Patent Application
20240369781
The present invention relates to an optical fiber cable with an optical connector, a method for manufacturing an optical fiber cable with an optical connector, and an optical connector.
Methods for attaching optical connectors to optical fiber cables are conventionally known. One of such methods includes interposing a tension member that is contained in an optical fiber cable, between a cylindrical part of an optical connector plug and a crimping ring (swaging ring) of an optical connector, and fixing it by crimping.
In one example, Japanese Patent No. 5281959 discloses an optical fiber code with an optical connector, which is assembled by fitting a stop ring and a plug frame of an optical connector to form a cylindrical part, interposing a tension member between the stop ring and a swaging ring, and swaging (crimping) the stop ring and the swaging ring.
Normally, standard optical connectors are designed to be attached to optical fiber cables having outer diameters of not greater than 3 mm, but there is a demand to attach a standard optical connector to an optical fiber cable having a relatively large outer diameter. For example, it may be desired to attach a standard LC connector to an optical fiber cable having an outer diameter of 4 to 6 mm, which is often used outdoors. There are basically two methods for attaching a standard optical connector to an optical fiber cable having a relatively large outer diameter.
In the first method, a dedicated optical connector plug is prepared by enlarging a cylindrical part of the optical connector plug so as to have a size close to an inner diameter of a crimping ring that has a relatively large diameter in accordance with an optical fiber cable. This first method, however, increases cost due to the need for the dedicated optical connector plug.
In the second method, an inner surface of a part on an optical connector plug side of a crimping ring is reduced in diameter so as to correspond to a cylindrical part of a standard optical connector plug. This crimping ring is reduced in diameter on a leading end side so as to correspond to a cylindrical part of a standard optical connector plug while having a size corresponding to a large diameter of an optical fiber cable, on a trailing end side. Thus, the second method uses a dedicated component having two different diameters, as a crimping ring.
Moreover, the total length of an optical connector is increased. Specifically, in order to fix an optical fiber to a ferrule by bonding and to draw out a tension member of an optical fiber cable to a cylindrical part of an optical connector plug, a space is required between the cylindrical part and a crimping ring. In addition, crimping the crimping ring to the cylindrical part requires that a large diameter part of the crimping ring has a length that allows the crimping ring to slide to a leading end side in an axial direction relative to the optical fiber cable. Furthermore, the axial length of a small diameter part of the crimping ring should be not less than the width of a crimping tool. For these reasons, a crimping ring that is long in the axial direction is required, resulting in an increase in the total length of an optical connector.
In view of these circumstances, an object of the present invention is to enable attaching an optical fiber cable having a relatively large outer diameter to a standard size optical connector plug, without increasing the total length of an optical connector.
A first aspect of the present invention is an optical fiber cable with an optical connector, comprising:
A second aspect of the present invention is a method for manufacturing an optical fiber cable with an optical connector, comprising:
A third aspect of the present invention is an optical connector being configured to be attached to an optical fiber cable, the optical connector comprising:
One embodiment of the present invention enables attaching an optical fiber cable having a relatively large outer diameter to a standard size optical connector plug, without increasing the total length of an optical connector.
Hereinafter, an optical connector and an optical fiber cable with an optical connector according to one embodiment of the present invention will be described with reference to the attached drawings.
As shown in
As shown in
The optical fiber 11 includes a core and a clad on an outer side of the core and is structured such that a refractive index of the core is made higher than that of the clad in order to transmit light to the core at the center. Preferably, both of the core and the clad are made of quartz glass or plastic that has a high light transmittance.
The core wire 12 is disposed around the optical fiber 11 to protect it. Any material can be used for the core wire 12, but for example, silicon resin, nylon resin, elastomer, or UV-curable resin can be used.
The tension member 13 is provided so as to prevent the optical fiber 11 from being damaged, by alleviating tension that is generated in the optical fiber 11 covered with the core wire 12, when the optical fiber cable 1 is pulled or bent, for example. Although the material of the tension member 13 is not limited, examples of the material include aramid fibers, such as Kevlar (registered trademark), aramid fiber-reinforced plastics (AFRP), glass fibers, glass fiber-reinforced plastics (GFRP), polyethylene fibers, and polyethylene fiber-reinforced plastics.
The outer jacket 14 is disposed on an outer side of the tension member 13 so as to protect the optical fiber 11, which is covered with the core wire 12, and to protect the tension member 13. Any material can be used for the outer jacket 14, but for example, polyvinyl chloride resin or elastomer can be used. The outer diameter of the outer jacket 14 is greater than a cylindrical part 31 of the optical connector plug 3 and is 4 to 6 mm, for example.
With reference to
The optical connector plug 3 is a connector plug corresponding to an LC connector in the example shown in
In this disclosure, each constituent component will be described by assuming that a side on which the ferrule 33 protrudes as shown in
The crimping ring 5 is an example of a crimping member for fixing the optical fiber cable 1 to the optical connector plug 3 by crimping (swaging), and it has a cylindrical shape. As shown in
The outer circumferential surface of the crimping ring 5 is formed with an engaging groove 53 for preventing the boot 6 from coming off.
The inner diameter of the crimping ring 5 is set in accordance with the outer diameter of the outer jacket 14 of the optical fiber cable 1 and thereby greatly differs from the outer diameter of the cylindrical part 31 of the optical connector plug 3. For this reason, the optical connector 2 of one embodiment includes the cylinder member 4 that is interposed between the cylindrical part 31 of the optical connector plug 3 and the crimping ring 5.
The cylinder member 4 is attached to the cylindrical part 31 in such a manner that an inner circumferential surface is in contact with an outer circumferential surface of the cylindrical part 31. The outer circumferential surface of the cylinder member 4 is set slightly smaller than the inner diameter of the crimping ring 5. Specifically, the cylinder member 4 is disposed so as to absorb the difference between the inner diameter of the crimping ring 5 and the outer diameter of the cylindrical part 31.
In order to contain the tension member 13, which is exposed from the optical fiber cable 1, between the outer circumferential surface of the cylinder member 4 and the inner circumferential surface of the crimping ring 5, the outer diameter of the cylinder member 4 is preferably smaller than the inner diameter of the crimping ring 5 by the thickness of the tension member 13. The difference between the outer diameter of the cylinder member 4 and the inner diameter of the crimping ring 5 is preferably not less than 0.1 mm and not greater than 1 mm and is more preferably not less than 0.1 mm and not greater than 0.5 mm.
The cylinder member 4 can be attached to the cylindrical part 31 by any method, but preferably by crimping. Specifically, as described later, the cylinder member 4 is temporarily fixed to the cylindrical part 31 by crimping. The attaching method is, however, not limited thereto, and the cylinder member 4 may be attached to the cylindrical part 31 by press fitting.
In
The boot 6 is provided to cover the crimping ring 5 and a part of the optical fiber cable 1 in order to protect the crimped parts of the crimping ring 5 and the optical fiber cable 1 from foreign substances, water drops, etc.
The optical connector plug 3 has a resin plug housing 35 for containing the ferrule 33, the coil spring 34, and the tube 36. The plug housing 35 is composed of a first housing part 35A and a second housing part 35B. The first housing part 35A and the second housing part 35B are coupled by snap-fit, for example. The cylindrical part 31 is fixed to the second housing part 35B. The second housing part 35B is made by insert molding that uses a metal pipe corresponding to the cylindrical part 31 as an insert component.
In a case of using an LC connector, the ferrule 33 has a ferrule main body 333 at a leading end, and the ferrule main body 333 has an outer diameter of 1.249 mm and is formed with a through hole for allowing the optical fiber 11 of the optical fiber cable 1 to pass through.
The optical fiber 11 is fixed by inserting it into the through hole in which adhesive is already injected, and then heating them. The adhesive is, for example, thermosetting adhesive, and it is preferably epoxy adhesive or acrylic adhesive.
The coil spring 34 is supported at a leading end by a flange part 332 of the ferrule 33 and is also supported at a trailing end by a surface (not shown) of the second housing part 35B, whereby it biases the ferrule 33 to the leading end side.
The tube 36 is formed of flexible resin, such as polytetrafluoroethylene (PTFE), and it is attached to a trailing end part 331 of the ferrule 33. The tube 36 is provided in order to extend the flange part 332 of the ferrule 33 to the cylindrical part 31.
Next, cross sections of the cylindrical part 31 of the optical connector plug 3, the cylinder member 4, and the crimping ring 5 and a method for fixing them will be described with reference to
In
In
Although the types of the crimping tools in crimping the cylinder member 4 and in crimping the crimping ring 5 are not limited, tools for holding a part to be crimped, from each side, are used. There is no limitation in the shape of a crimping hole that is formed in a crimping tool when it holds a part to be crimped, but for example, the shape is circular or is preferably polygonal, such as hexagonal.
In a case in which a crimping hole has a polygonal shape, the inner circumferential surface 52 of the crimping ring 5 is crimped to the outer circumferential surface 41 of the cylinder member 4 at a plurality of positions at equal intervals in the circumferential direction. This further increases a holding force against torque that is applied in a rotation direction of the optical fiber cable 1.
In one embodiment, the cylinder member 4 is formed with a protrusion 43 (an example of a first protrusion) that protrudes outward from the outer circumferential surface 41 approximately at the center in the axial direction, as shown in
Providing the protrusion 43 to the cylinder member 4 also contributes to an improvement in a crimping force of the crimping ring 5 relative to the cylinder member 4. Specifically, in crimping the outer circumferential surface 51 of the crimping ring 5, the crimping ring 5 is firmly fixed to the cylinder member 4 due to the protrusion 43 formed to the cylinder member 4. At this time, the inner circumferential surface 312 of the cylindrical part 31 is further bent inward at the position corresponding to the protrusion 43 and is deformed to cause a decrease in the outer diameter.
Due to crimping the crimping ring 5, the tension member 13 is strongly supported between the surface of the protrusion 43 and the inner circumferential surface 52 of the crimping ring 5. This further increases a pull-out force of the optical fiber cable 1 from the optical connector plug 3.
The protrusion 43 of the cylinder member 4 shown in
In
In
In
For the purpose of increasing the crimping force, it is also effective to provide a second protrusion that protrudes inward from the inner circumferential surface, to the cylinder member, instead of or in addition to the first protrusion that protrudes outward from the outer circumferential surface.
In
The protrusion 44D increases stress for the outer circumferential surface 311 of the cylindrical part 31, when the cylinder member 4D is crimped (temporarily fixed) to the cylindrical part 31 of the optical connector plug 3. This improves the crimping force between the cylindrical part 31 and the cylinder member 4D. In this temporary fixation, the inner circumferential surface 312 of the cylindrical part 31 is slightly bent inward at a position corresponding to the protrusion 44D. In crimping the outer circumferential surface 51 of the crimping ring 5, due to the protrusion 44D formed to the cylinder member 4D, the inner circumferential surface 312 of the cylindrical part 31 is further bent inward at the position corresponding to the protrusion 44D, and the crimping ring 5, the cylinder member 4D, and the cylindrical part 31 are firmly fixed together. At this time, the tension member 13 is strongly supported between the outer circumferential surface of the cylinder member 4D and the inner circumferential surface 52 of the crimping ring 5.
In
In
In
Next, a method for manufacturing the optical fiber cable with the optical connector of one embodiment will be described with reference to
With reference to
In step ST2, the outer jacket 14 of the optical fiber cable 1 is removed to expose the core wire 12, which covers the optical fiber 11, and to expose the tension member 13, which is disposed around the core wire 12. At this time, exposure is performed stepwise so as to form a part from which only the outer jacket 14 is removed, and a part from which the outer jacket 14 and the tension member 13 are removed. The length from a leading end of the outer jacket 14 to a leading end of the core wire 12 (length of the core wire 12 that is exposed) is in a range of not less than 10 mm and not greater than 50 mm. The length of the tension member 13 exposed from the outer jacket 14 is in a range of not less than 5 mm and not greater than 20 mm. However, these lengths are not limited thereto.
In step ST3, the cylinder member 4 is attached to the cylindrical part 31 in such a manner that the inner circumferential surface of the cylinder member 4 is in contact with the outer circumferential surface of the cylindrical part 31, which is provided to the optical connector plug 3. The cylinder member 4 is preferably formed with a protrusion on one or each of the outer circumferential surface and the inner circumferential surface, as described with reference to
With reference to
In step ST5, the exposed optical fiber 11 is fixed to the ferrule 33 of the optical fiber cable 1 by bonding. Specifically, thermosetting adhesive is injected into the through hole of the ferrule 33 from a dispenser (syringe) containing the thermosetting adhesive, via the trailing end of the cylindrical part 31 and the tube 36 (refer to
In step ST6, the inner circumferential surface of the cylinder member 4 is at least partially crimped (temporarily fixed) to at least a part of the outer circumferential surface of the cylindrical part 31 of the optical connector plug 3. The cylinder member 4 is temporarily fixed to the cylindrical part 31 in order to prevent the cylinder member 4 from coming off or deviating in the axial direction from the cylindrical part 31 during a working process.
Nevertheless, it is not essential to temporarily fix the cylinder member 4 to the cylindrical part 31 by crimping. In one example, the cylinder member 4 may be press-fitted to the cylindrical part 31 of the optical connector plug 3 in step ST3 so as to not come off or deviate in the axial direction from the cylindrical part 31. Then, step ST6 is not required.
In step ST7, the crimping ring 5 is slid in the axial direction and is disposed around the cylinder member 4. In this case, a trailing end of the second housing part 35B (refer to
In step ST8, the inner circumferential surface of the crimping ring 5 is at least partially crimped to at least a part of the outer circumferential surface of the cylinder member 4 while having the tension member 13 of the optical fiber cable 1 therebetween, at the first position P1 in the axial direction (an example of a first crimping step). Moreover, in step ST8, the inner circumferential surface of the crimping ring 5 is also at least partially crimped to the outer jacket 14 of the optical fiber cable 1, at the second position P2 in the axial direction (an example of a second crimping step). The cylindrical part 31 of the optical connector plug 3, the cylinder member 4, and the crimping ring 5 are firmly fixed together in step ST8.
Crimping the crimping ring 5 at the first position P1 and crimping the crimping ring 5 at the second position P2 may be performed simultaneously in a case in which an axial distance between the first position P1 and the second position P2 is not greater than the width of a crimping tool (e.g., not greater than 10 mm). This reduces a workload of steps compared with the case of performing the crimping operation twice by sliding a crimping tool.
In step ST9, the boot 6 is slid in the axial direction to be engaged with the crimping ring 5. Specifically, a protrusion (not shown) on an inner circumferential surface of the boot 6 is engaged with the engaging groove 53 of the crimping ring 5, whereby the boot 6 is positioned in the axial direction.
After the above-described steps are performed, the optical fiber cable with the optical connector shown in
As described above, the optical fiber cable with the optical connector of one embodiment is provided with the cylinder member 4 that is interposed between the cylindrical part 31 of the optical connector plug 3 and the crimping ring 5. The cylinder member 4 is attached to the cylindrical part 31 in such a manner that the inner circumferential surface 42 of the cylinder member 4 is in contact with the outer circumferential surface 311 of the cylindrical part 31. In the crimping ring 5, the inner circumferential surface 52 is at least partially crimped to at least a part of the outer circumferential surface 41 of the cylinder member 4 while having the tension member 13 of the optical fiber cable 1 therebetween, at the first position in the axial direction. In addition, the inner circumferential surface 52 is also at least partially crimped to the outer jacket 14 of the optical fiber cable 1, at the second position in the axial direction. That is, in attaching the optical fiber cable 1 having a relatively large outer diameter, to the optical connector plug 3, the cylinder member 4 is disposed so as to absorb the difference between the inner diameter of the crimping ring 5 and the outer diameter of the cylindrical part 31. Thus, it is possible to reduce the total length of the optical connector. In this state, the cylindrical part 31, the cylinder member 4, and the crimping ring 5 are firmly fixed together by crimping.
In one embodiment, the cylinder member 4 is provided with one or both of the first protrusion, which protrudes outward from the outer circumferential surface, and the second protrusion, which protrudes inward from the inner circumferential surface. This structure further increases the crimping force of the cylinder member 4 relative to the cylindrical part 31 and the crimping force of the crimping ring 5 relative to the cylinder member 4.
In one embodiment, a crimping tool having a hole with a polygonal shape, such as a hexagonal shape, is used to perform crimping (e.g., hexagonal swaging) on a part to be crimped, whereby a holding force against rotational torque that is generated in the optical fiber cable 1, is further increased.
Although embodiments of the optical fiber cable with the optical connector, the method for manufacturing the optical fiber cable with the optical connector, and the optical connector of the present invention are described above, the present invention should not be limited to the foregoing embodiments. In addition, various modifications and changes can be made to the above-described embodiments within the scope not departing from the gist of the present invention.
For example, although a case of using an LC connector is described in relation to the foregoing embodiments, the present invention can also be used in an SC connector, an MU connector, and other connectors. The type of the connector is not limited thereto, and the present invention can also be used in optical connectors having similar structures.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2022-057954 | Mar 2022 | JP | national |
This application is a National Stage Entry application of PCT International Application No. PCT/JP2023/012749, filed on Mar. 29, 2023, which claims the priority benefit of Japanese Patent Application No. 2022-057954, filed on Mar. 31, 2022, the entire contents of both of which are hereby incorporated by reference.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2023/012749 | 3/29/2023 | WO |
