JP2003248139A - Optical connector, ferrule therefor and method for assembling the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To set bend of an optical fiber to a range in which an influence is not affected to optical characteristics and strength characteristics of the fiber. <P>SOLUTION: A ferrule 1 for an optical connector comprises a plurality of fiber inserting holes 3N<SB>1</SB>to 3N<SB>5</SB>which are disposed at a plurality of stages and in which the optical fibers 2b<SB>1</SB>to 2b<SB>5</SB>are respectively inserted, guide grooves 10N<SB>1</SB>to 10N<SB>5</SB>formed to communicate at one ends with fiber inserting side ends of the holes 3N<SB>1</SB>to 3N<SB>5</SB>and extended along respective fiber inserting hole central axial directions, and a contact 15 formed at a predetermined distance D along the central axial direction of the fiber inserting holes for connecting end faces 5a of the holes 3N<SB>1</SB>to 3N<SB>5</SB>, and with which fiber exposure end ends 2d<SB>1</SB>to 2d<SB>5</SB>of tape-like members 2c<SB>1</SB>to 2c<SB>5</SB>are brought into contact when optical fibers 2b<SB>1</SB>to 2b<SB>5</SB>of the optical fiber tape coated wires 2a<SB>1</SB>to 2a<SB>5</SB>are inserted into the holes 3N<SB>1</SB>to 3N<SB>5</SB>of the respective stages. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ferrule for an optical connector, an optical connector and an optical connector assembling method which are used in a connecting portion between optical fibers in an optical communication, a connecting portion of an optical module such as an optical semiconductor. .

[0002]

2. Description of the Related Art With the development of information networks including optical fiber networks, transmission capacity is rapidly increasing. Therefore,
Higher density is required for the ferrules for optical connectors used in the connection between optical fibers and the connection between optical modules such as optical semiconductors.

In order to achieve the above-mentioned high density, the ferrule for an optical connector has a multi-core structure so that a large number of optical fibers can be collectively connected while maintaining the appearance shape and size of the ferrule to the same extent as the conventional one. It is being advanced.

Particularly, in recent years, a multi-stage multi-stage {1 stage × n-core} ferrule having one multi-core fiber insertion hole (fine hole) for supporting a large number of optical fibers has been pursued for higher density. It has moved to a multi-core (m-stage x n-core) ferrule.

FIG. 9 is a view showing an example of an optical connector ferrule 50 having a multi-core (n-core) fiber insertion hole provided in a multi-stage (m-stage) (m-stage × n-core). That is, in the ferrule for optical connector 50 shown in FIG. 8, for example, n (= 12) core fiber insertion holes 51 arranged in the horizontal direction in the figure are provided in the vertical direction in the figure in m (= 5) stages. It is a 60-core ferrule (5 stages x 12 cores).

In this ferrule for optical connector 50, the optical fiber (bare fiber in this case) at the exposed end of the multi-fiber optical fiber ribbon 52 corresponding to the multi-fiber insertion hole is inserted into the multi-fiber insertion hole. It is fixedly supported via the optical fiber to facilitate connection to an optical connector, an optical module, or the like of a connection partner.

The outer diameter of the optical fiber and the inner diameter of the fiber insertion hole of the ferrule are very small. Therefore, in order to improve the workability of inserting each optical fiber into each fiber insertion hole, the ferrule is provided with a guide groove for guiding the insertion of each optical fiber into each fiber insertion hole.

FIG. 10 shows the ferrule 50 shown in FIG.
It is a longitudinal cross-sectional view at the time of cutting along the step direction, passing through the center of the fiber insertion hole 51. As shown in FIG. 10, in the ferrule 51 for a multi-fiber optical connector, the guide grooves 52 of each step are provided.
Extends in the axial direction from the axially terminating end position of the guide groove 52 one step above.

The ferrule 5 for such a multi-fiber optical connector
When assembling an optical connector using 1, the plurality (5) of multi-core optical fiber tape core wires 53a1 corresponding to the number of stages
Prepare 53a5. Each optical fiber (bare fiber in this case) 5 exposed by peeling off the tape portion of the prepared multi-fiber optical fiber ribbons 53a1 to 53a5 corresponding to the first stage
4a1 to the fiber insertion holes 5 at the bottom (first step)
Insert into 1a1.

At this time, each optical fiber 54a1 is connected to the guide groove of each fiber insertion hole 51a1 of the first stage to which the end (tape peeling end) 53b1 on the optical fiber exposed side of the multi-fiber optical fiber ribbon 53a1 corresponds. It inserts in each said fiber insertion hole 51a1 to the position which contacts 52 (refer FIG. 11).

Next, each stage after the second stage (2 to 5 stages)
For the respective fiber insertion holes 51a2 to 51a5, the multi-core optical fiber tape core wires 53a2 to 53a2 are sequentially arranged toward the upper side.
The optical fibers 54a2 to 54a5 of 53a5 are inserted.

At this time, the optical fibers 54 of two to five stages
a2 to 54a5 are the positions along the fiber hole central axis direction of the optical fiber exposed side end portions (tape peeling end portions) 53b2 to 53b5 of the corresponding multi-fiber optical fiber ribbons 53a2 to 53a5 in the first stage. Corresponding fiber insertion holes 51a2 to 5a so that the positions are the same as the positions of the optical fiber exposed end portions 53b1 along the fiber hole center axis direction.
1a5 (see FIG. 11).

In this way, the optical fibers 54a1 to 54a of the multi-fiber optical fiber ribbons 53a1 to 53a5 are formed.
5 is inserted into each of the fiber insertion holes 51a1 to 51a5, a fiber fixing member such as an adhesive is injected from the window hole 55 to fix each of the optical fibers 54a1 to 54a5 to assemble the optical connector.

[0014]

A multi-core (n-core) fiber insertion hole provided in multiple stages (m stages) is provided (m stages × n).
In the optical connector ferrule 50, the pitch between the holes adjacent in the step direction (hereinafter also referred to as the vertical direction) in the fiber insertion holes 51a1 to 51a5 (the vertical pitch between the central axes of the adjacent holes) is generally 0.25mm
Is. On the other hand, each multi-core optical fiber tape core wire 53a1
The thickness of 53a5 along the vertical direction is generally 0.3 mm.
Is.

Accordingly, the multi-core optical fiber ribbons 53a2 to 53 corresponding to the positions along the step direction of the central axes of the fiber insertion holes 51a2 to 51a5 of the second and subsequent stages.
Between the center position of a5 along the step direction, a vertical shift is generated by the difference between the vertical pitch between the fiber insertion holes and the thickness of the multi-fiber optical fiber ribbon.

Here, the misalignment between the position along the step direction of each fiber insertion hole 51a1 at the bottom (first step) and the position along the step direction of the corresponding multi-fiber optical fiber ribbon 53a1 is It depends on the ferrule internal structure. Therefore, if the above deviation is α, k {1 ≦ k ≦ m from the bottom.
(= 5)} Position along the step direction of the central axis of the fiber insertion hole 51ak at the (third) th step and the multi-fiber optical fiber ribbon 5
Deviation amount Gk from the center position along the step direction of 3 ak
Can be expressed by the following equation (1) using a difference of 0.05 mm between the vertical pitch between the fiber insertion holes and the thickness of the multi-core optical fiber tape.

[0017]

[Formula 1]

As can be seen from the above equation (1), the larger the number of steps k, the larger the deviation Gk. As described above, the amount of deviation G between the position along the step direction of the central axis of the fiber insertion hole of each of the second and subsequent stages and the center position of the multi-fiber optical fiber ribbon 53 ak along the step direction
k is generated, the fiber insertion hole 51a1 at each stage
To 51a5, each multi-core optical fiber tape core wire 53a1-5
When the optical fibers 54a1 to 54a5 of 3a5 are inserted, as shown in FIG. 11, the optical fibers 54a2 to 54a5 corresponding to the second and subsequent stages are particularly bent. That is, the optical fibers 54a2 to 54a5 corresponding to the second and subsequent stages are fixed in a bent state.

The bending of the optical fiber (bare fiber) may increase the connection loss in terms of optical characteristics. From the viewpoint of strength characteristics, it is also conceivable that when the bent portion is deformed due to expansion and contraction in the ferrule due to temperature change, moisture absorption, etc., the bare fiber may be broken.

The present invention has been made in view of the above circumstances, and it is possible to set the bending of an optical fiber (bare fiber) within a range that does not affect the optical characteristics and strength characteristics of the optical fiber. An object of the present invention is to provide a ferrule for an optical connector, an optical connector and an optical connector assembling method capable of preventing deterioration of optical characteristics and strength characteristics of the entire ferrule and the entire optical connector due to the fiber bending.

[0021]

[Means for Solving the Problems]

According to a first aspect of the present invention for achieving the above-mentioned object, there is provided a ferrule for an optical connector for supporting an optical fiber tape core wire having an end coating removed and an optical fiber exposed. A plurality of fiber insertion holes, which are arranged in a plurality of steps and into which the optical fibers are inserted, are formed so that one end portion communicates with the fiber insertion side end portion of each fiber insertion hole. A guide portion for an optical fiber insertion guide extending along the central axis direction of the fiber insertion hole, and an opening side end portion of each of the fiber insertion holes opposite to the fiber insertion side end portion of the fiber insertion hole from the central axis direction of the fiber insertion hole. Are formed at a predetermined distance along each other, and when each optical fiber of the optical fiber tape core is inserted into each fiber insertion hole of each step, the tape-shaped portion of the optical fiber tape core Fiber exposed end of the is provided with a abutment portion abutting.

In the first aspect of the present invention, a predetermined distance along the central axis direction of the fiber insertion hole from the opening side end of each fiber insertion hole to the abutting portion is set to be equal to each fiber of each stage. Curvature radii r1 to rm of the bend of each optical fiber in each step when each optical fiber of the optical fiber ribbon is inserted into the insertion hole (where m is an integer of 2 or more and corresponds to the number of steps). ) Is set to be a predetermined value or more.

According to the second aspect of the present invention for achieving the above-mentioned object, the optical fiber tape core wire from which the coating of the end portion is removed and the optical fiber is exposed, and the optical fiber tape core wire supporting member A ferrule, wherein the ferrule is arranged in a plurality of steps, a plurality of fiber insertion holes into which the optical fibers are inserted, and one end of the ferrule communicates with a fiber insertion side end of each of the fiber insertion holes. And a guide portion for an optical fiber insertion guide extending along the central axis direction of each fiber insertion hole, and an opening side end portion of the fiber insertion hole opposite to the fiber insertion side end portion. From the fiber insertion hole is formed at a predetermined distance along the central axis direction, when each optical fiber of the optical fiber tape core wire is inserted into each fiber insertion hole of each stage, Fiber exposed end of the tape-like member of fiber ribbons are provided with abutment portion abutting.

According to a third aspect of the present invention for achieving the above-mentioned object, an optical connector assembling method for assembling an optical connector by using an optical fiber ribbon which has an end coating removed to expose an optical fiber. The plurality of fiber insertion holes, which are arranged in a plurality of steps, are formed so that one end portion communicates with the fiber insertion side end portion of each of the fiber insertion holes. , A guide portion for an optical fiber insertion guide extending along the central axis direction of each fiber insertion hole and the center of the fiber insertion hole from the opening side end of the fiber insertion hole opposite to the fiber insertion side end A step of preparing ferrules each having an abutting portion formed at a predetermined distance along the axial direction, and each of the optical fiber ribbons in each fiber insertion hole of each step Fiber, and a step of fiber exposed end of the tape-like member of the optical fiber ribbon is inserted to a position abutting the abutting portion.

[0026]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic configuration of an optical connector ferrule (hereinafter, simply referred to as a ferrule) 1 which constitutes an optical connector C according to an embodiment of the present invention, and is inserted and fixedly supported in the ferrule 1. It is a perspective view respectively showing a plurality (five in this embodiment) of optical fiber tape cable cores 2a1-2a5.

FIG. 2 shows the ferrule 1 shown in FIG.
Through the center of the fiber insertion hole 3 in the step direction (height direction)
FIG. 4 is a vertical cross-sectional view when cut along the line, and is a vertical cross-sectional view taken along the line II-II shown in FIG. 3 below.

As shown in FIGS. 1 and 2, the ferrule 1 has a rectangular shape and is integrally formed by molding a plastic material resin, for example.

That is, the ferrule 1 has a plurality of (a plurality of cores; in this embodiment, 12 cores) fiber insertion holes 3 along the longitudinal direction thereof. The plurality of fiber insertion holes 3 are arranged in a plurality of stages (the first stage to the fifth stage in the present embodiment) along the ferrule height direction. In addition, the plurality of fiber insertion holes 3 in each stage are juxtaposed with each other at a constant interval (pitch) along the short-side direction of the ferrule 1, and the intervals between the fiber insertion holes 3 along the step direction ( The pitch) is also constant.

Hereinafter, in this embodiment, the 12-core fiber insertion hole 3 of the first-stage fiber insertion hole 3 is 3N1, and similarly, the plurality of second- to fifth-stage fiber insertion holes 3 are formed.
Is also referred to as 3N2 to 3N5.

Optical fiber tape core wires 2a1 to 2a5
Is a plurality (12 cores) of optical fibers corresponding to a plurality (12 cores) of fiber insertion holes 3 in each stage, as shown in FIG.
The tape-shaped members 2c1 to 2c5 for covering the plurality of optical fibers in a tape shape are provided.

At the end of the optical fiber ribbon core wire 2a1 corresponding to the first stage, the tape-shaped member 2c1 at that end is removed and the 12-fiber optical fiber (bare fiber in this case) 2b1 is exposed. There is. Similarly, the second stage ~
At the ends of the fifth-stage optical fiber ribbons 2a2 to 2a5, 12 optical fibers 2b2 to 2b5 are exposed.

The diameter of each of the fiber insertion holes 3N1 to 3N5 is substantially equal to the diameter of the corresponding optical fiber 2b1 to 2b5 so that the corresponding optical fiber 2b1 to 2b5 can be inserted.

Further, the ferrule 1 is provided with a first housing portion 5 having an opening surface including the end portions on the opening side of the plurality of fiber insertion holes 3 arranged in a plurality of stages. The opening surface serves as a connection end surface 5a for connecting to another optical component such as an optical connector or an optical module. In addition, the ferrule 1 has a second housing portion 6 extending from the first housing portion 5 along the fiber insertion hole center axis direction.
Is equipped with.

The second housing portion 6 has an upper surface 7 which is connected from the end portion of the connection end surface 5a of the first housing portion 5 along the step direction along the axial direction of the fiber hole. Is formed with a window hole 8 for injecting a member (for example, an adhesive) for fixing the optical fiber when the optical fiber of the optical fiber ribbon 2 is inserted into the fiber insertion hole 3 of each stage.

The ferrule 1 has the same structure as that shown in FIGS.
, The fiber insertion holes 3N1 to 3N5 of each stage
One end portion is formed so as to communicate with the lower half peripheral edge portion of the lower half, and guide grooves 10N1 to 1N1 for optical fiber insertion guide extending coaxially along the central axis direction of the fiber insertion hole.
It is equipped with 0N5.

First to fifth stage fiber insertion holes 3N1 to 3N1
3N5 extends to an end position on the opposite side of the guide groove of the adjacent upper-stage fiber insertion hole from the optical fiber insertion direction, and as a result, the first to fifth-stage guide grooves 10N1.
-10N5 and the entire fiber insertion holes 3N1 to 3N5 have a stepwise shape that widens from the upper stage to the lower stage in the cross-sectional view shown in FIG. Therefore, the positions of the optical fiber insertion side end portions of the fiber insertion holes 3N1 to 3N5 of the respective stages are gradually separated from the connection end surface 5a from the upper stage to the lower stage.

FIG. 3 shows the ferrule 1 shown in FIG. 2 with guide grooves 10N3 corresponding to the third-stage fiber insertion hole 3N3.
FIG. 3 is a lateral cross-sectional view taken along the line III-III when cut along the upper end surface of the peripheral edge portion of FIG.

As shown in FIGS. 2 and 3, the second housing portion 6 has an insertion opening 12 for inserting the optical fiber ribbon core wire 2 facing the opening surface 5a of the first housing portion 5, It is provided with a flange portion 13 formed on the outer peripheral portion of this insertion port 12 forming portion.

As shown in FIGS. 2 and 3, the second housing portion 6 has an abutting portion 15 formed at a predetermined distance D from the connecting end surface 5a along the central axis direction of the fiber insertion hole. I have it.

As shown in FIG. 3, the abutting portion 15 is formed as projecting portions 15a and 15b projecting from the inner peripheral edge portions 6a and 6b of the second housing portion 6 facing each other in a stepwise manner in the facing direction. Has been done.

The distance D10 between the protrusion 15a and the protrusion 15b is shorter than the lateral width W10 of the fiber exposed side end portions (end surfaces) 2d1 to 2d5 of the tape-shaped members 2c1 to 2c5 of the optical fiber ribbons 2a1 to 2a5. It has become a length.

Further, the distance D10 between the protrusion 15a and the protrusion 15b is determined by the optical fiber ribbons 2a1 to 2a.
No. 5 optical fibers 2b1 to 2b5 are prevented from interfering with the insertion of the optical fibers 2b1 to 2b5.
It is longer than the lateral width (hereinafter referred to as the optical fiber width) W11 between the optical fibers 2b1 and b5 at both ends of 2a5.

The contact portion 15 has optical fiber ribbons 2a1 to 2a5 in the fiber insertion holes 3N1 to 3N5 at the respective stages.
When each of the optical fibers 2b1 to 2b5 is inserted, the tape-shaped member 2c1 of the optical fiber ribbons 2a1 to 2a5
2c1 to 2c5 on the fiber exposed side end (end face)
It is formed at a position where 2d5 abuts.

Further, the ferrule 1 has a fiber insertion hole 3N1 including the stepwise guide grooves 10N1 to 10N5.
˜3N5 and the insertion port 8 and the optical fiber 2 inserted into the fiber insertion holes 3N1 to 3N5 of each stage.
An accommodating portion 16 for accommodating b1 to 2b5 is provided.

Further, the ferrule 1 is arranged in parallel with the insertion hole on both sides of the fiber insertion hole 3 in the parallel direction, and has two guide pin holes 17a1 for inserting guide pins for alignment. , 17a2.

The fiber tape core wire 2a1 corresponding to the first stage is inserted into the accommodating portion 16 through the insertion port 12 of the ferrule 1 thus constructed.

Then, the optical fiber 2b1 of the optical fiber ribbon 2a1 is inserted into the corresponding first-stage fiber insertion hole 3N1 along the guide groove 10N1.

At this time, each optical fiber 2b1 of the optical fiber ribbon 2a1 is in the corresponding fiber insertion hole 3N1 up to the position where the fiber exposed side end 2d1 of the tape-shaped member 2c1 abuts the abutting portion 15. And is supported by the respective fiber insertion holes 3N1.

Fiber insertion hole 3N of the fiber 2b1
The protrusion 1 which is the abutting portion 15 when it is inserted into
Since the distance D10 between the 5a and the protruding portion 15b is shorter than the lateral width W10 of the fiber exposed side end portions (end surfaces) 2d1 to 2d5, the tape-shaped member 2 of the optical fiber tape core wire 2a1.
The fiber-exposed-side end portion 2d1 of c1 has a contact portion 15
And is fixed in the contact state.

Hereinafter, the optical fiber ribbons 2a2 to 2a5 of the second to fifth stages are inserted into the accommodating portion 16 in ascending order from the second stage, and the optical fiber ribbons 2a2 to 2a2 are inserted.
2a5 optical fibers 2b2 to 2b5 to the guide groove 10N
It inserts in the 2nd-5th corresponding fiber insertion hole 3N2-3N5 along 2-10N5.

At this time, similarly to the first stage, the optical fibers 2b2 to 2b5 of the optical fiber ribbons 2a2 to 2a5.
Are respectively inserted into the corresponding fiber insertion holes 3N2 to 3N5 up to the positions where the fiber exposed side ends 2d2 to 2d5 of the tape-shaped members 2c2 to 2c5 abut the abutting portion 15, and the respective fiber insertion holes 3N2. ~ 3N5
Supported by. Also, the optical fiber ribbons 2a2-2
The fiber-exposed-side end portions 2d2 to 2d5 of the tape-shaped members 2c2 to 2c5 of a5 are fixed in contact with the contact portion 15.

FIG. 4 shows the ferrule 1 in which the optical fibers 2b1 to 2b5 of the optical fiber ribbons 2a1 to 2a5 are inserted into the first to fifth stage fiber insertion holes 3N1 to 3N5 of the ferrule 1. It is a longitudinal cross-sectional view corresponding to FIG. 2 when the optical fiber ribbons 2a1 to 2a5 are cut along the step direction (height direction) through the centers of the fiber insertion holes 3N1 to 3N5.

Further, FIG. 5 shows the ferrule 1 with the optical fibers 2b1 to 2b5 of the optical fiber ribbons 2a1 to 2a5 shown in FIG. 4 being inserted into the guide groove corresponding to the fiber insertion hole 3N3 of the third stage. It is a VV arrow cross-sectional view at the time of cutting along the peripheral end upper end surface of 10N3.

As shown in FIGS. 4 and 5, all the optical fibers 2b1 to 2a5 of the optical fiber ribbons 2a1 to 2a5.
In 2b5, the fiber exposed side end portions 2d1 to 2d5 of the tape-shaped members 2c1 to 2c5 are brought into contact with the contact portion 15.
It will be inserted up to the fixed position.

As described above, while the optical fibers 2b1 to 2b5 are inserted and supported in the fiber insertion holes 3N1 to 3N5, the adhesive is injected into the ferrule 1 through the window hole 8 to form the optical fibers 2b1 to 2b5. By fixing, the optical connector C is created.

Next, the operation based on the configurations of the ferrule 1 and the connector C of this embodiment will be described.

FIG. 6 shows the conventional optical fibers 54a1 to 5 of the multi-fiber optical fiber ribbons 53a1 to 53a3 in the first to third fiber insertion holes 51a1 to 51a3.
Optical fibers 54a2 and 5 with 4a3 inserted
It is a figure which shows the bending of 4a3.

That is, the bending of the optical fiber 54ak at the k-th stage (k is an integer of 1 or more) is the optical fiber 54a.
It can be expressed as a radius of curvature r of k. The radius of curvature r of the optical fiber 54ak is between the peeling end portion (end portion of the optical fiber exposed side) 53bk of the k-th optical fiber tape core wire 53ak and the corresponding guide groove 52 of the fiber insertion hole 51ak. And the deviation amount Gk between the position along the step direction of the central axis of the fiber insertion hole 51ak at the k-th step and the center position of the multi-fiber optical fiber ribbon 53ak along the step direction. Can be expressed as

Next, a method of approximating the curvature radius r of the bend will be described.

As shown in FIG. 7, the trajectory of an optical fiber fixed in a state where both ends (fixed point a) are displaced (positional deviation amount: G corresponding to the above deviation amount Gk) is first fixed point a. A sin curve is approximated in an xy coordinate system with the origin as. That is, in the trajectory of the optical fiber shown in FIG. 7, when the distance between the fixed points is D (corresponding to the distance Dk ′), the wavelength of the cos function (y = cos x) with the fixed point a as the origin is 2D. It can be approximated as an inverted curve.

That is,

[Formula 2]

If the origin of equation (2) is adjusted to a fixed point,
Expression (2) can be expressed as the following expression.

[Formula 3]

As shown in FIG. 7, since the amplitude corresponds to G, the locus of the optical fiber finally becomes

[Formula 4] Can be expressed as

Further, the radius of curvature r at the point x of the locus represented by the xy coordinate system can be represented by the following equation (5).

[Formula 5]

Since the radius of curvature is minimum at both ends (that is, the bend is maximum), the equation (4) is second-order differentiated and substituted into the equation (5), and further x = 0 is substituted into the equation (5). By calculating, the following equation (6) is derived.

[0068]

[Formula 6]

That is, since the bending amount of the optical fiber is inversely proportional to the radius of curvature r, as can be seen from the equation (6), if the distance D is long, the radius of curvature r can be increased and the bending can be reduced.

In this respect, in the conventional ferrule 50, as shown in FIG. 6, each optical fiber 54a1 of the first-stage optical fiber ribbon 53a1 is connected to each fiber corresponding to the optical fiber exposed end 53b1. Insertion hole 51a1
Each of the optical fibers 54a of two to five stages is inserted into each of the fiber insertion holes 51a1 to a position where the optical fiber 54a abuts the guide groove 52 of
2 to 54a5 to the corresponding optical fiber exposed side end portion 53b
Corresponding fiber insertion holes 51a2 so that the positions along the fiber hole center axis of 2 to 53b5 are the same as the positions along the fiber hole center axis of the first-stage optical fiber exposed end 53b1. Inserted into ~ 51a5.

Therefore, in the second and subsequent stages (k ≧ 2), the distance Dk ′ between the optical fiber exposed end 53bk of the kth optical fiber ribbon 53ak and the guide groove 52 of the fiber insertion hole 51ak. Can be expressed as the following equation (7), where L is the length of the corresponding k-th guide groove 52 in the direction of the fiber hole center axis.

[Formula 7]

That is, the distance Dk 'corresponds to the corresponding k
The length of the guide groove 52 of the step in the direction of the central axis of the fiber hole is L
Is very short and has a large bend (distortion)
Will occur.

Using the conventional ferrule 50, the optical fibers 2b1-2b5 of the optical fiber ribbons 2a1-2a5.
In the optical connector C which is assembled by inserting and fixing the above, a large bend (distortion) is generated in the optical fibers 2b2 to 2b5 of the second and subsequent stages.

However, in the structure of this embodiment, as shown in FIGS. 4, 5 and 8, the guide groove 1
0N1 to 10N5 are formed at a predetermined distance Dk (D1 to D5) from the other end E1 to E5 on the side opposite to the fiber insertion hole along the central axis direction of the fiber insertion holes 3N1 to 3N5 of each stage. A contact portion 15 is provided. Therefore, when the optical fibers 2b1 to 2b5 of the optical fiber ribbons 2a1 to 2a5 are inserted into the fiber insertion holes 3N1 to 3N5 of the respective stages, the tape-shaped members 2c1 to 2c5 of the optical fiber ribbons 2a1 to 2a5 are inserted. The end portions (end surfaces) 2d1 to 2d5 of the fiber on the fiber exposure side are brought into contact with the contact portion 15 and fixed.

That is, in the configuration of this embodiment,
The distance Dk between the optical fiber exposed end 2dk of the k-th fiber tape core wire 2ak and the other end Ek of the guide groove 10Nk of the corresponding fiber insertion hole 3Nk is determined by the contact portion 15
Position of the fiber insertion hole along the central axis direction, in other words, the distance D from the other end Ek of the guide groove 10Nk of the contact portion 15 along the central axis direction of the fiber insertion hole 3Nk.
It can be represented as k (D1 to D5).

Therefore, the optical fiber exposed end 2dk of the k-th stage fiber tape core wire 2ak corresponding to the distance of the contact portion 15 and the other end Ek of the guide groove 10Nk of the fiber insertion hole 3Nk corresponding thereto. If the distance Dk between them is set sufficiently long and the radius of curvature r of each of the optical fibers 2b1 to 2b5 is increased, the bending (distortion) generated in each of the optical fibers 2b1 to 2b5 can be suppressed to a minimum.

It is generally known that the bends generated in the optical fibers 2b1 to 2b5 do not affect the optical characteristics and the strength characteristics of the optical fibers as long as the radius of curvature r is 30 mm or more.

Therefore, in the present embodiment, the optical fiber exposed side end portion 2dk of the k-th stage fiber tape core wire 2ak.
The distance Dk between the corresponding fiber insertion hole 3Nk and the other end Ek of the guide groove 10Nk.
The radius of curvature r of 2b5 is set to 30 mm or more.

For example, in the present embodiment, k (1 ≦ k
≦ 5) The amount of fiber position deviation Gk in the step is calculated by using the difference (0.05) between the fiber pitch in the step direction and the thickness of the tape-shaped member in the above equation (1) {Gk = 0.05 (k−1) + α. } Can be represented. Then, the guide grooves 10N1 to 10 of each step
The length of the N5 along the central axis direction of the fiber insertion hole is L =
0.3 (mm), using the above formula (6), r ≧ 30
When the distance Dk that is equal to or greater than mm is obtained, the results shown in Table 1 are obtained.

[0080]

[Table 1]

Here, in the ferrule 1 of this embodiment, the distance from the connection end surface 5a to the other end E5 of the fifth-stage guide groove 10N5 along the central axis direction of the fiber insertion hole is 2.0 (mm). Then, the distance from the connection end face 5a to the other end E4 of the fourth-stage guide groove 10N4 along the fiber insertion hole center axis direction is 2.3 (mm), and the connection end face 5a extends along the fiber insertion hole center axis direction. The distance to the other end E3 of the third-stage guide groove 10N3 is 2.6 (mm), and from the connection end surface 5a to the other end E2 of the second-stage guide groove 10N2 along the fiber insertion hole center axis direction. Is 2.9
(Mm), the distance from the connection end surface 5a to the other end E1 of the first-stage guide groove 10N1 along the fiber insertion hole center axis direction is 3.2 (mm).

Therefore, the ferrule end faces 5a of the respective stages (1st to 5th stages) and the optical fiber exposed end portions 2d1 to 2d of the first to fifth stage fiber tape core wires 2a1 to 2a5.
The distances Ds1 to Ds5 from No. 5 are obtained as shown in Table 2 below.

[Table 2]

That is, the distance Ds1 from the ferrule end surface 5a to the optical fiber exposed side end portions 2d1 to 2d5 of the first to fifth stage fiber tape core wires 2a1 to 2a5.
Ds5 is the value Ds1 = 3.
If it is set to 20 (mm) to Ds5 = 7.44 (mm), the radius of curvature r of the bend of the optical fibers 2b1 to 2b5 ≧
It becomes possible to make it 30 mm or more.

However, it is difficult to individually set the distances Ds1 to Ds5 of the optical fiber exposed side end portions 2d1 to 2d5 of the first to fifth stage fiber tape cores 2a1 to 2a5 for each step. is there.

Therefore, in this embodiment, the first to fifth stages are used.
Among the distances Ds1 to Ds5 of the optical fiber exposed side ends 2d1 to 2d5 of the fiber tape cores 2a1 to 2a5 of the step, the distance Ds5 of the longest step (fifth step) is set to each step (1 step to 5 steps). ) Is set as a common distance between the ferrule end surface 5a and the optical fiber exposed end portions 2d1 to 2d5 of the first to fifth stage fiber tape core wires 2a1 to 2a5.

That is, the distance D between the connection end surface 5a and the contact portion 15 along the central axis direction of the fiber insertion hole is set to Ds5 = 7.44 (mm).

As a result, in this embodiment, the tape-shaped members 2c1 to 2c5 of all the fiber tapes 2a1 to 2a5.
The fiber exposed side end portions 2d1 to 2d5 in the contact portion 1
Since it is abutted and fixed to No. 5, the above-mentioned fiber exposed side end portions (peeling end portions) 2d1 to 2d5 should be fixed at positions where the corresponding optical fibers 2b1 to 2b5 have a radius of curvature r of 30 mm or more. You can

Therefore, each of the optical fibers 2b1 to 2b5
Of the optical fibers 2b1 to 2b5 can be suppressed to the minimum extent that does not affect the optical characteristics and strength characteristics of the optical fibers 2b1 to 2b5.

As a result, deterioration of optical characteristics and strength characteristics due to the bending of the optical fibers 2b1 to 2b5 due to the influence of molding distortion, temperature change, distortion due to moisture absorption, etc. is suppressed, and the reliability of the entire ferrule 1 and the optical connector C is reduced. It is possible to maintain high sex.

It should be noted that the distance D = between the above-mentioned connection end surface 5a and the contact portion 15 along the fiber insertion hole center axis direction.
7.44 (mm) is merely a specific example, and it goes without saying that the numerical value itself is not limited.

Further, in this embodiment, each optical fiber 2b is
The reliability allowable range of the curvature radius r of the bends 1 to 2b5 is set to 30 mm or more, and the distance D between the connection end surface 5a and the abutting portion 15 along the central axis direction of the fiber insertion hole is set to Although it is set to be 30 mm or more, the present invention is not limited to this.

That is, even if the radius of curvature r is allowed to be less than 30 mm for the reason that the ferrule itself is downsized while sacrificing reliability to some extent, the connection end surface 5a and the fiber should satisfy the radius of curvature r. The distance D between the contact portion 15 and the axial direction of the insertion hole may be set.

Further, in the present embodiment, the 60-core ferrule in which the 12-fiber insertion holes are arranged in the first to fifth stages and the optical connector using the 60-core ferrule have been described. Is not limited to this, and may be a ferrule having a plurality of fiber insertion holes arranged in a plurality of stages and an optical connector using this ferrule.

[0094]

As described above, according to the ferrule for an optical connector, the optical connector and the optical connector assembling method according to the present invention, the opening side end of each fiber insertion hole opposite to the fiber insertion side end. From the optical fiber at a predetermined distance along the central axis direction of the fiber insertion hole, and when each optical fiber at the end of the tape optical fiber is inserted into each fiber insertion hole of each stage, Since the abutting portion with which the fiber exposed side end of the member abuts is provided, the predetermined distance of the abutting portion is set to a value that does not affect the bending of each optical fiber (curvature radius of curvature is 30 mm or more). can do.

Therefore, the bending of each optical fiber can be suppressed to the minimum extent that does not affect the optical characteristics and strength characteristics of each optical fiber. As a result, it is possible to suppress the deterioration of the optical characteristics and the strength characteristics due to the bending of the optical fiber, and maintain the reliability of the entire ferrule and the entire optical connector high.

[Brief description of drawings]

FIG. 1 shows a schematic configuration of an optical connector ferrule that constitutes an optical connector according to an embodiment of the present invention and a schematic configuration of a plurality of optical fiber ribbons that are fixedly supported by being inserted into the ferrule. Perspective view.

2 is a vertical sectional view of the ferrule shown in FIG. 1 cut along the step direction (height direction) passing through the center of the fiber insertion hole, and is a vertical sectional view taken along the line II-II shown in FIG. .

FIG. 3 is a lateral cross-sectional view taken along the line III-III when the ferrule shown in FIG. 2 is cut along the upper end surface of the peripheral edge portion of the guide groove corresponding to the third-stage fiber insertion hole.

FIG. 4 shows a ferrule and an optical fiber tape core wire in a state where an optical fiber of the optical fiber tape core wire is inserted into the fiber insertion holes of the first to fifth steps of the ferrule and is passed through the center of the fiber insertion hole. FIG. 3 is a vertical cross-sectional view corresponding to FIG. 2 when cut along the step direction (height direction).

5 is a V when the ferrule with the optical fiber of the optical fiber ribbon shown in FIG. 4 inserted therein is cut along the upper end surface of the peripheral edge of the guide groove corresponding to the third-stage fiber insertion hole; -V arrow cross-sectional view.

FIG. 6 is an enlarged view showing an optical fiber and its bending in a state in which each optical fiber of each multi-core optical fiber ribbon is inserted into the conventional first to third stage fiber insertion holes.

FIG. 7 is a diagram showing a trajectory of an optical fiber whose both ends are positionally fixed.

FIG. 8 is an enlarged view showing an optical fiber and its bending in a state in which each optical fiber of each multi-core optical fiber ribbon is inserted into the fiber insertion holes of the first to third stages of the present embodiment. Fig.

FIG. 9 is a perspective view showing a schematic configuration of a conventional ferrule for an optical connector.

FIG. 10 is a vertical cross-sectional view of the ferrule shown in FIG. 9 cut along the step direction through the center of the fiber insertion hole.

11 is a longitudinal sectional view showing a state in which an optical fiber of a fiber tape is inserted into the ferrule shown in FIG.

[Explanation of symbols]

1 ferrule 2a1-2a5 optical fiber tape 2b1-2b5 optical fiber (bare fiber) 2c1 to 2c5 tape-shaped member 2d1 to 2d5 Fiber exposed side end 3, 3N1-3N5 Fiber insertion hole 5 First housing part 5a Connection end face 6 Second housing part 7 Upper surface 8 window holes 10N1-10N5 guide groove 12 insertion slot 13 Flange 15 Contact part 15a, 15b protrusion 16 Housing

Claims (9)

[Claims] 1. A ferrule for an optical connector for supporting an optical fiber tape core wire from which an optical fiber is exposed by removing an end coating, and a plurality of ferrules arranged in a plurality of steps and into which the optical fiber is inserted. A fiber insertion hole, and one end portion is formed so as to communicate with the fiber insertion side end portion of each fiber insertion hole, for an optical fiber insertion guide extending along the central axis direction of each fiber insertion hole A guide portion and a fiber insertion side end of each fiber insertion hole are formed at a predetermined distance along the central axis direction of the fiber insertion hole from the opening side end opposite to the fiber insertion side end of each of the steps. An abutting portion with which the fiber exposed side end of the tape-shaped member of the optical fiber tape core abuts when each optical fiber of the optical fiber tape core wire is inserted into each fiber insertion hole. Ferrule for optical connector. 2. A predetermined distance along the central axis direction of the fiber insertion hole from the opening side end of each fiber insertion hole to the abutting portion is set in each of the fiber insertion holes of each stage by the optical fiber tape. When each optical fiber of the core wire is inserted, the radius of curvature r1 of the bend of each optical fiber in each stage concerned
The ferrule for an optical connector according to claim 1, wherein rm (where m is an integer of 2 or more and corresponds to the number of stages) is set to be a predetermined value or more. 3. The ferrule for an optical connector according to claim 2, wherein the predetermined value is 30 mm. 4. A first housing part having the plurality of fiber insertion holes formed therein and having an opening surface including the end portions on the opening side of the plurality of fiber insertion holes, and the fiber from the first housing part. A second housing part that extends along the insertion hole central axis direction and that includes an insertion port for inserting the optical fiber tape core wire that faces the opening surface; The ferrule for an optical connector according to any one of claims 1 to 3, wherein the ferrules for the optical connector are projecting portions that respectively project in a stepwise manner in the facing direction from inner peripheral edge portions of the insertion opening of the second housing portion that face each other. . 5. The distance between the projecting portions projecting from the inner peripheral edge portions of the insertion openings facing each other is shorter than the lateral width of the fiber exposed side end portion of the tape-shaped member of the optical fiber ribbon. The ferrule for an optical connector according to claim 4, wherein 6. An optical connector, comprising: an optical fiber tape core wire from which an end coating is removed to expose an optical fiber; and a ferrule for supporting the optical fiber tape core wire, wherein the ferrule comprises a plurality of ferrules. A plurality of fiber insertion holes, which are arranged stepwise, into which the optical fibers are inserted, are formed so that one end portion communicates with the fiber insertion side end portion of each fiber insertion hole. A guide portion for an optical fiber insertion guide extending along the central axis direction of the hole, and along the central axis direction of the fiber insertion hole from the opening side end opposite to the fiber insertion side end of each fiber insertion hole. Are formed at a predetermined distance from each other, and when each optical fiber of the optical fiber tape core wire is inserted into each fiber insertion hole of each step, the tape-shaped portion of the optical fiber tape core wire Optical connector, characterized in that the fibers exposed end of equipped with, abutment portion abutting. 7. An optical connector assembling method for assembling an optical connector using an optical fiber tape core wire having an end coating removed to expose an optical fiber, wherein the optical fiber is arranged in a plurality of steps and the optical fibers are inserted. A plurality of fiber insertion holes, one end of which is connected to the fiber insertion side end of each fiber insertion hole, and an optical fiber insertion extending along the central axis direction of each fiber insertion hole. A guide portion for guiding and an abutting portion formed at a predetermined distance along the central axis direction of the fiber insertion hole from the opening side end opposite to the fiber insertion side end of each fiber insertion hole. Preparing a ferrule having each, each optical fiber of the optical fiber tape core wire in each fiber insertion hole of each stage, the tape-shaped member of the optical fiber tape core wire An optical connector assembling method characterized by Aiba exposed end portion is provided with, and inserting to a position abutting the abutting portion. 8. A predetermined distance along the central axis direction of the fiber insertion hole from the opening-side end of each fiber insertion hole to the abutting portion is set in each of the fiber insertion holes of each stage by the optical fiber tape. When each optical fiber of the core wire is inserted, the radius of curvature r1 of the bend of each optical fiber in each stage concerned
8. The method for assembling an optical connector according to claim 7, wherein rm (where m is an integer of 2 or more and corresponds to the number of steps) is set to be a predetermined value or more. 9. The method of assembling an optical connector according to claim 8, wherein the predetermined value is 30 mm.