JPH10115755A - Optical fiber unit and optical cable formed by using the unit and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical cable with which the cost is low and the workability to take out coated fibers is good. SOLUTION: The optical fiber unit 1 which is provided with a rigid resin coating 9 in tight contact with the outer peripheries of a laminate of coated optical fiber ribbons 7 without adhesion thereto and has pliability and the hardness to the extent of breaking the coated optical fiber ribbons in the unit before damaging when the unit is bent to some extent or above is used. Supporting wires 13 are placed along such unit 1 and a sheath 15 having an hourglass shape in section is applied on the outer peripheries of the unit and the supporting wires 13. Since a grooved rod is not required, the cost is reduced. When the sheath 15 is peeled, the coated optical fiber ribbons 7 may be taken out by disassembling the rigid resin coating 9 with the fingertips.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical fiber unit suitable for a low-cost optical cable having a small number of optical fibers (100 or less), an optical cable using the same, and a method of manufacturing the same.

[0002]

2. Description of the Related Art A conventional optical cable uses a grooved rod having a one-way spiral groove or an SZ spiral groove formed on the outer periphery, and accommodates a laminated body of tape-shaped optical fiber core wires in the groove of the grooved rod. The so-called slot type is generally used. As an optical cable that does not use a grooved rod, a so-called loose tube type in which an optical fiber core wire is loosely accommodated in a tube and filled with jelly has been put to practical use.

[0003]

A slot type cable has a large number of optical fibers.
The price of the grooved rod per core is low and there is a price advantage, but for cables with less than 100 cores, the price of the grooved rod per core is high and the grooved rod is a barrier to cost reduction. ing. In the case of manufacturing a slot type cable, it is necessary to first manufacture a grooved rod, then drop the laminated optical fiber ribbon into the groove of the grooved rod and apply a sheath. However, there is a limit in reducing the manufacturing cost.

On the other hand, a loose tube type cable has an advantage that a cable with a small number of cores can be provided at low cost, but has a problem in workability at a cable laying site because the tube is filled with jelly. , Not very accepted in Japan.

In view of the above problems, an object of the present invention is to provide an optical fiber unit capable of forming a low-cost optical cable of a non-jelly type, an optical cable using the same, and a method of manufacturing the same.

[0006]

An optical fiber unit according to the present invention is provided such that a hard resin coating is provided in close contact with the outer periphery of a laminated body in which a plurality of tape-shaped optical fiber cores are laminated, without being adhered to each other. It is characterized in that the resin coating has flexibility and hardness enough to cause the tape-shaped optical fiber core wire to be broken before being damaged if it is bent to a certain degree or more.

In the conventional optical cable, the transmission loss is prevented from being increased by loosely housing the optical fiber core in a groove or a tube. However, this optical fiber unit employs a lamination of a tape-shaped optical fiber core. By tightly covering the body with a hard resin coating, the occurrence of microbending of the optical fiber is suppressed, and an increase in transmission loss is prevented.

When the laminated body of the tape-shaped optical fiber core is covered with a hard resin coating, the workability of taking out the tape-shaped optical fiber core becomes problematic.
It is in close contact with, but not adhered to, the laminate of tape-shaped optical fiber cores. It can be easily dismantled with your fingers.
Therefore, the workability of taking out the tape-shaped optical fiber is also good. Moreover, since the hard resin coating has flexibility, it can cope with bending of the optical fiber unit in a normal use state without any trouble.

Further, since the optical fiber unit of the present invention is provided with a hard resin coating, an optical cable can be formed by directly providing a sheath on the outer periphery thereof. Therefore, it is not necessary to use a grooved rod or the like, and cost can be reduced.

[0010] The degree of easiness of breaking of the hard resin coating is such that the hard resin coating does not break even if it is bent at a bending radius of 10 times or more of its outer diameter D.
It is desirable that the material be broken when bent with a smaller bending radius. In order to obtain such a hard resin coating, it is preferable to use a urethane acrylate-based ultraviolet or electron beam curable resin having a Young's modulus of 10 kgf / mm ² or more and a tensile strength of 1.0 kgf / mm ² or more. . The outer diameter D of the hard resin coating is preferably at least 1.1 times the diagonal length L of the cross section of the laminate of the tape-shaped optical fibers. This is because if the hard resin coating is too thin, the hard resin coating is easily damaged.

When the optical fiber unit of the present invention is used,
An optical cable can be constructed by directly applying a sheath to the sheath. When an optical cable is formed by using the optical fiber unit of the present invention, it is preferable to form a self-supporting optical cable in which a support line is provided along the optical fiber unit and a sheath having a gourd-shaped cross section is provided on the outer periphery thereof. .

[0012] Such a self-supporting type optical cable comprises a step of laminating a plurality of tape-shaped optical fiber cores and providing a hard resin coating on the outer periphery thereof to manufacture the optical fiber unit as described above, It can be manufactured by continuously performing a step of providing a unit with a supporting wire and applying a sheath having a gourd-shaped cross section to the outer periphery thereof. According to this manufacturing method, not only the grooved rod is not used but also the process from the optical fiber ribbon to the optical cable can be performed in a continuous process, so that the production efficiency is high and the cost can be reduced.

[0013]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows an embodiment of the optical fiber unit of the present invention. This optical fiber unit 1
Is a structure in which five tape-shaped optical fiber core wires 7 are laminated, and a hard resin coating 9 is provided on the outer periphery of the optical fiber core 7 without being bonded thereto. The tape-shaped optical fiber core 7 is formed by covering the four optical fiber strands 3 with the common coating 5 to form a tape. The hard resin coating 9 has flexibility and has such a hardness that if it is bent to a certain degree or more, the tape-shaped optical fiber core wire 7 is broken before being damaged.

The degree to which the hard resin coating 9 is easily broken depends on the
Although it does not break even if it is bent at a bending radius 10 times or more the outer diameter D,
Bends with a smaller bend radius
Is desirable. Such a hard resin coating 9 is made of urethane.
Acrylic UV or electron beam curable resin
Young's modulus 10kgf / mm^TwoAbove, tensile strength 1.0kgf
/ Mm ^TwoIt can be obtained by using the above resin
Wear.

In the embodiment shown in FIG. 1, the hard resin coating 9 has a Young's modulus of 10 kgf / mm ² or more and a tensile strength of 1.0 kgf / mm ^2.
When the above resin is used, this optical fiber unit 1
Was bent at a radius 10 times the outer diameter D, and no buckling disassembly occurred. On the other hand, the same size, the Young's modulus of less than 10 kgf / mm ² and the tensile strength of 1.0 kgf
/ Mm ² or more resin or Young's modulus 10kgf / mm
^In an optical fiber unit using a resin having a tensile strength of less than ² and a tensile strength of less than 1.0 kgf / mm ² , buckling occurred when bent at a radius 10 times the outer diameter D.

Therefore, using a resin having a Young's modulus of 10 kgf / mm ² or more and a tensile strength of 1.0 kgf / mm ² or more, in which buckling and disassembly did not occur under the above conditions, in the hard resin coating 9,
The presence or absence of buckling disintegration was investigated by changing the size and bending radius of the optical fiber unit, and the results were as shown in Table 1.

[0017]

[Table 1]

Therefore, it is preferable that the outer diameter D of the hard resin coating 9 is at least 1.1 times the diagonal length L of the cross section of the laminated body of the tape-shaped optical fiber cores 7 as shown in FIG. I understand. For example, as shown in FIG. 2, when there are five tape-shaped optical fiber cores 7, one tape-shaped optical fiber core 7
Has a thickness of 0.3 mm and a width of 1.1 mm, L =
1.9 mm and D ≧ 2.1 mm.

The optical fiber unit 1 of the present embodiment
Is that the hard resin coating 9 is in close contact with, but not adhered to, the laminate of the tape-shaped optical fiber cores 7, and that the tape-shaped optical fiber core 7 is not damaged when it is bent to a certain degree or more. Since it is hard enough to be broken, the hard resin coating 9 can be easily dismantled by folding it with fingers and peeling it off. Therefore, the workability of taking out the tape-shaped optical fiber core wire 7 is good.

Further, since the optical fiber unit 1 is provided with the hard resin coating 9, there is no fear that the transmission loss of the optical fiber is increased even if the outer sheath is directly provided with a sheath. An optical cable can be easily configured without using an optical cable. Therefore, an inexpensive optical cable can be obtained.

FIG. 3 shows a self-supporting optical cable 11 using the optical fiber unit 1 of FIG. The self-supporting type optical cable 11 has a configuration in which a support wire 13 such as a steel stranded wire is provided along the optical fiber unit 1 and a sheath 15 having a gourd-shaped cross section is provided on the outer periphery thereof. When such a self-supporting type optical cable 11 is configured, the cable main body 17 (the optical fiber unit 1 and the sheath 15) is meandered as shown in FIG. It is desirable to have an extra length for. In this way, when this cable is laid, there is no fear that the optical fiber unit 1 is laid with tension.

The optical cable 11 using the optical fiber unit 1 shown in FIG. 1 has a tape-shaped optical fiber core 7 and a hard resin coating 9 integrated with each other.
Are tightly integrated, the tape-shaped optical fiber 7 does not move in the optical cable 11, and therefore, there is no possibility that the tape-shaped optical fiber 7 protrudes at the end of the optical cable 1. . Further, if the sheath 15 is peeled off, the hard resin coating 9 can be broken and disassembled with fingers, so that it is easy to pull out an arbitrary tape-shaped optical fiber core 7 from the middle of the optical cable 11. Therefore, the optical cable 11 is suitable for a subscriber-type optical cable having many branches.

Next, an embodiment of a method of manufacturing a self-supporting optical cable according to the present invention will be described with reference to FIGS. In this manufacturing method, first, a required number of tape-shaped optical fiber core wires 7 are laminated, and the laminated body is passed through a die 21 to coat the outer periphery of the laminated body with a urethane acrylate ultraviolet curable resin. The uncured ultraviolet curable resin is supplied to the die 21 from the resin supply unit 23. The ultraviolet curable resin coated on the outer periphery of the laminate is irradiated with ultraviolet rays in the process of passing through the ultraviolet irradiation device 25 and is cured to form a hard resin coating 9. Thus, the optical fiber unit 1 is completed.

Next, the optical fiber unit 1 is guided by guide rollers 27A and 27B and introduced into the cross head 31 of the extruder 29. The support wire 13 is also introduced into the crosshead 31 in parallel with the optical fiber unit 1. A crosshead 31 is provided around the optical fiber unit 1 and the support wire 13.
Is covered with the sheath 15 having a gourd-shaped cross section, and the cable main body portion 17 and the support wire portion 19 are formed. The cable body 17 and the support wire 19 are connected to the sheath 15
Before being solidified, it is wound around a take-up speed setting capstan 33, and is cooled appropriately by water cooling or the like during one round with the capstan 33, and solidifies.

As shown in FIG. 6, the circumference of the capstan 33 around which the cable main body 17 is wound is larger than the circumference of the portion around which the support wire 19 is wound. Therefore, the cable main body 17 is taken up at a higher speed than the support wire 19. As a result, when the support wire portion 19 and the cable main body portion 19 exit the capstan 33 and are taken in a linear direction, the support wire portion 1
Because the cable body 17 is longer than 9
The cable body 17 comes to meander. After that, when it enters a water tank and is completely cooled, a self-supporting optical cable 11 as shown in FIG. 4 is obtained. A method for manufacturing a self-supporting optical cable in which the cable main body meanders relative to the support wire is known from Japanese Patent Application Laid-Open No. 8-75969.

In the manufacturing method of the present invention, the step of manufacturing an optical fiber unit and the step of providing a sheath having a gourd-shaped cross section on the outer periphery of the optical fiber unit along a support line are performed continuously. It has high productivity and has a remarkable effect on cost reduction of optical cables. The average transmission loss of the optical fiber cable (20 fibers) according to the present invention is 0.1
It was 9 dB / km (at λ = 1.55 μm).

[0027]

As described above, according to the present invention, since the hard resin coating is provided in close contact with the laminate of the tape-shaped optical fiber cores, the increase in transmission loss is small, and the resin coating is applied by hand. Thus, it is possible to obtain an optical fiber unit that can be disassembled to easily take out the optical fiber ribbon. When this optical fiber unit is used, an optical cable can be formed by directly applying a sheath to the outer periphery, so that the cost is low, there is no core wire protruding phenomenon at the end, and the branching of the tape-like optical fiber core from the middle. An easy optical cable is obtained. Further, the manufacturing method of the present invention can produce an optical cable from a tape-shaped optical fiber core in a continuous process, and thus has a remarkable effect in reducing the cost of the optical cable.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of an optical fiber unit of the present invention.

FIG. 2 is an explanatory view of a cross-sectional dimension of the optical fiber unit of FIG.

FIG. 3 is a sectional view showing an embodiment of the optical cable of the present invention.

FIG. 4 is a plan view showing a preferred embodiment of the optical cable of the present invention.

FIG. 5 is a plan view showing one embodiment of a method for manufacturing an optical cable of the present invention.

FIG. 6 is a sectional view of a capstan used in the manufacturing method of FIG. 5;

[Explanation of symbols]

 1: Optical fiber unit 7: Tape-shaped optical fiber core wire 9: Hard resin coating 11: Self-supporting optical cable 13: Support wire 15: Sheath 17: Cable body 19: Support wire 21: Dice 25: UV irradiation device 29 ： Extruder 31 ： Cross head 33 ： Capstan

Continued on the front page (72) Inventor Hideyuki Izukura 2-6-1 Marunouchi, Chiyoda-ku, Tokyo Furukawa Electric Co., Ltd. (72) Inventor Hideyuki Iwata 3-9-1-2 Nishishinjuku, Shinjuku-ku, Tokyo Japan Telegraph and Telephone Corporation

Claims (7)

[Claims] 1. A hard resin coating is provided in close contact with the outer periphery of a laminated body in which a plurality of tape-shaped optical fiber cores are stacked without bonding, and when the hard resin coating is flexible and bent to a certain degree or more. An optical fiber unit having such a hardness that a tape-like optical fiber core wire is broken before being damaged. 2. The hard resin coating is characterized in that it does not break even if it is bent at a bending radius of 10 times or more its outer diameter D, but has such a hardness that it is broken when bent at a bending radius smaller than that. The optical fiber unit according to claim 1. 3. The hard resin coating is a urethane acrylate ultraviolet or electron beam curable resin having a Young's modulus of 10 k.
The optical fiber unit according to claim 1, wherein the optical fiber unit is made of a resin having a gf / mm ² or more and a tensile strength of 1.0 kgf / mm ² or more. 4. The optical fiber according to claim 1, wherein the outer diameter D of the hard resin coating is at least 1.1 times the diagonal length L of the cross section of the laminate. unit. 5. An optical cable wherein the optical fiber unit according to claim 1 is directly provided with a sheath. 6. A self-supporting optical cable, wherein a support line is provided along the optical fiber unit according to any one of claims 1 to 4, and a gourd-shaped sheath is provided on the outer periphery thereof. 7. A method of manufacturing an optical fiber unit according to claim 1, wherein a plurality of tape-shaped optical fiber cores are laminated, and a hard resin coating is provided on an outer periphery thereof.
Providing a support line along the optical fiber unit and applying a gourd-shaped sheath to the outer periphery of the optical fiber unit.