JPH08129122A - Optical fiber ribbon - Google Patents

Abstract

PURPOSE: To provide an optical fiber ribbon which has an excellent side pressure resistant characteristic and retains the initial reliability without impairment in spite of an increase in its density. CONSTITUTION: This optical fiber ribbon 6 is formed by arranging plural pieces of optical fibers 4a to 4h successively coated and formed with fiber soft layers 2a to 2h and fiber hard lagers 3a to 3h of UV curing resins varying in Young's modulus in parallel on the outer peripheries of optical fibers 1a to 1h and coating the outer peripheries of these optical fibers 4a to 4h with UV curing resins to form a ribbon-shaped body. The optical fiber ribbon described above is formed by approximately equalizing the thickness t1 of the fiber soft layers 2a to 2h of the optical fibers 3a to 3h and the total thickness of the thickness t2 of the fiber hard layers 3a to 3h and the thickness t3 of the tape coating layers 5.

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, and more particularly to an optical fiber tape for high density mounting.

[0002]

2. Description of the Related Art In general, an optical fiber tape has a single-mode fiber having a fiber diameter of 125 μm or a multi-mode fiber with two kinds of coating layers, a soft wire layer and a hard wire layer, formed on the outer periphery thereof to have an outer diameter of 250 μm. This is a tape formed by coating the outer periphery of a plurality of selected optical fiber strands arranged in parallel and coating the outer periphery.

The material of the coating layer is UV (ultraviolet) because it can be coated with a die and can be cured in a short time.
A curable urethane acrylate resin is often used.

[0004]

SUMMARY OF THE INVENTION By the way, in order to spread the subscriber line network of optical fibers, it is desired to be 3000-4000.
The demand for high-density optical fiber cables is increasing. In order to realize this, it is necessary to increase the number of cores and the diameter of the optical fiber tape. However, this will impair the reliability of the optical fiber cable.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above problems and to provide an optical fiber tape which is excellent in lateral pressure resistance and does not impair reliability even if the density is increased.

[0006]

In order to achieve the above object, the present invention provides an optical fiber in which a soft wire layer and a hard wire layer are successively coated on the outer circumference of an optical fiber with an ultraviolet curable resin having a different Young's modulus. A plurality of strands are arranged in parallel, and in the optical fiber tape formed into a tape-shaped body by coating the outer periphery of these optical fiber strands with an ultraviolet curable resin, the thickness t1 of the soft layer of the optical fiber strands And the thickness of the wire hard layer
The total thickness t2 and the thickness t3 of the tape coating layer are substantially the same as each other.

In addition to the above structure, the present invention sets the Young's modulus of the wire soft layer to 0.1 to 10 MPa, and the Young's modulus of the wire hard layer and the tape coating layer to 1500 to 2000 MPa.

[0008]

[Operation] When the thickness of the soft wire layer is increased and the Young's modulus is decreased, the cushioning effect is increased. When the hard wire layer and the tape coating layer are increased and the Young's modulus is increased, the tape rigidity is increased. . When the tape structure is limited to some extent, the thickness of the wire soft layer, the wire hard layer, and the tape coating layer has a maximum value or an appropriate range of lateral pressure resistance.

Then, the thickness t1 of the soft wire layer of the optical fiber wire, the thickness t2 of the hard wire layer of the optical fiber, and the thickness of the tape coating layer.
When the total thickness of t3 is set to be substantially the same, it is possible to realize an optical fiber tape having excellent lateral pressure resistance and capable of achieving high density.

[0010]

An embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 is a transverse sectional view of an embodiment of the optical fiber tape of the present invention, and FIG. 2 is an enlarged view thereof.

Example 1 A soft wire layer (Young's modulus, about 1 MPa) 2a having a thickness t1 (20 μm) is formed on the outer circumference of a single mode fiber 1a having an outer diameter of about 125 μm by a UV curable urethane acrylate resin. Thickness t2 (10μ
m) wire hard layer (Young's modulus, about 1700 MPa) 3
and a are sequentially coated to form the optical fiber element wire 4a. Eight optical fiber strands 4a to 4h formed in the same manner are arranged in parallel, and on the outer circumferences of these optical fiber strands 4a to 4h,
Tape coating layer with a thickness of t3 (10 μm) (Young's modulus, about 17
00 MPa) 5 and the final coating layer thickness t4 (205
μm) 8-fiber optical fiber tape 6 was manufactured.

The eight-core optical fiber tape 6 has an outer diameter of about 50.
Side pressure resistance by measuring the amount of loss increase in light of wavelength λ = 1.55 μm when one layer of 300 m long is wound around a smooth aluminum bobbin (not shown) with a surface of 0 mm and wound one layer. Was evaluated. At this time, the tension per core of the optical fiber strands 4a to 4h in the optical fiber tape 6 was 3.75 N and T / R = 1.5 g / mm.

Next, the operation of the embodiment will be described.

Generally, in a small-diameter optical fiber tape, a difference in structure between the optical fiber element wire and the tape coating layer greatly affects the lateral pressure resistance. Increasing the thickness of the wire soft layer and decreasing the Young's modulus enhances the cushioning effect, and increasing the thickness of the wire hard layer and the tape coating layer and increasing the Young's modulus increases the tape rigidity.

The Young's modulus of the ultraviolet-curable urethane acrylate for improving the lateral pressure resistance is 0.
It is 1 to 2000 MPa.

Therefore, the wire soft layers 2a to 2h have a low Young's modulus (0.1 to 10 MPa) and the wire hard layers 3a to 2h.
A resin having a high Young's modulus (1500 to 2000 MPa) is selected for 3 h. Moreover, in order to realize a high-density optical fiber cable of 3000 to 4000 fibers, a thickness of 200 to 300 is required.
An optical fiber tape of about μm is required. When the structure of the optical fiber tape is limited to some extent,
The thickness t1 of the soft wire layers 2a to 2h, the hard wire layers 3a to 3h
The thickness t2 of 3h and the thickness t3 of the tape coating layer 5 have a maximum value or an appropriate range of lateral pressure resistance characteristics, respectively.

That is, the thickness t1 of the soft wire layers 2a to 2h of the optical fiber wires 4a to 4h and the hard wire layers 3a to 3h.
The relationship between the thickness t2 of the tape and the thickness t3 of the tape coating layer 5 is expressed by the equation 1

[0019]

## EQU00001 ## Thickness t1 of the soft wire layers 2a to 2h: (thickness t2 of the hard wire layers 3a to 3h + thickness t3 of the tape coating layer 5) =
By setting the ratio to satisfy 1: 1, a large tape rigidity and a high cushioning effect can be obtained, and an optical fiber tape which is excellent in lateral pressure resistance characteristics and can be densified can be realized. However, since there are temperature changes during fiber drawing and tape formation, and variations in coating material between lots, it is necessary to consider the width t1 of the soft wire layer of about ± 10%.

(Examples 2 and 3 and Comparative Examples 1 to 6) The materials of the optical fiber element wire and the tape coating layer have the same structure as in Example 1, and the thickness t1 of the element wire soft layer and the element wire. An eight-fiber optical fiber tape was manufactured in which only the hard layer thickness t2, the tape coating layer thickness t3, and the final coating layer thickness t4 were changed. The respective dimensions are shown in Table 1, and the lateral pressure resistance characteristic evaluation results are shown in FIG. In Fig. 3, the horizontal axis is the thickness of the soft wire layer.
It shows t1, and the vertical axis shows the amount of loss increase.

[0021]

[Table 1]

From FIG. 3 and Table 1, when the thickness t4 of the final coating layer of the optical fiber tape is the same, in the optical fiber tape structure, the optical fiber tape satisfying the equation (1) has the best value for lateral pressure resistance. showed that.

Here, the optimum conditions of the optical fiber tape will be described.

In Example 1 and Comparative Examples 1 and 2, Example 2 and Comparative Examples 3 and 4, and Example 3 and Comparative Examples 5 and 6, the final coating layer thickness was set.
t4 is the same optical fiber tape, the thickness of the strand soft layer
Only the ratios of t1, the thickness t2 of the wire hard layer and the thickness t3 of the tape coating layer are changed. Comparing these, it can be seen that the optical fiber tape of the example in which the coating structure satisfies the formula 1 has the best lateral pressure resistance.

This is because when the soft wire layer is thicker, the stress from the outside is more likely to be relieved, but the hard wire layer and the tape coating layer are thinned, so that the rigidity of the entire optical fiber tape is lowered and bending is difficult. This is because it becomes weaker.

As described above, according to this embodiment, a material having a low Young's modulus is used for the soft wire layer, a material having a high Young's modulus is used for the wire hard layer and the tape coating layer, and the optical fiber wire is used. Since the thickness t1 of the wire soft layer, the thickness t2 of the wire hard layer and the total thickness t3 of the tape coating layer are made substantially the same, the lateral softness is excellent. It is possible to realize an optical fiber tape that can be highly densified.

In this embodiment, the coloring layer is not provided on the outer circumference of the wire hard layer, but the invention is not limited to this. A coloring layer may be provided, but in consideration of the thinning, the wire may be provided. It is more efficient to color the hard layer. Further, although the case where the number of optical fiber strands is 8 has been described in the present embodiment, the present invention is not limited to this. Further, in this embodiment, the Young's modulus of the wire soft layer is about 1 MPa, and the Young's modulus of the wire hard layer and the tape coating layer is about 1700 MPa. However, the Young's modulus of the wire soft layer is not limited to this. 0.1-
The Young's modulus of the wire hard layer and the tape coating layer may be set to 10 MPa to 1500 MPa to 2000 MPa.

[0028]

In summary, according to the present invention, the following excellent effects are exhibited.

A material having a low Young's modulus is used for the soft wire layer, and a material having a high Young's modulus is used for the hard wire layer and the tape coating layer to optimize the tape structure, thereby providing excellent lateral pressure resistance and high lateral pressure resistance. It is possible to realize an optical fiber tape that can be densified.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of an embodiment of the optical fiber tape of the present invention.

FIG. 2 is an enlarged view of FIG.

FIG. 3 is a diagram showing a lateral pressure resistance characteristic evaluation result.

[Explanation of Codes] 1a to 1h Optical fiber 2a to 2h Elementary wire soft layer 3a to 3h Elementary wire hard layer 4a to 4h Optical fiber elemental wire 5 Tape coating layer 6 Optical fiber tape

Claims (2)

[Claims] 1. A plurality of optical fiber wires in which a soft wire layer and a hard wire layer are sequentially coated with an ultraviolet curable resin having different Young's moduli on the outer circumference of the optical fiber are arranged in parallel, and these optical fibers are formed. In an optical fiber tape in which a tape-shaped body is formed by coating the outer circumference of a strand with an ultraviolet curable resin, the strand soft layer thickness t1 of the optical fiber strand, the strand hard layer thickness t2, and the tape coating layer. The optical fiber tape is characterized in that it is formed so that the total thickness t3 thereof is substantially the same. 2. The Young's modulus of the soft wire layer is 0.1 to 10.
The optical fiber tape according to claim 1, wherein the Young's modulus of the hard wire layer and the tape coating layer is 10 MPa to 2000 MPa.