KR200318547Y1 - Loose Tube Optical Cable - Google Patents

Abstract

The present invention relates to a loose tube type optical cable. The loose tube type optical cable according to the present invention comprises: four or less cable assembly units (loose tube optical fiber units or inclusions) twisted in a longitudinal direction with a central tension member; A cable sheath for longitudinally wrapping a cable core assembly comprising a central tension member and a cable assembly unit; It characterized in that it comprises any one selected from the group consisting of a fibrous tensile reinforcing member surrounding the cable core assembly, a wire-like tensile reinforcing member and an annular tensile reinforcing member formed on the cable shell. According to the present invention, it is possible to reduce the outer diameter and weight of the optical cable by compactly configuring the structure of the optical cable by eliminating unnecessary inclusions, and tensile stress occurs in the optical cable itself because the central tension member and the tension reinforcement member are not twisted with the cable assembly unit. It can be minimized, and by providing a separate tensile reinforcing member in addition to the central tension member it is possible to meet the tensile strength requirements of the optical cable.

Description

Loose Tube Optical Cable

The present invention relates to a loose tube type optical cable, and more particularly, to a loose tube type optical cable having an improved structure capable of reducing the outer diameter and weight of the optical cable by compactly constructing the optical cable structure while satisfying the tensile strength requirement of the optical cable. .

In general, a loose tube type optical cable includes a plurality of optical fiber units (hereinafter, referred to as a loose tube optical fiber unit) in which as many fiber core wires as required in a metal or plastic loose tube are mounted together with a jelly compound. It has a structure assembled in the longitudinal direction on the outer periphery of the center tension line located in the center. At this time, the plurality of optical fiber units are gathered around the center tensile line by helical twist or SZ twist to minimize the stress caused by the optical fiber due to the bending of the optical cable during the installation or winding of the optical cable.

Conventional loose tube type optical cables generally have a 1 + 5 structure or a 1 + 6 structure in which five or six loose tube optical fiber units are assembled in a helical or SZ twist around a central tension line. However, when the number of optical fiber units required in a loose tube type optical cable having a 1 + 5 structure or a 1 + 6 structure is less than 5 or 6, the remaining unnecessary optical fiber units are replaced with inclusions in order to maintain a circular cross section of the optical cable. For example, as shown in FIG. 1, the optical fiber unit 30 required in the loose tube type optical cable 10 having a 1 + 6 structure in which six optical fiber units 30 are gathered around one central tension line 20 is formed. If the number is two, four unnecessary optical fiber units are replaced with inclusions 40. That is, in the case of a loose tube type optical cable 10 having a 1 + 6 structure, if the number of necessary optical fiber units 30 is 6 steps smaller, the units and inclusions may be 5: 1, 4: 2, 3: 3, 2: 4 or Gather around the central tension line 20 at a ratio of 1: 5.

By the way, in the above case, the cross section of the optical cable 10 is maintained in a circular shape through the insertion of the inclusions 40, but it is inconvenient to use the inclusions 40, which are not necessary, and the optical fiber unit ( Although the number of 30 is reduced, there is a problem that the outer diameter and the weight of the optical cable 10 are not substantially reduced by the use of the inclusions 40.

On the other hand, unlike the above-described conventional technique for inserting unnecessary inclusions for maintaining the circular shape of the loose tube type optical cable, the same number of optical fiber units (3 or 4) as the loose tube type optical cable having a 1 + 5 structure or a 1 + 6 structure An example of reducing the outer diameter and weight of an optical cable by excluding unnecessary inclusions is disclosed by PCT International Publication WO 02/079846 "Optical Fiber Cable". This technology consists of three or four optical fiber units made of stainless steel with a plurality of tensile wires made of aluminum in the longitudinal direction to form a cable core assembly to satisfy the tensile strength of the optical cable while reducing the outer diameter and weight of the optical cable. Characterized in that.

However, the above technical configuration is difficult to apply when the tube material of the optical fiber unit is plastic. Because if the tube is made of plastic, twisting the length of the loose tube and the metallic material together in the longitudinal direction together causes a squeezing phenomenon in the loose tube located between the tensile lines due to the relative difference in strength and elasticity. This is because the characteristics of the optical fiber are deteriorated or it is difficult to form a regular three-dimensional twisted array in the longitudinal direction, and furthermore, the workability is not good because the tension of the optical cable is not easily adjusted during the installation work.

The limitation of the technique disclosed in the above-mentioned International Publication WO 02/079846 is not overcome even by changing the material of the tensile wire to the fiber-reinforced plastic which is used as the tension member of the optical cable. Because fiber-reinforced plastics have a high elastic force and tend to restore to their original shape when deformed, they are difficult to maintain the twisted state of an assembly composed of tensile lines and loose tube optical fiber units, If you don't lengthen it, it won't twist normally. Of course, it is also possible to artificially maintain the twisted state of the aggregate by using a binder, but in this case, tensile stress is induced on the aggregate, thereby deteriorating signal characteristics during optical signal transmission or damaging the loose tube itself.

On the other hand, when the tension line and the tube made of fiber reinforced plastic are made of fiber-reinforced plastic, the twisting pitch is increased when the fiber unit is formed in the longitudinal direction, thereby causing a problem in the temperature characteristics of the optical cable. Therefore, in order to solve this problem, it is necessary to consider the fact that there is a difficulty in cable design, in which the parameters of the optical fiber unit such as EFL (Extended Fiber Length) and loose tube diameter must be strictly selected.

Accordingly, the technical problem to be achieved by the present invention is to have the same number of loose tube optical fiber units as the conventional 1 + 5 structure or 1 + 6 structure and to have a smaller optical cable transition weight, and to provide a loose tube optical fiber unit by the optical cable tension member. It is to provide a loose tube type optical cable having an improved structure that can satisfy the tensile strength requirements of the optical cable while minimizing the impact.

The following drawings attached to this specification are illustrative of the preferred embodiments of the present invention, and together with the detailed description of the present 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 of a loose tube type optical cable having a conventional 1 + 6 structure.

2A and 2B are cross-sectional views of a loose tube optical cable according to a first embodiment of the present invention.

3A and 3B are cross-sectional views of a loose tube optical cable according to a second embodiment of the present invention.

4A and 4B are cross-sectional views of a loose tube optical cable according to a third embodiment of the present invention.

Figures 5a to 5c, and Figure 6 is a cross-sectional view of the optical cable according to the present invention is provided with two or more tensile reinforcing members.

According to an aspect of the present invention for achieving the above technical problem, the loose tube type optical cable, the central tension member extending in the longitudinal direction from the center of the optical cable; A plurality of cable assembly units including at least one loose tube optical fiber unit twisted in contact with the outer circumference of the central tension member in a longitudinal direction; A fibrous tension reinforcement member surrounding a circumference of a cable core assembly including the central tension member and the cable assembly unit; And a cable sheath covering the outer periphery of the cable core assembly enclosed by the fibrous tension reinforcing member in the longitudinal direction, wherein the number of the cable assembly units is 4 or less, and each cable assembly unit is located in the vicinity of the other two. It is characterized by facing the cable assembly unit and substantially touching.

According to one aspect of the present invention, a loose tubular optical cable includes: a wire-shaped tensile reinforcing member formed in the cable shell and extending in a longitudinal direction and facing substantially 180 degrees with respect to the central tension member; An annular tension reinforcement member formed in the cable jacket and substantially coaxial with the central tension member; Or a combination thereof.

According to another aspect of the present invention for achieving the above technical problem, a loose tube type optical cable, the central tension member extending in the longitudinal direction from the center of the optical cable; A plurality of cable assembly units including at least one loose tube optical fiber unit extending in the longitudinal direction from the outer circumference of the central tension member; A cable sheath that longitudinally wraps an outer circumference of a cable core assembly including the central tension member and the plurality of cable assembly units; And a wire-shaped tension reinforcing member formed in the cable sheath and extending in a lengthwise direction substantially 180 degrees with respect to the central tension member. It includes, but the number of the cable assembly unit is less than 4, each cable assembly unit is characterized in that the substantially opposite and facing the other two cable assembly unit located in the immediate vicinity.

According to another aspect of the present invention, a loose tubular optical cable may further include an annular tensile reinforcing member formed in the cable shell and formed substantially coaxially with the central tension member.

According to another aspect of the present invention, there is provided a loose tube optical fiber including: a central tension member extending in a longitudinal direction from the center of the optical cable; A plurality of cable assembly units including at least one loose tube optical fiber unit extending in a lengthwise direction from an outer circumference of the central tension member; A cable sheath that longitudinally wraps an outer circumference of a cable core assembly including the central tension member and the plurality of cable assembly units; And an annular tensile reinforcement member formed in the cable shell and substantially coaxial with the central tension member. It includes, but the number of the cable assembly unit is less than 4, each cable assembly unit is characterized in that the substantially opposite and facing the other two cable assembly unit located in the immediate vicinity.

In the present invention, the cable assembly unit refers to a component of the present invention which is twisted in a longitudinal direction with a central tension member to form the cable core assembly, and may in some cases refer to a loose tube optical fiber unit or an inclusion. You may. In the present invention, the material of the loose tube is preferably plastic.

In the present invention, the cable core assembly is a 1 + 3 structure,

The plurality of cable assembly unit is three loose tube optical fiber unit; Two loose tube optical fiber units and one inclusion; Or one loose tube optical fiber unit and two inclusions.

In the present invention, the cable core assembly is a 1 + 4 structure,

The plurality of cable assembly unit is four loose tube optical fiber unit; Three loose tube optical fiber units and one inclusion; Two loose tube optical fiber units and two inclusions; Or three loose tube optical fiber units and one inclusion.

In the present invention, the fibrous tensile reinforcing member and the annular tensile reinforcing member may be made of glass yarn, aramid yarn or a combination thereof.

In the present invention, the wire-type tensile reinforcing member may be made of fiber-reinforced plastic, steel wire, plastic coated steel wire, or a combination thereof.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. Prior to this, the terms or words used in this specification and claims should not be construed as being limited to their usual or dictionary meanings, and the inventors will properly describe the concept of terms in order to best explain their invention in the best possible way. Based on the principle that it 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 ideas 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.

2A and 2B are cross-sectional views of a loose tube type optical cable having a 1 + 3 structure and a 1 + 4 structure, respectively, according to the first embodiment of the present invention.

2A and 2B, the loose tube type optical cables A1 and B1 according to the first embodiment of the present invention have a central tension member 50 extending in the longitudinal direction from the center of the optical cables A1 and B1, and Three (1 + 3 structure) or four (1 + 4 structure) optical fiber units 60, which are a plurality of cable assembly units which are twisted in the longitudinal direction from the outer circumference of the central tension member 50, and the central tension The outer periphery of the fibrous tension reinforcement member 80 surrounding the cable core assembly 70 including the member 50 and the optical fiber unit 60 and the cable core assembly 70 wrapped by the fibrous tension reinforcement member 80. It includes a cable sheath 90 is wrapped in the longitudinal direction. Here, the term cable assembly unit collectively refers to a cylindrical assembly unit that is twisted in the longitudinal direction and extends from the outer circumference of the central tension member 50, in the first embodiment of the present invention, the optical fiber unit 60 Refers to.

The optical fiber unit 60 is a hygroscopic filler 110 contained in a loose tube made of plastic, such as polyethyleneterephthalate (PBT), polyethylene (PE), and polyvinylchloride (PVC), such as a predetermined number of optical fiber core wires 100 in a jelly compound. It has a structure mounted with this EFL (Extended Fiber Length), and is gathered in the longitudinal direction by twisting helical or SZ on the outer circumference of the central tension member 50. In this case, even if bending occurs in the optical cables A1 and B1 when the optical cables A1 and B1 are laid or the drum is wound, stress caused by the optical fiber core 100 mounted in the loose tube can be minimized. The plurality of optical fiber units 60 are assembled in the longitudinal direction in contact with the outer periphery of the central tension member 50, each optical fiber unit 60 is substantially 60 degrees (1 + 3 structure) with the other two optical fiber units 60 Or face to face at an angle of 90 degrees (1 + 4 structure). The optical cables A1 and B1 according to the present invention have such a structure, so that the optical cables having the same number of optical fiber units (3 or 4) than the conventional 1 + 5 or 1 + 6 optical cables (10 in FIG. 1). There is an advantage that the outer diameter and weight of the cable is reduced. The structure of the improved optical cables A1 and B1 according to the present invention reduces the manufacturing, transportation, and installation costs of the optical cables A1 and B1.

The central tension member 50 is located in a space defined by three (1 + 3 structure) or four (1 + 4 structure) optical fiber unit 60, the optical fiber unit 60 and the outer periphery Do not twist together in the longitudinal direction. The central tension member 50 may be made of fiber-reinforced plastic, steel wire, plastic coated steel wire or a combination thereof. By the way, even if the center tension member 50 is made of a material or a metal material with a large elastic force in the present invention, unlike the prior art, the center tension member 50 is not twisted together with the optical fiber unit 60 in the longitudinal direction In the loose tube located between the central tension member 50, the pressing phenomenon may be prevented or the tube itself may be damaged.

On the other hand, when the outer diameter of the optical fiber unit 60 and the material of the central tension member 50 is the same as the conventional optical cable (10 in Fig. 1) of the 1 + 5 structure or 1 + 6 structure, the center tension member The space where 50 can be located is smaller than that of the conventional 1 + 5 or 1 + 6 optical cable (10 in FIG. 1). Accordingly, the outer diameter of the central tension member 50 has a smaller value than that of the conventional optical cable (10 in FIG. 1), so that the central tension member 50 can withstand the drum winding or installation of the optical cables A1 and B1. The tensile stress which is present becomes smaller than the conventional optical cable (10 in FIG. 1).

The decrease in the tensile strength characteristics of the optical cables A1 and B1 due to the decrease in the outer diameter of the central tension member 50 is compensated by the fibrous tension reinforcement member 80. The thickness of the fibrous tensile reinforcing member 80 provided to reinforce the tensile strength characteristics of the optical cables A1 and B1 may compensate for the decrease in the tensile strength characteristics of the optical cables A1 and B1 due to the reduction in the outer diameter of the central tensile member 50. It is desirable that it is enough. The fibrous tensile reinforcing member 80 is preferably transverse winding and / or longitudinal so as to surround the outer periphery of the cable core assembly 70, and may be any fibrous material having a tensile strength characteristics, but in the present invention glass yarn, aramid yarn Or a combination thereof.

Although not shown in detail in the drawings, the cable sheath 90 may be made of a single layer structure made of only an outer sheath layer, or may be made of a multi-layered structure such as an inner sheath layer / laminated moisture-proof layer / outer sheath layer of aluminum. . However, the present invention is not limited thereto, and various modifications and applications are possible within the scope of the technical idea known in the technical field to which the present invention belongs. The inner sheath layer or the outer sheath layer is preferably made of a plastic resin such as PBT, PE, PVC, flame free flame retardant thermoplastic, polyurethane.

Optical cable (A1, B1) according to the first embodiment of the present invention is a hygroscopic taping layer for preventing damage to the optical fiber core wire 100 mounted in the loose tube by water penetration; Hygroscopic fillers (eg, jelly compounds); A heat insulating layer made of a metal material to prevent a temperature drop of the optical cables A1 and B1; And it may further include any one or a combination thereof selected from the group consisting of a cable core assembly binder on the outer periphery of the cable core assembly 70. In addition, when the number of optical fiber units 60 required in the optical cables A1 and B1 according to the first embodiment of the present invention is 2 or less, the unnecessary optical fiber units 60 may be replaced with inclusions (not shown). Even in this case, the optical cable according to the present invention has a smaller outer diameter and weight when compared with the conventional 1 + 5 or 1 + 6 optical cable (10 in FIG. 1) provided that the number of the optical fiber units 60 is the same. Have When the optical fiber unit 60 is replaced with an inclusion, the optical fiber unit 60 and the inclusion constitute a plurality of cable assembly units according to the present invention.

3A and 3B are cross-sectional views of a loose tube type optical cable having a 1 + 3 structure and a 1 + 4 structure, respectively, according to a second embodiment of the present invention.

3A and 3B, the loose tube type optical cables A2 and B2 according to the second embodiment of the present invention are the tensile reinforcing members, and the fibrous tensile reinforcing members of the first embodiment described above (80 in FIGS. 2A and 2B). Instead, it is provided with a cable-like tensile reinforcing member 120 formed in the cable jacket 90 and extending in the lengthwise direction substantially 180 degrees with respect to the central tension member 50. In the second embodiment of the present invention, the plurality of cable assembly unit according to the present invention is a loose tube optical fiber unit 60 is extended in the longitudinal direction from the outer periphery of the central tension member (50).

The wire-type tensile reinforcing member 120 is preferably provided in a substantially point-symmetrical with respect to the central tensile member 50 in order to be able to efficiently distribute the tensile stress applied to the optical cables (A2, B2). The wire-type tensile reinforcing member 120 may be any material that can maintain the circular shape as well as the tensile strength characteristics, in the embodiment of the present invention, fiber reinforced plastic, steel wire, steel wire coated with plastic or It is preferable to consist of these combinations.

The material and the outer diameter of the wire-type tensile reinforcing member 120, the optical cable (A2, B2) according to the present invention is a central tension member (10) compared to the optical cable (10 in Figure 1) of the conventional 1 + 5 structure or 1 + 6 structure ( Since the outer diameter of 50) is reduced and the tensile strength characteristics of the optical cables A2 and B2 are lowered, it is desirable to determine this in consideration of compensation.

The cable sheath 90 may be of a single layer structure or a multilayer structure as in the first embodiment. In particular, in the case of a multilayer structure, the wire type tensile reinforcing member 120 is provided in the inner sheath layer and / or the outer sheath layer. . The wire-like tensile reinforcing member 120 is preferably inserted into the inner sheath layer and / or the outer sheath layer in the sheath extrusion process during the manufacture of the optical cables A2 and B2.

If the number of optical fiber units 60 required in the optical cables A2 and B2 according to the second embodiment of the present invention is 2 or less, the unnecessary optical fiber units 60 may be replaced with inclusions (not shown). Even in this case, the optical cables A2 and B2 according to the present invention are further provided as compared with the conventional 1 + 5 or 1 + 6 optical cables (10 in FIG. 1) provided that the number of the optical fiber units 60 is the same. It has a small outer diameter and weight. When the optical fiber unit 60 is replaced with an inclusion, the optical fiber unit 60 and the inclusion constitute a plurality of cable assembly units according to the present invention.

4A and 4B are cross-sectional views of a loose tube type optical cable having a 1 + 3 structure and a 1 + 4 structure, respectively, according to a third embodiment of the present invention.

4A and 4B, the loose tube type optical cables A3 and B3 according to the third embodiment of the present invention are the tensile reinforcing members, and the fibrous tensile reinforcing members of the first embodiment described above (80 in FIGS. 2A and 2B). Instead, it includes a fibrous annular reinforcement member 130 formed in the cable shell 90 and formed substantially coaxially with the central tension member 50. In a third embodiment of the present invention, the plurality of cable assembly unit according to the present invention is a loose tube optical fiber unit 60 that is extended in the longitudinal direction from the outer periphery of the central tension member (50).

The annular tensile reinforcing member 130 is preferably provided in a substantially point-symmetrical with respect to the central tension member 50 in order to be able to disperse the tensile stress applied to the optical cables (A3, B3). The annular tensile reinforcing member 130 may be any fibrous material having tensile strength, but in the present invention, it is preferable that the annular tensile reinforcing member 130 is made of glass yarn, aramid yarn, or a combination thereof.

The material and thickness of the annular tensile reinforcing member 130, the optical cable (A3, B3) according to the present invention is a central tension member 50 compared to the optical cable (10 in Figure 1) of the conventional 1 + 5 structure or 1 + 6 structure ), The outer diameter of the optical fiber (A3, B3) is reduced due to the decrease in the outer diameter of the optical cable (A3, B3).

The cable sheath 90 may be of a single layer structure or a multilayer structure, as in the first embodiment. In particular, in the case of a multilayer structure, the annular tensile reinforcing member 130 may be selectively provided in the inner sheath layer and / or the outer sheath layer. Can be. The annular tensile reinforcing member 130 is preferably transversely and / or seeded into the inner sheath layer and / or the outer sheath layer in the sheath extrusion process during the manufacture of the optical cables A3 and B3.

If the number of optical fiber units 60 required in the optical cables A3 and B3 according to the third embodiment of the present invention is 2 or less, the unnecessary optical fiber units 60 may be replaced with inclusions (not shown). Even in this case, the optical cables A3 and B3 according to the present invention are further provided as compared with the conventional 1 + 5 or 1 + 6 optical cables (10 of FIG. 1) provided that the number of the optical fiber units 60 is the same. It has a small outer diameter and weight. When the optical fiber unit 60 is replaced with an inclusion, the optical fiber unit 60 and the inclusion constitute a plurality of cable assembly units according to the present invention.

The optical cable according to the present invention may include two or more tensile reinforcing members by combining the structures according to the first to third embodiments described above. Hereinafter, the optical cable according to the present invention having a 1 + 3 structure will be described as an example. However, it can be applied to the optical cable according to the present invention having a 1 + 4 structure in substantially the same manner to those skilled in the art.

More specifically, the optical cable A1 according to the first embodiment of the present invention, in addition to the fibrous tensile reinforcing member 80 as shown in Figures 5a, 5b and 5c and the wire-type tensile reinforcing member 120 and / Alternatively, the annular tensile reinforcing member 130 may be further included. At this time, when the wire type tensile reinforcing member 120 and the annular tensile reinforcing member 130 is further provided in the optical cable A1 according to the first embodiment of the present invention, as shown in FIG. ) Is implemented in a multi-layer structure including the inner sheath layer 140 and the outer sheath layer 150, it is preferable that the wire-like tensile reinforcing member 120 and the annular tensile reinforcing member 130 is provided in different sheath layers. .

As shown in FIG. 6, the optical cable A1 according to the second exemplary embodiment of the present invention may further include an annular tensile reinforcing member 130 provided in the cuff shell 90 as well as the wire type tensile reinforcing member 120. Can be.

As described above, when the optical cable according to the present invention is provided with two or more types of tensile reinforcing members, it is possible to further improve the tensile strength characteristics of the optical cable, thereby further reducing the optical properties due to the tensile stress caused during drum winding or laying of the optical cable. It can be effectively prevented.

Although the technical idea of the present invention has been described by the limited embodiments and the drawings, the present invention is not limited thereto, and the technical idea of the present invention and the technical idea of the present invention are given by those skilled in the art to which the present invention pertains. Various modifications and variations are possible within the scope of equivalents of the claims to be described.

According to an aspect of the present invention, while having the same number of loose tube optical fiber units as the conventional 1 + 5 structure or 1 + 6 structure, it is possible to exclude unnecessary inclusions to reduce the outer diameter and weight of the optical cable.

According to another aspect of the present invention, since the central tension member and the tension reinforcement member are not twisted together with the loose tube optical fiber unit, it is possible to prevent the optical properties of the optical fiber from being degraded or the loose tube is damaged by the tensile stress caused by the optical cable itself. .

According to another aspect of the present invention, by providing a separate tensile reinforcing member in addition to the central tension member it is possible to meet the tensile strength requirements required for the loose tube type optical cable.

Claims (29)

In loose tube type optical cable, (a) a central tension member extending in the longitudinal direction from the center of the optical cable; (b) a plurality of cable assembly units including at least one loose tube optical fiber unit extending in a lengthwise direction from an outer circumference of the central tension member; (c) a fibrous tensile reinforcement member surrounding a circumference of a cable core assembly including the central tension member and the cable assembly unit; And (d) a cable sheath for longitudinally wrapping the outer periphery of the cable core assembly wrapped by the fibrous tension reinforcing member; The number of the cable assembly unit is 4 or less, each cable assembly unit is a loose tube type optical cable, characterized in that the substantially opposite and facing the other two cable assembly unit located in the immediate vicinity. The method of claim 1, A loose tube type optical cable, characterized in that the tube of the loose tube optical fiber unit is made of plastic. The method of claim 1, The cable core assembly is a 1 + 3 structure, The plurality of cable assembly unit is a loose tube optical fiber unit, characterized in that consisting of three loose tube optical fiber unit, two loose tube optical fiber unit and one inclusion, or one loose tube optical fiber unit and two inclusions. The method of claim 1, The cable core assembly is 1 + 4 structure, The plurality of cable assembly units are composed of four loose tube optical fiber units, three loose tube optical fiber units and one inclusion, two loose tube optical fiber units and two inclusions, or three loose tube optical fiber units and one inclusion. A loose tube type optical cable characterized by the above-mentioned. The method of claim 1, And a wire-shaped tensile reinforcing member formed in said cable sheath and extending in a longitudinal direction substantially 180 degrees with respect to said central tension member. The method of claim 5, The wire-type tensile reinforcing member is a fiber-reinforced plastic, steel wire, loose tube-type optical cable, characterized in that made of a plastic coated steel wire or an assembly thereof. The method according to claim 1 or 5, And an annular tensile reinforcing member formed in said cable shell and substantially coaxial with said central tension member. The method of claim 7, wherein The annular tensile reinforcing member is a loose tube type optical cable, characterized in that made of glass yarn, aramid yarn or a combination thereof. The method of claim 1, And said plurality of cable assembly units are helical or SZ twisted in the longitudinal direction at the outer circumference of said central tension member. In loose tube type optical cable, (a) a central tension member extending in the longitudinal direction from the center of the optical cable; (b) a plurality of cable assembly units including at least one loose tube optical fiber unit extending in a lengthwise direction from an outer circumference of the central tension member; (c) a cable sheath surrounding the outer circumference of the cable core assembly including the central tension member and the plurality of cable assembly units in a longitudinal direction; And (d) a wire-shaped tension reinforcing member formed in the cable sheath and extending in a longitudinal direction substantially 180 degrees with respect to the central tension member; Including, The number of the cable assembly unit is 4 or less, each cable assembly unit is a loose tube type optical cable, characterized in that the substantially opposite and facing the other two cable assembly unit located in the immediate vicinity. The method of claim 10, A loose tube type optical cable, characterized in that the tube of the loose tube optical fiber unit is made of plastic. The method of claim 10, The cable core assembly is a 1 + 3 structure, The plurality of cable assembly unit is a loose tube optical fiber unit, characterized in that consisting of three loose tube optical fiber unit, two loose tube optical fiber unit and one inclusion, or one loose tube optical fiber unit and two inclusions. The method of claim 10, The cable core assembly is 1 + 4 structure, The plurality of cable assembly units are composed of four loose tube optical fiber units, three loose tube optical fiber units and one inclusion, two loose tube optical fiber units and two inclusions, or three loose tube optical fiber units and one inclusion. A loose tube type optical cable characterized by the above-mentioned. The method of claim 10, The wire-type tensile reinforcing member is a fiber-reinforced plastic, steel wire, a loose tube type optical cable, characterized in that made of a plastic coated steel wire or a combination thereof. The method of claim 10, Loose tube-type optical cable, characterized in that it further comprises a fibrous tensile strength reinforcing member for wrapping the outer periphery of the cable core assembly in the longitudinal direction The method of claim 13, The fibrous tensile reinforcing member is a loose tube type optical cable, characterized in that consisting of glass yarn, aramid yarn, or a combination thereof. The method according to claim 10 or 15, And an annular tensile reinforcing member formed in said cable shell and substantially coaxial with said central tension member. The method of claim 17, The annular tensile reinforcing member is a loose tube type optical cable, characterized in that made of glass yarn, aramid yarn, or a combination thereof. The method of claim 10, And said plurality of cable assembly units are helical or SZ twisted at the outer periphery of said central tension member. In loose tube type optical cable, (a) a central tension member extending in the longitudinal direction from the center of the optical cable; (b) a plurality of cable assembly units including at least one loose tube optical fiber unit extending in a lengthwise direction from an outer circumference of the central tension member; (c) a cable sheath surrounding the outer circumference of the cable core assembly including the central tension member and the plurality of cable assembly units in a longitudinal direction; And (d) an annular tension reinforcement member formed in the cable jacket and substantially coaxial with the central tension member; Including, The number of the cable assembly unit is 4 or less, each cable assembly unit is a loose tube type optical cable, characterized in that the substantially opposite and facing the other two cable assembly unit located in the immediate vicinity. The method of claim 20, A loose tube type optical cable, characterized in that the tube of the loose tube optical fiber unit is made of plastic. The method of claim 20, The cable core assembly is a 1 + 3 structure, The plurality of cable assembly unit is a loose tube optical fiber unit, characterized in that consisting of three loose tube optical fiber unit, two loose tube optical fiber unit and one inclusion, or one loose tube optical fiber unit and two inclusions. The method of claim 20, The cable core assembly is 1 + 4 structure, The plurality of cable assembly units are composed of four loose tube optical fiber units, three loose tube optical fiber units and one inclusion, two loose tube optical fiber units and two inclusions, or three loose tube optical fiber units and one inclusion. A loose tube type optical cable characterized by the above-mentioned. The method of claim 20, The annular tensile reinforcing member is a loose tube type optical cable, characterized in that made of glass yarn, aramid yarn, or a combination thereof. The method of claim 20, Loose tube-type optical cable, characterized in that it further comprises a fibrous tensile strength reinforcing member for wrapping the outer periphery of the cable core assembly in the longitudinal direction The method of claim 25, The fibrous tensile reinforcing member is a loose tube type optical cable, characterized in that consisting of glass yarn, aramid yarn, or a combination thereof. The method of claim 20 or 25, And a wire-shaped tensile reinforcing member formed in said cable sheath and extending in a longitudinal direction substantially 180 degrees with respect to said central tension member. The method of claim 27, The wire-type tensile reinforcing member is a fiber-reinforced plastic, steel wire, loose tube-type optical cable, characterized in that made of a plastic reinforced steel wire or a combination thereof. The method of claim 20, And said plurality of cable assembly units are helical or SZ twisted at the outer periphery of said central tension member.