JP2002231072A - Metal wire/optical fiber composite cable - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a metal wire/optical fiber composite cable that can reduce transmission loss due to bending of the optical fiber core-wire inside the cable, even if the optical fiber core-wire receives a local side pressure from the metal wire due to bending of the cable or the like. SOLUTION: The metal wire/optical fiber composite able is constructed by arranging a metal wire 12 on the surroundings of an optical fiber core-wire 11 that has applied a first covering 15 over the optical fiber 14. The optical fiber core-wire 11 is constructed by applying a first covering 15 cover the optical fiber 14 and then by applying on the outside of the first covering 15 a second covering 16 made of a flexible resin layer 17 comprised of a fluid oligomer or an elastomer having a high elasticity inside and a foaming material as a surface layer 18.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal wire / optical fiber composite cable constructed by arranging metal wires around optical fiber core wires and bundling them with a tape or the like. The present invention relates to a metal wire / optical fiber composite cable in which an optical fiber is not affected by local side pressure from a metal wire due to bending or the like.

[0002]

2. Description of the Related Art An optical fiber comprises a high refractive index portion called a core and a low refractive index portion called a cladding, and has a concentric structure in which the core is surrounded by the cladding. In this state, the surface of the optical fiber is easily damaged and the mechanical strength is low. Therefore, a primary coating is applied on the optical fiber to form an optical fiber core. Such an optical fiber core is used in many fields as an information communication line because it can perform long-distance transmission and can essentially perform noise-free communication and transmission of a large amount of information.

[0003] With the spread of such optical fiber cores, the number of cases in which a metal wire for supplying power and an optical fiber core for transmitting an optical signal are combined has been increasing.
For example, in an automobile wire harness, a metal wire and an optical fiber core are easily bundled using a tape or the like,
It is configured as a metal wire / optical fiber composite cable. This metal wire / optical fiber composite cable has a configuration as shown in FIG. That is,
The metal wire / optical fiber composite cable 1 is arranged around the optical fiber core 2, a plurality of metal wires 3 are attached around the optical fiber core 2, and tightly bundled by a bundle member 4 such as tape. Have been.

An optical fiber core wire 2 of the metal wire / optical fiber composite cable 1 is formed by applying a thermosetting resin to an optical fiber 2A having a concentric structure in which a core is surrounded by a clad to form a primary coating 2B. It is configured. Also,
The bundling member 4 bundles the optical fiber core wire 2 and a plurality of metal wires 3. The bundling member 4 includes a core tube into which an optical fiber is inserted, an insulated conductor extending along the side surface of the core tube, and a pair of insulated sheaths (for example, JP-A-10-247427) and an optical fiber core. There is a tape or the like which is wound around the wire with a plurality of metal wires 3 attached to the wire 2. The conventional metal wire / optical fiber composite cable 1 shown in FIG. 3 is formed by tightly wrapping a tape around an outer periphery.

[0005]

A conventional metal wire / optical fiber composite cable 1 as shown in FIG. 3 in which a plurality of metal wires 3 are tightly bundled around such an optical fiber core wire 2 is shown. As shown in FIG. 4, a local pressure load A is applied to the metal wire / optical fiber composite cable 1 from the outside.
Is applied to the optical fiber core wire 2 via the surrounding metal wire 3, a local lateral pressure load is further applied, and while the light propagates through the optical fiber at the portion receiving the lateral pressure load, , A transmission loss occurs.

Further, in the conventional metal wire / optical fiber composite cable 1, if a local portion of the metal wire / optical fiber composite cable 1 is bent and routed, as shown in FIG. The optical fiber core wire 2 is pressed by the bent portion of the metal wire 3 arranged in the above. That is, the optical fiber core wire 2 is a bent portion of the metal wire / optical fiber composite cable 1, and the local lateral pressure loads B, C, and B due to the bending of the metal wire 3 disposed around the optical fiber core wire 2.
D and E, transmission loss occurs in which the intensity of the light becomes weaker while the light propagates through the optical fiber at the portion receiving the lateral pressure loads B, C, D and E.

Further, when the metal wire / optical fiber composite cable 1 is transported to a place to be used after being manufactured, or routed, etc., the cable is often repeatedly bent and stretched. When such a cable is repeatedly bent and stretched, the metal wire / optical fiber composite cable 1 becomes as shown in FIG.
As shown in FIG.
Remains. In the conventional metal wire / optical fiber composite cable 1, a bending component remains in such bent portions 5 and 6, and local bending due to bending of the metal wire 3 disposed around the optical fiber core wire 2. Side pressure load B, C, D, E
Then, a transmission loss occurs in which the intensity of the light becomes weaker while the light propagates through the optical fiber at the portion receiving the lateral pressure loads B, C, D, and E.

As shown in FIG. 7, when the bending radius is smaller than 16 mm, the transmission loss (d) with respect to the bending radius (mm) when the optical fiber 2 is bent.
B) is remarkably increased, and the bending radius is about 0.
A transmission loss of 07 dB occurs, and a transmission loss of about 0.45 dB occurs at a bending radius of 10 mm. On the other hand, in the case of the composite cable (the conventional metal wire / optical fiber composite cable 1 as shown in FIG. 3), a transmission loss of about 0.14 dB has already occurred at a bending radius of 20 mm, and the bending radius is small. At 15 mm, a transmission loss of about 0.27 dB occurs, and at a bending radius of 10 mm, a transmission loss of about 0.8 dB occurs. The data of the transmission loss (dB) with respect to the bending radius (mm) of the optical fiber core 2 is extracted from the 2000 IEICE General Conference B-10-35. The transmission loss (dB) data for the bending radius (mm) of the composite cable is obtained by bending the conventional metal wire / optical fiber composite cable 1 as shown in FIG. ) Was determined by experiment.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a metal capable of reducing transmission loss due to bending of an optical fiber core in a cable even when the optical fiber core receives local side pressure from the metal wire due to bending of the cable or the like. It is an object of the present invention to provide a wire / optical fiber composite cable.

[0010]

According to a first aspect of the present invention, there is provided a composite metal wire / optical fiber cable according to the first aspect of the present invention, wherein a metal wire is provided around an optical fiber having a primary coating on an optical fiber. Wherein a primary coating is applied to the optical fiber, and a surface layer made of a foam material is provided outside the primary coating, and a flowable oligomer is provided inside. Alternatively, it is formed by applying a secondary coating made of a flexible resin layer made of an elastomer having a high elastic modulus. With such a configuration, according to the first aspect of the present invention, even if the optical fiber core receives local side pressure from the metal wire due to the bending of the cable or the like, the optical fiber core in the cable is bent. Transmission loss can be reduced.

In order to achieve the above object, a metal wire / optical fiber composite cable according to a second aspect of the present invention has a surface layer having a thickness of a primary coated optical fiber core diameter of 2.2.
mm, it is 0.15 mm to 0.25 mm. With this configuration, according to the second aspect of the present invention, even when the optical fiber core is subjected to local side pressure from the metal wire due to bending of the cable or the like, the optical fiber core is made of a fluid oligomer or an elastomer having a high elastic modulus. The secondary coating made of a flexible resin layer can sufficiently retain the shape.

According to a third aspect of the present invention, there is provided a composite metal wire / optical fiber cable according to the third aspect, wherein the thickness of the flexible resin layer is adjusted to a primary coated optical fiber core diameter of 2.2 mm. On the other hand, it is 0.4 mm to 0.8 mm.

According to the above construction, a third aspect is provided.
According to the invention described in the above, even if the optical fiber core receives local side pressure from the metal wire due to bending of the cable,
Lateral pressure due to bending of the optical fiber core in the cable can be sufficiently reduced.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a metal wire / optical fiber composite cable according to the present invention will be described below. FIG. 1 shows an embodiment of a metal wire / optical fiber composite cable according to the present invention.

In the figure, a metal wire / optical fiber composite cable 10 is arranged around an optical fiber core 11,
A plurality of metal wires 12 are attached around the optical fiber core 11 and tightly bound by a tape 13 as a binding member. An optical fiber core wire 11 of the metal wire / optical fiber composite cable 10 has an optical fiber 14 having a concentric structure in which a core is surrounded by a clad, and a primary material made of a thermosetting resin is provided around the optical fiber 14. A coating 15 is coated, and a secondary coating 16 is coated on the primary coating 15. The optical fiber core 11 targeted here has a core diameter of the optical fiber 14 of not very small (about 9 μm), but 200 μm.
m HPCF (hard polymer clad fiber)
Or POF (plastic optical fiber) of about 1000 μm.

The secondary coating 16 comprises a flexible resin layer 17 and a surface layer 18 made of a foam material. The flexible resin layer 17 is made of a fluid oligomer or an elastomer having a high elastic modulus. The fluid oligomer constituting the flexible resin layer 17 is a polymer having a low degree of polymerization and having a characteristic property that the material is freely deformed by a relatively small force and causes fluidity. As the fluid oligomer, there are a polyester type and an acrylic type. Then, the fluid oligomer is coated by optimizing the molecular weight and temperature conditions and the like so that the primary coating of the optical fiber can be coated with a predetermined thickness. Further, the elastomer constituting the flexible resin layer 17 is a polymer material having rubber-like elasticity at room temperature, and has a property of causing a considerable deformation under a small stress and rapidly returning to the original shape from the deformation. Things. As this elastomer, a higher degree of polymerization than an oligomer, a thermoplastic elastomer which is an elastic material crosslinked by a physical bond (microcrystal, ionic crystal, hydrogen crystal), not a partially crosslinked product or a covalent bond, is commercially available. (E.g., polyester elastomer Pelprene, manufactured by Toyobo Co., Ltd.).

The surface layer 18 is made of a foam material. This foaming material is configured by using polyethylene or polyvinyl chloride as a polymer, mixing a decomposable foaming agent into the polymer, and foaming. As the decomposition type foaming agent, azodicarbonamide (H ₂ N.CO.N: N.
Azo compounds such as CO.NH ₂ ) and sulfonyl hydrazide. The foaming ratio of the surface layer 18 may be several hundred percent or more.

In manufacturing the optical fiber core 11, a surface layer is formed by mixing a polymer with a decomposable foaming agent and heating it to an appropriate temperature (16.
After heating to 0 ° C. to 200 ° C.), the fiber is coated (extrusion foaming method) in substantially the same manner as in conventional extrusion molding, and the flexible resin layer 17 is similarly coated by an extruder. When coating the flexible resin layer 17 with an oligomer having high fluidity, it is necessary to optimize the molecular weight, temperature conditions, and the like so that the coating can be performed with a predetermined thickness. Therefore, in manufacturing the optical fiber core 11, two layers are covered by double extrusion.

The thickness of each of the flexible resin layer 17 and the surface layer 18 must be large enough to alleviate the side pressure caused by bending, and the fluidity of the optical fiber having a primary coating diameter of 2.2 mm is high. The thickness of the oligomer layer is about 0.4 to 0.8 mm,
An appropriate value is a thickness of the surface layer of 0.15 mm to 0.25 mm. In addition, a general plastic optical fiber (PO
In F) and hard polymer clad fiber (HPCF), the diameter up to the primary coating is 2.2 mm to 2.3 mm.

The optical fiber core 11 constructed as described above
Can absorb and alleviate most of the applied side pressure by the flexible resin layer 17 made of a fluid oligomer or an elastomer having a high elastic modulus, and the surface layer 18 acts to keep the shape of the flexible resin layer 17. ing. This optical fiber core 1
In the configuration of the first secondary coating, as the thickness of the flexible resin layer 17 and the surface layer 18 increases, the influence of microbending can be reduced.

The transmission loss includes a transmission loss caused by bending of the optical fiber 14 itself and a transmission loss caused by lateral pressure on the metal wire 12 due to bending or the like.
Is large (on the order of several cm) due to microbending (on the order of several mm). Therefore, the transmission loss targeted in the present embodiment is the light generated by the side pressure from the metal wire 12. Fiber 1
4 is mainly based on the modification.

In the present embodiment, an example of a metal wire / optical fiber composite cable having a configuration in which an optical fiber core is arranged at the center and a plurality of metal wires are attached around the optical fiber core is used. As described above, the metal wire / optical fiber composite cable may be such that the optical fiber core and a plurality of metal wires are bundled in a composite form, and the metal fiber / optical fiber composite cable is necessarily disposed around the optical fiber core. No need.

[0023]

The present application is configured as described above, and has the following effects. According to the first aspect of the present invention, it is possible to reduce the transmission loss due to the bending of the optical fiber core in the cable even when the optical fiber core receives local side pressure from the metal wire due to the bending of the cable or the like. it can.

According to the second aspect of the present invention, even when the optical fiber core is subjected to local side pressure from the metal wire due to bending of the cable or the like, the flexible resin made of a flowable oligomer or an elastomer having a high elastic modulus. The secondary coating composed of layers can sufficiently retain the shape.

According to the third aspect of the present invention, even if the optical fiber core receives a local side pressure from the metal wire due to the bending of the cable or the like, the side pressure due to the bending of the optical fiber core in the cable is sufficiently reduced. Can be eased.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an embodiment of a metal wire / optical fiber composite cable according to the present invention.

FIG. 2 is a cross-sectional configuration diagram of a secondary coating of an optical fiber core wire of the metal wire / optical fiber composite cable shown in FIG.

FIG. 3 is a perspective view of a conventional metal wire / optical fiber composite cable.

FIG. 4 is a diagram showing a state where a pressure load is externally applied to the metal wire / optical fiber composite cable shown in FIG. 3;

FIG. 5 is a view showing a state where the metal wire / optical fiber composite cable shown in FIG. 3 is pressed by the metal wire when bent.

FIG. 6 is a view showing residual bending components of the metal wire / optical fiber composite cable shown in FIG. 3;

FIG. 7 is a characteristic diagram showing an increase in bending loss of the metal wire / optical fiber composite cable shown in FIG.

[Explanation of symbols]

 10 Metal wire / optical fiber composite cable 11 Optical fiber core wire 12 Metal wire 13 Tape 14 Optical fiber 15 … Primary coating 16… Secondary coating 17… Flexible resin layer 18… Surface layer

Continued on the front page F term (reference) 2H001 DD24 FF02 2H050 BA33 BA34 BB13R BB32Q BB42R BC06 BC17 BD07 4G060 AA02 AA03 AA06 AB00 AC01 AC02 AD41 CB09 CB26 CB35 5G319 HA01 HB05 HC05 HD01 HE02 HE26

Claims (3)

[Claims] 1. A metal wire / optical fiber composite cable constituted by arranging a metal wire around an optical fiber core wire having a primary coating applied to an optical fiber, wherein the optical fiber core wire is primarily coated on the optical fiber. Metal wire / optical fiber composite cable having a surface layer made of a foaming material and a secondary coating made of a flexible resin layer made of a flowable oligomer or an elastomer having a high elastic modulus inside inside of the primary coating. . 2. The thickness of the surface layer is 0.15 mm to 0.1 mm with respect to the optical fiber core diameter 2.2 mm provided with the primary coating.
The composite metal wire / optical fiber cable according to claim 1, which is 0.25 mm. 3. The thickness of the flexible resin layer is 0.4 mm with respect to the optical fiber core diameter 2.2 mm provided with the primary coating.
The metal wire / optical fiber composite cable according to claim 1 or 2, which has a thickness of about 0.8 mm.