said that the optical fiber ribbon 11 is effectively restrained by the winding material 32.
Moreover, it can be said that the core wire drawing force is good and the mounting density of the winding material 32 and the tension member 13 is appropriately controlled.

  Thus, in the optical fiber cable 3 according to the third embodiment, the wrapping material 32 exhibits a waterproof performance and functions as a buffer layer as in the first embodiment.

According to the optical fiber cable 3 according to the third embodiment, the waterproof property of the optical fiber cable 3 can be improved because a part or the whole of the wrapping material 32 is made of water-absorbing fibers.
In addition, also in the optical fiber cable 3 which concerns on 3rd Embodiment, the effect similar to the optical fiber cable 1 which concerns on 1st Embodiment is acquired.

(Fourth embodiment)
The cross-sectional shape and appearance side surface of the optical fiber cable 4 according to the fourth embodiment are as shown in FIGS.
The optical fiber cable 4 according to the fourth embodiment differs from the optical fiber cable 3 according to the third embodiment in that the winding material 42 is formed of a fiber string. The configurations of the optical fiber ribbon 11, the tension member 13, the tear string 14, and the jacket 15 are the same as those in the third embodiment, and thus the description thereof is omitted.

That is, in the optical fiber cable 4, one or two string-like winding materials (water-absorbing fibers) 42 are roughly wound around the optical fiber ribbon 11 at a predetermined pitch. In the case of single winding, the appearance shown in FIG. 5 is obtained, and in the case of two cross windings, the appearance shown in FIG. 6 is obtained.
In addition, as shown in FIG. 6, when it is set as the two winding materials 42, one is made into a water absorptive fiber and the other is comprised by the fiber (for example, non-water absorptive fibers, such as a polypropylene fiber) without water absorption. It may be.
The waterproof property of the optical fiber cable 4 can be improved by appropriately setting the configuration of the winding material 42 (for example, the fineness and number (1 or 2) of the water-absorbing fiber, the winding pitch, etc.). In addition, a desired core drawing force can be realized, and the optical fiber tape core 11 can be effectively prevented from protruding.

  The preferable Example and evaluation result of the optical fiber cable 4 which concern on 4th Embodiment are shown in FIG. Evaluation items of the optical fiber cable are the same as those in Examples 6 and 7.

(Example 8)
As shown in FIG. 9, in the optical fiber cable 4 of Example 8, the structure of the optical fiber ribbon 11 is the same as that of Examples 1-7.
The winding material 42 is composed of a single water-absorbing fiber (fineness: 5550 dtex), and this water-absorbing fiber is roughly wound around the optical fiber tape core wire 11 by a one-way twist (pitch: 200 mm).

The tension member 13 is composed of eight high-strength polyethylene fibers (fineness: 5333 dtex), and the high-strength polyethylene fibers are arranged vertically around the winding material 42.
The outer jacket 15 is made of polyethylene, and the dimensions excluding the outer peripheral convex portion indicating the burying position of the tear string 14 are thickness: 2 mm and outer diameter: 8 mm.

Example 9
As shown in FIG. 9, the optical fiber cable 4 of Example 9 is different from Example 8 in that the winding material 42 is composed of water-absorbing fibers (fineness: 3330 dtex), and two winding materials 42. Is different in that the winding pitch is 50 mm and unidirectional twisting and cross winding are used.

In the optical fiber cables 4 of Examples 8 and 9, the tensile forces at 0.3% elongation are 882N and 519N, respectively. From this, it can be said that the optical fiber cables 4 of Examples 8 and 9 have good resistance to tension.
There is no adhesion between the optical fiber ribbon 11 and the jacket 15 or the tension member (high-strength polyethylene fiber layer) 13, and it can be said that the optical fiber ribbon 11 is effectively restrained by the winding material 42.
In addition, the core wire pulling force is good in all cases, and it can be said that the mounting density of the winding material 42 and the tension member 13 is appropriately controlled. As in Examples 3 to 5, in Examples 8 and 9, the mounting density of the high-strength polyethylene fibers constituting the tension member 13 is considered to dominate the core wire drawing force.

  As described above, in the optical fiber cable 4 according to the fourth embodiment, the wrapping material 42 exhibits waterproof performance, and the optical fiber tape core wire 11 protrudes outward by restraining the optical fiber tape core wire 11. It is prevented from adhering to the jacket 15.

According to the optical fiber cable 4 according to the fourth embodiment, a part or the whole of the wrapping material 42 is made of water-absorbing fibers, so that the waterproof property of the optical fiber cable 4 can be improved.
In addition, also in the optical fiber cable 4 which concerns on 4th Embodiment, the effect similar to the optical fiber cable 2 which concerns on 2nd Embodiment is acquired.

As shown in Examples 1 to 9, a desired tensile resistance (tensile force of 30 kgf or more) can be realized by appropriately setting the configuration of the tension member 13 (for example, the fineness and number of high-strength polyethylene fibers).
Whether or not the optical fiber ribbon is fixed is considered to be related to the winding pitch of the winding materials 12, 22, 32, and the amount of fibers (fineness × number). In order to prevent sticking of the optical fiber ribbon, the winding pitch and the amount of fiber should be selected so that the optical fiber ribbons laminated with the winding materials 12, 22, 32, and 42 can be covered without any gaps. Is more preferable.

As mentioned above, although the invention made by this inventor was concretely demonstrated based on embodiment, this invention is not limited to the said embodiment, It can change in the range which does not deviate from the summary.
In the first to fourth embodiments, the two tear strings 14, 14 are provided in the longitudinal direction of the optical fiber cable 1 along the tension member 13 and are embedded in the jacket 15. 14 may be disposed in the tension member 13.

FIG. 10 is a cross-sectional view showing a modification of the 24-core slotless optical fiber cable according to the first embodiment, and FIG. 11 is an explanatory view showing a specific configuration of the optical fiber cable 5 according to the modification.
As shown in FIG. 10, in the optical fiber cable 5 according to the modified example, the tear strings 24, 24 are arranged in the longitudinal direction along the inner peripheral surface of the outer jacket 15 in the fused portion of the tension member 13 and the polyethylene outer jacket 15. It is fixed to.

In the first to fourth embodiments, the portion in which the tear strings 14 and 14 are embedded may be the starting point of the outer cover cracking due to the external force, and thus it is necessary to ensure a certain outer cover thickness. In the case of the modified example, since the jacket 15 can be made thinner, the optical fiber cable can be further reduced in diameter.
For example, in the example shown in FIG. 11, the thickness of the jacket 15 is reduced to 1.5 mm compared to the optical fiber cable 5 of Example 2 (see FIG. 3) having the same configuration except for the tear string. The outer diameter is reduced to 7 mm.
Further, by arranging the tear strings 24, 24 along the inner surface of the outer jacket 15, it is possible to improve the strength against the outer crack caused by an external force.

In the modification, the stripe pattern 16 indicating the position where the tear strings 24, 24 are embedded is formed on the outer peripheral surface of the outer cover 15, thereby replacing the convex portion formed on the outer cover 15.
Although FIG. 10 shows a modification of the first embodiment, the embedment position of the tear string can be similarly changed in the optical fiber cables 2 to 4 according to the second to fourth embodiments.
As shown in FIG. 11, the effects of the present invention are not impaired even in the configuration according to the modification.

  In the above embodiment, the optical fiber ribbon 11 may be a unit (for example, 8 cores × 3 units) in which a plurality of single optical fibers are bundled. Needless to say, the type of the optical fiber ribbon (4 cores, 8 cores, etc.) and the size of the optical fiber core (φ 0.25 mm, 0.5 mm, etc.) are not particularly limited.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

It is sectional drawing shown about an example of the optical fiber cable which concerns on 1st Embodiment. It is an external appearance side view shown about an example of the optical fiber cable concerning a 1st embodiment. It is explanatory drawing which shows the specific structure of the optical fiber cable which concerns on 1st Embodiment. It is sectional drawing shown about an example of the optical fiber cable which concerns on 2nd Embodiment. It is an external appearance side view shown about an example of the optical fiber cable which concerns on 2nd Embodiment. It is an external appearance side view shown about other examples of the optical fiber cable which concerns on 2nd Embodiment. It is explanatory drawing which shows the specific structure of the optical fiber cable which concerns on 2nd Embodiment. It is explanatory drawing which shows the specific structure of the optical fiber cable which concerns on 3rd Embodiment. It is explanatory drawing which shows the specific structure of the optical fiber cable which concerns on 4th Embodiment. It is sectional drawing which shows the modification of the optical fiber cable which concerns on 1st Embodiment. It is explanatory drawing which shows the specific structure of the optical fiber cable which concerns on a modification. It is sectional drawing shown about an example of the conventional optical fiber cable.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Optical fiber cable 11 Optical fiber tape core wire 12 Winding material 13 Tension member (strength body)
14 Tear string 15 Outer sheath (sheath)

Claims (3)

An optical fiber core,
A winding material spirally wound around the optical fiber core;
A tension member disposed so as to surround the entire optical fiber core and the winding material;
A polyethylene jacket formed around the tension member,
The optical fiber cable is characterized in that the tension member is made of high-strength polyethylene fiber, and a part of the tension member is melted at the time of extrusion molding of the polyethylene jacket, thereby being fused to the polyethylene jacket.   2. The optical fiber cable according to claim 1, wherein the whole or a part of the winding material is formed of a water-absorbing fiber.   3. The optical fiber cable according to claim 1, further comprising a tear string fixed in a longitudinal direction along an inner surface of the polyethylene jacket at a fusion portion between the tension member and the polyethylene jacket.

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