JP2001013373A - Protective cap - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a protective cap which protects the end face of a ferule and that of an optical fiber and which makes the condition of these end faces visible, with the protective cap fitted to an optical fiber connector, at the time of the assembly of the optical fiber connector and the optical fiber or thereafter. SOLUTION: This is a protective cap 20 for an optical fiber connector assembly, which is equipped with a ferule 11 for retaining an inserted optical fiber and with a member 15 for holding the ferule 11; the protective cap is provided with the shape that fits to the holding member 15 and that covers at least the ferule 11, is formed with a transparent or translucent resin that makes the inside visible, and is designed to have at least one convex lens 26, 27 at the position oppositely facing the end face of the ferule 11 and at the position oppositely facing the periphery of the end face of the ferule 11.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention protects the ferrule end face and the optical fiber end face of an optical fiber connector and visually recognizes the state of the ferrule end face and the optical fiber end face in a state where a protective cap is fitted to the optical fiber connector. To a protective cap that can be used.

[0002]

2. Description of the Related Art Conventionally, when an optical fiber is fixed to a ferrule to be assembled to an optical fiber connector, a thermosetting adhesive is injected into the optical fiber connector, and then an optical fiber having a predetermined coating removed is inserted. The adhesive is heated and cured by a heater, and the optical fiber is bonded and fixed to the optical fiber connector. The optical fiber connector is used after the optical fiber is bonded and fixed, and the end face of the ferrule and the end face of the optical fiber are polished smoothly and finished to a mirror surface. If the polished ferrule and the polished surface of the optical fiber are damaged, when the ferrules are connected to each other, the precision of the facing position is deteriorated and the loss is increased. Therefore, in order to protect the ferrule end face and the optical fiber end face after polishing, a rubber fitting to the tip of the optical fiber connector,
2. Description of the Related Art A protective cap formed of plastic or the like is known.

[0003]

However, since this conventional protective cap is used only after the end faces of the ferrule and the optical fiber are polished, an adhesive is injected into the optical fiber connector to insert the optical fiber. At times and until the ferrule end face and the optical fiber end face are polished, the ferrule end face and the optical fiber end face are not protected and are easily exposed and damaged, and there is a problem in safety during operation.

Accordingly, the present invention has been made in view of such circumstances,
At the time of assembling the optical fiber connector and the optical fiber, or even thereafter, the ferrule end surface and the optical fiber end surface are protected, and the state of the ferrule end surface and the optical fiber end surface is changed with the protective cap fitted to the optical fiber connector. It is an object to provide a protective cap that can be visually recognized.

[0005]

According to a first aspect of the present invention, there is provided a ferrule for inserting and holding an optical fiber, and a protective cap for an optical fiber connector assembly including a holding member for holding the ferrule. Wherein the ferrule has a shape fitted to the holding member and covers at least the ferrule, and is formed of a transparent or translucent resin whose inside can be visually recognized, and a position facing the end face of the ferrule and a position of the ferrule. A protective cap having at least one convex lens at a position opposed to a peripheral portion of an end face.

According to a second aspect of the present invention, in the first aspect, the convex lens is provided continuously in a circumferential direction at a position opposed to a peripheral portion of an end face of the ferrule. In the protective cap. Third of the present invention
The aspect of the present invention is the protective cap according to the first or second aspect, wherein the protective cap is formed of a heat-resistant resin whose inside can be visually recognized.

According to a fourth aspect of the present invention, in any one of the first to third aspects, the optical fiber connector assembly comprises:
The protective cap is characterized in that the ferrule, a spring for urging the ferrule in the axial direction, and a stop ring having a through hole into which a rear end of the ferrule is inserted are pre-assembled. The fifth of the present invention
In the aspect, in any one of the first to third aspects, the optical fiber connector assembly is an assembly for any one of FC type, SC type, and ST type optical fiber connectors. In the protective cap.

According to a sixth aspect of the present invention, in any one of the first to fifth aspects, a rear end portion of the protective cap is provided with a first insertion hole fitted with the holding member, and the first insertion hole. A second insertion hole communicating with the hole and being smaller than the first insertion hole; and when the holding member is inserted up to a locking portion due to a step between the first insertion hole and the second insertion hole. And a protective cap having a sufficient gap between the bottom of the second insertion hole and the ferrule.

According to a seventh aspect of the present invention, in any one of the first to sixth aspects, at least the thickness of the resin fitted into the optical fiber connector assembly is formed to be substantially uniform. A protective cap is characterized in that:
An eighth aspect of the present invention is the protective cap according to any one of the first to sixth aspects, wherein the protective cap has a Fresnel lens instead of the convex lens.

In the protective cap of the present invention, the ferrule end face and the optical fiber end face are more reliably protected, and the state of the ferrule end face and the optical fiber end face can be visually recognized with the protective cap fitted to the optical fiber connector.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an example of an embodiment of the present invention will be described in detail with reference to the drawings. (Embodiment 1) FIG. 1 is a plan view of a protective cap according to Embodiment 1 of the present invention, FIG. 2 is a sectional view of a protective cap and a basic plug of a universal type optical fiber connector, and FIG. 3 is an optical fiber using the protective cap. FIG. 4 shows an explanatory view of a connector assembling method.

First, a universal type optical fiber connector will be described. As shown in FIG. 2, in the basic plug 10 of the universal type optical fiber connector according to the present embodiment, a ferrule 11 to which an optical fiber is fixed includes a ferrule cylindrical body 12 having an optical fiber insertion hole 12a, and a ferrule cylindrical body. And a flange member 13 fixed to the rear end of the body 12. A compression spring 14 is mounted on the outer peripheral portion of the flange member 13 of the ferrule 11, and a stop ring 15 is fitted outside the compression spring 14 so as to cover the compression spring 14. That is, the compression spring 14 urges and holds the ferrule 11 forward with respect to the stop ring 15.
1 can be retracted by a predetermined amount. The basic plug 10 is fitted into a plug housing (not shown),
It becomes an optical fiber connector.

As shown in FIGS. 1 and 2, the protective cap 20 according to the first embodiment is formed in a cylindrical shape having a small outer diameter at the front end and a basic plug at the rear end. 10 has an inner diameter on the rear end side to fit into the stop ring 15 of the basic plug 10 and at least a stop ring from the distal end of the flange member 13 of the ferrule 11. A large-diameter insertion hole 21 longer than the distal end portion 15 is formed. Also,
A small-diameter insertion hole 22 having an inner diameter that fits into the ferrule cylindrical body 12 of the basic plug and longer than the ferrule cylindrical body 12 is formed following the large-diameter insertion hole 21. In addition, a step 23 formed by a difference in inner diameter is provided between the large-diameter insertion hole 21 and the small-diameter insertion hole 22.

The thickness of the protective cap 20 is substantially uniform over the large-diameter insertion hole 21 and the small-diameter insertion hole 22, and the large-diameter cylindrical portion 24 and the small-diameter cylindrical portion 25 are formed respectively. When fitted to the distal end of the basic plug 10, the small diameter opposite to the bottom surface of the small diameter cylindrical portion 25 facing the end face of the ferrule cylindrical body 12 of the small diameter cylindrical portion 25 and the peripheral portion of the end surface of the ferrule cylindrical body 12. Convex lenses 26 and 27 are formed integrally with the side surface of the cylindrical portion 25, respectively. The convex lenses 26 and 27 are provided such that the focal point is near the opening of the optical fiber insertion hole 12a of the ferrule cylindrical body 12. The convex lenses 26 and 27 may be integrally formed, may be formed by polishing after molding, or may be formed by bonding a separately molded convex lens, and is not particularly limited. An arbitrary number of ribs 28 are formed on the outer periphery of the small-diameter cylindrical portion 25 on the large-diameter cylindrical portion 24 side, and a disc-shaped flange 29 is formed on the rear end side of the large-diameter cylindrical portion 24. I have.

As a material of the protective cap 20, a transparent material whose inside can be visually recognized, for example, an acrylic resin or a styrene resin can be used. A procedure for assembling an optical fiber connector using the protective cap 20 according to the present embodiment will be described. First, when the protection cap 20 is fitted to the tip of the basic plug 10, the protection cap 2
The step portion 23 of 0 is locked to the flange member 13 of the ferrule 11.

Next, as shown in FIG. 3A, the adhesive injector 30 is inserted from the base end side of the adhesive injection jig 40,
Insert the tip of the adhesive injection jig 40 into the basic plug 1
0 at the rear end. Thereafter, as shown in FIG. 3B, the thermosetting adhesive 50 is injected into the optical fiber insertion hole 12a of the ferrule 11, and the ferrule 11 is filled with the thermosetting adhesive 50. The filling of the heat-curable adhesive 50 can be confirmed by visually confirming that the heat-curable adhesive 50a has come out from the tip of the optical fiber insertion hole 12a of the ferrule 11. Particularly in the present embodiment, the convex lenses 26 and 2
7, the distal end of the optical fiber insertion hole 12a is enlarged, so that it can be more easily confirmed. After the filling of the heat-curable adhesive 50 has been completed, FIG.
As shown in (d), the adhesive injector 30 and the adhesive injection jig 40 are removed from the basic plug 10.

Next, as shown in FIG. 3E, the optical fiber 60 from which a predetermined coating has been removed is inserted into the rear end of the basic plug 10. Also at this time, the protrusion of the distal end portion 60a of the optical fiber 60 from the distal end portion of the optical fiber insertion hole 12a of the ferrule 11 can be easily visually recognized by the convex lenses 26 and 27, so that the optical fiber 60 can be reliably inserted.

Thereafter, the protective cap 20 is removed from the distal end of the basic plug 10, and the thermosetting adhesive 50 is cured by externally heating with a heater (not shown), and the optical fiber 60 and the basic plug 10 are bonded. Let it. Thereafter, the protection cap 20 is fitted to the tip of the basic plug 10 again to protect the ferrule end face and the tip of the optical fiber.

Further, even after the ferrule end face and the optical fiber end face are polished smoothly and mirror-finished, the protective cap 20 is again fitted to the tip of the basic plug 10 to protect the ferrule end face and the optical fiber end face. Can be. Therefore, according to the present embodiment, the ferrule end face and the optical fiber end face are more reliably protected, and the protective cap is used when assembling the optical fiber to the optical fiber connector. At times, the end face of the ferrule is enlarged by the convex lens of the protective cap, so that the working efficiency and the assembly accuracy at the time of assembly are improved. Further, after the optical fiber is assembled to the optical fiber connector, whether the ferrule end face and the optical fiber end face are before or after polishing can be easily recognized without removing the protective cap.

(Other Embodiments) In the first embodiment described above, the material of the protective cap 20 is formed of a transparent resin whose inside is visible and has no heat resistance. However, the material is not limited to this. As a material for the protective cap, a transparent material having heat resistance and visible inside, for example, polycarbonate, polyethylene terephthalate, polysulfone,
It may be formed of epoxy resin or polyetherimide.

The procedure for assembling the optical fiber connector using the protective cap is the same as that of the first embodiment up to the step of injecting the thermosetting adhesive and inserting the optical fiber. When cured by heating,
This is performed with the protective cap fitted, and the optical fiber and the basic plug are bonded. As described above, the protective cap is made of a transparent material having heat resistance, so that the end face of the ferrule and the end face of the optical fiber are more reliably protected, and the safety is high during the assembling work of the optical fiber connector and thereafter. Further, the thermal efficiency at the time of heating is increased by the protective cap, and the reliability and workability of bonding and fixing the optical fiber and the optical fiber connector are improved.

The shape and the like of the convex lens of the protective cap are not limited to the first embodiment. FIG. 4 is a plan view of a protective cap according to another embodiment, and FIG. 5 is a sectional view of a protective cap and a basic plug of a universal type optical fiber connector. Note that members having the same functions as those described in the above-described embodiment are denoted by the same reference numerals, and redundant description will be omitted.

In addition to the convex lens 26, the protective cap 20A has a convex lens 27A on the side surface of the small-diameter cylindrical portion 25 facing the peripheral edge of the end surface of the ferrule cylindrical body 12 along the circumferential direction.
Are integrally formed. The convex lens 27A is provided so that the focal point is near the opening of the optical fiber insertion hole 12a of the ferrule cylindrical body 12. As described above, since the convex lens 27A is formed along the circumferential direction of the small-diameter cylindrical portion 25, the protective cap 20A
The state of the end face of the ferrule cylindrical body 12 can be easily confirmed from any position in the circumferential direction of 0A.

Further, the above-described embodiment of the present invention has been described by taking the universal type optical fiber connector as an example, but it is needless to say that the present invention is not limited to this and can be applied to other optical fiber connectors. Below, SC type,
Description will be made by taking an example of an FC type or ST type optical fiber connector. FIG. 6 shows a partial cross-sectional view of a protective cap and an SC-type optical fiber connector according to another embodiment. Note that members having the same functions as those described in the above-described embodiment are denoted by the same reference numerals, and redundant description will be omitted.

The SC type optical fiber connector 70 includes a ferrule 11 and a bias holding member, all of which are plug housings 71.
This is an optical fiber connector for inserting and holding an optical fiber after assembling. Therefore, in the above-described embodiment, the large-diameter insertion hole 21 of the protection cap 20 is
However, in this embodiment, the large-diameter insertion hole 21B of the protective cap 20B is fitted into the plug housing 71, and the step 23B is engaged with the tip of the plug housing 71.

The method of assembling the optical fiber connector is as follows.
The steps of fitting B, injecting the adhesive, inserting the optical fiber, and heating and curing the adhesive are the same as those in the above-described embodiment. FIG. 7A shows a protective cap 20C for the FC optical fiber connector 80. The large-diameter insertion hole 21C of the protection cap 20C fits into the plug frame 81 of the FC-type optical fiber connector 80, and the step 23C engages with the tip of the plug frame 81.

FIG. 7B shows a protective cap 20D for the ST type optical fiber connector 90. The large-diameter insertion hole 21D of the protective cap 20D fits into the ST plug housing 91 of the ST-type optical fiber connector 90, and the step 23D engages the tip of the ST plug housing 91. As described above, by forming the protective cap so as to be fitted to the distal end portions of various optical fiber connectors, the same effects as those of the first embodiment can be obtained.

The convex lens of the present invention has convex surfaces on both sides,
The inside or outside of the cap may be convex, and the surface opposite to the convex may be a flat surface or a concave surface having a larger radius of curvature than the convex surface. Furthermore, it is also possible to make the cap surface substantially flat by using a Fresnel lens to make the entire wall thickness uniform.

[0029]

As described above, when the protective cap according to the present invention is used, the ferrule end face and the optical fiber end face can be protected while the optical fiber connector and the optical fiber are being assembled or later. The state of the end face of the ferrule and the end face of the optical fiber can be visually recognized in a state where the protective cap is fitted to the ferrule. Further, by forming the protective cap with a heat-resistant resin, the heat efficiency at the time of heat-curing the thermosetting adhesive is increased, and the reliability and workability of bonding and fixing the optical fiber and the optical fiber connector are improved.

[Brief description of the drawings]

FIG. 1 is a plan view of a protective cap according to Embodiment 1 of the present invention.

FIG. 2 is a sectional view of a protective cap and a basic plug of a universal optical fiber connector according to Embodiment 1 of the present invention.

FIG. 3 is an explanatory diagram of a method of assembling an optical fiber connector using a protective cap.

FIG. 4 is a plan view of a protective cap according to another embodiment of the present invention.

FIG. 5 is a cross-sectional view of a protective cap and a basic plug of a universal optical fiber connector according to another embodiment of the present invention.

FIG. 6 is a partial cross-sectional view of a protective cap and an SC-type optical fiber connector according to another embodiment of the present invention.

FIG. 7A is a partial cross-sectional view of a protective cap and an FC-type optical fiber connector according to another embodiment,
(B) is a partial cross-sectional view of a protective cap and an ST-type optical fiber connector according to another embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Basic plug 20, 20A, 20B, 20C, 20D Protective cap 26, 27, 27A Convex lens 30 Adhesive injector 40 Adhesive injecting jig 50, 50A Heat curing adhesive 60 Optical fiber 70 SC type optical fiber connector 80 FC Type optical fiber connector 90 ST type optical fiber connector

Continued on the front page (72) Inventor Junji Taira 1-8-8 Nakase, Mihama-ku, Chiba-shi, Chiba Seiko Instruments Inc. (72) Inventor Takeshi Uchiyama 1-8-1, Nakase, Mihama-ku, Chiba-shi, Chiba Seiko Instruments Inc. In-house F-term (reference) 2H036 QA23 QA24 QA34

Claims (7)

[Claims] 1. A protective cap for an optical fiber connector assembly comprising a ferrule for inserting and holding an optical fiber and a holding member for holding the ferrule, the protection cap being fitted to the holding member and covering at least the ferrule. Having at least one convex lens at a position facing the end face of the ferrule and a position facing the peripheral edge of the end face of the ferrule, the transparent or translucent resin having an inside visible. Features a protective cap. 2. The protective cap according to claim 1, wherein the convex lens is provided continuously in a circumferential direction at a position opposed to a peripheral portion of an end face of the ferrule. 3. The protective cap according to claim 1, wherein the protective cap is formed of a heat-resistant resin whose inside can be visually recognized. 4. The optical fiber connector assembly according to claim 1, wherein the optical fiber connector assembly includes a ferrule, a spring for urging the ferrule in an axial direction, and a rear end of the ferrule. A protective cap characterized by being preassembled with a stop ring having a through hole. 5. The optical fiber connector assembly according to claim 1, wherein the optical fiber connector assembly is an FC type, SC type, or ST type optical fiber connector assembly. Protective cap. 6. The protective cap according to claim 1, wherein a rear end side of the protective cap is fitted with the holding member.
An insertion hole, a second insertion hole communicating with the first insertion hole and being smaller than the first insertion hole, up to a locking portion due to a step between the first insertion hole and the second insertion hole; A protective cap, wherein when the holding member is inserted, there is a sufficient gap between the bottom of the second insertion hole and the ferrule. 7. The protective cap according to claim 1, wherein at least the thickness of the resin fitted into the optical fiber connector assembly is formed to be substantially uniform.