JP2012043557A - Optical-electrical composite cable - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical-electrical composite cable capable of being smoothly arranged in a narrow space or the like, while maintaining an excellent transmission characteristic of an optical fiber by preventing external force from being applied to the optical fiber without increasing in diameter of the cable.SOLUTION: An optical-electrical composite cable 11 includes optical fiber core wires 12, and a plurality of electric wires 15 inside an outer sheath 20, in which: the plurality of electric wires 15 are arranged around the periphery of the optical fiber core wires 12; and the optical fiber core wires 12 are stored in a protective tube 13; and the protective tube 13 is composed of a resin having elasticity modulus of 300 MPa or more, and has a thickness of 0.1 mm or more; and the plurality of electric wires 15 include single electric wires 15a and a set of two pair electric wires 15b diagonally arranged for each other; and the pair electric wires 15b are arranged in parallel on an outer peripheral surface of the protection tube 13 in a longitudinal direction thereof; and interposing parts 16 are provided between the single electric wires 15a and the pair electric wires 15b on an outer peripheral surface side of the protective tube 13.

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).
In addition, a plurality of optical fibers are arranged at intervals on the outer periphery of the core material, and a partition sheet that covers the core material and the optical fiber is provided on the outer side, and a position corresponding to the interval between the optical fibers on the outer side of the partition sheet. There is also known an electric wire disposed on the outside of which a jacket is provided outside (see, for example, Patent Document 2).

Japanese Utility Model Publication No. 62-135309 Japanese Utility Model Publication No. 60-109216

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 particular, when the electric wire arranged on the outer periphery is a stranded wire, the outer periphery of the stranded wire has a shape having unevenness along the longitudinal direction, so that the optical fiber is locally bent when the cable is bent. The side pressure will increase.
In this case, it is possible to suppress excessive bending and twisting by stiffening the sheath that accommodates the optical fiber or providing a reinforcing member such as a strength member in the sheath, but the flexibility of the cable is reduced. As a result, the workability of the wiring deteriorates and the cable diameter increases. Therefore, it is difficult to reduce the diameter of the cable and smoothly route it to a narrow space.

  An object of the present invention is to provide a light that can be smoothly routed to a narrow space or the like while suppressing the external force from being applied to the optical fiber without increasing the diameter of the cable and maintaining good transmission characteristics of the optical fiber. It is to provide an electrical composite cable.

The photoelectric composite cable of the present invention capable of solving the above problems is a photoelectric composite cable having an optical fiber and a plurality of electric wires inside a jacket,
The plurality of electric wires are arranged around the optical fiber;
The optical fiber is housed inside the tube;
The tube is formed of a resin having an elastic modulus of 300 MPa or more and has a thickness of 0.1 mm or more.
The plurality of electric wires are composed of a single electric wire and a set of two electric wires arranged diagonally to each other, and the electric wires are vertically attached in parallel to the outer peripheral surface of the tube,
An interposition is provided between the single electric wire and the counter electric wire on the outer peripheral side of the tube.

  In the photoelectric composite cable of the present invention, it is preferable that a plurality of the single electric wires are vertically attached in parallel to the outer peripheral surface of the tube.

According to the photoelectric composite cable of the present invention, the optical fiber is accommodated inside the tube having a thickness of 0.1 mm or more formed from a resin having an elastic modulus of 300 MPa or more, and is twisted on the outer peripheral side of the tube. Since a single electric wire and a pair of paired electric wires are arranged, excessive lateral pressure from the electric wire is applied to the optical fiber without reducing the flexibility of the cable or increasing the diameter of the cable. Further, excessive bending and twisting can be prevented.
Moreover, since the counter wire is vertically attached to the outer peripheral surface of the tube, the diameter of the cable can be reduced as compared with the case where the counter wire is twisted and arranged. That is, the cable of the present invention can be smoothly wired in a narrow space or the like while maintaining the good transmission characteristics of the optical fiber while making the cable of the present invention small.
In addition, by arranging the single electric wire and the counter electric wire at diagonal positions and providing an intervening between these single electric wire and the counter electric wire, the balance of the internal mass is kept good and the cable is not twisted.

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

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 is a housing portion 14, and a plurality of electric wires 15 are arranged in the housing portion 14. As the electric wires 15, there are a plurality of single electric wires 15a used as power lines and a pair of electric wires 15b used as a signal line for differential transmission, for example. The single electric wire 15a and the counter electric wire 15b are disposed at positions opposite to the center of the optoelectric composite cable 11 that is diagonal to each other. The electric wire 15b is vertically attached in parallel to the outer peripheral surface of the protective tube 13 without being twisted. Each individual electric wire 15 a is also vertically attached to the outer peripheral surface of the protective tube 13 in parallel.

  Each of the single electric wire 15a and the counter electric wire 15b is an insulated cable in which a conductor obtained by twisting a plurality of strands made of annealed copper wire or copper alloy wire plated with tin is covered with a jacket, for example, AWG (American Wire Gauge) standard AWG 20-46 cable. Fluorine resin such as tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA) resin excellent in heat resistance, chemical resistance, non-adhesiveness, self-lubricating property, etc. is used as the material of the jacket of the insulated cable Is preferred. In addition, as the jacket of the insulated cable, polyethylene (PE) resin or polyvinyl chloride (PVC) resin may be used.

A plurality of interpositions 16 are accommodated in the accommodating portion 14 on the outer peripheral side of the protective tube 13 between the single electric wire 15a and the electric wire 15b. As these interpositions 16, it is preferable to use, for example, a string of fibers such as rayon or nylon.
As described above, the presser winding 18, the shield layer 19, and the jacket 20 are sequentially provided around the housing portion 14 in which the electric wire 15 and the interposition 16 are housed.

  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 an optical fiber made of a core and a cladding, and the core diameter is 0.05 to 1.0 mm. (For example, 0.08 mm), the outer diameter of the cladding is 0.125 mm, 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.

  Two optical fiber core wires 12 are accommodated inside the protective tube 13. Although only the optical fiber core wire 12 may be accommodated inside the protective tube 13, the strength may be increased by accommodating tensile strength wires and intervening together with the optical fiber core wire 12. There may be a case where three or more optical fiber core wires 12 are accommodated inside the protective tube 13, and a case where one optical fiber core wire 12 is accommodated. When a plurality of optical fiber cores 12 are accommodated in the protective tube 13, it is preferable that the optical fiber cores 12 are vertically attached without being twisted.

The protective tube 13 needs to have a function as a buffer material that absorbs the lateral pressure from the electric wire 15 and the like while protecting the optical fiber core wire 12 from external force. For this reason, the protective tube 13 is formed of a resin having an elastic modulus of 300 MPa or more and has a thickness of 0.1 mm or more. In this example, the protective tube 13 has an inner diameter of about 0.55 mm, an outer diameter of about 1.05 mm, and a thickness of about 0.25 mm.
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, and a polybutylene terephthalate (PBT) resin is used. Also good.
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.

  As the presser winding 18, a resin tape formed from a polyethylene terephthalate (PET) resin having excellent heat resistance and wear resistance is used. 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 wire or 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 has a thickness of about 0.1 mm. Has been. As the shield layer 19, a copper wire or a copper alloy wire may be wound horizontally, and 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. It can be rolled up.

  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 (for example, about 0.25 mm), and an outer diameter of several mm to several tens of mm (for example, 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 formed of a resin having an elastic modulus of 300 MPa or more and having a thickness of 0.1 mm or more. Therefore, the side pressure to the optical fiber core wire 12 can be protected by the protective tube 13 and can be kept small. Further, since the single electric wire 15a and the pair of two electric wires 15b are arranged in parallel without being twisted on the outer peripheral side of the protective tube 13, the flexibility of the photoelectric composite cable 11 is reduced, or the photoelectric composite cable is used. 11 without increasing the diameter of the wire 11, preventing excessive lateral pressure from being applied to the optical fiber core 12 from the single electric wire 15 a and the counter wire 15 b, and preventing occurrence of excessive bending or twisting of the optical fiber core 12. can do.

Moreover, since the counter wire 15b is vertically attached in parallel with the outer peripheral surface of the protective tube 13, the diameter can be reduced as compared with the case where the counter wire 15b is twisted and arranged. That is, without increasing the diameter of the optical / electrical composite cable 11, it is possible to suppress external force from being applied to the optical fiber core 12, and to smoothly route it to a narrow space or the like while maintaining good transmission characteristics of the optical fiber core 12. can do.
In addition, when the counter wires 15b are vertically attached without being twisted as in the photoelectric composite cable 11 of the present embodiment, the electric signals are easily affected by each other as noise. However, the shield layer 19 surrounds the housing portion 14. Since it covers, the influence by the mutual electric signal can be suppressed.

  In addition, since the single electric wire 15a and the counter electric wire 15b are arranged at diagonal positions and the interposition 16 is provided between the single electric wire 15a and the counter electric wire 15b, the tensile strength is increased while maintaining a good balance of the internal mass. Further, application of excessive tension to the optical fiber core wire 12 can also be prevented.

  And since the single electric wire 15a and the counter electric wire 15b are arranged with good balance in this way, the single electric wire 15a, the counter electric wire 15b and the interposition 16 are bundled at one place in the circumferential direction at the terminal portion of the photoelectric composite cable 11. At the same time, the workability can be improved by suppressing the twisting of the single electric wire 15a and the counter electric wire 15b as much as possible. Further, when the single electric wire 15a and the counter electric wire 15b are arranged in a well-balanced manner, the protective tube 13 that accommodates the optical fiber core wire 12 and the single electric wire are also used when the outer sheath 20 is extruded to produce the photoelectric composite cable 11. The twist of the collective core consisting of 15a, the electric wire 15b, and the interposition 16 can be minimized, and the productivity can be improved.

  In addition, since not only the pair of adjacent electric wires 15b but also the individual electric wires 15a are adjacent to each other and accommodated in the accommodating portion 14, when connecting the pair of electric wires 15b and the individual electric wires 15a at the terminal of the photoelectric composite cable 11 The workability can be improved.

  In the optical / electrical composite cable 11, it is preferable that the optical fiber core wire 12 has a clearance of 10 μm or more between the inner peripheral surface of the protective tube 13, and between the optical fiber core wire 12 and the protective tube 13. It is preferable that the friction coefficient between them is 0.5 or less. In this way, when the photoelectric composite cable 11 is bent, the optical fiber core wire 12 can be appropriately moved in the longitudinal direction, and an increase in transmission loss can be prevented without locally meandering. . For example, if the material of the coating layer of the optical fiber core wire 12 and the protective tube 13 is a tetrafluoroethylene-ethylene copolymer (ETFE) resin, which is a fluorine resin, the optical fiber core wire 12 and the protective tube 13 The optical fiber core wire 12 can easily move in the longitudinal direction in the protective tube 13, and an increase in transmission loss can be prevented.

  In the above embodiment, the two optical fiber cores 12 are accommodated in the protective tube 13, but as described above, the number of the optical fiber cores 12 is not limited to two. Further, although the optical fiber core wire 12 is arranged at the center of the cross section of the optoelectric composite cable 11, the position of the optical fiber core wire 12 may be arranged at a position deviated from the center of the cross section of the optoelectric composite cable 11. good. Further, the number, thickness, and type of the electric wires 15 and the interpositions 16 are not limited to the above embodiment.

  A cable 11A shown in FIG. 2 is a cross-sectional structure of an optical / electrical composite cable having a structure in which two electric wires 15a and a counter electric wire 15b of the accommodating portion 14 are twisted together. In this cable 11A, since the two electric wires 15a and the pair of electric wires 15b are respectively twisted, the two electric wires 15a and the pair of electric wires 15b are arranged in a line with respect to the protective tube 13 in which the optical fiber core wire 12 is accommodated. May occur. Note that either the two electric wires 15 a or the counter electric wires 15 b may be arranged in a row with respect to the protective tube 13.

  Therefore, in this cable, since the two single electric wires 15a and the pair of electric wires 15b are respectively twisted with respect to the protective tube 13, the electric wires easily receive a large lateral pressure, and the protective tube 13 also receives a side pressure from the single electric wire 15a or the pair of electric wires 15b. It is easy to receive. Since only one electric wire is in contact with the tube, the pressure applied to the tube increases. That is, with this cable, the transmission loss in the optical fiber core wire 12 increases. Moreover, if both or one of the two single electric wires 15a and the counter electric wire 15b are twisted, the outer diameter of the cable increases correspondingly, and wiring to a narrow space or the like becomes difficult. . In particular, the outer diameter of a cable will become large in the location where both or one of the two single electric wires 15a and the electric wire 15b with respect to the protective tube 13 are arranged in a line.

  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 including the loss at the connector 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 converted into a mandrel having a diameter of 4 mm The transmission loss α2 including the loss at the connector of the optical fiber core wire is obtained as the state of being wound 10 times (turns).

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

(2) Photoelectric composite cable to be evaluated (Example 1)
As Example 1, as in the above embodiment, an optical fiber core wire of a hard plastic clad fiber (H-PCF) having a core diameter of 0.08 mm, a clad diameter of 0.125 mm, and an outer diameter of 0.25 mm is provided inside the protective tube. 2 optical cables for USB cables with an outer diameter of 3.0 mm that contain two single wires and a pair of paired wires vertically between the protective tube and the jacket. Was made. A protective tube made of ethylene-tetrafluoroethylene copolymer (ETFE) resin having an elastic modulus of 300 MPa and a thickness of 0.20 mm was used. Nylon is interposed between the single wire and the counter wire so that each wire does not shift in the circumferential direction when viewed from the cable cross section.

(Comparative Example 1)
As Comparative Example 1, two optical fiber cores of a hard plastic clad fiber (H-PCF) having a core diameter of 0.08 mm, a clad diameter of 0.125 mm, and an outer diameter of 0.25 mm are accommodated inside the protective tube for protection. An optical composite cable for a USB cable having an outer diameter of 4.0 mm, in which two single electric wires and a pair of paired electric wires were accommodated between the tube and the jacket, was produced. In the comparative example 1, like the cable shown in FIG. 2, two single electric wires and a pair of electric wires were twisted together and accommodated. Therefore, in the cable of the comparative example 1, two single electric wires and counter wires may be arranged in a line with respect to the protective tube containing the optical fiber core wire. In addition, either two single electric wires or counter wires may be arranged in a line with respect to the protective tube. A protective tube made of polybutylene terephthalate (PBT) resin having an elastic modulus of 300 MPa and a thickness of 0.20 mm was used.

(Comparative Example 2)
As Comparative Example 2, two optical fiber cores of hard plastic clad fiber (H-PCF) having a core diameter of 0.08 mm, a clad diameter of 0.125 mm, and an outer diameter of 0.25 mm are accommodated inside the protective tube for protection. An optical composite for a USB cable with an outer diameter of 3.0 mm, in which two single wires and a pair of two pairs of wires are housed vertically between the tube and the jacket as in the first embodiment. A cable was produced. As the protective tube, a tube made of polyvinyl chloride (PVC) resin having an elastic modulus of 100 MPa and a thickness of 0.20 mm was used.

(Comparative Example 3)
As Comparative Example 3, two optical fiber cores of a hard plastic clad fiber (H-PCF) having a core diameter of 0.08 mm, a clad diameter of 0.125 mm, and an outer diameter of 0.25 mm are accommodated inside the protective tube for protection. An optical composite for a USB cable with an outer diameter of 3.0 mm, in which two single wires and a pair of two pairs of wires are housed vertically between the tube and the jacket as in the first embodiment. A cable was produced. A protective tube made of polybutylene terephthalate (PBT) resin having an elastic modulus of 300 MPa and a thickness of 0.05 mm was used.

(3) Evaluation Results As shown in Table 1, in Example 1, the transmission loss increase amount of the optical fiber core wire was 1 dBm / 10 turns or less, which was acceptable (optical fiber core wire loss: ◯). On the other hand, in Comparative Examples 1 to 3, the transmission loss increase amount of the optical fiber core wire exceeded 1 dBm / 10 turns and failed (optical fiber core wire loss: x).

  Thus, in Example 1, an optical fiber core wire is accommodated inside a protective tube having an elastic modulus of 300 MPa and a thickness of 0.20 mm, and a single electric wire and 2 on the outer peripheral side of the protective tube. Because this set of paired electric wires is attached vertically, the optical fiber core wire is reliably protected, the tensile strength is improved by the intervention, and the application of excessive tension to the optical fiber core wire is also prevented, It was found that the transmission loss did not increase even when it was wound.

  In contrast, in Comparative Example 1, the optical fiber core wire has an elastic modulus of 300 MPa and is accommodated inside a protective tube formed to a thickness of 0.20 mm. Is twisted, so that a large lateral pressure is applied from the electric wire to the optical fiber core, and excessive bending and twisting cannot be sufficiently prevented, and there is no intervening, so excessive tension is applied to the optical fiber core. It was found that transmission loss increased.

  In Comparative Example 2, the internal structure is the same as in Example 1, but the elastic modulus of the protective tube that accommodates the optical fiber core is 100 MPa, which is less than 300 MPa. It was found that the application of lateral pressure and the occurrence of excessive bending and twisting could not be sufficiently prevented, resulting in an increase in transmission loss.

  In Comparative Example 3, the internal structure is the same as that of Example 1, but the thickness of the protective tube that accommodates the optical fiber core wire is 0.05 mm, which is less than 0.1 mm. It has been found that the application of excessive side pressure and excessive bending and twisting cannot be sufficiently prevented, resulting in an increase in transmission loss.

11: opto-electric composite cable, 12: optical fiber core wire (optical fiber), 13: protective tube (tube), 15: electric wire, 15a: single electric wire, 15b: to electric wire, 16: interposition, 20: jacket

Claims (2)

An optical / electrical composite cable having an optical fiber and a plurality of electric wires inside the outer jacket
The plurality of electric wires are arranged around the optical fiber;
The optical fiber is housed inside the tube;
The tube is formed of a resin having an elastic modulus of 300 MPa or more and has a thickness of 0.1 mm or more.
The plurality of electric wires are composed of a single electric wire and a set of two electric wires arranged diagonally to each other, and the electric wires are vertically attached in parallel to the outer peripheral surface of the tube,
An optical / electrical composite cable, wherein an intervening is provided between the single electric wire and the counter electric wire on the outer peripheral side of the tube. The photoelectric composite cable according to claim 1,
A plurality of the single electric wires are vertically attached in parallel to the outer peripheral surface of the tube.

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