KR20040088888A - Metallic optical cable having circular structure using loose tube optical fiber unit - Google Patents

Abstract

PURPOSE: A metallic optical cable is provided to achieve improved advantages of installation of optical cable by reducing the outer diameter of the cable, and reduce manufacturing procedures by eliminating the process of coating an external tension member. CONSTITUTION: A metallic optical cable comprises a tension resistant tension wire(41) made of a metallic material and extended in a lengthwise direction from the center of an optical cable; a loose tube optical fiber unit(44) and a metallic tension rod wire(50) twisted in a lengthwise direction, substantially covering the outer surface of the tension resistant tension wire, such that the loose tube optical fiber unit and the metallic tension rod wire cooperate with the tension resistant tension wire so as to constitute a cable core assembly; and a cable coating(48) made of a plastic resin, and coated along the outer surface of the cable core assembly.

Description

METALLIC OPTICAL CABLE HAVING CIRCULAR STRUCTURE USING LOOSE TUBE OPTICAL FIBER UNIT}

The present invention relates to a metal optical cable, and more particularly, to a metal optical cable having a circular structure in which a loose tube optical fiber unit is twisted together with a metallic tensile wire and assembled on the outer periphery of the tensile tension wire.

Optical cables, also called fiber optic cables, are commonly used to convert electrical signals into light signals and pass them through optical fibers. Optical cables are classified in various ways according to their structure and environment. In particular, optical cables installed in the air are called overhead cables or overhead cables.

The overhead cable may be installed to hang using a hanger on a pre-installed support line, but in recent years, a cable and a support line are often integrated and manufactured, which is called a self supporting cable (SS cable). Call. In addition, the self-supporting cable is configured to connect the outer sheath of the cable and the outer sheath of the support line through the narrowed portion, and sometimes the above-described cable sheath and the support sheath sheath are surrounded by a lashing wire.

First, Figure 1 shows an example of a self-supporting cable according to the prior art. The self-supporting cable shown in FIG. 1 has a tension tension line 1 at a central position, and the tension tension line 1 extends longitudinally from the center of the cable. The tensile tension line 1 is generally made of fiberglass reinforced plastic (FRP). At least one optical fiber unit 4 is disposed on the outer circumferential surface of the tensile tension line 1. The optical fiber unit 4 has a structure in which a plurality of optical fibers 2 are mounted with a predetermined EFL (Extended Fiber Length) in a hygroscopic material such as jelly compound 5 contained in the loose tube 3. This optical fiber unit 4 is hereinafter referred to as a loose tube optical fiber unit. In addition, in some cases, the inclusion 10 may be disposed together with the optical fiber unit 4 in order to keep the cross section of the optical cable circular in the tension tension line 1. Inclusion 10 is made of a plastic resin, such as polyethylene, the use of the inclusion 10 is optionally determined as needed. These inclusions 10 are generally made to be the same size as the optical fiber unit 4, and form the same circumference with the optical fiber unit 4 around the tensile tension line 1.

The optical fiber unit 4 and the inclusion 10 are tightly bound by the binder 6. The binder 6 is generally made of aramid yarns, polyester yarns, polyester films and the like. On the binder 6, an external tension member 7 made of a non-metallic material is provided in a transverse winding or in the form of being inserted. On the outer tension member 7 is provided a cable sheath 8 made of a plastic resin such as polyvinylchloride or polyethylene. A gap in the cable sheath 8 may be filled with a separate filler 9.

The self-supporting optical cable having the above-described structure additionally transversely or longitudinally inserts a nonmetallic external tension member 7 on the outside of the binder 6 to coat the cable sheath 8. Therefore, in the above-described prior art, an increase in the diameter of the optical cable by the external tension member 7 is inevitable.

Figure 2 shows another type of self-supporting optical cable according to the prior art. The optical cable shown in FIG. 2 is generally the same as that shown in FIG. 1, except that a separate support line is connected to the cable. That is, the support line in which the plurality of tension lines 8b twisted in the longitudinal direction are inserted in the outer shell 8a is coupled to the optical cable of FIG.

While the optical cable of FIG. 2 has the same disadvantages as the optical cable of FIG. 1, the overall structure is configured in an eight-character shape, and has a structural limitation in reducing the outer diameter.

Figure 3 shows another example of a self-supporting optical cable according to the prior art. While the optical cable shown in FIGS. 1 and 2 is a structure in which a plurality of optical fiber units are assembled in the longitudinal direction, the optical cable shown in FIG. 3 is a single unit structure in which only one optical fiber unit is provided.

In the optical cable of FIG. 3, a single optical fiber unit wrapping a plurality of optical fibers 12 with a loose tube 13 is disposed at the center. On the outside of the loose tube 13, an outer tension member 17 of a nonmetallic material, such as the optical cable shown in FIG. Lose.

Since the single unit optical cable is provided with only one optical fiber unit, it does not have a tensile tension line as shown in FIGS. 1 and 2. Therefore, in order to use the optical cable of FIG. 3 as a processing cable, it is necessary to connect a separate support line. The support line consists of a sheath 18a and a number of tension lines 18b longitudinally twisted therein and longitudinally twisted.

Since the optical cable having the above-described structure has only one optical fiber unit, the overall outer diameter can be reduced. However, since the optical cable does not have a tensile line therein, a supporting line must be provided to reinforce the weakened tensile force. Therefore, the single unit optical cable has a disadvantage that space efficiency is reduced when laying the pipeline.

Therefore, the present invention was devised to solve the above problems, by using a tensile tension line of the center as a metal material and by replacing the inclusions inserted for maintaining the circular shape of the optical cable with a tensile wire material of a separate external tension material It is an object of the present invention to provide a metal optical cable capable of self-supporting a circular structure capable of exerting a sufficient tensile force with a small outer diameter without using or fabricating a support line integrally.

The following drawings attached to this specification are illustrative of preferred embodiments of the present invention, and together with the detailed description of the invention to serve to further understand the technical spirit of the present invention, the present invention is a matter described in such drawings It should not be construed as limited to

1 is a cross-sectional view showing an example of a self-supporting optical cable according to the prior art.

2 is a cross-sectional view showing another example of a self-supporting optical cable according to the prior art.

3 is a cross-sectional view showing still another example of a self-supporting optical cable according to the prior art.

4 is a sectional view showing a metal optical cable according to the present invention;

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

41. Tensile strength of tension line 42. Optical fiber 43. Loose tube

44 .. Fiber optic unit 48. Cable sheath 50. Metallic tensile wire

Metal-type optical cable according to the present invention for achieving the above object is a tensile tension line of a metal material extending in the longitudinal direction from the center of the optical cable; A metallic tube and a loose tube optical fiber unit including at least one optical fiber twisted in a longitudinal direction substantially enclosing the outer circumference of the tensile tension line and forming a cable core assembly together with the tensile tension line; And a cable sheath made of plastic resin surrounding the outer circumference of the cable core assembly.

Preferably, the cable core assembly further includes an inclusion.

Also preferably, the number of metallic tensile wires may be determined in consideration of the tensile force of the optical cable, and an inclusion made of plastic resin may be further disposed on an outer circumferential surface of the tensile wire in which the optical fiber unit and the metallic tensile wire are not disposed.

In this case, the number of the metallic tensile wire is preferably two or more.

In addition, it is preferable that the cable core assembly is substantially in contact with the inner surface of the cable sheath, and it is also preferable that the optical fiber unit and the metallic tensile wire have the same diameter.

In the above-described configuration, the metallic tensile wire is preferably having an outer diameter of 0.6 ~ 6.0 mm, the metallic tensile wire is any one selected from the group consisting of galvanized steel wire, copper wire, iron wire, steel wire and aluminum coated steel wire Is made of a combination of

In addition, the cable jacket preferably has an outer diameter of 0.1 ~ 3 mm, the cable jacket is polyvinyl chloride, halogen-free flame retardant thermoplastic, polyethylene (polyethylene) and polyurethane ( Polyurethane) is selected from the group consisting of.

Preferably, the gap in the cable sheath may include hygroscopic fillers or absorbent fibers.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. Prior to this, terms or words used in the specification and claims should not be construed as having a conventional or dictionary meaning, and the inventors should properly explain the concept of terms in order to best explain their own invention. Based on the principle that can be defined, it should be interpreted as meaning and concept corresponding to the technical idea of the present invention. Therefore, the embodiments described in the specification and the drawings shown in the drawings are only the most preferred embodiment of the present invention and do not represent all of the technical idea of the present invention, various modifications that can be replaced at the time of the present application It should be understood that there may be equivalents and variations.

4 is a cross-sectional view showing the configuration of a metal optical cable according to the present invention.

Referring to Figure 4, the metal optical cable of the present invention has a tensile tension line 41 extending in the longitudinal direction of the optical cable in the center. The tensile tension line 41 is made of a metal material, and minimizes the effect caused on the optical fiber mounted on the optical cable by the tensile stress caused during the drum winding or installation of the optical cable.

On the outer circumferential surface of the tensile tension line 41, a loose tubular optical fiber unit 44 including one or more optical fibers, which are twisted helically or SZ in the longitudinal direction and centered on the tensile tension line 41, is disposed. The optical fiber unit 44 has a structure in which a plurality of optical fibers 42 are mounted in a hygroscopic material, such as a jelly compound, included in the loose tube 43. The loose tube 43 is preferably made of a plastic resin.

The optical cable according to the present invention has at least one optical fiber unit 44. However, not all of the periphery of the tensile tension line 41 is surrounded by the optical fiber unit 44, and a tensile wire 50 made of metal is disposed in place of the optical fiber unit 44 instead of the optical fiber unit 44. .

The metallic tensile wire 50 may be any one selected from the group consisting of galvanized steel wire, copper wire steel wire, iron wire, steel wire and aluminum coated steel wire, or a combination thereof. The metallic tensile wire 50 replaces the inclusions employed in the conventional self-supporting optical cable, and differs from the conventional inclusions in its role. The conventional inclusion functions to protect the optical fiber unit by keeping the cross section of the optical cable circular by simply occupying the position of the optical fiber unit and preventing the cable sheath from being deformed from external impact. However, the metallic tensile wire 50 provided in the optical cable according to the present invention serves to further strengthen the tensile force of the optical cable itself by exhibiting the tensile force peculiar to the metal as well as the above-described inclusions. Therefore, in the related art, an external tension member made of a non-metallic material is required to reinforce the tensile force of the optical cable. However, in the present invention, the external tension member is not required because the metallic tension wire 50 replaces the role of the external tension member.

Two or more metallic tensile wires 50 are preferably used. That is, at least two or more metallic tensile wires 50 are disposed on the outer circumferential surface of the tensile tension wire 41 together with the one or more optical fiber units 44. The outer diameter of the metallic tensile wire 50 is determined in the range of 0.6 ~ 6.0mm. When the outer diameter of the metallic tensile wire 50 is 0.6 mm or less, it is not possible to guarantee a proper level of tensile strength, and when the outer diameter of the metallic tensile wire 50 is 6.0 mm or more, it causes an increase in the outer diameter of the optical cable and reduces the cable outer diameter by introducing the metallic tensile wire 50. It is hard to expect.

Since the metallic tensile wire 50 is resistant to external impact or side pressure, it is advantageous to protect the optical fiber unit 44 disposed at the periphery. In addition, since the metallic tensile wire 50 has a low thermal expansion coefficient of the metal material used and thus is hardly affected by external temperature change, it helps to improve the low / high temperature characteristics of the optical cable.

In addition, in the present invention, the tensile force of the optical cable itself may be adjusted by controlling the number of metallic tensile wires 50. That is, after arranging the required number of optical fiber units 44 on the outer periphery of the tensile tension wire 41 and considering the area where the metallic tensile wire 50 can be placed, the appropriate number of metallic tensile wire 50 and inclusions in the area. It is possible to arrange them together. In this case, the tensile force of the metal optical cable of the present invention is determined by the number of use of the metallic tensile wire (50).

The optical fiber unit 44 and the metallic tensile wire 50 are arranged to form one circumference around the tensile tension wire 41. For this purpose, it is preferable that the optical fiber unit 44 and the metallic tensile wire 50 have the same diameter. Further, the optical fiber unit 44 and the metallic tensile wire 50 are gathered in the longitudinal direction at the outer circumference of the tensile tension wire 41 so as to be twisted in helical or SZ.

The tensile tension wire 41, the optical fiber unit 44 and the metallic tensile wire 50 assembled therein constitute a cable core assembly. Of course, when the inclusions are further gathered on the outer periphery of the tensile tension line 41, the cable core assembly further includes the inclusions.

The cable core assembly is longitudinally wrapped by cable sheath 48. Accordingly, in the present invention, the optical fiber unit 44 and the metallic tensile wire 50 are in substantially contact with the inner surface of the cable jacket 48.

The cable sheath 48 is made of plastic resin, and preferred plastic resins that may be used include polyvinylchloride, halogen free flame retardant thermoplastic, polyethylene or polyurethane. It may be mentioned, but the present invention is not limited thereto.

The cable sheath 48 has a thickness of 0.1-3.0 mm. If the thickness of the outer shell 48 is 0.1 mm or less, it does not properly exhibit the function of the outer shell and causes a disadvantage in reducing workability. In addition, when the thickness of the outer jacket 48 is 3.0 mm or more, the radius of curvature of the cable increases, which may cause problems in laying work.

Gaps in the cable sheath 48 may be filled with hygroscopic fillers or absorbent fibers to prevent moisture from penetrating into the optical cable. As the hygroscopic filler, jelly compound or silicone oil may be used, but the present invention is not limited thereto.

As described above, although the present invention has been described by way of limited embodiments and drawings, the present invention is not limited thereto and is intended by those skilled in the art to which the present invention pertains. Of course, various modifications and variations are possible within the scope of equivalents of the claims to be described.

The metal optical cable according to the present invention does not require a conventional external tension material by the use of a metallic tension wire, and because it retains sufficient tensile strength by the metallic tension wire, it is not necessary to separately provide a support line like a conventional optical cable. Therefore, the optical cable of the present invention has a smaller cable outer diameter than the conventional optical cable, which is advantageous when laying the optical cable.

In addition, the optical cable of the present invention is simplified because the process of covering the external tension material is omitted, thereby making it possible to reduce the manufacturing cost.

Claims (11)

In the metal optical cable, Tensile tension lines made of metal extending in the longitudinal direction from the center of the optical cable; A metallic tube and a loose tube optical fiber unit including at least one optical fiber twisted in a longitudinal direction substantially enclosing the outer circumference of the tensile tension line and forming a cable core assembly together with the tensile tension line; And Metal-type optical cable comprising a cable shell made of a plastic resin surrounding the outer periphery of the cable core assembly. The method of claim 1, The cable core assembly further comprises an inclusion type metal optical cable. The method of claim 1, The number of metallic tensile wires is determined in consideration of the tensile force of the optical cable, The optical fiber unit and the metallic optical cable, characterized in that the inclusion portion made of a plastic resin is further disposed on the outer circumferential surface of the tensile wire is not disposed. The method of claim 1, Metal type optical cable, characterized in that the number of the metallic tensile wires two or more. The method according to any one of claims 1 to 4, And said cable core assembly is substantially in contact with an inner surface of said cable sheath. The method according to any one of claims 1 to 4, And the optical fiber unit and the metallic tensile wire have the same diameter. The method according to any one of claims 1 to 4, The metallic tensile wire is a metal optical cable, characterized in that having an outer diameter of 0.6 ~ 6.0 mm. The method according to any one of claims 1 to 4, The metallic tensile wire is any one or a combination thereof selected from the group consisting of galvanized steel wire, copper wire steel wire, iron wire, steel wire and aluminum coated steel wire. The method according to any one of claims 1 to 4, The cable sheath is a metal optical cable, characterized in that having a thickness of 0.1 ~ 3.0 mm. The method according to any one of claims 1 to 4, The outer sheath of the cable is made of polyvinylchloride, a halogen-free flame retardant thermoplastic, a metal optical cable, characterized in that made of any one selected from the group consisting of polyethylene, polyethylene, and polyurethane. . The method according to any one of claims 1 to 4, Metallic optical cable, characterized in that the hygroscopic filler contains a hygroscopic fiber in the gap in the cable jacket.