JP4263680B2 - Self-supporting retractable optical cable - Google Patents

Description

  TECHNICAL FIELD The present invention relates to a self-supporting optical fiber cable for use in a FTTH (Fiber To The Home) optical communication network, which effectively protects optical fiber core wires from insect damage such as moths and birds and beasts such as squirrels and crows. Can be protected.

A conventional self-supporting lead-in optical cable is, for example, as shown in FIG. 4 and includes a cable sheath that includes one or a plurality of optical fiber cores f and strength members R for optical elements arranged on the left and right sides thereof. It consists of a long optical element part E coated with C ₁ and a covering C ₂ of a support wire S parallel to the strength members R, R through a neck part m. A V notch N is formed vertically on both sides of the optical fiber core line f against the outer surface of the sheath C ₁ , that is, the outer surface parallel to the line connecting the strength members R and R. The V-notch N is one in which the cable sheath C ₁ and 2 divided by longitudinally to expose the optical fiber f in the middle and can be taken out easily the optical fiber.

  In the conventional self-supporting optical fiber for joining and drawing in, the spear pierces the egg-laying tube at the portion of the V notch N, damages the optical fiber core f, and as a result, the transmission efficiency of the optical fiber core f is significantly impaired. An accident has occurred. This is because the spider easily pierces the egg-laying tube at the bottom of the V-notch N, and the bottom of the V-notch N and the optical fiber core f are close to each other. This is because the possibility of reaching the optical fiber core line f toward the core line f is high. And it is reported that many such accidents occur with the spread of FTTH, and countermeasures against this problem are required.

If the V notch N provided in the cable sheath C ₁ is eliminated, the possibility that the laying tube pierced by the cable sheath C ₁ reaches the optical fiber core line f and is damaged becomes small. Further, when the optical fiber core is a self-supporting optical fiber for pulling-in with a tape core as in the example of FIG. 5 (Japanese Patent Laid-Open No. 2003-90942), the laid egg-laying tube is an optical fiber. The possibility of reaching the core line f and damaging it is not small. Accordingly, it has been invented to protect the optical fiber core f from insect damage and the like by vertically attaching protective tapes on both sides of the tape core and sandwiching the optical fiber core f from the front and back (Prior Art). And the invention according to Japanese Patent Application No. 2004-258042.
JP 2003-90942 A Japanese Patent Application No. 2004-258042

According to the above prior art, the optical fiber core wire is prevented from being damaged by the spawning tube of the spider, but since the protective tape is interposed as described above, the optical fiber core wire f is used for branching, connection, etc. It cannot be easily and easily removed.
Therefore, the object of the present invention is to devise the structure of the optical element portion E so that the cable sheath can be easily divided and the optical fiber core wire f can be taken out even if the V-notch is eliminated from the self-supporting retractable optical cable. That is.

[Solution 1]
Means for solving the above-mentioned problem comprises a long optical element portion E in which a tape-shaped optical fiber core f is covered with a cable sheath C1, and a coating C2 of a support wire S parallel to the optical fiber core f. In the optical cable for self-supporting pull-in integrated with the cable sheath C1, the following (A) to (C) are performed.
(A) Optical fiber cores are vertically attached with protective tapes functioning as tensile strength materials to protect the optical fiber cores from piercing of spider spawning tubes and rodent attacks on both sides of the optical fiber core Pinch
(B) A tear string that also functions as a tensile strength material is attached vertically to both ends in the width direction of the optical fiber core,
(C) The cable sheath is divided into the front side and the back side by tearing both ends of the cable sheath C1 of the optical element portion E in the width direction, which is the same direction as the width direction of the optical fiber core wire, with the tear string. The optical fiber core wire f is exposed.

[Action]
There is no V notch on the surface of the cable sheath of the optical element part E (see FIG. 1), and protective fiber is vertically attached to both the front and back sides of the optical fiber core so that the optical fiber core is sandwiched. Even if the piercing sticks, it is reliably prevented by the protective tape t (see the metal tape t in FIG. 1) that the tip thereof reaches the optical fiber core f.
When the outer end in the width direction of the cable sheath C ₁ of the optical element portion E is cut with a cutter and the tear string T attached vertically adjacent to the optical fiber core line f is pulled outward, the width of the cable sheath C ₁ The outer end in the direction is torn laterally, the cable sheath C ₁ is separated into the front side and the back side, and the protective tape t and the optical fiber core wire f are exposed. Therefore, the optical fiber core wire f can be easily taken out. .
Since the tear string T is a high-strength wire, it also functions as a tensile material, and the protective tape t also functions as a tensile material, so that the optical element portion E has high tensile strength. Accordingly, there is no possibility that a large tension acts on the optical fiber core line f due to the tension applied to the optical element portion E and the transmission efficiency is not impaired.

[Solution 2]
The solution 2 is that the solution tape ₁ is bonded to the inner surface of the cable sheath C ₁ via the hot-melt adhesive layer.
[Action]
The protective tape is bonded and integrated with the inner surface of the cable sheath via a hot melt adhesive layer, and the thermal expansion coefficient of the protective tape is smaller than that of the cable sheath. There is an inhibitory effect. Therefore, a decrease in the transmission efficiency of the optical fiber ribbon due to the thermal expansion and contraction of the cable sheath is suppressed, and the transmission efficiency is stabilized against a temperature change.

[Embodiment 1]
The embodiment 1 is that the solution tape 1 is a stainless steel tape having a thickness of 0.1 mm.
[Embodiment 2]
In the second embodiment, the hot melt adhesive film is laminated on the protective tape with respect to the solution 2, and when the cable sheath is extruded, the hot melt adhesive film is melted and the protective tape is adhered to the inner surface of the cable sheath. It is to have been made.
[Embodiment 3]
Embodiment 3 is that the tear string of the solution 1 is a 1000 denier tensile wire made of aramid fiber.

Since the invention according to Solution 1 is based on the above solution, the above operation can be achieved and the above-mentioned problem can be completely solved. In other words, the V-notch is abolished, and the optical fiber core wire is easily and easily taken out for branching, connection, etc. while the optical fiber core wire is sandwiched from the front and back with a protective tape to prevent damage caused by wrinkles. be able to.
Also, since the optical fiber ribbon is sandwiched by protective tapes from both front and back sides, the optical fiber tape is protected from attacks by rodents such as squirrels and birds such as crows. It is possible to reliably avoid damage to the cores by birds and beasts.

The invention according to Solution 2 is that in which the protective tape is bonded to the inner surface of the cable sheath by the hot melt adhesive layer, and the protective tape has a smaller coefficient of thermal expansion than the cable sheath. Expansion and contraction due to temperature changes is suppressed by the protective tape.
Therefore, a decrease in the transmission efficiency of the optical fiber core due to the temperature change is suppressed, and the transmission efficiency is stabilized regardless of the temperature change.

Next, an embodiment will be described with reference to FIG.
In this embodiment, a stainless steel metal tape t having a thickness of 0.1 mm is vertically attached to the upper and lower sides of a ribbon-shaped (tape-shaped) optical fiber core f made of four optical fibers. laminating a film made of hot melt adhesive to a surface contacting the cable sheath C ₁ of t, and then fusing the stainless metal tape t to the cable sheath C ₁ by using this. The cable sheath C ₁ and the covering C ₂ of the support wire S are connected to each other through the neck m.
The tear string T is an about 1000 denier tensile wire made of aramid fiber, and the cable sheath C ₁ is made of flame retardant polyethylene.
In addition, a steel or aluminum alloy tape can be used as the metal tape t. When the protective tape is made of a non-metallic material, it is necessary to use a material that can withstand attacks from rods and rodents and has excellent tensile strength, and an FRP plate or the like is suitable.
The optical element portion E has a thickness of about 2.5 mm and a width of about 6 mm. On the other hand, the support wire S is a steel wire having a wire diameter of 1.2 mm.

  As a result of investigating the characteristics of the optical cable of this example, the transmission loss in the transmission with the measurement wavelength of 1.55 μm is 0.25 dB / km or less, and it was confirmed that it has the same performance as the conventional optical fiber cable. Moreover, it was confirmed that the transmission loss change in the transmission by the same measurement wavelength is 0.05 dB / km or less with respect to the temperature change in the range of −30 ° C. to + 70 ° C.

Moreover, the penetration test of the rodent simulated tooth needle (rodent simulated tooth) shown in FIG. 3 was performed, and it was confirmed that there was no damage such as disconnection in the optical fiber.
The simulated tooth needle (simulated tooth) n used for the penetration test of this simulated tooth needle is shown in FIG. 2 and is made of steel with a sharp tip with a steel wire having a wire diameter of 1 mm slanted in a range of 2 mm in length. It is a needle.
The left and right sides of the optical cable of the embodiment of FIG. 3 are fixed with left and right press plates (interval width 10 mm), and the simulated tooth needle n is pierced in a vertical direction with a static load of 30 N. The change in the transmission efficiency of the fiber was measured, and it was confirmed that the optical fiber was not damaged.

These are sectional drawings which show roughly the solution means 1 of this invention. These are the top view and side view of the simulation tooth | gear used in the penetration test of the simulation tooth needle (simulation tooth). It is a schematic diagram which shows the state of the penetration test of a simulated tooth needle. FIG. 3 is a sectional view of a conventional self-supporting lead-in optical cable. FIG. 6 is a cross-sectional view of another conventional self-supporting lead-in optical cable.

Explanation of symbols

C ₁ ... Cable sheath C ₂ ... Covering support wire E ... Optical element part f ... Optical fiber core wire N ... V notch n ... Simulated tooth needle (simulated tooth)
R ... Strength body S ... Support wire T ... Tear string t ... Protective tape (metal tape)
m ... neck

Claims (5)

The tape-shaped optical fiber core f is composed of a long optical element portion covered with a cable sheath C1, and a covering C2 of a support wire S parallel to the optical fiber core wire f is integrated with the cable sheath C1. In the self-supporting retractable optical cable
A protective tape functioning as a tensile strength material is vertically attached to both the front and back sides of the optical fiber to protect the optical fiber from piercing of the spawning tube and rodent attack. And
Attach a tear string that also functions as a tensile material to both ends in the width direction of the optical fiber core, and attach it vertically.
The cable sheath C1 of the optical element section is split into a front side and a back side by tearing both ends in the width direction, which is the same direction as the width direction of the optical fiber core wire, with the tear string. A self-supporting lead-in optical cable in which the fiber core wire f is exposed.   2. The self-supporting lead-in optical cable according to claim 1, wherein the protective tape is adhered to the inner surface of the cable sheath C1 through a hot-melt adhesive layer.   2. The self-supporting lead-in optical cable according to claim 1, wherein the protective tape is a stainless steel tape having a thickness of 0.1 mm.   The hot-melt adhesive film is laminated on the protective tape, and when the cable sheath C1 is extruded, the hot-melt adhesive film is melted to adhere the protective tape to the inner surface of the cable sheath C1. Self-supporting retractable optical cable.   The self-supporting lead-in optical cable according to claim 1 or 2, wherein the tear string is a 1000 denier tensile wire made of aramid fiber.

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