Optical fiber cable covered with metal pipe with optical connector and method of manufacturing the same

Abstract

To provide a metal pipe coated optical fiber cable with an optical connector capable of easily connecting optical fiber connectors to each other.SOLUTION: A metal pipe covered optical fiber cable with an optical connector according to the present invention includes a metal pipe covered optical fiber cable including a metal pipe through which an optical fiber core wire is inserted in an axial direction, and a connector portion including a ferrule through which the optical fiber core wire is inserted and fixed, and a ferrule holding portion in which one end portion in the axial direction is attached to an outer edge of the metal pipe in a state of not being fixed to the metal pipe and the other end portion is fixed to the ferrule.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The present invention relates to the technical field of fiber optic cables fitted with fiber optic connectors. [Background technology]

[0002] Known structures of optical fiber connectors to be attached to optical fiber cables include an optical fiber cord or an optical fiber cable in which a tensile strength member (a tensile strength fiber such as Kevlar (registered trademark)) is wound around the optical fiber core and an outer sheath (polyurethane, polyethylene, PVC (Polyvinyl Chloride), etc.) is formed around the outer periphery, with an optical fiber connector attached to the tip of the optical fiber cord or cable.

[0003] The optical fiber connector includes a ferrule through which an optical fiber core is inserted and fixed, a plug frame that houses the ferrule, a stop ring that houses a spring that biases the tip of the ferrule axially forward through an extrusion hole in the plug frame and engages and fixes it to the plug frame, and a boot that fits over the rear end of the stop ring to protect the optical fiber cord or optical fiber cable. The tensile member of the optical fiber cord or optical fiber cable is crimped and fixed to the rear end of the stop ring via a crimping ring, and the outer jacket is crimped and fixed to the rear end of the crimping ring via another ring.

[0004] On the other hand, metal tube-covered optical fiber cables with optical fiber cores inserted therein are known, but because metal tube-covered optical fiber cables do not have a tensile strength member made of high-tensile fiber, it is not possible to attach an optical fiber connector with the above structure.

[0005] For this reason, known means for attaching an optical fiber connector to such a metal tube-covered optical fiber cable include a means for flattening a portion of the metal tube and providing flat portions of the metal tube at both ends of the penetration portion of the stop ring to secure the connector (Patent Document 1), a means for securing the metal tube to the stop ring via a retainer ring and a stopper having a tapered surface (Patent Document 2), and a means for crimping the end of the stop ring from above the metal tube to secure the metal tube and the stop ring (Patent Document 3).

[0006] Optical fiber connectors are connected to each other via an adapter. Optical fiber cords or cables are physically connected (physical contact) when the ferrules on both sides are butted together by a spring built into the optical fiber connector.

[0007] To reduce the effect of light returning due to reflection at the mating surfaces of the ferrules, angled polishing (APC (Angled Physical Contact) polishing) is performed, in which the end faces of the ferrules are polished at an angle. In order to butt together angled ferrules, the directions of the ferrule tips must be aligned before connection can be made.

[0008] The flange of the ferrule has a groove cut in the rotational direction of the axis, for example, which engages with a protrusion formed on the inner wall surface of the plug frame. When attaching an obliquely polished ferrule, the orientation of the ferrule must be determined before attaching it to the plug frame, but there is a risk that the ferrule will rotate relative to the axial direction during the attachment process and be attached to the plug frame in the wrong orientation.

[0009] Known means for positioning a ferrule relative to such a plug frame include a means for making the flange shape of the ferrule asymmetrical in the vertical direction to easily align the vertical direction when assembling it into the plug frame (Patent Document 4), and a means for integrating the ferrule, optical fiber core, and optical cable with a heat-shrink tube to fix the rotational positional relationship with respect to the axial direction (Patent Document 5). [Prior art documents] [Patent documents]

[0010] [Patent Document 1] Japanese Patent Application Publication No. 5-127046 [Patent Document 2] Japanese Patent Application Publication No. 5-40212 [Patent Document 3] Japanese Patent Application Publication No. 5-11144 [Patent Document 4] Japanese Patent Application Laid-Open No. 2011-118348 [Patent Document 5] Japanese Patent Application Laid-Open No. 2017-106985 Summary of the Invention [Problem to be solved by the invention]

[0011] However, if the flange shape of the ferrule is asymmetrical from top to bottom and the plug frame is also shaped to match the flange, standardized optical fiber connectors cannot be used and custom-made products must be prepared, which can be expensive and difficult to obtain.

[0012] Furthermore, if the ferrule, optical fiber core, and optical fiber cable are integrated using a heat-shrinkable tube, standard products can be used, but when the ferrules are butted together, there is no spring return (room for springback), which hinders the degree of adhesion of the butt joint, and there is a risk of increased connection loss.

[0013] For these reasons, when attaching an optical fiber connector to a metal tube-covered optical fiber cable, there is a demand for a means for easily connecting optical fiber connectors to each other via an adapter.

[0014] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a metal tube covered optical fiber cable with optical connectors that allows optical fiber connectors to be easily connected to each other by positioning the ferrules. [Means for solving the problem]

[0015] The metal-tube-covered optical fiber cable with optical connector according to the present invention has a metal tube through which an optical fiber core is inserted in the axial direction, and comprises a connector portion having a ferrule through which the optical fiber core is inserted and fixed, and a ferrule holding portion having one end in the axial direction attached to the outer edge of the metal tube so as to be movable axially relative to the metal tube, and the other end fixed to the ferrule. This prevents the springback of each ferrule from being hindered when the ferrules are butted together to connect two metal tube covered optical fiber cables.

[0016] In the above-mentioned metal tube-covered optical fiber cable with optical connector, the cross-sectional shape perpendicular to the axis of all or part of the overlapping portion between the metal tube and the ferrule holding portion is considered to be a shape that prevents rotation of the ferrule holding portion relative to the metal tube in the axial direction. This prevents the ferrule fixed to the ferrule holding portion from rotating in the axial direction.

[0017] In the above-mentioned metal tube-covered optical fiber cable with optical connector, an optical fiber protection tube with the optical fiber core inserted therethrough is inserted inside the metal tube, and one end of the optical fiber protection tube is thought to protrude from the metal tube. As a result, the optical fiber core is inserted into the optical fiber protection tube protruding from the metal tube, and even if the optical fiber core comes into contact with the edge of the optical fiber protection tube, it will not be damaged.

[0018] In the above-mentioned metal tube-covered optical fiber cable with optical connector, it is conceivable that the opening surface at the other end of the optical fiber protection tube is shaped to be inclined with respect to the axial direction. This reduces the contact area of ​​the optical fiber protection tube with the cross section of the metal tube-covered optical fiber cable with optical connector, making it easier to insert the optical fiber protection tube into the metal tube while inserting the optical fiber core through it.

[0019] The method for manufacturing a metal tube-covered optical fiber cable with an optical connector according to the present invention is a method for manufacturing a metal tube-covered optical fiber cable with an optical connector, the metal tube-covered optical fiber cable having a metal tube through which an optical fiber core is inserted in the axial direction, the method comprising a connector portion having a ferrule for inserting and fixing the optical fiber core, and a ferrule holding portion having an insertion hole extending in the axial direction for inserting the metal tube, the method comprising the steps of: attaching one axial end of the ferrule holding portion to the outer edge of the metal tube in a state where it is movable in the axial direction relative to the metal tube; and fixing the other axial end of the ferrule holding portion to the ferrule. The metal-tube-covered optical fiber cable with optical connector manufactured by this manufacturing method also has the same effects as the metal-tube-covered optical fiber cable with optical connector according to the present invention described above. [Effects of the Invention]

[0020] According to the present invention, metal tube-covered optical fiber cables with optical connectors can be easily connected to each other. [Brief explanation of the drawings]

[0021] [Figure 1] 1 is a perspective view of a tip end of a metal tube-covered optical fiber cable with an optical connector according to an embodiment; [Figure 2] 1 is a cross-sectional view of a metal tube-covered optical fiber cable according to an embodiment. [Figure 3] 1 is an exploded perspective view of an optical fiber connector according to an embodiment. [Figure 4] 1 is an explanatory diagram of the connection between metal tube-covered optical fiber cables with optical connectors according to an embodiment. [Figure 5]3A to 3C are explanatory diagrams showing the manufacturing process of a metal tube-covered optical fiber cable with an optical connector according to an embodiment. [Figure 6] 3A to 3C are explanatory diagrams showing the manufacturing process of a metal tube-covered optical fiber cable with an optical connector according to an embodiment. [Figure 7] 3A to 3C are explanatory diagrams showing the manufacturing process of a metal tube-covered optical fiber cable with an optical connector according to an embodiment. [Figure 8] 5A and 5B are cross-sectional views of the ferrule holding portion before and after crimping after mounting in the embodiment. [Figure 9] 3A to 3C are explanatory diagrams showing the manufacturing process of a metal tube-covered optical fiber cable with an optical connector according to an embodiment. [Figure 10] 3A to 3C are explanatory diagrams showing the manufacturing process of a metal tube-covered optical fiber cable with an optical connector according to an embodiment. [Figure 11] 3A to 3C are explanatory diagrams showing the manufacturing process of a metal tube-covered optical fiber cable with an optical connector according to an embodiment. [Figure 12] 3A to 3C are explanatory diagrams showing the manufacturing process of a metal tube-covered optical fiber cable with an optical connector according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0022] Hereinafter, embodiments of the present invention will be described in the following order. <1. Structure of Metallic Tube Covered Optical Fiber Cable with Optical Connector> <2. How to connect a metal tube-covered optical fiber cable with an optical connector> <3. Manufacturing process of metal tube covered optical fiber cable with optical connector> <4. Summary and Modifications>

[0023] The various components shown in the drawings referred to in the description are only essential components of the present invention, and the drawings are merely schematic, and the relationship between thickness and planar dimensions of each structure, ratios, etc. are merely examples. Furthermore, the components shown in the drawings can be modified in various ways depending on the design, etc., as long as they do not deviate from the technical concept of the present invention. Furthermore, once a configuration has been explained, the same reference numerals may be used and explanations thereof may be omitted. Furthermore, the present invention is not limited to the present embodiment, and modifications and improvements within the scope of achieving the object of the present invention are included in the present invention.

[0024] <1. Structure of Metallic Tube Covered Optical Fiber Cable with Optical Connector> The configuration of a metal tube-covered optical fiber cable 100 with an optical connector according to an embodiment will be described with reference to Fig. 1 to Fig. 3. Fig. 1 is a perspective view of the tip of the metal tube-covered optical fiber cable 100 with an optical connector. As shown in Fig. 1, the metal tube-covered optical fiber cable 100 with an optical connector has a metal tube-covered optical fiber cable 1 and an optical fiber connector 2, and the optical fiber connector 2 is connected to the tip of the metal tube-covered optical fiber cable 1.

[0025] In the following description, the front and rear directions are expressed with the front end of the metal tube covered optical fiber cable 1 to which the optical fiber connector 2 is connected being the front.

[0026] The metal tube covered optical fiber cable 1 is a metal tube covered optical fiber cable in which an optical fiber core is inserted, and among them, an armored metal tube covered optical fiber cable in which an armor wire is wound around a metal tube is also used. In this embodiment, an example will be described in which the metal-tube-covered optical fiber cable 1 is an armored metal-tube-covered optical fiber cable.

[0027] 2 is a cross-sectional view (cross-sectional view taken along line XX in FIG. 1) of the metal tube-covered optical fiber cable 1 according to the present embodiment. As shown in FIG. 2, the metal tube-covered optical fiber cable 1 includes an optical fiber core 3, a metal tube 4, an armor wire 5, a holding winding tape 6, and an outer jacket 7.

[0028] The metal tube-covered optical fiber cable 1 has a metal tube 4 (e.g., stainless steel, nickel alloy, copper, titanium, aluminum, etc.) with an optical fiber core 3 inserted therein and multiple armor wires 5 (e.g., iron wire, steel wire, etc.) wound around it, a holding winding tape 6 is arranged on the armor wires 5, and an outer jacket 7 (e.g., polyurethane, polyester, polyethylene, nylon, vinyl chloride resin, etc.) is formed on the holding winding tape 6. The inside of the metal tube 4 is filled with a fluid resin (e.g., resin such as epoxy resin or urethane resin, or synthetic oil of hydrocarbon polymer, etc.).

[0029] Next, an SC (Square-shaped Connector) connector will be described as an example of the optical fiber connector 2. Note that although an SC connector will be described as an example in this embodiment, the optical fiber connector 2 can be applied to various connectors, such as an MU (Miniature Universal Coupling) connector and an LC (Local Connector) connector.

[0030] 3 is an exploded perspective view of the optical fiber connector 2 in the metal tube-covered optical fiber cable with optical connector 100 according to the present embodiment. As shown in FIG. 3, the optical fiber connector 2 has a ferrule 8, a ferrule holding portion 9, a stop ring 10, a spring 11, a plug frame 12, a crimping ring 13, a ring 14, a protective tube 15, a boot 16, and a knob (housing) 17.

[0031] The ferrule 8 has a wire insertion portion 8a, an insertion portion 8b, and a flange portion 8c. The core wire insertion portion 8a has an insertion hole 8d extending in the axial direction for inserting the optical fiber core wire 3 of the metal tube-coated optical fiber cable 1 therethrough. An insertion hole 8e extending in the axial direction is formed in the insertion portion 8b. The insertion portion 8b is provided on the rear side of the core wire insertion portion 8a, and the insertion hole 8e communicates with the insertion hole 8d. The diameter of the insertion hole 8d is smaller than the diameter of the insertion hole 8e. The flange portion 8c is provided in an annular shape on the outer peripheral surface of the core wire insertion portion 8a.

[0032] The ferrule holding portion 9 is deformable by pressure or the like and has a small cylindrical portion 9a and a large cylindrical portion 9b. The small cylindrical portion 9a is formed in a generally cylindrical shape and has an insertion hole 9c extending in the axial direction. The large cylindrical portion 9b is also formed in a generally cylindrical shape and has an insertion hole 9d extending in the axial direction. The large cylindrical portion 9b is provided behind the small cylindrical portion 9a, and the insertion holes 9c and 9d are connected to each other. The diameter of the insertion hole 9d in the large cylindrical portion 9b is larger than the diameter of the insertion hole 9c in the small cylindrical portion 9a. The front end 9e of the small cylindrical portion 9a is inserted into and fixed in the insertion hole 8e of the ferrule 8. The optical fiber 3 of the metal tube-covered optical fiber cable 1 is inserted into the insertion hole 9c, and the metal tube 4 is inserted into the insertion hole 9d. The ferrule holding portion 9 is preferably made of a metallic material.

[0033] The stop ring 10 has a housing portion 10a and an insertion portion 10b. The housing portion 10a has a generally cylindrical shape and an insertion hole 10c extending in the axial direction. The insertion portion 10b also has a generally cylindrical shape and an insertion hole 10d extending in the axial direction. The insertion portion 10b is provided on the rear side of the accommodating portion 10a, and the insertion holes 10c and 10d are connected to each other. The diameter of the insertion hole 10c of the accommodating portion 10a is larger than the diameter of the insertion hole 10d of the insertion portion 10b. A spring 11 is accommodated in the insertion hole 10c of the accommodating portion 10a, and the spring 11 biases the ferrule 8 forward by abutting against the rear end of the flange portion 8c of the ferrule 8.

[0034] The plug frame 12 has an insertion hole 12a extending in the axial direction, and the plug frame 12 is attached to the stop ring 10 by inserting the receiving portion 10a of the stop ring 10 into the insertion hole 12a from the rear side. At this time, the ferrule 8 is inserted into the insertion hole 12a, and the front end of the flange portion 8c of the ferrule 8 abuts against a support portion (not shown) provided in the insertion hole 12a, thereby restricting the ferrule 8 from moving forward. When the plug frame 12 is attached to the stop ring 10 , the ferrule 8 is urged forward by the spring 11 , and the tip 8 f of the ferrule 8 projects from the opening 12 b of the plug frame 12 .

[0035] The crimping ring 13 has a small diameter portion 13a and a large diameter portion 13b. The small diameter portion 13a is formed in a generally cylindrical shape and has an insertion hole 13c extending in the axial direction. The large diameter portion 13b is also formed in a generally cylindrical shape and has an insertion hole 13d extending in the axial direction. The diameter of the large diameter portion 13b is larger than the diameter of the small diameter portion 13a. The small diameter portion 13a is provided behind the large diameter portion 13b, and the insertion holes 13c and 13d are in communication with each other. The metal tube 4 of the metal tube-coated optical fiber cable 1 is inserted through the insertion holes 13c and 13d. The insertion portion 10b of the stop ring 10 is inserted into the insertion hole 13d of the large diameter portion 13b.

[0036] The armor wire 5 of the metal tube-coated optical fiber cable 1 is placed on the outer periphery of the small diameter portion 13a of the crimping ring 13, and the annular ring 14 is attached so as to press the armor wire 5 against the small diameter portion 13a.

[0037] The protective tube 15 is formed in a generally cylindrical shape extending in the axial direction. An opening surface 15a at the rear end of the protective tube 15 is shaped to be inclined with respect to the axial direction. The protective tube 15 is inserted into the metal tube 4 of the metal tube-covered optical fiber cable 1 from the end of the opening surface 15a, and the optical fiber 3 is inserted into the insertion hole 15b of the protective tube 15. The protective tube 15 is preferably made of a material that maintains a rigid shape with resin or the like, such as PEEK (Poly Ether Ether Ketone) resin, etc. The protective tube 15 has a rigid shape, so it protects the optical fiber 3 inside, and since it is less hard than the optical fiber 3, there is no risk of the optical fiber 3 being damaged even if it comes into contact with the end portion.

[0038] The boot 16 has an insertion hole 16a extending in the axial direction. The metal tube-covered optical fiber cable 1 is inserted into the rear end of the insertion hole 16a, and the large diameter portion 13b of the crimping ring 13 is inserted into the front end.

[0039] The knob (housing) 17 has an insertion hole 17a extending in the axial direction, and the plug frame 12 is inserted from the rear side of the insertion hole 17a, and the knob (housing) 17 is attached to the plug frame 12 so as to cover the tip end of the boot 16.

[0040] <2. How to connect a metal tube-covered optical fiber cable with an optical connector> A method for connecting metal tube-covered optical fiber cables 100 with optical connectors according to an embodiment will be described with reference to Fig. 4. As shown in Fig. 4A, metal tube-covered optical fiber cables 100 with optical connectors, 100, 100 are connected to each other via an adapter 200.

[0041] The metal tube-covered optical fiber cables 100 with optical connectors are inserted into the adapter 200, and the ferrules 8 are butted together as shown in Fig. 4B in a state where spring back is ensured by the springs 11 (not shown) built into each optical fiber connector 2, thereby achieving physical contact. This allows the optical fiber cores 3 inserted into the insertion holes 8d provided in each of the ferrules 8 to be connected. At this time, the front end faces 8g of both ferrules 8 are polished (PC (Physical Contact) polished) so as to be parallel to the direction orthogonal to the axis, for example.

[0042] 4C, angled polishing (APC (Angled Physical Contact) polishing) may be performed to polish each front end face 8g of the ferrule 8 at an angle in order to reduce the influence of returning light due to reflection at the mating surfaces of the ferrules 8. The front end faces 8g are polished so as to be inclined at an angle of 8 degrees relative to the direction perpendicular to the axis, for example, to form polished surfaces 8h. When ferrules 8 having such polished surfaces 8h are butted together, the ferrules 8 can be easily connected by fixing the orientation of the polished surfaces 8h of the ferrules 8 before connecting them. Therefore, in this embodiment, a metal tube-covered optical fiber cable 100 with an optical connector in which the ferrule 8 is positioned relative to the knob (housing) 17 and a manufacturing method thereof will be described.

[0043] <3. Manufacturing process of metal tube covered optical fiber cable with optical connector> A manufacturing process for a metal tube-covered optical fiber cable 100 with an optical connector according to an embodiment of the present invention will be described with reference to Fig. 5 to Fig. 12. Figs. 5 to 7 and 9 to 12 show front views of the side 2a of the optical fiber connector 2 of the metal tube-covered optical fiber cable 100 with an optical connector shown in Fig. 1, and for ease of explanation, the ferrule 8, ferrule holding portion 9, stop ring 10, crimping ring 13, ring 14, and tape 21, which will be described later, are shown as cross sections in the axial direction taken from a direction perpendicular to the axis.

[0044] 5A, the jacket 7 of the metal tube-coated optical fiber cable 1 is stripped off, and a ring 14 is fitted over the metal tube 4 so as to cover the multiple armor wires 5 provided around the metal tube 4. Each armor wire 5 is folded back at the front edge 14a of the ring 14.

[0045] Thereafter, the metal tube 4 exposed by folding back each armor wire 5 is fitted with the crimping ring 13, the stop ring 10, and the spring 11, which are components of the optical fiber connector 2, in that order.

[0046] The insertion portion 10b of the stop ring 10 is inserted into the insertion hole 13d of the crimping ring 13, and the stop ring 10 is inserted into the crimping ring 13. The spring 11 is housed in the insertion hole 10c of the stop ring 10.

[0047] 5B, each folded armor wire 5 is temporarily secured by wrapping vinyl tape 20 around the outer jacket. Then, the front side of the metal tube 4 is cut to expose the optical fiber core 3.

[0048] 6A, the optical fiber core 3 is inserted into the insertion hole 15b of the protective tube 15, and the protective tube 15 is inserted into the metal tube 4. The protective tube 15 is inserted into the metal tube 4 from the end of the opening surface 15a, and is positioned so that the front end 15c protrudes forward from the metal tube 4.

[0049] 6B, the front portion 4a of the metal tube 4 into which the protective tube 15 has been inserted is crimped to fix the protective tube 15 to the metal tube 4. This fixes the protective tube 15 to the metal tube 4 with the front end 15c protruding forward from the metal tube 4, preventing the optical fiber 3 from coming into contact with the edge of the metal tube 4 and being damaged.

[0050] Next, as shown in FIG. 7A, the optical fiber 3 is inserted into the insertion hole 9c of the ferrule holding portion 9, and then the front portion 4a of the metal tube 4 is inserted into the insertion hole 9d of the ferrule holding portion 9.

[0051] 8A is a cross-sectional view (YY cross-sectional view of FIG. 7A) showing a state in which the front portion 4a is inserted into the insertion hole 9d. As shown in FIG. 8A, a gap is provided between the front wall portion 9e of the hollow portion of the ferrule holding portion 9 and the front portion 4a of the metal tube 4.

[0052] Next, as shown in FIG. 7B, the overlapping portion 9f of the front portion 4a of the metal tube 4 and the large cylindrical portion 9b of the ferrule holding portion 9 is crimped, and all or part of the overlapping portion 9f of the front portion 4a of the metal tube 4 and the large cylindrical portion 9b of the ferrule holding portion 9 is formed into a non-circular shape that is approximately the same in the direction perpendicular to the axis.

[0053] 8B is a cross-sectional view (ZZ cross-sectional view of FIG. 7B) of the overlapping portion 9f of the front portion 4a and the large cylindrical portion 9b after crimping. As shown in FIG. 8B, crimping is performed from above the large cylindrical portion 9b, for example, to form the large cylindrical portion 9b and the front portion 4a into a substantially identical rectangular shape. This prevents the ferrule holding portion 9 from rotating in the axial direction relative to the metal tube 4. The crimping process may be performed by crimping the ferrule holding portion 9 and the metal tube 4 simultaneously, or by crimping the ferrule holding portion 9 and the metal tube 4 separately.

[0054] Here, the method for forming the large cylindrical portion 9b and the front portion 4a does not have to be crimping, and various other processing methods may be used, and the formed shape may not only be rectangular, but also polygonal such as triangular or hexagonal, or elliptical, as long as it is a shape that prevents rotation of the metal tube 4 in the axial direction relative to the ferrule holding portion 9.

[0055] Furthermore, when the large cylindrical portion 9b and the front portion 4a are formed, the protective tube 15 is hardly deformed because it is fixed in close contact with the metal tube 4. As a result, the inserted optical fiber 3 is protected by the protective tube 15.

[0056] Even after crimping, a gap remains between the tip side wall 9e of the hollow part of the ferrule holding part 9 and the front part 4a of the metal tube 4. In this way, the metal tube 4 and the ferrule holding part 9 are only deformed to the extent that they do not fixate each other, so that the ferrule holding part 9 can move in the axial direction relative to the metal tube 4 even when rotation relative to the metal tube 4 is restricted. Furthermore, a space is secured between the end of the metal tube 4 (the end of the protective tube 15) and the bottom surface of the inner cylindrical part of the large cylindrical part 9b of the ferrule holding part 9. This space ensures a margin for the spring 11 to spring back.

[0057] After the metal tube 4 and the ferrule holding part 9 are crimped, the rear end of the ferrule holding part 9 and the metal tube 4 are temporarily fastened with tape 21 to prevent the ferrule holding part 9 from moving relative to the metal tube 4, as shown in Figure 7B.

[0058] 9A, the optical fiber 3 is inserted into the insertion hole 8d of the ferrule 8 and fixed therein with an adhesive or the like, and the front end 9e of the small cylindrical portion 9a is inserted into the insertion hole 8e and fixed therein with an adhesive or the like. Then, the excess optical fiber 3a protruding from the front end face 8g of the ferrule 8 is cut off.

[0059] Then, as shown in FIG. 9B, the front end surface 8g of the ferrule 8 is inclined and subjected to APC polishing to form a polished surface 8h.

[0060] In the manufacturing process described above, the metal tube 4 and the ferrule holding part 9 are crimped together, thereby preventing the ferrule holding part 9 from rotating relative to the metal tube 4. Therefore, by fixing the ferrule holding part 9 to the ferrule 8, the ferrule 8 is also prevented from rotating relative to the metal tube 4. Accordingly, the orientation of the polished surface 8h of the ferrule 8 around the axis of the metal tube 4 is determined.

[0061] After the integration, the tape 21 that temporarily fastened the ferrule holding portion 9 to the metal tube 4 is removed, as shown in FIG. 10A.

[0062] Thereafter, the stop ring 10 is moved to the tip of the ferrule 8 and engaged and fixed with the plug frame 12. When the plug frame 12 is attached to the stop ring 10, the ferrule 8 is urged forward by the spring 11, and the tip 8f of the ferrule 8 protrudes from the opening 12b of the plug frame 12. Furthermore, by the above-described manufacturing process, the ferrule 8 is prevented from rotating relative to the metal tube 4, and therefore the orientation of the polished surface 8h of the ferrule 8 around the axis of the plug frame 12 is also determined.

[0063] This ensures that the ferrules 8 will spring back backward when the tip faces (polished faces 8h) of the ferrules 8 are butted together to connect metal-tube-coated optical fiber cables 100 with optical connectors as shown in Figure 4.

[0064] 10B, the crimping ring 13 is crimped to be integrally fixed to the stop ring 10. An adhesive is applied to the outer periphery of the small diameter portion 13a of the crimping ring 13. Then, the vinyl tape 20 that temporarily fastened the multiple armor wires 5 is removed, and each armor wire 5 is stretched forward and placed around the outer periphery of the small diameter portion 13a.

[0065] Then, as shown in FIG. 11A, the ring 14 is moved to the small diameter portion 13a and crimped onto the small diameter portion 13a, thereby fixing the ring 14, the armoring wire 5, and the crimp ring 13 together.

[0066] 11B, a protective tape 22 is then wrapped around the fixed armor wire 5 and shaped to have the same outer diameter as the outer diameter of the jacket 7 of the metal-tube-coated optical fiber cable 1. A heat-shrinkable tube that has been fitted over the jacket 7 so as to cover the front end 7a of the jacket 7, the tape-wrapped armor wire 5, the ring 14, and the small diameter portion 13a of the crimping ring 13 is shrunk to form a boot 16. Note that a standardized boot for an optical fiber connector can also be used if the outer diameter of the metal-tube-coated optical fiber cable 1 is suitable.

[0067] Finally, as shown in FIG. 12, the knob (housing) 17 is attached to the plug frame 12. Through the above manufacturing steps, the metal tube-covered optical fiber cable 100 with optical connector according to this embodiment is manufactured.

[0068] <4. Summary and Modifications> The metal tube-covered optical fiber cable 100 with optical connector, which has the metal tube 4 through which the optical fiber core 3 of the above embodiment is inserted in the axial direction, is provided with a connector portion (optical fiber connector 2) having a ferrule 8 through which the optical fiber core 3 is inserted and fixed, and a ferrule holding portion 9 whose one end in the axial direction (the large cylindrical portion 9b side) is attached to the outer edge of the metal tube 4 so as to be movable in the axial direction relative to the metal tube 4, and whose other end (the small cylindrical portion 9a side) is fixed to the ferrule 8 (see Figure 7). As a result, when the ferrules 8 are butted together to connect two metal tube-covered optical fiber cables 100 with optical connectors as shown in FIG. 4, the spring back of each ferrule 8 is not hindered. Therefore, the impact when the ferrules 8 are butted together can be alleviated, and the metal tube-covered optical fiber cables 100 with optical connectors can be easily connected to each other while avoiding damage to the ferrules 8.

[0069] In the metal tube-coated optical fiber cable 100 with optical connector of this embodiment, the cross-sectional shape perpendicular to the axis of all or part of the overlapping portion 9f between the metal tube 4 and the ferrule holding portion 9 is shaped to prevent rotation of the ferrule holding portion 9 relative to the metal tube 4 in the axial direction (see Figures 7 and 8). As a result, the ferrule 8 fixed to the ferrule holding portion 9 does not rotate in the axial direction. Therefore, after the direction of the ferrule 8 is determined and the ferrule 8 is polished obliquely, it can be attached to the plug frame 12 without rotating the direction of the ferrule 8, and the optical fiber connector 2 can be assembled without making a mistake in the direction of the polished surface 8h of the ferrule 8.

[0070] In the metal tube-covered optical fiber cable 100 with optical connector of this embodiment, a protective tube 15 with an optical fiber core 3 inserted therethrough is inserted inside the metal tube 4, and one end (front end 15c) of the protective tube 15 protrudes from the metal tube 4 (see Figure 6). As a result, the optical fiber 3 is inserted into the protective tube 15 protruding from the metal tube 4 , and the optical fiber 3 does not come into contact with the edge of the metal tube 4 . Therefore, the optical fiber 3 is protected by the protective tube 15, and the optical fiber 3 can be prevented from coming into contact with the edge of the metal tube 4 and being damaged.

[0071] In the metal tube-covered optical fiber cable 100 with optical connector of this embodiment, the opening surface 15a at the other end of the protective tube 15 is shaped to be inclined with respect to the axial direction (see FIGS. 3 and 6). This reduces the contact area of ​​the protective tube 15 with the cross section of the metal tube 4. Since the opening surface 15a of the protective tube 15 is formed at an angle, the protective tube 15 can be easily inserted into the metal tube 4, and it becomes easy to insert the protective tube 15 into the metal tube 4 while inserting the optical fiber core 3. Therefore, the efficiency of the work in manufacturing the metal tube-covered optical fiber cable 100 with optical connector can be improved.

[0072] Furthermore, the manufacturing method of the metal tube-covered optical fiber cable 100 with optical connector described above as an embodiment includes a step of attaching one end (the large cylindrical portion 9b side) of the ferrule holding portion 9 in the axial direction to the outer edge of the metal tube 4 so that it is movable in the axial direction relative to the metal tube 4, and a step of fixing the other end (the small cylindrical portion 9a side) of the ferrule holding portion 9 in the axial direction to the ferrule 8 (see Figures 8B and 9). The metal tube-covered optical fiber cable 100 with optical connector manufactured by such a manufacturing method can also achieve the same functions and effects as the metal tube-covered optical fiber cable 100 with optical connector according to the present embodiment described above.

[0073] In this embodiment, a metal tube-covered optical fiber cable having an armored wire 5 is exemplified, and therefore the armored wire 5 is crimped and fixed to the crimping ring 13. However, when using a metal tube-covered optical fiber cable without an armored wire 5, various means used in conventional technology (such as a means of flattening a portion of the metal tube and providing flat portions of the metal tube at both ends of the penetration portion of the stop ring to fix the metal tube, a means of fixing the metal tube to the stop ring via a retainer ring and stopper having a tapered surface, or a means of crimping the end of the stop ring from above the metal tube to fix the metal tube and the stop ring) may be used.

[0074] In addition, in the present embodiment, an example has been described in which the stripped jacket 7 is cut in the manufacturing process of the metal tube-coated optical fiber cable with optical connector 100, but the jacket 7 may not be cut. In this case, the stripped jacket 7 may be crimped and fixed to the rear end of the ring 14 via an annular member or the like.

[0075] Finally, the effects described in this disclosure are merely examples and are not limiting, and other effects may be achieved, or some of the effects described in this disclosure may be achieved. Furthermore, the embodiments described in this disclosure are merely examples, and the present invention is not limited to the above-described embodiments. Therefore, various modifications other than those described above are naturally possible depending on the design, etc., as long as they do not deviate from the technical concept of the present invention. Furthermore, not all of the combinations of the configurations described in the embodiments are necessarily essential to solving the problem. [Explanation of symbols]

[0076] 1 Metallic tube covered optical cable 2. Fiber Optic Connector 3 Optical fiber core 4 metal tube 5 Exterior Wire 7 Outer cover 8 ferrules 9 Ferrule holder 10 Stop ring 11 Spring 12 Plug Frame 13 Crimping ring 14 Ring 15 Protective tube 15a Opening surface 15c Front end 16 Boots 17 Knob (housing) 100 Metallic tube-covered optical fiber cable with optical connector

Claims

1. a metal tube-covered optical fiber cable having a metal tube through which an optical fiber core is inserted in the axial direction; a connector portion having a ferrule through which the optical fiber core is inserted and fixed, and a ferrule holding portion having one end in the axial direction attached to the outer edge of the metal tube without being fixed to the metal tube, and the other end fixed to the ferrule. Metal tube coated optical fiber cable with optical connector.

2. The outer edge of the metal pipe is inserted into the one end of the ferrule holding portion in the axial direction with a gap therebetween, so that the one end is not fixed to the metal pipe.

2. The metal tube-covered optical fiber cable with optical connector according to claim 1.

3. The connector portion includes a restricting member that is fixed to the outer periphery of the metal tube-covered optical fiber cable and restricts movement of the ferrule toward the tip side of the connector portion.

3. The metal tube-covered optical fiber cable with optical connector according to claim 1.

4. The connector portion is a stop ring fixed to the outer periphery of the metal tube-covered optical fiber cable; a plug frame fixed to the stop ring and restricting movement of the ferrule toward the tip end of the connector portion.

3. The metal tube-covered optical fiber cable with optical connector according to claim 1.

5. The ferrule has a flange portion protruding from an outer circumferential surface, The plug frame includes an insertion hole through which the ferrule is inserted, and a support portion that is provided on a surface that forms the insertion hole and abuts against the flange portion to restrict movement of the ferrule toward the tip side of the connector portion.

5. The metal tube-covered optical fiber cable with optical connector according to claim 4.

6. a metal tube-covered optical fiber cable having a metal tube through which an optical fiber core is inserted in the axial direction; a connector portion having a ferrule for inserting and fixing the optical fiber core wire and a ferrule holding portion having an insertion hole extending in the axial direction for inserting the metal tube; A method for manufacturing a metal tube-covered optical fiber cable with an optical connector, comprising: attaching one end of the ferrule holding portion in the axial direction to an outer edge of the metal tube without fixing the other end to the metal tube; and fixing the other end of the ferrule holding portion in the axial direction to the ferrule. A method for manufacturing a metal tube-covered optical fiber cable with an optical connector.

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