WO2023127418A1 - Optical fiber assembly, optical fiber cable, and method for manufacturing optical fiber assembly - Google Patents

Abstract

This optical fiber assembly is provided with a plurality of intermittently-fixed optical fiber ribbons and has an SZ twisting structure in which a cycle including a forward-twisted part and a reverse-twisted part is repeated in a longitudinal direction. In a cross section perpendicular to the longitudinal direction, when, in one intermittently-fixed optical fiber ribbon from among the plurality of intermittently-fixed optical fiber ribbons, the midpoint of two of the optical fibers positioned at both ends is denoted by M, the center of gravity is denoted by G, a vector having the midpoint M as a starting point and the center of gravity G as an end point is denoted by MG, a vector obtained by synthesizing the vector MG with respect to all of the plurality of intermittently-fixed optical fiber ribbons is denoted by GU, and the magnitude of the vector GU is denoted as a scalar quantity L, the average value of the scalar quantity L in all inverted regions is greater than the average value of the scalar quantity L in all rotated regions.

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. 2021-212144 filed in Japan on December 27, 2021, the content of which is incorporated herein.

Patent Document 1 discloses an optical fiber cable having a plurality of optical fiber units collectively covered with a jacket. Each optical fiber unit includes a plurality of intermittently fixed ribbon ribbons.

Japanese Patent Application Laid-Open No. 2014-16530

By the way, in the optical fiber cable shown in Patent Document 1, for example, when bending occurs or when the jacket shrinks in a low-temperature environment, strain may concentrate on a specific intermittently fixed tape core wire. Such strain concentrations have sometimes resulted in an increase in the maximum transmission loss of the fiber optic cable (optical fiber assembly).

The present invention has been made in consideration of such circumstances, and aims to provide an optical fiber assembly, an optical fiber cable, and an optical fiber assembly manufacturing method that can suppress an increase in maximum transmission loss.

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. It has an SZ twist structure in which the period including is repeated in the longitudinal direction, the dimension of one period in the longitudinal direction is P, the dimension in the longitudinal direction is P / 4, and the center in the longitudinal direction is the A region located at the boundary between the normal twisted portion and the reverse twisted portion is referred to as a reversed region, and a region located between the reversed regions in the longitudinal direction is referred to as a rotated region. In one intermittently fixed tape core wire among a 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 G with the midpoint M as the starting point. is the end point, MG is a vector obtained by synthesizing the vector MG with respect to all of the plurality of intermittently fixed fiber ribbons, and GU is a vector obtained by synthesizing the vector MG with respect to all the intermittently fixed fiber ribbons. is larger than the average value of the scalar quantity L in all the rotation regions.

Further, in the method for manufacturing an optical fiber assembly according to an aspect of the present invention, the vector GU in the reversal region is the same as the vector GU in one of the two rotational regions adjacent to the reversal region in the longitudinal direction. , and the vector GU in the other of the two rotation regions adjacent to the inversion region.

According to the above aspect of the present invention, it is possible to provide an optical fiber assembly, an optical fiber cable, and a method for manufacturing an optical fiber assembly capable of suppressing an increase in maximum transmission loss.

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. FIG. 4 is a diagram showing transitions of scalar amounts L, Lin, and Lout for the optical fiber assembly according to Example 1 of the present invention; FIG. 4 is a diagram showing vectors GU, GUin, and GUout in a certain rotation region for the optical fiber assembly according to Example 1 of the present invention; FIG. 8B is a diagram showing vectors GU, GUin, and GUout in the inversion region adjacent to the rotation region shown in FIG. 8A for the optical fiber assembly according to Example 1 of the present invention; FIG. 8C is a diagram showing vectors GU, GUin, and GUout in the rotation area adjacent to the inversion area shown in FIG. 8B for the optical fiber assembly according to Example 1 of the present invention; FIG. 8B is a diagram showing vectors GU, GUin, and GUout in the inversion region adjacent to the rotation region shown in FIG. 8C for the optical fiber assembly according to Example 1 of the present invention; FIG. 5 is a diagram showing transitions of scalar amounts L, Lin, and Lout for an optical fiber assembly according to Example 2 of the present invention;

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. In other words, the optical fiber assembly 1 may have a structure in which the pressure wrap 120 or the jacket 110 directly covers the intermittent fixing tape core wire 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 30 . 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.

Here, in this specification, for the purpose of facilitating the following description, the reversal region 41 and the rotation region 42 are defined for the optical fiber assembly 1 as shown in FIG. The reversal region 41 is a region that extends in the longitudinal direction Z around the boundary B between the forward twisted portion 31 and the reverse twisted portion 32 . In other words, the reversal region 41 is a region in which the direction in which the intermittently fixed fiber ribbons 10 are twisted is reversed. The dimension of the reversed region 41 in the longitudinal direction Z is P/4, where P is the dimension of the period (twist pitch) 30 . A rotation area 42 is an area other than the inversion area 41 . In other words, the rotation area 42 is an area located between the inversion areas 41 . The rotation area 42 is an area in which the intermittently fixed ribbon core 10 is twisted (wound) in one direction. In the optical fiber assembly 1, the reversal regions 41 and the rotation regions 42 are alternately repeated in the longitudinal direction Z. As shown in FIG.

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. Also, the shape of the laminated intermittent fixing ribbons 10 differs between the cross section in the reversal region 41 and the cross section in the rotation region 42 . In other words, the collapsed state of the intermittently fixed ribbon core 10 differs between the reversal region 41 and the rotation region 42 . In other words, the cross-sectional shape of the optical fiber assembly 1 differs between the reversed region 41 and the rotated region 42 .

In this specification, vectors MG, GU, GUin, and GUout and scalar quantities L, Lin, and Lout defined as follows are 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).

Vectors GU, GUin, and GUout are vector quantities defined for each position in the longitudinal direction Z of the optical fiber assembly 1 . The vector GU is a vector obtained by synthesizing the vector MG for all the intermittently fixed tape core wires 10 included in the optical fiber assembly 1 . The vector GUin is a vector obtained by synthesizing the vector MG for all the intermittently fixed fiber ribbons 10 included in all the inner layer units Uin. Vector GUout is a vector obtained by synthesizing all intermittently fixed fiber ribbons 10 included in all outer layer units Uout.

Here, the feature that "the state of collapse of the intermittently fixed ribbon core 10 differs between the reversal region 41 and the rotation region 42" described above can be rephrased as follows using the vector GU. That is, the vector GU in the reverse region 41 is the vector GU in one of the two rotational regions 42 adjacent to the reverse region 41 in the longitudinal direction Z, and the vector GU in one of the two rotational regions 42 adjacent to the reverse region 41 in the longitudinal direction Z vector GU on the other.

The scalar quantities L, Lin, and Lout are scalar quantities defined for each position in the longitudinal direction Z of the optical fiber assembly 1 . The scalar quantity L is the magnitude of vector GU. The scalar quantity Lin is the magnitude of the vector GUin. The scalar quantity Lout is the magnitude of the vector GUout. As can be seen from the above definition, the scalar quantity L is a quantity that characterizes the collapsed state of the intermittently fixed fiber ribbon 10 . More specifically, the greater the scalar amount L, the more the intermittently fixed fiber ribbon 10 is considered to have collapsed. This is because the larger the curvature of the intermittently fixed optical fiber ribbon 10 (the more the intermittently fixed optical fiber ribbon 10 is collapsed), the larger the magnitude of the vector MG, and the scalar amount of the vector GU, which is a vector obtained by combining the vectors MG ( This is because it is thought that the size) L will also increase.

The above embodiments will be described below using specific examples. In addition, the present invention is not limited to the following examples.

(Example 1)
As the optical fiber assembly 1 and the optical fiber cable 100 according to Example 1, an 864-core optical fiber assembly and an optical fiber cable according to the above embodiment were produced. The optical fiber assembly 1 according to Example 1 had 12 optical fiber units U. As shown in FIG. Each optical fiber unit U had six intermittently fixed tape core wires 10 bundled with a bundle material 20 . Each intermittent fixing tape core wire 10 contained 12 optical fibers 11 . Also, at each position in the longitudinal direction Z, the twist angle (winding angle) of the inner layer unit Uin and the twist angle (winding angle) of the outer layer unit Uout were considered to be substantially equal. 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.

Table 1 is a table summarizing the results of measuring the scalar amounts L, Lin, and Lout at positions arranged at approximately equal intervals in the longitudinal direction Z of the optical fiber assembly 1 according to Example 1. More specifically, the measurement of the scalar amount L and the like was performed for the reversal region 41 and the rotation region 42 included in four continuous cycles (twisting pitches) 30 in the longitudinal direction Z. As shown in FIG. FIG. 7 is a diagram showing Table 1 as a graph. In Table 1 and FIG. 7, each of the nine reversal regions 41 included in the measurement target is called a first reversal region to a ninth reversal region in order in the +Z direction. Similarly, each of the eight rotation areas 42 is called a first rotation area to an eighth rotation area.

The measurement of the scalar quantity L and the like at each position was performed by photographing the cross section of the optical fiber assembly 1 at regular intervals in the longitudinal direction Z and tracing the images obtained by the photographing on the xy plane. . More specifically, the measurement of the scalar quantity L and the like was performed in the following procedure. That is, light is incident on predetermined optical fibers 11 of the intermittent fixing tape core wire 10 (optical fiber unit U), and how the optical fiber unit U including the optical fiber 11 that propagates the incident light is twisted. was analyzed to confirm the winding angle of each intermittent fixing tape core wire 10 (optical fiber unit U), and to discriminate between the reversal region 41 and the rotation region 42 . After that, the optical fiber assembly 1 was hardened with an epoxy resin and cut at each position in the longitudinal direction Z. After polishing the hardened optical fiber assembly 1 so that the cross section was clear, 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, and the scalar amount L and the like were measured. Alternatively, the optical fiber cable 100 may be cut at each position in the longitudinal direction Z after the optical fiber assembly 1 is fixed with epoxy resin. 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 Z of the optical fiber cable 100 and sucking the epoxy resin from the other end. .

As can be seen from Table 1, in the optical fiber assembly 1 according to Example 1, the average value of the scalar amounts L in all the inversion regions 41 is larger than the average value of the scalar amounts L in all the rotation regions 42 . Also, as can be seen from FIG. 7, the scalar quantity L in the inversion region 41 is the scalar quantity L in one of the two rotation regions 42 adjacent to the inversion region 41 and the scalar quantity L in the other of the two rotation regions 42 is greater than at least one of L and That is, the scalar amount L in the Nth inversion area 41 is greater than at least one of the scalar amount L in the (N−1)th rotation area 42 and the scalar amount L in the Nth rotation area 42 . In other words, the scalar quantity L does not become minimum in the inversion region 41 .

Also, as can be seen from FIG. 7, the scalar amount L of the second inverted area is larger than both the scalar amount L of the first rotated area adjacent to the second inverted area and the scalar amount L of the second rotated area. Herein, a reversal having a scalar quantity L that is greater than the scalar quantity L in one of the two rotational regions 42 adjacent in the longitudinal direction Z and the scalar quantity L in the other of the two rotational regions 42 The region 41 may be particularly referred to as a maximum inversion region 41M. As can be seen from FIG. 7, in the optical fiber assembly 1 according to Example 1, the four inversion regions 41 of the second inversion region, the sixth inversion region, the seventh inversion region, and the eighth inversion region are the maximum inversion regions. 41M. Also, the number (four) of the maximum inversion regions 41M is ⅓ or more of the number (nine) of the inversion regions 41 .

FIGS. 8A to 8D are diagrams showing vectors GU, GUin, and GUout, respectively, for two rotation regions and two flip regions. The four regions shown in FIGS. 8A to 8D are continuous in the longitudinal direction Z in the order of the rotation region shown in FIG. 8A, the reversal region shown in FIG. 8B, the rotation region shown in FIG. 8C, and the reversal region shown in FIG. 8D. ing. In addition, in FIGS. 8A and 8C, the arrow indicated by symbol T indicates the direction in which a plurality of intermittently fixed tape core wires are twisted in the rotation region, that is, the direction in which each optical fiber unit (intermittently fixed tape core wire) rotates ( winding direction).

As can be seen from FIGS. 8A to 8D, the vector GUin and the vector GUout point in substantially the same direction in the inversion area. More specifically, the angle formed by vector GUin and vector GUout is 90° or less.

In order to change the collapsed state of the intermittently fixed fiber ribbon 10 so that the above-described relationship of the scalar quantity L and the vectors GUin and GUout is established, the following method may be used in the manufacturing process of the optical fiber assembly 1. Used. In other words, the vector GU in the reverse region 41 is the vector GU in one of the two rotational regions 42 adjacent to the reverse region 41 in the longitudinal direction Z, and the vector GU in the two rotational regions 42 adjacent to the reverse region 41 in the longitudinal direction Z. In order to make it different from the vector GU in the other, the technique shown below is used.
The first method is to change the tension applied to the optical fiber units U and the intermittently fixed tape core wires 10 with time in the process of twisting the optical fiber units U and the intermittently fixed tape core wires 10 in an SZ shape. . A second technique is to temporally change the rotation speed of battens used when the optical fiber units U and the intermittently fixed fiber ribbons 10 are twisted together in an SZ shape. A third method is to determine 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 optical fiber unit U and the intermittent fixing tape core wire 10 are inserted. It is a method to make it different. 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 U having different numbers of cores adjacent to each other. It should be noted that 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-described relationships regarding the scalar quantity L, the vectors GUin, and GUout can be manufactured. good. Also, some of the methods described above may be used in combination.

(Example 2)
As an optical fiber assembly 1 and an optical fiber cable 100 according to Example 2, an optical fiber assembly and an optical fiber cable of 288 fibers according to the above embodiment were produced. The optical fiber assembly 1 according to Example 2 had 24 intermittently fixed tape core wires 10 . Each intermittent fixing tape core wire 10 contained 12 optical fibers 11 . Moreover, the optical fiber assembly 1 does not have the bundle material 20, and is bundled by twisting 24 intermittently fixed tape core wires 10 in an SZ shape. In other words, the intermittent fixing tape cable core 10 did not form the optical fiber unit U. 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.

Table 2 is a table summarizing the results of measuring the scalar amount L for each position arranged at approximately equal intervals in the longitudinal direction Z of the optical fiber assembly 1 according to Example 2. More specifically, the measurement of the scalar amount L and the like was performed for the reversal regions 41 and the rotation regions 42 included in five consecutive cycles (twisting pitches) 30 in the longitudinal direction Z. FIG. 9 is a diagram showing Table 2 as a graph. In Table 2 and FIG. 9, each of the 10 reversed regions 41 included in the measurement target is called a first reversed region to a tenth reversed region in order in the +Z direction. Similarly, each of the 11 rotation areas 42 is called a first rotation area to an 11th rotation area. The details of the method for measuring the scalar quantity L and the like were the same as those in the first embodiment.

As can be seen from Table 2, even in Example 2, in which the intermittent fixing tape core wire 10 does not constitute the optical fiber unit U, the average value of the scalar amount L in all the inversion regions 41 is It is larger than the average value of the scalar quantity L in all rotation areas 42 .

Moreover, as can be seen from FIG. 9, in the optical fiber assembly 1 according to Example 2, the first inversion region, the second inversion region, the third inversion region, the fourth inversion region, the seventh inversion region, and the tenth inversion region The inversion area corresponds to the maximum inversion area 41M. Also, the number (six) of the maximum inversion regions 41M is ⅓ or more of the number (ten) of the inversion regions 41 .

Next, the operation of the optical fiber assembly 1 configured as above will be described.

Conventionally, an optical fiber cable (optical fiber assembly) having a plurality of optical fiber units collectively covered with a jacket is known. In such an optical fiber cable, when bending occurs or when the jacket shrinks in a low-temperature environment, strain may concentrate on a specific intermittently fixed tape core wire or optical fiber. Such strain concentrations have sometimes resulted in an increase in the maximum transmission loss of the fiber optic cable (optical fiber assembly). In addition, the concentration of strain on a specific intermittently fixed tape core wire (optical fiber) as described above causes the collapse of the cross-sectional shape of the optical fiber cable (optical fiber assembly), that is, the optical fiber unit (intermittently fixed tape core wire). This is particularly likely to occur when the state is constant over a long period of time. In other words, concentration of strain on a specific intermittently fixed tape core wire is particularly likely to occur when the same collapsed state continues for a long section.

On the other hand, in the optical fiber assembly 1 according to the present embodiment, the average value of the scalar quantities L in all the reversal regions 41 is larger than the average value of the scalar quantities L in all the rotation regions 42 . That is, the cross-sectional shape of the optical fiber assembly 1 , that is, the collapsed state of the intermittently fixed tape core wires 10 differs between the reversal region 41 and the rotation region 42 . Therefore, the collapsed state of the intermittently fixed optical fiber ribbon 10 is unlikely to be constant in the longitudinal direction Z, and concentration of strain on a specific intermittently fixed optical fiber ribbon 10 or optical fiber 11 can be suppressed. Thereby, an increase in the maximum transmission loss of the optical fiber assembly 1 can be suppressed.

As described above, the optical fiber assembly 1 according to the present embodiment includes a plurality of intermittently fixed portions including a plurality of optical fibers 11 and a plurality of fixing portions 12 for intermittently fixing the plurality of optical fibers 11 in the longitudinal direction Z. A forward twisted portion 31 having a tape core wire 10, in which a plurality of intermittently fixed tape core wires 10 are twisted together, and a reverse twisted portion 32 in which a plurality of intermittently fixed tape core wires 10 are twisted in a direction opposite to the normal twisted portion 31. and has an SZ twist structure in which the period 30 including and is repeated in the longitudinal direction Z, the dimension of the period 30 in the longitudinal direction Z is P, the dimension in the longitudinal direction Z is P / 4, and A region whose center is located at the boundary B between the normal twisted portion 31 and the reverse twisted portion 32 is called a reversed region 41, and a region located between the reversed regions 41 in the longitudinal direction Z is called a rotated region 42. In the cross section, Let M be the midpoint of two optical fibers 11 located at both ends of one of the plurality of intermittently fixed tape core wires 10, and let G be the center of gravity. is an end point, GU is a vector obtained by synthesizing the vector MG with respect to all the intermittently fixed fiber ribbons 10, and the magnitude of the vector GU is a scalar quantity L, a scalar in all the inversion regions 41 The average value of the quantity L is greater than the average value of the scalar quantity L in all rotation regions 42 .

With this configuration, it is possible to suppress concentration of strain on a specific intermittently fixed tape core wire 10 or optical fiber 11 and suppress an increase in the maximum transmission loss of the optical fiber assembly 1 .

In addition, the scalar quantity L in the reverse region 41 is the scalar quantity L in one of the two rotational regions 42 adjacent to the reverse region 41 in the longitudinal direction Z, and the scalar quantity L in the other of the two rotational regions 42 adjacent to the reverse region 41 and at least one of the scalar quantity L. According to this configuration, in the longitudinal direction Z of the optical fiber assembly 1, the condition of intermittent fixing tape core wires 10 changes more frequently. Therefore, concentration of strain on the specific intermittent fixing ribbon 10 or optical fiber 11 can be more reliably suppressed, and an increase in the maximum transmission loss of the optical fiber assembly 1 can be more reliably suppressed.

In addition, the plurality of inversion regions 41 includes at least one maximum inversion region 41M, and the scalar amount L in the maximum inversion region 41M is a scalar value in one of the two rotation regions 42 adjacent to the maximum inversion region 41M in the longitudinal direction Z. It may be larger than both the quantity L and the scalar quantity L in the other of the two rotation regions 42 adjacent to the maximum inversion region 41M. According to this configuration, it is possible to greatly change the collapsed state of the intermittently fixed fiber ribbon 10 in the maximum inversion region 41M. Therefore, concentration of strain on the specific intermittent fixing ribbon 10 or optical fiber 11 can be more reliably suppressed, and an increase in the maximum transmission loss of the optical fiber assembly 1 can be more reliably suppressed.

Also, the number of maximum inversion regions 41M may be ⅓ or more of the number of inversion regions 41 . According to this configuration, it is possible to more reliably suppress concentration of strain on the specific intermittently fixed tape core wire 10 and the optical fiber 11, and to further reliably suppress an increase in the maximum transmission loss of the optical fiber assembly 1. can.

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.

In addition, the plurality of optical fiber units U includes a plurality of outer layer units Uout located on the outer periphery of the optical fiber assembly 1 and at least one or more inner layer units Uin surrounded by the plurality of outer layer units Uout. Let GUin be a vector obtained by synthesizing MG for all of the plurality of intermittently fixed ribbon fibers 10 included in the inner layer unit Uin, and let GUin be a vector obtained by synthesizing MG for all of the plurality of intermittently fixed ribbon fibers 10 included in the plurality of outer layer units Uout. When the vector is GUout, the angle formed by the vector GUin and the vector GUout in the inversion area 41 may be 90° or less. According to this configuration, an increase in the maximum transmission loss of the optical fiber assembly 1 can be suppressed more reliably.

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 .

Further, in the method for manufacturing the optical fiber assembly 1 according to the present embodiment, the vector GU in the reversal region 41 is the vector GU in one of the two reversal regions 42 adjacent to the reversal region 41 in the longitudinal direction Z, and the vector GU in the reversal region 41 and the vector GU in the other of the two adjacent rotation regions 42 are made different from each other. According to this configuration, it is possible to manufacture the optical fiber assembly 1 that suppresses an increase in maximum transmission loss.

It should be noted that the technical scope of the present invention is not limited to the above embodiments, and various modifications can be made without departing from the gist of the present invention.

For example, the optical fiber assembly 1 may have inclusions (not shown) such as PP yarns and water absorbing polymers. The inclusion may be provided between the adjacent optical fiber units U, or may be provided between the adjacent intermittently fixed tape core wires 10 . When the optical fiber assembly 1 has the above inclusions, the shape of the optical fiber assembly 1 is more likely to be deformed. Therefore, an increase in the maximum transmission loss of the optical fiber assembly 1 can be suppressed more reliably.

Also, the number of optical fiber units U included in the optical fiber assembly 1 may be 11 or less, or may be 13 or more. Further, the number of the intermittently fixed fiber ribbons 10 included in each optical fiber unit U may be two or more and five or less, or may be seven or more. Further, the number of optical fibers 11 included in each intermittent fixing tape core wire 10 may be 2 or more and 11 or less, or may be 13 or more.

Also, the number of maximum inversion regions 41M included in the optical fiber assembly 1 does not have to be 1/3 or more of the number of inversion regions 41. Alternatively, the optical fiber assembly 1 may not have the maximum inversion region 41M.

In addition, all configurations other than the optical fiber assembly 1, such as the jacket 110, the pressure wrap 120, the tensile strength member 130, and the ripcord 140 in the above embodiment, are 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 boundaries B between the normal twisted portions 31 and the reverse twisted portions 32 in the inner layer units Uin and the outer layer units Uout may be the same. Further, the configuration is not limited to this, and for example, the twist angle, twist pitch, or boundary B position 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... Intermittently fixed tape core wire 11... Optical fiber 12... Fixed part 30... Twisting pitch (cycle) 41... Reversal area 41 M... Maximum reversal area 42... Rotation area Z... Longitudinal direction

Claims (8)

1. 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
   Let P be the dimension of the period in the longitudinal direction,
   A region whose dimension in the longitudinal direction is P/4 and whose center in the longitudinal direction is located at the boundary between the forward twisted portion and the reverse twisted portion is called a reversal region,
   A region located between the reversal regions in the longitudinal direction is called a rotation region,
   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,
   Let GU be a vector obtained by synthesizing the vector MG with respect to all of the plurality of intermittently fixed tape core wires, and let the magnitude of the vector GU be a scalar quantity L,
   An optical fiber assembly, wherein an average value of the scalar quantity L in all the inversion regions is larger than an average value of the scalar quantity L in all the rotation regions.
2. The scalar amount L in the inversion area is the scalar amount L in one of the two rotation areas adjacent to the inversion area in the longitudinal direction, and the scalar amount L in the other of the two rotation areas adjacent to the inversion area. 2. The optical fiber assembly according to claim 1, which is greater than at least one of said scalar quantity L and L.
3. The plurality of inversion regions includes at least one maximum inversion region,
   The scalar amount L in the maximum inversion area is the scalar amount L in one of the two rotation areas adjacent to the maximum inversion area in the longitudinal direction, 3. The optical fiber assembly according to claim 1, wherein the scalar quantity L in the other is larger than both.
4. The optical fiber assembly according to claim 3, wherein the number of said maximum inversion regions is ⅓ or more of the number of said inversion regions.
5. The plurality of intermittently fixed tape core wires form a plurality of optical fiber units,
   5. The intermittently fixed tape core wire according to any one of claims 1 to 4, wherein at least two of the plurality of intermittently fixed tape core wires are bundled in each of the plurality of optical fiber units. Optical fiber assembly.
6. The plurality of optical fiber units includes a plurality of outer layer units located on the outer periphery of the optical fiber assembly, and at least one inner layer unit surrounded by the plurality of outer layer units,
   Let GUin be a vector obtained by synthesizing the vector MG with respect to all of the plurality of intermittently fixed fiber ribbons contained in the inner layer units, and let GUin be the vector MG as all of the plurality of intermittently fixed fiber ribbons contained in the plurality of outer layer units. Let GUout be the vector synthesized for
   6. The optical fiber assembly according to claim 5, wherein an angle formed by said vector GUin and said vector GUout in said inversion region is 90[deg.] or less.
7. an optical fiber assembly according to any one of claims 1 to 6;
   and a jacket that houses the optical fiber assembly.
8. 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,
   Let P be the dimension of the period in the longitudinal direction,
   A region whose dimension in the longitudinal direction is P/4 and whose center in the longitudinal direction is located at the boundary between the forward twisted portion and the reverse twisted portion is called a reversal region,
   A region located between the reversal regions in the longitudinal direction is called a rotation region,
   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 a vector obtained by synthesizing the vector MG with respect to all of the plurality of intermittently fixed tape core wires is GU,
   The vector GU in the reversal area is divided into the vector GU in one of the two rotational areas adjacent to the reversal area in the longitudinal direction and the vector GU in the other of the two rotational areas adjacent to the reversal area. A method of manufacturing an optical fiber assembly that is different from GU and GU.

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