Rollable optical fiber ribbon and optical cable comprising same

Abstract

The present invention relates to a rollable optical fiber ribbon and an optical cable comprising same. More specifically, the present invention relates to a rollable optical fiber ribbon and an optical cable comprising same, which have a coloring layer on the outermost layer of each optical fiber such that an optical fiber ribbon is readily distinguished from an individual optical fiber through various colors, maintain sufficient bonding strength between the optical fiber and a joint part so as to enable width-wise rolling, and can prevent damage, due to the joint part, to the optical fiber coloring layer during optical fiber separation.

Description

Rollable optical fiber ribbon and optical cable including the same

[0001] The present invention relates to a rollable optical fiber ribbon and an optical cable including the same. More specifically, the present invention relates to a rollable optical fiber ribbon and an optical cable including the same, which comprises a coloring layer on the outermost layer of each optical fiber, thereby facilitating the distinction between the optical fiber ribbon and individual optical fibers through various colors, maintains sufficient bonding strength between the optical fiber and the joint to enable widthwise rolling, and prevents damage to the optical fiber coloring layer caused by the joint during the separation process of the optical fiber.

[0002] With the recent increase in demand for ultra-high-speed communications, the demand for optical cable-based communication networks is also steadily increasing. Optical cables offer significant bandwidth and are lightweight and compact, making them advantageous for building ultra-high-speed transmission networks.

[0003] In order to build a large-capacity optical communication network, an optical cable is being used that accommodates a plurality of optical fiber ribbons assembled by joining multiple optical fibers in parallel inside the outer jacket or tube of the optical cable, and in particular, the use of high-density optical cables that accommodate rollable ribbons that have a structure that allows width-wise rolling by joining adjacent optical fibers among multiple optical fibers through joints intermittently arranged along the length direction is increasing.

[0004] Here, the optical fiber ribbon and individual optical fibers constituting the optical cable must be identifiable, and in order to identify the optical fiber ribbon and individual optical fibers, various colors can be applied to the outermost surface of each optical fiber through a coloring layer, thereby enabling identification of the optical fiber ribbon and individual optical fibers from the outside.

[0005] Meanwhile, optical fibers forming a general optical fiber ribbon having joints that are continuously wrapped along the length of the optical fiber must have a smooth surface for medium stabilization, whereas optical fibers forming a rollable optical fiber ribbon having joints that are intermittently arranged along the length of the optical fiber have a smaller contact area with the joints than optical fibers in a general optical fiber ribbon, and therefore require a relatively stronger bonding strength per unit area between the optical fiber and the joints than in a general optical fiber ribbon in order to prevent unwanted separation between the optical fiber and the joints.

[0006] In addition, in order to maintain the shape of the optical fiber ribbon in a state of rolling in the width direction, the rollable optical fiber ribbon should be such that the optical fibers are mutually bonded at the joints, and at the same time, when the mutually bonded optical fibers must be separated during the process of connecting the optical fiber ribbon, the separation of the optical fibers should be easy, and further, the surface layer of the optical fiber should be prevented from being damaged during the process of separating the optical fibers.

[0007] Typically, the bonding strength of a rollable optical fiber ribbon can be controlled by adjusting the properties of the joints. However, if viscosity increases during the process of adjusting the properties of the joints, it becomes difficult to consistently spray the bonding agent from the equipment nozzle, hindering the optical fiber ribbon production process. Furthermore, excessive viscosity increases can cause the optical fiber coloring layer to break or be damaged by the joints during optical fiber separation.

[0008] On the other hand, if the viscosity falls below a certain level during the process of controlling the properties of the joint, the shape of the joint is deformed due to the thixotropy phenomenon and the shear force of the joint is reduced, making it impossible to achieve sufficient bonding strength between the joint and the optical fiber coloring layer.

[0009] Accordingly, there is a great demand for a rollable optical fiber ribbon that has a coloring layer on the outermost layer of each optical fiber to facilitate the distinction of optical fiber ribbons and individual optical fibers through various colors, maintains sufficient bonding strength between the optical fiber and the joint to enable width-wise rolling, and prevents damage to the optical fiber coloring layer by the joint during the separation process of the optical fiber.

[0010] The present invention aims to provide a rollable optical fiber ribbon and an optical cable including the same, which has a coloring layer on the outermost layer of each optical fiber to facilitate the distinction between the optical fiber ribbon and individual optical fibers through various colors, maintains sufficient bonding strength between the optical fiber and the bonding portion to enable width-wise rolling, and prevents damage to the optical fiber coloring layer by the bonding portion during the process of separating the optical fiber.

[0011] In order to solve the above problem, the present invention can provide a rollable optical fiber ribbon, which comprises a core; a cladding layer surrounding the core; a coating layer surrounding the cladding layer; and a coloring layer surrounding the coating layer; a plurality of optical fibers arranged in parallel in the longitudinal direction, and a plurality of joints joining a pair of adjacent optical fibers among the plurality of optical fibers, wherein the joints are intermittently arranged along the longitudinal direction of the optical fibers, the joints are arranged in a portion of a circumferential direction of the optical fibers, and the arithmetic mean roughness (Ra) of the surface of the coloring layer according to the JIS B0601 standard is 0.15 micrometers (μm) to 0.48 micrometers (μm).

[0012] Additionally, the outer diameter of the clad layer may be 80 micrometers (μm) to 125 micrometers (μm), and the thickness of the coloring layer may be 3.0 micrometers (μm) to 10.0 micrometers (μm).

[0013] In addition, the joint can be formed by applying a jointing resin to the surface of the coloring layer of the optical fiber and then UV curing the resin.

[0014] Here, the density of the joint is 0.8 g / cm 3 1.4 g / cm 3 , the tensile strength may be 2.0 MPa to 22 MPa, the elongation may be 40% to 210%, the elastic modulus may be 5 MPa to 90 MPa at 2.5% strain, and the viscosity may be 80 mPa·s to 800 mPa·s at 25°C.

[0015] In addition, in order to solve the above problem, the present invention can provide an optical cable characterized by including the above-described rollable optical fiber ribbon, an optical unit including a plurality of rollable optical fiber ribbons; and a first assembly member that accommodates the plurality of rollable optical fiber ribbons; a cable core including one or more of the optical units; and an outer jacket that wraps the cable core.

[0016] Additionally, the cable core can collect multiple optical units.

[0017] Here, one or more notches arranged in the inner region of the outer jacket and an identification means capable of identifying the position of the notches may be provided.

[0018] In this case, a ripcord can be accommodated inside the notch.

[0019] And, it may include a second assembly member that wraps around the outer circumference of the cable core.

[0020] In addition, at least one pair of tension members may be embedded in the outer jacket in the longitudinal direction of the optical cable, and an identification means for identifying the position of the tension members may be provided.

[0021] And, in order to solve the above problem, the present invention provides a method for manufacturing an optical fiber for a rollable optical fiber ribbon, which includes a plurality of optical fibers and a plurality of joints intermittently arranged along the longitudinal direction of the optical fibers, the method comprising the steps of: drawing a bare fiber including a core and a cladding surrounding the core from a preform; applying a coating material to form a coating layer on the bare fiber; applying a coloring material after the step of applying the coating material; and UV curing at least one of the coating material and the coloring material; wherein the coloring material includes a resin mixed with colored pigment particles, and in the step of forming the coloring layer, the atmosphere is characterized in that the concentration of oxygen is in a range of more than 3500 ppm and less than 20000 ppm.

[0022] Here, a step of UV curing the coating material may be additionally included after the step of applying the coating material.

[0023] In this case, the volume ratio of oxygen and nitrogen in the atmosphere in the step of forming the coloring layer may be in the range of 1:4 to 1:9.

[0024] In addition, the optical fiber withdrawal speed during the UV curing may be 1000 mpm to 2100 mpm, the curing time may be 0.03 seconds to 0.1 seconds, and the degree of curing of the coloring layer may be in the range of 80% to 95%.

[0025] In addition, the coating layer includes a first coating layer that contacts and wraps the optical fiber; a second coating layer that contacts and wraps the colored layer, and a modulus of the first coating layer may be lower than a modulus of the second coating layer.

[0026] According to the rollable optical fiber ribbon and the optical cable including the same according to the present invention, since a coloring layer is provided on the outermost layer of each optical fiber constituting the optical fiber ribbon, the optical fiber ribbon and individual optical fibers can be identified, and by controlling the oxygen concentration in the process of performing the coloring process on each optical fiber, the surface roughness of the coloring layer of the optical fiber can be configured to be 0.15 micrometers (μm) to 0.48 micrometers (μm), thereby ensuring optimal bonding strength between the optical fiber and the joint.

[0027] FIG. 1 illustrates one embodiment of a rolled optical fiber ribbon according to the present invention in a dried state.

[0028] FIG. 2 illustrates a plan view of one embodiment of a rollable optical fiber ribbon according to the present invention.

[0029] FIG. 3 illustrates an enlarged cross-sectional view of one embodiment of a rollable optical fiber ribbon according to the present invention.

[0030] FIG. 4 illustrates an enlarged cross-sectional view of another embodiment of a rollable optical fiber ribbon according to the present invention.

[0031] FIG. 5 illustrates an enlarged cross-sectional view of another embodiment of a rollable optical fiber ribbon according to the present invention.

[0032] Figure 6 illustrates a separation strength measuring device for measuring the vertical separation strength at a joint of a rollable optical fiber ribbon according to the present invention.

[0033] Figure 7 illustrates a separation strength measuring device for measuring horizontal separation strength at a joint of a rollable optical fiber ribbon according to the present invention.

[0034] Figure 8 illustrates a state in which the optical fiber coloring layer is damaged in a rollable optical fiber ribbon according to the present invention.

[0035] FIG. 9 illustrates a cross-sectional view of one embodiment of an optical cable including a rollable optical fiber ribbon according to the present invention.

[0036] 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.

[0037] FIG. 1 illustrates one embodiment of a rolled-up state of a rollable optical fiber ribbon (100) according to the present invention, and FIG. 2 illustrates a plan view of one embodiment of a rollable optical fiber ribbon according to the present invention.

[0038] A rollable optical fiber ribbon (100) according to the present invention is configured by joining a plurality of optical fibers (10) in parallel, and an adjacent pair of optical fibers (10) among the plurality of optical fibers (10) can be joined through a plurality of joints (20) intermittently arranged along the length direction of the optical fiber.

[0039] Referring to FIG. 1, when examining the cross-sectional structure of a plurality of optical fibers (10) constituting a rollable optical fiber ribbon (100) according to the present invention, each optical fiber (10) can be configured to include a core (11), a cladding layer (12), a coating layer (13), and a coloring layer (14).

[0040] The core (11) may be composed of glass or synthetic resin and transmits light. The clad layer (12) may be formed to surround the core (11).

[0041] The above cladding layer (12) uses glass or synthetic resin made of silica material with a relatively lower refractive index than the core (11), thereby allowing total reflection of light passing through the center of the optical fiber, thereby transmitting a signal.

[0042] The above coating layer (13) may be formed by coating the surface of the clad layer (12) with a material including at least one of acrylate, polyimide, and carbon. The coating layer (13) is configured to directly surround the clad layer (12) and serves to absorb external impact transmitted to the clad layer (12). The coating layer (13) may be composed of multiple layers having different physical properties, such as modulus, in order to safely protect internal components.

[0043] The coloring layer (14) is applied to the surface of the coating layer (13) with a material containing a coloring agent such as a colored or colorless pigment to impart color to the optical fiber (10), thereby enabling identification of the optical fiber from other optical fibers through color.

[0044] The rollable optical fiber ribbon (100) according to the present invention is configured to be rollable in the width direction, and each optical fiber (10) constituting the rollable optical fiber ribbon (100) has a coloring layer (14) on the outermost layer so that the optical fibers (10) can be mutually identified.

[0045] As illustrated in FIG. 2, a rollable optical fiber ribbon (100) according to the present invention is configured by joining a plurality of optical fibers (10) arranged in a longitudinal direction in parallel, and each adjacent pair of optical fibers (10) among the plurality of optical fibers (10) can be joined through a plurality of joints (20) intermittently arranged along the longitudinal direction of the optical fiber. Here, the joints (20) may again be a structure of a group in which a plurality of joint elements (not shown) are arranged spaced apart from each other.

[0046] The above-mentioned rollable optical fiber ribbon (100) may have a plurality of non-bonded portions in which not all optical fibers (10) are bonded in the longitudinal cross-section of the optical fiber.

[0047] The above-mentioned rollable optical fiber ribbon (100) can be configured by bonding each of a pair of optical fibers (10) arranged adjacently among a plurality of optical fibers arranged in parallel along the length direction.

[0048] In a rollable optical fiber ribbon (100) according to the present invention, adjacent pairs of optical fibers (10) among a plurality of optical fibers (10) are joined through a plurality of joints (20) intermittently arranged along the longitudinal direction of the optical fibers, so that the optical fiber ribbon (100) can be rolled in the width direction while the plurality of optical fibers (10) are maintained in a mutually joined state at the joints (20) and an unjoined state is maintained in the remaining area excluding the joints (20), and thus the optical fiber ribbon (100) can be efficiently accommodated in the internal space of the optical cable.

[0049] In this way, each optical fiber (10) constituting the rollable optical fiber ribbon (100) according to the present invention must be maintained in a mutually bonded state by sufficient bonding force at each joint (20), and at the same time, when the optical fiber ribbon is branched, in the process of separating each optical fiber (10) from the optical fiber ribbon (100), a pair of optical fibers (10) bonded to each other by each joint (20) must be smoothly separated without being damaged, and in addition, when separating an optical fiber having a colored layer, damage to the colored layer must be prevented.

[0050] Meanwhile, in the case of an optical fiber that constitutes a general optical fiber ribbon without a width-wise rolling function having a joint that continuously wraps along the length of the optical fiber, the surface of the optical fiber must be smooth for medium stabilization, whereas an optical fiber (10) that constitutes a rollable optical fiber ribbon (100) with an optical fiber having a coloring layer as in the present invention has a reduced joint area with the joint (20) compared to an optical fiber of a general optical fiber ribbon, and thus the surface of the optical fiber (10) can be formed relatively rough, thereby improving the joint strength due to the increase in the joint area between the optical fiber (10) and the joint (20).

[0051] However, even when a rollable optical fiber ribbon (100) is formed with an optical fiber having a coloring layer like the present invention, if the surface of the optical fiber (10) is formed relatively too rough and the bonding strength increases too much, the coloring layer may be damaged during the process of separating individual optical fibers from the ribbon.

[0052] Therefore, the surface roughness of the optical fiber (10) must be limited to an appropriate range, and the surface roughness, i.e., the surface roughness of the coloring layer as a measure of the surface roughness, must be controlled to an appropriate range to secure an appropriate bonding strength between the bonded optical fibers.

[0053] Specifically, the surface roughness of the coloring layer (14) of each optical fiber (10) constituting the rollable optical fiber ribbon (100) according to the present invention can be configured in a range of 0.15 micrometers (μm) to 0.48 micrometers (μm).

[0054] Here, the surface roughness of the coloring layer (14) of the optical fiber (10) refers to the arithmetic average roughness (Ra) of the JIS B0601:2001 (ISO 4287:1997) standard.

[0055] If the arithmetic mean roughness (Ra) of the surface of the coloring layer (14) of the optical fiber (10) is less than 0.15 micrometers (μm), the bonding area between the optical fiber (10) and the joint (20) is reduced, and thus a sufficient bonding state cannot be maintained between the optical fiber (10) and the joint (20), whereas if the surface roughness of the coloring layer (14) exceeds 0.48 micrometers (μm), the bonding force excessively increases as the bonding area between the optical fiber (10) and the joint (20) increases, and thus the optical fiber (10) may be damaged during the process of separating the optical fiber (10), and as a result, the optical transmission characteristics of the optical fiber (10) may deteriorate.

[0056] That is, the rollable optical fiber ribbon (100) according to the present invention can prevent the optical fiber (10) from being damaged during the process of separating the optical fiber (10) while allowing the optical fiber (10) to be bonded with sufficient bonding strength at each joint (20) of the optical fiber ribbon (100) by controlling the arithmetic mean roughness (Ra) of the surface of the coloring layer (14) of the optical fiber (10) within the above range.

[0057] The joint (20) of the rollable optical fiber ribbon (100) according to the present invention can be formed by UV curing or laser sintering various resins or resins such as UV curable resin or laser sintering powder, and the amount of resin or resin forming the joint (21) can be formed to be almost the same.

[0058] In order to allow the optical fiber ribbon (100) to roll while allowing the joint (20) to be clearly separated when the joined optical fiber (10) is separated, the elongation of the cured or sintered resin may be 40% to 210%, preferably 85% to 190%, and the density may be 0.8 g / cm. 3 1.4 g / cm 3 , preferably 1.0 g / cm 3 1.2 g / cm 3 It could be.

[0059] In addition, in order to enable the widthwise rolling or rolling state maintenance of the rollable optical fiber ribbon (100), the elastic cross modulus (Secant Modulus) of the joint (20) may be 5 MPa to 90 MPa, preferably 5 MPa to 74 MPa, at 2.5% strain.

[0060] And, in order to form a plurality of joints (20) intermittently arranged along the length direction of the optical fiber (10) in this way, the resin or the like must be applied accurately and quickly, but must have appropriate flowability to prevent dropping before hardening or sintering. Therefore, the viscosity of the joints (20) may be in the range of 80 mPa·s to 800 mPa·s, preferably 90 mPa·s to 520 mPa·s, at 30°C.

[0061] In addition, since the plurality of joints (20) must have a sufficiently large stress to maintain excellent joint strength of the joints (10) even after hardening or sintering and prevent cracking or breakage of the joints (20) due to external impact, the tensile strength of the joints (20) may be 2.0 MPa to 22 MPa, preferably 5 MPa to 18 MPa.

[0062] FIG. 3 illustrates an enlarged cross-sectional view of one embodiment of an optical fiber ribbon according to the present invention, FIG. 4 illustrates an enlarged cross-sectional view of another embodiment of an optical fiber ribbon according to the present invention, and FIG. 5 illustrates an enlarged cross-sectional view of yet another embodiment of an optical fiber ribbon according to the present invention.

[0063] The optical fiber ribbon (100) illustrated in FIGS. 3 and 4 is formed by splicing 12 general optical fibers (10) to satisfy the 3.22 mm (3,220 μm) limit of the width (w) of the 12-core optical fiber ribbon (100) based on the IEC standard or ANSI / ICEA standard related to optical fiber ribbons or optical cables. In order to do so, the optical fiber ribbon (100) can be spliced ​​so that most of the general optical fibers (10) having adjacent diameters (d1) of 230 μm to 270 μm are spliced ​​in a mutually external state.

[0064] That is, since the sum of the diameters (d1) of 12 optical fibers (10) having a diameter of 250 ㎛ is 3,000 ㎛, even if some optical fibers (10) are joined in a spaced state (see FIG. 5), most optical fibers (10) are joined in a mutually external state, and the optical fibers (10) can be joined to each other by each joining portion (20) arranged in a circumferential region of the cross section of each optical fiber in a pair of adjacently arranged optical fibers.

[0065] The embodiment illustrated in FIG. 4 is a case where the amount of resin disposed at one side of the optical fiber ribbon, for example, the lower side of the optical fiber ribbon, at the joint (20) of the optical fiber ribbon is reduced compared to the amount of resin disposed at the other side of the optical fiber ribbon, for example, the upper side of the optical fiber ribbon.

[0066] In addition, although it does not satisfy the IEC standard or the ANSI / ICEA standard, the optical fiber (10) constituting the optical fiber ribbon (100) may be arranged so as to be externally connected, as shown in FIGS. 3 and 4, with a diameter (d1) of 160 ㎛ or more and less than 230 ㎛.

[0067] As shown in Fig. 4, instead of the resin applied to the two-sided joints (20) of the optical fiber ribbon (100) being applied in equal amounts, even when the amount of resin applied to one-sided joints (20) is configured to be about 50% or less than the amount of resin applied to the other-sided joint area (20), not only is the rolling characteristic in one direction excellent when the optical fiber ribbon (100) is rolled, but the amount of resin can be reduced overall.

[0068] On the other hand, the optical fiber ribbon (100) illustrated in FIG. 5 is composed of 12 fine-diameter optical fibers (10) having a diameter (d2) of 220 ㎛ joined together, and the sum of the diameters (d2) of each optical fiber (10) is only 2,640 ㎛ at most, so there is room for the 3.22 mm (3,220 ㎛) width limit of the 12-core optical fiber ribbon (100).

[0069] When forming an optical fiber ribbon (100) by discontinuously joining optical fibers (10), as shown in FIG. 5, rather than joining the optical fibers (10) by external connection, the joining performance can be improved by forming a joint (20) by joining the optical fibers (10) with resin in a spaced state.

[0070] That is, when the optical fiber ribbon (100) is composed of 12 fine-diameter optical fibers (10) joined together, most of the optical fibers (10) are spaced apart from each other so that a joining area (20) is formed and can be joined together by each joining portion (20).

[0071] Furthermore, the present invention can provide a method for manufacturing an optical fiber (10) for a rollable optical fiber ribbon (100). The optical fiber (10) constituting the rollable optical fiber ribbon (100) according to the present invention can be manufactured by performing the steps of: drawing a bare optical fiber including a core (11) and a cladding layer (12) surrounding the core (11) from a preform; forming a coating layer (13) by applying a coating material on the bare optical fiber; forming a coloring layer (14) by applying a coloring material on the coating layer (13); and UV curing at least one of the coating material and the coloring material.

[0072] A plurality of optical fibers (10) constituting a rollable optical fiber ribbon (100) according to the present invention can be configured to include a core (11), a cladding layer (12), a coating layer (13), and a coloring layer (14) through the above manufacturing method.

[0073] Here, the coating layer (13) may be composed of one or more layers. Preferably, the coating layer (13) may include a first coating layer (13a) and a second coating layer (13b). Since the first coating layer (13a) directly wraps the clad layer (12), a material having a relatively low modulus may be used to absorb external impact transmitted to the clad layer (12), and the second coating layer (13b) may be a material having a relatively high modulus to alleviate external impact. In addition to the first coating layer (13a) and the second coating layer (13b), the coating layer may include an additional coating layer to protect the core (11) and the clad layer (12).

[0074] The above coloring layer (14) is formed by coating so as to surround the coating layer (13). The coloring layer (14) may be composed of a material that mixes a coloring agent and a resin to impart color to the optical fiber (10), and preferably, the coloring layer (14) may be composed of colored pigment particles and a resin containing a certain concentration of oxygen.

[0075] The above coloring layer (14) can be formed on the outermost surface of the optical fiber (10) through a coloring process in which a UV-curable resin mixed with colored pigment particles is applied to the surface of the coating layer (13) that has been cured or not, and then the resin is UV-cured in a process atmosphere containing oxygen and nitrogen.

[0076] Each optical fiber (10) constituting the rollable optical fiber ribbon (100) according to one embodiment of the present invention may have an outer diameter excluding the coating layer (13) and the coloring layer (14), i.e., an outer diameter of the cladding layer, of 80 micrometers (μm) to 125 micrometers (μm). In addition, the thickness of the coating layer (13) may be determined depending on the purpose.

[0077] And, each of the optical fibers (10) may have a coloring layer (14) having a thickness of 3.0 micrometers (μm) to 10.0 micrometers (μm). If the coloring layer (14) has a thickness of less than 3.0 micrometers (μm), the identification of the optical fiber (10) may be reduced, whereas if the coloring layer (14) has a thickness of more than 10.0 micrometers (μm), there is a disadvantage in that the cost of the coloring process of the optical fiber unnecessarily increases.

[0078] Meanwhile, in the past, in order to control the bonding strength of a rollable optical fiber ribbon (100), the physical properties of the bonding portion (20) such as viscosity (mPa·s), elongation (%), elastic modulus (MPa), and tensile strength (MPa) were controlled. However, in the case where only the physical properties of the bonding portion (20) were controlled to control the bonding strength, the spraying work of the bonding portion resin was difficult in the production process of the rollable optical fiber ribbon (100), which resulted in a decrease in productivity, and problems such as the destruction of the shape of the bonding portion (20) or the deterioration of the quality of the bonding portion (20).

[0079] Accordingly, in addition to controlling the properties of the joint (20), the rollable optical fiber ribbon (100) according to the present invention can control the arithmetic mean roughness (Ra) of the surface of the coloring layer (14) of the optical fiber (10) in the range of 0.15 micrometers (μm) to 0.48 micrometers (μm) by controlling the process variables in the coloring process, that is, the process of forming a coloring layer (14) on the outermost layer of the optical fiber (10) in the step of forming a coloring layer in the manufacturing method of the optical fiber for the rollable optical fiber ribbon, thereby controlling the contact area between the optical fiber (10) and the joint (20) to secure optimal bonding strength.

[0080] The coloring process of the optical fiber (10) includes a process of applying a resin containing colored pigment particles to the outer surface of the protective layer (13) of the optical fiber (10) being drawn out, and a process of UV-curing the applied resin in an ultraviolet (UV) curing device in which a coloring process atmosphere is formed to form a coloring layer.

[0081] In the coloring process of the optical fiber (10), the UV curing process may include an optical fiber surface curing process that determines the surface roughness of the coloring layer (14) of the optical fiber (10) and an optical fiber internal curing process that determines the bonding strength between the protective layer (13) and the coloring layer (14) within the optical fiber (10). Here, the optical fiber surface curing process and the optical fiber internal curing process may be performed simultaneously.

[0082] Specifically, the rollable optical fiber ribbon (100) according to the present invention may contain oxygen (O2) and nitrogen (N2) in the process atmosphere while performing the coloring process of each optical fiber (10).

[0083] Here, as the concentration of oxygen (O2) increases, the surface roughness of the optical fiber (10) formed after the coloring process increases, whereas as the concentration of nitrogen (N2) increases, the surface roughness of the optical fiber (10) formed after the coloring process may decrease.

[0084] The process atmosphere during the coloring process of each optical fiber (10) of the rollable optical fiber ribbon (100) according to the present invention may have a volume ratio of oxygen (O2) and nitrogen (N2) in the range of 1:4 to 1:9. In the case of a general optical fiber ribbon, the content of oxygen (O2) in the coloring process atmosphere is minimized to form the surface of the optical fiber as smooth as possible, but in the case of the rollable optical fiber ribbon (100) according to the present invention, the surface of the coloring layer (14) of the optical fiber (10) can be formed relatively rough by including oxygen (O2) in the coloring process atmosphere in an amount of about 10% to 25% of the volume of nitrogen (N2).

[0085] In addition, when performing the coloring process of each optical fiber (10), the coloring process atmosphere may be configured such that the concentration of oxygen (O2) calculated by [Formula 1] below is in the range of more than 3500 ppm and less than 20000 ppm.

[0086] [Formula 1]

[0087] Oxygen concentration (ppm) = residence time (s) X compressed air volume (L / s) X 0.21 (ratio of oxygen in the air)

[0088] In the above [Formula 1], the residence time (s) means the length (m) of each joint (20) / optical fiber line speed (mps).

[0089] In this way, when the concentration of oxygen (O2) in the coloring process atmosphere is in the range of more than 3500 ppm and less than 20000 ppm, the arithmetic mean roughness (Ra) of the surface of the coloring layer (14) of the optical fiber (10) formed therefrom is formed in the range of 0.15 micrometers (μm) to 0.48 micrometers (μm), thereby enabling implementation of optimal bonding strength.

[0090] If the concentration of the oxygen (O2) is 3500 ppm or less, the arithmetic mean roughness (Ra) of the surface of the coloring layer (14) of the optical fiber (10) after the coloring process may not be sufficiently rough, so that the bonding strength between the optical fiber (10) and the joint (20) may be insufficient. On the other hand, if the concentration of the oxygen (O2) is 20000 ppm or more, the bonding strength between the optical fiber (10) and the joint (20) excessively increases, so that the bonding strength between the coloring layer (14) and the joint (20) increases more than the bonding strength between the protective layer (13) and the coloring layer (14) within the optical fiber (10), and accordingly, there is a risk that the coloring layer (14) may be torn or damaged by the joint (20) when the optical fiber (10) is separated.

[0091] In addition, the rollable optical fiber ribbon (100) according to the present invention can control the surface roughness of the coloring layer (14) of the optical fiber (10) by controlling the UV curing process condition variables in the coloring process of each optical fiber (10).

[0092] Specifically, the optical fiber ribbon (100) according to the present invention can be smoothly controlled to have an arithmetic mean roughness (Ra) of the optical fiber (10) in a range of 0.15 micrometers (μm) to 0.48 micrometers (μm) by controlling the UV curing time in a process atmosphere in which the concentration of oxygen (O2) is greater than 3500 ppm and less than 20000 ppm inside the UV curing device during the coloring process of each optical fiber (10), the drawing flux of the optical fiber (10) is 1000 mpm to 2100 mpm (meters per minute), and the curing degree of the coloring layer (14) is controlled to be in the range of 80% to 95%.

[0093] Furthermore, in the rollable optical fiber ribbon (100) according to the present invention, a plurality of optical fibers (10) must be maintained in a mutually bonded state at a joint (20), and at the same time, in the process of separating each optical fiber (10) during branching of the optical fiber ribbon, a pair of optical fibers (10) bonded to each other by each joint (20) must be easily separated from each other. As a measure of the ease of separation, the vertical separation strength can be measured.

[0094] The rollable optical fiber ribbon (100) according to the present invention can be configured so that the vertical separation strength at each of the joints (20) is less than 20 gf so that the core separation of a pair of optical fibers (10) in the vertical direction can be easily performed, and in this case, the possibility of increased optical loss and damage to the coloring layer (14) of the optical fiber (10) during the separation operation of the optical fiber (10) can be minimized.

[0095] Figure 6 illustrates a separation strength measuring device for measuring the vertical separation strength at a joint of a rollable optical fiber ribbon according to the present invention.

[0096] FIG. 6 is a view showing a method for measuring the separation strength in the vertical direction with respect to the optical fiber length direction at each of a plurality of joints (20) of an optical fiber ribbon (100) according to the present invention. In order to measure the vertical separation strength, the ends of a pair of optical fibers (10) joined by a plurality of joints (20) intermittently arranged along the optical fiber length direction among the optical fiber ribbons (100) are branched, and then each end of the branched pair of optical fibers, which is 10 cm away from the joints (20), is respectively fixed to each grip unit (1200) provided on a pair of mounts (1100) that can be moved in the opposite direction of a separation strength measuring device (1000), and then each optical fiber of the pair of optical fibers (10) fixed to the pair of grip units (1200) is pulled in the opposite direction at a speed of about 500 mm / min to separate the pair of optical fibers (10), and the separation strength at each joint unit (20) is measured.

[0097] Specifically, the above separation strength test device (1000) can measure the size of the separation force required to separate one bonding area (20), i.e., the vertical separation strength (T) in one bonding area (20), using a sensor such as a load cell, during the process in which a pair of bonded optical fibers (10) constituting an optical fiber ribbon (100) are split and separated in the vertical direction.

[0098] The rollable optical fiber ribbon (100) according to the present invention can have a horizontal separation strength that is a separation force required at a joint (20) to completely fracture a pair of optical fibers (10) arranged adjacent to each other in a direction parallel to the longitudinal direction of the optical fibers (10) in the longitudinal direction. The horizontal separation strength of the joint (20) is proportional to the bonding strength of the joint (20).

[0099] In the process of manufacturing a multi-core optical cable having a rollable optical fiber ribbon (100) of the present invention, several manufacturing processes, such as a tubing process, an assembling process, and a cabling process, in which a plurality of optical fibers (10) constituting the optical fiber ribbon (100) are pulled by a mechanical external force in the longitudinal direction of the optical cable or optical fiber (10), are frequently performed, and in order to prevent the plurality of optical fibers (10) constituting the rollable optical fiber ribbon (100) from being separated in an unwanted situation under these manufacturing processes, a sufficiently large horizontal separation strength (B) is required for each of the bonding areas (20).

[0100] Accordingly, in order to prevent separation of a pair of optical fibers (10), the rollable optical fiber ribbon (100) according to the present invention can be configured such that the horizontal separation strength at each of the joints (20) is at least 100 gf greater, and in this case, the separation phenomenon between individual optical fibers (10) is prevented during the optical cable manufacturing process, thereby ensuring process stability.

[0101] Figure 7 illustrates a separation strength measuring device for measuring horizontal separation strength at a joint of a rollable optical fiber ribbon according to the present invention.

[0102] FIG. 7 is a view showing a method of measuring horizontal separation strength in a direction parallel to the length of an optical fiber at each of a plurality of joints (20) of an optical fiber ribbon (100) according to the present invention. To measure the horizontal separation strength, a pair of optical fibers (10) mutually joined through one joint (20) among the plurality of optical fibers (10) constituting the optical fiber ribbon (100) are separated from the optical fiber ribbon (100), and then, with one joint (20) interposed, the unnecessary core area of ​​the optical fibers is cut and removed, as shown in the enlarged drawing of FIG. 7.

[0103] Then, each end of a pair of optical fibers (10) spaced 10 cm apart from the joint (20) is fixed to each grip portion (1200) provided in the separation strength measuring device (1000), and then, in the process of pulling a pair of optical fibers (10) fixed to the pair of grip portions (1200) in the direction of the length of the optical fibers at a speed of about 500 mm / min, the horizontal separation strength (B), which is the force until one joint portion (20) breaks and the pair of optical fibers (10) are separated from each other, is measured.

[0104] The horizontal separation strength measuring device (1000) for measuring the separation strength illustrated in FIG. 7 is shown to be identical to the vertical separation strength measuring device for measuring the separation strength illustrated in FIG. 6, but is not limited thereto, and various shaped equipment capable of fixing the ends of a pair of optical fibers (10) and pulling them parallel in the direction of the length of the optical fibers may be used.

[0105] [Example]

[0106] Specimens of a rollable optical fiber ribbon (100) having the optical fiber surface roughness described in Table 1 below were manufactured. Here, the surface roughness of each specimen was measured by measuring the arithmetic mean roughness (Ra) of the coloring layer (14) provided on the outermost layer of the optical fiber (10) using a surface roughness measuring device according to standard JIS B0601 using a VK-X100 shape measuring laser microscope from KEYENCE.

[0107] The horizontal separation strength (B) and vertical separation strength (T) of the rollable optical fiber ribbon specimens having each optical fiber surface roughness (Ra) listed in Table 1 below were measured. The horizontal separation strength (B) and vertical separation strength (T) of each specimen were determined as the average of the separation strength peak values ​​measured at four consecutive joints (20) constituting each specimen using the aforementioned separation strength measuring device (1000) and separation strength measuring method, respectively.

[0108] In addition, if the horizontal separation strength (B) measured in each specimen exceeds 100 gf, it is evaluated as 'pass', and if it is less than 100 gf, it is evaluated as 'fail'. If the vertical separation strength (T) measured in each specimen is less than 20 gf, it is evaluated as 'pass', and if it is more than 20 gf, it is evaluated as 'fail', and these results are listed in Table 1.

[0109] Psalm 1234567 Surface roughness (Ra) [μm] 0.09 0.13 0.15 0.32 0.48 0.55 0.61 Horizontal separation strength (B) [gf] 64.5 193.13 120.16 319.24 527.84 609.45 65 1.35 Failed Failed Passed Passed Passed Passed Passed Vertical separation strength (T) [gf] 4.3 0 5.7 9 6.17 8.15 16.19 22.89 27.72 Passed Passed Passed Passed Passed Failed Passed

[0110] As shown in Table 1 above, it was confirmed that Specimens 1 and 2 were formed so that the surface roughness (Ra) of the coloring layer (14) of the optical fiber (10) was less than 0.15 micrometers (μm), so that the bonding strength between the optical fiber (10) and the joint (20) was insufficient, and accordingly, the horizontal separation strength was less than 100 gf, which was insufficient, and an unwanted separation phenomenon of the optical fiber (10) could occur. In addition, it was confirmed that Specimens 6 and 7 were formed so that the surface roughness (Ra) of the coloring layer (14) of the optical fiber (10) exceeded 0.48 micrometers (μm), so that the bonding strength between the optical fiber (10) and the joint (20) excessively increased, and accordingly, the vertical separation strength (T) increased to less than 20 gf, so that the coloring layer (14) of the optical fiber was damaged when the optical fiber (10) was separated. Figure 8 shows a state in which the coloring layer (14) is damaged during branching of the optical fiber (10) in Psalm 7.

[0111] On the other hand, in the samples 3 to 5, the surface roughness (Ra) of the coloring layer (14) of the optical fiber (10) was 0.15 micrometers (μm) to 0.48 micrometers (μm), so that the horizontal separation strength (B) and the vertical separation strength (T) were optimized, thereby maintaining sufficient bonding strength between the optical fiber (10) and the joint (20), and at the same time, it was confirmed that the optical fiber (10) was easily branched during the separation operation of the optical fiber (10) and that the coloring layer (14) was not damaged.

[0112] Furthermore, the present invention can further provide an optical cable (1000) including the aforementioned rollable optical fiber ribbon (100).

[0113] FIG. 9 illustrates a cross-sectional view of one embodiment of an optical cable (1000) including a rollable optical fiber ribbon (100) according to the present invention.

[0114] As illustrated in FIG. 9, an optical cable (1000) according to the present invention may be configured to include an optical unit (300) including a plurality of rolled optical fiber ribbons (100) formed by rolling a rollable optical fiber ribbon (100) having the aforementioned configuration in the width direction and a first assembly member (200) that accommodates the plurality of the rolled optical fiber ribbons (100), a cable core (C) formed by assembling the plurality of the optical units (300), and an outer jacket (500) that wraps the cable core (C).

[0115] Here, as described above, the surface roughness of the coloring layer (14) of the optical fiber (10) can be formed to be less than 0.15 micrometers (μm) to 0.48 micrometers (μm) so that the optical fibers (10) can be smoothly separated from each other without being damaged or broken when branching each rollable optical fiber ribbon (100) within the optical cable (1000) while maintaining a bonding state between adjacent optical fibers (10) even in a dried state.

[0116] In the embodiment illustrated in FIG. 9, the optical cable (1000) according to the present invention is illustrated as having six rolled optical fiber ribbons (100) forming one optical unit (300) and eight optical units (300) assembled to form a cable core (C) of the optical cable (1000). However, the number of rollable optical fiber ribbons (100) forming each optical unit (300) and the number of optical units (300) forming the cable core (C) may be increased or decreased depending on the specifications required for the optical cable (1000) or the overall outer diameter, etc.

[0117] The first assembly member (200) constituting the optical unit (300) may be composed of a loose tube, a binder yarn, a binder tape, etc., and is preferably composed of a loose tube whose shape can be changed. The first assembly member (200) can protect the optical fiber (10) constituting the rollable optical fiber ribbon (100) from external impacts and external environments such as twisting, compression, and temperature changes. In addition, a waterproofing material such as a jelly compound, a waterproofing powder, or a waterproofing yarn may be included in the empty space inside the first assembly member (200) constituting the optical unit (300).

[0118] The optical cable (1000) according to the present invention may be provided with a second assembly member (400) on the outer periphery of the cable core (C), and preferably, a waterproof tape layer may be wound transversely. The waterproof tape layer is made of a superabsorbent resin or the like, protects the optical unit (300), and performs a waterproof function of absorbing moisture that has penetrated into the optical cable (1000).

[0119] In addition, the optical cable (1000) according to the present invention may be provided with one or more notches (600) on the inside of the outer jacket (500), and when a plurality of notches (600) are provided, they may be provided at positions symmetrical to each other, and each notch (600) serves to improve workability by facilitating the stripping of the outer jacket (500) during the branching operation of the optical fiber ribbon. In addition, a rip cord (700) that can be used for the removal operation of the outer jacket (500) may be provided on the inside of each notch (600).

[0120] In addition, the optical cable (1000) according to the present invention may be provided with at least one pair of tensile members (800) embedded in the outer jacket (500) in the longitudinal direction of the optical cable (1000), and the tensile members (800) generate tensile force when deformation such as bending the optical cable (1000) is applied, thereby protecting the internal structure of the cable core (C).

[0121] In addition, the optical cable (1000) may include an identification means (900) such as a stripe or protrusion of a specific color on the surface of the outer jacket (800), and the identification means (900) may perform a function of identifying the position of the notch (600) or tension member (800) that is not visible from the outside of the optical cable (1000).

[0122] Here, when the position of the notch (600) is identified through the identification means (900), the thin portion in the outer circumferential direction of the outer jacket (500) that must be removed to access the cable core (C) can be recognized, so that the outer jacket (500) can be easily removed. At this time, when a part of the outer jacket (500) near the notch (600) is removed to access the rip cord (700), the outer jacket (500) can be removed more easily in the longitudinal direction of the optical cable (1000) using the rip cord (700).

[0123] In addition, if the location of the tension member (800) is identified through the identification means (900), the effort to find the location of the outer jacket (500) that must be removed to access the tension member (800) can be reduced.

[0124] 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. A plurality of optical fibers including a core; a cladding layer surrounding the core; a coating layer surrounding the cladding layer; and a coloring layer surrounding the coating layer; are arranged in parallel in the longitudinal direction, A plurality of joints for jointing adjacent pairs of optical fibers among the plurality of optical fibers; The above joints are intermittently arranged along the length direction of the optical fiber, The above joint is arranged in a certain area in the circumferential direction of the optical fiber, A rollable optical fiber ribbon characterized in that the arithmetic mean roughness (Ra) of the surface of the coloring layer according to the JIS B0601 standard is 0.15 micrometers (μm) to 0.48 micrometers (μm).

2. In paragraph 1, A rollable optical fiber ribbon, characterized in that the outer diameter of the clad layer is 80 micrometers (μm) to 125 micrometers (μm), and the thickness of the coloring layer is 3.0 micrometers (μm) to 10.0 micrometers (μm).

3. In paragraph 1, A rollable optical fiber ribbon characterized in that the above joint is formed by applying a jointing resin to the surface of the coloring layer of the optical fiber and then UV curing the resin.

4. In paragraph 1, The density of the above joint is 0.8 g / cm 3 1.4 g / cm 3 , Tensile strength is 2.0 MPa to 22 MPa, The rate of elongation is 40% to 210%, The elastic modulus is 5 MPa to 90 MPa at 2.5% strain and A rollable optical fiber ribbon characterized by a viscosity of 80 mPa·s to 800 mPa·s at 25°C.

5. In an optical cable including a rollable optical fiber ribbon of any one of claims 1 to 4, An optical unit comprising a plurality of rollable optical fiber ribbons; and a first assembly member accommodating the plurality of rollable optical fiber ribbons; a cable core comprising one or more of the above optical units; and An optical cable characterized by comprising an outer jacket wrapping the cable core.

6. In paragraph 5, An optical cable characterized in that the above cable core collects a plurality of optical units.

7. In paragraph 6, An optical cable characterized by including a second assembly member that wraps around the outer circumference of the cable core.

8. In paragraph 5, An optical cable characterized by having one or more notches arranged in the inner region of the outer jacket and an identification means capable of identifying the position of the notches.

9. In paragraph 8, An optical cable characterized in that it has a ripcord accommodated inside the notch.

10. In paragraph 5, An optical cable characterized in that at least one pair of tension members are embedded in the outer jacket in the longitudinal direction of the optical cable and an identification means capable of identifying the position of the tension members is provided.

11. A method for manufacturing an optical fiber for a rollable optical fiber ribbon comprising a plurality of optical fibers and a plurality of joints intermittently arranged along the length direction of the optical fibers, A step of drawing a bare fiber including a core and a cladding surrounding the core from a preform; A step of applying a coating material to form a coating layer on the optical fiber; A step of applying a coloring material after the step of applying the above coating material; and A step of UV curing at least one of the above coating material and the curling material; The above coloring material includes a resin mixed with coloring pigment particles, A method for manufacturing an optical fiber for a rollable optical fiber ribbon, characterized in that, in the step of forming the above-mentioned coloring layer, the atmosphere has an oxygen concentration in a range of more than 3500 ppm and less than 20000 ppm.

12. In paragraph 11, A method for manufacturing an optical fiber for a rollable optical fiber ribbon, characterized in that it further comprises a step of UV curing the coating material after the step of applying the coating material.

13. In paragraph 11, A method for manufacturing an optical fiber for a rollable optical fiber ribbon, characterized in that the volume ratio of oxygen and nitrogen in the atmosphere in the step of forming the coloring layer is in the range of 1:4 to 1:

9.

14. In paragraph 11, A method for manufacturing an optical fiber for a rollable optical fiber ribbon, characterized in that the optical fiber withdrawal speed during the above UV curing is 1000 mpm to 2100 mpm, the curing time is 0.03 seconds to 0.1 seconds, and the degree of curing of the coloring layer is in the range of 80% to 95%.

15. In paragraph 11, The coating layer includes a first coating layer that contacts and wraps the optical fiber; a second coating layer that contacts and wraps the colored layer, A method for manufacturing an optical fiber for a rollable optical fiber ribbon, characterized in that the modulus of the first coating layer is lower than the modulus of the second coating layer.

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