JPH04253008A - High-density optical fiber cable - Google Patents

Abstract

PURPOSE:To provide the optical fiber cable which is used for optical communication, etc., and has stabler characteristics, higher reliability, smaller diameter, and higher density. CONSTITUTION:Plural sheets of coated tape optical fibers 1 which are arrayed with plural pieces of coated optical fibers 11 in parallel and are integrated by applying integral sheathing thereon and a buffer layer 21 consisting of a silicon gel and a protective layer 22 consisting of a thermoplastic resin are provided on the outer side thereof, by which the increase in the loss rate by a side pressure is lessened when such coated optical fibers are used as the constituting elements of the cable. Then, the finer size and higher density of the optical fiber cable are obtd.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to optical fiber cables used in optical communications, and more particularly to the structure of high-density optical fiber cables with stable characteristics and high reliability.

0002

2. Description of the Related Art FIGS. 4 and 5 are cross-sectional views of examples of the structure of a conventional optical fiber cable of the tape core assembly type. Further, FIG. 6 is a cross-sectional view of an example of an optical fiber ribbon used in the above-mentioned cable.

FIG. 4 shows a slot type optical fiber cable.
A slotted rod (102) with a plurality of slots (102a) formed on the outer periphery and a high tensile strength body (103) in the center.
A laminate in which a plurality of optical fiber ribbons (101) are stacked is housed in the slot (102a).

[0004] The slot rod (102) is made of a plastic material, and the slot (102a) has a rectangular cross section in order to accommodate the stack of optical fiber tapes (101) at high density without any disorder. It also extends in a spiral or SZ shape in the length direction.

A pressure tape (104) is provided on the outer periphery of the slot rod (102), and an outer coating layer (105) formed by extrusion molding of a plastic material such as polyethylene is provided on the outside of the tape (104). There is.

FIG. 5 shows a composite pipe (LAP pipe) (10
6) Inside, a plurality of optical fiber tape cores (101)
A plurality of LAP pipe units (110) containing
) are twisted on the circumference of the tension member (107) provided with
105).

The optical fiber tape (Figure 6) used in these cables consists of a plurality of coated optical fibers with a soft inner layer and a hard outer layer formed on an optical fiber with an outer diameter of 125 μm. The outside is covered all at once and integrated into a tape shape.

[0008]

[Problem to be solved by the invention] Recently, there has been an increasing demand for multi-core and high-density optical fiber cables, and in order to achieve this, it is necessary to reduce the diameter of optical fiber cores and optical fiber units. This is an extremely important issue. However, it has been difficult to reduce the diameter of the conventional optical fiber cables mentioned above.

That is, in a tape fiber assembly type optical fiber cable, the optical fiber tape core is housed directly in a slot or LAP pipe, but the optical fiber tape core and the inner wall of the slot or the inner wall of the LAP pipe are directly connected to each other. Since force is applied to the optical fiber ribbon when they come into contact, the optical fiber used must have lateral pressure resistance characteristics, and it is necessary to use an optical fiber ribbon with a relatively thick coating. Since it is necessary to provide a sufficient distance between the optical fiber ribbon and each inner wall surface, it has been difficult to reduce the diameter of the optical fiber unit.

0010

[Means for Solving the Problems] The present invention provides a high-density optical fiber cable that solves the above-mentioned problems.
The feature is that multiple optical fiber ribbons are stacked together by arranging multiple optical fibers in parallel and applying a bulk jacket, and the outside is covered with a buffer layer of silicone gel and thermoplastic resin. A high-density optical fiber tape core unit provided with a protective layer according to the present invention is used as a component of the cable.

[0011]

[Function] Optical fiber tape, which is made by arranging optical fibers in parallel, is vulnerable to external forces such as lateral pressure. In comparison, it is necessary to make it sufficiently large so that it is not susceptible to lateral pressure, etc., which makes it difficult to reduce the diameter of the optical fiber unit or optical fiber cable.

In order to solve this problem, the present invention provides a high-density tape core unit by providing a buffer layer made of silicone gel with a cushioning effect and a protective layer made of thermoplastic resin on the outside of the laminate of optical fiber tape cores. By configuring this, it is possible to achieve high density optical fiber cables.

In the case of the present invention, the optical fiber unit is shown in FIG.
Even when the optical fibers are assembled around the central tension member as in the example shown in FIG. No increase in transmission loss occurs.

[0014] Furthermore, since the unit has an integrated stack of optical fiber ribbons, no arrangement disorder occurs and no clearance is required for movement of the optical fiber tapes.

[0015] The high-density optical fiber tape core unit is
Since the optical fiber tape core laminate is integrated, there seems to be a problem that it is difficult to remove the tape core. As shown in 2 (b), the protective layer (2
This can be easily solved by taking measures such as inserting a linear or spiral notch (23) in 2), or inserting one or more tearing strings (24).

[0016] Furthermore, the unit can be easily identified by coloring the surface of the protective layer of the unit or by coloring the protective layer itself.

[0017]

[Example] Fig. 1 is a cross-sectional view of an embodiment of the high-density optical fiber cable of the present invention, Fig. 2 (a) is a cross-sectional view of an example of the optical fiber ribbon used therein, and Fig. 2 (b) is a cross-sectional view of an example of the optical fiber ribbon used therein. FIG. 3 is a cross-sectional view of an example of a density tape core unit.

In this example, as shown in FIG. 2(A), a 125 μm Ge-SM optical fiber (12) is used.
A soft inner layer with a Young's modulus of 0.2 kg/mm2 (1
3) and a hard outer layer with a Young's modulus of 50 kg/mm2 (
Eight thin optical fiber core wires (11) with an outer diameter (d) of 0.18 mmφ and thinly applied with 14) are arranged in parallel and integrated with a thin tape material (15), resulting in a thickness (t) of approximately 0. .18mm,
Thin diameter tape optical fiber core wire with width (w) = 1.4 mm (
1) was used. Eight thin-diameter optical fiber ribbons (1) are laminated, and a relatively soft buffer layer (21) made of silicone gel and a protective layer (22) made of relatively hard thermoplastic resin are applied to the outside. A high-density tape core unit (2) as shown in Figure 1 was constructed. At this time, both twisted and untwisted laminates of the thin optical fiber tape (1) were prepared.

The silicone gel of the present invention forming the buffer layer (21) is not particularly limited as long as it has a penetration degree (1/10 mm) of about 50 to 400 as defined by JIS K 2220, but it can be processed Due to its properties, an addition reaction type in which gelation occurs through the reaction of -SiCH=CH2 and Si-H in the presence of a catalyst such as platinum is desirable.

Nylon, PBT, polycarbonate, etc. can be used as the thermoplastic resin protective layer in the present invention, but there is no particular restriction as long as it can be melt-extruded onto a pipe using an extruder.

The buffer layer made of silicone gel and the protective layer made of thermoplastic resin of the present invention can be formed in separate manufacturing processes, but since the buffer layer is very soft and easily destroyed, it is not possible to form them in a continuous process. desirable. For example, using a method generally referred to as loose tube extrusion, a pipe-shaped coating of thermoplastic resin is formed around the laminated optical fiber tape cores, and the laminate of the tape cores is formed through the crosshead of an extruder. It is possible to use a method such as injecting uncured silicone gel between the pipe-shaped coating and heating it to a temperature below the melting point/curing point of the thermoplastic resin to gel it.

As shown in FIG. 1, a plurality of the high-density fiber units (2) are formed into a tension member (3) in which a polyethylene layer (32) is provided on the outer periphery of a steel wire (31) that is a high tensile strength body. Twist around the
Further, an outer covering layer (5) formed by extrusion molding of a plastic material such as polyethylene was provided on the outside thereof.

[0023] Note that the high-density tape core unit (2
) may be twisted in the same direction or may be twisted in SZ. Further, the tension member is not limited to steel wire, but may also be a high tensile strength member coated with plastic.

FIG. 3 is a cross-sectional view of another embodiment of the high-density fiber cable of the present invention. As shown in the figure, a slot rod (6) made of plastic, for example, has a high tensile strength body (7) at the center and a plurality of slots (6a) with fan-shaped cross-sections on the outer periphery. , Figure 2
A plurality of high-density tape fiber units (2) shown in (b) are each housed. A pressure wrapping tape (4) is applied on the outer periphery of the slot rod (6), and an outer coating layer (5) is further provided thereon.

[0025]

[Effects of the Invention] In fabricating the cable shown in Figure 1, a small-diameter optical fiber core wire was used, so in the bobbin-wound state after drawing and in the bobbin-wound state after tape-making, the loss value of the optical fiber due to lateral pressure was reduced. Although the loss was high, we confirmed that if we took the sample and put it in a state without lateral pressure, the loss would be the same as that of a normal optical fiber, so we proceeded to the process of unitizing it.

The loss value of the optical fiber after unitization was good, and it was confirmed that the structure of the present invention is effective in improving the lateral pressure characteristics of the small diameter optical fiber ribbon.

[0027] The process was further advanced, and the high-density tape core unit was twisted on the outer periphery of the polyethylene-coated steel wire, a presser tape was applied thereon, and an outer coating layer was applied. There is no change in the loss value at all,
It was confirmed that the handling during manufacturing was also good.

[0028] The mechanical properties and temperature properties of the prototype cable were also measured, and it was confirmed that the cable had good properties at -40°C, except for a slight increase in loss value, and there were no problems in practical use. As described above, by using the high-density tape core unit of the present invention, it was possible to achieve thinning of the high-density optical fiber cable with stable characteristics and high reliability.

For example, for conventional cables, the limit was 200 fibers and 21 mmφ for the structure shown in FIG. 4, and 21 mmφ for 200 fibers for the structure shown in FIG. In the case of 400 cores, 17mmφ
I was able to fit it within the outer diameter of .

[0030] Compared with the conventional structure, the effects of higher density and thinner wires are noticeable.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of an embodiment of a high-density fiber optic cable of the present invention.

FIG. 2(a) is a cross-sectional view of a small-diameter optical fiber tape core, and FIG. 2(b) is a cross-sectional view of a high-density tape core unit.

FIG. 3 is a cross-sectional view of another embodiment of the high-density optical fiber cable of the present invention.

FIG. 4 is a cross-sectional view of a structural example of a conventional optical fiber tape fiber cable assembly type optical fiber cable, showing a slot type.

FIG. 5 is a cross-sectional view of a structural example of a conventional optical fiber tape bundled optical fiber cable, showing a composite pipe type.

FIG. 6 is a cross-sectional view of an example of an optical fiber ribbon used in a conventional cable.

[Explanation of symbols]

1 Small-diameter optical fiber tape coated wire 11 Small-diameter optical fiber coated wire 12 Optical fiber 13 Primary coating layer 14 Secondary coating layer 2 High-density tape coated unit 21 Buffer layer 22 Protective layer 23 Notch 24 Tear-off string 3 Tension member 31 High tensile strength body 32 Plastic coating 4 Pressure wrapping tape 5 External coating layer 6 Slot rod 7 High tensile strength body 101 Optical fiber tape core 101a UV resin coated optical fiber core 101b
Collective coating layer 102 Slot rod 102a Slot 103 High tensile strength body 104 Pressure winding tape 105 External coating layer 106 Composite pipe 107 Tension member 107a High tensile strength body 107b Plastic coating layer 110 LAP pipe unit

Claims (1)

[Claims] Claim 1: A high-density ribbon ribbon consisting of a plurality of optical fiber ribbons made up of a plurality of optical fiber ribbons, and a buffer layer made of silicone gel and a protective layer made of thermoplastic resin provided on the outside. A high-density optical fiber cable characterized by having a unit as a component.