JP6981856B2 - Manufacturing method of optical fiber tape and intermittent connection type optical fiber tape - Google Patents

Description

The present invention relates to a method for manufacturing an optical fiber tape and an intermittently connected optical fiber tape.

Patent Documents 1 and 2 describe an optical cable using an intermittently connected optical fiber tape (intermittent fixing tape core wire) in which a plurality of optical fibers are intermittently connected. Patent Document 1 describes that one-way twisting or SZ twisting is applied to each of the intermittent fixing tape core wires, and one-way twisting or SZ twisting is applied to the entire collective core in which each intermittently connected optical fiber tape is assembled. Has been done.

In addition, Patent Document 3 describes that torque is applied to an optical fiber in the spinning process of the optical fiber for the purpose of suppressing signal dispersion (PMD) due to birefringence.

Japanese Unexamined Patent Publication No. 2013-195534 JP-A-2017-9922 Japanese Patent No. 2981088

In order to manufacture the collective core (fiber unit described later) described in Patent Document 1, a step of twisting an intermittently connected optical fiber tape and a step of assembling a plurality of twisted optical fiber tapes while twisting them are performed. become. However, conventionally, in order to twist an optical fiber tape, it has been necessary to apply a twisting force to the optical fiber tape. Therefore, when assembling a plurality of twisted optical fiber tapes, it is necessary to continue to maintain the torsional force applied to the optical fiber tapes, which complicates the manufacturing process.

An object of the present invention is to provide an optical fiber tape having a novel shape capable of simplifying a manufacturing process.

The main invention for achieving the above object is to supply a plurality of optical fibers including an optical fiber to which torsional strain is applied to a taper, and in the taper, the adjacent optical fibers are intermittently intermittent in the longitudinal direction. It is a method for manufacturing an optical fiber tape, characterized in that the optical fiber tape is twisted in a natural state without applying a twisting force by sequentially connecting the optical fiber tapes and releasing the torsional strain.

Other features of the present invention will be clarified by the description of the description and drawings described later.

According to the present invention, it is possible to provide an optical fiber tape twisted in a natural state without applying a twisting force.

FIG. 1A is a cross-sectional view of the optical cable 10 of the first embodiment. FIG. 1B is a cross-sectional view of another optical cable 10'. FIG. 2A is an explanatory diagram of a four-core intermittently connected optical fiber tape 12. FIG. 2B is an explanatory diagram of a 12-core intermittently connected optical fiber tape 12. 3A and 3B are different explanatory views of the four-core intermittently connected optical fiber tape 12 of the first embodiment. FIG. 4A is an explanatory diagram of a tape manufacturing apparatus 30 for manufacturing the intermittently connected optical fiber tape 12 of the first embodiment. FIG. 4B is an explanatory diagram of a cable manufacturing apparatus 40 for manufacturing the optical cable 10 of the first embodiment. 5A and 5B are explanatory views of the tape making device 33. FIG. 6 is an explanatory diagram of another rotation method of the fiber drum 31A. FIG. 7 is an explanatory diagram of another tape manufacturing apparatus 30 of the first embodiment. FIG. 8 is an explanatory diagram of the intermittently connected optical fiber tape 12 of the second embodiment. FIG. 9 is an explanatory diagram of the tape manufacturing apparatus 30 of the second embodiment.

At least the following matters will be clarified from the description of the specification and the drawings described later.

Supplying a plurality of optical fibers including an optical fiber to which torsional strain is applied to a taper, in the taper, adjacent optical fibers are intermittently connected in the longitudinal direction, and the torsional strain is applied. The method for producing an optical fiber tape, which comprises producing a twisted optical fiber tape, will be clarified. According to such a manufacturing method, an optical fiber tape twisted in a natural state can be manufactured.

A plurality of the optical fibers to which the torsional strain is applied in the same direction are supplied to the tape making device, and the torsional strain applied to the plurality of optical fibers is released together to release the twisted optical fiber. It is desirable to manufacture the tape. This makes the optical fiber even.

It is desirable that the optical fiber supplied to the tape making device is subjected to the torsional strain in one direction. This makes it possible to manufacture an optical fiber tape twisted in one direction in a natural state.

It is desirable that the torsional strain applied to the optical fiber is 2880 degrees or less per 1 m. Thereby, the polarization mode dispersion (PMD) can be suppressed.

It is desirable that the optical fiber supplied to the tape making device is subjected to the torsional strain in the SZ direction. This makes it possible to manufacture an SZ-twisted optical fiber tape in a natural state.

A plurality of fiber supply units for supplying the optical fiber to which the torsional strain is applied to the tape making device, and a controller for controlling each of the fiber supply units are provided, and the controller is the said of the respective optical fibers. It is desirable to synchronously control the fiber supply unit so that the inversion points of the torsional strain are supplied to the taper at the same timing. This makes it possible to manufacture an SZ-twisted optical fiber tape in a natural state.

It is desirable that the torsional strain applied to the optical fiber is 1440 degrees or less per 1 m. Thereby, the polarization mode dispersion (PMD) can be suppressed.

An intermittently connected optical fiber tape provided with a plurality of optical fibers and a connecting portion that intermittently connects the adjacent optical fibers in the longitudinal direction, and is twisted in one direction in a natural state where no twisting force is applied. It becomes clear that the intermittently connected optical fiber tape is characterized by being used. Such an intermittently connected optical fiber tape is convenient because the twisted state of the optical fiber tape can be maintained without applying a twisting force.

In the natural state, it is desirable that the twisting pitch is unidirectionally twisted within the range of 50 to 800 mm. As a result, deterioration of transmission loss can be suppressed.

An intermittently connected optical fiber tape provided with a plurality of optical fibers and a connecting portion that intermittently connects the adjacent optical fibers in the longitudinal direction, and the twist angle is set in a natural state where no twisting force is applied. An intermittently connected optical fiber tape characterized by being SZ twisted in the range of 270 to 720 degrees is revealed. Such an intermittently connected optical fiber tape is convenient because the twisted state of the optical fiber tape can be maintained without applying a twisting force, and deterioration of transmission loss can be suppressed.

In the natural state, it is desirable that the twist angle is 360 degrees or less and the SZ twist is performed. This makes it possible to improve the take-out property of the optical fiber tape at the time of intermediate branching of the optical cable.

When the twist angle is A (degrees), the distance between the inversion points in the twist direction is B (mm), and the twist pitch C is C = 360 × B / A, the twist pitch is 50 in the natural state. It is desirable that the SZ is twisted within the range of ~ 800 mm. As a result, deterioration of transmission loss can be suppressed.

=== First Embodiment ===

<Structure>
FIG. 1A is a cross-sectional view of the optical cable 10 of the first embodiment. The optical cable 10 is a so-called slotless optical cable. The optical cable 10 includes an optical fiber unit 11, a jacket 21, and a pair of tensile strength bodies 22.

The optical fiber unit 11 is a unit (optical fiber bundle) in which a plurality of twisted optical fiber tapes 12 are twisted and assembled. The plurality of optical fiber tapes 12 constituting the optical fiber unit 11 are assembled by being subjected to unidirectional twisting or SZ twisting. The optical cable 10 may have only one optical fiber unit 11 or may have a plurality of optical fiber units 11. When the optical cable 10 has a plurality of optical fiber units 11, it is desirable that each optical fiber unit 11 is identifiablely bundled by a bundle material (not shown). The configuration of the optical fiber tape 12 constituting the optical fiber unit 11 will be described later.

A pair of tensile strength bodies 22 are embedded in the outer cover 21. An accommodation space is formed in the central portion of the outer cover 21, and the optical fiber unit 11 is accommodated in the accommodation space. Other members such as ripcords may be embedded in the outer cover 21. Further, other members such as a presser roll tape and a filler may be accommodated in the accommodation space of the outer cover 21.

FIG. 1B is a cross-sectional view of another optical cable 10'. The optical cable 10'is a so-called slot type optical cable. A plurality of slots 24 (grooves) are formed in the spacer 23 of the optical cable 10', and each of the spacers 23 accommodates an optical fiber unit 11. The optical fiber unit 11 in which a plurality of twisted optical fiber tapes 12 are twisted and assembled may be used for the slot type optical cable 10'in this way.

FIG. 2A is an explanatory diagram of a four-core intermittently connected optical fiber tape 12. The right view of FIG. 2A is a cross-sectional view taken along the left side in AA and BB. FIG. 2B is an explanatory diagram of a 12-core intermittently connected optical fiber tape 12.

In the following description, each direction is defined as shown in FIG. 2A. That is, the longitudinal direction of the optical fiber tape 12 is simply referred to as the "longitudinal direction". The direction parallel to the optical fiber 13 in a state where a plurality of optical fibers 13 constituting the optical fiber tape 12 are arranged side by side (the state shown in FIG. 2A) may be referred to as a "longitudinal direction". Further, the direction in which the plurality of optical fibers 13 are lined up in the state shown in FIG. 2A is referred to as a "width direction". Further, the direction perpendicular to the tape surface of the optical fiber tape 12 in the state shown in FIG. 2A is referred to as a "thickness direction".

The intermittently connected optical fiber tape 12 is an optical fiber tape 12 in which a plurality of optical fibers 13 are connected in parallel and intermittently connected. The two adjacent optical fibers 13 are connected by a connecting portion 17. A plurality of connecting portions 17 connecting two adjacent optical fibers 13 are intermittently arranged in the longitudinal direction. Further, the plurality of connecting portions 17 of the optical fiber tape 12 are arranged two-dimensionally intermittently in the longitudinal direction and the width direction. The connecting portion 17 is formed by applying an ultraviolet curable resin as an adhesive and then irradiating it with ultraviolet rays to solidify it. The connecting portion 17 can also be made of a thermoplastic resin. The region other than the connecting portion 17 between the two adjacent optical fibers 13 is the non-connecting portion 19 (separated portion). In the non-connecting portion 19, the two adjacent optical fibers 13 are not constrained to each other. The non-connecting portion 19 is arranged in the width direction of the connecting portion 17. As a result, the optical fiber tape 12 can be rolled into a tubular shape (bundle shape) or folded, and a large number of optical fibers 13 can be accommodated at a high density.

The intermittently connected optical fiber tape 12 is not limited to the one shown in FIGS. 2A and 2B. For example, the number of cores of the optical fiber tape 12 may be changed. Further, the arrangement of the connecting portions 17 which are intermittently arranged may be changed.

3A and 3B are different explanatory views of the four-core intermittently connected optical fiber tape 12 of the first embodiment.

In the optical fiber tape 12 of the present embodiment, in the state shown in FIG. 3A (a state in which a plurality of optical fibers 13 constituting the optical fiber tape 12 are arranged in the width direction), a twisting force is applied to the optical fiber 13 in advance. In other words, in the state shown in FIG. 3A, the optical fiber 13 is preliminarily subjected to torsional strain. The optical fiber 13 to which the torsional force (torsional strain) is applied may be one of a plurality of optical fibers 13 constituting the optical fiber tape 12, two or more, or all of them. .. As the number of optical fibers 13 to which the torsional force (torsional strain) is applied in advance increases, the twist angle of the optical fiber tape 12 with respect to the amount of torsional strain of the optical fiber 13 increases, which is advantageous. Here, it is assumed that the torsional strain in one direction is applied to all the optical fibers 13 in advance. It is desirable to apply a torsional force (torsional strain) to all the optical fibers 13 in advance because the optical fibers 13 become uniform.

When releasing the torsional force (torsional strain) applied to the optical fiber 13, the optical fiber 13 is twisted about the longitudinal direction as shown in FIG. 3A. As a result, as shown in FIG. 3B, the optical fiber tape 12 is in a twisted state. In the present embodiment, a unidirectional torsional force (torsional strain) is applied to the optical fiber 13 in advance, and when the unidirectional torsional force (torsional strain) is released, the optical fiber tape 12 is released as shown in FIG. 3B. It will be twisted in one direction. When a torsional force (torsional strain) is applied to a plurality of optical fibers 13 in advance, a torsional force (torsional strain) in the same direction is applied to each optical fiber 13. As a result, the torsional force (torsional strain) applied to each optical fiber 13 can be released together, and as a result, as shown in FIG. 3B, the optical fiber tape 12 is twisted in one direction. become.

In the present embodiment, in order to maintain the state shown in FIG. 3A (a state in which a plurality of optical fibers 13 constituting the optical fiber tape 12 are arranged in the width direction), the restoration of the torsional strain applied to the optical fiber 13 is resisted. As described above, it is necessary to apply a twisting force to the optical fiber tape 12. On the contrary, when the optical fiber tape 12 is put into a natural state (a state in which no force is applied to the optical fiber tape 12), the optical fiber tape 12 is twisted in one direction as shown in FIG. 3B.

FIG. 3C is another explanatory view of the 12-core intermittently connected optical fiber tape 12 of the first embodiment. In the case of 12 cores, as in the case of 4 cores, a unidirectional torsional force (torsional strain) is applied to the optical fiber 13 in advance, and when the unidirectional torsional force (torsional strain) is released, the optical fiber tape is used. 12 is twisted in one direction. Further, as shown in FIG. 3C, when the number of cores is large (when the width of the optical fiber tape 12 is wide), the optical fiber is in a state where the optical fiber tape 12 is bent (curled) in the width direction. The tape 12 is in a twisted state. This is because, when the number of cores is large, if the optical fiber tape 12 is twisted without bending in the width direction, the outer optical fiber 13 (the optical fiber 13 at the end in the width direction) and the inner optical fiber 13 (the width direction). It is considered that this is because the difference in line length from the optical fiber 13) in the central portion of the above is widened. That is, it is considered that the optical fiber tape 12 bends (rounds) in the width direction so that the difference in line length becomes small. Further, not only when the number of cores is increased, but also when the twisting pitch of the optical fiber tape 12 becomes smaller, the optical fiber tape 12 is more likely to bend in the width direction. As shown in FIG. 3B, the "twisting pitch" is the length (mm) in the longitudinal direction until the optical fiber tape 12 is twisted 360 degrees.

When the optical fiber tape 12 is twisted in one direction in a natural state (see FIG. 3B) as in the first embodiment, the twist pitch is preferably in the range of 50 to 800 mm. If the twisting pitch exceeds 800 mm, it becomes difficult to obtain the effect of twisting the optical fiber tape 12, and the transmission loss deteriorates. On the other hand, when the twisting pitch is 50 mm or less, the amount of deformation of the optical fiber tape 12 becomes large, which makes batch fusion difficult.

As described above, in the cross section of the twisted optical fiber tape 12, a plurality of optical fibers 13 may be arranged in a horizontal row (sheet state) as shown in FIG. 3B, or in the width direction as shown in FIG. 3C. It may be in a curled state (bundle state). In the natural state (a state in which no force is applied to the optical fiber tape 12), even if the optical fiber tape 12 is in the form of a sheet as shown in FIG. 3B, the optical fiber is applied by applying a force in the width direction to the optical fiber tape 12. It is also possible to deform the tape 12 so that it is in a bundled state. When a plurality of twisted optical fiber tapes 12 are twisted and assembled, a force is applied to the optical fiber tape 12, so that the optical fiber tape 12 is curled or bent in the width direction and deformed into a bundled state. It will be.

<Manufacturing method 1>
FIG. 4A is an explanatory diagram of a tape manufacturing apparatus 30 for manufacturing the intermittently connected optical fiber tape 12 of the first embodiment.

The tape manufacturing apparatus 30 is an apparatus for manufacturing the intermittently connected optical fiber tape 12 shown in FIG. 3B. The tape manufacturing apparatus 30 includes a fiber supply unit 31, a tape forming apparatus 33, a taking-up apparatus 37, and a tape drum 38.

The fiber supply unit 31 is a device that supplies the optical fiber 13 to the tape making device 33. In the case of manufacturing the 12-core optical fiber tape 12, the number of fiber supply units 31 is 12. The fiber supply unit 31 of the present embodiment supplies the optical fiber 13 to the tape making device 33 in a state where a torsional force (torsional strain) is applied. The fiber supply unit 31 has a fiber drum 31A and a delivery unit 31B. The fiber drum 31A supplies the optical fiber 13 while rotating around the longitudinal direction of the optical fiber 13. A torsional force (torsional strain) is applied to the optical fiber 13 by rotating the fiber drum 31A with respect to the delivery portion 31B (rotation about the longitudinal direction). The delivery unit 31B is a device that sends the optical fiber 13 to the tape making device 33 in a state where a torsional force (torsional strain) is applied.

Each of the fiber drums of the four fiber supply units 31 rotates in the same direction with the longitudinal direction as an axis. A torsional force (torsional strain) in the same direction is applied to each optical fiber 13. This makes it possible to release the torsional strain of each optical fiber 13 together.

The tape making device 33 is a device that intermittently forms a connecting portion 17 between the optical fibers 13 to form an intermittently connected optical fiber tape 12. 5A and 5B are explanatory views of the tape making device 33. The tape making device 33 has a coating unit 34, a removing unit 35, and a light source 36.

The coating unit 34 is a device for applying a connecting material. The connecting material is, for example, an ultraviolet curable resin, and the connecting portion 17 is formed by curing the connecting material. The coating unit 34 coats the connecting material between the adjacent optical fibers 13. The coating unit 34 coats the liquid connecting material between the adjacent optical fibers 13 in the longitudinal direction by inserting the plurality of optical fibers 13 into the coating die filled with the liquid connecting material. In the present embodiment, the optical fiber 13 is inserted into the coating die in a state where a torsional force (torsional strain) is applied. Further, in the present embodiment, the optical fiber 13 is coated with a connecting material between the optical fiber 13 and the adjacent optical fiber 13 in a state where a torsional force (torsional strain) is applied.

The removing unit 35 is a device that removes a part of the connecting material coated by the coating unit 34 while leaving a part of the connecting material. The removing portion 35 has a rotary blade 351 having a recess 351A (see FIG. 5A), and rotates the rotary blade 351 according to the supply speed of the optical fiber 13. The connecting material applied by the coating portion 34 is removed by the outer edge of the rotary blade 351 but the connecting material remains in the recess 351A of the rotary blade 351. The portion where the connecting material remains is the connecting portion 17 (see FIG. 2A), and the portion from which the connecting material is removed is the non-connecting portion 19.

The light source 36 is a device that irradiates a connecting material made of an ultraviolet curable resin with ultraviolet rays. The light source 36 has a temporary curing light source 36A and a main curing light source 36B. The temporary curing light source 36A is arranged on the upstream side of the main curing light source 36B. The connecting material is temporarily cured when it is irradiated with ultraviolet rays from the temporary curing light source 36A. The temporarily cured connecting material is not completely cured, but is in a state where curing has progressed on the surface. The main curing light source 36B irradiates ultraviolet rays stronger than the temporary curing light source 36A to mainly cure the connecting material. The main-cured ultraviolet curable resin is in a state of being cured to the inside (however, the main-cured connecting material (connecting portion 17) has appropriate elasticity, and the intermittently connected optical fiber tape 12 is rolled into a cylinder. It is possible to make it into a shape).

As shown in FIG. 5B, the optical fibers 13 immediately after coming out of the coating portion 34 and the removing portion 35 are spaced apart from each other. In this state, the temporary curing light source 36A irradiates the connecting material with ultraviolet rays to temporarily cure the connecting material. After the temporary curing of the connecting material, the tape making device 33 gradually narrows the interval between the optical fibers 13 and arranges a plurality of optical fibers 13 in parallel to collect the wires in a tape shape. Since the connecting material is temporarily cured, even if the parts (separated parts) from which the connecting materials have been removed come into contact with each other, they do not have to be connected. Further, since it is before the main curing, it is possible to narrow the interval (concentration) of the optical fibers 13 even in the region connected by the connecting material. When the connecting material is main-cured by irradiating the main curing light source 36B with ultraviolet rays, the optical fiber tape 12 shown in FIG. 2A is manufactured. In the optical fiber tape 12 at this stage, the optical fibers 13 to which the torsional force (torsional strain) is applied are intermittently connected.

The take-up device 37 is a device that takes over the optical fiber tape 12 from the tape-making device 33. The taking-up device 37 takes over the optical fiber tape 12 from the tape-making device 33 while applying a twisting force to the optical fiber tape 12 so as to resist the restoration of the torsional strain applied to the optical fiber 13. Therefore, on the upstream side of the take-up device 37 (between the tape making device 33 and the take-up device 37), the optical fiber tape 12 has the width shown in FIG. 3A (the width of the plurality of optical fibers 13 constituting the optical fiber tape 12). The state of lining up in the direction) is maintained. On the other hand, the take-up device 37 sends the optical fiber tape 12 to the tape drum 38 so as to release the torsional force (torsional strain) applied to the optical fiber 13. Therefore, on the downstream side of the take-up device 37 (between the take-up device 37 and the tape drum 38), the optical fiber tape 12 is in the state shown in FIG. 3B (the state in which the optical fiber tape 12 is twisted, the optical fiber tape 12). It becomes a natural state where no twisting force is applied to the optical fiber.

The tape drum 38 is a member for winding the optical fiber tape 12. The tape drum 38 rotates about the longitudinal direction so as to release the torsional force applied to the optical fiber 13. Therefore, the optical fiber tape 12 in the state shown in FIG. 3B is wound around the tape drum 38. The tape drum 38 rotates about the longitudinal direction in synchronization with the rotation of the fiber drum 31A in order to release the torsional force applied to the optical fiber 13.

FIG. 4B is an explanatory diagram of a cable manufacturing apparatus 40 for manufacturing the optical cable 10 of the first embodiment.

The cable manufacturing apparatus 40 is an apparatus for manufacturing the optical cable 10 shown in FIG. 1A. In this embodiment, it has a plurality of tape supply units 41, a collecting device 43, an extruder 44, a cooler 45, and a cable drum 46.

The tape supply unit 41 is a device that supplies the optical fiber tape 12. In the present embodiment, the tape supply unit 41 supplies the optical fiber tape 12 in a twisted state (state shown in FIG. 3B) to the collecting device 43. The optical fiber tape 12 is supplied to the collecting device 43 from each of the plurality of tape supply units 41. That is, a plurality of twisted optical fiber tapes 12 are supplied to the collecting device 43.

The collecting device 43 is a device for twisting and collecting a plurality of twisted optical fiber tapes 12. The collecting device 43 forms an optical fiber unit 11 by twisting a plurality of optical fiber tapes 12 in one direction or in SZ, and supplies the optical fiber unit 11 to the extruder 44.

The extruder 44 is an apparatus for extruding the outer cover 21 of the optical cable 10. A tensile strength body 22 is supplied to the extruder 44 together with the optical fiber unit 11 from the tensile strength body supply unit 42. The cooler 45 is a device for cooling the outer cover 21 of the optical cable 10. The cable drum 46 is a member for winding the optical cable 10. The optical cable 10 shown in FIG. 1A is wound around the cable drum 46.

In the present embodiment, the tape supply unit 41 supplies the optical fiber tape 12 in a naturally twisted state to the collecting device 43, and the collecting device 43 is in a naturally twisted state. The optical fiber tape 12 is twisted together to form the optical fiber unit 11. Therefore, in the present embodiment, since the optical fiber tape 12 is in a twisted state in a natural state, it is not necessary to continuously apply a twisting force to the optical fiber tape 12 in order to maintain the twisted state. , The tape supply unit 41 and the collecting device 43 (or the supply path between the tape supply unit 41 and the collecting device 43) can be simplified. Since the optical fiber unit 11 is configured by twisting and assembling a plurality of twisted optical fiber tapes 12, it is possible to suppress transmission loss when the optical cable 10 is bent and to reduce the diameter of the optical cable 10. Can be planned.

In the above description, the fiber drum (drum around which the optical fiber 13 is wound) of the fiber supply unit 31 is rotated about the longitudinal direction of the optical fiber 13, so that the drum axis is about the longitudinal direction of the optical fiber 13 as the central axis. Is swirled to impart torsional strain to the optical fiber 13. However, the method of applying torsional strain to the optical fiber 13 is not limited to this. For example, as shown in FIG. 6, a torsional strain may be applied to the optical fiber 13 by making the drum axis of the fiber drum perpendicular to the rotation axis and rotating the drum axis about the rotation axis. Also in the above-mentioned tape drum 38 (see FIG. 4A), the drum axis may be rotated around a rotation axis orthogonal to the drum axis instead of rotating the drum axis about the longitudinal direction. Further, as will be described next, the method of applying torsional strain to the optical fiber 13 is not limited to the method of rotating the optical fiber drum.

<Manufacturing method 2>
FIG. 7 is an explanatory diagram of another tape manufacturing apparatus 30 of the first embodiment. Here, torsional strain is applied to the optical fiber 13 in the spinning process (drawing process).

The fiber supply unit 31 includes a preform 311, a heating furnace 312, a coating device 313, a curing device 314, and a plurality of guide rollers 315 (315A to 315D). The preform 311 is a base material (glass rod) of the optical fiber 13. The heating furnace 312 is a furnace that heats the preform 311 in order to melt and stretch the preform 311, for example, an electric furnace. The coating device 313 is a device for coating a resin on an optical fiber immediately after spinning. The optical fiber will be cooled between the heating furnace 312 and the coating device 313. The curing device 314 is a device for curing the resin coated by the coating device 313, and is, for example, an ultraviolet irradiation device. The guide roller 315 is a roller constituting the path of the optical fiber.

The first guide roller 315A arranged on the most upstream side of the plurality of guide rollers 315 is a member with which the optical fiber spun from the preform 311 first contacts. In the dotted line frame of FIG. 7, an explanatory diagram in the vicinity of the first guide roller 315A is shown. The first guide roller 315A is arranged so that the rotation axis is inclined with respect to the path of the optical fiber 13. As a result, in the first guide roller 315A, a torsional force (torque) is applied to the optical fiber 13. That is, the first guide roller 315A is a torque applying member that applies a torsional force (torque) to the optical fiber 13.

Since there is nothing in contact with the spun optical fiber on the upstream side of the first guide roller 315A, when the first guide roller 315A applies a twisting force to the optical fiber 13, immediately after being spun from the preform 311. The optical fiber (the optical fiber between the preform 311 and the first guide roller 315A) is in a twisted state. In other words, the optical fiber 13 is manufactured in a twisted state through a coating step (coating apparatus 313) and a curing step (curing apparatus 314). Torsional strain remains in the optical fiber 13 manufactured in this way.

The method of applying torsional strain to the optical fiber 13 in the spinning process (drawing process) is not limited to the method shown in FIG. 7. For example, instead of applying torque to the optical fiber 13 with the first guide roller 315A, the preform 311 is rotated about the longitudinal direction of the optical fiber 13 to cause torsional strain on the optical fiber 13 in the spinning process (drawing process). May be given.

In this way, the optical fiber 13 to which the torsional strain is applied is supplied from the fiber supply unit 31 to the tape making device 33. Then, as described above, the optical fiber 13 in a state where the torsional force (torsional strain) is applied is supplied to the tape making device 33 from the fiber supply unit 31, and in the tape making device 33, two adjacent cores are supplied. The connecting portion 17 is intermittently formed between the optical fibers 13 in the longitudinal direction.

By the way, for the purpose of suppressing polarization mode dispersion (PMD), torque may be applied to the optical fiber 13 in the spinning process (see, for example, Patent Document 3). However, even if the optical fiber tape 12 is formed by using the optical fiber 13 to which the torsional strain is applied in advance for this purpose, the torsional strain of the optical fiber 13 is released because the torsional directions of the respective optical fibers 13 are different. However, it does not become a unidirectionally twisted optical fiber tape 12 in a natural state.

When a plurality of optical fiber tapes 12 twisted in one direction are twisted to form an optical fiber unit 11 as in the present embodiment, the twist pitch of the optical fiber tape 12 (see FIG. 3B) is 800 mm or less. It is desirable to have. In order to form an optical fiber tape 12 in which the twist pitch is twisted to 800 mm or less in a natural state, light is used in the spinning process for the purpose of suppressing polarization mode dispersion (PMD: dispersion of signals by double refraction). It is necessary to set a large torsional force (torque) applied to the optical fiber 13 and set a large torsional strain applied to the optical fiber 13 in advance as compared with the case where the torque is applied to the fiber 13. On the other hand, if the torsional strain applied to the optical fiber 13 is too large, polarization mode dispersion (PMD) may become a problem. Regarding this point, the inventor of the present application has a q value of 0.070, which is a measured value of PMD, when the torsional strain (one direction) applied to the optical fiber 13 (optical fiber strand) is 2880 degrees or less per 1 m. , It was confirmed that the value was below the specified standard value (0.08 or less). Then, the inventor of the present application sets the torsional strain (one direction) applied to the optical fiber 13 (optical fiber wire) to 2880 degrees or less per 1 m, and in a natural state, the optical fiber tape twisted in one direction at 720 to 3600 degrees per 1 m. It was confirmed that 12 can be manufactured. The q value of PMD is a value based on JIS C 6870-3 (or IEC6073-1-48), and four values are randomly extracted from all the measurement data, and this is performed 100,000 times. It is a value obtained based on the normal distribution function obtained.

=== Second embodiment ===
FIG. 8 is an explanatory diagram of the intermittently connected optical fiber tape 12 of the second embodiment. Although not shown in FIG. 8, a connecting portion 17 is intermittently formed in the longitudinal direction between the two adjacent optical fibers 13. Further, the plurality of connecting portions 17 of the optical fiber tape 12 are arranged two-dimensionally intermittently in the longitudinal direction and the width direction. Further, the non-connecting portion 19 is arranged in the width direction of the connecting portion 17.

When the optical fiber tape 12 of the second embodiment is in a natural state (a state in which no force is applied to the optical fiber tape 12), the optical fiber tape 12 is twisted in the SZ direction as shown in the figure. At the portion shown by the dotted line in the figure, the twisting direction of the optical fiber tape 12 is reversed.

In the following description, the interval (mm) in the longitudinal direction of the inversion portion in the twisting direction (the portion of the dotted line in the figure) may be referred to as "inversion pitch". Further, the angle at which the optical fiber tape 12 is twisted between a certain inversion point (dotted line in the figure) and the next inversion point (between the inversion pitches) may be referred to as a "twisting angle". Further, the length (mm) in the longitudinal direction until the optical fiber tape 12 is twisted 360 degrees may be referred to as "twisting pitch". In the figure, an SZ-twisted optical fiber tape 12 with a twist angle of 360 degrees is shown. Since the twist angle may be less than 360 degrees, in the present embodiment, the twist pitch is calculated as a length (mm) corresponding to one rotation (360 degrees). Specifically, when the twist angle is A (degrees) and the inversion pitch is B (mm), the twist pitch C (mm) is calculated as C = 360 × B / A. When the twist angle is 360 degrees, the inversion pitch and the twist pitch are equal.

In the optical fiber tape 12 of the second embodiment, in a state where a plurality of optical fibers 13 constituting the optical fiber tape 12 are arranged in the width direction (sheet state), the optical fiber 13 is preliminarily subjected to torsional strain in the SZ direction. .. The optical fiber 13 to which the torsional strain is applied in the SZ direction may be one of the plurality of optical fibers 13, two or more, or all of them. Here, it is assumed that the torsional strain in the SZ direction is preliminarily applied to all the optical fibers 13.

When releasing the torsional strain applied to the optical fiber 13, the optical fiber 13 is twisted about the longitudinal direction. In the second embodiment, a torsional force (torsional strain) in the SZ direction is applied to the optical fiber 13 in advance, and when the torsional force (torsional strain) in the SZ direction is released, the torsional direction is changed at predetermined intervals in the longitudinal direction. The optical fiber 13 is twisted while inverting. As a result, in the second embodiment, as shown in FIG. 8, the optical fiber tape 12 is twisted in the SZ direction.

When a torsional force (torsional strain) is applied to a plurality of optical fibers 13 in advance, a torsional force (torsional strain) in the same direction is applied to each optical fiber 13. When a torsional force (torsional strain) in the SZ direction is applied to a plurality of optical fibers 13 in advance as in the present embodiment, the direction of the torsional strain is reversed at the same position in the longitudinal direction. As a result, the torsional force (torsional strain) applied to each optical fiber 13 can be released together, and as a result, as shown in FIG. 8, the optical fiber tape 12 is twisted in the SZ direction. become.

When the optical fiber tape 12 is SZ twisted in a natural state (see FIG. 8) as in the second embodiment, the twist angle is preferably in the range of 270 to 720 degrees, and is preferably 270 degrees to 360 degrees. It is more desirable to be within the range of degrees. When the twist angle is within this range, the transmission loss when the optical cable 10 is bent can be suppressed. If the twist angle is less than 270 degrees, it becomes difficult to obtain the effect of suppressing transmission loss. Further, if the twist angle is too large, the transmission loss may worsen, so it is desirable that the twist angle is 720 degrees or less. Further, in order to improve the take-out property of the optical fiber tape at the time of intermediate branching of the optical cable, it is more desirable that the twist angle is 360 degrees or less.

By the way, for the purpose of suppressing polarization mode dispersion (PMD), torque may be applied to the optical fiber 13 in the spinning process (see, for example, Patent Document 3). However, since the torsional strain applied to the optical fiber 13 for this purpose is small, even if the optical fiber tape 12 is formed by using such an optical fiber 13, the twist angle of the optical fiber tape 12 in a natural state is still high. , 10 to 20 degrees (the optical fiber tape 12 of the present embodiment has an extremely large twist angle as compared with this twist angle). In such an optical fiber tape 12 having a twist angle of 10 to 20 degrees, since the twist angle is less than 270 degrees, the effect of suppressing transmission loss can hardly be obtained.

When a plurality of optical fiber tapes 12 twisted in the SZ direction are twisted to form the optical fiber unit 11 as in the second embodiment, the twisting pitch of the optical fiber tape 12 (see FIG. 8) is set. It is preferably in the range of 50 to 800 mm. If the twisting pitch exceeds 800 mm, it becomes difficult to obtain the effect of twisting the optical fiber tape 12, and the transmission loss deteriorates. On the other hand, when the twisting pitch is 50 mm or less, the amount of deformation of the optical fiber tape 12 becomes large, which makes batch fusion difficult.

In order to keep the twist angle of the optical fiber tape 12 within the range of 270 to 360 degrees, light is compared with the case where torque is applied to the optical fiber 13 in the spinning process for the purpose of suppressing polarization mode dispersion (PMD). It is necessary to set a large torsional force (torque) applied to the fiber 13 and set a large torsional strain applied to the optical fiber 13 in advance. On the other hand, if the torsional strain applied to the optical fiber 13 is too large, polarization mode dispersion (PMD) may become a problem. Regarding this point, the inventor of the present application has a q value of 0.070, which is a measured value of PMD, when the torsional strain (SZ direction) applied to the optical fiber 13 (optical fiber strand) is 1440 degrees or less per 1 m. , It was confirmed that the value was below the specified standard value (0.08 or less). Further, if the torsional strain in the SZ direction in this range is applied to the optical fiber 13, the optical fiber tape 12 can be SZ twisted within a twist angle range of 270 to 360 degrees.

FIG. 9 is an explanatory diagram of the tape manufacturing apparatus 30 of the second embodiment. Also in the second embodiment, torsional strain is applied to the optical fiber 13 in the spinning process (drawing process).

Similar to the first embodiment, the fiber supply unit 31 of the second embodiment includes a preform 311, a heating furnace 312, a coating device 313, a curing device 314, and a plurality of guide rollers 315 (315A to 315D). Has. In the second embodiment, the rotation axis of the first guide roller 315A swings with respect to the path of the optical fiber 13. As a result, in the first guide roller 315A, a torsional force (torque) is applied to the optical fiber 13, and the direction of the torsional force is intermittently reversed. In the optical fiber 13 manufactured in this way, torsional strain remains and the direction of the torsional strain is reversed at predetermined intervals.

The controller 50 in the figure is a control unit that controls the tape manufacturing apparatus 30, and controls four fiber supply units 31. In the second embodiment, the controller 50 supplies the optical fiber 13 from the four fiber supply units 31 at the same supply speed, and synchronizes the first guide rollers 315A of the four fiber supply units 31 to swing. I'm letting you. In other words, in the controller 50, the torsional strains of the plurality of optical fibers 13 supplied to the taper 33 are in the same direction, and the inversion points of the torsional strains of the respective optical fibers 13 are supplied to the taper 33 at the same timing. As a result, the torque applying members (first guide roller 315A) of the four fiber supply units 31 are synchronously controlled.

In the second embodiment, the tape-making device 33 has a connecting portion 17 (and non-connecting) with the adjacent optical fiber 13 in a state where a plurality of optical fibers 13 to which a torsional force is applied in the SZ direction are lined up in the width direction. Part 19) is formed to form a sheet-shaped intermittently connected optical fiber tape 12. The taking-up device 37 takes the optical fiber tape 12 from the tape-making device 33 so as to resist the restoration of the torsional strain applied to the optical fiber 13, and releases the torsional force (twisting strain) applied to the optical fiber 13. While feeding the optical fiber tape 12 to the tape drum 38. Therefore, on the downstream side of the take-up device 37 (between the take-up device 37 and the tape drum 38), the optical fiber tape 12 is in the state shown in FIG. 8 (the state in which the optical fiber tape 12 is SZ twisted, the optical fiber tape). 12 is in a natural state where no twisting force is applied). In the second embodiment, the torsional strain is applied to the optical fiber 13 while alternately reversing, and the torsional strain applied to each optical fiber 13 reverses the direction at the same position in the longitudinal direction. Therefore, even if the tape drum 38 does not rotate about the longitudinal direction, the torsional force (torsional strain) applied to each optical fiber 13 can be released together, and as a result, FIG. 9 shows. As shown, the SZ-twisted optical fiber tape 12 is wound around the tape drum 38. As described above, in the second embodiment, the torsional force (torsional strain) applied to the optical fiber 13 can be easily released as compared with the first embodiment.

Also in the second embodiment, as described in the first embodiment, by rotating the preform 311 about the longitudinal direction of the optical fiber 13, the optical fiber 13 is twisted and strained in the spinning process (drawing process). May be given. Further, instead of applying torsional strain to the optical fiber 13 in the spinning process (drawing process), torsional force (torsional strain) may be applied to the optical fiber 13 by rotating the fiber drum 31A.

=== Others ===
The above embodiment is for facilitating the understanding of the present invention, and is not for limiting the interpretation of the present invention. It goes without saying that the present invention can be modified or improved without departing from the spirit thereof, and the present invention includes an equivalent thereof.

10 optical cables, 11 fiber optic units,
12 optical fiber tape, 13 optical fiber,
17 connected part, 19 non-connected part,
21 jacket, 22 tensile strength body,
23 spacers, 24 slots,
30 tape manufacturing equipment, 31 fiber supply unit,
31A fiber drum, 31B transmitter,
311 preform, 312 heating furnace,
313 Coating device, 314 Curing device,
315 (315A-315D) guide roller,
315A 1st guide roller,
33 Tapering device, 34 Coating part, 35 Removal part,
351 rotary blade, 351A recess,
36 light source, 36A temporary curing light source, 36B main curing light source,
37 Pick-up device, 38 Tape drum,
40 cable manufacturing equipment, 41 tape supply unit,
42 tensile strength body supply unit, 43 collecting device, 44 extruder,
45 cooler, 46 cable drum

Claims (12)

Supplying a plurality of optical fibers, including an optical fiber with torsional strain, to a taper.
In the tape making device, the adjacent optical fibers are intermittently connected in the longitudinal direction, and
A method for producing an optical fiber tape, which comprises releasing the torsional strain to produce an optical fiber tape twisted in a natural state without applying a torsional force. The method for manufacturing an optical fiber tape according to claim 1.
A plurality of the optical fibers to which the torsional strain is applied in the same direction are supplied to the tape making device.
A method for manufacturing an optical fiber tape, which comprises releasing the torsional strain applied to a plurality of the optical fibers together to manufacture a twisted optical fiber tape. The method for manufacturing an optical fiber tape according to claim 1 or 2.
A method for manufacturing an optical fiber tape, wherein the optical fiber supplied to the tape-making device is subjected to the torsional strain in one direction. The method for manufacturing an optical fiber tape according to claim 3.
A method for manufacturing an optical fiber tape, wherein the torsional strain applied to the optical fiber is 2880 degrees or less per 1 m. The method for manufacturing an optical fiber tape according to claim 1 or 2.
A method for manufacturing an optical fiber tape, wherein the optical fiber supplied to the tape-making device is subjected to the torsional strain in the SZ direction. The method for manufacturing an optical fiber tape according to claim 5.
A plurality of fiber supply units for supplying the optical fiber to which the torsional strain is applied to the tape-making device, and
It is equipped with a controller that controls each of the fiber supply units.
A method for manufacturing an optical fiber tape, wherein the controller synchronously controls the fiber supply unit so that the inversion points of the torsional strain of each optical fiber are supplied to the taper at the same timing. .. The method for manufacturing an optical fiber tape according to claim 5 or 6.
A method for manufacturing an optical fiber tape, wherein the torsional strain applied to the optical fiber is 1440 degrees or less per 1 m. With multiple optical fibers
An intermittently connected optical fiber tape provided with a connecting portion that intermittently connects between adjacent optical fibers in the longitudinal direction.
An intermittently connected optical fiber tape characterized by being twisted in one direction in a natural state where no twisting force is applied. The intermittently connected optical fiber tape according to claim 8.
An intermittently connected optical fiber tape characterized in that, in the natural state, the twisting pitch is unidirectionally twisted within a range of 50 to 800 mm. With multiple optical fibers
An intermittently connected optical fiber tape provided with a connecting portion that intermittently connects between adjacent optical fibers in the longitudinal direction.
An intermittently connected optical fiber tape characterized in that the twist angle is SZ twisted within a range of 270 to 720 degrees in a natural state where no twisting force is applied. The intermittently connected optical fiber tape according to claim 10.
An intermittently connected optical fiber tape characterized by being SZ twisted at a twist angle of 360 degrees or less in the natural state. The intermittently connected optical fiber tape according to claim 10 or 11.
The twist angle is A (degrees), the distance between the inversion points in the twist direction is B (mm), and the twist pitch C is C = 360 × B / A.
When
An intermittently connected optical fiber tape characterized in that, in the natural state, the twist pitch is SZ twisted within the range of 50 to 800 mm.

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