JPH04245209A - High density optical fiber cable - Google Patents

Abstract

PURPOSE:To stabilize the characteristics and provide a thin dia. optical fiber cable with high density, by consolidating only those two of the optical fiber tapes laminated, which are positioned at the ends, with a protective covering layer. CONSTITUTION:A protective covering layer 5 is provided outside of a laminate of optical fiber tapes 1, and those tapes 1 situated at the ends of the laminate are protected against the side pressure, and only the two ends of the laminated tapes 1 are consolidated with the protection layer. Therefore, the side pressure due to contacting of the end tapes with the external protection layer can be relieved by the internal protection layer of each optical fiber unit even in case they gather around a tension member in the center, which should eliminate increase in the transmission loss of the optical fiber due to micro-bending.

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 an external protective layer is provided on the outside of the optical fiber tape. It is characterized in that only the optical fiber tape cores located at both ends of the fiber tape core wire are integrated with the protective coating layer.

[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.

The present invention solves this problem by providing a protective coating layer on the outside of a laminate of optical fiber tapes to protect the optical fiber tapes located at both ends of the laminate from lateral pressure, and By integrating only both ends of the laminated optical fiber tape cores with a protective layer, a high-density tape core unit is constructed that prevents deterioration of flexibility when all optical fiber tape cores are integrated. This enables higher density optical fiber cables.

In the case of the present invention, the optical fiber unit is shown in FIG.
Even when the optical fiber unit gathers around the central tension member, as in the case of FIG. There is no increase in optical fiber transmission loss.

[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 laminate of optical fiber tape cores is coated all at once, there seems to be a problem that it is difficult to remove the tape cores, but it is possible to apply a release agent such as silicone oil to the surface of the tape cores. , as shown in FIG. 2(B), the outer protective layer (22) is provided with a notch (2
3), or by 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.

This small diameter optical fiber ribbon (1) is divided into 8
The two tape cores are laminated, and dimethyl silicone with a viscosity of 50 cps is coated on both sides of the other six tape core wires, excluding the two tape core wires located at both ends. While twisted at a pitch of 500 mm, an ultraviolet curing type with a Young's modulus of 20 kg/mm2 is applied. An inner protective layer (21) made of acrylate resin and a relatively hard outer protective layer (22) were applied to form a high-density tape core unit (2) as shown in FIG. 2.

The protective coating layer of the present invention includes nylon,
Thermoplastic resins such as PBT, PVC, and polycarbonate, or resins such as silicone resin, epoxy resin, urethane resin, polyester resin, epoxy acrylate resin, urethane acrylate resin, fluorinated acrylate resin, silicone acrylate, polyester acrylate, butagerea acrylate, etc. A thermosetting type or an ultraviolet curing type can be used.

As a method of integrating only the optical fiber tape cores located at both ends with the protective coating layer, which is a feature of the present invention, it is possible to integrate only the optical fiber tape cores located at both ends with the protective coating layer. After applying a release agent such as silicone oil to both sides of the tape by means such as spray felt coating or dipping, the tape core wires are laminated, and the outer periphery of the core wires is continuously extruded and coated with thermoplastic resin, or heat or ultraviolet rays are applied. A method such as coating with a curable resin can be used.

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 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, it has a high tensile strength body (7) at the center, and a plurality of slots (6a) having a fan-shaped cross section on the outer periphery. For example, a plurality of high-density tape fiber units (2) shown in FIG. 2(b) are housed in the slots (6a) of a slot rod (6) made of plastic, respectively. A pressure tape (4) is applied on the outer periphery of the slot rod (6), and an outer coating layer (5) is further provided on the tape.

[0025]

Effects of the Invention: In making 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-forming, 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 unitize 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 ribbon, 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 Internal protective layer 22 External protective layer 23 Notch 24 Tear string 3 Tension Member 31 High tensile strength body 32 Plastic coating 4 Pressure winding 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: In an optical fiber unit in which a plurality of optical fiber tape cores constituted by a plurality of optical fiber core wires are laminated and a protective coating layer is provided on the outside, the laminated optical fiber tape core A high-density optical fiber cable comprising an optical fiber unit in which only two optical fiber tape cores located at both ends of the wire are integrated with the protective coating layer.