JP2003029087A - Multi-fiber and multi-stage ferrule - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multi-fiber and multi-stage ferrule which can be molded with high precision without bending a fiber hole. SOLUTION: The ferrule 10 has pin holes into which guide pins are inserted, a plurality of fiber holes 10f which are formed between the pin holes and into which optical fibers are inserted, an opening 10d which communicates with the fiber holes and into which an adhesive is injected, and a lead-in hole 10c which communicates with the plurality of fiber holes 10f and the opening 10d and is opened in a rear-end surface Fr and into which an optical fiber is inserted. The plurality of fiber holes 10f are so formed in stages that end parts which are open to lead-in openings 10c of 2nd and succeeding stages from below when the openings 10d are viewed from above are positioned within a range of the openings 10d or a guide groove for guiding an optical fiber to a fiber hole is connected to the end part of the fiber hole and the end part of the guide groove is positioned within the range of the openings.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-core multi-stage ferrule in which a plurality of fiber holes per stage are formed by superposing a plurality of stages.

[0002]

2. Description of the Related Art In an optical connector used in optical communication,
Development of plastic ferrules is underway for the purpose of increasing the number of cores of optical fibers, increasing the density, improving the accuracy of butt connection, and lowering the cost due to the mass productivity of optical connectors. As such a plastic ferrule, a multi-core multi-stage ferrule used in an m-core × n-stage optical connector in which n optical fibers are stacked per stage, for example, the ferrule 1 shown in FIGS. A collar portion 1b is formed at the rear portion of 1a, and an introduction port 1c that extends in the front-rear direction and that opens to the rear end face Fr of the collar portion 1b is formed at approximately the center. The ferrule 1 communicates with the inlet 1c on the upper surface of the main body 1a and is an opening 1 called an injection window for injecting an adhesive.
d is formed. In addition, ferrule 1 is on both sides,
Two pin holes 1 for inserting the guide pins along the longitudinal direction
e is formed, and between the two pin holes 1e at the front part of the main body 1a, eight fiber holes 1f for each step through which the optical fiber is inserted are formed in a staggered manner with three steps vertically. At this time, a guide groove 1g for guiding the optical fiber is provided in the fiber hole 1f at each stage, as shown in FIG.

Therefore, the ferrule 1 is guided by the guide groove 1g formed by shifting in a stepwise manner and each optical fiber is inserted into the fiber hole 1f to be assembled into an optical connector.

[0004]

By the way, when the fiber hole 1f is formed stepwise as described above, the ferrule 1
The fiber hole 1f becomes longer as it goes down. Along with this, in the ferrule 1, the core pin forming the fiber hole 1f becomes long, and the core pin, and hence the molded fiber hole, may be bent by the resin pressure during molding.

Further, since the ferrule 1 inserts the optical fiber into the fiber hole 1f while visually checking it from the opening 1d,
As the number of steps of the fiber hole 1f increases, the opening 1d needs to be formed larger. However, if the opening 1d is enlarged,
In the ferrule 1, depending on the presence or absence of molding resin on the side of the opening 1d and on the side opposite to the opening 1d, the balance of resin shrinkage after molding becomes poor, and the positional accuracy of the fiber hole 1f and the pin hole 1e deteriorates.

On the other hand, in order to prevent bending of the core pin due to molding, it is conceivable to shorten the core pin, that is, to move the opening 1d toward the front end face Ff of the ferrule to shorten the fiber hole 1f. However, ferrule 1
With this design, the optical fiber F is inserted in the fiber hole 1f.
When op is bonded and fixed with an adhesive and assembled into an optical connector, the front end face Ff where the opening 1d is located due to the difference in linear expansion coefficient between the synthetic resin forming the ferrule 1 and the adhesive Ad.
On the side, it is conceivable that a warp will occur as shown in FIG. When such a warp occurs, there is a problem that the connection loss increases in the optical connector using the ferrule 1.

The present invention has been made in view of the above points, and it is an object of the present invention to provide a multi-core multi-stage ferrule that can be molded with high accuracy without bending the fiber hole.

[0008]

In order to achieve the above object, the present invention has a pin hole through which a guide pin is inserted,
A plurality of fiber holes that are formed between the pin holes and through which the optical fiber is inserted, an opening that communicates with the plurality of fiber holes, and in which an adhesive is injected, and a plurality of the plurality of fiber holes that extend in the front-rear direction approximately at the center. A ferrule in which a fiber hole and an opening which communicates with the opening and opens to a rear end surface and which is provided with an introduction port for introducing the optical fiber is formed, and the plurality of fiber holes are formed in a plurality of stages, and the plurality of stages are formed. As for the fiber hole, when the opening is viewed upward, the end portion of the second or more stages from the bottom that opens to the introduction port is located within the range of the opening, or the optical fiber is provided at the end portion of the fiber hole. A guide groove for guiding to the fiber hole is continuously provided, and an end portion of the guide groove is located within the range of the opening.

[0009] Preferably, when the opening is viewed upward, the end portion of the fiber hole that opens to the introduction port in the second or more stages from the bottom,
Alternatively, some end portions of vertically adjacent guide grooves in the second or more stages from the bottom may be arranged and provided at the same position. It is also preferable that the opening is viewed from above and the opening 2
The end of the fiber hole that opens to the introduction port at the second or higher step or the end of the vertically adjacent guide groove at the second or higher step from the bottom is arranged at the same position.

In order to achieve the above-mentioned object in the present invention, a pin hole through which a guide pin is inserted, and a plurality of fibers formed between the pin holes and having one end opened to the front end face and through which an optical fiber is inserted. A ferrule having a hole and an introduction port communicating with the other ends of the plurality of fiber holes and opening at a rear end face to introduce the optical fiber, wherein the plurality of fiber holes are vertically arranged in a plurality of stages. The guide groove for guiding the optical fiber to the fiber hole is formed continuously at the end portion which is formed and communicates with the introduction port.

At this time, the plurality of fiber holes have a length of 1/8 to 3/4 of the total length of the ferrule. Preferably, the end portions of the fiber holes that open to the introduction ports in the second or more steps from the bottom or the end portions of vertically adjacent guide grooves in the second or more steps from the bottom are arranged and provided at the same position. There is a configuration.

[0012] Preferably, the end of the fiber hole that opens to the introduction port in the second or more stages from the bottom, or 2 from the bottom.
The end portions of the guide grooves vertically adjacent to each other at the step or higher are arranged at the same position.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of a multi-core multi-stage ferrule of the present invention will be described in detail below with reference to FIGS. First, a multi-core multi-stage ferrule (hereinafter, simply referred to as “ferrule”) according to the first embodiment will be described.

The ferrule 10 is made of a synthetic resin such as a polyphenylene sulfide (PPS) resin or an epoxy resin, as shown in FIGS. 1 and 2, and has a collar portion 10b formed at the rear portion of the body 10a and substantially at the center thereof. An inlet 10c extending in the front-rear direction and opening on the rear end face Fr of the collar portion 10b.
Are formed. The introduction port 10c communicates with a plurality of fiber holes 10f and openings 10d described later. The ferrule 10 has an opening 10d formed on the upper surface of the main body 10a, the opening 10d communicating with the inlet 10c and injecting an adhesive. Further, the ferrule 10 is formed with two pin holes 10e through which guide pins are inserted along the longitudinal direction on both sides, and between the two pin holes 10e at the front part of the main body 10a, one step for inserting an optical fiber is provided. Eight fiber holes 10f are vertically formed in three stages.

As shown in FIG. 2, the third-stage fiber hole 10f has the opening 10d at the second or more stages from the bottom, that is, the end portions which open to the middle and upper inlets 10c as seen from above.
It is formed so as to be located within the range of d. On the other hand, as shown in the figure, a guide groove 10g for guiding the optical fiber is continuously provided in the lower fiber hole 10f when the opening 10d side is viewed upward. In the three-stage fiber 10f, the ends that open to the second or more introduction ports 10c from the bottom are arranged at the same position in the front-rear direction, and there are two stages provided at the same position.

The ferrule 10 configured as described above
Is assembled into an optical connector by adhesively fixing an optical fiber to each of the plurality of fiber holes 10f with an adhesive injected from the opening 10d. At this time, ferrule 10
Among the three-stage fiber holes 10f, when the opening 10d is viewed upward, the end portion that opens to the introduction port 10c at the second or higher stage from the bottom is located within the range of the opening 10d. Therefore, ferrule 1
As is clear from the comparison between FIG. 2 and FIG. 9, the 0 is the three-stage fiber hole 10f, and the lower two stages are the conventional ferrule 1
Since it is shorter and has the same length, it can be molded with a short core pin. Therefore, in the ferrule 10, as compared with the conventional ferrule 1, the core pin is less likely to bend due to the resin pressure during molding, and the fiber hole 10f can be molded with high accuracy. Moreover, since the ferrule 10 has a smaller opening 10d than the conventional ferrule 1, even if the synthetic resin forming the ferrule 10 and the adhesive have different linear expansion coefficients when assembled into an optical connector, the opening 10d will not be opened. No warpage occurs on the side of the front end face Ff located.

Next, the ferrule according to the second embodiment will be described. As shown in FIGS. 3 and 4, the ferrule 15 has a flange portion 15b formed at the rear portion of the main body 15a, and an introduction port 15c that extends in the front-rear direction at substantially the center and opens to the rear end face Fr of the flange portion 15b. Has been done. Inlet 15
c is a plurality of fiber holes 15f and openings 15d described later.
Is in communication with. The ferrule 15 communicates with the introduction port 15c on the upper surface of the main body 15a, and an opening 15d for injecting an adhesive agent.
Are formed. In addition, the ferrule 15 is on both sides,
Two pin holes 1 for inserting the guide pins along the longitudinal direction
5e are formed, and two pin holes 15e in the front part of the main body 15a are formed.
In between, eight fiber holes 15f for each stage through which the optical fiber is inserted are formed in three stages in the vertical direction.

As shown in FIG. 4, the three-stage fiber hole 15f has an optical fiber at the end of the fiber hole 15f located at the upper third stage from the bottom when the opening 15d is viewed upward. A guide groove 15g for guiding to is continuously provided, and the end portion of the guide groove 15g is formed so as to be located within the range of the opening 15d. On the other hand, the middle and lower fiber holes 1
5f is formed such that the end opening to the inlet 15c is positioned in the middle of the range of the opening 15d, and the lower fiber hole 15f has a guide groove 15g for guiding the optical fiber as shown in the figure. It is lined up.

The ferrule 15 constructed as described above
Is assembled into an optical connector in the same manner as the ferrule 10 and the opening 15d is smaller than the opening 1d of the ferrule 1 even if the synthetic resin forming the ferrule 15 and the adhesive have different linear expansion coefficients. No warpage occurs on the front end face Ff side where is located. Moreover, the ferrule 15 has the three-stage fiber holes 15f formed as described above, and the lower-stage fiber hole 15f is shorter than the lower-stage fiber hole 1f of the conventional ferrule 1. Therefore, the ferrule 15 has an effect that the opening 15d is smaller than the opening 1d of the ferrule 1 as compared with the conventional ferrule 1, the core pin is hard to bend due to the resin pressure at the time of molding, and the fiber hole 1f is molded with high accuracy. can do.

At this time, the ferrule 15 has the guide groove 1
An optical fiber is inserted into the middle-stage fiber hole 15f not having 5g as follows. That is, in such a case,
The optical fiber insertion tool 5 shown in FIGS. 5 and 6 is used. As shown in FIG. 5, the insertion tool 5 includes a substrate 6 and pin holding portions 7 formed on both sides of the substrate 6.

As shown in FIG. 5, the substrate 6 is formed so as to protrude from the pin holding portion 7, and a plurality of guide grooves 6a for guiding the optical fiber are provided on the upper surface. Guide groove 6
a is on the same straight line as the fiber hole of the ferrule used. The pin holding portion 7 has an insertion hole 7a formed in the front-rear direction in which a guide pin 3 described later is inserted.

Then, as shown in FIG. 6, the guide pin 3
Then, the substrate 6 is arranged so as to face the introduction port 15c of the ferrule 15 with the pin holding portion 7 of the insertion tool 5 on the rear side. Next, the substrate 6 is inserted into the introduction port 15c of the ferrule 15, and each guide pin 3 is inserted into the pin hole 15 of the ferrule 15.
The insertion tool 5 is positioned with respect to the ferrule 15 by inserting it into the e and the insertion hole 7a of the pin holding portion 7. This allows
In the insertion tool 5, the substrate 6 is arranged at the upper edge of the lower guide groove 15g, and each guide groove 6a is arranged at a position corresponding to the middle fiber hole 15f.

In this state, as shown in FIG. 7, the bare fiber 4b exposed by removing the coating 4a from the tip of the optical fiber 4 is introduced into the introduction port 15c while being guided to the guide groove 6a. Then, the bare fiber 4b becomes the ferrule 15
Even if there is no guide groove in the
Guided by each guide groove 6a, it is smoothly and easily inserted into the fiber hole 15f in the middle stage.

Next, the ferrule according to the third embodiment having no opening for injecting an adhesive will be described. The ferrule 20 is, as shown in FIGS.
The main body 20a is formed of the same synthetic resin as the above, and a collar portion 20b is formed at the rear portion of the main body 20a, and an introduction port 20c that extends in the front-rear direction and is opened to the rear end face Fr of the collar portion 20b is formed at substantially the center. The introduction port 20c communicates with a plurality of fiber holes 20f described later. The ferrule 20 has two pin holes 20e for inserting the guide pins along the longitudinal direction formed on both sides, and between the two pin holes 20e at the front part of the main body 20a, there are eight pin holes 20e per stage for inserting an optical fiber. The fiber hole 20f is formed in three steps in the vertical direction.

The three-stage fiber hole 20f is used for the ferrule 2
0 has a length of 1/8 to 3/4 of the total length, and as shown in FIG. 9, the lower fiber hole 20f is continuously provided with a guide groove 20g for guiding an optical fiber. In the three-stage fiber hole 20f, the ends that open to the second or more introduction ports 20c from the bottom are arranged at the same position in the front-rear direction, and there are two stages provided at the same position.

Here, in the ferrule, the connection end face (front end face) is generally polished after the optical fiber is bonded and fixed to each fiber hole. Therefore, considering the quality of the ferrule 20 after polishing the end surface, the fiber hole 20f is
It must be 1/8 or more of the total length of the ferrule 20. Further, the ferrule 20 is provided with a boot on the rear side when assembled into an optical connector, and an optical fiber (tape core wire) extends. For this reason, in the ferrule 20, considering the holding of the boot and the optical fiber provided on the rear side, it is necessary to secure a length of a portion for holding the boot and the optical fiber of 1/4 or more of the entire length. Therefore, the fiber hole 20f needs to be set to 3/4 or less of the total length of the ferrule 20.

The ferrule 20 constructed as described above
Unlike the ferrule 10, the optical fiber is bonded and fixed to each of the plurality of fiber holes 20f by the adhesive injected from the introduction port 20c to be assembled into the optical connector. At this time, the ferrule 20 has three stages of fiber holes 2
0f has a length of 1/8 to 3/4 of the total length of the ferrule 20. Therefore, the ferrule 20 is the ferrule 1
Like the conventional ferrule 1, the core pin is less likely to bend due to the resin pressure during molding, and the fiber hole 20
It is possible to mold f with high accuracy. Moreover, since the ferrule 20 does not have an opening, even when the synthetic resin and the adhesive forming the ferrule 20 have different linear expansion coefficients when assembled into the optical connector, the front end face Ff side corresponding to the opening is formed. The warp does not occur.

Next, a ferrule according to the fourth embodiment will be described. As shown in FIG. 10, the ferrule 25 has a collar portion 25b formed at the rear portion of the main body 25a, extends in the front-rear direction at substantially the center, and has a rear end face Fr at the collar portion 25b.
An inlet port 25c that opens to the bottom is formed. Inlet 25c
Communicate with a plurality of fiber holes 25f described later.
The ferrule 25 has two pin holes 25e formed on both sides for inserting guide pins along the longitudinal direction, and has a main body 25a.
Between the two front pin holes 25e, eight fiber holes 25f for each step through which the optical fiber is inserted are formed in three steps in the vertical direction.

The three-stage fiber hole 25f is used for the ferrule 2
5 has a length of 1/8 to 3/4 of the total length, and as shown in FIG. 10, the fiber hole 25f at the third stage from the bottom has a guide groove 25g for guiding the optical fiber continuously provided at the end thereof. ing. On the other hand, as shown in the figure, a guide groove 25g for guiding the optical fiber is continuously provided in the lower fiber hole 25f. In the three-stage fiber 25f, the ends of the fiber holes 25f that open to the second or more introduction ports 25c from the bottom are arranged on the front end face Ff side above the lower stage.
There are two steps in which the end of 5f is provided at least at the same position in the front-rear direction.

Ferrule 25 constructed as described above
Is assembled to the optical connector in the same manner as the ferrule 10. At this time, since the ferrule 25 has the three-stage fiber holes 25f formed as described above, the core pin is less likely to bend due to the resin pressure at the time of molding as compared with the conventional ferrule 1, and the fiber hole 25f can be formed with high accuracy. It can be molded. Moreover, since the ferrule 25 does not have an opening, when assembled into an optical connector, as with the ferrule 20, warpage does not occur on the front end face Ff side corresponding to the opening.

Although the above embodiment describes the ferrule in which eight fiber holes are formed per stage,
The number of fiber holes is not limited to eight. Also,
It goes without saying that the number of stages of the plurality of fiber holes is not limited to three and may be one stage, two stages or four or more stages. In addition, in the multi-core multi-stage ferrule of the present invention, the end of the fiber hole that opens to the introduction port of the second or more stages from the bottom, or the end of the vertically adjacent guide grooves of the second or more stages from the bottom is the same. If there is a guide groove that is provided at a position, the other guide grooves that are vertically adjacent to each other may be provided on the front end surface side of the lower stage than the upper stage, or vice versa. It may be arranged on the front end face side or either of them.

[0032]

According to the inventions of claims 1 to 7, it is possible to provide a multi-core multi-stage ferrule which can be molded with high accuracy without bending the fiber hole.

[Brief description of drawings]

FIG. 1 is a plan view showing a first embodiment of a multi-core multi-stage ferrule of the present invention.

2 is a cross-sectional view of the ferrule of FIG.

FIG. 3 is a plan view showing a second embodiment of the multi-core multi-stage ferrule of the present invention.

4 is a cross-sectional view of the ferrule of FIG.

5 is a perspective view of an insertion tool for inserting an optical fiber into a fiber hole of the ferrule of FIG.

6 is a perspective view showing how to use the insertion tool shown in FIG. 5. FIG.

7 is a cross-sectional view showing a state where an optical fiber is inserted into a ferrule by using a guide groove formed in a substrate of the insertion tool shown in FIG.

FIG. 8 is a plan view showing a third embodiment of a multi-core multi-stage ferrule of the present invention.

9 is a cross-sectional view of the ferrule of FIG.

FIG. 10 is a cross-sectional view showing a fourth embodiment of the multi-core multi-stage ferrule of the present invention.

FIG. 11 is a plan view of a conventional ferrule.

12 is a cross-sectional view of the ferrule of FIG.

13 is a cross-sectional view of the optical connector, in which an optical fiber is adhesively fixed to the fiber hole of the ferrule of FIG. 11, cut in the width direction.

[Explanation of symbols]

10,15 ferrule 10a, 15a body 10b, 15b collar part 10c, 15c inlet 10d, 15d opening 10e, 15e pin hole 10f, 15f Fiber hole 10g, 15g guide groove 20,25 ferrule 20a, 25a body 20b, 25b collar part 20c, 25c inlet 20e, 25e pin hole 20f, 25f fiber hole 20g, 25g guide groove Ff front end face Fr rear end face

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Takashi Shigenaga             2-6-1, Marunouchi, Chiyoda-ku, Tokyo             Kawa Electric Industry Co., Ltd. F-term (reference) 2H036 JA02 QA13 QA18 QA20 QA23

Claims (7)

[Claims] 1. A pin hole through which a guide pin is inserted, a plurality of fiber holes formed between the pin holes and through which optical fibers are inserted, and a plurality of fiber holes are communicated with each other and an adhesive is injected. A ferrule formed with an opening, extending in the front-rear direction in the approximate center, opening to a rear end face in communication with the plurality of fiber holes and the opening, and wherein the optical fiber is introduced into the ferrule, A plurality of stages of fiber holes are formed, and the plurality of stages of fiber holes are formed from the bottom when viewed from above.
An end portion of the step or more that opens to the introduction port is located within the range of the opening, or a guide groove for guiding the optical fiber to the fiber hole is continuously provided at the end portion of the fiber hole, and the guide. A multi-core multi-stage ferrule, wherein an end of the groove is located within the range of the opening. 2. When the opening is viewed upward, the end of the fiber hole that opens to the introduction port at the second or higher step from the bottom or the end of the vertically adjacent guide groove at the second or higher step from the bottom is The multi-core multi-stage ferrule according to claim 1, wherein some of the ferrules are arranged at the same position. 3. When the opening is viewed upward, the end of the fiber hole that opens to the introduction port at the second or higher step from the bottom or the end of the vertically adjacent guide grooves at the second or higher step from the bottom is The multi-core multi-stage ferrule of claim 1, wherein the ferrules are arranged at the same position. 4. A pin hole into which a guide pin is inserted, a plurality of fiber holes formed between the pin holes, one end of which is opened to a front end face and through which an optical fiber is inserted, and the other ends of the plurality of fiber holes. A ferrule in which a plurality of fiber holes are formed in a plurality of stages in the vertical direction and communicate with the introduction port, the ferrule having an introduction port through which the optical fiber is introduced and which opens to the rear end surface in communication with the ferrule. A multi-core multi-stage ferrule, wherein a guide groove for guiding the optical fiber to the fiber hole is continuously provided at an end portion. 5. A pin hole into which a guide pin is inserted, a plurality of fiber holes formed between the pin holes, one end of which opens to a front end face, and an optical fiber is inserted, and the other end of the plurality of fiber holes. A plurality of fiber holes, each of which is 1/8 of a total length of the ferrule.
It has a length of up to 3/4 and is formed in a plurality of stages in the vertical direction, and a guide groove for guiding the optical fiber to the fiber hole is continuously provided at an end communicating with the introduction port. Featuring a multi-core multi-stage ferrule. 6. The end portions of the fiber holes that open to the introduction ports in the second or more steps from the bottom or the end portions of vertically adjacent guide grooves in the second or more steps from the bottom are arranged at the same position. The multi-fiber multi-stage ferrule according to claim 4 or 5, wherein: 7. The end of the fiber hole that opens to the introduction port at the second or higher step from the bottom or the end of the vertically adjacent guide grooves at the second or higher step from the bottom is arranged at the same position. The multi-fiber multi-stage ferrule according to claim 4.