Patent Application
20230185049
The present application claims priority from Japanese Patent Application No. 2020-085734 filed in Japan on May 15, 2020, the contents of which are incorporated herein by reference in their entirety.
The present invention relates to an optical fiber cable.
An optical fiber cable includes a cable body, a tubular external sheath accommodating the cable body, a metallic reinforcing sheet provided between the cable body and the external sheath, and a ripcord disposed between the reinforcing sheet and the cable body (for example, see patent document 1). When the cable body is taken out from optical fiber cable, the cable body is taken out by tearing the reinforcing sheet and the external sheath with the ripcord.
Patent document 1: JP2017-72801A
However, in the optical fiber cable as described above, there is a gap between the cable body and the reinforcing sheet. Therefore, when the external sheath is torn with the ripcord, workability may be deteriorated because the ripcord is moved in the circumferential direction.
One or more embodiments may provide an optical fiber cable capable of improving workability by restraining the movement of the ripcord.
[1] An optical fiber cable comprises: a cable body that includes an optical fiber; an external sheath that accommodates the cable body; a protective layer that is disposed between the cable body and the external sheath; and a ripcord that is disposed between the cable body and the protective layer. The protective layer includes a groove that is formed on an inner circumferential surface of the protective layer and extends along an axial direction of the cable body. The ripcord is disposed in the groove.
[2] In one or more embodiments, the protective layer may have a corrugated shape that includes peaks and valleys alternately disposed along the axial direction of the cable body. The groove may include recesses that are formed by recessing a portion of the peaks. The recesses may be disposed along the axial direction of the cable body. The ripcord may be disposed in the recesses.
[3] In one or more embodiments, the ripcord may include a first ripcord and a second ripcord, the groove may include a first groove and a second groove, the first ripcord may be disposed in the first groove, and the second ripcord may be disposed in the second groove.
[4] In one or more embodiments, the optical fiber cable may satisfy a formula (1) below;
θ1≥120° (1)
in the formula (1), θ1 is an angle between a first straight line and a second straight line, the first straight line is a straight line that passes through a center of the cable body and a center of the first ripcord, and the second straight line is a straight line that passes through the center of the cable body and a center of the second ripcord.
[5] In one or more embodiments, the optical fiber cable may further comprise: at least a pair of tensile strength members embedded in the external sheath and facing each other across the cable body. The protective layer may include an overlapping portion formed by overlapping the both ends in a circumferential direction of the cable body, and the optical fiber cable may satisfy a formula (2) below;
θ2≤70° (2)
in the formula (2), θ2 is a larger angle of angles between a third straight line and a fourth straight line and an angle between the third straight line and a fifth straight line, the third straight line is a neutral line defined by the tensile strength members, the fourth straight line is a straight line that passes through a center of the cable body and a first end of the overlapping portion, and the fifth straight line is a straight line that passes through the center of the cable body and a second end of the overlapping portion.
[6] In one or more embodiments, the optical fiber cable may further comprise; a film that is attached to a inner surface of the protective layer to cover the tearing string. The ripcord may be disposed between the film and the groove.
[7] In one or more embodiments, the optical cable may satisfy a formula (3) below;
d
1
/D≥1/2 (3)
in the formula (3), d1 is a depth of the groove, and D is a diameter of the ripcord.
[8] In one or more embodiments, the protective layer may have a tubular shape around the cable body.
An optical fiber cable according to one or more embodiments can improve the workability by restraining the movement of the ripcord in the circumferential direction with the grooves formed on the inner surface of the protection layer.
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
As shown in
The cable body 10 in one or more embodiments comprises a optical fiber assembly 11, a press-wrapping tape 17, and an inner sheath 18.
The optical fiber assembly 11 is an assembly obtained by assembling a plurality of optical fibers 14. Specifically, in one or more embodiments, the optical fiber assembly 11 is formed by bundling a plurality of optical fiber units 12. Furthermore, as shown in
As shown in
As shown in
Then, as shown in
The configuration of the optical fiber ribbon 13 is not limited to the above. For example, the optical fiber 14 is not intermittently bonded, the entire optical fibers 14 may be bonded to each other. The configuration of the optical fiber unit 12 is not particularly limited to the above configuration. For example, the optical fiber units 12 may be formed only by bundling optical fibers 14 without using the optical fiber ribbons 13. The configuration of optical fiber assembly 11 is not particularly limited to the above-described configuration. For example, the optical fiber assembly 11 may be formed only by twisting optical fibers 14 without using the optical fiber units 12. Further, the optical fiber assembly 11 may be constituted by a loose tube accommodating the optical fibers.
The optical fiber ribbon is covered around by the press-wrapping tape 17. In one or more embodiments, the press-wrapping tape 17 is wound on the outer periphery of optical fiber assembly 11 in longitudinal direction so that the longitudinal direction of the press-wrapping tape 17 substantially coincides with the axial direction of the optical fiber cable 1 and the width direction of the press-wrapping tape 17 substantially coincides with the circumferential direction of the optical fiber cable 1. Since the winding method of the press-wrapping tape 17 is the longitudinal lapping, workability of the take-out operation of the optical fiber 14 from the optical fiber cable 1 is improved. The winding method of the press-wrapping tape 17 is not limited to the longitudinal lapping, for example, may be a spiral winding.
This press-wrapping tape 17 is made of a nonwoven fabric or a film. Specific examples of the nonwoven fabric constituting the press-wrapping tape 17 are not particularly limited, and a nonwoven fabric made of fibers such as polyester, polyethylene, and polypropylene is exemplified. Specific examples of the film constituting the press-wrapping tape 17 are not particularly limited, and a film made of a resin such as polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), or nylon is exemplified.
The inner sheath 18 is a tubular member covering the outer periphery of the press-wrapping tape 17, the optical fiber assembly 11 wrapped in the holding tape 17 is accommodated in the inner sheath 18. This inner sheath 18 is made of a resin material such as polyvinyl chloride (PVC), polyethylene (PE), nylon, ethylene fluoride, or polypropylene (PP)
The structure of cable body 10 is not particularly limited to the above, for example, may be a cable of a slot structure, a loose tube structure, or a slot-less structure. The outer shape of the cable body 10 is not particularly limited. For example, the outer shape of the cable body 10 may be round, flat, irregular, or irregular. Further, in one or more embodiments has exemplified a center tube structure comprising an inner sheath 18 is not particularly limited to the above, the inner sheath 18 may be omitted from an optical fiber assembly 11. That is, the cable body 10 may comprise at least one optical fiber.
A pair of the ripcords 20A, 20B is a string-shaped member for taking out the optical fiber 14 by tearing the protection layer 30 and the external sheath 40 at the middle portion of the optical fiber cable 1. The ripcords 20A, 20B are arranged to extend across the cable body 10 in substantially parallel. In the case a tensile strength member (tensile strength members 50A˜50D described below) is disposed in the external sheath 40, the ripcords are opposed to each other along a direction substantially perpendicular to the opposing direction of the tensile strength members 50A˜50D. In one or more embodiments, since the ripcords 20A, 20B do not overlap with the tensile strength member 50A˜50B, it is possible to further improve the tearing workability.
The ripcords 20A, 20B are not particularly limited to, but are made of, for example, a twisted yarn made of polyester, or a fiber string-like body such as aramid fiber or glass fiber. The outer diameter of the ripcords 20A, 20B may be, for example, 0.2 mm to 1.0 mm.
As shown in
As shown in the cross-sectional view of
As shown in
The first end 31 of the protection layer 30 overlaps the second end 32 of the protection layer 30 in the radial direction of the optical fiber cable 1, thereby an overlapping portion 33 of the protection layer 30 is formed. In this overlapping portion 33, the resin films 302, 303 are bonded to each other (thermally fused).
The overlapping portion 33 overlaps the tensile strength members 50A, 50B in the radial direction of the fiber-optic cable 1. On the other hand, the overlapping portion 33 does not overlap with the ripcords 20A, 20B. Thus, in one or more embodiments, since the overlapping portion 33 does not overlap with the ripcords 20A, 20B, it is possible to further improve the tearing workability.
As shown in
On the inner peripheral surface (the inner surface) 302a of the protection layer 30, grooves 36 having a linear shape and extending along the longitudinal direction of the optical fiber cable 1 is formed. As shown in
As shown in
The height h1 of the peak 34 of the protection layer 30 is not particularly limited, in view of the flexibility and the like of the optical fiber cable 1, it is preferable to 0.1 mm to 0.6 mm (0.1 mm≤h1≤0.6 mm). Here, the height h1 refers to the distance from the bottom of the valley 35 to the vertex of the peak 34.
The depth d1 of the recess 341 is not particularly limited, it is preferable to 0.10 mm to 0.34 mm (0.10 mm≤d1≤0.34 mm). By setting the depth d1 of the recess 341 within this range, the movement of the ripcord 20A (20B) can be restrained more reliably.
The ratio (d1/D) of the depth d1 of the recess 341 to the dimension D of the ripcord 20A (20B) is more preferably ⅙ or more (d1/D≥⅙), more preferably ½ or more (d1/D≥½), particularly preferably ⅔ or more (d1/D≥⅔). It is possible to further suppress the movement of the ripcord 20A (20B) in the circle, since the ratio of the recess 341 depth d1 to the dimension D (d1/D) is within any of the above ranges.
The above corrugated shaped protection layer 30 having the recess 341, for example, can be manufactured by roll forming. Specifically, in the processing roll, it can be manufactured by lowering the height of the peak of the portion corresponding to the recess 341.
In one or more embodiments, the recess 341 is formed in all of the peaks 34, the recesses 341 are continuously aligned in the longitudinal direction, but is not particularly limited thereto.
The recess 341 may be restrain to move the ripcord 20A (20B) and may need not be formed in all the peak 34. For example, the recesses 341 may be arranged intermittently in the longitudinal direction by recess 341 is formed only in a part of the peak 34. In this case, the groove 36 comprising at least one recess 341 will be intermittently aligned along the longitudinal direction. When the optical fiber cable 1 cut at a predetermined length is used, the distance between the recesses 341 can be set according to the length of the optical fiber cable after cutting. In this case, the interval between the recesses 341 may be set so that the recesses 341 are included in the optical fiber cable after cutting.
In one or more embodiments, the peaks 34 are formed independently each other, the valleys 35 are also formed independently each other, but is not limited thereto. For example, the peaks 34 may have interconnected spiral shapes, similarly, the valleys 35 may have interconnected spiral shapes.
Further, the protection layer 30 may not have a corrugated shape. For example, the protection layer 30 may have a tubular shape whose main surface is flat. Also in this case, a part of the protection layer is recessed, thereby the grooves extending along the longitudinal direction can be formed on the inner surface of the protection layer.
As shown in
Inside the external sheath 40, a plurality of (four in this example) tensile strength members (tension members) 50A to 50D are buried. The tensile strength members 50A to 50D are linear members extending in the longitudinal direction (refer to
The pair of the tensile strength members 50A, 50B faces each other across the cable body 10, and is arranged so as to be line-symmetrical with respect to the first straight line L1. On the other hand, the pair of the tensile strength members 50C, 50D is opposed across the cable body 10, and is arranged so as to be line-symmetrical with respect to the second straight line L2. Incidentally, the angle θ1 between the first straight line L1 and the second straight line L2 means the smaller angle of the angles between the first straight line L1 and the second straight line L2, the angle θ1 is 180° or less (θ1≤180°).
Further, the tensile strength member 50A is adjacent to the tensile strength member 50C along the circumferential direction of the external sheath 40, is arranged so as to be line-symmetrical with the tensile strength member 50C with respect to the third straight line L3. Similarly, the tensile strength member 50B is adjacent to the tensile strength member 50D along the circumferential direction of the external sheath 40, and is arranged to be line-symmetrical with the tensile strength member 50D with respect to the third linear L3.
As a material constituting the tensile strength members 50A to 50D, a non-metallic material or a metallic material can be exemplified. Specific examples of the non-metallic material are not particularly limited, and glass fiber reinforced plastic (GFRP), aramid fiber reinforced plastic (KFRP) reinforced by Kevlar®, polyethylene fiber reinforced plastic reinforced by polyethylene fibers, or fiber reinforced plastic (FRP) such as carbon fiber reinforced plastic (CFRP) reinforced by carbon fibers can be used. Specific examples of the metallic material, but is not particularly limited, for example, a metal wire such as a steel wire can be used.
Conventionally, when the external sheath is torn, the ripcords are moved in the circumferential direction, there is a case where workability is deteriorated. Conventionally, the ripcords also move in the manufacturing process of the optical fiber cable. Thereby, readjustment of the position of the ripcords is required, workability is deteriorated. In contrast, in one or more embodiments, since the protection layer 30 has grooves 36 and the ripcords 20A, 20B are disposed in grooves 36, it is possible to increase the contact area between the ripcords 20A, 20B and the protection layer 30. Therefore, the movement of the ripcords 20A, 20B in the circumferential direction is restrained, workability is improved.
Further, conventionally, when the optical fiber cable is short (for example, 10 m or less), since the pull-out force of the ripcord is weak, if not fixed at one end of the ripcords during the tearing operation, the ripcords may be pulled out from the optical fiber cable. In contrast, according to the optical fiber cable 1 of one or more embodiments, since the contact area between the protection layer 30 and the ripcords 20A, 20B are larger than the conventional, it is possible to increase the pull-out force of the ripcords 20A, 20B, the ripcords 20A, 20B are difficult to pull out from the optical fiber cable.
In one or more embodiments, as shown in
The above angle θ1 is not particularly limited, but is preferably 120° or more (θ1≥120°). The pair of the ripcords 20A, 20B are separated each other more than a certain distance in the circumferential direction of the optical fiber cable 1. Thus, since the width of the open portion of the protection layer 30 and the external sheath 40 is increased, it is possible to improve the taken-out workability of the cable body 10.
Here, the optical fiber cables having θ1 in the range shown in Table 1 below were produced, and the taken-out workability was evaluated. That is, the tearing protection layer 30 and the external sheath 40 was torn with a pair of the ripcords, and the cable body was taken out from the optical fiber cable. In this test, the taken-out workability of the cable body was evaluated in ∘ or ×. “∘” means that workability was good. “×” means that cable body could not be taken out. The results are given in Table 1.
From Table 1, by setting θ1 to 120° or more, it can be seen that the removal workability is good. The scope of this θ1 can also be applied in the second example described later.
The first end 33a of overlapping portion 33 preferably spaced from the ripcord 20A in the circumferential direction of the optical fiber cable 1, more specifically, the angle θ2 between the third straight line L3 and the fourth straight line L4 is preferably 70° or less (θ2≤70°). When θ2 is 70° or less (θ2≤70°), it is possible to further improve the tear workability.
The third straight line L3 is a neutral line defined by tensile strength members 50A to 50D, and the fourth straight line L4 is a straight line passing through the center C1 of the cable body 10 and the first end 33a of the overlapping portion 33. The neutral line, more specifically, in the transverse cross section of the optical fiber cable 1 is a straight line extending along the neutral plane. The neutral plane is a plane where elongation and shrinkage do not occur when the optical fiber cable 1 is bent in a direction substantially perpendicular to the opposing direction of the tensile strength members 50A to 50D.
In one or more embodiments, the neutral line is a straight line passing through the center point M1 between the center C4 of the tensile strength member 50A and the center C5 of the tensile strength member 50C, and the center point M2 between the center C6 of tensile strength member 50B and the center C7 of the tensile strength member 50D. In one or more embodiments, a neutral line is defined by two pairs of the tensile strength member 50A to 50D, but is not limited thereto. For example, if only a pair of the tensile strength members opposing each other across the cable body 10 is provided in the external sheath 40, a straight line passing through the center of each tensile strength member becomes a neutral line.
Here, the optical fiber cables having θ2 in the range shown in Table 2 below were produced, and the tearing workability was evaluated. In this test, the tearing workability of cable body was evaluated in ⊚, ∘, Δ, or ×. “⊚” means good workability. “∘” means that there was no problem in workability. “Δ” means that the workability became somewhat worse due to the time-consuming operation of tearing. “×” means that tearing could not be done. Table 2 shows the results.
As shown in table 2, in the case the angle θ2 between the third straight line L3 and the fourth straight line L4 is 70° or less, there is no problem in tear workability. In particular, in the case the angle θ2 is 50° or less, tear workability was good. The range of the angle θ2 can also be applied in the second example described later.
Similarly to the first end 33a, the second end 33b of the overlapping portion 33 is also preferably spaced from the ripcord 20B in the circumferential direction of the optical fiber cable 1, more specifically, the angle θ3 between the fifth straight line L5 and the fourth straight linear L4 is preferably 70° or less (θ3≤70°). Here, the fifth straight line L5 is a straight line passing through the center C1 of the cable body 10 and the second end 33b of the overlapping portion 33. In one or more embodiments, θ2 is larger than θ3 (θ2>θ3). The range of the angle θ3 can also be applied in the second example described later.
In the optical fiber cable 1B, the inclusion 60 is, for example, a fiber sheet having a tape shape extending longitudinally. In one or more embodiments, a plurality (eight in one or more embodiments) of inclusions 60 are disposed on the outer periphery of the inner sheath 18 of the cable body 10B. The inclusion 60 may be the longitudinally lapped, or it may be twisted by SZ twist or unidirectional twist. The material constituting the inclusion 60 is not particularly limited, but glass fibers, aramid fibers, carbon fibers, metal fibers, and the like can be used.
Thus, it is possible to improve the tensile force of the cable body 10 by disposing the inclusions 60 around the cable body 10. Thus, since the diameter of the tensile strength members 50A to 50D can be reduced, it is possible to reduce the diameter and weight of the optical fiber cable 1B.
Incidentally, it may be imparted with waterproofness to the inclusion 60. Further, although not shown in particular, it may be used a press-wrapping tape in place of the inclusions. Further, it may be provided with a press-wrapping tape on the outside of the inclusion 60. As the press-wrapping tape, it is possible to use the same as the press-wrapping tape 17. Further, it may be imparted with waterproofness to the press-wrapping tape. Further, an inclusion having a water absorbing property such as water absorbing yarn may be disposed between the inclusions 60.
Also in one or more embodiments, as in the first example, since the ripcords 20A, 20B are disposed on grooves 36 of the protection layer 30, the contact areas between the protection layer 30 and the ripcords 20A, 20B can be increased. Therefore, the movement of the ripcords 20A, 20B in the circumferential direction can be restrained, it is possible to improve the workability.
In the third example, the optical fiber cable 1C is different from the first example in that the optical fiber cable 1C further includes a resin film 70, other configurations are the same as those of the first example. Hereinafter, only the resin film 70 in the third example be described, and the same reference numerals are given to the same components as those in the first example, and description thereof will be omitted.
As shown in
In one or more embodiments, it is possible to further restrain the movement of the ripcords 20A, 20B in the circumferential direction by fixing the ripcords 20A, 20B to the grooves 36 with the resin film 70. Therefore, it is possible to further improve the workability.
In one or more embodiments, the resin film 70 is disposed on the entire inner periphery of the protection layer, but is not limited thereto. The resin film 70 may be disposed only on a part of an inner periphery of the protection layer 30 Specifically, for example, the resin film 70 may cover the ripcords 20A, 20B, may be attached only to a portion located in the vicinity of the ripcords 20A, 20B of the protection layer 30.
Embodiments heretofore explained are described to facilitate understanding of the present invention and are not described to limit the present invention. It is therefore intended that the elements disclosed in the above embodiments include all design changes and equivalents to fall within the technical scope of the present invention.
1, 1B, 1C . . . Optical fiber cable
10, 10B . . . Cable body
11 . . . Optical fiber assembly
17 . . . Press-wrapping tape
18 . . . Inner sheath
20A, 20B . . . Ripcords
30 . . . Protection layer
40 . . . External sheath
41 . . . Gap
50A to 50D . . . Tensile strength member
60 . . . Inclusion
70 . . . Resin film
| Number | Date | Country | Kind |
|---|---|---|---|
| 2020-085734 | May 2020 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2021/005686 | 2/16/2021 | WO |
