JPH0153763B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an optical fiber terminal mechanism for optically connecting optical fibers or optical fibers to other equipment, and a method for assembling the same.

2. Description of the Related Art Conventionally, optical fiber connecting devices for optically connecting optical fibers have a structure as shown in FIG. 1. In FIG. 1, the optical fiber connection device includes an adapter 1, a ferrule 2,
It consists of an optical fiber 3 and a cap nut 4. An optical fiber guide hole 5 for guiding the optical fiber 3 is provided at the axial center of the tip of the cylindrical ferrule 2. optical fiber 3
is inserted into the guide hole 5 until one end surface 6 is flush with one end surface 7 of the ferrule 2, and is fixed in this state with an adhesive 8 such as epoxy resin. With the optical fiber 3 fixed in the guide hole 5, the pair of ferrules 2 are slidably fitted into the cylindrical adapter 1 from the end face 7 side, and the end face 7
They are in contact with each other. Further, a cap nut 4 is screwed and fixed to the adapter 1, and the position of the ferrule 2 is regulated by the cap nut 4 so that it does not fall off from the adapter 1.

In the above configuration, the one end surfaces 6 of the optical fibers 3 fixed to the axial center portion of the tip portion of the ferrule 2 are in opposing contact with each other, and the optical fibers 3 are optically connected to each other.

However, when assembling the optical fiber connecting device, the adhesive 8 must be cured in order to fix the optical fiber 3 into the ferrule 2.
The adhesive 8 such as epoxy resin requires several hours or more to harden, and the optical fiber 3 is not fixed in the ferrule 2 in a short time. Furthermore, in order to bring the end surfaces 6 of the optical fibers 3 into opposing contact with each other, it is necessary to remove the adhesive 8 protruding from the end surfaces 7 by polishing the end surfaces 7 after the adhesive 8 has hardened. Therefore, the optical fiber connection device as shown in FIG. 1 cannot be used immediately after assembly. In addition, by inserting the ferrules 2 into the common adapter 1, the one end surfaces 6 of the optical fibers 3 are made to face each other, so that the guide hole 5 is inserted into the ferrule 2.
It must be located exactly on the axis of the However, drilling a hole around 100 μm in diameter with an eccentricity of less than a few μm in the axial center of ferrule 2 requires high-precision machining equipment and a high level of skill. As a result, optical fiber connection equipment becomes expensive. Become something.

The present invention was invented to solve the above-mentioned problems, and is an optical fiber that can be used immediately after assembly, allows easy radial positioning of optical fibers, and is easy to assemble. The purpose is to provide a fiber terminal mechanism.

Embodiments of the present invention will be described below with reference to FIGS. 2 and 3.

FIG. 2 shows an embodiment of the present invention applied to an optical fiber connecting device for optically connecting optical fibers. Note that FIG. 2 shows only the right half of the optical fiber connection device, and in reality there is also a left half that is symmetrical to this. In this FIG. 2, the optical fiber connection device consists of an adapter 21, an optical fiber terminal mechanism 22, and a cap nut 23.

The terminal mechanism 22 includes a cylindrical support member such as a housing 24, an optical fiber attachment member such as an optical fiber plug 25, and a cap nut 26 for tightening.

The housing 24 is made of metal or the like, and one end 29 thereof has a tapered shape so that it can be fluid-tightly tightened with a cap nut 26 when the optical fiber cord 27 is inserted. A stepped portion 52 is formed on the inner surface of the side end portion 30 so that the plug 25 can be attached in a liquid-tight manner. Further, in the wall of the housing 24, a through hole 28 for temporarily fixing the plug 25, which is a means for temporarily fixing the plug 25 to the housing 24, and a plug 2 are provided.
5 and the optical fiber 48 to the housing 24 are formed therein. An adhesive injection through hole 31 and an air vent hole 32 are formed to be used when injecting the adhesive 54 to permanently fix the optical fiber 5 and the optical fiber 48 to the housing 24.

The plug 25 includes a ferrule 33 having a substantially cylindrical shape, a condensing/parallel light converting lens such as a gradient index lens 34, an optical fiber support 35, and a distal end portion of the plug 25 inserted through the support 35. It consists of an optical fiber 48 to which is attached.
The ferrule 33 has a flange portion 51 that comes into contact with a stepped portion 52 of the housing 24 so as to be attached to the housing 24 in a liquid-tight manner, and is made of metal such as stainless steel,
It is made of synthetic resin or ceramics. The refractive index gradient lens 34 is made of glass, synthetic resin, etc., and its length is approximately an odd multiple of 1/4 pitch of the meandering period of the light. A cover glass is attached. The support body 35 is made of glass, synthetic resin, metal, ceramics, etc. and has a substantially cylindrical shape, and its outer diameter is somewhat smaller than the inner diameter of the ferrule 33. Further, an insertion hole 39 for inserting an optical fiber 48 is formed in the axial center portion of the support body 35, and an outer end of this insertion hole 39 is formed to allow the optical fiber 48 to pass through the insertion hole 39.
A tapered opening 40 is formed to guide the. An optical fiber 48 is inserted into this insertion hole 39.
is inserted and fixed until it contacts the lens 34.

The procedure for assembling the plug 25 having the above structure will be explained with reference to FIG. First, the lens 34 is adhesively fixed inside the ferrule 33, and the support body 35 is attached to the ferrule 33.
simply insert it into the support device 3 in front of the collimated light source 36 as shown in FIG.
At the same time, an optical fiber 38 for measuring the amount of light is inserted into the insertion hole 39 of the support 35, and the tip end surface of the optical fiber 38 is brought into close contact with the end surface of the lens 34. Further, another optical fiber plug 41 is connected to the other end of the optical fiber 38 in advance. Note that this other plug 41 may also have substantially the same configuration as that shown in FIG. 2, and may already be assembled. Then, the light emitted from the optical fiber 38 is converted into parallel light by this other plug 41, and this parallel light is received by a light receiving element 42, and the amount of received light is monitored by a light amount monitor 43.
Measure with. In the above measurement system, the light source 36
The parallel light beam 44 from the lens 34 in the plug 25
While measuring the amount of light transmitted through the optical fiber 38 with the monitor 43, the support body 35 in the plug 25 is moved in a direction perpendicular to the optical axis to determine the position where the amount of received light peaks, that is, the light of the lens 34. Find a position where the shaft and the central axis of the support body 35 coincide. At this position, the support 35 is fixed to the ferrule 33 with adhesive 49, and the optical fiber 38 is attached to the support 35.
extract it from Through hole 3 of fixed support 35
The optical fiber 48 to be inserted into the optical fiber cord 9 is obtained by removing the outer sheath 45, the buffer member 46 and the inner sheath 47 of the optical fiber cord 27 by a predetermined length, respectively. This exposed optical fiber 48
through the insertion hole 39 of the support 35 fixed to the plug 25 until its end surface abuts the end surface of the lens 34.
and fix it with adhesive 50 near the opening 40.

Next, the procedure for assembling the terminal mechanism 22 will be explained.
The plug 25 into which the tip of the optical fiber 48 is inserted and fixed is inserted into the housing 24 from the right side in FIG. 2 until the flange 51 of the ferrule 33 abuts the step 52 on the inner surface of the housing 24. In this case, since the flange portion 51 abuts against the step portion 52, the space between the plug 25 and the housing 24 becomes liquid-tight. Plug 25 and fiber optic cord 2
7, the temporary fixing through hole 28 is filled with an instant adhesive 53 such as cyanoacrylate, and the plug 25 is temporarily fixed to the housing 24. Then, the cap nut 23 is slidably fitted into the outer wall of the housing 24 from the right side in FIG. Next, by screwing the cap nut 26 into the housing 24, the tapered portion formed at one end 29 of the housing 24 is tightened, and the optical fiber cord 27 is fixed to the housing 24 in a fluid-tight manner. After that, in order to permanently fix the plug 25 and the optical fiber cord 27 to the housing 24, an adhesive 54 such as an epoxy resin is overflowed through the adhesive injection hole 31, and the adhesive 54 overflows from the air vent hole 32. Inject until In this case, since the exposed portion of the optical fiber 48 from the optical fiber cord 27 is selected to be longer than the length of the support 35, the optical fiber 48 comes into contact with the adhesive 54, and the buffer member 46 or inner coating 47 is bonded. The adhesive force is increased compared to the case of contact with the agent 54. When the injection of the adhesive 54 is completed, the adhesive injection hole 31 and the air vent hole 32 are sealed with tape or the like. In the above assembly procedure, after temporarily fixing the plug 25 to the housing 24, the optical fiber cord 27 is fixed to the housing 24 in a fluid-tight manner by screwing the cap nut 26 into the housing 24. After that, adhesive 54 for permanent fixing was injected, but the step of temporarily fixing the plug 25 was to attach the optical fiber cord 27 to the housing 2.
This may be carried out after the step of liquid-tightly fixing the adhesive 54 to the fixing member 4 or after the step of injecting the adhesive 54 for main fixing.

In the terminal mechanism 22 configured as described above, if the plug 25 is inserted into the housing 24 and the temporary fixing hole 28 is filled with the instant adhesive 53, the plug 2
5 is immediately temporarily fixed to the housing 24,
At that time, the plug 25 and the optical fiber cord 27 are respectively liquid-tight with respect to the housing 24.
Furthermore, after the adhesive 54 is injected, the adhesive injection through hole 31 is
Since the air vent hole 32 may be sealed with tape or the like, the adhesive 54 injected into the housing 24 will not leak out even before the adhesive 24 has hardened. Also, adhesive 53 for fixing the plug 25
does not adhere to the end face of the lens 34,
There is no need to polish the end face of the lens 34 again. Therefore, even immediately after assembling the terminal mechanism 22, the plug 25 must be inserted into the adapter 21 and the cap nut 2
3 is screwed into the adapter 21 and can be used immediately as an optical fiber connection device.

Further, since the support body 35 is fixed at the optical axis position of the lens 34 by the above-described procedure, the accuracy of the center position of the insertion hole in the support body 35 does not matter. Therefore, the terminal mechanism 22 does not require high-precision machining, and can be manufactured at low cost.

Furthermore, in the optical fiber connection device shown in FIG. 1, since the end surfaces 6 of the optical fibers 3 are brought into opposing contact with each other, there is a possibility that the optical fibers 3 may be chipped, which may cause connection loss. There is a risk that the core diameter of the optical fiber 3 is generally 50 μm.
Even a small amount of dust adhering to one end surface 6 causes a connection loss, and therefore, such an optical fiber connection device inevitably becomes unreliable. However, in the terminal mechanism 22 used in the optical fiber connection device shown in FIG. 2, the light emitted radially from one end surface of the optical fiber 48 is expanded by the lens 34 until it becomes parallel light The parallel light incident on the end face of the lens 34 is converged on one end face of the optical fiber 48. Therefore, even when optical fibers are optically connected, the adapter 21
Since there is no need to mechanically bring the lenses 34 of a pair of terminal mechanisms 22 into opposing contact with each other, the lenses 34
Damage to the terminal mechanism 22 can be prevented, and even if dust adheres to a part of the end surface of the lens 34, the rate of connection loss is small, and therefore the reliability of the terminal mechanism 22 is extremely high.

Although the present invention has been described above with reference to embodiments, the present invention is not limited to these embodiments and can be further modified in various ways.

For example, in the optical fiber plug 25, a spherical lens having a condensing/parallel light conversion function may be used instead of the gradient index lens 34, and the material of this spherical lens may be glass, synthetic resin, etc. That's good. In addition, instead of filling the temporary fixing hole 28 with the instant adhesive 33, a female screw is formed on the inner surface of the temporary fixing hole 28, and a male screw without a screw head is screwed into the female screw. , the optical fiber plug 25 may be temporarily fixed to the housing 24. Furthermore, an optical fiber plug 25 and a housing 24
The flange portion 51 and the stepped portion 52, which are in contact with the inner surface of the flange portion 51 to be liquid-tight, may be formed into a tapered shape that fits into each other.

As described above, the present invention is configured such that the distal end of the optical fiber is attached to a mounting member, the mounting member is disposed in a support member, and the mounting member is temporarily fixed to the support member by a temporary fixing means. . Therefore,
The optical fiber terminal mechanism according to the present invention has the advantage that it can be used immediately after assembly. Further, the mounting member to which the tip end of the optical fiber is attached is attached to the cylindrical support member. Therefore, compared to the case where the tip of the optical fiber is directly attached to a cylindrical support member, the radial positioning operation of the optical fiber is easier, and the tip of the optical fiber can be temporarily fixed directly to the support member. Since there is no need to temporarily fix the mounting members, the assembly work is also simple.

[Brief explanation of drawings]

Fig. 1 is a schematic sectional view of a conventional example of an optical fiber connection device, Fig. 2 is a schematic sectional view of an embodiment of an optical fiber connection device to which the present invention is applied, and Fig. 3 is similar to Fig. 2. FIG. 3 is a schematic diagram showing a part of the assembly procedure of the optical fiber terminal mechanism shown in FIG. In addition, in the symbols used in the drawings, 24
...Housing, 25...Fiber optic plug, 28...
Temporary fixing through hole, 48...optical fiber, 54...adhesive.

Claims (1)

[Scope of Claims] 1. A mounting member to which a distal end of an optical fiber is attached, and an intermediate portion of the optical fiber located inside the distal end thereof is attached to one end thereof, and the mounting member is attached to the other end. a cylindrical support member attached to the section; temporary fixing means for temporarily fixing the attachment member to the support member; and permanently fixing the attachment member and the intermediate portion of the optical fiber to the support member. and an adhesive filled in a hollow portion of the support member, so that the attachment member can be inserted into the support member from the one end to the other end of the support member. Optical fiber terminal mechanism configured as follows. 2. Inserting the mounting member to which the tip of the optical fiber is attached from one end of the cylindrical support member to the other end, and liquid-tightly mounting the mounting member to the other end; Temporarily fixing the attachment member to the support member through a temporary fixation through hole formed in the support member; and a step of injecting an adhesive into the hollow part of the support member through an adhesive injection hole formed in the support member to attach the support member to the support member. A method for assembling an optical fiber terminal mechanism, comprising the steps of permanently fixing a member and the optical fiber.