JP2026001200A - Metallic tube covered optical fiber cable with optical connector, and method for manufacturing the metallic tube covered optical fiber cable with optical connector - Google Patents

Abstract

[Problem] To provide a metal-tube-covered optical fiber cable with optical connectors that allows easy connection between optical fiber connectors. [Solution] The metal-tube-covered optical fiber cable with optical connectors of the present invention comprises a metal-tube-covered optical fiber cable having a metal tube through which an optical fiber core is inserted in the axial direction, a ferrule through which the optical fiber core is inserted and fixed, and a connector portion having a ferrule holding portion whose one end in the axial direction is attached to the outer edge of the metal tube without being fixed to the metal tube and whose other end is fixed to the ferrule. [Selected Figure] Figure 7

Description

The present invention relates to the technical field of optical fiber cables equipped with optical fiber connectors.

A known structure for an optical fiber connector attached to an optical fiber cable is an optical fiber cord or 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 jacket (polyurethane, polyethylene, PVC (Polyvinyl Chloride), etc.) is formed around the outer periphery, with the optical fiber connector attached to the tip of the optical fiber cord or cable.

An optical fiber connector comprises a ferrule into 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 the plug frame's protrusion hole and engages and fixes it to the plug frame, and a boot that fits over the rear end of the stop ring and protects the optical fiber cord or optical fiber cable. The tensile strength 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.

Metal-tube-covered optical fiber cables with optical fiber cores inserted are also known, but because metal-tube-covered optical fiber cables do not have a tensile strength member made of high-tensile fiber, optical fiber connectors with the above structure cannot be attached.

For this reason, known methods for attaching an optical fiber connector to such a metal-tube-covered optical fiber cable include a method in which a portion of the metal tube is flattened and flattened portions of the metal tube are provided on both ends of the penetration portion of the stop ring for fastening (Patent Document 1), a method in which the metal tube is fastened to the stop ring via a retainer ring and a stopper with tapered surfaces (Patent Document 2), and a method in which the end of the stop ring is crimped onto the metal tube to fasten the metal tube and the stop ring (Patent Document 3).

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 ends are butted together by a spring built into the optical fiber connector.

To reduce the effect of reflected light 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 tips of the ferrules must be aligned before connection can be made.

The ferrule flange has a groove cut in the direction of rotation of the axis, for example, which engages with a protrusion formed on the inner wall surface of the plug frame. When installing a diagonally polished ferrule, the orientation of the ferrule must be determined before it can be attached to the plug frame. However, there is a risk that the ferrule may rotate relative to the axis during the installation process, resulting in it being installed in the wrong orientation on the plug frame.

Known methods for positioning a ferrule relative to such a plug frame include making the ferrule flange asymmetrical in the vertical direction to easily align the vertical orientation when assembling it into the plug frame (Patent Document 4), and integrating the ferrule, optical fiber core, and optical cable with a heat-shrinkable tube to fix their rotational position relative to the axial direction (Patent Document 5).

Japanese Patent Application Publication No. 5-127046 Japanese Patent Application Publication No. 5-40212 Japanese Patent Application Publication No. 5-11144 JP 2011-118348 A JP 2017-106985 A

However, if the ferrule flange shape 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 a custom-made product must be prepared, which can be expensive and difficult to obtain.

Furthermore, if the ferrule, optical fiber core, and optical fiber cable are integrated using heat-shrink tubing, 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 at the butt joint, and there is a risk of increased connection loss.

For these reasons, there is a need for a means to easily connect optical fiber connectors to each other via an adapter when attaching optical fiber connectors to metal-tube-covered optical fiber cables.

The present invention aims 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.

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.

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.

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.

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.

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.

This invention makes it possible to easily connect metal-tube-covered optical fiber cables with optical connectors.

1 is a perspective view of a tip portion of a metal tube-covered optical fiber cable with an optical connector according to an embodiment; 1 is a cross-sectional view of a metal tube-covered optical fiber cable according to an embodiment. 1 is an exploded perspective view of an optical fiber connector according to an embodiment. 1 is an explanatory diagram of the connection between metal tube-covered optical fiber cables with optical connectors according to an embodiment. 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. 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. 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. 5A and 5B are cross-sectional views of the ferrule holding portion before and after crimping after mounting in the embodiment. 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. 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. 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. 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.

Hereinafter, embodiments of the present invention will be described in the following order.
<1. Configuration of a metal tube-covered optical fiber cable with an optical connector>
<2. Method of connecting 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>

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.

<1. Configuration of a metal tube-covered optical fiber cable with an 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 includes 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.

In the following description, the front and rear directions will be described with the tip of the metal tube-covered optical fiber cable 1 to which the optical fiber connector 2 is connected as the front.

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.

Figure 2 is a cross-sectional view (X-X cross-sectional view of Figure 1) of the metal-conduit-covered optical fiber cable 1 in this embodiment. As shown in Figure 2, the metal-conduit-covered optical fiber cable 1 includes an optical fiber core 3, a metal conduit 4, an armoring wire 5, a holding and wrapping tape 6, and an outer jacket 7.

A metal-tube-covered optical fiber cable 1 has multiple armor wires 5 (e.g., iron wire, steel wire, etc.) wound around a metal tube 4 (e.g., stainless steel, nickel alloy, copper, titanium, aluminum, etc.) through which an optical fiber core 3 is inserted. A holding winding tape 6 is placed on the armor wires 5, and an outer jacket 7 (e.g., polyurethane, polyester, polyethylene, nylon, polyvinyl 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., epoxy resin, urethane resin, synthetic oil of hydrocarbon polymer, etc.).

Next, the optical fiber connector 2 will be described using an SC (Square-shaped Connector) connector as an example. While the present embodiment uses an SC connector as an example, the optical fiber connector 2 can also be used with various other connectors, such as an MU (Miniature Universal Coupling) connector or an LC (Local Connector) connector.

Figure 3 is an exploded perspective view of the optical fiber connector 2 in the metal tube-covered optical fiber cable 100 with optical connector according to this embodiment. As shown in Figure 3, the optical fiber connector 2 includes a ferrule 8, a ferrule holder 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.

The ferrule 8 has a wire insertion portion 8a, an insertion portion 8b, and a flange portion 8c.
The core wire insertion portion 8 a has an insertion hole 8 d extending in the axial direction for inserting the optical fiber core wire 3 of the metal tube-covered optical fiber cable 1 .
The insertion portion 8b is formed with an insertion hole 8e extending in the axial direction. The insertion portion 8b is provided behind 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.

The ferrule holding portion 9 is deformable by pressure or the like and has a small cylindrical portion 9 a and a large cylindrical portion 9 b. The small cylindrical portion 9 a is formed in a generally cylindrical shape and has an insertion hole 9 c extending in the axial direction. The large cylindrical portion 9 b is also formed in a generally cylindrical shape and has an insertion hole 9 d 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 of the large cylindrical portion 9b is larger than the diameter of the insertion hole 9c of 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 core 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.

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 housing portion 10a, and the insertion holes 10c and 10d are connected to each other. The diameter of the insertion hole 10c of the housing portion 10a is larger than the diameter of the insertion hole 10d of the insertion portion 10b. A spring 11 is housed in the insertion hole 10c of the housing portion 10a, and the spring 11 abuts against the rear end of the flange portion 8c of the ferrule 8, thereby urging the ferrule 8 forward.

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 accommodating 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 .

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 connected to each other. The metal tube 4 of the metal tube-covered 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.

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.

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 inclined relative 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 softer in hardness 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.

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.

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.

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

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

4C , angled physical contact (APC) polishing is 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 at an angle of, for example, 8 degrees relative to the direction perpendicular to the axis, forming polished surfaces 8h.
When the 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. 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 method for manufacturing the same will be described.

<3. Manufacturing process of metal tube covered optical fiber cable with optical connector>
A manufacturing process for the 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 Figures 5 to 12. Figures 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 Figure 1, and for convenience 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.

As shown in Figure 5A, the jacket 7 of the metal-tube-coated optical fiber cable 1 is stripped away, and a ring 14 is fitted over the metal tube 4 to cover the multiple armored wires 5 arranged around the metal tube 4. Each armored wire 5 is folded back at the front edge 14a of the ring 14.

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

Insert the insertion portion 10b of the stop ring 10 into the insertion hole 13d of the crimping ring 13, and insert the stop ring 10 into the crimping ring 13. Also, place the spring 11 in the insertion hole 10c of the stop ring 10.

Next, as shown in Figure 5B, each folded armor wire 5 is temporarily secured by wrapping vinyl tape 20 around the outer sheath. The front side of the metal tube 4 is then cut to expose the optical fiber core 3.

Then, as shown in Figure 6A, the optical fiber core 3 is inserted through 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.

Next, as shown in Figure 6B, the front portion 4a of the metal tube 4 into which the protective tube 15 has been inserted is crimped to secure the protective tube 15 to the metal tube 4. This secures 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 core 3 from coming into contact with the edge of the metal tube 4 and causing damage.

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

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

Next, as shown in Figure 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, so that 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, but substantially uniform, shape perpendicular to the axis.

Figure 8B is a cross-sectional view (Z-Z cross-sectional view of Figure 7B) of the overlapping portion 9f of the front portion 4a and the large cylindrical portion 9b after crimping. As shown in Figure 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 rotation of the ferrule holding portion 9 relative to the metal tube 4 in the axial direction. The crimping process may be performed by crimping the ferrule holding portion 9 and the metal tube 4 simultaneously, or by crimping and deforming the ferrule holding portion 9 and the metal tube 4 separately.

Note that the large cylindrical portion 9b and the front portion 4a can be formed using various processing methods other than crimping, and the shapes they are formed into are not limited to squares; they can also be polygonal (triangles, hexagons, etc.), ellipses, etc., as long as they prevent rotation of the metal tube 4 in the axial direction relative to the ferrule holding portion 9.

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

Even after crimping, a gap is provided 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 in a state where rotation of the ferrule holding part 9 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.

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

Next, as shown in Figure 9A, the optical fiber core 3 is inserted into the insertion hole 8d of the ferrule 8 and secured with adhesive or the like, and the front end 9e of the small cylindrical portion 9a is inserted into the insertion hole 8e and secured with adhesive or the like. Then, any excess optical fiber core 3a protruding from the front end face 8g of the ferrule 8 is cut off.

Then, as shown in Figure 9B, APC polishing is performed to tilt the front end surface 8g of the ferrule 8 and create a polished surface 8h.

In the manufacturing process described above, the metal tube 4 and the ferrule holder 9 are crimped together, preventing the ferrule holder 9 from rotating relative to the metal tube 4. Therefore, by fixing the ferrule holder 9 to the ferrule 8, the ferrule 8 is also prevented from rotating relative to the metal tube 4. As a result, the orientation of the polished surface 8h of the ferrule 8 around the axis of the metal tube 4 is determined.

After integration, as shown in Figure 10A, the tape 21 temporarily fastening the ferrule holding portion 9 to the metal tube 4 is removed.

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 8 f of the ferrule 8 protrudes from the opening 12 b 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.

This ensures that the ferrules 8 do not spring back backward when the tip faces (polished surfaces 8h) of the ferrules 8 are butted together to connect two metal-tube-covered optical fiber cables 100 with optical connectors, as shown in Figure 4.

Next, as shown in Figure 10B, the crimping ring 13 is crimped to secure it integrally with the stop ring 10. 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 positioned around the outer periphery of the small diameter portion 13a.

Then, as shown in Figure 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, exterior wire 5, and crimp ring 13 together.

Then, as shown in Figure 11B, a protective tape 22 is wrapped around the fixed armor wire 5 and shaped to have the same outer diameter as the outer jacket 7 of the metal-tube-coated optical fiber cable 1. The boot 16 is shaped by shrinking a heat-shrinkable tube that has been fitted over the front end 7a of the armor wire 7, the tape-wrapped armor wire 5, the ring 14, and the small diameter portion 13a of the crimping ring 13. It is also possible to use a standardized optical fiber connector boot if the outer diameter of the metal-tube-coated optical fiber cable 1 is suitable.

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

<4. Summary and Modifications>
In the metal tube-covered optical fiber cable 100 with optical connector, which includes the metal tube 4 through which the optical fiber core 3 of the above embodiment is inserted in the axial direction, the cable includes 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).
This prevents the springback of each ferrule 8 from being hindered when the ferrules 8 are butted together to connect two metal-tube-covered optical fiber cables 100 with optical connectors as shown in FIG.
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.

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 obliquely polished, it can be attached to the plug frame 12 without rotating the direction of the ferrule 8, and therefore the optical fiber connector 2 can be assembled without making a mistake in the direction of the polished surface 8h of the ferrule 8.

In the metal tube-coated 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.

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 the protective tube 15 can be easily inserted 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.

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 in a state where it can move axially 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 this 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.

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

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

Finally, the effects described in this disclosure are merely examples and are not intended to be limiting, and other effects may be achieved, or only 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.

REFERENCE SIGNS LIST 1 Metal tube covered optical cable 2 Optical fiber connector 3 Optical fiber core 4 Metal tube 5 Armored wire 7 Outer jacket 8 Ferrule 9 Ferrule holding portion 10 Stop ring 11 Spring 12 Plug frame 13 Crimping ring 14 Ring 15 Protective tube 15a Opening surface 15c Front end portion 16 Boot 17 Knob (housing)
100 Metal tube coated optical fiber cable with optical connector

Claims (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 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. 2. The metal-tube-covered optical fiber cable with optical connector according to claim 1, wherein the outer edge of the metal tube is inserted into the one end of the ferrule holding portion in the axial direction with a gap, so that the one end is not fixed to the metal tube. 3. The metal-tube-covered optical fiber cable with optical connector according to claim 1, wherein the connector portion is provided with a restricting member fixed to the outer periphery of the metal-tube-covered optical fiber cable and restricting movement of the ferrule toward the tip side of the connector portion. The connector portion is
a stop ring fixed to the outer periphery of the metal tube-covered optical fiber cable;
3. The metal tube-covered optical fiber cable with optical connector according to claim 1, further comprising: a plug frame fixed to the stop ring and configured to restrict movement of the ferrule toward the tip end of the connector portion. The ferrule has a flange portion protruding from an outer circumferential surface,
5. The metal tube-covered optical fiber cable with optical connector according to claim 4, wherein the plug frame comprises: an insertion hole for inserting the ferrule; and a support portion provided on a surface forming the insertion hole and abutting against the flange portion to restrict movement of the ferrule toward the tip side of the connector portion. 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 pipe without fixing the other end to the metal pipe;
and fixing the other axial end of the ferrule holding portion to the ferrule.