Optical fiber ribbon and slotless optical cable

Abstract

Disclosed is an optical fiber ribbon (1) in which a plurality of single-core coated optical fibers (11-22) are intermittently connected or separated in a length direction and a width direction while being connected every two cores. The optical fiber ribbon (1) satisfies conditional expressions [1], [2] when the length in the longitudinal direction of a connection portion (3) is denoted by A, the length in the longitudinal direction of a non-connection portion (5) in which separation portions (4) adjacent to each other overlap when viewing the separation portions (4) in the width direction is denoted by C, and the periodic interval in the longitudinal direction between the connection portions (3) is denoted by P.　[1]:P ≤ 150 mm [2]: A:C = 25-45 mm : 10-30 mm

Description

[Technical field]

[0001] The present invention relates to an optical fiber ribbon and a slotless optical cable. [Background technology]

[0002] In recent years, data traffic has increased dramatically due to the spread of IoT (Internet of Things), the full-scale commercial launch of 5G, and autonomous driving, among other factors, and this has led to a growing global demand for the development and construction of high-speed, high-capacity optical fiber communication networks to support this traffic. In particular, in Western countries, information and communication cables are often laid in underground ducts, and there are physical restrictions on the installation space inside the ducts. In order to economically realize the development and construction of high-speed, large-capacity optical fiber communication networks in Western countries, there is a strong demand to reduce installation costs by introducing cables with higher optical fiber core density than conventional cables while still using existing ducts.

[0003] Patent Document 1 discloses an optical cable using an intermittently connected optical fiber ribbon as an example of such a high-density optical cable. The technology of Patent Document 1 in particular aims to prevent malfunctions during fusion splicing of optical fiber ribbon core wires while suppressing deterioration of the transmission characteristics of the optical fiber by controlling the longitudinal length of the connection part, the length of the longitudinal overlapping part of the non-connection part between different optical fiber core wires, etc., to be constant (see paragraphs 0026-0027, Examples, Figure 1, etc.). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6657976 DISCLOSURE OF THEINVENTION [Problem to be solved by the invention]

[0005] Incidentally, in such high-density optical cables, when the optical fiber ribbons are gathered at high density and assembled into a cable, they are deformed and mounted in a folded manner. This deformation changes the overlap between connected parts and the twist of the non-connected parts depending on the length of the non-connected parts of the intermittent structure. It is known that these deformations within the optical fiber ribbon cable have a significant effect on the "bending distortion" of the optical fiber. The technology of Patent Document 1 simply evaluates the transmission characteristics due to transmission loss by using a 432-fiber optical fiber ribbon in a slotless optical cable (see Examples), and does not take into account the bending distortion characteristics assuming high-density mounting.

[0006] SUMMARY OF THE PRESENT EMBODIMENTS Accordingly, a primary object of the present invention is to provide an optical fiber ribbon capable of improving bending distortion characteristics, and a slotless optical cable using the same. [Means for solving the problem]

[0007] In order to solve the above problem, according to one aspect of the present invention, In an optical fiber ribbon in which a plurality of mono-coated optical fibers are connected in pairs and intermittently connected or separated in the length direction and width direction, The present invention provides an optical fiber ribbon that is characterized in that, when the longitudinal length of the connecting portion is A, the longitudinal length of the non-connecting portion where adjacent separation portions overlap when viewed in the width direction is C, and the longitudinal periodic interval of the connecting portions is P, the following conditional expressions (1) and (3) are satisfied. 140mm≦ P≦150mm (1) A=40~45mm and C=30mm (3)

[0008] According to another aspect of the present invention, The optical fiber ribbon described above, A winding method for fixing a plurality of the optical fiber ribbons; An outer jacket that covers the roll; A tension member installed in the outer sheath; a ripcord disposed in the jacket for tearing the jacket; A slotless optical cable is provided, comprising: Effect of the Invention

[0009] According to the present invention, the bending distortion characteristics can be improved. [Brief description of the drawings]

[0010] [Figure 1] FIG. 2 is a plan view showing a schematic configuration of an optical fiber ribbon. [Diagram 2] 2 is a cross-sectional view taken along line XX in FIG. 1. [Diagram 3] FIG. 1 is a cross-sectional view showing a schematic configuration of a slotless optical cable. [Figure 4] 1 is a diagram for explaining a method for measuring bending strain. [Diagram 5] 1 is a perspective view showing a schematic configuration of an optical fiber ribbon manufacturing apparatus. [Figure 6] FIG. 13 is a diagram showing a schematic configuration of an optical fiber ribbon manufacturing apparatus according to a modified example. [Figure 7] FIG. 7A is a side view showing the schematic configuration of a rotary blade of a separating die according to a modified example, FIG. 7B is a side view showing the schematic configuration of a rotary blade of a separating die according to a modified example, and FIG. 7C is a side view showing the schematic configuration of a rotary blade of a separating die according to a modified example. [Figure 8] 13 is a side view showing a schematic view of the rotation of a rotary blade according to a modified example. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, an optical fiber ribbon and a slotless optical cable according to preferred embodiments of the present invention will be described. In this specification, the lower limit and upper limit of a numerical range are included in the numerical range.

[0012] [Optical fiber ribbon] FIG. 1 is a plan view showing a schematic configuration of an optical fiber ribbon 1. As shown in FIG. 1, the optical fiber ribbon 1 has a plurality of mono-coated optical fibers 11-22 (12 in FIG. 1). Each mono-coated optical fiber 11-22 has a configuration in which an optical fiber strand is coated in order with a primary coating layer and a secondary coating layer. As shown in Fig. 2, a linking resin 2 for linking the single-coated optical fibers together is applied to the surface of the single-coated optical fibers 11-22, and the single-coated optical fibers 11-22 are intermittently linked or separated in the length and width directions while being linked in pairs as shown in Fig. 1. The linking resin 2 is preferably a photocurable resin having a viscosity of 4.7 to 8.8 Pa s at 25°C, and is an epoxy acrylate photocurable resin or a urethane acrylate photocurable resin.

[0013] 1, in the optical fiber ribbon 1, connecting portions 3 where the mono-coated optical fibers are connected and separation portions 4 where the mono-coated optical fibers are separated are intermittently formed. In the separation portions 4, non-connecting portions 5 are formed where adjacent separation portions 4 overlap each other when viewed in the width direction.

[0014] In such an optical fiber ribbon 1, when the longitudinal length of the connecting portion 3 is A, the longitudinal length of the separation portion 4 is B, the longitudinal length of the non-connecting portion 5 is C, and the longitudinal periodic interval of the connecting portion 3 is P, the optical fiber ribbon 1 satisfies the following conditional formulas (1) and (2), and preferably satisfies the following conditional formulas (1) and (3): P≦150mm (1) A:C=25~45mm:10~30mm... (2) A:C=40~45mm:30mm (3)

[0015] According to the optical fiber ribbon 1 described above, the ratio between the length A of the connecting portion 3 and the length C of the non-connecting portion is controlled to a constant value, and the bending distortion characteristics can be improved (see the following examples).

[0016] [Optical fiber ribbon manufacturing device and manufacturing method] (1) Optical fiber ribbon manufacturing equipment FIG. 5 is a diagram showing a schematic configuration of an optical fiber ribbon manufacturing apparatus 10. As shown in FIG. As shown in FIG. 5, in the optical fiber ribbon core manufacturing apparatus 10, a tape die 200, a separation die 300 and two light irradiation devices 400, 500 are mainly installed in this order along the conveying direction A of the single-coated optical fiber 100, and the single-coated optical fiber 100 passes between these dies and devices in this order.

[0017] The tape die 200 is a general-purpose die for collectively coating the periphery of multiple single-coated optical fibers 100 with photocurable resin, and applies uncured photocurable resin in a tape-like form to the multiple single-coated optical fibers 100 that pass through it, forming a tape layer 8.

[0018] A plurality of separation needles 320, 340, 360 that can be raised and lowered are installed on the separation die 300 (three in FIG. 5). Each of the separation needles 320, 340, 360 is disposed above the mono-coated optical fibers 100, and the separation needle 340 in the center and the separation needles 320, 360 on both sides rise and fall alternately relative to the uncured photocurable resin, thereby forming the separation portions 4 and the connection portions 3 intermittently. A resin suction device 380 for sucking up excess photocurable resin is installed on the separating die 300. The resin suction device 380 is configured to suck up excess photocurable resin that is blocked by the downward movement of the separating needles 320, 340, and 360.

[0019] The upstream light irradiation device 400 irradiates the uncured photocurable resin with light, semi-curing the photocurable resin. "Semi-cured" means that the resin is not completely cured, that is, the resin is partially cross-linked by light energy. The downstream light irradiation device 500 further irradiates the semi-cured photocurable resin with light, so as to completely cure the photocurable resin. "Completely cured" means that the resin is completely or nearly completely cured, that is, the resin is completely or nearly completely crosslinked by light energy. As for the upstream light irradiation device 400 and the downstream light irradiation device 500, the upstream light irradiation device 400 has a smaller integrated irradiation amount, whereas the downstream light irradiation device 500 has a larger integrated irradiation amount.

[0020] (2) Manufacturing method of optical fiber ribbon While multiple single-coated optical fibers 100 are transported along the transport direction A (the transport speed is preferably 60 to 300 m / min), first, uncured photocurable resin is applied in a tape shape to the multiple single-coated optical fibers 100 using a tape die 200 to form a tape layer 8. Thereafter, the separating needles 320 , 340 , 360 of the separating die 300 are raised and lowered relative to the tape layer 8 to form the separating portions 4 and the connecting portions 3 in the tape layer 8 . Thereafter, the tape layer 8 is irradiated with light by the light irradiation device 400 to semi-cure the uncured photocurable resin, and finally, the semi-cured photocurable resin is completely cured by further irradiating it with light by the light irradiation device 500. During these steps, the temperature of the tape die 200 is set higher than the temperature of the separating die 300.

[0021] [Variations] The separating die 60 in FIG. 6 may be applied instead of the separating die 300 in FIG. In the separating die 60 in Fig. 6, a plurality of rotary blades 62, 64, 66 (three in Fig. 6) are provided for the exit surface of the mono-coated optical fiber 100. Each of the rotary blades 62, 64, 66 rotates following the transport of the mono-coated optical fiber 100, and has the same rotation axis. As shown in Fig. 7A, a notch 64a is formed in the central rotary blade 64, and as shown in Fig. 7B, notches 62a, 66a are also formed in the rotary blades 62, 66 on both sides. As shown in Fig. 7C, the notch 64a of the central rotary blade 64 is out of phase with the notches 62a, 66a of the rotary blades 62, 66 on both sides. As shown in Figure 8, when each of the rotary blades 62, 64, 66 rotates in accordance with the transport of the single-coated optical fiber 100, the notch 64a of the central rotary blade 64 and the notches 62a, 66a of the rotary blades 62, 66 on both sides rotate with a phase shift, so that separation sections 4 and connection sections 3 are formed alternately.

[0022] [Slotless optical cable] FIG. 3 is a cross-sectional view showing a schematic configuration of a slotless optical cable 30 using the optical fiber ribbon 1. As shown in FIG. In the slotless optical cable 30, a plurality of optical fiber ribbons 1 are bundled and twisted together, and this is fixed with a pressure winding 32. For example, six optical fiber ribbons 1 each having 12 cores are bundled together and these six are twisted together, and the twisted body is fixed with a pressure winding 32. The pressure winding 32 is preferably made of a water-absorbent nonwoven fabric, and specifically, a water-absorbent polymer is laminated on the nonwoven fabric. Polyethylene resin or the like is extruded onto the winding 32, which is covered with an outer sheath 34. Two tension members 36 are installed on the top and bottom of the outer sheath 34, and one rip cord 38 for tearing the outer sheath 34 is also installed on each of the left and right sides.

[0023] According to the above slotless optical cable 30, the tension members 36 are installed at the top and bottom in Fig. 3, so flexibility in the left-right direction is ensured, and workability can be improved when laying the cable inside a duct. The rip cord 38 is also installed at a symmetrical position (180 degrees diagonally) in Fig. 3, so the jacket 34 can be easily peeled into two equal parts, improving workability when processing the cable terminal or when branching the cable midway. EXAMPLES

[0024] [Example 1] (1) Preparation of samples The single-core coated optical fiber used was a 250 μm outer diameter single-core coated optical fiber with a primary coating made of a urethane acrylate-based photocurable resin with a Young's modulus of approximately 5 MPa at 23°C on a quartz glass-based SM optical fiber with an outer diameter of 125 μm, and a secondary coating made of a urethane acrylate-based photocurable resin with a Young's modulus of approximately 700 MPa at 23°C. Then, 12 single-coated optical fibers were aligned and a urethane acrylate photocurable resin (with a viscosity of 5.2±0.5 Pa·s before curing at 25°C and a Young's modulus of 550 MPa after curing) was used to produce Sample 1-6 of optical fiber ribbon wire in which the parameters of the longitudinal length A of the connecting portion, the longitudinal length C of the non-connecting portion, and the longitudinal periodic interval P of the connecting portion were varied.

[0025] (2) Sample evaluation: Measurement of bending strain Using the optical fiber ribbon sample 1-6, the slotless optical cable sample 1-6 in Figure 3 was manufactured. Specifically, six samples of 12-core optical fiber ribbon were prepared and bound with a bundle tape to form a 72-core unit. After that, six of the 72-core units were twisted together, pressed and fixed with absorbent nonwoven fabric, and coated with polyethylene by extrusion and then with an outer jacket to manufacture the 432-core slotless optical cable sample 1-6. Then, 30 m of each of the slotless optical cable samples 1-6 was cut out, one end of which was connected to a distortion measuring device (OPTICAL BACKSCATTER REFLECTOMETER Model OBR4600) manufactured by Luna Technology, and the other end was opened. The middle of each cut out piece was bent at a certain angle. The cable was looped three times at a radius (15 times the outer diameter of the cable) and the bending strain was measured using OFDR (optical frequency domain analysis) (see Figure 4). The measurement results are shown in Table 1. In Table 1, "◎" indicates a measured value of 0.05% or less, "○" indicates a measured value of more than 0.05% but less than 0.1%, and "×" indicates a measured value of more than 0.1%. If the measurement result is ◎ or ○, the product can be used in practical applications.

[0026] [Table 1]

[0027] (3) Summary As shown in Table 1, it is evident that controlling the ratio of the length A of the connecting portion to the length C of the non-connecting portion to a constant value is useful in improving bending strain.

[0028] [Example 2] The transmission characteristics, mechanical characteristics, and temperature characteristics of the slotless optical cable sample 4 were evaluated, and the results shown in Table 2 were obtained, with good results being obtained for all characteristics.

[0029] [Table 2]

[0030] This application claims priority based on Japanese Patent Application No. 2021-212640, filed on December 27, 2021. The contents of the specification and drawings of that application are incorporated herein by reference in their entirety. [Industrial Applicability]

[0031] The present invention relates to an optical fiber ribbon and a slotless type optical cable, and is particularly useful for improving bending strain characteristics. [Explanation of symbols]

[0032] 1 Optical fiber ribbon 2. Interlocking Resin 3 Connecting part 4 Separation section 5 Unconnected part 8 Tape Layers 11-22 Single-Coated Optical Fiber 30 Slotless optical cable 32 Osamaki 34 Outer cover 36 Tension member 38 Ripcord 60 Separation Dice 62, 64, 66 Rotary blade 62a, 64a, 66a Notch 100 Single-core coated optical fiber 200 Tape Dice 60, 300 Separate Dice 320, 340, 360 Separation Needle 380 Resin suction device 400 (Upstream) Light Irradiation Device 500 (Downstream) Light Irradiation Device

Claims

1. In an optical fiber ribbon in which a plurality of mono-coated optical fibers are intermittently connected or separated in the length direction and the width direction in a state where the optical fibers are connected in pairs, An optical fiber ribbon characterized in that, when the longitudinal length of the connection portion is A, the longitudinal length of the non-connection portion where adjacent separation portions overlap when viewed in the width direction is C, and the longitudinal periodic interval of the connection portions is P, the following conditional expressions (1) and (3) are satisfied: 140 mm≦P≦150 mm … (1) A = 40 to 45 mm and C = 30 mm ... (3)

2. The optical fiber ribbon according to claim 1 , A winding method for fixing a plurality of the optical fiber ribbons; An outer jacket that covers the roll; A tension member installed in the outer sheath; a ripcord disposed in the jacket for tearing the jacket; A slotless optical cable comprising:

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