Optical cable

Abstract

The present invention relates to an optical cable which can be installed along an overhead line, and to an optical cable which can provide sufficient tensile strength while minimizing the total outer diameter and weight thereof, increase long-term reliability by minimizing jacket shrinkage, and improve stripping workability by enabling waterproofing tape and the like to be removed together with a reinforcing layer during stripping work.

Description

optical cable

[0001] The present invention relates to an optical cable. More specifically, the present invention relates to an optical cable that can be installed on an overhead line, minimizing the overall outer diameter and weight of the optical cable while providing sufficient tensile strength and minimizing jacket shrinkage to enhance long-term reliability while also improving workability during stripping operations.

[0002] Optical cables are a means of transmitting large-capacity signals in various communication networks. With the recent expansion of advanced wired and wireless communication services such as FTTH and 4G and 5G, the demand for optical cables is increasing.

[0003] Optical cables are classified in various ways depending on their structure and usage environment. Among these, optical cables for overhead lines can be installed on structures such as utility poles to provide optical communication networks.

[0004] In order to safely protect the optical fibers branching from the overhead line optical cable to each network terminal device from external influences, a connection box is used. The overhead line optical cable is connected to at least one splitter installed inside the connection box to build a large-capacity optical communication network.

[0005] An optical cable for an overhead line connected to a connection box may generally be configured to include at least one tensile member for reinforcing tensile strength, a plurality of optical units including optical fibers and tube members that are connected to the tensile member, a waterproof tape layer for preventing moisture from penetrating into the cable, a binding tape layer for binding the tube member or waterproof tape layer of the optical unit, and an outer jacket.

[0006] When connecting optical cables for overhead lines to a splice enclosure, the outer jacket must first be stripped using a ripcord to expose the optical unit, and then the binder layer within the outer jacket must be removed. This binder layer is provided to bind the outer surface of the waterproof tape or the tubular member of the optical unit. However, the process of removing the binder layer within the outer jacket is time-consuming and, because a stripping knife must be used to cut the binder layer, there is a risk of damage to the internal optical unit.

[0007] Specifically, in the case of the loose tube type optical cable disclosed in the previously introduced Korean Patent No. KR 10-0910346, when branching or withdrawing the optical unit, the work of removing the waterproof tape (28) after removing the reinforcing tape (29) inside the cable jacket is required, and in particular, there is a problem in that a stripping cutter, etc. is used during the work of removing the waterproof tape (28) inside the reinforcing tape (29), and there is a high risk of damage to the internal optical unit by the cutter, etc. There was a risk of damage to the internal optical unit by the stripping knife.

[0008] In addition, the loose tube type optical cable disclosed in Korean Patent No. KR 10-0511116, etc., has a problem in that a separate assembly (binder, 100a) is applied to assemble the optical unit and the tensile member due to the linear assembly structure, and a separate process is required to remove the binder when branching or pulling out the optical unit from the optical cable, which takes a long time.

[0009] Furthermore, conventional optical cables for overhead lines have insufficient tensile strength and bonding strength between cable components, which can cause the outer jacket of the optical cable to separate inside the connection box, or cause damage or deformation of the tensile members or optical units inside the optical cable.

[0010] Furthermore, conventional optical cables for overhead lines have a large outer diameter and weight, which limits the expansion of overhead lines due to the increased load on utility poles when installed. Therefore, there is a growing demand for optical cables for overhead lines that are thinner and lighter than conventional cables.

[0011] The present invention aims to provide an optical cable that can be installed on an overhead line, which minimizes the overall outer diameter and weight of the optical cable, provides sufficient tensile strength, minimizes jacket shrinkage to increase long-term reliability, and improves stripping workability by allowing waterproof tape and the like to be removed together with the reinforcing layer during stripping work.

[0012] In order to solve the above problem, the present invention can provide an optical cable comprising: a core portion including a tensile member; and a plurality of optical units including a plurality of optical fibers and a tube member for accommodating the plurality of optical fibers; a waterproof member wrapping around the outer side of the core portion; a reinforcing layer wrapping around the outer periphery of the waterproof member and bonded to at least a portion of the waterproof member; and an outer jacket wrapping around the outer periphery of the reinforcing layer.

[0013] Additionally, the outer diameter of the optical cable may be smaller than five times the outer diameter of the tension member.

[0014] And, each of the plurality of optical units may be twisted in the SZ direction with the tension member at a twist pitch of 60 millimeters (mm) to 900 millimeters (mm) while at least a portion thereof is in contact with the outer surface of the tension member.

[0015] Here, the waterproofing member may be a waterproofing tape that is attached to wrap the core portion.

[0016] In this case, the center of the above one tensile member may not be located at the center of the core portion.

[0017] Additionally, a plurality of auxiliary tension members can be embedded in the outer jacket.

[0018] Additionally, the plurality of auxiliary tension members may be arranged symmetrically around the core portion.

[0019] And, the number of the optical units may be two or three.

[0020] Here, the outer diameter of the optical unit may be 2.1 millimeters (mm) or more, and the outer diameter of the tensile member may be 2.2 millimeters (mm) or more.

[0021] In this case, the tube member of the optical unit includes polybutylene terephthalate (PBT) or polypropylene (PP) as a base resin, and the Young's modulus may be 1000 MPa to 3000 MPa.

[0022] And, the tensile member is composed of a reinforced plastic material including aramid fiber or glass fiber, and the chord modulus may be 30 Gpa to 70 ?quot;.

[0023] Additionally, the tensile member may be composed of steel wire and have a chord modulus of 150 GPa to 200 GPa.

[0024] In addition, the jacket is made of high density polyethylene (HDPE) or medium density polyethylene (MDPE) material, and the Young's modulus may be 400 MPa to 1000 MPa.

[0025] Here, the reinforcing layer may be a reinforcing tape that is attached to wrap the waterproofing member.

[0026] In this case, the reinforcing layer may be composed of a metal material.

[0027] And, the metal material may be composed of one or more of aluminum, steel, and chromium.

[0028] In addition, an adhesive is additionally included so that both ends of the reinforcing tape can be overlapped and joined in the width direction, and in the process of both ends of the reinforcing tape being joined by the adhesive, the waterproofing member can be joined together by the adhesive.

[0029] And, the waterproof tape can be bonded to at least a portion of the inner surface of the overlapping end area of ​​the reinforcing layer by the adhesive.

[0030] Here, the ratio of the Young's modulus of the tube member to the Young's modulus of the outer jacket may be 0.2 to 1.0.

[0031] In this case, the ratio of (Young's modulus X cross-sectional area) of the tube member to (Young's modulus X cross-sectional area) of the outer jacket may be 4 to 10.

[0032] And, in a temperature range of -40°C to 70°C, the linear coefficient of thermal expansion of the tensile member may be smaller than the linear coefficient of thermal expansion of the jacket.

[0033] Additionally, the value of (linear coefficient of thermal expansion X cross-sectional area) of the tensile member may be smaller than the value of (linear coefficient of thermal expansion X cross-sectional area) of the tensile member of the outer jacket.

[0034] According to the optical cable according to the present invention, the number of optical units constituting the core portion is reduced, thereby minimizing the overall outer diameter and weight of the optical cable, while optimizing the outer diameter and physical properties of each of the tensile member and optical units constituting the core portion, thereby significantly improving the mechanical properties of the optical cable, such as tensile strength, long-term reliability, and compression characteristics.

[0035] In addition, according to the optical cable according to the present invention, the outer jacket stripping operation of the optical cable can be performed quickly and safely by applying a reinforcing layer that wraps the core portion instead of a separate binding layer for binding the tube member or waterproof tape of the optical unit.

[0036] In addition, according to the optical cable according to the present invention, both ends of the reinforcing layer are joined by an adhesive, and during the process of joining both ends of the reinforcing layer, at least a portion of the waterproof tape inside the both end areas of the reinforcing layer is joined together, so that when the reinforcing layer is removed, the waterproof tape is removed together or is easily removed, thereby improving workability such as stripping and connecting.

[0037] Figure 1 illustrates a cross-sectional view of one embodiment of an optical cable according to the present invention.

[0038] Figure 2 illustrates a cross-sectional view of another embodiment of an optical cable according to the present invention.

[0039] Figure 3 shows a partial enlarged view of the embodiment shown in Figure 2.

[0040] Figure 4 illustrates a cross-sectional view of another embodiment of an optical cable according to the present invention.

[0041] Figure 5 illustrates a cross-sectional view of another embodiment of an optical cable according to the present invention.

[0042] 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.

[0043] FIG. 1 illustrates a cross-sectional view of one embodiment of an optical cable (100) according to the present invention, FIG. 2 illustrates a cross-sectional view of another embodiment of an optical cable (100) according to the present invention, and FIG. 3 illustrates a partial enlarged view of the embodiment illustrated in FIG. 2.

[0044] As illustrated in FIGS. 1 and 2, an optical cable (100) according to the present invention may be configured to include a core portion (30) including a tensile member (10); a plurality of optical units (20) arranged around the periphery of the tensile member (10) and including a plurality of optical fibers (21) and a tube member (25) accommodating the plurality of optical fibers (21); a waterproof member (40) wrapping around the outer side of the core portion (30); and a reinforcing layer (40) wrapping around the outer periphery of the waterproof member (40) and bonded together with at least a portion of the waterproof member (40) inside.

[0045] Each of the plurality of optical units (20) may be configured such that at least a portion thereof is in contact with the outer surface of the tensile member (10) and is twisted in one direction or the SZ direction (twisted in the S direction and then twisted again in the Z direction) with the tensile member at a twist pitch of 60 millimeters (mm) to 900 millimeters (mm).

[0046] In addition, the outer diameter (D) of the optical cable (100) may be configured to be smaller than 5 times the outer diameter (d1) of the tension member (10).

[0047] An optical cable (100) according to the present invention may be formed with a core portion (30) including one tensile member (10) and a plurality of optical units (20) inside, and a tensile member (10) for reinforcing tensile force may be provided inside the core portion (30) of the optical cable (100) and a plurality of optical units (20) may be arranged around the tensile member (10) to reinforce the tensile force.

[0048] Here, the center of one tensile member (10) inside the core portion (30) of the optical cable (100) may not be arranged at the center of the core portion (30). That is, in a state where the center of one tensile member (10) is eccentric from the center of the core portion (30), the tensile member (10) and a plurality of optical units (20) arranged around it may be provided in a combined state inside the core portion (30).

[0049] Preferably, the core part (30) of the optical cable (100) may be composed of one tensile member (10) and two or three optical units (20). For example, the optical cable (100) according to the present invention may be an optical cable (100) having a 1+2 structure in which one tensile member (10) is arranged inside the core part (30) and two optical units (20) are arranged around it, as in the embodiment illustrated in FIG. 1, and may be an optical cable (100) having a 1+3 structure in which one tensile member (10) is arranged inside the core part (30) and three optical units (20) are arranged around it, as in the embodiment illustrated in FIG. 2.

[0050] The above tensile member (10) suppresses deformation of the overall optical cable (100) and plays a role in improving the tensile strength of the optical cable (100). The material of the above tensile member (10) may be a high-strength fiber such as an aramid yarn, a glass yarn, a synthetic resin in which a reinforcing fiber is combined, a fiber reinforced plastic (FRP), a fiber glass epoxy rod, a zinc-plated steel wire, a carbon fiber, etc.

[0051] Preferably, the tensile member (10) is made of a reinforced plastic material including aramid fiber or glass fiber and having a chord modulus of 30 GPa to 70 GPa, or the tensile member (10) may be made of a steel wire having a chord modulus of 150 GPa to 200 GPa.

[0052] Here, chord modulus is one of the material properties measured by the test method according to the standard ASTM D3039, and means the slope between the point where the strain is 0.1% and the point where the strain is 0.3% on the stress-strain curve below the elastic limit of the material.

[0053] The cross-sectional shape of the above tensile member (10) may be circular, and the outer diameter (d1) of the above tensile member (10) may be configured to be 2.2 millimeters (mm) or more, preferably in the range of 2.3 millimeters (mm) to 2.7 millimeters (mm), and may be configured to be larger than 1 / 5 times the outer diameter (D) of the optical cable (100). If the outer diameter (d1) of the above tensile member (10) is less than 2.2 millimeters (mm) or less than or equal to 1 / 5 of the outer diameter (D) of the optical cable (100), the tensile strength, durability, heat shrinkage characteristics, etc. are deteriorated, so that the outer jacket (60) of the optical cable (100) connected to the connection box may be separated from the core portion (30), or the tensile member (10) may be damaged or deformed in the internal space of the connection box, thereby causing damage to a plurality of optical units (20) arranged around the tensile member (10).

[0054] As shown in FIGS. 1 and 2, the optical cable (100) according to the present invention may have two or three optical units (20) around the tension member (10), and each optical unit (20) may be configured to include a plurality of optical fibers (21) and a tube member (25) that wraps the plurality of optical fibers (21).

[0055] The cross-sectional shape of the above light unit (20) may be circular, and the outer diameter (d2) of the above light unit (20) may be configured to be 2.1 millimeters (mm) or more, preferably in the range of 2.2 millimeters (mm) to 2.6 millimeters (mm).

[0056] The optical cable (100) according to the present invention is configured such that the outer diameter (d2) of the optical unit (20) is 2.1 millimeters (mm) or more, thereby sufficiently improving the mechanical rigidity of the optical unit (20), thereby excellently preventing the shape deformation such as breakage, bending, twisting or breaking of the tube member (25) constituting the optical unit (20) inside the connection box.

[0057] The optical fiber (21) constituting the above optical unit (20) is generally configured as a double-cylindrical structure in which a portion called a core in the center is surrounded by a portion called a cladding on the main surface. Here, the core uses a glass optical fiber (21) made of silica having a high refractive index, and the cladding uses glass or synthetic resin made of silica having a relatively lower refractive index than the core, thereby allowing light passing through the center to undergo total reflection and transmit a signal.

[0058] The outer diameter of the optical fiber (21) may be 160 micrometers (㎛) to 250 micrometers (㎛).

[0059] The optical fiber (21) may include a protective coating layer to protect the core and cladding, and may include a coloring coating layer made of a polymer resin on the outer surface of the optical fiber (21) to identify each core wire.

[0060] In addition, a tube member (25) may be provided on the outside of the optical fiber (21) to configure an optical unit (20). Meanwhile, in the embodiment illustrated in FIG. 1, two optical units (20) are illustrated as each containing six optical fibers (21) therein, and in the embodiment illustrated in FIG. 2, three optical units (20) are illustrated as each containing 24 optical units (20) therein, but this is not limited thereto, and the number of optical fibers (21) accommodated in each optical unit (20) may be increased or decreased depending on the capacity or size of the optical communication line.

[0061] The tube member (25) of the above optical unit (20) may be formed of a loose tube, and the loose tube material may be composed of a thermoplastic polymer resin, polybutylene terephthalate (PBT), polycarbonate (PC), polyethylene (PE), polypropylene (PP), thermoplastic resin, etc.

[0062] Here, the Young's Modulus of the tube member (25) made of the polymer material is configured in the range of 1000 MPa to 3000 MPa, and through this, the tube member (25) secures excellent mechanical strength, thereby maintaining the circularity of the optical unit (20) and stably protecting the optical fiber (21) accommodated inside the optical unit (20) from pressure or deformation applied to the optical unit (20).

[0063] If the Young's Modulus of the above tube member (25) is less than 1000 MPa, the mechanical strength of the tube member (25) is reduced, which may cause optical loss due to the optical fiber (21) being compressed, whereas if the Young's Modulus is more than 3000 MPa, the flexibility of the optical unit (20) is reduced, which may cause breakage.

[0064] And the thickness of the above tube member (25) can be preferably configured in the range of 0.2 millimeters (mm) to 0.4 millimeters (mm) in order to secure mechanical strength while minimizing the outer diameter (d2) of the optical unit (20).

[0065] A plurality of optical units (20) are arranged to be twisted so as to have a twist pitch of 60 millimeters (mm) to 900 millimeters (mm) while contacting the outer surface of the tensile member (10), and the plurality of optical units (20) can be twisted in a spiral shape (SZ twist) by repeating one direction or clockwise (S twist) and counterclockwise (Z twist) along the longitudinal direction of the tensile member (10).

[0066] Here, if the twist pitch of the plurality of optical units (20) is less than 60 millimeters (mm), excessive bending stress is applied to the optical fiber (21), which deteriorates the optical transmission characteristics, or the twist is released by the self-restoring force of the plurality of optical units (20), so that the internal structure of the core part (30) cannot be stably maintained, and if the twist pitch exceeds 900 millimeters (mm), the flexibility of the optical cable (100) is reduced, or excessive stress is applied to the optical fiber (21) due to shrinkage in a low-temperature environment, so that optical loss may occur.

[0067] The optical cable (100) according to the present invention may include a waterproof member (40) that wraps around the outer circumference of the core portion (30).

[0068] The above waterproofing member (40) may be configured to wrap around the outer side of the core portion (30) in a spiral shape in the transverse or longitudinal direction.

[0069] Preferably, the waterproof member (40) may be composed of a waterproof tape that wraps the outer side of a core portion (30) composed of one tensile member (10) and a plurality of light units (20) in a longitudinal direction.

[0070] The above waterproofing member (40) surrounds the outer side of the core part (30) in a longitudinal direction and is wrapped again by the reinforcing layer (50) and is simultaneously bonded by the reinforcing layer (50) so that the longitudinal state of the waterproofing member (40) is maintained, so that a separate binding member for bonding or binding the waterproofing member (40) to the outer side of the waterproofing member (40) can be omitted.

[0071] Meanwhile, conventional optical cables are configured by wrapping a binding material such as a binder around the outer circumference of a waterproof member, so that when stripping the outer jacket (60), a separate task of removing the binding material using a stripping knife is required. However, the present invention omits the binding material on the outer side of the waterproof member (40), thereby reducing the time required for stripping the binding material and preventing damage to the optical unit (20) during stripping.

[0072] As illustrated in FIG. 3, the waterproofing member (40) can be bonded to at least a portion of the inner surface of the reinforcing layer (50) by an adhesive (90) applied for bonding the reinforcing layer (50). A detailed description of the method by which the waterproofing member (40) is bonded together during the bonding process of the reinforcing layer (50) by the adhesive will be postponed.

[0073] Since the above waterproofing member (40) can maintain a state in which at least a portion thereof is bonded or joined to the reinforcing layer (50), when a worker strips the outer jacket (60) with a stripping tool such as a ring cut and then pulls the reinforcing layer (50) inside the outer jacket (60) in the longitudinal direction, the reinforcing layer (50) and the waterproofing member (40) can be removed simultaneously, thereby improving the workability of the stripping or connecting work of the optical cable.

[0074] Specifically, when the outer jacket (60) is cut by ring cutting, the reinforcing layer (50) that is at least partially bonded to the outer jacket (60) and the waterproof member (40) that is at least partially bonded and joined to the reinforcing layer (50) are also cut simultaneously, so that the outer jacket stripping operation of the optical cable can be performed quickly and easily. In addition, when the reinforcing layer (50) is cut by ring cutting separately from the outer jacket (60), the waterproof member (40) that is at least partially bonded to the reinforcing layer (50) is also cut simultaneously, so that the stripping operation or subsequent connection operation can be performed quickly as well.

[0075] The above reinforcing layer (50) may be made of a material that is easy to detect metal, and preferably, the above reinforcing layer (50) may be made of a metal material tape such as an aluminum tape.

[0076] The above reinforcing layer (50) wraps around the outside of the core part (30) composed of one tensile member (10) and a plurality of optical units (20), so that the core part (30) is formed with an outer shape close to a circle, thereby improving the circularity of the optical cable (100) and stably maintaining the internal structure of the core part (30) by providing the outer jacket (60). At the same time, the tensile member (10) and the optical unit (20) are joined together.

[0077] That is, since a plurality of optical units (20) arranged to be twisted in one direction or the SZ direction so as to have the aforementioned twist pitch range on the outer surface of one tensile member (10) and the outer surface of the one tensile member (10) are twisted and joined by the reinforcing layer (50), the optical cable (100) is stably maintained in the twisted state of the plurality of optical units (20) arranged in contact with the outer surface of the tensile member (10) and the union state between the plurality of optical units (20) and the tensile member (10), so that a separate binding member for joining or binding the plurality of optical units (20) on the outer surface of the plurality of optical units (20) as in the prior art can be omitted.

[0078] Accordingly, when performing the stripping operation of the outer jacket (60) of the optical cable (100) according to the present invention, the removal of the binding member wrapping the outer side of the tube member (25) of the optical unit (20) is unnecessary, so that damage to the optical unit (20) caused by a stripping knife used for removing the existing binding member can be prevented, and the stripping operation of the outer jacket (60) can be improved.

[0079] FIG. 3 is an enlarged view of area A of the embodiment illustrated in FIG. 2, and as illustrated in FIG. 3, the reinforcing layer (50) may include an adhesive (90) that can be bonded so that both ends of the reinforcing layer (50) overlap at least a portion of the width direction of the reinforcing layer (50) in order to surround the outer side of the core portion (30) in a longitudinal manner and bond it.

[0080] Here, the adhesive (90) may be included in a form such as being partially disposed at the widthwise end of the reinforcing layer (50), forming an adhesive layer on one surface of the reinforcing layer (50), or coating the entire reinforcing layer (50). The adhesive (90) may be a material capable of heat-melting, and by laminating both ends of the reinforcing layer (50) and then heat-melting them in the longitudinal direction of the cable, the reinforcing layer (50) and the waterproofing member (40) therein may be bonded at once. That is, the adhesive (90) provided on the inner circumferential surface of the outer end of the overlapping area (OL) for bonding the reinforcing layer (50) can seep into the surroundings during an adhesive process such as heat-melting, and bond at least a portion of the waterproofing member (40) therein together.

[0081] In this case, since the reinforcing layer (50) is maintained in an overlapping state at both ends of the reinforcing layer (50) by the adhesive (90), a separate binding member for bonding or binding the reinforcing layer (50) on the outside of the reinforcing layer (50) can be omitted.

[0082] In addition, an outer jacket (60) is provided on the outermost layer of the reinforcing layer (50) of the optical cable (100) according to the present invention to protect the internal structure of the optical cable (100).

[0083] The thickness of the outer jacket (60) may be selected in consideration of the mechanical strength, tensile strength, and durability of the optical cable (100), and may preferably be configured in the range of 0.8 millimeters to 1.2 millimeters (mm).

[0084] The above outer jacket (60) may be made of, for example, high density polyethylene (HDPE) or medium density polyethylene (MPDE) material.

[0085] The Young's Modulus of the outer jacket (60) made of the above polymer material can be configured in the range of 400 MPa to 1000 MPa. Therefore, the outer jacket (60) can sufficiently implement physical properties such as mechanical strength, tensile strength, and durability, and can excellently maintain the circularity of the optical cable (100).

[0086] In addition, the ratio of the Young's modulus of the tube member (25) constituting the optical unit (20) to the Young's modulus of the outer jacket (60) may be 0.2 to 1.0. If the Young's modulus ratio of the tube member (25) and the outer jacket (60) is less than 0.2, the mechanical rigidity of the tube member (25) is insufficient, so that the inner tube member (25) may be crushed by pressing of the outer jacket (60) or external force, thereby causing optical damage. On the other hand, if the Young's modulus ratio of the tube member (25) and the outer jacket (60) is greater than 1.0, the mechanical rigidity of the outer jacket (60) is insufficient, so that the circularity of the optical cable (100) cannot be maintained.

[0087] And, the ratio of the product of the Young's modulus and the cross-sectional area of ​​the tube member (25) to the product of the Young's modulus and the cross-sectional area of ​​the outer jacket (60) (Young's modulus X cross-sectional area) may be in the range of 4 to 10. When the (Young's modulus X cross-sectional area) ratio between the tube member (25) and the outer jacket (60) is less than 4, the bonding force between the tube members (25) of the plurality of optical units (20) and the outer jacket (60) may be weakened, and thus the tube members (25) of the plurality of optical units (20) may be separated from the inner surface of the outer jacket (60). On the other hand, when the (Young's modulus X cross-sectional area) ratio between the tube member (25) and the outer jacket (60) exceeds 10, the mechanical rigidity of the outer jacket (60) is insufficient, and thus the circularity of the optical cable (100) cannot be maintained.

[0088] And, in the temperature range of -40°C to 70°C, the linear coefficient of thermal expansion of the tensile member (10) may be configured to be smaller than the linear coefficient of thermal expansion of the outer jacket (60), and the product of the linear coefficient of thermal expansion of the tensile member (10) and the cross-sectional area (linear coefficient of thermal expansion X cross-sectional area) may be configured to be smaller than the product of the linear coefficient of thermal expansion of the outer jacket (60) and the cross-sectional area (linear coefficient of thermal expansion X cross-sectional area). In this case, in the temperature range of 40°C to 70°C, which is the operating temperature of the optical cable (100), shrinkage of the outer jacket (60) is prevented, and long-term reliability is improved, so that the internal configuration of the outer jacket (60) can be stably protected.

[0089] The optical cable (100) according to the present invention may be configured by additionally embedding a plurality of auxiliary tension members (10) in the outer jacket (60). The plurality of tension members (10) are configured to have a circular cross-section and may be arranged inside the outer jacket (60) along the longitudinal direction of the outer jacket (60).

[0090] Figures 4 and 5 illustrate cross-sectional views of another embodiment of an optical cable (100) according to the present invention. Figure 4 illustrates an embodiment in which a plurality of auxiliary tension members (70) are provided inside the outer jacket (60) of an optical cable (100) having a 1+2 structure, and Figure 5 illustrates an embodiment in which a plurality of auxiliary tension members (70) are provided inside the outer jacket (60) of an optical cable (100) having a 1+3 structure.

[0091] The material of the above plurality of auxiliary tension members (70) may be a polymer resin such as aramid yarn, Kevlar armid yarn, glass yarn, fiber glass epoxy rod, high-strength fiber, steel wire, polyethylene, etc., which provides sufficient rigidity, similar to the tension member (10).

[0092] In the embodiment illustrated in FIGS. 4 and 5, two of the plurality of tensile members (70) are provided inside the outer jacket (60), but the number of the plurality of auxiliary tensile members (70) may be provided as two or more in response to the physical properties such as mechanical strength, tensile strength, and durability required for the optical cable (100).

[0093] Preferably, the plurality of auxiliary tensile members (70) are provided so that a pair of auxiliary tensile members (70) are arranged at symmetrical positions centered on the core portion (30), thereby uniformly reinforcing the tensile force in the circumferential direction of the outer jacket (60) and alleviating the low-temperature shrinkage phenomenon of the outer jacket (60).

[0094] Specifically, in the case where the optical cable (100) according to the present invention has a 1+2 structure inside the core portion (30), the outer diameter (D) of the optical cable (100) may be in the range of 8.5 millimeters to 10 millimeters (mm), and the weight per unit kilometer (km) of the optical cable (100) may be in the range of 70 kilograms to 80 kilograms (kg). In addition, in the case where the optical cable (100) according to the present invention has a 1+3 structure inside the core portion (30), the outer diameter (D) of the optical cable (100) may be in the range of 9.5 millimeters to 11 millimeters (mm), and the weight per unit kilometer of the optical cable (100) may be in the range of 80 kilograms to 90 kilograms (kg).

[0095] In this way, the optical cable (100) according to the present invention has a 1+2 structure or a 1+3 structure inside the core portion (30), thereby minimizing the outer diameter (D) and weight of the optical cable (100), while optimizing the size and properties of one tensile member (10) and each optical unit (20) constituting the core portion (30), thereby maintaining the internal structure of the core portion (30) and ensuring excellent tensile strength, compressive characteristics, long-term reliability, etc. of the optical cable (100).

[0096] Furthermore, the optical cable (100) according to the present invention can omit a binding member for binding the outer side of a plurality of optical units (20) or waterproof members (40) as internal components, wrap the core part (20) with a waterproof member (40) in the form of a waterproof tape, and bond both end areas of a reinforcing layer (50) to the outer side of the waterproof member (40) with an adhesive (90), so that the waterproof member and the reinforcing layer are bonded together, thereby improving workability when performing tasks such as peeling off the outer jacket or reinforcing layer and connecting or branching an optical unit (20).

[0097] 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. In optical cables, A core portion comprising a plurality of optical units including a single tensile member and a plurality of optical fibers and a tube member for accommodating the plurality of optical fibers; A waterproof member covering the outer surface of the core portion; A reinforcing layer that surrounds the outer perimeter of the waterproofing member and is bonded to at least a portion of the waterproofing member; and An optical cable comprising an outer jacket wrapping around the outer perimeter of the reinforcing layer.

2. In paragraph 1, An optical cable characterized in that the outer diameter of the optical cable is smaller than five times the outer diameter of the tensile member.

3. In paragraph 1, An optical cable characterized in that each of the plurality of optical units is at least partially in contact with the outer surface of the tension member and is twisted in the SZ direction with the tension member at a twist pitch of 60 millimeters (mm) to 900 millimeters (mm).

4. In paragraph 1, An optical cable characterized in that the above waterproofing member is a waterproofing tape that is terminated to wrap the core portion.

5. In paragraph 1, An optical cable characterized in that the center of the above one tensile member is not located at the center of the core portion.

6. In paragraph 1, An optical cable characterized in that a plurality of auxiliary tension members are embedded in the outer jacket.

7. In paragraph 6, An optical cable characterized in that the plurality of auxiliary tension members are arranged symmetrically around the core portion.

8. In paragraph 1, An optical cable characterized in that the number of optical units is 2 or 3.

9. In paragraph 1, An optical cable characterized in that the outer diameter of the optical unit is 2.1 millimeters (mm) or more, and the outer diameter of the tensile member is 2.2 millimeters (mm) or more.

10. In paragraph 1, An optical cable characterized in that the tube member of the above optical unit contains polybutylene terephthalate (PBT) or polypropylene (PP) as a base resin and has a Young's modulus of 1000 MPa to 3000 MPa.

11. In paragraph 1, An optical cable characterized in that the above tensile member is composed of a reinforced plastic material including aramid fiber or glass fiber, and has a chord modulus of 30 GPa to 70 GPa.

12. In paragraph 1, An optical cable characterized in that the above tensile member is composed of steel wire and has a chord modulus of 150 GPa to 200 GPa.

13. In paragraph 1, An optical cable characterized in that the jacket is composed of high density polyethylene (HDPE) or medium density polyethylene (MDPE) material and has a Young's modulus of 400 MPa to 1000 MPa.

14. In paragraph 1, An optical cable characterized in that the above reinforcing layer is a reinforcing tape that is terminated to wrap the above waterproofing member.

15. In paragraph 1, An optical cable characterized in that the above reinforcing layer is composed of a metal material.

16. In paragraph 15, An optical cable characterized in that the metal material comprises at least one of aluminum, steel, and chromium.

17. In paragraph 14, An adhesive is additionally included so that both ends of the reinforcing tape can be overlapped and joined in the width direction, An optical cable characterized in that the waterproofing member is bonded together by the adhesive during the process in which both ends of the reinforcing tape are bonded by the adhesive.

18. In paragraph 17, An optical cable characterized in that the waterproof tape is bonded to at least a portion of the inner surface of the overlapping end area of ​​the reinforcing layer by the adhesive.

19. In paragraph 1, An optical cable characterized in that the ratio of the Young's modulus of the tube member to the Young's modulus of the outer jacket is 0.2 to 1.

0.

20. In paragraph 19, An optical cable characterized in that the ratio of (Young's modulus X cross-sectional area) of the above tube member to (Young's modulus X cross-sectional area) of the above outer jacket is 4 to 10.

21. In paragraph 1, A lightweight optical cable characterized in that the linear coefficient of thermal expansion of the tensile member is smaller than the linear coefficient of thermal expansion of the jacket in a temperature range of -40°C to 70°C.

22. In paragraph 21, An optical cable characterized in that the value of (linear coefficient of thermal expansion X cross-sectional area) of the above tensile member is smaller than the value of (linear coefficient of thermal expansion X cross-sectional area) of the tensile member of the outer jacket.

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