KR20000046917A - High strength optical fiber cable - Google Patents

Abstract

PURPOSE: A high strength optical cable is provided to have an improved tensile strength together with reducing an outer diameter of the optical cable. CONSTITUTION: A high strength optical cable includes cores having a plurality of optical units(12) comprised of respective optical fibers. At the center of the cores is arranged a central reinforcing member(11) which extends in a longitudinal direction of the optical cable. The plurality of optical units(12) wrap around the central reinforcing member(11). The optical units(12) may be formed to be extended in parallel with respect to a longitudinal direction of the optical cable or to be stranded as a vibrating waveform. The plurality of the optical units(12) are made in the form of tubes having a plurality of the optical fibers. The fiber disposed within the tube is formed to be a helical type, and thus the length of the tube is set to be shorter than that of the optical fiber such that the conical fiber. A plastic jacket(15) is disposed around the cores of the present invention. A plurality of external reinforcing members(13) are disposed between the jacket(15) and the core. The external members(13) are symmetrically disposed without stranding. The external members(13) are made of steel wires or rod-shaped fiberglass reinforced resin having high elastic modulus like the central reinforcing member(11).

Description

High strength fiber optic cable

The present invention relates to an optical fiber cable. In particular, the present invention relates to a high-strength optical fiber cable which further improves tensile strength by disposing reinforcing members in the center of the core layer and the outside of the core layer of the optical cable.

Advances in fiber optic communications have been rapid. However, the direction of technological progress is still changing. In one example, previous fiber systems were designed to operate at wavelengths of about 0.8 μm, while current fiber systems are designed to operate at wavelengths of about 1.3 μm. Now, there is a growing interest in systems having an operating wavelength of about 1.55 μm in order to benefit from the loss window present in the silicon base optical fiber in the vicinity of 1.55 μm. Another example of the transition is the trend from multimode fibers to single mode fibers due to the demand for greater bandwidth.

Although it is desirable to have a large bandwidth and a small size, the optical fiber for optical transmission is physically brittle, exhibits low strain breakage characteristics under tensile load, and degrades optical transmission characteristics upon refraction.

The degradation of transmission characteristics due to refraction is known as microbending loss. As a result, cable structures have evolved to physically protect optical fibers.

Cables for use in conduits shall be able to withstand the tensile loads and stresses caused by deflection when the cables are pulled. Cable structures developed for fiber optics include loose tube cables and twisted and ribbon cables.

Examples of loose tube cables are described in D. Lawrence and P. Bark's "Current Stage of Mini-Unit Cables" on pages 301 to 307 of the 32nd International Wire and Cable Symposium, 1983. 4,153,332.

Ribbon cables include one or more ribbons each comprising a plurality of optical fibers arranged in a planar array. U.S. Patent No. 4,078,853 describes a cable comprising a core of multiple ribbons surrounded by a loosely fitted plastic inner tubular jacket. The plastic outer jacket is reinforced by a reinforcing member that is firmly coupled to the outer jacket.

In some cases, ie, greater tensile loads are foreseen in a conduit system that includes many deflections, such as in a loop plant in downtown. Suitable and improved optical communication cables for such applications are described in US Pat. No. 4,241,979.

A bedding layer in which the reinforcing member is spirally wound is added between the inner jacket and the outer jacket extruded from plastic to adjust the extent to which the reinforcing member is embedded by the outer jacket. The cable includes two separate reinforcing member layers wound in opposite spirals. Under constant tensile load these two stiffener layers produce equal but opposite torque for the cable and are free of twisting.

Ribbon cables have many excellent properties. One of them is that the connection of the array is relatively easy. The array connector described in US Pat. No. 3,864,018 enables factory mounting and significantly saves the time required in a single fiber joint method. Another advantage is that the occupancy density per unit area of the cable can be higher than for stranded cables.

In another type of optical communication cable, a plurality of optical fibers are embedded in an injected plastic tube to form a unit, and a plurality of such tube units are embedded in a common injected plastic tube surrounded by an outer sheath system.

In general, the optical fiber embedded in each tube unit is twisted around the central reinforcing member. Center reinforcement members are often used because they are relatively easy to assemble into the cable. In addition, the cable is more easily deflected when the reinforcing member is a central reinforcing member than when it is integral with the jacket system. However, when such a cable is deflected, the central reinforcement member will in some cases press one or more optical fibers against the tube and cause damage.

1 to 2D show the structure of a conventional optical fiber cable.

1 shows an optical fiber cable with a reinforcing member disposed in the center of the cable. That is, the central reinforcing member 1 is disposed in the longitudinal direction of the cable, and a plurality of optical fibers or a plurality of optical units 3 are disposed around the reinforcing member 1. An outer jacket 5 is disposed around the plurality of optical fibers or optical units. At this time, the optical fiber or optical unit 3 may not be intentionally twisted or may be wound to surround the reinforcing member. Each of the plurality of optical units 3 contains a plurality of optical fibers.

2a to 2d show a conventional example in which the reinforcing member 1 is arranged in the outer sheath system of the cable. That is, one or more reinforcing members 1 are disposed between the cores 3, 4 of the cable and the outer jacket 5, and a plurality of optical fibers 3 are included inside the inner jacket 4.

2A shows an example in which two reinforcing members 1 are symmetrically disposed between the inner jacket 4 and the outer jacket 5. FIG. 2B shows an example in which two sets of reinforcing members 1 in a pair are arranged symmetrically between the inner jacket 4 and the outer jacket 5. 2C shows an example in which a plurality of reinforcing members 1 are symmetrically disposed between the inner jacket 4 and the outer jacket 5. 2D shows an example in which the reinforcing member 1 is wound horizontally on the outer circumferential surface of the inner jacket 4.

As described above, in the related art, a configuration is known in which a reinforcing member is disposed at the center of the core or a plurality of reinforcing members are disposed in the shell system. However, in such an optical communication cable, the outer diameter of the reinforcing member disposed in the cable must be largely designed in order to secure sufficient tensile strength, and this increases the overall weight of the cable, thereby causing problems such as difficulty in cable wiring work.

Therefore, a cable for optical fiber transmission different from the conventional one is required.

The problem of the aforementioned optical communication cable is overcome by the cable according to the present invention. Accordingly, it is an object of the present invention to provide a high-strength optical fiber cable that can secure sufficient tensile strength while reducing the outer diameter and weight of the cable.

The optical fiber cable of the present invention is located in the center of the optical fiber cable, the first reinforcing member of a high modulus of elasticity extending in the longitudinal direction, the optical wave core is configured so that a plurality of optical units having a plurality of optical fibers surround the first reinforcing member Wow; A jacket made of a plastic material and surrounding the optical wave core; And a second reinforcement member of a plurality of high modulus modulus materials positioned between the optical wave core and the jacket and parallel to the cable longitudinal axis and in a straight line with the first reinforcement member. The first and second reinforcing members cooperate with each other to provide the cable with a predetermined tensile stiffness.

The plurality of optical units is a tube including a plurality of optical fibers, the length of the tube is set slightly shorter than the optical fiber so that the optical fiber disposed in the tube is spiral, the inside of each of the plurality of optical units is filled with a soft gel.

Further, each of the plurality of second reinforcing members is arranged symmetrically to each other without being intentionally twisted, and each of the plurality of optical units is a plurality of optical fiber bundles which are bound to each other without being intentionally twisted.

In addition, in the present invention, a plurality of optical units may be in close contact with the first reinforcing member and intentionally wound in a predetermined direction.

In addition, the present invention may additionally include an outer jacket layer or a reinforcing outer layer of a metal material on the outside of the jacket.

The first and second reinforcing members are rod-shaped metal or non-metallic.

Another aspect of the optical fiber cable of the present invention is a first reinforcing member of a high modulus modulus material, which is located in the center of the optical fiber cable and extends in the longitudinal direction, a slot spacer surrounding the first reinforcing member, and a plurality of grooves present in the groove of the slot spacer. A core composed of a ribbon optical fiber; A jacket made of a plastic material and surrounding the core; And a second reinforcement member of a plurality of high modulus modulus materials positioned between the core and the jacket and parallel to the first reinforcement member and parallel to the first reinforcement member.

Other objects and advantages of the invention will be described below and will be appreciated by the practice of the invention. Furthermore, the objects and advantages of the invention can be realized in particular by the means and combinations indicated in the appended claims.

The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate presently preferred embodiments of the invention and, together with the foregoing general description and the detailed description of the following preferred embodiments, serve to explain the principles of the invention. .

Figure 1 shows the structure of a conventional optical fiber cable with a reinforcing member disposed in the center of the core.

2A to 2D show the structure of a conventional optical fiber cable in which a reinforcing member is disposed outside the core.

Figure 3 shows the structure of a high-strength optical fiber cable of the buffer core type according to the present invention.

Figure 4 shows the structure of a high-strength optical fiber cable for processing according to the present invention.

Figure 5 illustrates the structure of a slotted core type high strength optical fiber cable according to the present invention.

<Explanation of symbols for the main parts of the drawings>

11: center reinforcement member 13: external reinforcement member

12: optical unit 14: ribbon optical fiber

15: jacket 17: support line

19: slot spacer

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

It should be noted that in the following description, only parts necessary for understanding the operation according to the present invention will be described, and descriptions of other parts will be omitted so as not to obscure the subject matter of the present invention.

3 to 5 show a preferred embodiment of the cable of the invention.

3 and 4, the cable comprises a core having a plurality of optical units 12 composed of a plurality of individual optical fibers. In addition, a central reinforcing member 11 extending in the longitudinal axis direction of the cable is disposed at the center of the core. The plurality of optical units 12 surround the center reinforcement member 11. Each optical unit 12 is twisted or not twisted. That is, the optical unit 12 extends in parallel with the longitudinal axis of the cable or is formed in a vibration waveform.

It will be appreciated that the optical fibers included in each optical unit 12 of the preferred embodiment are assembled without being twisted together and that the optical unit 12 itself is assembled to an infinite length. The optical fiber may be bent in a wave shape along the optical unit part so that each optical fiber has a length slightly longer than the skin system. In addition, the plurality of optical units 12 is a tube including a plurality of optical fibers, the length of the tube is set slightly shorter than the optical fiber so that the optical fiber disposed inside the tube is spiral. This prevents excessive strain on the optical fiber during manufacture or during installation and cable repair.

Each of the plurality of optical units 12 may be filled with a soft gel.

In addition, each of the plurality of optical units 12 may be a plurality of optical fiber bundles intentionally bound together without being twisted.

The central reinforcing member 11 uses a steel wire or rod-like glass reinforced resin (FRP) material having a high modulus of elasticity.

The optical unit 12 is a loose tube structure in which at least one or more than 24 optical fibers are loosely inserted into a protective tube made of plastic together with a jelly-like filling material.

The core has a structure in which a plurality of optical units 12 are wound on the central reinforcing member 11, and each gap is filled with a jelly-like compound to prevent immersion in the cable length direction.

The plurality of optical units 12 have a structure of being wound in one direction by being in close contact with the central reinforcing member 11 or having a structure of winding in both directions in which the winding direction is reversed at regular intervals.

The plastic jacket 15 is disposed around the core of the present invention. A plurality of external reinforcing members 13 are disposed between the jacket 15 and the core.

Each of the plurality of external reinforcing members 13 is intentionally arranged symmetrically without being twisted. The external reinforcing member 13, like the central reinforcing member 11 has a steel wire or rod-like glass reinforced resin material having a high modulus of elasticity.

In addition, the jacket 15 is made of polyethylene, polyurethane, fluoro polymer, polyvinyl chloride, or tefgel. The jacket 15 protects the optical fiber from dust, moisture, sunlight, abrasion, grinding, and temperature change.

3 illustrates a configuration in which two external reinforcing members 15 are symmetrically disposed.

4 shows a configuration in which two external reinforcing members 15 are arranged symmetrically on both sides of a concentric circle, and a support line 17 for suspending the optical cable in the air is provided outside the cable.

In the case of the optical fiber cable of FIGS. 3 and 4, an outer jacket layer or a reinforcing outer layer of metal may be additionally included outside the jacket 15.

5 shows a slotted core optical cable.

As shown in FIG. 5, in the slotted core optical cable, a central reinforcing member 11 having the same shape as that shown in FIGS. 3 and 4 is disposed at the center of the cable, and around the central reinforcing member 11. Slot spacers 19 are disposed. In the groove of the slot spacer 19, a plurality of ribbon optical fibers 14 are present.

Therefore, in the optical cable of FIG. 5, the core reinforcing member 11, the slot spacer 19, and the plurality of optical fibers 14 form a core. The outer reinforcing member 13 and the jacket 15 arranged around the core are the same as in Figs.

Hereinafter, the embodiment of the present invention and the conventional example will be compared with each other through the specifications and characteristics of the cable.

As a conventional example, an optical fiber cable having the configuration of FIG. 1 is manufactured and referred to as Comparative Example 1. FIG. As an embodiment of the present invention, a high-strength optical fiber cable having the configuration of FIG. 3 is manufactured and referred to as Example 1. FIG.

The specifications and characteristics of the prepared Comparative Example 1 and Example 1 are shown in Table 1 below.

Comparative Example 1 Example 1 Cable weight (kg / km) 120 80 Cable outer diameter (mmΦ) 10 7 Loose Tube Outer Diameter (mmΦ) 2 One Reinforcing member outer diameter (mmΦ) 2 One Cable modulus (km) 1.5 2

* Cable elastic modulus = cable tensile strength (kg) / cable unit weight (kg / km)

As can be seen from Table 1, in Example 1, instead of one of the 2mm Φ thickness of Comparative Example 1, by placing the three 1mm thickness symmetrically on the cable center and jacket, the cable outer diameter and weight is reduced to 30% .

Actual mechanical strength required in the installation and operation of the optical cable is determined by the cable elastic modulus. The cable elastic modulus of Example 1 is increased by 30% compared with the conventional Comparative Example 1.

In addition, in Example 1, the weight and outer diameter of the cable are reduced by 30% or more, and the cross-sectional area of the reinforcing member is reduced by 25% compared with Comparative Example 1.

Therefore, the high-strength optical fiber cable of the present invention is an economical and excellent optical fiber cable.

Additional advantages and modifications will be readily apparent to those skilled in the art. Thus, in a broad aspect, the invention is not limited to the specific details and representative apparatus shown and described herein.

Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents.

As described above, the optical fiber cable of the present invention can reduce the outer diameter of the cable, and it is economical because the manufacturing cost of the cable is low.

In addition, the optical fiber cable of the present invention can be laid easily and less risk of cable damage because the external reinforcing member has a function of the internal tensile function even when the cable is applied to the external jacket during the cable installation.

The optical fiber cable of the present invention can increase the flexural modulus of the cable can reduce the risk of damage to the optical fiber when handling.

In the optical fiber cable of the present invention, the central reinforcing member and the external reinforcing member are arranged in parallel with the central axis in the longitudinal direction of the cable to disperse the tensile force in the process of laying and operating the cable, thereby preventing damage of the optical fiber and the cable jacket from excessive tensile strength. Damage can be prevented.

Claims (11)

In optical fiber cable, An optical wave core positioned in the center of the optical fiber cable, the first reinforcing member having a high modulus of elasticity extending in a longitudinal direction, and a plurality of optical units including a plurality of optical fibers surrounding the first reinforcing member; A jacket made of a plastic material and surrounding the optical wave core; A second reinforcement member of a plurality of high modulus modulus materials positioned between the optical wave core and the jacket and parallel with the first reinforcement member and parallel to the cable longitudinal axis; And the first and second reinforcing members cooperate with each other to provide the cable with a predetermined tensile stiffness. The method of claim 1, The plurality of optical units is a tube including a plurality of optical fibers, the optical fiber cable, characterized in that the length of the tube is set slightly shorter than the optical fiber so that the optical fiber disposed in the tube is spiral. The method of claim 2, Optical fiber cable, characterized in that the inside of the optical unit is filled with a soft gel. The method of claim 1, And each of the plurality of second reinforcing members is disposed symmetrically to each other without being intentionally twisted. The method of claim 1, And each of the plurality of optical units is a plurality of optical fiber bundles intentionally bound together without being twisted. The method of claim 1, And the plurality of optical units are in close contact with a circumference of the first reinforcing member and intentionally wound in a predetermined direction. The method of claim 1, And an outer jacket layer or a reinforcing outer layer of a metal material on the outside of the jacket. The method of claim 1, And the first and second reinforcing members are made of rod-shaped metal or nonmetal. In optical fiber cable, A core composed of a first reinforcing member having a high modulus of elasticity and positioned in the center of the optical fiber cable, a slot spacer surrounding the first reinforcing member, and a plurality of ribbon optical fibers present in a groove of the slot spacer; ; A jacket made of a plastic material and surrounding the core; A second reinforcement member of a plurality of high modulus modulus materials positioned between the core and the jacket and parallel to the first longitudinal reinforcement member and parallel to the first reinforcement member; And the first and second reinforcing members cooperate with each other to provide the cable with a predetermined tensile stiffness. The method of claim 9, And each of the plurality of second reinforcing members is disposed symmetrically to each other without being intentionally twisted. The method of claim 9, And the first and second reinforcing members are made of rod-shaped metal or nonmetal.