JPH0545534A - Ferrule for optical connector - Google Patents

Abstract

(57) [Summary] [Object] To provide an optical connector capable of easily and reliably fixing an inner sleeve receiving an optical fiber to a ferrule. [Structure] An optical connector ferrule 1 comprises an outer ferrule 2 having a through hole extending in a longitudinal direction, and an inner ferrule 3 holding an optical fiber 5 and press-fitted into the through hole. The inner ferrule 3 has a pair of optical fiber holding portions 3 which are divided into two along the longitudinal axis at least in a portion holding the optical fiber.
1, 32, and these optical fiber holding portions 31, 32
Optical fiber receiving grooves 35 extending along the longitudinal axis are formed on the divided surfaces facing each other.
The inner ferrule 3 has the optical fiber receiving groove 35.
The optical fiber 5 is sandwiched between them. When the optical fiber 5 is sandwiched in this manner and the optical fiber 5 is press-fitted into the through hole of the outer ferrule 2, both split surfaces are brought into non-contact with each other. Is configured to be.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical connector ferrule used for connecting optical fibers to each other.

[Prior Art]

In a connector for connecting an optical fiber used as a data transmission medium, the end portion of the optical fiber to be connected is inserted into a ferrule and attached, and the ferrules are brought into contact with each other to bring the tip end face of the optical fiber into contact. It is designed to be connected. In such an optical connector, it is necessary to fix the optical fiber so as not to come out of the ferrule. As the fixing method, there are a method of adhering each member with an adhesive, a method of crimping the ferrule in the radial direction thereof (see Japanese Patent Laid-Open No. 57-138611), and the like.

Further, in Japanese Unexamined Patent Publication No. 3-167506, a ferrule is composed of an outer ferrule having a longitudinal through hole and an inner ferrule which holds an optical fiber and is press-fit into the through hole. A ferrule provided with a slit extending in the axial direction from the rear end to the front end in the press-fitting direction has been proposed. With this ferrule, when the inner ferrule is press-fitted into the outer ferrule, the inner ferrule is deformed inward in the radial direction due to the slit, and the press-fitting acts as a clamping force for the optical fiber. The optical fiber can be fixed without performing.

[0004]

In the method using an adhesive, it takes a considerable time to cure the adhesive.
When producing a large number of optical connectors, there is a problem that productivity is not so good. In addition, the caulking method has a problem in that it is difficult to set the caulking amount, for example, the optical fiber is deformed or easily comes out of the sleeve unless the caulking amount (force) is properly set. In particular, when crimping a large number of optical connectors by hand, careful crimping and poor workability are required to uniformly crimp all of them.

On the other hand, in the case of the method of providing the slit on the inner ferrule, such a problem does not occur, but the clamping force of the optical fiber by the inner ferrule is likely to vary, and the clamping of the optical fiber becomes unstable. There is a problem that it is easy. In particular, when the inner ferrule is press-fitted into the outer ferrule, the slit surfaces may come into contact with each other along with the deformation of the inner ferrule to prevent further deformation, and a sufficient optical fiber clamping force may not be obtained. There is. The present invention has been made in view of the above problems, and provides an optical connector ferrule capable of easily and reliably sandwiching and fixing an optical fiber with a ferrule without the need for bonding, crimping, or the like. The purpose is to do.

[0006]

In order to achieve the above object, an optical connector ferrule of the present invention comprises an outer ferrule having a through hole extending in the longitudinal direction and an outer ferrule holding an optical fiber in the through hole. The inner ferrule is configured to be press-fitted, and the inner ferrule has a pair of optical fiber holding portions divided into two along the longitudinal axis at least in a portion holding the optical fiber. Optical fiber receiving grooves, which extend along the longitudinal axis, are formed on the divided surfaces facing each other. This inner ferrule is configured to sandwich the optical fiber between both optical fiber receiving grooves, and when it is press-fitted into the through hole of the outer ferrule while sandwiching the optical fiber in this way, both split surfaces Are in non-contact with each other.

The inner ferrule may have a prismatic shape or a cylindrical shape (at this time, the through hole of the outer ferrule also has a shape corresponding thereto). The cross-sectional shape of the fiber sandwiching piece may be a fan shape that expands with the optical fiber receiving groove as a key. Further, the inner ferrule may be composed of a pair of optical fiber sandwiching pieces which are divided into two along the longitudinal axis, and in this case, the splitting surfaces of the both optical fiber sandwiching pieces, which face each other, are respectively separated by the longitudinal axis. An optical fiber receiving groove extending along the optical fiber receiving groove is formed, and the inner ferrule is configured to hold the optical fiber between the two optical fiber receiving grooves in a state where both optical fiber holding pieces are overlapped so that the split surfaces face each other. Is preferred. Further, when the inner ferrule is divided into two parts as described above, it is preferable to hinge the ends of the optical fiber holding pieces to each other.

[0008]

In such an optical connector, the inner ferrule is press-fitted into the through hole of the outer ferrule with the optical fiber sandwiched between the optical fiber receiving grooves formed on the split surfaces of the two optical fiber sandwiching portions. At this time, since the split surfaces do not come into contact with each other, all of the compressive force generated by the press-fitting is concentrated on the contact surface of each optical fiber receiving groove with the optical fiber as the clamping force of the optical fiber. To work. As a result, the optical fiber is firmly sandwiched and fixed by the ferrule. If the inner ferrule is divided into two parts, the optical fiber receiving groove and the press-fitted portion can be easily formed. In this case, the tips of the optical fiber holding pieces constituting the inner ferrule are hinged to each other, whereby the optical fiber holding pieces can be easily overlapped.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described below with reference to the drawings. First, FIG. 1 shows a ferrule 1 for an optical connector according to the present invention. This ferrule 1
Is composed of an outer ferrule 2 formed in a stepped columnar shape whose diameter decreases toward the tip, and an inner ferrule 3 that holds the optical fiber 5 and is press-fitted into the outer ferrule 2.

The outer ferrule 2 is composed of a resin outer member 2a and a metal tube 2b as shown in the side cross section of FIG. A press-fitting hole 2c is formed in the outer member 2a so as to extend in the longitudinal direction from the vicinity of the front end to the vicinity of the rear end. A guide hole 2d having a funnel-shaped portion extending in the longitudinal direction and opening to the press-fitting hole 2c side is formed in front of the press-fitting hole 2a. The tip of the guide hole 2d is open at the tip surface of the outer member 2a. Further, the press-fitting hole 2c is provided behind the press-fitting hole 2c.
A positioning hole 2e having a larger diameter and opening at the rear end face is formed. Further, the tube 2b is press-fitted into the press-fitting hole 2c.

The inner ferrule 3 is made of resin. The inner ferrule 3 has a substantially cylindrical longitudinal shape as shown in FIG. 3, and has a small-diameter press-fitting portion 3a extending from the front end to the rear end and a large-diameter positioning portion provided near the rear end. 3b and a small-diameter end portion 3c extending from there to the rear end portion. Further, a tapered portion 3e is formed at the tip of the inner ferrule 3. However, this inner ferrule 3
Along the longitudinal axis of the two clamping pieces (first clamping piece 31
And a second sandwiching piece 32). 4 and 5 show a state in which the two sandwiching pieces 31 and 32 are split and opened.

Both the center of the dividing surface of the first holding piece 31 and the second holding piece 32 have receiving grooves 35 extending in the longitudinal direction.
35 is formed. Each receiving groove 35 has a small diameter (hereinafter, this portion is referred to as a small diameter receiving groove 35a) from the tip to the middle portion of the press-fitting portion 3a, and from the middle portion to the end portion 3c.
The large diameter (hereinafter, this portion is the large diameter receiving groove 3
5b) is formed in steps. On both sides near the rear end of the small-diameter receiving groove 35a on the split surface of the press-fitting portion 3a, an intermediate dowel 36 is formed on one side (left side toward the tip direction) and an intermediate dowel receiving hole 37 is formed on the other side (right side thereof). Has been done. A rear end dowel 38 is formed on the other side (same right side) of the large-diameter receiving groove 35a on the split surface of the positioning portion 3b, and a rear end dowel receiving hole 39 is formed on one side (same left side) thereof. Furthermore, both clamping pieces 31, 32
The tips are flexibly connected by a hinge 41. However, the hinge 41 is provided in two forks while avoiding the periphery of the tip opening of the small diameter groove 35a.
The sandwiching pieces 31, 32 and the hinge 41 are integrally formed with the sandwiching pieces 31, 32 opened as shown in the figure.

Both sandwiching pieces 31, 32 formed in this way
While bending the hinge 41,
Each dowel receiving hole 3 formed in the opposite holding piece.
The inner ferrule 3 as shown in FIG. 3 can be easily assembled by fitting them so as to be received by 7, 39. By the way, as shown in FIG. 6, the cross section from the vicinity of the front end to the rear end of the press-fitting portion 3a of each holding piece 31, 32 has a small diameter receiving groove 35a and a large diameter receiving groove 35b.
It has a fan shape that spreads at the center. On the other hand, the tip of the press-fitted portion 3a, the cross-section of the positioning portion 3b, and the cross-section of the end portion 3c are semicircles that widen around the small-diameter receiving groove 35a or the large-diameter receiving groove 35b, respectively. Therefore, in the inner ferrule 3 assembled as described above, the split surfaces of the semicircular cross section contact each other, and the split surfaces of the fan-shaped cross section from the front end to the rear end of the press-fitted portions 3a, 3a are not joined to each other. They are maintained in non-contact with each other (hereinafter, this part is referred to as a non-contact part in the press-fitting parts 3a, 3a). That is, as shown in FIG. 7 and FIG.
Fan-shaped slits 55, 55 are formed between the two non-contact portions. Although the inner ferrule 3 has a complicated structure as described above, it is possible to easily manufacture the inner ferrule 3 by dividing the inner ferrule 3 into two and integrally molding the open state as described above. Is possible.

Thus, the inner ferrule 3 has a space surrounded by the small-diameter receiving grooves 35a, 35a at the top and bottom, that is, the wire receiving passage 51 is formed, and the large-diameter receiving grooves 35b, 35b cover the entire circumference. The enclosed space, that is,
The core wire receiving passage 52 is formed. Then, as shown in FIG. 3, in the strand receiving passage 51 and the core receiving passage 52, the strand portion 5a and the core portion of the optical fiber 5 (the portion coated with the strand 5a for protecting the strand 5a), respectively. 5b is attached, and the optical fiber 5 is received by the inner ferrule 3. Therefore, each sandwiching piece 31, 3
The non-contact parts (3a, 3a) of 2 receive the optical fiber 5 while sandwiching the optical fiber 5 in a non-contact state. The optical fiber 5 may be attached by inserting the optical fiber 5 into the inner ferrule 3 in a state where the sandwiching pieces 31 and 32 are overlapped with each other as shown by the arrow in FIG.
Alternatively, the sandwiching pieces 31 and 32 may be overlapped so that the optical fiber 5 is sandwiched between the sandwiching pieces 31 and 32. At the time of this attachment, the wire portion 5a is projected from the tip of the inner ferrule 3 to some extent.

Further, the inner ferrule 3 having thus received the optical fiber 5 is press-fitted into the tube 2b attached to the outer ferrule 2 from the tip side thereof, as shown in FIG. When press-fitting, the press-fitting can be easily performed by utilizing the tapered portion 3e provided at the tip of the inner ferrule 3. Further, since the hinge part 41 is folded at the tip of the press-fitting part 3a and does not spread to the side of the press-fitting part 3a, it does not interfere with the press-fitting. On the other hand, the press-fitting depth of the inner ferrule 3 with respect to the outer ferrule 2 is determined by bringing the end surface of the positioning portion 3b of the inner ferrule 3 into contact with the end surface of the positioning hole 2e of the outer ferrule 2. It should be noted that, at the time of press-fitting, the wire portion 5 a of the optical fiber 5 protruding from the tip of the inner ferrule 3
While being guided by the guide hole 2d formed in the outer ferrule 2, it projects outside the tip of the outer ferrule 2 through its tip opening.

Here, the non-contact portions (3a, 3a) of the sandwiching pieces 31, 32 of the inner ferrule 3 are maintained in the non-contact state after the press-fitting due to the presence of the optical fiber 5. Then, as shown in FIG. 9, all the compressive forces generated by the press-fitting are the force (clamping force F) that the non-contact portions (3a, 3a) clamp the optical fiber 5 therebetween.
Acts intensively on the periphery (contact surface with the optical fiber 5) of. Therefore, by appropriately setting the magnitude of the compression force, that is, the magnitude (smallness) of the inner diameter of the tube 2b with respect to the outer diameter of the inner ferrule 3, the optical fiber 5
It is possible to obtain an appropriate clamping force for preventing the optical fiber 5 from coming off from the inner ferrule 3 without being deformed. Furthermore, when assembling a plurality of such ferrules 1, all ferrules 1 can be easily assembled.
With regard to the above, the clamping force can be made uniform.

The protruding portion of the ferrule 1 from the outer ferrule 2 is cut along the tip surface of the outer ferrule 2. Thus, the assembly of the ferrule 1 is completed.

In the above embodiment, the outer ferrule 2 is made up of the resin outer member 2a and the metal tube 2b press-fitted into the resin outer member 2a.
The pressure input is received by the metal tube 2b so that the resin outer member 2a is not damaged. Further, in the case of such a configuration, the clamping force of the optical fiber 5 can be adjusted or the optical fibers having different diameters can be attached by replacing the same resin outer member 2a with a metal tube having a different inner diameter. You can On the other hand,
As shown in FIG. 10, the outer ferrule 2'may be integrally formed of metal. As a result, when assembling the ferrule 1 ', the troublesome work of press-fitting the tube 2b into the outer member 2a as in the above embodiment can be eliminated. Furthermore, sufficient strength can be obtained.

In the above embodiment, the inner ferrule 3 was divided over the entire longitudinal direction, but, for example, only the press-fitting portion 3a is divided along the longitudinal axis, and the other portions (positioning portion 3b and end portion 3c) are integrally molded. There is no problem even if it is done. Further, although the inner ferrule 3 is formed in a cylindrical shape, it may be formed in a prismatic shape. However, in this case, the press-fitting hole 2c of the outer ferrule 3 into which the inner ferrule 3 is press-fitted also needs to have a shape corresponding to the outer shape of the inner ferrule 3.

In the above embodiment, the receiving groove 35 (35
Although a and 35b) are formed in a semicircular shape, the receiving groove in the optical connector according to the present invention is not limited to this.
For example, as shown in FIG. 11, the receiving groove 35 '(35
a ', 35b') may be formed in a V shape. further,
In the above embodiment, the cross-sectional shape of the non-contact portion of the press-fitting portion 3a is set so that the slit 55 is formed in a fan shape, but as shown in FIG. 12, a cross-sectional shape such that parallel slits 55 'are formed. The shape is also acceptable. Further, in the above-described embodiment, the hinge 41 for connecting the sandwiching pieces 31 and 32 is provided, but the hinge 41 may not be provided.

By the way, the ferrule 1 constructed and assembled as described above has, for example, FIGS.
As shown in FIG. The two-core connector housing 120 includes a main body housing 121 and a cover housing 122.
The main body housing 121 forms the lower half of the two-core connector housing 120 in FIG. 14, and is provided with two connector receiving ports 121a and 121a at its tip. Ferrule 1 in each connector receptacle 121a
Is inserted from the inside of the main body housing 121 toward the tip direction. The insertion and positioning of the ferrule 1 with respect to the main body housing 121 is performed by contacting the tip end side surface of the stepped portion at the rear end of the outer ferrule 2 with the periphery of the insertion opening of the connector receiving opening 121a.
Further, the outer ferrule 2 is urged toward the front end of the main body housing 121 by a spring 123 attached between the rear end side surface of the rear end stepped portion and the inner wall of the main body housing 121. As a result, the ferrule 1 is held in the connector receiving opening 121a in a state in which the retractable movement against the biasing force of the spring 123 is allowed.
The optical fiber 5 (core wire portion 5b) extending from the two ferrules 1 held by the main body housing 121 extends to the outside of the main body housing 121 through the inside of the cover cable 125 fixed to the rear end of the main body housing 121. ing.

The cover housing 122 is formed by removing the connector receiving opening 121a from the main body housing 121, and as shown in FIG.
2 core connector housing 12 by covering with 21
Form the upper half of 0. In addition, this cover housing 1
As shown in FIG. 12, 22 is fixed to the main body housing 121 with screws 126. Further, the central portion of the tip of the cover housing 12 (two connector receiving ports 1
21a, 121a) and the elastic locking portion 12
2a is provided. When the main two-core connector housing 120 is connected to the mating two-core connector housing (not shown), the elastic locking portion 122a firmly locks these connector housings by using its elastic force.

Thus, the two-core connector housing 12
By connecting 0 to the mating two-core connector housing, the outer ferrules 2 of the ferrule 1 on the main-coaxial connector housing 120 side and the end faces of the outer ferrules of the mating optical connectors are butted against and brought into contact with each other. You can The contact force is automatically and appropriately adjusted by the retracting movement of the ferrule 1 with respect to the connector receiving port 121a. Thus, the butt connection between the two optical fibers is made.

[0024]

As described above, in the ferrule for an optical connector according to the present invention, the inner ferrule has a pair of optical fiber holding portions which are divided into two along the longitudinal axis at least in the portion holding the optical fiber. Then, the optical fiber is configured to sandwich the optical fiber between the optical fiber receiving grooves formed on the facing surfaces of the both optical fiber sandwiching portions, and the inner ferrule sandwiching the optical fiber is inserted into the through hole of the outer ferrule. When press-fitted into, both split surfaces are in non-contact with each other. Therefore, in this non-contact portion (non-contact portion), all the compressive force generated by press fitting into the outer ferrule acts on the optical fiber held in the optical fiber receiving groove via the inner ferrule, Can be firmly clamped and fixed on the ferrule. In this case, the inner ferrule may be formed in a cylindrical shape, and the cross-sectional shape of each optical fiber sandwiching piece may be a fan shape that widens the optical fiber receiving groove.

Further, the inner ferrule is divided into two along the longitudinal axis to be composed of a pair of optical fiber sandwiching pieces, and the optical fibers extending along the longitudinal axis on the split surfaces of these optical fiber sandwiching pieces facing each other. It is preferable that the inner ferrule is formed so as to sandwich the optical fiber between the optical fiber receiving grooves in a state where the fiber receiving groove is formed and both the optical fiber holding pieces are overlapped so that their divided surfaces face each other. With this, an inner ferrule having a complicated shape can be easily manufactured. When the inner ferrule is divided into two parts as described above, it is preferable that the tips of the optical fiber holding pieces are hinged to each other. In this way, it is easy to stack both optical fiber holding pieces. ..

[Brief description of drawings]

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

FIG. 2 is a side sectional view of an outer ferrule in the optical connector.

FIG. 3 is a side view of an inner ferrule and an optical fiber in the optical connector.

FIG. 4 is a plan view showing a developed state of the inner ferrule.

FIG. 5 is a side view showing a developed state of the inner ferrule.

6 is a cross-sectional view taken along line VI-VI in FIG.

7 is a cross-sectional view taken along the line VII-VII in FIG.

FIG. 8 is a side sectional view of the optical connector.

9 is a sectional view taken along line IX-IX in FIG.

FIG. 10 is a side sectional view of the optical connector (however, an embodiment different from that shown in FIG. 8).

FIG. 11 is a cross-sectional view of the inner ferrule (however, an embodiment different from that shown in FIG. 5).

FIG. 12 is a cross-sectional view of the inner ferrule (however, an embodiment different from those shown in FIGS. 5 and 10).

FIG. 13 is a plan view (partially sectional view) of a two-core connector housing using the optical connector.

FIG. 14 is a side view of the two-core connector housing.

[Explanation of symbols]

 1 Optical Connector 2, 2'Outer Ferrule 2a Resin Outer 2b Metal Tube 3 Inner Ferrule 3a Press-fitting Section 31, 32 Clamping Piece 35 Receiving Groove 41 Hinge 55, 55 'Slit 120 Two-Core Connector Housing

Claims (4)

[Claims] 1. An optical connector ferrule comprising an outer ferrule having a through hole extending in a longitudinal direction and an inner ferrule holding an optical fiber and press-fitted into the through hole, wherein the inner ferrule is at least the optical fiber. In the portion that holds the fiber, a pair of optical fiber holding portions that are divided into two along the longitudinal axis are provided, and the split surfaces facing each other of these optical fiber holding portions are respectively along the longitudinal axis. An extending optical fiber receiving groove is formed, and the inner ferrule is configured to hold the optical fiber between the both optical fiber receiving grooves, and thus the inner ferrule holding the optical fiber is used as the outer ferrule. When they are press-fitted into the through holes, the two divided surfaces are not in contact with each other. An optical connector ferrule, characterized in that the. 2. The inner ferrule is formed in a cylindrical shape, and the cross-sectional shape of each optical fiber holding piece is
The ferrule for an optical connector according to claim 1, wherein the ferrule has a fan shape that expands mainly in the optical fiber receiving groove. 3. The inner ferrule is divided into two along the longitudinal axis to be composed of a pair of optical fiber sandwiching pieces, and the split surfaces of the optical fiber sandwiching pieces facing each other are respectively along the longitudinal axis. An optical fiber receiving groove extending therethrough, and the inner ferrule so as to hold the optical fiber between the optical fiber receiving grooves in a state where the optical fiber holding pieces are overlapped so that the split surfaces face each other. The ferrule for an optical connector according to claim 1, wherein 4. The ferrule for an optical connector according to claim 3, wherein the tips of the optical fiber holding pieces are hinged to each other.