JP5581842B2 - Photoelectric composite cable - Google Patents

Description

  The present invention relates to a photoelectric composite cable having an electric wire and an optical fiber.

  In electronic devices such as medical devices, portable terminals, small video cameras, personal computers, and PDAs (Personal Digital Assistants), high-speed communication is required as functions become more sophisticated. For this reason, the use of an optoelectric composite cable in which an electric wire and an optical fiber are combined is performed.

  As a photoelectric composite cable, a buffer layer is provided on the outer periphery of an optical fiber, a sheath is provided on the outer periphery, an electric wire is provided outside the sheath, and a jacket is provided on the outer periphery (for example, , See Patent Document 1).

Japanese Utility Model Publication No. 62-135309

By the way, there is a possibility that the transmission loss of the optical fiber constituting the photoelectric composite cable may increase due to excessive bending or twisting. In this case, it is possible to suppress excessive bending and twisting by providing a reinforcing member such as a strength member, but this leads to an increase in diameter and increases the bending rigidity of the cable, which requires a large wiring space. .
Further, when the optoelectric composite cable is bent, the optical fiber may receive a side pressure from the electric wire arranged on the outer periphery, and the transmission loss may increase due to the side pressure.

  An object of the present invention is to provide an optical / electrical composite cable capable of suppressing external force from being applied to an optical fiber and maintaining good transmission characteristics of the optical fiber without causing an increase in diameter. .

The photoelectric composite cable of the present invention that can solve the above-mentioned problems is a photoelectric composite cable having a plurality of optical fibers and a plurality of electric wires inside the jacket,
The optical fiber is housed in a tube having a Shore D hardness of 65 or more and a thickness of 0.05 mm or more and 0.8 mm or less, the optical fibers are in contact with each other, and all the optical fibers are formed of the tube. Arranged so as to contact the inner peripheral surface, the plurality of electric wires are arranged around the tube ,
When wound on a mandrel having a diameter of 4 mm, an increase in transmission loss of light at a wavelength of 850 nm propagating through the optical fiber is 1 dB / 10 turns or less .

  In the photoelectric composite cable of the present invention, the tube is preferably formed from a tetrafluoroethylene-ethylene copolymer resin.

According to the optoelectric composite cable of the present invention, the optical fiber is accommodated in a tube having a Shore D hardness of 65 or more and arranged so as to be in contact with the inner peripheral surface of the tube. It is possible to prevent the application of excessive side pressure and excessive bending and twisting. Further, the tensile strength is improved, and it is possible to prevent application of excessive tension to the optical fiber.
Thus, compared with the case where a reinforcing member such as a strength member is provided, the application of external force to the optical fiber can be suppressed as much as possible without causing an increase in diameter, and good transmission characteristics can be maintained.

It is sectional drawing which shows the example of embodiment of the photoelectric composite cable which concerns on this invention.

Hereinafter, an example of an embodiment of a photoelectric composite cable according to the present invention will be described with reference to the drawings.
As shown in FIG. 1, the optical / electrical composite cable 11 includes an optical fiber core wire (optical fiber) 12 and a plurality of electric wires 15 inside a jacket 20 that is an outermost layer. A plurality of optical fiber cores 12 are provided and accommodated in a protective tube (tube) 13 disposed at the center of the cross section of the optical / electrical composite cable 11.

  An inner side of the outer jacket 20 and an outer side of the protective tube 13 serves as a housing portion 14. In the housing portion 14, for example, a plurality of electric wires 15 and a plurality of interpositions 16 are arranged. The electric wire 15 is, for example, a twisted pair cable, a coaxial cable, or an insulated cable, and is, for example, a cable of about AWG 20 to 46 according to the AWG (American Wire Gauge) standard. In this example, two of the four electric wires 15 are signal lines, and two are power lines. In addition, a presser winding 18, a shield layer 19, and a jacket 20 are sequentially provided around the housing portion 14. The thickness of the accommodating portion 14 (the distance between the outer periphery of the protective tube 13 and the inner periphery of the presser winding 18) is preferably equal to or slightly larger than the outer diameter of the electric wire 15 and the interposition 16.

  The optical fiber core 12 accommodated in the protective tube 13 is obtained by forming a coating layer made of an ultraviolet curable resin around a glass fiber having a diameter of 0.125 mm made of a core and a cladding, and the outer diameter of the coating layer. Is 0.25 mm. Furthermore, a coating layer may be further provided to form an optical fiber core wire 12 having an outer diameter of 0.9 mm, or an optical fiber cord in which the optical fiber core wire 12 is further covered with a tensile fiber and a coating layer.

  The optical fiber core 12 includes a hard plastic clad fiber (H-PCF) that is made of glass and a clad is made of high-hardness plastic and is strong against bending (kinks) and hardly broken, and the core and clad are made of plastic. It may be a plastic fiber.

  For example, when the photoelectric composite cable 11 is used without being bent to a very small diameter like a CCD cord which is a medical sensor cord, a glass fiber can be used, such as a USB (Universal Serial Bus) cable or HDMI. In the case of being bent to a small diameter such as a (High-Definition Multimedia Interface) cable, it is preferable to use a hard plastic clad fiber.

  An optical fiber core wire 12 is accommodated inside the protective tube 13 so as to be in contact with the inner peripheral surface of the protective tube 13. The optical fiber cores 12 have two to four, and the optical fiber cores 12 are in contact with each other, and all the optical fiber cores 12 are inscribed in the protective tube 13, whereby the cross section of the protective tube 13 as shown in FIG. , The position of each optical fiber core wire 12 is fixed in the radial direction. If the optical fiber core wire 12 is twisted loosely (with a long pitch), the position is also fixed in the circumferential direction of the protective tube 13 as seen in the cross section shown in FIG. The protective tube 13 needs to have a certain degree of hardness in order to protect the optical fiber core wire 12 from external force without using another reinforcing member. For this reason, the protective tube 13 has a Shore D hardness of 65 or more, and can reliably protect the optical fiber core 12 accommodated therein. Moreover, the protective tube 13 needs to have a function as a buffer material that absorbs a lateral pressure from the electric wire 15 or the like. For this reason, the protective tube 13 has a thickness of 0.05 mm or more and has a function of satisfactorily absorbing the side pressure from the electric wires 15 and the like. In this example, the thickness of the protective tube 13 is about 0.25 mm. Moreover, the outer diameter of the protective tube 13 is 1.0 mm, for example. Since the outer diameter of the cable increases as the protective tube 13 becomes thicker, a thickness up to about 0.8 mm is practical.

As a material for such a protective tube 13, it is preferable to use a tetrafluoroethylene-ethylene copolymer (ETFE) resin which is a resin material having excellent mechanical strength.
The protective tube 13 is formed so as to cover the optical fiber core wire 12 by extrusion coating a resin around the optical fiber core wires 12 arranged.

  The electric wire 15 as the signal line has a conductor with an outer diameter of 0.30 mm formed by twisting seven strands with an outer diameter of 0.1 mm made of, for example, tin-plated annealed copper wire or copper alloy wire. . Then, the conductor 15 is covered with an insulating sheath having a thickness of 0.14 mm, thereby forming the electric wire 15 having an outer diameter of 0.58 mm. Moreover, the electric wire 15 as a power line has a conductor with an outer diameter of 0.38 mm formed by twisting seven strands with an outer diameter of 0.127 mm made of, for example, a tinned annealed copper wire or a copper alloy wire. Yes. Then, by covering this conductor with an insulation having a thickness of 0.1 mm, the electric wire 15 has an outer diameter of 0.58 mm. There are two signal lines and two power lines. As a material for the outer sheath of the electric wire 15, a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (excellent in heat resistance, chemical resistance, non-adhesiveness, self-lubricating property, etc.) for both signal lines and power lines ( PFA) resin is preferably used.

  As the presser winding 18, a resin tape formed from a polyethylene terephthalate (PET) resin having excellent heat resistance and wear resistance is used. The inner diameter of the portion around which the presser winding 18 is wound is, for example, 2.2 mm. As the presser winding 18, a paper tape or a resin tape made of polytetrafluoroethylene (PTFE) resin may be used.

  The shield layer 19 is formed by braiding a tin-plated copper alloy wire having an outer diameter of several tens of μm (for example, an outer diameter of about 0.03 mm or 0.04 mm), and is formed to a thickness of about 0.1 mm. . As the shield layer 19, a copper alloy wire may be wound horizontally, or a metal resin tape in which a copper foil or an aluminum foil is formed on a resin tape formed from a polyethylene terephthalate (PET) resin may be wound. good.

  The jacket 20 is made of polyvinyl chloride (PVC), polyolefin resin, or the like. Non-halogen polyolefin-based resins include mixtures of elastomers such as ethylene-vinyl acetate copolymer (EVA), polyethylene (PE), and styrene ethylene butylene styrene block copolymer (SEBS). Moreover, what added a weathering agent, antioxidant, and anti-aging agent to polyethylene (PE) may be used. In addition, as the jacket 20 using this polyethylene (PE), a non-flame retardant material that does not contain a flame retardant may be used. The jacket 20 has a thickness of 0.1 to 0.5 mm, an outer diameter of 2 to 10 mm, for example, a thickness of about 0.25 mm, and an outer diameter of 3.0 mm.

According to the photoelectric composite cable 11 configured as described above, the optical fiber core wire 12 is accommodated in the protective tube 13 having a Shore D hardness of 65 or more, and is disposed so as to be in contact with the inner peripheral surface of the protective tube 13. Therefore, it is possible to prevent application of excessive lateral pressure from the electric wire 15 or the like to the optical fiber core wire 12 and generation of excessive bending or twisting. Further, the tensile strength is improved, and it is possible to prevent application of excessive tension to the optical fiber core wire 12.
Thus, compared with the case where a reinforcing member such as a strength member is provided in the protective tube 13, it is possible to suppress external force from being applied to the optical fiber core wire 12 as much as possible without causing an increase in diameter and to achieve good transmission. Characteristics can be maintained.

In the above-described embodiment, the two optical fiber core wires 12 are accommodated in the protective tube 13, but the number of the optical fiber core wires 12 is not limited to two. Although the position of the optical fiber core wire 12 may be arranged at a position slightly deviated from the center of the cross section of the optoelectric composite cable 11, the optical fiber core wire 12 is arranged at the center of the cross section of the optoelectric composite cable 11. preferable.
Further, the number, thickness, and type of the electric wires 15 and the interpositions 16 are not limited to the above embodiment. In the above example, since there are two signal lines and two power lines, the cable jacket 14 is arranged in a circular shape with the interposition 16 disposed between them. Depending on the number of the electric wires 15, even if only the electric wires 15 are arranged without providing the interposition 16 in the accommodating portion 14, the interposition 16 may not be included if the outer cover 20 has a circular cross section. The intervening 16 is a fiber having a tensile strength of less than 2000 MPa, and a fiber such as rayon or nylon can be used.

  Various photoelectric composite cables were prepared, and the transmission loss of the optical fiber core of each photoelectric composite cable was evaluated by the insertion loss method.

(1) Evaluation method A connector is connected to both ends of a photoelectric composite cable having a length L of 2 m, one connector is connected to a power meter, and the other connector is connected to a light transmitting device. Light is transmitted from the light transmitting device, and the output power Po from the optical fiber core wire is measured with a power meter at a measurement wavelength of 850 nm. From the measured output power Po, incident power Pi incident on the optical fiber core, and length L of the optical / electrical composite cable, the transmission loss α of the optical fiber core including the loss at the connector is obtained from the following equation.
α = (Pi−Po) / L

  By the above insertion loss method, the transmission loss α1 of the optical fiber core wire is obtained in a state where the optical / electrical composite cable is straightened, and then the intermediate part of the optical / electrical composite cable is wound 10 times (turns) around a mandrel having a diameter of 4 mm. As a result, the transmission loss α2 including the loss at the connector of the optical fiber core is obtained.

  The difference (α2−α1) between the transmission loss α2 in the state where the optoelectric composite cable is wound and the transmission loss α1 in the state where the optoelectric composite cable is straightened is defined as the increase in transmission loss, and this increase in transmission loss is 1 dB / 10. A case where the number of turns was less than or equal to a turn was evaluated as acceptable (◯), and a case where the number exceeded 1 dB / 10 turns was regarded as unacceptable (x).

(2) Photoelectric composite cable to be evaluated A plurality of optical fiber cores of a hard plastic clad fiber (H-PCF) having an outer diameter of 0.25 mm are accommodated in a protective tube, and between the protective tube and the jacket, In the same manner as in the above embodiment, optical composite cables for USB cables of Examples 1 and 2 and Comparative Example 1 having an outer diameter of 3.0 mm that accommodated electric wires and strength members were prepared. In Examples 1 and 2 and Comparative Example 1, the protective tube and its internal structure were different.

Example 1
A protective tube made of tetrafluoroethylene-ethylene copolymer (ETFE) resin having a Shore D hardness of 70, an inner diameter of 0.54 mm, and a thickness of 0.23 mm is brought into contact with the inner peripheral surface of the three optical fiber core wires. And placed in the circumferential direction.

(Example 2)
A protective tube made of tetrafluoroethylene-ethylene copolymer (ETFE) resin having a Shore D hardness of 65, an inner diameter of 0.50 mm, and a thickness of 0.25 mm is brought into contact with the inner peripheral surface of the two optical fiber core wires. And placed in the circumferential direction.

(Comparative Example 1)
Three optical fiber core wires are arranged in the circumferential direction so as to come into contact with the inner peripheral surface of a protective tube made of polyvinyl chloride (PVC) having a Shore D hardness of 50, an inner diameter of 0.54 mm, and a thickness of 0.23 mm. And housed.

(3) Evaluation results As shown in Table 1, in Examples 1 and 2 using a protective tube having a Shore D hardness of 65 or more, the increase in transmission loss of the optical fiber core is 1 dB / 10 turns or less. And passed (optical fiber core wire loss: ○). On the other hand, in Comparative Example 1 using a protection tube with a Shore D hardness of 50, the increase in the transmission loss of the optical fiber exceeds 1 dB / 10 turns and fails (optical fiber loss: x). became.

  As described above, in Examples 1 and 2, the optical fiber core wire is protected by the protective tube having a Shore D hardness of 65 or more, and excessive lateral pressure is applied to the optical fiber core wire from the electric wire and excessive bending or twisting is performed. It has been found that transmission loss does not increase even in a wound state because the occurrence of this is prevented, and the tensile strength is improved to prevent application of excessive tension to the optical fiber core wire.

  On the other hand, in the comparative example 1, since the Shore D hardness of the protective tube protecting the optical fiber core wire is 50 which is less than 65, application of excessive side pressure from the electric wire or the like to the optical fiber core wire and excessive It has been found that the occurrence of bending and twisting cannot be sufficiently prevented, and the transmission loss increases because excessive tension is applied to the optical fiber.

11: photoelectric composite cable, 12: optical fiber core wire (optical fiber), 13: protective tube (tube), 15: electric wire, 20: jacket

Claims (2)

An optical / electrical composite cable having a plurality of optical fibers and a plurality of electric wires inside the outer jacket,
The optical fiber is housed in a tube having a Shore D hardness of 65 or more and a thickness of 0.05 mm or more and 0.8 mm or less, the optical fibers are in contact with each other, and all the optical fibers are formed of the tube. Arranged so as to contact the inner peripheral surface, the plurality of electric wires are arranged around the tube ,
An optical / electrical composite cable characterized in that, when wound on a mandrel having a diameter of 4 mm, an increase in transmission loss of light at a wavelength of 850 nm propagating through the optical fiber is 1 dB / 10 turns or less . The photoelectric composite cable according to claim 1,
The tube is formed of a tetrafluoroethylene-ethylene copolymer resin.

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