JP6967472B2 - Fiber optic cable - Google Patents

Description

The present invention relates to an optical fiber cable.

Conventionally, an optical fiber cable as shown in Patent Document 1 below has been known. This optical fiber cable integrally covers a plurality of optical fiber tape core wires, a pair of separators, a pair of inclusions, and a pair of tensile strength bodies arranged across the optical fiber tape core wires, and these members. It has a jacket and a cover. In this optical fiber cable, by making a notch from the outer cover toward the separator, the optical fiber can be easily taken out while suppressing damage to the optical fiber. Further, when the outer cover is extruded, inclusions are arranged inside the outer cover in order to prevent the material to be the outer cover from entering the gaps between the optical fibers and making it difficult to take out the optical fibers. There is.

Japanese Unexamined Patent Publication No. 2014-219494

By the way, in this kind of optical fiber cable, a so-called intermittent fixing tape core wire may be used in order to improve the ease of cable connection work and intermediate / post-branching work while mounting more optical fibers. .. This is because the intermittent fixing tape core wire has many advantages such that it is easy to put it in and out of the closure because the rigidity of the whole is relatively small, it is possible to perform batch fusion splicing, and it is easy to take out each optical fiber. ..
Further, in order to more reliably protect the intermittent fixing tape core wire, a core may be formed by wrapping the intermittent fixing tape core wire together with an inclusion in a presser roll, and this core may be housed in the outer cover. Further, by using an inclusion having water absorption, running water in the optical fiber cable may be prevented.

However, when forming such a core, it has been found that the desired waterproof performance may not be obtained or inconvenience may occur due to a large deformation of the core depending on the position and state of inclusions.

The present invention has been made in consideration of such circumstances, and it is intended to reduce the deformation of the core due to inclusions while ensuring the waterproof performance due to inclusions in the optical fiber cable using the intermittent fixing tape core wire. The purpose.

In order to solve the above problems, the optical fiber cable according to the first aspect of the present invention has a plurality of optical fibers arranged in parallel, and intermittent fixing tapes in which optical fibers adjacent to each other are intermittently fixed in the longitudinal direction. A core formed by wrapping a core wire and an inner inclusion in a presser roll, an outer inclusion arranged outside the core, a pair of separators arranged across the core, and the core. It includes a pair of tensile strength bodies arranged sandwiched between the core, the outer inclusions, the pair of separators, and a jacket that integrally covers the pair of tensile strength bodies.

According to the optical fiber cable according to the above aspect, by arranging inclusions both inside and outside the core, it is possible to prevent running water both inside and outside the core and ensure waterproof performance. can.
Further, as compared with the case where the inclusions are arranged only on the outside of the core, for example, by arranging the inclusions separately on both the inside and the outside of the core, the deformation of the core due to the outer inclusions pressing the core. Can be reduced.

According to the above aspect of the present invention, in the optical fiber cable using the intermittent fixing tape core wire, it is possible to reduce the deformation of the core due to the inclusions while ensuring the waterproof performance due to the inclusions.

It is sectional drawing of the optical fiber cable of this embodiment. It is explanatory drawing of the optical fiber unit of FIG. It is sectional drawing of the optical fiber cable of the comparative example.

Hereinafter, the configuration of the optical fiber cable according to the present embodiment will be described with reference to FIGS. 1 to 3. In each drawing used in the following description, the scale is appropriately changed in order to make each member a recognizable size.
As shown in FIG. 1, the optical fiber cable 100 includes a core 3 having an optical fiber unit 10, an outer inclusion 40B, a pair of tensile strength bodies 20, a pair of separators 30, a support wire 50, and an outer cover 60. And have.

Here, in the present embodiment, the XYZ Cartesian coordinate system is set and the positional relationship of each configuration will be described. The X direction is the extending direction of the optical fiber cable 100. The Y direction is the direction in which the pair of tensile strength bodies 20 face each other. The Z direction is a direction orthogonal to both directions of the X direction and the Y direction. Hereinafter, the X direction is referred to as a longitudinal direction, the Y direction is referred to as a left-right direction, and the Z direction is referred to as a vertical direction. A cross section orthogonal to the longitudinal direction is called a cross section.

As shown in FIG. 2, the optical fiber unit 10 of the present embodiment is a so-called intermittent fixing tape core wire, and is formed by intermittently connecting a plurality of optical fibers 1 to each other by a connecting portion 11. More specifically, a plurality of optical fibers 1 are arranged in parallel, and adjacent optical fibers 1 are connected by a connecting portion 11. The connecting portions 11 are arranged at regular intervals in the longitudinal direction. The connecting portion 11 that connects the adjacent optical fibers 1 to each other next to the adjacent optical fibers 1 is arranged at a position shifted in the longitudinal direction with respect to the position of the connecting portion 11 that connects the adjacent optical fibers 1 to each other. ing. As described above, the connecting portions 11 are arranged in a staggered manner in the longitudinal direction and in both directions in the width direction orthogonal to the longitudinal direction. The connecting portion 11 is formed of, for example, a UV curable resin or the like, and is adhered to the optical fibers 1 adjacent to each other to connect the optical fibers 1 to each other. The optical fibers 1 connected to each other by the connecting portion 11 are separated from the optical fiber 1 by the force of the fingers, for example, by pulling the optical fibers 1 so as to be separated from each other in the width direction of the optical fiber unit 10 by a finger. The connected state can be released.
The optical fiber unit 10 is not limited to the intermittent fixing tape core wire, and for example, a plurality of optical fibers 1 bundled with a binding material or the like may be used.

As the optical fiber 1, an optical fiber wire, an optical fiber core wire, or the like can be used. The primary layer or secondary layer covering the bare wire of the optical fiber 1 is preferably formed of a UV curable resin. In order to identify the optical fiber 1, the secondary layer itself may be colored, or a colored layer may be further provided on the outer periphery of the secondary layer. Alternatively, the outer periphery of the optical fiber 1 may be marked for identification.

As shown in FIG. 1, the core 3 is formed by wrapping the optical fiber unit 10 and the inner inclusions 40A with the presser winding 2. The inner inclusions 40A are arranged inside the presser roll 2.
As the presser roll 2, a plastic tape member or the like can be used. As the material of the presser winding 2, for example, polyethylene terephthalate (PET) can be used.
As the inner inclusion 40A, it is desirable to use a yarn whose fineness can be freely changed. As the material for forming the inner inclusions 40A, for example, polypropylene (PP), polyester (PEs), or the like can be used. In this embodiment, PP yarn is used as the inner inclusion 40A. The material of the inner inclusions 40A is not limited to PP yarn, and a part or all of the inner inclusions 40A may be replaced with water-absorbing yarn or the like.

In the present embodiment, the optical fiber unit 10 and the inner inclusions 40A are wrapped by the presser winding 2 in a state of being twisted in an SZ shape. As a result, it is possible to facilitate intermediate post-branching work while suppressing the action of tension or lateral pressure on the optical fiber 1.
The optical fiber unit 10 and the inner inclusions 40A may be twisted in a spiral shape.

The outer inclusions 40B are arranged in the gap between the presser roll 2 and the outer cover 60, that is, on the outside of the core 3. The outer inclusions 40B can be formed by using PP yarn or the like, similarly to the inner inclusions 40A. In this way, by arranging the inner inclusions 40A and the outer inclusions 40B on the inner and outer sides of the core 3, respectively, it is possible to prevent running water on both the inner and outer sides of the core 3. The inner inclusions 40A also play a role of securing the volume of the accommodation space described later when the number of cores of the optical fiber 1 contained in the core 3 is small. That is, when the outer cover 60 is extruded and molded, the inner inclusions 40A resist the pressure of the resin that becomes the outer cover 60, so that it is possible to prevent the accommodation space from becoming excessively narrow. In addition, in order to properly form the accommodation space, the upper and lower limit values of the cross-sectional area of the accommodation space are set, and the amount of the inner inclusions 40A is adjusted so that the cross-sectional area of the accommodation space is within the range of the upper and lower limit values. May be good.

The pair of tensile strength bodies 20 are arranged so as to sandwich the core 3 and the outer inclusions 40B in the left-right direction. As the tensile strength body 20, steel wire, metal fiber, aramid fiber, glass fiber, carbon fiber, FRP (fiber reinforced plastic) and the like can be used. The tensile strength body 20 plays a role of suppressing the action of this tension on the optical fiber 1 against the tension acting on the optical fiber 1 in the longitudinal direction.

The pair of separators 30 are arranged so as to sandwich the core 3 and the outer inclusions 40B in the vertical direction. Each separator 30 is formed in a plate shape extending in the left-right direction in a cross-sectional view, and is arranged substantially parallel to each other. The outer cover 60 is partially inserted between the pair of separators 30 from both the left and right sides. The pair of separators 30 and the outer cover 60 inserted between the pair of separators form a substantially rectangular accommodation space in a cross-sectional view. The core 3 and the outer inclusions 40B are arranged in this substantially rectangular accommodation space.

As the material of the separator 30, a sheet material such as polypropylene, polyamide, or polyimide can be used. The separator 30 is preferably formed of a material having a melting point higher than the melting point of the outer cover 60 in order to prevent it from being fused with the outer cover 60 when the outer cover 60 is extruded.

The support wire 50 is formed of a steel wire or the like. The outer diameter of the support wire 50 is larger than the outer diameter of the tensile strength body 20. The support line 50 and the pair of tensile strength bodies 20 are arranged side by side in the left-right direction. The support wire 50 is used as a suspension wire for fictitious use of the optical fiber cable 100. The optical fiber cable 100 does not have to include the support wire 50.

The outer cover 60 has a first covering portion 60a, a second covering portion 60b, and a connecting portion 60c for connecting the first covering portion 60a and the second covering portion 60b to each other.
The first covering portion 60a integrally covers the core 3, the outer inclusions 40B, the pair of separators 30, and the pair of tensile strength bodies 20. The second covering portion 60b covers the support wire 50.

The first covering portion 60a is formed in a substantially rectangular shape in a cross-sectional view. A notch 60n is formed in a portion of the first covering portion 60a that covers the separator 30. The notch 60n is formed in a V shape in a cross-sectional view, and the width gradually decreases toward the separator 30. A pair of notches 60n are formed on the upper end surface and the lower end surface of the first covering portion 60a, respectively.
When the core 3 is taken out from the optical fiber cable 100, a cutting blade or the like is brought into contact with each notch 60n to cut through the first covering portion 60a covering the separator 30. As a result, the first covering portion 60a can be divided and the core 3 can be easily taken out.

The material of the jacket 60 includes polyolefins such as polyethylene (PE), polypropylene (PP), ethylene ethyl acrylate copolymer (EEA), ethylene vinyl acetate copolymer (EVA), and ethylene propylene copolymer (EP). PO) resin, polyvinyl chloride (PVC) and the like can be used. The outer cover 60 can be formed by extrusion molding or the like. Even in this case, since the optical fiber unit 10 is wrapped with the presser winding 2, it is possible to prevent the outer cover 60, which flows at a high temperature, from entering the gap between the optical fibers 1. It is desirable that the set temperature when the outer cover 60 is extruded is lower than the melting point of the separator 30 or the presser winding 2 so that the separator 30 and the presser winding 2 and the outer cover 60 do not fuse.

Hereinafter, the above embodiment will be described with reference to specific examples. The following examples do not limit the present invention.

(Example 1)
In the optical fiber cable 100 of this embodiment, a four-core intermittent fixing tape core wire is used as the optical fiber unit 10, and six intermittent fixing tape core wires are wrapped in a presser winding 2. As the inner inclusions 40A, one 1670 dtex PEs water-absorbing yarn was used. As the outer inclusions 40B, one 1670 dtex PEs water-absorbing yarn was used. As the presser foot 2, a PET tape material having a thickness of 0.25 mm was used. The thickness of the first covering portion 60a in the vertical direction is about 3.5 mm, and the width in the horizontal direction is about 5.5 mm. The mounting density of the optical fiber 1 in the accommodation space formed by the pair of separators 30 and the outer cover 60 inserted between the separators 30 is within the range of ^{8.5 to 10.9 fibers / mm 2.} became. The mounting density of the optical fiber is a numerical value defined by the following mathematical formula (1). In formula (1), d is the mounting density of the optical fiber, N is the number of cores of the optical fiber, S is the cross-sectional area of the accommodation space, and P is each member (inner inclusions 40A, outer inclusions) accommodated in the accommodation space. 40B, the sum of the cross-sectional areas of the presser winding 2).
d = N ÷ (SP) ... (1)

Here, by setting the mounting density d of the optical fiber within a predetermined range, the following advantages can be obtained. That is, if the mounting density d of the optical fiber is too small, the possibility that the optical fiber 1 moves in the accommodation space increases. In addition, the running water length during the water discharge test becomes long, and the possibility of failing the water discharge test increases. On the other hand, if the mounting density d of the optical fiber is too large, the transmission loss may increase.
The numerical range of the mounting density d described above is suitable as an index for achieving the desired performance of the optical fiber cable, for example, when the amounts of the inner inclusions 40A and the outer inclusions 40B are fixed. However, the above-mentioned mounting density d is not limited to the present invention, and the optical fiber cable may be defined by an index other than the mounting density d, depending on the type, shape, application, and the like of the optical fiber cable.

Under the above conditions, the optical fiber unit 10 and the inner inclusions 40A were twisted by SZ and wrapped with a presser winding 2 to form a core 3. Further, while forming the core 3, the outer inclusions 40B and the like were vertically attached to the core 3, and the first covering portion 60a was extruded and molded around each member. Here, when a plurality of optical fiber cables 100 were created by changing the tension of the outer inclusions 40B when covering the outer inclusions 40B with the first covering portion 60a, the residual length ratio was 99.85% to 100. It was in the range of .2%. The extra length ratio means the ratio of the length of the outer inclusions 40B in the non-tensioned state to the length of the outer cover 60 in the longitudinal direction. The length of the outer inclusions 40B in the non-tensioned state was measured by removing the outer inclusions 40B from the outer cover 60.

As described above, Table 1 below shows the results of confirming the transmission loss and the waterproof performance of the plurality of optical fiber cables 100 having different extra length ratios. In this example, the transmission loss at a wavelength of 1550 nm was measured by an OTDR (Optical Time Domain Reflectometer). In addition, Table 1 below shows the maximum value of the transmission loss of 24 optical fibers 1 included in each optical fiber cable 100.
The waterproof test was carried out in accordance with IEC 60794-1-22 F5B under the conditions of a head length of 1 m and 24 hours using tap water. As a result, the case where the running water length was 3 m or less was passed, and the case where the running water length exceeded 3 m was rejected.

As shown in Table 1, in the range of the surplus length ratio of 99.95% or more (Example 1), the transmission loss was 0.25 dB / km or less and the running water length was 3 m or less, and good results were obtained. ..
On the other hand, when the extra length ratio was 99.85% (Comparative Example 1), the transmission loss was 0.28 dB / km, and the transmission loss was larger than that of Example 1, resulting in a failure. .. It is considered that this is because Comparative Example 1 has a larger tension acting on the outer inclusion 40B than that of Example 1.

That is, when the tension of the outer inclusions 40B is large, it is considered that the outer inclusions 40B are strongly pressed against the core 3 and a lateral pressure acts on the optical fiber 1 to increase the transmission loss. Further, when the tension of the outer inclusions 40B is large, the flow of the resin material to be the first coating portion 60a changes when the first coating portion 60a is extruded, and the core 3 is accommodated in the first coating portion 60a. It is possible that the space will become smaller. When the accommodation space of the core 3 becomes small in this way, it is considered that the lateral pressure acts on the optical fiber 1 and the transmission loss increases.
From the above, in order to keep the tension of the outer inclusions 40B within an appropriate range and suppress an increase in transmission loss, it is preferable to set the extra length ratio of the outer inclusions 40B to 99.95% or more.

When the extra length ratio is 100.3% or more, when the first covering portion 60a covers the outer inclusions 40B, the tension acting on the outer inclusions 40B is too low, so that the light is stable. It was difficult to manufacture the fiber cable 100.
Therefore, from the viewpoint of stably manufacturing the optical fiber cable 100, the extra length ratio is more preferably 100.2% or less.

(Comparative Example 2)
Next, the optical fiber cable 100A of Comparative Example 2 as shown in FIG. 3 was manufactured and its performance was confirmed. The optical fiber cable 100A of Comparative Example 2 does not have the inner inclusions 40A, and the inclusions in the combined amount of the inner inclusions 40A and the outer inclusions 40B in Example 1 are arranged as the outer inclusions 40C. bottom. That is, the optical fiber cable 100A of Comparative Example 2 has the same configuration as the optical fiber cable 100 of Example 1 except that the inner inclusions 40A of Example 1 are arranged outside the core 3.

As shown in Table 1, in the optical fiber cable 100A of Comparative Example 2, the running water length exceeded 3 m, and the result of the waterproof test was unacceptable. This is because the running water in the core 3 could not be suppressed because the inclusions were not present inside the presser roll 2. From this, it can be seen that the inner inclusion 40A in the first embodiment improves the waterproof performance of the optical fiber cable 100.

Further, as shown in FIG. 3, in the optical fiber cable 100A of Comparative Example 2, the presser winding 2 is largely recessed toward the inside of the core 3 by the outer inclusion 40C. When the core 3 is greatly deformed in this way, when the optical fiber unit 10 is twisted inside the core 3, the optical fiber unit 10 is caught in the recessed portion of the presser winding 2 and is not properly twisted. There is. In particular, when the optical fiber unit 10 and the inner inclusions 40A are twisted by SZ, this twisting is likely to be hindered by the deformation of the core 3.

On the other hand, in the optical fiber cable 100 of the first embodiment shown in FIG. 1, the inclusions 40A and 40B are separately arranged both inside and outside the core 3, so that the deformation of the core 3 is reduced. ing. Therefore, it is possible to suppress the occurrence of inconveniences such as the optical fiber unit 10 not being properly twisted.

As described above, according to the optical fiber cable 100 of the present embodiment, the inclusions 40A and 40B are arranged both inside and outside the core 3, so that the run can be carried out both inside and outside the core 3. It can prevent water and ensure waterproof performance.
Further, as compared with the case where the inclusions are arranged only on the outside of the core 3, for example, by arranging the inclusions separately on both the inside and the outside of the core 3, the outer inclusions press the core 3. Deformation of the core 3 can be reduced.

Further, by setting the extra length ratio of the outer inclusions 40B to 99.95% or more, the transmission loss of the optical fiber 1 can be suppressed to a small value.
Further, by setting the extra length ratio of the outer inclusions 40B to 100.2% or less, the optical fiber cable 100 can be manufactured more stably.

The technical scope of the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.

For example, in the first embodiment, a four-core intermittent fixed tape core wire is used as the optical fiber unit 10, and the total number of cores included in the core 3 is 24, but the number of cores of the optical fiber unit 10 and the core 3 are set. The total number of cores included can be changed as appropriate. For example, under the conditions of Example 1, when the total number of cores 3 is changed, the mounting density ^{becomes 6.5 to 13.5 lines / mm 2 in} the case of 8 cores, and 6.8 to 1 in the case of 12 cores. It was 10.6 lines / mm ² . Further, when the size of the first covering portion 60a was made larger than that of the first embodiment and the core 3 having 48 cores was used, the mounting density was 7.5 to 9.0 lines / mm ² .

In addition, it is possible to replace the constituent elements in the above-described embodiment with well-known constituent elements as appropriate without departing from the spirit of the present invention, and the above-described embodiments and modifications may be appropriately combined.

1 ... Optical fiber 2 ... Press winding 3 ... Core 10 ... Optical fiber unit (intermittent fixing tape core wire) 20 ... Tensile body 30 ... Separator 40A ... Inner inclusions 40B ... Outer inclusions 50 ... Support wire 60 ... Cover 100 ... Fiber optic cable

Claims (4)

A core formed by wrapping multiple optical fibers and inner inclusions in a presser foot,
With the outer inclusions placed on the outside of the core,
With an outer cover covering the core and outer inclusions,
The core is in contact with the jacket
The outer inclusions are placed in the gap between the core and the jacket.
An optical fiber cable in which the outer inclusions and the inner inclusions are fibrous and have water absorption. A core formed by wrapping multiple optical fibers and inner inclusions in a presser foot,
With the outer inclusions placed on the outside of the core,
With an outer cover covering the core and outer inclusions,
The core is in contact with the jacket
The outer inclusions are placed in the gap between the core and the jacket.
The outer inclusion is an optical fiber cable vertically attached to the core. A core formed by wrapping multiple optical fibers and inner inclusions in a presser foot,
With the outer inclusions placed on the outside of the core,
With the jacket covering the core and outer inclusions,
With a pair of separators arranged across the core,
The outer cover is formed in a rectangular shape in a cross-sectional view, and is formed in a rectangular shape.
Each separator is an optical fiber cable located between the core and the jacket. The outside of the inside of the accommodation space is made form by the casing and the pair of separators,
Oite the cross section perpendicular to the longitudinal direction of the optical fiber cable, the number of the optical fiber disposed in the housing space is N, the cross-sectional area of the housing space and S, it is housed in the housing space When the sum of the cross-sectional areas of the members is P, the mounting density d of the optical fiber and the number N of the optical fibers defined by d = N ÷ (SP) are the conditions of any of the following A to D. The optical fiber cable according to claim 3 , which satisfies the above conditions.
A: N = 8 and d = 6.5-13.5 lines / mm2
B: N = 12 and d = 6.8 to 10.6 lines / mm2
C: N = 24 and d = 8.5-10.9 lines / mm2
D: N = 48 and d = 7.5-9.0 lines / mm2

Images