TW202334680A - Optical fiber assembly, optical fiber cable, and method for manufacturing optical fiber assembly - Google Patents

Abstract

This optical fiber assembly comprises a plurality of optical fibers, and a plurality of intermittently fixed optical fiber ribbons including a plurality of fixing portions for intermittently fixing the plurality of optical fibers in the longitudinal direction thereof. The position in the longitudinal direction of a reversal portion and the position in the longitudinal direction of a switching portion in which the change of direction of a vector sum is switched are displaced from each other.

Description

Optical fiber assembly, optical fiber cable, and manufacturing method of optical fiber assembly

The present invention relates to an optical fiber assembly, an optical fiber cable, and a manufacturing method of the optical fiber assembly. This invention claims priority based on Japanese Patent Application No. 2021-212159 filed in Japan on December 27, 2021, the contents of which are incorporated herein by reference.

Patent Document 1 discloses a technology that prevents SZ reverse twisting by twisting a plurality of second optical fiber ribbon cores in one direction on a plurality of SZ-twisted first optical fiber ribbon cores. Prior technical literature patent documents

Patent Document 1: Japanese Patent Application Publication No. 2014-106380

The problem to be solved by the invention

After careful review, the inventor of this case found that when a plurality of optical fiber ribbon core wires are subjected to SZ twisting, the optical fiber ribbon core wire is twisted around its own center of gravity, and the twisting direction is along the long side. Switch in direction. In addition, it was found that there is a possibility that at the position where the twist direction is switched, the force to release the twist becomes larger, which may cause a phenomenon in which the SZ twists of the optical fiber ribbon core wires are reversed (so-called anti-twist). When reverse twist occurs, the transmission loss of the optical fiber cable increases when it is bent.

The present invention was made in consideration of such circumstances, and an object thereof is to provide an optical fiber assembly and an optical fiber cable that can suppress reverse twist. means to solve problems

In order to solve the above problems, an optical fiber assembly according to one aspect of the present invention includes a plurality of intermittently fixed core wires, and the plurality of intermittently fixed core wires include a plurality of optical fibers and a plurality of the plurality of optical fibers intermittently fixed in the longitudinal direction. The fixing portion, the optical fiber assembly has an SZ twist structure, the SZ twist structure is such that a cycle including a forward twist portion and a counter twist portion repeats in the longitudinal direction, and the forward twist portion is the plurality of the aforementioned plurality of intermittently fixed portions. The core wires are twisted, and the counter-twisting part is the plurality of intermittently fixed core wires twisted in the opposite direction to the forward twisting part, and the plurality of intermittently fixed core wires are twisted in a cross section perpendicular to the longitudinal direction. Let the midpoint of the two aforementioned optical fibers at both ends of one of the intermittent fixed core wires be M, let the center of gravity be G, and let the vector starting from the aforementioned midpoint M and ending with the aforementioned center of gravity G be MG. , when the vector obtained by synthesizing the vector MG for all of the plurality of intermittently fixed core wires is taken as a vector sum, the position in the longitudinal direction of the reverse part where the forward twist part and the reverse twist part are switched , and a switching unit that switches the change in the direction of the vector sum, the positions in the longitudinal direction are shifted.

Furthermore, a method for manufacturing an optical fiber assembly according to one aspect of the present invention is a method for manufacturing an optical fiber assembly, wherein the optical fiber assembly is provided with a plurality of intermittently fixed core wires, and the plurality of intermittently fixed core wires include a plurality of and a plurality of fixing portions for intermittently fixing the plurality of optical fibers in the longitudinal direction. The optical fiber assembly has an SZ twist structure. The SZ twist structure is a periodic structure including a forward twist portion and a counter twist portion. Repeating in the longitudinal direction, the forward twisting part is the plurality of intermittent fixed core wires twisted together, and the reverse twisting part is the plurality of intermittent fixed core wires twisted in the opposite direction to the forward twisting part. In the cross-section perpendicular to the aforementioned long side direction, let the midpoint of the two aforementioned optical fibers located at both ends of one of the aforementioned plurality of intermittent fixed cored cords be M, and let the center of gravity be G. When the vector in which the midpoint M is the starting point and the center of gravity G is the end point is MG, and the vector obtained by synthesizing the vector MG for all of the plurality of intermittently fixed core wires is a vector sum, the forward twisting portion The position in the longitudinal direction of the reversing portion that switches the reverse twist portion, and the position in the longitudinal direction of the switching portion that switches the direction of the vector sum are shifted. Invention effect

According to the above aspect of the present invention, it is possible to provide an optical fiber assembly and an optical fiber cable that can suppress reverse twist.

Hereinafter, the optical fiber assembly 1 and the optical fiber cable 100 according to the embodiment of the present invention will be described based on the drawings. As shown in FIG. 1 , the optical fiber cable 100 of this embodiment includes an optical fiber assembly 1 including a plurality of optical fiber units U. As shown in FIG. 2 , each optical fiber unit U has a plurality of intermittently fixed core wires 10 . In other words, a plurality of intermittent fixed core wires 10 constitute a plurality of optical fiber units U. In addition, each intermittently fixed core wire 10 includes a plurality of optical fibers 11 . In other words, a plurality of optical fibers 11 constitute a plurality of intermittent fixed core wires 10 . The outer diameter of each optical fiber 11 is, for example, 250 μm. However, the outer diameter of the optical fiber 11 may also be 200 μm or other values.

(direction definition) Here, in this embodiment, the longitudinal direction of the optical fiber assembly 1 (optical fiber cable 100) is simply called the longitudinal direction Z. The longitudinal direction Z is also a direction parallel to the central axis O of the optical fiber assembly 1 (optical fiber cable 100). A direction along the long side direction Z is called the +Z direction or the front. The direction opposite to the +Z direction is called the -Z direction or rear. The section perpendicular to the longitudinal direction Z is called a transverse section. Viewing the cross section from the long side direction Z is called the cross section perspective. The direction orthogonal to the central axis O of the optical fiber assembly 1 (optical fiber cable 100) is called a radial direction. Along the radial direction, the direction approaching the central axis O is called the radial inner side, and the direction away from the central axis O is called the radial outer side. Viewed from the long side direction Z, the direction surrounding the central axis O is called the circumferential direction.

As shown in FIG. 1 , the optical fiber cable 100 of this embodiment is a so-called slotless optical fiber. That is, the optical fiber cable 100 of this embodiment does not have a groove rod forming a groove (groove) for accommodating the optical fiber 11 (the intermittently fixed core wire 10). However, the optical fiber cable 100 may also be a grooved optical fiber with a grooved rod. In this case, the optical fiber assembly 1 of this embodiment can also be accommodated in the groove of the optical fiber cable 100 .

As shown in FIG. 1 , the optical fiber cable 100 of this embodiment includes the above-mentioned optical fiber assembly 1 , a crimping member 120 covering the optical fiber assembly 1 , and an outer shell that covers and accommodates the optical fiber assembly 1 via the crimping member 120 . Quilt piece 110. That is, the optical fiber assembly 1 can be regarded as a portion of the optical fiber cable 100 excluding the jacket member 110 and the crimping member 120 . In addition, the optical fiber assembly 1 and the crimped material 120 may be collectively referred to as a core material.

The crimping member 120 is a strip-shaped member and bundles a plurality of optical fiber units U. As long as the optical fiber unit U can be bundled, the type of the crimping member 120 is not particularly limited. For example, non-woven fabric or polyester tape may be used as the crimping member 120 . The crimped member 120 may also be water absorbent. The rolling member 120 may also wind the optical fiber assembly 1 longitudinally or transversely. For example, when the crimping member 120 is an adhesive tape extending in the longitudinal direction Z, the crimping member 120 may also be formed in a cylindrical shape covering the optical fiber unit U. In this case, both ends of the crimping member 120 in the circumferential direction may also overlap each other to form a covering portion. In addition, the crimping member 120 may not be in the shape of a strip, but may be a pipe forming body covering the optical fiber unit U. Since the optical fiber unit U is covered by the crimping member 120 in the longitudinal direction Z, the optical fiber 11 can be protected. In addition, there may be a position in the longitudinal direction Z where the optical fiber 11 is not covered by the crimping member 120 , and the optical fiber cable 100 may not have the crimping member 120 .

As the material of the outer cover 110, polyethylene (PE), polypropylene (PP), ethylene ethyl acrylate copolymer (EEA), ethylene vinyl acetate copolymer (EVA), ethylene propylene copolymer (EP), etc. can be used. Polyolefin (PO) resin, polyvinyl chloride (PVC), etc. In addition, the outer cover material 110 may be formed using a mixture (alloy, mixture) of the above-mentioned resins. In addition, depending on the purpose, various additives may be added to the outer quilt 110 . Examples of additives include flame retardants, colorants, deterioration inhibitors, inorganic fillers, and the like. In addition, the outer cover 110 may also have a two-layer structure or other multi-layer structure. For example, in the example shown in the figure, a protective layer covering the outer quilt 110 (the first outer quilt) may be provided on the outside, and a second outer covering covering the protective layer may be provided on the outside of the protective layer. Quilt pieces. The protective layer may also be made of metal or fiber-reinforced plastic (FRP), for example. Alternatively, the outer quilt 110 may not have a protective layer, but may only be formed by a plurality of layers of outer quilts.

In addition to the protrusion 110a described below, the outer shape of the quilt 110 in this embodiment is generally circular in cross-sectional view. However, the shape of the outer cover 110 can be appropriately changed. As shown in FIG. 1 , in this embodiment, a plurality of (four in the illustrated example) tensile members 130 and a pair of tear cords 140 are arranged in the quilt 110 .

The tensile body 130 is a member having a higher spring constant or tensile strength in the longitudinal direction Z than the outer cover 110 . For example, a metal wire (steel wire, etc.), a material in which metal wires are bundled, glass fiber, a material in which glass fiber is bundled, or the like can be used as the material of the tensile body 130 . Alternatively, fiber reinforced plastic (FRP) or the like may also be used as the tensile body 130 . When tension is applied to the optical fiber assembly 1 (optical fiber cable 100 ) along the longitudinal direction Z, the tension-resistant body 130 has a function of withstanding the tension and protecting the optical fiber 11 . A plurality of tensile bodies 130 are arranged on the outer quilt 110 . The plurality of tensile bodies 130 in this embodiment are arranged so as to sandwich the optical fiber assembly 1 in the radial direction. However, a plurality of tensile members 130 may also be isotropically arranged on the outer cover member 110 to surround the optical fiber assembly 1 (core material). In addition, the tensile body 130 does not need to be embedded in the outer quilt. For example, the tensile member 130 may be included in the center or core material of the optical fiber assembly 1 . Alternatively, depending on the use of the optical fiber cable 100, the optical fiber cable 100 may not have the tensile member 130.

The tear cord 140 is a member used to tear the outer quilt 110 apart. As the material of the tear cord 140, for example, synthetic fiber (polyester, etc.) threads, polypropylene (PP), or nylon cylindrical rods can be used. The tear cord 140 is arranged on the outer quilt 110 . In addition, from a cross-sectional view, the tear cord 140 may also be configured to be entirely embedded in the outer quilt 110 , or may be configured to partially be exposed from the outer peripheral surface or the inner peripheral surface of the outer quilt 110 . In one embodiment of the present invention, a pair of tear cords 140 is disposed so as to sandwich the optical fiber assembly 1 in the radial direction. In addition, in the circumferential direction, the positions of the tensile members 130 and the tear cords 140 are staggered from each other. In addition, the number of tear cords 140 may be one, or three or more. In addition, the tear cord 140 does not need to be embedded in the outer quilt 110 . For example, the tear cord 140 can also be attached to the optical fiber assembly 1 in the longitudinal direction. Alternatively, the fiber optic cable 100 may not have the tear cord 140 .

In the outer quilt 110 of this embodiment, a pair of protrusions 110a protruding radially outward from the outer peripheral surface of the outer quilt 110 are provided. The position of the protrusion 110a in the circumferential direction corresponds to the position of the tear cord 140. The protrusion 110a serves as a mark that allows the user to easily identify the position of the tear cord 140 from the outside of the optical fiber cable 100. In addition, the outer quilt 110 may not have the protrusion 110a. In this case, the protrusions 110a may also be replaced by linear coloring of the outer quilt 110. However, the outer quilt 110 may not have the protrusions 110a, and the outer quilt 110 may not be colored.

As described above, the optical fiber assembly 1 has a plurality of (12 in the example shown in FIG. 1 ) optical fiber units U. As shown in FIG. 1 , the optical fiber assembly 1 including the plurality of optical fiber units U according to this embodiment has a two-layer structure. That is, the plurality of optical fiber units U include a plurality (9 in the example shown) of outer units Uout and a plurality (3 in the example shown) of inner units Uin. Each outer layer unit Uout is located on the outer periphery of the optical fiber assembly 1 . The plurality of inner-layer units Uin are surrounded by the plurality of outer-layer units Uout from the outside in the radial direction. That is, the plurality of inner layer units Uin are located at the center of the optical fiber assembly 1 in a cross-sectional view. However, the number of inner-layer units Uin and the number of outer-layer units Uout can be changed appropriately. In addition, the optical fiber assembly 1 does not need to have a two-layer structure.

As shown in FIG. 2 , the optical fiber unit U of this embodiment includes the above-mentioned plurality of intermittently fixed core wires 10 and a bundle material 20 that bundles the plurality of intermittently fixed core wires 10 . The intermittent fixed tape included in one optical fiber unit U The number of core wires 10 may be two or more, for example, six.

The bundle material 20 is a member capable of bundling a plurality of intermittently fixed tape core wires 10 . For example, a linear, rope-shaped, or belt-shaped member can be used as the bundle member 20 . In this embodiment, the intermittently fixed tape core wire 10 is wound and bundled by the bundling material 20 . However, the structure in which the bundle material 20 bundles the intermittent fixing tape core wire 10 is not limited to the example shown in the figure. For example, the bundle material 20 may be spirally wound around the intermittently fixed tape core wire 10 . Alternatively, the optical fiber unit U may not have the bundle material 20 . In this case, for example, the intermittent fixed core wires 10 may be bundled by twisting a plurality of the intermittently fixed core wires 10 in the optical fiber unit U.

In addition, the optical fiber assembly 1 does not need to have the optical fiber unit U. In other words, the plurality of intermittently fixed core wires 10 may not constitute the optical fiber unit U. That is, the optical fiber assembly 1 may have a structure in which the crimping member 120 or the outer covering member 110 directly covers the intermittently fixed core wire 10 . In the example shown in FIG. 1 , the inner unit Uin is formed in a fan shape, and the outer unit Uout is formed in a quadrangular shape. The cross-sectional shape of the optical fiber unit U may be circular, elliptical, or polygonal without being limited to the illustrated example. Moreover, even if the optical fiber 11 is bundled by the bundle material 20, it will move appropriately to an empty space inside the cover material 110 while deforming the bundle material 20. Therefore, for example, as shown in FIG. 5 , the cross-sectional shape of the optical fiber unit U may also be curved.

As shown in FIG. 3 , each intermittently fixed tape core wire 10 includes a plurality of (12 in the illustrated example) optical fibers 11 and a plurality of fixing parts 12 . Each optical fiber 11 has a core material and a cladding material. A coating layer such as resin is provided on the outer periphery of the coating material. In the state before forming the optical fiber assembly 1, the plurality of optical fibers 11 in the intermittently fixed core wire 10 are arranged in a row. Thereby, the intermittently fixed core wire 10 has a strip-like shape. Hereinafter, for easier explanation, the direction in which the optical fibers 11 are arranged in the intermittently fixed tape core wire 10 may be referred to as the tape width direction W.

Each fixing part 12 fixes two adjacent optical fibers 11 in the tape width direction W to each other. A gap may be provided between two adjacent optical fibers 11 . In this case, the plurality of fixing portions 12 are intermittently arranged in the gap in the longitudinal direction Z. Alternatively, there may be no gap between two adjacent optical fibers 11 . Alternatively, two optical fibers 11 may be continuously fixed in the longitudinal direction Z to form an optical fiber group, and a plurality of optical fiber groups may be intermittently fixed by a plurality of fixing parts 12 . As shown in FIG. 3 , the plurality of fixing portions 12 are intermittently arranged two-dimensionally in the longitudinal direction Z and the belt width direction W. In addition, the arrangement of the fixing part 12 is not limited to the example of FIG. 3, and may be changed suitably. In addition, the arrangement pattern of the fixed portion 12 may not be a fixed pattern in the longitudinal direction Z or the belt width direction W. The arrangement pattern of the fixing portion 12 may not be a fixed pattern between different intermittently fixed core wires 10 . For example, UV curable resin may be used as the material of the fixing part 12 . However, as long as adjacent optical fibers can be fixed, the material of the fixing portion 12 is not particularly limited and can be appropriately changed.

As shown in FIG. 4 , in the optical fiber assembly 1 , a plurality of optical fiber units U and a plurality of intermittently fixed tape core wires 10 included in the optical fiber units U are twisted into an SZ shape. More specifically, the optical fiber assembly 1 has an SZ twisted structure in which the period 30 including the forward twist portion 31 and the reverse twist portion 32 repeats in the longitudinal direction Z. Period 30 is also called the twist pitch. In this specification, the length of the period 30 in the longitudinal direction is represented by P. In each of the forward twisting part 31 and the reverse twisting part 32, a plurality of optical fiber units U and a plurality of intermittent fixed tape core wires 10 included in the optical fiber units U are twisted with each other.

More specifically, in each of the forward twist portion 31 and the reverse twist portion 32 , each optical fiber unit U (the intermittently fixed core wire 10 ) is wound around the central axis O of the optical fiber assembly 1 . As shown in FIG. 4 , the direction in which the optical fiber assembly 1 is twisted in the forward twisting section 31 and the direction in which the optical fiber assembly 1 is twisted in the reverse twisting section 32 are opposite to each other. In addition, in the forward twist part 31 and the reverse twist part 32, the twist angle (winding angle) of the inner layer unit Uin and the twist angle (winding angle) of the outer layer unit Uout may be equal to or different from each other. In this specification, the position in the longitudinal direction where the forward twist portion 31 and the reverse twist portion 32 of the SZ twist structure are switched is referred to as the "reversal portion B". For one period 30 (dimension P in the longitudinal direction) in the SZ twist structure, two inversion portions B appear.

As shown in FIG. 5 , in the optical fiber assembly 1 of this embodiment, a plurality of intermittently fixed core wires 10 are laminated in a state of being crepe-curved in a cross-sectional view. In FIG. 5 , the optical fibers 11 belonging to the same intermittently fixed core wire 10 are connected by solid lines. In addition, the "bent state" refers to a state in which at least one intermittently fixed tape core wire 10 included in the optical fiber assembly 1 is bent.

In this specification, in order to evaluate the crepe state of the intermittently fixed tape core wire 10, the vector MG defined as follows is introduced. Here, FIG. 6 is a diagram depicting a cross-sectional view of the optical fiber assembly 1 (optical fiber unit U) shown in FIG. 5 on the xy plane. In FIG. 6 , the six intermittent fixed tape core wires 10 included in the optical fiber unit U are respectively referred to as the first to sixth tapes.

The vector MG is a vector quantity defined for each intermittently fixed cored wire 10 at each position in the longitudinal direction Z of the optical fiber assembly 1 . In the cross section, let the midpoint of two optical fibers 11 located at both ends of the optical fibers 11 constituting the intermittently fixed cored wire 10 be M, and the center of gravity of the intermittently fixed cored wire 10 be G. As shown in Figure 6, vector MG is a vector with the midpoint M as the starting point and the center of gravity G as the end point. In FIG. 6 , the vector MG defined for the first band is called vector MG1, and the vector MG defined for the second band is called vector MG2. The same goes for belts 3 to 6. In addition, it is extremely rare that the midpoint M coincides with the center of gravity G in a state where the intermittent fixed belt core wire 10 is creped (bent).

Here, in this specification, vector and MGtotal are defined as follows. The vector sum MGtotal refers to a vector obtained by combining the vectors MG of all the intermittently fixed core wires 10 included in the optical fiber assembly 1 . In FIG. 7 , the vector of each intermittently fixed core wire 10 is represented as MGn. By combining these vectors MGn, the vector sum MGtotal can be obtained. In addition, as shown in FIG. 7 , the angle formed by the vector sum MGtotal with respect to the Y-axis is called the phase φ of the vector sum. [Example]

Hereinafter, the phase φ of the vector sum will be described using a specific embodiment. In addition, the present invention is not limited to the following examples.

(Example 1) An optical fiber assembly 1 having three inner units Uin and nine outer units Uout is prepared. The inner unit Uin and the outer unit Uout respectively bundle six intermittently fixed core wires 10 with bundle materials. Each intermittent fixed core wire 10 has 12 optical fibers 11 respectively. That is, the optical fiber assembly 1 in Example 1 has a total of 864 optical fibers 11. The outer diameter of each optical fiber 11 is set to 250 μm. The optical fiber assembly 1 is covered with the crimping member 120 and further covered with the outer covering member 110 to produce the optical fiber cable 100 . The outer diameter of the outer quilt 110 is set to 18.2 mm, and the inner diameter of the outer quilt 110 is set to 11.5 mm. The thickness of the rolled member 120 is set to 0.2 mm. The outer diameter of the optical fiber assembly 1 is approximately 11.1 mm.

The optical fiber cable 100 is cut at equal intervals in the longitudinal direction to obtain a total of nine transverse sections. More specifically, the optical fiber cable 100 is cut at P/8. After cutting in this way, the optical fiber assembly 1 is fixed with epoxy resin, the fixed optical fiber assembly 1 is polished to make the cross section clear, and an image of the cross section is photographed with a microscope. On the image obtained by the microscope, the position of each optical fiber 11 is drawn on the xy plane. Alternatively, after fixing the optical fiber assembly 1 with epoxy resin, the optical fiber cable 100 may be cut at each position in the longitudinal direction. In this case, for example, the epoxy resin can be filled into the outer covering member 110 by injecting epoxy resin from one end in the longitudinal direction of the optical fiber cable 100 and sucking the epoxy resin from the other end. within.

For each cross section obtained by cutting, the phase of the SZ twist and the phase φ of the aforementioned vector sum can be obtained, and are plotted as shown in Figure 8. The phase of the SZ twist may also be the angle at which each optical fiber unit U (intermittent fixed core wire 10 ) is wound around the central axis O of the optical fiber assembly 1 . The horizontal axis in Fig. 8 represents the position in the longitudinal direction. For example, between the horizontal axis "0.1" and "0.2", there is a distance of 0.1P in the long side direction. In addition, based on the drawing of the phase of the SZ twist, the sinusoidal curve that is an approximate curve is marked with a solid line, and the position in the longitudinal direction where the sinusoidal curve becomes the minimum is designated as X. Similarly, based on the drawing of the phase φ of the vector sum, the sinusoidal curve that becomes the approximate curve is marked with a dotted line, and the position in the long side direction where the sinusoidal curve becomes the minimum is designated as Y. The best approximate curve (sinusoidal curve) can be found using, for example, the least squares method. The specific value of the phase φ of the vector sum can also be obtained from the gradient formula of this approximate curve.

As shown in FIG. 8 , the reason why the phase φ of the vector sum changes in a substantially sinusoidal manner in the longitudinal direction is because the crepe state of the cross-sectional shape of the intermittently fixed core wire 10 adapts to the SZ twist. This is explained in more detail below.

After SZ twisting of the intermittent fixed belt core wires 10, the position of each intermittent fixed belt core wire 10 in the circumferential direction changes so as to swing around the central axis O. At the same time, when viewed from a macro perspective, each of the intermittent fixed tape core wires 10 is mostly twisted around its own center of gravity. Conceptually, since the former is similar to "revolution" and the latter is similar to "rotation", they are called "revolution" and "rotation" respectively in this specification.

Regarding "rotation", each intermittent fixed core wire 10 does not continue to twist in a single direction, but the twisting direction switches at predetermined intervals in the longitudinal direction. In this way, the position in the longitudinal direction where the twist direction of the intermittently fixed core wire 10 is switched can be regarded as the position Y shown in FIG. 8 . On the other hand, the position X in the longitudinal direction is the position itself of the inversion portion B. That is, the forward twisting part 31 and the reverse twisting part 32 are switched with the position X as a boundary, and the twisting direction of each intermittently fixed core wire 10 is switched with the position Y as a boundary.

When the SZ twist is performed on the intermittently fixed core wire 10, the force for reverse twisting at the reversing portion B becomes larger. Similarly, when the intermittently fixed core wire 10 is twisted, the force required to release the twist becomes larger in the portion where the twisting direction is switched (switching portion). The "force to release the twist" directed at the latter also acts as a force to reverse the SZ twist. Here, in this embodiment, the position X and the position Y are offset in the longitudinal direction. In other words, the point (position X) where the counter-twist force due to "revolution" becomes maximum and the point (position Y) where the counter-twist force due to "rotation" becomes maximum are shifted in the longitudinal direction. This can prevent the two forces from becoming maximum at one point, and can reduce the maximum value of the reverse twist force acting on the entire optical fiber assembly 1 . Therefore, the occurrence of the phenomenon in which the SZ twist is released (reverse twist) can be suppressed.

Table 1 is the result of examining how far position X and position Y should be staggered.

[Table 1]

The "judgment" shown in Table 1 shows the magnitude of the risk of reverse twist to SZ twist. When it is judged as "C", it means that reverse twist is likely to occur. When it is judged as "B", it means that it is difficult to produce reverse twist. When it is judged as "A", it means that the risk of reverse twist is significantly smaller. As shown in Table 1, by setting the distance in the longitudinal direction between position X and position Y to be P/128 or more, the anti-twist suppression effect can be expected. In addition, by setting the distance in the longitudinal direction between position X and position Y to be P/64 or more, the anti-twist suppression effect can be further increased.

(Example 2) In Example 1, each intermittently fixed tape core wire 10 is bundled with a bundle material 20, and the optical fiber assembly 1 is further divided into an inner layer and an outer layer. In Example 2, the intermittently fixed tape core wire 10 is not bundled with the bundle material 20 and is not arranged into an inner layer and an outer layer, but is subjected to SZ twisting. The number of intermittently fixed core wires 10 included in the optical fiber assembly 1 is 24, and the number of optical fibers 11 included in each intermittently fixed core wire 10 is 12. That is, the optical fiber assembly 1 of Example 2 has a total of 288 optical fibers 11. The outer cover 110 is added to the optical fiber assembly 1, and the optical fiber cable 100 is produced. The outer diameter of the outer quilt 110 is set to 11.8 mm, and the inner diameter of the outer quilt 110 is set to 7.0 mm. The thickness of the rolled member 120 is set to 0.2 mm. The outer diameter of the optical fiber assembly 1 is approximately 6.6 mm.

In this Embodiment 2, Figure 9 is also produced using the same method as Embodiment 1. In Figure 9, position X and position Y are staggered in the longitudinal direction. Therefore, the same effect as Example 1 can be obtained.

As described above, the optical fiber assembly 1 of this embodiment (for example, Examples 1 and 2) includes a plurality of intermittently fixed core wires 10, and the plurality of intermittently fixed core wires 10 include a plurality of optical fibers 11 and are intermittently fixed in the longitudinal direction Z. A plurality of fixing portions 12 that securely fix a plurality of optical fibers 11. The optical fiber assembly 1 has an SZ twist structure. The SZ twist structure is such that a cycle including a forward twist portion 31 and a reverse twist portion 32 repeats in the longitudinal direction. , the aforementioned forward twisting part 31 is a plurality of intermittent fixed belt core wires 10 twisted together, the aforementioned counter twisting part 32 is a plurality of intermittent fixed belt core wires 10 twisted in the opposite direction to the forward twisting part 31, and is perpendicular to the long side. In the section in the direction, let the midpoint of the two optical fibers 11 located at both ends of one intermittent fixed cored wire 10 among the plurality of intermittent fixed cored wires 10 be M, and the center of gravity be G, and the midpoint M will be Let the vector starting from the center of gravity G and ending with the center of gravity G be MG, and the vector obtained by synthesizing the vector MG for all of the plurality of intermittently fixed core wires 10 be the vector sum MGtotal, the forward twisting part 31 and the reverse twisting part 32 are switched. The position X in the longitudinal direction of the inversion part B and the position Y in the longitudinal direction of the switching part are shifted due to the change in the direction of the switching vector and MGtotal. Thereby, the maximum value of the reverse twist force acting on the entire optical fiber assembly 1 can be reduced, and the occurrence of a phenomenon (twist) in which the SZ twist is released can be suppressed.

In addition, the plurality of intermittent fixed core wires 10 form a plurality of optical fiber units U, and in each of the plurality of optical fiber units U, at least two or more intermittent fixed core wires 10 among the plurality of intermittent fixed core wires 10 can also be subjected to bundle. According to this configuration, it is possible to suppress the concentration of strain on a specific optical fiber unit U, thereby suppressing an increase in the maximum transmission loss of the optical fiber assembly 1 .

Furthermore, when the size of the period in the longitudinal direction Z is denoted by P, the position X of the inversion portion B and the position Y of the switching portion may be shifted by P/128 or more in the longitudinal direction. According to this configuration, reverse twisting of the intermittently fixed core wire 10 can be suppressed.

Furthermore, the optical fiber cable 100 of this embodiment includes the above-mentioned optical fiber assembly 1 and an outer cover 110 for accommodating the optical fiber assembly 1 . According to this configuration, an increase in the maximum transmission loss of the optical fiber cable 100 can be suppressed.

Based on the above, in this embodiment, a method of manufacturing the optical fiber assembly 1 or the optical fiber cable 100 is proposed. The manufacturing method is to switch the forward twist part 31 and the reverse twist part 32 in the longitudinal direction of the reversal part B. The position X and the position Y of the switching part in the longitudinal direction of the switching vector and the direction change of MGtotal are shifted. In addition, in order to shift the position X and the position Y in the longitudinal direction, during the manufacturing process of the optical fiber assembly 1, for example, the following method can be used. The first method is a method of temporally changing the tension applied to the intermittently fixed tape core wire 10 in the process of twisting the intermittently fixed tape core wire 10 into an SZ shape. The second method is a method of temporally changing the rotation speed of the splint used when twisting the intermittently fixed core wire 10 into an SZ shape. The third method is a method of making the distance between each through hole and the center of the splint different from the plurality of through holes formed in the above-mentioned splint and through which the intermittent fixing band core wire 10 is inserted. The fourth method is a method of making each of the plurality of through holes have a different shape or size. The fifth method is a method of adjusting the length of time for which the rotation of the splint is temporarily stopped when the direction of twisting is reversed. The sixth method is a method of arranging optical fiber units with different core numbers adjacent to each other.

According to these techniques, the crepe state of each intermittently fixed core wire 10 in the cross section can be changed in the longitudinal direction. Therefore, the vector sum MGtotal can also be changed, and as a result, the position Y shown in FIGS. 8 and 9 can be controlled. Since the position X is the position of the reversal part B of the SZ twist, the position Y only needs to be shifted relative to the position X. In particular, in order to shift the position Y from the position X, the fifth method is considered to be effective. For example, the temporary stop time of the clamp when forming the inversion area can be adjusted so that the position X and the position Y are shifted by an appropriate amount. Furthermore, when two inversion areas are formed adjacent to each other in the longitudinal direction, the temporary stop times in the two inversion areas may be different from each other. Thereby, the crepe state of each intermittently fixed tape core wire 10 in the cross section can be appropriately changed in the longitudinal direction, and the position X and the position Y in the longitudinal direction can be shifted more easily.

In addition, the above-mentioned first to sixth methods are only examples, and other methods may be used as long as the optical fiber assembly 1 in which the above-mentioned relationship is established can be produced. In addition, you can also use a combination of several of the above techniques.

In addition, the technical scope of the present invention is not limited to the above-described embodiment, and various changes can be added without departing from the gist of the present invention. For example, the optical fiber assembly 1 may contain inclusions. In addition, the structures other than the optical fiber assembly 1 such as the cover material 110, the crimping material 120, the tensile member 130, the tear cord 140, etc. in the above-mentioned embodiment are only examples and can be changed appropriately. For example, the optical fiber assembly 1 of this embodiment can also be applied to a loose tube cable or the like. In addition, the above-mentioned structures other than the optical fiber assembly 1 may not be provided. That is, the optical fiber assembly 1 does not need to constitute the optical fiber cable 100 .

In addition, in the forward twisting part 31 and the reverse twisting part 32, the twisting angle (winding angle) of the inner layer unit Uin and the twisting angle (winding angle) of the outer layer unit Uout may be equal, and the period of the inner layer unit Uin (Twist pitch) and the period (twist pitch) of the outer layer unit Uout may also be equal, and the inverted portion B of the forward twist portion 31 and the reverse twist portion 32 in the inner layer unit Uin and the outer layer unit Uout is in the longitudinal direction. The positions on Z can also be equal. In addition, the structure is not limited to this. For example, the twist angle, twist pitch, or position of the inversion portion B in the inner unit Uin and the outer unit Uout may be different.

In addition, within the scope that does not deviate from the gist of the present invention, the constituent elements in the above-described embodiments can be appropriately replaced with well-known constituent elements, and the above-mentioned embodiments or modifications can also be appropriately combined.

1: Optical fiber assembly 10: Intermittent fixed core wire 11: Optical fiber 12: Fixed part 20: beam material 30: Twist pitch (period) 31: Smooth twist part 32: Counter twist part 100:Fiber optic cable 110: Outer quilt 110a:Protrusion 120: Rolled parts 130: Tension resistant body 140:Tear rope B: Reversal part G: center of gravity M: midpoint MG,MG1,MG2,MG3,MG4,MG5,MG6,MGn: vector MGtotal: vector sum O: central axis P: size U: Optical fiber unit Uin: inner unit Uout: outer unit W: Belt width direction X,Y: position Z: Long side direction +Z,-Z: direction φ: phase

FIG. 1 is a cross-sectional view showing an optical fiber assembly and an optical fiber cable according to an embodiment of the present invention. FIG. 2 is a perspective view showing the optical fiber unit according to the embodiment of the present invention. 3 is a perspective view showing intermittently fixing the core wire according to the embodiment of the present invention. FIG. 4 is a diagram explaining the SZ twist structure according to the embodiment of the present invention. 5 is a cross-sectional view showing the optical fiber unit according to the embodiment of the present invention. FIG. 6 is a diagram explaining vector MG. FIG. 7 is a diagram explaining vector sums. 8 is a diagram showing the phase of the SZ twist and the phase of the vector sum in Example 1. 9 is a diagram showing the phase of the SZ twist and the phase of the vector sum in Example 2.

1: Optical fiber assembly

10: Intermittent fixed core wire

11: Optical fiber

20: beam material

100:Fiber optic cable

110: Outer quilt

110a:Protrusion

120: Rolled parts

130: Tension resistant body

140:Tear rope

O: central axis

U: Optical fiber unit

Uin: inner unit

Uout: outer unit

Claims (5)

An optical fiber assembly is provided with a plurality of intermittently fixed core wires, and the plurality of intermittently fixed core wires include a plurality of optical fibers and a plurality of fixing portions that intermittently fix the plurality of optical fibers in a longitudinal direction, The optical fiber assembly has an SZ twisted structure, the SZ twisted structure is a structure in which a cycle including a forward twist portion and a reverse twist portion repeats in the longitudinal direction, and the forward twist portion is a twist of the plurality of intermittent fixed core wires. combined, the aforementioned counter-twisting part is the aforementioned plurality of intermittent fixed core wires twisted in the opposite direction to the aforementioned forward-twisting part, In a cross section perpendicular to the aforementioned long side direction, Let the midpoint of the two aforementioned optical fibers located at both ends of one intermittent fixed cored cord among the plurality of intermittent fixed cored cords be M, and the center of gravity be G, and the midpoint M be the starting point and the center of gravity be The vector with G as the end point is set to MG, When the vector obtained by synthesizing the vector MG for all the plurality of intermittently fixed core wires is a vector sum, The position in the longitudinal direction of the reversing portion that switches the forward twist portion and the reverse twist portion, and the position in the longitudinal direction of the switching portion that switches the direction of the vector sum are shifted. The optical fiber assembly of claim 1, wherein the aforementioned plurality of intermittent fixed core wires form a plurality of optical fiber units, In each of the plurality of optical fiber units, at least two or more of the intermittent fixed tape core wires among the plurality of intermittent fixed tape core wires are bundled. The optical fiber assembly of claim 1 or 2, wherein when the size of the period in the long side direction is set to P, The position of the reversing part and the position of the switching part are shifted by P/128 or more in the longitudinal direction. A fiber optic cable having: An optical fiber assembly such as any one of claims 1 to 3; and The outer cover piece accommodates the aforementioned optical fiber assembly. A method of manufacturing an optical fiber assembly, which is a manufacturing method of an optical fiber assembly. The optical fiber assembly is provided with a plurality of intermittently fixed core wires, and the plurality of intermittent fixed core wires include a plurality of optical fibers and a plurality of optical fibers in a longitudinal direction. A plurality of fixing portions for intermittently fixing the plurality of optical fibers; the optical fiber assembly has an SZ twist structure; the SZ twist structure is such that a cycle including a forward twist portion and a counter twist portion repeats in the longitudinal direction; The forward twisting part is the aforementioned plurality of intermittently fixed core wires twisted together, and the aforementioned reverse twisting part is the aforementioned plurality of intermittent fixed core wires twisted in the opposite direction to the aforementioned forward twisting part, In a cross section perpendicular to the aforementioned long side direction, Let the midpoint of the two aforementioned optical fibers located at both ends of one intermittent fixed cored cord among the plurality of intermittent fixed cored cords be M, and the center of gravity be G, and the midpoint M be the starting point and the center of gravity be The vector with G as the end point is set to MG, When the vector obtained by synthesizing the vector MG for all the plurality of intermittently fixed core wires is a vector sum, The position in the longitudinal direction of the reversing portion that switches the forward twist portion and the reverse twist portion, and the position in the longitudinal direction of the switching portion that switches the direction of the vector sum are shifted.

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