JP3748917B2 - Fiber optic cable - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to an optical fiber cable using an optical fiber core wire formed by integrally joining a plurality of optical fiber strands arranged in parallel at intervals in the length direction.
[0002]
[Prior art]
In recent years, in an aerial optical cable, in order to increase the mounting density of optical fibers, a plurality of optical fiber strands 1 are arranged in parallel as shown in FIG. Hereinafter, the tape core wire is often used.
[0003]
However, in such a tape core wire, since the plurality of optical fiber strands 1 are coupled and integrated over the entire length, the drawing to the subscriber system must be performed in units of tape core wires. In other words, when the demand at one withdrawal point is 1 to 2 cores, the remaining optical fibers remain unused and there is a problem that the use efficiency is lowered. At that time, in order to connect to the single core wire from the subscriber side, it is necessary to use a core wire conversion device that converts the tape core wire into a single core wire. There were also problems such as difficulty in making compact.
[0004]
In order to solve this problem, as shown in FIG. 8, optical fiber strands 1, 1,... It has been proposed to be configured so as to have both advantages as described above. That is, in this core wire, the optical fiber strands 1, 1... Are in a free state with the joint portion A where the optical fiber strands 1, 1. It has a structure in which non-bonded portions B are alternately provided. With this type of core wire, only the necessary strands can be drawn and the rest can be passed through, so it is possible to flexibly respond to concentrated / sparse demand, and without the need for a core conversion device. since the connection with the core wire becomes possible, have reduced and the transmission loss in the connecting portion, Hakare is compact closure further switching between core wire, the advantages such as disconnection can be easily performed [0005]
[Problems to be solved by the invention]
However, in such an optical fiber core wire, as is apparent from FIG. 9, there is a difference in thickness d between the coupling portion A and the non-coupling portion B, so that it can be stacked in the slot or to the bobbin (reel). When the core wires are laminated, such as during winding, there is a possibility that a side pressure is generated in the optical fiber on the non-coupling portion B side in the laminated portion of the coupling portion A and the non-coupling portion B (FIG. 10). Further, when the core wire is bent, such as when processing the extra length of the core wire in the closure or during bobbin (reel) winding, the bending stress is caused by the boundary between the coupling portion A and the non-coupling portion B as shown in FIG. There is a risk that the optical fiber will be damaged or deteriorated in characteristics due to the concentration in the step C and breaking in the shape of a dogleg. FIG. 12 schematically shows a state when the optical fiber core wire is subjected to the extra wire length processing in the closure 3.
[0006]
The present invention has been made to cope with such a point, and a coupling portion where optical fiber strands are coupled and a non-coupling portion where the optical fiber strands are in a free state are alternately provided. It has the features of a conventional multi-core core, and suppresses the side pressure on the optical fiber when the coupling part and non-coupling part overlap, and further bends to the boundary between the coupling part and non-coupling part. An object of the present invention is to provide an optical fiber cable using an optical fiber core wire that can alleviate stress concentration.
[0007]
[Means for Solving the Problems]
The present invention provides an optical fiber cable including a spacer in which a groove for accommodating an optical fiber core wire is formed on the outer periphery in an SZ twist, and a plurality of optical fiber strands arranged in parallel are provided in the groove of the spacer. The optical fiber strands are coupled to each other by an interval in the length direction, and the coupling material is provided between adjacent optical fiber strands in a range that does not substantially exceed the common tangent line of these optical fiber strands. The optical fiber cable is characterized in that a plurality of optical fiber cores are stacked and accommodated so that a non-bonded portion of each optical fiber core wire is positioned at the SZ inversion portion of the groove.
[0008]
[Action]
In the optical fiber core wire according to the present invention, since a coupling portion where a plurality of optical fiber strands are coupled and a non-coupling portion which is not coupled are alternately provided, a tape core wire and a single core wire are provided. In addition, since there is no difference in thickness between the coupling part and the non-coupling part, the side pressure on the optical fiber during lamination and winding can be suppressed, and the coupling part and the non-bonding part when bent The concentration of bending stress at the boundary with the coupling portion is alleviated, and bending of the optical fiber at the boundary at the time of processing the extra wire length in the closure or at the time of winding can be suppressed.
[0009]
【Example】
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a perspective view showing an optical fiber core wire used in an embodiment of the present invention.
[0010]
In FIG. 1, this optical fiber core 11 has four optical fiber strands 12 in which the outer periphery of the optical fiber 12a is coated with UV resin or the like 12b in parallel, and these optical fiber strands 12 are arranged in the length direction. It is the structure which couple | bonded with the coupling | bonding material 13 at intervals. That is, the coupling portion A in which the four optical fiber strands 12, 12... Are integrally coupled in a tape shape, and the uncoupled portion in which the four optical fiber strands 12, 12. It is set as the structure which provided B alternately. Then, as shown in the cross-sectional view of FIG. 2, in the coupling portion A, the four optical fiber strands 12, 12... Are filled in the valleys between these optical fiber strands 12, 12. They are bonded by a bonding material 13 such as UV resin.
[0011]
In the optical fiber core 11 configured as described above, the effect of providing the coupling portion A and the non-coupling portion B, that is, handling is easy, and high-density mounting of the optical fiber onto the cable by lamination is possible. In addition, since the optical fiber strands 12 can be individually taken out at the uncoupled portion B, only the required optical fiber strands 12 can be taken out and pulled down when being pulled down to the subscriber system. It is possible to respond flexibly to both concentrated demands and sparse demands, and further, the effect of reducing transmission loss at the connection part and making the closure more compact is possible because there is no need for a core converter. Is obtained. In addition, since there is no difference in thickness between the coupling part A and the non-coupling part B, as shown in FIG. 3, there is no unevenness in the length direction even if the optical fiber cores are laminated. Lateral pressure on the optical fiber during lamination and winding can be suppressed. Moreover, as shown in FIG. 4, even if it curves, the concentration of the bending stress at the boundary between the coupling part A and the non-coupling part B is alleviated, and the bending of the optical fiber can be suppressed. Therefore, as shown in FIG. 5, even if a compact core wire extra length process is performed on the optical fiber core 11 in the closure 14, the concentration of bending stress on the boundary portion is alleviated. Can be made smaller than before. In FIG. 5, reference numeral 15 denotes an aerial optical fiber cable using the optical fiber core wire 11.
[0012]
Next, an example of an optical fiber cable using the optical fiber core wire 11 will be described. As shown in FIG. 6, this optical fiber cable has a plurality of optical fiber cores 11 in each groove 16 of a spacer 17 in which a plurality of grooves 16 for accommodating optical fiber cores are formed in an SZ twist on the outer periphery. The uncoupled portions B of the optical fiber cores 11 are stacked and accommodated so as to be positioned at least in the SZ reversal portions 16a of the grooves 16. Further, although not shown, the presser winding And it is set as the structure which gave the sheath in order.
[0013]
In such an optical fiber cable, since each optical fiber 12 is in a free state at the SZ reversal portion 16a of the groove 16, the outer periphery of the optical fiber is covered all over the entire length. A large strain stress is not applied to the optical fiber 12 as in the case where a conventional tape core is accommodated, and a decrease in transmission characteristics of the optical fiber due to the strain stress can be suppressed.
[0014]
Note that the present invention is not limited to the four-core optical fiber as described in the above embodiment, and may have two, eight, or 16 cores. Further, the bonding material 13 does not need to completely fill the valleys between the optical fiber strands 12 arranged in parallel, the optical fiber strands 12 are coupled, and the common tangent of the optical fiber strands 12 is substantially reduced. It suffices if it is provided in a range that does not exceed the same, and the same effect can be obtained even if there are some irregularities.
[0015]
【The invention's effect】
As described above, the optical fiber of the present invention is a the coupling portion in which a plurality of optical fibers are coupled, uncoupled portions which are not bonded is provided on alternating structure, and, Since there is no difference in thickness between these coupling parts and non-coupling parts, it has the characteristics of tape cores and single cores, and can suppress the side pressure to the optical fiber during lamination and winding, The concentration of bending stress at the boundary between the joined part and the non-joined part when bent is alleviated. Moreover, in the optical fiber cable of the present invention, since each optical fiber is in a free state at the SZ inversion portion of the groove, no large strain stress is applied to the optical fiber, and the strain stress A decrease in transmission characteristics of the optical fiber can be suppressed.
[Brief description of the drawings]
FIG. 1 is a perspective view showing an optical fiber core wire according to an embodiment of the present invention.
FIG. 2 is a view showing a cross-sectional structure of a connecting portion A shown in FIG.
FIG. 3 is a perspective view showing a laminated state of optical fiber core wires according to an embodiment of the present invention.
FIG. 4 is a perspective view showing a state when an optical fiber core wire according to an embodiment of the present invention is bent.
FIG. 5 is a diagram schematically illustrating a process for extra length of a core in a closure of an optical fiber according to an embodiment of the present invention.
FIG. 6 is a side view showing a state in which the optical fiber core of one embodiment of the present invention is housed in a cable groove.
FIG. 7 is a perspective view showing an example of a conventional optical fiber core wire.
FIG. 8 is a perspective view showing another example of a conventional optical fiber core wire.
9 is a view showing a cross-sectional structure of a coupling portion A of the optical fiber core wire shown in FIG.
FIG. 10 is a perspective view showing a laminated state of conventional optical fiber core wires.
FIG. 11 is a perspective view showing a state when a conventional optical fiber core wire is bent.
FIG. 12 is a diagram schematically showing a state when a conventional optical fiber core wire is subjected to a surplus length processing in a closure.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 11 ......... Optical fiber core wire 12 ......... Optical fiber strand 12a ......... Optical fiber 12b ......... Coating | coating material 13 ......... Coupling material A ......... Coupling part B ......... Non-coupling part

Claims (1)

An optical fiber cable including a spacer in which a groove for accommodating an optical fiber core wire on the outer periphery is formed in an SZ twist,
A plurality of optical fiber strands arranged in parallel is coupled to the groove of the spacer by a coupling material at intervals in the length direction, and the coupling material is disposed between the adjacent optical fiber strands. A plurality of optical fiber cores provided within a range that does not substantially exceed the common tangent of the fiber strands are laminated so that the uncoupled portions of the optical fiber cores are positioned at the SZ inversion portion of the groove. An optical fiber cable characterized by being accommodated.

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