JPH08262292A - Coated optical fiber ribbon and optical cable formed by using the same - Google Patents

Abstract

PURPOSE: To prevent an increase in the transmission loss of optical fibers on both sides of a coated optical fiber ribbon by cabling by forming both side parts of an integral coating layer to the thickness larger than the thickness of a flat part. CONSTITUTION: The difference of the coated fiber ribbon 11 from the conventional coated fiber ribbons lies in that the thickness of the integral coating layer 12 of both side parts 11a, 11a thereof is larger than the thickness of flat parts 11b, 11b. In such a case, the thickness of the integral coating layer 12 of both side parts 11a, 11a is expressed by a width; Wa and the thickness of the integral coating layer 12 of the flat parts 11b, 11b is expressed by a width; Wb. The width Wb is preferably formed to <=40μm in order to increase the number of the coated fiber ribbons 4 which can be housed into a housing body, such as slot rod. Further, the width Wa is set preferably in a range of 40 to 250μm. The coated fiber ribbons 11 are housed in the slot grooves of the slot rod in the state of superposing plural sheets on each other and the circumference thereof is provided with tape winding layers and is clad with a sheath, by which the optical cable is formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical fiber tape core wire suitable for being housed in a housing such as a slot rod to form an optical cable, and an optical cable using the same.

[0002]

2. Description of the Related Art At present, subscriber optical cables having a capacity of more than 1000 fibers have been developed. As such an optical cable, a structure having a structure as shown in FIG. 2 has been proposed. This optical cable 1 is of a so-called slot type, and an optical fiber tape core wire (hereinafter abbreviated as tape core wire) 4 is provided in a plurality of spiral slot grooves 3 formed on an outer peripheral surface of a slot rod 2. It is housed in a state where multiple sheets are stacked. The slot rod 2 is a long body made of plastic such as polyethylene, and a tension member 5 made of a twisted metal wire or a fiber reinforced plastic (FRP) rod is provided at the center thereof. A tape winding layer 6 formed by winding a tape such as a polyester tape is provided on the circumference of the slot rod 2, and a sheath 7 made of polyvinyl chloride or the like is coated on the tape winding layer 6.

As shown in FIG. 4, the tape core wire 4 is formed by arranging a plurality of optical fiber wires 8 in parallel and coating them with a collective coating layer 9 made of an ultraviolet curable resin or the like.
Usually, the optical fiber element wire 8 having an outer diameter of 250 μm is used. By the way, when the optical cable as shown in FIG. 2 is constructed, the tape core wire 4 which can be accommodated in the slot rod 2
In order to make the number of lines extremely large, a thin-walled tape core wire in which the thickness of the collective covering layer 9 of the tape core wire 4 is thinned is being studied.
For example, the thickness of the collective coating layer in a normal tape core wire is formed to about 75 μm, whereas the thinnest portion of both side portions 4a, 4a and flat portions 4b, 4b of the tape core wire 4 is 40 μm or less. The thin tape core wire that has been made is being considered.

[0004]

However, such a thin tape core wire has a drawback that the loss characteristic against lateral pressure is inferior because the collective coating layer 9 as a protective layer is thin.
Therefore, when the tape core wire 4 is accommodated in the slot groove 3 of the slot rod 2 to form a cable, the slot groove 3
When one end of the tape core wire 4 hits one of the side walls of the optical fiber, the optical fiber element wire 8 may be subjected to lateral pressure, resulting in an increase in transmission loss. This increase in transmission loss is caused by the fact that, among the optical fiber wires 8 forming the tape core wire 4, the optical fiber wires 8a, 8a located at both ends near the side wall of the slot groove 3 are directly subjected to a large lateral pressure. Therefore, the optical fiber wires 8a, 8a at both ends are
It became a big problem and became a problem.

Therefore, an object of the present invention is to increase the transmission loss of the optical fiber wires located at both ends of the tape core wire when the tape core wire is housed in a housing such as a slot rod to form an optical cable. To prevent this.

[0006]

This problem is solved by making the thickness of both side portions of the collective coating layer of the tape core wire equal to or larger than the thickness of the flat portion. The thickness of both sides of the collective coating layer is preferably in the range of 40 to 250 μm.

The present invention will be described in detail below with reference to the drawings. FIG. 1 shows an example of the tape core wire 11 of the present invention. The tape core wire 11 of this example is different from the conventional tape core wire 4 shown in FIG.
The thickness of the collective coating layer 12 of 11a is equal to that of the flat portions 11b, 1
It is thicker than 1b. This side part 11
The thickness of the collective coating layer 12 of a and 11a is shown by the width; Wa in FIG. 1, and the thickness of the collective coating layer 12 of the flat portions 11b, 11b is shown by the width; Wb in FIG. In the present invention, Wb is 40 because it increases the number of tape core wires 4 that can be accommodated in the accommodation body such as the slot rod 2.
It is preferably formed with a thickness of less than μm. And Wa is preferably in the range of 40 to 250 μm. If Wa is less than 40 μm, the effect of preventing an increase in transmission loss cannot be obtained.
If it exceeds 0 μm, both side portions 11a, 1 of the collective coating layer 12
1a tends to swell, which is not preferable in manufacturing.

In order to manufacture such a tape core wire 11, it is possible to slightly change the shape of the discharge port of the die for forming the collective coating layer 12. Further, the collective coating layer 12 is preferably formed of an ultraviolet curable resin, but other resins such as a polyamide resin and a silicone resin can be used. However, a material that is too hard is not preferable in terms of the effect of relaxing lateral pressure, and it is desirable to use a resin having an elastic modulus in the range of 50 to 150 kg / mm ² .

The optical cable of the present invention, for example, as shown in FIG. 2, accommodates a plurality of the above-mentioned tape core wires 11 in the slot groove 3 of the slot rod 2 in a state of being superposed.
A tape winding layer 6 is provided on the circumference and a sheath 7 is covered. The slot groove 3 is preferably formed, for example, to have an inner width of about 2.8 mm and a depth of about 4 mm, and preferably 10 tape core wires 11 are accommodated in a stacked state. Further, in the present invention, the housing used for forming the cable is not limited to the slot rod 2, and any suitable one can be used as long as it has a structure capable of housing a large number of tape core wires 11.

Another example of the container is shown in FIG.
A gutter-shaped container having a structure as shown in (a) may be used.
Reference numeral 21 in FIG. 3A is a tension member made of a twisted metal wire, an FRP rod, or the like. A plurality of trough-shaped containers 22 are twisted around the tension member 21, and a tape winding layer 23 formed by winding a tape such as polyester tape is provided on the plurality of trough-shaped containers 22. The individual trough-shaped containers 22 are twisted together, a tape winding layer 23 is provided, and a sheath 24 made of polyvinyl chloride or the like is coated on the tape winding layer 23. The trough-shaped container 2
2 has a U-shaped cross section as shown in FIG. 3 (b), for example, an elongated body made of a plastic such as polyethylene, preferably having an inner width of about 2.8 mm and a depth of about 4 mm. Is. The inside of the trough-shaped container 22 is shown in FIG.
As shown in (b), a plurality of optical fiber ribbons 11 ... Are accommodated in a stacked state. The optical cable has a structure in which a plurality of trough-shaped containers 22 are twisted together as shown in FIG. 3A, and a plurality of tape core wires 11 are stacked and accommodated in the trough-shaped container 22. It is also possible to bundle a plurality of the shape-containing bodies 22 and collect them, provide a tape winding layer, and form a sheath.

In the tape core wire 11 of the present invention, since both side portions 11a, 11a are thickly coated, the tape core wire 11 hits the slot groove 3 or the side wall of the trough-shaped container 22 to cause lateral pressure. Even if it is received, the lateral pressure is not transmitted to the internal optical fiber wires 8 and the transmission loss of the optical fiber wires 8a, 8a located on both sides does not increase. Hereinafter, examples will be shown to clarify the action and effect.

[0012]

EXAMPLE A bare single mode optical fiber having an outer diameter of 125 μm was coated with an ultraviolet curable resin to obtain an optical fiber element wire having an outer diameter of 250 μm. Eight optical fiber strands were arranged in parallel and passed through a die to form a collective coating layer made of an ultraviolet curable resin to obtain an 8-fiber ribbon. At this time, the shape of the discharge port of the die is changed to reduce the coating thickness on both sides to 2
It was changed in the range of 0 to 300 μm. The coating thickness of the flat portion was 20 μm or 40 μm. The tape core wire thus obtained is made of polyethylene and has an outer diameter of 24
mm slot rod slot groove (internal width 2.8 mm,
10 sheets were piled up in a depth of 4 mm) to form a cable.
The change in transmission loss of each tape core wire before and after forming a cable was measured at a wavelength of 1.55 μm. As a result of the measurement of each of the 10 stacked cores of the tape, the maximum value of the transmission loss increase is shown in Table 1 below.

[0013]

[Table 1]

As is clear from the results shown in Table 1, in the case of the tape core wires (Nos. 1 and 2) whose coating thickness on both sides is 30 μm or less, the transmission loss greatly increases due to the cable formation. . On the other hand, it was confirmed that an increase in transmission loss due to cable formation can be suppressed by setting the thickness of both side portions to 40 μm or more (No. 3 to 9) while the thickness of the flat portion is 40 μm or less. In addition, the tape core wire (No. 7) having a thickness of 300 μm on both sides is
Both sides of the collective coating layer were swollen, which made manufacturing difficult.
Therefore, it was confirmed that the thickness of both side portions is appropriately 250 μm or less.

[0015]

As described above, the optical fiber tape core wire of the present invention is an optical fiber tape core wire in which a plurality of optical fiber element wires having an outer diameter of 250 μm are arranged and integrated by a collective cover layer. The thickness of both side portions is equal to or greater than the thickness of the flat portion. Further, the optical cable of the present invention comprises a plurality of the above-mentioned optical fiber ribbons which are stacked and housed in a housing. Therefore, according to the present invention, it is possible to prevent an increase in transmission loss of the optical fiber element wires located on both sides of the optical fiber tape core wire due to the cable formation. Therefore, it is possible to achieve high density in the optical cable without deteriorating the transmission loss characteristic of the optical fiber strand.

[Brief description of drawings]

FIG. 1 is a sectional view showing an example of an optical fiber ribbon according to the present invention.

FIG. 2 is a schematic sectional view showing an embodiment of the optical cable of the present invention.

3A and 3B show another embodiment of the optical cable of the present invention, wherein FIG. 3A is a schematic sectional view of the optical cable, and FIG. 3B is a sectional view showing a trough-shaped container and an optical fiber tape core wire accommodated in the container. Is.

FIG. 4 is a cross-sectional view showing a conventional optical fiber ribbon.

[Explanation of Codes] 2 ... Slot rod, 8 ... Optical fiber element wire, 11 ... Optical fiber tape core wire, 11a ... Both side portions, 11b ... Flat portion, 12 ... Collective coating layer, 22 ... Trough-shaped container.

Claims (3)

[Claims] 1. In an optical fiber tape core wire in which a plurality of optical fiber element wires having an outer diameter of 250 μm are lined up and integrated by a collective coating layer, the thickness of both sides of the collective coating layer is equal to or greater than the thickness of a flat portion. An optical fiber tape core wire characterized by. 2. The thickness of both sides is 40 to 250 μm.
The optical fiber ribbon according to claim 1, wherein 3. An optical cable comprising a plurality of optical fiber ribbons according to claim 1 or 2 which are stacked and housed in a housing.