JPH0560943A - Ferrule for optical connector - Google Patents

Abstract

PURPOSE:To easily and surely hold and fix an optical fiber in a ferrule without requiring adhesion, caulking, etc. CONSTITUTION:A ferrule 1 for connector consists of an outer ferrule 2 provided with a through hole extending in a longitudinal direction and an inner ferrule 3 for which an optical fiber 5 is inserted into an insertion hole formed through along a center axis and is press-fitted into the through hole. The inner ferrule 2 is provided with slits 36 and 37 which pierce the ferrule 2 in a diameter direction through insertion holes 35a and 35b and are extended in the axial direction. When the optical fiber 5 is inserted into insertion holes 35a and 35b and the inner ferrule 3 is press-fitted to the through hole of the outer ferrule 2 in this state, parts where slits 36 and 37 are formed receive this press-fitting force to hold the optical fiber 5 therebetween and at this time, slit faces 36a and 37a facing each other which form the slits 36 and 37 are in the non-contacting state.

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 Laid-Open Patent Publication No. 3-167506, a ferrule is constructed by an outer ferrule having a longitudinal through hole and an inner ferrule which holds an optical fiber and is press-fitted 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 according to the present invention comprises an outer ferrule having a through hole extending in a longitudinal direction, and an insert formed so as to penetrate along a central axis. The inner ferrule is formed by inserting an optical fiber into the hole and press-fitting into the through hole, and the inner ferrule has a slit formed through the insertion hole in the radial direction and extending in the axial direction. ing. Then, when the inner ferrule is pressed into the through hole of the outer ferrule with the optical fiber inserted in this insertion hole, the portion where the slit is formed receives this press input and holds the optical fiber. Further, at this time, the opposing slit surfaces that form the slits are configured to be in non-contact with each other.

The optical fiber is composed of a fiber core wire formed by covering the fiber element wire with a covering member. The optical fiber is formed with the insertion hole of the inner ferrule exposed at the tip. A fiber receiving hole and a core wire receiving hole are formed so as to receive the fiber, and the inner ferrule has a first slit radially passing through the wire receiving hole and a radial direction passing through the core wire receiving hole. It is preferable to form a second slit that penetrates through. Also,
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 to this). However, when the inner ferrule is formed into a cylindrical shape, the slit in the inner ferrule is formed. It is preferable that the cross-sectional shape of the open portion is a pair of fan-shaped members that face each other and widen with an insertion hole.

In the ferrule for an optical connector having such a structure, the inner ferrule is press-fitted into the through hole of the outer ferrule with the optical fiber inserted in the insertion hole. For this reason, the portion where the slit is formed receives the pressure input and sandwiches the optical fiber, but at this time, since the opposing slit surfaces that form the slit are configured to be in non-contact with each other, All of the compression force generated by the press-fitting acts intensively as the clamping force of the optical fiber. As a result, the optical fiber is firmly sandwiched and fixed by the ferrule. In addition, when the insertion hole of the inner ferrule is formed from the wire receiving hole and the core wire receiving hole and the first slit and the second slit penetrating these receiving holes are formed, the inner ferrule is press-fit into the through hole. By doing so, the optical fiber element wire is held in the element wire receiving hole and the optical fiber core wire is held in the core wire receiving hole.

[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 21 and a metal tube 22, as shown in the side cross section of FIG. A press-fitting hole 2a is formed in the outer member 21 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 2b having a funnel-shaped portion extending in the longitudinal direction and opening to the press-fitting hole 2a side is formed in front of the press-fitting hole 2a. The tip of the guide hole 2b is open on the tip surface of the outer member 21. The press-fitting hole 2a is located behind the press-fitting hole 2a.
A positioning hole 2c having a larger diameter and opening at the rear end face is formed. Further, the tube 22 is press-fitted into the press-fitting hole 2a.

The inner ferrule 3 is made of resin. This inner ferrule 3 is shown in FIGS.
As shown in Fig. 5, it has a substantially cylindrical longitudinal shape and has a relatively small diameter press-fitting portion 31 located on the tip side, a large-diameter flange-shaped positioning portion 32 located at the center, and a small diameter located on the rear end side. And an end portion 33 that is formed. Press fitting part 31
Two circumferential grooves 31c, 31c are formed on the outer peripheral surface of the press-fitting portion 31, and the outer peripheral surface of the press-fitting portion 31 is the first and second press-fitting outer peripheral surfaces 3.
It is divided into 1a and 31b. Further, the press-fitting portion 31 has a tapered guide portion 31c having a taper portion at the tip thereof.
Are formed.

The inner ferrule 3 is formed with an insertion hole 35 penetrating in the longitudinal direction along the central axis thereof. However, the insertion hole 35 is composed of a small-diameter wire receiving hole 35a located on the front end side and a large-diameter core wire receiving hole 35b located on the rear end side. Furthermore, as shown in FIG. 6 (A) showing a cross section taken along the arrow AA in FIG.
5a and a first slit 36 that penetrates in the radial direction and extends in the axial direction, and passes through the core wire receiving hole 35b as shown in FIG. 6B showing a cross section taken along the arrow BB of FIG. The inner ferrule 3 is formed with a second slit 37 that penetrates in the radial direction and extends in the axial direction. As shown in FIG. 6, these first and second slits 36,
Both 37 are formed so as to spread outward from the central portion. For this reason, the cross-sectional shape of the portion where the slits 36 and 37 are formed has a pair of fan shapes that require the wire receiving hole 35a and the core receiving hole 35b, respectively, and the slit surfaces 36a and 37a are mutually formed. Oppose away.

As shown in FIG. 5, the optical fiber 5 has an optical fiber wire 5a through which an optical signal flows, and a core wire 5b is formed by covering the wire 5a. This optical fiber 5 has the ferrule 1 with the strand 5a exposed at the tip (as shown in FIG. 5).
Attached to. In this attachment, first, the tip of the optical fiber 5 is inserted into the insertion hole 35 of the inner ferrule 3 from the rear end side of the inner ferrule 3. As a result, the exposed optical fiber strand 5a at the tip is shown in FIG.
As shown in (A), the tip of the optical fiber core wire 5b is inserted into the wire receiving hole 35a and protrudes from the end surface of the inner ferrule 3 (see FIG. 7). Enter into 35b.

Next, the inner ferrule 3 with the tip of the optical fiber 5 received in the insertion hole 35 is inserted into the press-fitting hole 22a (see FIG. 2) of the metal tube 22 of the outer ferrule 2. , And press-fit as shown in FIG. At this time, the press-fitting depth of the inner ferrule 3 with respect to the outer ferrule 2 is determined by bringing the end face of the positioning portion 32 of the inner ferrule 3 into contact with the end face of the positioning hole 2c of the outer ferrule 2. At the time of press-fitting, the tip of the optical fiber element wire 5a protruding from the tip of the inner ferrule 3 enters into the guide hole 2b formed in the outer ferrule 2 and protrudes outward of the tip of the outer ferrule 2.

The above-mentioned press-fitting is the first of the inner ferrule 3.
The second press-fitting outer peripheral surfaces 31a and 31b are press-fitted into the press-fitting holes 22a of the metal tube 22. Therefore, as shown by the arrow in FIG. 6, a compressive force inward in the radial direction acts on both press-fitted outer peripheral surfaces 31a and 31b. As described above, since the first and second slits 36 and 37 are formed in the portions having the first and second press-fitted outer peripheral surfaces 31a and 31b, the portions are pressed inward by the compressive force. The optical fiber 5 is sandwiched by the inner ferrule 3 in this portion. Specifically, the wire receiving hole 35
The optical fiber 5a inserted into the core a is firmly held in this portion, and the optical fiber core wire 5b inserted in the core receiving hole 35b is firmly held in this portion.

Thus, the first and second slits 36,
The portion formed with 37 receives the above-mentioned compressive force and is deformed inward to sandwich the optical fiber 5. At this time,
Due to this deformation, the slit surfaces 36a facing each other,
37a so that the slits 36 and 3 are not in contact with each other.
A size of 7 is set. Therefore, all the compressive force due to the press-fitting acts as a force for sandwiching the optical fiber 5 (element wire 5a and core wire 5b) via the inner ferrule 2, and the optical fiber 5 can be securely fixed and held by the ferrule 1. .. The magnitude of the compression force by this press fitting is
First and second press-fitted outer peripheral surfaces 31 of the inner ferrule 3
It can be arbitrarily set by changing the press-fitting margin when press-fitting a and 31b into the press-fitting hole 22a of the metal tube 22. Therefore, if a predetermined clamping force suitable for the size, material, etc. of the optical fiber 5 is set, an appropriate clamping force is set so that the optical fiber 5 is not compressed and deformed and does not come out of the ferrule. You can

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, both the first and second slits 36 and 37 are formed so as to spread outward from the central portion as shown in FIG. 6, and the portions where these slits 36 and 37 are formed traverse. The surface shape is the wire receiving hole 35.
a, the core wire receiving hole 35b is formed in a pair of fan shapes. The present invention is not limited to this, and for example, as shown in FIG. 8, slits 36 ', 37' having slit surfaces 36a ', 37a' extending in parallel at a constant interval are formed. You may. However, even in this case, the slit surfaces facing each other have a distance such that the slit surfaces are kept in a non-contact state even if they receive a compressive force at the time of press fitting. Further, in the above embodiment, the first slit 36 corresponding to the strand receiving hole 35a and the second slit 36 corresponding to the core receiving hole 35b.
Although the slit 37 is formed, only one slit may be provided.

In the above embodiment, the outer ferrule 2 is composed of the resin outer member 21 and the metal tube 22 press-fitted into the resin outer member 21, so that the pressure input of the inner ferrule 3 is received by the metal tube 22 and is made of resin. The outer member 21 is prevented from being damaged. In the case of such a configuration, by replacing the same resin outer member 21 with a metal tube having a different inner diameter,
It is possible to adjust the clamping force of the optical fiber 5 or attach optical fibers of different diameters. On the other hand, FIG.
The outer ferrule 2'may be integrally formed of metal as shown in FIG. This allows the ferrule 1 '
In the assembly, the work of press-fitting the tube 22 into the outer member 21 as in the above embodiment can be eliminated. Furthermore, sufficient strength can be obtained.

Although the inner ferrule 3 is formed in a cylindrical shape in the above embodiment, it may be formed in a prismatic shape. However, in this case, the press-fitting hole 22a of the outer ferrule 2 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.

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 body housing 121 is the two-core connector housing 12
The lower half of 0 is formed, and two connector receiving ports 121a, 121a are provided at the tip thereof. The ferrule 1 is inserted into each connector receiving opening 121a from the inside of the main body housing 121 toward the front end 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 has the connector receiving port 12
The retracted movement against the biasing force of the spring 123 is held with respect to 1a. The optical fiber 5 (core wire portion 5b) extending from the two ferrules 1 held in the main body housing 121 is
1 extends to the outside of the main body housing 121 through the inside of the cover cable 125 fixed to the rear end portion.

The cover housing 122 is formed by removing the connector receiving opening 121a from the main body housing 121, and by covering the main body housing 121, the upper half of the two-core connector housing 120 is formed. The cover housing 122 is fixed to the main body housing 121 with screws 126. Further, an elastic locking portion 122a is provided at the center of the tip of the cover housing 12 (a position between the two connector receiving ports 121a, 121a). 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 slit formed so as to extend through the insertion hole in the radial direction and extend in the axial direction. When the inner ferrule is press-fitted into the through-hole of the outer ferrule with the optical fiber inserted in the hole, the slit-formed portion receives this press-fitting force to sandwich the optical fiber. At this time, since the opposing slit surfaces forming the slits are configured to be in non-contact with each other, all of the compressive force generated by the press-fitting acts intensively as the clamping force of the optical fiber, It can be firmly clamped and fixed on the ferrule.

The optical fiber is composed of a fiber core wire formed by covering the fiber element wire with a covering member. The optical fiber is formed in the insertion hole of the inner ferrule with the fiber element wire exposed at the tip. A fiber receiving hole and a core wire receiving hole are formed so as to receive the fiber, and the inner ferrule has a first slit radially passing through the wire receiving hole and a radial direction passing through the core wire receiving hole. It is preferable to form a second slit penetrating through the optical fiber. By doing so, the compressive force at the time of press-fitting is concentrated on the optical fiber element wire in the wire receiving hole and the optical fiber core wire in the core receiving hole. The optical fiber element wire and the core wire can be firmly clamped and fixed together.

[Brief description of drawings]

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

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

FIG. 3 is a side view of an inner ferrule forming the ferrule for an optical connector.

FIG. 4 is a cross-sectional view of an inner ferrule that constitutes the optical connector ferrule.

FIG. 5 is a side view of an optical fiber to which the ferrule for an optical connector is attached.

6 is a cross-sectional view of the inner ferrule taken along arrows AA and BB in FIG.

FIG. 7 is a cross-sectional view of the ferrule for an optical connector with the optical fiber attached.

FIG. 8 is a cross-sectional view showing another example of the inner ferrule.

FIG. 9 is a cross-sectional view showing another example of an optical connector ferrule to which an optical fiber is attached.

FIG. 10 is a plan view (partially sectional view) of a two-core connector housing using the ferrule for an optical connector.

FIG. 11 is a side view of the two-core connector housing.

[Explanation of symbols]

 1, 1'Ferrule for optical connector 2, 2'Outer ferrule 21 Resin outer member 22 Metal tube 3 Inner ferrule 31 Press fitting part 35a Element wire receiving hole 35b Core wire receiving hole 120 Two core connector housing

Claims (3)

[Claims] 1. A light comprising an outer ferrule provided with a through hole extending in a longitudinal direction, and an inner ferrule press-fitted into the through hole by inserting an optical fiber into an insertion hole formed along the central axis. In the ferrule for a connector, the inner ferrule has a slit formed by penetrating in the radial direction through the insertion hole and extending in the axial direction, and the inner ferrule in which the optical fiber is inserted into the insertion hole. When press-fitted into the through-hole of the outer ferrule, the slit-formed portion receives the press-fitting force to sandwich the optical fiber, and at this time, the opposing slit that forms the slit. A ferrule for an optical connector, characterized in that the surfaces thereof are not in contact with each other. 2. The optical fiber is composed of a fiber core wire formed by covering a fiber element wire with a covering member, and an insertion hole of the inner ferrule is a light beam in a state where the fiber element wire is exposed at a tip end portion. A fiber receiving hole and a core wire receiving hole for receiving the fiber. The inner ferrule has a first slit passing through the wire receiving hole in a radial direction and a core wire receiving hole. The ferrule for an optical connector according to claim 1, wherein a second slit penetrating in a radial direction is formed. 3. The inner ferrule is formed in a cylindrical shape, and a cross-sectional shape of a portion of the inner ferrule in which the slit is formed has a pair of fan-shapes which widen with the insertion hole and face each other. The ferrule for an optical connector according to claim 1 or 2, wherein