JP2000002818A - Optical connector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical connector hardly causing the light transmission loss of an optical fiber in a ferrule and capable of preventing the possibility of break of the optical fiber. SOLUTION: This optical connector 1 has a ferrule 3 incorporated with an optical fiber 5, and the optical fiber 5 is inserted into an optical fiber insertion part 4 extending into the ferrule 3 from an optical connecting port 3A formed on a front end face 3a of the ferrule 3, and projects the tip face 5a of the optical fiber 5 from the optical connecting port 3A, and the optical fiber insertion part 4 is constituted of a non-fixing area P positioned in the vicinity of the front end face 3a of the ferrule 3 and a fixing area N positioned behind the non-fixing area P.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical connector, and more particularly, to an optical connector for connecting optical fibers to each other.

[0002]

2. Description of the Related Art Conventionally, there is JP-A-9-159860 as a technique in such a field. The optical connector described in this publication is for performing optical connection utilizing buckling of an optical fiber. Specifically, an optical fiber is protruded from the distal end surface of the ferrule by a predetermined amount, and a space for bending the optical fiber is formed inside the ferrule to allow buckling of the bowed optical fiber. Therefore, this optical connector is a PC connection (Physical Conta
ct).

[0003]

However, the conventional optical connector has the following problems since it is configured as described above.

That is, when an optical fiber is buckled in a bow shape in the space for bending an optical fiber, an excessive load is applied to the optical fiber due to the buckling, and an optical transmission loss occurs in the optical fiber in the ferrule. In some cases, there is a problem that the optical fiber may be broken.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide an optical connector in which optical transmission loss of an optical fiber hardly occurs in a ferrule and there is no fear of breakage of the optical fiber. Aim.

[0006]

According to a first aspect of the present invention, there is provided an optical connector having a ferrule having a built-in optical fiber, wherein the optical connector extends from an optical connection port formed in a front end face of the ferrule to the inside of the ferrule. An optical fiber is inserted into the extending optical fiber insertion portion, and a distal end surface of the optical fiber is projected from the optical connection port.The optical fiber insertion portion has a non-fixed region located near the front end surface of the ferrule and a non-fixed region. And a fixed region located rearward.

In this optical connector, since the optical fiber is fixed to the ferrule to the vicinity of the front end face of the ferrule, the optical fiber is unlikely to buckle within the ferrule. Moreover, as a result of shortening the non-fixed region, a change in the amount of protrusion of the optical fiber caused by a difference in the thermal expansion coefficient between the ferrule and the optical fiber can be extremely reduced. Therefore, the optical connector of the present invention proposes a new concept of PC connection in order to avoid the problem of PC connection using buckling.

In the optical connector according to the present invention, it is preferable that, in the fixing region, the outer peripheral surface of the optical fiber and the wall surface of the optical fiber insertion portion are bonded by an adhesive. When such a configuration is adopted, it is realized by a simple operation of applying the adhesive to the optical fiber and then inserting the optical fiber into the optical fiber insertion portion, and the optical fiber is quickly and easily inserted into the optical fiber insertion portion. It can be fixed securely.

The optical connector according to claim 3, wherein the optical fiber insertion portion extends from the optical connection port and forms an unfixed region, and a cross section positioned behind the optical fiber positioning hole and forms a fixed region. It is preferable to have a fiber pressing and fixing member which comprises a substantially C-shaped optical fiber alignment groove and presses the optical fiber in the optical fiber alignment groove from above to fix the optical fiber to the wall surface of the optical fiber alignment groove. When such a configuration is adopted, the optical fiber is arranged in the optical fiber alignment groove, and the optical fiber is simply and securely fixed to the ferrule simply by pressing the optical fiber from above with the optical fiber pressing and fixing member. Can be.

In the optical connector according to the present invention, it is preferable that the non-fixed region has a region length of 500 μm or less from the front end surface of the ferrule. Such a region length is preferable for realizing the optical connector of the present invention.

In the optical connector according to the present invention, it is preferable that the distal end face of the optical fiber has been subjected to edge removal processing by electric discharge machining. In this case, the optical fiber can be inserted into the optical fiber insertion portion of the ferrule with the tip of the optical fiber being electrically rounded.

[0012] In the optical connector according to the sixth aspect, it is preferable that an edge removing process is performed on the tip end surface of the optical fiber by polishing. In this case, the optical fiber can be inserted into the optical fiber insertion portion of the ferrule while the tip of the optical fiber is mechanically rounded.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the optical connector according to the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a perspective view showing an optical connector according to the present invention. The optical connector 1 shown in FIG. 1 constitutes the plug side of the SC type connector. This optical connector 1
Are plugged in from both sides of the adapter 2 to enable one-touch connection. The optical connector 1 has therein a ferrule 3 protruding from an end thereof. As shown in FIG. 2, the ferrule 3 is formed of a material such as zirconia, plastic or glass into a cylindrical shape, and This is for fixing the optical fiber 5 exposed from the distal end of the optical fiber core S of the core by removing the coating F inside the core.

As shown in FIGS. 3 and 4, the ferrule 3
An optical fiber insertion portion 4 extending in the central axis direction for loading the optical fiber 5 and a coating portion insertion hole 6 for loading the coating portion F are arranged in a straight line at the center. I have. The optical fiber insertion portion 4 is formed as an optical fiber positioning hole extending over the entire length, and has a diameter of 126 μm with respect to the optical fiber 5 of 125 μm in diameter. It will be inserted into the optical fiber insertion section 4.

The distal end face 5a of the optical fiber 5 projects from the optical connection port 3A by about 2 μm from the front end face 3a of the ferrule 3. Optical fiber insertion part 4
Are a non-fixed area P located near the front end face 3a of the ferrule 3 and a fixed area N located behind the non-fixed area P.
And The non-fixed region P has a length of 500 μm extending inward from the front end face 3 a of the ferrule 3.
m (preferably 50-100 μm),
The non-fixed region P is also a region where there is no liquid substance such as a refractive index matching agent unnecessary for PC connection.

Further, in the optical fiber insertion portion 4, an adhesive (for example, an epoxy-based heat-curable adhesive) R is loaded in the fixing region N, and the outer peripheral surface of the optical fiber 5 and the optical fiber 5 are attached by the adhesive R. The wall of the insertion section 4 is bonded and fixed. As described above, the optical fiber insertion portion 4 is filled with the adhesive R except for a small non-fixed region P located near the front end face 3a of the ferrule 3. The covering portion F of the optical fiber S is inserted into the covering portion insertion hole 6, and the outer peripheral surface of the covering portion F and the wall surface of the covering portion insertion hole 6 are adhered and fixed by the adhesive R.

Here, the optical fiber S is connected to the ferrule 3
A brief description will be given of the procedure for assembling the device with an example.

First, the coating portion F on the front side of the optical fiber core S
Is removed by a predetermined length, the optical fiber 5 is exposed from the tip of the optical fiber core wire S, and then the optical fiber 5 is cut into a predetermined length by a cutter or the like. Thereafter, as shown in FIG. 5, the tip end surface 5a of the optical fiber 5 is subjected to electric discharge machining to make it into a spherical shape, and an edge removal process is performed. The biggest reason for performing the electric discharge machining is that the burr on the tip end surface 5a of the optical fiber 5, which is a factor that hinders the PC coupling, is removed and the end surface is rounded, so that the PC coupling can be easily performed. The optical fiber 5 is easily inserted into the optical fiber insertion section 4 of the ferrule 3. As shown in FIG. 6, the distal end face 5a of the optical fiber 5 may be chamfered by a polishing rotor or mechanical polishing by hand, and the edge removal processing of the distal end face 5a of the optical fiber 5 may be performed. .

After such end face processing, the optical fiber 5 is inserted into the optical fiber insertion portion 4 of the ferrule 3. At this time, the optical connection port 3 A of the ferrule 3 is made to correspond to the non-fixed area P. , A grease-like refractive index matching agent or an elastic adhesive is packed in advance. Then, with a predetermined amount of adhesive R applied to the optical fiber 5 and the covering portion F, the optical fiber 5 is inserted into the optical fiber insertion portion 4 from the rear, and the front end surface 5a of the optical fiber 5 is connected to the front end surface of the ferrule 3. It is pushed in so as to project about 2 μm from 3a.

In this case, the tip of the optical fiber 5 is inserted so as to be sunk into the refractive index matching agent, and when the optical fiber 5 advances, the adhesive R applied to the optical fiber 5 is used.
Is excluded from the surface of the optical fiber 5 by the phenomenon of removing the adhesive of the refractive index matching agent having a large viscosity. As a result, the adhesive R is not attached to the tip portion of the optical fiber 5 that has passed through the refractive index matching agent, and the optical fiber 5 to which the adhesive R is not attached protrudes from the ferrule 3. After the adhesive R is cured, the refractive index matching agent is removed, so that the portion where the refractive index matching agent was present is formed as the non-fixed region P in the optical fiber insertion section 4. .

The refractive index matching agent or the elastic pressure-sensitive adhesive is
Instead of being packed in the optical connection port 3A in advance, the optical fiber 5 may be abutted with the distal end face 5a of the ferrule 3 projecting from the front end face 3a. Further, the optical fiber insertion portion 4 of the ferrule 3 may be filled with the adhesive R in advance.

Next, an optical connector 7 according to another embodiment will be described. This optical connector 7 is an optical connector that does not use an adhesive.

As shown in FIG. 7, the front end face 8a of the ferrule 8 is formed flat so as to achieve the end face butting with the mating optical connector, and at the center of the front end face 8a,
An optical connection port 9 for projecting the optical fiber 5 is provided. Optical connectors 7 are provided on both sides of the optical connection port 9.
A guide pin insertion hole G used for connection between them is provided.

As shown in FIGS. 7 and 8, the ferrule 8
Inside, a single optical fiber insertion portion 10 extending in the longitudinal direction for inserting the optical fiber 5 is formed in a straight line. The optical fiber insertion portion 10 has an optical fiber positioning hole 11 extending from the optical connection port 9 and used as a non-fixed area P, and a cross-sectional view located behind the optical fiber positioning hole 6 and used as a fixed area N. It comprises a C-shaped optical fiber alignment groove 12. Above the optical fiber alignment groove 12, a block-shaped optical fiber pressing and fixing member 13 is disposed, and the fiber pressing and fixing member 13 is disposed in a housing 14 described later.

In addition, behind the optical fiber alignment groove 12,
A tapered (for example, funnel-shaped) optical fiber guide hole 10A is provided in consideration of insertion of the optical fiber 5, and the optical fiber positioning hole 11, the optical fiber alignment groove 12, and the optical fiber guide hole 10A are arranged in a straight line. ing. Therefore, when the tip of the optical fiber 5 is inserted from the optical fiber guide hole 10A, the optical fiber 5 is
2 and reaches the optical fiber positioning hole 11.

Further, the ferrule 8 is provided with a fiber pressing / fixing member housing portion 14 for housing the fiber pressing / fixing member 13, and the top of the housing portion 14 has a top for inserting the fiber pressing / fixing member 13. The opening 15 is formed as a rectangular opening 15, and the opening 15
c. An optical fiber alignment groove 12 having a substantially C-shaped cross section is formed on the bottom surface 14a of the housing portion 14 and extends over the entire length thereof.

When the fiber pressing and fixing member 13 is inserted through the opening 15, the fiber pressing and fixing member 13 can be arranged in the optical fiber alignment groove 12, and the optical fiber 5 in the optical fiber alignment groove 12 is The lower surface 13b of the pressing and fixing member 13 can be pressed down from above (see FIG. 9). Therefore, in the optical fiber insertion section 10, the fixing region N is formed with substantially the entire length of the fiber pressing and fixing member 13. Then, the non-fixed area P is formed in front of the fixed area N.
The non-fixed area N having an area length of not more than 00 μm (preferably about 50 to 100 μm) is
Is secured by

Further, the optical connector 7 is provided with a spring member 1 for urging the fiber pressing and fixing member 13 inserted into the housing portion 14.
The spring member 16 is provided on the upper surface 8 of the ferrule 8.
The fiber pressing and fixing member 13 is elastically held in the accommodating portion 14 by a clamp member 16 extending from c to the lower surface 8d and having a U-shaped cross section. Also, the upper surface 13 of the fiber pressing and fixing member 13
A is provided with a protrusion 17 extending in the longitudinal direction, and the spring force of the clamp member 16 is transmitted to the fiber pressing and fixing member 13 via the protrusion 17.

By using phosphor bronze or cold-worked stainless steel as the material of the clamp member 16, the clamp member 16 having a strong spring force and high durability can be obtained, and the long-term reliability of the clamp force is ensured. I do. Further, the clamp member 16 is formed in a U-shape from a plate-shaped upper piece 16a, a lower piece 16b, and an intermediate piece 16c for connecting the upper piece 16a and the lower piece 16b, and creates an appropriate clamping force by the upper piece 16a of the clamp member 16. .

Further, as shown in FIGS. 7 and 8, a coating portion F of the optical fiber S is fixed to the ferrule 8 separately from the fiber pressing and fixing member 13 for fixing the optical fiber 5 to the ferrule 8. And a covering member pressing and fixing member 20 in the form of a block.

Inside the ferrule 8, a covering portion seating groove 22 having a V-shaped cross section located behind the funnel-shaped optical fiber guide hole 10A is provided, and the covering portion seating groove 22 accommodates the covering portion F. It is formed as a V-groove having a width. The covering portion seating groove 22 is formed on the bottom surface of the covering portion pressing / fixing member housing portion 21 arranged in parallel with the fiber pressing / fixing member housing portion 14 described above. The fixing member 20 is arranged.

Further, the optical connector 7 has a spring member 23 for urging the covering portion pressing and fixing member 20 in the housing portion 21.
The spring member 23 is configured as a clamp member having a U-shaped cross section extending from the upper surface 8c to the lower surface 8d of the ferrule 8, and the cover member pressing and fixing member 20 is elastically moved in the housing portion 21 by the clamp member 23. Holding spontaneously. Further, a projection 24 extending in the longitudinal direction is provided on the upper surface 20 a of the covering portion pressing and fixing member 20, and the covering portion F is pressed into the covering portion insertion groove 22 by the covering portion pressing and fixing member 20. Fixed.

By using phosphor bronze or cold-worked stainless steel as the material of the clamp member 23, the clamp member 23 having a strong spring force and high durability can be provided, and long-term reliability of the clamp force is ensured. I do. The clamp member 23 is formed in a U-shape from a plate-shaped upper piece 23a, a lower piece 23b, and an intermediate piece 23c for connecting the upper piece 23a and the lower piece 23b, and creates an appropriate clamping force by the upper piece 23a of the clamp member 23. .

Next, an optical connector 30 according to still another embodiment will be described. This optical connector 30 is an adhesive type optical connector.

The optical connector 30 shown in FIG. 10 has a ferrule 32. The ferrule 32 is provided with an optical fiber bonding recess 33 for accommodating an adhesive R. It is formed as a rectangular opening 34 through which the agent R flows. Then, an optical fiber insertion portion 37 is formed in the ferrule 32 and the concave portion 33 is formed.
An optical fiber alignment groove 35 having a C-shaped cross section extending over the entire length thereof is formed in the bottom surface 33a, and an optical fiber positioning hole 36 is formed in front of the groove (see FIG. 11).

Therefore, similarly to the optical connector 1 shown in FIG. 1, the optical fiber 5 after the application of the adhesive R is filled with the refractive index matching agent or the like in the optical connection port 38 of the ferrule 32.
Is inserted into the optical fiber insertion portion 37, and the tip of the optical fiber 5 is projected from the front end face 32a of the ferrule 32. Thereafter, when the adhesive R is poured from the opening 34, the optical fiber 5 in the optical fiber insertion portion 37 is fixed to the ferrule 32 by the adhesive R, and this becomes the fixing region N. Then, the portion from which the refractive index matching agent has been removed becomes the non-fixed region P.

At the rear end of the ferrule 32, there is formed a coating bonding recess 38 arranged in parallel with the optical fiber bonding recess 33 described above. F indicates the ferrule 32 by the adhesive R.
Fixed securely.

Here, in the present invention, the cut end of the optical fiber 5 is used to ease the end face angle of the end face 5a of the optical fiber 5 used at the time of cutting.
In some cases, a discharge is given to the battery to make it round. For example, when the end face 5a of the optical fiber 5 has an angle of 1.5 °, the distance from the tip of the optical fiber 5 to the center of the core is about 1.6.
It has a distance of about μm. Therefore, if a discharge is applied to the front end face 5a and the front end face 5a is processed to have a radius of curvature of 1.0 mm, the optical fiber 5 having such a radius of curvature still needs to be deformed and subjected to PC. For this purpose, as shown in FIG. 12, in consideration of this, it is necessary to project the distal end face 5a of the optical fiber 5 from the front end face 3a of the ferrule 3. It should be noted here that the tip angle 5a of the optical fiber 5 hardly has a cutting angle of 1.5 ° or more. However, as a precaution, the protrusion amount of the optical fiber 5 is about 1 to 2 μm, and about 5 μm at the maximum. I do.

On the other hand, as shown in FIG. 13, in the conventional ferrule 100, after the optical fiber 101 is attached to the ferrule 100 to realize a PC, precision polishing is performed, and the distal end face of the optical fiber 101 is formed. 101a is processed into a spherical surface. The radius of curvature at that time is about 20 mm, and this spherical surface is the front end face 100a of the ferrule 100.
Slightly protruding from the PC, facilitating the PC. However, in reality, as many as four types of precision polishing processes are required, and the ratio of the cost to the production cost of the optical connector is large.
This has been a problem in reducing costs.

It should be noted that the present invention is not limited to the above-described embodiment, and that the optical fiber core S may be 2 to 1
The optical connector may be of any type such as FC type, SC type, MT type and the like.

[0042]

As described above, the optical connector according to the present invention has the following advantages. That is, in an optical connector having a ferrule with a built-in optical fiber, an optical fiber is inserted into an optical fiber insertion portion extending from the optical connection port formed on the front end surface of the ferrule toward the inside of the ferrule, and the distal end surface of the optical fiber is inserted. Protruding from the optical connection port, the optical fiber insertion portion has a non-fixed region located near the front end face of the ferrule and a fixed region located behind the non-fixed region, so that the optical fiber insertion portion within the ferrule It is possible to provide an optical connector in which transmission loss hardly occurs and the optical fiber is not likely to break.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an embodiment of an optical connector according to the present invention.

FIG. 2 is a perspective view showing a ferrule adapted to the optical connector of FIG. 1;

FIG. 3 is a longitudinal sectional view of the ferrule of FIG. 2;

FIG. 4 is an enlarged sectional view of a main part of FIG.

FIG. 5 is an enlarged side view showing a state where the distal end surface of the optical fiber is subjected to electric discharge machining.

FIG. 6 is an enlarged side view showing a state in which the distal end surface of the optical fiber is polished.

FIG. 7 is an exploded perspective view showing another embodiment of the optical connector according to the present invention.

8 is a longitudinal sectional view of the optical connector shown in FIG.

FIG. 9 is an enlarged cross-sectional view showing a state where an optical fiber is fixed in an optical fiber alignment groove.

FIG. 10 is a sectional view showing still another embodiment of the optical connector according to the present invention.

11 is an enlarged sectional view of a main part of the optical connector shown in FIG.

FIG. 12 is an enlarged sectional view showing a state in which an optical fiber is inserted into a ferrule in the optical connector of the present invention.

FIG. 13 is an enlarged sectional view showing a state in which an optical fiber is inserted into a ferrule in a conventional optical connector.

[Explanation of symbols]

P: non-fixed area, N: fixed area, R: adhesive, 1, 7,
30 ... optical connector, 3,8,32 ... ferrule, 3a,
8a, 32a ... front end face of ferrule, 3A, 9, 38 ...
Optical connection ports, 4, 10, 37: optical fiber insertion section, 5: optical fiber, 5a: distal end face of optical fiber, 11, 36: optical fiber positioning hole, 12, 35: optical fiber alignment groove,
13: Fiber pressing fixing member.

 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toshiaki Kakii 1-chome Taya-cho, Sakae-ku, Yokohama-shi, Kanagawa F-term in Sumitomo Electric Industries, Ltd. Yokohama Works 2H036 BA03 CA02 CA08 GA12 GA22 GA23

Claims (6)

[Claims] An optical connector having a ferrule with a built-in optical fiber, wherein an optical fiber insertion portion extending from the optical connection port formed on the front end face of the ferrule toward the inside of the ferrule is provided.
An optical fiber is inserted, a tip end surface of the optical fiber is projected from the optical connection port, and the optical fiber insertion portion is a non-fixed area located near the front end face of the ferrule, and a rear side of the non-fixed area. An optical connector, comprising: 2. The optical connector according to claim 1, wherein in the fixing region, an outer peripheral surface of the optical fiber and a wall surface of the optical fiber insertion portion are adhered by an adhesive. 3. The optical fiber insertion portion includes an optical fiber positioning hole extending from the optical connection port and forming the non-fixed region, and a cross section substantially C which is located behind the optical fiber positioning hole and forms the fixed region. It has a fiber pressing and fixing member which comprises a U-shaped optical fiber alignment groove, presses the optical fiber in the optical fiber alignment groove from above, and fixes the optical fiber to the wall surface of the optical fiber alignment groove. The optical connector according to claim 1. 4. The optical connector according to claim 1, wherein the non-fixed region has a region length of 500 μm or less from the front end surface of the ferrule. 5. The optical connector according to claim 1, wherein the distal end face of the optical fiber has been subjected to edge removal processing by electric discharge machining. 6. The optical connector according to claim 1, wherein the distal end surface of the optical fiber is subjected to an edge removal process by polishing.