WO2023127420A1

WO2023127420A1 - Optical fiber assembly, optical fiber cable, and method for manufacturing optical fiber assembly

Info

Publication number: WO2023127420A1
Application number: PCT/JP2022/044824
Authority: WO
Inventors: 正敏大野; 拓哉植草; 耕司滝口; 尚人淺村; 大典佐藤; 彰鯰江; 健大里
Original assignee: 株式会社フジクラ
Priority date: 2021-12-27
Filing date: 2022-12-06
Publication date: 2023-07-06
Also published as: TWI839996B; TW202334680A

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 method for manufacturing optical fiber assembly

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

Patent Document 1 discloses a technique for preventing untwisting of SZ by unidirectionally twisting a plurality of second optical fiber ribbons onto a plurality of SZ-twisted first optical fiber ribbons. there is

Japanese Patent Application Laid-Open No. 2014-106380

As a result of intensive studies by the inventors of the present application, when a plurality of optical fiber tape core wires are SZ-twisted, the optical fiber tape core wires are twisted around their center of gravity, and the twisting direction is switched in the longitudinal direction. I understand. Furthermore, at the position where the twist direction is switched, the force that tries to cancel the twist increases, and this may cause a phenomenon (so-called untwisting) that tries to untwist the SZ strands of the optical fiber tape core wires. It turns out there is something. Untwisting leads to increased transmission loss when the optical fiber cable is bent.

The present invention has been made in consideration of such circumstances, and an object of the present invention is to provide an optical fiber assembly and an optical fiber cable capable of suppressing untwisting.

In order to solve the above-described problems, an optical fiber assembly according to one aspect of the present invention provides a plurality of intermittently fixed optical fibers including a plurality of optical fibers and a plurality of fixing portions for intermittently fixing the plurality of optical fibers in a longitudinal direction. A normal twisted portion in which the plurality of intermittently fixed tape fibers are twisted together, and a reverse twisted portion in which the plurality of intermittently fixed tape fibers are twisted in a direction opposite to the normal twisted portion. 2 located at both ends of one of the plurality of intermittently fixed tape core wires in a cross section perpendicular to the longitudinal direction, and having an SZ twist structure in which a period including Let M be the midpoint of the two optical fibers, G be the center of gravity, MG be a vector starting from the midpoint M and ending at the center of gravity G, and let MG be the vector MG for all of the plurality of intermittently fixed tape core wires. When the synthesized vector is a vector sum, the position in the longitudinal direction of the reversal portion where the forward twist portion and the reverse twist portion are switched, and the position in the longitudinal direction of the switching portion where the change in direction of the vector sum is switched. out of alignment.

In addition, a method for manufacturing an optical fiber assembly according to an aspect of the present invention includes a plurality of intermittently fixed tape core wires including a plurality of optical fibers and a plurality of fixing portions for intermittently fixing the plurality of optical fibers in a longitudinal direction. and a period including a forward twisted portion in which the plurality of intermittently fixed tape core wires are twisted together and a reverse twisted portion in which the plurality of intermittently fixed tape core wires are twisted in a direction opposite to the normal twisted portion An optical fiber assembly manufacturing method for manufacturing an optical fiber assembly having an SZ twist structure repeated in the longitudinal direction, wherein one of the plurality of intermittently fixed tape core wires is observed in a cross section perpendicular to the longitudinal direction. Let M be the midpoint of the two optical fibers located at both ends of one intermittently fixed tape core wire, let G be the center of gravity, let MG be a vector starting from the midpoint M and ending at the center of gravity G, and the vector When MG is a sum of vectors obtained by synthesizing all of the plurality of intermittently fixed tape core wires, the position in the longitudinal direction of the reversal portion where the forward twist portion and the reverse twist portion are switched, and the direction of the vector sum. The position in the longitudinal direction of the switching portion where the change is switched is shifted.

According to the above aspect of the present invention, it is possible to provide an optical fiber assembly and an optical fiber cable capable of suppressing untwisting.

1 is a cross-sectional view showing an optical fiber assembly and an optical fiber cable according to an embodiment of the invention; FIG. 1 is a perspective view showing an optical fiber unit according to an embodiment of the invention; FIG. 1 is a perspective view showing an intermittently fixed tape core wire according to an embodiment of the present invention; FIG. It is a figure explaining SZ twist structure concerning the embodiment of the present invention. 1 is a cross-sectional view showing an optical fiber unit according to an embodiment of the invention; FIG. It is a figure explaining vector MG. It is a figure explaining a vector sum. 4 is a diagram showing the phase of SZ twist and the phase of vector sum according to Example 1. FIG. FIG. 10 is a diagram showing the phase of SZ twist and the phase of vector sum according to Example 2;

An optical fiber assembly 1 and an optical fiber cable 100 according to embodiments of the present invention will be described below with reference to the drawings.
As shown in FIG. 1, the optical fiber cable 100 according to this embodiment includes an optical fiber aggregate 1 including a plurality of optical fiber units U. As shown in FIG. As shown in FIG. 2, each optical fiber unit U has a plurality of intermittently fixed fiber ribbons 10 . In other words, the plurality of intermittently fixed fiber ribbons 10 constitute the plurality of optical fiber units U. As shown in FIG. Also, each intermittent fixing tape core wire 10 includes a plurality of optical fibers 11 . In other words, the plurality of optical fibers 11 constitute the plurality of intermittently fixed tape 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 be 200 μm, or may be another value.

(direction definition)
Here, in this embodiment, the longitudinal direction of the optical fiber assembly 1 (optical fiber cable 100) is simply referred to as the longitudinal direction Z. As shown in FIG. The longitudinal direction Z is also a direction parallel to the central axis O of the optical fiber assembly 1 (optical fiber cable 100). One orientation along the longitudinal direction Z is referred to as the +Z orientation or forward. The orientation opposite to the +Z orientation is referred to as the -Z orientation or back. A section perpendicular to the longitudinal direction Z is called a transverse section. Viewing a cross section from the longitudinal direction Z is called a cross section view. A direction perpendicular to the central axis O of the optical fiber assembly 1 (optical fiber cable 100) is referred to as a radial direction. Along the radial direction, the direction approaching the central axis O is referred to as the radial inner side, and the direction away from the central axis O is referred to as the radial outer side. The direction of rotation around the central axis O when viewed from the longitudinal direction Z is called the circumferential direction.

As shown in FIG. 1, the optical fiber cable 100 according to this embodiment is a so-called slotless optical cable. That is, the optical fiber cable 100 according to this embodiment does not have a slot rod in which a groove (slot groove) for accommodating the optical fiber 11 (the intermittent fixing tape core wire 10) is formed. However, the optical fiber cable 100 may be a slot type optical cable having a slot rod. In this case, the optical fiber assembly 1 according to this embodiment may be accommodated in the slot groove of the optical fiber cable 100 .

As shown in FIG. 1, the optical fiber cable 100 according to the present embodiment includes the optical fiber assembly 1 described above, a pressure wrap 120 covering the optical fiber assembly 1, and the optical fiber assembly 1 via the pressure wrap 120. and a jacket 110 that covers and houses the . In other words, the optical fiber assembly 1 can be regarded as a portion of the optical fiber cable 100 excluding the jacket 110, the pressure wrap 120, and the like. Also, the optical fiber assembly 1 and the pressure winding 120 may be collectively referred to as a core.

The pressure wrap 120 is a tape-shaped member that bundles the plurality of optical fiber units U. As shown in FIG. The type of the pressing wrap 120 is not particularly limited as long as the optical fiber units U can be bundled. The press wrap 120 may have water absorbency. The pressure winding 120 may be wound vertically or horizontally with respect to the optical fiber assembly 1, for example.
For example, when the pressure wrap 120 is a tape extending in the longitudinal direction Z, the pressure wrap 120 may be formed in a cylindrical shape that wraps the optical fiber unit U. In this case, both ends in the circumferential direction of the pressure winding 120 may overlap each other to form a wrap portion. Also, the pressing wrap 120 may be a tube forming body that wraps the optical fiber unit U instead of the tape. By wrapping the optical fiber unit U with the pressing wrap 120 in the longitudinal direction Z, the optical fiber 11 can be protected.
Note that there may be a portion in the longitudinal direction Z where the optical fiber 11 is not wrapped by the pressure wrap 120 , and the optical fiber cable 100 may not have the pressure wrap 120 .

Polyolefins such as polyethylene (PE), polypropylene (PP), ethylene ethyl acrylate copolymer (EEA), ethylene vinyl acetate copolymer (EVA), ethylene propylene copolymer (EP), etc. PO) resin, polyvinyl chloride (PVC), and the like can be used. Moreover, the jacket 110 may be formed using a mixture (alloy, mixture) of the above resins. Moreover, various additives may be added to the jacket 110 depending on the purpose. Examples of additives include flame retardants, colorants, antidegradants, inorganic fillers, and the like. Also, the jacket 110 may have a two-layer structure or other multi-layer structure. For example, a protective layer covering the outer cover 110 is provided outside the outer cover 110 (first outer cover) in the illustrated example, and a second outer cover covering the protective layer is provided outside the protective layer. may The protective layer may be made of, for example, metal or fiber reinforced plastic (FRP). Alternatively, jacket 110 may have no protective layer and may simply be formed by multiple layers of jacket.

The external shape of the jacket 110 according to the present embodiment is substantially circular in cross-sectional view, except for projections 110a, which will be described later. However, the shape of the jacket 110 can be changed as appropriate. As shown in FIG. 1, a plurality of (four in the illustrated example) tensile strength members 130 and a pair of ripcords 140 are arranged on the jacket 110 according to the present embodiment.

The tensile strength member 130 is a member having a higher spring constant or tensile strength in the longitudinal direction Z than the jacket 110 . As the material of the tensile strength member 130, for example, a metal wire (steel wire or the like), a material in which metal wires are bundled, a glass fiber, a material in which glass fibers are bundled, or the like can be used. Alternatively, fiber reinforced plastic (FRP) or the like may be used as the tensile member 130 . The tensile member 130 has a role of receiving the tension and protecting the optical fibers 11 when the tension along the longitudinal direction Z is applied to the optical fiber assembly 1 (optical fiber cable 100).
A plurality of strength members 130 are disposed on the jacket 110 . A plurality of tensile members 130 according to this embodiment are arranged so as to sandwich the optical fiber assembly 1 in the radial direction. However, the plurality of tensile members 130 may be isotropically arranged on the jacket 110 so as to surround the optical fiber assembly 1 (core). Note that the tensile strength member 130 may not be embedded in the jacket. For example, strength member 130 may be included in the center or core of optical fiber assembly 1 . Alternatively, depending on the application of the optical fiber cable 100, the optical fiber cable 100 may not have the strength member 130. FIG.

A ripcord 140 is a member used to tear the jacket 110 . As a material of the rip cord 140, for example, synthetic fiber (polyester or the like) thread, polypropylene (PP) or nylon cylindrical rod, or the like can be used.
A ripcord 140 is disposed on the jacket 110 . Note that, in a cross-sectional view, the ripcord 140 may be arranged so that the entire circumference is embedded in the outer cover 110, or may be partially exposed from the outer peripheral surface or the inner peripheral surface of the outer cover 110. may be placed. A pair of ripcords 140 according to this embodiment are arranged so as to sandwich the optical fiber assembly 1 in the radial direction. In addition, the position of each tensile strength member 130 and the position of each ripcord 140 are shifted from each other in the circumferential direction. Note that the number of ripcords 140 may be one, or three or more. Also, the ripcord 140 may not be embedded in the jacket 110 . For example, the ripcord 140 may be tandemly attached to the optical fiber assembly 1 . Alternatively, fiber optic cable 100 may not have ripcord 140 .

A pair of protrusions 110a projecting radially outward from the outer peripheral surface of the outer cover 110 are provided on the outer cover 110 according to the present embodiment. The position of the projection 110a in the circumferential direction and the position of the ripcord 140 correspond to each other. The protrusion 110 a serves as a mark that makes it easier for the user to recognize the position of the ripcord 140 from the outside of the optical fiber cable 100 . Note that the outer cover 110 may not have the projections 110a. In this case, the protrusions 110a may be replaced by linear coloring on the jacket 110. FIG. However, the outer cover 110 does not have to have the projections 110a, and the outer cover 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, an optical fiber assembly 1 including a plurality of optical fiber units U according to this embodiment has a two-layer structure. That is, the multiple optical fiber units U include multiple (nine in the illustrated example) outer layer units Uout and multiple (three in the illustrated example) inner layer units Uin. Each outer layer unit Uout is located on the outer circumference of the optical fiber assembly 1 . The plurality of inner layer units Uin are surrounded from the radially outer side by the plurality of outer layer units Uout. That is, the plurality of inner layer units Uin are positioned 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 as appropriate. Also, the optical fiber assembly 1 does not have to have a two-layer structure.

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

The bundle material 20 is a member capable of bundling a plurality of intermittently fixed tape core wires 10 . As the bundle material 20, for example, a thread-like, string-like, tape-like member, or the like can be used. The intermittently fixed fiber ribbon 10 according to the present embodiment is bundled by winding a bundle material 20 thereon. However, the configuration in which the bundle material 20 bundles the intermittently fixed tape core wires 10 is not limited to the illustrated example. For example, the bundle material 20 may be spirally wound around the intermittent fixing ribbon 10 . Alternatively, the optical fiber unit U may not have the bundle material 20 . In this case, for example, the intermittently fixed tape core wires 10 may be bundled by twisting a plurality of the intermittently fixed tape core wires 10 in the optical fiber unit U.

The optical fiber assembly 1 may not have the optical fiber unit U. In other words, the plurality of intermittently fixed ribbon 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 pressure wrap 120 and the jacket 110 directly cover the intermittently fixed tape cable core 10 .
Further, in the example shown in FIG. 1, the inner layer unit Uin is formed in a fan shape, and the outer layer unit Uout is formed in a square shape. The cross-sectional shape of the optical fiber unit U is not limited to the illustrated example, and may be circular, elliptical, or polygonal. Further, even when the optical fiber 11 is bundled with the bundle material 20 , the bundle material 20 is deformed, and the optical fiber 11 appropriately moves to an empty space inside the jacket 110 . Therefore, for example, as shown in FIG. 5, the cross-sectional shape of the optical fiber unit U may be deformed.

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

Each fixing portion 12 fixes two optical fibers 11 adjacent in the tape width direction W to each other. A gap may be provided between two adjacent optical fibers 11 . In this case, a plurality of fixing portions 12 are intermittently arranged in the longitudinal direction Z in the gap. 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 set, and a plurality of optical fiber sets may be intermittently fixed by a plurality of fixing portions 12 .
As shown in FIG. 3, the plurality of fixing portions 12 are two-dimensionally intermittently arranged in the longitudinal direction Z and the tape width direction W. As shown in FIG. Note that the arrangement of the fixing portion 12 is not limited to the example in FIG. 3, and can be changed as appropriate. Also, the arrangement pattern of the fixed portions 12 may not be a constant pattern in the longitudinal direction Z or the tape width direction W. The arrangement pattern of the fixing portions 12 does not have to be a constant pattern between different intermittently fixed tape core wires 10 . As the material of the fixed part 12, for example, a UV curable resin may be adopted. However, the material of the fixing portion 12 is not particularly limited as long as the adjacent optical fibers can be fixed, and can be changed as appropriate.

As shown in FIG. 4, in the optical fiber assembly 1, the plurality of optical fiber units U and the plurality of intermittently fixed tape core wires 10 included therein are twisted in an SZ shape. More specifically, the optical fiber assembly 1 has an SZ-twisted structure in which a period 30 including forward-twisted portions 31 and reverse-twisted portions 32 is repeated in the longitudinal direction Z. FIG. Period 30 is also referred to as twist pitch. The longitudinal dimension of period 30 is denoted herein as P. As shown in FIG. In each of the forward-twisted portion 31 and the reverse-twisted portion 32, a plurality of optical fiber units U and a plurality of intermittently fixed fiber ribbons 10 included therein are twisted together.

More specifically, each optical fiber unit U (intermittently fixed tape core wire 10 ) is wound around the central axis O of the optical fiber assembly 1 in each of the forward twisted portion 31 and the reverse twisted portion 32 . As shown in FIG. 4, the direction in which the optical fiber assembly 1 is twisted in the forward twisting portion 31 and the direction in which the optical fiber assembly 1 is twisted in the reverse twisting portion 32 are opposite to each other. In the normal twisted portion 31 and the reverse twisted portion 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 or different.
In this specification, the position in the longitudinal direction where the forward twisted portion 31 and the reverse twisted portion 32 of the SZ twist structure are switched is referred to as a "reversal portion B". Two reversals B appear per period 30 (dimension P in the longitudinal direction) in the SZ twist structure.

As shown in FIG. 5, in the optical fiber assembly 1 according to the present embodiment, the plurality of intermittently fixed tape core wires 10 are stacked in a collapsed state when viewed in cross section. In FIG. 5, the optical fibers 11 belonging to the same intermittent fixing ribbon 10 are connected by solid lines. In addition, the “collapsed state” means a state in which at least one intermittent fixing tape core wire 10 included in the optical fiber assembly 1 is curved.

In this specification, a vector MG defined as follows is introduced in order to evaluate the state of collapse of the intermittent fixation ribbon core 10 . Here, FIG. 6 is a cross-sectional view of the optical fiber assembly 1 (optical fiber unit U) shown in FIG. 5 plotted on the xy plane. In FIG. 6, each of the six intermittently fixed tape core wires 10 included in the optical fiber unit U is called a first tape to a sixth tape.

The vector MG is a vector quantity defined for each intermittently fixed tape core wire 10 at each position in the longitudinal direction Z of the optical fiber assembly 1 . Let M be the middle point of the two optical fibers 11 positioned at both ends of the optical fibers 11 forming the intermittent fixing tape core wire 10 in the cross section, and let G be the center of gravity of the intermittent fixing tape core wire 10 . As shown in FIG. 6, the vector MG is a vector starting at the midpoint M and ending at the center of gravity G. As shown in FIG. In FIG. 6, the vector MG defined for the first tape is called vector MG1, and the vector MG defined for the second tape is called vector MG2. The same applies to the third to sixth tapes. It is extremely rare for the midpoint M and the center of gravity G to coincide with each other when the intermittent fixing tape cord 10 is collapsed (curved).

Here, in this specification, the vector sum MGtotal is defined as follows. The vector sum MGtotal is obtained by synthesizing the vectors MG for all the intermittently fixed tape fibers 10 included in the optical fiber assembly 1 . In FIG. 7, the vector of each intermittently fixed fiber ribbon 10 is represented as MGn. A vector sum MGtotal is obtained by synthesizing these vectors MGn. Furthermore, 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.

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

(Example 1)
An optical fiber assembly 1 having three inner layer units Uin and nine outer layer units Uout was prepared. Each of the inner layer unit Uin and the outer layer unit Uout is obtained by binding six intermittently fixed tape core wires 10 with a bundle material. Each intermittent fixing tape 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 was set to 250 μm. An optical fiber cable 100 was produced by wrapping this optical fiber assembly 1 with a pressure wrap 120 and covering it with a jacket 110 . The outer diameter of the jacket 110 was 18.2 mm, and the inner diameter of the jacket 110 was 11.5 mm. The thickness of the pressure winding 120 was set to 0.2 mm. The outer diameter of the optical fiber assembly 1 was approximately 11.1 mm.

The above optical fiber cable 100 was cut at equal intervals in the longitudinal direction to obtain a total of nine cross sections. More specifically, the optical fiber cable 100 was cut every P/8. After cutting in this way, the optical fiber assembly 1 was hardened with an epoxy resin, the hardened optical fiber assembly 1 was polished so that the cross section became clear, and an image of the cross section was taken with a microscope. The position of each optical fiber 11 was plotted on the xy plane on the image obtained by the microscope. The optical fiber assembly 1 may be fixed with epoxy resin, and then the optical fiber cable 100 may be cut at each position in the longitudinal direction. In this case, the sheath 110 may be filled with the epoxy resin, for example, by injecting the epoxy resin from one end in the longitudinal direction of the optical fiber cable 100 and sucking the epoxy resin from the other end.

For each cross-section obtained by cutting, the SZ twist phase and the above-mentioned vector sum phase φ were obtained and plotted as shown in FIG. The SZ twist phase may be the angle at which each optical fiber unit U (intermittently fixed tape cable core 10 ) is wound around the central axis O of the optical fiber assembly 1 . The horizontal axis of FIG. 8 represents the position in the longitudinal direction. For example, between "0.1" and "0.2" on the horizontal axis, there is a distance of 0.1P in the longitudinal direction. Further, based on the plot of the phase of the SZ twist, a sine curve as an approximation curve is indicated by a solid line, and X is the position in the longitudinal direction where the sine curve is minimum. Similarly, based on the plot of the phase φ of the vector sum, the sine curve as an approximate curve is indicated by a dashed line, and Y is the position in the longitudinal direction where the sine curve is minimum. An optimum approximation curve (sine curve) can be obtained using, for example, the method of least squares. A specific numerical value of the phase φ of the vector sum may be obtained from the recurrence formula of the approximate curve.

As shown in FIG. 8, the reason why the phase φ of the vector sum transitions in the longitudinal direction so as to draw a substantially sine curve is that the cross-sectional shape collapse of the intermittently fixed fiber ribbon 10 follows the SZ twist. A more detailed description will be given below.

When the intermittently fixed tape core wires 10 are SZ-twisted, each intermittently fixed tape core wire 10 changes its position in the circumferential direction so as to swing around the central axis O. At the same time, each of the intermittently fixed ribbon cords 10 is often twisted around its own center of gravity when viewed macroscopically. Conceptually, the former is similar to "revolution" and the latter is similar to "rotation", so they are called "revolution" and "rotation" in this specification.

As for "rotation", each intermittently fixed tape core wire 10 is not continuously twisted in one direction, but the twisting direction is switched at predetermined intervals in the longitudinal direction. The position in the longitudinal direction where the twisting direction of the intermittently fixed ribbon core 10 is switched in this manner can be regarded as the position Y shown in FIG. On the other hand, the position X in the longitudinal direction is the position of the inverted portion B itself. That is, the normal twisted portion 31 and the reverse twisted portion 32 are switched with the position X as a boundary, and the twisting direction of each intermittently fixed ribbon core 10 is switched with the position Y as a boundary.

When the intermittently fixed tape cord 10 is SZ-twisted, the untwisting force at the reversal portion B increases. Similarly, when the intermittent fixing tape core wire 10 is twisted, the force to cancel the twist increases at the portion (switching portion) where the twisting direction is switched. The latter "force to untwist" also acts as a force to undo the SZ twist. Here, in this embodiment, the position X and the position Y are shifted in the longitudinal direction. In other words, the point (position X) where the untwisting force caused by "revolution" is maximized and the point (position Y) where the untwisted force caused by "rotation" is maximized are shifted in the longitudinal direction. As a result, it is possible to prevent the two forces from becoming maximum at one point, and to reduce the maximum value of the untwisting force acting on the optical fiber assembly 1 as a whole. Therefore, it is possible to suppress the occurrence of a phenomenon in which the SZ twist is canceled (untwist).

Table 1 shows the result of considering how much the position X and the position Y should deviate.

The "judgment" shown in Table 1 indicates the magnitude of the risk of untwisting of the SZ twist. If the determination is "C", it means that untwisting is likely to occur. If the determination is "B", it means that untwisting is less likely to occur. If the determination is "A", it means that the risk of untwisting is remarkably small. As shown in Table 1, by setting the distance in the longitudinal direction between the position X and the position Y to P/128 or more, an effect of suppressing untwisting can be expected. Furthermore, by setting the distance in the longitudinal direction between the position X and the position Y to P/64 or more, the effect of suppressing untwisting 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 divided into an inner layer and an outer layer. In Example 2, the intermittently fixed tape cord 10 was SZ-twisted without being bundled with the bundle material 20 and without being divided into an inner layer and an outer layer. The number of the intermittently fixed tape core wires 10 included in the optical fiber assembly 1 was 24, and the number of the optical fibers 11 included in each intermittently fixed tape core wire 10 was 12 pieces. In other words, the optical fiber assembly 1 of Example 2 has a total of 288 optical fibers 11 . A jacket 110 was applied to this optical fiber assembly 1 to prepare an optical fiber cable 100 . The outer diameter of the jacket 110 was 11.8 mm, and the inner diameter of the jacket 110 was 7.0 mm. The thickness of the pressure winding 120 was set to 0.2 mm. The outer diameter of the optical fiber assembly 1 was approximately 6.6 mm.

Also in this second embodiment, FIG. 9 was created by the same method as in the first embodiment. Also in FIG. 9, the position X and the position Y are shifted in the longitudinal direction. Therefore, an effect similar to that of the first embodiment can be obtained.

As described above, the optical fiber assembly 1 according to the present embodiment (for example, Examples 1 and 2) includes a plurality of optical fibers 11 and a plurality of fixing members for intermittently fixing the plurality of optical fibers 11 in the longitudinal direction Z. A plurality of intermittently fixed fiber ribbons 10 including portions 12 are provided, and a forward twisted portion 31 in which the plurality of intermittently fixed fiber ribbons 10 are twisted together, and the plurality of intermittently fixed fiber ribbons 10 are oriented in a direction opposite to that of the forward twisted portion 31. and an SZ-twisted structure in which the cycle is repeated in the longitudinal direction, and one of the plurality of intermittently fixed tape core wires 10 is intermittently fixed in a cross section perpendicular to the longitudinal direction. Let M be the midpoint of the two optical fibers 11 positioned at both ends of the optical fiber 10, G be the center of gravity, and MG be a vector starting from the midpoint M and ending at the center of gravity G, and the vector MG is intermittent. Assuming that the vector sum MGtotal is the vector synthesized for all of the fixed ribbon cores 10, the position X in the longitudinal direction of the reversing portion B where the forward twisting portion 31 and the reverse twisting portion 32 are switched, and the change in the direction of the vector sum MGtotal are switched. The position Y in the longitudinal direction of the switching portion is displaced. This makes it possible to reduce the maximum value of the untwisting force acting on the optical fiber assembly 1 as a whole, and suppress the occurrence of a phenomenon in which the SZ twist is canceled (untwisting).

Further, the plurality of intermittently fixed tape 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 of the plurality of intermittently fixed tape core wires 10 are intermittently The fixing tape cable core 10 may be bundled. According to this configuration, concentration of strain on a specific optical fiber unit U can be suppressed, and an increase in the maximum transmission loss of the optical fiber assembly 1 can be suppressed.

Further, when the period dimension in the longitudinal direction Z is P, the position X of the reversing 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, untwisting of the intermittently fixed ribbon cable 10 can be suppressed.

Further, the optical fiber cable 100 according to this embodiment includes the above-described optical fiber assembly 1 and a jacket 110 that accommodates the optical fiber assembly 1 . According to this configuration, it is possible to suppress an increase in the maximum transmission loss of the optical fiber cable 100 .

Based on the above, in the present embodiment, the position X in the longitudinal direction of the reversing portion B at which the normal twist portion 31 and the reverse twist portion 32 are switched, the position Y in the longitudinal direction of the switching portion at which the change in the direction of the vector sum MGtotal is switched, A method for manufacturing an optical fiber assembly 1 or an optical fiber cable 100 is proposed.
In order to shift the position X and the position Y in the longitudinal direction, for example, the following technique is used in the manufacturing process of the optical fiber assembly 1 . The first method is to change the tension applied to the intermittently fixed tape core wires 10 with time in the process of twisting the intermittently fixed tape core wires 10 in an SZ shape. A second technique is to change the rotational speed of battens used when intermittently fixing ribbon cords 10 are twisted in an SZ shape with time. A third method is a method of varying the distance between each through-hole and the center of the batten plate for a plurality of through-holes formed in the batten plate and through which the intermittent fixing tape core wires 10 are inserted. . A fourth technique is to vary the shape and size of each of the plurality of through holes. A fifth technique is to adjust the length of the pause time (the rotation of the battens) when reversing the twisting direction. A sixth method is a method of arranging optical fiber units having different numbers of cores adjacent to each other.

According to these methods, it is possible to change the collapsed state of each intermittently fixed ribbon cable 10 in the cross section in the longitudinal direction. Therefore, the vector sum MGtotal can also be changed, and eventually the position Y shown in FIGS. 8 and 9 can be controlled. Since the position X is exactly the position of the reversal portion B of the SZ twist, the position Y should be shifted with respect to this position X. In particular, the fifth technique is considered effective for shifting the position Y from the position X. For example, it is possible to adjust the temporary stop time of the battens when forming the reversal area so that the position X and the position Y have an appropriate amount of deviation. Also, when forming two reversed regions adjacent in the longitudinal direction, the pause times in the two reversed regions may be different from each other. As a result, it is possible to suitably change the collapsed state of each intermittent fixing ribbon 10 in the cross section in the longitudinal direction, and to more easily shift the position X and the position Y in the longitudinal direction.

The above-described first to sixth methods are examples, and other methods may be used as long as the optical fiber assembly 1 that satisfies the above relationship can be manufactured. Also, some of the methods described above may be used in combination.

The technical scope of the present invention is not limited to the above embodiments, and various modifications can be made without departing from the scope of the present invention.
For example, the optical fiber assembly 1 may contain inclusions.
Also, the structures other than the optical fiber assembly 1, such as the jacket 110, the pressure wrap 120, the tension member 130, the ripcord 140, etc., in the above embodiment are all examples, and can be changed as appropriate. For example, the optical fiber assembly 1 according to this embodiment may be applied to a loose tube cable or the like. Moreover, the above configuration other than the optical fiber assembly 1 may be omitted. In other words, the optical fiber assembly 1 does not have to constitute the optical fiber cable 100 .

Further, in the forward twisted portion 31 and the reverse twisted portion 32, the twist angle (winding angle) of the inner layer unit Uin and the twist angle (winding angle) of the outer layer unit Uout are equal, and the cycle (twist pitch) of the inner layer unit Uin and the outer layer unit Uin are equal. The cycles (twisting pitches) of the units Uout may be the same, and the positions in the longitudinal direction Z of the reversal portions B of the forward twisted portion 31 and the reverse twisted portion 32 of the inner layer unit Uin and the outer layer unit Uout may be the same. Further, the configuration is not limited to this, and for example, the twist angle, the twist pitch, or the position of the reversal portion B may be different between the inner layer unit Uin and the outer layer unit Uout.

In addition, it is possible to appropriately replace the components in the above-described embodiments with well-known components within the scope of the present invention, and the above-described embodiments and modifications may be combined as appropriate.

1 Optical fiber assembly 10 Intermittent fixing tape core wire 11 Optical fiber 12 Fixing part 31 Normal twist part 32 Reverse twist part B... Inverted part G... Center of gravity M... Middle point MG... Vector MGtotal... Vector sum U... fiber optic unit

Claims

A plurality of intermittently fixed ribbon core wires including a plurality of optical fibers and a plurality of fixing portions for intermittently fixing the plurality of optical fibers in the longitudinal direction,
A period including a forward twisted portion in which the plurality of intermittently fixed tape core wires are twisted together and a reverse twisted portion in which the plurality of intermittently fixed tape core wires are twisted in a direction opposite to the normal twisted portion is defined in the longitudinal direction. has an SZ twist structure repeated in
In a cross section perpendicular to the longitudinal direction,
In one intermittently fixed tape core wire among the plurality of intermittently fixed tape core wires, the midpoint of the two optical fibers located at both ends is M, the center of gravity is G, and the center of gravity is set with the midpoint M as the starting point. Let MG be a vector with G as the end point,
When the sum of vectors obtained by synthesizing the vector MG with respect to all of the plurality of intermittently fixed tape fibers,
An optical fiber assembly, wherein a position in the longitudinal direction of a reversal portion at which the forward twist portion and the reverse twist portion are switched is shifted from a position in the longitudinal direction of a switching portion at which the change in direction of the vector sum is switched.
The plurality of intermittently fixed tape core wires form a plurality of optical fiber units,
2. The optical fiber assembly according to claim 1, wherein at least two of said plurality of intermittently fixed tape core wires are bundled in each of said plurality of optical fiber units.
When the dimension of the period in the longitudinal direction is P,
3. The optical fiber assembly according to claim 1, wherein a position of said reversing portion and a position of said switching portion are deviated from each other by P/128 or more in said longitudinal direction.
an optical fiber assembly according to any one of claims 1 to 3;
and a jacket that houses the assembly of optical fibers.
A plurality of intermittently fixed tape core wires including a plurality of optical fibers and a plurality of fixing portions for intermittently fixing the plurality of optical fibers in a longitudinal direction, wherein the intermittently fixed tape core wires are twisted together in a normal twisted portion. and a counter-twisted portion in which the plurality of intermittently fixed tape core wires are twisted in a direction opposite to the forward-twisted portion. A method for manufacturing an optical fiber assembly,
In a cross section perpendicular to the longitudinal direction,
In one intermittently fixed tape core wire among the plurality of intermittently fixed tape core wires, the midpoint of the two optical fibers located at both ends is M, the center of gravity is G, and the center of gravity is set with the midpoint M as the starting point. Let MG be a vector with G as the end point,
When the sum of vectors obtained by synthesizing the vector MG with respect to all of the plurality of intermittently fixed tape fibers,
A method for manufacturing an optical fiber assembly, wherein a position in the longitudinal direction of a reversing portion where the forward twisting portion and the reverse twisting portion are switched is shifted from a position in the longitudinal direction of the switching portion where the change in direction of the vector sum is switched. .