JP2016148709A - Optical fiber unit and optical cable - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical fiber unit capable of being housed in an optical cable reduced in diameter.SOLUTION: An optical fiber unit 1 comprises multiple paralleled coated optical fibers 10 and coupling materials 20 for coupling the multiple coated optical fibers 10. In the optical fiber unit 1, the multiple coated optical fibers 10 are fixed by the coupling materials 20 at a fixed interval between the coated optical fibers 10, and can be folded in a parallel direction of the multiple coated optical fibers 10.SELECTED DRAWING: Figure 1

Description

  The present invention relates to, for example, an optical fiber unit including a plurality of optical fiber cores and an optical cable in which the optical fiber unit is accommodated.

  For example, Patent Literature 1 discloses an optical fiber unit configured by bundling a bundled body including a plurality of optical fibers accommodated by a bundle material, and an optical fiber cable accommodating the optical fiber unit.

JP 2011-221198 A

  When an optical fiber unit as described in Patent Document 1 is accommodated in a tube-shaped jacket and an optical fiber cable is manufactured, there is a demand for reducing the diameter of the jacket. In addition, when such an optical fiber cable is bent 180 degrees (so-called cable pinching), the optical fiber accommodated in the optical fiber cable may be broken or cracked.

  An object of the present invention is to provide an optical fiber unit in which a plurality of optical fiber cores can be terminal-processed collectively and can be accommodated in a reduced-diameter optical cable, and an optical cable in which the optical fiber unit is accommodated. .

An optical fiber unit according to the present invention comprises:
A plurality of optical fiber cores arranged in parallel;
A connecting material for connecting the plurality of optical fiber core wires,
The plurality of optical fiber cores can be folded in the parallel direction of the plurality of optical fiber cores by fixing the optical fiber core wires with a predetermined interval by the connecting material.

The optical cable according to the present invention is
The above optical fiber unit;
A tube-shaped outer casing in which the optical fiber unit is folded and accommodated in the parallel direction.

  According to the present invention, it is possible to provide an optical fiber unit in which a plurality of optical fiber cores can be collectively processed at a terminal and can be accommodated in a thinned optical cable, and an optical cable in which the optical fiber unit is accommodated. Can do.

It is a perspective view which shows an example of the optical fiber unit which concerns on this embodiment. (A) is sectional drawing which shows the optical fiber core wire which comprises the optical fiber unit shown in FIG. 1, (b) is a figure which shows the refractive index distribution of the optical fiber core wire shown to (a). It is sectional drawing which shows an example of the optical cable which accommodates the optical fiber unit shown in FIG. It is a top view which shows the example of the ferrule in which the optical fiber core wire accommodated in the optical cable is inserted. It is a figure which shows the optical fiber unit which concerns on the modification of this embodiment.

[Description of Embodiment of Present Invention]
First, the contents of the embodiments of the present invention will be listed and described.
An optical fiber unit according to an embodiment of the present invention is
(1) a plurality of optical fiber cores arranged in parallel;
A connecting material for connecting the plurality of optical fiber core wires,
The plurality of optical fiber cores can be folded in the parallel direction of the plurality of optical fiber cores by fixing the optical fiber core wires with a predetermined interval by the connecting material.
According to this configuration, it is possible to provide an optical fiber unit in which a plurality of optical fiber cores can be terminal-processed collectively and can be accommodated in a reduced-diameter optical cable.

(2) It is preferable that the connecting material extends in a direction inclined with respect to a length direction of the optical fiber core wire.
According to this configuration, since there is no overlapping of the connecting members when the optical fiber unit is folded, the diameter of the folded (that is, rounded) optical fiber unit can be reduced.

(3) The diameter of each optical fiber core is 125 μm or less,
It is preferable that the diameter of the glass part of each said optical fiber core wire is 50 micrometers or less.
(4) It is preferable that the relative refractive index difference with respect to the cladding of the core of each optical fiber core wire is 1.2% or more.
According to these configurations, it is possible to provide an optical fiber unit excellent in bending resistance and handleability.

(5) It is preferable that the distance between the center lines of adjacent optical fiber cores is 1.5 to 5 times the diameter of the optical fiber core.
If the distance between the center lines is within this range, the diameter of the optical fiber unit in the folded state can be reduced, and the handleability of the optical fiber unit can be maintained.

(6) The core is preferably a GI type.
According to this structure, it is suitable as an optical fiber unit used for connection between apparatuses.

(7) The clad is preferably made of a plastic material.
According to this configuration, it is possible to provide an optical fiber unit in which the optical fiber core wire is not easily broken when the optical fiber core wire is bent in the longitudinal direction.

(8) It is preferable that the connecting material is a string, and the plurality of optical fiber core wires are fixed by being knitted by the string.
(9) It is preferable that the connection member is formed of a resin thin film that is bonded to the plurality of optical fiber core wires.
According to these configurations, it is possible to reduce the diameter of the optical fiber unit in a folded state with an easy configuration.

(10) With respect to the lateral pressure resistance of the optical fiber core wire, the increase in transmission loss is 0.5 dB when a 50 μm-diameter metal wire is pressed onto an object assembled in a grid pattern with a center interval of 150 μm with a load of 0.98 N. The following is preferable.
According to this configuration, it is possible to provide an optical fiber unit having excellent lateral pressure resistance.

Moreover, the optical cable according to the embodiment of the present invention is
(11) The optical fiber unit according to any one of (1) to (10),
It is preferable that the optical fiber unit is provided with a tube-shaped outer casing that is folded and accommodated.
According to this configuration, an optical cable with a reduced diameter can be provided.

(12) Furthermore, it is preferable to provide a tensile strength fiber accommodated in the jacket.
According to this configuration, the optical fiber core wire can be protected from the tension applied when the optical cable is laid.

(13) It is preferable that the tensile fiber is disposed between the plurality of optical fiber units accommodated in the jacket.
According to this configuration, the tensile strength fiber can be arranged by effectively using the gap in the optical cable having a reduced diameter.

(14) Connectors are connected to both ends,
In the connector, it is preferable that the plurality of optical fiber cores of one optical fiber unit are arranged in a line and inserted through the hole of the ferrule.
According to this configuration, a plurality of optical fiber core wires can be simultaneously inserted into the ferrule hole, and the connection workability to the connector is excellent.

[Details of the embodiment of the present invention]
Hereinafter, examples of an optical fiber unit and an optical cable according to the present invention will be described with reference to the drawings.
FIG. 1 is a perspective view showing an example of an optical fiber unit 1 according to the present embodiment.
As shown in FIG. 1, the optical fiber unit 1 according to the present embodiment is arranged in parallel with a plurality of optical fiber cores 10 (an example of 16 optical fibers) arranged in a line (here, for example, 16). And a tape member 20 (an example of a connecting member) for connecting these optical fiber core wires 10. The tape material 20 that connects the optical fiber cores 10 extends in a direction inclined with respect to the length direction of the optical fiber cores 10. The tape material 20 is a resin thin film that is made of, for example, an adhesive resin material and adheres to the optical fiber core wire 10. The tape material 20 may be a resin film coated with an adhesive (so-called adhesive tape or adhesive tape).

  The plurality of optical fiber cores 10 arranged in parallel are fixed to each other by a tape material 20 with a predetermined interval between the optical fiber cores 10. The plurality of optical fiber cores 10 are arranged such that the distance (pitch) between the center lines of the adjacent optical fiber cores 10 is 1.5 to 5 times the diameter of the optical fiber core 10. Is fixed. When the pitch is smaller than 1.5 times, the degree of freedom in folding the optical fiber unit 1 in the parallel direction of the optical fiber core wire 10 is limited, and the diameter of the optical fiber unit 1 in the folded state is sufficiently large. It cannot be made smaller. On the other hand, when the pitch is larger than 5 times, there is a high possibility that careless sticking between the tape members 20 will occur, and the handleability of the optical fiber unit 1 is poor. As the lower limit value of the pitch, for example, when the diameter of the optical fiber core wire 10 is 80 μm, a pitch of 125 μm is assumed. Further, as an upper limit value of the pitch, for example, when the diameter of the optical fiber core wire 10 is 50 μm, a pitch of 250 μm is assumed.

2A is a cross-sectional view showing an example of the optical fiber core wire 10 constituting the optical fiber unit 1 shown in FIG. 1, and FIG. 2B shows the refractive index distribution of the optical fiber core wire 10. FIG.
As shown in FIG. 2A, the optical fiber core wire 10 has a core 11 and a clad 12. The core 11 is made of, for example, quartz glass, and its diameter D1 is, for example, 50 μm or less. The clad 12 is made of plastic, for example, silicone having a low refractive index. The diameter D2 of the clad 12 is, for example, 125 μm or less, and preferably 80 μm or 125 μm. In this embodiment, the clad 12 is made of silicone, but an acrylate resin to which fluorine is added can also be used. Thus, the optical fiber core wire 10 in which the core 11 is made of glass and the clad 12 is made of a plastic such as silicone is called HPCF (Hard Plastic Cladd Fiber). On the other hand, an optical fiber core whose core and clad are made of glass is called AGF (All Glass Fiber). The HPCF used in the present embodiment is superior in fracture resistance compared to AGF having the same cladding diameter because the glass portion of the optical fiber core wire 10 is made thinner than AGF. That is, according to the configuration of the optical fiber core wire 10 of the present embodiment, the occurrence of breakage and cracks can be suppressed when the optical fiber core wire 10 is bent 180 degrees in the longitudinal direction.

  As shown in FIG. 2B, the core 11 of the optical fiber core wire 10 is a so-called GI (Graded Index) type, in which the refractive index gradually decreases from the center of the core 11 toward the cladding 12. It has an axisymmetric distribution shape. GI type optical fibers are widely used for inter-apparatus connection cables for short-range information communication such as LAN cables. Since the core diameter of the GI type optical fiber is larger than that of the single mode optical fiber, when connecting the optical fiber core wire and the device for connection between devices, the core and the connection destination of the signal light are connected. It becomes easy to align. Therefore, the optical fiber unit 1 of this embodiment is particularly suitable when used for inter-device connection.

  The clad 12 made of plastic is a portion having a lower refractive index than the core 11. Note that when the clad 12 is made of plastic, the refractive index of the clad 12 can be easily lowered, so that the relative refractive index difference between the core 11 and the clad 12 is larger than when the clad is made of glass. The relative refractive index difference Δ1 of the core 11 with respect to the cladding 12 is preferably 1.2% or more, for example. If the relative refractive index difference Δ1 is 1.2% or more, an increase in transmission loss of the optical fiber core wire 10 can be sufficiently suppressed.

  In the optical fiber core 10 configured in this way, an increase in transmission loss is suppressed to 0.5 dB or less. This increase in transmission loss is, for example, an increase in loss when a metal wire having a diameter of 50 μm is pressed onto an object assembled in a grid pattern with a center interval of 150 μm with a load of 100 g (0.98 N). In the present embodiment, actually, the transmission loss in the state where the mesh material is wound around the body portion of the bobbin and the optical fiber core wire 10 is wound around the bobbin body with the winding tension of 100 g (0.98 N), When the difference from the transmission loss in a state where the fiber core wire 10 is loosely wound so as to draw a circle on a plane without being wound around the bobbin (assuming no side pressure) is measured, the increase in the transmission loss is 0.5 dB or less. It was confirmed that it could be suppressed.

FIG. 3 is a cross-sectional view showing an example of the optical cable 30 of the present embodiment.
As shown in FIG. 3, the optical cable 30 includes a plurality (here, two) of optical fiber units 1, tensile strength fibers 31, and a tubular outer sheath 32 that covers the periphery of the optical fiber units 1 and the tensile strength fibers 31. And. The optical cable 30 according to the present embodiment is used for, for example, connection between devices in a data center. Therefore, the optical cable 30 is often used with a length of 10 to 100 m, preferably 10 to 20 m.

The optical fiber unit 1 is housed in the jacket 32 in a state where the optical fiber unit 1 is folded in the parallel direction of the optical fiber core wires 10. For example, the optical fiber unit 1 may be folded so as to be wound in order from the optical fiber core 10 at one end, or may be folded in a bellows shape. In the present embodiment, two 16-fiber optical fiber units 1 are housed in the outer jacket 32, so that a 32-fiber optical cable 30 is formed.
The tensile strength fiber 31 is for protecting the optical fiber core wire 10 from the tension applied when the optical cable 30 is laid, and is composed of a large number of aramid fibers and the like. The tensile strength fibers 31 are disposed between the optical fiber units 1 accommodated in the outer jacket 32. That is, the tensile fiber 31 is stored in a gap in the outer jacket 32 of the optical cable 30.

  The tube-shaped outer jacket 32 has, for example, an outer diameter of 2.0 mm and a thickness of 0.3 mm. The jacket 32 is made of polyvinyl alcohol (PVA), polyethylene, or the like. The resin material of the outer jacket 32 is preferably a material that does not contain halogen in order to reduce environmental pollution during incineration. Moreover, it is preferable that the jacket 32 is comprised from the flame-retardant resin material. In order to constitute such a material, as the jacket 32, a material obtained by adding various flame retardants (nitrogen flame retardant, phosphorus flame retardant, etc.) to the PVA or polyethylene resin is used.

  Since the optical cable 30 of this embodiment is used for, for example, connection between devices, connectors (not shown) are connected to both ends of the optical cable 30. This connector includes a ferrule 40 shown in FIG. The ferrule 40 has a plurality of holes (openings) 41 for holding the optical fiber core wire 10 accommodated in the optical cable 30. Specifically, as shown in FIG. 4, the ferrule 40 is provided with two rows of 16 holes 41 arranged in a row. The diameter of the hole 41 is usually 125 μm. Thereby, the 16 optical fiber core wires 10 included in one optical fiber unit 1 are arranged in a line and inserted through the hole 41 of the ferrule 40. That is, the optical fiber core wires 10 of the 32-core optical cable 30 are held in the holes 41 in two rows in a row with 16 cores. In this embodiment, the said optical fiber core wire 10 is being fixed with the tape material 20 so that the width | variety between the some optical fiber core wire 10 paralleled may become fixed. As a result, a plurality of optical fiber cores 10 connected with a constant width can be inserted into the hole 41 of the ferrule 40 all at once. Therefore, the workability of connecting the optical cable 30 to the connector can be improved. In addition, according to the dimension of the ferrule 40, the diameter and arrangement | positioning of the hole 41, the number of optical fiber core wires 10, a diameter, the pitch of the adjacent optical fiber core wires 10, etc. can be changed suitably.

  As described above, the optical fiber unit 1 according to the present embodiment includes the plurality of optical fiber cores 10 arranged in parallel and the tape material 20 that connects the plurality of optical fiber cores 10. The plurality of optical fiber cores 10 are fixed to each other by a tape material 20 with a predetermined interval, and the optical fiber unit 1 can be folded in the parallel direction of the optical fiber cores 10. It is. In such an optical fiber unit 1, a plurality of optical fiber cores 10 are fixed by a tape material 20 so that the relative positions of the optical fiber cores 10 in the parallel direction do not shift. Therefore, it is possible to perform terminal processing for a plurality of optical fiber cores 10 in a lump, and to insert them into the multi-core ferrule 40 all at once.

  When the periphery of a plurality of optical fiber cores is fixed with a resin or the like to form a so-called tape core (ribbon), the outer shape of the tape core is fixed. When such a flat tape core is housed in a tube-shaped outer casing, a large gap is formed around the flat tape core in the inner space of the outer casing having a circular cross section. On the other hand, the optical fiber unit 1 according to the present embodiment can be folded (rounded) freely so that the diameter of the optical fiber core wire 10 folded in the parallel direction can be reduced. It can be accommodated in the optical cable 30 having a diameter smaller than that of the core wire.

  Further, in the present embodiment, when the optical cable 30 in which the optical fiber unit 1 is housed is bent 180 degrees, the optical fiber core wires 10 overlap in a number of rows at the bent portion. When the optical fiber core wire 10 overlaps at the bent portion, the probability of breakage increases. However, in this embodiment, the glass portion of the optical fiber core wire 10 is reduced to 50 μm or less and the core 11 has a relative refraction with respect to the cladding 12. The rate difference Δ1 is set to 1.2% or more. Therefore, even when the optical cable 30 is bent 180 degrees and held for 1 minute, the optical fiber core wire 10 in the optical cable 30 is not broken, and the bending resistance is very excellent.

  The optical fiber unit 1 according to the present embodiment is composed of an optical fiber core wire 10 having a diameter of 125 μm or less. Since the diameter of the hole 41 of the ferrule 40 into which the optical fiber core wire 10 is inserted is usually 125 μm, the optical fiber core wire 10 is removed from the ferrule 40 without removing the outer layer of the optical fiber core wire 10 (for example, the plastic cladding 12). Can be inserted into the hole 41.

  In the present embodiment, the tape material 20 extends in a direction inclined with respect to the length direction of the optical fiber core wire 10. Thereby, when the optical fiber unit 1 is folded, the tape material 20 does not overlap in the parallel direction of the optical fiber core wires 10. Therefore, since the diameter of the optical fiber unit 1 in a folded (that is, rounded) state can be reduced on a surface orthogonal to the longitudinal direction of the optical fiber core wire 10, a tube shape that accommodates the optical fiber unit 1 is used. The diameter of the outer cover 32 can be further reduced.

  In the present embodiment, the distance (pitch) between the center lines of the adjacent optical fiber cores 10 is not less than 1.5 times and not more than 5 times the diameter of the optical fiber core wire 10. When the parallel pitch of the optical fiber cores 10 is within this range, the diameter of the optical cable 30 in which the optical fiber unit 1 is accommodated can be reduced, and the handleability of the optical fiber unit 1 can be maintained.

  In the present embodiment, the clad 12 is made of a plastic material. Thereby, since the glass part of the optical fiber core wire 10 is reduced in diameter, the optical fiber core wire 10 is resistant to bending and is not easily broken. In addition, since the relative refractive index difference between the core 11 and the cladding 12 is larger than when the cladding is made of glass, an increase in transmission loss can be suppressed even if the optical fiber core wire 10 is bent.

  In the present embodiment, the optical cable 30 is formed by folding the optical fiber unit 1 described above and accommodating the optical fiber unit 1 in a tube-shaped outer jacket 32. Thereby, the clearance gap in the jacket 32 can be decreased and the optical cable 30 can be reduced in diameter.

  Furthermore, in this embodiment, the tensile strength fiber 31 is arrange | positioned between the some optical fiber units 1 accommodated in the jacket 32. FIG. The tensile strength fibers 31 can be accommodated by effectively using the gaps in the jacket 32 of the optical cable 30.

  While the invention has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention. In addition, the number, position, shape, and the like of the constituent members described above are not limited to the above-described embodiments, and can be changed to a number, position, shape, and the like that are suitable for carrying out the present invention.

In the said embodiment, although the tape material 20 is used as a connection material, it is not restricted to this example. For example, as shown to Fig.5 (a), it is good also as a structure which uses the string 20A as a connection material, fixes the some optical fiber core wire 10 with the string 20A, and produces the optical fiber unit 1A. Even when the cord 20A is used, it is preferable that the plurality of optical fiber cores 10 arranged in parallel are knitted by the cord 20A so that the relative position between the optical fiber cores 10 is not shifted. As shown in FIG. 5B, the optical fiber 30 </ b> A is manufactured by housing the optical fiber unit 1 </ b> A fixed by the string 20 </ b> A together with the tensile fiber 31 in the outer jacket 32.
In addition, it is good also as a structure which couple | bonds the optical fiber core wires 10 mutually, for example in the location corresponded to the tape material 20 on the parallel optical fiber core wire 10 by thinly apply | coating and hardening an ultraviolet curable resin.
Also with these configurations, it is possible to easily reduce the diameter of the optical cable.

  In the above embodiment, the core 11 is made of glass, and the cladding 12 is made of an HPCF optical fiber core 10 made of plastic such as silicone. However, the present invention is not limited to this example. As the optical fiber core, not only the core but also the AGF in which the clad is made of glass, and the glass portion (cladding diameter) of the optical fiber core can be employed. If the glass portion (cladding diameter) of the optical fiber core wire is 50 μm or less, sufficient bending resistance is provided even when the optical fiber core wire is bent 180 degrees.

1: Optical fiber unit 10: Optical fiber core wire 11: Core 12: Clad 20: Tape material (an example of a connecting material)
30: Optical cable 31: Tensile fiber 32: Outer jacket 40: Ferrule

Claims (14)

A plurality of optical fiber cores arranged in parallel;
A connecting material for connecting the plurality of optical fiber core wires,
The plurality of optical fiber cores can be folded in the parallel direction of the plurality of optical fiber cores by fixing the optical fiber core wires with a predetermined interval by the connecting material. Fiber unit.   The optical fiber unit according to claim 1, wherein the connecting material extends in a direction inclined with respect to a length direction of the optical fiber core wire. The diameter of each optical fiber core is 125 μm or less,
The optical fiber unit according to claim 1 or 2, wherein a diameter of a glass portion of each optical fiber core wire is 50 µm or less.   The optical fiber unit according to any one of claims 1 to 3, wherein a relative refractive index difference with respect to a cladding of a core of each of the optical fiber cores is 1.2% or more.   The light according to any one of claims 1 to 4, wherein a distance between the center lines of adjacent optical fiber cores is 1.5 to 5 times the diameter of the optical fiber cores. Fiber unit.   The optical fiber unit according to any one of claims 1 to 5, wherein the core is a GI type.   The optical fiber unit according to any one of claims 1 to 6, wherein the clad is made of a plastic material.   The optical fiber unit according to any one of claims 1 to 7, wherein the connecting member is a string, and the plurality of optical fiber core wires are fixed by being knitted by the string.   The optical fiber unit according to any one of claims 1 to 7, wherein the connecting member is formed of a resin thin film bonded to the plurality of optical fiber core wires.   With respect to the lateral pressure resistance of the optical fiber core wire, an increase in transmission loss when a metal wire having a diameter of 50 μm is pressed on an object assembled in a grid pattern with a center interval of 150 μm with a load of 0.98 N is 0.5 dB or less. The optical fiber unit according to any one of claims 1 to 9. The optical fiber unit according to any one of claims 1 to 9,
An optical cable comprising a tube-shaped outer casing in which the optical fiber unit is folded and accommodated.   Furthermore, the optical cable of Claim 11 provided with the tensile strength fiber accommodated in the said jacket.   The optical cable according to claim 12, wherein the tensile fiber is disposed between the plurality of optical fiber units accommodated in the jacket. Connectors are connected to both ends,
The optical cable according to any one of claims 11 to 13, wherein, in the connector, the plurality of optical fiber core wires of one optical fiber unit are arranged in a line and are inserted through a hole of a ferrule.

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