HK1169488B - Method for connecting optical fibers - Google Patents

Description

Optical fiber connection method

Technical Field

The present invention relates to an optical fiber connecting method for mechanically connecting two optical fibers.

Background

Japanese laid-open patent publication No.2000-121863 discloses the following mechanical splice and a coated optical fiber connection part using the same: the mechanical splice is used for abutting the end surfaces of two bare fibers and connecting the bare fibers. Recently, various types of optical fibers having different coating diameters (optical fiber diameters) have been used. Therefore, in the technique disclosed in japanese laid-open patent publication No.2000-121863, it is necessary to separately prepare mechanical splices as optical fiber connectors for optical fibers of various diameters.

Disclosure of Invention

< problems to be solved by the present invention >

The present invention aims to provide a simple method as follows: the same fiber optic connector is used to mechanically join optical fibers regardless of the diameter of the optical fibers.

< means for solving the problems >

To achieve the above object, there is provided an optical fiber connecting method for mechanically connecting two optical fibers using an optical fiber connector including a mechanical splice for connecting a first optical fiber having a coating diameter D, the two optical fibers including a second optical fiber having a coating diameter D smaller than the coating diameter D. The optical fiber connection method comprises the following steps: a first step of inserting said second optical fiber into a ferrule to obtain a jacketed optical fiber; secondly, fixing the sleeved optical fiber in an optical fiber holder; a third step of inserting the jacketed optical fiber fixed in the fiber holder into the mechanical splice and abutting the ends of the two optical fibers including the jacketed optical fiber; and a fourth step of fixing the jacketed optical fiber to the mechanical splice in a state where the distal ends of the two optical fibers including the jacketed optical fiber are in contact with each other.

The mechanical joint may include: a base having a fiber groove for positioning the optical fiber; a pressing member for pressing the optical fiber on the base, the optical fiber being disposed in the optical fiber groove; and a clamping member for holding the base and the pressing member together. In the first embodiment of the present invention, a ferrule for holding an embedded optical fiber is fixed in the base portion, and in the third step, the jacketed optical fiber fixed in the fiber holder is inserted into the mechanical splice, and the ends of the jacketed optical fiber and the embedded optical fiber are brought into abutment. In the second embodiment of the present invention, in the second step, two fiber holders are prepared, and two of the jacketed optical fibers are fixed in the corresponding one of the two fiber holders. In the third step, the two jacketed optical fibers fixed in the two fiber holders are inserted into the mechanical splice from both sides thereof, and the distal ends of the jacketed optical fibers are abutted.

The bushing is preferably a bushing as follows: at least one end of the sleeve is shaped such that the diameter of the end increases towards one end. In addition, the bushing is preferably a bushing as follows: at least one end face of the ferrule is inclined with respect to a plane perpendicular to the axis of the ferrule.

Drawings

Fig. 1 is a perspective view showing an optical fiber connector used in a first embodiment of the present invention;

FIG. 2 is a cross-sectional view of an optical fiber showing a mechanical splice included in the fiber optic connector of FIG. 1;

fig. 3A, 3B, and 3C are cross-sectional views perpendicular to the optical fiber of the mechanical splice included in the optical fiber connector of fig. 1, and show the calking before insertion, during insertion, and after extraction, respectively.

FIG. 4 is a schematic view showing a first embodiment of an optical fiber connecting method of the present invention, and is a perspective view showing a state in which a small-diameter optical fiber is set on a fiber holder for a large-diameter optical fiber;

fig. 5 is a schematic view showing a first embodiment of an optical fiber connecting method of the present invention, and is a perspective view showing a state where a small-diameter optical fiber is inserted into an optical fiber connector for a large-diameter optical fiber;

FIG. 6 is a cross-sectional view corresponding to FIG. 5;

fig. 7 is a schematic view showing a first embodiment of an optical fiber connecting method of the present invention, and is a perspective view showing a state after a small-diameter optical fiber is inserted into an optical fiber connector for a large-diameter optical fiber;

FIG. 8 is a cross-sectional view corresponding to FIG. 7;

fig. 9 is a schematic view showing a first embodiment of an optical fiber connecting method of the present invention, and is a perspective view showing a state after the calking portion is pulled out from the optical fiber connector;

fig. 10A and 10B are sectional views showing an example of a ferrule used for the optical fiber connecting method of the present invention; and

fig. 11 is a sectional view showing a mechanical splice of an optical fiber connector used in the second embodiment of the optical fiber connecting method of the present invention.

Detailed Description

An embodiment of an optical fiber connecting method according to the present invention will be described with reference to the accompanying drawings.

In the drawings, the same or equivalent parts are denoted by the same reference numerals and their description is not repeated.

Fig. 1 is a perspective view showing an optical fiber connector 1 used in a first embodiment of an optical fiber connecting method of the present invention. The optical fiber connector 1 is a mechanical splice type connector in which an optical fiber having a coating diameter (optical fiber diameter) D (0.9mm in this case) is disposed. The optical fiber connector 1 is provided with: a mechanical splice 2 for mechanically connecting optical fibers; a housing 3 for accommodating the mechanical joint 2; and a grip 4 for covering the front end to the middle of the housing 3. A spring (not shown) that urges the mechanical joint 2 forward is provided in the housing 3.

Fig. 2 is a cross-sectional view of the optical fiber including the mechanical splice 2. Fig. 3A, 3B, and 3C are cross-sectional views perpendicular to the optical fiber of the mechanical splice 2, respectively showing states before insertion of the calking portion, during insertion of the calking portion, and after extraction of the calking portion. The mechanical joint 2 has a substrate (base) 7, and the substrate 7 has: a V-shaped fiber groove 6 for positioning the optical fiber 5; a pressing plate (pressing member) 8 for pressing the optical fiber 5 disposed in the fiber groove 6 against the base 7; and a U-shaped snap spring (clamping member) 9 for holding the base 7 and the pressing member 8 together.

A ferrule 11 holding a short-length embedded (embedded) optical fiber 10 is integrally fixed to the distal end portion of the base 7. The front end face of the ferrule 11 is polished. The embedded fiber 10 extends from the front end face of the ferrule 11 into the fiber groove 6 of the mechanical splice 2.

A plurality of (in this case, two) caulking-part insertion cavities 12 are formed in the mechanical joint 2 at the boundary between the base 7 and the pressing member 8, and the caulking part 32a of the caulking member 32 (fig. 5 and 6) is inserted into the plurality of caulking-part insertion cavities 12. The clamping member 9 clamps the base 7 and the pressing member 8 together from the side opposite to the caulking portion insertion cavity 12.

A plurality of (two in this case) elongated through holes 13 (fig. 1) are formed in the housing 3, and the calk portion 32a is inserted into the calk portion insertion chamber 12 through the elongated through holes 13. An elongated through hole 14a and a cutout 14b are formed in the grip 4 at positions corresponding to the elongated through hole 13.

In the optical fiber connector 1, when the optical fiber 5 is to be connected to the built-in optical fiber 10, the calking portion 32a is first inserted into the calking portion insertion cavity 12 of the mechanical splice 2 via the elongated through hole 14a and the slit 14B of the grip 4 and the elongated through hole 13 (fig. 3B) of the housing 3. Thereby placing the base portion 7 and the pressing member 8 of the mechanical joint 2 in the open state.

Then, the optical fiber 5 is inserted into the mechanical splice 2 from the side (rear) of the mechanical splice 2 opposite to the ferrule 11, and the distal end face of the optical fiber 5 is placed against the distal end face of the embedded optical fiber 10 (fig. 2). In this state, the caulking portion 32a is pulled out from the caulking portion insertion cavity 12 of the mechanical joint 2 (fig. 3C). Then, the clamping member 9 closes the base 7 and the pressing member 8, and the optical fiber 5 and the built-in optical fiber 10 are fixed together in the mechanical splice 2 in a state of being connected to each other.

Next, a method for connecting an optical fiber having a coating diameter (optical fiber diameter) D (0.25 mm in this case) smaller than the diameter D to the built-in optical fiber 10 provided in the mechanical splice type connector (optical fiber connector) 1 will be described as a first embodiment of the optical fiber connecting method of the present invention. In this specification, an optical fiber having an optical fiber diameter D is referred to as a small diameter optical fiber, and an optical fiber having an optical fiber diameter D larger than the optical fiber diameter D is referred to as a large diameter optical fiber.

Fig. 4 is a schematic view showing a first embodiment of the optical fiber connecting method of the present invention, and is a perspective view showing a state in which a small-diameter optical fiber is set on the fiber holder 15 for a large-diameter optical fiber. The fiber holder 15 has a holder base 16 and a holder guide 17, and the holder guide 17 is provided to be movable forward and backward with respect to the holder base 16. The holder base 16 has a top face portion convexly curved upward. A fiber groove 18 for positioning the optical fiber is formed in the top surface portion.

Attached at the rear of the holder base 16 is a generally U-shaped rear fiber securing cover 19, which rear fiber securing cover 19 is used to secure the optical fiber in the fiber groove 18. The optical fiber fixing cover 19 can be opened and closed by means of a shaft (not shown) provided on the holder base 16. Rubber is preferably fixed to the back surface of the rear optical fiber fixing cover 19. A bite receiving hole 20 is formed at the distal end portion of the rear optical fiber fixing cap 19. Snap-receiving hole 20 snaps with snap projections 21 provided on the side of holder base 16, thereby restraining the optical fiber provided in fiber groove 18 against the rear of holder base 16.

Attached in front of the rear fiber securing cover 19 in the holder base 16 is a generally U-shaped intermediate fiber securing cover 22, which intermediate fiber securing cover 22 is used to secure the fiber in the fiber groove 18. The intermediate fiber securing cover 22 can be opened and closed by means of a shaft (not shown) provided on the gripper base 16. A bite receiving hole 23 is formed at the distal end portion of the intermediate optical fiber fixing cap 22. The snap-receiving hole 23 snaps with a snap projection 24 provided on the side of the holder base 16, thereby restraining the optical fiber provided in the optical fiber groove 18 against the middle of the holder base 16.

A fiber support portion 25 is provided at the front end of the gripper guide 17. A fiber groove 26 for positioning the optical fiber is formed in the top surface portion of the fiber support portion 25. A front fiber pressing cover 27 for pressing the optical fiber in the fiber groove 26 is integrally fixed on the fiber supporting portion 25, and the front fiber pressing cover 27 can be opened and closed by means of a pivot. A snap projection 28 is provided on the rear surface of the front optical fiber pressing cap 27. The optical fiber in the optical fiber groove 26 can be prevented from being lifted upward by causing the snap projection 28 to snap into the snap receiving hole 29 formed in the top surface portion of the optical fiber support portion 25.

When a small-diameter optical fiber 5 (the optical fiber diameter is 0.25mm) is to be connected to a built-in optical fiber 10 provided in an optical fiber connector 1, the small-diameter optical fiber 5 is first inserted into a ferrule 30 (the inner diameter of the ferrule 30 is 0.3mm to 0.5mm, slightly larger than the optical fiber diameter of the small-diameter optical fiber) having an outer diameter substantially the same as the optical fiber diameter D (0.9mm) of the large-diameter optical fiber, thereby obtaining a jacketed optical fiber (ferrule) 31. The sleeve 30 is formed of resin or the like, and the outer diameter of the sleeve 30 is preferably D ± 0.1 mm.

The jacketed optical fiber 31 is then held in the fiber holder 15. Specifically, the jacketed optical fiber 31 is placed in the fiber groove 18 of the holder base 16 and the fiber groove 26 of the holder guide 17 in a state where the rear fiber securing cover 19, the intermediate fiber securing cover 22, and the front fiber pressing cover 27 are opened. The rear fiber securing flap 19, the intermediate fiber securing flap 22 and the front fiber press flap 27 are then closed. Thus, the rear fiber securing cover 19 and the intermediate fiber securing cover 22 secure the jacketed optical fiber 31 in the holder base 16, and the front fiber pressing cover 27 presses the distal end portion of the jacketed optical fiber 31. At this time, the rear fiber securing cap 19 and the intermediate fiber securing cap 22 press the small-diameter optical fiber 5 of the jacketed optical fiber 31 together with the ferrule 30. Fixing rubber to the back of the rear fiber securing cover 19 enables the jacketed optical fiber 31 to be more securely fixed to the holder base 16.

Fig. 5 is a perspective view showing a state where a small-diameter optical fiber is inserted into the optical fiber connector 1 for a large-diameter optical fiber. Fig. 6 is a sectional view corresponding to fig. 5. Further, the caulking member 32 and the assembly auxiliary jig 33 are prepared. The caulking portion 32a is inserted into the caulking portion insertion cavity 12 of the mechanical joint 2, thereby creating a state in which the base portion 7 and the pressing member 8 of the mechanical joint 2 are opened. In this state, the optical fiber connector 1 is placed in the connector receiving part 34 of the assembly auxiliary jig 33 so that the caulking member 32 is located at the top.

Then, the fiber holder 15 holding the jacketed optical fiber 31 is set on the side opposite to the optical fiber connector 1 on the assembly auxiliary jig 33. Then, the fiber holder 15 is moved toward the optical fiber connector 1 on the assembly auxiliary jig 33. After the jacketed optical fiber 31 held in the fiber holder 15 is inserted into the optical fiber connector 1, the intermediate fiber securing cover 22 is opened. In this state, the fiber holder 15 is further moved toward the optical fiber connector 1. Then, the jacketed optical fiber 31 inserted into the mechanical splice 2 is made to collide with the internal optical fiber 10.

Fig. 7 is a perspective view showing a state after a small-diameter optical fiber is inserted into the optical fiber connector 1 for a large-diameter optical fiber. Fig. 8 is a sectional view corresponding to fig. 7. When the distal end of the jacketed optical fiber 31 collides with the distal end of the built-in fiber 10, the jacketed optical fiber 31 is tilted upward relative to the fiber holder 15 between the front fiber pressing cover 27 and the rear fiber fixing cover 19 of the fiber holder 15, and the above-described collision state is maintained by the restoring force of the jacketed optical fiber 31.

Fig. 9 is a perspective view showing a state after the calking portion is pulled out from the optical fiber connector. The base portion 7 and the pressing member 8 of the mechanical joint 2 are closed by pulling out the caulking portion 32a from the caulking portion insertion cavity 12 of the mechanical joint 2. Thereby, the embedded optical fiber 10 and the jacketed optical fiber 31 are fixed in the mechanical splice 2 in a connected state. Thus, the small-diameter optical fiber can be easily connected to the built-in optical fiber held in the ferrule using the optical fiber connector having the mechanical splice for the large-diameter optical fiber. Then, the front fiber pressing cover 27 and the rear fiber securing cover 19 of the fiber holder 15 are opened, and the optical fiber connector 1 assembled with the jacketed optical fiber 31 is removed from the assembly auxiliary jig 33.

Fig. 10A and 10B are sectional views showing an example of a ferrule used in the optical fiber connecting method of the present invention. To facilitate the insertion of the small-diameter optical fiber 5 into the ferrule 30, one end portion of the ferrule 30 is preferably formed in a flare shape gradually increasing in diameter toward one end, as shown in the example of fig. 10A. One end face of the sleeve 30 may also be cut at an angle with respect to a plane perpendicular to the axis of the sleeve 30, as shown in the example of fig. 10B. In both cases, the opening area of at least one end face of the ferrule 30 is increased, and therefore the small-diameter optical fiber 5 can be easily inserted into the ferrule 30 from the opening of the end portion.

Therefore, the optical fiber connector 1 having the mechanical splice 2 for the large-diameter optical fiber can be used for both the small-diameter optical fiber and the large-diameter optical fiber. There is no need to separately prepare an optical fiber connector having a mechanical splice for a small-diameter optical fiber. Significant advantages in cost are obtained since there is no need to design and manufacture the internal structure of the mechanical splice with a complex shape to accommodate both small and large diameter optical fibers.

Since the ferrule 30 of the jacketed optical fiber 31 and the small-diameter optical fiber 5 are integrally fixed by the rear fiber fixing cap 19 of the fiber holder 15 and the jacketed optical fiber 31 is inserted into the mechanical splice 2 in this state, the small-diameter optical fiber 5 does not move out of alignment with the ferrule 30 when the jacketed optical fiber 31 and the internal optical fiber 10 are set in abutment. Therefore, the jacketed optical fiber 31 and the internal optical fiber 10 are caused to collide with each other with sufficient force, thereby reliably connecting the small-diameter optical fiber 5 and the internal optical fiber 10.

Fig. 11 is a sectional view showing a mechanical splice 40 of an optical fiber connector used in the second embodiment of the optical fiber connecting method of the present invention. Like the mechanical splice 2 (fig. 2 and 3), the mechanical splice 40 is composed of a base 7, a pressing member 8, and a clamping member 9, the base 7 having a fiber groove 6. A plurality of caulking portion insertion cavities 12 are provided at the boundary between the base 7 and the pressing member 8. The fiber groove 6 of the mechanical splice 40 is sized for connecting two impinging large diameter optical fibers having a coating diameter D. The mechanical joint 40 is covered by a housing (not shown in the drawings).

When two small-diameter optical fibers 5 having a coating diameter D smaller than the coating diameter D are to be connected using an optical fiber connector having a mechanical splice 40, the two small-diameter optical fibers 5 are first inserted into a ferrule 30 having an outer diameter D so as to obtain a jacketed optical fiber 31. Then, two fiber holders 15 are prepared, and the jacketed optical fiber 31 is held/fixed in each fiber holder 15.

Then, the two jacketed optical fibers 31 are inserted into the mechanical splice 40 from both sides of the mechanical splice 40 in a state where the base 7 and the pressing member 8 of the mechanical splice 40 are opened by the caulking member 32, so that the ends of the jacketed optical fibers 31 collide with each other. In this state, the caulking member 32 is removed from the mechanical joint 40, and the base 7 and the pressing member 8 of the mechanical joint 40 are closed. Thus, the jacketed optical fiber 31 is fixed in the mechanical joint 40 in a state of being connected to each other, and two small-diameter optical fibers can be easily connected to each other with an optical fiber connector having a mechanical joint for a large-diameter optical fiber.

In the second embodiment, two small-diameter optical fibers 5 are connected, but the following embodiments are also possible: wherein a small diameter optical fiber 5 having a coating diameter D and a large diameter optical fiber having a coating diameter D are mechanically spliced. In the present embodiment, only the small-diameter optical fiber 5 is inserted into the ferrule 30 so as to obtain the jacketed optical fiber 31 having the outer diameter D to be fixed in the mechanical splice later, and the large-diameter optical fiber is fixed in the mechanical splice without change.

As described above, when an optical fiber connector having a mechanical splice for a large-diameter optical fiber is used for mechanically connecting an optical fiber including a small-diameter optical fiber in the optical fiber connecting method of the present invention, the small-diameter optical fiber is first inserted into a ferrule so as to obtain a jacketed optical fiber. Then, the jacketed optical fiber is inserted into the mechanical splice, the ends of the two optical fibers including the jacketed optical fiber are set in abutment, and the jacketed optical fiber is fixed in the mechanical splice in this state. By manufacturing the jacketed optical fiber in this manner, even when an optical fiber connector having a mechanical splice for a large-diameter optical fiber is used, it is possible to easily mechanically connect optical fibers that will include small-diameter optical fibers.

The invention is not limited to the embodiments described. For example, the diameter of the optical fiber used is not limited to the value described in the embodiments. The size and structure of the mechanical joint are not limited to those of the above-described embodiments.

< Industrial Applicability >

The fiber optic connection method of the present invention may be used to connect optical fibers to subscribers in an optical interconnect of a building.

Claims (5)

1. An optical fiber connection method for mechanically connecting two optical fibers using an optical fiber connector, the optical fiber connector comprising a mechanical splice designed for connecting a first optical fiber having a coating diameter D; the two optical fibers include a second optical fiber having a coating diameter D that is less than the coating diameter D; and the optical fiber connecting method includes:

a first step of inserting the second optical fiber into a ferrule formed of a resin having an outer diameter identical to a coating diameter D of the first optical fiber to obtain a jacketed optical fiber;

a second step of fixing the jacketed optical fiber in the fiber holder in such a manner that a second optical fiber of the jacketed optical fiber is pressed together with the ferrule by a fixing cover of the fiber holder;

a third step of inserting the jacketed optical fiber fixed in the fiber holder into the mechanical splice and abutting the ends of the two optical fibers including the jacketed optical fiber; and

and a fourth step of integrally fixing the ferrule of the jacketed optical fiber and the second optical fiber to the mechanical splice in a state where the distal ends of the two optical fibers including the jacketed optical fiber are in contact with each other.

2. The optical fiber connecting method according to claim 1,

the mechanical joint includes: a base having a fiber groove for positioning the jacketed optical fiber; a pressing member for pressing the jacketed optical fiber on the base, the jacketed optical fiber being disposed in the optical fiber groove; and a clamping member for holding the base and the pressing member together,

a ferrule for holding a built-in optical fiber is fixed to the base; and is

In the third step, the jacketed optical fiber fixed in the fiber holder is inserted into the mechanical splice, and the ends of the jacketed optical fiber and the embedded optical fiber are brought into abutment.

3. The optical fiber connecting method according to claim 1,

the mechanical joint includes: a base having a fiber groove for positioning the jacketed optical fiber; a pressing member for pressing the jacketed optical fiber on the base, the jacketed optical fiber being disposed in the optical fiber groove; and a clamping member for holding the base and the pressing member together,

in the second step, two fiber holders are prepared, and two jacketed optical fibers are held in a corresponding one of the two fiber holders; and is

In the third step, the two jacketed optical fibers fixed in the two fiber holders are inserted into the mechanical splice from both sides thereof, and the distal ends of the jacketed optical fibers are abutted.

4. The optical fiber connection method according to any one of claims 1 to 3,

the following sleeves were used as the sleeves: at least one end of the sleeve is shaped such that the diameter of the end increases towards one end.

5. The optical fiber connection method according to any one of claims 1 to 3,

the following sleeves were used as the sleeves: at least one end face of the ferrule is inclined with respect to a plane perpendicular to the axis of the ferrule.