JP4002237B2 - Fiber optic cable - Google Patents

Description

  The present invention relates to an optical fiber cable. In particular, the present invention relates to an optical fiber cable that can easily separate an optical fiber cable core from a sheath in a drop optical fiber cable and an indoor optical fiber cable.

  In order to be able to transmit and receive high-speed broadband information such as ultra-high-speed data in FTTH (Fiber to The Home), that is, home or office, an optical fiber cable core of an optical fiber cable extended by a trunk optical fiber cable is used. It is necessary to withdraw to ordinary houses. For this purpose, a drop optical fiber cable is used. Moreover, an indoor optical fiber cable is used for routing the optical fiber cable core drawn to a general house in a house or office.

Sectional views of the drop optical fiber cable and the indoor optical fiber cable are shown in FIGS. 6 (a) and 6 (b), respectively.
First, the drop optical fiber cable 1 shown in FIG. 6A is formed by integrally connecting an optical fiber cable body 10 and a support wire 6. The optical fiber cable main body 10 is provided with a pair of tensile strength members 5 made of, for example, steel wires on both sides of the optical fiber cores or the optical fiber core units 3 and 4, and these are collectively made of thermoplastic resin. It is comprised from what was coat | covered with the sheath 7. FIG. The support line 6 is connected to the sheath 7 and supports the optical fiber cable body 10. Here, reference numeral 2 denotes a plastic coating covering the optical fiber core units 3 and 4.

Further, the indoor optical fiber cable 1 ′ shown in FIG. 6B is composed only of the optical fiber cable main body 10. Similar to the drop optical fiber cable, the optical fiber cable main body 10 is provided with a pair of strength members 5 made of, for example, steel wires on both sides of the optical fiber core wire or the optical fiber core wire units 3 and 4. Are collectively covered with a sheath 7 of thermoplastic resin.
Note that polyvinyl chloride or polyethylene is generally used as the sheath 7 of the drop optical fiber cable 1 or the indoor optical fiber cable 1 '.

  When the drop optical fiber cable 1 and the indoor optical fiber cable 1 ′ are used to pull down the optical fiber cores or the optical fiber core units 3 and 4 and connect them to the O / E converter, the optical fiber cable main body The optical fiber core wire or the optical fiber core unit 3, 4 must be pulled out from the sheath 7 by tearing a part of the sheath 7 forming 10.

  Therefore, as shown in FIG. 6A, a notch 9 having a V-shaped cross section is formed in the optical fiber cable body 10 of the drop optical fiber cable 1 along the longitudinal direction (shown in FIG. 6B). The same applies to the indoor optical fiber cable 1 ′, and the description thereof will be omitted. In place of the V-shaped notch 9, there is a notch having a substantially isosceles trapezoidal cross section (see Patent Document 3).

  When the optical fiber core wire or the optical fiber core unit 3, 4 is pulled down, the sheath 7 is cut along the notch 9 if the sheath 7 of the optical fiber cable body 10 is torn. Thereby, the optical fiber core wire or the optical fiber core wire units 3 and 4 can be pulled out from the sheath 7.

  In particular, when the optical fiber cable body 10 is formed with a notch having a substantially isosceles trapezoidal cross section, when the sheath 7 is cut along the notch, the bottom portion of the notch is trapezoidal. Divided from the bottom part. Therefore, there is no possibility that the optical fiber core wire or the optical fiber core wire units 3 and 4 are left behind in one of the broken sheaths 7, and the optical fiber core wire or the optical fiber core wire units 3 and 4 can be easily pulled out from the sheath 7. Can do.

JP 2003-090943 A Japanese Patent Laid-Open No. 2003-140011 JP 2003-202471 A

  In the drop optical fiber cable 1 and the indoor optical fiber cable 1 ′ in which the notch 9 having a V-shaped cross section is formed along the longitudinal direction in the optical fiber cable main body 10 shown in FIGS. When stress concentrates on the bottom of the V-shape and a tear enters from the bottom, the sheath 7 is divided, but when the optical fiber cores or the optical fiber core units 3 and 4 are widely accommodated in the sheath 7 However, when the sheath 7 is divided into two, the optical fiber core wire or the optical fiber core wire units 3 and 4 remain in one sheath 7 and cannot be exposed. In such a case, the optical fiber core wire or the optical fiber core wire units 3 and 4 must be taken out of the sheath 7 by hand, but there is a high risk of damaging the core wire.

  The drop optical fiber cable 1 and the indoor optical fiber cable 1 ′ in which the notch 9 having a substantially isosceles cross section having a trapezoidal shape along the longitudinal direction is formed in the optical fiber cable body 10 can solve the above problem. There is a problem that the sheath 7 is difficult to be divided because stress is difficult to concentrate on the bottom portion of 9.

  The problem to be solved by the present invention is to provide an optical fiber cable in which the optical fiber core or the optical fiber core units 3 and 4 are easily exposed from the sheath 7 and the sheath 7 is easily cut off.

The invention according to claim 1 is an optical fiber cable in which one or more optical fiber cores or an optical fiber core unit in which optical fiber cores are bundled in parallel is covered with a sheath, and the sheath is an optical fiber cable. A thin-walled portion is formed in the longitudinal direction, and one or more notches are formed in the thin-walled portion, and the thin-walled portion is provided with a convex curve-shaped portion so as to be convex on the side opposite to the optical fiber core unit. The notch is provided at the end of the convex curve-shaped portion, the longest distance of the depth from the groove bottom of the notch to the side of the sheath is a, and the shortest distance from the groove bottom of the notch to the optical fiber core wire When the distance is b,
0.26 ≦ b / (a + b) ≦ 0.44 and b> 0.15 mm
And
When the shortest distance from the groove bottom of the notch to the optical fiber core is b and the longest distance from the thin portion to the optical fiber is c, c / b <1.5
And
When the width of the thin portion is d and the width of the optical fiber core unit bundled in parallel is w, d / w ≧ 0.45
It is characterized by being.

The invention according to claim 2 is the optical fiber cable of claim 1, wherein the notches are you characterized in that provided at both ends Sai portion of the convex curved shape portion.

The invention according to claim 3 is the optical fiber cable according to claim 1, wherein the notch
One of the ends of the convex curve shape part is extremely depressed, and the other part is almost completely depressed.
It is characterized by a shape that is not depressed or not depressed at all.

According to a fourth aspect of the present invention, in the optical fiber cable according to any one of the first to third aspects, the optical fiber core unit is composed of one or more tape cores .

The invention according to claim 5 is the optical fiber cable according to any one of claims 1 to 4, wherein a cross-sectional shape of the sheath of the cable body including the optical fiber core unit is substantially rectangular, and the notch Is formed on the long side of the sheath having a substantially rectangular cross section.

In the optical fiber cable according to claim 1, a thin portion is formed in the sheath, and 1 is formed in the thin portion.
The above notches are formed. Since one or more notches are formed, when the sheath is cut with the notch as a trigger, stress concentration occurs in the weakest notch formed in the thin-walled portion, where the sheath is intensively stretched and cut, so the sheath is divided It's easy to do. Further, the other notches are also relatively weak because they are formed in the thin wall portion. Therefore, it is easy to peel off the optical fiber core unit from the sheath.
In addition, by providing a convex curve-shaped part in the thin part, the part can be used for forming a notch, and the thin part
The part and the notch can be shaped efficiently.
Furthermore, the maximum depth from the groove bottom of the notch to the sheath side is a, and the optical depth from the groove bottom of the notch is
0.26 ≦ b / (a + b) ≦ 0.44 where b is the shortest distance to the Iva core unit.
It has become. Therefore, the force required for tearing the sheath can be reduced. Also
b> 0.15mm, so the bottom of the groove of the notch does not crack and is stable.
Scale production is possible.

Furthermore, in the optical fiber cable according to claim 1, when the shortest distance from the groove bottom of the notch to the optical fiber core unit is b and the longest distance from the thin portion to the optical fiber core unit is c, c / b <1.5. Therefore, when the sheath is torn, the convex portion at the bottom of the groove is also extended, and the take-out property of the core wire is improved.
Further, when the width of the thin portion is d and the width of the optical fiber unit housed below the bottom of the groove is w, d / w ≧ 0.45 is satisfied, so that the width of the thin portion is sufficient. It is possible to effectively suppress the fiber core unit from being left in the sheath.

In the optical fiber cable according to the fourth aspect , since the optical fiber core unit is composed of one or more tape cores, it is effective for increasing the number of optical fiber cables. In addition, since the optical fiber core unit is easily peeled off from the sheath, it is possible to suppress a problem that the coating material for the tape core wire is peeled off from the optical fiber due to the use of the tape core wire.

An optical fiber cable according to claim 5, wherein the cable includes the optical fiber core unit.
The cross-sectional shape of the sheath of the main body is substantially rectangular, and the notch is formed on the long side of the sheath having a substantially rectangular cross section. Here, since the notch is formed on the long side of the sheath, it is easy to tear the sheath by using the notch.

The optical fiber cable according to the present invention is used as, for example, an indoor optical cable.
A sectional view of the indoor optical cable of the reference example is shown in FIG. The indoor optical cable 1 ′ shown in FIG. 1 is composed only of an optical fiber cable body 10.

Here, the characteristic of the optical fiber cable according to the present invention resides in the optical fiber cable body 10, and this will be described with reference to FIG.
The optical fiber cable main body 10 is provided with a pair of strength members 5 made of, for example, steel wires as needed on both sides of the optical fiber core units 3 and 4 in which the optical fiber core wires or the optical fiber core wires are bundled in parallel. These are constituted by being collectively covered with a sheath 7 of thermoplastic resin. The optical fiber core units 3 and 4 may be made of one or more tape cores. Here, reference numeral 2 denotes a plastic coating covering the optical fiber core units 3 and 4.

The sheath 7 of the optical fiber cable main body 10 of the optical fiber cable according to the present invention is formed with a thin portion in the longitudinal direction of the optical fiber cable. One or more notches 11 and 12 are formed in the thin portion 9.
For example, the thin-walled portion 9 includes a convex curve-shaped portion as shown in FIG. 2 so that both ends of the curve constitute notches 11 and 12, respectively.
A specific cross-sectional shape of the sheath 7 is, for example, a substantially rectangular shape, and the notches 11 and 12 formed in the thin portion 9 of the sheath 7 are formed on the long side of the substantially rectangular shape.
FIG. 1 shows an indoor optical cable 1 ′ in which the thin-walled portion 9 is linear and the notches 11 and 12 are in the middle.

  The best mode recognized by the inventors for carrying out the present invention will be described below. FIG. 2 is a cross-sectional view showing one embodiment of the present invention. The optical fiber cable shown in FIG. 2 is configured as an indoor optical fiber cable 1 ′ composed only of the optical fiber cable body 10.

  In the optical fiber cable main body 10, a pair of tensile strength members 5 made of FRP having a diameter of 0.4 mm are attached to both sides of the optical fiber core units 3 and 4 in which the optical fiber cores are bundled in parallel, and these are collectively. The long side dimension is 4 mm, and the short side dimension is 2 mm, which is covered with a substantially rectangular non-halogen flame retardant polyethylene sheath 7 having a cross-sectional shape.

  The optical fiber core units 3 and 4 further cover the cores coated with an ultraviolet curable resin so as to have an outer diameter of 250 μm on a quartz fiber strand having a diameter of 125 μm, and further cover the four cores with an ultraviolet curable resin tape coating material. Two tape cores constituting a four-core tape core having a width w = 1.1 mm and a thickness of 0.32 mm are laminated.

  A thin portion 9 is formed in the sheath 7 of the optical fiber cable body 10 in the longitudinal direction of the optical fiber cable. In the optical fiber cable 1 according to the present embodiment, the thin portion 9 has a convex curve shape, and both ends of the curve constitute a notch A11 and a notch B12, respectively.

  Here, the width of the opening is 1 mm. The width of the thin portion is d = 0.5 mm, and is opposed to a region of about 45% of the width w of the optical fiber core units 3 and 4. The distance relationship between the sheath 7 jacket, the groove bottom of the notch A11 (notch B12), and the optical fiber core units 3 and 4 is a = 0.38 mm (the longest distance from the groove bottom of the notch to the side of the sheath) ), B = 0.3 mm (the shortest distance from the groove bottom of the notch to the optical fiber core), and c = 0.35 mm (the longest distance from the thin portion to the optical fiber core).

In the optical fiber cable 1 of this embodiment, when the sheath 7 is torn, one of the relatively weak notches (for example, the notch A11) is extended (broken line portion) as shown in FIG. While being away from the fiber core units 3 and 4, and the convex curve portion sheath (straight portion) is slightly stretched, the fiber core units 3 and 4 tend to be peeled off by the notch B12.
As a result, the optical fiber core units 3 and 4 can be reliably separated in the center at the time of sheath tearing, and it is possible to suppress damage such as peeling of the tape coating material of the optical fiber core units 3 and 4. it can.
Furthermore, when the sheath 7 is torn, stress concentrates on the relatively weak notch A11, so that the sheath can be torn with a relatively weak force.

  Here, with respect to the optical fiber cable 1 of the present embodiment, the gap between the notch A11 and the notch B12 is improved in order to improve the tearability when the sheath 7 is torn and the ease of taking out the optical fiber core units 3 and 4 from the sheath 7. d, Optimization of distance relations a, b, and c between the sheath 7 jacket, the groove bottoms of the notches A11 and B12, and the optical fiber core units 3 and 4. The results are shown in Table 1.

From the above, the sheath 4 in which 0.26 ≦ b / (a + b) ≦ 0.44 and b> 0.15 mm, and c / b <1.5 and d / w ≧ 0.45 are favorable. It was found that the conditions for satisfying the tearability of the wire, the take-out properties of the core units 3 and 4, and the manufacturability were satisfied.

  In this embodiment, it is an indoor optical fiber cable 1 ′ composed of only the optical fiber cable body 10. However, as shown in FIG. 4, the optical fiber cable body 10 and the support wire 6 are integrally connected. The drop optical fiber cable 1 may be used.

  In this embodiment, as shown in FIG. 2, the depths at which the bottom grooves of the notches A11 and B12 drop are substantially the same, but as shown in FIG. 5, both ends of the convex curve portion at the groove bottom of the notch The shape may be such that one is extremely depressed and the other is hardly depressed or not depressed at all.

  The strength member 5 is not limited to FRP but may be a steel wire, fiber, or the like. Further, the strength member 5 may not be provided. Furthermore, the optical fiber may be made of plastic as well as quartz. The number of cores and the number of stacked cores of the optical fiber core unit can be appropriately selected. Further, not only the tape core wire but also a plurality of optical fiber core wires twisted or appropriately disposed in the sheath 7 may be used.

  The cross-sectional shape of the sheath 7 can be appropriately selected to be elliptical or polygonal, and the material of the sheath 7 can also be appropriately selected from polyvinyl chloride, polyethylene, non-halogen flame-retardant polyethylene, and the like. Further, the shape of the thin portion and the number of notches can be changed as appropriate.

It is sectional drawing of the optical fiber cable of a reference example . It is sectional drawing of the optical fiber cable which concerns on embodiment of this invention. It is sectional drawing of the state which has cut | disconnected the sheath of the optical fiber cable which concerns on embodiment of this invention. It is sectional drawing of the optical fiber cable which concerns on the other embodiment of this invention. It is sectional drawing of the optical fiber cable which concerns on further another form of implementation of this invention. It is sectional drawing of the optical fiber cable which concerns on a prior art, (a) is a drop optical fiber cable, (b) is an indoor optical fiber cable.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Drop optical fiber cable 1 'Indoor optical fiber cable 2 Plastic coating 3 Optical fiber core unit 4 Optical fiber core unit 5 Tensile wire 6 Support wire 7 Sheath 9 Thin part 10 Optical fiber cable body 11 Notch (A)
12 Notch (B)

Claims (5)

An optical fiber cable in which one or more optical fiber cores or an optical fiber core unit in which optical fiber cores are bundled in parallel is covered with a sheath, the sheath having a thin portion formed in the longitudinal direction of the optical fiber cable The thin-walled portion is formed with one or more notches, and the thin-walled portion is provided with a convex curve-shaped portion so as to be convex on the side opposite to the optical fiber core unit, and the notch has the convex curve Provided at the edge of the shape part,
When the longest distance of the depth from the groove bottom of the notch to the side of the sheath is a, and the shortest distance from the groove bottom of the notch to the optical fiber core wire is b,
0.26 ≦ b / (a + b) ≦ 0.44 and b> 0.15 mm
And
When the shortest distance from the groove bottom of the notch to the optical fiber core is b and the longest distance from the thin portion to the optical fiber is c, c / b <1.5
And
When the width of the thin portion is d and the width of the optical fiber core unit bundled in parallel is w, d / w ≧ 0.45
An optical fiber cable characterized by being. Claim 1 wherein the notch, characterized in that are provided at both ends Sai portion of the convex curved shape portion
The optical fiber cable described. One of the notches is extremely depressed at both ends of the convex curve-shaped portion, and the other
If you are in a shape that is hardly depressed or not depressed at all
The optical fiber cable according to claim 1. The optical fiber core unit is composed of one or more tape core wires.
The optical fiber cable according to any one of claims 1 to 3. The cross-sectional shape of the sheath of the cable body containing the optical fiber core unit is substantially rectangular, and the notch is formed on the long side of the sheath having a substantially rectangular cross section. The optical fiber cable as described in any one of 1-4.

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