JPH07218785A - Slot type optical cable - Google Patents

Abstract

PURPOSE:To obtain the slot type optical cable which secures the stability of the rim part of a slot spacer to an external force and has excellent lateral pressure characteristics, plural units, high density, and a small diameter by setting the elastic coefficient of the material of a slot spacer and the interval between adjacent storage grooves of the slot spacer in specific relation. CONSTITUTION:The optical cable which has plural ribbons 3 of optical fibers stacked and stored in plural storage grooves 2 formed axially and spirally in the outer periphery of the plastic slot spacer 1 at optional intervals in the circumferential direction satisfies the specific condition between the coefficient Ef of bending elasticity of the plastic material constituting the slot spacer 1 and the interval (t) between adjacent storage grooves 2 in the outer periphery of the slot spacer 1. Namely, Ef.t>100kg/mm. Consequently, even if the external diameter of the slot spacer 1 is decreased on condition that the size of the storage grooves 2 is made constant, the rim part of the slot spacer 1 does not deteriorate in strength and the rim part 4 becomes hard to fall down.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a slot type optical cable used for optical communication and the like.

[0002]

2. Description of the Related Art In a conventional slot type optical cable, as shown in FIG. 4, a shaft tension line A is arranged in the center and a plurality of housing grooves B are spirally formed in the outer circumference at arbitrary intervals and in the axial direction. A plurality of optical fiber tapes D are stacked and accommodated in the accommodating groove B of the formed plastic slot spacer C, the presser winding K is provided on the outer periphery of the spacer A, and the outer jacket E is coated on the outside thereof. It becomes.

The slot spacer C is formed by extruding a thermoplastic resin such as high-density polyethylene around the pit tension line A made of steel wire or FRP, and the receiving grooves B are circumferentially equidistant and axial. For example, five spirals are provided in the direction.

As the optical fiber tape D, as shown in FIG. 5, for example, eight optical fiber cores F are covered with an ultraviolet curable resin G to be integrated.

In recent years, in order to prepare for future expansion of optical communication demand, it has been required to increase the number of cores of optical cables and increase their density. Correspondingly, the number of optical fiber cores F of the optical fiber tape D used in the slot type optical cable is increasing. Therefore, the width of the optical fiber tape D becomes wider, the width of the housing groove B for housing the optical fiber tape D becomes wider, and the diameter of the slot spacer C becomes larger, so that the slot type optical cable becomes larger (larger diameter). Tend to do. However, on the other hand, there is also a demand for miniaturization (thin diameter) of the slot type optical cable.

[0006]

In order to make the slot type optical cable thinner, it is necessary to make the outer diameter of the slot spacer C as small as possible. In this case, the optical fiber tape D
If the outer diameter of the slot spacers C is reduced after the dimensions (width w, depth h in FIG. 6) of housing slots B for storing the slots are made constant, that is, the distance between the adjacent storage grooves B, that is, The width of the root portion I that supports the rim portion H (the distance between the adjacent accommodation grooves C: t in FIG. 6) must be reduced. At present, the width t of the base portion I of the slot spacer C can be reduced to about 0.7 mm in terms of molding, but the smaller the width t, the more unstable the rim portion H of the slot spacer C becomes. When an external force such as lateral pressure is applied to the mold optical cable, the rim portion H falls down and the receiving groove B
There is a problem that the optical fiber tape D housed in the optical disk tends to be damaged or damaged.

The object of the present invention is to set the stability of the rim portion of the slot spacer against external force by setting the elastic coefficient of the material of the slot spacer and the interval between the adjacent receiving grooves of the slot spacer so as to satisfy a certain relationship. Secure,
An object of the present invention is to provide a slot-type optical cable having a good lateral pressure characteristic, a large number of cores, a high density, and a small diameter.

[0008]

As shown in FIG. 1, a slot type optical cable of the present invention is formed on the outer periphery of a plastic slot spacer 1 at arbitrary intervals in the circumferential direction and in a spiral shape in the axial direction. In an optical cable in which a plurality of optical fiber ribbons 3 are stacked and accommodated in a plurality of accommodating grooves 2, the bending elastic modulus Ef of the plastic material forming the slot spacer 1 and the outer periphery of the slot spacer 1 are adjacent to each other. It is characterized in that the space t between the accommodating grooves 2 has a structure satisfying the following conditions. Ef · t> 100kg / mm

[0009]

In the slot type optical cable of the present invention, the bending elastic modulus Ef of the plastic material forming the slot spacer 1 is
Since the space t between the adjacent accommodation grooves 2 on the outer periphery of the slot spacer 1 satisfies the condition of Ef · t> 100 kg / mm, the dimension of the accommodation groove 2 is kept constant and the slot spacer 1 Even if the outer diameter is reduced, the strength of the rim portion 4 of the slot spacer 1 does not deteriorate, and the rim portion 4 is less likely to fall over even if stress such as lateral pressure is applied to the cable.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the slot type optical cable of the present invention will be described in detail with reference to FIGS. 1 in FIG.
Is a slot spacer, 2 is an accommodating groove formed in the outer periphery of the slot spacer 1 at arbitrary intervals in the circumferential direction and spirally formed in the axial direction, 3 is an optical fiber tape accommodated in the accommodating groove 2, and 5 is The shaft tension line 4 provided in the central portion of the slot spacer 1 is a rim portion provided between the adjacent accommodation grooves 2. The basic structure of these is the same as that of the slot type optical cable of FIG. 4, but in the present invention, the material of the plastic material (bending elastic modulus Ef) of the slot spacer 1 and the slot spacer 1 are The interval t between the adjacent accommodation grooves 2 on the outer circumference has a relationship of Ef · t> 100 kg / mm.

As shown in FIG. 2, the optical fiber tape 3 of FIG. 1 has a large number of single mode fiber cores (SM cores).
6 is arranged in a row of 16 cores in a row and is covered with the ultraviolet curable resin 7 all at once, and is formed in a tape shape having a width of 3 mm and a thickness of 0.25 mm.

The receiving groove 2 of the slot spacer 1 has a width of 3.5.
The slot spacer 1 has a diameter as small as 14.0 mm by reducing the distance t between the adjacent receiving grooves 2 to 0.9 mm.

By using high-density polyethylene having a flexural modulus of 120 kg / mm ² or more as the material of the slot spacer 1, it is possible to prevent the lateral pressure resistance from deteriorating as the slot spacer 1 becomes thinner. . That is, the strength of the slot spacer 1 against the force in the shearing direction (circumferential force) for tilting the rim portion 4 is the distance between the adjacent accommodation grooves 2 (width of the root portion 6 of the rim portion 4) t. And the bending elastic modulus Ef of the material of the slot spacer 1 Ef ·
Since it is proportional to the size of t, the bending elastic modulus Ef may be increased according to the reduction of the width t.

As shown in Table 1, slot spacers made of five kinds (A to E) of high-density polyethylene having different intervals t between adjacent accommodation grooves 2 and bending elastic moduli Ef were manufactured as samples.

The bottom column of Table 1 shows the measured values of the load when the rim portion 4 collapsed by applying a shearing force to the rim portion 4 under the same conditions for each sample having a length of 10 mm. Is the bending elastic modulus Ef of the material of the slot spacer 1,
It is almost proportional to the product Ef · t of the space t between the adjacent accommodation grooves 2.

Further, these slot spacers 1 have 10
FIG. 3 shows the relationship between the lateral pressure load and the amount of deformation of the slot spacer 1 when lateral pressure is applied by a 0 mm flat plate. Sample A ~
In E, when the load is 100 kg / 100 mm or less, the load and the deformation amount are almost proportional to the elastic modulus of the material of the slot spacer 1, but the samples A, B, and C each have 10
With 0, 120, 160 kg / 100 mm as the boundary
Compared with E, the amount of deformation increases sharply. This is because the rim portion 4 of the slot spacer 1 starts to fall when the lateral pressure load becomes larger than a certain value. Due to the tilting of the rim portion 4, the optical fiber tape 3 housed in the housing groove 2 of the slot spacer 1 receives an external force and causes a problem such as an increase in loss.

With respect to the slot spacer 1 in which the distance t between the adjacent accommodation grooves 2 is reduced to less than 1 mm, the minimum required value for a general optical fiber cable is 200 to 300 k.
In order to prevent loss increase in the optical fiber tape 3 even when a lateral pressure load of about g / 100 mm is applied, the product of the bending elastic modulus Ef of the material of the slot spacer 1 and the interval t between the adjacent accommodation grooves 2 is set. It is necessary to make the value of 100 kg / mm or more.

[0018]

[Table 1]

[0019]

The slot type optical cable of the present invention can satisfy a certain level of lateral pressure resistance, and can achieve multi-core, high density and small diameter.

[Brief description of drawings]

FIG. 1 is a front view showing an embodiment of a slot type optical cable of the present invention.

FIG. 2 is a front view of an optical fiber tape used in the slot type optical cable of the present invention.

FIG. 3 is an explanatory view showing a lateral pressure load and a deformation amount of the slot type optical cable of the present invention.

FIG. 4 is a front view showing an example of a conventional slot type optical cable.

FIG. 5 is a front view of an optical fiber tape used in a conventional slot type optical cable.

FIG. 6 is an explanatory diagram of a slot spacer of a conventional slot type optical cable.

[Explanation of symbols]

 1 slot spacer 2 accommodating groove 3 optical fiber ribbon

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Akihiro Otake 2-6-1, Marunouchi, Chiyoda-ku, Tokyo Furukawa Electric Co., Ltd. (72) Inventor Shigeru Tomita 1-6, Uchisaiwaicho, Chiyoda-ku, Tokyo Nippon Telegraph and Telephone Corporation

Claims (1)

[Claims] 1. An optical fiber tape core wire in a plurality of accommodating grooves (2) spirally formed in an axial direction at an outer periphery of a plastic slot spacer (1) at arbitrary intervals in the circumferential direction. In an optical cable in which a plurality of (3) are housed in a stacked manner, the bending elastic modulus Ef of the plastic material forming the slot spacer (1) and the adjacent accommodation grooves (2) on the outer circumference of the slot spacer (1) Interval t
Is a structure that satisfies the following conditions. Ef · t> 100kg / mm