JP6775058B2 - Fiber optic cable - Google Patents

Description

The present invention relates to an optical fiber cable in which a plurality of optical fiber strands are bonded in parallel.

As an optical fiber for transmitting a large amount of data at high speed, an optical fiber tape core wire in which a plurality of optical fiber strands are arranged in parallel and bonded is used for storage in a cable and simplification of work. ing. As the optical fiber tape core wire, one in which parallel optical fiber strands are fixed with resin over the entire length is used, and there is one in which optical fiber strands are intermittently bonded to each other (for example, Patent Document 1). ..

Japanese Unexamined Patent Publication No. 2010-8923

By using such an intermittently bonded optical fiber tape core wire, even in an optical fiber cable in which an optical fiber is mounted at a high density, a large strain is not applied to the optical fiber core wire when the optical fiber cable is bent. This is because the optical fiber core wire can move freely in a single core state in the non-connecting portion of the intermittent adhesive type optical fiber tape mounted on the cable.

However, the inventors have found that when a plurality of intermittently bonded optical fiber tape core wires are inserted into the cable, the movement of the optical fiber core wires is hindered depending on the position of the bonded portion.

More specifically, when the positions of the connecting portions of the optical fiber tape cores completely overlap each other, the movement of the optical fiber cores constituting the intermittently bonded optical fiber tape cores is hindered and the transmission characteristics deteriorate. I found that.

The present invention has been made in view of such a problem, and an object of the present invention is to provide an optical fiber cable provided with an intermittent adhesive type optical fiber tape core wire and having good transmission characteristics.

In order to achieve the above-mentioned object, the present invention includes a plurality of optical fiber tape core wires, a coating layer for protecting the plurality of the optical fiber tape core wires, and a tension member provided inside the coating layer. The tension member bears the tension of the optical fiber cable, the optical fiber tape core wire is formed by arranging a plurality of optical fiber strands, and the adjacent optical fiber strands are the lengths of the optical fiber strands. The bonded portions are intermittently bonded to each other, the length of the bonded portions in the longitudinal direction and the distance between the bonded portions in the longitudinal direction are substantially equal, and the bonded portions adjacent to each other are formed with a half pitch shift in the longitudinal direction. The optical fiber cable is composed of a plurality of the optical fiber tape core wires accommodated in the optical fiber cable, the space factor of which the optical fiber cross section occupies in the total cross-sectional area of the optical fiber cable is 50% or more. When the positions of the adhesive portions in the longitudinal direction of the above are deviated from each other and any of the optical fiber tape core wires is used as the reference optical fiber tape core wire among the plurality of the optical fiber tape core wires, the reference is used. The tip position of an arbitrary adhesive portion of the optical fiber tape core wire is set as the reference adhesive portion position, and the optical fiber tape core wire is adhered closest to each of the other optical fiber tape core wires in the longitudinal direction of the optical fiber cable from the reference adhesive portion position. When the tip position of the portion is set to each bonding portion position, the deviation range with respect to the longitudinal direction of the optical fiber cable including all of the reference bonding portion position and each bonding portion position is 1 / of the length of the bonding portion. more der is, the longitudinal length of the adhesive portion L (mm), the number of the longitudinal spacing of the bonding portions and D (mm), the optical fiber ribbon is housed n As a book, the relationship of (n-1) × L ≦ (DL) / 2 is satisfied, and the length of the bonded portion in the longitudinal direction and the distance between the bonded portions in the longitudinal direction are substantially equal. The optical fiber cable is characterized in that the positions of the adhesive portions of all the optical fiber tape core wires in the longitudinal direction of the optical fiber cable do not overlap each other .

According to the first invention, when a plurality of optical fiber tape core wires are accommodated, the longitudinal positions of the adhesive portions do not completely match, so that the binding force of each optical fiber tape core wire is weak and one place. It is possible to suppress the application of concentrated stress to the optical fiber cable, and in particular, the maximum deviation distance with respect to the longitudinal direction of the optical fiber cable including all of the reference adhesive portion position and each adhesive portion position is the length of the adhesive portion. Since it is ½ or more of the above, the restraint between the core wires of each optical fiber tape can be further suppressed.

Also, all of the optical fiber ribbon, the position of the bonding portion in the longitudinal direction of the optical fiber cable, by not overlap each other, it is possible to increase the transmission loss reduction effect.

According to the present invention, it is possible to provide an optical fiber cable provided with an intermittent adhesive type optical fiber tape core wire and having good transmission characteristics.

The cross-sectional view which shows the optical fiber cable 1. The figure which shows the optical fiber tape core wire 3a, 3b, 3c, 3d, 3e. The figure which shows the optical fiber tape core wire 3a, 3b, 3c, 3d, 3e. The figure which shows the optical fiber tape core wire 3a, 3b, 3c, 3d, 3e. The figure which shows the optical fiber tape core wire 3a, 3b.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view showing an optical fiber cable 1. The optical fiber cable 1 is mainly composed of an optical fiber tape core wire 3, a buffer layer 5, a coating layer 7, a tension member 9, a tear cord 11, and the like.

The optical fiber tape core wire 3 is an optical fiber core wire in which a plurality of optical fiber strands are arranged in parallel and integrated. Details of the optical fiber tape core wire 3 will be described later.

A buffer layer 5 is provided on the outer periphery of the optical fiber tape core wire 3. The buffer layer 5 protects the optical fiber tape core wire 3 from external forces and the like.

A coating layer 7 is formed on the outer periphery of the buffer layer 5. The coating layer 7 is a layer for coating and protecting the optical fiber cable 1. A tension member 9 is provided inside the coating layer 7.

The tension member 9 bears the tension of the optical fiber cable 1. The tension member 9 is made of, for example, a steel wire or a fiber reinforced plastic. Further, a tear string 11 is embedded in the covering layer 7 as needed.

The problem assumed in the present application remarkably occurs when the fiber space factor in the cable is high. Usually, when manufacturing a cable, the optical fiber space factor is 50% or more in order to secure space efficiency by increasing the space factor (the ratio of the optical fiber cross section in the total cross section) as much as possible. In the present invention, the effect can be obtained by applying to all such optical fiber cables having an optical fiber space factor of 50% or more.

The optical fiber cable of the present invention is not limited to the illustrated example. It can also be applied to loose tube type cables and slot type optical fibers in which the tension member is placed in the center.

FIG. 2 is a perspective view showing a plurality of optical fiber tape core wires 3 (hereinafter, each of them is referred to as an optical fiber tape core wire 3a, 3b, 3c, 3d, 3e). In the illustrated example, a plurality of optical fiber tape core wires 3a, 3b, 3c, 3d, and 3e are aligned, but as shown in FIG. 1, each optical fiber tape core wire 3a, 3b The orientations and arrangements of 3c, 3d, and 3e are not uniform.

Further, in the following description, for the sake of simplicity, five optical fiber tape core wires 3a, 3b, 3c, 3d, and 3e will be described as an example, but all the optical fiber tape core wires accommodated in the optical fiber cable 1 will be described. It shall be applied to 3.

Further, in the following description, an example is shown in which the optical fiber tape core wires 3a, 3b, 3c, 3d, and 3e are each composed of four optical fiber strands 13, but the present invention is not limited to this, and a plurality of them. It is applicable as long as it is an optical fiber tape core wire composed of the optical fiber strands of.

The optical fiber tape core wires 3a, 3b, 3c, 3d, and 3e are each formed by bonding a plurality of optical fiber strands 13 in parallel.

The optical fiber tape core wires 3a, 3b, 3c, 3d, and 3e are bonded to each other by the adhesive portion 15 in which the adjacent optical fiber strands 13 are intermittently bonded to each other at predetermined intervals. Adhesive portions 15 between adjacent optical fiber strands are arranged so as to be offset from the longitudinal direction of the optical fiber tape core wires 3a, 3b, 3c, 3d, 3e, and 3e. For example, it is desirable that the adhesive portions 15 adjacent to each other are formed with a half pitch shift in the longitudinal direction of the optical fiber tape core wires 3a, 3b, 3c, 3d, and 3e.

FIG. 3 is a plan view in a state where the optical fiber tape core wires 3a, 3b, 3c, 3d, and 3e are provided side by side. The A direction in FIG. 3 is the longitudinal direction of the optical fiber cable 1. That is, FIG. 3 is a diagram showing the longitudinal positions of the adhesive portions 15 of the optical fiber tape core wires 3a, 3b, 3c, 3d, and 3e in the optical fiber cable 1. Therefore, the direction perpendicular to A in FIG. 3 indicates the same position in the longitudinal direction of the optical fiber cable 1.

The adhesive portions 15 of the optical fiber tape core wires 3a, 3b, 3c, 3d, and 3e all have the same length and the same pitch. Further, in each of the optical fiber tape core wires 3a, 3b, 3c, 3d, and 3e, the adjacent adhesive portions 15 are shifted by half a pitch from each other.

In the present invention, the positions of the adhesive portions 15 of all the optical fiber tape core wires 3a, 3b, 3c, 3d, and 3e are deviated from each other in the longitudinal direction. That is, the positions of the adhesive portions 15 of the optical fiber tape core wires 3a, 3b, 3c, 3d, and 3e in the longitudinal direction do not completely match.

As described above, since the positions of the adhesive portions 15 in the longitudinal direction are not completely matched and are displaced, the optical fiber tape core wires 3a, 3b, 3c, 3d, and 3e are not partially completely constrained.

For example, if the positions of the adhesive portions 15 of the adjacent optical fiber tape core wires coincide with each other by chance, stress may be concentrated on this portion when bending deformation or the like is applied to the optical fiber cable 1. There is. On the other hand, if the position of the adhesive portion 15 is slightly deviated, the arrangement of the optical fiber tape core wires is likely to change as a result of the deviation.

Here, the length of the adhesive portion 15 of the optical fiber tape core wires 3a, 3b, 3c, 3d, and 3e in the longitudinal direction is L (mm). Further, the distance between the adhesive portions 15 in the longitudinal direction is D (mm). That is, in the optical fiber tape core wires 3a, 3b, 3c, 3d, and 3e, all the optical fiber strands 13 are adhered with the same D and L.

Further, a certain optical fiber tape core wire is used as a reference optical fiber tape core wire. In the example shown in FIG. 3, the optical fiber tape core wire 3a is used as the reference optical fiber tape core wire. Further, the tip position of an arbitrary adhesive portion 15 of the reference optical fiber tape core wire (the left end portion is the tip position in the figure) is set as the reference adhesive portion position (C in the figure).

In this case, B is the distance between the farthest positions (tip and rear end) of the tip positions of the adhesive portion 15 closest to the reference adhesive portion position C of the optical fiber tape core wires 3b, 3c, 3d, and 3e. .. The reference adhesive portion position C may be the most advanced or the rearmost end.

In this case, if the maximum deviation amount B is small, the effect of shifting the position of the adhesive portion 15 of the optical fiber tape core wires 3a, 3b, 3c, 3d, and 3e is small. For example, in the example shown in FIG. 3, since the maximum deviation amount B is less than 1/2 of the length L of the bonded portion 15, the effect of suppressing stress concentration is small.

FIG. 4 is a diagram similar to FIG. 3, showing a state in which the amount of deviation of the adhesive portion 15 is changed. In the example shown in FIG. 4, the maximum deviation amount B is ½ or more of the length L of the adhesive portion 15.

When the maximum deviation amount B is ½ or more of the length L of the bonded portion 15, the effect of suppressing stress concentration is large. For example, an increase in transmission loss or the like, which is a subject of the present invention, is more likely to occur as the number of overlapping portions increases. Therefore, if at least a part of the adhesive portions 15 of the optical fiber tape cores are displaced by a length of 1/2 or more in the longitudinal direction, at least the interference of the adhesive portions 15 of the optical fiber tape cores is suppressed. be able to.

More preferably, the amount of displacement between all the optical fiber tape core wires is 1/2 or more of the length L of the adhesive portion 15. By doing so, the adhesive portions 15 of all the optical fiber tape core wires do not overlap with each other at a length of 1/2 or more of the adhesive portions 15, so that the transmission loss reduction effect is great.

In this case, assuming that the number of optical fiber tape core wires to be accommodated is n, it is necessary to satisfy the relationship of (n-1) × L / 2 ≦ (DL) / 2. That is, it is necessary to satisfy the relationship of nL ≦ D.

FIG. 5 is a diagram similar to FIG. 3 (however, for simplicity, only the optical fiber tape core wires 3a and 3b are shown), and is a diagram showing a state in which the deviation amount of the adhesive portion 15 is further changed. In the example shown in FIG. 5, the adhesive portions 15 do not completely overlap. That is, the maximum deviation amount B is equal to or greater than the length L of the bonded portion 15.

As described above, since the adhesive portions of the pair of optical fiber tape core wires do not completely overlap each other, the transmission loss reduction effect is great.

It is desirable that the adhesive portions of a plurality of pairs of optical fiber tape core wires do not completely overlap each other instead of a pair. Furthermore, it is desirable that all the bonded portions do not completely overlap each other.

In this case, assuming that the number of optical fiber tape core wires to be accommodated is n, it is necessary to satisfy the relationship of (n-1) × L ≦ (DL) / 2. That is, it is necessary to satisfy the relationship of (2n-1) L ≦ D.

As described above, according to the present invention, when a plurality of optical fiber tape core wires are accommodated, the positions of the adhesive portions 15 in the longitudinal direction do not completely match, so that the optical fiber strands 13 constituting each optical fiber tape core wire 13 The binding force is weak, and it is possible to suppress the application of stress concentrated in one place.

Further, when the maximum deviation amount B is ½ or more of the length L of the bonded portion, the restraint of the optical fiber strands 13 constituting each optical fiber tape core wire can be further suppressed.

Further, by preventing the positions of the adhesive portions 15 in the longitudinal direction of at least one set of optical fiber tape core wires from overlapping each other, interference between the adhesive portions 15 is suppressed, and the optical fiber strands 13 are restrained more. It can be suppressed.

Although the embodiments of the present invention have been described above with reference to the accompanying drawings, the technical scope of the present invention does not depend on the above-described embodiments. It is clear that a person skilled in the art can come up with various modifications or modifications within the scope of the technical ideas described in the claims, and these are naturally within the technical scope of the present invention. It is understood that it belongs.

1 ………… Optical fiber cable 3, 3a, 3b, 3c, 3d, 3e ………… Optical fiber tape core wire 5 ………… Buffer layer 7 ………… Coating layer 9 ………… Tension member 11 ………… Tear string 13 ……… Optical fiber wire 15 ……… Adhesive part

Claims (1)

With multiple optical fiber tape core wires,
A coating layer that protects the plurality of optical fiber tape core wires,
A tension member provided inside the coating layer and
Equipped with
The tension member bears the tension of the optical fiber cable and
The optical fiber tape core wire is formed by arranging a plurality of optical fiber strands.
Adjacent optical fiber strands are intermittently bonded to each other in the longitudinal direction of the optical fiber strands, and the length of the bonded portion in the longitudinal direction and the distance between the bonded portions in the longitudinal direction are almost equal and are adjacent to each other. The adhesive portion is formed with a half pitch shift in the longitudinal direction.
The space factor, which is the ratio of the optical fiber cross section to the total cross section in the optical fiber cable, is 50% or more.
The positions of the adhesive portions of the plurality of optical fiber tape core wires accommodated in the optical fiber cable in the longitudinal direction of the optical fiber cable are deviated from each other.
When any of the optical fiber tape core wires is used as the reference optical fiber tape core wire, the tip position of an arbitrary adhesive portion of the reference optical fiber tape core wire is set as the reference adhesive portion. When the position is set and the tip position of the adhesive portion closest to the reference adhesive portion position in the longitudinal direction of the optical fiber cable is set as the respective adhesive portion position with respect to each of the other optical fiber tape core wires, the reference adhesive portion is used. including all parts position and the respective bonding portions positional deviation range with respect to the longitudinal direction of the optical fiber cable state, and are more than half of the length of the bonding portion,
Assuming that the length of the adhesive portion in the longitudinal direction is L (mm), the distance between the adhesive portions in the longitudinal direction is D (mm), and the number of the optical fiber tape core wires accommodated is n, (n). -1) × L ≦ (DL) / 2 is satisfied,
The positions of the adhesive portions in the longitudinal direction of the optical fiber cable of all the optical fiber tape core wires having approximately the same longitudinal length of the adhesive portion and the longitudinal distance between the adhesive portions do not overlap each other. An optical fiber cable characterized by this.

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