JP2016075814A - Optical fiber cable - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical fiber cable capable of densely housing optical fibers while maintaining satisfactory waterproof performance.SOLUTION: An optical fiber cable includes: a slot 11 in which housing grooves 21 are formed in an axial direction; a plurality of optical fibers 33 that are housed in the housing grooves 21; a water absorption tape 13 that is formed such that water absorbing powder is adhered to a base fabric, and wound around the slot 11; and a sheath 14 that covers a periphery of the slot 11 via the water absorption tape 13. Assuming that a groove width of the housing grooves 21 at an outer periphery of the slot 11 is defined as W, a groove depth of the housing grooves 21 in a radial direction of the slot 11 is defined as D, an area of the housing grooves 21 in a cross section orthogonal to the axial direction of the slot 11 is defined as S1, and a total sectional area of the optical fibers 33 housed in the housing grooves 21 is defined as S2, the optical fiber cable is configured to satisfy S2/S1≤0.6 and S2/S1≤0.2(W/D)+0.3.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an optical fiber cable containing a plurality of optical fibers.

  2. Description of the Related Art Conventionally, there is an optical fiber cable having a structure in which a plurality of partition walls extending in the radial direction toward the cable jacket and extending over the entire length of the cable are formed in the cross section of the cable. In this optical fiber cable, a plurality of optical fiber core wires that are twisted together or gathered straight are arranged between partition walls to form a cable core (see Patent Document 1).

JP2013-142853A

For optical fiber cables, for example, by winding a water-absorbing tape with water-absorbing powder made of a highly water-absorbing resin on the base fabric, the water-absorbing powder swells during water so that it fills the gaps and prevents water from spreading. Is done.
However, in the optical fiber cable of Patent Document 1 in which the optical fiber core wires are packed at a high density between the partition walls, it is difficult for the water absorption powder of the water absorption tape to enter the bottom between the partition walls. For this reason, in this optical fiber cable, water that has entered between the partition walls penetrates into the interior and is transmitted in the axial direction of the cable.

  An object of this invention is to provide the optical fiber cable which can accommodate an optical fiber in high density, maintaining favorable waterproof performance.

The optical fiber cable according to the present invention is
A slot in which a receiving groove is formed in the axial direction;
A plurality of optical fibers housed in the housing grooves;
Water absorbent powder is attached to the base fabric, and the water absorbent tape wound around the slot;
A jacket covering the periphery of the slot via the water absorbing tape;
Have
The groove width of the housing groove on the outer peripheral side of the slot is W, the groove depth of the housing groove along the radial direction of the slot is D, the cross-sectional area of the housing groove orthogonal to the axial direction of the slot is S1, When the total cross-sectional area of the optical fiber accommodated in the accommodation groove is S2,
S2 / S1 ≦ 0.6 and S2 / S1 ≦ 0.2 (W / D) +0.3
It is configured to satisfy.

  ADVANTAGE OF THE INVENTION According to this invention, the optical fiber cable which can accommodate an optical fiber in high density can be provided, maintaining favorable waterproof performance.

It is sectional drawing of the optical fiber cable which concerns on this embodiment. It is sectional drawing in one accommodation groove | channel of an optical fiber cable. It is sectional drawing of the intermittent connection type | mold optical tape core wire accommodated in the accommodation groove | channel. It is a schematic side view of the test location explaining a waterproof test. It is a graph which shows a waterproof test result. It is sectional drawing of the optical fiber cable of a modification. It is a partial expanded sectional view of one accommodation groove in the optical fiber cable of a modification. It is sectional drawing of a subunit. (A) It is sectional drawing of the intermittent optical tape core wire of the state gathered together in the bundle form, (b) It is a top view of the intermittent optical tape core wire before gathering together in the bundle form. (A) It is a perspective view of a subunit, (b) It is a perspective view of an optical fiber unit.

<Outline of Embodiment of the Present Invention>
First, an outline of an embodiment of the present invention will be described.
One embodiment of the optical fiber cable according to the present invention is:
(1) a slot in which the housing groove is formed in the axial direction;
A plurality of optical fibers housed in the housing grooves;
Water absorbent powder is attached to the base fabric, and water absorbent tape wound around the slot;
A jacket covering the periphery of the slot via the water absorbing tape;
Have
The groove width of the housing groove on the outer peripheral side of the slot is W, the groove depth of the housing groove along the radial direction of the slot is D, the cross-sectional area of the housing groove orthogonal to the axial direction of the slot is S1, When the total cross-sectional area of the optical fiber accommodated in the accommodation groove is S2,
S2 / S1 ≦ 0.6 and S2 / S1 ≦ 0.2 (W / D) +0.3
It is configured to satisfy.
According to the configuration of (1), the water-absorbing powder adhering to the water-absorbing tape can be uniformly introduced into the housing groove and can reach the bottom of the housing groove. Thereby, even if water permeates into the housing groove, the water-absorbing powder swells and the inside of the housing groove is reliably closed by the swollen water-absorbing powder. Therefore, the water that has entered the housing groove is prevented from being transmitted in the axial direction, and the spread of the water is prevented. Thereby, it is possible to provide an optical fiber cable in which optical fibers are accommodated at a high density while maintaining good waterproof performance.

(2) In the housing groove, a plurality of optical fibers are arranged in parallel, and an intermittent optical tape core wire in which the width directions of adjacent optical fibers are intermittently connected in the longitudinal direction is housed. It may be.
(2) According to this configuration, the optical fiber can be easily accommodated at a high density by accommodating the intermittent optical tape core in the accommodation groove. Thereby, a high-density optical fiber cable having good waterproof performance can be easily provided.

(3) A plurality of optical tape cores in which a plurality of the optical fibers are arranged in parallel are integrated in the housing groove, and ends in the width direction of the adjacent optical tape cores are arranged in parallel. An intermittently connected optical tape core that is intermittently connected in the longitudinal direction may be accommodated.
According to the structure of (3), an optical fiber can be easily accommodated in high density by accommodating an intermittent connection type optical tape core wire in an accommodation groove. Thereby, a high-density optical fiber cable having good waterproof performance can be easily provided.

(4) The slot may have a bending rigidity of 1000 MPa or more.
According to the configuration of (4), since the strength of the slot is increased, sufficient strength can be ensured even if the cross-sectional area of the slot is reduced. As a result, the number of optical fibers accommodated can be increased by increasing the accommodating grooves without increasing the weight while reducing the diameter, and the density can be further increased.

<Details of Embodiment of the Present Invention>
Hereinafter, an example of an embodiment of an optical fiber cable according to the present invention will be described with reference to the drawings. In addition, this invention is not limited to these illustrations, is shown by the claim, and intends that all the changes within the meaning and range equivalent to a claim are included.

FIG. 1 is a cross-sectional view of an optical fiber cable 10 according to the present embodiment.
As shown in FIG. 1, the optical fiber cable 10 according to the present embodiment includes a slot 11, an intermittently connected optical tape core wire 12, a water absorbing tape 13, and a jacket 14. The optical fiber cable 10 has an outer diameter of, for example, about 24 mm.

  The slot 11 is formed of a hard resin material such as synthetic resin of polycarbonate (PC) and polybutylene terephthalate (PBT) or high-density polyethylene (HDPE). As a result, the slot 11 has a bending rigidity of 1000 MPa or more. The slot 11 has an outer diameter of about 20 mm, for example. A tension member 22 such as a steel wire is embedded in the center of the slot 11. The slot 11 is formed with a plurality of spiral grooves or SZ-shaped (in this example, five) receiving grooves 21.

  The water absorbing tape 13 is wound around the slot 11 by, for example, vertical attachment or horizontal winding. The water-absorbing tape 13 is obtained by adhering water-absorbing powder to a base fabric made of polyester or the like, for example. The water-absorbing powder is a highly water-absorbing resin that swells by adsorbing water, and examples of the highly water-absorbing resin include starch and polyacrylic acid. In the optical fiber cable 10, the water-absorbing powder falls off the base cloth and enters the housing groove 21 by winding the water-absorbing tape 13 to which the water-absorbing powder made of the highly water-absorbing resin is attached around the slot 11.

  The outer cover 14 is made of, for example, a resin such as polyethylene (PE), and the resin is extruded from the slot 11 around which the water-absorbing tape 13 is wound. It is formed to cover the surroundings.

FIG. 2 is a cross-sectional view of one receiving groove 21 of the optical fiber cable 10.
As shown in FIGS. 1 and 2, the receiving grooves 21 are open on the outer peripheral side of the slot 11 and are formed at equal intervals in the circumferential direction of the slot 11.

  In the housing groove 21, both side wall portions 21 a are gradually approached from the outer peripheral side of the slot 11 toward the center portion side. The receiving groove 21 has a curved surface with a bottom 21 b that curves toward the center of the slot 11. A plurality (five in this example) of intermittently connected optical tape cores 12 are accommodated in the accommodating groove 21.

FIG. 3 is a cross-sectional view of the intermittently connected optical tape core 12 housed in the housing groove 21.
The intermittently connected optical tape core 12 is obtained by arranging optical tape cores 31 in a planar shape and intermittently connecting adjacent optical tape cores 31 with a connecting resin 32 in the longitudinal direction. The optical tape core wire 31 is composed of a plurality of optical fibers 33. The optical fiber 33 is obtained by coating the periphery of a glass fiber composed of a core and a clad with a resin. The optical tape core 31 is formed by arranging a plurality of optical fibers 33 in parallel and integrating them with a resin. The optical tape core wire 31 may be intermittently connected in the longitudinal direction. The intermittently connected optical tape core 12 is accommodated in the accommodating groove 21 in a form rolled up with the connection side by the connection resin 32 inside. The intermittently connected optical tape core 12 may be accommodated in the accommodating groove 21 in a form that is rounded with the connection side by the connection resin 32 facing outward.

  In this example, the intermittently connected optical tape core 12 is configured by connecting ten optical tape cores 31, and the optical tape core 31 is configured by four optical fibers 33. That is, in each of the five receiving grooves 21 (see FIG. 1) of the slot 11, five 40-fiber intermittently connected optical tape cores 12 having 40 optical fibers 33 are housed. Therefore, the optical fiber cable 10 of this example is a high-density multi-core optical fiber cable including a total of 1000 optical fibers 33.

  The intermittently connected optical tape cores 12 housed in the housing grooves 21 are different from each other in the color of the connecting resin 32. Thus, when the intermittently connected optical tape core 12 is taken out from each housing groove 21, the desired intermittently connected optical tape 12 can be identified and extracted by the color of the connecting resin 32.

  In the above-described optical fiber cable 10 of this example, the water-absorbing powder of the water-absorbing tape 13 falls off from the base fabric and enters the gap in the housing groove 21. Further, the water-absorbing powder is formed between the intermittently connected optical tape core 12 and the side walls 21a of the receiving groove 21, between the intermittently connected optical tape core 12 and the bottom 21b of the receiving groove 21, and intermittently connected light. It enters between the tape cores 12. This water-absorbing powder is more likely to reach the bottom 21b when the groove width W of the housing groove 21 is larger and the groove depth D of the housing groove 21 is smaller.

  However, when the optical fibers 33 are housed in the housing grooves 21 at a high density, the water absorbent powder of the water absorbent tape 13 that has fallen off from the base fabric is less likely to enter the gaps in the housing grooves 21. In particular, it becomes difficult for the water-absorbing powder to enter between the intermittently connected optical tape core 12 and the bottom 21 b of the housing groove 21. In such a state, for example, when water enters the receiving groove 21, even if the water-absorbing powder in the receiving groove 21 swells, the gap in the receiving groove 21 is not completely filled, and the intruded water does not fill the optical fiber cable. There is a risk of flooding spreading in the axial direction. For this reason, in order to spread the water-absorbing powder to the bottom 21b of the housing groove 21 and to ensure good waterproof performance, it is necessary to suppress the housing density of the optical fiber 33 in the housing groove 21 to a certain extent.

  Therefore, in the optical fiber cable 10 according to the present embodiment, the groove width of the housing groove 21 on the outer peripheral side of the slot 11 is W, the groove depth of the housing groove 21 along the radial direction of the slot 11 is D, and the axial direction of the slot 11 When the cross-sectional area of the accommodation groove 21 orthogonal to is S1 and the total cross-sectional area of the optical fiber 33 accommodated in the accommodation groove 21 is S2, both conditions of the following expressions (1) and (2) are satisfied. It is configured.

S2 / S1 ≦ 0.6 (1)
S2 / S1 ≦ 0.2 (W / D) +0.3 (2)

  By satisfying these conditions, the water-absorbing powder adhering to the water-absorbing tape 13 can evenly enter the housing groove 21 and reach the bottom 21 b of the housing groove 21. Thereby, even if water permeates into the accommodation groove 21, the water-absorbing powder swells, and the inside of the accommodation groove 21 is reliably closed by the swollen water-absorbing powder. Therefore, the water that has entered the housing groove 21 is prevented from being transmitted in the axial direction, and the spread of the water is prevented. That is, it is possible to provide the optical fiber cable 10 in which the optical fibers 33 are accommodated at a high density while maintaining good waterproof performance.

  Moreover, according to the optical fiber cable 10 according to the present embodiment, an intermittently connected optical tape in which a plurality of optical tape core wires 31 in which a plurality of optical fibers 33 are integrated are intermittently connected to the receiving groove 21. The core 12 is accommodated. Therefore, the optical fiber 33 can be easily accommodated with high density. Thereby, the high-density optical fiber cable 10 which has favorable waterproof performance can be provided easily.

  In addition, since the slot 11 has a flexural rigidity of 1000 MPa or more and has an increased strength, a sufficient strength can be ensured even if the cross-sectional area of the slot 11 is reduced. As a result, without increasing the weight, the receiving groove 21 can be enlarged while the diameter is reduced to increase the number of optical fibers 33 accommodated, and the density can be further increased.

  In the housing groove 21 for housing the optical fiber 33, the ratio (S 2 / S 1) between the cross-sectional area S 1 of the housing groove 21 and the total cross-sectional area S 2 of the optical fiber 33 housed in the housing groove 21 and the groove width W of the housing groove 21. The optical fiber cable 10 having various structures with different ratios (W / D) of the groove depth D of the housing grooves 21 was tested. In this example, a waterproof test was performed on the optical fiber cable 10 in which S2 / S1 was 0.3 or more and optical fibers were accommodated at a high density.

(Test method)
FIG. 4 is a schematic side view of a test location for explaining the waterproof test.
As shown in FIG. 4, a non-waterproof portion A from which the water-absorbing tape 13 and the jacket 14 were removed was formed on the optical fiber cable 10. The non-waterproof portion A had an axial length of 2.5 cm and a distance from the exposed one end B of 4000 cm.

  The optical fiber cable 10 in which the non-waterproof part A was formed was passed through a water tank 42 provided with a pipe line 41 extending upward, and the non-waterproof part A was arranged in the water tank 42. Both ends of the water tank 42 and the jacket 14 of the optical fiber cable 10 were sealed. Water Wt was stored in the water tank 42. At this time, the initial head length, which is the height from the non-waterproof portion A to the water surface in the conduit 41, was set to 100 cm.

  The presence or absence of outflow of water Wt from the end B of the optical fiber cable 10 after 240 hours had elapsed since the water Wt was stored in the water tank 42 was examined. The case where the water Wt did not flow out from the end B of the optical fiber cable 10 was determined to pass the waterproof test (O), and the case where the water Wt flowed out from the end B of the optical fiber cable 10 was determined to be rejected (×). In addition, seawater was used as the water Wt, and the test was performed at room temperature.

(Test results)
FIG. 5 is a graph showing the waterproof test results.
As shown in FIG. 5, when W / D is 0.5, S2 / S1 is 0.5 or more, and water Wt flows out from the end B of the optical fiber cable 10. When W / D is 1.0, S2 / S1 is 0.6 or more, and water Wt flows out from the end B of the optical fiber cable 10. Furthermore, when W / D was 1.5 or more, S2 / S1 was 0.7 or more, and water Wt flowed out from the end B of the optical fiber cable 10.

  As described above, if the groove width W of the housing groove 21 is increased and the groove depth D is reduced, good waterproof performance can be obtained. However, the housing density of the optical fiber 33 in the housing groove 21 (S2 / S1). It has been found that the waterproof performance decreases as the value increases. That is, in order to ensure good waterproof performance, it was found that the accommodation density of the optical fiber 33 in the accommodation groove 21 needs to be suppressed to a predetermined value or less.

  And from the result of this waterproof test, the optical fiber is maintained while maintaining good waterproof performance by satisfying both conditions of S2 / S1 ≦ 0.6 and S2 / S1 ≦ 0.2 (W / D) +0.3. It turned out that the optical fiber cable 10 which accommodated 33 in the accommodation groove | channel 21 with high density is obtained.

  Next, a modified optical fiber cable 10A will be described with reference to FIGS. FIG. 6 shows a cross section of a modified optical fiber cable 10A, and FIG. 7 shows a partially enlarged cross section of one receiving groove 21 in the modified optical fiber cable 10A. FIG. 8 shows a cross section of one subunit 31.

  As shown in FIGS. 6 and 7, each accommodation groove 21 accommodates an optical fiber unit 70 formed by twisting a plurality of (four in this example) subunits 60.

  As shown in FIG. 8, one subunit 31 is formed by preparing a plurality (ten in the present example) of bundled intermittent optical tape cores 50 and twisting them together. .

9A is a cross-sectional view of the intermittent optical tape core 50 in a state of being gathered in a bundle, and FIG. 9B is an intermittent optical tape core before being gathered in a bundle. FIG.
As shown in FIGS. 9A and 9B, the intermittent optical tape core 50 includes a plurality (eight in this example) of optical fiber cores (an example of an optical fiber) 51a to 51h (hereinafter collectively referred to as the optical fiber cores). In this case, it is constituted by an optical fiber core wire 51). The intermittent optical tape core 50 is an aggregate of optical fiber cores by gathering these optical fiber cores 51a to 51h together into a bundle having a circular cross section as a whole.

  The intermittent optical tape core 50 is formed by intermittently cutting, in the longitudinal direction, joint portions of the eight optical fiber cores 51a to 51h that are integrated in parallel. The intermittent optical fiber core 50 of this example is intermittently connected at positions X in which the width directions of the adjacent optical fiber cores 51a to 51h are alternately different in the longitudinal direction. In addition, as the intermittent optical tape core wire 50, adjacent optical fiber core wires 51a to 51h may be intermittently bonded to each other.

  FIG. 10A shows a perspective view of the subunit 60. As shown in FIG. 10A, a tape-like bundle material 73 is wound around the outer periphery of the subunit 60. The bundle material 73 is spirally wound so as to bundle a plurality of intermittent optical tape core wires 50 that are twisted together to form the subunit 60.

  FIG. 10B shows a perspective view of the optical fiber unit 70. As shown in FIG. 10B, a tape-shaped bundle material 74 is wound around the outer periphery of the optical fiber unit 70. The bundle material 74 is spirally wound so as to bundle a plurality of subunits 60 that are twisted together to form the optical fiber unit 70.

  As the material of the bundle materials 73 and 74, polyethylene, polyethylene terephthalate, polyamide or the like is used, and the thickness is preferably 0.03 mm to 0.1 mm and the width is 1.0 mm to 10 mm. The tape-like bundle material described above is not limited to a tape-like material, and may be constituted by bundle yarns made of, for example, thread-like fibers.

  Thus, in this example, the intermittent optical tape core 50 is composed of eight optical fiber cores 51a to 51h. The subunit 60 is composed of ten intermittent optical tape cores 50 and a total of 80 optical fiber cores 51. The optical fiber unit 70 is composed of four subunits 60, and is composed of a total of 320 optical fiber cores 51. An optical fiber unit 70 is housed in each of the five housing grooves 21 of the slot 11. That is, the optical fiber cable 10A of this example is a high-density multi-core optical fiber cable including a total of 1600 optical fiber cores 51.

  Even in the configuration of this optical fiber cable 10A, as in the case of the optical fiber cable 10, both the conditions of S2 / S1 ≦ 0.6 and S2 / S1 ≦ 0.2 (W / D) +0.3 are satisfied. The optical fiber can be accommodated in the accommodation groove 21 with high density while maintaining good waterproof performance.

  The ten intermittent optical tape cores 50 constituting the subunit 60 accommodated in each accommodation groove 21 are different from each other in the color of the identification optical fiber core 51a. As a result, when the intermittent optical tape core 50 is taken out from each housing groove 21, the desired intermittent optical tape core 50 can be identified and taken out by the color of the optical fiber core 51a.

  In addition, this invention is not limited to embodiment mentioned above, A deformation | transformation, improvement, etc. are possible suitably. In addition, the material, shape, dimension, numerical value, form, number, arrangement location, and the like of each component in the above-described embodiment are arbitrary and are not limited as long as the present invention can be achieved.

  For example, the number of optical fibers in the above-described optical tape core, the number of optical tape cores in the intermittently connected optical tape, the number of intermittently connected optical tapes in the receiving groove, and the number of receiving grooves in the slot Etc. are not particularly limited.

10: Optical fiber cable 11: Slot 12: Intermittent connection type optical tape core 13: Water absorption tape 14: Outer sheath 21: Housing groove 31: Optical tape core wires 33 and 51 (51a to 51h): Optical fiber 50: Intermittent type Optical fiber 60: Sub unit 70: Optical fiber unit

Claims (4)

A slot in which a receiving groove is formed in the axial direction;
A plurality of optical fibers housed in the housing grooves;
Water absorbent powder is attached to the base fabric, and water absorbent tape wound around the slot;
A jacket covering the periphery of the slot via the water absorbing tape;
Have
The groove width of the housing groove on the outer peripheral side of the slot is W, the groove depth of the housing groove along the radial direction of the slot is D, the cross-sectional area of the housing groove orthogonal to the axial direction of the slot is S1, When the total cross-sectional area of the optical fiber accommodated in the accommodation groove is S2,
S2 / S1 ≦ 0.6 and S2 / S1 ≦ 0.2 (W / D) +0.3
An optical fiber cable that is configured to meet   A plurality of the optical fibers are arranged in parallel in the housing groove, and an intermittent optical tape core wire in which the width directions of the adjacent optical fibers are intermittently connected in the longitudinal direction is housed. Item 5. An optical fiber cable according to Item 1.   In the housing groove, a plurality of optical tape cores in which a plurality of the optical fibers are arranged in parallel are arranged in parallel, and ends in the width direction of the adjacent optical tape cores are in the longitudinal direction. The optical fiber cable according to claim 1 or 2, wherein intermittently connected optical tape cores that are intermittently connected are accommodated. The optical fiber cable according to any one of claims 1 to 3, wherein the slot has a flexural modulus of 1000 MPa or more.

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