JPH11109179A - Ferrule for optical fiber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a ferrule for optical fiber in which a plastic optical fiber is prevented from being protruded from the end surface. SOLUTION: In an optical fiber ferrule having a coated fiber holding hole 21 for holding and housing a plastic optical fiber, a fixing space part S (hole 12, 12') for arresting the axial movement of the plastic optical fiber is provided at the tip of the coated fiber holding hole 21. According to this structure, a coated fiber protruded from the coated fiber holding hole 21 can be filled and fixed to the fixing space part S by fusing softening.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a ferrule for a plastic optical fiber.

[0002]

2. Description of the Related Art Japanese Unexamined Patent Publication (Kokai) No. 58-187903 discloses a ferrule for a plastic optical fiber as shown in FIG. That is, the ferrule 30 has a through hole 30c through which the optical fiber penetrates on the central axis, and the cutout portion 3 having an inclined shape centered on the central axis is formed on the distal end surface 30a.
0b is provided. Reference numeral 30d denotes an inclined portion for facilitating insertion of the optical fiber into the through hole 30c.

When an optical fiber is fixed to a ferrule, the optical fiber is inserted from the inclined surface 30d at the rear end of the ferrule 30 to pass through the through hole 30c. With the tip of the optical fiber slightly protruding from the end face 30a, the protruding portion and the end face 30a of the ferrule 30 are heated by a heating body such as a hot plate. When the tip of the optical fiber is pressed in the direction of the end face 30a while being heated, the optical fiber is melted and softened, becomes diametrically enormous, is filled in the cutout portion 30b, and the optical fiber is fixed to the ferrule 30.

[0004]

As described above, in the conventional ferrule, a notch is provided on the opening end face of the through hole, and the optical fiber protruding from the end face is melted and softened by a heating body to fill the notch. The optical fiber was fixed to the ferrule. Therefore, the optical fiber does not move inward from the ferrule end face.

However, in the conventional ferrule, the fusion between the optical fiber melted and softened during long-term use and the cut-off portion 30b of the ferrule due to the difference in the coefficient of thermal expansion of the optical fiber, sheath material, ferrule and the like. And the optical fiber jumps out from the end face 30a.
SUMMARY OF THE INVENTION It is an object of the present invention to provide a ferrule for a plastic optical fiber having a structure in which an optical fiber does not move inward from an end face of a ferrule and never projects outside.

[0006]

According to a first aspect of the present invention, there is provided an optical fiber ferrule having a core wire holding hole for holding a plastic optical fiber. A fixed space for preventing the plastic optical fiber from moving in the axial direction is provided at the distal end. According to the second aspect of the present invention, the fixed space portion is formed in a narrow shape at a central portion when viewed in the axial direction of the optical fiber. According to the third aspect of the present invention, the constricted shape of the fixed space portion is formed in a drum shape by an inverted trapezoidal cross section on the distal end side and a trapezoidal cross section on the inner side.

[0007] Since a fixed space portion such as a drum shape whose center portion is narrowly narrowed is provided at the distal end portion of the core wire holding hole penetrating the optical fiber of the ferrule, the melt-softened optical fiber is fixed in a drum shape or the like. The optical fiber is fixed by the constricted shape in the center of the fixed space portion even if the welding is separated due to the difference in the thermal expansion coefficient of each component, so that the optical fiber does not protrude from the end face. Of course, it does not move inward.

[0010] In the invention according to claim 4, the ferrule for an optical fiber comprises: an inner cylindrical body provided with the core wire holding hole;
An outer cylinder having a tapered portion provided at a tip end thereof, wherein the inner cylinder is inserted into the outer cylinder to form the fixed space. Since the inner cylindrical body having the core wire holding hole is inserted into the outer cylindrical body having a tapered portion at the tip end to provide a fixed space portion, a fixed space portion such as a drum-shaped fixed space having a narrow central portion is provided. Can be easily configured.

Further, in the invention of claim 5, a thread groove is provided for engaging the peripheral surface of the inner cylinder with the outer cylinder in contact with the outer cylinder, and the inner cylinder is screwed and fixed to the outer cylinder. It is characterized by doing so. Since the screw grooves (male screw, female screw) are provided on the peripheral surface where the inner cylinder and the outer cylinder are in contact with each other, the inner cylinder can be easily fixed to the outer cylinder.

[0010]

FIG. 1 shows an example of an embodiment of the present invention.
This will be described with reference to FIG. 1A and 1B show an embodiment of a ferrule according to the present invention, wherein FIG. 1A is a perspective view of an outer cylinder and an inner cylinder in a separated state, and FIG. 1B is a perspective view of a combination of the two. FIG. 2 is a cross-sectional view of the above-described combined state. As shown in FIGS. 1 and 2, the ferrule A is an outer cylinder 10.
And an inner cylindrical body 20 inserted therein. The inner cylindrical body 20 accommodates and protects the plastic optical fiber 1.

The outer cylindrical body 10 has a tapered portion 11 at the tip end.
A hole 12 having an inverted trapezoidal section with a wide outside and a narrow inside is provided at the tip of the tapered portion 11. A female screw 14 is provided on the inner peripheral surface 13 of the outer cylinder 10, and a flange 16 is provided on the rear open end 15.

On the other hand, a small-diameter core wire holding hole 21 for penetrating and holding a core wire 2 of the optical fiber 1 described later is provided on the center axis of the front half of the inner cylindrical body 20, and is connected to the core wire holding hole 21. A sheath holding hole 22 for housing and holding the sheath 3 of the optical fiber 1 is provided in the latter half. Also, the inner cylinder 20
A male screw 23 corresponding to the female screw 13 of the outer cylinder 10 is provided on the outer circumference of the outer cylinder 10, and an insertion restricting flange 24 is provided at the rear end of the outer circumference. The length can be regulated.

The ferrule A includes an inner cylinder 20 and an outer cylinder 10
Is inserted by turning the male screw 23 and the female screw 14 into engagement, and the flange 16 and the insertion regulating flange 24 are fixed in contact with each other. In this manner, the inner cylinder 20 is
In the state fixed in the inside, a hole 12 ′ having a trapezoidal cross section is formed at the distal end of the ferrule A by the inner surface 11 a of the tapered portion 11 of the outer cylindrical body 10 and the distal end surface 20 a of the inner cylindrical body 20.
Are formed, and together with the inverted trapezoidal hole 12 on the outside, constitute a fixing space S for fixing the optical fiber. That is, the fixed space S is formed in a drum shape with a narrow center at the center by the front and rear holes 12, 12 '.

In the above configuration, insertion of the optical fiber 1 into the ferrule A is performed as follows. First, FIG.
As shown in (A), the sheath 3 for protecting the core 2 made of plastic optical fiber is removed, and the core 2 is passed through the core holding hole 21 of the inner cylinder 20 as shown in FIG. At the same time, the sheath 3 is inserted into the sheath holding hole 22. Next, the outer cylindrical body 10 is covered from the front end side of the inner cylindrical body 20, and the female screw 14 and the male screw 23 are engaged by rotating the outer cylindrical body 10,
The inner cylindrical body 20 is housed in the outer cylindrical body 10 without twisting or flawing the optical fiber 1, particularly the core wire 2.

With the optical fiber 1 inserted into the ferrule A, when the core 2 projecting from the tip of the ferrule A, that is, the tip of the outer cylinder 10 is pressed by a hot plate (for example, a chrome-plated iron plate) (not shown), the core 2 protrudes. The portion melts and softens and becomes voluminous in the diameter direction of the shaft, and as shown in FIG. 3 (C), is filled in the fixed space S and the optical fiber 1 is fixed. When the space S is filled, the optical fiber 1 moves even if a force acts in either the forward or backward direction in the axial direction due to the constricted structure of the inverted trapezoidal and trapezoidal holes 12 and 12 ′ as described above. You will not be able to do it.

In the above embodiment, the space S
Was described as a constricted shape by two front and rear holes 12, 12 ', but as shown in FIG.
The above trapezoidal hole 12 is omitted, and the trapezoidal hole 1 inside is omitted.
The same effect can be obtained by using only the fixed space portion S 'of 2'. The fixed space S ′ is formed by melting and softening the core wire 2.
Is in the filled state, the inner wall 11a of the tapered portion 11 and the distal end surface 20a of the inner cylindrical body 20 are prevented from moving back and forth.

[0017]

As described above, according to the present invention, the following effects can be obtained. Since a fixed space portion such as a drum-shaped tapered center portion is provided at the distal end portion of the core wire holding hole that penetrates the optical fiber of the ferrule, the melt-softened optical fiber is filled and fixed in the fixed space portion. Even if the welding is separated due to the difference in the thermal expansion of the components, the optical fiber is fixed in the fixed space where the center is narrow and narrow, and it does not jump out from the end face nor move inward. 3). Since the inner cylindrical body having the core wire holding hole is inserted into the outer cylindrical body having a tapered portion at the distal end to provide a fixed space portion, a fixed space portion such as a drum-shaped fixed space portion having a narrow central portion is provided. Can be easily configured (claim 4). In addition, since the threaded grooves are provided on the peripheral surfaces of the inner cylinder and the outer cylinder that are in contact with each other, the inner cylinder and the outer cylinder can be easily fixed. .

[Brief description of the drawings]

FIG. 1 shows an embodiment of a ferrule according to the present invention,
(A) is a perspective view of the separated state of the outer cylinder and the inner cylinder, and (B) is a perspective view of the combined state.

FIG. 2 is a longitudinal sectional view of FIG.

3A and 3B are explanatory diagrams of an optical fiber insertion process to the ferrule of FIG. 1, wherein (A) shows a state before insertion of an optical fiber, (B) shows a state after insertion, and (C) shows a state after fusion of an optical fiber. FIG.

FIG. 4 is a sectional view of another embodiment of the present invention.

FIG. 5 is a configuration diagram of a conventional example.

[Explanation of symbols]

 Reference Signs List A ferrule 1 plastic optical fiber 2 core wire 3 sheath 10 outer cylinder 12 inverted trapezoidal hole 12 'trapezoidal hole 14 female screw 20 inner cylinder 21 core wire holding hole 22 sheath holding hole 23 male screw S, S' fixed space

Claims (5)

[Claims] 1. An optical fiber ferrule having a core wire holding hole for holding and housing a plastic optical fiber,
A ferrule for an optical fiber, wherein a fixed space for preventing the plastic optical fiber from moving in the axial direction is provided at a tip portion of the core wire holding hole. 2. The ferrule for an optical fiber according to claim 1, wherein said fixed space portion is formed in a shape in which a central portion is narrow and narrow when viewed in an axial direction of the optical fiber. 3. The ferrule for an optical fiber according to claim 2, wherein the constricted shape of the fixed space portion has an inverted trapezoidal cross section on the tip side and a trapezoidal cross section on the inner side. 4. An optical fiber ferrule comprising: an inner cylindrical body provided with the core wire holding hole; and an outer cylindrical body provided with a tapered portion at a distal end, wherein the inner cylindrical body is formed into an outer cylindrical body. 4. The optical fiber ferrule according to claim 1, wherein said fixed space portion is formed by being inserted. 5. The inner cylindrical body according to claim 4, wherein said inner cylindrical body and said outer cylindrical body come into contact with each other, and a threaded groove is provided on a peripheral surface of said outer cylindrical body, and said inner cylindrical body is screwed and fixed to said outer cylindrical body. Ferrule for optical fiber.