JPH11142684A - Structure and method for coupling optical fiber cord and ferrule - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coupling structure for an optical fiber and a ferrule which effectively prevents optical transmission loss from increasing and has superior operation efficiency. SOLUTION: A metallic ferrule has a core hold part 2 in which a coated optical fiber part 8 is fitted and a coating hold part 3 in which a coating part 7 is fitted. The coated optical fiber part 8 is fitted to the core hold part 2 of the ferrule 1 and the part having the coating part 7 is fitted to the coating hold part 3 of the ferrule 1; and the coated optical fiber part 8 is fused to a tapered peripheral surface 2b on the end part side of the core hold part 2 and caulked 3b at the position of the coating hold part 3. Then an adhesive is charged through an inside/outside penetrating adhesive hole 20 formed in the coating hold part 3 at a position closer to the core hold part 2 than the caulking 3b position.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical fiber cord / ferrule connection structure and an optical fiber cord / ferrule connection structure for connecting an optical fiber cord and a ferrule to each other.

[0002]

2. Description of the Related Art For example, when a plastic optical fiber cord is connected to a device or the like, a method is generally employed in which an optical connector attached to a terminal of the optical fiber cord is used.

[0003] When an optical connector is attached to the optical fiber cord, a metal ferrule is usually used in order to position the optical fiber cord and prevent axial misalignment.

As shown in FIG. 5, a ferrule 1 of this type is formed in a cylindrical shape, and has a core holding portion 2 having a core insertion hole into which an optical fiber core of an optical fiber cord is inserted. And a coating holding portion 3 having a coating insertion hole 3a into which the portion of the optical fiber cord having the coating portion is inserted. In addition, on the outer peripheral surface of the coating holding portion 3,
For positioning with the optical connector, there is provided a flange portion 4 which is formed to protrude radially outward.

[0005] Ferrule 1 is attached to the optical fiber cord.
6, the coating 7 at the end of the optical fiber cord 6 is stripped and removed by a predetermined length to expose the optical fiber core 8 as shown in FIG. 6 (coating stripping step). ). In the figure, reference numeral 9 denotes a Kevlar as a reinforcing member for reinforcing in the length direction, which is buried in the covering portion 7 in the length direction in the vicinity of the optical fiber core portion 8.

[0006] Next, as shown in FIG.
Is folded back to the covering portion 7 side (Kevlar folding step), and as shown in FIG. 8, in a state where a predetermined amount of the adhesive 11 is applied (adhesive applying step), a coating fitting hole is formed from the coating holding portion 3 side of the ferrule 1. 9, the optical fiber core portion 8 is inserted into the core insertion hole 2 a of the core holding portion 2 as a projecting shape, and the portion having the coating portion 7 is covered with the coating holding portion 3 as shown in FIG. 9. Is obtained (fitting step).

[0007] Then, as shown in FIG. 10, in the fitted state, a predetermined position of the cover holding section 3 is swaged from both sides by swaging 3 b.
As a result, a state in which the optical fiber cord 6 and the ferrule 1 are connected and fixed to each other is obtained (caulking step).
Here, the optical fiber cord 6 and the ferrule 1 are connected to each other by the adhesive 7, the Kevlar 9 and the adhesive strength between the optical fiber core 8 and the ferrule 1, and the covering 7 by the caulking 3b. The optical fiber cord 6 has a connection structure in which the optical fiber cord 6 is held in a retaining shape from the ferrule 1 by the sandwiching pressure of the coating holding section 3 against the Kevlar 9.

[0008] The caulking process is performed, for example, as shown in FIG.
As shown in FIG. 12, when the coating holding portion 3 of the ferrule 1 is positioned between the upper and lower pair of caulking jigs 13 and 14 and pressurized by the caulking jigs 13 and 14 in the up and down direction, as shown in FIG. The crimped state 3b of the holding part 3 is obtained. As shown in FIGS. 11 and 12, the optical fiber core portion 8 is composed of a central fiber core 8a and a cladding 8b covering the outer periphery thereof.

After the caulking process, as shown in FIG. 13, an optical fiber core portion 8 protruding from the core holding portion 2 is pressed against a hot plate mirror plate 16a of a hot plate main body 16 as a heating device. Fig. 9
10 is welded to the gradually expanding tapered peripheral surface 2b on the end side of the core wire insertion hole 2a of the core wire holding part 2 shown in FIG. 10 (welding step), and then, as shown in FIG. The end surface of the optical fiber core portion 8 is polished by, for example, and finished to a mirror surface state in which the end surface of the optical fiber core portion 8 is flush with the end surface of the ferrule 1 as shown in FIG. 15 (mirror finishing step).

[0010]

However, according to the conventional connection structure between the optical fiber cord 6 and the ferrule 1, if the ferrule 1 is left for a long time in a high temperature condition, the end face of the core holding portion 2 of the ferrule 1 will not move. As a result, the optical fiber cord 6 shrinks into a depressed state, which causes a problem that optical transmission loss increases.

On the other hand, the contraction rate of the optical fiber cord 6 can be reduced by increasing the amount of the adhesive 11, but if the amount of the adhesive 11 is increased, the adhesive 11 is moved from the tip of the ferrule 1. The adhesive 11 is likely to remain on the ferrule 1 end surface even after the welding or polishing, and the optical fiber core portion 8 and the adhesive 11 are mixed,
On the contrary, there is a disadvantage that the optical transmission loss increases.

Further, if welding or polishing is performed in a state where the adhesive 11 is not dried, the ferrule 1 is processed with the tip thereof facing downward, so that the adhesive 11 flows out from the tip of the ferrule 1 and optical transmission loss increases. There was also a disadvantage of doing so.

For this reason, it is necessary to adjust the amount of the adhesive 11 to an appropriate amount and to perform welding or polishing after the adhesive 11 is sufficiently dried and cured, resulting in a disadvantage that the working efficiency is extremely poor. there were.

On the other hand, there is a method of increasing the crimping force in order to increase the holding force of the optical fiber cord 6 and the ferrule 1 in a fixed state. 6 itself is compressed, and the optical transmission loss increases.

In view of the above problems, an object of the present invention is to provide a connection structure and a connection method between an optical fiber cord and a ferrule which effectively prevent an increase in optical transmission loss and have excellent work efficiency.

[0016]

The technical means of the connecting structure for achieving the above object is to provide an optical fiber cord having an end portion in an optical fiber cord provided with a coating portion covering an outer periphery of an optical fiber core portion. The stripped and removed optical fiber core portion is fitted into the core holding portion of the metal ferrule, and the portion having the coating portion is fitted into the coating holding portion of the metal ferrule, and the core holding portion is provided. The optical fiber core portion is welded to the inner peripheral surface side of the core holding portion on the end side of the optical fiber core, and the fitted optical fiber core portion and the coating portion are bonded to the metal ferrule with an adhesive, and the coating holding portion is provided. In the connection structure of the optical fiber cord and the ferrule which are connected and fixed to each other by being caulked at the part position, the covering holding part of the metal ferrule is located closer to the cord holding part side than the caulking position. , Lies in and out through like adhesive injection hole is formed.

Further, the adhesive injection hole may be formed in the vicinity of the core wire holding portion.

Further, the technical means of the connecting method for achieving the above object is to peel off the coating at the end of an optical fiber cord provided with a coating covering the outer periphery of the optical fiber core. After removing, the optical fiber core portion is fitted into the core holding portion of the metal ferrule, and the portion having the coating portion is fitted into the coating holding portion of the metal ferrule, and the optical fiber is held at the end side of the core holding portion. By welding the fiber core portion to the inner peripheral surface side of the core holding portion, bonding the fitted optical fiber core portion and the coating portion to the metal ferrule with an adhesive, and caulking at the coating holding portion position. In a method of connecting an optical fiber cord and a ferrule to be connected and fixed to each other, the core holding of a metal ferrule in which an inner or outer penetrating adhesive injection hole is formed in the coating holding portion located near the core holding portion. And a fitting step of fitting a portion having an optical fiber core portion and a covering portion to the covering holding portion, a caulking process of caulking the position of the covering holding portion after the fitting process, and a core holding portion after the caulking process. A welding step of welding the optical fiber core portion to the inner peripheral surface side of the optical fiber holding portion on the end side of the optical fiber, a mirror finishing step of processing the optical fiber core end portion into a mirror surface after the welding step, and the mirror finishing After the step, an adhesive injection step of injecting an adhesive from the adhesive injection hole.

[0019]

Embodiments of the present invention will be described below with reference to the drawings. The same components as those described above are denoted by the same reference numerals, and description thereof will be omitted.

As shown in FIGS. 1 to 4, the metal ferrule 1 is formed in a cylindrical shape as described above, and has a core wire insertion hole 2a into which the optical fiber core portion 8 of the optical fiber cord 6 is inserted. Core holder 2 and optical fiber cord 6
And a cover holding portion 3 having a cover fitting hole 3a into which a portion having the covering portion 7 is fitted. In addition, a flange portion 4 is formed on the outer peripheral surface of the coating holding portion 3 so as to project radially outward for positioning with the optical connector.

Further, the ferrule 1 in the present embodiment
The inside and outside of the adhesive holding hole 3 are formed in the covering holding portion 3 near the core wire holding portion 2.

As described above, the optical fiber cord 6 also has an optical fiber core 8, a coating 7 provided to cover the outer periphery of the optical fiber core 8, and a length embedded in the coating 7. The structure has a Kevlar 9 as a reinforcing body for directional reinforcement.

When the ferrule 1 is connected and fixed to the end of the optical fiber cord 6, the coating 7 at the end of the optical fiber cord 6 is stripped off by a predetermined length as shown in FIG. Then, the optical fiber core portion 8 is exposed (covering portion peeling step).

Next, as shown in FIG.
Is folded back to the coating portion 7 side (Kevlar folding step), and the ferrule 1 is applied without applying the adhesive 11 as in the related art.
From the coating holding portion 3 side through the coating insertion hole 3a,
As shown in FIG. 2, the optical fiber core portion 8 is inserted into the core wire insertion hole 2 a of the core wire holding portion 2 as a projecting shape, and the portion having the coating portion 7 is the coating insertion hole 3 a of the coating holding portion 3. Is obtained (fitting step).

Then, as shown in FIG. 3, by crimping 3b the predetermined position of the coating holding portion 3 from both sides in the fitted state, a state in which the optical fiber cord 6 and the ferrule 1 are connected and fixed to each other is obtained. (Caulking process). Here, the optical fiber cord 6 is retained in the ferrule 1 in a retaining shape.

Note that this caulking may be performed by a method similar to the conventional one, as shown in FIG.

After the caulking process, as shown in FIG. 13, the optical fiber core portion 8 protruding from the core holding portion 2 is pressed against the hot plate mirror plate 16a of the hot plate main body 16 as a heating device. And melted by heating to fuse the tapered peripheral surface 2b of the core wire holding portion 2 with the tapered peripheral surface 2b gradually expanding at the tip end side of the core wire insertion hole 2a (welding step).
As shown in FIG. 4, the end face of the optical fiber core portion 8 is polished with a polishing paper 17 or the like, and as shown in FIG. 4, the end surface of the optical fiber core portion 8 is finished to a mirror surface state flush with the ferrule 1 end surface. (Mirror finishing process).

Thereafter, the adhesive 11 is injected into the ferrule 1 through the adhesive injection hole 20 (adhesive injection step). In this case, the injected adhesive 11 permeates into the gap between the inner surface of the ferrule 1 and the outer surface of the optical fiber cord 6.

Here, the optical fiber cord 6 and the ferrule 1 are bonded to each other by the adhesive 7, the Kevlar 9 and the adhesive force between the optical fiber core 8 and the ferrule 1, and the coating by the caulking 3b. 7 and the Kevlar 9 by the clamping force of the coating holding part 3, the optical fiber cord 6
Is a connecting structure that is retained from the ferrule 1 in a retaining shape.

As described above, according to the connecting structure and the connecting method of the present embodiment, the optical fiber core 8 is formed on the tapered peripheral surface 2b on the distal end side of the core holding portion 2 of the ferrule 1.
On the other end side of the coating holding section 3, the inner peripheral surface of the coating holding section 3 and the outer peripheral surface of the coating section 7 are in close contact with each other as shown in FIG. When the adhesive 11 is injected from the adhesive injection hole 20,
The outflow of the adhesive 11 from the end of the ferrule 1 can be effectively prevented, and the injection amount of the adhesive 11 can be efficiently increased without causing the adhesive 11 to flow out. The adhesive 11 can be sufficiently filled also in the optical fiber core portion 8 and the coating portion 7, and the holding power of the optical fiber cord 6 in the ferrule 1 is improved. Even in this case, it is possible to effectively prevent the end face of the optical fiber core portion 8 on the tip face side of the ferrule 1 from contracting due to the contraction of the optical fiber cord 6, and effectively prevent an increase in optical transmission loss.

Further, due to the increase in the filling amount of the adhesive 11,
Since the holding force between the optical fiber cord 6 and the ferrule 1 is improved, the crimping 3b force can be set lower, and from this point, an increase in optical transmission loss can be effectively suppressed.

Further, in the production process, there is no need to wait for the adhesive 11 to dry and harden as in the related art, so that the working efficiency can be improved and the production time can be shortened.

Since the adhesive injection hole 20 is formed in the vicinity of the core wire holding portion 2, the adhesive 1 for the gap portion on both the core wire insertion hole 2a side and the cover insertion hole 3a side is formed.
There is also an advantage that the filling of 1 can be performed more efficiently.

The optical fiber cord 6 is not limited to the plastic optical fiber cord 6, but may be a glass (quartz) optical fiber cord 6 or the like.

[0035]

As described above, according to the connecting structure and the connecting method of the optical fiber cord and the ferrule of the present invention,
An inner and outer penetrating adhesive injection hole is formed in the sheath holding portion of the metal ferrule, closer to the core wire holding portion than the caulking position, and the core wire holding portion and the sheath holding portion of the metal ferrule are respectively provided. A fitting step of fitting the portion having the optical fiber core portion and the covering portion, and after the fitting step, a caulking process of caulking the coating holding portion position, and after the caulking process,
A welding step of welding the optical fiber core portion to the inner peripheral surface side of the optical fiber holding portion at the end portion side of the core holding portion, and a mirror finishing process of processing the optical fiber core end portion into a mirror surface after the welding process. After the mirror finishing step, an adhesive injecting step of injecting an adhesive from the adhesive injecting hole, wherein the optical fiber core portion is welded to the ferrule core tip portion side. The other end side of the coating holding portion is caulked to be in a tight contact state, and when the adhesive is injected from the adhesive injection hole, the adhesive can be effectively prevented from flowing out. Can be increased well,
Since the holding power of the optical fiber cord in the ferrule is improved, it is possible to effectively prevent the end face of the optical fiber core portion at the tip side of the ferrule due to contraction of the optical fiber cord, and to effectively prevent an increase in optical transmission loss. There is an advantage.

Further, since the holding force between the optical fiber cord and the ferrule is improved by increasing the filling amount of the adhesive,
The crimping force can be set lower, and from this point, there is an advantage that an increase in optical transmission loss can be effectively suppressed.

Furthermore, in the production process, there is no need to wait for the adhesive to dry and harden as in the conventional case, and there is an advantage that the working efficiency can be improved and the production time can be shortened.

Further, if the adhesive injection hole is formed near the core wire holding portion, there is an advantage that the adhesive can be filled more efficiently.

[Brief description of the drawings]

FIG. 1 is a perspective view of a ferrule according to an embodiment of the present invention.

FIG. 2 is a cross-sectional side view showing a connection process between an optical fiber cord and a ferrule.

FIG. 3 is a cross-sectional side view showing a connection process between an optical fiber cord and a ferrule.

FIG. 4 is a cross-sectional side view showing a connection process between an optical fiber cord and a ferrule.

FIG. 5 is a perspective view showing a conventional ferrule.

FIG. 6 is a side view showing a connection process between the optical fiber cord and the ferrule.

FIG. 7 is a side view showing a connection process between the optical fiber cord and the ferrule.

FIG. 8 is a side view showing a connection process between the optical fiber cord and the ferrule.

FIG. 9 is a cross-sectional side view showing a connection process between the optical fiber cord and the ferrule.

FIG. 10 is a sectional side view showing a connection process between the optical fiber cord and the ferrule.

FIG. 11 is a cross-sectional side view showing a connection process between the optical fiber cord and the ferrule.

FIG. 12 is a cross-sectional side view showing a connection process between the optical fiber cord and the ferrule.

FIG. 13 is a perspective view showing a connection process between an optical fiber cord and a ferrule.

FIG. 14 is a perspective view showing a connecting process between the optical fiber cord and the ferrule.

FIG. 15 is a sectional side view showing a connection process between the optical fiber cord and the ferrule.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Ferrule 2 Core holding part 2a Core insertion hole 2b Taper peripheral surface 3 Coating holding part 3a Coating insertion hole 3b Caulking 6 Optical fiber cord 7 Coating part 8 Optical fiber core part 11 Adhesive 16 Hot plate body 16a Hot plate mirror Face plate 17 Abrasive paper 20 Adhesive injection hole

Claims (3)

[Claims] 1. An optical fiber cord having a coating covering an outer periphery of a core of an optical fiber, wherein the coating at an end of the optical fiber is stripped and removed to form a core of a metal ferrule. While being fitted into the wire holding portion, the portion having the coating portion is fitted into the coating holding portion of the metal ferrule, and the optical fiber core portion at the end side of the core holding portion is on the inner peripheral surface side of the core holding portion. At the same time, the optical fiber cord and the ferrule are connected and fixed to each other by being welded, and the fitted optical fiber core portion and the coating portion and the metal ferrule are bonded by an adhesive, and caulked at the coating holding portion position. In the connection structure, the coating holding portion of the metal ferrule is formed with an inner and outer penetrating adhesive injection hole located closer to the cord holding portion side than the caulking position. Coupling structure between Aibakodo and the ferrule. 2. The apparatus according to claim 1, wherein the adhesive injection hole is formed near the core wire holding portion.
Connection structure between the described optical fiber cord and ferrule. 3. An optical fiber cord provided with a coating covering an outer periphery of an optical fiber core portion, wherein said coating portion at an end portion of the optical fiber cord is peeled off and the optical fiber core portion is made of a metal ferrule core. While fitting into the holding portion, the portion having the coating portion is fitted into the coating holding portion of the metal ferrule, and the optical fiber core portion is welded to the inner peripheral surface side of the core holding portion at the end side of the core holding portion. Along with, the fitted optical fiber core portion and the covering portion and the metal ferrule are bonded with an adhesive,
In the method of connecting an optical fiber cord and a ferrule, which are connected and fixed to each other by caulking at the position of the sheath holding portion, an inside / outside penetrating adhesive injection hole is formed in the sheath holding portion located near the core wire holding portion. A core holding portion and a coating holding portion of a metal ferrule, a fitting step of fitting a portion having an optical fiber core portion and a coating portion, respectively, after the fitting step, a crimping step of crimping the coating holding portion position, After the caulking step, a welding step of welding the optical fiber core portion to the inner peripheral surface side of the core holding portion on the end side of the core holding portion, and after the welding step, processing the end face of the optical fiber core portion into a mirror-like shape. Connecting the optical fiber cord and the ferrule, comprising: a mirror finishing step of performing an adhesive injection step of injecting an adhesive from the adhesive injection hole after the mirror finishing step. Law.