JP4886024B2 - Conversion unit of cable for withdrawal - Google Patents

Description

  The present invention relates to an optical cable from a trunk cable to a relay device (optical node device) or a base station (hereinafter referred to as “relay station”), a so-called drop cable in an optical communication network. The present invention relates to a conversion unit for a cable for dropping to be converted into an optical fiber.

  In an optical communication network such as CATV, a small number of drop cables are used for branching and dropping from several tens to several hundreds of trunk cables to each relay station. In many cases, the cable for withdrawal has a cable structure using a 4-core tape in consideration of the connection work with the main cable, and the repeater side in consideration of the connection work at the relay station. There are many single-core cord structures with connector processing. For this reason, the pull-out cable includes a conversion unit for converting a multi-core optical fiber, for example, a multi-core tape cable into a single-core optical fiber.

  The cable for dropping is often installed in an outdoor environment such as on a pillar or on the roof of a building. Therefore, the conversion part is required to have waterproof performance and high strength from the handling environment. Specifically, when water intrudes into the cable, the water may travel through the cable and reach the conversion unit. In consideration of such a case, the conversion unit needs to have a waterproof performance to prevent water from entering the cable.

  Conventionally, in order to provide waterproof performance to such a conversion unit, a structure of an end portion of an optical fiber cable in which a resin is injected into a casing of the conversion unit to maintain watertightness is known (for example, Patent Documents). 1). A structure in which an elastic resin made of an elastic epoxy resin or the like is filled in the housing is also known (see, for example, Patent Document 2).

  For example, the connection work between the cable for dropping and the repeater is performed in an outdoor environment such as on a pillar or on the roof of a building as described above. However, since the work is normally performed with the conversion part fixed, the effects of twisting, pulling, bending, etc. when laying the cable are applied to the conversion part, or unexpected force is applied depending on the handling of the operator. There is also a possibility that the optical fiber is broken. Therefore, a high-strength structure is necessary in consideration of such a situation.

  Conventionally, as a means for increasing the strength of the conversion unit, as described above, a method of integrating the optical fiber in the conversion unit by filling the conversion unit from the multi-core cable to the single-core optical fiber (for example, Patent Document 1) And a method of inserting a tension member into a gripping bracket and caulking and fixing the gripping bracket, or bending the tip of the tension member to an end of the gripping bracket (for example, for example). , See Patent Document 1).

Japanese Utility Model Publication No. 62-87302 Japanese Patent No. 4094980

  As described above, the conversion portion needs waterproof performance and high strength, and various devices have been devised. However, the conventional technology has a problem with high strength in spite of waterproof performance. That is, it is insufficient to improve the strength simply by filling the conversion portion with resin and integrating the optical fiber of the conversion portion, and it is necessary to process the tension member of the multi-core cable to improve the strength at the conversion portion. is there. The treatment of the tension member in Patent Document 1 presents the solution, but there is a problem that the processing method is complicated, for example, when work is performed in an outdoor environment, workability is poor and takes time. .

  The present invention has been made to solve the above-described problems, and can integrate an optical fiber of a conversion unit that converts the number of cores from a multi-core cable to a single-core optical fiber, and can easily tension a multi-core cable. It is an object of the present invention to provide a conversion unit for a cable for dropping that can process members and increase strength.

  In order to achieve this object, a first aspect of a conversion unit for a drop cable according to the present invention is a conversion unit for a drop cable that converts the number of cores from a multi-core cable to a single-core optical fiber, A single-core optical fiber insertion hole for inserting a multi-core cable insertion hole for inserting a multi-core cable at one end of the housing to be configured and inserting a single-core optical fiber for the number of cores of the multi-core cable at the other end And a tension member insertion hole for inserting a tension member of a multi-core cable, each having an opening at the top of the housing and a screw hole penetrating the bottom of the housing at the bottom of the housing Is provided, and a multi-core cable, a single-core optical fiber, and a tension member are respectively inserted into the insertion holes and arranged in the casing, and resin is molded from the opening of the casing. In addition, the conversion part from the multi-core cable to the single-core optical fiber is integrated in the housing, and the tension member is fixed from the outside of the housing by inserting screws through the screw holes at the bottom of the housing It is characterized by.

  Moreover, the 2nd aspect of the conversion part of the cable for withdrawal of this invention is a 1st aspect. WHEREIN: The cover is covered on the opening part of the housing | casing, It is characterized by the above-mentioned.

  Further, according to a third aspect of the conversion portion of the cable for dropping according to the present invention, in the first aspect or the second aspect, the single-core optical fiber is coated with a single-core cord coating, and the single-core cord coating is coated with a resin. The conversion part of the single-core optical fiber is integrated from the multi-core cable by molding.

  According to a fourth aspect of the conversion portion of the cable for withdrawal according to the present invention, in the first to third aspects, the multi-core cable is fixed by mechanical means in the multi-core cable insertion hole of the housing. And

  Further, according to a fifth aspect of the conversion unit of the dropping cable of the present invention, in the fourth aspect, the multi-core cable and the housing are fixed by mechanical means by attaching screws to a plurality of screw holes provided in the housing. It is characterized in that it is performed by inserting and biting the tip of the screw into the outer sheath of the multi-core cable.

  According to a sixth aspect of the conversion portion of the cable for dropping according to the present invention, in the fourth aspect, the fixing of the multi-core cable and the casing by the mechanical means is performed at a portion inscribed in the outer casing of the multi-core cable. An aluminum laminate tape is wound, and the multi-core cable and the housing are bonded and fixed by an adhesive on the outside of the aluminum laminate tape.

  According to the present invention, since the optical fiber of the conversion part of the cable for dropping is sufficiently integrated and waterproofed, there is no risk of disconnection of the optical fiber even when used in an outdoor environment. It has the remarkable effect that the conversion part of a highly efficient cable for dropping can be realized.

It is a side view which shows one Embodiment of the conversion part of the cable for withdrawal of this invention. It is a top view which shows one Embodiment of the conversion part of the cable for withdrawal of this invention. It is the perspective view which showed the example at the time of providing a cover in the housing | casing of the conversion part of the cable for withdrawal of this invention. It is sectional drawing which showed an example of the multi-core cable used for the conversion part of the cable for withdrawal of this invention. It is a figure which shows an example of the structure of the coating | coated for the single core cord for carrying out single core coding of the single core optical fiber used for the conversion part of the cable for dropping of this invention. It is a figure for demonstrating the means to fix a multi-core cable and a housing | casing used for the conversion part of the cable for withdrawal of this invention. It is a figure which shows the test method for measuring the tension | pulling characteristic of the conversion part of the cable for dropping of this invention. It is a figure which shows the test method for measuring the bending characteristic of the conversion part of the cable for withdrawal of this invention. It is a figure which shows the test method for measuring the twist characteristic of the conversion part of the cable for a withdrawal of this invention.

  Hereinafter, a preferred embodiment of a conversion unit of a cable for dropping according to the present invention will be described with reference to the drawings. In the following figures, in principle, the same parts are denoted by the same reference numerals.

  FIG. 1 is a side view showing an embodiment of a conversion part of a cable for dropping according to the present invention. FIG. 2 is a plan view showing an embodiment of the conversion part of the cable for withdrawal according to the present invention. 1 and 2, the housing 1 of the optical fiber cable conversion unit of the present invention is made of a metal such as stainless steel (SUS) or brass in consideration of maintaining strength and being used in an outdoor environment. It is formed by.

  One end of the housing 1 is provided with a multi-core cable insertion hole 2 for inserting a multi-core cable, for example, a cable made of 4-fiber tape fiber, and the other end is separated from the multi-core cable. A single-fiber optical fiber insertion hole 3 through which the single-fiber optical fiber is inserted is provided. The single-core optical fiber insertion holes 3 are provided as many as the number of cores of the multi-core cable (four in this embodiment).

  The housing 1 is opened at the top, and the conversion operation from the multi-core cable to the single-core optical fiber is performed in the opening 4.

  Specifically, a multi-core cable 5, for example, a 4-core tape cable, is inserted through the multi-core cable insertion hole 2, and a single-core separation operation from the multi-core cable 5 to the optical fiber 6 is performed at the opening 4 of the conversion section. Each optical fiber 6 separated by a single core is inserted into the single optical fiber insertion hole 3 of the housing 1 and drawn out of the housing. The single-core optical fiber 6 is coated with a single-core cord coating 7 for making the single-core optical fiber 6 into a single-core code. Although not shown, a connector is attached to the end of the single-core optical fiber 6 opposite to the multi-core cable side. Further, the multi-core cable 5 has a metal tension member 8 disposed in the center thereof, and a plastic resin spacer 10 for disposing the tape core wire 9 around the tension member 8.

  A step 11 is provided inside the housing 1, and the multi-core cable is prevented from entering beyond a certain level at the step 11 so that the multi-core cable 5 can be inserted by a predetermined length. When forming the conversion portion, the outer sheath of the multi-core cable 5 is peeled off, the tip of the spacer 10 is removed, the four-core tape and the tension member 8 are taken out, and the four-core tape is used as the single-core optical fiber 6. The single optical fibers 6 are inserted into the single optical fiber insertion holes 3. Then, the tension member 8 is inserted through the tension member insertion hole 12.

  Further, a screw hole 13 is provided at the bottom of the housing 1 so as to penetrate the housing 1 to the tension member insertion hole 12 in a direction orthogonal to the tension member insertion hole. A screw 14 for fixing the tension member 8 is inserted from the screw hole 13. The number of screw holes is not particularly limited, but at least two screw holes are necessary to ensure the fixation of the tension member 8. The screw 14 is preferably a screw of M3 or more. And in order to fix the tension member 8 reliably, it is preferable to fix with the fastening torque of 60 MPa or more.

  Thus, after the conversion process from the multi-core cable 5 to the single-core optical fiber 6 is completed in the housing 1, the resin 15 is molded from the opening 4 at the top of the housing 1. By molding the resin 15 in the housing 1, it is possible to secure waterproof performance and to integrate the conversion part from the multi-core cable 5 to the single-core optical fiber 6, and to increase the strength of the conversion part. Is possible.

  The single-core optical fiber 6 is coated with a single-core cord coating 7, and the tip of the single-core cord coating 7 is also disposed in the housing 1, and the single-core cord coating 7 is also a tip. In addition, the resin 15 is molded and integrated. Therefore, there is no possibility that the coated single-core cord coating 7 is detached from the single-core optical fiber 6.

  The type of the resin 15 used here is not particularly limited as long as it is suitable for the purpose of the present invention, and examples thereof include epoxy resin, EVA resin, urethane resin, and the like, as long as they have waterproof performance and mechanical strength. Any kind of resin can be used.

  By the way, when the resin 15 is molded from the opening 4 to form the conversion portion from the multi-core cable 5 to the single-core optical fiber 6, the resin 15 is molded, so that waterproof performance is ensured, so that There is no problem in actually using it. However, it is preferable to provide a lid on the opening 4 in order to ensure higher waterproof performance and mechanical strength. FIG. 3 is a perspective view showing an example in which a cover is provided on the housing 1. In FIG. 3, a lid 16 made of the same material as the housing 1 is placed over the opening 4 of the housing 1 and fixed with an adhesive. By doing so, higher waterproof performance and mechanical strength are ensured. In FIG. 3, the illustration of the mold resin 15 is omitted for convenience of explanation.

  Here, the multi-core cable 5 has a structure as shown in FIG. FIG. 4 is a cross-sectional view showing an example of the multi-core cable 5. In FIG. 4, the multi-core cable 5 has a tension member 8 in the center, and a plurality of grooves 41 (for example, 3 in the case of this figure) made of a plastic resin provided so as to cover the tension member 8. A plurality of four-core tape type fibers 9 are laminated in the groove). The spacer 10 is covered with a jacket 42 made of polyethylene, and a tear string 43 is provided at a part of the jacket 42.

  The outer jacket 42 is torn by the tear string 43 to expose the spacer 10, and the spacer 10 is cut leaving the tension member 8, thereby separating the four-core tape fiber 9 into a single core. Then, the multi-core cable 5 is inserted into the multi-fiber cable insertion hole 2 of the housing 1, the tension member 8 is inserted into the tension member insertion hole 12, and the four-fiber tape type fiber 9 is separated into single fibers. The fiber 6 is inserted into the single-core optical fiber insertion hole 3.

  The tension member 8 is fixed by inserting the screw 14 into the screw hole 13 from the outside of the housing 1 as described above. Further, when the single-core optical fiber 6 is inserted into the single-core optical fiber insertion hole 3, the single-core optical fiber 6 is coated with a single-core cord coating 7, and is drawn out of the housing 1 after being single-core coded. ing.

  FIG. 5 shows the structure of a single-core cord coating 7 for single-fiber coding the single-core optical fiber 6. As shown in FIG. 5A, the cross-section of the single-core cord covering 7 includes a reinforcing fiber 52 disposed around a plastic pipe 51, and a resin jacket 53 provided around the reinforcing fiber 52. For example, nylon (registered trademark) is used for the plastic pipe 51. Further, Kevlar (registered trademark) is used as the reinforcing fiber, and PVC (polyvinyl chloride) is used as the resin jacket 53.

  FIG. 5B shows a side view of the single-core cord coating 7. In FIG. 5B, the plastic pipe 51 protrudes from the reinforcing fiber 52 by, for example, about 2 mm, and the reinforcing fiber 52 protrudes from the resin jacket 53 by about 3 mm. The single-core optical fiber 6 is inserted into the plastic pipe 51 to be encoded as a single-core cable. If the plastic pipe 51 and the reinforcing fiber 52 are protruded little by little in this way, the single-core optical fiber 6 can be easily inserted into the plastic pipe 51 and integrated more firmly with the resin mold. effective.

  On the other hand, the multi-core cable 5 is fixed to the housing 1 by some mechanical means. FIG. 6 shows an example. 6A, the housing 1 is provided with a plurality of screw holes 61 (three in this figure), and screws (not shown) are inserted through the screw holes 61 so as to bite into the jacket 42 of the multi-core cable 5. Thus, the multi-core cable 5 and the housing 1 are fixed. 6B, an aluminum laminate tape 62 is wound around a portion inscribed in the outer casing 1 of the multi-core cable 5, and the multi-core cable 5 and the casing 1 are bonded to the outer side of the aluminum laminate tape with an adhesive 63. This shows an example in which a so-called LAP process is performed. In FIG. 6B, the right part of the drawing is omitted. As described above, by mechanically fixing the multi-core cable 5 and the housing 1, it is possible to obtain a conversion unit for a withdrawal cable with higher strength.

  As described above, the conversion part of the cable for dropping according to the present invention is designed to improve the waterproof performance by molding resin at the conversion part between the multi-core cable and the single-core optical fiber, and to attach the tension member of the multi-core cable. Since it fixes with a screw from the outside of a housing | casing, the conversion part which has high intensity | strength compared with the past can be provided. The transmission characteristics and mechanical strength characteristics of the conversion portion of the cable for dropping according to the present invention were measured, and the effects were confirmed.

A tensile property test, a bending property test, and a twisting property test were performed on the conversion portion of the cable for dropping according to the present invention as follows. The test method for each test is shown in FIGS.
<Tensile property test>
FIG. 7 is a diagram showing a test method for measuring the tensile characteristics of the conversion portion of the cable for dropping according to the present invention. The conversion unit 71 of the cable for dropping according to the present invention is fixed to a tensile tester (Strograph R) with a clamp 72, and a portion 1 m from the conversion unit 71 is fixed with another clamp 73, and the tensile tension is 10 mm in the direction of the arrow. The load was applied at a pull rate of / min. The optical fibers 74a and 74b at the end of the multi-core cable 5 are fused and connected (x mark) to form a closed loop, and 1310 nm light is incident on the optical fiber 75a drawn from the conversion unit 71 by the LED light source 76. The transmission loss (residual loss) of the light emitted from the optical fiber 75 b drawn out from the conversion unit 71 was measured with the power meter 77. The LED light source 76 and the optical fiber 75a, and the power meter 77 and the optical fiber 75b are connected by connectors 78a and 78b, respectively. The tensile tension was applied up to 1275 MPa by such a test method.
<Bending characteristic test>
FIG. 8 is a diagram showing a test method for measuring the bending characteristics of the conversion portion of the cable for dropping according to the present invention. The conversion part 82 of the cable for dropping of the present invention was sandwiched and fixed to a mandrel 81 having a bending radius (R) of 100 mm. Then, the multi-core cable 5 was bent 10 times along the mandrel 81 with ± 180 ° as one time as indicated by an arrow. The optical fibers 83a and 83b at the end of the multi-core cable 5 are fused and connected (×) to form a closed loop, and 1310 nm light is incident on the optical fiber 84a drawn from the conversion unit 82 by the LED light source 85. The transmission loss (residual loss) of the light emitted from the optical fiber 84 b drawn out from the conversion unit 82 was measured with the power meter 86. The LED light source 85 and the optical fiber 84a, and the power meter 86 and the optical fiber 84b are connected by connectors 87a and 87b, respectively.
<Torsion characteristic test>
FIG. 9 is a diagram showing a test method for measuring the twisting characteristics of the conversion portion of the cable for dropping according to the present invention. The conversion portion 91 of the cable for dropping according to the present invention is fixed with a vise 92, and the portion 1 m from the conversion portion 91 of the multi-core cable 5 is fixed with another vise 93 to the multi-core cable 5 at 3600 ° (cable 10 turns) was applied. The optical fibers 94a and 94b at the end of the multi-core cable 5 are fused and connected (x) to form a closed loop, and 1310 nm light is incident on the optical fiber 95a drawn from the conversion unit 91 by the LED light source 96. The transmission loss (residual loss) of the light emitted from the optical fiber 95 b drawn out from the conversion unit 91 was measured with the power meter 97. The LED light source 96 and the optical fiber 95a, and the power meter 97 and the optical fiber 95b are connected by connectors 98a and 98b, respectively.

  About the above test results, it shows in Table 1 compared with a comparative example. The conversion part of the comparative example is a conventional example having only a structure in which resin is injected into the housing of the conversion part to maintain watertightness.

  From the results of Table 1, in the tensile property test, the conversion part of the comparative example showed an increase in transmission loss and disconnection with a tensile force of 590 MPa, whereas the conversion part of the present invention applied a tensile tension of 1275 MPa. Even though there was no disconnection, no change in transmission loss was observed. Further, in the bending characteristic test, the conversion part of the comparative example showed an increase in transmission loss, whereas the conversion part of the present invention did not show disconnection or change in transmission loss even when bending was applied. Further, for the twisting characteristic test, the conversion part of the comparative example showed an increase in transmission loss and disconnection at 540 ° (cable 1.5 rotation), whereas the conversion part of the present invention was 3600 ° (cable) Even when a load of 10 revolutions) was applied, no disconnection or transmission loss change was observed.

  As described above, according to the present invention, the conversion points of the multi-core cable and the single-core optical fiber are integrated by molding the resin in the casing, and the tension member of the multi-core cable is fixed from the outside of the casing with a plurality of screws. An extremely high-strength cable for cable conversion can be realized.

  The conversion unit of the withdrawal cable of the present invention can be applied as a node cable of a CATV optical communication network and a withdrawal cable of a PHS optical communication network.

DESCRIPTION OF SYMBOLS 1 Housing | casing 2 Multi-fiber cable insertion hole 3 Single-core optical fiber insertion hole 4 Opening part 5 Multi-core cable 6 Single-core optical fiber 7 Single-core cord coating | cover 8 Tension member 9 Tape core wire 10 Spacer 11 Step 12 Tension member insertion hole 13 Screw hole 14 Screw 15 Mold resin 16 Lid

Claims (6)

  A conversion unit for a pull-down cable that converts the number of cores from a multi-core cable to a single-core optical fiber, and has a multi-core cable insertion hole for inserting the multi-core cable at one end of the casing constituting the conversion unit. A single-core optical fiber insertion hole for inserting a single-core optical fiber corresponding to the number of cores of the multi-core cable and a tension member insertion hole for inserting a tension member of the multi-core cable. An opening is provided in the upper part of the casing, and at least one screw hole penetrating the bottom of the casing is provided in the bottom of the casing, the multi-core cable, the single core The optical fiber and the tension member are respectively inserted into the insertion holes and arranged in the casing, and resin is molded from the opening of the casing to thereby form the inside of the casing. The conversion point from the core cable to the single-core optical fiber is integrated, and further, the tension member is fixed from the outside of the casing by inserting a screw from the screw hole at the bottom of the casing. The conversion part of the characteristic cable for withdrawal.   2. The conversion unit for a cable for dropping according to claim 1, wherein a cover is put on the opening of the housing.   The single-core optical fiber is coated with a single-core cord coating, and the single-core optical fiber conversion part is integrated with the single-core cord coating from the multi-core cable by resin molding. The conversion part of the cable for withdrawal of Claim 1 or Claim 2.   The conversion of the dropping cable according to any one of claims 1 to 3, wherein the multi-core cable is fixed by mechanical means in a multi-core cable insertion hole of the housing. Department.   The multi-core cable and the housing are fixed by mechanical means by inserting screws into a plurality of screw holes provided in the housing, so that the tip ends of the screws bite into the outer sheath of the multi-core cable. 5. The conversion unit for a withdrawal cable according to claim 4, wherein   The multi-core cable and the housing are fixed by mechanical means. An aluminum laminate tape is wound around a portion of the multi-core cable that is inscribed in the housing, and the adhesive is provided on the outside of the aluminum laminate tape. 5. The conversion unit for a withdrawal cable according to claim 4, wherein the multi-core cable and the housing are bonded and fixed.

Images