Optical cable

Abstract

The present invention relates to an optical cable. More specifically, the present invention relates to a narrow optical cable, with which pneumatic installation in a duct is possible, the cable being provided with an optical fiber ribbon that can be rolled in the width direction, which enables the construction of a large-capacity optical communication network, and having excellent flexibility whilst being able to minimize room-temperature optical loss.

Description

optical cable

[0001] The present invention relates to an optical cable. More specifically, the present invention relates to an optical cable capable of pneumatic installation within a duct, which comprises an optical fiber ribbon capable of widthwise rolling, enabling the construction of a large-capacity optical communication network, and which is a fine-diameter optical cable capable of both superior flexibility and minimizing room-temperature optical loss.

[0002] As demand for communications increases, the need for building optical communication networks using multi-core optical cables is increasing to meet the demands for service diversification, high-speed transmission, large capacity, and multi-channel.

[0003] Multicore optical cables utilize multiple optical units, each comprised of a single optical fiber ribbon, connected in parallel and housed within a binding member. This allows for the simultaneous connection of multiple optical fibers constituting the cable, making it ideal for building large-capacity communications networks.

[0004] Additionally, the multicore optical cable may be configured to include a rollable optical fiber ribbon that can be flexibly deformed by rolling or folding the optical fiber ribbon in the width direction to further increase the number of optical fiber cores accommodated within the same area of ​​the cable.

[0005] Typically, conduits are provided for the installation of various cables, including multicore optical cables. Recently, as conduits become saturated, pneumatic installation of multicore optical cables can be used to efficiently utilize the limited space within the conduits. Pneumatic installation utilizes air pressure to blow cables into ducts installed within the conduit, thereby installing them.

[0006] Meanwhile, during the pneumatic laying process of a multi-core optical cable, physical impacts applied to the optical cable may directly apply stress to the optical fiber ribbon and the optical fibers constituting it, which may result in optical loss of the optical fiber.

[0007] In addition, the cable jacket of an optical cable is a component that protects the optical fibers inside, provides tensile strength, and determines the flexibility of the optical cable, which is one of the important characteristics during pneumatic laying, so it is important to control the outer diameter, thickness, and weight of the cable jacket.

[0008] Therefore, there is a great demand for a thin-diameter optical cable that can be pneumatically installed in a duct, has an optical fiber ribbon that can roll in the width direction, and enables the construction of a large-capacity optical communication network, and has excellent flexibility while minimizing optical loss at room temperature.

[0009] The present invention is an optical cable capable of pneumatic installation in a duct, and has an optical fiber ribbon capable of widthwise rolling, enabling the construction of a large-capacity optical communication network. The object of the present invention is to provide a small-diameter optical cable having excellent flexibility and improved optical loss characteristics.

[0010] In order to solve the above problem, the present invention can provide an optical cable comprising: at least one optical unit comprising a plurality of optical fibers and a tube-shaped binding member for accommodating the plurality of optical fibers; a cable jacket for wrapping the at least one optical unit; and at least four tensile members embedded in the cable jacket in the longitudinal direction of the cable and provided spaced apart from each other in the circumferential direction of the cable jacket; wherein the inner surface of the cable jacket in a cross-section perpendicular to the longitudinal direction has a fluting structure in which a concave portion and a convex portion are repeatedly formed along the circumferential direction.

[0011] Additionally, the plurality of optical fibers may be in the shape of a plurality of rollable optical fiber ribbons capable of widthwise rolling.

[0012] Here, the shape may be such that the inner circumferential surface and the steel portion of the cable jacket are connected in a curved manner in a cross-section perpendicular to the longitudinal direction of the optical cable.

[0013] And, in a cross-section perpendicular to the longitudinal direction of the cable jacket, the ratio of the angle forming the inner circumferential surface from the center of the cable to the angle forming the yoke may be 1.10 to 2.00.

[0014] Furthermore, the outer circumferential surface of the cable jacket may have a circular cross-section in a cross-section perpendicular to the longitudinal direction of the optical cable.

[0015] Additionally, the outer surface of the cable jacket may have a structure in which valleys and peaks are repeatedly formed in a cross-section perpendicular to the longitudinal direction of the optical cable.

[0016] Here, in a cross-section perpendicular to the longitudinal direction of the optical cable, the cable jacket may have a thickness in an area where the tension member is embedded greater than a thickness in an area where the tension member is not embedded.

[0017] In this case, the steel portion of the cable jacket may be placed at a position radially corresponding to the area where the tensile member is embedded in a cross-section perpendicular to the longitudinal direction of the optical cable.

[0018] And, in a cross-section perpendicular to the longitudinal direction of the optical cable, the minimum thickness of the cable jacket at the main portion may be 1.6 millimeters (mm) or more.

[0019] Additionally, the minimum thickness of the iron portion of the cable jacket in a cross-section perpendicular to the longitudinal direction of the optical cable may be 2.0 millimeters (mm) or more.

[0020] Here, the ratio of the thickness of the cable jacket at the ferrous portion to the thickness of the cable jacket at the ridge portion in a cross-section perpendicular to the longitudinal direction of the optical cable may be 1.02 to 1.25.

[0021] Furthermore, the number of optical units may be 1 to 14, and the number of optical fibers accommodated in one optical unit may be 20 to 150.

[0022] In this case, the binding member of the optical unit may be made of a low-smoke, zero-halogen (LSZH) material.

[0023] In addition, the binding member of the optical unit may be made of aramid, nylon, polyester, or a composite material including one or more of the above materials.

[0024] In addition, the binding member of the optical unit may have a variable shape in a cross-section perpendicular to the longitudinal direction of the optical cable to correspond to the shape of the space arranged inside the cable jacket.

[0025] Here, at least one waterproof yarn may be provided in the interior of the optical unit or in the empty space between the optical units in a cross-section perpendicular to the longitudinal direction of the optical cable.

[0026] Furthermore, the plurality of tensile members may be arranged at equal intervals in the circumferential direction in a cross-section perpendicular to the longitudinal direction of the optical cable.

[0027] Additionally, in a cross-section perpendicular to the longitudinal direction of the optical cable, a pair of the plurality of tension members may be provided at positions facing each other.

[0028] In addition, the plurality of tensile members may be made of aramid reinforced plastic (ARP) material.

[0029] In this case, an auxiliary binder may be provided to wrap and bind the outer sides of the plurality of optical units.

[0030] Additionally, at least one ripcord may be provided on the inside of the cable jacket.

[0031] Additionally, the cable jacket may be made of high-density polyethylene (HDPE) material.

[0032] Furthermore, the optical fiber density, which is the total number of optical fibers accommodated in the cable jacket compared to the internal cross-sectional area of ​​the inner surface of the cable jacket in a cross-section perpendicular to the longitudinal direction of the optical cable, is 9 cores / mm. 2 50 cores / mm 2 It could be.

[0033] In addition, the optical fiber density, which is the total number of optical fibers accommodated in the cable jacket compared to the internal cross-sectional area of ​​the inner surface of the cable jacket in the cross-section perpendicular to the longitudinal direction of the optical cable, is 10 cores / mm. 2 36 cores / mm 2 It could be.

[0034] In this case, the ratio of the internal cross-sectional area of ​​the inner surface of the cable jacket to the cross-sectional area of ​​an imaginary circle with the minimum diameter at any point on the inner surface of the cable jacket in a cross-section perpendicular to the longitudinal direction of the optical cable may be 1.03 to 1.10.

[0035] Here, the ratio of the cross-sectional area of ​​an imaginary circle with the maximum diameter based on any point on the inner surface of the cable jacket to the internal cross-sectional area of ​​the inner surface of the cable jacket in a cross-section perpendicular to the longitudinal direction of the optical cable may be 1.03 to 1.50.

[0036] According to the optical cable according to the present invention, the inner circumferential surface of the cable jacket is configured to be non-circular, thereby reducing the thickness of the cable jacket in an area other than a tensile member area embedded in the longitudinal direction of the cable jacket, thereby ensuring sufficient flexibility of the optical cable, while increasing the empty space inside the cable jacket, thereby reducing interference between optical fiber ribbons accommodated inside the cable jacket and between the inside of the cable jacket and the optical fiber ribbons accommodated inside the cable jacket, thereby minimizing room temperature optical loss of the optical fiber due to external stress.

[0037] In addition, according to the optical cable according to the present invention, by embedding a plurality of tensile members, such as aramid reinforced plastic (ARP) material, in the longitudinal direction of the cable inside the cable jacket, longitudinal shrinkage of the cable jacket can be prevented and the tensile strength of the optical cable can be sufficiently secured.

[0038] In addition, according to the optical cable of the present invention, since multiple rollable optical fiber ribbons are accommodated within the optical unit, multi-core optical fibers are provided within the optical cable per unit area, thereby enabling construction of a large-capacity optical communication network.

[0039] Figure 1 illustrates a state in which an optical cable according to the present invention is pneumatically laid in a duct.

[0040] Figure 2 illustrates a cross-sectional view of one embodiment of an optical cable according to the present invention.

[0041] Figure 3 illustrates a cross-sectional view of another embodiment of an optical cable according to the present invention.

[0042] FIG. 4 is a cross-sectional view showing the angles of the ribs and the ferrule formed on the inner surface of the cable jacket in the optical cable illustrated in FIG. 2.

[0043] Figure 5 illustrates a cross-sectional view of another embodiment of an optical cable according to the present invention.

[0044] Figure 6 illustrates a cross-sectional view of another embodiment of an optical cable according to the present invention.

[0045] Figure 7 illustrates a cross-sectional view of another embodiment of an optical cable according to the present invention.

[0046] Figure 8 illustrates a test facility used for a pneumatic installation test of an optical cable according to the present invention.

[0047] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings. However, the present invention is not limited to the embodiments described herein and may be embodied in other forms. Rather, the embodiments introduced herein are provided to ensure that the disclosure is thorough and complete, and to sufficiently convey the spirit of the invention to those skilled in the art. Like reference numbers designate like elements throughout the specification.

[0048] Figure 1 illustrates a state in which an optical cable according to the present invention is pneumatically laid in a duct.

[0049] As illustrated in FIG. 1, a circular receiving space is formed lengthwise inside a concrete pipe (W), a duct (d) is installed in the receiving space, and a plurality of micro ducts (md) are provided in a bundle shape inside the duct (d), and the optical cable (100) according to the present invention can be installed inside the duct (d) or the micro duct (md) by means of pneumatic installation or traction installation.

[0050] The above duct (d) and micro duct (md) can play a role in protecting the optical cable (100) of the present invention during the installation process or in the installation state.

[0051] Meanwhile, in order to use the limited pipe (W) space more efficiently, the frequency of using micro ducts (md) as well as ducts (d) is increasing, and the inner diameter (D) of micro ducts (md) is increasing. md ) is trending towards further miniaturization.

[0052] As shown in Fig. 1, when the optical cable (100) of the present invention is laid in a micro duct (md), the outer diameter (D) of each optical cable (100) provided in the micro duct (md) c ) is the inner diameter (D) of the micro duct (md) md ) less than, preferably the inner diameter (D) of the micro duct (md) md) should be composed of approximately 80% or less to enable stable long-distance pneumatic laying.

[0053] Meanwhile, when the optical cable (100) of the present invention is made thinner to enable pneumatic installation within a micro duct (md), the internal space of the optical cable (100) is reduced, and stress is applied to the optical fiber (11) accommodated within the optical cable (100) during the installation process of the optical cable (100), which may cause loss of an optical signal.

[0054] Therefore, in order to pneumatically install the optical cable (100) of the present invention in a micro duct (md), the optical cable (100) must be thinned and maintain optical transmission characteristics, and furthermore, the flexibility of the optical cable (100) must be secured and sufficient tensile strength must be secured to enable traction installation.

[0055] Hereinafter, with reference to FIG. 2 and below, the structure of the optical cable (100) according to the present invention will be examined in detail.

[0056] Figures 2 to 7 illustrate cross-sectional views of various embodiments of an optical cable according to the present invention.

[0057] As illustrated in FIGS. 2 to 7, an optical cable (100) according to the present invention comprises: at least one optical unit (10) comprising a plurality of optical fibers (11), a plurality of rollable optical fiber ribbons (11R) capable of being rolled in the width direction, and a binding member (12) binding the plurality of rollable optical fiber ribbons (11R); a cable jacket (30) wrapping the at least one optical unit (10); and four or more tensile members (20) embedded in the cable jacket (30) in the longitudinal direction of the cable and spaced apart from each other in the circumferential direction of the cable jacket (30); wherein the inner circumferential surface of the cable jacket (30) may have a non-circular cross-section in a cross-section perpendicular to the longitudinal direction of the cable jacket (30).

[0058] The optical unit (10) constituting the optical cable (100) according to the present invention may be configured to include a plurality of optical fibers (11) or a plurality of rollable optical fiber ribbons (11R) and one or more binding members (12) wrapping them.

[0059] The rollable optical fiber ribbon (11R) constituting the above optical unit (10) may be an optical fiber ribbon (11R) that is capable of being rolled in the width direction by joining a plurality of optical fibers (11) arranged in a longitudinally parallel manner.

[0060] Here, among the plurality of optical fibers (11), the rollable optical fiber ribbon (11R) can be mutually bonded to a pair of adjacent optical fibers (11) through a bonding area formed by intermittently applying a bonding resin along the longitudinal direction of the optical fiber (11).

[0061] That is, since the rollable optical fiber ribbon (11R) can roll in the width direction in the non-bonded area where the bonding resin is not applied, the rollable ribbon can be efficiently accommodated in the internal space of the optical cable (100).

[0062] In this way, the optical cable (100) according to the present invention can increase the number of cores of optical fibers (11) accommodated in the optical cable (100) of the same area by having a rollable optical fiber ribbon (11R) that can be flexibly changed by rolling or folding the optical fiber ribbon in the width direction.

[0063] Each optical fiber (11) constituting the above-mentioned rollable optical fiber ribbon (11R) may be a fine-diameter optical fiber (11) having a diameter of 200 ㎛ or less that can be intermittently bonded while being spaced apart from an adjacent optical fiber, or a general optical fiber (11) having a diameter of 240 ㎛ to 260 ㎛ that can be intermittently bonded while being in contact with an adjacent optical fiber without being spaced apart from an adjacent optical fiber.

[0064] In the embodiments illustrated in FIGS. 2 to 7, the optical cable (100) according to the present invention is illustrated as having a total of 144 optical fibers (11) accommodated within a plurality of optical units (10), and the 144 optical fibers (11) having 12 rollable optical fiber ribbons (11R) capable of being rolled in the width direction, each composed of 12 optical fibers (11). However, the number of optical units (10), the number of rollable optical fiber ribbons (11R) provided in one optical unit (10), and the number of optical fibers (11) constituting one rollable optical fiber ribbon (11R) may be increased or decreased depending on the transmission characteristics or capacity required for the optical cable (100).

[0065] Preferably, the number of optical units (10) is 1 to 14, and the number of optical fibers (11) accommodated in one optical unit (10) can be configured in the range of 20 to 150.

[0066] In the case of the embodiments illustrated in FIGS. 2 to 4, the optical cable (100) according to the present invention has two optical units (10) inside the cable jacket (30), and one optical unit (10) can accommodate six rollable optical fiber ribbons (11R) composed of twelve optical fibers (11), thereby providing a total of 144 optical fibers (11). In the case of the embodiment illustrated in FIG. 4, the optical cable (100) has four optical units (10), and one optical unit (10) can accommodate three rollable optical fiber ribbons (11R) composed of twelve optical fibers (11), thereby providing a total of 144 optical fibers (11). However, the number of rollable optical fiber ribbons or optical fibers constituting one optical cable or optical unit can be increased or decreased.

[0067] The binding member (12) constituting the optical unit (10) is a component for binding the optical fiber (11) or the rollable optical fiber ribbon (11R), and may preferably be formed in the form of a tube, binder thread, binder tape, wire, etc. that is continuous without any breaks in the circumferential direction.

[0068] The material of the above binding member (12) may be a polyolefin resin material that is heat-resistant, lightweight, and provides transparency as needed, and preferably, may be made of a low smoke zero halogen (LSZH) material that is flame-retardant and environmentally friendly. In addition, in order to secure sufficient tensile strength, flexibility, and durability, aramid, nylon, polyester, or a composite material containing one or more of the above materials may be used.

[0069] In addition, the binding member (12) may be maintained in a circular or oval shape while the rollable optical fiber ribbon (11R) is accommodated therein, but may be made of a material having a thin thickness, relatively low hardness, low elastic modulus, or flexibility, and may be made of a material whose shape changes in response to the shape of the space arranged within the cable jacket (30).

[0070] In this way, the optical unit (10) is provided with a binding member (12) of this structure, so that even when the optical cable (100) is bent, compressed, or subjected to external impact, the binding member (12) is not broken and its shape changes, thereby minimizing optical loss or deterioration of optical characteristics.

[0071] At least one waterproof yarn (13) may be provided in the internal space of the binding member (12) constituting the above-mentioned optical unit (10) or in the empty space between different optical units (10) to provide waterproof performance. In addition, in order to enhance waterproof performance, a waterproofing material such as waterproof powder or waterproof jelly may be further provided in addition to the waterproof yarn (13).

[0072] The above cable jacket (30) may be provided to completely surround the circumference of a plurality of the above optical units (10), and may have a non-circular cross-section on the inner surface. A detailed description of the shape of the above cable jacket (30) will be described later.

[0073] The above cable jacket (30) may be made of a polyethylene resin such as high density polyethylene (HDPE) or medium density polyethylene (MDPE), and preferably, the cable jacket (30) may be made of a high density polyethylene material having excellent mechanical strength.

[0074] Four or more tensile members (20) may be embedded in the cable jacket (30) along the length of the cable. The plurality of tensile members (20) may distribute the tensile force, torsion, compressive force, or moment applied during the bobbin winding or laying process of the optical cable (100) to each tensile member (20), thereby preventing damage to the internal optical unit (10) and the optical fiber (11) constituting the same.

[0075] In general, the tensile member (20) used in the optical cable (100) may be composed of a plastic material such as fiberglass reinforced plastic (FRP) or a metal material such as steel wire or stranded wire, and the tensile member (20) of the optical cable (100) according to the present invention may preferably be composed of an aramid reinforced plastic (ARP) material.

[0076] In this way, when the tensile member (20) is composed of an aramid reinforced plastic (ARP) material, the tensile strength of the optical cable (100) is strengthened, shrinkage of the cable jacket (30) made of polyethylene is reduced, and flexibility of the optical cable (100) is secured, thereby improving the laying performance during pneumatic laying.

[0077] The above tensile member (20) may have a circular cross-section and may have a diameter of 0.4 millimeters (mm) to 1.2 millimeters (mm).

[0078] In addition, the plurality of tension members (20) may be provided spaced apart from each other in the circumferential direction of the cable jacket (30).

[0079] Preferably, the plurality of tension members (20) are arranged at equal intervals from each other, and a pair of tension members (20) are arranged at positions facing each other at the center of the optical cable (100), so that a longitudinal tensile force can be uniformly provided in the circumferential direction of the cable jacket (30) by the plurality of tension members (20), and longitudinal shrinkage of the cable jacket (30) can be uniformly suppressed in the entire circumferential region of the cable jacket (30).

[0080] As described above, the optical cable (100) according to the present invention is characterized in that the inner circumferential surface of the cable jacket (30) has a non-circular cross-section based on a cross-section cut in a direction perpendicular to the longitudinal direction of the cable jacket (30).

[0081] As illustrated in FIGS. 2 to 7, the inner circumferential surface of the cable jacket (30) may be configured with a fluting structure in which grooves and protrusions are repeatedly formed along the circumferential direction. That is, based on the cross-section of the optical cable (100), the inner circumferential surface area of ​​the cable jacket (30) may have a shape other than a circular cross-section. In the case of a non-circular cross-section, the inner circumferential surface of the cable jacket may be configured with a shape other than a fluting structure in which grooves and protrusions are repeatedly formed, for example, various structures in which the thickness of the cable jacket is variable.

[0082] In addition, in a cross-section perpendicular to the longitudinal direction of the cable jacket (30), the concave portion and the protruding portion of the inner surface (30i) of the cable jacket (30) may have a curved shape without a discontinuity. Preferably, the inner surface of the cable jacket (30) may have a shape in which the concave portion and the protruding portion are continuously connected in a curved shape without a sharp part or a discontinuity. If the concave portion and the protruding portion are not connected in a curved shape as in FIG. 3, there is a risk that interference may occur between the inner surface of the cable jacket and the optical unit, resulting in damage to the optical unit.

[0083] In this way, since the inner circumferential surface (30i) of the cable jacket (30) is configured in a non-circular shape, the internal empty space of the cable jacket (30) can be increased compared to the case where the inner circumferential surface (30i) of the cable jacket (30) is configured in a circular cross-section. As illustrated in FIGS. 2 to 7, the shape of the binding member (12) of the optical unit (10) accommodated in the cable jacket (30) can be varied in response to the shape of the internal space of the cable jacket (30), and thus the internal empty space of the binding member (12) of the optical unit (10) accommodated in the cable jacket (30) can also be expanded.

[0084] And, as shown in Fig. 4, the ratio (R) of the angle (θ2) forming the iron portion on the inner surface (30i) of the cable jacket (30) from the center (C) of the optical cable (100) in the cross section perpendicular to the longitudinal direction of the cable jacket (30) to the angle (θ1) forming the yoke A ) can range from 1.10 to 2.00.

[0085] That is, the angle (θ2) forming each section on the inner surface (30i) of the cable jacket (30) is formed to be in the range of 1.10 to 2.00 times the angle (θ1) forming each yoke, thereby reducing the thickness of the cable jacket (30) in the area corresponding to the yoke on the inner surface (30i) of the cable jacket (30), thereby sufficiently securing an empty space inside the inner surface (30i) of the cable jacket (30) while stably maintaining the structure of the optical cable (100) from external impact.

[0086] Here, the main and the steel portion of the cable jacket (30) are set to a virtual circle (M) having a middle value between the outer diameter of the inscribed circle (I) of the inner surface (30i) of the cable jacket (30) and the outer diameter of the circumscribed circle (O) of the inner surface (30i), and can be distinguished based on the section where the virtual circle (M) intersects the inner surface (30i) of the cable jacket (30).

[0087] Accordingly, the optical fiber density (ρ), which is the total number of optical fibers (11) accommodated in the cable jacket (30) compared to the internal cross-sectional area of ​​the inner surface (30i) of the cable jacket (30), f ) can be sufficiently reduced to minimize room temperature optical loss due to stress applied to the optical fiber (11) when friction occurs between the optical cable (100) and the optical fiber (11) or the binding member (12) or cable jacket (30) during the installation process of the optical cable (100).

[0088] Here, the optical fiber density (ρ f ) can be expressed as the number of optical fiber (11) cores per unit area, and the optical fiber density (ρ) for minimizing room temperature light loss f ) is the unit area (1mm 2 ) can be 9 to 50 cores per unit area (1 mm 2 ) can be from 10 to 36 or more.

[0089] That is, the inner surface (30i) of the cable jacket (30) is configured in a non-circular shape so that the optical fiber density (ρ) of the optical unit (10) is increased without increasing the outer diameter of the optical cable (100). f ) can be reduced to minimize the problem of optical characteristic deterioration at room temperature, and the flexibility of the optical cable (100) can be effectively improved.

[0090] Compared to the case where the inner surface (30i) of the cable jacket (30) is configured as a circular cross-section, when the inner surface (30i) of the cable jacket (30) is configured as a non-circular shape, the thickness and weight of the cable jacket (30) can be reduced by an area corresponding to the main portion of the inner surface (30i) structure of the cable jacket (30), thereby improving the flexibility of the optical cable (100).

[0091] In addition, the cable jacket (30) may not have a constant thickness in the circumferential direction, and preferably, the cable jacket (30) may have a shape in which the thickness increases and decreases repeatedly in the circumferential direction.

[0092] Here, the cable jacket (30) may be configured such that the thickness in the area where the tension member (20) is embedded is greater than the thickness in the area where the tension member (20) is not embedded. That is, by adjusting and optimizing the circumferential thickness of the cable jacket (30) in consideration of the area where the tension member (20) is embedded inside the cable jacket (30), the weight of the cable jacket (30) can be effectively reduced, thereby improving the flexibility of the optical cable (100).

[0093] As an example, the optical cable (100) according to the present invention may be configured such that the inner circumference (30i) of the cable jacket (30) is non-circular as shown in FIGS. 2 to 5, but the outer circumference of the cable jacket (30) has a circular cross-section like the cable jacket (30) structure of a general optical cable (100).

[0094] Meanwhile, as shown in FIGS. 2 to 5, when the inner surface (30i) of the cable jacket (30) is non-circular and the outer surface of the cable jacket (30) is circular, the inner surface (30i) of the cable jacket (30) may have a concave portion and a convex portion alternately arranged, and the convex portion of the inner surface (30i) of the cable jacket (30) may be arranged at a position radially corresponding to the area where each tension member (20) is embedded inside the cable jacket (30).

[0095] In addition, as another embodiment, the optical cable (100) according to the present invention may be configured such that the inner circumference (30i) of the cable jacket (30) is non-circular as shown in FIGS. 6 and 7, but the outer circumference of the cable jacket (30) is also non-circular.

[0096] As illustrated in FIG. 6, both the inner surface (30i) and the outer surface of the cable jacket (30) may have a fluting structure in which a ridge and a rib are repeatedly formed in the circumferential direction of the inner surface (30i) of the cable jacket (30), and the outer surface of the cable jacket (30) and the inner surface (30i) of the cable jacket (30) may have shapes that correspond to each other in the direction in which they face each other.

[0097] In this way, if both the inner surface (30i) and the outer surface of the cable jacket (30) are configured with a non-circular cross-section, for example, a fluting structure, the overall weight and thickness of the cable jacket (30) can be reduced compared to a case where only the inner surface (30i) of the cable jacket (30) is configured with a non-circular shape.

[0098] That is, as in the description referring to FIGS. 2 to 5, the cable jacket (30) can be removed from the outer surface of the cable jacket (30) in an area corresponding to the main portion of the fluting structure, so that the overall weight and thickness of the cable jacket (30) can be reduced, thereby further improving the flexibility of the optical cable (100).

[0099] In addition, when the inner surface (30i) and outer surface of the cable jacket (30) are configured in a non-circular shape, the friction area between the outer surface of the cable jacket (30) and the inner surface of the duct (d) or micro duct (md) in which the optical cable (100) is laid can be reduced, thereby effectively preventing damage and cracks of the cable jacket (30).

[0100] In addition, as shown in Fig. 7, both the inner and outer surfaces of the cable jacket (30) are configured as non-circular, but the outer surface of the cable jacket (30) may have a structure in which a plurality of protrusions (33) are formed.

[0101] A plurality of protrusions (33) may be formed separately on the outer surface of the cable jacket (30) to have different materials. In addition, the plurality of protrusions (33) may be formed of the same polyethylene resin as the cable jacket (30) by being extruded integrally with the cable jacket (30).

[0102] Here, a plurality of protrusions (33) formed on the outer surface of the cable jacket (30) can be continuously formed in the longitudinal direction of the optical cable (100), and each protrusion (33) is not limited to a triangular cross-sectional shape, and can be formed of protrusions of various shapes as long as it has a shape that can reduce the friction area between the inner surface of the duct (d) or micro duct (md) in which the optical cable (100) is laid, such as a shape in which fine-sized valleys and peaks are repeated, unlike the inner surface of the cable jacket.

[0103] The above-described plurality of protrusions can further reduce the contact area between the outer surface of the cable jacket (30) and the inner surface of the duct (d) or micro duct (md) in which the optical cable (100) is laid, similar to the embodiment illustrated in FIG. 7, thereby minimizing damage to the cable jacket (30) due to frictional force.

[0104] The cable jacket (30) above can have various exemplary structures within a range in which the inner circumferential surface (30i) of the cable jacket (30) is formed into a non-circular cross-sectional structure as illustrated in FIGS. 2 to 7, and the cable jacket (30) can be configured to have a minimum thickness of 1.6 millimeters (mm) or more in the circumferential direction at a key portion thereof.

[0105] When the minimum thickness of the above cable jacket (30) at the main portion is less than 1.6 millimeters (mm), it is advantageous in terms of flexibility of the optical cable (100), but the tensile strength and tensile strength of the optical cable (100) are reduced, so that the cable jacket (30) is easily worn or damaged by external friction, and the rollable optical fiber ribbon (11R) inside the cable jacket (30) and the optical fiber (11) constituting it cannot be sufficiently protected.

[0106] And, the minimum thickness in the circumferential direction of the iron portion of the cable jacket (30) may be configured to be 2.0 millimeters (mm) or more so as to sufficiently protect the optical fiber (11) while embedding the tensile member (20).

[0107] If the minimum thickness of the iron portion of the cable jacket (30) is less than 2.0 millimeters (mm), the optical cable (100) cannot secure sufficient tensile strength and tensile strength, and the shrinkage reduction effect of the cable jacket (30) by the tensile member (20) cannot be secured.

[0108] In addition, the ratio (R) of the thickness at the iron part of the cable jacket (30) to the thickness at the ridge part of the cable jacket (30) B ) can be composed of 1.02 to 1.25.

[0109] The ratio of the thickness at the iron portion of the above cable jacket (30) to the thickness at the ridge portion of the above cable jacket (30) (R B) is less than 1.02, the effect of increasing the cross-sectional area of ​​the inner surface (30i) of the cable jacket (30) is minimal, so it may be difficult to thin the optical cable (100) while satisfying excellent optical fiber loss characteristics, and the ratio (R B ) is greater than 1.25, the external force is concentrated on the main part of the cable jacket (30), which may cause the structural stability of the optical cable (100) to be lacking and the bending characteristics to deteriorate.

[0110] In addition, the ratio (R) of the internal cross-sectional area of ​​the inner surface (30i) of the cable jacket (30) to the cross-sectional area of ​​the inscribed circle (I) of the inner surface (30i) C ) may be 1.03 to 1.10. Here, the inscribed circle (I) means an imaginary circle having the minimum diameter based on an arbitrary point passing through the inner circumferential surface (30i) of the cable jacket (30).

[0111] The ratio (R) of the internal cross-sectional area of ​​the inner circumference (30i) of the above cable jacket (30) to the cross-sectional area of ​​the above inscribed circle (I) C ) is less than 1.03, the empty space is not formed sufficiently wide around the inner surface (30i) of the cable jacket (30) compared to the case where the inner surface (30i) of the cable jacket is circular, so interference between optical fiber ribbons (11R) inside the optical unit (10) or interference between the inner surface of the cable jacket (30) and the optical fiber ribbon (11R) cannot be sufficiently prevented.

[0112] On the other hand, the ratio (R) of the internal cross-sectional area of ​​the inner circumference (30i) of the cable jacket (30) to the cross-sectional area of ​​the inscribed circle (I) C ) is greater than 1.10, the ratio of the yoke in the cable jacket (30) becomes excessively high, and the overall function of the cable jacket (30) to protect the optical unit (10) accommodated inside the optical cable (100) may be deteriorated.

[0113] In addition, the ratio (R) of the cross-sectional area of ​​the circumscribed circle (O) of the inner surface (30i) of the cable jacket (30) to the internal cross-sectional area of ​​the inner surface (30i) of the cable jacket (30)D ) is preferably in the range of 1.03 to 1.50. Here, the circumscribed circle (O) means an imaginary circle having the maximum diameter based on an arbitrary point passing through the inner circumferential surface (30i) of the cable jacket (30).

[0114] The ratio (R) of the cross-sectional area of ​​the circumscribed circle (O) of the inner surface (30i) of the cable jacket (30) to the internal cross-sectional area of ​​the inner surface (30i) of the cable jacket (30) D ) is less than 1.03, the effect of increasing the cross-sectional area of ​​the inner surface (30i) of the cable jacket (30) due to the formation of the yoke of the cable jacket (30) may be minimal, and the ratio (R D ) is greater than 1.50, structural stability may deteriorate.

[0115]

[0116] [Example]

[0117]

[0118] In the experimental example below, a pneumatic installation test was performed on an optical cable (100) according to the present invention.

[0119] The above pneumatic installation test used a track including multiple macro-bending and micro-bending sections as shown in Fig. 8(a), and installed a microduct (230) having an inner diameter of 3 mm and an outer diameter of 6 mm in the section implemented as shown in Fig. 8(b), and performed pneumatic transmission using a pneumatic installation device Minijet P400 from Plumettaz inside the microduct (230). At this time, a pneumatic transmission characteristic evaluation was performed to evaluate whether the length of the pneumatically transmitted optical cable (100) was 1 km or longer, a signal transmission characteristic evaluation was performed to evaluate whether the loss value satisfied 0.35 dB / km or less by measuring the optical signal loss at a wavelength of 1550 nm at room temperature (23°C) for the pneumatically transmitted sample, and a cable appearance evaluation was performed to evaluate whether deformation such as pressing, bending, or kinking occurred by visually checking the appearance of the pneumatically transmitted sample.

[0120] The sample to be evaluated is a 144-core optical cable (100) in which two optical units (10) each containing six rollable optical fiber ribbons (11R) composed of 12 optical fibers (11) having an outer diameter of 250 μm are wrapped with a binding member (12) and accommodated within a cable jacket (30), as illustrated in Fig. 2. In the optical cable (100), eight tensile members (20) are built into the cable jacket (30) at equal intervals, and a recess is formed on the inner surface of the cable jacket (30) between each adjacent pair of tensile members (20), and a ferrule is formed identically on the inner surface of the cable jacket (30) at a position corresponding to each tensile member (20). In addition, when extruding the cable jacket (30), different dies were applied to 10 samples to form different structures and shapes of the main and iron parts of each sample, and it was confirmed whether each sample satisfied the performance required for pneumatic transmission characteristics, signal transmission characteristics, and cable appearance evaluation.

[0121] Sample 12345678910 Cable jacket reinforcing angle to ridge forming angle ratio (RA) 1.55 2.15 1.77 1.53 2.40 2.05 1.83 0.94 1.55 1.55 Cable jacket reinforcing thickness to ridge thickness ratio (RB) 1.15 1.26 1.03 0.87 1.24 1.14 1.10 1.13 0.82 1.21 Cable jacket inner circumference internal cross-sectional area to inner circumference inscribed circle cross-sectional area (RC) 0.83 1.09 1.03 0.85 0.93 1.22 1.09 1.06 0.89 1.04 Cable jacket inner circumference external cross-sectional area to inner circumference internal cross-sectional area (RD)1.341.441.741.381.421.361.201.151.010.94Pneumatic transmission OXXXOOOOXOSignal transmission XOOOOXOOXXCable appearance OXXOXXOXXO

[0122]

[0123] Referring to Table 1 above, Sample 1 has a ratio of the inner cross-sectional area of ​​the cable jacket to the inscribed circle cross-sectional area of ​​the inner circumference (R C) was low, the internal accommodation space of the cable jacket (30) became smaller, and as a result, some optical fibers (11) were damaged during the pneumatic laying process, which deteriorated the signal transmission characteristics, and sample 2 had a ratio of the cable jacket steel part thickness to the cable jacket core thickness (R B ) was high, the structure of the optical cable (100) could not be stably maintained from external impact, and the appearance of the optical cable (100) was partially deformed, failing to satisfy the pneumatic laying characteristics.

[0124] Additionally, sample 3 shows the ratio of the outer circumferential cross-sectional area of ​​the cable jacket to the inner circumferential cross-sectional area of ​​the inner circumferential area (R D ) is high, the fiber protection performance is deteriorated and the appearance of the optical cable (100) is deformed as the cable jacket (30) thickening area is widened, and sample 4 has a ratio of cable jacket steel thickness to thickening area (R B ) was low, so the resistance to external impact during pneumatic laying was weak, and the bending characteristics were insufficient, so the pneumatic laying characteristics were not satisfied.

[0125] Additionally, sample 5 showed a ratio of cable jacket yoke forming angle to steel yoke forming angle (R A ) was high, so that the structure of the optical cable (100) could not be stably maintained from external impact, and it was confirmed that the exterior of the optical cable (100) was partially pressed, and sample 6 was the ratio of the internal cross-sectional area of ​​the inner circumference of the cable jacket to the cross-sectional area of ​​the inner circumference of the inscribed circle (R C ) was high, the internal protection function was weakened by the widely formed ridge of the cable jacket (30), stress was applied to some optical fibers (11), signal transmission characteristics were deteriorated, and the exterior of the optical cable (100) was partially pressed.

[0126] In addition, sample 7 was formed and arranged in an appropriate ratio between all the main parts and the ferrules of the cable jacket (30) of the optical cable (100) of the present invention, satisfying all of the pneumatic transmission characteristics, signal transmission characteristics, and cable appearance evaluations. On the other hand, sample 8 had a ratio of the cable jacket main part formation angle to the ferrule formation angle (R A) It was confirmed that the external impact was concentrated on the lower part of the narrow cable jacket (30), causing some damage to the exterior of the optical cable (100).

[0127] In addition, sample 9 was manufactured without the appropriate ratio and arrangement between the main part and the steel part of the cable jacket (30) of the optical cable (100) of the present invention, and thus did not satisfy the pneumatic transmission characteristics, signal transmission characteristics, and cable appearance evaluations, and sample 10 had a ratio of the outer circumferential cross-sectional area of ​​the inner circumference of the cable jacket to the inner circumferential cross-sectional area of ​​the inner circumference (R D ) was low, so the internal accommodation space of the cable jacket (30) was small, and it was confirmed that the signal transmission characteristics of some optical fibers (11) were deteriorated due to mutual pressure between optical fibers during the pneumatic laying process.

[0128] An auxiliary binder (40) for wrapping and binding the outer sides of the plurality of optical units (10) may be provided on the inside of the cable jacket (30) having such a structure. The auxiliary binder (40) may be formed by, for example, winding a binding tape or binding yarn made of polyethylene terephthalate (PET) material horizontally around the outer sides of the plurality of optical units (10) in a predetermined pitch range.

[0129] Here, the auxiliary binder (40) may be provided by binding the optical unit before extrusion of the cable jacket (30). The auxiliary binder (40) prevents the binding state of the optical unit (10) from being released during the extrusion process of the cable jacket (30).

[0130] In addition, at least one ripcord (50) may be provided inside the cable jacket (30) to facilitate stripping of the cable jacket (30). The ripcord (50) may be made of a polymer resin such as polyester or an aramid fiber. Preferably, a pair of ripcords (50) may be provided inside the cable jacket (30), and each ripcord (50) may be positioned facing each other at the center of the cable.

[0131] While this specification has described preferred embodiments of the present invention, those skilled in the art will appreciate that various modifications and variations can be made to the present invention without departing from the spirit and scope of the invention as defined in the claims below. Therefore, any modified implementation that fundamentally includes the elements of the claims should be considered within the technical scope of the present invention.

Claims

1. One or more optical units comprising a plurality of optical fibers and a tube-shaped binding member for accommodating the plurality of optical fibers; A cable jacket surrounding one or more of the optical units; and It includes four or more tensile members embedded in the length direction of the cable inside the cable jacket and spaced apart from each other in the circumferential direction of the cable jacket; An optical cable characterized in that the inner surface of the cable jacket has a fluting structure in which a concave portion and a convex portion are repeatedly formed along the circumference in a cross-section perpendicular to the longitudinal direction of the cable jacket.

2. In paragraph 1, An optical cable characterized in that the plurality of optical fibers are in the shape of a plurality of rollable optical fiber ribbons capable of being rolled in the width direction.

3. In paragraph 1, An optical cable characterized in that the inner circumferential surface and the steel portion of the cable jacket are connected in a curved shape in a cross-section perpendicular to the longitudinal direction of the optical cable.

4. In paragraph 1, An optical cable characterized in that the ratio of the angle forming the inner surface of the cable from the center of the cable to the angle forming the yoke in a cross-section perpendicular to the longitudinal direction of the cable jacket is 1.10 to 2.

00.

5. In paragraph 1, An optical cable characterized in that the outer surface of the cable jacket has a circular cross-section in a cross-section perpendicular to the longitudinal direction of the optical cable.

6. In paragraph 1, An optical cable characterized in that the outer surface of the cable jacket has a structure in which valleys and peaks are repeatedly formed in a cross-section perpendicular to the longitudinal direction of the optical cable.

7. In paragraph 1, An optical cable characterized in that, in a cross-section perpendicular to the longitudinal direction of the optical cable, the cable jacket has a thickness in an area where the tension member is embedded that is greater than a thickness in an area where the tension member is not embedded.

8. In paragraph 1, An optical cable characterized in that, in a cross-section perpendicular to the longitudinal direction of the optical cable, the steel portion of the cable jacket is positioned at a position radially corresponding to the area in which the tensile member is embedded.

9. In paragraph 1, An optical cable characterized in that the minimum thickness of the cable jacket at the main portion in a cross-section perpendicular to the longitudinal direction of the optical cable is 1.6 millimeters (mm) or more.

10. In paragraph 1, An optical cable characterized in that the minimum thickness of the iron portion of the cable jacket in a cross-section perpendicular to the longitudinal direction of the optical cable is 2.0 millimeters (mm) or more.

11. In paragraph 1, An optical cable characterized in that the ratio of the thickness of the cable jacket at the ferrous portion to the thickness of the cable jacket at the ridge portion in a cross-section perpendicular to the longitudinal direction of the optical cable is 1.02 to 1.

25.

12. In paragraph 1, An optical cable characterized in that the number of optical units is 1 to 14, and the number of optical fibers accommodated in one optical unit is 20 to 150.

13. In paragraph 1, An optical cable characterized in that the binding member of the above optical unit is made of a low-smoke, zero-halogen (LSZH) material.

14. In paragraph 1, An optical cable characterized in that the binding member of the optical unit is made of aramid, nylon, polyester, or a composite material containing one or more of the above materials.

15. In paragraph 1, An optical cable characterized in that the binding member of the optical unit in a cross-section perpendicular to the longitudinal direction of the optical cable can have a variable shape corresponding to the shape of the space arranged inside the cable jacket.

16. In paragraph 1, An optical cable characterized in that at least one waterproof yarn is provided in a cross-section perpendicular to the longitudinal direction of the optical cable or in a space inside the optical unit or between the optical units.

17. In paragraph 1, An optical cable characterized in that the plurality of tensile members are arranged at equal intervals in the circumferential direction in a cross-section perpendicular to the longitudinal direction of the optical cable.

18. In paragraph 1, An optical cable characterized in that the plurality of tension members are provided in pairs facing each other in a cross-section perpendicular to the longitudinal direction of the optical cable.

19. In paragraph 1, An optical cable characterized in that the above plurality of tensile members are made of aramid reinforced plastic (ARP) material.

20. In paragraph 1, An optical cable characterized in that it is provided with an auxiliary binder for wrapping and binding the outer sides of the plurality of optical units.

21. In paragraph 1, An optical cable characterized in that at least one ripcord is provided on the inside of the cable jacket.

22. In paragraph 1, An optical cable characterized in that the above cable jacket is made of high-density polyethylene (HDPE) material.

23. In paragraph 1, The optical fiber density, which is the total number of optical fibers accommodated in the cable jacket compared to the internal cross-sectional area of ​​the inner surface of the cable jacket in the cross-section perpendicular to the longitudinal direction of the optical cable, is 9 cores / mm. 2 50 cores / mm 2 An optical cable characterized by:

24. In paragraph 1, The optical fiber density, which is the total number of optical fibers accommodated in the cable jacket compared to the internal cross-sectional area of ​​the inner surface of the cable jacket in a cross-section perpendicular to the longitudinal direction of the optical cable, is 10 cores / mm. 2 36 cores / mm 2 An optical cable characterized by:

25. In paragraph 1, An optical cable characterized in that the ratio of the internal cross-sectional area of ​​the inner surface of the cable jacket to the cross-sectional area of ​​an imaginary circle with the minimum diameter at any point on the inner surface of the cable jacket in a cross-section perpendicular to the longitudinal direction of the optical cable is 1.03 to 1.

10.

26. In paragraph 1, An optical cable characterized in that the ratio of the cross-sectional area of ​​an imaginary circle having the maximum diameter based on any point on the inner surface of the cable jacket to the internal cross-sectional area of ​​the inner surface of the cable jacket in a cross-section perpendicular to the longitudinal direction of the optical cable is 1.03 to 1.50.

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